BET Protein Inhibition Regulates Macrophage Chromatin Accessibility and Microbiota-Dependent Colitis

Introduction

In colitis, macrophage functionality is altered compared to normal homeostatic conditions. Loss of IL-10 signaling results in an inappropriate chronic inflammatory response to bacterial stimulation. It remains unknown if inhibition of bromodomain and extra-terminal domain (BET) proteins alters usage of DNA regulatory elements responsible for driving inflammatory gene expression. We determined if the BET inhibitor, (+)-JQ1, could suppress inflammatory activation of macrophages in Il10^-/- mice.

Methods

We performed ATAC-seq and RNA-seq on Il10^-/- bone marrow-derived macrophages (BMDMs) cultured in the presence and absence of lipopolysaccharide (LPS) with and without treatment with (+)-JQ1 and evaluated changes in chromatin accessibility and gene expression. Germ-free Il10^-/- mice were treated with (+)-JQ1, colonized with fecal slurries and underwent histological and molecular evaluation 14-days post colonization.

Results

Treatment with (+)-JQ1 suppressed LPS-induced changes in chromatin at distal regulatory elements associated with inflammatory genes, particularly in regions that contain motifs for AP-1 and IRF transcription factors. This resulted in attenuation of inflammatory gene expression. Treatment with (+)-JQ1 in vivo resulted in a mild reduction in colitis severity as compared with vehicle-treated mice.

Conclusion

We identified the mechanism of action associated with a new class of compounds that may mitigate aberrant macrophage responses to bacteria in colitis.

Public health crisis in the refugee community: little change in social determinants of health preserve health disparities

Structural inequities and lack of resources put vulnerable refugee communities at great risk. Refugees flee their country of origin to escape persecution and flee from war, famine and torture. Resettled refugee communities become particularly vulnerable during times of crisis due to limited English proficiency and poor social determinants of health (SDOH), which create barriers to attaining and sustaining health and wellbeing for themselves and their families. The purpose of this case study was to evaluate SDOH among a refugee community in the Southeastern United States. We surveyed the community twice during a 1-year period to assess various elements of SDOH. Among a primarily African and Southeast Asian refugee community, 76% reported difficulty paying for food, housing and healthcare during the first round of surveys. During the second round of surveys at the beginning of the Coronavirus pandemic, 70% reported lost income; 58% indicated concern about paying bills. There was little change during the 12-month study period, showing that SDOH are an enduring measure of poor health and wellbeing for this vulnerable refugee community.