Lack of humoral response against Helicobacter pylori peptides homologous to human ZnT8 in Hashimoto's thyroiditis patients.

INTRODUCTION: The Helicobacter pylori (HP) reinfection rate seems to be higher in developing countries than in developed ones. An increased seroprevalence of HP has also been reported in patients with type 1 diabetes (T1D) and Hashimoto's thyroiditis (HT). Mycobacterium avium subsp. paratuberculosis (MAP) has been linked to both T1D and HT. Quite a few lines of evidence indicate that autoantibodies against several epitopes belonging to human zinc transporter 8 (ZnT8) cross-recognize the homologous MAP3865c epitopes in both T1D and HT patients. HP may play a role in HT disease, most likely acting through a molecular mimicry mechanism that targets ZnT8 as reported for MAP and the two autoimmune diseases. METHODOLOGY: An enzyme-linked immunosorbent assay (ELISA) has been developed for the detection of antibodies against several epitopes deriving from HP proteins, which are highly homologous to the immunodominant ZnT8 peptides previously identified: ZnT8178-186 and ZnT8186-194. RESULTS: None of the HP peptides tested were significantly recognized when the humoral responses of 92 HT patients and 91 healthy volunteers were analyzed. CONCLUSIONS: These findings do not support a triggering role for HP (through ZnT8 mimicking) in HT. If a molecular mimicry phenomenon is taking place, it involves a different self-antigen. Moreover, the negative outcome of the experiments performed stresses the fact that sharing stretches of sequence homology is relevant, but not enough to trigger an antibody-mediated cross-recognition.

Proinsulin and MAP3865c homologous epitopes are a target of antibody response in new-onset type 1 diabetes children from continental Italy.

Mycobacterium avium subspecies paratuberculosis (MAP) asymptomatic infection is speculated to play a role in type 1 diabetes (T1D) among Sardinian subjects. Data obtained analyzing a pediatric population from mainland Italy lends support to the hypothesis, which envisions MAP as an environmental factor at play in T1D pathogenesis. Aiming to investigate the likelihood of cross-recognition between linear determinants shared by self (proinsulin) and non-self (MAP) proteins, 59 children with new onset T1D and 60 healthy controls (HCs) from continental Italy were enrolled in the study. Serum samples were subjected to indirect enzyme-linked immunosorbent assay (ELISA) for the presence of antibodies (Abs) toward four homologues MAP/proinsulin epitopes. The rate of MAP infection (42.4% in T1D children and 5% in HCs; p < 0.0001) was estimated searching for Abs against MAP specific protein MptD. The homologous MAP2404c70-85 and proinsulin (PI)46-61 peptides were recognized by 42.4 and 39% of new-onset T1D children and only in 5% of HCs (AUC = 0.76, AUC = 0.7, p < 0.0001); whereas the prevalence of Abs against MAP 1,4-α-gbp157-173 and PI64-80 peptides was 45.7 and 49.1% in new-onset T1D children, respectively, compared with 3.3% of HCs (AUC = 0.74 and p < 0.0001 in both). Pre-incubation of MAP Ab-positive sera with proinsulin peptides was able to block the binding to the correspondent MAP epitopes, thus showing that Abs against these homologous peptides are cross-reactive. MAP/Proinsulin Ab mediated cross-recognition, most likely via molecular mimicry, maybe a factor in accelerating and/or initiating T1D in MAP-infected children. Indeed, it is known that anti-proinsulin and anti-Insulin autoantibodies are the earliest to appear.

Human interferon regulatory factor 5 homologous epitopes of Epstein-Barr virus and Mycobacterium avium subsp. paratuberculosis induce a specific humoral and cellular immune response in multiple sclerosis patients.

