circDCBLD2 regulates the Th1/Th2 immune balance via the miR-26a-5p/PTEN axisOA

Asthma is a prevalent chronic respiratory disease in children.Recently,adjusting the Th1/Th2 imbalance has become a significant focus in asthma immunotherapy.The present study aims to investigate the roles and mechanisms of circDCBLD2 in maintaining the Th1/Th2 immune balance.CircDCBLD2 is downregulated in CD4^(+)T cells from asthmatic patients and in CD4^(+)T cells from an OVA-induced asthmatic mouse model.Additionally,circDCBLD2 levels are significantly decreased in the PBMCs of asthmatic mice.The expression of circDCBLD2 is positively correlated with the Th1 cytokines IFN-γand IL-2 but negatively correlated with the Th2 cytokines IL-4 and IL-13.Flow cytometry and ELISA analyses demonstrate that circDCBLD2 overexpression increases the proportion of Th1 cells(CD4^(+)IFN-γ^(+))and the levels of Th1 cytokines while decreasing the proportion of Th2 cells(CD4^(+)IL-4^(+))and the levels of Th2 cytokines.Furthermore,circDCBLD2 overexpression alleviates the asthma phenotype in OVAinduced mice,reduces the infiltration of inflammatory cells in the lungs,and corrects the Th1/Th2 imbalance.Mechanistically,circDCBLD2 is found to target miR-26a-5p.Rescue experiments indicate that circDCBLD2 regulates the Th1/Th2 immune balance by targeting miR-26a-5p.Additionally,PTEN has been identified as a direct target of miR-26a-5p.The overexpression of PTEN partially reverses the effects of miR-26a-5p on the Th1/Th2 immune balance.These findings indicate that circDCBLD2 increases the proportion of Th1 cells and decreases the proportion of Th2 cells via the miR-26a-5p/PTEN axis,providing a promising target for asthma treatment.