The effects of atorvastatin in experimental autoimmune uveitis

Effects of atorvastatin on the function of Tenon's capsule fibroblasts in human eyes

PURPOSE

This study aimed to explore the role of atorvastatin (ATO) in the prevention and treatment of the scarring of filtration channels after glaucoma surgery.

METHODS

Human Tenon's capsule fibroblasts (HTFs) were co-cultured with various concentrations of ATO. First, Cell Counting Kit-8 assay was performed to evaluate the effects of various concentrations of ATO on the viability of HTFs. Then, after the ATO stimulated the HTFs for 24 h, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was performed to evaluate the apoptosis of HTFs. Transwell assay was also performed to evaluate the migration of HTFs. Moreover, enzyme-linked immunosorbent assay (ELISA) was performed to detect the protein expression levels of transforming growth factor-β1 (TGF-β1) and TGF-β2 in the cell culture supernatant of HTFs. Western blot was carried out to detect the protein expression levels of smooth muscle actin (SMA), p38, Smad3, fibronectin, collagen I and collagen III in different groups.

RESULTS

The results revealed that ATO could inhibit the proliferation and migration of HTFs. Based on the TUNEL assay, 100 μM and 150 μM ATO could induce cell apoptosis. The ELISA results indicated that ATO could down-regulate the expression level of TGF-β2, and western blot analysis revealed that the protein expression levels of SMA, p38, Smad3, fibronectin, collagen I and collagen III in the TGF-β2 group were all up-regulated compared with the control group, whereas the addition of ATO could reverse this up-regulation.

CONCLUSIONS

ATO could inhibit the proliferation and migration of HTFs and induce their apoptosis. It was preliminary proven that ATO could inhibit the signaling pathway induced by TGF-β. It is suggested that ATO could be a basis for the treatment of the scarring of filtration channels after glaucoma surgery.

Decoding the crosstalk between mevalonate metabolism and T cell function

The mevalonate pathway is an essential metabolic pathway in T cells regulating development, proliferation, survival, differentiation, and effector functions. The mevalonate pathway is a complex, branched pathway composed of many enzymes that ultimately generate cholesterol and nonsterol isoprenoids. T cells must tightly control metabolic flux through the branches of the mevalonate pathway to ensure sufficient isoprenoids and cholesterol are available to meet cellular demands. Unbalanced metabolite flux through the sterol or the nonsterol isoprenoid branch is metabolically inefficient and can have deleterious consequences for T cell fate and function. Accordingly, there is tight regulatory control over metabolic flux through the branches of this essential lipid synthetic pathway. In this review we provide an overview of how the branches of the mevalonate pathway are regulated in T cells and discuss our current understanding of the relationship between mevalonate metabolism, cholesterol homeostasis and T cell function.

Atorvastatin restores imbalance of cluster of differentiation 4 (CD4)+ T cells in immune thrombocytopenia in vivo and in vitro

Immune thrombocytopenia (ITP) is an autoimmune haemorrhagic disease, in which the overactivation of T cells is crucial in the pathogenesis. Atorvastatin (AT), a lipid-lowering medicine, has shown promising immunomodulatory effects in certain inflammatory conditions. However, the immunoregulatory role of AT in ITP remains elusive. To investigate the effect of AT in the treatment of ITP, cluster of differentiation 4 (CD4)⁺ T cells were isolated from patients with ITP and cultured with different dosages of AT. We found that AT significantly inhibited cell proliferation, led to cell cycle arrest, induced apoptosis, and repressed the activation of CD4⁺ T cells in vitro. ITP murine models were then established, and results showed that AT treatment led to faster recovery of the platelet count to normal and exhibited comparable immunomodulatory function. Furthermore, we found the phosphorylation of mammalian target of rapamycin (mTOR), protein kinase B (AKT) and extracellular signal-regulated kinase (ERK), as well as activation of rat sarcoma virus (RAS) were all reduced dramatically after AT treatment in vitro. In conclusion, our present study demonstrated that AT could reinstate the functions of CD4⁺ T cells by inhibiting the excessive activation, proliferation, and survival of CD4⁺ T cells in ITP via the RAS/mitogen-activated protein kinase kinase (MEK)/ERK and the mTOR/phosphatidylinositol-3 kinase (PI3K)/AKT pathway. Therefore, we propose that AT could be used as a potential therapeutic option for ITP by restoring the over-activated cellular immunity.

