Intestinal immunity and inflammation: recent progress

Desloratadine via its anti-inflammatory and antioxidative properties ameliorates TNBS-induced experimental colitis in rats

BACKGROUND

Intestinal mucosal immune cells, notably mast cells, are pivotal in ulcerative colitis (UC) pathophysiology. Its activation elevates tissue concentrations of histamine. Inhibiting colonic histamine release could be an effective therapeutic strategy for treating UC. Experimental model like 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats mimic human IBD, aiding treatment investigations. Drug repurposing is a promising strategy to explore new indications for established drugs. Desloratadine (DES) is second-generation antihistamine utilized for managing allergies by blocking histamine action in the body. It also has reported anti-inflammatory and antioxidant actions.

OBJECTIVE

DES was investigated for its repurposing potential in UC by preclinical screening in TNBS-induced colitis in Wistar rats.

METHODS

Therapeutic efficacy of DES was evaluated both individually and in combination with standard drug 5-aminosalicylicacid (5-ASA). Rats were orally administered DES (10 mg/kg), 5-ASA (25 mg/kg), and DES + 5-ASA (5 mg + 12.15 mg) following the induction of colitis. Parameters including disease activity score rate (DASR), colon/body weight ratio (CBWR), colon length, diameter, pH, histological injury, and scoring were evaluated. Inflammatory biomarkers such as IL-1β, TNF-α, along with reduced glutathione (GSH), and malondialdehyde (MDA) were assessed.

RESULTS

Significant protective effects of DES, especially in combination with 5-ASA, against TNBS-induced inflammation were observed as evidenced by reduced DASR, CBWR, and improved colon morphology. Drugs significantly lowered plasma and colon histamine and, cytokines levels. GSH restoration, and decreased MDA content were also observed.

CONCLUSION

DES and DES + 5-ASA demonstrated potential in alleviating colonic inflammation associated with TNBS-induced colitis in rats. The effect can be attributed to its antihistamine, anticytokine, and antioxidative properties.

Microencapsulated subunit vaccine approach to enterotoxigenic Escherichia coli and other mucosal pathogens

Infections of the intestinal, urogenital, and respiratory tracts are serious health problems worldwide from both a morbidity and mortality perspective. Mucosal pathogens attach to surfaces of mucosa as a prerequisite for colonization and subsequent pathogenesis. By expressing various surface adhesins (colonization factors, CF) they are able to bind to specific mucosal receptors. Enterotoxigenic Escherichia coli (ETEC) can express numerous CF that allow them to attach to a variety of hosts. Mucosal immunity directed against pathogenic microorganisms is critical in host protection with secretory IgA being particularly important in preventing microoganisms from colonizing host cells. M cells likewise have an important immunological function in the small intestines by binding and transporting antigens to lymphocytes and macrophages thus enhancing the immune response. The use of subunit vaccines, such as antigen encapsulated microspheres, can act to effectively deliver specific antigens so as to optimize their immunological response. With the threat of bioterrorism becoming a reality in recent years, the miroencapsulation of antigens from potential bioterrorist agents may be an effective method of delivery so as to induce a level of protection in at risk individuals. The encapsulation of ETEC colonization factors in microspheres and their subsequent administration in small animals and humans has been conducted for many years. Evidence suggests that this type of delivery system for ETEC antigens may enhance their immunogenicity and provide protection against this microorganism.

Immunophysiology of enteric parasitism

Capron and Dessaint have described the relationship between parasites and their hosts in terms of 'cell sociology'. In this review Gilbert Castro discusses the 'sociological' aspects of functional associations among cells comprising the hollow organs of the gastrointestinal tract and the influence on them of enteric parasitism, and shows how such cells and tissues work in an integrated fashion to help the whole organism to maintain homeostasis under the stress of parasitic invasion.

Pathology of colorectal cancer

The earliest phases of colorectal tumourigenesis initiate in the normal mucosa, with a generalised disorder of cell replication, and with the appearance of clusters of enlarged crypts (aberrant crypts) showing proliferative, biochemical and biomolecular abnormalities. The large majority of colorectal malignancies develop from adenomatous polyps. These can be defined as well demarcated masses of epithelial dysplasia, with uncontrolled crypt cell division. An adenoma can be considered malignant when neoplastic cells pass through the muscularis mucosae and infiltrate the submucosa. Definitions like "carcinoma in situ" or "intramucosal carcinoma" should be abandoned, since they lead to confusion. Although several lines of evidence indicate that carcinomas usually originate from pre-existing adenomas, this does not imply that all polyps undergo malignant changes, and does not exclude "de novo" carcinogenesis. Besides adenomas, other types of polypoid lesions include hyperplastic polyps (showing elongated crypts often with cystic dilatation), serrated adenomas (with a serrated glandular pattern], flat adenomas (flat lesions which are difficult to detect in routine lower endoscopy, but may possess malignant potential), hamartomatous polyps (which show a complex branching pattern of smooth muscle supporting normal lamina propria and glands), and inflammatory polyps. Colorectal carcinomas are one of the most frequent neoplasms in Western society; the macroscopic appearance of these lesions may be that of a polypoid vegetating mass or of a flat infiltrating lesion. Most of these tumours are adenocarcinomas (96%), that, in some cases, show a mucinous component. More rare malignancies of the large bowel include signet-ring cell carcinoma, squamous carcinoma, undifferentiated neoplasms and medullary type adenocarcinoma (solid carcinoma with minimal glandular differentiation or slight cellular pleomorphism). Colorectal carcinoma can be graded into well, moderately and poorly differentiated lesions; there is little evidence, however, that grading may be of help in evaluating prognosis of affected patients. In conclusion, colorectal tumours cover a wide range of premalignant and malignant lesions, many of which can easily be removed at endoscopy. It follows that colorectal neoplasms might be prevented by interfering with the various steps of carcinogenesis, which begins with uncontrolled epithelial cell replication, continues with the formation of adenomas of various dimensions, and eventually evolves into malignancy.

