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The mechanisms by which lamin A/C in CD4+ T-cells control intestinal homeostasis and can cause inflammatory bowel disease (IBD) are unknown. Here, we explore lamin A/C in a mouse model of IBD. Adoptive transfer to Rag1-/- mice of Lmna-/- CD4+ T-cells, which have enhanced regulatory T-cells (Treg) differentiation and function, induced less severe IBD than wild-type T-cells. Lamin A/C deficiency in CD4+ T-cells enhanced transcription of the Treg master regulator FOXP3, thus promoting Treg differentiation, and reduced Th1 polarization, due to epigenetic changes in the Th1 master regulator T-bet. In mesenteric lymph nodes, retinoic acid (RA) released by CD103+ dendritic cells downregulated lamin A/C in CD4+ T-cells, enhancing Treg differentiation. However, non-RA-producing CD103- dendritic cells predominated in peripheral lymph nodes, facilitating lamin A/C expression in CD4+ T-cells and therefore Th1 differentiation. Our findings establish lamin A/C as a key regulator of Th differentiation in physiological conditions and show it as a potential immune-regulatory target in IBD. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. This study was supported by grants to PC from the Research Council of Norway, to JMG-G from ISCIII (PI14/00526; PI17/01395; CP11/00145; CPII16/00022; EuroCellNet COST Action CA15214), the Miguel Servet Program and Fundación Ramón Aréces; to VA (RD12/0042/0028 SAF2013-46663-R, SAF2016-79490-R); to FS-M (SAF2017-82886-R; ERC-2011-AdG 294340-GENTRIS, CIBER CARDIOVASCULAR, PIE 13.0004-BIOIMID and CAM-B2017/BMD-3671-INFLAMUNE), to GC and JLP (PI16/00032 and RETICs RD16/0012 RIER), and to JV (BIO2015-67580-P; PRB3, IPT17/0019 - ISCIII-SGEFI/ERDF, ProteoRed) with co-funding from the European Regional Development Fund (ERDF) “Una manera de hacer Europa”. The CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the Ministerio de Ciencia, Innovación y Universidades (MCNU) and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (SEV-2015-0505). RTF is supported by the Fundación Ramón Aréces, VZG by ISCIII, BHF by the Instituto de Investigación Hospital 12 de Octubre (i+12), and JMG-G by the ISCIII Miguel Servet Program, i+12 and Universidad Autónoma de Madrid (UAM). Sí

The mechanisms by which lamin A/C in CD4

Vitamin D analogues can reduce TGF-b pro- fibrotic signaling in dermal fibroblasts, but they may also induce a potentially pro-fibrotic thymic stromal lympho- poietin (TSLP)-dependent Th2 cytokine local response. We have analyzed the net effect of topical vitamin D analogue calcipotriol (CPT) on the cytokine profile and the develop- ment of fibrosis in experimental model of bleomycin-induced fibrosis. Mice were simultaneously treated with topical CPT or vehicle cream and skin fibrosis was measured by collagen deposition, Masson's trichrome staining and hydroxyproline content. Cytokine and TSLP gene expression was evaluated by quantitative RT-PCR. We showed that in bleomycin injected skin, CPT administration significantly enhanced TSLP and IL-13 gene expression, but did not modify the expression of other cytokines. Skin fibrosis and hydroxy- proline content were significantly reduced in CPT compared to vehicle-treated mice. In normal skin, topical administration of CPT lacked a direct pro-fibrotic effect. Our results dem- onstrate that topical CPT superinduces the expression of the TSLP/IL-13 Th2 axis in fibrotic skin, but it has a net anti- fibrotic effect. These data support the therapeutic use of topical vitamin D analogues for skin fibrosis.

Objective The role of most p38 MAPK isoforms in inflammatory arthritis is not known. This study was undertaken to evaluate p38γ and p38δ deficiency in the collagen-induced arthritis (CIA) model. Methods Wild-type, p38γ−/−, p38δ−/−, and p38γ/δ−/− mice were immunized with chicken type II collagen, and disease activity was evaluated by semiquantitative scoring and histologic assessment. Serum cytokine levels and in vitro T cell cytokine responses were quantified by flow cytometry and multiplex analysis, and serum anticollagen antibody levels by enzyme-linked immunosorbent assay. Cytokine and p38 MAPK isoform expression in joints were determined by quantitative polymerase chain reaction. Results Compound p38γ and p38δ deficiency markedly reduced arthritis severity compared with that in wild-type mice, whereas lack of either p38γ or p38δ had an intermediate effect. Joint damage was minimal in arthritic p38γ/δ−/− mice compared with wild-type mice. The p38γ/δ−/− mice had lower levels of pathogenic anticollagen antibodies and interleukin-1β (IL-1β) and tumor necrosis factor α than controls. In vitro T cell assays showed reduced proliferation, interferon-γ (IFNγ) production, and IL-17 production by lymph node cells from p38γ/δ−/− mice. IL-17 and IFNγ messenger RNA expression in joints was significantly inhibited in p38γ/δ−/− mice. Wild-type chimeric mice with p38γ/δ−/− bone marrow did not show decreased CIA. Conclusion Reduced disease severity in p38γ/δ−/− mice was associated with lower cytokine production and anticollagen antibody responses than in controls, indicating that p38γ and p38δ are crucial regulators of inflammatory joint destruction in CIA. Our findings indicate that p38γ and p38δ are potential therapeutic targets in complex diseases, such as rheumatoid arthritis, that involve innate and adaptive immune responses.

