Peroxisome proliferator-activated receptor-γ is downregulated in ulcerative colitis and is involved in experimental colitis-associated neoplasia

Qin-Yu-Qing-Chang decoction reshapes colonic metabolism by activating PPAR-γ signaling to inhibit facultative anaerobes against DSS-induced colitis

BACKGROUND

Qin-Yu-Qing-Chang decoction (QYQC), an herbal formula from China, is extensively employed to manage ulcerative colitis (UC) and exhibits potential benefits for colonic function. Nevertheless, the fundamental molecular mechanisms of QYQC remain largely uncharted.

METHODS

The primary constituents of QYQC were determined utilizing UHPLC-MS/MS analysis and the effectiveness of QYQC was assessed in a mouse model of colitis induced by dextran sulfate sodium. Evaluations of colon inflammatory responses and mucosal barrier function were thoroughly assessed. RNA sequencing, molecular docking, colonic energy metabolism, and 16S rRNA sequencing analysis were applied to uncover the complex mechanisms of QYQC in treating UC. Detect the signal transduction of the peroxisome proliferator-activated receptor-γ (PPAR-γ) both in the nucleus and cytoplasm. Furthermore, a PPAR-γ antagonist was strategically utilized to confirm the functional targets that QYQC exerts.

RESULTS

Utilizing UHPLC-MS/MS, the principal constituents of the nine traditional Chinese medicinal herbs comprising QYQC were systematically identified. QYQC treatment substantially ameliorated colitis in mice, as evidenced by the improvement in symptoms and the reduction in colonic pathological injuries. Besides, QYQC treatment mitigated the inflammatory response and improved mucosal barrier function. Furthermore, QYQC enhanced the mitochondria citrate cycle (TCA cycle) by triggering PPAR-γ signaling and increasing the proportion of PPAR-γ entering the nucleus. This prevented the unconstrained expansion of facultative anaerobes, particularly pathogenic Escherichia coli (E. coli, family Enterobacteriaceae) and thus improved colitis. Results of molecular docking indicated that the representative chemical components of QYQC including Baicalin, Paeoniflorin, Mollugin, and Imperatorin bound well with PPAR-γ. The impact of QYQC on colitis was diminished in the presence of a PPAR-γ antagonist.

CONCLUSIONS

In summary, QYQC ameliorates UC by activating PPAR-γ signaling and increasing the proportion of PPAR-γ entering the nucleus, which enhances the energy metabolism of intestinal epithelial cells and thereby preventing the uncontrolled proliferation of facultative anaerobes.

Pioglitazone as a potential modulator in autoimmune diseases: a review on its effects in systemic lupus erythematosus, psoriasis, inflammatory bowel disease, and multiple sclerosis

INTRODUCTION

Current medications for autoimmune disorders often induce broad-ranging side effects, prompting a growing interest in therapies with more specific immune system modulation. Pioglitazone, known for its anti-diabetic properties, is increasingly recognized for significant immunomodulatory potential. Beyond its traditional use in diabetes management, pioglitazone emerges as a promising therapeutic candidate for autoimmune disorders.

AREAS COVERED

This comprehensive review explores pioglitazone's impact on four prominent autoimmune conditions: systemic lupus erythematosus, psoriasis, inflammatory bowel disease, and multiple sclerosis. We focus on pioglitazone's diverse effects on immune cells and cytokines in these diseases, highlighting its potential as a valuable therapeutic option for autoimmune diseases. Here we have reviewed the latest and most current research literature available on PubMed, based on research published in the last 15 years.

EXPERT OPINION

Pioglitazone as an immunomodulatory agent can regulate T cell differentiation, inhibit inflammatory cytokines, and promote anti-inflammatory macrophages. While further clinical studies are needed to fully understand its mechanisms and optimize treatment strategies, pioglitazone represents a potential therapeutic approach to improve outcomes for patients with these challenging autoimmune conditions. The future of autoimmune disease research may involve personalized treatment approaches, and collaborative efforts to improve patient quality of life.

Mechanic evaluation of Wu-Mei-Pill on colitis-associated colorectal cancer: An integrated transcriptomics, metabolomics, and experimental validation study

BACKGROUND

Chronic intestinal inflammatory diseases play a crucial role in the onset of colorectal cancer (CRC). Effectively impeding the progression of colitis-associated colorectal cancer (CAC) can be instrumental in hindering CRC development. Wu-Mei-Pill (WMP), a formulation comprising various herbal extracts, is clinically employed for CAC treatment, yet the underlying mechanism of WMP's efficacy in CAC remains unclear. Our study firstly demonstrated the effects and mechanisms of WMP on transcriptional and metabolic levels based on integrated transcriptomics and untargeted metabolomics and relative experimental validations.