Decreased risk of non-infectious anterior uveitis with statin therapy in a large healthcare claims database

PURPOSE

The purpose of this study is to determine if statin therapy decreases the incidence of non-infectious uveitis (NIU) using a retrospective cohort study.

METHODS

Patients enrolled in a national insurance plan who initiated statin (n = 711,734, statin cohort) or other lipid-lowering therapy (n = 148,044, non-statin cohort) were observed for NIU development. Incident NIU in the primary analysis was defined as a new diagnosis code for NIU followed by a second instance of a NIU code within 120 days. For the secondary outcome definition, a corticosteroid prescription or code for an ocular corticosteroid injection within 120 days of the NIU diagnosis code was used instead of the second NIU diagnosis code. Estimation of NIU incidence used multivariable Cox proportional hazards regression. The proportional hazards assumption was satisfied by creating two time periods of analysis, ≤ 150 and > 150 days. Subanalyses were performed by anatomic subtype.

RESULTS

Overall, the primary outcome occurred 541 times over 690,465 person-years in the statin cohort and 103 times over 104,301 person-years in the non-statin cohort. No associations were seen in the ≤ 150-day analyses (p > 0.20 for all comparisons). However, after 150 days, the statin cohort was less likely to develop any uveitis [hazard ratio (HR) = 0.70, 95% confidence interval (CI): 0.51-0.97, P = 0.03] in the primary outcome analysis, but did not meet significance for the secondary outcome (HR = 0.85, 95% CI: 0.63-1.15, P = 0.30). Similarly, in the anatomic subtype analysis, after 150 days, the statin cohort was less likely to develop anterior uveitis (HR = 0.67, 95% CI: 0.47-0.97, P = 0.03) in the primary analysis, but the association did not reach significance for the secondary outcome (HR = 0.82, 95% CI: 0.56-1.20, P = 0.31).

CONCLUSION

Our results suggest that statin therapy for > 150 days decreases the incidence of NIU.

Statins in ophthalmology

Statins, 3-hydroxy-3-methyl-gutaryl coenzyme A reductase inhibitors, are a class of lipid-lowering drugs with anti-inflammatory, immunomodulatory, and vascular effects. Statins are increasingly being used in the treatment of a variety of medical conditions. We examine the actions of statins on the eye and its associated ophthalmic disorders. Statins can be synthetic or nonsynthetic, and their differentiating derivations may contribute to their varying cholesterol-lowering and pleiotropic effects. There is conflicting evidence on the ocular therapeutic and adverse effects of the statins. Statins may play a role in reducing the burden of dry eye, corneal ulcer scarring, thyroid-associated orbitopathy, glaucoma, uveitis and other associated ocular inflammatory states, cataract, proliferative vitreoretinopathy, diabetic retinopathy, macular degeneration, and choroidal melanoma. Topical preparations of statins can be formulated, thereby extending the range of ocular diseases that may be amenable to treatment. Statins have a relatively safe side effect profile, but rare and serious adverse reactions have been reported with their usage in ophthalmology, including myopathies and rhabdomyolysis with acute renal failure.

Controlled release of corticosteroid with biodegradable nanoparticles for treating experimental autoimmune uveitis

Noninfectious uveitis is a potentially blinding ocular condition that often requires treatment with corticosteroids to prevent inflammation-related ocular complications. Severe forms of uveitis such as panuveitis that affects the whole eye often require a combination of topical and either regional or systemic corticosteroid. Regional corticosteroids are currently delivered inside the eye by intravitreal injection (e.g. Ozurdex®, an intravitreal dexamethasone implant). Intravitreal injection is associated with rare but potentially serious side effects, including endophthalmitis, retinal and vitreous hemorrhage, and retinal detachment. Subconjunctival (SCT) injection is a less invasive option that is a common route used for post-surgical drug administration and treatment of infection and severe inflammation. However, it is the water soluble form of dexamethasone, dexamethasone sodium phosphate (DSP), that has been demonstrated to achieve high intraocular penetration with subconjunctival injection. It is difficult to load highly water soluble drugs, such as DSP, and achieve sustained drug release using conventional encapsulation methods. We found that use of carboxyl-terminated poly(lactic-co-glycolic acid) (PLGA) allowed encapsulation of DSP into biodegradable nanoparticles (NP) with relatively high drug content (6% w/w) if divalent zinc ions were used as an ionic "bridge" between the PLGA and DSP. DSP-Zn-NP had an average diameter of 210 nm, narrow particle size distribution (polydispersity index ~0.1), and near neutral surface charge (-9 mV). DSP-Zn-NP administered by SCT injection provided detectable DSP levels in both the anterior chamber and vitreous chamber of the eye for at least 3 weeks. In a rat model of experimental autoimmune uveitis (EAU), inflammation was significantly reduced in both the front and back of the eye in animals that received a single SCT injection of DSP-Zn-NP as compared to animals that received either aqueous DSP solution or phosphate buffered saline (PBS). DSP-Zn-NP efficacy was evidenced by a reduced clinical disease score, decreased expression of various inflammatory cytokines, and preserved retinal structure and function. Furthermore, SCT DSP-Zn-NP significantly reduced microglia cell density in the retina, a hallmark of EAU in rats. DSP-Zn-NP hold promise as a new strategy to treat noninfectious uveitis and potentially other ocular inflammatory disorders.

