Mitochondrial Function in Peripheral Blood Mononuclear Cells (PBMC) Is Enhanced, Together with Increased Reactive Oxygen Species, in Severe Asthmatic Patients in Exacerbation

Low energy availability increases immune cell formation of reactive oxygen species and impairs exercise performance in female endurance athletes

INTRODUCTION

The effects of low energy availability (LEA) on the immune system are poorly understood. This study examined the effects of 14 days of LEA on immune cell redox balance and inflammation at rest and in response to acute exercise, and exercise performance in female athletes.

METHODS

Twelve female endurance athletes (age: 26.8 ± 3.4 yrs, maximum oxygen uptake (V˙O2max): 55.2 ± 5.1 mL × min-1 × kg-1) were included in a randomized, single-blinded crossover study. They were allocated to begin with either 14 days of optimal energy availability diet (OEA, 52 ± 2 kcal × kg fat free mass (FFM)-1 × day-1) or LEA diet (22 ± 2 kcal × kg FFM-1 × day-1), followed by 3 days of refueling (OEA) with maintained training volume. Peripheral blood mononuclear cells (PBMCs) were isolated, and plasma obtained at rest before and after each dietary period. The PBMCs were used for analysis of mitochondrial respiration and H2O2 emission and specific proteins. Exercise performance was assessed on cycle by a 20-min time trial and time to exhaustion at an intensity corresponding to ∼110 % V˙O2max).

RESULTS

LEA was associated with a 94 % (P = 0.003) increase in PBMC NADPH oxidase 2 protein content, and a 22 % (P = 0.013) increase in systemic cortisol. LEA also caused an alteration of several inflammatory related proteins (P < 0.05). Acute exercise augmented H2O2 emission in PBMCs (P < 0.001) following both OEA and LEA, but to a greater extent following LEA. LEA also reduced the mobilization of white blood cells with acute exercise. After LEA, performance was reduced in both exercise tests (P < 0.001), and the reduced time trial performance remained after the 3 days of refueling (P < 0.001).

CONCLUSION

14 days of LEA in female athletes increased cortisol levels and had a pronounced effect on the immune system, including increased capacity for ROS production, altered plasma inflammatory proteome and lowered exercise induced mobilization of leukocytes. Furthermore, LEA resulted in a sustained impairment in exercise performance.

The role of mitochondria in eosinophil function: implications for severe asthma pathogenesis

Mitochondria are key metabolic hubs involved in cellular energy production and biosynthesis. ATP is generated primarily by glucose and fatty acid oxidation through the tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS) in the mitochondria. During OXPHOS there is also production of reactive oxygen species (ROS), which are involved in the regulation of cellular function. Mitochondria are also central in the regulating cell survival and death, particularly in the intrinsic apoptosis pathway. Severe asthma is a heterogeneous disease driven by various immune mechanisms. Severe eosinophilic asthma entails a type 2 inflammatory response and peripheral and lung eosinophilia, associated with severe airflow obstruction, frequent exacerbations and poor response to treatment. Mitochondrial dysfunction and altered metabolism have been observed in airway epithelial and smooth muscle cells from patients with asthma. However, the role of mitochondria in the development of eosinophilia and eosinophil-mediated inflammation in severe asthma is unknown. In this review, we discuss the currently limited literature on the role of mitochondria in eosinophil function and how it is regulated by asthma-relevant cytokines, including interleukin (IL)-5 and granulocyte-macrophage colony-stimulating factor (GM-CSF), as well as by corticosteroid drugs. Moreover, we summarise the evidence on the role of mitochondria in the regulation of eosinophils apoptosis and eosinophil extracellular trap formation. Finally, we discuss the possible role of altered mitochondrial function in eosinophil dysfunction in severe asthma and suggest possible research avenues in order to better understand their role in disease pathogenesis, and identify novel therapeutic targets.

Association of transient mitochondrial functional impairment with acute heat exposure in children from Muzaffarpur region of Bihar, India

Over the past several years, the Muzaffarpur district of Bihar (India) has witnessed recurrent outbreaks of acute encephalitis illness of unknown etiology, called acute encephalitis syndrome (AES) among young children, especially during the peak-summer season. Pesticide exposure, viral encephalitis, and litchi toxin intake have all been postulated as potential sources of the ailment. However, no conclusive etiology for AES has been identified in the affected children. During recent rounds of the outbreak, metabolic abnormalities have been documented in these children, and a direct correlation was observed between higher environmental temperature during the peak-summer month and AES caseload. The clinical and metabolic profiles of these children suggested the possible involvement of mitochondrial dysfunction during heat stress as one of the several contributory factors leading to multisystem metabolic derangement. The present study observed that mitochondrial function parameters such as cell death, mitochondrial membrane potential, oxidative stress, and mitochondrial pathway-related gene expression in peripheral blood mononuclear cells (PBMCs) isolated from children were affected in peak-summer when compared to post-summer months. Similar observations of mitochondrial function parameters along with impaired bioenergetic parameters were demonstrated in the heat-exposed model of PBMCs isolated from healthy adult individuals. In conclusion, the results suggested that there is an association of transient mitochondrial dysfunction when exposed to sustained heat during the summer months. One may consider mitochondrial dysfunction as one of the important factors leading to an outbreak of AES among the children from affected regions though this needs to be substantiated with further studies.

