The association between cortisol, oxytocin, and immune cell mitochondrial oxygen consumption in postpartum women with childhood maltreatment

Associations between prenatal distress, mitochondrial health, and gestational age: findings from two pregnancy studies in the USA and Turkey

Background

Pregnancy outcomes are influenced by maternal distress but the pathways underlying these effects are still unknown. Mitochondria, crucial for stress adaptation and energy production, may link psychosocial stress to its biological effects, especially during pregnancy when energy demands significantly increase. This study explores two mitochondrial markers-circulating cell-free mitochondrial DNA (cf-mtDNA) and Growth Differentiation Factor-15 (GDF15)-as potential mitochondrial health indicators linking maternal distress to pregnancy outcomes in two longitudinal studies from the USA and Turkey.

Methods

We analyzed biological, demographic, and psychological data from women in two pregnancy studies: EPI (N=187, USA, Mean age=29.6(SD=6.2) and BABIP (N=198, Turkey, Mean age=32.4(SD=4.0)). Data were collected at multiple time points during the perinatal period, including late 2nd and 3rd trimester, with EPI also including additional data at early 2nd trimester and 4-14 months postpartum. Prenatal maternal psychological distress was measured as perceived stress, anxiety, and depressive symptoms. Plasma cf-mtDNA and GDF15 levels were assessed using qPCR and ELISA, respectively. Statistical analyses included Wilcoxon signed-rank tests, Spearman correlations, and Mann-Whitney tests.

Results

Plasma cf-mtDNA levels did not change significantly during pregnancy in either study. Plasma GDF15 levels increased from early to late pregnancy in both studies and significantly decreased postpartum in EPI. Perinatal maternal distress in the late 2nd and 3rd trimesters was not associated with cf-mtDNA or GDF15 in either study. Metabolic distress, measured as higher pre-pregnancy BMI, was negatively correlated with GDF15 in the late 2nd trimester in EPI and showed a similar trend in BABIP. Similarly, higher maternal psychological distress in the early 2nd trimester were associated with lower cf-mtDNA and a trend for lower GDF15 in EPI. Finally, higher pre-pregnancy BMI and maternal distress in late pregnancy were linked to a smaller decline in GDF15 from late pregnancy to postpartum in EPI, suggesting an interaction between metabolic stress, prenatal distress and post-pregnancy physiological recovery.

Conclusions

This study identified distinct patterns of plasma cf-mtDNA and GDF15 levels during the perinatal period across studies from two countries, revealing unique associations between maternal characteristics, prenatal distress, and pregnancy outcomes, suggesting that maternal distress can interact with energy mobilization during pregnancy.

The researcher's guide to selecting biomarkers in mental health studies

Clinical mental health researchers may understandably struggle with how to incorporate biological assessments in clinical research. The options are numerous and are described in a vast and complex body of literature. Here we provide guidelines to assist mental health researchers seeking to include biological measures in their studies. Apart from a focus on behavioral outcomes as measured via interviews or questionnaires, we advocate for a focus on biological pathways in clinical trials and epidemiological studies that may help clarify pathophysiology and mechanisms of action, delineate biological subgroups of participants, mediate treatment effects, and inform personalized treatment strategies. With this paper we aim to bridge the gap between clinical and biological mental health research by (1) discussing the clinical relevance, measurement reliability, and feasibility of relevant peripheral biomarkers; (2) addressing five types of biological tissues, namely blood, saliva, urine, stool and hair; and (3) providing information on how to control sources of measurement variability.

A platform to map the mind-mitochondria connection and the hallmarks of psychobiology: the MiSBIE study

Health emerges from coordinated psychobiological processes powered by mitochondrial energy transformation. But how do mitochondria regulate the multisystem responses that shape resilience and disease risk across the lifespan? The Mitochondrial Stress, Brain Imaging, and Epigenetics (MiSBIE) study was established to address this question and determine how mitochondria influence the interconnected neuroendocrine, immune, metabolic, cardiovascular, cognitive, and emotional systems among individuals spanning the spectrum of mitochondrial energy transformation capacity, including participants with rare mitochondrial DNA (mtDNA) lesions causing mitochondrial diseases (MitoDs). This interdisciplinary effort is expected to generate new insights into the pathophysiology of MitoDs, provide a foundation to develop novel biomarkers of human health, and integrate our fragmented knowledge of bioenergetic, brain-body, and mind-mitochondria processes relevant to medicine and public health.

Exploring the interplay between stress mediators and skin microbiota in shaping age-related hallmarks: A review

Psychological stress is a major contributing factor to several health problems (e.g., depression, cardiovascular disease). Around 35 % of the world's population suffers from it, including younger generations. Physiologically, stress manifests through neuroendocrine pathways (Hypothalamic-Pituitary-Adrenal (HPA) axis and Sympathetic-Adrenal-Medullary (SAM) system) which culminate in the production of stress mediators like cortisol, epinephrine and norepinephrine. Stress and its mediators have been associated to body aging, through molecular mechanisms such as telomere attrition, mitochondrial dysfunction, cellular senescence, chronic inflammation, and dysbiosis, among others. Regarding its impact in the skin, stress impacts its structural integrity and physiological function. Despite this review focusing on several hallmarks of aging, emphasis was placed on skin microbiota dysbiosis. In this line, several studies, comprising different age groups, demographic contexts and body sites, have reported skin microbiota alterations associated with aging, and some effects of stress mediators on skin microbiota have also been reviewed in this paper. From a different perspective, since it is not a "traditional" stress mediator, oxytocin, a cortisol antagonist, has been related to glucorticoids inhibition and to display positive effects on cellular aging. This hormone dysregulation has been associated to psychological issues such as depression, whereas its upregulation has been linked to positive social interaction.

