Jiangqi Pingxiao formula regulates dendritic cell apoptosis in an autophagy-dependent manner through the AMPK/mTOR pathway in a murine model of OVA-induced asthma.

ETHNOPHARMACOLOGICAL RELEVANCE: Allergic asthma is a recurring respiratory condition that typically manifests during childhood or adolescence. It is characterized by a dominant type II immune response triggered by the identification and capturing of inhaled allergens by dendritic cells (DCs). Jiangqi Pingxiao Formula (JQPXF), a prescription medicine used for the treatment of pediatric asthma, has been clinically proven to be both safe and effective. However, its mechanism of action in the treatment of asthma has not been fully been fully elucidated. Recent research suggests that several natural compounds have the potential to target dendritic cells (DCs) and alleviate ovalbumin (OVA)-induced asthma, which may also be found within JQPXF. AIM OF THE STUDY: This study aimed to elucidate the effect of JQPXF on OVA-induced asthma model and its molecular mechanism targeting DCs. MATERIALS AND METHODS: The main constituents of JQPXF were analyzed by ultra performance liquid chromatography (UPLC). An asthma model was established by OVA. Hematoxylin-eosin staining and measurement of respiratory function was used to evaluate the treatment effect of JQPXF on asthmatic mice. Cytokine (IL-5, IL-13 and IgE) concentrations were determined by enzyme-linked immunosorbent assay (ELISA). Flow cytometry was employed to evaluate inflammatory cell infiltration (T helper 2 cells and DCs) in vivo and DC survival in vivo and vitro. Western blot and immunofluorescence were used to verify the molecular mechanisms. RESULTS: The results suggest that JQPXF can ameliorate pathological conditions and improve lung function in asthmatic mice, as well as the Th2 cells. Treatment with JQPXF significantly reduced the number of DCs and increased the number of Propidium iodide+ (PI) DCs. Furthermore, JQPXF upregulated protein levels of the pro-apoptotic factors Cleaved-caspase-3 and Bax, while downregulating the anti-apoptotic factor Bcl-2. Simultaneously, JQPXF increased autophagy levels by facilitating p62 degradation and promoting translation from LC3B I to LC3B II of DCs in vitro, as well as reducing the integrated optical density (IOD) of p62 within the CD11c-positive area in the lung. 3-Methyladenine (3-MA) was used to block autophagic flux and the apoptotic effect of JQPXF on DCs was abolished in vitro, with the number of DCs decreased by JQPXF being reversed in vivo. We further investigated the upstream key regulator of autophagy, the AMPK/mTOR pathway, and found that JQPXF increased AMPK phosphorylation while decreasing mTOR phosphorylation levels. Additionally, we employed Compound C (CC) as an AMPK inhibitor to inhibit this signaling pathway, and our findings revealed that both autophagic flux and apoptotic levels in DCs were abolished in vitro. CONCLUSIONS: In summary, we have demonstrated that JQPXF could alleviate type II inflammation in an asthmatic model by promoting the apoptosis of DCs through an autophagy-dependent mechanism, achieved by regulating the AMPK/mTOR signaling pathway.

Inhibition of α-toxin production by subinhibitory concentrations of naringenin controls Staphylococcus aureus pneumonia.

Staphylococcal pneumonia provoked by methicillin-resistant Staphylococcus aureus (MRSA) is a life-threatening infection in which α-toxin is an essential virulence factor. In this study, we investigate the influence of naringenin on α-toxin production and further assess its therapeutic performance in the treatment of staphylococcal pneumonia. Remarkably, the expression of α-toxin was significantly inhibited when the organism was treated with 16 µg/ml of naringenin. When studied in a mouse model of S. aureus pneumonia, naringenin could attenuate the symptoms of lung injury and inflammation in infected mice. These results suggest that naringenin is a promising agent for treatment of S. aureus infection.

Silibinin in vitro protects A549 cells from Staphylococcus aureus-mediated injury and in vivo alleviates the lung injury of staphylococcal pneumonia.

In this study, hemolysis, Western blot, and real-time RT-PCR assays were performed to evaluate silibinin's activity against S. aureus α-toxin secretion. In addition, live/dead cell staining and lactate dehydrogenase activity assays were introduced to examine the influence of silibinin on α-toxin-induced cell injury in human alveolar epithelial cells. Furthermore, we tested the influence of silibinin on S. aureus pneumonia in a mouse model. We show that silibinin inhibits the expression of α-toxin in a dose-dependent manner and alleviates α-toxin-induced lung cell injury. The IC50 of silibinin that inhibits the hemolytic activity of S. aureus was 14.33 µg/mL for strain 8325-4. Moreover, this compound provides effective protection on the lung injury of staphylococcal pneumonia.

Glycyrrhetinic acid protects mice from Staphylococcus aureus pneumonia.

In the present study, the antimicrobial activity of glycyrrhetinic acid (GA) against Staphylococcus aureus, and its influence on the production of S. aureus alpha-haemolysin (Hla) were investigated, along with the in vivo activity of GA against S. aureus-induced pneumonia. GA could not inhibit the growth of S. aureus, but the secretion of Hla by S. aureus was significantly inhibited by low concentrations of GA in a dose-dependent manner. Furthermore, in vivo data show that GA provides protection against staphylococcal pneumonia in a murine model system.

Isoalantolactone protects against Staphylococcus aureus pneumonia.

Staphylococcus aureus is a versatile pathogen that can cause life-threatening infections. The growing emergence of methicillin-resistant S. aureus strains and a decrease in the discovery of new antibiotics warrant the search for new therapeutic targets to combat infections. Staphylococcus aureus produces many extracellular virulence factors that contribute to its pathogenicity. Therefore, targeting bacterial virulence as an alternative strategy to the development of new antimicrobials has gained great interest. α-Toxin is a 33.2-kDa, water-soluble, pore-forming toxin that is secreted by most S. aureus strains. α-Toxin is essential for the pathogenesis of pneumonia, as strains lacking α-toxin display a profound defect in virulence. In this report, we demonstrate that isoalantolactone (IAL), a naturally occurring compound found in Inula helenium (Compositae), has no anti-S. aureus activity as per MIC evaluation in vitro. However, IAL can markedly inhibit the expression of α-toxin in S. aureus at very low concentrations. Furthermore, the in vivo data indicate that treatment with IAL protects mice from S. aureus pneumonia.