Analyzing mitochondrial function in human peripheral blood mononuclear cells

Peripheral blood mononuclear cell mitochondrial enzyme activity in calves is associated with average daily gain, reproductive outcomes, lactation performance, and survival

Mitochondria are central to metabolism and are the primary energy producers for all biosynthesis. The objective of this study was to determine if the mitochondrial enzyme activity of peripheral blood mononuclear cells in heifers was associated with average daily gain, reproductive outcomes, first-lactation milk production, and survival. Twenty-three Holstein and 23 Jersey heifer calves were enrolled, and blood and body weight data were collected at 1, 2, 8, 36, 52, and 110 wk of age. Respiratory and fecal scores were recorded daily for the first 30 d of life. Milk production data were collected from herd management software through first lactation and health events were tracked to the fourth lactation on surviving animals. Mitochondrial isolation and enzyme activities for citrate synthase, complex I, complex IV, and complex V were determined using kits from Abcam. Data were analyzed using GLM and the Logistic procedure of SAS (version 9.4, SAS Institute Inc.). Multivariate regression analyses were conducted to determine if calf mitochondrial enzymatic activity and covariate health indices (fecal and respiratory scores, number of treatments, hematology) were associated with average daily gain (8, 36, 52, and 110 wk), lactation performance (milk yield, fat yield, solids yield, energy-corrected milk, 305-d mature equivalent, and relative value), and reproduction (age at first service, age at first conception, age at first calving, and number of services). For Holsteins and Jerseys, mitochondrial enzyme activities and health indices were correlated with all average daily gain and milk production outcomes (R2 ≥ 0.63 and R2 ≥ 0.45, respectively). Reproduction outcomes were correlated with body weight gain, mitochondrial function, and red blood cell traits for Holsteins and Jerseys (R2 ≥ 0.47 and R2 ≥ 0.55, respectively). Logistic regression analyses were performed to determine if early-life enzymatic activity affected survival outcomes in the herd. Calves below the median for complex V enzyme activity at 1 wk were more likely to be removed from the herd compared with calves above the median by lactation 1, 2, 3, and 4 (odds ratio = 4.7, 7.7, 7.0, and 6.9, respectively). Calves below the median for the difference in hematocrit from 2 to 1 wk were more likely to be removed from the herd compared with calves above the median by lactation 1, 2, 3, and 4 (odds ratio = 13, 10, 5.2, and 4.7, respectively). These findings suggest that predictions of cow performance could be improved by considering the effect of early-life mitochondrial enzymatic activity and health indices.

Host mitochondria: more than an organelle in SARS-CoV-2 infection

Since December 2019, the world has been facing viral pandemic called COVID-19 (Coronavirus disease 2019) caused by a new beta-coronavirus named severe acute respiratory syndrome coronavirus-2, or SARS-CoV-2. COVID-19 patients may present with a wide range of symptoms, from asymptomatic to requiring intensive care support. The severe form of COVID-19 is often marked by an altered immune response and cytokine storm. Advanced age, age-related and underlying diseases, including metabolic syndromes, appear to contribute to increased COVID-19 severity and mortality suggesting a role for mitochondria in disease pathogenesis. Furthermore, since the immune system is associated with mitochondria and its damage-related molecular patterns (mtDAMPs), the host mitochondrial system may play an important role during viral infections. Viruses have evolved to modulate the immune system and mitochondrial function for survival and proliferation, which in turn could lead to cellular stress and contribute to disease progression. Recent studies have focused on the possible roles of mitochondria in SARS-CoV-2 infection. It has been suggested that mitochondrial hijacking by SARS-CoV-2 could be a key factor in COVID-19 pathogenesis. In this review, we discuss the roles of mitochondria in viral infections including SARS-CoV-2 infection based on past and present knowledge. Paying attention to the role of mitochondria in SARS-CoV-2 infection will help to better understand the pathophysiology of COVID-19 and to achieve effective methods of prevention, diagnosis, and treatment.

