Phagocytes in cell suspensions of human colon mucosa

Prevalence of Peripheral Eosinophilia at Diagnosis in Children With Inflammatory Bowel Disease

BACKGROUND AND OBJECTIVE

Inflammatory bowel disease (IBD) encompasses 2 disorders of unknown etiology: Crohn disease (CD) and ulcerative colitis (UC). There has been a continuous search for markers for disease activity. Eosinophils are granulocytic leukocytes that are implicated in the pathogenesis of IBD. The aim of this study was to examine the prevalence and significance of peripheral eosinophilia (PE) at diagnosis in children with IBD.

METHODS

A comprehensive chart review of all children with diagnosed as having IBD between January 2006 and August 2014 was performed. Patients with PE at diagnosis were compared with those without in relation to disease clinical activity and disease course.

RESULTS

A total of 109 children (mean age 14.6 ± 2.77, range 4.5-17.9 years, 55 boys) with IBD (68 with CD and 41 with UC) who were studied for a mean duration of 2.82 ± 1.89 (range 0.1-9.2 years) were identified. At diagnosis, 44 (40.4%) children had PE, which was more prevalent in patients with UC compared with those with CD (61.3% vs 36.3%, P < 0.05). At diagnosis, PE was more common in patients with high eosinophilic count in colonic biopsy samples (P < 0.01) and was significantly associated with disease activity as indicated by Pediatric CD Activity Index for children with CD (P < 0.05), Pediatric UC Activity Index for children with UC (P < 0.01).

CONCLUSIONS

PE is a common finding at diagnosis in children with IBD especially in those with UC. Patients with PE at diagnosis are more likely to present with higher clinical activity indices. PE is associated with more eosinophils in colonic biopsy samples.

Influences of the colonic microbiome on the mucous gel layer in ulcerative colitis

The colonic mucus gel layer (MGL) is a critical component of the innate immune system acting as a physical barrier to microbes, luminal insults, and toxins. Mucins are the major component of the MGL. Selected microbes have the potential to interact with, bind to, and metabolize mucins. The tolerance of the host to the presence of these microbes is critical to maintaining MGL homeostasis. In disease states such as ulcerative colitis (UC), both the mucosa associated microbes and the constituent MGL mucins have been shown to be altered. Evidence is accumulating that implicates the potential for mucin degrading bacteria to negatively impact the MGL and its stasis. These effects appear more pronounced in UC.   This review is focused on the host-microbiome interactions within the setting of the MGL. Special focus is given to the mucolytic potential of microbes and their interactions in the setting of the colitic colon.

Effects of proteoglycan on dextran sulfate sodium-induced experimental colitis in rats

Proteoglycans (PG) are macromolecules composed of glycosaminoglycan chains covalently attached to a protein core. In this study, we examined the effects of PG on dextran sulfate sodium (DSS)-induced experimental colitis in rats. First, to examine whether PG may ameliorate acute established DSS colitis, PG was administered orally for 5 days to the model animals. We evaluated the effects of PG on the basis of clinical symptoms, hematological analysis, macroscopic observation, and microscopic examination. We then examined whether PG administered orally to rats was detectable in their colonic lumen. After administration of PG, the colonic contents were collected, and the molecular weight of PG in the sample was analyzed by gel filtration high-performance liquid chromatography. Furthermore, we examined whether orally administered PG affected the concentrations of short-chain fatty acids (SCFAs) in the colonic feces. Orally administered PG ameliorated the clinical symptoms of bloody stools and diarrhea, and attenuated the increase in the white blood cell count in rats with established DSS colitis. Histologically, orally administered PG reduced the degree of mucosal erosion and inflammatory cell infiltration into the erosive area induced by DSS. Orally administered PG was detected in rat colon, although its molecular weight was slightly decreased. Orally administered PG significantly increased the concentration of total SCFAs and n-butyrate in rat colonic feces. This is the first study to indicate that exogenous PG ameliorates experimental colitis, suggesting the potential usefulness of PG for clinical treatment of colitis.

