Effects of a high cholesterol diet on the pathogenesis of influenza A virus infection in mature mice

Influenza is one of the most prevalent and devastating infectious diseases in the world. But how host factors may function to increase disease susceptibility or severity has not been fully elucidated. Here, we examined the effects of a high cholesterol diet in modulating the immune response to influenza A virus (IAV) infection in mice. Six-week-old C57BL/6J mice were fed either a standard rodent chow or a matched diet containing 2% cholesterol throughout the experiment. After five weeks of feeding, mice were inoculated with mouse-adapted human IAV (Puerto Rico/8/1934) and tissues were collected at days 0, 4, 8, and 16 post-infection (p.i.). Weights and food disappearance were recorded daily and sickness behavior was evaluated by a burrowing behavior test. Circulating free cholesterol and triglycerides were measured at each time point and diet-induced changes to liver appearance were evaluated at day 16 p.i. Diet-induced changes to T and B cell peripheral responses were assessed, respectively, by measuring MHC Class I-restricted antigen recall responses in the spleen and virus-specific neutralizing antibody levels in the blood. Bulk RNA sequencing was performed on the lungs to evaluate the effect of diet on the lung transcriptome during infection. Diet-induced changes to immune cell populations were determined by flow cytometry. Finally, a crossover design experiment was used to evaluate the effects of diet reversal on IAV-induced morbidity. Cholesterol-fed mice exhibited greater disease morbidity compared to controls fed a normal diet. Dietary cholesterol did not affect the ability to generate an adaptive immune response but rather enhanced it. Cholesterol-fed mice exhibited increased total circulating cholesterol prior to infection and decreased triglycerides after infection as well as altered liver appearance. Gene ontology analysis revealed upregulation of viral-response pathways and leukocyte trafficking to the lungs of mice fed a high cholesterol diet, which coincided with increased number of polyfunctional T cells, CD11bhi DCs, Ly6Chi CD11bhi monocytes and granulocytes, and alveolar macrophages. Taken together, these data indicate that dietary cholesterol may induce a heightened immune response to IAV infection that results in greater morbidity in mature mice.LimitedAuthor requested closed access (OA after 2yrs) in Vireo ETD syste