CXCR3 and CCR5 ligands in rheumatoid arthritis synovium

Cytokine profiles associated with disease severity and prognosis of autoimmune pulmonary alveolar proteinosis

BACKGROUND

Pulmonary alveolar proteinosis (PAP) is characterized by an abnormal accumulation of surfactants in the alveoli. Most cases are classified as autoimmune PAP (APAP) because they are associated with autoantibodies against granulocyte-macrophage colony-stimulating factor (GM-CSF). However, GM-CSF autoantibody levels are unlikely to correlate with the disease severity or prognosis of APAP.

METHODS

We collected clinical records and measured 38 serum cytokine concentrations for consecutive patients with APAP. After exclusion of 21 cytokines because of undetectable levels, 17 cytokine levels were compared between low and high disease severity scores (DSSs). We also compared whole lung lavage (WLL)-free survival with cut-off values defined by receiver operating characteristic (ROC) curves of cytokine levels and WLL administration at 11 months.

RESULTS

Nineteen patients with APAP were enrolled in the study. Five were classified as DSS 1 or 2, while the others were classified as DSS 4 or 5. Comparison between DSS 1-2 and 4-5 revealed that the concentrations of IP-10 and GRO increased in the latter groups (p < 0.05). Fifteen patients underwent WLL. Comparison between those who underwent WLL within 11 months and the others showed that IP-10 and TNF-α were tended to be elevated in the former group (p = 0.082 and 0.057, respectively). The cut-off values of IP-10, 308.8 pg/mL and TNF-α, 19.1 pg/mL, defined by the ROC curves, significantly separated WLL-free survivals with log-rank analyses (p = 0.005).

CONCLUSIONS

The concentrations of IP-10 and GRO may reflect the DSSs of APAP. A combination of IP-10 and TNF-α levels could be a biomarker to predict WLL-free survival.

Modulation of plasmacytoid dendritic cells response in inflammation and autoimmunity

The discovery of toll-like receptors (TLRs) and the subsequent recognition that endogenous nucleic acids (NAs) could serve as TLR ligands have led to essential insights into mechanisms of healthy immune responses as well as pathogenic mechanisms relevant to systemic autoimmune and inflammatory diseases. In systemic lupus erythematosus, systemic sclerosis, and rheumatoid arthritis, NA-containing immune complexes serve as TLR ligands, with distinct implications depending on the additional immune stimuli available. Plasmacytoid dendritic cells (pDCs), the robust producers of type I interferon (IFN-I), are providing critical insights relevant to TLR-mediated healthy immune responses and tissue repair, as well as generation of inflammation, autoimmunity and fibrosis, processes central to the pathogenesis of many autoimmune diseases. In this review, we describe recent data characterizing the role of platelets and NA-binding chemokines in modulation of TLR signaling in pDCs, as well as implications for how the IFN-I products of pDCs contribute to the generation of inflammation and wound healing responses by monocyte/macrophages. Chemokine modulators of TLR-mediated B cell tolerance mechanisms and interactions between TLR signaling and metabolic pathways are also considered. The modulators of TLR signaling and their contribution to the pathogenesis of systemic autoimmune diseases suggest new opportunities for identification of novel therapeutic targets.

Piperine suppresses inflammatory fibroblast-like synoviocytes derived from rheumatoid arthritis patients Via NF-κB inhibition

Rheumatoid Arthritis (RA) is a common autoimmune disease recognized by hyperplasia of synoviocytes and chronic joint inflammation. Activation of fibroblast-like synoviocytes (FLSs) is one of the main features of RA which can trigger inflammation leading to articular cartilage and joint destruction. Aberrant activation of NF-κB signaling cascade was found to be responsible for the high proliferation and defective apoptosis of FLSs and subsequent inflammation in RA. Piperine is a principal constituent of piper species frequently used as antitumor and anti-inflammatory natural compound. In this study we aimed to assess the anti-inflammatory effect of piperine on RA-FLS through NF-κB inhibition. FLSs were isolated from 68 RA patients and 30 healthy controls and were exposed to piperine. The main assays were MTT assay, flow cytometric analysis, PI staining, reverse transcription-PCR (RT-PCR), and ELISA. Results showed that piperine can induce the apoptosis and reduce the proliferation of RA-FLSs in vitro. Moreover, piperine directly reduced the phosphorylation of NF-kB and the expression of NF-κB target genes related to RA-FLSs proliferation (c-Myc and Cycline D1), apoptosis inhibition (Bcl2 and Bcl-xl) and inflammation (COX2, IL-1β, TNF-α,IL-6, CCL5 and CXCL10) while increasing the expression of apoptosis related ones (Bax) in vitro. Piperine also reduced the protein levels of cytokines and chemokines secreted by FLSs as a result of NF-κB inhibition. In conclusion, our results provide evidence for the anti-inflammatory capacity of piperine through inhibition of NF-κB pathway in FLSs proposing this compound as a suitable alternative for chemical treatment of RA.

The Fidelity of Rheumatoid Arthritis Multivariate Diagnostic Biomarkers Using Discriminant Analysis and Binary Logistic Regression

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease that causes multi-articular synovitis. The illness is characterized by worsening inflammatory synovitis, which causes joint swelling and pain. Synovitis erodes articular cartilage and marginal bone, resulting in joint deterioration. This bone injury is expected to be permanent. Cytokines play a prominent role in the etiology of RA and could be useful as early diagnostic biomarkers. This research was carried out at Riyadh's King Khalid University Hospital (KKUH). Patients were enrolled from the Rheumatology unit. Seventy-eight RA patients were recruited (67 (85.9%) females and 11 (14.1%) males). Patients were selected for participation by convenience sampling. Demographic data were collected, and disease activity measurements at 28 joints were recorded using the disease activity score (DAS-28). Age- and sex-matched controls from the general population were included in the study. A panel of 27 cytokines, chemokines, and growth factors was determined in patient and control sera. Binary logistic regression (BLR) and discriminant analysis (DA) were used to analyze the data. We show that multiple cytokine biomarker profiles successfully distinguished RA patients from healthy controls. IL-17, IL-4, and RANTES were among the most predictive variables and were the only biomarkers incorporated into both BLR and DA predictive models for pooled participants (men and women). In the women-only models, the significant cytokines incorporated in the model were IL-4, IL-17, MIP-1b, and RANTES for the BLR model and IL-4, IL-1Ra, GM-CSF, IL-17, and eotaxin for the DA model. The BLR and DA men-only models contained one cytokine each, eotaxin for BLR and platelet-derived growth factor-bb (PDGF-BB) for DA. We show that BLR has a higher fidelity in identifying RA patients than DA. We also found that the use of gender-specific models marginally improves detection fidelity, indicating a possible benefit in clinical diagnosis. More research is needed to determine whether this conclusion will hold true in various and larger patient populations.

Hydroxychloroquine reduces T cells activation recall antigen responses

BACKGROUND

In the context of the current COVID-19 pandemic, there is still limited information about how people suffering from autoimmune diseases respond to the different COVID vaccines. The fact that they are taking an immunosuppressant or other drugs that aim to decrease the immune system activities, such as hydroxychloroquine (HCQ), could also impact their ability to respond to a COVID vaccine and vaccines in general.

METHODS

Heathy donors were given 200mg of HCQ daily for 6-weeks to assess HCQs impact on the systemic T cells and humoral immune response. Peripheral blood mononuclear cells (PBMC) and plasma were obtained at baseline and 6-weeks after starting daily HCQ. Flow cytometry assays were designed to determine changes in T cell activation and T cell responses. Bead array multiplex were used to analyse antibodies and cytokine levels before and after HCQ intake.

RESULTS

As anticipated, HCQ treatment decreased ex vivo T cell activation. We observed a decrease in CD4+CD161- expressing CCR5 (p = 0.015) and CD69 (p = 0.004) as well as in CD8+CCR5+ (p = 0.003), CD8+CD161+CCR5+ (p = 0.002) and CD8+CD161+CD95+ (p = 0.004). Additionally, HCQ decreased the proportion of Th17 expressing CD29 (p = 0.019), a subset associated with persistent inflammation. The proportion of T regulatory cells expressing the inhibitory molecule TIGIT was also reduced by HCQ (p = 0.003). As well, T cells from people on HCQ were less responsive to activation and cytokine production following stimulation with recall antigens and memory T cells were less likely to produce both IFNγ and TNFα following stimulation.

CONCLUSION

This study shows HCQ is associated with lower T cell activation and decreased T cell cytokine production. While this study was not performed with the intent of looking at COVID vaccine response, it does provide important information about the changes in immune response that may occur in patient taking HCQ as a treatment for their autoimmune disease.

Equine Polyclonal Antibodies Prevent Acute Chikungunya Virus Infection in Mice

Chikungunya virus (CHIKV) is a mosquito-transmitted pathogen that causes chikungunya disease (CHIK); the disease is characterized by fever, muscle ache, rash, and arthralgia. This arthralgia can be debilitating and long-lasting, seriously impacting quality of life for years. Currently, there is no specific therapy available for CHIKV infection. We have developed a despeciated equine polyclonal antibody (CHIKV-EIG) treatment against CHIKV and evaluated its protective efficacy in mouse models of CHIKV infection. In immunocompromised (IFNAR^-/-) mice infected with CHIKV, daily treatment for five consecutive days with CHIKV-EIG administered at 100 mg/kg starting on the day of infection prevented mortality, reduced viremia, and improved clinical condition as measured by body weight loss. These beneficial effects were seen even when treatment was delayed to 1 day after infection. In immunocompetent mice, CHIKV-EIG treatment reduced virus induced arthritis (including footpad swelling), arthralgia-associated cytokines, viremia, and tissue virus loads in a dose-dependent fashion. Collectively, these results suggest that CHIKV-EIG is effective at preventing CHIK and could be a viable candidate for further development as a treatment for human disease.

