The role of eosinophils in inflammatory bowel disease

Immune dysregulation in the functional gastrointestinal disorders

Gastrointestinal conditions may be broadly classified into two: organic and functional disease, with functional disorders accounting for the majority of patients with chronic gastrointestinal symptoms. Functional gastrointestinal disorders (FGIDs) present with no obvious pathology or well-accepted biochemical mechanism and, as such, treatment strategies are limited and focus on symptoms rather than cure. Irritable bowel syndrome and functional dyspepsia are the most widely recognised FGIDs, and there is a growing body of evidence to suggest an underlying inflammatory phenotype in subsets with these conditions. Here, we discuss the current knowledge of immune involvement in FGIDs and the commonalities between the different manifestations of FGIDs and propose a new hypothesis, potentially defining an underlying immunopathological basis of these conditions.

Natural killer cells limit cardiac inflammation and fibrosis by halting eosinophil infiltration

Myocarditis is a leading cause of sudden cardiac failure in young adults. Natural killer (NK) cells, a subset of the innate lymphoid cell compartment, are protective in viral myocarditis. Herein, we demonstrated that these protective qualities extend to suppressing autoimmune inflammation. Experimental autoimmune myocarditis (EAM) was initiated in BALB/c mice by immunization with myocarditogenic peptide. During EAM, activated cardiac NK cells secreted interferon γ, perforin, and granzyme B, and expressed CD69, tumor necrosis factor-related apoptosis-inducing ligand treatment, and CD27 on their cell surfaces. The depletion of NK cells during EAM with anti-asialo GM1 antibody significantly increased myocarditis severity, and was accompanied by elevated fibrosis and a 10-fold increase in the percentage of cardiac-infiltrating eosinophils. The resultant influx of eosinophils to the heart was directly responsible for the increased disease severity in the absence of NK cells, because treatment with polyclonal antibody asialogangloside GM-1 did not augment myocarditis severity in eosinophil-deficient ΔdoubleGATA1 mice. We demonstrate that NK cells limit eosinophilic infiltration both indirectly, through altering eosinophil-related chemokine production by cardiac fibroblasts, and directly, by inducing eosinophil apoptosis in vitro. Altogether, we define a new pathway of eosinophilic regulation through interactions with NK cells.

Stability of 3-bromotyrosine in serum and serum 3-bromotyrosine concentrations in dogs with gastrointestinal diseases

Background

3-Bromotyrosine (3-BrY) is a stable product of eosinophil peroxidase and may serve as a marker of eosinophil activation. A gas chromatography/mass spectrometry method to measure 3-BrY concentrations in serum from dogs has recently been established and analytically validated. The aims of this study were to determine the stability of 3-BrY in serum, to determine the association between peripheral eosinophil counts and the presence of an eosinophilic infiltrate in the gastrointestinal tract, and to compare serum 3-BrY concentrations in healthy dogs (n = 52) and dogs with eosinophilic gastroenteritis (EGE; n = 27), lymphocytic-plasmacytic enteritis (LPE; n = 25), exocrine pancreatic insufficiency (EPI; n = 26), or pancreatitis (n = 27).

Results

Serum 3-BrY concentrations were stable for up to 8, 30, and 180 days at 4°C, −20°C, and −80°C, respectively. There was no significant association between peripheral eosinophil count and the presence of eosinophils in the GI tissues (P = 0.1733). Serum 3-BrY concentrations were significantly higher in dogs with EGE (median [range] = 5.04 [≤0.63-26.26] μmol/L), LPE (median [range] = 3.60 [≤0.63-15.67] μmol/L), and pancreatitis (median [range] = 1.49 [≤0.63-4.46] μmol/L) than in healthy control dogs (median [range] = ≤0.63 [≤0.63-1.79] μmol/L; P < 0.0001), whereas concentrations in dogs with EPI (median [range] = 0.73 [≤0.63-4.59] μmol/L) were not different compared to healthy control dogs.

Conclusions

The present study revealed that 3-BrY concentrations were stable in serum when refrigerated and frozen. No relationship between peripheral eosinophil count and the presence of eosinophils infiltration in the GI tissues was found in this study. In addition, serum 3-BrY concentrations were increased in dogs with EGE, but also in dogs with LPE and pancreatitis. Further studies are needed to determine whether measurement of 3-BrY concentrations in serum may be useful to assess patients with suspected or confirmed EGE or LPE.

