Th17 Cell-Derived Amphiregulin Promotes Colitis-Associated Intestinal Fibrosis Through Activation of mTOR and MEK in Intestinal Myofibroblasts

MK2 Inhibition in CD4+ T Cells Protects Against IFNγ and IL-17A, Chronic Inflammation, and Fibrosis in Inflammatory Bowel Disease Models

BACKGROUND

CD4+ T cells contribute to chronic inflammation and fibrosis in inflammatory bowel disease (IBD), but the cellular mechanisms remain elusive. We have found that the mitogen-activated protein kinase 2 (MK2) pathway plays a major role in inflammation and overall pathology in IBD. Thus, here, we examined the role of MK2 in regulating CD4+ T cell responses in IBD models.

METHODS

Interleukin-10 (IL-10) knockout (KO) mice treated with MK2 inhibitors (MK2i) and CD4-specific MK2 knockdown mice treated with chronic dextran sodium sulfate (DSS) treatments were used to examine inflammation and fibrosis by multiplex array, gene expression, flow cytometry, and histology. Human tissues were treated with MK2i to examine Th1 and Th17 markers.

RESULTS

IL-10 KO mice treated with MK2i therapeutically showed significantly reduced interferon gamma (IFNγ) and interleukin-17A (IL-17A) and a significantly reduced number of IFNγ+ and IL-17A+ producing CD4+ T cells by flow cytometry. To investigate the direct role of MK2 in CD4+ T cells during IBD, we utilized CD4-specific MK2 knockdown mice in chronic DSS colitis. A decrease in colonic inflammation, IFNγ and IL-17,pro-fibrotic genes, and extracellular matrix deposition was observed in mice with MK2 knockdown in CD4+ T cells compared to control mice. Additionally, IL-17A and IFNγ directly regulated the expression of fibrosis genes in colon tissues.

CONCLUSIONS

The MK2 pathway regulates inflammatory CD4+ T cells and fibrosis in IBD models and is a potential therapeutic target.

Inflammatory monocyte-derived amphiregulin mediates intestinal fibrosis in Crohn's disease by activating PI3K/AKT

Intestinal fibrosis is one of the most threatening complications of Crohn's disease (CD). Although our previous study identified the profibrotic role of amphiregulin (AREG) in intestinal fibrosis, the underlying molecular mechanisms remain poorly understood. This study aimed to elucidate the mechanisms by which AREG mediates intestinal fibrosis. Specimens from stenotic and non-stenotic lesions in CD patients were collected, alongside normal specimens from individuals with intestinal diverticula, for the assessment of AREG levels. A dextran sulfate sodium (DSS)-induced chronic colitis model was established in wild type (WT) and Areg-knockout (Areg-/-) mice. RNA-sequencing (RNA-seq) was performed on human intestinal fibroblasts (HIFs) to elucidate the underlying mechanisms. Additionally, the single-cell RNA-seq data of full-thickness CD, obtained from Prof. Rieder, was reanalyzed. Elevated levels of AREG were detected at stenotic sites in patients with CD. Areg-/- colitis mice exhibited decreased intestinal fibrosis. AREG enhanced the activation and proliferation of HIFs by activating the PI3K/AKT pathway. The inhibitor of the PI3K/AKT pathway effectively suppressed AREG-induced activation and proliferation of HIFs and attenuated colitis-associated fibrosis in mice. In stricturing CD, inflammatory monocytes exhibited higher AREG levels, contributing to the activation and proliferation of intestinal fibroblasts. Adoptive transfer of Ly6chi inflammatory monocytes from WT but not Areg-/- mice exacerbated intestinal fibrosis in DSS-induced colitis mice. These findings reveal that inflammatory monocytes derived-AREG promotes intestinal fibrosis in experimental colitis and CD patients by promoting intestinal fibroblasts activation and proliferation through the PI3K/AKT pathway. Inflammatory monocytes serve as the primary source of AREG in stricturing CD, critically mediating fibroblast-related fibrotic progression in an AREG-dependent manner. Therefore, AREG, the PI3K/AKT pathway and inflammatory monocytes may serve as potential therapeutic targets for intestinal fibrosis in CD.

Therapeutic potential of Janus kinase inhibitors for the management of fibrosis in inflammatory bowel disease

Intestinal fibrosis in inflammatory bowel disease (IBD) is caused by uncontrolled accumulation of extracellular matrix deposited by fibroblasts. This may result in stricture formation, especially in Crohn's disease. Since there are no anti-fibrotic drugs available, endoscopic or surgical interventions are the only options to treat intestinal strictures. The Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway plays a crucial role in intestinal homeostasis and inflammation. JAK inhibition represents a relatively novel therapeutic strategy in IBD by simultaneously blocking multiple cytokines across various inflammatory pathways. Interestingly, JAK inhibitors extend their benefits beyond anti-inflammatory effects, as they have been shown to interfere with fibrotic processes in various diseases, including IBD. We here summarize the current understanding of the role of the JAK-STAT pathway in the pathogenesis of intestinal fibrosis and the application of JAK inhibitors for IBD. In addition, we discuss the use of JAK inhibitors in other fibrotic-related diseases to postulate how these agents might be applied for future treatment of intestinal fibrosis.

The fibroinflammatory response in cancer

Fibroinflammation refers to the highly integrated fibrogenic and inflammatory responses mediated by the concerted function of fibroblasts and innate immune cells in response to tissue perturbation. This process underlies the desmoplastic remodelling of the tumour microenvironment and thus plays an important role in tumour initiation, growth and metastasis. More specifically, fibroinflammation alters the biochemical and biomechanical signalling in malignant cells to promote their proliferation and survival and further supports an immunosuppressive microenvironment by polarizing the immune status of tumours. Additionally, the presence of fibroinflammation is often associated with therapeutic resistance. As such, there is increasing interest in targeting this process to normalize the tumour microenvironment and thus enhance the treatment of solid tumours. Herein, we review advances made in unravelling the complexity of cancer-associated fibroinflammation that can inform the rational design of therapies targeting this.

The Role of Gut Microbiota on Intestinal Fibrosis in Inflammatory Bowel Disease and Traditional Chinese Medicine Intervention

Inflammatory bowel disease (IBD) is a chronic, relapsing inflammatory disorder of the intestine, frequently complicated by intestinal fibrosis. As fibrosis progresses, it can result in luminal stricture and compromised intestinal function, significantly diminishing patients' quality of life. Emerging evidence suggests that gut microbiota and their metabolites contribute to the pathogenesis of IBD-associated intestinal fibrosis by influencing inflammation and modulating immune responses. This review systematically explores the mechanistic link between gut microbiota and intestinal fibrosis in IBD and evaluates the therapeutic potential of traditional Chinese medicine (TCM) interventions. Relevant studies were retrieved from PubMed, Web of Science, Embase, Scopus, CNKI, Wanfang, and VIP databases. Findings indicate that TCM, including Chinese herbal prescriptions and bioactive constituents, can modulate gut microbiota composition and microbial metabolites, ultimately alleviating intestinal fibrosis through anti-inflammatory, immunemodulatory, and anti-fibrotic mechanisms. These insights highlight the potential of TCM as a promising strategy for targeting gut microbiota in the management of IBD-associated fibrosis.

Intestinal fibrosis associated with inflammatory bowel disease: Known and unknown

ABSTRACT

Intestinal fibrosis is a major complication of inflammatory bowel disease (IBD), leading to a high incidence of surgical interventions and significant disability. Despite its clinical relevance, no targeted pharmacological therapies are currently available. This review aims to explore the underlying mechanisms driving intestinal fibrosis and address unresolved scientific questions, offering insights into potential future therapeutic strategies. We conducted a literature review using data from PubMed up to October 2024, focusing on studies related to IBD and fibrosis. Intestinal fibrosis results from a complex network involving stromal cells, immune cells, epithelial cells, and the gut microbiota. Chronic inflammation, driven by factors such as dysbiosis, epithelial injury, and immune activation, leads to the production of cytokines like interleukin (IL)-1β, IL-17, and transforming growth factor (TGF)-β. These mediators activate various stromal cell populations, including fibroblasts, pericytes, and smooth muscle cells. The activated stromal cells secrete excessive extracellular matrix components, thereby promoting fibrosis. Additionally, stromal cells influence the immune microenvironment through cytokine production. Future research would focus on elucidating the temporal and spatial relationships between immune cell-driven inflammation and stromal cell-mediated fibrosis. Additionally, investigations are needed to clarify the differentiation origins of excessive extracellular matrix-producing cells, particularly fibroblast activation protein (FAP) + fibroblasts, in the context of intestinal fibrosis. In conclusion, aberrant stromal cell activation, triggered by upstream immune signals, is a key mechanism underlying intestinal fibrosis. Further investigations into immune-stromal cell interactions and stromal cell activation are essential for the development of therapeutic strategies to prevent, alleviate, and potentially reverse fibrosis.

