Peroxisome Proliferator-Activated Receptors as a Therapeutic Target in Asthma

Integration of metabolomics and transcriptomics to reveal the mechanism of Gerberae piloselloidis herba in alleviating bronchial asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Gerberae Piloselloides Herba (GPH) is derived from Gerbera piloselloides (Linn.) Cass. It is a commonly used traditional medicine in China, featured by its special bioactivities as antitussive, expectorant, anti-asthma, anti-bacterial and anti-tumor. It is often used as an effective treatment for cough and sore throat as well as bronchial asthma (BA) in China. It was demonstrated in our previous studies that GPH exerted significant effects on the treatment of BA, but its underlying mechanism remains unclear.

AIM OF THE STUDY

This study was aimed at revealing the mechanism through which GPH protects against BA.

MATERIALS AND METHODS

The protective effect of GPH against BA was evaluated in a mouse model of BA induced by ovalbumin. Through integrated metabolomics and transcriptomics analysis, the most critical pathways were discovered. The effects of GPH in regulating these pathways was verified through molecular biology experiments and molecular docking.

RESULTS

GPH have anti-BA effects. In plasma and lung tissue, 5 and 17 differentially expressed metabolites (DEMs), respectively, showed a reversed tendency in the GPH group compared with the model group; apart from gamma-aminobutyric acid and butyrylcarnitine, these DEMs might aid in BA diagnosis. The DEMs were involved primarily in the regulation of lipid metabolism, followed by glucose metabolism and amino acid metabolism. Transcriptomic analysis indicated that GPH modulated 268 differentially expressed genes (DEGs). Integration analysis of metabolomics and transcriptomics revealed that GPH might regulate the PPAR signaling pathway, thus affecting the expression of key gene targets such as Cyp4a12a, Cyp4a12b, Adh7, Acaa1b and Gpat2; controlling fatty acid degradation, unsaturated fatty acid biosynthesis, glycerophospholipid metabolism and other lipid metabolic pathways; and ameliorating BA. This possibility was confirmed through reverse-transcription quantitative polymerase chain reaction, western blotting, immunofluorescence and molecular docking.

CONCLUSION

GPH was found to activate the PPAR signaling pathway, decrease the levels of Cyp4a12a and Cyp4a12b, and increase the levels of Adh7, Acaa1b and Gpat2, thereby regulating lipid metabolism disorder, decreasing the generation of inflammatory mediators and limiting lung injury.

Pathophysiology and Clinical Management of Dyslipidemia in People Living with HIV: Sailing through Rough Seas

Infections with human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) represent one of the greatest health burdens worldwide. The complex pathophysiological pathways that link highly active antiretroviral therapy (HAART) and HIV infection per se with dyslipidemia make the management of lipid disorders and the subsequent increase in cardiovascular risk essential for the treatment of people living with HIV (PLHIV). Amongst HAART regimens, darunavir and atazanavir, tenofovir disoproxil fumarate, nevirapine, rilpivirine, and especially integrase inhibitors have demonstrated the most favorable lipid profile, emerging as sustainable options in HAART substitution. To this day, statins remain the cornerstone pharmacotherapy for dyslipidemia in PLHIV, although important drug-drug interactions with different HAART agents should be taken into account upon treatment initiation. For those intolerant or not meeting therapeutic goals, the addition of ezetimibe, PCSK9, bempedoic acid, fibrates, or fish oils should also be considered. This review summarizes the current literature on the multifactorial etiology and intricate pathophysiology of hyperlipidemia in PLHIV, with an emphasis on the role of different HAART agents, while also providing valuable insights into potential switching strategies and therapeutic options.

Improvement of inhaled paraquat induced lung and systemic inflammation, oxidative stress and memory changes by safranal

The effects of safranal and pioglitazone alone and their combination on inhaled paraquat (PQ)-induced systemic oxidative stress and inflammation as well as behavioral changes were examined in rats. In this study, animals were exposed to saline (Ctrl) or PQ (PQ groups) aerosols. PQ exposed animals were treated with dexamethasone, 0.8 and 3.2 mg/kg/day safranal (Saf-L and Saf-H), 5 mg/kg/day pioglitazone (Pio), and Saf-L + Pio for 16 days during PQ exposure period. PQ group showed increased numbers of total and differential WBCs in blood and bronchoalveolar lavage fluid (BALF), increased malondialdehyde (MDA), in the serum BALF and brain reduced thiol, catalase (CAT), and superoxide dismutase (SOD) levels compared to the control group (for all, p < 0.001). The escape latency and traveled distance were enhanced, but the time spent in the target quadrant in the probe day and the latency to enter the dark room 3, 24, 48, and 72 h after receiving an electrical shock, (in the shuttle box test) were decreased in the PQ group (p < 0.05 to P < 0.001). In all treated groups, all measure values were improved compared to PQ group (p < 0.05 to p < 0.001). In combination treated group of Saf-L + Pio, most measured values were more improved than the Saf-L and Pio groups (p < 0.05 to p < 0.001). Saf and Pio improved PQ-induced changes similar to dexamethasone but the effects produced by combination treatments of Saf-L + Pio were more prominent than Pio and Saf-L alone, suggesting a potentiating effect for the combination of the two agents.

