Linkage disequilibrium analysis of chromosome 12q14-15 in multiple sclerosis: delineation of a 118-kb interval around interferon-gamma (IFNG) that is involved in male versus female differential susceptibility

Berberine: A natural modulator of immune cells in multiple sclerosis

Berberine is a benzylisoquinoline alkaloid found in such plants as Berberis vulgaris, Berberis aristata, and others, revealing a variety of pharmacological properties as a result of interacting with different cellular and molecular targets. Recent studies have shown the immunomodulatory effects of Berberine which result from its impacts on immune cells and immune response mediators such as diverse T lymphocyte subsets, dendritic cells (DCs), and different inflammatory cytokines. Multiple sclerosis (MS) is a chronic disabling and neurodegenerative disease of the central nervous system (CNS) characterized by the recruitment of autoreactive T cells into the CNS causing demyelination, axonal damage, and oligodendrocyte loss. There have been considerable changes discovered in MS regards to the function and frequency of T cell subsets such as Th1 cells, Th17 cells, Th2 cells, Treg cells, and DCs. In the current research, we reviewed the outcomes of in vitro, experimental, and clinical investigations concerning the modulatory effects that Berberine provides on the function and numbers of T cell subsets and DCs, as well as important cytokines that are involved in MS.

Aid or Antagonize: Nuclear Long Noncoding RNAs Regulate Host Responses and Outcomes of Viral Infections

Long noncoding RNAs (lncRNAs) are transcripts measuring >200 bp in length and devoid of protein-coding potential. LncRNAs exceed the number of protein-coding mRNAs and regulate cellular, developmental, and immune pathways through diverse molecular mechanisms. In recent years, lncRNAs have emerged as epigenetic regulators with prominent roles in health and disease. Many lncRNAs, either host or virus-encoded, have been implicated in critical cellular defense processes, such as cytokine and antiviral gene expression, the regulation of cell signaling pathways, and the activation of transcription factors. In addition, cellular and viral lncRNAs regulate virus gene expression. Viral infections and associated immune responses alter the expression of host lncRNAs regulating immune responses, host metabolism, and viral replication. The influence of lncRNAs on the pathogenesis and outcomes of viral infections is being widely explored because virus-induced lncRNAs can serve as diagnostic and therapeutic targets. Future studies should focus on thoroughly characterizing lncRNA expressions in virus-infected primary cells, investigating their role in disease prognosis, and developing biologically relevant animal or organoid models to determine their suitability for specific therapeutic targeting. Many cellular and viral lncRNAs localize in the nucleus and epigenetically modulate viral transcription, latency, and host responses to infection. In this review, we provide an overview of the role of nuclear lncRNAs in the pathogenesis and outcomes of viral infections, such as the Influenza A virus, Sendai Virus, Respiratory Syncytial Virus, Hepatitis C virus, Human Immunodeficiency Virus, and Herpes Simplex Virus. We also address significant advances and barriers in characterizing lncRNA function and explore the potential of lncRNAs as therapeutic targets.

Immune Cell Contributors to the Female Sex Bias in Multiple Sclerosis and Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is a chronic, autoimmune, demyelinating disease of the central nervous system (CNS) that leads to axonal damage and accumulation of disability. Relapsing-remitting MS (RR-MS) is the most frequent presentation of MS and this form of MS is three times more prevalent in females than in males. This female bias in MS is apparent only after puberty, suggesting a role for sex hormones in this regulation; however, very little is known of the biological mechanisms that underpin the sex difference in MS onset. Experimental autoimmune encephalomyelitis (EAE) is an animal model of RR-MS that presents more severely in females in certain mouse strains and thus has been useful to study sex differences in CNS autoimmunity. Here, we overview the immunopathogenesis of MS and EAE and how immune mechanisms in these diseases differ between a male and female. We further describe how females exhibit more robust myelin-specific T helper (Th) 1 immunity in MS and EAE and how this sex bias in Th cells is conveyed by sex hormone effects on the T cells, antigen presenting cells, regulatory T cells, and innate lymphoid cell populations.

