Mitochondrial disease and endocrine dysfunction

Evaluation of the MDM-score system for screening mitochondrial diabetes mellitus in newly diagnosed diabetes patients: a multi-center cohort study in China

Objective

To evaluate the performance of MDM-score system in screening for mitochondrial diabetes mellitus (MDM) with m.3243A>G mutation in newly diagnosed diabetes.

Methods

From 2015 to 2017, we recruited 5130 newly diagnosed diabetes patients distributed in 46 hospitals in China. Their DNA samples were subjected to targeted sequencing of 37 genes, including the mitochondrial m.3243A>G mutation. Based on this cohort, we analyzed the clinical characteristics of MDM and type 2 diabetes (T2DM), and evaluated the overall efficacy of the MDM-score through ROC curve analysis.

Results

MDM patients were diagnosed at a younger age (P =0.002) than T2DM patients. They also had a higher proportion of females, lower body mass index, lower height, lower weight, lower systolic blood pressure, and lower fasting C-peptide (P < 0.05). Among 48 MDM patients, the m.3243A>G heteroplasmy level was higher in MDM score ≥ 3 than in MDM score < 3 (P = 0.0281). There were 23 cases with MDM-score ≥ 3 in clinical T2DM, with an AUC of 0.612 (95% CI: 0.540-0.683, P <0.001) on ROC curve analysis, yielding sensitivity of 47.9%, specificity of 74.4%, positive predictive value of 1.9%, and negative predictive value of 99.3%. This suggests that almost half of MDM patients can be identified by the MDM score system.

Conclusions

The MDM-score is effective for screening MDM in newly diagnosed clinical T2DM, and some metrics may help to improve its performance in the future, thereby assisting clinicians in identifying suitable patients for genetic testing, and preventing misdiagnosis and mismanagement of MDM patients.

Chemically engineered exogenous organic reactions in living cells for in situ fluorescence imaging and biomedical applications

The unique microenvironment within living cells, characterized by high glutathione levels, reactive oxygen species concentrations, and active enzymes, facilitates the execution of chemical reactions. Recent advances in organic chemistry and chemical biology have leveraged living cells as reactors for chemical synthesis. This review summarizes recent reports on key intracellular in situ synthesis processes, including the synthesis of near-infrared fluorescent dyes, intracellular oxidative cross-linking, bioorthogonal reactions, and intracellular polymerization reactions. These methods have been applied to fluorescence imaging, tumor treatment, and the enhancement of biological functions. Finally, we discuss the challenges and opportunities in the field of in situ intracellular synthesis. We aim to guide the design of chemical molecules for in situ synthesis, improving the efficiency and control of artificial reactions in living cells, and ultimately achieving cell factory-like exogenous biological synthesis, biological function enhancement, and biomedical applications.

Mitochondrial Mutations in Cardiovascular Diseases: Preliminary Findings

Background/Objectives: Mitochondria are the main organelles for ATP synthesis able to produce energy for several different cellular activities. Cardiac cells require high amounts of energy and, thus, they contain a high number of mitochondria. Consequently, mitochondrial dysfunction in these cells is a crucial factor for the development of cardiovascular diseases. Mitochondria constitute central regulators of cellular metabolism and energy production, producing approximately 90% of the cells' energy needs in the form of ATP via oxidative phosphorylation. The mitochondria have their own circular, double-stranded DNA encoding 37 genes. Any mitochondrial DNA sequence anomaly may result in defective oxidative phosphorylation and lead to cardiac dysfunction. Methods: In this study, we investigated the potential association between mitochondrial DNA mutation and cardiovascular disease. Cardiac tissue and serum samples were collected from seven patients undergoing coronary artery bypass grafting. Total DNA was extracted from cardiac muscle tissue specimens and serum and each sample was subjected to polymerase chain reaction (PCR) to amplify the NADH dehydrogenase 1 (ND1) gene, which is part of the mitochondrial complex I enzyme complex and was screened for mutations. Results: We identified one patient with a homoplasmic A to G substitution mutation in cardiac tissue DNA and two patients with heteroplasmic A3397G mutation in serum DNA. Specifically, amplicon sequence analysis revealed a homoplasmic A3397G substitution in the ND1 gene in a tissue sample of the patient with ID number 1 and a heteroplasmic mutation in A3397G in serum samples of patients with ID numbers 3 and 6, respectively. The A to G substitution changes the amino acid from methionine (ATA) to valine (GTA) at position 31 of the ND1 gene. Conclusions: The detection of this novel mutation in patients with coronary artery disease may contribute to our understanding of the association between mitochondrial dysfunction and the disease, implying that mitochondria may be key players in the pathogenesis of cardiovascular diseases.

Society for endocrinology guideline for understanding, diagnosing and treating female hypogonadism

Female hypogonadism (FH) is a relatively common endocrine disorder in women of premenopausal age, but there are significant uncertainties and wide variation in its management. Most current guidelines are monospecialty and only address premature ovarian insufficiency (POI); some allude to management in very brief and general terms, and most rely upon the extrapolation of evidence from the studies relating to physiological estrogen deficiency in postmenopausal women. The Society for Endocrinology commissioned new guidance to provide all care providers with a multidisciplinary perspective on managing patients with all forms of FH. It has been compiled using expertise from Endocrinology, Primary Care, Gynaecology and Reproductive Health practices, with contributions from expert patients and a patient support group, to help clinicians best manage FH resulting from both POI and hypothalamo-pituitary disorders, whether organic or functional.

Regulatory Mechanism of Autophagy in Premature Ovarian Failure

Premature ovarian failure (POF) is intricately linked to cellular fates such as senescence, apoptosis, and impaired granulosa cell (GC) differentiation, each of which contributes to ovarian dysfunction and follicular depletion. Autophagy is essential in preventing POF by maintaining cellular homeostasis through the degradation and recycling of damaged organelles and proteins, thereby preserving ovarian function and preventing follicular depletion. Recent studies have revealed that the targeted regulation and disruption of autophagy through various molecular mechanisms ultimately lead to the pathogenesis of POF. In this review, we provide a comprehensive analysis of the disruption in regulatory mechanisms of autophagy contributing to POF. Specifically, we elucidate the molecular mechanisms that can be targeted to restore autophagy homeostasis, offering therapeutic potential for the treatment of POF.

Environmental endocrine disruptor-induced mitochondrial dysfunction: a potential mechanism underlying diabetes and its complications

Diabetes and its complications significantly affect individuals' quality of life. The etiology of diabetes mellitus and its associated complications is complex and not yet fully understood. There is an increasing emphasis on investigating the effects of endocrine disruptors on diabetes, as these substances can impact cellular processes, energy production, and utilization, ultimately leading to disturbances in energy homeostasis. Mitochondria play a crucial role in cellular energy generation, and any impairment in these organelles can increase susceptibility to diabetes. This review examines the most recent epidemiological and pathogenic evidence concerning the link between endocrine disruptors and diabetes, including its complications. The analysis suggests that endocrine disruptor-induced mitochondrial dysfunction-characterized by disruptions in the mitochondrial electron transport chain, dysregulation of calcium ions (Ca2+), overproduction of reactive oxygen species (ROS), and initiation of signaling pathways related to mitochondrial apoptosis-may be key mechanisms connecting endocrine disruptors to the development of diabetes and its complications.