Proanthocyanidin Alleviates Liver Ischemia/Reperfusion Injury by Suppressing Autophagy and Apoptosis via the PPARα/PGC1α Signaling Pathway

Background and Aims

Hepatic ischemia-reperfusion injury (IRI) is a common pathophysiological phenomenon in clinical practice, which usually occurs in liver transplantation, liver resection, severe trauma, and hemorrhagic shock. Proanthocyanidin (PC), exerted from various plants with antioxidant, antitumor, and antiaging activity, were administrated in our study to investigate the underlying mechanism of its protective function on IRI.

Methods

Two doses of PC (50 mg/kg, 100 mg/kg) were given to BALB/c mice by intragastric administration for 7 days before partial (70%) warm IR surgery. Serum and liver tissues were collected 2, 8, and 24 h after reperfusion for relevant experiments.

Results

The results of transaminase and hematoxylin and eosin staining indicated that PC pretreatment significantly alleviated IRI in mice. Serum total superoxide dismutase increased and malondialdehyde decreased in PC pretreatment groups. Enzyme-linked immunosorbent assays, western blotting, quantitative real-time polymerase chain reaction, and immunohistochemistry showed that inflammation, apoptosis, and autophagy in PC preprocessing groups were significantly inhibited and were dose-dependent. The protein, mRNA expression, and immunohistochemical staining results of peroxisome proliferator-activated receptor alpha (PPARα) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) in the PC pretreatment groups were significantly upregulated compared with the IR group in a dose-dependent manner.

Conclusions

PC pretreatment suppressed inflammation, apoptosis, and autophagy via the PPAR-α signaling pathway to protect against IRI of the liver in mice.

Metabolic and Genetic Association of Vitamin D with Calcium Signaling and Insulin Resistance

Various evidences have unveiled the significance of Vitamin D in diverse processes which include its action in prevention of immune dysfunction, cancer and cardiometabolic disorders. Studies have confirmed the function of VD in controlling the expression of approximately nine hundred genes including gene expression of insulin. VD insufficiency may be linked with the pathogenesis of diseases that are associated with insulin resistance (IR) including diabetes as well as obesity. Thus, VD lowers IR-related disorders such as inflammation and oxidative stress. This review provides an insight regarding the molecular mechanism manifesting, how insufficiency of VD may be connected with the IR and diabetes. It also discusses the effect of VD in maintaining the Ca2+ levels in beta cells of the pancreas and in the tissues that are responsive to insulin.

Potential for repurposing oral hypertension/diabetes drugs to decrease asthma risk in obesity

OBJECTIVE

Risk for asthma in the overweight/obese may be mediated by adiponectin and peroxisome proliferator activated receptor pathways and may be reduced by the use of oral drugs impacting these pathways, such as angiotensin converting enzyme inhibitors (ACE-I), thiazolidinediones (TZD), and angiotensin receptor blockers (ARB). Our study objective was to determine whether ACE-I, TZD, and/or ARB use in overweight/obese adults with diabetes mellitus and/or hypertension is associated with a lower risk for incident asthma.

METHODS

Using an existing cohort of American veterans, we performed a longitudinal data analysis over 15 years. Exposure was defined by the prescription pickup of ACE-I, TZD, and/or ARB for at least 4 weeks. The outcome, time until new-onset of clinician-diagnosed asthma, was studied using survival analysis. The propensity scoring method controlled for treatment selection bias.

RESULTS

2.83 million eligible veterans, including 77,278 with incident asthma, were studied. As compared to those unexposed, the use of ACE-I alone, TZD alone, or their combinations were each associated with decreased risk for incident asthma (hazard ratios of 0.88, 0.74, and 0.20, respectively; p < 0.001 for all analyses in the fully adjusted statistical models). TZD lowered the risk among racial/ethnic minority subjects more than among White participants (p < 0.001). On the other hand, ARB use alone or in combination with TZD was associated with a higher risk for incident asthma.

CONCLUSIONS

Use of ACE-I and/or TZD was associated with a lower risk for incident asthma in overweight/obese patients with diabetes mellitus and/or hypertension.

Anti-Inflammatory Effects of Lipid-Lowering Drugs and Supplements-A Narrative Review

Cardiovascular diseases (CVD) are the leading cause of death worldwide. Since the establishment of the "lipid hypothesis", according to which, cholesterol level is directly correlated to the risk of CVD, many different lipid-lowering agents have been introduced in clinical practice. A majority of these drugs, in addition to their lipid-lowering properties, may also exhibit some anti-inflammatory and immunomodulatory activities. This hypothesis was based on the observation that a decrease in lipid levels occurs along with a decrease in inflammation. Insufficient reduction in the inflammation during treatment with lipid-lowering drugs could be one of the explanations for treatment failure and recurrent CVD events. Thus, the aim of this narrative review was to evaluate the anti-inflammatory properties of currently available lipid-lowering medications including statins, ezetimibe, bile acid sequestrants (BAS), proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, fibrates, omega-3 fatty acids, and niacin, as well as dietary supplements and novel drugs used in modern times.