Sepsis-induced mitochondrial dysfunction: A narrative review

Sepsis represents a deranged and exaggerated systemic inflammatory response to infection and is associated with vascular and metabolic abnormalities that trigger systemic organic dysfunction. Mitochondrial function has been shown to be severely impaired during the early phase of critical illness, with a reduction in biogenesis, increased generation of reactive oxygen species and a decrease in adenosine triphosphate synthesis of up to 50%. Mitochondrial dysfunction can be assessed using mitochondrial DNA concentration and respirometry assays, particularly in peripheral mononuclear cells. Isolation of monocytes and lymphocytes seems to be the most promising strategy for measuring mitochondrial activity in clinical settings because of the ease of collection, sample processing, and clinical relevance of the association between metabolic alterations and deficient immune responses in mononuclear cells. Studies have reported alterations in these variables in patients with sepsis compared with healthy controls and non-septic patients. However, few studies have explored the association between mitochondrial dysfunction in immune mononuclear cells and unfavorable clinical outcomes. An improvement in mitochondrial parameters in sepsis could theoretically serve as a biomarker of clinical recovery and response to oxygen and vasopressor therapies as well as reveal unexplored pathophysiological mechanistic targets. These features highlight the need for further studies on mitochondrial metabolism in immune cells as a feasible tool to evaluate patients in intensive care settings. The evaluation of mitochondrial metabolism is a promising tool for the evaluation and management of critically ill patients, especially those with sepsis. In this article, we explore the pathophysiological aspects, main methods of measurement, and the main studies in this field.

DRP1 mutations associated with EMPF1 encephalopathy alter mitochondrial membrane potential and metabolic programs

Mitochondria and peroxisomes are dynamic signaling organelles that constantly undergo fission, driven by the large GTPase dynamin-related protein 1 (DRP1; encoded by DNM1L). Patients with de novo heterozygous missense mutations in DNM1L present with encephalopathy due to defective mitochondrial and peroxisomal fission (EMPF1) - a devastating neurodevelopmental disease with no effective treatment. To interrogate the mechanisms by which DRP1 mutations cause cellular dysfunction, we used human-derived fibroblasts from patients who present with EMPF1. In addition to elongated mitochondrial morphology and lack of fission, patient cells display lower coupling efficiency, increased proton leak and upregulation of glycolysis. Mitochondrial hyperfusion also results in aberrant cristae structure and hyperpolarized mitochondrial membrane potential. Peroxisomes show a severely elongated morphology in patient cells, which is associated with reduced respiration when cells are reliant on fatty acid oxidation. Metabolomic analyses revealed impaired methionine cycle and synthesis of pyrimidine nucleotides. Our study provides insight into the role of mitochondrial dynamics in cristae maintenance and the metabolic capacity of the cell, as well as the disease mechanism underlying EMPF1.

Platelet-Acute Leukemia Interactions

Acute leukemia (AL) is a hematological malignancy with high morbidity and mortality that is caused by abnormal hematopoietic stem cells. AL can change the parameters, quality, and function of platelets through numerous mechanisms, resulting in bleeding and even death in AL patients. Hence, AL patients are often clinically treated using normal platelet transfusion. However, studies have found that platelets can also affect AL cells. This review discusses the changes occurring in platelet count, mean platelet volume, platelet distribution width, reticulated platelets, platelet membrane glycoprotein, platelet aggregation, and activation in AL patients, the causes of these changes, and the possible significance of these changes for patient prognosis. The effects of platelets on the proliferation and drug resistance of AL cells are also discussed.

Dichloroacetate improves mitochondrial function, physiology, and morphology in FBXL4 disease models

