Valproic acid triggers increased mitochondrial biogenesis in POLG-deficient fibroblasts

Brazilian experts' consensus on the treatment of infantile epileptic spasm syndrome in infants

BACKGROUND

Infantile epileptic spasms syndrome (IESS) is a rare but severe condition affecting children early and is usually secondary to an identifiable brain disorder. It is related to psychomotor deterioration in childhood and epilepsy in adult life. Treatment is challenging as infantile spasms may not respond to most antiseizure medication, and relapse is frequent.

OBJECTIVE

To evaluate the literature regarding treatment of IESS and provide a practical guidance to a healthcare system with limited resources.

METHODS

An expert committee from the Brazilian Society of Child Neurology reviewed and discussed relevant scientific evidence in the treatment of IESS regarding the drugs available in Brazil.

RESULTS

Oral prednisolone and vigabatrin are the most common drugs used as first-line therapy; they are efficient and affordable therapy as both are available in the Brazilian unified health system (SUS, in the Portuguese acronym). Intramuscular adrenocorticotropic hormone (ACTH) presents similar efficacy as oral prednisolone but has a higher cost and is not available in Brazil. Other antiseizure medications such as topiramate, levetiracetam, or benzodiazepines have limited response and are prescribed as adjuvant therapy. If the health service has nutritionists, a ketogenic diet should be implemented for those not responding to hormonal and vigabatrin treatment. Epilepsy surgery is mainly indicated for patients with focal lesions that do not respond to pharmacological therapy.

CONCLUSION

Early treatment of IESS with efficient drugs is feasible in our country. Using standard protocols increases the odds of achieving complete cessation in a shorter time and decreases relapse.

Mitochondrial Toxic Effects of Antiepileptic Drug Valproic Acid on Mouse Kidney Stem Cells

Valproic acid (VPA) is a histone deacetylase inhibitor that is used mainly as an antiepileptic and anticonvulsant drug. The side effects of VPA usually appears as hepatic injury and various metabolic disorders. On the other hand, it is rarely reported to cause kidney injury. Despite the many studies on the influence of VPA exposure on the kidneys, the specific mechanism remains unclear. This study examined the changes after VPA treatment to the mouse kidney stem cells (mKSCs). VPA triggers an increase in mitochondrial ROS, but there was no change in either mitochondrial membrane potential or the mitochondrial DNA copy number in mKSCs. The VPA treatment increased the mitochondrial complex III but decreased complex V significantly compared to the DMSO treatment as a control. The inflammatory marker (IL-6) and the expression of the apoptosis markers (Caspase 3) and were increased by VPA. In particular, the expression of the podocyte injury markers (CD2AP) was increased significantly. In conclusion, VPA exposure has adverse effects on mouse kidney stem cells.

Metabolic plasticity in blast crisis-chronic myeloid leukaemia cells under hypoxia reduces the cytotoxic potency of drugs targeting mitochondria

Metabolic reprogramming (MR) influences progression of chronic myeloid leukaemia (CML) to blast crisis (BC), but metabolic programs may change transiently in a second dimension (metabolic plasticity, MP), driven by environments as hypoxia, affecting cytotoxic potency (CPot) of drugs targeting mitochondria or mitochondria-related cell stress responses (MRCSR) such as mitophagy and mitochondrial biogenesis. We assessed mitochondrial membrane potential (MMP), mitochondrial mass (MM), apoptosis, glucose uptake (GU), and CPot of arsenic trioxide (ATO), CCCP, valproic acid (VPA), vincristine (VCR), Mdivi1, and dichloroacetic acid (DCA) in CML BC cells K562 (BC-K562) under hypoxia through flow cytometry, and gene expression from GEO database. About 60% of untreated cells were killed after 72 h under hypoxia, but paradoxically, all drugs but ATO rescued cells and increased survival rates to almost 90%. Blocking mitophagy either with VCR or Mdivi1, or increasing mitochondrial biogenesis with VPA enhanced cell-survival with increased MM. DCA increased MM and rescued cells in spite of its role in activating pyruvate dehydrogenase and Krebs cycle. Cells rescued by DCA, VPA and CCCP showed decreased GU. ATO showed equal CPot in hypoxia and normoxia. MP was evidenced by differential expression of genes (DEG) under hypoxia related to Krebs cycle, lipid synthesis, cholesterol homeostasis, mitophagy, and mitochondrial biogenesis (GSE144527). A 25-gene MP-signature of BC-K562 cells under hypoxia identified BC cases among 113 transcriptomes from CML patients (GSE4170). We concluded that hypoxic environment drove a MP change evidenced by DEG that was reflected in a paradoxical pro-survival, instead of cytotoxic, effect of drugs targeting mitochondria and MRCSR.

Long-term use of valproic acid reduced mortality in bipolar disorder patients in a Taiwanese population: An association analysis using the national health insurance research database (NHIRD)

OBJECTIVE

Valproic acid (VPA) is used for the treatment of epilepsy and bipolar disorder (BD). The aims of this study was to examine that long-term VPA use affects mortality in BD patients.

METHODS

Association analysis was conducted using the National Health Insurance Research Database (NHIRD) of Taiwan. The long-term VPA use group was selected as patients treated with VPA for BD who used VPA only. The control group consisted of BD patients who were not treated with VPA or lithium. The lithium use group consisted by BD patients used lithium only was also joined the analysis. The cofactors included age (>65 years), sex and the Charlson Comorbidity Index.

