Chemokine Profiling in Patients with Graft Versus Host Disease (GVHD) Following Allogeneic Blood Stem Cell Transplantation.

Development of GVHD following allogeneic blood stem cell or bone marrow transplantation (BMT) is dependent on the immunogenetic disparity between donor and host, subsequent alloactivation and the inflammatory reaction occurring secondary to conditioning regimen-induced tissue damage. The inflammatory response occurring early following conditioning therapy is thought to be particularly crucial for the subsequent development of GVHD as it occurs in response to tissue damage and is amplified by the alloresponse. Chemokines are predominantly small molecules (8–14 kd) that bind to a family of heterotrimeric G-protein-coupled receptors with a seven-transmembrane-spanning serpentine structure and play an important role in leukocyte trafficking and are thought to be involved in tissue infiltration during GVHD. Reports from several investigators using murine model have demonstrated the relevance of distinct chemokines in the pathogenesis of GVHD. Furthermore, we have recently demonstrated that conditioning intensity and genetic host factors influence the tissue and systemic expression of chemokines during the early course of GVHD in rodent BMT models. However, the pathobiologic relevance of chemokines expression at later time points during GVHD and in human GVHD is so far unclear.

Using luminex multiplex assays we studied the sera of patients, who had undergone peripheral blood stem transplantation from an allogeneic HLA matched sibling or matched unrelated donor in order to determine the chemokine profiles during GVHD. In addition to the most relevant cytokines/cytokine receptors (IL-1a, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IFN-a, IFN-g, GM-CSF, IL-12 (p40), IL-13, IL-15, IL17, TNF-alpha, TNF-RI, TNF-RII, DR5, FGF-b, VEGF, HGF, IL-1Ra, sIL-2R and sIL-6R), we analyzed the serum expression of CCL2, CCL3, CCL4, CCL5, CCL11, CXCL9, and CXCL10. Patients with acute GVHD of the gut (n=8), patients without GVHD (n = 4) and patients with chronic GVHD (n=4) were studied. Patients with acute/chronic GVHD had significantly elevated levels of CCL3 (90 pg/ml vs. 58 pg/ml, p= 0.004) and CCL11 (167pg/ml vs. 93pg/ml) compared to controls patients without GVHD. Patients with acute GVHD of the gut had also markedly elevated CXCL10, CCL4 levels although not reaching statistical significance. In addition, patients with acute or chronic GVHD were found to have significantly elevated serum levels of HGF, IL-1Ra, and TNF-RI.

In conclusion we are able to demonstrate that CCL3 appears to be the most prominent chemokine to be elevated in the serum of patients with a/cGVHD supporting results obtained in preclinical BMT models. Given the complex and frequently contradictory preclinical results, further studies are warranted to confirm our findings in larger cohorts of patients and to delineate whether targeting CCL3 or one of its receptor (CCR1 or CCR5) might prove beneficial for the treatment of GVHD.