Bai Hu Tang, Si Ni Tang, and Xue Bi Tang amplify pro-inflammatory activities and reduce apoptosis in endothelial cells in a cell culture model of sepsis

Bai-Hu-Tang regulates endothelin-1 and its signalling pathway in vascular endothelial cells

ETHNOPHARMACOLOGICAL RELEVANCE

Bai-Hu-Tang (BHT) is traditionally used to treat human and animal fever syndrome with four symptoms: large and vigorous pulse, large thirst, high sweat, and high heat.

AIM OF THE STUDY

To investigate the mechanism of vasodilation regulation of Bai-Hu-Tang in primary vascular endothelial cells stimulated by lipopolysaccharide (LPS).

MATERIALS AND METHODS

A hydrophilic concentrate of BHT was prepared, and the main components of mangiferin and timosaponin BⅡ were determined by HLPC analysis. The rabbit fever model was constructed by intravenous injection of LPS (15 μg/kg body weight), and BHT was gavaged to treat febrile rabbits. After treatment for 6 h, animal peripheral blood was collected, and serum was isolated for endothelin-1 (ET-1) and nitric oxide (NO) assays. Rabbit vascular endothelial cells (RVECs) were isolated and stimulated with 1 μg/mL LPS, and then inflammatory cells were treated with 125 or 250 μg/mL BHT for 24 h. The supernatant cytokines TNF-ɑ, IL-1β, IL-6, and ET-1 were detected by ELISA kits. Gene expression levels of endothelin receptor type B (ET_B receptor) were analysed by real-time polymerase chain reaction (RT-PCR), and protein expression levels of PI3K and Akt were detected by Western blot. A nitrite assay was used to measure intracellular nitric oxide (NO) production, and nitric oxide synthase (NOS) was measured by the T-NOS colorimetric method.

RESULTS

Animal experiments demonstrated that BHT significantly restored ET-1 and NO in animal peripheral blood, which were disordered in LPS-induced fever rabbits. Moreover, a cytotoxicity assay demonstrated that BHT ≤700 μg/mL is innoxious to RVECs. BHT significantly repressed cellular TNF-α, IL-1β, and ET-1, which were originally elevated by LPS in RVECs. Meanwhile, BHT elevated the gene expression level of the ET_B receptor and promoted NOS and NO production in RVECs induced by LPS.

CONCLUSION

BHT can inhibit excessive ET-1 secretion induced by LPS in vascular endothelial cells and activate the classic ET-1 signalling pathway to promote NO production, which may facilitate vasodilation of smooth muscle cells.

Network Pharmacology-Based Validation of the Efficacy of Huiyangjiuji Decoction in the Treatment of Experimental Colitis

Ulcerative colitis (UC) is the major type of inflammatory bowel disease (IBD) characterized by an overactive immune responses and destruction of the colorectal epithelium with intricate pathological factors. In China, Huiyangjiuji decoction (HYJJ) has been widely administered against inflammation, but the underlying mechanical mechanisms are not known. A murine model of colitis was established by orally feeding 4% dextran sodium sulfate for 5 days. Intestinal organoids (IOs) were treated with TNFα (Tumor necrosis factor-α) as an ex-vivo UC model. A scratch assay combined with a co-culture system that incubated murine epithelial cell line (IEC-6) with macrophages (Mφs) was utilized to assess epithelial recovery under inflammatory conditions. Network pharmacology analysis was performed to elucidate the mechanism of HYJJ decoction. In the present study, we confirmed that HYJJ considerably alleviated of DSS-induced colitis, as evidenced by the improved intestinal injury and fecal albumin, as well as feces blood. Network pharmacology analysis identified the active components in HYJJ formula, and KEGG enrichment analysis indicated that HYJJ-target genes were enriched in pathogen-induced infections, cancer-related as well as inflammatory pathways. Consistently, RNA-sequencing demonstrated that HYJJ treated inhibited cytokine-cytokine interaction, IBD as well as TNF signaling pathways, confirming the anti-inflammatory and anti-neoplastic role of HYJJ decoction. In-vitro experimental evidence confirmed the suppression of pro-interleukins by HYJJ, including IL-2, IL-10 and IL-12. Moreover, the contribution of HYJJ to mucosal healing was corroborated by ex-vivo experiments, in which HYJJ rescued TNFα-compromised IOs functions, i.e., elevated mitochondrial stress (MOS) and impaired regeneration capacity. IEC-6 cells co-culture with Mφs from HYJJ-treated experimental colitis mice showed an improved migration capacity as compared to those incubated with Mφs from untreated colitis mice. We conclude that HYJJ re-establishes homeostasis of the gut epithelium during colitis by suppressing inflammation and orchestrating cytokines interaction.

