Effect Of Granulocyte Colony-Stimulating Factor Mobilization On The Expression Of Th1/Th2 Chemokines and Their Receptors
Authors: Xuan Li , Wu Xiuli , Jin Zhenyi , Wang Xu , Dai Min , Zhang Yu , Li Yangqiu , Liu Qifa 
Published: October 2019

Background
Granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood stem cell (PBSC) has been used more frequently than bone marrow as the source of stem cells in allogeneic hematopoietic stem cell transplantation (allo-HSCT). Although it contains more mature T cells, neither the incidence nor the severity of acute graft-versus-host disease (aGVHD) is higher compared with bone marrow transplantation. This might be due to the immunoregulatory effects of G-CSF on adaptive immunity, including that G-CSF directly modulated via its receptor on T cells or indirectly modulated T cell immune responses via effector cells and cytokines. However, these mechanisms are not fully understood, and whether G-CSF could influence the expression of Th1/Th2 chemokines and their receptors remains unknown. The aim of this study is to investigate the effect of G-CSF mobilization on the expression of Th1/Th2 chemokines and their receptors.

Methods
The expression levels of Th1 chemokines (CXCL9, CXCL10, and CXCL11), Th2 chemokines (CCL17, CCL22) and their receptors CXCR3 and CCR4 were analyzed in peripheral blood mononuclear cells (PBMCs) from 25 donors before and after G-CSF mobilization, using real-time RT-PCR with SYBR Green±staining. The β2-microglobulin gene (β2-MG) was used as an endogenous reference, and the relative mRNA expression level of each gene was evaluated by the 2-ΔC t×100% method.

Results
The median expression level of CXCR3 was similar before and after G-CSF mobilization (0.1426% and 0.1109%) (P=0.278), while the expression level of CCR4 after G-CSF mobilization (0.0985%) was significantly lower than that before mobilization (0.1415%) (P=0.039). The median expression levels of CXCL9, CXCL10, and CXCL11 genes before mobilization (0.0048%, 0.0576% and 0.0079%) were not significantly different from that after G-CSF mobilization (0.0143%, 0.0666% and 0.0088%)(P=0.086, P=0.535 and P=0.680). The median expression levels of CCL17 and CCL22 were also similar before and after G-CSF mobilization (P=0.155, P=0.476). The expression pattern of three Th1 chemokines before mobilization was CXCL10> CXCL11> CXCL9, whereas it changed to CXCL10> CXCL9> CXCL11 after mobilization. The expression pattern of two Th2 chemokines before mobilization was CCL17> CCL22, whereas it changed to CCL22> CCL17 after mobilization. The relative expression levels of CXCL10 and CXCL11 genes before mobilization both showed a positive correlation to that after mobilization (P<0.001, r=0.760; P=0.024, r=0.470). Before mobilization, signiﬁcant positive correlation was observed between the expression levels of CXCL9 and CXCL10, CXCL11 and CXCR3, CXCL11 and CCL22, CXCR3 and CCL22 (P<0.001, r=0.902; P=0.003, r=0.584; P=0.022, r=0.473; P<0.001, r=0.674, respectively). After G-CSF mobilization, signiﬁcant positive correlation was observed between the expression levels of CXCL9 and CCL22, CXCL10 and CXCL11, CXCR3 and CCR4, CXCR3 and CCL22, CXCR3 and CCL17, CCL22 and CCL17 (P=0.001, r=0.653; P=0.001, r=0.665; P=0.002, r=0.602; P=0.028, r=0.458; P<0.001, r=0.738; P=0.044, r=0.424, respectively).

Conclusions
Our findings suggest that G-CSF mobilization might mainly influence the expression level of CCR4 genes in Th1/Th2 chemokines and their receptors. The expression patterns of Th1 chemokines and Th2 chemokines might both change after G-CSF mobilization.

Disclosures:
Li: This work was supported by Grants from National Natural Science Foundation of China (30871091 and 91129720), the Collaborated grant for HK-Macao-TW of Ministry of Science and Technology (2012DFH30060), the Guangdong Science & Technology Project (2012B0506: Research Funding. Liu:It was supported by 863 Program (No. 2011AA020105).: Research Funding; It was supported by National Public Health Grand Research Foundation (Grant No. 201202017), National Natural Science Foundation of China (Grant No.81000231, No.81270647).: Research Funding; It was supported by Science and Technology Program of Guangzhou of China (11A72121174).: Research Funding.