Severe eosinophilic infiltration in colonic biopsies predicts patients with ulcerative colitis not responding to medical therapy

AIM

Eosinophils are potent proinflammatory cells that are involved in the pathogenesis of ulcerative colitis (UC). We evaluated the infiltration of eosinophils into the lamina propria in patients with active and inactive ulcerative colitis (UC) and investigated its clinical significance, among other variables, in predicting the outcome of medical treatment in active disease.

METHOD

We studied colorectal biopsy specimens from 18 UC patients with disease in long-standing remission, from 22 patients with active disease who responded to therapy (12 with complete response and 10 with partial response) and from 10 patients who were nonresponders. Demographic information was obtained at baseline, and clinical, endoscopic and laboratory data were obtained at baseline and 12 weeks post-treatment. We evaluated five histological features: mucosal ulceration; mucosal erosions; crypt abscesses; cryptitis; and eosinophilic infiltration of the lamina propria. The severity of these lesions was graded as: none or minimal; mild; moderate; or severe. Statistical analyses were performed between responders and nonresponders for differences in demographic, clinical, laboratory, endoscopic and histological parameters.

RESULTS

Laboratory, endoscopic and histological parameters were significantly improved after treatment only in the complete responders group. Analyses of baseline data revealed no significant differences in parameters between complete or partial responders and nonresponders, except for a less severe eosinophilic infiltration of lamina propria in complete responders (P < 0.05). Multiple logistic regression analysis showed that severe eosinophilic infiltration in colonic biopsies was the most significant predictor of poor response to medical therapy.

CONCLUSION

Assessing the severity of eosinophilic infiltration in the lamina propria of colonic biopsies in patients with ulcerative colitis could be a valuable predictive tool of response to medical therapy.

Endoscopic biopsy samples of naïve "colitides" patients: role of basal plasmacytosis

BACKGROUND

Although it is usually not difficult to diagnose inflammatory bowel disease (IBD) on surgical resection specimens, difficulties sometimes arise in differentiating these entities from other forms of colitis on endoscopic biopsy specimens. Basal plasmacytosis is considered as an early feature of IBD colitis, but it is rare in non-IBD colitides.

AIMS

We assessed the value of basal plasmacytosis as an individual variable in untreated patients with colitis.

PATIENTS AND METHODS

Archival slides of patients with untreated colitis (66 IBD and 49 non-IBD) and 20 controls with complete (from the terminal ileum to the rectum) endoscopic biopsy sampling were evaluated blindly for the presence of basal plasmacytosis and a possible association with the presence of eosinophils in the same anatomical location.

RESULTS

Overall, basal plasmacytosis was present in at least one anatomical segment in 58% of cases, and it was always present in patients with IBD, whereas it was sparsely found (9%) in patients with other colitides and in controls. Basal plasmacytosis in three or more segments had more than 80% probability for a patient to be classified as IBD, with the segmental distribution being different between ulcerative colitis and Crohn's disease. Additionally, basal plasmacytosis was always accompanied by eosinophils intermingled with plasma cells in the same anatomical position.

CONCLUSION

As an individual feature, basal plasmacytosis (accompanied by eosinophils) is a strong feature suggesting IBD, particularly when present in three or more colonic segments. This fact may be useful in the evaluation of endoscopic biopsies from patients with "colitis".

Carotenoids, inflammation, and oxidative stress--implications of cellular signaling pathways and relation to chronic disease prevention

