Dengue Protease-Mediated Activation and Polarization of Macrophages

Controlled activation of macrophages to achieve desired phenotypes in vivo and in vitro could lead to possible treatments for several inflammatory and proliferative diseases. This investigation uniquely established that dengue protease enhances the polarization and activation of human and murine macrophages following extracellular exposure. It was observed that macrophages have a robust response to extracellularly administered purified dengue NS2B/NS3 protease; it stimulated the macrophages in classical M1 directions and enhanced both the mitogen-activated protein kinases (MAPK) and c-Jun N-terminal kinases (JNK). The cells exhibited an increase in the intracellular levels of proinflammatory cytokines such as IL-2, IL-6, IL-12, and IFN-{gamma} and an elevation of phosphorylated versions of Akt, P38 MARK, SAPK, and ERK. In tandem, this investigation also established that the heightened responses of stimulated cells were associated with an increase in the cellular reactive oxygen species (ROS) level and the nuclear translocation of the NF-{kappa}B (P65) protein. The cell viability assay showed that NS2B/NS3 protease exerts no major toxic effect on macrophages after 24 hours of treatment, even at a dosage (20 g/ml) which was four times higher than the effective dose (5 g/ml). Remarkably, we also observed that the native form of the viral protease, which drives its enzyme activities, had no bearing on the antigenic qualities of the enzyme. Thus, our study highlighted the efficacy of dengue viral NS2B/NS3 protease as a non-toxic ex vivo macrophage activating/polarizing agent and may serve a vital role in macrophage-based cell therapy in the near future. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=101 SRC="FIGDIR/small/624958v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@d29cd1org.highwire.dtl.DTLVardef@1357e96org.highwire.dtl.DTLVardef@109cc52org.highwire.dtl.DTLVardef@45536b_HPS_FORMAT_FIGEXP M_FIG C_FIG