Secretion and tissue content of eosinophil cationic protein in Crohn's disease

To define further the role of eosinophils in the pathogenesis of Crohn's disease, the secretion rate and tissue content of eosinophilic cationic protein (ECP) were measured in colorectal samples. Mucosal biopsies were obtained from 22 controls and 20 patients with Crohn's disease during colonoscopy. After measurement of the initial basal ECP, release samples were incubated using a mucosa oxygenation system. Spontaneous and antiimmunoglobulin E (anti-IgE)-induced secretions of ECP were measured at different time points. For detection of the remaining tissue, ECP amount samples were mechanically homogenized after the incubation period. ECP measurement was performed by radioimmunoassay. Spontaneous ECP secretion rates during the incubation period were similar in all patient groups, whereas the initial basal ECP secretion was significantly increased in tissue affected by Crohn's disease. After stimulation with anti-IgE, ECP secretion was increased two-fold in controls and three-fold in patients with Crohn's disease. In tissue affected by Crohn's disease, ECP levels were found to be significantly increased in most segments of the lower gastrointestinal tract with the highest ECP concentrations in affected mucosa. This functional study demonstrates an enhanced immunologically mediated ECP secretion and an accumulation of ECP in the intestinal mucosa of Crohn's disease, indicating a local upregulation of eosinophils.

Low-level exposure to diquat induces a neurally mediated intestinal hypersecretion in rats: involvement of nitric oxide and mast cells

Diquat, a nonselective desiccant herbicide, induces a significant secretion of fluid into the lumen of the gastrointestinal tract of rats at sublethal doses (from 0.5 to 50 mg/kg). This study investigated the effect of an acute low-level exposure to diquat (0. 1, 0.5, and 1 mg/kg) on intestinal net water flux and the mechanisms involved. In anesthetized rats, an intestinal loop (7 cm) was infused with Ringer's buffer containing [14C]-polyethylene glycol 4000. After equilibration, diquat (0.1, 0.5, and 1 mg/kg) was added to Ringer's buffer during 60 min. Net water flux was calculated according to [14C] activity determined in the effluent collected at 15-min intervals. Infused in the intestinal loop for 60 min at doses of 0.5 and 1 mg/kg but not at 0.1 mg/kg, diquat induced an intestinal net water secretion during 180 min with a maximal effect at the highest dose used and during the first hour following the end of diquat infusion. Diquat-induced (1 mg/kg) intestinal net water secretion was blocked by a neurotoxin, tetrodotoxin (5 micrograms/kg iv), doxantrazole (5 mg/kg ip), a mast cell stabilizer, and two inhibitors of NO synthases: l-NAME (25 mg/kg ip) and aminoguanidine (2 mg/kg ip). It is concluded that a single low-level (0.5 and 1 mg/kg) intrajejunal administration of diquat induces a net water intestinal secretion and that this secretory effect is nerve-mediated, implying mast cell degranulation and NO release.

Analysis of cytokine profile in human colonic mucosal Fc epsilonRI-positive cells by single cell PCR: inhibition of IL-3 expression in steroid-treated IBD patients

Mast cells can serve as a possible important source of cytokine production in inflamed tissue which can be regulated by stimuli different from those activating other immune system cells. To study the expression of specific genes in mast cells derived from small human colonic mucosal endoscopic biopsies, we first modified a previously reported procedure to achieve a significantly enriched mast cell fraction. Then, by using single-cell RT-PCR analysis the expression of the IgE Fc receptor (Fc epsilonRI) and c-kit mRNA was determined. It was observed that the Fc epsilonRI-positive cells also expressed c-kit. This observation provided further evidence that Fc epsilonRI-positive cells are indeed mast cells. Analysis of biopsies from 12 patients (four control and eight patients with inflammatory bowel disease (IBD)) was carried out, revealing that all of the Fc epsilonRI-positive cells expressed IL-3, while the expression of IL-4 was detected only in some of these positive cells. TNF alpha was not detected in these cells. Therefore, it would seem that most intestinal mast cells produce IL-3. Since it has been reported that IL-3 synthesis was down-regulated in steroid-treated cells, the expression pattern of IL-3 in intestinal mast cells derived from steroid-treated IBD patients was then determined. IL-3 mRNA was detected in only two out of 24 Fc epsilonRI-positive cells derived from these steroid-treated patients. These results lend strong support to the idea that the down-regulation of IL-3 in mast cells derived from steroid-treated IBD patients occurs in vivo and could be an important mechanism for immunomodulation in IBD.