Multiomics analysis reveals serine catabolism as a potential therapeutic target for MELAS

Mitochondrial disease is a devastating genetic disorder, with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) and m.3243A>G being the most common phenotype and genotype, respectively. The treatment for MELAS patients is still less effective. Here, we performed transcriptomic and proteomic analysis in muscle tissue of MELAS patients, and discovered that the expression of molecules involved in serine catabolism were significantly upregulated, and serine hydroxymethyltransferase 2 (SHMT2) increased significantly in both the mRNA and protein levels. The SHMT2 protein level was also increased in myoblasts with m.3243A>G mutation, which was transdifferentiated from patients derived fibroblasts, accompanying with the decreased nicotinamide adenine dinucleotide (NAD+)/reduced NAD+ (NADH) ratio and cell viability. After treating with SHMT2 inhibitor (SHIN1), the NAD+/NADH ratio and cell viability in MELAS myoblasts increased significantly. Taken together, our study indicates that enhanced serine catabolism plays an important role in the pathogenesis of MELAS and that SHIN1 can be a potential small molecule for the treatment of this disease.

Ultrabright Xanthene Fluorescence Probe for Mitochondrial Super-Resolution Imaging

Mitochondria are important organelles that provide energy for cellular physiological activities. Changes in their structures may indicate the occurrence of diseases, and the super-resolution imaging of mitochondria is of great significance. However, developing fluorescent probes for mitochondrial super-resolution visualization still remains challenging due to insufficient fluorescence brightness and poor stability. Herein, we rationally synthesized an ultrabright xanthene fluorescence probe Me-hNR for mitochondria-specific super-resolution imaging using structured illumination microscopy (SIM). The rigid structure of Me-hNR provided its ultrahigh fluorescence quantum yield of up to 0.92 and ultrahigh brightness of up to 16,000. Occupying the para-position of the O atom in the xanthene skeleton by utilizing the smallest methyl group ensured its excellent stability. The study of the photophysical process indicated that Me-hNR mainly emitted fluorescence via radiative decay, and nonradiative decay and inter-system crossing were rare due to the slow nonradiative decay rate and large energy gap (ΔEst = 0.55 eV). Owing to these excellent merits, Me-hNR can specifically light up mitochondria at ultralow concentrations down to 5 nM. The unprecedented spatial resolution for mitochondria with an fwhm of 174 nm was also achieved. Therefore, this ultrabright xanthene fluorescence probe has great potential in visualizing the structural changes of mitochondria and revealing the pathogenesis of related diseases using SIM.

Endocrine features of primary mitochondrial diseases

PURPOSE OF REVIEW

Primary mitochondrial diseases are one of the most prevalent groups of multisystem genetic disorders. Endocrinopathies associated with mitochondrial diseases may have clinical features that are distinct from the more common forms. We provide an overview of mitochondrial disorder genetics and phenotypes, focusing on recent studies regarding identification and treatment of associated endocrinopathies.

RECENT FINDINGS

Known endocrine phenotypes of mitochondrial disorders continue to expand, and now include growth hormone deficiency, hypogonadism, precocious puberty, hypoparathyroidism, hypo- and hyperthyroidism, diabetes, and adrenal insufficiency. Recent studies suggest several genotype-phenotype correlations, including those related to nuclear variants. Diagnosis is important, as special considerations should be made in the management of endocrinopathies in mitochondrial patients. Finally, new mitochondrial replacement strategies may soon be available for women interested in preventing mitochondrial disease transmission to offspring.

SUMMARY

Patients with multiple endocrinopathies or atypical endocrinopathies should be evaluated for primary mitochondrial disease, as a diagnosis may impact management of these individuals.

Generation of inducible mitophagy mice

Mitophagy is programmed selective autophagy of mitochondria and is important for mitochondrial quality control and cellular homeostasis. Mitochondrial dysfunction and impaired mitophagy are closely associated with various diseases, including heart failure and diabetes. To better understand the pathophysiological role of mitophagy, we generated doxycycline-inducible mitophagy mice using a synthetic mitophagy adaptor protein consisting of an outer mitochondrial membrane targeting sequence and an engineered LIR. To evaluate the activation of mitophagy upon doxycycline treatment, we also generated mitophagy reporter mito-QC mice in which mitochondria tandemly express mCherry and GFP, and only GFP signals are lost in acidic lysosomes subjected to mitophagy. With the ROSA26 promoter-driven rtTA, mitophagy was observed at least in heart, liver, and skeletal muscle. We investigated the relationship between mitophagy activation and pressure overload heart failure or high fat diet-induced obesity. Unexpectedly, we were unable to confirm the protective effect of mitophagy in these two pathological models. Further titration of the level of mitophagy induction is required to demonstrate the potency of the protective effects of mitophagy in disease models.

A Pair of Compound Heterozygous IARS2 Variants Manifesting West Syndrome and Electrolyte Disorders in a Chinese Patient

Background  Aminoacyl-tRNA synthetases (ARSs) are evolutionarily conserved enzymes that ensure the accuracy of the translation process. Isoleucyl-tRNA synthetase 2 ( IARS2 ) gene is a type of ARS that encodes mitochondrial isoleucine-tRNA synthetase. Pathogenic variants in the IARS2 gene are associated with mitochondrial disease which involves several patients presenting broad clinical phenotypes. These clinical phenotypes include West syndrome, Leigh syndrome, and Cataract, growth hormone deficiency, sensory neuropathy, sensorineural hearing loss, and skeletal dysplasia syndrome. Only 29 cases have been reported worldwide. The patient manifested recurrent convulsions, and specific clinical manifestations included electrolyte disorders and recurrent infections. Methods  Whole-exome sequencing was performed on the child with West syndrome. Three-dimensional structure reconstruction and thermodynamic stability prediction were performed to further analyze the relationship between variation and phenotype. Conclusion  This study further expands the clinical spectrum of IARS2 pathogenic variants. The case summaries help raise clinical awareness of IARS2 -associated disease and reduce misdiagnosis. Result  In this report, a 13-month-old girl was diagnosed with West syndrome and Leigh syndrome for 7 months. Compound heterozygous variants in the IARS2 gene (NM_018060.4), c.2450G>A (Arg817His) and copy number variation (NC_000001. 11: g. (220267549_220284289) del), were detected by WES. This study further expands the clinical spectrum of IARS2 pathogenic variants. The case summaries help raise clinical awareness of IARS2-associated disease and reduce misdiagnosis.

Endocrine Challenges in Myoclonic Epilepsy With Ragged Red Fibers Syndrome: A Case Report

Myoclonic epilepsy with ragged red fibers (MERRF) syndrome is a primary mitochondrial disorder characterized by myoclonus, epilepsy, ataxia, and muscle fiber abnormalities. While traditionally associated with neurological features, MERRF's multisystem nature extends to endocrine dysfunction, including diabetes mellitus, thyroid disorders, and adrenal abnormalities. This case report explores the multifaceted nature of MERRF syndrome by presenting the clinical journey of a 70-year-old woman who sought care at the endocrinology clinic due to coexisting Addison's disease and diabetes mellitus, marked by recurrent hypoglycemia and suboptimal metabolic control. Over time, she developed a history of myoclonic epilepsy, effectively managed with lamotrigine, along with mild sensory axonal polyneuropathy and ataxia. The patient was diagnosed with MERRF syndrome following her son's diagnosis, which had a severe form. This case underscores the intricate interplay between mitochondrial dysfunction and endocrine manifestations in MERRF syndrome, highlighting the importance of a comprehensive and multidisciplinary approach to patient care. MERRF syndrome's array of endocrine manifestations substantially impacts patients' quality of life and morbidity. A comprehensive approach, uniting endocrinologists, neurologists, geneticists, and other specialists, is essential for effective patient care. Further research is warranted to unravel the complex mitochondrial-endocrine interactions in MERRF syndrome, offering potential insights for improved management.

