Activities of respiratory chain complexes in isolated platelets in females with anorexia nervosa

Mitochondrial impairment, decreased sirtuin activity and protein acetylation in dorsal root ganglia in Friedreich Ataxia models

Friedreich ataxia (FA) is a rare, recessive neuro-cardiodegenerative disease caused by deficiency of the mitochondrial protein frataxin. Mitochondrial dysfunction, a reduction in the activity of iron-sulfur enzymes, iron accumulation, and increased oxidative stress have been described. Dorsal root ganglion (DRG) sensory neurons are among the cellular types most affected in the early stages of this disease. However, its effect on mitochondrial function remains to be elucidated. In the present study, we found that in primary cultures of DRG neurons as well as in DRGs from the FXNI151F mouse model, frataxin deficiency resulted in lower activity and levels of the electron transport complexes, mainly complexes I and II. In addition, altered mitochondrial morphology, indicative of degeneration was observed in DRGs from FXNI151F mice. Moreover, the NAD+/NADH ratio was reduced and sirtuin activity was impaired. We identified alpha tubulin as the major acetylated protein from DRG homogenates whose levels were increased in FXNI151F mice compared to WT mice. In the mitochondria, superoxide dismutase (SOD2), a SirT3 substrate, displayed increased acetylation in frataxin-deficient DRG neurons. Since SOD2 acetylation inactivates the enzyme, and higher levels of mitochondrial superoxide anion were detected, oxidative stress markers were analyzed. Elevated levels of hydroxynonenal bound to proteins and mitochondrial Fe2+ accumulation was detected when frataxin decreased. Honokiol, a SirT3 activator, restores mitochondrial respiration, decreases SOD2 acetylation and reduces mitochondrial superoxide levels. Altogether, these results provide data at the molecular level of the consequences of electron transport chain dysfunction, which starts negative feedback, contributing to neuron lethality. This is especially important in sensory neurons which have greater susceptibility to frataxin deficiency compared to other tissues.

Brain Volume Loss, Astrocyte Reduction, and Inflammation in Anorexia Nervosa

Anorexia nervosa is the third most common chronic disease in adolescence and is characterized by low body weight, body image distortion, weight phobia, and severe somatic consequences. Among the latter, marked brain volume reduction has been linked to astrocyte cell count reduction of about 50% in gray and white matter, while neuronal and other glial cell counts remain normal. Exact underlying mechanisms remain elusive; however, first results point to important roles of the catabolic state and the very low gonadal steroid hormones in these patients. They also appear to involve inflammatory states of "hungry astrocytes" and interactions with the gut microbiota. Functional impairments could affect the role of astrocytes in supporting neurons metabolically, neurotransmitter reuptake, and synapse formation, among others. These could be implicated in reduced learning, mood alterations, and sleep disturbances often seen in patients with AN and help explain their rigidity and difficulties in relearning processes in psychotherapy during starvation.

Mitochondrial Dysfunction in Blood Platelets of Patients with Manic Episode of Bipolar Disorder

OBJECTIVES

The bipolar affective disorder (BAD) pathophysiology is multifactorial and has not been fully clarified.

METHOD

We measured selected mitochondrial parameters in peripheral blood components. The analyses were performed for patients suffering from a manic episode during remission and were compared to those performed for healthy controls. BAD was clinically evaluated using well-established diagnostic scales and questionnaires. Mitochondrial respiration was examined in intact and permeabilized blood platelets using high-resolution respirometry. The citrate synthase (CS) and electron transport system (ETS) complex (complex I, II, and IV) activities were examined in platelets.

RESULTS

The CS, complex II and complex IV activities were decreased in the BAD patients, complex I activity was increased, and the ratio of complex I to CS was significantly increased. In the intact platelets, respiration after complex I inhibition and residual oxygen consumption were decreased in the BAD patients compared to the healthy controls. In the permeabilized platelets, a decreased ETS capacity was found in the BAD patients. No significant differences were found between BAD patients in mania and remission.

CONCLUSION

Increased complex I activity can be a compensatory mechanism for decreased CS and complex II and IV activities. We conclude that complex I and its abnormal activity contribute to defects in cellular energy metabolism during a manic episode and that the deficiency in the complex's functioning, but not the availability of oxidative phosphorylation substrates, seems to be responsible for the decreased ETS capacity in BAD patients. The observed parameters can be further evaluated as 'trait' markers of BAD.

Anorexia Nervosa and the Immune System-A Narrative Review

The pathogenesis of an increasing number of chronic diseases is being attributed to effects of the immune system. However, its role in the development and maintenance of anorexia nervosa is seemingly under-appreciated. Yet, in examining the available research on the immune system and genetic studies in anorexia nervosa, one becomes increasingly suspicious of the immune system’s potential role in the pathophysiology of anorexia nervosa. Specifically, research is suggestive of increased levels of various pro-inflammatory cytokines as well as the spontaneous production of tumor necrosis factor in anorexia nervosa; genetic studies further support a dysregulated immune system in this disorder. Potential contributors to this dysregulated immune system are discussed including increased oxidative stress, chronic physiological/psychological stress, changes in the intestinal microbiota, and an abnormal bone marrow microenvironment, all of which are present in anorexia nervosa.

The relationship of mitochondrial dysfunction and the development of insulin resistance in Cushing's syndrome

PURPOSE

Cushing's syndrome is characterized by metabolic disturbances including insulin resistance. Mitochondrial dysfunction is one pathogenic factor in the development of insulin resistance in patients with obesity. We explored whether mitochondrial dysfunction correlates with insulin resistance and other metabolic complications.

