Negative regulation of bacterial killing and inflammation by two novel CD16 ligands.

Sepsis, a leading cause of death worldwide, involves exacerbated proinflammatory responses and inefficient bacterial clearance. Phagocytic cells play a crucial part in the prevention of sepsis by clearing bacteria through host innate receptors. Here, we used a phage display library to identify two peptides in Escherichia coli that interact with host innate receptors. One of these peptides, encoded by the wzxE gene of E. coli K-12, was involved in the transbilayer movement of a trisaccharide-lipid intermediate in the assembly of enterobacterial common antigen. Peptide-receptor interactions induced CD16-mediated inhibitory immunoreceptor tyrosine-based activating motif signaling, blocking the production of ROS and bacterial killing. This CD16-mediated inhibitory signaling was abrogated in a WzxE(-/-) mutant of E. coli K-12, restoring the production of ROS and bacterial killing. Taken together, the two novel CD16 ligands identified negatively regulate bacterial killing and inflammation. Our findings may contribute toward the development of new immunotherapies for E. coli-mediated infectious diseases and inflammation.

Defectos en la síntesis de cadena ζ en el linfocito T, generando señales intracelulares equivocadas, responsables de lupus eritematoso sistémico / Defects in the synthesis of ζ chain in T lymphocytes, generating wrong intracellular signals, responsible for systemic lupus erythematosus

La expresión anormal de moléculas claves en señalización y la función defectuosa de los linfocitos T cumplen un papel significativo en la patogénesis de la enfermedad autoinmune. Las células T muestran numerosas anormalidades en la señalización del complejo TCRζ¹, estas aberraciones resultan en la alteración de la expresión de citoquinas. Mientras algunas de estas anormalidades explican el aumento de la actividad de células B por células T con incremento de los anticuerpos, la disminución en la producción de IL-2 resulta en un aumento en la susceptibilidad a las infecciones, reducción en la activación de las células T, inducción de la muerte celular y prolongada sobrevida de las células T autorreactivas².

The abnormal expression of key molecules in signaling and the malfunction of the T cell T have a significant activity in the pathogenesis of the autoimmune disease. The cells T exhibit numerous abnormalities in the signaling of the complex TCRζ¹, these aberrations result in the alteration of the citoquines. While some of these abnormalities explain the increase of the activity of cells B for cells T with increment of the antibodies production, the decrease in the production of IL-2 induces an increase in the susceptibility to the infections, diminishing in the activation of the cells T, and expansion of the lifespan of the autorreactive cells².