Red Flags in Primary Mitochondrial Diseases: What Should We Recognize?

Primary mitochondrial diseases (PMDs) are complex group of metabolic disorders caused by genetically determined impairment of the mitochondrial oxidative phosphorylation (OXPHOS). The unique features of mitochondrial genetics and the pivotal role of mitochondria in cell biology explain the phenotypical heterogeneity of primary mitochondrial diseases and the resulting diagnostic challenges that follow. Some peculiar features ("red flags") may indicate a primary mitochondrial disease, helping the physician to orient in this diagnostic maze. In this narrative review, we aimed to outline the features of the most common mitochondrial red flags offering a general overview on the topic that could help physicians to untangle mitochondrial medicine complexity.

Multi-omics analysis of the oncogenic role of optic atrophy 1 in human cancer

OBJECTIVE

To investigate the prognostic significance of optic atrophy 1 (OPA1) in pan-cancer and analyze the relationship between OPA1 and immune infiltration in cancer.

RESULTS

OPA1 exhibited high expression levels or mutations in various types of tumor cells, and its expression levels were significantly correlated with the survival rate of tumor patients. In different tumor tissues, there was a notable positive correlation between OPA1 expression levels and the infiltration of cancer-associated fibroblasts in the immune microenvironment. Additionally, OPA1 and its related genes were found to be involved in several crucial biological processes, including protein phosphorylation, protein import into the nucleus, and protein binding.

CONCLUSION

OPA1 is highly expressed or mutated in numerous tumors and is strongly associated with protein phosphorylation, patient prognosis, and immune cell infiltration. OPA1 holds promise as a novel prognostic marker with potential clinical utility across various tumor types.

METHODS

We examined OPA1 expression in pan-cancer at both the gene and protein levels using various databases, including Tumor Immune Estimation Resource 2.0 (TIMER 2.0), Gene Expression Profiling Interactive Analysis (GEPIA2), UALCAN, and The Human Protein Atlas (HPA). We utilized the Kaplan-Meier plotter and GEPIA datasets to analyze the relationship between OPA1 expression levels and patient prognosis. Through the cBioPortal database, we detected OPA1 mutations in tumors and examined their relationship with patient prognosis. We employed the TIMER 2.0 database to explore the correlation between OPA1 expression levels in tumor tissue and the infiltration of cancer-associated fibroblasts in the immune microenvironment. Furthermore, we conducted a gene search associated with OPA1 and performed enrichment analysis to identify the main signaling pathways and biological processes linked to them.

Adrenocortical function in patients with Single Large Scale Mitochondrial DNA Deletions: a retrospective single centre cohort study

OBJECTIVE

Single Large Scale Mitochondrial DNA Deletions (SLSMDs), Pearson Syndrome (PS) and Kearns-Sayre Syndrome (KSS), are systemic diseases with multiple endocrine abnormalities. The adrenocortical function has not been systematically investigated with a few anecdotal reports of overt adrenal insufficiency (AI). The study aimed to assess the adrenocortical function in a large cohort of SLSMDs.

DESIGN AND METHODS

A retrospective monocentric longitudinal study involved a cohort of 18 SLSMDs patients. Adrenocortical function was evaluated by baseline adrenocorticotrophic hormone (ACTH) and cortisol measurements and by high- (HDT) and low-dose (LDT) ACTH stimulation tests and compared with 92 healthy controls (HC).

RESULTS

Baseline adrenocortical function was impaired in 39% of patients and by the end of the study, 66% of PS and 25% of KSS showed an insufficient increase after ACTH stimulation, with cortisol deficiency due to primary AI in most PS and subclinical AI in KSS. Symptomatic AI was recorded in 44% of patients. Peak cortisol levels after ACTH stimulation tests were significantly lower in patients than in HC (P < .0001), with a more reduced response to LDT vs HDT (P < .05).

CONCLUSIONS

Our study highlights that cortisol deficiency due to primary AI represents a relevant part of the clinical spectrum in SLSMDs, with more severe impairment in PS than in KSS. Basal and after-stimulus assessment of adrenocortical axis should be early and regularly investigated to identify any degree of adrenocortical dysfunction. The study allowed the elaboration of a diagnostic process designed for the diagnosis, treatment, and follow-up of adrenocortical abnormalities in SLSMDs.

Novel Tu translation elongation factor, mitochondrial (TUFM) homozygous variant in a consanguineous family with premature ovarian insufficiency

Premature ovarian insufficiency (POI) is a clinical syndrome of ovarian dysfunction characterized by cessation of menstruation occurring before the age of 40 years. The genetic causes of idiopathic POI remain unclear. Here we recruited a POI patient from a consanguineous family to screen for potential pathogenic variants associated with POI. Genetic variants of the pedigree were screened using whole-exome sequencing analysis and validated through direct Sanger sequencing. A homozygous variant in TUFM (c.524G>C: p.Gly175Ala) was identified in this family. TUFM (Tu translation elongation factor, mitochondrial) is a nuclear-encoded mitochondrial protein translation elongation factor that plays a critical role in maintaining normal mitochondrial function. The variant position was highly conserved among species and predicted to be disease causing. Our in vitro functional studies demonstrated that this variant causes decreased TUFM protein expression, leading to mitochondrial dysfunction and impaired autophagy activation. Moreover, we found that mice with targeted Tufm variant recapitulated the phenotypes of human POI. Thus, this is the first report of a homozygous pathogenic TUFM variant in POI. Our findings highlighted the essential role of mitochondrial genes in folliculogenesis and ovarian function maintenance.

Hypoparathyroidism in children and adolescents

Hypoparathyroidism is characterized by insufficient parathyroid hormone (PTH) release from the parathyroid glands to maintain serum calcium level within normal limits and unresponsiveness of target tissues despite normal serum PTH level. Hypoparathyroidism is defined as low or inappropriately normal serum PTH level. In this narrative review, we discuss the etiology of hypoparathyroidism in children.

Obstetric involvement in mitochondrial disorders: A review

This is the first review about obstetric involvement in mitochondrial disorders (MIDs). The purpose of the review was to discuss recent advances and knowledge about the type and frequency of obstetric complications in MIDs. A narrative review for preferred reporting items was performed in MEDLINE, Current Contents, EMBASE, Web of Science, Web of Knowledge, LILACS, SCOPUS, and Google Scholar. The author searched for studies examining obstetric complications in patients with a definite MID. Obstetric complications described in MIDs include eclampsia, preeclampsia, intra uterine growth retardation, polyhydramnion, oligoamnion, decreased fetal movements, premature delivery, stillbirth, blow weakness, dystocia, breech presentation, retained placenta, postnatal hemorrhage, low birth weight, and early postnatal death. The most common of these complications are polyhydramnion, stillbirth, premature delivery, and low birth weight. The data show that some obstetric complications are more common in MIDs than in healthy females. MIDs can be associated with various obstetric complications. Some of these complications are more common in pregnant females with MID compared with healthy pregnant females. Obstetricians should be aware of MIDs and should know that pregnant females with a MID have an increased risk of developing complications during pregnancy or delivery.

