TNF and infection: It has been reported that, after infection with G. parasuis, the expression of p38, ERK, and JNK increased in porcine alveolar macrophages (PAMs) via the NF-κB and MAPK signaling pathways, leading to the upregulation of inflammatory cytokines such as IL-1α, IL-1β, IL-6, IL-8, and TNF-α [33].