The PPARgamma agonist rosiglitazone impairs colonic inflammation in mice with experimental colitis

Gut taste receptor type 1 member 3 is an intrinsic regulator of Western diet-induced intestinal inflammation

BACKGROUND

Long-term intake of a Western diet (WD), characterized by a high-fat content and sugary drinks, is hypothesized to contribute to the development of inflammatory bowel disease (IBD). Despite the identified clinical association, the molecular mechanisms by which dietary changes contribute to IBD development remain unknown. Therefore, we examined the influence of long-term intake of a WD on intestinal inflammation and the mechanisms by which WD intake affects IBD development.

METHODS

Mice fed normal diet or WD for 10 weeks, and bowel inflammation was evaluated through pathohistological and infiltrated inflammatory cell assessments. To understand the role of intestinal taste receptor type 1 member 3 (TAS1R3) in WD-induced intestinal inflammation, cultured enteroendocrine cells harboring TAS1R3, subjected to RNA interference or antagonist treatment, and Tas1r3-deficient mice were used. RNA-sequencing, flow cytometry, 16S metagenomic sequencing, and bioinformatics analyses were performed to examine the involved mechanisms. To demonstrate their clinical relevance, intestinal biopsies from patients with IBD and mice with dextran sulfate sodium-induced colitis were analyzed.

RESULTS

Our study revealed for the first time that intestinal TAS1R3 is a critical mediator of WD-induced intestinal inflammation. WD-fed mice showed marked TAS1R3 overexpression with hallmarks of serious bowel inflammation. Conversely, mice lacking TAS1R3 failed to exhibit inflammatory responses to WD. Mechanistically, intestinal transcriptome analysis revealed that Tas1r3 deficiency suppressed mTOR signaling, significantly increasing the expression of PPARγ (a major mucosal defense enhancer) and upregulating the expression of PPARγ target-gene (tight junction protein and antimicrobial peptide). The gut microbiota of Tas1r3-deficient mice showed expansion of butyrate-producing Clostridia. Moreover, an increased expression of host PPARγ-signaling pathway proteins was positively correlated with butyrate-producing microbes, suggesting that intestinal TAS1R3 regulates the relationship between host metabolism and gut microflora in response to dietary factors. In cultured intestinal cells, regulation of the TAS1R3-mTOR-PPARγ axis was critical for triggering an inflammatory response via proinflammatory cytokine production and secretion. Abnormal regulation of the axis was observed in patients with IBD.

CONCLUSIONS

Our findings suggest that the TAS1R3-mTOR-PPARγ axis in the gut links Western diet consumption with intestinal inflammation and is a potential therapeutic target for IBD.

Cupriavidus necator-Produced Polyhydroxybutyrate/Eudragit FS Hybrid Nanoparticles Mitigates Ulcerative Colitis via Colon-Targeted Delivery of Cyclosporine A

Polyhydroxybutyrate (PHB) has emerged as a novel material for replacing various plastics used in the medical field. However, its application as a drug-delivery carrier for colitis-targeted delivery has not been explored. In this study, we used biosynthesized PHB combined with Eudragit FS (EFS) and cyclosporine A (CSA) to develop pH-responsive controlled CSA-releasing nanoparticles (CSA-PENPs) for colitis-targeted drug delivery and demonstrated its enhanced therapeutic efficacy in a dextran sulfate sodium (DSS)-induced murine colitis model. PHB was successfully biosynthesized in the bacterium Cupriavidus necator, as demonstrated by ¹H-NMR and FT-IR analyses. CSA-PENPs were fabricated via the oil-in-water emulsion solvent evaporation method. Owing to the potent pH-responsive and sustained drug release properties provided by PHB and EFS, CSA-PENPs could deliver a sufficient amount of CSA to inflamed tissues in the distal colon; in contrast, CSA-loaded EFS nanoparticles displayed premature burst release before reaching the target site. Due to enhanced CSA delivery to colitis tissues, CSA-PENPs exhibited potent anti-inflammatory effects in the DSS-induced murine colitis model. Overall, CSA-PENPs could be a promising drug-delivery system for treating ulcerative colitis.

On-demand reconstitutable hyaluronic acid-doped azathioprine microcrystals effectively ameliorate ulcerative colitis via selective accumulation in inflamed tissues

Although CD44-targeted delivery of pure drug microcrystals of azathioprine (AZA) could be a desirable approach to treat ulcerative colitis (UC), premature drug release and systemic absorption before reaching the colitis region remain a major obstacle. In this study, to overcome these limitations, we developed on-demand reconstitutable HA-doped AZA microcrystals (EFS/HA-AZAs) via incorporating hyaluronic acid (HA)-doped AZA microcrystals (HA-AZAs) into a Eudragit FS (EFS) microcomposite. Since EFS acts as a protective layer, the premature release of AZA in the simulated conditions of the stomach and small intestine was substantially reduced, while HA-AZAs were successfully reconstituted from the EFS/HA-AZAs in the colonic environment, resulting from the pH-triggered dissolution of EFS. After complete reconstitution of HA-AZAs in the colon, HA-AZAs selectively accumulated in the inflamed region via the HA-CD44 interaction. Owing to successful colitis-targeted delivery, EFS/HA-AZAs showed potent anti-inflammatory effects in a dextran sulfate sodium-induced murine colitis model within 7 days without systemic toxicity. These results suggest that EFS/HA-AZAs could be a promising drug delivery system for UC treatment.

(-)-α-Bisabolol Alleviates Atopic Dermatitis by Inhibiting MAPK and NF-κB Signaling in Mast Cell

(-)-α-Bisabolol (BIS) is a sesquiterpene alcohol derived mostly from Matricaria recutita L., which is a traditional herb and exhibits multiple biologic activities. BIS has been reported for treatment of skin disorders, but the effect of BIS on anti-atopic dermatitis (AD) remains unclear. Therefore, we investigated the effects of BIS on 2,4-dinitrochlorobenzene (DNCB)-induced AD in BALB/c mice and the underlying mechanism in Bone Marrow-Derived Mast Cells (BMMCs). Topical BIS treatment reduced AD-like symptoms and the release of interleukin (IL)-4 without immunoglobulin (Ig)-E production in DNCB-induced BALB/c mice. Histopathological examination revealed that BIS reduced epidermal thickness and inhibited mast cells in the AD-like lesions skin. Oral administration of BIS effectively and dose-dependently suppressed mast-cell-mediated passive cutaneous anaphylaxis. In IgE-mediated BMMCs, the levels of β-hexosaminidase (β-hex), histamine, and tumor necrosis factor (TNF)-α were reduced by blocking the activation of nuclear factor-қB (NF-қB) and c-Jun N-terminal kinase (JNK) without P38 mitogen activated protein (P38) and extracellular regulated protein kinases (Erk1/2). Taken together, our experimental results indicated BIS suppresses AD by inhibiting the activation of JNK and NF-κB in mast cells. BIS may be a promising therapeutic agent for atopic dermatitis and other mast-cell-related diseases.

Artificial intelligence-rationalized balanced PPARα/γ dual agonism resets dysregulated macrophage processes in inflammatory bowel disease

A computational platform, Boolean network explorer (BoNE), has recently been developed to infuse AI-enhanced precision into drug discovery; it enables invariant Boolean Implication Networks of disease maps for prioritizing high-value targets. Here we used BoNE to query an Inflammatory Bowel Disease (IBD)-map and prioritize a therapeutic strategy that involves dual agonism of two nuclear receptors, PPARα/γ. Balanced agonism of PPARα/γ was predicted to modulate macrophage processes, ameliorate colitis, 'reset' the gene expression network from disease to health. Predictions were validated using a balanced and potent PPARα/γ-dual-agonist (PAR5359) in Citrobacter rodentium- and DSS-induced murine colitis models. Using inhibitors and agonists, we show that balanced-dual agonism promotes bacterial clearance efficiently than individual agonists, both in vivo and in vitro. PPARα is required and sufficient to induce the pro-inflammatory cytokines and cellular ROS, which are essential for bacterial clearance and immunity, whereas PPARγ-agonism blunts these responses, delays microbial clearance; balanced dual agonism achieved controlled inflammation while protecting the gut barrier and 'reversal' of the transcriptomic network. Furthermore, dual agonism reversed the defective bacterial clearance observed in PBMCs derived from IBD patients. These findings not only deliver a macrophage modulator for use as barrier-protective therapy in IBD, but also highlight the potential of BoNE to rationalize combination therapy.

