[Cytokines and their role in pathogenesis of diabetic retinopathy].

The role of cytokines is estimated in development of diabetic retinopathy. Titer of cytokines is compared in healthy subjects and patients with impaired glucose metabolism. Fundus examination and specific cytokines level assessment allowed us to conclude that cytokines directly take part in pathogenesis of retinopathy before clinical manifestation. It provides rational to use cytokine level as a predictor of early manifestation of diabetic retinopathy, its timely treatment and prevention of progressing till end stages.

Spotlight on statins.

Statins are among the most widely prescribed drugs to prevent cardiovascular morbidity. Over recent years, statins have also been shown to exert pleiotropic immunomodulatory effects that might be of therapeutic benefit in autoimmune disorders. Interestingly, the primary mechanism by which statins alter immune function appears to be largely independent of lipidlowering and mediated primarily through inhibition of post-translational prenylation of regulatory proteins. In experimental autoimmune encephalomyelitis, the mouse model for multiple sclerosis (MS), statins prevent and even reverse established paralysis. Furthermore, statins were recently shown to exert synergistic benefit in combination with some agents already approved for MS therapy. Based upon these encouraging results obtained in the animal model, statins are now being evaluated in clinical trials as potential therapy for MS.

[Myopathies under therapy with lipid-lowering agents]. / Myopathien unter der Therapie mit Lipidsenkern.

Myopathies ranging from myalgia to clinically asymptomatic creatine kinase (CK) elevation and to life-threatening rhabdomyolysis belong to the most important complications of lipid-lowering therapies with fibrates and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, i.e., statins. Rhabdomyolysis is a rare side effect of statin therapy with an estimated incidence of 0.2/1 million prescriptions. Myalgia and muscle cramps were reported by up to 5% of patients, but they were observed with the same percentage in controls receiving placebo. Due to increasing numbers of patients under lipid-lowering therapy, however, more and more patients present in neuromuscular units with the differential diagnosis of a fibrate- or statin-induced myopathy.

[Neurological aspects of systemic rheumatological disorders]. / Neurologische Aspekte systemisch-rheumatischer Erkrankungen.

There are a number of common aspects between rheumatology and neurology. First, many systemic rheumatic diseases also affect the central and peripheral nervous system as well as muscle causing characteristic symptom complexes. Second, there are similarities between neurological and rheumatological autoimmune diseases in terms of underlying pathomechanisms. Here the most important neurological aspects of rheumatological disorders including their diagnosis and therapy are highlighted.

[Cholesterol-reducing medications-a new therapeutic option for multiple sclerosis? Statins as immunomodulators]. / Cholesterinsenker-eine neue Therapieoption bei Multipler Sklerose?Statine als Immunmodulatoren.

Statins are inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, which is crucial for cholesterol biosynthesis, and are widely used as lipid-lowering agents. These drugs greatly reduce atherosclerosis and cardiovascular morbidity, which in the past was mainly attributed to their cholesterol-lowering properties. However, recent evidence suggests that statins are also potent immunomodulators. They exerted beneficial effects on animal models of experimental autoimmune encephalomyelitis and thus have therapeutic potential for multiple sclerosis. Their exact mechanism of action is still unclear. HMG-CoA-dependent effects and a direct effect on immune receptors are conceivable and are reviewed here.

Statins as immunomodulators: comparison with interferon-beta 1b in MS.

