A Novel Peroxisome Proliferator-activated Receptor (PPAR)γ Agonist 2-Hydroxyethyl 5-chloro-4,5-didehydrojasmonate Exerts Anti-Inflammatory Effects in Colitis

Forsythiaside A alleviates acute lung injury by inhibiting inflammation and epithelial barrier damages in lung and colon through PPAR-γ/RXR-α complex

INTRODUCTION

Acute lung injury (ALI) is a lung disease characterized by inflammation and still requires further drug development. Forsythiaside A as the active compound of Forsythiae Fructus has the therapeutic potential for ALI.

OBJECTIVE

To investigate the mechanism of forsythiaside A in treating ALI through PPAR-γ and its conjugate RXR-α based on gut-lung axis.

METHODS

This study constructed in vitro and in vivo injury models using LPS and TNF-α. Forsythiaside A was used for the drug treatment, and RXR-α inhibitor UVI3003 was used to interfere with PPAR-γ/RXR-α complexes in the cells. HE staining was used for histopathological examination. Serum endotoxin contents were determined using limulus lysate kit. IHC staining and Western blot were conducted to assess the protein expressions. ELISA was applied to examine the content of pro-inflammatory cytokines in the cell supernatants. The protein interactions were analyzed via CO-IP.

RESULTS

In vivo results showed that forsythiaside A regulated PPAR-γ/RXR-α and inhibited TLR4/MAPK/NF-κB and MLCK/MLC2 signal pathways, thus inhibiting inflammation and epithelial barrier damages of lung and colon in ALI mice induced by intratracheal LPS. PPAR-γ/RXR-α were promoted by forsythiaside A in lungs, whereas inhibited by forsythiaside A in colons. Additionally, in vitro results showed that forsythiaside A suppressed inflammation and epithelial barrier damages in macrophages and lung/colon epithelial cells, by manipulating PPAR-γ/RXR-α to suppress the LPS- and TNF-α-induced activation of TLR4/MAPK/NF-κB and NF-κB/MLCK/MLC2 signal pathways. Moreover, further mechanism study indicated that forsythiaside A showed a cell-specific regulatory effect on PPAR-γ/RXR-α complex. Specifically, the PPAR-γ/RXR-α protein interactions were promoted by forsythiaside A in LPS-induced macrophages RAW264.7 and TNF-α-induced lung epithelial cells A549, but inhibited by forsythiaside A in TNF-α-induced colon epithelial cells SW620.

CONCLUSION

In the treatment of ALI, Forsythiaside A inhibited inflammation and epithelial barrier damages of lung and colon through its regulation on PPAR-γ/RXR-α complex.

Unravelling the anti-inflammatory mechanism of Allium cepa: an integration of network pharmacology and molecular docking approaches

Allium cepa, commonly known as onion, is a widely consumed spice that possesses numerous pharmacological properties. A. cepa bioactive components are often explored in the treatment of inflammation-related complications. However, the molecular mechanism via which they exert their anti-inflammatory effects remains unknown. Therefore, this study aimed to elucidate the anti-inflammatory mechanism of A. cepa bioactive components. Consequently, the bioactive compounds of A. cepa were obtained from a database, while the potential targets of the sixty-nine compounds with desirable pharmacokinetic properties were predicted. Subsequently, the targets of inflammation were acquired from the GeneCards database. The protein-protein interaction (PPI) between the sixty-six shared targets of the bioactive compounds and inflammation was retrieved from the String database and visualized using Cytoscape v3.9.1 software. Gene Ontology (GO) analysis of the ten core targets from the PPI network revealed that A. cepa bioactive compounds could be involved in regulating biological processes such as response to oxygen-containing compounds and response to inflammation while Kyoto Encyclopaedia of Genes and Genomes (KEGG) analysis revealed that A. cepa compounds might modulate pathways including AGE-RAGE signaling pathway, interleukin (IL)-17 signalling pathway, and tumor necrosis factor signaling pathway. Molecular docking analysis showed that 1-O-(4-Coumaroyl)-beta-D-glucose, stigmasterol, campesterol, and diosgenin have high binding affinities for core targets including EGFR, ALB, MMP9, CASP3, and CCL5. This study successfully elucidated the potential anti-inflammatory mechanism of A. cepa bioactive compounds, hence, providing new insights into the development of alternative anti-inflammatory drugs.

Chicoric acid enhances the antioxidative defense system and protects against inflammation and apoptosis associated with the colitis model induced by dextran sulfate sodium in rats

Although several anticolitic drugs are available, their application is associated with numerous side effects. Chicoric acid (CA) is a hydroxycinnamic acid found naturally in chicory (Cichorium intybus), purple coneflower (Echinacea purpurea), and basil with numerous health benefits, such as antioxidative and anti-inflammatory activities. Here, the potential anticolitic efficiency of CA against dextran sulfate sodium (DSS)-induced colitis in rats was examined in rats. Animals were randomly assigned to the following five groups: control, CA (100 mg/kg body weight), DSS [(DSS); 4% w/v], CA + DSS (100 mg/kg), and the 5-aminosalicylic acid (100 mg/kg) + DSS group. The obtained data revealed that CA significantly prevented the shortening of colon length. Meanwhile, the oxidative stress-related enzymes were increased, while malondialdehyde and nitric oxide, were markedly decreased significantly by CA. The results also indicated that CA administration decreased significantly the pro-apoptogenic indices (Bax and caspase-3) and enhanced significantly Bcl-2, the anti-apoptogenic protein. Moreover, DSS caused a significant elevation of pro-inflammatory mediators, including interleukin-1β, tumor necrosis factor-α, myeloperoxidase, cyclooxygenase II, prostaglandin E2, and peroxisome proliferator-activated receptor gamma. Interestingly, these changes were significantly decreased following the CA administration. At the molecular level, CA supplementation has increased significantly the expression level of nuclear factor erythroid 2-related factor-2 (Nrf2) and decreased the expressions of nitric oxide synthase and mitogen-activated protein kinase 14. CA has been determined to significantly lessen DSS-induced colitis by activating Nrf2 and its derived antioxidant molecules and suppressing inflammation and apoptosis cascades associated with the development of colitis; suggesting that CA could be used as an alternative naturally-derived anticolitic agent.

Rosiglitazone Does Not Affect the Risk of Inflammatory Bowel Disease: A Retrospective Cohort Study in Taiwanese Type 2 Diabetes Patients

Human studies on the effect of rosiglitazone on inflammatory bowel disease (IBD) are still lacking. We investigated whether rosiglitazone might affect IBD risk by using the reimbursement database of Taiwan's National Health Insurance to enroll a propensity-score-matched cohort of ever users and never users of rosiglitazone. The patients should have been newly diagnosed with diabetes mellitus between 1999 and 2006 and should have been alive on 1 January 2007. We then started to follow the patients from 1 January 2007 until 31 December 2011 for a new diagnosis of IBD. Propensity-score-weighted hazard ratios were estimated with regards to rosiglitazone exposure in terms of ever users versus never users and in terms of cumulative duration and cumulative dose of rosiglitazone therapy for dose-response analyses. The joint effects and interactions between rosiglitazone and risk factors of psoriasis/arthropathies, dorsopathies, and chronic obstructive pulmonary disease/tobacco abuse and the use of metformin were estimated by Cox regression after adjustment for all covariates. A total of 6226 ever users and 6226 never users were identified and the respective numbers of incident IBD were 95 and 111. When we compared the risk of IBD in ever users to that of the never users, the estimated hazard ratio (0.870, 95% confidence interval: 0.661-1.144) was not statistically significant. When cumulative duration and cumulative dose of rosiglitazone therapy were categorized by tertiles and hazard ratios were estimated by comparing the tertiles of rosiglitazone exposure to the never users, none of the hazard ratios reached statistical significance. In secondary analyses, rosiglitazone has a null association with Crohn's disease, but a potential benefit on ulcerative colitis (UC) could not be excluded. However, because of the low incidence of UC, we were not able to perform detailed dose-response analyses for UC. In the joint effect analyses, only the subgroup of psoriasis/arthropathies (-)/rosiglitazone (-) showed a significantly lower risk in comparison to the subgroup of psoriasis/arthropathies (+)/rosiglitazone (-). No interactions between rosiglitazone and the major risk factors or metformin use were observed. We concluded that rosiglitazone has a null effect on the risk of IBD, but the potential benefit on UC awaits further investigation.

