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Liu R, Dang JN, Lee R, Lee JJ, Kesavamoorthy N, Ameri H, Rao N, Eoh H. Mycobacterium dormancy and antibiotic tolerance within the retinal pigment epithelium of ocular tuberculosis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.18.585612. [PMID: 38562751 PMCID: PMC10983995 DOI: 10.1101/2024.03.18.585612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Tuberculosis (TB) is a leading cause of death among infectious diseases worldwide due to latent TB infection, which is the critical step for the successful pathogenic cycle. In this stage, Mycobacterium tuberculosis resides inside the host in a dormant and antibiotic-tolerant state. Latent TB infection can lead to a multisystemic diseases because M. tuberculosis invades virtually all organs, including ocular tissues. Ocular tuberculosis (OTB) occurs when the dormant bacilli within ocular tissues reactivate, originally seeded by hematogenous spread from pulmonary TB. Timely and accurate diagnosis as well as efficient chemotherapies are crucial in preventing poor visual outcomes of OTB patients. Histological evidence suggests that retinal pigment epithelium (RPE) cells play a central role in immune privilege and in the protection from the antibiotic effects, making them an anatomical niche for invading M. tuberculosis . RPE cells exhibit high tolerance to environmental redox stresses, allowing phagocytosed M. tuberculosis bacilli to maintain viability in a dormant state. However, the microbiological and metabolic mechanisms determining the interaction between the RPE intracellular environment and phagocytosed M. tuberculosis are largely unknown. Here, liquid chromatography mass spectrometry (LC-MS) metabolomics was used to illuminate the metabolic state within RPE cells reprogrammed to harbor dormant M. tuberculosis bacilli and enhance the antibiotic tolerance. The results have led to propose a novel therapeutic option to synthetically kill the dormant M. tuberculosis inside the RPE cells by modulating the phenotypic state of M. tuberculosis , thus laying the foundation for a new, innovative regimen for treating OTB. Importance Understanding the metabolic environment within the retinal pigment epithelium (RPE) cells altered by infection with M. tuberculosis and mycobacterial dormancy is crucial to identify new therapeutic methods to cure OTB. The present study showed that RPE cellular metabolism is altered to foster intracellular M. tuberculosis to enter into the dormant and drug tolerant state, thereby blunting the efficacy of anti-TB chemotherapy. RPE cells serve as an anatomical niche as the cells protect invading bacilli from antibiotic treatment. LC-MS metabolomics of RPE cells after co-treatment with H2O2 and M. tuberculosis infection showed that intracellular environment within RPE cells is enriched with greater level of oxidative stress. The antibiotic tolerance of intracellular M. tuberculosis within RPE cells can be restored by a metabolic manipulation strategy such as co-treatment of antibiotic with the most downstream glycolysis metabolite, phosphoenolpyruvate.
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Dörschmann P, Thalenhorst T, Seeba C, Tischhöfer MT, Neupane S, Roider J, Alban S, Klettner A. Comparison of Fucoidans from Saccharina latissima Regarding Age-Related Macular Degeneration Relevant Pathomechanisms in Retinal Pigment Epithelium. Int J Mol Sci 2023; 24:7939. [PMID: 37175646 PMCID: PMC10178501 DOI: 10.3390/ijms24097939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 04/16/2023] [Accepted: 04/25/2023] [Indexed: 05/15/2023] Open
Abstract
Fucoidans from brown algae are described as anti-inflammatory, antioxidative, and antiangiogenic. We tested two Saccharina latissima fucoidans (SL-FRO and SL-NOR) regarding their potential biological effects against age-related macular degeneration (AMD). Primary porcine retinal pigment epithelium (RPE), human RPE cell line ARPE-19, and human uveal melanoma cell line OMM-1 were used. Cell survival was assessed in tetrazolium assay (MTT). Oxidative stress assays were induced with erastin or H2O2. Supernatants were harvested to assess secreted vascular endothelial growth factor A (VEGF-A) in ELISA. Barrier function was assessed by measurement of trans-epithelial electrical resistance (TEER). Protectin (CD59) and retinal pigment epithelium-specific 65 kDa protein (RPE65) were evaluated in western blot. Polymorphonuclear elastase and complement inhibition assays were performed. Phagocytosis of photoreceptor outer segments was tested in a fluorescence assay. Secretion and expression of proinflammatory cytokines were assessed with ELISA and real-time PCR. Fucoidans were chemically analyzed. Neither toxic nor antioxidative effects were detected in ARPE-19 or OMM-1. Interleukin 8 gene expression was slightly reduced by SL-NOR but induced by SL-FRO in RPE. VEGF secretion was reduced in ARPE-19 by SL-FRO and in RPE by both fucoidans. Polyinosinic:polycytidylic acid induced interleukin 6 and interleukin 8 secretion was reduced by both fucoidans in RPE. CD59 expression was positively influenced by fucoidans, and they exhibited a complement and elastase inhibitory effect in cell-free assay. RPE65 expression was reduced by SL-NOR in RPE. Barrier function of RPE was transiently reduced. Phagocytosis ability was slightly reduced by both fucoidans in primary RPE but not in ARPE-19. Fucoidans from Saccharina latissima, especially SL-FRO, are promising agents against AMD, as they reduce angiogenic cytokines and show anti-inflammatory and complement inhibiting properties; however, potential effects on gene expression and RPE functions need to be considered for further research.
