Mycobacterium paratuberculosis DNA in Crohn's disease tissue

Johne's disease and milk: do consumers need to worry?

Mycobacterium paratuberculosis, an acid-fast bacillus that causes enteritis in ruminants, has been suggested as an etiological agent of Crohn's disease in humans. The mode of transmission is unclear; however, some evidence suggests that humans may become infected via contaminated milk. Currently, it is not known whether commercial pasteurization effectively kills M. paratuberculosis in contaminated raw milk. Using a laboratory-scale pasteurizer unit designed to simulate the high-temperature, short-time method (72 degrees C, 15 sec) currently used by commercial dairies, we previously demonstrated that treatment of raw milk inoculated with 10(4) to 10(6) cfu of M. paratuberculosis/ml reduced numbers to an undetectable level. However, M. paratuberculosis is an intracellular pathogen that resides within the macrophages of the host and evades destruction. We subsequently performed further experiments examining heat treatment of milk inoculated with mammary gland macrophages containing ingested M. paratuberculosis. Heat treatment of these samples under high-temperature, short-time conditions demonstrated that the macrophage does not protect the organism because we were unable to recover any viable M. paratuberculosis from the samples. Conversely, other researchers have demonstrated that a residual population of M. paratuberculosis may survive heat treatment of milk. In addition, a recent news report stated that viable M. paratuberculosis organisms have been cultured from retail-ready milk in Ireland. A summary of past and current studies concerning this issue along with a discussion of methodologies used to recover M. paratuberculosis from experimentally inoculated milk will be presented in this paper.

Open label trial of oral clarithromycin in active Crohn's disease

BACKGROUND

Crohn's disease seems likely to be due in some way to bacteria. Clarithromycin is a broad spectrum macrolide antibiotic with good penetration into macrophages and may be effective in eradicating the organisms that are presumed to be at the centre of the granulomatous reaction in Crohn's disease.

METHODS

Twenty-five patients with active Crohn's disease were treated with oral clarithromycin 250 mg b.d. in an open label study. Treatment was for an initial 4-week period, continued to 12 weeks in patients who had shown a partial or complete response. The patients had a median age of 30 years (range 17-72), and disease duration of 5 years (range 2 months-28 years); 14 had ileocolonic, four small bowel, seven colonic disease and 10 had previous resections. Twenty patients were receiving a 5-ASA preparation, 15 corticosteroids (prednisolone median dose 10 mg range 2-30 mg) and nine azathioprine. All patients receiving corticosteroids or azathioprine had been on unchanged treatment for at least 12 weeks.

RESULTS

Median pre-treatment Harvey Bradshaw index (HBI) was 9 (range 5-16) and median serum C-reactive protein was 21.5 mg/L (range < 5-117). By 4 weeks the median HBI had decreased to 5 (range 0-18) (P < 0.001) and median CRP to 17 mg/L (range < 5-157) (P=0.16). Sixteen patients (64%) had at least a 3 point fall in HBI and remission (defined as a HBI less than or equal to 4) was achieved in 12 patients (48%). By 12 weeks median HBI was 5 (range 0-18) (P < 0.001) and median CRP was 14.5 mg/L (range < 5-157) (P=0.05). Eleven of the 25 patients studied continued on oral clarithromycin after 12 weeks for a median of 28 weeks (range 20-60). Eight (73%) remained in remission on treatment. When treatment with clarithromycin was stopped three remained in remission and five relapsed after a median of 5 months (range 4-9). Two patients withdrew due to non-serious side-effects. Treatment was well tolerated in the remaining patients.

CONCLUSION

This open label study has shown an impressive response to clarithromycin in a group of patients with active Crohn's disease, many of whom had been resistant to other therapy. A formal randomized controlled trial of clarithromycin in active Crohn's disease is needed.

A meta-analysis of antimycobacterial therapy for Crohn's disease

OBJECTIVE

Various therapies have been studied for the treatment of Crohn's disease, including antimycobacterial therapy. Meta-analysis was used to evaluate the effect of antimycobacterial therapy in patients with Crohn's disease.

METHODS

Randomized, controlled trials comparing antimycobacterial therapy with placebo were identified. Key outcome data were abstracted and the results were pooled to yield odds ratios for maintenance of remission in treated versus control groups.

RESULTS

A total of eight randomized trials were identified. Six trials were fully published and were included in the primary analysis. Two trials used antimycobacterial therapy in combination with corticosteroids to induce remission in patients with active Crohn's disease, followed by maintenance therapy with antimycobacterial agents. In these trials, control patients received corticosteroids to induce remission but no antimycobacterial therapy. Pooling of these trials yielded an odds ratio of maintenance of remission in treatment versus control of 3.37 (95% confidence interval [CI], 1.38-8.24) in favor of antimycobacterial therapy. The remaining four trials used antimycobacterial therapy combined with standard therapy in patients with Crohn's disease. In these trials, control patients received standard therapy alone. Pooling of these trials yielded an odds ratio of maintenance of remission in treatment versus control of 0.69 (95% CI, 0.39-1.21) in favor of standard therapy.

CONCLUSIONS

These results suggest that antimycobacterial therapy is effective in maintaining remission in patients with Crohn's disease after a course of corticosteroids combined with antimycobacterial therapy to induce remission. Treatment of Crohn's disease with antimycobacterial therapy does not seem to be effective without a course of corticosteroids to induce remission. Because of the small number of studies included in this meta-analysis, the results should be interpreted with caution.

