TLR4 and systemic lupus erythematosus: Interestingly, kringle-2 was found to be the locale of autoantibodies in the antiphospholipid syndrome in patients with Systemic Lupus Erythematosus (21) and was also found to act as a potential neuroinflammatory factor that stimulates microglial toll-like receptor 4 (TLR4) (22).