Myositis Autoantibody Profiles and Clinical Significance in Patients with Inflammatory Myopathies in Southwest China.

BACKGROUND: The purpose of this study is to analyze the distribution of myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs) in patients with idiopathic inflammatory myopathies (IIMs) in southwest China and to explore the relevance between each subtype, each clinical feature, and to explore the relevance between the laboratory indexes. METHODS: For this study, 200 patients with IIMs were tested for myositis autoantibodies. Clinical manifestations and laboratory metrics were collected and the correlations between autoantibodies and clinical phenotypes were analyzed. RESULTS: MSAs were found in 73.5% of the patients. The most frequently MSAs were anti-MDA5 (26.8%), followed by anti-ARS (18.5%). Anti-Ro52 was the most prevalent in MAAs (46.2%). Interstitial lung disease (ILD) and arthralgia were more frequent in anti-MDA5 and anti-Jo-1 positive groups (each p < 0.05). Anti-TIF1-γ and anti-NXP2 were associated with dysphagia (each p < 0.05). Different antibody subtypes were associated with laboratory indicators of response to muscle damage and immune status. Logistic regression showed that anti-MDA5 and anti-Jo-1 were independent risk factors for ILD (OR = 4.542, p = 0.004; OR = 4.290, p = 0.018, respectively) and arthralgia (OR = 7.856, p = 0.000; OR = 5.731, p = 0.004, respectively), whereas anti-TIF1-γ and anti-NXP2 were independent risk factors for dysphagia (OR = 4.521, p = 0.009; OR = 6.889, p = 0.017, respectively). CONCLUSIONS: Different antibody subtypes were associated with specific clinical features. Anti-MDA5 and anti-Jo-1 were independent risk factors for ILD and arthralgia. Anti-TIF1-γ and anti-NXP2 were independent risk factors for dysphagia.

Tocilizumab in the treatment of hyperferritinemic syndrome and capillary leak syndrome secondary to rheumatoid arthritis: Case report and literature review.

INTRODUCTION: Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease, which is mainly characterized by joint swelling, pressure pain and joint destruction. Some patients may suffer from a variety of serious complications, which require prompt diagnosis and treatment. Otherwise, the patient condition may deteriorate rapidly, leading to premature death. OBJECTIVE: We reported a case of RA combined with hyperferritinemic syndrome and capillary leak syndrome (CLS) that was successfully treated with tocilizumab (TCZ), with the aim of improving diagnostic ideas for clinicians and consequently improving the diagnosis and treatment of the hyperferritinemic syndrome and CLS. CASE SUMMARY: A 55-year-old female patient was admitted to the Department of Infectious Diseases of our hospital due to "recurrent fever for more than 1 month and aggravation for 3 days." The patient was diagnosed with fever of unknown origin (lung infection?) and received anti-infective therapy with large encirclement of anti-bacterial, antifungal and empirical anti-tuberculosis successively during hospitalization in the Department of Infectious Diseases. Yet her condition continues to progress. The patient was eventually diagnosed with RA combined with hyperferritinemic syndrome and CLS. Then she received glucocorticoids (GC) (160 mg qd) combined with intravenous immunoglobulin (IVIG, 20 g/d, for 3 days). We considered that the patient also had an overwhelming proinflammatory cytokine storm, so she received a strong anti-inflammatory treatment with TCZ (400 mg qm). The patient symptoms and follow-up chest CT showed significant improvement following treatment. CONCLUSION: TCZ has good efficacy in the treatment of RA combined with hyperferritinemic syndrome and CLS and is expected to be a promising treatment.

Tree shrews as a new animal model for systemic sclerosis research.

