Differentiation between ulcerative colitis and Crohn's disease by a quantitative immunohistochemical evaluation of T lymphocytes, neutrophils, histiocytes and mast cells

Decoding the mosaic of inflammatory bowel disease: Illuminating insights with single-cell RNA technology

Inflammatory bowel diseases (IBD), comprising ulcerative colitis (UC) and Crohn's disease (CD), are complex chronic inflammatory intestinal conditions with a multifaceted pathology, influenced by immune dysregulation and genetic susceptibility. The challenges in understanding IBD mechanisms and implementing precision medicine include deciphering the contributions of individual immune and non-immune cell populations, pinpointing specific dysregulated genes and pathways, developing predictive models for treatment response, and advancing molecular technologies. Single-cell RNA sequencing (scRNA-seq) has emerged as a powerful tool to address these challenges, offering comprehensive transcriptome profiles of various cell types at the individual cell level in IBD patients, overcoming limitations of bulk RNA sequencing. Additionally, single-cell proteomics analysis, T-cell receptor repertoire analysis, and epigenetic profiling provide a comprehensive view of IBD pathogenesis and personalized therapy. This review summarizes significant advancements in single-cell sequencing technologies for enhancing our understanding of IBD, covering pathogenesis, diagnosis, treatment, and prognosis. Furthermore, we discuss the challenges that persist in the context of IBD research, including the need for longitudinal studies, integration of multiple single-cell and spatial transcriptomics technologies, and the potential of microbial single-cell RNA-seq to shed light on the role of the gut microbiome in IBD.

Mast Cells as Important Regulators in Autoimmunity and Cancer Development

Mast cells are an essential part of the immune system and are best known as important modulators of allergic and anaphylactic immune responses. Upon activation, mast cells release a multitude of inflammatory mediators with various effector functions that can be both protective and damage-inducing. Mast cells can have an anti-inflammatory or pro-inflammatory immunological effect and play important roles in regulating autoimmune diseases including rheumatoid arthritis, type 1 diabetes, and multiple sclerosis. Importantly, chronic inflammation and autoimmunity are linked to the development of specific cancers including pancreatic cancer, prostate cancer, colorectal cancer, and gastric cancer. Inflammatory mediators released from activated mast cells regulate immune responses and promote vascular permeability and the recruitment of immune cells to the site of inflammation. Mast cells are present in increased numbers in tissues affected by autoimmune diseases as well as in tumor microenvironments where they co-localize with T regulatory cells and T effector cells. Mast cells can regulate immune responses by expressing immune checkpoint molecules on their surface, releasing anti-inflammatory cytokines, and promoting vascularization of solid tumor sites. As a result of these immune modulating activities, mast cells have disease-modifying roles in specific autoimmune diseases and cancers. Therefore, determining how to regulate the activities of mast cells in different inflammatory and tumor microenvironments may be critical to discovering potential therapeutic targets to treat autoimmune diseases and cancer.

Phytic acid modulates the morphology, immunological response of cytokines and β-defensins in porcine intestine exposed to deoxynivalenol and fumonisin B1

Occurrence of mycotoxins in agricultural products represents a risk for human and animal health. Therefore, there is a requirement of strategies to mitigate their harmful impacts. This study investigated the effects of phytic acid (IP6) on the immunological response of pro-(interleukin (IL)-1β, IL-6, IL-8, IL-10, interferon (IFN)-γ, tumour necrosis factor (TNF)-α) and anti-inflammatory (IL-10) cytokines and β-defensins 1 (pBD-1) and 2 (pBD-2) in porcine jejunal explants exposed to deoxynivalenol (DON) and fumonisin B1 (FB1). The explants were exposed to the following treatments: control, DON (10 μM), DON plus IP6 2.5 mM or 5 mM, FB1 (70 μM), FB1 IP6 plus 2.5 or 5 mM. The expression levels of the cytokines were measured by RT-qPCR. The exposure to FB1 and DON induced intestinal lesions. The presence of 2.5 and 5 mM IP6 inhibited the morphological changes induced by the mycotoxins. The explants exposed to DON showed an increase in the expression of IL-1β and IL-8 and a decrease in the levels of IL-6, IFN-γ, IL-10 and pBD-2. IP6 (5 mM) decreased the expression of IL-8 and increased the expression in pBD-1 and 2 compared to DON alone. FB1 induced a significant decrease in the levels of most of the pro-inflammatory cytokines, IL-10 and pBD-1, and an increase in IL-1β expression. The addition of IP6 5 mM induced significant increase in TNF-α expression compared to FB1. Taken together, the results suggest IP6 modulates immunological changes induced by DON and FB1 on intestinal mucosa resulting in beneficial effects that contribute to intestinal homeostasis and health.