Atractylodin Ameliorates Colitis via PPARα Agonism

Atractylodin is a major compound in the rhizome of Atractylodes lancea, an oriental herbal medicine used for the treatment of gastrointestinal diseases, including dyspepsia, nausea, and diarrhea. Recent studies have shown that atractylodin exerts anti-inflammatory effects in various inflammatory diseases. Herein, we investigated the anti-colitis effects of atractylodin and its molecular targets. We determined the non-cytotoxic concentration of atractylodin (50 μM) using a cell proliferation assay in colonic epithelial cells. We found that pretreatment with atractylodin significantly inhibits tumor necrosis factor-α-induced phosphorylation of nuclear factor-κ-light-chain-enhancer of activated B in HCT116 cells. Through docking simulation analysis, luciferase assays, and in vitro binding assays, we found that atractylodin has an affinity for peroxisome proliferator-activated receptor alpha (PPARα). Daily administration of atractylodin (40 mg/kg) increased the survival rate of mice in a dextran sodium sulfate-induced colitis mouse model. Thus, atractylodin can be a good strategy for colitis therapy through inducing PPARα-dependent pathways.

Therapeutic Effects of Retinoic Acid in Lipopolysaccharide-Induced Cardiac Dysfunction: Network Pharmacology and Experimental Validation

Purpose

Sepsis, which is deemed as a systemic inflammation reaction syndrome in the face of infectious stimuli, is the primary cause of death in ICUs. Sepsis-induced cardiomyopathy (SIC) may derive from systemic inflammation reaction and oxidative stress. Retinoic acid (RA) is recognized by its beneficial roles in terms of the immunoresponse to infections and antioxygen actions. However, the treatment efficacy and potential causal links of RA in SIC are still elusive.

Methods

By virtue of the STITCH database, we identified the targets of RA. Differentially expressed genes in SIC were acquired from the GEO database. The PPI network of intersected targets was established. GO and KEGG pathway enrichment analysis was completed. Hub genes were analyzed by cytoHubba plug-in. In the process of experimental validation, a mouse sepsis model was established by lipopolysaccharide (LPS), and the treated mice were intraperitoneally injected with RA or Dexamethasone (DEX) 60 min prior to LPS injections. Survival conditions, cardiac functions and antioxidant levels of the mice were assessed. Cardiac inflammation and injury were detected by HE and TUNEL. The levels of key genes and signal pathway expression were analyzed by RT-PCR and Western blot.

Results

PPARA, ITGAM, VCAM-1, IGF-1 and IL-6 were identified as key therapeutic targets of RA by network pharmacology. PI3K-Akt signaling pathway is the main regulatory pathway of RA. In vivo researches unraveled that RA can improve the survival rate and cardiac function of LPS-treated mice, inhibit inflammatory factors and myocardial injury, and regulate the expression of key therapeutic targets and key pathways, which is PI3K-Akt signaling pathway.

Conclusion

Network pharmacological method offers a predicative strategy to explore the treatment efficacy and causal links of RA in endotoxemic myocarditis. Through experimental verification, we discover that RA can reduce lipopolysaccharide-induced cardiac dysfunction by regulating the PI3K-Akt signaling pathway and key genes.

Integrated bioinformatics and network pharmacology to identify the therapeutic target and molecular mechanisms of Huangqin decoction on ulcerative Colitis

Huangqin decoction (HQD) is a Traditional Chinese Medicine formula for ulcerative colitis. However, the pharmacology and molecular mechanism of HQD on ulcerative colitis is still unclear. Combined microarray analysis, network pharmacology, and molecular docking for revealing the therapeutic targets and molecular mechanism of HQD against ulcerative colitis. TCMSP, DrugBank, Swiss Target Prediction were utilized to search the active components and effective targets of HQD. Ulcerative colitis effective targets were obtained by microarray data from the GEO database (GSE107499). Co-targets between HQD and ulcerative colitis are obtained by Draw Venn Diagram. PPI (Protein–protein interaction) network was constructed by the STRING database. To obtain the core target, topological analysis is exploited by Cytoscape 3.7.2. GO and KEGG enrichment pathway analysis was performed to Metascape platform, and molecular docking through Autodock Vina 1.1.2 finished. 161 active components with 486 effective targets of HQD were screened. 1542 ulcerative colitis effective targets were obtained with |Log₂FC|> 1 and adjusted P-value < 0.05. The Venn analysis was contained 79 co-targets. Enrichment analysis showed that HQD played a role in TNF signaling pathway, IL-17 signaling pathway, Th17 cell differentiation, etc. IL6, TNF, IL1B, PTGS2, ESR1, and PPARG with the highest degree from PPI network were successfully docked with 19 core components of HQD, respectively. According to ZINC15 database, quercetin (ZINC4175638), baicalein (ZINC3871633), and wogonin (ZINC899093) recognized as key compounds of HQD on ulcerative colitis. PTGS2, ESR1, and PPARG are potential therapeutic targets of HQD. HQD can act on multiple targets through multi-pathway, to carry out its therapeutic role in ulcerative colitis.

Zinc and Selenium in Inflammatory Bowel Disease: Trace Elements with Key Roles?

Inflammatory bowel disease (IBD) is a chronic inflammatory condition that may emerge at a young age and often lasts for life. It often goes through phases of recurrence and remission and has a devastating effect on quality of life. The exact etiology of the disease is still unclear, but it appears that an inappropriate immune response to intestinal flora bacteria in people with a genetic predisposition may cause the disease. Managing inflammatory bowel disease is still a serious challenge. Oxidative stress and free radicals appear to be involved in the pathogenesis of this disease, and a number of studies have suggested the use of antioxidants as a therapeutic approach. The antioxidant and anti-inflammatory properties of some trace elements have led some of the research to focus on studying these trace elements in inflammatory bowel disease. Zinc and selenium are among the most important trace elements that have significant anti-inflammatory and antioxidant properties. Some studies have shown the importance of these trace elements in inflammatory bowel disease. In this review, we have attempted to provide a comprehensive overview of the findings of these studies and to gather current knowledge about the association of these trace elements with the inflammatory process and inflammatory bowel disease.

High-Fat Diet Induces Inflammation of Meibomian Gland

Purpose

To determine if a high-fat diet (HFD) induces meibomian gland (MG) inflammation in mice.

Methods

Male C57BL/6J mice were fed a standard diet (SD), HFD, or HFD supplemented with the peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist rosiglitazone for various durations. Body weight, blood lipid levels, and eyelid changes were monitored at regular intervals. MG sections were subjected to hematoxylin and eosin staining, LipidTox staining, TUNEL assay, and immunostaining. Quantitative RT-PCR and western blot analyses were performed to detect relative gene expression and signaling pathway activation in MGs.

Results

MG acinus accumulated more lipids in the mice fed the HFD. Periglandular CD45-positive and F4/80-positive cell infiltration were more evident in the HFD mice, and they were accompanied by upregulation of inflammation-related cytokines. PPAR-γ downregulation accompanied activation of the mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways in the HFD mice. There was increased acini cell apoptosis and mitochondria damage in mice fed the HFD. MG inflammation was ameliorated following a shift to the standard diet and rosiglitazone treatment in the mice fed the HFD.

Conclusions

HFD-induced declines in PPAR-γ expression and MAPK and NF-κB signaling pathway activation resulted in MG inflammation and dysfunction in mice.

