STAT3 locus in inflammatory bowel disease and multiple sclerosis susceptibility

Diverse signaling mechanisms and heterogeneity of astrocyte reactivity in Alzheimer's disease

Alzheimer's disease (AD) affects various brain cell types, including astrocytes, which are the most abundant cell types in the central nervous system (CNS). Astrocytes not only provide homeostatic support to neurons but also actively regulate synaptic signaling and functions and become reactive in response to CNS insults through diverse signaling pathways including the JAK/STAT, NF-κB, and GPCR-elicited pathways. The advent of new technology for transcriptomic profiling at the single-cell level has led to increasing recognition of the highly versatile nature of reactive astrocytes and the context-dependent specificity of astrocyte reactivity. In AD, reactive astrocytes have long been observed in senile plaques and have recently been suggested to play a role in AD pathogenesis and progression. However, the precise contributions of reactive astrocytes to AD remain elusive, and targeting this complex cell population for AD treatment poses significant challenges. In this review, we summarize the current understanding of astrocyte reactivity and its role in AD, with a particular focus on the signaling pathways that promote astrocyte reactivity and the heterogeneity of reactive astrocytes. Furthermore, we explore potential implications for the development of therapeutics for AD. Our objective is to shed light on the complex involvement of astrocytes in AD and offer insights into potential therapeutic targets and strategies for treating and managing this devastating neurodegenerative disorder.

[Molecular Mechanism-based Prediction of Interstitial Lung Disease Development Causedby Molecular Targeted Drugs: Association between Signal Transducer and Activator of Transcription 3 and Mammalian Target of Rapamycin inhibitor-induced Interstitial Lung Disease]

Interstitial lung disease (ILD) is a serious adverse event common to many molecular targeted anticancer drugs. The development of ILD significantly reduces the QOL of patients and results in treatment discontinuation. Because the development of ILD is also associated with therapeutic efficacy, the establishment of prediction strategies for ILD is important. We have focused on signal transducer and activator of transcription 3 (STAT3) as an important mechanistic factor in ILD induced by molecular targeted drugs. Our study aimed to establish mechanism-based ILD prediction strategies; therefore, we investigated the hypothesis that a genetic polymorphism in STAT3 is a predictive factor of the incidence of ILD induced by mammalian target of rapamycin (mTOR) inhibitors, a class of molecular targeted drugs associated with a higher incidence of ILD. Our clinical study clearly demonstrated that the rate of ILD induced by mTOR inhibitors was significantly higher in patients with the G allele homozygous genotype of STAT3 -1697C>G compared with those with other genotypes. The cumulative incidence of ILD in patients with the G allele homozygous genotype was significantly higher compared with that in patients carrying other genotypes. Furthermore, our in vitro study indicated that the epithelial-to-mesenchymal transition (EMT), a pre-process of tissue fibrosis, was induced by an mTOR inhibitor in lung alveolar epithelial cell lines carrying the G allele homozygous genotype which was associated with a higher risk of ILD. Our study provided a novel predictive strategy for the development of ILD induced by molecular targeted drugs.

STAT3 gain-of-function is not responsible for low total IgE levels in patients with autoimmune chronic spontaneous urticaria

Background

The pathogenesis of chronic spontaneous urticaria (CSU) has not been clarified entirely. Type IIb autoimmune chronic spontaneous urticaria (CSUaiTIIb) is a distinct subtype of CSU that is often difficult to treat and is connected to low levels of total IgE. Previous findings indicate that an enhanced signal transducer and activator of transcription 3 (STAT3) may be responsible for reduced IgE serum levels.

Objective

Our aim was to investigate a possible underlying gain-of-function mutation or activating polymorphism in STAT3 that could be responsible for the low levels of IgE in patients with CSUaiTIIb.

Methods

We included 10 patients with CSUaiTIIb and low levels of IgE and sequenced selected single nucleotide polymorphisms (SNP) in STAT3 associated with common autoimmune diseases. Exon sequencing was performed for the most relevant exons of STAT3. To test for a gain-of-function of STAT3, we performed a phospho-specific flow cytometry analysis of STAT3 in peripheral blood mononuclear cells before and after stimulation with interleukin-6.

Results

No differences were found in the prevalence of the tested SNPs between our patients and a control population. Moreover, we could not find any mutations or variants on the tested exons of STAT3. The function of STAT3 was also not altered in our patients.

Conclusion

In total, we could not find any evidence for our hypothesis that low IgE in patients with CSUaiTIIb is linked to mutations in STAT3 or altered activity of STAT3. Thus, it remains to be discovered what causes the low serum levels of IgE in patients with CSUaiTIIb.

Activation pathways that drive CD4+ T cells to break tolerance in autoimmune diseases. Immunol Rev 2022;307:161-190. [PMID: 35142369 PMCID: PMC9255211 DOI: 10.1111/imr.13071]

Autoimmune diseases are characterized by dysfunctional immune systems that misrecognize self as non-self and cause tissue destruction. Several cell types have been implicated in triggering and sustaining disease. Due to a strong association of major histocompatibility complex II (MHC-II) proteins with various autoimmune diseases, CD4+ T lymphocytes have been thoroughly investigated for their roles in dictating disease course. CD4+ T cell activation is a coordinated process that requires three distinct signals: Signal 1, which is mediated by antigen recognition on MHC-II molecules; Signal 2, which boosts signal 1 in a costimulatory manner; and Signal 3, which helps to differentiate the activated cells into functionally relevant subsets. These signals are disrupted during autoimmunity and prompt CD4+ T cells to break tolerance. Herein, we review our current understanding of how each of the three signals plays a role in three different autoimmune diseases and highlight the genetic polymorphisms that predispose individuals to autoimmunity. We also discuss the drawbacks of existing therapies and how they can be addressed to achieve lasting tolerance in patients.

Upregulation of signal transducer and activator of transcription 3 in dogs with chronic inflammatory enteropathies

Background

In inflammatory bowel disease (IBD) in humans, phosphorylated signal transducer and activator of transcription 3 (pSTAT3) is upregulated in mucosal epithelial cells and correlates with clinical severity.

Hypothesis/Objective

To investigate the expression pattern of pSTAT3 in the mucosa of dogs with chronic inflammatory enteropathy (CIE) and explore correlations between its expression and clinical and histopathological severity scoring.

Animals

Twenty‐eight canine CIE patients grouped into food‐responsive enteropathy (FRE;  9), steroid‐responsive enteropathy (SRE;  10), and protein‐losing enteropathy (PLE;  9). Ten healthy beagle dogs served as controls (CO).

