PPAR-γ agonism as a modulator of mood: proof-of-concept for pioglitazone in bipolar depression

Synaptotagmin-7 deficit causes insulin hypoactivity and contributes to behavioral alterations in mice

Synaptotagmin-7 (Syt7) KO mice show diurnal fluctuations of mania- and depression-like behavioral abnormalities. Although GluN2B-NMDAR hypoactivity has been shown to be involved in the induction of mania-like behaviors of the Syt7 KO mice in the dark phase, the reasons for the depression-like behaviors in the light phase and behavioral fluctuation remain unknown. Here, we show that bipolar I disorder (BDI)-patient-induced pluripotent stem cell (iPSC)-derived islet-like organoids exhibited Syt7-dependent insulin secretion defects; moreover, Syt7-deficiency-induced insulin hyposecretion generated depression-like behaviors in Syt7 KO mice in the light phase. Furthermore, pancreatic insulin secretion and neuronal activity showed opposite diurnal patterns, in which the Syt7-deficiency-induced disequilibrium induced periodic antagonistic shifts in the mania- and depression-like behaviors. Finally, using RNA sequencing (RNA-seq) analysis, we explored downstream pathways that might underlie the diurnal fluctuation of behaviors. Therefore, Syt7-deficiency-induced insulin hypoactivity contributed to light-phase depression-like behaviors and diurnal behavioral fluctuations in the mice.

Pharmacotherapeutic value of inflammatory and neurotrophic biomarkers in bipolar disorder: A systematic review

BACKGROUND

The various pharmacological interventions, ranging from mood stabilizers and antipsychotics to antidepressants, reflect the diff/iculty of treating depressive/manic symptomatology of bipolar disorder (BD). Among a broad range of mechanisms implicated, immune dysregulation may contribute to the increased inflammation that influences the course of BD. Inflammatory, neurotrophic and oxidative stress factors may be identified as promising peripheral biomarkers in brain functioning, perhaps serving as predictors of an effective response to treatment for BD. The present systematic review aimed to examine the evidence supporting the pharmacotherapeutic value of inflammatory and neurotrophic biomarkers in BD.

METHODS

PubMed, PsychINFO, Scopus and Web of Science were searched from inception to May 2024 by two independent reviewers. A total of 40 studies with 3371 patients with diagnosis and intervention of BD were selected.

RESULTS

Inconsistencies in the effects of pharmacological treatments on the connection between the expected anti-inflammatory response and symptomatologic improvement were identified. Mood stabilizers (lithium), antipsychotics (quetiapine), antidepressants (ketamine) or their combination were described to increase both pro-inflammatory (TNFα, IL-6) and anti-inflammatory (IL-4, IL-8) factors. Other medications, such as memantine and dextromethorphan, autoimmune (infliximab) non-steroidal anti-inflammatory (aspirin, celecoxib) drugs, antidiabetics (pioglitazone), and even dietary supplementation (omega-3), or their combination, clearly decrease inflammatory factors (TNFα, IL-6, IL-1β, C-reactive protein) and/or increase the neurotrophic factor BDNF in BD patients.

CONCLUSION

Inflammation in BD requires further investigation to understand the underlying immunologic mechanism, to identify predictors of treatment response, and to make informed decisions about the use and development of more effective pharmacological interventions for BD.

Unlocking new avenues for neuropsychiatric disease therapy: the emerging potential of Peroxisome proliferator-activated receptors as promising therapeutic targets

RATIONALE

Peroxisome proliferator-activated receptors (PPARs) are transcription factors that regulate various physiological processes such as inflammation, lipid metabolism, and glucose homeostasis. Recent studies suggest that targeting PPARs could be beneficial in treating neuropsychiatric disorders by modulating neuronal function and signaling pathways in the brain. PPAR-α, PPAR-δ, and PPAR-γ have been found to play important roles in cognitive function, neuroinflammation, and neuroprotection. Dysregulation of PPARs has been associated with neuropsychiatric disorders like bipolar disorder, schizophrenia, major depression disorder, and autism spectrum disorder. The limitations and side effects of current treatments have prompted research to target PPARs as a promising novel therapeutic strategy. Preclinical and clinical studies have shown the potential of PPAR agonists and antagonists to improve symptoms associated with these disorders.

OBJECTIVE

This review aims to provide an overview of the current understanding of PPARs in neuropsychiatric disorders, their potential as therapeutic targets, and the challenges and future directions for developing PPAR-based therapies.

METHODS

An extensive literature review of various search engines like PubMed, Medline, Bentham, Scopus, and EMBASE (Elsevier) databases was carried out with the keywords "PPAR, Neuropsychiatric disorders, Oxidative stress, Inflammation, Bipolar Disorder, Schizophrenia, Major depression disorder, Autism spectrum disorder, molecular pathway".

RESULT & CONCLUSION

Although PPARs present a hopeful direction for innovative therapeutic approaches in neuropsychiatric conditions, additional research is required to address obstacles and convert this potential into clinically viable and individualized treatments.

Association of METS-IR index with depressive symptoms in US adults: A cross-sectional study

BACKGROUND

An association between insulin resistance (IR) and depression has been identified in recent years. The purpose of this study was to examine the relationship between IR and depression in the general population.

METHODS

The population for this cross-sectional study consisted of adults participating in the National Health and Nutrition Examination Survey (NHANES) between 2005 and 2018. Insulin sensitivity was assessed using the Metabolic Score for IR (METS-IR) index, while depression was evaluated using the Patient Health Questionnaire (PHQ)-9. Logistic regression analyses, subgroup analyses, and dose-response curves were conducted to assess the association between the METS-IR index and depression.

RESULTS

A total of 13,157 adults aged over 20 years were included in this study. After adjusting for potential confounders, it was observed that each unit increase in the METS-IR index was associated with a 1.1 percentage point increase in the prevalence of depression (OR = 1.011; 95 % CI: 1.008, 1.014). Patients in the 4th quartile of the METS-IR index had a higher likelihood of depression compared to those in the 1st quartile (OR = 1.386, 95 % CI: 1.239, 1.549). Stratified analyses demonstrated consistent results in all subgroups, except for men, patients under 40 years of age, and those with a history of cancer. Dose-response curves indicated a nonlinear relationship between the METS-IR index and the risk of depression, with an inflection point value of 32.443 according to threshold effect analysis.

CONCLUSIONS

Our findings suggest that higher METS-IR scores are associated with an increased likelihood of experiencing depressive symptoms among U.S. adults.

Predicting Conversion to Insulin Sensitivity With Metformin: A Promising Tool for Clinicians in Addressing Insulin Resistance and Improving Outcomes in Patients With Treatment Resistant Bipolar Depression

BACKGROUND

Insulin resistance (IR) changes the trajectory of responsive bipolar disorder to a treatment-resistant course. A clinical trial conducted by our group demonstrated that IR reversal by metformin improved clinical and functional outcomes in treatment-resistant bipolar depression (TRBD). To aid clinicians identify which metformin-treated TRBD patients might reverse IR, and given strong external evidence for their association with IR, we developed a predictive tool using body mass index (BMI) and homeostatic model assessment-insulin resistance (HOMA-IR).

METHODS

The predictive performance of baseline BMI and HOMA-IR was tested with a logistic regression model using known metrics: area under the receiver operating curve, sensitivity, and specificity. In view of the high benefit to low risk of metformin in reversing IR, high sensitivity was favored over specificity.

RESULTS

In this BMI and HOMA-IR model for IR reversal, the area under the receiver operating curve is 0.79. At a cutoff probability of conversion of 0.17, the model's sensitivity is 91% (95% confidence interval [CI], 57%-99%), and the specificity is 56% (95% CI, 36%-73%). For each unit increase in BMI or HOMA-IR, there is a 15% (OR, 0.85; 95% CI, 0.71-0.99) or 43% (OR, 0.57; CI, 0.18-1.36) decrease in the odds of conversion, respectively.

CONCLUSIONS

In individuals with TRBD, this tool using BMI and HOMA-IR predicts IR reversal with metformin with high sensitivity. Furthermore, these data suggest early intervention with metformin at lower BMI, and HOMA-IR would likely reverse IR in TRBD.

Efficacy and Safety of Antidiabetic Agents for Major Depressive Disorder and Bipolar Depression: A Meta-Analysis of Randomized, Double-Blind, Placebo-Controlled Trials

BACKGROUND

This meta-analysis aimed to determine the efficacy and safety of antidiabetic agents in the treatment of major depressive disorder and bipolar depression.

METHODS

Randomized controlled trials (RCTs) of antidiabetic agents in major depressive disorder or bipolar depression were searched in three electronic databases and three clinical trial registry websites from their inception up to October 2023. The differences in changes in the depression rating scale scores from baseline to endpoint or pre-defined sessions, response rate, remission rate, rate of side effects and dropout rate between antidiabetic agents and placebo were meta-analyzed.

RESULTS

Six RCTs involving 399 participants were included in the final meta-analysis, which did not find that antidiabetics outperformed the placebo in reducing depressive symptoms. The standardized mean difference (SMD) in the depression scores from baseline to endpoint was 0.25 (95% CI -0.1, 0.61). However, a subgroup analysis found a significant difference between antidiabetics and placebos in reducing depressive symptoms in Middle Eastern populations, with an SMD of 0.89 (95% CI 0.44, 1.34).