Objective: Systemic sclerosis (SSc) is a chronic systemic disease characterized by immune dysregulation and fibrosis for which there is no effective treatment. Animal models are crucial for advancing SSc research. Tree shrews are genetically, anatomically, and immunologically closer to humans than rodents. Thus, the tree shrew model provides a unique opportunity for translational research in SSc. Methods: In this study, a SSc tree shrew model was constructed by subcutaneous injection of different doses of bleomycin (BLM) for 21 days. We assessed the degree of inflammation and fibrosis in the skin and internal organs, and antibodies in serum. Furthermore, RNA sequencing and a series of bioinformatics analyses were performed to analyze the transcriptome changes, hub genes and immune infiltration in the skin tissues of BLM induced SSc tree shrew models. Multiple sequence alignment was utilized to analyze the conservation of selected target genes across multiple species. Results: Subcutaneous injection of BLM successfully induced a SSc model in tree shrew. This model exhibited inflammation and fibrosis in skin and lung, and some developed esophageal fibrosis and secrum autoantibodies including antinuclear antibodies and anti-scleroderma-70 antibody. Using RNA sequencing, we compiled skin transcriptome profiles in SSc tree shrew models. 90 differentially expressed genes (DEGs) were identified, which were mainly enriched in the PPAR signaling pathway, tyrosine metabolic pathway, p53 signaling pathway, ECM receptor interaction and glutathione metabolism, all of which are closely associated with SSc. Immune infiltration analysis identified 20 different types of immune cells infiltrating the skin of the BLM-induced SSc tree shrew models and correlations between those immune cells. By constructing a protein-protein interaction (PPI) network, we identified 10 hub genes that were significantly highly expressed in the skin of the SSc models compared to controls. Furthermore, these genes were confirmed to be highly conserved in tree shrews, humans and mice. Conclusion: This study for the first time comfirmed that tree shrew model of SSc can be used as a novel and promising experimental animal model to study the pathogenesis and translational research in SSc.

Development and validation of a new diagnostic prediction model of ENHO and NOX4 for early diagnosis of systemic sclerosis.

Objective: Systemic sclerosis (SSc) is a chronic autoimmune disease characterized by fibrosis. The challenge of early diagnosis, along with the lack of effective treatments for fibrosis, contribute to poor therapeutic outcomes and high mortality of SSc. Therefore, there is an urgent need to identify suitable biomarkers for early diagnosis of SSc. Methods: Three skin gene expression datasets of SSc patients and healthy controls were downloaded from Gene Expression Omnibus (GEO) database (GSE130955, GSE58095, and GSE181549). GSE130955 (48 early diffuse cutaneous SSc and 33 controls) were utilized to screen differentially expressed genes (DEGs) between SSc and normal skin samples. Least absolute shrinkage and selection operator (LASSO) regression and support vector machine recursive feature elimination (SVM-RFE) were performed to identify diagnostic genes and construct a diagnostic prediction model. The results were further validated in GSE58095 (61 SSc and 36 controls) and GSE181549 (113 SSc and 44 controls) datasets. Receiver operating characteristic (ROC) curves were applied for assessing the level of diagnostic ability. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to verify the diagnostic genes in skin tissues of out cohort (10 SSc and 5 controls). Immune infiltration analysis were performed using CIBERSORT algorithm. Results: A total of 200 DEGs were identified between SSc and normal skin samples. Functional enrichment analysis revealed that these DEGs may be involved in the pathogenesis of SSc, such as extracellular matrix remodeling, cell-cell interactions, and metabolism. Subsequently, two critical genes (ENHO and NOX4) were identified by LASSO and SVM-RFE. ENHO was found down-regulated while NOX4 was up-regulated in skin of SSc patients and their expression levels were validated by above three datasets and our cohort. Notably, these differential expressions were more pronounced in patients with diffuse cutaneous SSc than in those with limited cutaneous SSc. Next, we developed a novel diagnostic model for SSc using ENHO and NOX4, which demonstrated strong predictive power in above three cohorts and in our own cohort. Furthermore, immune infiltration analysis revealed dysregulated levels of various immune cell subtypes within early SSc skin specimens, and a negative correlation was observed between the levels of ENHO and Macrophages M1 and M2, while a positive correlation was observed between the levels of NOX4 and Macrophages M1 and M2. Conclusion: This study identified ENHO and NOX4 as novel biomarkers that can be serve as a diagnostic prediction model for early detection of SSc and play a potential role in the pathogenesis of the disease.

