The role of inflammation in depression: from evolutionary imperative to modern treatment target

Peripheral mitochondrial DNA as a neuroinflammatory biomarker for major depressive disorder

In the pathogenesis of major depressive disorder, chronic stress-related neuroinflammation hinders favorable prognosis and antidepressant response. Mitochondrial DNA may be an inflammatory trigger, after its release from stress-induced dysfunctional central nervous system mitochondria into peripheral circulation. This evidence supports the potential use of peripheral mitochondrial DNA as a neuroinflammatory biomarker for the diagnosis and treatment of major depressive disorder. Herein, we critically review the neuroinflammation theory in major depressive disorder, providing compelling evidence that mitochondrial DNA release acts as a critical biological substrate, and that it constitutes the neuroinflammatory disease pathway. After its release, mitochondrial DNA can be carried in the exosomes and transported to extracellular spaces in the central nervous system and peripheral circulation. Detectable exosomes render encaged mitochondrial DNA relatively stable. This mitochondrial DNA in peripheral circulation can thus be directly detected in clinical practice. These characteristics illustrate the potential for mitochondrial DNA to serve as an innovative clinical biomarker and molecular treatment target for major depressive disorder. This review also highlights the future potential value of clinical applications combining mitochondrial DNA with a panel of other biomarkers, to improve diagnostic precision in major depressive disorder.

Pharmaceutical-mediated neuroimmune modulation in psychiatric/psychological adverse events

The therapeutic use of many pharmaceuticals, including small molecules and biological therapies, has been associated with the onset of psychiatric and psychological adverse events (PPAEs), posing substantial concerns to patients' health and safety. These events, which encompass mood (e.g., depression, schizophrenia, suicidal ideation) and cognitive changes (e.g., learning and memory impairment, dementia) often remain undetected until advanced stages of clinical trials or pharmacovigilance, mostly because the mechanisms underlying the onset of PPAEs remain poorly understood. In recent years, the role of neuroimmune modulation (comprising an intricate interplay between various cell types and signaling pathways) in PPAEs has garnered substantial interest. Indeed, understanding these complex interactions would substantially contribute to increase the ability to predict the potential onset of PPAEs during preclinical stages of a new drug's R&D. This review provides a comprehensive summary of the most recent advances in neuroimmune modulation-related mechanisms contributing to the onset of PPAEs and their association with specific pharmaceuticals. Reported data strongly support an association between neuroimmune modulation and the onset of PPAEs. Pharmaceuticals may target specific molecular pathways and pathway elements (e.g., cholinergic and serotonergic systems), which in turn may directly or indirectly impact the inflammatory status and the homeostasis of the brain, regulating inflammation and neuronal function. Also, modulation of the peripheral immune system by pharmaceuticals that do not permeate the blood-brain barrier (e.g., monoclonal antibodies) may alter the neuroimmunomodulatory status of the brain, leading to PPAEs. In summary, this review underscores the diverse pathways through which drugs can influence brain inflammation, shedding light on potential targeted interventions.

Inflammation-related abnormal dynamic brain activity correlates with cognitive impairment in first-episode, drug-naïve major depressive disorder

BACKGROUND

Cognitive impairment is common in major depressive disorder (MDD) and potentially linked to inflammation-induced alterations in brain function. However, the relationship between inflammation, dynamic brain activity, and cognitive impairment in MDD remains unclear.

METHODS

Fifty-seven first-episode, drug-naïve MDD patients and sixty healthy controls underwent fMRI scanning. Dynamic amplitude of low-frequency fluctuations (dALFF) and dynamic functional connectivity (dFC) were measured using the sliding window method. Plasma IL - 6 levels and cognitive function were assessed using enzyme-linked immunosorbent assay (ELISA) and the Repeated Battery for Assessment of Neuropsychological Status (RBANS), respectively.

RESULTS

MDD patients exhibited decreased dALFF in the bilateral inferior temporal gyrus (ITG), right inferior frontal gyrus, opercular part (IFGoperc), and bilateral middle occipital gyrus (MOG). Regions of dALFF associated with IL-6 included right ITG (r = -0.400/p = 0.003), left ITG (r = -0.381/p = 0.004), right IFGoperc (r = -0.342/p = 0.011), and right MOG (r = -0.327/p = 0.016). Furthermore, IL-6-related abnormal dALFF (including right ITG: r = 0.309/p = 0.023, left ITG: r = 0.276/p = 0.044) was associated with attention impairment. These associations were absent entirely in MDD patients without suicidal ideation. Additionally, IL-6 levels were correlated with dFC of specific brain regions.

LIMITATIONS

Small sample size and cross-sectional study design.

CONCLUSIONS

Inflammation-related dALFF was associated with attention impairment in MDD patients, with variations observed among MDD subgroups. These findings contribute to the understanding of the intricate relationship between inflammation, dynamic brain activity and cognitive impairments in MDD.

AdipoRon exerts an antidepressant effect by inhibiting NLRP3 inflammasome activation in microglia via promoting mitophagy

Depression is a serious mental disorder that threatens patients' physical and mental health worldwide. The activation of the NLR family pyrin domain-containing 3 (NLRP3) inflammasome is essential for microglia-mediated neuroinflammation and neuronal damage in depression. Numerous pathophysiological factors, such as mitochondrial dysfunction and impaired mitophagy, have an essential role in activating the NLRP3 inflammasome. AdipoRon is a potent adiponectin receptor agonist; however, its antidepressant effects have not been thoroughly investigated. In this study, we found that AdipoRon ameliorated depression-like behavior and neuronal damage induced by chronic unpredictable mild stress (CUMS). Further research demonstrated that AdipoRon inhibited the activation of the NLRP3 inflammasome and protected hippocampal neurons from microglial cytotoxicity by promoting mitophagy, increasing the clearance of damaged mitochondria, and reducing mtROS accumulation. Importantly, inhibition of mitophagy attenuated the antidepressant and neuroprotective effects of AdipoRon. Overall, these findings indicate that AdipoRon alleviates depression by inhibiting NLRP3 inflammasome activation in microglia via improving mitophagy.

C-reactive protein across pregnancy in individuals exposed to childhood maltreatment: The role of psychological and physical sequelae of maltreatment

BACKGROUND

Childhood maltreatment (CM) has long-term consequences for the regulation of stress biology which are particularly pronounced when mental and physical health sequelae have manifested. C-reactive protein (CRP) has been shown to be elevated in the non-pregnant state in association with CM as well as in the setting of CM-associated mental and physical health sequelae. In pregnancy, however, the association between CM and CRP is less clear. We sought to examine this association and consider the moderating role of four common health sequelae of CM (maternal depressive symptoms, overweight/obesity, smoking, and hypertensive disorders during pregnancy).

METHODS

A prospective, longitudinal study of 744 healthy pregnant participants was conducted, with analyses focusing on a sample of 643 participants. CM was assessed with the Childhood Trauma Questionnaire (CTQ) and categorized by whether no vs. one or more moderate to severe CM experiences were reported. Blood serum concentrations of CRP, maternal depression severity (continuous scores of the Center for Epidemiologic Studies Depression Scale, CES-D) and smoking during pregnancy were assessed in early (16.52 ± 2.50 weeks gestation) and late (33.65 ± 1.18 weeks gestation) pregnancy. Pre-pregnancy body mass index (BMI) was obtained at the first study visit and hypertensive disorders diagnosed during pregnancy were obtained from the medical record. Linear mixed effects models were employed to assess main effects of CM as well as interactive effects of CM and four common CM-associated sequelae as well as a sum score of these sequelae on repeatedly measured CRP concentration. In secondary analyses, we conducted latent class analyses to classify participants based on their specific experiences of childhood abuse and/or neglect and to assess the association of these CM subgroups with CM sequelae and CRP. All analyses were adjusted for potential confounders (maternal race and ethnicity and education/income).

RESULTS

CRP concentration decreased from early to late pregnancy (B = -0.06, SE = 0.01, p < 0.001). While there was no main effect of CM on CRP (p = 0.49), the interaction of CM and depressive symptoms was associated with CRP concentration (B = 0.08, SE = 0.04, p < 0.05), indicating higher CRP across pregnancy with increasing levels of depressive symptoms during pregnancy in participants with CM experience. This interaction was mainly driven by participants with co-occurring physical and emotional maltreatment. For none of the other CM-associated sequelae a statistically significant interaction with CM on CRP concentration was observed.

CONCLUSIONS

These results add to the growing empirical evidence suggesting higher inflammation during pregnancy in participants exposed to CM who experience depressive symptoms and highlight the detrimental effects of multiple co-occurring experiences of maltreatment. Given the negative consequences of chronic inflammatory state for the mother and the developing fetus, monitoring and treating psychiatric sequelae during pregnancy among participants exposed to CM is potentially an important opportunity to dampen long-term detrimental effects of CM, serving at least two generations.

Salience network resting state functional connectivity during airway inflammation in asthma: A feature of mental health resilience?

BACKGROUND

Inflammation is an established contributor to the pathophysiology of depression and the prevalence of depression in those with chronic inflammatory disease is two- to four-fold higher than the general population. Yet little is known about the neurobiological changes that confer depression or resilience to depression, that occur when episodes of heightened inflammation are frequent or span many years.