CXCL10 as a shared specific marker in rheumatoid arthritis and inflammatory bowel disease and a clue involved in the mechanism of intestinal flora in rheumatoid arthritis

This study aimed to identify shared specific genes associated with rheumatoid arthritis (RA) and inflammatory bowel disease (IBD) through bioinformatic analysis and to examine the role of the gut microbiome in RA. The data were extracted from the 3 RA and 1 IBD gene expression datasets and 1 RA gut microbiome metagenomic dataset. Weighted correlation network analysis (WGCNA) and machine learnings was performed to identify candidate genes associated with RA and IBD. Differential analysis and two different machine learning algorithms were used to investigate RA's gut microbiome characteristics. Subsequently, the shared specific genes related to the gut microbiome in RA were identified, and an interaction network was constructed utilizing the gutMGene, STITCH, and STRING databases. We identified 15 candidates shared genes through a joint analysis of the WGCNA for RA and IBD. The candidate gene CXCL10 was identified as the shared hub gene by the interaction network analysis of the corresponding WGCNA module gene to each disease, and CXCL10 was further identified as the shared specific gene by two machine learning algorithms. Additionally, we identified 3 RA-associated characteristic intestinal flora (Prevotella, Ruminococcus, and Ruminococcus bromii) and built a network of interactions between the microbiomes, genes, and pathways. Finally, it was discovered that the gene CXCL10 shared between IBD and RA was associated with the three gut microbiomes mentioned above. This study demonstrates the relationship between RA and IBD and provides a reference for research into the role of the gut microbiome in RA.

CXCR3 antagonist NBI-74330 mitigates joint inflammation in Collagen-Induced arthritis model in DBA/1J mice

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by uncontrolled synovial proliferation, pannus formation, cartilage injury, and bone destruction. We used the CXCR3-specific antagonist NBI-74330 to block T-cell-mediated signaling in a DBA/1J mouse model of collagen-induced arthritis (CIA). After CIA induction, DBA/1J mice were treated with NBI-74330 (100 mg/kg) daily from day 21 until day 34 and evaluated for arthritic score and histopathological changes. Furthermore, using flow cytometry, we investigated the effects of NBI-74330 on Th1 (IFN-γ, TNF-α, T-bet, STAT4, Notch-3, and RANKL), Th17 (IL-21, IL-17A, STAT3, and RORγt), and Th22 (IL-22) cells in splenic CD4⁺ and CXCR3⁺T-cells. We also used RT-PCR to assess the effect of mRNA levels of IFN-γ, TNF-α, T-bet, RANKL, IL-17A, RORγt, and IL-22 in knee tissues. The IFN-γ, TNF-α, and IL-17A serum protein levels were measured using ELISA. Compared to vehicle-treated CIA mice, the severity of arthritic scores and histological severity of inflammation decreased significantly in NBI-74330-treated CIA mice. Moreover, compared to vehicle-treated CIA mice, the percentages of CD4⁺IFN-γ⁺, CD4⁺TNF-α⁺, CD4⁺T-bet⁺, CD4⁺STAT4⁺, CD4⁺Notch-3⁺, CXCR3⁺IFN-γ⁺, CXCR3⁺TNF-α⁺, CXCR3⁺T-bet⁺, CXCR3⁺STAT4⁺, CXCR3⁺Notch-3⁺, CD4⁺RANKL⁺, CD4⁺IL-21⁺, CD4⁺IL-17A⁺, CD4⁺STAT3⁺, CD4⁺RORγt⁺, and CD4⁺IL-22⁺ cells decreased in NBI-74330-treated CIA mice. Furthermore, NBI-74330-treatment downregulated IFN-γ, TNF-α, T-bet, RANKL, STAT3, IL-17A, RORγt, and IL-22 mRNA levels. Serum IFN-γ, TNF-α, and IL-17A levels were significantly lower in NBI-74330-treated CIA mice than in vehicle-treated CIA mice. This study demonstrates the antiarthritic effects of NBI-74330 in CIA mice. Therefore, these data suggest that NBI-74330 could be considered a potential RA treatment.

A review of the pleiotropic actions of the IFN-inducible CXC chemokine receptor 3 ligands in the synovial microenvironment

Chemokines are pivotal players in instigation and perpetuation of synovitis through leukocytes egress from the blood circulation into the inflamed articulation. Multitudinous literature addressing the involvement of the dual-function interferon (IFN)-inducible chemokines CXCL9, CXCL10 and CXCL11 in diseases characterized by chronic inflammatory arthritis emphasizes the need for detangling their etiopathological relevance. Through interaction with their mutual receptor CXC chemokine receptor 3 (CXCR3), the chemokines CXCL9, CXCL10 and CXCL11 exert their hallmark function of coordinating directional trafficking of CD4+ TH1 cells, CD8+ T cells, NK cells and NKT cells towards inflammatory niches. Among other (patho)physiological processes including infection, cancer, and angiostasis, IFN-inducible CXCR3 ligands have been implicated in autoinflammatory and autoimmune diseases. This review presents a comprehensive overview of the abundant presence of IFN-induced CXCR3 ligands in bodily fluids of patients with inflammatory arthritis, the outcomes of their selective depletion in rodent models, and the attempts at developing candidate drugs targeting the CXCR3 chemokine system. We further propose that the involvement of the CXCR3 binding chemokines in synovitis and joint remodeling encompasses more than solely the directional ingress of CXCR3-expressing leukocytes. The pleotropic actions of the IFN-inducible CXCR3 ligands in the synovial niche reiteratively illustrate the extensive complexity of the CXCR3 chemokine network, which is based on the intercommunion of IFN-inducible CXCR3 ligands with distinct CXCR3 isoforms, enzymes, cytokines, and infiltrated and resident cells present in the inflamed joints.

Involvement of chemokine receptor CXCR3 in the defense mechanism against Neospora caninum infection in C57BL/6 mice

C-X-C motif chemokine receptor 3 (CXCR3) is an important receptor controlling the migration of leukocytes, although there is no report regarding its role in Neospora caninum infection. Herein, we investigated the relevance of CXCR3 in the resistance mechanism to N. caninum infection in mice. Wild-type (WT) C57BL/6 mice and CXCR3-knockout (CXCR3KO) mice were used in all experiments. WT mice displayed a high survival rate (100%), while 80% of CXCR3KO mice succumbed to N. caninum infection within 50 days. Compared with WT mice, CXCR3KO mice exhibited significantly lower body weights and higher clinical scores at the subacute stage of infection. Flow cytometric analysis revealed CXCR3KO mice as having significantly increased proportions and numbers of CD11c-positive cells compared with WT mice at 5 days post infection (dpi). However, levels of interleukin-6 and interferon-γ in serum and ascites were similar in all groups at 5 dpi. Furthermore, no differences in parasite load were detected in brain, spleen, lungs or liver tissue of CXCR3KO and WT mice at 5 and 21 dpi. mRNA analysis of brain tissue collected from infected mice at 30 dpi revealed no changes in expression levels of inflammatory response genes. Nevertheless, the brain tissue of infected CXCR3KO mice displayed significant necrosis and microglial activation compared with that of WT mice at 21 dpi. Interestingly, the brain tissue of CXCR3KO mice displayed significantly lower numbers of FoxP3⁺ cells compared with the brain tissue of WT mice at 30 dpi. Accordingly, our study suggests that the lack of active regulatory T cells in brain tissue of infected CXCR3KO mice is the main cause of these mice having severe necrosis and lower survival compared with WT mice. Thus, CXCR3⁺ regulatory T cells may play a crucial role in control of neosporosis.

Chemokines and chemokine receptors as promising targets in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease that commonly causes inflammation and bone destruction in multiple joints. Inflammatory cytokines, such as IL-6 and TNF-α, play important roles in RA development and pathogenesis. Biological therapies targeting these cytokines have revolutionized RA therapy. However, approximately 50% of the patients are non-responders to these therapies. Therefore, there is an ongoing need to identify new therapeutic targets and therapies for patients with RA. In this review, we focus on the pathogenic roles of chemokines and their G-protein-coupled receptors (GPCRs) in RA. Inflamed tissues in RA, such as the synovium, highly express various chemokines to promote leukocyte migration, tightly controlled by chemokine ligand-receptor interactions. Because the inhibition of these signaling pathways results in inflammatory response regulation, chemokines and their receptors could be promising targets for RA therapy. The blockade of various chemokines and/or their receptors has yielded prospective results in preclinical trials using animal models of inflammatory arthritis. However, some of these strategies have failed in clinical trials. Nonetheless, some blockades showed promising results in early-phase clinical trials, suggesting that chemokine ligand-receptor interactions remain a promising therapeutic target for RA and other autoimmune diseases.

MAPK activated kinase 2 inhibition shifts the chemokine signature in arthritis synovial fluid mononuclear cells from CXCR3 to CXCR2

BACKGROUND

The development of novel treatment strategies of immune-mediated inflammatory arthritis (IMIA) is still a clinical unmet need. The mitogen-activated protein kinase (MAPK) pathway is activated by environmental stressors, growth factors and inflammatory cytokines. However, the inhibition of central MAPK proteins has so far had undesirable side effects. The MAPK-activated protein kinase 2 (MK2) is a downstream mediator in the MAPK signaling pathway.

OBJECTIVES

The objective of this study was to explore the effects of a small molecule inhibiting MK2 on synovial fluid mononuclear cells from patients with IMIA.

