Ecotin, a microbial inhibitor of serine proteases, blocks multiple complement dependent and independent microbicidal activities of human serum.

Ecotin is a serine protease inhibitor produced by hundreds of microbial species, including pathogens. Here we show, that ecotin orthologs from Escherichia coli, Yersinia pestis, Pseudomonas aeruginosa and Leishmania major are potent inhibitors of MASP-1 and MASP-2, the two key activator proteases of the complement lectin pathway. Factor D is the key activator protease of another complement activation route, the alternative pathway. We show that ecotin inhibits MASP-3, which is the sole factor D activator in resting human blood. In pathway-specific ELISA tests, we found that all ecotin orthologs are potent lectin pathway inhibitors, and at high concentration, they block the alternative pathway as well. In flow cytometry experiments, we compared the extent of complement-mediated opsonization and lysis of wild-type and ecotin-knockout variants of two E. coli strains carrying different surface lipopolysaccharides. We show, that endogenous ecotin provides significant protections against these microbicidal activities for both bacteria. By using pathway specific complement inhibitors, we detected classical-, lectin- and alternative pathway-driven complement attack from normal serum, with the relative contributions of the activation routes depending on the lipopolysaccharide type. Moreover, in cell proliferation experiments we observed an additional, complement-unrelated antimicrobial activity exerted by heat-inactivated serum. While ecotin-knockout cells are highly vulnerable to these activities, endogenous ecotin of wild-type bacteria provides complete protection against the lectin pathway-related and the complement-unrelated attack, and partial protection against the alternative pathway-related damage. In all, ecotin emerges as a potent, versatile self-defense tool that blocks multiple antimicrobial activities of the serum. These findings suggest that ecotin might be a relevant antimicrobial drug target.

Dysregulation of microRNA expression in human cervical preneoplastic and neoplastic lesions.

Data discussed in recent reviews demonstrated that dysregulation of microRNA (miRNA) expression profiles occurs during cervical carcinogenesis and characteristic up- or downregulation of certain miRNAs might be used as biomarkers. The majority of altered miRNAs, however were found to be inconsistent upon comparison with cancerous and normal cervical epithelia in the discussed studies due to several reasons. The results obtained in this present review suggest the need for further investigations on miRNAs on larger sample sizes in order to indicate sensitivity and specificity by means of well defined, "unified" methods. In addition, obtaining further data on the clinical course and outcome of patients in comparison to the dysregulation of miRNA expression profile could turn miRNAs into prognostic and/or progression markers. Inhibition of overexpressed miRNAs, as suggested by some authors, might even serve as target for cancer therapy.