Pathogenic variants in the human F-box and leucine-rich repeat protein 4 (FBXL4) gene result in an autosomal recessive, multisystemic, mitochondrial disorder involving variable mitochondrial depletion and respiratory chain complex deficiencies with lactic acidemia. As no FDA-approved effective therapies for this disease exist, we sought to characterize translational C. elegans and zebrafish animal models, as well as human fibroblasts, to study FBXL4^–/– disease mechanisms and identify preclinical therapeutic leads. Developmental delay, impaired fecundity and neurologic and/or muscular activity, mitochondrial dysfunction, and altered lactate metabolism were identified in fbxl-1(ok3741) C. elegans. Detailed studies of a PDHc activator, dichloroacetate (DCA), in fbxl-1(ok3741)C. elegans demonstrated its beneficial effects on fecundity, neuromotor activity, and mitochondrial function. Validation studies were performed in fbxl4^sa12470 zebrafish larvae and in FBXL4^–/– human fibroblasts; they showed DCA efficacy in preventing brain death, impairment of neurologic and/or muscular function, mitochondrial biochemical dysfunction, and stress-induced morphologic and ultrastructural mitochondrial defects. These data demonstrate that fbxl-1(ok3741) C. elegans and fbxl4^sa12470 zebrafish provide robust translational models to study mechanisms and identify preclinical therapeutic candidates for FBXL4^–/– disease. Furthermore, DCA is a lead therapeutic candidate with therapeutic benefit on diverse aspects of survival, neurologic and/or muscular function, and mitochondrial physiology that warrants rigorous clinical trial study in humans with FBXL4^–/– disease.

Peripheral blood mononuclear cell mitochondrial enzyme activity is associated with parity and lactation performance in early lactation Holstein dairy cows

Mitochondria are central to metabolism and are the primary energy producers for all biosynthesis, including lactation. The objectives of this study were to determine if high- and low-producing dairy cows exhibit differences in peripheral blood mononuclear cell mitochondrial enzyme activities of citrate synthase, complex I, complex IV, and complex V during early lactation and, thus, to determine whether those differences were related to differences in lactation performance in the dairy cow. Fifty-six Holstein cows were assigned to 1 of 4 groups: (1) primiparous high, (2) primiparous low, (3) multiparous high, or (4) multiparous low. Primiparous and multiparous cows were analyzed separately. Then, cows were divided into high or low production groups for each production parameter [peak milk, average milk, energy-corrected milk (ECM), fat-corrected milk (FCM), milk lactose, milk fat, milk protein, total solids (TS), solids-not-fat, feed efficiency, and somatic cell count (SCC)]. For all data analysis, production parameters are expressed as yields (kg/d) and SCC (10³ cells/mL). High and low production groups were defined by their respective mean production parameters for the 56 cows, with below average cows defined as low and above average cows defined as high. Whole blood samples were collected at one time point, approximately 70 d in milk at 0800 h, and processed for crude mitochondrial extracts from peripheral blood mononuclear cells to determine the activity rates of mitochondrial enzymes. Milk samples were collected 9 times (3 d, 3 times per d) during the week of blood collection and analyzed for major components (fat, protein, lactose, TS, and SCC). Multiparous cows had lower citrate synthase activity than primiparous cows across all production parameters. High-producing cows had greater complex I activity for peak milk, milk yield, ECM, FCM, milk fat, TS, and feed efficiency, and greater complex V activity for ECM, FCM, milk lactose, milk fat, and TS across parities. These findings imply that the most influential respiratory chain enzymes on the level of milk production are those responsible for electron transport chain initialization and ATP production.

Assessment of mitochondrial respiratory capacity using minimally invasive and noninvasive techniques in persons with spinal cord injury

Purpose

Muscle biopsies are the gold standard to assess mitochondrial respiration; however, biopsies are not always a feasible approach in persons with spinal cord injury (SCI). Peripheral blood mononuclear cells (PBMCs) and near-infrared spectroscopy (NIRS) may alternatively be predictive of mitochondrial respiration. The purpose of the study was to evaluate whether mitochondrial respiration of PBMCs and NIRS are predictive of respiration of permeabilized muscle fibers after SCI.

Methods

Twenty-two individuals with chronic complete and incomplete motor SCI between 18–65 years old were recruited to participate in the current trial. Using high-resolution respirometry, mitochondrial respiratory capacity was measured for PBMCs and muscle fibers of the vastus lateralis oxidizing complex I, II, and IV substrates. NIRS was used to assess mitochondrial capacity of the vastus lateralis with serial cuff occlusions and electrical stimulation.

Results

Positive relationships were observed between PBMC and permeabilized muscle fibers for mitochondrial complex IV (r = 0.86, P < 0.0001). Bland-Altman displayed agreement for complex IV (MD = 0.18, LOA = -0.86 to 1.21), between PBMCs and permeabilized muscles fibers. No significant relationships were observed between NIRS mitochondrial capacity and respiration in permeabilized muscle fibers.