Treg and intestinal myofibroblasts-derived Amphiregulin induced by TGF-β mediates intestinal fibrosis in Crohn's disease

BACKGROUND

Intestinal fibrosis is a serious complication of Crohn's disease (CD), often resulting from chronic inflammation. However, the precise mechanisms through which inflammation induces intestinal fibrosis remain inadequately elucidated.

METHODS

A comprehensive single-cell atlas of full-thickness CD, provided by Dr. Florian Rieder, was subjected to reanalysis. Our study used a DSS-induced chronic colitis model in both wild-type (WT) and Areg-/- mice. Additionally, a CD45RBhi CD4+ T cell adoptive transfer model involving WT and Areg-/- Treg cells (Tregs) was used. The expressions of AREG in CD with or without intestinal fibrosis, Tregs and human intestinal myofibroblasts (MFs) were determined. The effect of AREG on proliferation/migration/activation in human intestinal MFs was determined.

RESULTS

Several types of cells were differentially expressed between stricture and non-stricture CD. Among T cells, Tregs accounted for a larger proportion and were significantly increased in stenotic tissues of stricture CD. Although DSS-induced colitis was more severe in Areg-/- mice, which developed less severe intestinal fibrosis compared with WT mice. The transfer of Areg-/- Tregs resulted in less severe fibrosis in Rag-/- mice than WT Tregs. Moreover, TGF-β stimulated AREG expression in Tregs and human intestinal MFs via activation of Smad3.

CONCLUSION

These findings demonstrated that AREG derived from Tregs and human intestinal MFs, induced by TGF-β, amplifies intestinal fibrotic reactions in experimental colitis as well as in human CD patients. Thus, the TGF-β-Smad3-AREG pathway could be a potential therapeutic target for treating fibrosis in CD.

Gut microbiota and intestinal immunity interaction in ulcerative colitis and its application in treatment

Ulcerative colitis (UC) is a chronic, non-specific inflammatory bowel disease characterized by inflammation and injury of the colonic mucosa, exhibiting an increasing global incidence. Although research into UC pathogenesis is ongoing, the precise mechanisms remain to be fully elucidated. Studies indicate that UC development results from a complex interplay of factors, including genetic predisposition, environmental exposures, gut microbial dysbiosis, and immune dysregulation. Specifically, UC pathogenesis involves aberrant immune responses triggered by interactions between the host and gut microbiota. A complex, dynamic relationship exists between the microbial community and the host immune system throughout UC pathogenesis. Accumulating evidence suggests that changes in microbiota composition significantly impact gut immunity. This review will examine the intricate balance between the gut microbiota and mucosal immunity in UC progression and discuss potential therapeutic applications, providing a reference for further clinical treatment of this patient population.

The multi-organ landscape of B cells highlights dysregulated memory B cell responses in Crohn's disease

Crohn's disease (CD) is a prevalent type of inflammatory bowel disease (IBD) with dysregulated antibody responses. However, there is a lack of comprehensive analysis of B cell responses in CD. Here, we collected B cells from the small intestine, colon and blood of CD patients and control subjects. Through the coupled analysis of transcriptome and immunoglobulin (Ig) gene in individual cells, we characterized the cellular composition, transcriptome and Ig clonotype in different B cell subtypes. We observed shared disruptions in plasma cell (PC) responses between different IBD subtypes. We revealed heterogeneity in memory B cells (MBCs) and showed a positive correlation between gut resident-like MBCs and disease severity. Furthermore, our clonotype analysis demonstrated an increased direct differentiation of MBCs into PCs in CD patients. Overall, this study demonstrates significantly altered B cell responses associated with chronic inflammation during CD and highlights the potential role of mucosal MBCs in CD pathogenesis.

The positive correlation between amphiregulin and insulin resistance

Objective

Obesity and insulin resistance carry a high risk of progressing to type 2 diabetes mellitus. A lot of evidence has tightly associated insulin resistance with chronic inflammation. Besides, it has been reported that the activation of amphiregulin epidermal growth factor receptor pathways is involved in chronic inflammation. The aim of this study was to evaluate the relationship between insulin resistance and amphiregulin.

Methods

Data from 203 volunteers were collected from November 2020 to June 2023 visiting the Affiliated Suzhou Hospital of Nanjing Medical University, Jiangsu, China. The serum levels of amphiregulin and diabetes-related parameters were measured in all participants. The correlation analysis and multiple stepwise regression of amphiregulin and some diabetes indicators were performed in all groups.

Results

The concentrations of amphiregulin were 143.29, 163.29, 158.92, 171.89 and 155.03 pg/mL in the normal, obesity, nonobese diabetes, obese diabetes and obese diabetes after therapy groups (P < 0.01), respectively, and the homeostasis model assessment index were 1.6, 4.01, 3.93, 6.67 and 3.4, respectively (P < 0.01). Moreover, amphiregulin positively correlated with the homeostasis model assessment index in each separated group and the total sample (r = 0.644, P < 0.01). Meanwhile, the regression analysis showed a strong, positive association between amphiregulin and the homeostasis model assessment index (P < 0.01). More importantly, this correlation remained after obese diabetes patients were treated with drugs to relieve insulin resistance.

Conclusion

Amphiregulin is upregulated in obese individuals than in normal size people, whether diabetic or not, and positively correlates with the homeostasis model assessment index, suggesting early signs of insulin resistance and abnormal glucose metabolism.

Mesenteric adipose-derived exosomal TINAGL1 enhances intestinal fibrosis in Crohn's Disease via SMAD4

INTRODUCTION

Crohn's Disease (CD) is a chronic inflammatory condition characterized by intestinal fibrosis, severely impacting patient quality of life. The molecular mechanisms driving this fibrosis remain inadequately understood. Recent evidence implicates mesenteric adipose tissue (MAT) in CD pathogenesis, particularly through its exosome secretion, which may influence fibrogenic pathways. Understanding the role of MAT-derived exosomes is crucial for unraveling these molecular processes.

OBJECTIVES

This study aims to elucidate the role of MAT-derived exosomes in CD-related intestinal fibrosis. We focus on investigating their molecular composition and the potential impact on fibrosis progression, with an emphasis on identifying novel therapeutic targets.

METHODS

We induced chronic intestinal inflammation in mice using dinitrobenzene sulfonic acid (DNBS), simulating CD-like fibrosis. Exosomes were isolated from DNBS-treated mice (MG) and normal controls (NG) for characterization using electron microscopy and proteomic analysis. Additionally, human colonic fibroblasts were exposed to exosomes from CD patients and healthy individuals, with subsequent assessment of fibrogenesis through proteomic and RNA sequencing analyses.

RESULTS

Proteomic analyses revealed a significant activation of the TGF-β signaling pathway in MG-treated mice compared to controls, correlating with enhanced intestinal fibrosis. In vitro experiments demonstrated that colonic fibroblasts exposed to CD patient-derived exosomes exhibited increased fibrogenic activity. Protein docking and co-immunoprecipitation studies suggested a critical interaction between TINAGL1 and SMAD4, enhancing fibrosis. Importantly, in vivo experiments corroborated that recombinant TINAGL1 protein exacerbated DNBS-induced intestinal fibrosis.

CONCLUSION

Our findings highlight the pivotal role of MAT-derived exosomes, particularly those carrying TINAGL1, in the progression of intestinal fibrosis in CD. The involvement of the TGF-β signaling pathway, especially the SMAD4 protein, offers new insights into the molecular mechanisms of CD-related fibrosis and presents potential targets for therapeutic intervention.

Rapamycin protects glucocorticoid-induced glaucoma model mice against trabecular meshwork fibrosis by suppressing mTORC1/2 signaling

Systemic or local use of glucocorticoids (GCs) can induce pathological elevation of intraocular pressure (IOP), potentially leading to permanent visual loss. Previous studies have demonstrated that rapamycin (Rapa) inhibits the activation of retinal glial cells (RGC) and the production of neuroinflammation, achieving neuroprotective goals. However, there has been little research on the effect of Rapa on the trabecular meshwork (TM). This study aimed to investigate the protective effect and potential mechanism of Rapa in a glucocorticoid-induced glaucoma (GIG) model. Our findings indicate that Rapa significantly inhibited the IOP increase induced by dexamethasone acetate (Dex-Ac) and improved TM fibrosis and RGC damage. In cultured human trabecular meshwork cells (HTMCs) treated with dexamethasone (Dex) and Rapa under different conditions revealed that Rapa inhibits Dex-induced HTMC fibrosis and cytoskeletal changes. This effect may result from the specific suppression of the mechanistic target of rapamycin complex 1 (mTORC1) pathway by Rapa, which reduces abnormal extracellular matrix (ECM) deposition. Alternatively, the improvement in cytoskeleton entanglement might be due to the inhibition of the mechanistic target of rapamycin complex 2 (mTORC2) pathway. These two potential mechanisms may collectively contribute to the protective effects of Rapa in GIG. This study provides a new theoretical basis for using of Rapa in the treatment of GIG.