The Role of PPAR-γ in Allergic Disease

PURPOSE OF REVIEW

The incidence of allergic diseases such as asthma, rhinitis and atopic dermatitis has risen at an alarming rate over the last century. Thus, there is a clear need to understand the critical factors that drive such pathologic immune responses. Peroxisome proliferator-activated receptor-γ (PPAR-γ) is a nuclear receptor that has emerged as an important regulator of multiple cell types involved in the inflammatory response to allergens; from airway epithelial cells to T Helper (TH) cells.

RECENT FINDINGS

Initial studies suggested that agonists of PPAR-γ could be employed to temper allergic inflammation, suppressing pro-inflammatory gene expression programs in epithelial cells. Several lines of work now suggest that PPAR-γ plays an essential in promoting 'type 2' immune responses that are typically associated with allergic disease. PPAR-γ has been found to promote the functions of TH2 cells, type 2 innate lymphoid cells, M2 macrophages and dendritic cells, regulating lipid metabolism and directly inducing effector gene expression. Moreover, preclinical models of allergy in gene-targeted mice have increasingly implicated PPAR-γ in driving allergic inflammation. Herein, we highlight the contrasting roles of PPAR-γ in allergic inflammation and hypothesize that the availability of environmental ligands for PPAR-γ may be at the heart of the rise in allergic diseases worldwide.

pH-Responsive Alginate-Based Microparticles for Colon-Targeted Delivery of Pure Cyclosporine A Crystals to Treat Ulcerative Colitis

Cyclosporine A (CsA) is a potent immunosuppressant for treating ulcerative colitis (UC). However, owing to severe systemic side effects, CsA application in UC therapy remains limited. Herein, a colon-targeted drug delivery system consisting of CsA crystals (CsAc)-loaded, Eudragit S 100 (ES)-coated alginate microparticles (CsAc-EAMPs) was established to minimize systemic side effects and enhance the therapeutic efficacy of CsA. Homogeneously-sized CsAs (3.1 ± 0.9 μm) were prepared by anti-solvent precipitation, followed by the fabrication of 47.1 ± 6.5 μm-sized CsAc-EAMPs via ionic gelation and ES coating. CsAc-EAMPs exhibited a high drug loading capacity (48 ± 5%) and a CsA encapsulation efficacy of 77 ± 9%. The in vitro drug release study revealed that CsA release from CsAc-EAMPs was suppressed under conditions simulating the stomach and small intestine, resulting in minimized systemic absorption and side effects. Following exposure to the simulated colon conditions, along with ES dissolution and disintegration of alginate microparticles, CsA was released from CsAc-EAMPs, exhibiting a sustained-release profile for up to 24 h after administration. Given the effective colonic delivery of CsA molecules, CsAc-EAMPs conferred enhanced anti-inflammatory activity in mouse model of dextran sulfate sodium (DSS)-induced colitis. These findings suggest that CsAc-EAMPs is a promising drug delivery system for treating UC.

The protective effect of PPARγ in sepsis-induced acute lung injury via inhibiting PTEN/β-catenin pathway

The present study aims to reveal the molecular mechanism of peroxisome proliferator-activated receptor γ (PPARγ) on sepsis-induced acute lung injury (ALI). To do that, the rat injury model was established using cecal ligation and perforation (CLP) method, followed by different treatments, and the rats were divided into Sham group, CLP group, CLP + rosiglitazone (PPARγ agonist) group, CLP + GW9662 (PPARγ inhibitor) group, CLP + bpV (phosphatase and tensin homolog (PTEN) inhibitor) group, CLP + GW9662 + bpV group. Compared with Sham group, the mRNA and protein expression levels of PPARγ were down-regulated, the inflammation levels were elevated, and the apoptosis was increased in CLP group. After treatment with rosiglitazone, the protein expression level of PPARγ was significantly up-regulated, the phosphorylation level of PTEN/β-catenin pathway was decreased, the PTEN/β-catenin pathway was inhibited, the lung injury, inflammation and apoptosis were reduced. The opposite effect was observed after treatment with GW9662. Besides, bpV inhibited PTEN/β-catenin pathway, and relieved the lung tissue injury. The overexpression of PPARγ reduced inflammatory response and inhibited apoptosis in sepsis-induced ALI. Furthermore, PPARγ relieved the sepsis-induced ALI by inhibiting the PTEN/β-catenin pathway.

Colitis-targeted hybrid nanoparticles-in-microparticles system for the treatment of ulcerative colitis

Nanoparticle (NP)-based drug delivery systems accumulate in the disrupted epithelium of inflamed colon tissue in ulcerative colitis. However, premature early drug release and uptake or degradation of NPs during their passage through the harsh gastric or intestinal environment compromise their therapeutic outcomes. This study aimed to develop an advanced colitis-targeted hybrid nanoparticles-in-microparticles (NPsinMPs) drug delivery system to overcome the aforementioned challenges. First, sustained drug releasing poly(lactic-co-glycolic acid) NPs were generated and further encapsulated in pH-sensitive Eudragit FS30D MPs to ensure complete drug protection in a gastric-like pH and for selective delivery of NPs to the colon. SEM and confocal microscopy for the NPsinMPs revealed successful NP encapsulation. NPsinMPs prevented drug release in an acidic gastric-like and intestinal-like pH and presented a sustained release thereafter at an ileal and colonic pH, indicating the degradation of the outer pH-sensitive MPs and release of NPs. Furthermore, in vivo imaging of gastrointestinal tract of a colitis mouse orally administered with fluorescent NPsinMPs revealed higher fluorescence intensities selectively in the colon, demonstrating the release of loaded NPs and their concomitant accumulation at the site of colon inflammation. NPsinMPs markedly mitigated experimental colitis in mice indicated by improved histopathological analysis, decreased myeloperoxidase activity, neutrophils and macrophage infiltration, and expression of proinflammatory cytokines in colonic tissues compared with NP-treated mice. The present results show the successful formulation of an NPsinMP-based drug delivery system and provide a platform to improve NP-based colon-targeted drug delivery through improved protection of encapsulated NPs and their payload in the early small intestine.

Amelioration of ulcerative colitis via inflammatory regulation by macrophage-biomimetic nanomedicine

Ulcerative colitis (UC) is featured with relapsing inflammation in the colon, where macrophages are recruited and polarized locally into M1 type to drive further inflammation. Pharmacotherapy of UC has exhibited limited efficacy, mostly due to the poor specificity.

Methods: A macrophage-biomimetic nanomedicine was developed for targeted treatment of UC, which was derived from reactive oxygen species (ROS)-sensitive β-cyclodextrin, loaded with rosiglitazone, and coated with macrophage membrane. The ability of the nanomedicine in regulating macrophage polarization was examined at cellular level, and the macrophage-tropism driven targeted delivery into the inflammatory colon was investigated by ex vivo bio-imaging distribution assay. Furthermore, the nanomedicine's therapeutic efficacy was systemically examined in dextran sulfate sodium (DSS)-induced colitis model in mice.

Results: The nanomedicine effectively polarized macrophages to M2 and protected epithelial cells from oxidative stress in vitro. In addition, macrophage-membrane led the nanomedicine to the inflammatory colon with a high targeting efficiency. In response to the elevated ROS in the inflammatory tissue, the nanomedicine released rosiglitazone specifically and regulated macrophage polarization in vivo. Macrophage membrane also assisted inflammation suppression by sequestering proinflammatory cytokines. Working in such a synergy, the nanomedicine exhibited significant therapeutic effects against UC in mice.

Conclusions: This macrophage-biomimetic nanomedicine leverages the inflammatory tropism and inflammatory cytokine sequestration effects of macrophage membrane for targeted delivery and local inflammation suppression, the ROS-responsiveness of β-cyclodextrin-based matrix for specific payload release, and the macrophage-polarizing effect of rosiglitazone for inflammatory regulation, thereby exhibiting considerable therapeutic efficacy against UC in mice. This study offers important new insights on the design and development of biomimetic nanomaterials for inflammation regulations.

