Aldose reductase inhibitor fidarestat attenuates leukocyte-endothelial interactions in experimental diabetic rat retina in vivo

Aldose Reductase as a Key Target in the Prevention and Treatment of Diabetic Retinopathy: A Comprehensive Review

The escalating global prevalence of diabetes mellitus (DM) over the past two decades has led to a persistent high incidence of diabetic retinopathy (DR), necessitating screening for early symptoms and proper treatment. Effective management of DR aims to decrease vision impairment by controlling modifiable risk factors including hypertension, obesity, and dyslipidemia. Moreover, systemic medications and plant-based therapy show promise in advancing DR treatment. One of the key mechanisms related to DR pathogenesis is the polyol pathway, through which aldose reductase (AR) catalyzes the conversion of glucose to sorbitol within various tissues, including the retina, lens, ciliary body and iris. Elevated glucose levels activate AR, leading to osmotic stress, advanced glycation end-product formation, and oxidative damage. This further implies chronic inflammation, vascular permeability, and angiogenesis. Our comprehensive narrative review describes the therapeutic potential of aldose reductase inhibitors in treating DR, where both synthetic and natural inhibitors have been studied in recent decades. Our synthesis aims to guide future research and clinical interventions in DR management.

Moderating Gut Microbiome/Mitochondrial Axis in Oxazolone Induced Ulcerative Colitis: The Evolving Role of β-Glucan and/or, Aldose Reductase Inhibitor, Fidarestat

A mechanistic understanding of the dynamic interactions between the mitochondria and the gut microbiome is thought to offer innovative explanations for many diseases and thus provide innovative management approaches, especially in GIT-related autoimmune diseases, such as ulcerative colitis (UC). β-Glucans, important components of many nutritious diets, including oats and mushrooms, have been shown to exhibit a variety of biological anti-inflammatory and immune-modulating actions. Our research study sought to provide insight into the function of β-glucan and/or fidarestat in modifying the microbiome/mitochondrial gut axis in the treatment of UC. A total of 50 Wistar albino male rats were grouped into five groups: control, UC, β-Glucan, Fidarestat, and combined treatment groups. All the groups were tested for the presence of free fatty acid receptors 2 and 3 (FFAR-2 and -3) and mitochondrial transcription factor A (TFAM) mRNA gene expressions. The reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and ATP content were found. The trimethylamine N-oxide (TMAO) and short-chain fatty acid (SCFA) levels were also examined. Nuclear factor kappa β (NF-kβ), nuclear factor (erythroid-2)-related factor 2 (Nrf2) DNA binding activity, and peroxisome proliferator-activated receptor gamma co-activator-1 (PGC-1) were identified using the ELISA method. We observed a substantial increase FFAR-2, -3, and TFAM mRNA expression after the therapy. Similar increases were seen in the ATP levels, MMP, SCFA, PGC-1, and Nrf2 DNA binding activity. The levels of ROS, TMAO, and NF-kβ, on the other hand, significantly decreased. Using β-glucan and fidarestat together had unique therapeutic benefits in treating UC by focusing on the microbiota/mitochondrial axis, opening up a new avenue for a potential treatment for such a complex, multidimensional illness.

Potential effect of tropical fruits Phyllanthus emblica L. for the prevention and management of type 2 diabetic complications: a systematic review of recent advances

Phyllanthus emblica is a fruit widely consumed in subtropical areas, which is rich in polyphenols and other nutrients. There are increasing evidences that as a daily and nutritious fruit, it may have a positive role in controlling diabetic complications. According to the new study, its mechanisms include enhancing the functioning of insulin, reducing insulin resistance, activating the insulin-signaling pathway, protecting β-cells, scavenging free radicals, alleviating inflammatory reactions, and reducing the accumulation of advanced glycation end products. Owing to its few side effects, and low price, it should be easily accepted by patients and has potential for preventing diabetes. Taken together, Phyllanthus emblica may be an ideal fruit for controlling diabetic complications. This review highlights the latest findings of the role of Phyllanthus emblica in anti-diabetes and its complications, especially clarifies the molecular mechanism of the chemical components related to this effect, and prospects some existing problems and future research directions.