Mitochondrial DNA abnormalities and metabolic syndrome

Metabolic syndrome (MetS) is a complex pathological condition that involves disrupted carbohydrate, protein, and fat metabolism in the human body, and is a major risk factor for several chronic diseases, including diabetes, cardiovascular disease, and cerebrovascular disease. While the exact pathogenesis of metabolic syndrome is not yet fully understood, there is increasing evidence linking mitochondrial dysfunction, which is closely related to the mitochondrial genome and mitochondrial dynamics, to the development of this condition. Recent advancements in genetic sequencing technologies have allowed for more accurate detection of mtDNA mutations and other mitochondrial abnormalities, leading to earlier diagnosis and intervention in patients with metabolic syndrome. Additionally, the identification of specific mechanisms by which reduced mtDNA copy number and gene mutations, as well as abnormalities in mtDNA-encoded proteins and mitochondrial dynamics, contribute to metabolic syndrome may promote the development of novel therapeutic targets and interventions, such as the restoration of mitochondrial function through the targeting of specific mitochondrial defects. Additionally, advancements in genetic sequencing technologies may allow for more accurate detection of mtDNA mutations and other mitochondrial abnormalities, leading to earlier diagnosis and intervention in patients with MetS. Therefore, strategies to promote the restoration of mitochondrial function by addressing these defects may offer new options for treating MetS. This review provides an overview of the research progress and significance of mitochondrial genome and mitochondrial dynamics in MetS.

The Qi-Bang-Yi-Shen formula ameliorates renal dysfunction and fibrosis in rats with diabetic kidney disease <em>via</em> regulating PI3K/AKT, ERK and PPARγ signaling pathways

Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease (CKD) and a growing public health problem worldwide. Losartan potassium (Los), an angiotensin II receptor blocker, has been used to treat DKD clinically. Recently, multi-herbal formula has been shown to exhibit therapeutic activities in DKD in China. Thus, we aimed to explore the protective effects of combination of Los and Qi-Bang-Yi-Shen formula (QBF) on DKD rats. Streptozotocin (STZ) injection was used to establish a rat model of DKD. Next, the bloodurea nitrogen (BUN), creatinine (CRE) and uric acid (UA) levels were detected in serum samples from DKD rats. Hematoxylin and eosin (H&E), periodic Acid Schiff (PAS) and Masson staining were performed to observe glomerular injury and glomerular fibrosis in DKD rats. In this study, we found that QBF or Los treatment could decrease serum BUN, CRE, UA levels and reduce urine albumin-to-creatinine ratio (ACR) in DKD rats. Additionally, QBF or Los treatment obviously inhibited glomerular mesangial expansion and glomerular fibrosis, attenuated glomerular injury in kidney tissues of DKD rats. Moreover, QBF or Los treatment significantly reduced PI3K, AKT and ERK1/2 protein expressions, but increased PPARγ level in kidney tissues of DKD rats. As expected, combined treatment of QBF and Los could exert enhanced reno-protective effects compared with the single treatment. Collectively, combination of QBF and Los could ameliorate renal injury and fibrosis in DKD rats via regulating PI3K/AKT, ERK and PPARγ signaling pathways. These findings highlight the therapeutic potential of QBF to prevent DKD progression.

Currently available therapies in mitochondrial disease

Mitochondrial diseases are a heterogeneous group of multisystem disorders caused by impaired mitochondrial function. These disorders occur at any age and involve any tissue, typically affecting organs highly dependent on aerobic metabolism. Diagnosis and management are extremely difficult due to various underlying genetic defects and a wide range of clinical symptoms. Preventive care and active surveillance are strategies to try to reduce morbidity and mortality by timely treatment of organ-specific complications. More specific interventional therapies are in early phases of development and no effective treatment or cure currently exists. A variety of dietary supplements have been utilized based on biological logic. For several reasons, few randomized controlled trials have been completed to assess the efficacy of these supplements. The majority of the literature on supplement efficacy represents case reports, retrospective analyses and open-label studies. We briefly review selected supplements that have some degree of clinical research support. In mitochondrial diseases, potential triggers of metabolic decompensation or medications that are potentially toxic to mitochondrial function should be avoided. We shortly summarize current recommendations on safe medication in mitochondrial diseases. Finally, we focus on the frequent and debilitating symptoms of exercise intolerance and fatigue and their management including physical training strategies.

Development and function of the fetal adrenal

The adrenal cortex undergoes multiple structural and functional rearrangements to satisfy the systemic needs for steroids during fetal life, postnatal development, and adulthood. A fully functional adrenal cortex relies on the proper subdivision in regions or 'zones' with distinct but interconnected functions, which evolve from the early embryonic stages to adulthood, and rely on a fine-tuned gene network. In particular, the steroidogenic activity of the fetal adrenal is instrumental in maintaining normal fetal development and growth. Here, we review and discuss the most recent advances in our understanding of embryonic and fetal adrenal development, including the known causes for adrenal dys-/agenesis, and the steroidogenic pathways that link the fetal adrenal with the hormone system of the mother through the fetal-placental unit. Finally, we discuss what we think are the major open questions in the field, including, among others, the impact of osteocalcin, thyroid hormone, and other hormone systems on adrenal development and function, and the reliability of rodents as models of adrenal pathophysiology.

Down regulation of NDUFS1 is involved in the progression of parenteral-nutrition-associated liver disease by increasing Oxidative stress

Parenteral nutrition (PN)-associated liver disease (PNALD) is a common and life-threatening complication of patients receiving PN. However, its definitive pathology remains unclear. Ubiquinone oxidoreductase core subunit S1 (NDUFS1), which is the largest core subunit of mitochondrial complex I, could alter the mitochondrial reactive oxygen species (ROS) formation. The purpose of this study was to investigate the role of NDUFS1 in the pathogenesis of PNALD and its underlying mechanism. We performed hepatic proteomics analysis of PNALD patients, and established a PNALD rat model to verify the role of oxidative stress, NDUFS1, pyrin inflammasome, and IL-1β in the progression of PNALD. Proteomics analysis revealed the NDUFS1 expression was decreased in PNALD patients, and the differentially espressed proteins were involved in mitochondrial respiratory chain complex Ⅰ. Treatment with MitoQ or overexpression of NDUFS1 can alleviate the progression of PNALD by reducing oxidative stress. The expression of pyrin, caspase-1, and IL-1β was increased in PN rats. Pharmacological antagonism of pyrin by colchicine can alleviate liver injury and hepatic steatosis. NDUFS1 prevents PNALD pathogenesis by regulating oxidative stress. Pyrin inflammasome and IL-1β may participate in the process of PNALD development by suppressing the transcription of MTTP and impairing the secretion of VLDL. Oxidative stress reduction may be employed as a strategy in the prevention and treatment of PNALD.

Adrenal Dysfunction in Mitochondrial Diseases

Cortisol is central to several homeostatic mechanisms including the stress and immune response. Adrenal insufficiency and impaired cortisol production leads to severe, potentially fatal disorders. Several fundamental stages of steroidogenesis occur within the mitochondria. These dynamic organelles not only contribute ATP for steroidogenesis, but also detoxify harmful by-products generated during cortisol synthesis (reactive oxygen species). Mutations in nuclear or mitochondrial DNA that impair mitochondrial function lead to debilitating multi-system diseases. Recently, genetic variants that impair mitochondrial function have been identified in people with isolated cortisol insufficiency. This review aimed to clarify the association between mitochondrial diseases and adrenal insufficiency to produce cortisol. Mitochondrial diseases are rare and mitochondrial diseases that feature adrenal insufficiency are even rarer. We identified only 14 cases of adrenal insufficiency in people with confirmed mitochondrial diseases globally. In line with previous reviews, adrenal dysfunction was most prevalent in mitochondrial deletion syndromes (particularly Pearson syndrome and Kearns-Sayre syndrome) and with point mutations that compromised oxidative phosphorylation. Although adrenal insufficiency has been reported with mitochondrial diseases, the incidence reflects that expected in the general population. Thus, it is unlikely that mitochondrial mutations alone are responsible for an insufficiency to produce cortisol. More research is needed into the pathogenesis of adrenal disease in these individuals.

