Intraepithelial Mast Cells Research Articles

Mastocytosis and intraepithelial lymphocytosis in the ileum and colon characterize chronic Toxoplasma gondii infection in mice

Toxoplasma gondii is the causative agent of toxoplasmosis, a common zoonotic disease affecting vertebrates with high global incidence. For the parasite to disseminate throughout the body, it crosses the intestinal barrier, triggering inflammatory reactions. This study aimed to assess the tissue response in the ileum and colon of mice following chronic infection with T. gondii. Fourteen mice were divided into two groups: the infected group received 1000 T. gondii oocysts via gavage, and after 60 days, the mice were euthanized. The ileum and colon were collected and processed for histological analysis, inflammatory marker measurement and myenteric neuron analysis. Chronic infection resulted in a significant increase in intraepithelial lymphocytes and mast cells, as well as morphometric changes such as increased total intestinal wall thickness of the ileum, crypt depth, collagen fiber area, and a decrease in myeloperoxidase activity, without altering nitric oxide levels. While the number of myenteric neurons remained unchanged, there was an increase in vasoactive intestinal peptide expression. These results suggest persistence intestinal inflammatory stimuli in chronic T. gondii infection.

Differential changes in mast cells with food reintroduction in children with Eosinophilic Esophagitis.

Intraepithelial mast cells (MC) are increased in Eosinophilic Esophagitis (EoE) and reduced with elimination of dietary antigens. Single food reintroduction can identify triggers of eosinophilia however it remains unknown the extent to which specific foods trigger intraepithelial mastocytosis. We hypothesized that specific foods drive different degrees of MC inflammation. We previously reported a prospective pediatric EoE cohort treated with a 4-food elimination diet (4FED) with removal of soy, egg, wheat, milk. We retrieved unstained slides in which baseline, 4FED, and post-4FED diet reintroduction time points were available. Slides were stained with tryptase, and intraepithelial MCs were counted. Comparisons were made by stratifying patients by eosinophilia, basal cell hyperplasia (BCH), endoscopic abnormalities, and symptoms. Pearson correlation was assessed for MCs with eosinophilic, endoscopic and BCH severity, symptoms, and a novel mucosal activity score (MAS) combining endoscopic and histologic structural severity. Slides were available from 37 patients with at least 1 food reintroduced. MCs were significantly reduced with 4FED. Wheat led to increased intraepithelial MCs in the upper esophagus and with food-induced eosinophilia, while milk led to significantly increased MCs in the upper and lower esophagus and was significantly associated with patients with food-triggered eosinophilia, endoscopic abnormalities, BCH, and symptoms. MCs best correlated with the MAS during milk reintroduction. In children with EoE, MCs are reduced with 4FED. During milk reintroduction, significant increases in MCs were observed with all metrics of inflammation along with moderate correlation with structural mucosal activity that was not seen with other foods. This suggests milk exerts unique effects either directly or indirectly on MCs in the esophagus in EoE patients.

A new superhero, the intraepithelial mast cell, joins the “Guardians of the Gut”

A new superhero, the intraepithelial mast cell, joins the “Guardians of the Gut”

Intraepithelial mast cells drive gasdermin C-mediated type 2 immunity

A specialized population of mast cells residing within epithelial layers, currently known as intraepithelial mast cells (IEMCs), was originally observed over a century ago, yet their physiological functions have remained enigmatic. In this study, we unveil an unexpected and crucial role of IEMCs in driving gasdermin C-mediated type 2 immunity. During helminth infection, αEβ7 integrin-positive IEMCs engaged in extensive intercellular crosstalk with neighboring intestinal epithelial cells (IECs). Through the action of IEMC-derived proteases, gasdermin C proteins intrinsic to the epithelial cells underwent cleavage, leading to the release of a critical type 2 cytokine, interleukin-33 (IL-33). Notably, mast cell deficiency abolished the gasdermin C-mediated immune cascade initiated by epithelium. These findings shed light on the functions of IEMCs, uncover a previously unrecognized phase of type 2 immunity involving mast cell-epithelial cell crosstalk, and advance our understanding of the cellular mechanisms underlying gasdermin C activation.

