Sodium houttuyfonate effectively treats acute pulmonary infection of Pseudomonas aeruginosa by affecting immunity and intestinal flora in mice

Sodium houttuyfonate induces bacterial lipopolysaccharide shedding to promote macrophage M1 polarization against acute bacterial lung infection

Sodium houttuyfonate (SH), derived from the widely utilized natural herb Houttuynia cordata, exhibits an effective therapeutic effect on various diseases, including bacterial and fungal infections, especially the respiratory tract infection. Therefore, the anti-microbial mechanisms of SH may be different from the single-target action mechanism of conventional antibiotics, and further research is needed to clarify this. Firstly, we discovered that SH can effectively intervene in mouse lung infections by reducing bacterial load and acute inflammation response related to pneumonia caused by Pseudomonas aeruginosa. Interestingly, our results confirmed that SH has surface activity and can directly induce changes in the cell wall the shedding of surface lipopolysaccharide (LPS). Additionally, we found that SH-induced shedding of LPS can induce M1 polarization of macrophages in the early stage, leading to the production of corresponding polarization effector molecules. Subsequently, we discovered that SH-induced M1 polarization cells can effectively phagocytose and kill bacterial cells. The protein expression results indicated that SH can enhance the expression of M1 polarization pathway of TLR4/MyD88/NF-κB during the initial phase of macrophage and pathogen interaction. In summary, our results imply that SH could directly induce the shedding of P. aeruginosa LPS in a surfactant-like manner. Afterwards, the SH induced abscisic LPS can initiate the TLR4/MyD88/NF-κB immune pathway to trigger the M1 polarization of macrophages, which might intervene the P. aeruginosa-caused acute lung infection at early stage. Based on these findings, we attempted to coin the term "immune feedback eradication mechanism against pathogen of natural product" to describe this potent antimicrobial mechanism of SH.

Sodium houttuyfonate modulates the lung Th1/Th2 balance and gut microbiota to protect against pathological changes in lung of ovalbumin-induced asthmatic mice

OBJECTIVE

The gut-lung axis involves microbial and product interactions between the lung and intestine. Antibiotics for chronic asthma can cause intestinal dysbiosis, disrupting this axis. Sodium houttuyfonate (SH) has diverse biological activities, including modifying gut microbiota, antibacterial, and anti-inflammatory. This study aims to explore the relationship between SH, CD4+ T cells, and gut microbiota.

METHODS

Allergic asthma was experimentally induced in mice through injection and inhalation of ovalbumin. After the administration of different amounts of SH, ELISA was utilized to ascertain the levels of inflammatory cytokines in the serum, flow cytometry was used to examine the levels of Th1/Th2 cytokines in CD4+ cells from lung tissues. The expression of T-bet and GATA3 in lung tissue was determined by Western blotting and quantitative real-time PCR assay. Gut microbiota was determined by 16S rRNA gene sequencing.

RESULTS

The results showed that SH can alleviate pulmonary injury in asthmatic mice, reducing serum levels of IL-4, IL-5, and IL-13 while simultaneously increasing IFN-γ. Furthermore, SH has been observed to modulate the balance of Th1/Th2 cells by up-regulating the mRNA and protein expression of T-bet but down-regulating GATA3 in the lung tissues of asthmatic mice, thereby promoting the differentiation of Th1 cells. Additionally, SH can regulate the variety and composition of gut microbiota especially genus Akkermansia in asthmatic mice.

CONCLUSION

SH can alleviate asthma through the regulation of Th1/Th2 cells and gut microbiota.

Quercetin attenuates Pseudomonas aeruginosa-induced acute lung inflammation by inhibiting PI3K/AKT/NF-κB signaling pathway

Pseudomonas aeruginosa is an opportunistic pathogen that commonly causes infections in immunocompromised individuals with significant morbidity and mortality. Quercetin is a natural flavonoid abundantly present in fruits and vegetables, exerting potent anti-inflammatory effects in treatment of various diseases. However, the molecular mechanisms of quercetin in treatment of P. aeruginosa-induced acute lung inflammation are unclear. In this study, we exploited network pharmacology- and molecular docking-based approach to explore the potential mechanisms of quercetin against P. aeruginosa pneumonia, which was further validated via in vivo and in vitro experiments. The in vivo experiments demonstrated that quercetin alleviated the P. aeruginosa-induced lung injury by diminishing neutrophil infiltration and production of proinflammatory cytokines (IL-1β, IL-6, and TNF), which was associated with decreased mortality. Moreover, the quercetin-treated mice displayed decreased phosphorylation levels of PI3K, AKT, IκBα, and NF-κB p65 in lung tissues compared to non-drug-treated mice. Similarly, the in vitro study showed that the phosphorylation of these regulatory proteins and production of the proinflammatory cytokines were impaired in the quercetin-pretreated macrophages upon P. aeruginosa infection. Altogether, this study suggested that quercetin reduced the P. aeruginosa-induced acute lung inflammation by suppressing PI3K/AKT/NF-κB signaling pathway.

A new perspective on gut-lung axis affected through resident microbiome and their implications on immune response in respiratory diseases

The highly diverse microbial ecosystem of the human body colonizes the gastrointestinal tract has a profound impact on the host's immune, metabolic, endocrine, and other physiological processes, which are all interconnected. Specifically, gut microbiota has been found to play a crucial role in facilitating the adaptation and initiation of immune regulatory response through the gastrointestinal tract affecting the other distal mucosal sites such as lungs. A tightly regulated lung-gut axis during respiratory ailments may influence the various molecular patterns that instructs priming the disease severity to dysregulate the normal function. This review provides a comprehensive summary of current research on gut microbiota dysbiosis in respiratory diseases including asthma, pneumonia, bronchopneumonia, COPD during infections and cancer. A complex-interaction among gut microbiome, associated metabolites, cytokines, and chemokines regulates the protective immune response activating the mucosal humoral and cellular response. This potential mechanism bridges the regulation patterns through the gut-lung axis. This paper aims to advance the understanding of the crosstalk of gut-lung microbiome during infection, could lead to strategize to modulate the gut microbiome as a treatment plan to improve bad prognosis in various respiratory diseases.