Resistance of normal serum IgA and secretory IgA to bacterial IgA proteases: evidence for the presence of enzyme-neutralizing antibodies in both serum and secretory IgA, and also in serum IgG

Normal serum IgA and secretory IgA (sIgA) of subclass IgA1 were isolated from pooled human serum and milk, respectively. They were tested for their susceptibility to bacterial IgA proteases from Haemophilus influenzae, Streptococcus pneumoniae, Neisseria gonorrhoeae, and Neisseria meningitidis that cleave IgA of only the IgA1 subclass. They were also tested for susceptibility to a novel IgA-protease from Clostridium ramosum that cleaves IgA of the IgA1 as well as the IgA2 subclass of the A2m(1) allotype. Both normal serum IgA1 and sIgA1 exhibited resistance to most IgA proteases. The one exception was the IgA protease from C. ramosum which readily cleaved both the serum IgA1 and sIgA1 into Fab and Fc fragments. Secretory component (SC) had nothing to do with the resistance of these IgAs. The resistance of these IgAs to most of the IgA proteases was found to be due to their enzyme-neutralizing antibody activity, since the Fab but not the Fc fragment of sIgA1 showed enzyme-inhibitory activity against these IgA proteases. Similar enzyme-neutralizing antibody activity was found in the pepsin-digested normal serum IgG-(Fab')2 fragment. These results indicate that the induction of the enzyme-neutralizing antibodies against the bacterial IgA proteases took place not only in mucosal sIgA but also in serum IgA and IgG. No enzyme-neutralizing antibody activity against the novel IgA-protease of C. ramosum was detected in any immunoglobulin preparations used in the present study or in the serum of a patient who carries the IgA protease-producing strain of C. ramosum in his feces.     

Molecular analysis of microbial communities in mobile deltaic muds of Southeastern Papua New Guinea

A PCR-based approach combined with microbiological cultivation methods was employed to determine the occurrence of sulfate-reducing bacteria (SRB) in colon biopsy samples from ulcerative colitis patients and from non-colitic controls. The detection of mucosa-associated SRB was carried out by digoxigenin-dUTP-labelled PCR amplification, in liquid Postgate medium B and in a new liquid medium, termed VM medium I. Using Postgate medium B, the growth of SRB was confirmed in 92% of the colitic specimens and in 52% of non-colitic samples. However, PCR analysis and incubation in VM medium I detected SRB in 100% of biopsy material indicating ubiquitous presence of SRB in human colon mucosa.     

Serpin B1 protects colonic epithelial cell via blockage of neutrophil elastase activity and its expression is enhanced in patients with ulcerative colitis

Serpin B1 is a monocyte neutrophil elastase (NE) inhibitor and is one of the most efficient inhibitors of NE. In the present study, we investigated the role of serpin B1 in the pathogenesis of ulcerative colitis by using clinical samples and an experimental model. The colonic expression of serpin B1 was determined by real-time polymerase chain reaction (PCR), Western blot analysis, and immunohistological studies in both normal and inflamed mucosa from patients with ulcerative colitis. Serpin B1 mRNA expression was determined by real-time PCR in the mouse dextran sodium sulfate (DSS)-induced colitis model. Young adult mouse colonic epithelial (YAMC) cells were used to determine the role of serpin B1. Serpin B1 gene transfected YAMC cells were treated with H(2)O(2) to measure cell viability. The expression of NE was determined in YAMC cells treated with H(2)O(2). NE-silenced YAMC cells were also treated with H(2)O(2) and then measured for viability. Upregulated expression of serpin B1 in colonic mucosa was confirmed from patients with active ulcerative colitis. Immunohistochemical studies showed that serpin B1 expression was localized not only in inflammatory infiltration cells but also in epithelial cells. Serpin B1 mRNA expression was also increased in colonic mucosa of mouse DSS-induced colitis. Serpin B1-transfected YAMC cells were resistant against the treatment of H(2)O(2). H(2)O(2) treatment significantly induced NE in YAMC cells, and NE-silenced YAMC cells were also resistant against the treatment of H(2)O(2). These results suggest that serpin B1 may be a novel marker of active ulcerative colitis and may play an important role in the pathogenesis of inflammatory bowel disease.     

