Creating a Soluble Binder to Endothelin-1 Based on the Natural Ligand Binding Domains of the Endothelin-1 (G-Protein-Coupled) Receptor

Investigating the specificity of endothelin-traps as a potential therapeutic tool for endothelin-1 related disorders

BACKGROUND

Endothelin (ET)-traps are Fc-fusion proteins with a design based on the physiological receptors of ET-1. Previous work has shown that use of the selected ET-traps potently and significantly reduces different markers of diabetes pathology back to normal, non-disease levels.

AIM

To demonstrate the selected ET-traps potently and significantly bind to ET-1.

METHODS

We performed phage display experiments to test different constructs of ET-traps, and conducted bio-layer interferometry binding assays to verify that the selected ET-traps bind specifically to ET-1 and display binding affinity in the double-digit picomolar range (an average of 73.8 rM, n = 6).

RESULTS

These experiments have confirmed our choice of the final ET-traps and provided proof-of-concept for the potential use of constructs as effective biologics for diseases associated with pathologically elevated ET-1.

CONCLUSION

There is increased need for such therapeutics as they could help save millions of lives around the world.

ET-traps offer a potential therapeutic tool for use in different autoimmune diseases

Research shows that endothelin (ET)-traps are a potential therapy for diabetes. Given that type 1 diabetes mellitus (T1DM) is an autoimmune disorder, ET-traps could also have an efficacious, therapeutic effect on other autoimmune diseases associated with pathologically elevated ET-1. Here, we describe those different autoimmune diseases that might benefit from a tool such as ET-traps, which potently sequester these elevated levels of ET-1. We also discuss the current use of ET receptor (ETR) antagonists and the associated adverse effects, and how ET-traps are associated with no toxicity and potentially offer a superior alternative. ET-traps could be used against different autoimmune diseases and, therefore, are a novel therapeutic tool for such conditions.

Endothelin-1 traps potently reduce pathologic markers back to basal levels in an in vitro model of diabetes

Background

Diabetes mellitus is a group of metabolic disorders in which there are high blood glucose levels over a prolonged period. Diabetes is one of many diseases associated with pathologically elevated levels of endothelin (ET)-1. We have recently proposed the development of ET-traps, which are an antibody - based fusion protein that potently bind and sequester pathologically elevated levels of endothelin-1.

Methods

We constructed ET-traps that were found to be very potent binders to ET-1, with a K_D of 32.5ρM. We then treated human retinal microvascular endothelial cells (HRMECs), which are an in vitro model of glucose induced cellular damage, with 10 nM ET-1 or high glucose levels (25 mM).

Results

In this study, we investigated the effects of our ET-trap constructs on the expression levels of both collagen 4α1 and fibronectin, which are both important pathologic markers in diabetes. Treating HRMECs with 10 nM ET-1 or 25 mM glucose significantly induces the expression of the ECM proteins fibronectin and collagen 4α1, as is found in chronic diabetic complications; Incubation of the cells with the ET-traps significantly prevented the increased expression of fibronectin and collagen 4α1 back to basal levels. This was found with both mRNA and protein expression levels of the two ECM proteins.

Conclusion

Our results provide the first evidence of the efficacy of ET-traps in reducing pathologic markers in an in vitro model (of diabetes). Further research is warranted to determine the efficacy of ET-traps as a therapeutic tool for diabetes, which is a major public health burden around the world.