Long-term clinical effects of epalrestat, an aldose reductase inhibitor, on diabetic peripheral neuropathy: the 3-year, multicenter, comparative Aldose Reductase Inhibitor-Diabetes Complications Trial

Emerging Therapies for Charcot-Marie-Tooth Inherited Neuropathies

Inherited neuropathies known as Charcot-Marie-Tooth (CMT) disease are genetically heterogeneous disorders affecting the peripheral nerves, causing significant and slowly progressive disability over the lifespan. The discovery of their diverse molecular genetic mechanisms over the past three decades has provided the basis for developing a wide range of therapeutics, leading to an exciting era of finding treatments for this, until now, incurable group of diseases. Many treatment approaches, including gene silencing and gene replacement therapies, as well as small molecule treatments are currently in preclinical testing while several have also reached clinical trial stage. Some of the treatment approaches are disease-specific targeted to the unique disease mechanism of each CMT form, while other therapeutics target common pathways shared by several or all CMT types. As promising treatments reach the stage of clinical translation, optimal outcome measures, novel biomarkers and appropriate trial designs are crucial in order to facilitate successful testing and validation of novel treatments for CMT patients.

Evolving concepts on the role of dyslipidemia, bioenergetics, and inflammation in the pathogenesis and treatment of diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN) is one of the most widespread and disabling neurological conditions, accounting for half of all neuropathy cases worldwide. Despite its high prevalence, no approved disease modifying therapies exist. There is now a growing body of evidence that DPN secondary to type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) represents different disease processes, with T2DM DPN best understood within the context of metabolic syndrome rather than hyperglycemia. In this review, we highlight currently understood mechanisms of DPN, along with their corresponding potential therapeutic targets. We frame this discussion within a practical overview of how the field evolved from initial human observations to murine pathomechanistic and therapeutic models into ongoing and human clinical trials, with particular emphasis on T2DM DPN and metabolic syndrome.

Diabetic nephropathy: A twisted thread to unravel

Diabetic nephropathy (DN), a persistent microvascular problem of diabetes mellitus is described as an elevated level of albumin excretion in urine and impaired renal activity. The morbidity and mortality of type-1 diabetics and type-2 diabetics due to end stage renal disease is also a result of the increased prevalence of DN. DN typically occurs as a consequence of an association among metabolic and hemodynamic variables, activating specific pathways leading to renal injury. According to current interventions, intensive glucose regulation decreases the threat of DN incidence and growth, and also suppressing the renin-angiotensin system (RAS) is a significant goal for hemodynamic and metabolism-related deformities in DN. However, the pathogenesis of DN is multifactorial so novel approaches other than glucose and blood pressure control are required for treatment. This review briefly summarizes the reported pathogenesis of DN, current interventions for its treatment, and possible novel interventions to unweave the thread of DN.

Role of Cys-298 in specific recognition of glutathione by aldose reductase

Aldose reductase (AR) is an NADPH-dependent oxidoreductase that is well-studied for its role in Diabetes Mellitus. Glutathione conjugated aldehydes are efficiently catalysed by AR. We have employed molecular dynamics simulations to investigate the dynamics of a glutathione analog, γ-glutamyl-S-(1,2-di-carboxyethyl)-cysteinyl-glycine (DCEG), into the binding pocket of AR. Study revealed that backbone nitrogens of Ala-299 and Leu-300 form a tiny pocket gated by thiol group of Cys-298. The glycine moiety of DCEG was able to displace the thiol group of Cys-298 to make hydrogen bond interactions with backbone of Ala-299, Leu-300, and Leu-301. This study provides the details of the dynamic interactions of DCEG in the binding pocket of AR, and shall aid in the design/discovery of differential inhibitors against AR.Communicated by Ramaswamy H. Sarma.

Epalrestat suppresses cadmium-induced cytotoxicity through Nrf2 in endothelial cells

Cadmium (Cd) is an industrial and environmental pollutant that targets the vascular endothelium. The vascular system is critically affected by Cd toxicity. Recent studies have indicated an association between Cd and vascular diseases, although the mechanisms of Cd implications in vascular diseases are not clear. The purpose of the present study was to determine whether epalrestat (EPS), which is used for the treatment of diabetic neuropathy, protects against Cd-induced cytotoxicity in bovine aortic endothelial cells (BAECs). In the present study, the effects of EPS at near-plasma concentration were examined on Cd-induced cytotoxicity in BAECs. Cd-induced cytotoxicity was suppressed by pretreatment with EPS. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor that serves a role in regulating the expression of glutamate cysteine ligase, the rate-limiting enzyme in glutathione (GSH) synthesis. In a previous study, EPS was demonstrated to increase GSH levels in BAECs in association with the Nrf2 pathway. In the present study, EPS increased GSH levels in BAECs exposed to Cd. The protective ability of EPS against the Cd-induced cytotoxicity disappeared following Nrf2 small interfering RNA transfection. In addition, EPS affected the intracellular levels of Cd, Cd transporter ZIP8 and metallothionein. To the best of our knowledge, the current study demonstrated, for the first time, that EPS suppresses Cd-induced cytotoxicity in BAECs. The upregulation of GSH may be associated with the suppression of Cd-induced cytotoxicity by EPS. From these findings, it may be proposed that the regulation of GSH, ZIP8 and metallothionein by EPS is a promising therapeutic approach to prevent Cd-induced toxicity.

Natural antioxidants in diabetes treatment and management: prospects of astaxanthin

Diabetes remains a major health emergency in our entire world, affecting hundreds of millions of people worldwide. In conjunction with its much-dreaded complications (e.g., nephropathy, neuropathy, retinopathy, cardiovascular diseases, etc.) it substantially reduces the quality of life, increases mortality as well as economic burden among patients. Over the years, oxidative stress and inflammation have been highlighted as key players in the development and progression of diabetes and its associated complications. Much research has been devoted, as such, to the role of antioxidants in diabetes. Astaxanthin is a powerful antioxidant found mostly in marine organisms. Over the past years, several studies have demonstrated that astaxanthin could be useful in the treatment and management of diabetes. It has been shown to protect β-cells, neurons as well as several organs including the eyes, kidney, liver, etc. against oxidative injuries experienced during diabetes. Furthermore, it improves glucose and lipid metabolism along with cardiovascular health. Its beneficial effects are exerted through multiple actions on cellular functions. Considering these and the fact that foods and natural products with biological and pharmacological activities are of much interest in the 21st-century food and drug industry, astaxanthin has a bright prospect in the management of diabetes and its complications.

Glucagon Prevents Cytotoxicity Induced by Methylglyoxal in a Rat Neuronal Cell Line Model

Although diabetic polyneuropathy (DPN) is a frequent diabetic complication, no effective therapeutic approach has been established. Glucagon is a crucial hormone for glucose homeostasis but has pleiotropic effects, including neuroprotective effects in the central nervous system. However, the importance of glucagon in the peripheral nervous system (PNS) has not been clarified. Here, we hypothesized that glucagon might have a neuroprotective function in the PNS. The immortalized rat dorsal root ganglion (DRG) neuronal cell line 50B11 was treated with methylglyoxal (MG) to mimic an in vitro DPN model. The cells were cultured with or without glucagon or MG. Neurotoxicity, survival, apoptosis, neurite projection, cyclic adenosine monophosphate (cAMP), and protein kinase A (PKA) were examined. Glucagon had no cytotoxicity and rescued the cells from neurotoxicity. Cell survival was increased by glucagon. The ratio of apoptotic cells, which was increased by MG, was reduced by glucagon. Neurite outgrowth was accelerated in glucagon-treated cells. Cyclic AMP and PKA accumulated in the cells after glucagon stimulation. In conclusion, glucagon protected the DRG neuronal cells from MG-induced cellular stress. The cAMP/PKA pathway may have significant roles in those protective effects of glucagon. Glucagon may be a potential target for the treatment of DPN.

