Protease-activated receptor-2 (PAR-2) activation has been implicated in the potent allergenicity elicited by cockroaches and contributes substantially to inflammatory and metabolic dysfunction [38], and PAR-2 antagonists inhibit diet-induced obesity, reverse IR, and glucose intolerance, and they beneficially modulate liver and pancreatic metabolic parameters [39]. This evidence concerns the gene F2RL1 and obesity due to melanocortin 4 receptor deficiency.