Myotubularin-related protein 7 activates peroxisome proliferator-activated receptor-gamma

Peroxisome proliferator-activated receptor-gamma (PPARγ) is a transcription factor drugable by agonists approved for treatment of type 2 diabetes, but also inhibits carcinogenesis and cell proliferation in vivo. Activating mutations in the Kirsten rat sarcoma viral oncogene homologue (KRAS) gene mitigate these beneficial effects by promoting a negative feedback-loop comprising extracellular signal-regulated kinase 1/2 (ERK1/2) and mitogen-activated kinase kinase 1/2 (MEK1/2)-dependent inactivation of PPARγ. To overcome this inhibitory mechanism, we searched for novel post-translational regulators of PPARγ. Phosphoinositide phosphatase Myotubularin-Related-Protein-7 (MTMR7) was identified as cytosolic interaction partner of PPARγ. Synthetic peptides were designed resembling the regulatory coiled-coil (CC) domain of MTMR7, and their activities studied in human cancer cell lines and C57BL6/J mice. MTMR7 formed a complex with PPARγ and increased its transcriptional activity by inhibiting ERK1/2-dependent phosphorylation of PPARγ. MTMR7-CC peptides mimicked PPARγ-activation in vitro and in vivo due to LXXLL motifs in the CC domain. Molecular dynamics simulations and docking predicted that peptides interact with the steroid receptor coactivator 1 (SRC1)-binding site of PPARγ. Thus, MTMR7 is a positive regulator of PPARγ, and its mimicry by synthetic peptides overcomes inhibitory mechanisms active in cancer cells possibly contributing to the failure of clinical studies targeting PPARγ.

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.

Consumption of a baked corn and bean snack reduced chronic colitis inflammation in CD-1 mice via downregulation of IL-1 receptor, TLR, and TNF-α associated pathways

Ulcerative colitis (UC) is a condition that has been rising in the number of cases around the world. Food products made from natural ingredients such as corn and common bean might serve as alternatives for the treatment of UC. This study aimed to assess the anti-inflammatory effect of the consumption of a baked corn and bean snack (CBS) in an in vivo model of UC using 2% dextran sodium sulfate (DSS) as inductor of colitis. CD-1 mice (45, n = 9/group) were randomly separated into 5 groups, treated for 6-weeks as follows: G1 (basal diet, BD), G2 (2% DSS), G3 (20 g CBS/body weight BW/day + BD), G4 (40 g CBS/BW/day + BD) and G5 (60 g CBS/BW/day + BD). BW, Disease Activity Index (DAI), and feces were collected throughout the treatment. After euthanasia, organs (spleen, liver, and colon) were excised and weighed. Feces were analyzed for β-glucuronidase (β-GLUC) activity and gas-chromatography. The colons were analyzed for histopathology, myeloperoxidase (MPO) activity, and gene analysis. At the end of treatments, among the DSS-induced groups, G3 exhibited the lowest BW losses (11.5%), MPO activity (10.4%) and β-GLUC (8.6%). G4 presented the lowest DAI (0.88), relative spleen weight, and histological inflammation score (p < 0.05). Compared to G2, CBS consumption significantly (p < 0.05) reduced serum TNF-α, IL-10, and MCP-1 levels. The fecal metabolome analysis ranked 9-decenoic acid, decane, and butyric acid as the main contributors of pathways associated with the β-oxidation of fatty acids. G4 showed the highest fecal/cecal contents of short-chain fatty acids among all the DSS-induced groups. For the gene expression, G4 was clustered with G1, showing a differential inhibition of the pro-inflammatory genes Il1r1, Il1a, Tlr4, Tlr2, and Tnfrsf1b. In conclusion, CBS consumption decreased the inflammatory state and reduced the expression of the IL-1 receptor, TLR, and TNF-α-associated pathways in DSS-induced UC in CD-1 mice.

Rosiglitazone prevents acute pancreatitis through inhibiting microRNA-26a expression

The aim of the present study was to investigate the regulatory effect of rosiglitazone on the progression of acute pancreatitis (AP) and pancreas injury, and the underlying mechanism. An AP rat model was established using caerulein and validated by detection of amylase, lipase, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and transforming growth factor-β (TGF-β) serum levels. Pancreatic injury was assessed by pathological examination. The expression levels of microRNA (miR)-26a in AP rats and AR42J cells were analyzed using reverse transcription-quantitative PCR (RT-qPCR). Luciferase reporter gene assay was applied for detecting whether miR-26a bound to the target gene phosphatase and tensin homolog (PTEN). The regulatory effect of rosiglitazone on the PI3K/AKT signaling pathway was analyzed by western blot analysis. Results demonstrated that establishment of an AP model was successful with severe pancreas injury and classic AP phenotypes observed in rats. Increased serum expression of amylase, lipase, TNF-α, IL-6 and TGF-β were observed in AP rats. Rosiglitazone pretreatment prevented AP progression through suppression of miR-26a expression via binding to and degrading PTEN. Western blot analysis demonstrated that rosiglitazone blocked the PI3K/AKT signaling pathway through PTEN. In conclusion, it was determined that rosiglitazone prevented AP by downregulating miR-26a via the PI3K/AKT signaling pathway.

Peroxisome proliferator-activated receptor gamma ligands affect NF-kB and cytokine synthesis in the porcine endometrium-An in vitro study

PROBLEM

Cytokines, mediators of the immune response, are involved in the regulation of female reproductive processes during the estrous cycle and pregnancy. The present study aimed to investigate the effect of selected peroxisome proliferator-activated receptor gamma (PPARγ) ligands on the expression of nuclear factor kappa B (NF-κB) and selected cytokines, such as interleukin (IL)-1β, -4, -6, -8, -10, and the leukemia inhibitory factor, in the porcine endometrium on days 10-12 and 14-16 of the estrous cycle (mid- and late luteal phase, respectively) or pregnancy (maternal recognition of pregnancy and beginning of implantation, respectively).

METHOD OF STUDY

Endometrial slices were incubated in vitro in the presence of PPARγ agonists, 15-deoxy-Δ12, 14-prostaglandin J₂ or rosiglitazone, and PPARγ antagonist T0070907. mRNA and protein levels in tissues were determined by real-time PCR and Western blot.

RESULTS

On days 10-12 of the estrous cycle and days 14-16 of pregnancy, PPARγ ligands enhanced the expression of NF-κB, mRNA cytokines, and/or proteins. During the late luteal phase of the estrous cycle (days 14-16) and maternal recognition of pregnancy (days 10-12), PPARγ ligands inhibited the expression of NF-κB, and they differentially affected the expression of mRNA and proteins of cytokines.

CONCLUSION

Our results indicate that PPARγ is engaged in the endometrial synthesis of NF-κB and selected cytokines in pigs. The influence of PPARγ ligands on the tested components of the immune system varied subject to the physiological status of females, and it could be associated with differences in endometrial receptivity.

MFHAS1 promotes colorectal cancer progress by regulating polarization of tumor-associated macrophages via STAT6 signaling pathway

Malignant fibrous histiocytoma amplified sequence 1 (MFHAS1) is a predicted oncoprotein that demonstrates tumorigenic activity in vivo; however, the mechanisms involved are unknown. Macrophages are divided into the pro-inflammatory M1 and anti-inflammatory/protumoral M2 subtypes. Tumor cells can induce M2 polarization of tumor-associated macrophages (TAMs) to promote metastasis; but the underlying pathways require to be elucidated. In this study, we detected a positive association between MFHAS1 expression in TAMs and human colorectal cancer (CRC) TNM stage. Supernatant of CT26 murine CRC cells induced MFHAS1 expression in RAW264.7 murine macrophages. Additionally, CT26 supernatant induced the M2 marker CD206 and activated the pro-M2 STAT6 and KLF4 signaling in control but not MFHAS1-silenced RAW264.7 macrophages. Moreover, supernatant of control, but not MFHAS1-silenced macrophages promoted CT26 cell proliferation, migration and epithelial-mesenchymal transition. Compared with control macrophages, MFHAS1-silenced macrophages showed significantly reduced protumoral effects in vivo. Together, these results suggested that CRC cells induce M2 polarization of TAMs through MFHAS1 induction and subsequent STAT6 and KLF4 activation to promote CRC progress. Finally, similar to CT26 supernatant stimulation, peroxisome proliferator-activated receptor-γ (PPARγ) activation by rosiglitazone induced M2 polarization of RAW264.7 macrophages through MFHAS1-dependent pathway. Our results highlight the role of MFHAS1 as a regulator of macrophages polarization and CRC progress.

pH-triggered surface charge-reversal nanoparticles alleviate experimental murine colitis via selective accumulation in inflamed colon regions

In this study, we developed pH-triggered surface charge-reversal lipid nanoparticles (LNPs), loaded with budesonide, which could precisely deliver the drug to inflamed colon segments for the treatment of ulcerative colitis. Polyethyleneimine (PEI) was used to render LNPs cationic (PEI-LNPs), and Eudragit® S100 (ES) was coated on PEI-LNPs to obtain pH-triggered charge-reversal LNPs (ES-PEI-LNPs). ES coating avoided a burst drug release under acidic conditions mimicking the stomach and early small intestine environments and showed a sustained release in the colon. The surface charge of ES-PEI-LNPs switched from negative to positive under colonic conditions owing to pH-triggered removal of the ES coating. Bioimaging of the mouse gastrointestinal tract and confocal analysis of colon tissues revealed that ES-PEI-LNPs selectively accumulated in an inflamed colon. Furthermore, ES-PEI-LNPs mitigated experimental colitis in mice. These results suggest that the pH-triggered charge-reversal LNPs could be a promising drug carrier for ulcerative colitis therapy and other colon-targeted treatments.

