PPARα Signaling: A Candidate Target in Psychiatric Disorder Management

Unveiling the role of astrogliosis in Alzheimer's disease Pathology: Insights into mechanisms and therapeutic approaches

Alzheimer's disease (AD) is one of the most debilitating age-related disorders that affect people globally. It impacts social and cognitive behavior of the individual and is characterized by phosphorylated tau and Aβ accumulation. Astrocytesmaintain a quiescent, anti-inflammatory state on anatomical level, expressing few cytokines and exhibit phagocytic activity to remove misfolded proteins. But in AD, in response to specific stimuli, astrocytes overstimulate their phagocytic character with overexpressing cytokine gene modules. Upon interaction with generated Aβ and neurofibrillary tangle, astrocytes that are continuously activated release a large number of inflammatory cytokines. This cytokine storm leads to neuroinflammation which is also one of the recognizable features of AD. Astrogliosis eventually promotes cholinergic dysfunction, calcium imbalance, oxidative stress and excitotoxicity. Furthermore, C5aR1, Lcn2/, BDNF/TrkB and PPARα/TFEB signaling dysregulation has a major impact on the disease progression. This review clarifies numerous ways that lead to astrogliosis, which is stimulated by a variety of processes that exacerbate AD pathology and make it a suitable target for AD treatment. Drugs under clinical and preclinical investigations that target several pathways managing astrogliosis and are efficacious in ameliorating the pathology of the disease are also included in this study. D-ALA2GIP, TRAM-34, Genistein, L-serine, MW150 and XPro1595 are examples of few drugs targeting astrogliosis. Therefore, this study may aid in the development of a potent therapeutic agent for ameliorating astrogliosis mediated AD progression.

Role of PPAR-Allopregnanolone Signaling in Behavioral and Inflammatory Gut-Brain Axis Communications

The gut microbiome regulates emotional behavior, stress responses, and inflammatory processes by communicating with the brain. How and which neurobiological mediators underlie this communication remain poorly understood. PPAR-α (peroxisome proliferator-activated receptor α), a transcription factor susceptible to epigenetic modifications, regulates pathophysiological functions, including metabolic syndrome, inflammation, and behavior. Mood disorders, inflammatory processes, and obesity are intertwined phenomena that are associated with low blood concentrations of the anti-inflammatory and "endogenous tranquilizer" neurosteroid allopregnanolone and poor PPAR-α function. Stress and consumption of obesogenic diets repress PPAR function in brain, enterocytes, lipocytes, and immune modulatory cells favoring inflammation, lipogenesis, and mood instability. Conversely, micronutrients and modulators of PPAR-α function improve microbiome composition, dampen systemic inflammation and lipogenesis, and improve anxiety and depression. In rodent stress models of anxiety and depression, PPAR activation normalizes both PPAR-α expression downregulation and decreased allopregnanolone content and ameliorates depressive-like behavior and fear responses. PPAR-α is known to regulate metabolic and inflammatory processes activated by short-chain fatty acids; endocannabinoids and congeners, such as N-palmitoylethanolamide, drugs that treat dyslipidemias; and micronutrients, including polyunsaturated fatty acids. Both PPAR-α and allopregnanolone are abundantly expressed in the colon, and they exert potent anti-inflammatory actions by blocking the toll-like receptor-4-nuclear factor-κB pathway in peripheral immune cells, neurons, and glia. The perspective that PPAR-α regulation in the colon by gut microbiota or metabolites influences central allopregnanolone content after trafficking to the brain, thereby serving as a mediator of gut-brain axis communications, is examined in this review.

The dopamine hypothesis of autism spectrum disorder: A comprehensive analysis of the evidence

Despite intensive research into the etiopathogenesis of autism spectrum disorder (ASD), limited progress has been achieved so far. Among the plethora of models seeking to clarify how ASD arises, a coherent dopaminergic model was lacking until recently. In 2017, we provided a theoretical framework that we designated "the dopamine hypothesis of ASD". In the meantime, numerous studies yielded empirical evidence for this model. 4 years later, we provided a second version encompassing a refined and reconceptualized framework that accounted for these novel findings. In this chapter, we will review the evidence backing the previous versions of our model and add the most recent developments to the picture. Along these lines, we intend to lay out a comprehensive analysis of the supporting evidence for the dopamine hypothesis of ASD.

Network pharmacology and topological analysis on tibolone metabolites and their molecular mechanisms in traumatic brain injury

Traumatic brain injury (TBI) is a pathology of great social impact, affecting millions of people worldwide. Despite the scientific advances to improve the management of TBI in recent years, we still do not have a specific treatment that controls the inflammatory process after mechanical trauma. The discovery and implementation of new treatments is a long and expensive process, making the repurpose of approved drugs for other pathologies a clinical interest. Tibolone is a drug in use for the treatment of symptoms associated with menopause and has been shown to have a broad spectrum of actions by regulating estrogen, androgen and progesterone receptors, whose activation exerts potent anti-inflammatory and antioxidant effects. In the present study, we aimed to investigate the therapeutic potential of the tibolone metabolites 3α-Hydroxytibolone, 3β-Hydroxytibolone, and Δ4-Tibolone as a possible therapy in TBI using network pharmacology and network topology analysis. Our results demonstrate that the estrogenic component mediated by the α and β metabolites can regulate synaptic transmission and cell metabolism, while the Δ metabolite may be involved in modulating the post-TBI inflammatory process. We identified several molecular targets, including KDR, ESR2, AR, NR3C1, PPARD, and PPARA, which are known to play critical roles in the pathogenesis of TBI. Tibolone metabolites were predicted to regulate the expression of key genes involved in oxidative stress, inflammation, and apoptosis. Overall, the repurposing of tibolone as a neuroprotective treatment for TBI holds promise for future clinical trials. However, further studies are needed to confirm its efficacy and safety in TBI patients.

