Detection and Isolation of Mycobacterium avium subspecies paratuberculosis from intestinal mucosal biopsies of patients with and without Crohn's disease in Sardinia

Detection of serum antibodies cross-reacting with Mycobacterium avium subspecies paratuberculosis and beta-cell antigen zinc transporter 8 homologous peptides in patients with high-risk proliferative diabetic retinopathy

Purpose

MAP3865c, a Mycobacterium avium subspecies paratuberculosis (MAP) cell membrane protein, has a relevant sequence homology with zinc transporter 8 (ZnT8), a beta-cell membrane protein involved in Zn++ transportation. Recently, antibodies recognizing MAP3865c epitopes have been shown to cross-react with ZnT8 in type 1 diabetes patients. The purpose of this study was to detect antibodies against MAP3865c peptides in patients with high-risk proliferative diabetic retinopathy and speculate on whether they may somehow be involved in the pathogenesis of this severe retinal disorder.

Methods

Blood samples were obtained from 62 type 1 and 80 type 2 diabetes patients with high-risk proliferative diabetic retinopathy and 81 healthy controls. Antibodies against 6 highly immunogenic MAP3865c peptides were detected by indirect ELISA.

Results

Type 1 diabetes patients had significantly higher rates of positive antibodies than controls. Conversely, no statistically significant differences were found between type 2 diabetes patients and controls. After categorization of type 1 diabetes patients into two groups, one with positive, the other with negative antibodies, we found that they had similar mean visual acuity (∼0.6) and identical rates of vitreous hemorrhage (28.6%). Conversely, Hashimoto's thyroiditis prevalence was 4/13 (30.7%) in the positive antibody group and 1/49 (2%) in the negative antibody group, a statistically significant difference (P = 0.016).

Conclusions

This study confirmed that type 1 diabetes patients have significantly higher rates of positive antibodies against MAP/ZnT8 peptides, but failed to find a correlation between the presence of these antibodies and the severity degree of high-risk proliferative diabetic retinopathy. The significantly higher prevalence of Hashimoto's disease among type 1 diabetes patients with positive antibodies might suggest a possible common environmental trigger for these conditions.

Infectious etiopathogenesis of Crohn’s disease

Important advances during the last decade have been made in understanding the complex etiopathogenesis of Crohn’s disease (CD). While many gaps in our knowledge still exist, it has been suggested that the etiology of CD is multifactorial including genetic, environmental and infectious factors. The most widely accepted theory states that CD is caused by an aggressive immune response to infectious agents in genetically predisposed individuals. The rise of genome-wide association studies allowed the identification of loci and genetic variants in several components of host innate and adaptive immune responses to microorganisms in the gut, highlighting an implication of intestinal microbiota in CD etiology. Moreover, numerous independent studies reported a dysbiosis, i.e., a modification of intestinal microbiota composition, with an imbalance between the abundance of beneficial and harmful bacteria. Although microorganisms including viruses, yeasts, fungi and bacteria have been postulated as potential CD pathogens, based on epidemiological, clinicopathological, genetic and experimental evidence, their precise role in this disease is not clearly defined. This review summarizes the current knowledge of the infectious agents associated with an increased risk of developing CD. Therapeutic approaches to modulate the intestinal dysbiosis and to target the putative CD-associated pathogens, as well as their potential mechanisms of action are also discussed.

Recognition of zinc transporter 8 and MAP3865c homologous epitopes by new-onset type 1 diabetes children from continental Italy

There are several pieces of evidence indicating that Mycobacterium avium subspecies paratuberculosis (MAP) infection is linked to type 1 diabetes (T1D) in Sardinian patients. An association between MAP and T1D was recently observed in an Italian cohort of pediatric T1D individuals, characterized by a different genetic background. It is interesting to confirm the prevalence of anti-MAP antibodies (Abs) in another pediatric population from continental Italy, looking at several markers of MAP presence. New-onset T1D children, compared to age-matched healthy controls (HCs), were tested by indirect enzyme-linked immunosorbent assay for the presence of Abs toward the immunodominant MAP3865c/ZnT8 homologues epitopes, the recently identified C-terminal MAP3865c281-287 epitope and MAP-specific protein MptD. Abs against MAP and ZnT8 epitopes were more prevalent in the sera of new-onset T1D children compared to HCs. These findings support the view that MAP3865c/ZnT8 cross-reactivity is involved in the pathogenesis of T1D, and addition of Abs against these peptides to the panel of existing T1D biomarkers should be considered. It is important now to investigate the timing of MAP infection during prospective follow-up in at-risk children to elucidate whether Ab-titers against these MAP/ZnT8 epitopes are present before T1D onset and if so if they wane after diagnosis.

Mycobacterium avium Subspecies paratuberculosis: Human Exposure through Environmental and Domestic Aerosols

Mycobacterium avium subspecies paratuberculosis (Map) causes Johne's disease in animals and is significantly associated with Crohn's disease (CD) in humans. Our previous studies have shown Map to be present in U.K. rivers due to land deposition from chronic livestock infection and runoff driven by rainfall. The epidemiology of CD in Cardiff showed a significant association with the River Taff, in which Map can be detected on a regular basis. We have previously hypothesized that aerosols from the river might influence the epidemiology of CD. In this preliminary study, we detected Map by quantitative PCR in one of five aerosol samples collected above the River Taff. In addition, we examined domestic showers from different regions in the U.K. and detected Map in three out of 30 independent samples. In detecting Map in river aerosols and those from domestic showers, this is the first study to provide evidence that aerosols are an exposure route for Map to humans and may play a role in the epidemiology of CD.

Mycobacterium avium subspecies paratuberculosis causes Crohn's disease in some inflammatory bowel disease patients

Crohn’s disease (CD) is a chronic inflammatory condition that plagues millions all over the world. This debilitating bowel disease can start in early childhood and continue into late adulthood. Signs and symptoms are usually many and multiple tests are often required for the diagnosis and confirmation of this disease. However, little is still understood about the cause(s) of CD. As a result, several theories have been proposed over the years. One theory in particular is that Mycobacterium avium subspecies paratuberculosis (MAP) is intimately linked to the etiology of CD. This fastidious bacterium also known to cause Johne’s disease in cattle has infected the intestines of animals for years. It is believed that due to the thick, waxy cell wall of MAP it is able to survive the process of pasteurization as well as chemical processes seen in irrigation purification systems. Subsequently meat, dairy products and water serve as key vehicles in the transmission of MAP infection to humans (from farm to fork) who have a genetic predisposition, thus leading to the development of CD. The challenges faced in culturing this bacterium from CD are many. Examples include its extreme slow growth, lack of cell wall, low abundance, and its mycobactin dependency. In this review article, data from 60 studies showing the detection and isolation of MAP by PCR and culture techniques have been reviewed. Although this review may not be 100% comprehensive of all studies, clearly the majority of the studies overwhelmingly and definitively support the role of MAP in at least 30%-50% of CD patients. It is very possible that lack of detection of MAP from some CD patients may be due to the absence of MAP role in these patients. The latter statement is conditional on utilization of methodology appropriate for detection of human MAP strains. Ultimately, stratification of CD and inflammatory bowel disease patients for the presence or absence of MAP is necessary for appropriate and effective treatment which may lead to a cure.