Causative role of mast cell and mast cell-regulatory function of disialyllacto-N-tetraose in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) remains a fatal gastrointestinal disorder in neonates. Disialyllacto-N-tetraose (DSLNT), a function-unclear human milk-derived hexasaccharide, shows anti-NEC potential in previous animal studies. This study is aimed to explore the role of mast cell (MC), a fundamental cell type of mucosal immune system and protective DSLNT in regulating pathological process of NEC. For this purpose, infantile intestinal-tissues were collected from NEC neonates for examination of MCs and its proteases-positive cells. MC accumulation and MC-specific proteases (chymase, tryptase and dipeptidyl peptidase I) were firstly found in lesioned area of NEC infants in-vivo. Subsequent in-situ experiments on neonatal ileum segments showed that purified MC-chymase induced a destructive epithelial layer shedding from basement and microvascular endothelium damage in infantile intestinal segments. Human foreskin MC-activation model was established and DSLNT were applied; MC products (histamine and MC-proteases) were used as MC activation/degranulation indicators. In this in-vitro model, DSLNT pretreatment suppressed release of histamine, chymase and tryptase by MC to the tissue supernatants during lipopolysaccharide or complement C5a stimulation. Newborn rats were formula-hand-fed with or without DSLNT supplement and exposed to hypoxia/cold-stress to induce experimental-NEC-model. In NEC rats, DSLNT supplementation reduced the incidence and pathological scores of NEC, inhibited local accumulation of MC and reduced cytokines (IL-1β, IL-6 and TNF-α) levels in the ileum of rats. In conclusion, MC was causally implicated in epithelium barrier failure in pathogenesis of NEC. DSLNT favorably modulated MC homeostasis by regulating MC degranulation/accumulation, contributing to attenuated NEC. This indicated novel pathomechanisms and potential targets of NEC.

Inflamed Ulcerative Colitis Regions Associated With MRGPRX2-Mediated Mast Cell Degranulation and Cell Activation Modules, Defining a New Therapeutic Target

BACKGROUND & AIMS

Recent literature has implicated a key role for mast cells in murine models of colonic inflammation, but their role in human ulcerative colitis (UC) is not well established. A major advance has been the identification of mrgprb2 (human orthologue, MRGPX2) as mediating IgE-independent mast cell activation. We sought to define mechanisms of mast cell activation and MRGPRX2 in human UC.

METHODS

Colon tissues were collected from patients with UC for bulk RNA sequencing and lamina propria cells were isolated for MRGPRX2 activation studies and single-cell RNA sequencing. Genetic association of all protein-altering G-protein coupled receptor single-nucleotide polymorphism was performed in an Ashkenazi Jewish UC case-control cohort. Variants of MRGPRX2 were transfected into Chinese hamster ovary (CHO) and human mast cell (HMC) 1.1 cells to detect genotype-dependent effects on β-arrestin recruitment, IP-1 accumulation, and phosphorylated extracellular signal-regulated kinase.

RESULTS

Mast cell-specific mediators and adrenomedullin (proteolytic precursor of PAMP-12, an MRGPRX2 agonist) are up-regulated in inflamed compared to uninflamed UC. MRGPRX2 stimulation induces carboxypeptidase secretion from inflamed UC. Of all protein-altering GPCR alleles, a unique variant of MRGPRX2, Asn62Ser, was most associated with and was bioinformatically predicted to alter arrestin recruitment. We validated that the UC protective serine allele enhances β-arrestin recruitment, decreases IP-1, and increases phosphorylated extracellular signal-regulated kinase with MRGPRX2 agonists. Single-cell RNA sequencing defines that adrenomedullin is expressed by activated fibroblasts and epithelial cells and that interferon gamma is a key upstream regulator of mast cell gene expression.

CONCLUSION

Inflamed UC regions are distinguished by MRGPRX2-mediated activation of mast cells, with decreased activation observed with a UC-protective genetic variant. These results define cell modules of UC activation and a new therapeutic target.

Mast Cell Mediated Regulation of Small Intestinal Chloride Malabsorption in SAMP1/YitFc Mouse Model of Spontaneous Chronic Ileitis

