Study of oxidative, enzymatic mitochondrial respiratory chain function and apoptosis in perinatally HIV-infected pediatric patients

Assessment of mitochondrial toxicity in newborns and infants with congenital cytomegalovirus infection treated with valganciclovir

BACKGROUND

Ganciclovir/valganciclovir is currently indicated during the first 6 months of life in symptomatic children with congenital cytomegalovirus (CMV) infection. However, this treatment may have the potential to induce mitochondrial toxicity due to off-target inhibition of DNA-polymerases. Similar anti-HIV drugs have been associated with mitochondrial toxicity but this has never been explored in CMV.

OBJECTIVE

To determine the potential mitochondrial toxicity profile at the genetic, functional and biogenesis level in peripheral blood mononuclear cells from a cohort of newborns and infants with symptomatic congenital CMV infection (treated with valganciclovir, untreated and uninfected controls).

DESIGN

Longitudinal, observational and controlled study.

SETTING AND PATIENTS

Subjects were recruited at the tertiary referral Hospital Sant Joan de Déu and experiments were conducted at IDIBAPS-Hospital Clínic of Barcelona, Spain. CMV-infected newborns underwent comprehensive monthly clinical follow-up.

METHODS

Mitochondrial parameters, audiometry and neurological assessment were measured at baseline, 3-6 and 12 months after inclusion in the study. The Kruskal-Wallis test for k-independent samples and Friedman tests for repeated measurements were applied.

RESULTS

Complex IV, citrate synthase enzymatic activities and mtDNA remained preserved in congenital CMV-infected infants treated with valganciclovir compared with controls (p>0.05 in all cases).

CONCLUSIONS

No evidence of mitochondrial toxicity was found in infants treated with valganciclovir for congenital CMV.

Mitochondrial and autophagic alterations in skin fibroblasts from Parkinson disease patients with Parkin mutations

PRKN encodes an E3-ubiquitin-ligase involved in multiple cell processes including mitochondrial homeostasis and autophagy. Previous studies reported alterations of mitochondrial function in fibroblasts from patients with PRKN mutation-associated Parkinson’s disease (PRKN-PD) but have been only conducted in glycolytic conditions, potentially masking mitochondrial alterations. Additionally, autophagy flux studies in this cell model are missing.

We analyzed mitochondrial function and autophagy in PRKN-PD skin-fibroblasts (n=7) and controls (n=13) in standard (glucose) and mitochondrial-challenging (galactose) conditions.

In glucose, PRKN-PD fibroblasts showed preserved mitochondrial bioenergetics with trends to abnormally enhanced mitochondrial respiration that, accompanied by decreased CI, may account for the increased oxidative stress. In galactose, PRKN-PD fibroblasts exhibited decreased basal/maximal respiration vs. controls and reduced mitochondrial CIV and oxidative stress compared to glucose, suggesting an inefficient mitochondrial oxidative capacity to meet an extra metabolic requirement. PRKN-PD fibroblasts presented decreased autophagic flux with reduction of autophagy substrate and autophagosome synthesis in both conditions.

The alterations exhibited under neuron-like oxidative environment (galactose), may be relevant to the disease pathogenesis potentially explaining the increased susceptibility of dopaminergic neurons to undergo degeneration. Abnormal PRKN-PD phenotype supports the usefulness of fibroblasts to model disease and the view of PD as a systemic disease where molecular alterations are present in peripheral tissues.

Mitochondrial Impairment in Well-Suppressed Children with Perinatal HIV-Infection on Antiretroviral Therapy

