RESUMO
Myeloid-derived suppressor cells (MDSCs) are pathologically activated and relatively immature myeloid cells that have been implicated in the immunological regulation of many pathologic conditions. Phenotypically and morphologically, MDSCs are similar to neutrophils (PMN-MDSCs) and monocytes (M-MDSCs). However, they have potent suppressive activity and distinct gene expression profiles and biochemical characteristics. No or very few MDSCs are observed in steady-state physiological conditions. Therefore, until recently, accumulation of MDSCs was considered a consequence of pathological processes or pregnancy. Here, we report that MDSCs with a potent ability to suppress T cells are present during the first weeks of life in mice and humans. MDSC suppressive activity was triggered by lactoferrin and mediated by nitric oxide, PGE2, and S100A9 and S100A8 proteins. MDSCs from newborns had a transcriptome similar to that of tumor MDSCs, but with strong upregulation of an antimicrobial gene network, and had potent antibacterial activity. MDSCs played a critical role in control of experimental necrotizing enterocolitis (NEC) in newborn mice. MDSCs in infants with very low weight, who are prone to NEC, had lower MDSC levels and suppressive activity than did infants with normal weight. Thus, the transitory presence of MDSCs may be critical for regulation of inflammation in newborns.
Assuntos
Enterocolite Necrosante/metabolismo , Recém-Nascido de muito Baixo Peso/metabolismo , Inflamação/genética , Células Supressoras Mieloides/metabolismo , Animais , Animais Recém-Nascidos , Calgranulina A/genética , Calgranulina B/genética , Dinoprostona/genética , Enterocolite Necrosante/genética , Enterocolite Necrosante/patologia , Regulação da Expressão Gênica/genética , Humanos , Inflamação/metabolismo , Inflamação/patologia , Lactoferrina/genética , Lactoferrina/metabolismo , Camundongos , Células Supressoras Mieloides/patologia , Óxido Nítrico/genética , Óxido Nítrico/metabolismoRESUMO
AIM: To explore the role and potential mechanism of miR-30b regulation of autophagy in hepatic ischemia-reperfusion injury (IRI). METHODS: An animal model of hepatic IRI was generated in C57BL/6 mice. For in vitro studies, AML12 cells were immersed in mineral oil for 1 h and then cultured in complete Dulbecco's Modified Eagle's Medium (DMEM)/F12 to simulate IRI. Mice and cells were transfected with miR-30b agomir/mimics or antagomir/inhibitor to examine the effect of miR-30b on autophagy to promote hepatic IRI. The expression of miR-30b was measured by real-time polymerase chain reaction. Apoptotic cells were detected by terminal uridine nick-end labeling (TUNEL) staining, and cell viability was detected by methylthiazole tetrazolium assay. The expression of light chain 3, autophagy-related gene (Atg)12, Atg5, P62, and caspase-3 were detected by western blotting analysis. RESULTS: miR-30b levels were significantly downregulated after hepatic IRI, and the numbers of autophagosomes were increased in response to IRI both in vivo and in vitro. These findings demonstrate that low levels of miR-30b could promote hepatic IRI. Furthermore, we found that miR-30b interacted with Atg12-Atg5 conjugate by binding to Atg12. Overexpression of miR-30b diminished Atg12 and Atg12-Atg5 conjugate levels, which promoted autophagy in response to IR. In contrast, downregulation of miR-30b was associated with increased Atg12-Atg5 conjugate levels and increased autophagy. CONCLUSION: miR-30b inhibited autophagy to alleviate hepatic ischemia-reperfusion injury via decreasing the Atg12-Atg5 conjugate.
