PPAR-gamma agonists inhibit production of monocyte inflammatory cytokines

Peroxisome Proliferator-Activated Receptors and Caloric Restriction-Common Pathways Affecting Metabolism, Health, and Longevity

Caloric restriction (CR) is a traditional but scientifically verified approach to promoting health and increasing lifespan. CR exerts its effects through multiple molecular pathways that trigger major metabolic adaptations. It influences key nutrient and energy-sensing pathways including mammalian target of rapamycin, Sirtuin 1, AMP-activated protein kinase, and insulin signaling, ultimately resulting in reductions in basic metabolic rate, inflammation, and oxidative stress, as well as increased autophagy and mitochondrial efficiency. CR shares multiple overlapping pathways with peroxisome proliferator-activated receptors (PPARs), particularly in energy metabolism and inflammation. Consequently, several lines of evidence suggest that PPARs might be indispensable for beneficial outcomes related to CR. In this review, we present the available evidence for the interconnection between CR and PPARs, highlighting their shared pathways and analyzing their interaction. We also discuss the possible contributions of PPARs to the effects of CR on whole organism outcomes.

Classical monocyte transcriptomes reveal significant anti-inflammatory statin effect in women with chronic HIV

AIMS

During virally suppressed chronic HIV infection, persistent inflammation contributes to the development of cardiovascular disease (CVD), a major comorbidity in people living with HIV (LWH). Classical blood monocytes (CMs) remain activated during antiretroviral therapy and are a major source of pro-inflammatory and pro-thrombotic factors that contribute to atherosclerotic plaque development and instability.

METHODS AND RESULTS

Here, we identify transcriptomic changes in circulating CMs in peripheral blood mononuclear cell samples from participants of the Women's Interagency HIV Study, selected by HIV and subclinical CVD (sCVD) status. We flow-sorted CM from participants of the Women's Interagency HIV Study and deep-sequenced their mRNA (n = 92). CMs of HIV+ participants showed elevated interleukin (IL)-6, IL-1β, and IL-12β, overlapping with many transcripts identified in sCVD+ participants. In sCVD+ participants LWH, those reporting statin use showed reduced pro-inflammatory gene expression to a level comparable with healthy (HIV-sCVD-) participants. Statin non-users maintained an elevated inflammatory profile and increased cytokine production.

CONCLUSION

Statin therapy has been associated with a lower risk of cardiac events, such as myocardial infarction in the general population, but not in those LWH. Our data suggest that women LWH may benefit from statin therapy even in the absence of overt CVD.

Atheroprotective and atheroregressive potential of azapeptide derivatives of GHRP-6 as selective CD36 ligands in apolipoprotein E-deficient mice

BACKGROUND AND AIMS

Scavenger receptor class B member 3, also known as cluster of differentiation-36 (CD36) receptor, is involved in the uptake and accumulation of modified lipoprotein in macrophages, driving atherosclerosis progression. Azapeptide analogs of growth hormone-releasing peptide-6 (GHRP-6) have been developed as selective CD36 ligands and evaluated for their anti-atherosclerotic properties in apoe^-/- mice.

METHODS

From 4 to 19 weeks of age, male apoe^-/- mice were fed a high fat high cholesterol (HFHC) diet, then switched to normal chow and treated daily with 300 nmol/kg of MPE-001 ([aza-Tyr⁴]-GHRP-6) or MPE-003 ([aza-(N,N-diallylaminobut-2-ynyl)Gly⁴]-GHRP-6) for 9 weeks. In another protocol, mice were fed a HFHC diet throughout the study.

RESULTS

Azapeptides decreased lesion progression in the aortic arch and reduced aortic sinus lesion areas below pre-existing lesions levels in apoe^-/- mice which were switched to chow diet. In mice fed a HFHC throughout the study, azapeptides reduced lesion progression in the aortic vessel and sinus. The anti-atherosclerotic effect of azapeptides was associated with a reduced ratio of iNOS⁺/CD206⁺ macrophages within lesions, and lowered plasma inflammatory cytokine levels. Monocytes from azapeptide-treated mice showed altered mitochondrial oxygen consumption rates, consistent with an M2-like phenotype. These effects were dependent on CD36, and not observed in apoe^-/-cd36^-/- mice.

CONCLUSIONS

Azapeptides MPE-001 and MPE-003 diminished aortic lesion progression and reduced, below pre-existing levels, lesions in the aortic sinus of atherosclerotic mice. A relative increase of M2-like macrophages was observed in lesions, associated with reduced systemic inflammation. Development of CD36-selective azapeptide ligands merits consideration for treating atherosclerotic disease.

Enhancing PPARγ by HDAC inhibition reduces foam cell formation and atherosclerosis in ApoE deficient mice

Atherosclerosis (AS) is a risky cardiovascular disease with limited treatment options. Various pan or type-selective histone deacetylase (HDAC) inhibitors are reportedly atheroprotective against atherosclerosis (AS); however, the key effectors and the main cellular processes that mediate the protective effects remain poorly defined. Here, we report that PPARγ (Peroxisome proliferator-activated receptor gamma), a transcription factor actively involved in lipid metabolism with strong tissue protective and anti-inflammation properties, is a critical mediator of the anti-AS effects by HDAC inhibition. We showed that a well-known pan-HDAC inhibitor TSA (Trichostatin A) reduced foam cell formation of macrophages that is accompanied by a marked elevation of PPARγ and its downstream cholesterol efflux transporter ABCA1 (ATP-binding membrane cassette transport protein A1) and ABCG1. In an AS model of ApoE^-/- mice fed on high-fat diet, TSA treatment alleviated AS lesions, similarly increased PPARγ and the downstream cholesterol transporters and mitigated the induction of inflammatory cytokine TNFα and IL-1β. Exploring the potential cause of PPARγ elevation revealed that TSA induced the acetylation of C/EBPα (CCAAT enhancer binding protein alpha), the upstream regulator of PPARγ, through which it increased PPARγ transactivation. More importantly, we generated a strain of PPARγ/ApoE double knockout mice and demonstrated that lack of PPARγ abrogated the protective effects of TSA on foam cell formation of peritoneal macrophages and the AS pathogenesis. Taken together, these results unravel that C/EBPα and PPARγ are the HDAC-sensitive components of an epigenetic signaling pathway mediating foam cell formation and AS development, and suggest that targeting C/EBPα/PPARγ axis by HDAC inhibitors possesses therapeutic potentials in retarding the progression of AS and the related cardiovascular diseases.

Protocol for Clozapine Rechallenge in a Case of Clozapine-Induced Myocarditis

OBJECTIVE

Protocol for clozapine rechallenge in patients with a history of clozapine-induced myocarditis.

METHOD

Clozapine-related cardiovascular adverse effects including myocarditis and cardiomyopathy have limited its widespread use in treatment-resistant schizophrenia. Here, we present a case of clozapine-induced myocarditis and successful cautious rechallenge. Ms. AA, a young female patient with severe psychosis developed myocarditis during her initial clozapine titration phase, which was thus discontinued. Subsequent response to other medications was poor, and she remained significantly disabled. We reviewed blood-based biomarkers identified during the emergence of her index episode of myocarditis and developed a successful clozapine rechallenge protocol, based on careful monitoring of changes in these indices and a very slow clozapine re-titration.

RESULTS AND CONCLUSIONS

This protocol may have utility in the management of patients with a history of clozapine-induced myocarditis.

Endothelial Dysfunction in Diabetes

Diabetes is a worldwide health issue closely associated with cardiovascular events. Given the pandemic of obesity, the identification of the basic underpinnings of vascular disease is strongly needed. Emerging evidence has suggested that endothelial dysfunction is a critical step in the progression of atherosclerosis. However, how diabetes affects the endothelium is poorly understood. Experimental and clinical studies have illuminated the tight link between insulin resistance and endothelial dysfunction. In addition, macrophage polarization from M2 towards M1 contributes to the process of endothelial damage. The possibility that novel classes of anti-hyperglycemic agents exert beneficial effects on the endothelial function and macrophage polarization has been raised. In this review, we discuss the current status of knowledge regarding the pathological significance of insulin signaling in endothelium. Finally, we summarize recent therapeutic strategies against endothelial dysfunction with an emphasis on macrophage polarity.