Mitochondrial impairment is reported in HIV-infected children receiving antiretroviral therapy (ART), as well as those naive to ART. Whether mitochondrial function recovers with early initiation of ART and sustained viral suppression on long-term ART is unclear. In this study, we evaluate mitochondrial markers in well-suppressed perinatally HIV-infected children initiated on ART early in life. We selected a cross-sectional sample of 120 HIV-infected children with viral load <400 copies/mL and 60 age-matched uninfected children (22 HIV-exposed uninfected) enrolled in a cohort study in Johannesburg, South Africa. Complex IV (CIV) and citrate synthase (CS) activity were measured by spectrophotometry. Mitochondrial DNA (mtDNA) content relative to nuclear DNA (nDNA) was measured by quantitative real-time polymerase chain reaction and expressed as copies/nDNA. Mitochondrial markers were impaired in HIV-infected children, including lower mean CIV activities [1.76 vs. 1.40 optical densities (OD)/min], higher risk of a CIV/CS ratio ≤0.22 (third quartile; odds ratio = 3.03, 95% confidence interval: 1.38-6.66), and lower mtDNA content. Children with shorter versus longer ART duration (<6.3 vs. ≥6.3 years) had lower means of CIV activity (1.22-1.58 OD/min) and mtDNA content (386-907 copies/nDNA). There were no differences in mitochondrial markers between children who started ART earlier (<6 months) or later (6-24 months). CIV activity was impaired in children with lower height-for-age Z-scores (HAZs). Despite early treatment and prolonged viral suppression, HIV-infected children had detectable mitochondrial impairment, particularly among those with stunted growth. Further study is required to determine if continued treatment will lead to full recovery of mitochondrial function in HIV-infected children.

Hemagglutinin-neuraminidase and fusion proteins of virulent Newcastle disease virus cooperatively disturb fusion-fission homeostasis to enhance mitochondrial function by activating the unfolded protein response of endoplasmic reticulum and mitochondrial stress

The fusogenically activated F and HN proteins of virulent NDV induce complete autophagic flux in DF-1 and A549 cells. However, the effect of both glycoproteins on mitochondria remains elusive. Here, we found that F and HN cooperation increases mitochondrial biogenesis but does not cause the mitochondria damage. We observed that both glycoproteins change the morphological characteristics and spatial distribution of intracellular mitochondria. F and HN cooperate cooperatively to induce ER stress and UPR^mt. Our preliminary data suggested that F and HN cooperatively disturb mitochondrial fusion–fission homeostasis to enhance mitochondrial biogenesis, and eventually meet the energy demand of syncytium formation.

Exhaustion of mitochondrial and autophagic reserve may contribute to the development of LRRK2 G2019S -Parkinson's disease

Background

Mutations in leucine rich repeat kinase 2 (LRRK2) are the most common cause of familial Parkinson’s disease (PD). Mitochondrial and autophagic dysfunction has been described as etiologic factors in different experimental models of PD. We aimed to study the role of mitochondria and autophagy in LRRK2^G2019S-mutation, and its relationship with the presence of PD-symptoms.

Methods

Fibroblasts from six non-manifesting LRRK2^G2019S-carriers (NM-LRRK2^G2019S) and seven patients with LRRK2^G2019S-associated PD (PD-LRRK2^G2019S) were compared to eight healthy controls (C). An exhaustive assessment of mitochondrial performance and autophagy was performed after 24-h exposure to standard (glucose) or mitochondrial-challenging environment (galactose), where mitochondrial and autophagy impairment may be heightened.

Results

A similar mitochondrial phenotype of NM-LRRK2^G2019S and controls, except for an early mitochondrial depolarization (54.14% increased, p = 0.04), was shown in glucose. In response to galactose, mitochondrial dynamics of NM-LRRK2^G2019S improved (− 17.54% circularity, p = 0.002 and + 42.53% form factor, p = 0.051), probably to maintain ATP levels over controls. A compromised bioenergetic function was suggested in PD-LRRK2^G2019S when compared to controls in glucose media. An inefficient response to galactose and worsened mitochondrial dynamics (− 37.7% mitochondrial elongation, p = 0.053) was shown, leading to increased oxidative stress. Autophagy initiation (SQTSM/P62) was upregulated in NM-LRRK2^G2019S when compared to controls (glucose + 118.4%, p = 0.014; galactose + 114.44%, p = 0.009,) and autophagosome formation increased in glucose media. Despite of elevated SQSTM1/P62 levels of PD-NM^G2019S when compared to controls (glucose + 226.14%, p = 0.04; galactose + 78.5%, p = 0.02), autophagosome formation was deficient in PD-LRRK2^G2019S when compared to NM-LRRK2^G2019S (− 71.26%, p = 0.022).

Conclusions

Enhanced mitochondrial performance of NM-LRRK2^G2019S in mitochondrial-challenging conditions and upregulation of autophagy suggests that an exhaustion of mitochondrial bioenergetic and autophagic reserve, may contribute to the development of PD in LRRK2^G2019S mutation carriers.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1526-3) contains supplementary material, which is available to authorized users.