CONCLUSIONS

The current meta-analysis does not support the efficacy of antidiabetics being superior to the placebo in the treatment of unipolar and bipolar depression. However, a subgroup analysis indicates that patients from the Middle East may benefit from adding an antidiabetic medication to their ongoing medication(s) for their depression. Larger studies with good-quality study designs are warranted.

The role of polyunsaturated fatty acids in the neurobiology of major depressive disorder and suicide risk

Long-chain polyunsaturated fatty acids (LC-PUFAs) are obtained from diet or derived from essential shorter-chain fatty acids, and are crucial for brain development and functioning. Fundamentally, LC-PUFAs' neurobiological effects derive from their physicochemical characteristics, including length and double bond configuration, which differentiate LC-PUFA species and give rise to functional differences between n(omega)-3 and n-6 LC-PUFAs. LC-PUFA imbalances are implicated in psychiatric disorders, including major depression and suicide risk. Dietary intake and genetic variants in enzymes involved in biosynthesis of LC-PUFAs from shorter chain fatty acids influence LC-PUFA status. Domains impacted by LC-PUFAs include 1) cell signaling, 2) inflammation, and 3) bioenergetics. 1) As major constituents of lipid bilayers, LC-PUFAs are determinants of cell membrane properties of viscosity and order, affecting lipid rafts, which play a role in regulation of membrane-bound proteins involved in cell-cell signaling, including monoaminergic receptors and transporters. 2) The n-3:n-6 LC-PUFA balance profoundly influences inflammation. Generally, metabolic products of n-6 LC-PUFAs (eicosanoids) are pro-inflammatory, while those of n-3 LC-PUFAs (docosanoids) participate in the resolution of inflammation. Additionally, n-3 LC-PUFAs suppress microglial activation and the ensuing proinflammatory cascade. 3) N-3 LC-PUFAs in the inner mitochondrial membrane affect oxidative stress, suppressing production of and scavenging reactive oxygen species (ROS), with neuroprotective benefits. Until now, this wealth of knowledge about LC-PUFA biomechanisms has not been adequately tapped to develop translational studies of LC-PUFA clinical effects in humans. Future studies integrating neurobiological mechanisms with clinical outcomes may suggest ways to identify depressed individuals most likely to respond to n-3 LC-PUFA supplementation, and mechanistic research may generate new treatment strategies.

The association between insulin resistance and depressive symptoms - A national representative cross-sectional study

OBJECTIVE

Increasing evidence suggests a positive association between insulin resistance (IR) and depression. However, whether sex-or body mass index-specific differences exist remains controversial, and only few studies have analyzed specific symptom domains. Thus, the present study aimed to analyze the association between IR and depressive symptom domains and to clarify the effects of sex and body mass index.

METHODS

The study sample comprised 4007 participants, aged 19-79, from the Korea National Health and Nutrition Examination Study 2020. Participants completed health interviews and examinations, providing data on circulating insulin and glucose levels, the Patient Health Questionnaire-9 (PHQ-9), and related covariates. IR was calculated using the homeostasis model assessment of insulin resistance. Associations between IR and PHQ-9 were analyzed using negative binomial regression with adjustments for the complex survey design.

RESULTS

The association between log-transformed IR and PHQ-9 total scores was statistically significant (incidence rate ratio [IRR] = 1.17, 95% confidence interval [CI] = 1.07-1.29, p = 0.001). Only body mass index specific differences were statistically significant, as the association was only significant in those without obesity (IRR = 1.21, 95% CI = 1.06-1.38, p = 0.005). IR was associated with cognitive/affective (IRR = 1.23, 95% CI = 1.08-1.41, p = 0.002) and somatic (IRR = 1.14, 95% CI = 1.04-1.25, p = 0.005) depressive symptom domains. Sensitivity analyses revealed similar results.

CONCLUSIONS

IR was positively associated with cognitive/affective and somatic depressive symptoms in non-obese individuals.

Integrating Metabolomics and Network Pharmacology to Explore the Mechanism of Xiao-Yao-San in the Treatment of Inflammatory Response in CUMS Mice

Depression can trigger an inflammatory response that affects the immune system, leading to the development of other diseases related to inflammation. Xiao-Yao-San (XYS) is a commonly used formula in clinical practice for treating depression. However, it remains unclear whether XYS has a modulating effect on the inflammatory response associated with depression. The objective of this study was to examine the role and mechanism of XYS in regulating the anti-inflammatory response in depression. A chronic unpredictable mild stress (CUMS) mouse model was established to evaluate the antidepressant inflammatory effects of XYS. Metabolomic assays and network pharmacology were utilized to analyze the pathways and targets associated with XYS in its antidepressant inflammatory effects. In addition, molecular docking, immunohistochemistry, Real-Time Quantitative Polymerase Chain Reaction (RT-qPCR), and Western Blot were performed to verify the expression of relevant core targets. The results showed that XYS significantly improved depressive behavior and attenuated the inflammatory response in CUMS mice. Metabolomic analysis revealed the reversible modulation of 21 differential metabolites by XYS in treating depression-related inflammation. Through the combination of liquid chromatography and network pharmacology, we identified seven active ingredients and seven key genes. Furthermore, integrating the predictions from network pharmacology and the findings from metabolomic analysis, Vascular Endothelial Growth Factor A (VEGFA) and Peroxisome Proliferator-Activated Receptor-γ (PPARG) were identified as the core targets. Molecular docking and related molecular experiments confirmed these results. The present study employed metabolomics and network pharmacology analyses to provide evidence that XYS has the ability to alleviate the inflammatory response in depression through the modulation of multiple metabolic pathways and targets.

Toward a Precision Treatment Approach for Metabolic Depression: Integrating Epidemiology, Neuroscience, and Psychiatry

Background

Individuals with comorbid major depressive disorder and type 2 diabetes represent an important subgroup of patients for whom conventional treatment may be insufficient. A precision treatment approach that addresses insulin resistance with an outcome of a positive response to antidepressants may prove beneficial.

Methods

This study utilized an emulated target trial on a large dataset from the Optum Clinformatics Data Mart Database. We evaluated the effect of adjuvant pioglitazone, an insulin-sensitizing drug, on antidepressant response among 4696 people with type 2 diabetes, comparing it with DPP4 (dipeptidyl peptidase-4) inhibitors (non-insulin-sensitizing). An additional analysis involving 6518 participants was conducted to assess the efficacy of pioglitazone versus sulfonylureas.

Results

The instrumental variable analysis indicated that the initiation of an antidepressant with pioglitazone was superior to DPP4 inhibitors in terms of antidepressant response, with fewer treatment shifts and/or additions of new antidepressant or antipsychotic over a 1-year period. This result was consistent when pioglitazone was compared with sulfonylureas in a supplemental analysis.

Conclusions

Our findings suggest that pioglitazone may be more effective than DPP4 inhibitors or sulfonylureas in enhancing antidepressant response among people with comorbid major depressive disorder and type 2 diabetes. This provides a strong case for the use of pioglitazone in patients with these conditions, emphasizing the potential of precision medicine strategies. The results should be interpreted with caution due to inherent limitations associated with observational data.

Clinical insights into the cross-link between mood disorders and type 2 diabetes: A review of longitudinal studies and Mendelian randomisation analyses

Mood disorders and type 2 diabetes mellitus (T2DM) are prevalent conditions that often co-occur. We reviewed the available evidence from longitudinal and Mendelian randomisation (MR) studies on the relationship between major depressive disorder (MDD), bipolar disorder and T2DM. The clinical implications of this comorbidity on the course of either condition and the impact of antidepressants, mood stabilisers, and antidiabetic drugs were examined. Consistent evidence indicates a bidirectional association between mood disorders and T2DM. T2DM leads to more severe depression, whereas depression is associated with more complications and higher mortality in T2DM. MR studies demonstrated a causal effect of MDD on T2DM in Europeans, while a suggestive causal association in the opposite direction was found in East Asians. Antidepressants, but not lithium, were associated with a higher T2DM risk in the long-term, but confounders cannot be excluded. Some oral antidiabetics, such as pioglitazone and liraglutide, may be effective on depressive and cognitive symptoms. Studies in multi-ethnic populations, with a more careful assessment of confounders and appropriate power, would be important.

Cannabidiol goes nuclear: The role of PPARγ

BACKGROUND

Cannabidiol (CBD) is one of the main phytocannabinoids found in Cannabis sativa. In contrast to Δ9-tetrahydrocannabinol, it has a low affinity for cannabinoid receptors CB1 and CB2, thereby it does not induce significant psychoactive effects. However, CBD may interact with other receptors, including peroxisome proliferator-activated receptor gamma (PPARγ). CBD is a PPARγ agonist and changes its expression. There is considerable evidence that CBD's effects are mediated by its interaction with PPARγ. So, we reviewed studies related to the interaction of CBD and PPARγ.

METHODS

In this comprehensive literature review, the term 'cannabidiol' was used in combination with the following keywords including 'PPARγ', 'Alzheimer's disease', 'Parkinson's disease', 'seizure', 'multiple sclerosis', 'immune system', 'cardiovascular system', 'cancer', and 'adipogenesis'. PubMed, Web of Science, and Google Scholar were searched until December 20, 2022. A total of 78 articles were used for the reviewing process.

