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Nieuwenhoff MD, Nguyen HT, Niehof SP, Huygen FJPM, Verma A, Klaassen ES, Bechakra M, Geelhoed WJ, Jongen JLM, Moll AC, Vrancken AFJE, Petzold A, Groeneveld GJ. Differences in corneal nerve fiber density and fiber length in patients with painful chronic idiopathic axonal polyneuropathy and diabetic polyneuropathy. Muscle Nerve 2024. [PMID: 39056231 DOI: 10.1002/mus.28213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 07/05/2024] [Accepted: 07/14/2024] [Indexed: 07/28/2024]
Abstract
INTRODUCTION/AIMS Corneal confocal microscopy (CCM) detects small nerve fiber loss and correlates with skin biopsy findings in diabetic neuropathy. In chronic idiopathic axonal polyneuropathy (CIAP) this correlation is unknown. Therefore, we compared CCM and skin biopsy in patients with CIAP to healthy controls, patients with painful diabetic neuropathy (PDN) and diabetics without overt neuropathy (DM). METHODS Participants with CIAP and suspected small fiber neuropathy (n = 15), PDN (n = 16), DM (n = 15), and healthy controls (n = 16) underwent skin biopsy and CCM testing. Inter-center intraclass correlation coefficients (ICC) were calculated for CCM parameters. RESULTS Compared with healthy controls, patients with CIAP and PDN had significantly fewer nerve fibers in the skin (IENFD: 5.7 ± 2.3, 3.0 ± 1.8, 3.9 ± 1.5 fibers/mm, all p < .05). Corneal nerve parameters in CIAP (fiber density 23.8 ± 4.9 no./mm2, branch density 16.0 ± 8.8 no./mm2, fiber length 13.1 ± 2.6 mm/mm2) were not different from healthy controls (24.0 ± 6.8 no./mm2, 22.1 ± 9.7 no./mm2, 13.5 ± 3.5 mm/mm2, all p > .05). In patients with PDN, corneal nerve fiber density (17.8 ± 5.7 no./mm2) and fiber length (10.5 ± 2.7 mm/mm2) were reduced compared with healthy controls (p < .05). CCM results did not correlate with IENFD in CIAP patients. Inter-center ICC was 0.77 for fiber density and 0.87 for fiber length. DISCUSSION In contrast to patients with PDN, corneal nerve parameters were not decreased in patients with CIAP and small nerve fiber damage. Therefore, CCM is not a good biomarker for small nerve fiber loss in CIAP patients.
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Affiliation(s)
- Mariska D Nieuwenhoff
- Department of Anesthesiology and Pain Medicine, Erasmus MC University Medical Center, Rotterdam, The Netherlands
- Centre for Human Drug Research, Leiden, The Netherlands
| | - Hoang-Ton Nguyen
- Department of Ophthalmology, Amsterdam UMC location VU University Medical Center, Amsterdam, The Netherlands
| | - Sjoerd P Niehof
- Department of Anesthesiology and Pain Medicine, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Frank J P M Huygen
- Department of Anesthesiology and Pain Medicine, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | | | | | - Malik Bechakra
- Department of Anesthesiology and Pain Medicine, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | | | - Joost L M Jongen
- Department of Anesthesiology and Pain Medicine, Erasmus MC University Medical Center, Rotterdam, The Netherlands
- Department of Neurology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Annette C Moll
- Department of Ophthalmology, Amsterdam UMC location VU University Medical Center, Amsterdam, The Netherlands
| | - Alexander F J E Vrancken
- Department of Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Axel Petzold
- Department of Ophthalmology, Amsterdam UMC location VU University Medical Center, Amsterdam, The Netherlands
- Department of Neurology, Amsterdam UMC location VU University Medical Center, Amsterdam, The Netherlands
- Moorfields Eye Hospital, The National Hospital for Neurology and Neurosurgery and the Queen Square Institute of Neurology, UCL, London, UK
| | - Geert Jan Groeneveld
- Centre for Human Drug Research, Leiden, The Netherlands
- Department of Anesthesiology, Leiden University Medical Center, Leiden, The Netherlands
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Moin KA, Pandiri S, Manion GN, Brown AH, Moshirfar M, Hoopes PC. The Utilization of Topical Insulin for Ocular Surface Diseases: A Narrative Review. Cureus 2024; 16:e62065. [PMID: 38989397 PMCID: PMC11235153 DOI: 10.7759/cureus.62065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/09/2024] [Indexed: 07/12/2024] Open
Abstract
Various etiologies, including diabetic keratopathy (DK), dry eye disease (DED), and neurotrophic keratopathy (NK), can disrupt corneal homeostasis, exacerbating corneal epithelial defects. Topical insulin has emerged as a promising therapy for promoting corneal wound healing and addressing underlying pathologies. This review systematically evaluates the efficacy of topical insulin across different corneal disorders. A literature review was conducted across the PubMed, Google Scholar, and Scopus research databases. The search resulted in a total of 19 articles, consisting of clinical trials, retrospective studies, and case reports. In DK, topical insulin accelerates corneal wound healing post-vitreoretinal surgery with lower concentrations showing higher outcomes when compared to conventional therapy, possibly due to improved epithelial stem cell migration. In comparison, the dry-eye disease results are inconclusive regarding patient-reported outcomes and corneal staining. For NK, topical insulin accelerates corneal wound healing and restores corneal nerve sensation. Other persistent epithelial defect (PED) etiologies that have been treated with topical insulin are infection, immune-mediated, mechanical and chemical trauma, and chronic ocular surface alterations. Although individual mechanisms for the benefits of topical insulin for each of these etiologies have not been studied, the literature demonstrates that topical insulin is efficacious for PEDs regardless of etiology. Future clinical trials need to be conducted to further evaluate optimal dosing, duration, and use of topical insulin for the restoration of the corneal surface.
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Affiliation(s)
- Kayvon A Moin
- Hoopes Vision Research Center, Hoopes Vision, Draper, USA
| | - Srujay Pandiri
- Ophthalmology, University of Missouri Kansas City School of Medicine, Kansas City, USA
| | - Garrett N Manion
- Ophthalmology, Creighton University School of Medicine, Omaha, USA
| | - Alex H Brown
- Ophthalmology, University of Arizona College of Medicine - Phoenix, Phoenix, USA
| | - Majid Moshirfar
- Eye Banking and Corneal Transplantation, Utah Lions Eye Bank, Murray, USA
- Corneal and Refractive Surgery, Hoopes Vision Research Center, Draper, USA
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3
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Krolo I, Behaegel J, Termote K, de Bruyn B, De Schepper M, Oellerich S, Ní Dhubhghaill S. The role of topical insulin in ocular surface restoration: A review. Surv Ophthalmol 2024:S0039-6257(24)00031-6. [PMID: 38609022 DOI: 10.1016/j.survophthal.2024.04.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 04/02/2024] [Accepted: 04/08/2024] [Indexed: 04/14/2024]
Abstract
Corneal epithelial defects are one of the most common ocular disorders. Restoring corneal integrity is crucial to reduce pain and regain function, but in cases of neurotrophic or desensitized corneas, healing can be significantly delayed. Treating neurotrophic corneas is challenging for ophthalmologists, and surgical intervention is often indicated to manage refractory cases that are unresponsive to medical therapy. Over the last decade, as more expensive therapeutics reach the market, topical insulin has returned to the forefront as an affordable option to improve corneal wound healing. There is still a paucity of data on the use and the efficacy of topical insulin, with no consensus regarding its indications, preparation, or posology. Here we review the literature on topical insulin for corneal and ocular surface pathologies, with a focus on the current evidence, its mechanisms of action, and its safety profile. Additionally, we share our experience in the field and provide a potential framework for future research.
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Affiliation(s)
- Iva Krolo
- Department of Ophthalmology, Universitair Ziekenhuis Brussel, Jette, Belgium; Department of Medicine and Pharmacology, Vrije Universiteit Brussel (VUB), Brussels, Belgium; Oftalmología Médica y Quirúrgica (OMIQ) Research, Barcelona, Spain.
| | - Joséphine Behaegel
- Department of Ophthalmology, Universitair Ziekenhuis Brussel, Jette, Belgium; Department of Medicine and Pharmacology, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Karolien Termote
- Department of Ophthalmology, Universitair Ziekenhuis Brussel, Jette, Belgium; Department of Medicine and Pharmacology, Vrije Universiteit Brussel (VUB), Brussels, Belgium; Department of Ophthalmology, Imelda Hospital, Bonheiden, Belgium
| | - Barbara de Bruyn
- Department of Ophthalmology, Antwerp University Hospital, Edegem, Belgium; Department of Medicine, Antwerp University Hospital, Antwerp, Belgium
| | - Manon De Schepper
- Department of Medicine, Antwerp University Hospital, Antwerp, Belgium
| | - Silke Oellerich
- Department of Ophthalmology, Universitair Ziekenhuis Brussel, Jette, Belgium; Department of Medicine and Pharmacology, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Sorcha Ní Dhubhghaill
- Department of Ophthalmology, Universitair Ziekenhuis Brussel, Jette, Belgium; Department of Medicine and Pharmacology, Vrije Universiteit Brussel (VUB), Brussels, Belgium; Department of Ophthalmology, Antwerp University Hospital, Edegem, Belgium; Department of Medicine, Antwerp University Hospital, Antwerp, Belgium
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4
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Woronkowicz M, Roberts H, Skopiński P. The Role of Insulin-like Growth Factor (IGF) System in the Corneal Epithelium Homeostasis-From Limbal Epithelial Stem Cells to Therapeutic Applications. BIOLOGY 2024; 13:144. [PMID: 38534414 DOI: 10.3390/biology13030144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 02/18/2024] [Accepted: 02/19/2024] [Indexed: 03/28/2024]
Abstract
The corneal epithelium, comprising three layers of cells, represents the outermost portion of the eye and functions as a vital protective barrier while concurrently serving as a critical refractive structure. Maintaining its homeostasis involves a complex regenerative process facilitated by the functions of the lacrimal gland, tear film, and corneal nerves. Crucially, limbal epithelial stem cells located in the limbus (transitional zone between the cornea and the conjunctiva) are instrumental for the corneal epithelium integrity by replenishing and renewing cells. Re-epithelialization failure results in persistent defects, often associated with various ocular conditions including diabetic keratopathy. The insulin-like growth factor (IGF) system is a sophisticated network of insulin and other proteins essential for numerous physiological processes. This review examines its role in maintaining the corneal epithelium homeostasis, with a special focus on the interplay with corneal limbal stem cells and the potential therapeutic applications of the system components.
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Affiliation(s)
- Małgorzata Woronkowicz
- NDDH, Royal Devon University Healthcare NHS Foundation Trust, Barnstaple EX31 4JB, UK
- Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London EC1V 2PD, UK
| | - Harry Roberts
- West of England Eye Unit, Royal Devon University Healthcare NHS Foundation Trust, Exeter EX2 5DW, UK
- University of Exeter Medical School, Exeter EX1 2HZ, UK
| | - Piotr Skopiński
- Department of Ophthalmology, SPKSO Ophthalmic University Hospital, Medical University of Warsaw, 00-576 Warsaw, Poland
- Department of Histology and Embryology, Medical University of Warsaw, 02-004 Warsaw, Poland
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Balal S, Din N, Ashton C, Ahmad S. Healing of Chemical Injury-Related Persistent Corneal Epithelial Defects With Topical Insulin. Cornea 2023; 42:1000-1004. [PMID: 36729695 DOI: 10.1097/ico.0000000000003145] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 08/01/2022] [Indexed: 02/03/2023]
Abstract
PURPOSE The purpose of this study was to evaluate the effectiveness of insulin eye drops for treating refractory persistent epithelial defects (PEDs). METHODS A prospective, single-center, case series was performed from March 2020 to September 2021. All patients were prescribed insulin eye drops for refractory PEDs that failed on maximum standard medical treatment (including serum eye drops). The drops were used 4 times/day. Patients were followed up at 2 weekly intervals with full slitlamp examination and serial anterior segment photography. The primary end point was resolution of the epithelial defect. RESULTS Eleven eyes of 10 patients were treated with insulin eye drops. The mean age of the cohort was 45.4 + 25 years with a mean follow-up of 195.7 + 114.3 days after re-epithelization. The most common causative condition was chemical injury (n = 5, 60%). Mean baseline PED defect was 41.3 + 55.2 mm 2 . Nine of 11 eyes (82%) fully re-epithelized within a mean time of 62.3 + 34.6 days (range 14-112). In 2 patients who did not achieve re-epithelization, one had a reduction in size from 12.25 mm 2 to 4.5 mm 2 and the other had no response. No recurrence in defect was observed in the group that had fully re-epithelized. CONCLUSIONS This study showed that the use of topical insulin eye drops led to a successful resolution of PED in 9 of 11 cases. We demonstrate the use of insulin for closure of PEDs in chemical eye injury. Larger controlled studies are required to further evaluate this novel therapy.
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Affiliation(s)
- Shafi Balal
- Moorfields Eye Hospital, London, United Kingdom; and
- UCL Institute of Ophthalmology, London, United Kingdom
| | - Nizar Din
- Moorfields Eye Hospital, London, United Kingdom; and
| | | | - Sajjad Ahmad
- Moorfields Eye Hospital, London, United Kingdom; and
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Leong CY, Naffi AA, Wan Abdul Halim WH, Bastion MLC. Usage of topical insulin for the treatment of diabetic keratopathy, including corneal epithelial defects. World J Diabetes 2023; 14:930-938. [PMID: 37383598 PMCID: PMC10294054 DOI: 10.4239/wjd.v14.i6.930] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 03/14/2023] [Accepted: 04/24/2023] [Indexed: 06/14/2023] Open
Abstract
BACKGROUND Diabetic keratopathy (DK) occurs in 46%-64% of patients with diabetes and requires serious attention. In patients with diabetes, the healing of corneal epithelial defects or ulcers takes longer than in patients without diabetes. Insulin is an effective factor in wound healing. The ability of systemic insulin to rapidly heal burn wounds has been reported for nearly a century, but only a few studies have been performed on the effects of topical insulin (TI) on the eye. Treatment with TI is effective in treating DK.
AIM To review clinical and experimental animal studies providing evidence for the efficacy of TI to heal corneal wounds.