Conclusions

This is the first study to explore and support the agreement of less invasive clinical techniques for assessing mitochondrial respiratory capacity in individuals with SCI. The findings will assist in the application of PBMCs as a viable alternative for assessing mitochondrial health in persons with SCI in future clinical studies.

Assessment of Platelet Mitochondrial Respiration in a Pediatric Population: A Pilot Study in Healthy Children and Children with Acute Lymphoblastic Leukemia

Characterization of mitochondrial respiration in peripheral blood cells has recently emerged as a potential biomarker for the assessment of the severity of hematological malignancies (HM) in adults. Whether changes in platelet respiratory function occur in children with or without HM it is unknown. The present pilot study was double-aimed: (i) to investigate whether platelet respiration is age-dependent in non-HM children and (ii) to assess the platelet mitochondrial respiration in children with newly diagnosed acute lymphoblastic leukemia (ALL). Blood samples obtained from age-grouped children (10–11, 13–14 and 16–17 years) with non-HM and children with ALL (10–11 years) were used to isolate platelets via differential centrifugation. High-resolution respirometry studies of isolated platelets were performed according to a protocol adapted to evaluate complex I and II-supported respiration. An age-related decrease in respiration was observed in the non-HM pediatric population and had comparable values for the 13–14 and 16–17 years. groups. In children with ALL, a significant increase in C I-supported active respiration and decrease in maximal noncoupled respiration were found at the disease onset. In conclusion, in a pediatric population, platelet mitochondrial respiration is age-dependent. Platelet respiratory dysfunction occurs in children with newly-diagnosed ALL, an observation that warrants further investigation of this change as a disease biomarker.

Impact of acute exercise on peripheral blood mononuclear cells nutrient sensing and mitochondrial oxidative capacity in healthy young adults

Regular exercise is associated with changes in peripheral blood mononuclear cell (PBMC) proportions that have enhanced effector functions in young and old adults; however, the effects of acute exercise on PBMC nutrient sensors and metabolic function in active young adults is unknown. To fill this gap, activation status and nutrient-sensing mechanisms of PBMCs isolated from 21 healthy active adults (20-35 yr; 36.5 ± 6.3 V̇O2peak ) were characterized before and after 30 min of moderate-to-vigorous cycling (65%-75% V̇O2peak ). In addition, changes in PBMC mitochondrial respiratory function in response to exercise were assessed using high-resolution respirometry. There was an increase in the number of activated CD69+/CD4 (79% increase) and CD69+/CD8 (166% increase) T-cells in response to the acute bout of exercise, while the nutrient-sensing mechanisms remained unchanged. PBMC mitochondrial respiration did not increase on a cell-per-cell basis, however, mitochondrial oxidative capacity (OXPHOS) increased at the tissue level (18.6 pmol/(s*ml blood) versus 29.3 pmol/(s*ml blood); p < 0.05) in response to acute exercise. Thus, this study shows that acute exercise preferentially mobilizes activated T-cells while concomitantly increasing PBMC mitochondrial oxidative capacity at the tissue level, rather than acutely changing mitochondrial oxidative capacity at the cellular level in young adults.

Blood biomarkers for assessment of mitochondrial dysfunction: An expert review

Although mitochondrial dysfunction is the known cause of primary mitochondrial disease, mitochondrial dysfunction is often difficult to measure and prove, especially when biopsies of affected tissue are not available. In order to identify blood biomarkers of mitochondrial dysfunction, we reviewed studies that measured blood biomarkers in genetically, clinically or biochemically confirmed primary mitochondrial disease patients. In this way, we were certain that there was an underlying mitochondrial dysfunction which could validate the biomarker. We found biomarkers of three classes: 1) functional markers measured in blood cells, 2) biochemical markers of serum/plasma and 3) DNA markers. While none of the reviewed single biomarkers may perfectly reveal all underlying mitochondrial dysfunction, combining biomarkers that cover different aspects of mitochondrial impairment probably is a good strategy. This biomarker panel may assist in the diagnosis of primary mitochondrial disease patients. As mitochondrial dysfunction may also play a significant role in the pathophysiology of multifactorial disorders such as Alzheimer's disease and glaucoma, the panel may serve to assess mitochondrial dysfunction in complex multifactorial diseases as well and enable selection of patients who could benefit from therapies targeting mitochondria.