Summary The aim of this study was to analyse the distribution of regulatory and inhibitory mothers against decapentaplegic homologue (Smad) proteins as markers of active transforming growth factor (TGF)-β signalling in rheumatoid arthritis (RA) synovial tissue and to investigate the effect of TGF-β blockade in the development and progression of collagen-induced arthritis. The expression of Smad proteins in synovial tissues from RA, osteoarthritic and healthy controls was analysed by immunohistochemistry. Arthritis was induced in DBA/1 mice by immunization with chicken type-II collagen (CII). TGF-β was blocked in vivo with the specific peptide p17 starting at the time of immunization or on the day of arthritis onset. T cell population frequencies and specific responses to CII were analysed. The expression of cytokines and transcription factors was quantified in spleen and joint samples. Statistical differences between groups were compared using the Mann–Whitney U-test or one-way analysis of variance (anova) using the Kruskal–Wallis test. p-Smad-2/3 and inhibitory Smad-7 expression were detected in RA and control tissues. In RA, most lymphoid infiltrating cells showed nuclear p-Smad-2/3 without Smad-7 expression. Treatment with TGF-β antagonist did not affect clinical severity, joint inflammation and cartilage damage in collagen-induced arthritis. Frequency of T cell subsets, mRNA levels of cytokines and transcription factors, specific proliferation to CII, serum interleukin (IL)-6 and anti-CII antibodies were comparable in p17 and phosphate-buffered saline (PBS)-treated groups. The pattern of Smad proteins expression demonstrates active TGF-β signalling in RA synovium. However, specific TGF-β blockade does not have a significant effect in the mice model of collagen-induced arthritis.

Objective CXCL12γ is an alternative splicing isoform of CXCL12 with enhanced affinity for heparan sulfate (HS) proteoglycans. This study was undertaken to investigate the distribution and potential function of CXCL12γ in rheumatoid arthritis (RA) synovium and normal lymphoid tissue, where its immobilization to HS may be relevant in pathologic or homeostatic immune cell migration and activation. Methods Expression of CXCL12 or CXCL12γ was immunodetected in RA and normal synovium, lymphoid tissue, and cultured cells with anti–pan-CXCL12 or anti-CXCL12γ–specific monoclonal antibodies. CXCL12α and CXCL12γ messenger RNA expression was analyzed by quantitative reverse transcription–polymerase chain reaction. Binding of wild-type CXCL12 isoforms or their HS binding–defective mutants to monocyte-derived dendritic cells (DCs) was analyzed by flow cytometry. The effect of DC-bound CXCL12α and CXCL12γ on T cell activation was analyzed in DC/T cell allogeneic cultures. Results CXCL12γ expression was increased in RA compared to normal synovium and preferentially located in endothelia and DC-SIGN–positive cells. This distribution was also observed in lymphoid organs. Surface-bound CXCL12γ was detected in a fraction of freshly isolated DCs. Monocyte-derived DCs, but not monocytes, showed a high capacity to bind CXCL12γ in an HS-dependent manner. Surface-bound CXCL12α and CXCL12γ on monocyte-derived DCs were potent inhibitors of allogeneic T cell activation, in contrast to the T cell–stimulatory effects of soluble CXCL12 proteins. Conclusion CXCL12γ shows a specific and similar distribution in RA synovium and lymphoid tissue, consistent with its higher HS binding affinity. Presentation of CXCL12 to T cells on membrane HS in DCs can play a distinct regulatory role in T cell activation.