The Clostridium ramosum IgA proteinase represents a novel type of metalloendopeptidase

Clostridium ramosum is part of the normal flora in the human intestine. Some strains produce an IgA proteinase that specifically cleaves human IgA1 and the IgA2m(1) allotype. This prolylendopeptidase was purified from a broth culture supernatant, and N-terminal sequences of the native protein and tryptic fragments thereof were determined. A fragment of the iga gene encoding the IgA proteinase was isolated using degenerate primers in PCR, and the complete gene was obtained by inverse PCR. The identity of the iga gene was confirmed by heterologous expression in Escherichia coli. The deduced amino acid sequence indicated a signal peptide of 30 residues and a secreted proteinase of 133,828 Da. A typical Gram-positive cell wall anchor motif was identified in the C terminus. The presence of a putative zinc-binding motif His-Glu-Phe-Gly-His together with inhibition studies indicate that the proteinase belongs to the zinc-dependent metalloproteinases. However, the sequence of the C. ramosum IgA proteinase shows no overall similarity to other proteins except for significant identity around the zinc-binding motif with family M6 of metalloendopeptidases, and the unique sequence of the IgA proteinase in this area presumably establishes a new subfamily. The GC percentage of the iga gene is significantly higher than that for the entire genome of C. ramosum, suggesting that the gene was acquired recently in evolution.     

Gastrointestinal tract microflora in nonspecific ulcerative colitis]

The species and quantitative composition of the normal and conditionally pathogenic microflora of the stomach, the proximal portion of the small intestine, in material obtained by biopsy from the mucosa of this portion, and in feces was studied in 10 patients with non-specific ulcerative colitis. The study was made before and after treatment. Before treatment in most of the patients gastric juice and the proximal portion of the small intestine were found to be greatly contaminated with microflora commonly present in feces, and in fecal microflora sharp dysbiotic changes were observed. As a result of treatment the microflora was essentially normalized (with the exception of Proteus and bifidobacteria).     

Adhesive Escherichia coli in inflammatory bowel disease and infective diarrhoea.

The clinical features of ulcerative colitis and Crohn''s disease are similar to those of infections of the bowel, although their cause is uncertain. Many bacteria that cause intestinal diseases adhere to the gut mucosa, and adhesion of pathogenic Escherichia coli is resistant to D-mannose. The adhesive properties of isolates of E coli were assessed by assay of adhesion to buccal epithelial cells with mannose added. The isolates were obtained from patients with inflammatory bowel diseases (50 with a relapse of ulcerative colitis, nine with ulcerative colitis in remission, 13 with Crohn''s disease, and 11 with infectious diarrhoea not due to E coli) and 22 controls. The median index of adhesion to buccal epithelial cells (the proportion of cells with more than 50 adherent bacteria) for E coli from patients with ulcerative colitis in relapse was significantly higher (43%) than that for controls (5%) and patients with infectious diarrhoea (14%). The index was not significantly different among isolates from patients with ulcerative colitis in relapse, Crohn''s disease (53%), and ulcerative colitis in remission (30%). If an index of adhesion of greater than 25% is taken as indicating an adhesive strain 86% of isolates of E coli from patients with inflammatory bowel disease were adhesive compared with 27% from patients with infective diarrhoea and none from controls. The adhesive properties of the isolates from patients with inflammatory bowel disease were similar to those of pathogenic intestinal E coli, raising the possibility that they may have a role in the pathogenesis of the condition; the smaller proportion of adhesive isolates in patients with infective diarrhoea due to other bacteria suggests that the organism may be of primary importance rather than arising secondarily.     

