Subtype-Specific Association of Mitochondrial DNA Copy Number With Poststroke/TIA Outcomes in 10 241 Patients in China

BACKGROUND

Mitochondrial DNA copy number (mtDNA-CN) is associated with the severity and mortality in patients with stroke, but the associations in different stroke subtypes remain unexplored.

METHODS

We conducted an observational prospective cohort analysis on patients with ischemic stroke or transient ischemic attack enrolled in the Third China National Stroke Registry. We applied logistic models to assess the association of mtDNA-CN with functional outcome (modified Rankin Scale score, 3-6 versus 0-2) and Cox proportional hazard models to assess the association with stroke recurrence (treating mortality as a competing risk) and mortality during a 12-month follow-up, adjusting for sex, age, physical activity, National Institutes of Health Stroke Scale at admission, history of stroke and peripheral artery disease, small artery occlusion, and interleukin-6. Subgroup analyses stratified by age and stroke subtypes were conducted.

RESULTS

The Third China National Stroke Registry enrolled 15 166 patients, of which 10 241 with whole-genome sequencing data were retained (mean age, 62.2 [SD, 11.2] years; 68.8% men). The associations between mtDNA-CN and poststroke/transient ischemic attack outcomes were specific to patients aged ≤65 years, with lower mtDNA-CN significantly associated with stroke recurrence in 12 months (subdistribution hazard ratio, 1.15 per SD lower mtDNA-CN [95% CI, 1.04-1.27]; P=5.2×10-3) and higher all-cause mortality in 3 months (hazard ratio, 2.19 [95% CI, 1.41-3.39]; P=5.0×10-4). Across subtypes, the associations of mtDNA-CN with stroke recurrence were specific to stroke of undetermined cause (subdistribution hazard ratio, 1.28 [95% CI, 1.11-1.48]; P=6.6×10-4). In particular, lower mtDNA-CN was associated with poorer functional outcomes in stroke of undetermined cause patients diagnosed with embolic stroke of undetermined source (odds ratio, 1.53 [95% CI, 1.20-1.94]; P=5.4×10-4), which remained significant after excluding patients with recurrent stroke (odds ratio, 1.49 [95% CI, 1.14-1.94]; P=3.0×10-3).

CONCLUSIONS

Lower mtDNA-CN is associated with higher stroke recurrence rate and all-cause mortality, as well as poorer functional outcome at follow-up, among stroke of undetermined cause, embolic stroke of undetermined source, and younger patients.

Characterization of the Mitochondrial Genetic Landscape in Abdominal Aortic Aneurysm

Background Abdominal aortic aneurysm (AAA) is a vascular disease with a mortality rate of >80% if ruptured. Mitochondrial dysfunction has been previously implicated in AAA pathogenesis. In this study, we aimed to characterize the mitochondrial genetic landscape in AAA. Methods and Results Whole mitochondrial genome sequencing and bioinformatics analysis were performed in comorbidity matched 48 cases without AAA and 48 cases with AAA, objectively diagnosed, and selected from a cohort of 65-year-old men recruited for a screening program. We identified differential mutational landscapes in men with and without AAA, with errors in mitochondrial DNA replication or repair as potential sources. Heteroplasmic insertions and overall heteroplasmy of structural rearrangements were significantly elevated in AAA cases. Three heteroplasmic variants were associated with risk factors of AAA: leukocyte concentration, plasma glucose, and cholesterol levels, respectively. Interestingly, mutations were more prevalent in regulatory part of the mitochondria, the displacement loop region, in AAA as compared with controls (P value <0.05), especially in the conserved and critical mitochondrial extended termination-associated sequence region. Moreover, we report a novel 24 bp mitochondrial DNA duplication present exclusively in cases with AAA (4%) and 75% of the unmatched AAA biopsies. Finally, the haplogroup cluster JTU was overrepresented in AAA and significantly associated with a positive family history of AAA (odds ratio, 2.9 [95% CI, 1.1-8.1]). Conclusions This is the first study investigating the mitochondrial genome in AAA, where important genetic alterations and haplogroups associated with AAA and clinical risk factors were identified. Our findings have the potential to fill in gaps in the missing genetic information on AAA.

Mitochondrial dysfunction in a rat model and the related risk of metabolic disorders

OBJECTIVE

To explore whether kidney deficiency (KYD) is prone to metabolic disorders may be linked to impaired mitochondrial function in thermogenesis and metabolic tissues.