[Single-cell RNA sequencing combined experimental verifies the core genes of dendritic cells in chronic obstructive pulmonary disease].

Objective Single-cell RNA sequencing (scRNA-Seq) and experimental verifies core genes of dendritic cells in chronic obstructive pulmonary disease (COPD). Methods scRNA-seq data GSE173896 and chip data GSE38974 were extracted from the Gene Expression Omnibus (GEO) database. GSE173896 was used to perform quality control, batch correction, dimensionality reduction clustering, cell type annotation and dendritic cell differentially expressed genes (DC-DEGs) identification. DEGs from the analysis of GSE38974 were intersected with DC-DEGs to obtain the common DC-DEGs. The diagnostic efficacy of the common DC-DEGs for COPD and their enrichment analysis were conducted. The correlation of the common DC-DEGs with activated dendritic cell (DCs), plasmacytoid dendritic cell (pDCs) and type 17 T helper(Th17) cells were analyzed. The mRNA expression level of the common DC-DEGs in the lung tissue of emphysema mice was verified. Results From GSE173896, 18 DC-DEGs were obtained between groups and from GSE38974, 646 DEGs were obtained. The intersection of the two resulted in 3 common DC-DEGs, including interleukin 1 receptor antagonist 1 (IL1RN), S100 calcicum-binding protein A8 (S100A8) and S100A9. Their respective area under curve (AUC) values were 0.841, 0.804 and 0.966. The GO and KEGG enrichment analysis mainly concentrated on chronic inflammatory response, collagen-containing extracellular matrix, receptor for advanced glycation end products (RAGE) binding, Toll-like receptor (TLR) binding and interleukin 17 (IL-17) signaling pathway. IL1RN, S100A8 and S100A9 were positively correlated with activated DCs, pDCs and Th17 cells. The results showed that the mRNA relative expression levels of IL1RN, S100A8 and S100A9 were up-regulated in the lung tissue of emphysema mice. Conclusion IL1RN, S100A8 and S100A9 may be the core genes of DCs in the pathogenesis of COPD, which potentially provide targets and a theoretical basis for subsequent COPD immunotherapy.

A meta-analysis of the clinical significance of neutrophil-to-lymphocyte ratios in interstitial lung disease.

Interstitial lung disease (ILD) is a group of diffuse parenchymal infiltrating diseases of different etiologies. The neutrophil-to-lymphocyte ratio (NLR) can reflect ILD's existence, progression, and prognosis and is currently regarded as a promising biological marker. This meta-analysis assessed elevated NLR levels in ILD for their predictive value. From inception to July 27, 2022, the Scopus, Cochrane Library, Web of Science, Embase, and PubMed databases were checked thoroughly. We used the weighted mean difference (WMD) and 95% confidence interval (CI) to compare blood NLR values between groups. We examined the relationship between poor prognoses and elevated NLR concentrations in ILD patients using odds ratios (ORs) and 95% CI. After initially including 443 studies, 24 were ultimately analyzed. Fifteen studies(ILD:n = 2,912, Non-ILD: n = 2,868) revealed that the NLR values in the ILD group were relatively high (WMD = 0.61, 95% CI 0.43-0.79, p = 0.001). Eight articles (with poor prognoses: n = 407, without poor prognoses: n = 340) indicated that ILD patients with poor prognoses had higher NLR values (WMD = 1.33, 95% CI 0.32-2.33, p = 0.01). This distinction was especially noticeable in patients with the connective tissue disease (CTD)associated with ILD subgroup (WMD = 3.53, 95% CI 1.54-5.51, p = 0.0005). The pooled OR for increased NLR levels forecasting poor prognoses of ILD was 1.09 (95% CI 1.03-1.15, p = 0.0008). Increasing blood NLR values have clinical significance and application value for detecting ILD and predicting its poor prognosis, especially in CTD patients.