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.

Adipokines and the role of visceral adipose tissue in inflammatory bowel disease

Recently, adipocytes have been recognized as actively participating in local and systemic immune responses via the secretion of peptides detectable in relevant levels in the systemic circulation, the so-called "adipo(cyto)kines". Multiple studies appearing within the last 10-15 years have focused on the possible impact of adipose tissue depots on inflammatory bowel disease (IBD). Consequently, various hypotheses regarding the role of different adipokines in inflammatory diseases in general and in intestinal inflammatory processes in particular have been developed and have been further refined in recent years. After a focused summary of the data reported concerning the impact of visceral adipose tissue on IBD, such as Crohn's disease and ulcerative colitis, our review focuses on recent developments indicating that adipocytes as part of the innate immune system actively participate in antimicrobial host defenses in the context of intestinal bacterial translocation, which are of utmost importance for the homeostasis of the whole organism. Modulators of adipose tissue function and regulators of adipokine secretion, as well as modifiers of adipocytic pattern recognition molecules, might represent future potential drug targets in IBD.

DrugGenEx-Net: a novel computational platform for systems pharmacology and gene expression-based drug repurposing

Background

The targeting of disease-related proteins is important for drug discovery, and yet target-based discovery has not been fruitful. Contextualizing overall biological processes is critical to formulating successful drug-disease hypotheses. Network pharmacology helps to overcome target-based bottlenecks through systems biology analytics, such as protein-protein interaction (PPI) networks and pathway regulation.

Results

We present a systems polypharmacology platform entitled DrugGenEx-Net (DGE-NET). DGE-NET predicts empirical drug-target (DT) interactions, integrates interaction pairs into a multi-tiered network analysis, and ultimately predicts disease-specific drug polypharmacology through systems-based gene expression analysis. Incorporation of established biological network annotations for protein target-disease, −signaling pathway, −molecular function, and protein-protein interactions enhances predicted DT effects on disease pathophysiology. Over 50 drug-disease and 100 drug-pathway predictions are validated. For example, the predicted systems pharmacology of the cholesterol-lowering agent ezetimibe corroborates its potential carcinogenicity.

When disease-specific gene expression analysis is integrated, DGE-NET prioritizes known therapeutics/experimental drugs as well as their contra-indications. Proof-of-concept is established for immune-related rheumatoid arthritis and inflammatory bowel disease, as well as neuro-degenerative Alzheimer’s and Parkinson’s diseases.

Conclusions

DGE-NET is a novel computational method that predicting drug therapeutic and counter-therapeutic indications by uniquely integrating systems pharmacology with gene expression analysis. DGE-NET correctly predicts various drug-disease indications by linking the biological activity of drugs and diseases at multiple tiers of biological action, and is therefore a useful approach to identifying drug candidates for re-purposing.

Electronic supplementary material

The online version of this article (doi:10.1186/s12859-016-1065-y) contains supplementary material, which is available to authorized users.

Promoter methylation status and expression of PPAR-γ gene are associated with prognosis of acute-on-chronic hepatitis B liver failure

Background

Peroxisome proliferator-activated receptor gamma (PPAR-γ) has been demonstrated to be involved in anti-inflammatory reactions, but its role in acute-on-chronic hepatitis B liver failure (ACHBLF) is unclear. Therefore, DNA methylation patterns and expression level of PPAR-γ gene were detected in peripheral blood mononuclear cells (PBMCs) from 81 patients with ACHBLF, 50 patients with chronic hepatitis B (CHB), and 30 healthy controls, and the possible role of PPAR-γ in ACHBLF was analyzed.

Results

We found that aberrant PPAR-γ promoter methylation was attenuated in ACHBLF patients compared with CHB patients and was responsible for the elevated PPAR-γ expression level, which was negatively correlated with total bilirubin and international normalized ratio. Plasma level of TNF-α and IL-6 in ACHBLF patients were higher than CHB patients and healthy controls and significantly reduced in unmethylated group. ACHBLF patients with PPAR-γ promoter methylation had poorer outcomes than those without. Correspondingly, PPAR-γ messenger RNA (mRNA) level was higher in survivors than non-survivors and gradually increased in survivors with time, while remained low level in non-survivors.

Conclusions

Aberrant promoter methylation decline and PPAR-γ expression rebound occurred in ACHBLF compared with CHB and could improve prognosis of ACHBLF by negatively regulating cytokines.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-015-0149-2) contains supplementary material, which is available to authorized users.

Airway epithelial cell PPARγ modulates cigarette smoke-induced chemokine expression and emphysema susceptibility in mice

Chronic obstructive pulmonary disease (COPD) is a highly prevalent, chronic inflammatory lung disease with limited existing therapeutic options. While modulation of peroxisome proliferator-activating receptor (PPAR)-γ activity can modify inflammatory responses in several models of lung injury, the relevance of the PPARG pathway in COPD pathogenesis has not been previously explored. Mice lacking Pparg specifically in airway epithelial cells displayed increased susceptibility to chronic cigarette smoke (CS)-induced emphysema, with excessive macrophage accumulation associated with increased expression of chemokines, Ccl5, Cxcl10, and Cxcl15. Conversely, treatment of mice with a pharmacological PPARγ activator attenuated Cxcl10 and Cxcl15 expression and macrophage accumulation in response to CS. In vitro, CS increased lung epithelial cell chemokine expression in a PPARγ activation-dependent fashion. The ability of PPARγ to regulate CS-induced chemokine expression in vitro was not specifically associated with peroxisome proliferator response element (PPRE)-mediated transactivation activity but was correlated with PPARγ-mediated transrepression of NF-κB activity. Pharmacological or genetic activation of PPARγ activity abrogated CS-dependent induction of NF-κB activity. Regulation of NF-κB activity involved direct PPARγ-NF-κB interaction and PPARγ-mediated effects on IKK activation, IκBα degradation, and nuclear translocation of p65. Our data indicate that PPARG represents a disease-relevant pathophysiological and pharmacological target in COPD. Its activation state likely contributes to NF-κB-dependent, CS-induced chemokine-mediated regulation of inflammatory cell accumulation.

Modulation of peroxisome proliferator-activated receptor gamma (PPAR γ) by conjugated fatty acid in obesity and inflammatory bowel disease

Conjugated fatty acids including conjugated linoleic acid (CLA) and conjugated linolenic acid (CLNA) have drawn significant attention for their variety of biologically beneficial effects. Evidence suggested that CLA and CLNA could play physiological roles by regulating the expression and activity of PPAR γ. This review summarizes the current understanding of evidence of the role of CLA (cis-9,trans-11 CLA and trans-10,cis-12 CLA) and CLNA (punicic acid and α-eleostearic acid) in modulating the expression or activity of PPAR γ that could in turn be employed as complementary treatment for obesity and inflammatory bowel disease.

Therapeutic activity of an interleukin-4/interleukin-13 dual antagonist on oxazolone-induced colitis in mice

Interleukin-4 (IL-4) and IL-13 are critical drivers of immune activation and inflammation in ulcerative colitis, asthma and other diseases. Because these cytokines may have redundant function, dual targeting holds promise for achieving greater efficacy. We have recently described a bifunctional therapeutic targeting IL-4 and IL-13 developed on a novel protein scaffold, generated by combining specific binding domains in an optimal configuration using appropriate linker regions. In the current study, the bifunctional IL-4/IL-13 antagonist was evaluated in the murine oxazolone-induced colitis model, which produces disease with features of ulcerative colitis. The bifunctional IL-4/IL-13 antagonist reduced body weight loss throughout the 7-day course of the model, and ameliorated the increased colon weight and decreased colon length that accompany disease. Colon tissue gene expression was modulated in accordance with the treatment effect. Concentrations of serum amyloid P were elevated in proportion to disease severity, making it an effective biomarker. Serum concentrations of the bifunctional IL-4/IL-13 antagonist were inversely proportional to disease severity, colon tissue expression of pro-inflammatory genes, and serum amyloid P concentration. Taken together, these results define a panel of biomarkers signifying engagement of the IL-4/IL-13 pathway, confirm the T helper type 2 nature of disease in this model, and demonstrate the effectiveness of dual cytokine blockade.