Immunotropic Effects and Proposed Mechanism of Action for 3-Hydroxy-3-methylglutaryl-coenzyme A Reductase Inhibitors (Statins)

Inhibitors of HMG-CoA reductase (statins) are the major group of lipid-lowering drugs. Along with hypocholesterolemic activity, statins exhibit anti-inflammatory and immunomodulatory properties that expand their clinical use, particularly, in the treatment of chronic inflammatory and autoimmune disorders. In this review, we critically analyze the data of statin effects on immune cells (e.g., monocytes and T cells) involved in the development of atherosclerosis and other chronic inflammatory diseases. We (i) discuss the properties of statins and routes of cell entry, as well as their major intracellular targets; (ii) evaluate the data on the effects of statins on the subset composition of circulatory monocytes, ability of monocytes to migrate to the site of inflammation (cell motility and expression of adhesion molecules and chemokine receptors), production of cytokines, matrix metalloproteinases, and reactive oxygen species by monocytes/macrophages, and antigen-presenting activity in peripheral blood monocyte-derived dendritic cells; and (iii) summarize the data on the regulation of proliferation and differentiation of various CD4+ T cell subsets (type 1/2/17 helper T cells and regulatory T cells) by statins.

Association between statin use and uveitis: results from the Pacific Ocular Inflammation study

PURPOSE

To assess whether there is a protective association between statin use and uveitis diagnosis.

DESIGN

Retrospective, population-based case-control study.

METHODS

Medical records of all patients in the Kaiser Permanente Hawaii health plan between January 1, 2006 and December 31, 2007 (N = 217 061) were searched electronically for International Classification of Diseases, 9th Revision, diagnosis codes related to uveitis. Chart review was done to confirm incident uveitis diagnosis during the study period. Two control groups were each randomly selected at a 5:1 ratio to cases, and controls were assigned an index date to match their respective case diagnosis date. One control group was selected from the general Kaiser Permanente Hawaii population that had at least 1 healthcare visit during the study period. Another control group was selected from the population of Kaiser Permanente Hawaii members who had at least 1 visit to the ophthalmology clinic during the study period. Statin use was defined as filling a prescription for statin medication in the year prior to the diagnosis or index date based on an electronic search of the Kaiser Permanente Hawaii pharmacy database for Generic Product Identification codes. A conditional logistic regression model with clinical diagnosis of uveitis as the outcome was used to assess the relationship between statin use and uveitis.

RESULTS

One hundred eight incident cases of uveitis were identified. Nineteen percent of uveitis patients had used statin medication in the year prior to diagnosis compared to 30% of patients in the general Kaiser population control (P = .03) and 38% of patients in the ophthalmology clinic control (P < .001). Using the general Kaiser population control and adjusting for age, sex, race, and autoimmune diseases, the odds of a statin user developing uveitis were 48% less than the odds of a non-statin user developing uveitis (OR: 0.52, 95% CI: 0.29-0.94, P = .03). Similarly, the odds of developing uveitis were 33% less for statin users compared to non-statin users (OR: 0.67, 95% CI: 0.38-1.19, P = .17) when adjusting for these factors and using the ophthalmology clinic control group.

CONCLUSIONS

Statin use may be protective against the development of uveitis. Several anti-inflammatory and immunomodulatory mechanisms may explain this association.