METHODS

A rat model of KYD was used, which was established using Sprague Dawley rat dams with warm preference subjected to herbal treatment that can improve kidney . The human relevance was confirmed by reduced serum corticosterone levels, and increased preference for warm location.

RESULTS

KYD Rats were underdeveloped. Adenosine-triphosphate (ATP) production was reduced in the brown fat, but increased in the muscle. However, oxidative phosphorylated complexes to generate ATP and mitochondrial biogenesis marker were reduced in both tissues. When the second insult of high-fat diet (HFD) was introduced, KYD rats gained less weight yet developed more severe lipid and glucose metabolic disorders. This may be driven by disregulated liver gluconeogenesis marker forkhead box protein O1 and lipid metabolic regulator cholesterol 7 alpha-hydroxylase.

CONCLUSION

KYD rats exhibited reduced mito-chondrial function in the brown fat, but were partially compensated by skeletal muscle, associated with the phenotype of warm preference and metabolic disorder, which was further exacerbated by additional HFD consumption. Future studies can focus on treatment targetting mitochondria function to reverse this phenotype.

Neuromitochondrial Disorders : Genomic Basis and an Algorithmic Approach to Imaging Diagnostics

Mitochondrial disorders have been an enigma for a long time due to the varied clinical presentations. Although a genetic confirmation will be mandatory most of the time, half the number of Leigh syndrome would be negative for genetic mutations. There are a growing number of mutations in clinical practice, which escape detection on routine clinical exome sequencing. Imaging would render help in pointing towards a mitochondrial disorder. There are a few case reports which brief about specific mitochondrial mutations and their specific imaging appearance. This article tries to provide a comprehensive review on the imaging-genomic correlation of mitochondrial disorders with an objective of performing a specific genetic testing to arrive at an accurate diagnosis.

Extracellular Tuning of Mitochondrial Respiration Leads to Aortic Aneurysm

Supplemental Digital Content is available in the text.

Background:

Marfan syndrome (MFS) is an autosomal dominant disorder of the connective tissue caused by mutations in the FBN1 (fibrillin-1) gene encoding a large glycoprotein in the extracellular matrix called fibrillin-1. The major complication of this connective disorder is the risk to develop thoracic aortic aneurysm. To date, no effective pharmacologic therapies have been identified for the management of thoracic aortic disease and the only options capable of preventing aneurysm rupture are endovascular repair or open surgery. Here, we have studied the role of mitochondrial dysfunction in the progression of thoracic aortic aneurysm and mitochondrial boosting strategies as a potential treatment to managing aortic aneurysms.

Methods:

Combining transcriptomics and metabolic analysis of aortas from an MFS mouse model (Fbn1^c1039g/+) and MFS patients, we have identified mitochondrial dysfunction alongside with mtDNA depletion as a new hallmark of aortic aneurysm disease in MFS. To demonstrate the importance of mitochondrial decline in the development of aneurysms, we generated a conditional mouse model with mitochondrial dysfunction specifically in vascular smooth muscle cells (VSMC) by conditional depleting Tfam (mitochondrial transcription factor A; Myh11-Cre^ERT2Tfam^flox/flox mice). We used a mouse model of MFS to test for drugs that can revert aortic disease by enhancing Tfam levels and mitochondrial respiration.

Results:

The main canonical pathways highlighted in the transcriptomic analysis in aortas from Fbn1^c1039g/+ mice were those related to metabolic function, such as mitochondrial dysfunction. Mitochondrial complexes, whose transcription depends on Tfam and mitochondrial DNA content, were reduced in aortas from young Fbn1^c1039g/+ mice. In vitro experiments in Fbn1-silenced VSMCs presented increased lactate production and decreased oxygen consumption. Similar results were found in MFS patients. VSMCs seeded in matrices produced by Fbn1-deficient VSMCs undergo mitochondrial dysfunction. Conditional Tfam-deficient VSMC mice lose their contractile capacity, showed aortic aneurysms, and died prematurely. Restoring mitochondrial metabolism with the NAD precursor nicotinamide riboside rapidly reverses aortic aneurysm in Fbn1^c1039g/+ mice.