IL-26 gene variants and protein expression in Tunisian asthmatic patients

The interleukin-26 (IL-26), a member of the IL-10 family is one of the latest discovered cytokines which contributes in numerous chronic autoimmune and inflammatory disorders. In the current case-control study, we investigated the distribution of three IL-26 single nucleotide polymorphisms (SNPs) (rs7134599, rs2870946 & rs1558744) in 440 Tunisian adults via Taqman genotyping assay. The presence of rs7134599 and rs1558744 polymorphisms considerably reduced the risk of developing asthma while the rs7134599 AA [OR = 0.40, CI: 0.23-0.70] and AG [OR = 0.50, CI (0.32-0.76)] genotypes protected against the asthma risk. The rs7134599 A allele was correlated with a lower risk of developing severe asthma (p < 0.001) while that of the rs2870946 CC genotype was associated with a higher risk of developing asthma in smoking patients (p < 0.001). In addition, we measured the IL-26 levels in the serum by an Enzyme-linked-Immunosorbent Assay (ELISA). During the analysis, we found that IL-26 serum levels were incredibly increased in asthmatic patients compared to the healthy controls. Our study revealed a significant association of IL-26 gene polymorphisms with asthma for the first time which can serve as biomarkers for asthma in the Tunisian population. The significant increase of IL-26 serum protein levels in asthma patients suggested a major role of IL-26 in asthma phenotypes.

IL-26, a Cytokine With Roles in Extracellular DNA-Induced Inflammation and Microbial Defense

Interleukin 26 (IL-26) is the most recently identified member of the IL-20 cytokine subfamily, and is a novel mediator of inflammation overexpressed in activated or transformed T cells. Novel properties have recently been assigned to IL-26, owing to its non-conventional cationic, and amphipathic features. IL-26 binds to DNA released from damaged cells and, as a carrier molecule for extracellular DNA, links DNA to inflammation. This observation suggests that IL-26 may act both as a driver and an effector of inflammation, leading to the establishment of a deleterious amplification loop and, ultimately, sustained inflammation. Thus, IL-26 emerges as an important mediator in local immunity/inflammation. The dysregulated expression and extracellular DNA carrier capacity of IL-26 may have profound consequences for the chronicity of inflammation. IL-26 also exhibits direct antimicrobial properties. This review summarizes recent advances on the biology of IL-26 and discusses its roles as a novel kinocidin.

Effector T Cells in Multiple Sclerosis

Multiple sclerosis (MS) has long been considered a CD4 T-cell disease, primarily because of the findings that the strongest genetic risk for MS is the major histocompatibility complex (MHC) class II locus, and that T cells play a central role in directing the immune response. The importance that the T helper (Th)1 cytokine, interferon γ (IFN-γ), and the Th17 cytokine, interleukin (IL)-17, play in MS pathogenesis is indicated by recent clinical trial data by the enhanced presence of Th1/Th17 cells in central nervous system (CNS) tissue, cerebrospinal fluid (CSF), and blood, and by research on animal models of MS, such as experimental autoimmune encephalomyelitis (EAE). Although the majority of research on MS pathogenesis has centered on the role of effector CD4 T cells, accumulating data suggests that CD8 T cells may play a significant role in the human disease. In fact, in contrast to most animal models, the primary T cell found in the CNS in patients with MS, is the CD8 T cell. As patient-derived effector T cells are also resistant to mechanisms of dominant tolerance such as that induced by interaction with regulatory T cells (Tregs), their reduced response to regulation may also contribute to the unchecked effector T-cell activity in patients with MS. These concepts will be discussed below.

IFNA-AS1 regulates CD4+ T cell activation in myasthenia gravis though HLA-DRB1

Abnormal CD4⁺T cell activation is known to play roles in the pathogenesis of myasthenia gravis (MG). However, little is known about the mechanisms underlying the roles of lncRNAs in regulating CD4⁺ T cell. In this study, we discovered that the lncRNA IFNG-AS1 is abnormally expressed in MG patients associated with quantitative myasthenia gravis (QMG) and the positive anti-AchR Ab levels patients. IFNG-AS1 influenced Th1/Treg cell proliferation and regulated the expression levels of their transcription factors in an experimental autoimmune myasthenia gravis (EAMG)model. IFNG-AS1 could reduce the expression of HLA-DRB and HLA-DOB and they had a negative correlation in MG. Furthermore IFNG-AS1 influenced the expression levels of CD40L and CD4⁺ T cells activation in MG patient partly depend on effecting the HLA-DRB1 expression. It suggests that IFNG-AS1 may be involved in CD4⁺T cell-mediated immune responses in MG.

