Inhibition of Autolysis by Lipase LipA in Streptococcus pneumoniae Sepsis.

More than 50% of sepsis cases are associated with pneumonia. Sepsis is caused by infiltration of bacteria into the blood via inflammation, which is triggered by the release of cell wall components following lysis. However, the regulatory mechanism of lysis during infection is not well defined. Mice were infected with Streptococcus pneumoniae D39 wild-type (WT) and lipase mutant (ΔlipA) intranasally (pneumonia model) or intraperitoneally (sepsis model), and survival rate and pneumococcal colonization were determined. LipA and autolysin (LytA) levels were determined by qPCR and western blotting. S. pneumoniae Spd_1447 in the D39 (type 2) strain was identified as a lipase (LipA). In the sepsis model, but not in the pneumonia model, mice infected with the ΔlipA displayed higher mortality rates than did the D39 WT-infected mice. Treatment of pneumococci with serum induced LipA expression at both the mRNA and protein levels. In the presence of serum, the ΔlipA displayed faster lysis rates and higher LytA expression than the WT, both in vitro and in vivo. These results indicate that a pneumococcal lipase (LipA) represses autolysis via inhibition of LytA in a sepsis model.

Antistress effect of red ginseng in brain cells is mediated by TACE repression via PADI4.

Ginseng is known to have antistress effects. Previously, red ginseng (RG) was shown to repress stress-induced peptidyl arginine deiminase type IV (PADI4) via estrogen receptor ß (ERß) in the brain, thus inhibiting brain cell apoptosis. Moreover, tumor necrosis factor (TNF)-α plays a critical role in immobilization (IMO) stress. However, the signaling pathway of RG-mediated repressesion of inflammation is not completely understood. In this study, we determined how RG modulated gene expression in stressed brain cells. Since secretion of TNF-α is modulated via TNF-α converting enzyme (TACE) and nuclear factor (NF)-κB, we examined the inflammatory pathway in stressed brain cells. Immunohistochemistry revealed that TACE was induced by IMO stress, but RG repressed TACE induction. Moreover, PADI4 siRNA repressed TACE expression compared to the mock transfected control suggesting that PADI4 was required for TACE expression. A reporter assay also revealed that H2O2 oxidative stress induced NF-κB in neuroblastoma SK-N-SH cells, however, RG pretreatment repressed NF-κB induction. These findings were supported by significant induction of nitric oxide and reactive oxygen species (ROS) by oxidative stress, which could be repressed by RG administration. Taken together, RG appeared to repress stress-induced PADI4 via TACE and NF-κB in brain cells thus preventing production of ROS and subsequently protecting brain cells from apoptosis.

Anti-oxidative stress effect of red ginseng in the brain is mediated by peptidyl arginine deiminase type IV (PADI4) repression via estrogen receptor (ER) ß up-regulation.

AIM OF THE STUDY: Ginseng has been used as an anti-stress agent, and its active ingredient, ginsenoside, is similar in structure to estrogen. However, the effect of ginseng on the stressed brain is not completely understood. The aim of this study is to understand systematically how red ginseng (RG) affects gene expressions in the brain of immobilization (IMO) stressed mice to elucidate its underlying mechanism. MATERIALS AND METHODS: For in vivo experiments, mice were stressed by immobilization for 30, 45, or 60 min, and gene expression in the mice brain was analyzed by microarray and system biology. Apoptosis was measured by terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick-end labeling (TUNEL) staining, and gene expression by Western blot or qPCR. For in vitro study, the SK-N-SH neuroblastoma cells were stressed by H2O2 exposure. The resultant cytotoxicity was measured by MTT assay, and gene expression by Western blot, ELISA, or qPCR. RESULTS: Microarray analysis of genes in IMO stressed mice brains showed that RG administration prior to IMO stress downregulated >40 genes including peptidyl arginine deiminase type 4 (PADI4). Interestingly, PADI4 was up-regulated by various stresses such as H2O2, acrylamide, and tunicamycin in neuroblastoma SK-N-SH cells but inhibited by RG. IMO stress and in vitro H2O2 stress depressed the estrogen receptor (ER)-ß expression but not ERα. However, RG treatment increased ERß expression both in vivo and in vitro. Comparative analysis regarding the networks by systems biology revealed that TNF-α plays a critical role in IMO stress, and the cell death associated network was much higher than other categories. Consistently, the IMO stress induced TNF-α and Cox-2 expressions, malondialdehyde (MDA), and cell death in the brain, whereas RG administration inhibited these inductions in vivo. siRNA and transient expression studies revealed that ERß inhibited the PADI4 expression. CONCLUSION: PADI4 could be used as an oxidative stress marker. RG seems to inhibit oxidative stress-inducible PADI4 by up-regulating ERß expression in the brain thus protecting brain cells from apoptosis.