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Affiliation(s)
- Philipp Dörschmann
- Department of Ophthalmology, University Medical Center, University of Kiel, Arnold-Heller-Str. 3, Haus 25, 24105 Kiel, Germany (A.K.)
| | - Tabea Thalenhorst
- Department of Ophthalmology, University Medical Center, University of Kiel, Arnold-Heller-Str. 3, Haus 25, 24105 Kiel, Germany (A.K.)
| | - Charlotte Seeba
- Department of Ophthalmology, University Medical Center, University of Kiel, Arnold-Heller-Str. 3, Haus 25, 24105 Kiel, Germany (A.K.)
| | | | - Sandesh Neupane
- Wyatt Technology Europe GmbH, Hochstrasse 12a, 56307 Dernbach, Germany
| | - Johann Roider
- Department of Ophthalmology, University Medical Center, University of Kiel, Arnold-Heller-Str. 3, Haus 25, 24105 Kiel, Germany (A.K.)
| | - Susanne Alban
- Pharmaceutical Institute, University of Kiel, Gutenbergstr. 76, 24118 Kiel, Germany
| | - Alexa Klettner
- Department of Ophthalmology, University Medical Center, University of Kiel, Arnold-Heller-Str. 3, Haus 25, 24105 Kiel, Germany (A.K.)
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Dörschmann P, Seeba C, Thalenhorst T, Roider J, Klettner A. Anti-inflammatory properties of antiangiogenic fucoidan in retinal pigment epithelium cells. Heliyon 2023; 9:e15202. [PMID: 37123974 PMCID: PMC10130777 DOI: 10.1016/j.heliyon.2023.e15202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 03/27/2023] [Accepted: 03/29/2023] [Indexed: 05/02/2023] Open
Abstract
Age-related macular degeneration (AMD) is a multifactorial disease in which angiogenesis, oxidative stress and inflammation are important contributing factors. In this study, we investigated the anti-inflammatory effects of a fucoidan from the brown algae Fucus vesiculosus (FV) in primary porcine RPE cells. Inflammation was induced by lipopolysaccharide (LPS), polyinosinic:polycytidylic acid (Poly I:C), Pam2CSK4 (Pam), or tumor necrosis factor alpha (TNF-α). Cell viability was tested with thiazolyl blue tetrazolium bromide (MTT) test, barrier function by measuring transepithelial electric resistance (TEER), interleukin 6 (IL-6) and interleukin 8 (IL-8) secretion in ELISA, retinal pigment epithelium-specific 65 kDa protein (RPE65) and protectin (CD59) expression in Western blot, gene expression with quantitative polymerase chain reaction (qPCR) (IL6, IL8, MERTK, PIK3CA), and phagocytotic activity in a microscopic assay. FV fucoidan did not influence RPE cell viability. FV fucoidan reduced the Poly I:C proinflammatory cytokine secretion of IL-6 and IL-8. In addition, it decreased the expression of IL-6 and IL-8 in RT-PCR. LPS and TNF-α reduced the expression of CD59 in Western blot, this reduction was lost under FV fucoidan treatment. Also, LPS and TNF-α reduced the expression of visual cycle protein RPE65, this reduction was again lost under FV fucoidan treatment. Furthermore, the significant reduction of barrier function after Poly I:C stimulation is ameliorated by FV fucoidan. Concerning phagocytosis, however, the inflammation-induced reduction was not improved by FV fucoidan. FV and proinflammatory milieu did not relevantly influence phagocytosis relevant gene expression either. In conclusion, we show that fucoidan from FV can reduce proinflammatory stimulation in RPE induced by toll-like receptor 3 (TLR-3) activation and is of high interest as a potential compound for early AMD treatment.