Targeting Th17 Effector Cytokines for the Treatment of Autoimmune Diseases

Interleukin (IL)-17-producing T cells, especially T helper (Th)17 cells, play a critical role in the pathogenesis of a variety of autoimmune inflammatory diseases. The pathogenic function of Th17 cells results from their production of Th17 effector cytokines, namely IL-17 (or IL-17A), IL-17F, IL-22 and IL-26. The importance of IL-17 has been demonstrated by antibody neutralization studies in both animal models of autoimmune diseases as well as in human clinical trials. This review highlights the current knowledge of the clinical aspects of the Th17 cytokines as well as therapeutic antibodies against IL-17, IL-17F, IL-17 receptor, IL-22, IL-26 and granulocyte macrophage colony-stimulating factor for the future treatment of autoimmune inflammatory diseases.

The cationic cytokine IL-26 differentially modulates virus infection in culture

Interleukin-26 (IL-26) belongs to the IL-10 cytokine family, is produced by activated T cells, and targets epithelial target cells for signal transduction. Here, we describe the IL-26 effects on the infection of culture cells with recombinant vesicular stomatitis virus (VSV), human cytomegalovirus (HCMV), and herpes simplex virus type 1 (HSV-1) expressing green fluorescent protein. After pre-incubation with recombinant IL-26 and at low multiplicity of infection, VSV showed strongly enhanced infection and replication rates as measured for infectivity, for transcript levels, and for protein expression. Control proteins did not affect VSV infection. The IL-26 effect was independent of the IL-26 receptor and neutralized by anti-IL-26 serum. Pre-incubation of VSV was much more efficient than pre-incubation of the target cells to enhance virus infection. IL-26 increased virus adsorption to target cells as shown by quantitative reverse-transcription PCR. In contrast, the infection of IL-26-treated human fibroblasts with HCMV was inhibited and the infection by HSV-1 was not altered by IL-26. Thus, IL-26 differentially modulates the infection by different enveloped viruses.

The NeST long ncRNA controls microbial susceptibility and epigenetic activation of the interferon-γ locus

Long noncoding RNAs (lncRNAs) are increasingly appreciated as regulators of cell-specific gene expression. Here, an enhancer-like lncRNA termed NeST (nettoie Salmonella pas Theiler's [cleanup Salmonella not Theiler's]) is shown to be causal for all phenotypes conferred by murine viral susceptibility locus Tmevp3. This locus was defined by crosses between SJL/J and B10.S mice and contains several candidate genes, including NeST. The SJL/J-derived locus confers higher lncRNA expression, increased interferon-γ (IFN-γ) abundance in activated CD8(+) T cells, increased Theiler's virus persistence, and decreased Salmonella enterica pathogenesis. Transgenic expression of NeST lncRNA alone was sufficient to confer all phenotypes of the SJL/J locus. NeST RNA was found to bind WDR5, a component of the histone H3 lysine 4 methyltransferase complex, and to alter histone 3 methylation at the IFN-γ locus. Thus, this lncRNA regulates epigenetic marking of IFN-γ-encoding chromatin, expression of IFN-γ, and susceptibility to a viral and a bacterial pathogen.

