Emerging role of mitochondrial DAMPs, aberrant mitochondrial dynamics and anomalous mitophagy in gut mucosal pathogenesis

Gastroduodenal inflammation and ulcerative injuries are increasing due to expanding socio-economic stress, unhealthy food habits-lifestyle, smoking, alcoholism and usage of medicines like non-steroidal anti-inflammatory drugs. In fact, gastrointestinal (GI) complications, associated with the prevailing COVID-19 pandemic, further, poses a challenge to global healthcare towards safeguarding the GI tract. Emerging evidences have discretely identified mitochondrial dysfunctions as common etiological denominators in diseases. However, it is worth realizing that mitochondrial dysfunctions are not just consequences of diseases. Rather, damaged mitochondria severely aggravate the pathogenesis thereby qualifying as perpetrable factors worth of prophylactic and therapeutic targeting. Oxidative and nitrosative stress due to endogenous and exogenous stimuli triggers mitochondrial injury causing production of mitochondrial damage associated molecular patterns (mtDAMPs), which, in a feed-forward loop, inflicts inflammatory tissue damage. Mitochondrial structural dynamics and mitophagy are crucial quality control parameters determining the extent of mitopathology and disease outcomes. Interestingly, apart from endogenous factors, mitochondria also crosstalk and in turn get detrimentally affected by gut pathobionts colonized during luminal dysbiosis. Although mitopathology is documented in various pre-clinical/clinical studies, a comprehensive account appreciating the mitochondrial basis of GI mucosal pathologies is largely lacking. Here we critically discuss the molecular events impinging on mitochondria along with the interplay of mitochondria-derived factors in fueling mucosal pathogenesis. We specifically emphasize on the potential role of aberrant mitochondrial dynamics, anomalous mitophagy, mitochondrial lipoxidation and ferroptosis as emerging regulators of GI mucosal pathogenesis. We finally discuss about the prospect of mitochondrial targeting for next-generation drug discovery against GI disorders.

Correlation between mitochondrial DNA 4977 bp deletion and presbycusis: A system review and meta-analysis

OBJECTIVE

Researchers have evaluated the associations between mitochondrial DNA (mtDNA) 4977 bp deletion and presbycusis. This study aimed to assess the differences of mtDNA 4977 bp deletion between presbycusis patients and controls by conducting a meta-analysis of published studies.

METHODS

Databases, including PubMed, Embase, Web of Science, China National Knowledge Infrastructure (CNKI), and Wanfang Data were searched to collect case-control studies on the correlation between mitochondrial DNA 4977 bp deletion and presbycusis. The research findings of related articles were collected according to the inclusion criteria. Pooled odds ratios (ORs) and corresponding confidence intervals (CIs) were calculated. Meanwhile, subgroup analysis was performed to examine the source of heterogeneity. Revman 5.3 and Stata 12.0 software were used for data synthesis.

RESULTS

Eight English and Chinese studies were included in the meta-analysis, the results of which showed that mitochondrial DNA 4977 bp deletion could increase the risk of presbycusis (OR = 8.16, 95% CI: 3.51-18.99), and the difference was statistically significant (P <. 01). Analysis of the polled OR showed the incidence of mtDNA 4977 bp deletion was 8.50 times higher in Asians with presbycusis than in the control group. And the OR in the studies of occidentals was 7.24. Sample source analysis was also performed with the sample source divided by temporal bone source and other sources (hair and blood). The OR was 4.18 and 22.36 for the temporal bone and other sources, respectively.

CONCLUSION

Mitochondrial DNA 4977 bp deletion could increase the risk of presbycusis.