RESULTS

The hazard ratio (HR) of mortality for the VPA group was 0.83 (95% confidence interval (CI), (0.70-0.99); P = 0.04) and the result of lithium group did not reach statistical significance. Furthermore only the duration> 3 years subgroup had a significantly lower incidence of mortality than the control group, with an HR of 0.54 (95% CI, (0.42-0.70); P < 0.001) and 0.58 (95% CI, (0.38, 0.89); P = 0.013 in VPA and lithium groups, respectively. The effect of VPA treatment in terms of reducing the risk of mortality was evidenced only in the male population and the <65 years subgroup (HR: 0.75; 95% CI, (0.59-0.95), and 0.78; 95% CI, (0.64-0.96), respectively). The major limitation of this study was that the causes of death of the expired subjects were not available.

CONCLUSION

Long-term VPA use decreases the risk of mortality in BD patients, especially in the male population and those aged <65 years.

DNA Polymerase Gamma Recovers Mitochondrial Function and Inhibits Vascular Calcification by Interacted with p53

DNA polymerase gamma (PolG) is the major polymerase of mitochondrial DNA (mtDNA) and essential for stabilizing mitochondrial function. Vascular calcification (VC) is common senescence related degenerative pathology phenomenon in the end-stage of multiple chronic diseases. Mitochondrial dysfunction was often observed in calcified vessels, but the function and mechanism of PolG in the calcification process was still unknown. The present study found PolG^D257A/D257A mice presented more severe calcification of aortas than wild type (WT) mice with vitamin D3 (Vit D3) treatment, and this phenomenon was also confirmed in vitro. Mechanistically, PolG could enhance the recruitment and interaction of p53 in calcification condition to recover mitochondrial function and eventually to resist calcification. Meanwhile, we found the mutant PolG (D257A) failed to achieve the same rescue effects, suggesting the 3'-5' exonuclease activity guarantee the enhanced interaction of p53 and PolG in response to calcification stimulation. Thus, we believed that it was PolG, not mutant PolG, could maintain mitochondrial function and attenuate calcification in vitro and in vivo. And PolG could be a novel potential therapeutic target against calcification, providing a novel insight to clinical treatment.

Mitochondrial DNA Copy Number Is Associated With Treatment Response and Cognitive Function in Euthymic Bipolar Patients Receiving Valproate

BACKGROUND

Bipolar disorder (BD) is associated with cognitive impairment and mitochondrial dysfunction. However, the associations among mitochondrial DNA copy number (MCN), treatment response, and cognitive function remain elusive in BD patients.

METHODS

Sixty euthymic BD patients receiving valproate (VPA) and 66 healthy controls from the community were recruited. The indices of metabolic syndrome (MetS) were measured. Quantitative polymerase chain reaction analysis of blood leukocytes was used to measure the MCN. Cognitive function was measured by calculating perseverative errors and completed categories on the Wisconsin Card Sorting Test (WCST). The VPA treatment response was measured using the Alda scale.

RESULTS

BD patients had significantly higher MCN, triglyceride, and C-reactive protein (CRP) levels, waist circumference, and worse performance on the WCST than the controls. Regression models showed that BD itself and the VPA concentration exerted significant effects on increased MCN levels. Moreover, the receiver operating characteristic curve analysis showed that an MCN of 2.05 distinguished VPA responders from nonresponders, with an area under the curve of 0.705 and a sensitivity and specificity of 0.529 and 0.816, respectively. An MCN level ≥2.05 was associated with 5.39 higher odds of being a VPA responder (P = .006). BD patients who were stratified into the high-MCN group had a higher VPA response rate, better WCST performance, lower CRP level, and less MetS.

CONCLUSIONS

The study suggests a link between the peripheral MCN and cognitive function in BD patients. As an inflammatory status, MetS might modulate this association.

Differences in mitochondrial DNA copy number between patients with bipolar I and II disorders

Mitochondria play a critical role in energy metabolism. Genetic, postmortem brain, and brain imaging studies of bipolar disorder (BD) patients indicated that mitochondrial dysfunction might explain BD pathophysiology. Mitochondrial function can be indirectly evaluated by measuring mitochondrial DNA (mtDNA) copy numbers. We recruited 186 bipolar I disorder (BD1) and 95 bipolar II disorder (BD2) patients, and age- and sex-matched controls. MtDNA copy numbers in peripheral blood cells were measured via quantitative polymerase chain reaction. We explored parameters (including age and clinical features) that might affect mtDNA copy numbers. We found that BD1 patients had a lower mtDNA copy number than controls and that mtDNA copy number was negatively associated with the number of mood episodes. BD2 patients had a higher mtDNA copy number than controls. Thus, changes in mitochondrial function may influence BD pathophysiology. The opposite directions of the association with mtDNA copy number in BD1 and BD2 patients suggests that the difference in pathophysiology may be associated with mitochondrial function.

Mitochondrial hepatopathy: Respiratory chain disorders- ‘breathing in and out of the liver’

Mitochondria, the powerhouse of a cell, are closely linked to the pathophysiology of various common as well as not so uncommon disorders of the liver and beyond. Evolution supports a prokaryotic descent, and, unsurprisingly, the organelle is worthy of being labeled an organism in itself. Since highly metabolically active organs require a continuous feed of energy, any dysfunction in the structure and function of mitochondria can have variable impact, with the worse end of the spectrum producing catastrophic consequences with a multisystem predisposition. Though categorized a hepatopathy, mitochondrial respiratory chain defects are not limited to the liver in time and space. The liver involvement is also variable in clinical presentation as well as in age of onset, from acute liver failure, cholestasis, or chronic liver disease. Other organs like eye, muscle, central and peripheral nervous system, gastrointestinal tract, hematological, endocrine, and renal systems are also variably involved. Diagnosis hinges on recognition of subtle clinical clues, screening metabolic investigations, evaluation of the extra-hepatic involvement, and role of genetics and tissue diagnosis. Treatment is aimed at both circumventing the acute metabolic crisis and long-term management including nutritional rehabilitation. This review lists and discusses the burden of mitochondrial respiratory chain defects, including various settings when to suspect, their evolution with time, including certain specific disorders, their tiered evaluation with diagnostic algorithms, management dilemmas, role of liver transplantation, and the future research tools.