Oral submucous fibrosis: pathogenesis and therapeutic approaches

Oral submucous fibrosis (OSF), characterized by excessive deposition of extracellular matrix (ECM) that causes oral mucosal tissue sclerosis, and even cancer transformation, is a chronic, progressive fibrosis disease. However, despite some advancements in recent years, no targeted antifibrotic strategies for OSF have been approved; likely because the complicated mechanisms that initiate and drive fibrosis remain to be determined. In this review, we briefly introduce the epidemiology and etiology of OSF. Then, we highlight how cell-intrinsic changes in significant structural cells can drive fibrotic response by regulating biological behaviors, secretion function, and activation of ECM-producing myofibroblasts. In addition, we also discuss the role of innate and adaptive immune cells and how they contribute to the pathogenesis of OSF. Finally, we summarize strategies to interrupt key mechanisms that cause OSF, including modulation of the ECM, inhibition of inflammation, improvement of vascular disturbance. This review will provide potential routes for developing novel anti-OSF therapeutics.

Myeloid-Derived Suppressor Cell Accumulation Drives Intestinal Fibrosis through mCCL6/hCCL15 Chemokine-Mediated Fibroblast Activation

Intestinal fibrosis, a severe complication of Crohn's disease (CD), is linked to chronic inflammation, but the precise mechanism by which immune-driven intestinal inflammation leads to fibrosis development is not fully understood. This study investigates the role of myeloid-derived suppressor cells (MDSCs) in intestinal fibrosis in CD patients and a 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced mouse model. Elevated MDSCs are observed in inflamed intestinal tissues prior to fibrosis and their sustained presence in fibrotic tissues of both CD patients and murine models. Depletion of MDSCs significantly reduces fibrosis, highlighting their key role in the fibrotic process. Mechanistically, MDSC-derived mCCL6 activates fibroblasts via the CCR1-MAPK signaling, and interventions targeting this axis, including neutralizing antibodies, a CCR1 antagonist, or fibroblast-specific Ccr1 knockout mice reduce fibrosis. In CD patients with stenosis, human CCL15, analogous to mCCL6, is found to be elevated in MDSCs and activated fibroblasts. Additionally, CXCR2 and CCR2 ligands are identified as key mediators of MDSC recruitment in intestinal fibrosis. Blocking MDSC recruitment with CXCR2 and CCR2 antagonists alleviates intestinal fibrosis. These findings suggest that strategies targeting MDSC recruitment and mCCL6/hCCL15 signaling could offer therapeutic benefits for intestinal fibrosis.

SAA3 deficiency exacerbates intestinal fibrosis in DSS-induced IBD mouse model

Intestinal fibrosis, as a late-stage complication of inflammatory bowel disease (IBD), leads to bowel obstruction and requires surgical intervention, significantly lowering the quality of life of affected patients. SAA3, a highly conserved member of the serum amyloid A (SAA) apolipoprotein family in mice, is synthesized primarily as an acute phase reactant in response to infection, inflammation and trauma. An increasing number of evidence suggests that SAA3 exerts a vital role in the fibrotic process, even though the underlying mechanisms are not yet fully comprehended. This study utilized dextran sulfate sodium (DSS) to establish an IBD mouse model and observed that the SAA3-deficient mice exhibited more severe intestinal fibrosis. Our results further indicated that SAA3 genetic disruption in fibroblasts enhanced cell activation to myofibroblasts through HSPB1/NF-κB/TGF-β1/Smads signaling cascade, exacerbating the pathological phenotype of intestinal fibrosis. Collectively, our results shed novel lights on regulating SAA3 in intestinal fibrosis and indicate the potential to develop therapeutic strategies for IBD patients.

Single-cell RNA-seq reveals immune cell heterogeneity and increased Th17 cells in human fibrotic skin diseases

Background

Fibrotic skin disease represents a major global healthcare burden, characterized by fibroblast hyperproliferation and excessive accumulation of extracellular matrix components. The immune cells are postulated to exert a pivotal role in the development of fibrotic skin disease. Single-cell RNA sequencing has been used to explore the composition and functionality of immune cells present in fibrotic skin diseases. However, these studies detected the gene expression of all cells in fibrotic skin diseases and did not enrich immune cells. Thus, the precise immune cell atlas in fibrotic skin diseases remains unknown. In this study, we plan to investigate the intricate cellular landscape of immune cells in keloid, a paradigm of fibrotic skin diseases.

Methods

CD45+ immune cells were enriched by fluorescence-activated cell sorting. Single-cell RNA sequencing was used to analyze the cellular landscape of immune cells in keloid and normal scar tissues. Ki-67 staining, a scratch experiment, real-time PCR, and Western blotting were used to explore the effect of the Th17 cell supernatant on keloid fibroblasts.

Results

Our findings revealed the intricate cellular landscape of immune cells in fibrotic skin diseases. We found that the percentage of Th17 cells was significantly increased in keloids compared to normal scars. All the subclusters of macrophages and dendritic cells (DCs) showed similar proportions between keloid samples and normal scar samples. However, upregulated genes in keloid M1 macrophages, M2 macrophages, and cDC2 are associated with the MHC class II protein complex assembly and antigen assembly, indicating that macrophages and cDC2 are active in keloids. Functional studies suggested that the supernatant of Th17 cells could promote proliferation, collagen expression, and migration of keloid fibroblasts through interleukin 17A. Importantly, increased Th17 cells are also found in other fibrotic skin diseases, such as hypertrophic scars and scleroderma, suggesting this represents a broad mechanism for skin fibrosis.

Conclusion

In summary, we built a single-cell atlas of fibrotic skin diseases in this study. In addition, we explored the function of Th17 cell-fibroblast interaction in skin fibrosis. These findings will help to understand fibrotic skin disease pathogenesis in depth and identify potential targets for fibrotic skin disease treatment.

Adipose-derived stem cell exosomes attenuates myofibroblast transformation via inhibiting autophagy through TGF-β/Smad2 axis in oral submucosal fibrosis

Oral submucous fibrosis (OSF) is a precancerous condition that poses substantial health risks. OSF is mainly caused by betel nut chewing behavior, but its pathogenesis is still unclear and there is no effective treatment strategy. The transformation of fibroblasts to myofibroblast is the key pathological change in the development of OSF. We isolated fibroblasts from human oral mucosa and induced them into myofibroblasts by arecoline, during which autophagy was significantly activated. Here, we found that adipose-derived stem cell exosomes (ADSCs-EXO) could inhibit autophagy to regulate myofibroblast phenotype, and transcriptome sequencing analysis suggested that this process is closely related to the TGF-β pathway. The interplay between autophagy and TGF-β pathway was examined through modulation the two with autophagy activators and inhibitors, TGF-β receptor activators and inhibitors. Results showed that in vitro, the TGF-β/Smad2 pathway augmented autophagy and promoted myofibroblast transformation. The transcriptome information of ADSCs-EXO showed that it contains a large number of miRNAs. Among them, miR-125a-5p could target Smad2. In vivo, injection of ADSCs-EXO alleviated OSF in mice, during which TGF-β and autophagy signals were inhibited. We suggested that ADSCs-EXO could inhibit myofibroblast transformation via inhibiting autophagy through TGF-β/Smad2 axis in OSF, providing new insights for autophagy-based intervention strategies.

Th9 and Th17 Cells in Human Ulcerative Colitis-Associated Dysplastic Lesions

Background

Inflammation is the most important deriving force for the development of colitis-associated colorectal cancer (CAC) through the Inflammation-Pretumor dysplasia-CAC sequence. T helper (Th) subsets Th9 and Th17 cells can potentially stimulate inflammation in the ulcerative colitis (UC). Therefore, Th9 and Th17 cells may play a promoting role in the colitis-associated dysplasia (CAD).

Methods

Using immunohistochemistry (IHC), we evaluated the presentation patterns and densities of T lymphocytes, Th9 and Th17 cells in human UC and CAD tissues.

