Knockdown of CCR3 gene inhibits Proliferation, migration and degranulation of eosinophils in mice by downregulating the PI3K/Akt pathway.

• CCR3-/- mice were constructed by NBRI using the Cre-LoxP system to knock out CCR3 target genes in bone marrow cells. • The proliferative activity of EOS, expression of EPO and p-Akt in the WT EOS group were higher than those in CCR3-/- EOS group (all P < 0.05). • The number of migrated cells in the WT EOS group were higher than those in CCR3-/- EOS group (P < 0.05). • After adding eotaxin, the WT EOS group was higher than the other three groups (all P < 0.05). • CCR3-/- inhibited EOS's proliferation, migration and degranulation by downregulating PI3K/Akt pathway. This study aimed to investigate the effects of CCR3 knockdown (CCR3-/-) on the proliferation, migration, and degranulation of the bone marrow eosinophils (EOS) in mice. Bone marrow cells from wild-type mice (WT) were harvested for primary culture and differentiated into mature EOS, which were then randomly divided into the control, 740Y-P, and LY294002 group. The effects of different concentrations of LY294002 (PI3K inhibitor) and 740Y-P (PI3K agonist) on the proliferation viability of EOS, expressions of EPO, Akt, and p-Akt proteins, and migration changes of EOS were detected. CCR3-/- mice were identified. Then, bone marrow cells of WT and CCR3-/- mice were differentiated into mature EOS and grouped into WT EOS, WT EOS + eotaxin (100 ng/mL), CCR3-/- EOS, and CCR3-/- EOS + eotaxin (100 ng/mL) group. The changes in EOS proliferation, migration, as well as expressions of EPO, Akt, and p-Akt proteins were detected. The number of migrated cells (P < 0.01) and expression of EPO (p < 0.05) in the 740Y-P group were higher than those in the control group, while opposite trends were observed for the LY294002 group. Expression levels of p-Akt and Akt in the LY294002 group were significantly lower than in the control group (all P < 0.01). Also, the expression of p-Akt in the 740Y-P group was significantly higher than that in the control group (p < 0.05). The proliferative activity of EOS, expression of EPO and p-Akt, and the number of migrated cells in the WT EOS group were higher than those in CCR3-/- EOS group (all P < 0.05). After adding eotaxin, the WT EOS group was higher than the other three groups (all P < 0.05). Mechanistically, CCR3-/- inhibited EOS's proliferation, migration, and degranulation by downregulating PI3K/Akt pathway. This data suggests that the knockout of the CCR3 gene in bone marrow cells may inhibit the function of EOS by downregulating the PI3K/Akt pathway, thereby affecting AR; thus, the CCR3 gene may be a target gene for AR therapy. [ABSTRACT FROM AUTHOR]