TNF and Respiratory tract infection: As significantly higher serum levels of TNF-α indicated more severe clinicopathological manifestations and three IgAN patients not involved in this research with the levels of TNF-α higher than 80 pg/mL suffered macroscopic hematuria only hours after respiratory tract infection, we supposed that a direct mucosa-kidney talk that was mediated at least in part by TNF-α may exist [27, 28].