BACKGROUND: Recent data suggest that statins may be potent immunomodulatory agents. In order to evaluate the potential role of statins as immunomodulators in MS, the authors studied their immunologic effects in vitro and compared them to interferon (IFN)beta-1b. METHODS: Peripheral blood mononuclear cells (PBMC) obtained from untreated or IFN beta-1-treated patients with relapsing-remitting MS or from healthy donors (HD) and T cells were stimulated with concanavalin A, phytohemagglutinin, or antibody to CD3 in the presence of lovastatin, simvastatin, mevastatin, IFN beta-1b, or statins plus IFN beta-1b. The authors analyzed proliferative activity of T cells and B cells, cytokine production and release, activity of matrix metalloproteinases (MMP), and surface expression of activation markers, adhesion molecules, and chemokine receptors on both T and B cells. RESULTS: All three statins inhibited proliferation of stimulated PBMC in a dose-dependent manner, with simvastatin being the most potent, followed by lovastatin and mevastatin. IFN beta-1b showed a similar effect; statins and IFN beta-1b together added their inhibitory potentials. Furthermore, statins reduced the expression of activation-induced adhesion molecules on T cells, modified the T helper 1/T helper 2 cytokine balance, reduced MMP-9, and downregulated chemokine receptors on both B and T cells. Besides strong anti-inflammatory properties, statins also exhibited some proinflammatory effects. CONCLUSIONS: Statins are effective immunomodulators in vitro that merit evaluation as treatment for MS.

[Treatment of multiple sclerosis with glatiramer acetate. Current aspects of mechanisms of action, pharmacokinetics, adverse effect profile and clinical studies]. / Behandlung der Multiplen Sklerose mit Glatiramer-Azetat. Aktuelles zu Wirkungsmechanismen, Pharmakokinetik, Nebenwirkungsprofil und Studiensituation.

Glatiramer acetate (GA, Copaxone), a standardized mixture of synthetic polypeptides, has now been approved also in Germany for the treatment of relapsing-remitting multiple sclerosis (RR-MS). After it had been shown effective in suppression of experimental autoimmune encephalomyelitis (EAE), the animal model of multiple sclerosis (MS), it was evaluated in several clinical studies. In these studies, GA could alter the natural history of MS by both reducing the relapse rate and affecting disability. The clinical therapeutic effect of GA was consistent with the effect on magnetic resonance imaging-defined disease activity and burden in a recent multicenter study. As a daily standard dose, 20 mg of GA is injected subcutaneously. The induction of GA-reactive T-helper 2-like regulatory suppressor cells is thought to be the main mechanism of action. The most common adverse effects are mild injection site reactions. A remarkable but rare adverse effect is the only transient immediate post-injection systemic reaction manifested by flushing, chest tightness, palpitations, and dyspnea. Antibodies to GA which are induced during GA treatment do not interfere with its clinical effects.

Risk-benefit assessment of glatiramer acetate in multiple sclerosis.

Glatiramer acetate, formerly known as copolymer 1, is a mixture of synthetic polypeptides composed of four amino acids. Glatiramer acetate has been shown to be effective in preventing and suppressing experimental autoimmune encephalitis (EAE), the animal model of multiple sclerosis (MS). Therefore it was tested in several clinical studies, where it was found to slow the progression of disability and to reduce the relapse rate and the magnetic resonance imaging (MRI)-defined disease activity and burden in relapsing-remitting MS. As a daily standard dose, 20mg of glatiramer acetate is injected subcutaneously. After injection, glatiramer acetate undergoes rapid degradation to amino acids and shorter peptides; so it is not possible to measure any systemic plasma concentrations or excretion rates. Two major mechanisms have been proposed to explain the effects of glatiramer acetate in EAE and MS: the induction of glatiramer acetate-reactive T helper 2 (Th2)-like regulatory suppressive cells and the interference with T cell activation as an altered peptide ligand. The most common adverse effects were mild injection site reactions (erythema, inflammation and induration). The most remarkable adverse event is the acute and transient immediate postinjection reaction manifested by flushing, chest tightness, palpitations and dyspnoea. Other reported adverse effects are transient chest pain and lymphadenopathy. Antibodies to glatiramer acetate induced during treatment do not interfere with its clinical effects. In several controlled clinical studies, glatiramer acetate has been shown to provide consistent, reproducible clinical benefits in the target population of patients with relapsing-remitting MS. The safety profile and risk-benefit ratio are excellent. Overall, glatiramer acetate is very well tolerated and has an excellent risk-benefit profile in patients with relapsing-remitting MS.