Peroxisome Proliferator-Activated Receptor-Gamma (PPAR-ɣ): Molecular Effects and Its Importance as a Novel Therapeutic Target for Cerebral Ischemic Injury

Cerebral ischemic injury is a leading cause of death and long-term disability throughout the world. Peroxisome proliferator-activated receptor gamma (PPAR-ɣ) is a ligand-activated nuclear transcription factor that is a member of the PPAR family. PPAR-ɣ has been shown in several in vitro and in vivo models to prevent post-ischemic inflammation and neuronal damage by negatively controlling the expression of genes modulated by cerebral ischemic injury, indicating a neuroprotective effect during cerebral ischemic injury. A extensive literature review of PubMed, Medline, Bentham, Scopus, and EMBASE (Elsevier) databases was carried out to understand the nature of the extensive work done on the mechanistic role of Peroxisome proliferator activated receptor gamma and its modulation in Cerebral ischemic injury. PPAR-ɣ can interact with specific DNA response elements to control gene transcription and expression when triggered by its ligand. It regulates lipid metabolism, improves insulin sensitivity, modulates antitumor mechanisms, reduces oxidative stress, and inhibits inflammation. This review article provides insights on the current state of research into the neuroprotective effects of PPAR-ɣ in cerebral ischemic injury, as well as the cellular and molecular mechanisms by which these effects are modulated, such as inhibition of inflammation, reduction of oxidative stress, suppression of pro-apoptotic production, modulation of transcription factors, and restoration of injured tissue through neurogenesis and angiogenesis.

Heterodimer formation with retinoic acid receptor RXRα modulates coactivator recruitment by peroxisome proliferator-activated receptor PPARγ

Nuclear receptors (NRs) activate transcription of target genes in response to binding of ligands to their ligand-binding domains (LBDs). Typically, in vitro assays use either gene expression or the recruitment of coactivators to the isolated LBD of the NR of interest to measure NR activation. However, this approach ignores that NRs function as homo- as well as heterodimers and that the LBD harbors the main dimerization interface. Cofactor recruitment is thereby interconnected with oligomerization status as well as ligand occupation of the partnering LBD through allosteric cross talk. Here we present a modular set of homogeneous time-resolved FRET-based assays through which we investigated the activation of PPARγ in response to ligands and the formation of heterodimers with its obligatory partner RXRα. We introduced mutations into the RXRα LBD that prevent coactivator binding but do not interfere with LBD dimerization or ligand binding. This enabled us to specifically detect PPARγ coactivator recruitment to PPARγ:RXRα heterodimers. We found that the RXRα agonist SR11237 destabilized the RXRα homodimer but promoted formation of the PPARγ:RXRα heterodimer, while being inactive on PPARγ itself. Of interest, incorporation of PPARγ into the heterodimer resulted in a substantial gain in affinity for coactivator CBP-1, even in the absence of ligands. Consequently, SR11237 indirectly promoted coactivator binding to PPARγ by shifting the oligomerization preference of RXRα toward PPARγ:RXRα heterodimer formation. These results emphasize that investigation of ligand-dependent NR activation should take NR dimerization into account. We envision these assays as the necessary assay tool kit for investigating NRs that partner with RXRα.

Bacteria-derived long chain fatty acid exhibits anti-inflammatory properties in colitis

OBJECTIVE

Data from clinical research suggest that certain probiotic bacterial strains have the potential to modulate colonic inflammation. Nonetheless, these data differ between studies due to the probiotic bacterial strains used and the poor knowledge of their mechanisms of action.

DESIGN

By mass-spectrometry, we identified and quantified free long chain fatty acids (LCFAs) in probiotics and assessed the effect of one of them in mouse colitis.

RESULTS

Among all the LCFAs quantified by mass spectrometry in Escherichia coli Nissle 1917 (EcN), a probiotic used for the treatment of multiple intestinal disorders, the concentration of 3-hydroxyoctadecaenoic acid (C18-3OH) was increased in EcN compared with other E. coli strains tested. Oral administration of C18-3OH decreased colitis induced by dextran sulfate sodium in mice. To determine whether other bacteria composing the microbiota are able to produce C18-3OH, we targeted the gut microbiota of mice with prebiotic fructooligosaccharides (FOS). The anti-inflammatory properties of FOS were associated with an increase in colonic C18-3OH concentration. Microbiota analyses revealed that the concentration of C18-3OH was correlated with an increase in the abundance in Allobaculum, Holdemanella and Parabacteroides. In culture, Holdemanella biformis produced high concentration of C18-3OH. Finally, using TR-FRET binding assay and gene expression analysis, we demonstrated that the C18-3OH is an agonist of peroxisome proliferator activated receptor gamma.

CONCLUSION

The production of C18-3OH by bacteria could be one of the mechanisms implicated in the anti-inflammatory properties of probiotics. The production of LCFA-3OH by bacteria could be implicated in the microbiota/host interactions.

Inflammatory Bowel Disease: New Insights into the Interplay between Environmental Factors and PPARγ

The pathophysiological processes of inflammatory bowel diseases (IBDs), i.e., Crohn's disease (CD) and ulcerative colitis (UC), are still not completely understood. The exact etiology remains unknown, but it is well established that the pathogenesis of the inflammatory lesions is due to a dysregulation of the gut immune system resulting in over-production of pro-inflammatory cytokines. Increasing evidence underlines the involvement of both environmental and genetic factors. Regarding the environment, the microbiota seems to play a crucial role. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors that exert pleiotropic effects on glucose homeostasis, lipid metabolism, inflammatory/immune processes, cell proliferation, and fibrosis. Furthermore, PPARs modulate interactions with several environmental factors, including microbiota. A significantly impaired PPARγ expression was observed in UC patients' colonic epithelial cells, suggesting that the disruption of PPARγ signaling may represent a critical step of the IBD pathogenesis. This paper will focus on the role of PPARγ in the interaction between environmental factors and IBD, and it will analyze the most suitable in vitro and in vivo models available to better study these relationships.

Blockage of protease-activated receptor 2 exacerbates inflammation in high-fat environment partly through autophagy inhibition

Protease-activated receptor 2 (PAR2) regulates inflammatory responses and lipid metabolism. However, its precise role in colitis remains unclear. In this study, we aimed to investigate the function of PAR2 in high-fat diet-fed mice with colitis and its potential role in autophagy. PAR2^+/+ and PAR2^-/- mice were fed a high-fat diet (HFD) for 7 days before colitis induction with dextran sodium sulfate. Deletion of PAR2 and an HFD significantly exacerbated colitis, as shown by increased mortality, body weight loss, diarrhea or bloody stools, colon length shortening, and mucosal damage. Proinflammatory cytokine levels were elevated in HFD-fed PAR2^-/- mice and in cells treated with the PAR2 antagonist GB83, palmitic acid (PA), and a cytokine cocktail (CC). Damaging effects of PAR2 blockage were associated with autophagy regulation by reducing the levels of YAP1, SIRT1, PGC-1α, Atg5, and LC3A/B-I/II. In addition, mitochondrial dysfunction was demonstrated only in cells treated with GB83, PA, and CC. Reduced cell viability and greater induction of apoptosis, as shown by increased levels of cleaved caspase-9, cleaved caspase-3, and cleaved poly(ADP-ribose) polymerase (PARP), were observed in cells treated with GB83, PA, and CC but not in those treated with only PA and CC. Collectively, protective effects of PAR2 were elucidated during inflammation accompanied by a high-fat environment by promoting autophagy and inhibiting apoptosis, suggesting PAR2 as a therapeutic target for inflammatory bowel disease co-occurring with metabolic syndrome.NEW & NOTEWORTHY Deletion of PAR2 with high-fat diet feeding exacerbates colitis in a murine colitis model. Proinflammatory effects of PAR2 blockage in a high-fat environment were associated with an altered balance between autophagy and apoptosis. Increased colonic levels of PAR2 represent as a therapeutic strategy for IBD co-occurring with metabolic syndrome.

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.

