TNF and liver dysplastic nodule: In terms of the role of M2 macrophages in the pathogenesis of DN, at the early stage of infection or injury of diabetic kidney, monocytes differentiate into M1 macrophages to secrete inflammatory cytokines (e.g., IL-1β and TNF-α) and express receptors that are needed for antigen presentation (e.g., MHC II) and pathogen recognition (e.g., TLRs) (Landis et al., 2018).