Objective
The long term objective of this proposal is to 1) identify new ways to improve overall beta cell health in Type 1 diabetes (T1D) and 2) identify a non-invasive biomarker to detect early onset beta cell dysfunction/stress in T1D. This proposal will exploit the idea of altered beta cell-to-beta cell communication mediated by small extracellular vesicles (EVs) and their pathophysiological role in mediating beta cell dysfunction. Moreover, we will assess the use of circulating beta cell-derived EVs as a novel means to monitor progressing beta cell failure. The findings of this study will provide tremendous insight into the pathophysiology of T1D with the goal of utilizing this knowledge to devise new therapeutic modalities and biomarkers for T1D.
Background Rationale
Type 1 diabetes (T1D) is an autoimmune disorder that afflicts over 1.6 million Americans including over 200,000 children and adolescents. T1D is characterized by hyperglycemia mediated by insulin deficiency due to progressive dysfunction of insulin producing pancreatic beta cells and eventual autoimmune-mediated beta cell loss. Treatment strategies include daily insulin treatments with continuous glucose monitoring. The development of T1D occurs several years prior to clinical diagnosis, with evidence suggesting alterations in normal beta cell function and immune cell activation. In recent years, specific beta cell stress responses have been shown to be activated early in the pathogenesis of T1D with evidence suggesting that cellular communication between beta cells and other cell types is necessary during initial stages of disease development. Therefore, a deeper understanding of the molecular underpinnings of T1D are warranted in order to devise novel prediction and treatment strategies. This application takes a two-pronged approach at understanding the impact of beta cell derived small extracellular vesicles (EVs) on the pathophysiology of T1D and their utility as circulating biomarkers of early onset T1D. EVs are defined as small membrane-derived nanovesicles which are secreted by most cell types and harbor a heterogenous mix of different cellular cargoes. EVs have been shown to participate in both long and short range communication with varying cell types and tissues through the exchange of these bioactive cargoes. Moreover, the content of EVs have been found to be altered based on the state of the cell or tissue of origin (stressed conditions or disease states). Our preliminary data show that beta cell stress in the form of inflammation alters the content of beta cell-derived EVs which have the capacity to induce beta cell dysfunction. Therefore, in this application we seek to further uncover the molecular mechanism of pro-inflammatory induced beta cell derived EVs in mediating beta cell dysfunction with the goal of devising novel EV-based therapeutic strategies to improve overall beta cell health in T1D. Moreover, we identified a highly enriched protein, CXCL10, in these pro-inflammatory EVs which could serve as an early prognostic indicator of beta cell stress in T1D.
Description of Project
Type 1 diabetes (T1D) arises from the autoimmune destruction of the insulin producing pancreatic beta cells resulting in hyperglycemia and insulin dependence. Therapeutic strategies to prevent T1D onset have focused primarily on immunomodulatory therapies to target beta cell autoimmunity with only limited success. Recent studies have suggested that beta cells are active contributors to the pathogenesis of T1D through their own demise and thus have the potential to serve as a new targets of therapeutic intervention. Diabetogenic stressors including inflammation have been shown to induce beta cell dysfunction however the impact of these stressors on the communication between the beta cells and their role in mediating beta cell failure and death is unknown. We propose in this application that altered communication amongst beta cells are mediated in part by the exchange of toxic cellular cargoes carried in small lipid membrane derived extracellular vesicles (EVs). Our work as well as others, have shown that a pro-inflammatory environment induces alterations in EV content and that these inflammatory EVs have the capacity to induce beta cell dysfunction and alterations in the islet transcriptome. Thus, in this proposal, we seek to determine further mechanistic insights into the role of inflammatory EVs in the pathophysiology of T1D with the long-term goal of illuminating potentially new EV-based therapeutic modalities to prevent/restore loss of functional beta cell mass. Moreover, there is currently a need for novel biomarkers to detect and monitor early onset beta cell stress. Based on our preliminary data, we will exploit the use of circulating EVs as a non-invasive, early prognostic indicator of beta cell stress through the assessment of CXCL10 enrichment in beta cell-derived plasma EVs in patients with progressing T1D.
Anticipated Outcome
We anticipate that the proposed studies will advance our knowledge on the molecular mechanisms of pro-inflammatory-mediated beta cell EVs and their role in inducing beta cell dysfunction in T1D. The identification of additional pathways that link beta cell EVs to beta cell dysfunction will allow for new methodologies for targeted therapeutic intervention to prevent/restore loss of functional beta cell mass in T1D. Moreover, we will validate our proposed biomarker of early onset beta cell dysfunction in circulating plasma-derived EVs from patients at varying stages of T1D pathology.
Relevance to T1D
This work has great significance to T1D as the overall goal is to understand new approaches to restore/prevent loss of functional beta cell mass in T1D. The focus of this proposal is on a new concept of inter-islet communication mediated by extracellular vesicles (EVs) and their role in disease progression. Understanding the physiological and molecular contribution of EVs will aid in identification of novel EV-based therapeutic strategies to improve overall beta cell health in T1D. As the premise of this work is to exploit the idea of early onset beta cell dysfunction as an initiating event in the pathogenesis of T1D, we took the approach to assess altered beta cell-derived EVs in circulation as early predictive biomarkers that reflect this pre-symptomatic stage. Moreover, our ability to detect early onset beta cell stress and the underlying molecular defects in T1D pathogenesis will inevitably improve the timing of therapeutic intervention and give rise to new therapeutic modalities.