The Ifng gene is essential for Vdr gene expression and vitamin D₃-mediated reduction of the pathogenic T cell burden in the central nervous system in experimental autoimmune encephalomyelitis, a multiple sclerosis model

Compelling evidence suggests that vitamin D3 insufficiency may contribute causally to multiple sclerosis (MS) risk. Experimental autoimmune encephalomyelitis (EAE) research firmly supports this hypothesis. Vitamin D3 supports 1,25-dihydroxyvitamin D3 (1,25-[OH]2D3) synthesis in the CNS, initiating biological processes that reduce pathogenic CD4+ T cell longevity. MS is prevalent in Sardinia despite high ambient UV irradiation, challenging the vitamin D-MS hypothesis. Sardinian MS patients frequently carry a low Ifng expresser allele, suggesting that inadequate IFN-γ may undermine vitamin D3-mediated inhibition of demyelinating disease. Testing this hypothesis, we found vitamin D3 failed to inhibit EAE in female Ifng knockout (GKO) mice, unlike wild-type mice. The two strains did not differ in Cyp27b1 and Cyp24a1 gene expression, implying equivalent vitamin D3 metabolism in the CNS. The 1,25-(OH)2D3 inhibited EAE in both strains, but 2-fold more 1,25-(OH)2D3 was needed in GKO mice, causing hypercalcemic toxicity. Unexpectedly, GKO mice had very low Vdr gene expression in the CNS. Injecting IFN-γ intracranially into adult mice did not increase Vdr gene expression. Correlating with low Vdr expression, GKO mice had more numerous pathogenic Th1 and Th17 cells in the CNS, and 1,25-(OH)2D3 reduced these cells in GKO and wild-type mice without altering Foxp3+ regulatory T cells. Thus, the Ifng gene was needed for CNS Vdr gene expression and vitamin D3-dependent mechanisms that inhibit EAE. Individuals with inadequate Ifng expression may have increased MS risk despite high ambient UV irradiation because of low Vdr gene expression and a high encephalitogenic T cell burden in the CNS.

Interleukins, from 1 to 37, and interferon-γ: receptors, functions, and roles in diseases

Advancing our understanding of mechanisms of immune regulation in allergy, asthma, autoimmune diseases, tumor development, organ transplantation, and chronic infections could lead to effective and targeted therapies. Subsets of immune and inflammatory cells interact via ILs and IFNs; reciprocal regulation and counter balance among T(h) and regulatory T cells, as well as subsets of B cells, offer opportunities for immune interventions. Here, we review current knowledge about ILs 1 to 37 and IFN-γ. Our understanding of the effects of ILs has greatly increased since the discoveries of monocyte IL (called IL-1) and lymphocyte IL (called IL-2); more than 40 cytokines are now designated as ILs. Studies of transgenic or knockout mice with altered expression of these cytokines or their receptors and analyses of mutations and polymorphisms in human genes that encode these products have provided important information about IL and IFN functions. We discuss their signaling pathways, cellular sources, targets, roles in immune regulation and cellular networks, roles in allergy and asthma, and roles in defense against infections.

Polymorphisms of innate pattern recognition receptors, response to interferon-beta and development of neutralizing antibodies in multiple sclerosis patients

BACKGROUND

Interferon-beta therapy of patients with relapsing-remitting multiple sclerosis involves repeated 'immunizations' with exogenous protein solutions. Innate pattern recognition receptors play an important role in immune responses towards foreign substances and may thus be related to treatment outcome.

OBJECTIVE

To determine the genotypes at 42 single nucleotide polymorphism loci in selected pattern recognition receptors for 567 prospectively followed relapsing-remitting multiple sclerosis patients treated with recombinant interferon-beta, and test for relationships to several outcome parameters, including formation of interferon-beta neutralizing antibodies.

RESULTS

The results suggest an association between the rs5743810 polymorphism (Ser249Pro) of TLR6 and development of neutralizing antibodies after 24 months of therapy in males (p = 0.00002), but not in females (p = 0.2). This association survived crude Bonferroni correction (p (corrected) = 0.02). Additional associations were observed in carriers of the TLR2-rs5743708 and NOD2-rs3135499 SNPs (time to relapse), the TLR7-rs179008 and NOD1-rs2075820 SNPs (time to disease progression) and the TLR4-rs7873784, TLR9-rs5743836, and NOD2-rs2066842 SNPs (frequency of neutralizing antibodies development). All of these, however, failed to survive correction for multiple testing. There were no significant differences between interferon-beta responders and non-responders for any of the investigated single nucleotide polymorphisms.

CONCLUSIONS

The rs5743810 polymorphism of TLR6 may be involved in development of anti-interferon-beta antibodies in males, although further studies are required to firmly establish this.