Potential adverse outcome pathways with hazard identification of organophosphate esters

Data-driven analysis and pathway-based approaches contribute to reasonable arrangements of limited resources and laboratory tests for continuously emerging commercial chemicals, which provides opportunities to save time and effort for toxicity research. With the widespread usage of organophosphate esters (OPEs) on a global scale, the concentrations generally reached up to micromolar range in environmental media and even in organisms. However, potential adverse effects and toxicity pathways of OPEs have not been systematically assessed. Therefore, it is necessary to review the current situation, formulate the future research priorities, and characterize toxicity mechanisms via data-driven analysis. Results showed that the early toxicity studies focused on neurotoxicity, cytotoxicity, and metabolic disorders. Then the main focus shifted to the mechanisms of cardiotoxicity, endocrine disruption, hepatocytes, reproductive and developmental toxicity to vulnerable sub-populations, such as infants and embryos, affected by OPEs. In addition, several novel OPEs have been emerging, such as bis(2-ethylhexyl)-phenyl phosphate (HDEHP) and oxidation derivatives (OPAsO) generated from organophosphite antioxidants (OPAs), leading to multiple potential ecological and human health risks (neurotoxicity, hepatotoxicity, developmental toxicity, etc.). Notably, in-depth statistical analysis was promising in encapsulating toxicological information to develop adverse outcome pathways (AOPs) frameworks. Subsequently, network-centric analysis and quantitative weight-of-evidence (QWOE) approaches were utilized to construct and evaluate the putative AOPs frameworks of OPEs, showing the moderate confidences of the developed AOPs. In addition, frameworks demonstrated that several events, such as nuclear receptor activation, reactive oxygen species (ROS) production, oxidative stress, and DNA damage, were involved in multiple different adverse outcome (AO), and these AOs had certain degree of connectivity. This study brought new insights into facilitating the complement of AOP efficiently, as well as establishing toxicity pathways framework to inform risk assessment of emerging OPEs.

Emerging Roles of NDUFS8 Located in Mitochondrial Complex I in Different Diseases

NADH:ubiquinone oxidoreductase core subunit S8 (NDUFS8) is an essential core subunit and component of the iron-sulfur (FeS) fragment of mitochondrial complex I directly involved in the electron transfer process and energy metabolism. Pathogenic variants of the NDUFS8 are relevant to infantile-onset and severe diseases, including Leigh syndrome, cancer, and diabetes mellitus. With over 1000 nuclear genes potentially causing a mitochondrial disorder, the current diagnostic approach requires targeted molecular analysis, guided by a combination of clinical and biochemical features. Currently, there are only several studies on pathogenic variants of the NDUFS8 in Leigh syndrome, and a lack of literature on its precise mechanism in cancer and diabetes mellitus exists. Therefore, NDUFS8-related diseases should be extensively explored and precisely diagnosed at the molecular level with the application of next-generation sequencing technologies. A more distinct comprehension will be needed to shed light on NDUFS8 and its related diseases for further research. In this review, a comprehensive summary of the current knowledge about NDUFS8 structural function, its pathogenic mutations in Leigh syndrome, as well as its underlying roles in cancer and diabetes mellitus is provided, offering potential pathogenesis, progress, and therapeutic target of different diseases. We also put forward some problems and solutions for the following investigations.

Long term follow-up in two siblings with Sengers syndrome: Case report

Background

Sengers syndrome is characterized by congenital cataract, hypertrophic cardiomyopathy, mitochondrial myopathy, and lactic acidosis associated with mutations in AGK gene. Clinical course ranges from a severe fatal neonatal form, to a more benign form allowing survival into adulthood, to an isolated form of congenital cataract. Thus far few reported cases have survived the second decade at their latest examination, and no natural history data are available for the disease.

Case presentation

Here we provide a 20-year follow-up in two siblings with a benign form of Sengers syndrome, expanding the phenotypical spectrum of the disease by reporting a condition of ovarian agenesis.

Conclusion

To our knowledge, this report provides the first longitudinal data of Sengers syndrome patients.

Supplementary information

The online version contains supplementary material available at 10.1186/s13052-022-01370-y.

A Comprehensive Review on Beneficial Effects of Catechins on Secondary Mitochondrial Diseases

Mitochondria are the main sites for oxidative phosphorylation and synthesis of adenosine triphosphate in cells, and are known as cellular power factories. The phrase "secondary mitochondrial diseases" essentially refers to any abnormal mitochondrial function other than primary mitochondrial diseases, i.e., the process caused by the genes encoding the electron transport chain (ETC) proteins directly or impacting the production of the machinery needed for ETC. Mitochondrial diseases can cause adenosine triphosphate (ATP) synthesis disorder, an increase in oxygen free radicals, and intracellular redox imbalance. It can also induce apoptosis and, eventually, multi-system damage, which leads to neurodegenerative disease. The catechin compounds rich in tea have attracted much attention due to their effective antioxidant activity. Catechins, especially acetylated catechins such as epicatechin gallate (ECG) and epigallocatechin gallate (EGCG), are able to protect mitochondria from reactive oxygen species. This review focuses on the role of catechins in regulating cell homeostasis, in which catechins act as a free radical scavenger and metal ion chelator, their protective mechanism on mitochondria, and the protective effect of catechins on mitochondrial deoxyribonucleic acid (DNA). This review highlights catechins and their effects on mitochondrial functional metabolic networks: regulating mitochondrial function and biogenesis, improving insulin resistance, regulating intracellular calcium homeostasis, and regulating epigenetic processes. Finally, the indirect beneficial effects of catechins on mitochondrial diseases are also illustrated by the warburg and the apoptosis effect. Some possible mechanisms are shown graphically. In addition, the bioavailability of catechins and peracetylated-catechins, free radical scavenging activity, mitochondrial activation ability of the high-molecular-weight polyphenol, and the mitochondrial activation factor were also discussed.

Hypogonadism in Males With Genetic Neurodevelopmental Syndromes

Genetic syndromes that affect the nervous system may also disrupt testicular function, and the mechanisms for these effects may be interrelated. Most often neurological signs and symptoms predominate and hypogonadism remains undetected and untreated, while in other cases, a thorough evaluation of a hypogonadal male reveals previously unrecognized ataxia, movement disorder, muscle weakness, tremor, or seizures, leading to a syndromic diagnosis. Androgen deficiency in patients with neurological diseases may aggravate muscle weakness and fatigue and predispose patients to osteoporosis and obesity. The purpose of this mini review is to provide a current understanding of the clinical, biochemical, histologic, and genetic features of syndromes in which male hypogonadism and neurological dysfunction may coexist and may be encountered by the clinical endocrinologist.