METHODS

We used an innovative combination of longitudinal resting state functional magnetic resonance imaging coupled to segmental bronchial provocation with allergen (SBP-Ag) to assess changes in resting state functional connectivity (rsFC) of the salience network (SN) caused by an acute inflammatory exacerbation in twenty-six adults (15 female) with asthma and varying levels of depressive symptoms. Eosinophils measured in bronchoalveolar lavage fluid and blood provided an index of allergic inflammation and the Beck Depression Inventory provided an index of depressive symptoms.

RESULTS

We found that in those with the highest symptoms of depression at baseline, SN rsFC declined most from pre- to post-SBP-Ag in the context of a robust eosinophilic response to challenge, but in those with low depressive symptoms SN rsFC was maintained or increased, even in those with the most pronounced SBP-Ag response.

CONCLUSIONS

Thus, the maintenance of SN rsFC during inflammation may be a biomarker of resilience to depression, perhaps via more effective orchestration of large-scale brain network dynamics by the SN. These findings advance our understanding of the functional role of the SN during inflammation and inform treatment recommendations for those with comorbid inflammatory disease and depression.

Higher inflammatory proteins predict future depressive symptom severity among adolescents with lower emotional clarity

BACKGROUND

A growing body of work has implicated inflammation in the pathogenesis of depression. As not all individuals with heightened levels of peripheral inflammation develop symptoms of depression, additional work is needed to identify other factors that catalyze the relationship between inflammation and depressive symptoms. Given that elevated levels of inflammatory activity can induce a variety of emotional changes, the present study examined whether emotional clarity, the trait-like ability to identify, discern, and express one's emotions, influences the strength of the association between inflammatory signaling and concurrent and prospective symptoms of depression.

METHODS

Community adolescents (N = 225, Mage = 16.63 years), drawn from a larger longitudinal project investigating sex and racial differences in depression onset, provided blood samples to determine peripheral levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and C-reactive protein (CRP) at a baseline visit, along with self-report measures of emotional clarity and depressive symptom severity. Depressive symptom severity was assessed again at a follow-up visit approximately 5-months after baseline.

RESULTS

Hierarchical multiple regressions detected a significant interaction between inflammatory markers and emotional clarity on future depression severity, controlling for baseline depressive symptoms. Specifically, among adolescents with low levels of emotional clarity, higher levels of IL-6, CRP, and inflammatory composite scores were significantly associated with greater future depression severity.

CONCLUSIONS

These results indicate that low emotional clarity and high inflammatory signaling may jointly confer risk for prospective depressive symptom severity among adolescents. Therapeutic interventions that improve emotional clarity may reduce risk of depressive symptoms among adolescents with low-grade peripheral inflammation.

Biomarkers as predictors of CBT responsiveness in major depressive disorder: The role of heart rate variability and inflammation

OBJECTIVE

Biological risk factors for cardiovascular disease may relate to poor treatment responsiveness in major depressive disorder (MDD). These factors encompass low-grade inflammation and autonomic dysregulation, as indexed by decreased heart rate variability (HRV) and increased heart rate (HR). This secondary analysis examined whether higher levels of inflammatory markers or autonomic alterations relate to lower responsiveness to cognitive behavioral therapy (CBT) among individuals with MDD.

METHODS

Eighty antidepressant-free patients with MDD were randomly assigned to 14 weeks of CBT or waitlist (WL). Potential biological moderators at study entry included HR and HRV (24-h, daytime, nighttime) and inflammatory markers such as C-reactive protein (CRP), interleukin (IL)-6, and tumor necrosis factor (TNF)-α. Forty non-clinical controls were involved to verify biological alterations in MDD at study entry. Depressive symptoms were assessed at baseline and at the end of treatment.

RESULTS

Individuals with MDD exhibited reduced total 24-h HRV (i.e., triangular index) and daytime HRV (i.e., triangular index, HF-HRV, LF-HRV, RMSSD), as well as increased levels of inflammatory markers. Patients who received CBT exhibited stronger reductions in self- and clinician-rated depressive symptoms, compared to WL. False discovery rate-adjusted moderation analyses did not show overall moderating effects of biological measures on treatment responsiveness. However, higher CRP levels were specifically associated with poorer improvement in somatic depressive symptoms.

CONCLUSIONS

There was no overall evidence for a moderating role of inflammation or autonomic features in CBT responsiveness in MDD. Higher levels of CRP might, however, specifically be associated with less improvement in somatic depressive symptoms during CBT.

Immunological correlates of suicidality among adolescents with internalizing symptoms

Background

Suicide is a leading cause of death in adolescents and young adults globally. Well-established risk factors for suicide are depression and past suicide attempts. People experiencing suicidality may represent a distinct neurobiological group of people with depression. Because converging evidence has implicated inflammation in depression, we sought to investigate relationships between suicidality and immune markers in youth experiencing diverse mood and anxiety symptoms. We hypothesized that adolescents with suicidality would exhibit a unique immune signature.

Methods

Adolescents underwent semi-structured interviews and completed self-reported measures to assess psychopathology, including suicidality (suicidal ideation, plans, or attempts). Fasting blood samples were collected, cultured with and without lipopolysaccharide (LPS) to stimulate an inflammatory response, and analyzed for 41 immune analytes. To assess how immune function related to suicidality categorically and dimensionally, we conducted group comparisons and correlations while controlling for multiple comparisons using false discovery rate (FDR). To further uncover subtle immune-suicidality relationships, we employed a data-driven approach using factor analysis to extract major immune factors, each of which was subsequently correlated with suicidality measures.

Results

Among 126 participants, 29 were healthy controls and 97 participants had internalizing symptoms; within the clinical group, 57 experienced suicidality. Three immune analytes differed between healthy controls, suicidal, and non-suicidal adolescents with internalizing symptoms in the LPS condition: Flt-3L (p FDR = 0.0246), GM-CSF (p FDR = 0.0246), and IFN-γ (p FDR = 0.0246). These analytes were negatively correlated with the Beck Scale for Suicide Ideation (BSSI): Flt-3L (ρ = -0.19, p = 0.04); GM-CSF (ρ = -0.26, p = 0.004); IFN-γ (ρ =-0.33, p = 0.0003). GM-CSF also negatively correlated with number of suicide attempts (ρ = -0.39, p = 0.003). Factor analysis reduced 41 analytes to several common immune factors across experimental conditions, with Flt-3L, GM-CSF, and IFN-γ all loading heavily onto immune factors that were hypoactive in suicidality. Through this data-driven approach, we detected further associations between suicidality and immune factors across all conditions.

Conclusions

Peripheral immune function may be distinctly altered in adolescent suicidality. Future work should examine immune-suicidality relationships longitudinally.

Innate immunity-mediated neuroinflammation promotes the onset and progression of post-stroke depression

Post-stroke depression (PSD) is a prevalent psychiatric disorder after stroke, with the incidence of approximately one-third among stroke survivors. It is classified as an organic mental disorder and has a well-documented association with stroke affecting various aspects of patients, such as the recovery of limb motor function, daily living self-care ability, and increasing the mortality of stroke survivors. However, the pathogenesis of PSD is not yet fully understood. Currently, immune inflammation is a research hotspot. This review focuses on the pathogenesis of PSD, particularly elucidating the role of inflammation in mediating neuroinflammation through innate immunity. Simultaneously, we highlight that peripheral inflammation following a stroke may trigger a detrimental cycle of neuroinflammation by activating innate immune pathways within the central nervous system, which could potentially contribute to the development of PSD. Lastly, we summarize potential treatments for PSD and propose targeting cytokines and innate immune pathways as novel therapeutic approaches.

Agmatine modulation of gut-brain axis alleviates dysbiosis-induced depression-like behavior in rats

Depression is a global health concern affecting nearly 280 million individuals. It not only imposes a significant burden on economies and healthcare systems but also manifests complex physiological connections and consequences. Agmatine, a putative neuromodulator derived primarily from beneficial gut microbes specially Lactobacillus, has emerged as a potential therapeutic agent for mental health. The microbiota-gut-brain axis is involved in the development of depression through the peripheral nervous system, endocrine system, and immune system and may be a key factor in the effect of agmatine. Therefore, this study aimed to investigate the potential mechanism of agmatine in antibiotic-induced dysbiosis and depression-like behavior in rats, focusing on its modulation of the gut-brain axis. Depression-like behavior associated with dysbiosis was induced through a seven-day regimen of the broad-spectrum antibiotic, comprising ampicillin and metronidazole and validated through microbial, biochemical, and behavioral alterations. On day 8, antibiotic-treated rats exhibited loose fecal consistency, altered fecal microbiota, and depression-like behavior in forced swim test. Pro-inflammatory cytokines were elevated, while agmatine and monoamine levels decreased in the hippocampus and prefrontal cortex. Antibiotic administration disrupted tight junction proteins in the ileum, affecting gut architecture. Oral administration of agmatine alone or combined with probiotics significantly reversed antibiotic-induced dysbiosis, restoring gut microbiota and mitigating depression-like behaviors. This intervention also restored neuro-inflammatory markers, increased agmatine and monoamine levels, and preserved gut integrity. The study highlights the regulatory role of endogenous agmatine in the gut-brain axis in broad-spectrum antibiotic induced dysbiosis and associated depression-like behavior.

