Intestinal Neutrophil Research Articles

Diabetic Hyperglycemia: A Facilitating Factor in Systemic Capillary Leak

Background. Diabetes is a known risk factor for increased morbidity and mortality following trauma and serious injuries. The current studies were designed to investigate the effects of diabetes on both local and systemic injury following mesenteric ischemia–reperfusion in rats.Materials and methods. Rats received streptozotocin (65 mg/kg ip) to induce diabetes or vehicle and were studied 8 weeks later. In another group of normal rats, hyperglycemia (blood sugar >200 mg/dl) was induced by intravenous infusion of a glucose solution. Rats were subjected to 10 or 30 min of superior mesenteric artery occlusion followed by 1 or 4 h of reperfusion or a sham operation. Intestinal mucosal injury, neutrophil infiltration, and changes in capillary leak were determined. Flow cytometry was used to assess neutrophil “priming state.”Results. Euglycemic and acutely hyperglycemic rats exhibited no mucosal injury after 10 min of ischemia, but did show significant damage after 30 min of ischemia followed by 1 h of reperfusion. Euglycemic rats had significant capillary leak following 30 min of ischemia and 4 h of reperfusion that was associated with an increase in the neutrophil priming state. In acute hyperglycemia, leak occurred after 30 min of ischemia and only 1 h of reperfusion. Diabetic rats exhibited significant mucosal injury after 10 min of ischemia and 1 h of reperfusion that was associated with significant capillary leak and increased neutrophil priming state.Conclusion. Altered neutrophil activity contributes to the increased susceptibility to local intestinal and systemic injury in diabetes.

Total parenteral nutrition supplementation with glutamine improves survival after gut ischemia/reperfusion.

Total parenteral nutrition (TPN) alters gut cytokines and mucosal immunity and increases intercellular adhesion molecule-1 (ICAM-1) expression, gut neutrophil levels, and mortality after gut ischemia. Supplementation of TPN with glutamine partially supports mucosal immunity by preserving respiratory and intestinal IgA levels, maintaining the proper IgA-stimulating cytokine milieu within the intestine, and reducing intestinal ICAM-1 expression and neutrophil accumulation. This work investigates whether glutamine supplementation of TPN affects mortality in mice after gut ischemic insult. Thirty-eight mice were randomized to receive chow, TPN, or 2% glutamine-supplemented TPN (GLN-TPN) for 5 days. After feeding their respective diets, gut ischemia/reperfusion (I/R) was induced with superior mesenteric artery occlusion for 30 minutes followed by resuscitation with 1 mL saline. Survival was recorded until 72 hours after reperfusion. Survival time was significantly reduced in the TPN-fed mice compared with both chow-fed and GLN-TPN-fed mice (p < .05). Survival at 72 hours after reperfusion was also significantly lower in the TPN-fed mice than in the chow-fed and GLN-TPN-fed mice (p < .05) Glutamine supplementation of TPN significantly improves survival after gut I/R, suggesting modulation of the inflammatory response or improved gut tolerance to low-flow states.

Human neutrophil lipocalin is a unique marker of neutrophil inflammation in ulcerative colitis and proctitis.

Accumulation and infiltration by neutrophil granulocytes is a prominent feature in the local inflammatory process in ulcerative colitis (UC). The present study was performed to evaluate human neutrophil lipocalin (HNL) as a specific neutrophil marker in the inflamed lesions of the colon and rectum in patients with colitis and proctitis. The activity of intestinal neutrophils with respect to release of granule proteins was studied in 18 patients with UC (10 with colitis and eight with isolated proctitis) and in 18 healthy controls using perfusion fluid and biopsies from the sigmoid colon and rectum. The released amounts of the neutrophil granule proteins HNL and myeloperoxidase (MPO) were determined by radioimmunoassays, and the location of HNL and MPO in biopsies from colonic mucosa was examined by immunohistochemistry. Mucosal release of HNL and MPO was increased 10-55-fold in patients with colitis and proctitis compared with controls. Their bowel biopsies demonstrated that only neutrophils were stained with anti-HNL. We also found correlations between HNL and levels of granulocyte/macrophage-colony stimulating factor (GM-CSF) and interleukin 8 (IL-8) in perfusion fluids from the sigmoidal segments of patients with proctitis, between HNL and GM-CSF in rectal segments in patients with proctitis, and in sigmoidal segments in patients with colitis. We conclude that the increased release of HNL and MPO in colorectal perfusion fluids indicates neutrophil involvement in the local inflammatory process, and suggest that HNL may serve as a specific marker of intestinal neutrophil activation in UC. GM-CSF, and to some extent IL-8, may play a role in neutrophil accumulation and priming in this disease.