Chlorinated organophosphorus flame retardants-induced mitochondrial abnormalities and the correlation with progesterone production in mLTC-1 cells

Environmental monitoring data have indicated that three chlorinated organophosphorus flame retardants (Cl-OPFRs), including tris(2-chloroethyl)-phosphate (TCEP), tris(2-chloropropyl)-phosphate (TCPP), and tris(1,3-dichloro-2-propyl)-phosphate (TDCPP) are the predominant chemicals in various environmental matrices and exhibit reproductive endocrine disrupting activities. Currently, mitochondrial abnormality is a new paradigm for evaluating chemical-mediated cell dysfunction. However, a comprehensive correlation between these two aspects of Cl-OPFRs remains unclear. In this research, the effects of TCEP, TCPP, and TDCPP on progesterone production and mitochondrial impairment were investigated by using mouse Leydig tumor cells (mLTC-1). The half maximal inhibitory concentration (IC₅₀) values at 48 h exposure indicated that the rank order of anti-androgenic activity was TDCPP > TCPP. Whereas, TCEP exhibited elevation of progesterone production. At concentrations close to IC₅₀ of progesterone production by TCPP and TDCPP, the elevation of intracellular reactive oxygen species (ROS), depletion of mitochondrial membrane potential (MMP), reduction of cellular adenosine triphosphate (ATP) content, and alteration of mitochondrial structures was observed. In addition, the expression of main genes related to progesterone synthesis was dramatically down-regulated by TCPP and TDCPP treatments. These results imply that the inhibition effect of TCPP and TDCPP on progesterone production might be related to mitochondrial damage and down-regulated steroidogenic genes.

Management of a Girl With Delayed Puberty and Elevated Gonadotropins

A girl presenting with delayed puberty and elevated gonadotropins may have a range of conditions such as Turner syndrome (TS), primary ovarian insufficiency (POI), and 46,XY disorders of sexual development (DSD). An organized and measured approach to investigation can help reach a timely diagnosis. Management of young people often requires specialist multidisciplinary input to address the endocrine and nonendocrine features of these complex conditions, as well as the psychological challenges posed by their diagnosis. Next-generation sequencing within the research setting has revealed several genetic causes of POI and 46,XY DSD, which may further facilitate an individualized approach to care of these young people in the future. Pubertal induction is required in many and the timing of this may need to be balanced with other issues specific to the condition (eg, allowing time for information-sharing in 46,XY DSD, optimizing growth in TS). Shared decision-making and sign-posting to relevant support groups from the outset can help empower young people and their families to manage these conditions. We describe 3 clinical vignettes of girls presenting with delayed puberty and hypergonadotropic amenorrhea and discuss their clinical management in the context of current literature and guidelines.

β-cell dynamics in type 2 diabetes and in dietary and exercise interventions

Pancreatic β-cell dysfunction and insulin resistance are two of the major causes of type 2 diabetes (T2D). Recent clinical and experimental studies have suggested that the functional capacity of β-cells, particularly in the first phase of insulin secretion, is a primary contributor to the progression of T2D and its associated complications. Pancreatic β-cells undergo dynamic compensation and decompensation processes during the development of T2D, in which metabolic stresses such as endoplasmic reticulum stress, oxidative stress, and inflammatory signals are key regulators of β-cell dynamics. Dietary and exercise interventions have been shown to be effective approaches for the treatment of obesity and T2D, especially in the early stages. Whilst the targeted tissues and underlying mechanisms of dietary and exercise interventions remain somewhat vague, accumulating evidence has implicated the improvement of β-cell functional capacity. In this review, we summarize recent advances in the understanding of the dynamic adaptations of β-cell function in T2D progression and clarify the effects and mechanisms of dietary and exercise interventions on β-cell dysfunction in T2D. This review provides molecular insights into the therapeutic effects of dietary and exercise interventions on T2D, and more importantly, it paves the way for future research on the related underlying mechanisms for developing precision prevention and treatment of T2D.

TAZ ameliorates the microglia-mediated inflammatory response via the Nrf2-ROS-NF-κB pathway

Transcriptional co-activator with PDZ-binding motif (TAZ), one of core modules of the Hippo pathway, involves inflammatory cell infiltration in the liver, but little information is available regarding its physiological function in the microglia-mediated inflammatory response. Here we revealed that activation of TAZ prevented microglia production of proinflammatory cytokines, indicating TAZ’s importance in anti-inflammation. After translocation into the nucleus, TAZ interacted with transcriptional enhanced associate domain (TEAD) and bound to the promoter of nuclear factor erythroid 2-related factor 2 (Nrf2), whose blockage caused inability of TAZ to improve inflammation, implying that Nrf2 is a direct target of TAZ. Further analysis showed that TAZ induced Nrf2 nuclear translocation to enhance antioxidant capacity with attenuation of oxidative stress and the inflammatory response. Under inflammatory conditions, TAZ impeded mitochondrial dysfunction, as indicated by amelioration of ATP levels, mtDNA copy numbers, and mitochondrial membrane potential with an obvious reduction in mitochondrial superoxide, but this impediment was neutralized by blockage of Nrf2. TAZ hindered opening of the mitochondrial permeability transition pore, restrained release of cytochrome c from mitochondria into the cytosol, and was sufficient to rescue microglia from apoptosis dependent on Nrf2. Nrf2 acted as a downstream target of TAZ to repress NF-κB activation by enhancing antioxidant capacity. Collectively, TAZ might ameliorate the microglia-mediated inflammatory response through the Nrf2-reactive oxygen species (ROS)-nuclear factor κB (NF-κB) pathway.

Is Type 2 Diabetes a Primary Mitochondrial Disorder?

Diabetes mellitus is the most common endocrine disturbance in inherited mitochondrial diseases. It is essential to increase awareness of the correct diagnosis and treatment of diabetes in these patients and screen for the condition in family members, as diabetes might appear with distinctive clinical features, complications and at different ages of onset. The severity of mitochondrial-related diabetes is likely to manifest on a large scale of phenotypes depending on the location of the mutation and whether the number of affected mitochondria copies (heteroplasmy) reaches a critical threshold. Regarding diabetes treatment, the first-choice treatment for type 2 diabetes (T2D), metformin, is not recommended because of the risk of lactic acidosis. The preferred treatment for diabetes in patients with mitochondrial disorders is SGLT-2i and mitochondrial GLP-1-related substances. The tight relationship between mitochondrial dysfunction, reduced glucose-stimulated insulin secretion (GSIS), and diabetes development in human patients is acknowledged. However, despite the well-characterized role of mitochondria in GSIS, there is a relative lack of data in humans implicating mitochondrial dysfunction as a primary defect in T2D. Our recent studies have provided data supporting the significant role of the mitochondrial respiratory-chain enzyme, cytochrome c oxidase (COX), in regulating GSIS in a rodent model of T2D, the Cohen diabetic sensitive (CDs) rat. The nutritionally induced diabetic CDs rat demonstrates several features of mitochondrial diseases: markedly reduced COX activity in several tissues, increased reactive oxygen production, decreased ATP generation, and increased lactate dehydrogenase expression in islets. Moreover, our data demonstrate that reduced islet-COX activity precedes the onset of diabetes, suggesting that islet-COX deficiency is the primary defect causing diabetes in this model. This review examines the possibility of including T2D as a primary mitochondrial-related disease. Understanding the critical interdependence between diabetes and mitochondrial dysfunction, centering on the role of COX, may open novel avenues to diagnose and treat diabetes in patients with mitochondrial diseases and mitochondrial dysfunction in diabetic patients.