Psychosocial experiences are associated with human brain mitochondrial biology

Psychosocial experiences affect brain health and aging trajectories, but the molecular pathways underlying these associations remain unclear. Normal brain function relies on energy transformation by mitochondria oxidative phosphorylation (OxPhos). Two main lines of evidence position mitochondria both as targets and drivers of psychosocial experiences. On the one hand, chronic stress exposure and mood states may alter multiple aspects of mitochondrial biology; on the other hand, functional variations in mitochondrial OxPhos capacity may alter social behavior, stress reactivity, and mood. But are psychosocial exposures and subjective experiences linked to mitochondrial biology in the human brain? By combining longitudinal antemortem assessments of psychosocial factors with postmortem brain (dorsolateral prefrontal cortex) proteomics in older adults, we find that higher well-being is linked to greater abundance of the mitochondrial OxPhos machinery, whereas higher negative mood is linked to lower OxPhos protein content. Combined, positive and negative psychosocial factors explained 18 to 25% of the variance in the abundance of OxPhos complex I, the primary biochemical entry point that energizes brain mitochondria. Moreover, interrogating mitochondrial psychobiological associations in specific neuronal and nonneuronal brain cells with single-nucleus RNA sequencing (RNA-seq) revealed strong cell-type-specific associations for positive psychosocial experiences and mitochondria in glia but opposite associations in neurons. As a result, these "mind-mitochondria" associations were masked in bulk RNA-seq, highlighting the likely underestimation of true psychobiological effect sizes in bulk brain tissues. Thus, self-reported psychosocial experiences are linked to human brain mitochondrial phenotypes.

Mitochondrial might: powering the peripartum for risk and resilience

The peripartum period, characterized by dynamic hormonal shifts and physiological adaptations, has been recognized as a potentially vulnerable period for the development of mood disorders such as postpartum depression (PPD). Stress is a well-established risk factor for developing PPD and is known to modulate mitochondrial function. While primarily known for their role in energy production, mitochondria also influence processes such as stress regulation, steroid hormone synthesis, glucocorticoid response, GABA metabolism, and immune modulation - all of which are crucial for healthy pregnancy and relevant to PPD pathology. While mitochondrial function has been implicated in other psychiatric illnesses, its role in peripartum stress and mental health remains largely unexplored, especially in relation to the brain. In this review, we first provide an overview of mitochondrial involvement in processes implicated in peripartum mood disorders, underscoring their potential role in mediating pathology. We then discuss clinical and preclinical studies of mitochondria in the context of peripartum stress and mental health, emphasizing the need for better understanding of this relationship. Finally, we propose mitochondria as biological mediators of resilience to peripartum mood disorders.

Investigating mitochondrial bioenergetics in peripheral blood mononuclear cells of women with childhood maltreatment from post-parturition period to one-year follow-up

BACKGROUND

Childhood maltreatment (CM) exerts various long-lasting psychological and biological changes in affected individuals, with inflammation being an interconnecting element. Besides chronic low-grade inflammation, CM might also affect the energy production of cells by altering the function and density of mitochondria, i.e. the body's main energy suppliers. Here, we compared mitochondrial respiration and density in intact peripheral blood mononuclear cells (PBMC), from women with and without CM between two time points, i.e. at the highly inflammatory phase within 1 week after parturition (t0) and again after 1 year (t2).

METHODS

CM exposure was assessed with the Childhood Trauma Questionnaire. Whole blood was collected from n = 52 healthy women within the study 'My Childhood - Your Childhood' at both time points to isolate and cryopreserve PBMC. Thawed PBMC were used to measure mitochondrial respiration and density by high-resolution respirometry followed by spectrophotometric analyses of citrate-synthase activity.

RESULTS

Over time, quantitative respiratory parameters increased, while qualitative flux control ratios decreased, independently of CM. Women with CM showed higher mitochondrial respiration and density at t0, but not at t2. We found significant CM group × time interaction effects for ATP-turnover-related respiration and mitochondrial density.

CONCLUSIONS

This is the first study to longitudinally investigate mitochondrial bioenergetics in postpartum women with and without CM. Our results indicate that CM-related mitochondrial alterations reflect allostatic load, probably due to higher inflammatory states during parturition, which normalize later. However, later inflammatory states might moderate the vulnerability for a second-hit on the level of mitochondrial bioenergetics, at least in immune cells.