Reactive oxygen species: sources, consequences and targeted therapy in type 2 diabetes

Oxidative stress has been considered as a central mediator in the progression of diabetic complication. The intracellular reactive oxygen species (ROS) leads to oxidative stress and it is raised from the mitochondria as well as by activation of five major pathways: increased polyol pathway flux, activation of protein kinase C (PKC) pathway, increased formation of advanced glycation end products (AGEs), over activity of hexosamine pathway and increased production of angiotensin II. The increased ROS through these pathways leads to β-cell dysfunction and insulin resistance, responsible for cell damage and death. This review not only highlights the sources of ROS production and their involvement in the progression of diabetes, but also emphasizes on pharmacological interventions and targeting of ROS in type 2 diabetes. This review summarizes the ROS as potential therapeutic targets, based on a putative mechanism in the progression of the diabetes. It also summarizes current knowledge of ROS activation in type 2 diabetes as well as ROS as a possible target for its treatment. Eventually, it would be a promising target for various strategies and drugs to modulate ROS levels in diabetes.

A combination of the main constituents of Fufang Xueshuantong Capsules shows protective effects against streptozotocin-induced retinal lesions in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Fufang Xueshuantong Capsule, an herbal formula licensed for clinical use in China, which is composed of Panax notoginseng (Burkill) F.H. Chen, Salvia miltiorrhiza Bunge, Astragalus membranaceus (Fisch.) Bunge, and Scrophularia ningpoensis Hemsl, has proven effective for the treatment of diabetic retinopathy. However, its bioactive constituents are still ambiguous. In this study, the therapeutic effects of a combination of the main constituents of Fufang Xueshuantong Capsule (cFXT) were evaluated in streptozotocin (STZ)-induced retinal lesions to identify the bioactive constituents.

METHODS

Sprague-Dawley rats, except for those in the control group (vehicle+vehicle), were administered a single injection of 60mg/kg STZ. One-week later, STZ-treated rats were randomly divided into three groups-one STZ group (STZ+vehicle) and two cFXT treatment groups (STZ+cFXT). The rats in the latter two groups received cFXT 44.8mg/kg or cFXT 22.4mg/kg by intragastric gavage once per day, for 24 consecutive weeks. The rats in the control and STZ groups received the vehicle in the same way. Body weights and fasting blood glucose levels were recorded every four weeks. After treatment, hemorheological tests were performed to record the erythrocyte aggregation indexes, blood viscosity, and plasma viscosity. The trypsin digestion method was used to observe pericyte and acellular capillary counts in the retina. Ultraviolet spectrophotometry was utilized to measure the activity of aldose reductase (AR) by measuring the nicotinamide adenine dinucleotide phosphate (NADPH) consumption at 340nm. An immunohistochemical assay was used to observe the expressions of vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF) in the retina. The expression levels of intercellular adhesion molecule-1 (ICAM-1), endothelin-1 (RT-1),and occludin in the retina were tested by the western blot assay.

RESULTS

cFXT is composed of 991.44mg/g saponins of Panax notoginseng, 1.62mg/g harpagoside, 0.70mg/g cryptotanshinone, 0.74mg/g tanshinone I, and 5.50mg/g astragaloside A. Although it showed no effects on the increased body weight and blood glucose levels induced by STZ in rats. However, it showed a tendency to attenuate the increase in erythrocyte aggregation, plasma viscosity, and acellular vessel and pericyte loss, paralleled with a reversal of the hyper-activation of AR, the hyper-expression of VEGF, ICAM-1, and ET-1, and the hypo-expression of PEDF and occludin in the retinas of STZ-treated rats.

CONCLUSION

The saponins of Panax notoginseng, harpagoside, cryptotanshinone, tanshinone I, and astragaloside A are the main bioactive constituents of Fufang Xueshuantong Capsule and contribute to the attenuation of STZ-induced retinal lesions in rats. These constituents can be used as the base to optimize a new drug for the treatment of diabetic retinopathy, and can be selected for quality control of Fufang Xueshuantong Capsules.