Neither T-helper type 2 nor Foxp3+ regulatory T cells are necessary for therapeutic benefit of atorvastatin in treatment of central nervous system autoimmunity

Oral atorvastatin has prevented or reversed paralysis in the multiple sclerosis (MS) model experimental autoimmune encephalomyelitis (EAE), and reduced development of new MS lesions in clinical trials. Besides inhibiting development of encephalitogenic T cells, atorvastatin treatment of EAE has been associated with an induction of anti-inflammatory myelin-reactive T-helper type (Th)-2 cells. To investigate the clinical significance of atorvastatin-mediated Th2 differentiation, we first evaluated atorvastatin treatment in interleukin (IL)-4 green fluorescent protein-enhanced transcript (4-GET) reporter mice. Atorvastatin treatment failed to induce IL-4-producing Th2 cells in vivo; however, when T cells from atorvastatin-treated 4-GET mice were reactivated in vitro, T cells preferentially differentiated into Th2 cells, while antigen-specific T-cell proliferation and secretion of proinflammatory cytokines (interferon gamma, IL-17, tumor necrosis factor and IL-12) were reduced. Oral atorvastatin also prevented or reversed EAE in signal transducer and activator of transcription 6-deficient (STAT6^−/−) mice, which cannot generate IL-4-producing Th2 cells. Further, atorvastatin treatment did not induce or expand Foxp3⁺ regulatory T cells in either wild-type or STAT6^−/− mice. In vivo proliferation of T cells, as measured by incorporation of bromodeoxyuridine, was inhibited in atorvastatin-treated wild-type and STAT6^−/− mice. These data imply that atorvastatin ameliorates central nervous system autoimmune disease primarily by inhibiting proliferation of proinflammatory encephalitogenic T cells, and not simply through induction of anti-inflammatory Th2 cells. This cytostatic effect may be a relevant mechanism of action when considering use of statins in MS and other inflammatory conditions.

Statin Modulation of Human T-Cell Proliferation, IL-1β and IL-17 Production, and IFN-γ T Cell Expression: Synergy with Conventional Immunosuppressive Agents

HMG-CoA reductase inhibitors (statins) have been demonstrated to be immunomodulatory for human immune-mediated disease and in experimental models. The aim of this study was to compare statin-mediated immunosuppressive effects on human T-cell responses in vitro with those of conventional immunosuppressives (dexamethasone, cyclosporin A (CsA), mycophenolate, and rapamycin). Statins (atorvastatin, lovastatin, and simvastatin) were investigated for their modulatory effects on human PBMC viability, cytokine profiles, and T-cell proliferation. At concentrations that inhibited anti-CD3/28-stimulated T-cell proliferation (P < 0.01), simvastatin significantly decreased intracellular CD4(+) T-cell expression of IFN-γ (P < 0.01) to levels similar to those induced by conventional immunosuppressives. Atorvastatin and lovastatin also decreased IFN-γ expression, although to a lesser degree (P < 0.05). All three statins reduced levels of IL-17 production (P < 0.01). However, in response to anti-CD3/28 stimulation, simvastatin significantly upregulated IL-1β production (P < 0.05). The profile of cytokines produced in response to anti-CD3/28 stimulation was similar when both atorvastatin and dexamethasone were added as compared with dexamethasone alone, suggesting that atorvastatin can synergise with dexamethasone with respect to immunomodulation of cytokines. This data supports the hypothesis of selective statin-mediated immunomodulatory effects on human immune cells.

Statin use and ocular inflammatory disease risk

Background

This study aims to evaluate the effect of oral statin medication use on the subsequent development of ocular inflammatory disease (OID). A retrospective nested case–control study was carried out on patient records from the Birmingham Veterans Affairs Medical Center. All male patients with a new diagnosis of OID over a 5-year period were included. Ten control subjects (without OID) were age-matched to each OID case. Prescription files of all subjects were queried for statin use. Information on selected comorbid medical conditions was also obtained. Conditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for risk of OID development in the context of statin use, controlling for comorbid conditions.

Results

Ninety-two incident cases of OID were identified. A trend toward a reduction in the risk of new OID development was found in patients that used statins compared to those that did not (OR 0.50, 95% CI 0.20 to 1.23, p = 0.13). The longer the duration of statin use, the greater is the effect.

Conclusions

Use of oral statins may be associated with a reduced risk for the development of OID. This reduced risk increases with increasing duration of use. Larger clinical studies would be required to definitively establish the effectiveness of statins in lowering the incidence of OID.

