Anti-inflammatory actions of PPAR ligands: new insights on cellular and molecular mechanisms

Computer-Aided Drug Discovery for Undruggable Targets

Undruggable targets are those of therapeutical significance but challenging for conventional drug design approaches. Such targets often exhibit unique features, including highly dynamic structures, a lack of well-defined ligand-binding pockets, the presence of highly conserved active sites, and functional modulation by protein-protein interactions. Recent advances in computational simulations and artificial intelligence have revolutionized the drug design landscape, giving rise to innovative strategies for overcoming these obstacles. In this review, we highlight the latest progress in computational approaches for drug design against undruggable targets, present several successful case studies, and discuss remaining challenges and future directions. Special emphasis is placed on four primary target categories: intrinsically disordered proteins, protein allosteric regulation, protein-protein interactions, and protein degradation, along with discussion of emerging target types. We also examine how AI-driven methodologies have transformed the field, from applications in protein-ligand complex structure prediction and virtual screening to de novo ligand generation for undruggable targets. Integration of computational methods with experimental techniques is expected to bring further breakthroughs to overcome the hurdles of undruggable targets. As the field continues to evolve, these advancements hold great promise to expand the druggable space, offering new therapeutic opportunities for previously untreatable diseases.

Diverse Lenabasum pathway activation in dermatomyositis patients' blood

Lenabasum, a non-psychoactive cannabinoid type-2 receptor (CB2R) agonist, has shown promise in reducing cutaneous disease in Dermatomyositis (DM) patients. Lenabasum activates two distinct receptors: CB2R and the nuclear peroxisome proliferator-activated receptor-γ (PPARγ). Our goal was to investigate the dominant mechanism of action leading to pathogenic IFNβ reduction by lenabasum (through CB2R or PPARγ) across leukocytes. We utilized whole blood leukocytes from 14 DM patients and grouped patients as in vitro responders or non-responders. We stimulated leukocytes in vitro in the presence of CB2R and PPARγ inhibitors and lenabasum. Intracellular and extracellular marker expression was analyzed by flow cytometry. CD4+ T (p < 0.05), monocyte-derived dendritic cells (p = 0.06), and intermediate monocytes (iMs) (p < 0.05) activate a CB2R-mediated lenabasum pathway in responders. Responder B cells (p < 0.01), CD8+ T cells (p < 0.01), and non-classical monocytes (p = 0.06) activate a co-dependent CB2R/PPARγ-mediated lenabasum pathway. Lenabasum can independently activate CB2R or PPARγ in myeloid dendritic cells (p < 0.05). Responder plasmacytoid dendritic cells (p < 0.05) and classical monocytes (p < 0.01) activate a PPARγ-mediated lenabasum pathway. CB2R was increased in certain responder CB2R-mediated cell populations compared to non-responders. Lenabasum elevated cyclooxygenase-2 or 15-lipoxygenase-1 levels in all responder CB2R-mediated cell populations except iMs. Baseline cell-to-cell CB2R/PPARγ testing could be useful to select ideal lenabasum candidates.Trial Registration: Registered at ClinicalTrials.gov (Identifier: NCT03813160) on 2019-01-23. Sponsored by Corbus Pharmaceuticals Inc.

Fatty acid binding proteins and their involvement in anxiety and mood disorders

Anxiety and mood disorders represent the most prevalent neuropsychiatric conditions. Nevertheless, current pharmacotherapies often have a host of adverse side effects. Emerging evidence suggests modulation of lipid signaling pathways - particularly those involved in the endocannabinoid (eCB) system, may offer promising new targets for the treatment of anxiety and depression. Polyunsaturated fatty acids (PUFA) and their metabolic derivatives, including the eCB ligands, have garnered significant attention for their roles in neuropsychiatric disease mechanisms. Intracellular transportation of these lipids is facilitated by fatty acid binding proteins (FABP), which are increasingly recognized as key regulators of lipid signaling. Accumulating evidence indicates that FABPs may impact the development of neuropsychiatric disorders by mediating the signaling pathways of PUFAs and eCB ligands. In this review, we investigate the role of FABPs in two major categories of neuropsychiatric conditions - anxiety disorders and clinical depression. We begin by examining several neuropathophysiological mechanisms through which FABPs can impact these conditions, focusing on their role as lipid chaperones. These mechanisms include the trafficking of eCB ligands, as well as oleoylethanolamide and palmitoylethanolamide; modulation of inflammatory responses through PUFA transport and PPAR activation; regulation of PUFA availability to support neurogenesis; influence on stress-related pathways, including NMDA receptor activation and the hypothalamic-pituitary-adrenal axis; and the facilitation of dopamine receptor trafficking and localization. Next, we discuss preclinical evidence linking FABP function to anxiety- and depression-related behaviours. Finally, we propose that pharmacologically targeting FABP-mediated pathways holds considerable potential as a novel therapeutic strategy for addressing the symptoms associated with mood and anxiety disorders.

Metabolomic Characterization and Bioinformatic Studies of Bioactive Compounds in Two Varieties of Psidium guajava L. Leaf by GC-MS Analysis

The guava tree (Psidium guajava L.) is a tropical plant from the Myrtaceae family. Leaf extracts from this plant have been used in traditional medicine to treat gastrointestinal disorders and exhibit several functional activities that benefit human health. Different varieties of guava trees produce fruits in colors ranging from white to red and present a characteristic metabolic profile in both their leaves and fruits. This study presents a metabolomic characterization of the leaves from two guava varieties: the Caxcana cultivar with yellow fruits and the S-56 accession with pink fruits. Metabolite profiling was conducted using Gas Chromatography-Mass Spectrometry (GC-MS) on methanol extracts, followed by multivariate statistical analysis, including Principal Component Analysis (PCA), and a heat map visualization of compound concentrations in the two varieties. The results identified β-caryophyllene as the major secondary metabolite present in both varieties, with a relative abundance of 16.46% in the Caxcana variety and 23.06% in the S-56 cultivar. Furthermore, in silico analyses, such as network pharmacology and molecular docking, revealed key interactions with proteins such as CB2, PPARα, BAX, BCL2, and AKT1, suggesting potential therapeutic relevance. These findings highlight the pharmacological potential of guava leaf metabolites in natural product chemistry and drug discovery.

Magnolol preserves the integrity of the intestinal epithelial barrier and mitigates intestinal injury through activation of PPAR γ in COPD rat

ETHNOPHARMACOLOGICAL RELEVANCE

Magnolia officinalis Rehder & E.H. Wilson is traditionally used in the treatment of gastrointestinal disorders, diarrhea, and cough. Its main active ingredient, magnolol, exhibits protective effects on the lungs and gastrointestinal tract, including the inhibition of inflammation in these organs.

AIM OF THE STUDY

This work aims to explore the molecular mechanism by which magnolol suppressed Chronic obstructive pulmonary disease (COPD) intestinal damage by improving the intestinal epithelial barrier.

MATERIALS AND METHODS

The study focused on investigating the mitigation effect of magnolol on intestinal injury and epithelial barrier in a COPD rat. Caco-2 cells were induced with TNF-α or IL-1β to establish the barrier injury model in order to explore the direct protective effect of magnolol on the intestinal barrier and elucidate the molecular mechanism by which it activates peroxisome proliferators-activated receptors-γ (PPARγ).

RESULTS

Magnolol significantly improves pulmonary function and tissue damage in COPD rats by inhibiting inflammation, protease imbalance, and oxidative stress. It also suppresses colon tissue damage and inflammation, and protects colon epithelial barrier function by suppressing the decline of tight junction proteins, reducing colon epithelial permeability. In Caco-2 cells, magnolol directly reduces monolayer permeability, increases TEER, and upregulates tight junction protein expression induced by TNF-α or IL-1β. Drug Affinity Responsive Target Stability (DARTS) and thermal shift assays show that magnolol effectively binds to SRC, activating PPARγ signaling in Caco-2 cells and colon tissues of COPD rats. Furthermore, magnolol enhances the binding of PPARγ and RXRα, promoting their activation and entry into the nucleus. The PPARγ inhibitor GW9662 can reverse the effects of magnolol on PPARγ activation and tight junction protein upregulation in IL-1β or TNF-α induced Caco-2 cells.

CONCLUSIONS

This work demonstrates that magnolol enhances lung and intestinal functions in COPD rats, and elucidates its mechanism of action in protecting the intestinal epithelial barrier by activating PPARγ.

Revealing rutaecarpine's promise: A pathway to parkinson's disease relief through PPAR modulation

The pathological mechanisms of Parkinson's disease (PD) is complex, and no definitive cure currently exists. This study identified Rutaecarpine (Rut), an alkaloid extracted from natural plants, as a potential therapeutic agent for PD. To elucidate its mechanisms of action and specific effects in PD, network pharmacology, molecular docking, and experimental validation methods were employed. Our findings demonstrated the efficacy of Rut in ameliorating PD symptoms. Network pharmacology analysis indicated that Rut exerts its therapeutic effects through the PPAR signaling pathway and the lipid pathway. Molecular docking results revealed that Rut forms stable protein-ligand complexes with PPARα and PPARγ. Animal experiments showed that Rut improved motor function in PD mice, protected dopaminergic neurons, ameliorated lipid metabolism disorders, and reduced neuroinflammation. This study identified the critical molecular mechanisms and therapeutic targets of Rut in the treatment of PD, providing a theoretical foundation for future investigations into the pharmacodynamics of Rut as a potential anti-PD agent.