Endothelial protective and antishock effects of a selective estrogen receptor modulator in rats.

This study investigated whether idoxifene, a selective estrogen receptor modulator (SERM), exerted protective effects against ischemia-reperfusion-induced shock. Ovariectomized rats were treated with vehicle, idoxifene, or 17beta-estradiol for 4 days. Rats were subjected to splanchnic artery occlusion (SAO) followed by reperfusion (SOA/R). In vehicle-treated rats, SAO/R resulted in hypotension, hemoconcentration, increased plasma tumor necrosis factor (TNF)-alpha levels, intestinal neutrophil accumulation, and endothelial dysfunction. 17beta-Estradiol treatment increased plasma estradiol concentration and reduced SAO/R-induced tissue injury. Idoxifene treatment had no effect on plasma estradiol concentration but reduced SAO/R-induced hemoconcentration (+8.8 +/- 1.3 vs. +14 +/- 1.3% in the vehicle group, P < 0.01), TNF-alpha production (98 +/- 3.2 vs. 214 +/- 13 pg/ml, P < 0.01), and neutrophil accumulation (0.025 +/- 0.005 vs. 0.047 +/- 0.005 U/g protein, P < 0.01). It also improved endothelial function, prolonged survival time (172 +/- 3.5 vs. 147 +/- 8 min, P < 0.01), and increased survival rate (69 vs. 23%, P < 0.01). Moreover, treatment with 17beta-estradiol or idoxifene in vivo reduced TNF-alpha-induced endothelial dysfunction in vitro. Taken together, these results demonstrated that idoxifene exerted estrogen-like, endothelial-protective, and antishock effects in ovariectomized rats, suggesting that SERMs have therapeutic potential in tissue injury resulting from ischemia-reperfusion.

Immunity in rats against Eimeria separata: oocyst excretion, effects on endogenous stages and local tissue response after primary and challenge infections.

The aim of the study was the characterization of the local immune response of Lewis rats to Eimeria separata, a caecum-dwelling coccidium. Rats infected twice at 10-day intervals with 5,000 oocysts developed a high degree of immunity to a heavy challenge with 100,000 oocysts, reducing the oocyst production by > 98% when compared with naive recipients. Histopathological investigations performed over a period of 0-72 h post-infection (pi) showed that 1st generation schizonts, developed within 24 h pi, represented the major target stages, although later stages were also affected. Preinfected animals showed significantly more lymphocytes in the caecum wall than naive animals. An increase in lymphocyte numbers after challenge observed in both groups was enhanced in challenged animals up to 36 h pi. The number of lamina propria lymphocytes predominantly was increased after primary infection whereas in repeatedly infected animals the increase also concerned intraepithelial lymphocytes. In addition, the numbers of plasma cells were enhanced in the caecum wall of immune animals. Macrophage infiltration in the caecum wall followed a similar time course in both groups up to 36 h pi. A subsequent further rise up to 48 h pi was enhanced in naive rats. Tissue infiltrations with eosinophils and mast cells were observed predominantly in the repeatedly infected rats. No obvious changes occurred with intestinal neutrophils and goblet cells. In conclusion, caecum tissue alterations suggest an early local immune response, which is related to development and maturation of the parasite.

Bombesin improves burn-induced intestinal injury in the rat

This study was designed to determine the effect of exogenous bombesin (10 μg/kg/day, subcutaneously, three times a day) on intestinal hypomotility and neutrophil infiltration in the early and late phases of burn injury (partial-thickness, second-degree burn of the skin). In acute (2 h after burn injury) or chronic (3 days after) burn groups, intestinal transit was delayed, which was reversed by bombesin treatment. In the acute burn group, but not in the chronic group, increased MPO activity was also reduced by bombesin treatment. The results demonstrate that bombesin ameliorates the intestinal inflammation due to burn injury, involving a neutrophil-dependent mechanism.

