The nuclear IκB family protein IκBNS influences the susceptibility to experimental autoimmune encephalomyelitis in a murine model

Transcriptional upregulation of galectin-3 in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune, demyelinating disorder of the central nervous system (CNS) affecting approximately 2.5 million people worldwide. The mechanisms underlying the pathogenesis of MS are still only partially elucidated. Galectins are a family of β-galactoside-binding lectins that are involved in the regulation of immune and inflammatory responses and have been shown to exert a role in the maintenance of central nervous system (CNS) homeostasis. There has been an increasing interest in the role of galectin-3 in neuroinflammation and neurodegeneration. In the current study, we have evaluated the expression levels of galectin-3 in different cellular populations involved in the etiopathogenesis of MS. We have observed dramatically higher transcriptomic levels of galectin-3 in encephalitogenic CD4+ T cells in a preclinical model of MS, the MOG-induced experimental allergic encephalomyelitis (EAE). Also, significantly higher levels of galectin-3 were found in microglial cells, astrocytes, and oligodendrocytes isolated from the spinal cord of EAE mice, as well as in human MS-related white matter lesions. Modular co-expression analysis revealed that galectin-3 is co-expressed with genes involved in the regulation of microglia, cytokine production, and chemotaxis. This is the first comprehensive analysis of the expression of galectin-3 in MS, further strengthening its potential pathogenetic role in the etiopathogenesis of this CNS autoimmune disorder.

The central inflammatory regulator IκBζ: induction, regulation and physiological functions

IκBζ (encoded by NFKBIZ) is the most recently identified IkappaB family protein. As an atypical member of the IkappaB protein family, NFKBIZ has been the focus of recent studies because of its role in inflammation. Specifically, it is a key gene in the regulation of a variety of inflammatory factors in the NF-KB pathway, thereby affecting the progression of related diseases. In recent years, investigations into NFKBIZ have led to greater understanding of this gene. In this review, we summarize the induction of NFKBIZ and then elucidate its transcription, translation, molecular mechanism and physiological function. Finally, the roles played by NFKBIZ in psoriasis, cancer, kidney injury, autoimmune diseases and other diseases are described. NFKBIZ functions are universal and bidirectional, and therefore, this gene may exert a great influence on the regulation of inflammation and inflammation-related diseases.

IκBNS-deficiency protects mice from fatal Listeria monocytogenes infection by blunting pro-inflammatory signature in Ly6Chigh monocytes and preventing exaggerated innate immune responses

IκB proteins regulate the inhibition and activation of NF-κB transcription factor complexes. While classical IκB proteins keep NF-κB complexes inactive in the cytoplasm, atypical IκB proteins act on activated NF-κB complexes located in the nucleus. Most of the knowledge regarding the function of IκB proteins has been collected in vitro, while far less is known regarding their impact on activation and regulation of immune responses during in vivo infections. Combining in vivo Listeria monocytogenes (Lm) infection with comparative ex vivo transcriptional profiling of the hepatic response to the pathogen we observed that in contrast to wild type mice that mounted a robust inflammatory response, IκB_NS-deficiency was generally associated with a transcriptional repression of innate immune responses. Whole tissue transcriptomics revealed a pronounced IκB_NS-dependent reduction of myeloid cell-associated transcripts in the liver together with an exceptionally high Nfkbid promoter activity uncovered in Ly6C^high inflammatory monocytes prompted us to further characterize the specific contribution of IκB_NS in the inflammatory response of monocytes to the infectious agent. Indeed, Ly6C^high monocytes primed during Lm infection in the absence of IκB_NS displayed a blunted response compared to wild type-derived Ly6C^high monocytes as evidenced by the reduced early expression of hallmark transcripts of monocyte-driven inflammation such as Il6, Nos2 and Il1β. Strikingly, altered monocyte activation in IκB_NS-deficient mice was associated with an exceptional resistance against Lm infection and protection was associated with a strong reduction in immunopathology in Lm target organs. Of note, mice lacking IκB_NS exclusively in myeloid cells failed to resist Lm infection, indicating that the observed effect was not monocyte intrinsic but monocyte extrinsic. While serum cytokine-profiling did not discover obvious differences between wild type and IκB_NS ^-/- mice for most of the analyzed mediators, IL-10 was virtually undetectable in IκB_NS-deficient mice, both in the steady state and following Lm infection. Together, we show here a crucial role for IκB_NS during Lm infection with IκB_NS-deficient mice showing an overall blunted pro-inflammatory immune response attributed to a reduced pro-inflammatory signature in Ly6C^high monocytes. Reduced immunopathology and complete protection of mice against an otherwise fatal Lm infection identified IκB_NS as molecular driver of inflammation in listeriosis.

