Blood mitochondrial DNA copy number: What are we counting?

Leukocyte Telomere Length and Mitochondrial DNA Copy Number in Treatment-Resistant Depression and Response to Electroconvulsive Therapy: A Pilot Longitudinal Study

OBJECTIVES

In this study, we investigated if changes in leukocyte telomere length (LTL) and mitochondrial DNA copy number (mtDNA-cn), 2 markers of cellular aging, are associated with treatment-resistant depression (TRD) and with response to electroconvulsive therapy (ECT).

METHODS

LTL and mtDNA-cn were measured in 31 TRD patients before (T0), 1 week (T1), and 4 weeks (T2) after the ECT course, as well as in a sample of 65 healthy controls.

RESULTS

TRD patients had significantly shorter LTL and higher mtDNA-cn compared with healthy controls at baseline. In the TRD sample, LTL was inversely correlated with Montgomery-Åsberg Depression Rating Scale scores at baseline. Baseline levels of LTL or mtDNA-cn were not correlated with response to ECT. Similarly, changes in LTL or mtDNA-cn were not associated with response to ECT either when considered as a dichotomous trait (responders vs nonresponders) or as a percentage change in symptoms improvements.

CONCLUSIONS

Ours is the first longitudinal study exploring the role of LTL and mtDNA-cn in response to ECT. Findings of this pilot investigation suggest that LTL and mtDNA-cn may constitute disease biomarkers for TRD but are not involved in response to ECT.

Serum metabolomics after exercise in ambulatory individuals with cerebral palsy

AIM

To evaluate whether serum metabolomics differ between ambulatory individuals with cerebral palsy (CP) compared with individuals with typical development and whether functional capacity is associated with metabolite abundance.

METHOD

Thirty-eight adolescents and young adults were enrolled (CP: n = 19; typical development: n = 19). After functional capacity testing (10-meter walk, sit-to-stand, and peak knee flexion/extension torques), blood was drawn. Targeted serum metabolomics on hydrophilic metabolites were performed by high-performance liquid chromatography coupled with high-resolution and tandem mass spectrometry. Metabolite dimensionality reduction, pathway analysis, fold change, and t-tests evaluated changes in metabolite abundance. Associations were tested between functional measures and metabolite abundance.

RESULTS

Individuals with CP had a significant increase in the abundance of essential amino acids, catabolic products of protein metabolism, and tricarboxylic acid cycle substrates, such as valine, tryptophan, kynurenic acid, and pyruvate (p < 0.05). Importantly, the abundance of numerous metabolites was only highly associated with functional capacity in individuals with CP such that greater abundance was associated with greater capacity, but not in those with typical development.

INTERPRETATION

Our findings show clear increases in serum metabolites in individuals with CP, which are associated with functional capacity for movement. The altered metabolite profile measured after exercise might reflect increased energy production needed for movement. Appropriate nutritional intake during exercise might be needed given increased energy requirements.

Health risks of rare earth elements exposure: Impact on mitochondrial DNA copy number and micronucleus frequency

Toxic effects in terms of mitochondria and hereditary substances have been characterized in vitro for individual rare earth elements, while, the joint effects of mixed elements exposure in the population remain ambiguous. Based on the Occupational Chromate Exposure Dynamic Cohort of China, this study investigated the relationship between 15 blood rare earth elements (cerium, dysprosium, erbium, europium, gadolinium, holmium, lanthanum, lutetium, neodymium, praseodymium, samarium, terbium, thulium, yttrium, and ytterbium) and mitochondrial DNA copy number (MtDNACN) as well as peripheral blood lymphocyte micronucleus frequency (MNF). The elastic net was used to select elements highly correlated with effect indicators, whose dose-response relationships were further illustrated by restricted cubic splines. Bayesian kernel regression was employed to explore the combined effects of elements and the contributions of single element. The results showed that most rare earth elements were positively correlated with effect indicators, with yttrium showing the strongest association (β (95% CI): 0.139 (0.1089 - 0.189) for MtDNACN, 0.937 (0.345 - 1.684) for MNF). In the mixed exposure model, with the exposure level fixed at the 50th percentile as the reference, the effect estimates on MtDNACN and MNF increased by 0.228 and 0.598 units, respectively, at the 75th percentile. The single effect analysis implied that yttrium, lanthanum and terbium contributed the most to the elevation of MtDNACN, while yttrium posed the highest risk for genetic damage, accordingly, we provided recommendations to prioritize these elements of concern. In addition, we observed a chief mediating effect of MtDNACN on the elevation of MNF caused by lanthanum, whereas further mechanistic exploration is required to confirm this finding.

Mitochondrial DNA copy numbers in gastric cancer tissues: a possible biomarker for estimating cancer progression

BACKGROUND

Mitochondria have their own genome (mtDNA), which in humans is a circular multi-copy genome consisting of 16 569 base pairs. Abnormalities in the mtDNA have been reported to correlate with various age-related pathophysiologies.

METHODS

Based on a total of 182 DNA samples extracted from gastric cancer tissues, we measured mtDNA copy numbers (mtDNA-CN) using real-time polymerase chain reaction (PCR) and then examined alongside sex, age, tumor stage, Laurén classification, and the overexpression of Human Epidermal Growth Factor Receptor 2 (HER2).

RESULTS

We found no sex differences in mtDNA-CN and no correlation with age, but significant differences according to tumor stage. The mtDNAcn of intestinal type by Laurén classification was significantly larger than that of diffuse type. There was no significant difference in mtDNA-CN between HER2-positive and -negative tissues. Multiple regression analyses showed that only the tumor stage was a significant variable, while Laurén classification was not.

CONCLUSION

These results indicate that mitochondrial genomic abnormalities contribute the progression of gastric cancer independently of HER2 overexpression, and may shed light on the emerging role of mtDNA-CN in situ as a possible biomarker for estimating cancer progression.

Association of life's essential 8 with leukocyte telomere length and mitochondrial DNA copy number: Findings from the population-based UK Biobank study

OBJECTIVES

To explore the association of Life's Essential 8 (LE8) levels with leukocyte telomere length (LTL) and mitochondrial DNA copy number (mtDNA-CN).

DESIGN

A cross-sectional study.

SETTING AND PARTICIPANTS

225,692 participants aged 37-73 year from the UK Biobank cohort enrolled from 2006 to 2010.

MEASUREMENTS

The LE8 score (0-100) was divided into low (<50), moderate (50-79), and high cardiovascular health (CVH) (≥80) categories, based on health behaviors and factors defined by the American Heart Association. LTL was measured by a validated quantitative polymerase chain reaction method. mtDNA-CN was reacted by standardized SNP probe intensities. The association of CVH (as both a continuous and categorical variable) with LTL and mtDNA-CN was examined using multiple linear regression.

RESULTS

Of 225,692 participants, 5.3% had low CVH, 81.2% had moderate CVH, and 13.4% had high CVH. Participants with higher CVH were usually younger, female, better educated, of higher socioeconomic status, and with a lower prevalence of comorbidities. After adjusting for confounders, a higher LE8 score is associated with longer LTL (Beta = 0.075, P < 0.05) and increased mtDNA-CN (Beta = 0.094, P < 0.05). We also observed that this association was evident in the health behavior score (diet, physical activity, nicotine exposure, and sleep) and the health factors score (BMI, non-HDL cholesterol, blood glucose, and blood pressure), with a stronger positive association of health factors with LTL and mtDNA-CN (Beta = 0.019, P < 0.05; Beta = 0.037, P < 0.05).

CONCLUSIONS

Higher CVH is associated with longer LTL and increased mtDNA-CN.

The 4977 Bp Deletion of Mitochondrial DNA as a Potential Trait Marker for Major Depressive Disorder

Background

Major depressive disorder (MDD) is significantly influenced by genetic factors. The present study aims to examine the potential correlation between the 4977 bp deletion of mitochondrial DNA (mtDNA) and MDD.

Methods

The 4977 bp deletion of mtDNA was detected in the peripheral blood of 253 MDD patients and 257 healthy controls, with depression assessed by the Hamilton Depression Rating scale and functioning by the Global Assessment of Function Scale.

Results

MDD patients had a higher incidence of the 4977 bp deletion, unaffected by demographic or clinical factors.

Conclusion

The 4977 bp deletion may be a trait marker for MDD.

Maternal prenatal stress induces sex-dependent changes in tRNA fragment families and cholinergic pathways in newborns

Maternal perceived prenatal stress (PPS) is a known risk factor for diverse developmental impairments in newborns, but the underlying molecular processes are incompletely understood. Here, we report that maternal PPS altered the birth profiles of blood transfer RNA fragments (tRFs), 16-50 nt long non-random cleavage products of tRNAs, in a sex-dependent manner. Importantly, comparing stressed versus control maternal and umbilical cord blood serum presented alterations that were not limited to individual tRFs, but rather reflected selective changes in particular tRF families grouped by their mitochondrial or nuclear genome origin, parental tRNA coded amino acid, and cleavage type. Specifically, tRF families that show stress- and sex-specific effects, revealed shared length and expression patterns which were strongest in the female newborns. Several of these tRFs carry complementary motifs to particular cholinergic mRNAs, suggesting possible translational regulation similar to microRNAs. Compatible with the cholinergic regulation of stress reactions, those "CholinotRFs" achieved an AUC of 95% when classifying female newborns according to maternal PPS. Moreover, we found altered catalytic activity of serum acetylcholinesterase, which was particularly elevated in male newborns, marking a second sex-specific effect. Our findings demonstrate an association of tRF families' patterns with newborns' sex-specific stress response to PPS and may lead to better diagnosis and therapeutic tools for these and other stressors.

Serum Growth Differentiation Factor 15 is Negatively Associated with Leukocyte Telomere Length

BACKGROUND

Telomere length(TL)and mitochondrial DNA copy number(mtDNAcn) are classic biomarker of aging. Recently, growth differentiation factor 15(GDF15) has attracted considerable attention as a vital component in the aging process.