Secretory leukocyte protease inhibitor in punch biopsies from human colonic mucosa.

Secretory leukocyte protease inhibitor (SLPI) is a well-known protease inhibitor. Its function is thought to be protease/protease-inhibitor balance. Free proteolytic activity, mainly pancreatic elastase, anionic trypsin and granulocytic elastase, has been demonstrated in faecal extracts from patients with ulcerative colitis. We wanted to verify that SLPI is actually secreted from normal human colonic mucosa. Also, we wanted to ascertain whether studies of SLPI secretion based on punch biopsies were dependent on biopsy area or on biopsy circumference. Normal colonic mucosa was sampled during surgery for colonic cancer. A total of 36 samples from four patients were used. Mucosa preparation was carried out using a punch biopsy technique, and samples of 3, 4 and 6 mm diameter were used. All media contained SLPI at varying concentrations. When expressed in terms of the sample area, the secretion per millimetre-squared seemed to decrease with increasing area. When calculated as secretion per circumference, secretion seemed to be constant. In conclusion, SLPI was secreted from normal human colonic mucosa. The SLPI secretion seemed dependent on the circumference of the biopsy rather than on the area of the biopsy.     

Comparison of different techniques for detection of Gal-GalNAc, an early marker of colonic neoplasia

The tumor marker, D-galactose-beta [1-3]-N-acetyl-D-galactosamine (Gal-GalNAc, also known as T-antigen) can be identified by a very simple galactose oxidase-Schiff's (GOS) reaction either on tissues or on rectal mucus samples from patients with colorectal neoplasms. Gal-GalNAc is expressed in the neoplastic mucosa as well as the remote non-neoplastic mucosa. It is, however, not expressed in colonic mucosa of normal subjects. We studied the expression of Gal-GalNAc by GOS reaction, lectin reactivity and immunocytochemistry in 10 normal, .45 precancerous [5 Crohn's disease, 15 ulcerative colitis (5 without dysplasia and 10 with dysplasia), 25 tubular adenomas], and 25 adenocarcinoma cases. Normal mucosa remote from tubular adenoma and adenocarcinoma was also studied. The GOS method was compared with reactivity of the lectin jacalin and immunostaining with antibody to T antigen (Anti-Tag Ab). GOS reaction was negative in all of the 10 normal specimens. Of the 5 Crohn's disease specimens, 2 were positive and 3 negative. In the 5 ulcerative colitis cases without dysplasia, positive reaction was seen in 2 cases and negative in 3. Of the 10 cases of ulcerative colitis with dysplasia, 5 showed positivity in dysplastic areas, and 3 of these were also positive in remote non dysplastic mucosa. Twenty of 25 tubular adenomas yielded a positive reaction in the adenoma, 14 of them showing positivity also in remote mucosa; 3 cases showed a positive reaction only in remote mucosa. Of the 25 adenocarcinomas, 21 showed a positive reaction in the adenocarcinoma as well as the remote mucosa. GOS reaction was intense in well differentiated adenocarcinoma and weak in poorly differentiated adenocarcinoma. Intense reaction was also seen in the intracellular mucus of some aberrant crypts and morphologically normal crypts remote from adenocarcinoma and tubular adenoma. GOS reaction showed an overall sensitivity of 75.7% and specificity of 100% for cancer and precancerous lesions. Jacalin reactivity was slightly more sensitive (84.3%) but less specific (80%) and Tag Ab reactivity even less sensitive (50%) but as specific (100%) for neoplastic and dysplastic mucosa. We conclude that the detection of the carbohydrate moiety Gal-GalNAc varies with the technique used. Compared to other techniques, GOS reaction is extremely simple and has a high degree of sensitivity and specificity. It can be used for detection of this tumor marker in remote non-neoplastic mucosa of patients with neoplasia or at risk of developing neoplasia. It, therefore, could be used as a cost effective screening test in rectal biopsy specimens of such patients.     

Oxygen radicals in ulcerative colitis.

