Neutrophils show chemotaxis to type IV collagen and its 7S domain and contain a 67 kD type IV collagen binding protein with lectin properties.

Neutrophils were found to demonstrate chemotactic responses to pepsinized human placental type IV collagen and its purified aminoterminal 7S domain. The maximal chemotactic responses occur at approximately 400 ng/ml and approximately 30 ng/ml of type IV collagen and 7S collagen, respectively, and are similar in magnitude to the chemotactic response of neutrophils to 10(-8) M FMLP. Human leukemic cells of the HL 60 line display chemotaxis to type IV collagen and 7S collagen only after they are differentiated along the neutrophilic pathway with dimethyl sulfoxide. When detergent extracts of neutrophils are applied to type IV collagen-Affi-Gel resin, a 67 kD protein is retained by the resin and is eluted with guanidine/octyl-beta-glucoside or lactose. This 67 kD polypeptide has an amino acid composition resembling the 67 kD component of the elastin receptor complex, displays immunologic cross-reactivity with antibody to the 67 kD component of the elastin receptor, and binds to elastin and laminin affinity resins. Neutrophil chemotaxis to type IV collagen and 7S collagen is selectively abolished by exposing the test neutrophils to lactose or elastin peptides. We conclude that neutrophils may migrate in vivo to proteolytic fragments of type IV collagen and that this response may be mediated by a lectin-like protein that is similar to the 67 kD component of the elastin receptor.

Degradation of native type IV procollagen by human neutrophil elastase. Implications for leukocyte-mediated degradation of basement membranes.

Leukocyte-derived proteases may contribute to the destruction of basement membranes during inflammation. We have, therefore, examined the degradation of human type IV procollagen (PC) by purified human neutrophil elastase (HLE). Native [14C]proline-labeled type IV PC was isolated from cultures of human HT-1080 cells and incubated with HLE for various times at 25 or 37 degrees C. Cleavage products were resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and identified by CNBr peptide mapping. Incubation of type IV PC with HLE (less than 1:10 HLE:type IV weight ratio) resulted in cleavage of the pro alpha 1 (IV) and pro alpha 2 chains (Mr 180,000 and 175,000) to discrete components of Mr greater than 140,000. Peptide mapping indicated that the carboxy-terminal collagenase-resistant domains of both chains were rapidly and preferentially degraded. Longer incubations or incubations at higher enzyme:substrate ratios resulted in extensive and asymmetric internal cleavage with the generation of fragments similar in size distribution to the major pepsin-resistant fragments of type IV collagen. Our findings indicate that soluble, native human type IV PC is a substrate for HLE and is preferentially cleaved within the globular carboxy-terminal domains of the pro alpha 1 and pro alpha 2 chains. We suggest that even limited cleavage of type IV PC by HLE may disrupt intermolecular carboxy-terminal interactions believed to be important for basement membrane assembly and for maintaining basement membrane structure in vivo.