The role of bacterial biofilm components in anti-DNA induction in SLE - Summary Systemic lupus erythematosus (SLE) is a complex autoimmune disease marked by the production of antibodies against DNA and other nuclear molecules (ANAs), which are associated with tissue damage. These antibodies target both DNA and RNA-protein complexes, with genetic and environmental factors (like infections) playing a role in triggering the disease. Gut dysbiosis, characterized by harmful bacteria overgrowth or reduced bacterial diversity, is also linked to lupus pathogenesis. SLE diagnostics commonly focus on antibodies to double-stranded (B-form) DNA. However, recent research has shown that SLE patients can also develop antibodies that bind to Z-DNA, a rare, left-handed DNA structure typically immunogenic in animal models. The study suggests that foreign DNA, such as from bacterial biofilms, could play a role in driving the production of anti-DNA antibodies. Biofilms, made of amyloids, polysaccharides, and extracellular DNA (eDNA), may contain Z-DNA, potentially offering a unique environment for immune system activation. Our preliminary studies using E. coli and Salmonella biofilms found that amyloid curli/DNA complexes can stimulate antibodies to DNA, including against Z-DNA, as well as other autoantibodies. Furthermore, a high-cholesterol diet, which increases the formation of STm biofilms in the intestinal tract, leads to higher levels of anti-dsDNA antibody levels at early timepoints post-infection. It is well established that high-cholesterol diets can reduce the expression of tight junction proteins like occludin and claudins, leading to increased permeability. The primary objective of the proposed project is to elucidate the mechanisms by which DNA in biofilms, whether present in the gut due to dysbiosis or due to infection with enteric organisms, can induce anti-DNA antibody production. The central hypothesis is that a high-cholesterol diet increases biofilm and curli/DNA load in the gut. At the same time, it compromises gut barrier integrity, allowing greater translocation of bacteria and curli into systemic compartments, thereby stimulating cytokines that amplify the production of anti-DNA and other autoantibodies whose properties depend on host immune disturbances. We will test our hypothesis by pursuing the following specific aims. In aim1, we will determine the contribution of a high-cholesterol diet to biofilm-mediated autoimmunity. In aim2, we will characterize the fine specificity, immunochemical properties, and functional activity of anti-DNA antibodies induced by infection or curli/DNA administration identify the immune pathways responsible for the generation of autoantibodies in response to biofilms. In aim 3, we will identify the immune pathways responsible for the generation of autoantibodies in response to biofilms.