Methods

Retrospective case control study. Immunohistochemistry was used to detect pSTAT3 in canine duodenal mucosa samples.

Results

Compared to CO, SRE (P < .001) and PLE (P < .001) dogs had significantly higher pSTAT3 expression in the villus epithelium. The SRE group had a significantly higher expression in the villus lamina propria (VLP) compared to controls (P = .009). In the crypt epithelium (CE), all CIE dogs had significantly higher pSTAT3 expression (FRE, P = .002; SRE, P = .003; PLE, P < .001) compared to CO. In the lamina propria crypt region (CLP), dogs with FRE (P = .04) and SRE (P = .03) had significantly upregulated pSTAT3 compared to controls. A positive correlation was found between canine chronic enteropathy clinical activity index (CCECAI) scoring and pSTAT3 expression for both epithelial (rho = .541; P < .001) and crypt regions (rho = .32; P = .02).

Conclusions and Clinical Importance

pSTAT3 is upregulated in CIE in dogs, correlates with clinical severity, and may be helpful as a clinical marker in dogs with CIE.

Epigenetic mechanisms shape the underlining expression regulatory mechanisms of the STAT3 in multiple sclerosis disease

Objectives

Immunological tolerance is mediated by CD4⁺CD25⁺ regulatory T (Treg) cells. Studies have shown that thymic and peripheral generations of Treg cells depend on the CD28 signaling pathway. T helper 17 (Th17) cells are involved in the pathophysiology of various inflammatory diseases. Cytokines, such as interleukin (IL)-6 and TGF-β, regulate the reciprocal development of Th17 and Treg cells. In CD4⁺ T cells, signal transducer and activator of transcription 3 (STAT3) play a critical role in the induction of Th17 cell differentiation and inhibition of Treg cell development.

Results

In this study, we investigated the STAT3 methylation and gene expression status in patients with MS. Our study demonstrated that the level of STAT3 methylation decreased in relapsing–remitting MS patient compared to control groups, which the decreases were statistically significant. STAT3 gene expression increased in patient group relative to healthy one, and the increases were found to be statistically significant. According to our findings, it can be suggested that DNA hypermethylation of STAT3 affects the gene expression. In addition, there is a strong and significant negative correlation between the methylation status and mRNA level of STAT3.

Mesenchymal stem cells and acellular products attenuate murine induced colitis

Background

Mesenchymal stem cells (MSCs) are a well-established immunomodulatory agent which can also promote tissue repair and regeneration. Recent studies have demonstrated MSCs as a novel therapeutic for inflammatory bowel disease (IBD), a chronic idiopathic inflammatory disorder of the gastrointestinal tract. However, the precise role of MSCs in regulating immune responses is controversial, and its significance in the pathogenesis remains IBD undefined. In addition, MSCs’ acellular product, extracellular vesicles (EVs), may also play an important role in the armamentarium of therapeutics, but how EVs compare to MSCs remains unknown due to the lack of side-by-side comparative investigation. We herein compared MSCs and MSC-derived EVs for the treatment of IBD using a DSS-induced colitis model.

Methods

A DSS-induced colitis model was used. At day 4, mice received adipose-derived MSCs, MSC-derived EVs, or placebo. Weight loss, stool consistency, and hematochezia was charted. At day 8, murine colons were harvested, histologic analysis performed, and serum/tissue cytokine analysis conducted.

Results

MSCs and EVs demonstrated equivalent immunosuppressive function in DSS-treated mice through decreased colonic lymphocyte infiltration and attenuated disease severity after both MSC and EV treatment. Furthermore, both MSCs and EVs have an equivalent ability to inhibit inflammation in the DSS colitis model by inhibiting JAK, JNK 1/2, and STAT3 signaling.

Conclusions

These results suggest that (i) both MSCs and EVs are effective therapeutic candidates for a DSS-induced mouse colitis model, (ii) MSCs and EVs have similar immunosuppressive and anti-inflammatory functions, and (iii) EVs may present a novel future therapeutic for the treatment of IBD.

MicroRNA124-IL6R Mediates the Effect of Nicotine in Inflammatory Bowel Disease by Shifting Th1/Th2 Balance Toward Th1

Epidemiological investigations have shown that smoking ameliorates ulcerative colitis (UC) but exacerbates Crohn's disease (CD), diseases that feature a Th2-mediated and Th1-mediated response, respectively. Cigarette extracts, especially nicotine, affect the Th1/Th2 balance. We previously reported that nicotine protects against mouse DSS colitis (similar to UC) by enhancing microRNA-124 (miR-124) expression. Intriguingly, elevation of miR-124 in CD is reported to aggravate the disease. Here we investigate the dual regulation of miR-124 in inflammatory bowel diseases (IBDs), which may explain the similar bidirectional regulation of tobacco. We found that overexpressed miR-124 protected against mouse DSS-induced colitis with a Th1 polarization in peripheral blood lymphocytes and colon tissues, which was also found in human peripheral blood lymphocytes. Conversely, miR-124 knockdown worsened DSS murine colitis with a Th2 polarization. Moreover, knockdown of miR-124 could eliminate the polarization toward Th1 after nicotine treatment, suggesting that miR-124 mediates the effect of nicotine on the Th1/Th2 balance. In addition, interference of IL-6R, which is a downstream target of miR-124, could remarkably weaken the Th1 polarization induced by miR-124. Taken together, these results suggest that nicotine shifts the balance of Th1/Th2 toward Th1 via a miR-124-mediated IL-6R pathway, which might explain its dual role in IBDs.

Utilization of albumin fraction from defatted rice bran to stabilize and deliver (-)-epigallocatechin gallate

This work aims to use defatted rice bran albumin (RBA) for delivering epigallocatechin gallate (EGCg). The mode of RBA particle size shifted from 142 nm to 164 nm upon interaction with EGCg. Hydrophobic interaction is the major force between EGCg and RBA resulted in the formation of EGCg-RBA complex based on fluorescence quenching. Upon incorporation into RBA, the recovery of EGCg in pH 7.4 phosphate buffer was elevated by 2 folds. The recovery of EGCg in EGCg-RBA was 18.9% after 2 h intestinal digestion, being higher than 7.6% of native EGCg. The pretreatments of HT-29 cells with EGCg, RBA and EGCg-RBA significantly repressed the transcriptional activation of mitogen-activated protein kinase 14, nuclear transcription factor-κB, and activators of transcription 3 as stimulated with interleukin-1β afterwards, leading to attenuated expressions of corresponding downstream genes. Antioxidant ability importantly functioned in anti-inflammation. RBA is a promising vehicle with inherent anti-inflammatory property for stabilizing and delivering EGCg.