Roles and therapeutic opportunities of ω-3 long-chain polyunsaturated fatty acids in lung cancer

Over the past decades, researchers have continuously investigated the potential functions of long-chain polyunsaturated fatty acids (LCPUFAs) in cancers, including lung cancer. The ω-3 LCPUFAs, primarily consisting of eicosapentaenoic acid and docosahexaenoic acid, were found to modify inflammatory tumor microenvironment, induce cancer cell apoptosis and autophagy, and suppress tumor development when administered alone or with other therapeutical strategies. Although the precise anti-tumor mechanism has not been elucidated yet, ω-3 LCPUFAs are often used in the nutritional treatment of patients with cancer due to their ability to significantly improve patient's nutritional status, increase the sensitivity of tumor cells to treatments, and alleviate cancer-related complications. Here we present the key roles of ω-3 LCPUFAs as dietary supplementations in lung cancer, comprehensively review the recent progress on the underlying mechanisms of cancer cell regulation by ω-3 LCPUFAs, and introduce the application of ω-3 LCPUFAs in the clinical management of lung cancer and its malignant complications.

Interplay of NF-κB and PPAR-γ transcription factors in patients with juvenile systemic lupus erythematosus

OBJECTIVE

Juvenile SLE (jSLE) is an autoimmune disease characterised by the presence of high levels of autoantibodies, predominantly targeting nuclear antigens, resulting in a breakdown of self-tolerance. However, its pathogenesis is multifactorial and poorly understood. The aim of this study was to evaluate the potential of nuclear factor-kappa B (NF-κB) and peroxisome proliferator-activated receptor-gamma (PPAR-γ) as biomarkers for jSLE.

METHODS

In this study, serum NF-κB and PPAR-γ levels were determined by immunoassay in 42 patients with jSLE. In addition, 19 juvenile systemic sclerosis (jSSc) and 25 age-matched healthy children were selected as patient control and healthy control, respectively.

RESULTS

Serum NF-κB levels in patients with jSLE demonstrated a positive trend towards elevation compared with the controls with no significant difference (p=0.030). In addition, serum NF-κB levels in patients with jSSc were significantly higher than that of the healthy controls (p=0.005). Serum PPAR-γ levels were tend to be lower in both patients with jSLE and jSSc compared with the controls, with no significant difference. Specifically, NF-κB levels were significantly higher in patients with jSLE with cumulative damage (PedSDI≥1) compared with those without, at p=0.044. Logistic regression showed that PPAR-γ levels lower than 2.42 ng/mL were associated with the development of jSLE (OR 7.59) and lower than 2.16 ng/mL for jSSc (OR 10.90). The combined high levels of NF-κB with low PPAR-γ increased the risk of developing jSSc by 21.33-fold.

CONCLUSIONS

The observed trend of elevated NF-κB levels and decreased PPAR-γ levels in our study suggests their potential as biomarkers associated with increased proinflammatory signalling in jSLE and jSSc. However, our findings must be regarded as hypothesis-generating and confirmed in larger datasets. Moreover, their roles in monitoring the course of a disease and guiding therapeutic strategies in juvenile systemic autoimmune diseases need to be clearly investigated. Further extension of these findings may lead to better management and improvement in the outcomes of such patients.

Murine skeletal muscle satellite cells isolation and preliminary study on regulation in immune microenvironment during nurse cells formation of Trichinella spiralis infection

As an intracellular parasitic nematode, Trichinella spiralis (T. spiralis) can induce the formation of nurse cells (NC) in host muscles and keep it to survive within the NC for an extended period. The formation of NC is similar to muscle cell injury and repair which lead to the arrest of satellite cells in the G2/M phase and build a suitable parasitic environment for the muscle larvae of T. spiralis. However, the molecular mechanisms involved in skeletal muscle repair through skeletal muscle satellite cells (SMSC) and the host immune response during T. spiralis infection have not been fully elucidated. In this study, histopathological examination revealed that the severity of damage increased as the infection progressed in the soleus muscle. SMSCs were isolated from BALB/c mice infected with T. spiralis at 4, 21 and 35 days post-infection (dpi). The immunological characteristics of these cells were analyzed by real-time PCR and flow cytometry (FCM). FCM analysis revealed a notable increase in the expression of B7 homolog 1 (B7-H1) in SMSCs following T. spiralis infection, while conversely, the expression of inducible costimulatory ligand (ICOSL) significantly decreased. Furthermore, real-time PCR results showed that toll like receptor 3 (TLR3) expression in SMSCs of the infected mice was upregulated at 21 dpi. The expression levels of three subtypes (PPARα, PPARβ and PPARγ) of peroxisome proliferator-activated receptors (PPARs) also increased in the cells. This study highlights the immunological regulation significance of SMSCs host during T. spiralis infection and suggests that SMSCs actively participant in the local immune response to T. spiralis by regulating the interaction between the parasite and the host.

PPAR-γ agonist mitigates intestinal barrier dysfunction and inflammation induced by Clostridioides difficile SlpA in vitro

Clostridioides difficile is the leading cause of healthcare- and antibiotic-associated diarrhea. Surface layer protein A (SlpA), an essential component of the bacterium's outermost layer, contributes to colonization and inflammation. The peroxisome proliferator-activated receptor gamma (PPAR-γ) has been demonstrated to improve intestinal integrity and prevent inflammation in host cells. Here, we investigated the role of PPAR-γ in SlpA-mediated inflammation in Caco-2 cells and THP-1 derived macrophages. The extraction of SlpA was carried out for three toxigenic C. difficile clinical strains (RT126, RT001, RT084) and a non-toxigenic strain (ATCC 700057). The gene expression of tight junction (TJ) proteins and inflammatory markers was determined using RT-qPCR. The production of proinflammatory cytokines and nitric oxide was measured by ELISA and Griss reaction, respectively. Western blotting was performed to detect PPAR-γ level before and after adding its agonist, pioglitazone. SlpA of C. difficile strains enhanced the expression of TLR-4, NF-κB, MyD88, IL-17, MCP-1, IL-8, IL-6, TNF-α, IL-1β, whilst the gene expression level of JAM-A, claudin-1, occludin, PPAR-γ and its receptor (CD36) was decreased in both Caco-2 cells and THP-1 derived macrophages. Moreover, pioglitazone caused a notable elevation in the expression level of PPAR-γ, only following treatment with RT126 SlpA. Besides, pioglitazone pretreatment improved TJ impairment in Caco-2 cells and attenuated proinflammatory cytokine expression in both SlpA-treated cell lines. SlpA can attenuate PPAR-γ expression, trigger TJ disruption, and stimulate inflammatory response in host cells. Notably, these events could be reversed by pretreatment of cells with PPAR-γ agonist. Further experiments are required to corroborate the present findings.

Pharmacological in vitro profiling of Buddleja officinalis flower extracts in the context of dry eye disease

BACKGROUND

Dry eye disease (DED) is caused by inflammation on the ocular surface and insufficient quality or production of the tear film. Due to various harmful environmental conditions, a gradual increase of DED cases has been reported.

HYPOTHESIS/PURPOSE

This study aims for a comprehensive in vitro pharmacological and phytochemical profiling of two different Buddleja officinalis Maxim. extracts to assess their potential for the treatment of DED.

METHODS

A hydroethanolic (BO-HE) and a lead-like enhanced (BO-LLE) B. officinalis extract were phytochemically characterized by UHPLC-UV-MS and UHPLC-ELSD analyses. Afterwards, the effects of either BO-HE or BO-LLE on in vitro dry eye models, including human corneal epithelial cell-transformed (HCE-T) cells, immortalized human meibomian gland epithelial cells (IHMGECs) and human leukemia monocytic (THP-1) cells, and Jurkat cells, were investigated.

RESULTS

Both extracts exhibited strong anti-inflammatory properties with free radical scavenging activities and reduction of intracellular reactive oxygen species (ROS) in UVB-exposed HCE-T cells. Treatment with BO-HE or BO-LLE showed wound healing capacities. Moreover, both extracts differentially modulate mediator secretion in UVB-exposed HCE-T cells. In IHMGECs, the size of secreted lipid droplets was larger in BO-LLE treated cells. As for immune cells, a significant reduction in levels of TNF-α and IL-6 secretion by lipopolysaccharide (LPS)-exposed THP-1 cells was observed. Additionally, BO-LLE effectively inhibited intracellular calcium influx in Jurkat cells even at low concentrations.

CONCLUSION

The results of this study demonstrate pharmacological potential of B. officinalis flowers for the treatment of DED pathology with BO-LLE exerting a slightly more beneficial profile than BO-HE.

Obesity and hormonal influences on asthma: Mechanisms, management challenges, and emerging therapeutic strategies

Obesity and hormone dysregulation, common comorbidities of asthma, not only influence asthma risk and onset but can also complicate its management. The pathobiologic characteristics of obesity, such as insulin resistance and metabolism alterations, can impact lung function and airway inflammation while highlighting potential opportunities for therapeutic intervention. Likewise, obesity alters immune cell phenotypes and corticosteroid pharmacokinetics. Hormones such as sex hormones, incretins, and thyroid hormones can also affect asthma. This review highlights the mechanisms underlying obesity-related asthma and hormonal pathologies while exploring potential therapeutic strategies and the need for more research and innovative approaches in managing these comorbid conditions.

