Modulation of the HGF/c-Met Axis Impacts Prolonged Hematopoietic Progenitor Mobilization Following Trauma and Chronic Stress

Abstract

Background: Trauma and hemorrhagic shock trigger mobilization of hematopoietic progenitor cells (HPC) from bone marrow to peripheral blood. Hepatocyte growth factor (HGF), tyrosineprotein kinase Met (c-Met), matrix metallopeptidase 9 (MMP-9), and corticosterone regulate this mobilization process. We hypothesized that beta-blockade with propranolol and sympathetic outflow inhibition with clonidine following trauma and chronic stress would decrease hematopoietic progenitor cell mobilization.Methods: Sprague-Dawley rats were randomized to undergo three models of injury and stress: lung contusion (LC), LC plus hemorrhagic shock (LCHS), or LCHS plus chronic restraint stress for 2h daily (LCHS/CS). Propranolol and clonidine were administered by daily intraperitoneal injection until sacrifice on day seven. Bone marrow HGF, c-Met, and MMP-9 were measured by real-time PCR. Plasma corticosterone was measured by ELISA. %HPC in peripheral blood was measured by flow cytometry.Results: Propranolol and clonidine significantly decreased bone marrow MMP-9 expression, plasma corticosterone levels, and HPC mobilization, and significantly increased hemoglobin levels. HPC mobilization was greatest following LCHS/CS (5.4±1.8) and was significantly decreased by propranolol (2.2±0.9, p <0.001) and clonidine (1.7±0.5, p <0.001). Hemoglobin (g/dL) was lowest following LCHS/CS (12.3±1.2) and was significantly increased by propranolol (13.7±0.4, p =0.022) and clonidine (14.1±1.1, p <0.001). Conclusions:Severe injury was associated with increased bone marrow HGF, c-Met, and MMP-9, circulating corticosterone, HPC mobilization, and persistent anemia. Attenuating the neuroendocrine response to injury and stress with propranolol and clonidine reduced MMP-9 expression, corticosterone levels, HPC mobilization, and the degree of anemia.

Adrenergic Modulation of Erythropoiesis After Trauma

“…Factors such as plasma corticosterone, HGF, MMP-9, c-Met, and G-CSF all play roles in HPC mobilization as previously described. Among rats subjected to LCHS with chronic restraint stress, plasma corticosterone levels were significantly elevated compared to controls; these levels were subsequently significantly decreased by 125 ng/ml when administered daily intraperitoneal clonidine compared to untreated counterparts ( Loftus et al, 2020 ). In a rodent model of LC, LCHS, or LCHS and chronic stress with or without clonidine administration, rodents who underwent LC or LCHS + CS showed significantly elevated levels of bone marrow HGF and MMP-9 compared to controls ( Loftus et al, 2020 ).…”

“…Among rats subjected to LCHS with chronic restraint stress, plasma corticosterone levels were significantly elevated compared to controls; these levels were subsequently significantly decreased by 125 ng/ml when administered daily intraperitoneal clonidine compared to untreated counterparts ( Loftus et al, 2020 ). In a rodent model of LC, LCHS, or LCHS and chronic stress with or without clonidine administration, rodents who underwent LC or LCHS + CS showed significantly elevated levels of bone marrow HGF and MMP-9 compared to controls ( Loftus et al, 2020 ). Clonidine administration resulted in significant decline in bone marrow MMP-9 and c-Met compared to untreated rats in LCHS + CS and LC, respectively ( Loftus et al, 2020 ).…”

“…This study also found significantly decreased growth of CFU-E, BFU-E, and CFU-GEMM in bone marrow-derived cells from all groups subjected to stress and/or trauma, but that such reductions could be prevented with clonidine administration, showing significantly increased levels of CFU-E, BFU-E, and CFU-GEMM when compared to untreated groups ( Alamo et al, 2017b ). Another study of LCHS with chronic stress also demonstrated an increase in peripheral HPC which was significantly decreased after clonidine administration ( Loftus et al, 2020 ). Factors such as plasma corticosterone, HGF, MMP-9, c-Met, and G-CSF all play roles in HPC mobilization as previously described.…”

“…These models have been validated to effectively influencing a variety of factors involved in erythropoiesis as will be discussed in the following sections. The models of LC, LCHS and LCHS + CS affect expression of hematopoietic cytokines, HMGB1, SCF, Bcl-xL; urine norepinephrine; hemoglobin; plasma G-CSF; HPC mobilization; plasma corticosterone; bone marrow cellularity; and erythroid progenitor cell growth ( Alamo et al, 2017b ; Loftus et al, 2019 ; Loftus et al, 2020 ).…”

“…In a rodent model of LC, LCHS, or LCHS and chronic stress with or without clonidine administration, rodents who underwent LC or LCHS + CS showed significantly elevated levels of bone marrow HGF and MMP-9 compared to controls ( Loftus et al, 2020 ). Clonidine administration resulted in significant decline in bone marrow MMP-9 and c-Met compared to untreated rats in LCHS + CS and LC, respectively ( Loftus et al, 2020 ). Levels of bone marrow HGF were not significantly different in rats treated with clonidine compared to untreated ( Loftus et al, 2020 ).…”