High Intraepithelial Mast Cell Density in Warthin's Tumor.

Warthin's tumor, the second most frequent neoplasia of the parotid gland, is characterized by a proliferation of both epithelial and lymphoid components. In addition to epithelial and lymphoid cells, various other cell types are implicated to varying degrees in the immune response. Notably, mast cells have long been recognized as a consistent cell population within this tumor. Despite the historical acknowledgment of mast cell presence, their true distribution and significance within Warthin's tumor remain unclear. In this study, we aimed to elucidate the distribution and significance of mast cells in Warthin's tumor. Histochemical and immunohistochemical methods were employed for the evaluation of mast cells within tumor specimens. Our study revealed a notable concentration of mast cells in the epithelial component of Warthin's tumor. Microscopic examination showed predominant lymphoid and epithelial elements with occasional cystic formations. Immunohistochemical analysis identified mast cells in both components, emphasizing their role in the tumor microenvironment. Double immunostaining (mast cell tryptase and CD34) revealed no significant correlation between mast cells and blood vessels. Intraepithelial mast cells (IEMCs) had a significantly higher density in the epithelial component, suggesting a potential association with the tumor's benign nature. The relationship between IEMCs and epithelial cells, especially in the presence of cystic structures, offers valuable insights into the unique features of Warthin's tumor. Our study contributes to the understanding of mast cells in Warthin's tumor, highlighting a substantial concentration within the epithelial component. This knowledge may pave the way for further investigations into the roles of mast cells in the pathogenesis and treatment of Warthin's tumor.

Eosinophil-mast cell pattern of intraepithelial infiltration as a marker of severity in CRSwNP

Chronic rhinosinusitis with nasal polyps (CRSwNP) is defined as a Type 2 eosinophilic disease, while CRSsNP is considered a Type 1 neutrophilic disease. Since neutrophils are also activated in eosinophilic CRSwNP, the eosinophil–neutrophil dualism has been revaluated. Among the inflammatory cells infiltrating sinus-nasal tissues, the role of mast cells (MCs) is not already recognized, although Clinical-Cytological Grading, which defines the severity of CRSwNP, attributes to mixed eosinophil-MC forms of CRSwNP a greater risk of recurrence. We aimed to examine nasal polyps from both a cytological and histopathological point of view, to evaluate the presence and localization of MCs. Cytological and histological examination of 39 samples of nasal polyps were performed. Immunohistochemistry was used to evaluate the presence of Tryptase + CD117 + MCs, which were counted both in the epithelial layer and in the lamina propria. A statistically significant correlation was found between intraepithelial MCs and CRSwNP severity (p < 0.001) and between the total eosinophil count and the total mast cell count (p < 0.001). Cytological examination and immunohistochemistry were comparable in detecting the presence of intraepithelial MCs (p = 0.002). The histological cut-off of 6 intraepithelial MCs was identified to detect severe CRSwNP (p < 0.001). MCs have been shown to be located in the lamina propria of almost all eosinophilic nasal polyps without significantly affecting their severity. Intraepithelial MCs are associated with greater severity of CRSwNP. Histopathological criteria of the eosinophil-MC form of CRSwNP in addition to the eosinophilic one, should be defined to guarantee patients effective and tailored treatments.

Mast Cell Tryptase Promotes Airway Remodeling by Inducing Anti-Apoptotic and Cell Growth Properties in Human Alveolar and Bronchial Epithelial Cells

Bronchial and alveolar remodeling and impaired epithelial function are characteristics of chronic respiratory diseases. In these patients, an increased number of mast cells (MCs) positive for serine proteases, tryptase and chymase, infiltrate the epithelium and alveolar parenchyma. However, little is known regarding the implication of intraepithelial MCs on the local environment, such as epithelial cell function and properties. In this study, we investigated whether MC tryptase is involved in bronchial and alveolar remodeling and the mechanisms of regulation during inflammation. Using novel holographic live cell imaging, we found that MC tryptase enhanced human bronchial and alveolar epithelial cell growth and shortened the cell division intervals. The elevated cell growth induced by tryptase remained in a pro-inflammatory state. Tryptase also increased the expression of the anti-apoptotic protein BIRC3, as well as growth factor release in epithelial cells. Thus, our data imply that the intraepithelial and alveolar MC release of tryptase may play a critical role in disturbing bronchial epithelial and alveolar homeostasis by altering cell growth–death regulation.