Expression Analysis of Cytokine and Chemokine Genes during the Natural Course of Murine Experimental Autoimmune Uveoretinitis

C57BL/6 mice were immunized with human interphotoreceptor retinoid-binding protein peptides to induce experimental autoimmune uveoretinitis (EAU). From the day of immunization to 30 days later, RNA was isolated daily from the mouse eyes. Dynamic changes in gene expression during the pathogenesis of EAU were analyzed by TaqMan gene expression assay that contained most chemokines/cytokines and their receptors, and signal transducer and activator of transcription (STAT) family genes, using beta-actin as the endogenous control. Gene clusters based on their expression profiles were analyzed to determine the candidate genes for the pathogenesis of inflammation. Hierarchical cluster analysis showed gene expression during EAU development in seven clustering patterns. Hierarchical cluster analysis also identified four distinct phases in daily expression: entrance, acceleration, deceleration, and remission. Gene expression changes in the EAU active phase showed synergetic upregulation of Th1-type genes (IFN-gamma and CXCL10/IP-10) with elevated Th2-type genes (CCL17/TARC and IL-5). Sequential expression changes of STAT1, STAT6, and STAT3 genes represented the dynamic changes of Th1, Th2, and Th17-type inflammatory genes, respectively. The expression pattern of STAT1 was representative of many gene movements. Our results suggested that coordinated action of Th1, Th2, and Th17 genes and STAT family genes are involved in EAU development and resolution.

Atorvastatin ameliorates experimental autoimmune neuritis by decreased Th1/Th17 cytokines and up-regulated T regulatory cells

Statins have anti-inflammatory and immune-regulating properties. To investigate the effects of atorvastatin on experimental autoimmune neuritis (EAN), an animal model of Guillain-Barré syndrome (GBS), atorvastatin was administered to Lewis rats immunized with bovine peripheral myelin in complete Freund's adjuvant. We found that atorvastatin ameliorated the clinical symptoms of EAN, decreased the numbers of inflammatory cells as well as IFN-γ(+) and IL-17(+) cells in sciatic nerves, decreased the CD80 expression and increased the number of CD25(+)Foxp3(+) cells in mononuclear cells (MNC), and decreased the levels of IFN-γ in MNC culture supernatants. These data provide strong evidence that atorvastatin can act as an inhibitor in EAN by inhibiting the immune response of Th1 and Th17, decreasing the expression of co-stimulatory molecule, and up-regulating the number of T regulatory cells. These data demonstrated that statins could be used as a therapeutic strategy in human GBS in future.

Role of statins in the treatment of multiple sclerosis: an update

SUMMARY This article discusses the role of statins in the treatment of multiple sclerosis. Statins are promising agents as adjunctive therapies in immune-mediated disorders such as multiple sclerosis owing to their immunomodulatory, anti-inflammtory and neuroprotective characteristics. On the other hand, there are some conflicting data that warrant further investigation before sound conclusions can be made. Clinical trials are planned and being conducted to help shed more light on the potential benefit and the optimal dose of statins in treating multiple sclerosis.

Emerging biologics in the treatment of uveitis

The pathogenic mechanisms underlying uveitis syndromes continue to be evaluated using animal models and in the clinical setting. As the complex interactions between ocular immune cells, proinflammatory cytokines, chemokines and cellular adhesion molecules are uncovered, targeted therapies directed against these immune mediators will continue to be developed. Traditional immunosuppressive medications, such as corticosteroids and steroid-sparing immunomodulatory agents, have demonstrated efficacy in the treatment of uveitic syndromes, but side effects and drug toxicities often limit the use of these medications. The biologic agents, a newer class of medications, target specific immune pathways and have demonstrated efficacy in rheumatologic, dermatologic and neurologic conditions. Biologic therapies (e.g., TNF-alpha inhibitors and IL-2 receptor inhibitor) targeting ocular immune cell surface receptors, cytokines and chemokines continue to be developed and have shown promise in the treatment of uveitis and ocular inflammatory diseases. Clinical and basic aspects of monoclonal antibody therapy for uveitis are presented in this review. Additional studies are needed to further evaluate the role of monoclonal antibodies in the therapeutic armamentarium for uveitis.