Results

A general increasing trend of CD3-positive T lymphocytes, P.U.1-positive Th9 and interleukin (IL)-17A-positive Th17 cells was illustrated throughout the normal-UC-CAD sequence, IHC images showed that these cells were very prominent in the lamina propria, and some cells were also observed in the epithelium in the CAD tissues. Density analysis revealed that numbers of Th9 and Th17 cells were progressively increased in the CAD tissues as compared with the UC and control tissues. In general, densities of Th9 and Th17 cells in the lamina propria were slightly higher in the non-adenoma-like dysplasia (NALD) tissues than that in the adenoma-like dysplasia (ALD) tissues. However, densities of neither Th9 nor Th17 cells in both the ALD and NALD subgroups were associated with the degree of dysplasia in CAD lesions.

Conclusion

Accumulated Th9 and Th17 cells contribute to the immune cellular composition in the CAD tissues and may represent the early conditional change for the Dysplasia-CAC transition.

JPH203 alleviates peritoneal fibrosis via inhibition of amino acid-mediated mTORC1 signaling

BACKGROUND AND AIMS

The mesothelial-mesenchymal transition (MMT) of mesothelial cells has been recognized as a critical process during progression of peritoneal fibrosis (PF). Despite its crucial role in amino acid transport and metabolism, the involvement of L-type amino acid transporter 1 (LAT1) and the potential therapeutic role of its inhibitor, JPH203, in fibrotic diseases remain unexplored. Considering the paucity of research on amino acid-mediated mTORC1 activation in PF, our study endeavors to elucidate the protective effects of JPH203 against PF and explore the involvement of amino acid-mediated mTORC1 signaling in this context.

METHODS

We established the transforming growth factor beta 1 (TGF-β1) induced MMT model in primary human mesothelial cells and the peritoneal dialysis fluid (PDF) induced PF model in mice. The therapeutic effects of JPH203 on PF were then examined on these two models by real-time quantitative polymerase chain reaction, western blotting, immunofluorescence staining, Masson's trichrome staining, H&E staining, picro-sirius red staining, and immunohistochemistry. The involvement of amino acid-mediated mTORC1 signaling was screened by RNA sequencing and further verified by western blotting in vitro.

RESULTS

LAT1 was significantly upregulated and JPH203 markedly attenuated fibrotic phenotype both in vitro and in vivo. RNA-seq unveiled a significant enrichment of mTOR signaling pathway in response to JPH203 treatment. Western blotting results indicated that JPH203 alleviates PF by inhibiting amino acid-mediated mTORC1 signaling, which differs from the direct inhibition observed with rapamycin.

CONCLUSION

JPH203 alleviates PF by inhibiting amino acid-mediated mTORC1 signaling.

Anti-fibrotics in inflammatory bowel diseases: Challenges and successes

Stricture formation leading to obstruction in Crohn's disease (CD) remains one of the largest unmet needs in the field of inflammatory bowel diseases (IBD). Despite this need no selective anti-stricture drug has been approved for use in CD patients. This contrasts with other fibrotic diseases, such as in the lung, liver or kidney, where multiple drug development programs crossed the starting line and two anti-fibrotics are now being approved for pulmonary fibrosis. Strictures are composed of a mix of inflammation, excessive deposition of extracellular matrix (ECM) and smooth muscle hyperplasia, likely all ultimately being responsible for the luminal narrowing driving patient symptoms. Our understanding of the pathogenesis of stricturing CD has evolved and indicates a multifactorial process involving immune and non-immune cells and their soluble mediators. This understanding has rendered target pathways for anti-stricture drug development. Significant progress was made in creating consensus definitions and tools to enable clinical trials with two clinical development programs having been conceived to date. In this chapter, we discuss stricture pathogenesis with a focus on the pathways being tested in clinical trials, and clinical trial endpoints developed for this indication.

Amphiregulin Upregulation in Visfatin-Stimulated Colorectal Cancer Cells Reduces Sensitivity to 5-Fluororacil Cytotoxicity

Colorectal cancer (CRC) has become a prevalent and deadly malignancy over the years. Drug resistance remains a major challenge in CRC treatment, significantly affecting patient survival rates. Obesity is a key risk factor for CRC development, and accumulating evidence indicates that increased secretion of adipokines, including Visfatin, under obese conditions contributes to the development of resistance in CRC to various therapeutic methods. Amphiregulin (AREG) is a member of the epidermal growth factor (EGF) family, which activates the EGF receptor (EGFR), influencing multiple tumorigenic characteristics of cancers. Abnormal expression levels of AREG in cancer cells have been associated with resistance to anti-EGFR therapy in patients. However, it remains unclear whether this abnormal expression also impacts CRC resistance to other chemotherapeutic drugs. The aim of this study is to examine whether AREG expression levels could be affected in CRC cells under Visfatin stimulation, thereby initiating the development of resistance to 5-fluororacil (5-FU). Through our results, we found that Visfatin indeed increases AREG expression, reducing the sensitivity of HCT-116 CRC cells to 5-FU cytotoxicity. Moreover, AREG upregulation is regulated by STAT3-CREB transcription factors activated by JNK1/2 and p38 signaling. This study highlights the significant role of AREG upregulation in CRC cells in initiating chemotherapeutic resistance to 5-FU under Visfatin stimulation. These findings provide a deeper understanding of drug resistance development in CRC under obese conditions and offer new insights into the correlation between an abnormal increase in AREG levels and the development of 5-FU-resistance in CRC cells, which should be considered in future clinical applications.

Pharmacological Impacts of Mucopolysacccharide Polyphosphates in the Epidermis Involves Inhibition of Amphiregulin-Mediated Signals in Keratinocytes

The epidermis, the most superficial layer of the human skin, serves a critical barrier function, protecting the body from external pathogens and allergens. Dysregulation of epidermal differentiation contributes to barrier dysfunction and has been implicated in the pathology of various dermatological diseases, including atopic dermatitis (AD). Mucopolysaccharide polysulphate (MPS) is a moisturising agent used to treat xerosis in patients with AD. However, its mechanism of action on keratinocytes, the main constituents of the epidermis, remains unclear. In this study, we investigated the effect of MPS on keratinocytes by subjecting adult human epidermal and three-dimensional cultured keratinocytes to MPS treatment, followed by transcriptome analysis. The analysis revealed that MPS treatment enhances keratinocyte differentiation and suppresses proliferation. We focused on amphiregulin (AREG), a membrane protein that belongs to the epidermal growth factor (EGF) family and possesses a heparin-binding domain, as a significant target among the genes altered by MPS. MPS exerted an inhibitory effect directly on AREG, rather than on EGF receptors or other members of the EGF family. Furthermore, AREG leads to a reduction in epidermal barrier function, whereas MPS contributes to barrier enhancement via AREG inhibition. Collectively, these findings suggest that MPS modulates barrier function through AREG inhibition, offering insights into potential therapeutic strategies for skin barrier restoration.

Intestinal Stromal Cells in the Turmoil of Inflammation and Defective Connective Tissue Remodeling in Inflammatory Bowel Disease

In steady state, intestinal subepithelial myofibroblasts form a thin layer below the basement membrane. Unlike the rest of the stromal cells in the lamina propria, they express tensile proteins, guide epithelial regeneration, and sense luminal microbiota. Upon inflammation in inflammatory bowel disease (IBD), they express activation markers, accept trophic signaling by infiltrating neutrophils and macrophages, and are activated by cytokines from helper T cells to produce a narrow spectrum of cytokines and a wider spectrum of chemokines, attract cells of innate and adaptive immunity, orchestrate inflammatory responses, and qualitatively and quantitatively modify the extracellular matrix. Thus, beyond being structural tissue components, they assume active roles in the pathogenesis of complicated IBD. Discrimination between myofibroblasts and fibroblasts may be an oversimplification in light of single-cell sequencing data unveiling the complexity of multiple phenotypes of stromal cells with distinct roles and plasticity. Spatial transcriptomics revealed distinct phenotypes by histologic localization and, more intriguingly, the assembly of mucosal neighborhoods that support spatially distinct functions. Current IBD treatments target inflammation but fail in fibrostenotic or fistulizing disease. Baseline and recent findings on stromal cells, molecules, and pathways involved in disrupted extracellular matrix homeostasis are reviewed to provide relevant pharmacologic targets.

Tertiary lymphoid structures in diseases: immune mechanisms and therapeutic advances

Tertiary lymphoid structures (TLSs) are defined as lymphoid aggregates formed in non-hematopoietic organs under pathological conditions. Similar to secondary lymphoid organs (SLOs), the formation of TLSs relies on the interaction between lymphoid tissue inducer (LTi) cells and lymphoid tissue organizer (LTo) cells, involving multiple cytokines. Heterogeneity is a distinguishing feature of TLSs, which may lead to differences in their functions. Growing evidence suggests that TLSs are associated with various diseases, such as cancers, autoimmune diseases, transplant rejection, chronic inflammation, infection, and even ageing. However, the detailed mechanisms behind these clinical associations are not yet fully understood. The mechanisms by which TLS maturation and localization affect immune function are also unclear. Therefore, it is necessary to enhance the understanding of TLS development and function at the cellular and molecular level, which may allow us to utilize them to improve the immune microenvironment. In this review, we delve into the composition, formation mechanism, associations with diseases, and potential therapeutic applications of TLSs. Furthermore, we discuss the therapeutic implications of TLSs, such as their role as markers of therapeutic response and prognosis. Finally, we summarize various methods for detecting and targeting TLSs. Overall, we provide a comprehensive understanding of TLSs and aim to develop more effective therapeutic strategies.