Enhanced clearance of Escherichia coli and Staphylococcus aureus in mice treated with cyclophosphamide and lactoferrin

Previous studies on cyclophosphamide (CP)-immunocompromised mice showed accelerated reconstitution of immune system function following oral treatment with lactoferrin (LF). The aim of this investigation was to evaluate the ability of mice, treated with a sublethal dose of CP and given LF, to combat bacterial infections. Mice were injected with a single, intraperitoneal dose of CP (350 mg/kg body weight). One group of CP-treated mice was also given LF in drinking water (0.5% solution) for 14 days. Untreated and LF-treated mice served as controls. On day 15 following CP administration, mice were infected intravenously with 10(8) Escherichia coli or 5 x 10(7) Staphylococcus aureus. Twenty-four hours later, the number of colony-forming units (CFU) in spleens and livers were determined. Phenotypic analysis of blood leukocytes was determined, as well as the ability of splenic and peritoneal cells to produce IL-6 spontaneously and in the presence of lipopolysaccharide (LPS). Treatment with CP, or with CP and LF, led to profound reduction of E. coli CFU in the liver and the spleen; treatment with LF alone had significant inhibitory effects on organ enumerated CFU. S. aureus CFUs were also significantly reduced in spleens of mice treated with CP or CP/LF and, to a lesser degree, after LF alone. These effects were also significantly reduced in the livers. Analysis of blood cellular phenotype revealed total number of peripheral leukocytes was lower in the CP-treated group (52.6%) but not significantly different from control values in CP/LF and LF-treated groups (90.7% and 104.6%, respectively). Conversely, percentage of blood neutrophils was markedly elevated in CP and CP/LF groups--62% and 42.5% vs. 18.4% in controls. These findings were accompanied by production of IL-6 by splenic and peritoneal cells which was significantly increased in CP- and CP/LF-treated groups. It was concluded that the increased clearance of bacteria in the organs of mice treated with CP and CP/LF may result from a rise in the number of neutrophils infiltrating the organs and contributing to accelerated clearance of bacteria. The study also suggests that the ability of cells from CP- and CP/LF-treated mice to produce significantly more IL-6 may also contribute to increased resistance to infections. Lastly, together with our previous data, this study indicates that LF used to reconstitute the antigen-specific immune response in CP-treated mice does not impair their resistance to infection.

Antimicrobial peptides in the first line defence of human colon mucosa

Antimicrobial peptides and proteins are effector molecules in the protection of epithelial surfaces. We have evaluated the presence of antimicrobial peptides/proteins that can participate in human colonic defence against microbes. A peptide/protein extract of normal human colon mucosa was found to be active against Gram-positive bacteria, Gram-negative bacteria, and fungi. Four polypeptides with antimicrobial activity were isolated from this material and they were identified by N-terminal amino acid sequence analysis as ubiquicidin, histone H2B, eosinophil cationic protein, and phospholipase A(2) (PLA(2)). Using immunodetection and mass spectrometry, LL-37, HNP1-3, and HBD-1 were also identified. Combined, these results indicate that the colon mucosa is protected by a complex mixture of polypeptides, able to kill invading microbes and working in synergy as a barrier against bacterial invasion.

Peripheral blood eosinophilia and eosinophil accumulation in coronary microvessels in acute Kawasaki disease

BACKGROUND

Early stage Kawasaki disease (KD) histopathology includes perivasculitis and vasculitis of the microvessels. The lesions then extend to larger vessels. Therefore the analysis of microvessel lesions is important to better understand the initial pathogenesis of KD vasculitis.

METHODS AND RESULTS

We studied epicardial microvessel lesions (<50 microm) and aneurysm lesions of paraffin-embedded cardiac tissues from 4 Japanese patients who died 7 to 22 days after KD onset. The cellular composition in the microvessel lesions was different from that in coronary aneurysm lesions; eosinophils were preferentially accumulated in the microvessel lesions. The average population of eosinophils was 16% of total infiltrated cells in the microvessel lesions, whereas it was 3% in the intima of aneurysm walls. We examined peripheral blood eosinophil cell counts in 95 KD patients and 95 febrile age-matched controls. Baseline eosinophil cell counts in KD patients were higher than those in febrile control patients (361 +/- 441 65 +/- 133; < 0.0001). Eosinophilia (>350 cells/microl) before therapy was documented in 36% of KD patients, but in only 4% of febrile controls ( < 0.0001). Sixty-six KD patients (69%) developed eosinophilia within 2 weeks of illness.

