METTL14-m6A-FOXO3a axis regulates autophagy and inflammation in ankylosing spondylitis.

The role of m6A in ankylosing spondylitis (AS) remains largely obscure. In this study, we found that m6A modification was decreased in T cells of AS, and the abnormal m6A modification was attributed to the downregulation of methyltransferase-like 14 (METTL14). METTL14 exerted a critical role in regulating autophagy activity and inflammation via targeting Forkhead box O3a (FOXO3a). Mechanistically, the loss of METTL14 decreased the expression of FOXO3a, leading to the damage of autophagic flux and the aggravation of inflammation. Inversely, the forced expression of METTL14 upregulated the expression of FOXO3a, thereby activating autophagy and alleviating inflammation. Furthermore, our results revealed that METTL14 targeted FOXO3a mRNA and regulated its expression and stability in a m6A-dependent manner. These findings uncovered the functional importance of m6A methylation mechanisms in the regulation of autophagy and inflammation, which expanded our understanding of this interaction and was critical for the development of therapeutic strategies for AS.

PRICKLE1 gene methylation and abnormal transcription in Chinese patients with ankylosing spondylitis.

BACKGROUND: Ankylosing spondylitis (AS) is a common inflammatory arthritis without a reliable biomarker. The role of methylation and mRNA expression of PRICKLE1 promoter in the pathogenesis of ankylosing spondylitis remains unclear. METHODS: A two-stage case-control design was used to detect the characteristics of methyl group and transcriptome of PRICKLE1 gene in Ankylosing spondylitis. The methylation degree of PRICKLE1 gene promoter region was tested by phosphate-sequencing, and further analyzed whether there was significant difference in methylation level of PRICKLE1 gene. The expression levels of PRICKLE1 mRNA in 50 AS patients and 50 healthy controls were detected by real-time quantitative PCR (RT-qPCR). RESULTS: Compared with healthy control group, the intensity of methylation in 4 ponds of PRICKLE1 in patients with Ankylosing spondylitis was low, and the mRNA levels were overexpressed (P = 0.017). ROC results showed that the sensitivity of PRICKLE1 was 68.67% and specificity was 71.43%. CONCLUSION: There is a significant change in the concentration of serum PRICKLE1 mRNA​in patients with Ankylosing spondylitis, and the degree of gene methylation is significantly reduced, suggesting that PRICKLE1 gene maybe involved in the pathogenesis of Ankylosing spondylitis, which may be useful for predicting the occurrence of AS and finding new early screening indicators.

The combined effect of heavy metals and polycyclic aromatic hydrocarbons on arthritis, especially osteoarthritis, in the U.S. adult population.

The evaluation of heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) impact on arthritis is usually limited to the analysis of the arthritis subtype (rheumatoid arthritis, RA), whereas studies on osteoarthritis (OA) are relatively sparse. Furthermore, the combined effect of HMs and PAHs co-exposure on arthritis also has rarely been analyzed. Herein, we aimed to comprehensively estimate the association between HMs and PAHs (three blood HMs and six urinary PAHs metabolites) co-exposure and arthritis. Using data from the National Health and Nutrition Examination Survey (NHANES), 2003-2016, we included 9735 adults, of whom 2464 had total arthritis, 1371 had OA, and 468 had RA. The logistic regression model was conducted to estimate the single effect of HMs and PAHs on arthritis. Moreover, weighted quantile sum (WQS) regression, quantile-based g computation (qgcomp), and Bayesian kernel machine regression (BKMR) were separately performed to assess the combined effect of HMs and PAHs co-exposure on arthritis. In the single-exposure analyses, cadmium (Cd) and lead (Pb) statistically grew the risk of total arthritis, OA, and RA. Among PAHs, 1-hydroxynaphthalene (1-NAP) and 3-hydroxyfluorene (3-FLU) showed a positive association with total arthritis, OA, and RA. Meanwhile, 2-NAP also was significantly associated with total arthritis. 2-NAP, 2-FLU, and 1-hydroxyphenanthrene (1-PHE) also were significantly associated with RA. Furthermore, the three complementary models consistently demonstrated that co-exposure to high levels of HMs and PAHs was positively associated with total arthritis, OA, and RA risk. The above associations were more obvious in young and medium-aged people. Interestingly, BKMR analyses indicated that 1-NAP might interact with Cd and 3-FLU in total arthritis, while Pb might interact with Cd in OA. Therefore, this study provided novel evidence that co-exposure to HMs and PAHs positively correlated with arthritis, especially OA, and these results were worthy of further prospective studies.