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Wong JHC, Ma JYW, Jobling AI, Brandli A, Greferath U, Fletcher EL, Vessey KA. Exploring the pathogenesis of age-related macular degeneration: A review of the interplay between retinal pigment epithelium dysfunction and the innate immune system. Front Neurosci 2022; 16:1009599. [PMID: 36408381 PMCID: PMC9670140 DOI: 10.3389/fnins.2022.1009599] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 10/12/2022] [Indexed: 07/30/2023] Open
Abstract
Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss in the older population. Classical hallmarks of early and intermediate AMD are accumulation of drusen, a waste deposit formed under the retina, and pigmentary abnormalities in the retinal pigment epithelium (RPE). When the disease progresses into late AMD, vision is affected due to death of the RPE and the light-sensitive photoreceptors. The RPE is essential to the health of the retina as it forms the outer blood retinal barrier, which establishes ocular immune regulation, and provides support for the photoreceptors. Due to its unique anatomical position, the RPE can communicate with the retinal environment and the systemic immune environment. In AMD, RPE dysfunction and the accumulation of drusen drive the infiltration of retinal and systemic innate immune cells into the outer retina. While recruited endogenous or systemic mononuclear phagocytes (MPs) contribute to the removal of noxious debris, the accumulation of MPs can also result in chronic inflammation and contribute to AMD progression. In addition, direct communication and indirect molecular signaling between MPs and the RPE may promote RPE cell death, choroidal neovascularization and fibrotic scarring that occur in late AMD. In this review, we explore how the RPE and innate immune cells maintain retinal homeostasis, and detail how RPE dysfunction and aberrant immune cell recruitment contribute to AMD pathogenesis. Evidence from AMD patients will be discussed in conjunction with data from preclinical models, to shed light on future therapeutic targets for the treatment of AMD.
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Retinal Pigment Epithelium Expressed Toll-like Receptors and Their Potential Role in Age-Related Macular Degeneration. Int J Mol Sci 2021; 22:ijms22168387. [PMID: 34445096 PMCID: PMC8395065 DOI: 10.3390/ijms22168387] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/03/2021] [Accepted: 08/03/2021] [Indexed: 01/17/2023] Open
Abstract
(1) Background: Inflammation is a major pathomechanism in the development and progression of age-related macular degeneration (AMD). The retinal pigment epithelium (RPE) may contribute to retinal inflammation via activation of its Toll-like receptors (TLR). TLR are pattern recognition receptors that detect the pathogen- or danger-associated molecular pattern. The involvement of TLR activation in AMD is so far not understood. (2) Methods: We performed a systematic literature research, consulting the National Library of Medicine (PubMed). (3) Results: We identified 106 studies, of which 54 were included in this review. Based on these studies, the current status of TLR in AMD, the effects of TLR in RPE activation and of the interaction of TLR activated RPE with monocytic cells are given, and the potential of TLR activation in RPE as part of the AMD development is discussed. (4) Conclusion: The activation of TLR2, -3, and -4 induces a profound pro-inflammatory response in the RPE that may contribute to (long-term) inflammation by induction of pro-inflammatory cytokines, reducing RPE function and causing RPE cell degeneration, thereby potentially constantly providing new TLR ligands, which could perpetuate and, in the long run, exacerbate the inflammatory response, which may contribute to AMD development. Furthermore, the combined activation of RPE and microglia may exacerbate neurotoxic effects.