PATIENTS AND METHODS

We investigated the changes of mRNA expression of genes encoding selected subunits of oxidative phosphorylation system (OXPHOS), pyruvate dehydrogenase (PDH) and citrate synthase (CS) in subcutaneous adipose tissue (SCAT) and peripheral monocytes (PM) and mitochondrial enzyme activity in platelets of 24 patients with active Cushing's syndrome and in 9 of them after successful treatment and 22 healthy control subjects.

RESULTS

Patients with active Cushing's syndrome had significantly increased body mass index (BMI), homeostasis model assessment of insulin resistance (HOMA-IR) and serum lipids relative to the control group. The expression of all investigated genes for selected mitochondrial proteins was decreased in SCAT in patients with active Cushing's syndrome and remained decreased after successful treatment. The expression of most tested genes in SCAT correlated inversely with BMI and HOMA-IR. The expression of genes encoding selected OXPHOS subunits and CS was increased in PM in patients with active Cushing's syndrome with a tendency to decrease toward normal levels after cure. Patients with active Cushing's syndrome showed increased enzyme activity of complex I (NQR) in platelets.

CONCLUSION

Mitochondrial function in SCAT in patients with Cushing's syndrome is impaired and only slightly affected by its treatment which may reflect ongoing metabolic disturbances even after successful treatment of Cushing's syndrome.

Disturbances of mitochondrial parameters to distinguish patients with depressive episode of bipolar disorder and major depressive disorder

BACKGROUND

Mitochondrial dysfunctions are implicated in the pathophysiology of mood disorders. We measured and examined the following selected mitochondrial parameters: citrate synthase (CS) activity, electron transport system (ETS) complex (complexes I, II, and IV) activities, and mitochondrial respiration in blood platelets.

PATIENTS AND METHODS

The analyses were performed for 24 patients suffering from a depressive episode of bipolar affective disorder (BD), compared to 68 patients with MDD and 104 healthy controls. BD and unipolar depression were clinically evaluated using well-established diagnostic scales and questionnaires.

RESULTS

The CS, complex II, and complex IV activities were decreased in the depressive episode of BD patients; complex I and complex I/CS ratio were significantly increased compared to healthy controls. We observed significantly decreased complex II and CS activities in patients suffering from MDD compared to controls. Decreased respiration after complex I inhibition and increased residual respiration were found in depressive BD patients compared to controls. Physiological respiration and capacity of the ETS were decreased, and respiration after complex I inhibition was increased in MDD patients, compared to controls. Increased complex I activity can be a compensatory mechanism for decreased CS and complex II and IV activities.

CONCLUSION

We can conclude that complex I and its abnormal activity contribute to the defects in cellular energy metabolism during a depressive episode of BD. The observed parameters could be used in a panel of biomarkers that could selectively distinguish BD depression from MDD and can be easily examined from blood elements.

Buccal Respiratory Chain Complexes I and IV Quantities in Huntington's Disease Patients

Alterations in mitochondrial parameters are an important hallmark of Huntington's disease (HD). The ubiquitous expression of mutant huntingtin raises the prospect that mitochondrial disturbances can also be detected and monitored through buccal epithelial cells. In a group of 34 patients with Huntington's disease and a group of 22 age-related healthy volunteers, respiratory complex I and IV protein quantities in buccal epithelial cells were measured using the dipstick immunocapture assay. The protein quantity of respiratory complex I correlates with age (r = 0.427, P = 0.026, FWE-P = 0.156) in the patient group, but not in the group of healthy subjects. Our non-invasive approach allows us to obtain valuable information for the studies of mitochondrial biochemical parameters in patients with neurodegenerative diseases and could also be useful in epidemiological studies.

Statin-induced changes in mitochondrial respiration in blood platelets in rats and human with dyslipidemia

3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) are widely used drugs for lowering blood lipid levels and preventing cardiovascular diseases. However, statins can have serious adverse effects, which may be related to development of mitochondrial dysfunctions. The aim of study was to demonstrate the in vivo effect of high and therapeutic doses of statins on mitochondrial respiration in blood platelets. Model approach was used in the study. Simvastatin was administered to rats at a high dose for 4 weeks. Humans were treated with therapeutic doses of rosuvastatin or atorvastatin for 6 weeks. Platelet mitochondrial respiration was measured using high-resolution respirometry. In rats, a significantly lower physiological respiratory rate was found in intact platelets of simvastatin-treated rats compared to controls. In humans, no significant changes in mitochondrial respiration were detected in intact platelets; however, decreased complex I-linked respiration was observed after statin treatment in permeabilized platelets. We propose that the small in vivo effect of statins on platelet energy metabolism can be attributed to drug effects on complex I of the electron transport system. Both intact and permeabilized platelets can be used as a readily available biological model to study changes in cellular energy metabolism in patients treated with statins.

Coenzyme Q10 concentration in plasma and blood cells of juvenile patients hospitalized for anorexia nervosa

The antioxidant status of coenzyme Q10 (CoQ10) was investigated in plasma, erythrocytes, and platelets of juvenile patients with anorexia nervosa. Blood for analysis of the CoQ10 status was taken from 16 juvenile patients suffering from anorexia nervosa (restricting form) at the time point of admission to the hospital and at discharge after about 12 weeks. Plasma and blood cells isolated by a density gradient were stored at -84 °C until analysis. CoQ10 concentration and redox status were measured by high pressure liquid chromatography with electrochemical detection and internal standardization. The improvement of physical health during the hospital refeeding process was followed up by the body mass index (BMI). The antioxidant status of plasma CoQ10 in juvenile patients suffering from anorexia nervosa indicated no abnormalities in comparison to healthy controls. However, the decreased concentration of CoQ10 observed in platelets at the time point of hospital admission may represent mitochondrial CoQ10 depletion. This initial deficit improved during the hospital refeeding process. The platelet CoQ10 concentration showed a positive correlation to the BMI of the patients.