The time to develop treatments for diabetic neuropathy

BACKGROUND

Diabetic neuropathy is a multifaceted condition affecting up to 50% of individuals with long standing diabetes. The most common presentation is peripheral diabetic sensory neuropathy (DPN).

METHODS

We carried out a systematic review of papers dealing with diabetic neuropathy on Pubmed in addition to a targeted Google search.Search terms included small fiber neuropathy,diffuse peripheral neuropathy, quantitative sensory testing, nerve conduction testing, intra-epidermal nerve fiber density, corneal confocal reflectance microscopy, aldose reductase inhbitors, nerve growth factor, alpha-lipoic acid, ruboxistaurin, nerve growth factor antibody, and cibinetide.

RESULTS

Over the past half century, there have been a number of agents undergoing unsuccessful trials for treatment of DPN.There are several approved agents for relief of pain caused by diabetic neuropathy, but these do not affect the pathologic process.

EXPERT OPINION

The failure to find treatments for diabetic neuropathy can be ascribed to (1) the complexity of design of studies and (2) the slow progression of the condition, necessitating long duration trials to prove efficacy.We propose a modification of the regulatory process to permit early introduction of agents with demonstrated safety and suggestion of benefit as well as prolongation of marketing exclusivity while long term trials are in progress to prove efficacy.

Pathogenesis and Molecular Treatment Strategies of Diabetic Neuropathy Collateral Glucose-Utilizing Pathways in Diabetic Polyneuropathy

Diabetic polyneuropathy (DPN) is the most common neuropathy manifested in diabetes. Symptoms include allodynia, pain, paralysis, and ulcer formation. There is currently no established radical treatment, although new mechanisms of DPN are being vigorously explored. A pathophysiological feature of DPN is abnormal glucose metabolism induced by chronic hyperglycemia in the peripheral nerves. Particularly, activation of collateral glucose-utilizing pathways such as the polyol pathway, protein kinase C, advanced glycation end-product formation, hexosamine biosynthetic pathway, pentose phosphate pathway, and anaerobic glycolytic pathway are reported to contribute to the onset and progression of DPN. Inhibitors of aldose reductase, a rate-limiting enzyme involved in the polyol pathway, are the only compounds clinically permitted for DPN treatment in Japan, although their efficacies are limited. This may indicate that multiple pathways can contribute to the pathophysiology of DPN. Comprehensive metabolic analysis may help to elucidate global changes in the collateral glucose-utilizing pathways during the development of DPN, and highlight therapeutic targets in these pathways.

Current concepts in the management of diabetic polyneuropathy

Diabetic sensorimotor polyneuropathy (DSPN) is encountered in approximately one-third of people with diabetes. This, in turn, might markedly impoverish their quality of life, mainly owing to neuropathic pain and foot ulcerations. Painful DSPN might be as frequent as 25% in diabetes patients. Symptoms as a result of DSPN typically comprise pain, paresthesia and numbness in the distal lower limbs. Asymptomatic DSPN might reach 50% among patients with this condition. Unfortunately, DSPN is still not adequately diagnosed and treated. Its management has three priorities: (i) lifestyle improvement, near-normoglycemia and multifactorial cardiovascular risk intervention; (ii) pathogenesis-oriented pharmacotherapy; and (iii) symptomatic alleviation of pain. Intensive diabetes therapy showed evidence for favorable effects on the incidence and deterioration of DSPN in type 1 diabetes, but not type 2 diabetes. Among pathogenesis-oriented treatments, α-lipoic acid, actovegin, benfotiamine and epalrestat are currently authorized to treat DSPN in several countries. Symptomatic therapy uses analgesics, notably antidepressants, opioids and anticonvulsants, reducing pain by ≥50% in approximately 50% of individuals, but might be limited, particularly by central nervous system-related adverse events. Local treatment with the capsaicin 8% patch might offer an alternative. In addition to pain relief, therapy should improve sleep, mobility and quality of life. In conclusion, multimodal treatment of DSPN should consider the individual risk profile, pathogenetic treatment and pain management using pharmacotherapy (combinations, if required), as well as non-pharmacological options.

Role of glucosamine in development of diabetic neuropathy independent of the aldose reductase pathway

Long-term metabolic aberrations contribute to the development of diabetic neuropathy but the precise mechanism or mechanisms remains elusive. We have previously shown that aldose reductase-deficient mice exhibit delayed onset and progression of neuropathy following induction of diabetes, suggesting a role both for downstream metabolites of this enzyme and also for other unrelated pathways. In this study, we have utilized comprehensive metabolomics analyses to identify potential neurotoxic metabolites in nerve of diabetic mice and explored the mechanism of peripheral nerve injury. Aldose reductase knockout and control C57Bl/6J mice were made diabetic by injection of streptozotocin and followed for 8–16 weeks. Diabetic aldose reductase knockout mice exhibited delayed onset of nerve conduction slowing compared to diabetic wild-type mice. The sciatic nerves from aldose reductase knockout mice exposed to 12 weeks of diabetes were used for metabolomics analysis and compared with analyses of nerves from age-matched diabetic wild-type mice as well as non-diabetic aldose reductase knockout and wild-type mice. Neurotoxicity of candidate metabolites was evaluated using cultured Schwann cells and dorsal root ganglion neurons, and further confirmed in vivo. Metabolomics analysis identified elevated glucosamine levels in both diabetic aldose reductase knockout and diabetic wild mice. Exposure to glucosamine reduced survival of cultured Schwann cells and neurons accompanied by increased expression of cleaved caspase 3, CCAT-enhancer-binding homologous protein and mitochondrial hexokinase-I, along with ATP depletion. These changes were suppressed by siRNA to hexokinase-I or the ATP donor, inosine, but not by the antioxidant N-acetylcysteine or the endoplasmic reticulum-stress inhibitor 4-phenylbutyrate. The O-GlcNAcylation enhancer, O-(2-acetamido-2-deoxy-d-glucopyranosylidene) amino N-phenylcarbamate, did not augment glucosamine neurotoxicity. Single dose glucosamine injection into mice caused a reduction of sciatic nerve Na, K-ATPase activity, ATP content and augmented expression of hexokinase-I, which were suppressed by pretreatment with inosine but not with 4-phenylbutyrate. Mice implanted with a subcutaneous pump to infuse glucosamine for 12 weeks developed nerve conduction slowing and intraepidermal nerve fibre loss, recapitulating prominent indices of diabetic neuropathy. While acute glucosamine neurotoxicity is unlikely to contribute substantially to the slowly developing neuropathy phenotype in humans, sustained energy deprivation induced by glucosamine may well contribute to the pathogenesis of diabetic neuropathy. Our data thus identifies a novel pathway for diabetic neuropathy that may offer a potential new therapeutic target.

Antispasmodic Drug Drofenine as an Inhibitor of Kv2.1 Channel Ameliorates Peripheral Neuropathy in Diabetic Mice

Diabetic peripheral neuropathy (DPN) is a common diabetic complication and has yet no efficient medication. Here, we report that antispasmodic drug drofenine (Dfe) blocks Kv2.1 and ameliorates DPN-like pathology in diabetic mice. The underlying mechanisms are investigated against the DPN mice with in vivo Kv2.1 knockdown through adeno associated virus AAV9-Kv2.1-RNAi. Streptozotocin (STZ) induced type 1 or db/db type 2 diabetic mice with DPN exhibited a high level of Kv2.1 protein in dorsal root ganglion (DRG) tissue and a suppressed neurite outgrowth in DRG neuron. Dfe promoted neurite outgrowth by inhibiting Kv2.1 channel and/or Kv2.1 mRNA and protein expression level. Moreover, it suppressed inflammation by repressing IκBα/NF-κB signaling, inhibited apoptosis by regulating Kv2.1-mediated Bcl-2 family proteins and Caspase-3 and ameliorated mitochondrial dysfunction through Kv2.1/CaMKKβ/AMPK/PGC1α pathway. Our work supports that Kv2.1 inhibition is a promisingly therapeutic strategy for DPN and highlights the potential of Dfe in treating this disease.