Emerging role of IκBζ in inflammation: Emphasis on psoriasis

Psoriasis is a chronic inflammatory disorder affecting skin and joints that results from immunological dysfunction such as enhanced IL-23 induced Th-17 differentiation. IkappaB-Zeta (IκBζ) is an atypical transcriptional factor of the IκB protein family since, contrary to the other family members, it positively regulates NF-κB pathway by being exclusively localized into the nucleus. IκBζ deficiency reduces visible manifestations of experimental psoriasis by diminishing expression of psoriasis-associated genes. It is thus tempting to consider IκBζ as a potential therapeutic target for psoriasis as well as for other IL23/IL17-mediated inflammatory diseases. In this review, we will discuss the regulation of expression of NFKBIZ and its protein IκBζ, its downstream targets, its involvement in pathogenesis of multiple disorders with emphasis on psoriasis and evidences supporting that inhibition of IκBζ may be a promising alternative to current therapeutic managements of psoriasis.

ADAM12 is a costimulatory molecule that determines Th1 cell fate and mediates tissue inflammation

A disintegrin and metalloproteinase (ADAM)12 was previously found to be expressed in T cells in the inflamed brain. However, the function of ADAM12 in T-cell responses in general and in tissue inflammation has not been examined. Here, we studied the role of ADAM12 in T-cell responses, fate determination on activation, and its functions in T cells to mediate tissue inflammation. We identified ADAM12 as a costimulatory molecule that is expressed on naive T cells and downregulated on stimulation. ADAM12 mimics CD28 costimulatory signaling to activate and induce the proliferation of T-helper 1 (Th1) cells. Monoclonal ADAM12 Fab antibodies trigger T-cell activation by amplifying TCR signaling to stimulate T-bet-mediated IFNγ production. Lack of genomic ADAM12 and its knockdown in T cells diminished T-bet and IFNγ production in Th1 cells, whereas other T cells, including Th17 cells, were unaffected. ADAM12 had similar functions in vivo on myelin antigen (MOG35-55)-induced T-cell activation. We found that genetic loss of ADAM12 profoundly alleviated Th1-mediated neuroinflammation and thus disease severity in experimental autoimmune encephalomyelitis, a model of multiple sclerosis. Transcriptomic profiling of MOG35-55-specific ADAM12-/- T cells revealed differentially expressed genes that are important for T-cell activation, proliferation, and costimulatory signaling and Th1 pathogenicity, consistent with their inability to cause T-cell-mediated skin inflammation in a model of adoptive delayed-type hypersensitivity. We conclude that ADAM12 is a T-cell costimulatory molecule that contributes to the pathogenesis of tissue inflammation and a potential target for the treatment of Th1-mediated diseases.