Cellular metabolism and macrophage functional polarization

Macrophages are a functionally heterogeneous cell population that is mainly shaped by a variety of microenvironmental stimuli. Interferon γ (IFN-γ), interleukin-1β (IL-1β), and lipopolysaccharide (LPS) induce a classical activation of macrophages (M1), whereas IL-4 and IL-13 induce an alternative activation program in macrophages (M2). Reprogramming of intracellular metabolisms is required for the proper polarization and functions of activated macrophages. Similar to the Warburg effect observed in tumor cells, M1 macrophages increase glucose consumption and lactate release and decreased oxygen consumption rate. In comparison, M2 macrophages mainly employ oxidative glucose metabolism pathways. In addition, fatty acids, vitamins, and iron metabolisms are also related to macrophage polarization. However, detailed metabolic pathways involved in macrophages have remained elusive. Understanding the bidirectional interactions between cellular metabolism and macrophage functions in physiological and pathological situations and the regulatory pathways involved may offer novel therapies for macrophage-associated diseases.

Role of tight junctions in signal transduction: an update

Tight junctions (TJs), which are the most apically located of the intercellular junctional complexes, have a barrier function and a fence function. Recent studies show that they also participate in signal transduction mechanisms. TJs are modulated by intracellular signaling pathways including protein kinase C, mitogen-activated protein kinase, and NF-ϰB, to affect the epithelial barrier function in response to diverse stimuli. TJs are also regulated by various cytokines, growth factors, and hormones via signaling pathways. To investigate the regulation of TJ molecules via signaling pathways in human epithelial cells under normal and pathological conditions, we established a novel model of human telomerase reverse transcriptase-transfected human epithelial cells. In this review, we describe the recent progress in our understanding of the role of TJs for signal transduction under normal conditions in upper airway epithelium, pancreatic duct epithelial cells, hepatocytes, and endometrial epithelial cells, and in pathological conditions including cancer and infection.

Current overview of extrinsic and intrinsic factors in etiology and progression of inflammatory bowel diseases

Inflammatory bowel diseases (IBD) are chronic, relapsing disorders affecting gastrointestinal (GI) tract and associated with intestinal mucosa damage and inflammation. The principal therapeutic goals in IBD include control of the intestinal inflammation and treatment of the major symptoms, mainly abdominal pain and diarrhea. Current therapeutic strategies for IBD rely on the use of non-specific anti-inflammatory agents and immunosuppressive drugs (e.g. aminosalicylates, monoclonal antibodies, and antibiotics), which cause severe side effects, and - in a significant number of patients - do not induce long-term benefits. In this review, we summarize the epidemiology and the most important risk factors of IBD, including genetic, immunological and environmental. Our main focus is to discuss pharmacological targets for current and future treatments of IBD.

Decreased PPAR-γ expression in the conjunctiva and increased expression of TNF-α and IL-1β in the conjunctiva and tear fluid of dry eye mice

The aim of this study was to investigate the expression of peroxisome proliferator-activated receptor γ (PPAR-γ), tumor necrosis factor (TNF)-α and interleukin (IL)-1β in the conjunctiva and the association between inflammatory cytokines and PPAR-γ in dry eye mice. Dry eye was induced in 6-week-old female C57 mice. mRNA expression of PPAR-γ, TNF-α and IL-1β were measured. PPAR-γ protein expression in the conjunctiva, and the contents of TNF-α and IL-1β in the conjunctiva and tear-wash fluid were determined. A PPAR-γ agonist, pioglitazone (PIO), was used to treat dry eye mice. Dry eye mice presented with similar manifestations as in humans. The PPAR-γ expression in the conjunctiva of dry eye mice was downregulated, accompanied by increased contents of TNF-α and IL-1β. PIO treatment markedly reduced the contents of TNF-α and IL-1β in tear fluid of dry eye mice. Following PIO treatment, the PPAR-γ expression increased markedly. PIO may activate PPAR-γ to inhibit the expression of the inflammatory cytokines TNF-α and IL-1β in dry eye mice. This suppresses the inflammatory progression, increases the tear fluid production, elevates the tear film stability and reduces the damage to the ocular surface, exerting a therapeutic effect on dry eye.

Heat-killed VSL#3 ameliorates dextran sulfate sodium (DSS)-induced acute experimental colitis in rats

To determine the effects of heat-killed VSL#3 (B. breve, B. longum and B. infantis; L. plantarum, L. bulgaricus, L. casei and L. acidophilus; S. salivarius subsp. thermophilus) therapy in the dextran sulfate sodium (DSS)-induced acute experimental colitis in rats. Acute experimental colitis was induced in rats by 5% DSS and freely drink for seven days. Beginning on Day 8, rats underwent gavage once daily for seven days with heat-killed probiotic VSL#3 (0.6 g/kg/day), colonic damage was evaluated histologically and biochemically seven days after gavage. Expression of inflammatory related mediators (STAT3, P-STAT3) and cytokines (IL-6, IL-23, TGFβ) in colonic tissue were detected. The results revealed that heat-killed and live VSL#3 have identical anti-inflammatory properties by the assessed DAI (disease activity index), colon length, histological tissue and MPO activity. Heat-killed and live VSL#3 results in reduced IL-6, IL-23, TGFβ, STAT3 and P-STAT3 expression in colonic tissue. Heat-killed and live VSL#3 have showed the similar anti-inflammatory activity by inhibiting IL-6/STAT3 pathway in the DSS-induced acute experimental colitis in rats.

Regulation of the mucosal phenotype in dendritic cells by PPARγ: role of tissue microenvironment

Mucosal DCs play a critical role in tissue homeostasis. Several stimuli can induce a mucosal phenotype; however, molecular pathways that regulate development of mucosal DC function are relatively unknown. This study sought to determine whether PPARγ contributes to the development of the "mucosal" phenotype in mouse DCs. Experiments demonstrated that PPARγ activation in BMDCs induced an immunosuppressive phenotype in which BMDCs had reduced expression of MHC class II and costimulatory molecules, increased IL-10 secretion, and reduced the ability to induce CD4 T cell proliferation. Activation of PPARγ enhanced the ability of BMDC to polarize CD4 T cells toward iTregs and to induce T cell expression of the mucosal homing receptor, CCR9. Activation of PPARγ increased the ability of BMDCs to induce T cell-independent IgA production in B cells. BMDCs from PPARγ(ΔDC) mice displayed enhanced expression of costimulatory molecules, enhanced proinflammatory cytokine production, and decreased IL-10 synthesis. Contrary to the inflammatory BMDC phenotype in vitro, PPARγ(ΔDC) mice showed no change in the frequency or phenotype of mDC in the colon. In contrast, mDCs in the lungs were increased significantly in PPARγ(ΔDC) mice. A modest increase in colitis severity was observed in DSS-treated PPARγ(ΔDC) mice compared with control. These results indicate that PPARγ activation induces a mucosal phenotype in mDCs and that loss of PPARγ promotes an inflammatory phenotype. However, the intestinal microenvironment in vivo can maintain the mucosal DC phenotype of via PPARγ-independent mechanisms.

The role of lipid-activated nuclear receptors in shaping macrophage and dendritic cell function: From physiology to pathology

Nuclear receptors are ligand-activated transcription factors linking lipid signaling to the expression of the genome. There is increasing appreciation of the involvement of this receptor network in the metabolic programming of macrophages and dendritic cells (DCs), essential members of the innate immune system. In this review we focus on the role of retinoid X receptor, retinoic acid receptor, peroxisome proliferator-associated receptor γ, liver X receptor, and vitamin D receptor in shaping the immune and metabolic functions of macrophages and DCs. We also provide an overview of the contribution of macrophage- and DC-expressed nuclear receptors to various immunopathologic conditions, such as rheumatoid arthritis, inflammatory bowel disease, systemic lupus erythematosus, asthma, and some others. We suggest that systematic analyses of the roles of these receptors and their activating lipid ligands in immunopathologies combined with complementary and focused translational and clinical research will be crucial for the development of new therapies using the many molecules available to target nuclear receptors.

