Innsbruck, Austria — Researchers at the Innsbruck Medical University have released results of a study aimed at identifying proteins that adsorb to the surface of silicone and have been long regarded as key components in the onset and perpetuation of local immune reactions to the implant material.
The study identifies 30 of the most abundant proteins deposited on the surface of silicone — the largest known inventory of such proteins so far, write the study’s authors. Structural and extracellular matrix proteins predominated, followed by mediators of host defense, metabolism, transport, and stress-related proteins. In addition, several biochemical modifications of fibronectin, vitronectin and heat-shock protein 60 were detected. The research team’s analyses also showed previously undetected proteins deposited on the surface of silicone, and concluded that as tentative initiators and/or modulators of the response to silicone, they are valuable candidates for prognosis and therapy.
The researchers note that because of its “assumed high degree of biocompatibility,” silicone is the most widely used implant material, even though its use can have detrimental side effects in many patients. The study sought to more thoroughly understand the extent to which certain proteins adsorb to implants because, as the study notes, “the composition of the proteinaceous film on the surface of silicone implants is poorly understood, especially in vivo.”
The study focused on 23 healthy women undergoing breast augmentation; 13 patients were having implants removed or replaced due to fibrotic complications, while 10 (the control group) were undergoing primary breast augmentation. No difference in protein deposition was observed between gel- or saline-filled implants, and no correlation in relative protein amount was found with regard to implant size or surface texture. In implants of more than five years duration, however, the amount of protein deposited on the surface was significantly higher than those in place for shorter periods.
The study concludes that previously undetected proteins deposited on the surface of silicone are tentative initiators and/or modulators of the response to silicone, and that they are valuable candidates for disease prevention, therapy, and as a parameter to assessing silicone’s biocompatibility. The study’s authors note that, while the causative relation between autoimmune-disease development and silicone implants is still a matter of debate, their study shows that silicone promotes at least the adhesion of altered self-proteins, which in turn may trigger an autoimmune response of the immune system.