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Antispasmodic drug drofenine (Dfe) ameliorates DPN-like pathology in diabetic mice

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Dfe inhibits Kv2.1 channel and/or Kv2.1 mRNA and protein expression level

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Dfe represses inflammation, apoptosis, and mitochondrial dysfunction in DPN mice

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Kv2.1 inhibition is a therapeutic tactic and Dfe shows therapeutic potential for DPN

Direct Comparison of Therapeutic Effects on Diabetic Polyneuropathy between Transplantation of Dental Pulp Stem Cells and Administration of Dental Pulp Stem Cell-Secreted Factors

Stem cell transplantation is a potential novel therapy for diabetic polyneuropathy. Dental pulp stem cells (DPSCs) are attractive stem cell sources because DPSCs can be isolated from extracted teeth and cryopreserved while retaining viability. In this study, we directly compared the efficacy of the transplantation of DPSCs and the administration of the secreted factors from DPSCs (DPSC-SFs) on diabetic polyneuropathy. Eight weeks after streptozotocin injection, DPSCs (1.0 × 10⁶ cells/rat) or DPSC-SFs (1.0 mL/rat) were administered into the unilateral hindlimb skeletal muscles of diabetic Sprague-Dawley rats. DPSC transplantation and DPSC-SF administration did not affect blood glucose levels and body weights in the diabetic rats. Both DPSC transplantation and DPSC-SF administration significantly ameliorated sciatic nerve conduction velocity and sciatic nerve blood flow, accompanied by increases in muscle bundle size, vascular density in the skeletal muscles and intraepidermal nerve fiber density in the diabetic rats, while there was no difference between the results for DPSCs and DPSC-SFs. These results suggest that the efficacy of both DPSC transplantation and DPSC-SF administration for diabetic polyneuropathy four weeks after transplantation/administration was mainly due to the multiple secretomes secreted from transplanted DPSCs or directly injected DPSC-SFs in the early phase of transplantation/administration.

Efficacy and tolerability of DPP4 inhibitor, teneligliptin, on autonomic and peripheral neuropathy in type 2 diabetes: an open label, pilot study

BACKGROUND

Diabetic neuropathy increases risk of cardiovascular disease, peripheral artery disease, foot amputation and overall mortality. Not only hyperglycaemia induced nerve damage is harder to repair using currently approved medications, but also, the use of these agents is often limited by the extent of pain relief provided and side effects.

METHODOLOGY

In this prospective, open-label, pilot study, 20 type-2 diabetes mellitus patients (male/female=13/7, mean age- 56.1±8.04 years), meeting inclusion/exclusion criteria, were treated with dipeptidyl peptidase-4 (DPP-4) inhibitor, Teneligliptin, 20mg once a day for three months. Efficacy parameters: Sudomotor function (Sudoscan score); parasympathetic dysfunction assessed using Ewing's criteria i.e. heart rate response to -standing (HRS), -valsalva (HRV) and -deep breath (HRD); sympathetic dysfunction assessed as blood pressure response to -standing (BPS) and -handgrip (BPH); ankle brachial index (ABI), vibration perception threshold (VPT), C-reactive protein, glycemic profile and health related quality of life (HRQoL); and, tolerability parameters: complete blood count, liver function tests, serum creatinine, thyroid stimulating hormone, QT- interval and serum vitamin B12 levels, were measured.

RESULTS

There was no statistical difference in BMI, SBP, DBP, HRD, BPH and all safety parameters. After 12 weeks treatment, there was improvement in HRS (p<0.01) and HRV (p<0.01), but not in HRD (p=0.12). BPS was significantly lowered (p <0.01), but not the BPH (p =0.06). Sudoscan score was increased, while VPT was significantly decreased (both p<0.01).

CONCLUSION

Teneligliptin not only improves the glycemic status but also improves sudomotor function, peripheral and autonomic neuropathy, and reduces vascular inflammation in type 2 diabetes.

Diabetic Peripheral Neuropathy: Diagnosis and Treatment

BACKGROUND

Diabetic peripheral neuropathy (DPN) is traditionally divided into large and small fibre neuropathy (SFN). Damage to the large fibres can be detected using nerve conduction studies (NCS) and often results in a significant reduction in sensitivity and loss of protective sensation, while damage to the small fibres is hard to reliably detect and can be either asymptomatic, associated with insensitivity to noxious stimuli, or often manifests itself as intractable neuropathic pain.

OBJECTIVE

To describe the recent advances in both detection, grading, and treatment of DPN as well as the accompanying neuropathic pain.

METHODS

A review of relevant, peer-reviewed, English literature from MEDLINE, EMBASE and Cochrane Library between January 1st 1967 and January 1st 2020 was used.

RESULTS

We identified more than three hundred studies on methods for detecting and grading DPN, and more than eighty randomised-controlled trials for treating painful diabetic neuropathy.

CONCLUSION

NCS remains the method of choice for detecting LFN in people with diabetes, while a gold standard for the detection of SFN is yet to be internationally accepted. In the recent years, several methods with huge potential for detecting and grading this condition have become available including skin biopsies and corneal confocal microscopy, which in the future could represent reliable endpoints for clinical studies. While several newer methods for detecting SFN have been developed, no new drugs have been accepted for treating neuropathic pain in people with diabetes. Tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors and anticonvulsants remain first line treatment, while newer agents targeting the proposed pathophysiology of DPN are being developed.

A Systematic Review on Anti-diabetic Properties of Chalcones

The use of anti-diabetic drugs has been increasing worldwide and the evolution of therapeutics has been enormous. Still, the currently available anti-diabetic drugs do not present the desired efficacy and are generally associated with serious adverse effects. Thus, entirely new interventions, addressing the underlying etiopathogenesis of type 2 diabetes mellitus, are required. Chalcones, secondary metabolites of terrestrial plants and precursors of the flavonoids biosynthesis, have been used for a long time in traditional medicine due to their wide-range of biological activities, from which the anti-diabetic activity stands out. This review systematizes the information found in literature about the anti-diabetic properties of chalcones, in vitro and in vivo. Chalcones are able to exert these properties by acting in different therapeutic targets: Dipeptidyl Peptidase 4 (DPP-4); Glucose Transporter Type 4 (GLUT4), Sodium Glucose Cotransporter 2 (SGLT2), α-amylase, α-glucosidase, Aldose Reductase (ALR), Protein Tyrosine Phosphatase 1B (PTP1B), Peroxisome Proliferator-activated Receptor-gamma (PPARγ) and Adenosine Monophosphate (AMP)-activated Protein Kinase (AMPK). Chalcones are, undoubtedly, promising anti-diabetic agents, and some crucial structural features have already been established. From the Structure-Activity Relationships analysis, it can generally be stated that the presence of hydroxyl, prenyl and geranyl groups in their skeleton improves their activity for the evaluated anti-diabetic targets.

New and potential strategies for the treatment of PMM2-CDG

BACKGROUND

Mutations in the PMM2 gene cause phosphomannomutase 2 deficiency (PMM2; MIM# 212065), which manifests as a congenital disorder of glycosylation (PMM2-CDG). Mutant PMM2 leads to the reduced conversion of Man-6-P to Man-1-P, which results in low concentrations of guanosine 5'-diphospho-D-mannose, a nucleotide-activated sugar essential for the construction of protein oligosaccharide chains. To date the only therapeutic options are preventive and symptomatic.

SCOPE OF REVIEW

This review covers the latest advances in the search for a treatment for PMM2-CDG.

MAJOR CONCLUSIONS

Treatments based on increasing Man-1-P levels have been proposed, along with the administration of different mannose derivates, employing enzyme inhibitors or repurposed drugs to increase the synthesis of GDP-Man. A single repurposed drug that might alleviate a severe neurological symptom associated with the disorder is now in clinical use. Proof of concept also exists regarding the use of pharmacological chaperones and/or proteostatic regulators to increase the concentration of hypomorphic PMM2 mutant proteins.