Luminal neutrophil migration in ileoanal pouches studied by whole gut lavage

White cell scintigraphy has shown that neutrophils migrate into the gut wall and lumen in ileoanal pouches. We aimed to establish whether whole gut lavage fluid can be used to investigate intestinal neutrophil migration in ileoanal pouches. A prospective single centre study recruiting consecutive patients. Whole gut lavage with polyethylene glycol electrolyte solution was performed in 56 (32 men, 24 women) ileoanal pouch patients who had undergone colectomy for ulcerative colitis; the first clear effluent was collected, processed and stored at -70 degrees C. The fluid was assayed for neutrophil granulocyte elastase using a specific colorimetric assay, IgG, albumin, alpha1-antitrypsin, haemoglobin and cytokines IL-1beta and IL-8 using previously described techniques. Patients' disease activity was characterized following pouchoscopy and biopsy. Patients with pouchitis had significantly higher levels of granulocyte elastase in whole gut lavage fluid compared with those without pouchitis. Patients with detectable granulocyte elastase had higher pouchoscopy score, more severe mucosal neutrophil infiltration and protein loss and bleeding. These patients had significantly higher levels of cytokines IL-1beta and IL-8 in the whole gut lavage fluid, compared with patients with undetectable granulocyte elastase. Whole gut lavage fluid samples may provide a useful investigative tool to study mucosal inflammation and luminal neutrophil migration in ileoanal pouches.

The delays in intestinal motility and neutrophil infiltration following burn injury in rats involve endogenous endothelins

This study was carried out to investigate the role of endogenous endothelins in intestinal motility following bum injury by using a nonselective endothelin-1 (ET-1) antagonist and to evaluate the ET-1-mediated reactive oxygen metabolite formation and neutrophil infiltration following burn injury. In 2 h and 3 day postburn groups, transit indices were significantly decreased as compared to corresponding sham groups. Transit index was not significantly changed by PD156252 pretreatment in the 2 h postburn group, whereas the delay in transit was abolished in the ET-antagonist treated 3 day postbum group. In the 2 h postburn group, tissue-associated myeloperoxidase (MPO) activity value was found to be increased compared to corresponding sham group, while PD156252 pretreatment partially reversed this effect. Although MPO activity levels were not significantly different between 3 day postburn and corresponding sham groups, MPO levels showed a significant increase in ET antagonist-treated group as compared to the corresponding burn group. In the early phase of the burn, there was no significant difference in protein oxidation levels among the groups. In the 3 day postburn group, protein oxidation levels in ET-antagonist-treated group showed an increase compared to its corresponding burn group. In conclusion, the results demonstrate that endogenous endothelins have an important role in the systemic response to burn injury, as observed by a delay in intestinal motility and an infiltration of neutrophils. Although the results of the animal studies are not readily applicable to burned patients, the present study may suggest that the burned patient's condition should be carefully evaluated to secure a proper and early enteral feeding.

Complement activation mediates intestinal injury after resuscitation from hemorrhagic shock.

Endothelial cell injury after hemorrhage and resuscitation (HEM/RES) might contribute to intestinal hypoperfusion and mucosal ischemia. Our recent work suggests that the injury might be the result of complement activation. We hypothesized that HEM/RES causes complement-mediated endothelial cell dysfunction in the small intestine. Male Sprague-Dawley rats (195-230 g) were anesthetized and HEM to 50% of baseline mean arterial pressure for 60 minutes. Just before RES, animals received either soluble complement receptor-1 (sCR1, 15 mg/kg) to inhibit complement activation or saline vehicle. Resuscitation was with shed blood and an equal volume of saline. Two hours after RES, the small bowel was harvested to evaluate intestinal nitric oxide synthase activity (NOS), neutrophil influx, histology, and oxidant injury. HEM/RES induced tissue injury, increased neutrophil influx, and reduced NOS activity by 50% (vs. SHAM), all of which were completely prevented by sCR1 administration. There were no observed differences in oxidant injury between the groups. Histologic tissue injury, increased neutrophil influx, and impaired NOS activity after HEM/RES were all prevented by complement inhibition. Direct oxidant injury did not seem to be a major contributor to these alterations. Complement inhibition after HEM might ameliorate reperfusion injury in the small intestine by protecting the endothelial cell, reducing neutrophil influx and preserving NOS function.

