Perfil de expressão gênica da via de sinalização dos receptores do tipo Toll em células mononucleares do sangue periférico humanas tolerantes ao LPS

• Autor(a) principal: Mendes, Marialice Erdelyi [UNIFESP]
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UNIFESP
• Texto Completo: https://repositorio.unifesp.br/handle/11600/9929
• topic: Monócitos; Reação em cadeia da polimerase; Lipopolissacarídeos

Pre-exposure to low doses of LPS induces resistance to a lethal challenge, a phenomenon known as endotoxin tolerance. In this study, tolerance was induced in human PBMC by culturing cells with 1 ng/mL LPS for 48 h. Cells were subsequently challenged with 100 ng/mL LPS for 2, 6 and 24 h, and the expression of 84 genes encoding proteins involved in the TLR signaling pathway was evaluated at each time point by PCR array. LPS pretreatment did not modulate the expression of TLR4 and CD14 on the surface of monocytes. A gene was defined as tolerized when LPS pretreatment reversed the effect of LPS challenge on the expression of the gene or as non-tolerized when LPS pretreatment did not reverse the effects of LPS challenge. We observed impaired or attenuated signal transduction through the NF-κB, JNK, ERK and TRIF pathways, whereas expression of p38 pathway-related genes was preserved in LPStolerant cells. These results show a distinct regulation of the TLR pathway cascades during tolerance; this may account for the differential gene expression of some inflammatory mediators, such as up-regulation of IL-10 and COX2 as well as down-regulation of TNF-α and IL-12. Depending on the effect of LPSinduced gene up-regulation or down-regulation, tolerance, as a reversion of such LPS effects, may result in repression or induction of gene expression.