Acute Alcohol Exposure Exerts Anti-Inflammatory Effects by Inhibiting IκB Kinase Activity and p65 Phosphorylation in Human Monocytes

Abstract

Acute alcohol use is associated with impaired immune responses and decreased proinflammatory cytokine production. Our earlier studies have shown that acute alcohol intake inhibits NF-κB DNA binding in an IκBα-independent manner. We report using human peripheral blood monocytes and Chinese hamster ovary cells transfected with CD14 cells that acute alcohol treatment in vitro exerts NF-κB inhibition by disrupting phosphorylation of p65. Immunoprecipitation of p65 and IκBα revealed that acute alcohol exposure for 1 h decreased NF-κB-IκBα complexes in the cytoplasm. Phosphorylation of p65 at Ser536 is mediated by IκB kinase (IKK)β and is required for NF-κB-dependent cellular responses. We show that acute alcohol treatment decreased LPS-induced IKKα and IKKβ activity resulting in decreased phosphorylation of p65 at Ser536. Furthermore, nuclear expression of IKKα increased after alcohol treatment, which may contribute to inhibition of NF-κB. Decreased phosphorylation of nuclear p65 at Ser276 was likely not due to alcohol-induced inhibition of protein kinase A and mitogen- and stress-activated protein kinase-1 activity. Although decreased IκBα phosphorylation after acute alcohol treatment was attributable to reduced IKKβ activity, degradation of IκBα during alcohol exposure was IKKβ-independent. Alcohol-induced degradation of IκBα in the presence of a 26S proteasome inhibitor suggested proteasome-independent IκBα degradation. Collectively, our studies suggest that acute alcohol exposure modulates IκBα-independent NF-κB activity primarily by affecting phosphorylation of p65. These findings further implicate an important role for IKKβ in the acute effects of alcohol in immune cells.

Antigen-presenting cells under the influence of alcohol

“…Furthermore, acute alcohol exposure inhibits LPS-induced NFkB by decreasing DNA binding of the p65/ p50 heterodimer [20,40]. When IkB, an inhibitor of NFkB, was investigated, a specific decrease in phospho-specific IkBa was observed, indicating that alcohol interferes directly with NFkB activation and subsequently its regulation of other genes.…”

Ethanol Decreases Inflammatory Response in Human Lung Epithelial Cells by Inhibiting the Canonical NF-kB-Pathway

“…For example, alcohol was demonstrated to prevent LPS-induced nuclear translocation of p65 and p50 in human monocytes [46]. Also, acute exposure to alcohol for one hour resulted in decreased phosphorylation of p65 in human blood monocytes [47]. Regarding the specific NF-ĸB signaling, Mandrekar et al exposed human blood monocytes to 25 mM EtOH for one hour, as comparable to our setting, and found significantly elevated nuclear p50-levels matching decreased cytoplasmic p50-levels [19].…”

Molecular mechanisms of hepatic apoptosis regulated by nuclear factors

“…Chronic alcohol administration 239 primes hepatic macrophages and blood monocytes by sustained NF-κB240 activation and induction of LPS-stimulated TNFα[34]. However, acute 241 alcohol exposure decreased nuclear translocation and activation of the 242 NF-κB p65/p50 heterodimer[35]. NF-κB p50 homodimer binding to243 DNA was increased by acute alcohol in human monocytic cells.…”