GENERAL SIGNIFICANCE

The ongoing challenges facing the discovery of drugs to treat this orphan disease are discussed.

A three-dimensional biomimetic peripheral nerve model for drug testing and disease modelling

In vitro peripheral nerve models provide valuable tools to study neurobiology questions and assess drug performance, in a regenerative or pathology context. To this end, we have developed a representative model of the peripheral nerve that displays three-dimensional (3D) neural anisotropy and myelination, which we showcase here as a simple and low-cost platform for drug screening. The model is composed of three main parts, including rat primary Schwann cells (SCs) seeded onto an electrospun scaffold to create bands of Büngner (BoB), primed PC12 cells as neuronal cell population, and a fibrin hydrogel to provide three-dimensionality. We also validated the use of primed PC12 as a neuron population by comparing it to rat dorsal root ganglions (DRGs) neurons. In both models we could obtain well aligned neurites and mature myelin segments. In short term cultures (7 days), we found that the addition of exogenous SCs enhanced neurite length and neurite growth area, compared to scaffolds with a laminin coating only. Addition of fibrin also lead to increased outgrowth of DRG and primed PC12 neurites, compared to 2D cultures. Moreover, neurite outgrowth in fibrin cultures was simultaneously multiplanar and anisotropic, suggesting that the SC-seeded scaffold can direct not only the growth of adjacent neurites, but also those growing above it. These results highlight the feasibility of the combination of a SC pre-seeded scaffold with a fibrin hydrogel, to direct and improve neurite growth in 3D. To demonstrate the model potential, we tested our platform at an immature (7 days in vitro) and mature state (28 days in vitro) of development. At the immature stage we could inhibit neurite growth through protein blocking (via antibody binding) and show suramin (200 μM) neurotoxicity on cells. At the mature stage, when myelin is compact, we exposed cells to hyperglycemic conditions (45 mM glucose) to mimic diabetic conditions and showed that myelin deforms consequently. Moreover, we demonstrated that by supplementing cultures with epalrestat (1 μM), myelin deformation can be partly prevented. In sum, we developed a biomimetic nerve platform using an affordable and accessible cell line as neuronal population, which displays similar results to primary neurons, but does not require recurrent animal sacrifice. This platform holds great promise as it can be used to conveniently and inexpensively perform drug screenings on peripheral nerve-like tissue, in a normal or pathological state.

Kaempferol Rhamnosides from Geranium sibiricum as Aldose Reductase Inhibitors and Their Content by HPLC Analysis

The study aimed to assess the aldose reductase (AR) inhibition of selected Geranium species and determine the bioactive flavonoid constituents. Flavonoids are known to be good AR inhibitors. Among the species examined, G. sibiricum exhibited potent inhibition of AR (IC50 value, 2.4 µg/mL). Further examination of G. sibiricum, after solvent extraction and fractionation, revealed that the ethyl acetate fraction (IC50 value, 0.41 µg/mL) had a potent AR inhibitory effect. Kaempferol rhamnosides were the active compounds from this fraction. Moreover, G. sibiricum showed the highest content of kaempferol-7-O-rhamnoside and kaempferol-3,7-O-dirhamnoside among the samples examined with a concentration in the extracts of 28.1 and 2.2 mg/g, respectively. This study shows that G. sibiricum exhibits promising AR inhibitory activity, which can be explored further as a natural therapy for treating and managing complications associated with diabetes.

Diabetic Polyneuropathy - Advances in Diagnosis and Intervention Strategies

Over half of people with diabetes mellitus develop diabetic polyneuropathy (DPN), which is a major cause of reduced quality of life due to disabling neuropathic pain, sensory loss, gait instability, fall-related injury, and foot ulceration and amputation. The latter represents a major health and economic burden, with lower limb amputation rates related to diabetes increasing in the UK. There is a need for early diagnosis of DPN so that early management strategies may be instigated, such as achieving tight glucose control and management of cardiovascular risk factors, in an attempt to slow its progression. To this end, a one-stop microvascular assessment involving a combined eye, foot and renal screening clinic has proven feasible in the UK. Unfortunately, there are currently no approved disease-modifying therapies for DPN. Some disease-modifying agents have demonstrated efficacy, but further large trials using appropriate clinical endpoints are required before these treatments can be routinely recommended. There has been emerging evidence highlighting a reduction in vitamin D levels in cases of painful DPN and the potential for vitamin D supplementation in deficient individuals to improve neuropathic pain; however, this needs to be proved in randomised clinical trials. The use of established agents for neuropathic pain in DPN is limited by poor efficacy and adverse effects, but patient stratification using methods such as pain phenotyping are being tested to determine whether this improves the outcomes of such agents in clinical studies. In addition, innovative approaches such as the topical 8% capsaicin patch, new methods of electrical stimulation and novel therapeutic targets such as NaV1.7 offer promise for the future. This article aims to discuss the challenges of diagnosing and managing DPN and to review current and emerging lifestyle interventions and therapeutic options.

Substituted 2-thioxothiazolidin-4-one derivatives showed protective effects against diabetic cataract via inhibition of aldose reductase

In an effort to develop a new class of potent aldose reductase inhibitors against diabetic cataracts, a series of novel 2-thioxothiazolidine-4-one derivatives was synthesized in excellent yields via a facile synthetic route. These compounds were tested against aldehyde (ALR1) and aldose reductase (ALR2) enzymes, where they showed considerable inhibitory activity. Among the tested derivatives, compound 6e showed selective and excellent inhibition of ALR2 over ALR1. The experimental diabetes was induced by the intraperitoneal administration of streptozotocin in male Wistar rats. Compound 6e showed positive modulation of body weight, blood glucose, and blood insulin levels in diabetic rats. Compound 6e also showed ALR2 inhibition as evidenced by Western blot analysis in lens homogenates of Wistar rats having cataract. The docking study of 6e was also performed inside the active site of ALR2 to enumerate the key contacts for inhibitory activity.

Cardiovascular Autonomic Neuropathy and Distal Symmetric Sensorimotor Polyneuropathy: These Two Diabetic Microvascular Complications do not Invariably Co-Exist

Background:

Cardiovascular autonomic neuropathy (CAN) and distal symmetrical sensorimotor polyneuropathy (DSPN) are serious microvascular complications of diabetes mellitus (DM). Their simultaneous development remains disputable. The aim of the present study was to examine the correlation between CAN and the presence/severity of DSPN in DM.

Methods:

Subjects with type 1 (group A: n=51; mean age 40.4 years) and type 2 DM (group B: n=153; mean age 64.6 years) were studied. Evaluation of DSPN was based on neuropathy disability score. Assessment of CAN was based on the battery of 4 standardized cardiovascular autonomic function tests.

Results:

In group A, patients with moderate/severe DSPN exhibited a 12-fold higher likelihood of CAN in univariate analysis (p=0.035). However, significance was lost after adjustment for gender, age, DM duration, and haemoglobin A1c. In group A, likelihood for CAN did not correlate with the presence of mild DSPN in univariate and multivariate analysis. In group B, likelihood of CAN was similar in patients with mild and in those with moderate/severe DSPN compared with patients without DSPN in univariate and multivariate analysis. In between group comparison CAN was similarly distributed in the 2 groups (p for interaction=0.367), in patients with no, mild and moderate/severe DSPN.

Conclusion:

CAN does not always co-exist with degrees of DSPN, ranging from mild to moderate/ severe and is similarly distributed in T1DM and T2DM patients with mild and moderate/severe DSPN and in patients without DSPN.