Multiparametric analysis of cytokine-driven human Th17 differentiation reveals a differential regulation of IL-17 and IL-22 production

T helper 17 (Th17) cells produce IL-17 but can also make tumor necrosis factor, interleukin (IL)-6, IL-10, IL-21, and IL-22. These cytokines collectively contribute to the functional outcome of the Th response. IL-22 plays a critical role in some Th17-associated diseases, such as psoriasis, but its relationship to IL-17 remains controversial. Here, we used a systematic multiparametric analysis of Th-17-associated cytokines, which revealed the unexpected finding that the regulation pattern of IL-22 was most closely related to interferon-gamma, the prototypical Th1 cytokine, and not to IL-17. To explain this observation, we systematically tested the role of Th1- and Th17-inducing cytokines. We could show that IL-12 and IL-23 induced high levels of IL-22 but no IL-17. Conversely, transforming growth factor-beta inhibited IL-22 production but promoted IL-17. Thus, IL-17 and IL-22 are differentially regulated during cytokine-induced Th cell differentiation. This has important implications for the understanding and pharmacologic manipulation of Th17-associated pathologies.

IL-22 is expressed by Th17 cells in an IL-23-dependent fashion, but not required for the development of autoimmune encephalomyelitis

Lately, IL-17-secreting Th cells have received an overwhelming amount of attention and are now widely held to be the major pathogenic population in autoimmune diseases. In particular, IL-22-secreting Th17 cells were shown to specifically mark the highly pathogenic population of self-reactive T cells in experimental autoimmune encephalomyelitis (EAE). As IL-17A itself was found to only play a minor role during the development of EAE, IL-22 is now postulated to contribute to the pathogenic function of Th17 cells. The goal of this study was to determine the role and function of IL-22 during the development of CNS autoimmunity in vivo. We found that CNS-invading encephalitogenic Th17 cells coexpress IL-22 and that IL-22 is specifically induced by IL-23 in autoimmune-pathogenic CD4+ T cells in a time- and dose-dependent manner. We next generated IL-22-/- mice, which--in contrast to the prediction that expression of inflammatory cytokines by CNS-invading T cells inevitably confers pathogenic function--turned out to be fully susceptible to EAE. Taken together, we show that self-reactive Th cells coexpress IL-17 and IL-22, but that the latter also does not appear to be directly involved in autoimmune pathogenesis of the CNS.

The neuropeptide genes TAC1, TAC3, TAC4, VIP and PACAP(ADCYAP1), and susceptibility to multiple sclerosis

The related immunomodulatory neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylyl cyclase activating peptide (PACAP; gene symbol ADCYAP1) have recently been proposed as novel therapeutics for the treatment of multiple sclerosis (MS). These neuropeptides, as well as those belonging to the tachykinin family exert pleiotropic effects, many of which are of relevance to central nervous system inflammation. In the present study, we have analysed 14 single nucleotide polymorphisms (SNPs) and 4 microsatellite markers in the VIP, ADCYAP1, TAC3 and TAC4 genes for susceptibility to MS in a case-control collection from Northern Ireland. Following correction for multiple comparisons, we did not find any significant associations between single polymorphic markers or multiple-marker haplotypes and susceptibility to MS. Furthermore, we analysed 2 SNPs in the TAC1 gene in a set of Sardinian trio MS families, based on our previous observation of association of these SNPs with MS in the Northern Irish (Genes Immun. 2005, 6, 265-270). Analysis of these SNPs in the Sardinians was not significant though a similar trend to that originally observed in the Northern Irish was present. Meta-analysis of the Sardinian and Northern Irish TAC1 SNP genotype data revealed a Mantel-Haenszel Common OR Estimate for the TAC1 intron 1 SNP rs2072100 of 0.76 (95% CI 0.63-0.92; P=0.005; A allele) and for the TAC1 promoter SNP rs7793277 of 0.76 (95% CI 0.615-0.95; P=0.014; C allele). Our data advocate a need for further exploration of the TAC1 gene region in MS.