Biological rhythms in premenstrual syndrome and premenstrual dysphoric disorder: a systematic review

BACKGROUND

Women with premenstrual syndrome (PMS) and premenstrual dysphoric disorder (PMDD) typically experience a range of psychological and physiological symptoms that negatively affect their quality of life. Disruption in biological rhythms, including alterations of the sleep-wake cycle, have been implicated in PMS/PMDD, though literature is still growing to substantiate these findings. The objective of this study is to systematically review the available literature on biological rhythms disruption in PMS/PMDD.

METHODS

A literature search was conducted on four databases (Pubmed, Embase, Medline, and Web of Science) on December 3rd, 2021. This search yielded a total of 575 articles that assessed the relationship between biological rhythms and PMS/PMDD/premenstrual symptoms.

RESULTS

After the exclusion of irrelevant articles and hand-searching references, 25 articles were included in this systematic review. Some studies showed that women with PMS/PMDD present lower melatonin levels, elevated nighttime core body temperature, and worse subjective perception of sleep quality when compared to women without PMS/PMDD. Other biological rhythms parameters showed either no differences between groups (wrist actimetry) or conflicting results (objective sleep parameters, cortisol, prolactin, and thyroid stimulating hormone).

CONCLUSION

Current research demonstrates that women with PMS/PMDD experience lower melatonin levels, higher body temperature, and worse subjective perception of sleep quality. This review outlines some possible mechanisms behind these findings and proposes recommendations for future research. This systematic review was registered in the International Prospective Register of Systematic Reviews (PROSPERO) under registration number CRD42020149921.

CUMS induces depressive-like behaviors and cognition impairment by activating the ERS-NLRP3 signaling pathway in mice

BACKGROUND AND OBJECTIVE

Endoplasmic reticulum stress (ERS), as a primary defense mechanism against stress, is closely related to mental disorders, but its pathogenesis is still unclear. This research seeks to explore the influence of ERS-nucleotide-bound oligomerized domain-like receptor protein 3 (NLRP3) signaling on mice's depressive-like behaviors and cognitive impairment.

DESIGN AND METHOD

We carried out a study on 32 male C57BL/6J mice to investigate how chronic unpredictable mild stress (CUMS) can give rise to depressive-like behaviors and cognitive dysfunction, randomly dividing them into control, model, inhibitor, and agonist groups. We utilized ELISA to quantify dopamine (DA) and 5-hydroxytryptamine (5-HT) levels. Using Nissl and hematoxylin and eosin (H&E) staining, we assessed the number and morphology of hippocampal neurons and cells. Western blot and immunofluorescence staining detected the changes in ERS and inflammation-related pathways in the hippocampus.

RESULTS

CUMS could induce ERS and activate NLRP3 inflammasome, causing neuronal damage and histopathological changes, eventually leading to depressive-like behaviors and cognitive impairment in mice. The abnormal activation of NLRP3 inflammasome could be restored by ERS blocker 4-phenyl butyric acid (PBA), thus reducing neuronal damage, and ameliorating depressive-like behaviors and cognitive disorder in mice.

CONCLUSION

Our study demonstrates a previously unknown link between ERS and NLRP3 inflammasome in CUMS mice. The ERS-NLRP3 signaling pathway may be activated by CUMS, potentially resulting in mice exhibiting depressive-like behaviors and cognitive dysfunction. Theoretical foundations for elucidating the pathogenesis of depression, as well as its prevention and treatment, will be established through the results.

Acupuncture may play a key role in anti-depression through various mechanisms in depression

Depression has emerged as a significant global health concern, exerting a profound impact on individuals, as evidenced by its high prevalence and associated suicide rates. Considering its pervasive nature, the absence of optimal treatment modalities remains a challenge. Acupuncture has garnered substantial clinical and experimental validation for its efficacy in addressing diverse forms of depression, including postpartum, post-stroke, and adolescent depression. This article endeavors to elucidate the distinctive attributes and underlying mechanisms of acupuncture in the contemporary treatment of depression. Research has demonstrated that acupuncture exerts diverse physiological effects in animal models of depression, encompassing modulation of the brain, serum, and brain-gut axis. These effects are attributed to various mechanisms, including anti-inflammatory and anti-oxidative actions, promotion of neuronal plasticity, neuroprotection, neurotrophic effects, modulation of neurotransmitters, regulation of endocrine and immune functions, and modulation of cell signal pathways. Currently, the therapeutic mechanism of acupuncture involves the engagement of multiple targets, pathways, and bidirectional regulation. Hence, acupuncture emerges as a promising alternative medical modality, exhibiting substantial research prospects and meriting comprehensive worth further study and dissemination.

Sex differences in the inflammation-depression link: A systematic review and meta-analysis

Major Depressive Disorder (MDD) is a heterogeneous disorder that affects twice as many women than men. Precluding advances in more tailored and efficacious treatments for depression is the lack of reliable biomarkers. While depression is linked to elevations in inflammatory immune system functioning, this relationship is not evident among all individuals with depression and may vary based on symptom subtypes and/or sex. This systematic review and meta-analysis examined whether inflammatory immune peripheral markers of depression are sex-specific. PRISMA guidelines were followed for the systematic review, and a comprehensive search strategy that identified studies from PubMed and PsycInfo was applied. Studies were included if they reported C-reactive protein (CRP), interleukin (IL)-6, tumor necrosis factor (TNF)-α and/or IL-1β for males and/or females among depressed and healthy adults. We identified 23 studies that satisfied these inclusion criteria. Random-effects meta-analysis models were fit, and measures of association were summarized between levels of circulating markers of inflammation in depressed and healthy males and females. Sex-based analyses revealed elevated levels of CRP among females with depression (Cohen's d = 0.19) relative to their healthy counterparts (p = 0.02), an effect not apparent among males (Cohen's d = -0.01). Similarly, levels of IL-6 were increased among females with depression compared to healthy controls (Cohen's d = 0.51; p = 0.04), but once again this was not found among males (Cohen's d = 0.16). While TNF-α levels were elevated among individuals with depression compared to controls (p = 0.01), no statistically significant sex differences were found. The meta-analysis for IL-1β resulted in only three articles, and thus, results are presented in the supplemental section. This meta-analysis advances our understanding of the unique involvement of inflammatory biomarkers in depression among men and women, which may help inform more tailored sex-specific treatment approaches in the future.

The Role of Inflammation in Depression and Beyond: A Primer for Clinicians

PURPOSE OF REVIEW

We evaluate available evidence for the role of inflammation in depression. We reappraise literature involving systemic inflammation, neuroinflammation and neurotransmission and their association with depression. We review the connection between depression, autoimmunity and infectious diseases. We revise anti-inflammatory treatments used in depression.

RECENT FINDINGS

Peripheral inflammatory markers are present in a subset of patients with depression and can alter common neurotransmitters in this population but there is no clear causality between depression and systemic inflammation. Infectious conditions and autoimmune illnesses do not have a clear correlation with depression. Certain medications have positive evidence as adjunctive treatments in depression but studies are heterogenic, hence they are sparsely used in clinical settings. The current evidence does not fully support inflammation, infections or autoimmunity as possible etiologies of depression. The available studies have numerous confounders that obscure the findings. Anti-inflammatory agents may have potential for treatment of depression, but further research is needed to clarify their usefulness in routine clinical practice.

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.

Inulae Flos has Anti-Depressive Effects by Suppressing Neuroinflammation and Recovering Dysfunction of HPA-axis

Depression is a debilitating mood disorder that causes persistent feelings of sadness, emptiness, and a loss of joy. However, the clinical efficacy of representative drugs for depression, such as selective serotonin reuptake inhibitors, remains controversial. Therefore, there is an urgent need for more effective therapies to treat depression. Neuroinflammation and the hypothalamic-pituitary-adrenal (HPA) axis are pivotal factors in depression. Inulae Flos (IF), the flower of Inula japonica Thunb, is known for its antioxidant and anti-inflammatory effects. This study explored whether IF alleviates depression in both in vitro and in vivo models. For in vitro studies, we treated BV2 and PC12 cells damaged by lipopolysaccharides or corticosterone (CORT) with IF to investigate the mechanisms of depression. For in vivo studies, C57BL/6 mice were exposed to chronic restraint stress and were administered IF at doses of 0, 100, and 300 mg/kg for 2 weeks. IF inhibited pro-inflammatory mediators, such as nitric oxide, inducible nitric oxide synthase, and interleukins in BV2 cells. Moreover, IF increased the viability of CORT-damaged PC12 cells by modulating protein kinase B, a mammalian target of the rapamycin pathway. Behavioral assessments demonstrated that IF reduced depression-like behaviors in mice. We found that IF reduced the activation of microglia and astrocytes, and regulated synapse plasticity in the mice brains. Furthermore, IF lowered elevated CORT levels in the plasma and restored glucocorticoid receptor expression in the hypothalamus. Collectively, these findings suggest that IF can alleviate depression by mitigating neuroinflammation and recovering dysfunction of the HPA-axis.