IL-21 Controls ILC3 Cytokine Production and Promotes a Protective Phenotype in a Mouse Model of Colitis

Group 3 innate lymphoid cells (ILC3s) have dual roles in intestinal health, acting in both protective and pathogenic capacities, and importantly, modulations in this population of innate lymphoid cells have been implicated in inflammatory bowel disease. Further, subpopulations of ILC3s have been described as serving specific functions in maintaining homeostasis or responding to infection, and aberrant activation of one or more of these subpopulations could exacerbate inflammatory bowel disease. However, the signals that enforce the protective and pathogenic features of ILC3s are not fully elucidated. In this article, we show that IL-21, a cytokine primarily produced by CD4 T cells, acts on a subpopulation of intestinal ILC3s to promote a protective phenotype. IL-21 signaling does not affect the MHC class II-expressing ILC3 subset but promotes ILC3s that express Tbet and are poised to produce IL-22. Consistent with a protective phenotype, IL-21 deficiency dampens cytokine-induced IL-17A production. We show that exacerbated colitis develops in mice lacking the IL-21 receptor, in agreement with a protective role for IL-21 signaling on ILC3s. To our knowledge, these data reveal a novel role for IL-21 in shaping innate lymphoid cell responses in the intestine and provide one mechanism by which effector CD4 T cells can influence innate immunity.

Deficiency of Socs3 leads to brain-targeted EAE via enhanced neutrophil activation and ROS production

Dysregulation of the JAK/STAT signaling pathway is associated with Multiple Sclerosis (MS) and its mouse model, Experimental Autoimmune Encephalomyelitis (EAE). Suppressors Of Cytokine Signaling (SOCS) negatively regulate the JAK/STAT pathway. We previously reported a severe, brain-targeted, atypical form of EAE in mice lacking Socs3 in myeloid cells (Socs3ΔLysM), which is associated with cerebellar neutrophil infiltration. There is emerging evidence that neutrophils are detrimental in the pathology of MS/EAE, however, their exact function is unclear. Here we demonstrate that neutrophils from the cerebellum of Socs3ΔLysM mice show a hyper-activated phenotype with excessive production of reactive oxygen species (ROS) at the peak of EAE. Neutralization of ROS in vivo delayed the onset and reduced severity of atypical EAE. Mechanistically, Socs3-deficient neutrophils exhibit enhanced STAT3 activation, a hyper-activated phenotype in response to G-CSF, and upon G-CSF priming, increased ROS production. Neutralization of G-CSF in vivo significantly reduced the incidence and severity of the atypical EAE phenotype. Overall, our work elucidates that hypersensitivity of G-CSF/STAT3 signaling in Socs3ΔLysM mice leads to atypical EAE by enhanced neutrophil activation and increased oxidative stress, which may explain the detrimental role of G-CSF in MS patients.

Protein Tyrosine Phosphatases: Regulators of CD4 T Cells in Inflammatory Bowel Disease

Protein tyrosine phosphatases (PTPs) play a critical role in co-ordinating the signaling networks that maintain lymphocyte homeostasis and direct lymphocyte activation. By dephosphorylating tyrosine residues, PTPs have been shown to modulate enzyme activity and both mediate and disrupt protein-protein interactions. Through these molecular mechanisms, PTPs ultimately impact lymphocyte responses to environmental cues such as inflammatory cytokines and chemokines, as well as antigenic stimulation. Mouse models of acute and chronic intestinal inflammation have been shown to be exacerbated in the absence of PTPs such as PTPN2 and PTPN22. This increase in disease severity is due in part to hyper-activation of lymphocytes in the absence of PTP activity. In accordance, human PTPs have been linked to intestinal inflammation. Genome wide association studies (GWAS) identified several PTPs within risk loci for inflammatory bowel disease (IBD). Therapeutically targeting PTP substrates and their associated signaling pathways, such as those implicated in CD4⁺ T cell responses, has demonstrated clinical efficacy. The current review focuses on the role of PTPs in controlling CD4⁺ T cell activity in the intestinal mucosa and how disruption of PTP activity in CD4⁺ T cells can contribute to intestinal inflammation.

Effector T Helper Cell Subsets in Inflammatory Bowel Diseases

The gastrointestinal tract is a site of high immune challenge, as it must maintain a delicate balance between tolerating luminal contents and generating an immune response toward pathogens. CD4⁺ T cells are key in mediating the host protective and homeostatic responses. Yet, CD4⁺ T cells are also known to be the main drivers of inflammatory bowel disease (IBD) when this balance is perturbed. Many subsets of CD4⁺ T cells have been identified as players in perpetuating chronic intestinal inflammation. Over the last few decades, understanding of how each subset of Th cells plays a role has dramatically increased. Simultaneously, this has allowed development of therapeutic innovation targeting specific molecules rather than broad immunosuppressive agents. Here, we review the emerging evidence of how each subset functions in promoting and sustaining the chronic inflammation that characterizes IBD.

Lack of significant association between selected STAT3 polymorphisms and rheumatoid arthritis in the Polish population

OBJECTIVES

Rheumatoid arthritis (RA) is the most common systemic inflammatory disease and is of unknown etiology. The altered balance between immunosuppressive and inflammatory T cell subpopulations exerts a huge impact on RA pathogenesis. The STAT3 protein regulates genes involved in the immune responses. It regulates maturation of T and B cells. Its abnormal activity is significantly associated with autoimmune diseases and cancer development. We aimed to evaluate the contribution of three potentially functional single nucleotide polymorphisms (SNPs) within the STAT3 gene to susceptibility and severity of RA in the Polish population.

MATERIAL AND METHODS

A total of 595 patients with RA and 330 healthy individuals were included in the study. DNA from patients and healthy subjects was obtained from peripheral blood using standard DNA isolating methods. The STAT3 rs1053005, rs1026916 and rs2293152 polymorphisms were genotyped using the TaqMan SNP genotyping assay. The accuracy of SNP genotyping was confirmed using direct DNA sequence analysis.

RESULTS

The distribution of STAT3 polymorphisms did not differ significantly between cases and controls. Our results revealed a tendency only, where rs1026916 AA genotype occurred more frequently in RA patients compared to healthy controls, in codominant (p = 0.09), dominant (p = 0.06) and recessive (p = 0.09) models. STAT3 rs2293152 polymorphism was associated with higher DAS28 (p = 0.014 codominant model; p = 0.003 dominant model), increased number of swollen joints (p = 0.02), higher VAS (p = 0.01) and higher HAQ score (p = 0.05).