Recognition of zinc transporter 8 and MAP3865c homologous epitopes by Hashimoto's thyroiditis subjects from Sardinia: a common target with type 1 diabetes?

Mycobacterium avium subspecies paratuberculosis (MAP) asymptomatic infection has been previously linked to Type 1 diabetes (T1D) and Multiple Sclerosis. An association between MAP infection and Hashimoto's thyroiditis (HT) was also proposed only in a case report. This study aimed to investigate the robustness of the latter association, testing a large cohort of HT and healthy control (HCs) subjects, all from Sardinia. Prevalence of anti-MAP3865c Abs was assessed by indirect enzyme-linked immunosorbent assay (ELISA). Moreover, given that human ZnT8 is specifically expressed in the pancreatic β-cells, in the follicle epithelial cells and in the parafollicular cells of the thyroid gland, we also tested ZnT8 epitopes homologues to the MAP3865c immunodominant peptides previously identified. Indeed, Abs targeting MAP3865c and ZnT8 homologous regions display similar frequencies in patients and controls, thus suggesting that Abs recognizing these epitopes could be cross-reactive. A statistically significant difference was found between HT patients and HCs when analyzing the humoral response mounted against MAP3865c/ZnT8 homologues epitopes. To our knowledge, this is the first report, which provides statistically significant evidence sustaining the existence of an association between MAP sero-reactivity and HT. Further studies are required to investigate the relevance of MAP to HT, aimed at deciphering if this pathogen can be at play in triggering this autoimmune disease. Likewise, genetic polymorphism of the host, and other environmental factors need to be investigated.

Genome-wide association analysis and genomic prediction of Mycobacterium avium subspecies paratuberculosis infection in US Jersey cattle

Paratuberculosis (Johne’s disease), an enteric disorder in ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP), causes economic losses in excess of $200 million annually to the US dairy industry. To identify genomic regions underlying susceptibility to MAP infection in Jersey cattle, a case-control genome-wide association study (GWAS) was performed. Blood and fecal samples were collected from ∼5,000 mature cows in 30 commercial Jersey herds from across the US. Discovery data consisted of 450 cases and 439 controls genotyped with the Illumina BovineSNP50 BeadChip. Cases were animals with positive ELISA and fecal culture (FC) results. Controls were animals negative to both ELISA and FC tests that matched cases on birth date and herd. Validation data consisted of 180 animals including 90 cases (positive to FC) and 90 controls (negative to ELISA and FC), selected from discovery herds and genotyped by Illumina BovineLD BeadChip (∼7K SNPs). Two analytical approaches were used: single-marker GWAS using the GRAMMAR-GC method and Bayesian variable selection (Bayes C) using GenSel software. GRAMMAR-GC identified one SNP on BTA7 at 68 megabases (Mb) surpassing a significance threshold of 5×10⁻⁵. ARS-BFGL-NGS-11887 on BTA23 (27.7 Mb) accounted for the highest percentage of genetic variance (3.3%) in the Bayes C analysis. SNPs identified in common by GRAMMAR-GC and Bayes C in both discovery and combined data were mapped to BTA23 (27, 29 and 44 Mb), 3 (100, 101, 106 and 107 Mb) and 17 (57 Mb). Correspondence between results of GRAMMAR-GC and Bayes C was high (70–80% of most significant SNPs in common). These SNPs could potentially be associated with causal variants underlying susceptibility to MAP infection in Jersey cattle. Predictive performance of the model developed by Bayes C for prediction of infection status of animals in validation set was low (55% probability of correct ranking of paired case and control samples).

Role of the gut microbiota in inflammatory bowel disease pathogenesis: What have we learnt in the past 10 years?

Our understanding of the microbial involvement in inflammatory bowel disease (IBD) pathogenesis has increased exponentially over the past decade. The development of newer molecular tools for the global assessment of the gut microbiome and the identification of nucleotide-binding oligomerization domain-containing protein 2 in 2001 and other susceptibility genes for Crohn’s disease in particular has led to better understanding of the aetiopathogenesis of IBD. The microbial studies have elaborated the normal composition of the gut microbiome and its perturbations in the setting of IBD. This altered microbiome or “dysbiosis” is a key player in the protracted course of inflammation in IBD. Numerous genome-wide association studies have identified further genes involved in gastrointestinal innate immunity (including polymorphisms in genes involved in autophagy: ATG16L1 and IGRM), which have helped elucidate the relationship of the local innate immunity with the adjacent luminal bacteria. These developments have also spurred the search for specific pathogens which may have a role in the metamorphosis of the gut microbiome from a symbiotic entity to a putative pathogenic one. Here we review advances in our understanding of microbial involvement in IBD pathogenesis over the past 10 years and offer insight into how this will shape our therapeutic management of the disease in the coming years.

Effect of inflammatory bowel disease therapies on immunogenicity of Mycobacterium paratuberculosis proteins

BACKGROUND AND AIMS

The link between Mycobacterium avium subsp. paratuberculosis (MAP) and Crohn's disease (CD) is supported by several studies that have reported the detection and isolation of MAP from human tissues, but causation has not yet been proven. Preliminary studies have shown higher levels of antibodies in sera from CD patients against secreted protein from MAP within human macrophages when compared to healthy controls. The immunogenicity of this protein in CD patients under different treatment regimes was evaluated.

MATERIALS AND METHODS

Sera of 110 CD patients, 82 ulcerative colitis (UC), and 150 healthy controls were collected and the presence of antibodies against the mycobacterial protein tyrosine phosphatase PtpA was assayed using ELISA.

RESULTS

A statistically significant difference in the level of antibodies against PtpA was measured in untreated CD patients versus healthy controls, but variation in the antibody levels was observed when patients were subjected to different treatment regimens. UC patients showed no differences in the levels of antibodies against PtpA when compared to healthy controls.

CONCLUSIONS

CD patients under different drug treatments show a clear difference in the levels of antibodies against a protein secreted by MAP, suggesting that if MAP is active in the progress of CD, some treatments can be detrimental to its survival.

Crohn's disease-specific pancreatic autoantibodies are specifically present in ruminants with paratuberculosis: implications for the pathogenesis of the human disease

Mycobacterium avium subspecies paratuberculosis (MAP) induces paratuberculosis (ptb) in ruminants and has clinical and histological features resebling Crohn's disease (CD). Pancreatic autoantibodies (PAB) targeting glycoprotein 2 (GP2) are specifically found in CD, but it is currently unknown whether these autoantibodies can be found in ruminants with ptb. IgG anti-MAP and anti-GP2 antibodies were tested by ELISA in 286 ruminants (212 sheep and 74 cattle). PAB testing was performed by indirect immunofluorescence (IIF) using anti-sheep or anti-cattle specific antisera. PCR analysis confirmed the presence of MAP in anti-MAP positive samples. Anti-GP2 antibodies were more prevalent in anti-MAP antibody positive (26.9%) than in anti-MAP negative ruminants (8.7%, p < 0.001). Anti-GP2 antibodies were found in 16/70 (22.9%) anti-MAP positive sheep compared to 10/142 (7%, p = 0.001) anti-MAP antibody negative and in anti-MAP positive cattle than in negative counterparts (5/8 versus 8/66, p = 0.003). Absorbance values for anti-GP2 antibodies were higher in cattle than in sheep (mean 21 AU/mL ± 25.4SD versus 12.2 AU/mL ± 23 SD, p < 0.001). There was no correlation between anti-GP2 and anti-MAP antibody concentrations. Anti-GP2 antibodies persisted up to 1/1000 and showed the characteristic IIF pancreatic pattern seen by anti-GP2 antibody positive CD samples. This is the first study to demonstrate the presence of CD-specific GP2-reactive pancreatic autoantibodies in MAP-infected ruminants. Our data suggest that CD and ptb are characterised by an antigen-driven loss of immunological tolerance to GP2, implying commonalities in the immunopathogenesis of the human and ruminant inflammatory bowel disorder.

