Upregulation of inflammatory genes and pathways links obesity to severe COVID-19

Obesity is a risk factor for developing severe COVID-19. However, the mechanism underlying obesity-accelerated COVID-19 remains unclear. Here, we report results from a study in which K18-hACE2 mice were fed an obesity-inducing western diet (WD) for over 3 months before intranasal infection with SARS-CoV2. After infection, the WD-fed K18-hACE2 mice lost more body weight and had more severe lung inflammation than normal chow (NC)-fed mice. Bulk RNAseq analysis of lungs and adipose tissue revealed that a diverse landscape of various immune cells, inflammatory markers, and pathways are upregulated in obese COVID-19 patients or the WD-fed K18-hACE2 mice when compared with their respective control groups. When compared with infected NC-fed mice in the lung, the infected WD-fed mice had upregulation of IL-6, a well-established marker for severe COVID-19. These results indicate that obesity-accelerated severe COVID-19 caused by SARS-CoV-2 infection in the K18-hACE2 mouse model can be used for dissecting the cellular and molecular mechanisms underlying pathogenesis. Furthermore, in the transcriptome analysis of the lung and adipose tissue obtained from deceased COVID-19 patients, we found upregulation of an array of genes and pathways associated with Inflammation. Both the K18-hACE2 mouse model and human COVID-19 patient data support a link between inflammation and an obesity-accelerated COVID-19 disease phenotype. Comparitive gene expression analysis was done using bulk RNA-seq data comparing NC (normal chow) and WD (western diet to induce obesity) fed K18-hACE2 mice (adipose tissue and lung tissue) infected with SARS-CoV-2 (WA).