Regulation of inflammation in diabetes: From genetics to epigenomics evidence

Background

Diabetes is one of the greatest public health challenges worldwide, and we still lack complementary approaches to significantly enhance the efficacy of preventive and therapeutic approaches. Genetic and environmental factors are the culprits involved in diabetes risk. Evidence from the last decade has highlighted that deregulation in the immune and inflammatory responses increase susceptibility to type 1 and type 2 diabetes. Spatiotemporal patterns of gene expression involved in immune cell polarisation depend on genomic enhancer elements in response to inflammatory and metabolic cues. Several studies have reported that most regulatory genetic variants are located in the non-protein coding regions of the genome and particularly in enhancer regions. The progress of high-throughput technologies has permitted the characterisation of enhancer chromatin properties. These advances support the concept that genetic alteration of enhancers may influence the immune and inflammatory responses in relation to diabetes.

Scope of review

Results from genome-wide association studies (GWAS) combined with functional and integrative analyses have elucidated the impacts of some diabetes risk-associated variants that are involved in the regulation of the immune system. Additionally, genetic variant mapping to enhancer regions may alter enhancer status, which in turn leads to aberrant expression of inflammatory genes associated with diabetes susceptibility. The focus of this review was to provide an overview of the current indications that inflammatory processes are regulated at the genetic and epigenomic levels in diabetes, along with perspectives on future research avenues that may improve understanding of the disease.

Major conclusions

In this review, we provide genetic evidence in support of a deregulated immune response as a risk factor in diabetes. We also argue about the importance of enhancer regions in the regulation of immune cell polarisation and how the recent advances using genome-wide methods for enhancer identification have enabled the determination of the impact of enhancer genetic variation on diabetes onset and phenotype. This could eventually lead to better management plans and improved treatment responses in human diabetes.

Resveratrol attenuates the pathogenic and inflammatory properties of Porphyromonas gingivalis

Porphyromonas gingivalis has been strongly associated with chronic periodontitis, which affects tooth-supporting tissues. This Gram-negative anaerobic bacterium produces a repertoire of virulence factors that modulate tissue destruction directly or indirectly by the induction of inflammatory processes. The aim of this study was to investigate the effects of resveratrol, a major polyphenol found in grapes and wine, on the growth and virulence properties of P. gingivalis as well as on gingival keratinocyte tight junction integrity and the host inflammatory response. Resveratrol exhibited antibacterial activity that may result from damage to the bacterial cell membrane. Resveratrol also killed a pre-formed P. gingivalis biofilm and reduced bacterial adherence to matrix proteins. In addition, resveratrol had a protective effect on the integrity of the keratinocyte tight junctions by inhibiting its breakdown by P. gingivalis. This may be related to the ability of resveratrol to inhibit the protease activities of P. gingivalis. Lastly, resveratrol reduced P. gingivalis-mediated activation of the NF-κB signaling pathway and attenuated TREM-1 gene expression as well as soluble TREM-1 secretion in monocytes. The effect on NF-κB activation likely results from the ability of resveratrol to act as a PPAR-γ agonist. In summary, the antibacterial, anti-adherence, and antiprotease properties of resveratrol, as well as its ability to protect the gingival keratinocyte barrier and attenuate the inflammatory response in monocytes suggest that it may be a promising novel therapeutic agent for treating periodontal disease.

Beneficial Effects of Isoflavones in the Kidney of Obese Rats Are Mediated by PPAR-Gamma Expression

Several studies have demonstrated an important association between altered lipid metabolism and the development of kidney injury because of a high-fat diet. Fructose is also closely associated with renal injury. We opted for a combination of fructose and saturated fats in a diet (DH) that is a model known to induce renal damage in order to evaluate whether soy isoflavones could have promising use in the treatment of renal alterations. After two months of ingestion, there was an expansion of visceral fat, which was associated with long-term metabolic disorders, such as sustained hyperglycemia, insulin resistance, polyuria, dyslipidemia, and hypertension. Additionally, we found a decrease in renal blood flow and an increase in renal vascular resistance. Biochemical markers of chronic kidney disease were detected; there was an infiltration of inflammatory cells with an elevated expression of proinflammatory cytokines (tumor necrosis factor-α, interleukin (IL)-6, and IL-1β), the activation of the renin–angiotensin system, and oxidative/nitrosative stress. Notably, in rats exposed to the DH diet for 120 days, the concomitant treatment with isoflavones after 60 days was able to revert metabolic parameters, renal alterations, and oxidative/nitrosative stress. The beneficial effects of isoflavones in the kidney of the obese rats were found to be mediated by expression of peroxisome proliferator-activated receptor gamma (PPAR-γ).

Losartan improves visceral sensation and gut barrier in a rat model of irritable bowel syndrome

BACKGROUND

Lipopolysaccharide (LPS) or repeated water avoidance stress (WAS) induces visceral allodynia and colonic hyperpermeability via corticotropin-releasing factor (CRF) and proinflammatory cytokines, which is considered to be a rat irritable bowel syndrome (IBS) model. As losartan is known to inhibit proinflammatory cytokine release, we hypothesized that it improves these visceral changes.

METHODS

The threshold of visceromotor response (VMR), that is, abdominal muscle contractions induced by colonic balloon distention was electrophysiologically measured in rats. Colonic permeability was determined in vivo by quantifying the absorbed Evans blue in colonic tissue for 15 minutes spectrophotometrically.

KEY RESULTS

Lipopolysaccharide (1 mg kg^-1 ) subcutaneously (s.c.) reduced the threshold of VMR and increased colonic permeability. Losartan (5-25 mg kg^-1  s.c.) for 3 days inhibited these changes in a dose-dependent manner. Moreover, repeated WAS (1 hour daily for 3 days) or intraperitoneal injection of CRF (50 µg kg^-1 ) induced the similar visceral changes as LPS, which were also eliminated by losartan. These effects by losartan in LPS model were reversed by GW9662 (a peroxisome proliferator-activated receptor-γ [PPAR-γ] antagonist), N^G -nitro-L-arginine methyl ester (a nitric oxide [NO] synthesis inhibitor), or naloxone (an opioid receptor antagonist). Moreover, it also inhibited by sulpiride (a dopamine D₂ receptor antagonist) or domperidone (a peripheral dopamine D₂ antagonist).

CONCLUSION & INFERENCES

Losartan prevented visceral allodynia and colonic hyperpermeability in rat IBS models. These actions may be PPAR-γ-dependent and also mediated by the NO, opioid, and dopamine D₂ pathways. Losartan may be useful for IBS treatment.

Peroxisome Proliferator-Activated Receptors: Experimental Targeting for the Treatment of Inflammatory Bowel Diseases

The peroxisome proliferator-activated receptors (PPARs) are a group of nuclear receptor proteins that promote ligand-dependent transcription of target genes that regulate energy production, lipid metabolism, and inflammation. The PPAR superfamily comprises three subtypes, PPARα, PPARγ, and PPARβ/δ, with differential tissue distributions. In addition to their different roles in the regulation of energy balance and carbohydrate and lipid metabolism, an emerging function of PPARs includes normal homeostasis of intestinal tissue. PPARα activation represses NF-κB signaling, which decreases the inflammatory cytokine production by different cell types, while PPARγ ligands can inhibit activation of macrophages and the production of inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, and Il-1β. In this regard, the anti-inflammatory responses induced by PPAR activation might restore physiopathological imbalances associated with inflammatory bowel diseases (IBD). Thus, PPARs and their ligands have important therapeutic potential. This review briefly discusses the roles of PPARs in the physiopathology and therapies of the most important IBDs, ulcerative colitis (UC), and Crohn's disease (CD), as well some new experimental compounds with PPAR activity as promising drugs for IBD treatment.

Airway Remodeling in Asthma

Asthma is an inflammatory disease of the airways that may result from exposure to allergens or other environmental irritants, resulting in bronchoconstriction, wheezing, and shortness of breath. The structural changes of the airways associated with asthma, broadly referred to as airway remodeling, is a pathological feature of chronic asthma that contributes to the clinical manifestations of the disease. Airway remodeling in asthma constitutes cellular and extracellular matrix changes in the large and small airways, epithelial cell apoptosis, airway smooth muscle cell proliferation, and fibroblast activation. These pathological changes in the airway are orchestrated by crosstalk of different cell types within the airway wall and submucosa. Environmental exposures to dust, chemicals, and cigarette smoke can initiate the cascade of pro-inflammatory responses that trigger airway remodeling through paracrine signaling and mechanostimulatory cues that drive airway remodeling. In this review, we explore three integrated and dynamic processes in airway remodeling: (1) initiation by epithelial cells; (2) amplification by immune cells; and (3) mesenchymal effector functions. Furthermore, we explore the role of inflammaging in the dysregulated and persistent inflammatory response that perpetuates airway remodeling in elderly asthmatics.