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Terheyden L, Roider J, Klettner A. Basolateral activation with TLR agonists induces polarized cytokine release and reduces barrier function in RPE in vitro. Graefes Arch Clin Exp Ophthalmol 2021; 259:413-424. [PMID: 32949301 PMCID: PMC7843481 DOI: 10.1007/s00417-020-04930-2] [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: 07/13/2020] [Revised: 08/24/2020] [Accepted: 09/10/2020] [Indexed: 01/18/2023] Open
Abstract
PURPOSE Systemic inflammation may be of importance in the development of AMD. RPE cells can recognize danger signals with toll-like receptors (TLR) and may react in a pro-inflammatory manner. In this study, we evaluated the basal and apical secretions of TNFα, IL-6, and IL-1β in primary RPE cells and RPE/choroid explant cells under basolateral stimulation of TLR2, 3, and 4; the effects on barrier function; and their influence on neuronal cell viability. METHODS RPE/choroid tissue explants were prepared from porcine eyes and cultivated in modified Ussing chambers; primary porcine RPE cells on transwell plates. Cells were basally stimulated with agonists Pam2CSK4 (Pam; TLR2), polyinosinic/polycytidylic acid (Poly I:C; TLR3), and lipopolysaccharide (LPS; TLR4) for 24 h. Supernatants were evaluated with ELISA for cytokines TNFα, IL-6, and IL-1β. Apical supernatants were applied to SHSY-5Y cells, and cell viability was evaluated in MTT assay. Barrier function was tested by measuring transepithelial electrical resistance (TER) and occludin immunostaining. RESULTS None of the tested TLR agonists was toxic on RPE cells after 24 h of exposure. Unstimulated RPE cells secreted hardly any cytokines. Pam induced IL-6, IL-1ß, and TNFα on the basal and apical sides at all concentrations tested. Poly I:C induced IL-6 and TNFα primarily at the basal side at lower but on both sides at higher concentrations. LPS induced IL-6, IL-1ß, and TNFα apically and basally at all concentrations tested. In the RPE/choroid, a strong difference between apical and basal secretions could be found. IL-6 was constitutively secreted basally, but not apically, but was induced by all agonists on both sides. IL-1ß and TNFα alpha were strongly induced on the basal side by all agonists. TER was reduced by all agonists, with Pam and LPS being effective in all concentrations tested. Occludin expression was unaltered, but the distribution was influenced by the agonists, with a less distinct localization at the cell borders after treatment. None of the agonists or supernatants of treated RPE and RPE/choroid organ cultures exerted any effect on viability of SHSY-5Y cells. CONCLUSIONS Danger signals activating TLRs can induce polarized cytokine expression and contribute to the loss of barrier function in the RPE.
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Affiliation(s)
- Laura Terheyden
- grid.9764.c0000 0001 2153 9986University Medical Center, Department of Ophthalmology, University of Kiel, Arnold-Heller-Str. 3, Haus B2, 24105 Kiel, Germany
| | - Johann Roider
- grid.9764.c0000 0001 2153 9986University Medical Center, Department of Ophthalmology, University of Kiel, Arnold-Heller-Str. 3, Haus B2, 24105 Kiel, Germany
| | - Alexa Klettner
- grid.9764.c0000 0001 2153 9986University Medical Center, Department of Ophthalmology, University of Kiel, Arnold-Heller-Str. 3, Haus B2, 24105 Kiel, Germany
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Al Sharif S, Pinto DO, Mensah GA, Dehbandi F, Khatkar P, Kim Y, Branscome H, Kashanchi F. Extracellular Vesicles in HTLV-1 Communication: The Story of an Invisible Messenger. Viruses 2020; 12:E1422. [PMID: 33322043 PMCID: PMC7763366 DOI: 10.3390/v12121422] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/07/2020] [Accepted: 12/08/2020] [Indexed: 02/08/2023] Open
Abstract
Human T-cell lymphotropic virus type 1 (HTLV-1) infects 5-10 million people worldwide and is the causative agent of adult T-cell leukemia/lymphoma (ATLL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) as well as other inflammatory diseases. A major concern is that the most majority of individuals with HTLV-1 are asymptomatic carriers and that there is limited global attention by health care officials, setting up potential conditions for increased viral spread. HTLV-1 transmission occurs primarily through sexual intercourse, blood transfusion, intravenous drug usage, and breast feeding. Currently, there is no cure for HTLV-1 infection and only limited treatment options exist, such as class I interferons (IFN) and Zidovudine (AZT), with poor prognosis. Recently, small membrane-bound structures, known as extracellular vesicles (EVs), have received increased attention due to their potential to carry viral cargo (RNA and proteins) in multiple pathogenic infections (i.e., human immunodeficiency virus type I (HIV-1), Zika virus, and HTLV-1). In the case of HTLV-1, EVs isolated from the peripheral blood and cerebral spinal fluid (CSF) of HAM/TSP patients contained the viral transactivator protein Tax. Additionally, EVs derived from HTLV-1-infected cells (HTLV-1 EVs) promote functional effects such as cell aggregation which enhance viral spread. In this review, we present current knowledge surrounding EVs and their potential role as immune-modulating agents in cancer and other infectious diseases such as HTLV-1 and HIV-1. We discuss various features of EVs that make them prime targets for possible vehicles of future diagnostics and therapies.