Identification of peripheral vascular function measures and circulating biomarkers of mitochondrial function in patients with mitochondrial disease

The development of pharmacological therapies for mitochondrial diseases is hampered by the lack of tissue-level and circulating biomarkers reflecting effects of compounds on endothelial and mitochondrial function. This phase 0 study aimed to identify biomarkers differentiating between patients with mitochondrial disease and healthy volunteers (HVs). In this cross-sectional case-control study, eight participants with mitochondrial disease and eight HVs matched on age, sex, and body mass index underwent study assessments consisting of blood collection for evaluation of plasma and serum biomarkers, mitochondrial function in peripheral blood mononuclear cells (PBMCs), and an array of imaging methods for assessment of (micro)circulation. Plasma biomarkers GDF-15, IL-6, NT-proBNP, and cTNI were significantly elevated in patients compared to HVs, as were several clinical chemistry and hematology markers. No differences between groups were found for mitochondrial membrane potential, mitochondrial reactive oxygen production, oxygen consumption rate, or extracellular acidification rate in PBMCs. Imaging revealed significantly higher nicotinamide-adenine-dinucleotide-hydrogen (NADH) content in skin as well as reduced passive leg movement-induced hyperemia in patients. This study confirmed results of earlier studies regarding plasma biomarkers in mitochondrial disease and identified several imaging techniques that could detect functional differences at the tissue level between participants with mitochondrial disease and HVs. However, assays of mitochondrial function in PBMCs did not show differences between participants with mitochondrial disease and HVs, possibly reflecting compensatory mechanisms and heterogeneity in mutational load. In future clinical trials, using a mix of imaging and blood-based biomarkers may be advisable, as well as combining these with an in vivo challenge to disturb homeostasis.

Peripheral Blood Mononuclear Cells Mitochondrial Respiration and Superoxide Anion after Heart Transplantation

INTRODUCTION

The mitochondrial function of circulating peripheral blood mononuclear cells (PBMCs) is an interesting new approach to cardiac diseases. Thus, PBMC's mitochondrial respiration decreases in relation to heart failure severity. However, no data are available on heart-transplanted patients (Htx).

POPULATION AND METHODS

We determined PBMCs mitochondrial respiration by high-resolution respirometry (Oroboros Instruments) and superoxide anion production using electron paramagnetic resonance (Bruker-Biospin) in 20 healthy subjects and 20 matched Htx and investigated clinical, biological, echocardiographic, coronarography and biopsy characteristics.

RESULTS

PBMCs mitochondrial respiratory chain complex II respiration was decreased in Htx (4.69 ± 0.84 vs. 7.69 ± 1.00 pmol/s/million cell in controls and Htx patients, respectively; p = 0.007) and complex IV respiration was increased (24.58 ± 2.57 vs. 15.68 ± 1.67 pmol/s/million cell; p = 0.0035). Superoxide anion production was also increased in Htx (1.47 ± 0.10 vs. 1.15 ± 0.10 µmol/min; p = 0.041). The leucocyte-to-lymphocyte ratio was increased in Htx, whom complex II correlated with leucocyte number (r = 0.51, p = 0.02) and with the left ventricular posterior wall peak early diastolic myocardial velocity (r = -0.62, p = 0.005). Complex IV was increased in the two patients with acute rejection and correlated negatively with Htx's isovolumetric relation time (r = -0.45, p = 0.045).

DISCUSSION

Although presenting with normal systolic function, Htx demonstrated abnormal PBMC's mitochondrial respiration. Unlike immunosuppressive therapies, subclinical diastolic dysfunction might be involved in these changes. Additionally, lymphopenia might reduce complex II, and acute rejection enhances complex IV respirations.

CONCLUSION

PBMC's mitochondrial respiration appears modified in Htx, potentially linked to cellular shift, mild diastolic dysfunction and/or acute rejection.

Pathophysiology of Heart Failure: A Role for Peripheral Blood Mononuclear Cells Mitochondrial Dysfunction?