M. paratuberculosis Heat Shock Protein 65 and Human Diseases: Bridging Infection and Autoimmunity

Mycobacterium avium subspecies paratuberculosis (MAP) is the known infectious cause of Johne's disease, an enteric inflammatory disease mostly studied in ruminant animals. MAP has also been implicated in the very similar Crohn's disease of humans as well as sarcoidosis. Recently, MAP has been associated with juvenile sarcoidosis (Blau syndrome), autoimmune diabetes, autoimmune thyroiditis, and multiple sclerosis. While it is intuitive to implicate MAP in granulomatous diseases where the microbe participates in the granuloma, it is more difficult to assign a role for MAP in diseases where autoantibodies are a primary feature. MAP may trigger autoimmune antibodies via its heat shock proteins. Mycobacterial heat shock protein 65 (HSP65) is an immunodominant protein that shares sequential and conformational elements with several human host proteins. This molecular mimicry is the proposed etiopathology by which MAP stimulates autoantibodies associated with autoimmune (type 1) diabetes, autoimmune (Hashimoto's) thyroiditis, and multiple sclerosis. This paper proposes that MAP is a source of mycobacterial HSP65 and acts as a trigger of autoimmune disease.

In vitro cytokine profiles and viability of different human cells treated with whole cell lysate of Mycobacterium avium subsp. paratuberculosis

Mycobacterium avium subsp. paratuberculosis (MAP) is a zoonotic pathogen, a very slow growing bacterium which is difficult to isolate and passage in conventional laboratory culture. Although its association with Johne's disease or paratuberculosis of cattle is well established, it has been only putatively linked to Crohn's disease in humans. Further, MAP has been recently suggested to be a trigger for other autoimmune diseases such as type-1 diabetes mellitus (T1DM). Recently, some studies have indicated that exposure to MAP is associated with elevated levels of antibodies against MAP lysate although the exact mechanism and significance of the same remains unclear. Further, the cytokine profiles relevant in MAP associated diseases of humans and their exact role in the pathophysiology are not clearly known. We performed in vitro cytokine analyses after exposing different cultured human cells to the whole cell lysate of MAP and found that MAP lysate induces secretion of cytokines IL-1β, IL-6, IL-8, IL-10 and TNF-α by human peripheral blood mononuclear cells (PBMCs). Also, it induces secretion of IL-8 by cultured human stomach adenocarcinoma cells (AGS) and PANC-1(human pancreatic carcinoma cell line) cells. We also found that MAP lysate induced cytotoxicity in PANC-1cells. Collectively, these results provide a much needed base-line data set of cytokines broadly signifying a MAP induced cellular response by human cells.

Mycobacterium avium ss paratuberculosis-associated diseases: piecing the Crohn's puzzle together

The relation of Mycobacterium avium ss paratuberculosis (MAP) to Crohn's Disease (CD) and other MAP-associated conditions remains controversial. New data, coupled with the analogous Helicobacter pylori (H. pylori) story, has permitted us to piece together the MAP puzzle and move forward with a more scientific way of treating inflammatory bowel disease, particularly CD. As infection moves centre stage in inflammatory bowel disease, the dated "aberrant reaction" etiology has lost scientific credibility. Now, our growing understanding of MAP-associated diseases demands review and articulation. We focus here on (1) the concept of MAP-associated diseases; (2) causality, Johne Disease, the "aberrant reaction" hypothesis; and (3) responses to published misconceptions questioning MAP as a pathogen in CD.

Mycobacterium avium subsp. paratuberculosis in an Italian cohort of type 1 diabetes pediatric patients

Mycobacterium avium subsp. paratuberculosis (MAP) is the etiological agent of Johne's disease in ruminants. Recent studies have linked MAP to type 1 diabetes (T1D) in the Sardinian population. The aim of this study was to investigate the prevalence of MAP infection in a T1D cohort from continental Italy compared with healthy control subjects. 247 T1D subjects and 110 healthy controls were tested for the presence of MAP. MAP DNA was detected using IS900-specific polymerase chain reaction (PCR). The presence of antibodies towards a MAP antigen, heparin binding hemoagglutinin (HBHA), was detected by ELISA. We demonstrated a higher MAP DNA prevalence in plasma samples from T1D patients and a stronger immune response towards MAP HBHA, compared with healthy control subjects. Moreover, in the recent onset patients, we observed an association between anti-MAP antibodies and HLA DQ2 (DQA1 0201/DQB1 0202). These findings taken together support the hypothesis of MAP as an environmental risk factor for the development of T1D in genetically predisposed subjects, probably involving a mechanism of molecular mimicry between MAP antigens and pancreatic islet β-cells.

Mycobacterium avium subsp. paratuberculosis in an Italian cohort of type 1 diabetes pediatric patients

Mycobacterium avium subsp. paratuberculosis (MAP) is the etiological agent of Johne's disease in ruminants. Recent studies have linked MAP to type 1 diabetes (T1D) in the Sardinian population. The aim of this study was to investigate the prevalence of MAP infection in a T1D cohort from continental Italy compared with healthy control subjects. 247 T1D subjects and 110 healthy controls were tested for the presence of MAP. MAP DNA was detected using IS900-specific polymerase chain reaction (PCR). The presence of antibodies towards a MAP antigen, heparin binding hemoagglutinin (HBHA), was detected by ELISA. We demonstrated a higher MAP DNA prevalence in plasma samples from T1D patients and a stronger immune response towards MAP HBHA, compared with healthy control subjects. Moreover, in the recent onset patients, we observed an association between anti-MAP antibodies and HLA DQ2 (DQA1 0201/DQB1 0202). These findings taken together support the hypothesis of MAP as an environmental risk factor for the development of T1D in genetically predisposed subjects, probably involving a mechanism of molecular mimicry between MAP antigens and pancreatic islet β-cells.

Lactase persistence, NOD2 status and Mycobacterium avium subsp. paratuberculosis infection associations to Inflammatory Bowel Disease

Background

Inflammatory Bowel Disease (IBD), which includes both Crohn’s disease (CD) and ulcerative colitis (UC), is caused by a complex interplay involving genetic predisposition, environmental factors and an infectious agent. Mycobacterium avium subsp. paratuberculosis (MAP) is a promising pathogen candidate since it produces a chronic intestinal inflammatory disease in ruminants that resembles CD in humans. MAP is a ubiquitous microorganism, although its presence in the food chain, especially in milk from infected animals, is what made us think that there could be an association between lactase persistence (LP) and IBD. The LCT mutation has brought adaptation to dairy farming which in turn would have increased exposure of the population to infection by MAP. NOD2 gene mutations are highly associated to CD.

