ABCC1 deficiency potentiated noise-induced hearing loss in mice by impairing cochlear antioxidant capacity.

The ABCC1 gene belongs to the ATP-binding cassette membrane transporter superfamily, which plays a crucial role in the efflux of various endogenous and exogenous substances. Mutations in ABCC1 can result in autosomal dominant hearing loss. However, the specific roles of ABCC1 in auditory function are not fully understood. Through immunofluorescence, we found that ABCC1 was expressed in microvascular endothelial cells (ECs) of the stria vascularis (StV) in the murine cochlea. Then, an Abcc1 knockout mouse model was established by using CRISPR/Cas9 technology to elucidate the role of ABCC1 in the inner ear. The ABR threshold did not significantly differ between WT and Abcc1-/- mice at any age studied. After noise exposure, the ABR thresholds of the WT and Abcc1-/- mice were significantly elevated. Interestingly, after 14 days of noise exposure, ABR thresholds largely returned to pre-exposure levels in WT mice but not in Abcc1-/- mice. Our subsequent experiments showed that microvascular integrity in the StV was compromised and that the number of outer hair cells and the number of ribbons were significantly decreased in the cochleae of Abcc1-/- mice post-exposure. Besides, the production of ROS and the accumulation of 4-HNE significantly increased. Furthermore, StV microvascular ECs were cultured to elucidate the role of ABCC1 in these cells under glucose oxidase challenge. Notably, 30 U/L glucose oxidase (GO) induced severe oxidative stress damage in Abcc1-/- cells. Compared with WT cells, the ROS and 4-HNE levels and the apoptotic rate were significantly elevated in Abcc1-/- cells. In addition, the reduced GSH/GSSG ratio was significantly decreased in Abcc1-/- cells after GO treatment. Taken together, Abcc1-/- mice are more susceptible to noise-induced hearing loss, possibly because ABCC1 knockdown compromises the GSH antioxidant system of StV ECs. The exogenous antioxidant N-acetylcysteine (NAC) may protect against oxidative damage in Abcc1-/- murine cochleae and ECs.

Susceptibility of immature spiral ganglion neurons to aminoglycoside-induced ototoxicity is mediated by the TRPV1 channel in mice.

Aminoglycoside antibiotics are among the most common agents that can cause sensorineural hearing loss. From clinical experience, premature babies, whose inner ear is still developing, are more susceptible to aminoglycoside-induced ototoxicity, which is echoed by our previous study carried out in organotypic cultures. This study aimed to investigate whether a nonselective cation channel, TRPV1, contributes to the susceptibility of immature spiral ganglion neurons (SGNs) to the damage caused by aminoglycosides. Through western blotting and immunofluorescence, we found that the TRPV1 expression levels were much higher in immature SGNs than in their mature counterparts. In postnatal day 7 cochlear organotypic cultures, AMG-517 reduced reactive oxygen species generation and inhibited SGN apoptosis under aminoglycoside challenge. However, in adult mice, AMG-517 did not ameliorate the ABR threshold increase at high frequencies (16 kHz and 32 kHz) after aminoglycoside administration, and the SGNs within the cochleae had no morphological changes. By further regulating the function of TRPV1 in primary cultured SGNs with its inhibitor AMG-517 and agonist capsaicin, we demonstrated that TRPV1 is a major channel for aminoglycoside uptake: AMG-517 can significantly reduce, while capsaicin can significantly increase, the uptake of GTTR. In addition, TRPV1 knockdown in SGNs can also significantly reduce the uptake of GTTR. Taken together, our results demonstrated that aminoglycosides can directly enter immature SGNs through the TRPV1 channel. High expression of TRPV1 contributes to the susceptibility of immature SGNs to aminoglycoside-induced damage. The TRPV1 inhibitor AMG-517 has the potential to be a therapeutic agent for preventing aminoglycoside-induced ototoxicity in immature SGNs.

SIRT1 Asn346 sugar chain promoting collagen deacetylation protective effect on osteoblasts under stress.

Silencing type information regulator homolog 1 (SIRT1) is a class of nicotinamide adenine dinucleotide (NAD+) dependent deacetylases, which is the convergence point of important physiological processes in vivo, namely, osteoblast aging, energy metabolism, and bone remodeling. To verify whether the O-acetylglucosamine (O-GlcNAc) modification of SIRT1 in the nucleus of osteoblasts enhances its deacetylase activity under stress and protects osteoblasts through the RANK/RANKL signaling pathway by collagen deacetylation. The R language and online data research identified SIRT1 as being involved in bone metabolism. Enrichment analysis showed that SIRT1 is involved in osteoblast transcription, apoptosis, and deacetylation pathways. Interactive Immuno-blotting and immunofluorescence experiments revealed that SIRT1 and O-glycosylation catalytic enzyme (OGT) were localized in the nucleus. Mass Spectrometry analysis showed that O-glycosylation occurred on the asparagine at the 346th position of SIRT1, and N346th was located in the central domain of SIRT1. Furthermore, the protein structure analysis of PyMol also proved that the OGT binding region was in the central domain of SIRT1. Under physiological conditions, both wtSIRT1 and SIRT1N346R can inhibit RANKL-mediated transcriptional activation. The RT-PCR detection results showed that wtSIRT1 reduced RANKL transcription under the conditions of apoptotic agent treatment. The finding that SIRT1 can regulate the physiological process of bone remodeling through the RANK/RANKL signaling pathway in osteoblasts under stress. The O-glycosylation and deacetylation activity of SIRT1 significantly increased, regulating the balance between osteoblast survival and apoptosis by deacetylation of key proteins such as RANKL.