Regulation of Tumor Immunity by Lysophosphatidic Acid

The tumor microenvironment (TME) may be best conceptualized as an ecosystem comprised of cancer cells interacting with a multitude of stromal components such as the extracellular matrix (ECM), blood and lymphatic networks, fibroblasts, adipocytes, and cells of the immune system. At the center of this crosstalk between cancer cells and their TME is the bioactive lipid lysophosphatidic acid (LPA). High levels of LPA and the enzyme generating it, termed autotaxin (ATX), are present in many cancers. It is also well documented that LPA drives tumor progression by promoting angiogenesis, proliferation, survival, invasion and metastasis. One of the hallmarks of cancer is the ability to modulate and escape immune detection and eradication. Despite the profound role of LPA in regulating immune functions and inflammation, its role in the context of tumor immunity has not received much attention until recently where emerging studies highlight that this signaling axis may be a means that cancer cells adopt to evade immune detection and eradication. The present review aims to look at the immunomodulatory actions of LPA in baseline immunity to provide a broad understanding of the subject with a special emphasis on LPA and cancer immunity, highlighting the latest progress in this area of research.

Liver-related long-term outcomes of thiazolidinedione use in persons with type 2 diabetes

BACKGROUND & AIMS

Studies have described prominent histologic improvement in patients with nonalcoholic steatohepatitis (NASH) using thiazolidinedione (TZD); however, these were all short term with moderate sample size, no liver-related long-term outcomes could be noted.

METHODS

This retrospective cohort study enrolled patients with newly diagnosed type 2 diabetes mellitus (T2DM) from Taiwan's National Health Insurance Research Database between 1 January 2000 and 31 December 2013. We matched TZD users and nonusers at a 1:1 ratio through propensity score matching. This study included 5095 paired TZD users and nonusers. Cox proportional hazard models were used to compare the risks of cirrhosis, hepatic decompensation, hepatic failure and all-cause mortality between TZD users and nonusers. The Kaplan-Meier method was used to compare the cumulative incidence of these main outcomes.

RESULTS

The incidence rates of cirrhosis, hepatic decompensation, hepatic failure and all-cause mortality during follow-up were 0.77 vs 1.95, 1.43 vs 1.75, 0.36 vs 0.70, and 4.89 vs 3.78 per 1000 person-years between TZD users and nonusers. The adjusted hazard ratios of cirrhosis, hepatic decompensation, hepatic failure and all-cause mortality were 0.39 (95% confidence interval [CI]: 0.21-0.72), 0.86 (95% CI: 0.52-1.44), 0.46 (95% CI: 0.18-1.17) and 1.18 (95% CI: 0.87-1.61) respectively.

CONCLUSIONS

Our study demonstrated that TZD use could significantly lower the risk of cirrhosis. In clinical settings, TZD use might be able to improve liver-related long-term outcomes.

Cell-intrinsic metabolic regulation of mononuclear phagocyte activation: Findings from the tip of the iceberg

We have only recently started to appreciate the extent to which immune cell activation involves significant changes in cellular metabolism. We are now beginning to understand how commitment to specific metabolic pathways influences aspects of cellular biology that are the more usual focus of immunological studies, such as activation-induced changes in gene transcription, post-transcriptional regulation of transcription, post-translational modifications of proteins, cytokine secretion, etc. Here, we focus on metabolic reprogramming in mononuclear phagocytes downstream of stimulation with inflammatory signals (such as LPS and IFNγ) vs alternative activation signals (IL-4), with an emphasis on work on dendritic cells and macrophages from our laboratory, and related studies from others. We cover aspects of glycolysis and its branching pathways (glycogen synthesis, pentose phosphate, serine synthesis, hexose synthesis, and glycerol 3 phosphate shuttle), the tricarboxylic acid pathway, fatty acid synthesis and oxidation, and mitochondrial biology. Although our understanding of the metabolism of mononuclear phagocytes has progressed significantly over the last 10 years, major challenges remain, including understanding the effects of tissue residence on metabolic programming related to cellular activation, and the translatability of findings from mouse to human biology.

Mechanisms of action, chemical characteristics, and model systems of obesogens

There is increasing evidence for the role of environmental endocrine disrupting contaminants, coined obesogens, in exacerbating the rising obesity epidemic. Obesogens can be found in everyday items ranging from pesticides to food packaging. Although research shows that obesogens can have effects on adipocyte size, phenotype, metabolic activity, and hormone levels, much remains unknown about these chemicals. This review will discuss what is currently known about the mechanisms of obesogens, including expression of the PPARs, hormone interference, and inflammation. Strategies for identifying obesogenic chemicals and their mechanisms through chemical characteristics and model systems will also be discussed. Ultimately, research should focus on improving models to discern precise mechanisms of obesogenic action and to test therapeutics targeting these mechanisms.

The age-related microglial transformation in Alzheimer's disease pathogenesis

Neuroinflammatory responses mediated by microglia, the resident immune cells of the central nervous system, have long been a subject of study in the field of Alzheimer's disease (AD). Microglia express a wide range of receptors that act as molecular sensors, through which they can fulfill their various functions. In this review, we first analyzed the changes in the expression levels of microglial membrane receptors SR-A, TREM2, CD36, CD33, and CR3 in aging and AD and described the different roles of these receptors in amyloid-beta clearance and inflammatory responses. Two classical hallmarks of AD are extracellular amyloid-beta deposits and intracellular aggregated phosphorylated tau. In AD, microglia reaction was initially thought to be triggered by amyloid deposits. New evidence showed it also associated with increased phosphorylation of tau. However, which first appeared and induced activated microglia is not clear. Then we summarized diverse opinions on it. Besides, as AD is tightly linked to aging, and microglia changes dramatically on aging, yet the relative impacts of both aging and microglia are less frequently considered, so at last, we discussed the roles of aging microglia in AD. We hope to provide a reference for subsequent research.

Pioglitazone-Mediated Peroxisome Proliferator-Activated Receptor γ Activation Aggravates Murine Immune-Mediated Hepatitis

The nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) regulates target gene expression upon ligand binding. Apart from its effects on metabolism, PPARγ activity can inhibit the production of pro-inflammatory cytokines by several immune cells, including dendritic cells and macrophages. In chronic inflammatory disease models, PPARγ activation delays the onset and ameliorates disease severity. Here, we investigated the effect of PPARγ activation by the agonist Pioglitazone on the function of hepatic immune cells and its effect in a murine model of immune-mediated hepatitis. Cytokine production by both liver sinusoidal endothelial cells (IL-6) and in T cells ex vivo (IFNγ) was decreased in cells from Pioglitazone-treated mice. However, PPARγ activation did not decrease pro-inflammatory tumor necrosis factor alpha TNFα production by Kupffer cells after Toll-like receptor (TLR) stimulation ex vivo. Most interestingly, although PPARγ activation was shown to ameliorate chronic inflammatory diseases, it did not improve hepatic injury in a model of immune-mediated hepatitis. In contrast, Pioglitazone-induced PPARγ activation exacerbated D-galactosamine (GalN)/lipopolysaccharide (LPS) hepatitis associated with an increased production of TNFα by Kupffer cells and increased sensitivity of hepatocytes towards TNFα after in vivo Pioglitazone administration. These results unravel liver-specific effects of Pioglitazone that fail to attenuate liver inflammation but rather exacerbate liver injury in an experimental hepatitis model.

Anthocyanins reduce inflammation and improve glucose and lipid metabolism associated with inhibiting nuclear factor-kappaB activation and increasing PPAR-γ gene expression in metabolic syndrome subjects

Anthocyanins exhibit antioxidant and anti-inflammatory activities via a multitude of biochemical mechanisms. However, the signaling pathways involved in the actions of anthocyanins against chronic inflammation are not fully understood. The effects of berry-rich anthocyanin supplements (320 mg/day) for four weeks were examined on features of metabolic syndrome components and the expression of PPAR-γ, Nrf2, and NF-κB dependent genes in MetS and healthy subjects. Total RNA was isolated from whole blood with the PAXgene proprietary blood collection system. Four weeks anthocyanin consumption significantly decreased fasting blood glucose (15.7% vs 3.2%), TG (18.2% vs -1.39%), cholesterol (33.5% vs 1.56%) and LDL (28.4% vs -15.6%) in the MetS compared to Control group (P-value < 0.05, 95% CI). There was a significant up regulation in the expression PPAR-γ gene associated with the lipid and glucose metabolism in MetS subjects which negatively correlated (P-value < 0.01) with the change in the FBG (r = -0.488), Cholesterol (r = -0.496), TG (r = -0.513) and LDL (r = -0.519). Moreover, anthocyanin supplementation decreases serum hs-CRP (-36.3% vs 6.25%) in MetS in compared to Control group (P-value < 0.05). Anthocyanin supplementation also down-regulated the expression of NF-κB dependent genes including TNF-α (-28% and -15%), IL-6 (-16.1% and -13.6%), IL-1A (-21.5% and -12.9%), PCAM-1 (-15% and -17.5%), and COX-2(-26% and -27%) in both MetS and Control group respectively (P-value < 0.05). The study results suggested that berry supplements improved selected features of metabolic syndrome and related cardiovascular risk factors. These benefits may be due to the inhibition of NF-κB dependent gene expression and enhancement of PPAR-γ.