Porcine blood cell and brain tissue energy metabolism: Effects of "early life stress"

Background: Early Life Stress (ELS) may exert long-lasting biological effects, e.g., on PBMC energy metabolism and mitochondrial respiration. Data on its effect on brain tissue mitochondrial respiration is scarce, and it is unclear whether blood cell mitochondrial activity mirrors that of brain tissue. This study investigated blood immune cell and brain tissue mitochondrial respiratory activity in a porcine ELS model. Methods: This prospective randomized, controlled, animal investigation comprised 12 German Large White swine of either sex, which were weaned at PND (postnatal day) 28-35 (control) or PND21 (ELS). At 20-24 weeks, animals were anesthetized, mechanically ventilated and surgically instrumented. We determined serum hormone, cytokine, and "brain injury marker" levels, superoxide anion (O₂ ^•¯) formation and mitochondrial respiration in isolated immune cells and immediate post mortem frontal cortex brain tissue. Results: ELS animals presented with higher glucose levels, lower mean arterial pressure. Most determined serum factors did not differ. In male controls, TNFα and IL-10 levels were both higher than in female controls as well as, no matter the gender in ELS animals. MAP-2, GFAP, and NSE were also higher in male controls than in the other three groups. Neither PBMC routine respiration and brain tissue oxidative phosphorylation nor maximal electron transfer capacity in the uncoupled state (ETC) showed any difference between ELS and controls. There was no significant relation between brain tissue and PBMC, ETC, or brain tissue, ETC, and PBMC bioenergetic health index. Whole blood O₂ ^•¯ concentrations and PBMC O₂ ^•¯ production were comparable between groups. However, granulocyte O₂ ^•¯ production after stimulation with E. coli was lower in the ELS group, and this effect was sex-specific: increased O₂ ^•¯ production increased upon stimulation in all control animals, which was abolished in the female ELS swine. Conclusion: This study provides evidence that ELS i) may, gender-specifically, affect the immune response to general anesthesia as well as O₂ ^•¯ radical production at sexual maturity, ii) has limited effects on brain and peripheral blood immune cell mitochondrial respiratory activity, and iii) mitochondrial respiratory activity of peripheral blood immune cells and brain tissue do not correlate.

The energetic cost of allostasis and allostatic load

Chronic psychosocial stress increases disease risk and mortality, but the underlying mechanisms remain largely unclear. Here we outline an energy-based model for the transduction of chronic stress into disease over time. The energetic model of allostatic load (EMAL) emphasizes the energetic cost of allostasis and allostatic load, where the "load" is the additional energetic burden required to support allostasis and stress-induced energy needs. Living organisms have a limited capacity to consume energy. Overconsumption of energy by allostatic brain-body processes leads to hypermetabolism, defined as excess energy expenditure above the organism's optimum. In turn, hypermetabolism accelerates physiological decline in cells, laboratory animals, and humans, and may drive biological aging. Therefore, we propose that the transition from adaptive allostasis to maladaptive allostatic states, allostatic load, and allostatic overload arises when the added energetic cost of stress competes with longevity-promoting growth, maintenance, and repair. Mechanistically, the energetic restriction of growth, maintenance and repair processes leads to the progressive wear-and-tear of molecular and organ systems. The proposed model makes testable predictions around the physiological, cellular, and sub-cellular energetic mechanisms that transduce chronic stress into disease risk and mortality. We also highlight new avenues to quantify allostatic load and its link to health across the lifespan, via the integration of systemic and cellular energy expenditure measurements together with classic allostatic load biomarkers.

Oxytocin and oxygen: the evolution of a solution to the ‘stress of life’

Oxytocin (OT) and the OT receptor occupy essential roles in our current understanding of mammalian evolution, survival, sociality and reproduction. This narrative review examines the hypothesis that many functions attributed to OT can be traced back to conditions on early Earth, including challenges associated with managing life in the presence of oxygen and other basic elements, including sulfur. OT regulates oxidative stress and inflammation especially through effects on the mitochondria. A related nonapeptide, vasopressin, as well as molecules in the hypothalamic–pituitary–adrenal axis, including the corticotropin-releasing hormone family of molecules, have a broad set of functions that interact with OT. Interactions among these molecules have roles in the causes and consequence of social behaviour and the management of threat, fear and stress. Here, we discuss emerging evidence suggesting that unique properties of the OT system allowed vertebrates, and especially mammals, to manage over-reactivity to the ‘side effects’ of oxygen, including inflammation, oxidation and free radicals, while also supporting high levels of sociality and a perception of safety.

This article is part of the theme issue ‘Interplays between oxytocin and other neuromodulators in shaping complex social behaviours’.

Oxytocin: An Old Hormone, A Novel Psychotropic Drug And Possible Use In Treating Psychiatric Disorders

BACKGROUND

Oxytocin is a nonapeptide synthesized in the paraventricular and supraoptic nuclei of the hypothalamus. Historically, this molecule has been involved as a key factor in the formation of infant attachment, maternal behavior and pair bonding and, more generally, in linking social signals with cognition, behaviors and reward. In the last decades, the whole oxytocin system has gained a growing interest as it was proposed to be implicated in etiopathogenesis of several neurodevelopmental and neuropsychiatric disorders.