Catalpol ameliorates doxorubicin-induced inflammation and oxidative stress in H9C2 cells through PPAR-γ activation

Drug-induced cardiomyopathy is a severe disease that leads to refractory heart disease at late stages, with increasing detrimental effects. DOX-induced cell damage is primarily induced via cellular oxidative stress. The present study investigated the effects of catalpol on doxorubicin (DOX)-induced H9C2 cardiomyocyte inflammation and oxidative stress. The Cell Counting Kit-8 assay was performed to detect cell viability, and western blotting was performed to detect the expression of peroxisome proliferator-activated receptor (PPAR)-γ in H9C2 cells. The expression levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6 were measured using ELISAs. Furthermore, the oxidative stress kit was used to detect the levels of malondialdehyde, superoxide dismutase and glutathione peroxidase. A reactive oxygen species (ROS) kit and DCF-DA staining were used to detect ROS levels. The results indicated that DOX treatment inhibited H9C2 cell expression of PPAR-γ and decreased H9C2 cell viability. Various concentrations of catalpol exhibited a less potent effect on H9C2 cell viability compared with DOX; however, catalpol increased the viability of DOX-induced H9C2 cells. Catalpol treatment also significantly decreased the expression levels of inflammatory factors (TNF-α, IL-1β and IL-6) in DOX-induced H9C2 cells, which was reversed by transfections with short hairpin RNA targeting PPAR-γ. Results from the present study indicated that catalpol ameliorated DOX-induced inflammation and oxidative stress in H9C2 cardiomyoblasts by activating PPAR-γ.

Phytochemical drug candidates for the modulation of peroxisome proliferator-activated receptor γ in inflammatory bowel diseases

Plant-based compounds or phytochemicals such as alkaloids, glycosides, flavonoids, volatile oils, tannins, resins, and polyphenols have been used extensively in traditional medicine for centuries and more recently in Western alternative medicine. Extensive evidence suggests that consumption of dietary polyphenolic compounds lowers the risk of inflammatory diseases. The anti-inflammatory properties of several phytochemicals are mediated through ligand-inducible peroxisome proliferator-activated receptors (PPARs), particularly the PPARγ transcription factor. Inflammatory bowel disease (IBD) is represented by ulcerative colitis, which occurs in the mucosa of the colon and rectum, and Crohn's disease (CD) that can involve any segment of gastrointestinal tract. Because of the lack of cost-effective pharmaceutical treatment options, many IBD patients seek and use alternative and unconventional therapies to alleviate their symptoms. PPARγ plays a role in the inhibition of inflammatory cytokine expression and activation of anti-inflammatory immune cells. The phytochemicals reported here are ligands that activate PPARγ, which in turn modulates inflammatory responses. PPARγ is highly expressed in the gut making it a potential therapeutic target for IBDs. This review summarizes the effects of the currently published phytochemicals that modulate the PPARγ pathway and reduce or eliminate colonic inflammation.

Gabapentin attenuates intestinal inflammation: Role of PPAR-gamma receptor

Gabapentin is an anticonvulsant drug that is also used for post-herpetic neuralgia and neuropathic pain. Recently, gabapentin showed anti-inflammatory effect. Nuclear factor kappa B (NFκB) is a regulator of the inflammatory process, and Peroxisome Proliferator-activated Receptor gamma (PPAR-gamma) is an important receptor involved in NFκB regulation. The aim of the present work was to study the potential role of PPAR-gamma receptor in gabapentin-mediated anti-inflammatory effects in a colitis experimental model. We induced colitis in rats using trinitrobenzenosulfonic acid and treated them with gabapentin and bisphenol A dicyldidyl ether (PPAR-gamma inhibitor). Macroscopic lesion scores, wet weight, histopathological analysis, mast cell count, myeloperoxidase, malondialdehyde acid, glutathione, nitrate/nitrite, and interleukin levels in the intestinal mucosa were determined. In addition, western blots were performed to determine the expression of Cyclooxygenase-2 (COX-2) and NFκB; Nitric Oxide Inducible Synthase (iNOS) and Interleukin 1 beta (IL-1β) levels were also determined. Gabapentin was able to decrease all inflammatory parameters macroscopic and microscopic in addition to reducing markers of oxidative stress and cytokines such as IL-1β and Tumor Necrosis Factor alpha (TNF-α) as well as enzymes inducible nitric oxide synthase and cyclooxygenase 2 and inflammatory genic regulator (NFκB). These effect attributed to gabapentin was observed to be lost in the presence of the specific inhibitor of PPAR-gamma. Gabapentin inhibits bowel inflammation by regulating mast cell signaling. Furthermore, it activates the PPAR-gamma receptor, which in turn inhibits the activation of NFκB, and consequently results in reduced activation of inflammatory genes involved in inflammatory bowel diseases.

Elevated faecal 12,13-diHOME concentration in neonates at high risk for asthma is produced by gut bacteria and impedes immune tolerance

Neonates at risk of childhood atopy and asthma exhibit perturbation of the gut microbiome, metabolic dysfunction and increased concentrations of 12,13-diHOME in their faeces. However, the mechanism, source and contribution of this lipid to allergic inflammation remain unknown. Here, we show that intra-abdominal treatment of mice with 12,13-diHOME increased pulmonary inflammation and decreased the number of regulatory T (T_reg) cells in the lungs. Treatment of human dendritic cells with 12,13-diHOME altered expression of PPARγ-regulated genes and reduced anti-inflammatory cytokine secretion and the number of T_reg cells in vitro. Shotgun metagenomic sequencing of neonatal faeces indicated that bacterial epoxide hydrolase (EH) genes are more abundant in the gut microbiome of neonates who develop atopy and/or asthma during childhood. Three of these bacterial EH genes (3EH) specifically produce 12,13-diHOME, and treatment of mice with bacterial strains expressing 3EH caused a decrease in the number of lung T_reg cells in an allergen challenge model. In two small birth cohorts, an increase in the copy number of 3EH or the concentration of 12,13-diHOME in the faeces of neonates was found to be associated with an increased probability of developing atopy, eczema or asthma during childhood. Our data indicate that elevated 12,13-diHOME concentrations impede immune tolerance and may be produced by bacterial EHs in the neonatal gut, offering a mechanistic link between perturbation of the gut microbiome during early life and atopy and asthma during childhood.

Aesculin protects against DSS-Induced colitis though activating PPARγ and inhibiting NF-кB pathway

Aesculin, a natural product from the traditional and widely-used Chinese medicine named Cortex fraxini, has attracted attention as a novel therapeutic modulator of inflammation. However, little is known about its effect on ulcerative colitis (UC). This study aimed to investigate the protective effects and mechanisms of aesculin on colitis. The results showed that, few cytotoxicity of aesculin were shown in vivo and in the RAW264.7 macrophages, while aesculin significantly relieved the symptoms of DSS-induced colitis and restrained the expression of inflammatory factors including iNOS, IL-1β, TNF-α in both peritoneal macrophages and colonic tissues from DSS-induced mice and RAW264.7 macrophages. Of note, aesculin attenuated the activity of NF-κB signaling while promoted the nuclear localization of PPAR-γ in both rectal tissues from DSS-induced mice and LPS-stimulated macrophages. These findings demonstrated that the protection of aesculin against ulcerative colitis might be due to its regulation on the PPAR-γ and NF-κB pathway. Thus, aesculin could serve as a potential therapeutic agent for the treatment of ulcerative colitis.

CCL20-CCR6 axis modulated traumatic brain injury-induced visual pathologies

BACKGROUND

Traumatic brain injury (TBI) is a major cause of death and disability in the USA and the world; it constitutes 30% of injury-related deaths (Taylor et al., MMWR Surveill Summ 66:1-16, 2017). Contact sports athletes often experience repetitive TBI (rTBI), which exerts a cumulative effect later in life. Visual impairment is a common after-effect of TBI. Previously, we have shown that C-C chemokine 20 (CCL20) plays a critical role in neurodegeneration and inflammation following TBI (Das et al., J Neuroinflammation 8:148, 2011). C-C chemokine receptor 6 (CCR6) is the only receptor that CCL20 interacts with. The objective of the present study was to investigate the role of CCL20-CCR6 axis in mediating rTBI-induced visual dysfunction (TVD).