Novel pharmacotherapies in diabetic retinopathy

This is a summary of current and emerging pharmacologic therapies utilized in the treatment of diabetic retinopathy (DR). Current therapies, such as ranibizumab, bevacizumab, triamcinolone acetonide, and fluocinolone acetonide, inhibit angiogenesis and inflammation and may be used alone or in combination with laser treatment. Emerging therapies aim to reduce oxidative stress or inhibit other signal transduction pathways, including the protein kinase C cascade and aldose reductase pathway. Future therapies may target other molecules crucial to the pathogenesis of DR, including hepatocyte growth factors and matrix metalloproteinase 9. Finally, the emergence of novel mechanisms of medication delivery may also be on the horizon.

Tonicity response element binding protein associated with neuronal cell death in the experimental diabetic retinopathy

AIM

To study the contribution of tonicity response element binding protein (TonEBP) in retinal ganglion cell (RGC) death of diabetic retinopathy (DR).

METHODS

Diabetes was induced in C57BL/6 mice by five consecutive intraperitoneal injections of 55 mg/kg streptozotocin (STZ). Control mice received vehicle (phosphate-buffered saline). All mice were killed 2mo after injections, and the extent of cell death and the protein expression levels of TonEBP and aldose reductase (AR) were examined.

RESULTS

The TonEBP and AR protein levels and the death of RGC were significantly increased in the retinas of diabetic mice compared with controls 2mo after the induction of diabetes. Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL)-positive signals co-localized with TonEBP immunoreactive RGC. These changes were increased in the diabetic retinas compared with controls.

CONCLUSION

The present data show that AR and TonEBP are upregulated in the DR and TonEBP may contribute to apoptosis of RGC in the DR.

Inhibition of ocular aldose reductase by a new benzofuroxane derivative ameliorates rat endotoxic uveitis

The study investigated the effects of the aldose reductase (AR) inhibitor benzofuroxane derivative 5(6)-(benzo[d]thiazol-2-ylmethoxy) benzofuroxane (herein referred to as BF-5m) on the biochemical and tissue alterations induced by endotoxic uveitis in rats. BF-5m has been administered directly into the vitreous, in order to assess the expression and levels of (i) inflammatory markers such as the ocular ubiquitin-proteasome system, NF-κB, TNF-α, and MCP-1; (ii) prooxidant and antioxidant markers such as nitrotyrosine, manganese superoxide dismutase (MnSOD), and glutathione peroxidase (GPX); (iii) apoptotic/antiapoptotic factors caspases and Bcl-xl; (iv) markers of endothelial progenitor cells (EPCs) recruitment such as CD34 and CD117. 5 μL of BF-5m (0.01; 0.05; and 0.1 μM) into the right eye decreased in a dose-dependent manner the LPS-induced inflammation of the eye, reporting a clinical score 1. It reduced the ocular levels of ubiquitin, 20S and 26S proteasome subunits, NF-κB subunits, TNF-α, MCP-1, and nitrotyrosine. BF-5m ameliorated LPS-induced decrease in levels of MnSOD and GPX. Antiapoptotic effects were seen from BF-5m by monitoring the expression of Bcl-xl, an antiapoptotic protein. Similarly, BF-5m increased recruitment of the EPCs within the eye, as evidenced by CD34 and CD117 antibodies.

Molecular mechanisms of diabetic retinopathy, general preventive strategies, and novel therapeutic targets

The growing number of people with diabetes worldwide suggests that diabetic retinopathy (DR) and diabetic macular edema (DME) will continue to be sight threatening factors. The pathogenesis of diabetic retinopathy is a widespread cause of visual impairment in the world and a range of hyperglycemia-linked pathways have been implicated in the initiation and progression of this condition. Despite understanding the polyol pathway flux, activation of protein kinase C (KPC) isoforms, increased hexosamine pathway flux, and increased advanced glycation end-product (AGE) formation, pathogenic mechanisms underlying diabetes induced vision loss are not fully understood. The purpose of this paper is to review molecular mechanisms that regulate cell survival and apoptosis of retinal cells and discuss new and exciting therapeutic targets with comparison to the old and inefficient preventive strategies. This review highlights the recent advancements in understanding hyperglycemia-induced biochemical and molecular alterations, systemic metabolic factors, and aberrant activation of signaling cascades that ultimately lead to activation of a number of transcription factors causing functional and structural damage to retinal cells. It also reviews the established interventions and emerging molecular targets to avert diabetic retinopathy and its associated risk factors.