METHODS

With the main goal of an in-depth understanding of the oxytocin role in the regulation of different functions and complex behaviors as well as its intriguing implications in different neuropsychiatric disorders, we performed a critical review of the current state of art. We carried out this work through PubMed database up to June 2021 with the search terms: 1) "oxytocin and neuropsychiatric disorders"; 2) "oxytocin and neurodevelopmental disorders"; 3) "oxytocin and anorexia"; 4) "oxytocin and eating disorders"; 5) "oxytocin and obsessive-compulsive disorder"; 6) "oxytocin and schizophrenia"; 7) "oxytocin and depression"; 8) "oxytocin and bipolar disorder"; 9) "oxytocin and psychosis"; 10) "oxytocin and anxiety"; 11) "oxytocin and personality disorder"; 12) "oxytocin and PTSD".

RESULTS

Biological, genetic, and epigenetic studies highlighted quality and quantity modifications in the expression of oxytocin peptide or in oxytocin receptor isoforms. These alterations would seem to be correlated with a higher risk of presenting several neuropsychiatric disorders belonging to different psychopathological spectra. Collaterally, the exogenous oxytocin administration has shown to ameliorate many neuropsychiatric clinical conditions.

CONCLUSION

Finally, we briefly analyzed the potential pharmacological use of oxytocin in patient with severe symptomatic SARS-CoV-2 infection due to its anti-inflammatory, anti-oxidative and immunoregulatory properties.

Emotion regulation moderates between maternal adverse childhood experiences (ACEs) and oxytocin response

Exposure to adverse childhood experiences (ACEs) is associated with oxytocin dysregulation in women, such as decreased peripheral oxytocin concentrations, but little is known about vulnerability markers for oxytocin dysregulation in mothers exposed to ACEs. Identifying vulnerability markers may help inform future targets for prevention and intervention programmes. This study provided a preliminary examination of emotion regulation as a potential moderator of the association between maternal ACEs and peripheral oxytocin levels. The current study included a sample of 38 postpartum women. Women completed questionnaires on exposure to ACEs and difficulties with emotion regulation. At a clinic visit at 9 months postpartum, women provided plasma and salivary oxytocin samples anchored around a mother-infant interaction. Associations between maternal ACEs, three dimensions of difficulties with emotion regulation, and peripheral oxytocin concentrations were examined. Linear regression analyses showed that greater difficulties engaging in goal-directed behaviour (β =  - 0.50, p = 0.01) and more limited access to effective emotion regulation strategies (β =  - 0.68, p < 0.001) were related to reduced plasma oxytocin concentrations in postpartum women. Furthermore, in postpartum women reporting greater exposure to ACEs, higher levels of nonacceptance of emotional responses (β =  - 0.55, p = 0.01) and more limited access to effective emotion regulation strategies (β =  - 0.54, p = 0.01) were associated with reduced salivary oxytocin response (i.e. decreased change in oxytocin concentrations from baseline) following mother-infant interaction. Difficulties with emotion regulation may serve as a vulnerability marker for oxytocin dysregulation in postpartum women exposed to ACEs, and this suggests that emotion regulation may be an important target for future clinical interventions. Future research is recommended which replicates these preliminary results and which examines how emotion regulation and peripheral oxytocin levels in mothers exposed to ACEs are associated with parenting and child development outcomes.

Putative Mental, Physical, and Social Mechanisms of Hormonal Influences on Postpartum Sexuality

Purpose of Review

Much research has documented changes in postpartum sexuality, including changes in sexual functioning and satisfaction for both the birthing parent and their partner(s). These changes are often linked to postpartum changes in hormonal and immune responses, which can have both direct and indirect effects on sexuality.

Recent Findings

Here, we review how postpartum sexuality may be changed via mental, physical, and social/relationship effects of a variety of hormones, including estrogens, progestogens, androgens, cortisol, and oxytocin. We also review the ways in which inflammation may act alongside hormones to influence postpartum sexuality.

Summary

We argue that, as each of these factors strongly influence the action of others, the next phase of research in postpartum sexuality must examine the bidirectional interactions of hormones and their effects on behavior, cognition, and social relationships.

Co-occurrence of preconception maternal childhood adversity and opioid use during pregnancy: Implications for offspring brain development

Understanding of the effects of in utero opioid exposure on neurodevelopment is a priority given the recent dramatic increase in opioid use among pregnant individuals. However, opioid abuse does not occur in isolation-pregnant individuals abusing opioids often have a significant history of adverse experiences in childhood, among other co-occurring factors. Understanding the specific pathways in which these frequently co-occurring factors may interact and cumulatively influence offspring brain development in utero represents a priority for future research in this area. We highlight maternal history of childhood adversity (CA) as one such co-occurring factor that is more prevalent among individuals using opioids during pregnancy and which is increasingly shown to affect offspring neurodevelopment through mechanisms beginning in utero. Despite the high incidence of CA history in pregnant individuals using opioids, we understand very little about the effects of comorbid prenatal opioid exposure and maternal CA history on fetal brain development. Here, we first provide an overview of current knowledge regarding effects of opioid exposure and maternal CA on offspring neurodevelopment that may occur during gestation. We then outline potential mechanistic pathways through which these factors might have interactive and cumulative influences on offspring neurodevelopment as a foundation for future research in this area.