Substance P--an underlying factor for pouchitis? Prospective study of substance P- and vasoactive intestinal polypeptide-immunoreactive innervation and mast cells

Recent studies suggest that substance P (SP), vasoactive intestinal polypeptide (VIP), and mast cells play a role in inflammatory processes of the bowel. The aim of this study was to evaluate the distribution of SP and VIP immunoreactivities and to count mast cells in the ileal pouch of patients, who had pouchitis after restorative proctocolectomy performed for treatment of ulcerative colitis (UC), and to compare the findings in the same patients after a follow-up period. Nine patients with pouchitis underwent clinical evaluation, endoscopy of the pouch, and histological examination, which were repeated after the follow-up period of 14 months on average. The number and intensity of SP- and VIP-immunoreactive nerve fibers were visualized by immunofluorescence microscopy and subjected to quantitative scoring, and the number of mast cells per unit area was counted. The results were compared to the histological findings and the clinical status. Lamina propria contained fibers showing bright immunofluorescence for SP and VIP. The mean fluorescence intensity score of SP-immunoreactive nerve fibers in the lamina propria remained similar after the follow-up period (2.99 +/- 0.79 and 2.06 +/- 0.82, NS). SP-immunoreactive innervation correlated with the grade of acute (R2 = 0.5396, P = 0.0242) and chronic inflammation (R2 = 0.4561, P = 0.0459), while SP and VIP immunoreactivity, mast cell count, and histological changes did not correlate with the clinical status. The present study demonstrates an increase in the density of SP-immunoreactive nerve fibers in inflamed ileal pouch mucosa of clinically asymptomatic pouchitis patients. These results raise the possibility of therapeutic interference of SP-related processes in treatment of pouchitis.

Substance P- and vasoactive intestinal polypeptide-immunoreactive innervation in normal and inflamed pouches after restorative proctocolectomy for ulcerative colitis

Recent studies suggest that the intestinal polypeptides substance P (SP) and vasoactive intestinal polypeptide (VIP) play a role in the bowel inflammatory processes. The aim of this study was to evaluate the distribution of SP and VIP immunoreactivities in the ileal pouch of the patients with ulcerative colitis (UC). Thirty-six patients underwent clinical evaluation, endoscopy, and histological examinations. Samples were taken from normal ileum (N = 9), ileum of UC patients (N = 9), normal ileal pouch (N = 9) and pouchitis (N = 9). SP- and VIP-containing nerve fibers were visualized in sections processed for immunofluorescence microscopy. The number and intensity of SP and VIP immunoreactivities were subjected to quantitative scoring. On samples from all groups lamina propria contained fibers showing bright immunofluorescence for SP and VIP. The number and intensity of SP immunoreactive nerve fibers were markedly increased in pouchitis as compared to normal pouch (P < 0.005), to ileum of UC patients (P < 0.001), and to normal ileum (P < 0.05). The number and intensity of VIP-immunoreactive nerve fibers in the lamina propria were markedly increased in pouchitis patients and in those having a normal pouch as compared to pooled values of ileum of UC patients and normal ileum (P < 0.05). The results suggest that SP, which may play a role in mediating inflammatory processes, is increased in pouchitis and that VIP, which may contribute to the regulation of intestinal motility, is increased in the pouch.

Development of immune function in the intestine and its role in neonatal diseases

This review has traced the ontogeny of the human mucosal immune system, speculating that appropriate gut immune responses are essential in preventing many significant neonatal enteric diseases. Because the gastrointestinal tract serves as the portal of entry for many potential antigens, its mucosal immune function is essential in controlling antigenic responses and ensuring systemic tolerance. A thorough under standing of the development of the entire immune system is essential in defining intestinal mucosal immune function. From the protective barrier covering the enterocyte to the intraepithelial T lymphocytes, these components work together to limit antigen passage from the gut lumen to the underlying immune cells and, thus, promote normal immunity and tolerance. When abnormalities exist or when this immune barrier has not matured fully, conditions afflicting newborns, especially preterm infants, occur. Necrotizing enterocolitis, milk-protein enteropathy, and enteric bacterial infections are only three clinical examples of how aberrant gut immune-mediated defenses may have a significant role in their pathogenesis. In clinical practice, it is not only important to recognize these conditions at their onset but also to understand the basis for the underlying illness and identify newborns who are at an increased risk of acquiring them.

Changes in substance P-immunoreactive innervation of human colon associated with ulcerative colitis

The amount of colonic substance P and substance P-receptors is increased in ulcerative colitis, which may denote that substance-P is involved as a neurogenic mediator in the inflammatory process of ulcerative colitis. We studied the anatomical distribution of elevated colonic substance P in ulcerative colitis and assessed morphometrically whether the changes in substance P correlate with alterations in colonic innervation. Full-thickness specimens of colonic wall were obtained from normal human colons (N = 9) and the most and least affected regions of ulcerative colitis colons (N = 10) and immunostained for substance P. Substance P immunoreactivity index was calculated by multiplying each intensity value by the number of pixels exhibiting this intensity value. The numbers of substance P-immunoreactive nerve fibers in the lamina propria were markedly increased, and their fluorescence intensity was enhanced in ulcerative colitis. The longitudinal muscle layer contained substance P-immunoreactive nerve fibers in ulcerative colitis, but not in the controls. The substance P-immunoreactive index (= number x intensity of nerve fibers) was 3.42 +/- 1.49 in controls, 21.19 +/- 7.79 in mild ulcerative colitis regions (P < 0.05), and 29.68 +/- 9.81 in severe ulcerative colitis regions (P < 0.01). Increase in the number of substance P nerve fibers is in accordance with the hypothesis that substance P contributes to neurogenic mediation of inflammation in ulcerative colitis.