Well-Being and Cardiovascular Health: Insights From the UK Biobank Study

BACKGROUND

Cardiovascular diseases (CVDs) are a leading global health concern. Emerging evidence suggests a potential protective role of well-being in reducing CVD risk.

METHODS AND RESULTS

We conducted a cohort analysis using the UK Biobank data set, encompassing 121 317 participants. We assessed the well-being of participants using a well-being index derived from baseline questionnaires. Well-being categories were derived by latent class analysis using general happiness and satisfaction with family, friendships, health, and finance situations. The relationship between well-being and 4 major CVDs was analyzed using Cox proportional hazards models and Mendelian randomization. The study also examined the impacts of well-being on lifestyle factors and inflammatory markers, and its mediating role in the well-being-CVD relationship. Higher well-being was associated with a significantly reduced risk of various CVDs. Latent class analysis identified 4 distinct well-being groups (low, variable, moderate-to-high, and high satisfaction), with higher satisfaction levels generally associated with lower risk of CVDs. Mendelian randomization suggested potential causal relationships between well-being and reduced risk of CVDs. Participants with greater well-being demonstrated healthier behaviors and lower levels of inflammatory markers. Mediation analysis indicated that lifestyle and inflammatory markers partially mediated the relationship between well-being and CVDs.

CONCLUSIONS

This study demonstrates a robust inverse association between well-being and the risks of CVDs, suggesting that enhancing well-being may be a viable strategy for CVD prevention. The role of lifestyle factors and inflammation as a mediator provides insight into possible biological pathways linking psychological states and cardiovascular health.

The interplay between polygenic score for tumor necrosis factor-α, brain structural connectivity, and processing speed in major depression

Reduced processing speed is a core deficit in major depressive disorder (MDD) and has been linked to altered structural brain network connectivity. Ample evidence highlights the involvement of genetic-immunological processes in MDD and specific depressive symptoms. Here, we extended these findings by examining associations between polygenic scores for tumor necrosis factor-α blood levels (TNF-α PGS), structural brain connectivity, and processing speed in a large sample of MDD patients. Processing speed performance of n = 284 acutely depressed, n = 177 partially and n = 198 fully remitted patients, and n = 743 healthy controls (HC) was estimated based on five neuropsychological tests. Network-based statistic was used to identify a brain network associated with processing speed. We employed general linear models to examine the association between TNF-α PGS and processing speed. We investigated whether network connectivity mediates the association between TNF-α PGS and processing speed. We identified a structural network positively associated with processing speed in the whole sample. We observed a significant negative association between TNF-α PGS and processing speed in acutely depressed patients, whereas no association was found in remitted patients and HC. The mediation analysis revealed that brain connectivity partially mediated the association between TNF-α PGS and processing speed in acute MDD. The present study provides evidence that TNF-α PGS is associated with decreased processing speed exclusively in patients with acute depression. This association was partially mediated by structural brain connectivity. Using multimodal data, the current findings advance our understanding of cognitive dysfunction in MDD and highlight the involvement of genetic-immunological processes in its pathomechanisms.

Immunity impacts cognitive deficits across neurological disorders

Cognitive deficits are a common comorbidity with neurological disorders and normal aging. Inflammation is associated with multiple diseases including classical neurodegenerative dementias such as Alzheimer's disease (AD) and autoimmune disorders such as multiple sclerosis (MS), in which over half of all patients experience some form of cognitive deficits. Other degenerative diseases of the central nervous system (CNS) including frontotemporal lobe dementia (FTLD), and Parkinson's disease (PD) as well as traumatic brain injury (TBI) and psychological disorders like major depressive disorder (MDD), and even normal aging all have cytokine-associated reductions in cognitive function. Thus, there is likely commonality between these secondary cognitive deficits and inflammation. Neurological disorders are increasingly associated with substantial neuroinflammation, in which CNS-resident cells secrete cytokines and chemokines such as tumor necrosis factor (TNF)α and interleukins (ILs) including IL-1β and IL-6. CNS-resident cells also respond to a wide variety of cytokines and chemokines, which can have both direct effects on neurons by changing the expression of ion channels and perturbing electrical properties, as well as indirect effects through glia-glia and immune-glia cross-talk. There is significant overlap in these cytokine and chemokine expression profiles across diseases, with TNFα and IL-6 strongly associated with cognitive deficits in multiple disorders. Here, we review the involvement of various cytokines and chemokines in AD, MS, FTLD, PD, TBI, MDD, and normal aging in the absence of dementia. We propose that the neuropsychiatric phenotypes observed in these disorders may be at least partially attributable to a dysregulation of immunity resulting in pathological cytokine and chemokine expression from both CNS-resident and non-resident cells.

Balancing the mind: Toward a complete picture of the interplay between gut microbiota, inflammation and major depressive disorder

The intricate interplay existing between gut microbiota and homeostasis extends to the realm of the brain, where emerging research underscores the significant impact of the microbiota on mood regulation and overall neurological well-being and vice-versa, with inflammation playing a pivotal role in mediating these complex interactions. This comprehensive review explores the complex interplay between inflammation, alterations in gut microbiota, and their impact on major depressive disorder (MDD). It provides a cohesive framework for the puzzle pieces of this triad, emphasizing recent advancements in understanding the gut microbiota and inflammatory states' contribution to the depressive features. Two directions of communication between the gut and the brain in depression are discussed, with inflammation serving as a potential modulator. Therapeutic implications were discussed as well, drawing insights from interventional studies on the effects of probiotics on gut bacterial composition and depressive symptoms. Ultimately, this review will attempt to provide a complete and valuable framework for future research and therapeutic interventions in MDD.

Splenic nerve denervation attenuates depression-like behaviors in Chrna7 knock-out mice via the spleen-gut-brain axis

BACKGROUND

Growing evidence highlights the role of the spleen-brain axis in inflammation-associated depression. The α7-subtype of nicotinic acetylcholine receptor (α7 nAChR, encoded by the Chrna7 gene) is implicated in systemic inflammation, with Chrna7 knock-out (KO) mice displaying depression-like behaviors. Yet, the influence of spleen nerve on depression-like behaviors in these KO mice remains to be elucidated.

METHODS

We investigated the effects of the splenic nerve denervation (SND) on depression-like behaviors, the protein expression in the prefrontal cortex (PFC), and the gut microbiota composition in Chrna7 KO mice.

RESULTS

SND markedly alleviated depression-like behaviors and the reduced expression of GluA1 and postsynaptic density protein-95 (PSD-95) in the PFC of Chrna7 KO mice. No changes in α-diversity of gut microbiota were noted among the control, KO + sham, and KO + SND groups. However, significant differences in β-diversity of gut microbiota were noted among the groups. Notable alterations in various microbiota (e.g., Fluviimonas_pallidilutea, Maribacter_arcticus, Parvibacter_caecicola) and plasma metabolites (e.g., helicide, N-acetyl-L-aspartic acid, α-D-galactose 1-phosphate, choline, creatine) were observed between KO + sham and KO + SND groups. Interestingly, correlations were found between the relative abundance of specific microbiota and other outcomes, including synaptic proteins, metabolites and behavioral data.

LIMITATIONS

The underlying mechanisms remain to be fully understood.

CONCLUSIONS

Our findings indicate that the splenic nerve contributes to depression-like phenotypes in Chrna7 KO mice via the spleen-gut-brain axis.

PET imaging assist investigation of HDAC6 expression change in MDD and evaluating antidepressant efficacy of a newly developed HDAC6 inhibitor

The histone deacetylase 6 (HDAC6) is closely related to the pathogenesis of depression in epigenetic regulation. However, it remains unclear how HDAC6 expression changes in depression pathophysiology and whether it is a target for antidepressant treatment. Herein, we investigate the expression change of HDAC6 in major depressive disorder (MDD) and evaluate the efficacy of a novel HDAC6 inhibitor, PB200, using positron emission tomography (PET) imaging. PET imaging studies with an HDAC6 PET probe [18F]Bavarostat allied with in vitro experiments demonstrated significantly increased HDAC6 expression in the brains of MDD mice. To investigate if pharmacological inhibition of HDAC6 can exert antidepressant effects, a series of naphthyridine-based HDAC6 inhibitors were designed and synthesized, among which PB200 demonstrated high selectivity and inhibitory activity against HDAC6, favorable metabolic stability, and excellent brain uptake. Moreover, PB200 exhibited significant antidepressant effects by restoring abnormal HDAC6 expression level and alleviating neuroinflammation. These results imply that targeting HDAC6 shows promise as a therapeutic strategy for depression, and PB200 is a potential therapeutic option for treating MDD.