In Inflammatory Bowel Disease (IBD), malabsorption of electrolytes (NaCl) results in diarrhea. Inhibition of coupled NaCl absorption, mediated by the dual operation of Na:H and Cl:HCO₃ exchangers on the brush border membrane (BBM) of the intestinal villus cells has been reported in IBD. In the SAMP1/YitFcs (SAMP1) mice model of spontaneous ileitis, representing Crohn’s disease, DRA (Downregulated in Adenoma) mediated Cl:HCO₃ exchange was shown to be inhibited secondary to diminished affinity of the exchanger for Cl. However, NHE3 mediated Na:H exchange remained unaffected. Mast cells and their secreted mediators are known to be increased in the IBD mucosa and can affect intestinal electrolyte absorption. However, how mast cell mediators may regulate Cl:HCO₃ exchange in SAMP1 mice is unknown. Therefore, the aim of this study was to determine the effect of mast cell mediators on the downregulation of DRA in SAMP1 mice. Mast cell numbers and their degranulation marker enzyme (β-hexosaminidase) levels were significantly increased in SAMP1 mice compared to control AKR mice. However, treatment of SAMP1 mice with a mast cell stabilizer, ketotifen, restored the β-hexosaminidase enzyme levels to normal in the intestine, demonstrating stabilization of mast cells by ketotifen. Moreover, downregulation of Cl:HCO₃ exchange activity was restored in ketotifen treated SAMP1 mice. Kinetic studies showed that ketotifen restored the altered affinity of Cl:HCO₃ exchange in SAMP1 mice villus cells thus reinstating its activity to normal. Further, RT-qPCR, Western blot and immunofluorescence studies showed that the expression levels of DRA mRNA and BBM protein, respectively remained unaltered in all experimental conditions, supporting the kinetic data. Thus, inhibition of Cl:HCO₃ exchange resulting in chloride malabsorption leading to diarrhea in IBD is likely mediated by mast cell mediators.

Increased Colonic Epithelial Permeability and Mucosal Eosinophilia in Ulcerative Colitis in Remission Compared With Irritable Bowel Syndrome and Health

BACKGROUND

Barrier dysfunction is recognized as a pathogenic factor in ulcerative colitis (UC) and irritable bowel syndrome (IBS), but it is unclear to what extent the factors related to barrier dysfunction are disease-specific. The aim of this study was to compare these aspects in UC patients in remission, IBS patients, and healthy controls (HCs).

METHODS

Colonic biopsies were collected from 13 patients with UC in remission, 15 patients with IBS-mixed, and 15 HCs. Ulcerative colitis patients had recently been treated for relapse, and biopsies were taken from earlier inflamed areas. Biopsies were mounted in Ussing chambers for measurements of intestinal paracellular permeability to 51chromium (Cr)-ethylenediaminetetraacetic acid (EDTA). In addition, biopsies were analyzed for mast cells and eosinophils by histological procedures, and plasma tumor necrosis factor (TNF)-α was assessed by ELISA.

RESULTS

Ussing chamber experiments revealed an increased 51Cr-EDTA permeability in UC and IBS (P < 0.05). The 51Cr-EDTA permeability was higher in UC compared with IBS (P < 0.005). There were increased numbers of mucosal mast cells and eosinophils in UC and IBS and more eosinophils in UC compared with IBS (P < 0.05). Also, increased extracellular granule content was found in UC compared with HCs (P < 0.05). The 51Cr-EDTA permeability correlated significantly with eosinophils in all groups. Plasma TNF-α concentration was higher in UC compared with IBS and HCs (P < 0.0005).

CONCLUSIONS

Results indicate a more permeable intestinal epithelium in inactive UC and IBS compared with HCs. Ulcerative colitis patients, even during remission, demonstrate a leakier barrier compared with IBS. Both eosinophil numbers and activation state might be involved in the increased barrier function seen in UC patients in remission.

Genetic Deficiency of the Histamine H4-Receptor Reduces Experimental Colorectal Carcinogenesis in Mice

Colorectal cancer (CRC), a severe complication of inflammatory bowel diseases, is a common type of cancer and accounts for high mortality. CRC can be modeled in mice by application of the tumor promoter, azoxymethane (AOM), in combination with dextran sodium sulfate (DSS), which are able to induce colitis-like manifestations. Active colitis correlates with high mucosal concentrations of histamine, which, together with the histamine receptor subtype 4 (H₄R), provide a pro-inflammatory function in a mouse colitis model. Here, we analyzed whether H₄R is involved in the pathogenesis of AOM/DSS-induced CRC in mice. As compared to wild type (WT) mice, AOM/DSS-treated mice lacking H₄R expression (TM) demonstrate ameliorated signs of CRC, i.e., significantly reduced loss of body weight, stiffer stool consistency, and less severe perianal bleeding. Importantly, numbers and diameters of tumors and the degree of colonic inflammation are dramatically reduced in TM mice as compared to WT mice. This is concomitant with a reduced colonic inflammatory response involving expression of cyclooxygenase 2 and the production of C-X-C motif chemokine ligand 1 (CXCL1) and CXCL2. We conclude that H₄R is involved in the tumorigenesis of chemically-induced CRC in mice via cyclooxygenase 2 expression and, probably, CXCL1 and CXCL2 as effector molecules.