CONCLUSIONS

Because the numbers of circulating eosinophils in the body are tightly regulated, eosinophil accumulation in blood or tissues may reflect the host's immune response against KD related antigen(s).

Microbes involved in dissimilatory nitrate reduction in the human large intestine

Nitrate-limited batch cultures, incorporating 20 different fermentation substrates and inoculated with human faeces, mainly selected for the growth of enterobacteria. The microbial diversity involved was determined by a combination of phenotypic and genotypic procedures. Continuous culture with lactate as the sole electron donor selected for similar micro-organisms, but when antibiotics were incorporated to inhibit Escherichia coli and lactate was replaced with choline, there was a wider microbial diversity recovered. Clostridium ramosum and Bacteroides vulgatus were then isolated as well as enterobacteriaceae.

Advances in the immunobiology of eosinophils and their role in disease

Eosinophils play a protective role in host immunity to infections by parasitic worms and, detrimentally, are involved in the pathophysiology of asthma and other allergic diseases. Airway inflammation is central to the pathology of asthma and is characterized by infiltration of the bronchial mucosa by large numbers of proinflammatory cells, amongst which the eosinophil is prominent despite being a minority constituent of circulating leukocytes. Crucial steps in eosinophilic inflammation include augmented production of eosinophils in the bone marrow, their increased release into the circulation, and their selective accumulation in the conducting airways. The eosinophil has a potent armory of proinflammatory mediators, including cytotoxic granule proteins, cytokines and lipid mediators with considerable potential to initiate and sustain an inflammatory response. Thus there is much interest in the elucidation of the mechanisms responsible for eosinophil accumulation, persistence, activation and ultimate fate. This article reviews our current understanding of the role of the eosinophil in human disease and the immunobiology of this important proinflammatory cell.

Differential lamina propria cell migration via basement membrane pores of inflammatory bowel disease mucosa

BACKGROUND & AIMS

In active inflammatory bowel disease (IBD), the intestinal mucosa is infiltrated by polymorphonuclear cells (PMNs), lymphocytes, and monocytes from the systemic circulation. Using an ex vivo model, we have investigated luminally directed migration of cells out of the lamina propria.

METHODS

Fresh untreated and deepithelialized mucosal samples were studied by electron microscopy. Cells migrating out of the lamina propria were investigated by immunohistochemistry and fluorescence-activated cell sorter analysis.

RESULTS

In intact IBD mucosal samples, tunnels containing cells were prominent in the lamina propria matrix, and PMNs, but not other cell types, were prominent in the epithelium. In deepithelialized mucosal samples, the basement membrane was either destroyed or contained numerous large pores. During culture of deepithelialized mucosal samples, many cells (3.3 [+/-0.8] x 10(5) . g tissue-1 . h-1) migrated out of the lamina propria via basement membrane pores. PMNs and eosinophils were prominent during the first 3 hours of culture, but T cells predominated thereafter. Macrophages also migrated, but B cells were the minority population (<2%) at all times.

CONCLUSIONS

In active IBD mucosa with an intact epithelium, luminally directed migration of lamina propria cells is restricted mainly to PMNs. After loss of the epithelium, other cell types also migrate into the lumen via numerous, large, basement membrane pores.

