GWAS and ExWAS of blood mitochondrial DNA copy number identifies 71 loci and highlights a potential causal role in dementia.

Background: Mitochondrial DNA copy number (mtDNA-CN) is an accessible blood-based measurement believed to capture underlying mitochondrial (MT) function. The specific biological processes underpinning its regulation, and whether those processes are causative for disease, is an area of active investigation. Methods: We developed a novel method for array-based mtDNA-CN estimation suitable for biobank-scale studies, called 'automatic mitochondrial copy (AutoMitoC).' We applied AutoMitoC to 395,781 UKBiobank study participants and performed genome- and exome-wide association studies, identifying novel common and rare genetic determinants. Finally, we performed two-sample Mendelian randomization to assess whether genetically low mtDNA-CN influenced select MT phenotypes. Results: Overall, genetic analyses identified 71 loci for mtDNA-CN, which implicated several genes involved in rare mtDNA depletion disorders, deoxynucleoside triphosphate (dNTP) metabolism, and the MT central dogma. Rare variant analysis identified SAMHD1 mutation carriers as having higher mtDNA-CN (beta = 0.23 SDs; 95% CI, 0.18-0.29; p=2.6 × 10-19), a potential therapeutic target for patients with mtDNA depletion disorders, but at increased risk of breast cancer (OR = 1.91; 95% CI, 1.52-2.40; p=2.7 × 10-8). Finally, Mendelian randomization analyses suggest a causal effect of low mtDNA-CN on dementia risk (OR = 1.94 per 1 SD decrease in mtDNA-CN; 95% CI, 1.55-2.32; p=7.5 × 10-4). Conclusions: Altogether, our genetic findings indicate that mtDNA-CN is a complex biomarker reflecting specific MT processes related to mtDNA regulation, and that these processes are causally related to human diseases. Funding: No funds supported this specific investigation. Awards and positions supporting authors include: Canadian Institutes of Health Research (CIHR) Frederick Banting and Charles Best Canada Graduate Scholarships Doctoral Award (MC, PM); CIHR Post-Doctoral Fellowship Award (RM); Wellcome Trust Grant number: 099313/B/12/A; Crasnow Travel Scholarship; Bongani Mayosi UCT-PHRI Scholarship 2019/2020 (TM); Wellcome Trust Health Research Board Irish Clinical Academic Training (ICAT) Programme Grant Number: 203930/B/16/Z (CJ); European Research Council COSIP Grant Number: 640580 (MO); E.J. Moran Campbell Internal Career Research Award (MP); CISCO Professorship in Integrated Health Systems and Canada Research Chair in Genetic and Molecular Epidemiology (GP).

Our cells are powered by small internal compartments known as mitochondria, which host several copies of their own 'mitochondrial' genome. Defects in these semi-autonomous structures are associated with a range of severe, and sometimes fatal conditions: easily checking the health of mitochondria through cheap, quick and non-invasive methods can therefore help to improve human health. Measuring the concentration of mitochondrial DNA molecules in our blood cells can help to estimate the number of mitochondrial genome copies per cell, which in turn act as a proxy for the health of the compartment. In fact, having lower or higher concentration of mitochondrial DNA molecules is associated with diseases such as cancer, stroke, or cardiac conditions. However, current approaches to assess this biomarker are time and resource-intensive; they also do not work well across people with different ancestries, who have slightly different versions of mitochondrial genomes. In response, Chong et al. developed a new method for estimating mitochondrial DNA concentration in blood samples. Called AutoMitoC, the automated pipeline is fast, easy to use, and can be used across ethnicities. Applying this method to nearly 400,000 individuals highlighted 71 genetic regions for which slight sequence differences were associated with changes in mitochondrial DNA concentration. Further investigation revealed that these regions contained genes that help to build, maintain, and organize mitochondrial DNA. In addition, the analyses yield preliminary evidence showing that lower concentration of mitochondrial DNA may be linked to a higher risk of dementia. Overall, the work by Chong et al. demonstrates that AutoMitoC can be used to investigate how mitochondria are linked to health and disease in populations across the world, potentially paving the way for new therapeutic approaches.

