JAK2 and obesity due to melanocortin 4 receptor deficiency: This may be at least one molecular mechanism involved in the reduced B cell function in individuals with obesity, as it induces the secretion of pro-inflammatory cytokines (IL-6/TNF-α) in human peripheral blood B cells through activation of JAK2/STAT3 and p38MAPK/ERK1/2 signaling pathways [61, 62].