Novel transgenic mouse models develop retinal changes associated with early diabetic retinopathy similar to those observed in rats with diabetes mellitus

Retinal capillary pericyte degeneration has been linked to aldose reductase (AR) activity in diabetic retinopathy (DR). Since the development of DR in mice and rats has been reported to differ and that this may be linked to differences in retinal sorbitol levels, we have established new murine models of early onset diabetes mellitus as tools for investigating the role of AR in DR. Transgenic diabetic mouse models were developed by crossbreeding diabetic C57BL/6-Ins2(Akita)/J (AK) with transgenic C57BL mice expressing green fluorescent protein (GFP), human aldose reductase (hAR) or both in vascular tissues containing smooth muscle actin-α (SMAA). Changes in retinal sorbitol levels were determined by HPLC while changes of growth factors and signaling were investigated by Western Blots. Retinal vascular changes were quantitatively analyzed on elastase-digestion flat mounts. Results show that sorbitol levels were higher in neural retinas of diabetic AK-SMAA-GFP-hAR compared to AK-SMAA-GFP mice. AK-SMAA-GFP-hAR mice showed induction of the retinal growth factors VEGF, IGF-1, bFGF and TGFβ, as well as signaling changes in P-Akt, P-SAPK/JNK, and P-44/42 MAPK. Increased loss of nuclei per capillary length and a significant increase in the percentage of acellular capillaries presented in 18 week old AK-SMAA-GFP-hAR mice. These changes are similar to those observed in streptozotocin-induced diabetic rats. Retinal changes in both mice and rats were prevented by inhibition of AR. These studies confirm that the increased expression of AR in mice results in the development of retinal changes associated with the early stages of DR that are similar to those observed in rats.

Novel drugs and their targets in the potential treatment of diabetic retinopathy

Diabetic retinopathy (DR) is the most common complication of diabetes. It causes vision loss, and the incidence is increasing with the growth of the diabetes epidemic worldwide. Over the past few decades a number of clinical trials have confirmed that careful control of glycemia and blood pressure can reduce the risk of developing DR and control its progression. In recent years, many treatment options have been developed for clinical management of the complications of DR (e.g., proliferative DR and macular edema) using laser-based therapies, intravitreal corticosteroids and anti-vascular endothelial growth factors, and vitrectomy to remove scarring and hemorrhage, but all these have limited benefits. In this review, we highlight and discuss potential molecular targets and new approaches that have shown great promise for the treatment of DR. New drugs and strategies are based on targeting a number of hyperglycemia-induced metabolic stress pathways, oxidative stress and inflammatory pathways, the renin-angiotensin system, and neurodegeneration, in addition to the use of stem cells and ribonucleic acid interference (RNAi) technologies. At present, clinical trials of some of these newer drugs in humans are yet to begin or are in early stages. Together, the new therapeutic drugs and approaches discussed may control the incidence and progression of DR with greater efficacy and safety.

Deletion of aldose reductase from mice inhibits diabetes-induced retinal capillary degeneration and superoxide generation

Purpose

Pharmacologic inhibition of aldose reductase (AR) previously has been studied with respect to diabetic retinopathy with mixed results. Since drugs can have off-target effects, we studied the effects of AR deletion on the development and molecular abnormalities that contribute to diabetic retinopathy. Since recent data suggests an important role for leukocytes in the development of the retinopathy, we determined also if AR in leukocytes contributes to leukocyte-mediated death of retinal endothelial cells in diabetes.

Methods

Wild-type (WT; C57BL/6J) and AR deficient (AR^−/−) mice were made diabetic with streptozotocin. Mice were sacrificed at 2 and 10 months of diabetes to evaluate retinal vascular histopathology, to quantify retinal superoxide production and biochemical and physiological abnormalities in the retina, and to assess the number of retinal endothelial cells killed by blood leukocytes in a co-culture system.

Results

Diabetes in WT mice developed the expected degeneration of retinal capillaries, and increased generation of superoxide by the retina. Leukocytes from diabetic WT mice also killed more retinal endothelial cells than did leukocytes from nondiabetic animals (p<0.0001). Deletion of AR largely (P<0.05) inhibited the diabetes-induced degeneration of retinal capillaries, as well as the increase in superoxide production by retina. AR-deficiency significantly inhibited the diabetes-induced increase in expression of inducible nitric oxide synthase (iNOS) in retina, but had no significant effect on expression of intercellular adhesion molecule-1 (ICAM-1), phosphorylated p38 MAPK, or killing of retinal endothelial cells by leukocytes.