METHODS

The present study aimed to study the relationship between GDF15 and telomere length and mtDNAcn.This was a cross-sectional analysis nested in a longitudinal cohort study conducted in Changping District, Beijing, from 2014 to 2021. Serum GDF15,leukocyte lelomere length(LTL) and mtDNAcn were determined in 802 subjects.LTL and mtDNAcn was quantified by real-time PCR assay. Multivariate linear regression and restricted cubic spline diagram were used for statistical analysis.

RESULTS

Subjects with higher GDF15 were older,had larger waist circumference, higher systolic blood pressure and glycated hemoglobin A1c (HbA1c),shorter LTL and tended to had less mtDNAcn. In correlation analysis, GDF15 was positively correlated with age, while LTL and mtDNAcn were negatively correlated with age.After adjusting for confounding factors,GDF15 was negatively associated with LTL (β = -0.120, 95%CI [-0.197, -0.042], p = 0.003) and the association was linear(p for nonlinear = 0.645), while the negative association between GDF15 and mtDNAcn did not reach significance.In the stratified analyses,the negative associations between GDF15 and LTL were more prominent in women, overweight individuals, or subjects with abnormal glucose tolerance (AGT), but similar results were observed in younger and older subjects.

CONCLUSIONS

This study found a linear negative association between GDF 15 and LTL,which was more prominent in women, overweight or AGT subjects.These results supported that GDF15 might be a reliable biomarker of aging.

Acute Cannabis Administration Transiently Reduces Mitochondrial DNA in Young Adults: Findings from a Secondary Analysis of a Double-Blind, Placebo-Controlled, Randomized Clinical Trial

Background: Cannabis is one of the world's most commonly used substances; however, many questions remain unanswered as to how cannabis impacts the body. Recently, there has been a resurgence of research into the effects of plant-derived cannabinoids on mitochondrial health. In particular, a number of studies implicate mitochondrial-Δ9-tetrahydrocannabinol (Δ9-THC) interactions with altered memory, metabolism, and catalepsy in mice. Although the research in this field is expanding rapidly, there is little known about the effects of cannabis on mitochondria health in human subjects either in acute or chronic term use. Methods: Blood samples were obtained from a double-blind, placebo-controlled, parallel-group randomized clinical trial in which adults who regularly use cannabis (1-4 days/week) aged 19-25 years were randomized 2:1 to receive either an active (12.5% Δ9-THC) cigarette or placebo (<0.01% Δ9-THC) cigarette containing 750 mg of cannabis before driving simulator testing. DNA was extracted from whole blood using commercial spin columns, followed by measurement of mt-ND1, mt-ND4, and β2M using quantitative polymerase chain reaction. One-way repeated measures analysis of variance (ANOVA) followed by Dunnett's multiple comparisons test was used to observe changes in mitochondrial DNA (mtDNA) copy number over time. A two-tailed Pearsons R test was used to assess correlations between mtDNA copy number and cannabinoid levels (Δ9-THC and metabolites) in blood. Results: We found that exposure to active cannabis containing Δ9-THC, as opposed to placebo, was associated with an acute reduction in mitochondrial DNA copy number in whole blood at 15 min and 1 h after smoking. The observed decrease in mtDNA copy number negatively correlated with blood concentrations of 11-hydroxy-Δ9-tetrahydrocannabinol (11-OH-THC) and 11-Nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH), the two primary metabolites of Δ9-THC, but not Δ9-THC itself. Further, the negative correlation between 11-OH THC and THC-COOH concentrations and mtDNA copy number was found in only a subgroup of participants who use cannabis infrequently, suggesting a tolerance effect. Conclusions: These results illuminate mitochondrial alterations attributed to Δ9-THC consumption, which may be mediated by metabolites. These results appear to suggest stronger effects in individuals who consume cannabis less frequently, suggesting some form of tolerance to the effects of Δ9-THC and its metabolites on mtDNA content in whole blood. Keywords: Mitochondria; mtDNA; cannabis; THC; THC metabolites; blood; THC-COOH; 11-OH-THC.

Investigating the impact of mitochondrial DNA: Insights into blood transfusion reactions and mitigation strategies

BACKGROUND AND OBJECTIVES

Although transfusion reactions occur in less than 2% of recipients, they are currently one of the most serious concerns in blood transfusion. Damage-associated molecular patterns (DAMPs) are released from injured, stressed or dead cells, leading to inflammation and immune system activation. One of the recognized DAMPs is mitochondrial DNA (mtDNA). It is found in various blood products, including fresh frozen plasma (FFP), red blood cell units (RBCUs) and platelet concentrates (PCs), and can induce adverse reactions in recipients by stimulating the innate immune system and inflammatory cellular pathways. The aim of this study was to investigate the factors influencing the release of mtDNA in various blood products and its subsequent impact on transfusion reactions.

MATERIALS AND METHODS

In this study, mtDNA, mitochondrial DNA, mtDNA DAMPs, extracellular mtDNA, blood products, blood components and transfusion reactions between 2009 and 2023 were searched in Google Scholar, PubMed and Scopus databases.

RESULTS

This study has demonstrated the presence of mtDNA in the extracellular milieu of various blood products, including PCs, FFP and RBCUs. Understanding the determinants of mtDNA release and its implications for transfusion safety is critical. Strategies aimed at reducing mtDNA release, such as optimizing preparation techniques and donor selection criteria, hold promise for reducing transfusion-related complications.

CONCLUSION

By addressing these factors, healthcare providers can enhance the safety and efficacy of blood transfusion practices, ultimately improving patient outcomes.

Association between mitochondrial DNA copy number and production traits in pigs

Mitochondria are essential organelles in the regulation of cellular energetic metabolism. Mitochondrial DNA copy number (mtDNA_CN) can be used as a proxy for mitochondria number, size, and activity. The aims of our study are to evaluate the effect of mtDNA_CN and mitochondrial haploblocks on production traits in pigs, and to identify the genetic background of this cellular phenotype. We collected performance data of 234 pigs and extracted DNA from skeletal muscle. Whole-genome sequencing data was used to determine mtDNA_CN. We found positive correlations of muscle mtDNA_CN with backfat thickness at 207 d (+0.14; p-value = 0.07) and negative correlations with carcase loin thickness (-0.14; p-value = 0.03). Pigs with mtDNA_CN values below the lower quartile had greater loin thickness (+4.1 mm; p-value = 0.01) and lower backfat thickness (-1.1 mm; p-value = 0.08), which resulted in greater carcase lean percentage (+2.4%; p-value = 0.04), than pigs with mtDNA_CN values above the upper quartile. These results support the hypothesis that a reduction of mitochondrial activity is associated with greater feed efficiency. Higher mtDNA_CN was also positively correlated with higher meat ultimate pH (+0.19; p-value <0.01) but we did not observe significant difference for meat ultimate pH between the two groups with extreme mtDNA_CN. We found no association of the most frequent mitochondrial haploblocks with mtDNA_CN or the production traits, but several genomic regions that harbour potential candidate genes with functions related to mitochondrial biogenesis and homeostasis were associated with mtDNA_CN. These regions provide new insights into the genetic background of this cellular phenotype but it is still uncertain if such associations translate into noticeable effects on the production traits.

Associations between urinary multiple metal concentrations and mitochondrial DNA copy number among occupational workers

BACKGROUND

Mitochondrial DNA copy number (mtDNAcn) is an effective biomarker to evaluate the effects of cationic metals on mtDNA integrity and function. In this study, we explored the relationships between individual and combined urinary metal concentrations and mtDNAcn among workers.

METHODS

Blood mtDNAcn and urinary metal concentrations were quantified in a cohort of 328 participants. Restricted cubic spline (RCS) models were applied to explore potential non-linear association, while generalized linear models (GLMs) were utilized to assess the associations between urinary metal levels and blood mtDNAcn. We further explored the combined effects of multiple metals on mtDNAcn through quantile g-computation (GQC) and Bayesian kernel machine regression (BKMR).

RESULTS

The dose-response relationship between nickel (Ni) and mtDNAcn exhibited an inverted U-shaped pattern. Notably, GLMs revealed significant reductions in mtDNAcn associated with Ni and silver (Ag) in the second quartile. An overall inverse association between urinary metal mixture and mtDNAcn was observed in the BKMR model when urine dilutions were SG-adjusted. Cre-adjusted lead (Pb) was identified as the primary contributor to decreased mtDNAcn, while SG-adjusted lithium (Li) was indicated as the most substantial contribution to mtDNAcn.

CONCLUSIONS

Urinary metal concentrations were associated with decreased mtDNAcn following SG adjustment. Future research should investigate these associations in a larger population with improved calibration techniques.

Mitochondrial DNA Copy Number as a Potential Biomarker for the Severity of Motor Symptoms and Prognosis in Parkinson's Disease

BACKGROUND

Mitochondrial function influences Parkinson's disease (PD) through the accumulation of pathogenic alpha-synuclein, oxidative stress, impaired autophagy, and neuroinflammation. The mitochondrial DNA copy number (mtDNA-CN), representing the number of mitochondrial DNA copies within a cell, serves as an easily assessable proxy for mitochondrial function.

OBJECTIVE

This study aimed to assess the diagnostic and prognostic capabilities of mtDNA-CN in PD.

METHODS

We assessed mtDNA-CN in blood samples using whole genome sequencing from 405 patients with PD and 200 healthy controls (HC). We examined the relationship between mtDNA-CN levels and motor symptom severity in PD, as well as their association with dementia development in patients with early-PD (within 3 years of diagnosis).

