Alcohol-induced miR-27a regulates differentiation and M2 macrophage polarization of normal human monocytes.

Alcohol abuse is a leading cause of liver disease characterized by liver inflammation, fatty liver, alcoholic hepatitis, or liver cirrhosis. Immunomodulatory effects of alcohol on monocytes and macrophages contribute to alcoholic liver disease. Alcohol use, an independent risk factor for progression of hepatitis C virus (HCV) infection-mediated liver disease, impairs host defense and alters cytokine production and monocyte/macrophage activation. We hypothesized that alcohol and HCV have synergistic effects on the phenotype and function of monocytes. Our data show that acute alcohol binge drinking in healthy volunteers results in increased frequency of CD16(+) and CD68(+) and M2-type (CD206(+), dendritic cell [DC]-SIGN(+)-expressing and IL-10-secreting) circulating CD14(+) monocytes. Expression of HCV-induced CD68 and M2 markers (CD206 and DC-SIGN) in normal monocytes was further enhanced in the presence of alcohol. The levels of microRNA (miR)-27a was significantly upregulated in monocytes cultured in the presence of alcohol or alcohol and HCV as compared with HCV alone. The functional role of miR-27a in macrophage polarization was demonstrated by transfecting monocytes with an miR-27a inhibitor that resulted in reduced alcohol- and HCV- mediated monocyte activation (CD14 and CD68 expression), polarization (CD206 and DC-SIGN expression), and IL-10 secretion. Overexpression of miR-27a in monocytes enhanced IL-10 secretion via activation of the ERK signaling pathway. We found that miR-27a promoted ERK phosphorylation by downregulating the expression of ERK inhibitor sprouty2 in monocytes. Thus, we identified that sprouty2 is a target of miR-27a in human monocytes. In summary, our study demonstrates the regulatory role of miR-27a in alcohol-induced monocyte activation and polarization.

Aflatoxins B(1), B(2) and G(1) modulate cytokine secretion and cell surface marker expression in J774A.1 murine macrophages.

Aflatoxins are fungal products which occur in food and feed. They are potent hepatocarcinogens, and are known to cause immunosuppression. We investigated the effect of aflatoxin B(1) (AFB(1)), aflatoxin B(2) (AFB(2)) and aflatoxin G(1) (AFG(1)) exposure, alone and in combination, on the secretion of key pro- and anti-inflammatory cytokines from the murine macrophage cell line, J774A.1. Exposure of macrophages to low doses of aflatoxin (0.01 or 0.1ng/mL) resulted in a statistically significant change in the secretion of a number of cytokines following stimulation with lipopolysaccharide (LPS), a component of Gram-negative bacterial cell walls. Specifically, treatment with AFB(1) or AFB(2) alone significantly decreased (P<0.01) the secretion of the anti-inflammatory cytokine interleukin (IL) 10 (IL-10), while the secretion of the pro-inflammatory cytokine IL-6 was significantly increased (P<0.01). In addition, aflatoxin exposure affected expression levels of key cell surface markers involved in the inflammatory response. Toll-like receptor 2 (TLR2) and Cluster of Differentiation 14 (CD14) expression levels decreased significantly (P<0.01), but Toll-like receptor 4 (TLR4) expression was unaffected. This data provides further insight into the mechanisms by which aflatoxins modulate the host immune response to exert their immunosuppressive activity.

Gemtuzumab ozogamicin (Mylotarg) upregulates tissue factor expression but not secretion of inflammatory cytokines TNF-alpha or IL-8.

Gemtuzumab ozogamicin (GO; Mylotarg (R)) is an antibody-targeted chemotherapeutic agent approved for the treatment of CD33+ acute myelogenous leukemia (AML). GO is more commonly associated with the development of Sinusoidal Obstructive Syndrome (SOS) than any other chemotherapeutic agent in this patient group. Previous investigations have shown that SOS is a pro-coagulant and pro-inflammatory syndrome. Treatment of THP1 cells (CD33+ AML cell line) with GO alone, or in combination with unconjugated CD33 antibody (hP67.6), resulted in a statistically significant (P<0.01) increase in tissue factor (TF) expression, but HepG2 cells (CD33 hepatocyte cell line) were unaffected. Cytokine secretion was not affected by GO treatment in either cell line. These results indicate that GO exerts a pro-coagulant response in certain cell types, which may predispose individuals to developing SOS.