Incorporation of pentraxin 3 into hyaluronan matrices is tightly regulated and promotes matrix cross-linking.
Bottom Line: We found that PTX3 binds neither to HA alone nor to HA films containing TSG-6.Interestingly, prior encounter with IαI was required for effective incorporation of PTX3 into TSG-6-loaded HA films.We propose that this mechanism is essential for correct assembly of the COC matrix and may also have general implications in other inflammatory processes that are associated with HA cross-linking.
Affiliation: From the CIC biomaGUNE, 20009 Donostia-San Sebastian, Spain.Show MeSH
Related in: MedlinePlus
Mentions: The absence of PTX3 binding in the above-described assays disproves existing hypotheses about the mechanism by which PTX3 is incorporated into HA matrices (12, 48). On the other hand, PTX3 has been shown to be an essential component in the formation of the COC matrix (12). So how is PTX3 incorporated into HA films? We hypothesized that PTX3 must encounter IαI and/or TSG-6 prior to interaction with HA in order for PTX3 to be incorporated into HA assemblies. To test this hypothesis, we first added PTX3 and IαI at bulk concentrations of 0.3 and 1 μm, respectively, to an HA film. As anticipated, this mixture did not show any HA binding activity (Fig. 1C) (45). Second, TSG-6 was added at a bulk concentration of 0.3 μm. This protein did start a binding reaction (Fig. 5A). After 2 h of incubation, all proteins in the soluble phase were removed. Following this, the anti-PTX3 antibody (MNB4) did bind to the film. In contrast, the same antibody did not bind to an HA film that contained TSG-6 (Fig. 2B). This provides strong evidence that co-incubation of PTX3 in a ternary mixture with IαI and TSG-6 promotes PTX3 incorporation into the HA film.
Affiliation: From the CIC biomaGUNE, 20009 Donostia-San Sebastian, Spain.