Dietary supplementation of gingerols- and shogaols-enriched ginger root extract attenuate pain-associated behaviors while modulating gut microbiota and metabolites in rats with spinal nerve ligation.

Neuroinflammation is a central factor in neuropathic pain (NP). Ginger is a promising bioactive compound in NP management due to its anti-inflammatory property. Emerging evidence suggests that gut microbiome and gut-derived metabolites play a key role in NP. We evaluated the effects of two ginger root extracts rich in gingerols (GEG) and shogaols (SEG) on pain sensitivity, anxiety-like behaviors, circulating cell-free mitochondrial DNA (ccf-mtDNA), gut microbiome composition, and fecal metabolites in rats with NP. Sixteen male rats were divided into four groups: sham, spinal nerve ligation (SNL), SNL+0.75%GEG in diet, and SNL+0.75%SEG in diet groups for 30 days. Compared to SNL group, both SNL+GEG and SNL+SEG groups showed a significant reduction in pain- and anxiety-like behaviors, and ccf-mtDNA level. Relative to the SNL group, both SNL+GEG and SNL+SEG groups increased the relative abundance of Lactococcus, Sellimonas, Blautia, Erysipelatoclostridiaceae, and Anaerovoracaceae, but decreased that of Prevotellaceae UCG-001, Rikenellaceae RC9 gut group, Mucispirillum and Desulfovibrio, Desulfovibrio, Anaerofilum, Eubacterium siraeum group, RF39, UCG-005, Lachnospiraceae NK4A136 group, Acetatifactor, Eubacterium ruminantium group, Clostridia UCG-014, and an uncultured Anaerovoracaceae. GEG and SEG had differential effects on gut-derived metabolites. Compared to SNL group, SNL+GEG group had higher level of 1'-acetoxychavicol acetate, (4E)-1,7-Bis(4-hydroxyphenyl)-4-hepten-3-one, NP-000629, 7,8-Dimethoxy-3-(2-methyl-3-buten-2-yl)-2H-chromen-2-one, 3-{[4-(2-Pyrimidinyl)piperazino]carbonyl}-2-pyrazinecarboxylic acid, 920863, and (1R,3R,7R,13S)-13-Methyl-6-methylene-4,14,16-trioxatetracyclo[11.2.1.0∼1,10∼.0∼3,7∼]hexadec-9-en-5-one, while SNL+SEG group had higher level for (±)-5-[(tert-Butylamino)-2'-hydroxypropoxy]-1_2_3_4-tetrahydro-1-naphthol and dehydroepiandrosteronesulfate. In conclusion, ginger is a promising functional food in the management of NP, and further investigations are necessary to assess the role of ginger on gut-brain axis in pain management.

The Effects of Korean Red Ginseng on Biological Aging and Antioxidant Capacity in Postmenopausal Women: A Double-Blind Randomized Controlled Study.

Postmenopausal women are vulnerable to aging and oxidative stress due to reduced estrogen. Previous studies have shown that Korean red ginseng (KRG) has beneficial effects on aging and antioxidant capacity. Therefore, we evaluated the effects of KRG on biological aging and antioxidant capacity in postmenopausal women. This study conducted a double-blinded, placebo-controlled clinical trial. The participants were randomly administered KRG or a placebo, and the following metrics were measured: mitochondria DNA (mtDNA) copy number as an indicator of biological aging and, total antioxidant status (TAS) as a marker of antioxidant capacity. Clinical symptoms of fatigue, as measured by the fatigue severity scale, were assessed before and after KRG administration. There were 63 participants, of whom 33 received KRG and 30 received a placebo. The mtDNA copy number (KRG group: 1.58 ± 2.05, placebo group: 0.28 ± 2.36, p = 0.023) and TAS (KRG group: 0.11 ± 0.25 mmol/L, placebo group: -0.04 ± 0.16 mmol/L, p = 0.011) increased and the fatigue severity scale (KRG group: -7 ± 12, placebo group: -1 ± 11, p = 0.033) decreased significantly more in the KRG group than the placebo group. KRG significantly increased the mtDNA copy number, total antioxidant status, and improved symptoms of fatigue in postmenopausal women.

