Archives of autoimmune diseases最新文献

The protein hormone adiponectin regulates glucose and fatty acid metabolism by binding to two PAQR-family receptors (AdipoR1 and AdipoR2). Both receptors feature a C-terminal segment which is released by proteolysis to form a freely circulating C-terminal fragment (CTF) found in the plasma of normal individuals but not in some undefined diabetes patients. The AdipoR1-CTF_344-376 is a competitive inhibitor of tumor necrosis factor α cleavage enzyme (TACE) but it contains a shorter peptide domain (AdipoR1 CTF_351-362) that is a strong non-competitive inhibitor of insulin-degrading enzyme (IDE). The link between adiponectin receptor fragmentation and diabetes pathology is unclear but could lead to new therapeutic strategies. We therefore investigated physiological variations in the concentrations of CTF in non-obese diabetic (NOD/ShiLtJ) mice and C57BL/6 mice with diet-induced obesity (DIO) as models of diabetes types 1 and 2, respectively. We tested for changes in adiponectin receptor signaling, immune responses, disease progression, and the abundance of neutralizing autoantibodies. Finally, we administered exogenous AdipoR1-CTF peptides either containing or lacking the IDE-binding domain. We observed the more pronounced CTF shedding in the TACE-active NOD mice, which represents an inflammatory autoimmune phenotype, but fragmentation was also observed to a lesser extent in the DIO model. Autoantibodies to CTF were detected in both models. Neither exogenous CTF peptide affected IgG-CTF plasma levels, body weight or the conversion of NOD mice to diabetes. The pattern of AdipoR1 fragmentation and autoantibody production under physiological conditions of aging, DIO, and autoimmune diabetes therefore provides insight into the association adiponectin biology and diabetes.

Background: Diabetes is a complex, multi-symptomatic disease whose complications drives increases in healthcare costs as the diabetes prevalence grows rapidly world-wide. Real-world electronic health records (EHRs) coupled with patient biospecimens, biological understanding, and technologies can characterize emerging diagnostic autoimmune markers resulting from proteomic discoveries.

Methods: Circulating autoantibodies for C-terminal fragments of adiponectin receptor 1 (IgG-CTF) were measured by immunoassay to establish the reference range using midpoint samples from 1862 participants in a 20-year observational study of type 2 diabetes and cardiovascular arterial disease (CVAD) conducted by the Fairbanks Institute. The White Blood Cell elastase activity in these patients was assessed using immunoassays for Bikunin and Uristatin. Participants were assigned to four cohorts (healthy, T2D, CV, CV+T2D) based on analysis of their EHRs and the diagnostic biomarkers values and patient status were assessed ten-years post-sample.

Results: The IgG-CTF reference range was determined to be 75-821 ng/mL and IgG-CTF out-of-range values did not predict cohort or comorbidity as determined from the EHRs at 10 years after sample collection nor did IgG-CTF demonstrate a significant risk for comorbidity or death. Many patients at sample collection time had other conditions (hypertension, hyperlipidemia, or other risk factors) of which only hypertension, Uristatin and Bikunin values correlated with increased risk of developing additional comorbidities (odds ratio 2.58-13.11, P<0.05).

Conclusions: This study confirms that retrospective analysis of biorepositories coupled with EHRs can establish reference ranges for novel autoimmune diagnostic markers and provide insights into prediction of specific health outcomes and correlations to other markers.