METHODS

Synovial fluid mononuclear cells (SFMCs) were obtained from a study population consisting of patients with active rheumatoid arthritis (RA), peripheral spondyloarthritis (SpA) or psoriatic arthritis (PsA) with at least one swollen joint (for obtaining synovial fluid) (n = 11). SFMCs were cultured for 48 h with and without the MK2 inhibitor CC0786512 at 1000 nM, 333 nM and 111 nMand cell free supernatants were harvested and frozen before they were analyzed by the Olink proseek multiplex interferon panel.

RESULTS

In SFMCs cultured for 48 h, the MK2 inhibitor decreased the production of chemokine (C-X-C motif) ligand 9 (CXCL9) (P < 0.001), CXCL10 (P < 0.01), hepatocyte growth factor (HGF) (P < 0.01), CXCL11 (P < 0.01), tumor necrosisfactor-like weak inducer of apoptosis (TWEAK) (P < 0.05), and interleukin 12B (IL-12B) (P < 0.05) and increased the production of CXCL5 (P < 0.0001), CXCL1 (P < 0.0001), CXCL6 (P < 0.001), transforming growthfactoralpha (TGFα) (P = 0.01), monocyte-chemotactic protein 3 (MCP-3) (P < 0.01), latency-associated peptide (LAP) TGFβ (P < 0.05) dose-dependently.

CONCLUSIONS

This study reveals the downstream effects of MK2 inhibition on the secretory profile of SFMCs. Specifically, C-X-C motif chemokine receptors 3 (CXCR3) chemokines were decreased and CXCR2 chemokines were increased. This shift in the chemokine milieu may be one of the mechanisms behind the anti-inflammatory effects of MK2 inhibitors.

RNA-seq and Network Analysis Reveal Unique Chemokine Activity Signatures in the Synovial Tissue of Patients With Rheumatoid Arthritis

Purpose

This study aimed to provide a comprehensive understanding of the genome-wide expression patterns in the synovial tissue samples of patients with rheumatoid arthritis (RA) to investigate the potential mechanisms regulating RA occurrence and development.

Methods

Transcription profiles of the synovial tissue samples from nine patients with RA and 15 patients with osteoarthritis (OA) (control) from the East Asian population were generated using RNA sequencing (RNA-seq). Gene set enrichment analysis (GSEA) was used to analyze all the detected genes and the differentially expressed genes (DEGs) were identified using DESeq. To further analyze the DEGs, the Gene Ontology (GO) functional enrichment and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed. The protein-protein interaction (PPI) network of the DEGs was constructed using the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) and the hub genes were identified by topology clustering with the Molecular Complex Detection (MCODE)-Cytoscape. The most important hub genes were validated using quantitative real-time PCR (qRT-PCR).

Results

Of the 17,736 genes detected, 851 genes were identified as the DEGs (474 upregulated and 377 downregulated genes) using the false discovery rate (FDR) approach. GSEA revealed that the significantly enriched gene sets that positively correlated with RA were CD40 signaling overactivation, Th1 cytotoxic module, overactivation of the immune response, adaptive immune response, effective vs. memory CD8+ T cells (upregulated), and naïve vs. effective CD8+ T cells (downregulated). Biological process enrichment analysis showed that the DEGs were significantly enriched for signal transduction (P = 3.01 × 10-6), immune response (P = 1.65 × 10-24), and inflammatory response (P = 5.76 × 10-10). Molecule function enrichment analysis revealed that the DEGs were enriched in calcium ion binding (P = 1.26 × 10-5), receptor binding (P = 1.26 × 10-5), and cytokine activity (P = 2.01 × 10-3). Cellular component enrichment analysis revealed that the DEGs were significantly enriched in the plasma membrane (P = 1.91 × 10-31), an integral component of the membrane (P = 7.39 × 10-13), and extracellular region (P = 7.63 × 10-11). The KEGG pathway analysis showed that the DEGs were enriched in the cytokine-cytokine receptor interaction (P = 3.05 × 10-17), chemokine signaling (P = 3.50 × 10-7), T-cell receptor signaling (P = 5.17 × 10-4), and RA (P = 5.17 × 10-4) pathways. We confirmed that RA was correlated with the upregulation of the PPI network hub genes, such as CXCL13, CXCL6, CCR5, CXCR5, CCR2, CXCL3, and CXCL10, and the downregulation of the PPI network hub gene such as SSTR1.

Conclusion

This study identified and validated the DEGs in the synovial tissue samples of patients with RA, which highlighted the activity of a subset of chemokine genes, thereby providing novel insights into the molecular mechanisms of RA pathogenesis and identifying potential diagnostic and therapeutic targets for RA.

The Effect of α7nAChR Signaling on T Cells and Macrophages and Their Clinical Implication in the Treatment of Rheumatic Diseases

Rheumatoid arthritis (RA) is one of the most common autoimmune disease and until now, the etiology and pathogenesis of RA is not fully understood, although dysregulation of immune cells is one of the leading cause of RA-related pathological changes. Based on current understanding, the priority of anti-rheumatic treatments is to restore immune homeostasis. There are several anti-rheumatic drugs with immunomodulatory effects available nowadays, but most of them have obvious safety or efficacy shortcomings. Therefore, the development of novel anti-rheumatic drugs is still in urgently needed. Cholinergic anti-inflammatory pathway (CAP) has been identified as an important aspect of the so-called neuro-immune regulation feedback, and the interaction between acetylcholine and alpha 7 nicotinic acetylcholine receptor (α7nAChR) serves as the foundation for this signaling. Consistent to its immunomodulatory functions, α7nAChR is extensively expressed by immune cells. Accordingly, CAP activation greatly affects the differentiation and function of α7nAChR-expressing immune cells. As a result, targeting α7nAChR will bring profound therapeutic impacts on the treatment of inflammatory diseases like RA. RA is widely recognized as a CD4+ T cells-driven disease. As a major component of innate immunity, macrophages also significantly contribute to RA-related immune abnormalities. Theoretically, manipulation of CAP in immune cells is a feasible way to treat RA. In this review, we summarized the roles of different T cells and macrophages subsets in the occurrence and progression of RA, and highlighted the immune consequences of CAP activation in these cells under RA circumstances. The in-depth discussion is supposed to inspire the development of novel cell-specific CAP-targeting anti-rheumatic regimens.

Shoulder Lesions Do Not Increase Inflammatory Biomarkers in Patients Undergoing Surgery for Glenohumeral Instability: An Exploratory Study

Circulating protein biomarkers have demonstrated utility as a diagnostic tool in predicting musculoskeletal disease severity, but their utility in the evaluation of shoulder lesions associated with shoulder instability is unknown. Thus, the purpose of this exploratory study was to determine whether preoperative biomarkers of cartilage turnover and inflammation are associated with specific shoulder lesions in shoulder instability. Thirty-three patients (29.9 ± 9.4 years of age, 4.5 ± 4.7 dislocations) undergoing surgical treatment for shoulder instability were assessed for the presence or absence of associated shoulder lesions. Biomarkers including cartilage oligomeric matrix protein (COMP), C-reactive protein (HS-CRP), interleukin-8 (IL-8), and macrophage inflammatory protein-1β (MIP-1b) were collected at the time of surgery. Patients with Hill-Sachs lesions had a 31% increase in COMP plasma levels (p=0.046). No other significant differences were observed for COMP, HS-CRP, IL-8, and MIP-1b with any shoulder lesion including Hill-Sachs lesions, capsular injuries, bony Bankart lesions, and SLAP lesions. In conclusion, inflammatory biomarkers including HS-CRP, IL-8, and MIP-1b were not associated with specific shoulder lesions, while biomarkers of cartilage turnover (COMP) were only elevated in Hill-Sachs lesions. These findings suggest that these biomarkers may have limited utility as prognostic indicators in patients with shoulder instability, though large-scale and longitudinal studies are still necessary.

Genetically Determined Circulating Levels of Cytokines and the Risk of Rheumatoid Arthritis

Background: Accumulation of inflammatory leukocytes in articular tissues is the hallmark feature of rheumatoid arthritis (RA). Increasing evidence from observational studies has suggested that several cytokines may be involved in the development of RA. However, traditional observational studies are susceptible to bias from confounding and reverse causation; therefore, the potential causal relationships of individual cytokines with the risk of RA remain elusive.

Objective: In this study, we evaluated whether genetically determined circulating levels of cytokines were associated with the risk of RA by performing Mendelian randomization (MR).

Methods: We identified single nucleotide polymorphisms (SNPs) associated with circulating levels of cytokines and growth factors from a genome-wide association study (GWAS) including 8,293 participants of Finnish ancestry as instrumental variables (IVs). The association estimates of these IVs with the risk of RA were obtained from a GWAS meta-analysis including 14,361 RA cases and 43,923 controls of European ancestry. We conducted a series of MR analyses to assess the relationship between genetically determined circulating cytokines and the risk of RA, including the random-effects inverse variance-weighted, weighted-median, MR-Egger regression, and MR pleiotropy residual sum and outlier tests. For potential cytokine-RA associations supported by MR evidence, sensitivity analyses were further performed using restricted IV sets of SNPs with colocalization evidence and that excluding pleiotropic SNPs.

Results: In the primary MR analysis, there was a suggestive inverse association between genetically determined circulating level of macrophage inflammatory protein-1β (MIP-1b) and the risk of RA [odds ratio (OR): 0.95, 95% confidence interval (CI) = 0.92-0.99, p = 0.016]. The effect estimates were similar in alternative MR analyses. Among SNPs used as IVs for MIP-1b, we found 92 SNPs without documented pleiotropy and three SNPs with evidence of colocalization. The association of MIP-1b with RA from sensitivity analyses using these two sets of restricted IVs remained stable.