Identification of immune-related diagnostic markers in primary Sjögren's syndrome based on bioinformatics analysis.

Background: Primary Sjögren's syndrome (pSS) is a relatively common diffuse connective tissue disease that often invades exocrine glands, such as the lacrimal and salivary glands, and manifests as dry eyes and dry mouth. At present, the molecular mechanism of pSS is not clear. This study was designed to explore the internal mechanism of pSS from the gene level and screen out the immune-related diagnostic markers of pSS. Methods: The gene expression profiles GSE84844, GSE7451, and GSE40611 were downloaded from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) were identified with R software. Then, the DEGs were intersected with the immune genes obtained from the ImmPort database to acquire differentially expressed immune-related genes (DEIRGs), and functional enrichment analyses were performed. The DEIRGs were screened through the least absolute shrinkage and selection operator (LASSO) logistic regression algorithm to obtain the optimal immune-related genes (IRGs). Expression levels of the optimal IRGs were verified by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) to obtain the key genes. Next, gene chips GSE7451 and GSE40611, from other tissues, were selected as the training sets to verify the sensitivity and specificity of the diagnosis of the key genes by receiver operating characteristic (ROC) analysis. Results: A total of 54 DEIRGs were obtained. The functional enrichment analysis results showed that they play an important role in immune and inflammatory responses. Nine optimal IRGs were screened from the DEIRGs by the LASSO logistic regression algorithm. After qRT-PCR verification, eight out of nine optimal IRGs (IL-18, JAK2, TBK1, EED, TNFSF10, TNFSF13B, CYSLTR1, and ICOS) were significantly highly expressed in pSS patients and were defined as key genes. ROC analysis identified that TNFSF13B and CYSLTR1 had high sensitivity and specificity. Finally, the lack of previous research on EED and CYSLTR1 in pSS suggests that these IRGs may be regarded as new gateways to explore the diagnosis and pathogenesis of pSS. Conclusions: The key DEIRGs play a decisive role during the occurrence and development of pSS.

B Cell IL-4 Drives Th2 Responses In Vivo, Ameliorates Allograft Rejection, and Promotes Allergic Airway Disease.

B cells can be polarized to express various cytokines. The roles of IFNγ and IL-10, expressed respectively by B effector 1 (Be1) and Bregs, have been established in pathogen clearance, tumor growth, autoimmunity and allograft rejection. However, the in vivo role of B cell IL-4, produced by Be2 cells, remains to be established. We developed B-IL-4/13 iKO mice carrying a tamoxifen-inducible B cell-specific deletion of IL-4 and IL-13. After alloimmunization, B-IL-4/13 iKO mice exhibited decreased IL-4+ Th2 cells and IL-10+ Bregs without impact on Th1, Tregs, or CD8 T cell responses. B-IL-4/13 iKO mice rejected islet allografts more rapidly, even when treated with tolerogenic anti-TIM-1 mAb. In ovalbumin-induced allergic airway disease (AAD), B-IL-4/13 iKO mice had reduced inflammatory cells in BAL, and preserved lung histology with markedly decreased infiltration by IL-4+ and IL-5+ CD4+ T cells. Hence, B cell IL-4 is a major driver of Th2 responses in vivo which promotes allograft survival, and conversely, worsens AAD.

B cell-activating factor and its targeted therapy in autoimmune diseases.