RESULTS

mtDNA-CN levels were significantly lower in patients with PD compared with HC (P = 1.1 × 10-5). A negative correlation was discovered between mtDNA-CN level and motor severity in PD (correlation coefficient = -0.20; P = 0.008). Among 210 patients with early-PD, Cox regression analysis demonstrated an association between lower mtDNA-CN levels and a higher risk of developing dementia (hazard ratio [HR] = 0.41, 95% confidence interval: 0.20-0.86, P = 0.02), even after adjusting for age and blood cell count (HR = 0.41, 95% confidence interval: 0.18-0.92, P = 0.03). However, mtDNA-CN levels did not significantly correlate with motor progression in PD.

CONCLUSION

Our findings suggest that blood mtDNA-CN may function as a diagnostic biomarker for PD and a prognostic marker for dementia in patients with PD. © 2025 International Parkinson and Movement Disorder Society.

Fluctuations in circulating cell-free mitochondrial and nuclear DNA copy numbers in blood plasma after anti-tuberculosis drug intake in patients with drug-susceptible tuberculosis

Biomarker research characterising the effect of anti-tuberculosis (TB) chemotherapy on systemic body response is still limited. In this study, we aimed to investigate fluctuations in circulating cell-free mitochondrial DNA (ccf-mtDNA) and circulating cell-free nuclear DNA (ccf-nDNA) copy number (CN) in blood plasma of patients with drug-susceptible TB (DS-TB) and to decipher factors related to these fluctuations. The results showed considerable changes in ccf-mtDNA CN in plasma samples before drug intake and 2 and 6 h afterwards, with high inter patient variability at each time point. Multivariate linear regression revealed that the dynamics of ccf-mtDNA CN was influenced by patients' age, ethambutol pharmacokinetics, and body-mass index (BMI); ethambutol exposure emerged as the most significant factor. Very low ccf-nDNA CN in all three time points with little variation was observed; none factors were strongly associated with ccf-nDNA. In conclusion, our study revealed the effect of anti-TB chemotherapy, age and BMI on acute changes in circulating ccf-mtDNA CN in blood plasma and highlighted the systemic, mitochondria-related effects of ethambutol in patients with TB. Further studies with larger cohorts are needed to understand the biological relevance of ccf-DNA in patients with TB and to validate its application in TB treatment monitoring.

Mitochondrial DNA copy number alterations: Key players in the complexity of glioblastoma (Review)

Renowned as a highly invasive and lethal tumor derived from neural stem cells in the central nervous system, glioblastoma (GBM) exhibits substantial histopathological variation and genomic complexity, which drive its rapid progression and therapeutic resistance. Alterations in mitochondrial DNA (mtDNA) copy number (CN) serve a crucial role in GBM development and progression, affecting various aspects of tumor biology, including energy production, oxidative stress regulation and cellular adaptability. Fluctuations in mtDNA levels, whether elevated or diminished, can impair mitochondrial function, potentially disrupting oxidative phosphorylation and amplifying reactive oxygen species generation, thereby fueling tumor growth and influencing treatment responses. Understanding the mechanisms of mtDNA‑CN variations, and their interplay with genetic and environmental elements in the tumor microenvironment, is essential for advancing diagnostic and therapeutic strategies. Targeting mtDNA alterations could strengthen treatment efficacy, mitigate resistance and ultimately enhance the prognosis of patients with this aggressive brain tumor. The present review summarizes the existing literature on mtDNA alterations, specifically emphasizing variations in mtDNA‑CN and their association with GBM by surveying articles published between 1996 and 2024, sourced from databases such as Scopus, PubMed and Google Scholar. In addition, the review provides a brief overview of mitochondrial genome architecture, knowledge regarding the regulation of mtDNA integrity and CN, and how mitochondria significantly impact GBM tumorigenesis. This review further presents information on therapeutic approaches for restoring mtDNA‑CN that contribute to optimized mitochondrial function and improved health outcomes.

Emerging PFAS Exposure Is More Potent in Altering Childhood Lipid Levels Mediated by Mitochondrial DNA Copy Number

Per- and polyfluoroalkyl substances (PFAS) pose potential health risks to lipid metabolism, but the effects of emerging PFAS alternatives, particularly in children, remain unclear. This cross-sectional study investigated the association between emerging PFAS exposure and lipid levels in 294 Chinese children aged 7-10 years, analyzing blood samples for 14 PFAS and lipid profiles, including triglycerides (TG), total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), apolipoprotein A1 (ApoA1), and apolipoprotein B (ApoB). Exposure to 6:2 Cl-PFESA, PFO4DA, and PFO5DoDA was associated with higher TC, TG, and LDL levels, with PFO4DA increasing the TC by 1.7% and PFO5DoDA increasing the TG by 10.7%. Weighted quantile sum (WQS) regression showed mixed PFAS exposure positively associated with TG (0.08, 95% CI: 0.007, 0.153). PFO4DA had the highest weight for TC (0.468), TG (0.327), LDL (0.57), ApoA1 (0.243), and ApoB (0.466), while PFMOAA had the highest weight for HDL (0.332). Bayesian Kernel Machine Regression (BKMR) analysis confirmed positive associations between the PFAS mixture and TC, TG, LDL, and ApoA1. Mediation analysis revealed that mtDNAcn significantly mediated PFAS exposure's effect on TG levels, explaining 27.2-74.2% of the total effect. These findings highlight the need for regulatory action to address the emerging PFAS risks.

Lower circulating mitochondrial DNA and increased mitokines suggest significant mitochondrial dysfunction in systemic lupus erythematosus with renal involvement

BACKGROUND

SLE is associated with significant morbidity, especially in the case of renal involvement. Mitochondrial dysfunction plays a significant role in SLE and may be assessed by measuring mitochondrial DNA (mtDNA) and cytokines reflecting mitochondrial stress (mitokines). Circulating mtDNA is a promising biomarker in SLE and appears to be reduced in severe SLE. However, measuring circulating mtDNA is challenging and reported methods are heterogenous. Our study aimed at evaluating whole blood mtDNA to nuclear DNA (nucDNA) ratio using droplet-digital PCR and circulating mitokines, growth differentiation factor 15 (GDF-15) and fibroblast growth factor 21 in SLE with and without renal involvement.

METHODS

Cross-sectional study involving 195 patients with SLE and age-matched healthy volunteers (HV) as control. Biomarkers were compared in patients with and without renal involvement (defined by estimated glomerular filtration rate <60 mL/min or proteinuria >0.5 g/day) and in those with active and inactive SLE.

RESULTS

Compared with HV, patients with SLE displayed lower mtDNA/nucDNA ratios, especially in the case of renal involvement. Accordingly, mitokines were increased in patients with SLE with renal involvement. We found no correlation between mtDNA/nucDNA ratio and global disease activity. Mitokine levels, on the other hand, correlated with disease activity, in particular GDF-15 even after adjusting for renal involvement.

CONCLUSION

Our findings suggest that lower whole blood mtDNA/nucDNA ratio, a surrogate marker for mitochondrial dysfunction, reflects renal damage, while GDF-15 may also reflect disease activity in SLE. Further studies are needed to assess the clinical value of these markers as predictors for active lupus nephritis.

Selection Increases Mitonuclear DNA Discordance but Reconciles Incompatibility in African Cattle

Mitochondrial function relies on the coordinated interactions between genes in the mitochondrial DNA and nuclear genomes. Imperfect interactions following mitonuclear incompatibility may lead to reduced fitness. Mitochondrial DNA introgressions across species and populations are common and well documented. Various strategies may be expected to reconcile mitonuclear incompatibility in hybrids or admixed individuals. African admixed cattle (Bos taurus × B. indicus) show sex-biased admixture, with taurine (B. taurus) mitochondrial DNA and a nuclear genome predominantly of humped zebu (B. indicus). Here, we leveraged local ancestry inference approaches to identify the ancestry and distribution patterns of nuclear functional genes associated with the mitochondrial oxidative phosphorylation process in the genomes of African admixed cattle. We show that most of the nuclear genes involved in mitonuclear interactions are under selection and of humped zebu ancestry. Variations in mitochondrial DNA copy number may have contributed to the recovery of optimal mitochondrial function following admixture with the regulation of gene expression, alleviating or nullifying mitochondrial dysfunction. Interestingly, some nuclear mitochondrial genes with enrichment in taurine ancestry may have originated from ancient African aurochs (B. primigenius africanus) introgression. They may have contributed to the local adaptation of African cattle to pathogen burdens. Our study provides further support and new evidence showing that the successful settlement of cattle across the continent was a complex mechanism involving adaptive introgression, mitochondrial DNA copy number variation, regulation of gene expression, and selection of ancestral mitochondria-related genes.

Mitochondrial DNA copy number associated dementia risk by somatic mutations and frailty

Mitochondrial dysfunction is linked to physical impairment and dementia. Mitochondrial DNA copy number (mtDNAcn) from blood may predict cognitive decline and dementia risk, but the effect of somatic mutations or frailty is unknown. We estimated mtDNAcn using fastMitoCalc and microheteroplasmies using mitoCaller, from Whole Genome Sequencing (WGS) data. In 189,566 participants free of dementia at study entry (mean age = 56 ± 8), we examined the association between mtDNAcn and subsequent dementia diagnosis using Cox regression. Cognition was assessed in a subset on average 8.9 years later. We examined the associations between mtDNAcn and cognitive measures using multivariable linear regression, adjusted for demographic factors, mtDNAcn-related parameters, and apolipoprotein E ε4 status. We further stratified by frailty and microheteroplasmies. Over an average follow-up of 13.2 years, 3533 participants developed dementia. Each SD higher mtDNAcn (16) was associated with 4.2% lower all-cause dementia hazard (HR = 0.958, p = 0.030), 6% lower non-AD dementia hazard (HR = 0.933, p = 0.022), and not-AD dementia hazard. The associations between mtDNAcn and all-cause dementia and non-AD dementia were stronger among those who were pre-frail or frail or with higher microheteroplasmies. Higher mtDNAcn was associated with higher DSST scores (p = 0.036) and significant only among those with higher microheteroplasmies or frailty (p = 0.029 and 0.048, respectively). mtDNAcn was also associated with delta TMT and paired associate learning only in pre-frail/frail participants (p = 0.007 and 0.045, respectively). Higher WGS-based mtDNAcn in human blood is associated with lower dementia risk, specifically non-AD dementia, and specific cognitive function. The relationships appear stronger in high somatic mutations or frailty. Future studies are warranted to investigate biological underpinnings.