Conclusion: Our study suggests that genetically determined elevated circulating level of MIP-1b may be associated with a lower risk of RA. Further studies are warranted to determine how MIP-1b and related pathways may contribute to the development of RA.

Patterns of T-Cell Phenotypes in Rheumatic Diseases From Single-Cell Studies of Tissue

High-dimensional analyses of tissue samples from patients with rheumatic diseases are providing increasingly detailed descriptions of the immune cell populations that infiltrate tissues in different rheumatic diseases. Here we review key observations emerging from high-dimensional analyses of T cells within tissues in different rheumatic diseases, highlighting common themes across diseases as well as distinguishing features. Single-cell RNA sequencing analyses capture several dimensions of T-cell states, yet surprisingly, these analyses generally have not demonstrated distinct clusters of paradigmatic T-cell effector subsets, such as T helper (Th) 1, Th2, and Th17 cells. Rather, global transcriptomics robustly identify both proliferating T cells and regulatory T cells and have also helped to reveal new effector subsets in inflamed tissues, including T peripheral helper cells and granzyme K⁺ T cells. Further characterization of the T-cell populations that accumulate within target tissues should enable more precise targeting of biologic therapies and accelerate development of more specific biomarkers to track activity of relevant immune pathways in patients with rheumatic diseases.

Efficacy of novel bispecific antibody targeting TNF-α/CXCL10 in the treatment of experimental arthritis

This study was aimed at generating and investigating the efficacy of a novel monoclonal bispecific antibody (BsAb) for the combined inhibition of tumor necrosis factor-α (TNF-α) and CXCL10 as a treatment option for rheumatoid arthritis (RA). A novel BsAb targeting TNF-α and CXCL10 was generated by conjugating a single-chain variable fragment (scFv) of the anti-CXCL10 monoclonal antibody to the Fc region of adalimumab (ADA). The effects of the BsAb on the inflammatory response in the in vitro and in vivo development of arthritis and joint destruction were evaluated in human TNF transgenic (hTNF-Tg) mice, and K/BxN serum transfer arthritis models. The BsAb inhibited CXCL10-mediated CD8⁺ T cell migration. The binding affinity of the BsAb to TNF-α was comparable to that of ADA and suppressed TNF-α induced cell death and inhibited TNF-α induced ICAM-1 and VCAM-1 in RA fibroblast-like synoviocytes (FLSs). The BsAb decreased the expression of TNFSF11 and the production of IL-6 in RA-FLS cells stimulated with TNF-α and CXCL10. Treatment with the BsAb attenuated the development of arthritis in hTNF-Tg mice and suppressed LPS-induced bone erosion. In the K/BxN serum transfer model, BsAb effectively attenuated ankle swelling, synovial inflammation, cartilage damage, and bone destruction, reducing the activation of osteoclasts. The additional neutralization of TNF-α and CXCL10 from treatment with the novel BsAb was more effective than TNF-α inhibition alone in the in vitro and in vivo models of RA. Thus, the BsAb, targeting both TNF-α and CXCL10, may provide a new therapeutic opportunity for RA patients who fail to respond to the blockade of a single cytokine.

Chemokine Receptor 5 Antagonism Causes Reduction in Joint Inflammation in a Collagen-Induced Arthritis Mouse Model

Rheumatoid arthritis (RA) is a chronic inflammatory disease mainly affecting the synovial joints. A highly potent antagonist of C-C chemokine receptor 5 (CCR5), maraviroc (MVC), plays an essential role in treating several infectious diseases but has not yet been evaluated for its potential effects on RA development. This study focused on evaluating the therapeutic potential of MVC on collagen-induced arthritis (CIA) in DBA/1J mice. Following CIA induction, animals were treated intraperitoneally with MVC (50 mg/kg) daily from day 21 until day 35 and evaluated for clinical score and histopathological changes in arthritic inflammation. We further investigated the effect of MVC on Th9 (IL-9, IRF-4, and GATA3) and Th17 (IL-21R, IL-17A, and RORγT) cells, TNF-α, and RANTES in CD8+ T cells in the spleen using flow cytometry. We also assessed the effect of MVC on mRNA and protein levels of IL-9, IL-17A, RORγT, and GATA3 in knee tissues using RT-PCR and western blot analysis. MVC treatment in CIA mice attenuated the clinical and histological severity of inflammatory arthritis, and it substantially decreased IL-9, IRF4, IL-21R, IL-17A, RORγT, TNF-α, and RANTES production but increased GATA3 production in CD8+ T cells. We further observed that MVC treatment decreased IL-9, IL-17A, and RORγt mRNA and protein levels and increased those of GATA3. This study elucidates the capacity of MVC to ameliorate the clinical and histological signs of CIA by reducing pro-inflammatory responses, suggesting that MVC may have novel therapeutic uses in the treatment of RA.

Shared recognition of citrullinated tenascin-C peptides by T and B cells in rheumatoid arthritis

Tenascin-C (TNC), an extracellular matrix protein that has proinflammatory properties, is a recently described antibody target in rheumatoid arthritis (RA). In this study, we utilized a systematic discovery process and identified 5 potentially novel citrullinated TNC (cit-TNC) T cell epitopes. CD4⁺ T cells specific for these epitopes were elevated in the peripheral blood of subjects with RA and showed signs of activation. Cit-TNC–specific T cells were also present among synovial fluid T cells and secreted IFN-γ. Two of these cit-TNC T cell epitopes were also recognized by antibodies within the serum and synovial fluid of individuals with RA. Detectable serum levels of cit-TNC–reactive antibodies were prevalent among subjects with RA and positively associated with cyclic citrullinated peptide (CCP) reactivity and the HLA shared epitope. Furthermore, cit-TNC–reactive antibodies were correlated with rheumatoid factor and elevated in subjects with a history of smoking. This work confirms cit-TNC as an autoantigen that is targeted by autoreactive CD4⁺ T cells and autoantibodies in patients with RA. Furthermore, our findings raise the possibility that coinciding epitopes recognized by both CD4⁺ T cells and B cells have the potential to amplify autoimmunity and promote the development and progression of RA.

C-C chemokine receptor 5 signaling contributes to cardiac remodeling and dysfunction under pressure overload

Aortic stenosis (AS) leads to chronic pressure overload, cardiac remodeling and eventually heart failure. Chemokines and their receptors have been implicated in pressure overload‑induced cardiac remodeling and dysfunction. In the present study, the role of C‑C chemokine receptor 5 (CCR5) in pressure overload‑induced cardiac remodeling and dysfunction was investigated in mice subjected to transverse aortic constriction (TAC). Cardiac levels of CCR5 and C‑C motif chemokine ligands (CCLs)3, 4 and 5 were determined by western blotting and reverse transcription‑quantitative PCR, respectively. Cardiac functional parameters were evaluated by echocardiographic and hemodynamic measurements. Myocardial fibrosis was assessed by Masson's trichrome staining and α‑smooth muscle actin immunostaining. Myocardial hypertrophy and inflammatory cell infiltration were evaluated by hematoxylin and eosin staining. Angiotensin II (Ang II)‑induced hypertrophy of H9c2 cardiomyocytes was assessed by F‑actin immunostaining. ERK1/2 and P38 phosphorylation was examined by western blotting. TAC mice exhibited higher myocardial CCL3, CCL4, CCL5 and CCR5 levels compared with sham mice. Compared with sham mice, TAC mice also exhibited impaired cardiac function along with myocardial hypertrophy, fibrosis and inflammatory cell infiltration. TAC‑induced cardiac remodeling and dysfunction were effectively ameliorated by administration of anti‑CCR5 but not by IgG control antibody. Mechanistically, increased ERK1/2 and P38 phosphorylation was detected in TAC hearts and Ang II‑stimulated H9c2 cardiomyocytes. Treatment with anti‑CCR5 antibody decreased ERK1/2 and P38 phosphorylation and attenuated Ang II‑induced H9c2 cell hypertrophy. CCR5 inhibition protected against pressure overload‑induced cardiac abnormality. The findings of the present study indicate that ERK1/2 and P38 signaling pathways may be involved in the cardioprotective effects of CCR5 inhibition.

T helper cells in synovial fluid of patients with rheumatoid arthritis primarily have a Th1 and a CXCR3+Th2 phenotype

Background

The majority of CD4⁺ T helper (Th) cells found in the synovial fluid (SF) of patients with rheumatoid arthritis (RA) express CXCR3, a receptor associated with Th1 cells. In blood, subsets of Th2 and Th17 cells also express CXCR3, but it is unknown if these cells are present in RA SF or how cytokines from these subsets affect cytokine/chemokine secretion by fibroblast-like synoviocytes (FLS) from patients with RA.

Methods

We examined the proportions of Th1, Th2, CXCR3⁺Th2, Th17, CXCR3⁺Th17, Th1Th17, peripheral T helper (TPh) and T follicular helper (TFh) cells in paired SF and blood, as well as the phenotype of TPh and TFh cells in RA SF (n = 8), by the use of flow cytometry. We also examined the cytokine/chemokine profile in paired SF and plasma (n = 8) and in culture supernatants of FLS from patients with chronic RA (n = 7) stimulated with Th-associated cytokines, by the use of cytometric bead arrays and ELISA. Cytokine receptor expression in FLS (n = 3) were assessed by the use of RNA sequencing and qPCR.

Results

The proportions of Th1 and CXCR3⁺Th2 cells were higher in SF than in blood (P < 0.05). TPh and PD-1^highTFh in RA SF were primarily of a Th1 and a CXCR3⁺Th2 phenotype. Moreover, the levels of CXCL9, CXCL10, CCL20, CCL2, CXCL8, IL-6 and IL-10 were higher in SF than in plasma (P < 0.05). Lastly, IL-4, IL-13 and IL-17A induced RA FLS to secrete proinflammatory IL-6, CCL2, CXCL1 and CXCL8, while IFNγ mainly induced CXCL10.

