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
Mentions: To test whether PTX3 influences the competition between IαI and HA for TSG-6, we performed another sequential incubation assay (Fig. 6A); here IαI and PTX3 were premixed and then exposed to a TSG-6-loaded HA film (where the TSG-6 had been removed from the bulk solution and the HA-associated protein was beginning to dissociate). Linear fits allowed us to approximate the unbinding rates just before (3.7 ng/cm2/min; green dashed line) and after the addition of IαI/PTX3 (27 ng/cm2/min; red dashed line). Comparison with the displacement induced by IαI alone (Fig. 6B; reproduced from Ref. 45) did not reveal any significant difference. Also, the fraction of stably but non-covalently bound material that persisted after incubation with IαI and PTX3 was comparable with the fraction displaced by IαI alone (30 and 35%, respectively). Hence, PTX3 does not affect the propensity of IαI to displace TSG-6 from HA. More generally, this finding would indicate that PTX3 does not influence the initial interaction between TSG-6 and IαI.
Affiliation: From the CIC biomaGUNE, 20009 Donostia-San Sebastian, Spain.