Bacterial genes involved in LPS biosynthesis were increased in mucosal and fecal samples from PD patients compared with those in non-PD patients, and serum lipopolysaccharide-binding protein (LBP) levels in PD patients were lower than those of controls when the integrity of the intestinal mucosa was not compromised (Hasegawa et al., 2015). Here, LBP is linked to Parkinson disease.