DNA methylation and transcriptional profiles of IRF5 gene in ankylosing spondylitis: A case-control study.

BACKGROUND: Interferon regulatory factor 5 (IRF5) plays an important role in the inflammation and immune responses, but its association with ankylosing spondylitis (AS) is under investigated. We aimed to examine the association of IRF5 promoter methylation patterns and transcript levels with the susceptibility to AS. METHODS: A total of 60 AS patients and 60 healthy controls were included in this study. We used the bisulfite conversion to detect the DNA methylation pattern of IRF5 promoter in whole blood, and the quantitative real-time PCR (qRT-PCR) to detect the relative mRNA expression level in peripheral blood mononuclear cells (PBMCs). RESULTS: The overall methylation level of IRF5 promoter was lower in AS patients compared to healthy controls (P < 0.001). The methylation level of IRF5 promoter was negatively correlated with mRNA level (P = 0.005). The results of receiver operating characteristic curve (ROC) showed that the area under the curve (AUC) was 0.810 (P < 0.001), and the sensitivity and specificity were 71.67% and 85.00%, respectively. There were significant differences between the severe dysfunction group and healthy control group, and between the mild dysfunction group and healthy control group (P = 0.006 and P < 0.001, respectively). Only CRP was significantly correlated with mRNA relative level, while the others were not significant. CONCLUSION: These findings indicate that IRF5 methylation profile may be involved in the pathological process of AS, and that it may help identify AS patients.

Telomere length in patients with osteoarthritis: a systematic review and meta-analysis.

BACKGROUND: Telomere length (TL) as a biomarker of aging was associated with many age-related diseases. The relationship between TL and osteoarthritis (OA), the most common form of joint diseases, had been investigated in a number of studies, but with the result inconsistent. AIMS: The purpose of this study was to systematically evaluate the relationship between TL and OA. METHODS: Until January 1, 2021, PubMed, Web of Science and Cochrane Library were comprehensively retrieved for relevant literatures. Quality of included literature was assessed using the Newcastle-Ottawa Scale (NOS) assessment scale. The pooled standard mean difference (SMD) with 95% confidence interval (CI) of Leukocytes TL was calculated using random-effect model. Subgroup analysis and meta-regression were used to investigate the potential source of heterogeneity. RESULTS: Six original studies containing 678 OA patients and 1457 healthy controls were included in this meta-analysis. All six included studies were case-control designed. Pooled results showed that patients with OA had a shorter TL in peripheral blood leukocytes (PBLs) compared with healthy controls, (SMD = - 0.32, 95% CI - 0.57 to - 0.06, Z = - 2.45, P = 0.014). Subgroup and meta-regression analysis showed that sex ratio and body mass index (BMI) were possible sources of heterogeneity. Publication bias was not observed. CONCLUSION: The TL of PBLs in patients with OA was shorter than that of healthy controls, suggesting that PBLs TL may be closely associated with the pathogenesis and progression of OA.

Astragalus-mediated stimulation on antigen-presenting cells could result in higher IL-21 production from CXCR5+ Tfh-like cells and better IL-21-mediated effector functions.

T cells in renal cell carcinoma (RCC) patients display multiple features of impairment and exhaustion. Here, we hypothesize that Astragalus membranaceus, a herbal medicine commonly used to accompany chemotherapy, might have adjuvating effects on T cells from RCC patients. To investigate this, circulating T cells from healthy individuals and RCC patients were cocultured ex vivo with aqueous extract from Astragalus. Functional characteristics of T cells in the absence and presence of Astragalus extract were then compared. We first identified a downregulation of IL-21 expression in RCC patients in association with a functional dysregulation of CXCR5+ Tfh-like cells. Astragalus extract could significantly increase IL-21 expression in a dose-dependent manner. This Astragalus-mediated effect depended on the presence of antigen-presenting cells (APCs), as purified CXCR5+ Tfh-like cells presented little IL-21 upregulation following Astragalus stimulation. APCs primed by Astragalus extract also promoted IL-21 expression from Tfh-like cells. Interestingly, Astragalus-stimulated Tfh-like cells presented enhanced helper function and resulted in higher humoral responses and better CD8 T cell survival. This effect was dependent on the presence of IL-21. Overall, these data indicated that Astragalus could enhance IL-21 production and effector function from CXCR5+ Tfh-like cells in a manner that depended on the presence of APCs.

