RESUMO
One of the characteristics of the cerebral aging process is the presence of chronic inflammation through glial cells, which is particularly significant in neurodegeneration. On the other hand, it has been demonstrated that the aryl hydrocarbon receptor (AHR) participates in the inflammatory response. Currently, evidence in animal models shows that the hallmarks of aging are associated with changes in the AHR levels. However, there is no information concerning the behavior and participation of AHR in the human aging brain or in Alzheimer's disease (AD). We evaluated the expression of AHR in human hippocampal post-mortem tissue and its association with reactive astrocytes by immunohistochemistry. Besides this, we analyzed through ELISA the AHR levels in blood serum from young and elder participants, and from AD patients. The levels of AHR and glial fibrillar acid protein were higher in elder than in young post-mortem brain samples. AHR was localized mainly in the cytosol of astrocytes and displayed a pattern that resembles extracellular vesicles; this latter feature was more conspicuous in AD subjects. We found higher serum levels of AHR in AD patients than in the other participants. These results suggest that AHR participates in the aging process, and probably in the development of neurodegenerative diseases like AD.
Assuntos
Doença de Alzheimer/metabolismo , Astrócitos/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/análise , Fatores de Transcrição Hélice-Alça-Hélice Básicos/sangue , Hipocampo/metabolismo , Receptores de Hidrocarboneto Arílico/análise , Receptores de Hidrocarboneto Arílico/sangue , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/fisiologia , Animais , Ensaio de Imunoadsorção Enzimática , Vesículas Extracelulares/metabolismo , Feminino , Proteína Glial Fibrilar Ácida/análise , Humanos , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Adulto JovemRESUMO
Vitamin D has been known to have important regulatory functions in inflammation and immune response and shows inhibitory effects on experimental periodontitis in animal models. However, the potential mechanism has yet to be clarified. Recent studies have highlighted Aryl hydrocarbon receptor (AhR) and its downstream signaling as a crucial regulator of immune homeostasis and inflammatory regulation. OBJECTIVE: This study aimed to clarify the effect of 1,25-dihydroxyvitamin D3 (VD3) on experimental periodontitis and AhR/nuclear factor-κB (NF-κB)/NLR pyrin domain-containing 3 (NLRP3) inflammasome pathway in the gingival epithelium in a murine model. METHODOLOGY: We induced periodontitis in male C57BL/6 wild-type mice by oral inoculation of Porphyromonas gingivalis (P. gingivalis), and subsequently gave intraperitoneal VD3 injection to the mice every other day for 8 weeks. Afterwards, we examined the alveolar bone using scanning electron microscopy (SEM) and detected the gingival epithelial protein using western blot analysis and immunohistochemical staining. RESULTS: SEM images demonstrated that alveolar bone loss was reduced in the periodontitis mouse model after VD3 supplementation. Western blot analyses and immunohistochemical staining of the gingival epithelium showed that the expression of vitamin D receptor, AhR and its downstream cytochrome P450 1A1 were enhanced upon VD3 application. Additionally, VD3 decreased NF-κB p65 phosphorylation, and NLRP3, apoptosis-associated speck-like protein, caspase-1, interleukin-1ß (IL-1ß) and IL-6 protein expression. CONCLUSIONS: These results implicate the alleviation of periodontitis and the alteration of AhR/NF-κB/NLRP3 inflammasome pathway by VD3 in the mouse model. The attenuation of this periodontal disease may correlate with the regulation of AhR/NF-κB/NLRP3 inflammasome pathway by VD3.
Assuntos
Conservadores da Densidade Óssea/farmacologia , Calcitriol/farmacologia , NF-kappa B/efeitos dos fármacos , Proteína 3 que Contém Domínio de Pirina da Família NLR/efeitos dos fármacos , Periodontite/tratamento farmacológico , Periodontite/metabolismo , Receptores de Hidrocarboneto Arílico/efeitos dos fármacos , Perda do Osso Alveolar , Animais , Western Blotting , Conservadores da Densidade Óssea/análise , Calcitriol/análise , Caspase 1/análise , Gengiva/efeitos dos fármacos , Gengiva/metabolismo , Gengiva/patologia , Imuno-Histoquímica , Interleucina-1beta/análise , Interleucina-6/análise , Masculino , Camundongos Endogâmicos C57BL , NF-kappa B/análise , Proteína 3 que Contém Domínio de Pirina da Família NLR/análise , Periodontite/patologia , Porphyromonas gingivalis , Receptores de Hidrocarboneto Arílico/análise , Valores de Referência , Reprodutibilidade dos Testes , Resultado do TratamentoRESUMO
Abstract Vitamin D has been known to have important regulatory functions in inflammation and immune response and shows inhibitory effects on experimental periodontitis in animal models. However, the potential mechanism has yet to be clarified. Recent studies have highlighted Aryl hydrocarbon receptor (AhR) and its downstream signaling as a crucial regulator of immune homeostasis and inflammatory regulation. Objective: This study aimed to clarify the effect of 1,25-dihydroxyvitamin D3 (VD3) on experimental periodontitis and AhR/nuclear factor-κB (NF-κB)/NLR pyrin domain-containing 3 (NLRP3) inflammasome pathway in the gingival epithelium in a murine model. Methodology: We induced periodontitis in male C57BL/6 wild-type mice by oral inoculation of Porphyromonas gingivalis (P. gingivalis), and subsequently gave intraperitoneal VD3 injection to the mice every other day for 8 weeks. Afterwards, we examined the alveolar bone using scanning electron microscopy (SEM) and detected the gingival epithelial protein using western blot analysis and immunohistochemical staining. Results: SEM images demonstrated that alveolar bone loss was reduced in the periodontitis mouse model after VD3 supplementation. Western blot analyses and immunohistochemical staining of the gingival epithelium showed that the expression of vitamin D receptor, AhR and its downstream cytochrome P450 1A1 were enhanced upon VD3 application. Additionally, VD3 decreased NF-κB p65 phosphorylation, and NLRP3, apoptosis-associated speck-like protein, caspase-1, interleukin-1β (IL-1β) and IL-6 protein expression. Conclusions: These results implicate the alleviation of periodontitis and the alteration of AhR/NF-κB/NLRP3 inflammasome pathway by VD3 in the mouse model. The attenuation of this periodontal disease may correlate with the regulation of AhR/NF-κB/NLRP3 inflammasome pathway by VD3.