Several epidemiologic studies have shown that diets rich in fruits and vegetables reduce the risk of developing several chronic diseases, such as type 2 diabetes, atherosclerosis, and cancer. These diseases are linked with systemic, low-grade chronic inflammation. Although controversy persists on the bioactive ingredients, several secondary plant metabolites have been associated with these beneficial health effects. Carotenoids represent the most abundant lipid-soluble phytochemicals, and in vitro and in vivo studies have suggested that they have antioxidant, antiapoptotic, and anti-inflammatory properties. Recently, many of these properties have been linked to the effect of carotenoids on intracellular signaling cascades, thereby influencing gene expression and protein translation. By blocking the translocation of nuclear factor κB to the nucleus, carotenoids are able to interact with the nuclear factor κB pathway and thus inhibit the downstream production of inflammatory cytokines, such as interleukin-8 or prostaglandin E2. Carotenoids can also block oxidative stress by interacting with the nuclear factor erythroid 2-related factor 2 pathway, enhancing its translocation into the nucleus, and activating phase II enzymes and antioxidants, such as glutathione-S-transferases. In this review, which is organized into in vitro, animal, and human investigations, we summarized current knowledge on carotenoids and metabolites with respect to their ability to modulate inflammatory and oxidative stress pathways and discuss potential dose-health relations. Although many pathways involved in the bioactivity of carotenoids have been revealed, future research should be directed toward dose-response relations of carotenoids, their metabolites, and their effect on transcription factors and metabolism.

Severe eosinophilia in children: a diagnostic dilemma

The differential diagnosis of hypereosinophilia includes both primary (clonal and idiopathic) and secondary medical conditions. Here we raise the awareness of physicians to the unusual causes of hypereosinophilic states and describe the molecular assays used in the diagnosis of hypereosinophilia. Two unusual cases of hypereosinophilia in children that were initially misdiagnosed are reported. T-cell receptor gene rearrangement, skewed X inactivation, fluorescence in situ hybridization analysis, and chromosomal karyotyping were used to reach the final correct diagnosis. Both patients displayed significant eosinophilia and were initially misdiagnosed as having parasitic infection. Nonspecific T-cell clonal expansion was diagnosed in 1 patient based on the clonality of the T-cell receptor variable γ-chain and the skewed chromosome inactivation. The second patient was diagnosed with B-lineage acute lymphoblastic leukemia with a translocation (5;14) (q13;q32) that is well known to be associated with hypereosinophilia. The level of awareness to clonal expansion of WBC subsets which can cause hypereosinophilia should be high when evaluating a patient with extreme eosinophilia. Advanced molecular assays to detect clonal expansion should be used to exclude aberrant clonal processes in such patients.

Recurrent blood eosinophilia in ulcerative colitis is associated with severe disease and primary sclerosing cholangitis

BACKGROUND AND AIMS

Eosinophils are implicated in the pathogenesis of inflammatory bowel disease (IBD). A subset of IBD patients develops blood eosinophilia, and the clinical profile of these patients is undefined. We sought to characterize IBD patients with and without eosinophilia.

METHODS

We studied a prospective registry of 1,176 IBD patients followed in a tertiary referral center. Patients who developed eosinophilia at any time were identified by electronic medical record query. We performed a chart review case-control study comparing patients with recurrent eosinophilia versus randomly selected disease-matched patients with no history of eosinophilia. Histological analysis was performed on selected cases and controls.

RESULTS

Eosinophilia at any time was more prevalent in ulcerative colitis (UC) patients than Crohn's disease patients (22.2 versus 12.7%), as was recurrent eosinophilia (3.4 versus 0.7%). UC patients with recurrent eosinophilia were predominantly male compared with the control UC population (81.3 versus 46.9%) and had higher rates of colectomy for either medically refractory disease or dysplasia/cancer than control UC patients (56.3 versus 15.6%). Primary sclerosing cholangitis (PSC) occurred in 37.5% of UC patients with recurrent eosinophilia compared with only 3.1% in the UC controls. Histological analysis of random diagnostic samples from UC patients with recurrent eosinophilia demonstrated a normal eosinophil pattern as seen in the control UC population.

CONCLUSIONS

Eosinophilia-associated UC is a subgroup of IBD associated with severe colitis and PSC. Further studies are warranted to characterize molecular mechanisms underlying eosinophilia-associated UC and to determine optimal approaches for therapy.