Eosinophil activation in ulcerative colitis: studies on mucosal release and localization of eosinophil granule constituents

Activation of eosinophil granulocytes (eosinophils) seems to contribute to the pathophysiology of several inflammatory conditions. This process was evaluated in 18 patients with ulcerative colitis and in 18 healthy controls using intraluminal segmental perfusion of the sigmoid colon and rectum and immunoanalysis for eosinophil cationic protein (ECP) in the perfusate. Immunohistochemistry for eosinophils and neutrophils was made in simultaneously taken biopsies and in biopsies from surgical specimens taken from additional 10 patients. The mucosal release of ECP was increased severalfold in patients with UC. The bowel biopsies demonstrated a lamina propria infiltrated with eosinophils. The degree of eosinophil activation/degranulation was related to the intensity of the inflammatory reaction. Activated eosinophils and extracellular deposits of ECP were, in particular, seen in crypt abscesses and in areas with damaged surface epithelium. Since ECP is highly cytotoxic, its release at the site of inflammatory bowel lesions might reflect a potential pathophysiological mechanism.

Isolation and purification of CD14-negative mucosal macrophages from normal human small intestine

Mucosal macrophages play a fundamental role in the regulation of immunological events and inflammation in the small intestine. Because no information is available on normal small intestinal macrophages, we developed a technique for the isolation and purification of jejunal lamina propria macrophages in order to study their phenotype and activity. From sections of normal human jejunum, lamina propria mononuclear cells were isolated by neutral protease digestion and then subjected to counterflow centrifugal elutriation to purify the macrophages. The cells isolated by this procedure contained < 1% CD3+ lymphocytes and displayed the size distribution, morphological features, ultrastructure and phagocytic activity of mononuclear phagocytes. In contrast to blood monocytes, however, mucosal macrophages from the jejunum did not exhibit adherence properties or express CD14, a receptor for the lipopolysaccharide-binding protein. The purification of large numbers of lamina propria macrophages by this procedure offers the opportunity to define the role of this cell in the physiological inflammation characteristic of normal intestinal mucosa and the pathological inflammation associated with small intestinal diseases.

Antigen presentation in the intestine

The intestinal mucosa is the largest surface area in the body which is continually exposed to an enormous amount of food antigens, viruses, bacteria, parasites or the by-products of these organisms. In such an antigen-loaded environment, specialized defence mechanisms must exist. There is clear evidence that the function of lymphocytes in the intestinal mucosa (IELs or LPLs) is different from that of lymphocytes of the peripheral blood, lymph node or spleen (these are antigen-free organs). The basic processes of these reactions are not completely understood. The role of differential antigen handling and presentation, and the non-random distribution of responsibilities between the professional and non-professional APC in this regard, have not been characterized. Thus, much remains to be learned about the basic mechanisms of antigen uptake, processing and presentation in the intestine which are necessary to induce an immune response. Diversity in APC function is a natural requirement for the maintenance of homeostasis in the intestine. Subpopulations of professional and non-professional APC may have been programmed to function in such a way that non-professional APCs may play a dominant role. It is anticipated that in vivo model systems will be developed and that eventually a clearer understanding will be gained in this rapidly evolving field.

Tissue distribution and cytofluorometric analysis of oral mucosal T cells in the BALB/c mouse

The incidence and distribution of Thy-1.2+, Lyt-2.2+ and L3T4+ cells in the murine oral mucosa were investigated using qualitative and quantitative approaches. From immunostaining of frozen tissue sections, it appeared that the majority of oral T cells are located either in the epithelium or within the minor salivary gland network. The occurrence of Thy-1.2+, L3T4+ and Lyt-2.2+ cells at these sites points to two strategic lines of defence in the event of mucosal infections or aggression. A quantitative analysis of oral T-cell subsets was made possible by optimizing an enzymatic digestion procedure which preserves all three T-cell surface markers. Flow cytometric analysis of oral mucosal cells demonstrated that the helper phenotype is about twice as numerous as the cytotoxic/suppressor phenotype in the mucosa. Furthermore, in single cell suspensions, virtually all Thy-1+ cells were either L3T4+ or Lyt-2.2+ in the mucosa and in the spleen. From this frequency analysis and our previous studies, we conclude that T cells are a major component of the oral immune system, being 2-3 times as numerous as B cells or macrophages. Present data on the spatial distribution and characteristic ratio of T-cell subsets assess the basal activity of the local T-cell populations in healthy animals and lay the basis for comparative studies of both qualitative and quantitative variations occurring during mucosal infections or autoimmune reactions.