Associations between childhood maltreatment and DNA methylation of the oxytocin receptor gene in immune cells of mother-newborn dyads

The neuropeptide oxytocin (OXT) and its receptor (OXTR) modulate interpersonal relationships, particularly mother-child interactions. DNA methylation (DNAm) changes of the OXTR gene were observed in individuals who experienced Childhood Maltreatment (CM). A modulatory role of single nucleotide polymorphisms (SNP) within OXTR in association with CM on the regulation of OXTR was also postulated. Whether these CM-induced epigenetic alterations are biologically inherited by the offspring remains unknown. We thus investigated possible intergenerational effects of maternal CM exposure on DNAm and OXTR gene expression, additionally accounting for the possible influence of three SNP: rs53576 and rs2254298 (OXTR gene), and rs2740210 (OXT gene). We used the Childhood Trauma Questionnaire to classify mothers into individuals with (CM+) or without CM (CM-). Maternal peripheral immune cells were isolated from venous blood (N = 117) and fetal immune cells from the umbilical cord (N = 113) after parturition. DNA methylation was assessed using MassARRAY. Taqman assays were performed for genotyping and gene expression analyses. Among mothers, CM was not associated with OXTR mean methylation or gene expression. However, four CpG sites showed different methylation levels in CM- compared to CM+. In mothers, the OXTR rs53576 and OXT rs2740210 allelic variations interacted with CM load on the OXTR mean methylation. Maternal and newborns' mean methylation of OXTR were positively associated within CM- dyads, but not in CM+ dyads. We show gene×environment interactions on the epigenetic regulation of the oxytocinergic signaling and show the intergenerational comparability of the OXTR DNAm might be altered in infants of CM+ mothers.

Biological Connection of Psychological Stress and Polytrauma under Intensive Care: The Role of Oxytocin and Hydrogen Sulfide

This paper explored the potential mediating role of hydrogen sulfide (H2S) and the oxytocin (OT) systems in hemorrhagic shock (HS) and/or traumatic brain injury (TBI). Morbidity and mortality after trauma mainly depend on the presence of HS and/or TBI. Rapid "repayment of the O2 debt" and prevention of brain tissue hypoxia are cornerstones of the management of both HS and TBI. Restoring tissue perfusion, however, generates an ischemia/reperfusion (I/R) injury due to the formation of reactive oxygen (ROS) and nitrogen (RNS) species. Moreover, pre-existing-medical-conditions (PEMC's) can aggravate the occurrence and severity of complications after trauma. In addition to the "classic" chronic diseases (of cardiovascular or metabolic origin), there is growing awareness of psychological PEMC's, e.g., early life stress (ELS) increases the predisposition to develop post-traumatic-stress-disorder (PTSD) and trauma patients with TBI show a significantly higher incidence of PTSD than patients without TBI. In fact, ELS is known to contribute to the developmental origins of cardiovascular disease. The neurotransmitter H2S is not only essential for the neuroendocrine stress response, but is also a promising therapeutic target in the prevention of chronic diseases induced by ELS. The neuroendocrine hormone OT has fundamental importance for brain development and social behavior, and, thus, is implicated in resilience or vulnerability to traumatic events. OT and H2S have been shown to interact in physical and psychological trauma and could, thus, be therapeutic targets to mitigate the acute post-traumatic effects of chronic PEMC's. OT and H2S both share anti-inflammatory, anti-oxidant, and vasoactive properties; through the reperfusion injury salvage kinase (RISK) pathway, where their signaling mechanisms converge, they act via the regulation of nitric oxide (NO).

Impact of Glucocorticoid on a Cellular Model of Parkinson's Disease: Oxidative Stress and Mitochondrial Function

Stress seems to contribute to the neuropathology of Parkinson's disease (PD), possibly by dysregulation of the hypothalamic-pituitary-adrenal axis. Oxidative distress and mitochondrial dysfunction are key factors involved in the pathophysiology of PD and neuronal glucocorticoid-induced toxicity. Animal PD models have been generated to study the effects of hormonal stress, but no in vitro model has yet been developed. Our aim was to examine the impact of corticosterone (CORT) administration on a dopaminergic neuronal cell model of PD induced by the neurotoxin MPP⁺, as a new combined PD model based on the marker of endocrine response to stress, CORT, and oxidative-mitochondrial damage. We determined the impact of CORT, MPP⁺ and their co-incubation on reactive oxygen species production (O2^-•), oxidative stress cellular markers (advanced-oxidation protein products and total antioxidant status), mitochondrial function (mitochondrial membrane potential and mitochondrial oxygen consumption rate) and neurodegeneration (Fluoro-Jade staining). Accordingly, the administration of MPP⁺ or CORT individually led to cell damage compared to controls (p < 0.05), as determined by several methods, whereas their co-incubation produced strong cell damage (p < 0.05). The combined model described here could be appropriate for investigating neuropathological hallmarks and for evaluating potential new therapeutic tools for PD patients suffering mild to moderate emotional stress.