BACKGROUND: A large number of reports indicate the association of Epstein-Barr virus (EBV), and Mycobacterium avium subsp. paratuberculosis (MAP) with multiple sclerosis (MS). OBJECTIVE: To gain a better understanding of the role of these two pathogens, we investigated the host response induced by selected antigenic peptides. METHODS: We examined both humoral and cell-mediated responses against peptides deriving from EBV tegument protein BOLF1, the MAP_4027 and the human interferon regulatory factor 5 (IRF5424-434) homolog in several MS patients and healthy controls (HCs). RESULTS: Antibodies against these peptides were highly prevalent in MS patients compared to HCs. Concerning MS patients, BOLF1305-320, MAP_402718-32 and IRF5424-434 peptides were able to induce mainly Th1-related cytokines secretion, whereas Th2-related cytokines were down-regulated. Flow cytometry analyses performed on a subset of MS patients highlighted that these peptides were capable of inducing the release of pro-inflammatory cytokines: IFN-γ and TNF-α by CD4(+) and CD8(+) T lymphocytes, and IL-6 and TNF-α by CD14(+) monocyte cells. CONCLUSION: Our data demonstrated that both EBV and MAP epitopes elicit a consistent humoral response in MS patients compared to HCs, and that the aforementioned peptides are able to induce a T-cell-mediated response that is MS correlated.

Evaluation of the humoral response against mycobacterial peptides, homologous to MOG35₋55, in multiple sclerosis patients.

Bacillus Calmette-Guérin (BCG) and Mycobacterium avium subspecies paratuberculosis (MAP) have been associated with multiple sclerosis (MS). Clinical data indicates that BCG vaccination exerts anti-inflammatory effects in MS; conversely, MAP is thought to be one of the possible infectious factors responsible of MS through a molecular mimicry mechanism. A peptide-based indirect ELISA was used to detect antibodies against the encephalitogenic myelin oligodendrocyte glycoprotein (MOG)35-55 epitope, and two mycobacterial peptides sharing sequence homology with the latter: MAP_2619c352-361/BCG_1224355-364 and BCG_3329c64-74. Among 40 MS patients and 39 healthy volunteers included in the study, only MOG35-55 was capable of inducing a significantly higher humoral response in MS subjects compared to controls. Indeed, 11 out of 40 MS subjects (27.5%) and only 2 out of 39 controls (5%) were antibody-positive for MOG35-55 (p=0.01, AUC=0.65). These findings strengthen the importance of MOG35-55 in MS pathogenesis. The MAP and BCG MOG-homologues epitopes investigated were not recognized in MS patients. Overall, the results allow us concluding that sharing homology of linear epitopes is necessary but not sufficient to induce antibody-mediated cross-reactivity.

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.

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 ß-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.

Epstein-Barr virus and Mycobacterium avium subsp. paratuberculosis peptides are cross recognized by anti-myelin basic protein antibodies in multiple sclerosis patients.

Epstein-Barr virus and Mycobacterium avium subsp. paratuberculosis (MAP) have been associated to multiple sclerosis (MS). We searched for antibodies against the homologous peptides Epstein-Barr virus nuclear antigen 1 (EBNA1)400-413, MAP_0106c protein (MAP)121-132, and myelin basic protein (MBP)85-98 on a MS Sardinian cohort, showing that these antibodies are highly prevalent among MS patients compared to healthy controls. Competitive assay demonstrated that antibodies recognizing EBNA1400-413 and MAP121-132 cross-react with MBP85-98, possibly through a molecular mimicry mechanism. Indeed, the fact that peptides from different pathogens can be cross-recognized by antibodies targeting self-epitopes supports the hypothesis that EBV and MAP might trigger autoimmunity through a common target.

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.

Antigenic epitopes of MAP2694 homologous to T-cell receptor gamma-chain are highly recognized in multiple sclerosis Sardinian patients.

Mycobacterium avium ss. paratuberculosis (MAP) is an intracellular pathogen recently associated with multiple sclerosis (MS). Aiming to identify immunodominant epitopes belonging to MS related protein MAP2694 (UniProt accession no. Q73WG6), we investigated the binding activity of selected peptides against MS Sardinian sera. An overlapping 9-mers peptide library was synthesized spanning the entire aminoacidic sequence of the protein. Peripheral blood was collected from 47 MS patients and 42 sex and age matched healthy volunteers and subjected to enzyme-linked immunosorbent assay (ELISA) in order to investigate the reaction against the linear peptides generated. Two out of 58 synthetic 9-mers were strongly recognized by MS patients' antibodies compared to controls. A competitive inhibition assay demonstrated that these two epitopes are immunodominant antibody targets within MAP2694 protein, as sera pre-adsorbed with these peptides were able to significantly block the antibody reaction to the MAP2694 protein, even if at a lesser extent than MAP2694 protein itself.