The Curcumin Analog GO-Y030 Controls the Generation and Stability of Regulatory T Cells

Regulatory T cells (Tregs) play a crucial role in preventing antitumor immune responses in cancer tissues. Cancer tissues produce large amounts of transforming growth factor beta (TGF-β), which promotes the generation of Foxp3+ Tregs from naïve CD4+ T cells in the local tumor microenvironment. TGF-β activates nuclear factor kappa B (NF-κB)/p300 and SMAD signaling, which increases the number of acetylated histones at the Foxp3 locus and induces Foxp3 gene expression. TGF-β also helps stabilize Foxp3 expression. The curcumin analog and antitumor agent, GO-Y030, prevented the TGF-β-induced generation of Tregs by preventing p300 from accelerating NF-κB-induced Foxp3 expression. Moreover, the addition of GO-Y030 resulted in a significant reduction in the number of acetylated histones at the Foxp3 promoter and at the conserved noncoding sequence 1 regions that are generated in response to TGF-β. In vivo tumor models demonstrated that GO-Y030-treatment prevented tumor growth and reduced the Foxp3+ Tregs population in tumor-infiltrating lymphocytes. Therefore, GO-Y030 exerts a potent anticancer effect by controlling Treg generation and stability.

NF-κB and Its Regulators During Pregnancy

The transcriptional factor NF-κB is a nuclear factor involved in both physiological and pathological processes. This factor can control the transcription of more than 400 genes, including cytokines, chemokines, and their modulators, immune and non-immune receptors, proteins involved in antigen presentation and cell adhesion, acute phase and stress response proteins, regulators of apoptosis, growth factors, other transcription factors and their regulators, as well as different enzymes; all these molecules control several biological processes. NF-κB is a tightly regulated molecule that has also been related to apoptosis, cell proliferation, inflammation, and the control of innate and adaptive immune responses during onset of labor, in which it has a crucial role; thus, early activation of this factor may have an adverse effect, by inducing premature termination of pregnancy, with bad outcomes for the mother and the fetus, including product loss. Reviews compiling the different activities of NF-κB have been reported. However, an update regarding NF-κB regulation during pregnancy is lacking. In this work, we aimed to describe the state of the art around NF-κB activity, its regulatory role in pregnancy, and the effect of its dysregulation due to invasion by pathogens like Trichomonas vaginalis and Toxoplasma gondii as examples.

Galectin-3 as a Next-Generation Biomarker for Detecting Early Stage of Various Diseases

Galectin-3 is a β-galactoside-binding lectin which is important in numerous biological activities in various organs, including cell proliferation, apoptotic regulation, inflammation, fibrosis, and host defense. Galectin-3 is predominantly located in the cytoplasm and expressed on the cell surface, and then often secreted into biological fluids, like serum and urine. It is also released from injured cells and inflammatory cells under various pathological conditions. Many studies have revealed that galectin-3 plays an important role as a diagnostic or prognostic biomarker for certain types of heart disease, kidney disease, viral infection, autoimmune disease, neurodegenerative disorders, and tumor formation. In particular, it has been recognized that galectin-3 is extremely useful for detecting many of these diseases in their early stages. The purpose of this article is to review and summarize the recent literature focusing on the biomarker characteristics and long-term outcome predictions of galectin-3, in not only patients with various types of diseases, but associated animal models.

Essential role of IκBNS for in vivo CD4+ T-cell activation, proliferation, and Th1-cell differentiation during Listeria monocytogenes infection in mice

Acquisition of effector functions in T cells is guided by transcription factors, including NF‐κB, that itself is tightly controlled by inhibitory proteins. The atypical NF‐κB inhibitor, IκB_NS, is involved in the development of Th1, Th17, and regulatory T (Treg) cells. However, it remained unclear to which extend IκB_NS contributed to the acquisition of effector function in T cells specifically responding to a pathogen during in vivo infection. Tracking of adoptively transferred T cells in Listeria monocytogenes infected mice antigen‐specific activation of CD4⁺ T cells following in vivo pathogen encounter to strongly rely on IκB_NS. While IκB_NS was largely dispensable for the acquisition of cytotoxic effector function in CD8⁺ T cells, IκB_NS‐deficient Th1 effector cells exhibited significantly reduced proliferation, marked changes in the pattern of activation marker expression, and reduced production of the Th1‐cell cytokines IFN‐γ, IL‐2, and TNF‐α. Complementary in vitro analyses using cells from novel reporter and inducible knockout mice revealed that IκB_NS predominantly affects the early phase of Th1‐cell differentiation while its function in terminally differentiated cells appears to be negligible. Our data suggest IκB_NS as a potential target to modulate specifically CD4⁺ T‐cell responses.