The ubiquitin ligase adaptor Ndfip1 regulates T cell-mediated gastrointestinal inflammation and inflammatory bowel disease susceptibility

Nedd4 family interacting protein 1 (Ndfip1) is an adaptor protein that regulates Itch, an E3 ubiquitin ligase that ubiquitylates JunB, thereby preventing interleukin (IL)-4 and IL-5 production. Mice lacking Ndfip1 or Itch develop T helper type 2 (T(H)2)-mediated inflammation in the skin and lungs and die prematurely. In this study we show that Ndfip1-/- mice also develop inflammation in the gastrointestinal tract. Inflammation is characterized by infiltration of eosinophils and T cells and is accompanied by a failure to gain weight. T cells are both necessary and sufficient for eosinophil recruitment and inflammation. This is because Ndfip1-/- T cells become activated and produce IL-5. Itch mutant mice develop much less severe gastrointestinal inflammation, suggesting that Ndfip1 regulation of Itch cannot entirely account for this phenotype and that Ndfip1 has both Itch-dependent and Itch-independent roles. Ndfip1 may also regulate human disease. We found single-nucleotide polymorphisms in the Ndfip1 locus that associate with inflammatory bowel disease. Taken together, our data support a role for Ndfip1 in gastrointestinal inflammation in both mice and humans.

Gastrointestinal eosinophils in health, disease and functional disorders

Eosinophils are potent innate immune cells that home to the gastrointestinal tract where they participate in host immunity to luminal pathogens, and help to maintain intestinal epithelial homeostasis. However, these cells are now recognized to have key functions in the pathogenesis of numerous other disorders of the gastrointestinal tract, including primary eosinophilic gastrointestinal disease, common functional conditions, such as dyspepsia, and also in gastrointestinal disorders in patients with allergic disease. We are just beginning to understand the potential pathological role of eosinophils in gastrointestinal disease, and it is increasingly likely that gastroenterologists and histopathologists will need to account for the presence of gastrointestinal eosinophils and relate their presence to gastrointestinal symptoms. This Review discusses the role of gastrointestinal eosinophils in health and disease, including their associations with functional and allergic disorders.

Clinicopathological significance of eosinophil granulocyte infiltration in the intestinal mucosa of patients with ulcerative colitis

AIM: To examine eosinophil granulocyte (EG) infiltration in the intestinal mucosa of patients with ulcerative colitis (UC) and analyze the correlation of EG infiltration with clinical activity index (CAI), endoscope activity index (EAI) and histopathological parameters of the disease.

METHODS: Forty-five UC patients treated at our hospital from November 2007 to December 2008 were divided into two groups according to disease activity: active group (n = 45) and remission group (n = 39, patients achieving complete and partial remission after treatment for 6 weeks or more during entire treatment course). CAI, EAI and histopathological parameters were used to evaluate disease activity. The number of EGs was counted.

RESULTS: The intestinal mucosa of UC patients was infiltrated mainly by neutrophils, lymphocytes, plasmatocytes and EGs. The inflammatory infiltration was more severe in the active group than in the remission group. Pathological changes in small vessels and glands in the lamina propria as well as crypt abscess were more severe in the active group than in the remission group, while mesenchymal change was more significant in the remission group than in the active group. A significant negative correlation was found between the number of EGs and neutrophils in remitted patients (r = 0.568, P = 0.001). In the active group, EG infiltration was positively correlated with lymphadenosis and formation of folliculi lymphaticus (r = 0.755 and 0.524, respectively; both P < 0.01), and negatively with focal hemorrhage (r = -0.385, P = 0.010). In the remission group, EG infiltration was positively correlated with goblet cell disappearance (r = 0.349, P = 0.046).

CONCLUSION: EG infiltration is a potential parameter for evaluating UC activity.

Faecal and serum levels of eosinophil cationic protein in a healthy paediatric population

BACKGROUND

Eosinophil cationic protein (ECP) has been regarded as an excellent marker of eosinophil activation in various diseases where eosinophil-mediated inflammation plays a role. Recently, it has been suggested as a faecal marker of intestinal inflammation in several immune-mediated diseases with gastrointestinal expression. Owing to the scarcity of information at paediatric age, the establishment of reference values is necessary before further clinical studies.

OBJECTIVE

To determine faecal and serum ECP levels in healthy children and their association with other biological parameters, thereby providing background additional validation data for this age group.

