Role of Toll-like receptor 4 in the inflammation reaction surrounding silicone prosthesis

Toll-Like Receptor 4 Expression in Human Breast Implant Capsules

“…39 With regard to capsules surrounding silicone implants, Auquit-Auckbur and colleagues found that those harvested from toll-like receptor 4-null mice presented underexpression of vascular endothelial growth factor and TGF-β1, and lower inflammatory infiltrate, number of vessel sections, and thickness compared with control specimens. 20 Our study, instead, investigated toll-like receptor 4 expression in human samples, finding that, besides inflammatory cells, it was expressed by fibroblasts and myofibroblasts of breast implant capsules. The endogenous ligands, which are also available in sterile conditions, may directly act on these cells by binding to toll-like receptor 4, thus promoting myofibroblast differentiation, and TGF-β, vascular endothelial growth factor, and collagen production.…”

“…33,34 Moreover, they also recognize several endogenous ligands produced by damaged tissues, 33 such as heat shock proteins, alternatively spliced fibronectin extradomain, tenascin C, biglycan, oligosaccharides of hyaluronic acid, heparin sulphate, fibrinogen, and nucleic acids released from necrotic cells. 13,20 As a consequence, toll-like receptors act as inflammatory modulators during both sterile and nonsterile wound healing processes, with evidence suggesting their role as a sensitive detection system to initiate tissue repair after injury. 9,35 Among these, toll-like receptor 4 is involved in a variety of fibrotic processes in kidney, 36 liver, 37,38 and skin.…”

“…The reaction against the foreign body implies the initial recruitment of polymorphonuclear cells and macrophages, followed by giant cell formation and fibroblast proliferation to encapsulate the implant. 20,21 For a long time, fibroblasts were considered responsible for the production of extracellular matrix only. In the past two decades, this assumption has changed radically: these cells may exert a direct and active immunoregulatory role in both physiologic and pathologic immune responses.…”

“…The endogenous ligands, which are also available in sterile conditions, may directly act on these cells by binding to toll-like receptor 4, thus promoting myofibroblast differentiation, and TGF-β, vascular endothelial growth factor, and collagen production. 11,14,20 We also focused on the possible relationship between this receptor and estrogen receptor expression. 17β-Estradiol increased cell surface toll-like receptor 4 expression and toll-like receptor 4-triggered proinflammatory mediator production by murine macrophages in vivo.…”

Definition of Inflammation, Causes of Inflammation and Possible Anti-inflammatory Strategies

“…The principal cause of inflammation is a pure mechanical pressure, including blunt trauma [103,104], foreign bodies [105,106], vibrations [107,108] and chronic pressure of low intensity [109,110]. The basic mechanism of causing inflammation by pressure is most probably through tissue hypoxia.…”