The amyloid oligomer modulator anle138b has disease modifying effects in a human IAPP transgenic mouse model of type 2 diabetes mellitus (hIAPP Ob/Ob mice)

Abstract

Aims/HypothesisType 2 diabetes mellitus (T2DM) is a common metabolic disease, characterized by impaired insulin action, often called "insulin resistance", in conjunction with a decline in insulin secretion by the pancreatic islet beta cells, referred to as "beta cell failure". Both conditions contribute to causing hyperglycemia, which is the central feature of T2DM. Cytotoxic aggregates of the beta cell hormone human islet amyloid polypeptide (hIAPP), promote T2DM pathogenesis by damaging the pancreatic islet beta cells and reducing insulin secretion. Anle138b is an amyloid oligomer modulator with demonstrated disease-modifying properties in mouse models of neurodegenerative diseases linked to protein aggregation, and is currently in a phase 2 clinical trial. We therefore tested whether anle138b can reduce hyperglycemia in a severe hIAPP transgenic mouse model of T2DM. MethodsAnle138b was administered orally via dietary admixture to male hIAPP Ob/Ob mice and Ob/Ob controls; blood glucose-, insulin-, and glycated hemoglobin (HbA1c) levels were measured at different timepoints over 34 weeks; in addition, the effects of anle138b on the histomorphology of the pancreatic islets was determined. Finally, anle138b effects on mitochondrial toxicity of hIAPP aggregates was assessed in vitro. ResultsOral administration of anle138b in male hIAPP Ob/Ob mice potently reduced hyperglycemia and glycated HbA1c levels compared to non-treated mice (at 34 weeks, mean glucose level non-treated: 30 {+/-} 1.3 mM, treated: 15 {+/-} 2.2 mM (p < 0.001); at 32 weeks, mean HbA1c level non-treated: 77 {+/-} 3.3 mM/M, treated: 41 {+/-} 5.3 mM/M (p < 0.01)), in a hIAPP-dependent way. In addition, anle138b increased both the number of pancreatic islets as well as the overall islet beta cell mass (by 54% and 58%, respectively) in hIAPP Ob/Ob mice. In vitro, anle138b inhibited toxic effects of hIAPP on mitochondria, such as mitochondrial swelling (decreased by 92%, p < 0.01), release of cytochrome c (decreased by 63.7%, p < 0.001) and lowered mitochondrial membrane potential (increased by 62%, p < 0.001). Conclusions/InterpretationCollectively, our results indicate that anle138b is a promising clinical drug candidate for preserving islet function and reducing hyperglycemia in T2DM, in part by mitigating mitochondrial dysfunction. Research in ContextO_ST_ABSWhat is already known about this subject?C_ST_ABSO_LIType 2 diabetes mellitus (T2DM) is characterized by hyperglycemia, which stems from impaired insulin action coupled with declining insulin secretion from pancreatic islet beta cells. C_LIO_LIAggregation of the beta cell hormone human islet amyloid polypeptide (hIAPP) plays a crucial role in the loss and dysfunction of the insulin-secreting beta cells. C_LIO_LIThe small-molecule anle138b effectively modulates the aggregation of amyloidogenic proteins in neurodegenerative conditions such as Alzheimers and Parkinsons disease. C_LI What is the key question?O_LICan the oligomer modulator anle138b ameliorate the diabetic phenotype in a severe hIAPP transgenic mouse model of T2DM (hIAPP Ob/Ob) ? C_LIO_LIWhat are the new findings? C_LIO_LIOral treatment of hIAPP Ob/Ob mice with anle138b causes reduced hyperglycemia and reduced glycated hemoglobin (HbA1c) levels, in a hIAPP-dependent manner. C_LIO_LIAnle138b increases pancreatic islet number and beta cell mass and restores the inverse relation between insulin and glucose in hIAPP Ob/Ob mice. C_LIO_LIIn vitro anle138b inhibits toxic effects of hIAPP aggregates on mitochondria. C_LI How might this impact on clinical practice in the foreseeable future?O_LIAnle138b could be introduced as a promising clinical drug candidate for slowing down disease progression of T2DM. C_LI