Selective PPARδ Agonist GW501516 Protects Against LPS-Induced Macrophage Inflammation and Acute Liver Failure in Mice via Suppressing Inflammatory Mediators

Inflammation is critical in the development of acute liver failure (ALF). Peroxisome proliferator-activated receptor delta (PPARδ) regulates anti-inflammatory responses and is protective in several diseases such as obesity and cancer. However, the beneficial effects and underlying mechanisms of PPARδ agonist GW501516 in ALF remain unclear. This study investigated the molecular mechanisms underlying the anti-inflammatory effects of GW501516 in macrophages and assessed its protective potential against lipopolysaccharide (LPS)/galactosamine (GalN)-induced ALF. In vivo administration of GW501516 significantly reduced LPS/GalN-induced hepatotoxicity, as evidenced by lower mortality, decreased liver damage, and attenuated secretion of IL-1β, IL-6, and TNF-α. GW501516 treatment also decreased LPS-induced nitric oxide synthase 2 (NOS2) expression and nitric oxide (NO) production in RAW264.7 cells, an effect reversed by PPARδ siRNA. Additionally, GW501516 inhibited LPS-induced phosphorylation of p38 and c-Jun N-terminal kinase (JNK), suggesting that inactivation of these MAPKs contributes to its effects. The secretion of IL-6, TNF-α, and NF-κB DNA-binding activity were also suppressed by GW501516, while the nuclear translocation of the NF-κB p65 subunit was unaffected. In conclusion, our findings suggest that GW501516 exerts protective effects in ALF by inhibiting the production of inflammatory mediators. Therefore, GW501516 may act as a potential agent for developing anti-inflammatory therapies for ALF.

Investigation in the cannabigerol derivative VCE-003.2 as a disease-modifying agent in a mouse model of experimental synucleinopathy

BACKGROUND

The cannabigerol derivative VCE-003.2, which has activity at the peroxisome proliferator-activated receptor-γ has afforded neuroprotection in experimental models of Parkinson's disease (PD) based on mitochondrial dysfunction (6-hydroxydopamine-lesioned mice) and neuroinflammation (LPS-lesioned mice). Now, we aim to explore VCE-003.2 neuroprotective properties in a PD model that also involves protein dysregulation, other key event in PD pathogenesis.

METHODS

To this end, an adeno-associated viral vector serotype 9 coding for a mutated form of the α-synuclein gene (AAV9-SynA53T) was unilaterally delivered in the substantia nigra pars compacta (SNpc) of mice. This model leads to motor impairment and progressive loss of tyrosine hydroxylase-labelled neurons in the SNpc.

RESULTS

Oral administration of VCE-003.2 at 20 mg/kg for 14 days improved the performance of mice injected with AAV9-SynA53T in various motor tests, correlating with the preservation of tyrosine hydroxylase-labelled neurons in the SNpc. VCE-003.2 also reduced reactive microgliosis and astrogliosis in the SNpc. Furthermore, we conducted a transcriptomic analysis in the striatum of mice injected with AAV9-SynA53T and treated with either VCE-003.2 or vehicle, as well as control animals. This analysis aimed to identify gene families specifically altered by the pathology and/or VCE-003.2 treatment. Our data revealed pathology-induced changes in genes related to mitochondrial function, lysosomal cell pathways, immune responses, and lipid metabolism. In contrast, VCE-003.2 treatment predominantly affected the immune response through interferon signaling.

CONCLUSION

Our study broadens the neuroprotective potential of VCE-003.2, previously described against mitochondrial dysfunction, oxidative stress, glial reactivity and neuroinflammation in PD. We now demonstrate its efficacy against another key pathogenic event in PD as α-synuclein dysregulation. Furthermore, our investigation sheds light on the molecular mechanisms underlying VCE-003.2 revealing its role in regulating interferon signaling. These findings, together with a favorable ADMET profile, enhance the preclinical interest of VCE-003.2 towards its future clinical development in PD.

Roles of lipid droplets and related proteins in metabolic diseases

Lipid droplets (LDs), which are active organelles, derive from the monolayer membrane of the endoplasmic reticulum and encapsulate neutral lipids internally. LD-associated proteins like RAB, those in the PLIN family, and those in the CIDE family participate in LD formation and development, and they are active players in various diseases, organelles, and metabolic processes (i.e., obesity, non-alcoholic fatty liver disease, and autophagy). Our synthesis on existing research includes insights from the formation of LDs to their mechanisms of action, to provide an overview needed for advancing research into metabolic diseases and lipid metabolism.

Early biomarkers in the presymptomatic phase of cognitive impairment: changes in the endocannabinoidome and serotonergic pathways in Alzheimer's-prone mice after mTBI

BACKGROUND

Despite extensive studies on the neurobiological correlates of traumatic brain injury (TBI), little is known about its molecular determinants on long-term consequences, such as dementia and Alzheimer's disease (AD).

METHODS

Here, we carried out behavioural studies and an extensive biomolecular analysis, including inflammatory cytokines, gene expression and the combination of LC-HRMS and MALDI-MS Imaging to elucidate the targeted metabolomics and lipidomics spatiotemporal alterations of brains from wild-type and APP-SWE mice, a genetic model of AD, at the presymptomatic stage, subjected to mild TBI.

RESULTS

We found that brain injury does not affect cognitive performance in APP-SWE mice. However, we detected an increase of key hallmarks of AD, including Aβ1-42 levels and BACE1 expression, in the cortices of traumatized transgenic mice. Moreover, significant changes in the expanded endocannabinoid (eCB) system, or endocannabinoidome (eCBome), occurred, including increased levels of the endocannabinoid 2-AG in APP-SWE mice in both the cortex and hippocampus, and N-acylserotonins, detected for the first time in the brain. The gene expression of enzymes for the biosynthesis and inactivation of eCBs and eCB-like mediators, and some of their main molecular targets, also underwent significant changes. We also identified the formation of heteromers between cannabinoid 1 (CB1) and serotonergic 2A (5HT2A) receptors, whose levels increased in the cortex of APP-SWE mTBI mice, possibly contributing to the exacerbated pathophysiology of AD induced by the trauma.

CONCLUSIONS

Mild TBI induces biochemical changes in AD genetically predisposed mice and the eCBome may play a role in the pathogenetic link between brain injury and neurodegenerative disorders also by interacting with the serotonergic system.

Cellular metabolism regulates the differentiation and function of T-cell subsets

T cells are an important component of adaptive immunity and protect the host from infectious diseases and cancers. However, uncontrolled T cell immunity may cause autoimmune disorders. In both situations, antigen-specific T cells undergo clonal expansion upon the engagement and activation of antigens. Cellular metabolism is reprogrammed to meet the increase in bioenergetic and biosynthetic demands associated with effector T cell expansion. Metabolites not only serve as building blocks or energy sources to fuel cell growth and expansion but also regulate a broad spectrum of cellular signals that instruct the differentiation of multiple T cell subsets. The realm of immunometabolism research is undergoing swift advancements. Encapsulating all the recent progress within this concise review in not possible. Instead, our objective is to provide a succinct introduction to this swiftly progressing research, concentrating on the metabolic intricacies of three pivotal nutrient classes-lipids, glucose, and amino acids-in T cells. We shed light on recent investigations elucidating the roles of these three groups of metabolites in mediating the metabolic and immune functions of T cells. Moreover, we delve into the prospect of "editing" metabolic pathways within T cells using pharmacological or genetic approaches, with the aim of synergizing this approach with existing immunotherapies and enhancing the efficacy of antitumor and antiinfection immune responses.

Advances in polysaccharides of natural source of anti-diabetes effect and mechanism

PURPOSE

Diabetes is a chronic disease in metabolic disorder, and the pathology is characterized by insulin resistance and insulin secretion disorder in blood. In current, many studies have revealed that polysaccharides extracted from natural sources with significant anti-diabetic effects. Natural polysaccharides can ameliorate diabetes through different action mechanisms. All these polysaccharides are expected to have an important role in the clinic.

METHODS

Existing polysaccharides for the treatment of diabetes are reviewed, and the mechanism of polysaccharides in the treatment of diabetes and its structural characteristics are described in detail.

RESULTS

This article introduced the natural polysaccharide through different mechanisms of action in the treatment of diabetes, including oxidative stress, apoptosis, inflammatory response and regulation of intestinal bacteria. Natural polysaccharides can treat of diabetes by regulating signaling pathways is also a research hotspot. In addition, the structural characteristics of polysaccharides were explored. There are some structure-activity relationships between natural polysaccharides and the treatment of diabetes.

