Nerve Growth Factor Expression and Its Receptors TrkA and p75NTR in Peri-Implantitis Lesions

Background: Nerve growth factor (NGF) can, through its receptors TrkA and p75NTR, convey signals for cell survival or cell differentiation. These proteins are also involved in inflammation and in bone resorption. The aim of this study is to evaluate, for the first time, the expression of NGF and its receptors TrkA and p75NTR in peri-implantitis lesions. Materials and Methods: Fifteen biopsy specimens from patients with chronic peri-implantitis and 4 of healthy oral mucosa were immunostained with antibodies against NGF, TrkA, and p75NTR. The staining intensity and percentage of stained cells were semi-quantitatively evaluated and results were compared between the 2 groups. Results: In the peri-implant pocket epithelium and gingival epithelium, NGF and TrkA expressions were similar to the healthy oral mucosa, however, a decreased expression of p75NTR was observed. In all cases, more than 75% of the inflammatory cells stained positively for NGF and TrkA, and p75NTR was negatively expressed. Conclusion: The intense expression of NGF and TrkA in the inflammatory cell infiltrate associated with decreased expression of p75NTR in both gingival and pocket epithelium suggests that these proteins may have a role in peri-implantitis lesions.