Methods

In our study, CD and UC patients and controls from the North of Spain were genotyped for the lactase gene (LCT) and for three NOD-2 variants, R702W, G908R and Cins1007fs. MAP PCR was carried out in order to assess MAP infection status and these results were correlated with LCT and NOD2 genotypes.

Results

As for LP, no association was found with IBD, although UC patients were less likely to present the T/T₋₁₃₉₁₀ variant compared to controls, showing a higher C-allele frequency and a tendency to lactase non-persistence (LNP). NOD2 mutations were associated to CD being the per-allele risk higher for the Cins1007fs variant. MAP infection was more extended among the healthy controls (45.2%) compared to CD patients (21.38%) and UC patients (19.04%) and this was attributed to therapy. The Asturian CD cohort presented higher levels of MAP prevalence (38.6%) compared to the Basque CD cohort (15.5%), differences also attributed to therapy. No interaction was found between MAP infection and LCT or NOD2 status.

Conclusions

We conclude that LP is not significantly associated with IBD, but that MAP infection and NOD2 do show not mutually interacting associations with IBD.

Recent research on bovine paratuberculosis in South Korea

Bovine paratuberculosis (Johne's disease), a chronic and debilitating disease of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP), is a major cause of chronic ruminant enteritis. A national eradication program has been in place in South Korea since the first report of the disease in 1967; however, only limited data on bovine paratuberculosis in South Korea are available. Some research, such as investigations of the reactivity of animal sera against MAP antigens, has been done in localized areas and in limited animal species. Compared with the worldwide situation, the development of diagnostic methods in South Korea has shown similar results even though some data were obtained from international collaborative studies. MAP is considered by some to be zoonotic, noting an association with Crohn's disease, although this issue is still controversial; however, research into this association is limited. Decisions based on disease priorities have hampered active progress in research on the disease. In this paper, we reviewed the available results generated from South Korea compared with global research. Finally, we propose a theme for future research.

Gene expression profiling of Mycobacterium avium subsp. paratuberculosis in simulated multi-stress conditions and within THP-1 cells reveals a new kind of interactive intramacrophage behaviour

BACKGROUND

Recent studies have identified in Mycobacterium avium subsp. paratuberculosis (MAP), already known as a pathogen in ruminants, a potential zoonotic agent of some autoimmune diseases in humans. Therefore, considering the possible risk for public health, it is necessary a thorough understanding of MAP's gene expression during infection of human host as well as the identification of its immunogenic and/or virulence factors for the development of appropriate diagnostic and therapeutic tools.

RESULTS

In order to characterize MAP's transcriptome during macrophage infection, we analyzed for the first time the whole gene expression of a human derived strain of MAP in simulated intraphagosomal conditions and after intracellular infection of the human macrophage cell line THP-1 by using the DNA-microarray technology. Results showed that MAP shifts its transcriptome to an adaptive metabolism for an anoxic environment and nutrient starvation. It up-regulates several response factors to oxidative stress or intracellular conditions and allows, in terms of transcription, a passive surface peptidoglycan spoliation within the macrophage along with an intensification of the anabolic activity for lipidic membrane structures.

CONCLUSIONS

These results indicate a possible interactive system between MAP and its host cell based on the internal mimicry unlike other intracellular pathogens, bringing new hypothesis in the virulence and pathogenicity of MAP and its importance in human health.

Crohn's disease and the mycobacterioses: a quarter century later. Causation or simple association?

It has been more than 25 years since Mycobacterium paratuberculosis was first proposed as an etiologic agent in Crohn's disease based on the isolation of this organism from several patients. Since that time, a great deal of information has been accumulated that clearly establishes an association between M. paratuberculosis and Crohn's disease. However, data are conflicting and difficult to interpret and the field has become divided into committed advocates and confirmed skeptics. This review is an attempt to provide a thorough and objective summary of current knowledge from both basic and clinical research from the views and interpretations of both the antagonists and proponents. The reader is left to draw his or her own conclusions related to the validity of the issues and claims made by the opposing views and data interpretations. Whether M. paratuberculosis is a causative agent in some cases or simply represents an incidental association remains a controversial topic, but current evidence suggests that the notion should not be so readily dismissed. Remaining questions that need to be addressed in defining the role of M. paratuberculosis in Crohn's disease and future implications are discussed.

Molecular pathogenesis of bovine paratuberculosis and human inflammatory bowel diseases

Paratuberculosis (Ptb), caused by Mycobacterium avium subsp. paratuberculosis (Map), is a chronic enteritis that affects many ruminants and other wild animals worldwide. Ptb is a great concern in animal health and in etiology of human Crohn's disease (CD). In the present study, we detected Map-specific insertion sequence IS900 of DNA in tissue sections surgically removed from lesions of patients with CD (29 samples), ulcerative colitis (UC) (17 samples), and non-inflammatory bowel disease (IBD) (20 samples). We then compared the histopathological findings of 29 CD and 17 UC cases with those of 35 cases of bovine Ptb, since few comparative pathological studies of human IBD and Ptb have been conducted. The QPCR examination indicated positive results in 13.37% of CD cases, 3.57% of UC cases, and 10% of non-IBD cases. Human CD tissues typically exhibited destructive full thickness enteritis with severe lympho-plasma infiltration and scattered additional granulomas; UC lesions exhibited much less inflammation than CD lesions. Non-IBD control samples did not exhibit pathological changes. Human CD and UC lesions were very different from Ptb lesions that are characterized by predominant granuloma formation. Immunohistochemistry for Map antigen and acid-fast staining were negative in all human IBD cases but were always positive in Ptb cases. Our present comparative study strongly suggests that we reconsider the previous hypothesis that "Map infection" causes CD, even though human intestines were considered to have been exposed to the Map antigen containing the DNA.

Interaction between Mycobacterium tuberculosis, Mycobacterium bovis, Mycobacterium avium subspecies paratuberculosis with the enteric glia and microglial cells

Background

We investigated the interaction of Mycobacterium avium subspecies paratuberculosis, M. bovis and M. tuberculosis and different glial cells (enteric glial and microglial cells) in order to evaluate the infecting ability of these microorganisms and the effects produced on these cells, such as the evaluation of cytokines expression.

Results

Our experiments demonstrated the adhesion of M. paratuberculosis to the enteroglial cells and the induction of IL-1A and IL-6 expression; M. tuberculosis and M. bovis showed a good adhesive capability to the enteric cell line with the expression of the following cytokines: IL-1A and IL-1B, TNF-α, G-CSF and GM-CSF; M. bovis induced the expression of IL-6 too.

The experiment performed with the microglial cells confirmed the results obtained with the enteroglial cells after the infection with M. tuberculosis and M. bovis, whereas M. paratuberculosis stimulated the production of IL-1A and IL-1B.