METHODS National and international databases, including PubMed and Scopus, were searched using relevant keywords, and additional manual searches were conducted to assess the effectiveness of TI application on corneal wound healing. Journal articles published from January 1, 2000 to December 1, 2022 were examined. The relevancy of the identified citations was checked against predetermined eligibility standards, and relevant articles were extracted and reviewed.
RESULTS A total of eight articles were found relevant to be discussed in this review, including four animal studies and four clinical studies. According to the studies conducted, TI is effective for corneal re-epithelialization in patients with diabetes based on corneal wound size and healing rate.
CONCLUSION Available animal and clinical studies have shown that TI promotes corneal wound healing by several mechanisms. The use of TI was not associated with adverse effects in any of the published cases. Further studies are needed to enhance our knowledge and understanding of TI in the healing of DK.
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Affiliation(s)
- Ching Yee Leong
- Department of Ophthalmology, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur 56000, Wilayah Persekutuan, Malaysia
| | - Ainal Adlin Naffi
- Department of Ophthalmology, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur 56000, Wilayah Persekutuan, Malaysia
| | - Wan Haslina Wan Abdul Halim
- Department of Ophthalmology, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur 56000, Wilayah Persekutuan, Malaysia
| | - Mae-Lynn Catherine Bastion
- Department of Ophthalmology, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur 56000, Wilayah Persekutuan, Malaysia
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7
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Faustino-Barros JF, Saranzo Sant'Ana AM, Dias LC, de Andrade Batista Murashima A, Costa Mendes da Silva LE, Fantucci MZ, Garcia DM, Rocha EM. Distinct Inflammatory and Oxidative Effects of Diabetes Mellitus and Hypothyroidism in the Lacrimal Functional Unit. Int J Mol Sci 2023; 24:ijms24086974. [PMID: 37108138 PMCID: PMC10138510 DOI: 10.3390/ijms24086974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/28/2023] [Accepted: 03/04/2023] [Indexed: 04/29/2023] Open
Abstract
Diabetes mellitus (DM) and hypothyroidism (HT) are prevalent diseases associated with dry eye (DE). Their impact on the lacrimal functional unit (LFU) is poorly known. This work evaluates the changes in the LFU in DM and HT. Adult male Wistar rats had the disease induced as follows: (a) DM: streptozotocin and (b) HT: methimazole. The tear film (TF) and blood osmolarity were measured. Cytokine mRNA was compared in the lacrimal gland (LG), trigeminal ganglion (TG), and cornea (CO). Oxidative enzymes were evaluated in the LG. The DM group showed lower tear secretion (p = 0.02) and higher blood osmolarity (p < 0.001). The DM group presented lower mRNA expression of TRPV1 in the cornea (p = 0.03), higher Il1b mRNA expression (p = 0.03), and higher catalase activity in the LG (p < 0.001). The DM group presented higher Il6 mRNA expression in the TG (p = 0.02). The HT group showed higher TF osmolarity (p < 0.001), lower expression of Mmp9 mRNA in the CO (p < 0.001), higher catalase activity in the LG (p = 0.002), and higher expression of Il1b mRNA in the TG (p = 0.004). The findings revealed that DM and HT induce distinct compromises to the LG and the entire LFU.
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Affiliation(s)
- Jacqueline Ferreira Faustino-Barros
- Department of Ophthalmology, Otorhinolaryngology and Head and Neck Surgery, Ribeirão Preto Medical School, University of São Paulo, Ribeirao Preto 14049-900, Brazil
| | - Ariane Mirela Saranzo Sant'Ana
- Department of Ophthalmology, Otorhinolaryngology and Head and Neck Surgery, Ribeirão Preto Medical School, University of São Paulo, Ribeirao Preto 14049-900, Brazil
| | - Lara Cristina Dias
- Department of Ophthalmology, Otorhinolaryngology and Head and Neck Surgery, Ribeirão Preto Medical School, University of São Paulo, Ribeirao Preto 14049-900, Brazil
| | - Adriana de Andrade Batista Murashima
- Department of Ophthalmology, Otorhinolaryngology and Head and Neck Surgery, Ribeirão Preto Medical School, University of São Paulo, Ribeirao Preto 14049-900, Brazil
| | - Lilian Eslaine Costa Mendes da Silva
- Department of Ophthalmology, Otorhinolaryngology and Head and Neck Surgery, Ribeirão Preto Medical School, University of São Paulo, Ribeirao Preto 14049-900, Brazil
| | - Marina Zílio Fantucci
- Department of Ophthalmology, Otorhinolaryngology and Head and Neck Surgery, Ribeirão Preto Medical School, University of São Paulo, Ribeirao Preto 14049-900, Brazil
| | - Denny Marcos Garcia
- Department of Ophthalmology, Otorhinolaryngology and Head and Neck Surgery, Ribeirão Preto Medical School, University of São Paulo, Ribeirao Preto 14049-900, Brazil
| | - Eduardo Melani Rocha
- Department of Ophthalmology, Otorhinolaryngology and Head and Neck Surgery, Ribeirão Preto Medical School, University of São Paulo, Ribeirao Preto 14049-900, Brazil
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Poitras T, Zochodne DW. Unleashing Intrinsic Growth Pathways in Regenerating Peripheral Neurons. Int J Mol Sci 2022; 23:13566. [PMID: 36362354 PMCID: PMC9654452 DOI: 10.3390/ijms232113566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 10/24/2022] [Accepted: 10/28/2022] [Indexed: 10/17/2023] Open
Abstract
Common mechanisms of peripheral axon regeneration are recruited following diverse forms of damage to peripheral nerve axons. Whether the injury is traumatic or disease related neuropathy, reconnection of axons to their targets is required to restore function. Supporting peripheral axon regrowth, while not yet available in clinics, might be accomplished from several directions focusing on one or more of the complex stages of regrowth. Direct axon support, with follow on participation of supporting Schwann cells is one approach, emphasized in this review. However alternative approaches might include direct support of Schwann cells that instruct axons to regrow, manipulation of the inflammatory milieu to prevent ongoing bystander axon damage, or use of inflammatory cytokines as growth factors. Axons may be supported by a growing list of growth factors, extending well beyond the classical neurotrophin family. The understanding of growth factor roles continues to expand but their impact experimentally and in humans has faced serious limitations. The downstream signaling pathways that impact neuron growth have been exploited less frequently in regeneration models and rarely in human work, despite their promise and potency. Here we review the major regenerative signaling cascades that are known to influence adult peripheral axon regeneration. Within these pathways there are major checkpoints or roadblocks that normally check unwanted growth, but are an impediment to robust growth after injury. Several molecular roadblocks, overlapping with tumour suppressor systems in oncology, operate at the level of the perikarya. They have impacts on overall neuron plasticity and growth. A second approach targets proteins that largely operate at growth cones. Addressing both sites might offer synergistic benefits to regrowing neurons. This review emphasizes intrinsic aspects of adult peripheral axon regeneration, emphasizing several molecular barriers to regrowth that have been studied in our laboratory.
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Affiliation(s)
| | - Douglas W. Zochodne
- Neuroscience and Mental Health Institute, Division of Neurology, Department of Medicine, University of Alberta, Edmonton, AB T6G 2G3, Canada
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Cosmo E, Midena G, Frizziero L, Bruno M, Cecere M, Midena E. Corneal Confocal Microscopy as a Quantitative Imaging Biomarker of Diabetic Peripheral Neuropathy: A Review. J Clin Med 2022; 11:jcm11175130. [PMID: 36079060 PMCID: PMC9457345 DOI: 10.3390/jcm11175130] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/26/2022] [Accepted: 08/29/2022] [Indexed: 11/16/2022] Open
Abstract
Distal symmetric polyneuropathy (DPN), particularly chronic sensorimotor DPN, represents one of the most frequent complications of diabetes, affecting 50% of diabetic patients and causing an enormous financial burden. Whilst diagnostic methods exist to detect and monitor this condition, they have significant limitations, mainly due to their high subjectivity, invasiveness, and non-repeatability. Corneal confocal microscopy (CCM) is an in vivo, non-invasive, and reproducible diagnostic technique for the study of all corneal layers including the sub-basal nerve plexus, which represents part of the peripheral nervous system. We reviewed the current literature on the use of CCM as an instrument in the assessment of diabetic patients, particularly focusing on its role in the study of sub-basal nerve plexus alterations as a marker of DPN. CCM has been demonstrated to be a valid in vivo tool to detect early sub-basal nerve plexus damage in adult and pediatric diabetic patients, correlating with the severity of DPN. Despite its great potential, CCM has still limited application in daily clinical practice, and more efforts still need to be made to allow the dissemination of this technique among doctors taking care of diabetic patients.
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Affiliation(s)
| | | | - Luisa Frizziero
- Department of Neuroscience-Ophthalmology, University of Padova, 35128 Padova, Italy
| | | | | | - Edoardo Midena
- IRCCS—Fondazione Bietti, 00198 Rome, Italy
- Department of Neuroscience-Ophthalmology, University of Padova, 35128 Padova, Italy
- Correspondence: ; Tel.: +39-049-821-2110
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Jolivalt CG, Han MM, Nguyen A, Desmond F, Alves Jesus CH, Vasconselos DC, Pedneault A, Sandlin N, Dunne-Cerami S, Frizzi KE, Calcutt NA. Using Corneal Confocal Microscopy to Identify Therapeutic Agents for Diabetic Neuropathy. J Clin Med 2022; 11:jcm11092307. [PMID: 35566433 PMCID: PMC9104226 DOI: 10.3390/jcm11092307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 04/19/2022] [Accepted: 04/19/2022] [Indexed: 02/04/2023] Open
Abstract
Corneal confocal microscopy (CCM) is emerging as a tool for identifying small fiber neuropathy in both peripheral neuropathies and neurodegenerative disease of the central nervous system (CNS). The value of corneal nerves as biomarkers for efficacy of clinical interventions against small fiber neuropathy and neurodegenerative disease is less clear but may be supported by preclinical studies of investigational agents. We, therefore, used diverse investigational agents to assess concordance of efficacy against corneal nerve loss and peripheral neuropathy in a mouse model of diabetes. Ocular delivery of the peptides ciliary neurotrophic factor (CNTF) or the glucagon-like peptide (GLP) analog exendin-4, both of which prevent diabetic neuropathy when given systemically, restored corneal nerve density within 2 weeks. Similarly, ocular delivery of the muscarinic receptor antagonist cyclopentolate protected corneal nerve density while concurrently reversing indices of systemic peripheral neuropathy. Conversely, systemic delivery of the muscarinic antagonist glycopyrrolate, but not gallamine, prevented multiple indices of systemic peripheral neuropathy and concurrently protected against corneal nerve loss. These data highlight the potential for use of corneal nerve quantification by confocal microscopy as a bridging assay between in vitro and whole animal assays in drug development programs for neuroprotectants and support its use as a biomarker of efficacy against peripheral neuropathy.
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11
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Zhou T, Lee A, Lo ACY, Kwok JSWJ. Diabetic Corneal Neuropathy: Pathogenic Mechanisms and Therapeutic Strategies. Front Pharmacol 2022; 13:816062. [PMID: 35281903 PMCID: PMC8905431 DOI: 10.3389/fphar.2022.816062] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/27/2022] [Indexed: 12/27/2022] Open
Abstract
Diabetes mellitus (DM) is a major global public health problem that can cause complications such as diabetic retinopathy, diabetic neuropathy, and diabetic nephropathy. Besides the reporting of reduction in corneal nerve density and decrease in corneal sensitivity in diabetic patients, there may be a subsequent result in delayed corneal wound healing and increased corneal infections. Despite being a potential cause of blindness, these corneal nerve changes have not gained enough attention. It has been proposed that corneal nerve changes may be an indicator for diabetic neuropathy, which can provide a window for early diagnosis and treatment. In this review, the authors aimed to give an overview of the relationship between corneal nerves and diabetic neuropathy as well as the underlying pathophysiological mechanisms of corneal nerve fiber changes caused by DM for improved prediction and prevention of diabetic neuropathy. In addition, the authors summarized current and novel therapeutic methods for delayed corneal wound healing, nerve protection and regeneration in the diabetic cornea.
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Affiliation(s)
- Ting Zhou
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Allie Lee
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Amy Cheuk Yin Lo
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Jeremy Sze Wai John Kwok
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
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12
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Carmichael J, Fadavi H, Tavakoli M. Neurodegeneration of the cornea and retina in patients with type 1 diabetes without clinical evidence of diabetic retinopathy. Front Endocrinol (Lausanne) 2022; 13:790255. [PMID: 36277683 PMCID: PMC9581164 DOI: 10.3389/fendo.2022.790255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 09/13/2022] [Indexed: 11/13/2022] Open
Abstract
AIM Diabetic retinopathy (DR) is widely considered the earliest and most common microvascular complication of diabetes. However, recent studies have shown that retinal nerve fiber layer and corneal nerve abnormalities may be present in diabetic patients without retinopathy. This preliminary study aimed to establish if structural and functional changes in the nerve fiber layer of the retina and cornea occur in patients with type 1 diabetes (T1DM) without retinopathy. METHODS Twenty patients with T1DM, without clinical evidence of retinopathy (Age: 47.0 ± 2.5 years; Duration diabetes: 27.0 ± 3 years) and 15 age-matched healthy control subjects underwent detailed medical neurological examinations. Ophthalmic examinations using Spectral Domain Optical coherence tomography (SD-OCT), Standard Automated Perimetry (SAP), Flicker Defined Form High Edge Perimetry (FDF), Corneal Confocal Microscopy (CCM) and Non-contact corneal Aesthesiometry (NCCA) were performed to quantify the structure and function of the nerves in the retina and cornea, respectively. RESULTS At the structural level, retinal nerve fiber layer thickness (RNFL) was significantly reduced in the superior nasal (p=0.001) and inferior temporal (p=0.004) sectors, in diabetic patients. Retinal ganglion layer function was reduced in the patient group when assessed using Flicker Defined Form Perimetry (FDF), but this was not significant. The function of the cornea assessed by corneal sensitivity, using a non-contact corneal aesthesiometer (NCCA), was significantly reduced (p=0.001). Structural assessment of corneal nerves using corneal confocal microscopy (CCM) showed reduction at corneal nerve fiber density (CNFD) (p=0.01), branch density (CNBD) (p=0.006) and length (CNFL) (p=0.01) in patients with diabetes. Compared to control subjects, the percentage of abnormality in patients with T1DM for RNFL was 32% while the FDF was abnormal in 61% of patients. Corneal abnormality was observed in 47% for NCCA, 28% for CNFD, and 17% for CNFL. There was no correlation between neuronal damage in the retina and cornea. CONCLUSIONS Neuronal abnormalities were observed in both the retina and cornea of diabetic patients without evidence of retinopathy. The prevalence of structural and functional changes was higher in the retina compared to the cornea. This preliminary study suggests that structural neuronal changes may occur in parallel and correlate with functional changes. The assessment of corneal and retinal nerve structure may be clinically useful for detecting and monitoring the earliest stages of diabetic microvascular abnormalities.