Hydrogen peroxide stimulates rat colonic prostaglandin production and alters electrolyte transport

The changes in short circuit current (electrogenic Cl- secretion) of rat colon brought about by xanthine/xanthine oxidase in the Ussing chamber were inhibited by catalase and diethyldithiocarbamate, but not by superoxide dismutase. These results, the reproduction of the response with glucose/glucose oxidase and with exogenous H2O2, and the lack of effect of preincubation with deferoxamine or thiourea implicate H2O2, and not O2- or OH., as the important reactive oxygen metabolite altering intestinal electrolyte transport. 1 mM H2O2 stimulated colonic PGE2 and PGI2 production 8- and 15-fold, respectively, inhibited neutral NaCl absorption, and stimulated biphasic electrogenic Cl secretion with little effect on enterocyte lactic dehydrogenase release, epithelial conductance, or histology. Cl- secretion was reduced by cyclooxygenase inhibition. Also, the Cl- secretion, but not the increase in prostaglandin production, was reduced by enteric nervous system blockade with tetrodotoxin, hexamethonium, or atropine. Thus, H2O2 appears to alter electrolyte transport by releasing prostaglandins that activate the enteric nervous system. The change in short circuit current in response to Iloprost, but not PGE2, was blocked by tetrodotoxin. Therefore, PGI2 may be the mediator of the H2O2 response. H2O2 produced in nontoxic concentrations in the inflamed gut could have significant physiologic effects on intestinal water and electrolyte transport.

Neutrophil and eosinophil involvement of the small bowel in patients with celiac disease and Crohn's disease: studies on the secretion rate and immunohistochemical localization of granulocyte granule constituents

PURPOSE

The concentrations of myeloperoxidase (MPO), a neutrophil granule constituent, and eosinophil cationic protein (ECP), a specific eosinophil granule protein, were measured in jejunal perfusion fluid in an attempt to elucidate the neutrophil and eosinophil involvement of the small bowel in health and disease.

PATIENTS AND METHODS

The control group consisted of 14 males and two females. Ten patients (seven males and three females) with Crohn's disease and seven patients (two males and five females) with celiac disease were also studied; in addition, one patient with relapsing giardiasis, one patient with giardiasis and complete absence of plasma cells in small intestinal lamina propria, and one patient with selective IgA deficiency and no IgA plasma cells in duodeno-jejunal lamina propria were evaluated. Segmental perfusion of the jejunum was performed according to a previously described method. MPO and ECP were measured by radioimmunoassays.

RESULTS

In healthy control subjects, the concentrations of both granule proteins were in a narrow range and much higher than would have been anticipated from passive leakage from circulating blood. In patients with celiac disease, the perfusion fluid concentrations of MPO and ECP were on average 3.5 and eight times, respectively, higher than the values seen in the controls. The jejunal segment perfused in patients with Crohn's disease was endoscopically and histologically normal. The perfusion fluid concentrations of MPO and ECP were increased 3.5 and two times, respectively, compared with that in the control subjects. Both patient groups and the control group had similar perfusion fluid concentrations of albumin. Data on MPO and ECP expressed as jejunal secretion rates gave the same differences between patients and controls as just described for the jejunal fluid concentrations. Immunohistochemical studies of jejunal biopsy specimens from another group of patients with celiac disease demonstrated a prominent extracellular deposit of ECP in the lamina propria of the atrophic intestinal mucosa, whereas the release of neutrophil constituents (cathepsin G, MPO) was scarce. In Crohn's disease, an extracellular degranulation of ECP and, to a lesser extent, of cathepsin G was observed in relation to ulcerations only.

CONCLUSION

Data obtained indicate that the local release of neutrophil and eosinophil granule components is enhanced in the jejunal tissue from patients with celiac sprue and Crohn's disease. The prominent extracellular deposit of eosinophil granule constituents with cytotoxic properties at the site of inflammatory intestinal lesions in celiac sprue might reflect a pathophysiologic mechanism.(ABSTRACT TRUNCATED AT 400 WORDS)