Immunomodulatory effect of circulating bone marrow progenitors as a possible mechanism of neuroprotection in traumatic brain injury
We have previously shown that acute traumatic brain injury (TBI) is accompanied by increased level of circulating bone marrow progenitors, and favorable outcome is associated with early mobilization of CD34+CD45+ hematopoietic progenitor cells (HP). The present study was aimed at investigating whether patients with early HP mobilization differed from those with mobilization failure by systemic inflammatory reaction and immune parameters. The TBI patients were characterized by increased levels of serum C-reactive protein (CRP), IL-1β, IL-6, IL-8, MCP-1, G-CSF and IL-1ra indicative for presence of systemic inflammatory response. Importantly, patients with lacking mobilization of early HPs were shown to have significantly higher serum levels of CRP, MCP-1, MIP-1β, and G-CSF and a lower level of VEGF. In addition, patients with lack of early HP mobilization differed by significantly lower absolute number of lymphocytes, CD3+ T cells, CD4+ T cells, CD16+ NK cells and proliferative response of mononuclear cells to stimulation with ConA as well as by 4-fold higher rate of infectious complications compared with the opposite group. These data suggest that correlation of early mobilization of CD34+CD45+ cells with a favorable outcome in TBI patients may be partially mediated by anti-inflammatory and immunomodulatory effects of circulating bone marrow progenitors.