RESUMO
BACKGROUND: Xylitol is a well-known anticaries agent and has been used for the prevention and treatment of dental caries. In this study, the anti-inflammatory effects of xylitol are evaluated for possible use in the prevention and treatment of periodontal infections. METHODS: Cytokine expression was stimulated in THP-1 (human monocyte cell line)-derived macrophages by live Porphyromonas gingivalis, and enzyme-linked immunosorbent assay and a commercial multiplex assay kit were used to determine the effects of xylitol on live P. gingivalis-induced production of cytokine. The effects of xylitol on phagocytosis and the production of nitric oxide were determined using phagocytosis assay, viable cell count, and Griess reagent. The effects of xylitol on P. gingivalis adhesion were determined by immunostaining, and costimulatory molecule expression was examined by flow cytometry. RESULTS: Live P. gingivalis infection increased the production of representative proinflammatory cytokines, such as tumor necrosis factor-α and interleukin (IL)-1ß, in a multiplicity of infection- and time-dependent manner. Live P. gingivalis also enhanced the release of cytokines and chemokines, such as IL-12 p40, eotaxin, interferon γ-induced protein 10, monocyte chemotactic protein-1, and macrophage inflammatory protein-1. The pretreatment of xylitol significantly inhibited the P. gingivalis-induced cytokines production and nitric oxide production. In addition, xylitol inhibited the attachment of live P. gingivalis on THP-1-derived macrophages. Furthermore, xylitol exerted antiphagocytic activity against both Escherichia coli and P. gingivalis. CONCLUSION: These findings suggest that xylitol acts as an anti-inflammatory agent in THP-1-derived macrophages infected with live P. gingivalis, which supports its use in periodontitis.
Assuntos
Anti-Inflamatórios/farmacologia , Macrófagos/efeitos dos fármacos , Porphyromonas gingivalis/efeitos dos fármacos , Xilitol/farmacologia , Aderência Bacteriana/efeitos dos fármacos , Contagem de Células , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Quimiocina CCL2/efeitos dos fármacos , Quimiocina CXCL10/efeitos dos fármacos , Quimiocinas CC/efeitos dos fármacos , Citocinas/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Humanos , Epitopos Imunodominantes/efeitos dos fármacos , Fatores Imunológicos/farmacologia , Interleucina-12/análise , Interleucina-1beta/efeitos dos fármacos , Proteínas Inflamatórias de Macrófagos/efeitos dos fármacos , Macrófagos/microbiologia , Monócitos/imunologia , Óxido Nítrico/análise , Fragmentos de Peptídeos/efeitos dos fármacos , Fagocitose/efeitos dos fármacos , Porphyromonas gingivalis/imunologia , Fator de Necrose Tumoral alfa/efeitos dos fármacosRESUMO
APCs operate frequently under oxidative stress induced by aging, tissue damage, pathogens, or inflammatory responses. Phagocytic cells produce peroxides and free-radical species that facilitate pathogen clearance and can in the case of APCs, also lead to oxidative modifications of antigenic proteins and peptides. Little information is available presently about the consequences of such modifications on the immune response. To model oxidative modification of an immunodominant antigenic peptide, we oxidized the methionine residue of the human CMV pp65(495-503) (NLVPMVATV) peptide. Such modifications of an antigenic peptide can affect MHC binding or TCR recognition. Using binding and dissociation assays, we demonstrate that oxidative modification of the CMVpp65(495-503) peptide leads to a decreased binding of the pMHC complex to the TCR, whereas binding of the peptide to the MHC class I molecule is not impaired. Additionally, we show that CD8(+) T cells have a decreased proliferation and IFN-gamma production when stimulated with oxidized CMVpp65(495-503) peptide. Spectratyping the antigen-binding site of the TCR of responding T cells demonstrates that the CMVpp65(495-503) and the CMVoxpp65(495-503) peptides preferentially stimulate BV8 T cells. Sequencing of this dominant BV family reveals a highly conserved CDR3 amino acid motif, independent of the mode of stimulation, demonstrating the recruitment of the same T cell clonotypes. Our results suggest that oxidative modification of antigenic peptides may affect T cell responses severely by binding T cell clones with different affinity. This may lead to an altered immune response against infectious agents as well as against tumor or autoantigens under oxidative stress conditions.