Uptake of antigens: role in gastrointestinal disease

The intestine is exposed to a wide variety of macromolecules. Because macromolecules are antigenic, mechanisms have evolved in the gastrointestinal tract to regulate their absorption. Macromolecular uptake can be beneficial in delivering essential factors for growth and in sampling the antigenic milieu of the gastrointestinal tract. Specific transport mechanisms exist to execute this physiological absorption. However, inappropriate and uncontrolled antigen transport may occur in disease states, or as a prelude to disease states in the gastrointestinal tract. Such transport may result in immune responses that are harmful. In this review we examine both physiological transport of macromolecules through epithelia and through M cells. We also discuss uncontrolled transport and its relation to disease states. We conclude by examining the interrelationship between antigen transport and an altered immune system in the establishment of gastrointestinal disease.

T cell cytotoxicity of autologous and allogeneic lymphocytes in a patient with Crohn's disease

We report a 27-year-old male with Crohn's disease (CD) of the small and large intestine, whose peripheral blood lymphocytes (PBL) showed increased cell-mediated cytotoxicity (CTL). Autologous and allogeneic effector cells from PBL and intestinal lymph nodes (LN) were isolated on a Ficoll-Hypaque gradient. Colonic cells were prepared as the target and were incubated for 6h with effector cells, after being labeled with Na(2)51CrO4. The CTL activity [effector/target (E/T) ratio, 100:1] of PBL for autologous targets was increased by 38% compared with that in normal subjects (< 10%), while that shown by LN was not increased (14%). The CTL activity of allogeneic PBL prepared from three of four other CD patients was also increased. Anti-major histocompatibility (MHC) class I and II and CD4 and CD8 monoclonal antibodies (50 micrograms/ml) significantly inhibited CTL activity. Complement-mediated depletion of CD2+ cells significantly reduced CTL activity. These results suggest that MHC-restricted CTL may play a role in mucosal damage in some patients with Crohn's disease.

Major histocompatibility antigen-restricted cytotoxicity in inflammatory bowel disease

BACKGROUND

The role of cytotoxicity mediated by peripheral blood mononuclear cells for colonic epithelial cells in inflammatory bowel disease (IBD) is still controversial. To clarify it, we studied major histocompatibility antigen (MHC)-restricted T cell-mediated cytotoxicity (CTL).

METHODS

Cytotoxicity was measured by 51Cr release from colonic cells after the 6-hour incubation with peripheral blood mononuclear cells in 11 IBD patients (6 with Crohn's disease and 5 with ulcerative colitis).

RESULTS

CTL activity (E/T ratio = 200:1 or 100:1) for autologous target cells was significantly increased (22%-40%) in 5 of 6 CD and 4 of 5 UC patients (22%-64%) compared with that for allogeneic target cells. The increase in CTL activity was mainly inhibited by anti-MHC class I and CD8 monoclonal antibodies (50 micrograms/mL), while it was partially inhibited by anti-MHC class II or CD4 antibodies in some patients. Complement-mediated depletion of CD2+ cells also significantly decreased CTL activity.

CONCLUSIONS

The results indicate that MHC-restricted T cell cytotoxicity may play a role in mucosal damage in some patients of IBD.

Uptake and transport of macromolecules by the intestine: possible role in clinical disorders (an update)

The intestine is exposed to a wide variety of macromolecules. Because macromolecules are antigenic, mechanisms have evolved in the gastrointestinal tract to regulate their absorption. Macromolecular uptake can be beneficial in delivering essential factors for growth and in sampling the antigenic milieu of the gastrointestinal tract. Specific transport mechanisms exist to execute this physiological absorption. However, inappropriate and uncontrolled antigen transport may occur in disease states or as a prelude to disease states in the gastrointestinal tract. Such transport may result in immune responses that are harmful. This review examines physiological transport of macromolecules through epithelia and through M cells. It also considers uncontrolled transport and its relation to disease states. The review concludes with an examination of the interrelationship between antigen transport and an altered immune system in the establishment of gastrointestinal disease.

A model of inflammatory bowel disease induced by 2,4-dinitrofluorobenzene in previously sensitized BALB-c mice

The aim of this study was to develop a model of inflammatory bowel disease (IBD) induced by colonic application of 2,4-dinitrofluorobenzene in previously sensitized BALB-c mice. During the follow-up period of 30 days we observed ulcerations, haemorrhage, necrosis, and mononuclear infiltration in the colonic mucosa of previously sensitized (experimental) and, to a lesser extent, nonsensitized (control) animals. In addition, the animals in the experimental group developed adhesions, thickening of colonic segments, stenosis, and dilatation of the colon, and some animals also developed megacolon. Oedema, mononuclear infiltration, and superficial ulcerations were observed in the ileum of experimental animals and, to a lesser extent, in the control group. In addition, the animals in the experimental group developed extraintestinal changes in the liver and spleen (that is, pericholangitis and lymphofollicular proliferation). We suggest that this model of IBD may have some value for the study of early pathogenetic mechanisms of IBD and for developing new therapeutic modalities for this condition.