MATERIALS AND METHODS

A CAC mouse model was established through a single injection of azoxymethane (AOM) followed by intermittent dextran sodium sulfate (DSS) intervention, with subsequent WMP administration. Initially, the therapeutic impact of WMP on the CAC model was assessed by observing survival rate, body weight change, colon length, tumor number, tumor load, and pathological changes in the colon tissue of CAC mice post-WMP intervention. Subsequently, differential genes and metabolites in the colorectal tissue of CAC mice following WMP intervention were identified through transcriptomics and non-targeted metabolomics. Finally, the influence of WMP on the peroxisome proliferator activated receptor (PPAR) pathway, Wnt pathway, and CC motif chemokine ligand 3 (CCL3)/ CC motif chemokine receptor 1 (CCR1) axis in CAC mice was verified through western blot, immunofluorescence, and ELISA based on the results of transcriptomics and non-targeted metabolomics.

RESULTS

WMP intervention enhanced survival, alleviated body weight loss, shortened colon length, tumor occurrence, and pathological changes in the colorectal tissue of CAC mice, such as glandular damage, tumourigenesis, and inflammatory cell infiltration. Transcriptomic and non-targeted metabolomic results revealed that WMP intervention up-regulated the expression of key regulatory mechanisms of fatty acid oxidation PPAR pathway-related genes (Pparg, Ppara, Cpt1a, and Acadm) and metabolites (L-carnitine and L-palmitoylcarnitine). Additionally, it down-regulated Wnt pathway-related genes (Wnt3, Axin2, Tcf7, Mmp7, Lgr5, Wnt5a, Fzd6, Wnt7b, Lef1, and Fzd10 etc.) and pro-inflammatory related genes (Il1b, Il6, Il17a, Ccl3, and Ccr1 etc.). Experimental validation demonstrated that WMP up-regulated PPAR pathway-related proteins [PPARγ, PPARα, carnitine palmitoyltransferase 1A (CPT1A), and acyl-CoA dehydrogenase medium chain (ACADM)] in the colorectal tissue of CAC mice. It also down-regulated Wnt pathway-related proteins [β-catenin, T-cell factor (TCF), lymphoid enhancer-binding factor (LEF), and matrix metallopeptidase 7 (MMP7)], inhibited the nuclear translocation of the key transcription factor β-catenin in the Wnt pathway, and suppressed epithelial-to-mesenchymal transition (EMT) activation induced by the Wnt pathway (up-regulated E-cadherin and down-regulated Vimentin). Furthermore, WMP intervention reduced pro-inflammatory factors [interleukin (IL)-6, IL-1β, and IL-17A] and decreased CCL3/CCR1 axis factors, including CCL3 protein levels and diminished F4/80+CCR1+ positive expressed cells.

CONCLUSION

WMP significantly inhibits CAC tumorigenesis by up-regulating PPARα-mediated fatty acid oxidation, inhibiting the Wnt signaling pathway-mediated EMT, and suppressing CCL3/CCR1-mediated inflammatory responses.

Effects of polyphenolic maqui (Aristotelia chilensis) extract on the inhibition of NLRP3 inflammasome and activation of mast cells in a mouse model of Crohn's disease-like colitis

Introduction

Crohn's disease (CD) involves activation of mast cells (MC) and NF-кB in parallel with the PPAR-α/NLRP3 inflammasome/IL-1β pathway in the inflamed colon. Whether polyphenols from maqui (Aristotelia chilensis) represent a natural alternative treatment for CD is unclear. Therefore, we used an animal model of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced CD-like colitis to investigate protective effects of maqui extract through monitoring NLRP3 inflammasome and MC activation in colon tissue.

Methods

Maqui extract was administered via orogastric route to mice after (post-Treatment group) or prior (pre-Treatment group) to TNBS-induction. Colon pathology was characterized by histoarchitectural imaging, disease activity index (DAI), and assessing NF-кB, p-NF-кB, PPAR-α/NLRP3 expression and IL-1β levels.

Results

Compared to mice treated with TNBS alone administration of anthocyanin-rich maqui extract improved the DAI, colon histoarchitecture and reduced both colon wet-weight and transmural inflammation. Induction with TNBS significantly increased colonic NLPR3 inflammasome activation, while co-treatment with maqui extract (either post- or pre-Treatment) significantly downregulated NLRP3, ASC and caspase-1 levels, which manifested as reduced colonic IL-1β levels. Supplemented maqui extract marginally diminished NF-кB activity in epithelial cells but reached statistical significance in immune cells (as judged by decreased NF-кB phosphorylation). PPAR-α signaling was largely unaffected by Maqui whereas MC infiltration into the colon mucosa and submucosa decreased and their level of degranulation was suppressed.