Conclusion

These findings indicate that not only Th1 but also CXCR3⁺Th2 cells may have a pathogenic role in RA synovial inflammation.

Innate immunity drives pathogenesis of rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease affecting ∼1% of the general population. This disease is characterized by persistent articular inflammation and joint damage driven by the proliferating synovial tissue fibroblasts as well as neutrophil, monocyte and lymphocyte trafficking into the synovium. The factors leading to RA pathogenesis remain poorly elucidated although genetic and environmental factors have been proposed to be the main contributors to RA. The majority of the early studies focused on the role of lymphocytes and adaptive immune responses in RA. However, in the past two decades, emerging studies showed that the innate immune system plays a critical role in the onset and progression of RA pathogenesis. Various innate immune cells including monocytes, macrophages and dendritic cells are involved in inflammatory responses seen in RA patients as well as in driving the activation of the adaptive immune system, which plays a major role in the later stages of the disease. Here we focus the discussion on the role of different innate immune cells and components in initiation and progression of RA. New therapeutic approaches targeting different inflammatory pathways and innate immune cells will be highlighted here. Recent emergence and the significant roles of innate lymphoid cells and inflammasomes will be also discussed.

Bone marrow mesenchymal stem cells improve bone erosion in collagen-induced arthritis by inhibiting osteoclasia-related factors and differentiating into chondrocytes

Background

Rheumatoid arthritis (RA) is characterized by joint inflammation and damage to the cartilage and bone in collagen-induced arthritis (CIA). Mesenchymal stem cells (MSCs) can improve articular symptoms and reduce bone erosion in CIA rats; however, the underlying mechanism remains unknown. This study aimed to investigate the mechanism underlying MSC-induced improvement of bone destruction in CIA.

Methods

Wistar rats were divided into a normal group, CIA control group, MTX intervention group, and BMSC intervention group, each comprising 8 rats. Serum RANKL, OPG, and CXCL10 levels of all groups were determined via flow cytometry after 42 days of interventions. RANKL, OPG, TRAF6, CXCL10, and CXCR3 were detected on the synovial membrane via immunohistochemistry, and their relative mRNA levels were determined via RT-PCR analysis. BMSCs were labeled with GFP and administered to CIA rats via the tail vein. At different time points, the distribution of implanted GFP-MSCs in synovial tissues was observed using a fluorescence microscope, and the potential of GFP-MSCs to differentiate into chondrocytes was assessed via immunofluorescence analysis.

Results

BMSC transplantation improved joint inflammation and inhibited bone destruction in CIA rats. BMSCs inhibited the expression of serum CXCL10 and CXCL10 and CXCR3 expression at the synovial membrane. Moreover, protein and mRNA expression analyses revealed that BMSCs potentially regulated RANKL/OPG expression levels in the serum and synovial tissue. Upon implantation into CIA rats, GFP-MSCs were traced in the joints. GFP-positive cells were observed in the cartilage tissue from day 11 and until 42 days after transplantation. Anti-type II collagen/GFP double-positive cells were observed in the articular cartilage (especially damaged cartilage) upon immunofluorescence staining of anti-type II collagen.

Conclusions

BMSCs improve bone destruction in CIA by inhibiting the CXCL10/CXCR3 chemotactic axis, regulating the RANKL/OPG ratio, and directly differentiating into chondrocytes.

Synergistic induction of CCL5, CXCL9 and CXCL10 by IFN-γ and NLRs ligands on human fibroblast-like synoviocytes-A potential immunopathological mechanism for joint inflammation in rheumatoid arthritis

Interferon-γ (IFN-γ) is traditionally regarded as a proinflammatory cytokine by virtue of its strong macrophage activating potential and its association with Th1 driven immune responses. NOD1 and NOD2 are cytoplasmic receptors that can initiate the initial immune response by sensing bacterial components or danger signals. In this study, we investigated the immunopathological roles of IFN-γ and NOD1, 2 ligands iE-DAP/MDP on the activation of fibroblast-like synoviocytes (FLS) in RA. FLS constitutively express functional NOD1 and NOD2, and the gene and protein expression of NOD1 and NOD2 could be enhanced by the treatment with IFN-γ. The synergistic effect was observed in the combined treatment of IFN-γ and NOD1 ligand iE-DAP or NOD2 ligand MDP on the release of CCL5, CXCL9 and CXCL10 from FLS, and its effect was in a dose-dependent manner. The co-stimulation which IFN-γ combined with iE-DAP/MDP could abolish the inhibition of CXCL8 level by IFN-γ alone. Further investigations showed that synergistic effects on the production of CCL5, CXCL9 and CXCL10 in FLS stimulated by IFN-γ and iE-DAP/MDP were differentially regulated by intracellular activation of NF-κB, p38MAPK and ERK pathways. In conclusion, our data confirmed the inflammatory effect of IFN-γ and iE-DAP/MDP on human FLS for the first time and therefore provided a new insight into the IFN-γ combined with NOD1 or NOD2 activated immunopathological mechanisms mediated by distinct intracellular signal transduction in joint inflammation of RA.

Activin A Expressed in Rheumatoid Synovial Cells Downregulates TNFα-Induced CXCL10 Expression and Osteoclastogenesis

OBJECTIVE

Activin A is known to be highly expressed in rheumatoid synovium. In the present study, we investigated the effect of inflammatory cytokines on activin A production and its role in rheumatoid inflammation using freshly prepared rheumatoid synovial cells (fresh-RSC).

METHODS

Fresh-RSC from patients with rheumatoid arthritis were obtained and stimulated with multiple cytokines for activin A production. Gene expression levels of activin A and inflammatory cytokines were determined by quantitative PCR (qPCR) analysis. An enzyme-linked immunosorbent assay (ELISA) was used to measure activin A and CXCL10 in culture supernatants. The osteoclasts generated from human peripheral monocytes by RANKL stimulation were identified by tartrate-resistant acid phosphatase staining and bone resorption assay using Osteo plate. The expression levels of NFATc1 and cathepsin K, critical intracellular proteins for osteoclastogenesis, were determined by Western blotting.

RESULTS

Activin A production in fresh-RSC was markedly enhanced by the synergistic effect of TGF-β1 with inflammatory cytokines, including TNFα, IL-1β, and IL-6. Activin A inhibited TNFα-induced CXCL10, an important chemoattractant for pathogen-activated T cells and monocytes of osteoclast precursors, but it did not affect the expression of inflammatory cytokines and chemokines. In addition, activin A directly inhibited the expression of NFATc1 and cathepsin K, as well as osteoclast formation in human samples.

CONCLUSION

Our data indicated that TGF-β1 is involved in the expression of activin A at inflamed joints. Activin A mainly exerts an anti-inflammatory action, which prevents joint damage via the regulation of CXCL10 and osteoclastogenesis.

Epidermal Damage Induces Th1 Polarization and Defines the Site of Inflammation in Murine Epidermolysis Bullosa Acquisita

Epidermolysis bullosa acquisita is an autoimmune skin disease characterized by subepidermal blisters. The pathogenesis is mediated by deposits of autoantibodies directed against type VII collagen in the skin, but the sequence of events regulating the localization of skin blisters is not fully understood. In this study, using the immunization-induced mouse model of epidermolysis bullosa acquisita, we demonstrate that epidermal disruption induces not only an infiltration of CD4⁺ T cells but also a T helper type 1 phenotype as it has been described for delayed-type hypersensitivity reactions. This T helper type 1 reaction was not found when different antigens were applied. Deep T-cell receptor β profiling revealed shifts in the V/J gene usage only in epidermolysis bullosa acquisita, suggesting an infiltration of autoantigen-specific T cells. To target these autoantigen-specific T cells, we established an approach with which skin inflammation could be prevented without impairing the functionality of autoantibodies. We conclude that T-cell involvement in skin blistering diseases such as epidermolysis bullosa acquisita relates not only to T-cell help for B cells that produce pathogenic autoantibodies but also to autoreactive T helper type 1 effector cells that migrate into injured skin sites, exacerbate inflammation through production of inflammatory cytokines such as IFNγ, and prevent wound healing.

Maraviroc attenuates the pathogenesis of experimental autoimmune encephalitis

It has been shown that the blockade of chemokine receptor type 5 can dampen inflammatory reaction within the central nervous system (CNS). In the present study, we utilized maraviroc, a potent antagonist o CCR5, to examine whether this drug can mitigate neuroinflammation in the spinal cord of mice induced by experimental autoimmune encephalitis (EAE), considered a murine model of multiple sclerosis (MS). For this aim, mice were immunized with myelin oligodendrocyte glycoprotein 35-55 (MOG35-55), followed by pertussis toxin to induce paralysis in EAE mice. The animals intraperitoneally received various doses of maraviroc (5, 25, and 50 mg/kg body weight) when the early clinical signs of EAE appeared. The results demonstrated that the administration of maraviroc led to a marked decrease in the clinical score and improvement in behavioral motor functions. Moreover, our finding indicated that the administration of maraviroc significantly attenuates the infiltration of inflammatory cells to the spinal cord, microgliosis, astrogliosis, pro-inflammatory cytokines, and cell death in EAE mice. The flow cytometry data indicated that a decreased number of CD4+ and CD8+ T cells in the peripheral blood of mice with EAE without affecting the number of T regulatory cells (CD4 + CD25+ forkhead box protein 3+). Finally, it seems that maraviroc is well-tolerated, and targeting CCR5 could open up a new horizon in the treatment of MS.