Epigenome-Wide Association Studies of the Fractional Exhaled Nitric Oxide and Bronchodilator Drug Response in Moderate-to-Severe Pediatric Asthma

Asthma is the most prevalent pediatric chronic disease. Bronchodilator drug response (BDR) and fractional exhaled nitric oxide (FeNO) are clinical biomarkers of asthma. Although DNA methylation (DNAm) contributes to asthma pathogenesis, the influence of DNAm on BDR and FeNO is scarcely investigated. This study aims to identify DNAm markers in whole blood associated either with BDR or FeNO in pediatric asthma. We analyzed 121 samples from children with moderate-to-severe asthma. The association of genome-wide DNAm with BDR and FeNO has been assessed using regression models, adjusting for age, sex, ancestry, and tissue heterogeneity. Cross-tissue validation was assessed in 50 nasal samples. Differentially methylated regions (DMRs) and enrichment in traits and biological pathways were assessed. A false discovery rate (FDR) < 0.1 and a genome-wide significance threshold of p < 9 × 10−8 were used to control for false-positive results. The CpG cg12835256 (PLA2G12A) was genome-wide associated with FeNO in blood samples (coefficient= −0.015, p = 2.53 × 10−9) and nominally associated in nasal samples (coefficient = −0.015, p = 0.045). Additionally, three CpGs were suggestively associated with BDR (FDR < 0.1). We identified 12 and four DMRs associated with FeNO and BDR (FDR < 0.05), respectively. An enrichment in allergic and inflammatory processes, smoking, and aging was observed. We reported novel associations of DNAm markers associated with BDR and FeNO enriched in asthma-related processes.

Associations Of Fatty Acid Composition In Leukocyte Membranes With Systemic Inflammation In Chronic Obstructive Pulmonary Disease Progression

Background — The development of systemic inflammation is a key pathogenetic mechanism in progression of chronic obstructive pulmonary disease (COPD). Fatty acids (FAs) and their oxidized derivatives serve as essential regulators of inflammation. The relationship between systemic inflammation and FA metabolism in COPD is poorly understood. In our research, we focused on examining the FA composition of the leukocyte membrane in COPD and the FA metabolism in association with systemic inflammation. Objective — We examined 137 patients with mild, moderate, or severe COPD. The control group comprised 32 healthy non-smokers. Methods — Blood cytokines and immune cell subpopulations were evaluated by flow cytometry. The FA composition of the leukocyte membranes was analyzed by gas chromatography. The concentrations of eicosanoids (thromboxane B2 (TXB2), leukotriene B4 (LTB4)) in plasma were measured by ELISA. Results — Our results implied systemic inflammation in all patients with COPD. The analysis of the FA composition of leukocyte membrane demonstrated increased level of saturated FAs and n-6 polyunsaturated fatty acids (PUFAs), along with reduced levels of monounsaturated FAs and n-3 PUFAs, in patients with COPD. The TXB2 and LTB4 content was increasing in COPD patients. We established a significant correlation with n-6 PUFAs, immune cells, and cytokines, which was indicative of an important role of FAs in the progress of systemic inflammation in COPD. Conclusion — Thus, FA modification of immune cells in patients with chronic pathologies of the bronchopulmonary system leads not only to disruption of the cell membrane structure, but also to the pathology of immune response regulation, and contributes to the development of the inflammatory process. The latter is a decisive factor in the pathogenesis of COPD.

Transcriptome analysis of sputum cells reveals two distinct molecular phenotypes of “asthma and chronic obstructive pulmonary disease overlap” in the elderly

Background

Little is known about the pathogenesis of asthma and chronic obstructive pulmonary disease (COPD) overlap (ACO). This study examined the molecular phenotypes of ACO in the elderly.

Methods

A genome-wide investigation of gene expression in sputum cells from the elderly with asthma, ACO, or COPD was performed using gene set variation analysis (GSVA) with predefined asthma- or COPD-specific gene signatures. We then performed a subsequent cluster analysis using enrichment scores (ESs) to identify molecular clusters in the elderly with ACO. Finally, a second GSVA was conducted with curated gene signatures to gain insight into the pathogenesis of ACO associated with the identified molecular clusters.

Results

Seventy elderly individuals were enrolled (17 with asthma, 41 with ACO, and 12 with COPD). Two distinct molecular clusters of ACO were identified. Clinically, ACO cluster 1 (N = 23) was characterized by male and smoker dominance, more obstructive lung function, and higher proportions of both neutrophil and eosinophil in induced sputum compared to ACO cluster 2 (N = 18). ACO cluster 1 had molecular features similar to both asthma and COPD, with mitochondria and peroxisome dysfunction as important mechanisms in the pathogenesis of these diseases. The molecular features of ACO cluster 2 differed from those of asthma and COPD, with enhanced innate immune reactions to microorganisms identified as being important in the pathogenesis of this form of ACO.

Conclusion

Recognition of the unique biological pathways associated with the two distinct molecular phenotypes of ACO will deepen our understanding of ACO in the elderly.

Proline metabolism reprogramming of trained macrophages induced by early respiratory infection combined with allergen sensitization contributes to development of allergic asthma in childhood of mice

Background

Infants with respiratory syncytial virus (RSV)-associated bronchiolitis are at increased risk of childhood asthma. Recent studies demonstrated that certain infections induce innate immune memory (also termed trained immunity), especially in macrophages, to respond more strongly to future stimuli with broad specificity, involving in human inflammatory diseases. Metabolic reprogramming increases the capacity of the innate immune cells to respond to a secondary stimulation, is a crucial step for the induction of trained immunity. We hypothesize that specific metabolic reprogramming of lung trained macrophages induced by neonatal respiratory infection is crucial for childhood allergic asthma.