Probabilistic human health risk assessment of perfluorooctane sulfonate (PFOS) by integrating in vitro, in vivo toxicity, and human epidemiological studies using a Bayesian-based dose-response assessment coupled with physiologically based pharmacokinetic (PBPK) modeling approach

BACKGROUND

Environmental exposure to perfluorooctane sulfonate (PFOS) is associated with various adverse outcomes in humans. However, risk assessment for PFOS with the traditional risk estimation method is faced with multiple challenges because there are high variabilities and uncertainties in its toxicokinetics and toxicity between species and among different types of studies.

OBJECTIVES

This study aimed to develop a robust probabilistic risk assessment framework accounting for interspecies and inter-experiment variabilities and uncertainties to derive the human equivalent dose (HED) and reference dose for PFOS.

METHODS

A Bayesian dose-response model was developed to analyze selected 34 critical studies, including human epidemiological, animal in vivo, and ToxCast in vitro toxicity datasets. The dose-response results were incorporated into a multi-species physiologically based pharmacokinetic (PBPK) model to reduce the toxicokinetic/toxicodynamic variabilities. In addition, a population-based probabilistic risk assessment of PFOS was performed for Asian, Australian, European, and North American populations, respectively, based on reported environmental exposure levels.

RESULTS

The 5th percentile of HEDs derived from selected studies was estimated to be 21.5 (95% CI: 10.6-36.3) ng/kg/day. After exposure to environmental levels of PFOS, around 50% of the population in all studied populations would likely have >20% of increase in serum cholesterol, but the effects on other endpoints were estimated to be minimal (<10% changes). There was a small population (~10% of the population) that was highly sensitive to endocrine disruption and cellular response by environmental PFOS exposure.

CONCLUSION

Our results provide insights into a complete risk characterization of PFOS and may help regulatory agencies in the reevaluation of PFOS risk. Our new probabilistic approach can conduct dose-response analysis of different types of toxicity studies simultaneously and this method could be used to improve risk assessment for other perfluoroalkyl substances (PFAS).

Rosiglitazone augments antioxidant response in the human trophoblast and prevents apoptosis†

Insufficient perfusion of the trophoblast by maternal blood is associated with an increased generation of reactive oxygen species and complications of the placenta. In this study, we first examined whether rosiglitazone, an agonist of the peroxisome proliferator-activated receptor-γ (PPARγ), protects the human trophoblast from oxidative injury by regulating key antioxidant proteins, catalase (CAT) and the superoxide dismutases (SOD1 and SOD2). In first trimester placental explants, localization of CAT was limited to cytotrophoblasts, whereas SOD1 was expressed in both the cyto- and syncytiotrophoblasts. In first trimester placental explants, hypoxia decreased the expression of both SOD1 and SOD2, and increased apoptosis. Treatment with rosiglitazone dose-dependently upregulated anti-oxidative CAT and SOD2, and rescued hypoxic injury in first trimester villous explants and JEG-3 cells, strongly suggesting the involvement of the PPARγ in regulating their expressions. Rosiglitazone facilitated transcription activity of PPARγ, and enhanced promotor binding, increased transcriptional activity at the CAT promoter, and elevated protein expression/activity. Treatment of hypoxic JEG-3 cells with rosiglitazone resulted in mitochondrial membrane potential increase and a reduction of caspase 9 and caspase 3 activity which is consistent with improved cell survival. To complement PPARγ activation data, we also utilized the antagonist (SR-202) and siRNA to suppress PPARγ expression and demonstrate the specific role of PPARγ in reducing ROS and oxidative stress. Ex vivo examination of term human placenta revealed lower expression of antioxidant proteins in pathologic compared to healthy placental tissues, which could be rescued by rosiglitazone, indicating that rosiglitazone can improve survival of the trophoblast under pathological conditions. These findings provide evidence that the PPARγ pathway directly influences cellular antioxidants production and the pathophysiology of placental oxidative stress.

PPARγ inhibition boosts efficacy of PD-L1 Checkpoint Blockade Immunotherapy against Murine Melanoma in a sexually dimorphic manner

Immune checkpoint blockade-based immunotherapy has become standard of care for multiple cancer types. However, the overall response rates among various cancer types still remain unsatisfactory. There is a pressing clinical need to identify combination therapies to improve efficacy of anticancer immunotherapy. We previously showed that pharmacologic inhibition of PPARγ by GW9662 boosts αPD-L1 and αPD-1 antibody efficacy in treating murine mammary tumors. In addition, we defined sexually dimorphic αPD-L1 efficacy in B16 melanoma. Here, we show a sexually dimorphic response to the combination of GW9662 and αPD-L1 immunotherapy in B16 melanoma. Combination effects were observed in female, but not male hosts. Neither female oöphorectomy impairs, nor does male castration rescue the combination effects, suggesting a sex hormone-independent response to this combination therapy. In diet-induced obese females, melanoma growth remained responsive to the combination treatment, albeit less robustly than lean females. These findings are informative for future design and application of immunotherapy-related combination therapy for treating human melanoma patients by taking gender and obesity status into consideration.

Interaction of epidermal growth factor with COX-2 products and peroxisome proliferator-activated receptor-γ system in experimental rat Barrett's esophagus

Mixed acidic-alkaline refluxate is a major pathogenic factor in chronic esophagitis progressing to Barrett's esophagus (BE). We hypothesized that epidermal growth factor (EGF) can interact with COX-2 and peroxisome proliferator-activated receptor-γ (PPARγ) in rats surgically prepared with esophagogastroduodenal anastomosis (EGDA) with healthy or removed salivary glands to deplete salivary EGF. EGDA rats were treated with 1) vehicle, 2) EGF or PPARγ agonist pioglitazone with or without EGFR kinase inhibitor tyrphostin A46, EGF or PPARγ antagonist GW9662 respectively, 3) ranitidine or pantoprazole, and 4) the selective COX-2 inhibitor celecoxib combined with pioglitazone. At 3 mo, the esophageal damage and the esophageal blood flow (EBF) were determined, the mucosal expression of EGF, EGFR, COX-2, TNFα, and PPARγ mRNA and phospho-EGFR/EGFR protein was analyzed. All EGDA rats developed chronic esophagitis, esophageal ulcerations, and intestinal metaplasia followed by a fall in the EBF, an increase in the plasma of IL-1β, TNFα, and mucosal PGE₂ content, the overexpression of COX-2-, and EGF-EGFR mRNAs, and proteins, and these effects were aggravated by EGF and attenuated by pioglitazone. The rise in EGF and COX-2 mRNA was inhibited by pioglitazone but reversed by pioglitazone cotreated with GW9662. We conclude that 1) EGF can interact with PG/COX-2 and the PPARγ system in the mechanism of chronic esophagitis; 2) the deleterious effect of EGF involves an impairment of EBF and the overexpression of COX-2 and EGFR, and 3) agonists of PPARγ and inhibitors of EGFR may be useful in the treatment of chronic esophagitis progressing to BE.NEW & NOTEWORTHY Rats with EGDA exhibited chronic esophagitis accompanied by a fall in EBF and an increase in mucosal expression of mRNAs for EGF, COX-2, and TNFα, and these effects were exacerbated by exogenous EGF and reduced by removal of a major source of endogenous EGF with salivectomy or concurrent treatment with tyrphostin A46 or pioglitazone combined with EGF. Beneficial effects of salivectomy in an experimental model of BE were counteracted by PPARγ antagonist, whereas selective COX-2 inhibitor celecoxib synergistically with pioglitazone reduced severity of esophageal damage and protected esophageal mucosa from reflux. We propose the cross talk among EGF/EGFR, PG/COX-2, and proinflammatory cytokines with PPARγ pathway in the mechanism of pathogenesis of chronic esophagitis progressing to BE and EAC.