Individual and joint associations of exposure to per- and polyfluoroalkyl substances with children's mitochondrial DNA copy number, and modified by estimated glomerular filtration rate

BACKGROUND

The association between per- and polyfluoroalkyl substances (PFAS) and mitochondrial DNA copy number (mtDNAcn) in children, and the potential impact of estimated glomerular filtration rate (eGFR) on this association, remains unclear.

METHODS

We conducted a panel study with up to 3 surveys over 3 seasons in Weinan and Guangzhou, China. A total of 284 children aged 4-12 years were available, with 742 measurements of 11 PFAS and mtDNAcn. Linear mixed-effect (LME), quantile g-computation (qgcomp), weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) models were used to investigate the associations of individuals and a mixture of PFAS with mtDNAcn, and the modifying effect of eGFR on these associations.

RESULTS

Legacy PFAS, including perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorooctane sulfonate (PFOS) and emerging PFAS, 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA), were significantly associated with decreased mtDNAcn in a linear dose-response manner (FDR <0.05). The multiple PFAS model showed each doubling increase in PFOA related to a 6.36% (95%CI: -10.22%, -2.34%) decrement in mtDNAcn. Meanwhile, the PFAS mixture was dose-responsive related to decreased mtDNAcn, with PFOA being the largest contributor, followed by PFUnDA and PFNA. Notably, eGFR modified the inverse association between PFOA and mtDNAcn (P-int = 0.039), with a more pronounced decrement in children with an eGFR below the 20th value (101.71 mL/min/1.73m2). In addition, age significantly modified the relationship between PFOA and decreased mtDNAcn (P-int = 0.028), with a stronger association in those aged 7 years or older.

CONCLUSION

Both individual and the mixture of legacy and emerging PFAS exposure were associated with decreased mtDNAcn in children, with PFOA as the main contributor and modification of eGFR.

Mitochondrial DNA copy number is significantly increased in bipolar disorder patients and is correlated with long-term lithium treatment

Mitochondrial dysfunctions have been reported in bipolar disorder (BD), but their role in the etiopathogenesis of BD as well as their implications in modulating response to pharmacological treatments with psychotropic medications have been scarcely explored. Mitochondrial DNA copy number (mtDNA-cn) has been linked to mitochondria functioning, and, despite some degree of inconsistence, previous findings showed that BD patients present significant differences in mtDNA-cn compared to healthy controls. Here we measured mtDNA-cn in a sample of 89 patients with BD and 78 healthy controls (HC). Patients in the BD sample were treated either with lithium (n = 47) and characterized as responders (n = 22) or non-responders (n = 25), or with other mood stabilizers (n = 42). BD patients had larger mtDNA-cn compared to HC (adjusted model: F2=9.832; p = 0.000095; contribution of diagnosis F1= 10.798; p = 0.001). When the BD sample was stratified for treatment exposure, mtDNA-cn was lower in patients treated with lithium compared to those treated with other mood stabilizers (adjusted model: F4=23.770, p = 7.0929E-13; contribution of treatment: F1=54.300, p = 1.55E-10). Moreover mtDNA-cn was higher in patients treated with other mood stabilizers compared to controls and Li-treated BD patients (F3=28.125, p = 1.36E-14; contribution of groups F2=36.156, p = 1.25E-13). Finally, there was no difference in mtDNA-cn levels in lithium responders compared to non-responders and neither between the two diagnostic groups (BD type 1 and 2). Our findings suggest that BD may be associated with mitochondrial dysfunctions, and that exposure to lithium but not to other mood stabilizers may restore these abnormalities, though this does not appear correlated with the clinical efficacy of lithium.

Associations of Prenatal Mercury Exposure and PUFA with Telomere Length and mtDNA Copy Number in 7-Year-Old Children in the Seychelles Child Development Nutrition Cohort 2

BACKGROUND

Telomere length (TL) and mitochondrial DNA copy number (mtDNAcn) variations are linked to age-related diseases and are associated with environmental exposure and nutritional status. Limited data, however, exist on the associations with mercury exposure, particularly early in life.

OBJECTIVE

We examined the association between prenatal mercury (Hg) exposure and TL and mtDNAcn in 1,145 Seychelles children, characterized by a fish-rich diet.

METHODS

Total mercury (THg) was determined in maternal hair at delivery and cord blood. TL and mtDNAcn were determined relative to a single-copy hemoglobin beta gene in the saliva of 7-y-old children. Linear regression models assessed associations between THg and relative TL (rTL) and relative mtDNAcn (rmtDNAcn) while controlling for maternal and cord serum polyunsaturated fatty acid (PUFA) status and sociodemographic factors. Interactions between THg and child sex, PUFA, and telomerase genotypes were evaluated for rTL and rmtDNAcn.

RESULTS

Higher THg concentrations in maternal hair and cord blood were associated with longer rTL [β = 0.009 ; 95% confidence interval (CI): 0.002, 0.016 and β = 0.002 ; 95% CI: 0.001, 0.003, respectively], irrespective of sex, PUFA, or telomerase genotypes. Maternal serum n-6 PUFA and n-6/n-3 ratio were associated with shorter [β = - 0.24 ; 95% CI: - 0.33 , - 0.15 and β = - 0.032 ; 95% CI: - 0.048 , - 0.016 , respectively] and n - 3 PUFA with longer (β = 0.34 ; 95% CI: 0.032, 0.65) rTL. Cord blood n-6 PUFA was associated with longer (β = 0.15 ; 95% CI: 0.050, 0.26) rTL. Further analyses revealed linoleic acid in maternal blood and arachidonic acid in cord blood as the main drivers of the n-6 PUFA associations. No associations were observed for THg and PUFA with rmtDNAcn.

DISCUSSION

Our results indicate that prenatal THg exposure and PUFA status are associated with rTL later in childhood, although not consistently aligned with our initial hypothesis. Subsequent research is needed to confirm this finding, further evaluate the potential confounding of fish intake, and investigate the underlying molecular mechanisms to verify the use of rTL as a true biomarker of THg exposure. https://doi.org/10.1289/EHP14776.

Mitochondrial DNA abundance and circulating metabolomic profiling: Multivariable-adjusted and Mendelian randomization analyses in UK Biobank

BACKGROUND

Low leukocyte mitochondrial DNA (mtDNA) abundance has been associated with a higher risk of atherosclerotic cardiovascular disease, but through unclear mechanisms. We aimed to investigate whether low mtDNA abundance is associated with worse metabolomic profiling, as being potential intermediate phenotypes, using cross-sectional and genetic studies.

METHODS

Among 61,186 unrelated European participants from UK Biobank, we performed multivariable-adjusted linear regression analyses to examine the associations between mtDNA abundance and 168 NMR-based circulating metabolomic measures and nine metabolomic principal components (PCs) that collectively covered 91.5% of the total variation of individual metabolomic measures. Subsequently, we conducted Mendelian randomization (MR) to approximate the causal effects of mtDNA abundance on the individual metabolomic measures and their metabolomic PCs.

RESULTS

After correction for multiple testing, low mtDNA abundance was associated with 130 metabolomic measures, predominantly lower concentrations of some amino acids and higher concentrations of lipids, lipoproteins and fatty acids; moreover, mtDNA abundance was associated with seven out of the nine metabolomic PCs. Using MR, genetically-predicted low mtDNA abundance was associated with lower lactate (standardized beta and 95% confidence interval: -0.17; -0.26, -0.08), and higher acetate (0.15; 0.07,0.23), and unsaturation degree (0.14; 0.08,0.20). Similarly, genetically-predicted low mtDNA abundance was associated with lower metabolomic PC2 (related to lower concentrations of lipids and fatty acids), and higher metabolomic PC9 (related to lower concentrations of glycolysis-related metabolites).

CONCLUSION

Low mtDNA abundance is associated with metabolomic perturbations, particularly reflecting a pro-atherogenic metabolomic profile, which potentially could link low mtDNA abundance to higher atherosclerosis risk.

Mitochondrial DNA (mtDNA) as fluid biomarker in neurodegenerative disorders: A systematic review

BACKGROUND

Several studies evaluated peripheral and cerebrospinal fluid (CSF) mtDNA as a putative biomarker in neurodegenerative diseases, often yielding inconsistent findings. We systematically reviewed the current evidence assessing blood and CSF mtDNA levels and variant burden in Parkinson's disease (PD), Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS). Multiple sclerosis (MS) was also included as a paradigm of chronic neuroinflammation-driven neurodegeneration.

METHODS

Medline, Embase, Scopus and Web of Science were searched for articles published from inception until October 2023. Studies focused on mtDNA haplogroups or hereditary pathogenic variants were excluded. Critical appraisal was performed using the Quality Assessment for Diagnostic Accuracy Studies criteria.

RESULTS

Fifty-nine original studies met our a priori-defined inclusion criteria. The majority of CSF-focused studies showed (i) decreased mtDNA levels in PD and AD; (ii) increased levels in MS compared to controls. No studies evaluated CSF mtDNA in ALS. Results focused on blood cell-free and intracellular mtDNA were contradictory, even within studies evaluating the same disease. This poor reproducibility is likely due to the lack of consideration of the many factors known to affect mtDNA levels. mtDNA damage and methylation levels were increased and reduced in patients compared to controls, respectively. A few studies investigated the correlation between mtDNA and disease severity, with conflicting results.

