Protective Effect of Silibinin on Lipopolysaccharide-Induced Endotoxemia by Inhibiting Caspase-11-Dependent Cell Pyroptosis

OBJECTIVE

To explore the protective effect and the underlying mechanism of silibinin (SIB), one of the active compounds from Silybum marianum (L.) Gaertn in endotoxemia.

METHODS

Mouse peritoneal macrophage were isolated via intraperitoneally injection of BALB/c mice with thioglycolate medium. Cell viability was assessed using the cell counting kit-8, while cytotoxicity was determined through lactate dehydrogenase cytotoxicity assay. The protein expressions of interleukin (IL)-1 α, IL-1 β, and IL-18 were determined by enzyme-linked immunosorbent assay. Intracellular lipopolysaccharide (LPS) levels were measured by employing both the limulus amoebocyte lysate assay and flow cytometry. Additionally, proximity ligation assay was employed for the LPS and caspase-11 interaction. Mice were divided into 4 groups: the control, LPS, high-dose-SIB (100 mg/kg), and low-dose-SIB (100 mg/kg) groups (n=8). Zebrafish were divided into 4 groups: the control, LPS, high-dose-SIB (200 εmol/L), and low-dose-SIB (100 εmol/L) groups (n=30 for survival experiment and n=10 for gene expression analysis). The expression of caspase-11, gasdermin D (GSDMD), and N-GSDMD was determined by Western blot and the expressions of caspy2, gsdmeb, and IL-1 β were detected using quantitative real-time PCR. Histopathological observation was performed through hematoxylineosin staining, and protein levels in bronchoalveolar lavage fluid were quantified using the bicinchoninicacid protein assay.

RESULTS

SIB noticeably decreased caspase-11 and GSDMD-mediated pyroptosis and suppressed the secretion of IL-1 α, IL-1 β, and IL-18 induced by LPS (P<0.05). Moreover, SIB inhibited the translocation of LPS into the cytoplasm and the binding of caspase-11 and intracellular LPS (P<0.05). SIB also attenuated the expression of caspase-11 and N-terminal fragments of GSDMD, inhibited the relative cytokines, prolonged the survival time, and up-regulated the survival rate in the endotoxemia models (P<0.05).

CONCLUSIONS

SIB can inhibit pyroptosis in the LPS-mediated endotoxemia model, at least in part, by inhibiting the caspase-11-mediated cleavage of GSDMD. Additionally, SIB inhibits the interaction of LPS and caspase-11 and inhibits the LPS-mediated up-regulation of caspase-11 expression, which relieves caspase-11-dependent cell pyroptosis and consequently attenuates LPS-mediated lethality.

N-Butanol Extract of Glycyrrhizae Radix et Rhizoma Inhibits Dengue Virus through Targeting Envelope Protein

BACKGROUND

At present, about half of the world's population is at risk of being infected with dengue virus (DENV). However, there are no specific drugs to prevent or treat DENV infection. Glycyrrhizae Radix et Rhizome, a well-known traditional Chinese medicine, performs multiple pharmacological activities, including exerting antiviral effects. The aim of this study was to investigate the anti-DENV effects of n-butanol extract from Glycyrrhizae Radix et Rhizome (GRE).

METHODS

Compounds analysis of GRE was conducted via ultra-performance liquid chromatography/tandem mass spectrometry (UHPLC-MS/MS). The antiviral activities of GRE were determined by the CCK-8 assay, plaque assay, qRT-PCR, Western blotting, and the immunofluorescence assay. The DENV-infected suckling mice model was constructed to explore the antiviral effects of GRE in vivo.

RESULTS

Four components in GRE were analyzed by UHPLC-MS/MS, including glycyrrhizic acid, glycyrrhetnic acid, liquiritigenin, and isoliquiritigenin. GRE inhibited the attachment process of the virus replication cycle and reduced the expression of the E protein in cell models. In the in vivo study, GRE significantly relieved clinical symptoms and prolong survival duration. GRE also significantly decreased viremia, reduced the viral load in multiple organs, and inhibited the release of pro-inflammatory cytokines in DENV-infected suckling mice.

CONCLUSIONS

GRE exhibited significant inhibitory activities in the adsorption stage of the DENV-2 replication cycle by targeting the envelope protein. Thus, GRE might be a promising candidate for the treatment of DENV infection.