New N-ribosides and N-mannosides of rhodanine derivatives with anticancer activity on leukemia cell line: Design, synthesis, DFT and molecular modelling studies

N-ribosylation and N-mannosylation compounds have a great role in compounds activity as anticancer. The reaction of 2-thioxo-4-thiazolidinone (rhodanine) derivatives, as aglycon part, was done with ribofuranose and mannopyranose sugars (glycone part) followed by deacetylation without cleavage of the rhodanine under acidic medium. Conformational analysis has been studied using NMR methods (2D, DQF-COSY, HMQC and HMBC). All final the new deprotected nucleosides were screened against leukemia 1210, and were found to be considerably less potent (Ic50% 1.4-10.6 μM) than doxorubicin (Ic50% 0.02 μM). Compounds 10d and 10e which contain ribose moiety have better activity than those with mannose sugar. DFT calculations with B3LYP/6-31 + G (d) level were used to analyze the electronic and geometric characteristics deduced from the stable structure of the compounds. The principal quantum chemical descriptors showed a good correlation with the experimental observations. Rapid Overlay Comparison Similarity (ROCS) study was operated to explain the compounds similarity and to figure out the most important pharmacophoric features.

Astaxanthin inhibits aldose reductase activity in Psammomys obesus, a model of type 2 diabetes and diabetic retinopathy

Astaxanthin (ATX) is a marine carotenoid known for its powerful antioxidant and neuroprotective properties. In this study, we investigated the in vitro and in vivo potential inhibitory effect of ATX on the aldose reductase (AR) activity, a key enzyme in the polyol pathway responsible for the pathogenesis of diabetic complications including diabetic retinopathy (DR). The gerbil Psammomys obesus (P. ob.), an animal model for type 2 diabetes and DR has been used. The erythrocyte and retinal AR activity of P. ob. individuals were, respectively, assessed monthly and at the 7th month during a 7-month hypercaloric diet (HD) using a NADPH oxidation method. Meanwhile, the body weight and blood glucose of the gerbils were monitored. After 7 months, P. ob. individuals were fed with ATX (4.8 mg/kg of body weight) once a day for 1 week. The results showed that the HD-fed animals developed significant obesity and hyperglycemia in comparison with controls. Erythrocyte AR activity showed a progressive and significant increase in the HD-fed group compared with controls. Retinal AR activity was higher in the 7-month HD-fed group compared with controls. Erythrocyte AR activity was markedly decreased after ATX-treatment in vitro and in vivo. These findings suggested that ATX inhibited the erythrocyte AR activity and could be used for DR prevention and/or early treatment.

Repurposing the aldose reductase inhibitor and diabetic neuropathy drug epalrestat for the congenital disorder of glycosylation PMM2-CDG

Phosphomannomutase 2 deficiency, or PMM2-CDG, is the most common congenital disorder of glycosylation and affects over 1000 patients globally. There are no approved drugs that treat the symptoms or root cause of PMM2-CDG. To identify clinically actionable compounds that boost human PMM2 enzyme function, we performed a multispecies drug repurposing screen using a novel worm model of PMM2-CDG, followed by PMM2 enzyme functional studies in PMM2-CDG patient fibroblasts. Drug repurposing candidates from this study, and drug repurposing candidates from a previously published study using yeast models of PMM2-CDG, were tested for their effect on human PMM2 enzyme activity in PMM2-CDG fibroblasts. Of the 20 repurposing candidates discovered in the worm-based phenotypic screen, 12 were plant-based polyphenols. Insights from structure–activity relationships revealed epalrestat, the only antidiabetic aldose reductase inhibitor approved for use in humans, as a first-in-class PMM2 enzyme activator. Epalrestat increased PMM2 enzymatic activity in four PMM2-CDG patient fibroblast lines with genotypes R141H/F119L, R141H/E139K, R141H/N216I and R141H/F183S. PMM2 enzyme activity gains ranged from 30% to 400% over baseline, depending on genotype. Pharmacological inhibition of aldose reductase by epalrestat may shunt glucose from the polyol pathway to glucose-1,6-bisphosphate, which is an endogenous stabilizer and coactivator of PMM2 homodimerization. Epalrestat is a safe, oral and brain penetrant drug that was approved 27 years ago in Japan to treat diabetic neuropathy in geriatric populations. We demonstrate that epalrestat is the first small molecule activator of PMM2 enzyme activity with the potential to treat peripheral neuropathy and correct the underlying enzyme deficiency in a majority of pediatric and adult PMM2-CDG patients.

Editor's choice: Drug repurposing screens using worm and patient fibroblast models of PMM2-CDG led to the discovery of epalrestat, the first activator of PMM2 that targets the root cause of disease.

Understanding the Signaling Pathways Related to the Mechanism and Treatment of Diabetic Peripheral Neuropathy

Worldwide, the most prevalent metabolic disorder is diabetes mellitus (DM), an important condition that has been widely studied. Diabetic peripheral neuropathy (DPN), a complication that can occur with DM, is associated with pain and can result in foot ulcers and even amputation. DPN treatments are limited and mainly focus on pain management. There is a clear need to develop treatments for DPN at all stages. To make this progress, it is necessary to understand the molecular signaling pathways related to DPN. For this review, we aimed to concentrate on the main signaling cascades that contribute to DPN. In addition, we provide information with regard to treatments that are being explored.

Peripheral nerve disease secondary to systemic conditions in children

This review is an overview of systemic conditions that can be associated with peripheral nervous system dysfunction. Children may present with neuropathic symptoms for which, unless considered, a causative systemic condition may not be recognized. Similarly, some systemic conditions may be complicated by comorbid peripheral neuropathies, surveillance for which is indicated. The systemic conditions addressed in this review are critical illness polyneuropathy, chronic renal failure, endocrine disorders such as insulin-dependent diabetes mellitus and multiple endocrine neoplasia type 2b, vitamin deficiency states, malignancies and reticuloses, sickle cell disease, neurofibromatosis, connective tissue disorders, bowel dysmotility and enteropathy, and sarcoidosis. In some disorders presymptomatic screening should be undertaken, while in others there is no benefit from early detection of neuropathy. In children with idiopathic peripheral neuropathies, systemic disorders such as celiac disease should be actively excluded. While management is predominantly focused on symptomatic care through pain control and rehabilitation, some neuropathies improve with effective control of the underlying etiology and in a small proportion a more targeted approach is possible. In conclusion, peripheral neuropathies can be associated with a diverse range of medical conditions and unless actively considered may not be recognized and inadequately managed.

Diabetic neuropathy

The global epidemic of prediabetes and diabetes has led to a corresponding epidemic of complications of these disorders. The most prevalent complication is neuropathy, of which distal symmetric polyneuropathy (for the purpose of this Primer, referred to as diabetic neuropathy) is very common. Diabetic neuropathy is a loss of sensory function beginning distally in the lower extremities that is also characterized by pain and substantial morbidity. Over time, at least 50% of individuals with diabetes develop diabetic neuropathy. Glucose control effectively halts the progression of diabetic neuropathy in patients with type 1 diabetes mellitus, but the effects are more modest in those with type 2 diabetes mellitus. These findings have led to new efforts to understand the aetiology of diabetic neuropathy, along with new 2017 recommendations on approaches to prevent and treat this disorder that are specific for each type of diabetes. In parallel, new guidelines for the treatment of painful diabetic neuropathy using distinct classes of drugs, with an emphasis on avoiding opioid use, have been issued. Although our understanding of the complexities of diabetic neuropathy has substantially evolved over the past decade, the distinct mechanisms underlying neuropathy in type 1 and type 2 diabetes remains unknown. Future discoveries on disease pathogenesis will be crucial to successfully address all aspects of diabetic neuropathy, from prevention to treatment.