Metabolic Changes in Peripheral Blood Mononuclear Cells Isolated From Patients With End Stage Renal Disease

As numerous complex pathologies stem from cellular energy dysfunction, we aimed to elucidate mitochondrial function and associated stress pathologies in kidney disease in a cohort of hemodialysis patients with end-stage kidney disease (ESKD). The bioenergetics study was conducted using peripheral blood mononuclear cells (PBMCs) of ESKD patients (n = 29) and healthy controls (no ESKD, n = 10). PBMCs were isolated from whole blood and seeded into assay plates to detect changes in oxidative phosphorylation and glycolysis. The bioenergetics analysis (i.e., mitochondrial stress test) was performed using Seahorse XFe24 flux analyzer. We observed significant reduction in mitochondrial respiration in patient PBMCs in terms of fundamental bioenergetics parameters such as basal respiration, ATP turnover, maximal respiration and spare respiratory capacity. These findings were correlated with the expression levels of proteins coordinating cellular energy status and regulating mitochondrial dynamics. Our data demonstrates an association between mitochondrial oxygen consumption of PBMCs and ESKD. AMPK activity, its downstream effector PGC-1α and mitochondrial fission/fusion proteins are partially responsible for the decrease in oxidative phosphorylation of PBMCs isolated from ESKD patients. We propose a link between mitochondrial dysfunction and ESKD and a role for mitochondria as a potential site for therapeutic interventions.

Differential Levels of Endoplasmic Reticulum Stress in Peripheral Blood Mononuclear Cells from Patients with Sudden Sensorineural Hearing Loss

Background

Sudden sensorineural hearing loss (SSNHL) is currently treated with a combination of drugs, predominantly with glucocorticoids (GCs). However, the mechanisms of action of GCs in SSNHL are unknown. This study aimed to analyze the role of endoplasmic reticulum stress (ERS) in SSNHL pathogenesis and prognosis.

Material/Methods

In this study, we evaluated the expression and activation status of the protein kinase RNA-like endoplasmic reticulum kinase (PERK)-C/EBP homologous protein (CHOP) pathway in peripheral blood mononuclear cells (PBMCs) from patients with SSNHL and compared them with those in healthy controls. We also compared differences in expression of activating transcription factor 4 (ATF4) and CHOP before and after glucocorticoid treatment in patients with improved and unimproved SSNHL.

Results

Treatment with GCs significantly improved hearing in 55% of patients with SSNHL. Levels of phosphorylated PERK (p-PERK) and phosphorylated eukaryotic initiation factor 2α were increased in PBMCs from patients with SSNHL compared with healthy controls. ATF4 and CHOP expression were also significantly elevated. After treatment, the amount of ATF4 and CHOP proteins in PBMCs in the patients whose SSNHL improved was significantly reduced compared with the levels measured before treatment in all patients with SSNHL. The expression of the ATF4 and CHOP proteins in PBMCs in the unimproved group, however, was not significantly changed relative to pretreatment levels.

Conclusions

ERS may play a significant role in the pathogenesis of SSNHL, and the responsiveness of the condition to GC-mediated mitigation of ERS may be one of the key factors that affect patient prognosis.

New Insights into the Implication of Mitochondrial Dysfunction in Tissue, Peripheral Blood Mononuclear Cells, and Platelets during Lung Diseases

Lung diseases such as chronic obstructive pulmonary disease, asthma, pulmonary arterial hypertension, or idiopathic pulmonary fibrosis are major causes of morbidity and mortality. Complex, their physiopathology is multifactorial and includes lung mitochondrial dysfunction and enhanced reactive oxygen species (ROS) release, which deserves increased attention. Further, and importantly, circulating blood cells (peripheral blood mononuclear cells-(PBMCs) and platelets) likely participate in these systemic diseases. This review presents the data published so far and shows that circulating blood cells mitochondrial oxidative capacity are likely to be reduced in chronic obstructive pulmonary disease (COPD), but enhanced in asthma and pulmonary arterial hypertension in a context of increased oxidative stress. Besides such PBMCs or platelets bioenergetics modifications, mitochondrial DNA (mtDNA) changes have also been observed in patients. These new insights open exciting challenges to determine their role as biomarkers or potential guide to a new therapeutic approach in lung diseases.