VX-765 inhibits pyroptosis and reduces inflammation to prevent acute liver failure by upregulating PPARα expression

INTRODUCTION AND OBJECTIVES

As a fatal clinical syndrome, acute liver failure (ALF) is characterized by overwhelming liver inflammation and hepatic cell death. Finding new therapeutic methods has been a challenge in ALF research. VX-765 is a known pyroptosis inhibitor and has been reported to prevent damage in a variety of diseases by reducing inflammation. However, the role of VX-765 in ALF is still unclear.

MATERIALS AND METHODS

ALF model mice were treated with D-galactosamine (D-GalN) and lipopolysaccharide (LPS). LO2 cells were stimulated with LPS. Thirty subjects were enrolled in clinical experiments. The levels of inflammatory cytokines, pyroptosis-associated proteins and peroxisome proliferator-activated receptor α (PPARα) were detected using quantitative reverse transcription-polymerase chain reaction (qRT‒PCR), western blotting and immunohistochemistry. An automatic biochemical analyzer was used to determine the serum aminotransferase enzyme levels. Hematoxylin and eosin (HE) staining was used to observe the pathological features of the liver.

RESULTS

With the progression of ALF, the expression levels of interleukin (IL) -1β, IL-18, caspase-1, and serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were increased. VX-765 could reduce the mortality rate of ALF mice, relieve liver pathological damage, and reduce inflammatory responses to protect against ALF. Further experiments showed that VX-765 could protect against ALF through PPARα, and this protective effect against ALF was reduced in the context of PPARα inhibition.

CONCLUSIONS

As ALF progresses, inflammatory responses and pyroptosis deteriorate gradually. VX-765 can inhibit pyroptosis and reduce inflammatory responses to protect against ALF by upregulating PPARα expression, thus providing a possible therapeutic strategy for ALF.

Heterogeneity in major depressive disorder: The need for biomarker-based personalized treatments

Major Depressive Disorder (MDD) or depression is a pathological mental condition affecting millions of people worldwide. Identification of objective biological markers of depression can provide for a better diagnostic and intervention criteria; ultimately aiding to reduce its socioeconomic health burden. This review provides a comprehensive insight into the major biomarker candidates that have been implicated in depression neurobiology. The key biomarker categories are covered across all the "omics" levels. At the epigenomic level, DNA-methylation, non-coding RNA and histone-modifications have been discussed in relation to depression. The proteomics system shows great promise with inflammatory markers as well as growth factors and neurobiological alterations within the endocannabinoid system. Characteristic lipids implicated in depression together with the endocrine system are reviewed under the metabolomics section. The chapter also examines the novel biomarkers for depression that have been proposed by studies in the microbiome. Depression affects individuals differentially and explicit biomarkers identified by robust research criteria may pave the way for better diagnosis, intervention, treatment, and prediction of treatment response.

A Marked Low-Grade Inflammation and a Significant Deterioration in Metabolic Status in First-Episode Schizophrenia: A Five-Year Follow-Up Study

The objective of this study was to evaluate how schizophrenia spectrum disorders and applied long-term (5.1 years) antipsychotic (AP) treatment affect the serum level of acylcarnitines (ACs), cytokines and metabolic biomarkers and to characterize the dynamics of inflammatory and metabolic changes in the early course of the disorder. A total of 112 adults participated in the study (54 patients with first-episode psychosis (FEP) and 58 control subjects). Biomolecule profiles were measured at the onset of first-episode psychosis and 0.6 years and 5.1 years after the initiation of APs. The results of the present study confirmed that specific metabolic-inflammatory imbalance characterizes AP-naïve patients. Short-term (0.6-years) AP treatment has a favourable effect on psychotic symptoms, as well as the recovery of metabolic flexibility and resolution of low-level inflammation. However, 5.1 years of AP treatment resulted in weight gain and increased serum levels of interleukin (IL)-2, IL-4, IL-6, IL-10, interferon-γ, hexoses, acetylcarnitine, short-chain ACs (C3, C4) and long-chain ACs (C16:2, C18:1, C18:2). In conclusion, despite the improvement in psychotic symptoms, 5.1 years of AP treatment was accompanied by a pronounced metabolic-inflammatory imbalance, which was confirmed by the presence of enhanced pro-inflammatory activity and increased obesity with changes in the metabolism of carbohydrates, lipids, and their metabolites.