Mechano-driven Immune Crosstalk During Joint Degeneration

Career Development and Mentoring: My long-term career goal is to establish an independent laboratory
evaluating the inflammatory environment associated with highly prevalent musculoskeletal diseases, to
ultimately identify tissue specific therapeutic modalities for regulating inflammation and promoting repair. My
prior graduate training included 5-years of focused basic science research where I developed expertise in small
animal models of disc degeneration (physical injury & genetically induced), macrophage biology
(mechanotransduction, activation, functionality), joint histopathology and image analysis, and biomechanics.
This experience in musculoskeletal research has provided me with a strong foundation for success as a
postdoctoral fellow. By pursuing the Research Plan described in this proposal, I will further my training in more
sophisticated models of musculoskeletal disease (knee OA), high dimensional immunophenotyping, high-
resolution imaging, and murine pain-behavior analysis. With direct support from my mentors, Dr. Carla Scanzello
MD, PhD and Dr. Robert Mauck PhD, and collaborators, Dr. Karen Hasty, PhD, Dr. De’Broski Herbert, PhD, and
Dr. Tristan Maerz, PhD, I will receive mentorship in mechanical overloading models, musculoskeletal
mechanobiology, and immunology, in addition to mentorship in career development and scientific collaboration.
Research Plan: Injury and overuse introduce aberrant mechanical strains across the knee joint, inducing
cellular stresses and a degenerative biological environment thought to contribute to OA. Another biological
characteristic of disease pathology, synovial inflammation has been strongly associated with progression of OA
(e.g., joint space narrowing and cartilage damage) and pain. When synovitis develops, the synovium acts as a
reservoir of local inflammatory bi-products and infiltrating immune cells, of which macrophages are found in the
highest frequency. To demonstrate how mechanically activated cartilage drives synovial inflammation and
subsequent macrophage activation during OA progression we will utilize a joint overloading model to induce OA
with purely mechanically driven inflammation in the murine knee. Combining methods of high dimensional
transcriptional (single cell sequencing) and spatial proteomic analysis (imaging mass cytometry) we aim to
identify and localize inflammatory cell populations throughout loaded joint tissues. We will first compare
differential effects of singular vs. repetitive loading on cartilage and synovial inflammation and combine with
histopathology and pain behavior evaluations to identify associations with inflammation and painful OA
pathology. We will next develop a co-culture model from previously in-vivo loaded tissue explants (synovium and
cartilage), to test the specific hypotheses related to loaded cartilage and synovial driven inflammatory signaling.
We will utilize this co-culture model to identify differential tissue specific (cartilage, synovium) effects of loading
mediated inflammatory signaling specifically on macrophage activation via functional assays (secretome,
phagocytosis, migration, bulk RNA sequencing). Completion of the proposed work will further the understanding
of how mechanobiology contributes to joint degeneration via multi joint tissue inflammatory signaling and immune
cell activation, ultimately providing new avenues of disease mediating therapeutic targets. Results of this work
will provide important insights into disease mechanisms to drive novel therapeutic development and thus will
greatly benefit the large population of Veterans and active-duty personnel affected by OA. The proposed
research and mentoring plans, collaborative environment, and facilities at the Philadelphia VA Medical Center
and the University of Pennsylvania will position me to accomplish my goals of becoming a leading VA-based
independent scientist in the fields of musculoskeletal mechanobiology and immunology.

Grant Number: 1IK1RX005014-01A2
NIH Institute/Center: VA
Principal Investigator: Kevin Burt