Roquin targets mRNAs in a 3'-UTR-specific manner by different modes of regulation

The RNA-binding proteins Roquin-1 and Roquin-2 redundantly control gene expression and cell-fate decisions. Here, we show that Roquin not only interacts with stem–loop structures, but also with a linear sequence element present in about half of its targets. Comprehensive analysis of a minimal response element of the Nfkbid 3′-UTR shows that six stem–loop structures cooperate to exert robust and profound post-transcriptional regulation. Only binding of multiple Roquin proteins to several stem–loops exerts full repression, which redundantly involved deadenylation and decapping, but also translational inhibition. Globally, most Roquin targets are regulated by mRNA decay, whereas a small subset, including the Nfat5 mRNA, with more binding sites in their 3′-UTRs, are also subject to translational inhibition. These findings provide insights into how the robustness and magnitude of Roquin-mediated regulation is encoded in complex cis-elements.

Roquin targets are known to contain two types of sequence-structure motifs, the constitutive and the alternative decay elements (CDE and ADE). Here, the authors describe a linear Roquin binding element (LBE) also involved in target recognition, and show that Roquin binding affects the translation of a subset of targeted mRNAs.

Posttranscriptional Gene Regulation of T Follicular Helper Cells by RNA-Binding Proteins and microRNAs

T follicular helper (Tfh) cells are critically involved in the establishment of potent antibody responses against infectious pathogens, such as viruses and bacteria, but their dysregulation may also result in aberrant antibody responses that frequently coincide with autoimmune diseases or allergies. The fate and identity of Tfh cells is tightly controlled by gene regulation on the transcriptional and posttranscriptional level. Here, we provide deeper insights into the posttranscriptional mechanisms that regulate Tfh cell differentiation, function, and plasticity through the actions of RNA-binding proteins (RBPs) and small endogenously expressed regulatory RNAs called microRNAs (miRNAs). The Roquin family of RBPs has been shown to dampen spontaneous activation and differentiation of naïve CD4⁺ T cells into Tfh cells, since CD4⁺ T cells with Roquin mutations accumulate as Tfh cells and provide inappropriate B cell help in the production of autoantibodies. Moreover, Regnase-1, an endoribonuclease that regulates a set of targets, which strongly overlaps with that of Roquin, is crucial for the prevention of autoantibody production. Interestingly, both Roquin and Regnase-1 proteins are cleaved and inactivated after TCR stimulation by the paracaspase MALT1. miRNAs are expressed in naïve CD4⁺ T cells and help preventing spontaneous differentiation into effector cells. While most miRNAs are downregulated upon T cell activation, several miRNAs have been shown to regulate the fate of these cells by either promoting (e.g., miR-17-92 and miR-155) or inhibiting (e.g., miR-146a) Tfh cell differentiation. Together, these different aspects highlight a complex and dynamic regulatory network of posttranscriptional gene regulation in Tfh cells that may also be active in other T helper cell populations, including Th1, Th2, Th17, and Treg.

