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This article supports the participation of humoral immune alterations in chronic periodontal disease resulting in postsynaptic functional deregulation. Overproduction of proinflammatory mediators (PGE(2) and CD40 expression) is induced as a consequence of antibody-beta(1)-AR interaction. The PGE(2)-CD40-IgG axis may play a part in the pathophysiological mechanisms underlying the inflammatory process in chronic periodontal disease.

Activation of mAChR subtypes stimulated NOS activity by increasing the production of NO through e-nos and n-nos gene expression and NOS activity. The mechanism appears to occur secondarily to stimulation of CaM and PKC enzymatic activity.

Background: Evidences have shown that β₁ and β₂ adrenoceptors co-exist in human fibroblasts, but it is not yet clear the functional expression of β₃ adrenoceptor in these cells. The aim of this study was to investigate the expression and biological effect of β₃ adrenoceptor activation in human skin fibroblast and the different signaling pathways involved in its effect. Methods: For this purpose in vitro cultures of human skin fibroblast were established from human foreskin and grown in Dulbecco’s modified Eagle’s medium. The effect of ZD 7114 (β₃ agonist) on cell DNA synthesis, radioligand binding assay, cyclic GMP and cyclic AMP accumulation and nitric oxide synthase (NOS) activity were evaluated. Results: ³H-CGP binding to human fibroblast membranes was a saturable process to a single class of binding site. The equilibrium parameters were: Kd 20±3 pM and Bmax 222±19 fmol/mg protein. Ki values showed that these cells express a high number of β₃adrenoceptor subtypes. ZD 7114 stimulation of β₃ adrenoceptor exerts a concentration-dependent inhibition of DNA synthesis and cAMP accumulation with parallel increase in NOS activity that led to cGMP accumulation. All these effects were blocked by the β₃ adrenoceptor antagonist (SR 59230A). The effect of ZD 7114 on DNA synthesis significantly correlated with its action either on cAMP or NOS-cGMP signaling system. Inhibitors of NOS activity and NO-sensitive guanylate cyclase prevented the inhibitory effect of ZD 7114 on DNA synthesis. In addition, the β₃ adrenoceptor-dependent increase in cGMP and activation of NOS were blocked by the inhibition of phospholipase C (PLC), calcium/calmodulin (CaM), endothelial NOS activity and cGMP accumulation. Conclusions: β₃ adrenoceptor activation exerts inhibitory effect on human fibroblast DNA synthesis as a result of the activation of NO-cGMP pathway and the inhibition of adenylate cyclase activity. The mechanism appears to occurs secondarily to stimulation of PLC and CaM. This in turn triggers cascade reaction leading to increase production of NO-cGMP with decrease in cAMP accumulation.

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1 The aim of the present work was to examine the role of muscarinic acetylcholine receptors (mAChR) on DNA synthesis and CD40 expression in human fibroblast cells. Neonatal human skin fibroblast cultures were stimulated with carbachol in presence or absence of specific antagonists and the following parameters were measured: identification of mAChR subtypes, DNA synthesis, inositol phosphates (InsP) production and CD40 expression. 2 Human fibroblasts express mAChR with Kd 0.47 +/- 0.11 nm and Bmax 236 +/- 22 fmol mg protein(-1). Carbachol stimulates DNA synthesis, InsP and the expression of CD40. All these effects were inhibited by atropine, mustard hydrochloride (4-DAMP) and pirenzepine but not by AF-DX 116 and tropicamide, indicating that M3 and M1 mAChR are implicated in carbachol action. The relative Ki of the antagonists obtained by competition binding assay was in parallel to the relative potency for blocking both carbachol-stimulated InsP accumulation and DNA synthesis. 3 The intracellular pathway leading to carbachol-induced biological effects involved phospholipase C and calcium/calmodulin, as U-73122 and trifluoroperazine blocked carbachol effects, respectively. Calphostin C, a protein kinase C inhibitor, had no effect, indicating that this enzyme does not participate in the system. 4 These results may contribute to a better understanding of the modulatory role of the parasympathetic muscarinic system on normal human fibroblast function.

ObjectivesTo demonstrate the presence of circulating autoantibodies (Abs) from patients with chronic periodontitis (CP) that interacted with human gingival fibroblast membranes activating β1 adrenoceptors (β1-AR).MethodsSera and purified IgG from 25 patients with CP and 20 age-matched healthy subjects were studied by flow cytometry, ELISA and DNA synthesis. Human gingival fibroblast membranes and/or synthetic peptides with amino acid sequences identical to human β1-AR were used as antigens.ResultsBy flow cytometry and ELISA procedures, we proved that the serum-purified IgG fraction from patients with CP reacted with the fibroblast surface and to the β1 synthetic peptide. The corresponding affinity-purified anti-β1 peptide Abs displayed agonist-like activity associated with specific receptor activation, inhibiting the DNA synthesis of human gingival fibroblasts.ConclusionsThis study demonstrates that β1-AR autoantibodies are elevated in patients with CP. These autoantibodies were targeted to the fibroblasts, and specifically to the β1-AR, and has receptor-like activity inhibiting DNA synthesis.

CD40, a member of the tumour necrosis factor-alpha receptor family, is constitutively expressed by cells of haematopoietic and non-haematopoietic origin, including fibroblasts. Signalling through this receptor molecule regulates inflammatory mediator secretion by many cell types. The work has been performed in healthy subjects and the authors studied, by cellular culture, flow cytometric analysis and ELISA assay, the expression of CD40 and PGE2 (prostaglandin E2) generation on gingival fibroblasts stimulated by beta-AR (beta-adrenoceptor) agonists. Herein, the authors demonstrate that beta-AR subtype activation via their own specific agonists markedly increased CD40 expression on human gingival fibroblasts. This effect was prevented by beta-AR subtype-specific antagonists. In addition, gingival fibroblast beta-AR stimulation resulted in an increase in PGE2 generation. The inhibition of PLA2 (phospholipase A2) and COX-1 (cyclo-oxygenase-1) but not COX-2 impaired beta-AR increase of PGE2, an effect that was restored by the addition of low concentrations of PGE2, suggesting that PGE2 generation is implicated in the mechanism underlying beta-AR-agonist-mediated CD40 overexpression. Our work has revealed an endogenous beta-AR mediator network involving gingival fibroblasts.