This article reviews the pathophysiologic concept that superoxide and hydrogen peroxide, generated by activated leukocytes, together with low-molecular-weight chelate iron derived from fecal sources and from denatured hemoglobin, amplify the inflammatory response and subsequent mucosal damage in patients with active episodes of ulcerative colitis. The putative pathogenic mechanisms reviewed are as follows: (1) Dietary iron is concentrated in fecal material owing to normally limited iron absorption. (2) Mucosal bleeding, characteristic of ulcerative colitis, as well as supplemental oral iron therapy for chronic anemia, further conspire to maintain or elevate mucosal iron concentration in colitis. (3) Fenton chemistry, driven especially by leukocyte-generated superoxide and hydrogen peroxide, leads to formation of hydroxyl radicals. (4) The resultant oxidative stress leads to the extension and propagation of crypt abscesses, either through direct membrane disruption by lipid peroxidation or through generation of secondary toxic oxidants such as chloramines. (5) Chemotactic products of lipid peroxidation, including 4-hydroxynonenal, provide positive feedback to accelerate this inflammatory/oxidative process, leading to acute exacerbations of the disease. (6) Other oxidized products, such as oxidized tryptophan metabolites, created by free radical mechanisms in or near the mucosa, may act as carcinogens or tumor promotors that contribute to the exceedingly high incidence of colon carcinoma in patients suffering from chronic ulcerative colitis. In this way, self-sustaining cycles of oxidant formation may amplify flare-ups of inflammation and mucosal injury in ulcerative colitis. This concept, if proved correct by subsequent research, would provide a rationale for several novel clinical approaches to the management of ulcerative colitis, including use of SOD mimetics, iron chelators, and chain-breaking antioxidants.     

Isolation and characteristics of IgA1 and its use for detecting bacterial IgA1 proteases

Sufficiently purified IgA, subclass I, has been isolated from the defibrinated plasma of a myeloma patient by chromatography on columns packed with DEAE-Sephadex A-50 or Sephadex G-200, and rabbit antiserum to this immunoglobulin has been obtained. These preparations have been used for detecting specific protease in Bordetella pertussis. The tested B. pertussis strains have been shown to induce, as revealed by immunoelectrophoretic methods, the proteolysis of human IgA, subclass I.     

Clostridium difficile in emergency room

Clostridium difficile strains are known as etiological agents of pseudomembranous colitis (PMC), antibiotic-associated diarrhea (AAC) and colitis (AAC) and hospital-acquired infections. The aim of this study was to determine the frequency of C. difficile infection among patients in the emergency room and to compare isolated strains by phenotypic and genotypic characteristics. During a period of 11 months, 56 stool samples taken from diarrheic patients hospitalized in the emergency room of the Medical Center UC Davis and 14 environmental samples were cultured for isolation of C. difficile strains. Eighteen C. difficile strains were isolated from stool samples cultured on selective TCCCA plates and 5 strains from environmental samples using Rodac plates. Eleven toxigenic (TcdA+/TcdB+), 6 non-toxigenic (TcdA-/TcdB-) and unique toxin A-negative/toxin B-positive (TcdA-/TcdB+) C. difficile strains were detected among patients' isolates and 3 toxigenic and 2 non-toxigenic strains-among environmental samples. The majority of C. difficile-positive patients were treated previously by antibiotics. Four strains isolated from patients' fecal samples and one strain isolated from the environment demonstrated high-level resistance to erythromycin and clindamycin (MIC >256mug/mL). The results obtained by AP-PCR and PCR-ribotyping revealed genetic heterogeneity among the strains isolated from patients' fecal samples. However, similarity was observed among environmental strains and strains isolated from patients' fecal samples. Considering the importance of emergency room patients as a potential source of C. difficile strains, it appears to be important examine these patients for C. difficile before transfer to the other hospital units.     

