RESUMO
Infections are a major cause of childhood mortality. We investigated components of the lectin pathway of complement activation in the context of sepsis at both genetic and protein levels in neonates, infants and older children. Major components of the lectin pathway and two genes for Toll-like receptors were studied in 87 neonates with confirmed sepsis and compared with 40 babies with infections who did not develop sepsis (disease controls) and 273 infection-free neonatal controls. A second cohort comprised 47 older children with sepsis and 87 controls. Low MBL-conferring genotypes (LXA/O+O/O) were more frequent in sepsis patients than in healthy controls but no significant differences in the frequency of SNPs of other lectin pathway genes (FCN1, FCN2, FCN3, MASP1/3, MASP2) or TLR receptor genes (TLR2, TLR4) were found. One case of primary MASP-2 deficiency was found among healthy pre-terms and one neonate suffering from SIRS was heterozygous for the rare FCN1 gene mutation, +6658 G>A. Generally, sepsis was associated with low serum MBL and low ficolin-2 concentrations on admission. Among neonates, ficolin-1 and MASP-2 levels were elevated in sepsis relative to healthy, but not disease, controls. Unlike neonates, ficolin-3 and MASP-2 levels were lower in older patients than in healthy controls while no difference was found for ficolin-1. With the possible exception of MBL, inherited lectin pathway insufficiencies do not seem to predispose to sepsis, rather changes in protein concentrations reflect alterations in disease course.
Assuntos
Lectina de Ligação a Manose da Via do Complemento/imunologia , Unidades de Terapia Intensiva , Alelos , Infecções Bacterianas/genética , Infecções Bacterianas/imunologia , Infecções Bacterianas/microbiologia , Infecções Bacterianas/mortalidade , Estudos de Casos e Controles , Criança , Pré-Escolar , Ativação do Complemento , Feminino , Frequência do Gene , Genótipo , Humanos , Lactente , Lectinas/genética , Lectinas/metabolismo , Masculino , Lectina de Ligação a Manose/genética , Lectina de Ligação a Manose/imunologia , Serina Proteases Associadas a Proteína de Ligação a Manose/metabolismo , Mutação , Polimorfismo de Nucleotídeo Único , Sepse/genética , Sepse/imunologia , Sepse/microbiologia , Sepse/mortalidade , FicolinasRESUMO
Ficolin-3 (also called H-ficolin or Hakata antigen) is the most potent activator of the lectin pathway of complement in vitro. Its genetically determined deficiency in Caucasians is associated with a frame-shift mutation +1637delC (rs28357092) of the FCN3 gene. When it was described for the first time, it was postulated to be strictly associated with enhanced susceptibility to infections. At present, with our knowledge extended by several other patients that issue seems to be more complicated and less clear-cut. Two new cases of primary Ficolin-3 deficiency are reported here: a 50-year old male, suffering from membranous nephropathy and an 11-month old male infant who was operated on to repair congenital heart disease. Based on those cases and a literature review, we conclude that the clinical consequences of congenital Ficolin-3 deficiency are still unclear and such questions as whether it may be life-threatening or acts as a disease modifier remain to be elucidated.