Endocrine Manifestations and New Developments in Mitochondrial Disease

Mitochondrial diseases are a group of common inherited diseases causing disruption of oxidative phosphorylation. Some patients with mitochondrial disease have endocrine manifestations, with diabetes mellitus being predominant but also include hypogonadism, hypoadrenalism, and hypoparathyroidism. There have been major developments in mitochondrial disease over the past decade that have major implications for all patients. The collection of large cohorts of patients has better defined the phenotype of mitochondrial diseases and the majority of patients with endocrine abnormalities have involvement of several other systems. This means that patients with mitochondrial disease and endocrine manifestations need specialist follow-up because some of the other manifestations, such as stroke-like episodes and cardiomyopathy, are potentially life threatening. Also, the development and follow-up of large cohorts of patients means that there are clinical guidelines for the management of patients with mitochondrial disease. There is also considerable research activity to identify novel therapies for the treatment of mitochondrial disease. The revolution in genetics, with the introduction of next-generation sequencing, has made genetic testing more available and establishing a precise genetic diagnosis is important because it will affect the risk for involvement for different organ systems. Establishing a genetic diagnosis is also crucial because important reproductive options have been developed that will prevent the transmission of mitochondrial disease because of mitochondrial DNA variants to the next generation.

Electronic Cigarette Use and the Risk of Cardiovascular Diseases

Electronic cigarettes or e-cigarettes are the most frequently used tobacco product among adolescents. Despite the widespread use of e-cigarettes and the known detrimental cardiac consequences of nicotine, the effects of e-cigarettes on the cardiovascular system are not well-known. Several in vitro and in vivo studies delineating the mechanisms of the impact of e-cigarettes on the cardiovascular system have been published. These include mechanisms associated with nicotine or other components of the aerosol or thermal degradation products of e-cigarettes. The increased hyperlipidemia, sympathetic dominance, endothelial dysfunction, DNA damage, and macrophage activation are prominent effects of e-cigarettes. Additionally, oxidative stress and inflammation are unifying mechanisms at many levels of the cardiovascular impairment induced by e-cigarette exposure. This review outlines the contribution of e-cigarettes in the development of cardiovascular diseases and their molecular underpinnings.

COVID-19-Related Outcomes in Primary Mitochondrial Diseases: An International Study

BACKGROUND AND OBJECTIVES

To identify factors associated with severe coronavirus disease 2019 (COVID-19), defined by hospitalization status, in patients with primary mitochondrial diseases (PMDs), thereby enabling future risk stratification and informed management decisions.

METHODS

We undertook a cross-sectional, international, registry-based study. Data were extracted from the International Neuromuscular COVID-19 Database and collected between May 1, 2020, and May 31, 2021. The database included subjects with (1) PMD diagnosis (any age), clinically/histopathologically suspected and/or genetically confirmed; and (2) COVID-19 diagnosis classified as "confirmed", "probable", or "suspected" based on World Health Organization definitions. The primary outcome was hospitalization because of COVID-19. We collected demographic information, smoking status, coexisting comorbidities, outcomes after COVID-19 infection, and PMD genotype-phenotype. Baseline status was assessed using the modified Rankin scale (mRS) and the Newcastle Mitochondrial Disease Adult Scale (NMDAS).

RESULTS

Seventy-nine subjects with PMDs from 10 countries were included (mean age 41.5 ± 18 years): 25 (32%) were hospitalized, 48 (61%) recovered fully, 28 (35%) improved with sequelae, and 3 (4%) died. Statistically significant differences in hospitalization status were observed in baseline status, including the NMDAS score (p = 0.003) and mRS (p = 0.001), presence of respiratory dysfunction (p < 0.001), neurologic involvement (p = 0.003), and more than 4 comorbidities (p = 0.002). In multivariable analysis, respiratory dysfunction was independently associated with COVID-19 hospitalization (odds ratio, 7.66; 95% CI, 2-28; p = 0.002).

DISCUSSION

Respiratory dysfunction is an independent risk factor for severe COVID-19 in PMDs while high disease burden and coexisting comorbidities contribute toward COVID-19-related hospitalization. These findings will enable risk stratification and informed management decisions for this vulnerable population.

Horizontal mtDNA transfer between cells is common during mouse development

Cells transmit their genomes vertically to daughter cells during cell divisions. Here, we demonstrate the occurrence and extent of horizontal mitochondrial (mt)DNA acquisition between cells that are not in a parent-offspring relationship. Extensive single-cell sequencing from various tissues and organs of adult chimeric mice composed of cells carrying distinct mtDNA haplotypes showed that a substantial fraction of individual cardiomyocytes, neurons, glia, intestinal, and spleen cells captured donor mtDNA at high levels. In addition, chimeras composed of cells with wild-type and mutant mtDNA exhibited increased trafficking of wild-type mtDNA to mutant cells, suggesting that horizontal mtDNA transfer may be a compensatory mechanism to restore compromised mitochondrial function. These findings establish the groundwork for further investigations to identify mtDNA donor cells and mechanisms of transfer that could be critical to the development of novel gene therapies.

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Individual cells in adult mouse chimeras acquire donor mtDNA horizontally

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Significant percentage of cardiomyocytes, neurons, and glia were heteroplasmic

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Donor mtDNA heteroplasmy in these cells can reach up to 50%

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Pathogenic mtDNA mutations may potentiate horizontal acquisition of wild-type mtDNA

Cytochrome c Oxidase Activity as a Metabolic Regulator in Pancreatic Beta-Cells

Pancreatic β-cells couple glucose-stimulated insulin secretion (GSIS) with oxidative phosphorylation via cytochrome c oxidase (COX), a mitochondrial respiratory-chain enzyme. The Cohen diabetic-sensitive (CDs) rats exhibit hyperglycemia when fed a diabetogenic diet but maintain normoglycemia on a regular diet. We have previously reported a decreased COX activity in CDs rats and explored its relevance for type 2 diabetes (T2D). In this study, we investigated the relation between COX activity in islets, peripheral-blood mononuclear cells (PBMCs), and GSIS during diabetes development in CDs rats fed a diabetogenic diet for 4, 11, 20, and 30 days and during reversion to normoglycemia in hyperglycemic CDs rats fed a reversion diet for 7, 11, and 20 days. An oral glucose-tolerance test was performed at different periods of the diets measuring blood glucose and insulin concentrations. COX activity was determined in islets and PBMCs isolated from rats at the different periods of the diets. We demonstrated a progressive reduction in COX activity in CDs-islets that correlated positively with the decreasing GSIS (R2 = 0.9691, p < 0.001) and inversely with the elevation in blood glucose levels (R2 = 0.8396, p < 0.001). Hyperglycemia was initiated when islet COX activity decreased below 46%. The reversion diet restored >46% of the islet COX activity and GSIS while re-establishing normoglycemia. Interestingly, COX activity in PBMCs correlated significantly with islet COX activity (R2 = 0.8944, p < 0.001). Our data support islet COX activity as a major metabolic regulator of β-cells function. The correlation between COX activity in PBMCs and islets may serve as a noninvasive biomarker to monitor β-cell dysfunction in diabetes.