Polymorphisms in the interleukin-4 and IL-4 receptor genes modify risk for chronic inflammatory arthropathies in women

Rheumatoid and juvenile idiopathic arthritis (RA, JIA) are chronic inflammatory arthropathies with polygenic autoimmune background. We analysed the IL-4 +33 C/T and IL-4R Q551R single nucleotide polymorphisms (SNPs) in 294 RA, 72 JIA and 165 controls from Northern Ireland. Analysis of the individual phenotypes (RA or JIA) showed that both the IL-4 +33 TT (P = 0.02; OR: 0.25, 95% CI: 0.07-0.87) and the IL-4R Q551R CC genotypes (P = 0.001; OR: 0.19, 95% CI: 0.06-0.56) were exclusively decreased in female RA patients compared to female controls. Similar non-significant trends were observed in female JIA patients (OR: 0.25, 95% CI: 0.03-2.11 and OR: 0.31, 95% CI: 0.07-1.47, respectively). Analysis of the common phenotype (inflammatory arthropathy; i.e. JIA and RA combined) corroborated the unique association of these polymorphisms with female inflammatory arthropathy (P = 0.013 and 0.002, respectively). This is the first demonstration of sex-specific association of the two foremost genes of the IL-4 signalling cascade with chronic inflammatory arthropathies.

Epidemiology and natural history of multiple sclerosis: new insights

PURPOSE OF REVIEW

The cause of multiple sclerosis remains elusive. We review recent epidemiological studies of genetic and environmental factors that influence susceptibility to the disease and its clinical course.

RECENT FINDINGS

Genetic advances strengthen the association of multiple sclerosis with the human leukocyte antigen (HLA)-DRB1 allele and interferon-gamma polymorphisms and suggest that apolipoprotein E alleles play an important role. In the environmental realm, nested case-control studies show that prior Epstein-Barr virus exposure is overrepresented in multiple sclerosis. Smoking has been associated with both risk of multiple sclerosis and progressive disease. Vitamin D deficiency might tie together environmental clues with higher multiple sclerosis prevalence rates; dietary vitamin supplementation is also associated with reduced multiple sclerosis risk. Natural history studies demonstrated dissociation between relapses and disease progression, facilitated the ability to distinguish neuromyelitis optica and related syndromes from typical multiple sclerosis, and spawned the exploration of large datasets to model long-term disease activity.

SUMMARY

Our understanding of the contributions of specific genetic and environmental factors that contribute to multiple sclerosis has improved. Further refinements will eventually allow powerful longitudinal studies to assess genetic and environmental interactions with implications for prediction of individual disease susceptibility, clinical course, and response to therapy.

Sex hormones: a role in the control of multiple sclerosis?

Several lines of evidence suggest that gender affects the susceptibility and course of multiple sclerosis. A higher disease prevalence, as well as an overall better prognosis, in women than men is observed. This sex dimorphism may be explained by the effect of sex hormones on brain damage and repair mechanisms. Experimental, clinical and MRI evidence confirms a pathogenetic link between sex hormones and multiple sclerosis, also suggesting sex-specific effects of hormones in multiple sclerosis pathology and therapy. A gender-based approach to multiple sclerosis could provide further benefits for its treatment and management.

Interleukin-22 and its crystal structure

Interleukin-22 (IL-22) is a cytokine that regulates the production of acute phase proteins of the immunological response. On binding to its cognate receptor (IL-22R1), which is associated to the interleukin-10 receptor 2 (IL-10R2), IL-22 promotes activation of signal transducer and activator of transcription (STAT) pathway and several other cellular responses. A soluble receptor termed interleukin-22 binding protein (IL-22BP) is also able to bind to IL-22 as a natural protein antagonist, and probably provides systemic regulation of IL-22 activity. This inflammatory response system is analyzed here in terms of its molecular physiology and structural assembly. Three-dimensional (3D) model of IL-22 and structural basis of its interactions with the cognate receptors are discussed.

