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 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.