Objective To study the effect of bacterial infection on the formation of capsular contracture after breast prosthesis implantation.

Methods A mouse model of silicone implant breast prosthesis was established. The experimental group was injected with bacterial lipoteichoic acid (LTA) and the control group was injected with normal saline. The tissue structure, the thickness of fibrous capsule and the degree of fibrosis reaction around the implant were observed by Masson and enzyme immunohistochemical staining. The number of neovascularization was counted by CD31 staining. The mRNA level of inflammatory factor was measured by quantitative PCR. The number of proliferative/apoptotic cells was counted by Ki-67/Caspase-3 staining.

Results In the saline injected group, a thin blue fibrous capsule was formed around the implant; compared with saline injected group, the thickness of fibrous capsule around the implant increased by (1.3±0.08) times (P < 0.05) in the bacterial LTA injection group, presenting blue and red. The area of α-SMA increased by (12.38±0.91) times (P < 0.05). The number of neovascularization increased (P < 0.05). The levels of IL-6 and TNF-α mRNA increased (P < 0.05), whereas the level of IFN-γ mRNA did not change, mRNA level of TLR2 increased (P < 0.05). The number of Ki-67 or Caspase-3 positive cells increased (P < 0.05).

Conclusions The fibrosis response, the fibrous capsule thickness, and the degenerated connective tissue content increase around the implant after multiple local injections of bacterial LTA. The number of neovascularization, proliferating, apoptotic cells, and the mRNA levels of related inflammatory factors and TLR2 increase too.