Isorhamnetin as a novel inhibitor of pneumolysin against Streptococcus pneumoniae infection in vivo/in vitro

The increasing incidence of Streptococcus pneumoniae (S. pneumoniae) infection severely threatened the global public heath, causing a significant fatality in immunocompromised hosts. Notably, pneumolysin (PLY) as a pore-forming cytolysin plays a crucial role in the pathogenesis of pneumococcal pneumonia and lung injury. In this study, a natural flavonoid isorhamnetin was identified as a PLY inhibition to suppress PLY-induced hemolysis by engaging the predicted residues and attenuate cytolysin PLY-mediated A549 cells injury. Underlying mechanisms revealed that PLY inhibitor isorhamnetin further contributed to decrease the formation of bacterial biofilms without affecting the expression of PLY. In vivo S. pneumoniae infection confirmed that the pathological injury of lung tissue evoked by S. pneumoniae was ameliorated by isorhamnetin treatment. Collectively, these results presented that isorhamnetin could inhibit the biological activity of PLY, thus reducing the pathogenicity of S. pneumoniae. In summary, our study laid a foundation for the feasible anti-virulence strategy targeting PLY, and provided a promising PLY inhibitor for the treatment of S. pneumoniae infection.

Shionone-Targeted Pneumolysin to Ameliorate Acute Lung Injury Induced by Streptococcus pneumoniae In Vivo and In Vitro

Streptococcus pneumoniae (S. pneumoniae), as a Gram-positive bacterium, can cause severe bacterial pneumonia, and result in high morbidity and mortality in infected people. Meanwhile, isolated drug-resistant S. pneumoniae is growing, which raises concerns about strategies for combatting S. pneumoniae infection. To disturb S. pneumoniae pathogenicity and its drug-resistance, developing novel anti-infective strategies or compounds is urgent. In this study, the anti-infective effect of shionone was explored. A minimum inhibitory concentration (MIC) assay and growth curve determination were performed to evaluate the effect of the tetracyclic triterpenoid compound shionone against S. pneumoniae. Hemolysis tests, western blotting, oligomerization inhibition assays, and molecular docking were carried out to explore the anti-infective mechanism of shionone. Moreover, the protective effect of shionone was also confirmed in a mousepneumonia model. The results showed that the excellent hemolytic inhibitory activity of shionone was observed at less than 8 μg/mL. Meanwhile, shionone could disturb the oligomerization of pneumolysin (PLY) but did not interfere with PLY expression at less than 4 μg/mL. Molecular docking suggested that shionone targeted the ASP-59, ILE-60, THR-57, PHE-344, and ASN-346 amino acid sites to reduce S. pneumoniae pathogenicity. Furthermore, shionone alleviated lung histopathologic injury and decreased lung bacterial colonization in vivo. The above results showed that shionone could bind to the PLY active pocket under the concentrations of 8 μg/mL and neutralize PLY hemolysis activity to reduce S. pneumoniae pathogenicity in vitro and in vivo.

Quercetin, a pneumolysin inhibitor, protects mice against Streptococcus pneumoniae infection

Pneumolysin (PLY), a pore-forming cytotoxin and a major virulence determinant, is a member of the cholesterol-dependent cytolysin (CDC) family and essential for promoting Streptococcus pneumoniae (S.pneumoniae) infection. Due to the action characteristics of hemolysin itself, the pneumolysin released after killing bacteria with conventional antibiotics still has the ability to damage host cells; therefore, drug treatments directly inhibiting hemolysin activity are the most effective. Hemolysis assays were used to confirm that quercetin can inhibit the activity of PLY, protecting cells in vitro, and an oligomerization assay was used to determine the mechanism of quercetin to suppress PLY activity. Live/Dead testing, lactate dehydrogenase (LDH) release analysis and a murine model of endonasal pulmonary infection were used to explore the capability of quercetin to protect cells and mice from S. pneumoniae-mediated damage in vivo and in vitro. The results indicated that quercetin significantly reduced PLY-induced hemolytic activity and cytotoxicity via repressing the formation of oligomers. In addition, treatment with quercetin can reduce PLY-mediated cell injury, improve the survival rate of mice infected with a lethal dose of S. pneumoniae, alleviate the pathological damage of lung tissue and inhibit the release of cytokines (IL-1β and TNF-α) in bronchoalveolar lavage fluid. Considering the importance of these events in antimicrobial resistant S. pneumoniae pathogenesis, our results indicated that quercetin may be a novel potential drug candidate for the treatment of clinical pneumococcal infections.

Morin reduces inflammatory responses and alleviates lipid accumulation in hepatocytes

Morin (MO), a natural bioflavinoid, exists in many herbs. Previous studies have acclaimed MO's anti-inflammatory, antidiabetic, antioxidant, antifibrotic, anticancer, and antihyperglycemic biological effects. This study aimed to assess the molecular mechanism of MO involved in the oleic acid (OA)-induced inflammatory damage and lipid accumulation in HepG2 cell and tyloxapol (Ty)-induced hyperlipidemia in mice. We found that MO can efficaciously mitigate reactive tumor necrosis factor-α (TNF-α) level and triglyceride (TG) accumulation in OA-induced HepG2 cell and in tyloxapol-induced mice. Next, the study testified that MO apparently suppressed OA-excited nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) signaling pathways in HepG2 cell. In addition, MO distinctly upregulated the expression of peroxisome proliferator-activated receptor α (PPARα) and decreased the expression of sterol regulatory element-binding protein 1c (SREBP-1c) in OA-induced HepG2 cell and in tyloxapol-induced mice, both of which are dependent upon the phosphorylation of acetyl-CoA carboxylase (ACC), adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK), and protein kinase B (AKT). In conclusion, these results suggest that MO has protective potential against hyperlipidemia and steatosis, and the potential mechanism may have a close relation with activation of PPARα and inhibition of SREBP-1c.

