Autophagy Contributes to the Rapamycin-Induced Improvement of Otitis Media

Cdh23 Gene Mutation-Induced Vestibular Dysfunction in Mice: Abnormal Stereocilia Bundle and Otolith Development and Activation of p53/FoxO Signaling Pathway

Vestibular dysfunction (VD) is increasingly acknowledged as a significant contributor to falls and deterioration in health. Cadherin 23 (Cdh23) serves as an essential protein responsible for facilitating the mechanical transduction processes in hair cells, and variations in this gene have been recognized as possible factor to auditory impairments and VD. The gene Cdh23 encodes glycoproteins that play a role in cell adhesion and are crucial for the development of stereocilia bundles. In this research, we generated CDH23 functional null mice (Cdh23V2J2/V2J2). Here, our findings indicated that Cdh23V2J2/V2J2 mice exhibited weakened balance and coordination abilities, characterized by rotation and head nodding movements. The development of stereocilia and otoliths was abnormal in these mice. Scanning electron microscopy (SEM) analysis revealed abnormal changes in the arrangement and length of stereocilia bundles in Cdh23V2J2/V2J2 mice compared to wild-type mice. The abnormal alterations of otolith shape in Cdh23V2J2/V2J2 mice also were observed, which was smaller in saccules but larger in utricles. Furthermore, we also observed that the number of vestibular hair cells (VHCs) decreased in Cdh23V2J2/V2J2 mice, along with significant activation of the p53 and FoxO signaling pathways at postnatal day 56 (P56). This study elucidates potential mechanisms, histopathological features, and resultant genomic alterations associated with VD in Cdh23V2J2/V2J2 mice, thereby establishing a scientific foundation for prospective vestibular rehabilitative interventions.

A 'torn bag mechanism' of small extracellular vesicle release via limiting membrane rupture of en bloc released amphisomes (amphiectosomes)

Recent studies showed an unexpected complexity of extracellular vesicle (EV) biogenesis pathways. We previously found evidence that human colorectal cancer cells in vivo release large multivesicular body-like structures en bloc. Here, we tested whether this large EV type is unique to colorectal cancer cells. We found that all cell types we studied (including different cell lines and cells in their original tissue environment) released multivesicular large EVs (MV-lEVs). We also demonstrated that upon spontaneous rupture of the limiting membrane of the MV-lEVs, their intraluminal vesicles (ILVs) escaped to the extracellular environment by a 'torn bag mechanism'. We proved that the MV-lEVs were released by ectocytosis of amphisomes (hence, we termed them amphiectosomes). Both ILVs of amphiectosomes and small EVs separated from conditioned media were either exclusively CD63 or LC3B positive. According to our model, upon fusion of multivesicular bodies with autophagosomes, fragments of the autophagosomal inner membrane curl up to form LC3B positive ILVs of amphisomes, while CD63 positive small EVs are of multivesicular body origin. Our data suggest a novel common release mechanism for small EVs, distinct from the exocytosis of multivesicular bodies or amphisomes, as well as the small ectosome release pathway.

Interactions between toll-like receptors signaling pathway and gut microbiota in host homeostasis

BACKGROUND

Toll-like receptors (TLRs) are a family of fundamental pattern recognition receptors in the innate immune system, constituting the first line of defense against endogenous and exogenous antigens. The gut microbiota, a collection of commensal microorganisms in the intestine, is a major source of exogenous antigens. The components and metabolites of the gut microbiota interact with specific TLRs to contribute to whole-body immune and metabolic homeostasis.

OBJECTIVE

This review aims to summarize the interaction between the gut microbiota and TLR signaling pathways and to enumerate the role of microbiota dysbiosis-induced TLR signaling pathways in obesity, inflammatory bowel disease (IBD), and colorectal cancer (CRC).

RESULTS

Through the recognition of TLRs, the microbiota facilitates the development of both the innate and adaptive immune systems, while the immune system monitors dynamic changes in the commensal bacteria to maintain the balance of the host-microorganism symbiosis. Dysbiosis of the gut microbiota can induce a cascade of inflammatory and metabolic responses mediated by TLR signaling pathways, potentially resulting in various metabolic and inflammatory diseases.

CONCLUSION

Understanding the crosstalk between TLRs and the gut microbiota contributes to potential therapeutic applications in related diseases, offering new avenues for treatment strategies in conditions like obesity, IBD, and CRC.

Exploring key genes and pathways associated with sex differences in autism spectrum disorder: integrated bioinformatic analysis

Autism spectrum disorder (ASD) is a heterogenous neurodevelopmental disorder marked by functional abnormalities in brain that causes social and linguistic difficulties. The incidence of ASD is more prevalent in males compared to females, but the underlying mechanism, as well as molecular indications for identifying sex-specific differences in ASD symptoms remain unknown. Thus, impacting the development of personalized strategy towards pharmacotherapy of ASD. The current study employs an integrated bioinformatic approach to investigate the genes and pathways uniquely associated with sex specific differences in autistic individuals. Based on microarray dataset (GSE6575) extracted from the gene expression omnibus, the dysregulated genes between the autistic and the neurotypical individuals for both sexes were identified. Gene set enrichment analysis was performed to ascertain biological activities linked to the dysregulated genes. Protein-protein interaction network analysis was carried out to identify hub genes. The identified hub genes were examined to determine their functions and involvement in the associated pathways using Enrichr. Additionally, hub genes were validated from autism-associated databases and the potential small molecules targeting the hub genes were identified. The present study utilized whole blood transcriptomic gene expression analysis data and identified 2211 and 958 differentially expressed unique genes in males and females respectively. The functional enrichment analysis revealed that male hub genes were functionally associated with RNA polymerase II mediated transcriptional regulation whereas female hub genes were involved in intracellular signal transduction and cell migration. The top male hub genes exhibited functional enrichment in tyrosine kinase signalling pathway. The pathway enrichment analysis of male hub genes indicates the enrichment of papillomavirus infection. Female hub genes were enriched in androgen receptor signalling pathway and functionally enriched in focal adhesion specific excision repair. Identified drug like candidates targeting these genes may serve as a potential sex specific therapeutics. Wortmannin for males, 5-Fluorouracil for females had the highest scores. Targeted and sex-specific pharmacotherapies may be created for the management of ASD. The current investigation identifies sex-specific molecular signatures derived from whole blood which may serve as a potential peripheral sex-specific biomarkers for ASD. The study also uncovers the possible pharmacological interventions against the selected genes/pathway, providing support in development of therapeutic strategies to mitigate ASD. However, experimental proofs on biological systems are warranted.

