RESUMO
The ovine choroid plexus (ChP) expresses the long isoform of the leptin receptor, which makes this structure a potential target for leptin action. In sheep, leptin concentration in plasma is higher during long days (LD) than short days (SD). This study evaluates the influence a of photoperiod on leptin impact on the gene expression of Toll-like receptor 4 (TLR4), proinflammatory cytokines (IL1B, IL6), their receptors (IL1R1, IL1R2, ILRN, IL6R, IL6ST) and inflammasome components necessary for pro-IL-1ß activation (NLRP3, PYCARD, CASP1), chemokine (CCL2), leptin receptor isoforms (LEPRa, LEPRb) and a suppressor of cytokine signalling (SOCS3) in the ChP of ewes treated or not with lipopolysaccharide (LPS). Studies were conducted on adult female sheep divided into four groups (n = 6 in each): control, leptin (20 µg/kg), LPS (400 ng/kg), and LPS and leptin injected under SD and LD photoperiods. The leptin alone did not affect the gene expression but in co-treatment with LPS increased (p < 0.05) IL1B but only during SD, and SOCS3, IL1R2, IL1RN, IL6ST and CCL2 only during LD, and decreased (p < 0.05) the IL1R1 expression only during SD photoperiod. This indicates that the immunomodulatory action of leptin on the ChP is manifested only under the LPS challenge and is photoperiodically dependent.
Assuntos
Plexo Corióideo/metabolismo , Inflamassomos/metabolismo , Leptina/sangue , Fotoperíodo , Animais , Quimiocina CCL2/genética , Quimiocina CCL2/metabolismo , Plexo Corióideo/efeitos dos fármacos , Feminino , Inflamassomos/genética , Interleucina-1beta/genética , Interleucina-1beta/metabolismo , Interleucina-6/genética , Interleucina-6/metabolismo , Lipopolissacarídeos/toxicidade , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores de Interleucina/genética , Receptores de Interleucina/metabolismo , Receptores para Leptina/genética , Receptores para Leptina/metabolismo , Ovinos , Receptor 4 Toll-Like/genética , Receptor 4 Toll-Like/metabolismoRESUMO
Phenolic glycolipids (PGLs) are cell wall components of a subset of pathogenic mycobacteria, with immunomodulatory properties. Here, we show that in addition, PGLs exert antibactericidal activity by limiting the production of nitric oxide synthase (iNOS) in mycobacteria-infected macrophages. PGL-mediated downregulation of iNOS was complement receptor 3-dependent and comparably induced by bacterial and purified PGLs. Using Mycobacterium leprae PGL-1 as a model, we found that PGLs dampen the toll-like receptor (TLR)4 signaling pathway, with macrophage exposure to PGLs leading to significant reduction in TIR-domain-containing adapter-inducing interferon-ß (TRIF) protein level. PGL-driven decrease in TRIF operated posttranscriptionally and independently of Src-family tyrosine kinases, lysosomal and proteasomal degradation. It resulted in the defective production of TRIF-dependent IFN-ß and CXCL10 in TLR4-stimulated macrophages, in addition to iNOS. Our results unravel a mechanism by which PGLs hijack both the bactericidal and inflammatory responses of host macrophages. Moreover, they identify TRIF as a critical node in the crosstalk between CR3 and TLR4.
Assuntos
Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Antígenos de Bactérias/metabolismo , Glicolipídeos/metabolismo , Macrófagos/imunologia , Mycobacterium leprae/imunologia , Óxido Nítrico Sintase Tipo II/biossíntese , Receptor 4 Toll-Like/metabolismo , Animais , Parede Celular/metabolismo , Células Cultivadas , Quimiocina CXCL10/biossíntese , Interferon beta/biossíntese , Hanseníase/imunologia , Hanseníase/microbiologia , Hanseníase/patologia , Macrófagos/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Transdução de SinaisRESUMO
Toll-like receptor (TLR)-1 and TLR2 have been shown to be receptors for Mycobacterium leprae (M. leprae), yet it is unclear whether M. leprae can signal through alternative TLRs. Other mycobacterial species possess ligands for TLR4 and genetic association studies in human populations suggest that people with TLR4 polymorphisms may be protected against leprosy. Using human embryonic kidney (HEK)-293 cells co-transfected with TLR4, we demonstrate that M. leprae activates TLR4. We used human macrophages to show that M. leprae stimulation of cytokine production is diminished if pre-treated with TLR4 neutralizing antibody. TLR4 protein expression was up-regulated on macrophages derived from non-bacillus Calmette-Guerin (BCG) vaccinated healthy volunteers after incubation with M. leprae, whereas it was down-regulated in macrophages derived from BCG-vaccinated donors. Finally, pre-treatment of macrophages derived from BCG-naive donors with BCG reversed the effect of M. leprae on TLR4 expression. This may be a newly described phenomenon by which BCG vaccination stimulates "non-specific" protection to the human immune system.