Protein malnutrition alone and in combination with endotoxin impairs systemic and gut-associated immunity

Because protein-malnourished or endotoxemic patients are at an increased risk of developing nosocomial infections, this study was performed to investigate the effects of protein malnutrition and endotoxemia, alone and in combination, on systemic and intestinal immunity. Protein malnutrition was created by feeding the animals a solid diet containing 0.03% protein. Subgroups of these protein-malnourished mice were killed after being challenged with saline or endotoxin on days 0, 7, 14, or 21. At death, the animals were weighed, tissues were harvested for histologic analysis (ileum, mesenteric lymph node [MLN], liver, and spleen), mitogen responsiveness (MLN, Peyer's patches, and spleen), and xanthine oxidase measurements (ileum and cecum). Separate groups were evaluated for survival. Both the saline and endotoxin-challenged mice had lost about 30% of their body weight after 21 days on the low-protein diet. The protein-malnourished mice were more susceptible to endotoxin-induced mortality (70% at 21 days) than the normally nourished mice (0%) (p less than .001). The mitogen responsiveness of the protein-malnourished mice to the T-cell mitogens (PHA and Con-A) progressively decreased the longer the mice were protein malnourished, and this decreased in blastogenic responsiveness was associated with histologic evidence of lymphoid atrophy. In contrast, the blastogenic response to the primarily B-cell mitogen, PWM, was largely preserved. The endotoxin challenge further depressed the immune state of mice tested after 0, 7, or 14 (but not 21) days of protein malnutrition. Thus, both protein malnutrition and endotoxin impaired systemic and gut-associated immune responsiveness to mitogens. However, in the protein-malnourished mice, the degree of immune suppression did not correlate with endotoxin-induced mortality.

Intestinal lymphokine-activated killer cells in inflammatory bowel disease

The role of non-specific cytotoxicity in the pathogenesis of inflammatory bowel disease (IBD) was investigated by assaying the natural killer (NK) and lymphokine-activated killer (LAK) cell activity of lamina propria mononuclear cells (LPMC) from 22 specimens of intestinal mucosa affected by IBD. Only minimal levels of NK activity were detected against K562 cells, as well as colon carcinoma cells, adenoma cells and fibroblasts freshly isolated from the intestinal mucosa. Culture of LPMC from IBD in the presence of interleukin-2 (IL-2) generated LAK cells that mediated high levels of activity against K562 cells and against neoplastic epithelial cells and fibroblasts derived from the intestinal mucosa. A group of 20 histologically normal specimens of intestinal mucosa showed similar levels of LAK activity against the K562 and intestinal cell targets. The minimal mucosal NK activity in IBD suggests that the cytotoxic properties of NK cells are not important in the pathogenesis of IBD. The presence of LAK precursor cells in the inflamed mucosa of IBD and their ability to lyse biologically relevant targets in vitro suggests that LAK cells have the potential to contribute to intestinal mucosal injury in IBD.

Beta-casomorphin (BCM) and human colonic lamina propria lymphocyte proliferation

BCM is a milk-derived peptide with opiate-like properties which is absorbed through the gastrointestinal mucosa. It has been shown to affect gastrointestinal motility, absorption and secretion. Recently, modulation of the immune system by BCM was also reported. In this study we investigated the in vitro effect of BCM on the human mucosal immune response as represented by lamina propria lymphocyte (LPL) proliferation. Results show that BCM significantly inhibited concanavalin A (ConA) stimulated LPL DNA synthesis. BCM also inhibited ornithine decarboxylase activity (ODC) in ConA-stimulated LPL. Although BCM also inhibited 12-O-tetradecanoyl phorbol-13-acetate (TPA) stimulated LPL DNA synthesis, the degree of inhibition was much lower than in ConA-stimulated LPL. The anti-proliferative effect of BCM was reversed by the opiate receptor antagonist, neloxone. Our results suggest that BCM may affect the human mucosal immune system, possibly via the opiate receptor.

Mononuclear cells in peripheral venous blood of patients with Crohn's disease: preoperative status and postoperative course, influence of duration, activity and extent of disease

In Crohn's disease (CD) the intestinal lesion is supposed to be the cause of the observed systemic immunologic changes. Based on this assumption, peripheral blood mononuclear cells (PBMC) are of specific interest as a possible indicator of intestinal activity of the disease. From 151 surgical patients CD3+, CD4+, CD8+, B cells, macrophages, leucocytes and the relative number of lymphocytes were analysed preoperatively and 10 days, 3 and 6 months postoperatively. The cell data were correlated with the main clinical data of disease. There was a highly significant preoperative increase of leucocytes, macrophages, CD8+, and B cells in the CD group, and a marked decrease of CD3+, CD4+ cells, and the relative lymphocyte count in the same group. Six months postoperatively, highly elevated macrophages, and leucocytes, and a depressed number of CD4+ cells were the only changes. The preoperative cell data did not correlate with the duration of illness, CDAI, localisation, and extent of the intestinal lesion nor did they correlate with any modality of preoperative drug treatment. Thus, the determination of PBMC characteristics in CD is only of limited value for routine diagnostic purposes. However, the persistence of some pathological values long after operation might be caused by residual microscopic lesions and thus reflect the intestinal process.