EBNA-1 IgG titers in Sardinian multiple sclerosis patients and controls.

Multiple sclerosis (MS) is thought to be triggered by environmental factors acting on a genetic predisposition. Sardinians share a homogeneous genetic background and boast one of the highest MS prevalence worldwide. We investigated Epstein-Barr virus (EBV) antibody prevalence in Sardinian population by ELISA. Our results show a higher serum prevalence of EBNA-1 IgG in MS patients compared to healthy controls. Moreover, analyzing a subset of patients treated for 6 months with IFN-ß, we observed a decrease in their EBNA-1 specific IgG titers. These results confirm previous findings and strengthen the association between EBV and MS in Sardinia.

Zinc transporter 8 and MAP3865c homologous epitopes are recognized at T1D onset in Sardinian children.

Our group has recently demonstrated that Mycobacterium avium subspecies paratuberculosis (MAP) infection significantly associates with T1D in Sardinian adult patients. Due to the potential role played by MAP in T1D pathogenesis, it is relevant to better characterize the prevalence of anti-MAP antibodies (Abs) in the Sardinian population, studying newly diagnosed T1D children. Therefore, we investigated the seroreactivity against epitopes derived from the ZnT8 autoantigen involved in children at T1D onset and their homologous sequences of the MAP3865c protein. Moreover, sera from all individuals were tested for the presence of Abs against: the corresponding ZnT8 C-terminal region, the MAP specific protein MptD, the T1D autoantigen GAD65 and the T1D unrelated Acetylcholine Receptor. The novel MAP3865c281-287 epitope emerges here as the major C-terminal epitope recognized. Intriguingly ZnT8186-194 immunodominant peptide was cross-reactive with the homologous sequences MAP3865c133-141, strengthening the hypothesis that MAP could be an environmental trigger of T1D through a molecular mimicry mechanism. All eight epitopes were recognized by circulating Abs in T1D children in comparison to healthy controls, suggesting that these Abs could be biomarkers of T1D. It would be relevant to investigate larger cohorts of children, followed over time, to elucidate whether Ab titers against these MAP/Znt8 epitopes wane after diagnosis.

Association of Mycobacterium avium subsp. paratuberculosis and SLC11A1 polymorphisms in Sardinian multiple sclerosis patients.

INTRODUCTION: Recent findings propose that Mycobacterium avium subsp. paratuberculosis (MAP) infection could act as risk factor in favoring multiple sclerosis (MS) progression. SLC11A1 is a gene associated with mycobacterial survival in the host and it may be involved in the induction and maintenance of autoimmune disease. METHODOLOGY: In this preliminary study, 100 MS patients and 100 healthy controls (HCs) from Sardinia were enrolled. Eight single nucleotide polymorphisms (SNPs) in the SLC11A gene were searched by PCR RFLP-genotyping. IS900 specie specific PCR was undertaken to search for MAP presence. Indirect ELISA was performed to asses if MS patients displayed a stronger humoral response against MAP2694 protein compared to the HCs. RESULTS: Only rs2276631 SNP was associated with MS. MAP DNA was detected in 23 out of 100 MS patients (23%) and in 7 out of 100 HCs (7%). A strong humoral response against MAP2694 protein was detected in 36% of MS patients and only in 3% of HCs. A correlation between ELISA sero-positivity and the rs2276631 SNP was also found. CONCLUSION: Our preliminary results suggest that the Sardinian population might be prone to develop autoimmune disease due to polymorphisms in immunomodulating the SLC11A1 gene, which is important in the immune response against intracellular bacteria such as MAP.

A Sardinian map for multiple sclerosis.