Conclusions

AR contributes to the degeneration of retinal capillaries in diabetic mice. Deletion of the enzyme inhibits the diabetes-induced increase in expression of iNOS and of superoxide production, but does not correct a variety of other pro-inflammatory abnormalities associated with the development of diabetic retinopathy.

Pathophysiology of diabetic retinopathy

Diabetes is now regarded as an epidemic, with the population of patients expected to rise to 380 million by 2025. Tragically, this will lead to approximately 4 million people around the world losing their sight from diabetic retinopathy, the leading cause of blindness in patients aged 20 to 74 years. The risk of development and progression of diabetic retinopathy is closely associated with the type and duration of diabetes, blood glucose, blood pressure, and possibly lipids. Although landmark cross-sectional studies have confirmed the strong relationship between chronic hyperglycaemia and the development and progression of diabetic retinopathy, the underlying mechanism of how hyperglycaemia causes retinal microvascular damage remains unclear. Continued research worldwide has focussed on understanding the pathogenic mechanisms with the ultimate goal to prevent DR. The aim of this paper is to introduce the multiple interconnecting biochemical pathways that have been proposed and tested as key contributors in the development of DR, namely, increased polyol pathway, activation of protein kinase C (PKC), increased expression of growth factors such as vascular endothelial growth factor (VEGF) and insulin-like growth factor-1 (IGF-1), haemodynamic changes, accelerated formation of advanced glycation endproducts (AGEs), oxidative stress, activation of the renin-angiotensin-aldosterone system (RAAS), and subclinical inflammation and capillary occlusion. New pharmacological therapies based on some of these underlying pathogenic mechanisms are also discussed.

Animal models of diabetic retinopathy: summary and comparison

Diabetic retinopathy (DR) is a microvascular complication associated with chronic exposure to hyperglycemia and is a major cause of blindness worldwide. Although clinical assessment and retinal autopsy of diabetic patients provide information on the features and progression of DR, its underlying pathophysiological mechanism cannot be deduced. In order to have a better understanding of the development of DR at the molecular and cellular levels, a variety of animal models have been developed. They include pharmacological induction of hyperglycemia and spontaneous diabetic rodents as well as models of angiogenesis without diabetes (to compensate for the absence of proliferative DR symptoms). In this review, we summarize the existing protocols to induce diabetes using STZ. We also describe and compare the pathological presentations, in both morphological and functional aspects, of the currently available DR animal models. The advantages and disadvantages of using different animals, ranging from zebrafish, rodents to other higher-order mammals, are also discussed. Until now, there is no single model that displays all the clinical features of DR as seen in human. Yet, with the understanding of the pathological findings in these animal models, researchers can select the most suitable models for mechanistic studies or drug screening.

Leukocytes regulate retinal capillary degeneration in the diabetic mouse via generation of leukotrienes

Understanding the early pathogenesis of DR may uncover new therapeutic targets to prevent or slow the progression of this sight-threatening disorder. We investigated the role of leukocyte-mediated generation of LTs in regulation of retinal capillary degeneration and inflammation in the diabetic mouse. We generated (1) chimeric mice that lacked the ability to generate LTs by transplanting 5LO-/- bone marrow cells into ND.WT mice and into SD.WT mice and (2) "control" chimeric mice by transplanting WT bone marrow cells into 5LO-/- mice or into WT mice. Retinas from diabetic chimeric mice with WT marrow demonstrated capillary degeneration to the same extent as retinas from diabetic, nonchimeric WT mice. In contrast, retinas from diabetic chimeric mice with 5LO-/- marrow developed significantly less capillary degeneration and pericyte loss (P<0.05). In the retinas from chimeric mice with WT marrow, diabetes induced a rise in leukocyte adherence to the microvasculature, expression of the NF-κB p65 subunit, and ICAM1, superoxide generation, and retinal microvascular permeability, yet these characteristic responses were blunted by >50% in diabetic chimeras containing 5LO-/- leukocytes (P<0.05). Our data suggest the critical involvement of leukocytes and LTs in the regulation of inflammation and capillary degeneration in DR.