Placental Mitochondrial Toxicity, Oxidative Stress, Apoptosis, and Adverse Perinatal Outcomes in HIV Pregnancies Under Antiretroviral Treatment Containing Zidovudine

OBJECTIVE

To determine whether mitochondrial, oxidative, and apoptotic abnormalities in placenta derived from HIV and combined antiretroviral therapy (cART) containing zidovudine (AZT) could be associated with adverse perinatal outcome.

DESIGN

Cross-sectional, controlled, observational study.

METHODS

We studied obstetric results and mitochondrial, oxidative, and apoptotic state in placenta of 24 treated HIV-infected and 32 -uninfected pregnant women. We measured mitochondrial DNA (mtDNA) content by quantitative reverse transcriptase-polymerase chain reaction (mtND2/n18SrRNA), oxidative stress by the spectrophotometric quantification of lipid peroxidation and apoptosis by Western blot analysis of active caspase-3 respect to β-actin content and analysis of the terminal deoxynucleotidyl transferase dUTP nick end labeling.

RESULTS

Global adverse perinatal outcome (defined as preterm delivery or/and small newborns for gestational age) was significantly increased in HIV pregnancies [or 6.7 (1.3-33.2); P < 0.05]. mtDNA content in HIV-infected women was significantly depleted (39.20% ± 2.78%) with respect to controls (0.59 ± 0.03 vs. 0.97 ± 0.07; P < 0.001). A significant 29.50% ± 9.14% increase in oxidative stress was found in placentas of HIV-infected women (23.23 ± 1.64 vs. 17.94 ± 1.03; P < 0.01). A trend toward 41.18% ± 29.41% increased apoptosis active caspase-3/β-actin was found in HIV patients (0.48 ± 0.10 vs. 0.34 ± 0.05; P = not significant), confirmed by transferase dUTP nick end labeling assay. Adverse perinatal outcome did not correlate mitochondrial, oxidative, or apoptotic findings.

CONCLUSIONS

Placentas of HIV-infected pregnant women under AZT cART showed evidence of mtDNA depletion, increased oxidative stress levels, and apoptosis suggestive of secondary mitochondrial failure, potential base of associated adverse perinatal outcome. Despite the fact that further demonstration of causality would need new approaches and bigger sample sizes, AZT-sparing cART should be considered in the context of pregnancy.

Distinct Mitochondrial Disturbance in CD4+T and CD8+T Cells From HIV-Infected Patients

BACKGROUND

Mitochondrial dysfunction has frequently been found in HIV-infected patients regardless of whether they received antiretroviral therapy (ART). Accumulating evidence suggests that HIV-infected patients exhibit marked changes in mitochondrial membrane potential (MMP), reactive oxygen species (ROS) accumulation, adenosine triphosphate generation, mitochondrial mass (MM), mitochondrial DNA, etc. However, mitochondrial toxicity in CD4T and CD8T cells caused by different levels of HIV progression and ART is poorly understood.

METHODS

Blood samples were obtained from 97 ART-naïve HIV-infected patients with different CD4T cell counts, 97 nucleoside-reverse transcriptase inhibitors-exposed HIV-infected patients, and 25 HIV-negative subjects. MMP, ROS, and MM in CD4T and CD8T cells were assessed by flow cytometry.

RESULTS

In healthy subjects, the levels of MMP and MM in CD4T cells were higher than those in CD8T cells. HIV infection led to an increase in MM in CD4T and CD8T cells, but mainly influenced MMP in CD8T cells and ROS accumulation in CD4T cells. MM in CD4T and CD8T cells gradually increased after the loss of CD4T cells. Although the dynamic changes in MMP in CD4T cells were different from those in CD8T cells during highly active ART, MM in both CD4T and CD8T cells was significantly decreased after 2 years of therapy, but increased again after 3 years.

CONCLUSIONS

HIV infection and antiretroviral therapy both led to mitochondrial disturbances in CD4T cells and CD8T cells; however, the abnormal changes in mitochondrial parameters in CD4+T cells were different from those in CD8T cells caused by HIV infection and antiretroviral therapy.