Conclusion

These outcomes show the post- and pre- Treatment effect of a polyphenolic extract rich in anthocyanins from maqui the acute phase of TNBS- induced CD-like colitis is linked to suppression of the NLRP3 inflammasome and reduced MC responses. These data indicate that maqui extract represents a potential nutraceutical for the treatment of inflammatory bowel disease (IBD).

Astragaloside IV inhibits AOM/DSS-induced colitis-associated tumorigenesis via activation of PPARγ signaling in mice

BACKGROUND

Colitis-associated colorectal cancer (CAC) is a severe complication of inflammatory bowel disease (IBD), resulting from long-term inflammation in the intestines. The primary cause of CAC is the imbalance of oxidative metabolism in intestinal cells, triggered by excessive reactive oxygen (ROS) and nitrogen (NO) species production due to prolonged intestinal inflammation. This imbalance leads to genomic instability caused by DNA damage, eventually resulting in the development of intestinal cancer. Previous studies have demonstrated that astragaloside IV is effective in treating dextran sulfate sodium salt (DSS)-induced colitis, but there is currently no relevant research on its efficacy in treating CAC.

METHODS

To investigate the effect of astragaloside IV against CAC and the underlying mechanism, C57 mice were treated with (20, 40, 80 mg/kg) astragaloside IV while CAC was induced by intraperitoneal injection of 10 mg/kg azoxymethane (AOM) and ad libitum consumption of 2% dextran sulfate sodium salt (DSS). We re-verified the activating effects of astragaloside IV on PPARγ signaling in IEC-6 cells, which were reversed by GW9662 (the PPARγ inhibitor).

RESULTS

Our results showed that astragaloside IV significantly improved AOM/DSS-induced CAC mice by inhibiting colonic shortening, preventing intestinal mucosal damage, reducing the number of tumors and, the expression of Ki67 protein. In addition, astragaloside IV could activate PPARγ signaling, which not only promoted the expression of Nrf2 and HO-1, restored the level of SOD, CAT and GSH, but also inhibited the expression of iNOS and reduced the production of NO in the intestine and IEC-6 cells. And this effect could be reversed by GW9662 in vitro. Astragaloside IV thus decreased the level of ROS and NO in the intestinal tract of mice, as well as reduced the damage of DNA, and therefore inhibited the occurrence of CAC.

CONCLUSION

Astragaloside IV can activate PPARγ signaling in intestinal epithelial cells and reduces DNA damage caused by intestinal inflammation, thereby inhibiting colon tumourigenesis. The novelty of this study is to use PPARγ as the target to inhibit DNA damage to prevent the occurrence of CAC.

C4BP(β-)-mediated immunomodulation attenuates inflammation in DSS-induced murine colitis and in myeloid cells from IBD patients

The most recent and promising therapeutic strategies for inflammatory bowel disease (IBD) have engaged biologics targeting single effector components involved in major steps of the immune-inflammatory processes, such as tumor necrosis factor, interleukins or integrins. Nevertheless, these molecules have not yet met expectations regarding efficacy and safety, resulting in a significant percentage of refractory or relapsing patients. Thus, novel treatment options are urgently needed. The minor isoform of the complement inhibitor C4b-binding protein, C4BP(β-), has been shown to confer a robust anti-inflammatory and immunomodulatory phenotype over inflammatory myeloid cells. Here we show that C4BP(β-)-mediated immunomodulation can significantly attenuate the histopathological traits and preserve the intestinal epithelial integrity in dextran sulfate sodium (DSS)-induced murine colitis. C4BP(β-) downregulated inflammatory transcripts, notably those related to neutrophil activity, mitigated circulating inflammatory effector cytokines and chemokines such as CXCL13, key in generating ectopic lymphoid structures, and, overall, prevented inflammatory immune cell infiltration in the colon of colitic mice. PRP6-HO7, a recombinant curtailed analogue with only immunomodulatory activity, achieved a similar outcome as C4BP(β-), indicating that the therapeutic effect is not due to the complement inhibitory activity. Furthermore, both C4BP(β-) and PRP6-HO7 significantly reduced, with comparable efficacy, the intrinsic and TLR-induced inflammatory markers in myeloid cells from both ulcerative colitis and Crohn's disease patients, regardless of their medication. Thus, the pleiotropic anti-inflammatory and immunomodulatory activity of PRP6-HO7, able to "reprogram" myeloid cells from the complex inflammatory bowel environment and to restore immune homeostasis, might constitute a promising therapeutic option for IBD.

