Antigen-presenting autoreactive B cells activate regulatory T cells and suppress autoimmune arthritis in mice

The systemic lupus erythematosus-associated NCF190H allele synergizes with viral infection to cause mouse lupus but also limits virus spread

Studying how single nucleotide polymorphisms (SNPs) crosstalk with non-autologous factors to cause complex autoimmune diseases is challenging. An amino acid replacement in the neutrophil cytosolic factor 1 (NCF1-339/NCF1R90H) leading to lower reactive oxygen species induction has been reported as the major SNP for systemic lupus erythematosus (SLE). Here we show that infection with the murine norovirus (MNV) contributes to the induction of lupus in Ncf190H mice. Mutant NCF190H upregulates the IFN-α/JAK1/STAT1 pathway in macrophages and anti-MNV-antibody production. In parallel, the MNV infection of NCF190H mice upregulates Toll-like receptor 7 in macrophages, plasmacytoid dendritic cells and B220+ splenocytes, thereby promoting germinal center formation and lupus-associated autoantibodies production. These compounded effects lead to protection against MNV infection but also glomeruloneph ritis with proteinuria and lupus arthritis in the absence of chemical inducers such as pristane. Our data thus suggest that this SLE-associated SNP, NCF190H, synergizes with MNV infection to induce the development of mouse lupus.

PD-1/PD-L1 axis induced host immunosuppression via PI3K/Akt/mTOR signalling pathway in piglets infected by Glaesserella Parasuis

Glaesserella parasuis, an important respiratory bacterial pathogen, causes Glässer's disease in piglets, with potential immunosuppression. We established a piglet infection model and explored the immunosuppression mechanism to improve our understanding of the host immune response to G. parasuis. Twenty piglets were randomly divided into two groups (n = 10). The infection group was intraperitoneally challenged with 2 × 108 CFU of G. parasuis in 2 mL TSB. The control group was intraperitoneally injected with equivalent TSB. After 72 h, the piglets were sacrificed, and spleen tissue was collected. PD-1/PD-L1 expression was determined. The splenocytes were isolated to detect CD3+ T, CD3+CD4+ T, CD3+CD8+ T and CD3-CD21+cell differentiation. Via data-independent acquisition (DIA), we compared the proteomics of healthy and infected spleen tissues. Glaesserella parasuis modified CD3+ T, CD3+CD4+ T, CD3+CD8+ T and CD3-CD21+ cell differentiation and PD-1/PD-L1 expression in the spleen. The infection group had 596 proteins with significant differences in expression, of which 301 were significantly upregulated and 295 downregulated. Differentially expressed proteins (DEPs) were mainly related to immune responses. This is the first study on PD-1/PD-L1 expression in the spleen associated with immunosuppression in a piglet model to explore the protein changes related to immune responses via DIA.