Objective

To address the role of metabolic reprogramming in lung trained macrophages induced by respiratory virus infection in allergic asthma.

Methods

Neonatal mice were infected and sensitized by the natural rodent pathogen Pneumonia virus of mice (PVM), a mouse equivalent strain of human RSV, combined with ovalbumin (OVA). Lung CD11b⁺ macrophages in the memory phase were re-stimulated to investigate trained immunity and metabonomics. Adoptive transfer, metabolic inhibitor and restore experiments were used to explore the role of specific metabolic reprogramming in childhood allergic asthma.

Results

PVM infection combined with OVA sensitization in neonatal mice resulted in non-Th2 (Th1/Th17) type allergic asthma following OVA challenge in childhood of mice. Lung CD11b⁺ macrophages in the memory phage increased, and showed enhanced inflammatory responses following re-stimulation, suggesting trained macrophages. Adoptive transfer of the trained macrophages mediated the allergic asthma in childhood. The trained macrophages showed metabolic reprogramming after re-stimulation. Notably, proline biosynthesis remarkably increased. Inhibition of proline biosynthesis suppressed the development of the trained macrophages as well as the Th1/Th17 type allergic asthma, while supplement of proline recovered the trained macrophages as well as the allergic asthma.

Conclusion

Proline metabolism reprogramming of trained macrophages induced by early respiratory infection combined with allergen sensitization contributes to development of allergic asthma in childhood. Proline metabolism could be a well target for prevention of allergic asthma in childhood.

Subtyping children with asthma by clustering analysis of mRNA expression data

Background: Asthma is a heterogeneous disease. There are several phenotypic classifications for childhood asthma.

Methods: Unsupervised consensus cluster analysis was used to classify 36 children with persistent asthma from the GSE65204 dataset. The differentially expressed genes (DEGs) between different asthma subtypes were identified, and weighted gene co-expression network analysis (WGCNA) was carried out. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis was performed for DEGs and critical gene modules. Protein–protein interactions (PPI) were constructed to obtain the hub genes. Finally, differences in the immune microenvironment were analyzed between different subtypes.

Results: Two subtypes (C1, C2) were identified using unsupervised consensus clustering. The DEGs between different asthma subtypes were mainly enriched in immune regulation and the release of inflammatory mediators. The important modular genes screened by WGCNA were mainly enriched in aspects of inflammatory mediator regulation. PPI analysis found 10 hub genes (DRC1, TTC25, DNALI1, DNAI1, DNAI2, PIH1D3, ARMC4, RSPH1, DNAAF3, and DNAH5), and ROC analysis demonstrated that 10 hub genes had a reliably ability to distinguish C1 from C2. And we observed differences between C1 and C2 in their immune microenvironment.

Conclusion: Using the gene expression profiles of children’s nasal epithelium, we identified two asthma subtypes that have different gene expression patterns, biological characteristics, and immune microenvironments. This will provide a reference point for future childhood asthma typing and personalized therapy.

Brain-Derived Neurotrophic Factor And Coronary Artery Disease

Coronary artery disease (CAD) is defined as myocardial damage developing as a result of its organic and functional changes, and leading to impaired blood flow through the coronary arteries. An important pathogenetic component of CAD is atherosclerosis. Currently, key aspects of the molecular relationship between inflammation and atherosclerosis are being actively studied, the immunometabolic theory of atherosclerosis is being discussed, along with an involvement of perivascular adipose tissue in the pathogenesis of this pathology, due to its ability to respond to atherogenic stimuli via developing inflammatory reactions. Evidence has been accumulated that in patients with CAD, both in their blood and perivascular adipose tissue, the level of neurotrophic factors (in particular, brain-derived neurotrophic factor, BDNF) changes, which may be a promising area of research from the standpoint of studying this factor as a therapeutic target for atherosclerosis in CAD. Neurotrophic growth factors control the functioning of both immune and nervous systems, and the balance of energy metabolism and innervation of adipose tissue. They affect vascular homeostasis, and are also involved in causing and stopping inflammation. Currently, there are data on the role of BDNF in the pathogenesis of cardiovascular, neurodegenerative and metabolic diseases, and on the effect of polyunsaturated fatty acids and eicosanoids on the level of BDNF and, accordingly, the development and progression of coronary artery atherosclerosis. Our review summarizes published data (2019-2021) on the pathophysiological and pathogenetic mechanisms of the relationship between BDNF and CAD (atherosclerosis).

[Fatty acid epoxides in the regulation of the inflammation]

Cyclooxygenase and lipoxygenase derived lipid metabolites of polyunsaturated fatty acids (PUFAs), as well as their role in the inflammation, have been studied quite thoroughly. However, cytochrome P450 derived lipid mediators, as well as their participation in the regulation of the inflammation, need deeper understanding. In recent years, it has become known that PUFAs are oxidized by cytochrome P450 epoxygenases to epoxy fatty acids, which act as the extremely powerful lipid mediators involved in resolving inflammation. Recent studies have shown that the anti-inflammatory mechanisms of ω-3 PUFAs are also mediated by their conversion to the endocannabinoid epoxides. Thus, it is clear that a number of therapeutically relevant functions of PUFAs are due to their conversion to PUFA epoxides. However, with the participation of cytochrome P450 epoxygenases, not only PUFA epoxides, but also other metabolites are formed. They are further are converted by epoxide hydrolases into pro-inflammatory dihydroxy fatty acids and anti-inflammatory dihydroxyeicosatrienoic acids. The study of the role of PUFA epoxides in the regulation of the inflammation and pharmacological modeling of the activity of epoxide hydrolases are the promising strategies for the treatment of the inflammatory diseases. This review systematizes the current literature data of the fatty acid epoxides, in particular, the endocannabinoid epoxides. Their role in the regulation of inflammation is discussed.