Nine Neuroimaging-AI Endophenotypes Unravel Disease Heterogeneity and Partial Overlap across Four Brain Disorders: A Dimensional Neuroanatomical Representation

Disease heterogeneity poses a significant challenge for precision diagnostics. Recent work leveraging artificial intelligence has offered promise to dissect this heterogeneity by identifying complex intermediate brain phenotypes, herein called dimensional neuroimaging endophenotypes (DNEs). We advance the argument that these DNEs capture the degree of expression of respective neuroanatomical patterns measured, offering a dimensional neuroanatomical representation for studying disease heterogeneity and similarities of neurologic and neuropsychiatric diseases. We investigate the presence of nine such DNEs derived from independent yet harmonized studies on Alzheimer's disease (AD1-2) 1 , autism spectrum disorder (ASD1-3) 2 , late-life depression (LLD1-2) 3 , and schizophrenia (SCZ1-2) 4 , in the general population of 39,178 participants in the UK Biobank study. Phenome-wide associations revealed prominent associations between the nine DNEs and phenotypes related to the brain and other human organ systems. This phenotypic landscape aligns with the SNP-phenotype genome-wide associations, revealing 31 genomic loci associated with the nine DNEs (Bonferroni corrected P- value < 5x10 -8 /9). The DNEs exhibited significant genetic correlations, colocalization, and causal relationships with multiple human organ systems and chronic diseases. A causal effect (odds ratio=1.25 [1.11, 1.40], P-value=8.72x10 -4 ) was established from AD2, characterized by focal medial temporal lobe atrophy, to AD. The nine DNEs, along with their polygenic risk scores, significantly enhanced the predictive accuracy for 14 systemic disease categories, particularly for conditions related to mental health and the central nervous system, as well as mortality outcomes. These findings underscore the potential of the nine DNEs to capture the expression of disease-related brain phenotypes in individuals of the general population and to relate such measures with genetics, lifestyle factors, and chronic diseases. All results are publicly available at https://labs-laboratory.com/medicine/ .

Overexpression of the schizophrenia risk gene C4 in PV cells drives sex-dependent behavioral deficits and circuit dysfunction

Fast-spiking parvalbumin (PV)-positive cells are key players in orchestrating pyramidal neuron activity, and their dysfunction is consistently observed in myriad brain diseases. To understand how immune complement pathway dysregulation in PV cells drives disease pathogenesis, we have developed a transgenic line that permits cell-type specific overexpression of the schizophrenia-associated C4 gene. We found that overexpression of mouse C4 (mC4) in PV cells causes sex-specific alterations in anxiety-like behavior and deficits in synaptic connectivity and excitability of PFC PV cells. Using a computational model, we demonstrated that these microcircuit deficits led to hyperactivity and disrupted neural communication. Finally, pan-neuronal overexpression of mC4 failed to evoke the same deficits in behavior as PV-specific mC4 overexpression, suggesting that perturbations of this neuroimmune gene in fast-spiking neurons are especially detrimental to circuits associated with anxiety-like behavior. Together, these results provide a causative link between C4 and the vulnerability of PV cells in brain disease.

Dissecting depression symptoms: Multi-omics clustering uncovers immune-related subgroups and cell-type specific dysregulation

In a subset of patients with mental disorders, such as depression, low-grade inflammation and altered immune marker concentrations are observed. However, these immune alterations are often assessed by only one data type and small marker panels. Here, we used a transdiagnostic approach and combined data from two cohorts to define subgroups of depression symptoms across the diagnostic spectrum through a large-scale multi-omics clustering approach in 237 individuals. The method incorporated age, body mass index (BMI), 43 plasma immune markers and RNA-seq data from peripheral mononuclear blood cells (PBMCs). Our initial clustering revealed four clusters, including two immune-related depression symptom clusters characterized by elevated BMI, higher depression severity and elevated levels of immune markers such as interleukin-1 receptor antagonist (IL-1RA), C-reactive protein (CRP) and C-C motif chemokine 2 (CCL2 or MCP-1). In contrast, the RNA-seq data mostly differentiated a cluster with low depression severity, enriched in brain related gene sets. This cluster was also distinguished by electrocardiography data, while structural imaging data revealed differences in ventricle volumes across the clusters. Incorporating predicted cell type proportions into the clustering resulted in three clusters, with one showing elevated immune marker concentrations. The cell type proportion and genes related to cell types were most pronounced in an intermediate depression symptoms cluster, suggesting that RNA-seq and immune markers measure different aspects of immune dysregulation. Lastly, we found a dysregulation of the SERPINF1/VEGF-A pathway that was specific to dendritic cells by integrating immune marker and RNA-seq data. This shows the advantages of combining different data modalities and highlights possible markers for further stratification research of depression symptoms.

A randomized proof-of-mechanism trial of TNF antagonism for motivational deficits and related corticostriatal circuitry in depressed patients with high inflammation

Chronic, low-grade inflammation has been associated with motivational deficits in patients with major depression (MD). In turn, impaired motivation has been linked to poor quality of life across psychiatric disorders. We thus determined effects of the anti-inflammatory drug infliximab-a potent tumor necrosis factor (TNF) antagonist-on behavioral and neural measures of motivation in 42 medically stable, unmedicated MD patients with a C-reactive protein >3 mg/L. All patients underwent a double-blind, placebo-controlled, single-dose, randomized clinical trial with infliximab (5 mg/kg) versus placebo. Behavioral performance on an effort-based decision-making task, self-report questionnaires, and neural responses during event-related functional magnetic resonance imaging were assessed at baseline and 2 weeks following infusion. We found that relative to placebo, patients receiving infliximab were more willing to expend effort for rewards. Moreover, increase in effortful choices was associated with reduced TNF signaling as indexed by decreased soluble TNF receptor type 2 (sTNFR2). Changes in effort-based decision-making and sTNFR2 were also associated with changes in task-related activity in a network of brain areas, including dorsomedial prefrontal cortex (dmPFC), ventral striatum, and putamen, as well as the functional connectivity between these regions. Changes in sTNFR2 also mediated the relationships between drug condition and behavioral and neuroimaging measures. Finally, changes in self-reported anhedonia symptoms and effort-discounting behavior were associated with greater responses of an independently validated whole-brain predictive model (aka "neural signature") sensitive to monetary rewards. Taken together, these data support the use of anti-inflammatory treatment to improve effort-based decision-making and associated brain circuitry in depressed patients with high inflammation.

NSAID medication mediates the causal effect of genetically predicted major depressive disorder on falls: Evidence from a Mendelian randomization study

BACKGROUND

Increasing evidence supports that depression including major depressive disorder (MDD) is associated with an increased risk of falls. However, some studies suggest no association between MDD and falls. Therefore, the specific causal relationship whereby MDD affects the risk of falls remains elusive, and the potential mediators are unclear.

METHODS

Summary-level data for MDD and falls were collected from the Genome-wide association studies (GWAS) in this study. Mendelian randomization (MR) and multivariable MR (MVMR) analyses were performed to evaluate the causal associations between MDD and falls. A Two-step MR analysis was employed to analyze the mediating effect of nonsteroidal anti-inflammatory drugs (NSAIDs) on the causal association between MDD and the risk of falls.

RESULTS

Using the inverse-variance weighted (IVW) method, genetically predicted MDD was associated with an increased risk of falls (β = 0.15, SE = 0.034; P = 1.61E-5). MVMR and two-step MR analyses demonstrated that MDD was a causal determinant of increased falls independent of body mass index (BMI), smoking initiation, and alcohol consumption and that this causal relationship was mediated by NSAID medication.

LIMITATIONS

Extracted GWAS summary statistics are from European ancestry. Stratified analyses by sex and age were not included in our study. Therefore, it is unclear whether the results are the same for other ethnic groups, genders, and ages.

CONCLUSIONS

Our results demonstrate that MDD is independently associated with an increased risk of falls, in which NSAIDs mediate the association. This study suggests that avoiding the use of NSAIDs may reduce the risk of falls in patients diagnosed with MDD.

Sex-specific gene expression differences in the prefrontal cortex of major depressive disorder individuals

Major depressive disorder (MDD) is a leading global cause of disability, being more prevalent in females, possibly due to molecular and neuronal pathway differences between females and males. However, the connection between transcriptional changes and MDD remains unclear. We identified transcriptionally altered genes (TAGs) in MDD through gene and transcript expression analyses, focusing on sex-specific differences. Analyzing 263 brain samples from both sexes, we conducted differential gene expression, differential transcript expression, and differential transcript usage analyses, revealing 1169 unique TAGs, primarily in the prefrontal areas, with nearly half exhibiting transcript-level alterations. Females showed notable RNA splicing and export process disruptions in the orbitofrontal cortex, alongside altered DDX39B gene expression in five of the six brain regions in both sexes. Our findings suggest that disruptions in RNA processing pathways may play a vital role in MDD.

Peripheral CD4+ T helper lymphocytes alterations in major depressive disorder: A systematic review and meta-analysis

Previous research has shown that patients with major depressive disorder (MDD) develop immune dysfunction. However, the exact alterations of cluster of differentiation (CD)4+ T helper (Th) lymphocytes in MDD remains unclear. This meta-analysis aimed to examine the specific changes in CD4+ Th cells. A comprehensive search of PubMed, EMBASE, Web of Science, and PsycINFO databases was conducted to identify studies investigating CD4+ Th, Th1, Th2, Th17, and T regulatory (Treg) cell counts in the peripheral blood of MDD patients and healthy controls (HCs), covering the period up to June 22, 2024. Our findings revealed that patients with MDD might exhibit higher CD4+ Th cells (SMD=0.26, 95 %CI, 0.02 to 0.50), CD4+/CD8+ cell ratios (SMD=0.51, 95 %CI, 0.14 to 0.89), Th1/Th2 cell ratios (SMD=0.15, 95 %CI, 0.01 to 0.30) and lower Th1 (SMD=-0.17, 95 %CI, -0.30 to -0.03), Th2 (SMD=-0.25, 95 %CI, -0.40 to -0.11), and Treg cells (SMD=-0.69, 95 %CI, -1.27 to -0.11). However, no significant difference was observed in terms of Th17 cells and Th17/Treg cell ratios between MDD patients and the HCs. Heterogeneity was large (I2:18.1-95.2 %), and possible sources of heterogeneity were explored (e.g., age, depression scale, country, and antidepressant use). Our findings indicate that peripheral CD4+ T cells in depressed patients exhibit features of adaptive immune dysfunction, as evidenced by increased CD4+ Th cells and CD4+/CD8+ and decreased Treg cells. These findings offer insights into the underlying mechanism of MDD.