Reactive oxygen metabolites and colitis: a disturbed balance between damage and protection. A selective review

Enhanced local production of reactive oxygen metabolites has been found in association with colitis, both experimentally and in humans. Cellular and biochemical systems involved have been identified, and 5-aminosalicylic acid-containing drugs but, more effectively, specific scavengers have been found to reduce the intestinal inflammatory process. The multitude of reactions in which oxygen metabolites participate provides a new area of research in intestinal inflammation. These basic studies might bring related clinical studies in an era of new anti-inflammatory drugs for inflammatory bowel disease specifically designed to scavenge toxic oxygen metabolites.

Giant inflammatory polyps associated with idiopathic inflammatory bowel disease. An ultrastructural study of five cases

Five cases of giant inflammatory polyps associated with idiopathic inflammatory bowel disease are reported. Polyps produced intestinal obstruction in three cases; consequently, surgery was performed. In a further two cases, intestinal bleeding was improved by endoscopic polypectomy. Electron microscopy showed fibroblasts, myofibroblasts, mast cells, lymphocytes, collagen fibers, capillaries, and venules. Remnants of the original mucosal epithelial cells, smooth muscle cells, and hypertrophic autonomous nerve plexuses were noted. Nerve fibers were interwoven with the matrix of the polyps. Mast cells were closely linked with vessels, nerves, and collagen fibers. They may have an important role in the excessive granulation, angiogenesis, and fibrotic process in giant inflammatory polyps.

Histochemical and ultrastructural characteristics of rat brain perivascular mast cells stimulated with compound 48/80 and carbachol

Mast cells, known for their involvement in allergic reactions where they secrete numerous chemicals in response to immunoglobulin E and specific antigens, have recently been localized in the central nervous system. The function of these brain mast cells has remained speculative as they have not been the subject of any combined functional or detailed morphological studies. Here it is shown that these cells are primarily perivascular and stain metachromatically with Toluidine Blue, but red with Alcian Blue counterstained with Safranin, indicating that they contain proteoglycans quite similar to those of peritoneal, but not mucosal mast cells. Intracardiac administration of the classic mast cell secretagogue, compound 48/80, or the acetylcholine analog, carbachol, caused ultrastructural changes in brain mast cells consistent with secretion, but without exocytosis. However, it is known that the same concentration of carbachol has no effect on homogeneic peritoneal mast cells. These results indicate that brain mast cells share histochemical characteristics with serosal mast cells, but differ in their reactivity to secretagogues, and apparently in the mechanism of secretion. Their ability to respond to neurotransmitters and their distinct mechanism of secretion, which may be selective, expands their possible role in brain pathophysiology.

Immune events associated with inflammatory bowel disease

Immunologic abnormalities have been implicated in the etiology of inflammatory bowel disease (IBD). Defects of systemic immunity and of local (intestinal) immunity have been studied. The numbers of T and B lymphocytes and their characteristics seem to vary with the disease, but no cause-and-effect relationship has been established. The presence of anticolon antibodies in patients with ulcerative colitis suggests that these antibodies could be involved in IBD, but they have also been found in other conditions. In the peripheral blood, abnormalities of cell-mediated immunity are inconsistent and suggest that they are not fundamental defects of the disease. The hypothesis that the inflammatory process is a result of immune-mediated intestinal tissue damage is being extensively studied. The high familial incidence of the disease suggests a role of histocompatibility locus antigens, but no reproducible association can be established. In vivo and in vitro studies of mucosal mononuclear cells have revealed abnormalities of immunoglobulin production, some types of cytotoxicity against gut-derived antigens, and altered lymphokine production associated with the disease. Further studies of the intestinal immune system would seem to be the most fruitful line of research.

Medical management of inflammatory bowel disease

Inflammatory bowel disease is a serious ailment that afflicts nearly one million people in the U.S. alone. The medical management of this disorder currently includes salicylates, corticosteroids, immunosuppressive therapy, and symptomatic treatment with antidiarrheal agents, although several promising new drugs have been developed. The epidemiology, etiology, pathogenesis, and medical management of the disease are discussed in this article.

Expression of immune sensitization to epithelial cell-associated components in the cotton-top tamarin: a model of chronic ulcerative colitis

Chronic colitis is present in up to 50% of adult cotton-top tamarins, but the etiology is unknown. To explore one putative immunopathogenic pathway for the chronic colitis, we determined whether immune sensitization to macromolecules associated with mucosal epithelium of intestine (designated ECAC) had occurred in this primate species. Specifically, we sought to define (a) whether antigenic determinants associated with ECAC are present on tamarin gut epithelium in vivo; (b) if immunoglobulin, capable of binding ECAC, is detectable in tamarin serum; (c) whether the presence of ECAC-specific immunoglobulin is positively correlated with age of the animal or the severity of the colitis, or both; and (d) the number of glycoprotein fractions composing ECAC (denoted as P1 through P4) that are reactive with tamarin immunoglobulin. Expression of ECAC was found by immunofluorescence using characterized oligo-specific or monoclonal antibody: tamarin intestinal epithelium--but not lamina propria, muscularis mucosae, subserosa, or glycocalyx--demonstrated determinants of the ECAC antigen system. Furthermore, coded sera from 10 tamarins with biopsy-proven inflammation involving colonic intestinal mucosa and in which disease activity was moderate to severe showed ECAC-specific cytotoxicity of 3.6% +/- 1.6%. Test values for 9 of 10 of those animals were above the upper limit of normal for the assay (2.1%), and exceeded the level of lysis found with serum from histologically normal tamarins less than 2 yr old (less than 0.3%). When the data were reanalyzed by age of the animal, the incidence of ECAC-specific cytotoxicity correlated with age greater than 2 yr (r = 0.86, p less than 0.001). Epithelial cell-associated component-specific serum binding was confirmed by a second methodology (enzyme-linked immunosorbent assay), where the A405 for tamarins with lesions of moderate-severe grade (0.35 +/- 0.26) clearly exceeded that for young tamarins who were histologically normal (0.02 +/- 0.039) (p less than 0.05). Most of the reactivity was directed toward the P1 fraction of ECAC. Thus, immune sensitization to a fraction of macromolecules associated with colonic epithelium has been found in the cotton-top tamarin, analogous to findings in humans with chronic inflammatory bowel disease.