Efficacy of Cicuta virosa medicinal preparations against pentylenetetrazole-induced seizures

Epileptic seizures are characterized by imbalanced inhibition-excitation cycle that triggers biochemical alterations responsible for jeopardized neuronal integrity. Conventional antiepileptic drugs (AEDs) have been the mainstay option for treatment and control; however, symptomatic control and potential to exacerbate the seizure condition calls for viable alternative to these chemical agents. In this context, natural product-based therapies have accrued great interest in recent years due to competent disease management potential and lower associated adversities. Cicuta virosa (CV) is one such herbal remedy that is used in traditional system of medicine against myriad of disorders including epilepsy. Homeopathic medicinal preparations (HMPs) of CV were assessed for their efficacy in pentylenetetrazole (PTZ)-induced acute and kindling models of epilepsy. CV HMPs increased the latency and reduced the duration of tonic-clonic phase in acute model while lowering the kindling score in the kindling model that signified their role in modulating GABAergic neurotransmission and potassium conductance. Kindling-induced impairment of cognition, memory, and motor coordination was ameliorated by the CV HMPs that substantiated their efficacy in imparting sustained neuronal fortification. Furthermore, biochemical evaluation showed attenuated oxidative stress load through reduced lipid peroxidation and strengthened free radical scavenging mechanism. Taken together, CV HMPs exhibited promising results in acute and kindling models and must be further assessed through molecular and epigenomic studies.

Accelerated hippocampal biological aging in bipolar disorder

OBJECTIVES

Evidence suggests accelerated aging mechanisms in bipolar disorder (BD), including DNA methylation (DNAm) aging in blood. However, it is unknown whether such mechanisms are also evident in the brain, in particular in association with other biological clocks. To investigate this, we interrogated genome-wide DNAm in postmortem hippocampus from 32 BD-I patients and 32 non-psychiatric controls group-matched for age and sex from the NIMH Human Brain Collection Core.

METHODS

DNAm age and epigenetic aging acceleration were estimated using the Horvath method. Telomere length (TL) and mitochondrial DNA (mtDNA) copy number were quantified by real-time PCR. Between-group differences were assessed by linear regression and univariate general linear models with age, sex, race, postmortem interval, tissue pH, smoking, and body mass index included as co-variates.

RESULTS

Groups did not differ for epigenetic aging acceleration when considering the entire sample. However, after splitting the sample by the median age, an epigenetic aging acceleration was detected in patients compared to controls among older subjects (P = .042). While TL did not differ between groups, a reduction in mtDNA copy number was observed in patients compared to controls (P = .047). In addition, significant correlations were observed between epigenetic aging acceleration and TL (r = -.337, P = .006), as well as between TL and mtDNA copy number (r = .274, P = .028).

CONCLUSIONS

Hippocampal aging may underlie neurocognitive dysfunctions observed in BD patients. Moreover, our results suggest a complex cross-talk between biological clocks in hippocampus that may underlie clinical manifestations of premature aging in BD.

Discovery of the First Vitamin K Analogue as a Potential Treatment of Pharmacoresistant Seizures

Despite the availability of more than 25 antiseizure drugs on the market, approximately 30% of patients with epilepsy still suffer from seizures. Thus, the epilepsy therapy market has a great need for a breakthrough drug that will aid pharmacoresistant patients. In our previous study, we discovered a vitamin K analogue, 2h, which displayed modest antiseizure activity in zebrafish and mouse seizure models. However, there are limitations to this compound due to its pharmacokinetic profile. In this study, we develop a new series of vitamin K analogues by modifying the structure of 2h. Among these, compound 3d shows full protection in a rodent pharmacoresistant seizure model with limited rotarod motor toxicity and favorable pharmacokinetic properties. Furthermore, the brain/plasma concentration ratio of 3d indicates its excellent permeability into the brain. The resulting data shows that 3d can be further developed as a potential antiseizure drug in the clinic.

A drug potency signature links progression of chronic lymphocytic leukemia to mitochondria-related stress responses and metabolic reprogramming under hypoxia

Chronic lymphocytic leukemia (CLL) cells change their metabolic program between normoxia and hypoxia, possibly affecting cytotoxic drug potency by altering mitochondria-related cell stress responses (MRCSR) including mitophagy, mitochondrial biogenesis, and mitochondrial proteostasis. We evaluated in CLL cells from nine patients, the single and multiple-combined drug potency of arsenic trioxide (ATO), valproic acid (VPA), vincristine (VCR) and MG132 as four pharmacological sensors influencing mitochondrial apoptosis, mitochondrial biogenesis, mitophagy, and mitochondrial proteostasis respectively, under normoxia and hypoxia to force hypoxia-induced metabolic reprogramming (HMR). Untreated cells from all patients remained viable under O₂ levels below 0.5% for 72 h. We obtained 21 measures of drug potency and interaction at 50% effect level that we denoted drug potency signature (DPS). Using the comparative DPS between normoxia and hypoxia, two non-supervised classification algorithms discriminated CLL patients with active disease (ADT) and stable disease (NAD) and showed complete consistency with their clinical characteristics. In ADT group under hypoxia, the potency of MG132 was increased, the interaction of ATO + VPA and ATO + VPA + VCR shifted towards antagonism, and ATO + VPA + VCR + MG132 shifted towards synergism, indicating a prominent role of mitochondrial proteostasis. Classification of patients based on DPS, depended on the contrasting response of drugs under hypoxia and normoxia, owing to HMR. Using these drugs as pharmacological sensors, we linked the metabolic arrangement of CLL cells under hypoxia, to potency of drugs targeting MRCSR, and to the clinical features of individual patients, therefore providing new sources of data on disease progression, drug response and risk prognosis.