Th1 Cytokine Polymorphisms in Spanish Patients With Type 1 Diabetes

Several polymorphisms in regions where Th1 cytokines (IL12B and IFNG genes) are located were analyzed in 303 Spanish subjects with type 1 diabetes and compared with a control cohort (n = 548). Both groups comprised residents of the Madrid area. The haplotype frequencies were estimated by the expectation-maximization algorithm, and p values were corrected by the number of haplotypes taken into account in the study. Two haplotypes were significantly associated with the disease, one in the IL12B region (D5S2038*8/D5S1352*2/SNP1188C; OR = 3.01, p(c) = 0.0255) and another involved the IFNGgene (D12S313*9/IFNG*1; OR = 1.58, p(c) = 0.0217). Furthermore, a protective IL12B haplotype was found (D5S2038*4/D5S1352*1/SNP1188A; OR = 0.40, p(c) = 0.0405). No association was found for any of IL12B and IFNG markers individually.

IFNG polymorphisms are associated with gender differences in susceptibility to multiple sclerosis

Interferon-gamma (IFNgamma) treatment is deleterious in multiple sclerosis (MS). MS occurs twice as frequently in women as in men. IFNgamma expression varies by gender. We studied a population-based sample of US MS patients and ethnicity-matched controls and independent Northern Irish and Belgian hospital-based patients and controls for association with MS, stratified by gender, of an intron 1 microsatellite [I1(761)*CAn], a single nucleotide polymorphism 3' of IFNG [3'(325)*G --> A] and three flanking microsatellite markers spanning a 118 kb region around IFNG. Men carriers of the 3'(325)*A allele have increased susceptibility to MS compared to noncarriers in the USA (P=0.044; OR: 2.58, 95% CI: 0.97-8.08) and Northern Ireland (P=0.019; OR: 2.37, 95% CI: 1.10-5.13). There is a nonsignificant trend in the same direction in Belgian men (P=0.299; OR: 1.50, 95% CI: 0.71-3.26). Men carriers of I1(761)*CA13, which is in strong linkage disequilibrium with the 3'(325)*A, have increased susceptibility (P=0.050; OR: 2.22, 95% CI: 0.98-5.40), while men carriers of I1(761)*CA12 have decreased susceptibility (P=0.022; OR: 0.46, 95% CI: 0.23-0.90) to MS in the USA. Similar associations were reported in Sardinia between the I1(761)*CA12 allele and reduced risk of MS in men. Flanking markers were not associated with MS susceptibility. Polymorphisms of IFNG may contribute to differences in susceptibility to MS between men and women.

The T-cell lymphokine interleukin-26 targets epithelial cells through the interleukin-20 receptor 1 and interleukin-10 receptor 2 chains

The cellular members of the interleukin-10 (IL-10) cytokine family share sequence homology with IL-10, whereas their sites of expression and their functions are divergent. One of these factors, AK155 or IL-26, was discovered because of its overexpression in human T lymphocytes after growth transformation by the simian rhadinovirus herpesvirus saimiri. In addition, the gene is transcribed in various types of primary and immortalized T-cells. Here we describe epithelial cells, namely colon carcinoma cells and keratinocytes, as targets of this T-cellular lymphokine. Purified recombinant IL-26 induced the rapid phosphorylation of the signal transducer and activator of transcription factors 1 and 3. As a result, secretion of IL-10 and IL-8, as well as cell surface expression of CD54 were enhanced. Moreover, we show that the IL-26 protein binds to heparin, is released from the cell surface, and can be functionally inhibited by heparin. The sensitivity to recombinant IL-26 of various cell lines strictly correlated with the expression of the long chain of the IL-20 receptor. Because blocking antibodies against either the short chain of the IL-10 receptor or the long chain of the IL-20 receptor inhibited IL-26-dependent signal transduction, and transient expression of these receptor chains induced IL-26 responsivity in non-sensitive cells, we propose that the IL-20 receptor 1 and IL-10 receptor 2 chains participate in forming the IL-26 receptor. Targeting epithelial cells, the T-cell lymphokine IL-26 is likely to play a role in local mechanisms of mucosal and cutaneous immunity.