Pivotal role of endothelial cell autophagy in sepsis

Sepsis is a fatal organ dysfunction resulting from a disordered host response to infection. Endothelial cells (ECs) are usually the primary targets of inflammatory mediators in sepsis; damage to ECs plays a pivotal part in vital organ failure. In recent studies, autophagy was suggested to play a critical role in the ECs injury although the mechanisms by which ECs are injured in sepsis are not well elucidated. Autophagy is a highly conserved catabolic process that includes sequestrating plasma contents and transporting cargo to lysosomes for recycling the vital substrates required for metabolism. This pathway also counteracts microbial invasion to balance and retain homeostasis, especially during sepsis. Increasing evidence indicates that autophagy is closely associated with endothelial function. The role of autophagy in sepsis may or may not be favorable depending upon conditions. In the present review, the current knowledge of autophagy in the process of sepsis and its influence on ECs was evaluated. In addition, the potential of targeting EC autophagy for clinical treatment of sepsis was discussed.

Effects of Lentinan on Endothelial Cell Activity, Inflammatory Response, Endoplasmic Reticulum Stress, and Apoptosis in Sepsis

The aim of this study is to explore the protective effects of lentinan on endoplasmic reticulum stress, inflammation, and apoptosis in sepsis endothelial cells. Firstly, lentinan was extracted, purified, and analyzed. When the concentration of lentinan was in the range of 0.04–4 μM, there was no obvious effect on the morphology of HUVECs. When the concentration reached 10 M, the cells were obviously contracted and necrotic. CCK-8 cell activity experiment showed that when the concentration of lentinan reached 4 μM, the cell activity decreased significantly (P<0.001), and it was in a dose-dependent manner. Then, the cells were divided into the control group (0 μM lentinan), sepsis group, sepsis + lentinan 1.2 μM group, and sepsis + lentinan 2 μM group. Enzyme-linked immunosorbent assay showed that lentinan could significantly reduce the expression of TNF-α, IL-1β, and IL-6 in sepsis endothelial cells (P<0.001). In addition, flow cytometry and TUNEL staining showed that compared with the control group, the apoptosis of cells in the sepsis group increased significantly (P<0.001), and lentinan could inhibit apoptosis (P<0.001). In terms of mechanism research, the mRNA and protein expression of endoplasmic reticulum stress-related protein in endothelial cells were detected by real-time fluorescent quantitative PCR (qPCR) and Western blotting, respectively. It was found that the expression of SIRT1, the upstream factors of endoplasmic reticulum stress in sepsis cells, was obviously inhibited (P<0.001), and the expression of CHOP, GRP78, IRE1α, and ATF6 was significantly increased (P<0.001), However, the pretreatment of lentinan could significantly reverse the above changes (P<0.001). Besides, lentinan could also reduce the expression of phosphorylated p65 protein (the activation marker of NF-κb) and iNOS. Conclusion. When sepsis occurs, lentinan can protect endothelial cells from ERS inflammation and apoptosis induced by sepsis. Thus, lentinan is expected to be a new target for the treatment of sepsis-induced endothelial damage.