Association of the Serotonin and Kynurenine Pathways as Possible Therapeutic Targets to Modulate Pain in Patients with Fibromyalgia

Fibromyalgia (FM) is a disorder characterized by widespread chronic pain, significant depression, and various neural abnormalities. Recent research suggests a reciprocal exacerbation mechanism between chronic pain and depression. In patients with FM, dysregulation of tryptophan (Trp) metabolism has been identified. Trp, an essential amino acid, serves as a precursor to serotonin (5-HT), a neuromodulator that influences mood, appetite, sleep, and pain perception through the receptors 5-HT1, 5-HT2, and 5-HT3. Additionally, Trp is involved in the kynurenine pathway, a critical route in the immune response, inflammation, and production of neuroactive substances and nicotinamide adenine dinucleotide (NAD+). The activation of this pathway by pro-inflammatory cytokines, such as tumor necrosis factor α (TNF-α) and interferon gamma (IFN-γ), leads to the production of kynurenic acid (KYNA), which has neuroprotective properties, and quinolinic acid (QA), which is neurotoxic. These findings underscore the crucial balance between Trp metabolism, 5-HT, and kynurenine, where an imbalance can contribute to the dual burden of pain and depression in patients with FM. This review proposes a novel therapeutic approach for FM pain management, focusing on inhibiting QA synthesis while co-administering selective serotonin reuptake inhibitors to potentially increase KYNA levels, thus dampening pain perception and improving patient outcomes.

Revealing genetic causality between blood-based biomarkers and major depression in east Asian ancestry

Introduction

Major Depression (MD) is a common mental disorder. In East Asian ancestry, the association, causality, and shared genetic basis between blood-based biomarkers and MD remain unclear.

Methods

We investigated the relationships between blood-based biomarkers and MD through a cross-sectional study and Mendelian randomization (MR) analysis. Cross-trait analysis and enrichment analyses were used to highlight the shared genetic determinants and biological pathways. We conducted summary data-based MR to identify shared genes, which were then validated using a transcriptome dataset from drug-naïve patients with MD.

Results

In the cross-sectional study, C-Reactive Protein showed the significantly positive correlation with depressive symptoms, while hematocrit, hemoglobin, and uric acid exhibited significantly negative correlations. In MR analysis, basophil count (BASO) and low-density lipoprotein cholesterol (LDLc) had a significant causal effect on MD. The enrichment analysis indicated a significant role of inflammatory cytokines and oxidative stress. The shared genes MFN2, FAM55C, GCC2, and SCAPER were validated, with MFN2 identified as a pleiotropic gene involved in MD, BASO, and LDLc.

Discussion

This study highlighted that BASO and LDLc have a causal effect on MD in East Asian ancestry. The pathological mechanisms of MD are related not only to inflammatory cytokines and oxidative stress but also to down regulation of MFN2 expression and mitochondrial dysfunction.

Mesenchymal stem cells improve depressive disorder via inhibiting the inflammatory polarization of microglia

Depressive disorder (DD) ranks among the most prevalent, burdensome, and costly psychiatric conditions globally. It manifests through a range of emotional, cognitive, somatic, and behavioral symptoms. Mesenchymal Stem Cells (MSCs) have garnered significant attention due to their therapeutic potential via immunomodulation in neurological disorders. Our research indicates that MSCs treatment demonstrates a notable effect on a Chronic Unpredictable Mild Stress (CUMS)-induced DD model in mice, surpassing even Fluoxetine in its antidepressant efficacy. MSCs mitigate DD by inhibiting central nervous system inflammation and facilitating the conversion of microglial cells into an Arg1high anti-inflammatory state. The MSCs-derived TGF-β1 is crucial for this Arg1high microglial cell transformation in DD treatment.

Do inflammation and relational motivation coordinate having better sex? The interplay between C-reactive protein and relational approach motivation on sexual well-being

Much evidence on heightened inflammation and social behavior focuses on social withdrawal. Building on recent theory (Muscatell and Inagaki, 2021), we focused instead on the socially affiliative experience of sex. We investigated the interplay between immunology and motivation on sexual well-being among 158 individuals in romantic relationships. Inflammation, indexed by C-reactive protein (CRP), and sexual well-being were measured multiple times over a month. Relational approach motivation (i.e., motivation toward rewards in relationships) was measured at study entry. Results revealed significant associations between CRP and sexual satisfaction and partnered orgasms frequency for those most motivated to approach rewards with their partner. Interaction effects were replicated with relationship-focused psychological correlates of sexual well-being (e.g., touch, shared laughter, social support), but not with individual-focused outcomes (e.g., adapting to change, goal progress). This is one of the first human studies to demonstrate the body and mind coordinate to promote satisfying sexual experiences within romantic relationships.

Development and external validation of a risk prediction model for depression in patients with coronary heart disease

BACKGROUND

Depression is an independent risk factor for adverse outcomes of coronary heart disease (CHD). This study aimed to develop a depression risk prediction model for CHD patients.

METHODS

This study utilized data from the National Health and Nutrition Examination Survey (NHANES). In the training set, reference literature, logistic regression, LASSO regression, optimal subset algorithm, and machine learning random forest algorithm were employed to screen prediction variables, respectively. The optimal prediction model was selected based on the C-index, Net Reclassification Improvement (NRI), and Integrated Discrimination Improvement (IDI). A nomogram for the optimal prediction model was constructed. 3 external validations were performed.

RESULTS

The training set comprised 1375 participants, with a depressive symptoms prevalence of 15.2 %. The optimal prediction model was constructed using predictors obtained from optimal subsets algorithm (C-index = 0.774, sensitivity = 0.751, specificity = 0.685). The model includes age, gender, education, marriage, diabetes, tobacco use, antihypertensive drugs, high-density lipoprotein cholesterol (HDLC), and aspartate aminotransferase (AST). The model demonstrated consistent discrimination ability, accuracy, and clinical utility across the 3 external validations.

LIMITATIONS

The applicable population of the model is CHD patients. And the clinical benefits of interventions based on the prediction results are still unknown.

CONCLUSION

We developed a depression risk prediction model for CHD patients, which was presented in the form of a nomogram for clinical application.

RIPK1 inhibition mitigates neuroinflammation and rescues depressive-like behaviors in a mouse model of LPS-induced depression

BACKGROUND

Depression is often linked to inflammation in the brain. Researchers have been exploring ways to reduce this inflammation to improve depression symptoms. One potential target is a protein called RIPK1, which is known to contribute to brain inflammation. However, it's unclear how RIPK1 influences depression. Our study aims to determine whether RIPK1 inhibition could alleviate neuroinflammation-associated depression and elucidate its underlying mechanisms.

METHODS

To investigate our research objectives, we established a neuroinflammation mouse model by administering LPS. Behavioral and biochemical assessments were conducted on these mice. The findings were subsequently validated through in vitro experiments.

RESULTS

Using LPS-induced depression models, we investigated RIPK1's role, observing depressive-like behaviors accompanied by elevated cytokines, IBA-1, GFAP levels, and increased inflammatory signaling molecules and NO/H2O2. Remarkably, Necrostatin (Nec-1 S), a RIPK1 inhibitor, mitigated these changes. We further found altered expression and phosphorylation of eIF4E, PI3K/AKT/mTOR, and synaptic proteins in hippocampal tissues, BV2, and N2a cells post-LPS treatment, which Nec-1 S also ameliorated. Importantly, eIF4E inhibition reversed some of the beneficial effects of Nec-1 S, suggesting a complex interaction between RIPK1 and eIF4E in LPS-induced neuroinflammation. Moreover, citronellol, a RIPK1 agonist, significantly altered eIF4E phosphorylation, indicating RIPK1's potential upstream regulatory role in eIF4E and its contribution to neuroinflammation-associated depression.

CONCLUSION

These findings propose RIPK1 as a pivotal mediator in regulating neuroinflammation and neural plasticity, highlighting its significance as a potential therapeutic target for depression.