Diabetic neuropathy

The global epidemic of prediabetes and diabetes has led to a corresponding epidemic of complications of these disorders. The most prevalent complication is neuropathy, of which distal symmetric polyneuropathy (for the purpose of this Primer, referred to as diabetic neuropathy) is very common. Diabetic neuropathy is a loss of sensory function beginning distally in the lower extremities that is also characterized by pain and substantial morbidity. Over time, at least 50% of individuals with diabetes develop diabetic neuropathy. Glucose control effectively halts the progression of diabetic neuropathy in patients with type 1 diabetes mellitus, but the effects are more modest in those with type 2 diabetes mellitus. These findings have led to new efforts to understand the aetiology of diabetic neuropathy, along with new 2017 recommendations on approaches to prevent and treat this disorder that are specific for each type of diabetes. In parallel, new guidelines for the treatment of painful diabetic neuropathy using distinct classes of drugs, with an emphasis on avoiding opioid use, have been issued. Although our understanding of the complexities of diabetic neuropathy has substantially evolved over the past decade, the distinct mechanisms underlying neuropathy in type 1 and type 2 diabetes remains unknown. Future discoveries on disease pathogenesis will be crucial to successfully address all aspects of diabetic neuropathy, from prevention to treatment.

Aldose reductase inhibitor ranirestat significantly improves nerve conduction velocity in diabetic polyneuropathy: A randomized double-blind placebo-controlled study in Japan

AIMS/INTRODUCTION

Diabetic polyneuropathy is one of the most frequent diabetic complications, and impairs patients' quality of life. We evaluated the efficacy and safety of ranirestat (40 mg/day) in patients with diabetic polyneuropathy.

MATERIALS AND METHODS

This was a multicenter, placebo-controlled, randomized double-blind, parallel-group, phase III study in which 557 patients were randomly assigned to either the ranirestat or placebo group and assessed for 52 weeks. The co-primary end-points were the changes in tibial motor nerve conduction velocity and total modified Toronto Clinical Neuropathy Score as a measure of clinical symptoms.

RESULTS

There was a significant increase in tibial motor nerve conduction velocity in the ranirestat group compared with the placebo group. The difference between groups in the change at last observation was 0.52 m/s (P = 0.021). Increases in nerve conduction velocity in the ranirestat group were found not only in the tibial motor nerves, but also in the median motor nerves, proximal median sensory nerves and distal median sensory nerves. No significant differences in modified Toronto Clinical Neuropathy Score or safety parameters were found between the two groups.

CONCLUSIONS

Ranirestat (40 mg/day) was well tolerated and improved nerve conduction velocity. Regarding symptoms and signs, no detectable benefits over the placebo were observed in the ranirestat group during the 52 weeks of treatment.

A non-invasive, multi-target approach to treat diabetic retinopathy

Hyperglycemia invoke number of pathways resulting in development of diabetic retinopathy (DR), including protein kinase C activation, increased expression of VEGF, advanced glycation end product (AGEs) formation and activation of polyol pathway, among which the pathophysiology of aldose reductase (ALR2) of the polyol pathway is evident by more than a decade of research. Subtle involvement of ALR2 in invoking various pathways of diabetic complications has caused an increase in attention towards the identification of novel aldose reductase inhibitors (ARIs). Numerous ARIs of different classes were employed in the treatment of diabetic complications initially, but few came into light as drugs. Though no ALR2 inhibitor has been used for the treatment or control of DR, Epalrestat has been used worldwide for treating diabetic neuropathy. This review critically analyses different treatments available for diabetic retinopathy, their limitations and the importance of the development of novel inhibitors of ALR2 that could prevent progression of DR, by causing a direct or indirect effect on controlling factors associated with DR.

Diabetic neuropathy and the sensory neuron: New aspects of pathogenesis and their treatment implications

Diabetic polyneuropathy (DPN) continues to be generally considered as a "microvascular" complication of diabetes mellitus alongside nephropathy and retinopathy. The microvascular hypothesis, however, might be tempered by the concept that diabetes directly targets dorsal root ganglion sensory neurons. This neuron-specific concept, supported by accumulating evidence, might account for important features of DPN, such as its early sensory neuron degeneration. Diabetic sensory neurons develop neuronal atrophy alongside a series of messenger ribonucleic acid (RNA) changes related to declines in structural proteins, increases in heat shock protein, increases in the receptor for advanced glycation end-products, declines in growth factor signaling and other changes. Insulin is recognized as a potent neurotrophic factor, and insulin ligation enhances neurite outgrowth through activation of the phosphoinositide 3-kinase-protein kinase B pathway within sensory neurons and attenuates phenotypic features of experimental DPN. Several interventions, including glucagon-like peptide-1 agonism, and phosphatase and tensin homolog inhibition to activate growth signals in sensory neurons, or heat shock protein overexpression, prevent or reverse neuropathic abnormalities in experimental DPN. Diabetic sensory neurons show a unique pattern of microRNA alterations, a key element of messenger RNA silencing. For example, let-7i is widely expressed in sensory neurons, supports their growth and is depleted in experimental DPN; its replenishment improves features of DPN models. Finally, impairment of pre-messenger RNA splicing in diabetic sensory neurons including abnormal nuclear RNA metabolism and structure with loss of survival motor neuron protein, a neuron survival molecule, and overexpression of CWC22, a splicing factor, offer further novel insights. The present review addresses these new aspects of DPN sensory neurodegeneration.

Fluoxetine pretreatment enhances neurogenic, angiogenic and immunomodulatory effects of MSCs on experimentally induced diabetic neuropathy

Being one of the most debilitating complications among diabetic patients, diabetic polyneuropathy (DPN) is a paramount point of continuous research. Stem cell therapies have shown promising results. However, limited cell survival and paracrine activities hinder its transfer from bench to bedside. We designed this study to evaluate fluoxetine-pretreatment technique of mesenchymal stem cells (MSCs) as an approach to enhance their paracrine and immunomodulatory properties in DPN. Effects of fluoxetine treatment of MSCs were tested in vitro. Forty-two adult Wistar male albino rats were utilized, further subdivided into control, diabetic, MSC-treated and fluoxetine-pretreated MSC groups. Sciatic nerve sections were prepared for light and electron microscope examination and immunohistochemical detection of neurofilament (NF) protein. Also, we assessed in vitro survival and paracrine properties of fluoxetine-pretreated MSCs. Real time PCR of BDNF, VEGF, IL-1β, and IL-10 expression in tissue homogenate was performed. Our results showed restoration of normal neuronal histomorphology and ultrastructure, moreover, immunohistochemical expression of anti-neurofilament protein was significantly elevated in MSC-treated groups compared to the diabetic one. Fluoxetine enhanced the MSC survival and their paracrine properties of MSCs in vitro. Furthermore, the fluoxetine-pretreated MSC group revealed a significant elevation of mRNA expression of BDNF (neurotrophic factor) and VEGF (angiogenic factor), denoting ameliorated MSC paracrine properties. Similarly, improved immunomodulatory functions were evident by a significant reduction of interleukin-1β mRNA expression (pro-inflammatory) and a reciprocal significant increase of interleukin-10 (anti-inflammatory). We concluded that fluoxetine-pretreatment of MSCs boosts their survival, paracrine, and immunomodulatory traits and directly influenced neuronal histomorphology. Hence, it presents a promising intervention of diabetic polyneuropathy. Graphical Abstract.

Expression levels of aldose reductase enzyme, vascular endothelial growth factor, and intercellular adhesion molecule-1 in the anterior lens capsule of diabetic cataract patients

PURPOSE

To compare the levels of aldose reductase (ALR) enzyme, intercellular adhesion molecule-1 (ICAM-1), and vascular endothelial growth factor (VEGF) in the anterior lens capsule of diabetic versus nondiabetic patients.

SETTING

Alexandria Main University Hospital, Alexandria, Egypt.

DESIGN

Prospective case-control study.

METHODS

The study enrolled patients undergoing cataract extraction and divided them into 3 groups: eyes that had proliferative diabetic retinopathy (PDR), eyes that had nonproliferative diabetic retinopathy (NPDR), and nondiabetic eyes. The anterior lens capsules were obtained by performing femtosecond laser-assisted capsulorhexis. Concentrations of ALR, ICAM-1, and VEGF in the lens capsule specimens were measured using human enzyme-linked immunosorbent assay.