METHODS

Wild type (WT) or CCR6 knock out (CCR6-/-) mice were subjected to closed head rTBI. Pioglitazone (PG) is a peroxisome proliferator-activated receptor γ (PPARγ) agonist which downregulates CCL20 production. Subsets of WT mice were treated with PG following final rTBI. A subset of mice was also treated with anti-CCL20 antibody to neutralize the CCL20 produced after rTBI. Histopathological assessments were performed to show cerebral pathologies, retinal pathologies, and inflammatory changes induced by rTBI.

RESULTS

rTBI induced cerebral neurodegeneration, retinal degeneration, microgliosis, astrogliosis, and CCL20 expression. CCR6-/- mice showed reduced retinal degeneration, microgliosis, and inflammation. Treatment with CCL20 neutralization antibody or PG showed reduced CCL20 expression along with reduced retinal degeneration and inflammation. rTBI-induced GFAP-positive glial activation in the optic nerve was not affected by knocking out CCR6.

CONCLUSION

The present data indicate that rTBI-induced retinal pathology is mediated at least in part by CCL20 in a CCR6-dependent manner.

Nuclear Receptors in the Pathogenesis and Management of Inflammatory Bowel Disease

Nuclear receptors (NRs) are ligand-dependent transcription factors that regulate the transcription of target genes. Previous epidemiological and genetic studies have documented the association of NRs with the risk of inflammatory bowel disease (IBD). Although the mechanisms of action of NRs in IBD have not been fully established, accumulating evidence has demonstrated that NRs play complicated roles in regulating intestinal immunity, mucosal barriers, and intestinal flora. As one of the first-line medications for the treatment of IBD, 5-aminosalicylic acid (5-ASA) activates peroxisome proliferator-activated receptor gamma (PPARγ) to attenuate colitis. The protective roles of rifaximin and rifampicin partly depend on promoting pregnane X receptor (PXR) expression. The aims of this review are to discuss the roles of several important NRs, such as PPARγ, PXR, vitamin D receptor (VDR), farnesoid X receptor (FXR), and RAR-related orphan receptor gammat (RORγt), in the pathogenesis of IBD and management strategies based on targeting these receptors.

B-cell-specific-peroxisome proliferator-activated receptor γ deficiency augments contact hypersensitivity with impaired regulatory B cells

Nuclear receptor peroxisome proliferator-activated receptor γ (PPAR-γ) activation can prevent immunoinflammatory disorders and diabetes. B cells play protective roles during inflammation as well. However, the roles of endogenous PPAR-γ in the regulatory properties of B cells to relieve inflammation remain unknown. Here, we developed B-cell-specific PPAR-γ knockout (B-PPAR-γ^-/- ) mice and found that the conditional deletion of PPAR-γ in B cells resulted in exaggerated contact hypersensitivity (CHS). Meanwhile, interferon-γ (IFN-γ) of CD4⁺ CD8⁺ T cells was up-regulated in B-PPAR-γ^-/- mice in CHS. This showed that the regulatory function of B cells in B-PPAR-γ^-/- mice declined in vivo. Whereas splenic CD5⁺ CD1d^hi regulatory B-cell numbers and peripheral regulatory T-cell numbers were not changed in naive B-PPAR-γ^-/- mice. Loss of PPAR-γ in B cells also did not affect either CD86 or FasL expression in splenic CD5⁺ CD1d^hi regulatory B cells after activation. Notably, interleukin-10 (IL-10) production in CD5⁺ CD1d^hi regulatory B cells reduced in B-PPAR-γ-deficient mice. In addition, functional IL-10-producing CD5⁺ CD1d^hi regulatory B cells decreased in B-PPAR-γ^-/- mice in the CHS model. These findings were in accordance with augmented CHS. The current work indicated the involvement of endogenous PPAR-γ in the regulatory function of B cells by disturbing the expansion of IL-10-positive regulatory B cells.

An update on dietary consideration in inflammatory bowel disease: anthocyanins and more

Inflammatory bowel disease (IBD) is a chronic idiopathic inflammatory disorder. A wealth of data pointed out that various aspects of chronic inflammation may be affected by several specific dietary factors. This paper calls attention to anthocyanins enriched plant food and anthocyanin dietary supplements, whose role in the management of IBD and its associated oncogenesis deems crucial. Area covered: We updated the most relevant dietary anthocyanins with potential anti-colitis and preventive effect on inflammatory associated colorectal cancer based on the recent animal and human researches along with revealing the major cellular and molecular mechanisms of action. Mounting evidence reported that anthocyanins enriched plant foods perform their protective role on IBD and inflammatory-induced colorectal cancer via different cellular transduction signaling pathways, including inflammatory transcription factors, SAPK/JNK and p38 MAPK cascade, JAK/STAT signaling, NF-kB/pERK/MAPK, Wnt signaling pathway, Nrf2 cytoprotective pathway as well as AMPK pathway and autophagy. Expert commentary: Combination of anthocyanins enriched dietary supplements with existing medications can provide new therapeutic options for IBD patients. Further, well-designed randomized control trials (RCTs) are essential to evaluate the role of anthocyanins enriched medicinal foods as well as isolated anthocyanin components as promising preventive and therapeutic dietary agents for IBD and its associated oncogenesis.

Senescence marker protein 30 protects intestinal epithelial cells against inflammation-induced cell death by enhancing Nrf2 activity

Senescence marker protein 30 (SMP30) is a calcium-binding protein whose expression decreases during senescence. SMP30 deficiency increases susceptibility to cytokine-induced apoptosis in the liver and to radiation-induced apoptosis in the small intestine. Furthermore, colonic epithelial cell death is associated with the severity of colitis. Therefore, in the present study, we investigated the function of SMP30 during intestinal inflammation. In SMP30 deficient mice, colitis was significantly exacerbated as demonstrated by increased mortality (p = 0.001), body weight loss (p = 0.0105 at day 8), rectal bleeding (p = 0.0047 at day 8) and diarrhea (p = 0.0030 at day 8), histological scores (ulcers, p = 0.0002; edema, p = 0.0125; leukocyte infiltration, p = 0.0016) and productions of pro-inflammatory cytokines (IL-1α, p = 0.0452; IL-6, p = 0.0074; G-CSF, p = 0.0036). In addition, greater proportions of apoptotic cells and lower levels of anti-apoptotic marker proteins (total PARP-1 and Bcl-2) were observed in the inflamed intestines of SMP30 deficient mice than in wild type controls. In vitro experiments on colonic epithelial cells showed that stable SMP30 expression inhibited but that SMP30 siRNA expression increased TNF-α-induced apoptosis. SMP30 inhibition decreased Nrf2 mRNA expression levels (p < 0.0001), but SMP30 overexpression increased Nrf2 mRNA expression levels (p = 0.0495). The underlying mechanism by which SMP30 protected cells appeared to be by inhibiting Nrf2 ubiquitination and Keap1 expression, and thus enhancing Nrf2 activity. Moreover, SMP30 deficiency increased the incidence of colitis-associated colon cancer as determined by increased mortality (p = 0.0572) and average polyp number (p = 0.0277). Collectively, these findings suggest that SMP30 protects intestinal epithelial cells from apoptosis and this can contribute to amelioration of colitis and colitis-associated colon cancer.