Lipid Behavior in Metabolic Syndrome Pathophysiology

Undeniably, lipid plays an extremely important role in the homeostasis balance since lipid contributes to the regulation of the metabolic processes. The metabolic syndrome pathogenesis is multi-pathway that composes neurohormonal disorders, endothelial cell dysfunction, metabolic disturbance, genetic predisposition, in addition to gut commensal microbiota. The heterogenicity of the possible mechanisms gives the metabolic syndrome its complexity and limitation of therapeutic accesses. The main pathological link is that lipid contributes to the emergence of metabolic syndrome via central obesity and visceral obesity that consequently lead to oxidative stress and chronic inflammatory response promotion. Physiologically, a balance is kept between the adiponectin and adipokines levels to maintain the lipid level in the organism. Clinically, extremely important to define the borders of the lipid level in which the pathogenesis of the metabolic syndrome is reversible, otherwise it will be accompanied by irreversible complications and sequelae of the metabolic syndrome (cardiovascular, insulin resistance). The present paper is dedicated to providing novel insights into the role of lipid in the development of metabolic syndrome; hence dyslipidemia is the initiator of insulin resistance syndrome (metabolic syndrome).

The microvascular hypothesis underlying neurologic manifestations of long COVID-19 and possible therapeutic strategies

With the ongoing distribution of the coronavirus disease (COVID) vaccines, the pandemic of our age is ending, leaving the world to deal with its well-documented aftereffects. Long COVID comprises a variety of symptoms, of which the neurological component prevails. The most permeating theory on the genesis of these symptoms builds upon the development of microvascular dysfunction similar to that seen in numerous vascular diseases such as diabetes. This can occur through the peripheral activation of angiotensin-converting enzyme 2 receptors, or through exacerbations of pro-inflammatory cytokines that can remain in circulation even after the infection diminishes. Several drugs have been identified to act on the neurovascular unit to promote repair, such as gliptins, and others. They also succeeded in improving neurologic outcome in diabetic patients. The repurposing of such drugs for treatment of long COVID-19 can possibly shorten the time to recovery of long COVID-19 syndrome.

What's the deal with efferocytosis and asthma?

Mucosal sites, such as the lung, serve as crucial, yet vulnerable barriers to environmental insults such as pathogens, allergens, and toxins. Often, these exposures induce massive infiltration and death of short-lived immune cells in the lung, and efficient clearance of these cells is important for preventing hyperinflammation and resolving immunopathology. Herein, we review recent advances in our understanding of efferocytosis, a process whereby phagocytes clear dead cells in a noninflammatory manner. We further discuss how efferocytosis impacts the onset and severity of asthma in humans and mammalian animal models of disease. Finally, we explore how recently identified genetic perturbations or biological pathway modulations affect pathogenesis and shed light on novel therapies aimed at treating or preventing asthma.

Development of mode of action networks related to the potential role of PPARγ in respiratory diseases

The peroxisome proliferator-activated receptor γ (PPARγ) is a key transcription factor, operating at the intercept of metabolic control and immunomodulation. It is ubiquitously expressed in multiple tissues and organs, including lungs. There is a growing body of information supporting the role of PPARγ signalling in respiratory diseases. The aim of the present study was to develop mode of action (MoA) networks reflecting the relationships between PPARγ signalling and the progression/alleviation of a spectrum of lung pathologies. Data mining was performed using the resources of the NIH PubMed and PubChem information systems. By linking available data on pathological/therapeutic effects of PPARγ modulation, knowledge-based MoA networking at different levels of biological organization (molecular, cellular, tissue, organ, and system) was performed. Multiple MoA networks were developed to relate PPARγ modulation to the progress or the alleviation of pulmonary disorders, triggered by diverse pathogenic, genetic, chemical, or mechanical factors. Pharmacological targeting of PPARγ signalling was discussed with regard to ligand- and cell type-specific effects in the context of distinct disease inductor- and disease stage-dependent patterns. The proposed MoA networking analysis allows for a better understanding of the potential role of PPARγ modulation in lung pathologies. It presents a mechanistically justified basis for further computational, experimental, and clinical monitoring studies on the dynamic control of PPARγ signalling in respiratory diseases.

Cross-Linking Cellular Prion Protein Induces Neuronal Type 2-Like Hypersensitivity

Background

Previous reports identified proteins associated with ‘apoptosis’ following cross-linking PrP^C with motif-specific anti-PrP antibodies in vivo and in vitro. The molecular mechanisms underlying this IgG-mediated neurotoxicity and the role of the activated proteins in the apoptotic pathways leading to neuronal death has not been properly defined. Previous reports implicated a number of proteins, including apolipoprotein E, cytoplasmic phospholipase A2, prostaglandin and calpain with anti-PrP antibody-mediated ‘apoptosis’, however, these proteins are also known to play an important role in allergy. In this study, we investigated whether cross-linking PrP^C with anti-PrP antibodies stimulates a neuronal allergenic response.