CD146-dependent macrophage infiltration promotes epidural fibrosis via the Erdr1/ERK/CCR2 pathway

Low back pain due to epidural fibrosis is a major complication after spine surgery. Macrophages infiltrate the wound area post laminectomy, but the role of macrophages in epidural fibrosis remains largely elusive. In a mouse model of laminectomy, macrophage depletion decreased epidural fibrosis. CD146, an adhesion molecule involved in cell migration, is expressed by macrophages. CD146-defective macrophages exhibited impaired migration, which was mediated by reduced expression of CCR2 and suppression of the MAPK/ERK signaling pathway. CD146-defective macrophages suppress the MAPK/ERK signaling pathway by increasing Erdr1. In vivo, CD146 deficiency decreased macrophage infiltration and reduced extracellular matrix deposition in wound tissues. Moreover, the anti-CD146 antibody AA98 suppressed macrophage infiltration and epidural fibrosis. Taken together, these findings demonstrated that CD146 deficiency alleviates epidural fibrosis by decreasing the migration of macrophages via the Erdr1/ERK/CCR2 pathway. Blocking CD146 and macrophage infiltration may help alleviate epidural fibrosis.

Single cell RNA-sequencing delineates CD8+ tissue resident memory T cells maintaining rejection in liver transplantation

Rationale: Understanding the immune mechanisms associated with liver transplantation (LT), particularly the involvement of tissue-resident memory T cells (TRMs), represents a significant challenge. Methods: This study employs a multi-omics approach to analyse liver transplant samples from both human (n = 17) and mouse (n = 16), utilizing single-cell RNA sequencing, bulk RNA sequencing, and immunological techniques. Results: Our findings reveal a comprehensive T cell-centric landscape in LT across human and mouse species, involving 235,116 cells. Notably, we found a substantial increase in CD8+ TRMs within rejected grafts compared to stable ones. The elevated presence of CD8+ TRMs is characterised by a distinct expression profile, featuring upregulation of tissue-residency markers (CD69, CXCR6, CD49A and CD103+/-,), immune checkpoints (PD1, CTLA4, and TIGIT), cytotoxic markers (GZMB and IFNG) and proliferative markers (PCNA and TOP2A) during rejection. Furthermore, there is a high expression of transcription factors such as EOMES and RUNX3. Functional assays and analyses of cellular communication underscore the active role of CD8+ TRMs in interacting with other tissue-resident cells, particularly Kupffer cells, especially during rejection episodes. Conclusions: These insights into the distinctive activation and interaction patterns of CD8+ TRMs suggest their potential utility as biomarkers for graft rejection, paving the way for novel therapeutic strategies aimed at enhancing graft tolerance and improving overall transplant outcomes.

Increased Activity of MAPKAPK2 within Mesenchymal Cells as a Target for Inflammation-Associated Fibrosis in Crohn's Disease

BACKGROUND

Mesenchymal stromal cells are suggested to play a critical role in Crohn's disease [CD]-associated fibrosis. MAPKAPK2 [MK2] has emerged as a potential therapeutic target to reduce inflammation in CD. However, the cell-specific pattern of phospho-MK2 activation and its role in CD-associated fibrosis are unknown. The objectives of this study were to evaluate cell-specific changes in MK2 activity between predominantly inflammatory CD vs CD with fibrotic complications and define the role of stromal cell-specific MK2 activation in CD-associated fibrosis.

METHODS

CD tissue, CD tissue-derived mesenchymal stromal cells known as myo-/fibroblasts [CD-MFs], and fibroblast-specific MK2 conditional knockout [KO] mice were used.

RESULTS

In the inflamed area of predominantly inflammatory CD, high MK2 activity was equally distributed between mesenchymal and haematopoietic cells. By contrast, in CD with fibrotic complications, high MK2 activity was mostly associated with mesenchymal stromal cells. Using ex vivo CD tissue explants and an IL-10KO murine colitis model, we demonstrated that pro-fibrotic responses are significantly reduced by treatment with the MK2 inhibitor PF-3644022. Inhibition of MK2 activity in primary cultures of CD-MFs significantly reduced basal and TGF-β1-induced profibrotic responses. Using fibroblast-specific MK2 knockout mice in chronic dextran saline sulphate colitis, we demonstrated that fibroblast intrinsic MK2 signalling is among the key processes involved in the chronic inflammation-induced profibrotic responses.

CONCLUSIONS

Our data suggest that activation of MK2 within fibroblasts contributes to the chronic inflammation-induced fibrosis in CD and that targeting MK2 has potential for the development of novel therapeutic approaches for fibrosis in CD.

Mediators of monocyte chemotaxis and matrix remodeling are associated with mortality and pulmonary fibroproliferation in patients with severe COVID-19

Acute respiratory distress syndrome (ARDS) has a fibroproliferative phase that may be followed by pulmonary fibrosis. Pulmonary fibrosis following COVID-19 pneumonia has been described at autopsy and following lung transplantation. We hypothesized that protein mediators of tissue remodeling and monocyte chemotaxis are elevated in the plasma and endotracheal aspirates of critically ill patients with COVID-19 who subsequently develop features of pulmonary fibroproliferation. We enrolled COVID-19 patients admitted to the ICU with hypoxemic respiratory failure. (n = 195). Plasma was collected within 24h of ICU admission and at 7d. In mechanically ventilated patients, endotracheal aspirates (ETA) were collected. Protein concentrations were measured by immunoassay. We tested for associations between protein concentrations and respiratory outcomes using logistic regression adjusting for age, sex, treatment with steroids, and APACHE III score. In a subset of patients who had CT scans during hospitalization (n = 75), we tested for associations between protein concentrations and radiographic features of fibroproliferation. Among the entire cohort, plasma IL-6, TNF-α, CCL2, and Amphiregulin levels were significantly associated with in-hospital mortality. In addition, higher plasma concentrations of CCL2, IL-6, TNF-α, Amphiregulin, and CXCL12 were associated with fewer ventilator-free days. We identified 20/75 patients (26%) with features of fibroproliferation. Within 24h of ICU admission, no measured plasma proteins were associated with a fibroproliferative response. However, when measured 96h-128h after admission, Amphiregulin was elevated in those that developed fibroproliferation. ETAs were not correlated with plasma measurements and did not show any association with mortality, ventilator-free days (VFDs), or fibroproliferative response. This cohort study identifies proteins of tissue remodeling and monocyte recruitment are associated with in-hospital mortality, fewer VFDs, and radiographic fibroproliferative response. Measuring changes in these proteins over time may allow for early identification of patients with severe COVID-19 at risk for fibroproliferation.

Amphiregulin-producing TH2 cells facilitate esophageal fibrosis of eosinophilic esophagitis

Background

Massive eosinophil infiltration into the esophagus is associated with subepithelial fibrosis and esophageal stricture in patients with eosinophilic esophagitis (EoE). However, the pathogenesis of esophageal fibrosis remains unclear.

Objective

We sought to elucidate the cellular and molecular mechanisms underlying the induction of esophageal fibrosis.

Methods

We established a murine model of EoE accompanied by fibrotic responses following long-term intranasal administration of house dust mite antigen. Using this murine model, we investigated the characteristics of immune cells infiltrating the fibrotic region of the inflamed esophagus using flow cytometry and histological analyses. We also analyzed the local inflammatory sites in the esophagus of patients with EoE using single-cell RNA sequencing, flow cytometry, and immunohistochemistry.

Results

Enhanced infiltration of both amphiregulin-producing and IL-5-producing TH2 cells was detected in the fibrotic area of the esophagus in mice subjected to repeated house dust mite exposure. Deletion of amphiregulin in CD4+ T cells ameliorates esophageal fibrosis. An analysis of human esophageal biopsy samples showed that the infiltration of amphiregulin-producing CD4+ T cells was higher in patients with EoE than in control patients. Furthermore, the number of infiltrated amphiregulin-producing CD4+ T cells was associated with the degree of esophageal fibrosis in patients with EoE.

Conclusions

Amphiregulin, produced by TH2 cells, contributes to esophageal fibrosis in EoE and may be a therapeutic target.

