Protective effects of the RAGE inhibitor azeliragon as a potential anti-Streptococcus pneumoniae therapeutic in sepsis models.

The increasing antimicrobial resistance of Streptococcus pneumoniae (S. pneumoniae) presents a major therapeutic challenge and underscores the need for agents with novel mechanisms of action. Azeliragon is a small-molecule inhibitor of the receptor for advanced glycation end products (RAGE), but its antibacterial activity has not been well defined. In this study, we systematically evaluated the in vitro and in vivo anti-infective effects of azeliragon against S. pneumoniae. Azeliragon exhibited minimum inhibitory concentration (MIC) values predominantly ranging from 4 to 8 μg/mL, with MIC₅₀ and MIC₉₀ values of 4 μg/mL and 8 μg/mL against clinical isolates, respectively. Growth-curve and time-kill assays demonstrated concentration- and time-dependent antibacterial activity, resulting in a marked reduction in viable bacteria within 6-8 h at 4× MIC. Azeliragon also significantly reduced the biomass of mature S. pneumoniae biofilms. Mechanistic analyses showed that azeliragon disrupted bacterial membrane integrity and increased intracellular reactive oxygen species levels, indicating that membrane damage and enhanced oxidative stress contribute to its bactericidal effect. in vivo, azeliragon conferred significant protection in a mouse infection model of S. pneumoniae, improving survival to approximately 60-70%. In a non-lethal infection model, azeliragon markedly reduced bacterial loads in blood and lung tissues and significantly decreased serum levels of pro-inflammatory cytokines, including TNF-α and IL-6. Collectively, these findings provide the first systematic evidence that the RAGE inhibitor azeliragon exerts direct anti-S. pneumoniae activity and affords in vivo protection, supporting its potential as a novel antibacterial candidate for pneumococcal infections.