Novel regulatory action of ribosomal inactivation on epithelial Nod2-linked proinflammatory signals in two convergent ATF3-associated pathways

In response to excessive nucleotide-binding oligomerization domain-containing protein 2 (Nod2) stimulation caused by mucosal bacterial components, gut epithelia need to activate regulatory machinery to maintain epithelial homeostasis. Activating transcription factor 3 (ATF3) is a representative regulator in the negative feedback loop that modulates TLR-associated inflammatory responses. In the current study, the regulatory effects of ribosomal stress-induced ATF3 on Nod2-stimulated proinflammatory signals were assessed. Ribosomal inactivation caused persistent ATF3 expression that in turn suppressed proinflammatory chemokine production facilitated by Nod2. Decreased chemokine production was due to attenuation of Nod2-activated NF-κB and early growth response protein 1 (EGR-1) signals by ATF3. However, the underlying molecular mechanisms involve two convergent regulatory pathways. Although ATF3 induced by ribosomal inactivation regulated Nod2-induced EGR-1 expression epigenetically through the recruitment of histone deacetylase 1, NF-κB regulation was associated with posttranscriptional regulation by ATF3 rather than epigenetic modification. ATF3 induced by ribosomal inactivation led to the destabilization of p65 mRNA caused by nuclear entrapment of transcript-stabilizing human Ag R protein via direct interaction with ATF3. These findings demonstrate that ribosomal stress-induced ATF3 is a critical regulator in the convergent pathways between EGR-1 and NF-κB, which contributes to the suppression of Nod2-activated proinflammatory gene expression.

PPARγ in Inflammatory Bowel Disease

Peroxisome proliferator-activated receptor gamma (PPARγ) is member of a family of nuclear receptors that interacts with nuclear proteins acting as coactivators and corepressors. The colon is a major tissue which expresses PPARγ in epithelial cells and, to a lesser degree, in macrophages and lymphocytes and plays a role in the regulation of intestinal inflammation. Indeed, both natural and synthetic PPARγ ligands have beneficial effects in different models of experimental colitis, with possible implication in the therapy of inflammatory bowel disease (IBD). This paper will specifically focus on potential role of PPARγ in the predisposition and physiopathology of IBD and will analyze its possible role in medical therapy.

Smooth muscle-specific overexpression of PGC-1α protects mice from acute colitis

AIM: To investigate the effect of smooth muscle-specific overexpression of peroxidase proliferator-activated receptor gamma coactivator-1α (PGC-1α) on dextran sulfate sodium (DSS)-induced acute colitis in mice.

METHODS: Two-month-old male mice were divided into four groups according to genotype (non-Tg/Tg) and treatment (H₂O/DSS), 10-13 mice for each group. Mice were administered with 3% DSS in drinking water for 7 days (+DSS) to induce inflammatory bowel disease (IBD). Control groups were given normal drinking water (+H₂O). At the end of the study, the symptoms and pathological changes were evaluated using disease activity index (DAI) and histopathological score (HPS) of acute colitis, respectively. The mRNA levels of inflammatory cytokines in the colon were determined.

RESULTS: Compared to control groups, DSS-treated groups had significantly decreased body weight (both P < 0.01), increased DAI (both P < 0.01) and HPS (9.6 ± 1.2 vs 1.2 ± 0.4; 5.0 ± 0.8 vs 1.2 ± 0.6, in non-Tg and Tg groups, respectively, both P < 0.01), and significantly shorter colon (5.0 cm ± 0.3 cm vs 7.8 cm ± 0.2 cm; 4.9 cm ± 0.1 cm vs 8.0 cm ± 0.3 cm, in non-Tg and Tg groups, respectively, both P < 0.01). Compared to the DSS-treated non-Tg group, the treated Tg group had significantly decreased DAI (P < 0.01), HPS (5.0 ± 0.8 vs 9.6 ± 1.2, P < 0.01) and tumor necrosis factor α (TNFα) mRNA level (0.24 ± 0.07 vs 0.45 ± 0.10, P < 0.05), and increased peroxidase proliferator-activated receptor γ (PPARγ) mRNA level (0.98 ± 0.15 vs 0.41 ± 0.07, P < 0.05).

CONCLUSION: Smooth muscle-specific overexpression of PGC-1α protects against DSS-induced acute colitis by reducing the expression of inflammatory factor TNFα, which might result from the activation of PPARγ.

Adiponectin and plant-derived mammalian adiponectin homolog exert a protective effect in murine colitis

BACKGROUND

Hypoadiponectinemia has been associated with states of chronic inflammation in humans. Mesenteric fat hypertrophy and low adiponectin have been described in patients with Crohn's disease. We investigated whether adiponectin and the plant-derived homolog, osmotin, are beneficial in a murine model of colitis.

METHODS

C57BL/6 mice were injected (i.v.) with an adenoviral construct encoding the full-length murine adiponectin gene (AN+DSS) or a reporter-LacZ (Ctr and V+DSS groups) prior to DSS colitis protocol. In another experiment, mice with DSS colitis received either osmotin (Osm+DSS) or saline (DSS) via osmotic pumps. Disease progression and severity were evaluated using body weight, stool consistency, rectal bleeding, colon lengths, and histology. In vitro experiments were carried out in bone marrow-derived dendritic cells.

RESULTS

Mice overexpressing adiponectin had lower expression of proinflammatory cytokines (TNF, IL-1β), adipokines (angiotensin, osteopontin), and cellular stress and apoptosis markers. These mice had higher levels of IL-10, alternative macrophage marker, arginase 1, and leukoprotease inhibitor. The plant adiponectin homolog osmotin similarly improved colitis outcome and induced robust IL-10 secretion. LPS induced a state of adiponectin resistance in dendritic cells that was reversed by treatment with PPARγ agonist and retinoic acid.

CONCLUSION

Adiponectin exerted protective effects during murine DSS colitis. It had a broad activity that encompassed cytokines, chemotactic factors as well as processes that assure cell viability during stressful conditions. Reducing adiponectin resistance or using plant-derived adiponectin homologs may become therapeutic options in inflammatory bowel disease.

Dietary α-eleostearic acid ameliorates experimental inflammatory bowel disease in mice by activating peroxisome proliferator-activated receptor-γ

Background

Treatments for inflammatory bowel disease (IBD) are modestly effective and associated with side effects from prolonged use. As there is no known cure for IBD, alternative therapeutic options are needed. Peroxisome proliferator-activated receptor-gamma (PPARγ) has been identified as a potential target for novel therapeutics against IBD. For this project, compounds were screened to identify naturally occurring PPARγ agonists as a means to identify novel anti-inflammatory therapeutics for experimental assessment of efficacy.

Methodology/Principal Findings

Here we provide complementary computational and experimental methods to efficiently screen for PPARγ agonists and demonstrate amelioration of experimental IBD in mice, respectively. Computational docking as part of virtual screening (VS) was used to test binding between a total of eighty-one compounds and PPARγ. The test compounds included known agonists, known inactive compounds, derivatives and stereoisomers of known agonists with unknown activity, and conjugated trienes. The compound identified through VS as possessing the most favorable docked pose was used as the test compound for experimental work. With our combined methods, we have identified α-eleostearic acid (ESA) as a natural PPARγ agonist. Results of ligand-binding assays complemented the screening prediction. In addition, ESA decreased macrophage infiltration and significantly impeded the progression of IBD-related phenotypes through both PPARγ-dependent and –independent mechanisms in mice with experimental IBD.

Conclusions/Significance

This study serves as the first significant step toward a large-scale VS protocol for natural PPARγ agonist screening that includes a massively diverse ligand library and structures that represent multiple known target pharmacophores.

Pathophysiological Roles of PPARgamma in Gastrointestinal Epithelial Cells

Although the highest levels of PPARγ expression in the body have been reported in the gastrointestinal epithelium, little is known about the physiological functions of that receptor in the gut. Moreover, there is considerable controversy concerning the effects of thiazolidinedione PPARγ agonists on the two major diseases of the gastrointestinal track: colorectal cancer and inflammatory bowel disease. We will undertake to review both historical and recently published data with a view toward summarizing what is presently known about the roles of PPARγ in both physiological and pathological processes in the gastrointestinal epithelium.

Activated and inactivated PPARs-γ modulate experimentally induced colitis in rats

Background

This study sought to define the mechanism by which PPAR-γ ligands affect the course of experimentally induced colitis in rats.

Material/Methods

Inflammation was induced in Wistar rats by a single rectal administration of 2,4,6,-trinitrobenzene sulfonic acid (TNBS). The antagonist of PPARγ antagonist, bisphenol A diglycidyl ether (BADGE), was administrated intraperitoneally 120 mg/kg 4 times every other day. Rosiglitazone 8 mg/kg was administrated by gastric tube 4 times. Body weight was measured daily. After killing, the large intestinal tissue was weighed and collected for histopathologic and immunoenzymatic tests. Levels of IL-6, IL-10, and myeloperoxidase (MPO) were determined in serum and in intestinal homogenates.