Distribution of intraepithelial lymphocytes, mast cells, and goblet cells in the intestine of alpaca.

Intestinal diseases in ruminants are frequent and susceptible to invasion by exogenous substances, and the intestinal mucosal barrier is the first line of defence of the body's immune defence. At present, the study on the structure of intestinal mucosal immune barrier in alpaca is incomplete. Therefore, the alpaca intestines were studied to show the distribution characteristics of intestinal mucosal barrier structure and cells associated with immune system using histology, histochemistry, and immunohistochemistry. The results showed that the intestinal tract of alpaca was composed of mucosa, submucosa, muscularis, and serosa. Intraepithelial lymphocytes were distributed in mucosal epithelium and glands of the large intestine. Mast cells were distributed in each segment of the intestine, mainly in the intestinal lamina propria, intestinal glands, and duodenal glands around, as well as in the muscularis, and the particles of cytoplasm were obvious. Acidic goblet cells were mainly distributed in the ileal mucosal epithelium and ileal intestinal glands, while sialomucins were mainly expressed in the colon. The cells associated with the immune system in the intestinal mucosa of alpaca play an important role in protecting against foreign microbial invasion and infection, and this result provides a theoretical basis for revealing the occurrence of gastrointestinal diseases in alpaca.

Glutamate attenuates lipopolysaccharide induced intestinal barrier injury by regulating corticotropin-releasing factor pathway in weaned pigs.

ObjectiveThe purpose of this study was to evaluate the protection of glutamate (GLU) against the impairment in intestinal barrier function induced by lipopolysaccharide (LPS) stress in weaned pigs.MethodsTwenty-four weaned pigs were divided into four treatments containing: i) non-challenged control, ii) LPS-challenged control, iii) LPS+1.0% GLU, and iv) LPS+2.0% GLU. On day 28, pigs were treated with LPS or saline. Blood samples were collected at 0, 2, and 4 h post-injection. After blood samples collection at 4 h, all pigs were slaughtered, and spleen, mesenteric lymph nodes, liver and intestinal samples were obtained.ResultsDietary GLU supplementation inhibited the LPS-induced oxidative stress in pigs, as demonstrated by reduced malondialdehyde level and increased glutathione level in jejunum. Diets supplemented with GLU enhanced villus height, villus height/crypt depth and claudin-1 expression, attenuated intestinal histology and ultrastructure impairment induced by LPS. Moreover, GLU supplementation reversed intestinal intraepithelial lymphocyte number decrease and mast cell number increase induced by LPS stress. GLU reduced serum cortisol concentration at 4 h after LPS stress and downregulated the mRNA expression of intestinal corticotropin-releasing factor signal (corticotrophin-releasing factor [CRF], CRF receptor 1 [CRFR1], glucocorticoid receptor, tryptase, nerve growth factor, tyrosine kinase receptor A), and prevented mast cell activation. GLU upregulated the mRNA expression of intestinal transforming growth factor β.ConclusionThese findings indicate that GLU attenuates LPS-induced intestinal mucosal barrier injury, which is associated with modulating CRF signaling pathway.

TGFβ directs the phenotype and function of intraepithelial mast cells

Mast cells (MCs) are key effector cells that expand and participate in the pathophysiology of type 2 inflammatory disease, including asthma and chronic rhinosinusitis with nasal polyps (CRSwNP). MCs exhibit microenvironment-dependent protease phenotypes: in the airways and gut, sub-epithelial MCs co-express tryptase and chymase (MCTC), while those within epithelium mainly express tryptase alone (MCT). However, the signaling pathways driving these phenotypes are unclear. We previously identified a role for TGF-β signaling in directing murine MC intraepithelial airway phenotype and hypothesize that TGF-β plays a similar role for human MCs.