Mitochondria Related Cell Death Modalities and Disease

Mitochondria are well known as the centre of energy metabolism in eukaryotic cells. However, they can not only generate ATP through the tricarboxylic acid cycle and oxidative phosphorylation but also control the mode of cell death through various mechanisms, especially regulated cell death (RCD), such as apoptosis, mitophagy, NETosis, pyroptosis, necroptosis, entosis, parthanatos, ferroptosis, alkaliptosis, autosis, clockophagy and oxeiptosis. These mitochondria-associated modes of cell death can lead to a variety of diseases. During cell growth, these modes of cell death are programmed, meaning that they can be induced or predicted. Mitochondria-based treatments have been shown to be effective in many trials. Therefore, mitochondria have great potential for the treatment of many diseases. In this review, we discuss how mitochondria are involved in modes of cell death, as well as basic research and the latest clinical progress in related fields. We also detail a variety of organ system diseases related to mitochondria, including nervous system diseases, cardiovascular diseases, digestive system diseases, respiratory diseases, endocrine diseases, urinary system diseases and cancer. We highlight the role that mitochondria play in these diseases and suggest possible therapeutic directions as well as pressing issues that need to be addressed today. Because of the key role of mitochondria in cell death, a comprehensive understanding of mitochondria can help provide more effective strategies for clinical treatment.

A novel homozygous variant in COX5A causes an attenuated phenotype with failure to thrive, lactic acidosis, hypoglycemia and short stature

Genetic defect in the nuclear encoded subunits of cytochrome c oxidase are very rare. To date, most deleterious variants affect the mitochondrially encoded subunits of complex IV and the nuclear genes encoded for assembly factors. A biallelic pathogenic variant in the mitochondrial complex IV subunit COX5A was previously reported in a couple of sibs with failure to thrive, lactic acidosis and pulmonary hypertension and a lethal phenotype. Here, we describe a second family with a 11-year-old girl presenting with failure to thrive, lactic acidosis, hypoglycemia and short stature. Clinical exome revealed the homozygous missense variant c.266T>G in COX5A, which produces a drop of the corresponding protein and a reduction of the COX activity. Compared to the previous observation, this girl showed an attenuated metabolic derangement without involvement of the cardiovascular system and neurodevelopment. Our observation confirms that COX5A recessive variants may cause mitochondrial disease and expands the associated phenotype to less severe presentations. This article is protected by copyright. All rights reserved.

Metabolic syndrome and cardiovascular diseases: Going beyond traditional risk factors

Metabolic syndrome (MS) is a chronic non-infective syndrome characterised clinically by a set of vascular risk factors that include insulin resistance, hypertension, abdominal obesity, impaired glucose metabolism, and dyslipidaemia. These risk factors are due to a pro-inflammatory state, oxidative stress, haemodynamic dysfunction, and ischaemia, which overlap in 'dysmetabolic' patients. This review aimed to evaluate the relationship between the traditional components of MS with cardiovascular disease (CVD), inflammation, and oxidative stress. MEDLINE-PubMed, EMBASE, and Cochrane databases were searched. Chronic low-grade inflammatory states and metaflammation are often accompanied by metabolic changes directly related to CVD incidence, such as diabetes mellitus, hypertension, and obesity. Moreover, the metaflammation is characterised by an increase in the serum concentration of pro-inflammatory cytokines, mainly interleukin-1 β (IL-1β), IL-6, and tumour necrosis factor-α (TNF-α), originating from the chronically inflamed adipose tissue and associated with oxidative stress. The increase of reactive oxygen species overloads the antioxidant systems causing post-translational alterations of proteins, lipids, and DNA leading to oxidative stress. Hyperglycaemia contributes to the increase in oxidative stress and the production of advanced glycosylation end products (AGEs) which are related to cellular and molecular dysfunction. Oxidative stress and inflammation are associated with cellular senescence and CVD. CVD should not be seen only as being triggered by classical MS risk factors. Atherosclerosis is a multifactorial pathological process with several triggering and aetiopathogenic mechanisms. Its medium and long-term repercussions, however, invariably constitute a significant cause of morbidity and mortality. Implementing preventive and therapeutic measures against oxy-reductive imbalances and metaflammation states has unquestionable potential for favourable clinical outcomes in cardiovascular medicine.

Use of Next-Generation Sequencing for Identifying Mitochondrial Disorders

Mitochondria are major contributors to ATP synthesis, generating more than 90% of the total cellular energy production through oxidative phosphorylation (OXPHOS): metabolite oxidation, such as the β-oxidation of fatty acids, and the Krebs's cycle. OXPHOS inadequacy due to large genetic lesions in mitochondrial as well as nuclear genes and homo- or heteroplasmic point mutations in mitochondrially encoded genes is a characteristic of heterogeneous, maternally inherited genetic disorders known as mitochondrial disorders that affect multisystemic tissues and organs with high energy requirements, resulting in various signs and symptoms. Several traditional diagnostic approaches, including magnetic resonance imaging of the brain, cardiac testing, biochemical screening, variable heteroplasmy genetic testing, identifying clinical features, and skeletal muscle biopsies, are associated with increased risks, high costs, a high degree of false-positive or false-negative results, or a lack of precision, which limits their diagnostic abilities for mitochondrial disorders. Variable heteroplasmy levels, mtDNA depletion, and the identification of pathogenic variants can be detected through genetic sequencing, including the gold standard Sanger sequencing. However, sequencing can be time consuming, and Sanger sequencing can result in the missed recognition of larger structural variations such as CNVs or copy-number variations. Although each sequencing method has its own limitations, genetic sequencing can be an alternative to traditional diagnostic methods. The ever-growing roster of possible mutations has led to the development of next-generation sequencing (NGS). The enhancement of NGS methods can offer a precise diagnosis of the mitochondrial disorder within a short period at a reasonable expense for both research and clinical applications.

IARS2-related disease manifesting as sideroblastic anemia and hypoparathyroidism: A case report

BACKGROUND

IARS2 (EC6.1.5) is a mitochondrial isoleucine-tRNA synthetase. Despite the fact that only fewer than 30 patients have been reported in the literature, mitochondrial disorders caused by pathogenic variants in the IARS2 gene (OMIM: 616007) have a very broad and variable clinical phenotype spectrum. We present a child who has sideroblastic anemia and hypoparathyroidism as a result of a previously unreported mutation in the IARS2 gene.

CASE PRESENTATION

A 14-year-old girl who had been anemic for 12 years was diagnosed with pure red cell aplasia (hemoglobin 42 g/L, reference range 110-160) at the age of 2. Her anemia was resistant to high-dose intravenous gamma globulin and cyclosporine therapy and required monthly blood transfusions to maintain normal hemoglobin levels. She developed cataracts at the age of 6 and was cured by phacoemulsification. At the age of 8, she visited the endocrine department, because of mental and physical retardation accompanied by repeated convulsions, and the antiepileptic treatment was ineffective. She was diagnosed with hypoparathyroidism. To control the convulsions, she was given calcitriol orally as well as large doses of calcium supplements. Due to severe growth and development delays, delayed sexual development, and hypokinesia at the age of 13.5Y, the parents agreed to a whole-exon gene sequencing test. IARS2 gene compound heterozygous variants c.2450G > A (p.Arg817His) and c.2511del (p.Leu838Phefs*69) were discovered. The girl was then diagnosed with IARS2-related disease and given a cocktail therapy of coenzyme Q₁₀, vitamin B₂, L-Carnitine and vitamin E. Although the child's clinical symptoms improved, she still experienced intermittent claudication and hip joint pain. The vitamin B₆ was discontinued after three months due to its ineffectiveness in treating anemia. Because the child's ferritin levels remained elevated, she was also prescribed long-term oral deferiprone therapy.

CONCLUSION

Our findings broaden the clinical and genetic spectrum of IARS2-associated disease, and case summaries help raise clinical awareness of IARS2-associated disease and reduce under- and misdiagnosis.