RESULTS

CBD, via activation of PPARγ, promotes significant pharmacological effects. The present review shows that the effects of CBD on Alzheimer's disease and memory, Parkinson's disease and movement disorders, multiple sclerosis, anxiety and depression, cardiovascular system, immune system, cancer, and adipogenesis are mediated, at least in part, via PPARγ.

CONCLUSION

CBD not only activates PPARγ but also affects its expression in the body. It was suggested that the late effects of CBD are mediated via PPARγ activation. We suggested that CBD's chemical structure is a good backbone for developing new dual agonists. Combining it with other chemicals enhances their biological effectiveness while reducing their dosage. The present study indicated that PPARγ is a key target for CBD, and its activation by CBD should be considered in all future studies.

Differences in intracellular protein levels in monocytes and CD4+ lymphocytes between bipolar depressed patients and healthy controls: A pilot study with tyramine-based signal-amplified flow cytometry

BACKGROUND

Molecular biomarkers for bipolar disorder (BD) that distinguish it from other manifestations of depressive symptoms remain unknown. The aim of this study was to determine if a very sensitive tyramine-based signal-amplification technology for flow cytometry (CellPrint™) could facilitate the identification of cell-specific analyte expression profiles of peripheral blood cells for bipolar depression (BPD) versus healthy controls (HCs).

METHODS

The diagnosis of psychiatric disorders was ascertained with Mini International Neuropsychiatric Interview for DSM-5. Expression levels for eighteen protein analytes previously shown to be related to bipolar disorder were assessed with CellPrint™ in CD4⁺ T cells and monocytes of bipolar patients and HCs. Implementation of protein-protein interaction (PPI) network and pathway analysis was subsequently used to identify new analytes and pathways for subsequent interrogations.

RESULTS

Fourteen drug-naïve or -free patients with bipolar I or II depression and 17 healthy controls (HCs) were enrolled. The most distinguishable changes in analyte expression based on t-tests included GSK3β, HMGB1, IRS2, phospho-GSK3αβ, phospho-RELA, and TSPO in CD4⁺ T cells and calmodulin, GSK3β, IRS2, and phospho-HS1 in monocytes. Subsequent PPI and pathway analysis indicated that prolactin, leptin, BDNF, and interleukin-3 signal pathways were significantly different between bipolar patients and HCs.

LIMITATION

The sample size of the study was small and 2 patients were on medications.

CONCLUSION

In this pilot study, CellPrint™ was able to detect differences in cell-specific protein levels between BPD patients and HCs. A subsequent study including samples from patients with BPD, major depressive disorder, and HCs is warranted.

Targeting Underlying Inflammation in Carcinoma Is Essential for the Resolution of Depressiveness

In modern clinical practice and research on behavioral changes in patients with oncological problems, there are several one-sided approaches to these problems. Strategies for early detection of behavioral changes are considered, but they must take into account the specifics of the localization and phase in the course and treatment of somatic oncological disease. Behavioral changes, in particular, may correlate with systemic proinflammatory changes. In the up-to-date literature, there are a lot of useful pointers on the relationship between carcinoma and inflammation and between depression and inflammation. This review is intended to provide an overview of these similar underlying inflammatory disturbances in both oncological disease and depression. The specificities of acute and chronic inflammation are considered as a basis for causal current and future therapies. Modern therapeutic oncology protocols may also cause transient behavioral changes, so assessment of the quality, quantity, and duration of behavioral symptoms is necessary to prescribe adequate therapy. Conversely, antidepressant properties could be used to ameliorate inflammation. We will attempt to provide some impetus and present some unconventional potential treatment targets related to inflammation. It is certain that only an integrative oncology approach is justifiable in modern patient treatment.

The Impact of Posttraumatic Stress Disorder on Pharmacologic Intervention Outcomes for Adults With Bipolar Disorder: A Systematic Review

BACKGROUND

The prevalence of posttraumatic stress disorder (PTSD) co-occurring in people with bipolar disorder (BD) is high. People with BD and PTSD may experience different outcomes and quality of life after pharmacologic treatment than those with BD alone. This review systematically explores the impact of PTSD on pharmacologic treatment outcomes for adults with BD.

METHODS

We conducted a systematic search up to November 25, 2021, using MEDLINE Complete, Embase, American Psychological Association PsycInfo, and the Cochrane Central Register of Controlled Trials to identify randomized and nonrandomized studies of pharmacologic interventions for adults with BD that assessed for comorbid PTSD. We used the Newcastle-Ottawa Scale and Cochrane Risk of Bias tool to assess the risk of bias.

RESULTS

The search identified 5093 articles, and we reviewed 62 full-text articles. Two articles met inclusion criteria (N = 438). One article was an observational study, and the other was a randomized comparative effectiveness trial. The observational study examined lithium response rates and found higher response rates in BD alone compared with BD plus PTSD over 4 years. The randomized trial reported more severe symptoms in the BD plus PTSD group than in those with BD alone following 6 months of quetiapine treatment. There was no significant difference in the lithium treatment group at follow-up.

CONCLUSIONS

Comorbid PTSD may affect quetiapine and lithium treatment response in those with BD. Because of the high risk of bias and low quality of evidence, however, these results are preliminary. Specific studies exploring comorbid BD and PTSD are required to inform pharmacotherapy selection and guidelines appropriately. (International Prospective Register of Systematic Reviews ID: CRD42020182540).

The Strategy of Targeting Peroxisome Proliferator-Activated Receptor (PPAR) in the Treatment of Neuropsychiatric Disorders

Peroxisome proliferator-activated receptors (PPARs) are nonsteroid nuclear receptors and transcription factors that regulate several neuroinflammatory and metabolic processes, recently involved in several neuropsychiatric conditions, including Alzheimer's disease, Parkinson's disease, major depressive disorder, post-traumatic stress disorder (PTSD), schizophrenia spectrum disorders, and autism spectrum disorders. PPARs are ligand-activated receptors that, following stimulation, induce neuroprotective effects by decreasing neuroinflammatory processes through inhibition of the nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB) expression and consequent suppression of pro-inflammatory cytokine production. PPARs heterodimerize with the retinoid X-receptor (RXR) and bind to PPAR-responsive regulatory elements (PPRE) in the promoter region of target genes involved in lipid metabolism, synthesis of cholesterol, catabolism of amino acids, and inflammation. Interestingly, PPARs are considered functionally part of the extended endocannabinoid (eCB) system that includes the classic eCB, anandamide, which act at cannabinoid receptor types 1 (CB1) and 2 (CB2) and are implicated in the pathophysiology of stress-related neuropsychiatric disorders. In preclinical studies, PPAR stimulation improves anxiety and depression-like behaviors by enhancing neurosteroid biosynthesis. The peculiar functional role of PPARs by exerting anti-inflammatory and neuroprotective effects and their expression localization in neurons and glial cells of corticolimbic circuits make them particularly interesting as novel therapeutic targets for several neuropsychiatric disorders characterized by underlying neuroinflammatory/neurodegenerative mechanisms. Herein, we discuss the pathological hallmarks of neuropsychiatric conditions associated with neuroinflammation, as well as the pivotal role of PPARs with a special emphasis on the subtype alpha (PPAR-α) as a suitable molecular target for therapeutic interventions.

Obsessive-Compulsive Disorder and Metabolic Disorders: Overview and Future Perspective

Obsessive-compulsive disorder (OCD) has a bidirectional relationship with metabolic disorders. The purposes of this review are to decipher the links between OCD and metabolic disorders and to explore the etiological mechanism of OCD in metabolism, which may aid in early identification of and tailored interventions for OCD and metabolic disorders.

Are the antidepressant effects of insulin-sensitizing medications related to improvements in metabolic markers?

Insulin-sensitizing medications were originally used in psychiatric practice to treat weight gain and other metabolic side effects that accompany the use of mood stabilizers, antipsychotics, and some antidepressants. However, in recent studies these medications have been shown to cause improvement in depressive symptoms, creating a potential new indication outside of metabolic regulation. However, it is still unclear whether the antidepressant properties of these medications are associated with improvements in metabolic markers. We performed a systematic search of the literature following PRISMA guidelines of studies investigating antidepressant effects of insulin-sensitizing medications. We specifically focused on whether any improvements in depressive symptoms were connected to the improvement of metabolic dysfunction. Majority of the studies included in this review reported significant improvement in depressive symptoms following treatment with insulin-sensitizing medications. Nine out of the fifteen included studies assessed for a correlation between improvement in symptoms and changes in metabolic markers and only two of the nine studies found such association, with effect sizes ranging from R² = 0.26-0.38. The metabolic variables, which correlated with improvements in depressive symptoms included oral glucose tolerance test, fasting plasma glucose and glycosylated hemoglobin following treatment with pioglitazone or metformin. The use of insulin-sensitizing medications has a clear positive impact on depressive symptoms. However, it seems that the symptom improvement may be unrelated to improvement in metabolic markers or weight. It is unclear which additional mechanisms play a role in the observed clinical improvement. Some alternative options include inflammatory, neuroinflammatory changes, improvements in cognitive functioning or brain structure. Future studies of insulin-sensitizing medications should measure metabolic markers and study the links between changes in metabolic markers and changes in depression. Additionally, it is important to use novel outcomes in these studies, such as changes in cognitive functioning and to investigate not only acute, but also prophylactic treatment effects.