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

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

Perindopril/Ambrosin Combination Mitigates Dextran Sulfate Sodium-Induced Colitis in Mice: Crosstalk between Toll-like Receptor 4, the Pro-Inflammatory Pathways, and SIRT1/PPAR-γ Signaling

Colitis is one of the inflammatory states that affect the intestinal wall and may even predispose to malignancy due to chronic irritation. Although the etiology of colitis is not yet fully explored, a combination of genetic and environmental factors is strongly incriminated. Perindopril is an angiotensin-converting enzyme inhibitor that is used for the management of a wide range of cardiovascular diseases. Ambrosin is a sesquiterpene lactone that was proven to have beneficial effects in disorders characterized by inflammatory nature. The objective of this study is to make a comparison between the effects of perindopril or ambrosin on dextran sulfate sodium (DSS)-induced colitis in mice and to explore the effect of their combination. The present findings indicate that each ambrosin or perindopril alone or in combination is able to ameliorate oxidative stress and suppress the proinflammatory pathways in the colonic tissues of DSS-treated mice via mechanisms related to toll-like receptor 4/nuclear factor kappa B signaling and modulation of peroxisome proliferator-activated receptor gamma/sirtuin-1 levels. In addition, each ambrosin or perindopril alone or in combination inhibits apoptosis and augments the mediators of autophagy in DSS-treated mice. These effects are reflected in the amelioration of the histopathological and electron microscopic changes in the colonic tissues. Interestingly, the most remarkable effects are those encountered with the perindopril/ambrosin combination compared to the groups treated with each of these agents alone. In conclusion, the perindopril/ambrosin combination might represent an effective modality for mitigation of the pathogenic events and the clinical sequelae of colitis.

IBD Subtype-Regulators IFNG and GBP5 Identified by Causal Inference Drive More Intense Innate Immunity and Inflammatory Responses in CD Than Those in UC

Background: The pathological differences between Crohn’s disease (CD) and ulcerative colitis (UC) are substantial and unexplained yet. Here, we aimed to identify potential regulators that drive different pathogenesis of CD and UC by causal inference analysis of transcriptome data.

Methods: Kruskal–Wallis and Dunnett’s tests were performed to identify differentially expressed genes (DEGs) among CD patients, UC patients, and controls. Subsequently, differentially expressed pathways (DEPs) between CD and UC were identified and used to construct the interaction network of DEPs. Causal inference was performed to identify IBD subtype-regulators. The expression of the subtype-regulators and their downstream genes was validated by qRT-PCR with an independent cohort.

Results: Compared with the control group, we identified 1,352 and 2,081 DEGs in CD and UC groups, respectively. Multiple DEPs between CD and UC were closely related to inflammation-related pathways, such as NOD-like receptor signaling, IL-17 signaling, and chemokine signaling pathways. Based on the priori interaction network of DEPs, causal inference analysis identified IFNG and GBP5 as IBD subtype-regulators. The results with the discovery cohort showed that the expression level of IFNG, GBP5, and NLRP3 was significantly higher in the CD group than that in the UC group. The regulation relationships among IFNG, GBP5, and NLRP3 were confirmed with transcriptome data from an independent cohort and validated by qRT-PCR.

Conclusion: Our study suggests that IFNG and GBP5 were IBD subtype-regulators that trigger more intense innate immunity and inflammatory responses in CD than those in UC. Our findings reveal pathomechanical differences between CD and UC that may contribute to personalized treatment for CD and UC.

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.

Expression of Oxidative Phosphorylation Complexes and Mitochondrial Mass in Pediatric and Adult Inflammatory Bowel Disease

INTRODUCTION

Inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), is a multifactorial intestinal disorder but its precise etiology remains elusive. As the cells of the intestinal mucosa have high energy demands, mitochondria may play a role in IBD pathogenesis. The present study is aimed at evaluating the expression levels of mitochondrial oxidative phosphorylation (OXPHOS) complexes in IBD. Material and Methods. 286 intestinal biopsy samples from the terminal ileum, ascending colon, and rectum from 124 probands (34 CD, 33 UC, and 57 controls) were stained immunohistochemically for all five OXPHOS complexes and the voltage-dependent anion-selective channel 1 protein (VDAC1 or porin). Expression levels were compared in multivariate models including disease stage (CD and UC compared to controls) and age (pediatric/adult).

RESULTS

Analysis of the terminal ileum of CD patients revealed a significant reduction of complex II compared to controls, and a trend to lower levels was evident for VDAC1 and the other OXPHOS complexes except complex III. A similar pattern was found in the rectum of UC patients: VDAC1, complex I, complex II, and complex IV were all significantly reduced, and complex III and V showed a trend to lower levels. Reductions were more prominent in older patients compared to pediatric patients and more marked in UC than CD.

