RETRACTED ARTICLE: TN-2 modulates LPS-induced inflammatory response in human renal tubular epithelial cells by blocking TLR4-mediated NF-κB activation via MyD88- and TRIF-dependent mechanism

Clinopodium chinense Attenuates Palmitic Acid-Induced Vascular Endothelial Inflammation and Insulin Resistance through TLR4-Mediated NF- κ B and MAPK Pathways

Elevated palmitic acid (PA) levels are associated with the development of inflammation, insulin resistance (IR) and endothelial dysfunction. Clinopodium chinense (Benth.) O. Kuntze has been shown to lower blood glucose and attenuate high glucose-induced vascular endothelial cells injury. In the present study we investigated the effects of ethyl acetate extract of C. chinense (CCE) on PA-induced inflammation and IR in the vascular endothelium and its molecular mechanism. We found that CCE significantly inhibited PA-induced toll-like receptor 4 (TLR4) expression in human umbilical vein endothelial cells (HUVECs). Consequently, this led to the inhibition of the following downstream adapted proteins myeloid differentiation primary response gene 88, Toll/interleukin-1 receptor domain-containing adaptor-inducing interferon- β and TNF receptor-associated factor 6. Moreover, CCE inhibited the phosphorylation of Ikappa B kinase β , nuclear factor kappa-B (NF- κ B), c-Jun N-terminal kinase, extracellular regulated protein kinases, p38-mitogen-activated protein kinase (MAPK) and subsequently suppressed the release of tumor necrosis factor- α , interleukin-1 β (IL-1 β ) and IL-6. CCE also inhibited IRS-1 serine phosphorylation and ameliorated insulin-mediated tyrosine phosphorylation of IRS-1. Moreover, CCE restored serine/threonine kinase and endothelial nitric oxide synthase (eNOS) activation and thus increased insulin-mediated nitric oxide (NO) production in PA-treated HUVECs. This led to reverse insulin mediated endothelium-dependent relaxation, eNOS phosphorylation and NO production in PA-treated rat thoracic aortas. These results suggest that CCE can significantly inhibit the inflammatory response and alleviate impaired insulin signaling in the vascular endothelium by suppressing TLR4-mediated NF- κ B and MAPK pathways. Therefore, CCE can be considered as a potential therapeutic candidate for endothelial dysfunction associated with IR and diabetes.

Long non-coding RNA TUG1 protects renal tubular epithelial cells against injury induced by lipopolysaccharide via regulating microRNA-223

BACKGROUND

Lupus nephritis (LN) is a serious complication of systemic lupus erythematosus (SLE). Long non-coding RNA taurine upregulated gene 1 (lncRNA TUG1) exerted critical regulatory effects on inhibiting cell injury and inflammation. However, its role in LN is still unclear.

METHODS

HK-2 cells were treated with lipopolysaccharide (LPS) to simulate cell inflammatory injury. Cell viability and apoptosis, as well as pro-inflammatory factors expression were measured, respectively. Then, HK-2 cells were transfected with pEX-TUG1 or sh-TUG1 to explore the effects of TUG1 on LPS-induced cell injury. Potential binding effects between TUG1 and microRNA-223 (miR-223), as well as between miR-223 and Sirtuin 1 (Sirt1) were verified. miR-223 mimic or miR-223 inhibitor was transfected to assess the effects of miR-223 on cell injury. Finally, the roles of Sirt1 in LPS-induced HK-2 cell injury and activation of phosphatidylinositol 3-kinase/protein kinase 3 (PI3K/AKT) and nuclear factor kappa B (NF-κB) pathways were explored.

RESULTS

LPS administration inhibited HK-2 cell viability and proliferation, increased expression of pro-inflammatory factors, and promoted cell apoptosis. TUG1 overexpression protected HK-2 cells against LPS-induced injury via negatively regulating miR-223 expression. TUG1 suppression had opposite effects. Sirt1 was a direct target gene of miR-223 in HK-2 cells, which participated in the effects of miR-223 on HK-2 cells and was related with the activation of PI3K/AKT and NF-κB pathways.

CONCLUSION

TUG1 protected HK-2 cells against LPS-induced inflammatory injury by regulating miR-223 and Sirt1 expression, and then activating PI3K/AKT and inactivating NF-κB pathways. TUG1 might be a potential therapeutic target for LN treatment.

Activation of MTOR in pulmonary epithelium promotes LPS-induced acute lung injury

MTOR (mechanistic target of rapamycin [serine/threonine kinase]) plays a crucial role in many major cellular processes including metabolism, proliferation and macroautophagy/autophagy induction, and is also implicated in a growing number of proliferative and metabolic diseases. Both MTOR and autophagy have been suggested to be involved in lung disorders, however, little is known about the role of MTOR and autophagy in pulmonary epithelium in the context of acute lung injury (ALI). In the present study, we observed that lipopolysaccharide (LPS) stimulation induced MTOR phosphorylation and decreased the expression of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 β)-II, a hallmark of autophagy, in mouse lung epithelium and in human bronchial epithelial (HBE) cells. The activation of MTOR in HBE cells was mediated by TLR4 (toll-like receptor 4) signaling. Genetic knockdown of MTOR or overexpression of autophagy-related proteins significantly attenuated, whereas inhibition of autophagy further augmented, LPS-induced expression of IL6 (interleukin 6) and IL8, through NFKB signaling in HBE cells. Mice with specific knockdown of Mtor in bronchial or alveolar epithelial cells exhibited significantly attenuated airway inflammation, barrier disruption, and lung edema, and displayed prolonged survival in response to LPS exposure. Taken together, our results demonstrate that activation of MTOR in the epithelium promotes LPS-induced ALI, likely through downregulation of autophagy and the subsequent activation of NFKB. Thus, inhibition of MTOR in pulmonary epithelial cells may represent a novel therapeutic strategy for preventing ALI induced by certain bacteria.