Alkyl hydroperoxide reductases C and D are major antigens constitutively expressed by Mycobacterium avium subsp. paratuberculosis

Antigens characteristic for Mycobacterium avium subspecies paratuberculosis were identified by crossed immunoelectrophoresis (CIE) and by absorbing out cross-reactive antigens by using a polyclonal and polyvalent Mycobacterium avium subspecies avium antiserum. Two antigens were present in M. avium subsp. paratuberculosis and not detected in Mycobacterium avium subsp. avium. They were identified as antigens 17 and 20 in a CIE reference system for M. avium subsp. paratuberculosis antigens. Purified antigen 20 was identified as alkyl hydroperoxide reductase C (AhpC) while the N-terminal part of purified antigen 17 showed 80% homology with alkyl hydroperoxide reductase D (AhpD) of Mycobacterium tuberculosis. AhpC had a nonreduced mobility in sodium dodecyl sulfate-polyacrylamide gel electrophoresis corresponding to a molecular mass of 45 kDa and is probably a homodimer linked with disulfide bridges in its native form. AhpD had a mobility corresponding to 19 kDa. Monospecific rabbit antiserum against AhpC and AhpD reacted with 9 strains of M. avium subsp. paratuberculosis but not with 20 other mycobacterial strains except for a Mycobacterium gordonae strain, against which a weak cross-reactive band was produced. Goats experimentally infected with M. avium subsp. paratuberculosis had strong gamma interferon (IFN-gamma) responses toward both AhpC and AhpD, and they also had antibodies against AhpC. The ability of AhpC and AhpD to induce IFN-gamma production shows that these proteins potentially could be used in future vaccines or in diagnostic assays. These results further show that AhpC and AhpD are immunologically important proteins which are constitutively and highly expressed in M. avium subsp. paratuberculosis without the bacteria being submitted to oxidative stress and that the specificities of antigens can be a matter of different levels of protein expression in various species as well as distinct structural differences.

Identification of a novel mycobacterial histone H1 homologue (HupB) as an antigenic target of pANCA monoclonal antibody and serum immunoglobulin A from patients with Crohn's disease

pANCA is a marker antibody associated with inflammatory bowel disease (IBD), including most patients with ulcerative colitis and a subset with Crohn's disease. This study addressed the hypothesis that pANCA reacts with an antigen(s) of microbial agents potentially relevant to IBD pathogenesis. Using a pANCA monoclonal antibody, we have previously identified the C-terminal basic random-coil domain of histone H1 as a pANCA autoantigen. BLAST analysis of the peptide databases revealed H1 epitope homologues in open reading frames of the Mycobacterium tuberculosis genome. Western analysis of extracts from six mycobacterial species directly demonstrated reactivity to a single, conserved approximately 32-kDa protein. Direct protein sequencing, followed by gene cloning, revealed a novel 214-amino-acid protein, an iron-regulated protein recently termed HupB. Sequence analysis demonstrated its homology with the mammalian histone H1 gene family, and recombinant protein expression confirmed its reactivity with the 5-3 pANCA monoclonal antibody. Binding activity of patient serum immunoglobulin G (IgG) to HupB did not correlate with reactivity to histone H1 or pANCA, indicating the complex character of the pANCA antigen. However, anti-HupB IgA was strongly associated with Crohn's disease (P < 0.001). These findings indicate that the 5-3 pANCA monoclonal antibody detects a structural domain recurrent among mycobacteria and cross-reactive with a DNA-binding domain of histone H1. The association of HupB-binding serum IgA with IBD provides new evidence for the association of a mycobacterial species with Crohn's disease.

Mycobacteria distenct from Mycobacterium avium subsp. paratuberculosis isolated from the faeces of ruminants possess IS900-like sequences detectable IS900 polymerase chain reaction: implications for diagnosis

PCR targeting the 5' end of IS 900 has been considered specific for identification of Mycobacterium avium subsp. paratuberculosis and is frequently applied to confirm the presence of this organism in the diagnosis of Johne's disease. IS 900 PCR has also been applied to studies of the aetiology of Crohn's disease. Mycobacterium spp. isolated from the faeces of 3 clinically normal animals in 2 Australian states appeared not to be M. paratuberculosis but were positive by IS 900 PCR. The isolates were characterized using mycobactin dependency, biochemical tests, IS 900 and 16 S rRNA sequencing and restriction fragment length polymorphism (RFLP) using IS 900 as probe. DNA sequencing confirmed that the isolates had between 71% and 79% homology with M. paratuberculosis in the region of IS 900 amplified, were most closely related to Mycobacterium scrofulaceum, and confirmed the usefulness of restriction enzyme analysis of amplified product to identify the false positive results. RFLP analysis with Bst Ell detected three to five copies of the IS 900 -like element in the isolates. These were located in molecular weight fragments that were clearly different to IS 900 in previously characterized strains of M. paratuberculosis. It is likely that these isolates are environmental mycobacteria. Southern blotting with an internal probe is unlikely to provide differentiation of M. paratuberculosis from these organisms. We recommend the adoption of restriction endonuclease analysis of IS 900 PCR product as a routine precaution to prevent the reporting of false positive IS 900 PCR results.

Medical options for treating Crohn's disease in adults: focus on antitumor necrosis factor-alpha chimeric monoclonal antibody

Crohn's disease is a chronic inflammatory disorder that can present with symptoms throughout the gastrointestinal system. Though the etiology of Crohn's disease is unknown, genetic and environmental factors seem to play a role. An imbalance of proinflammatory versus antiinflammatory cytokines is responsible for many of the symptoms. Tumor necrosis factor alpha, a potent proinflammatory cytokine, plays a particularly important role. Several treatment modalities for Crohn's disease exist, recently including antitumor necrosis factor chimeric monoclonal antibody (cA2). Treatment for Crohn's disease, including data on the safety and efficacy of cA2, will be reviewed.

Mycobacterium paratuberculosis detection in bovine feces is improved by coupling agar culture enrichment to an IS900-specific polymerase chain reaction assay

The feasibility of coupling an agar culture enrichment step with gene amplification (ACE-PCR) as a means to improve turnaround time and detect Mycobacterium paratuberculosis (Mpt) in the presence of contaminants was investigated. Fecal samples from 463 Pennsylvania dairy cows were cultured in duplicate sets. One replicate from each set was processed and interpreted according to standard culture (SC) protocol, whereas cultures from the second replicate were harvested at 6 weeks postinoculation; DNA extracts from the harvested material were evaluated by a polymerase chain reaction (PCR) test for the Mpt-specific IS900 gene. One hundred seventy-six of 463 culture sets were positive by either method. One hundred sixty-five of these (94%) were ACE-PCR positive, and 151 (86%) were positive by SC. Eleven SC-positive samples were ACE-PCR negative, and 9 ACE-PCR-positive samples were negative by SC; these discrepancies could be a consequence of a low organism burden (< or = 5 organisms/g) or slow growth rate of Mpt in cultures of these samples. One hundred thirty-nine of 463 culture sets (30%) were reported as inconclusive because of culture contamination according to SC protocol; 16 of these (11.5%) were ACE-PCR positive. Seventy-four ACE-PCR-positive sets (42% of all positives) were negative or inconclusive by SC at 6 weeks postinoculation. Agar culture enrichment prior to IS900 PCR testing significantly improves Mpt culture turnaround time and sensitivity.