Intestinal Mucosal Mast Cells: Key Modulators of Barrier Function and Homeostasis

The gastrointestinal tract harbours the largest population of mast cells in the body; this highly specialised leukocyte cell type is able to adapt its phenotype and function to the microenvironment in which it resides. Mast cells react to external and internal stimuli thanks to the variety of receptors they express, and carry out effector and regulatory tasks by means of the mediators of different natures they produce. Mast cells are fundamental elements of the intestinal barrier as they regulate epithelial function and integrity, modulate both innate and adaptive mucosal immunity, and maintain neuro-immune interactions, which are key to functioning of the gut. Disruption of the intestinal barrier is associated with increased passage of luminal antigens into the mucosa, which further facilitates mucosal mast cell activation, inflammatory responses, and altered mast cell⁻enteric nerve interaction. Despite intensive research showing gut dysfunction to be associated with increased intestinal permeability and mucosal mast cell activation, the specific mechanisms linking mast cell activity with altered intestinal barrier in human disease remain unclear. This review describes the role played by mast cells in control of the intestinal mucosal barrier and their contribution to digestive diseases.

Histamine drives severity of innate inflammation via histamine 4 receptor in murine experimental colitis

Ulcerative colitis (UC) patients exhibit elevated histamine, but how histamine exacerbates disease is unclear as targeting histamine 1 receptor (H1R) or H2R is clinically ineffective. We hypothesized that histamine functioned instead through the other colon-expressed histamine receptor, H4R. In humans, UC patient biopsies exhibited increased H4R RNA and protein expression over control tissue, and immunohistochemistry showed that H4R was in proximity to immunopathogenic myeloperoxidase-positive neutrophils. To characterize this association further, we employed both the oxazolone (Ox)- and dextran sulfate sodium (DSS)-induced experimental colitis mouse models and also found upregulated H4R expression. Mast cell (MC)-derived histamine and H4R drove experimental colitis, as H4R^-/- mice had lower symptom scores, neutrophil-recruitment mediators (colonic interleukin-6 (IL-6), CXCL1, CXCL2), and mucosal neutrophil infiltration than wild-type (WT) mice, as did MC-deficient Kit^W-sh/W-sh mice reconstituted with histidine decarboxylase-deficient (HDC^-/-) bone marrow-derived MCs compared with WT-reconstituted mice; adaptive responses remained intact. Furthermore, Rag2^-/- × H4R^-/- mice had reduced survival, exacerbated colitis, and increased bacterial translocation than Rag2^-/- mice, revealing an innate protective antibacterial role for H4R. Taken together, colonic MC-derived histamine initiates granulocyte infiltration into the colonic mucosa through H4R, suggesting alternative therapeutic targets beyond adaptive immunity for UC.

Mast Cells Exert Anti-Inflammatory Effects in an IL10-/- Model of Spontaneous Colitis

Mast cells are well established as divergent modulators of inflammation and immunosuppression, but their role in inflammatory bowel disease (IBD) remains to be fully defined. While previous studies have demonstrated a proinflammatory role for mast cells in acute models of chemical colitis, more recent investigations have shown that mast cell deficiency can exacerbate inflammation in spontaneous colitis models, thus suggesting a potential anti-inflammatory role of mast cells in IBD. Here, we tested the hypothesis that in chronic, spontaneous colitis, mast cells are protective. We compared colitis and intestinal barrier function in IL10^−/− mice to mast cell deficient/IL10^−/− (double knockout (DKO): Kit^Wsh/Wsh × IL10^−/−) mice. Compared with IL10^−/− mice, DKO mice exhibited more severe colitis as assessed by increased colitis scores, mucosal hypertrophy, intestinal permeability, and colonic cytokine production. PCR array analyses demonstrated enhanced expression of numerous cytokine and chemokine genes and downregulation of anti-inflammatory genes (e.g., Tgfb2, Bmp2, Bmp4, Bmp6, and Bmp7) in the colonic mucosa of DKO mice. Systemic reconstitution of DKO mice with bone marrow-derived mast cells resulted in significant amelioration of IL10^−/−-mediated colitis and intestinal barrier injury. Together, the results presented here demonstrate that mast cells exert anti-inflammatory properties in an established model of chronic, spontaneous IBD. Given the previously established proinflammatory role of mast cells in acute chemical colitis models, the present findings provide new insight into the divergent roles of mast cells in modulating inflammation during different stages of colitis. Further investigation of the mechanism of the anti-inflammatory role of the mast cells may elucidate novel therapies.