Diabetes and mood disorders: shared mechanisms and therapeutic opportunities

OBJECTIVE

The objective of this manuscript is to provide a comprehensive and critical overview of the current evidence on the association between Diabetes mellitus (DM) and mood disorders [i.e., Major depressive disorder (MDD) and bipolar disorder (BD)], and therapeutic opportunities.

METHODS

We searched in MEDLINE (via Ovid) for placebo-controlled clinical trials published in the last 20 years that assessed drug repurposing approaches for the treatment of DM or mood disorders.

RESULTS

We found seven studies that aimed to verify the effects of antidepressants in patients diagnosed with DM, and eight studies that tested the effect of antidiabetic drugs in patients diagnosed with MDD or BD. Most studies published in the last two decades did not report a positive effect of antidepressants on glycemic control in patients with DM. On the other hand, antidiabetic drugs seem to have a positive effect on the treatment of MDD and BD.

CONCLUSIONS

While effect of antidepressants on glycemic control in patients with DM is still controversial, the use of antidiabetic drugs may be a promising strategy for patients with MDD or BD. Prospective studies are still needed.Key pointsMood disorders in patients with DM affect glycemic control, potentially increasing mortality risk.The effect of antidepressants on glycemic control in patients with DM is still controversial. The coexistence of complicated DM and a mood disorders would require a careful, individualised, and comprehensive evaluation.Insulin resistance may increase the risk of depressive symptoms and is associated with worse outcomes in BD.The use antidiabetic drugs may be a promising strategy for patients with MDD or BD. However, prospective trials are needed to prove a potential antidepressant activity of antidiabetic drugs.

Role of JAK-STAT and PPAR-Gamma Signalling Modulators in the Prevention of Autism and Neurological Dysfunctions

The Janus-kinase (JAK) and signal transducer activator of transcription (STAT) signalling pathways regulate gene expression and control various factors involved in normal physiological functions such as cell proliferation, neuronal development, and cell survival. JAK activation phosphorylates STAT3 in astrocytes and microglia, and this phosphorylation has been linked to mitochondrial damage, apoptosis, neuroinflammation, reactive astrogliosis, and genetic mutations. As a regulator, peroxisome proliferator-activated receptor gamma (PPAR-gamma), in relation to JAK-STAT signalling, prevents this phosphorylation and aids in the treatment of the above-mentioned neurocomplications. Changes in cellular signalling may also contribute to the onset and progression of autism. Thus, PPAR-gamma agonist upregulation may be associated with JAK-STAT signal transduction downregulation. It may also be responsible for attenuating neuropathological changes by stimulating SOCS3 or involving RXR or SMRT, thereby reducing transcription of the various cytokine proteins and genes involved in neuronal damage. Along with JAK-STAT inhibitors, PPAR-gamma agonists could be used as target therapeutic interventions for autism. This research-based review explores the potential involvement and mutual regulation of JAK-STAT and PPAR-gamma signalling in controlling multiple pathological factors associated with autism.

Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) Levels in Adolescent with Bipolar Disorder and Their Relationship with Metabolic Parameters

Peroxisome proliferator-activated receptor gamma (PPARγ) is one of the immune and metabolic regulatory agents. This study examined the serum PPARγ levels and metabolic syndrome (MetS) parameters in pediatric bipolar disorder (PBD) adolescents and compared them with healthy subjects. Serum PPARγ levels, fasting blood glucose (FBG), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), and fasting insulin levels of 39 PBD-type I (age range: 14-18) and 36 age- and sex-matched healthy control subjects were compared. The anthropometric measurements were also analyzed, including body weight, height, body mass index (BMI), waist circumference (WC), and blood pressure measurements. The PPARγ levels were significantly lower, and the MetS prevalence was significantly higher in the PBD group than in the control group. The mean BMI, WC, serum TG, and FBG values of the PBD group were statistically higher than the healthy control group. There was no significant relationship between the PPARγ levels and metabolic parameters except fasting glucose. Lower PPARγ activity and higher MetS prevalence in PBD indicate dysregulation of immune and metabolic regulatory parameters. These results may shed light on developing new PBD medications.

Depression with atypical neurovegetative symptoms shares genetic predisposition with immuno-metabolic traits and alcohol consumption

BACKGROUND

Depression is a highly prevalent and heterogeneous disorder. This study aims to determine whether depression with atypical features shows different heritability and different degree of overlap with polygenic risk for psychiatric and immuno-metabolic traits than other depression subgroups.

METHODS

Data included 30 069 European ancestry individuals from the UK Biobank who met criteria for lifetime major depression. Participants reporting both weight gain and hypersomnia were classified as ↑WS depression (N = 1854) and the others as non-↑WS depression (N = 28 215). Cases with non-↑WS depression were further classified as ↓WS depression (i.e. weight loss and insomnia; N = 10 142). Polygenic risk scores (PRS) for 22 traits were generated using genome-wide summary statistics (Bonferroni corrected p = 2.1 × 10-4). Single-nucleotide polymorphism (SNP)-based heritability of depression subgroups was estimated.

RESULTS

↑WS depression had a higher polygenic risk for BMI [OR = 1.20 (1.15-1.26), p = 2.37 × 10-14] and C-reactive protein [OR = 1.11 (1.06-1.17), p = 8.86 × 10-06] v. non-↑WS depression and ↓WS depression. Leptin PRS was close to the significance threshold (p = 2.99 × 10-04), but the effect disappeared when considering GWAS summary statistics of leptin adjusted for BMI. PRS for daily alcohol use was inversely associated with ↑WS depression [OR = 0.88 (0.83-0.93), p = 1.04 × 10-05] v. non-↑WS depression. SNP-based heritability was not significantly different between ↑WS depression and ↓WS depression (14.3% and 12.2%, respectively).

CONCLUSIONS

↑WS depression shows evidence of distinct genetic predisposition to immune-metabolic traits and alcohol consumption. These genetic signals suggest that biological targets including immune-cardio-metabolic pathways may be relevant to therapies in individuals with ↑WS depression.

New Insights Into the Pivotal Role of CREB-Regulated Transcription Coactivator 1 in Depression and Comorbid Obesity

Depression and obesity are major public health concerns, and there is mounting evidence that they share etiopathophysiological mechanisms. The neurobiological pathways involved in both mood and energy balance regulation are complex, multifactorial and still incompletely understood. As a coactivator of the pleiotropic transcription factor cAMP response element-binding protein (CREB), CREB-regulated transcription coactivator 1 (CRTC1) has recently emerged as a novel regulator of neuronal plasticity and brain functions, while CRTC1 dysfunction has been associated with neurodegenerative and psychiatric diseases. This review focuses on recent evidence emphasizing the critical role of CRTC1 in the neurobiology of depression and comorbid obesity. We discuss the role of CRTC1 downregulation in mediating chronic stress-induced depressive-like behaviors, and antidepressant response in the light of the previously characterized Crtc1 knockout mouse model of depression. The putative role of CRTC1 in the alteration of brain energy homeostasis observed in depression is also discussed. Finally, we highlight rodent and human studies supporting the critical involvement of CRTC1 in depression-associated obesity.

Inflammatory markers, brain-derived neurotrophic factor, and the symptomatic course of adolescent bipolar disorder: A prospective repeated-measures study

BACKGROUND

Numerous studies have found elevated pro-inflammatory markers and reduced brain-derived neurotrophic factor (BDNF) during symptomatic episodes of bipolar disorder (BD) in adults. There is a paucity of research examining these markers in youth with BD, or longitudinally in any BD age group.

METHODS

79 adolescents, ages 13-19 years, were enrolled, including 43 symptomatic adolescents with BD and 36 age-matched healthy controls (HC). Blood samples were collected from all participants at intake, and repeatedly from BD participants at pre-specified intervals over the course of two years. Serum was assayed for levels of pro-inflammatory markers (c-reactive protein [CRP], interleukin [IL]-6, tumor necrosis factor alpha [TNF-α]), BDNF and the anti-inflammatory marker, IL-10. Week-by-week severity of mood symptoms was assessed using semi-structured interviews.

RESULTS

Adolescents with BD provided an average of 4.6 blood samples, on average every 5.0 months. During the most severe symptomatic interval (i.e., highest sum of mood symptom scores) among BD adolescents, levels of CRP (p = 0.01) and pro- to anti-inflammatory ratios (CRP/IL-10; p < 0.001 and IL-6/IL-10; p = 0.046) were significantly greater, and IL-10 levels (p = 0.004) were significantly lower, vs. HC. There were no differences between BD and HC in IL-6, TNF-α or BDNF. Within BD participants, higher BDNF (p = 0.01) and IL-10 levels (p = 0.001) significantly predicted greater burden of mood symptoms over the subsequent epoch. Moreover, higher CRP levels (p = 0.009) at intake predicted greater time to recovery from the index symptomatic episode.

CONCLUSIONS

In the first repeated-measures study on this topic in adolescents with BD, we found evidence that CRP, an inexpensive and ubiquitous blood test, may be useful in predicting the prospective course of BD symptoms. Future larger studies are warranted.

