RESUMO
Acute exposure to bacterial lipopolysaccharide (LPS) is a potent inducer of immune response as well as hypophagia. Nevertheless, desensitization of responses to LPS occurs during long-term exposure to endotoxin. We induced endotoxin tolerance, injecting repeated (6LPS) LPS doses compared with single (1LPS) treatment. 1LPS, but not 6LPS group, showed decreased food intake and body weight, which was associated with an increased plasma leptin and higher mRNA expression of OB-Rb, MC4R, and SOCS3 in the hypothalamus. Hypophagia induced by 1LPS was associated with lower levels of 2-arachidonoylglycerol (2-AG), increased number of p-STAT3 neurons, and decreased AMP-activated protein kinase (AMPK) activity. Desensitization of hypophagia in the 6LPS group was related to high 2-AG, with no changes in p-STAT3 or increased p-AMPK. Leptin decreased food intake, body weight, 2-AG levels, and AMPK activity and enhanced p-STAT3 in control rats. However, leptin had no effects on 2-AG, p-STAT3, or p-AMPK in the 1LPS and 6LPS groups. Rats treated with HFD to induce leptin resistance showed neither hypophagia nor changes in p-STAT3 after 1LPS, suggesting that leptin and LPS recruit a common signaling pathway in the hypothalamus to modulate food intake reduction. Desensitization of hypophagia in response to repeated exposure to endotoxin is related to an inability of leptin to inhibit AMPK phosphorylation and 2-AG production and activate STAT3. SOCS3 is unlikely to underlie this resistance to leptin signaling in the endotoxin tolerance. The present model of prolonged inflammatory challenge may contribute to further investigations on mechanisms of leptin resistance.
Assuntos
Ingestão de Alimentos/fisiologia , Inflamação/fisiopatologia , Leptina/fisiologia , Animais , Ácidos Araquidônicos/fisiologia , Peso Corporal/efeitos dos fármacos , Peso Corporal/fisiologia , Proteínas Quinases Dependentes de AMP Cíclico/fisiologia , Dieta , Gorduras na Dieta/farmacologia , Ingestão de Alimentos/efeitos dos fármacos , Endocanabinoides , Endotoxinas/farmacologia , Cromatografia Gasosa-Espectrometria de Massas , Glicerídeos/fisiologia , Imuno-Histoquímica , Inflamação/induzido quimicamente , Interleucina-10/biossíntese , Interleucina-10/genética , Leptina/sangue , Lipopolissacarídeos/farmacologia , Masculino , Fosforilação , Ratos , Ratos Wistar , Receptor Tipo 4 de Melanocortina/biossíntese , Receptor Tipo 4 de Melanocortina/genética , Receptor Tipo 4 de Melanocortina/fisiologia , Receptores de Interleucina-10/biossíntese , Receptores de Interleucina-10/genética , Receptores para Leptina/biossíntese , Receptores para Leptina/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fator de Transcrição STAT3/biossíntese , Fator de Transcrição STAT3/genética , Transdução de Sinais/fisiologia , Proteína 3 Supressora da Sinalização de Citocinas , Proteínas Supressoras da Sinalização de Citocina/biossíntese , Proteínas Supressoras da Sinalização de Citocina/genéticaRESUMO
OBJECTIVE: Central giant cell lesions (CGCL) and peripheral giant cell lesions (PGCL) occur in the jaws and contain osteoclast-like giant cells and mononuclear cells positive for the macrophage marker CD68. The participation of immune-inflammatory mechanisms has been proposed in the lesions development. As IL-10 is one of the most important anti-inflammatory cytokines and it is also an inhibitory cytokine to macrophage function and bone resorption, the purpose of the present study was to investigate its expression together with its receptor (IL-10Rα) in CGCL and PGCL. STUDY DESIGN: Six fragments of CGCL and seven fragments of PGCL were obtained by surgical excision. Frozen specimens were cut and subjected to immunofluorescence staining using fluorescent-labeled anti-CD68, anti-IL-10, and anti-IL-10Rα monoclonal antibodies. Microscopic analyses were performed and the percentage of positive mononuclear and giant cells for each parameter was obtained. RESULTS: Our results revealed that all giant cells from CGCL and PGCL were CD68+ and IL-10Rα+ and that the majority was also positive for IL-10. More than 50% of the mononuclear cells from both lesions expressed IL-10Rα and the majority of these cells were CD68+ and IL-10+. CONCLUSION: Considering that IL-10 has inhibitory effects on the pathologic processes related to the development of the oral giant cell lesions, the high frequencies of cells producing this cytokine seems contradictory to these lesions growth. Investigation about the production of inflammatory cytokines as well as the IL-10 signaling pathways in oral giant cell lesions is required to elucidate the immunopathology of CGCL and PGCL.
Assuntos
Granuloma de Células Gigantes/metabolismo , Interleucina-10/biossíntese , Doenças da Boca/metabolismo , Receptores de Interleucina-10/biossíntese , Adulto , Criança , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
Antitumor immune responses are associated with proinflammatory cytokines, whereas tumor-developing animals generally have increased the production of immunosuppressive cytokines. Here, we show that splenocytes from C57Bl/6 mice resistant to low doses of B16F10-Nex2 melanoma cells produced twofold or higher interferon-γ (IFN-γ)/interleukin-10 (IL-10) ratios, whereas cells from tumor-bearing animals produced predominantly IL-10. IL-10-knockout (IL-10KO) mice were significantly more resistant to B16F10-Nex2 development, producing increased amounts of IL-12 and IFN-γ. To neutralize IL-10 in vivo, aiming at cancer therapy, recombinant eukaryotic plasmid expressing the soluble extracellular region of the murine IL-10 receptor α-chain was constructed (pcDNA3-sIL-10R). Plasmid-treated melanoma-challenged animals showed extended survival time, the protective response was IFN-γ dependent and enhanced by co-immunization with a plasmid expressing IL-12. Dendritic cells (DCs) from IL-10KO mice, primed with B16F10-Nex2 antigens (TAg), secreted increased amounts of T-helper 1-type cytokines and increased the expression of surface activation markers. Vaccination of C57Bl/6 mice with TAg-activated IL-10KO DCs, as well as with TAg-primed DCs from C57Bl/6 mice transfected with pcDNA3-sIL10R plasmid, significantly increased animal survival. In conclusion, an IFN-γ-dependent protective response was induced against B16F10-Nex2 cells by neutralization of IL-10 with pcDNA3-sIL10R plasmid. This effect was enhanced by association with IL-12 gene therapy (80% protection), and could be mediated by TAg-primed DCs.