Mitochondrial DNA haplogroups and short-term neurological outcomes of ischemic stroke

Genetics of ischemic stroke functional outcome

Ischemic stroke, which accounts for 87% of cerebrovascular accidents, is responsible for massive global burden both in terms of economic cost and personal hardship. Many stroke survivors face long-term disability-a phenotype associated with an increasing number of genetic variants. While clinical variables such as stroke severity greatly impact recovery, genetic polymorphisms linked to functional outcome may offer physicians a unique opportunity to deliver personalized care based on their patient's genetic makeup, leading to improved outcomes. A comprehensive catalogue of the variants at play is required for such an approach. In this review, we compile and describe the polymorphisms associated with outcome scores such as modified Rankin Scale and Barthel Index. Our search identified 74 known genetic polymorphisms spread across 48 features associated with various poststroke disability metrics. The known variants span diverse biological systems and are related to inflammation, vascular homeostasis, growth factors, metabolism, the p53 regulatory pathway, and mitochondrial variation. Understanding how these variants influence functional outcome may be helpful in maximizing poststroke recovery.

Influence of the rs6736 Polymorphism on Ischemic Stroke Susceptibility in Han Chinese Individuals via the Disruption of miR-7-1 Binding to the C14orf119 Gene

This study investigates the association between the C14orf119 gene rs6736 polymorphism and ischemic stroke (IS) susceptibility, and explores the influence of the rs6736 polymorphism on the binding between miR-7-1 and the C14orf119 gene. mRNA expression levels were determined in 45 IS patients and 45 matched controls via real-time quantitative PCR. A total of 774 IS patients and 793 matched controls were recruited from a Han Chinese population for genotyping, performed with the Sequenom MassARRAY iPLEX platform. A dual-luciferase reporter assay was used for the analysis of miRNA-mRNA binding. The results showed that the mRNA expression of C14orf119 differed significantly between IS patients and controls (t =  -2.235, P = 0.030). Significant associations were noted between the C14orf119 gene rs6736 polymorphism and IS susceptibility in Han Chinese individuals under the additive model [OR_adj (95% CI) = 0.87 (0.76-1.00) P_adj = 0.048] and dominant model [OR_adj (95% CI) = 0.76 (0.61-0.94), P_adj = 0.014], with adjustment for age and sex. Mutations in the rs6736 polymorphism disrupted the binding of miR-7-1 and the C14orf119 gene. The results of this study show that the rs6736 polymorphism in the 3'-untranslated region of the C14orf119 gene not only is associated with IS but also modifies the binding between miR-7-1 and the C14orf119 gene. The C14orf119 gene may participate in the relationship between IS and miR-7-1.

Targeting the gasdermin D as a strategy for ischemic stroke therapy

Stroke is a major cause of death and disability worldwide that triggers a variety of neuropathological conditions, leading to the initiation of several pro-inflammatory mediators and neuronal damage. Neuroinflammation has been considered the potential therapeutic target and contributes to the pathology of ischemia and reperfusion. Pyroptosis is an inflammatory form of programmed cell death that plays an important role in immune protection against stroke. Gasdermin D (GSDMD) is the final executor of pyroptosis upon cleavage by caspases-1/4/5/11, followed by canonical and noncanonical inflammasome activation, leading to a series of inflammatory responses. GSDMD N-terminal domain assembles plasma membrane as well as organelle membrane pores to induce cytolysis, thereby triggering cytokine release and inflammatory-related cell death. In our review, we concisely summarized and highlighted the potential role of GSDMD-regulated pyroptosis and the biological characteristic of GSDMD as a therapeutic target in ischemic stroke. A better understanding of the roles of GSDMD may provide a theoretical basis for the design of novel therapeutic interventions for the treatment of ischemic stroke.