Conclusions:

Mitochondrial function of VSMCs is controlled by the extracellular matrix and drives the development of aortic aneurysm in Marfan syndrome. Targeting vascular metabolism is a new available therapeutic strategy for managing aortic aneurysms associated with genetic disorders.

Atlantic Forest Malaria: A Review of More than 20 Years of Epidemiological Investigation

In the south and southeast regions of Brazil, cases of malaria occur outside the endemic Amazon region near the Atlantic Forest in some coastal states, where Plasmodium vivax is the recognized parasite. Characteristics of cases and vectors, especially Anopheles (Kerteszia) cruzii, raise the hypothesis of a zoonosis with simians as reservoirs. The present review aims to report on investigations of the disease over a 23-year period. Two main sources have provided epidemiological data: the behavior of Anopheles vectors and the genetic and immunological aspects of Plasmodium spp. obtained from humans, Alouatta simians, and Anopheles spp. mosquitoes. Anopheles (K.) cruzii is the most captured species in the forest canopy and is the recognized vector. The similarity between P. vivax and Plasmodium simium and that between Plasmodium malariae and Plasmodium brasilianum shared between simian and human hosts and the involvement of the same vector in the transmission to both hosts suggest interspecies transfer of the parasites. Finally, recent evidence points to the presence of Plasmodium falciparum in a silent cycle, detected only by molecular methods in asymptomatic individuals and An. (K.) cruzii. In the context of malaria elimination, it is paramount to assemble data about transmission in such non-endemic low-incidence areas.

[Phenotype and genotype of twelve Chinese children with mitochondrial DNA depletion syndromes]

Objective: To explore the phenotype and genotype of mitochondrial DNA depletion syndromes (MDS) in Chinese children. Methods: The clinical and genetic data of 12 MDS patients (8 were boys and 4 were girls) diagnosed in the Department of Neurology in Beijing Children's Hospital, Capital Medical University from October 2010 to April 2018 were retrospectively collected and analyzed. Results: The developmental milestones were normal or mildly retardated before disease onset. The age of onset ranged from 0 to 2.9-year-old. Most cases developed postnatal or after infection. The most common initial symptoms were feeding difficulty, seizure, muscle weakness, psychomotor regression and hepatic dysfunction. At the last evaluation, all the patients had developmental retardation, failure to thrive, muscle weakness, and dysphagia. Other clinical features were weight loss (9 cases), hearing impairment (7 cases), ptosis (6 cases), seizure (5 cases), dyspnea (4 cases), visual impairment (1 case), hirsutism (1 case), lactic acidosis (7 cases), elevated hepatic enzymes (4 cases) and creatine kinase (2 cases), elevated protein in cerebrospinal fluid (3 cases), abnormalities on screening for inborn error of metabolism (10 cases) and brain magnetic resonance imaging (MRI) (10 cases), abnormal electromyogram (including neurogenic or myogenic injury) (5 cases). Five patients died of infection or multiple organ failure. A total of 18 novel mutations presented below were detected in these patients. Among the 6 cases of encephalomyopathy, there were 3 with SUCLG1 mutation (c. 916G>T, c. 619T>C, c. 980dupT were novel), 2 with SUCLA2 mutation (c. 851G>A, c.971G>A were novel), and one with RRM2B mutation (c.456-2A>G, c.212T>C were novel). All the cases of hepatic encephalopathy all had POLG mutations (c. 3151G>A, c. 2294C>T, c. 2858G>C, c. 680G>A and c. 150_158delGCAGCAGCA were novel). Two cases of infantile-onset spinocerebellar ataxia had TWNK mutations (c. 1163C>T, c. 1319T>C, c. 1388G>A and c. 257_258delAG were novel). One case of myopathy had TK2 mutations (c.557C>G and c.341A>T were novel). Conclusions: The clinical and genetic features of MDS were heterogeneous. Eighteen novel mutations in six MDS related genes were reported, which expanded the genetic spectrum of MDS in Chinese children.