The role of xanthine oxidase in platelet activating factor induced intestinal injury in the rat

BackgroundXanthine oxidase (XO) is an important source of reactive oxygen species in the small intestine.AimsTo examine the interaction of platelet activating factor (PAF), XO, and neutrophils in mediating intestinal injury...

Direct evidence of mast cell involvement in Clostridium difficile toxin a—induced enteritis in mice

Background & Aims: The pathogenesis of Clostridium difficile toxin A–induced intestinal inflammation is not completely understood. The aim of this study was to define the contribution of mast cells to the fluid secretion and neutrophil infiltration associated with toxin A–induced enteritis. Methods: Fluid secretion and neutrophil infiltration in toxin A– or buffer–challenged ileal loops were assessed in normal, mast cell–deficient, and mast cell–deficient Kit W/Kit W-v mice that had undergone selective repair of their mast cell deficiency. The effect of a specific substance P–receptor antagonist was also studied. Results: Intestinal fluid secretion and neutrophil recruitment were significantly diminished in mast cell–deficient Kit W/Kit W-v and mast cell–deficient Mgf Sl/Mgf Sl-d mice compared with the respective normal mice. Mast cell–reconstituted Kit W/Kit W-v mice showed responses similar to the normal congenic mice. Administration of a specific substance P–receptor antagonist (CP-96,345) reduced toxin A–induced intestinal fluid secretion and inhibited neutrophil infiltration in normal, mast cell–deficient Kit W/Kit W-v , and mast cell–reconstituted Kit W/Kit W-v mice. Conclusions: C. difficile toxin A elicits intestinal fluid secretion and neutrophil infiltration by both mast cell–dependent and –independent pathways, and substance P participates in both pathways. GASTROENTEROLOGY 1998;114:956-964

Nitric oxide attenuates and xanthine oxidase exaggerates lung damage-induced gut injury.

Aspirated gastric contents can evoke multiorgan failure. We hypothesized that secondary intestinal epithelial dysfunction after lung damage would be mediated by xanthine oxidase (XO) and antagonized by endogenous gut nitric oxide (NO). Isosmotic saline or HCl solutions were instilled intratracheally in anesthetized rats, and intestinal injury was assessed 190 min later by measuring the blood-to-lumen clearance of 51Cr-labeled EDTA (51Cr-EDTA clearance) and gut wall neutrophil population density. Intratracheal HCl increased 51Cr-EDTA clearance, and this transepithelial leak was attenuated by either systemic L-arginine or intraluminal NO and by chronic dietary pretreatment with allopurinol or sodium tungstate. Conversely, lung damage-induced gut leak was exaggerated by NO synthase inhibition or intravenous XO administration. Intratracheal HCl also increased intestinal wall neutrophil density and myeloperoxide activity. We conclude that two enzymatic systems involved in remote gut barrier dysfunction after endobronchial acidification are XO as mediator and NO synthase as antagonist.

Nitric oxide inhibits rat intestinal secretion by Clostridium difficile toxin A but not Vibrio cholerae enterotoxin

BACKGROUND & AIMS: Intestinal inflammation is associated with increased synthesis of nitric oxide, whereas inhibition of NO synthase (NOS) reduces experimental chronic intestinal inflammation. The aim of this study was to test the effects of NO blockers and donors on acute intestinal inflammation induced by Clostridium difficile toxin A in rat ileum. METHODS: Rats received NOS inhibitors or NO donors before measurement of toxin-mediated ileal secretion and permeability changes. Mucosal mast cell and neutrophil activity were measured by release of rat mast cell protease II and myeloperoxidase activity, respectively. RESULTS: NOS inhibitors augmented but an NO donor inhibited toxin A- mediated ileal secretion and permeability when given before but not after toxin administration. Neither an NOS inhibitor nor an NO donor had any effect on cholera toxin-mediated secretion. Mast cell degranulation and neutrophil infiltration occurred after injection of toxin A or an NOS inhibitor, whereas the NO donor blocked both toxin A effects. CONCLUSIONS: NOS inhibitors augmented and an NO donor blocked the intestinal effects of toxin A but not of cholera toxin. NO protects against toxin A by inhibition of intestinal mast cells and neutrophils, which are activated by toxin A, but not by cholera toxin. (Gastroenterology 1996 Aug;111(2):409-18)

P-selectin mediates intestinal ischemic injury by enhancing complement deposition

