Nasal carriage of Staphylococcus aureus has been identified as a risk factor for community-acquired and nosocomial infections. We screened 230 donors of diverse ethnic and socioeconomic backgrounds and identified 62 (27%) whose nasal secretions were colonized by S. aureus. In 18 donors in whom the various regions of the nasal luminal surface were separately sampled, the predominant region of S. aureus colonization was the moist squamous epithelium on the septum adjacent to the nasal ostium. Nasal fluid from carriers was defective in killing endogenous S. aureus and nasal carrier isolates of S. aureus but not a laboratory S. aureus strain. Transmission electron microscopy revealed that S. aureus isolates incubated in nasal fluid from carriers for 2 h at 37°C were less damaged than those incubated in noncarrier fluid and were coated with an electron-dense layer. Compared with that from healthy donors and patients with acute rhinitis, nasal fluid from carriers contained elevated concentrations of the neutrophil-derived defensins human neutrophil peptides 1 to 3 (47-and 4-fold increases, respectively), indicative of a neutrophil-mediated inflammatory host response to S. aureus colonization. The concentration of the inducible epithelial antimicrobial peptide human ␤-defensin 2 was also highly elevated compared to that in healthy donors, in whom the level was below the detection limit, or patients with acute rhinitis (sixfold increase). Thus, nasal carriage of S. aureus takes hold in nasal fluid that is permissive for colonization and induces a local inflammatory response that fails to clear the colonizing bacteria.Nasal Staphylococcus aureus carriage, affecting about 20% of the population, has been identified as a risk factor for the pathogenesis of community-acquired and nosocomial infections (5, 12). The factors that determine carrier or noncarrier status are largely unknown. Various epithelial and mucous host factors, such as surface glycoproteins and proteoglycans, have been shown to mediate the binding of S. aureus, but the precise adhesive molecules on the host and bacteria have not been identified. S. aureus appears to attach to cell-associated and cell-free secretions (10) and to interact with receptor sites of secretory immunoglobulin A (1), glycolipids (6), and surfactant protein A (8). Various bacteria, including Staphylococcus epidermidis, are capable of reducing nasal ciliary activity in vitro (4). Enhanced adhesion and diminished mucociliary clearance could explain the retention of S. aureus within the nasal passageways but not its ability to grow to a high density in this normally nonpermissive environment.Recent studies have highlighted the innate antimicrobial properties of nasal fluid (2) and airway fluid in general (11). The current study explored the factors that contributed to S. aureus colonization in a cohort of donors with nasal S. aureus carriage. MATERIALS AND METHODSIdentifying carriers of S. aureus. Samples of nasal flora and nasal fluid were collected from healthy volunteer donors accordi...

The human airways are protected from pathogenic colonization by a blanket of fluid impregnated with innate antimicrobial effector molecules. Among several previously uncharacterized components, we isolated a peptide that had activity primarily targeting Gram-negative bacteria. We named the peptide`calcitermin' since its amino acid sequence and mass were equivalent to the 15 C-terminal residues of the S100 protein, calgranulin C. The antimicrobial activity of calcitermin was enhanced in acidic buffers (pH 5.4) and in the presence of micromolar concentrations of ZnCl 2 . Analysis revealed a putative zinc-binding consensus sequence as well as an K K-helical conformation in structure-promoting solvents. ß

Type VII collagen, the major component of anchoring fibrils, consists of a central collagenous triple-helical domain flanked by two noncollagenous domains, NC1 and NC2. The NC2 domain has been implicated in catalyzing the antiparallel dimer formation of type VII procollagen. In this study, we produced the entire 161 amino acids of the NC2 domain plus 186 amino acids of adjacent collagenous domain (NC2/COL) and purified large quantities of the recombinant NC2/COL protein. Recombinant NC2/ COL readily formed disulfide-bonded hexamers, each representing one antiparallel dimer of collagen VII. Removal of the collagenous helical domain from NC2/COL by collagenase digestion abolished the antiparallel dimer formation. Using site-directed mutagenesis, we found that mutation of either cysteine 2802 or cysteine 2804 alone within the NC2 domain blocked antiparallel dimer formation. In contrast, a single cysteine mutation, 2634, within the collagenous helical domain had no effect. A generated methionine to lysine substitution, M2798K, that is associated with recessive dystrophic epidermolysis bullosa, was unable to form antiparallel dimers. Furthermore, autoantibodies from epidermolysis bullosa acquisita patients also reacted with NC2/COL. We conclude that NC2 and its adjacent collagenous segment mediate antiparallel dimer formation of collagen VII. Epidermolysis bullosa acquisita autoantibodies bound to this domain may destabilize anchoring fibrils by interfering with antiparallel dimer assembly leading to epidermal-dermal disadherence.Type VII collagen, a genetically distinct member of the collagen family, is found within the basement membrane zone beneath stratified squamous epithelium (1, 2). Type VII collagen is a major component of anchoring fibrils, attachment structures within the basement membrane between the epidermis and dermis of human skin (3, 4). In inherited forms of dystrophic epidermolysis bullosa (DEB), 1 anchoring fibrils are diminutive and/or reduced in number (5-7). In addition to inherited DEB, epidermolysis bullosa acquisita (EBA) is an acquired autoimmune form of epidermolysis bullosa. EBA is characterized by circulating and tissue-bound IgG autoantibodies to type VII collagen (8, 9). Like DEB, ultrastructural studies have demonstrated a dramatic paucity of anchoring fibrils in EBA skin (10). These observations suggest that type VII collagen plays an important role in maintaining epidermal-dermal adherence. Type VII collagen has been cloned, and a genetic linkage has been established between inherited DEB and mutations in the gene that encodes for type VII collagen, COL7A1 (11-14). There have been over 100 distinct COL7A1 gene mutations identified in patients with DEB, and these mutations have occurred within NC1, NC2, and the helical domain (15,16).Type VII collagen is composed of three identical ␣ chains, each consisting of a 145-kDa central collagenous triple-helical segment, flanked by a large 145-kDa amino-terminal non-collagenous domain (NC1), and a smaller 34-kDa carboxyl-terminal non-collagen...