B cells play a pivotal role in the pathogenesis of autoimmune disease (AD) by the production of autoantibodies, secretion of cytokines and presentation of autoantigens. As a pro-survival factor mainly produced by myeloid cells, B cell-activating factor (BAFF) maintains B cell maturation and homeostasis at various B cell differentiation stages. Under autoimmune conditions, BAFF acts on autoreactive B cells that have escaped checkpoint apoptosis from negative selection. Numerous studies have shown increased levels of BAFF in patients with ADs and in mouse models with ADs wherein the production of autoantibodies is a prominent feature of immunopathology. Compelling evidence has indicated a key function of BAFF in driving autoreactive B cell response during autoimmune progression. Recent clinical studies have demonstrated BAFF as a therapeutic target in various ADs. Here, we review recent findings on BAFF expression and its effector mechanisms in autoimmune pathogenesis as well as newly developed therapeutic targeting of BAFF in the treatment of ADs.

Interferon regulatory factor 1 (IRF-1) downregulates Checkpoint kinase 1 (CHK1) through miR-195 to upregulate apoptosis and PD-L1 expression in Hepatocellular carcinoma (HCC) cells.

BACKGROUND: CHK1 is considered an oncogene with overexpression in numerous cancers. However, CHK1 signalling regulation in hepatocellular carcinoma (HCC) remains unclear. METHODS: CHEK1 mRNA, protein, pri-miR-195 and miR-195 expression in HCC tissue was determined by qPCR, WB and IF staining assay. Survival analyses in HCC with high- and low-CHEK1 mRNA expression was performed using TCGA database. Relative luciferase activity was investigated in HCC cells transfected with p-CHEK1 3'UTR. Apoptosis was detected by TUNEL assay. NK and CD8+ T cells were analysed by flow cytometry. RESULTS: CHK1 is increased in human HCC tumours compared with non-cancerous liver. High CHK1 predicts worse prognosis. IFN-γ suppresses CHK1 via IRF-1 in HCC cells. The molecular mechanism of IRF-1 suppressing CHK1 is post-transcriptional by promoting miR-195 binding to CHEK1 mRNA 3'UTR, which exerts a translational blockade. Upregulated IRF-1 inhibits CHK1, which induces apoptosis of HCC cells. Likewise, CHK1 inhibition augments cellular apoptosis in HCC tumours. This effect may be a result of increased tumour NK cell infiltration. However, IRF-1 expression or CHK1 inhibition also upregulates PD-L1 expression via increased STAT3 phosphorylation. CONCLUSIONS: IRF-1 induces miR-195 to suppress CHK1 protein expression. Both increased IRF-1 and decreased CHK1 upregulate cellular apoptosis and PD-L1 expression in HCC.

Interferon regulatory factor 1(IRF-1) activates anti-tumor immunity via CXCL10/CXCR3 axis in hepatocellular carcinoma (HCC).

Interferon regulatory factor 1 (IRF-1) is a tumor suppressor gene in cancer biology with anti-proliferative and pro-apoptotic effect on cancer cells, however mechanisms of IRF-1 regulating tumor microenvironment (TME) in hepatocellular carcinoma (HCC) remain only partially characterized. Here, we investigated that IRF-1 regulates C-X-C motif chemokine 10 (CXCL10) and chemokine receptor 3 (CXCR3) to activate anti-tumor immunity in HCC. We found that IRF-1 mRNA expression was positively correlated with CXCL10 and CXCR3 through qRT-PCR assay in HCC tumors and in analysis of the TCGA database. IRF-1 response elements were identified in the CXCL10 promoter region, and ChIP-qPCR confirmed IRF-1 binding to promote CXCL10 transcription. IRF-2 is a competitive antagonist for IRF-1 mediated transcriptional effects, and overexpression of IRF-2 decreased basal and IFN-γ induced CXCL10 expression. Although IRF-1 upregulated CXCR3 expression in HCC cells, it inhibited proliferation and exerted pro-apoptotic effects, which overcome proliferation partly mediated by activating the CXCL10/CXCR3 autocrine axis. In vitro and in vivo studies showed that IRF-1 increased CD8+ T cells, NK and NKT cells migration, and activated IFN-γ secretion in NK and NKT cells to induce tumor apoptosis through the CXCL10/CXCR3 paracrine axis. Conversely, this effect was markedly abrogated in HCC tumor bearing mice deficient in CXCR3. Therefore, the IRF-1/CXCL10/CXCR3 axis contributes to the anti-tumor microenvironment in HCC.