The paradigm to explain antigen-dependent T cell receptor (TCR) signaling is based on the activation of the CD4 or CD8 coreceptor-associated kinase Lck. It is widely assumed that this paradigm is also applicable to signaling by bacterial superantigens. However, these bacterial toxins can activate human T cells lacking Lck, suggesting the existence of an additional pathway of TCR signaling. Here we showed that this alternative pathway operates in the absence of Lck-dependent tyrosine-phosphorylation events and was initiated by the TCR-dependent activation of raft-enriched heterotrimeric Galpha11 proteins. This event, in turn, activated a phospholipase C-beta and protein kinase C-mediated cascade that turned on the mitogen-activated protein kinases ERK-1 and ERK-2, triggered Ca(2+) influx, and translocated the transcription factors NF-AT and NF-kappaB to the nucleus, ultimately inducing the production of interleukin-2 in Lck-deficient T cells. The triggering of this alternative pathway by superantigens suggests that these toxins use a G protein-coupled receptor as a coreceptor on T cells.

Type II collagen-induced arthritis (CIA) is an animal model of rheumatoid arthritis that has been used extensively to address questions of disease pathogenesis and to validate novel therapeutic targets. Susceptibility to CIA is strongly associated with major histocompatibility complex class II genes, and the development of arthritis is accompanied by a robust T- and B-cell response to type II collagen. The main pathological features of CIA include proliferative synovitis with infiltration of inflammatory cells, pannus formation, cartilage degradation, erosion of bone and fibrosis. Pro-inflammatory cytokines, such as tumour necrosis factor alpha and interleukin-1beta, are expressed in the arthritic joints in both murine CIA and human rheumatoid arthritis, and blockade of these molecules results in amelioration of disease. Hence, there is a great deal of interest in the development of small-molecular-weight inhibitors of pro-inflammatory cytokines. There is also interest in the development and testing of drugs with the capacity to modulate the immune pathways involved in driving the inflammatory response in arthritis. For these reasons, there is a need to monitor the effect of novel treatments on cytokine expression in vivo. In this review, we outline the various techniques used to detect cytokines in experimental arthritis and describe how these techniques have been used to quantify changes in cytokine expression following therapeutic intervention.

Bacterial superantigens (SAgs) constitute a large family of bacterial toxins that share the capacity to induce massive activation of the human immune system. Such a feature is based on the ability of these toxins to activate T cells that express Beta-chains of the T cell antigen receptor (TCR) containing variable regions (V) coded by specific families of VBeta genes. In addition, bacterial SAgs bypass the need for processing by antigen-presenting cells by directly binding to major histocompatibility complex class II molecules on the surface of these cells. Emerging work indicates that bacterial SAgs utilize not only the canonical pathways of TCR-mediated T cell activation but also other pathways. Here, we review the structural information on recognition of bacterial SAgs by T cells, the TCR signalling induced by this recognition event, and the effector functions that this recognition triggers. We analyze experimental evidence suggesting the existence of alternative receptors and coreceptors for bacterial SAgs, and outline future challenges in the research with these toxins.

Background CD271+ stromal cells (SCs) with multipotent stem cell capacity have been identified in synovial tissues, but their functional significance is unknown. We analyzed the distribution of CD271+ cells in inflammatory synovial tissues as well as their ex vivo immunomodulatory and inflammatory phenotypes. Methods CD271 expression was analyzed by immunohistochemistry in synovial tissues and by flow cytometry in primary adherent synovial cell cultures from rheumatoid arthritis (RA), osteoarthritis (OA), and non-inflammatory control tissues. Isolation of CD271+ synovial SCs was carried out by magnetic cell sorting. Allogeneic T-cell/SC cocultures were performed to analyze the regulatory capacity of these cells on T-cell proliferation and cytokine production. The production of inflammatory mediators was analyzed in cultures of sorted CD271+/− SCs. The capacity of CD271+/− SCs to induce inflammatory cell recruitment in vivo was evaluated in subcutaneous implants in immunodeficient mice. Results CD271+ SC were detected in non-inflammatory as well as in arthritic synovial tissues with a specific perivascular distribution. CD271+ SC density was increased in RA and OA compared with normal synovial tissues. T-cell proliferation and cytokine synthesis were similarly modified by CD271+ and CD271− SCs. Sorted CD271+ SCs from OA synovial tissues released significantly more interleukin (IL)-6, matrix metalloproteinase (MMP)-1, and MMP-3 than CD271− SCs. In immunodeficient mice, implants of CD271+ SCs induced significantly higher myeloid cell infiltration than CD271− SCs. Conclusions Our results demonstrate that CD271+ perivascular SCs expand in RA and OA synovial tissues. CD271+ cells showed enhanced proinflammatory properties ex vivo and in vivo, whereas immunoregulatory properties were equivalent in CD271+ and CD271− SC. Electronic supplementary material The online version of this article (doi:10.1186/s13075-016-0966-5) contains supplementary material, which is available to authorized users.