Heart failure (HF) is a leading cause of hospitalization in patients aged more than 65 years and is associated with high mortality rates. A better comprehension of its physiopathology is still needed, and, in addition to neurohormonal systems and sodium glucose co-transporter 2 modulations, recent studies focus on the mitochondrial respiration of peripheral blood circulating cells (PBMCs). Thus, cardiovascular metabolic risk factors and cellular switch with an increased neutrophil/lymphocytes ratio might favor the decreased PBMC mitochondrial respiration observed in relation with HF severity. PBMCs are implicated in the immune system function and mitochondrial dysfunction of PBMC, potentially induced by their passage through a damaged heart and by circulating mitoDAMPs, which can lead to a vicious circle, thus sustaining negative cardiac remodeling during HF. This new approach of HF complex pathophysiology appears to be a promising field of research, and further studies on acute and chronic HF with reduced or preserved LVEF are warranted to better understand whether circulating PBMC mitochondrial function and mitoDAMPs follow-ups in HF patients might show diagnosis, prognosis or therapeutic usefulness.

Mitochondria determine response to anti-programmed cell death protein-1 (anti-PD-1) immunotherapy: An evidence-based hypothesis

Immunotherapy based on programmed cell death protein-1 (PD-1) is a promising approach in oncology. However, a significant fraction of patients remain unresponsive. Therefore, it is imperative to clarify the relevant predictive factors. A decrease in cellular adenosine triphosphate (c-ATP) level can predispose to cellular dysfunction. ATP is a prerequisite for proper T cell migration and activation. Therefore, a decrease in the c-ATP level impairs T cell function and promotes cancer progression. This article gives an overview of the potential predictive factors of PD-1 blockade. Besides, it highlights the pivotal role of mitochondria in response to anti-PD-1 therapies.

Analysis of N15-rat growth hormone after incubation with rat subcutaneous tissue and immune cells using ultra-pressure chromatography-mass spectrometry

Therapeutic proteins (TPs) are exposed to various immune cells like macrophages and neutrophils, especially after subcutaneous (SC) administration. It is well known that the immune cells can generate reactive oxygen species (ROS) and this may lead to oxidation of TPs. The oxidation can occur in the SC tissue after SC administration, during distribution to the immune organs like lymph nodes and spleen, and even in the blood circulation. The oxidation can lead to alteration of their pharmacokinetics and efficacy. Therefore, it is important to study the oxidation of TPs in the biological matrices using ultra-pressure chromatography-mass spectrometry. Rat growth hormone (rGH) was selected as a test protein due to its similarity with human growth hormone (hGH), which is widely used for treatment of growth hormone deficiency. In this manuscript, we have summarized sample processing strategy and ultra-pressure chromatography-mass spectrometry methodology to identify rGH and its degradation products after ex-vivo incubation with rat SC tissue, and in vitro incubation with rat splenocytes and canine peripheral blood mononuclear cells (cPBMCs) as a model foreign host species. We did not observe oxidation of rGH in these biological matrices. This could be due to very minor yields of oxidation products, lack of sensitivity of the mass spectrometry method, loss of protein during sample processing, rapid turnover of oxidized protein or a combination of all factors.

Protective effects of N-acetylcysteine on a chemical-induced murine model of asthma

INTRODUCTION

Oxidative stress is involved in the pathophysiology of inflammatory airway diseases, including asthma. In this study, we elucidated the possible protective effects of the antioxidant N-acetylcysteine (NAC) on a toluene diisocyanate (TDI)-induced murine asthma model.

METHODS

Male BALB/c mice were sensitized and challenged with TDI to generate a chemical-induced asthma model. NAC was given intraperitoneally to mice immediately after each TDI challenge. Airway reactivity to methacholine and bronchoalveolar lavage fluid was analyzed. Lungs were examined by histology.

RESULTS

NAC treatment dramatically reduced the increased airway hyperresponsiveness, inflammatory infiltration, and goblet cell metaplasia in TDI-exposed mice. Numbers of total cells, neutrophils, and eosinophils in the bronchoalveolar lavage fluid of TDI-challenged mice were significantly higher than vehicle control, but the administration of NAC decreased these inflammatory cell counts. TDI exposure led to significantly increased levels of interleukin 4 (IL-4) and IL-5, which were also suppressed by NAC. In addition, diminished lung reduced oxidized glutathione ratio and superoxide dismutase activity were observed after TDI challenge, and these changes were attenuated by NAC.

CONCLUSION

NAC treatment has beneficial effects in TDI-induced asthma.