Specific covalent inhibition of MALT1 paracaspase suppresses B cell lymphoma growth

The paracaspase MALT1 plays an essential role in activated B cell-like diffuse large B cell lymphoma (ABC DLBCL) downstream of B cell and TLR pathway genes mutated in these tumors. Although MALT1 is considered a compelling therapeutic target, the development of tractable and specific MALT1 protease inhibitors has thus far been elusive. Here, we developed a target engagement assay that provides a quantitative readout for specific MALT1-inhibitory effects in living cells. This enabled a structure-guided medicinal chemistry effort culminating in the discovery of pharmacologically tractable, irreversible substrate-mimetic compounds that bind the MALT1 active site. We confirmed that MALT1 targeting with compound 3 is effective at suppressing ABC DLBCL cells in vitro and in vivo. We show that a reduction in serum IL-10 levels exquisitely correlates with the drug pharmacokinetics and degree of MALT1 inhibition in vitro and in vivo and could constitute a useful pharmacodynamic biomarker to evaluate these compounds in clinical trials. Compound 3 revealed insights into the biology of MALT1 in ABC DLBCL, such as the role of MALT1 in driving JAK/STAT signaling and suppressing the type I IFN response and MHC class II expression, suggesting that MALT1 inhibition could prime lymphomas for immune recognition by cytotoxic immune cells.

Posttranscriptional regulation of T helper cell fate decisions

Hoefig and Heissmeyer review how microRNAs, long noncoding RNAs, RNA-binding proteins, and ubiquitin-modifying enzymes regulate T helper cell differentiation downstream of transcription.

T helper cell subsets orchestrate context- and pathogen-specific responses of the immune system. They mostly do so by secreting specific cytokines that attract or induce activation and differentiation of other immune or nonimmune cells. The differentiation of T helper 1 (Th1), Th2, T follicular helper, Th17, and induced regulatory T cell subsets from naive T cells depends on the activation of intracellular signal transduction cascades. These cascades originate from T cell receptor and costimulatory receptor engagement and also receive critical input from cytokine receptors that sample the cytokine milieu within secondary lymphoid organs. Signal transduction then leads to the expression of subset-specifying transcription factors that, in concert with other transcription factors, up-regulate downstream signature genes. Although regulation of transcription is important, recent research has shown that posttranscriptional and posttranslational regulation can critically shape or even determine the outcome of Th cell differentiation. In this review, we describe how specific microRNAs, long noncoding RNAs, RNA-binding proteins, and ubiquitin-modifying enzymes regulate their targets to skew cell fate decisions.

Nuclear Factor-kappaB in Autoimmunity: Man and Mouse

NF-κB (nuclear factor-kappa B) is a transcription complex crucial for host defense mediated by innate and adaptive immunity, where canonical NF-κB signaling, mediated by nuclear translocation of RelA, c-Rel, and p50, is important for immune cell activation, differentiation, and survival. Non-canonical signaling mediated by nuclear translocation of p52 and RelB contributes to lymphocyte maturation and survival and is also crucial for lymphoid organogenesis. We outline NF-κB signaling and regulation, then summarize important molecular contributions of NF-κB to mechanisms of self-tolerance. We relate these mechanisms to autoimmune phenotypes described in what is now a substantial catalog of immune defects conferred by mutations in NF-κB pathways in mouse models. Finally, we describe Mendelian autoimmune syndromes arising from human NF-κB mutations, and speculate on implications for understanding sporadic autoimmune disease.

IκBNS induces Muc5ac expression in epithelial cells and causes airway hyper-responsiveness in murine asthma models

BACKGROUND

In allergic asthma, environmental allergens including house dust mite (HDM) trigger pattern recognition receptors and activate downstream signaling pathways including NF-κB pathways not only in immune cells but also in airway epithelial cells. Recent studies have shown that NF-κB activation is regulated positively or negatively depending on the cellular context by IκBNS (encoded by the gene Nfkbid), one of atypical IκB proteins, in the nucleus. Therefore, we hypothesized that IκBNS expressed in immune cells or epithelial cells is involved in the regulation of asthmatic responses.

AIM

To determine the roles of IκBNS in HDM-induced asthmatic responses.

METHODS

Roles of IκBNS in HDM-induced airway inflammation and airway hyper-responsiveness (AHR) were examined by using IκBNS-deficient (Nfkbid^-/- ) mice. Roles of IκBNS expressed in hematopoietic cells and nonhematopoietic cells were separately evaluated by bone marrow chimeric mice. Roles of IκBNS expressed in murine tracheal epithelial cells (mTECs) were examined by air-liquid interface culture.

