Interactive Effect of Combined Intermittent and Sustained Hypoxia and High-Fat Diet on the Colonic Mucosal Microbiome and Host Gene Expression in Mice

Abstract

Saif Mashaqi,1,2 Daniel Laubitz,3 Efreim Joseph D Morales,3 Richard De Armond,1,2 Hanan Alameddin,4 Fayez K Ghishan,3 Pawel R Kiela,3,5 Sairam Parthasarathy1,2 1Department of Pulmonary, Allergy, Critical Care, and Sleep, University of Arizona College of Medicine, Tucson, AZ, USA; 2University of Arizona Health Sciences Center for Sleep & Circadian Sciences, University of Arizona College of Medicine, Tucson, AZ, USA; 3Department of Pediatrics, Steele Children’s Research Center, University of Arizona College of Medicine, Tucson, AZ, USA; 4The University of Arizona College of Pharmacy, Tucson, AZ, USA; 5Department of Immunobiology, University of Arizona College of Medicine, Tucson, AZ, USACorrespondence: Saif Mashaqi, Department of Pulmonary, Allergy, Critical Care, and Sleep Medicine, The University of Arizona, College of Medicine Tucson, 1625 N Campbell Ave, Tucson, AZ, 85719, USA, Tel [phone], Fax [phone], Email [email protected]: Gut dysbiosis can cause cardiometabolic disease. Gut dysbiosis can be independently caused by high-fat diet (HFD) and intermittent hypoxia (IH; characterizing obstructive sleep apnea), but the interactive effect of combined intermittent and sustained hypoxia (IH+SH) (characterizing obesity hypoventilation syndrome) and HFD on gut dysbiosis is unclear. We aimed to investigate the interactive effect of a combination of IH and SH and HFD on proximal colonic microbiota and colonic gene expression pattern.Methods: Male mice (n=16) were randomly received four different combinations of diet (normal versus HFD) and oxygen conditions (normoxia versus IH+SH) for 4 weeks. Bacterial DNA and mucosal epithelial cell RNA from proximal colon were collected for analysis of adherent microbiome and host’s gene expression analysis.Results: HFD during IH+SH (22.6 ± 5.73; SD) led to greater Firmicutes: Bacteroidetes ratio than HFD during normoxia (5.89 ± 1.19; p=0.029). HFD significantly decreased microbial diversity as compared to normal diet, but the addition of IH+SH to HFD mildly reversed such effects. When compared to HFD during normoxia, HFD with combination of IH+SH resulted in changes to host mucosal gene expression for apical junctional complexes and adhesion molecules. Specifically, when compared to HFD during normoxia, HFD during IH+SH led to upregulation of Claudin 2 and Syk (tight junction dysfunction and increased mucosal permeability), while the barrier promoting claudin 4 was downregulated.Conclusion: HFD during combined IH and SH causes greater gut dysbiosis and potentially adverse changes in colonic epithelial transcriptome than HFD during normoxia. The latter changes are suggestive of impaired gut barrier function.Keywords: hypoxia, microbiome, obesity, diet, gene expression, sleep apnea

Keywords

• hypoxia
• microbiome
• obesity
• diet
• gene expression
• sleep apnea