Cholesterol Enhances Helicobacter pylori Resistance to Antibiotics and LL-37

Abstract

ABSTRACTThe human gastric pathogenHelicobacter pyloristeals host cholesterol, modifies it by glycosylation, and incorporates the glycosylated cholesterol onto its surface via a cholesterol glucosyltransferase, encoded bycgt. The impact of cholesterol onH. pyloriantimicrobial resistance is unknown.H. pyloristrain 26695 was cultured in Ham's F12 chemically defined medium in the presence or absence of cholesterol. The two cultures were subjected to overnight incubations with serial 2-fold dilutions of 12 antibiotics, six antifungals, and seven antimicrobial peptides (including LL-37 cathelicidin and human alpha and beta defensins). Of 25 agents tested, cholesterol-grownH. pyloricells were substantially more resistant (over 100-fold) to nine agents than wereH. pyloricells grown without cholesterol. These nine agents included eight antibiotics and LL-37.H. pyloriwas susceptible to the antifungal drug pimaricin regardless of cholesterol presence in the culture medium. Acgtmutant retained cholesterol-dependent resistance to most antimicrobials but displayed increased susceptibility to colistin, suggesting an involvement of lipid A. Mutation oflpxE, encoding lipid A1-phosphatase, led to loss of cholesterol-dependent resistance to polymyxin B and colistin but not other antimicrobials tested. Thecgtmutant was severely attenuated in gerbils, indicating that glycosylation is essentialin vivo. These findings suggest that cholesterol plays a vital role in virulence and contributes to the intrinsic antibiotic resistance ofH. pylori.