Platelet Mitochondrial Respiration, Endogenous Coenzyme Q10 and Oxidative Stress in Patients with Chronic Kidney Disease

Chronic kidney disease (CKD) is characterized by a progressive loss of renal function and a decrease of glomerular filtration rate. Reduced mitochondrial function, coenzyme Q₁₀ (CoQ₁₀), and increased oxidative stress in patients with CKD contribute to the disease progression. We tested whether CoQ₁₀ levels, oxidative stress and platelet mitochondrial bioenergetic function differ between groups of CKD patients.

METHODS

Twenty-seven CKD patients were enrolled in this trial, 17 patients had arterial hypertension (AH) and 10 patients had arterial hypertension and diabetes mellitus (AH and DM). The control group consisted of 12 volunteers. A high-resolution respirometry (HRR) method was used for the analysis of mitochondrial bioenergetics in platelets, and an HPLC method with UV detection was used for CoQ₁₀ determination in platelets, blood, and plasma. Oxidative stress was determined as thiobarbituric acid reactive substances (TBARS).

RESULTS

Platelets mitochondrial respiration showed slight, not significant differences between the groups of CKD patients and control subjects. The oxygen consumption by intact platelets positively correlated with the concentration of CoQ₁₀ in the platelets of CKD patients.

CONCLUSION

A decreased concentration of CoQ₁₀ and oxidative stress could contribute to the progression of renal dysfunction in CKD patients. The parameters of platelet respiration assessed by high-resolution respirometry can be used only as a weak biological marker for mitochondrial diagnosis and therapy monitoring in CKD patients.

Peripheral Blood Mononuclear Cells and Platelets Mitochondrial Dysfunction, Oxidative Stress, and Circulating mtDNA in Cardiovascular Diseases

Cardiovascular diseases (CVDs) are devastating disorders and the leading cause of mortality worldwide. The pathophysiology of cardiovascular diseases is complex and multifactorial and, in the past years, mitochondrial dysfunction and excessive production of reactive oxygen species (ROS) have gained growing attention. Indeed, CVDs can be considered as a systemic alteration, and understanding the eventual implication of circulating blood cells peripheral blood mononuclear cells (PBMCs) and or platelets, and particularly their mitochondrial function, ROS production, and mitochondrial DNA (mtDNA) releases in patients with cardiac impairments, appears worthwhile. Interestingly, reports consistently demonstrate a reduced mitochondrial respiratory chain oxidative capacity related to the degree of CVD severity and to an increased ROS production by PBMCs. Further, circulating mtDNA level was generally modified in such patients. These data are critical steps in term of cardiac disease comprehension and further studies are warranted to challenge the possible adjunct of PBMCs’ and platelets’ mitochondrial dysfunction, oxidative stress, and circulating mtDNA as biomarkers of CVD diagnosis and prognosis. This new approach might also allow further interesting therapeutic developments.

Cancer‑related fatigue during combined treatment of androgen deprivation therapy and radiotherapy is associated with mitochondrial dysfunction