Assuntos
Animais , Masculino , Periodontite/metabolismo , Periodontite/tratamento farmacológico , Calcitriol/farmacologia , NF-kappa B/efeitos dos fármacos , Conservadores da Densidade Óssea/farmacologia , Proteína 3 que Contém Domínio de Pirina da Família NLR/efeitos dos fármacos , Periodontite/patologia , Valores de Referência , Calcitriol/análise , Imuno-Histoquímica , Western Blotting , Reprodutibilidade dos Testes , Perda do Osso Alveolar , NF-kappa B/análise , Interleucina-6/análise , Resultado do Tratamento , Receptores de Hidrocarboneto Arílico/análise , Receptores de Hidrocarboneto Arílico/efeitos dos fármacos , Porphyromonas gingivalis , Caspase 1/análise , Conservadores da Densidade Óssea/análise , Interleucina-1beta/análise , Proteína 3 que Contém Domínio de Pirina da Família NLR/análise , Gengiva/efeitos dos fármacos , Gengiva/metabolismo , Gengiva/patologia , Camundongos Endogâmicos C57BLRESUMO
BACKGROUND AND OBJECTIVE: Two new T-helper (Th) phenotypes have been recently described and named Th9 and Th22 lymphocytes; however, their role in the pathogenesis of periodontitis remains unclear. This study was aimed to assess whether Th9 and Th22 lymphocytes, through interleukin (IL)-9 and IL-22 production, respectively, are associated with the severity of periodontitis and bone resorption. MATERIAL AND METHODS: Gingival crevicular fluid samples and biopsies were obtained from patients with moderate-to-advanced chronic periodontitis and gingivitis, and healthy controls. The levels for the Th9 and Th22-associated cytokines and master-switch transcription factors Spi-B and aryl hydrocarbon receptor (AhR) were quantified by enzyme-linked immunosorbent assay, real-time reverse-transcription quantitative polymerase chain reaction and flow cytometry. In addition, the osteoclast activity in response to tissue homogenates from periodontitis and healthy samples was analyzed quantifying the number of TRAP-positive cells and areas of bone resorption pits produced, in the presence or absence of recombinant human IL-22 and anti-IL-22 neutralization antibody. RESULTS: Higher levels of IL-22 and AhR were detected in patients with periodontitis compared with gingivitis and healthy individuals. In addition, higher levels of IL-9 and Spi-B were detected in gingivitis patients compared with periodontitis and healthy individuals. In patients with periodontitis, a significant positive correlation was detected between secreted levels of IL-22 and clinical attachment level of the sampled periodontal pockets. When osteoclasts were exposed to tissue homogenates obtained from patients with periodontitis, higher levels of resorptive activity were observed as compared with the same cells exposed to tissue homogenates obtained from healthy individuals, and this increment was dependent on the presence and neutralization of IL-22. CONCLUSION: Increased levels of IL-22 produced by Th22 lymphocytes are associated with the pathogenesis of periodontitis, in particular, with osteoclast resorptive activity and severity of disease.
Assuntos
Periodontite Crônica/imunologia , Citocinas/metabolismo , Líquido do Sulco Gengival/química , Interleucinas/metabolismo , Osteoclastos/imunologia , Osteoclastos/metabolismo , Receptores de Hidrocarboneto Arílico/metabolismo , Adulto , Periodontite Crônica/patologia , Citocinas/análise , Citocinas/genética , Proteínas de Ligação a DNA/análise , Proteínas de Ligação a DNA/metabolismo , Feminino , Expressão Gênica , Gengivite/imunologia , Gengivite/patologia , Humanos , Interleucina-9/análise , Interleucina-9/metabolismo , Interleucinas/análise , Masculino , Perda da Inserção Periodontal , Bolsa Periodontal/imunologia , RNA/isolamento & purificação , RNA Ribossômico 18S/análise , Receptores de Hidrocarboneto Arílico/análise , Fatores de Transcrição/análise , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Interleucina 22RESUMO
Aryl Hydrocarbon Receptor (AhR) ligands also known as dioxin-like compounds, constitute a substantial part of the total toxicity from many pollution sources, including pulp mill effluents. The aim of this article was to evaluate dioxin-like activity in different kraft mill effluents by a combination of yeast bioassays and gas chromatography-mass spectrometry (GC-MS) chemical analysis. The study includes kraft mill effluents from three sources of raw material: Pinus radiata, Eucalyptus globulus and a combination of both (50% each). The Recombinant Yeast Assay (RYA) showed an effective concentration of AhR ligands more than 30-fold higher in Eucalyptus globulus than in Pinus radiata effluents. Our results suggest that specific ligands, rather than the total amount of extractive material, determined the observed activity. Analysis of extract composition by GC-MS indicated that moderately hydrophobic aromatic compounds were likely responsible for the observed dioxin-like activity. In particular, benzaldehyde derivatives appeared as candidates for eliciting the observed dioxin-like activity in pulp mill effluents, giving their structural properties and their high concentration in AhR ligand-rich samples.