ETS translocation variant 5 (ETV5) promotes CD4+ T cell-mediated intestinal inflammation and fibrosis in inflammatory bowel diseases

E26 transformation-specific translocation variant 5 (ETV5) has been implicated in the pathogenesis of inflammatory bowel diseases (IBD). However, the exact roles of ETV5 in regulating CD4+ T cell-mediated intestinal inflammation and fibrosis formation remain unclear. Here, we reveal that ETV5 overexpression induced interleukin (IL)-9 and its transcription factor IRF4 expression in IBD CD4+ T cells under T helper type 9 (Th9) cells-polarizing conditions. The silencing of IRF4 inhibited ETV5-induced IL-9 expression. CD4+ T cell-specific ETV5 deletion ameliorated intestinal inflammation and fibrosis in trinitrobenzene sulfonic acid (TNBS)-induced experimental colitis and CD4+ T cell-transferred recombination-activating gene-1 knockout (Rag1-/-) colitis mice, characterized by less CD4+ T cell infiltration and lower fibroblast activation and collagen deposition in the colonic tissues. Furthermore, IL-9 treatment aggressive TNBS-induced intestinal fibrosis in CD4+ T cell-specific ETV5 deletion and wild-type control mice. In vitro, human intestinal fibroblasts cocultured with ETV5 overexpressed-Th9 cells expressed higher levels of collagen I and III, whereas an inclusion of anti-IL-9 antibody could reverse this effect. Ribonucleic acid sequencing analysis demonstrated that IL-9 upregulated TAF1 expression in human intestinal fibroblasts. Clinical data showed that number of α-smooth muscle actin+TAF1+ fibroblasts are higher in inflamed mucosa of patients with IBD. Importantly, TAF1 small interfering ribonucleic acid treatment suppressed IL-9-mediated profibrotic effect in vitro. These findings reveal that CD4+ T cell-derived ETV5 promotes intestinal inflammation and fibrosis through upregulating IL-9-mediated intestinal inflammatory and fibrotic response in IBD. Thus, the ETV5/IL-9 signal pathway in T cells might represent a novel therapeutic target for intestinal inflammation and fibrosis in IBD.

Intestinal strictures in Crohn's disease: An update from 2023

Crohn's disease (CD) is a chronic inflammatory disease that leads to intestinal stricture in nearly 35% of cases within 10 years of initial diagnosis. The unknown pathogenesis, lack of universally accepted criteria, and absence of an effective management approach remain unconquered challenges in structuring CD. The pathogenesis of stricturing CD involves intricate interactions between factors such as immune cell dysbiosis, fibroblast activation, and microecology imbalance. New techniques such as single-cell sequencing provide a fresh perspective. Non-invasive diagnostic tools such as serum biomarkers and novel cross-sectional imaging techniques offer a precise understanding of intestinal fibrostenosis. Here, we provide a timely and comprehensive review of the worthy advancements in intestinal strictures in 2023, aiming to dispense cutting-edge information regarding fibrosis and to build a cornerstone for researchers and clinicians to make greater progress in the field of intestinal strictures.

Preventing fibrosis in IBD: update on immune pathways and clinical strategies

INTRODUCTION

Intestinal fibrosis is a common and serious complication of inflammatory bowel diseases (IBD) driving stricture formation in Crohn's disease patients and leading to submucosal damage in ulcerative colitis. Recent studies provided novel insights into the role of immune and nonimmune components in the pathogenesis of intestinal fibrosis. Those new findings may accelerate the development of anti-fibrotic treatment in IBD patients.

AREAS COVERED

This review is designed to cover the recent progress in mechanistic research and therapeutic developments on intestinal fibrosis in IBD patients, including new cell clusters, cytokines, proteins, microbiota, creeping fat, and anti-fibrotic therapies.

EXPERT OPINION

Due to the previously existing major obstacle of missing consensus on stricture definitions and the absence of clinical trial endpoints, testing of drugs with an anti-fibrotic mechanism is just starting in stricturing Crohn's disease (CD). A biomarker to stratify CD patients at diagnosis without any complications into at-risk populations for future strictures would be highly desirable. Further investigations are needed to identify novel mechanisms of fibrogenesis in the intestine that are targetable and ideally gut specific.

The role of the CXCR6/CXCL16 axis in the pathogenesis of fibrotic disease

CXC chemokine receptor 6 (CXCR6), a seven-transmembrane domain G-protein-coupled receptor, plays a pivotal regulatory role in inflammation and tissue damage through its interaction with CXC chemokine ligand 16 (CXCL16). This axis is implicated in the pathogenesis of various fibrotic diseases and correlates with clinical parameters that indicate disease severity, activity, and prognosis in organ fibrosis, including afflictions of the liver, kidney, lung, cardiovascular system, skin, and intestines. Soluble CXCL16 (sCXCL16) serves as a chemokine, facilitating the migration and recruitment of CXCR6-expressing cells, while membrane-bound CXCL16 (mCXCL16) functions as a transmembrane protein with adhesion properties, facilitating intercellular interactions by binding to CXCR6. The CXCR6/CXCL16 axis is established to regulate the cycle of damage and repair during chronic inflammation, either through modulating immune cell-mediated intercellular communication or by independently influencing fibroblast homing, proliferation, and activation, with each pathway potentially culminating in the onset and progression of fibrotic diseases. However, clinically exploiting the targeting of the CXCR6/CXCL16 axis requires further elucidation of the intricate chemokine interactions within fibrosis pathogenesis. This review explores the biology of CXCR6/CXCL16, its multifaceted effects contributing to fibrosis in various organs, and the prospective clinical implications of these insights.

Ketogenic Diet Protects from Experimental Colitis in a Mouse Model Regardless of Dietary Fat Source

While ketogenic diets (KDs) may have potential as adjunct treatments for gastrointestinal diseases, there is little knowledge on how the fat source of these diets impacts intestinal health. The objective of this study was to investigate how the source of dietary fat of KD influences experimental colitis. We fed nine-week-old male C57BL/6J mice (n = 36) with a low-fat control diet or KD high either in saturated fatty acids (SFA-KD) or polyunsaturated linoleic acid (LA-KD) for four weeks and then induced colitis with dextran sodium sulfate (DSS). To compare the diets, we analyzed macroscopic and histological changes in the colon, intestinal permeability to fluorescein isothiocyanate-dextran (FITC-dextran), and the colonic expression of tight junction proteins and inflammatory markers. While the effects were more pronounced with LA-KD, both KDs markedly alleviated DSS-induced histological lesions. LA-KD prevented inflammation-related weight loss and the shortening of the colon, as well as preserved Il1b and Tnf expression at a healthy level. Despite no significant between-group differences in permeability to FITC-dextran, LA-KD mitigated changes in tight junction protein expression. Thus, KDs may have preventive potential against intestinal inflammation, with the level of the effect being dependent on the dietary fat source.

TH17 cell: a double-edged sword in the development of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic nonspecific inflammatory disease of the gastrointestinal tract, and its pathogenesis has not been fully understood. Extensive dysregulation of the intestinal mucosal immune system is critical in the development and progression of IBD. T helper (Th) 17 cells have the characteristics of plasticity. They can transdifferentiate into subpopulations with different functions in response to different factors in the surrounding environment, thus taking on different roles in regulating the intestinal immune responses. In this review, we will focus on the plasticity of Th17 cells as well as the function of Th17 cells and their related cytokines in IBD. We will summarize their pathogenic and protective roles in IBD under different conditions, respectively, hoping to further deepen the understanding of the pathological mechanisms underlying IBD and provide insights for future treatment.

Current Approach to Risk Factors and Biomarkers of Intestinal Fibrosis in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), especially Crohn's disease (CD), characterized by a chronic inflammatory process and progressive intestinal tissue damage, leads to the unrestrained proliferation of mesenchymal cells and the development of bowel strictures. Complications induced by fibrosis are related to high rates of morbidity and mortality and lead to a substantial number of hospitalizations and surgical procedures, generating high healthcare costs. The development of easily obtained, reliable fibrogenesis biomarkers is essential to provide an important complementary tool to existing diagnostic and prognostic methods in IBD management, guiding decisions on the intensification of pharmacotherapy, proceeding to surgical methods of treatment and monitoring the efficacy of anti-fibrotic therapy in the future. The most promising potential markers of fibrosis include cartilage oligomeric matrix protein (COMP), hepatocyte growth factor activator (HGFA), and fibronectin isoform- extra domain A (ED-A), as well as antibodies against granulocyte macrophage colony-stimulating factor (GM-CSF Ab), cathelicidin (LL-37), or circulatory miRNAs: miR-19a-3p and miR-19b-3p. This review summarizes the role of genetic predisposition, and risk factors and serological markers potentially contributing to the pathophysiology of fibrotic strictures in the course of IBD.

