TLR2 and systemic lupus erythematosus: However, an overproduction of probiotic metabolites like peptidoglycan fragments or bacterial DNA can hyperactivate DCs via TLR2/9 or NOD2, boosting BAFF/APRIL production via NF-κB/MAPK pathways, potentially triggering systemic autoreactive B cells and exacerbating SLE autoimmunity (139–141).