BACKGROUND

Sepsis-induced acute lung injury (ALI) is a clinical condition with high morbidity and mortality, and impaired endothelial function is the main pathological characteristic. As a member of DNA demethylases, ten-eleven translocation protein 2 (TET2) is involved in a variety of biological processes. However, the role of TET2 in endothelial dysfunction of sepsis-induced ALI remains unclear.

METHODS

We used cecal ligation and puncture (CLP) to establish a sepsis-induced acute lung injury mouse model and screened out Tet2 from TET family proteins. The results suggested that Tet2 was obviously declined. We used lipopolysaccharide (LPS) to stimulate human pulmonary microvascular endothelial cells (HPMECs) as an in vitro model, and we found the expression of TET2 was also decreased. Then we used small interfering RNAs and adenovirus to knockdown or overexpress TET2 to investigate the effect of TET2 on the function of HPMECs. The changes in sepsis-induced ALI symptoms were also analyzed in Tet2-deficient mice generated by adeno-associated virus 6 (AAV6). Next, RNA sequencing and KEGG analysis were used to find the TET2-regulated downstream target genes and signaling pathways under LPS stimulation. Finally, the rescue experiments were performed to analyze the role of target genes and signaling pathways modulated by TET2 in LPS-treated HPMECs.

RESULTS

TET2 and 5-hmC levels were significantly decreased in both in vitro and in vivo models of sepsis-induced ALI. TET2 knockdown exacerbated the dysfunction and apoptosis of HPMECs induced by LPS. Conversely, TET2 overexpression significantly alleviated these dysfunctions and reduced apoptosis. Meanwhile, the lung injury of Tet2-deficient mice was aggravated by increased inflammation and apoptosis. RNA sequencing and subsequent experiments showed that TET2 overexpression could increase the expression of Integrin α10 (ITGA10) by reducing the methylation level of ITGA10 promoter. This, in turn, activated the PI3K-AKT signaling pathway. Knocking down ITGA10 weakened the beneficial effects of TET2 overexpression in LPS-stimulated endothelial cells.

CONCLUSIONS

In our study, we demonstrated that TET2 deficiency aggravates endothelial cell dysfunction and promotes acute lung injury by targeting ITGA10 via the PI3K-AKT pathway. These findings indicate that TET2 may be a promising therapeutic target for treating sepsis-induced ALI.