Role of Brain Liver X Receptor in Parkinson's Disease: Hidden Treasure and Emerging Opportunities

Parkinson's disease (PD) is a neurodegenerative disease due to the degeneration of dopaminergic neurons (DNs) in the substantia nigra (SN). The liver X receptor (LXR) is involved in different neurodegenerative diseases. Therefore, the objective of the present review was to clarify the possible role of LXR in PD neuropathology. LXRs are the most common nuclear receptors of transcription factors that regulate cholesterol metabolism and have pleiotropic effects, including anti-inflammatory effects and reducing intracellular cholesterol accumulation. LXRs are highly expressed in the adult brain and act as endogenous sensors for intracellular cholesterol. LXRs have neuroprotective effects against the development of neuroinflammation in different neurodegenerative diseases by inhibiting the expression of pro-inflammatory cytokines. LXRs play an essential role in mitigating PD neuropathology by reducing the expression of inflammatory signaling pathways, neuroinflammation, oxidative stress, mitochondrial dysfunction, and enhancement of BDNF signaling.In conclusion, LXRs, through regulating brain cholesterol homeostasis, may be effectual in PD. Also, inhibition of node-like receptor pyrin 3 (NLRP3) inflammasome and nuclear factor kappa B (NF-κB) by LXRs could effectively prevent neuroinflammation in PD. Taken together, LXRs play a crucial role in PD neuropathology by inhibiting neuroinflammation and associated degeneration of DNs.

ABHD6 suppression promotes anti-inflammatory polarization of adipose tissue macrophages via 2-monoacylglycerol/PPAR signaling in obese mice

OBJECTIVE

Pro-inflammatory polarization of adipose tissue macrophages (ATMs) plays a critical role in the pathogenesis of obesity-associated chronic inflammation. However, little is known about the role of lipids in the regulation of ATMs polarity and inflammation in response to metabolic stress. Deletion of α/β-hydrolase domain-containing 6 (ABHD6), a monoacylglycerol (MAG) hydrolase, has been shown to protect against diet-induced obesity and insulin resistance.

METHODS

Here we investigated the immunometabolic role of macrophage ABHD6 in response to nutrient excess using whole-body ABHD6-KO mice and human and murine macrophage cell-lines treated with KT203, a selective and potent pharmacological ABHD6 inhibitor.

RESULTS

KO mice on high-fat diet showed lower susceptibility to systemic diet-induced inflammation. Moreover, in the setting of overnutrition, stromal vascular cells from gonadal fat of KO vs. control mice contained lower number of M1 macrophages and exhibited enhanced levels of metabolically activated macrophages (MMe) and M2 markers, oxygen consumption, and interleukin-6 (IL-6) release. Likewise, under in vitro nutri-stress condition, inhibition of ABHD6 in MMe-polarized macrophages attenuated the expression and release of pro-inflammatory cytokines and M1 markers and induced the upregulation of lipid metabolism genes. ABHD6-inhibited MMe macrophages showed elevated levels of peroxisome proliferator-activated receptors (PPARs) and 2-MAG species. Notably, among different MAG species, only 2-MAG treatment led to increased levels of PPAR target genes in MMe macrophages.

CONCLUSIONS

Collectively, our findings identify ABHD6 as a key component of pro-inflammatory macrophage activation in response to excess nutrition and implicate an endogenous macrophage lipolysis/ABHD6/2-MAG/PPARs cascade, as a lipid signaling and immunometabolic pathway, which favors the anti-inflammatory polarization of ATMs in obesity.

Synthesis, kinetic studies and in-silico investigations of novel quinolinyl-iminothiazolines as alkaline phosphatase inhibitors

Deposition of hydroxyapatite (HA) or alkaline phosphate crystals on soft tissues causes the pathological calcification diseases comprising of end-stage osteoarthritis (OA), ankylosing spondylitis (AS), medial artery calcification and tumour calcification. The pathological calcification is symbolised by increased concentration of tissue non-specific alkaline phosphatase (TNAP). An efficient therapeutic strategy to eradicate these diseases is required, and for this the alkaline phosphatase inhibitors can play a potential role. In this context a series of novel quinolinyl iminothiazolines was synthesised and evaluated for alkaline phosphatase inhibition potential. All the compounds were subjected to DFT studies where N-benzamide quinolinyl iminothiazoline (6g), N-dichlorobenzamide quinolinyl iminothiazoline (6i) and N-nitrobenzamide quinolinyl iminothiazoline (6j) were found as the most reactive compounds. Then during the in-vitro testing, the compound N-benzamide quinolinyl iminothiazoline (6g) exhibited the maximum alkaline phosphatase inhibitory effect (IC₅₀ = 0.337 ± 0.015 µM) as compared to other analogues and standard KH₂PO₄ (IC₅₀ = 5.245 ± 0.477 µM). The results were supported by the molecular docking studies, molecular dynamics simulations and kinetic analysis which also revealed the inhibitory potential of compound N-benzamide quinolinyl iminothiazoline (6g) against alkaline phosphatase. This compound can be act as lead molecule for the synthesis of more effective inhibitors and can be suggested to test at the molecular level.

[Beneficial effects of ketogenic diet for Alzheimer's disease management]

Alzheimer's disease (AD) is a neurodegenerative disease that affects almost 1 million people in France and 55 million in the world. This pathology is a global health preoccupation because of the lack of efficient curative treatment and the increase of its prevalence. During the last decade, the comprehension of pathophysiological mechanisms involved in AD have been improved. Amyloid plaques and neurofibrillary tangles accumulation are characteristic of Alzheimer's brain patients, accompanied by increased brain inflammation and oxidative stress, impaired cerebral metabolism of glucose and mitochondrial function. Treatment of AD includes different approaches, as pharmacology, psychology support, physiotherapy, and speech therapy. However, these interventions do not have a curative effect, but only compensatory on the disease. Ketogenic diet (KD), a low-carbohydrates and high-fat diet, associated with a medium-chain triglycerides intake (MCTs) might induce benefices for Alzheimer disease patients. Carbohydrate restriction and MCTs promotes the production of ketone bodies from fatty acid degradation. These metabolites replacing glucose, serve the brain as energetic substrates, and induce neuroprotective effects. Such a nutritional support might slow down the disease progression and improve cognitive abilities of patients. This review aims to examine the neuroprotective mechanisms of KD in AD progression and describes the advantages and limitations of KD as a therapeutic strategy.

24-Norursodeoxycholic acid ameliorates experimental alcohol-related liver disease and activates hepatic PPARγ

Background & Aims

Alcohol-related liver disease (ALD) is a global healthcare challenge with limited treatment options. 24-Norursodeoxycholic acid (NorUDCA) is a synthetic bile acid with anti-inflammatory properties in experimental and human cholestatic liver diseases. In the present study, we explored the efficacy of norUDCA in experimental ALD.

Methods

NorUDCA was tested in a preventive and therapeutic setting in an experimental ALD model (Lieber-DeCarli diet enriched with ethanol). Liver disease was phenotypically evaluated using histology and biochemical methods, and anti-inflammatory properties and peroxisome proliferator-activated receptor gamma activation by norUDCA were evaluated in cellular model systems.

Results

NorUDCA administration ameliorated ethanol-induced liver injury, reduced hepatocyte death, and reduced the expression of hepatic pro-inflammatory cytokines including tumour necrosis factor (Tnf), Il-1β, Il-6, and Il-10. NorUDCA shifted hepatic macrophages towards an anti-inflammatory M2 phenotype. Further, norUDCA administration altered the composition of the intestinal microbiota, specifically increasing the abundance of Roseburia, Enterobacteriaceae, and Clostridum spp. In a therapeutic model, norUDCA also ameliorated ethanol-induced liver injury. Moreover, norUDCA suppressed lipopolysaccharide-induced IL-6 expression in human peripheral blood mononuclear cells and evoked peroxisome proliferator-activated receptor gamma activation.

Conclusions

NorUDCA ameliorated experimental ALD, protected against hepatic inflammation, and affected gut microbial commensalism. NorUDCA could serve as a novel therapeutic agent in the future management of patients with ALD.

Impact and implications

Alcohol-related liver disease is a global healthcare concern with limited treatment options. 24-Norursodeoxycholic acid (NorUDCA) is a modified bile acid, which was proven to be effective in human cholestatic liver diseases. In the present study, we found a protective effect of norUDCA in experimental alcoholic liver disease. For patients with ALD, norUDCA could be a potential new treatment option.

Drug Repositioning of Pioglitazone in Management and Improving the Cognitive Function among the Patients With Mild to Moderate Alzheimer's Disease: A Systematic Review and Meta-Analysis

Background

Disease-modifying agents like Pioglitazone have shown promising effects on neuroinflammation and homeostasis of amyloid plaques, but there is a lack of research papers providing conclusive evidence.

Objectives

This study is aimed to determine the safety and efficacy of Pioglitazone in improving cognitive function in patients with mild-moderate Alzheimer's disease (AD).

Materials and Methods

Trials published in the last 12 years were identified from PubMed, Scopus, Cochrane Central, and other trial registries. Five hundred twenty-five records were obtained, from which five studies were included for quantitative analysis. Studies comparing Pioglitazone with a suitable placebo or other oral hypoglycemic agent were considered for review. Data was extracted using a pretested form, which was followed by a risk of bias assessment (ROB) with Cochrane's ROB assessment tool.