Short-term effects of intravenous batroxobin in treatment of sudden sensorineural hearing loss: a propensity score-matched study.

Background: Sudden sensorineural hearing loss (SSNHL) can cause great panic in patients. Whether it is advantageous to add intravenous batroxobin in the treatment of SSNHL remains to be determined. This study aimed to compare the short-term efficacy of therapy combined with intravenous batroxobin and that without intravenous batroxobin in SSNHL patients. Methods: This retrospective study harvested the data of SSNHL patients hospitalized in our department from January 2008 to April 2021. The hearing levels on the admitted day (before treatment) and the discharge day were considered pre-treatment hearing and post-treatment hearing, respectively. The hearing gain was the difference value of pre-treatment hearing and post-treatment hearing. We used Siegel's criteria and the Chinese Medical Association of Otolaryngology (CMAO) criteria to evaluate hearing recovery. The complete recovery rate, overall effective rate, and hearing gain at each frequency were considered outcomes. Propensity score matching (PSM) was conducted to balance the baseline characteristics between the batroxobin group and the non-batroxobin group. Sensitivity analysis was carried out in flat-type and total-deafness SSNHL patients. Results: During the study period, 657 patients with SSNHL were admitted to our department. Among them, a total of 274 patients met the enrolled criteria of our study. After PSM, 162 patients (81 in each group) were included in the analysis. Once the hospitalized treatment was completed, the patients would be discharged the next day. Logistic regression analysis of the propensity score-matched cohort indicated that both the complete recovery rates [Siegel's criteria, OR: 0.734, 95% CI: 0.368-1.466, p = 0.381; CMAO criteria, OR: 0.879, 95% CI: 0.435-1.777, p = 0.720] and the overall effective rates [Siegel's criteria and CMAO criteria, OR: 0.741, 95% CI: 0.399-1.378, p = 0.344] were not significantly different between the two treatment groups. Sensitivity analysis has shown similar results. For flat-type and total-deafness SSNHL patients, no significant difference was found in post-treatment hearing gain at each frequency between the two groups after PSM. Conclusion: There was no significant difference in short-term hearing outcomes between treatment with batroxobin and treatment without batroxobin in SSNHL patients by Siegel's and CMAO criteria after PSM. Future studies for better therapy regimens of SSNHL are still needed.

Probiotic and glutamine treatments attenuate alcoholic liver disease in a rat model.

The pathogenesis underlying alcoholic liver disease (ALD), which is often a result of alcohol abuse, currently remains unclear. Previous studies have reported that enteric dysbiosis serves an important role in the pathogenesis of ALD. The present study aimed to investigate the effects of glutamine and probiotics on a rat model of alcoholic liver disease (ALD). Sixty male Sprague-Dawley rats were randomly divided into 6 groups including control (C), alcohol (M), alcohol + Golden Bifido (T), alcohol + glutamine (G), alcohol + Medilac-S® (N) and alcohol + Golden Bifido + glutamine (L). Histology, body weight (BW), triglycerides (TG), serum aspartate transaminase (AST), alanine aminotransferase (ALT), tumor necrosis factor (TNF-α), interleukin-6 (IL-6), diamine oxidase (DAO), occludin, endotoxin and D-lactate levels were assessed whilst changes in the gut flora were evaluated and compared. Results determined that all probiotic and glutamine treatments elevated the abnormally decreased BW and occludin levels whilst the abnormal elevated serum AST, ALT, TG, IL-6, TNF-α, DAO, endotoxin and D-lactate levels were significantly reduced following chronic ethanol consumption. Histopathological observation of the liver demonstrated that probiotic and glutamine treatments attenuated liver damage induced by alcohol. Moreover, sequencing determined that there was a reduction in Firmicutes as well as an increase in Actinobacteria, Proteobacteria and Porphyromonadaceae abundance in the ALD group compared with the healthy controls. However, these changes were prevented by glutamine and probiotic therapy. In conclusion, the present results suggested that probiotics and glutamine ameliorated ALD by suppressing inflammation and regulating the gut microbiota. Therefore, probiotic and glutamine treatments can potentially serve as therapies for the prevention and treatment of ALD.

Down-regulation of G protein-coupled receptor 137 by RNA interference inhibits cell growth of two hepatoma cell lines.

G protein-coupled receptors (GPCRs) are important signal transduction mediators and pharmacological therapeutic targets. G protein-coupled receptor 137 (GPR137) was initially reported as a novel orphan GPCR around 10 years ago. Some orphan GPCRs have been implicated in cancer cell proliferation and migration. The aim of this study is to investigate the role of GPR137 in hepatocellular carcinoma (HCC). GPR137 is widely expressed in several human HCC cell lines, as determined by real-time PCR. We then applied lentivirus mediated RNA interference (RNAi) to knock down GPR137 expression in two HCC cell lines HepG2 and Bel7404. Depletion of GPR137 remarkably inhibited cell proliferation and colony formation capacity. Knockdown of GPR137 in HepG2 cells led to cell cycle arrest at G0/G1 phase and G2/M phase, and induced cell apoptosis, as determined by flow cytometry analysis, which contributed to cell growth inhibition. Our findings suggested that GPR137 could facilitate HCC cell proliferation and thus promote hepatocarcinogenesis.