Intestinal Inflammation and Regeneration-Interdigitating Processes Controlled by Dietary Lipids in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a disease of chronic inflammatory conditions of the intestinal tract due to disturbance of the inflammation and immune system. Symptoms of IBD include abdominal pain, diarrhea, bleeding, reduced weight, and fatigue. In IBD, the immune system attacks the intestinal tract's inner wall, causing chronic inflammation and tissue damage. In particular, interlukin-6 and interlukin-17 act on immune cells, including T cells and macrophages, to amplify the immune responses so that tissue damage and morphological changes occur. Of note, excessive calorie intake and obesity also affect the immune system due to inflammation caused by lipotoxicity and changes in lipids supply. Similarly, individuals with IBD have alterations in liver function after sustained high-fat diet feeding. In addition, excess dietary fat intake, along with alterations in primary and secondary bile acids in the colon, can affect the onset and progression of IBD because inflammatory cytokines contribute to insulin resistance; the factors include the release of inflammatory cytokines, oxidative stress, and changes in intestinal microflora, which may also contribute to disease progression. However, interfering with de novo fatty acid synthase by deleting the enzyme acetyl-CoA-carboxylase 1 in intestinal epithelial cells (IEC) leads to the deficiency of epithelial crypt structures and tissue regeneration, which seems to be due to Lgr5+ intestinal stem cell function. Thus, conflicting reports exist regarding high-fat diet effects on IBD animal models. This review will focus on the pathological basis of the link between dietary lipids intake and IBD and will cover the currently available pharmacological approaches.

Stromal Cell Regulation of Intestinal Inflammatory Fibrosis

Intestinal inflammatory fibrosis is a severe consequence of inflammatory bowel diseases (IBDs). There is currently no cure for the treatment of intestinal fibrosis in IBD. Although inflammation is necessary for triggering fibrosis, the anti-inflammatory agents used to treat IBD are ineffective in preventing the progression of intestinal fibrosis and stricture formation once initiated, suggesting that inflammatory signals are not the sole drivers of fibrosis progression once it is established. Among multiple mechanisms involved in the initiation and progression of intestinal fibrosis in IBD, stromal cells play critical roles in mediating the process. In this review, we summarize recent progress on how stromal cells regulate intestinal fibrosis in IBD and how they are regulated by focusing on immune regulation and gut microbiota. We also outline the challenges moving forward in the field.

Multistate Model of the Natural History of Inflammatory Pancreatic Diseases: A Nationwide Population-based Cohort Study

BACKGROUND & AIMS

Understanding the nature of inflammatory pancreatic diseases is essential for planning health care system requirements and interventions. The aim of this study was to quantify the trajectories of inflammatory pancreatic diseases and their association with pancreatic cancer in a population-based setting.

METHODS

National health registries were used to identify all Danish residents (18 years or older) in the period from 2000 through 2018 with incident cases of acute pancreatitis (AP), recurrent acute pancreatitis (RAP), chronic pancreatitis (CP), and pancreatic cancer. We used a multistate model to examine transitions from a healthy state to intermediate states of acute pancreatic inflammation (AP and RAP) to chronic states (CP and pancreatic cancer) and, ultimately, death. Results were reported as transition incidence rates per 1000 person-years with 95% CIs.

RESULTS

There were 4,663,864 individuals included (mean age, 46 years; 51% were women). During a mean follow-up of 16.8 years, 31,396 individuals were diagnosed with incident AP, 5546 with RAP, 8898 with CP, and 18,182 with pancreatic cancer. The cumulative incidence of pancreatitis (acute and chronic) during the study period was 0.80% (95% CI, 0.79%-0.80%). The transition incidence rates to CP were 12.1 (95% CI, 8.1-18.1) from AP, 46.8 (95% CI, 31.6-69.3) from RAP, and 0.07 (95% CI, 0.04-0.13) from a healthy state. Similar patterns were observed for transitions to pancreatic cancer. Most patients diagnosed with CP (64.2%) and pancreatic cancer (96.4%) transitioned directly from a healthy state. Among patients with pancreatitis, 41.0% (95% CI, 40.5%-41.5%) died during follow-up.

CONCLUSIONS

The study findings revealed an increased risk of CP and pancreatic cancer in patients with a history of AP. However, most patients with CP and pancreatic cancer transitioned directly from a healthy state.

Prospective therapeutics for intestinal and hepatic fibrosis

Currently, there are no effective therapies for intestinal and hepatic fibrosis representing a considerable unmet need. Breakthroughs in pathogenesis have accelerated the development of anti-fibrotic therapeutics in recent years. Particularly, with the development of nanotechnology, the harsh environment of the gastrointestinal tract and inaccessible microenvironment of fibrotic lesions seem to be no longer considered a great barrier to the use of anti-fibrotic drugs. In this review, we comprehensively summarize recent preclinical and clinical studies on intestinal and hepatic fibrosis. It is found that the targets for preclinical studies on intestinal fibrosis is varied, which could be divided into molecular, cellular, and tissues level, although little clinical trials are ongoing. Liver fibrosis clinical trials have focused on improving metabolic disorders, preventing the activation and proliferation of hepatic stellate cells, promoting the degradation of collagen, and reducing inflammation and cell death. At the preclinical stage, the therapeutic strategies have focused on drug targets and delivery systems. At last, promising remedies to the current challenges are based on multi-modal synergistic and targeted delivery therapies through mesenchymal stem cells, nanotechnology, and gut-liver axis providing useful insights into anti-fibrotic strategies for clinical use.

Exploring Colitis through Dynamic T Cell Adoptive Transfer Models

Numerous animal models of colitis have provided important insights into the pathogenesis of inflammatory bowel disease (IBD), contributing to a better understanding of the underlying mechanisms for IBD. As aberrant CD4+ T cell responses play a critical role in the pathogenesis and development of IBD, T cell adoptive transfer models of colitis have become a valuable tool in investigating the immunopathogenesis of intestinal inflammation. While the adoptive transfer of CD4+ CD45RBhi T cells into immunedeficient recipient mice was the first discovered and is currently the most widely used model, several variations of the T cell transfer model have also been developed with distinct features. Here, we describe the history, principle, and characteristics of adoptive transfer colitis models and discuss their strengths, limitations, and applications.

Creating a Surgical Biobank: The Hershey Medical Center Experience

BACKGROUND

Tissue harvesting at the time of surgery offers surgeons and scientists a unique opportunity to discover and better understand disease pathophysiology. Tissue biobanking presents challenges in patient consents, specimen collection, preparation, and storage, but the potential for scientific discovery justifies the effort. Although the number of tissue biobanks is increasing worldwide, information regarding necessary infrastructure, process flow, and management of expected obstacles is lacking.

OBJECTIVE

To provide a framework and motivation for clinician scientists intending to start an intestinal tissue biobank under their direction.

DATA SOURCES

The Carlino Family Inflammatory Bowel and Colorectal Diseases Biobank is housed at the Milton S. Hershey Medical Center.

STUDY SELECTION

Review.

INTERVENTION

Implementation of a surgical tissue biobank at a large tertiary care institution.

MAIN OUTCOME MEASURES

Assess critical challenges and obstacles over the years as well as keys to the success of the program.

RESULTS

Over 2 decades, the institutional biobank grew from an IBD biobank to one which now incorporates thousands of surgical specimens representing numerous colorectal diseases. This was done through a process of refinement focusing on patient recruitment and an efficient consenting and specimen management process. The biobank's success is further insured by institutional, external, and philanthropic support; scientific collaborations; and sharing of biological specimens with other groups of dedicated researchers.

LIMITATIONS

This is a single-center experience in collecting surgically resected colorectal specimens.

CONCLUSIONS

Surgical specimen biobanks are essential in studying disease cause using genomics, transcriptomics, and proteomic technologies. Therefore, surgeons, clinicians, and scientists should build biobanks at their institutions to promote further scientific discovery and improve specimen diversity.

Immunometabolism changes in fibrosis: from mechanisms to therapeutic strategies

Immune cells are essential for initiating and developing the fibrotic process by releasing cytokines and growth factors that activate fibroblasts and promote extracellular matrix deposition. Immunometabolism describes how metabolic alterations affect the function of immune cells and how inflammation and immune responses regulate systemic metabolism. The disturbed immune cell function and their interactions with other cells in the tissue microenvironment lead to the origin and advancement of fibrosis. Understanding the dysregulated metabolic alterations and interactions between fibroblasts and the immune cells is critical for providing new therapeutic targets for fibrosis. This review provides an overview of recent advances in the pathophysiology of fibrosis from the immunometabolism aspect, highlighting the altered metabolic pathways in critical immune cell populations and the impact of inflammation on fibroblast metabolism during the development of fibrosis. We also discuss how this knowledge could be leveraged to develop novel therapeutic strategies for treating fibrotic diseases.