Deletion of Crtc1 leads to hippocampal neuroenergetic impairments associated with depressive-like behavior

Mood disorders (MD) are a major burden on society as their biology remains poorly understood, challenging both diagnosis and therapy. Among many observed biological dysfunctions, homeostatic dysregulation, such as metabolic syndrome (MeS), shows considerable comorbidity with MD. Recently, CREB-regulated transcription coactivator 1 (CRTC1), a regulator of brain metabolism, was proposed as a promising factor to understand this relationship. Searching for imaging biomarkers and associating them with pathophysiological mechanisms using preclinical models can provide significant insight into these complex psychiatric diseases and help the development of personalized healthcare. Here, we used neuroimaging technologies to show that deletion of Crtc1 in mice leads to an imaging fingerprint of hippocampal metabolic impairment related to depressive-like behavior. By identifying a deficiency in hippocampal glucose metabolism as the underlying molecular/physiological origin of the markers, we could assign an energy-boosting mood-stabilizing treatment, ebselen, which rescued behavior and neuroimaging markers. Finally, our results point toward the GABAergic system as a potential therapeutic target for behavioral dysfunctions related to metabolic disorders. This study provides new insights on Crtc1's and MeS's relationship to MD and establishes depression-related markers with clinical potential.

Astrocyte Bioenergetics and Major Psychiatric Disorders

Ongoing research continues to add new elements to the emerging picture of involvement of astrocyte energy metabolism in the pathophysiology of major psychiatric disorders, including schizophrenia, mood disorders, and addictions. This review outlines what is known about the energy metabolism in astrocytes, the most numerous cell type in the brain, and summarizes the recent work on how specific perturbations of astrocyte bioenergetics may contribute to the neuropsychiatric conditions. The role of astrocyte energy metabolism in mental health and disease is reviewed on the organism, organ, and cell level. Data arising from genomic, metabolomic, in vitro, and neurobehavioral studies is critically analyzed to suggest future directions in research and possible metabolism-focused therapeutic interventions.

Repurposing Peroxisome Proliferator-Activated Receptor Agonists in Neurological and Psychiatric Disorders

Common pathophysiological mechanisms have emerged for different neurological and neuropsychiatric conditions. In particular, mechanisms of oxidative stress, immuno-inflammation, and altered metabolic pathways converge and cause neuronal and non-neuronal maladaptative phenomena, which underlie multifaceted brain disorders. The peroxisome proliferator-activated receptors (PPARs) are nuclear receptors modulating, among others, anti-inflammatory and neuroprotective genes in diverse tissues. Both endogenous and synthetic PPAR agonists are approved treatments for metabolic and systemic disorders, such as diabetes, fatty liver disease, and dyslipidemia(s), showing high tolerability and safety profiles. Considering that some PPAR-acting drugs permeate through the blood-brain barrier, the possibility to extend their scope from the periphery to central nervous system has gained interest in recent years. Here, we review preclinical and clinical evidence that PPARs possibly exert a neuroprotective role, thereby providing a rationale for repurposing PPAR-targeting drugs to counteract several diseases affecting the central nervous system.

The PPARg System in Major Depression: Pathophysiologic and Therapeutic Implications

To an exceptional degree, and through multiple mechanisms, the PPARg system rapidly senses cellular stress, and functions in the CNS in glial cells, neurons, and cerebrovascular endothelial cell in multiple anti-inflammatory and neuroprotective ways. We now know that depression is associated with neurodegeneration in the subgenual prefrontal cortex and hippocampus, decreased neuroplasticity, and defective neurogenesis. Brain-derived neurotrophic factor (BDNF) is markedly depleted in these areas, and is thought to contribute to the neurodegeneration of the subgenual prefrontal cortex and the hippocampus. The PPARg system strongly increases BDNF levels and activity in these brain areas. The PPARg system promotes both neuroplasticity and neurogenesis, both via effects on BDNF, and through other mechanisms. Ample evidence exists that these brain areas transduce many of the cardinal features of depression, directly or through their projections to sites such as the amygdala and nucleus accumbens. Behaviorally, these include feelings of worthlessness, anxiety, dread of the future, and significant reductions in the capacity to anticipate and experience pleasure. Physiologically, these include activation of the CRH and noradrenergic system in brain and the sympathetic nervous system and hypothalamic-pituitary-adrenal axis in the periphery. Patients with depression are also insulin-resistant. The PPARg system influences each of these behavioral and physiological in ways that would ameliorate the manifestations of depressive illness. In addition to the cognitive and behavioral manifestations of depression, depressive illness is associated with the premature onsets of coronary artery disease, stroke, diabetes, and osteoporosis. As a consequence, patients with depressive illness lose approximately seven years of life. Inflammation and insulin resistance are two of the predominant processes that set into motion these somatic manifestations. PPARg agonists significantly ameliorate both pathological processes. In summary, PPARg augmentation can impact positively on multiple significant pathological processes in depression. These include loss of brain tissue, defective neuroplasticity and neurogenesis, widespread inflammation in the central nervous system and periphery, and insulin resistance. Thus, PPARg agonists could potentially have significant antidepressant effects.

Targeting Metabolic Dysfunction for the Treatment of Mood Disorders: Review of the Evidence

Major depressive disorder (MDD) and bipolar disorder (BD) are often chronic with many patients not responding to available treatments. As these mood disorders are frequently associated with metabolic dysfunction, there has been increased interest in novel treatments that would target metabolic pathways. The objectives of this scoping review were to synthesize evidence on the impact on mood symptoms of lipid lowering agents and anti-diabetics drugs, while also reviewing current knowledge on the association between mood disorders and dyslipidemia or hyperglycemia. We propose that metabolic dysfunction is prevalent in both MDD and BD and it may contribute to the development of these disorders through a variety of pathophysiological processes including inflammation, brain structural changes, hormonal alterations, neurotransmitter disruptions, alteration on brain cholesterol, central insulin resistance, and changes in gut microbiota. Current evidence is conflicting on the use of statins, polyunsaturated fatty acids, thiazolidinediones, glucagon-like peptide agonists, metformin, or insulin for the treatment of MDD and BD. Given the paucity of high-quality randomized controlled trials, additional studies are needed before any of these medications can be repurposed in routine clinical practice. Future trials need to enrich patient recruitment, include evaluations of mechanism of action, and explore differential effects on specific symptom domains such as anhedonia, suicidality, and cognition.

Pioglitazone rescues high-fat diet-induced depression-like phenotypes and hippocampal astrocytic deficits in mice

The prevalence of diabetes is rapidly increasing worldwide and is highly associated with the incidence of depression. Pioglitazone, a Peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist, is widely used for treating patients with type 2 diabetes. However, whether pioglitazone alleviates metabolic disorder-related depression and astrocytic deficits remains unclear. Here we showed that 12 weeks of high-fat diet (HFD) feeding (from 8- to 20-week-old) induced not only obesity and insulin resistance, but also depression-like behaviors in mice. Astrocytic activation, a sign closely associated with depression, was also evident in the ventral hippocampus. Four weeks of pioglitazone (10 or 20 mg/kg, daily, from 20- to 24-week-old) treatment alleviated the HFD-induced glucose-metabolic dysfunctions, upregulation of ventral hippocampal GFAP, reduction of the total process lengths and the number of branch points of the ventral hippocampal CA1 GFAP-immunoreactive astrocytes and depressive phenotypes but had no effect on anxiety-like behaviors or hippocampus-related learning and memory in mice. These findings suggest that pioglitazone could be a potential therapeutic agent for metabolic disorders and associated depression.

Impact of ibuprofen and peroxisome proliferator-activated receptor gamma on emotion-related neural activation: A randomized, placebo-controlled trial

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen have shown initial promise in producing antidepressant effects. This is perhaps due to these drugs being peroxisome proliferator-activated receptor gamma (PPARγ) agonists, in addition to their inhibition of cyclooxygenase enzymes. Some, albeit mixed, evidence suggests that PPARγ agonists have antidepressant effects in humans and animals. This double-blind, placebo-controlled, pharmacologic functional magnetic resonance imaging (ph-fMRI) study aimed to elucidate the impact of ibuprofen on emotion-related neural activity and determine whether observed effects were due to changes in PPARγ gene expression. Twenty healthy volunteers completed an emotional face matching task during three fMRI sessions, conducted one week apart. Placebo, 200 mg, or 600 mg ibuprofen was administered 1 h prior to each scan in a pseudo-randomized order. Peripheral blood mononuclear cells were collected at each session to isolate RNA for PPARγ gene expression. At the doses used, ibuprofen did not significantly change PPARγ gene expression. Ibuprofen dose was associated with decreased blood oxygen level-dependent (BOLD) activation in the dorsolateral prefrontal cortex and fusiform gyrus during emotional face processing (faces-shapes). Additionally, PPARγ gene expression was associated with increased BOLD activation in the insula and transverse and superior temporal gyri (faces-shapes). No interaction effects between ibuprofen dose and PPARγ gene expression on BOLD activation were observed. Thus, results suggest that ibuprofen and PPARγ may have independent effects on emotional neurocircuitry. Future studies are needed to further delineate the roles of ibuprofen and PPARγ in exerting antidepressant effects in healthy as well as clinical populations.