Results

This meta-analysis included studies where Pioglitazone (15-30 mg) was compared to other oral hypoglycemic agents, placebo, or diabetic diet for a minimum duration of 6 months. Pioglitazone did not show a statistically significant improvement in Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) scores [mean difference (MD): -1.16; 95% confidence interval (CI): -4.14-1.81]. By conducting sensitivity analysis with the removal of one study, significant efficacy was obtained [MD: -2.75; 95% CI: -4.84--0.66]. The Wechsler Memory Scale-Revised logical memory I (WMS-R) scores had a significant improvement in the Pioglitazone group [MD: 2.02; 95% CI: 0.09-3.95].

Conclusion

Pioglitazone is a safe medication that has a promising effect in slowing the advancement of AD.

PPARs/macrophages: A bridge between the inflammatory response and lipid metabolism in autoimmune diseases

Autoimmune diseases (AIDs) are a collection of pathologies that arise from autoimmune reactions and lead to the destruction and damage of the body's tissues and cellular components, ultimately resulting in tissue damage and organ dysfunction. The anti-inflammatory effects of the peroxisome proliferator-activated receptor (PPAR), a pivotal regulator of lipid metabolism, are crucial in the context of AIDs. PPAR mitigates AIDs by modulating macrophage polarization and suppressing the inflammatory response. Numerous studies have demonstrated the crucial involvement of lipid metabolism and phenotypic switching in classically activated (M1)/alternatively activated (M2)-like macrophages in the inflammatory pathway of AIDs. However, the precise mechanism by which PPAR, a critical mediator between of lipid metabolism and macrophage polarization, regulates macrophage polarization remains unclear. This review aimed to clarify the role of PPAR and macrophages in the triangular relationship among AIDs, lipid metabolism, and inflammatory response, and aims to summarize the mechanism of the PPAR-mediated macrophage activation and polarization, which impacts the progression and development of AIDs.

Altered expression, but small contribution, of the histone demethylase KDM6A in obstructive uropathy in mice

Epigenetic processes have emerged as important modulators of kidney health and disease. Here, we studied the role of KDM6A (a histone demethylase that escapes X-chromosome inactivation) in kidney tubule epithelial cells. We initially observed an increase in tubule cell Kdm6a mRNA in male mice with unilateral ureteral obstruction (UUO). However, tubule cell knockout of KDM6A had relatively minor consequences, characterized by a small reduction in apoptosis, increase in inflammation and downregulation of the peroxisome proliferator-activated receptor (PPAR) signaling pathway. In proximal tubule lineage HK-2 cells, KDM6A knockdown decreased PPARγ coactivator-1α (PGC-1α) protein levels and mRNA levels of the encoding gene, PPARGC1A. Tubule cell Kdm6a mRNA levels were approximately 2-fold higher in female mice than in male mice, both under sham and UUO conditions. However, kidney fibrosis after UUO was similar in both sexes. The findings demonstrate Kdm6a to be a dynamically regulated gene in the kidney tubule, varying in expression levels by sex and in response to injury. Despite the context-dependent variation in Kdm6a expression, knockout of tubule cell KDM6A has subtle (albeit non-negligible) effects in the adult kidney, at least in males.

Gene network based analysis identifies a coexpression module involved in regulating plasma lipids with high-fat diet response

Plasma lipids are modulated by gene variants and many environmental factors, including diet-associated weight gain. However, understanding how these factors jointly interact to influence molecular networks that regulate plasma lipid levels is limited. Here, we took advantage of the BXD recombinant inbred family of mice to query weight gain as an environmental stressor on plasma lipids. Coexpression networks were examined in both nonobese and obese livers, and a network was identified that specifically responded to the obesogenic diet. This obesity-associated module was significantly associated with plasma lipid levels and enriched with genes known to have functions related to inflammation and lipid homeostasis. We identified key drivers of the module, including Cidec, Cidea, Pparg, Cd36, and Apoa4. The Pparg emerged as a potential master regulator of the module as it can directly target 19 of the top 30 hub genes. Importantly, activation of this module is causally linked to lipid metabolism in humans, as illustrated by correlation analysis and inverse-variance weighed Mendelian randomization. Our findings provide novel insights into gene-by-environment interactions for plasma lipid metabolism that may ultimately contribute to new biomarkers, better diagnostics, and improved approaches to prevent or treat dyslipidemia in patients.

Peroxisome proliferator-activated receptors, farnesoid X receptor, and dual modulating drugs in hypertension

Hypertension characterized by an elevated blood pressure is a cardiovascular disease that afflicts greater than one in every three adults worldwide. Nuclear receptors are large superfamily of DNA-binding transcription factors that target genes to regulate metabolic and cardiovascular function. Drugs have been developed for nuclear receptors such as peroxisome proliferator-activated receptors (PPARα and PPARγ) and farnesoid X receptor (FXR). PPARα, PPARγ, and FXR agonists are used clinically to treat lipid disorders and metabolic diseases. Evidence from clinical studies and animal hypertension models have demonstrated that PPARα, PPARγ, and FXR agonism can lower blood pressure and decrease end organ damage which could be useful for the treatment of hypertension in patients with metabolic diseases. Unfortunately, PPAR and FXR agonists have unwanted clinical side effects. There have been recent developments to limit side effects for PPAR and FXR agonists. Combining PPAR and FXR agonism with soluble epoxide hydrolase (sEH) inhibition or Takeda G protein receptor 5 (TGR5) agonism has been demonstrated in preclinical studies to have actions that would decrease clinical side effects. In addition, these dual modulating drugs have been demonstrated in preclinical studies to have blood pressure lowering, anti-fibrotic, and anti-inflammatory actions. There is now an opportunity to thoroughly test these novel dual modulators in animal models of hypertension associated with metabolic diseases. In particular, these newly developed dual modulating PPAR and FXR drugs could be beneficial for the treatment of metabolic diseases, organ fibrosis, and hypertension.

Non-Alcoholic Fatty Liver Disease: Translating Disease Mechanisms into Therapeutics Using Animal Models

Nonalcoholic fatty liver disease (NAFLD) is a range of pathologies arising from fat accumulation in the liver in the absence of excess alcohol use or other causes of liver disease. Its complications include cirrhosis and liver failure, hepatocellular carcinoma, and eventual death. NAFLD is the most common cause of liver disease globally and is estimated to affect nearly one-third of individuals in the United States. Despite knowledge that the incidence and prevalence of NAFLD are increasing, the pathophysiology of the disease and its progression to cirrhosis remain insufficiently understood. The molecular pathogenesis of NAFLD involves insulin resistance, inflammation, oxidative stress, and endoplasmic reticulum stress. Better insight into these molecular pathways would allow for therapies that target specific stages of NAFLD. Preclinical animal models have aided in defining these mechanisms and have served as platforms for screening and testing of potential therapeutic approaches. In this review, we will discuss the cellular and molecular mechanisms thought to contribute to NAFLD, with a focus on the role of animal models in elucidating these mechanisms and in developing therapies.

Roles and regulation of microglia activity in multiple sclerosis: insights from animal models

As resident macrophages of the CNS, microglia are critical immune effectors of inflammatory lesions and associated neural dysfunctions. In multiple sclerosis (MS) and its animal models, chronic microglial inflammatory activity damages myelin and disrupts axonal and synaptic activity. In contrast to these detrimental effects, the potent phagocytic and tissue-remodelling capabilities of microglia support critical endogenous repair mechanisms. Although these opposing capabilities have long been appreciated, a precise understanding of their underlying molecular effectors is only beginning to emerge. Here, we review recent advances in our understanding of the roles of microglia in animal models of MS and demyelinating lesions and the mechanisms that underlie their damaging and repairing activities. We also discuss how the structured organization and regulation of the genome enables complex transcriptional heterogeneity within the microglial cell population at demyelinating lesions.

Novel Derivatives of Eugenol as a New Class of PPARγ Agonists in Treating Inflammation: Design, Synthesis, SAR Analysis and In Vitro Anti-Inflammatory Activity

The main objective of this research was to develop novel compounds from readily accessed natural products especially eugenol with potential biological activity. Eugenol, the principal chemical constituent of clove (Eugenia caryophyllata) from the family Myrtaceae is renowned for its pharmacological properties, which include analgesic, antidiabetic, antioxidant, anticancer, and anti-inflammatory effects. According to reports, PPARγ regulates inflammatory reactions. The synthesized compounds were structurally analyzed using FT-IR, ¹HNMR, ¹³CNMR, and mass spectroscopy techniques. Molecular docking was performed to analyze binding free energy and important amino acids involved in the interaction between synthesized derivatives and the target protein. The development of the structure-activity relationship is based on computational studies. Additionally, the stability of the best-docked protein-ligand complexes was assessed using molecular dynamic modeling. The in-vitro PPARγ competitive binding Lanthascreen TR-FRET assay was used to confirm the affinity of compounds to the target protein. All the synthesized derivatives were evaluated for an in vitro anti-inflammatory activity using an albumin denaturation assay and HRBC membrane stabilization at varying concentrations from 6.25 to 400 µM. In this background, with the aid of computational research, we were able to design six novel derivatives of eugenol synthesized, analyzed, and utilized TR-FRET competitive binding assay to screen them for their ability to bind PPARγ. Anti-inflammatory activity evaluation through in vitro albumin denaturation and HRBC method revealed that 1f exhibits maximum inhibition of heat-induced albumin denaturation at 50% and 85% protection against HRBC lysis at 200 and 400 µM, respectively. Overall, we found novel derivatives of eugenol that could potentially reduce inflammation by PPARγ agonism.