Enhanced intestinal expression of heat shock protein 70 in patients with inflammatory bowel diseases

Heat shock protein (Hsp) 70 is stress-inducible and exhibits both protective and antigenic properties. This study investigated the mucosal expression of the constitutive (Hsp70c) and inducible form (Hsp70i) as well as antibodies against human Hsp70 in inflammatory bowel disease and controls. Biopsies were assessed by immunoblot and immunofluorescence, resection specimens by immunohistochemistry, and mucosal antibody content by isoelectric focusing. Compared to controls, expression of Hsp70 was enhanced in ulcerative colitis (P<0.05), less so in Crohn's disease and infectious colitis. Strong epithelial staining was found for Hsp70c and Hsp70i in both diseases. Mucosal and submucosal mononuclear cells showed enhanced Hsp70c expression in Crohn's disease and to a lesser degree in ulcerative colitis. Antibodies of isotypes A or M were detected in nearly all patients and controls. The different pattern of Hsp70 expression in Crohn's disease compared to ulcerative colitis points to a distinct protective and immunological function, whereas a role in autoimmunity seems unlikely.

Epidemiological study of paratuberculosis in wild rabbits in Scotland

A survey of 22 farms confirmed the presence of paratuberculosis in wild rabbits in Scotland. Regional differences were apparent in the prevalence of the disease in rabbits, with a significantly higher incidence occurring in the Tayside region. Statistical analysis showed a significant relationship between a previous history or current problem of paratuberculosis in cattle and the presence of paratuberculosis in rabbits on the farms. Molecular genetic typing techniques could not discriminate between selected rabbit and cattle isolates from the same or different farms, suggesting that the same strain may infect and cause disease in both species and that interspecies transmission may occur. The possibility of interspecies transmission and the involvement of wildlife in the epidemiology of paratuberculosis have important implications for the control of the disease.

Single PCR and nested PCR with a mimic molecule for detection of Mycobacterium avium subsp. paratuberculosis

Mycobacterium avium subsp. paratuberculosis is the causative agent of Johne's disease in ruminants. The current methods for detection of M. avium subsp. paratuberculosis are slow and insensitive. We report the use of a polymerase chain reaction (PCR) based on IS900 to confirm growth of M. avium subsp. paratuberculosis in primary bacterial cultures from bovine tissue and fecal samples. The use of PCR on single colonies reduced the time for analysis by 2 months compared with conventional methods. We also report the development of a nested PCR based on IS900 and the development of a positive internal control molecule, a so-called mimic. The system was tested with spiked tissue samples, and the sensitivity was estimated to 10 CFU per sample. Seventeen tissue samples, previously found M. avium subsp. paratuberculosis positive by microbiological culture, were analyzed by nested PCR and the efficiency of the PCR was checked by co-amplification of the mimic. Absence of the mimic amplicon indicated inhibition of the amplification. Ten of the samples were positive and five were negative, as judged from the presence or absence of the IS900 PCR product. Two negative samples could not be judged because of inhibition revealed by mimic molecules. It was concluded that the nested PCR, together with the mimic, could be a useful tool in screening tissue materials.

Chronic infection in the aetiology of atherosclerosis--focus on Chlamydia pneumoniae

An inflammatory basis to atherosclerosis is now accepted. It remains plausible (but unproven) that common infectious agents may contribute to the inflammatory signal, and hence the development (and/or progression of atherosclerosis and its clinical sequelae. Of the candidate microorganisms implicated, Chlamydia pneumoniae has emerged as the most likely pathogen to have a casual role. Evidence for this is based on sero-epidemiological, pathological and laboratory-based evidence, in addition to early animal models and small-scale antibiotic studies. A past decade of research has now culminated in prospective antibiotic intervention trials in coronary heart disease to be conducted. The results of these studies should help to finally determine whether infection with C. pneumoniae is a pathogenetic factor in atherosclerosis, and whether antibiotic therapy has a role in the secondary prevention of coronary heart disease.

A low G+C content genetic island in Mycobacterium avium subsp. paratuberculosis and M. avium subsp. silvaticum with homologous genes in Mycobacterium tuberculosis

The technique of representation difference analysis PCR has been applied to find genes specific to Mycobacterium avium subsp. paratuberculosis. This generated a 671 bp fragment which was used to isolate a larger genetic element found in the enteric pathogens M. avium subsp. paratuberculosis and M. avium subsp. silvaticum but which was absent from the very closely related and relatively benign M. avium subsp. avium. This element, designated GS, is greater than 6.5 kbp in length and has a G+C content 9 mol% lower than other genes from this species. There is a previously uncharacterized insertion sequence associated with one end. The GS element encodes five ORFs in M. avium subsp. paratuberculosis and M. avium subsp. silvaticum, all of which have counterparts encoded in Mycobacterium tuberculosis. Database searches revealed homologues for these ORFs in a number of bacterial species, predominantly Gram-negative organisms, including a number of enteric pathogens. These homologous genes encode functions related to LPS or extracellular polysaccharide biosynthesis. This element has a number of features in common with pathogenicity islands such as its low G+C content, an association with a putative insertion sequence and a grouping of genes of related function with a possible link to virulence. No direct link to pathogenicity has been shown but GS may belong to a group of related 'genetic islands' and represents the first such element to be identified in mycobacteria.

Microbiology of the intestinal lymph follicle: a clue to elucidate causative microbial agent(s) in Crohn's disease

It has been suggested that microbial agent(s) are involved in the onset of Crohn's disease. None of the candidates, however, has been unequivocally demonstrated to be a causative agent. The macroscopically earliest lesion takes place in the lymph follicle, irrespective of the initial attack or relapse in Crohn's disease. Human leucocyte antigen-DR (HLA-DR) antigens are expressed on the epithelium around the lymph follicle even in areas endoscopically uninvolved in Crohn's disease. These observations make the lymph follicle critical in the onset of Crohn's disease. The lymph follicle is a port of entry of a variety of microbial agent(s), leading to the speculation that microbial agent(s) exist in the lymph follicle. Polymerase chain reaction (PCR) using universal primers designed from conserved regions of bacterial ribosomal RNA or techniques such as representational difference analysis, may well identify microbial agent(s) in the lymph follicle that are specific to Crohn's disease. The existence of bacteria in the lymph follicle is here indicated by preliminary studies.