Inflammation-stratified augmentation of vortioxetine with celecoxib: Results from a double-blind, randomized, placebo-controlled trial in major depressive disorder

Low-grade inflammation is considered as a pathophysiological mechanism in a subtype of patients with major depressive disorder (MDD). Anti-inflammatory drugs have shown efficacy in treating MDD. However, it remains unclear how to identify suitable patients for anti-inflammatory treatment of depression. This study investigates the predictive value of pre-treatment high-sensitivity C-Reactive Protein (hsCRP) stratification on the outcome of celecoxib augmentation of vortioxetine. The PREDDICT study was conducted as a randomized, double-blind, placebo-controlled 6-week trial on augmentation of vortioxetine with celecoxib between December 2017 and April 2020 at the University of Adelaide (Australia). The present analysis focusses on the question of whether the pre-treatment hsCRP measurement and stratification of patients to depression with inflammation (hsCRP >3 mg/L) or without inflammation (hsCRP ≤3 mg/L) has an impact on the outcome of anti-inflammatory treatment with celecoxib. A total of n = 119 mostly treatment-resistant MDD patients with moderate to severe symptomatology were recruited in the trial. There was no effect of treatment group (celecoxib or placebo), pre-treatment hsCRP strata (with/without inflammation), or interaction between the two terms on treatment outcome. The results of the current analysis do not support the hypothesis that pre-treatment hsCRP level is predictive for response to anti-inflammatory treatment with celecoxib in MDD patients. Further research is needed to identify appropriate biomarkers for the prediction of anti-inflammatory treatment outcome in depression. CLINICAL TRIALS REGISTRATION: Australian New Zealand Clinical Trials Registry (ANZCTR), ACTRN12617000527369p. Registered on 11 April 2017, http://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=12617000527369p.

A Potential Role for MAGI-1 in the Bi-Directional Relationship Between Major Depressive Disorder and Cardiovascular Disease

PURPOSE OF REVIEW

Major Depressive Disorder (MDD) is characterized by persistent symptoms such as fatigue, loss of interest in activities, feelings of sadness and worthlessness. MDD often coexist with cardiovascular disease (CVD), yet the precise link between these conditions remains unclear. This review explores factors underlying the development of MDD and CVD, including genetic, epigenetic, platelet activation, inflammation, hypothalamic-pituitary-adrenal (HPA) axis activation, endothelial cell (EC) dysfunction, and blood-brain barrier (BBB) disruption.

RECENT FINDINGS

Single nucleotide polymorphisms (SNPs) in the membrane-associated guanylate kinase WW and PDZ domain-containing protein 1 (MAGI-1) are associated with neuroticism and psychiatric disorders including MDD. SNPs in MAGI-1 are also linked to chronic inflammatory disorders such as spontaneous glomerulosclerosis, celiac disease, ulcerative colitis, and Crohn's disease. Increased MAGI-1 expression has been observed in colonic epithelial samples from Crohn's disease and ulcerative colitis patients. MAGI-1 also plays a role in regulating EC activation and atherogenesis in mice and is essential for Influenza A virus (IAV) infection, endoplasmic reticulum stress-induced EC apoptosis, and thrombin-induced EC permeability. Despite being understudied in human disease; evidence suggests that MAGI-1 may play a role in linking CVD and MDD. Therefore, further investigation of MAG-1 could be warranted to elucidate its potential involvement in these conditions.

Hypericum perforatum L. attenuates depression by regulating Akkermansia muciniphila, tryptophan metabolism and NFκB-NLRP2-Caspase1-IL1β pathway

BACKGROUND

Gut microbiota dysbiosis significantly contributes to progression of depression. Hypericum perforatum L. (HPL) is traditionally used in Europe for treating depression. However, its mechanism remains largely underexplored.

PURPOSE

This study aims to investigate the pivotal gut microbiota species and microbial signaling metabolites associated with the antidepressant effects of HPL.

METHODS

Fecal microbiota transplantation was used to assess whether HPL mitigates depression through alterations in gut microbiota. Microbiota and metabolic profiling of control, chronic restraint stress (CRS)-induced depression, and HPL-treated CRS mice were examined using 16S rRNA gene sequencing and metabolomics analysis. The influence of gut microbiota on HPL's antidepressant effects was assessed by metabolite and bacterial intervention experiments.

RESULTS

HPL significantly alleviated depression symptoms in a manner dependent on gut microbiota and restored gut microbial composition by enriching Akkermansia muciniphila (AKK). Metabolomic analysis indicated that HPL regulated tryptophan metabolism, reducing kynurenine (KYN) levels derived from microbiota and increasing 5-hydroxytryptophan (5-HTP) levels. Notably, supplementation with KYN activated the NFκB-NLRP2-Caspase1-IL1β pathway and increased proinflammatory IL1β in the hippocampus of mice with depression. Interestingly, mono-colonization with AKK notably increased 5-hydroxytryptamine (5-HT) and decreased KYN levels, ameliorating depression symptoms through modulation of the NFκB-NLRP2-Caspase1-IL1β pathway.

CONCLUSIONS

The promising therapeutic role of HPL in treating depression is primarily attributed to its regulation of the NFκB-NLRP2-Caspase1-IL1β pathway, specifically by targeting AKK and tryptophan metabolites.

Stress and cardiovascular disease: an update

Psychological stress is generally accepted to be associated with an increased risk of cardiovascular disease (CVD), but results have varied in terms of how stress is measured and the strength of the association. Additionally, the mechanisms and potential causal links have remained speculative despite decades of research. The physiological responses to stress are well characterized, but their contribution to the development and progression of CVD has received little attention in empirical studies. Evidence suggests that physiological responses to stress have a fundamental role in the risk of CVD and that haemodynamic, vascular and immune perturbations triggered by stress are especially implicated. Stress response physiology is regulated by the corticolimbic regions of the brain, which have outputs to the autonomic nervous system. Variation in these regulatory pathways might explain interindividual differences in vulnerability to stress. Dynamic perturbations in autonomic, immune and vascular functions are probably also implicated as CVD risk mechanisms of chronic, recurring and cumulative stressful exposures, but more data are needed from prospective studies and from assessments in real-life situations. Psychological assessment remains insufficiently recognized in clinical care and prevention. Although stress-reduction interventions might mitigate perceived stress levels and potentially reduce cardiovascular risk, more data from randomized trials are needed.

Antidepressant-like effect of riparin I and riparin II against CUMS-induced neuroinflammation via astrocytes and microglia modulation in mice

Depression is a common mood disorder and many patients do not respond to conventional pharmacotherapy or experience a variety of adverse effects. This work proposed that riparin I (RIP I) and riparin II (RIP II) present neuroprotective effects through modulation of astrocytes and microglia, resulting in the reversal of depressive-like behaviors. To verify our hypothesis and clarify the pathways underlying the effect of RIP I and RIP II on neuroinflammation, we used the chronic unpredictable mild stress (CUMS) depression model in mice. Male Swiss mice were exposed to stressors for 28 days. From 15 th to the 22 nd day, the animals received RIP I or RIP II (50 mg/kg) or fluoxetine (FLU, 10 mg/kg) or vehicle, by gavage. On the 29 th day, behavioral tests were performed. Expressions of microglia (ionized calcium-binding adaptor molecule-1 - Iba-1) and astrocyte (glial fibrillary acidic protein - GFAP) markers and levels of cytokines tumor necrosis factor alfa (TNF-α) and interleukin 1 beta (IL-1β) were measured in the hippocampus. CUMS induced depressive-like behaviors and cognitive impairment, high TNF-α and IL-1β levels, decreased GFAP, and increased Iba-1 expressions. RIP I and RIP II reversed these alterations. These results contribute to the understanding the mechanisms underlying the antidepressant effect of RIP I and RIP II, which may be related to neuroinflammatory suppression.

Could the periodontal therapy improve the cardiologic patient health? A narrative review

BACKGROUND

Cardiovascular diseases (CVD) is the major cause of mortality globally, with increasing evidence suggesting a link between periodontitis, and CVD. This study aims to explore the association between periodontitis and CVD, and the impact of periodontal therapy on cardiovascular health.

METHODS

This review synthesized findings from preclinical and clinical studies, without publication year restrictions, examining periodontitis and CVD through various lenses. Scientific databases were inspected with keywords related to periodontitis and CVD.

RESULTS

The review identifies a substantial association between periodontitis and an increased risk of several CVD, supported by both epidemiological and interventional studies. Results suggest the complexity of the relationship, influenced by factors like the severity of periodontitis and the presence of other systemic conditions. Clinical data indicates that periodontal therapy, particularly non-surgical periodontal therapy, may reduce systemic inflammatory markers and thus may play a role in the primary and secondary prevention of CVD events, highlighting the potential of periodontal therapy to not only maintain oral health but also to modulate cardiovascular risk factors.

CONCLUSIONS

Current evidence supports a significant association between periodontitis and increased cardiovascular risk, promoting integrated healthcare approaches that consider oral health as a key-component of cardiovascular care and wellbeing.

Microglial NLRP3 inflammasome-mediated neuroinflammation and therapeutic strategies in depression

Previous studies have demonstrated a bidirectional relationship between inflammation and depression. Activation of the nucleotide-binding oligomerization domain, leucine-rich repeat, and NLR family pyrin domain-containing 3 (NLRP3) inflammasomes is closely related to the pathogenesis of various neurological diseases. In patients with major depressive disorder, NLRP3 inflammasome levels are significantly elevated. Understanding the role that NLRP3 inflammasome-mediated neuroinflammation plays in the pathogenesis of depression may be beneficial for future therapeutic strategies. In this review, we aimed to elucidate the mechanisms that lead to the activation of the NLRP3 inflammasome in depression as well as to provide insight into therapeutic strategies that target the NLRP3 inflammasome. Moreover, we outlined various therapeutic strategies that target the NLRP3 inflammasome, including NLRP3 inflammatory pathway inhibitors, natural compounds, and other therapeutic compounds that have been shown to be effective in treating depression. Additionally, we summarized the application of NLRP3 inflammasome inhibitors in clinical trials related to depression. Currently, there is a scarcity of clinical trials dedicated to investigating the applications of NLRP3 inflammasome inhibitors in depression treatment. The modulation of NLRP3 inflammasomes in microglia holds promise for the management of depression. Further investigations are necessary to ascertain the efficacy and safety of these therapeutic approaches as potential novel antidepressant treatments.