Assuntos
Células Apresentadoras de Antígenos/imunologia , Antígenos Virais/imunologia , Linfócitos T CD8-Positivos/imunologia , Epitopos Imunodominantes/imunologia , Estresse Oxidativo/imunologia , Fosfoproteínas/imunologia , Proteínas da Matriz Viral/imunologia , Adulto , Motivos de Aminoácidos , Antígenos Virais/química , Antígenos Virais/efeitos dos fármacos , Células Cultivadas/imunologia , Infecções por Citomegalovirus/imunologia , Feminino , Antígenos HLA-A/imunologia , Antígeno HLA-A2 , Humanos , Peróxido de Hidrogênio/farmacologia , Epitopos Imunodominantes/efeitos dos fármacos , Interferon gama/biossíntese , Ativação Linfocitária , Masculino , Metionina/química , Oxirredução , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/efeitos dos fármacos , Fragmentos de Peptídeos/imunologia , Fosfoproteínas/química , Fosfoproteínas/efeitos dos fármacos , Receptores de Antígenos de Linfócitos T alfa-beta/imunologia , Proteínas da Matriz Viral/química , Proteínas da Matriz Viral/efeitos dos fármacosRESUMO
A line of tumor-infiltrating lymphocytes (660TIL) specifically lysed the autologous HLA-A2+ melanoma (660MEL) and also most A2+ melanoma cell lines. We immunoprecipitated A2 from a large number (>10(12)) of 660MEL cells, extracted naturally processed peptides, fractionated them by HPLC, screened the fractions for recognition by 660TIL, and found a single predominant and a minor peak of activity. Although too little was recovered of the major 660MEL peptide to establish its sequence, HPLC fingerprinting showed that it did not correspond to any of the known A2-associated melanoma peptides recognized by T cells, including peptides from tyrosinase, MART-1/Melan-A, gp100 and MAGE-3. The major 660MEL antigenic peptide appears to be derived from MART-1/Melan-A but is neither AAGIGILTV nor ILTVILGVL nor any other MART-1/Melan-A peptide containing the A2 consensus motif. The multiplicity of melanoma peptides recognized by CD8+ T cells, most of which are non-mutated (including most likely the present 660MEL peptide), suggests the existence of unknown mechanisms, perhaps similar to those operating in autoimmune disorders, whereby T cells that recognize normal 'self' sequences become activated.
Assuntos
Autoantígenos/imunologia , Citotoxicidade Imunológica , Melanoma/imunologia , Proteínas de Neoplasias/imunologia , Peptídeos/imunologia , Linfócitos T Citotóxicos/imunologia , Apresentação de Antígeno , Antígenos de Neoplasias , Autoimunidade/imunologia , Autoimunidade/fisiologia , Biomarcadores Tumorais/imunologia , Sequência Consenso , Testes Imunológicos de Citotoxicidade , Humanos , Epitopos Imunodominantes/efeitos dos fármacos , Epitopos Imunodominantes/imunologia , Linfócitos do Interstício Tumoral/imunologia , Linfócitos do Interstício Tumoral/metabolismo , Antígeno MART-1 , Melanoma/terapia , Proteínas de Neoplasias/metabolismo , Proteínas de Neoplasias/fisiologia , Peptídeos/metabolismo , Peptídeos/fisiologia , Linfócitos T Citotóxicos/metabolismo , Linfócitos T Citotóxicos/fisiologia , Células Tumorais CultivadasRESUMO
Immunodominance (ID) of T cell epitopes is a well-documented phenomenon that might have profound significance in the evolution of T cell responses to pathogens, tumors, autoantigens and vaccines. With the intention of developing vaccines composed of several cytotoxic T cell (CTL) epitopes, we injected mice with peptide mixtures containing two to five CTL epitopes and observed clear patterns of ID. In a first case, ID strictly correlated with the competitor activity of the individual peptides for H-2Kd, whereas in a second case, the absence of correlation between ID and competitor activity, binding affinity, half-life of the peptides in serum, induction of proliferation in vitro and the individual immunogenicity of the peptides, suggested to us that ID of co-injected CTL epitopes can be determined both at the peptide level (binding affinity to H-2Kd) and at the T cell level. This hypothesis is supported by our finding that interleukin-12 strongly modulates ID when it is not correlated with MHC binding.