Human exposure to Mycobacterium paratuberculosis via pasteurised milk: a modelling approach

Paratuberculosis is a disease of cattle caused by infection with Mycobacterium paratuberculosis, and it has been suggested that this bacterium may also play a role in the aetiology of Crohn's disease in humans. M paratuberculosis is shed in the milk and may be able to survive pasteurisation. Therefore, people may be exposed to it by the consumption of pasteurised milk. The risk of such exposure has been analysed using a modelling approach and the model has been used to evaluate the effects of intervention measures at different points in the potential route of transmission. On the basis of data from the literature and expert opinion, an initial point estimate of the exposure level of about 0-5 cfu/litre pasteurised milk was derived, mainly due to milk from clinically affected animals. The model indicates the need for quantitative data on variations in the shedding rates of M paratuberculosis in faeces and milk, and the levels of faecal contamination of milk. Such data are essential for a proper analysis of potential exposure, and may result in a 100-fold increase in the estimated median level of exposure.

Intestinal expression of human heat shock protein 90 in patients with Crohn's disease and ulcerative colitis

Heat shock proteins are induced by several stress factors and are potential antigens in autoimmune disorders. Expression of heat shock protein 90 (HSP 90) was investigated in patients with inflammatory bowel disease and normal controls. We combined western blot analysis with laser densitometry for quantitation. Localization of HSP 90 was investigated by immunohistochemistry. Western blots showed a significant mucosal expression of HSP 90, which was comparable in patients and controls. There was also no difference between normal and inflamed mucosa in inflammatory bowel disease. In immunohistochemical staining studies, HSP 90 was detected in epithelial cells, mononuclear cells, giant cells, nerve cells, and endothelial cells of small vessels. There was no difference in the intensity of staining or localization in patients with inflammatory bowel disease compared to controls. These findings render a potential protective or immunogenic function of HSP 90 in inflammatory bowel disease unlikely.

Thermal tolerance of Mycobacterium paratuberculosis

D values (decimal reduction time; the time required to kill 1 log concentration of bacteria) were determined for both human and bovine strains (Dominic, Ben, BO45, and ATCC 19698) of Mycobacterium paratuberculosis in 50 mM lactate solution (pH 6.8) and in milk at four temperatures (62, 65, 68, and 71 degrees C). Viable M. paratuberculosis organisms were quantified by a radiometric culture method (BACTEC). Thermal death curves for the M. paratuberculosis strains tested were generally linear, with R2 of > or = 0.90, but a few curves (R2, 0.80 to 0.90) were better described by a quadratic equation. The human strains (Dominic and Ben) had similar D values in milk and in lactate solution. However, D values for the bovine strains (BO45 and ATCC 19698) were significantly different depending on the menstruum. D values for low-passage clinical strains (Dominic, Ben, and BO45) were lower than those of the high-passage laboratory strain (ATCC 19698). The D value based on pooled data for clinical strains of M. paratuberculosis in milk at 71 degrees C (D71 degrees C) was 11.67 s. Pooled D62 degrees C, D65 degrees C, and D68 degrees C of clinical M. paratuberculosis strains in milk were 228.8, 47.8, and 21.8 s, respectively. The Z value (the temperature required for the decimal reduction time to traverse 1 log cycle) of clinical strains in milk was 7.11 degrees C. The D values of clumped and single M. paratuberculosis cells were not significantly different. The D values of all M. paratuberculosis strains tested were considerably higher than those published for Listeria, Salmonella, and Coxiella spp. and estimated for Mycobacterium bovis, indicating that M. paratuberculosis is more thermally tolerant. This study supports the premise that M. paratuberculosis may survive high-temperature, short-time pasteurization when the initial organism concentration is greater than 10(1) cells/ml.

Pathogenesis of Crohn's disease

In the absence of a single initiating aetiological factor, most workers envisage Crohn's disease as the manifestation of poorly regulated immune and inflammatory processes within the gut wall. Initially these responses may arise as a response to common antigens associated with the gut--bacterial products being amongst the most obvious candidates. In genetically predisposed individuals there is overexpression both of local immune response mechanisms in the gut wall (T-cells, B-cells and macrophages) and of systemic inflammatory cells (predominantly polymorphonuclear leukocytes), which are attracted into the inflamed gut through activation of adhesion molecules on the vascular endothelium. As a consequence a large number of pro-inflammatory processes are expressed in the gut wall, inadequately checked by the normal counter-inflammatory processes that should serve to limit inflammation. Defining the relative importance of the individual processes, and identifying critical steps that could be inhibited or enhanced for therapeutic purposes, is a major challenge of Crohn's disease research.

Role of Mycobacterium paratuberculosis in Crohn's disease: a prospective, controlled study using polymerase chain reaction

PURPOSE

Mycobacterium paratuberculosis has been proposed as a causative agent in patients with Crohn's disease. The purpose of this study was to determine whether M. paratuberculosis was present in tissue from patients with Crohn's disease in a defined geographic area.

METHODS

We prospectively evaluated, using polymerase chain reaction and culture, whether M. paratuberculosis was present in 44 specimens (37 from intestinal mucosal biopsies and 7 from surgical resections) from patients with Crohn's disease, ulcerative colitis, or normal colonic mucosa.

RESULTS

Of the 25 specimens tested from the 21 Crohn's patients, only 1 positive specimen was noted, whereas the 8 specimens from the 5 ulcerative colitis patients and the 11 specimens from the 11 control patients failed to demonstrate a positive result with polymerase chain reaction. Cultures of all specimens revealed no growth of M. paratuberculosis.

CONCLUSION

M. paratuberculosis was only rarely detected in biopsy or surgical specimens from patients with Crohn's disease. These results do not support a common causative role of M. paratuberculosis in Crohn's disease.