Methods

Initially, we predicted the allergenicity of the epitope sequences associated with ‘neurotoxic’ anti-PrP antibodies using allergenicity prediction servers. We then investigated whether anti-PrP antibody treatment of mouse primary neurons (MPN), neuroblastoma cells (N2a) and microglia (N11) cell lines lead to a neuronal allergenic response.

Results

In-Silico studies showed that both tail- and globular-epitopes were allergenic. Specifically, binding regions that contain epitopes for previously reported ‘neurotoxic’ antibodies such as ICSM18 (146-159), ICSM35 (91-110), POM 1 (138-147) and POM 3 (95-100) lead to activation of allergenic related proteins. Following direct application of anti-PrP^C antibodies on N2a cells, we identified 4 neuronal allergenic-related proteins when compared with untreated cells. Furthermore, we identified 8 neuronal allergenic-related proteins following treatment of N11 cells with anti-PrP^C antibodies prior to co-culture with N2a cells when compared with untreated cells. Antibody treatment of MPN or MPN co-cultured with antibody-treated N11 led to identifying 10 and 7 allergenic-related proteins when compared with untreated cells. However, comparison with 3F4 antibody treatment revealed 5 and 4 allergenic-related proteins respectively. Of importance, we showed that the allergenic effects triggered by the anti-PrP antibodies were more potent when antibody-treated microglia were co-cultured with the neuroblastoma cell line. Finally, co-culture of N2a or MPN with N11-treated with anti-PrP antibodies resulted in significant accumulation of NO and IL6 but not TNF-α in the cell culture media supernatant.

Conclusions

This study showed for the first time that anti-PrP antibody binding to PrP^C triggers a neuronal hypersensitivity response and highlights the important role of microglia in triggering an IgG-mediated neuronal hypersensitivity response. Moreover, this study provides an important impetus for including allergenic assessment of therapeutic antibodies for neurodegenerative disorders to derive safe and targeted biotherapeutics.

Thermosensory Transient Receptor Potential Ion Channels and Asthma

Asthma is a widespread chronic disease of the bronchopulmonary system with a heterogeneous course due to the complex etiopathogenesis. Natural-climatic and anthropogenic factors play an important role in the development and progression of this pathology. The reception of physical and chemical environmental stimuli and the regulation of body temperature are mediated by thermosensory channels, members of a subfamily of transient receptor potential (TRP) ion channels. It has been found that genes encoding vanilloid, ankyrin, and melastatin TRP channels are involved in the development of some asthma phenotypes and in the formation of exacerbations of this pathology. The review summarizes modern views on the role of high and low temperatures in airway inflammation in asthma. The participation of thermosensory TRP channels (vanilloid, ankyrin, and melastatin TRP channels) in the reaction to high and low temperatures and air humidity as well as in the formation of bronchial hyperreactivity and respiratory symptoms accompanying asthma is described. The genetic aspects of the functioning of thermosensory TRP channels are discussed. It is shown that new methods of treatment of asthma exacerbations caused by the influence of temperature and humidity should be based on the regulation of channel activity.

PPARγ Plays an Important Role in Acute Hepatic Ischemia-Reperfusion Injury via AMPK/mTOR Pathway

Background

Hepatic ischemia-reperfusion (IR) injury is one of the severe complications associated with liver surgery and leads to liver dysfunction. PPARγ is always linked with various physiologic pathways, and it can alleviate liver damage in IR injury.

Aim

In this study, we explored the potential mechanism of PPARγ in the pathogenesis of hepatic IR injury by mice model.

Methods

After treated with si-PPARγ or rosiglitazone, mice were subjected to hepatic ischemia-reperfusion. Liver tissue and blood samples were collected to evaluate liver injury and detected relative mRNA and protein expressions.

Results

The expression of PPARγ was increased after reperfusion. And the alleviation of PPARγ aggravated the liver damage in IR; at the same time, upregulation of the expression of PPARγ released the liver damage. And these effects of PPARγ in IR were related to the AMPK/mTOR/autophagy signaling pathway.

Conclusion

PPARγ plays an important role in hepatic IR injury at least partly via the AMPK/mTOR/autophagy pathway.

The Agonists of Peroxisome Proliferator-Activated Receptor-γ for Liver Fibrosis

Liver fibrosis is a common link in the transformation of acute and chronic liver diseases to cirrhosis. It is of great clinical significance to study the factors associated with the induction of liver fibrosis and elucidate the method of reversal. Peroxisome proliferator-activated receptors (PPARs) are a class of nuclear transcription factors that can be activated by peroxisome proliferators. PPARs play an important role in fibrosis of various organs, especially the liver, by regulating downstream targeted pathways, such as TGF-β, MAPKs, and NF-κB p65. In recent years, the development and screening of PPAR-γ ligands have become a focus of research. The PPAR-γ ligands include synthetic hypolipidemic and antidiabetic drugs. In addition, microRNAs, lncRNAs, circRNAs and nano new drugs have attracted research interest. In this paper, the research progress of PPAR-γ in the pathogenesis and treatment of liver fibrosis was discussed based on the relevant literature in recent years.

