Toll-like receptor pathway signaling is differently regulated in neurophils and peripheral mononuclear cells of patients with sepsis, severe sepsis and septic shock

Background

Upregulation and downregulation of inflammatory response was described in blood cells from septic patients, according to the stage of sepsis and the cells evaluated. This study aimed to evaluate the Toll-like receptor (TLR) signaling pathway gene expression in peripheral blood mononuclear cells (PBMC) and neutrophils in patients throughout the different stages of sepsis.

Methods

Septic patients admitted to two emergency rooms and two ICUs in one university and one teaching hospital were enrolled in the study, including five with sepsis, five with severe sepsis and five with septic shock. Five healthy volunteers were enrolled as controls. The Human-TLR Signaling Pathway, which comprises 84 genes related to TLR-mediated signal transduction, was evaluated by real-time PCR in PBMC and neutrophils obtained from patients and controls. Results were expressed as CT and were normalized with the housekeeping gene 18SrRNA (ΔCT). The fold change for each gene (2^-ΔΔCT) was compared between the groups. Genes with fold changes greater than two and significant changes in ΔCT are reported as differently expressed.

Results

The fold change ratios in PBMC gene expression between septic patients and healthy controls revealed a dynamic process according to the stage of sepsis, tending towards downregulation of the TLR signaling pathway in PBMC in the more severe forms of the disease. In patients with sepsis and severe sepsis, fold-change analyses showed upregulated genes mostly in TLR receptors and adaptor or TLR interacting protein groups. The downregulated genes consisted mostly of downstream pathways and target genes, and they included the NFκB, JNK/p38 pathway, and effectors. However, the differential gene expression was restricted to five downregulated genes in septic shock patients, which are found in the effector and downstream pathways. Neutrophils showed a different pattern of adaptation. Patients with sepsis, severe sepsis and septic shock presented a broad gene upregulation, which included all functional groups evaluated and persisted throughout the stages of the disease.

Conclusion

TLR-signaling pathway genes are differently regulated in PBMC and neutrophils of septic patients, and are dynamically modulated throughout the different stages of sepsis.