Transitional B cell cytokines predict renal allograft outcomes.

Early immunological biomarkers that predict rejection and chronic allograft loss are needed to inform preemptive therapy and improve long-term outcomes. Here, we prospectively examined the ratio of interleukin-10 (IL-10) to tumor necrosis factor-α (TNFα) produced by transitional-1 B cells (T1B) 3 months after transplantation as a predictive biomarker for clinical and subclinical renal allograft rejection and subsequent clinical course. In both Training (n = 162) and Internal Validation (n = 82) Sets, the T1B IL-10/TNFα ratio 3 months after transplantation predicted both clinical and subclinical rejection anytime in the first year. The biomarker also predicted subsequent late rejection with a lead time averaging 8 months. Among biomarker high-risk patients, 60% had early rejection, of which 48% recurred later in the first posttransplant year. Among high-risk patients without early rejection, 74% developed rejection later in the first year. In contrast, only 5% of low-risk patients had early and 5% late rejection. The biomarker also predicted rejection in an External Validation Set (n = 95) and in key patient subgroups, confirming generalizability. Biomarker high-risk patients exhibited progressively worse renal function and decreased 5-year graft survival compared to low-risk patients. Treatment of B cells with anti-TNFα in vitro augmented the IL-10/TNFα ratio, restored regulatory activity, and inhibited plasmablast differentiation. To conclude, the T1B IL-10/TNFα ratio was validated as a strong predictive biomarker of renal allograft outcomes and provides a rationale for preemptive therapeutic intervention with TNF blockade.

Interferon regulatory factor 1 (IRF-1) and IRF-2 regulate PD-L1 expression in hepatocellular carcinoma (HCC) cells.

The objective response rate of immune checkpoint blockade (ICB) in hepatocellular carcinoma (HCC) with anti PD-L1/PD-1 therapy is low. Discovering the signaling pathways regulating PD-L1 might help to improve ICB response rates. Here, we investigate transcription factors IRF-1 and IRF-2 signaling pathways regulating PD-L1 in HCC cells. In vivo studies show that IRF-1 and PD-L1 mRNA expression in human HCC tumors are significantly repressed compared with noncancerous background liver. IRF-1, IRF-2, and PD-L1 mRNA expression correlated positively in HCC tumors. Increased IRF-1 mRNA expression was observed in patients with well-differentiated or early stage HCC tumors. In vitro studies show that IFN-γ induces PD-L1 mRNA and protein expression through upregulation of IRF-1 in mouse and human HCC cells. IRF-1, IRF-2, and PD-L1 mRNA expression is upregulated in murine HCC by co-culture with effector T cells from spleen cells incubated with anti-CD3/CD28 antibodies. IRF-2 over-expression down-regulates IFN-γ induced PD-L1 promoter activity and protein levels in a dose-dependent manner. We identify two IRF-1 response elements (IRE1/IRE2) in the upstream 5'-flanking region of the CD274 (PD-L1) gene promoter. Site-directed mutagenesis shows both IRE1 and IRE2 are functional in transfection promoter assays. IRF-1 traditionally functions as tumor suppressor gene. However, these novel findings show a complex role for IRF-1 which upregulates PD-L1 in the inflammatory tumor microenvironment. IRF-1 antagonizes IRF-2 for binding to the IRE promoter element in PD-L1 which gives new insight to the regulation of PD-L1/PD-1 pathways in HCC ICB therapy.

Effects of thalidomide on Th17, Treg cells and TGF-ß1/Smad3 pathway in a mouse model of systemic sclerosis.

