RESUMO
Organ transplantation from ABO blood group-incompatible (ABOi) donors requires accurate detection, effective removal and subsequent surveillance of antidonor antibodies. Because ABH antigen subtypes are expressed differently in various cells and organs, measurement of antibodies specific for the antigen subtypes in the graft is essential. Erythrocyte agglutination, the century-old assay used clinically, does not discriminate subtype-specific ABO antibodies and provides limited information on antibody isotypes. We designed and created an ABO-glycan microarray and demonstrated the precise assessment of both the presence and, importantly, the absence of donor-specific antibodies in an international study of pediatric heart transplant patients. Specific IgM, IgG, and IgA isotype antibodies to nonself ABH subtypes were detected in control participants and recipients of ABO-compatible transplants. Conversely, in children who received ABOi transplants, antibodies specific for A subtype II and/or B subtype II antigens-the only ABH antigen subtypes expressed in heart tissue-were absent, demonstrating the fine specificity of B cell tolerance to donor/graft blood group antigens. In contrast to the hemagglutination assay, the ABO-glycan microarray allows detailed characterization of donor-specific antibodies necessary for effective transplant management, representing a major step forward in precise ABO antibody detection.
Assuntos
Sistema ABO de Grupos Sanguíneos/imunologia , Incompatibilidade de Grupos Sanguíneos/imunologia , Transplante de Coração , Tolerância Imunológica/imunologia , Isoanticorpos/imunologia , Polissacarídeos/imunologia , Linfócitos B/imunologia , Estudos de Casos e Controles , Criança , Pré-Escolar , Feminino , Seguimentos , Sobrevivência de Enxerto/imunologia , Humanos , Lactente , Recém-Nascido , Masculino , Análise em Microsséries , PrognósticoRESUMO
The human sialidase, NEU4, has emerged as a possible regulator of neuronal differentiation and its overexpression has been demonstrated to promote the acquisition of a stem cell-like phenotype in neuroblastoma cells. In this paper, we demonstrated that glioblastoma stem cells (GSCs) isolated from glioblastoma multiforme (GBM) cell lines and patients' specimens as neurospheres are specifically marked by the upregulation of NEU4; in contrast, the expression of NEU4 is very low in non-neurosphere-differentiated GBM cells. We showed that NEU4 silencing by miRNA or a chemical inhibitor of its catalytic activity triggered key events in GSCs, including (a) the activation of the glycogen synthase kinase 3ß, with the consequent inhibition of Sonic Hedgehog and Wnt/ß-catenin signalling pathways; (b) the decrease of the stem cell-like gene expression and marker signatures, evidenced by the reduction of NANOG, OCT-4, SOX-2, CD133 expression, ganglioside GD3 synthesis, and an altered protein glycosylation profile; and (c) a significant decrease in GSCs survival. Consistent with this finding, increased NEU4 activity and expression induced in the more differentiated GBM cells by the NEU4 agonist thymoquinone increased the expression of OCT-4 and GLI-1. Thus, NEU4 expression and activity appeared to help to determine the molecular signature of GSCs and to be closely connected with their survival properties. Given the pivotal role played by GSCs in GBM lethality, our results strongly suggest that NEU4 inhibition could significantly improve current therapies against this tumour.
Assuntos
Neuraminidase/metabolismo , Antígeno AC133 , Antígenos CD/genética , Antígenos CD/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular , Gangliosídeos/metabolismo , Inativação Gênica , Glioblastoma/metabolismo , Glioblastoma/patologia , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogênio Sintase Quinase 3 beta , Glicoproteínas/genética , Glicoproteínas/metabolismo , Proteínas Hedgehog/genética , Proteínas Hedgehog/metabolismo , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Humanos , MicroRNAs/genética , MicroRNAs/metabolismo , Proteína Homeobox Nanog , Células-Tronco Neoplásicas/citologia , Células-Tronco Neoplásicas/metabolismo , Neuraminidase/antagonistas & inibidores , Neuraminidase/genética , Fator 3 de Transcrição de Octâmero/genética , Fator 3 de Transcrição de Octâmero/metabolismo , Peptídeos/genética , Peptídeos/metabolismo , Fatores de Transcrição SOXB1/genética , Fatores de Transcrição SOXB1/metabolismo , Via de Sinalização WntRESUMO
Bacterial chemotactic responses are initiated when certain small molecules (i.e., carbohydrates, amino acids) interact with bacterial chemoreceptors. Although bacterial chemotaxis has been the subject of intense investigations, few have explored the influence of attractant structure on signal generation and chemotaxis. Previously, we found that polymers bearing multiple copies of galactose interact with the chemoreceptor Trg via the periplasmic binding protein glucose/galactose binding protein (GGBP). These synthetic multivalent ligands were potent agonists of Escherichia coli chemotaxis. Here, we report on the development of a second generation of multivalent attractants that possess increased chemotactic activities. Strikingly, the new ligands can alter bacterial behavior at concentrations 10-fold lower than those required with the original displays; thus, they are some of the most potent synthetic chemoattractants known. The potency depends on the number of galactose moieties attached to the oligomer backbone and the length of the linker tethering these carbohydrates. Our investigations reveal the plasticity of GGBP; it can bind and mediate responses to several carbohydrates and carbohydrate derivatives. These attributes of GGBP may underlie the ability of bacteria to sense a variety of ligands with relatively few receptors. Our results provide insight into the design and development of compounds that can modulate bacterial chemotaxis and pathogenicity.