Daily Oral Supplementation with 60 mg of Elemental Iron for 12 Weeks Alters Blood Mitochondrial DNA Content, but Not Leukocyte Telomere Length in Cambodian Women.

There is limited evidence regarding the potential risk of untargeted iron supplementation, especially among individuals who are iron-replete or have genetic hemoglobinopathies. Excess iron exposure can increase the production of reactive oxygen species, which can lead to cellular damage. We evaluated the effect of daily oral supplementation on relative leukocyte telomere length (rLTL) and blood mitochondrial DNA (mtDNA) content in non-pregnant Cambodian women (18-45 years) who received 60 mg of elemental iron as ferrous sulfate (n = 190) or a placebo (n = 186) for 12 weeks. Buffy coat rLTL and mtDNA content were quantified by monochrome multiplex quantitative polymerase chain reaction. Generalized linear mixed-effects models were used to predict the absolute and percent change in rLTL and mtDNA content after 12 weeks. Iron supplementation was not associated with an absolute or percent change in rLTL after 12 weeks compared with placebo (ß-coefficient: -0.04 [95% CI: -0.16, 0.08]; p = 0.50 and ß-coefficient: -0.96 [95% CI: -2.69, 0.77]; p = 0.28, respectively). However, iron supplementation was associated with a smaller absolute and percent increase in mtDNA content after 12 weeks compared with placebo (ß-coefficient: -11 [95% CI: -20, -2]; p = 0.02 and ß-coefficient: -11 [95% CI: -20, -1]; p= 0.02, respectively). Thus, daily oral iron supplementation for 12 weeks was associated with altered mitochondrial homeostasis in our study sample. More research is needed to understand the risk of iron exposure and the biological consequences of altered mitochondrial homeostasis in order to inform the safety of the current global supplementation policy.

Joint effects of mitochondrial DNA4977 deletion and serum folate deficiency on coronary artery disease in type 2 diabetes mellitus.

BACKGROUND & AIMS: The 4977-bp mitochondrial deletion (mtDNA4977 deletion), as a hallmark of mitochondrial oxidative damage, may play an important role in coronary artery disease (CAD), but its interaction with folate deficiency among diabetic patients is largely unknown. We aimed to explore the joint association of leukocyte mtDNA4977 deletion and serum folate status with obstructive CAD in Chinese adults with type 2 diabetes. METHODS: We cross-sectionally analyzed the angiographic data of 2017 diabetic patients without B-vitamin supplementation. Of the 2017 participants, 756 who received percutaneous coronary intervention (PCI) completed prospective follow-up of one year. In vitro, we explored the mediation effects of mitochondrial reactive oxygen species (mtROS) in folic acid (FA)-deficient human aortic smooth muscle cells (HASMCs) under hyperglycemic conditions. RESULTS: Cross-sectionally, the multivariate odds ratios (ORs) for obstructive CAD were 1.41 (95% CI: 1.29-1.55) for greater mtDNA4977 deletion, and 1.15 (95% CI: 1.05-1.25) for lower folate levels. Particularly, the combination of high mtDNA4977 deletion (top tertile) and folate deficiency (serum folate < 6 ng/mL) was associated with more than 2-fold increased odds of having obstructive CAD and higher degrees of coronary stenosis. Prospectively, the hazard ratio for all-cause death at 1-year after PCI was up to 2.37 (95% CI: 1.21-4.63) for folate-deficient participants in the top tertile of mtDNA4977 deletion. In HASMCs, the adverse effects of FA deficiency were aggravated by induction of mtROS, and attenuated by scavenging of mtROS. CONCLUSIONS: The risk of obstructive CAD may be greatly increased by the interaction between greater mtDNA4977 deletion and folate deficiency among diabetic patients.

