Eomesodermin-expressing T-helper cells are essential for chronic neuroinflammation

Development of acute experimental autoimmune encephalomyelitis (EAE) depends on Th17 cells expressing the nuclear factor NR4A2. However, in mice lacking NR4A2 in T cells, a late-onset disease is still inducible, despite a great reduction in acute inflammation. We here reveal that development of this late onset disease depends on cytotoxic T-cell-like CD4(+) T cells expressing the T-box transcription factor Eomesodermin (Eomes). T-cell-specific deletion of the Eomes gene remarkably ameliorates the late-onset EAE. Strikingly, similar Eomes(+) CD4(+) T cells are increased in the peripheral blood and cerebrospinal fluid from patients in a progressive state of multiple sclerosis. Collective data indicate an involvement of granzyme B and protease-activated receptor-1 in the neuroinflammation mediated by Eomes(+) CD4(+) T cells.

Potential role of nuclear receptor ligand all-trans retinoic acids in the treatment of fungal keratitis

Fungal keratitis (FK) is a worldwide visual impairment disease. This infectious fungus initiates the primary innate immune response and, later the adaptive immune response. The inflammatory process is related to a variety of immune cells, including macrophages, helper T cells, neutrophils, dendritic cells, and Treg cells, and is associated with proinflammatory, chemotactic and regulatory cytokines. All-trans retinoic acids (ATRA) have diverse immunomodulatory actions in a number of inflammatory and autoimmune conditions. These retinoids regulate the transcriptional levels of target genes through the activation of nuclear receptors. Retinoic acid receptor α (RAR α), retinoic acid receptor γ (RAR γ), and retinoid X receptor α (RXR α) are expressed in the cornea and immune cells. This paper summarizes new findings regarding ATRA in immune and inflammatory diseases and analyzes the perspective application of ATRA in FK.

Synergistic effects of atorvastatin and all-trans retinoic acid in ameliorating animal model of multiple sclerosis

One suitable approach to enhancing multiple sclerosis (MS) treatment is combination of available medications to provide more desirable outcomes. Immunomodulatory effects of atorvastatin and/or all-trans retinoic acid (ATRA) were determined in previous studies. The present study was set out to investigate the synergistic effects of combination therapy by suboptimal doses of atorvastatin and ATRA in experimental autoimmune encephalomyelitis (EAE), an animal model of MS. EAE was induced by MOG35-55 in female C57BL/6 mice. Therapies were initiated at day 12 post immunization when the mice developed a disability score and continued throughout the study until the day 33 when animals were sacrificed. Therapeutic treatment with half doses of atorvastatin and ATRA in combination has synergistic benefits causing the regression of clinical and neuropathological features of EAE more favorable than treatment with full doses of either drug alone. Without any advantage in anti-proliferative effect, combination treatment significantly reduced the secretion of pro-inflammatory cytokine interleukin-17 and conversely, increased the production of anti-inflammatory cytokine interleukin-10 more prominent than either drug alone. Furthermore, FoxP3+Treg cells were significantly increased only in combination treatment. In conclusion, combined atorvastatin and ATRA have immunomodulatory synergistic benefits and this pharmacological approach may be as a useful strategy to control MS.

The effect of vitamin A supplementation on retinoic acid-related orphan receptor γt (RORγt) and interleukin-17 (IL-17) gene expression in Avonex-treated multiple sclerotic patients

The aim of this study was to investigate the role of vitamin A on RORγt and IL-17 gene expression in multiple sclerotic patients. Patients in the vitamin A group received 25,000 IU retinyl palmitate per day, while patients in the placebo group took one capsule of placebo per day for 6 months. Gene expression was measured by real-time PCR at the first and end of the study. The results of this study show that vitamin A downregulates IL-17 and RORγt gene expression. No changes in gene expression occurred in the placebo group.

Recent developments in basophil research: do basophils initiate and perpetuate type 2 T-helper cell responses?

