Polarization of human gingival fibroblasts by Th1‐, Th2‐, Th17‐, and Treg‐derived cytokines

The purpose of this study was to evaluate whether gingival fibroblasts (GFs) can be differently activated and polarized into distinct functional subtypes by T-helper (Th) cytokines.Gingival fibroblasts were stimulated with interferon (IFN)-γ, interleukin (IL)-4, IL-17, and transforming growth factor (TGF)-β, representative cytokines of Th1, Th2, Th17, and regulatory T cells, respectively, and the gene expression profiles were analyzed by microarray. Differentially expressed genes (DEGs) in GFs stimulated by 4 cytokines were screened, and a gene ontology (GO) analysis of the DEGs was conducted. To confirm the reliability of the microarray results, the DEGs that showed the largest differences compared with non-stimulated GFs were further analyzed by RT-PCR. To evaluate the effect of polarization on GFs responses to lipopolysaccharide (LPS), GFs stimulated by 4 cytokines were further stimulated with Escherichia coli LPS and mRNA levels of several genes were analyzed using RT-PCR.Differentially expressed genes by 4 Th cytokines were enriched in different GO terms, and the patterns of gene expression on GFs were shown functionally different. GFs stimulated with IFN-γ (GF(IFN-γ)) up-regulated the expression of chemokines (chemokine (C-X-C motif) ligand (CXCL)9, -10, -11, chemokine (C-C motif) ligand (CCL)8), molecules involved in antigen presentation, complement component 3 (C3), and other immune response-related molecules, whereas they down-regulated the expression of several types of collagen, extracellular matrix (ECM) components, and DNA replication and nuclear protein-related molecules. By contrast, GF(IL-4) up-regulated the expression of ECM components, cell adhesion molecules, and tissue development-related molecules and down-regulated the expression of chemokines (CXCL10 and CXCL8) and adaptive immune response-related molecules. GF(IL-17) up-regulated the expression of chemokines and other molecules for neutrophil infiltration and activation, the pro-inflammatory cytokine IL-6, and C3. GF(TGF-β) up-regulated the expression of cell growth-related molecules, ECM components, several types of collagen, and cell adhesion molecules and down-regulated the expression of molecules related to complement activation and bacterial recognition. GFs stimulated by 4 cytokines responded differently to LPS.These results show that Th cytokines can polarize GFs into cells with functionally distinct features: immune-activating but tissue-destructive GF(IFN-γ), tissue-reparative, and immune-inhibiting GF(IL-4), highly pro-inflammatory GF(IL-17), and potent tissue-reparative GF(TGF-β).