Location of eosinophils in the airway wall is critical for specific features of airway hyperresponsiveness and T2 inflammation in asthma.

Eosinophils are implicated as effector cells in asthma, but the functional implications of the precise location of eosinophils in the airway wall is poorly understood. We aimed to quantify eosinophils in the different compartments of the airway wall and associate these findings with clinical features of asthma and markers of airway inflammation. In this cross-sectional study, we utilised design-based stereology to accurately partition the numerical density of eosinophils in both the epithelial compartment and the subepithelial space (airway wall area below the basal lamina including the submucosa) in individuals with and without asthma and related these findings to airway hyperresponsiveness (AHR) and features of airway inflammation. Intraepithelial eosinophils were linked to the presence of asthma and endogenous AHR, the type that is most specific for asthma. In contrast, both intraepithelial and subepithelial eosinophils were associated with type 2 (T2) inflammation, with the strongest association between IL5 expression and intraepithelial eosinophils. Eosinophil infiltration of the airway wall was linked to a specific mast cell phenotype that has been described in asthma. We found that interleukin (IL)-33 and IL-5 additively increased cysteinyl leukotriene (CysLT) production by eosinophils and that the CysLT LTC4 along with IL-33 increased IL13 expression in mast cells and altered their protease profile. We conclude that intraepithelial eosinophils are associated with endogenous AHR and T2 inflammation and may interact with intraepithelial mast cells via CysLTs to regulate airway inflammation.

Carboxypeptidase inhibition by NvCI suppresses airway hyperreactivity in a mouse asthma model

Carboxypeptidase inhibition by NvCI suppresses airway hyperreactivity in a mouse asthma model

Mast cell tryptase enhances wound healing by promoting migration in human bronchial epithelial cells

ABSTRACT Epithelial damage and increase of intraepithelial mast cells (MC) are characteristics of asthma. The role of MC mediator tryptase and the protease-activated receptor-2 (PAR2) on epithelial wound healing is not fully investigated. Stimulation of bronchial epithelial cells (BECs) with tryptase promoted gap closure, migration and cellular speed compared to controls. Stimulated BECs had higher expression of migration marker CD151 compared to controls. Proliferation marker KI67 was upregulated in tryptase-stimulated BECs compared to controls. Treatment with PAR2 antagonist I-191 reduced gap closure, migration and cell speed compared to BECs stimulated with tryptase. We found that tryptase enhances epithelial wound healing by increased migration and proliferation, which is in part regulated via PAR2. Our data suggest that tryptase might be beneficial in tissue repair under baseline conditions. However, in a pathological context such as asthma with increased numbers of activated MCs, it might lead to epithelial remodeling and loss of function.

Exploring the origin and regulatory role of mast cells in asthma.

Mast cells have previously been thought to function solely as effector cells in asthma but more recent studies have indicated that mast cells may play a more central role in propagating and regulating lower airway inflammation in asthma. Initial studies have found increased numbers of mast cell progenitors (MCPs) in the peripheral blood of patients with asthma and these cells could contribute to the increased number of progenitors identified in the airways of patients with asthma. There are unique subpopulations of mast cells within the asthmatic airway, which are characterized by their physical location and distinguished by their expression profile of mast cell proteases. Intraepithelial mast cells are tightly associated with type-2 (T2) inflammation but additional studies have suggested a role for anti-mast cell therapies as a treatment for T2-low asthma. Mast cells have recently been shown to closely communicate with the airway epithelium and airway smooth muscle to regulate lower airway inflammation and airway hyperresponsiveness. Recent studies have better illuminated the central role of mast cells in regulating lower airway inflammation and airway hyperresponsiveness.

Mast Cell Activation in the Systemic Sclerosis Esophagus.

