NORA Construction Sector Strategic Goals
9270075 - Musculoskeletal Disorders and Innate Immune System
Principal Investigator (PI)
Primary Goal Addressed
Secondary Goal Addressed
Attributed to Construction
Work-related musculoskeletal disorders (MSDs) represent a variety of disorders which are associated with chronic or acute inflammatory responses involved in both tissue degeneration and regeneration. Our current effort is directed to develop a novel approach to improve healing and return to function after severe traumatic muscle injury. The US Army Institute of Surgical Research expressed a high interest and support of this work. The project will help NIOSH to meet its strategic goal on construction and manufacturing sectors as well as musculoskeletal disorders cross sector to reduce the incidence and severity of work-related musculoskeletal disorders among workers in the U.S. Identifying specific molecular steps involved in regulation of tissue injury and repair will provide a basis for successful diagnosis, treatment, and prevention of musculoskeletal diseases resulting in substantial cost savings and improved health for thousands of workers.
Muscle injuries occur through a variety of mechanisms, including direct trauma, (laceration; contusions; strains) and indirect causes (ischemia; neurological dysfunction). The major events are: membrane destruction, influx of calcium, activation of the intrinsic proteases and the innate immune system. The healing process is a delicate balance between muscle regeneration and fibrogenesis. The complete recovery of muscle tissue and function are compromised by the scar formation with tendency for muscle injury to recur. The manipulation of the innate immune system and specifically pharmacological manipulation of macrophage receptors to affect the pro-myogenic and pro-fibrotic actions of cytokines, chemokines, and growth factors is a highly promising approach for improving of healing and function of injured muscle.
We propose to accomplish the following five tasks:
Task #1: Focusing on pro-fibrotic and pro-myogenic mediators, determine using DNA microarray technology the gene expression profiles for two models of traumatic muscle injury, one in which regeneration of the muscle is complete and one in which regeneration is impaired.
Task #1a: For the two models, determine the level of gene expression for all genes on the cytokine-, growth factor-, and Toll-like receptor-targeted DNA microarrays.
Task #1b: Compare the gene expression profiles for the two models of injury and identify genes that are differentially expressed between the two models.
Task #1c: From the differentially-expressed genes, identify candidate genes for categorization as pro-fibrotic or pro-myogenic mediators.
Task #2: Validate the findings of Task #1. For the candidate “pro-fibrotic and pro-myogenic mediator” genes determined in Task #1
Task #2a: Determine for the two models of injury the levels of gene and protein expression for each candidate gene using quantitative RT-PCR and immunoblotting techniques, respectively.
Task #2b: For each of the previously unstudied candidate genes, determine the cellular localization of its gene product. Determine if the localization is consistent with the gene’s known or proposed cellular function.
Task #3: Using macrophage cell cultures, identify immunotherapies (i.e., macrophage modulators) targeting Toll-like receptors that enhance the expression and secretion of mediators which could stimulate muscle regeneration. These assessments will make use of the panel of differentially-expressed pro-fibrotic and pro-myogenic genes determined from Tasks #1 and 2.
Task #4: For immunotherapies found to be promising in Task #3, determine if local application of these immunotherapies to traumatically-injured muscle normalizes or enhances the relative expression of pro-myogenic to pro-fibrotic genes
Task #4a: For the model of traumatic muscle injury in which regeneration is impaired, determine if after immunotherapy application the relative expression of pro-myogenic to pro-fibrotic genes becomes like that for the model of muscle injury in which regeneration is complete.
Task #4b: For the model of traumatic muscle injury in which regeneration is complete, determine if after immunotherapy application the relative expression of pro-myogenic to pro-fibrotic genes is shifted towards one favoring an enhanced or accelerated myogenesis.
Task #5: For the three immunotherapies found to be most effective in Task #4, determine if local application of these immunotherapies to traumatically-injured muscle results in an accelerated, complete recovery as assessed by restoration of morphology and function.
•To identify series of genes which are related to skeletal muscle injury/repair mechanisms.
•To evaluate whether modulation of selected inflammatory proteins and mechanisms alters the repair process in injured muscle.
•To evaluate the role of inflammation in occupational-related musculoskeletal injuries and to provide scientific basis for optimal identification and treatment of these disorders.
•To define the macrophage-secreted mediators which can regulate the balance between regeneration and scarring of injured muscle tissue
•To identify immunotherapies which have a potential to induce and accelerate regeneration of injured muscle. The immunotherapeutic application for enhancing restorative injury repair might be a novel approach with considerable potential impact.
•Multiple peer review publications.
•Presentations at national and international scientific meetings.
•Citations of our findings in scientific publications and documents.