Fig. 6.

B cell homing and transcription factors constitute a pro-inflammatory micro milieu in ASyS patients’ skeletal muscle. Representative stains of muscle biopsies from ASyS patients with corresponding serological status. Monocytic cells in the inflammatory infiltrate of the skeletal muscles in ASyS express CXCL12 (a), CXCL13 (b) APRIL (c) and BAFF (d). Scale bar 100 µm. Immunohistological co-stains for immune cells with CXCL12 (e), CXCL13 (f), APRIL (g) and BAFF (h) are displayed as representative pictures, scale bar 25 µm. CXCL12 is co-expressed in CD68⁺ macrophages, CD8⁺ T cells and CD20⁺ B cells, while CXCL13 is co-expressed in CD68⁺ macrophages and CD8⁺ T cells. Additionally, CD4⁺ T cells express APRIL and BAFF, which are also found in CD20⁺ B cells. Analysis of gene expression of CCR7, CXCL12 and CXCR4 (i), CXCL13 and CXCL5 (j), as well as APRIL and BAFF (k) are displayed as box-plot indicating the log10 fold change of ASyS compared to NDC for corresponding serological groups, as well as in IMNM patients, which serve as the disease control (DC) group (i, j, k). Significant differences comparing ASyS or DC with NDC are indicated by the corresponding p-value above each plot. Significant differences between serological groups is indicated by the corresponding p-value connecting groups by dotted lines. The Kruskal–Wallis one-way analysis of variance with Dunn’s multiple comparison test was used. The level of significance was set to p < 0.05. *p < 0.05, **p < 0.01, ***p < 0.001. ASyS  Anti-synthetase syndrome, DC  disease control, IMNM  immune-mediated necrotizing myopathy, NDC  non-diseased control