Johne's disease: a hidden threat

Paratuberculosis, which is also known as Johne's disease, is a chronic, progressive enteric disease of ruminants caused by infection with Mycobacterium paratuberculosis. Cattle become infected with M. paratuberculosis as calves but often do not develop clinical signs until 2 to 5 yr of age. The clinical disease is characterized by chronic or intermittent diarrhea, emaciation, and death. Although animals with clinical disease are often culled from the herd, animals with subclinical paratuberculosis may cause economic losses because of reduced milk production and poor reproductive performance. Although the economic impact of paratuberculosis on the national cattle industry has not been determined, it is estimated to exceed $1.5 billion/yr. The diagnosis of subclinical paratuberculosis is difficult. Bacteriologic culture is the most definitive method of diagnosis, but culture is time consuming and labor intensive. Serological assays are not very useful because animals do not develop an antibody response until the clinical stages of disease. Development of assays to measure cell-mediated immunity is critical to accurate detection of paratuberculosis in subclinically infected animals. Although not considered a zoonotic agent, M. paratuberculosis has been identified in intestinal biopsy tissue from patients with Crohn's disease, an inflammatory enteritis in humans. Currently, the potential human health risk is being addressed by research evaluating pasteurization of dairy products in the US.

Mycobacterium paratuberculosis: a potential food-borne pathogen?

Mycobacterium paratuberculosis commonly infects dairy cattle, leading to Johne's disease, which is also known as paratuberculosis. The infection is chronic progressive, and incurable. As the infection progresses, excretion of M. paratuberculosis in feces and milk occurs, and the bacterium spreads through the blood to multiple internal organs. Consequently, raw products originating from cattle may harbor M. paratuberculosis. Thermal treatments, such as pasteurization, are commonly relied on to kill food-borne bacterial pathogens that can infect humans. The small number of studies conducted to determine the thermal resistance of M. paratuberculosis suggest that it is less susceptible to destruction by heat killing than are milkborne zoonotic bacterial pathogens such as Listeria spp. or Mycobacterium bovis. Published reports concerning the thermal resistance of M. paratuberculosis in milk are reviewed herein, and key issues concerning the efficacy of pasteurization for elimination of M. paratuberculosis from milk are summarized.

Metastatic Crohn's disease involving the penis

Metastatic Crohn's disease is a rare complication in Crohn's disease and there have been only several cases of metastatic Crohn's disease involving the penis. We report one such case. A 22-year-old male student developed anal pain and alternative constipation and diarrhea in December, 1985, followed by diarrhea and lower abdominal pain in January, 1986. He was diagnosed as having Crohn's disease of ileocolitis type. He was admitted to our hospital in July, 1987 because of exacerbation of Crohn's disease. He had anal tags. Soon after admission, two red swollen lesions with central ulcer and erosions were demonstrated at the eversion of the foreskin adjacent to coronal sulcus. Histology of the lesions revealed granulomas with epithelioid cells and giant cells. The lesion responded to a topical steroid. Eight cases of metastatic Crohn's disease involving the penis are briefly reviewed.

Search for Mycobacterium paratuberculosis DNA in orofacial granulomatosis and oral Crohn's disease tissue by polymerase chain reaction

BACKGROUND

Although intestinal Crohn's disease has long been suspected to have a mycobacterial cause, possible mycobacterial involvement in orofacial granulomatosis (OFG) and oral lesions of Crohn's disease has not yet been investigated.

AIMS

As the slow growing Mycobacterium paratuberculosis has been implicated in the aetiology of intestinal Crohn's disease, the potential involvement of this mycobacterial species in OFG and oral lesions of Crohn's disease was investigated.

PATIENTS

To attempt detection of the organism in OFG and oral Crohn's disease tissue samples, a polymerase chain reaction (PCR) assay was used on archival formalin fixed, paraffin wax embedded oral tissue sections from 30 patients with OFG, seven with Crohn's disease, and 12 normal controls.

METHODS

The PCR assay used was based on primers targeting the 5' region of the multicopy IS900 DNA insertion element of the M paratuberculosis genome. In order to achieve maximum sensitivity, two rounds of PCR were carried out and amplicons confirmed by Southern blot hybridisation to a digoxigenin labelled IS900 DNA probe.

RESULTS

None of the OFG and oral lesions of Crohn's disease samples were positive for M paratuberculosis and all normal controls were also negative.

CONCLUSIONS

These results suggest that M paratuberculosis may not be a major aetiological agent in OFG or oral Crohn's disease lesions, although the use of paraffin wax embedded tissue as opposed to fresh tissue as a sample source could underestimate the true prevalence of the organism.

Detection of Mycobacterium avium subsp. paratuberculosis in ovine tissues and blood by the polymerase chain reaction

A direct polymerase chain reaction (PCR) test was applied to DNA extracted from blood, liver, ileocecal lymph node and ileum from twelve ewes in poor condition with histologically confirmed paratuberculosis and ten clinically normal sheep which had no evidence of paratuberculosis. The assay was compared with four serological tests: complement fixation test (CFT), gel diffusion test (AGID) and two enzyme-linked immunosorbent assays (ELISA). The PCR detection rate of Mycobacterium avium subsp. paratuberculosis, when results of single tests were interpreted in duplicate, was 72% for ileocecal lymph node, 90% for liver, and 100% for ileum in sheep with confirmed paratuberculosis. A single PCR test detected the target DNA in 66% of 0.5 ml blood samples. Sensitivities of serological tests compared with histological diagnosis were: 33% for CFT, 66% for AGID, 75% for the Central Animal Health Laboratory (CAHL) ELISA, and 83% for the 'modified' Commonwealth Serum Laboratories (CSL) ELISA. The PCR assay gave no positive reaction in samples collected from 10 sheep considered to be free of paratuberculosis. Similarly, all four serological tests were also 100% specific. The results raise some hope for the development of a PCR-based test using liver biopsy specimens, or possibly blood, in the diagnosis of paratuberculosis in sheep.

A multiplex polymerase chain reaction assay for the detection of Mycobacterium paratuberculosis DNA in Crohn's disease tissue

BACKGROUND

Mycobacterium paratuberculosis is implicated as a possible cause of Crohn's disease. However, due to lack of an appropriate diagnostic method, this has been a subject of significant controversy. Our aim was therefore to develop a multiplex polymerase chain reaction (MPCR) for the detection of M. paratuberculosis DNA in Crohn's disease tissue.