Effect of extended-duration thromboprophylaxis on venous thromboembolism and major bleeding among acutely ill hospitalized medical patients: a bivariate analysis

Essentials Anticoagulants prevent venous thromboembolism but may be associated with greater bleeding risks. Bivariate analysis assumes a non-linear relationship between efficacy and safety outcomes. Extended full-dose betrixaban is favorable over standard enoxaparin in bivariate endpoint. Clinicians must weigh efficacy and safety outcomes in decision-making on thromboprophylaxis.

SUMMARY

Background Among acutely ill hospitalized medical patients, extended-duration thromboprophylaxis reduces the risk of venous thromboembolism (VTE), but some pharmacologic strategies have been associated with greater risks of major bleeding, thereby offsetting the net clinical benefit (NCB). Methods To assess the risk-benefit profile of anticoagulation regimens, a previously described bivariate method that does not assume a linear risk-benefit tradeoff and can accommodate different margins for efficacy and safety was performed to simultaneously assess efficacy (symptomatic VTE) and safety (major bleeding) on the basis of data from four randomized controlled trials of extended-duration (30-46 days) versus standard-duration (6-14 days) thromboprophylaxis among 28 227 patients (EXCLAIM, ADOPT, MAGELLAN and APEX trials). Results Extended thromboprophylaxis with full-dose betrixaban (80 mg once daily) was superior in efficacy and non-inferior in safety to standard-duration enoxaparin, and showed a significantly favorable NCB, with a risk difference of - 0.51% (- 0.89% to - 0.10%) in the bivariate outcome. Extended enoxaparin was superior in efficacy and inferior in safety (bivariate outcome: 0.03% [- 0.37% to 0.43%]), whereas apixaban and rivaroxaban were non-inferior in efficacy and inferior in safety (- 0.20% [- 0.49% to 0.17%] and 0.23% [- 0.16% to 0.69%], respectively). Reduced-dose betrixaban did not show a significant difference in either efficacy or safety (0.41% [- 0.85% to 1.94%]). Conclusions In a bivariate analysis that assumes non-linear risk-benefit tradeoffs, extended prophylaxis with full-dose betrixaban was superior to standard-duration enoxaparin, whereas other regimens failed to simultaneously achieve both superiority and non-inferiority with respect to symptomatic VTE and major bleeding in the management of acutely ill hospitalized medical patients.

D(-)-Salicin inhibits the LPS-induced inflammation in RAW264.7 cells and mouse models

D(-)-Salicin is a traditional medicine which has been known to exhibit anti-inflammation and other therapeutic activities. The present study aimed to investigate whether D(-)-Salicin inhibited the LPS-induced inflammation in vivo and in vitro. We evaluated the effect of D(-)-Salicin on cytokines (TNF-α, IL-1β, IL-6 and IL-10) in vivo and in vitro by enzyme-linked immunosorbent assay and signaling pathways (MAPKs and NF-κB) in vivo by Western blot. The results showed that D(-)-Salicin markedly decreased TNF-α, IL-1β and IL-6 concentrations and increased IL-10 concentration. In addition, western blot analysis indicated that D(-)-Salicin suppressed the activation of MAPKs and NF-κB signaling pathways stimulated by LPS. To examine whether D(-)-Salicin ameliorated LPS-induced lung inflammation, inhibitors of MAPKs and NF-κB signaling pathways were administrated intraperitoneally to mice. Interference with specific inhibitors revealed that D(-)-Salicin-mediated cytokine suppression was through MAPKs and NF-κB pathways. In the mouse model of acute lung injury, histopathologic examination indicted that D(-)-Salicin suppressed edema induced by LPS. So it is suggest that D(-)-Salicin might be a potential therapeutic agent against inflammatory diseases.

[An epidemiological analysis on the relationship between road injury and traffic environment in China]

OBJECTIVE

To explore the influence of traffic environment on road injury so as to provide basis for prevention and control.

METHODS

Principal component regression analysis was used to explain the relationship between road injury and the numbers of vehicle, capacity of road transport and mileage of rigid highway.

RESULTS

Results showed a positive correlation between level of personal safety (LPS) and the numbers of vehicle, volume of road haulage, volume of passenger transport, mileage of rigid highway (correlation coefficients were 0.8714, 0.9691, 0.9611, 0.9510, P = 0.0005). The numbers of vehicle, volume of road haulage, volume of passenger transport and mileage of rigid highway were increasing when LPS decreased. Principal component regression analysis overcame multi collinearty of independent variables and obtained a regression equation y =-3.7197 + 1.49E-03X(1) + 5.2E-06X(3) + 6.19E-02X(4).

CONCLUSION

The primary determinants of LPS were numbers of vehicle, volume of road haulage, volume of passenger and mileage of rigid highway. Road injury thus could be reduced through improving the traffic environment, strengthening the traffic administration as well as promoting traffic safety.

[Epidemiologic features and the stepwise regression analysis of fatal motor vehicle accidents in Guangzhou]

This paper describes the epidemiologic features of 1,532 fatal motor vehicle crashes, and analyses of some crash-related factors by means of stepwise regression analysis as well. The crashes between motor vehicle and bicycle accounted for 39.49 percent. The 36.84 percent of drivers responsible for accidents were at the age of 20-24. The analysis of accident victim characteristics indicated that all age groups were at risk. Most victims were the people younger than 25 years old as well as aged 50 and over. About one-third of the victims were peasants. The analysis of stepwise regression suggested that the crashes were positively related to the quantity of automobile and the ratio between male and female.