Valproic Acid and the Liver Injury in Patients with Epilepsy: An Update

BACKGROUND

Valproic acid (VPA) as a widely used primary medication in the treatment of epilepsy is associated with reversible or irreversible hepatotoxicity. Long-term VPA therapy is also related to increased risk for the development of non-alcoholic fatty liver disease (NAFLD). In this review, metabolic elimination pathways of VPA in the liver and underlying mechanisms of VPA-induced hepatotoxicity are discussed.

METHODS

We searched in PubMed for manuscripts published in English, combining terms such as "Valproic acid", "hepatotoxicity", "liver injury", and "mechanisms". The data of screened papers were analyzed and summarized.

RESULTS

The formation of VPA reactive metabolites, inhibition of fatty acid β-oxidation, excessive oxidative stress and genetic variants of some enzymes, such as CPS1, POLG, GSTs, SOD2, UGTs and CYPs genes, have been reported to be associated with VPA hepatotoxicity. Furthermore, carnitine supplementation and antioxidants administration proved to be positive treatment strategies for VPA-induced hepatotoxicity.

CONCLUSION

Therapeutic drug monitoring (TDM) and routine liver biochemistry monitoring during VPA-therapy, as well as genotype screening for certain patients before VPA administration, could improve the safety profile of this antiepileptic drug.

Regulation of Inositol Biosynthesis: Balancing Health and Pathophysiology

Inositol is the precursor for all inositol compounds and is essential for viability of eukaryotic cells. Numerous cellular processes and signaling functions are dependent on inositol compounds, and perturbation of their synthesis leads to a wide range of human diseases. Although considerable research has been directed at understanding the function of inositol compounds, especially phosphoinositides and inositol phosphates, a focus on regulatory and homeostatic mechanisms controlling inositol biosynthesis has been largely neglected. Consequently, little is known about how synthesis of inositol is regulated in human cells. Identifying physiological regulators of inositol synthesis and elucidating the molecular mechanisms that regulate inositol synthesis will contribute fundamental insight into cellular processes that are mediated by inositol compounds and will provide a foundation to understand numerous disease processes that result from perturbation of inositol homeostasis. In addition, elucidating the mechanisms of action of inositol-depleting drugs may suggest new strategies for the design of second-generation pharmaceuticals to treat psychiatric disorders and other illnesses.

The metabolic face of migraine - from pathophysiology to treatment

Migraine can be regarded as a conserved, adaptive response that occurs in genetically predisposed individuals with a mismatch between the brain's energy reserve and workload. Given the high prevalence of migraine, genotypes associated with the condition seem likely to have conferred an evolutionary advantage. Technological advances have enabled the examination of different aspects of cerebral metabolism in patients with migraine, and complementary animal research has highlighted possible metabolic mechanisms in migraine pathophysiology. An increasing amount of evidence - much of it clinical - suggests that migraine is a response to cerebral energy deficiency or oxidative stress levels that exceed antioxidant capacity and that the attack itself helps to restore brain energy homeostasis and reduces harmful oxidative stress levels. Greater understanding of metabolism in migraine offers novel therapeutic opportunities. In this Review, we describe the evidence for abnormalities in energy metabolism and mitochondrial function in migraine, with a focus on clinical data (including neuroimaging, biochemical, genetic and therapeutic studies), and consider the relationship of these abnormalities with the abnormal sensory processing and cerebral hyper-responsivity observed in migraine. We discuss experimental data to consider potential mechanisms by which metabolic abnormalities could generate attacks. Finally, we highlight potential treatments that target cerebral metabolism, such as nutraceuticals, ketone bodies and dietary interventions.

Mitochondria, Metabolism, and Redox Mechanisms in Psychiatric Disorders

Significance: Our current knowledge of the pathophysiology and molecular mechanisms causing psychiatric disorders is modest, but genetic susceptibility and environmental factors are central to the etiology of these conditions. Autism, schizophrenia, bipolar disorder and major depressive disorder show genetic gene risk overlap and share symptoms and metabolic comorbidities. The identification of such common features may provide insights into the development of these disorders. Recent Advances: Multiple pieces of evidence suggest that brain energy metabolism, mitochondrial functions and redox balance are impaired to various degrees in psychiatric disorders. Since mitochondrial metabolism and redox signaling can integrate genetic and environmental environmental factors affecting the brain, it is possible that they are implicated in the etiology and progression of psychiatric disorders. Critical Issue: Evidence for direct links between cellular mitochondrial dysfunction and disease features are missing. Future Directions: A better understanding of the mitochondrial biology and its intracellular connections to the nuclear genome, the endoplasmic reticulum and signaling pathways, as well as its role in intercellular communication in the organism, is still needed. This review focuses on the findings that implicate mitochondrial dysfunction, the resultant metabolic changes and oxidative stress as important etiological factors in the context of psychiatric disorders. We also propose a model where specific pathophysiologies of psychiatric disorders depend on circuit-specific impairments of mitochondrial dysfunction and redox signaling at specific developmental stages.