Molecular Docking Identifies 1,8-Cineole (Eucalyptol) as A Novel PPARγ Agonist That Alleviates Colon Inflammation

Inflammatory bowel disease, comprising Crohn's disease (CD) and ulcerative colitis (UC), is often debilitating. The disease etiology is multifactorial, involving genetic susceptibility, microbial dysregulation, abnormal immune activation, and environmental factors. Currently, available drug therapies are associated with adverse effects when used long-term. Therefore, the search for new drug candidates to treat IBD is imperative. The peroxisome proliferator-activated receptor-γ (PPARγ) is highly expressed in the colon. PPARγ plays a vital role in regulating colonic inflammation. 1,8-cineole, also known as eucalyptol, is a monoterpene oxide present in various aromatic plants which possess potent anti-inflammatory activity. Molecular docking and dynamics studies revealed that 1,8-cineole binds to PPARγ and if it were an agonist, that would explain the anti-inflammatory effects of 1,8-cineole. Therefore, we investigated the role of 1,8-cineole in colonic inflammation, using both in vivo and in vitro experimental approaches. Dextran sodium sulfate (DSS)-induced colitis was used as the in vivo model, and tumor necrosis factor-α (TNFα)-stimulated HT-29 cells as the in vitro model. 1,8-cineole treatment significantly decreased the inflammatory response in DSS-induced colitis mice. 1,8-cineole treatment also increased nuclear factor erythroid 2-related factor 2 (Nrf2) translocation into the nucleus to induce potent antioxidant effects. 1,8-cineole also increased colonic PPARγ protein expression. Similarly, 1,8-cineole decreased proinflammatory chemokine production and increased PPARγ protein expression in TNFα-stimulated HT-29 cells. 1,8-cineole also increased PPARγ promoter activity time-dependently. Because of its potent anti-inflammatory effects, 1,8-cineole may be valuable in treating IBD.

Multi-organ single-cell analysis reveals an on/off switch system with potential for personalized treatment of immunological diseases

Prioritization of disease mechanisms, biomarkers, and drug targets in immune-mediated inflammatory diseases (IMIDs) is complicated by altered interactions between thousands of genes. Our multi-organ single-cell RNA sequencing of a mouse IMID model, namely collagen-induced arthritis, shows highly complex and heterogeneous expression changes in all analyzed organs, even though only joints showed signs of inflammation. We organized those into a multi-organ multicellular disease model, which shows predicted molecular interactions within and between organs. That model supports that inflammation is switched on or off by altered balance between pro- and anti-inflammatory upstream regulators (URs) and downstream pathways. Meta-analyses of human IMIDs show a similar, but graded, on/off switch system. This system has the potential to prioritize, diagnose, and treat optimal combinations of URs on the levels of IMIDs, subgroups, and individual patients. That potential is supported by UR analyses in more than 600 sera from patients with systemic lupus erythematosus.

Irisin drives macrophage anti-inflammatory differentiation via JAK2-STAT6-dependent activation of PPARγ and Nrf2 signaling

Irisin is an exercise-induced myokine that alleviates inflammation and obesity. The induction of anti-inflammatory (M2) macrophage is facilitated for treatment of sepsis and associated lung damage. However, whether irisin drives macrophage M2 polarization remains unclear. Here, we found that irisin induced-macrophage anti-inflammatory differentiation in vivo using an LPS-induced septic mice model and in vitro using RAW64.7 cells and bone marrow-derived macrophages (BMDMs). Irisin also promoted the expression, phosphorylation, and nuclear translocation of peroxisome proliferator-activated receptor gamma (PPAR-γ) and nuclear factor-erythroid 2-related factor 2 (Nrf2). Inhibition or knockdown of PPAR-γ and Nrf2 abolished irisin-induced accumulation of M2 macrophage markers, such as interleukin (IL)-10 and Arginase 1. Furthermore, dual-luciferase reporter and chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) assays confirmed that STAT6 boosts PPAR-γ and Nrf2 transcription by binding to their DNA promoters in irisin-stimulated macrophages. In contrast, STAT6 shRNA blocked the irisin-induced activation of Pparγ, Nrf2, and related downstream genes. Moreover, the interaction of irisin with its ligand integrin αVβ5 remarkably promoted Janus kinase 2 (JAK2) phosphorylation, while inhibition or knockdown of integrin αVβ5 and JAK2 attenuated the activation of STAT6, PPAR-γ, and Nrf2 signaling. Interestingly, co-immunoprecipitation (Co-IP) assay also revealed that the binding between JAK2 and integrin αVβ5 is critical for irisin-induced macrophage anti-inflammatory differentiation by enhancing the activation of the JAK2-STAT6 pathway. In conclusion, irisin boosted M2 macrophage differentiation by inducing JAK2-STAT6-dependent transcriptional activation of the PPAR-γ-related anti-inflammatory system and Nrf2-related antioxidant genes. The findings of this study suggest that the administration of irisin is a novel and promising therapeutic strategy for infectious and inflammatory diseases.

Quinolinate promotes macrophage-induced immune tolerance in glioblastoma through the NMDAR/PPARγ signaling axis

There has been considerable scientific effort dedicated to understanding the biologic consequence and therapeutic implications of aberrant tryptophan metabolism in brain tumors and neurodegenerative diseases. A majority of this work has focused on the upstream metabolism of tryptophan; however, this has resulted in limited clinical application. Using global metabolomic profiling of patient-derived brain tumors, we identify the downstream metabolism of tryptophan and accumulation of quinolinate (QA) as a metabolic node in glioblastoma and demonstrate its critical role in promoting immune tolerance. QA acts as a metabolic checkpoint in glioblastoma by inducing NMDA receptor activation and Foxo1/PPARγ signaling in macrophages, resulting in a tumor supportive phenotype. Using a genetically-engineered mouse model designed to inhibit production of QA, we identify kynureninase as a promising therapeutic target to revert the potent immune suppressive microenvironment in glioblastoma. These findings offer an opportunity to revisit the biologic consequence of this pathway as it relates to oncogenesis and neurodegenerative disease and a framework for developing immune modulatory agents to further clinical gains in these otherwise incurable diseases.

Peroxisome proliferator-activated receptor (PPAR) agonists as a potential therapy for inherited metabolic disorders

Inherited metabolic disorders (IMDs) are genetic disorders that cause a disruption of a specific metabolic pathway leading to biochemical, clinical and pathophysiological sequelae. While the metabolite abnormalities in body fluids and tissues can usually be defined by directed or broad-spectrum metabolomic analysis, the pathophysiology of these changes is often not obvious. Mounting evidence has revealed that secondary mitochondrial dysfunction, mainly oxidative phosphorylation impairment and elevated reactive oxygen species, plays a pivotal role in many disorders. Peroxisomal proliferator-activated receptors (PPARs) consist of a group of nuclear hormone receptors (PPARα, PPARβ/δ, and PPARγ) that regulate multiple cellular functions and processes, including response to oxidative stress, inflammation, lipid metabolism, and mitochondrial bioenergetics and biogenesis. In this context, the activation of PPARs has been shown to stimulate oxidative phosphorylation and reduce reactive species levels. Thus, pharmacological treatment with PPAR activators, such as fibrates, has gained much attention in the last 15 years. This review summarizes preclinical (animal models and patient-derived cells) and clinical data on the effect of PPARs in IMDs.

Immunometabolic Signature during Respiratory Viral Infection: A Potential Target for Host-Directed Therapies

RNA viruses are known to induce a wide variety of respiratory tract illnesses, from simple colds to the latest coronavirus pandemic, causing effects on public health and the economy worldwide. Influenza virus (IV), parainfluenza virus (PIV), metapneumovirus (MPV), respiratory syncytial virus (RSV), rhinovirus (RhV), and coronavirus (CoV) are some of the most notable RNA viruses. Despite efforts, due to the high mutation rate, there are still no effective and scalable treatments that accompany the rapid emergence of new diseases associated with respiratory RNA viruses. Host-directed therapies have been applied to combat RNA virus infections by interfering with host cell factors that enhance the ability of immune cells to respond against those pathogens. The reprogramming of immune cell metabolism has recently emerged as a central mechanism in orchestrated immunity against respiratory viruses. Therefore, understanding the metabolic signature of immune cells during virus infection may be a promising tool for developing host-directed therapies. In this review, we revisit recent findings on the immunometabolic modulation in response to infection and discuss how these metabolic pathways may be used as targets for new therapies to combat illnesses caused by respiratory RNA viruses.