CONCLUSION

A reduced mitochondrial mass is present in UC and CD compared to controls. This is potentially a result of alterations of mitochondrial biogenesis or mitophagy. Reductions were more pronounced in older patients compared to pediatric patients, and more prominent in UC than CD. Complex I and II are more severely compromised than the other OXPHOS complexes. This has potential therapeutic implications, since treatments boosting biogenesis or influencing mitophagy could be beneficial for IBD treatment. Additionally, substances specifically stimulating complex I activity should be tested in IBD treatment.

Parsing the Role of PPARs in Macrophage Processes

Cells are richly equipped with nuclear receptors, which act as ligand-regulated transcription factors. Peroxisome proliferator activated receptors (PPARs), members of the nuclear receptor family, have been extensively studied for their roles in development, differentiation, and homeostatic processes. In the recent past, there has been substantial interest in understanding and defining the functions of PPARs and their agonists in regulating innate and adaptive immune responses as well as their pharmacologic potential in combating acute and chronic inflammatory disease. In this review, we focus on emerging evidence of the potential roles of the PPAR subtypes in macrophage biology. We also discuss the roles of dual and pan PPAR agonists as modulators of immune cell function, microbial infection, and inflammatory diseases.

The Emerging Role of COX-2, 15-LOX and PPARγ in Metabolic Diseases and Cancer: An Introduction to Novel Multi-target Directed Ligands (MTDLs)

Emerging evidence supports an intertwining framework for the involvement of different inflammatory pathways in a common pathological background for a number of disorders. Of importance are pathways involving arachidonic acid metabolism by cyclooxygenase-2 (COX-2) and 15-lipoxygenase (15-LOX). Both enzyme activities and their products are implicated in a range of pathophysiological processes encompassing metabolic impairment leading to adipose inflammation and the subsequent vascular and neurological disorders, in addition to various pro- and antitumorigenic effects. A further layer of complexity is encountered by the disparate, and often reciprocal, modulatory effect COX-2 and 15-LOX activities and metabolites exert on each other or on other cellular targets, the most prominent of which is peroxisome proliferator-activated receptor gamma (PPARγ). Thus, effective therapeutic intervention with such multifaceted disorders requires the simultaneous modulation of more than one target. Here, we describe the role of COX-2, 15-LOX, and PPARγ in cancer and complications of metabolic disorders, highlight the value of designing multi-target directed ligands (MTDLs) modifying their activity, and summarizing the available literature regarding the rationale and feasibility of design and synthesis of these ligands together with their known biological effects. We speculate on the potential impact of MTDLs in these disorders as well as emphasize the need for structured future effort to translate these early results facilitating the adoption of these, and similar, molecules in clinical research.

Pioglitazone-Mediated Attenuation of Experimental Colitis Relies on Cleaving of Annexin A1 Released by Macrophages

Ulcerative colitis and Crohn's disease are chronic inflammatory bowel diseases (IBDs) which burden health systems worldwide; available pharmacological therapies are limited and cost-intensive. Use of peroxisome proliferator activated-receptor γ (PPARγ) ligands for IBD treatment, while promising, lacks solid evidences to ensure its efficacy. Annexin A1 (AnxA1), a glucocorticoid-modulated anti-inflammatory protein, plays a key role on IBD control and is a potential biomarker of IBD progression. We here investigated whether effects of pioglitazone, a PPARγ ligand, rely on AnxA1 actions to modulate IBD inflammation. Experimental colitis was evoked by 2% dextran sodium sulfate (DSS) in AnxA1 knockout (AnxA1^-/-) or wild type (WT) C57BL/6 mice. Clinical and histological parameters were more severe for AnxA^-/- than WT mice, and 10 mg/kg pioglitazone treatment attenuated disease parameters in WT mice only. AnxA1 expression was increased in tissue sections of diseased WT mice, correlating positively with presence of CD68⁺ macrophages. Metalloproteinase-9 (MMP-9) and inactive 33 kDa AnxA1 levels were increased in the colon of diseased WT mice, which were reduced by pioglitazone treatment. Cytokine secretion, reactive oxygen species generation and MMP-9 expression caused by lipopolysaccharide (LPS) treatment in AnxA1-expressing RAW 264.7 macrophages were reduced by pioglitazone treatment, effects not detected in AnxA1 knockdown macrophages. LPS-mediated increase of AnxA1 cleaving in RAW 264.7 macrophages was also attenuated by pioglitazone treatment. Finally, pioglitazone treatment increased extracellular signal-regulated kinase (ERK) phosphorylation in AnxA1-expressing RAW 264.7 macrophages, but not in AnxA1-knockdown macrophages. Thus, our data highlight AnxA1 as a crucial factor for the therapeutic actions of pioglitazone on IBDs.