Plasma circulating cell-free mitochondrial DNA in the assessment of Friedreich's ataxia.

Friedreich's ataxia (FRDA) is one of the most devastating childhood onset neurodegenerative disease affecting multiple organs in the course of progression. FRDA is associated with mitochondrial dysfunction due to deficit in a nuclear encoded mitochondrial protein, frataxin. Identification of disease-specific biomarker for monitoring the severity remains to be a challenging topic. This study was aimed to identify whether circulating cell-free nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) in blood plasma can be a potential biomarker for FRDA. Clinical information was assessed using International Cooperative Ataxia Rating Scale and the disease was confirmed using Long-range PCR for GAA repeat expansion within the gene encoding frataxin. The frataxin expression was measured using Western blot. Plasma nDNA and mtDNA levels were quantified by Multiplex real-time PCR. The major observation is that the levels of nDNA found to be increased, whereas mtDNA levels were reduced significantly in the plasma of FRDA patients (n=21) as compared to healthy controls (n=21). Further, plasma mtDNA levels showed high sensitivity (90%) and specificity (76%) in distinguishing from healthy controls with optimal cutoff indicated at 4.1×10(5)GE/mL. Interestingly, a small group of follow-up patients (n=9) on intervention with, a nutrient supplement, omega-3 fatty acid (a known enhancer of mitochondrial metabolism) displayed a significant improvement in the levels of plasma mtDNA, supporting our hypothesis that plasma mtDNA can be a potential monitoring or prognosis biomarker for FRDA.

Wonder or fake - investigations in the case of the stigmatisation of Therese Neumann von Konnersreuth.

We investigated two compresses used by Therese Neumann (T.N.), a woman who lived from 1898 until 1962 in Konnersreuth, Germany. The compresses were soaked with blood during the appearance of stigmata on T.N.'s body on a Friday. T.N. became very popular among the faithful in Germany at this time. The question was whether this blood was from T.N. herself or from a family relative or an animal. The comparison of the HV1 and HV2 mtDNA sequence obtained from the compresses with the sequences from a reference sample from a maternally related niece of T.N. revealed an identity. Furthermore, we obtained a short tandem repeat (STR) profile from the bloodstains that were identical with the STR profile from a gummed envelope. The envelope contained a letter written by T.N. in the 1930s. Therefore, our investigations gave no indication for any manipulation.

[Clinical study on treatment of mild cognitive impairment by modified wuzi yanzong granule].

OBJECTIVE: To observe the clinical efficacy and safety of modified Wuzi Yanzong Granule (MWYG) in treating mild cognitive impairment (MCI), and to explore its mechanism. METHODS: Forty-four MCI patients were selected referring to the international recognized Peterson's criteria and randomly divided into two groups, the treated group treated with MWYG and the control group treated with Ginkgo leaf extraction, with the course of 3 months for both groups. Changes of memorial quotient (MQ), superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, mitochondrial DNA (mtDNA) deletion rate and acetylcholinesterase (AchE) before and after treatment were observed. RESULTS: After treatment, levels of MQ, serum SOD activity increased and serum MDA content, mtDNA deletion rate and AchE decreased in both groups (P < 0.01), but the difference between the two groups was insignificant. No adverse reaction was found in two groups. CONCLUSION: Both MWYG and Ginkgo leaf capsule can effectively improve the memorial function of patients with MCI, the therapeutic mechanism is possibly related with the actions in reducing AchE activity, improving free radical metabolism, and alleviating mitochondrial DNA oxidation damage.