Multiple sclerosis (MS) is a complex autoimmune disease of the CNS. At present, MS etiology remains unknown, but it is believed to be caused by environmental factors acting on a genetic predisposition. Several studies suggest that different microorganisms could play a role in triggering autoimmunity, through immunological cross-reactivity or molecular mimicry. An overview of the knowledge regarding the bacteria involved in MS is given, placing emphasis on the newest candidate proposed: Mycobacterium avium subsp. paratuberculosis. This review will focus on discussing several arguments that might support a causal role for Mycobacterium avium subsp. paratuberculosis as an etiologic agent in MS. Additionally, a possible mechanism is postulated attempting to explain how the bacteria could initiate autoimmunity.

Sardinian Type 1 diabetes patients, Transthyretin and Mycobacterium avium subspecies paratuberculosis infection.

BACKGROUND: Mycobacterium avium subsp. paratuberculosis (MAP) is the cause of Johne's disease, an enteric granulomatous disease. Recently, MAP has been associated with different autoimmune diseases such as Crohn's disease, type 1 diabetes (T1D) and multiple sclerosis. Transthyretin (TTR) is a plasma transport protein for thyroid hormone and forms a complex with retinol-binding protein. Reduced TTR plasma levels in MAP infected ovines have been reported.TTR exerts also a functional role in the pancreas promoting insulin release and protecting ß-cells from death.Our objective was to identify a protein that could be used as a diagnostic marker of T1D for determining disease progression and monitoring at-risk patients. We postulate that serological TTR levels would be reduced in T1D MAP exposed patients. Our hypothesis is based on the observation of cases of T1D patients with decreased TTR levels beside the reduced TTR plasma levels in ovines with Johne's disease.We quantified the plasma protein levels of TTR in 50 people with T1D and 51 age-matched healthy controls (HCs) by means of enzyme-linked immunosorbent assays (ELISA). FINDINGS: Our pilot study showed that plasma TTR levels were not significantly lower/higher in T1D Sardinian cases compared to the HCs. CONCLUSION: These preliminary data indicate that plasma TTR may not be a good candidate biomarker for T1D diagnosis and further studies to elucidate the possible link are needed.

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 ß-cells.

Are Mycobacterium avium subsp. paratuberculosis and Epstein-Barr virus triggers of multiple sclerosis in Sardinia?

Sardinia acts as an ideal setting for multiple sclerosis (MS) studies because its prevalence of MS is one of the highest worldwide. Several pathogens have been investigated amongst 119 Sardinian MS patients and 117 healthy controls to determine whether they might have a role in triggering MS in genetically predisposed individuals. Mycobacterium avium subsp. paratuberculosis (MAP) and Epstein Barr virus DNA were detected in 27.5% and 17.3%, respectively, of the MS patients. Moreover an extremely high humoral immune response against MAP recombinant protein MAP FprB (homologous to human myelin P0) was observed, whereas no significant results were found against Mycobacterium tuberculosis FprA and Helicobacter pylori HP986 protein.

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 ß-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.

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.

Molecular characterization of Sardinian Mycobacterium tuberculosis isolates by IS6110 restriction fragment length polymorphism, MIRU-VNTR and rep-PCR.

An evaluation of the utility of rep PCR typing compared to the 15 loci discriminatory set of MIRU-VNTR was undertaken. Twenty-nine isolates of Mycobacterium tuberculosis from patients were examined. Genomic DNA was extracted from the isolates by standard method. The number of copies of tandem repeats of the 15 MIRU-VNTR loci was determined by PCR amplification and agarose gel electrophoresis of the amplicons. M. tuberculosis outbreak-related strains were distinguished from other isolates. MIRU-VNTR typing identified 4 major clusters of strains. The same isolates clustered together after RFLP typing, but rep-PCR identified only 3 of them. The concordance between RFLP and MIRU-VNTR typing was complete, with the exception of two isolates with identical RFLP patterns that differed in the number of tandem repeat copies at two MIRU-VNTR alleles. A further isolate, even sharing the same RFLP pattern, differed by one repeat from the rest of its cluster. We also tested the use of an automated rep-PCR for clinical laboratory applications but it failed to identify the link between two pairs of epidemiologically related strains clustered by the other 2 techniques. For superior discrimination, ease of comparison of results and lower cost, MIRU-VNTR typing should be the favored PCR-based typing tool.

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.