Systemic lupus erythematosus (SLE) is a multifaceted autoimmune disease driven by immune dysregulation. This study investigated the relationship between gut microbiota and lupus severity using the MRL/lpr lupus mouse model. Mice were grouped based on total immunoglobulin (Ig)G, IgG2a levels, and urine albumin-to-creatinine ratio (ACR), allowing for the comparison of gut microbiota profiles across different disease severities. Interestingly, severe lupus mice exhibited significant reductions in