CXCL8 and Parkinson disease: Markers of intestinal inflammation (calprotectin) and permeability (alpha-1-antitrypsin and zonulin) [41] as well as IL-1α, IL-1β, CXCL8 (interleukin 8), and C-reactive protein (CRP) [42] were found to be elevated in stool samples of PD patients compared to healthy controls.