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Affiliation(s)
- Josie Carmichael
- Exeter Centre of Excellence for Diabetes Research, National Institute for Health and Care Research (NIHR) Exeter Clinical Research Facility, University of Exeter Medical School, Exeter, United Kingdom
| | - Hassan Fadavi
- Peripheral Neuropathy Group, Imperial College, London, United Kingdom
| | - Mitra Tavakoli
- Exeter Centre of Excellence for Diabetes Research, National Institute for Health and Care Research (NIHR) Exeter Clinical Research Facility, University of Exeter Medical School, Exeter, United Kingdom
- *Correspondence: Mitra Tavakoli,
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13
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Jolivalt CG, Aghanoori MR, Navarro-Diaz MC, Han MM, Sanchez G, Guernsey L, Quach D, Johe K, Fernyhough P, Calcutt NA. Enhancement of Mitochondrial Function by the Neurogenic Molecule NSI-189 Accompanies Reversal of Peripheral Neuropathy and Memory Impairment in a Rat Model of Type 2 Diabetes. J Diabetes Res 2022; 2022:8566970. [PMID: 35967127 PMCID: PMC9372526 DOI: 10.1155/2022/8566970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 06/17/2022] [Indexed: 12/03/2022] Open
Abstract
AIMS Mitochondrial dysfunction contributes to many forms of peripheral and central nervous system degeneration. Therapies that protect mitochondrial number and function have the potential to impact the progression of conditions such as diabetic neuropathy. We therefore assessed indices of mitochondrial function in dorsal root ganglia (DRG) and brain cortex of the Zucker diabetic fatty (ZDF) rat model of type 2 diabetes and tested the therapeutic impact of a neurogenic compound, NSI-189, on both mitochondrial function and indices of peripheral and central neurological dysfunction. MATERIALS AND METHODS ZDF rats were maintained for 16 weeks of untreated diabetes before the start of oral treatment with NSI-189 for an additional 16 weeks. Nerve conduction velocity, sensitivity to tactile and thermal stimuli, and behavioral assays of cognitive function were assessed monthly. AMP-activated protein kinase (AMPK) phosphorylation, mitochondrial protein levels, and respiratory complex activities were assessed in the DRG and brain cortex after 16 weeks of treatment with NSI-189. RESULTS Treatment with NSI-189 selectively elevated the expression of protein subunits of complexes III and V and activities of respiratory complexes I and IV in the brain cortex, and this was accompanied by amelioration of impaired memory function and plasticity. In the sensory ganglia of ZDF rats, loss of AMPK activity was ameliorated by NSI-189, and this was accompanied by reversal of multiple indices of peripheral neuropathy. CONCLUSIONS Efficacy of NSI-189 against dysfunction of the CNS and PNS function in type 2 diabetic rats was accompanied by improvement of mitochondrial function. NSI-189 exhibited actions at different levels of mitochondrial regulation in central and peripheral tissues.
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Affiliation(s)
- C. G. Jolivalt
- University of California San Diego, Department of Pathology, La Jolla, CA, USA
| | - M. R. Aghanoori
- Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada
| | - M. C. Navarro-Diaz
- University of California San Diego, Department of Pathology, La Jolla, CA, USA
| | - M. M. Han
- University of California San Diego, Department of Pathology, La Jolla, CA, USA
| | - G. Sanchez
- University of California San Diego, Department of Pathology, La Jolla, CA, USA
| | - L. Guernsey
- University of California San Diego, Department of Pathology, La Jolla, CA, USA
| | - D. Quach
- Neuralstem Inc., Germantown, MD, USA
| | - K. Johe
- Neuralstem Inc., Germantown, MD, USA
| | - P. Fernyhough
- Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada
| | - N. A. Calcutt
- University of California San Diego, Department of Pathology, La Jolla, CA, USA
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14
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Topical Insulin-Utility and Results in Refractory Neurotrophic Keratopathy in Stages 2 and 3. Cornea 2021; 41:990-994. [PMID: 34483270 DOI: 10.1097/ico.0000000000002858] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Accepted: 07/08/2021] [Indexed: 11/26/2022]
Abstract
PURPOSE The purpose of this study was to evaluate the clinical outcome of patients with refractory neurotrophic keratopathy (NK) in stages 2 and 3 treated with topical insulin. METHODS Retrospective analysis of eyes with NK in stages 2 and 3 refractory to standard medical and/or surgical treatment which were treated with topical insulin (1 unit per mL). This treatment was applied 4 times per day and was continued until the persistent epithelial defect (PED) or ulcer resolved. The primary outcome of the study was the complete reepithelialization of the PED or persistent ulcer. "Best-corrected visual acuity" pretreatment and posttreatment, "days until complete reepithelialization" data, and anterior segment photographs were obtained. Outcome measures were compared before and after treatment in both groups using paired and independent samples t tests. RESULTS Twenty-one eyes were included in this study, and 90% achieved complete reepithelialization of the PED and/or persistent ulcer within 7 to 45 days of follow-up. The mean number of days until complete reepithelialization was significantly lower in NK stage 2 (18 ± 9 days) when compared with NK stage 3 (29 ± 11 days) (P = 0.025). The best-corrected visual acuity improved significantly in both NK stage 2 (P < 0.001) and NK stage 3 (P = 0.004). No side effects were reported during the follow-up. CONCLUSIONS Our results suggest that topical insulin drops may be an effective therapeutic in refractory NK. This therapy may prove extremely useful because of its low cost and high accessibility.
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15
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Petropoulos IN, Ponirakis G, Ferdousi M, Azmi S, Kalteniece A, Khan A, Gad H, Bashir B, Marshall A, Boulton AJM, Soran H, Malik RA. Corneal Confocal Microscopy: A Biomarker for Diabetic Peripheral Neuropathy. Clin Ther 2021; 43:1457-1475. [PMID: 33965237 DOI: 10.1016/j.clinthera.2021.04.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/05/2021] [Accepted: 04/08/2021] [Indexed: 02/08/2023]
Abstract
PURPOSE Diagnosing early diabetic peripheral neuropathy remains a challenge due to deficiencies in currently advocated end points. The cornea is densely innervated with small sensory fibers, which are structurally and functionally comparable to intraepidermal nerve fibers. Corneal confocal microscopy is a method for rapid, noninvasive scanning of the living cornea with high resolution and magnification. METHODS This narrative review presents the framework for the development of biomarkers and the literature on the use and adoption of corneal confocal microscopy as an objective, diagnostic biomarker in experimental and clinical studies of diabetic peripheral neuropathy. A search was performed on PubMed and Google Scholar based on the terms "corneal confocal microscopy," "diabetic neuropathy," "corneal sensitivity," and "clinical trials." FINDINGS A substantial body of evidence underpins the thesis that corneal nerve loss predicts incident neuropathy and progresses with the severity of diabetic peripheral neuropathy. Corneal confocal microscopy also identifies early corneal nerve regeneration, strongly arguing for its inclusion as a surrogate end point in clinical trials of disease-modifying therapies. IMPLICATIONS There are sufficient diagnostic and prospective validation studies to fulfill the US Food and Drug Administration criteria for a biomarker to support the inclusion of corneal confocal microscopy as a primary end point in clinical trials of disease-modifying therapies in diabetic neuropathy.
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Affiliation(s)
| | | | - Maryam Ferdousi
- Faculty of Biology, Medicine and Health, University of Manchester, Cardiovascular Trials Unit, Manchester University NHS Foundation Trust, Manchester, United Kingdom
| | - Shazli Azmi
- Faculty of Biology, Medicine and Health, University of Manchester, Cardiovascular Trials Unit, Manchester University NHS Foundation Trust, Manchester, United Kingdom; Centre for Diabetes, Endocrinology and Metabolism, Manchester University NHS Foundation Trust, Manchester, United Kingdom
| | - Alise Kalteniece
- Faculty of Biology, Medicine and Health, University of Manchester, Cardiovascular Trials Unit, Manchester University NHS Foundation Trust, Manchester, United Kingdom
| | - Adnan Khan
- Research Division, Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Hoda Gad
- Research Division, Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Bilal Bashir
- Centre for Diabetes, Endocrinology and Metabolism, Manchester University NHS Foundation Trust, Manchester, United Kingdom
| | - Andrew Marshall
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom; Clinical Neurophysiology, The Walton Centre, Liverpool, United Kingdom; Division of Neuroscience and Experimental Psychology, Faculty of Medical and Human Sciences, University of Manchester, Manchester, United Kingdom
| | - Andrew J M Boulton
- Faculty of Biology, Medicine and Health, University of Manchester, Cardiovascular Trials Unit, Manchester University NHS Foundation Trust, Manchester, United Kingdom; Centre for Diabetes, Endocrinology and Metabolism, Manchester University NHS Foundation Trust, Manchester, United Kingdom
| | - Handrean Soran
- Faculty of Biology, Medicine and Health, University of Manchester, Cardiovascular Trials Unit, Manchester University NHS Foundation Trust, Manchester, United Kingdom
| | - Rayaz A Malik
- Research Division, Weill Cornell Medicine-Qatar, Doha, Qatar; Faculty of Biology, Medicine and Health, University of Manchester, Cardiovascular Trials Unit, Manchester University NHS Foundation Trust, Manchester, United Kingdom.
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16
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Shah R, Amador C, Tormanen K, Ghiam S, Saghizadeh M, Arumugaswami V, Kumar A, Kramerov AA, Ljubimov AV. Systemic diseases and the cornea. Exp Eye Res 2021; 204:108455. [PMID: 33485845 PMCID: PMC7946758 DOI: 10.1016/j.exer.2021.108455] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/11/2021] [Accepted: 01/12/2021] [Indexed: 01/08/2023]
Abstract
There is a number of systemic diseases affecting the cornea. These include endocrine disorders (diabetes, Graves' disease, Addison's disease, hyperparathyroidism), infections with viruses (SARS-CoV-2, herpes simplex, varicella zoster, HTLV-1, Epstein-Barr virus) and bacteria (tuberculosis, syphilis and Pseudomonas aeruginosa), autoimmune and inflammatory diseases (rheumatoid arthritis, Sjögren's syndrome, lupus erythematosus, gout, atopic and vernal keratoconjunctivitis, multiple sclerosis, granulomatosis with polyangiitis, sarcoidosis, Cogan's syndrome, immunobullous diseases), corneal deposit disorders (Wilson's disease, cystinosis, Fabry disease, Meretoja's syndrome, mucopolysaccharidosis, hyperlipoproteinemia), and genetic disorders (aniridia, Ehlers-Danlos syndromes, Marfan syndrome). Corneal manifestations often provide an insight to underlying systemic diseases and can act as the first indicator of an undiagnosed systemic condition. Routine eye exams can bring attention to potentially life-threatening illnesses. In this review, we provide a fairly detailed overview of the pathologic changes in the cornea described in various systemic diseases and also discuss underlying molecular mechanisms, as well as current and emerging treatments.
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Affiliation(s)
- Ruchi Shah
- Eye Program, Board of Governors Regenerative Medicine Institute, Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
| | - Cynthia Amador
- Eye Program, Board of Governors Regenerative Medicine Institute, Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Kati Tormanen
- Center for Neurobiology and Vaccine Development, Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Sean Ghiam
- Sackler School of Medicine, New York State/American Program of Tel Aviv University, Tel Aviv, Israel
| | - Mehrnoosh Saghizadeh
- Eye Program, Board of Governors Regenerative Medicine Institute, Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA; Departments of Molecular and Medical Pharmacology, Medicine, and Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Vaithi Arumugaswami
- Departments of Molecular and Medical Pharmacology, Medicine, and Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Ashok Kumar
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University, Detroit, MI, USA
| | - Andrei A Kramerov
- Eye Program, Board of Governors Regenerative Medicine Institute, Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Alexander V Ljubimov
- Eye Program, Board of Governors Regenerative Medicine Institute, Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA; Departments of Molecular and Medical Pharmacology, Medicine, and Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA.
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Abstract
Neuropathy is a common complication of long-term diabetes that impairs quality of life by producing pain, sensory loss and limb amputation. The presence of neuropathy in both insulin-deficient (type 1) and insulin resistant (type 2) diabetes along with the slowing of progression of neuropathy by improved glycemic control in type 1 diabetes has caused the majority of preclinical and clinical investigations to focus on hyperglycemia as the initiating pathogenic lesion. Studies in animal models of diabetes have identified multiple plausible mechanisms of glucotoxicity to the nervous system including post-translational modification of proteins by glucose and increased glucose metabolism by aldose reductase, glycolysis and other catabolic pathways. However, it is becoming increasingly apparent that factors not necessarily downstream of hyperglycemia can also contribute to the incidence, progression and severity of neuropathy and neuropathic pain. For example, peripheral nerve contains insulin receptors that transduce the neurotrophic and neurosupportive properties of insulin, independent of systemic glucose regulation, while the detection of neuropathy and neuropathic pain in patients with metabolic syndrome and failure of improved glycemic control to protect against neuropathy in cohorts of type 2 diabetic patients has placed a focus on the pathogenic role of dyslipidemia. This review provides an overview of current understanding of potential initiating lesions for diabetic neuropathy and the multiple downstream mechanisms identified in cell and animal models of diabetes that may contribute to the pathogenesis of diabetic neuropathy and neuropathic pain.