METHODS

Faecal and serum ECP levels were available from healthy Caucasian children recruited at a regular outpatient clinic. Exclusion criteria were: chronic illnesses, acute illness, mucosal bleeding and recent pharmacological medication. Faecal and serum ECP levels and faecal a1AT were determined by commercial radioimmunoassay and serum IgE by fluoroenzyme immunoassay Uni-CAP.

RESULTS

Mean and median faecal ECP levels were 1.93 microg/g and 1.20 microg/g, respectively (range 0.41-22.20),while the corresponding serum ECP levels were 13.50 microg/L and 9.54 microg/L, respectively (range 0.20-74.8). The cut-offs found were 2.80 microg/g and 16.89 microg/L for faecal and serum ECP, respectively. A significant (p=0.001) increase in serum, but not in faecal, ECP levels was found among patients with high peripheral eosinophil blood count. Neither faecal nor serum ECP levels were influenced by serum IgE levels.

CONCLUSIONS

Faecal and serum ECP levels, as determined in the present study, add background information concerning reference levels at paediatric age for further studies indifferent clinical settings.

Induced sputum eosinophilia in ulcerative colitis patients: the lung as a mirror image of intestine?

BACKGROUND

Ulcerative colitis (UC) is a systemic disease of unknown etiology with extra-intestinal manifestation. Induced sputum (IS) non-invasively assesses extrapulmonary involvement in Crohn's disease. We sought to determine whether there is a cellular marker of lung injury in UC patients detectable by IS.

METHODS

Nineteen UC patients (mean age 46.4+/-11.3 years, disease duration 8.6+/-7.5 years [range 1-25 years] 68.4% males) were studied, 6 with active disease and 13 in remission. Eleven received 5-ASA, 5 received steroids and/or azathioprine and 3 patients were untreated. UC patients were compared with 27 healthy non-smoker controls. IS was recovered after 20 min inhalation of 3% saline with an ultrasonic nebulizer by the selecting plugs method, and 300 cells were differentially cell counted in cytospin Giemsa-stained slides. CD4/CD8 subsets were identified by FACS. Pulmonary function tests were performed by the Jaeger Masterlab spirometer.

RESULTS

UC patients' IS contained higher %eosinophils than controls (p=0.05) and lower FEV(1)/FVC ratios (p=0.001). Steroid- and/or azathioprine-treated patients had significantly lower FEV(1)/FVC ratios than only 5-ASA-treated patients (p=0.019). Eosinophil infiltration in airways was high in 5-ASA-treated patients compared to those receiving steroids and/or azathioprine (p=0.046) and those with less extensive disease (p=0.05). Using a cutoff of 3% eosinophils, IS had a sensitivity of 67% and specificity of 73% to differentiate patients with a cutoff of 70 eosinophils/mm(2) in biopsy.

CONCLUSIONS

The percentage of sputum eosinophils is significantly different between UC patients with proctitis and pancolitis. These immune abnormalities may be a common pattern that is present throughout the mucosae.

Classification of eosinophilic gastrointestinal diseases

Diagnosis of eosinophilic gastrointestinal diseases is based on morphological evaluation with regard to localization and density of eosinophil infiltration of the mucosa and/or deeper parts of the oesophagus, stomach, and bowel in biopsy or resection specimens. As with eosinophils in any tissue, in the majority of diseases they are probably a sequel of acute inflammation and do not indicate any specific disease. Eosinophil morphology includes intact cells with bilobated nuclei and eosinophil granules in the cytoplasm and extracellular tissue following activation/degranulation. There is no fixed number of eosinophils that can be used as a cut-off criterion to define disease. Associated histopathological features observed in eosinophilic gastrointestinal disease depend on the site of manifestation and primary disease. Eosinophils are typically increased in allergy-associated colitis in adults and allergic proctocolitis in infants, eosinophilic gastroenteritis and eosinophilic oesophagitis. Their presence can also suggest a drug-induced eosinophilia or the presence of a parasitic infection. In general, eosinophils are increased in inflammatory bowel disease (IBD). They are seen in reflux oesophagitis, coeliac disease, and microscopic and infectious colitis. Eosinophils may be a feature of polyarteriitis nodosa and Churg-Strauss syndrome, and can accompany connective-tissue disease as well as malignant lymphomas and adenocarcinomas of gastrointestinal mucosa.