The protective role of YTHDF1-knock down macrophages on the immune paralysis of severe sepsis rats with ECMO

OBJECTIVE

To examine the role of YTHDF1 knock-down macrophages on the immunity of severe sepsis rats with ECMO.

METHODS

15 SD rats were randomly allocated into 3 groups: mild sepsis (I), severe sepsis with ECMO (II), and YTHDF1 knock-down macrophages treatment groups (III). Blood biochemical indexes, different immune factors and brain changes were detected by RT-PCR, ELISA, ELISPOT and HE staining. Isolated macrophages subtypes and signal proteins were detected by flow cytometry, western blot and m6A RNA methylation test.

RESULTS

The levels of HMGB1, RAGE, YTHDF1 and IL-17 in peripheral blood were significantly higher (p < 0.01), while the level of CXCL9 and TNF-α, and LPS-specific CD8+CTL function were significantly decreased in group II compared with group I (p < 0.01). The ratio of CD63+ macrophages (p < 0.05) and CD64+ macrophages (p< 0.05) decreased and the level of elastase (p < 0.01) and CCR2highCX3CR1low/CCR2lowCX3CR1high (p < 0.01) of macrophages increased in group II. The above were consistent with the severity of biochemical indicators, the increasing endothelial injury factor (Ang2/Ang1), lower endothelial protective factor (sTie2), severer brain injury in group II. After YTHDF1 knock-down macrophages treatment, the above indexes' changes were opposite when Group III versus Group II through the down-regulation of m6A RNA methylation of JAK2/STAT3 (p < 0.01) and protein expression of PJAK2/PSTAT3 (p < 0.05) in isolated macrophages.

CONCLUSIONS

YTHDF1 knock-down macrophages improved the immune paralysis of macrophages, Th1/Th17 and CTL and reduced the entry of macrophages into the brain to cause endothelial damage of severe sepsis rats with ECMO through the inhibition of HMGB1/RAGE and YTHDF1, m6A RNA methylation of JAK2/STAT3 and PJAK2/PSTAT3 proteins expression in macrophages.