Mechanisms of Macrophage Polarization in Insulin Signaling and Sensitivity

Type-2 diabetes (T2D) is a disease of two etiologies: metabolic and inflammatory. At the cross-section of these etiologies lays the phenomenon of metabolic inflammation. Whilst metabolic inflammation is characterized as systemic, a common starting point is the tissue-resident macrophage, who's successful physiological or aberrant pathological adaptation to its microenvironment determines disease course and severity. This review will highlight the key mechanisms in macrophage polarization, inflammatory and non-inflammatory signaling that dictates the development and progression of insulin resistance and T2D. We first describe the known homeostatic functions of tissue macrophages in insulin secreting and major insulin sensitive tissues. Importantly we highlight the known mechanisms of aberrant macrophage activation in these tissues and the ways in which this leads to impairment of insulin sensitivity/secretion and the development of T2D. We next describe the cellular mechanisms that are known to dictate macrophage polarization. We review recent progress in macrophage bio-energetics, an emerging field of research that places cellular metabolism at the center of immune-effector function. Importantly, following the advent of the metabolically-activated macrophage, we cover the known transcriptional and epigenetic factors that canonically and non-canonically dictate macrophage differentiation and inflammatory polarization. In closing perspectives, we discuss emerging research themes and highlight novel non-inflammatory or non-immune roles that tissue macrophages have in maintaining microenvironmental and systemic homeostasis.

Alpha-linolenic acid protects against lipopolysaccharide-induced acute lung injury through anti-inflammatory and anti-oxidative pathways

Alpha-linolenic acid (ALA), an important component of polyunsaturated fatty acids (PUFAs), possesses potent anti-inflammatory properties. To date, the effects of ALA on acute lung injury (ALI) remains unknown. This study was designed to investigate the potential protective effects of ALA on LPS-induced ALI and the underpinning mechanisms. An animal model of ALI was established via intratracheally injection of lipopolysaccharide (LPS, 1 mg/kg). We found that lung wet/dry weight ratio and protein concentration in Bronchoalveolar lavage fluid (BALF) were dramatically decreased by ALA pretreatment. Treatment with ALA significantly alleviated the infiltration of total cells and neutrophils, while increased the number of the macrophages. ALA significantly inhibited the secretion of proinflammatory cytokines including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) and increased anti-inflammatory cytokine. Moreover, we found that the levels of myeloperoxidase (MPO) and malondialdehyde (MDA) were highly increased in LPS-induced ALI, while the activities of glutathione (GSH) and superoxide dismutase (SOD) were decreased, which were reversed by ALA. ALA attenuated LPS-induced histopathological changes and apoptosis. Furthermore, ALA significantly inhibited the phosphorylation of IκBα and NF-κB (p65) activation in ALI. ALA showed anti-inflammatory effects in mice with LPS-induced ALI. NF-κB pathway may be involved in ALA mediated protective effects.

In vitro prebiotic potential of agricultural by-products on intestinal fermentation, gut barrier and inflammatory status of piglets

The inclusion of fibre-rich ingredients in diets is one possible strategy to enhance intestinal fermentation and positively impact gut ecology, barrier and immunity. Nowadays, inulin-type fructans are used as prebiotics in the feed of piglets to manipulate gut ecology for health purposes. Likewise, some by-products could be considered as sustainable and inexpensive ingredients to reduce gut disorders at weaning. In the present study, chicory root and pulp, citrus pulp, rye bran and soya hulls were tested in a three-step in vitro model of the piglet's gastro-intestinal tract combining a pepsin-pancreatin hydrolysis (digestion), a dialysis step using cellulose membranes (absorption) and a colonic batch fermentation (fermentation). The fermentation kinetics, SCFA and microbiota profiles in the fermentation broth were assessed as indicators of prebiotic activity and compared with the ones of inulin. The immunomodulatory effects of fermentation supernatant (FS) were investigated in cultured intestinal porcine epithelial cells (IPEC-J2) by high-throughput quantitative PCR. Chicory root displayed a rapid and extensive fermentation and induced the second highest butyrate ratio after inulin. Citrus pulp demonstrated high acetate ratios and induced elevated Clostridium clusters IV and XIVa levels. Chicory root and pulp FS promoted the intestinal barrier integrity with up-regulated tight and adherens junction gene expressions in comparison with inulin FS. Chicory pulp FS exerted anti-inflammatory effects in cultured IPEC-J2. The novel approach combining an in vitro fermentation model with IPEC-J2 cells highlighted that both chicory root and pulp appear to be promising ingredients and should be considered to promote intestinal health at weaning.

Longitudinal relationships between rheumatoid factor and cytokine expression by immunostimulated peripheral blood lymphocytes from patients with rheumatoid arthritis: New insights into B-cell activation

To identify associations between immunostimulated cytokine production and disease characteristics, peripheral blood lymphocytes were collected from 155 adult patients with rheumatoid arthritis (RA) before and after a 5-year interval. The lymphocytes were activated in vitro with T-cell stimulants, cytosine-phosphate-guanine (CpG) oligonucleotide, and medium alone (negative control). Expression of 17 cytokines was evaluated with immunoassays, and factor analysis was used to reduce data complexity and identify cytokine combinations indicative of cell types preferentially activated by each immunostimulant. The findings showed that the highest numbers of correlations were between cytokine levels and rheumatoid factor (RF) positivity and between cytokine levels and disease duration. Scores for cytokines driven by CpG and medium alone were negatively associated with RF positivity and disease duration at baseline but positively associated with both at 5 years. Our findings suggest that RF expression sustained over time increases activation of B cells and monocytes without requirements for T-cell functions.

Peroxisome proliferator-activated receptor gamma blunts endothelin-1-mediated contraction of the uterine artery in a murine model of high-altitude pregnancy

The environmental hypoxia of high altitude (HA) increases the incidence of intrauterine growth restriction (IUGR) approximately threefold. The peroxisome proliferator-activated receptor γ (PPAR-γ), a ligand-activated nuclear receptor that promotes vasorelaxation by increasing nitric oxide and downregulating endothelin-1 (ET-1) production, has been implicated in IUGR. Based on our prior work indicating that pharmacologic activation of the PPARγ pathway protects against hypoxia-associated IUGR, we used an experimental murine model to determine whether such effects may be attributed to vasodilatory effects in the uteroplacental circulation. Using wire myography, ex vivo vasoreactivity studies were conducted in uterine arteries (UtA) isolated from pregnant mice exposed to hypoxia or normoxia from gestational day 14.5 to 18.5. Exposure to troglitazone, a high-affinity PPARγ agonist-induced vasorelaxation in UtA preconstricted with phenylephrine, with HA-UtA showing increased sensitivity. Troglitazone blunted ET-1-induced contraction of UtA in hypoxic and normoxic dams equivalently. Immunohistological analysis revealed enhanced staining for ET-1 receptors in the placental labyrinthine zone in hypoxic compared to normoxic dams. Our results suggest that pharmacologic PPAR-γ activation, via its vasoactive properties, may protect the fetal growth under hypoxic conditions by improving uteroplacental perfusion and thereby justify further investigation into PPARγ as a therapeutic target for IUGR in pregnancies complicated by hypoxia.

Omega-3 Versus Omega-6 Polyunsaturated Fatty Acids in the Prevention and Treatment of Inflammatory Skin Diseases

Omega-3 (ω-3) and omega-6 (ω-6) polyunsaturated fatty acids (PUFAs) are nowadays desirable components of oils with special dietary and functional properties. Their therapeutic and health-promoting effects have already been established in various chronic inflammatory and autoimmune diseases through various mechanisms, including modifications in cell membrane lipid composition, gene expression, cellular metabolism, and signal transduction. The application of ω-3 and ω-6 PUFAs in most common skin diseases has been examined in numerous studies, but their results and conclusions were mostly opposing and inconclusive. It seems that combined ω-6, gamma-linolenic acid (GLA), and ω-3 long-chain PUFAs supplementation exhibits the highest potential in diminishing inflammatory processes, which could be beneficial for the management of inflammatory skin diseases, such as atopic dermatitis, psoriasis, and acne. Due to significant population and individually-based genetic variations that impact PUFAs metabolism and associated metabolites, gene expression, and subsequent inflammatory responses, at this point, we could not recommend strict dietary and supplementation strategies for disease prevention and treatment that will be appropriate for all. Well-balanced nutrition and additional anti-inflammatory PUFA-based supplementation should be encouraged in a targeted manner for individuals in need to provide better management of skin diseases but, most importantly, to maintain and improve overall skin health.

