NOD2 and systemic lupus erythematosus: In conclusion, exposure to bacterial conserved molecular pattern may increase the expression of NOD2 in the monocytes of immunosuppressant naïve patients, which can subsequently lead to aberrant activation of PBMCs, resulting in the production of proinflammatory cytokines, implicating the innate immune response for extracellular pathogens in the immunopathological mechanisms in SLE.