Potential Protective Mechanisms of Ketone Bodies in Migraine Prevention

An increasing amount of evidence suggests that migraines are a response to a cerebral energy deficiency or oxidative stress levels that exceed antioxidant capacity. The ketogenic diet (KD), a diet mimicking fasting that leads to the elevation of ketone bodies (KBs), is a therapeutic intervention targeting cerebral metabolism that has recently shown great promise in the prevention of migraines. KBs are an alternative fuel source for the brain, and are thus likely able to circumvent some of the abnormalities in glucose metabolism and transport found in migraines. Recent research has shown that KBs-D-β-hydroxybutyrate in particular-are more than metabolites. As signalling molecules, they have the potential to positively influence other pathways commonly believed to be part of migraine pathophysiology, namely: mitochondrial functioning, oxidative stress, cerebral excitability, inflammation and the gut microbiome. This review will describe the mechanisms by which the presence of KBs, D-BHB in particular, could influence those migraine pathophysiological mechanisms. To this end, common abnormalities in migraines are summarised with a particular focus on clinical data, including phenotypic, biochemical, genetic and therapeutic studies. Experimental animal data will be discussed to elaborate on the potential therapeutic mechanisms of elevated KBs in migraine pathophysiology, with a particular focus on the actions of D-BHB. In complex diseases such as migraines, a therapy that can target multiple possible pathogenic pathways seems advantageous. Further research is needed to establish whether the absence/restriction of dietary carbohydrates, the presence of KBs, or both, are of primary importance for the migraine protective effects of the KD.

Analyzing the Mechanisms Behind Macrolide Antibiotic-Induced Liver Injury Using Quantitative Systems Toxicology Modeling

PURPOSE

Macrolide antibiotics are commonly prescribed treatments for drug-resistant bacterial infections; however, many macrolides have been shown to cause liver enzyme elevations and one macrolide, telithromycin, has been pulled from the market by its provider due to liver toxicity. This work seeks to assess the mechanisms responsible for the toxicity of macrolide antibiotics.

METHODS

Five macrolides were assessed in in vitro systems designed to test for bile acid transporter inhibition, mitochondrial dysfunction, and oxidative stress. The macrolides were then represented in DILIsym, a quantitative systems pharmacology (QST) model of drug-induced liver injury, placing the in vitro results in context with each compound's predicted liver exposure and known biochemistry.

RESULTS

DILIsym results suggest that solithromycin and clarithromycin toxicity is primarily due to inhibition of the mitochondrial electron transport chain (ETC) while erythromycin toxicity is primarily due to bile acid transporter inhibition. Telithromycin and azithromycin toxicity was not predicted by DILIsym and may be caused by mechanisms not currently incorporated into DILIsym or by unknown metabolite effects.

CONCLUSIONS

The mechanisms responsible for toxicity can be significantly different within a class of drugs, despite the structural similarity among the drugs. QST modeling can provide valuable insight into the nature of these mechanistic differences.

Mitochondrial DNA copy number is associated with psychosis severity and anti-psychotic treatment

Mitochondrial pathology has been implicated in the pathogenesis of psychotic disorders. A few studies have proposed reduced leukocyte mitochondrial DNA (mtDNA) copy number in schizophrenia and bipolar disorder type I, compared to healthy controls. However, it is unknown if mtDNA copy number alteration is driven by psychosis, comorbidity or treatment. Whole blood mtDNA copy number was determined in 594 psychosis patients and corrected for platelet to leukocyte count ratio (mtDNAcn_res). The dependence of mtDNAcn_res on clinical profile, metabolic comorbidity and antipsychotic drug exposure was assessed. mtDNAcn_res was reduced with age (β = −0.210, p < 0.001), use of clozapine (β = −0.110,p = 0.012) and risperidone (β = −0.109,p = 0.014), dependent on prescribed dosage (p = 0.006 and p = 0.026, respectively), and the proportion of life on treatment (p = 0.006). Clozapine (p = 0.0005) and risperidone (p = 0.0126) had a reducing effect on the mtDNA copy number also in stem cell-derived human neurons in vitro at therapeutic plasma levels. For patients not on these drugs, psychosis severity had an effect (β = −0.129, p = 0.017), similar to age (β = −0.159, p = 0.003) and LDL (β = −0.119, p = 0.029) on whole blood mtDNAcn_res. Further research is required to determine if mtDNAcn_res reflects any psychosis-intrinsic mitochondrial changes.

Combination Effect of Silver Nanoparticles and Histone Deacetylases Inhibitor in Human Alveolar Basal Epithelial Cells

Although many treatment strategies have been reported for lung disease, the mechanism of combination therapy using silver nanoparticles (AgNPs) and histone deacetylases inhibitors (HDACi) remains unclear. Therefore, innovative treatment strategies are essential for addressing the therapeutic challenges of this highly aggressive lung cancer. AgNPs and HDACi seem to be the best candidates for anticancer therapy because of their anti-proliferative effect in a variety of cancer cells. First, we synthesized AgNPs using wogonin as a reducing and stabilizing agent, following which the synthesized AgNPs were characterized by various analytical techniques. The synthesized AgNPs exhibited dose- and size-dependent toxicity towards A549 cells. Interestingly, the combination of AgNPs and MS-275 significantly induces apoptosis, which was accompanied by an increased level of reactive oxygen species (ROS); leakage of lactate dehydrogenase (LDH); secretion of TNFα; dysfunction of mitochondria; accumulation autophagosomes; caspase 9/3 activation; up and down regulation of pro-apoptotic genes and anti-apoptotic genes, respectively; and eventually, induced DNA-fragmentation. Our findings suggest that AgNPs and MS-275 induce cell death in A549 lung cells via the mitochondrial-mediated intrinsic apoptotic pathway. Finally, our data show that the combination of AgNPs and MS-275 is a promising new approach for the treatment of lung cancer and our findings contribute to understanding the potential roles of AgNPs and MS-275 in pulmonary disease. However, further study is warranted to potentiate the use of this combination therapy in cancer therapy trials.

