Rhein Confers Protection Against Pneumococcal Pneumonia via Immunomodulation of the MAPK/NF-κB Axis

Area of Science:

• Immunology
• Pharmacology
• Microbiology

Background:

• Streptococcus pneumoniae is a primary cause of community-acquired pneumonia.
• Severe pneumonia involves inflammation driven by Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-κB) and Mitogen-Activated Protein Kinase (MAPK) pathways.

Purpose of the Study:

• To evaluate the immunomodulatory effects of rhein in a mouse model of Streptococcus pneumoniae-induced pneumonia.
• To investigate rhein's impact on inflammatory mediators and signaling pathways.

Main Methods:

• Mice were infected with S. pneumoniae and treated with rhein (10 mg/kg or 30 mg/kg).
• Lung tissue and bronchoalveolar lavage fluid (BALF) were analyzed for inflammatory markers (cytokines, COX-2, iNOS) using RT-PCR and ELISA.
• MAPK and NF-κB phosphorylation levels were assessed via ELISA and Western blotting.

Main Results:

• Rhein treatment reduced lung injury markers, bacterial load, and expression of COX-2 and iNOS.
• Pro-inflammatory cytokines (IL-6, IL-1β, TNF-α, MCP-1) decreased, while anti-inflammatory IL-10 increased.
• Rhein significantly inhibited the phosphorylation of MAPK and NF-κB signaling pathways.

Conclusions:

• Rhein attenuates S. pneumoniae-induced pulmonary inflammation and injury.
• Modulation of MAPK/NF-κB pathways by rhein is key to its therapeutic effect.
• Rhein shows promise as a potential treatment for pneumococcal pneumonia and related lung inflammation.