An inflammatory triangle in Sarcoidosis: PPAR-γ, immune microenvironment, and inflammation

INTRODUCTION

Sarcoidosis is an inflammatory disorder characterized by granuloma formation in several organs. Sarcoidosis patients experience higher inflammatory responses resulting in pulmonary fibrosis. Although the precise mechanisms have not been well elucidated, the relationship between the immune system activation and inflammatory status is pivotal in the pathogenesis of sarcoidosis.

AREAS COVERED

Peroxisome proliferator-activated receptor (PPAR) includes the transcription factors involved in cell metabolism, proliferation, and immune response. In the alveolar macrophages of patients with sarcoidosis, the reduced activity and a decreased level of PPAR-γ have been shown. In this study, we discuss how reducing the level of PPAR-γ could lead to increased inflammation and immune responses in patients with sarcoidosis.

EXPERT OPINION

Lack of PPAR-γ may contribute to the development of a suitable milieu for the formation of immune-associated pulmonary granuloma. Reduced levels of PPAR-γ in sarcoidosis could result from over-activation of the immune system and elevated inflammatory responses, as well. Due to the anti-inflammatory function of PPAR-γ, identifying the relation between PPAR-γ, sarcoidosis development, and inflammatory state could be essential to identify the appropriate therapeutic targets. The synthesis of PPAR-γ agonists or PPAR-γ ligands may be an effective step toward the treatment of sarcoidosis patients in the future.

Impact of Circulating N-Acylethanolamine Levels with Clinical and Laboratory End Points in Hemodialysis Patients

BACKGROUND

Patients with ESRD on maintenance hemodialysis (MHD) are particularly susceptible to dysregulation of energy metabolism, which may manifest as protein energy wasting and cachexia. In recent years, the endocannabinoid system has been shown to play an important role in energy metabolism with potential relevance in ESRD. N-acylethanolamines are a class of fatty acid amides which include the major endocannabinoid ligand, anandamide, and the endogenous peroxisome proliferator-activated receptor-α agonists, oleoylethanolamide (OEA) and palmitoylethanolamide (PEA).

METHODS

Serum concentrations of OEA and PEA were measured in MHD patients and their correlations with various clinical/laboratory indices were examined. Secondarily, we evaluated the association of circulating PEA and OEA levels with 12-month all-cause mortality.

RESULTS

Both serum OEA and PEA levels positively correlated with high-density lipoprotein-cholesterol levels and negatively correlated with body fat and body anthropometric measures. Serum OEA levels correlated positively with serum interleukin-6 (IL-6) (rho = 0.19; p = 0.004). Serum PEA and IL-6 showed a similar but nonsignificant trend (rho = 0.12; p = 0.07). Restricted cubic spline analyses showed that increasing serum OEA and PEA both trended toward higher mortality risk, and these associations were statistically significant for PEA (PEA ≥4.7 pmol/mL; reference: PEA <4.7 pmol/mL) after adjustments in a Cox model (hazard ratio 2.99; 95% confidence interval 1.04, 8.64).

CONCLUSIONS

In MHD patients, OEA and PEA are significantly correlated with variables related to lipid metabolism and body mass. Additionally, higher serum levels of PEA are associated with mortality risk. Future studies are needed to examine the potential mechanisms responsible for these findings and their clinical implications.

Fenofibrate Ameliorates Hepatic Ischemia/Reperfusion Injury in Mice: Involvements of Apoptosis, Autophagy, and PPAR-α Activation

Hepatic ischemia and reperfusion injury is characterized by hepatocyte apoptosis, impaired autophagy, and oxidative stress. Fenofibrate, a commonly used antilipidemic drug, has been verified to exert hepatic protective effects in other cells and animal models. The purpose of this study was to identify the function of fenofibrate on mouse hepatic IR injury and discuss the possible mechanisms. A segmental (70%) hepatic warm ischemia model was established in Balb/c mice. Serum and liver tissue samples were collected for detecting pathological changes at 2, 8, and 24 h after reperfusion, while fenofibrate (50 mg/kg, 100 mg/kg) was injected intraperitoneally 1 hour prior to surgery. Compared to the IR group, pretreatment of FF could reduce the inflammatory response and inhibit apoptosis and autophagy. Furthermore, fenofibrate can activate PPAR-α, which is associated with the phosphorylation of AMPK.

Apigenin Alleviates Liver Fibrosis by Inhibiting Hepatic Stellate Cell Activation and Autophagy via TGF-β1/Smad3 and p38/PPARα Pathways

Objective

The aim of this study is to confirm the hepatocellular protective functions of apigenin and the molecular mechanism on liver fibrosis in mice.

Methods

Carbon tetrachloride (CCl₄) and bile duct ligature (BDL) mouse fibrosis models were used to investigate the effects of apigenin on liver fibrosis. Sixty-six male C57 mice were randomly divided into eight groups, including the vehicle group, CCl₄ group, CCl₄+L-apigenin (20 mg/kg) group, CCl₄+H-apigenin (40 mg/kg) group, sham group, BDL group, BDL+L-apigenin(20 mg/kg) group, and BDL+H-apigenin(40 mg/kg) group. Serum liver enzymes (ALT and AST), proteins associated with autophagy, and indicators linked with the TGF-β1/Smad3 and p38/PPARα pathways were detected using qRT-PCR, immunohistochemical staining, and western blotting.