OBJECTIVE: To evaluate the immune regulatory and anti-fibrosis function of thalidomide (Thal) in systemic sclerosis (SSc), we investigated the effects of Thal on: (a) Th17 and Treg cell production; (b) related factors expression; and (c) transforming growth factor (TGF)-ß1/Smad3 pathway, using a mouse model of SSc. METHODS: Forty female BALB/c mice were randomly divided into a normal control (NC) group, SSc group (bleomycin [BLM]-induced experimental SSc), BLM + Thal (10 mg/kg/day) group, BLM + Thal (20) group, and BLM + Thal (30) group. Thal was administered a day after BLM. At the end of the animal experiments, mouse tissues were collected for detection of pathological changes and hydroxyproline content. Flow cytometry, real-time polymerase chain reaction, enzyme-linked immunosorbent assay, immunohistochemistry, Western blot and other methods were used to measure Th17, Treg cell population and their related factors, as well as TGF-ß1/Smad3 pathway expression. RESULTS: Thal treatment: (a) reduced skin, and pulmonary tissue fibrosis, inflammation score, and hydroxyproline content (P < .001) in BLM-induced SSc mice; (b) reduced the percentages of Th17 cells and associated interleukin (IL)-17A expression (both P < .05) but increased the percentages of Treg cells and its transcription factor Foxp3 expression (both P < .05); (c) correlation analysis found positive correlations between Th17/Treg ratio, the inflammatory score of the skin and pulmonary tissues, hydroxyproline content, and type I collagen messenger RNA expression (r = .8546, .8656, .6902, .6807, .8118, and .8424, respectively, P < .01); (d) Thal inhibited TGF-ß1 expression and Smad3 phosphorylation (both P < .05); (e) TGF-ß1 was positively correlated with the IL-17A and Th17/Treg ratio (r = .5856, P = .005; r = .6684, P = .0107, respectively). CONCLUSION: Thal can effectively prevent skin and pulmonary tissue fibrosis in a mouse model of SSc through the TGF-ß1/Smad3 signaling pathway and can rectify the distortion of the Th17/Treg balance in SSc by potentially regulating Th17 and Treg cell production, as well as their related factors expression.

p53 predominantly regulates IL-6 production and suppresses synovial inflammation in fibroblast-like synoviocytes and adjuvant-induced arthritis.

BACKGROUND: Dominant-negative somatic mutations of p53 has been identified in the synovium of patients with rheumatoid arthritis (RA), in which interleukin (IL)-6 has been established as a pivotal inflammatory cytokine. The aim of this study was to clarify the significance of p53 in the longstanding inflammation in RA by modulating IL-6. METHODS: We established adjuvant-induced arthritis (AIA) in Lewis rats and treated them with p53 activator, and then analyzed the histopathology of the synovium and IL-6 expression. Human fibroblast-like synoviocytes (FLS) were cultured and transfected with p53-siRNA or transduced with adenovirus (Ad)-p53, and then assessed with MTT, TUNEL staining, and luciferase assay. IL-1ß, tumor necrosis factor (TNF)-α and IL-17 were used to stimulate FLS, and subsequent IL-6 expression as well as relevant signal pathways were explored. RESULTS: p53 significantly reduced synovitis as well as the IL-6 level in the AIA rats. It controlled cell cycle arrest and proliferation, but not apoptosis. Proinflammatory cytokines inhibited p53 expression in FLS, while p53 significantly suppressed the production of IL-6. Furthermore, IL-6 expression in p53-deficient FLS was profoundly reduced by NF-kappaB, p38, JNK, and ERK inhibitors. CONCLUSION: Our findings reveal a novel function of p53 in controlling inflammatory responses and suggest that p53 abnormalities in RA could sustain and accelerate synovial inflammation mainly through IL-6. p53 may be a key modulator of IL-6 in the synovium and plays a pivotal role in suppressing inflammation by interaction with the signal pathways in RA-FLS. Interfering with the p53 pathway could therefore be an effective strategy to treat RA.