RESUMEN
Critically ill patients have increased susceptibility to translocation of gut bacteria. However, the mechanisms are complicated and remain unclear, and the aim of this study was to explore these mechanisms. Rats exposed to different levels of shock were orally administrated with bioluminescent Citrobacter. We found that severe shock caused an increase in bacterial translocation to the visceral organs, such as liver, spleen and blood, compared with mild shock. Surprisingly, bacterial translocation to mesenteric lymph node (MLN) was unchanged between the two shock groups. Various methods, including flow cytometry, a co-culture model and western blots, were used to evaluate MLN-associated immune function. Specifically, we focused on mesenteric lymph node dendritic cells (MLN-DCs), the critical antigen presenting cells involved in the construction of the immune barrier in MLN. We also found that severe shock impaired the phenotypic maturation of MLN-DCs and induced a tolerogenic phenotype. Furthermore, co-culture assays of DCs with naive CD4+ T cells showed that DCs subject to severe shock were more inclined to polarize native CD4+ T cells into Th2 and Treg cells. This study successfully reproduced the clinical phenomenon of severe shock resulting in increased bacterial translocation to extraintestinal tissues, and this may be related to the compromised immune barrier function of MLN, as maturation and function of MLN-DC's were badly impaired.
RESUMEN
AMP-activated protein kinase family member 5 (ARK5) overexpression has been reported in many human cancers, and ARK5 is associated with poor prognosis in hepatocellular carcinoma (HCC). However, whether ARK5 is involved in HCC chemoresistance is unclear. The present study aimed to investigate the role of ARK5 in HCC chemoresistance and the underlying mechanism. In this study, we found that SNU387 and SNU449 HCC cell lines overexpressing ARK5 displayed low doxorubicin sensitivity compared to Huh7 and Hep3B HCC cell lines with ARK5 low-expression. And knockdown of ARK5 increased the doxorubicin sensitivity in all HCC cell lines in the manner of inhibiting cell proliferation. Western blotting and immunofluorescence both showed that ARK5 knockdown upregulated E-cadherin and downregulated vimentin, which was consistent with the knockdown of TWIST, indicating ARK5 was involved in epithelial-mesenchymal transition (EMT). Moreover, suppressing ARK5 by siRNA restored E-cadherin and vimentin expression induced by doxorubicin treatment or hypoxia culture. Our results indicated ARK5 confers doxorubicin resistance in HCC via inducing EMT.