Results

Our findings confirmed that apigenin could decrease the levels of ALT and AST, suppress the generation of ECM, inhibit the activation of HSCs, regulate the balance of MMP2 and TIMP1, reduce the expression of autophagy-linked protein, and restrain the TGF-β1/Smad3 and p38/PPARα pathways.

Conclusion

Apigenin could alleviate liver fibrosis by inhibiting hepatic stellate cell activation and autophagy via TGF-β1/Smad3 and p38/PPARα pathways.

Bergenin Attenuates Hepatic Fibrosis by Regulating Autophagy Mediated by the PPAR-γ/TGF-β Pathway

Liver fibrosis is a pathological process involving diffuse extracellular matrix (ECM) deposition in the liver. It is typical of many chronic liver diseases, including cirrhosis, and effective drugs are needed. In this study, we explored the protective effect of bergenin on liver fibrosis induced by carbon tetrachloride and bile duct ligation. A variety of molecular biological methods (qRT-PCR, western blotting, and immunohistochemistry) were employed to confirm the increased degree of hepatocyte injury and ECM formation in the disease model, consistent with autophagy and activation of the TGF-β pathway. Bergenin activated PPAR-γ and inhibited TGF-β and autophagy and decreased liver fibrosis by inhibiting hepatocyte necrosis and ECM formation in a dose-dependent manner. The results suggest that bergenin may be a promising drug candidate for the treatment of liver fibrosis.

Role of PPARs in Progression of Anxiety: Literature Analysis and Signaling Pathways Reconstruction

Peroxisome proliferator-activated receptor (PPAR) group includes three isoforms encoded by PPARG, PPARA, and PPARD genes. High concentrations of PPARs are found in parts of the brain linked to anxiety development, including hippocampus and amygdala. Among three PPAR isoforms, PPARG demonstrates the highest expression in CNS, where it can be found in neurons, astrocytes, and glial cells. Herein, the highest PPARG expression occurs in amygdala. However, little is known considering possible connections between PPARs and anxiety behavior. We reviewed possible connections between PPARs and anxiety. We used the Pathway Studio software (Elsevier). Signal pathways were created according to previously developed algorithms. SNEA was performed in Pathway Studio. Current study revealed 14 PPAR-regulated proteins linked to anxiety. Possible mechanism of PPAR involvement in neuroinflammation protection is proposed. Signal pathway reconstruction and reviewing aimed to reveal possible connection between PPARG and CCK-ergic system was conducted. Said analysis revealed that PPARG-dependent regulation of MME and ACE peptidase expression may affect levels of nonhydrolysed, i.e., active CCK-4. Impairments in PPARG regulation and following MME and ACE peptidase expression impairments in amygdala may be the possible mechanism leading to pathological anxiety development, with brain CCK-4 accumulation being a key link. Literature data analysis and signal pathway reconstruction and reviewing revealed two possible mechanisms of peroxisome proliferator-activated receptors involvement in pathological anxiety: (1) cytokine expression and neuroinflammation mechanism and (2) regulation of peptidases targeted to anxiety-associated neuropeptides, primarily CCK-4, mechanism.

Tackling Chronic Inflammation with Withanolide Phytochemicals-A Withaferin a Perspective

Chronic inflammatory diseases are considered to be one of the biggest threats to human health. Most prescribed pharmaceutical drugs aiming to treat these diseases are characterized by side-effects and negatively affect therapy adherence. Finding alternative treatment strategies to tackle chronic inflammation has therefore been gaining interest over the last few decades. In this context, Withaferin A (WA), a natural bioactive compound isolated from Withania somnifera, has been identified as a promising anti-cancer and anti-inflammatory compound. Although the majority of studies focus on the molecular mechanisms of WA in cancer models, recent evidence demonstrates that WA also holds promise as a new phytotherapeutic agent against chronic inflammatory diseases. By targeting crucial inflammatory pathways, including nuclear factor kappa B (NF-κB) and nuclear factor erythroid 2 related factor 2 (Nrf2) signaling, WA suppresses the inflammatory disease state in several in vitro and preclinical in vivo models of diabetes, obesity, neurodegenerative disorders, cystic fibrosis and osteoarthritis. This review provides a concise overview of the molecular mechanisms by which WA orchestrates its anti-inflammatory effects to restore immune homeostasis.

Lipid-Induced Mechanisms of Metabolic Syndrome

Metabolic syndrome (MetS) has a worldwide tendency to increase and depends on many components, which explains the complexity of diagnosis, approaches to the prevention, and treatment of this pathology. Insulin resistance (IR) is the crucial cause of the MetS pathogenesis, which develops against the background of abdominal obesity. In light of recent evidence, it has been shown that lipids, especially fatty acids (FAs), are important signaling molecules that regulate the signaling pathways of insulin and inflammatory mediators. On the one hand, the lack of n-3 polyunsaturated fatty acids (PUFAs) in the body leads to impaired molecular mechanisms of glucose transport, the formation of unresolved inflammation. On the other hand, excessive formation of free fatty acids (FFAs) underlies the development of oxidative stress and mitochondrial dysfunction in MetS. Understanding the molecular mechanisms of the participation of FAs and their metabolites in the pathogenesis of MetS will contribute to the development of new diagnostic methods and targeted therapy for this disease. The purpose of this review is to highlight recent advances in the study of the effect of fatty acids as modulators of insulin response and inflammatory process in the pathogenesis and treatment for MetS.