Treatment of multiple sclerosis with Copaxone (COP): Elispot assay detects COP-induced interleukin-4 and interferon-gamma response in blood cells.

Copolymer-1 (Copaxone or COP) inhibits experimental allergic encephalomyelitis and has beneficial effects in multiple sclerosis. There is presently no practical in vitro assay for monitoring the immunological effects of COP. We used an automated, computer-assisted enzyme-linked immunoadsorbent spot assay for detecting COP-induced interferon-gamma (IFN-gamma)- and interleukin-4 (IL-4)-producing cells and a standard proliferation assay to assess the immunological response to COP in peripheral blood mononuclear cells from 20 healthy donors, 20 untreated multiple sclerosis patients and 20 COP-treated multiple sclerosis patients. Compared with untreated and healthy controls, COP-treated patients showed (i) a significant reduction of COP-induced proliferation; (ii) a positive IL-4 Elispot response mediated predominantly by CD4 cells after stimulation with a wide range of COP concentrations; and (iii) an elevated IFN-gamma response partially mediated by CD8 cells after stimulation with high COP concentrations. All three effects were COP-specific as they were not observed with the control antigens, tuberculin-purified protein or tetanus toxoid. The COP-induced changes were consistent over time and allowed correct identification of COP-treated and untreated donors in most cases. We propose that these criteria may be helpful to monitor the immunological response to COP in future clinical trials.

[Multiple sclerosis. Current review of failed and discontinued clinical trials of drug treatment]. / Multiple Sklerose. Aktuelle Ubersicht zu fehlgeschlagenen und abgebrochenen Therapiestudien.

Recent immunobiological findings together with advances in biotechnology, ameliorations in clinical trial design, and MRI developments have led to a variety of therapeutical approaches in multiple sclerosis (MS). However, in contrast to successfully introduced new treatments, a number of therapeutical failures exist as well: despite impressive data from animal models, convincing concepts, and promising phase I/II studies, some investigated drugs and strategies showed no positive effects in clinical trials, or trials had to be terminated because of unexpected side effects. This article provides an overview of clinical studies that have failed or been abandoned for other reasons. Tumor necrosis factor (TNF) alpha-antagonists which have led to negative effects in two studies (Lenercept, Infliximab) are discussed in detail. These results raise critical questions concerning the hypothetical pathogenesis of MS lesions and the value of MRI in the assessment of clinically relevant therapeutic drug effects. In addition to a description of the immunobiological background, studies on the immunosuppressive agents linomide, deoxyspergualin, sulfasalazine and cladribine, trials for the cytokines interleukin-10 and TGF-beta 2, the studies on remyelination by intravenous immunoglobulins (IVIg), oral tolerance, and extracorporeal photopheresis are discussed.

Multiple sclerosis: comparison of copolymer-1- reactive T cell lines from treated and untreated subjects reveals cytokine shift from T helper 1 to T helper 2 cells.

Copolymer 1 (COP), a standardized mixture of synthetic polypeptides consisting of l-glutamic acid, l-lysine, l-alanine, and l-tyrosine, has beneficial effects in multiple sclerosis and experimental autoimmune encephalomyelitis. We selected a panel of 721 COP-reactive T cell lines (TCL) from the blood of COP-treated and untreated multiple sclerosis patients and from healthy donors by using the split-well cloning technique. All TCL selected with COP proliferated in response to COP but not to myelin basic protein (MBP). Conversely, 31 control TCL selected with MBP proliferated in response to MBP but not to COP. We used intracellular double-immunofluorescence flow cytometry for quantitative analysis of cytokine production (IL-4, IFN-gamma) by the TCL. The majority of the COP-reactive TCL from untreated multiple sclerosis patients and normal donors predominantly produced IFN-gamma and, accordingly, were classified as T helper 1 cells (TH1). In contrast, the majority of the COP-reactive TCL from COP-treated patients predominantly (but not exclusively) produced IL-4-i.e., were TH2 (P < 0.05 as assessed by using a suitable preference intensity index). Longitudinal analyses revealed that the cytokine profile of COP-reactive TCL tends to shift from TH1 to TH2 during treatment. Interestingly, although there was no proliferative cross-reaction, about 10% of the COP-reactive TCL responded to MBP by secretion of small amounts of IL-4 or IFN-gamma, depending on the cytokine profile of the TCL. These results are consistent with a protective effect of COP-reactive TH2 cells. It is hypothesized that these cells are activated by COP in the periphery, migrate into the central nervous system, and produce immunomodulatory cytokines after local recognition of MBP.