Mitochondrial Dysfunction in Chronic Respiratory Diseases: Implications for the Pathogenesis and Potential Therapeutics

Mitochondria are indispensable for energy metabolism and cell signaling. Mitochondrial homeostasis is sustained with stabilization of mitochondrial membrane potential, balance of mitochondrial calcium, integrity of mitochondrial DNA, and timely clearance of damaged mitochondria via mitophagy. Mitochondrial dysfunction is featured by increased generation of mitochondrial reactive oxygen species, reduced mitochondrial membrane potential, mitochondrial calcium imbalance, mitochondrial DNA damage, and abnormal mitophagy. Accumulating evidence indicates that mitochondrial dysregulation causes oxidative stress, inflammasome activation, apoptosis, senescence, and metabolic reprogramming. All these cellular processes participate in the pathogenesis and progression of chronic respiratory diseases, including chronic obstructive pulmonary disease, pulmonary fibrosis, and asthma. In this review, we provide a comprehensive and updated overview of the impact of mitochondrial dysfunction on cellular processes involved in the development of these respiratory diseases. This not only implicates mechanisms of mitochondrial dysfunction for the pathogenesis of chronic lung diseases but also provides potential therapeutic approaches for these diseases by targeting dysfunctional mitochondria.

Ozone-Induced Oxidative Stress, Neutrophilic Airway Inflammation, and Glucocorticoid Resistance in Asthma

Despite recent advances in using biologicals that target Th2 pathways, glucocorticoids form the mainstay of asthma treatment. Asthma morbidity and mortality remain high due to the wide variability of treatment responsiveness and complex clinical phenotypes driven by distinct underlying mechanisms. Emerging evidence suggests that inhalation of the toxic air pollutant, ozone, worsens asthma by impairing glucocorticoid responsiveness. This review discusses the role of oxidative stress in glucocorticoid resistance in asthma. The underlying mechanisms point to a central role of oxidative stress pathways. The primary data source for this review consisted of peer-reviewed publications on the impact of ozone on airway inflammation and glucocorticoid responsiveness indexed in PubMed. Our main search strategy focused on cross-referencing "asthma and glucocorticoid resistance" against "ozone, oxidative stress, alarmins, innate lymphoid, NK and γδ T cells, dendritic cells and alveolar type II epithelial cells, glucocorticoid receptor and transcription factors". Recent work was placed in the context from articles in the last 10 years and older seminal research papers and comprehensive reviews. We excluded papers that did not focus on respiratory injury in the setting of oxidative stress. The pathways discussed here have however wide clinical implications to pathologies associated with inflammation and oxidative stress and in which glucocorticoid treatment is essential.

Understanding the Link Between Allergy and Neurodevelopmental Disorders: A Current Review of Factors and Mechanisms

Both allergic diseases and neurodevelopmental disorders are non-communicable diseases (NCDs) that not only impact on the quality of life and but also result in substantial economic burden. Immune dysregulation and inflammation are typical hallmarks in both allergic and neurodevelopmental disorders, suggesting converging pathophysiology. Epidemiological studies provided convincing evidence for the link between allergy and neurodevelopmental diseases such as attention-deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). Possible factors influencing the development of these disorders include maternal depression and anxiety, gestational diabetes mellitus, maternal allergic status, diet, exposure to environmental pollutants, microbiome dysbiosis, and sleep disturbances that occur early in life. Moreover, apart from inflammation, epigenetics, gene expression, and mitochondrial dysfunction have emerged as possible underlying mechanisms in the pathogenesis of these conditions. The exploration and understanding of these shared factors and possible mechanisms may enable us to elucidate the link in the comorbidity.

Intraoperative Perfusion Assessment in Enhanced Reality Using Quantitative Optical Imaging: An Experimental Study in a Pancreatic Partial Ischemia Model

To reduce the risk of pancreatic fistula after pancreatectomy, a satisfactory blood flow at the pancreatic stump is considered crucial. Our group has developed and validated a real-time computational imaging analysis of tissue perfusion, using fluorescence imaging, the fluorescence-based enhanced reality (FLER). Hyperspectral imaging (HSI) is another emerging technology, which provides tissue-specific spectral signatures, allowing for perfusion quantification. Both imaging modalities were employed to estimate perfusion in a porcine model of partial pancreatic ischemia. Perfusion quantification was assessed using the metrics of both imaging modalities (slope of the time to reach maximum fluorescence intensity and tissue oxygen saturation (StO2), for FLER and HSI, respectively). We found that the HSI-StO2 and the FLER slope were statistically correlated using the Spearman analysis (R = 0.697; p = 0.013). Local capillary lactate values were statistically correlated to the HSI-StO2 and to the FLER slope (R = −0.88; p < 0.001 and R = −0.608; p = 0.0074). HSI-based and FLER-based lactate prediction models had statistically similar predictive abilities (p = 0.112). Both modalities are promising to assess real-time pancreatic perfusion. Clinical translation in human pancreatic surgery is currently underway.

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.

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.