Stress and circulating cell-free mitochondrial DNA: A systematic review of human studies, physiological considerations, and technical recommendations

Cell-free mitochondrial DNA (cf-mtDNA) is a marker of inflammatory disease and a predictor of mortality, but little is known about cf-mtDNA in relation to psychobiology. A systematic review of the literature reveals that blood cf-mtDNA varies in response to common real-world stressors including psychopathology, acute psychological stress, and exercise. Moreover, cf-mtDNA is inducible within minutes and exhibits high intra-individual day-to-day variation, highlighting the dynamic regulation of cf-mtDNA levels. We discuss current knowledge on the mechanisms of cf-mtDNA release, its forms of transport ("cell-free" does not mean "membrane-free"), potential physiological functions, putative cellular and neuroendocrine triggers, and factors that may contribute to cf-mtDNA removal from the circulation. A review of in vitro, pre-clinical, and clinical studies shows conflicting results around the dogma that physiological forms of cf-mtDNA are pro-inflammatory, opening the possibility of other physiological functions, including the cell-to-cell transfer of whole mitochondria. Finally, to enhance the reproducibility and biological interpretation of human cf-mtDNA research, we propose guidelines for blood collection, cf-mtDNA isolation, quantification, and reporting standards, which can promote concerted advances by the community. Defining the mechanistic basis for cf-mtDNA signaling is an opportunity to elucidate the role of mitochondria in brain-body interactions and psychopathology.

Mitochondrial bioenergetics in leukocytes and oxidative stress in blood serum of mild to moderately depressed women

Major depressive disorder (MDD) has been associated with lower mitochondrial energy production and higher oxidative stress. We investigated whether these alterations manifest in patients with current mild to moderate MDD severity. We observed no differences in mitochondrial respiration and density (i.e., citrate-synthase activity) in peripheral blood mononuclear cells and oxidative stress markers (i.e., 8-hydroxy-2'-deoxyguanosine, 8-isoprostane) in blood serum of 20 female MDD patients compared to 24 non-depressed women. Alterations in mitochondrial energy production and oxidative stress did not linearly depend on the current severity of MDD. However, biological alterations might rather manifest with higher MDD severity/chronicity and at higher age.

Childhood maltreatment is associated with changes in mitochondrial bioenergetics in maternal, but not in neonatal immune cells

Childhood maltreatment (CM) comprises experiences of abuse and neglect during childhood. CM causes psychological as well as biological alterations in affected individuals. In humans, it is hardly explored whether these CM consequences can be transmitted directly on a biological level to the next generation. Here, we investigated the associations between maternal CM and mitochondrial bioenergetics (mitochondrial respiration and intracellular mitochondrial density) in immune cells of mothers and compared them with those of their newborns. In n = 102 healthy mother-newborn dyads, maternal peripheral blood mononuclear cells and neonatal umbilical cord blood mononuclear cells were collected and cryopreserved shortly after parturition to measure mitochondrial respiration and intracellular mitochondrial density with high-resolution respirometry and spectrophotometric analyses, respectively. Maternal CM was assessed with the Childhood Trauma Questionnaire Maternal and neonatal mitochondrial bioenergetics were quantitatively comparable and positively correlated. Female newborns showed higher mitochondrial respiration compared to male newborns. Maternal CM load was significantly and positively associated with mitochondrial respiration and density in mothers, but not with mitochondrial respiration in newborns. Although maternal and neonatal mitochondrial bioenergetics were positively correlated, maternal CM only had a small effect on mitochondrial density in newborns, which was not significant in this study after adjustment for multiple comparisons. The biological relevance of our finding and its consequences for child development need further investigation in future larger studies. This study reports data on mitochondrial bioenergetics of healthy mother-newborn dyads with varying degrees of CM.

The Role of Oxytocin in Cardiovascular Protection

The beneficial effects of oxytocin on infarct size and functional recovery of the ischemic reperfused heart are well documented. The mechanisms for this cardioprotection are not well defined. Evidence indicates that oxytocin treatment improves cardiac work, reduces apoptosis and inflammation, and increases scar vascularization. Oxytocin-mediated cytoprotection involves the production of cGMP stimulated by local release of atrial natriuretic peptide and synthesis of nitric oxide. Treatment with oxytocin reduces the expression of proinflammatory cytokines and reduces immune cell infiltration. Oxytocin also stimulates differentiation stem cells to cardiomyocyte lineages as well as generation of endothelial and smooth muscle cells, promoting angiogenesis. The beneficial actions of oxytocin may include the increase in glucose uptake by cardiomyocytes, reduction in cardiomyocyte hypertrophy, decrease in oxidative stress, and mitochondrial protection of several cell types. In cardiac and cellular models of ischemia and reperfusion, acute administration of oxytocin at the onset of reperfusion enhances cardiomyocyte viability and function by activating Pi3K and Akt phosphorylation and downstream cellular signaling. Reperfusion injury salvage kinase and signal transducer and activator of transcription proteins cardioprotective pathways are involved. Oxytocin is cardioprotective by reducing the inflammatory response and improving cardiovascular and metabolic function. Because of its pleiotropic nature, this peptide demonstrates a clear potential for the treatment of cardiovascular pathologies. In this review, we discuss the possible cellular mechanisms of action of oxytocin involved in cardioprotection.