Conclusion

Enteroglial and microglial cells, could be the target of pathogenic mycobacteria and, even if present in different locations (Enteric Nervous System and Central Nervous System), show to have similar mechanism of immunomodulation.

Antibodies recognizing Mycobacterium avium paratuberculosis epitopes cross-react with the beta-cell antigen ZnT8 in Sardinian type 1 diabetic patients

The environmental factors at play in the pathogenesis of type 1 diabetes (T1D) remain enigmatic. Mycobacterium avium subspecies paratuberculosis (MAP) is transmitted from dairy herds to humans through food contamination. MAP causes an asymptomatic infection that is highly prevalent in Sardinian T1D patients compared with type 2 diabetes (T2D) and healthy controls. Moreover, MAP elicits humoral responses against several mycobacterial proteins. We asked whether antibodies (Abs) against one of these proteins, namely MAP3865c, which displays a sequence homology with the β-cell protein zinc transporter 8 (ZnT8) could be cross-reactive with ZnT8 epitopes. To this end, Ab responses against MAP3865c were analyzed in Sardinian T1D, T2D and healthy subjects using an enzymatic immunoassay. Abs against MAP3865c recognized two immunodominant transmembrane epitopes in 52-65% of T1D patients, but only in 5-7% of T2D and 3-5% of healthy controls. There was a linear correlation between titers of anti-MAP3865c and anti-ZnT8 Abs targeting these two homologous epitopes, and pre-incubation of sera with ZnT8 epitope peptides blocked binding to the corresponding MAP3865c peptides. These results demonstrate that Abs recognizing MAP3865c epitopes cross-react with ZnT8, possibly underlying a molecular mimicry mechanism, which may precipitate T1D in MAP-infected individuals.

Fecal detection of Mycobacterium avium paratuberculosis using the IS900 DNA sequence in Crohn's disease and ulcerative colitis patients and healthy subjects

BACKGROUND AND AIM

Despite the increasing evidence of MAP/DNA isolation in Crohn's disease (CD), its potential pathogenetic role remains unclear. To further clarify the possible relationship between MAP and CD, we investigated the presence of IS900 DNA fragment in feces from Crohn's disease and ulcerative colitis (UC) patients and from healthy controls (HC).

METHODS

Stool samples were collected from 31 CD, 20 UC, and 23 HC and stored at -20°C in 200-mg aliquots. DNA was extracted. MAP presence was detected with a specific PCR amplifying a 409-bp fragment from IS900. The specificity of PCR for IS900 was confirmed sequencing three positive products. Statistical analysis was performed using the Chi-square test.

RESULTS

Twenty-one of 31 CD (68%), 13 of 20 UC (65%) and 11 of 23 HC (48%) were MAP-positive (CD vs. HC: p = ns; UC vs. HC: p = ns). With the limits of a small sample size, the IS900-positive percentage in CD and UC was higher than HC, although the difference was not statistically significant.

CONCLUSIONS

The possibility to track the MAP presence in human feces represents a new approach to the "MAP hypothesis". Detection of MAP DNA in feces is very common, reaching very high prevalence both in CD and in UC and even in HC. Our findings seem consistent with a high prevalence of MAP asymptomatic infection among the general population and so the possible involvement of MAP in CD pathogenesis could be linked to a specific immune defective response.

Mycobacterium paratuberculosis and autism: is this a trigger?

Autism is a heterogeneous group of life-long neurologic problems that begin in childhood. Success in efforts to understand and treat autism has been mostly elusive. The role of autoimmunity in autism has gained recognition both for associated systemic autoimmune disease and the presence of brain autoantibodies in autistic children and their family members. There is an acknowledged genetic susceptibility to autism--most notably allotypes of complement C4. C4 defects are associated with several autoimmune diseases and also confer susceptibility to mycobacterial infections. Mycobacterium avium ss. paratuberculosis (MAP) causes an enteric inflammatory disease in ruminant animals (Johne's disease) and is the putative cause of the very similar Crohn's disease in humans. Humans are widely exposed to MAP in food and water. MAP has been also linked to ulcerative colitis, irritable bowel syndrome, sarcoidosis, Blau syndrome, autoimmune (Type 1) diabetes, Hashimoto's thyroiditis and multiple sclerosis. Environmental agents are thought to trigger autism in the genetically at risk. Molecular mimicry is the proposed mechanism by which MAP is thought to trigger autoantibodies. Autoantibodies to brain myelin basic protein (MBP) is a common feature of autism. This article considers the subset of autoimmunity-related autism patients and postulates that MAP, through molecular mimicry to its heat shock protein HSP65, triggers autism by stimulating antibodies that cross react with myelin basic protein (MBP).

Ovine paratuberculosis: a seroprevalence study in dairy flocks reared in the marche region, Italy

In order to fulfil the seroprevalence gap on Mycobacterium avium subsp. paratuberculosis infection in ovine dairy farms of Marche region (central Italy), a stratified study was carried out on 2086 adult female sheep randomly chosen from 38 herds selected in Ancona and Macerata provinces. 73.7% flocks resulted infected by a commercial ELISA test (Pourquier, France), with a mean seroprevalence of 6.29% of sampled sheep in both provinces. A higher number of MAP seropositive ewes was recorded in the large herds' consistence than in the small and medium herds' consistence (P = 0.0269), and a greater percentage of infected sheep was obtained among female at early/late than in peak lactation stage (P = 0.0237). MAP infection was confirmed in 12.6% of infected farms by faecal culture. The true sheep-level seroprevalence was 15.1% ± 7.3%.

Mycobacterium avium subspecies Paratuberculosis and Crohn's regional ileitis: how strong is association?

Mycobacterium avium subsp. paratuberculosis (MAP) is a well-established etiological agent of Johne's disease in animals. In humans, similar clinical condition, first described by Crohn as regional ileitis in 1932, now known as Crohn's diseases (CD), has also been associated with this mycobacterial species. However, there are two schools of thoughts, one favoring MAP as its etiological agent while the second considers it as an immune-inflammatory condition triggered by an external factor. Onset of CD requires a series of events including predisposition of certain inherited genetic traits, associated environmental stimuli, and immune-inflammatory response. A combination of these factors probably leads to this disease. Recently, some human genes have also been identified which regulate ability to respond appropriately to the external factors. Added to these factors are concerns about the selection of clinical specimens and poor adherence to laboratory quality controls. The literature is full of contradictory findings, but there a lack of uniformity in the materials and methods used by many of these researchers. In this review, we provide our perspective under above circumstances and give our point of view which may open a platform for debate regarding the MAP as the etiological agent of human CD.

High prevalence of Mycobacterium avium subspecies paratuberculosis ('Indian bison type') in animal attendants suffering from gastrointestinal complaints who work with goat herds endemic for Johne's disease in India

OBJECTIVES

In this study we aimed to estimate the prevalence of Mycobacterium avium subspecies paratuberculosis (MAP) in animal attendants who were chronic colitis patients or who had inflammatory bowel disease and were suspected for Crohn's disease; these animal attendants worked with goat herds endemic for Johne's disease. Microscopic examination and culture tests were used. For comparison purposes a group of healthy human subjects (not suffering with colitis) was also screened.