Inflammatory mediators of experimental colitis in rats

Colonic inflammation was induced in rats by intracolonic administration of 0.25 ml of 50% ethanol containing 30 mg of trinitrobenzene sulfonic acid (TNB). Control rats were treated with 0.25 ml of 50% ethanol or with 30 mg of TNB in 0.25 ml of saline. After 24 h, mucosal ulceration and hemorrhage were observed in TNB/ethanol-, 50% ethanol-, and to a lesser extent, in TNB/saline-treated rats. After 1 wk, mucosal damage was completely resolved in the 50% ethanol and TNB/saline-treated rats but the lesions in the TNB/ethanol-treated rats persisted and progressed to a chronic active inflammatory process after 3 wk. Myeloperoxidase activity was significantly elevated in mucosal scrapings from all treatment groups at all time intervals when macroscopic and microscopic mucosal injury was evident. Interleukin-1 was found to be the most sensitive indicator of mucosal inflammation, and its mucosal values correlated with myeloperoxidase activity. Leukotriene B4 was increased in control rats at 1 wk and in TNB/ethanol-treated rats at all time intervals. The maximal increase in leukotriene B4 was observed at 1 wk. Thromboxane B2 generation was reduced while platelet activating factor generation was not increased in TNB/ethanol-treated rats. These results indicate that in this TNB/ethanol model of gut inflammation, myeloperoxidase activity and interleukin-1 are reliable and sensitive indicators of colonic inflammation, and that thromboxane B2 is not involved in the acute lesions, whereas leukotriene B4 appears in the chronic active inflammatory response.

Immune system control of rat and rabbit colonic electrolyte transport. Role of prostaglandins and enteric nervous system

The role of the immune system in controlling intestinal electrolyte transport was studied in rat and rabbit colon in Ussing chambers. A phagocyte stimulus, the chemotactic peptide FMLP, and a mast cell stimulus, sheep anti-rat IgE, caused a brief (less than 10 min) increase in short-circuit current (Isc). Products of immune system activation, platelet-activating factor (PAF) and reactive oxygen species (ROS), caused a sustained, biphasic increase in the Isc. Ion replacement and flux studies indicated that these agonists stimulated electrogenic Cl secretion and inhibited neutral NaCl absorption; responses that were variably inhibited by the cyclooxygenase blockers indomethacin and piroxicam. Lesser degrees of inhibition by nordihydroguaiaretic acid could be accounted for by decreased prostaglandin synthesis rather than by lipoxygenase blockade. Tetrodotoxin, hexamethonium, and atropine also inhibited immune agonist-stimulated Isc, but had no effect on immune agonist-stimulated production of PGE2 or PGI2. These results indicate that immune system agonists alter intestinal epithelial electrolyte transport through release of cyclooxygenase products from cells in the lamina propria with at least 50% of the response being due to cyclooxygenase product activation of the enteric nervous system. The immune system, like the enteric nervous system and the endocrine system, may be a major regulating system for intestinal water and electrolyte transport in health and disease.

Mucosal IgA elaboration

Secretory IgA is the main immunoglobulin present along mucosal surfaces. It is elicited best by oral rather than parenteral administration of specific antigens. The role of antigen form on the development of a secretory IgA response is still unclear. IgA protects by preventing attachment of microorganisms or their toxic products to the surface epithelium. A wide variety of regulatory T cells are now known to be of considerable importance in optimizing the secretory IgA response. This regulation is at least partly due to the elaboration of small polypeptide products (lymphokines). These lymphokines have been shown to be key signals during the maturation of IgA precursor B cells to IgA-secreting plasma cells. By studying models of the mucosal immune system which closely approximate the natural mucosal immune response, it should be possible to develop vaccines against many pathogenic microorganisms, their toxic products, and to toxicants and carcinogens within the environment.

Kinetics of mast cells, eosinophils and phospholipase B activity in the spontaneous-cure response of two strains of mice (rapid and slow responder) to the cestode Hymenolepis nana

Primary egg-derived infection of Hymenolepis nana (100 eggs) in BALB/c (rapid responder) and C3H (slow responder) mice resulted in increased levels of mucosal mast cells (MMCs), eosinophilia (bone marrow, peripheral, tissue) and phospholipase B activity. The response appeared to be similar in both strains used, with a slight difference in cellular accumulation but a significantly earlier response in BALB/c than in C3H mice. These findings suggest that the prolongation of H. nana infection in C3H mice may be related to the delayed appearance of MMCs and eosinophils, which triggers a slower generation of the intestinal inflammation response. The rapidity with which phospholipase B activity increased was strictly correlated with eosinophil tissue number; this further supports the hypothesis for a direct parallel between eosinophils and phospholipase B activity in infected tissue.