Combined androgen deprivation therapy (ADT) and radiation therapy (RT) is the standard of care treatment for non-metastatic prostate cancer (NMPC). Despite the efficacy, treatment-related symptoms including fatigue greatly reduce the quality of life of cancer patients. The goal of the study is to examine the influence of combined ADT/RT on fatigue and understand its underlying mechanisms. A total of 64 participants with NMPC were enrolled. Fatigue was assessed using the Functional Assessment of Cancer Therapy-Fatigue. Mitochondrial function parameters were measured as oxygen consumption from peripheral blood mononuclear cells (PBMCs) extracted from participants' whole blood. An ADT/RT-induced fatigue mouse model was developed, with fatigue measured as a reduction in voluntary wheel-running activity (VWRA) in 54 mice. Mitochondrial function was assessed in the ADT/RT mouse brains using western blot analysis of glucose transporter 4 (GLUT4) and transcription factor A, mitochondrial (TFAM). The results demonstrated that fatigue in the ADT group was exacerbated during RT compared with the non-ADT group. This effect was specific to fatigue, as depressive symptoms were unaffected. PBMCs of fatigued subjects exhibited decreased ATP coupling efficiency compared to non-fatigued subjects, indicative of mitochondrial dysfunction. The ADT/RT mice demonstrated the synergistic effect of ADT and RT in decreasing VWRA. Brain tissues of ADT/RT mice exhibited decreased levels of GLUT4 and TFAM suggesting that impaired neuronal metabolic homeostasis may contribute to fatigue pathogenesis. In conclusion, these findings suggest that fatigue induced by ADT/RT may be attributable to mitochondrial dysfunction both peripherally and in the central nervous system (CNS). The synergistic effect of ADT/RT is behaviorally reproducible in a mouse model and its mechanism may be related to bioenergetics in the CNS.

Relationships between expression of BCS1L, mitochondrial bioenergetics, and fatigue among patients with prostate cancer

Introduction: Cancer-related fatigue (CRF) is the most debilitating symptom with the greatest adverse side effect on quality of life. The etiology of this symptom is still not understood. The purpose of this study was to examine the relationship between mitochondrial gene expression, mitochondrial oxidative phosphorylation, electron transport chain complex activity, and fatigue in prostate cancer patients undergoing radiotherapy (XRT), compared to patients on active surveillance (AS).

Methods: The study used a matched case–control and repeated-measures research design. Fatigue was measured using the revised Piper Fatigue Scale from 52 patients with prostate cancer. Mitochondrial oxidative phosphorylation, electron-transport chain enzymatic activity, and BCS1L gene expression were determined using patients’ peripheral mononuclear cells. Data were collected at three time points and analyzed using repeated measures ANOVA.

Results: The fatigue score was significantly different over time between patients undergoing XRT and AS (P<0.05). Patients undergoing XRT experienced significantly increased fatigue at day 21 and day 42 of XRT (P<0.01). Downregulated mitochondrial gene (BC1, ubiquinol-cytochrome c reductase, synthesis-like, BCS1L, P<0.05) expression, decreased OXPHOS-complex III oxidation (P<0.05), and reduced activity of complex III were observed over time in patients with XRT. Moreover, increased fatigue was significantly associated with downregulated BCS1L and decreased complex III oxidation in patients undergoing XRT.

Conclusion: Our results suggest that BCS1L and complex III in mitochondrial mononuclear cells are potential biomarkers and feasible therapeutic targets for acute XRT-induced fatigue in this clinical population.

Assessment of platelet respiration as emerging biomarker of disease

Mitochondrial dysfunction is currently acknowledged as a central pathomechanism of most common diseases of the 21(st) century. Recently, the assessment of the bioenergetic profile of human peripheral blood cells has emerged as a novel research field with potential applications in the development of disease biomarkers. In particular, platelets have been successfully used for the ex vivo analysis of mitochondrial respiratory function in several acute and chronic pathologies. An increasing number of studies support the idea that evaluation of the bioenergetic function in circulating platelets may represent the peripheral signature of mitochondrial dysfunction in metabolically active tissues (brain, heart, liver, skeletal muscle). Accordingly, impairment of mitochondrial respiration in peripheral platelets might have potential clinical applicability as a diagnostic and prognostic tool as well as a biomarker in treatment monitoring. The aim of this minireview is to summarize current information in the field of platelet mitochondrial dysfunction in both acute and chronic diseases.

Integrated mitochondrial function and cancer-related fatigue in men with prostate cancer undergoing radiation therapy

Introduction

Fatigue experienced by cancer patients is one of the most common symptoms with the greatest adverse effect on quality of life, but arguably the least understood. The purpose of this study was to explore changes in integrated mitochondrial function and fatigue in non-metastatic prostate cancer patients receiving localized radiation therapy (XRT).