RESULTS

House dust mite-induced airway inflammation and AHR were exacerbated in mice lacking IκBNS in hematopoietic cells. In contrast, HDM-induced airway inflammation was exacerbated, but AHR was attenuated in mice lacking IκBNS in nonhematopoietic cells. The induction of Muc5ac, a representative mucin in asthmatic airways, was reduced in Nfkbid^-/- mTEC, whereas the induction of Spdef, a master regulator of goblet cell metaplasia, was not impaired in Nfkbid^-/- mTEC. Moreover, IκBNS bound to and activated the MUC5AC distal promoter in epithelial cells.

CONCLUSION

IκBNS is involved in inducing Muc5ac expression in lung epithelial cells and causing AHR in HDM-induced asthma models.

c-REL and IκBNS Govern Common and Independent Steps of Regulatory T Cell Development from Novel CD122-Expressing Pre-Precursors

Foxp3-expressing regulatory T cells (Tregs) are essential regulators of immune homeostasis and, thus, are prime targets for therapeutic interventions of diseases such as cancer and autoimmunity. c-REL and IκB_NS are important regulators of Foxp3 induction in Treg precursors upon γ-chain cytokine stimulation. In c-REL/IκB_NS double-deficient mice, Treg numbers were dramatically reduced, indicating that together, c-REL and IκB_NS are pivotal for Treg development. However, despite the highly reduced Treg compartment, double-deficient mice did not develop autoimmunity even when aged to more than 1 y, suggesting that c-REL and IκB_NS are required for T cell effector function as well. Analyzing Treg development in more detail, we identified a CD122⁺ subset within the CD25^-Foxp3^- precursor population, which gave rise to classical CD25⁺Foxp3^- Treg precursors. Importantly, c-REL, but not IκB_NS, controlled the generation of classical CD25⁺Foxp3^- precursors via direct binding to the Cd25 locus. Thus, we propose that CD4⁺GITR⁺CD122⁺CD25^-Foxp3^- cells represent a Treg pre-precursor population, whose transition into Treg precursors is mediated via c-REL.

NF-κB Pathways in the Pathogenesis of Multiple Sclerosis and the Therapeutic Implications

Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathways are involved in cell immune responses, apoptosis and infections. In multiple sclerosis (MS), NF-κB pathways are changed, leading to increased levels of NF-κB activation in cells. This may indicate a key role for NF-κB in MS pathogenesis. NF-κB signaling is complex, with many elements involved in its activation and regulation. Interestingly, current MS treatments are found to be directly or indirectly linked to NF-κB pathways and act to adjust the innate and adaptive immune system in patients. In this review, we will first focus on the intricacies of NF-κB signaling, including the activating pathways and regulatory elements. Next, we will theorize about the role of NF-κB in MS pathogenesis, based on current research findings, and discuss some of the associated therapeutic implications. Lastly, we will review four new MS treatments which interrupt NF-κB pathways—fingolimod, teriflunomide, dimethyl fumarate (DMF) and laquinimod (LAQ)—and explain their mechanisms, and the possible strategy for MS treatments in the future.

Alternative splicing of MALT1 controls signalling and activation of CD4(+) T cells

MALT1 channels proximal T-cell receptor (TCR) signalling to downstream signalling pathways. With MALT1A and MALT1B two conserved splice variants exist and we demonstrate here that MALT1 alternative splicing supports optimal T-cell activation. Inclusion of exon7 in MALT1A facilitates the recruitment of TRAF6, which augments MALT1 scaffolding function, but not protease activity. Naive CD4⁺ T cells express almost exclusively MALT1B and MALT1A expression is induced by TCR stimulation. We identify hnRNP U as a suppressor of exon7 inclusion. Whereas selective depletion of MALT1A impairs T-cell signalling and activation, downregulation of hnRNP U enhances MALT1A expression and T-cell activation. Thus, TCR-induced alternative splicing augments MALT1 scaffolding to enhance downstream signalling and to promote optimal T-cell activation.

