BPIFB1 and obesity due to melanocortin 4 receptor deficiency: In contrast, proteins related to the immune system, such as those associated with the antimicrobial humoral response and response to other organism (such as BPI fold-containing family B member 1 and 2, Secretory leucocyte peptidase inhibitor, Mucin-7, Histatin-3, and Statherin) were down-regulated in individuals with obesity (Figure 5).