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.

Transcriptional programmes underlying cellular identity and microbial responsiveness in the intestinal epithelium

The intestinal epithelium serves the unique and critical function of harvesting dietary nutrients, while simultaneously acting as a cellular barrier separating tissues from the luminal environment and gut microbial ecosystem. Two salient features of the intestinal epithelium enable it to perform these complex functions. First, cells within the intestinal epithelium achieve a wide range of specialized identities, including different cell types and distinct anterior-posterior patterning along the intestine. Second, intestinal epithelial cells are sensitive and responsive to the dynamic milieu of dietary nutrients, xenobiotics and microorganisms encountered in the intestinal luminal environment. These diverse identities and responsiveness of intestinal epithelial cells are achieved in part through the differential transcription of genes encoded in their shared genome. Here, we review insights from mice and other vertebrate models into the transcriptional regulatory mechanisms underlying intestinal epithelial identity and microbial responsiveness, including DNA methylation, chromatin accessibility, histone modifications and transcription factors. These studies are revealing that most transcription factors involved in intestinal epithelial identity also respond to changes in the microbiota, raising both opportunities and challenges to discern the underlying integrative transcriptional regulatory networks.

Integrative Analysis of Transcriptomic and Proteomic Profiling in Inflammatory Bowel Disease Colon Biopsies

BACKGROUND

Crohn's disease (CD) and ulcerative colitis (UC) are intestinal chronic inflammatory conditions characterized by altered epithelial barrier function and tissue damage. Despite significant efforts to understanding the biological mechanisms responsible for gut inflammation, the pathophysiology of CD and UC remains poorly understood.

METHODS

To help elucidate the potential mechanisms responsible for gut inflammation in CD and UC, transcriptomic and proteomic profiling of human colon biopsy specimens was performed. Dysregulated genes and proteins in disease tissues compared with normal tissues were characterized from the expression profiles and further subjected to pathway analysis to identify altered biological processes and signaling pathways.

RESULTS

Sample analysis showed 4250 genes with matched protein expression and a wide range of correlation of RNA-protein abundance across samples. Pathway analysis of dysregulated genes and proteins in CD and UC showed alterations in immune and inflammatory responses, complement cascade, and the suppression of metabolic processes and PPAR signaling. In CD, increased T-helper cell differentiation and elevated toll-like receptor and JAK/STAT signaling were observed. Interestingly, increased MAPK signaling was only observed in UC. Weighted gene co-expression network analysis suggested a possible role of epigenetic regulation in UC. Of note, a large discrepancy between regulation of RNA and protein levels in inflamed colon samples was detected for previously identified biomarkers including MMP14 and LAMP1.

CONCLUSIONS

With the analysis of dysregulated genes and pathways, the present study unravels key mechanisms contributing to CD and UC pathogenesis and emphasizes that integrative analysis of multi-omics data sets can provide more insight into understanding complex disease mechanisms.

Effect of Long-Term Mesalamine Therapy on Cancer-Associated Gene Expression in Colonic Mucosa of Patients with Ulcerative Colitis

BACKGROUND

The role of 5-aminosalicylic acid (5-ASA or mesalamine) in the prevention of colorectal cancer in ulcerative colitis (UC) patients was reported, but the effect on molecular targets in UC colon mucosa is unknown.

AIM

This observational study evaluates gene expression levels of 5-ASA targets using serial colon biopsy specimens from UC patients undergoing long-term 5-ASA therapy.

METHODS

Transcript levels were compared between colonoscopic biopsy specimens collected from 62 patients at initial and final follow-up colonoscopy at 2-6 years. All patients had mild-to-moderate UC and were undergoing long-term 5-ASA maintenance. Stepwise multiple linear regression analyses were performed to correlate changes in transcript levels with therapeutic response (Mayo clinical score endoscopy and DAI and/or Nancy histopathology score) and nonclinical variables.

RESULTS

The transcript levels of colorectal carcinogenesis-associated known 5-ASA target genes were significantly reduced after prolonged 5-ASA therapy (P < 0.005-0.03). Multiple linear regression models predicted significant association between transcript levels of Ki-67, NF-kB (p65), PPARγ, COX-2 and IL-8, CDC25A, and CXCL10 with duration of drug (5-ASA) exposure (P ≤ 0.05). Ki-67, NF-kB (p65), and CXCL10 transcripts were also correlated with reduced endoscopy sub-score (P ≤ 0.05). COX-2, IL-8, CDC25A, and TNF transcripts strongly correlated with DAI sub-scores (P ≤ 0.05). Only COX-2 and IL-8 transcript levels correlated (P ≤ 0.05) with Nancy histological score.