Novel SIRT1 inhibitor 15-deoxy-Δ12,14-prostaglandin J2 and its derivatives exhibit anticancer activity through apoptotic or autophagic cell death pathways in SKOV3 cells

Clinically relevant sirtuin (SIRT) inhibitors may possess antitumor activities. A previous study indicated that 15-deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂) exhibited potent anticancer activity by SIRT1 inhibition. Therefore, the aim of the present study was to investigate whether its derivatives (J11-C1 and J19) exhibited anticancer activity against ovarian cancer SKOV3 cells. Cell viability was determined using an MTT assay. Cell cycle arrest, apoptosis and autophagy were determined using flow cytometry or western blot analysis. J11-Cl and J19 were less cytotoxic to SKOV3 cells compared with 15d-PGJ₂. Molecular docking studies supported the interactions of 15d-PGJ₂, J11-Cl and J19 with various amino acids in SIRT1 proteins. Similar to 15d-PGJ₂, J11-C1 and J19 inhibited SIRT1 enzymatic activity and decreased SIRT1 expression levels in a concentration-dependent manner. J11-C1 induced apoptotic cell death more effectively compared with J19, which was associated with markedly decreased expression of the anti-apoptotic molecule B-cell lymphoma 2 (Bcl-2). Furthermore, the levels of light chain 3-II (LC3-II) and beclin-1 were clearly induced in SKOV3 cells treated with J11-Cl. Thus, 15d-PGJ₂ and its derivatives exhibited anticancer activity possibly by inducing apoptotic or autophagic cell death pathways. Collectively, the results of the present study suggest that 15d-PGJ₂ and its derivatives exerted antitumor activity by selectively modulating the expression of genes associated with cell cycle arrest, apoptosis and autophagy. Notably, J11-C1 is a novel candidate SIRT1 inhibitor with anticancer activity.

Design of PPAR-γ agonist based on algal metabolites and the endogenous ligand 15-deoxy-Δ12, 14-prostaglandin J2

In a previous study, we synthesized endocyclic enone jasmonate derivatives that function as anti-inflammatory and PPAR-γ-activating entities by using key functional moieties of anti-inflammatory algal metabolites. Herein, we designed additional derivatives containing an exocyclic enone moiety that resembles the key structure of the natural PPAR-γ ligand, 15-deoxy-Δ^{12, 14}-prostaglandin J₂ (15 d-PGJ₂). The exocyclic enone moiety of 15 d-PGJ₂ is essential for covalent bonding with the Cys²⁸⁵ residue in the PPAR-γ ligand-binding domain (LBD). In silico analysis of the designed compounds indicated that they may form hydrogen bonds with key amino acid residues in the PPAR-γ LBD, and thus, secure a position in the bioactive cavity in a similar fashion as does rosiglitazone and 15 d-PGJ₂. By a luciferase reporter assay on rat liver Ac2F cells, the synthesized compounds were evaluated for PPAR-γ transcriptional activity. The differential PPAR-γ transcriptional activities of the geometric and enantiomeric isomers of the selected analog were also evaluated; based on our results, the enantiopure compound (+)-(R,E)-6a1 was suggested as a potential PPAR-γ ligand.

PPAR-γ agonist rosiglitazone ameliorates peritoneal deterioration in peritoneal dialysis rats with LPS-induced peritonitis through up-regulation of AQP-1 and ZO-1

Peritonitis is still a major cause of the death in peritoneal dialysis (PD) patients despite the significant decline of the peritonitis rates in recent years. The present study is designed to evaluate the therapeutic potential of peroxisome proliferator-activated receptor-γ agonist, rosiglitazone, on the structure and function of the peritoneum in a PD rat accompanied with peritonitis induced by lipopolysaccharide (LPS). Our data showed that the peritoneal membrane in the LPS-only group showed increased peritoneal thickness, vessel density, and hypercellularity compared with the PD-only group. Rosiglitazone administration significantly inhibited increase of the three indicators in PD rats with LPS treatment. In line with this, rosiglitazone improved function of the peritoneum in LPS-induced PD rats receiving rosiglitazone, which was reflected by decreased D/P urea and D/P albumin. Mechanistically, rosiglitazone-mediated improvements in the damaged structure and function of the peritoneum in PD rats with LPS treatment were associated with reduced inflammation and preserving mesothelial cell monolayer resulted from up-regulation of AQP-1 and ZO-1. Our findings thus suggest that peroxisome proliferator-activated receptor γ (PPAR-γ) activation might be a reasonable strategy to prevent and ameliorate peritoneal deterioration in PD patients, especially with peritonitis.

In vitro and in silico analyses of Vicia faba L. on Peroxisome proliferator-activated receptor gamma

The agonists of peroxisome proliferator-activated receptor gamma (PPARγ) from natural victual products were used as antidiabetic agents. Faba bean (Vicia faba L.) is a consequential legume that was known to possess potential antidiabetic activity, whose mechanism of action was unknown. The current study was focused to ascertain gene expression of the nuclear receptor PPARγ by Faba bean pod extract in rat cell lines (RINm5F).The real-time polymerase chain reaction analysis demonstrated that Faba bean pod extract in concentrations of 160 µg/mL have shown 4.97-fold stimulation compared with control. The cells treated with 320 µg/mL has shown 5.89-fold upregulation, respectively. Furthermore, in silico docking analysis was carried out against PPARγ, using the bioactive compounds identified from Faba bean pod extracts, which were known reported compounds from the literature. The results suggest that gene expression of PPARγ was inhibited by the constituents in Faba bean. In silico analysis prognosticates, butein has a high binding energy (-8.6 kcal/mol) with an atomic contact energy of -214.10, followed by Apigenin and Quercetin against PPARγ. Similarly, the percentage of interaction was high for butein, followed by Apigenin and Quercetin than other compounds comparatively. Hence, the results conclude inhibition of PPARγ by the bioactive compounds from Faba bean, which may provide insights into developing future therapeutic molecules for diabetes mellitus.

A Novel Topical PPARγ Agonist Induces PPARγ Activity in Ulcerative Colitis Mucosa and Prevents and Reverses Inflammation in Induced Colitis Models

BACKGROUND

Peroxisome proliferator-activated receptor-gamma (PPARγ) exerts anti-inflammatory effects and is therefore a potential target in ulcerative colitis (UC). A novel PPARγ agonist (AS002) developed for local action was evaluated ex vivo in biopsies from UC patients and in vivo in mice with low-grade dextran sodium sulfate (DSS)- and trinitrobenzene sulfonic acid (TNBS)-induced colitis.

METHODS

Colonic biopsies from UC patients (n = 18) and healthy controls (n = 6) were incubated with AS002 or rosiglitazone (positive control) to measure mRNA expression of the PPARγ-responsive gene ADIPOPHILIN and protein levels of UC-related cytokines (enzyme-linked immunosorbent assay). AS002 absorption was determined in the colonic mucosa of UC patients. DSS-colitis mice received PPARγ agonists or vehicle daily by intrarectal administration starting 2 days before induction of colitis (preventive) or from days 3 to 8 (curative). Myeloperoxidase (MPO) and cytokine levels in colonic mucosa were determined. In addition, AS002 effects were studied in TNBS colitis.

RESULTS

AS002 displayed an absorption pattern of a lipophilic drug totally metabolized in the mucosa. AS002 and rosiglitazone increased ADIPOPHILIN mRNA expression (3-fold) and decreased TNF-α, IL-1β, and IL-13 levels in human UC biopsies. In DSS, in both preventive and curative treatment and in TNBS colitis, AS002 protected against macroscopic and histological damage and lowered MPO and TNF-α, IL-1β, and IL-13 levels.

CONCLUSIONS

AS002 triggers anti-inflammatory PPARγ activity in the human colonic mucosa of UC patients and prevents and reverses colitis in mice. Our data suggest that AS002 has potential for topical maintenance treatment of UC, which warrants further studies in vivo in patients.

