Upregulation of the pro-apoptotic genes BID and FAS in septic shock patients

Abstract

IntroductionLymphocyte apoptosis has been suggested to play a central role in sepsis pathophysiology, and studies in animal models demonstrated that blocking this pathway improves outcome. However, no routine biomarkers of apoptosis are so far available in patients. Thus, the aim of our study was to assess the different biomarkers of apoptosis putatively usable on a routine basis in septic shock.MethodsThirteen septic shock patients (sampled twice between days 1 to 2 and days 3 to 5 after diagnosis of shock) and 15 sex-matched and age-matched healthy controls were prospectively enrolled. Apoptosis was measured in lymphocyte subpopulations using flow cytometry (Annexin-V binding, activated caspase-3 and Bcl-2 expressions). Representative pro-apoptotic and anti-apoptotic gene expressions were assessed by quantitative reverse-transcription PCR. Monocyte HLA-DR expression and lymphocyte subpopulation cell counts were measured as markers of sepsis-induced immune dysfunctions. To test for statistical significance, the Mann-Whitney U test was used with correction by the number of tests performed.ResultsFlow cytometric measurements of apoptosis in septic shock patients showed an increased Annexin-V binding on CD4+ T cells and an increased active caspase-3 expression on B cells only at days 3 to 5 (sixfold change and twofold change, respectively). Gene expression analysis showed an increased BCL-XL mRNA and an upregulation of the pro-apoptotic genes BID and FAS in septic shock patients (10-fold change and fivefold change, respectively) compared with healthy controls.ConclusionsThe present study highlights the difficulties encountered in monitoring apoptosis on a routine basis in septic patients, whereas in the same sampling conditions and on the same patients, HLA-DR expression and lymphocyte subpopulation cell counts showed characteristics described in the literature. However, pro-apoptotic genes BID and FAS appear to constitute promising apoptosis markers in our hands.

The CD95/CD95L pathway is involved in phagocytosis-induced cell death of monocytes and may account for sustained inflammation in neonates

“…This is in line with data showing elevated CD95L mRNA (19) and protein levels (27) after infection of PBMOs, and with data from adult patients showing elevated CD95L levels during the course of sepsis (26). The relevance of CD95-signaling for termination of inflammation demonstrated here (Figure 3) has been demonstrated in a mouse model of bacteria-induced acute lung injury.…”

“…This effect has already been shown for in vitro infection models of monocytes/macrophage phagocytosis with a variety of other pathogens such as Chlamydia trachomatis (23), Streptococcus pneumoniae (24), or yeast wall-prepared zymosan (15). Moreover, two studies with sera from patients suffering from severe infections, i.e., sepsis, pneumonia, or urinary tract infection, also exhibited apoptosisinducing capacity when tested in an in vitro cell culture system (25,26). Of note, in the experiments presented here, even cellculture medium inoculated with E. coli only and conditioned in the absence of cells was capable of inducing apoptosis, although no bacteria could be cultivated from it (Figure 1).…”

Bid regulates the immunological profile of murine microglia and macrophages

“…In addition, enhanced Bid expression was shown to be associated with septic shock in human patients (Turrel-Davin et al, 2010). To further examine the effect of Bid on microglial activation in vivo in a physiological relevant system, we employed systemic inflammation, in which mice are injected intraperitoneally with LPS.…”

Post-operative infection and sepsis in humans is associated with deficient gene expression of γc cytokines and their apoptosis mediators

“…In addition, there is evidence from animal sepsis models that manipulation of these regulators of apoptosis may improve outcome [40-42]. However, we noted that Bcl-2 and related genes were also dysregulated in patients with infection, but to a lesser extent than in septic patients.…”