CONCLUSION

This study provides molecular evidence of changes in carcinogenesis-related targets/pathways in colon tissue during long-term 5-ASA maintenance therapy that may contribute to the observed chemopreventive effects of 5-ASA in UC patients.

PGlyRP3 concerts with PPARγ to attenuate DSS-induced colitis in mice

Nutrients may modulate immunity through their transcription factors that act on both metabolic and immunity genes. It has been shown that the transcription factor of lipid ligands PPARγ physically binds the gene promoter of the peptidoglycan recognition protein (PGlyRP3), which showed anti-inflammatory action in vitro. It is hypothesized in the present work that olive oil feeding protects against toxicity of DSS-induced colitis via activation of the lipid transcription factor PPARγ that stimulates the anti-inflammatory PGlyRP3. Results: PGlyRP3 is expressed in mouse colon and up-regulated by olive oil feeding. Olive oil reduced mortality and severity scores of DSS-induced colitis and down-regulated the proinflammatory IL-1b, IL-6 and TNFα genes. This protective effect was accompanied by up-regulation of both PPARγ and PGlyRP3. Inhibition of PPARγ by its antagonist BADGE down-regulated PGlyRP3 and abolished the anti-inflammatory effect of olive oil feeding in this DSS-induced colitis model, reflecting the pivotal role of PPARγ binding nutrition and inflammation. Activation of PGlyRP3 by its ligand peptidoglycan was not responsible for the inflammation caused by peptidoglycan, since neutralization of TLR2 attenuated this inflammatory response without affecting the peptidoglycan-induced PGlyRP3 level. Olive oil activated the IκBα and inhibited NF-κB and cox-2 gene expressions, and p65 nuclear translocation in DSS-colitis mice, reflecting the involvement of the inhibition of NF-κB signaling pathway in the anti-inflammatory olive oil - PPARγ - PGlyRP3 access. This pathway was reactivated by the PPARγ antagonist BADGE. Conclusions: Olive oil regulates by the same transcription factor (PPARγ) both lipid metabolic and immune gene (PGlyRP3) expressions, exerting the anti-inflammatory effect, and protecting against DSS-induced colitis in mice.

β-Catenin Regulation in Sporadic Colorectal Carcinogenesis: Not as Simple as APC

BACKGROUND

The wnt/APC/β-catenin pathway is a critical initiator in colorectal carcinogenesis in both hereditary and sporadic colorectal cancer (CRC). The progression of this process remains incompletely understood, although inflammation is pivotal. Drivers of inflammation are elevated in malignant tissue and have been shown to regulate β-catenin expression. Interleukin-17A (IL-17A) is protumorigenic at elevated levels via COX-2 stimulation. Elevated peroxisome proliferator-activated receptor γ (PPARγ) expression has reduced risk of carcinogenesis and good overall prognosis in established CRC. Activation of PPARγ has inhibitory effect on β-catenin.

METHODS

Using qPCR and IHC, we compared β-catenin, PPARγ, COX-2, and IL-17A in the colonic mucosa of patients with sporadic CRC, inflammatory bowel disease (IBD), and irritable bowel syndrome (IBS), against a normal control population.

RESULTS

β-catenin mRNA and protein expression progressively increased from the Normal group, through IBS and IBD reaching statistical significance in CRC. COX-2 mRNA levels increased similarly with statistical significance in IBD and CRC. However, COX-2 protein expression was inverted with significant expression in the Normal and IBS groups and reduced levels in IBD and CRC. PPARγ mRNA expression was unchanged in IBD and CRC but was significantly elevated in the IBS. IL-17A mRNA was significantly reduced in IBS and CRC but unchanged in IBD. There were no differences in all parameters tested in the Normal and IBS groups.

CONCLUSION

β-catenin is confirmed as a major driver of colorectal carcinogenesis but is controlled by many more players other than APC. Elevated levels of PPARγ may have an anticarcinogenic effect. The role of COX-2 expression, especially its posttranscriptional regulation in colorectal cancer, needs further elucidation.

