Differential expression and functional role of cannabinoid genes in alcohol users

Abstract

Background Genetic factors account for about fifty percent of the risk for alcoholism and alcohol dependence (AD) has been reported to be influenced by cannabinoid receptors (CBRs) and the endocannabinoid system (ECS). Previous studies have focused on cannabinoids and alcohol-related effects in the CNS; however, the role CBRs play on alcohol effects in the immune system has not been elucidated yet. Since alcohol can affect immune responses and have detrimental effects on immune cells such as dendritic cells (DCs), we hypothesize that alcohol can exert its effects on DCs by modulating changes in CBRs, which in turn can regulate important DC functions such as cytokine production. Methods Therefore, we studied the expression of CNR1 and CNR2, and the novel cannabinoid G protein-coupled receptor (GPCR) 55 (GPR55) in human monocyte-derived dendritic cells (MDDCs) from alcohol users. CNR1, CNR2, and GPR55 genes were measured by qRT-PCR and protein by flow cytometry. MDDCs from alcohol users show significantly higher levels of CNR2 and GPR55 compared to MDDCs from non-users. These findings were further confirmed using MDDCs treated with alcohol. Inflammatory cytokines were measured in EtOH-treated and non-treated cells by antibody array. Results Functional effects of CBRs on MDDCs were shown by CB2 and GPR55 siRNA transfection. Transfected EtOH-treated cells showed significantly higher levels of proinflammatory cytokine production as measured by IL-1β expression. Our results provide insights into alcohol mechanisms of DC regulation and show, for the first time, that alcohol is inducing CNR2 and GPR55 in human DCs.

Alcohol Versus Cannabinoids: A Review of their Opposite Neuro-Immunomodulatory Effects and Future Therapeutic Potentials

“…Interestingly, our previous findings suggest that CB 2 and GPR55 are highly up regulated in alcohol abusers and these receptors also play a crucial immune-regulatory role during alcohol treatment in vitro [33]. Furthermore, our own study highlighted in this review confirms that cannabinoids and alcohol exert differential and opposite inflammatory effects as shown by the cytokine array profiles performed with monocyte-derived dendritic cells from alcohol, marijuana, and control donors (Figures 1 and 2).…”

“…Whole cell lysates (WCL) were extracted from dendritic cells derived from monocytes obtained from blood donors as previously described by us [33]. Ray Biotech inflammation arrays (catalog # AAHINF-3-8, Ray Biotech, Norcross, GA) were incubated with (WCL) from healthy control, alcohol abuser, and marijuana smoker.…”

“…Moreover, acute and chronic alcohol differentially modulate monocyte/macrophage activation and cytokine production [47]. Our recent publication using human Monocyte-Derived Dendritic Cells (MDDC) supports an increase of pro-inflammatory cytokine production after 0.1 % ethanol treatment in vitro [33] compare to untreated cells. Moreover, protein array profiles (Figure 2) of MDDC derived from alcohol user revealed a significant increase in the production of several pro-inflammatory cytokines and chemokines (MCP-1, ICAM-1, IL-16, GM-CSF, IL-10, IL-309, TNF-α, TIMP-2, MCSF, PDGF-β, MIP-1α, IL-12-p40, IL-15).…”

Epigenetic Interactions between Alcohol and Cannabinergic Effects: Focus on Histone Modification and DNA Methylation

“…Additionally, previous reports from our laboratory showed increased expression of cannabinoid receptors CB 2 and GPR55 in MDDCs from alcohol users, which was further validated in-vitro in primary human MDDCs treated with alcohol [94]. All of these provide support for the existence of a connection between endocannabinergic signaling pathways and alcohol abuse.…”

Molecular mechanisms of ethanol-associated oro-esophageal squamous cell carcinoma

“…GPR 55 was overexpressed in monocyte-derived dendritic cells from alcohol users or those treated with ethanol [169]. The ability of ethanol to increase gamma-aminobutyric acid release can be regulated by different GPCRs, such as cannabinoid-1 receptor, corticotropin-releasing factor 1 receptor and 5-hydroxytryptamine 2C receptor [170].…”