Anti-inflammatory, anti-angiogenetic and antiviral activities of dammarane-type triterpenoid saponins from the roots of Panax notoginseng

Panax notoginseng has been used both as a traditional medicine and as a functional food for hundreds of years in Asia. However, the active constituents from P. notoginseng and their pharmacologic properties still need to be further explored. In this study, one new dammarane-type triterpenoid saponin (1), along with fourteen known analogs (2-15) were isolated and identified from the roots of P. notoginseng. The anti-inflammatory, anti-angiogenetic and anti-dengue virus effects of these isolated compounds were further evaluated. Compounds 1, 3, 5-7 and 10-12 exerted anti-inflammatory effects in two different zebrafish inflammatory models. Among them, 11, with the most significant activities, alleviated the inflammatory response by blocking the MyD88/NF-κB and STAT3 pathways. Moreover, compound 15 showed anti-angiogenetic activities in Tg(fli1:EGFP) and Tg(flk1:GFP) zebrafish, while 3 and 5 only inhibited angiogenesis in Tg(fli1:EGFP) zebrafish. Additionally, compounds 1, 3, 6, 8, 9 and 12 suppressed the replication of dengue virus either at the viral adsorption and entry stages or at the intracellular replication step. In conclusion, these findings enrich knowledge of the diversity of saponins in P. notoginseng and suggest that the dammarane-type triterpenoid saponins from P. notoginseng may be developed as potential functional foods to treat inflammation, angiogenesis or dengue-related diseases.

[Epstein-Barr virus infection-related post-transplant lymphoproliferative disorders in transplanted lung: a clinicopathological analysis]

Objective: To investigate the clinicpathological characteristics of post-transplant lymphoproliferative disorders (PTLD) in transplanted lung, and to improve its diagnosis and treatment. Methods: The clinicopathological characteristics of PTLD in three transplanted lungs were evaluated at Wuxi People's Hospital Affiliated to Nanjing Medical University from 2014 to 2019. HE, immunohistochemical staining and in situ hybridization were performed. The relevant literature of PTLD was reviewed. Results: All three patients had chronic obstructive pulmonary disease (COPD) before lung transplantation. After receiving both lung transplants, they were all treated with anti-rejection drugs tacrolimus or mycophenolate mofetil, and combined with antiviral and/or rituximab. The time from transplantation to diagnosis of PTLD was four years, seven months, and five months, respectively. Two patients died one month and five months after initial diagnosis, and one patient was alive with no disease after one year. Histologically, all cases were monomorphic B-cell PTLD (diffuse large B-cell lymphoma, unspecified), and the tumor cells were positive for Epstein-Barr virus by in situ hybridization; one of the late-onset patients had herpes simplex virus infection. Conclusions: PTLD in the post-transplant lung tissue shows unique morphology and clinical characteristics, and is closely related to Epstein-Barr virus infection. Patients who receive lung transplantation due to COPD are more susceptible to develop PTLD, while late-onset ones occur more commonly in the hilum of lungs, and the prognosis is relatively poor.

Evaluation of an enzyme immunoassay for the detection of antibodies against Sarcocystis spp. in naturally infected cattle in China

An enzyme immunoassay was used to detect anti-Sarcocystis antibodies in the sera of 159 cattle sent to slaughter in Jilin Province, north China. The musculature of each carcase was closely examined for the presence of parasitic cysts and aliquots of muscle were digested with pepsin and examined microscopically for cystozoites. Specific antibodies were detected in 126 (79.25%) cattle whereas cystozoites were detected in 123 (77.36%) and cysts in 103 (64.78%). The accuracy, sensitivity and specificity of the enzyme immunoassay were high (0.97, 0.99 and 0.91, respectively) and false reactions were only detected in four cases. The assay exhibited a high level of reproducibility when samples were re-tested and the soluble Sarcocystis spp. antigens did not cross-react with anti-Toxoplasma antibodies raised in rabbits. This report presents the first successful application of an enzyme immunoassay in the diagnosis of Sarcocystis spp. infections in naturally infected cattle in China. The assay, however, failed to detect specific antibodies in four dogs experimentally infected with S. cruzi from cattle.