Rhein kills Actinobacillus pleuropneumoniae, reduces biofilm formation, and effectively treats bacterial lung infections in mice

Abstract

Abstract Actinobacillus pleuropneumoniae, a member of the Pasteurellaceae family, is known for its highly infectious nature and is the primary causative agent of infectious pleuropneumonia in pigs. This disease poses a considerable threat to the global pig industry and leads to substantial economic losses due to reduced productivity, increased mortality rates, and the need for extensive veterinary care and treatment. Rhein, as an antimicrobial compound, is one of the effective components extracted from Polygonaceae plants which has effects against kinds of bacteria. Here, in this study, we found that Rhein had a good killing effect on A. pleuropneumoniae and that the minimum inhibitory concentration (MIC) was 25 µg/mL. After 3h of action, Rhein (4×MIC) completely kills A. pleuropneumoniae and Rhein has good stability. In addition, the treatment with Rhein (1×MIC) significantly reduced the formation of bacterial biofilms. Therapeutic evaluation in a murine model showed that Rhein protects mice from A. pleuropneumoniae and relieves lung inflammation. Quantitative RT-PCR results showed that Rhein treatment significantly downregulated the expression of the IL-18ཤTNF-αཤp65ཤp38 gene. This study reports the activity of Rhein against A. pleuropneumoniae and its mechanism and reveals, the ability of Rhein to treat A. pleuropneumoniae infection in mice, laying the foundation for the development of new drugs for bacterial infections.