Selenium and Selenoproteins in Gut Inflammation-A Review

Inflammatory bowel disease (IBD), characterized by severe flares and remissions, is a debilitating condition. While the etiology is unknown, many immune cells, such as macrophages, T cells and innate lymphoid cells, are implicated in the pathogenesis of the disease. Previous studies have shown the ability of micronutrient selenium (Se) and selenoproteins to impact inflammatory signaling pathways implicated in the pathogenesis of the disease. In particular, two transcription factors, nuclear factor-κB (NF-κB), and peroxisome proliferator activated receptor (PPAR)γ, which are involved in the activation of immune cells, and are also implicated in various stages of inflammation and resolution, respectively, are impacted by Se status. Available therapies for IBD produce detrimental side effects, resulting in the need for alternative therapies. Here, we review the current understanding of the role of NF-κB and PPARγ in the activation of immune cells during IBD, and how Se and selenoproteins modulate effective resolution of inflammation to be considered as a promising alternative to treat IBD.

Oral administration of Lentinus edodes β-glucans ameliorates DSS-induced ulcerative colitis in mice via MAPK-Elk-1 and MAPK-PPARγ pathways

To evaluate the anti-inflammatory effect of β-glucans from Lentinus edodes, and its molecular mechanism, the dextran sulfate sodium salt (DSS) induced colitis model of mice and the LPS-stimulated RAW264.7 cell inflammation model were used in this study. 40 ICR male mice were randomly divided into 4 groups: Control, DSS (DSS treated only), DSS + low-βGs (500 mg kg^-1 d^-1) and DSS + high-βGs (1000 mg kg^-1 d^-1). The body weight of the mice with Lentinus edodes β-glucan supplementation increased significantly compared to the DSS group and the disease activity index (DAI) was improved in both βG-treated groups. Compared with the DSS group, histopathological analysis showed that the infiltration of inflammatory cells of both βG-treated groups decreased significantly in colonic tissues. Furthermore, oral administration of β-glucans decreases the concentration of malondialdehyde (MDA) and myeloperoxidase (MPO) and inhibits the expression of iNOS and several inflammatory factors: TNF-α, IL-1β and IL-6 as well as nitric oxide (NO) of the colonic tissues. The mitogen-activated protein kinase (MAPK) pathway is closely related to the expression of pro-inflammatory factors. In the DSS-induced colitis model and the LPS-stimulated RAW264.7 cell model, βGs inhibited the expression of pro-inflammatory factors and blocked the phosphorylation of JNK/ERK1/2 and p38; βGs also suppress the phosphorylation of Elk-1 at Ser84 and the phosphorylation of PPARγ at Ser112. Altogether, these results suggest that Lentinus edodes βGs could inhibit the DSS-induced ulcerative colitis and decrease inflammatory factor expressions. The molecular mechanism may be involved in suppressing MAPK signaling and inactivation of Elk-1 and activation of PPARγ.

Microalgae-derived oxylipins decrease inflammatory mediators by regulating the subcellular location of NFκB and PPAR-γ

Oxylipins (OXLs) are bioactive molecules generated by the oxidation of fatty acids that promote the resolution of acute inflammation and prevent chronic inflammatory processes through molecular mechanisms that are not well known. We have previously reported the anti-inflammatory activity of microalgae-derived OXLs and OXL-containing biomass in two inflammatory bowel disease (IBD) models: 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced acute colitis and TNBS-induced recurrent colitis. In this study, we examined the in vitro anti-inflammatory mechanism of action of the most abundant OXLs isolated from Chlamydomonas debaryana (13S-HOTE and 13S-HODE) and Nannochloropsis gaditana (15S-HEPE). These OXLs decreased IL-1β and IL-6 pro-inflammatory cytokines production as well as iNOS and COX-2 expression levels in THP-1 macrophages. In addition, OXLs decreased IL-8 production in HT-29 colon cells, the major chemokine produced by these cells. The interaction of OXLs with NFκB and PPAR-γ signaling pathways was studied by confocal microscopy. In THP-1 macrophages and HT-29 colon cells, stimulated by LPS and TNFα respectively, a pre-treatment with 13S-HOTE, 13S-HODE and 15S-HEPE (100μM) resulted in a lower nuclear presence of NFκB in both cell lines. The study of the subcellular localization of PPAR-γ showed that the treatment of THP-1 and HT-29 cells with these OXLs caused the migration of PPAR-γ into the nucleus. Colocalization analysis of both transcription factors in LPS-stimulated THP-1 macrophages showed that the pre-treatment with 13S-HOTE, 13S-HODE or 15S-HEPE lowered nuclear colocalization similar to control value, and increased cytosolic localization above control level. These results indicate that these OXLs could act as agonist of PPAR-γ and consequently inhibit NFκB signaling pathway activation, thus lowering the production of inflammatory markers, highlighting the therapeutic potential of these OXLs in inflammatory diseases such as IBD.

Esculentoside A inhibits LPS-induced acute kidney injury by activating PPAR-γ

Acute kidney injury (AKI) is a major clinical problem associated with high morbidity and mortality. Esculentoside A (EsA), a kind of saponin isolated from the root of the Chinese herb Phytolaca esculenta, has been reported to have anti-inflammatory effect. In this study, we aimed to investigate the protective effects of EsA on LPS-induced AKI in mice. The protective effects of EsA was evaluated by detecting kidney histological change, blood urea nitrogen (BUN) and creatinine levels, and inflammatory cytokines production. The results showed that EsA significantly attenuated LPS-induced kidney histological change, as well as BUN and creatinine levels. EsA also inhibited LPS-induced TNF-α, IL-1β, and IL-6 production. LPS-induced NF-κB activation was significantly suppressed by treatment of EsA. In addition, EsA up-regulated the expression of PPAR-γ in a dose-dependent manner. In conclusion, EsA protected mice effectively from LPS-induced AKI by PPAR-γ, which subsequently inhibited LPS-induced inflammatory response.

Anti-inflammatory effects of Dioscorea alata L. anthocyanins in a TNBS-induced colitis model

The purple yam, Dioscorea alata L., is an important source of starch, vitamins and polyphenols. Five different pigments from the purple tubers of this plant were separated by high-performance liquid chromatography-mass spectrometry, and the anthocyanin fraction (DACN) was collected. The anti-inflammatory effects of DACNs were investigated at different concentrations and compared with the standard colitis treatment, 5-aminosalicylic acid, in a trinitrobenzenesulfonic acid (TNBS)-induced colitis mouse model. Macro- and microscopic parameters including body weight change, disease activity index (DAI) and intestinal histology were used for the determination of the anti-inflammatory effects of DACNs. The gene expression levels of tight junction-related proteins in the intestine, myeloperoxidase activity, inducible nitric oxide synthase activity in colonic tissues and pro-inflammatory cytokine production in serum were also measured to elucidate the mechanism of DACN action. Eighty micrograms of DACNs per kilogram of body weight produced potent anti-inflammatory effects in the mouse model of inflammatory bowel disease (IBD), as shown by the DAI (2.78 ± 0.38 vs. 0.44 ± 0.51). Therefore, DACNs may be applied as a potential food supplement in IBD therapy.

The In Vitro and In Vivo Anti-Inflammatory Effects of a Phthalimide PPAR-γ Agonist

Previously, the authors found that 4-hydroxy-2-(4-hydroxyphenethyl) isoindoline-1,3-dione (PD1) (a phthalimide analogue) bound to and activated peroxisome proliferator-activated receptor-γ (PPAR-γ). Since PPAR-γ suppresses inflammatory responses, the present study was undertaken to investigate the anti-inflammatory effects of PD1. In lipopolysaccharide (LPS)-stimulated murine RAW264.7 macrophages, PD1 suppressed the inductions of pro-inflammatory factors, including inducible nitric oxide synthase (iNOS), nitric oxide (NO), cyclooxygenase 2 (COX-2), tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). Concomitantly, PD1 enhanced the expressions of anti-inflammatory factors, such as arginase-1 and interleukin-10 (IL-10), and suppressed LPS-evoked nuclear factor kappa B (NF-κB) p65 subunit phosphorylation in macrophages. In addition, PPAR-γ activated by PD1 was intensively translocated to the nucleus. These observations suggest that the anti-inflammatory mechanism of PD1 involves inhibition of the NF-κB pathway. In a subsequent in vivo animal experiment conducted using a carrageenan-induced acute inflammatory rat paw edema model, intraperitoneal injection of PD1 significantly reduced paw swelling. Histological analysis of rat paw tissue sections revealed less infiltration of immune cells in PD1-pretreated animals. These findings suggest that PD1 be viewed as a lead compound for the development of novel anti-inflammatory therapeutics.