Atorvastatin enhances humoral immune responses but does not alter renal injury in experimental crescentic glomerulonephritis

AIM

Statins are widely used for their cholesterol-lowering effects and for prevention of cardiovascular disease. Evidence indicates that these drugs also have immunomodulatory and other non-lipid lowering effects, with studies suggesting benefit in some animal models of immune (particularly T helper (Th)1)-mediated inflammatory disease and their corresponding human disease counterparts. We sought to evaluate the immunomodulatory effects and therapeutic potential of atorvastatin in experimental crescentic glomerulonephritis, a Th1-predominant animal model of glomerulonephritis.

METHODS

Autologous phase, anti-glomerular basement membrane glomerulonephritis was induced in C57BL/6 mice by intravenous injection of sheep anti-mouse glomerular basement membrane globulin. Mice were administered atorvastatin (10 or 100 mg/kg) or control (phosphate-buffered saline) daily by oral gavage. Immune responses and renal injury were assessed after 21 days.

RESULTS

Compared with control-treated mice, treatment with atorvastatin did not alter renal injury (serum creatinine, proteinuria, glomerular crescent formation) or glomerular leukocytic infiltration (CD4(+) T cells or macrophages). Atorvastatin resulted in a dose-related increase in circulating serum antibody to the disease-inducing antigen but no differences in antigen-stimulated splenocyte production of Th1/Th2 cytokines. At the higher dose, atorvastatin also led to a significant reduction in apoptosis of splenic CD4(+) T lymphocytes.

CONCLUSION

This study demonstrates that statins modulate humoral responses and alter splenic CD4(+) T cell apoptosis. However, atorvastatin does not lead to significant changes in T helper cell polarization or renal injury in experimental crescentic glomerulonephritis.

Immunomodulation by statins: mechanisms and potential impact on autoimmune diseases

Statins are inhibitors of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) and they are the most effective agents for lowering cholesterol in clinical practice for the treatment of cardiovascular diseases. However, it has become clear that statins also have pleiotropic immunomodulatory effects in addition to their lipid-lowering properties. As a result, much attention has been focused on their potential as therapeutic agents for the treatment of inflammatory autoimmune diseases. In this review the effect of statins on the expression and function of a variety of immune-relevant molecules will be discussed alongside the underlying mechanisms that contribute to the immunomodulatory effects of statins.

Update on statin-mediated anti-inflammatory activities in atherosclerosis

Anti-inflammatory activities of statins in atherosclerosis have been well documented by both basic research and clinical studies. Statins have been introduced in the 1980s as 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors to block cholesterol synthesis and lower cholesterol serum levels. In the last three decades, statins have been shown to possess several anti-inflammatory and antioxidant activities resulting in the beneficial reduction of atherosclerotic processes and cardiovascular risk in both humans and animal models. Inflammatory intracellular pathways involving kinase phosphorylation and protein prenylation are modulated by statins. The same intracellular mechanisms might also cause statin-induced myotoxicity. In the present review, we will update evidence on statin-mediated regulation of inflammatory pathways in atherogenesis.

Simvastatin impairs humoral and cell-mediated immunity in mice by inhibiting lymphocyte homing, T-cell activation and antigen cross-presentation

Statins block the activity of HMG-CoA reductase, which catalyses the production of mevalonate, an intermediate in cholesterol biosynthesis, which is also a precursor of isoprenoids. In addition to lowering circulating cholesterol, these drugs display anti-inflammatory and immunomodulatory activities in vitro; however, their effects on the development of adaptive immune responses in vivo, as well as the underlying mechanisms, are as yet largely unknown. Here we investigated the outcome of simvastatin treatment on a number of processes, which together orchestrate adaptive immunity to specific antigen. Simvastatin treatment resulted in a marked reduction of T and B cells in spleen, lymph nodes and peripheral blood in mice. This effect could be ascribed principally to an impairment of lymphocyte homing to secondary lymphoid organs. In addition, simvastatin was found to strongly inhibit T-cell responses to the MHCI restricted hen ovalbumin peptide antigen SIINFEKL and to impair ovalbumin uptake and cross-presentation by MHCI. Simvastatin also suppressed antibody responses to immunization with ovalbumin and delayed-type hypersensitivity to allergens. These activities could be largely accounted for by the simvastatin-dependent inhibition of HMG-CoA reductase. The data provide novel mechanistic insight into the activities of simvastatin in the highly complex context of the immune response.