C-C chemokine receptor type 5 links COVID-19, rheumatoid arthritis, and Hydroxychloroquine: in silico analysis

Patients with rheumatoid arthritis (RA) represent one of the fragile patient groups that might be susceptible to the critical form of the coronavirus disease - 19 (COVID-19). On the other side, RA patients have been found not to have an increased risk of COVID-19 infection. Moreover, some of the Disease-Modifying Anti-Rheumatic Drugs (DMARDS) commonly used to treat rheumatic diseases like Hydroxychloroquine (HCQ) were proposed as a potential therapy for COVID-19 with a lack of full understanding of their molecular mechanisms. This highlights the need for the discovery of common pathways that may link both diseases at the molecular side. In this research, we used the in silico approach to investigate the transcriptomic profile of RA synovium to identify shared molecular pathways with that of severe acute respiratory syndrome-corona virus-2 (SARS-COV-2) infected lung tissue. Our results showed upregulation of chemotactic factors, including CCL4, CCL8, and CCL11, that all shared CCR5 as their receptor, as a common derangement observed in both diseases; RA and COVID-19. Moreover, our results also highlighted a possible mechanism through which HCQ, which can be used as a monotherapy in mild RA or as one of the triple-DMARDs therapy (tDMARDs; methotrexate, sulphasalazine, and HCQ), might interfere with the COVID-19 infection. This might be achieved through the ability of HCQ to upregulate specific immune cell populations like activated natural killer (NK) cells, which were found to be significantly reduced in COVID-19 infection. In addition to its ability to block CCR5 rich immune cell recruitment that also was upregulated in the SARS-COV-2 infected lungs. This might explain some of the reports that showed beneficial effects.

Meta-Analysis of in vitro-Differentiated Macrophages Identifies Transcriptomic Signatures That Classify Disease Macrophages in vivo

Macrophages are heterogeneous leukocytes regulated in a tissue- and disease-specific context. While in vitro macrophage models have been used to study diseases empirically, a systematic analysis of the transcriptome thereof is lacking. Here, we acquired gene expression data from eight commonly-used in vitro macrophage models to perform a meta-analysis. Specifically, we obtained gene expression data from unstimulated macrophages (M0) and macrophages stimulated with lipopolysaccharides (LPS) for 2–4 h (M-LPS_early), LPS for 24 h (M-LPS_late), LPS and interferon-γ (M-LPS+IFNγ), IFNγ (M-IFNγ), interleukin-4 (M-IL4), interleukin-10 (M-IL10), and dexamethasone (M-dex). Our meta-analysis identified consistently differentially expressed genes that have been implicated in inflammatory and metabolic processes. In addition, we built macIDR, a robust classifier capable of distinguishing macrophage activation states with high accuracy (>0.95). We classified in vivo macrophages with macIDR to define their tissue- and disease-specific characteristics. We demonstrate that alveolar macrophages display high resemblance to IL10 activation, but show a drop in IFNγ signature in chronic obstructive pulmonary disease patients. Adipose tissue-derived macrophages were classified as unstimulated macrophages, but acquired LPS-activation features in diabetic-obese patients. Rheumatoid arthritis synovial macrophages exhibit characteristics of IL10- or IFNγ-stimulation. Altogether, we defined consensus transcriptional profiles for the eight in vitro macrophage activation states, built a classification model, and demonstrated the utility of the latter for in vivo macrophages.

Glucocorticoids-All-Rounders Tackling the Versatile Players of the Immune System

Glucocorticoids regulate fundamental processes of the human body and control cellular functions such as cell metabolism, growth, differentiation, and apoptosis. Moreover, endogenous glucocorticoids link the endocrine and immune system and ensure the correct function of inflammatory events during tissue repair, regeneration, and pathogen elimination via genomic and rapid non-genomic pathways. Due to their strong immunosuppressive, anti-inflammatory and anti-allergic effects on immune cells, tissues and organs, glucocorticoids significantly improve the quality of life of many patients suffering from diseases caused by a dysregulated immune system. Despite the multitude and seriousness of glucocorticoid-related adverse events including diabetes mellitus, osteoporosis and infections, these agents remain indispensable, representing the most powerful, and cost-effective drugs in the treatment of a wide range of rheumatic diseases. These include rheumatoid arthritis, vasculitis, and connective tissue diseases, as well as many other pathological conditions of the immune system. Depending on the therapeutically affected cell type, glucocorticoid actions strongly vary among different diseases. While immune responses always represent complex reactions involving different cells and cellular processes, specific immune cell populations with key responsibilities driving the pathological mechanisms can be identified for certain autoimmune diseases. In this review, we will focus on the mechanisms of action of glucocorticoids on various leukocyte populations, exemplarily portraying different autoimmune diseases as heterogeneous targets of glucocorticoid actions: (i) Abnormalities in the innate immune response play a crucial role in the initiation and perpetuation of giant cell arteritis (GCA). (ii) Specific types of CD4+ T helper (Th) lymphocytes, namely Th1 and Th17 cells, represent important players in the establishment and course of rheumatoid arthritis (RA), whereas (iii) B cells have emerged as central players in systemic lupus erythematosus (SLE). (iv) Allergic reactions are mainly triggered by several different cytokines released by activated Th2 lymphocytes. Using these examples, we aim to illustrate the versatile modulating effects of glucocorticoids on the immune system. In contrast, in the treatment of lymphoproliferative disorders the pro-apoptotic action of glucocorticoids prevails, but their mechanisms differ depending on the type of cancer. Therefore, we will also give a brief insight into the current knowledge of the mode of glucocorticoid action in oncological treatment focusing on leukemia.

Rheumatoid arthritis-like active synovitis with T-cell activation in a case of idiopathic multicentric Castleman disease: A case report

RATIONALE

Idiopathic multicentric Castleman disease (iMCD) is a systemic disease with multiple regions of lymphadenopathy and systemic symptoms and associated with rheumatoid arthritis (RA) and collagen diseases. However, few reported have described the coexistence of iMCD and RA and the mechanisms by which iMCD induces arthritis remain elusive. We experienced a rare case of iMCD, wherein the patient exhibited symptoms of polyarthritis with high-grade fever.

PATIENT CONCERNS

A 34-year-old woman was admitted to our hospital for further evaluation of a high fever with polyarthritis. The levels of both rheumatoid factor and anticitrullinated protein antibody were negative. F-fluorodeoxyglucose/positron emission tomography-computed tomography showed lymphadenopathy with increased fluoro-2-deoxy-D-glucose uptake. Magnetic resonance imaging and musculoskeletal ultrasonography revealed active synovitis in the hands which was consistent with RA.

DIAGNOSES

We diagnosed iMCD based on human herpesvirus 8 negativity, HIV negativity, systemic lymphadenopathy, and pathologic findings of the lymph nodes. The patient did not satisfy the 2010 American College of Rheumatology and European League Against Rheumatism classification criteria for RA. Cytokine assay showed elevated serum levels of interleukin-17 and CXCL10, comparable to those in patients with RA.

INTERVENTIONS

We administered 15 mg/d of predonisolone.

OUTCOMES

After this treatment, the patient's symptoms showed improvement. As of this writing, we tapered the prednisolone to 7.5 mg/d, and the patient's remission has been maintained for >4 months.

LESSONS

The present case suggests that RA-like active synovitis may coexist in iMCD, resulting from aberrant T-cell activation and histologic examination using lymph node biopsy may help enable early diagnosis of iMCD.

FOXO3 is involved in the tumor necrosis factor-driven inflammatory response in fibroblast-like synoviocytes

Fibroblast-like synoviocytes (FLS) are major contributors to joint inflammation in rheumatoid arthritis (RA). Forkhead box O 3 (FOXO3) perturbations in immune cells are increasingly linked to RA pathogenesis. Here, we show that FOXO3 is distinctly inactivated/phosphorylated in the FLS of rheumatoid synovitis. In vitro, stimulation of FLS with tumor necrosis factor-alpha α (TNFα) induced a rapid and sustained inactivation of FOXO3. mRNA profiling revealed that the inactivation of FOXO3 is important for the sustained pro-inflammatory interferon response to TNFα (CXCL9, CXCL10, CXCL11, and TNFSF18). Mechanistically, our studies demonstrate that the inactivation of FOXO3 results from TNF-induced downregulation of phosphoinositide-3-kinase-interacting protein 1 (PIK3IP1). Thus, we identified FOXO3 and its modulator PIK3IP1 as a critical regulatory circuit for the inflammatory response of the resident mesenchymal cells to TNFα and contribute insight into how the synovial tissue brings about chronic inflammation that is driven by TNFα.

The many facets of macrophages in rheumatoid arthritis

Macrophages are central to the pathophysiology of rheumatoid arthritis (RA). They constitute the main source of pro-inflammatory cytokines and chemokines such as TNF and IL-1β, they activate a wide range of immune and non-immune cells, and they secrete diverse tissue degrading enzymes driving chronic pro-inflammatory, tissue destructive and pain responses in RA. However, they can also produce anti-inflammatory cytokines such as IL-10, secrete inhibitors of tissue degrading enzymes and promote immunoregulatory and protective responses, suggesting the existence of macrophages with distinct and diverse functional activities. Although the underlying basis of this phenomenon has remained obscure for years, emerging evidence has now provided insight into the mechanisms and molecular processes involved. Here, we review current knowledge on the biology of macrophages in RA, and highlight recent literature on the heterogeneity, origins and ontogeny of macrophages as part of the mononuclear phagocyte system. We also discuss their plasticity in the context of the M1/M2 paradigm, and the emerging theme of metabolic rewiring as a major mechanism for programming macrophage functions and pro-inflammatory activities. This sheds light into the many facets of macrophages in RA, their molecular regulation and their translational potential for developing novel protective and therapeutic strategies in the clinic.