Constitutive biological activity of thymus-independent TCR-alpha-beta+ intestinal intraepithelial lymphocytes in TCR-alpha-/- gene disruption mice.

The surface of alpha beta T cells express a heterodimeric T cell receptor (TCR) composed of an alpha- and a beta-chain. In TCR-alpha gene disruption mutant mice, T cells can be identified which surface-express the TCR-beta chain in the absence of the TCR-alpha chain. Characteristically, intestinal intraepithelial lymphocytes (i-IELs) constitutively express biological functions which are demonstrable after TCR ligation by mAb. We here describe a small, but distinct population of TCR-alpha-beta+ i-IEL in TCR-alpha-/- mice. These cells used a restricted V beta repertoire skewed towards V beta 8 or V beta 14 and most of them expressed the CD4 coreceptor. TCR-beta ligation by specific mAb induced cytolytic activity in these TCR-alpha-beta+ i-IELs. Our findings reveal that TCR-alpha-beta+ i-IELs express biological activities and suggest that they develop independent of the thymus.

Influence of beta 2-microglobulin expression on gamma interferon secretion and target cell lysis by intraepithelial lymphocytes during intestinal Listeria monocytogenes infection.

Numerous microbial pathogens, including Listeria monocytogenes, enter the host through the intestine. Although relatively little is known about the biological functions of intestinal intraepithelial lymphocytes (i-IEL), they are generally considered a first line of defense against intestinal infections. In the mouse, the vast majority of i-IEL express the CD8 coreceptor either as a CD8 alpha/alpha homodimer or as a CD8 alpha/beta heterodimer. The CD8 receptor of T-cell receptor TcR gamma/delta i-IEL is exclusively homodimeric, whereas the CD8-expressing TcR alpha/beta i-IEL segregate into equal fractions of CD8 alpha/alpha and CD8 alpha/beta cells. We infected beta 2-microglobulin (beta 2m)+/- mice (possessing all i-IEL populations) and beta 2m -/- mutant mice (lacking all CD8 alpha/beta + i-IEL and having few CD8 alpha/alpha + TcR alpha/beta i-IEL) with L. monocytogenes per os and determined their biological functions after TcR ligation with monoclonal antibodies. Cytolytic activities of TcR alpha/beta and TcR gamma/delta i-IEL from beta 2m +/- mice were not influenced by intestinal listeriosis. Cytolytic activities of TcR alpha/beta i-IEL were impaired in uninfected beta 2m -/- mice, but this reduction was reestablished as a consequence of intestinal listeriosis. Frequencies of gamma interferon (IFN-gamma)-producing TcR alpha/beta i-IEL in uninfected beta 2m -/- mice were reduced, compared with that in their heterozygous controls. Equally low frequencies of IFN-gamma-producing TcR gamma/delta i-IEL in beta 2M +/- and beta 2m-/- mutants were found. Listeriosis increased frequencies of INF-gamma-producing TcR alpha/beta and TcR gamma/delta i-IEL in both mouse strains. Most remarkably, the proportion of IFN-gamma-producing TcR gamma/delta i-IEL was elevated 10-fold in listeria-infected beta 2M -/- mice. Our findings show that the beta 2m-independent CD8 beta- i-IEL expressing either TcR alpha/beta or TcR gamma/delta are stimulated by intestinal listeriosis independent of regional beta 2m expression. We conclude that the three major CD8+ i-IEL populations are stimulated by intestinal listeriosis and that CD8 beta- i-IEL compensate for the total lack of CD8 beta+ i-IEL in beta 2M -/- mutant mice. Hence, in contrast to the peripheral immune system, which crucially depends on CD8 alpha/beta + TcR alpha/beta lymphocytes, the mucosal immune system can rely on additional lymphocytes expressing the CD8 alpha/alpha homodimer.