[Clinical research progress of gene therapy for Leber hereditary optic neuropathy]

Leber hereditary optic neuropathy (LHON) is a mitochondria hereditary eye disease that involves with retinal ganglion cells (RGCs) resulting eventually in degeneration and atrophy of optic nerve. The three mitochondrial DNA mutations (ND4 G11778A, ND1G3460A, ND6T14484C) have been recognized as the primary mutation locus of LHON. Currently there is no effective therapy for LHON. The result of a clinical trial launched in 2007 indicated that intraocular injection of the recombination of adeno-associated virus and target gene is an effective and safe cure for Leber's Congenital Amaurosis (LCA), which brings hope of treating other hereditary eye diseases with gene therapy. Since LHON mainly involves with RGCs, the target gene can be delivered directly to RGCs with the means of injecting the recombination into vitreous cavity, therefore resulting in less damage to retina as compared to other gene therapy for LCA which require the drug to be injected under the retina. This article summarizes the research progress of the clinical trial relevant to gene therapy for LHON. (Chin J Ophthalmol, 2018, 54: 636-640).

[A study of clinical and genetic characteristics of a Leber hereditary optic neuropathy family with the heteroplasmic m.14484T>C mutation]

Objective: To study clinical and genetic characteristics of a Leber hereditary optic neuropathy (LHON) family with the heteroplasmic m.14484T>C mutation. Methods: A cross-sectional study. The objects of the study included a 31-year-old male LHON patient with the heteroplasmic m.14484T>C mutation (the proband) who visited Department of Ophthalmology in the Affiliated Central Hospital of Qingdao University in March 2015 and other 36 matrilineal relatives in a four-generation family (12 males and 24 females aged 2-81 years, median 27 years). The visual acuity, intraocular pressure, fundus, color vision, visual field, visual evoked potential and optical coherence tomography were evaluated in maternal members. The mitochondrial DNA (mtDNA) sequence of fragments including m.14484 loci was detected by Sanger sequencing in 33 members. The sequencing peaks were analyzed by QSVanalyzer software to get the heteroplasmy levels of m.14484T>C mutation. The mtDNA of the proband was amplified by PCR and sequenced. Assembled sequence of mtDNA was compared with the updated consensus Cambridge sequence. The differences in visual evoked potential, optical coherence tomography and heteroplasmy levels were compared between two groups by the t-test, and among multiple groups by the single factor variance analysis. Results: Among the 33 maternal members of the family, 4 patients, 28 carriers and 1 person without a mutation were confirmed. The penetrance was 12.5% (4/32) . In addition to 4 patients with obvious abnormality on the ophthalmic examination, 5 carriers also appeared anomaly on the electrophysiological and visual function examinations. Compared to carriers, the amplitude of P100 was obviously decreased in the LHON patients[ (5.6±2.6) μV vs. (15.6±9.6) μV, t=2.880, P=0.006]. Significantly reduced values were seen in the average retinal nerve fiber layer thickness[ (71±17) μm vs. (99±11) μm, t=5.969, P< 0.001], in each side of the sub-area macular thickness, and in the nasal side of the lateral sub-area macular thickness [ (260±16) μm vs. (291±12) μm, t=5.593, P<0.001] between the LHON patients and carriers. The heteroplasmic levels were 80%±3% in the LHON patients, and 27%±18% in the unaffected members;the difference was significant (t=-8.395, P<0.001). The average degree of heteroplasmy had no difference between male and female members (48%±34% vs. 35%±28%, t=-1.147, P=0.258). The average mutation load was 29%±14% in the second generation members, 36%±29% in the third generation members, and 51%±36% in the fourth generation members;the differences were not statistically significant (F=1.152, P=0.330). The difference in the heteroplasmic levels was not statistically significant between mothers and their offspring (31%±25% vs. 42%±32%, t=1.165, P=0.251). Compared to Cambridge consensus sequence, 41 mutations was found in mtDNA of the proband, of which, 10 were missense mutations, including mutations m.4216T>C and m.3394T>C. According to the phylogenetic tree, the haplotype of the proband was M9a (M9a1a1c1a). Conclusions: In the family with the heteroplasmic m.14484T>C mutation, clinical manifestations of LHON appear in the individuals whose heteroplasmic level is more than 75%, and all of patients show typical chronic optic atrophy on the ophthalmic examination. The carriers with the m.14484T>C mutation also appear anomaly on the electrophysiological and visual function examinations. The heteroplasmic level of m.14484T>C mutation has a tendency to increase during the transmission in the family. The primary mutation m.14484T>C coordinate mutations m.4216T>C and m.3394T>C to increase the penetrance and incidence of abnormal visual function in carriers. (Chin J Ophthalmol, 2018, 54: 526-534).