Hypoxia-induced oxidative stress in ischemic retinopathy

Oxidative stress plays a crucial role in the pathogenesis of retinal ischemia/hypoxia, a complication of ocular diseases such as diabetic retinopathy (DR) and retinopathy of prematurity (ROP). Oxidative stress refers to the imbalance between the production of reactive oxygen species (ROS) and the ability to scavenge these ROS by endogenous antioxidative systems. Free radicals and ROS are implicated in the irreversible damage to cell membrane, DNA, and other cellular structures by oxidizing lipids, proteins, and nucleic acids. Anti-oxidants that can inhibit the oxidative processes can protect retinal cells from ischemic/hypoxic insults. In particular, treatment using anti-oxidants such as vitamin E and lutein, inhibition of nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) or related signaling pathways, and administration of catalase and superoxide dismutase (SOD) are possible therapeutic regimens for DR, ROP, and other retinal ischemic diseases. The role of oxidative stress in the pathogenesis of DR and ROP as well as the underlying mechanisms involved in the hypoxia/ischemia-induced oxidative damage is discussed. The information provided will be beneficial in understanding the underlying mechanisms involved in the pathogenesis of the diseases as well as in developing effective therapeutic interventions to treat oxidative stress-induced damages.

Recent advances in understanding the biochemical and molecular mechanism of diabetic retinopathy

One of the major complications in patients with diabetes is diabetic retinopathy (DR), a leading cause of blindness worldwide. It takes several years before any clinical signs of retinopathy appear in diabetic patients, which gives an ample opportunity for scientists to uncover biochemical and molecular mechanism implicated early in the development and progression of the disease. During the past few decades, research progress has been made in investigating the pathophysiology of the disease; however, due to nonavailability of human retinal samples at different stages of the disease and also due to lack of a proper animal model of DR, the exact molecular mechanism has not been elucidated, making therapeutic a difficult task. In this review article, we have discussed a number of diabetes-induced metabolites such as glucose, lipids, amino acids, and other related factors and molecules that are implicated in the pathophysiology of the DR. Furthermore, we have highlighted neurodegeneration and regulation of neurotrophic factors, being recognized as early events that may be involved in the pathology of the disease in the course of DR. An understanding of the biochemical and molecular changes especially early in the diabetic retina may lead to new and effective therapies towards prevention and amelioration of DR, which is important for the millions of individuals who already have or are likely to develop the disease before a cure becomes available.

Aldose reductase deficiency protects from autoimmune- and endotoxin-induced uveitis in mice

PURPOSE

To investigate the effect of aldose reductase (AR) deficiency in protecting the chronic experimental autoimmune (EAU) and acute endotoxin-induced uveitis (EIU) in c57BL/6 mice.

METHODS

The WT and AR-null (ARKO) mice were immunized with human interphotoreceptor retinoid-binding peptide (hIRPB-1-20), to induce EAU, or were injected subcutaneously with lipopolysaccharide (LPS; 100 μg) to induce EIU. The mice were killed on day 21 for EAU and at 24 hours for EIU, when the disease was at its peak, and the eyes were immediately enucleated for histologic and biochemical studies. Spleen-derived T-lymphocytes were used to study the antigen-specific immune response in vitro and in vivo.

RESULTS

In WT-EAU mice, severe damage to the retinal wall, especially to the photoreceptor layer was observed, corresponding to a pathologic score of ∼2, which was significantly prevented in the ARKO or AR inhibitor-treated mice. The levels of cytokines and chemokines increased markedly in the whole-eye homogenates of WT-EAU mice, but not in ARKO-EAU mice. Further, expression of inflammatory marker proteins such as inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, tumor necrosis factor (TNF)-α, and vascular cell adhesion molecule (VCAM)-1 was increased in the WT-EIU mouse eyes but not in the ARKO-EIU eyes. The T cells proliferated vigorously when exposed to the hIRPB antigen in vitro and secreted various cytokines and chemokines, which were significantly inhibited in the T cells isolated from the ARKO mice.

CONCLUSIONS

These findings suggest that AR-deficiency/inhibition protects against acute as well as chronic forms of ocular inflammatory complications such as uveitis.