Modulating Tumor-Associated Macrophage Polarization by Synthetic and Natural PPARγ Ligands as a Potential Target in Breast Cancer

Activation of peroxisome proliferator-activated receptor gamma (PPARγ) elicits anti-proliferative effects on different tumor cells, including those derived from breast cancer. PPARγ is also expressed in several cells of the breast tumor microenvironment, among which tumor associated macrophages (TAMs) play a pivotal role in tumor progression and metastasis. We explored the ability of synthetic and natural PPARγ ligands to modulate TAM polarization. The ligands included rosiglitazone (BRL-49653), and two docosahexaenoic acid (DHA) conjugates, N-docosahexaenoyl ethanolamine (DHEA) and N-docosahexaenoyl serotonin (DHA-5-HT). Human THP-1 monocytic cells were differentiated into M0, M1 and M2 macrophages that were characterized by qRT-PCR, ELISA and western blotting. A TAM-like phenotypic state was generated by adding two different breast cancer cell conditioned media (BCC-CM) to the cultures. Macrophages exposed to BCC-CM concomitantly exhibited M1 and M2 phenotypes. Interestingly, rosiglitazone, DHEA and DHA-5-HT attenuated cytokine secretion by TAMs, and this effect was reversed by the PPARγ antagonist GW9662. Given the key role played by PPARγ in the crosstalk between cancer cells and TAMs in tumor progression, its activation via endogenous or synthetic ligands may lead to novel strategies that target both epithelial neoplastic cells and the tumor microenvironment.

Role of Toll-like receptor 2 against Streptococcus uberis infection in primary mouse mammary epithelial cells

Mammary epithelial cells (MECs) play an important role against Streptococcus uberis infection which is one of the main causes of bovine mastitis and a potential threat to human health. Toll-like receptors (TLRs) and their mediated signaling pathways are critical in both innate and infection responses, yet their roles in anti-S. uberis infection in MECs remains poorly defined. In this work we investigated the regulatory mechanisms of TLR2 in inflammatory responses, where WT and TLR2^-/- mice were euthanized at 15-18 days gestation, and mammary gland tissues were collected aseptically. The mouse MECs (MMECs) were isolated by combined digestion with type I collagenase, hyaluronidase and trypsin. We challenged MMECs with S. uberis and quantified antioxidant capacity as well as reactive oxygen species (ROS), proinflammatory cytokines and cell damage at different times. The loss of TLR2 function in MMECs results in more serious cell damage, increased cell adhesion, and significantly decreased ROS and mitochondrial ROS (mROS) with bactericidal function in response to S. uberis infection. Moreover, it was observed that the antioxidant capacity declined, and the production of TLR2-mediated cytokines (except CXC ligand 15) also were reduced. We demonstrated that TLR2 can mediate cellular anti-infective processes in MMECs by regulating the production of ROS and mROS and the secretion of cytokines. The results suggest an unpredicted role of TLR2 in MMECs in response to S. uberis infection.

Pyridinecarboxylic Acid Derivative Stimulates Pro-Angiogenic Mediators by PI3K/AKT/mTOR and Inhibits Reactive Nitrogen and Oxygen Species and NF-κB Activation Through a PPARγ-Dependent Pathway in T. cruzi-Infected Macrophages

Chagas disease is caused by Trypanosoma cruzi infection and represents an important public health concern in Latin America. Macrophages are one of the main infiltrating leukocytes in response to infection. Parasite persistence could trigger a sustained activation of these cells, contributing to the damage observed in this pathology, particularly in the heart. HP₂₄, a pyridinecarboxylic acid derivative, is a new PPARγ ligand that exerts anti-inflammatory and pro-angiogenic effects. The aim of this work was to deepen the study of the mechanisms involved in the pro-angiogenic and anti-inflammatory effects of HP₂₄ in T. cruzi-infected macrophages, which have not yet been elucidated. We show for the first time that HP₂₄ increases expression of VEGF-A and eNOS through PI3K/AKT/mTOR and PPARγ pathways and that HP₂₄ inhibits iNOS expression and NO release, a pro-inflammatory mediator, through PPARγ-dependent mechanisms. Furthermore, this study shows that HP₂₄ modulates H₂O₂ production in a PPARγ-dependent manner. It is also demonstrated that this new PPARγ ligand inhibits the NF-κB pathway. HP₂₄ inhibits IKK phosphorylation and IκB-α degradation, as well as p65 translocation to the nucleus in a PPARγ-dependent manner. In Chagas disease, both the sustained increment in pro-inflammatory mediators and microvascular abnormalities are crucial aspects for the generation of cardiac damage. Elucidating the mechanism of action of new PPARγ ligands is highly attractive, given the fact that it can be used as an adjuvant therapy, particularly in the case of Chagas disease in which inflammation and tissue remodeling play an important role in the pathophysiology of this disease.

Stabilizing Peri-Stent Restenosis Using a Novel Therapeutic Carrier

Late in-stent restenosis remains a significant problem. Bare-metal stents were implanted into peripheral arteries in miniature swine, followed by direct intra-arterial infusion of nitric oxide-loaded echogenic liposomes (ELIPs) and anti-intercellular adhesion molecule-1 conjugated ELIPs loaded with pioglitazone exposed to an endovascular catheter with an ultrasonic core. Ultrasound-facilitated delivery of ELIP formulations into stented peripheral arteries attenuated neointimal growth. Local atheroma-targeted, ultrasound-triggered delivery of nitric oxide and pioglitazone, an anti-inflammatory peroxisome proliferator-activated receptor-γ agonist, into stented arteries has the potential to stabilize stent-induced neointimal growth and obviate the need for long-term antiplatelet therapy.

Anti-NASH Drug Development Hitches a Lift on PPAR Agonism

Non-alcoholic fatty liver disease (NAFLD) affects one-third of the population worldwide, of which a substantial number of patients suffer from non-alcoholic steatohepatitis (NASH). NASH is a severe condition characterized by steatosis and concomitant liver inflammation and fibrosis, for which no drug is yet available. NAFLD is also generally conceived as the hepatic manifestation of the metabolic syndrome. Consequently, well-established drugs that are indicated for the treatment of type 2 diabetes and hyperlipidemia are thought to exert effects that alleviate the pathological features of NASH. One class of these drugs targets peroxisome proliferator-activated receptors (PPARs), which are nuclear receptors that play a regulatory role in lipid metabolism and inflammation. Therefore, PPARs are now also being investigated as potential anti-NASH druggable targets. In this paper, we review the mechanisms of action and physiological functions of PPARs and discuss the position of the different PPAR agonists in the therapeutic landscape of NASH. We particularly focus on the PPAR agonists currently under evaluation in clinical phase II and III trials. Preclinical strategies and how refinement and optimization may improve PPAR-targeted anti-NASH drug testing are also discussed. Finally, potential caveats related to PPAR agonism in anti-NASH therapy are stipulated.

PPAR-γ signalling as a key mediator of human hair follicle physiology and pathology

Peroxisome proliferator-activated receptors (PPARs) are abundantly expressed in human skin, with PPAR-γ being the most intensively investigated isoform. In various ex vivo and in vivo models, PPAR-γ-mediated signalling has recently surfaced as an essential element of hair follicle (HF) development, growth and stem cell biology. Moreover, the availability of novel, topically applicable PPAR-γ modulators with a favourable toxicological profile has extended the range of potential applications in clinical dermatology. In this review, we synthesize where this field currently stands and sketch promising future research avenues, focussing on the role of PPAR-γ-mediated signalling in the biology and pathology of human scalp HFs, with special emphasis on scarring alopecias such as lichen planopilaris and frontal fibrosing alopecia as model human epithelial stem cell diseases. In particular, we discuss whether and how pharmacological modulation of PPAR-γ signalling may be employed for the management of hair growth disorders, for example, in scarring alopecia (by reducing HF inflammation as well as by promoting the survival and suppressing pathological epithelial-mesenchymal transition of keratin 15 + epithelial stem cells in the bulge) and in hirsutism/hypertrichosis (by promoting catagen development). Moreover, we explore the potential role of PPAR-γ in androgenetic alopecia, HF energy metabolism and HF ageing, and consider clinical perspectives that emanate from the limited data available on this so far. As this field of translational human hair research is still in its infancy, many open questions exist, for which we briefly delineate selected experimental approaches that promise to generate instructive answers in the near future.

