GDF15 and obesity due to melanocortin 4 receptor deficiency: Concerning Timp1, a shed protein implicated in the inflammatory response plays a central regulatory role at the crossroads of protein–protein interactions between obesity-related proteins and feeding behavior-related proteins (Gdf15, Cd44, Sparc, and Angptl4) as well as axon guidance-related proteins (Ctsb, Hspg2, Col1a1, and 2) and neuroinflammation-related proteins (Cx3cl1, Anxa1, and Mif).