CONCLUSIONS

We did not observe a significant association between the three studied STAT3 genetic variants and increased susceptibility to or severity of RA. Only the STAT3 rs2293152 polymorphism was associated with parameters that indicate a more severe course of the disease. However, its distribution did not differ between RA and control groups. According to our observations these 3 studied STAT3 SNPs may not be used as risk factors for developing RA.

Absence of specific alternatively spliced exon of CD44 in macrophages prevents colitis

CD44 is a transmembrane molecule appearing in numerous isoforms generated by insertions of alternatively spliced variant exons (CD44v) and having various binding partners. CD44v7 on T cells was proposed to promote colitis by preventing T-cell apoptosis. Here we demonstrate that Cd44v7-deficient T cells - like Cd44 wild-type (Cd44^WT) T cells - provoked disease in two different colitis models: the model induced by CD4⁺CD45RB^high T-cell transfer into Rag2-deficient mice and a new model based on ovalbumin (OVA)-specific T-cell transfer into Rag-sufficient, OVA-challenged mice. In contrast, CD44v7 absence on macrophages in recipient mice prevented colitis. Prevention was associated with the downregulation of signal transducer and activator of transcription 3 (STAT3)-activating and Foxp3-counteracting interleukin-6 (IL-6), lower numbers of phospho-STAT3-containing lymphocytes, and higher Foxp3⁺ T-cell counts in the colon. Consequently, the protected colons showed lower IL-12, IL-1β expression, and decreased interferon-γ levels. Importantly, stimulation of T cells by Cd44v7-deficient macrophages induced upregulation of Foxp3 in vitro, while cotransfer of Cd44^WT macrophages into Cd44v7-deficient mice reduced Foxp3⁺ T-cell counts and caused colitis. Accordingly, the CD44v7 ligand osteopontin, whose levels were elevated in Crohn's disease, specifically induced IL-6 in human monocytes, a cytokine also increased in these patients. We suggest macrophage-specific targeting of the CD44v7 pathway as a novel therapeutic option for Crohn's disease.

The Interleukin (IL)-23/T helper (Th)17 Axis in Experimental Autoimmune Encephalomyelitis and Multiple Sclerosis

T helper (Th)17 cells are responsible for host defense against fungi and certain extracellular bacteria but have also been reported to play a role in a variety of autoimmune diseases. Th17 cells respond to environmental cues, are very plastic, and might also be involved in tissue homeostasis and regeneration. The imprinting of pathogenic properties in Th17 cells in autoimmunity seems highly dependent on interleukin (IL)-23. Since Th17 cells were first described in experimental autoimmune encephalomyelitis, they have been suggested to also promote tissue damage in multiple sclerosis (MS). Indeed, some studies linked Th17 cells to disease severity in MS, and the efficacy of anti-IL-17A therapy in MS supported this idea. In this review, we will summarize molecular features of Th17 cells and discuss the evidence for their function in experimental models of autoimmune diseases and MS.

Molecular pathways driving disease-specific alterations of intestinal epithelial cells

Due to the fact that chronic inflammation as well as tumorigenesis in the gut is crucially impacted by the fate of intestinal epithelial cells, our article provides a comprehensive overview of the composition, function, regulation and homeostasis of the gut epithelium. In particular, we focus on those aspects which were found to be altered in the context of inflammatory bowel diseases or colorectal cancer and also discuss potential molecular targets for a disease-specific therapeutic intervention.

Meta-analysis of associations between DLG5 R30Q and P1371Q polymorphisms and susceptibility to inflammatory bowel disease

Growing evidence from recent studies has demonstrated an association between inflammatory bowel disease (IBD) susceptibility and two polymorphisms of DLG5 R30Q (rs1248696) and P1371Q (rs2289310), but the results remain controversial. We conducted a meta-analysis including a total of 22 studies with 10,878 IBD patients and 7917 healthy controls for R30Q and 5277 IBD cases and 4367 controls for P1371Q in order to systematically assess their association with the disease. The results indicated that R30Q was significantly associated with reduced susceptibility to IBD in Europeans by allelic and dominant comparisons, but not in overall population. No significant association was found between R30Q and Crohn's disease (CD) or ulcerative colitis (UC). P1371Q was associated with increased risk of IBD in Europeans and Americans. On the contrary, a decreased risk of IBD was observed in Asian population for P1371Q. In disease subgroup analysis, we found that P1371Q was also significantly associated with CD, but this relationship was not present for UC. In conclusion, our results strongly suggest that the both polymorphisms of DLG5 are correlated with IBD susceptibility in an ethnic-specific manner. Additional well-designed studies with large and diverse cohorts are needed to further strengthen our findings.

Grim19 Attenuates DSS Induced Colitis in an Animal Model

DSS induced colitis is a chronic inflammatory disease characterized by inflammation in the gastrointestinal tract, which destabilizes the gut and induces an uncontrolled immune response. Although DSS induced colitis is generally thought to develop as a result of an abnormally active intestinal immune system, its pathogenesis remains unclear. Gene associated with retinoid interferon induced mortality (Grim) 19 is an endogenous specific inhibitor of STAT3, which regulates the expression of proinflammatory cytokines. In this study, we investigated the influence of GRIM19 in a DSS induced colitis mouse model. We hypothesized that Grim19 would ameliorate DSS induced colitis by altering STAT3 activity and intestinal inflammation. Grim19 ameliorated DSS induced colitis severity and protected intestinal tissue. The expression of STAT3 and proinflammatory cytokines such as IL-1β and TNF-α in colon and lymph nodes was decreased significantly by Grim19. Moreover, DSS induced colitis progression in a Grim19 transgenic mouse line was inhibited in association with a reduction in STAT3 and IL-17 expression. These results suggest that Grim19 attenuates DSS induced colitis by suppressing the excessive inflammatory response mediated by STAT3 activation.

Immune deficiency vs. immune excess in inflammatory bowel diseases-STAT3 as a rheo-STAT of intestinal homeostasis

Genome-wide association studies have provided many genetic alterations, conferring susceptibility to multifactorial polygenic diseases, such as inflammatory bowel diseases. Yet, how specific genetic alterations functionally affect intestinal inflammation often remains elusive. It is noteworthy that a large overlap of genes involved in immune deficiencies with those conferring inflammatory bowel disease risk has been noted. This has provided new arguments for the debate on whether inflammatory bowel disease arises from either an excess or a deficiency in the immune system. In this review, we highlight the functional effect of an inflammatory bowel disease-risk allele, which cannot be deduced from genome-wide association studies data alone. As exemplified by the transcription factor signal transducer and activator of transcription 3 (STAT3), we show that a single gene can have a plethora of effects in various cell types of the gut. These effects may individually contribute to the restoration of intestinal homeostasis on the one hand or pave the way for excessive immunopathology on the other, as an inflammatory "rheo-STAT".