Three Reportedly Unrelated Families With Liddle Syndrome Inherited From a Common Ancestor

Liddle syndrome is considered a rare Mendelian hypertension. We have previously described 3 reportedly unrelated families, native of an Italian area around the Strait of Messina, carrying the same mutation (βP617L) of the epithelial sodium channel. The aims of our study were (1) to evaluate whether a close genomic relationship exists between the 3 families through the analysis of mitochondrial DNA and Y chromosome; and (2) to quantify the genomic relatedness between the patients with Liddle syndrome belonging to the 3 families and assess the hypothesis of a mutation shared through identity by descent. HVRI (the hypervariable region I) of the mitochondrial DNA genome and the Y chromosome short tandem repeats profiles were analyzed in individuals of the 3 families. Genotyping 542 585 genome-wide single nucleotide polymorphisms was performed in all the patients with Liddle syndrome of the 3 families and some of their relatives. A panel of 780 healthy Italian adult samples typed for the same set of markers was used as controls. espite different lineages between the 3 families based on the analysis of mitochondrial DNA and Y chromosome, the 3 probands and their 6 affected relatives share the same ≈5 Mbp long haplotype which encompasses the mutant allele. Using an approach based on coalescent theory, we estimate that the 3 families inherited the mutant allele from a common ancestor ≈13 generations ago and that such an ancestor may have left ≈20 carriers alive today. The prevalence of Liddle syndrome in the region of origin of the 3 families may be much higher than that estimated worldwide.

[Whole Genome Sequencing of Human mtDNA Based on Ion Torrent PGM™ Platform]

OBJECTIVES

To analyze and detect the whole genome sequence of human mitochondrial DNA （mtDNA） by Ion Torrent PGM™ platform and to study the differences of mtDNA sequence in different tissues.

METHODS

Samples were collected from 6 unrelated individuals by forensic postmortem examination, including chest blood, hair, costicartilage, nail, skeletal muscle and oral epithelium. Amplification of whole genome sequence of mtDNA was performed by 4 pairs of primer. Libraries were constructed with Ion Shear™ Plus Reagents kit and Ion Plus Fragment Library kit. Whole genome sequencing of mtDNA was performed using Ion Torrent PGM™ platform. Sanger sequencing was used to determine the heteroplasmy positions and the mutation positions on HVⅠ region.

RESULTS

The whole genome sequence of mtDNA from all samples were amplified successfully. Six unrelated individuals belonged to 6 different haplotypes. Different tissues in one individual had heteroplasmy difference. The heteroplasmy positions and the mutation positions on HVⅠ region were verified by Sanger sequencing. After a consistency check by the Kappa method, it was found that the results of mtDNA sequence had a high consistency in different tissues.

CONCLUSIONS

The testing method used in present study for sequencing the whole genome sequence of human mtDNA can detect the heteroplasmy difference in different tissues, which have good consistency. The results provide guidance for the further applications of mtDNA in forensic science.

[Relationship between mitochondrial DNA copy number, membrane potential of human embryo and embryo morphology]

Objective: To explore the relationship between the embryo with the different morphological types in the third day and its mitochondrial copy number, the membrane potential. Methods: Totally 117 embryos with poor development after normal fertilization and were not suitable transferred in the fresh cycle and 106 frozen embryos that were discarded voluntarily by infertility patients with in vitro fertilization-embryo transfer after successful pregnancy were selected. According to evaluation of international standard in embryos, all cleavage stage embryos were divided into class Ⅰ frozen embryo group (n=64), class Ⅱ frozen embryo group (n=42) and class Ⅲ fresh embryonic group (not transplanted embryos; n=117). Real-time PCR and confocal microscopy methods were used to detect mitochondrial DNA (mtDNA) copy number and the mitochondrial membrane potential of a single embryo. The differences between embryo quality and mtDNA copy number and membrane potential of each group were compared. Results: The copy number of mtDNA and the mitochondrial membrane potential in class Ⅲ fresh embryonic group [(1.7±1.0)×10(5) copy/μl, 1.56±0.32] were significantly lower than those in class Ⅰ frozen embryo group [(3.4±1.7)×10(5) copy/μl, 2.66±0.21] and class Ⅱ frozen embryo group [(2.6±1.2)×10(5) copy/μl, 1.80±0.32; all P<0.05]. The copy number of mtDNA and the mitochondrial membrane potential in classⅠ frozen embryo group were significantly higher than those in classⅡ frozen embryo group (both P<0.05). Conclusion: The mtDNA copy number and the mitochondrial membrane potential of embryos of the better quality embryo are higher.