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Affiliation(s)
| | | | | | | | | | | | | | - Fatah Kashanchi
- Laboratory of Molecular Virology, George Mason University, Manassas, VA 20110, USA; (S.A.S.); (D.O.P.); (G.A.M.); (F.D.); (P.K.); (Y.K.); (H.B.)
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Al-Ani A, Sunba S, Hafeez B, Toms D, Ungrin M. In Vitro Maturation of Retinal Pigment Epithelium Is Essential for Maintaining High Expression of Key Functional Genes. Int J Mol Sci 2020; 21:ijms21176066. [PMID: 32842471 PMCID: PMC7503905 DOI: 10.3390/ijms21176066] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/08/2020] [Accepted: 08/19/2020] [Indexed: 12/03/2022] Open
Abstract
Age-related macular degeneration (AMD) is the leading cause of blindness in the industrialized world. AMD is associated with dysfunction and atrophy of the retinal pigment epithelium (RPE), which provides critical support for photoreceptor survival and function. RPE transplantation is a promising avenue towards a potentially curative treatment for early stage AMD patients, with encouraging reports from animal trials supporting recent progression toward clinical treatments. Mature RPE cells have been reported to be superior, but a detailed investigation of the specific changes in the expression pattern of key RPE genes during maturation is lacking. To understand the effect of maturity on RPE, we investigated transcript levels of 19 key RPE genes using ARPE-19 cell line and human embryonic stem cell-derived RPE cultures. Mature RPE cultures upregulated PEDF, IGF-1, CNTF and BDNF—genes that code for trophic factors known to enhance the survival and function of photoreceptors. Moreover, the mRNA levels of these genes are maximized after 42 days of maturation in culture and lost upon dissociation to single cells. Our findings will help to inform future animal and human RPE transplantation efforts.
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Affiliation(s)
- Abdullah Al-Ani
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada; (A.A.-A.); (S.S.); (B.H.); (M.U.)
- Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G 2E1, Canada
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB T2N 1N4, Canada
- Leaders in Medicine Program, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Saud Sunba
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada; (A.A.-A.); (S.S.); (B.H.); (M.U.)
| | - Bilal Hafeez
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada; (A.A.-A.); (S.S.); (B.H.); (M.U.)
| | - Derek Toms
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada; (A.A.-A.); (S.S.); (B.H.); (M.U.)
- Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
- Correspondence:
| | - Mark Ungrin
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada; (A.A.-A.); (S.S.); (B.H.); (M.U.)
- Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G 2E1, Canada
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB T2N 1N4, Canada
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Dietrich L, Lucius R, Roider J, Klettner A. Interaction of inflammatorily activated retinal pigment epithelium with retinal microglia and neuronal cells. Exp Eye Res 2020; 199:108167. [PMID: 32735798 DOI: 10.1016/j.exer.2020.108167] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 07/10/2020] [Accepted: 07/21/2020] [Indexed: 12/30/2022]
Abstract
In age-related macular degeneration, inflammatory events are presumed to contribute to disease development. A primary suspect of this contribution is the microglia, the innate immune cell of the retina. In addition, retinal pigment epithelium (RPE) cells can be inflammatorily activated. In this study, we investigate the effect of activated RPE cells on retinal microglia and on neuronal cells. RPE cells and microglia were harvested from porcine eyes. In addition, a neuronal cell line (SHSY-5Y) of human origin was used. For inflammatory activation, agonists of toll-like receptors in different concentrations were used: Pam2CSK4 (Pam; TLR-2), Polyinosinic:polycytidylic acid (Poly I:C; TLR-3) and lipopolysaccharid (LPS; TLR-4). Cell viability was investigated with an MTT assay. The secretion of cytokines was assessed in an ELISA and their expression in real-time PCR. There was no effect of the agonists on cell viability in RPE cells. All agonists induced the secretion of IL-6 and IL-8 in RPE cells with the strongest effect induced by LPS. In microglia, pro-inflammatory stimulation increased the metabolic activity. All agonists induced the secretion of IL-1ß, IL-8, and TNFα in microglia cells while in real-time PCR, LPS and Pam induced the expression of IL-6, IL-1ß and iNOS. Direct stimulation of SHSY-5Y with the agonists induced only minor alterations of viability. Stimulated RPE cell supernatant reduced the secretion of TNFα and IL-8 irrespective of the inducing agent in microglia cells. Additionally a slight induction of IL-1ß was found in microglia treated with supernatant of RPE cells treated with Pam. In real time PCR, the supernatant of RPE cells stimulated with LPS significantly reduced the expression of iNOS and IL-6, but not of IL-1ß. Of note, the expression of iNOS was also reduced by naive RPE cells. The treatment of the SHSY-5Y with supernatant of microglia previously treated with RPE conditioned medium significantly decreased SHSY-5Y viability with and without pro-inflammatory treatment. In conclusion, inflammatory activated RPE cells have a regulatory effect on the pro-inflammatory activation of microglia, stressing the importance of the interaction between these two retinal cell types. Microglia treated with RPE supernatant reduced viability of a neuronal cell line, indicating a neurotoxic effect.
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Affiliation(s)
- Luisa Dietrich
- University of Kiel, University Medical Center, Department of Ophthalmology, Kiel, Germany
| | - Ralph Lucius
- University of Kiel, Anatomical Institute, Kiel, Germany
| | - Johann Roider
- University of Kiel, University Medical Center, Department of Ophthalmology, Kiel, Germany
| | - Alexa Klettner
- University of Kiel, University Medical Center, Department of Ophthalmology, Kiel, Germany.
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Schnichels S, Paquet-Durand F, Löscher M, Tsai T, Hurst J, Joachim SC, Klettner A. Retina in a dish: Cell cultures, retinal explants and animal models for common diseases of the retina. Prog Retin Eye Res 2020; 81:100880. [PMID: 32721458 DOI: 10.1016/j.preteyeres.2020.100880] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 06/23/2020] [Accepted: 06/26/2020] [Indexed: 12/11/2022]
Abstract
For many retinal diseases, including age-related macular degeneration (AMD), glaucoma, and diabetic retinopathy (DR), the exact pathogenesis is still unclear. Moreover, the currently available therapeutic options are often unsatisfactory. Research designed to remedy this situation heavily relies on experimental animals. However, animal models often do not faithfully reproduce human disease and, currently, there is strong pressure from society to reduce animal research. Overall, this creates a need for improved disease models to understand pathologies and develop treatment options that, at the same time, require fewer or no experimental animals. Here, we review recent advances in the field of in vitro and ex vivo models for AMD, glaucoma, and DR. We highlight the difficulties associated with studies on complex diseases, in which both the initial trigger and the ensuing pathomechanisms are unclear, and then delineate which model systems are optimal for disease modelling. To this end, we present a variety of model systems, ranging from primary cell cultures, over organotypic cultures and whole eye cultures, to animal models. Specific advantages and disadvantages of such models are discussed, with a special focus on their relevance to putative in vivo disease mechanisms. In many cases, a replacement of in vivo research will mean that several different in vitro models are used in conjunction, for instance to analyze and validate causative molecular pathways. Finally, we argue that the analytical decomposition into appropriate cell and tissue model systems will allow making significant progress in our understanding of complex retinal diseases and may furthermore advance the treatment testing.