Advances in the diagnosis and immunotherapy for ocular inflammatory disease

Significant advances in the diagnosis and therapy for uveitis have been made to improve the quality of care for patients with ocular inflammatory diseases. While traditional ophthalmic examination techniques, fluorescein angiography, and optical coherence tomography continue to play a major role in the evaluation of patients with uveitis, the advent of spectral domain optical coherence tomography and fundus autofluorescence into clinical practice provides additional information about disease processes. Polymerase chain reaction and cytokine diagnostics have also continued to play a greater role in the evaluation of patients with inflammatory diseases. The biologic agents, a group of medications that targets cytokines and other soluble mediators of inflammation, have demonstrated promise in targeted immunotherapy for specific uveitic entities. Their ophthalmic indications have continued to expand, improving the therapeutic armentarium of uveitis specialists.

S-nitrosoglutathione Prevents Interphotoreceptor Retinoid-Binding Protein (IRBP161–180)-Induced Experimental Autoimmune Uveitis

PURPOSE

Experimental autoimmune uveitis (EAU), an animal model of human uveitis, is an organ-specific autoimmune disease mediated by various inflammatory cytokines. In particular, tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta and interferon (IFN)-gamma are known to play a role in its pathogenesis. S-nitrosothiol S-nitrosoglutathione (GSNO), a slow nitric oxide (NO) donor, was reported to have beneficial effects in inflammatory disease in ischemia-reperfusion injury. The efficacy of GSNO treatment on interphotoreceptor retinoid-binding protein (IRBP)-induced EAU was investigated, using functional, histologic, and immunologic readouts.

METHODS

Mice were immunized with a single injection of IRBP(161180) peptide to induce EAU, followed by a daily treatment with GSNO (1 mg/kg). Electroretinogram (ERG) analysis, histopathology, and immunologic responses to IRBP were analyzed. The effects of GSNO treatment on the antigen-specific T-cell recall responses and their cytokine production were determined.

RESULTS

A single immunization of IRBP(161180) peptide led to significant structural damage of the retina and concomitant elimination of ERGs. Daily oral GSNO treatment from days 1-14 following immunization was found to be effective against IRBP-induced EAU. Histopathologic and ERG analysis both demonstrated significant retinal protection in GSNO-treated mice. The GSNO treatment of EAU animals significantly attenuated the levels of TNF-alpha, IL-1beta, IFN-gamma, and IL-10 in retinas, as measured by quantitative real-time polymerase chain reaction analysis. The splenocytes isolated from EAU- and GSNO-treated mice had lower antigen-specific T-cell proliferation in response to IRBP protein, and their cytokine production was inhibited.

CONCLUSIONS

The oral administration of GSNO significantly suppressed the levels of inflammatory mediators in the retinas of EAU mice. This suppression was associated with the maintenance of normal retinal histology and function. These results clearly demonstrated the therapeutic potential of GSNO in EAU, and provide new insights for the treatment of human uveitis.

Treatment of experimental autoimmune uveoretinitis with atorvastatin and lovastatin

Statins, which are 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, are approved for cholesterol reduction and are commonly used to treat atherosclerosis and coronary artery disease. Statins may also be potent immunomodulatory agents and may be beneficial in the treatment of autoimmune diseases. In this study, we investigated therapeutic effects of atorvastatin and lovastatin on experimental autoimmune uveoretinitis (EAU). EAU was induced in Lewis rats using bovine S-antigen (S-Ag) peptide. Atorvastatin was suspended in 0.5% aqueous methylcellulose and was administered orally at a dose of 10 mg/kg and at a low-dose of 1 mg/kg. Lovastatin was dissolved in DMSO:PBS (1:1) and was administered by intraperitoneal (i.p.) injection at a dose of 2 mg/kg. Both statin treatments were initiated after the clinical onset once daily for 14 days. The rats were examined every other day for clinical signs of EAU. The histological scores and delayed-type hypersensitivity (DTH) were evaluated on day 28 post-immunization. Morphologic and immunohistochemical examinations were performed with light and confocal microscopy, respectively. Lymphocyte proliferation was measured by [(3)H]thymidine incorporation into antigen-stimulated T cells from inguinal lymph nodes. After 72 h, supernatants were collected and assayed for IFN-gamma by ELISA. Clinical and histological scores of EAU were decreased in both the atorvastatin (10 mg/kg)- and lovastatin (2 mg/kg)-treated groups. The invasion of T cells and macrophages, and Müller cell proliferation, were inhibited in both atorvastatin- and lovastatin-treated groups. DTH was significantly inhibited in both groups, compared with vehicle-treated groups (controls). Lymphocyte proliferation assay demonstrated decreased proliferation in the presence of 25 microg/ml S-Ag peptide in both groups, compared with controls. In the supernatants of lymph node cells stimulated with S-Ag peptide (5 microg/ml), 77 or 87% inhibition of IFN-gamma production was observed in rats treated with atorvastatin or lovastatin, respectively, compared with controls. The current results indicate that atorvastatin administrated orally following the clinical onset has therapeutic effect in EAU as well as lovastatin administrated intraperitoneally. Statins may be useful for treating intraocular inflammation.