Mitochondrial respiratory capacity modulates LPS-induced inflammatory signatures in human blood

Mitochondria modulate inflammatory processes in various model organisms, but it is unclear how much mitochondria regulate immune responses in human blood leukocytes. Here, we examine the effect of i) experimental perturbations of mitochondrial respiratory chain function, and ii) baseline inter-individual variation in leukocyte mitochondrial energy production capacity on stimulated cytokine release and glucocorticoid (GC) sensitivity. In a first cohort, whole blood from 20 healthy women and men was stimulated with increasing concentrations of the immune agonist lipopolysaccharide (LPS). Four inhibitors of mitochondrial respiratory chain Complexes I, III, IV, and V were used (LPS + Mito-Inhibitors) to acutely perturb mitochondrial function, GC sensitivity was quantified using the GC-mimetic dexamethasone (DEX) (LPS + DEX), and the resultant cytokine signatures mapped with a 20-cytokine array. Inhibiting mitochondrial respiration caused large inter-individual differences in LPS-stimulated IL-6 reactivity (Cohen's d = 0.72) and TNF-α (d = 1.55) but only minor alteration in EC50-based LPS sensitivity (d = 0.21). Specifically, inhibiting mitochondrial Complex IV potentiated LPS-induced IL-6 levels by 13%, but inhibited TNF-α induction by 72%, indicating mitochondrial regulation of the IL-6/TNF-α ratio. As expected, DEX treatment suppressed multiple LPS-induced pro-inflammatory cytokines (IFN-γ, IL-6, IL-8, IL-1β, .TNF-α) by >85% and increased the anti-inflammatory cytokine IL-10 by 80%. Inhibiting Complex I potentiated DEX suppression of IL-6 by a further 12% (d = 0.73), indicating partial mitochondrial modulation of glucocorticoid sensitivity. Finally, to examine if intrinsic mitochondrial respiratory capacity may explain a portion of immune reactivity differences across individuals, we measured biochemical respiratory chain enzyme activities and mitochondrial DNA copy number in isolated peripheral blood mononuclear cells (PBMCs) from a second cohort of 44 healthy individuals in parallel with LPS-stimulated IL-6 and TNF-α response. Respiratory chain .function, particularly Complex IV activity, was positively correlated with LPS-stimulated IL-6 levels (r = 0.45, p = 0.002). Overall, these data provide preliminary evidence that mitochondrial behavior modulates LPS-induced inflammatory cytokine signatures in human blood.

What is bipolar disorder? A disease model of dysregulated energy expenditure

Advances in the understanding and management of bipolar disorder (BD) have been slow to emerge. Despite notable recent developments in neurosciences, our conceptualization of the nature of this mental disorder has not meaningfully progressed. One of the key reasons for this scenario is the continuing lack of a comprehensive disease model. Within the increasing complexity of modern research methods, there is a clear need for an overarching theoretical framework, in which findings are assimilated and predictions are generated. In this review and hypothesis article, we propose such a framework, one in which dysregulated energy expenditure is a primary, sufficient cause for BD. Our proposed model is centered on the disruption of the molecular and cellular network regulating energy production and expenditure, as well its potential secondary adaptations and compensatory mechanisms. We also focus on the putative longitudinal progression of this pathological process, considering its most likely periods for onset, such as critical periods that challenges energy homeostasis (e.g. neurodevelopment, social isolation), and the resulting short and long-term phenotypical manifestations.

Pathoetiology and pathophysiology of borderline personality: Role of prenatal factors, gut microbiome, mu- and kappa-opioid receptors in amygdala-PFC interactions

The pathoetiology and pathophysiology of borderline personality disorder (BPD) have been relatively under-explored. Consequently, no targetted pharmaceutical treatments or preventative interventions are available. The current article reviews the available data on the biological underpinnings of BPD, highlighting a role for early developmental processes, including prenatal stress and maternal dysbiosis, in BPD pathoetiology. Such factors are proposed to drive alterations in the infant's gut microbiome, in turn modulating amygdala development and the amygdala's two-way interactions with other brain regions. Alterations in opioidergic activity, including variations in the ratio of the mu-and kappa-opioid receptors seem a significant aspect of BPD pathophysiology, contributing to its comorbidities with depression, anxiety, impulsivity and addiction. Stress and dysphoria are commonly experienced in people classed with BPD. A growing body of data, across a host of medical conditions, indicate that stress and mood dysregulation may be intimately associated with gut dysbiosis and increased gut permeability, coupled to heightened levels of oxidative stress and immune-inflammatory activity. It urgently requires investigation as to the relevance of such gut changes in the course of BPD symptomatology. Accumulating data indicates that BPD symptom exacerbations may be linked to cyclical variations in estrogen, in turn decreasing serotonin and local melatonin synthesis, and thereby overlapping with the pathophysiology of migraine and endometriosis, which also have a heightened association with BPD. Future research directions and treatment implications are indicated.

Early life stress: update on neurophysiologic effects and treatment

PURPOSE OF REVIEW

Recent research on childhood trauma has focused on the effects of in-utero and early life stress (ELS) as well as improving access to care. This review includes the previous year's clinically relevant research with attention to gaps that require further research that should improve patient care.

RECENT FINDINGS

The current article focuses on the latest understanding of ELS effects on the neuroendocrine, inflammatory, immune, and neurologic systems, as well as epigenetic effects with a focus on research examining sex-specific differences. Resilience and innovative treatment delivery models are reviewed with emphasis on integrated care models and technology-based treatments.

SUMMARY

The findings reviewed point toward clinically relevant research avenues. The call for more and better treatment options can only be realized with a better understanding of ELS effects. There is a specific need for more in depth exploration and application of sex-specific differences as well as an examination of the effects of age of onset and chronicity of stressors. New developments in the delivery of interventions and treatment allow the potential to provide broader early access to care.

