Inflammatory Phenotypes In Severe Pneumonia: Clinical Evidence To Mouse Models For Precision Therapeutics.

Summary

In 548 ICU patients with pulmonary sepsis, latent class analysis identified hyperinflammatory and hypoinflammatory phenotypes with divergent lung injury and mortality. A pneumococcal pneumonia mouse model reproduced these phenotypes, and dexamethasone or IL-6 receptor blockade was beneficial exclusively in the more inflamed phenotype, providing a translational framework for phenotype-targeted therapy.

Key Findings

• Latent class analysis of 548 patients with pulmonary sepsis identified hyperinflammatory and hypoinflammatory phenotypes.
• The hyperinflammatory phenotype was associated with greater lung injury and higher mortality.
• Anti-inflammatory treatment benefited only the more inflamed phenotype in the mouse model.

Clinical Implications

Inflammatory biomarker phenotyping could eventually identify patients most likely to benefit from corticosteroids or IL-6 pathway blockade while avoiding ineffective or harmful treatment in hypoinflammatory patients. Prospective clinical trials using phenotype-based enrollment are needed before routine implementation.

Limitations

• The clinical phenotype analysis was observational and cannot establish that the phenotypes cause treatment response.
• The mouse model may not capture the full heterogeneity, comorbidity burden, or treatment complexity of human sepsis.

Future Directions

Prospective biomarker-guided trials should test whether treatment assignment based on inflammatory phenotype improves survival and reduces treatment-related harm. Future models should incorporate comorbidities, polymicrobial infection, organ support, and longitudinal phenotype transitions.