RESULTS

This study comprised 200 patients (200 eyes); 51 eyes had PDR, 49 eyes had NPDR, and 100 eyes were nondiabetic. The mean ALR, ICAM-1, and VEGF levels in the anterior capsule of diabetic group were 2.84 nanogram (ng)/mL ± 0.51 (SD), 87.73 ± 22.84 picogram (pg)/mL, and 75.53 ± 14.95 pg/mL, respectively; whereas, in the nondiabetic group, they were 1.44 ± 0.17 ng/mL, 35.45 ± 2.8 pg/mL, and 33.55 ± 5.47 pg/mL, respectively. In comparing the concentrations of these mediators, both the PDR and NPDR groups had significantly higher levels compared with the nondiabetic eyes (P < .001). In addition, eyes with PDR had significantly higher levels of these mediators than eyes with NPDR (P < .001).

CONCLUSION

The concentrations of ALR, ICAM-1, and VEGF in the anterior lens capsule of diabetic patients are significantly higher than those of nondiabetics. A significantly higher level of 3 mediators in eyes with PDR compared with those with NPDR might allow the use of them as a biomarker for severity of diabetic retinopathy.

Epalrestat, an Aldose Reductase Inhibitor, Restores Erectile Function in Streptozocin-induced Diabetic Rats

Epalrestat, an aldose reductase inhibitor (ARI), was adopted to improve the function of peripheral nerves in diabetic patients. The aim of this study was to investigate whether epalrestat could restore the erectile function of diabetic erectile dysfunction using a rat model. From June 2016, 24 rats were given streptozocin (STZ) to induce the diabetic rat model, and epalrestat was administered to ten diabetic erectile dysfunction (DED) rats. Intracavernous pressure (ICP) and mean systemic arterial pressure (MAP), levels of aldose reductase (AR), nerve growth factor (NGF), neuronal nitric oxide synthase (nNOS), α-smooth muscle antigen (α-SMA), and von Willebrand factor (vWF) in the corpus cavernosum were analyzed. We discovered that epalrestat acted on cavernous tissue and partly restored erectile function. NGF and nNOS levels in the corpora were increased after treatment with epalrestat. We also found that the content of α-SMA-positive smooth muscle cells and vWF-positive endothelial cells in the corpora cavernosum were declined. Accordingly, epalrestat might improve erectile function by increasing the upregulation of NGF and nNOS to restore the function of the dorsal nerve of the penis.

Alpha lipoic acid combined with epalrestat: a therapeutic option for patients with diabetic peripheral neuropathy

Background

Alpha lipoic acid (ALA), a type of antioxidant, is used in combination with epalrestat in the treatment of diabetic peripheral neuropathy (DPN). However, whether combined treatment is superior to epalrestat monotherapy is controversial.

Methods

We conducted a systematic search of PubMed, Cochrane Library and Chinese databases to identify all randomized controlled trials (RCTs) up to October 31, 2017. Data were extracted to evaluate methodological quality and analyzed using Review Manager 5.3.0 software.

Results

Twelve studies were included. Compared to epalrestat monotherapy, ALA 600 mg/d once a day (qd) combined with epalrestat 50 mg three times a day (tid) augmented the total effectiveness rate (14 days – risk ratio [RR]: 1.40, 95% CI: 1.16–1.69, P=0.0005; 28 days – RR: 1.48, 95% CI: 1.27–1.72, P<0.00001); at the same, it could improve the median motor nerve conduction velocity (MNCV) and sensory nerve conduction velocity (SNCV), peroneal MNCV, and SNCV after 14, 21, and 28 days of treatment and could reduce the Toronto Clinical Scoring System (TCSS) (weighted mean difference [WMD]: −1.60, 95% CI: (−2.91, −0.29), P=0.02) and Total Symptom Score (TSS) (WMD: −0.93, 95% CI: −1.27, −0.60, P<0.00001) after 21 days of treatment. The treatment strategy of ALA 300 mg/d qd combined with epalrestat 50 mg tid had the same effects in regard to the total effectiveness rate (RR: 1.37, 95% CI: 1.18–1.59, P<0.0001), median MNCV (WMD: 6.12, 95% CI: 5.04, 7.20, P=0.00001), median SNCV (WMD: 6.70, 95% CI: 5.75, 7.65, P=0.00001), peroneal MNCV (WMD: 6.68, 95% CI: 5.82, 7.55, P=0.00001), and peroneal SNCV (WMD: 4.27, 95% CI: 3.34, 5.20, P=0.00001) after 28 days of treatment.

Conclusion

ALA combined with epalrestat is an effective option for DPN patients. Future large-sample RCTs should be conducted to further confirm this finding.

Pharmacologic targeting of the diabetic stem cell mobilopathy

Diabetes is a chronic metabolic disease characterized by hyperglycemia and several associated biochemical abnormalities. Diabetes leads to multiorgan complications that collectively reduce life expectancy. Hematopoietic stem cells (HSCs) are nested within bone marrow (BM) niches whence they can be mobilized to the peripheral circulation. Clinically, this is done for HSC collection and autologous or allogenic transplantation. A great amount of data from basic and clinical studies support that diabetic patients are poor HSC mobilizers owing to BM remodeling. Dysfunction of the BM shares pathophysiological features and pathways with typical chronic diabetic complications that affect other issues (e.g. the retina and the kidney). From a clinical perspective, impaired HSC mobilization translates into the failure to collect a minimum number of CD34⁺ cells to achieve a safe engraftment after transplantation. Furthermore, blunted mobilization is associated with reduced steady-state levels of circulating HSCs, which have been consistently described in diabetic patients and associated with increased risk of adverse outcomes, including cardiovascular events and death. In this review, we discuss the most clinically relevant pharmacological options to overcome impaired HSC mobilization in diabetes. These therapeutic strategies may result in an improved outcome of diabetic patients undergoing HSC transplantation and restore circulating HSC levels, thereby protecting from adverse cardiovascular outcomes.

Metabolic Syndrome and Neuroprotection

Introduction: Over the years the prevalence of metabolic syndrome (MetS) has drastically increased in developing countries as a major byproduct of industrialization. Many factors, such as the consumption of high-calorie diets and a sedentary lifestyle, bolster the spread of this disorder. Undoubtedly, the massive and still increasing incidence of MetS places this epidemic as an important public health issue. Hereon we revisit another outlook of MetS beyond its classical association with cardiovascular disease (CVD) and Diabetes Mellitus Type 2 (DM2), for MetS also poses a risk factor for the nervous tissue and threatens neuronal function. First, we revise a few essential concepts of MetS pathophysiology. Second, we explore some neuroprotective approaches in MetS pertaining brain hypoxia. The articles chosen for this review range from the years 1989 until 2017; the selection criteria was based on those providing data and exploratory information on MetS as well as those that studied innovative therapeutic approaches.

Pathophysiology: The characteristically impaired metabolic pathways of MetS lead to hyperglycemia, insulin resistance (IR), inflammation, and hypoxia, all closely associated with an overall pro-oxidative status. Oxidative stress is well-known to cause the wreckage of cellular structures and tissue architecture. Alteration of the redox homeostasis and oxidative stress alter the macromolecular array of DNA, lipids, and proteins, in turn disrupting the biochemical pathways necessary for normal cell function.

Neuroprotection: Different neuroprotective strategies are discussed involving lifestyle changes, medication aimed to mitigate MetS cardinal symptoms, and treatments targeted toward reducing oxidative stress. It is well-known that the routine practice of physical exercise, aerobic activity in particular, and a complete and well-balanced nutrition are key factors to prevent MetS. Nevertheless, pharmacological control of MetS as a whole and pertaining hypertension, dyslipidemia, and endothelial injury contribute to neuronal health improvement.

Conclusion: The development of MetS has risen as a risk factor for neurological disorders. The therapeutic strategies include multidisciplinary approaches directed to address different pathological pathways all in concert.