Mitochondrial genome of Plasmodium vivax/simium detected in an endemic region for malaria in the Atlantic Forest of Espírito Santo state, Brazil: do mosquitoes, simians and humans harbour the same parasite?

Background

The transmission of malaria in the extra-Amazonian regions of Brazil, although interrupted in the 1960s, has persisted to the present time in some areas of dense Atlantic Forest, with reports of cases characterized by particular transmission cycles and clinical presentations. Bromeliad-malaria, as it is named, is particularly frequent in the state of Espírito Santo, with Plasmodium vivax being the parasite commonly recognized as the aetiologic agent of human infections. With regard to the spatial and temporal distances between cases reported in this region, the transmission cycle does not fit the traditional malaria cycle. The existence of a zoonosis, with infected simians participating in the epidemiology, is therefore hypothesized. In the present study, transmission of bromeliad-malaria in Espírito Santo is investigated, based on the complete mitochondrial genome of DNA extracted from isolates of Plasmodium species, which had infected humans, a simian from the genus Allouata, and Anopheles mosquitoes. Plasmodium vivax/simium was identified in the samples by both nested PCR and real-time PCR. After amplification, the mitochondrial genome was completely sequenced and compared with a haplotype network which included all sequences of P. vivax/simium mitochondrial genomes sampled from humans and simians from all regions in Brazil.

Results

The haplotype network indicates that humans and simians from the Atlantic Forest become infected by the same haplotype, but some isolates from humans are not identical to the simian isolate. In addition, the plasmodial DNA extracted from mosquitoes revealed sequences different from those obtained from simians, but similar to two isolates from humans.

Conclusions

These findings strengthen support for the hypothesis that in the Atlantic Forest, and especially in the state with the highest frequency of bromeliad-malaria in Brazil, parasites with similar molecular backgrounds are shared by humans and simians. The recognized identity between P. vivax and P. simium at the species level, the sharing of haplotypes, and the participation of the same vector in transmitting the infection to both host species indicate interspecies transference of the parasites. However, the intensity, frequency and direction of this transfer remain to be clarified.

Electronic supplementary material

The online version of this article (10.1186/s12936-017-2080-9) contains supplementary material, which is available to authorized users.

Mitochondrial Oxidative Stress Promotes Atherosclerosis and Neutrophil Extracellular Traps in Aged Mice

RATIONALE

Mitochondrial oxidative stress (mitoOS) has been shown to be increased in various cell types in human atherosclerosis and with aging. However, the role of cell type-specific mitoOS in atherosclerosis in the setting of advanced age and the molecular mechanisms remains to be determined in vivo.

OBJECTIVE

The aim of this study was to examine the role of myeloid cell mitoOS in atherosclerosis in aged mice.

APPROACH AND RESULTS

Lethally irradiated low-density lipoprotein receptor-deficient mice (Ldlr^-/-) were reconstituted with bone marrow from either wild-type or mitochondrial catalase (mCAT) mice. mCAT transgenic mice contain ectopically expressed human catalase gene in mitochondria, which reduces mitoOS. Starting at the age of 36 weeks, mice were fed the Western-type diet for 16 weeks. We found that mitoOS in lesional myeloid cells was suppressed in aged mCAT→Ldlr^-/- chimeric mice compared with aged controls, and this led to a significant reduction in aortic root atherosclerotic lesion area despite higher plasma cholesterol levels. Neutrophil extracellular traps (NETs), a proinflammatory extracellular structure that contributes to atherosclerosis progression, were significantly increased in the lesions of aged mice compared with lesions of younger mice. Aged mCAT→Ldlr^-/- mice had less lesional neutrophils and decreased NETs compared with age-matched wild-type→Ldlr^-/- mice, whereas young mCAT→ and wild-type→Ldlr^-/- mice had comparable numbers of neutrophils and similar low levels of lesional NETs. Using cultured neutrophils, we showed that suppression of mitoOS reduced 7-ketocholesterol-induced NET release from neutrophils of aged but not younger mice.