Neuroanatomy of lower gastrointestinal pain disorders

Chronic abdominal pain accompanying intestinal inflammation emerges from the hyperresponsiveness of neuronal, immune and endocrine signaling pathways within the intestines, the peripheral and the central nervous system. In this article we review how the sensory nerve information from the healthy and the hypersensitive bowel is encoded and conveyed to the brain. The gut milieu is continuously monitored by intrinsic enteric afferents, and an extrinsic nervous network comprising vagal, pelvic and splanchnic afferents. The extrinsic afferents convey gut stimuli to second order neurons within the superficial spinal cord layers. These neurons cross the white commissure and ascend in the anterolateral quadrant and in the ipsilateral dorsal column of the dorsal horn to higher brain centers, mostly subserving regulatory functions. Within the supraspinal regions and the brainstem, pathways descend to modulate the sensory input. Because of this multiple level control, only a small proportion of gut signals actually reaches the level of consciousness to induce sensation or pain. In inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) patients, however, long-term neuroplastic changes have occurred in the brain-gut axis which results in chronic abdominal pain. This sensitization may be driven on the one hand by peripheral mechanisms within the intestinal wall which encompasses an interplay between immunocytes, enterochromaffin cells, resident macrophages, neurons and smooth muscles. On the other hand, neuronal synaptic changes along with increased neurotransmitter release in the spinal cord and brain leads to a state of central wind-up. Also life factors such as but not limited to inflammation and stress contribute to hypersensitivity. All together, the degree to which each of these mechanisms contribute to hypersensitivity in IBD and IBS might be disease- and even patient-dependent. Mapping of sensitization throughout animal and human studies may significantly improve our understanding of sensitization in IBD and IBS. On the long run, this knowledge can be put forward in potential therapeutic targets for abdominal pain in these conditions.

Accumulation of Mast Cells in the Lesions and Effects of Antiallergic Drugs on the Patients with Inflammatory Bowel Disease

The pathomechanism of inflammatory bowel disease (IBD) has not yet been fully demonstrated. However, it is well known that mast cells are present in the gastrointestinal tract, suggesting that mast cells may take part in it. So, we investigated the number of mast cells in IBD, such as ulcerative colitis (UC) and eosinophilic colitis, and showed that the number of mast cells was increased in the inflammatory lesions. We also presented a case of UC which was treated successfully with an antiallergic drug, tranilast. Furthermore, possible new approaches to treating the disease with immunomodulators including suplatast are introduced. However, our investigations were performed with a limited number of patients with IBD, and additional further studies are required to confirm the findings.

Intestinal mast cells in gut inflammation and motility disturbances

Mast cells may be regarded as prototypes of innate immune cells that can be controlled by neuronal mediators. Their activation has been implicated in many types of neuro-inflammatory responses, and related disturbances of gut motility, via direct or indirect mechanisms that involve several mechanisms relevant to disease pathogenesis such as changes in epithelial barrier function or activation of adaptive or innate immune responses. Here we review the evidence for the involvement of mast cells in the inflammation of the bowel wall caused by bowel manipulation that leads to motility disturbances such as postoperative gastroparesis and ileus. Also in IBD there is substantial evidence for the involvement of mast cells and a mast cell-mediated neuroimmune interaction showing an increased number and an increased degranulation of mast cells. We discuss the potential of mast cell inhibition as a bona fide drug target to relief postoperative ileus. Further research on mast cell-related therapy either by stabilizing the mast cells or by blocking specific mast cell mediators as adjunctive therapy in IBD is encouraged, bearing in mind that several drugs currently used in the treatment of IBD possess properties affecting mast cell activities. This article is part of a Special Issue entitled: Mast cells in inflammation.

Induction and cellular expression of tartrate resistant acid phosphatase during dextran sodium sulphate induced colitis in rats

The aim of this study was to investigate the cellular and molecular expression of tartrate resistant acid phosphatase (TRAP) as a marker of activated macrophages in macrophage dependent dextran sulphate sodium (DSS)-induced colitis in rats. In normal colon, TRAP+/CX(3)CR(1)+ macrophages were located in the upper part of the lamina propria. In the early stage (day 1-3) of acute colitis prior to histopathological changes, induction of the cytokines TNFalpha, IL-12 and IFN gamma occurred concomitant with increased mRNA and enzyme activity of TRAP along with a slight increase of TRAP immunolabelling in macrophages of the upper lamina propria, suggesting induction of TRAP in resident macrophages. Among these cytokines, TNFalpha up-regulated TRAP expression in the RAW 264.7 monocyte/macrophage cell line. In a later phase (day 7) with fulminant colitis, a massive infiltration of macrophages including recruited TRAP+/CCR2+ cells was observed also in the lower part of the lamina propria as well as in the submuscular layer. Additionally, differentiated cellular expression of pro- and mature TRAP also suggest that mucosal macrophages in the lower part of lamina propria bordering the sub-mucosa provide a source of replenishment of macrophages situated in the upper lamina propria. In conclusion, induction of TRAP provides an early sign of macrophage responsiveness in DSS induced colitis.

Quantitative analysis of mast cells in benign and malignant colonic lesions: immunohistochemical study on formalin-fixed, paraffin-embedded tissues

BACKGROUND

Comparison of the number of mast cells in the active stage and that in remission in the same patients with ulcerative colitis with immunohistochemical staining remains to be elucidated, and analysis of the number of mast cells in benign and malignant colonic lesions is insufficient.

