Gene transfer with IL-4 and IL-13 improves survival in lethal endotoxemia in the mouse and ameliorates peritoneal macrophages immune competence

Apoptotic cells suppress mast cell inflammatory responses via the CD300a immunoreceptor

After cecal ligation and puncture, mice lacking the phosphatidylserine receptor CD300a on mast cells show more neutrophil recruitment to the peritoneal cavity, improved bacterial clearance, and extended survival.

When a cell undergoes apoptosis, phosphatidylserine (PS) is exposed on the outer leaflet of the plasma membrane. PS acts as an “eat-me” signal to direct phagocytes expressing PS receptors to engulf the apoptotic cell. We recently reported that the immunoreceptor CD300a, which is expressed on myeloid cells, is a PS receptor. We show that CD300a does not facilitate macrophage phagocytosis of apoptotic cells. Instead, CD300a delivers an inhibitory signal in mast cells to suppress production of LPS-induced inflammatory cytokines and chemokines. After cecal ligation and puncture (CLP), when a large number of cells undergo apoptosis in the peritoneal cavity, CD300a-deficient peritoneal mast cells produced more chemoattractant and recruited more neutrophils than did wild-type (WT) mast cells. As a result, CD300a-deficient mice showed increased neutrophil recruitment and improved bacterial clearance in the peritoneal cavity, and survived longer than WT mice. Antibody blockade of CD300a–PS interactions improved bacterial clearance and extended survival of WT mice subjected to CLP. These results indicated that CD300a is a nonphagocytic PS receptor that regulates mast cell inflammatory responses to microbial infections.

Comparison between intravenous and peritoneal route on liver targeted uptake and expression of plasmid delivered by Glyco-poly-L-lysine

AIM: To compare the effects of intravenous route and peritoneal route on liver targeted uptake and expression of plasmid delivered by galactose-terminal glyco-poly-L-lysine (G-PLL).

METHODS: The plasmid pTM/MMP-1 which could be expressed in eukaryotic cells was bound to G-PLL, and was then transferred into Wistar rats by intra venous and intraperitoneal injection. The expression and distribution of the plasmid were observed at different time periods by in situ hybridization and im munohistochemistry.

RESULTS: The plasmid could be expressed significantly within 24 h a fter being transferred in vivo by both intravenous and intraperitoneal routes. One week later the expression began to decrease, and could still be observed three weeks later. Although both the intravenous and intraperitoneal route could target-specifically deliver the plasmid to the liver, the effect of the former was better as compared to that of the latter.

CONCLUSION: Intravenous route is better for liver targeted uptake and expression of G-PLL-bound plasmids than the peritoneal route.