Effector Functions of CD4+ T Cells at the Site of Local Autoimmune Inflammation-Lessons From Rheumatoid Arthritis

Infiltration of memory CD4+ T cells in synovial joints of Rheumatoid Arthritis (RA) patients has been reported since decades. Moreover, several genome wide association studies (GWAS) pinpointing a key genetic association between the HLA-DR locus and RA have led to the generally agreed hypothesis that CD4+ T cells are directly implicated in the disease. Still, RA is a heterogeneous disease and much effort has been made to understand its different facets. T cell differentiation is driven by mechanisms including antigen stimulation, co-stimulatory signals and cytokine milieu, all of which are abundant in the rheumatic joint, implying that any T cells migrating into the joint may be further affected locally. In parallel to the characterization and classification of T-cell subsets, the contribution of different effector T cells to RA has been investigated in numerous studies though sometimes with contradictory results. In particular, the frequency of Th1 and Th17 cells has been assessed in the synovial joints with various results that could, at least partly, be explained by the stage of the disease. For regulatory T cells, it is largely accepted that they accumulate in RA synovial fluid and that the equilibrium between regulatory T cells and effector cells is a key factor in controlling inflammation processes involved in RA. Recent phenotypic studies describe the possible implication of a novel subset of peripheral T helper cells (Tph) important for T-B cell cross talk and plasma cell differentiation in the RA joint of ACPA+ (autoantibodies against citrullinated proteins) RA patients. Finally, cytotoxic CD4+ T cells, historically described as increased in the peripheral blood of RA patients have attracted new attention in the last years. In view of the recently identified peripheral T-cell subsets, we will integrate immunological data as well as information on genetic variants and therapeutic strategy outcomes into our current understanding of the width of effector T cells. We will also integrate tissue-resident memory T cell aspects, and discuss similarities and differences with inflammatory conditions in skin (psoriasis) and mucosal organs (Crohn's disease).

High percentages and activity of synovial fluid NK cells present in patients with advanced stage active Rheumatoid Arthritis

Rheumatoid Arthritis (RA) causes chronic inflammation of joints. The cytokines TNFα and IFNγ are central players in RA, however their source has not been fully elucidated. Natural Killer (NK) cells are best known for their role in elimination of viral-infected and transformed cells, and they secrete pro-inflammatory cytokines. NK cells are present in the synovial fluids (SFs) of RA patients and are considered to be important in bone destruction. However, the phenotype and function of NK cells in the SFs of patients with erosive deformative RA (DRA) versus non-deformative RA (NDRA) is poorly characterized. Here we characterize the NK cell populations present in the blood and SFs of DRA and NDRA patients. We demonstrate that a distinct population of activated synovial fluid NK (sfNK) cells constitutes a large proportion of immune cells found in the SFs of DRA patients. We discovered that although sfNK cells in both DRA and NDRA patients have similar phenotypes, they function differently. The DRA sfNK secrete more TNFα and IFNγ upon exposure to IL-2 and IL-15. Consequently, we suggest that sfNK cells may be a marker for more severely destructive RA disease.

Platelet-derived microparticles generated in vitro resemble circulating vesicles of patients with rheumatoid arthritis and activate monocytes

Patients with rheumatoid arthritis (RA) have increased amount of platelet-derived microparticles (PMPs) positive for citrullinated peptides (CPs) that form immune complexes (PMPs-ICs). Monocytes are important inflammatory mediators that play a role in the clearance of PMPs-ICs. We aimed to generate PMPs-ICs in vitro and determine its effect on monocytes from patients with RA and healthy individuals (HI). PMPs from patients showed platelet markers, mitochondria content, and phosphatidylserine exposure similar to PMPs from HI. However, patients had a higher frequency of IgG+ and CPs+ vesicles than HI. PMPs-ICs generated in vitro were similar to the circulating vesicles of patients with respect to IgG- and CPs-positivity. PMPs-ICs induced pro-inflammatory cytokines and CX3CR1 expression in monocytes from HI, and IL-10 and CD36 upregulation in monocytes from patients. These results suggest that PMPs-ICs induce activation of monocytes, with a pro-inflammatory response in HI and a more tolerant response in cells of patients with RA.

T Follicular Helper-Like Cells in Inflamed Non-Lymphoid Tissues

T and B cell cooperation normally takes place in secondary lymphoid organs (SLO). However, both cell types are also frequently found in inflamed non-lymphoid tissues. Under certain conditions, these infiltrates develop into ectopic lymphoid structures, also known as tertiary lymphoid tissues, which structurally and functionally fully resemble germinal centers (GCs) in SLO. However, tertiary lymphoid tissue is uncommon in most human autoimmune conditions; instead, relatively unstructured T and B cell infiltrates are found. Recent studies have demonstrated that active T and B cell cooperation can also take place in such unstructured aggregates. The infiltrating cells contain a population of T follicular helper (Tfh)-like cells (also designated "peripheral T helper cells") lacking prototypic Tfh markers like CXCR5 and Bcl-6 but nevertheless expressing high levels of molecules important for B cell help like IL-21 and CD40L. Moreover, Tfh-like cells isolated from inflamed tissues can drive the differentiation of B cells into antibody-secreting cells in vitro. These findings are not restricted to experimental animal models but have been reproduced in rheumatoid arthritis and breast cancer patients. At this point, it is unclear whether T and B cell cooperation outside the ordered structure of the GC fully mirrors the reactions in SLO. However, Tfh-like cells in inflamed tissues are certainly important for the local differentiation of B cells into antibody-secreting cells, and should be considered as an important target for the treatment of autoimmune diseases.

Upregulation of chemokine CXCL10 enhances chronic pulmonary inflammation in tree shrew collagen-induced arthritis

Chronic pulmonary inflammation (CPI) gives rise to serious lung injuries in rheumatoid arthritis (RA) patients. However, the molecular mechanism underlying the pathogenesis of RA-associated CPI remains little understood. Here we established a novel tree shrew-based collagen-induced arthritis (TsCIA) model to study RA-associated CPI. Our results showed that typical CPI but not fibrosis developed pathologically in the TsCIA model. Furthermore, abnormal up-regulation of pulmonary chemokine CXCL10 was directly associated with lung damage. Specific blockage of CXCR3 (a CXCL10 receptor) significantly decreased the severity of CPI by decreasing the recruitment of inflammatory cells. Therefore, CXCL10 is proposed as a key player responsible for the development of TsCIA-associated CPI. Our findings also suggest that CXCR3 could be developed as a potential diagnosis biomarker for RA-associated CPI.

CXCL10-induced IL-9 promotes liver fibrosis via Raf/MEK/ERK signaling pathway

Liver fibrosis is a typical complication of chronic liver diseases resulting in cirrhosis that remains a major public health problem. The aim of the present study was to identify the role of interleukin-9 (IL-9), an important regulator of inflammation and autoimmune diseases, in hepatic fibrosis progression. It was found that the expression of IL-9 was significantly increased in liver tissues of liver cirrhosis patients compared with that in healthy controls. Moreover, CXCL10, not CXCL9 or CXCL11, induced IL-9 expression in the liver tissue. Overexpression of IL-9 enhanced the severity of liver fibrosis in the carbon tetrachloride (CCl₄)-induced liver fibrosis model. Western Blotting analysis revealed that this pro-fibrosis bioactivity of IL-9 was attributed to its selective activation of Raf/MEK/ERK signaling. Finally, administration of neutralizing anti-IL-9 antibody ameliorated liver fibrosis and attenuated the activation of hepatic stellate cells in mice. All these findings indicate that IL-9 plays a deleterious role in the development and progression of liver fibrosis, and IL-9 based immunotherapy may prove to be a promising strategy for the treatment of liver fibrosis.

Chronic inflammatory lesions of the placenta are associated with an up-regulation of amniotic fluid CXCR3: A marker of allograft rejection

OBJECTIVE

The objective of this study is to determine whether the amniotic fluid (AF) concentration of soluble CXCR3 and its ligands CXCL9 and CXCL10 changes in patients whose placentas show evidence of chronic chorioamnionitis or other placental lesions consistent with maternal anti-fetal rejection.

METHODS

This retrospective case-control study included 425 women with (1) preterm delivery (n=92); (2) term in labor (n=68); and (3) term not in labor (n=265). Amniotic fluid CXCR3, CXCL9 and CXCL10 concentrations were determined by ELISA.

RESULTS

(1) Amniotic fluid concentrations of CXCR3 and its ligands CXCL9 and CXCL10 are higher in patients with preterm labor and maternal anti-fetal rejection lesions than in those without these lesions [CXCR3: preterm labor and delivery with maternal anti-fetal rejection placental lesions (median, 17.24 ng/mL; IQR, 6.79-26.68) vs. preterm labor and delivery without these placental lesions (median 8.79 ng/mL; IQR, 4.98-14.7; P=0.028)]; (2) patients with preterm labor and chronic chorioamnionitis had higher AF concentrations of CXCL9 and CXCL10, but not CXCR3, than those without this lesion [CXCR3: preterm labor with chronic chorioamnionitis (median, 17.02 ng/mL; IQR, 5.57-26.68) vs. preterm labor without chronic chorioamnionitis (median, 10.37 ng/mL; IQR 5.01-17.81; P=0.283)]; (3) patients with preterm labor had a significantly higher AF concentration of CXCR3 than those in labor at term regardless of the presence or absence of placental lesions.

CONCLUSION

Our findings support a role for maternal anti-fetal rejection in a subset of patients with preterm labor.