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18
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Sebbag L, Thomasy SM, Leland A, Mukai M, Kim S, Maggs DJ. Altered Corneal Innervation and Ocular Surface Homeostasis in FHV-1-Exposed Cats: A Preliminary Study Suggesting Metaherpetic Disease. Front Vet Sci 2021; 7:580414. [PMID: 33575276 PMCID: PMC7870478 DOI: 10.3389/fvets.2020.580414] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 12/31/2020] [Indexed: 12/18/2022] Open
Abstract
Metaherpetic disease is recognized in humans affected by herpes simplex virus-1 but is not reported in cats affected by feline herpesvirus-1 (FHV-1) despite the high prevalence of herpetic disease in this species and strong similarities in viral biology between alphaherpesviruses of humans and cats. This preliminary work evaluated cats naïve to FHV-1 (n = 9 cats, 18 eyes; control population) and cats naturally exposed to FHV-1 (n = 4 cats, 7 eyes), as confirmed by serologic testing and review of medical records. Antemortem assessment included clinical scoring, blink rate, corneal aesthesiometry, tear film breakup time (TFBUT), and Schirmer tear test-1 (STT-1) with or without the nasolacrimal reflex. Post-mortem assessment involved confocal microscopy of the corneas and evaluation of corneal nerves with ImageJ. Groups were compared with Student's t-tests and results are presented as mean ± standard deviation. Compared to control, herpetic cats had significantly higher (P ≤ 0.010) clinical scores (0.2 ± 0.4 vs. 4.6 ± 2.8) and response to nasolacrimal stimulation (7.8 ± 10.8% vs. 104.8 ± 151.1%), significantly lower (P < 0.001) corneal sensitivity (2.9 ± 0.6 cm vs. 1.4 ± 0.9 cm), STT-1 (20.8 ± 2.6 mm/min vs. 10.6 ± 6.0 mm/min), TFBUT (12.1 ± 2.0 s vs. 7.1 ± 2.9 s), and non-significantly lower blink rate (3.0 ± 1.5 blinks/min vs. 2.7 ± 0.5 blinks/min; P = 0.751). All parameters evaluated for corneal nerves (e.g., nerve fiber length, branching, occupancy) were notably but not significantly lower in herpetic vs. control cats (P ≥ 0.268). In sum, cats exposed to FHV-1 had signs suggestive of corneal hypoesthesia and quantitative/qualitative tear film deficiencies when compared to cats naïve to the virus. It is possible these are signs of metaherpetic disease as reported in other species.
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Affiliation(s)
- Lionel Sebbag
- Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Rehovot, Israel.,Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States.,Department of Veterinary Clinical Sciences, Iowa State University College of Veterinary Medicine, Ames, IA, United States
| | - Sara M Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Adriana Leland
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Madison Mukai
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Soohyun Kim
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - David J Maggs
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
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Marquez A, Guernsey LS, Frizzi KE, Cundiff M, Constantino I, Muttalib N, Arenas F, Zhou X, Lim SH, Ferdousi M, Ponirakis G, Silverdale M, Kobylecki C, Jones M, Marshall A, Malik RA, Jolivalt CG. Tau associated peripheral and central neurodegeneration: Identification of an early imaging marker for tauopathy. Neurobiol Dis 2021; 151:105273. [PMID: 33482356 DOI: 10.1016/j.nbd.2021.105273] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 01/15/2021] [Indexed: 01/29/2023] Open
Abstract
Pathological hyperphosphorylated tau is a key feature of Alzheimer's disease (AD) and Frontotemporal dementia (FTD). Using transgenic mice overexpressing human non-mutated tau (htau mice), we assessed the contribution of tau to peripheral and central neurodegeneration. Indices of peripheral small and large fiber neuropathy and learning and memory performances were assessed at 3 and 6 months of age. Overexpression of human tau is associated with peripheral neuropathy at 6 months of age. Our study also provides evidence that non-mutated tau hyperphosphorylation plays a critical role in memory deficits. In addition, htau mice had reduced stromal corneal nerve length with preservation of sub-basal corneal nerves, consistent with a somatofugal degeneration. Corneal nerve degeneration occurred prior to any cognitive deficits and peripheral neuropathy. Stromal corneal nerve loss was observed in patients with FTD but not AD. Corneal confocal microscopy may be used to identify early neurodegeneration and differentiate FTD from AD.
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Affiliation(s)
| | - Lucie S Guernsey
- Department of Pathology, University of California San Diego, USA
| | - Katie E Frizzi
- Department of Pathology, University of California San Diego, USA
| | - Morgan Cundiff
- Department of Pathology, University of California San Diego, USA
| | | | - Nabeel Muttalib
- Department of Pathology, University of California San Diego, USA
| | - Fernanda Arenas
- Department of Pathology, University of California San Diego, USA
| | - Xiajun Zhou
- Department of Pathology, University of California San Diego, USA
| | - Sze Hway Lim
- Department of Neurology, Manchester Centre for Clinical Neurosciences, Salford Royal NHS Foundation Trust, Salford, UK
| | - Maryam Ferdousi
- Institute of Cardiovascular Sciences, University of Manchester and Central Manchester NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | | | - Monty Silverdale
- Department of Neurology, Manchester Centre for Clinical Neurosciences, Salford Royal NHS Foundation Trust, Salford, UK; Manchester Academic Health Sciences Centre, University of Manchester, UK
| | - Christopher Kobylecki
- Department of Neurology, Manchester Centre for Clinical Neurosciences, Salford Royal NHS Foundation Trust, Salford, UK; Manchester Academic Health Sciences Centre, University of Manchester, UK
| | - Matthew Jones
- Department of Neurology, Manchester Centre for Clinical Neurosciences, Salford Royal NHS Foundation Trust, Salford, UK
| | - Andrew Marshall
- Department of Clinical Neurophysiology, Salford Royal Hospital, National Health Service Foundation Trust, Institute of Brain, Behaviour and Mental Health, University of Manchester, Manchester, UK
| | - Rayaz A Malik
- Department of Medicine, Weill Cornell Medicine-Qatar, Doha, Qatar and Institute of Cardiovascular Science, University of Manchester, Manchester, UK
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20
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Jin HY, Moon SS, Calcutt NA. Lost in Translation? Measuring Diabetic Neuropathy in Humans and Animals. Diabetes Metab J 2021; 45:27-42. [PMID: 33307618 PMCID: PMC7850880 DOI: 10.4093/dmj.2020.0216] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 10/06/2020] [Indexed: 12/21/2022] Open
Abstract
The worldwide diabetes epidemic is estimated to currently afflict almost 500 million persons. Long-term diabetes damages multiple organ systems with the blood vessels, eyes, kidneys and nervous systems being particularly vulnerable. These complications of diabetes reduce lifespan, impede quality of life and impose a huge social and economic burden on both the individual and society. Peripheral neuropathy is a debilitating complication that will impact over half of all persons with diabetes. There is no treatment for diabetic neuropathy and a disturbingly long history of therapeutic approaches showing promise in preclinical studies but failing to translate to the clinic. These failures have prompted re-examination of both the animal models and clinical trial design. This review focuses on the functional and structural parameters used as indices of peripheral neuropathy in preclinical and clinical studies and the extent to which they share a common pathogenesis and presentation. Nerve conduction studies in large myelinated fibers have long been the mainstay of preclinical efficacy screening programs and clinical trials, supplemented by quantitative sensory tests. However, a more refined approach is emerging that incorporates measures of small fiber density in the skin and cornea alongside these traditional assays at both preclinical and clinical phases.
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Affiliation(s)
- Heung Yong Jin
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Jeonbuk National University Medical School, Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju,
USA
| | - Seong-Su Moon
- Department of Internal Medicine, Dongguk University College of Medicine, Gyeongju,
USA
- Division of Endocrinology, Department of Internal Medicine, Nazareth General Hospital, Daegu,
Korea,
USA
| | - Nigel A. Calcutt
- Department of Pathology, University of California San Diego, La Jolla, CA,
USA
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21
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Aliabadi DA, Moradian N, Rahmanian E, Mohammadi M. Prevalence of neuropathy in patients with type 2 diabetes in Iran : A systematic review and meta-analysis. Wien Klin Wochenschr 2020; 133:222-228. [PMID: 33336262 DOI: 10.1007/s00508-020-01784-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 11/18/2020] [Indexed: 11/24/2022]
Abstract
BACKGROUND Diabetic neuropathy is one of the most common complications of diabetes, which leads to amputation and significant disability in patients. Studies conducted in this field show different prevalences and inconsistencies in the country. This study attempts to determine the overall prevalence of neuropathy in patients with type 2 diabetes in Iran with a meta-analysis. METHODS The present study was conducted using a meta-analysis method from January 2000 to December 2018. The papers related to the study subject were obtained from searching Scopus, ScienceDirect, Magiran, Barakat Knowledge Network, SID, Medline (PubMed), and Google Scholar databases. The heterogeneity of studies was examined using I2 index and the data were analyzed using the software Comprehensive Meta-Analysis (version 3, Biostat, Englewood, NJ, USA). RESULTS The results of the systematic review showed regional differences in the prevalence of neuropathy in Iran. According to the meta-analysis and review of 10 studies and 2992 individuals between the ages of 5 years and 86 years, the overall prevalence of neuropathy in type 2 diabetes patients in Iran was 56.5% (95% confidence interval, CI 42.8-69.3%). The highest prevalence of neuropathy in type 2 diabetic patients was found in Mashhad with 87.2% (95% CI 77.9-92.3%) in 2012 and the lowest prevalence of neuropathy in type 2 diabetic patients was found in Ahvaz with 22.7% (95% CI 18.5-27.6%) in 2014. With the increase in years of research, the prevalence of neuropathy in type 2 diabetes in Iran was reduced, with statistically significant differences (P < 0.05). CONCLUSION Considering the high prevalence of neuropathy in patients with type 2 diabetes in the country, it is essential that health policy makers take effective measures to reduce this disease in diabetes patients.
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Affiliation(s)
- Dariush Afshari Aliabadi
- Department of Neurology, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Nasrin Moradian
- Department of Neurology, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Elham Rahmanian
- Department of Nursing, School of Nursing and Midwifery, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Masoud Mohammadi
- Department of Nursing, School of Nursing and Midwifery, Kermanshah University of Medical Sciences, Kermanshah, Iran.
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Yap KH, Yee GS, Candasamy M, Tan SC, Md S, Abdul Majeed AB, Bhattamisra SK. Catalpol Ameliorates Insulin Sensitivity and Mitochondrial Respiration in Skeletal Muscle of Type-2 Diabetic Mice Through Insulin Signaling Pathway and AMPK/SIRT1/PGC-1α/PPAR-γ Activation. Biomolecules 2020; 10:biom10101360. [PMID: 32987623 PMCID: PMC7598587 DOI: 10.3390/biom10101360] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 09/06/2020] [Accepted: 09/09/2020] [Indexed: 12/14/2022] Open
Abstract
Catalpol was tested for various disorders including diabetes mellitus. Numerous molecular mechanisms have emerged supporting its biological effects but with little information towards its insulin sensitizing effect. In this study, we have investigated its effect on skeletal muscle mitochondrial respiration and insulin signaling pathway. Type-2 diabetes (T2DM) was induced in male C57BL/6 by a high fat diet (60% Kcal) and streptozotocin (50 mg/kg, i.p.). Diabetic mice were orally administered with catalpol (100 and 200 mg/kg), metformin (200 mg/kg), and saline for four weeks. Fasting blood glucose (FBG), HbA1c, plasma insulin, oral glucose tolerance test (OGTT), insulin tolerance test (ITT), oxygen consumption rate, gene (IRS-1, Akt, PI3k, AMPK, GLUT4, and PGC-1α) and protein (AMPK, GLUT4, and PPAR-γ) expression in muscle were measured. Catalpol (200 mg/kg) significantly (p < 0.05) reduced the FBG, HbA1C, HOMA_IR index, and AUC of OGTT whereas, improved the ITT slope. Gene (IRS-1, Akt, PI3k, GLUT4, AMPK, and PGC-1α) and protein (AMPK, p-AMPK, PPAR-γ and GLUT4) expressions, as well as augmented state-3 respiration, oxygen consumption rate, and citrate synthase activity in muscle was observed in catalpol treated mice. The antidiabetic activity of catalpol is credited with a marked improvement in insulin sensitivity and mitochondrial respiration through the insulin signaling pathway and AMPK/SIRT1/PGC-1α/PPAR-γ activation in the skeletal muscle of T2DM mice.
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Affiliation(s)
- Kah Heng Yap
- School of Postgraduate Studies, International Medical University, Bukit Jalil, Kuala Lumpur 57000, Malaysia; (K.H.Y.); (S.C.T.)
| | - Gan Sook Yee
- Department of Life Sciences, School of Pharmacy, International Medical University, Bukit Jalil, Kuala Lumpur 57000, Malaysia; (G.S.Y.); (M.C.)
| | - Mayuren Candasamy
- Department of Life Sciences, School of Pharmacy, International Medical University, Bukit Jalil, Kuala Lumpur 57000, Malaysia; (G.S.Y.); (M.C.)
| | - Swee Ching Tan
- School of Postgraduate Studies, International Medical University, Bukit Jalil, Kuala Lumpur 57000, Malaysia; (K.H.Y.); (S.C.T.)
| | - Shadab Md
- Department of Pharmaceutics, Faculty of Pharmacy, King Abdulaziz University, Jeddah 21589, Saudi Arabia;
| | - Abu Bakar Abdul Majeed
- Universiti Teknologi MARA, Sungai Buloh-Selayang Medical-Dental Campus, Jalan Hospital, Sungai Buloh, Selangor 47000, Malaysia;
| | - Subrat Kumar Bhattamisra
- Department of Life Sciences, School of Pharmacy, International Medical University, Bukit Jalil, Kuala Lumpur 57000, Malaysia; (G.S.Y.); (M.C.)
- Correspondence: or ; Tel.: +60-3-27317310; Fax: +60-3-86567229
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23
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Corneal Neurotization and Novel Medical Therapies for Neurotrophic Keratopathy. CURRENT OPHTHALMOLOGY REPORTS 2020. [DOI: 10.1007/s40135-020-00254-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Abstract
Purpose of Review
Neurotrophic keratopathy (NK) is a degenerative corneal disease characterized by decreased corneal sensibility and impaired corneal healing. In this article, we review surgical techniques for corneal neurotization (CN) and novel medical therapies for the treatment of NK.