METHODS

Using immunohistochemical methods, morphological examinations of mast cells were undertaken in colonic tissues from 8 patients with ulcerative colitis and 10 patients with colonic primary cancer, which were formalin-fixed and paraffin-embedded. Changes in the number of mast cells in the active stage and in remission in the same patients with ulcerative colitis were investigated. Then, the number of mast cells in malignant tissues and adjacent healthy tissues obtained from the same patients with colonic primary cancer were compared, and finally the number of mast cells was compared among the samples from benign and malignant colonic lesions.

RESULTS

Accumulation of mast cells was found to be significant in the active stage of ulcerative colitis compared with remission in the same patients. The number of mast cells in colonic primary cancer was significantly increased compared with that in adjacent healthy tissues. The number of mast cells in ulcerative colitis was significantly greater than that in adjacent healthy tissues from patients with colonic primary cancer, irrespective of the stages of ulcerative colitis.

CONCLUSIONS

We were the first to analyse mast cells in the active stage and in remission in the same patients with ulcerative colitis using immunohisto-chemical methods, and compared the number of mast cells between benign and malignant colonic lesions.

Increased expression of long pentraxin PTX3 in inflammatory bowel diseases

The aims of this study were to investigate the expression of pentraxin-3 in inflamed gastrointestinal tissue in patients with inflammatory bowel diseases and to elucidate the usefulness of plasma pentraxin-3 level as an inflammation marker in patients with inflammatory bowel diseases. Pentraxin-3 immunoreactivity was found in infiltrating neutrophils and vessels in the inflamed gut. Plasma pentraxin-3 concentration in patients with active inflammatory bowel diseases was significantly higher than that of normal subjects and patients with inactive inflammatory bowel diseases. Significant positive correlations of clinical disease activity with plasma pentraxin-3 concentration and serum CRP concentration were found in patients with inflammatory bowel diseases. Pentraxin-3 is directly produced from the inflamed gut in inflammatory bowel diseases. In conclusion, plasma pentraxin-3 concentration is a useful marker for understanding the disease activity in patients with inflammatory bowel diseases.

Review article: gastrointestinal sensory and motor disturbances in inflammatory bowel disease - clinical relevance and pathophysiological mechanisms

BACKGROUND

It is well known that inflammation has a profound impact on the neuromuscular apparatus of the gastrointestinal tract during the inflammatory insult and in periods of remission, at the site of inflammation and at distance from this site. The importance of this interaction is illustrated by the higher prevalence of functional gut disorders in patients with inflammatory bowel disease.

AIMS

To document the epidemiological and clinical significance of functional alterations of gut motility and sensitivity in patients with inflammatory bowel disease and to formulate potential pathophysiological mechanisms.

RESULTS AND CONCLUSIONS

Functional gut disorders occur frequently in patients with inflammatory bowel disease, both during inflammatory episodes and in periods of remission, and have a major impact on their quality of life. The clinical manifestations of these motility and sensitivity disorders vary and are often difficult to treat, mainly because therapeutic guidelines and specific diagnostic tests to distinguish inflammatory bowel disease from functional gut disorders are lacking. Chronic bowel inflammation results in a complicated interaction between neuroendocrine serotonin-predominant cells of the mucosa, inflammatory cells (particularly mast cells) in the submucosa, the intrinsic and extrinsic innervation and the muscular apparatus including the interstitial cells of Cajal. The outcome of this interaction is a perturbation of gastrointestinal motor function, both locally and at distance from the site of inflammation and during both acute inflammation and remission.

Effect of oral lactulose on clinical and immunohistochemical parameters in patients with inflammatory bowel disease: a pilot study

Background

The prebiotic potential of lactulose is well established and preclinical studies demonstrated a protective effect of lactulose in murine models of colitis. The aim of the present study was to investigate the clinical and histological efficacy of lactulose in patients with inflammatory bowel disease (IBD), for which probiotic therapy yielded promising results.

Methods

Patients were treated with standard medication alone or combined with 10 g lactulose daily as adjuvant therapy for 4 months. Clinical efficacy of treatment was assessed using clinical activity indices, a quality of life index (IBDQ), endoscopic scores, defecation frequency and monitoring corticosteroid medication. Orsomucoid, alpha1-antitrypsin and other laboratory parameters were determined. In addition, in some participants colonic biopsies were analyzed with haematoxylin-eosin staining or with antibodies against HLA-DR, CD68, IgA and CD3, and evaluated systematically. All measurements were performed both at enrolment and at the end of the trial.

Results

14 patients presenting ulcerative colitis (UC) and 17 patients presenting Crohn's disease (CD), most of them in a clinically active state, were enrolled in this pilot study. After 4 month no significant improvement of clinical activity index, endoscopic score or immunohistochemical parameters was observed in CD or UC patients receiving lactulose in comparison to the control group. However, significant improvement of quality of life was observed in UC patients receiving lactulose compared to the control group (p = 0.04).