Single nucleotide polymorphisms in the STAT3 gene influence AITD susceptibility, thyroid autoantibody levels, and IL6 and IL17 secretion

STAT3 (signal transducer and activator of transcription 3) is an important cellular effector in the Jak/STAT signaling pathway, which plays a pivotal role in human immune system regulation, mediating the effect of different cytokines. In the present study, we assessed the correlation between STAT3 polymorphisms (rs3816769 C>T and rs744166 A>G) and risk of the autoimmune thyroid diseases (AITDs) Hashimoto’s thyroiditis (HT) and Graves’ disease (GD) in the Polish population. Moreover, we evaluated the association of polymorphisms with the thyroid autoantibody levels (TPOAb, TgAb, TRAb) and the correlation between circulating proinflammatory IL6 and IL17 cytokines and thyroid autoantibody levels. The study included 71 AITD patients with HT (n = 39) or GD (n = 32) and a control group (n = 40). DNA SNP genotyping was performed using TaqMan probes. Serum levels of thyroid autoantibodies, IL6 and IL17 were measured according to enhanced chemiluminescence (ECL) assay. Allele A of STAT3 SNP rs744166 A>G was significantly more frequent in both HT and GD patients, while allele G was significantly more frequent in the control group. Similarly, allele C and CC genotype of STAT3 SNP rs3816769 C>T were significantly more frequent in the control group in comparison to HT and GD patients. Significantly higher TgAb median values were associated with CT rs3816769 genotype in HT patients. Serum levels of IL6 and IL17 positively correlated with TPOAb in the HT group. Serum level of IL6 positively correlated with TPOAb in the AITD group. Both studied polymorphisms seem to play a significant role in susceptibility to AITD (HT and GD). STAT3 SNPs may influence TAb level in AITD patients.

Associations between STAT3 rs744166 polymorphisms and susceptibility to ulcerative colitis and Crohn's disease: a meta-analysis

BACKGROUND

Many studies have investigated the associations between the signal transducer and activator of transcription 3 (STAT3) in the susceptibility to ulcerative colitis (UC) and Crohn's disease (CD). However, the results remain inconsistent. This meta-analysis determined the risk of STAT3 rs744166 polymorphism-conferred UC and CD susceptibility.

MATERIALS AND METHODS

Electronic databases, including PubMed, EMBASE and the Cochrane Library, were searched for all eligible studies that evaluated the association between STAT3 rs744166 polymorphisms with UC and CD risk up to August 21, 2014. The pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using fixed- or random-effects models.

RESULTS

Twelve studies containing 10298 patients with CD, 4244 patients with UC and 11191 controls were included in this meta-analysis. The results indicated that the STAT3 rs744166 polymorphism was associated with CD and UC susceptibility (CD: GA+AA vs. GG, OR = 1.20, 95%CI, 1.11-1.30, I2 = 0%, Punadjusted<0.00001, PBonferroni<0.00005, PFDR<0.00001; UC: GA+AA vs. GG, OR = 1.21, 95%CI, 1.08-1.36, I2 = 1%, Punadjusted = 0.001, PBonferroni = 0.005, PFDR = 0.00125). In subgroup analyses by ethnicity, the significant association was found only among Caucasians. However, when grouped by age of onset, positive associations were found both among adults and children. In addition, when stratified by study design and genotyping methods, the risk of CD was significantly associated with the STAT3 rs744166 polymorphism in hospital-based and population-based groups and in SNP Array and SNPlex groups. For UC, significant associations were also found in population-based, PCR-RFLP and SNPlex groups. Moreover, these findings were sufficiently robust to withstand the Bonferroni correction and false discovery rate (FDR).

CONCLUSION

This meta-analysis indicates that carriers of the STAT3 rs744166 'A' allele have a significantly greater risk of CD and UC, especially among Caucasians.

An analysis of genetic factors related to risk of inflammatory bowel disease and colon cancer

BACKGROUND AND AIMS

Patients with inflammatory bowel disease (IBD) have a higher risk of developing colorectal cancer than the general population. Genome-wide association studies have identified and replicated several loci associated with risk of IBD; however, it is currently unknown whether these loci are also associated with colon cancer risk.

METHODS

We selected 15 validated SNPs associated with risk of either Crohn's disease, ulcerative colitis, or both in previous GWAS and tested whether these loci were also associated with colon cancer risk in a two-stage study design.

RESULTS

We found that rs744166 in STAT3 was associated with colon cancer risk in two studies; however, the direction of the observation was reversed in TP53 mutant tumors possibly due to a nullification of the effect by mutant p53. The SNP, which lies within intron 1 of the STAT3 gene, was associated with lower expression of STAT3 mRNA in TP53 wild-type, but not mutant, tumors.

CONCLUSIONS

These data suggest that the STAT3 locus is associated with both IBD and cancer. Further understanding the function of this variant in relation to TP53 could possibly explain the role of this gene in autoimmunity and cancer. Furthermore, an analysis of this locus, specifically in a population with IBD, could help to resolve the relationship between this SNP and cancer.

PreImplantation factor (PIF*) promotes embryotrophic and neuroprotective decidual genes: effect negated by epidermal growth factor

Background

Intimate embryo-maternal interaction is paramount for pregnancy success post-implantation. The embryo follows a specific developmental timeline starting with neural system, dependent on endogenous and decidual factors. Beyond altered genetics/epigenetics, post-natal diseases may initiate at prenatal/neonatal, post-natal period, or through a continuum. Preimplantation factor (PIF) secreted by viable embryos promotes implantation and trophoblast invasion. Synthetic PIF reverses neuroinflammation in non-pregnant models. PIF targets embryo proteins that protect against oxidative stress and protein misfolding. We report of PIF’s embryotrophic role and potential to prevent developmental disorders by regulating uterine milieu at implantation and first trimester.

Methods

PIF’s effect on human implantation (human endometrial stromal cells (HESC)) and first-trimester decidua cultures (FTDC) was examined, by global gene expression (Affymetrix), disease-biomarkers ranking (GeneGo), neuro-specific genes (Ingenuity) and proteins (mass-spectrometry). PIF co-cultured epidermal growth factor (EGF) in both HESC and FTDC (Affymetrix) was evaluated.