Recent Findings
In recent decades, there has been a paradigm shift in the treatment strategies for NK. New minimally invasive direct and indirect CN approaches have demonstrated efficacy at improving best-corrected visual acuity and central corneal sensation while decreasing surgical morbidity. In addition, several targeted medical therapies, such as recombinant human nerve growth factor (rhNGF), regenerating agents (RGTA), and nicergoline, have shown promise in improving corneal epithelial healing. Of these options, cenegermin (Oxervate®, Dompé), a topical biologic medication, has emerged as an approved medical treatment for moderate to severe NK.
Summary
NK is a challenging condition caused by alterations in corneal nerves, leading to impairment in sensory and trophic function with subsequent breakdown of the cornea. Conventional therapy for NK depends on the severity of disease and focuses primarily on protecting the ocular surface. In recent years, numerous CN techniques and novel medical treatments have been developed that aim to restore proper corneal innervation and promote ocular surface healing. Further studies are needed to better understand the long-term efficacy of these treatment options, their target populations, and the potential synergistic efficacy of combined medical and surgical treatments.
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Yang S, Zhang Y, Zhang Z, Dan J, Zhou Q, Wang X, Li W, Zhou L, Yang L, Xie L. Insulin Promotes Corneal Nerve Repair and Wound Healing in Type 1 Diabetic Mice by Enhancing Wnt/β-Catenin Signaling. THE AMERICAN JOURNAL OF PATHOLOGY 2020; 190:2237-2250. [PMID: 32858016 DOI: 10.1016/j.ajpath.2020.08.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 07/31/2020] [Accepted: 08/12/2020] [Indexed: 12/20/2022]
Abstract
The insulin and Wnt signaling pathways are involved in cell proliferation, tissue homeostasis, and tumorigenesis. However, their interrelationship in the pathophysiological process of diabetic corneal injury remains unclear. In this study, the role of insulin in the diabetic cornea was investigated in vitro, using cultured TKE2 cells and trigeminal ganglion neurons, and in vivo, by assessing corneal wound-healing responses in diabetic mice. A selective Wnt antagonist (XAV-939) and activator (BML-284) were used to regulate the interactions between insulin and the Wnt pathway. The results demonstrated that insulin promoted corneal epithelial wound healing and sensation recovery, whereas the expression of molecules involved in the Wnt/β-catenin pathway was also up-regulated in the injured corneal epithelium. However, XAV-939 limited the insulin-induced epithelial and corneal nerve repair. By contrast, BML-284 treatment promoted the healing of the corneal epithelium and corneal nerve repair in diabetic mice. These results indicate that insulin, via Wnt signaling, contributes to diabetic corneal epithelial wound healing and nerve injury recovery and is, therefore, a potential protective factor for diabetic corneal epithelial wounds and nerve injury.
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Affiliation(s)
- Shuo Yang
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Qingdao, China; Eye Center, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China; Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong, University of Science and Technology, Wuhan, China
| | - Yangyang Zhang
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Qingdao, China
| | - Zhaohua Zhang
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Qingdao, China
| | - Jing Dan
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Qingdao, China
| | - Qingjun Zhou
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Qingdao, China
| | - Xiaochuan Wang
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Qingdao, China
| | - Weina Li
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Qingdao, China
| | - Li Zhou
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Qingdao, China
| | - Lingling Yang
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Qingdao, China.
| | - Lixin Xie
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Qingdao, China.
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25
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Jolivalt CG, Frizzi KE, Han MM, Mota AJ, Guernsey LS, Kotra LP, Fernyhough P, Calcutt NA. Topical Delivery of Muscarinic Receptor Antagonists Prevents and Reverses Peripheral Neuropathy in Female Diabetic Mice. J Pharmacol Exp Ther 2020; 374:44-51. [PMID: 32327528 DOI: 10.1124/jpet.120.265447] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 04/20/2020] [Indexed: 02/06/2023] Open
Abstract
Muscarinic antagonists promote sensory neurite outgrowth in vitro and prevent and/or reverse multiple indices of peripheral neuropathy in rodent models of diabetes, chemotherapy-induced peripheral neuropathy, and HIV protein-induced neuropathy when delivered systemically. We measured plasma concentrations of the M1 receptor-selective muscarinic antagonist pirenzepine when delivered by subcutaneous injection, oral gavage, or topical application to the skin and investigated efficacy of topically delivered pirenzepine against indices of peripheral neuropathy in diabetic mice. Topical application of 2% pirenzepine to the paw resulted in plasma concentrations 6 hours postdelivery that approximated those previously shown to promote neurite outgrowth in vitro. Topical delivery of pirenzepine to the paw of mice with streptozotocin-induced diabetes dose-dependently (0.1%-10.0%) prevented tactile allodynia, thermal hypoalgesia, and loss of epidermal nerve fibers in the treated paw and attenuated large fiber motor nerve conduction slowing in the ipsilateral limb. Efficacy against some indices of neuropathy was also noted in the contralateral limb, indicating systemic effects following local treatment. Topical pirenzepine also reversed established paw heat hypoalgesia, whereas withdrawal of treatment resulted in a gradual decline in efficacy over 2-4 weeks. Efficacy of topical pirenzepine was muted when treatment was reduced from 5 to 3 or 1 day/wk. Similar local effects were noted with the nonselective muscarinic receptor antagonist atropine when applied either to the paw or to the eye. Topical delivery of muscarinic antagonists may serve as a practical therapeutic approach to treating diabetic and other peripheral neuropathies. SIGNIFICANCE STATEMENT: Muscarinic antagonist pirenzepine alleviates diabetic peripheral neuropathy when applied topically in mice.
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Affiliation(s)
- Corinne G Jolivalt
- Department of Pathology, University of California San Diego, San Diego, California (C.G.J., K.E.F., M.M.H., A.J.M., L.S.G., N.A.C.); Winsantor Inc. (K.E.F). Center for Molecular Design and Preformulations and Krembil Research Institute, University Health Network and Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada (L.P.K.); and Department of Pharmacology and Therapeutics and Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Center, University of Manitoba, Winnipeg, Manitoba, Canada (P.F.)
| | - Katie E Frizzi
- Department of Pathology, University of California San Diego, San Diego, California (C.G.J., K.E.F., M.M.H., A.J.M., L.S.G., N.A.C.); Winsantor Inc. (K.E.F). Center for Molecular Design and Preformulations and Krembil Research Institute, University Health Network and Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada (L.P.K.); and Department of Pharmacology and Therapeutics and Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Center, University of Manitoba, Winnipeg, Manitoba, Canada (P.F.)
| | - May Madi Han
- Department of Pathology, University of California San Diego, San Diego, California (C.G.J., K.E.F., M.M.H., A.J.M., L.S.G., N.A.C.); Winsantor Inc. (K.E.F). Center for Molecular Design and Preformulations and Krembil Research Institute, University Health Network and Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada (L.P.K.); and Department of Pharmacology and Therapeutics and Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Center, University of Manitoba, Winnipeg, Manitoba, Canada (P.F.)
| | - Andre J Mota
- Department of Pathology, University of California San Diego, San Diego, California (C.G.J., K.E.F., M.M.H., A.J.M., L.S.G., N.A.C.); Winsantor Inc. (K.E.F). Center for Molecular Design and Preformulations and Krembil Research Institute, University Health Network and Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada (L.P.K.); and Department of Pharmacology and Therapeutics and Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Center, University of Manitoba, Winnipeg, Manitoba, Canada (P.F.)
| | - Lucie S Guernsey
- Department of Pathology, University of California San Diego, San Diego, California (C.G.J., K.E.F., M.M.H., A.J.M., L.S.G., N.A.C.); Winsantor Inc. (K.E.F). Center for Molecular Design and Preformulations and Krembil Research Institute, University Health Network and Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada (L.P.K.); and Department of Pharmacology and Therapeutics and Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Center, University of Manitoba, Winnipeg, Manitoba, Canada (P.F.)
| | - Lakshmi P Kotra
- Department of Pathology, University of California San Diego, San Diego, California (C.G.J., K.E.F., M.M.H., A.J.M., L.S.G., N.A.C.); Winsantor Inc. (K.E.F). Center for Molecular Design and Preformulations and Krembil Research Institute, University Health Network and Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada (L.P.K.); and Department of Pharmacology and Therapeutics and Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Center, University of Manitoba, Winnipeg, Manitoba, Canada (P.F.)
| | - Paul Fernyhough
- Department of Pathology, University of California San Diego, San Diego, California (C.G.J., K.E.F., M.M.H., A.J.M., L.S.G., N.A.C.); Winsantor Inc. (K.E.F). Center for Molecular Design and Preformulations and Krembil Research Institute, University Health Network and Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada (L.P.K.); and Department of Pharmacology and Therapeutics and Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Center, University of Manitoba, Winnipeg, Manitoba, Canada (P.F.)
| | - Nigel A Calcutt
- Department of Pathology, University of California San Diego, San Diego, California (C.G.J., K.E.F., M.M.H., A.J.M., L.S.G., N.A.C.); Winsantor Inc. (K.E.F). Center for Molecular Design and Preformulations and Krembil Research Institute, University Health Network and Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada (L.P.K.); and Department of Pharmacology and Therapeutics and Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Center, University of Manitoba, Winnipeg, Manitoba, Canada (P.F.)
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Muscarinic Toxin 7 Signals Via Ca 2+/Calmodulin-Dependent Protein Kinase Kinase β to Augment Mitochondrial Function and Prevent Neurodegeneration. Mol Neurobiol 2020; 57:2521-2538. [PMID: 32198698 PMCID: PMC7253379 DOI: 10.1007/s12035-020-01900-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 03/09/2020] [Indexed: 12/29/2022]
Abstract
Mitochondrial dysfunction is implicated in a variety of neurodegenerative diseases of the nervous system. Peroxisome proliferator–activated receptor-γ coactivator-1α (PGC-1α) is a regulator of mitochondrial function in multiple cell types. In sensory neurons, AMP-activated protein kinase (AMPK) augments PGC-1α activity and this pathway is depressed in diabetes leading to mitochondrial dysfunction and neurodegeneration. Antimuscarinic drugs targeting the muscarinic acetylcholine type 1 receptor (M1R) prevent/reverse neurodegeneration by inducing nerve regeneration in rodent models of diabetes and chemotherapy-induced peripheral neuropathy (CIPN). Ca2+/calmodulin-dependent protein kinase kinase β (CaMKKβ) is an upstream regulator of AMPK activity. We hypothesized that antimuscarinic drugs modulate CaMKKβ to enhance activity of AMPK, and PGC-1α, increase mitochondrial function and thus protect from neurodegeneration. We used the specific M1R antagonist muscarinic toxin 7 (MT7) to manipulate muscarinic signaling in the dorsal root ganglia (DRG) neurons of normal rats or rats with streptozotocin-induced diabetes. DRG neurons treated with MT7 (100 nM) or a selective muscarinic antagonist, pirenzepine (1 μM), for 24 h showed increased neurite outgrowth that was blocked by the CaMKK inhibitor STO-609 (1 μM) or short hairpin RNA to CaMKKβ. MT7 enhanced AMPK phosphorylation which was blocked by STO-609 (1 μM). PGC-1α reporter activity was augmented up to 2-fold (p < 0.05) by MT7 and blocked by STO-609. Mitochondrial maximal respiration and spare respiratory capacity were elevated after 3 h of exposure to MT7 (p < 0.05). Diabetes and CIPN induced a significant (p < 0.05) decrease in corneal nerve density which was corrected by topical delivery of MT7. We reveal a novel M1R-modulated, CaMKKβ-dependent pathway in neurons that represents a therapeutic target to enhance nerve repair in two of the most common forms of peripheral neuropathy.
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27
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Andreasen LJ, Kirk RK, Fledelius C, Yorek MA, Lykkesfeldt J, Akerstrom T. Insulin Treatment Attenuates Small Nerve Fiber Damage in Rat Model of Type 2 Diabetes. J Diabetes Res 2020; 2020:9626398. [PMID: 32832565 PMCID: PMC7424504 DOI: 10.1155/2020/9626398] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 07/06/2020] [Indexed: 12/22/2022] Open
Abstract
INTRODUCTION Current clinical guidelines for management of diabetic peripheral neuropathy (DPN) emphasize good glycemic control. However, this has limited effect on prevention of DPN in type 2 diabetic (T2D) patients. This study investigates the effect of insulin treatment on development of DPN in a rat model of T2D to assess the underlying causes leading to DPN. METHODS Twelve-week-old male Sprague-Dawley rats were allocated to a normal chow diet or a 45% kcal high-fat diet. After eight weeks, the high-fat fed animals received a mild dose of streptozotocin to induce hyperglycemia. Four weeks after diabetes induction, the diabetic animals were allocated into three treatment groups receiving either no insulin or insulin-releasing implants in a high or low dose. During the 12-week treatment period, blood glucose and body weight were monitored weekly, whereas Hargreaves' test was performed four, eight, and 12 weeks after treatment initiation. At study termination, several blood parameters, body composition, and neuropathy endpoints were assessed. RESULTS Insulin treatment lowered blood glucose in a dose-dependent manner. In addition, both doses of insulin lowered lipids and increased body fat percentage. High-dose insulin treatment attenuated small nerve fiber damage assessed by Hargreaves' test and intraepidermal nerve fiber density compared to untreated diabetes and low-dose insulin; however, neuropathy was not completely prevented by tight glycemic control. Linear regression analysis revealed that glycemic status, circulating lipids, and sciatic nerve sorbitol level were all negatively associated with the small nerve fiber damage observed. CONCLUSION In summary, our data suggest that high-dose insulin treatment attenuates small nerve fiber damage. Furthermore, data also indicate that both poor glycemic control and dyslipidemia are associated with disease progression. Consequently, this rat model of T2D seems to fit well with progression of DPN in humans and could be a relevant preclinical model to use in relation to research investigating treatment opportunities for DPN.