CONCLUSIONS

Additional well-designed studies are needed to evaluate CSF and blood mtDNA profiles as putative biomarkers in neurodegenerative diseases. The identification of "mitochondrial subtypes" of disease may enable novel precision medicine strategies to counteract neurodegeneration.

A Review over Mitochondrial Diseases Due to mtDNA Mutations: Recent Advances and Remedial Aspects

Mitochondria, also called 'powerhouse of the cell', is meant for energy generation in eukaryotic cells. This action is performed by mitochondria through the oxidative phosphorylation (OXPHOS) of the respiratory chain (RC). Based on the functioning of the cell, the number of mitochondria varies up to thousands in number. Mutations in the mitochondrial DNA (mtDNA) and/or nuclear DNA (nDNA) genes may lead to the generation of primary mitochondrial disease (PMD) that affects the structure and function of mitochondria. The diagnosis of such mitochondrial diseases occurs in early childhood and it can lead to serious, fetal and multi-organ diseases. Understanding epigenetic events and changes in the pathway can help improve the effectiveness of treatment. However, there are several reasons lack of the disease symptoms (age, sign, symptoms, morbidity and lethality), restricted availability of preclinical models along with extensive phenotypes that hamper the development of efficient drugs. Despite the introduction of new treatments and the encouraging results of treatments and therapies, there is no effective cure for PMD. This article contains information about the changes associated with cytopathic diseases that make possible the analysis of various diseases by genetic techniques. Increasing our understanding of how mitochondrial DNA mutations affect mitochondrial metabolism and subsequently result in neurodegenerative disease will prove vital to the development of targeted therapies and treatments.

Reduction in mitochondrial DNA methylation leads to compensatory increase in mitochondrial DNA content: novel blood-borne biomarkers for monitoring occupational noise

BACKGROUND

Prolonged occupational noise exposure poses potential health risks, but its impact on mitochondrial DNA (mtDNA) damage and methylation patterns remains unclear.

METHOD

We recruited 306 factory workers, using average binaural high-frequency hearing thresholds from pure-tone audiometry to assess noise exposure. MtDNA damage was evaluated through mitochondrial DNA copy number (mtDNAcn) and lesion rate, and mtDNA methylation changes were identified via pyrophosphate sequencing.

RESULTS

There was a reduction in MT-RNR1 methylation of 4.52% (95% CI: -7.43% to -1.62%) among workers with abnormal hearing, whereas changes in the D-loop region were not statistically significant (β = -2.06%, 95% CI: -4.44% to 0.31%). MtDNAcn showed a negative association with MT-RNR1 methylation (β = -0.95, 95% CI: -1.23 to -0.66), while no significant link was found with D-loop methylation (β = -0.05, 95% CI: -0.58 to 0.48). Mediation analysis indicated a significant increase in mtDNAcn by 10.75 units (95% CI: 3.00 to 21.26) in those with abnormal hearing, with MT-RNR1 methylation mediating 35.9% of this effect.

CONCLUSIONS

These findings suggest that occupational noise exposure may influence compensatory increases in mtDNA content through altered MT-RNR1 methylation.

Mitochondrial DNA copy number and risk of cardiovascular disease and all-cause mortality: a systematic review and meta-analysis of observational studies

Increasing studies have explored the correlation of mitochondrial DNA copy number (mtDNA-CN) abnormalities with cardiovascular disease (CVD) and all-cause mortality; however, their findings are contradictory. This systematic review and meta-analysis sought to quantitatively summarize current studies to elucidate the impact of mtDNA-CN on CVD outcomes and all-cause mortality. Relevant studies were searched for in PubMed, Embase and Web of Science databases, up to 23 October 2023. Summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated with the random-effects model. In total, 22 articles were included in the systematic review, 13 of which were included in the meta-analysis of CVD outcomes and 8 in all-cause mortality. Compared to the highest mtDNA-CN level, the summary RR (95% CI) for the lowest mtDNA-CN level was 2.09 (95% CI 1.59-2.75) for CVD, 1.70 (95% CI 1.29-2.24) for coronary heart disease (CHD), 1.43 (95% CI 1.15-1.79) for heart failure (HF), 1.88 (95% CI 1.08-3.28) for stroke and 1.33 (95% CI 1.21-1.47) for all-cause mortality. Lower mtDNA-CN may increase the risk of CVD, including CHD, HF and stroke, as well as all-cause mortality. MtDNA-CN is a potential predictor of CVD and all-cause mortality.

Mitochondria at the crossroad of dysregulated inflammatory and metabolic processes in bipolar disorders

In last few decades, considerable evidence has emphasized the significant involvement of mitochondria, often referred to as the "powerhouse of the cell," in the pathophysiology of bipolar disorder (BD). Given crucial mitochondrial functions in cellular metabolism and inflammation, both of which are compromised in BD, this perspective review examines the central role of mitochondria in inflammation and metabolism within the context of this disorder. We first describe the significance of mitochondria in metabolism before presenting the dysregulated inflammatory and metabolic processes. Then, we present a synthetic and hypothetical model of the importance of mitochondria in those dysfunctional pathways. The article also reviews different techniques for assessing mitochondrial function and discuss diagnostic and therapeutic implications. This review aims to improve the understanding of the inflammatory and metabolic comorbidities associated with bipolar disorders along with mitochondrial alterations within this context.

White Matter Imaging Phenotypes Mediate the Negative Causality of Mitochondrial DNA Copy Number on Sleep Apnea: A Bidirectional Mendelian Randomization Study and Mediation Analysis

Purpose

Sleep apnea (SA), associated with absent neural output, is characterised by recurrent episodes of hypoxemia and repeated arousals during sleep, resulting in decreased sleep quality and various health complications. Mitochondrial DNA copy number (mtDNA-CN), an easily accessible biomarker in blood, reflects mitochondrial function. However, the causal relationship between mtDNA-CN and SA remains unclear. This study aimed to investigate the causality between mtDNA-CN and SA while identifying potential mediating brain imaging phenotypes (BIPs).

Methods

Two-sample bidirectional Mendelian randomisation (MR) analysis was performed to estimate the causal relationship between mtDNA-CN and SA, with further validation using Bayesian framework-based MR analysis. A two-step approach was employed to evaluate causal relationships between BIPs, mtDNA-CN and SA, utilising the "product of coefficients" method to assess the mediating effects of BIPs. Multiple testing errors were corrected using the Benjamini-Hochberg method.

Results

Genetically predicted mtDNA-CN had a negative causal effect on SA (OR = 0.859, 95% CI = 0.785-0.939, P = 3.20×10-4), whereas SA did not have a causal effect on mtDNA-CN (OR = 1.0056, 95% CI = 0.9954-1.0159, P = 0.2825). Among 3935 BIPs, two features related to white matter microstructure served as partial mediators: the second eigenvalue from diffusion MRI data analysed by tract-based spatial statistics in the right posterior thalamic radiation, with a mediation proportion of 11.37% (P = 0.0450), and fractional anisotropy in the right sagittal stratum, with a mediation proportion of 12.79% (P = 0.0323).

Conclusion

This study demonstrated a causal relationship between mtDNA-CN and SA, with specific brain white matter microstructure phenotypes potentially acting as mediators. These findings highlight the potential of mtDNA-CN as a biomarker for SA and underscore its relevance in guiding future therapeutic strategies targeting mitochondrial health and brain white matter microstructure.

The mitochondrial function of peripheral blood cells in cognitive frailty patients

Background

Cognitive frailty (CF), characterized by the coexistence of physical frailty and cognitive impairment, is linked to increased morbidity and mortality in older adults. While CF has been linked to multiple physiological and lifestyle factors, the underlying biological mechanisms remain poorly understood. This study investigated the risk factors for CF and explored the relationship between mitochondrial function and CF in hospitalized patients.

Methods

A total of 279 hospitalized individuals were recruited from December 2020 to August 2022, conducted comprehensive clinical assessments, and collected peripheral blood samples. CF was evaluated using the Physical Frailty Phenotype and Montreal Cognitive Assessment scales. Nutritional status was assessed with the Mini Nutritional Assessment, and depression was measured using the Geriatric Depression Scale. DNA was obtained from the peripheral blood and interrogated for mitochondrial DNA copy number (mtDNAcn). Peripheral blood mononuclear cells isolated from peripheral blood were examined for respiratory function and reactive oxygen species (ROS) levels. Additionally, plasma samples were analyzed for inflammatory markers and Carnitine Palmitoyltransferase II (CPT2).

Results

Among the participants, 90 were classified as CF and 46 as non-CF. Logistic regression analysis revealed that increased age (OR 1.156, 95% CI 1.064-1.255), lower educational attainment (OR 0.115, 95% CI 0.024-0.550), malnutrition (OR 0.713, 95% CI 0.522-0.973), and higher depression scores (OR 1.345, 95% CI 1.065-1.699) were significantly associated with CF. The independent t tests and Mann-Whitney U tests showed the CF group exhibited impaired mitochondrial function, characterized by reduced mtDNAcn and respiratory activity, coupled with elevated ROS, interleukin-6, and CPT2 levels compared with the non-CF group. After adjusted for age, sex, and BMI, compared with non-CF group, the OR values for the CF group of mtDNAcn and ROS were 0.234 (95% CI = 0.065-0.849) (p = 0.027) and 1.203 (95% CI = 1.075-1.347) (p = 0.001), respectively. The Sensitive analysis showed that the area under curve values for mtDNAcn and ROS were 0.653 and 0.925.

Conclusion

Age, lower educational attainment, malnutrition, and depression are significant risk factors for CF. Moreover, mitochondrial dysfunction, characterized by decreased mtDNAcn, impaired respiratory function and increased ROS levels appears to be a critical phenotype of CF.