Accelerating research on biological aging and mental health: Current challenges and future directions

Aging is associated with complex biological changes that can be accelerated, slowed, or even temporarily reversed by biological and non-biological factors. This article focuses on the link between biological aging, psychological stressors, and mental illness. Rather than comprehensively reviewing this rapidly expanding field, we highlight challenges in this area of research and propose potential strategies to accelerate progress in this field. This effort requires the interaction of scientists across disciplines - including biology, psychiatry, psychology, and epidemiology; and across levels of analysis that emphasize different outcome measures - functional capacity, physiological, cellular, and molecular. Dialogues across disciplines and levels of analysis naturally lead to new opportunities for discovery but also to stimulating challenges. Some important challenges consist of 1) establishing the best objective and predictive biological age indicators or combinations of indicators, 2) identifying the basis for inter-individual differences in the rate of biological aging, and 3) examining to what extent interventions can delay, halt or temporarily reverse aging trajectories. Discovering how psychological states influence biological aging, and vice versa, has the potential to create novel and exciting opportunities for healthcare and possibly yield insights into the fundamental mechanisms that drive human aging.

Mitochondrial Psychobiology: Foundations and Applications

Mitochondrial psychobiology is the study of the interactions between psychological states and the biological processes that take place within mitochondria. It also examines how mitochondrial behavior influence neural, endocrine, and immune systems known to transduce psychological experiences into health outcomes. Unlike traditional biological outcomes and mediators, mitochondria are dynamic and multifunctional living organisms. By leveraging a variety of laboratory tools including omics, scientists can now map mitochondrial behavior at multiple levels of complexity - from isolated molecular markers to dynamic functional and signaling outcomes. Here we discuss current efforts to develop relevant measures of mitochondrial behavior in accessible human tissues, increase their biological specificity by applying precise measurements in defined cell populations, create composite indices reflecting mitochondrial health, and integrate these approaches with psycho-neuro-endocrino-immune outcomes. This systematic inter-disciplinary effort will help move the field of mitochondrial psychobiology towards a predictive science explaining how, and to what extent, mitochondria contribute to the biological embedding of stress and other psychological states.

The Association of Childhood Maltreatment With Lipid Peroxidation and DNA Damage in Postpartum Women

Childhood maltreatment (CM) is associated with an increased risk for the development of psychiatric and somatic disorders in later life. A potential link could be oxidative stress, which is defined as the imbalance between the amount of reactive oxygen species (ROS) and the neutralizing capacity of anti-oxidative defense systems. However, the findings linking CM with oxidative stress have been inconsistent so far. In this study, we aimed to further explore this association by investigating biological markers of DNA and lipid damage due to oxidation in a comprehensive approach over two study cohorts of postpartum women (study cohort I and study cohort II). The severity of CM experiences (maltreatment load) was assessed in both studies using the Childhood Trauma Questionnaire. In study cohort I (N = 30), we investigated whether CM was associated with higher levels of structural DNA damage in peripheral blood mononuclear cells (PBMC) by two methods that are highly sensitive for detecting nuclear DNA strand breaks (comet assay and γH2AX staining). In study cohort II (N = 117), we then assessed in a larger cohort, that was specifically controlled for potential confounders for oxidative stress measurements, two established serum and plasma biomarkers of oxidative stress, one representing oxidative DNA and RNA damage (8-hydroxy-2'-deoxyguanosine and 8-hydroxyguanosine; 8-OH(d)G) and the other representing lipid peroxidation (8-isoprostane). In study cohort I, the analyses revealed no significant main effects of maltreatment load on cellular measures of nuclear DNA damage. The analyses of peripheral oxidative stress biomarkers in study cohort II revealed a significant main effect of maltreatment load on free 8-isoprostane plasma levels, but not on total 8-isprostane plasma levels and 8-OH(d)G serum levels. Taken together, by combining different methods and two study cohorts, we found no indications for higher oxidative DNA damages with higher maltreatment load in postpartum women. Further research is needed to investigate whether this increase in free 8-isoprostane is a marker for oxidative stress or whether it is instead functionally involved in ROS-related signaling pathways that potentially regulate inflammatory processes following a history of CM.

The Mitochondrion as Potential Interface in Early-Life Stress Brain Programming

Mitochondria play a central role in cellular energy-generating processes and are master regulators of cell life. They provide the energy necessary to reinstate and sustain homeostasis in response to stress, and to launch energy intensive adaptation programs to ensure an organism’s survival and future well-being. By this means, mitochondria are particularly apt to mediate brain programming by early-life stress (ELS) and to serve at the same time as subcellular substrate in the programming process. With a focus on mitochondria’s integrated role in metabolism, steroidogenesis and oxidative stress, we review current findings on altered mitochondrial function in the brain, the placenta and peripheral blood cells following ELS-dependent programming in rodents and recent insights from humans exposed to early life adversity (ELA). Concluding, we propose a role of the mitochondrion as subcellular intersection point connecting ELS, brain programming and mental well-being, and a role as a potential site for therapeutic interventions in individuals exposed to severe ELS.