Addressing Collagen Mediated Protection of Systemic Amyloid Fibrils - Project Abstract The systemic amyloidoses are a family of non-cerebral, protein misfolding disorders in which amyloidogenic precursor proteins aggregate into well-ordered amyloid fibrils that deposit in the extracellular space of organs and tissues. Progressive fibril deposition leads to progressive organ dysfunction, severe morbidity, and death. Current treatment modalities focus on inhibiting the synthesis of amyloidogenic precursor proteins resulting in prolonged patient survival but are not curative. Unfortunately, these therapeutic approaches are susceptible to refractory amyloidogenic protein synthesis and do not address the removal of preexisting protein deposits which cause the organ dysfunction and morbidity. It is well established that amyloid burden inversely correlates with disease outcomes; therefore, curative interventions will likely involve combinatorial approaches targeting both precursor protein production and the removal of amyloid deposits. Several immunotherapeutic approaches (i.e., antibody-based therapeutics) have been designed to stimulate immune-mediated clearance of amyloid, but these therapies have yet to demonstrate significant clinical benefit. However, such therapeutics would not be necessary if the body was capable of naturally removing amyloid deposits. Here, we take a step back to address the underlying question as to why amyloid fibrils are not typically removed by the body. Recently, we demonstrated that collagen-1 is capable of inhibiting macrophage uptake of amyloid and that in patients diagnosed with various types of amyloidosis, collagen-1 colocalizes with amyloid fibrils in vivo. Together, these data and additional preliminary data support our hypothesis that amyloid-associated collagen prevents recognition of tissue amyloid by the immune system thereby hindering amyloid clearance. We propose three specific aims to investigate the process of collagen-mediated amyloid protection and assess potential therapeutic strategies. Preliminary data indicate that blocking the CD36 scavenger receptor inhibits macrophage uptake of amyloid akin to collagen mediated inhibition. Therefore, in Aim 1 we will interrogate the CD36-amyloid-collagen relationship through cellular knockout approaches. We will also determine if other amyloid associated proteins can limit macrophage uptake of amyloid. Next in Aims 2 and 3 we propose two distinct approaches to locally degrade collagen within amyloid masses. In Aim 2 we will deliver matrix metalloproteinases to amyloidogenic regions by coupling MMP-1 and/or MMP-9 to our amyloid binding peptides. In Aim 3, we seek to immunoform amyloidogenic regions and stimulate cells within the amyloid environment to locally express collagen degrading enzymes and immune activating proteins. We will fuse proteins proven to induce MMP expression and immune activation (e.g., C3a, C5a, or Substance P) to the p5R amyloid binding peptide. We will determine the ability of both peptide fusion strategies to induce collagen degradation within amyloid lesions and immune activation. Overall, our goal is to interrogate how collagen limits immune cell functions and enhance amyloid clearance by locally degrading amyloid-associated collagen.