The Expanding Therapeutic Perspective of CCR5 Blockade

CCR5 and its interaction with chemokine ligands have been crucial for understanding and tackling HIV-1 entry into target cells. However, over time, CCR5 has witnessed an impressive transition from being considered rather unimportant in physiology and pathology to becoming central in a growing number of pathophysiological conditions. It now turns out that the massive efforts devoted to combat HIV-1 entry by interfering with CCR5, and the subsequent production of chemokine ligand variants, small chemical compounds, and other molecular entities and strategies, may set the therapeutic standards for a wealth of different pathologies. Expressed on various cell types, CCR5 plays a vital role in the inflammatory response by directing cells to sites of inflammation. Aside HIV-1, CCR5 has been implicated in other infectious diseases and non-infectious diseases such as cancer, atherosclerosis, and inflammatory bowel disease. Individuals carrying the CCR5Δ32 mutation live a normal life and are warranted a natural barrier to HIV-1 infection. Therefore, CCR5 antagonism and gene-edited knockout of the receptor gained growing interest for the therapeutic role that CCR5 blockade may play in the attenuation of the severity or progression of numerous diseases.

CCR5 knockout suppresses experimental autoimmune encephalomyelitis in C57BL/6 mice

Multiple sclerosis (MS) is an inflammatory disease in which myelin in the spinal cord is damaged. C-C chemokine receptor type 5 (CCR5) is implicated in immune cell migration and cytokine release in central nervous system (CNS). We investigated whether CCR5 plays a role in MS progression using a murine model, experimental autoimmune encephalomyelitis (EAE), in CCR5 deficient (CCR5-/-) mice. CCR5-/- and CCR5+/+ (wild-type) mice were immunized with myelin oligodendrocyte glycoprotein 35-55 (MOG35-55) followed by pertussis toxin, after which EAE paralysis was scored for 28 days. We found that clinical scoring and EAE neuropathology were lower in CCR5-/- mice than CCR5+/+ mice. Immune cells (CD3+, CD4+, CD8+, B cell, NK cell and macrophages) infiltration and astrocytes/microglial activation were attenuated in CCR5-/- mice. Moreover, levels of IL-1β, TNF-α, IFN-γ and MCP-1 cytokine levels were decreased in CCR5-/- mice spinal cord. Myelin basic protein (MBP) and CNPase were increased while NG2 and O4 were decreased in CCR5-/- mice, indicating that demyelination was suppressed by CCR5 gene deletion. These findings suggest that CCR5 is likely participating in demyelination in the spinal cord the MS development, and that it could serve as an effective therapeutic target for the treatment of MS.

RANTES/CCL5 Induces Collagen Degradation by Activating MMP-1 and MMP-13 Expression in Human Rheumatoid Arthritis Synovial Fibroblasts

Regulated on activation, normal T expressed, and secreted (RANTES)/CC ligand 5 (CCL5) participates in rheumatoid arthritis (RA) pathogenesis by facilitating leukocyte infiltration, however, its other pathological functions are not fully defined in RA. In the present study, we evaluated the effect of RANTES/CCL5 on tissue degrading enzymes matrix metalloproteinase-1 (MMP-1) and MMP-13 expression and its contribution to the progressive joint damage by RA synovial fibroblasts (RASFs). Our results showed that RANTES/CCL5 dose dependently induced MMP-1 and MMP-13 expression in monolayers and three-dimensional (3D) micromass of human RASFs, which correlated with an increase in collagenase activity. This activation by RANTES/CCL5 was observed in RASF, but not in osteoarthritis SFs (OASFs). Evaluation of the signaling events showed that RANTES/CCL5 selectively activated PKCδ, JNK, and ERK proteins to induce MMP expression in human RASFs. Pretreatment with a functional antagonist (Met-RANTES) or heparinase III [an enzyme that selectively digests heparan sulfate proteoglycans (HSPGs)] completely abrogated RANTES/CCL5-induced MMP-1 and MMP-13 expression. Interestingly, the inhibition of RANTES/CCL5 using small-interfering RNA approach reduced the ability of interleukin-1β (IL-1β) to induce MMP-1 and MMP-13 expression, asserting its mediatory role in tissue remodeling. In the inhibitor study, only the selective inhibition of HSPGs or PKCδ, ERK, and JNK markedly inhibited RANTES/CCL5-induced MMP-1 and MMP-13 production. Circular dichroism spectroscopy results demonstrated the degradation of collagen triple-helical structure upon exposure to the conditioned media from RANTES/CCL5 stimulated RASFs, which was reverted by a broad-spectrum MMP inhibitor (GM6001). These findings suggest that RANTES/CCL5 not only upregulates MMP-1 and MMP-13 expression by partly utilizing HSPGs and/or PKCδ-JNK/ERK pathways but also mediates IL-1β-induced MMP-1 and MMP-13 expression.

Differential regulation by IFN‑γ on TNF‑α‑induced chemokine expression in synovial fibroblasts from temporomandibular joint

Tumor necrosis factor (TNF)‑α and interferon (IFN)‑γ, are inflammatory cytokines in the synovial fluid of patients with temporomandibular joint disorder (TMD). However, it remains unknown whether they participate in the regulation of various chemokine expression levels associated with TMD. The effects of TNF‑α and IFN‑γ on the expression of several different inflammatory chemokines, including interleukin (IL)‑8, C‑X‑C motif chemokine ligand (CXCL)1, C‑C motif chemokine ligand (CCL)20, CXCL9, CXCL10, and CXCL11 in synovial fibroblasts obtained from the temporomandibular joint (TMJ) were examined. The results demonstrated that TNF‑α increased the mRNA levels of all examined chemokines in synovial fibroblasts obtained from the TMJ. IFN‑γ treatment alone increased the mRNA expression levels of CXCR3 chemokines, including CXCL10, while they were significantly enhanced when administered in combination with TNF‑α compared with either treatment alone. However, the combination of IFN‑γ and TNF‑α resulted in lower mRNA expression levels of IL‑8 and CXCL1 as compared with those induced by TNF‑α alone. The nuclear factor‑κB inhibitor, Bay 11‑7082, decreased the TNF‑α‑mediated expression of IL‑8 and CXCL10 in the absence, and presence of IFN‑γ. In addition, the JAK2 inhibitor, AG490, decreased CXCL10 expression when administered with TNF‑α and IFN‑γ. Finally, the decrease in TNF‑α‑induced IL‑8 caused by IFN‑γ was recovered by AG490. The results of the present study suggest that TNF‑α and IFN‑γ function in a cooperative manner to regulate inflammatory chemokine expression in synovial fibroblasts, which may contribute to the pathological condition of the TMJ.

Chemotaxis of Vδ2 T cells to the joints contributes to the pathogenesis of rheumatoid arthritis

OBJECTIVES

To explore the role of Vδ2 T cells in the pathogenesis of rheumatoid arthritis (RA).

METHODS

Sixty-eight patients with RA, 21 patients with osteoarthritis and 21 healthy controls were enrolled in the study. All patients with RA fulfilled the 2010 American College of Rheumatology/European League Against Rheumatism criteria for RA. Peripheral Vδ2T population, chemokine receptor expression and proinflammatory cytokine secretion were quantified by flow cytometry. The infiltration of Vδ2 T cells within the synovium was examined by immunohistochemistry and flow cytometry. The effect of tumour necrosis factor (TNF)-α and interleukin (IL)-6 on Vδ2 T migration was determined by flow cytometry and transwell migration assay.

RESULTS

Peripheral Vδ2T cells, but not Vδ1 T cells, were significantly lower in patients with RA, which was negatively correlated with disease activity gauged by Disease Activity Score in 28 joints. Vδ2 T cells from RA accumulated in the synovium and produced high levels of proinflammatory cytokines including interferon-γ and IL-17. Phenotypically, Vδ2 T cells from RA showed elevated chemotaxis potential and expressed high levels of chemokine receptors CCR5 and CXCR3, which was driven by increased serum TNF-α through nuclear factor kappa B signalling. In vivo, TNF-α neutralising therapy dramatically downregulated CCR5 and CXCR3 on Vδ2 T cells and repopulated the peripheral Vδ2 T cells in patients with RA.

CONCLUSIONS

High levels of TNF-α promoted CCR5 and CXCR3 expression in Vδ2 T cells from RA, which potentially infiltrated into the synovium and played crucial roles in the pathogenesis of RA. Targeting Vδ2 T cells might be a potential approach for RA.

CXCR3 plays a critical role for host protection against Salmonellosis

CXCR3 and its ligands are heavily associated with inflammation and have been implicated in numerous inflammatory diseases. CXCR3 plays an important role in recruiting pro-inflammatory cells, specifically neutrophils, in a model of sterile colitis whereby CXCR3^−/− mice showed an attenuated course of colitis with markedly reduced host-tissue damage in the inflamed caecum. The role of CXCR3 during infectious colitis, however, is unclear and therefore in this study, we investigated the role of CXCR3 in the regulation of the immune response during acute and chronic gastrointestinal infection, using a murine model of Salmonella enterica serovar Enteritidis. During acute infection with Salmonella, we observed significantly increased Salmonella loading in the caecum and dissemination to the spleen and liver in CXCR3^−/− mice, but not in Wt counterparts. During chronic infection, increased pathological features of inflammation were noted in the spleen and liver, with significantly increased levels of apoptosis in the liver of CXCR3^−/− mice, when compared to Wt counterparts. In addition, compromised intestinal IgA levels, CD4⁺ helper T cells and neutrophil recruitment were observed in CXCR3^−/− challenged with Salmonella, when compared to Wt counterparts. Our data suggests that CXCR3 is a key molecule in host intestinal immunity against Salmonellosis via regulating neutrophils chemotaxis.