Chimeric IL-6/4R-LL37 Engineered Macrophages Achieve Synchronized Inflammation Control and Antimicrobial Defence in Sepsis.

Summary

The investigators developed macrophages engineered to deliver an IL-6/4 fusion protein and LL37 antimicrobial peptide mRNA through an in situ lipid nanoparticle platform. In mouse sepsis models, the therapy improved survival, reduced organ damage and bacterial burden, and restored T-cell and macrophage functions, addressing both hyperinflammation and persistent immunosuppression.

Key Findings

• IL-6/4 fusion signaling was designed to inhibit IL-6-driven inflammation while promoting IL-4-associated anti-inflammatory and tissue-repair pathways.
• LL37 antimicrobial peptide delivery reduced bacterial burden and contributed to antimicrobial defense.
• Engineered macrophages improved survival, histopathology, organ bacterial burden, and T-cell and macrophage functional recovery in septic mice.

Clinical Implications

The approach could eventually support precision immunotherapy for patients with simultaneous cytokine-driven injury and immunosuppression. However, safety, biodistribution, manufacturing consistency, off-target immune effects, and efficacy in clinically representative large-animal models must be established before human trials.

Limitations

• The evidence is limited to preclinical sepsis models, and human pharmacology, toxicity, and feasibility remain untested.
• The abstract does not establish whether efficacy is preserved across different pathogens, infection sources, disease severities, or treatment windows.

Future Directions

Future work should define the optimal cellular product, dosing and timing, assess long-term immunological and oncological safety, test efficacy in polymicrobial and pathogen-specific models, and conduct good-manufacturing-practice development before first-in-human studies.