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: Surprisingly, PTX3 did not show any measurable binding if the HA film was preloaded with full-length TSG-6 instead of Link_TSG6. Consistent with this, subsequent incubation with the MNB4 antibody, which recognizes the N-terminal domain of PTX3, did not lead to any increase in binding signal (i.e. it did not appreciably affect the rhTSG-6 unbinding curve) (Fig. 2B). However, from Fig. 1, D and E, as well as previous reports (12, 30, 60), we know that rhTSG6 can interact with PTX3 in the absence of HA. Thus, it would appear that the interaction of rhTSG-6 with PTX3 is perturbed by HA. To shed light on this, we performed binding assays in which the HA film was exposed to a constant amount of PTX3, along with increasing concentrations of either Link_TSG6 (Fig. 3A) or rhTSG-6 (Fig. 3B). For comparison, both TSG-6 constructs were also titrated into the HA film in the absence of PTX3 and were found to exhibit distinct binding (Fig. 3), as has been noted previously (40); binding of rhTSG-6 to HA is characterized by a pronounced positive cooperativity, and the K0.5 is about 5-fold lower than for Link_TSG6.
Affiliation: From the CIC biomaGUNE, 20009 Donostia-San Sebastian, Spain.