Mitochondrial DNA copy number and the risk of autoimmune diseases: A Mendelian randomization study with meta-analysis

Background

Mitochondrial DNA plays a crucial role in the pathophysiology of autoimmune diseases (ADs). However, the association between mitochondrial DNA copy number (mtDNA-CN) and ADs risk is controversial. In this study, Mendelian randomization (MR) analysis and meta-analysis were performed using three sets of independent instrumental variables (IVs) to investigate the potential association between mtDNA-CN and 20 types of ADs.

Methods

The three sets of IVs were drawn primarily from participants in the UK Biobank and the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium using different methods. Outcome data for ADs were investigated using summary statistics from the FinnGen cohort. The potential causal associations were assessed using inverse-variance weighting (IVW), MR-Egger, and weighted median methods. Sensitivity analysis and the Steiger test were used to verify the robustness of the MR estimates. In addition, a meta-analysis was conducted to pool the results from three IV groups.

Results

Overall, genetically predicted mtDNA-CN was not associated with ADs risk (OR = 1.046, 95 % CI: 0.964-1.135, P = 0.283). However, subgroup analyses showed positive causal associations of mtDNA-CN with autoimmune hypothyroidism (OR = 1.133, 95 % CI: 1.016-1.262, P = 0.024) and rheumatoid arthritis (OR = 1.219, 95 % CI: 1.028-1.445, P = 0.023). In contrast, there was no causal association between mtDNA-CN and atopic dermatitis as well as psoriasis, ulcerative colitis, adult-onset Still disease, type1 diabetes, Crohn disease, sarcoidosis, ankylosing spondylitis, multiple sclerosis, autoimmune hyperthyroidism, primary sclerosing cholangitis, systemic lupus erythematosus, systemic sclerosis, alopecia areata, myasthenia gravis, Guillain-Barre syndrome, dermatopolymyositis, and vitiligo.

Conclusions

This MR analysis showed mtDNA-CN is causally associated with an increased risk of autoimmune hypothyroidism and rheumatoid arthritis at the genetic level. The findings have important implications for the use of mtDNA-CN as a biomarker for risk assessment of autoimmune hypothyroidism and rheumatoid arthritis in clinical practice.

Global DNA methylation is not elevated in blood samples from Machado-Joseph disease mutation carriers

Machado-Joseph disease (MJD) is an autosomal dominant spinocerebellar ataxia (SCA) caused by a polyglutamine expansion in the ataxin-3 protein, which initiates a cascade of pathogenic events, including transcriptional dysregulation. Genotype-phenotype correlations in MJD are incomplete, suggesting an influence of additional factors, such as epigenetic modifications, underlying the MJD pathogenesis. DNA methylation is known to impact the pathophysiology of neurodegenerative disorders through gene expression regulation and increased methylation has been reported for other SCAs. In this work we aimed to analyse global methylation in MJD carriers. Global 5-mC levels were quantified in blood samples of 33 MJD mutation carriers (patients and preclinical subjects) and 33 healthy controls, matched by age, sex, and smoking status. For a subset of 16 MJD subjects, a pilot follow-up analysis with two time points was also conducted. No differences were found in median global 5-mC levels between MJD mutation carriers and controls and no correlations between methylation levels and clinical or genetic variables were detected. Also, no alterations in global 5-mC levels were observed over time. Our findings do not support an increase in global blood methylation levels associated with MJD.

Mitochondrial Health Markers and Obesity-Related Health in Human Population Studies: A Narrative Review of Recent Literature

PURPOSE OF REVIEW

This narrative review summarizes current literature on the relationship of mitochondrial biomarkers with obesity-related characteristics, including body mass index and body composition.

RECENT FINDINGS

Mitochondria, as cellular powerhouses, play a pivotal role in energy production and the regulation of metabolic process. Altered mitochondrial functions contribute to obesity, yet evidence of the intricate relationship between mitochondrial dynamics and obesity-related outcomes in human population studies is scarce and warrants further attention. We discuss emerging evidence linking obesity and related health outcomes to impaired oxidative phosphorylation pathways, oxidative stress and mtDNA variants, copy number and methylation, all hallmark of suboptimal mitochondrial function. We also explore the influence of dietary interventions and metabolic and bariatric surgery procedures on restoring mitochondrial attributes of individuals with obesity. Finally, we report on the potential knowledge gaps in the mitochondrial dynamics for human health for future study.

scMitoMut for calling mitochondrial lineage-related mutations in single cells

Tracing cell lineages has become a valuable tool for studying biological processes. Among the available tools for human data, mitochondrial DNA (mtDNA) has a high potential due to its ability to be used in conjunction with single-cell chromatin accessibility data, giving access to the cell phenotype. Nonetheless, the existing mutation calling tools are ill-equipped to deal with the polyploid nature of the mtDNA and lack a robust statistical framework. Here we introduce scMitoMut, an innovative R package that leverages statistical methodologies to accurately identify mitochondrial lineage-related mutations at the single-cell level. scMitoMut assigns a mutation quality q-value based on beta-binomial distribution to each mutation at each locus within individual cells, ensuring higher sensitivity and precision of lineage-related mutation calling in comparison to current methodologies. We tested scMitoMut using single-cell DNA sequencing, single-cell transposase-accessible chromatin (scATAC) sequencing, and 10× Genomics single-cell multiome datasets. Using a single-cell DNA sequencing dataset from a mixed population of cell lines, scMitoMut demonstrated superior sensitivity in identifying a small proportion of cancer cell line compared to existing methods. In a human colorectal cancer scATAC dataset, scMitoMut identified more mutations than state-of-the-art methods. Applied to 10× Genomics multiome datasets, scMitoMut effectively measured the lineage distance in cells from blood or brain tissues. Thus, the scMitoMut is a freely available, and well-engineered toolkit (https://www.bioconductor.org/packages/devel/bioc/html/scMitoMut.html) for mtDNA mutation calling with high memory and computational efficiency. Consequently, it will significantly advance the application of single-cell sequencing, facilitating the precise delineation of mitochondrial mutations for lineage-tracing purposes in development, tumour, and stem cell biology.

Peripheral immune cell abundance differences link blood mitochondrial DNA copy number and Parkinson's disease

Mitochondrial dysfunction plays an important role in Parkinson's disease (PD), with mitochondrial DNA copy number (mtDNA-CN) emerging as a potential marker for mitochondrial health. We investigated the links between blood mtDNA-CN and PD severity and risk using the Accelerating Medicines Partnership program for Parkinson's Disease dataset, replicating our results in the UK Biobank. Our findings reveal that reduced blood mtDNA-CN levels are associated with heightened PD risk and increased severity of motor symptoms and olfactory dysfunction. We estimated blood cell composition using complete blood cell profile when available or RNA-sequencing data as a surrogate. After adjusting for blood cell composition, the associations between mtDNA-CN and PD risk and clinical symptoms became non-significant. Bidirectional Mendelian randomization analysis also found no evidence of a direct causal relationship between blood mtDNA-CN and PD susceptibility. Hence peripheral inflammatory immune responses rather than mitochondrial dysfunction underpin these previously identified associations in PD.

Inference of forensic body fluids/tissues based on mitochondrial DNA copy number: a preliminary study

The inference of body fluids and tissues is critical in reconstructing crime scenes and inferring criminal behaviors. Nevertheless, present methods are incompatible with conventional DNA genotyping, and additional testing might result in excessive consumption of forensic scene materials. This study aims to investigate the feasibility of distinguishing common body fluids/tissues through the difference in mitochondrial DNA copy number (mtDNAcn). Four types of body fluids/tissues were analyzed in this study - hair, saliva, semen, and skeletal muscle. MtDNAcn was estimated by dividing the read counts of mitochondrial DNA to that of nuclear DNA (RRmt/nu). Results indicated that there were significant differences in RRmt/nu between different body fluids/tissues. Specifically, hair samples exhibited the highest RRmt/nu (log10RRmt/nu: 4.3 ± 0.28), while semen samples showed the lowest RRmt/nu (log10RRmt/nu: -0.1 ± 0.28). RRmt/nu values for DNA samples without extraction were notably higher (approximately 2.9 times) than those obtained after extraction. However, no significant difference in RRmt/nu was observed between various age and gender groups. Hierarchical clustering and Kmeans clustering analyses showed that body fluids/tissues of the same type clustered closely to each other and could be inferred with high accuracy. In conclusion, this study demonstrated that the simultaneous detection of nuclear and mitochondrial DNA made it possible to perform conventional DNA analyses and body fluid/tissue inference at the same time, thus killing two birds with one stone. Furthermore, mtDNAcn has the potential to serve as a novel and promising biomarker for the identification of body fluids/tissues.

Hexavalent chromium exposure induces lung injury via activation of NLRP3 and AIM2 inflammasomes in rats

Hexavalent chromium (Cr(VI)) has been identified as a Class I human carcinogen, but its carcinogenic mechanism is currently unclear. There is still a lack of understanding of its associations with early pulmonary inflammatory damages. Inflammation is an important stage before the occurrence of tumors, and under the long-term stimulation of inflammation, it can promote the development of tumors. In this study, the aim is to explore the effect of Cr(VI) exposure on pulmonary inflammation and its relationship with the mechanism of inflammation cancer transformation. We established a Cr(VI) exposure model in SD rats using tracheal instillation of potassium dichromate solution, and collected samples at the time of cessation of exposure and 14 days after cessation of exposure. Analyzing the experimental results, it was found that the lung index increased after exposure to Cr(VI), promoting the occurrence of apoptosis in lung tissue cells and exacerbating lung tissue damage. The damage situation improved after exposure termination; Inductively coupled plasma mass (ICPRQ) spectrometer detection found that the exposed group had significantly increased levels of blood chromium, blood manganese, blood copper, blood arsenic, urine chromium, urine copper, and urine lead; After two weeks of repair, blood chromium and blood manganese levels were significantly lower than those in the same dose group of the exposure group, while blood copper levels were significantly higher than those in the same dose group of the exposure group. There was no significant difference in blood arsenic levels between the exposure group and the exposure group. Urine chromium and urine lead levels were significantly lower than those in the same dose group of the exposure group, while urine copper levels only increased. At the same time, it was found that Cr(VI) exposure caused disruption of oxidative stress levels in rat lung tissues. After 14-day exposure, Cr(VI) significantly decreased and oxidative stress levels significantly decreased. Further investigation revealed that Cr(VI) induces activation of inflammasomes NLRP3, AIM2, and their signaling pathways in lung inflammatory injuries, but this condition persists even after cessation of exposure. The study suggested that in hexavalent chromium induced lung tissue injuries in rats, NLRP3 and AIM2 inflammasomes and their signaling pathways activation. Furthermore, the characteristic of sustained activation after cessation of exposure was also indicated. These results provide new ideas and references for further elucidating the mechanisms of Cr(VI), lung inflammation and inflammation cancer transformation.

