TNF and diabetes mellitus: Topical application of propolis improved the wound healing process of a streptozotocin (STZ)-induced wound in a type I diabetes mellitus (DM) mouse model, which was attributed to a decrease in pro-inflammatory cytokines such as IL-6, IL-1B, and TNF-α, as well as an increase in collagen formation via the transforming growth factor-1 (Smad2 and Smad3) signaling pathways (35).