Atorvastatin interferes with activation of human CD4(+) T cells via inhibition of small guanosine triphosphatase (GTPase) activity and caspase-independent apoptosis

Although a beneficial effect of hydroxy-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, i.e. statins, on cell-mediated immunity has been suggested in vivo and in vitro, little is known about the molecular and biochemical events by which statins inhibit T cell proliferation. To address this question, we investigated the effects of atorvastatin (AT) on intracellular cytokine production, T cell activation markers, cell cycle progression and apoptosis in human CD4(+) T cells. AT did not influence intracellular cytokine production after short-term stimulation of whole blood with phorbol myristate acetate (PMA)/ionomycin or superantigen (SEB). In contrast, AT influenced CD45RA to RO switching dose-dependently, as well as CD25 expression, and caused cell cycle arrest in the G1 phase after long-term T cell stimulation. This occurred in conjunction with a reduced expression of cyclin-dependent kinases 2 and 4 and p21(wav1/cip1) and was paralleled by an increased protein expression of p27(kip1). In addition to G1 arrest, increased apoptosis was observed in AT-treated cells. In line with this, the expression of Bcl-xl and pBad were decreased by AT. Apoptosis was independent of caspases 3 and 9 activation. The inhibitory effect of AT on T cell proliferation could be overcome by addition of mevalonic acid or geranylgeranyl pyrophosphate, but not by farnesyl pyrophosphate or squalen, suggesting reduced protein prenylation. Activation of Rho, Rac and Ras were strongly reduced in AT-treated T cells, suggesting that impaired geranylation of these molecules might underlie the inhibitory effect of AT on T cell proliferation.

The role of cytokines in the regulation of ocular autoimmune inflammation

The eye is a unique place for the development of an immune response. Beyond the usual mechanisms of immune restraint, the eye evolved with its exclusive mechanisms such as anterior chamber associated immune deviation. Therefore, immune-mediated inflammation in the eye does not develop at the same pace as in other sites of the body. Here we will address such peculiarities as they regard to ocular autoimmunity, using the experimental autoimmune uveitis as a model to understand the participation of cytokines in the process of aggression against the eye, as well as their immunoregulatory role.

Statin therapy and autoimmune disease: from protein prenylation to immunomodulation

Statins have been prescribed extensively for their cholesterol-lowering properties and efficacy in cardiovascular disease. However, compelling evidence now exists that statins also have extensive immunomodulatory properties that operate independently of lipid lowering. Consequently, much attention has been directed towards their potential as therapeutic agents for the treatment of autoimmune disease. Modulation of post-translational protein prenylation seems to be a key mechanism by which statins alter immune function. In this Review, the effect of statin therapy on immune function, and how this relates to the pathogenesis of autoimmune disease, is reviewed alongside current opinion of what the key biological targets of statins are.

Down-regulation of autoreactive T-cells by HMG CoA reductase inhibitors

The inhibitors of HMG CoA reductase (statins) are widely used as cholesterol-lowering drugs with excellent safety records in hypercholesterolemic patients. Statins exert pleiotropic effects on a variety of cells, and they were recently described as a new class of immune modulators. Depending on their structure, dose, and route of administration, statins regulate the function of both the antigen-presenting cells and T-cells by HMG CoA reductase-dependent and independent mechanisms. Herein, we describe these mechanisms leading to prevention, amelioration, and reversal of autoimmune diseases. We also present data from our laboratories showing for the first time that in a double transgenic mouse model for autoimmune diabetes, atorvastatin (lipitor) prevented the onset of disease when administered in the neonatal period, and stabilized the glucose levels when administered in mice developing a mild form of diabetes.