CONCLUSIONS

MitoOS in lesional myeloid cells enhanced atherosclerosis development in aged mice, and this enhancement was associated with increased lesional NETs. Thus, mitoOS-induced NET formation is a potentially new therapeutic target to prevent atherosclerosis progression during aging.

[Phylogenetic signal at the Cytb-SertRNA-IG1-ND1 mitochondrial region in Anopheles (Kerteszia) neivai Howard, Dyar & Knab, 1913]

INTRODUCTION

Mitochondrial DNA has proven its utility for the study of insect evolution. Genes such as cytochrome b (Cytb) and the transfer gene for serine (SertRNA) can be used to compare closely related organisms.

OBJECTIVE

The phylogenetic utility of Cytb-SertRNA-IG1-ND1 was tested for polymorphisms, and secondary structure modeling in SertRNA was done to detect possible cryptic species in Anopheles neivai.

MATERIALS AND METHODS

Specimens from Colombia, Guatemala, and the type locality in Panamá were collected and sequenced for specimen comparison based on DNA polymorphisms, and secondary structure modeling for the SertRNA gene.

RESULTS

Thirty-six sequences for A. neivai and A. pholidotus were obtained.

CONCLUSIONS

Polymorphic variants were detected in A. neivai for Cytb-SertRNA-IG1- ND1. Despite this variation in A. neivai, cryptic species could not be detected.

STING-IRF3 Triggers Endothelial Inflammation in Response to Free Fatty Acid-Induced Mitochondrial Damage in Diet-Induced Obesity

OBJECTIVE

Metabolic stress in obesity induces endothelial inflammation and activation, which initiates adipose tissue inflammation, insulin resistance, and cardiovascular diseases. However, the mechanisms underlying endothelial inflammation induction are not completely understood. Stimulator of interferon genes (STING) is an important molecule in immunity and inflammation. In the present study, we sought to determine the role of STING in palmitic acid-induced endothelial activation/inflammation.

APPROACH AND RESULTS

In cultured endothelial cells, palmitic acid treatment activated STING, as indicated by its perinuclear translocation and binding to interferon regulatory factor 3 (IRF3), leading to IRF3 phosphorylation and nuclear translocation. The activated IRF3 bound to the promoter of ICAM-1 (intercellular adhesion molecule 1) and induced ICAM-1 expression and monocyte-endothelial cell adhesion. When analyzing the upstream signaling, we found that palmitic acid activated STING by inducing mitochondrial damage. Palmitic acid treatment caused mitochondrial damage and leakage of mitochondrial DNA into the cytosol. Through the cytosolic DNA sensor cGAS (cyclic GMP-AMP synthase), the mitochondrial damage and leaked cytosolic mitochondrial DNA activated the STING-IRF3 pathway and increased ICAM-1 expression. In mice with diet-induced obesity, the STING-IRF3 pathway was activated in adipose tissue. However, STING deficiency (Sting^gt/gt ) partially prevented diet-induced adipose tissue inflammation, obesity, insulin resistance, and glucose intolerance.

CONCLUSIONS

The mitochondrial damage-cGAS-STING-IRF3 pathway is critically involved in metabolic stress-induced endothelial inflammation. STING may be a potential therapeutic target for preventing cardiovascular diseases and insulin resistance in obese individuals.

Endothelial Cell Bioenergetics and Mitochondrial DNA Damage Differ in Humans Having African or West Eurasian Maternal Ancestry

BACKGROUND

We hypothesized that endothelial cells having distinct mitochondrial genetic backgrounds would show variation in mitochondrial function and oxidative stress markers concordant with known differential cardiovascular disease susceptibilities. To test this hypothesis, mitochondrial bioenergetics were determined in endothelial cells from healthy individuals with African versus European maternal ancestries.

METHODS AND RESULTS

Bioenergetics and mitochondrial DNA (mtDNA) damage were assessed in single-donor human umbilical vein endothelial cells belonging to mtDNA haplogroups H and L, representing West Eurasian and African maternal ancestries, respectively. Human umbilical vein endothelial cells from haplogroup L used less oxygen for ATP production and had increased levels of mtDNA damage compared with those in haplogroup H. Differences in bioenergetic capacity were also observed in that human umbilical vein endothelial cells belonging to haplogroup L had decreased maximal bioenergetic capacities compared with haplogroup H. Analysis of peripheral blood mononuclear cells from age-matched healthy controls with West Eurasian or African maternal ancestries showed that haplogroups sharing an A to G mtDNA mutation at nucleotide pair 10398 had increased mtDNA damage compared with those lacking this mutation. Further study of angiographically proven patients with coronary artery disease and age-matched healthy controls revealed that mtDNA damage was associated with vascular function and remodeling and that age of disease onset was later in individuals from haplogroups lacking the A to G mutation at nucleotide pair 10398.