METHODS

Biopsy samples were collected by endoscopic forceps from terminal ileum, and genomic DNA was isolated. M. paratuberculosis-specific marker genes were amplified by using the present MPCR method.

RESULTS

Here we report a new MPCR for detection of M. paratuberculosis DNA in Crohn's disease tissue. In this technique two genetic markers, IS900 and a newly described specific marker of MP2, were amplified in a single tube simultaneously. The method was evaluated using biopsy specimens from 10 Crohn's disease patients, 6 ulcerative colitis patients, and 21 irritable bowel syndrome patients. The patients were characterized by using standard clinical and histologic observations. The present MPCR method could not detect M. paratuberculosis DNA in the biopsy specimens. However, the marker genes were amplified from the samples that were spiked with M. paratuberculosis before DNA extraction. The marker genes were also not detected in 10 closely related mycobacterial strains and human genomic DNA.

CONCLUSIONS

The present MPCR method is highly specific and can detect M. paratuberculosis DNA more reliably. These findings do not support an aetiologic role of M. paratuberculosis in Crohn's disease.

Characterization of a specific Mycobacterium paratuberculosis recombinant clone expressing 35,000-molecular-weight antigen and reactivity with sera from animals with clinical and subclinical Johne's disease

Johne's disease is a chronic enteritis of ruminants associated with enormous worldwide economic losses for the dairy cow- and goat-rearing industries. Management limitations and eradication programs for this disease have been hampered by the lack of a simple and specific diagnostic test for the detection of subclinical cases. We used a recombinant clone expressing a 35,000-molecular-weight Mycobacterium paratuberculosis antigen (p35 antigen) from a previously constructed expression library of M. paratuberculosis in Escherichia coli. The DNA fragment encoding the p35 gene hybridized only to DNA from Mycobacterium avium complex, but not to DNAs from other mycobacteria and nonmycobacterial organisms. The seroreactivity of p35 was evaluated by immunoblotting against 57 reference serum samples obtained from infected and uninfected animals. p35 was recognized by sera from 100% of animals with advanced Johne's disease (clinical stage) (12 cattle, 2 goats, and 2 sheep) and by sera from 75% of 20 cattle with early infection (subclinical stage). None of the sera from 15 M. paratuberculosis-free cows, 3 Mycobacterium bovis BCG-infected tuberculous cattle, or 3 cows artificially inoculated with multiple doses of viable M. paratuberculosis reacted with p35. The overall sensitivity, specificity, positive predictive value, and negative predictive value were 86, 100, 100, and 75%, respectively. The accuracy of p35 immunoblotting was superior to those of commercially available diagnostic tests for Johne's disease. These results suggest that the p35 recombinant protein has potential for use in the serodiagnosis of animals with Johne's disease at all stages of infection. The DNA fragment encoding p35 may also serve as a probe for identification of M. avium complex infection.

Detection of fastidious mycobacteria in human intestines by the polymerase chain reaction

The aim of this study was to determine whether difficult-to-grow mycobacteria are present in human intestines. Intestinal tissue samples were subjected to both mycobacterial culture and a polymerase chain reaction (PCR) assay. After detection by PCR, species identity was determined by hybridizing the amplified 16S rRNA gene fragments with species-specific oligonucleotides. Intestinal biopsies from 63 patients with noninflammatory bowel diseases (n = 22), Crohn's disease (n = 31), or ulcerative colitis (n = 10) were analyzed. Culture and PCR revealed mycobacteria in four (6%) and 25 (40%) samples, respectively. Samples positive by PCR were negative with all probes specific to nine common cultivable species but were positive with Mycobacterium genavense-specific probe in 68% of cases. Mycobacterial isolates were identified as Mycobacterium gordonae and Mycobacterium chelonae. Findings were similar in Crohn's disease samples compared to non-Chron's disease samples. This study shows that difficult-to-grow mycobacteria can be detected by PCR in large and similar proportions of inflamed intestinal tissue from patients with inflammatory bowel disease and intestinal tissue that appears normal from patients with noninflammatory bowel disease.

The contribution of molecular biology to Mycobacterium avium subspecies Paratuberculosis research

Molecular biology has contributed to our knowledge and understanding of the structure of Mycobacterium avium subspecies paratuberculosis and has been particularly useful in determining those components that elicit immune responses in the host or discriminate M. avium paratuberculosis from other closely related environmental mycobacteria. As such, it has made a significant impact in the field of diagnosis, and has been instrumental in the development of specific and sensitive diagnostic tests. The next decade will see exciting new developments in paratuberculosis research as a consequence of substantial advances made in the construction of gene transfer systems in mycobacteria. These will provide opportunities for applying new strategies to determine the genetic basis for pathogenesis and the mechanisms of drug resistance and will offer new prospects for the rational design of efficient vaccines.

Treatment of ulcerative colitis in the cottontop tamarin using antibody to tumour necrosis factor alpha

BACKGROUND

The aetiology and pathophysiology of ulcerative colitis remains unclear; however, there is increasing recognition of the critical role of inflammatory cytokines in the pathogenesis of this disease. Among these, tumour necrosis factor alpha (TNF alpha) seems to play an important role.

AIM

To study the effects of an engineered human monoclonal antibody to TNF alpha (CDP571) in the treatment of idiopathic ulcerative colitis in the cottontop tamarin.

METHODS

Six cottontop tamarins with confirmed ulcerative colitis received repeated doses of CDP571. Progression of disease was assessed by measuring both body weight and rectal biopsy pathology.

RESULTS

All animals showed a rapid improvement in clinical condition and rectal biopsy pathology that was maintained following completion of the therapy.

CONCLUSION

These studies indicate the efficacy of selective antibody therapy to TNF alpha for the treatment of ulcerative colitis in a primate and suggest that similar therapy in human could be of value.

The British Society of Gastroenterology Diamond Jubilee. March 1997

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A detailed lectin analysis of IgG glycosylation, demonstrating disease specific changes in terminal galactose and N-acetylglucosamine

Serum IgG from rheumatoid arthritis patients contains a decreased number of oligosaccharide structures ending in galactose and thus there is an increase in N-acetylglucosamine as the terminal sugar, compared with healthy individuals. The relationship between these two sugars varies depending on the disease examined: IgG from patients with rheumatoid arthritis, juvenile onset chronic arthritis and Crohn's disease are at one extreme, and exhibit a reciprocal galactose:N-acetylglucosamine relationship, while Sjögren's syndrome and osteoarthritis IgG are at the other extreme, exhibiting a parallel increase in the expression of both galactose and N-acetylglucosamine. These results may occur as a consequence of more than one glycosylation site which is differentially glycosylated, but more likely by changes in the level of bisecting N-acetylglucosamine.