Ischemia and reperfusion injury of rodent intestine is complement mediated. P-selectin antagonism reduces local injury, yet neutrophil depletion does not. This study tests the thesis that the protective mechanism of P-selectin antagonists involves complement inhibition. We subjected rats (n = 86) to 50 minutes of complete mesenteric ischemia and 4 hours of reperfusion. Treatment with a monoclonal antibody (PB1.3) against P-selectin reduced intestinal injury as judged by 125I-albumin permeability index (7.33 +/- 0.40) compared with saline solution treatment (11.4 +/- 0.49) (p < 0.05). However, intestinal neutrophil sequestration assessed by myeloperoxidase assay was unchanged. Immunohistochemistry revealed that mucosal C5b-9 was deposited in animals treated with saline solution and was absent in the sham group. PB1.3 treatment reduced C5b-9 deposition in the intestinal mucosa compared with that in animals treated with saline solution (p < 0.05). Neutrophil-dependent remote lung injury assessed by 125I-albumin permeability and pulmonary myeloperoxidase assay were not significantly reduced by PB1.3. Treatment with a soluble form of P-selectin ligand, sialyl Lewisx (sLex), reduced intestinal myeloperoxidase (0.065 +/- 0.006) compared with saline solution treatment (0.136 +/- 0.02) (p < 0.05), but it did not reduce permeability. Remote lung permeability was reduced (4.52 +/- 0.65 x 10(-3)) by sLex compared with saline solution treatment (6.11 +/- 0.41 x 10(-3)) (p < 0.05). Antagonizing the lectin domain of P-selectin and thereby neutrophil adhesion was without local benefit in this model. In contrast, PB1.3 exerted a novel antagonism of P-selectin and reduced complement deposition.

Investigation of Neutrophils in the Gut Lumen by Assay of Granulocyte Elastase in Whole-Gut Lavage Fluid

Intestinal neutrophils can be studied by radiolabelling techniques and by cytology of whole-gut lavage fluid. Our aim was to evaluate the use of a biochemical test for the presence of these cells in whole-gut lavage fluid. Whole-gut lavage was performed by having the patients drink a polyethylene-glycol-electrolyte solution; the clear fluid passed per rectum after complete bowel cleansing had been collected. In 203 patients granulocyte elastase was assayed in sonicated unfiltered lavage fluid, using the specific enzyme substrate L-pyroglutamyl-I-prolyl-L-valine-p-nitroanilide. Free granulocyte elastase was also assayed in filtered (that is, cell-free) lavage fluid in 39 of the 43 patients in whom the enzyme was present in unfiltered fluid. In 47 of the patients, cells were also separated by density gradient centrifugation, and counted. Granulocyte elastase concentration correlated significantly with cell count (r = 0.80, p < 0.001). Granulocyte elastase concentration was high (> 100 nkat/l) in fluid from 25 of 68 inflammatory bowel disease patients and 6 of 135 others with radiation colitis, diverticulitis, pericolic abscess, and use of non-steroidal anti-inflammatory drugs. In patients with detectable total granulocyte elastase, cell-free granulocyte elastase was present in 11 of 29 with inflammatory bowel disease and 1 of 10 others. Whole-gut lavage fluid samples can readily be used to investigate luminal inflammatory cells.

35] Galactose-specific adhesion mechanisms of Entamoeba histolytica: Model for study of enteric pathogens

This chapter discusses the evidence indicating that adhesion of Entamoeba histolytica is mediated by a galactose-inhibitable lectin and presents a method used to analyze the subunit structure of the adhesion protein. These investigations serve as a model to approach lectin–carbohydrate interactions of other pathogenic microorganisms. Adhesion to intestinal mucins, epithelium, and neutrophils is essential to the pathogenicity of E. histolytica. Initial efforts to characterize the nature of amebic adhesion focused on cell–cell interactions between amebic trophozoites and various target cells. The rosetting assay is described in the chapter in which Chinese hamster ovary (CHO) cells are bound by E. histolytica trophozoites and rosettes quantified in a hemacytometer chamber. Using the assay adhesion and contact-dependent cytolysis of CHO cells by trophozoites is shown to be completely blocked by millimolar concentrations of galactose and N-acetylgalactosamine (GalNAc), but not by other oligosaccharides, including N-acetylglucosamine, glucose, or mannose. In addition to adhesion, cell-contact dependent cytolysis has also been shown to be dependent on the galactose-inhibitable lectin using two different strategies. In the first, galactose or GalNAc is shown to inhibit amebic lysis of CHO cells completely. In the second approach, amebic binding and cytolysis of CHO cell glycosylation mutants are compared using cell-sorter methodology.