A Novel Prebiotic Blend Product Prevents Irritable Bowel Syndrome in Mice by Improving Gut Microbiota and Modulating Immune Response

Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder yet it still lacks effective prevention therapies. The aim of this study is to determine whether a novel prebiotic blend (PB) composed of fructo-oligosaccharide (FOS), galactooligosaccharide (GOS), inulin and anthocyanins could be effective in preventing the development of IBS. We explored the possible mechanisms both in animal and in cells. Post-infectious IBS models in C57BL/6 mice were established and were pretreated with the PB, PB and probiotic strains 8 weeks in advance of infection. Eight weeks after infection, intestinal tissues were collected for assessing histomorphology, visceral sensitivity, barrier function, pro-inflammatory cytokines expression and proteomics analysis. Fecal samples were also collected for microbiota analysis. The pro-inflammatory cytokines expression in Caco-2 cells were evaluated after co-incubation with PB and Salmonella typhimurium 14028. The results showed that PB significantly decreased the pro-inflammatory cytokines both in infected Caco-2 cells and PI-IBS models. The loss of body weight, decreased expression of tight junction protein Occludin (OCLN), and changes of the microbiota composition induced by infections could be greatly improved by PB intervention (p < 0.05). The proteomics analysis revealed that this function was associated with Peroxisome proliferator-activated receptor (PPAR)γ pathway.

PPAR-γ Agonists and Their Role in Primary Cicatricial Alopecia

Peroxisome proliferator-activated receptor γ (PPAR-γ) is a ligand-activated nuclear receptor that regulates the transcription of various genes. PPAR-γ plays roles in lipid homeostasis, sebocyte maturation, and peroxisome biogenesis and has shown anti-inflammatory effects. PPAR-γ is highly expressed in human sebaceous glands. Disruption of PPAR-γ is believed to be one of the mechanisms of primary cicatricial alopecia (PCA) pathogenesis, causing pilosebaceous dysfunction leading to follicular inflammation. In this review article, we discuss the pathogenesis of PCA with a focus on PPAR-γ involvement in pathogenesis of lichen planopilaris (LPP), the most common lymphocytic form of PCA. We also discuss clinical trials utilizing PPAR-agonists in PCA treatment.

Proteome and phosphoproteome analysis of commensally induced dendritic cell maturation states

Dendritic cells (DCs) can shape the immune system towards an inflammatory or tolerant state depending on the bacterial antigens and the environment they encounter. In this study we provide a proteomic catalogue of differentially expressed proteins between distinct DC maturation states, brought about by bacteria that differ in their endotoxicity. To achieve this, we have performed proteomics and phosphoproteomics on murine DC cultures. Symbiont and pathobiont bacteria were used to direct dendritic cells into a semi-mature and fully-mature state, respectively. The comparison of semi-mature and fully-mature DCs revealed differential expression in 103 proteins and differential phosphorylation in 118 phosphosites, including major regulatory factors of central immune processes. Our analyses predict that these differences are mediated by upstream elements such as SOCS1, IRF3, ABCA1, TLR4, and PTGER4. Our analyses indicate that the symbiont bacterial strain affects DC proteome in a distinct way, by downregulating inflammatory proteins and activating anti-inflammatory upstream regulators. Biological significance In this study we have investigated the responses of immune cells to distinct bacterial stimuli. We have used the symbiont bacterial strain B. vulgatus and the pathobiont E. coli strain to stimulate cultured primary dendritic cells and performed a shotgun proteome analysis to investigate the protein expression and phosphorylation level differences on a genome level. We have observed expression and phosphorylation level differences in key immune regulators, transcription factors and signal transducers. Moreover, our subsequent bioinformatics analysis indicated regulation at several signaling pathways such as PPAR signaling, LXR/RXR activation and glucocorticoid signaling pathways, which are not studied in detail in an inflammation and DC maturation context. Our phosphoproteome analysis showed differential phosphorylation in 118 phosphosites including those belonging to epigenetic regulators, transcription factors and major cell cycle regulators. We anticipate that our study will facilitate further investigation of immune cell proteomes under different inflammatory and non-inflammatory conditions.

Dysplasia and colorectal cancer surveillance in inflammatory bowel disease

Inflammatory bowel disease (IBD) patients are at an increased risk of developing colorectal cancer (CRC), a devastating complication of which intestinal dysplasia is the precursor. Considerable progress has been made to determine CRC risk in IBD, identification & management of dysplasia and preventative methods. Traditionally, surveillance colonoscopies with random colonic biopsies was used. However recent data suggests that chromoendoscopy is a better method of surveillance. Using 5-aminosalicylic acid agents primarily for chemoprevention is an ongoing debate however, when prescribed along with other strategies to control inflammation, their use is considered of benefit. This review presents current understanding of risk factors of neoplasia focusing on dysplasia and preventive strategies. Areas covered: PubMed search was done using key words to assess current evidence. Along with genetics, risk factors, strategies that modify the risk of dysplasia, and CRC in IBD are discussed in detail. Expert commentary: The role of our strategies in modifying CRC risk needs further assessment. Future research should aim to fill knowledge gaps such as high quality evidence for Chromoendoscopy and development of molecular markers for dysplasia detection. Our ultimate goal would be to eliminate CRC and is possible by better understanding of key pathogenic mechanisms in IBD.