WY14643 Increases Herpesvirus Replication and Inhibits IFNβ Production Independently of PPARα Expression

Peroxisome proliferator activated receptor (PPAR) agonists are commonly used to treat metabolic disorders in humans because they regulate fatty acid oxidation and cholesterol metabolism. In addition to their roles in controlling metabolism, PPAR agonists also regulate inflammation and are immunosuppressive in models of autoimmunity. We aimed to test whether activation of PPARα with clinically relevant ligands could impact gammaherpesvirus infection using murine gammaherpesvirus-68 (MHV68, MuHV-4). We found that PPAR agonists WY14643 and fenofibrate increased herpesvirus replication in vitro. In vivo, WY14643 increased viral replication and caused lethality in mice. Unexpectedly, these effects proved independent of PPARα. We found that WY14643 suppressed production of type I interferon after MHV68 infection in vitro and in vivo. Taken together, our data indicate that caution should be employed when using PPARα agonists in immuno-metabolic studies, as they can have off-target effects on viral replication through the inhibition of type I interferon production. IMPORTANCE PPAR agonists are used clinically to treat both metabolic and inflammatory disorders. Because viruses are known to rewire host metabolism to their own benefit, the intersection of immunity, metabolism, and virology is an important research area. Our article is an important contribution to this field for two reasons. First, it shows a role for PPARα agonists in altering virus replication. Second, it shows that PPARα agonists can affect virus replication in a manner independent of their predicted target. This knowledge is valuable for anyone seeking to use PPARα agonists as a research tool.

Variants in ALDH1A2 reveal an anti-inflammatory role for retinoic acid and a new class of disease-modifying drugs in osteoarthritis

More than 40% of individuals will develop osteoarthritis (OA) during their lifetime, yet there are currently no licensed disease-modifying treatments for this disabling condition. Common polymorphic variants in ALDH1A2, which encodes the key enzyme for synthesis of all-trans retinoic acid (atRA), are associated with severe hand OA. Here, we sought to elucidate the biological significance of this association. We first confirmed that ALDH1A2 risk variants were associated with hand OA in the U.K. Biobank. Articular cartilage was acquired from 33 individuals with hand OA at the time of routine hand OA surgery. After stratification by genotype, RNA sequencing was performed. A reciprocal relationship between ALDH1A2 mRNA and inflammatory genes was observed. Articular cartilage injury up-regulated similar inflammatory genes by a process that we have previously termed mechanoflammation, which we believe is a primary driver of OA. Cartilage injury was also associated with a concomitant drop in atRA-inducible genes, which were used as a surrogate measure of cellular atRA concentration. Both responses to injury were reversed using talarozole, a retinoic acid metabolism blocking agent (RAMBA). Suppression of mechanoflammation by talarozole was mediated by a peroxisome proliferator-activated receptor gamma (PPARγ)-dependent mechanism. Talarozole was able to suppress mechano-inflammatory genes in articular cartilage in vivo 6 hours after mouse knee joint destabilization and reduced cartilage degradation and osteophyte formation after 26 days. These data show that boosting atRA suppresses mechanoflammation in the articular cartilage in vitro and in vivo and identifies RAMBAs as potential disease-modifying drugs for OA.

Peroxisome proliferator-activated receptor-γ as the gatekeeper of tight junction in Clostridioides difficile infection

Clostridioides difficile is a major causative pathogen of nosocomial antibiotic-associated diarrhea and severe colitis. Despite the use of vancomycin and fidaxomicin as standard drugs for the treatment of C. difficile infection (CDI), clinical relapse rates remain high. Therefore, new alternative therapeutics to treat CDI are urgently required. The nuclear receptor, peroxisome proliferator-activated receptor-γ (PPAR-γ), is mainly expressed in the adipose tissue and modulates lipid metabolism and insulin sensitization. Previous studies have shown that PPAR-γ is highly expressed in colonic tissues and regulates tight junction function in epithelial cells. However, the role of PPAR-γ in CDI pathogenesis remains unclear. In this study, we used a mouse model of CDI and found that both expression levels of PPAR-γ and the tight junction protein, occludin, were decreased in colonic tissues. Furthermore, to investigate the role of PPAR-γ in CDI, we used PPAR-γ defective mice and found that intestinal permeability and bacterial dissemination in these mice were significantly higher than those in wild-type mice during CDI. Administration of the PPAR-γ agonist, pioglitazone, to activate PPAR-γ activity improved the phenotypes of CDI, including bodyweight loss, inflammation, and intestinal integrity. Taken together, these results demonstrate that PPAR-γ is a potential therapeutic target in CDI, as it modulates colonic inflammation and integrity.

Alternatively Spliced Landscape of PPARγ mRNA in Podocytes Is Distinct from Adipose Tissue

Podocytes are highly differentiated epithelial cells, and their structural and functional integrity is compromised in a majority of glomerular and renal diseases, leading to proteinuria, chronic kidney disease, and kidney failure. Traditional agonists (e.g., pioglitazone) and selective modulators (e.g., GQ-16) of peroxisome-proliferator-activated-receptor-γ (PPARγ) reduce proteinuria in animal models of glomerular disease and protect podocytes from injury via PPARγ activation. This indicates a pivotal role for PPARγ in maintaining glomerular function through preservation of podocytes distinct from its well-understood role in driving insulin sensitivity and adipogenesis. While its transcriptional role in activating adipokines and adipogenic genes is well-established in adipose tissue, liver and muscle, understanding of podocyte PPARγ signaling remains limited. We performed a comprehensive analysis of PPARγ mRNA variants due to alternative splicing, in human podocytes and compared with adipose tissue. We found that podocytes express the ubiquitous PPARγ Var 1 (encoding γ1) and not Var2 (encoding γ2), which is mostly restricted to adipose tissue and liver. Additionally, we detected expression at very low level of Var4, and barely detectable levels of other variants, Var3, Var11, VartORF4 and Var9, in podocytes. Furthermore, a distinct podocyte vs. adipocyte PPAR-promoter-response-element containing gene expression, enrichment and pathway signature was observed, suggesting differential regulation by podocyte specific PPARγ1 variant, distinct from the adipocyte-specific γ2 variant. In summary, podocytes and glomeruli express several PPARγ variants, including Var1 (γ1) and excluding adipocyte-specific Var2 (γ2), which may have implications in podocyte specific signaling and pathophysiology. This suggests that that new selective PPARγ modulators can be potentially developed that will be able to distinguish between the two forms, γ1 and γ2, thus forming a basis of novel targeted therapeutic avenues.

Exercise-induced increase in M2 macrophages accelerates wound healing in young mice

Moderate-intensity exercise performed during wound healing has been reported to decrease inflammatory cytokines and chemokines and accelerate wound healing. However, its effect on macrophage phenotype and the mechanism by which exercise accelerates wound healing remain unclear. The purpose of this study was to investigate the effect of exercise on macrophage phenotype during wound healing and to clarify the relationship between angiogenesis and wound healing. 12-week-old male C57BL/6J mice were divided into sedentary (n = 6) and exercise groups (n = 6). The exercise group performed moderate-intensity treadmill running exercise (9.0 m/min, 60 min) for 10 days. Double immunofluorescence analysis was performed using F4/80+ inducible nitric oxide synthase (iNOS)+ for M1 macrophages, F4/80+ transforming growth factor-beta (TGF-β)1+ for M2 macrophages, and CD31+ alpha smooth muscle actin (α-SMA)+ for angiogenesis. The exercise group showed significantly accelerated wound healing compared with the sedentary group. From early wound healing onward, exercise significantly inhibited M1 macrophage infiltration and increased M2 macrophage count. Exercise also significantly increased angiogenesis. Furthermore, the M2 macrophage phenotype was significantly correlated with angiogenesis in the exercise group, indicating that M2 macrophages and angiogenesis are related to accelerated wound healing. These findings suggest that moderate-intensity exercise increases TGF-β1 derived from M2 macrophages, which may be associated with enhanced angiogenesis and wound healing in young mice.

Integrated biomarker responses in European seabass Dicentrarchus labrax (Linnaeus, 1758) chronically exposed to PVC microplastics

Few studies evaluated long-term effects of polyvinyl chloride (PVC) microplastics (MPs) ingestion in fish. The present study aimed to investigate the integrated biomarker responses in the liver and blood of 162 European seabass, Dicentrarchus labrax, exposed for 90 days to control, virgin and marine incubated PVC enriched diets (0.1 % w/w) under controlled laboratory condition. Enzymatic and tissue alterations, oxidative stress, gene expression alterations and genotoxicity were examined. Additives and environmental contaminants levels in PVC-MPs, control feed matrices and in seabass muscles were also detected. The results showed that the chronic exposure at environmentally realistic PVC-MPs concentrations in seabass, cause early warning signs of toxicological harm in liver by induction of oxidative stress, the histopathological alterations and also by the modulation of the Peroxisome proliferator-activated receptors (PPARs) and Estrogen receptor alpha (ER-α) genes expression. A trend of increase of DNA alterations and the observation of some neoformations attributable to lipomas suggest also genotoxic and cancerogenic effects of PVC. This investigation provides important data to understand the regulatory biological processes affected by PVC-MPs ingestion in marine organisms and may also support the interpretation of results provided by studies on wild species.

Palmitoylethanolamide and White Matter Lesions: Evidence for Therapeutic Implications

Palmitoylethanolamide (PEA), the naturally occurring amide of ethanolamine and palmitic acid, is an endogenous lipid compound endowed with a plethora of pharmacological functions, including analgesic, neuroprotective, immune-modulating, and anti-inflammatory effects. Although the properties of PEA were first characterized nearly 65 years ago, the identity of the receptor mediating these actions has long remained elusive, causing a period of research stasis. In the last two decades, a renewal of interest in PEA occurred, and a series of interesting studies have demonstrated the pharmacological properties of PEA and clarified its mechanisms of action. Recent findings showed the ability of formulations containing PEA in promoting oligodendrocyte differentiation, which represents the first step for the proper formation of myelin. This evidence opens new and promising research opportunities. White matter defects have been detected in a vast and heterogeneous group of diseases, including age-related neurodegenerative disorders. Here, we summarize the history and pharmacology of PEA and discuss its therapeutic potential in restoring white matter defects.