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Affiliation(s)
- Laura J. Andreasen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 1870 Frederiksberg, Denmark
- Global Drug Discovery, Novo Nordisk A/S, 2760 Måløv, Denmark
| | - Rikke K. Kirk
- Global Drug Discovery, Novo Nordisk A/S, 2760 Måløv, Denmark
| | | | - Mark A. Yorek
- Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA 52246, USA
| | - Jens Lykkesfeldt
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 1870 Frederiksberg, Denmark
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28
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Jolivalt CG, Marquez A, Quach D, Navarro Diaz MC, Anaya C, Kifle B, Muttalib N, Sanchez G, Guernsey L, Hefferan M, Smith DR, Fernyhough P, Johe K, Calcutt NA. Amelioration of Both Central and Peripheral Neuropathy in Mouse Models of Type 1 and Type 2 Diabetes by the Neurogenic Molecule NSI-189. Diabetes 2019; 68:2143-2154. [PMID: 31492662 PMCID: PMC6804627 DOI: 10.2337/db19-0271] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 08/26/2019] [Indexed: 02/06/2023]
Abstract
While peripheral neuropathy is the most common complication of long-term diabetes, cognitive deficits associated with encephalopathy and myelopathy also occur. Diabetes is a risk factor for Alzheimer disease (AD) and increases the risk of progression from mild cognitive impairment to AD. The only current recommendation for preventing or slowing the progression of peripheral neuropathy is to maintain close glycemic control, while there is no recommendation for central nervous system disorders. NSI-189 is a new chemical entity that when orally administered promotes neurogenesis in the adult hippocampus, increases hippocampal volume, enhances synaptic plasticity, and reduces cognitive dysfunction. To establish the potential for impact on peripheral neuropathy, we first showed that NSI-189 enhances neurite outgrowth and mitochondrial functions in cultured adult rat primary sensory neurons. Oral delivery of NSI-189 to murine models of type 1 (female) and type 2 (male) diabetes prevented multiple functional and structural indices of small and large fiber peripheral neuropathy, increased hippocampal neurogenesis, synaptic markers and volume, and protected long-term memory. NSI-189 also halted progression of established peripheral and central neuropathy. NSI-189, which is currently in clinical trials for treatment of major depressive disorder, offers the opportunity for the development of a single therapeutic agent against multiple indices of central and peripheral neuropathy.
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Affiliation(s)
- Corinne G Jolivalt
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Alexandra Marquez
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | | | | | - Carlos Anaya
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Betelhem Kifle
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Nabeel Muttalib
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Gabriela Sanchez
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Lucy Guernsey
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | | | - Darrel R Smith
- St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, Manitoba, Canada
| | - Paul Fernyhough
- St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, Manitoba, Canada
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
| | | | - Nigel A Calcutt
- Department of Pathology, University of California, San Diego, La Jolla, CA
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29
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McKay TB, Priyadarsini S, Karamichos D. Mechanisms of Collagen Crosslinking in Diabetes and Keratoconus. Cells 2019; 8:cells8101239. [PMID: 31614631 PMCID: PMC6830090 DOI: 10.3390/cells8101239] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 10/09/2019] [Accepted: 10/10/2019] [Indexed: 12/14/2022] Open
Abstract
Collagen crosslinking provides the mechanical strength required for physiological maintenance of the extracellular matrix in most tissues in the human body, including the cornea. Aging and diabetes mellitus (DM) are processes that are both associated with increased collagen crosslinking that leads to increased corneal rigidity. By contrast, keratoconus (KC) is a corneal thinning disease associated with decreased mechanical stiffness leading to ectasia of the central cornea. Studies have suggested that crosslinking mediated by reactive advanced glycation end products during DM may protect the cornea from KC development. Parallel to this hypothesis, riboflavin-mediated photoreactive corneal crosslinking has been proposed as a therapeutic option to halt the progression of corneal thinning by inducing intra- and intermolecular crosslink formation within the collagen fibrils of the stroma, leading to stabilization of the disease. Here, we review the pathobiology of DM and KC in the context of corneal structure, the epidemiology behind the inverse correlation of DM and KC development, and the chemical mechanisms of lysyl oxidase-mediated crosslinking, advanced glycation end product-mediated crosslinking, and photoreactive riboflavin-mediated corneal crosslinking. The goal of this review is to define the biological and chemical pathways important in physiological and pathological processes related to collagen crosslinking in DM and KC.
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Affiliation(s)
- Tina B McKay
- Schepens Eye Research Institute/Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA.
| | - Shrestha Priyadarsini
- Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA.
| | - Dimitrios Karamichos
- Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA.
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30
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McKay TB, Seyed-Razavi Y, Ghezzi CE, Dieckmann G, Nieland TJF, Cairns DM, Pollard RE, Hamrah P, Kaplan DL. Corneal pain and experimental model development. Prog Retin Eye Res 2019; 71:88-113. [PMID: 30453079 PMCID: PMC6690397 DOI: 10.1016/j.preteyeres.2018.11.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Revised: 11/03/2018] [Accepted: 11/13/2018] [Indexed: 12/13/2022]
Abstract
The cornea is a valuable tissue for studying peripheral sensory nerve structure and regeneration due to its avascularity, transparency, and dense innervation. Somatosensory innervation of the cornea serves to identify changes in environmental stimuli at the ocular surface, thereby promoting barrier function to protect the eye against injury or infection. Due to regulatory demands to screen ocular safety of potential chemical exposure, a need remains to develop functional human tissue models to predict ocular damage and pain using in vitro-based systems to increase throughput and minimize animal use. In this review, we summarize the anatomical and functional roles of corneal innervation in propagation of sensory input, corneal neuropathies associated with pain, and the status of current in vivo and in vitro models. Emphasis is placed on tissue engineering approaches to study the human corneal pain response in vitro with integration of proper cell types, controlled microenvironment, and high-throughput readouts to predict pain induction. Further developments in this field will aid in defining molecular signatures to distinguish acute and chronic pain triggers based on the immune response and epithelial, stromal, and neuronal interactions that occur at the ocular surface that lead to functional outcomes in the brain depending on severity and persistence of the stimulus.
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Affiliation(s)
- Tina B McKay
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA
| | - Yashar Seyed-Razavi
- Center for Translational Ocular Immunology and Cornea Service, Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, MA, USA
| | - Chiara E Ghezzi
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA
| | - Gabriela Dieckmann
- Center for Translational Ocular Immunology and Cornea Service, Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, MA, USA
| | - Thomas J F Nieland
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA
| | - Dana M Cairns
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA
| | - Rachel E Pollard
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA
| | - Pedram Hamrah
- Center for Translational Ocular Immunology and Cornea Service, Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, MA, USA
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA.
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Stacpoole PW, Martyniuk CJ, James MO, Calcutt NA. Dichloroacetate-induced peripheral neuropathy. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2019; 145:211-238. [PMID: 31208525 DOI: 10.1016/bs.irn.2019.05.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Dichloroacetate (DCA) has been the focus of research by both environmental toxicologists and biomedical scientists for over 50 years. As a product of water chlorination and a metabolite of certain industrial chemicals, DCA is ubiquitous in our biosphere at low μg/kg body weight daily exposure levels without obvious adverse effects in humans. As an investigational drug for numerous congenital and acquired diseases, DCA is administered orally or parenterally, usually at doses of 10-50mg/kg per day. As a therapeutic, its principal mechanism of action is to inhibit pyruvate dehydrogenase kinase (PDK). In turn, PDK inhibits the key mitochondrial energy homeostat, pyruvate dehydrogenase complex (PDC), by reversible phosphorylation. By blocking PDK, DCA activates PDC and, consequently, the mitochondrial respiratory chain and ATP synthesis. A reversible sensory/motor peripheral neuropathy is the clinically limiting adverse effect of chronic DCA exposure and experimental data implicate the Schwann cell as a toxicological target. It has been postulated that stimulation of PDC and respiratory chain activity by DCA in normally glycolytic Schwann cells causes uncompensated oxidative stress from increased reactive oxygen species production. Additionally, the metabolism of DCA interferes with the catabolism of the amino acids phenylalanine and tyrosine and with heme synthesis, resulting in accumulation of reactive molecules capable of forming adducts with DNA and proteins and also resulting in oxidative stress. Preliminary evidence in rodent models of peripheral neuropathy suggest that DCA-induced neurotoxicity may be mitigated by naturally occurring antioxidants and by a specific class of muscarinic receptor antagonists. These findings generate a number of testable hypotheses regarding the etiology and treatment of DCA peripheral neuropathy.
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Affiliation(s)
- Peter W Stacpoole
- Department of Medicine, College of Medicine, University of Florida, Gainesville, FL, United States; Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, United States.
| | - Christopher J Martyniuk
- Department of Physiological Sciences, Center for Environmental and Human Toxicology, College of Veterinary Medicine, University of Florida, Gainesville, FL, United States
| | - Margaret O James
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, FL, United States
| | - Nigel A Calcutt
- Department of Pathology, University of California San Diego, La Jolla, CA, United States
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Aghanoori MR, Smith DR, Shariati-Ievari S, Ajisebutu A, Nguyen A, Desmond F, Jesus CHA, Zhou X, Calcutt NA, Aliani M, Fernyhough P. Insulin-like growth factor-1 activates AMPK to augment mitochondrial function and correct neuronal metabolism in sensory neurons in type 1 diabetes. Mol Metab 2019; 20:149-165. [PMID: 30545741 PMCID: PMC6358538 DOI: 10.1016/j.molmet.2018.11.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 11/20/2018] [Accepted: 11/23/2018] [Indexed: 12/13/2022] Open
Abstract
OBJECTIVE Diabetic sensorimotor polyneuropathy (DSPN) affects approximately half of diabetic patients leading to significant morbidity. There is impaired neurotrophic growth factor signaling, AMP-activated protein kinase (AMPK) activity and mitochondrial function in dorsal root ganglia (DRG) of animal models of type 1 and type 2 diabetes. We hypothesized that sub-optimal insulin-like growth factor 1 (IGF-1) signaling in diabetes drives loss of AMPK activity and mitochondrial function, both contributing to development of DSPN. METHODS Age-matched control Sprague-Dawley rats and streptozotocin (STZ)-induced type 1 diabetic rats with/without IGF-1 therapy were used for in vivo studies. For in vitro studies, DRG neurons from control and STZ-diabetic rats were cultured and treated with/without IGF-1 in the presence or absence of inhibitors or siRNAs. RESULTS Dysregulation of mRNAs for IGF-1, AMPKα2, ATP5a1 (subunit of ATPase), and PGC-1β occurred in DRG of diabetic vs. control rats. IGF-1 up-regulated mRNA levels of these genes in cultured DRGs from control or diabetic rats. IGF-1 treatment of DRG cultures significantly (P < 0.05) increased phosphorylation of Akt, P70S6K, AMPK and acetyl-CoA carboxylase (ACC). Mitochondrial gene expression and oxygen consumption rate (spare respiratory capacity), ATP production, mtDNA/nDNA ratio and neurite outgrowth were augmented (P < 0.05). AMPK inhibitor, Compound C, or AMPKα1-specific siRNA suppressed IGF-1 elevation of mitochondrial function, mtDNA and neurite outgrowth. Diabetic rats treated with IGF-1 exhibited reversal of thermal hypoalgesia and, in a separate study, reversed the deficit in corneal nerve profiles. In diabetic rats, IGF-1 elevated the levels of AMPK and P70S6K phosphorylation, raised Complex IV-MTCO1 and Complex V-ATP5a protein expression, and restored the enzyme activities of Complex IV and I in the DRG. IGF-1 prevented TCA metabolite build-up in nerve. CONCLUSIONS In DRG neuron cultures IGF-1 signals via AMPK to elevate mitochondrial function and drive axonal outgrowth. We propose that this signaling axis mediates IGF-1-dependent protection from distal dying-back of fibers in diabetic neuropathy.
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Affiliation(s)
- Mohamad-Reza Aghanoori
- Division of Neurodegenerative Disorders, St Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada; Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada
| | - Darrell R Smith
- Division of Neurodegenerative Disorders, St Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada
| | - Shiva Shariati-Ievari
- Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, Canada
| | - Andrew Ajisebutu
- Division of Neurodegenerative Disorders, St Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada
| | - Annee Nguyen
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Fiona Desmond
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Carlos H A Jesus
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Xiajun Zhou
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Nigel A Calcutt
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Michel Aliani
- Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, MB, Canada; Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, Canada; Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Canada
| | - Paul Fernyhough
- Division of Neurodegenerative Disorders, St Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada; Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada.
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Abstract
Diabetes mellitus (DM) has been emerging as one of the most serious health problems worldwide. Ocular complications of DM are currently one of the major causes of blindness in developed countries, among which diabetic retinopathy is relatively well studied and understood. However, although ocular surface complications of DM are common, diabetic complications of anterior segment of the eye, such as, cornea, conjunctiva, and lacrimal glands, are often overlooked. DM is associated with progressive damage to corneal nerves and epithelial cells, which increases the risk of anterior segment disorders including dry eye disease, corneal erosion, persistent epithelial defects, and even sight-threatening corneal ulcer. In this review, the authors will discuss the association of DM with disorders of anterior segment of the eye. Studies indicating the value of corneal nerve assessment as a sensitive, noninvasive, and repeatable biomarker for diabetic neuropathy will also be introduced. In addition, treatment modalities of anterior segment disorders associated with DM is discussed. The studies introduced in this review suggest that early and periodic screening of the anterior segment of the eye, as well as the retina, is important for the optimal treatment of DM.
