Mitophagy is a selective autophagic process, essential for cellular homeostasis, that eliminates dysfunctional mitochondria. Activated by inner membrane depolarization, it plays an important role during development and is fundamental in highly differentiated post-mitotic cells that are highly dependent on aerobic metabolism, such as neurons, muscle cells, and hepatocytes. Both defective and excessive mitophagy have been proposed to contribute to age-related neurodegenerative diseases, such as Parkinson’s and Alzheimer’s diseases, metabolic diseases, vascular complications of diabetes, myocardial injury, muscle dystrophy, and liver disease, among others. Pharmacological or dietary interventions that restore mitophagy homeostasis and facilitate the elimination of irreversibly damaged mitochondria, thus, could serve as potential therapies in several chronic diseases. However, despite extraordinary advances in this field, mainly derived from in vitro and preclinical animal models, human applications based on the regulation of mitochondrial quality in patients have not yet been approved. In this review, we summarize the key selective mitochondrial autophagy pathways and their role in prevalent chronic human diseases and highlight the potential use of specific interventions.

The mealworm (Tenebrio molitor Linnaeus 1758) is gaining importance as one of the most popular edible insects. Studies focusing on its bioactivities are increasing, although alternative forms of consumption other than the whole insect or flour, such as bioactive non-protein extracts, remain underexplored. Furthermore, the incidence of metabolic syndrome-related pathologies keeps increasing, hence the importance of seeking novel natural sources for reducing the impact of certain risk factors. The aim was to study the potential of a non-protein mealworm extract on metabolic syndrome-related pathologies, obtained with ethanol:water (1:1, v/v) by ultrasound-assisted extraction. We characterized the extract by gas-chromatography mass-spectrometry and assessed its hypolipidemic potential, its ability to scavenger free radicals, to attenuate the inflammatory response in microglial cells, to affect mitochondrial respiration and to enhance insulin sensitivity in mouse hepatocytes. The extract contained fatty acids, monoglycerides, amino acids, certain acids and sugars. The mealworm extract caused a 30% pancreatic lipase inhibition, 80% DPPH· scavenging activity and 55.9% reduction in the bioaccessibility of cholesterol (p = 0.009). The extract was effective in decreasing iNOS levels, increasing basal, maximal and ATP coupled respiration as well as enhancing insulin-mediated AKT phosphorylation at low insulin concentrations (p < 0.05). The potential of a non-protein bioactive mealworm extract against metabolic syndrome-related pathologies is shown, although further studies are needed to elucidate the mechanisms and relationship with compounds.

Understanding the complex biological processes of cells in culture, particularly those related to metabolism, can be biased by culture conditions, since the choice of energy substrate impacts all of the main metabolic pathways. When glucose is replaced by galactose, cells decrease their glycolytic flux, working as an in vitro model of limited nutrient availability. However, the effect of these changes on related physiological processes such as redox control is not well documented, particularly in endothelial cells, where mitochondrial oxidation is considered to be low. We evaluated the differences in mitochondrial dynamics and function in endothelial cells exposed to galactose or glucose culture medium. We observed that cells maintained in galactose-containing medium show a higher mitochondrial oxidative capacity, a more fused mitochondrial network, and higher intercellular coupling. These factors are documented to impact the cellular response to oxidative stress. Therefore, we analyzed the levels of two main redox regulators and found that bovine aortic endothelial cells (BAEC) in galactose media had higher levels of FOXO3 and lower levels of Nrf2 than those in glucose-containing media. Thus, cultures of endothelial cells in a galactose-containing medium may provide a more suitable target for the study of in vitro mitochondrial-related processes than those in glucose-containing media; the medium deeply influences redox signaling in these cells.

