Aldehyde Dehydrogenase 2 Mediates Alcohol-Induced Colorectal Cancer Immune Escape through Stabilizing PD-L1 Expression.

Despite the great success of immunotherapy in a small subset of cancer patients, most colorectal cancer (CRC) patients do not respond to programmed cell death receptor 1 (PD-1) blockade immunotherapy. There is an urgent medical need to elucidate how cancer cells evade immune response and to develop novel means to boost the efficacy of immune checkpoint inhibitors. In this study, alcohol induces ligand programmed cell death receptor 1 (PD-L1) expression of CRC cells in vitro and in vivo. Alcohol exposure is shown to induce aldehyde dehydrogenase 2 (ALDH2) expression that is a crucial enzyme involved in alcohol metabolism, and low level of lymphocytes infiltration in the murine CRC model and patients. Intriguingly, ALDH2 and PD-L1 protein expression are positively correlated in tumor tissues from the CRC patients. Mechanistically, ALDH2 stabilizes PD-L1 protein expression by physically interacting with the intracellular segment of PD-L1 and inhibiting its proteasome-dependent degradation mediated by an E3 ubiquitin ligase Speckle Type POZ Protein (SPOP). Importantly, inhibition of ALDH2 reduces PD-L1 protein in CRC cells and promotes tumor-infiltrating T cells (TILs) infiltration, presumably leading to the significant potentiation of anti-PD-1 antibody efficacy in a mouse CT26 CRC model. The findings highlight a crucial role played by ALDH2 to facilitate alcohol-mediated tumor escape from immunity surveillance and promote tumor progression.

Effect of Tongxieyaofang decoction on colonic mucosal protein expression profiles in rats with visceral hypersensitivity.

OBJECTIVE: To explore the underlying mechanism of action of Tongxieyaofang decoction in rats with visceral hypersensitivity using proteomics technology. METHODS: Twenty-four female Sprague-Dawley rats were randomly divided into three groups: control group, irritable bowel syndrome (IBS) group and Tongxieyaofang treatment group. An IBS model, characterized as visceral hypersensitivity, was established using the odour of mothballs as conditional stimulation and colorectal distension combined with classic physical restraint as non-conditional stimulation. Rats were intragastrically treated with Tongxieyaofang (2 or 4 mL·kg－1·d－1) for 4 weeks. On the 45th day, the rats were dissected and the colonic mucosal proteins were extracted. Differential protein spots were screened by fluorescent two-dimensional differential gel electrophoresis (2D-DIGE), and identified by matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI-TOF-MS). Western blotting experiments were performed to verify the changes observed in 2D-DIGE and MALDI-TOF-MS. RESULTS: It was found that the visceral sensitivity of rats in the Tongxieyaofang treatment group (4 mL/kg) was lower than that in the IBS group (P < 0.01). Sixty-one protein spots were differentially expressed between the IBS group and the Tongxieyaofang treatment group. Of these, 23 spots were upregulated in the Tongxieyaofang treatment group, while 38 spots were downregulated. Three specific proteins were successfully identified from the five protein spots with the most obvious changes. The two upregulated proteins were transgelin (TAGLN) and acetaldehyde dehydrogenase 2 (Aldh2) and the downregulated protein was cytokeratin 8 (CK8). CONCLUSION: Tongxieyaofang can dose-dependently ameliorate visceral hypersensitivity in rats and the mechanism of action may involve the upregulation of TAGLN and Aldh2 and the downregulation of CK8.

Hepatic injury and inflammation alter ethanol metabolism and drinking behavior.

While liver injury is commonly associated with excessive alcohol consumption, how liver injury affects alcohol metabolism and drinking preference remains unclear. To answer these questions, we measured the expression and activity of alcohol dehydrogenase 1 (ADH1) and acetaldehyde dehydrogenase 2 (ALDH2) enzymes, ethanol and acetaldehyde levels in vivo, and binge-like and preferential drinking behaviors with drinking in the dark and two-bottle choice in animal models with liver injury. Acute and chronic carbon tetrachloride (CCl4), and acute LPS-induced liver injury repressed hepatic ALDH2 activity and expression and consequently, blood and liver acetaldehyde concentrations were increased in these models. In addition, chronic CCl4 and acute LPS treatment inhibited hepatic ADH1 expression and activity, leading to increases in blood and liver ethanol concentrations. Consistent with the increase in acetaldehyde levels, alcohol drinking behaviors were reduced in mice with acute or chronic liver injury. Furthermore, oxidative stress induced by hydrogen peroxide attenuated ADH1 and ALDH2 activity post-transcriptionally, while proinflammatory cytokines led to transcriptional repression of ADH1 and ALDH2 in cultured hepatocytes, which correlated with the repression of transcription factor HNF4α. Collectively, our data suggest that alcohol metabolism is suppressed by inflammation and oxidative stress, which is correlated with decreased drinking behavior.

Autoantibody against aldehyde dehydrogenase 2 could be a biomarker to monitor progression of Graves' orbitopathy.

PURPOSE: This study surveyed the novel autoantigens expressed in the orbital fat tissue of patients with Graves' orbitopathy (GO) and explored the possibility of the autoantibodies against novel autoantigens as biomarkers for GO. METHODS: We used immuno-proteomic methods to survey novel autoantigens expressed in the orbit fat tissue of GO patients and confirmed by enzyme-linked immunosorbent assay (ELISA). RESULTS: One protein spot (aldehyde dehydrogenase 2 (ALDH2)) revealed high reactivity with the GO serum than did the healthy control serum and was further verified by ELISA. We found that the plasma anti-ALDH2 antibody level was increased in GO patients compared to healthy control donors. In addition, anti-ALDH2 antibody level was correlated with GO activity classified by clinical activity score(r = 0.588, p < 0.001, using Pearson's correlation). CONCLUSIONS: These increased levels of anti-ALDH2 antibody in GO serum suggested that ALDH2 could attribute target autoantigen in GO, and anti-ALDH2 autoantibody might serve as a biomarker for GO and help to predict disease activity.

Proteomic analysis of human nasal mucosa: different expression profile in rhino-pathologic states.

BACKGROUND: Rhinitis comprises several diseases with varying causes and different clinical manifestations and pathological features, but treated as a single clinical disorder. As heterogeneous disease, proper differential diagnosis is useful to delineate appropriate therapeutic intervention. Comparative proteomic investigation was aimed to provide information for specific differentially expressed proteins in rhino pathologic state, that could be used for diagnostic purpose and therapeutic monitoring. METHODS: Proteins extracted from nasal mucosa cells of patients with different features of rhinitis and from control subjects, were separated by 2-DE. Proteins differentially expressed were identified by mass spectrometry (MS). RESULTS: Comparative proteomic analyses led to the identification of eighteen proteins differentially expressed in patients with rhinitis, mainly related to cell defense and innate and acquired immunity. From that, at least one protein can be a possible candidate as biomarker of disease.