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Affiliation(s)
- Sang Beom Han
- Department of Ophthalmology, School of Medicine, Kangwon National University, Kangwon National University Hospital, Chuncheon, Korea,
| | - Hee Kyung Yang
- Department of Ophthalmology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
| | - Joon Young Hyon
- Department of Ophthalmology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
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Mahelková G, Burdová MC, Malá Š, Hoskovcová L, Dotrelová D, Štechová K. Higher Total Insulin Dose Has Positive Effect on Corneal Nerve Fibers in DM1 Patients. ACTA ACUST UNITED AC 2018; 59:3800-3807. [DOI: 10.1167/iovs.18-24265] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Gabriela Mahelková
- Department of Ophthalmology, Charles University, 2nd Faculty of Medicine, Motol University Hospital, Prague, Czech Republic
- Department of Physiology, Charles University, 2nd Faculty of Medicine, Prague, Czech Republic
| | - Marie Ceská Burdová
- Department of Ophthalmology, Charles University, 2nd Faculty of Medicine, Motol University Hospital, Prague, Czech Republic
- Department of Physiology, Charles University, 2nd Faculty of Medicine, Prague, Czech Republic
| | - Šárka Malá
- Department of Internal Medicine, Charles University, 2nd Faculty of Medicine, Motol University Hospital, Prague, Czech Republic
| | - Lucie Hoskovcová
- Department of Internal Medicine, Charles University, 2nd Faculty of Medicine, Motol University Hospital, Prague, Czech Republic
| | - Dagmar Dotrelová
- Department of Ophthalmology, Charles University, 2nd Faculty of Medicine, Motol University Hospital, Prague, Czech Republic
| | - Katerina Štechová
- Department of Internal Medicine, Charles University, 2nd Faculty of Medicine, Motol University Hospital, Prague, Czech Republic
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Abstract
PURPOSE To report the clinical course of 6 patients with refractory neurotrophic corneal ulcers that were treated with topical insulin drops. METHODS Retrospective chart review of patients who had neurotrophic corneal ulcers or epithelial defects refractory to standard medical and surgical treatment. Insulin drops, prepared by mixing regular insulin in artificial tears with a polyethylene glycol and propylene glycol base at a concentration of 1 unit per milliliter, were prescribed 2 to 3 times daily. RESULTS Six patients, aged 2 to 73 years, developed neurotrophic corneal ulcers refractory to a range of medical and surgical treatments, including bandage contact lens, amniotic membrane grafting, and permanent tarsorrhaphy. Each patient was administered topical insulin drops with complete corneal reepithelialization within 7 to 25 days. CONCLUSIONS Topical insulin may be a simple and effective treatment for refractory neurotrophic corneal ulcers. Further study is required to determine the clinical efficacy and side effect profile of insulin drops.
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36
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The impact of diabetes on corneal nerve morphology and ocular surface integrity. Ocul Surf 2018; 16:45-57. [DOI: 10.1016/j.jtos.2017.10.006] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 10/03/2017] [Accepted: 10/26/2017] [Indexed: 12/11/2022]
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Aghanoori MR, Smith DR, Roy Chowdhury S, Sabbir MG, Calcutt NA, Fernyhough P. Insulin prevents aberrant mitochondrial phenotype in sensory neurons of type 1 diabetic rats. Exp Neurol 2017; 297:148-157. [PMID: 28803751 DOI: 10.1016/j.expneurol.2017.08.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 08/02/2017] [Accepted: 08/10/2017] [Indexed: 01/08/2023]
Abstract
Diabetic neuropathy affects approximately 50% of diabetic patients. Down-regulation of mitochondrial gene expression and function has been reported in both human tissues and in dorsal root ganglia (DRG) from animal models of type 1 and type 2 diabetes. We hypothesized that loss of direct insulin signaling in diabetes contributes to loss of mitochondrial function in DRG neurons and to development of neuropathy. Sensory neurons obtained from age-matched adult control or streptozotocin (STZ)-induced type 1 diabetic rats were cultured with or without insulin before determining mitochondrial respiration and expression of mitochondrial respiratory chain and insulin signaling-linked proteins. For in vivo studies age-matched control rats and diabetic rats with or without trace insulin supplementation were maintained for 5months before DRG were analyzed for respiratory chain gene expression and cytochrome c oxidase activity. Insulin (10nM) significantly (P<0.05) increased phosphorylation of Akt and P70S6K by 4-fold and neurite outgrowth by 2-fold in DRG cultures derived from adult control rats. Insulin also augmented the levels of selective mitochondrial respiratory chain proteins and mitochondrial bioenergetics parameters in DRG cultures from control and diabetic rats, with spare respiratory capacity increased by up to 3-fold (P<0.05). Insulin-treated diabetic animals exhibited improved thermal sensitivity in the hind paw and had increased dermal nerve density compared to untreated diabetic rats, despite no effect on blood glucose levels. In DRG of diabetic rats there was suppressed expression of mitochondrial respiratory chain proteins and cytochrome c oxidase activity that was corrected by insulin therapy. Insulin elevates mitochondrial respiratory chain protein expression and function in sensory neurons and this is associated with enhanced neurite outgrowth and protection against indices of neuropathy.
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Affiliation(s)
- Mohamad-Reza Aghanoori
- Division of Neurodegenerative Disorders, St Boniface Hospital Research Centre, Winnipeg, MB, Canada; Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada
| | - Darrell R Smith
- Division of Neurodegenerative Disorders, St Boniface Hospital Research Centre, Winnipeg, MB, Canada
| | - Subir Roy Chowdhury
- Division of Neurodegenerative Disorders, St Boniface Hospital Research Centre, Winnipeg, MB, Canada
| | - Mohammad Golam Sabbir
- Division of Neurodegenerative Disorders, St Boniface Hospital Research Centre, Winnipeg, MB, Canada
| | - Nigel A Calcutt
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Paul Fernyhough
- Division of Neurodegenerative Disorders, St Boniface Hospital Research Centre, Winnipeg, MB, Canada; Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada.
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38
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Sullivan DA, Rocha EM, Aragona P, Clayton JA, Ding J, Golebiowski B, Hampel U, McDermott AM, Schaumberg DA, Srinivasan S, Versura P, Willcox MDP. TFOS DEWS II Sex, Gender, and Hormones Report. Ocul Surf 2017; 15:284-333. [PMID: 28736336 DOI: 10.1016/j.jtos.2017.04.001] [Citation(s) in RCA: 236] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 04/16/2017] [Indexed: 12/21/2022]
Abstract
One of the most compelling features of dry eye disease (DED) is that it occurs more frequently in women than men. In fact, the female sex is a significant risk factor for the development of DED. This sex-related difference in DED prevalence is attributed in large part to the effects of sex steroids (e.g. androgens, estrogens), hypothalamic-pituitary hormones, glucocorticoids, insulin, insulin-like growth factor 1 and thyroid hormones, as well as to the sex chromosome complement, sex-specific autosomal factors and epigenetics (e.g. microRNAs). In addition to sex, gender also appears to be a risk factor for DED. "Gender" and "sex" are words that are often used interchangeably, but they have distinct meanings. "Gender" refers to a person's self-representation as a man or woman, whereas "sex" distinguishes males and females based on their biological characteristics. Both gender and sex affect DED risk, presentation of the disease, immune responses, pain, care-seeking behaviors, service utilization, and myriad other facets of eye health. Overall, sex, gender and hormones play a major role in the regulation of ocular surface and adnexal tissues, and in the difference in DED prevalence between women and men. The purpose of this Subcommittee report is to review and critique the nature of this role, as well as to recommend areas for future research to advance our understanding of the interrelationships between sex, gender, hormones and DED.
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Affiliation(s)
- David A Sullivan
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA.
| | - Eduardo M Rocha
- Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Pasquale Aragona
- Department of Biomedical Sciences, Ocular Surface Diseases Unit, University of Messina, Messina, Sicily, Italy
| | - Janine A Clayton
- National Institutes of Health Office of Research on Women's Health, Bethesda, MD, USA
| | - Juan Ding
- Schepens Eye Research Institute, Massachusetts Eye & Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Blanka Golebiowski
- School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
| | - Ulrike Hampel
- Department of Ophthalmology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Alison M McDermott
- The Ocular Surface Institute, College of Optometry, University of Houston, Houston, TX, USA
| | - Debra A Schaumberg
- Harvard School of Public Health, Boston, MA, USA; University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Sruthi Srinivasan
- Centre for Contact Lens Research, School of Optometry, University of Waterloo, Ontario, Canada
| | - Piera Versura
- Department of Specialized, Experimental, and Diagnostic Medicine, University of Bologna, Bologna, Italy
| | - Mark D P Willcox
- School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
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Marshall AG, Lee-Kubli C, Azmi S, Zhang M, Ferdousi M, Mixcoatl-Zecuatl T, Petropoulos IN, Ponirakis G, Fineman MS, Fadavi H, Frizzi K, Tavakoli M, Jeziorska M, Jolivalt CG, Boulton AJM, Efron N, Calcutt NA, Malik RA. Spinal Disinhibition in Experimental and Clinical Painful Diabetic Neuropathy. Diabetes 2017; 66:1380-1390. [PMID: 28202580 PMCID: PMC5399611 DOI: 10.2337/db16-1181] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 02/08/2017] [Indexed: 12/18/2022]
Abstract
Impaired rate-dependent depression (RDD) of the Hoffman reflex is associated with reduced dorsal spinal cord potassium chloride cotransporter expression and impaired spinal γ-aminobutyric acid type A receptor function, indicative of spinal inhibitory dysfunction. We have investigated the pathogenesis of impaired RDD in diabetic rodents exhibiting features of painful neuropathy and the translational potential of this marker of spinal inhibitory dysfunction in human painful diabetic neuropathy. Impaired RDD and allodynia were present in type 1 and type 2 diabetic rats but not in rats with type 1 diabetes receiving insulin supplementation that did not restore normoglycemia. Impaired RDD in diabetic rats was rapidly normalized by spinal delivery of duloxetine acting via 5-hydroxytryptamine type 2A receptors and temporally coincident with the alleviation of allodynia. Deficits in RDD and corneal nerve density were demonstrated in patients with painful diabetic neuropathy compared with healthy control subjects and patients with painless diabetic neuropathy. Spinal inhibitory dysfunction and peripheral small fiber pathology may contribute to the clinical phenotype in painful diabetic neuropathy. Deficits in RDD may help identify patients with spinally mediated painful diabetic neuropathy who may respond optimally to therapies such as duloxetine.
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Affiliation(s)
- Andrew G Marshall
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
- Department of Clinical Neurophysiology, Manchester Royal Infirmary, Central Manchester University Hospitals National Health Service Foundation Trust, Manchester Academic Health Science Centre, Manchester, U.K
| | - Corinne Lee-Kubli
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Shazli Azmi
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
| | - Michael Zhang
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, U.K
| | - Maryam Ferdousi
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
| | | | - Ioannis N Petropoulos
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
- Department of Medicine, Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Georgios Ponirakis
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
- Department of Medicine, Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Mark S Fineman
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Hassan Fadavi
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
| | - Katie Frizzi
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Mitra Tavakoli
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
- Faculty of Medicine, University of Exeter Medical School, Exeter, U.K
| | - Maria Jeziorska
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
| | - Corinne G Jolivalt
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Andrew J M Boulton
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
| | - Nathan Efron
- School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Australia
| | - Nigel A Calcutt
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Rayaz A Malik
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K.
- Department of Medicine, Weill Cornell Medicine-Qatar, Doha, Qatar
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de la Hoz CL, Cheng C, Fernyhough P, Zochodne DW. A model of chronic diabetic polyneuropathy: benefits from intranasal insulin are modified by sex and RAGE deletion. Am J Physiol Endocrinol Metab 2017; 312:E407-E419. [PMID: 28223295 PMCID: PMC5451527 DOI: 10.1152/ajpendo.00444.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 02/06/2017] [Accepted: 02/18/2017] [Indexed: 01/11/2023]
Abstract
Human diabetic polyneuropathy (DPN) is a progressive complication of chronic diabetes mellitus. Preliminary evidence has suggested that intranasal insulin, in doses insufficient to alter hyperglycemia, suppresses the development of DPN. In this work we confirm this finding, but demonstrate that its impact is modified by sex and deletion of RAGE, the receptor for advanced glycosylation end products. We serially evaluated experimental DPN in male and female wild-type mice and male RAGE null (RN) mice, each with nondiabetic controls, during 16 wk of diabetes, the final 8 wk including groups given intranasal insulin. Age-matched nondiabetic female mice had higher motor and sensory conduction velocities than their male counterparts and had lesser conduction slowing from chronic diabetes. Intranasal insulin improved slowing in both sexes. In male RN mice, there was less conduction slowing with chronic diabetes, and intranasal insulin provided limited benefits. Rotarod testing and hindpaw grip power offered less consistent impacts. Mechanical sensitivity and thermal sensitivity were respectively but disparately changed and improved with insulin in wild-type female and male mice but not RN male mice. These studies confirm that intranasal insulin improves indexes of experimental DPN but indicates that females with DPN may differ in their underlying phenotype. RN mice had partial but incomplete protection from underlying DPN and lesser impacts from insulin. We also identify an important role for sex in the development of DPN and report evidence that insulin and AGE-RAGE pathways in its pathogenesis may overlap.
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Affiliation(s)
- Cristiane L de la Hoz
- Department of Clinical Neurosciences, the Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; and
| | - Chu Cheng
- Department of Clinical Neurosciences, the Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; and
| | - Paul Fernyhough
- Division of Neurodegenerative Disorders, St Boniface Hospital Research Centre and Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Douglas W Zochodne
- Division of Neurology, Department of Medicine, Neuroscience and Mental Health Institute, Alberta Diabetes Institute, University of Alberta, Alberta, Canada;
- Department of Clinical Neurosciences, the Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; and
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41
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Diabetic complications in the cornea. Vision Res 2017; 139:138-152. [PMID: 28404521 DOI: 10.1016/j.visres.2017.03.002] [Citation(s) in RCA: 148] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 03/31/2017] [Accepted: 03/31/2017] [Indexed: 12/15/2022]
Abstract
Diabetic corneal alterations, such as delayed epithelial wound healing, edema, recurrent erosions, neuropathy/loss of sensitivity, and tear film changes are frequent but underdiagnosed complications of both type 1 (insulin-dependent) and type 2 (non-insulin-dependent) diabetes mellitus. The disease affects corneal epithelium, corneal nerves, tear film, and to a lesser extent, endothelium, and also conjunctiva. These abnormalities may appear or become exacerbated following trauma, as well as various surgeries including retinal, cataract or refractive. The focus of the review is on mechanisms of diabetic corneal abnormalities, available animal, tissue and organ culture models, and emerging treatments. Changes of basement membrane structure and wound healing rates, the role of various proteinases, advanced glycation end products (AGEs), abnormal growth and motility factors (including opioid, epidermal, and hepatocyte growth factors) are analyzed. Experimental therapeutics under development, including topical naltrexone, insulin, inhibitors of aldose reductase, and AGEs, as well as emerging gene and cell therapies are discussed in detail.
