Endogenous cannabinoid, anandamide mitigates acute lung injury by altering the microbiome and metabolome profile in the gut-lung axis with the induction of an anti-inflammatory response

Abstract

Abstract Staphylococcus Enterotoxin B (SEB) is a superantigen that can activate ~30% of T cells. Inhalation of SEB can lead to toxic shock syndrome and death. We have shown that anandamide (AEA) is effective in ameliorating SEB-induced ALI. Cross-talk between microbiome through the gut-lung axis (GLA) can influence the immune and respiratory functions. In the current study, we found that AEA treatment alleviated SEB-induced ALI in mice by alteration in the microbiome and the metabolome profile especially short-chain fatty acid (SCFA) production in the GLA. Sequencing of the V3–V4 region of 16S rRNA of colon, cecal flushes and lungs was performed and analysis showed that AEA treatment led to a significant increase, starting from the phylum level in Bacteroidetes until genus Aldercreutzia. Mass Spectrometric (MS) analysis revealed that there was a significant increase in the SCFAs in AEA treatment group, especially iso-butyrate, which may be responsible for induction of T regulatory cells (T regs). Flow cytometry data showed that AEA increased CD4+FOXP3+ in the lung compared to vehicle-treated SEB-induced disease group. Our study also showed that AEA treatment significantly decreased the infiltration of inflammatory cells in the lungs. Furthermore, AEA treatment led to a significant decrease in gut and lung leakage, and pro-inflammatory cytokines (IL-2 and TNFα) while increasing anti-inflammatory cytokines (IL-10). Collectively, these data suggest that AEA ameliorates ALI and prevents leakage through modulation of microbiome profile and the metabolome in the GLA while promoting an anti-inflammatory response to include induction of Tregs and decrease in pro-inflammatory cytokines.