Conclusion

The findings of the present pilot study indicate that oral lactulose has no beneficial effects in IBD patients in particular with regard to clinical activity, endoscopic score or immunohistochemical parameters. The importance of the beneficial effect of lactulose in UC patients regarding the quality of life needs further evaluation in larger controlled clinical trials.

Trial registration

Current Controlled Trials ISRCTN92101486

Increase of mast cells may be associated with infiltration of eosinophils and proliferation of microvessels in gastric eosinophilic granuloma

BACKGROUND

Gastric eosinophilic granuloma (GEG) is a rare disease. Recently this disease has begun to increase in China. In the present study, the function and the role of mast cells (MC) in the pathogenesis of GEG were investigated.

METHODS

Paraffin-embedded tissue sections from 23 GEG patients and 15 gastric ulcer (GU) patients, were stained with antihuman mast cell tryptase for counting the MC and degranulated MC. Antihuman CD34 antibody was used for detecting the microvessel density (MVD) with immunohistochemical technique. Mast cell degranulation was also studied using electron microscopy.

RESULTS

The quantity of both MC and degranulated MC were higher in both GEG and GU than in normal gastric mucosa. The proportion of degranulated MC was higher in the GEG but in GU it was similar to normal mucosa. The MVD was higher in both GU and GEG than that in the normal gastric mucosa and it was higher in the high-MC group than in the low-MC group in GEG. The positive correlation between eosinophil and MC was present only in GEG, not in GU.

CONCLUSIONS

The infiltration of eosinophils and MVD may be associated with the increase of MC in GEG. This suggests that in addition to eosinophils, MC might be the important cells in the pathogenesis of GEG.

Accumulation of mast cells in the interstitium of eosinophilic colitis

INTRODUCTION

The mechanism of eosinophilic colitis remains unclear, and no case has been reported in which the number of mast cells was examined.

CASE REPORT

A 35-year-old man presented to our hospital with chief complaints of chills and consistent watery diarrhea after eating raw fresh-water fish. In blood examination, peripheral blood eosinophilia was found. Histological examination from biopsy specimens of both the ascending colon and rectum showed a prominent eosinophilic infiltration in the intestinal mucosa. Although a provocation test could not be performed due to lack of informed consent, a diagnosis of eosinophilic colitis was made on the basis of other findings. Immunohistochemical staining for human mast cell tryptase using monoclonal antibody against human mast cell tryptase showed an accumulation of mast cells in the colonic interstitium.

CONCLUSIONS

We report a case of eosinophilic colitis in which an accumulation of mast cells in the colonic interstitium was demonstrated.

Key role of mast cells and their major secretory products in inflammatory bowel disease

Historically, mast cells were known as a key cell type involved in type I hypersensitivity. Until last two decades, this cell type was recognized to be widely involved in a number of non-allergic diseases including inflammatory bowel disease (IBD). Markedly increased numbers of mast cells were observed in the mucosa of the ileum and colon of patients with IBD, which was accompanied by great changes of the content in mast cells such as dramatically increased expression of TNF-α, IL-16 and substance P. The evidence of mast cell degranulation was found in the wall of intestine from patients with IBD with immunohistochemistry technique. The highly elevated histamine and tryptase levels were detected in mucosa of patients with IBD, strongly suggesting that mast cell degranulation is involved in the pathogenesis of IBD. However, little is known of the actions of histamine, tryptase, chymase and carboxypeptidase in IBD. Over the last decade, heparin has been used to treat IBD in clinical practice. The low molecular weight heparin (LMWH) was effective as adjuvant therapy, and the patients showed good clinical and laboratory response with no serious adverse effects. The roles of PGD2, LTC4, PAF and mast cell cytokines in IBD were also discussed. Recently, a series of experiments with dispersed colon mast cells suggested there should be at least two pathways in man for mast cells to amplify their own activation-degranulation signals in an autocrine or paracrine manner. The hypothesis is that mast cell secretogogues induce mast cell degranulation, release histamine, then stimulate the adjacent mast cells or positively feedback to further stimulate its host mast cells through H₁ receptor. Whereas released tryptase acts similarly to histamine, but activates mast cells through its receptor PAR-2. The connections between current anti-IBD therapies or potential therapies for IBD with mast cells were discussed, implicating further that mast cell is a key cell type that is involved in the pathogenesis of IBD. In conclusion, while pathogenesis of IBD remains unclear, the key role of mast cells in this group of diseases demonstrated in the current review implicates strongly that IBD is a mast cell associated disease. Therefore, close attentions should be paid to the role of mast cells in IBD.

Cloning and expression of human colon mast cell carboxypeptidase

AIM: To clone and express the human colon mast cell carboxypeptidase (MC-CP) gene.

