Wnt7B enhances the osteogenic differentiation of lipopolysaccharide-stimulated human periodontal ligament stem cells and inhibits the M1 polarization of macrophages by binding FZD4

Periodontitis, a common oral disease characterized by the progressive infiltration of bacteria, is a leading cause of adult tooth loss. Periodontal stem cells (PDLSCs) possess good self‑renewal and multi‑potential differentiation abilities to maintain the integrity of periodontal support structure and repair defects. The present study aimed to analyze the roles of Wnt7B and frizzled4 (FZD4) in the osteogenic differentiation and macrophage polarization during periodontitis using an <i>in vitro</i> cell model. First, Wnt7B expression in the periodontitis‑affected gingival tissue of patients and lipopolysaccharide (LPS)‑stimulated PDLSCs was assessed using the GSE23586 dataset and western blot analysis, respectively. In Wnt7B‑overexpressing PDLSCs exposed to LPS, the capacity of osteogenic differentiation was evaluated by detecting alkaline phosphatase activity, the level of Alizarin Red S staining and the expression of genes related to osteogenic differentiation. Subsequently, conditioned medium from PDLSCs overexpressing Wnt7B was used for M0 macrophage culture. The expression of CD86 and INOS was examined using immunofluorescence staining and western blot analysis. In addition, reverse transcription‑quantitative PCR was employed to examine the expression of TNF‑α, IL‑6 and IL‑1β in macrophages. The binding between Wnt7B and FZD4 was estimated using co‑immunoprecipitation. In addition, FZD4 was silenced to perform the rescue experiments to elucidate the regulatory mechanism between Wnt7B and FZD4. The results demonstrated a decreased expression of Wnt7B in periodontitis‑affected gingival tissue and in LPS‑exposed PDLSCs. Wnt7B overexpression promoted the osteogenic differentiation of LPS‑exposed PDLSCs and suppressed the M1 polarization of macrophages. Additionally, Wnt7B bound to FZD4 and upregulated FZD4 expression. FZD4 silencing reversed the effects of Wnt7B overexpression on the osteogenic differentiation in LPS‑exposed PDLSCs and the M1 polarization of macrophages. In summary, Wnt7B plays an anti‑periodontitis role by binding FZD4 to strengthen the osteogenic differentiation of LPS‑stimulated PDLSCs and suppress the M1 polarization of macrophages.