Enteric Microflora in IBD: Pathogens or Commensals?

: Both pathogenic and normal enteric microflora can induce and perpetuate chronic intestinal inflammation with systemic manifestations in genetically susceptible hosts. At the present time, there is no convincing indication that the majority of cases of ulcerative colitis or Crohn's disease is caused by persistent infection by Mycobacterium paratuberculosis, measles, Listeria monocytogenes, or Helicobacter species, but this possibility remains a valid hypothesis. Transient infection with any of a number of pathogens including upper respiratory tract infections and common enteric pathogens could provide one of the environmental triggers that initiate or reactivate IBD, which is then perpetuated in susceptible hosts by resident (not pathogenic) commensal luminal bacteria. Recent results in animal models demonstrate the absence of colitis, gastritis, and arthritis in a sterile (germ-free) environment, showing the importance of resident bacteria as persistent antigenic stimuli in the genetically susceptible hosts. Furthermore, there is an indication that not all normal luminal bacteria have equal capacities to induce mucosal injury, since some species can induce inflammation (Bacteroides), some are neutral (E. coli) and others may be protective (Lactobacilli). These observations have important therapeutic implications, such that altering luminal bacterial components and thereby decreasing the persistent antigenic drive offer alternative or adjuvant approaches to ongoing efforts to block mucosal immune responses to these stimuli.

Detection of Mycobacterium avium complex in cerebrospinal fluid of a sarcoid patient by specific polymerase chain reaction assays

The etiology of sarcoidosis is unknown, but it has long been suspected to be mycobacterial. In the present study, we used 4 mycobacterial species-specific polymerase chain reaction assays on cerebrospinal fluid obtained from a patient with neurosarcoidosis. Positive hybridization was observed with both the Mycobacterium avium complex probe and the insertion element IS900-specific probe that has been found in M. paratuberculosis species. There was no hybridization with M. tuberculosis or M. avium woodpigeon strain-specific probes. This case report demonstrates that M. paratuberculosis or some closely related M. avium spp which perhaps also carry IS900, or contain closely related DNA sequences, are associated with at least some cases of sarcoidosis disease.

On the etiology of Crohn disease

Crohn disease (CD) is a chronic, panenteric intestinal inflammatory disease. Its etiology is unknown. Analogous to the tuberculoid and lepromatous forms of leprosy, CD may have two clinical manifestations. One is aggressive and fistulizing (perforating), and the other is contained, indolent, and obstructive (nonperforating) [Gi]-berts, E. C. A. M., Greenstein, A. J., Katsel, P., Harpaz, N. & Greenstein, R. J. (1994) Proc. Natl. Acad. Sci. USA 91, 12721-127241. The etiology, if infections, may be due to Mycobacterium paratuberculosis. We employed reverse transcription PCR using M. paratuberculosis subspecies-specific primers (IS 900) on total RNA from 12 ileal mucosal specimens (CD, n = 8; controls, n = 4, 2 with ulcerative colitis and 2 with colonic cancer). As a negative control, we used Myobacterium avium DNA, originally cultured from the drinking water of a major city in the United States. cDNA sequence analysis shows that all eight cases of Crohn's disease and both samples from the patients with ulcerative colitis contained M. paratuberculosis RNA. Additionally, the M. avium control has the DNA sequence of M. paratuberculosis. We demonstrate the DNA sequence of M. paratuberculosis from mucosal specimens from humans with CD. The potable water supply may be a reservoir of infection. Although M. paratuberculosis signal in CD has been previously reported, a cause and effect relationship has not been established. In part, this is due to conflicting data from studies with empirical antimycobacterial therapy. We conclude that clinical trials with anti-M. paratuberculosis therapy are indicated in patients with CD who have been stratified into the aggressive (perforating) and contained (nonperforating) forms.

IS900 PCR to detect Mycobacterium paratuberculosis in retail supplies of whole pasteurized cows' milk in England and Wales

IS900 PCR for Mycobacterium paratuberculosis was applied to cream, whey, and pellet fractions of centrifuged whole cows' milk. The test and simultaneous control reactions gave correct results for spiked milk and for native milk samples obtained directly from M. paratuberculosis-free, subclinically infected, and clinically infected cows. The test was then applied to units of whole pasteurized cows' milk widely obtained from retail outlets throughout central and southern England from September 1991 to March 1993. With peak periods in January to March and in September to November, when up to 25% of units were affected, an overall 22 of 312 samples (7%) tested positive for M. paratuberculosis. In 18 of the 22 positive samples (81%), the PCR signal segregated to the cream or pellet fractions or both, consistent with the presence of intact mycobacteria. Nine of 18 PCR-positive milk samples (50%) and 6 of 36 PCR-negative milk samples (16%) yielded long-term liquid cultures which tested positive for M. paratuberculosis after 13 to 40 months of incubation, despite overgrowth by other organisms. Taken together with data on the prevalence of M. paratuberculosis infection in herds in the United Kingdom, the known secretion of M. paratuberculosis in milk from subclinically infected animals, and the inability of laboratory conditions simulating pasteurization to ensure the killing of all these slowly growing or unculturable organisms, there is a high risk, particularly at peak times, that residual M. paratuberculosis will be present in retail pasteurized cows' milk in England.