Endogenous Nitric Oxide Protects against Platelet-Activating Factor-Induced Bowel Injury in the Rat

Platelet-activating factor (PAF) causes bowel necrosis in animal models that is histologically identical to that seen in neonatal necrotizing enterocolitis, but little is known about endogenous mechanisms that might protect against PAF-induced bowel injury. We hypothesized that endogenous nitric oxide might represent such a protective mechanism. Adult male Sprague-Dawley rats were pretreated with 2.5 mg/kg NG-nitro-L-arginine methyl ester (L-NAME), a potent nitric oxide synthase inhibitor, and given injections of 1.5 micrograms/kg PAF 15 min later. Animals treated with normal saline placebo, L-NAME alone, and PAF alone were also studied. Superior mesenteric artery blood flow and blood pressure were continuously recorded. At the end of 2 h or upon death of the animal, hematocrit was measured and intestinal samples were taken for histologic examination and determination of myeloperoxidase activity, a measure of intestinal neutrophil content. Compared with animals given PAF alone, animals pretreated with L-NAME followed by PAF developed significantly worse bowel injury (median injury scores: 2.5 versus 0.5, p = 0.005), hemoconcentration (final hematocrit 65.2 +/- 2.0% versus 53.9 +/- 1.0%, p < 0.001), and intestinal myeloperoxidase activity (12.45 +/- 1.94 U/g versus 6.51 +/- 0.57 U/g, p < 0.01). The last two effects were further accentuated when 10 mg/kg L-NAME was given before PAF. Treatment with sodium nitroprusside, a nitric oxide donor, for 10 min before and after PAF administration reversed the effects of L-NAME. Animals pretreated with phenylephrine rather than L-NAME did not develop worse injury than animals treated with PAF alone despite comparable reductions in superior mesenteric blood flow before PAF treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Intestinal mast cells and neutrophil chemotactic activity of serum following a single challenge with gluten in celiac children on a gluten-free diet.

The number of one subtype of mast cells (formalin fixation, toluidine blue staining), cells of the lamina propria, and intraepithelial lymphocytes were counted in the intestinal biopsy specimens of 14 children with treated celiac disease following a single challenge with gluten. The serum neutrophil chemotactic activity was measured at 0, 1, 3, 5, and 24 h after challenge. There was no significant change in the number of intraepithelial lymphocytes, but the biopsy samples obtained at 5 h showed a marked increase in the inflammatory cells of the lamina propria and a significant decrease in the number of mast cells. A pronounced decrease was present at 3-5 h in the number of eosinophil cells in the blood. The neutrophil chemotactic activity of sera showed a significant increment in 10 of 14 patients. The intestinal permeability of patients became abnormal, as detected by the increased absorption of lactulose. These findings suggest that degranulation of mast cells may be involved in the pathogenesis of the small intestinal mucosal injury in children with celiac disease.

Intestinal Mast Cells and Neutrophil Chemotactic Activity of Serum Following a Single Challenge with Gluten in Celiac Children on a Gluten‐Free Diet

The number of one subtype of mast cells (formalin fixation, toluidine blue staining), cells of the lamina propria, and intraepithelial lymphocytes were counted in the intestinal biopsy specimens of 14 children with treated celiac disease following a single challenge with gluten. The serum neutrophil chemotactic activity was measured at 0, I, 3, 5, and 24 h after challenge. There was no significant change in the number of intraepithelial lymphocytes, but the biopsy samples obtained at 5 h showed a marked increase in the inflammatory cells of the lamina propria and a significant decrease in the number of mast cells. A pronounced decrease was present at 3–5 h in the number of eosinophil cells in the blood. The neutrophil chemotactic activity of sera showed a significant increment in 10 of 14 patients. The intestinal permeability of patients became abnormal, as detected by the increased absorption of lactulose. These findings suggest that degranulation of mast cells may be involved in the pathogenesis of the small intestinal mucosal injury in children with celiac disease.