Previously, we discovered similar esophageal gene expression patterns in patients with systemic sclerosis (SSc) and eosinophilic esophagitis (EoE) where eosinophil/mast cell-targeted therapies are beneficial. Because SSc and EoE patients experience similar esophageal symptoms, we hypothesized that eosinophil/mast cell-directed therapy may potentially benefit SSc patients. Herein, we determine the association between esophageal mast cell quantities, gene expression and clinical parameters in order to identify SSc patients who may benefit from eosinophil/mast cell-directed therapy. Esophageal biopsies from SSc patients and healthy participants were stained for tryptase, a mast cell marker, and associations with relevant clinical parameters including 24h esophageal pH testing were assessed. Intra-epithelial mast cell density was quantified by semi-automated microscopy. Microarray data were utilized for functional and gene set enrichment analyses and to identify intrinsic subset (IS) assignment, an SSc molecular classification system that includes inflammatory, proliferative, limited and normal-like subsets. Esophageal biopsies from 40 SSc patients (39 receiving proton pump inhibition) and eleven healthy participants were studied. Mast cell numbers in both the upper esophagus (rs = 0.638, p = 0.004) and the entire (upper + lower) esophagus (rs = 0.562, p = 0.019) significantly correlated with acid exposure time percentage. The inflammatory, fibroproliferative, and normal-like ISs originally defined in skin biopsies were identified in esophageal biopsies. Although esophageal mast cell numbers in SSc patients and healthy participants were similar, gene expression for mast cell-related pathways showed significant upregulation in the inflammatory IS of SSc patients compared to patients classified as proliferative or normal-like. Esophageal mast cell numbers are heterogeneous in SSc patients and may correlate with acid exposure. Patients with inflammatory IS profiles in the esophagus demonstrate more tryptase staining. Mast cell targeted therapy may be a useful therapeutic approach in SSc patients belonging to the inflammatory IS, but additional studies are warranted.

Mast Cell Infiltration Is Associated With Persistent Symptoms and Endoscopic Abnormalities Despite Resolution of Eosinophilia in Pediatric Eosinophilic Esophagitis.

Mast cells (MCs) are increased in eosinophilic esophagitis (EoE). Endoscopic abnormalities, symptoms, and epithelial changes can persist after treatment despite a reduction of esophageal eosinophilia. It is unknown whether this could be due to persistent MC infiltration. We aimed to determine whether patients with histologically inactive (HI) EoE (defined as <15 eosinophils per high-powered field) with persistent symptoms, endoscopic, or epithelial abnormalities after treatment have increased MCs. Secondary analysis of prospective data from 93 children with EoE undergoing post-treatment endoscopy between 2011 and 2015. Thirty-five non-EoE controls were included. Immunohistochemistry for tryptase, an MC marker, was performed on mid and distal esophageal biopsies. Total and degranulated intraepithelial MCs per high-powered field (MC/hpf) were quantified. Symptoms and endoscopic findings were recorded at time of endoscopy. MC/hpf were compared between HI-EoE and control, and among HI-EoE based on endoscopic and histologic findings, and symptoms. Nine clinical remission (CR) patients were identified, with absence of endoscopic abnormalities and symptoms. MC/hpf were increased in HI-EoE compared with control (17 ± 11 vs 8 ± 6, P < 0.0). Patients with persistent endoscopic abnormalities had increased total (20 ± 12 vs 13 ± 10, P = 0.001) and degranulated (8 ± 6 vs 5 ± 4, P = 0.002) MC/hpf, with no difference in eosinophils. MC/hpf predicted furrowing (odds ratio = 1.06, P = 0.01) and rings (odds ratio = 1.05, P = 0.03) after controlling for treatment type, proton-pump inhibitor, eosinophils, and duration of therapy. Patients with persistent basal zone hyperplasia and dilated intercellular spaces had increased MC/hpf. Eosinophils were weakly correlated with MC/hpf in the mid (r = 0.30, P < 0.001) and distal (r = 0.29, P < 0.001) esophagus. Clinical remission patients had lower MC/hpf compared with patients with persistent symptoms and/or endoscopic abnormalities. MC density is increased in patients with endoscopic and epithelial abnormalities, as well as a few symptoms, despite resolution of esophageal eosinophilia after treatment. This association warrants further study to ascertain whether MCs play an eosinophil independent role in EoE.