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Affiliation(s)
- Sven Schnichels
- University Eye Hospital, Centre for Ophthalmology, University of Tübingen, Germany.
| | - François Paquet-Durand
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Germany
| | - Marina Löscher
- University Eye Hospital, Centre for Ophthalmology, University of Tübingen, Germany
| | - Teresa Tsai
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, Germany
| | - José Hurst
- University Eye Hospital, Centre for Ophthalmology, University of Tübingen, Germany
| | - Stephanie C Joachim
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, Germany
| | - Alexa Klettner
- Department of Ophthalmology, University Medical Center, University of Kiel, Kiel, Germany
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Knickelbein JE, Liu B, Arakelyan A, Zicari S, Hannes S, Chen P, Li Z, Grivel JC, Chaigne-Delalande B, Sen HN, Margolis L, Nussenblatt RB. Modulation of Immune Responses by Extracellular Vesicles From Retinal Pigment Epithelium. Invest Ophthalmol Vis Sci 2017; 57:4101-7. [PMID: 27537259 PMCID: PMC4991022 DOI: 10.1167/iovs.15-18353] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Purpose Extracellular vesicles (EV), such as exosomes, are important mediators of intercellular communication and have been implicated in modulation of the immune system. We investigated if EV released from retinal pigment epithelium (RPE) modulate immune responses in vitro. Methods Extracellular vesicles were isolated from ARPE-19 cultures stimulated or not with the inflammatory cytokines IL-1β, IFN-γ, and TNF-α. Isolated EV were characterized by nanoparticle flow and Western blot analyses. Retinal pigment epithelium–derived EV were cultured with human peripheral blood mononuclear cells, which were assayed for T-cell proliferation by 3H-thymidine incorporation. Retinal pigment epithelium–derived EV were also independently cultured with enriched lymphocytes or monocytes. Cell phenotype and cell death were evaluated by flow cytometric analysis. Cytokine levels were assayed in culture supernatants by multiplex bead analysis. Results The concentration of ARPE-derived EV from cytokine-stimulated cultures was slightly higher than from nonstimulated cultures. The size of EV was approximately 100 nm in both groups. Extracellular vesicles from both nonstimulated and cytokine-stimulated ARPE-19 significantly inhibited T-cell proliferation without affecting T-cell viability. Culture of EV from nonstimulated ARPE-19 with undifferentiated human monocytes induced an immunoregulatory phenotype with a significantly higher percentage of CD14++CD16+ monocytes and upregulation of TGF-β1. Culture of EV from cytokine-stimulated ARPE-19 cells with human monocytes induced upregulation of several proinflammatory cytokines and monocyte death. Conclusions Retinal pigment epithelium cells constitutively secrete EV in the size range of exosomes, with increased release from RPE cells stimulated with inflammatory cytokines. Extracellular vesicles from both nonstimulated and cytokine-stimulated RPE inhibited T-cell stimulation. Extracellular vesicles from nonstimulated ARPE-19 cells promoted an immunoregulatory CD14++CD16+ phenotype in human monocytes, while EV from cytokine-stimulated ARPE-19 cells caused human monocyte death. These findings suggest that RPE cells use EV to induce a downregulatory immune environment under homeostatic conditions. In an inflammatory milieu, RPE-derived EV may mitigate a potentially harmful inflammatory response through killing of monocytes.
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Affiliation(s)
- Jared E Knickelbein
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Baoying Liu
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Anush Arakelyan
- Section of Intercellular Interactions, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, United States
| | - Sonia Zicari
- Section of Intercellular Interactions, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, United States
| | - Susan Hannes
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Ping Chen
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Zhiyu Li
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Jean-Charles Grivel
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 2Section of Intercellular Interactions, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, Bethesda, Maryland
| | - Benjamin Chaigne-Delalande
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - H Nida Sen
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Leonid Margolis
- Section of Intercellular Interactions, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, United States
| | - Robert B Nussenblatt
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
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