Blood-derived mitochondrial DNA copy number is associated with Alzheimer disease, Alzheimer-related biomarkers and serum metabolites

BACKGROUND

Blood-derived mitochondrial DNA copy number (mtDNA-CN) is a proxy measurement of mitochondrial function in the peripheral and central systems. Abnormal mtDNA-CN not only indicates impaired mtDNA replication and transcription machinery but also dysregulated biological processes such as energy and lipid metabolism. However, the relationship between mtDNA-CN and Alzheimer disease (AD) is unclear.

METHODS

We performed two-sample Mendelian randomization (MR) using publicly available summary statistics from GWAS for mtDNA-CN and AD to investigate the causal relationship between mtDNA-CN and AD. We estimated mtDNA-CN using whole-genome sequence data from blood and brain samples of 13,799 individuals from the Alzheimer's Disease Sequencing Project. Linear and Cox proportional hazards models adjusting for age, sex, and study phase were used to assess the association of mtDNA-CN with AD. The association of AD biomarkers and serum metabolites with mtDNA-CN in blood was evaluated in Alzheimer's Disease Neuroimaging Initiative using linear regression. We conducted a causal mediation analysis to test the natural indirect effects of mtDNA-CN change on AD risk through the significantly associated biomarkers and metabolites.

RESULTS

MR analysis suggested a causal relationship between decreased blood-derived mtDNA-CN and increased risk of AD (OR = 0.68; P = 0.013). Survival analysis showed that decreased mtDNA-CN was significantly associated with higher risk of conversion from mild cognitive impairment to AD (HR = 0.80; P = 0.002). We also identified significant associations of mtDNA-CN with brain FDG-PET (β = 0.103; P = 0.022), amyloid-PET (β = 0.117; P = 0.034), CSF amyloid-β (Aβ) 42/40 (β=-0.124; P = 0.017), CSF t-Tau (β = 0.128; P = 0.015), p-Tau (β = 0.140; P = 0.008), and plasma NFL (β=-0.124; P = 0.004) in females. Several lipid species, amino acids, biogenic amines in serum were also significantly associated with mtDNA-CN. Causal mediation analyses showed that about a third of the effect of mtDNA-CN on AD risk was mediated by plasma NFL (P = 0.009), and this effect was more significant in females (P < 0.005).

CONCLUSIONS

Our study indicates that mtDNA-CN measured in blood is predictive of AD and is associated with AD biomarkers including plasma NFL particularly in females. Further, we illustrate that decreased mtDNA-CN possibly increases AD risk through dysregulation of mitochondrial lipid metabolism and inflammation.

Mitochondrial DNA copy number and neurocognitive outcomes in children

BACKGROUND

Low mitochondria DNA copy number (mtDNAcn) has been linked to cognitive decline. However, the role of mtDNAcn in healthy cognitive development is unclear. We hypothesized early-life mtDNAcn would be associated with children's learning and memory.

METHODS

We quantified mtDNAcn in umbilical cord blood and child blood at ages 5-7 from participants in a prospective birth cohort. We administered the Children's Memory Scale (CMS) at ages 9-14 (N = 342) and the Wechsler Intelligence Scale for Children (WISC-IV) at ages 7 and 9 (N = 457). Associations between mtDNAcn tertiles and CMS and WISC were evaluated with linear regression and linear mixed-effects models, respectively. We examined non-linear associations using generalized additive mixed models.

RESULTS

Relative to the middle tertile of mtDNAcn, lower childhood mtDNAcn was associated with lower WISC Working Memory (β = -2.65, 95% CI [-5.24, -0.06]) and Full-Scale IQ (β = -3.71 [-6.42, -1.00]), and higher CMS Visual Memory (β = 4.70 [0.47, 8.93]). Higher childhood mtDNAcn was linked to higher CMS Verbal Memory (β = 7.75 [2.50, 13.01]). In non-linear models, higher childhood mtDNAcn was associated with lower WISC Verbal Comprehension.

CONCLUSIONS

Our study provides novel evidence that mtDNAcn measured in childhood is associated with children's neurocognitive performance. mtDNAcn may be a marker of healthy child development.

IMPACT

Mitochondrial DNA copy number (mtDNAcn) may serve as a biomarker for early-life neurocognitive performances in the children's population. Both low and high mtDNAcn may contribute to poorer neurocognition, reflected through learning and memory abilities. This research elucidated the importance of investigating mitochondrial biomarkers in healthy populations and facilitated advancements of future studies to better understand the associations between mitochondrial markers and adverse children's health outcomes.

Platelet dysfunction caused by differentially expressed genes as key pathogenic mechanisms in COVID-19

At the end of 2019, the novel coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) became prevalent worldwide, which brought a heavy medical burden and tremendous economic losses to the world population. In addition to the common clinical respiratory symptoms such as fever, cough and headache, patients with COVID-19 often have hematological diseases, especially platelet dysfunction. Platelet dysfunction usually leads to multiple organ dysfunction, which is closely related to patient severity or mortality. In addition, studies have confirmed significant changes in the gene expression profile of circulating platelets under SARS-CoV-2 infection, which will further lead to changes in platelet function. At the same time, studies have shown that platelets may absorb SARS-COV-2 mRNA independently of ACE2, which further emphasizes the importance of the stability of platelet function in defense against SARS-CoV-2 infection. This study reviewed the relationship between COVID-19 and platelet and SARS-CoV-2 damage to the circulatory system, and further analyzed the significantly differentially expressed mRNA in platelets after infection with SARS-CoV-2 on the basis of previous studies. The top eight hub genes were identified as NLRP3, MT-CO1, CD86, ICAM1, MT-CYB, CASP8, CXCL8 and CXCR4. Subsequently, the effects of SARS-CoV-2 infection on platelet transcript abnormalities and platelet dysfunction were further explored on the basis of 8 hub genes. Finally, the treatment measures of complications caused by platelet dysfunction in patients with COVID-19 were discussed in detail, so as to provide reference for the prevention, diagnosis and treatment of COVID-19.

Mitochondrial genetic variations in leukemia: a comprehensive overview

Leukemias are a group of heterogeneous hematological malignancies driven by diverse genetic variations, and the advent of genomic sequencing technologies facilitates the investigation of genetic abnormalities in leukemia. However, these sequencing-based studies mainly focus on nuclear DNAs. Increasing evidence indicates that mitochondrial dysfunction is an important mechanism of leukemia pathogenesis, which is closely related to the mitochondrial genome variations. Here, we provide an overview of current research progress concerning mitochondrial genetic variations in leukemia, encompassing gene mutations and copy number variations. We also summarize currently accessible mitochondrial DNA (mtDNA) sequencing methods. Notably, somatic mtDNA mutations may serve as natural genetic barcodes for lineage tracing and longitudinal assessment of clonal dynamics. Collectively, these findings enhance our understanding of leukemia pathogenesis and foster the identification of novel therapeutic targets and interventions.

The researcher's guide to selecting biomarkers in mental health studies

Clinical mental health researchers may understandably struggle with how to incorporate biological assessments in clinical research. The options are numerous and are described in a vast and complex body of literature. Here we provide guidelines to assist mental health researchers seeking to include biological measures in their studies. Apart from a focus on behavioral outcomes as measured via interviews or questionnaires, we advocate for a focus on biological pathways in clinical trials and epidemiological studies that may help clarify pathophysiology and mechanisms of action, delineate biological subgroups of participants, mediate treatment effects, and inform personalized treatment strategies. With this paper we aim to bridge the gap between clinical and biological mental health research by (1) discussing the clinical relevance, measurement reliability, and feasibility of relevant peripheral biomarkers; (2) addressing five types of biological tissues, namely blood, saliva, urine, stool and hair; and (3) providing information on how to control sources of measurement variability.

Leukocyte mitochondrial DNA copy number and cardiovascular disease: A systematic review and meta-analysis of cohort studies

Increasing cohort studies have examined the link between mitochondrial DNA copy number (mtDNA-CN) and cardiovascular disease (CVD), with inconsistent findings. We searched PubMed, EMBASE, and Web of Science up to July 11, 2023 and used a random-effects model to calculate summary hazard ratios (HRs) and 95% confidence intervals (CIs). This systematic review and meta-analysis included 8 articles encompassing 29 studies with 646,398 participants. Individuals with the lowest mtDNA-CN had a summary HR of 1.27 (95% CI 1.02-1.59) for CVD, 1.18 (95% CI 0.92-1.50) for coronary heart disease (CHD), 1.10 (95% CI 0.89-1.37) for stroke, and 1.30 (95% CI 1.07-1.56) for heart failure (HF). Decreased mtDNA-CN is linked to an increased risk of CVD and HF but not CHD and stroke. These findings suggest mtDNA-CN from leukocytes may be a potential early biomarker for CVD. However, more prospective studies with long follow-up are needed.