METHODS

Stool samples obtained from 98 human subjects (58 animal attendants suspected for Crohn's disease and 40 healthy humans) were screened for the presence of MAP by microscopic examination and culture. Of the 58 animal attendants screened, 38 had abdominal pain, 29 had suffered episodes of diarrhea, 39 had experienced weight loss, 27 had fever, and 32 had a history of raw milk consumption. Animal attendants had had contact of variable duration with goat herds endemic for Johne's disease (1-5, 6-10, 11-15, and >15 years). Forty stool samples from healthy humans with no symptoms/history of contact with animals were also screened. IS900 PCR and IS1311 PCR restriction endonuclease analysis were used to characterize and genotype the MAP colonies.

RESULTS

MAP was recovered from 34 of the 98 human subject stool samples (34.7%). Of the 98 samples, 16.3% (n=16) were acid-fast. None of the 40 healthy human subjects were positive for MAP by microscopy, but five (12.5%) were positive for MAP by culture. Of the 58 animal attendants, 16 (27.6%) were positive by microscopy and 29 (50%) were positive by culture. MAP were recovered from 68.4% of animal attendants with abdominal pain, 72.4% of those with diarrhea, 71.8% of those with weight loss, 44.4% of those with fever, and 46.9% of those who had a history of raw milk consumption. Of the 29 culture-positive animal attendants, 48.3% had worked for >15 years, 27.6% for 11-15 years, 20.7% for 6-10 years, and 3.4% for 1-5 years with goat herds endemic for Johne's disease. Of the 34 culture isolates, 28 (82.4%) showed good quality DNA on agarose gel and were positive by IS900 PCR. Of the 28 IS900-positive DNA samples, 23 (82.1%) were genotyped as 'Indian bison type' and five (17.9%) as 'cattle type'.

CONCLUSIONS

The prevalence of MAP was higher in attendants suffering from gastrointestinal problems who worked with goat herds endemic for Johne's disease, than in humans with no history of contact with animals. The risk of developing gastrointestinal problems with clinical symptoms indistinguishable from inflammatory bowel disease was higher in humans who were in contact with goat herds endemic for Johne's disease as compared to healthy humans, and the risk was correlated with the duration of association with the endemic goat herds.

Evaluation of "Indigenous Absorbed ELISA Kit" for the Estimation of Seroprevalence of Mycobacterium avium Subspecies paratuberculosis Antibodies in Human Beings in North India

In present pilot study aimed to estimate, presence of Mycobacterium avium subspecies paratuberculosis (MAP) antibodies in the human serum samples originating from North India using "Indigenous absorbed ELISA kit" (ELISA kit). The phase I, "ELISA kit" was optimized using protoplasmic antigen from native isolate of MAP "Indian Bison type" recovered from the biopsies of Crohn's disease patients. The phase II, sensitivity and specificity of the kit were estimated as 40.0 and 83.3%, respectively, when evaluated in 40 human serum samples (5 Crohn's disease and 22 ulcerative colitis patients and 13 healthy human subjects) with defined MAP status with respect to stool culture. Seroprevalence of MAP antibodies was higher in CD patients (80.0%) as compared to ulcerative colitis patients (4.5%) and normal human subjects (15.3%). The phase III, seroprevalence of MAP antibodies was estimated as 23.4%, on the basis of the screening of 452 human serum samples (without history) from different geographical regions of North India. Region-wise, 34.0, 33.3, 32.8, 25.0, 23.0, 17.7, and 12.5% samples were positive from the states of Punjab, Uttarakhand, New Delhi, Himachal Pradesh, Haryana, Uttar Pradesh and Jammu and Kashmir, respectively. Study reported moderately higher presence of MAP antibodies in human population, which necessitates programs to reduce the bioburden of MAP in the environment and in animal population.

MAP3738c and MptD are specific tags of Mycobacterium avium subsp. paratuberculosis infection in type I diabetes mellitus

Mycobacterium avium subsp. paratuberculosis (Map) is the causative agent of Johne's disease, a chronic inflammation of ruminants' intestine. Recent studies have linked Map to type I Diabetes mellitus (T1DM). We searched the presence of antibodies against two specific proteins of Map (MptD and MAP3738c) in sera of patients affected by T1DM and type II Diabetes mellitus (T2DM). MptD protein (MAP3733c) has been recognized as a Map virulent factor whereas MAP3738c has not yet been studied. Both proteins are encoded by genes belonging to a Map specific pathogenicity island. Forty three T1DM patients' sera, 56 T2DM patients' sera and 48 healthy subjects' sera were screened by ELISA to evaluate the immunoresponse against MptD or MAP3738c recombinant proteins. Results showed a positive response to both proteins in T1DM patients whereas no difference with controls was found for T2DM patients. Results suggest a potential relation between T1DM and the bacterial infection.

Association of Mycobacterium avium subsp. paratuberculosis with multiple sclerosis in Sardinian patients

Mycobacterium avium subsp. paratuberculosis (MAP) infection is highly spread in the ruminant herds of Sardinia, in the Western Mediterranean. The objective of this study was to investigate prevalence of MAP infection in association with Multiple Sclerosis (MS) using clinical specimen from patients and controls. We analyzed samples for the presence of MAP specific DNA and to demonstrate humoral response to a MAP protein (MAP2694), a predicted homologue of the T-cell receptor gamma-chain/complement component 1 of the host. We found presence of MAP DNA in 42% of the MS patients and an extremely significant humoral immune response revealed by the MS patients against the MAP protein. In our opinion, this is the first report that significantly associates MAP infection with MS. Further studies will be required to confirm if MAP could be one of the triggers of MS, according to the molecular mimicry theory, in susceptible (and genetically at risk) individuals.

Mycobacterium avium subsp. Paratuberculosis and the expression of selected virulence and pathogenesis genes in response to 6°C, 65°c and ph 2.0

The aim of this work was to study the expression of selected Mycobacterium avium subsp. paratuberculosis (MAP) genes connected with MAP virulence, adhesion and stress response. The temperature of 6°C and 65°C were chosen with regard to the food industry, storage conditions (refrigerator) and low-temperature pasteurization. A pH of 2.0, using lactic acid, was selected to mimic the natural environment of the stomach. Expression of selected genes was studied using real time reverse transcription PCR on three different MAP isolates. MAP isolates were chosen according to the number of their preceding cultivations. While isolates 8672 and 8819 were previously cultivated only once, MAP isolate 12146 went through four passages. Different expression profiles were observed in each of the three MAP isolates. However, particular similar patterns were observed. SigE, sigF and ahpC were up-regulated, while sigL was down-regulated under temperature stress. Mmp gene was found to be down-regulated under acidic conditions. Low passage isolates (8672 and 8819) showed certain level of acid resistance.