Raised titres of anti-klebsiella IgA in ankylosing spondylitis,rheumatoid arthritis,and inflammatory bowel disease

Serum titres of IgA are raised in ankylosing spondylitis and increased titres of antibodies to klebsiella have also been reported. The humoral response was investigated in ankylosing spondylitis and other inflammatory disorders. IgA antibodies to klebsiella pneumoniae K43 were measured in patients with ankylosing spondylitis, Crohn''s disease, ulcerative colitis, and rheumatoid arthritis and in controls. Significantly raised median titres of anti-klebsiella IgA, measured as optical density at 405 nm with an enzyme linked immunosorbent assay (ELISA), were seen among the patients with ankylosing spondylitis (0·7), Crohn''s disease (0·8), rheumatoid arthritis (0·6), and ulcerative colitis (0·8) compared with controls (0·4). Activity of disease in ankylosing spondylitis and titres of anti-klebsiella IgA were not correlated. In contrast, titres of anti-klebsiella IgM were significantly lower in patients with ankylosing spondylitis and ulcerative colitis.The increase in the titres of anti-klebsiella IgA may be due to increased permeability of the gut to bacterial antigens, leading to an increased IgA response in the gut mucosa and permitting the release of IgA into the circulation. As the increased antibody titres were seen in Crohn''s disease and rheumatoid arthritis as well as in ankylosing spondylitis the response may be non-specific, occurring because of possible underlying inflammatory bowel disease in these conditions.     

Subclass of individual IgA-secreting human lymphocytes. Investigation of in vivo pneumococcal polysaccharide-induced and in vitro mitogen-induced blood B cells by monolayer plaque-forming cell assays

The subclass of individual human IgA B cells was investigated by means of monolayer plaque-forming cell assays permitting analysis of all IgA-secreting cells as well as of cells secreting IgA anti-pneumococcal polysaccharide antibody. Center cells were examined by indirect immunofluorescence staining with mouse mAb against either of the two IgA subclasses as primary antibodies and FITC-conjugated rabbit anti-mouse Ig as the second antibody. Blood lymphocytes spontaneously secreting IgA (mean 399/10(6) mononuclear cells) produced mainly IgA1 (73%). A similar distribution of subclasses was recorded among IgA-secreting blood cells in PWM- and EBV-stimulated cultures. In contrast, a predominance of IgA2 (54%) was found among IgA-secreting cells (2531/10(6)) isolated from the blood 7 days after in vivo stimulation with pneumococcal polysaccharides, and a similar proportion (51%) of IgA2 producing cells was found among IgA anti-pneumococcal polysaccharide-secreting cells. It was thus confirmed that IgA1 is the predominant subclass of blood IgA-secreting cells in general. However, the high percentage of IgA2-secreting cells found after vaccination with pneumococcal polysaccharides suggests that these Ag have an unusually high ability to activate IgA2 B cells, or that the B cells stimulated originate from lymphatic tissues with a high frequency of IgA2 committed cells.     

Comparison of intestinal microflora in healthy infants and infants with allergic colitis

Twenty-eight exclusively breast-fed healthy infants and 16 infants also exclusively breast-fed with allergic colitis (aged 85 +/- 60 and 98 +/- 58 d, respectively) were screened for differences in fecal flora. Bifidobacteria were detected in 23 healthy infants and only in 4 fecal samples of infants with allergic colitis. All bifidobacteria-free infants possessed Gram-positive regular rods as a major group of their fecal flora. These bacteria were identified as clostridia using genus-specific FISH probe. Infants with allergy colitis possessed significantly lower counts of bifidobacteria and total anaerobes and significantly higher counts of clostridia in their feces. In healthy infants, Bifidobacterium longum was the most frequently found species (54.5% of the samples), followed by B. adolescentis (20.0), B. breve (18.2), B. bifidum (16.4), B. dentium (10.9) and B. pseudocatenulatum (1.80). Bifidobacterial isolates from two babies with allergic colitis were identified as B. longum, one child from patients group contained species B. dentium and one baby B. adolescentis. Our results suggest that there are significantly lower counts of bifidobacteria in infants with allergic colitis than in healthy infants.     

