ABSTRACT
Abstract Local administration of toll-like receptor 9 (TLR9), agonist cytidine-phosphate-guanosine oligodeoxynucleotide (CpG ODNs), and CD40 ligand (CD40L) can decrease ligature-induced periodontal inflammation and bone loss in wild type (WT) mouse. Objective: This study aimed to explore whether such effect is dependent on TLR9 signaling. Material and Methods: Purified spleen B cells isolated from WT C57BL/6J mice and TLR9 knockout (KO) mice were cultured for 48 hours under the following conditions: CD40L, CpG+CD40L, CpG at low, medium and high doses. We determined B cell numbers using a hemocytometer at 24 h and 48 h. Percentages of CD1dhiCD5+ B cells were detected by flow cytometry. Interleukin-10 (IL-10) mRNA expression and protein secretion were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and by ELISA, respectively. The silk ligature was tied around the maxillary second molars for 14 days, during which the CpG+CD40L mixture or PBS was injected into palatal gingiva on days 3, 6, and 9. Results: For both WT and TLR9 KO mice, CpG significantly induced B cell proliferation, increased IL-10 mRNA expression and protein secretion of IL-10 but reduced CD1dhiCD5+ B cells population; local injection of CpG+CD40L mixture significantly decreased alveolar bone loss and the number of TRAP-positive cells adjacent to the alveolar bone surface, and significantly increased the gingival mRNA expression of IL-10 and decreased RANKL and IFN-γ mRNA expression. Conclusions: These results indicated that CpG plus CD40L decreased periodontal inflammation and alveolar bone loss in a TLR9-independent manner in ligature-induced experimental periodontitis.
Subject(s)
Animals , Oligodeoxyribonucleotides/pharmacology , Periodontitis/drug therapy , Alveolar Bone Loss/drug therapy , CD40 Ligand/pharmacology , Cytidine/pharmacology , Toll-Like Receptor 9/drug effects , Guanine Nucleotides/pharmacology , Reference Values , Time Factors , Enzyme-Linked Immunosorbent Assay , B-Lymphocytes/drug effects , Cells, Cultured , Adjuvants, Immunologic/pharmacology , Reproducibility of Results , Interleukin-10/analysis , Disease Models, Animal , Toll-Like Receptor 9/analysis , Real-Time Polymerase Chain Reaction , Flow Cytometry , Gingiva/drug effects , Gingiva/pathology , Mice, Inbred C57BLABSTRACT
Cytokine and chemokine receptors play a key role in inflammation caused by rheumatoid arthritis (RA). Two isoforms of human CC chemokine receptor R2 (CCR2), the receptor of monocyte chemoattractant protein 1 (MCP-1), have been identified but their relative expression in fibroblast-like synoviocytes (FLS) and their contribution to inflammatory responses mediated by MCP-1 or inflammatory cytokines in patients with RA remain uncertain. We examined the pattern of expression of two CCR2 isoforms upon stimulation by proinflammatory cytokines and CD40 ligation. FLS were prepared from the synovial tissues of RA patients and cultured in the presence of MCP-1, soluble CD40 ligand (sCD40L), TGF-beta, IL-1beta, IL-18, IL-15, and LPS. CCR2A and CCR2B expression was examined by immunohistochemistry, RT-PCR and western blot analysis. IL-15, TNF-alpha and MCP-1 production was determined by ELISA. Immunohistochemistry showed that CCR2A is highly expressed in RA synovium compared with OA synovium. Transcripts of both CCR2A and CCR2B were detected in FLS. Exogenous MCP-1, CD40L, TGF-beta, and IL-15 significantly increased the expression of CCR2A but not CCR2B. Exposure of FLS to sCD40L caused strong upregulation of CCR2A but not of CCR2B protein expression. MCP-1 increased the proliferation of FLS and the production of IL-15, TNF-alpha, and IL-18. Because CCR2A is the main target of regulation by cytokines and CD40 ligation, the relatively higher expression of CCR2A on the cell surface suggests that this isoform of MCP-1 receptor functions as the principal mediator of inflammatory signals in RA FLS.