Results

Rats receiving rosiglitazone had higher body weight, whereas large intestine weight/length ratio was lower; histology showed fewer inflammatory markers. Rats receiving TNBS and TNBS along with BADGE had more intensive inflammatory changes. Rosiglitazone alone decreased expression of IL-6; used with TNBS it decreased expression of MPO in intestinal tissue, yet did not increase the expression of IL-10. Decreased levels of MPO indicate reduced neutrophil-dependent immune response. The antagonist of PPAR-γ increased IL-6 in serum and decreased IL-10 in intestinal homogenates. Bisphenol A diglycidyl ether administrated to healthy animals increases serum IL-6 levels.

Conclusions

Rosiglitazone inhibits experimental inflammation; administration of its selective antagonist abolishes this protective influence. Rosiglitazone inhibits expression of proinflammatory IL-6 and does not affect IL-10. Agonists of PPARs-γ are possibilities for inflammatory bowel disease prevention. Exogenous substances blocking PPARs-γ may contribute to development or relapse of nonspecific inflammatory bowel diseases.

β-Caryophyllene inhibits dextran sulfate sodium-induced colitis in mice through CB2 receptor activation and PPARγ pathway

Cannabinoid receptor 2 (CB2) activation is suggested to trigger the peroxisome proliferator-activated receptor-γ (PPARγ) pathway, and agonists of both receptors improve colitis. Recently, the plant metabolite (E)-β-caryophyllene (BCP) was shown to bind to and activate CB2. In this study, we examined the anti-inflammatory effect of BCP in dextran sulfate sodium (DSS)-induced colitis and analyzed whether this effect was mediated by CB2 and PPARγ. Oral treatment with BCP reduced disease activity, colonic macro- and microscopic damage, myeloperoxidase and N-acetylglucosaminidase activities, and levels and mRNA expression of colonic tumor necrosis factor-α, IL-1β, interferon-γ, and keratinocyte-derived chemokine. BCP treatment also inhibited the activation of extracellular signal-regulated kinase 1/2, nuclear factor κB, IκB-kinase α/β, cAMP response element binding and the expression of caspase-3 and Ki-67. Moreover, BCP enhanced IL-4 levels and forkhead box P3 mRNA expression in the mouse colon and reduced cytokine levels (tumor necrosis factor-α, keratinocyte-derived chemokine, and macrophage-inflammatory protein-2) in a culture of macrophages stimulated with lipopolysaccharide. The use of the CB2 antagonist AM630 or the PPARγ antagonist GW9662 significantly reversed the protective effect of BCP. Confirming our results, AM630 reversed the beneficial effect of BCP on pro-inflammatory cytokine expression in IEC-6 cells. These results demonstrate that the anti-inflammatory effect of BCP involves CB2 and the PPARγ pathway and suggest BCP as a possible therapy for the treatment of inflammatory bowel disease.

Polymorphisms in NF-κB, PXR, LXR, PPARγ and risk of inflammatory bowel disease

AIM: To investigate the contribution of polymorphisms in nuclear receptors to risk of inflammatory bowel disease (IBD).

METHODS: Genotypes of nuclear factor (NF)-κB (NFKB1) NFκB -94ins/del (rs28362491); peroxisome proliferator-activated receptor (PPAR)-γ (PPARγ) PPARγ Pro12Ala (rs 1801282) and C1431T (rs 3856806); pregnane X receptor (PXR) (NR1I2) PXR A-24381C (rs1523127), C8055T (2276707), and A7635G (rs 6785049); and liver X receptor (LXR) (NR1H2) LXR T-rs1405655-C and T-rs2695121-C were assessed in a Danish case-control study of 327 Crohn’s disease patients, 495 ulcerative colitis (UC) patients, and 779 healthy controls. Odds ratio (OR) and 95% CI were estimated by logistic regression models.

RESULTS: The PXR A7635G variant, the PPARγ Pro12Ala and LXR T-rs2695121-C homozygous variant genotypes were associated with risk of UC (OR: 1.31, 95% CI: 1.03-1.66, P = 0.03, OR: 2.30, 95% CI: 1.04-5.08, P = 0.04, and OR: 1.41, 95% CI: 1.00-1.98, P = 0.05, respectively) compared to the corresponding homozygous wild-type genotypes. Among never smokers, PXR A7635G and the LXR T-rs1405655-C and T-rs2695121-C variant genotypes were associated with risk of IBD (OR: 1.41, 95% CI: 1.05-1.91, P = 0.02, OR: 1.63, 95% CI: 1.21-2.20, P = 0.001, and OR: 2.02, 95% CI: 1.36-2.99, P = 0.0005, respectively) compared to the respective homozygous variant genotypes. PXR A7635G (rs6785049) variant genotype was associated with a higher risk of UC diagnosis before the age of 40 years and with a higher risk of extensive disease (OR: 1.34, 95% CI: 1.03-1.75 and OR: 2.49, 95% CI: 1.24-5.03, respectively).

CONCLUSION: Common PXR and LXR polymorphisms may contribute to risk of IBD, especially among never smokers.

Lactobacillus plantarum ameliorates colonic epithelial barrier dysfunction by modulating the apical junctional complex and PepT1 in IL-10 knockout mice

Probiotics are efficacious in the treatment of inflammatory bowel disease. However, the precise mechanisms remain unknown. To determine whether probiotic Lactobacillus plantarum (LP) ameliorates colonic epithelial barrier dysfunction present in interleukin-10 knockout (IL-10⁻(/)⁻) mice, IL-10⁻(/)⁻ and wild-type mice received LP or the vehicle for 4 wk. Colitis was assessed by histological scores and clinical manifestation, and gut paracellular permeability was measured by Ussing chamber. Oligopeptide transporter 1 (PepT1)-mediated transepithelial transport was evaluated by measuring the plasma cephalexin concentration. The expression and distribution of apical junctional complex (AJC) proteins and PepT1 were determined by Western blotting and immunofluorescence and their mRNA by reverse transcriptase-PCR. Spontaneous colitis was observed in all IL-10⁻(/)⁻ mice in which paracellular permeability was increased, in conjunction with decreased expression and redistribution of zonula occludens-1, occludin, claudin-1, and β-catenin. PepT1 expression was increased, accompanied with an enhanced cephalexin transport. Colonic epithelial barrier dysfunction was further confirmed by increased bacterial translocation and proinflammatory cytokine production. Treatment with LP decreased colonic paracellular permeability with restoration of expression and distribution of AJC proteins and partially prevented PepT1 expression and cephalexin transport in IL-10⁻(/)⁻ mice. Moreover, treatment with LP also prevented bacterial translocation and proinflammatory cytokine production in IL-10⁻(/)⁻ mice. Results from this study indicated that treatment with LP may ameliorate colonic epithelial barrier dysfunction in IL-10⁻(/)⁻ mice, by modulating the AJC- and PepT1-mediated transepithelial transport.

Epoxyeicosatrienoic acids and soluble epoxide hydrolase: potential therapeutic targets for inflammation and its induced carcinogenesis

Chronic inflammation is an important factor contributing to human carcinoma, and non-steroidal anti-inflammatory drugs (NSAIDs) have been shown to have a preventive effect in the development of various types of carcinoma. However, NSAIDs also have adverse side effects including increased cardiovascular events, making them less than ideal for routine chemoprevention. Soluble epoxide hydrolase (sEH) is an enzyme that converts endogenous anti-inflammatory compounds, the epoxyeicosatrienoic acids (EETs), to the less anti-inflammatory dihydroxyeicosatrienoic acids (DHETs). Inhibition of sEH, by a highly selective and potent sEH inhibitor (sEHI), increases EETs leading to decreased inflammation. In our studies, administration of a sEHI in mouse colitis models led to decreased ulcer incidence and number of ulcers compared to controls, with no adverse side effects seen. In human tissue, sEH showed an increase in expression, as seen immunohistochemically, in ulcerative colitis (UC), UC-induced dysplasia, and UC-induced carcinoma. Thus, inhibition of sEH may be a novel biomarker and potential therapeutic target in inflammation and inflammation-induced carcinoma.

