RESUMEN
Natural killer (NK) cell activation depends on the signaling balance of activating and inhibitory receptors. CD94 forms inhibitory receptors with NKG2A and activating receptors with NKG2E or NKG2C. We previously demonstrated that CD94-NKG2 on NK cells and its ligand Qa-1b are important for the resistance of C57BL/6 mice to lethal ectromelia virus (ECTV) infection. We now show that NKG2C or NKG2E deficiency does not increase susceptibility to lethal ECTV infection, but overexpression of Qa-1b in infected cells does. We also demonstrate that Qa-1b is down-regulated in infected and up-regulated in bystander inflammatory monocytes and B cells. Moreover, NK cells activated by ECTV infection kill Qa-1b-deficient cells in vitro and in vivo. Thus, during viral infection, recognition of Qa-1b by activating CD94/NKG2 receptors is not critical. Instead, the levels of Qa-1b expression are down-regulated in infected cells but increased in some bystander immune cells to respectively promote or inhibit their killing by activated NK cells.
Asunto(s)
Linfocitos B/inmunología , Citotoxicidad Inmunológica/inmunología , Virus de la Ectromelia/inmunología , Antígenos de Histocompatibilidad Clase I/inmunología , Células Asesinas Naturales/inmunología , Virosis/inmunología , Animales , Linfocitos B/metabolismo , Linfocitos B/virología , Efecto Espectador/inmunología , Citotoxicidad Inmunológica/genética , Virus de la Ectromelia/fisiología , Antígenos de Histocompatibilidad Clase I/genética , Antígenos de Histocompatibilidad Clase I/metabolismo , Células Asesinas Naturales/metabolismo , Células Asesinas Naturales/virología , Masculino , Ratones Endogámicos C57BL , Ratones Noqueados , Subfamília C de Receptores Similares a Lectina de Células NK/genética , Subfamília C de Receptores Similares a Lectina de Células NK/inmunología , Subfamília C de Receptores Similares a Lectina de Células NK/metabolismo , Subfamília D de Receptores Similares a Lectina de las Células NK/genética , Subfamília D de Receptores Similares a Lectina de las Células NK/inmunología , Subfamília D de Receptores Similares a Lectina de las Células NK/metabolismo , Virosis/virologíaRESUMEN
Genetic variations mapping to 3' untranslated regions (3'UTRs) may overlap with microRNA (miRNA) binding sites, therefore potentially interfering with translation inhibition or messenger RNA (mRNA) degradation. The aim of this study was to investigate whether single nucleotide polymorphisms (SNPs) located within the 3'UTRs of six candidate genes and predicted to interfere with miRNA ligation could account for disease-relevant differential mRNA levels. Focusing on pemphigus foliaceus (PF) - an autoimmune blistering skin condition with unique endemic patterns - we investigated whether nine 3'UTR SNPs from the CD1D, CTLA4, KLRD1, KLRG1, NKG7, and TNFSF13B genes differentially expressed in PF were disease-associated. The heterozygous genotype of the KLRG1 rs1805672 polymorphism was associated with increased predisposition to PF (A/G vs. A/A: P=0.038; OR=1.60), and a trend for augmented susceptibility was observed for carriers of the G allele (P=0.094; OR=1.44). In silico analyses suggested that rs1805672 G allele could disrupt binding of miR-584-5p, and indicated rs1805672 as an expression Quantitative Trait Locus (eQTL), with an effect on KLRG1 gene expression. Dual-luciferase assay showed that miR-584-5p mediated approximately 50% downregulation of the reporter gene's activity through the 3'UTR of KLRG1 harboring rs1805672 A allele (vs. miRNA-negative condition, P=0.006). This silencing relationship was lost after site-directed mutation to G allele (vs. miRNA-negative condition, P=0.391; vs. rs1805672 A allele, P=0.005). Collectively, these results suggest that a disease-associated SNP located within the 3'UTR of KLRG1 directly interferes with miR-584-5p binding, allowing for KLRG1 mRNA differential accumulation, which in turn may contribute to pathogenesis of autoimmune diseases, such as pemphigus.
Asunto(s)
Regiones no Traducidas 3' , Predisposición Genética a la Enfermedad , Lectinas Tipo C/genética , MicroARNs/genética , Pénfigo/genética , Polimorfismo de Nucleótido Simple , Transactivadores/genética , Alelos , Antígenos CD1d/genética , Antígenos CD1d/metabolismo , Factor Activador de Células B/genética , Factor Activador de Células B/metabolismo , Secuencia de Bases , Sitios de Unión , Antígeno CTLA-4/genética , Antígeno CTLA-4/metabolismo , Estudios de Casos y Controles , Análisis Mutacional de ADN , Regulación de la Expresión Génica , Frecuencia de los Genes , Haplotipos , Humanos , Lectinas Tipo C/metabolismo , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , MicroARNs/metabolismo , Mutación , Subfamília D de Receptores Similares a Lectina de las Células NK/genética , Subfamília D de Receptores Similares a Lectina de las Células NK/metabolismo , Pénfigo/diagnóstico , Pénfigo/metabolismo , Pénfigo/patología , Receptores Inmunológicos , Transactivadores/metabolismoRESUMEN
To investigate CD8+ regulatory T cell influence on multiple sclerosis development, peripheral blood and cerebrospinal fluid (CSF) CD8+ T cell clones (TCCs) recognizing MBP(83-102) and MOG(63-87)-specific CD4+ T cells were isolated from 20 patients during acute exacerbations, 15 in remission and 15 controls. Blood and CSF CD8+ regulatory TCC cloning frequency decreased more during exacerbations than remissions or controls. Target cell pre-activation significantly enhanced CD8+ T granule-mediated cell killing of CD4+ targets, and was restricted by HLA-E. During exacerbations, killer-inhibitory receptor CD94/NKG2A expression was significantly higher in CD8+ TCCs, limiting their cytotoxic activity. Moreover, IL-15 and IFN-gamma significantly increased CD94 and NKG2A expression. These data provide evidence that CD94/NKG2A receptors play an important role in regulating T cell activity during the course of MS.