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Mycobacterium aviumsubsp.paratuberculosisprotein MAP 3865c may mimic the pancreatic islet autoantigen Znt8 relevant in type 1 diabetes
Full text linkThe environmental factors at play in the pathogenesis of type 1 diabetes (T1D) remain enigmatic.Mycobacterium aviumsubspeciesparatuberculosis(MAP) is transmitted from dairy herds to humans through food contamination. MAP causes an asymptomatic infection which 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 searched 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 indirect ELISA. 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
Zinc Transporter 8 and MAP3865c Homologous Epitopes are Recognized at T1D Onset in Sardinian Children.
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Are Mycobacterium avium subsp. paratuberculosis and Epstein-Barr virus triggers of multiple sclerosis in Sardinia?
No full textEvaluation of the humoral response against mycobacterial peptides, homologous to MOG35-55, in multiple sclerosis patients
No full textBacillus 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
Sardinian Type 1 diabetes patients, Transthyretin and <it>Mycobacterium avium subspecies paratuberculosis</it> infection
Full text linkAbstract 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 β-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.</p
Association of Mycobacterium avium subsp. paratuberculosis with multiple sclerosis in Sardinian patients.
No full textProinsulin and MAP3865c homologous epitopes are a target of antibody response in new-onset type 1 diabetes children from continental Italy
No full textMycobacterium 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 MAP2404c(70)-(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--gbp(157)-(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
Antibodies Recognizing Mycobacterium avium paratuberculosis Epitopes Cross-react with the Beta-Cell Antigen ZnT8 in Sardinian Type 1 Diabetic Patients
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