Control of thymus-independent intestinal intraepithelial lymphocytes by beta 2-microglobulin.

Murine intestinal intraepithelial lymphocytes (i-IEL) comprise thymus-dependent cells such as T cell receptor (TcR) alpha/beta CD8 alpha/beta+ i-IEL, as well as thymus-independent ones such as TcR alpha/beta CD8 alpha/alpha+ and TcR gamma/delta CD8 alpha/alpha+ i-IEL. Whilst the development of the CD8 alpha/beta expressing i-IEL is strictly contingent on major histocompatibility complex (MHC) class I surface expression, that of CD8 alpha/alpha i-IEL appears largely MHC class I independent. We have used beta 2-microglobulin (beta 2m)-/- mutant mice lacking surface-expressed MHC class I and TcR alpha/beta CD8 alpha/beta+ i-IEL to analyze the potential impact of MHC class I on regional activation of thymus-independent i-IEL. To analyze the role of TcR gamma/delta i-IEL in regional cell interactions, these mice were treated with the anti-TcR gamma/delta mAb, GL3. Whilst numbers of TcR alpha/beta CD8 alpha/alpha i-IEL were markedly reduced in beta 2m-/- mice, those of TcR gamma/delta i-IEL were elevated. Administration of GL3 in vivo caused TcR down-modulation and functional inactivation of TcR gamma/delta i-IEL in beta 2m+/- mice. In contrast, TcR expression and functional activities of TcR gamma/delta i-IEL from beta 2m-/- mice were not impaired by GL3 treatment. The TcR alpha/beta CD8 beta- i-IEL from beta 2m-/- mice were expanded and functionally activated as a consequence of TcR gamma/delta engagement. The TcR gamma/delta i-IEL and TcR alpha/beta CD8 alpha/alpha+ i-IEL from athymic nu/nu mice which express MHC class I, but lack TcR alpha/beta CD8 alpha/beta+ i-IEL, responded to TcR gamma/delta engagement as those from the beta 2m+/- controls. In addition, the TcR gamma/delta i-IEL from TcR beta-/- and TCR beta+/- mutants were equally affected by GL3. We conclude that the absence of beta 2m renders TcR gamma/delta i-IEL resistant to TcR-mediated inactivation and promotes activation of TcR alpha/beta CD8 beta- i-IEL. The activation of TcR gamma/delta i-IEL seems to be directly controlled by beta 2m/MHC class I expression and independent from TcR alpha/beta CD8 beta+ i-IEL. Regulation of self-reactive thymus-independent i-IEL through beta 2m/ MHC class I may contribute to control of autoreactive immune responses in the intestine.

Renal reabsorptive capacity for alpha 2u-globulin in the adult male rat.

Adult male rats were maintained on 0, 5, 10, 15, and 20% casein diets to produce a series of animals having serum alpha 2u-globulin levels varying linearly from a normal of 31 micrograms/ml to a minimum of 13 micrograms/ml. In this way, it was possible to titrate endogenously the renal reabsorption and urinary excretion of this low molecular weight protein. The average maximal reabsorption rate (Tm) was established to be 9.7 micrograms/min and was reached at a renal filtered load (F alpha 2u) of 13.6 micrograms/min. These data were expressed in terms of a Tm:F alpha 2u ratio of 0.71. Below this value, the reabsorption declined from 70% to 50% of the F alpha 2u. Above 0.71, where F alpha 2u is less than the Tm, the reabsorption increased to 80-90%. It was observed that the fractional renal uptake of the alpha 2u-globulin varied linearly with the filtered load.