Umbilical cord stem cells therapy against bacterial pneumonia based on zebrafish pneumonia model.

BACKGROUND: The increasing incidence and mortality rates of respiratory system diseases globally pose a significant public health challenge. Bacterial pneumonia is one of the leading risk factors for acute lung injury. Conventional antibiotics face inherent limitations, particularly the increase in bacterial resistance and inability to suppress inflammatory states, underscoring the urgent need for novel approaches to combat bacterial pneumonia. METHODS: This study evaluated the therapeutic effects of umbilical cord mesenchymal stem cells (UC-MSCs) on bacterial pneumonia in a zebrafish model, focusing on their impact on macrophage and neutrophil counts and their inhibitory effects on in vivo inflammatory responses. The anti-inflammatory mechanisms of UC-MSCs, including their effects on the secretion of inflammatory factors IL-1β, IL-6, and TNF-α, as well as their regulation of NLRP3, TLR4, and NF-kB mRNA expression and NLRP3, p65, and TLR4 protein levels, were further investigated. RESULTS: Our study found that UC-MSCs can effectively inhibit the development of bacterial pneumonia, primarily by reducing the number of macrophages and neutrophils and inhibiting the secretion of inflammatory factors IL-1β, IL-6, and TNF-α, thereby suppressing in vivo inflammatory reactions. Additionally, UC-MSCs significantly downregulated the expression of NLRP3, TLR4, and NF-kB mRNA, as well as the levels of NLRP3,TLR4, and p65 proteins. CONCLUSION: UC-MSCs demonstrate promising potential in the treatment of bacterial pneumonia. This study provides important reference for the therapeutic effects and mechanisms of stem cell treatment of bacterial pneumonia, offering new avenues for clinical applications.