Ototoxicity of polystyrene nanoplastics in mice, HEI-OC1 cells and zebrafish

Polystyrene nanoplastics are a novel class of pollutants. They are easily absorbed by living organisms, and their potential toxicity has raised concerns. However, the impact of polystyrene nanoplastics on auditory organs remains unknown. Here, our results showed that polystyrene nanoplastics entered the cochlea of mice, HEI-OC1 cells, and lateral line hair cells of zebrafish, causing cellular injury and increasing apoptosis. Additionally, we found that exposure to polystyrene nanoplastics resulted in a significant elevation in the auditory brainstem response thresholds, a loss of auditory sensory hair cells, stereocilia degeneration and a decrease in expression of Claudin-5 and Occludin proteins at the blood-lymphatic barrier in mice. We also observed a significant decrease in the acoustic alarm response of zebrafish after exposure to polystyrene nanoplastics. Mechanistic analysis revealed that polystyrene nanoplastics induced up-regulation of the Nrf2/HO-1 pathway, increased levels of malondialdehyde, and decreased superoxide dismutase and catalase levels in cochlea and HEI-OC1 cells. Furthermore, we observed that the expression of ferroptosis-related indicators GPX4 and SLC7A11 decreased as well as increased expression of ACLS4 in cochlea and HEI-OC1 cells. This study also revealed that polystyrene nanoplastics exposure led to increased expression of the inflammatory factors TNF-α, IL-1β and COX2 in cochlea and HEI-OC1 cells. Further research found that the cell apoptosis, ferroptosis and inflammatory reactions induced by polystyrene nanoplastics in HEI-OC1 cells was reversed through the pretreatment with N-acetylcysteine, a reactive oxygen species inhibitor. Overall, our study first discovered and systematically revealed the ototoxicity of polystyrene nanoplastics and its underlying mechanism.

Autophagy Genes and Otitis Media Outcomes

Otitis media (OM) is a common cause of hearing loss in children that requires corrective surgery. Various studies have investigated the pathomechanisms and treatment of OM. Autophagy, an essential cellular recycling and elimination mechanism implicated in various diseases, is known to play an important role in the pathogenesis of OM. Here, we conducted a literature review on autophagy in OM, highlighting the relationship between expression patterns of autophagy-related factors and pathophysiological and clinical aspects of OM. We summarized the existing research results on the expression of autophagy-related factors in acute OM (AOM), OM with effusion (OME), chronic OM (COM) with cholesteatoma, and COM without cholesteatoma (CholeOM) in animals and humans. Autophagy-related factors are expressed in the middle ear mucosa or fluid of AOM, effusion of OME, granulation tissue of COM, and cholesteatoma of CholeOM. Among ATGs and other autophagy-related factors, the most extensively studied in relation to the pathogenesis of OM are mTOR, LC3II/I, PI3K, Beclin-1, FLIP, Akt, and Rubicon. Expression of autophagy-related factors is associated with AOM, OME, COM, and CholeOM. Inadequate expression of these factors or a decrease/increase in autophagy responses can result in OM, underscoring the critical role of ATGs and related factors in the pathogenesis of OM.

Genetic Evidence Supporting Causal Roles of mTOR-Dependent Proteins in Rheumatic Fever: A Two-Sample Randomized Mendelian Study

BACKGROUND

The expression of signaling molecules downstream of the mammalian target of rapamycin (mTOR) is dysregulated in patients with rheumatic fever (RF), but the causality of mTOR on RF remains unknown. This study aimed to investigate the causal effects of the mTOR-dependent proteins in RF.

METHODS

The summary data for targets of the mTOR signaling were acquired from the publicly available INTERVAL study GWAS data. Data on RF have been obtained from the Integrated Epidemiology Unit GWAS database (38,209 cases and 156,711 healthy controls). A two-sample Mendelian randomization (MR) study was conducted to examine the association of RF risk and mTOR-dependent proteins (EIF4EBP2, EIF-4E, EIF-4G, EIF-4A, RP-S6K, and ATG7), including the inverse-variance weighted (IVW) method, MR-Egger, and weighted median, which was followed by sensitivity analyses.

RESULTS

RP-S6K is associated with a lowered risk of RF with an odds ratio (OR) of 0.97, 95% confidence interval (95% CI) of 0.94-0.99 (p = 0.027). In contrast, ATG7 accounts for higher risk of RF with an OR of 1.05 (95% CI = 1.00-1.12, p = 0.047). No apparent heterogeneity and no horizontal pleiotropy were observed in the sensitivity analysis (p > 0.05). No statistical significance was identified for levels of EIF4A, EIF4G, EIF4E-BP2, and RP-S6K with RF risk (p > 0.05).

CONCLUSION

MR found robust evidence of a causal association between RF and mTOR. RP-S6K and ATG7 may be targeted for intervention by repurposing existing therapeutics to reduce the risk of RF.