Modulation of host central carbon metabolism and in situ glucose uptake by intracellular Trypanosoma cruzi amastigotes

Obligate intracellular pathogens satisfy their nutrient requirements by coupling to host metabolic processes, often modulating these pathways to facilitate access to key metabolites. Such metabolic dependencies represent potential targets for pathogen control, but remain largely uncharacterized for the intracellular protozoan parasite and causative agent of Chagas disease, Trypanosoma cruzi. Perturbations in host central carbon and energy metabolism have been reported in mammalian T. cruzi infection, with no information regarding the impact of host metabolic changes on the intracellular amastigote life stage. Here, we performed cell-based studies to elucidate the interplay between infection with intracellular T. cruzi amastigotes and host cellular energy metabolism. T. cruzi infection of non-phagocytic cells was characterized by increased glucose uptake into infected cells and increased mitochondrial respiration and mitochondrial biogenesis. While intracellular amastigote growth was unaffected by decreased host respiratory capacity, restriction of extracellular glucose impaired amastigote proliferation and sensitized parasites to further growth inhibition by 2-deoxyglucose. These observations led us to consider whether intracellular T. cruzi amastigotes utilize glucose directly as a substrate to fuel metabolism. Consistent with this prediction, isolated T. cruzi amastigotes transport extracellular glucose with kinetics similar to trypomastigotes, with subsequent metabolism as demonstrated in ¹³C-glucose labeling and substrate utilization assays. Metabolic labeling of T. cruzi-infected cells further demonstrated the ability of intracellular parasites to access host hexose pools in situ. These findings are consistent with a model in which intracellular T. cruzi amastigotes capitalize on the host metabolic response to parasite infection, including the increase in glucose uptake, to fuel their own metabolism and replication in the host cytosol. Our findings enrich current views regarding available carbon sources for intracellular T. cruzi amastigotes and underscore the metabolic flexibility of this pathogen, a feature predicted to underlie successful colonization of tissues with distinct metabolic profiles in the mammalian host.

The kinetoplastid protozoan, Trypanosoma cruzi, is a highly successful parasite with a broad mammalian host range and the capacity to colonize a variety of tissues within a given host to establish life-long infection. T. cruzi infection causes Chagas disease in humans, characterized by severe cardiomyopathy and gastrointestinal motility disorders, with limited treatment options. Despite the critical role of T. cruzi amastigotes in sustaining mammalian infection, little is known about their metabolic requirements or the range of nutrients available to these parasites in the host cell cytoplasm. Here, we demonstrate that T. cruzi infection triggers a host response in infected cells that includes increased mitochondrial respiration and biogenesis and increased glucose uptake into infected cells. We show that exogenous glucose supports optimal intracellular parasite replication and that cytosolic T. cruzi amastigotes access glucose in situ, potentially via a facilitated transport process characterized here. These findings expand our view of the range of carbons available to the intracellular parasite and suggest even greater metabolic flexibility of the tissue-infective stages of T. cruzi than previously appreciated, a capability predicted to contribute to successful host colonization.

MitoepigenomeKB a comprehensive resource for human mitochondrial epigenetic data

Epigenetic modifications in the mitochondrial genome has been an emerging area of interest in the recent years in the field of mitochondrial biology. The renewed interest in the area has been largely fueled by a number of reports in the recent years suggesting the presence of epigenetic modifications in human mitochondrial genome and their associations with exposure to environmental factors and human diseases and or traits. Nevertheless there has been no systematic effort to curate, organize this information to enable cross-comparison between studies and datasets. We compiled 62 datasets from 9 studies on the epigenetic modifications in human mitochondrial genome to create a comprehensive catalog. This catalog is available as a user friendly interface - mitoepigenome^KB, where the data could be searched, browsed or visualized. The resource is available at URL: http://clingen.igib.res.in/mitoepigenome/. We hope mitoepigenome^KB would emerge as a central resource for datasets on epigenetic modifications in human mitochondria and would serve as the starting point to understanding the biology of human mitochondrial epigenome.

The pharmacogenomics of valproic acid

Valproic acid is an anticonvulsant and mood-stabilizing drug used primarily in the treatment of epilepsy and bipolar disorder. Adverse effects of valproic acid are rare, but hepatotoxicity is severe in particular in those younger than 2 years old and polytherapy. During valproic acid treatment, it is difficult for prescribers to predict its individual response. Recent advances in the field of pharmacogenomics have indicated variants of candidate genes that affect valproic acid efficacy and safety. In this review, a large number of candidate genes that influence valproic acid pharmacokinetics and pharmacodynamics are discussed, including metabolic enzymes, drug transporters, neurotransmitters and drug targets. Furthermore, pharmacogenomics is an important tool not only in further understanding of interindividual variability but also to assess the therapeutic potential of such variability in drug individualization and therapeutic optimization.

Inherited mitochondrial genomic instability and chemical exposures

There are approximately 1500 proteins that are needed for mitochondrial structure and function, most of which are encoded in the nuclear genome (Calvo et al., 2006). Each mitochondrion has its own genome (mtDNA), which in humans encodes 13 polypeptides, 22 tRNAs and 2 rRNAs required for oxidative phosphorylation. The mitochondrial genome of humans and most vertebrates is approximately 16.5kbp, double-stranded, circular, with few non-coding bases. Thus, maintaining mtDNA stability, that is, the ability of the cell to maintain adequate levels of mtDNA template for oxidative phosphorylation is essential and can be impacted by the level of mtDNA mutation currently within the cell or mitochondrion, but also from errors made during normal mtDNA replication, defects in mitochondrial quality control mechanisms, and exacerbated by exposures to exogenous and/or endogenous genotoxic agents. In this review, we expand on the origins and consequences of mtDNA instability, the current state of research regarding the mechanisms by which mtDNA instability can be overcome by cellular and chemical interventions, and the future of research and treatments for mtDNA instability.