Administration of daily 5 mg tadalafil improves endothelial function in patients with benign prostatic hyperplasia

INTRODUCTION

Tadalafil is a promising phosphodiesterase (PDE) 5 inhibitor prescribed for erectile dysfunction (ED). Daily low dose (5 mg) of tadalafil has also been used for the treatment of male lower urinary tract symptoms (LUTS) associated with benign prostate hyperplasia (BPH). PDE5 inhibitors induce relaxation of smooth muscle cells in the urethra, prostate, bladder neck, and blood vessels. The aim of this study was to investigate the efficacy of tadalafil on vessels endothelial function, in patients with male LUTS symptoms associated with BPH.

METHODS

The Institutional Review Board (IRB) approved this clinical study and informed consents had been obtained from 81 BPH patients. The following male LUTS parameters: international prostate symptom score (IPSS), overactive bladder symptom score (OABSS), voiding volume, max and mean voiding flow on voiding flowmetry examination and post-voiding residual urine (RU) were compared at 0, 1, 3, 6, and 12 months after a daily dose of 5 mg tadalafil. In addition, erectile function was evaluated by the sexual health inventory for men (SHIM) score and vessels endothelial function and peripheral neuropathy were assessed by the brachial-ankle pulse wave velocity (baPWV), ankle brachial index (ABI), and vibration perception threshold (VPT) at 0, 3, 6, and 12 months after treatment.

RESULTS

The mean age of 81 patients was 66.4 ± 11.4 years old. Their prostate size was 30.2 ± 22.1 ml. Male LUTS parameters including IPSS, OABSS, and RU showed significant improvement from 1 to 12 months after tadalafil administration. Max and mean voiding flow was significantly increased at 6 months after tadalafil treatment. The SHIM score showed significant improvement after 3 months. Whilst, the results of baPWV also showed significant improvement from 3 to 12 months. ABI was also significantly improved at 6 months. However, there was no change in the VPT at any time point.

CONCLUSIONS

Tadalafil is effective for both male LUTS and ED. It is also shown that tadalafil improves baPWV, which we can conclude that higher vessels elasticity has been obtained. This major finding of this study shows that tadalafil has the potency to improve vessels endothelial dysfunction in patients with BPH.

Cardiac autonomic neuropathy: Risk factors, diagnosis and treatment

Cardiac autonomic neuropathy (CAN) is a serious complication of diabetes mellitus (DM) that is strongly associated with approximately five-fold increased risk of cardiovascular mortality. CAN manifests in a spectrum of things, ranging from resting tachycardia and fixed heart rate (HR) to development of "silent" myocardial infarction. Clinical correlates or risk markers for CAN are age, DM duration, glycemic control, hypertension, and dyslipidemia (DLP), development of other microvascular complications. Established risk factors for CAN are poor glycemic control in type 1 DM and a combination of hypertension, DLP, obesity, and unsatisfactory glycemic control in type 2 DM. Symptomatic manifestations of CAN include sinus tachycardia, exercise intolerance, orthostatic hypotension (OH), abnormal blood pressure (BP) regulation, dizziness, presyncope and syncope, intraoperative cardiovascular instability, asymptomatic myocardial ischemia and infarction. Methods of CAN assessment in clinical practice include assessment of symptoms and signs, cardiovascular reflex tests based on HR and BP, short-term electrocardiography (ECG), QT interval prolongation, HR variability (24 h, classic 24 h Holter ECG), ambulatory BP monitoring, HR turbulence, baroreflex sensitivity, muscle sympathetic nerve activity, catecholamine assessment and cardiovascular sympathetic tests, heart sympathetic imaging. Although it is common complication, the significance of CAN has not been fully appreciated and there are no unified treatment algorithms for today. Treatment is based on early diagnosis, life style changes, optimization of glycemic control and management of cardiovascular risk factors. Pathogenetic treatment of CAN includes: Balanced diet and physical activity; optimization of glycemic control; treatment of DLP; antioxidants, first of all α-lipoic acid (ALA), aldose reductase inhibitors, acetyl-L-carnitine; vitamins, first of all fat-soluble vitamin B1; correction of vascular endothelial dysfunction; prevention and treatment of thrombosis; in severe cases-treatment of OH. The promising methods include prescription of prostacyclin analogues, thromboxane A2 blockers and drugs that contribute into strengthening and/or normalization of Na+, K+-ATPase (phosphodiesterase inhibitor), ALA, dihomo-γ-linolenic acid (DGLA), ω-3 polyunsaturated fatty acids (ω-3 PUFAs), and the simultaneous prescription of ALA, ω-3 PUFAs and DGLA, but the future investigations are needed. Development of OH is associated with severe or advanced CAN and prescription of nonpharmacological and pharmacological, in the foreground midodrine and fludrocortisone acetate, treatment methods are necessary.

Aldo-Keto Reductases: Multifunctional Proteins as Therapeutic Targets in Diabetes and Inflammatory Disease

Aldose reductase (AR) is an NADPH-dependent aldo-keto reductase that has been shown to be involved in the pathogenesis of several blinding diseases such as uveitis, diabetic retinopathy (DR) and cataract. However, possible mechanisms linking the action of AR to these diseases are not well understood. As DR and cataract are among the leading causes of blindness in the world, there is an urgent need to explore therapeutic strategies to prevent or delay their onset. Studies with AR inhibitors and gene-targeted mice have demonstrated that the action of AR is also linked to cancer onset and progression. In this review we examine possible mechanisms that relate AR to molecular signaling cascades and thus explain why AR inhibition is an effective strategy against colon cancer as well as diseases of the eye such as uveitis, cataract, and retinopathy.

Efficacy of epalrestat plus α-lipoic acid combination therapy versus monotherapy in patients with diabetic peripheral neuropathy: a meta-analysis of 20 randomized controlled trials

Objective

To evaluate the efficacy of α-lipoic acid (ALA) plus epalrestat combination therapy in the treatment of diabetic peripheral neuropathy (DPN).

Data Sources

The electronic databases of PubMed, Medline, Embase, the Cochrane Library, the Chinese National Knowledge Infrastructure, the Wanfang Database and the Chinese Biomedical Database were used to retrieve relevant studies without language restrictions. The search was conducted from the inception of each database to 7 October 2016. The key terms were (diabetic peripheral neuropathy or diabetic neuropathy or DPN) AND (α-lipoic acid or lipoic acid or thioctic acid) AND epalrestat.

Data Selection

All of the eligible studies met the following inclusion criteria: (1) Randomized controlled trials that compared efficacy and safety of epalrestat plus ALA combination therapy versus epalrestat or ALA monotherapy in patients with DPN. (2) The minimum duration of treatment was 2 weeks. (3) The DPN patients were diagnosed using the World Health Organization standardized type 2 diabetes mellitus and DPN criteria. (4) Studies contained at least one measure that could reflect the efficacy of the drug and nerve conduction velocities. Studies in which the control group used epalrestat or ALA combined with other drugs were excluded. Statistical analyses were performed using STATA software for meta-analysis.

Outcome Measures

The primary outcomes were the therapeutic efficacy, median motor nerve conduction velocity (MNCV), median sensory nerve conduction velocity (SNCV), peroneal MNCV and peroneal SNCV.

Results

Twenty studies with 1894 DPN patients were included, including 864 patients in the ALA plus epalrestat group, 473 in the ALA group and 557 in the epalrestat group. The efficacy of ALA plus epalrestat combination therapy was superior to ALA and epalrestat monotherapies (RR = 1.29, 95% CI: 1.21-1.38; RR = 1.43, 95% CI: 1.34-1.54, respectively). ALA plus epalrestat combination therapy also significantly improved median MNCV (WMD = 5.41, 95% CI: 2.07-8.75), median SNCV (WMD = 5.87, 95% CI: 1.52-10.22), peroneal MNCV (WMD = 5.59, 95% CI: 2.70-8.47) and peroneal SNCV (WMD = 4.57, 95% CI: 2.46-6.68).

Conclusion

: ALA plus epalrestat combination therapy was superior to ALA and epalrestat monotherapies for clinical efficacy and nerve conduction velocities in patients with DPN.