Results

In HESC, PIF promotes neural differentiation and transmission genes (TLX2, EPHA10) while inhibiting retinoic acid receptor gene, which arrests growth. PIF promotes axon guidance and downregulates EGF-dependent neuroregulin signaling. In FTDC, PIF promotes bone morphogenetic protein pathway (SMAD1, 53-fold) and axonal guidance genes (EPH5) while inhibiting PPP2R2C, negative cell-growth regulator, involved in Alzheimer’s and amyotrophic lateral sclerosis. In HESC, PIF affects angiotensin via beta-arrestin, transforming growth factor-beta (TGF-β), notch, BMP, and wingless-int (WNT) signaling pathways that promote neurogenesis involved in childhood neurodevelopmental diseases—autism and also affected epithelial-mesenchymal transition involved in neuromuscular disorders. In FTDC, PIF upregulates neural development and hormone signaling, while downregulating genes protecting against xenobiotic response leading to connective tissue disorders.

In both HESC and FTDC, PIF affects neural development and transmission pathways. In HESC interactome, PIF promotes FUS gene, which controls genome integrity, while in FTDC, PIF upregulates STAT3 critical transcription signal. EGF abolished PIF’s effect on HESC, decreasing metalloproteinase and prolactin receptor genes, thereby interfering with decidualization, while in FTDC, EGF co-cultured with PIF reduced ZHX2, gene that regulates neural AFP secretion.

Conclusions

PIF promotes decidual trophic genes and proteins to regulate neural development. By regulating the uterine milieu, PIF may decrease embryo vulnerability to post-natal neurodevelopmental disorders. Examination of PIF-based intervention strategies used during embryogenesis to improve pregnancy prognosis and reduce post-natal vulnerability is clearly in order.

Genetic update on inflammatory factors in ulcerative colitis: Review of the current literature

Ulcerative colitis (UC) is one of the main types of inflammatory bowel disease, which is caused by dysregulated immune responses in genetically predisposed individuals. Several genetic factors, including interleukin and interleukin receptor gene polymorphisms and other inflammation-related genes play central role in mediating and modulating the inflammation in the human body, thereby these can be the main cause of development of the disease. It is clear these data are very important for understanding the base of the disease, especially in terms of clinical utility and validity, but summarized literature is exiguous for challenge health specialist that can used in the clinical practice nowadays. This review summarizes the current literature on inflammation-related genetic polymorphisms which are associated with UC. We performed an electronic search of Pubmed Database among publications of the last 10 years, using the following medical subject heading terms: UC, ulcerative colitis, inflammation, genes, polymorphisms, and susceptibility.

Association between STAT3 gene polymorphisms and Crohn's disease susceptibility: a case-control study in a Chinese Han population

Background

Crohn’s disease (CD) is an immune-related disease with genetic predisposition. This study aimed to investigate the association of three polymorphisms in the signal transducer and activator of transcription 3 (STAT3) gene with CD risk in a Chinese population.

Methods

We conducted a hospital-based case–control study involving 232 CD patients and 272 controls. Genotyping was performed using polymerase chain reaction with sequence-specific primer method. Statistical analyses were conducted using logistic regression and genotype risk scoring.

Results

Significant differences were found between patients and controls in allele/genotype distributions of rs744166 (Pallele = 0.0008; Pgenotype = 0.003) and allele distributions of rs4796793 (P = 0.03). The risk for CD associated with the rs744166-A mutant allele decreased by 37% [95% confidence interval (CI): 0.48–0.83] under the additive model, 39% (95% CI: 0.43–0.81) under the dominant model and 57% (95% CI: 0.24–0.77) under the recessive model. Carriers of the rs4796793-G mutant allele exhibited 25% (95% CI: 0.58–0.98; P = 0.03) and 47% (95% CI: 0.30–0.95) decreased risks of developing CD under the additive and recessive models, respectively.

Conclusions

STAT3 rs744166 and rs4796793 polymorphisms may be associated with CD occurrence and used as a predictive factor of CD in Chinese Han populations.

Virtual Slides

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Inflammatory bowel disease: An increased risk factor for neurologic complications

Only a very few systematic studies have investigated the frequency of neurologic disorders in patients with Crohn’s disease (CD) and ulcerative colitis (UC), which are the two main types of inflammatory bowel disease (IBD). Results have been inconsistent and variable, owing to differences in case-finding methods and evaluated outcomes in different studies. The most frequent neurologic manifestations reported in CD and UC populations are cerebrovascular disease (with either arterial or venous events), demyelinating central nervous system disease, and peripheral neuropathy (whether axonal or demyelinating); however, the literature describes numerous nervous system disorders as being associated with IBD. The pathogenesis of nervous system tissue involvement in IBD has yet to be elucidated, although it seems to be related to immune mechanisms or prothrombotic states. The recently-introduced tumor necrosis factor (TNF) inhibitors have proven successful in controlling moderate to severe IBD activity. However, severe neurologic disorders associated with TNF inhibitors have been reported, which therefore raises concerns regarding the effect of anti-TNF-α antibodies on the nervous system. Although neurological involvement associated with IBD is rarely reported, gastroenterologists should be aware of the neurologic manifestations of IBD in order to provide early treatment, which is crucial for preventing major neurologic morbidity.

Inflammatory bowel disease and demyelination: more than just a coincidence?

Infliximab and other anti-TNF-α agents have been implicated for drug-induced demyelination in patients with inflammatory bowel diseases (IBDs). We evaluated existing data from MEDLINE and EMBASE and conducted a narrative review to investigate further the aforementioned association. Our literature search highlighted 34 case reports, 3 case-control studies, 1 prospective and 7 retrospective cohort studies published in English. Available data suggest that IBD patients can manifest demyelinating events in both central and peripheral nervous system, however, they are still insufficient to conclude whether anti-TNF-α therapies are an independent risk factor for demyelination. Prospective cohort studies with internal control groups are needed to estimate the true incidence of demyelinating disorders in patients with IBD and to elucidate if anti-TNF-α therapy increases further the risk of demyelination.

The regulation of reactive changes around multiple sclerosis lesions by phosphorylated signal transducer and activator of transcription

Activation of signal transducer and activator of transcription 3 (STAT3) by phosphorylation is thought to mediate anti-inflammatory responses to CNS injury. Several studies have reported an increase in phosphorylated STAT3 (pSTAT3) in peripheral T cells and monocytes from patients with multiple sclerosis (MS) during relapses, suggesting that pSTAT3 might represent an inflammatory marker. Here, we examined immunoreactivity for pSTAT3 in brain tissue samples from MS patients and controls. Phosphorylated STAT3 immunoreactivity was sparse within lesions, with no difference between active and inactive lesions. It was, however, significantly greater in white matter (WM) adjacent to active and inactive lesions; moreover, it was significantly greater in WM adjacent to active versus inactive lesions. Phosphorylated STAT3-positive cells were identified as astrocytes and macrophages/microglia. Phosphorylated STAT3 expression was also detected by Western blotting in WM of patients with MS. In comparison, pSTAT3 immunoreactivity was either rare or found focally in brain tissue samples from patients with other neurologic diseases. Our findings show that pSTAT3 does not correlate with inflammatory activity in MS lesions, but that it may play an important role in regulating reactive changes proximal to MS lesions.