Effects of antiepileptic drugs on mitochondrial functions, morphology, kinetics, biogenesis, and survival

OBJECTIVES

Antiepileptic drugs (AEDs) exhibit adverse and beneficial effects on mitochondria, which have a strong impact on the treatment of patients with a mitochondrial disorder (MID) with epilepsy (mitochondrial epilepsy). This review aims at summarizing and discussing recent findings concerning the effect of AEDs on mitochondrial functions and the clinical consequences with regard to therapy of mitochondrial epilepsy and of MIDs in general.

METHODS

Literature review.

RESULTS

AEDs may interfere with the respiratory chain, with non-respiratory chain enzymes, carrier proteins, or mitochondrial biogenesis, with carrier proteins, membrane-bound channels or receptors and the membrane potential, with anti-oxidative defense mechanisms, with morphology, dynamics and survival of mitochondria, and with the mtDNA. There are AEDs of which adverse effects outweigh beneficial effects, such as valproic acid, carbamazepine, phenytoin, or phenobarbital and there are AEDs in which beneficial effects dominate over mitochondrial toxic effects, such as lamotrigine, levetiracetam, gabapentin, or zonisamide. However, from most AEDs only little is known about their interference with mitochondria.

CONCLUSIONS

Mitochondrial epilepsy might be initially treated with AEDs with low mitochondrial toxic potential. Only in case mitochondrial epilepsy is refractory to these AEDs, AEDs with higher mitochondrial toxic potential might be tried. In patients carrying POLG1 mutations AEDs with high mitochondrial toxic potential are contraindicated.

Targeting hypoxic cancer stem cells (CSCs) with Doxycycline: Implications for optimizing anti-angiogenic therapy

Here, we report new mechanistic insight into how chronic hypoxia increases ‘stemness’ in cancer cells. Using chemical inhibitors, we provide direct experimental evidence that ROS production and mitochondrial biogenesis are both required for the hypoxia-induced propagation of CSCs. More specifically, we show that hypoxic CSCs can be effectively targeted with i) simple mitochondrial anti-oxidants (Mito-TEMPO) and/or ii) inhibitors of mitochondrial biogenesis (Doxycycline). In this context, we discuss the idea that mitochondrial biogenesis itself may be a primary driver of “stemness” in hypoxic cancer cells, with metabolic links to fatty acid oxidation (FAO). As Doxycycline is an FDA-approved drug, we propose that it could be re-purposed to target hypoxic CSCs, either alone or in combination with chemotherapy, i.e., Paclitaxel. For example, we demonstrate that Doxycycline effectively targets the sub-population of hypoxia-induced CSCs that are Paclitaxel-resistant, overcoming hypoxia-induced drug-resistance. Finally, anti-angiogenic therapy often induces tumor hypoxia, allowing CSCs to survive and propagate, ultimately driving tumor progression. Therefore, we suggest that Doxycycline could be used in combination with anti-angiogenic agents, to actively prevent or minimize hypoxia-induced treatment failure. In direct support of this assertion, Paclitaxel is already known to behave as an angiogenesis inhibitor.

Valproate Attenuates Nitroglycerin-Induced Trigeminovascular Activation by Preserving Mitochondrial Function in a Rat Model of Migraine

Background

Migraine is a chronic disease that interferes with life quality and work productivity. Valproate shows protective effects against migraine, yet the underlying mechanisms are unclear. This study aimed to evaluate the potential effect of valproate on migraine using a rat model of nitroglycerin-induced trigeminovascular activation, as well as to explore the underlying mechanism.

Material/Methods

Intraperitoneal injection of nitroglycerin was conducted to induce trigeminovascular activation in rats. To explore the protective effect of valproate, a low dose (100 mg/kg) or a high dose (200 mg/kg) of valproate was intraperitoneally injected into rats, and then the levels of 5-hydroxytryptamine and nitric oxide in the peripheral blood were examined. The mtDNA copy number and the protein levels of peroxisome proliferator-activated receptor-γ coactivator 1α, mitochondrial transcription factor A, and peroxisome proliferator-activated receptor-γ in the spinal trigeminal nucleus were detected to evaluate the biogenesis of mitochondria. The mitochondrial energy metabolism was determined by the mitochondrial membrane potential and the levels of adenosine triphosphate, cytochrome C oxidase, and reactive oxygen species.

Results

Valproate attenuated nitroglycerin-induced trigeminovascular activation in rats, with reduced scratching behavior and restored 5-hydroxytryptamine and nitric oxide levels. Moreover, the mitochondrial energy metabolism and the biogenesis of mitochondria were preserved by valproate in nitroglycerin-treated rats.

Conclusions

The protective effect of valproate against migraine may be achieved through the modulation of mitochondrial biogenesis and function. Our study provides evidence for the potential use of valproate in the treatment of migraine.

Toxicity of Antiepileptic Drugs to Mitochondria

Some of the side and beneficial effects of antiepileptic drugs (AEDs) are mediated via the influence on mitochondria. This is of particular importance in patients requiring AED treatment for mitochondrial epilepsy. AED treatment in patients with mitochondrial disorders should rely on the known influences of AEDs on these organelles. AEDs may influence various mitochondrial functions or structures in a beneficial or detrimental way. There are AEDs in which the toxic effect outweighs the beneficial effect, such as valproic acid (VPA), carbamazepine (CBZ), phenytoin (PHT), or phenobarbital (PB). There are, however, also AEDs in which the beneficial effect on mitochondria outweighs the mitochondrion-toxic effect, such as gabapentin (GBT), lamotrigine (LTG), levetiracetam (LEV), or zonisamide (ZNS). In the majority of the AEDs, however, information about their influence of mitochondria is lacking. In clinical practice mitochondrial epilepsy should be initially treated with AEDs with low mitochondrion-toxic potential. Only in cases of ineffectivity or severe mitochondrial epilepsy, mitochondrion-toxic AEDs should be given. This applies for AEDs given orally or intravenously.