Inflammatory signaling mechanisms in bipolar disorder

Bipolar disorder is a decidedly heterogeneous and multifactorial disease, with a high individual and societal burden. While not all patients display overt markers of elevated inflammation, significant evidence suggests that aberrant immune signaling contributes to all stages of the disease, and likely explains the elevated rates of comorbid inflammatory illnesses seen in this population. While individual systems have been intensely studied and targeted, a relative paucity of attention has been given to the interconnecting role of inflammatory signals therein. This review presents an updated overview of some of the most prominent pathophysiologic mechanisms in bipolar disorder, from mitochondrial, endoplasmic reticular, and calcium homeostasis, to purinergic, kynurenic, and hormonal/neurotransmitter signaling, showing inflammation to act as a powerful nexus between these systems. Several areas with a high degree of mechanistic convergence within this paradigm are highlighted to present promising future targets for therapeutic development and screening.

Systems Pharmacology Approach and Experiment Evaluation Reveal Multidimensional Treatment Strategy of LiangXueJieDu Formula for Psoriasis

Clinical studies have demonstrated the anti-psoriatic effect of the LiangXueJieDu (LXJD) herbal formula. However, the systemic mechanism and the targets of the LXJD formula have not yet been elucidated. In the present study, a systems pharmacology approach, metabolomics, and experimental evaluation were employed. First, by systematic absorption-distribution-metabolism-excretion (ADME) analysis, 144 active compounds with satisfactory pharmacokinetic properties were identified from 12 herbs of LXJD formula using the TCMSP database. These active compounds could be linked to 125 target proteins involved in the pathological processes underlying psoriasis. Then, the networks constituting the active compounds, targets, and diseases were constructed to decipher the pharmacological actions of this formula, indicating its curative effects in psoriasis treatment and related complications. The psoriasis-related pathway comprising several regulatory modules demonstrated the synergistic mechanisms of LXJD formula. Furthermore, the therapeutic effect of LXJD formula was validated in a psoriasis-like mouse model. Consistent with the systems pharmacology analysis, LXJD formula ameliorated IMQ-induced psoriasis-like lesions in mice, inhibited keratinocyte proliferation, improved keratinocyte differentiation, and suppressed the infiltration of CD3+ T cells. Compared to the model group, LXJD formula treatment remarkably reduced the expression of inflammatory cytokines and factors, such as IL-1β, IL-6, TNF-α, Cox2, and inhibited the phosphorylation of p-P65, p-IқB, p-ERK, p-P38, p-PI3K, p-AKT, indicating that LXJD formula exerts its therapeutic effect by inhibiting the MAPK, PI3K/AKT, and NF-қB signaling pathways. The metabolic changes in the serum of psoriasis patients were evaluated by liquid chromatography coupled with orbitrap mass spectrometry (LC-MS). The LXJD formula improved two perturbed metabolic pathways of glycerophospholipid metabolism and steroid hormone biosynthesis. Overall, this study revealed the complicated anti-psoriatic mechanism of LXJD formula and also offered a reliable strategy to elucidate the complex therapeutic mechanism of this Chinese herbal formula in psoriasis from a holistic perspective.

Intracellular Signaling Cascades in Bipolar Disorder

Bipolar spectrum disorders carry a significant public health burden. Disproportionately high rates of suicide, incarceration, and comorbid medical conditions necessitate an extraordinary focus on understanding the intricacies of this disease. Elucidating granular, intracellular details seems to be a necessary preamble to advancing promising therapeutic opportunities. In this chapter, we review a wide range of intracellular mechanisms including mitochondrial energetics, calcium signaling, neuroinflammation, the microbiome, neurotransmitter metabolism, glycogen synthase kinase 3-beta (GSK3β), protein kinase C (PKC) and diacylglycerol (DAG), and neurotrophins (especially BDNF), as well as the glutamatergic, dopaminergic, purinergic, and neurohormonal systems. Owing to the relative lack of understanding and effective therapeutic options compared to the rest of the spectrum, special attention is paid in the chapter to the latest developments in bipolar depression. Likewise, from a therapeutic standpoint, special attention should be paid to the pervasive mechanistic actions of lithium as a means of amalgamating numerous, disparate cascades into a digestible cognitive topology.

Drug repositioning for treatment-resistant depression: Hypotheses from a pharmacogenomic study

About 20-30% of patients with major depressive disorder (MDD) develop treatment-resistant depression (TRD) and finding new effective treatments for TRD has been a challenge. This study aimed to identify new possible pharmacological options for TRD. Genes in pathways included in predictive models of TRD in a previous whole exome sequence study were compared with those coding for targets of drugs in any phase of development, nutraceuticals, proteins and peptides from Drug repurposing Hub, Drug-Gene Interaction database and DrugBank database. We tested if known gene targets were enriched in TRD-associated genes by a hypergeometric test. Compounds enriched in TRD-associated genes after false-discovery rate (FDR) correction were annotated and compared with those showing enrichment in genes associated with MDD in the last Psychiatric Genomics Consortium genome-wide association study. Among a total of 15,475 compounds, 542 were enriched in TRD-associated genes (FDR p < .05). Significant results included drugs which are currently used in TRD (e.g. lithium and ketamine), confirming the rationale of this approach. Interesting molecules included modulators of inflammation, renin-angiotensin system, proliferator-activated receptor agonists, glycogen synthase kinase 3 beta inhibitors and the rho associated kinase inhibitor fasudil. Nutraceuticals, mostly antioxidant polyphenols, were also identified. Drugs showing enrichment for TRD-associated genes had a higher probability of enrichment for MDD-associated genes compared to those having no TRD-genes enrichment (p = 6.21e-55). This study suggested new potential treatments for TRD using a in silico approach. These analyses are exploratory only but can contribute to the identification of drugs to study in future clinical trials.

Advances toward precision medicine for bipolar disorder: mechanisms & molecules

Given its chronicity, contribution to disability and morbidity, and prevalence of more than 2%, the effective treatment, and prevention of bipolar disorder represents an area of significant unmet medical need. While more than half a century has passed since the introduction of lithium into widespread use at the birth of modern psychopharmacology, that medication remains a mainstay for the acute treatment and prevention of recurrent mania/hypomania and depression that characterize bipolar disorder. However, the continued limited understanding of how lithium modulates affective behavior and lack of validated cellular and animal models have resulted in obstacles to discovering more effective mood stabilizers with fewer adverse side effects. In particular, while there has been progress in developing new pharmacotherapy for mania, developing effective treatments for acute bipolar depression remain inadequate. Recent large-scale human genetic studies have confirmed the complex, polygenic nature of the risk architecture of bipolar disorder, and its overlap with other major neuropsychiatric disorders. Such discoveries have begun to shed light on the pathophysiology of bipolar disorder. Coupled with broader advances in human neurobiology, neuropharmacology, noninvasive neuromodulation, and clinical trial design, we can envision novel therapeutic strategies informed by defined molecular mechanisms and neural circuits and targeted to the root cause of the pathophysiology. Here, we review recent advances toward the goal of better treatments for bipolar disorder, and we outline major challenges for the field of translational neuroscience that necessitate continued focus on fundamental research and discovery.

How to Utilize Clinical and Genetic Information for Personalized Treatment of Major Depressive Disorder: Step by Step Strategic Approach

Depression is the single largest contributor to non-fatal health loss and affects 322 million people globally. The clinical heterogeneity of this disorder shows biological correlates and it makes the personalization of antidepressant prescription an important pillar of treatment. There is increasing evidence of genetic overlap between depression, other psychiatric and non-psychiatric disorders, which varies across depression subtypes. Therefore, the first step of clinical evaluation should include a careful assessment of psychopathology and physical health, not limited to previously diagnosed disorders. In part of the patients indeed the pathogenesis of depression may be strictly linked to inflammatory and metabolic abnormalities, and the treatment should target these as much as the depressive symptoms themselves. When the evaluation of the symptom and drug tolerability profile, the concomitant biochemical abnormalities and physical conditions is not enough and at least one pharmacotherapy failed, the genotyping of variants in CYP2D6/CYP2C19 (cytochromes responsible for antidepressant metabolism) should be considered. Individuals with altered metabolism through one of these enzymes may benefit from some antidepressants rather than others or need dose adjustments. Finally, if available, the polygenic predisposition towards cardio-metabolic disorders can be integrated with non-genetic risk factors to tune the identification of patients who should avoid medications associated with this type of side effects. A sufficient knowledge of the polygenic risk of complex medical and psychiatric conditions is becoming relevant as this information can be obtained through direct-to-consumer genetic tests and in the future it may provided by national health care systems.

Clinical Evidence of Antidepressant Effects of Insulin and Anti-Hyperglycemic Agents and Implications for the Pathophysiology of Depression-A Literature Review

Close connections between depression and type 2 diabetes (T2DM) have been suggested by many epidemiological and experimental studies. Disturbances in insulin sensitivity due to the disruption of various molecular pathways cause insulin resistance, which underpins many metabolic disorders, including diabetes, as well as depression. Several anti-hyperglycemic agents have demonstrated antidepressant properties in clinical trials, probably due to their action on brain targets based on the shared pathophysiology of depression and T2DM. In this article, we review reports of clinical trials examining the antidepressant effect of these medications, including insulin, metformin, glucagon like peptide-1 receptor agonists (GLP-1RA), and peroxisome proliferator-activated receptor (PPAR)-γ agonists, and briefly consider possible molecular mechanisms underlying the associations between amelioration of insulin resistance and improvement of depressive symptoms. In doing so, we intend to suggest an integrative perspective for understanding the pathophysiology of depression.