PUMA: a unified framework for penalized multiple regression analysis of GWAS data

Penalized Multiple Regression (PMR) can be used to discover novel disease associations in GWAS datasets. In practice, proposed PMR methods have not been able to identify well-supported associations in GWAS that are undetectable by standard association tests and thus these methods are not widely applied. Here, we present a combined algorithmic and heuristic framework for PUMA (Penalized Unified Multiple-locus Association) analysis that solves the problems of previously proposed methods including computational speed, poor performance on genome-scale simulated data, and identification of too many associations for real data to be biologically plausible. The framework includes a new minorize-maximization (MM) algorithm for generalized linear models (GLM) combined with heuristic model selection and testing methods for identification of robust associations. The PUMA framework implements the penalized maximum likelihood penalties previously proposed for GWAS analysis (i.e. Lasso, Adaptive Lasso, NEG, MCP), as well as a penalty that has not been previously applied to GWAS (i.e. LOG). Using simulations that closely mirror real GWAS data, we show that our framework has high performance and reliably increases power to detect weak associations, while existing PMR methods can perform worse than single marker testing in overall performance. To demonstrate the empirical value of PUMA, we analyzed GWAS data for type 1 diabetes, Crohns's disease, and rheumatoid arthritis, three autoimmune diseases from the original Wellcome Trust Case Control Consortium. Our analysis replicates known associations for these diseases and we discover novel etiologically relevant susceptibility loci that are invisible to standard single marker tests, including six novel associations implicating genes involved in pancreatic function, insulin pathways and immune-cell function in type 1 diabetes; three novel associations implicating genes in pro- and anti-inflammatory pathways in Crohn's disease; and one novel association implicating a gene involved in apoptosis pathways in rheumatoid arthritis. We provide software for applying our PUMA analysis framework.

The influence of non-HLA gene polymorphisms and interactions on disease risk in a Western Australian multiple sclerosis cohort

Non-Human Leukocyte Antigen (HLA) genes have concomitant, although modest, effects on multiple sclerosis (MS) susceptibility; however findings have varied in different populations. Here we present the results of an association study of 16 single nucleotide polymorphisms (SNPs) in 10 non-HLA genes (IL7R, IL2RA, CLEC-16A, TYK2, CD58, IRF5, STAT3, CTLA-4, APOE, ICAM-1) in a Western Australian cohort of 350 MS patients and 498 population control subjects. Our results indicate that in this population, SNPs in IL7R, TYK2, IRF5 and APOE have modifying effects on MS susceptibility. We also found evidence of interactive protective effects between polymorphisms in the IL7R/CD58, CLEC-16A/CTLA-4, and TYK2/IRF5 genes, which in some instances are restricted within HLA- or gender-defined groups.

Combined serological, genetic, and inflammatory markers differentiate non-IBD, Crohn's disease, and ulcerative colitis patients

BACKGROUND

Previous studies have demonstrated that serological markers can assist in diagnosing inflammatory bowel disease (IBD). In this study, we aim to build a diagnostic tool incorporating serological markers, genetic variants, and markers of inflammation into a computational algorithm to examine patterns of combinations of markers to (1) identify patients with IBD and (2) differentiate patients with Crohn's disease (CD) from ulcerative colitis (UC).

METHODS

In this cross-sectional study, patient blood samples from 572 CD, 328 UC, 437 non-IBD controls, and 183 healthy controls from academic and community centers were analyzed for 17 markers: 8 serological markers (ASCA-IgA, ASCA-IgG, ANCA, pANCA, OmpC, CBir1, A4-Fla2, and FlaX), 4 genetic markers (ATG16L1, NKX2-3, ECM1, and STAT3), and 5 inflammatory markers (CRP, SAA, ICAM-1, VCAM-1, and VEGF). A diagnostic Random Forest algorithm was constructed to classify IBD, CD, and UC.

RESULTS

Receiver operating characteristic analysis compared the diagnostic accuracy of using a panel of serological markers only (ASCA-IgA, ASCA-IgG, ANCA, pANCA, OmpC, and CBir1) versus using a marker panel that in addition to the serological markers mentioned above also included gene variants, inflammatory markers, and 2 additional serological markers (A4-Fla2 and FlaX). The extended marker panel increased the IBD versus non-IBD discrimination area under the curve from 0.80 (95% confidence interval [CI], ±0.05) to 0.87 (95% CI, ±0.04; P < 0.001). The CD versus UC discrimination increased from 0.78 (95% CI, ±0.06) to 0.93 (95% CI, ±0.04; P < 0.001).

CONCLUSIONS

Incorporating a combination of serological, genetic, and inflammation markers into a diagnostic algorithm improved the accuracy of identifying IBD and differentiating CD from UC versus using serological markers alone.

Tissue inhibitor of metalloproteinase 1 is preferentially expressed in Th1 and Th17 T-helper cell subsets and is a direct STAT target gene

CD4(+) T helper (Th) cells differentiate into distinct effector subsets that are critical for host defense, but are also implicated in the pathogenesis of autoimmune disorders. Thelper17 (Th17) cells in particular are emerging as important drivers of multiple diseases including psoriasis, spondyloarthropathy and multiple sclerosis. To gain insight into the function of Th17 cells, we performed transcriptional profiling in hopes of elucidating products not previously recognized as being functionally relevant in these T cells. Herein, we demonstrate that tissue inhibitor of metalloproteinase 1 (TIMP1), a secreted protein with pleiotropic effects on cellular growth, survival and integrity of the extracellular matrix, is preferentially produced by Th17 and Th1 cells. We further show that Th1 and Th17 cell TIMP1 regulation follows separate mechanisms with a requirement for STAT4 in the former and STAT3 in the latter. Finally, we demonstrate that when restricted to T cells, expression of TIMP1 promotes neuropathology in experimental allergic encephalomyelitis.