Cytotoxicity and antimicrobial susceptibility of Clostridium difficile isolated from hospitalized children with acute diarrhea

Clostridium difficile is an important pathogen associated with outbreaks of pseudomembranous colitis and other intestinal disorders such as diarrhea. In this study, 181 stool samples from children with and without acute diarrhea were analysed. Eighteen children with acute diarrhea were positive to C. ramosum, C. difficile, C. limosum, C. clostridioforme, C. septicum, C. butyricum, C. innocuum and Clostridium sp. Nineteen children without diarrhea harbored C. ramosum, C. septicum, C. barattii, C. butyricum, C. innocuum, C. sphenoides, C. bifermentans, C. clostridioforme and C. paraputrificum. No patient with diarrhea harbored C. barattii, C. bifermentans, C. paraputrificum and C. sphenoides. In addition, ten C. difficile strains were detected in 5 (5.5%) of the children with diarrhea. Also, no children from control group harbored C. difficile, C. limosum and Clostridium sp. Most of the tested strains were resistant to all the used antimicrobial. Nine C. difficile were toxigenic on VERO cells and by multiplex PCR, six strains showed both toxin A and B genes and three strains showed only toxin B gene. In this study, the presence of C. difficile was not significant, and it is suggested the need of more studies to evaluate the role of clostridia or C. difficile play in the childhood diarrhea and these organisms must be looked for routinely and a periodic evaluation of antimicrobial susceptibility should be performed.     

Upregulation of CFTR expression but not SLC26A3 and SLC9A3 in ulcerative colitis

In inflamed colonic mucosa, the equilibrium between absorptive and secretory functions for electrolyte and salt transport is disturbed. We compared the expression of three major mediators of the intestinal salt transport between healthy and inflamed colonic mucosa to understand the pathophysiology of diarrhea in inflammatory bowel disease. Expression levels of the cystic fibrosis transmembrane regulator (CFTR) (Cl- channel), SLC26A3 (Cl-/HCO exchanger) and SLC9A3 (Na+/H+ exchanger) mRNAs were measured by real-time quantitative RT-PCR in peroperative colonic samples from controls (n = 4) and patients with ulcerative colitis (n = 10). Several samples were obtained from each individual. Tissue samples were divided into three subgroups according to their histological degree of inflammation. Expression of CFTR and SLC26A3 proteins were determined by immunohistochemistry and Western blotting from the same samples, respectively. Increased expression of CFTR mRNA was observed in all three groups of affected tissue samples, most pronounced in mildly inflamed colonic mucosa (5-fold increase in expression; P < 0.001). The expression of the CFTR protein was detected from health and inflamed colon tissue. Although the expression of the SLC26A3 mRNA was significantly decreased in severe ulcerative colitis (P < 0.05), the SLC26A3 protein levels remained unchanged in all groups. The expression of SLC9A3 mRNA was significantly changed between the mild and severe groups. Intestinal inflammation modulates the expression of three major mediators of intestinal salt transport and may contribute to diarrhea in ulcerative colitis both by increasing transepithelial Cl- secretion and by inhibiting the epithelial NaCl absorption.     

Detection ofCandida albicans by culture, serology and PCR in clinical specimens from patients with ulcerative colitis: Re-evaluation of an old hypothesis with a new perspective

The relationship between inflammatory bowel disease and microorganisms was evaluated. The presence of Candida albicans-specific IgM and IgG antibodies in serum samples and the presence of C. albicans in stool and colonal mucosa samples of the patients did not exhibit any significant difference between 21 patients in active stage and 15 patients in remission of ulcerative colitis (UC) (compared with 19 control patients). The invasion of yeast cells to the colonal mucosa was demonstrated by detecting C. albicans DNA using specific PCon1, PCon2, and PspA2 primers in PCR assay. Eighteen of 36 patients (50%) were found to be DNA positive while in 19 controls only 4 (21%) were found to be positive. The presence of DNA in the association of the positive serological reactivity is suggested as an important diagnostic marker of UC.     