Anti-inflammatory effects of an oxylipin-containing lyophilised biomass from a microalga in a murine recurrent colitis model

Diet and nutritional factors have emerged as possible interventions for inflammatory bowel diseases (IBD), which are characterised by chronic uncontrolled inflammation of the intestinal mucosa. Microalgal species are a promising source of n-3 PUFA and derived oxylipins, which are lipid mediators with a key role in the resolution of inflammation. The aim of the present study was to investigate the effects of an oxylipin-containing lyophilised biomass from Chlamydomonas debaryana on a recurrent 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis mice model. Moderate chronic inflammation of the colon was induced in BALB/c mice by weekly intracolonic instillations of low dose of TNBS. Administration of the lyophilised microalgal biomass started 2 weeks before colitis induction and was continued throughout colitis development. Mice were killed 48 h after the last TNBS challenge. Oral administration of the microalgal biomass reduced TNBS-induced intestinal inflammation, evidenced by an inhibition of body weight loss, an improvement in colon morphology and a decrease in pro-inflammatory cytokines TNF-α, IL-1β, IL-6 and IL-17. This product also down-regulated colonic expressions of inducible nitric oxide, cyclo-oxygenase 2 and NF-κB, as well as increased PPAR-γ. In addition, lyophilised microalgal biomass up-regulated the expressions of the antioxidant transcription factor nuclear factor E2-related factor 2 and the target gene heme oxygenase 1. This study describes for the first time the prophylactic effects of an oxylipin-containing lyophilised microalgae biomass from C. debaryana in the acute phase of a recurrent TNBS-induced colitis model in mice. These findings suggest the potential use of this microalga, or derived oxylipins, as a nutraceutical in the treatment of IBD.

PPAR-γ agonist pioglitazone regulates dendritic cells immunogenicity mediated by DC-SIGN via the MAPK and NF-κB pathways

Dendritic cell-specific ICAM-3 grabbing non-integrin (DC-SIGN) is a dendritic cell-specific lectin which participates in dendritic cell (DC) trafficking, antigen uptake and DC-T cell interactions at the initiation of immune responses. This study investigated whether peroxisome proliferator-activated receptor-gamma (PPAR-γ) activation in human DCs regulates the immunogenicity of DCs mediated by DC-SIGN and exploited the possible molecular mechanisms, especially focused on the signaling pathways of mitogen-activated protein kinases (MAPK) and nuclear factor-κB (NF-κB). Here, we show that the PPAR-γ agonist pioglitazone decreased DC adhesion and transmigration, and DC stimulation of T cell proliferation mediated by DC-SIGN dependent on activation of PPAR-γ, although it increased DC endocytosis independent of PPAR-γ activation. Furthermore, PPAR-γ activation by pioglitazone in DCs down-regulated the expression of DC-SIGN, which was mediated by modulating the balance of the signaling pathways of extracellular signal-regulated kinase, c-Jun N-terminal kinase and NF-κB, but not p38 MAPK. Therefore, we conclude that PPAR-γ activation in human DCs regulates the immunogenicity of DCs mediated by DC-SIGN via the pathways of MAPK and NF-κB. These findings may support the important role of these mediators in the regulation of DC-mediated inflammatory and immunologic processes.

15d-PGJ2-Loaded Solid Lipid Nanoparticles: Physicochemical Characterization and Evaluation of Pharmacological Effects on Inflammation

15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2), a peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist, has physiological properties including pronounced anti-inflammatory activity, though it binds strongly to serum albumin. The use of solid lipid nanoparticles (SLN) can improve therapeutic properties increasing drug efficiency and availability. 15d-PGJ2-SLN was therefore developed and investigated in terms of its immunomodulatory potential. 15d-PGJ2-SLN and unloaded SLN were physicochemically characterized and experiments in vivo were performed. Animals were pretreated with 15d-PGJ2-SLN at concentrations of 3, 10 or 30 μg·kg-1 before inflammatory stimulus with carrageenan (Cg), lipopolysaccharide (LPS) or mBSA (immune response). Interleukins (IL-1β, IL-10 and IL-17) levels were also evaluated in exudates. The 15d-PGJ2-SLN system showed good colloidal parameters and encapsulation efficiency of 96%. The results showed that the formulation was stable for up to 120 days with low hemolytic effects. The 15d-PGJ2-SLN formulation was able to reduce neutrophil migration in three inflammation models tested using low concentrations of 15d-PGJ2. Additionally, 15d-PGJ2-SLN increased IL-10 levels and reduced IL-1β as well as IL-17 in peritoneal fluid. The new 15d-PGJ2-SLN formulation highlights perspectives of a potent anti-inflammatory system using low concentrations of 15d-PGJ2.

The molecular mechanisms of action of PPAR-γ agonists in the treatment of corneal alkali burns (Review)

Corneal alkali burns (CAB) are characterized by injury-induced inflammation, fibrosis and neovascularization (NV), and may lead to blindness. This review evaluates the current knowledge of the molecular mechanisms responsible for CAB. The processes of cytokine production, chemotaxis, inflammatory responses, immune response, cell signal transduction, matrix metalloproteinase production and vascular factors in CAB are discussed. Previous evidence indicates that peroxisome proliferator-activated receptor γ (PPAR-γ) agonists suppress immune responses, inflammation, corneal fibrosis and NV. This review also discusses the role of PPAR-γ as an anti-inflammatory, anti-fibrotic and anti-angiogenic agent in the treatment of CAB, as well as the potential role of PPAR-γ in the pathological process of CAB. There have been numerous studies evaluating the clinical profiles of CAB, and the aim of this systematic review was to summarize the evidence regarding the treatment of CAB with PPAR-γ agonists.

Oroxyloside prevents dextran sulfate sodium-induced experimental colitis in mice by inhibiting NF-κB pathway through PPARγ activation

Oroxyloside, as a metabolite of oroxylin A, may harbor various beneficial bioactivities which have rarely been reported in the previous studies. Here we established the dextran sulfate sodium (DSS)-induced experimental colitis and evaluated the anti-inflammatory effect of oroxyloside in vivo. As a result, oroxyloside attenuated DSS-induced body weight loss, colon length shortening and colonic pathological damage. Furthermore, oroxyloside inhibited inflammatory cell infiltration and decreased myeloperoxidase (MPO) and inducible nitric oxide synthase (iNOS) activities as well. The production of pro-inflammatory cytokines in serum and colon was also significantly reduced by oroxyloside. We unraveled the underlying mechanisms that oroxyloside inhibited NF-κB pathway by activating Peroxisome Proliferator-Activated Receptor γ (PPARγ) to attenuate DSS-induced colitis. Moreover, we investigated the anti-inflammatory effect and mechanisms of oroxyloside in the mouse macrophage cell line RAW264.7 and bone marrow derived macrophages (BMDM). Oroxyloside decreased several LPS-induced inflammatory cytokines, including IL-1β, IL-6 and TNF-α in RAW264.7 and BMDM. We also found that oroxyloside inhibited LPS-induced activation of NF-κB signaling pathway via activating PPARγ in RAW 264.7 and BMDM. Docking study showed that oroxyloside could bind with PPARγ. GW9662, the inhibitor of PPARγ, and PPARγ siRNA transfection blocked the effect of oroxyloside on PPARγ activation. Our study suggested that oroxyloside prevented DSS-induced colitis by inhibiting NF-κB pathway through PPARγ activation. Therefore, oroxyloside may be a promising and effective agent for inflammatory bowel disease (IBD).