Anti-inflammatory Protein TSG-6 Promotes Early Gingival Wound Healing: An In Vivo Study

Abstract

Human multipotent mesenchymal stromal cells (hMSCs) produce TNF-α-stimulated gene/ protein 6 (TSG-6). TSG-6, a hyluronan (HA)-binding protein, has been associated with the negative regulation of inflammatory tissue destruction. TSG-6 modulates proinflammatory cytokine cascades and enhances tissue repair. The aim of this study was to test the effects of recombinant human (rh) TSG-6 on the healing of an induced gingival wound within the first 2 days post-surgery.

Following gingival resection in one hundred twenty Sprague-Dawley rats (~400 g), 2 µg recombinant human TSG-6 (rhTSG-6) in 5 µL of Phosphate Buffered Saline (PBS) or the same volume of PBS solution was injected into gingival tissue approximating the surgical wound. Control animals did not receive injections. Examination of animals occurred at 1-2 hrs, 6-8 hrs, 24 hrs, and 48 hrs post-surgery (n= 10 per group). Photographs were taken for a double blind clinical assessment at each time period. Tissue biopsy samples (4mm) and blood were collected at 1-2 hrs, 6-8 hrs, 24 and 48 hrs following surgery. Specimens were analyzed via histological analysis and enzyme-linked immunosorbent assays (ELISA) for quantification and comparison of inflammatory markers IL-1β, IL-6, TNF-α and myeloperoxidase (MPO) per treatment group. Weights were recorded for all animals pre- and post-surgery.

Animals injected with TSG-6 had significantly less severe inflammation based on clinical assessment scores at 6-8 (p=0.01228), 24 (p=0.01675), and 48 hours (p=0.0186). Sham and control animals had more weight loss at 24 and 48 hours. Based on histological analysis, sham and control animals had more pronounced cellular infiltrate. Animals injected with TSG-6 had significantly less myeloperoxidase (MPO) (p=0.027) at 24 hours and IL-1β (p=0.027) at 24 & 48 hours. IL-6 showed marginal significant difference at 6-8 hours. There was no significant difference for TNF-α at any time point.

TSG-6 reduced post-operative gingival inflammation by modulating the inflammatory cascade; reducing levels of proinflammatory cytokines and cellular infiltrate. Gingival injection of TSG-6 may offer significant promise as an anti-inflammatory agent for patients requiring gingival surgery.