Mast cells in ulcerative colitis. Quantitative and ultrastructural studies

The changes in the number and ultrastructure of mast cells were studied in 37 colonoscopical biopsies from patients with ulcerative colitis. Changes in the active stage of the disease and during remission were compared. Cell counts were performed on semithin sections stained with Giemsa after osmium tetroxide fixation. This method overcome the uncertain staining found after formalin fixation. Accumulation of mast cells accompanied by intense degranulation was found to be significant in the active stage of the disease. Two forms of degranulation were observed: discharge of the individual granules and protrusion and detachment of the cytoplasmic processes containing granules. The latter was a sign of rapid degranulation, as described earlier in animal experiments. Mast cells were closely associated with capillary blood vessels, Schwann cells, neural fibres, myofibroblasts and collagenous fibres, and were also present between epithelial cells. It is assumed that close topographic contact may also imply a functional correlation.

Enhanced peripheral blood T-cell cytotoxicity in inflammatory bowel disease

Monoclonal antibodies to the CD3 component of the T-cell antigen receptor can trigger antigen-specific cytotoxic T cells to elicit nonantigen-specific cytotoxicity, possibly by mimicking or bypassing the requirement for antigen triggering. We have used this technique to investigate the possible presence of in vivo primed cytotoxic T cells, of unknown antigen specificity, in peripheral blood of patients with inflammatory bowel disease. Peripheral blood lymphocytes, which were depleted of background natural killer (NK) activity (CD16-), from patients with Crohn's disease exhibited significantly enhanced levels of anti-CD3-triggered T-cell cytotoxicity compared with lymphocytes from normal subjects. Enhanced lytic activity was also found in some patients with ulcerative colitis and in patients with ulcerative colitis postcolectomy. These results were not influenced by treatment or disease activity. There was no correlation between the anti-CD3-triggered T lytic activity and the NK activity in normal subjects or in patients with inflammatory bowel disease. The surface antigen phenotype of the anti-CD3-triggered T killer cell was CD3+, CD8+, CD16-, and Leu 7+. The results provide indirect evidence for increased activity of a subpopulation of cytotoxic T cells, of unknown antigen specificity, in inflammatory bowel disease. Increased activity in patients with ulcerative colitis postcolectomy suggests that this might reflect a fundamental immunological disturbance.

T cell populations in the lacrimal gland during aging

The present study examined the influence of age and gender on T cell populations in the lacrimal gland. Lacrimal (exorbital) glands were obtained from male and female rats at 19 days (pre-puberty), 9 weeks (adult) and 14 months (mid-life) of age and tissues were processed for T cell subset identification. In females, the density of total (W3/13+ and OX 19+), helper/inducer (W3/25+) and suppressor/cytotoxic (OX 8+) T cells underwent a significant increase in tissues from before, to after puberty. Following this rise, the density of all T cell populations decreased in glands from young adult to midlife females. This pattern of accumulation contrasted with the T cell profile presented by glands from males: T cell densities appeared unaffected from 19 days to 9 weeks of age, and then either declined (OX 19+, W3/25) or remained unchanged (W3/13+, OX 8+) in tissues of 14 month rats. An influence of gender on the distribution of T cells was also apparent if results were corrected for age-associated variations in lacrimal gland weight. Thus, the absolute number of all T cell populations rose dramatically in glands of both sexes from pre- to post-puberty. However, from 9 weeks to 14 months of age, the total content of W3/13+, OX 19+, W3/25+ and OX 8+ lymphocytes decreased 2-fold in glands of females, but did not vary in tissues of males. Of interest, the number of W3/25+ and OX 8+ cells was analagous in all age groups examined. Moreover, the combined total of W3/25+ and OX 8+ cells was greater than that of W3/13+ or OX 19+ cells at every age.(ABSTRACT TRUNCATED AT 250 WORDS)

Contemporary issues: diseases with a food vector

Foodborne disease has become a contemporary issue. Several large, well-publicized outbreaks of foodborne disease have heightened public awareness that harmful microorganisms may be present in food and that chronic as well as acute disease may be caused by foodborne microbes. The field of food microbiology has likewise experienced a resurgence of interest. New tools, such as recombinant deoxyribonucleic acid technology and monoclonal antibody production, used to elucidate microbial virulence factors have facilitated identification of disease-causing microbes once thought to be harmless and demonstrated the complexity of individual virulence mechanisms previously considered to be well understood. Foodborne pathogens are also causing disease via some surprising food vectors, such as chopped, bottled garlic and sauteed onions. In addition to acute gastrointestinal disturbances, certain microorganisms may, through complex interactions with the human immune response, cause chronic diseases that affect several major organ systems. These microbes are serving as models in studies of molecular mimicry and genetic interrelatedness of procaryotes and eucaryotes. Other recently recognized attributes of foodborne microorganisms, such as the heat shock phenomenon and the possible nonculturability of some bacteria, may affect their ability to cause disease in humans. Because foodborne disease is a major cause of morbidity and mortality, the study of these diseases and their causative microorganisms presents a unique challenge to many professionals in the subdisciplines of microbiology, epidemiology, and clinical medicine.