Targeting Th17 cells: a promising strategy to treat oral mucosal inflammatory diseases

With the improved quality of life, oral health is under increased pressure. Numerous common oral mucosal diseases, such as oral lichen planus(OLP) and gingivitis, are related to the destruction of the oral immune barrier. The cytokines secreted by T-helper 17 (Th17) cells are essential for maintaining oral immune homeostasis and play essential roles in immune surveillance. When antigens stimulate the epithelium, Th17 cells expand, differentiate, and generate inflammatory factors to recruit other lymphocytes, such as neutrophils, to clear the infection, which helps to maintain the integrity of the epithelial barrier. In contrast, excessive Th17/IL-17 axis reactions may cause autoimmune damage. Therefore, an in-depth understanding of the role of Th17 cells in oral mucosa may provide prospects for treating oral mucosal diseases. We reviewed the role of Th17 cells in various oral and skin mucosal systemic diseases with oral characteristics, and based on the findings of these reports, we emphasize that Th17 cellular response may be a critical factor in inflammatory diseases of the oral mucosa. In addition, we should pay attention to the role and relationship of "pathogenic Th17" and "non-pathogenic Th17" in oral mucosal diseases. We hope to provide a reference for Th17 cells as a potential therapeutic target for treating oral mucosal inflammatory disorders in the future.

Medicinal Plants, Phytochemicals and Regulation of the NLRP3 Inflammasome in Inflammatory Bowel Diseases: A Comprehensive Review

Ongoing research explores the underlying causes of ulcerative colitis and Crohn's disease. Many experts suggest that dysbiosis in the gut microbiota and genetic, immunological, and environmental factors play significant roles. The term "microbiota" pertains to the collective community of microorganisms, including bacteria, viruses, and fungi, that reside within the gastrointestinal tract, with a particular emphasis on the colon. When there is an imbalance or disruption in the composition of the gut microbiota, it is referred to as dysbiosis. Dysbiosis can trigger inflammation in the intestinal cells and disrupt the innate immune system, leading to oxidative stress, redox signaling, electrophilic stress, and inflammation. The Nod-like Receptor (NLR) Family Pyrin Domain Containing 3 (NLRP3) inflammasome, a key regulator found in immunological and epithelial cells, is crucial in inducing inflammatory diseases, promoting immune responses to the gut microbiota, and regulating the integrity of the intestinal epithelium. Its downstream effectors include caspase-1 and interleukin (IL)-1β. The present study investigated the therapeutic potential of 13 medicinal plants, such as Litsea cubeba, Artemisia anomala, Piper nigrum, Morus macroura, and Agrimonia pilosa, and 29 phytocompounds such as artemisitene, morroniside, protopine, ferulic acid, quercetin, picroside II, and hydroxytyrosol on in vitro and in vivo models of inflammatory bowel diseases (IBD), with a focus on their effects on the NLRP3 inflammasome. The observed effects of these treatments included reductions in IL-1β, tumor necrosis factor-alpha, IL-6, interferon-gamma, and caspase levels, and increased expression of antioxidant enzymes, IL-4, and IL-10, as well as regulation of gut microbiota. These effects could potentially provide substantial advantages in treating IBD with few or no adverse effects as caused by synthetic anti-inflammatory and immunomodulated drugs. However, additional research is necessary to validate these findings clinically and to develop effective treatments that can benefit individuals who suffer from these diseases.

Xue-jie-San prevents the early development of colitis-associated intestinal fibrosis by blocking Notch1 and FGL1 signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Xue-Jie-San (XJS), as a traditional Chinese herb prescription, has satisfactory effects on improving clinical symptoms and facilitating the healing of intestinal ulcers in patients with Crohn's disease (CD). This motivates the application of XJS on CD-associated complications.

AIM OF THE STUDY

Intestinal fibrosis is a debilitating complication of CD. Currently, there is no effective medication available for preventing or reversing CD-related intestinal fibrosis. This study aimed to assess the efficacy and underlying mechanisms of XJS in the treatment of colitis-associated intestinal fibrosis.

MATERIALS AND METHODS

A rat model of CD-related intestinal fibrosis was induced by 2,4,6-trinitrobenzene sulfonic acid administration and treated with XJS. The pathological changes of intestinal fibrosis were evaluated using Masson staining. Collagen deposition and epithelial-to-mesenchymal transition (EMT) were verified by immunohistochemical staining and western blot analysis. Endothelial-to-mesenchymal transition (EndoMT) was assessed with immunofluorescence and immunohistochemical staining as well as western blot analysis. Transmission electron microscopy was utilized to observe autophagosomes. The levels of autophagy-related proteins were detected via immunofluorescence staining and western blot. Finally, the mTOR/ULK1 signaling pathway regulated by Notch1 or FGL1 was analyzed by western blot.

RESULTS

The results found that XJS ameliorated intestinal fibrosis through reducing the deposition of collagens such as Collagen 1 and Collagen 3. XJS inhibited the EMT process by increasing E-cadherin levels and decreasing the expressions of N-cadherin, Vimentin and Snail, which played a crucial role in collagen secretion and intestinal fibrosis. In addition, XJS also repressed the EndoMT process as reflected by the upregulation of CD31 and VE-cadherin levels and the downregulation of FSP1 and α-SMA expressions. Autophagy was activated following XJS treatment via suppression of the mTOR/ULK1 signaling pathway. Furthermore, XJS acted as an inhibitor of Notch1 and FGL1 signals, both of which regulated the mTOR signaling.

CONCLUSIONS

Our findings validated that XJS prevented the early development of CD-related intestinal fibrosis by blocking the Notch1 and FGL1 signaling pathways to activate autophagy and thereby inhibit EMT and EndoMT.

Effect of the gut microbiota and their metabolites on postoperative intestinal motility and its underlying mechanisms

Gut microbiota is closely related to human health and disease because, together with their metabolites, gut microbiota maintain normal intestinal peristalsis. The use of antibiotics or opioid anesthetics, or both, during surgical procedures can lead to dysbiosis and affect intestinal motility; however, the underlying mechanisms are not fully known. This review aims to discuss the effect of gut microbiota and their metabolites on postoperative intestinal motility, focusing on regulating the enteric nervous system, 5-hydroxytryptamine neurotransmitter, and aryl hydrocarbon receptor.

Fibro-Stenosing Crohn's Disease: What Is New and What Is Next?

Fibro-stenosing Crohn's disease (CD) is a common disease presentation that leads to impaired quality of life and often requires endoscopic treatments or surgery. From a pathobiology perspective, the conventional view that intestinal fibro-stenosis is an irreversible condition has been disproved. Currently, there are no existing imaging techniques that can accurately quantify the amount of fibrosis within a stricture, and managing patients is challenging, requiring a multidisciplinary team. Novel therapies targeting different molecular components of the fibrotic pathways are increasing regarding other diseases outside the gut. However, a large gap between clinical need and the lack of anti-fibrotic agents in CD remains. This paper reviews the current state of pathobiology behind fibro-stenosing CD, provides an updated diagnostic and therapeutic approach, and finally, focuses on clinical trial endpoints and possible targets of anti-fibrotic therapies.

Biometabolites of Citrus unshiu Peel Enhance Intestinal Permeability and Alter Gut Commensal Bacteria

Flavanones in Citrus unshiu peel (CUP) have been used as therapeutic agents to reduce intestinal inflammation; however, the anti-inflammatory effects of their biometabolites remain ambiguous. Here, we identified aglycone-type flavanones, such as hesperetin and naringenin, which were more abundant in the bioconversion of the CUP than in the ethanol extracts of the CUP. We found that the bioconversion of the CUP induced the canonical nuclear factor-κB pathway via degradation of IκB in Caco-2 cells. To check the immune suppressive capacity of the aglycones of the CUP in vivo, we orally administered the bioconversion of the CUP (500 mg/kg) to mice for two weeks prior to the 3% dextran sulfate sodium treatment. The CUP-pretreated group showed improved body weight loss, colon length shortage, and intestinal inflammation than the control mice. We also found a significant decrease in the population of lamina propria Th17 cells in the CUP-pretreated group following dextran sodium sulfate (DSS) treatment and an increase in mRNA levels of occludin in CUP-treated Caco-2 cells. Pyrosequencing analysis revealed a decreased abundance of Alistipes putredinis and an increased abundance of Muribaculum intestinale in the feces of the CUP-pretreated mice compared to those of the control mice. Overall, these findings suggest that the pre-administration of CUP biometabolites may inhibit the development of murine colitis by modulating intestinal permeability and the gut microbiome.