CONCLUSIONS

Differences in mitochondrial bioenergetics and mtDNA damage associated with maternal ancestry may contribute to endothelial dysfunction and vascular disease.

Mitochondrial DNA Haplogroups and Neurocognitive Impairment During HIV Infection

BACKGROUND

Neurocognitive impairment (NCI) remains an important complication in persons infected with human immunodeficiency virus (HIV). Ancestry-related mitochondrial DNA (mtDNA) haplogroups have been associated with outcomes of HIV infection and combination antiretroviral therapy (CART), and with neurodegenerative diseases. We hypothesize that mtDNA haplogroups are associated with NCI in HIV-infected adults and performed a genetic association study in the CNS HIV Antiretroviral Therapy Effects Research (CHARTER) cohort.

METHODS

CHARTER is an observational study of ambulatory HIV-infected adults. Haplogroups were assigned using mtDNA sequence, and principal components were derived from ancestry-informative nuclear DNA variants. Outcomes were cross-sectional global deficit score (GDS) as a continuous measure, GDS impairment (GDS ≥ 0.50), and HIV-associated neurocognitive disorder (HAND) using international criteria. Multivariable models were adjusted for comorbidity status (incidental vs contributing), current CART, plasma HIV RNA, reading ability, and CD4 cell nadir.

RESULTS

Haplogroups were available from 1027 persons; median age 43 years, median CD4 nadir 178 cells/mm(3), 72% on CART, and 46% with HAND. The 102 (9.9%) persons of genetically determined admixed Hispanic ancestry had more impairment by GDS or HAND than persons of European or African ancestry (P < .001 for all). In multivariate models including persons of admixed Hispanic ancestry, those with haplogroup B had lower GDS (β = -0.34; P = .008) and less GDS impairment (odds ratio = 0.16; 95% confidence interval, .04, .63; P = .009) than other haplogroups. There were no significant haplogroup associations among persons of European or African ancestry.

CONCLUSIONS

In these mostly CART-treated persons, mtDNA haplogroup B was associated with less NCI among persons of genetically determined Hispanic ancestry. mtDNA variation may represent an ancestry-specific factor influencing NCI in HIV-infected persons.

Divergent mitochondrial biogenesis responses in human cardiomyopathy

BACKGROUND

Mitochondria are key players in the development and progression of heart failure (HF). Mitochondrial (mt) dysfunction leads to diminished energy production and increased cell death contributing to the progression of left ventricular failure. The fundamental mechanisms that underlie mt dysfunction in HF have not been fully elucidated.

METHODS AND RESULTS

To characterize mt morphology, biogenesis, and genomic integrity in human HF, we investigated left ventricular tissue from nonfailing hearts and end-stage ischemic (ICM) or dilated (DCM) cardiomyopathic hearts. Although mt dysfunction was present in both types of cardiomyopathy, mt were smaller and increased in number in DCM compared with ICM or nonfailing hearts. mt volume density and mtDNA copy number was increased by ≈2-fold (P<0.001) in DCM hearts in comparison with ICM hearts. These changes were accompanied by an increase in the expression of mtDNA-encoded genes in DCM versus no change in ICM. mtDNA repair and antioxidant genes were reduced in failing hearts, suggestive of a defective repair and protection system, which may account for the 4.1-fold increase in mtDNA deletion mutations in DCM (P<0.05 versus nonfailing hearts, P<0.05 versus ICM).

CONCLUSIONS

In DCM, mt dysfunction is associated with mtDNA damage and deletions, which could be a consequence of mutating stress coupled with a peroxisome proliferator-activated receptor γ coactivator 1α-dependent stimulus for mt biogenesis. However, this maladaptive compensatory response contributes to additional oxidative damage. Thus, our findings support further investigations into novel mechanisms and therapeutic strategies for mt dysfunction in DCM.