Exploring the pathogenesis and treatment of PSD from the perspective of gut microbiota

Post-stroke depression (PSD) is a psychological disease that can occur following a stroke and is associated with serious consequences. Research on the pathogenesis and treatment of PSD is still in the infancy stage. Patients with PSD often exhibit gastrointestinal symptoms; therefore the role of gut microbiota in the pathophysiology and potential treatment effects of PSD has become a hot topic of research. In this review, describe the research on the pathogenesis and therapy of PSD. We also describe how the gut microbiota influences neurotransmitters, the endocrine system, energy metabolism, and the immune system. It was proposed that the gut microbiota is involved in the pathogenesis and treatment of PSD through the regulation of neurotransmitter levels, vagal signaling, hypothalamic-pituitary-adrenal axis activation and inhibition, hormone secretion and release, in addition to immunity and inflammation.

Does tinnitus amplify the effects of healthy eating patterns and physical activity on the sleep disturbance or sleep insufficiency, based on the case study of NHANES survey in the United States

Objective

Exploring whether the presence of tinnitus amplifies the effects of an individual's dietary patterns and physical activity on sleep disturbance or sleep insufficiency.

Study design

This study extracted data from the five National Health and Nutrition Examination Surveys (NHANES) between 2009 and 2018, including individuals who had undergone complete questionnaires on tinnitus, dietary habits, physical activity, and sleep. Multivariate logistic regression, restricted cubic spline (RCS) and subgroup analyses were conducted to explore the associations of dietary habits, physical activity, and tinnitus with sleep disturbance and sleep insufficiency.

Results

A total of 7,440 participants were enrolled in this study, of whom 1,795 participants were evaluated as sleep disturbance (24.13%), and 2,281 were sleep insufficiency (30.66%). With adjusting confounding factors of demographic and socioeconomic variables, among overall population, participants with tinnitus showed a significantly increased risk of sleep disturbance [adjusted odds ratio (aOR) = 2.08, 95% confidence interval (CI): 1.83-2.36), and sleep insufficiency (aOR = 1.31, 95% CI: 1.15-1.49). Poor dietary habits also increased the risk of sleep disturbance (aOR = 1.08, 95% CI: 1.04-1.12), as does lack of physical activity (aOR = 1.14, 95% CI: 1.03-1.27); but neither exposure factors significantly increased the risk of sleep insufficiency. The non-linear trend analyses of RCS found that the influence of exposure factors on sleep disturbance experiencing a steady or small decline trend after rising. In addition, the results of the subgroup analysis showed that in tinnitus patients, poor dietary habits and lack of physical activity both significantly increased the risk of sleep disturbance, and poor dietary habits also increased the risk of sleep insufficiency remarkable, but lack of physical activity did not. In healthy participants, poor dietary habits were only significantly associated the sleep disturbance, while lack of physical inactivity even had a protective effect against sleep insufficiency.

Conclusion

Compared to the general population, tinnitus significantly amplified the effects of poor dietary patterns and physical inactivity on sleep disturbance and sleep insufficiency. For tinnitus patients, adjusting a healthy diet and increasing exercise could more effectively promote their sleep health.

Nutritional Strategies in Major Depression Disorder: From Ketogenic Diet to Modulation of the Microbiota-Gut-Brain Axis

Major depressive disorder (MDD) is a leading cause of disability worldwide. While traditional pharmacological treatments are effective for many cases, a significant proportion of patients do not achieve full remission or experience side effects. Nutritional interventions hold promise as an alternative or adjunctive approach, especially for treatment-resistant depression. This review examines the potential role of nutrition in managing MDD through addressing biological deficits and modulating pathways relevant to its pathophysiology. Specifically, it explores the ketogenic diet and gut microbiome modulation through various methods, including probiotics, prebiotics, synbiotics, postbiotics, and fecal microbiota transplantation. Numerous studies link dietary inadequacies to increased MDD risk and deficiencies in nutrients like omega-3 s, vitamins D and B, magnesium, and zinc. These deficiencies impact neurotransmitters, inflammation, and other biological factors in MDD. The gut-brain axis also regulates mood, stress response, and immunity, and disruptions are implicated in MDD. While medications aid acute symptoms, nutritional strategies may improve long-term outcomes by preventing relapse and promoting sustained remission. This comprehensive review aims to provide insights into nutrition's multifaceted relationship with MDD and its potential for developing more effective integrated treatment approaches.

Association between rTMS-induced changes in inflammatory markers and improvement in psychiatric diseases: a systematic review

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) has recently gained relevance in treating different psychiatric disorders. Limited evidence suggests that the beneficial effects of rTMS on psychopathology could be at least partly mediated through changes in inflammatory response. This systematic review summarizes the literature on whether rTMS can modulate inflammatory markers and thus positively influence the course of psychiatric illnesses.

MATERIALS AND METHODS

A systematic review of rTMS and inflammatory markers in psychiatric diseases was conducted according to PRISMA guidelines. Information on the association between rTMS treatment response and changes of inflammatory markers was extracted. The quality of the studies was assessed using the National Heart, Lung, and Blood Institute for human studies and the Systematic Review Center for Laboratory Animal Experimentation for animal studies.

RESULTS

This review includes 17 studies (2 animal and 15 human studies) on the relationship between rTMS treatment response and changes of inflammatory markers. Positive changes in microglial activity and anti-inflammatory effects were associated with behavioral improvement in animal models of depression. However, these findings have not been consistently replicated in human studies focusing on treatment-resistant depression. While several studies reported rTMS-induced alterations in peripheral inflammatory markers, only two could demonstrate their association to clinical treatment response. Notably, most studies showed poor or moderate quality in the bias assessment.

CONCLUSIONS

While certain human studies suggest an association between rTMS-induced anti-inflammatory effects and improvement in psychopathology, heterogeneity, and underpowered analyses constrain the generalizability of these results. The discrepancy between animal and human findings highlights the need for larger, standardized human studies.

TRIAL REGISTRATION

(PROSPERO Registration: CRD42023492732).

Increased expression of ER stress, inflammasome activation, and mitochondrial biogenesis-related genes in peripheral blood mononuclear cells in major depressive disorder

A subset of major depressive disorder (MDD) is characterized by immune system dysfunction, but the intracellular origin of these immune changes remains unclear. Here we tested the hypothesis that abnormalities in endoplasmic reticulum (ER) stress, inflammasome activity and mitochondrial biogenesis contribute to the development of systemic inflammation in MDD. RT-qPCR was used to measure mRNA expression of key organellar genes from peripheral blood mononuclear cells (PBMCs) isolated from 186 MDD and 67 healthy control (HC) subjects. The comparative CT (2-ΔΔCT) method was applied to quantify mRNA expression using GAPDH as the reference gene. After controlling for age, sex, BMI, and medication status using linear regression models, expression of the inflammasome (NLRC4 and NLRP3) and the ER stress (XBP1u, XBP1s, and ATF4) genes was found to be significantly increased in the MDD versus the HC group. Sensitivity analyses excluding covariates yielded similar results. After excluding outliers, expression of the inflammasome genes was no longer statistically significant but expression of the ER stress genes (XBP1u, XBP1s, and ATF4) remained significant and the mitochondrial biogenesis gene, MFN2, was significantly increased in the MDD group. NLRC4 and MFN2 were positively correlated with serum C-reactive protein concentrations, while ASC trended significant. The altered expression of inflammasome activation, ER stress, and mitochondrial biogenesis pathway components suggest that dysfunction of these organelles may play a role in the pathogenesis of MDD.

Unique genetic and risk-factor profiles in clusters of major depressive disorder-related multimorbidity trajectories

The heterogeneity and complexity of symptom presentation, comorbidities and genetic factors pose challenges to the identification of biological mechanisms underlying complex diseases. Current approaches used to identify biological subtypes of major depressive disorder (MDD) mainly focus on clinical characteristics that cannot be linked to specific biological models. Here, we examined multimorbidities to identify MDD subtypes with distinct genetic and non-genetic factors. We leveraged dynamic Bayesian network approaches to determine a minimal set of multimorbidities relevant to MDD and identified seven clusters of disease-burden trajectories throughout the lifespan among 1.2 million participants from cohorts in the UK, Finland, and Spain. The clusters had clear protective- and risk-factor profiles as well as age-specific clinical courses mainly driven by inflammatory processes, and a comprehensive map of heritability and genetic correlations among these clusters was revealed. Our results can guide the development of personalized treatments for MDD based on the unique genetic, clinical and non-genetic risk-factor profiles of patients.