Clostridium butyricum Modulates the Microbiome to Protect Intestinal Barrier Function in Mice with Antibiotic-Induced Dysbiosis

Clostridium butyricum MIYAIRI 588 (CBM 588) is a probiotic bacterium that has previously been used to prevent antibiotic-associated diarrhea. However, the underlying mechanism by which CBM 588 protects the gut epithelial barrier remains unclear. Here, we show that CBM 588 increased the abundance of Bifidobacterium, Lactobacillus, and Lactococcus species in the gut microbiome and also enhanced the intestinal barrier function of mice with antibiotic-induced dysbiosis. Additionally, CBM 588 significantly promoted the expansion of IL-17A-producing γδT cells and IL-17A-producing CD4 cells in the colonic lamina propria (cLP), which was closely associated with changes in the intestinal microbial composition. Additionally, CBM 588 plays an important role in controlling antibiotic-induced gut inflammation through upregulation of anti-inflammatory lipid metabolites such as palmitoleic acid, 15d-prostaglandin J₂, and protectin D₁. This study reveals a previously unrecognized mechanism of CBM 588 and provides new insights into gut epithelial barrier protection with probiotics under conditions of antibiotic-induced dysbiosis.

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CBM 588 increases the abundance of Bifidobacterium, Lactobacillus, and Lactococcus

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Microbiota-driven TGF-β₁ controls the differentiation of lymphocytes to γδT cells

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CBM 588 promotes the expansion of IL-17A-producing γδT cells and CD4 cells

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CBM 588 upregulates anti-inflammatory lipid metabolites

Host inflammatory responses to intracellular invaders: Review study

As soon as a pathogen invades through the physical barriers of its corresponding host, host mounts a series of protective immune response to get rid of the invading pathogen. Host's pattern recognition receptors (PRR), localized at the cellular surface, cytoplasm and also in the nucleus; recognises pathogen associated molecular patterns (PAMPs) and plays crucial role in directing the immune response to be specific. Inflammatory responses are among the earliest strategies to tackle the pathogen by the host and are tightly regulated by multiple molecular pathways. Inflammasomes are multi-subunit protein complex consisting of a receptor molecule viz. NLRP3, an adaptor molecule- Apoptosis-associated speck-like protein containing a CARD (ASC) and an executioner caspase. Upon infection and/or injury; inflammasome components assemble and oligomerizes leading to the auto cleavage of the pro-caspase-1 to its active form. The activated caspase-1 cleaves immature form of the pro-inflammatory cytokines to their mature form e.g. IL1-β and IL-18 which mount inflammatory response. Moreover, C-terminal end of the Gasdermin D molecule is also cleaved by the caspase-1. The activated N-terminal Gasdermin D molecule form pores in the infected cells leading to their pyroptosis. Hence, inflammasomes drive inflammation during infection and controls the establishment of the pathogen by mounting inflammatory response and activation of the pyroptotic cell death.

Intermittent fasting improves metabolic flexibility in short-term high-fat diet-fed mice

Four days of high-fat diet (HFD) feeding are sufficient to induce glucose intolerance and hepatic steatosis in mice. While prolonged HFD-induced metabolic complications are partly mediated by increased food intake during the light (inactive) phase, such a link has not yet been established in short-term HFD-fed mice. Herein, we hypothesized that a short bout of HFD desynchronizes feeding behavior, thereby contributing to glucose intolerance and hepatic steatosis. To this end, 12-wk-old C57BL/6J littermates were fed a HFD for 4 days either ad libitum or intermittently. Intermittent-fed mice were fasted for 8 h during their inactive phase. Initiation of HFD led to an immediate increase in food intake already during the first light phase. Moreover, glucose tolerance was significantly impaired in ad libitum- but not in intermittent HFD-fed mice, indicating that desynchronized feeding behavior contributes to short-term HFD-induced glucose intolerance. Of note, overall food intake was similar between the groups, as was body weight. However, intermittent HFD-fed mice revealed higher fat depot weights. Phosphorylation of hormone sensitivity lipase and free fatty acid release from isolated adipocytes were significantly elevated, suggesting increased lipolysis in intermittent HFD-fed mice. Moreover, hepatic mRNA expression of lipogenetic enzymes and liver triglyceride levels were significantly increased in intermittent HFD-fed mice. Importantly, food deprivation decreased respiratory exchange ratio promptly in intermittent- but not in ad libitum HFD-fed mice. In conclusion, retaining a normal feeding pattern prevented HFD-induced impairment of metabolic flexibility in short-term HFD-fed mice.

Effects of PPAR-γ agonist, pioglitazone on brain tissues oxidative damage and learning and memory impairment in juvenile hypothyroid rats

Aim: The effect of peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist pioglitazone on the brain tissues oxidative damage and learning and memory impairment in the juvenile hypothyroid rats was evaluated. Main methods: Rats were classified as: ( 1 ) Control; (2) Propylthiouracil (PTU); (3) PTU-Pio 10 and (4) PTU-Pio 20. PTU was given in drinking water (0.05%) during 6 weeks. Pioglitazone (10 or 20 mg/kg) was daily injected intraperitoneally. Passive avoidance (PA) and Morris water maze (MMW) were conducted. Later, the animals were sacrificed and the brain tissues were removed for biochemical measurements. Key funding: The results indicated that in the MWM escape latency as well as traveled path increased in the PTU group as compared to the control group. Also, the time spent in the target quadrant in the probe test of MWM and step-through latency in the PA test were decreased in the PTU group as compared to the control group. Pioglitazone reversed all the negative behavioral effects of hypothyroidism. Administration of PTU attenuated thiol and superoxide dismutase (SOD), and catalase (CAT) activities in the brain tissues, whereas increased malondialdehyde (MDA) and nitric oxide (NO) metabolites. PPARγ agonist improved thiol, SOD and CAT, while diminished MDA concentration. Significance: Our finding in the present study indicated that PPARγ agonist pioglitazone prevented the brain tissues from oxidative damage and learning and memory impairments in juvenile hypothyroid rats.

Adipokines secretion in feline primary adipose tissue culture in response to dietary fatty acids

Background

Obesity in cats has been associated with alterations in adipokines including: adiponectin, interleukin-6 (IL6), and tumor necrosis factor-α (TNFα). Omega-3 polyunsaturated fatty acids have multiple beneficial effects on obesity-associated disorders, and therefore may alleviate these alterations. This study aimed to determine the effects of body condition, fat depot, troglitazone, and different fatty acids on secretion of adiponectin, IL6 and TNFα from adipose tissue of healthy cats. Subcutaneous and visceral adipose tissue samples were collected from 18 healthy intact female cats, and body condition score (Range 3–7/9) was determined. Concentrations of adiponectin were measured in mature adipocytes cultures and concentrations of IL6 and TNFα were measured in stromovascular cells cultures following treatment with control medium, troglitazone at 10 μM, eicosapentaenoic acid, arachidonic acid, or palmitic acid, at 25, 50, or 100 μM.

Results

Stromovascular cells of visceral origin secreted higher concentrations of IL6 than corresponding cells of subcutaneous origin (P = 0.003). Arachidonic acid treatment at 25, 50, and 100 μM increased IL6 secretion in subcutaneous (P = 0.045, P = 0.002, and P < 0.001, respectively) and visceral (P = 0.034, P = 0.001, and P < 0.001, respectively) stromovascular cells. Eicosapentaenoic acid treatment increased TNFα secretion in subcutaneous stromovascular cells at 25, 50, and 100 μM (P = 0.002, P = 0.001, and P = 0.015, respectively) and in visceral stromovascular cells at 50 μM (P < 0.001). No significant effect on medium adiponectin concentration was observed following troglitazone treatment (P = 0.4) or fatty acids treatments at 25 (P = 0.2), 50 (P = 0.8), or 100 (P = 0.7) μM. Body condition score did not have significant effects on medium concentrations of adiponectin (P = 0.4), IL6 (P = 0.1), or TNFα (P = 0.8).

Conclusions

This study demonstrated higher basal secretion of IL6 from visceral compared to subcutaneous adipose tissue, a stimulatory effect of arachidonic acid on secretion of IL6 and a stimulatory effect of eicosapentaenoic acid on TNFα from feline adipose tissue.

Molecular determinants for the polarization of macrophage and osteoclast

Emerging evidence suggest that macrophage and osteoclast are two competing differentiation outcomes from myeloid progenitors. In this review, we summarize recent advances in the understanding of the molecular mechanisms controlling the polarization of macrophage and osteoclast. These include nuclear receptors/transcription factors such as peroxisome proliferator-activated receptor γ (PPARγ) and estrogen-related receptor α (ERRα), their transcription cofactor PPARγ coactivator 1-β (PGC-1β), metabolic factors such as mitochondrial complex I (CI) component NADH:ubiquinone oxidoreductase iron-sulfur protein 4 (Ndufs4), as well as transmembrane receptors such as very-low-density-lipoprotein receptor (VLDLR). These molecular rheostats promote osteoclast differentiation but suppress proinflammatory macrophage activation and inflammation, by acting lineage-intrinsically, systemically or cross generation. These findings provide new insights to the understanding of the interactions between innate immunity and bone remodeling, advancing the field of osteoimmunology.