Materials and methods

We proposed a mitochondrial bioenergetics mechanism of radiation-induced fatigue linking impaired oxidative phosphorylation (OXPHOS) through complex III and decreased adenosine triphosphate (ATP) production as consequences of XRT. Integrated mitochondrial function was measured as mitochondrial OXPHOS from patients’ peripheral blood mononuclear cells. Fatigue was measured using the revised Piper Fatigue Scale. Data were collected before (day 0) and at day 21 of XRT.

Results

At day 21 of XRT, fatigue symptom intensified in 15 prostate cancer patients (P<0.05). Mitochondrial OXPHOS complex III-linked and uncoupled complex III rates were significantly decreased in mononuclear cells at day 21 during XRT compared to that before XRT (P<0.05). Additionally, increased fatigue appeared to be associated with decreased OXPHOS complex III-linked respiration in patients undergoing XRT.

Conclusion

Fatigue was associated with OXPHOS complex III-linked oxidation and a defect in oxidation starting at complex III in mononuclear cell mitochondria was revealed at day 21 of XRT in 15 prostate cancer patients. Complex III is a potential target for pharmacological and, in particular, nutraceutical interventions, eg, Q10, for design of interventions for CRF.

Analysis of mitochondrial respiratory function in tissue biopsies and blood cells

PURPOSE OF REVIEW

The review provides an overview on latest methodological strategies to assess mitochondrial respiratory function in tissue biopsies or blood cells. In addition, it summarizes the recent literature related to this topic.

RECENT FINDINGS

Today, the study of mitochondrial function in key metabolic active tissues has been become more relevant, with increasing focus in clinical applications. In addition, assessment of mitochondrial function in blood cells by respirometry might be a sensitive biomarker of disease progression. High-Resolution Respirometry provides a modern tool to study mitochondrial respiratory physiology which allows direct measurement of cellular metabolic function during health and disease. Moreover, standard operating procedures are required regarding instrumental settings, sample collection and preparation, protocol design and respirometric data analysis of mitochondrial respiratory function in tissue biopsies (such as skeletal muscle, liver and adipose tissue), as well as isolated blood cells.

SUMMARY

Mitochondrial function is a key factor in many metabolic diseases. Although various analytical approaches are available, certain well-established protocols for isolated mitochondria are limited for the analysis of mitochondrial function in tissue biopsies or blood cells. Thus, cautious considerations in selecting appropriate protocols and analytical endpoints are crucial for the interpretation of the gained data and to draw robust conclusions.

Mitochondrial DNA copy number in peripheral blood: a potential non-invasive biomarker for female subfertility

PURPOSE

Low mitochondrial DNA (mtDNA) content in oocytes and in cumulus cells is an indicator of poor oocyte quality. Moreover, initial evidence showed a correlation between mtDNA content in cumulus cells and mtDNA copy number in peripheral blood cells. On these bases, we deemed of interest investigating the correlation between mtDNA copy number in peripheral blood and natural fecundity.

METHODS

This is a nested case-control study drawn from a prospective cohort of pregnant women referred for routine first trimester screening for aneuploidies (from 11 + 0 to 12 + 6 weeks of gestation) between January 2012 and March 2013 at the "Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico" of Milan, Italy. Cases were subfertile women who attempted to become pregnant for 12-24 months. Controls were the two subsequently age-matched women who became pregnant in less than 1 year. MtDNA was quantified using real-time PCR and normalized to nuclear DNA.

RESULTS

One hundred and four subfertile women and 208 controls were selected. The median (IQR) mtDNA copy number was 95 (73-124) and 145 (106-198), respectively (p < 0.001). The area under the ROC curve was 0.73 (95% CI 0.67-0.79) (p < 0.001). The Youden index was 105 mtDNA copy number. The crude OR for subfertility in women with mtDNA copy number below this threshold was 5.72 (95% CI 3.43-9.55). The accuracy of mtDNA copy number assessment in peripheral blood progressively decreased with increasing female age.

CONCLUSIONS

Low mtDNA copy number in peripheral blood is associated with an increased risk of subfertility and may represent a biomarker of natural fecundity.