Basophils account for only 0.1-1% of all peripheral blood leukocytes. They were considered to be a redundant cell type for a long time. However, several findings show a non-redundant role for basophils in type 2 T-helper cell (Th2) immune responses in helminth infections, allergy and autoimmunity. Both immunoglobulin-E-dependent and -independent pathways have been described to contribute to basophil activation. In addition, several recent studies reported that basophils can function as antigen-presenting cells and are important in the initiation of Th2 immune responses. However, there are also conflicting studies that do not corroborate the importance of basophils in Th2 immune responses. This review discusses the role of basophils in Th2 immune responses in view of these recent findings.

LIM kinase 1 - dependent cofilin 1 pathway and actin dynamics mediate nuclear retinoid receptor function in T lymphocytes

Background

It is known that retinoid receptor function is attenuated during T cell activation, a phenomenon that involves actin remodeling, suggesting that actin modification may play a role in such inhibition. Here we have investigated the role of actin dynamics and the effect of actin cytoskeleton modifying agents on retinoid receptor-mediated transactivation.

Results

Agents that disturb the F-actin assembly or disassembly attenuated receptor-mediated transcription indicating that actin cytoskeletal homeostasis is important for retinoid receptor function. Overexpression or siRNA-induced knockdown of cofilin-1 (CFL1), a key regulator of F-actin assembly, induced the loss of receptor function. In addition, expression of either constitutively active or inactive/dominant-negative mutants of CFL1or CFL1 kinase LIMK1 induced loss of receptor function suggesting a critical role of the LIMK1-mediated CFL1 pathway in receptor-dependent transcription. Further evidence of the role of LMK1/CFL1-mediated actin dynamics, was provided by studying the effect of Nef, an actin modifying HIV-1 protein, on receptor function. Expression of Nef induced phosphorylation of CFL1 at serine 3 and LIMK1 at threonine 508, inhibited retinoid-receptor mediated reporter activity, and the expression of a number of genes that contain retinoid receptor binding sites in their promoters. The results suggest that the Nef-mediated inhibition of receptor function encompasses deregulation of actin filament dynamics by LIMK1 activation and phosphorylation of CFL1.

Conclusion

We have identified a critical role of LIMK1-mediated CFL1 pathway and actin dynamics in modulating retinoid receptor mediated function and shown that LIMK1-mediated phosphocycling of CFL1 plays a crucial role in maintaining actin homeostasis and receptor activity. We suggest that T cell activation-induced repression of nuclear receptor-dependent transactivation is in part through the modification of actin dynamics.

Experimental autoimmune encephalomyelitis as a testing paradigm for adjuvants and vaccines

Experimental autoimmune encephalomyelitis (EAE) is an experimental model for multiple sclerosis. EAE can be induced by inoculation with central nervous system (CNS) proteins or peptides emulsified in complete Freund's adjuvant. Protection from EAE, enhancement of EAE or subclinical priming for EAE can occur as a result of either live viral infection or DNA immunization with molecular mimics of CNS proteins or peptides. Here we review the published data describing modulation of EAE through administration of various CNS proteins/peptides introduced via live virus or plasmid DNA and modulation of EAE through choice of adjuvant (immunostimulating agents).

Studies in the modulation of experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE), an experimental model for multiple sclerosis, can be induced through inoculation with several different central nervous system (CNS) proteins or peptides. Modulation of EAE, resulting in either protection from EAE or enhancement of EAE, can also be accomplished through either vaccination or DNA immunization with molecular mimics of self-CNS proteins. Previously published data on this method of EAE modulation will be reviewed. New data is presented, which demonstrates that EAE can also be modulated through the administration of the beta-(1,3)-D-glucan, curdlan. Dendritic cells stimulated by curdlan are involved in the differentiation of the interleukin-17 producing subset of CD4(+) T cells that are recognized effector cells in EAE. Using two different systems to study the effects of curdlan on EAE, it was found that curdlan increased the incidence of EAE and/or the severity of the disease course.