Mitoepigenetics: The different shades of grey

Epigenetic modifications of the nuclear genome have been well studied and it is established that these modifications play a key role in nuclear gene expression. However, the status of mitochondrial epigenetic modifications has not been delved in detail. The recent technological advancements in the genome analyzing tools and techniques, have helped in investigating mitochondrial epigenetic modifications with greater resolution and studies have indicated a regulatory role of the mitochondrial epigenome. Association of mitochondrial DNA methylation with various disease conditions, drug treatment, aging, exposure to environmental pollutants etc. has lent credence to this belief. Herein, we have reviewed studies on mitochondrial epigenetic modifications with a focus to comprehend its regulatory role in gene expression and disease association.

A composite peripheral blood gene expression measure as a potential diagnostic biomarker in bipolar disorder

Gene expression in peripheral blood has the potential to inform on pathophysiological mechanisms and has emerged as a viable avenue for the identification of biomarkers. Here, we aimed to identify gene expression candidate genes and to explore the potential for a composite gene expression measure as a diagnostic and state biomarker in bipolar disorder. First, messenger RNA levels of 19 candidate genes were assessed in peripheral blood mononuclear cells of 37 rapid cycling bipolar disorder patients in different affective states (depression, mania and euthymia) during a 6-12-month period and in 40 age- and gender-matched healthy control subjects. Second, a composite gene expression measure was constructed in the first half study sample and independently validated in the second half of the sample. We found downregulation of POLG and OGG1 expression in bipolar disorder patients compared with healthy control subjects. In patients with bipolar disorder, upregulation of NDUFV2 was observed in a depressed state compared with a euthymic state. The composite gene expression measure for discrimination between patients and healthy control subjects on the basis of 19 genes generated an area under the receiver-operating characteristic curve of 0.81 (P < 0.0001) in sample 1, which was replicated with a value of 0.73 (P < 0.0001) in sample 2, corresponding with a moderately accurate test. The present findings of altered POLG, OGG1 and NDUFV2 expression point to disturbances within mitochondrial function and DNA repair mechanisms in bipolar disorder. Further, a composite gene expression measure could hold promise as a potential diagnostic biomarker.

Sodium valproate induces mitochondrial respiration dysfunction in HepG2 in vitro cell model

Sodium valproate (VPA) is a potentially hepatotoxic antiepileptic drug. Risk of VPA-induced hepatotoxicity is increased in patients with mitochondrial diseases and especially in patients with POLG1 gene mutations. We used a HepG2 cell in vitro model to investigate the effect of VPA on mitochondrial activity. Cells were incubated in glucose medium and mitochondrial respiration-inducing medium supplemented with galactose and pyruvate. VPA treatments were carried out at concentrations of 0-2.0mM for 24-72 h. In both media, VPA caused decrease in oxygen consumption rates and mitochondrial membrane potential. VPA exposure led to depleted ATP levels in HepG2 cells incubated in galactose medium suggesting dysfunction in mitochondrial ATP production. In addition, VPA exposure for 72 h increased levels of mitochondrial reactive oxygen species (ROS), but adversely decreased protein levels of mitochondrial superoxide dismutase SOD2, suggesting oxidative stress caused by impaired elimination of mitochondrial ROS and a novel pathomechanism related to VPA toxicity. Increased cell death and decrease in cell number was detected under both metabolic conditions. However, immunoblotting did not show any changes in the protein levels of the catalytic subunit A of mitochondrial DNA polymerase γ, the mitochondrial respiratory chain complexes I, II and IV, ATP synthase, E3 subunit dihydrolipoyl dehydrogenase of pyruvate dehydrogenase, 2-oxoglutarate dehydrogenase and glutathione peroxidase. Our results show that VPA inhibits mitochondrial respiration and leads to mitochondrial dysfunction, oxidative stress and increased cell death, thus suggesting an essential role of mitochondria in VPA-induced hepatotoxicity.

Retinal mitochondrial DNA mismatch repair in the development of diabetic retinopathy, and its continued progression after termination of hyperglycemia

PURPOSE

Mitochondrial DNA (mtDNA) is damaged in the retina in diabetes, and mitochondria copy numbers are decreased. The displacement-loop (D-loop) of the mtDNA, the region with transcription/replication elements, experiences more damage than other regions of mtDNA. Our aim was to examine the role of DNA mismatch repair (MMR) in mitochondria homeostasis in diabetic retinopathy, and in its continued progression after cessation of hyperglycemia.

METHODS

Effect of hyperglycemia on sequence variants in the D-loop region was investigated in retinal endothelial cells and in the retina from streptozotocin-induced diabetic rats using mismatch-specific surveyor nuclease. The role of MMR machinery in mtDNA damage and mitochondrial respiration was investigated in retinal endothelial cells overexpressing Mlh1, an MMR enzyme mainly associated with mtDNA polymerase gamma, or Msh2 (associated with nuclear polymerase beta).

RESULTS

Hyperglycemia increased sequence variants in the D-loop region. While overexpression of Mlh1 in endothelial cells ameliorated glucose-induced increase in D-loop sequence variants, decrease in respiration rate and increase in apoptosis, overexpression of Msh2 did not protect the mitochondria damage. Termination of hyperglycemia failed to reverse decrease in MMR enzymes and increase in D-loop sequence variants.

CONCLUSIONS

Due to a compromised MMR system, the sequence variants in the D-loop region were not repaired, and that resulted in impaired mtDNA transcription. Mitochondria become dysfunctional, and they continued to be dysfunctional even after hyperglycemia was terminated, contributing to the development, and progression of diabetic retinopathy. Thus, strategies targeting mitochondrial MMR machinery could help maintain mitochondria homeostasis, and inhibit the development of diabetic retinopathy and its continued progression.