CX3CL1-induced CD16+ monocytes extravasation in myeloperoxidase-ANCA-associated vasculitis correlates with renal damage

Immune Landscape Variation in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis Circulation Before and After Plasmapheresis by Single-Cell Transcriptome

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of autoimmune diseases characterized by inflammation and destruction of small blood vessels. AAV could be fatal if left untreated. Prompt diagnosis and treatment are crucial to protect AAV-related organs and tissue. Plasmapheresis, a therapeutic intervention aimed at removing harmful substances from the blood, devotes benefits to AAV treatment. However, the specific immune mechanism underlying its effectiveness remains unclear. In our research, we used single-cell RNA sequencing (scRNA-seq) to study the variation of peripheral blood mononuclear cells (PBMCs) before and after plasmapheresis in AAV patients. From this work, we explored a novel method for monocyte classification. In addition, flow cytometry was used to detect the relationship between the monocyte clusters and AAV activity under the new monocyte clustering method. Our scRNA-seq results revealed significant changes in monocyte clusters following treatment, which could be classified into three clusters (CD14+ monocytes, FCGR1A+ monocytes, and FCGR3A+ monocytes). In addition, our flow cytometry results showed that FCGR3A+ (CD16+) monocytes were positively correlated with AAV activity, whereas FCGR1A+ (CD16-CD64+) monocytes were negatively correlated with AAV activity. This may be related to the different biological effects of CD16 and CD64 on monocytes after interacting with the Fc region of ANCAs. In conclusion, our research sheds light on the immune landscape of AAV before and after plasmapheresis, identifying specific monocyte clusters linked to disease activity. These findings offer insights for novel monitoring methods and therapeutic targets in AAV.

The association between fractalkine/CX3CR1 axis with IgA vasculitis and nephritis

BACKGROUND

The study investigated whether the fractalkine/CX3CR1 axis is associated with the presence and severity of IgA vasculitis (IgAV) and IgA vasculitis nephritis (IgAVN) in children.

METHODS

We included 59 children with IgAV, 42 children with IgAVN (including 18 children with kidney biopsy), 26 plasma controls and 8 kidney controls. Clinical pathological data were collected, and the fractalkine/CX3CR1 axis and macrophage expression in the circulation and kidneys were detected.

RESULTS

Circulating fractalkine/CX3CR1 axis expression was significantly upregulated in children with IgAV and IgAVN compared to healthy controls. Plasma fractalkine levels and the proportion of CX3CR1+ monocytes were significantly higher in children with IgAVN than in those with IgAV, and the kidney expression of fractalkine/CX3CR1 axis and CD68 were significantly increased in the IgAVN group relative to normal controls, especially in children with IgAVN with more severe ISKDC pathological grading. Additionally, kidney levels of fractalkine, CX3CR1, and CD68 exhibited significant positive correlations with tubulointerstitial grading and serum creatinine levels.

CONCLUSION

The expression of fractalkine/CX3CR1 axis is associated with the presence and severity of IgAV and IgAVN. Our findings support further investigation of fractalkine/CX3CR1 as a target for future therapies in IgAV and IgAN.

IMPACT

The expression of plasma fractalkine/CX3CR1 axis is associated with the presence and severity of IgAV and IgAVN. The expression of kidney fractalkine/CX3CR1 axis and macrophage are upregulated in IgAVN, which is closely associated with poorer kidney function and more severe kidney pathology. Our findings support further investigation of fractalkine/CX3CR1 as a target for future therapies in IgAV and IgAVN.

Integrated bioinformatic analysis of the shared molecular mechanisms between ANCA-associated vasculitis and atherosclerosis

BACKGROUND AND OBJECTIVE

Accumulated evidence supports the tendency of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis(AAV) to coexist with atherosclerosis (AS). However, the common etiology of these two diseases remains unclear. This study aims to explore the mechanisms underlying the concurrent occurrence of ANCA and AS.

METHODS

Microarray data of AAV and AS were examined in a comprehensive gene expression database. Weighted gene co-expression network analysis (WGCNA) and differential gene expression analysis (GEO2R) were performed to identify common genes between AAV and AS. Based on the co-expressed genes, functional enrichment analysis, protein-protein interaction (PPI) network analysis, and identification of hub genes (HGs) were conducted. Subsequently, co-expression analysis of HGs was performed, and their expression and diagnostic value were validated. We further explored immune cell infiltration and analyzed the correlation between HGs and infiltrating immune cells. Finally, the reliability of the selected pathways was verified.