Impaired Mitochondrial Function and Dynamics in the Pathogenesis of FXTAS

Mitochondrial involvement plays an important role in neurodegenerative diseases. At least one-third of adult carriers of a FMR1 premutation (55-200 CGG repeats) are at risk of presenting an adult-onset neurodegenerative disorder known as fragile X-associated tremor/ataxia syndrome (FXTAS). In an attempt to provide new insights into the mechanisms involved in the pathogenesis of FXTAS, we characterized mitochondrial function and dynamics by the assessment of oxidative respiratory chain function, mitochondrial content, oxidative stress levels, and mitochondrial network complexity. Regarding mitochondrial function, we found that mitochondrial respiratory capacity is compromised in skin fibroblasts whereas in blood, no differences were observed between the FXTAS and control groups. Furthermore, fibroblasts from FXTAS patients presented altered mitochondrial architecture, with more circular and less interconnected mitochondria being observed. Mitochondrial function and dynamics deregulation and characteristic of neurological disorders are present in FXTAS patients. These features might be limiting temporal and spatial bioenergetics cells supply and thus contributing to disease pathogenesis.

Mitochondrial toxicity and caspase activation in HIV pregnant women

To assess the impact of HIV-infection and highly active anti-retroviral treatment in mitochondria and apoptotic activation of caspases during pregnancy and their association with adverse perinatal outcome. Changes of mitochondrial parameters and apoptotic caspase activation in maternal peripheral blood mononuclear cells were compared at first trimester of pregnancy and delivery in 27 HIV-infected and -treated pregnant women versus 24 uninfected pregnant controls. We correlated immunovirological, therapeutic and perinatal outcome with experimental findings: mitochondrial DNA (mtDNA) content, mitochondrial protein synthesis, mitochondrial function and apoptotic caspase activation. The HIV pregnancies showed increased adverse perinatal outcome (OR: 4.81 [1.14-20.16]; P < 0.05) and decreased mtDNA content (42.66 ± 5.94%, P < 0.01) compared to controls, even higher in naïve participants. This depletion caused a correlated decrease in mitochondrial protein synthesis (12.82 ± 5.73%, P < 0.01) and function (20.50 ± 10.14%, P < 0.001), not observed in controls. Along pregnancy, apoptotic caspase-3 activation increased 63.64 ± 45.45% in controls (P < 0.001) and 100.00 ± 47.37% in HIV-pregnancies (P < 0.001), in correlation with longer exposure to nucleoside analogues. HIV-infected women showed increased obstetric problems and declined genetic and functional mitochondrial parameters during pregnancy, especially those firstly exposed to anti-retrovirals. The apoptotic activation of caspases along pregnancy is emphasized in HIV pregnancies promoted by nucleoside analogues. However, we could not demonstrate direct mitochondrial or apoptotic implication in adverse obstetric outcome probably because of the reduced sample size.

Mitochondrial DNA disturbances and deregulated expression of oxidative phosphorylation and mitochondrial fusion proteins in sporadic inclusion body myositis

Sporadic inclusion body myositis (sIBM) is one of the most common myopathies in elderly people. Mitochondrial abnormalities at the histological level are present in these patients. We hypothesize that mitochondrial dysfunction may play a role in disease aetiology. We took the following measurements of muscle and peripheral blood mononuclear cells (PBMCs) from 30 sIBM patients and 38 age- and gender-paired controls: mitochondrial DNA (mtDNA) deletions, amount of mtDNA and mtRNA, mitochondrial protein synthesis, mitochondrial respiratory chain (MRC) complex I and IV enzymatic activity, mitochondrial mass, oxidative stress and mitochondrial dynamics (mitofusin 2 and optic atrophy 1 levels). Depletion of mtDNA was present in muscle from sIBM patients and PBMCs showed deregulated expression of mitochondrial proteins in oxidative phosphorylation. MRC complex IV/citrate synthase activity was significantly decreased in both tissues and mitochondrial dynamics were affected in muscle. Depletion of mtDNA was significantly more severe in patients with mtDNA deletions, which also presented deregulation of mitochondrial fusion proteins. Imbalance in mitochondrial dynamics in muscle was associated with increased mitochondrial genetic disturbances (both depletion and deletions), demonstrating that proper mitochondrial turnover is essential for mitochondrial homoeostasis and muscle function in these patients.

