Degeneration of the intervertebral disc (IVD) is a leading contributor towards back pain, an epidemic that costs billions of dollars in the US. The IVD consists of a proteoglycan(PG)-rich nucleus pulposus (NP) surrounded by a collagenous annulus fibrosus (AF) that together provide support and transmit complex loads. The IVD degenerative cascade involves a multifactorial progression of biological, biochemical, and structural changes that lead to the collapse of the disc structure and to compromised mechanical function. Despite its significant public health impact, the pathophysiology of disc degeneration remains unclear. The accumulation of Advanced Glycation End-products (AGEs) is associated with aging and degeneration of the IVD. AGEs form through nonenzymatic glycation, where extracellular sugars undergo Maillard rearrangement with amino acids to become protein adducts and crosslinks. AGES are known to impair the mechanical function of matrix proteins. Beyond matrix modifications, AGEs activate the cellular Receptor for Advanced Glycation Endproducts (RAGE), and RAGE signaling perpetuates immune and inflammatory responses. Because the IVD is avascular and has relatively low tissue remodeling, IVD tissues are susceptible to accumulate AGEs. Despite these observations, it is not known whether AGEs or RAGE signaling have a causal role in IVD degeneration. In this R21 application, we explore the AGEs- and RAGE-mediated events as novel disease mechanisms for IVD degeneration. Specifically, we will identify the role of AGEs in altering IVD structure and function and define the necessity of RAGE-signaling in AGEs-mediated degeneration. If our hypotheses are supported, this will provide the rationale for future research projects to address mechanisms and evaluate interventions in vivo. The IVD organ culture system allows precise modulation of the extracellular environment, and provides a high-throughput platform for screening degenerative pathways and therapeutic targets in the IVD. This approach allows proof-of-concept before moving to in vivo models and at the same time is suitable for use with transgenic models. Taken together, we believe that this approach is innovative and we will demonstrate its versatility by exploring a novel disease mechanism in IVD degeneration. These studies are aligned with the long-term goal of identifying novel, biochemically based therapeutic strategies to mitigate disc degeneration and associated LBP.
Degenerative disc disease afflicts over 80 million Americans a year, and bears significant health care costs. We aim to define the degenerative pathways leading to disc degeneration. The research work proposed here examines the role of Advanced Glycation End-products (AGEs), and the signaling of its receptor (RAGE) as a novel disease mechanism for the degeneration and inflammation of the intervertebral disc. Future work will examine therapeutics targeted at AGEs in translational models.
