Young adult binge drinkers have immunophenotypic changes in peripheral polymorphonuclear cells and monocytes

Advances in identifying risk factors of metabolic dysfunction-associated alcohol-related liver disease

Metabolic dysfunction-associated alcohol-related liver disease (MetALD) is an emerging clinical entity that reflects the coexistence of metabolic dysfunction and alcohol-related liver injury. Unlike classical alcoholic liver disease (ALD), MetALD patients often present with lower to moderate alcohol consumption alongside metabolic risk factors such as obesity, insulin resistance, and dyslipidemia. These factors can synergistically worsen liver injury even at lower alcohol intake levels. Alcohol abuse remains a major global health concern, with the liver being the primary target of alcohol's toxic effects. Long-term alcohol exposure, especially when compounded by metabolic dysfunction, can accelerate the progression from steatosis to inflammation, fibrosis, cirrhosis, and hepatocellular carcinoma. Besides alcohol itself, various factors, including genetic predispositions, gender, type of alcoholic beverage, drinking patterns, and co-morbidities such as viral infections (HBV, HCV) modulate disease susceptibility and severity. This review summarizes current knowledge of risk factors contributing to MetALD, highlights the synergistic interactions between metabolic dysfunction and alcohol consumption, and discusses potential strategies for disease prevention and management.

Ethanol causes rapid decreases in the hepatic retinoid levels shaping the early steps of alcohol-associated liver disease

BACKGROUND

Chronic alcohol drinking causes hepatic vitamin A (retinoids and derivatives) decreases, which correlate with the progression and severity of alcohol-associated liver disease (ALD). However, the effects of short-term ethanol (EtOH) intake on liver retinoids and ALD are still undefined.

METHODS

Using high-performance liquid chromatography and high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC, HPLC-MS/MS), and molecular biology techniques in mice and cultured human hepatocytes, we investigated the temporal EtOH effects on retinoids and ALD.

RESULTS

In female and male mice, acute EtOH intake caused hepatic retinol (ROL) and retinyl palmitate (RP) decreases within hours, whereas it did not significantly change the retinoic acid (RA) levels, and those of the RA catabolism metabolite, 4-oxo-RA. After EtOH withdrawal, the liver recovered the ROL and RP levels within 48 h, whereas RA and 4-oxo-RA levels remained almost undetectable by this time point. Compared with control diet-fed mice, hepatic ROL and RP levels remained decreased in the 10-day and 3-week-long EtOH treatments, while retinyl oleate and linoleate increased. Interestingly, some of the RA signaling receptors, Rarβ, along with Cyp26a1, revealed dramatic transcript increases during the 10-day-long experiments that attenuated over time (up to 8 weeks), reflecting impaired RA signaling. Our work also showed that primary human hepatocytes serve as a model to better define the role of EtOH in retinoid biology.

CONCLUSIONS

This work reveals that acute and short-term exposures to EtOH disrupt retinoid homeostasis, identifying key events in the early pathogenesis of ALD.

Single-cell transcriptomics of peripheral blood mononuclear cells indicates impaired immune and inflammatory responses in alcohol-associated hepatitis

Alcohol-associated hepatitis (AH) is often diagnosed at advanced stages, and severe AH usually carries poor prognosis and high short-term mortality. In addition, it is challenging to understand the molecular mechanisms of immune dysregulation and inflammation in AH due to the cellular complexity and heterogeneity. Using single-cell RNA sequencing, previous studies found that AH causes dysfunctional innate immune response in monocytes, involving activation of pattern recognition receptors (PRRs) and cytokine signaling pathways. To better understand the coordinated systemic immune response in AH patients, we performed combined single-cell transcriptome, cell-surface protein, and lymphocyte antigen receptor analysis of peripheral blood mononuclear cell (PBMC) samples. Our results showed inflammatory cytokines and chemokines were highly expressed in AH, including IL-2, IL-32, CXC3R1 and CXCL16 in monocytes and NK cells, whereas HLA-DR genes were reduced in monocytes. In addition, we also found altered differentiation of T-helper cells (TH1 and TH17), which could further lead to neutrophil recruitment and macrophage activation. Lastly, our results also suggest impaired NK-cell activation and differentiation in AH with reduced gene expression of KLRC2 and increased gene expression of KLRG1. Our findings indicate different mechanisms may be involved in impaired immune and inflammatory responses for the cellular subtypes of the PBMCs in AH.

Young adult binge drinkers have immunophenotypical disarrangements in peripheral natural killer cells

Alcohol consumption is an issue of worldwide relevance and a problem of national scale in Mexico. The consumption pattern of large amounts of alcohol on the weekends is rapidly increasing in young adults between 18 and 29 years. Despite various studies that have focused on the noxious effect of alcohol in immunity, the changes in the immunoprofiles of peripheral blood cells have not been completely described. Natural killer cells (NKCs) are lymphoid-origin cells of the immune system that are responsible for defense against tumors, among other functions. In homeostatic conditions, they are found to be in a state of "dynamic balance" between activation and inhibition stimuli, which, if broken, may lead to immunosuppression or activation of cytotoxic mechanisms. In this study, we evaluated the immunoprofile of peripheral NKCs of 54 young adults, 29 of whom were binge drinkers and 25 of whom were low risk (LR), as classified by validated tools. Drinking habits were assessed. Blood samples were collected to perform hematic biometry and liver enzyme tests. Peripheral NKCs were identified by FACS, and stained for CCR2, CCR4, CCR5, CXCR4, CD69, CD127, CD137, TLR4, and Granzyme B. The data were analyzed using the t test and Mann-Whitney's U test for contrasts, and the effect size was obtained in order to evaluate the impact of each immunoprofile. The binge group showed increased expression of CCR5 and PD-1 in NKCs, respective to the LR group, and decreased expression of TLR4, along with fewer CCR4⁺ cells. Moreover, the increase found in CCR5 and PD-1 expression was correlated with the number of drinks in the last drinking session. Our findings show that young binge drinkers have different immunoprofiles that could suggest an early status of immunosuppression and trafficking of NKCs to the liver, which could be related to the onset of early liver damage, early in a subject's lifespan.