Quantitation of Colonic Cells as Severity Markers in Patients with Irritable Bowel Syndrome

Background: Irritable bowel syndrome (IBS) is the most common gastrointestinal syndrome. Routine histopathology and immunohistochemistry (IHC) evaluations have shown an increase in the number of different inflammatory cells in the colon of IBS patients. In this study, we have compared the number of intraepithelial lymphocytes (IELs), eosinophils, mast cells and CD3+ T cells, in IBS patients and normal subjects. Materials and Methods: In 2016, seventy-nine patients with IBS and seventy-nine healthy subjects who underwent colonoscopy for other non-specific causes and with no pathologic findings, were enrolled in this cross-sectional study. Biopsy specimens obtained from the colon were stained, using IHC methods to determine the number of IELs, eosinophils, mast cells and CD3+ T cells. Quantitative and qualitative variables were compared between the two groups, using a Chi-square test and Student’s t-test. Results: Seventy-nine patients with IBS, 79.7% females with a mean age of 42.5±14.6 years, were recruited, as the case group, and seventy-nine individuals, 51.9% females with a mean age of 39.7±18.9 years, were enrolled as controls. The average number of IELs per high power fields (hpf) was found to be higher in the IBS group, and this difference was statistically significant (32.8±11.8 vs. 28.6±12.9; P=0.034). Also, the mean count/hpf of CD3+ T lymphocytes (23.1±7.9 vs. 20.2±8.1; P=0.024) and mast cells (7.6±3.1 vs. 6.6±3.0; P=0.041) were significantly higher in the IBS group, compared to the control group. The number of eosinophils was higher in the IBS group, but the differences were not statistically significant (P=0.066). Conclusion: According to the results, we suggest that analysis of immune cells and IELs in intestinal biopsies might be an appropriate method for diagnosis of IBS. [GMJ.2018;7:e1063]

Quantitation of Colonic Cells as Severity Markers in Patients with Irritable Bowel Syndrome

Background: Irritable bowel syndrome (IBS) is the most common gastrointestinal syndrome. Routine histopathology and immunohistochemistry (IHC) evaluations have shown an increase in the number of different inflammatory cells in the colon of IBS patients. In this study, we have compared the number of intraepithelial lymphocytes (IELs), eosinophils, mast cells and CD3+ T cells, in IBS patients and normal subjects. Materials and Methods: In 2016, seventy-nine patients with IBS and seventy-nine healthy subjects who underwent colonoscopy for other non-specific causes and with no pathologic findings, were enrolled in this cross-sectional study. Biopsy specimens obtained from the colon were stained, using IHC methods to determine the number of IELs, eosinophils, mast cells and CD3+ T cells. Quantitative and qualitative variables were compared between the two groups, using a Chi-square test and Student’s t-test. Results: Seventy-nine patients with IBS, 79.7% females with a mean age of 42.5±14.6 years, were recruited, as the case group, and seventy-nine individuals, 51.9% females with a mean age of 39.7±18.9 years, were enrolled as controls. The average number of IELs per high power fields (hpf) was found to be higher in the IBS group, and this difference was statistically significant (32.8±11.8 vs. 28.6±12.9; P=0.034). Also, the mean count/hpf of CD3+ T lymphocytes (23.1±7.9 vs. 20.2±8.1; P=0.024) and mast cells (7.6±3.1 vs. 6.6±3.0; P=0.041) were significantly higher in the IBS group, compared to the control group. The number of eosinophils was higher in the IBS group, but the differences were not statistically significant (P=0.066). Conclusion: According to the results, we suggest that analysis of immune cells and IELs in intestinal biopsies might be an appropriate method for diagnosis of IBS. [GMJ.2018;7:e1063]

Quantitation of Colonic Cells as Severity Markers in Patients with Irritable Bowel Syndrome.