RESULTS

The results of the common gene analysis suggest that immune and inflammatory responses may be common features in the pathophysiology of AAV and AS. Through the interaction of different analysis results, we confirmed five HGs (CYBB, FCER1G, TYROBP, IL10RA, CSF1R). The CytoHubba plugin and HG validation demonstrated the reliability of the selected five HGs. Co-expression network analysis revealed that these five HGs could influence monocyte migration. Analysis of immune cell infiltration showed that monocytes in ANCA and M0 macrophages in AS constituted a higher proportion of all infiltrating immune cells, with significant differences in infiltration. We also found significant positive correlations between CYBB, FCER1G, TYROBP, IL10RA, CSF1R, and monocytes/M0 macrophages in AAV, as well as between CYBB, FCER1G, TYROBP, IL10RA, CSF1R, and M0 macrophages in AS.

CONCLUSION

These five HGs can promote monocyte differentiation into macrophages, leading to the concurrent occurrence of AAV and AS. Our study provides insights into the mechanisms underlying the coexistence of AAV and AS.

Causal association between cardiovascular proteins and membranous nephropathy: a bidirectional Mendelian randomization

PURPOSE

Multiple circulating proteins have been reported to participate in human diseases. However, the association between cardiovascular proteins and membranous nephropathy (MN) remained profoundly elusive.

METHODS

A bidirectional Mendelian randomization (MR) analysis was conducted to explore the causal correlation between ninety cardiovascular proteins and MN. Genome-wide association study (GWAS) data of cardiovascular proteins and MN were all from European research. Inverse variance weighted (IVW) was used as the main approach. Moreover, MR-Egger, weighted median, weighted mode, and simple mode were also performed. Cochrane's Q test, MR-Egger, and MR-PRESSO were conducted for sensitivity analysis.

RESULTS

According to IVW method, fatty acid-binding protein and thrombomodulin (TM) were identified as risk factors for MN, while a protective role was detected in tissue-type plasminogen activator. Additionally, MN was associated with an elevated level of macrophage colony-stimulating factor 1, stem cell factor, TM, and tissue factor. Reversely, MN was also correlated with a downregulated level of beta-nerve growth factor, Cathepsin D, hepatocyte growth factor, interleukin-6 receptor subunit alpha, macrophage colony-stimulating factor 1, and myeloperoxidase. In the sensitivity analysis, no significant pleiotropy and heterogeneity was detected.

CONCLUSION

This was the first study to reveal the causal association between cardiovascular proteins and MN. These specific cardiovascular proteins could be novel biomarkers for MN, and is helpful for timely identify the risk of other diseases that might result from MN. However, further clinical studies are needed to confirm our results.

Chemokine expression in sera of patients with microscopic polyangiitis and granulomatosis with polyangiitis

We evaluated chemokine expression and its correlation with disease activity in patients with microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) (MPA/GPA). Serum CCL2, CCL4, CCL19, CXCL1, CXCL2, and CX3CL1 level in 80 patients were analysed using multiple enzyme-linked immunosorbent assays. Correlations between variables were investigated using Pearson's correlation analysis, and receiver operator curve analysis was performed to identify optimal CX3CL1 values in determining active disease. Multivariate logistic regression analysis was done to evaluate predictors of active disease. CCL4 (r = 0.251, p = 0.025), CXCL1 (r = 0.270, p = 0.015), and CX3CL1 (r = 0.295, p = 0.008) significantly correlated with BVAS, while CX3CL1 was associated with five-factor score (r =  - 0.290, p = 0.009). Correlations were revealed between CCL2 and CCL4 (r = 0.267, p = 0.017), CCL4 and CXCL1 (r = 0.368, p < 0.001), CCL4 and CXCL2 (r = 0.436, p < 0.001), and CXCL1 and CXCL2 (r = 0.518, p < 0.001). Multivariate analysis revealed serum CX3CL1 levels > 2408.92 pg/mL could predict active disease (odds ratio, 27.401, p < 0.001). Serum chemokine levels of CCL4, CXCL1, and CX3CL1 showed association with disease activity and especially, CX3CL1 > 2408.92 pg/mL showed potential in predicting active MPA/GPA.