This study evaluated the intestinal effects of alkalinized filtered water in lean and obese adult Zucker rats. For 3 months, 12-week-old rats consumed either tap water or filtered alkalinized tap water from Madrid city. Weight gain was monitored, changes in metabolism were evaluated by indirect calorimetry, and total antioxidant capacity and levels of inflammatory mediators were measured in plasma. Feces were collected, their microbial composition was analyzed and histological analysis of the small and large intestine was performed, assessing the general state of the mucosa (MUC2), the inflammatory state (F4/80) and the presence of oxidative modifications in protein 4-Hydroxynonenal (4-HNE) by immunofluorescence (IF) and immunohistochemistry (IHC). The results obtained showed that the consumption of alkalinized filtered water improved the composition of the intestinal microbiome and the state of the intestinal mucosa, reducing both local and systemic inflammation and the level of oxidative stress. These changes were accompanied by a better maintenance of the oxidative status in rats. No differences were observed in antioxidant capacity nor in weight gain. The incorporation of probiotics in the diet had a significant impact on the microbiome. These effects were indicative of an improvement in general metabolic, oxidative and inflammatory status.

Understanding complex biological processes of cells in culture, particularly those related to metabolism, can be biased by culture conditions, since the choice of energy substrate impacts all main metabolic pathways. When glucose is replaced by galactose cells decrease their glycolytic flux, working as an in vitro model of limited nutrient availability. However, the effect of these changes on related physiological processes such as REDOX control is not well documented, particularly in endothelial cells where mitochondrial oxidation is considered to be low. We evaluated the differences in mitochondrial dynamics and function in endothelial cells exposed to galactose or glucose culture medium. We observed that cells maintained in galactose-containing medium show higher mitochondrial oxidative capacity, more fused mitochondrial network, and higher intercellular coupling. These factors are documented to impact the cellular response to oxidative stress. Therefore, we analyzed the levels of two main REDOX regulators and found that Bovine Aortic Endothelial Cells (BAEC) in galactose media had higher levels of FOXO3 and lower levels of Nrf2 than those with glucose in the media. Thus, culture of endothelial cells in galactose containing medium may provide a more suitable condition to study in vitro mitochondrial related processes than glucose media, and deeply influence REDOX signaling in these cells.

Colorectal cancer (CRC) is the third most commonly diagnosed cancer and one of the deadliest. Early diagnosis is crucial, but current screening methods are insufficient. Metabolic dysfunction is an important risk factor, and mitochondrial DNA (mtDNA) instability is a well characterized feature. Thus, plasma cell free DNA (cfDNA) ioffers a window of cost-effective diagnostic options. We analyzed tissue and blood samples in a cohort of 60 CRC patients, to find functional correlating features between systemic metabolism, intestinal mucosal mitochondrial dysfunction and tumor development. We found that subjects with advanced stage tumors (III-IV) had in their normal mucosa more mitochondria than those bearing early-stage tumors (I-II), but these mitochondria were more fragmented and perinuclear in subjects with advanced tumors. Furthermore, analysis of mtDNA stability showed a reduced MT-ND4/MT-ND1 ratio in the normal mucosa of subjects with advanced tumors compared to those with early-stage tumors, suggesting that these alterations may be related to disease development. The observation that similar trends could be noted in PBMCs and immune-metabolic expression patters in PBMCs were also different between early and advanced-tumor bearing subjects, supports their functional relevance. In the tumors, the instability in the region between MT-COX3 and MT-ND4, detected by qPCR with the oligonucleotide set named ND1v2 was higher in subjects with advanced tumors. Importantly, in plasma the levels of MT-ND4/nuDNA and ND1v2/nuDNA were also lower in advance-stage subjects, suggesting that their determination could be a relevant biomarker of disease development. Therefore, these results suggest that mtDNA alterations are strongly linked to CRC development. Early loss of MT-ND4 in the normal mucosa could be a key early event, driving the extension of the mtDNA stability beyond MT-ND4 that can be detected in advanced tumors. Importantly, these features can be identified in cfDNA from plasma samples and may be used as biomarkers.