Interleukin-26

Interleukin-26 (IL-26), initially termed AK155, is a cellular sequence homolog to IL-10 belonging to the IL-10 cytokine family. Together with the related genes for interferon-gamma and IL-22/IL-TIF, il-26 maps to the human chromosomal region 12q15. The il-26 gene is one of the few differentially expressed genes specifying human T cells after growth-transformation with herpesvirus saimiri, a tumor virus of neo-tropical squirrel monkeys. Only herpesvirus saimiri-transformed T cells have been found to strongly over-express il-26 and to release the protein into the tissue culture supernatant. In a series of other T-cell lines and in native peripheral blood cells, il-26 is transcribed at low levels, but it is not detectable in B cells. Similarly to IL-10, the IL-26 protein forms homo-dimers. IL-26 is a candidate to contribute to the transformed phenotype of human T cells after infection by herpesvirus saimiri. Moreover, the T-lymphokine IL-26 is highly likely to play a role in normal and pathological hematology or immunology.

Polymorphisms in the interferon-γ/interleukin-26 gene region contribute to sex bias in susceptibility to rheumatoid arthritis

OBJECTIVE

To determine whether polymorphisms in the interferon-gamma (IFNgamma)/interleukin-26 (IL-26; formerly, AK155) gene cluster contribute to sex-based differential susceptibility to rheumatoid arthritis (RA).

METHODS

Four microsatellite markers, located in a 118-kb interval that contains both the IFNgamma and IL-26 genes on chromosome 12q15, were typed in 251 patients with RA and 198 unrelated healthy controls (all of whom lived in Northern Ireland) by means of polymerase chain reaction-based fragment analysis.

RESULTS

Marker D12S2510, which is located 3 kb 3' from the IL-26 gene, was significantly associated with RA in women (corrected P [P(corr)] = 0.008, 2 degrees of freedom [2 df]) but not in men (P = 0.99, 2 df). A 3-marker haplotype, IFNGCA*13;D12S2510*8;D12S2511*9, was inferred that showed significant underrepresentation in women with RA (odds ratio 0.50, 95% confidence interval 0.32-0.78; P = 0.002, P(corr) = 0.03) but not in men with RA.

CONCLUSION

Our results demonstrate that common polymorphisms in the IFNgamma/IL-26 gene region may contribute to sex bias in susceptibility to RA, by distorting the propensity of female carriers versus male carriers to contract this disease. These results conform to our recent observations of a role for this gene cluster in sex-based differential susceptibility to another Th1-type inflammatory disease, multiple sclerosis.

A genome-wide screen for linkage disequilibrium in Australian HLA-DRB1*1501 positive multiple sclerosis patients

The association of multiple sclerosis with alleles/haplotypes from the HLA region on chromosome 6p21 is well established although the remainder of the genome remains relatively unexplored. We have completed a genome-wide screen for linkage disequilibrium in a cohort of Australian multiple sclerosis patients positive for HLA-DRB1*1501. A total of 4346 microsatellite markers provided through the "Genetic Analysis of Multiple sclerosis in EuropeanS" (GAMES) collaborative were analysed in DNA separately pooled from cases (n=217) and controls (n=187). Associations were found in four genomic regions (12q15, 16p13, 18p11 and 19q13) previously identified in linkage genome screens. Three additional regions of novel association were also identified (11q12, 11q23 and 14q21). Further analysis of these regions is required to establish whether the associations observed are due to epistatic interaction with the HLA locus.

Cytokine gene polymorphisms in multifactorial diseases: gateways to novel targets for immunotherapy?

Recent advances in cytokine biology have led to novel approaches to the treatment of inflammatory diseases. In this article, we review recent data regarding the role of functional polymorphisms in the genes encoding the prototypic Th1 cytokine interferon gamma and Th2 cytokine interleukin 4 in multifactorial disorders. We have compared genetic data across a heterogeneous assortment of such conditions using a 'haplotype tagging' approach, and demonstrate that cytokine gene association studies are instrumental in the identification of specific disease states or clinical manifestations that are probably caused by genetically determined aberrant cytokine expression. Some of these new findings suggest cytokine effects that go beyond a classical Th1-Th2 dichotomy. Thus, we propose that this information could provide novel targets for immunotherapy and, in particular, might facilitate the identification of clinical subgroups of patients who, by virtue of their genetic constitution at these cytokine gene loci, are more likely to benefit from cytokine agonist or antagonist therapy.