Comparative efficacy and tolerability of pharmacological treatments for the treatment of acute bipolar depression: A systematic review and network meta-analysis

OBJECTIVE

We investigated the comparative efficacy and tolerability of pharmacological treatment strategies for the treatment of acute bipolar depression.

DATA SOURCES

A systematic review and network meta-analysis was conducted by searching eight registries for published and unpublished, double-blind, randomized controlled trials of pharmacotherapies for the acute treatment of bipolar depression.

DATA EXTRACTION AND SYNTHESIS

PRISMA guidelines were used for abstracting data, while the Cochrane Risk of Bias Tool was used to assess data quality. Data extraction was done independently by two reviewers, with discrepancies resolved by consensus. Data were pooled using a random-effects model.

MAIN OUTCOMES AND MEASURES

Primary outcomes were efficacy (response and remission rate) and acceptability (completion of treatment and dropouts due to adverse events). Summary odds ratios (ORs) were estimated using pairwise and network meta-analysis with random effects.

RESULTS

Identified citations (4,404) included 50 trials comprising 11,448 participants. Escitalopram, phenelzine, moclobemide, carbamazepine, sertraline, lithium, paroxetine, aripiprazole, gabapentin and ziprasidone appear to be ineffective as compared to placebo in treatment of bipolar depression. Divalproex, olanzapine/fluoxetine, olanzapine, quetiapine, cariprazine, and lamotrigine, appear to be effective as compared to placebo in treatment of bipolar depression according to the network meta-analysis. Aripiprazole showed higher discontinuation rates versus placebo due to the appearance of any adverse event. Quetiapine was better than placebo at reducing treatment-emergent affective switches. For Bipolar I Disorder, cariprazine, fluoxetine, imipramine, lamotrigine, lurasidone, olanzapine-fluoxetine, and olanzapine were significantly better than placebo at response, while fluoxetine, imipramine, cariprazine, lurasidone, olanzapine-fluoxetine, and olanzapine were significantly better than placebo at remission.

CONCLUSIONS AND RELEVANCE

These results could serve evidence-based practice and inform patients, physicians, guideline developers, and policymakers on the relative benefits of the different antidepressants, antipsychotics, and mood-stabilizing agents for the treatment of bipolar depression.

REGISTRATION

PROSPERO (CRD42019122172).

The Novel Role of PPAR Alpha in the Brain: Promising Target in Therapy of Alzheimer's Disease and Other Neurodegenerative Disorders

Peroxisome proliferator activated receptor alpha (PPAR-α) belongs to the family of ligand-regulated nuclear receptors (PPARs). These receptors after heterodimerization with retinoid X receptor (RXR) bind in promotor of target genes to PPAR response elements (PPREs) and act as a potent transcription factors. PPAR-α and other receptors from this family, such as PPAR-β/δ and PPAR-γ are expressed in the brain and other organs and play a significant role in oxidative stress, energy homeostasis, mitochondrial fatty acids metabolism and inflammation. PPAR-α takes part in regulation of genes coding proteins that are involved in glutamate homeostasis and cholinergic/dopaminergic signaling in the brain. Moreover, PPAR-α regulates expression of genes coding enzymes engaged in amyloid precursor protein (APP) metabolism. It activates gene coding of α secretase, which is responsible for non-amyloidogenic pathway of APP degradation. It also down regulates β secretase (BACE-1), the main enzyme responsible for amyloid beta (Aβ) peptide release in Alzheimer Diseases (AD). In AD brain expression of genes of PPAR-α and PPAR-γ coactivator-1 alpha (PGC-1α) is significantly decreased. PPARs are altered not only in AD but in other neurodegenerative/neurodevelopmental and psychiatric disorder. PPAR-α downregulation may decrease anti-oxidative and anti-inflammatory processes and could be responsible for the alteration of fatty acid transport, lipid metabolism and disturbances of mitochondria function in the brain of AD patients. Specific activators of PPAR-α may be important for improvement of brain cells metabolism and cognitive function in neurodegenerative and neurodevelopmental disorders.

Is There a Future for PPARs in the Treatment of Neuropsychiatric Disorders?

Recently, peroxisome proliferator-activated receptor (PPAR)-α and γ isoforms have been gaining consistent interest in neuropathology and treatment of neuropsychiatric disorders. Several studies have provided evidence that either the receptor expression or the levels of their endogenously-produced modulators are downregulated in several neurological and psychiatric disorders and in their respective animal models. Remarkably, administration of these endogenous or synthetic ligands improves mood and cognition, suggesting that PPARs may offer a significant pharmacological target to improve several neuropathologies. Furthermore, various neurological and psychiatric disorders reflect sustained levels of systemic inflammation. Hence, the strategy of targeting PPARs for their anti-inflammatory role to improve these disorders is attracting attention. Traditionally, classical antidepressants fail to be effective, specifically in patients with inflammation. Non-steroidal anti-inflammatory drugs exert potent antidepressant effects by acting along with PPARs, thereby strongly substantiating the involvement of these receptors in the mechanisms that lead to development of several neuropathologies. We reviewed running findings in support of a role for PPARs in the treatment of neurological diseases, including Alzheimer's disease or psychiatric disorders, such as major depression. We discuss the opportunity of targeting PPARs as a future pharmacological approach to decrease neuropsychiatric symptoms at the same time that PPAR ligands resolve neuroinflammatory processes.

Variants in the Upstream Region of the Insulin Receptor Substrate-1 Gene Is Associated with Major Depressive Disorder in the Han Chinese Population

INTRODUCTION

Major depressive disorder (MDD) is one of the most prevalent and disabling mental disorders, although its underlying genetic mechanism remains unknown. Insulin receptor substrate-1 (IRS-1) is one of the critical downstream molecules in the insulin resistance signaling pathway, linking depression and diabetes. Therefore, we hypothesized that IRS-1 would be a susceptible gene for MDD, and we aimed to examine the genetic association between IRS-1 and MDD.

METHODS

This case-control study included 583 patients with MDD and 564 controls, and the genotypic and allelic distributions of the IRS-1 gene's four single nucleotide polymorphisms (SNPs) were detected by TaqMan SNP genotyping technology. Of the 583 patients, 191 underwent a further detailed interview about symptom severity and family history of mental illness. The chi-square or t test was used to analyze the data, and analyses were performed using SPSS19.0 software.

RESULTS

A haplotype in the 5'-upstream region of IRS-1 consisting of rs13411764 and rs3820926 was a risk factor of MDD. Patients with a family history of mental illness were more likely to have a GG genotype in rs13411764 and a G-T haplotype containing rs13411714-rs3820926.

DISCUSSION

The findings imply that the haplotype consisting of rs13411764 and rs3820926 in the upstream of IRS-1 is a risk factor for MDD. This haplotype could affect IRS-1 expression levels, and it is mostly inherited from parents. Thus, the presence of variants in the upstream region of IRS-1 is a risk factor of MDD, and this study could serve as a convincing reference for further studies.

Stress-Induced Epigenetic Changes in Hippocampal Mkp-1 Promote Persistent Depressive Behaviors

Chronic stress induces persistent depressive behaviors. Stress-induced transcriptional alteration over the homeostatic range in stress hormone-sensitive brain regions is believed to underlie long-lasting depressive behaviors. However, the detailed mechanisms by which chronic stress causes those adaptive changes are not clearly understood. In the present study, we investigated whether epigenetic changes regulate stress-induced depressive behaviors. We found that chronic stress in mice downregulates the epigenetic factors HDAC2 and SUV39H1 in the hippocampus. A series of follow-up analyses including ChIP assay and siRNA-mediated functional analyses reveal that glucocorticoids released by stress cumulatively increase Mkp-1 expression in the hippocampus, and increased Mkp-1 then debilitates p-CREB and PPARγ, which in turn suppress the epigenetic factors HDAC2 and SUV39H1. Furthermore, HDAC2 and SUV39H1 normally suppress the transcription of the Mkp-1, and therefore the reduced expression of HDAC2 and SUV39H1 increases Mkp-1 expression. Accordingly, repeated stress progressively strengthens a vicious cycle of the Mkp-1 signaling cascade that facilitates depressive behaviors. These results suggest that the hippocampal stress adaptation system comprising HDAC2/SUV39H1-regulated Mkp-1 signaling network determines the vulnerability to chronic stress and the maintenance of depressive behaviors.

Beyond evidence-based treatment of bipolar disorder: Rational pragmatic approaches to management

The evidence for efficacy of many currently available treatments for bipolar disorder is based on studies of nonrefractory patients with bipolar disorder. Therefore, not surprisingly, most treatment recommendations and guidelines for the treatment of bipolar disorder and its many comorbidities depend heavily on data from placebo controlled randomized clinical trials (RCTs), but these RCTs provide little direction for the clinician as to what next steps might be optimal in non- or partial-responders and in those with ongoing medical and psychiatric comorbidities. Given this and the paucity of RCTs at later treatment junctures, we thought it appropriate to begin a discussion of the quality of the data that some experts in the field might consider using in choosing and sequencing drugs and their combination. We acknowledge that many other clinical investigators may prefer very different sequences, but thought the suggestions offered here might be useful to some clinicians in the field, might start discussions of other options in the literature, and, at the same time, provide a preliminary outline for a new round of much-needed clinical trials to better inform clinical practice. Given the very wide range of the quality of the data and clinical principles on which the current suggestions are based, only minimal references are included and a comprehensive review of the literature supporting each option would be outside the scope of this manuscript.