Association between mitochondrial DNA copy number and neurodevelopmental outcomes among black and white preterm infants up to two years of age

Objectives

Mitochondrial DNA copy number (mtDNAcn) is associated with mitochondrial function, with abnormal copy numbers having been linked to various disease states. Our study aims to understand the association between infant mtDNAcn and infant neurodevelopment, as well as the association with racial disparities.

Methods

A longitudinal study was conducted with 55 preterm infants from whom a single blood sample was collected during their Neonatal intensive care unit (NICU) stay and used to analyze mtDNAcn. In addition, the NICU Network Neurobehavioral Scale at 36-38 postmenstrual age (PMA) and the Bayley Scale of Infant and Toddler Development (Bayley) Edition III at 1 and 2 years of corrected age were both conducted. Linear regression models were performed to investigate the relationship between infant clinical characteristics, infant neurobehavioral outcomes, and mtDNAcn.

Results

The majority of infants studied were white (72.73%), non-Hispanic (70.91%), males (54.55%), delivered through C-section (72.73%), and without preterm premature rupture of membrane (76.36%). Increased mtDNAcn was associated with younger birth gestational age (<30.57 wk, P < 0.001). In addition, the opposite associations between mtDNAcn and neurodevelopmental outcomes were observed between white and black infants up to 1 year of gestational age.

Conclusions

Increased mtDNAcn in white infants, and decreased mtDNAcn in black infants may be considered significant predictors of poor early-life neurodevelopmental outcomes in infants. A better understanding of the underlying mechanisms contributing to infant disparity in mtDNAcn and how low or high copy number impacts infant outcomes is essential.

Mitochondria-DNA copy-number in osteoporosis and osteoarthritis among middle-aged women - A population-based cohort study

Background

Mitochondrial DNA copy number (mtDNA-CN) is associated with aging. A relationship between mtDNA-CN and degenerative disorders, e.g. osteoarthritis (OA) and osteoporosis (OP), has been suggested. We aimed to investigate the relationship of mtDNA-CN and incident OA and OP.

Materials and methods

MtDNA-CN was studied in relationship to incident OA and OP in a population-based cohort study of 6916 middle-aged women (52-63 years). Totally 2521 women with sufficient quality of mtDNA were analyzed. After exclusions, 1978 women remained in the study population. Four different endpoints obtained from the National Patient register were studied: 1) OA, 2) OP 3) OA surgery, and 4) OP fracture. In the multivariate model adjustments were made for potential OA and OP risk factors.

Results

Women with low mtDNA-CN were older and had more activity at work. 125 women (6.32%) were affected by incident OP and 254 women (12.84%) had an OP fracture. Incident OA affected 451 women (22.80%) and 175 women (8.85%) had OA surgery. There were no associations between mtDNA-CN and incident risk of OA (Hazard ratio ​= ​1.00, 95% confidence interval 0.83-1.20), OA surgery (0.79, 0.58-1.07), OP (0.89, 0.62-1.27), or OP fracture (1.00, 0.78-1.29). However, incident OP was significantly associated with T-score (bone density), smoking, diabetes mellitus, and chronic obstructive bronchitis (COPD). OA was associated with body mass index and COPD.

Conclusions

The present study suggests that mtDNA-CN, reflecting mitochondrial dysfunction, is not a major predictor for incident OA or OP. However, due to the limited study size minor associations cannot be excluded.

Resolution of Optimal Mitochondrial and Nuclear DNA Enrichment in Target-Panel Sequencing and Physiological Mitochondrial DNA Copy Number Estimation in Liver Cancer and Non-Liver Cancer Subjects

Mitochondria generate energy to support cells. They are important organelles that engage in key biological pathways. The dysfunction of mitochondria can be linked to hepatocarcinogenesis, which has been actively explored in recent years. To investigate the mitochondrial dysfunction caused by genetic variations, target-panel sequencing is a flexible and promising strategy. However, the copy number of mitochondria generally exceeds nuclear DNA, which raises a concern that uneven target enrichment of mitochondrial DNA (mtDNA) and nuclear DNA (ncDNA) in target-panel sequencing would lead to an undesirably biased representation of them. To resolve this issue, we evaluated the optimal pooling of mtDNA probes and ncDNA probes by a series of dilutions of mtDNA probes in both genomic DNA (gDNA) and cell-free DNA (cfDNA) samples. The evaluation was based on read count, average sequencing depth and coverage of targeted regions. We determined that an mtDNA:ncDNA probe ratio of around 1:10 would offer a good balance of sequencing performance and cost effectiveness. Moreover, we estimated the median physiological mtDNA:ncDNA copy ratio as 38.1 and 2.9 in cfDNA and gDNA samples of non-liver cancer subjects, respectively, whereas they were 20.0 and 2.1 in the liver cancer patients. Taken together, this study revealed the appropriate pooling strategy of mtDNA probes and ncDNA probes in target-panel sequencing and suggested the normal range of physiological variation of the mtDNA:ncDNA copy ratio in non-liver cancer individuals. This can serve as a useful reference for future target-panel sequencing investigations of the mitochondrial genome in liver cancer.

Variability of Mitochondrial DNA Heteroplasmy: Association with Asymptomatic Carotid Atherosclerosis

Background and Objectives: Atherosclerosis is one of the main reasons for cardiovascular disease development. This study aimed to analyze the association of mtDNA mutations and atherosclerotic plaques in carotid arteries of patients with atherosclerosis and conditionally healthy study participants from the Novosibirsk region. Methods: PCR fragments of DNA containing the regions of 10 investigated mtDNA mutations were pyrosequenced. The heteroplasmy levels of mtDNA mutations were analyzed using a quantitative method based on pyrosequencing technology developed by M. A. Sazonova and colleagues. Results: In the analysis of samples of patients with atherosclerotic plaques of the carotid arteries and conditionally healthy study participants from the Novosibirsk region, four proatherogenic mutations in the mitochondrial genome (m.5178C>A, m.652delG, m.12315G>A and m.3256C>T) and three antiatherogenic mutations in mtDNA (m.13513G>A, m.652insG, and m.14846G>A) were detected. A west-east gradient was found in the distribution of the mtDNA mutations m.5178C>A, m.3256C>T, m.652insG, and m.13513G>A. Conclusions: Therefore, four proatherogenic mutations in the mitochondrial genome (m.5178C>A, m.652delG, m.12315G>A, and m.3256C>T) and three antiatherogenic mutations in mtDNA (m.13513G>A, m.652insG, and m.14846G>A) were detected in patients with atherosclerotic plaques in their carotid arteries from the Novosibirsk region.

Mitochondria: a breakthrough in combating rheumatoid arthritis

As a chronic autoimmune disease with complex aetiology, rheumatoid arthritis (RA) has been demonstrated to be associated with mitochondrial dysfunction since mitochondrial dysfunction can affect the survival, activation, and differentiation of immune and non-immune cells involved in the pathogenesis of RA. Nevertheless, the mechanism behind mitochondrial dysfunction in RA remains uncertain. Accordingly, this review addresses the possible role and mechanisms of mitochondrial dysfunction in RA and discusses the potential and challenges of mitochondria as a potential therapeutic strategy for RA, thereby providing a breakthrough point in the prevention and treatment of RA.

Lycopene alleviates Deoxynivalenol-induced toxicity in Porcine intestinal epithelial cells by mediating mitochondrial function

Deoxynivalenol (DON) is widely found in food and feed, posing a threat to human and animal health. Lycopene (Lyc) is a natural plant extracts with significant antioxidant properties. This study was conducted to investigate the protective effects of Lyc on IPEC-J2 cells upon DON exposure. The detection of cell viability and trypan blue staining showed that Lyc alleviated cell damage and decreased cell apoptotic rate induced by DON. The analysis of reactive oxygen species (ROS) level and antioxidant parameter measurements showed that Lyc significantly down-regulated the content of ROS and restored antioxidant enzyme activity. Furthermore, mitochondrial membrane potential (ΔΨm) detection, mitochondrial DNA copy number (mtDNAcn) assay and adenosine triphosphate (ATP) concentration detection showed Lyc improved mitochondrial function after DON exposure. The results of transcriptome analysis, ROS detection and CCK8 assay suggested that Lyc may activated the oxidative phosphorylation (OXPHOS) to improve mitochondrial function. Conclusively, our results suggested that Lyc alleviated DON-induced oxidative stress by improving mitochondrial function through OXPHOS signaling pathway.

Cross-species analysis uncovers the mitochondrial stress response in the hippocampus as a shared mechanism in mouse early life stress and human depression

Depression, or major depressive disorder, poses a significant burden for both individuals and society, affecting approximately 10.8% of the general population. This psychiatric disorder leads to approximately 800,000 deaths per year. A combination of genetic and environmental factors such as early life stress (ELS) increase the risk for development of depression in humans, and a clear role for the hippocampus in the pathophysiology of depression has been shown. Nevertheless, the underlying mechanisms of depression remain poorly understood, resulting in a lack of effective treatments. To better understand the core mechanisms underlying the development of depression, we used a cross-species design to investigate shared hippocampal pathophysiological mechanisms in mouse ELS and human depression. Mice were subjected to ELS by a maternal separation paradigm, followed by RNA sequencing analysis of the adult hippocampal tissue. This identified persistent transcriptional changes linked to mitochondrial stress response pathways, with oxidative phosphorylation and protein folding emerging as the main mechanisms affected by maternal separation. Remarkably, there was a significant overlap between the pathways involved in mitochondrial stress response we observed and publicly available RNAseq data from hippocampal tissue of depressive patients. This cross-species conservation of changes in gene expression of mitochondria-related genes suggests that mitochondrial stress may play a pivotal role in the development of depression. Our findings highlight the potential significance of the hippocampal mitochondrial stress response as a core mechanism underlying the development of depression. Further experimental investigations are required to expand our understanding of these mechanisms.