PARP-1 Inhibition Repressed Imbalance of Th17 and Treg Cells in Preterm Rats with Intrauterine Infection-Induced Acute Respiratory Distress Syndrome by Reducing the Expression Level of IL-6

Abstract

Background. Abundant reports have uncovered an imbalance of Treg and Th17 cells in pulmonary diseases. Hereon, we intend to explore the impact of PARP-1 on the imbalance of Th17/Treg and the potential mechanism in premature rats with acute respiratory distress syndrome (ARDS). Methods. Preterm ARDS infants and healthy term infants were enrolled in this investigation. To induce a rat model of ARDS, E.coli suspension was given to rats through two vaginal dilator-guided intramuscular injections. H&E staining was used to perform histopathological examination. Flow cytometry was employed to assess the proportion of Th17 or Treg cells accounted for CD4+ T cells. ELISA was applied to measure levels of IL-6, IL-17A, and IL-10 in the serum of ARDS patients. Moreover, the mRNA and protein expression levels of PARP-1, IL-6, IL-17A, and IL-10 were detected through qRT-PCR and western blotting. Results. An increased Th17/Treg ratio was observed in preterm infants and rats with ARDS. The PARP-1 expression level was raised in the lung tissues of ARDS rats, and PARP-1 downregulation alleviated E.coli-induced lung injury in preterm rats. Expression levels of PARP-1, IL-6, and IL-17A were raised, and the IL-10 level was reduced in the lung tissues of rats after E.coli treatment, which was all reversed by PARP-1 suppression. Importantly, the ratio of Th17/Treg differentiated from purified CD4+ T cells of the E.coli + PARP-1 inhibitor group was elevated by recombinant IL-6. Conclusion. PARP-1 downregulation repressed the imbalance of Th17 and Treg cells via reducing the expression level of IL-6, implying that PARP-1 may be a promising target for ARDS therapy.