Δ⁹Tetrahydrocannabinol attenuates Staphylococcal enterotoxin B‐induced inflammatory lung injury and prevents mortality in mice by modulation of miR‐17‐92 cluster and induction of T‐regulatory cells

Abstract

BACKGROUND AND PURPOSEStaphylococcal enterotoxin B (SEB) is a potent activator of Vβ8+T-cells resulting in the clonal expansion of ∼30% of the T-cell pool. Consequently, this leads to the release of inflammatory cytokines, toxic shock, and eventually death. In the current study, we investigated if Δ 9 tetrahydrocannabinol (THC), a cannabinoid known for its anti-inflammatory properties, could prevent SEB-induced mortality and alleviate symptoms of toxic shock. EXPERIMENTAL APPROACHWe investigated the efficacy of THC against the dual administration (intranasal and i.p.) of SEB into C3H/HeJ mice based on the measurement of SEB-mediated clinical parameters, including cytokine production, cellular infiltration, vascular leak, and airway resistance. In addition, the molecular mechanism of action was elucidated in vitro by the activation of splenocytes with SEB. KEY RESULTSExposure to SEB resulted in acute mortality, while THC treatment led to 100% survival of mice. SEB induced the miRNA-17-92 cluster, specifically miRNA-18a, which targeted Pten (phosphatase and tensin homologue), an inhibitor of the PI3K/Akt signalling pathway, thereby suppressing T-regulatory cells. In contrast, THC treatment inhibited the individual miRNAs in the cluster, reversing the effects of SEB. CONCLUSIONS AND IMPLICATIONSWe report, for the first time a role for the miRNA 17-92 cluster in SEB-mediated inflammation. Furthermore, our results suggest that THC is a potent anti-inflammatory compound that may serve as a novel therapeutic to suppress SEB-induced pulmonary inflammation by modulating critical miRNA involved in SEB-induced toxicity and death.

RNA-seq Analysis of δ9-Tetrahydrocannabinol-treated T Cells Reveals Altered Gene Expression Profiles That Regulate Immune Response and Cell Proliferation

“…To identify other genes whose expression might be regulated by THC, we used RNA-seq to compare the abundance in SEB-activated LN cells or CD4 ϩ T cells, with and without THC treatment. Some genes such as Il-4 identified in this study have already been shown in our previous studies and those of others (7,21). Interestingly, many genes such as Fpr2, which has been shown to have an anti-inflammatory role (26), but has never been shown previously to be induced by THC were also identified.…”

“…Suppression of miR-17/92 cluster by THC has been shown in another animal model (21). Indeed, the expression of precursor of this miRNA cluster was downregulated by THC in this study.…”

“…In the future, we will first validate the expression of these miRNAs in their mature miRNA form and then investigate their potential roles in the regulation of immune functions. Among those known miRNAs, the miR-17/92 cluster has been shown to be induced by SEB in an acute lung injury mouse model by regulating PIK3/Akt pathway (21). Because THC suppresses the expression of the miR-17/92 cluster in different tissues (21), it is likely that this effect is not cell type specific.…”

“…Among those known miRNAs, the miR-17/92 cluster has been shown to be induced by SEB in an acute lung injury mouse model by regulating PIK3/Akt pathway (21). Because THC suppresses the expression of the miR-17/92 cluster in different tissues (21), it is likely that this effect is not cell type specific. This miRNA cluster has been shown to have many functions and THC may exert a broad spectrum of functions through this miRNA cluster.…”

“…Previous studies from our laboratory demonstrated that THC can attenuate SEB-induced inflammation (7,21). However, to ensure that this model was working in the immune cells under current investigation, we used SEB to induce inflammation and tested the effect of THC.…”