MALT1 regulates NFκB signalling both as a scaffolding protein and as a protease. Here the authors show that during T cell activation the expression of MALT1 gene switches to an alternatively spliced variant, which increases TCR signal transduction due to enhanced TRAF6 binding.

The atypical IκB protein IκB(NS) is important for Toll-like receptor-induced interleukin-10 production in B cells

Although a major function of B cells is to mediate humoral immunity by producing antigen-specific antibodies, a specific subset of B cells is important for immune suppression, which is mainly mediated by the secretion of the anti-inflammatory cytokine interleukin-10 (IL-10). However, the mechanism by which IL-10 is induced in B cells has not been fully elucidated. Here, we report that IκBNS , an inducible nuclear IκB protein, is important for Toll-like receptor (TLR)-mediated IL-10 production in B cells. Studies using IκB(NS) knockout mice revealed that the number of IL-10-producing B cells is reduced in IκB(NS)(-/-) spleens and that the TLR-mediated induction of cytoplasmic IL-10-positive cells and IL-10 secretion in B cells are impaired in the absence of IκB(NS). The impairment of IL-10 production by a lack of IκB(NS) was not observed in TLR-triggered macrophages or T-cell-receptor-stimulated CD4(+) CD25(+) T cells. In addition, IκB(NS)-deficient B cells showed reduced expression of Prdm1 and Irf4 and failed to generate IL-10(+) CD138(+) plasmablasts. These results suggest that IκB(NS) is selectively required for IL-10 production in B cells responding to TLR signals, so defining an additional role for IκB(NS) in the control of the B-cell-mediated immune responses.

Altered Th17/Treg balance and dysregulated IL-1β response influence susceptibility/resistance to experimental autoimmune arthritis

This study was aimed at gaining an insight into immune mechanisms of differential susceptibility to autoimmunity of individuals sharing the same major histocompatibility complex by studying arthritis-susceptible Lewis (LEW) and arthritis-resistant Wistar Kyoto (WKY) rats (both RT.1(l)) using the adjuvant arthritis (AA) model of rheumatoid arthritis (RA). Lymph node cells (LNC) and synovium-infiltrating cells (SIC) of LEW and WKY rat subjected to an arthritogenic challenge were tested. The frequency of T helper 17 (Th17) and T regulatory (Treg) cells was determined by flow cytometry, whereas serum and spleen adherent cell (SAC)-derived supernatant were analyzed for specific cytokines and chemokines. We observed that WKY rats are not deficient in generating a Th17 response to the arthritogenic challenge in LNC (periphery); however, the Th17/Treg ratio is markedly reduced in the joint (target organ) of WKY versus LEW rats because of reduced Th17 levels therein in WKY rats. These results suggest differential and selective decrease in Th17 cell migration into the joints of WKY rats. Interestingly, serum levels of chemokines RANTES and MCP-1 were reduced in WKY rats. Furthermore, WKY rats showed reduced serum IL-1β level in vivo but no defect in IL-1β production by SAC in vitro, suggesting an effective in vivo regulation of IL-1β response. We also unraveled the role of interferon-γ (IFNγ), which we have previously reported to be increased in WKY versus LEW rats, in regulation of IL-1β. Thus, reduced Th17/Treg ratio in the target organ (joints) and decreased systemic IL-1β might contribute to the AA-resistance of WKY rats; whereas the converse factors render LEW more vulnerable to AA.

Correction: The Nuclear IκB Family Protein IκBNS Influences the Susceptibility to Experimental Autoimmune Encephalomyelitis in a Murine Model

[This corrects the article DOI: 10.1371/journal.pone.0110838.].