Mycobacterium avium subsp. paratuberculosis in dairy products, meat, and drinking water

Mycobacterium avium subsp. paratuberculosis (Map) is the cause of Johne's disease, a chronic infection of the gut, in ruminant animals that provide milk and/or meat for human consumption. Map also may be involved in Crohn's disease and type 1 diabetes in humans. Although the role of Map in human diseases has not been established, minimizing the exposure of humans to the organism is considered desirable as a precautionary measure. Infected animals can shed Map in feces and milk, and the organism can become disseminated in tissues remote from the gut and its associated lymph nodes. The presence of at least some Map in raw milk and meat and in natural waters is likely, but the numbers of Map in those foods and waters should be reduced through cooking or purification. The available information relating to Map in milk and dairy products, meats, and drinking water is reviewed here for assessment of the risks of exposure to Map from consumption of such foods and water.

Persistent enteric mycobacterial infection enhances sensitivity to acute mucosal injury

Antigen presenting cells such as intestinal macrophages are dynamic effector cells that play a critical role in maintaining mucosal homeostasis. However, it is not known how occult intestinal infections alter the response of the intestinal mucosa to subsequent intestinal injury. The aim of this study was to evaluate how persistent subclinical intestinal infection with Mycobacterium avium subsp. paratuberculosis ( Map) would influence acute dextran sulfate sodium (DSS)-mediated intestinal inflammation. BALB/c mice were infected intraperitoneally with Map. Following an incubation period of 90 d, mice were administered 2% DSS in the drinking water for six days. Prior to and during treatment with DSS, mice were evaluated for clinical signs of disease and body weights were recorded. At termination of the experiment, body weights, frequency of rectal blood, and gross and histological cecal lesions were evaluated, and tissues were collected for isolation of Map. Subclinical and persistent intestinal Map infection was established based on the absence of both weight loss and rectal blood and the isolation of Map from the small and large intestines in mice infected with Map only. Following treatment with DSS, Map-infected mice had increased weight loss, increased frequency of rectal blood, and exacerbation of gross lesions and increased cecal lesion scores. Also, there was a significant reduction in Map isolated from the small intestines of Map-infected and DSS-treated mice. In conclusion, subclinical Map infection sensitizes the host to enhanced acute DSS-mediated intestinal inflammation.

Lack of association between the occurrence of Crohn's disease and occupational exposure to dairy and beef cattle herds infected with Mycobacterium avium subspecies paratuberculosis

A cross-sectional survey was conducted to identify associations between Crohn's disease (CD) and Mycobacterium avium ssp. paratuberculosis (Map) exposure. A questionnaire was used to collect information on exposure to cattle infected with Map, and personal and family history of CD in dairy and beef cattle producers with and without Map-infected herds, and in veterinarians who did or did not have contact with Map-infected herds. Cases of CD were selected from respondents and matched 1:4 with controls on occupation, age, and sex. Multivariable conditional logistic regression was used to assess associations between Map exposure and CD. There were 3 cases of CD in 702 producers and 4 cases in 774 veterinarians, yielding a prevalence of 0.47%. No association was found between exposure to JD and CD in any phase of the analysis. However, the number of cases of CD is not large and limits the power to detect important differences.

Direct bacterial killing in vitro by recombinant Nod2 is compromised by Crohn's disease-associated mutations

Background

A homeostatic relationship with the intestinal microflora is increasingly appreciated as essential for human health and wellbeing. Mutations in the leucine-rich repeat (LRR) domain of Nod2, a bacterial recognition protein, are associated with development of the inflammatory bowel disorder, Crohn's disease. We investigated the molecular mechanisms underlying disruption of intestinal symbiosis in patients carrying Nod2 mutations.

Methodology/Principal Findings

In this study, using purified recombinant LRR domains, we demonstrate that Nod2 is a direct antimicrobial agent and this activity is generally deficient in proteins carrying Crohn's-associated mutations. Wild-type, but not Crohn's-associated, Nod2 LRR domains directly interacted with bacteria in vitro, altered their metabolism and disrupted the integrity of the plasma membrane. Antibiotic activity was also expressed by the LRR domains of Nod1 and other pattern recognition receptors suggesting that the LRR domain is a conserved anti-microbial motif supporting innate cellular immunity.

Conclusions/Significance

The lack of anti-bacterial activity demonstrated with Crohn's-associated Nod2 mutations in vitro, supports the hypothesis that a deficiency in direct bacterial killing contributes to the association of Nod2 polymorphisms with the disease.

Expression of a Gene Encoding 34.9 kDa PPE Antigen of Mycobacterium avium subsp. paratuberculosis in E. coli

Mycobacterium avium subsp. paratuberculosis (Map) contains PPE family antigens which are Proline and glutamic acid rich and may play important role as T cell antigens. Hence the identification and generation of antigens are necessary for immunological characterization. In the present study, the epitopic region of a unique PPE gene encoding 34.9 kDa protein from Map was amplified by polymerase chain reaction. The gene was cloned into Escherichia coli vector pQE30 UA. The recombinant plasmid designated as pQPPE was transformed into E. coli M15 and induced with IPTG revealed the high level expression of 37.1 kDa His-fusion protein (34.9 kDa PPE and 2.2 kDa His-tag), which was confirmed by immunoblotting. Recombinant PPE protein was then purified by Ni-NTA agarose chromatography. The polyclonal antiserum raised against purified recombinant PPE protein reacted with expressed 37.1 kDa His-fusion protein as well as with Map sonicate. The protein elicited significant delayed type hypersensitivity (DTH) skin reaction in mice sensitized with Map. The results indicated that the recombinant PPE protein of Map was associated with cellular immune response.

Mycobacterium avium subsp. paratuberculosis as a trigger of type-1 diabetes: destination Sardinia, or beyond?

Type 1 diabetes mellitus (T1DM) is a multifactorial autoimmune disease in which the insulin producing beta cell population is destroyed by the infiltrated T lymphocytes. Even though the exact cause of T1DM is yet to be ascertained, varying degree of genetic susceptibility and environmental factors have been linked to the disease progress and outcome. Mycobacterium avium subsp. paratuberculosis (MAP) is an obligate zoonotic pathogen that causes chronic infection of intestines in ruminants, the Johne's disease. MAP that can even survive pasteurization and chlorination has also been implicated to cause similar type of enteritis in humans called Crohn's disease. With the increasing recognition of the link between MAP and Crohn's disease, it has been postulated that MAP is an occult antigen which besides Crohn's could as well be thought to trigger T1DM. Epitope homologies between mycobacterial proteins (Hsp 65) and pancreatic glutamic acid decarboxylase (GAD 65) and infant nutrition studies implicate MAP as one of the triggers for T1DM. PCR and ELISA analyses in diabetic patients from Sardinia suggest that MAP acts as a possible trigger for T1DM. Systematic mechanistic insights are needed to prove this link. Unfortunately, no easy animal model(s) or in-vitro systems are available to decipher the complex immunological network that is triggered in MAP infection leading to T1DM.

