Reduced NLRP3 Gene Expression Limits the IL-1 Cleavage via Inflammasome in Monocytes from Severely Injured Trauma Patients.

OBJECTIVE

Traumatic injury or severe surgery leads to a profound immune response with a diminished functionality of monocytes and subsequently their IL-1 release. IL-1 plays an important role in host immunity and protection against infections. Its biological activation via IL-1-precursor processing requires the transcription of inflammasome components and their activation. Deregulated activity of NOD-like receptor inflammasomes (NLR) like NLRP3 that leads to the maturation of IL-1 has been described in various diseases. While the role of other inflammasomes has been studied in monocytes, nothing is known about NLRP3 inflammasome after a traumatic injury. Here, the role of the NLRP3 inflammasome in impaired monocyte functionality after a traumatic injury was analyzed.

MEASUREMENTS AND MAIN RESULTS

Ex vivo- stimulation of isolated CD14 monocytes with lipopolysaccharide (LPS) showed a significantly higher IL-1 secretion in healthy volunteers (HV) compared to trauma patients (TP) after admission. Reduced IL-1 secretion was paralleled by significantly lowered gene expression of NLRP3 in monocytes from TP compared to those of HV. Transfection of monocytes with NLRP3-encoding plasmid recovered the functionality of monocytes from TP regarding the IL-1 secretion.

CONCLUSIONS

This study demonstrates that CD14 monocytes from TP are significantly diminished in their function and that the presence of NLRP3 components is necessary in recovering the ability of monocytes to produce active IL-1. This recovery of the NLRP3 inflammasome in monocytes may imply a new target for treatment and therapy of immune suppression after severe injury.