However, currently available DPP-4 inhibitors have several adverse effects such as arthritis, pancreatitis, diarrhea, and congestive heart failure that limit their practical applications (Mascolo et al., 2016; Packer, 2018; Padron et al., 2020), and thus, new DPP-4 inhibitors are needed. Here, DPP4 is linked to Arthritis.