Pravastatin and Gemfibrozil Modulate Differently Hepatic and Colonic Mitochondrial Respiration in Tissue Homogenates from Healthy Rats

Statins and fibrates are widely used for the management of hypertriglyceridemia but they also have limitations, mostly due to pharmacokinetic interactions or side effects. It is conceivable that some adverse events like liver dysfunction or gastrointestinal discomfort are caused by mitochondrial dysfunction. Data about the effects of statins and fibrates on mitochondrial function in different organs are inconsistent and partially contradictory. The aim of this study was to investigate the effect of pravastatin (statin) and gemfibrozil (fibrate) on hepatic and colonic mitochondrial respiration in tissue homogenates. Mitochondrial oxygen consumption was determined in colon and liver homogenates from 48 healthy rats after incubation with pravastatin or gemfibrozil (100, 300, 1000 μM). State 2 (substrate dependent respiration) and state 3 (adenosine diphosphate: ADP-dependent respiration) were assessed. RCI (respiratory control index)—an indicator for coupling between electron transport chain system (ETS) and oxidative phosphorylation (OXPHOS) and ADP/O ratio—a parameter for the efficacy of OXPHOS, was calculated. Data were presented as a percentage of control (Kruskal–Wallis + Dunn’s correction). In the liver both drugs reduced state 3 and RCI, gemfibrozil-reduced ADP/O (complex I). In the colon both drugs reduced state 3 but enhanced ADP/O. Pravastatin at high concentration (1000 µM) decreased RCI (complex II). Pravastatin and gemfibrozil decrease hepatic but increase colonic mitochondrial respiration in tissue homogenates from healthy rats.

Docosahexaenoic acid inhibits hepatic stellate cell activation to attenuate liver fibrosis in a PPARγ-dependent manner

Docosahexaenoic acid (DHA) has been found to have a hepatoprotective effect. In this study, we investigated the role of peroxisome proliferator-activated receptor γ (PPARγ) in DHA regulation of liver fibrosis. DHA was found to inhibit hepatic stellate cell (HSC)-LX2 cell viability and downregulate marker proteins of HSC activation. Furthermore, DHA induced cell cycle arrest at G1 phase in HSCs. Antagonism of PPARγ by GW9662 abrogated the effects of DHA on HSCs. Computer-aided molecular docking predicted that DHA bound to PPARγ via hydrogen bonding with residues Ser289, His323, Tyr473, and His499. We overexpressed Ser289 mutant PPARγ in HSC-LX2 cells and investigated fibrotic marker modulation, and found that DHA effects on HSCs were diminished. Thus, bonding with the Ser289 residue might be indispensable for DHA to activate PPARγ to exert its inhibiting effect on activated HSCs. Last, data from a CCl₄-treated mouse model confirmed that PPARγ activation was required for DHA to attenuate liver fibrosis.

Its complicated: The relationship between alcohol and microglia in the search for novel pharmacotherapeutic targets for alcohol use disorders

Alcohol use disorder (AUD) is a chronic relapsing disorder with wide-ranging health consequences. Alcohol targets the central nervous system producing neurodegeneration and subsequent cognitive and behavioral deficits, but the mechanisms behind these effects remain unclear. Recently, evidence has been mounting for the role of neuroimmune activation in the pathogenesis of AUDs, but our nascent state of knowledge about the interaction of alcohol with the neuroimmune system supports that the relationship is complicated. As the resident macrophage of the central nervous system, microglia are a central focus. Human and animal research on the interplay between microglia and alcohol in AUDs has proven to be complex, and though early research focused on a pro-inflammatory phenotype of microglia, the anti-inflammatory and homeostatic roles of microglia must be considered. How these new roles for microglia should be incorporated into our thinking about the neuroimmune system in AUDs is discussed in the context of developing novel pharmacotherapies for AUDs.

2,4-Dinitrotoluene (DNT) Perturbs Yolk Absorption, Liver Development and Lipid Metabolism/Oxygen Transport Gene Expression in Zebrafish Embryos and Larvae

2,4-dinitrotoluene (2,4-DNT) is a common environmental pollutant, and was classified as a group 2B human carcinogenic compound by the International Agency for Research on Cancer. This study determined the toxic effects of 2,4-DNT exposure on zebrafish at the embryo-larvae stage, in terms of organ morphogenesis and the expression pattern of selected target genes related to lipid metabolism and oxygen transportation. The results showed that the 120-h post-fertilization LC50 of 2,4-DNT was 9.59 mg/L with a 95% confidence interval of 8.89-10.44 mg/L. The larvae treated with 2,4-DNT showed toxic symptoms including smaller body, less skin pigment production, yolk malabsorption, and disordered liver development. Further studies on the expression of genes related to lipid transport and metabolism, and respiration indicated that they were significantly affected by 2,4-DNT. It is concluded that 2,4-DNT exposure perturbed liver development and yolk absorption in early-life zebrafish, and disturbed the lipid metabolism /oxygen transport gene expression.

Engeletin inhibits Lipopolysaccharide/d-galactosamine-induced liver injury in mice through activating PPAR-γ

Liver injury is a serious clinical syndrome that characterized by inflammatory response. Engeletin is known to have anti-inflammatory activity. However, the effects of engeletin on liver injury remain unclear. We aimed to assess the protective effect of engeletin on Lipopolysaccharide (LPS)/d-galactosamine (D-gal)-induced liver injury in mice. Engeletin was administered intraperitoneally 1 h before and 12 h after LPS/D-gal treatment. The results showed that engeletin treatment on LPS/D-gal-induced liver injury in mice have a significant protective effect, as confirmed by the attenuation of liver histopathologic changes, MPO activity, and serum AST and ALT levels. At the meanwhile, it also showed that engeletin inhibited the levels of IL-β and TNF-α in serum and liver tissues. Besides, engeletin blocked the activation of NF-κB induced by LPS/D-gal and induced the expression of PPAR-γ in a dose-dependently manner. These findings suggested that engeletin may have a protective effect against liver injury.

New insights into acquired endocrine resistance of breast cancer

The translational research strategy of targeting estrogen receptor α (ERα) positive breast cancer and then using long term anti-hormone adjuvant therapy (5-10 years) has reduced recurrences and mortality. However, resistance continues to occur and improvements are required to build on the success of tamoxifen and aromatase inhibitors (AIs) established over the past 40 years. Further translational research has described the evolution of acquired resistance of breast cancer cell lines to long term estrogen deprivation that parallels clinical experience over years. Additionally, recent reports have identified mutations in the ERα obtained from the recurrences of AI treated patients. These mutations allow the ERα to activate without ligands and auto stimulate metastatic tumor growth. Furthermore, the new biology of estrogen-induced apoptosis in acquired resistant models in vitro and in vivo has been interrogated and applied to clinical trials. Inflammation and stress are emerging concepts occurring in the process of acquired resistance and estrogen-induced apoptosis with different mechanisms. In this review, we will present progress in the understanding of acquired resistance, focus on stress and inflammatory responses in the development of acquired resistance, and consider approaches to create new treatments to improve the treatment of breast cancer with endocrine resistance.

Bone Immune Response to Materials, Part II: Copper and Polyetheretherketone (PEEK) Compared to Titanium at 10 and 28 Days in Rabbit Tibia

Osseointegration is likely the result of an immunologically driven bone reaction to materials such as titanium. Osseointegration has resulted in the clinical possibility to anchor oral implants in jaw bone tissue. However, the mechanisms behind bony anchorage are not fully understood and complications over a longer period of time have been reported. The current study aims at exploring possible differences between copper (Cu) and polyetheretherketone (PEEK) materials that do not osseointegrate, with osseointegrating cp titanium as control. The implants were placed in rabbit tibia and selected immune markers were evaluated at 10 and 28 days of follow-up. Cu and PEEK demonstrated at both time points a higher immune activation than cp titanium. Cu demonstrated distance osteogenesis due to a maintained proinflammatory environment over time, and PEEK failed to osseointegrate due to an immunologically defined preferential adipose tissue formation on its surface. The here presented results suggest the description of two different mechanisms for failed osseointegration, both of which are correlated to the immune system.