RESUMO
Polyphyllin Ⅰ(PPⅠ)and polyphyllin Ⅱ(PⅡ)are the main active substances in the Paris polyphylla.However,liver toxicity of these compounds has impeded their clinical application and the potential hepatotoxicity mechanisms remain to be elucidated.In this work,we found that PPⅠ and PⅡ exposure could induce significant hepatotoxicity in human liver cell line L-02 and zebrafish in a dose-dependent manner.The results of the proteomic analysis in L-02 cells and transcriptome in zebrafish indicated that the hepa-totoxicity of PPⅡ and PⅡwas associated with the cholesterol biosynthetic pathway disorders,which were alleviated by the cholesterol biosynthesis inhibitor lovastatin.Additionally,3-hydroxy-3-methy-lglutaryl CoA reductase(HMGCR)and squalene epoxidase(SQLE),the two rate-limiting enzymes in the choles-terol synthesis,selected as the potential targets,were confirmed by the molecular docking,the over-expression,and knockdown of HMGCR or SQLE with siRNA.Finally,the pull-down and surface plasmon resonance technology revealed that PPⅠ could directly bind with SQLE but not with HMGCR.Collectively,these data demonstrated that PPⅠ-induced hepatotoxicity resulted from the direct binding with SQLE protein and impaired the sterol-regulatory element binding protein 2/HMGCR/SQLE/lanosterol synthase pathways,thus disturbing the cholesterol biosynthesis pathway.The findings of this research can contribute to a better understanding of the key role of SQLE as a potential target in drug-induced hepatotoxicity and provide a therapeutic strategy for the prevention of drug toxic effects with similar structures in the future.
RESUMO
Objective:To investigate the effect and regulation of umbilical cord-derived mesenchymal stem cells (UC-MSCs) on islets function and NOD-like receptor family, pyrin domain containing 3 (NLRP3) and autophagy in type 2 diabetic mellitus (T2DM) mice.Methods:Experimental study. Twenty, 8-week-old, male C57BL/6J mice were selected and divided into a normal control group ( n=5) and a high-fat feeding modeling group ( n=15). The model of T2DM was established by high-fat feeding combined with intraperitoneal injection of low-dose streptozotocin. After successful modeling, those mice were divided into a diabetes group ( n=7) and a UC-MSCs treatment group ( n=7). The UC-MSCs treatment group was given UC-MSCs (1×10 6/0.2 ml phosphate buffer solution) by tail vein infusion once a week for a total of 4 weeks; the diabetes group was injected with the same amount of normal saline, and the normal control group was not treated. One week after the treatment, mice underwent intraperitoneal glucose tolerance tests and intraperitoneal insulin tolerance tests, and then the mice were sacrificed to obtain pancreatic tissue to detect the expressions of interleukin-1β (IL-1β) and pancreatic and duodenal homeobox 1 (PDX-1) by immunofluorescence. The bone marrow-derived macrophages were stimulated with lipopolysaccharide and adenosine triphosphate (experimental group) in vitro, then co-cultured with UC-MSCs for 24 h (treatment group). After the culture, enzyme-linked immunosorbent assay was used to detect the secretion level of IL-1β in the supernatant, and immunofluorescence staining was used to detect the expression of NLRP3 inflammasome, and related autophagy proteins. Statistical analysis was performed using unpaired one-way analysis of variance, repeated measure analysis of variance. Results:In vivo experiments showed that compared with the diabetes group, the UC-MSCs treatment group partially repaired islet structure, improved glucose tolerance and insulin sensitivity (all P<0.05), and the expression of PDX-1 increased and IL-1β decreased in islets under confocal microscopy. In vitro experiments showed that compared with the experimental group, the level of IL-1β secreted by macrophages in the treatment group was decreased [(85.9±74.6) pg/ml vs. (883.4±446.2) pg/ml, P=0.001], the expression of NLRP3 inflammasome and autophagy-related protein P62 was decreased, and the expressions of microtubule-associated protein 1 light chain 3β (LC3) and autophagy effector Beclin-1 were increased under confocal microscopy. Conclusions:UC-MSCs can reduce the level of pancreatic inflammation in T2DM mice, preserving pancreatic function. This might be associated with the ability of UC-MSCs to inhibit the activity of NLRP3 inflammasomes in macrophages and enhance autophagy levels.