Differences in the kinetics of T cell accumulations in C3H/HeN (Bcg-resistant) and C57BL/6 (Bcg-susceptible) mice infected with Mycobacterium paratuberculosis

The accumulation of various T cell subsets in Bcg-susceptible (C57BL/6) and- resistant (C3H/HeN) strains of mice were compared following an intraperitoneal infection with Mycobacterium paratuberculosis. Groups of mice from both strains were killed at 3, 5, 10, 15, 30, and 150 days after infection and lymphocytes were harvested from the peritoneal exudate cells (PEC), spleen, intestinal epithelial lymphocytes (IEL), lamina propria lymphocytes (LPL), Peyer's patches, and mesenteric lymph node (MLN) and labelled with monoclonal antibodies to CD3, CD4, CD8, gamma delta TCR, CD25, and CD44 for flow cytometric analysis. Uninfected C3H/HeN mice had higher proportions of CD4+ cells in the spleen, MLN, LPL, IEL, and Peyer's patches, while uninfected C57BL/6 mice had higher proportions of CD8+ and/or gamma delta T cells. Significant increases in accumulation of CD8+ and gamma delta T cells were detected in the peritoneum and other tissues in both strains of mice after infection. Higher CD4/CD8 ratios were observed in most lymphoid tissues of C3H/HeN mice, while increased proportions of CD8+ and/or gamma delta T cells were present in C57BL/6 mice. These results indicate that significant differences in T cell profiles exist between these two strains of mice, both inherently and in response to infection with M. paratuberculosis. Innately lower levels of CD4+ cells and/or higher percentages of CD8+ and gamma delta T cells may play a role in the increased suspectibility of C57BL/6 mice to infection with M. paratuberculosis.

Identification of Mycobacterium avium complex in sarcoidosis

Cell wall-defective bacteria which later reverted to acid-fast bacilli have been isolated from sarcoid tissue. These have not been conclusively shown to be mycobacteria. Specific PCR assays were applied to identify mycobacterial nucleic acids in these cultured isolates and in fresh specimens obtained from patients with sarcoidosis. Positive amplification and hybridization were observed with Mycobacterium avium complex- and/or Mycobacterium paratuberculosis-specific probes in five of the six cultured isolates and two fresh skin biopsy samples and one cerebrospinal fluid specimen. There was no amplification or hybridization with Mycobacterium tuberculosis or M. avium subsp. silvaticum probes, respectively. Patients' sera were also tested for antibody reactivities by immunoblotting with M. paratuberculosis recombinant clones expressing the 36,000-molecular-weight antigen (36K antigen) (p36) and the 65K heat shock protein (PTB65K). All seven sarcoidosis, four of six tuberculosis, and all six leprosy patient serum specimens showed strong reactivity with p36 antigen. In contrast, 13 of 38 controls showed only weak reactivity with p36 (P = 0.002 for controls versus sarcoidosis samples). Similarly, PTB65K reacted with high intensity with sera from 5 of 5 sarcoidosis, 5 of 6 tuberculosis, and 5 of 6 leprosy patients, compared with its low-intensity reaction with 5 of 22 controls (P = 0.001 for controls versus sarcoidosis samples). This study demonstrates the isolation and/or identification of M. paratuberculosis or a closely related M. avium complex strain from sarcoid skin lesions and cerebrospinal fluid. Furthermore, the reactivity of antibodies in sarcoid patient sera against p36 and PTB65K antigens was comparable to the reactivity of sera obtained from patients with known mycobacterial disease. Collectively, these data provide further support for the theory of the mycobacterial etiology of sarcoidosis.

Paratuberculosis: a potential zoonosis?

Available literature on the controversial role of Mycobacterium paratuberculosis as an etiologic agent in human Crohn's disease is reviewed. Despite almost 15 years of investigation, the question of causal or consequential association between Johne's disease and Crohn's disease continues to linger.

Johne's disease eradication and control: regulatory implications

The time has come for the livestock industry and the veterinary profession to take Johne's disease seriously in the United States. The continued spread of the disease with accompanying economic hardship to infected herds and the possibility that M. paratuberculosis may be a food-borne pathogen makes inaction a costly proposition. Efforts have started at the national level with NJWG to have guidelines written for a national control program for Johne's disease. A national control program is desirable because it would provide uniformity to control efforts. Veterinarians and livestock owners should be aware of the effort and let their views be known. In addition, national program guidelines already have been written (see the appendix) to certify test-negative herds for paratuberculosis. States that do not offer the certification program should consider it. A list of test-negative herds for Johne's disease that livestock owners could use to buy low risk animals would be a significant step forward in our efforts to control Johne's disease. Federal regulations concerning Johne's disease are outdated and should be changed to facilitate participation by the livestock industry in a Johne's disease control and eradication program.

An abattoir-based study of the prevalence of subclinical Johne's disease in adult cattle in south west England

The prevalance of subclinical Johne's disease was estimated in adult cattle slaughtered at three major abattoirs in south west England. A polymerase chain reaction (PCR) based on IS900 was used to detect Mycobacterium paratuberculosis in intestinal lymph nodes of 1553 cattle. Culture was also carried out on all PCR positive and inconclusive samples. The prevalence of subclinical disease in adult cattle was 3.5% (95% confidence intervals (CI) 2.6-4.7) by PCR and 2.6% (CI 1.8-3.6) by culture. The proportion of the disease in each month ranged from 1.6% (CI 0.2-5.5) in April to 4.6% (CI 2.8-6.9) in November, but the difference was not significant (P > 0.05). The proportion of PCR positive lymph nodes in each abattoir ranged from 2.8% (CI 1.6-4.6) to 4.9% (CI 2.9-7.6), this difference was not significant either (P > 0.05). The prevalence in young cattle was 2.0% (CI 0.6-4.5). The difference between age groups was not statistically significant (P > 0.05).

Cytokines and gastrointestinal disease mechanisms

Cytokines mediate immune responses and are detectable in the normal gastrointestinal mucosa. It is unclear how cytokines are physiologically regulated but in inflammatory enteropathies their expression is often greatly increased and may account for the tissue damage observed. T-cells may be sub-divided according to the pattern of cytokines which they secrete. TH1 cytokine expression is increased in delayed type IV cell mediate immune responses whereas TH2 cytokines are raised in diseases in which humoral mechanisms are more important. Cytokines are secreted by macrophages in relatively greater amounts than from T-cells. They are non-specific products of inflammation and may account for the majority of tissue damage seen in mucosal disease. The pattern of cytokine secretion may determine the immunopathogenesis of an inflammatory disorder. The ultimate goal of cytokine research is the development of therapeutic measures based on a better understanding of their actions which may be achieved with a better understanding of the molecular immune-microenvironment in inflammatory enteropathies. Studies with transgenic mice and gene targeted mice have important implications to the understanding of the immune system and its role in intestinal diseases.