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Abstract
Corneal immunoimaging and neuroimaging approaches facilitate in vivo analyses of the cornea, including high-resolution imaging of corneal immune cells and nerves. This approach facilitates the analyses of underlying immune and nerve alterations not detected by clinical slit-lamp examination alone. In this review, we describe recent work performed in our translational ocular immunology center with a focus on "bench-to-bedside" and "bedside-to-bench" research. The ability to visualize dendritiform immune cells (DCs) in patients with laser in vivo confocal microscopy (IVCM), recently discovered in the central murine cornea, has allowed us to demonstrate their utility as a potential surrogate biomarker for inflammatory ocular surface diseases. This biomarker for inflammation allows the measurement of therapeutic efficacy of anti-inflammatory drugs and its utility as an endpoint in clinical trials with high interobserver agreement. IVCM image analyses from our studies has demonstrated a significant increase in DC density and size in ocular disease, a positive correlation between DC density and clinical signs and symptoms of disease and pro-inflammatory tear cytokines, and a strong negative correlation between DC density and subbasal nerve density. In conjunction with preclinical research investigating the inflammatory state in a partial or fully denervated cornea, our results indicated that corneal nerves are directly involved in the regulation of homeostasis and immune privilege in the cornea.
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A systematic review on the impact of diabetes mellitus on the ocular surface. Nutr Diabetes 2017; 7:e251. [PMID: 28319106 PMCID: PMC5380897 DOI: 10.1038/nutd.2017.4] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 11/10/2016] [Accepted: 11/14/2016] [Indexed: 12/27/2022] Open
Abstract
Diabetes mellitus is associated with extensive morbidity and mortality in any human community. It is well understood that the burden of diabetes is attributed to chronic progressive damage in major end-organs, but it is underappreciated that the most superficial and transparent organ affected by diabetes is the cornea. Different corneal components (epithelium, nerves, immune cells and endothelium) underpin specific systemic complications of diabetes. Just as diabetic retinopathy is a marker of more generalized microvascular disease, corneal nerve changes can predict peripheral and autonomic neuropathy, providing a window of opportunity for early treatment. In addition, alterations of immune cells in corneas suggest an inflammatory component in diabetic complications. Furthermore, impaired corneal epithelial wound healing may also imply more widespread disease. The non-invasiveness and improvement in imaging technology facilitates the emergence of new screening tools. Systemic control of diabetes can improve ocular surface health, possibly aided by anti-inflammatory and vasoprotective agents.
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Calcutt NA, Smith DR, Frizzi K, Sabbir MG, Chowdhury SKR, Mixcoatl-Zecuatl T, Saleh A, Muttalib N, Van der Ploeg R, Ochoa J, Gopaul A, Tessler L, Wess J, Jolivalt CG, Fernyhough P. Selective antagonism of muscarinic receptors is neuroprotective in peripheral neuropathy. J Clin Invest 2017; 127:608-622. [PMID: 28094765 DOI: 10.1172/jci88321] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 11/22/2016] [Indexed: 01/29/2023] Open
Abstract
Sensory neurons have the capacity to produce, release, and respond to acetylcholine (ACh), but the functional role of cholinergic systems in adult mammalian peripheral sensory nerves has not been established. Here, we have reported that neurite outgrowth from adult sensory neurons that were maintained under subsaturating neurotrophic factor conditions operates under cholinergic constraint that is mediated by muscarinic receptor-dependent regulation of mitochondrial function via AMPK. Sensory neurons from mice lacking the muscarinic ACh type 1 receptor (M1R) exhibited enhanced neurite outgrowth, confirming the role of M1R in tonic suppression of axonal plasticity. M1R-deficient mice made diabetic with streptozotocin were protected from physiological and structural indices of sensory neuropathy. Pharmacological blockade of M1R using specific or selective antagonists, pirenzepine, VU0255035, or muscarinic toxin 7 (MT7) activated AMPK and overcame diabetes-induced mitochondrial dysfunction in vitro and in vivo. These antimuscarinic drugs prevented or reversed indices of peripheral neuropathy, such as depletion of sensory nerve terminals, thermal hypoalgesia, and nerve conduction slowing in diverse rodent models of diabetes. Pirenzepine and MT7 also prevented peripheral neuropathy induced by the chemotherapeutic agents dichloroacetate and paclitaxel or HIV envelope protein gp120. As a variety of antimuscarinic drugs are approved for clinical use against other conditions, prompt translation of this therapeutic approach to clinical trials is feasible.
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45
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Grote CW, Wright DE. A Role for Insulin in Diabetic Neuropathy. Front Neurosci 2016; 10:581. [PMID: 28066166 PMCID: PMC5179551 DOI: 10.3389/fnins.2016.00581] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 12/06/2016] [Indexed: 12/13/2022] Open
Abstract
The peripheral nervous system is one of several organ systems that are profoundly affected in diabetes. The longstanding view is that insulin does not have a major role in modulating neuronal function in both central and peripheral nervous systems is now being challenged. In the setting of insulin deficiency or excess insulin, it is logical to propose that insulin dysregulation can contribute to neuropathic changes in sensory neurons. This is particularly important as sensory nerve damage associated with prediabetes, type 1 and type 2 diabetes is so prevalent. Here, we discuss the current experimental literature related to insulin's role as a potential neurotrophic factor in peripheral nerve function, as well as the possibility that insulin deficiency plays a role in diabetic neuropathy. In addition, we discuss how sensory neurons in the peripheral nervous system respond to insulin similar to other insulin-sensitive tissues. Moreover, studies now suggest that sensory neurons can also become insulin resistant like other tissues. Collectively, emerging studies are revealing that insulin signaling pathways are active contributors to sensory nerve modulation, and this review highlights this novel activity and should provide new insight into insulin's role in both peripheral and central nervous system diseases.
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Affiliation(s)
- Caleb W Grote
- Department of Anatomy and Cell Biology, University of Kansas Medical Center Kansas City, KS, USA
| | - Douglas E Wright
- Department of Anatomy and Cell Biology, University of Kansas Medical Center Kansas City, KS, USA
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46
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Neuronal Changes in the Diabetic Cornea: Perspectives for Neuroprotection. BIOMED RESEARCH INTERNATIONAL 2016; 2016:5140823. [PMID: 28044131 PMCID: PMC5156788 DOI: 10.1155/2016/5140823] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 10/14/2016] [Accepted: 10/23/2016] [Indexed: 01/17/2023]
Abstract
Diabetic neuropathy is associated with neurotrophic ulcerations of the skin and cornea. Decreased corneal sensitivity and impaired innervation lead to weakened epithelial wound healing predisposing patients to ocular complications such as corneal infections, stromal opacification, and surface irregularity. This review presents recent findings on impaired corneal innervation in diabetic individuals, and the findings suggest that corneal neuropathy might be an early indicator of diabetic neuropathy. Additionally, the recent findings for neuroprotective and regenerative therapy for diabetic keratopathy are presented.
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47
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Leckelt J, Guimarães P, Kott A, Ruggeri A, Stachs O, Baltrusch S. Early detection of diabetic neuropathy by investigating CNFL and IENFD in thy1-YFP mice. J Endocrinol 2016; 231:147-157. [PMID: 27601446 DOI: 10.1530/joe-16-0284] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 09/06/2016] [Indexed: 01/19/2023]
Abstract
Small fiber neuropathy is one of the most common and painful long-term complications of diabetes mellitus. Examination of the sub-basal corneal nerve plexus is a promising surrogate marker of diabetic neuropathy. To investigate the efficacy, reliability and reproducibility of in vivo corneal confocal microscopy (IVCCM), we used thy1-YFP mice, which express yellow fluorescence protein (YFP) in nerve fibers. 4 weeks after multiple low-dose injections of streptozotocin, thy1-YFP mice showed manifest diabetes. Subsequent application of insulin-releasing pellets for 8 weeks resulted in a significant reduction of blood glucose concentration and HbA1c, a significant increase in body weight and no further increase in advanced glycation end products (AGEs). IVCCM, carried out regularly over 12 weeks and analyzed both manually and automatically, revealed a significant loss of corneal nerve fiber length (CNFL) during diabetes manifestation and significant recovery after insulin therapy. Ex vivo analyses of CNFL by YFP-based microscopy confirmed the IVCCM results (with high sensitivity between manual and automated approaches) but demonstrated that the changes were restricted to the central cornea. Peripheral areas, not accessible by IVCCM in mice, remained virtually unaffected. Because parallel assessment of intraepidermal nerve fiber density revealed no changes, we conclude that IVCCM robustly captures early signs of diabetic neuropathy.
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Affiliation(s)
- Janine Leckelt
- Institute of Medical Biochemistry and Molecular BiologyUniversity of Rostock, Rostock, Germany
| | - Pedro Guimarães
- Department of Information EngineeringUniversity of Padua, Padua, Italy
| | - Annett Kott
- Institute of Medical Biochemistry and Molecular BiologyUniversity of Rostock, Rostock, Germany
| | - Alfredo Ruggeri
- Department of Information EngineeringUniversity of Padua, Padua, Italy
| | - Oliver Stachs
- Department of OphthalmologyUniversity of Rostock, Rostock, Germany
| | - Simone Baltrusch
- Institute of Medical Biochemistry and Molecular BiologyUniversity of Rostock, Rostock, Germany
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48
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Jolivalt CG, Frizzi KE, Guernsey L, Marquez A, Ochoa J, Rodriguez M, Calcutt NA. Peripheral Neuropathy in Mouse Models of Diabetes. ACTA ACUST UNITED AC 2016; 6:223-255. [PMID: 27584552 DOI: 10.1002/cpmo.11] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Peripheral neuropathy is a frequent complication of chronic diabetes that most commonly presents as a distal degenerative polyneuropathy with sensory loss. Around 20% to 30% of such patients may also experience neuropathic pain. The underlying pathogenic mechanisms are uncertain, and therapeutic options are limited. Rodent models of diabetes have been used for more than 40 years to study neuropathy and evaluate potential therapies. For much of this period, streptozotocin-diabetic rats were the model of choice. The emergence of new technologies that allow relatively cheap and routine manipulations of the mouse genome has prompted increased use of mouse models of diabetes to study neuropathy. In this article, we describe the commonly used mouse models of type 1 and type 2 diabetes, and provide protocols to phenotype the structural, functional, and behavioral indices of peripheral neuropathy, with a particular emphasis on assays pertinent to the human condition. © 2016 by John Wiley & Sons, Inc.
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Affiliation(s)
- Corinne G Jolivalt
- Department of Pathology, University of California San Diego, La Jolla, California
| | - Katie E Frizzi
- Department of Pathology, University of California San Diego, La Jolla, California
| | - Lucie Guernsey
- Department of Pathology, University of California San Diego, La Jolla, California
| | - Alex Marquez
- Department of Pathology, University of California San Diego, La Jolla, California
| | - Joseline Ochoa
- Department of Pathology, University of California San Diego, La Jolla, California
| | - Maria Rodriguez
- Department of Pathology, University of California San Diego, La Jolla, California
| | - Nigel A Calcutt
- Department of Pathology, University of California San Diego, La Jolla, California
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49
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Freeman OJ, Evans MH, Cooper GJS, Petersen RS, Gardiner NJ. Thalamic amplification of sensory input in experimental diabetes. Eur J Neurosci 2016; 44:1779-86. [PMID: 27152754 PMCID: PMC4950294 DOI: 10.1111/ejn.13267] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 04/13/2016] [Accepted: 05/04/2016] [Indexed: 12/29/2022]
Abstract
Diabetic neuropathy is a common, and often debilitating, secondary complication of diabetes mellitus. As pain, hypersensitivity and paraesthesias present in a distal-proximal distribution, symptoms are generally believed to originate from damaged afferents within the peripheral nervous system. Increasing evidence suggests altered processing within the central nervous system in diabetic neuropathy contributes towards somatosensory dysfunction, but whether the accurate coding and relay of peripherally encoded information through the central nervous system is altered in diabetes is not understood. Here, we applied the strengths of the rodent whisker-barrel system to study primary afferent-thalamic processing in diabetic neuropathy. We found that neurons in the thalamic ventral posteromedial nucleus from rats with experimental diabetic neuropathy showed increased firing to precisely graded, multidirectional whisker deflection compared to non-diabetic rats. This thalamic hyperactivity occurred without any overt primary afferent dysfunction, as recordings from the trigeminal ganglion showed these primary afferents to be unaffected by diabetes. These findings suggest that central amplification can substantially transform ascending sensory input in diabetes, even in the absence of a barrage of ectopic primary afferent activity.
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Affiliation(s)
- Oliver J Freeman
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, M13 9PT, UK
| | - Mathew H Evans
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, M13 9PT, UK
| | - Garth J S Cooper
- Centre for Advanced Discovery and Experimental Therapeutics (CADET), Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Sciences Centre, Manchester, UK.,Centre for Endocrinology and Diabetes, Institute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK.,School of Biological Sciences, University of Auckland, Auckland, New Zealand.,Medical Sciences Division, Department of Pharmacology, University of Oxford, Oxford, UK
| | - Rasmus S Petersen
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, M13 9PT, UK
| | - Natalie J Gardiner
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, M13 9PT, UK
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50
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Zochodne DW. Sensory Neurodegeneration in Diabetes: Beyond Glucotoxicity. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 127:151-80. [PMID: 27133149 DOI: 10.1016/bs.irn.2016.03.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Diabetic polyneuropathy in humans is of gradual, sometimes insidious onset, and is more likely to occur if glucose control is poor. Arguments that the disorder arises chiefly from glucose toxicity however ignore the greater complexity of a unique neurodegenerative disorder. For example, sensory neurons regularly thrive in media with levels of glucose at or exceeding those of poorly controlled diabetic persons. Also, all of the linkages between hyperglycemia and neuropathy develop in the setting of altered insulin availability or sensitivity. Insulin itself is recognized as a potent growth, or trophic factor for adult sensory neurons. Low doses of insulin, insufficient to alter blood glucose levels, reverse features of diabetic neurodegeneration in animal models. Insulin resistance, as occurs in diabetic adipose tissue, liver, and muscle, also develops in sensory neurons, offering a mechanism for neurodegeneration in the setting of normal or elevated insulin levels. Other interventions that "shore up" sensory neurons prevent features of diabetic polyneuropathy from developing despite persistent hyperglycemia. More recently evidence has emerged that a series of subtle molecular changes in sensory neurons can be linked to neurodegeneration including epigenetic changes in the control of gene expression. Understanding the new complexity of sensory neuron degeneration may give rise to therapeutic strategies that have a higher chance of success in the clinical trial arena.
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Affiliation(s)
- D W Zochodne
- Neuroscience and Mental Health Institute and Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada.
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