Topical rosiglitazone treatment improves ulcerative colitis by restoring peroxisome proliferator-activated receptor-gamma activity

OBJECTIVES

Impaired epithelial expression of peroxisome proliferator-activated receptor-gamma (PPARgamma) has been described in animal colitis models and briefly in patients with ulcerative colitis, but the functional significance in humans is not well defined. We examined PPARgamma expression and functional activity in human colonic epithelium and explored the potential of topical treatment with rosiglitazone (a PPARgamma ligand) in patients with ulcerative colitis.

METHODS

Spontaneous and rosiglitazone-mediated PPARgamma and adipophillin expression (a gene transcriptionally activated by PPARgamma) were measured by reverse transcriptase PCR in colonic biopsies and isolated epithelial cells from patients with ulcerative colitis and controls. Fourteen patients with active distal ulcerative colitis were randomized to either rosiglitazone (4 mg) or mesalazine (1 g) enema treatment once daily for 14 days.

RESULTS

PPARgamma expression was fourfold reduced in epithelial cells from inflamed compared with uninflamed mucosa and controls. Adipophillin levels were decreased in parallel. Rosiglitazone induced a concentration-dependent increase in adipophillin levels and restored PPARgamma activity in epithelial cells from inflamed mucosa in vitro. Rosiglitazone enema treatment was well tolerated and reduced the Mayo ulcerative colitis score from 8.9 to 4.3 (P<0.01), similar to the effect of mesalazine. Rosiglitazone increased adipophillin levels in the epithelial cells of the patients, indicating PPARgamma activation in vivo.

CONCLUSIONS

Roziglitasone enemas improve impaired PPARgamma activity in inflamed colonic epithelium and have beneficial clinical effect in patients with active distal ulcerative colitis. These findings raise interest in further studies of PPARgamma ligands that exhibit their anti-inflammatory effect locally in the gut to avoid possible systemic side effects.

PPARgamma agonists upregulate the barrier function of tight junctions via a PKC pathway in human nasal epithelial cells

Peroxisome proliferator activated (PPAR)gamma plays a critical role in the control of not only adipocyte differentiation, lipid metabolism and immunity but also the barrier functions of epithelial and endothelial cells. In the present study, to investigate effects of PPAR gamma agonists on the tight junctional barrier of human nasal epithelial cells (HNECs), hTERT-transfected HNECs, which highly express both PPAR gamma and tight junction proteins, were treated with the PPAR gamma agonists rosiglitazone and troglitazone. Treatment with the PPAR gamma agonists enhanced the barrier function of hTERT-transfected HNECs together with the upregulation of tight junction molecules claudin-1 and -4, occludin, and tricellulin at the transcriptional level. A significant increase of tight junction strands was also observed after treatment with rosiglitazone. Treatment with PPAR gamma agonists induced the activity of phospho-PKC in hTERT-transfected HNECs. The upregulation of the tight junction molecules in hTERT-transfected HNECs by rosiglitazone was inhibited by not only PPAR gamma antagonists GW9662 and T0070907, but also the panPKC inhibitor GF109203X. These findings suggest that PPAR gamma agonists upregulate the barrier function of tight junctions of human nasal epithelial cells via a PKC signaling pathway and could be novel drugs for protection against inhaled substances and pathogens in the airway epithelium of human nasal mucosa.

Nrf2-regulated PPAR{gamma} expression is critical to protection against acute lung injury in mice

RATIONALE

The NF-E2 related factor 2 (Nrf2)-antioxidant response element (ARE) pathway is essential for protection against oxidative injury and inflammation including hyperoxia-induced acute lung injury. Microarray expression profiling revealed that lung peroxisome proliferator activated receptor gamma (PPARgamma) induction is suppressed in hyperoxia-susceptible Nrf2-deficient (Nrf2(-/-)) mice compared with wild-type (Nrf2(+/+)) mice. PPARgamma has pleiotropic beneficial effects including antiinflammation in multiple tissues.

OBJECTIVES

We tested the hypothesis that PPARgamma is an important determinant of pulmonary responsivity to hyperoxia regulated by Nrf2.

METHODS

A computational bioinformatic method was applied to screen potential AREs in the Pparg promoter for Nrf2 binding. The functional role of a potential ARE was investigated by in vitro promoter analysis. A role for PPARgamma in hyperoxia-induced acute lung injury was determined by temporal silencing of PPARgamma via intranasal delivery of PPARgamma-specific interference RNA and by administration of a PPARgamma ligand 15-deoxy-Delta(12,14)-prostaglandin J(2) in mice.

MEASUREMENTS AND MAIN RESULTS

Deletion or site-directed mutagenesis of a potential ARE spanning -784/-764 sequence significantly attenuated hyperoxia-increased Pparg promoter activity in airway epithelial cells overexpressing Nrf2, indicating that the -784/-764 ARE is critical for Nrf2-regulated PPARgamma expression. Mice with decreased lung PPARgamma by specific interference RNA treatment had significantly augmented hyperoxia-induced pulmonary inflammation and injury. 15 Deoxy-Delta(12,14)-prostaglandin J(2) administration significantly reduced hyperoxia-induced lung inflammation and edema in Nrf2(+/+), but not in Nrf2(-/-) mice.

CONCLUSIONS

Results indicate for the first time that Nrf2-driven PPARgamma induction has an essential protective role in pulmonary oxidant injury. Our observations provide new insights into the therapeutic potential of PPARgamma in airway oxidative inflammatory disorders.

Nitrated oleic acid up-regulates PPARgamma and attenuates experimental inflammatory bowel disease

Nitric oxide and its metabolites undergo nitration reactions with unsaturated fatty acids during oxidative inflammatory conditions, forming electrophilic nitro-fatty acid derivatives. These endogenous electrophilic mediators activate anti-inflammatory signaling reactions, serving as high-affinity ligands for peroxisome proliferator-activated receptor gamma (PPARgamma). Here we examined the therapeutic effects of 9- or 10-nitro-octadecenoic oleic acid (OA-NO(2)) and native oleic acid (OA) in a mouse model of colitis. OA-NO(2) reduced the disease activity index and completely prevented dextran sulfate sodium-induced colon shortening and the increase in colonic p65 expression. Increased PPARgamma expression was observed in colon samples as well as in cells after OA-NO(2) administration, whereas no effect was seen with OA. This induction of PPARgamma expression was completely abolished by the PPARgamma antagonist GW9662. 5-Aminosalicylic acid, an anti-inflammatory drug routinely used in the management of inflammatory bowel disease, also increased PPARgamma expression but to a lesser extent. Altogether, these findings demonstrate that administration of OA-NO(2) attenuates colonic inflammation and improves clinical symptoms in experimental inflammatory bowel disease. This protection involves activation of colonic PPARgamma.

Latent autoimmune diabetes in adults

CONTEXT

Autoantibodies that are reactive to islet antigens are present at the time of diagnosis in most patients with type 1 diabetes. Additionally, approximately 10% of phenotypic type 2 diabetic patients are positive for at least one of the islet autoantibodies, and this group is often referred to as "latent autoimmune diabetes in adults (LADA)." These patients share many genetic and immunological similarities with type 1 diabetes, suggesting that LADA, like type 1 diabetes, is an autoimmune disease. However, there are differences in autoantibody clustering, T cell reactivity, and genetic susceptibility and protection between type 1 diabetes and LADA, implying important differences in the underlying disease processes.

EVIDENCE ACQUISITION AND SYNTHESIS

In this clinical review, we will summarize the current understanding of LADA based on the MEDLINE search of all peer-reviewed publications (original articles and reviews) on this topic between 1974 and 2009.

CONCLUSIONS

In LADA, diabetes occurs earlier in the beta-cell-destructive process because of the greater insulin resistance. Complexities arise also because of variable definitions of LADA and type 1 diabetes in adults. As immunomodulatory therapies that slow or halt the type 1 diabetes disease process are discovered, testing these therapies in LADA will be essential.

Current understanding of the role of PPARγ in gastrointestinal cancers

Numerous studies have indicated that PPARγ plays multiple roles such as in inflammation, cell cycle control, cell proliferation, apoptosis, and carcinogenesis, thus PPARγ contributes to the homeostasis. Many in vitro studies have showed that ligand-induced activation of PPARγ possess antitumor effect in many cancers including CRC. However, the role of PPARγ in gastrointestinal cancers, especially in colorectal cancer, is rather controversial. Nevertheless, some recent studies with the positive results on the possible application of PPARγ ligands, such as Bezafibrate or Rosiglitazone in gastrointestinal cancers, have suggested a potential usefulness of PPARγ agonists in cancer prevention and therapy. In this review, the authors discuss the recent developments in the role of PPARγ in gastrointestinal cancers.