IntroductionSeptic shock syndrome resulting from excessive host immune responses induced by infectious organisms is a leading cause of death in hospitalized patients. [1][2][3] Pathophysiologic changes in sepsis involve the pathogen-induced uncontrolled release from immune cells, particularly monocytes and macrophages, of proinflammatory mediators. 4 Gram-negative bacterial infection is one of the major causes of systemic bacterial sepsis. 5 Lipopolysaccharide (LPS), a constituent of the Gram-negative outer membrane, is the leading cause of sepsis. LPS induces a rapid increase of proinflammatory mediators, leading to lethal systemic tissue damage and multiple organ failure, which mimics the inflammatory responses of septic syndrome. 6 In mammals, membrane-bound CD14 and toll-like receptor 4 (TLR4)-MD-2 participate in cellular recognition of LPS. 7 Binding of LPS to TLR4 triggers the activation of members of the mitogen-activated protein kinase (MAPK) pathway including p38, p42/p44 extracellular signal-regulated kinase (ERK1/2), and c-Jun N-terminal kinase (JNK). 8 In resting unstimulated cells, nuclear factor-B (NF-B), a heterodimeric complex composed of 50-and 65-kDa (p50/p65) protein subunits, 9 retains as an inactive complex bound to inhibitory B␣ (IB␣) in the cytoplasm. While the cells are under proinflammatory stimulation by LPS, phosphorylation and degradation of IB␣ permit NF-B nuclear translocation and promote the expression of inflammatory genes including inducible nitric oxide synthase (iNOS), tumor necrosis factor-␣ (TNF-␣), and others. 9Thrombomodulin (TM) is a 557 amino acid type I glycosylated transmembrane protein 10 with an NH 2 -terminal lectinlike region (domain 1; D1) followed by 6 epidermal growth factor (EGF)-like structures (domain 2; D2), an O-glycosylation site-rich domain (domain 3; D3), a transmembrane domain (domain 4; D4), and a cytoplasmic tail domain (domain 5; D5). TM domain 2 (TMD2) EGF-like structures are responsible for the anticoagulant activity of TM via the alteration of thrombin substrate specificity. TMD2-thrombin complex sequentially activates anticoagulant protein C inactivating procoagulant cofactors Va and VIIIa. 11 TM expression also occurs in keratinocytes, 12 polymorphonuclear neutrophils (PMNs), 13 monocytes, 14 and endothelial cells, 15 indicating additional functions of TM besides anticoagulation. 16 Indeed TM domains function as an adhesion molecule, 17 an angiogenic factor, 18 and an anti-inflammatory agent through protein C-dependent and -independent mechanisms. 16,19 Recently, anti-inflammatory activity of TM domain 1 (TMD1) was implied by observing that mice with a deleted TM lectinlike domain (TM LeD/LeD ) become more sensitive to LPS challenge through the suppressed expression of adhesion molecules via NFB and MAPK signaling pathways. 20 Moreover, mice with a mutation in the TM gene (TM pro/pro ) strongly reduce the capacity to generate activated protein C, an anti-inflammatory agent in treatment of sepsis. 21 Mice harboring the latter mutation display an u...

Epstein–Barr Virus (EBV) DNase (BGLF5) is an alkaline nuclease and has been suggested to be important in the viral life cycle. However, its effect on host cells remains unknown. Serological and histopathological studies implied that EBV DNase seems to be correlated with carcinogenesis. Therefore, we investigate the effect of EBV DNase on epithelial cells. Here, we report that expression of EBV DNase induces increased formation of micronucleus, an indicator of genomic instability, in human epithelial cells. We also demonstrate, using γH2AX formation and comet assay, that EBV DNase induces DNA damage. Furthermore, using host cell reactivation assay, we find that EBV DNase expression repressed damaged DNA repair in various epithelial cells. Western blot and quantitative PCR analyses reveal that expression of repair-related genes is reduced significantly in cells expressing EBV DNase. Host shut-off mutants eliminate shut-off expression of repair genes and repress damaged DNA repair, suggesting that shut-off function of BGLF5 contributes to repression of DNA repair. In addition, EBV DNase caused chromosomal aberrations and increased the microsatellite instability (MSI) and frequency of genetic mutation in human epithelial cells. Together, we propose that EBV DNase induces genomic instability in epithelial cells, which may be through induction of DNA damage and also repression of DNA repair, subsequently increases MSI and genetic mutations, and may contribute consequently to the carcinogenesis of human epithelial cells.

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