Global analysis of community-associated methicillin-resistant Staphylococcus aureus exoproteins reveals molecules produced in vitro and during infection

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is a threat to human health worldwide. Although progress has been made, mechanisms of CA-MRSA pathogenesis are poorly understood and a comprehensive analysis of CA-MRSA exoproteins has not been conducted. To address that deficiency, we used proteomics to identify exoproteins made by MW2 (USA400) and LAC (USA300) during growth in vitro. Two hundred and fifty unique exoproteins were identified by 2-dimensional gel electrophoresis coupled with automated direct infusion-tandem mass spectrometry (ADI-MS/MS) analysis. Eleven known virulence-related exoproteins differed in abundance between the strains, including alpha-haemolysin (Hla), collagen adhesin (Cna), staphylokinase (Sak), coagulase (Coa), lipase (Lip), enterotoxin C3 (Sec3), enterotoxin Q (Seq), V8 protease (SspA) and cysteine protease (SspB). Mice infected with MW2 or LAC produced antibodies specific for known or putative virulence factors, such as autolysin (Atl), Cna, Ear, ferritin (Ftn), Lip, 1-phosphatidylinositol phosphodiesterase (Plc), Sak, Sec3 and SspB, indicating the exoproteins are made during infection in vivo. We used confocal microscopy to demonstrate aureolysin (Aur), Hla, SspA and SspB are produced following phagocytosis by human neutrophils, thereby linking exoprotein production in vitro with that during host–pathogen interaction. We conclude that the exoproteins identified herein likely account in part for the success of CA-MRSA as a human pathogen

Truncated active matrix metalloproteinase-8 gene expression in Hepg2 cells is active against native type I collagen

Background/Aims: Excess type I collagen accumulation is a major feature of fibrotic diseases such as liver cirrhosis. Reversion of this disease has not been fully accomplished. Pbysiologically, collagen is degraded by interstitial collagenases, neutrophil collagenase (MMP-8) being the most active against type I collagen. Introduction of MMP-8 gene into liver cells could be an advantageous tool to potentiate fibrosis degradation. Methods: We cloned latent and active MMP-8 genes in prokaryotic and eukaryotic expression vectors and an adenoviral vector. Transfection of MMP-8 in HepG2 was effectuated by CaPO4, polylysine-lactose (P-L) and adenoviral transduction, and cells and culture supernatant were harvested 72 h after transfection for analysis of MMP-8 expression by reverse transcription-polymerase chain reaction and collagenolytic activity. Results and Conclusions: We show that a truncated neutrophil collagenase (tMMP-8) backing a portion of the carboxy terminus and with an intact aminoterminus (latent; l-tMMP-8) or a truncated amino terminus (active; a-tMMP-8) has enzymatic activity against native type I collagen, and the activity was inhibited by EDTA, 1,10-phenanthroline and TIMP-1. Both MMP-8 mRNA (latent and active) were detected by polymerase chain reaction in cells transfected with CaPO4, P-L and adenoviral transduction; however, relative expression of MMP-8 was enhanced when the plasmid was delivered as a P-L complex and increased by adenoviral infection. Finally, a-tMMP-8 cDNA was cloned in a vector under transcriptional control of a reguiated promoter (PEPCK-a-tMMP-8). HepG2 cells, transfected with the PEPCK-a-tMMP-8 plasmid DNA up-regulated expression of: A-tMMP-8 after incubation of the cells with butyryl-cAMP and glucagon, while stimulation with insulin slightly down-regulated its expression. Recombinant MMP-8 expressed by HepG2-transduced cells can efficiently degrade soluble type I collagen, which is potentially useful for gene transfer therapies