[Inflammatory bowel diseases and enteric microbiota]

Intestinal mucosal layers are colonized by a complex microbiota that provides beneficial effects under normal physiological conditions, but is capable of contributing to chronic inflammatory disease such as inflammatory bowel disease (IBD) in susceptible individuals. Studies have shown that the enteric microbiota may drive the development of the gut immune system and can induce immune homeostasis as well as contribute to the development of IBD although the precise etiology is still unknown. Therefore, intestinal microbes seem to play a key role in the disease pathogenesis. Especially, dysbiosis, which is a shift in the composition of enteric microbiota to a nonphysiologic composition, is associated with one or more defects in mucosal immune functions, including microbe recognition, barrier function, intercellular communication, and anti-microbial effector mechanisms. This review focuses on the impact of enteric microbiota on the development and perpetuation of IBD. In addition, interactions with enteric bacteria and mucosal cells, including intestinal epithelial cells, dendritic cells, and T cells, to induce immune responses at mucosal surfaces have been discussed in the point of IBD pathogenesis. Further extension of the knowledge of enteric microbiota may lead to insights on the pathogenesis and new therapeutic strategies for IBD.

Is Mycobacterium avium subsp. paratuberculosis, the cause of Johne's disease in animals, a good candidate for Crohn's disease in man?

Mycobacterium avium subspecies paratuberculosis (MAP) causes Johne's disease or paratuberculosis, a gastro intestinal inflammatory condition in ruminants and other animals, which is similar to Crohn's disease (CD) that occurs in man. The role of MAP in the causation of CD has been under intense investigation in the last few decades. This review summarizes the status of MAP in animals and the food chain and its association with CD in man.

Linking chronic infection and autoimmune diseases: Mycobacterium avium subspecies paratuberculosis, SLC11A1 polymorphisms and type-1 diabetes mellitus

BACKGROUND

The etiology of type 1 diabetes mellitus (T1DM) is still unknown; numerous studies are performed to unravel the environmental factors involved in triggering the disease. SLC11A1 is a membrane transporter that is expressed in late endosomes of antigen presenting cells involved in the immunopathogenic events leading to T1DM. Mycobacterium avium subsp. paratuberculosis (MAP) has been reported to be a possible trigger in the development of T1DM.

METHODOLOGY/PRINCIPAL FINDINGS

Fifty nine T1DM patients and 79 healthy controls were genotyped for 9 polymorphisms of SLC11A1 gene, and screened for the presence of MAP by PCR. Differences in genotype frequency were evaluated for both T1DM patients and controls. We found a polymorphism in the SLC11A1 gene (274C/T) associated to type 1 diabetic patients and not to controls. The presence of MAP DNA was also significantly associated with T1DM patients and not with controls.

CONCLUSIONS/SIGNIFICANCE

The 274C/T SCL11A1 polymorphism was found to be associated with T1DM as well as the presence of MAP DNA in blood. Since MAP persists within macrophages and it is also processed by dendritic cells, further studies are necessary to evaluate if mutant forms of SLC11A1 alter the processing or presentation of MAP antigens triggering thereby an autoimmune response in T1DM patients.

Bacterial and parasitic zoonoses of exotic pets

Zoonoses are estimated to make up to 75% of today's emerging infectious diseases. Many of these diseases are carried and transmitted by exotic pets and wildlife. Exotic animal practitioners must be aware of these risks not only to protect their health but also to safeguard the health of staff and clients. This article reviews selected bacterial and parasitic zoonoses associated with exotic animals.

Oligonucleotide microarray technology and its application to Mycobacterium avium subsp. paratuberculosis research: a review

Microarrays represent a modern powerful technology, which have potential applications in many areas of biological research and provide new insights into the genomics and transcriptomics of living systems. The aim of this review is to describe the application of microarray technology for Mycobacterium avium subsp. paratuberculosis (MAP) research. The main focus points include a summary of results obtained for MAP using microarrays, examination of the fields of MAP research which are currently being investigated and possible areas of future research. This article is divided into two parts according to the type of nucleic acid used for array hybridisation. Articles related to MAP research using microarray technology are then divided according to the field of study, such as comparative genome analysis, diagnostics, expression or environmental studies.

Optimization of a phage amplification assay to permit accurate enumeration of viable Mycobacterium avium subsp. paratuberculosis cells

A commercially available phage amplification assay, FASTPlaqueTB (Biotec Laboratories, Ipswich, United Kingdom), when used according to the manufacturer's instructions, does not permit accurate enumeration of Mycobacterium avium subsp. paratuberculosis. The aim of this study was to optimize the phage amplification assay conditions to permit accurate quantification of viable M. avium subsp. paratuberculosis cells. The burst time for M. avium subsp. paratuberculosis was initially determined to inform decisions about optimal incubation time before plating, and then other test parameters were altered to evaluate how the correlation between plaque and colony counts was affected. The D29 mycobacteriophage replicates more slowly in M. avium subsp. paratuberculosis than in Mycobacterium smegmatis (used to optimize the commercial test originally), and the mean burst time for four M. avium subsp. paratuberulosis strains was 210 +/- 36.8 min at 37 degrees C compared to 63 +/- 17.5 min for M. smegmatis mc(2) 155. To achieve 100% correlation between plaque and colony counts, the optimized phage assay includes the following: (i) resuspension of the samples to be tested in Middlebrook 7H9 broth containing 10% oleic acid-albumin-dextrose-catalase and 2 mM calcium chloride, followed by overnight incubation at 37 degrees C before performance of the phage assay; (ii) a 2-h incubation of the sample with D29 mycobacteriophage before viricide treatment; and (iii) a further 90-min incubation after viricide treatment and neutralization up to the burst time (total incubation time, 210 min) before plating with M. smegmatis mc(2) 155 in 7H9 agar. The optimized phage amplification assay was able to detect 1 to 10 CFU/ml of M. avium subsp. paratuberculosis in spiked milk or broth within 48 h, as demonstrated by the results of several blind trials.

Development of a bovine ileal cannulation model to study the immune response and mechanisms of pathogenesis of paratuberculosis

An ileal cannulation model was developed in conjunction with a flow cytometric assay to gain a better understanding of the mechanisms of immunopathogenesis of Johne's disease caused by Mycobacterium avium subsp. paratuberculosis. Initial studies with calves showed that M. avium subsp. paratuberculosis DNA is detectable by PCR in ileal biopsies during the first months following experimental infection. Inflammatory lesions were not detected on endoscopic evaluation up to 8 months postexperimental infection. M. avium subsp. paratuberculosis DNA was detected in multiple tissues at necropsy 8 months postinfection. Examination of the activation status of epithelial lymphocytes from the jejunum and ileum from infected and control animals at necropsy revealed that none of the major subsets of lymphocytes (NK, CD2(+), and CD2(-) gammadelta T lymphocytes, or CD4 and CD8 alphabeta T lymphocytes) expressed activation molecules CD25, CD26, CD71, ACT1, or ACT16. Subsets of CD4 and CD8 T lymphocytes from control and infected animals expressed CD26. The majority of CD4 and CD8 T lymphocytes expressed CD45R0, the memory T-lymphocyte marker. An immune response to M. avium subsp. paratuberculosis was detected by 3 months postinfection, dominated by a strong proliferative response of CD4 memory T lymphocytes. The findings indicate an immune response develops following initial exposure to M. avium subsp. paratuberculosis that controls but does not eliminate the pathogen. This persistence of M. avium subsp. paratuberculosis possibly leads to erosion and dysregulation of protective immunity at later time points postinfection. Continuous access to the ileum offers an opportunity to elucidate the cellular and molecular events leading to immune dysregulation and development of chronic inflammatory ileitis.