sNASP Mutation Aggravates to the TLR4-Mediated Inflammation in SLE by TAK1 Pathway.

Genetic factors play an important role in the pathogenesis of systemic lupus erythematosus (SLE), and abnormal Toll-like receptor (TLR) signaling pathways are closely related to the onset of SLE. In previous studies, we found that the mutant somatic nuclear autoantigenic sperm protein (sNASP) gene in the mouse lupus susceptibility locus Sle2 can promote the development of lupus model mice, but the mechanism is still unclear. Here, we stimulated mouse peritoneal macrophages with different concentrations of lipopolysaccharide. The results showed that sNASP gene mutations can promote the response of the TLR4-TAK1 signaling pathway but have no significant effect on the TLR4-TBK1 signaling pathway. sNASP mutations enhanced TLR4-mediated nuclear factor-κ-gene binding and mitogen-activated protein kinase activation and IL-6, tumor necrosis factor secretion in murine peritoneal macrophages. Collectively, our study revealed the impact of sNASP gene mutation on the sensitivity of TLR4 receptors in mouse peritoneal macrophages and shed light on potential mechanisms underlying inflammation in autoimmune diseases.

A murine Skint6 W168X allele contributes to autoimmune disease in a transgenic model.

BACKGROUND: The genetic factor is a great driver of systemic lupus erythematosus. A Skint6 W168X allele was previously identified in the murine lupus susceptibility rec1d1 sublocus. The purpose of this study is to investigate the pathogenic role and mechanism of the Skint6 W168X allele in lupus autoimmune disease. METHODS: The gene-editing CRISPR/Cas9 system was used to generate transgenic models with the Skint6 W168X allele. PCR and Sanger's sequencing techniques were applied to mRNA quantification and DNA sequence detection. Flow cytometry was adopted for immunophenotyping. Pathological evaluation of kidneys and lungs was performed using several immunopathological approaches. RESULTS: The transgenic models with the Skint6 W168X allele were created, including B6.Skint6X/X and B6.lpr.Skint6X/X strains. The B6.lpr.Skint6X/X mice showed bigger spleen and lymph nodes, more lymphocytes and effector T cell populations, more severe nephritis with more IgG and C3 deposit in glomeruli as well as worse proteinuria, and more severe lung inflammation than control B6.lpr mice. In addition, a skint6 receptor binding Skint6 peptide was identified from T and B lymphocytes. B6.Skint6X/X mice have lower percentages of skint6 receptor+ T and B cells in spleen than B6 mice. CONCLUSION: The Skint6 W168X allele in murine lupus rec1d1 sublocus was validated to be a pathogenic mutant gene and contributes to autoimmune disease through producing a truncated Skint6 peptide of binding the skint6 receptors on lymphocytes.

A Variant of sNASP Exacerbates Lymphocyte Subset Disorder and Nephritis in a Spontaneous Lupus Model Sle1.Yaa Mouse.

A variant of somatic nuclear autoantigenic sperm protein (sNASP) was identified from the murine lupus susceptibility locus Sle2c1 by whole exome sequencing (WES). Previous studies have shown that mutant sNASP could synergize with the Faslpr mutation in exacerbating autoimmunity and aggravating end-organ inflammation. In the current study, the sNASP mutation was introduced into Sle1.Yaa mice to detect whether it has a synergistic effect with Sle1 or Yaa loci. As expected, compared with Sle1.Yaa mice, Sle1.Yaa.ΔsNASP mice showed enlarged lymph nodes, aggravated renal inflammation, and shortened survival time. The proportions of CD3+ T cells, activated CD19+CD86+ B cells, Th1 cells in the spleen and lymph nodes, and Th17 cells in lymph nodes in Sle1.Yaa.ΔsNASP mice were increased compared to those in Sle1.Yaa mice. The levels of IFN-γ and TNF-α in the serum of Sle1.Yaa.ΔsNASP mice were higher than those of Sle1.Yaa mice. The above results show that mutant sNASP can interact with different lupus susceptibility genes and promote the disease process of systemic lupus erythematosus.