Cytoplasmic STAT3 represses autophagy by inhibiting PKR activity

In a screen designed to identify novel inducers of autophagy, we discovered that STAT3 inhibitors potently stimulate the autophagic flux. Accordingly, genetic inhibition of STAT3 stimulated autophagy in vitro and in vivo, while overexpression of STAT3 variants, encompassing wild-type, nonphosphorylatable, and extranuclear STAT3, inhibited starvation-induced autophagy. The SH2 domain of STAT3 was found to interact with the catalytic domain of the eIF2α kinase 2 EIF2AK2, best known as protein kinase R (PKR). Pharmacological and genetic inhibition of STAT3 stimulated the activating phosphorylation of PKR and consequent eIF2α hyperphosphorylation. Moreover, PKR depletion inhibited autophagy as initiated by chemical STAT3 inhibitors or free fatty acids like palmitate. STAT3-targeting chemicals and palmitate caused the disruption of inhibitory STAT3-PKR interactions, followed by PKR-dependent eIF2α phosphorylation, which facilitates autophagy induction. These results unravel an unsuspected mechanism of autophagy control that involves STAT3 and PKR as interacting partners.

Interleukin-6 induces S100A9 expression in colonic epithelial cells through STAT3 activation in experimental ulcerative colitis

Background

Intestinal epithelium is essential for maintaining normal intestinal homeostasis; its breakdown leads to chronic inflammatory pathologies, such as inflammatory bowel diseases (IBDs). Although high concentrations of S100A9 protein and interleukin-6 (IL-6) are found in patients with IBD, the expression mechanism of S100A9 in colonic epithelial cells (CECs) remains elusive. We investigated the role of IL-6 in S100A9 expression in CECs using a colitis model.

Methods

IL-6 and S100A9 expression, signal transducer and activator of transcription 3 (STAT3) phosphorylation, and infiltration of immune cells were analyzed in mice with dextran sulfate sodium (DSS)-induced colitis. The effects of soluble gp130-Fc protein (sgp130Fc) and S100A9 small interfering (si) RNA (si-S100A9) on DSS-induced colitis were evaluated. The molecular mechanism of S100A9 expression was investigated in an IL-6-treated Caco-2 cell line using chromatin immunoprecipitation assays.

Results

IL-6 concentrations increased significantly in the colon tissues of DSS-treated mice. sgp130Fc or si-S100A9 administration to DSS-treated mice reduced granulocyte infiltration in CECs and induced the down-regulation of S100A9 and colitis disease activity. Treatment with STAT3 inhibitors upon IL-6 stimulation in the Caco-2 cell line demonstrated that IL-6 mediated S100A9 expression through STAT3 activation. Moreover, we found that phospho-STAT3 binds directly to the S100A9 promoter. S100A9 may recruit immune cells into inflamed colon tissues.

Conclusions

Elevated S100A9 expression in CECs mediated by an IL-6/STAT3 signaling cascade may play an important role in the development of colitis.

Meta-analysis of published studies identified eight additional common susceptibility loci for Crohn's disease and ulcerative colitis

BACKGROUND

Both ulcerative colitis (UC) and Crohn's disease (CD) have a complex etiology involving multiple genetic and environmental factors. Many genome-wide association studies (GWAS) and subsequent replication studies revealed that both diseases share some of the susceptibility loci; however, common genetic factors for both diseases are not fully elucidated. This study is aimed to identify the common genetic factors for CD and UC by a meta-analysis of published studies.

METHODS

We first reviewed the 10 GWAS for CD to select candidate single nucleotide polymorphisms (SNPs). Next, we performed a PubMed literature search up to June 30, 2010 and carried out a systemic review of published studies that examined the association of CD susceptibility loci in UC patients. Meta-analysis was carried out using the inverse variance-weighted method or the DerSimonian-Laird method after estimating the heterogeneity among the studies. The data for highly linked SNPs were combined. Finally, we performed a meta-analysis of 43 published studies in 45 SNPs located at 33 loci by using a total of 4852 to 31,125 subjects.

RESULTS

We confirmed the association of 17 reported common susceptibility loci. Moreover, we found associations at eight additional loci: GCKR, ATG16L1, CDKAL1, ZNF365, LRRK2-MUC19, C13orf31, PTPN2, and SBNO2. The genetic risk of each locus was modest (odds ratios ranged from 1.05-1.22) except IL23R.

CONCLUSIONS

These results indicate that CD and UC share many susceptibility loci with small genetic effect. Our data provide further understanding of the common pathogenesis between CD and UC.

Opposing regulation of the locus encoding IL-17 through direct, reciprocal actions of STAT3 and STAT5

Interleukin 2 (IL-2), a cytokine linked to human autoimmune disease, limits IL-17 production. Here we found that deletion of the gene encoding the transcription factor STAT3 in T cells abrogated IL-17 production and attenuated autoimmunity associated with IL-2 deficiency. Whereas STAT3 induced IL-17 and the transcription factor RORγt and inhibited the transcription factor Foxp3, IL-2 inhibited IL-17 independently of Foxp3 and RORγt. STAT3 and STAT5 bound to multiple common sites across the locus encoding IL-17. The induction of STAT5 binding by IL-2 was associated with less binding of STAT3 at these sites and the inhibition of associated active epigenetic marks. 'Titration' of the relative activation of STAT3 and STAT5 modulated the specification of cells to the IL-17-producing helper T cell (T(H)17 cell) subset. Thus, the balance rather than the absolute magnitude of these signals determined the propensity of cells to make a key inflammatory cytokine.

IL12A, MPHOSPH9/CDK2AP1 and RGS1 are novel multiple sclerosis susceptibility loci

A recent meta-analysis identified seven single-nucleotide polymorphisms (SNPs) with suggestive evidence of association with multiple sclerosis (MS). We report an analysis of these polymorphisms in a replication study that includes 8,085 cases and 7,777 controls. A meta-analysis across the replication collections and a joint analysis with the discovery data set were performed. The possible functional consequences of the validated susceptibility loci were explored using RNA expression data. For all of the tested SNPs, the effect observed in the replication phase involved the same allele and the same direction of effect observed in the discovery phase. Three loci exceeded genome-wide significance in the joint analysis: RGS1 (P value=3.55 x 10(-9)), IL12A (P=3.08 x 10(-8)) and MPHOSPH9/CDK2AP1 (P=3.96 x 10(-8)). The RGS1 risk allele is shared with celiac disease (CD), and the IL12A risk allele seems to be protective for celiac disease. Within the MPHOSPH9/CDK2AP1 locus, the risk allele correlates with diminished RNA expression of the cell cycle regulator CDK2AP1; this effect is seen in both lymphoblastic cell lines (P=1.18 x 10(-5)) and in peripheral blood mononuclear cells from subjects with MS (P=0.01). Thus, we report three new MS susceptibility loci, including a novel inflammatory disease locus that could affect autoreactive cell proliferation.