Treatment and mechanism of fecal microbiota transplantation in mice with experimentally induced ulcerative colitis

Restoring intestinal microbiota dysbiosis with fecal microbiota transplantation is considered as a promising treatment for ulcerative colitis. However, the mechanisms underlying its relieving effects remain unclear. Ulcerative colitis pathogenesis is associated with the involvement of immune cells and inflammatory cytokines. Here, we aimed to investigate the effect of fecal microbiota transplantation on T cell cytokines in a dextran sulfate sodium-induced ulcerative colitis mouse model. Five-aminosalicylic acid (5-ASA) was used as the positive control. Male C57BL/6 mice were randomly assigned to control, model (UC), UC + FMT, and UC + 5-ASA groups. Each group consisted of five mice. The establishment of the mouse model was verified by fecal occult-blood screening and hematoxylin–eosin staining. Results showed that fecal microbiota transplantation reduced colonic inflammation, significantly decreased T helper (Th)1 and Th17 cells, interferon-gamma, interleukin-2 and interleukin-17, as well as significantly increased Th2 and regulatory T (Treg) cells, interleukin-4, interleukin-10, and transforming growth factor-beta, and improved routine blood count. Furthermore, 16S rRNA gene-sequencing analysis showed a significant increase in the relative abundance of genus Akkermansia and a significant decrease in the relative abundance of genus Helicobacter in the ulcerative colitis group. Fecal microbiota transplantation restored the profile of the intestinal microbiota to that of the control group. These findings demonstrated the capability of fecal microbiota transplantation in controlling experimentally induced ulcerative colitis by improving Th1/Th2 and Th17/Treg imbalance through the regulation of intestinal microbiota.     

Campylobacter colitis.

Eleven consecutive patients with diarrhoea from whose stools campylobacter were isolated were investigated by sigmoidoscopy and rectal biopsy. Eight had definite proctitis, and in seven biopsy specimens were abnormal with histological changes ranging from non-specific colitis to gross colitis with goblet-cell depletion and crypt-abscess formation. Nine of the patients passed blood in their stools, and in all but one abdominal pain was a feature of the illness. Severe campylobacter colitis may be clinically, sigmoidoscopically, and histologically difficult to differentiate from ulcerative colitis and is a differential diagnosis in acute colitis.     

A novel IgA protease from Clostridium sp. capable of cleaving IgA1 and IgA2 A2m(1) but not IgA2 A2m(2) allotype paraproteins

Three bacterial strains of Bifidobacterium and Clostridium sp. from patients with inflammatory bowel disease (I.B.D.) and Streptococcus pneumoniae from a patient with pneumonia were identified to produce extracellular proteases cleaving IgA into Fab and Fc fragments. Although the proteases from the Bifidobacterium and the Streptococcus pneumoniae showed the characteristics of typical IgA1 proteases, cleaving the IgA of only the IgA1 subclass, the protease from Clostridium sp. revealed a dual substrate specificity, in that it cleaved both IgA1 and IgA2 of the A2m(1) allotype. The latter protease, however, did not show any activity with respect to the IgA2 of the A2m(2) allotype. Fc fragments isolated from the IgA1 and the IgA2 A2m(1) by digestion with the Clostridium sp. protease were identified to have an identical amino terminal residue of valine. The site of cleavage in both the alpha 1 and the alpha 2 of A2m(1) by the protease was assumed to be an identical peptide bond at Pro(221)-Val(222), which is a common one present just before the hinge of both the alpha 1 and the alpha 2 of the A2m(1) but not of the alpha 2 of the A2m(2). The protease was sensitive to ethylene-diamino tetraacetic acid, a chelating agent, similar to other already reported IgA1 proteases.