Assuntos
Vacina BCG/imunologia , Macrófagos/metabolismo , Mycobacterium leprae/metabolismo , Receptor 4 Toll-Like/metabolismo , Animais , Anticorpos Monoclonais , Anticorpos Neutralizantes , Vacina BCG/farmacologia , Diferenciação Celular/imunologia , Citocinas/metabolismo , Células HEK293 , Humanos , Hanseníase/imunologia , Hanseníase/microbiologia , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Camundongos , Monócitos/efeitos dos fármacos , Monócitos/imunologia , Mycobacterium leprae/imunologia , Transdução de Sinais , Receptor 4 Toll-Like/biossíntese , Receptor 4 Toll-Like/imunologiaRESUMO
BACKGROUND: Leprosy is complicated by immunological reactions which can occur before, during and after successful completion of multidrug therapy. Genetic studies have suggested that polymorphisms in toll-like receptors (TLRs) may affect the susceptibility of an individual with leprosy to developing Type 1 reactions. OBJECTIVES: To examine the gene and protein expression of TLRs in the cutaneous lesions of leprosy Type 1 reactions at the onset of reaction and during systemic corticosteroid therapy. METHODS: Patients who were being treated for leprosy type 1 reactions with corticosteroids as part of a randomized controlled trial of corticosteroid treatment had skin biopsies performed before, during and at the end of treatment. The gene and protein expression of TLR2 and TLR4 were measured. RESULTS: We have demonstrated that the gene hARP-P0 is a suitable control gene for TLR gene expression studies in this population. The gene and protein expression of TLR2 and TLR4 were both reduced significantly during corticosteroid treatment. CONCLUSIONS: This is the first study to examine the expression of TLR2 and TLR4 in vivo in individuals experiencing leprosy Type 1 reactions. The data support the possibility of an important role for TLR2 and TLR4 in the pathogenesis of this important complication of leprosy.
Assuntos
Glucocorticoides/uso terapêutico , Hanseníase/tratamento farmacológico , Receptor 2 Toll-Like/fisiologia , Receptor 4 Toll-Like/fisiologia , Adolescente , Adulto , Análise de Variância , Antibióticos Antituberculose/uso terapêutico , DNA Complementar/biossíntese , Quimioterapia Combinada , Feminino , Expressão Gênica , Humanos , Imuno-Histoquímica , Hanseníase/genética , Hanseníase/mortalidade , Masculino , Metilprednisolona/uso terapêutico , Pessoa de Meia-Idade , Prednisolona/uso terapêutico , Receptor 2 Toll-Like/efeitos dos fármacos , Receptor 2 Toll-Like/genética , Receptor 2 Toll-Like/metabolismo , Receptor 4 Toll-Like/efeitos dos fármacos , Receptor 4 Toll-Like/genética , Receptor 4 Toll-Like/metabolismo , Adulto JovemRESUMO
Adaptive immune responses by dendritic cells (DCs) are critically controlled by Toll-like receptor (TLR) function. Little is known about modulation of TLR-specific signaling by other pathogen receptors. Here, we have identified a molecular signaling pathway induced by the C-type lectin DC-SIGN that modulates TLR signaling at the level of the transcription factor NF-kappaB. We demonstrated that pathogens trigger DC-SIGN on human DCs to activate the serine and threonine kinase Raf-1, which subsequently leads to acetylation of the NF-kappaB subunit p65, but only after TLR-induced activation of NF-kappaB. Acetylation of p65 both prolonged and increased IL10 transcription to enhance anti-inflammatory cytokine responses. We demonstrated that different pathogens such as Mycobacterium tuberculosis, M. leprae, Candida albicans, measles virus, and human immunodeficiency virus-1 interacted with DC-SIGN to activate the Raf-1-acetylation-dependent signaling pathway to modulate signaling by different TLRs. Thus, this pathway is involved in regulation of adaptive immunity by DCs to bacterial, fungal, and viral pathogens.