Novel insights into the regulation of cellular catabolic metabolism in macrophages through nuclear receptors

Regulation of cellular catabolic metabolism in immune cells has recently become a major concept for resolution of inflammation. Nuclear receptors (NRs), including peroxisome proliferator activator receptors (PPARs), 1,25-dihydroxyvitamin D(3) receptor (VDR), liver X receptors (LXRs), glucocorticoid receptors (GRs), estrogen-related receptor α (ERRα) and Nur77, have been identified as major modulators of inflammation, affecting innate immune cells, such as macrophages. Evidence emerges on how NRs regulate cellular metabolism in macrophages during inflammatory processes and contribute to the resolution of inflammation. This could have new implications for our understanding of how NRs shape immune responses and inform anti-inflammatory drug design. This review will highlight the recent developments about NRs and their role in cellular metabolism in macrophages.

A Cytological Atlas of the Human Liver Proteome from PROTEOMESKY-LIVERHu 2.0, a Publicly Available Database

The liver plays a unique role as a metabolic center of the body, and also performs other important functions such as detoxification and immune response. Here, we establish a cell type-resolved healthy human liver proteome including hepatocytes (HCs), hepatic stellate cells (HSCs), Kupffer cells (KCs), and liver sinusoidal endothelial cells (LSECs) by high-resolution mass spectrometry. Overall, we quantify total 8354 proteins for four cell types and over 6000 proteins for each cell type. Analysis of this data set and regulatory pathway reveals the cellular labor division in the human liver follows the pattern that parenchymal cells make the main components of pathways, but nonparenchymal cells trigger these pathways. Human liver cells show some novel molecular features: HCs maintain KCs and LSECs homeostasis by producing cholesterol and ketone bodies; HSCs participate in xenobiotics metabolism as an agent deliverer; KCs and LSECs mediate immune response through MHC class II-TLRs and MHC class I-TGFβ cascade, respectively; and KCs play a central role in diurnal rhythms regulation through sensing diurnal IGF and temperature flux. Together, this work expands our understandings of liver physiology and provides a useful resource for future analyses of normal and diseased livers.

Expression of toll like receptor 8 (TLR8) in specific groups of mouse hippocampal interneurons

Toll-like receptors (TLR) are one of the main constituents of the innate immune system in mammals. They can detect conserved microbial structures (pathogen-associated molecular patterns) and host-derived ligands that are produced during cellular stress and damage (danger-associated molecular patterns) and may then initiate an intracellular signaling cascade leading to the expression of pro-inflammatory cytokines and immediate immune responses. Some TLR (TLR1, 2, 4, 5, and 6) are expressed on the cell surface while others (TLR3, 7, 8 and 9) are present on the surface of endosomes and their ligands require internalization before recognition is possible. Several TLR have also been detected in neurons where they may serve functions that are not related to immune responses. TLR2, 3, and 4 have been described in cortical neurons and, for TLR4, a seizure-promoting role in epilepsies associated with inflammation has been shown. TLR3, 7, and 8 expressed in neurons seem to influence the growth or withdrawal of neurites and robust activation of TLR8 in neurons may even induce neuronal death. The goal of the current study was to investigate the expression of TLR8 in the hippocampus of mice during postnatal development and in adulthood. We focused on three functionally distinct groups of GABAergic interneurons characterized by the expression of the molecular markers parvalbumin, somatostatin, or calretinin, and we applied double fluorescence immunohistochemistry and cell counts to quantify co-expression of TLR8 in the three groups of GABA-interneurons across hippocampal subregions. We found subregion-specific differences in the expression of TLR8 in these interneurons. During postnatal development, TLR8 was detected only in mice older than P5. While only a small fraction of hippocampal calretinin-positive interneurons expressed TLR8, most parvalbumin-positive interneurons in all hippocampal subregions co-expressed TLR8. Somatostatin-positive interneurons co-expressing TLR8 were mainly present in hippocampal sector CA3 but rare in the dentate gyrus and CA1. High expression of TLR8 in parvalbumin-interneurons may contribute to their high vulnerability in human temporal lobe epilepsy.

Advances in PPARs Molecular Dynamics and Glitazones as a Repurposing Therapeutic Strategy through Mitochondrial Redox Dynamics against Neurodegeneration

Peroxisome proliferator-activated receptors (PPARs) activity has significant implications for the development of novel therapeutic modalities against neurodegenerative diseases. Although PPAR-α, PPAR-β/δ, and PPAR-γ nuclear receptor expressions are significantly reported in the brain, their implications in brain physiology and other neurodegenerative diseases still require extensive studies. PPAR signaling can modulate various cell signaling mechanisms involved in the cells contributing to on- and off-target actions selectively to promote therapeutic effects as well as the adverse effects of PPAR ligands. Both natural and synthetic ligands for the PPARα, PPARγ, and PPARβ/δ have been reported. PPARα (WY 14.643) and PPARγ agonists can confer neuroprotection by modulating mitochondrial dynamics through the redox system. The pharmacological effect of these agonists may deliver effective clinical responses by protecting vulnerable neurons from Aβ toxicity in Alzheimer's disease (AD) patients. Therefore, the current review delineated the ligands' interaction with 3D-PPARs to modulate neuroprotection, and also deciphered the efficacy of numerous drugs, viz. Aβ aggregation inhibitors, vaccines, and γ-secretase inhibitors against AD; this review elucidated the role of PPAR and their receptor isoforms in neural systems, and neurodegeneration in human beings. Further, we have substantially discussed the efficacy of PPREs as potent transcription factors in the brain, and the role of PPAR agonists in neurotransmission, PPAR gamma coactivator-1α (PGC-1α) and mitochondrial dynamics in neuroprotection during AD conditions. This review concludes with the statement that the development of novel PPARs agonists may benefit patients with neurodegeneration, mainly AD patients, which may help mitigate the pathophysiology of dementia, subsequently improving overall the patient's quality of life.

Polyphenols Extracts from Oil Production Waste Products (OPWPs) Reduce Cell Viability and Exert Anti-Inflammatory Activity via PPARγ Induction in Colorectal Cancer Cells

Olive oil production is associated with the generation of oil production waste products (OPWPs) rich in water-soluble polyphenols that represent serious environmental problems. Yet OPWPs can offer new opportunities by exploiting their bioactive properties. In this study, we chemically characterized OPWPs polyphenolic extracts and investigated their biological activities in normal and colorectal cancer cells. Hydroxytyrosol (HTyr), the major constituent of these extracts, was used as the control. We show that both HTyr and the extracts affect cell viability by inducing apoptosis and cell cycle arrest. They downregulate inflammation by impairing NF-κB phosphorylation and expression of responsive cytokine genes, as TNF-α and IL-8, at both mRNA and protein levels, and prevent any further increase elicited by external challenges. Mechanistically, HTyr and the extracts activate PPARγ while hampering pro-inflammatory genes expression, acting as a specific agonist, likely through a trans-repression process. Altogether, OPWPs polyphenolic extracts show stronger effects than HTyr, conceivably due to additive or synergistic effects of all polyphenols contained. They display anti-inflammatory properties and these results may pave the way for improving OPWPs extraction and enrichment methods to reduce the environmental impact and support their use to ameliorate the inflammation associated with diseases and tumors.

PCK1 dysregulation in cancer: Metabolic reprogramming, oncogenic activation, and therapeutic opportunities

The last few decades have witnessed an advancement in our understanding of multiple cancer cell pathways related to metabolic reprogramming. One of the most important cancer hallmarks, including aerobic glycolysis (the Warburg effect), the central carbon pathway, and multiple-branch metabolic pathway remodeling, enables tumor growth, progression, and metastasis. Phosphoenolpyruvate carboxykinase 1 (PCK1), a key rate-limiting enzyme in gluconeogenesis, catalyzes the conversion of oxaloacetate to phosphoenolpyruvate. PCK1 expression in gluconeogenic tissues is tightly regulated during fasting. In tumor cells, PCK1 is regulated in a cell-autonomous manner rather than by hormones or nutrients in the extracellular environment. Interestingly, PCK1 has an anti-oncogenic role in gluconeogenic organs (the liver and kidneys), but a tumor-promoting role in cancers arising from non-gluconeogenic organs. Recent studies have revealed that PCK1 has metabolic and non-metabolic roles in multiple signaling networks linking metabolic and oncogenic pathways. Aberrant PCK1 expression results in the activation of oncogenic pathways, accompanied by metabolic reprogramming, to maintain tumorigenesis. In this review, we summarize the mechanisms underlying PCK1 expression and regulation, and clarify the crosstalk between aberrant PCK1 expression, metabolic rewiring, and signaling pathway activation. In addition, we highlight the clinical relevance of PCK1 and its value as a putative cancer therapeutic target.