Exploration and Development of PPAR Modulators in Health and Disease: An Update of Clinical Evidence

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors that govern the expression of genes responsible for energy metabolism, cellular development, and differentiation. Their crucial biological roles dictate the significance of PPAR-targeting synthetic ligands in medical research and drug discovery. Clinical implications of PPAR agonists span across a wide range of health conditions, including metabolic diseases, chronic inflammatory diseases, infections, autoimmune diseases, neurological and psychiatric disorders, and malignancies. In this review we aim to consolidate existing clinical evidence of PPAR modulators, highlighting their clinical prospects and challenges. Findings from clinical trials revealed that different agonists of the same PPAR subtype could present different safety profiles and clinical outcomes in a disease-dependent manner. Pemafibrate, due to its high selectivity, is likely to replace other PPARα agonists for dyslipidemia and cardiovascular diseases. PPARγ agonist pioglitazone showed tremendous promises in many non-metabolic disorders like chronic kidney disease, depression, inflammation, and autoimmune diseases. The clinical niche of PPARβ/δ agonists is less well-explored. Interestingly, dual- or pan-PPAR agonists, namely chiglitazar, saroglitazar, elafibranor, and lanifibranor, are gaining momentum with their optimistic outcomes in many diseases including type 2 diabetes, dyslipidemia, non-alcoholic fatty liver disease, and primary biliary cholangitis. Notably, the preclinical and clinical development for PPAR antagonists remains unacceptably deficient. We anticipate the future design of better PPAR modulators with minimal off-target effects, high selectivity, superior bioavailability, and pharmacokinetics. This will open new possibilities for PPAR ligands in medicine.

Targeting the immune system in the treatment of bipolar disorder

RATIONALE

Immune dysfunction has been strongly implicated in the pathophysiology of bipolar disorder (BD). As such, numerous clinical trials have investigated the effects of anti-inflammatory agents in the treatment of BD.

OBJECTIVES

Review clinical studies evaluating the effects of anti-inflammatory agents in the treatment of BD during all illness phases (e.g., depression, mania, and euthymia).

METHODS

Relevant databases were searched from inception to August 27, 2018 for clinical studies evaluating the effects of anti-inflammatory agents in BD.

RESULTS

The majority of identified clinical trials evaluated adjunctive anti-inflammatory agents in the acute treatment of bipolar depression, demonstrating antidepressant effects with N-acetylcysteine (NAC), pioglitazone, minocycline, and coenzyme Q10, along with mixed evidence for omega-3s, and non-steroidal anti-inflammatory drugs (NSAIDs). The anti-manic effects of adjunctive anti-inflammatory agents have been minimally studied, with some promising preliminary results supporting potential anti-manic effects of adjunctive celecoxib and NAC. Maintenance studies are also limited, with inadequate evidence to support mood stabilizing effects of anti-inflammatories while euthymic. Regardless of illness phase, early results suggest that anti-inflammatory agents are likely most beneficial in the subgroup of BD with immune dysregulation.

CONCLUSIONS

Several proof-of-concept clinical trials have shown promising results for anti-inflammatory agents in the treatment of bipolar depression with moderate effect sizes and good tolerability. The effects of anti-inflammatory agents during manic and euthymic periods remains uncertain. Future larger studies, using stratified samples, enriched for participants with immune dysfunction, are required to determine the role of immune modulating agents in the treatment of BD.

Insulin resistance takes center stage: a new paradigm in the progression of bipolar disorder

Bipolar Disorder (BD) is a major psychiatric illness affecting up to 5% of the population. BD can progress over time to a chronic "neuroprogressive" course with cognitive and functional impairment. Currently, there are no validated predictors indicating which patients will develop a neuroprogressive course and there are no specific treatments. This review presents data supporting a novel hypothesis on the mechanisms underlying bipolar neuroprogression. Insulin resistance (IR) is present in 52% of BD patients and is associated with chronic course, treatment nonresponse, adverse brain changes and cognitive impairment. Further, bipolar morbidity increases 12-fold following the onset of IR indicating that IR may modify disease progression. I review evidence that IR is a testable and treatable modifying factor in neuroprogression and that reversing IR may be an efficient (and perhaps the only) means of obtaining remission in some patients. I draw a parallel with Helicobacter pylori in peptic ulcer disease (a novel mechanism that brought together two previously unrelated phenomena that uncovered a new treatment approach). This model of bipolar progression combines shared dysregulated mechanisms between IR and BD, allowing for early screening, case finding, and monitoring for neuroprogression, with the potential for intervention that could prevent advanced bipolar illness. KEY MESSAGES Neuroprogression in bipolar disorder is defined by a more severe form of illness and poor outcome. Currently, there are no validated predictors of neuroprogression, which could help inform treatment and improve prognosis. Insulin resistance is present in more than half of all bipolar patients and is associated with a chronic course of illness, lack of response to mood stabilizing treatment, cognitive impairment and poor functional outcomes. Insulin resistance may modify the course of bipolar disorder and promote neuroprogression. Insulin resistance may be a testable and potentially modifiable risk factor for neuroprogression in bipolar disorder.

Impaired Glucose Metabolism in Bipolar Patients: The Role of Psychiatrists in Its Detection and Management

Bipolar patients have a higher risk of type 2 diabetes and obesity, which are associated with cardiovascular diseases as the leading cause of death in this group. Additionally, there is growing evidence that impaired glucose metabolism in bipolar patients is associated with rapid cycling, poor response to mood stabilizers and chronic course of illness. The aim of the study was to assess the prevalence of type 2 diabetes and other types of impaired glucose metabolism in bipolar patients along with an evaluation of the Fasting Triglycerides and Glucose Index (TyG) as a method of the insulin sensitivity assessment. The analysis of fasting glycemia, insulinemia and lipid profile in euthymic bipolar patients was performed, and the Homeostasis model assessment for insulin resistance (HOMA-IR) and TyG were computed. Type 2 diabetes was observed in 9% and insulin resistance with HOMA-IR in 48% of patients. The TyG and HOMA-IR indices were correlated (p < 0.0001), the TyG index value of 4.7 had the highest sensitivity and specificity for insulin resistance detection. The usefulness of TyG in the recognition of insulin resistance in bipolar patients was suggested. The significant role of psychiatrists in the detection and management of impaired glucose metabolism in bipolar patients was presented.

Neuroimmune nexus of depression and dementia: Shared mechanisms and therapeutic targets

Dysfunctional immune activity is a physiological component of both Alzheimer's disease (AD) and major depressive disorder (MDD). The extent to which altered immune activity influences the development of their respective cognitive symptoms and neuropathologies remains under investigation. It is evident, however, that immune activity affects neuronal function and circuit integrity. In both disorders, alterations are present in similar immune networks and neuroendocrine signalling pathways, immune responses persist in overlapping neuroanatomical locations, and morphological and structural irregularities are noted in similar domains. Epidemiological studies have also linked the two disorders, and their genetic and environmental risk factors intersect along immune-activating pathways and can be synonymous with one another. While each of these disorders individually contains a large degree of heterogeneity, their shared immunological components may link distinct phenotypes within each disorder. This review will therefore highlight the shared immune pathways of AD and MDD, their overlapping neuroanatomical features, and previously applied, as well as novel, approaches to pharmacologically manipulate immune pathways, in each neurological condition. LINKED ARTICLES: This article is part of a themed section on Therapeutics for Dementia and Alzheimer's Disease: New Directions for Precision Medicine. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.18/issuetoc.

Double-blind, placebo-controlled trial of pioglitazone for bipolar depression

BACKGROUND

Objective of the present study was to conduct an 8-week double-blind, randomized, placebo-controlled trial to test the efficacy of pioglitazone in the treatment of bipolar depression.

METHODS

38 outpatients with bipolar disorder and current major depressive episode were randomized to pioglitazone (15-45 mg/day) or placebo. The use of concomitant mood stabilizers, antipsychotics, and antidepressants was permitted. The primary outcome measure was the 30-item Inventory of Depressive Symptomatology, Clinician Rated (IDS-C30) total score change from baseline to endpoint. Laboratory evaluations, including serum level of inflammatory and metabolic biomarkers, were conducted.

RESULTS

37 subjects were analyzed for efficacy (1 subject had no follow-up data). Mean reduction from baseline to week 8 in IDS-C30 score was-6.59 for pioglitazone and -11.63 for placebo. Mixed effects modeling indicated borderline statistically significant difference between the two groups (p = 0.056) in favor of placebo. On analysis of inflammatory and metabolic markers, a statistically significant negative correlation was noted between change in leptin levels and change in depression scores in the pioglitazone group (r = -0.61, p = 0.047) but not in the placebo group, the significance of which is unclear as the study failed to demonstrate antidepressant efficacy of pioglitazone over placebo. No serious adverse effects were reported, and pioglitazone was well-tolerated.

LIMITATIONS

small sample size with inadequate power, concomitant use of other psychotropic medications, and lack of statistical adjustment for multiple testing.

CONCLUSION

Current study does not support the antidepressant efficacy of pioglitazone in the treatment of bipolar depression. (240 words).