Ischemic Stroke Risk Associated with Mitochondrial Haplogroup F in the Asian Population

Mitochondrial dysfunction is involved in the pathogenesis of atherosclerosis, the primary risk factor for ischemic stroke. This study aims to explore the role of mitochondrial genomic variations in ischemic stroke, and to uncover the nuclear genes involved in this relationship. Eight hundred and thirty Taiwanese patients with a history of ischemic stroke and 966 normal controls were genotyped for their mitochondrial haplogroup (Mthapg). Cytoplasmic hybrid cells (cybrids) harboring different Mthapgs were used to observe functional differences under hypoxia-ischemia. RNA sequencing (RNASeq) was conducted to identify the particularly elevated mRNA. The patient study identified an association between Mthapg F1 and risk of ischemic stroke (OR 1.72:1.27-2.34, p = 0.001). The cellular study further demonstrated an impeded induction of hypoxic inducible factor 1α in the Mthapg F1 cybrid after hypoxia-ischemia. Additionally, the study demonstrated that Mthapg F cybrids were associated with an altered mitochondrial function, including decreased oxygen consumption, higher mitochondrial ROS production, and lower mitochondrial membrane potential. Mthapg F cybrids were also noted to be prone to inflammation, with increased expression of several inflammatory cytokines and elevated matrix metalloproteinase 9. The RNASeq identified significantly elevated expressions of angiopoietin-like 4 in Mthapg F1 cybrids after hypoxia-ischemia. Our study demonstrates an association between Mthapg F and susceptibility to ischemic stroke.

Use of plasma mitochondrial DNA levels for determining disease severity and prognosis in pediatric sepsis: a case control study

BACKGROUND

The mortality rate due to severe sepsis is approximately 30-60%. Sepsis readily progresses to septic shock and multiple organ dysfunction, representing a significant problem in the pediatric intensive care unit (PICU). The aim of this study was to explore the value of plasma mitochondrial DNA (mtDNA) for early diagnosis and prognosis in children with sepsis.

METHODS

A total of 123 children with sepsis who were hospitalized in the Hunan Children's Hospital PICU from July 2013 to December 2014 were divided into the general sepsis group (n = 70) and severe sepsis group (n = 53) based on diagnostic standards. An additional 30 children with non-sepsis infection and 30 healthy children were randomly selected as a control group. Patients' plasma was collected during admission to the PICU. A pediatric critical illness score (PCIS) was also calculated. The plasma mtDNA level was examined using real-time polymerase chain reaction technology, and other parameters including routine laboratory values; blood lactate, procalcitonin (PCT), and C-reactive protein (CRP) levels; and data on survival were collected and compared among the groups.

RESULTS

The plasma mtDNA level in the sepsis group than that in the non-sepsis infection and healthy groups. The plasma mtDNA level was significantly higher in the severe sepsis than in the general sepsis group (p < 0.001). A lower PCIS was associated with a higher plasma mtDNA level (p < 0.001). A higher number of organs with dysfunction was associated with higher plasma mtDNA levels (p < 0.001). Plasma mtDNA levels were higher among patients with elevated alanine aminotransferase, aspartate aminotransferase, blood urea nitrogen, creatinine, lactate dehydrogenase, creatine kinase, myoglobin, creatine kinase MB, and troponin than in those with values within the normal range. The mtDNA level was higher among non-survivors than among survivors, and this difference was significant. mtDNA showed a prognostic prediction value similar to that of lactate, PCT, and CRP.

CONCLUSIONS

Plasma mtDNA levels may be a suitable biomarker for diagnosis and prognosis in children with sepsis.

Involvement of mitochondrial haplogroups in myocardial infarction and stroke: A case-control study in Castile and Leon (Spain) population

There are strong evidences that common mitochondrial DNA (mtDNA) haplogroups may influence the pathogenesis of cardiovascular diseases (CVDs). In this matched case-control study, we investigate the association between mtDNA haplogroups and two CVDs, myocardial infarction (MI) and stroke, and classical cardiovascular risk factors. Data obtained show that haplogroup H constitute a susceptibility risk factor for MI (p=0.001; OR=2.379, 95% CI [1.440-3.990]). Otherwise, our data also suggest a beneficial role of haplogroup J against hypertension (p=0.019; OR=0.348, 95% CI [0.144-0.840]). These results may provide some guidance for predicting the genetic risk of these diseases in different human populations through the differences in energy efficiency between haplogroups.