Ameliorative effects of traditional Chinese medicine formula NRICM101 on periodontal inflammation: In vitro and in vivo

Introduction: Taiwan Chingguan Yihau (NRICM101) is a novel anti-inflammatory traditional Chinese medicine formula developed in 2020 for COVID-19 pandemic. This study aimed to evaluate the effect of NRICM101 on periodontal inflammation, using human gingival fibroblasts (HGFs) exposed to Porphyromonas gingivalis lipopolysaccharide (Pg LPS) and rat models of ligature-induced periodontitis. Methods: In vitro, HGFs were stimulated with Pg LPS and NRICM101. Cell viability and the expression of pro-inflammatory cytokines, including interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and IL-1β were measured using MTS assay and reverse transcription quantitative polymerase chain reaction (RT-qPCR). In vivo, Sprague-Dawley rats were divided into control, ligature placement, and NRICM101 treatment groups. Ligature placement was performed at day one and oral administration of NRICM101 (50 or 100 mg/kg body weight/day) or saline began one day prior to ligation and the following days. On day 8, the rats were sacrificed, periodontal tissue specimens were analyzed using microcomputed tomography (Micro-CT) imaging, RT-qPCR, and immunohistochemical (IHC) staining to evaluate the effects of the treatments. Results: NRICM101 reduced HGFs viability above 1.0 mg/mL, while Pg LPS caused similar effects at concentrations above 1.0 μg/mL. Co-treatment with Pg LPS (0.5–1.0 μg /mL) and NRICM101 (0.1–0.5 mg/mL) showed no cytotoxicity. In vivo, NRICM101 attenuated alveolar bone loss and significantly decreased IL-6, TNF-α, and partially IL-1β expression, as confirmed by micro-CT, RT-qPCR, and IHC analyses. Discussion: This study demonstrates that NRICM101 exerts protective anti-inflammatory effects in both cellular and animal models of periodontitis. It suppressed pro-inflammatory cytokine expression in HGFs and mitigated alveolar bone loss in ligature-induced periodontitis rats. The effects on IL-6 and TNF-α were pronounced, while the partial reduction of IL-1β may reflect additional regulatory mechanisms such as inflammasome activation, which warrants further investigation. These findings indicate that NRICM101 reduces inflammation without cytotoxicity and supports its potential application in managing chronic periodontal inflammation.