The global burden of oral diseases in pediatric HIV-infected populations: a workshop report

OBJECTIVES

To achieve a comprehensive understanding about the global burden of oral diseases in HIV-infected children and to identify research needs.

MATERIALS AND METHODS

A literature search was conducted in PubMed (2009-2014) to address five questions: (i) prevalence of oral diseases in HIV-infected compared with uninfected children, (ii) impact of oral diseases on quality of life, (iii) effect of antiretroviral exposure in utero on craniofacial and dental development, (iv) important co-infections and antiretroviral complications, and (v) value of atraumatic restorative treatment.

RESULTS

Studies showed a high prevalence of dental caries in HIV-infected children but the relationship between HIV infection and dental caries remains unclear. Also quality of life needs further investigation supported by better study designs and improvement of the instruments used. Up-to-date evidence suggested long-term harms associated with in utero antiretroviral exposure were minor but would require long-term follow-up through National Registries. The reviews also revealed the wide spectrum of metabolic disease due to antiretroviral therapy and co-infections such as tuberculosis. Finally, atraumatic restorative technique appears to be a simple and safe technique to treat dental caries but outcomes need further evaluation.

CONCLUSIONS

The impact of antiretroviral therapy in HIV-infected children has raised novel challenging questions in the field of oral health warranting future research.

Mitochondrial and apoptotic in vitro modelling of differential HIV-1 progression and antiretroviral toxicity

OBJECTIVES

Ex vivo analysis of mitochondrial function may reveal HIV progression and the impact of ART. We propose a mitochondrial and apoptotic in vitro model using Jurkat T cells incubated with plasma. The objectives of this study were to evaluate mitochondrial and apoptotic lesions in this model in relation to HIV progression, and to assess the effect of >1 year of standard non-thymidine-containing therapy.

METHODS

This was a cross-sectional comparison among three age- and gender-matched groups (n = 19 × 3): healthy non-HIV-infected participants, HIV-infected long-term non-progressors (LTNPs) and standard antiretroviral-naive chronically infected patients [standard progressors (Sps)], longitudinally evaluated before (Sp1) and after (Sp2) >1 year of efavirenz + tenofovir + emtricitabine therapy. We analysed mitochondrial DNA content by RT-PCR, mitochondrial function by spectrophotometry, mitochondrial protein synthesis by western blot analysis, mitochondrial dynamics by western blot analysis (MFN2), apoptotic transition pore formation by western blot analysis (VDAC-1) and mitochondrial membrane potential and annexin V/propidium iodide fluorescence by flow cytometry.

RESULTS

There was a decreasing non-significant trend towards lower mitochondrial parameters for HIV-infected values with respect to uninfected control reference values. HIV progression (LTNP versus Sp1) was associated with decreased mitochondrial genetic, functional and translational parameters, which partially recovered after treatment intervention (Sp2). Mitochondrial fusion showed a trend to decrease non-significantly in Sp patients compared with LTNP patients, especially after therapy. All apoptotic parameters showed a trend to increase in Sp1 with respect to LTNP, followed by recovery in Sp2.

CONCLUSIONS

We proposed an in vitro model for mitochondrial and apoptotic assessment to test the effects of HIV infection and its therapy, resembling in vivo conditions. This model could be useful for clinical research purposes.

A renewed focus on the interplay between viruses and mitochondrial metabolism

Mitochondria fulfil several key functions within cellular metabolic and antiviral signalling pathways, including their central role in ATP generation. Viruses, as intracellular parasites, require from their cellular host the building blocks for generation of their viral progeny and the energy that drives viral replication and assembly. While some viruses have adopted ways to manipulate the infected cell such that cellular metabolism supports optimal virus production, other viruses simply exhaust cellular resources. The association of viruses with mitochondria is influenced by several important factors such as speed of the viral replication cycle and viral dependence on cellular enzymes and metabolites. This review will highlight the complex interconnectivity of viral life cycles with the three main mitochondrial metabolic pathways, namely β-oxidation, the tricarboxylic (TCA) cycle, and oxidative phosphorylation. This interconnectivity has the potential to reveal interesting points for antiviral therapy with either prometabolites or antimetabolites and highlights the importance of the viral association with mitochondrial metabolism.