Background: Irritable bowel syndrome (IBS) is the most common gastrointestinal syndrome. Routine histopathology and immunohistochemistry (IHC) evaluations have shown an increase in the number of different inflammatory cells in the colon of IBS patients. In this study, we have compared the number of intraepithelial lymphocytes (IELs), eosinophils, mast cells and CD3+ T cells, in IBS patients and normal subjects. Materials and Methods: In 2016, seventynine patients with IBS and seventy-nine healthy subjects who underwent colonoscopy for other non-specific causes and with no pathologic findings, were enrolled in this cross-sectional study. Biopsy specimens obtained from the colon were stained, using IHC methods to determine the number of IELs, eosinophils, mast cells and CD3+ T cells. Quantitative and qualitative variables were compared between the two groups, using a Chi-square test and Student’s t-test. Results: Seventy-nine patients with IBS, 79.7% females with a mean age of 42.5±14.6 years, were recruited, as the case group, and seventy-nine individuals, 51.9% females with a mean age of 39.7±18.9 years, were enrolled as controls. The average number of IELs per high power fields (hpf) was found to be higher in the IBS group, and this difference was statistically significant (32.8±11.8 vs. 28.6±12.9; P=0.034). Also, the mean count/hpf of CD3+ T lymphocytes (23.1±7.9 vs. 20.2±8.1; P=0.024) and mast cells (7.6±3.1 vs. 6.6±3.0; P=0.041) were significantly higher in the IBS group, compared to the control group. The number of eosinophils was higher in the IBS group, but the differences were not statistically significant (P=0.066). Conclusion: According to the results, we suggest that analysis of immune cells and IELs in intestinal biopsies might be an appropriate method for diagnosis of IBS.

Experimental asthma persists in IL-33 receptor knockout mice because of the emergence of thymic stromal lymphopoietin–driven IL-9+ and IL-13+ type 2 innate lymphoid cell subpopulations

IL-33 plays an important role in the development of experimental asthma. We sought to study the role of the IL-33 receptor suppressor of tumorigenicity 2 (ST2) in the persistence of asthma in a mouse model. We studied allergen-induced experimental asthma in ST2 knockout (KO) and wild-type control mice. We measured airway hyperresponsiveness by using flexiVent; inflammatory indices by using ELISA, histology, and real-time PCR; and type 2 innate lymphoid cells (ILC2s) in lung single-cell preparations by using flow cytometry. Airway hyperresponsiveness was increased in allergen-treated ST2 KO mice and comparable with that in allergen-treated wild-type control mice. Peribronchial and perivascular inflammation and mucus production were largely similar in both groups. Persistence of experimental asthma in ST2 KO mice was associated with an increase in levels of thymic stromal lymphopoietin (TSLP), IL-9, and IL-13, but not IL-5, in bronchoalveolar lavage fluid. Expectedly, ST2 deletion caused a reduction in IL-13+ CD4 T cells, forkhead box P3-positive regulatory T cells, and IL-5+ ILC2s. Unexpectedly, ST2 deletion led to an overall increase in innate lymphoid cells (CD45+lin-CD25+ cells) and IL-13+ ILC2s, emergence of a TSLP receptor-positive IL-9+ ILC2 population, and an increase in intraepithelial mast cell numbers in the lung. An anti-TSLP antibody abrogated airway hyperresponsiveness, inflammation, and mucus production in allergen-treated ST2 KO mice. It also caused a reduction in innate lymphoid cell, ILC2, and IL-9+ and IL-13+ ILC2 numbers in the lung. Genetic deletion of the IL-33 receptor paradoxically increases TSLP production, which stimulates the emergence of IL-9+ and IL-13+ ILC2s and mast cells and leads to development of chronic experimental asthma. An anti-TSLP antibody abrogates all pathologic features of asthma in this model.