Association of CTLA-4 (+49 A/G) polymorphism with susceptibility to autoimmune diseases: A meta-analysis with trial sequential analysis.

OBJECTIVES: In recent years, more and more studies have been focusing on the association between Cytotoxic T lymphocyte antigen-4 (CTLA-4) (+49 A/G) gene polymorphism and autoimmune diseases. However, the results of previous studies are still controversial. The meta-analysis is aiming at determining the association in CTLA-4 (+49 A/G) gene rs231775 polymorphism and ankylosing spondylitis (AS), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE). METHODS: We searched PubMed, Web of Science, Chinese National Knowledge Infrastructure (CNKI) and Chinese Biomedical Database (CBM) up to November 2020, use random or fixed-effect models to perform meta-analysis to compare alleles and other genetic models, including homozygous, heterozygous, recessive and dominant models. The odds ratio (OR) with a 95% confidence interval (95% CI) was used to assess the correlation between CTLA-4 (+49 A/G) gene polymorphism and the genetic affectability of AS, RA, and SLE. Meanwhile, we used sequential trial analysis (TSA) to analyze the reliability of the results. Finally, we searched the relevant data of genome-wide association studies (GWAS) to further verify the accuracy of the experimental results. RESULTS: 47 studies with 11,893 cases and 12,032 healthy controls were included. The rs231775 G allele was relevant to high risk of autoimmune disease over all people (P < 0.05). The G allele of rs231775 was significantly related to RA susceptibility (P < 0.05), but not with AS or SLE. Subgroup analysis by ethnicity indicated that rs231775 G allele was closely related to RA in Caucasian populations and Mongolian populations (P < 0.05). A strong connection within rs231775 G allele and AS affectability was uncovered in Caucasian populations (P < 0.05). The analysis of the TSA shows that the meta-analysis can draw the conclusion. CONCLUSION: CTLA-4 (+49 A/G) gene rs231775 G allele increases the risk of autoimmune diseases in Caucasian populations. And it also increases the risk of RA in Caucasian and Mongolian populations. More sample size and more elaborately designed studies are needed to elucidate the relationship in CTLA-4 (+49 A/G) gene rs231775 G allele and autoimmune diseases, especially AS, SLE.

Lipoxin A4 ameliorates alveolar fluid clearance disturbance in lipopolysaccharide-induced lung injury via aquaporin 5 and MAPK signaling pathway.

BACKGROUND: A characteristic of acute lung injury (ALI) is the inflammatory damage of alveolar fluid transport. Lipoxins are endogenous lipids involving in the resolution of inflammation. It is found that lipoxin A4 (LXA4) has the distinct properties to improve the anti-edema and pro-resolution function in inflammation. Since aquaporins (AQPs) have essential roles in the integrity of barrier function during fluid transport, especially AQP5 in the maintaining of the epithelium permeability, the current study is aimed to evaluate the potential role of LXA4 in regulating alveolar fluid clearance (AFC) during fluid transport and the corresponding change of AQP5 in the lung. METHODS: ALI was induced by the lipopolysaccharide (LPS) intraperitoneal injection, and LXA4 treatment was given 8 hours after LPS administration. We investigated changes in the capacity of AFC, pro-inflammatory cytokine concentrations in bronchoalveolar lavage fluid (BALF) and the severity of ALI. Then AQP5 expression in lung tissue and potential regulatory pathways in LPS-induced ALI was explored. RESULTS: LXA4 treatment was found to inhibit AFC capacity, inflammatory cytokine release, partially, alleviate ALI severity, and restored AQP5 expression partially. Additionally, we found that LXA4 played a protective role by the inhibition of the phosphorylation of p38 and JNK. CONCLUSIONS: In summary, our results suggest that LXA4 plays a protective role in lipopolysaccharide-induced ALI by restoring AFC capacity and upregulating AQP5 expression and inhibiting the phosphorylation of p38 and JNK. These findings suggest potential new mechanism of LXA4 as anti-inflammation therapy for the impairment of alveolar fluid transport in ALI.