METHODS: Total RNA was extracted from colon tissue, and the cDNA encoding human colon mast cell carboxypeptidase was amplified by reverse-transcription PCR (RT-PCR). The product cDNA was subcloned into the prokaryotic expression vector pMAL-c2x and eukaryotic expression vector pPIC9K to construct prokaryotic expression vector pMAL/human MC-CP (hMC-CP) and eukaryotic pPIC9K/hMC-CP. The recombinant fusion protein expressed in E.coli was induced with IPTG and purified by amylose affinity chromatography. After digestion with factor Xa, recombinant hMC-CP was purified by heparin agarose chromatography. The recombinant hMC-CP expressed in Pichia pastoris (P.pastoris) was induced with methanol and analyzed by SDS-PAGE, Western blot, N-terminal amino acid sequencing and enzyme assay.

RESULTS: The cDNA encoding the human colon mast cell carboxypeptidase was cloned, which had five nucleotide variations compared with skin MC-CP cDNA. The recombinant hMC-CP protein expressed in E.coli was purified with amylose affinity chromatography and heparin agarose chromatography. SDS-PAGE and Western blot analysis showed that the recombinant protein expressed by E. coli had a molecular weight of 36 kDa and reacted to the anti-native hMC-CP monoclonal antibody (CA5). The N-terminal amino acid sequence confirmed further the product was hMC-CP. E. coli generated hMC-CP showed a very low level of enzymatic activity, but P. pastoris produced hMC-CP had a relatively high enzymatic activity towards a synthetic substrate hippuryl-L-phenylalanine.

CONCLUSION: The cDNA encoding human colon mast cell carboxypeptidase can be successfully cloned and expressed in E.coli and P. pastoris, which will contribute greatly to the functional study on hMC-CP.

Induction of tryptase and histamine release from human colon mast cells by IgE dependent or independent mechanisms

AIM: To investigate the tryptase and histamine release ability of human colon mast cells upon IgE dependent or independent activation and the potential mechanisms.

METHODS: Enzymatically dispersed cells from human colons were challenged with anti-IgE or calcium ionophore A23187, and the cell supernatants after challenge were collected. Both concentration dependent and time course studies with anti-IgE or calcium ionophore A23187 were performed. Tryptase release was determined with a sandwich ELISA procedure and histamine release was measured using a glass fibre-based fluorometric assay.

RESULTS: Both anti-IgE and calcium ionophore were able to induce dose dependent release of histamine from colon mast cells with up to approximately 60% and 25% net histamine release being achieved with 1 μg/mL calcium ionophore and 10 μg/mL anti-IgE, respectively. Dose dependent release of tryptase was also observed with up to approximately 19 ng/mL and 21 ng/mL release of tryptase being achieved with 10 μg/mL anti-IgE and 1 μg/ mL calcium ionophore, respectively. Time course study revealed that both tryptase and histamine release from colon mast cells stimulated by anti-IgE initiated within 10 sec and reached their maximum release at 6 min following challenge. Pretreatment of cells with metabolic inhibitors abolished the actions of anti-IgE as well as calcium ionophore. Tryptase and histamine release, particularly that induced by calcium ionophore was inhibited by pretreatment of cells with pertussis toxin.

CONCLUSION: Both anti-IgE and calcium ionophore are able to induce significant release of tryptase and histamine from colon mast cells, indicating that this cell type is likely to contribute to the pathogenesis of colitis and other mast cell associated intestinal diseases.

A novel inflammation-related mouse colon carcinogenesis model induced by azoxymethane and dextran sodium sulfate

To develop an efficient animal model for colitis-related carcinogenesis, male Crj: CD-1 (ICR) mice were given a single intraperitoneal administration (10 mg/kg body weight) of a genotoxic colonic carcinogen, azoxymethane (AOM), and a 1-week oral exposure (2% in drinking water) to a non-genotoxic carcinogen, dextran sodium sulfate (DSS), under various protocols. At week 20, colonic neoplasms (adenocarcinomas, 100% incidence with 5.60 +/- 2.42 multiplicity; and adenomas, 38% incidence with 0.20 +/- 0.40 multiplicity) with dysplastic lesions developed in mice treated with AOM followed by DSS. Protocols in which AOM was given during or after DSS administration induced a few tubular adenomas or no tumors in the colon. Immunohistochemical investigation of such dysplasias and neoplasms revealed that all lesions were positive for beta-catenin, cyclooxygenase-2 and inducible nitric oxide synthase, but did not show p53 immunoreactivity. The results indicate that 1-week administration of 2% DSS after initiation with a low dose of AOM exerts a powerful tumor-promoting activity in colon carcinogenesis in male ICR mice, and may provide a novel mouse model for investigating colitis-related colon carcinogenesis and for identifying xenobiotics with modifying effects.