The prognostic value of leukocyte apoptosis in patients with severe sepsis at the emergency department

Survivin and caspases serum protein levels and survivin variants mRNA expression in sepsis

Sepsis is a dysregulated host response to infection related to devastating outcomes. Recently, interest has been shifted towards apoptotic and antiapoptotic pathobiology. Apoptosis is executed through the activation of caspases regulated by a number of antiapoptotic proteins, such as survivin. The survivin and caspases’ responses to sepsis have not yet been elucidated. This is a multicenter prospective observational study concerning patients with sepsis (n = 107) compared to patients with traumatic systemic inflammatory response syndrome (SIRS) (n = 75) and to healthy controls (n = 89). The expression of survivin was quantified through real-time quantitative polymerase chain reaction for the different survivin splice variants (wild type-WT, ΔEx3, 2B, 3B) in peripheral blood leukocytes. The apoptotic or antiapoptotic tendency was specified by measuring survivin-WT, caspase-3, and -9 serum protein concentrations through enzyme-linked immunosorbent assay. The survivin-WT, -2B, -ΔΕx3 mRNA, survivin protein, and caspases showed an escalated increase in SIRS and sepsis, whereas survivin-3B was repressed in sepsis (p < 0.05). Survivin correlated with IL-8 and caspase-9 (p < 0.01). For discriminating sepsis, caspase-9 achieved the best receiver operating characteristic curve (AUROC) of 0.95. In predicting mortality, caspase-9 and survivin protein achieved an AUROC of 0.70. In conclusion, specific apoptotic and antiapoptotic pathways might represent attractive targets for future research in sepsis.

Impact of oxidative stress on treatment outcomes in adult patients with sepsis: A prospective study

PURPOSE

Oxidative stress has been shown to reflect on the development of sepsis and disease severity. In the present study, we evaluated the effects of increased levels of oxidative stress and decreased antioxidant coactivity in patients with sepsis, and the importance of oxidative stress on treatment outcomes.

METHODS

Biomarkers of oxidative stress (thiobarbituric acid-reactive substances [TBARS]) and antioxidant capacity (glutathione peroxidase [GPx] and glutathione content [thiol]) were prospectively evaluated along with biochemical and clinical data in 100 patients with sepsis on days 1, 4, and 7 after admission.

RESULTS

The TBARS level of the non-survivor group was significantly higher than that of the survivor group on day 1 and day 4 and negatively correlated with thiol upon admission. However, thiol was positively correlated with lactate concentration. The TBARS and lactate levels upon admission were independent predictors of fatality.

CONCLUSIONS

We conclude that a TBARS cut-off value of 18.30 μM can be used to predict fatality, and an increase in the TBARS concentration by 1 μM will increase the fatality rate by 0.94%. In the panel of biomarkers, the TBARS assay can be considered as a prognostic biomarker for the treatment of patients with sepsis.

Biomarkers of Immunosuppression

It is now recognized that sepsis is not a uniformly proinflammatory state. There is a well-recognized counter anti-inflammatory response that occurs in many patients. The timing and magnitude of this response varies considerably and thus makes its identification and manipulation more difficult. Studies in animals and humans have now identified a small number of biologic responses that characterize this immunosuppressed state, such as lymphocyte death, HLA receptor downregulation, and monocyte exhaustion. Researchers are now trying to use these as markers of individual immunosuppression to predict outcomes and identify patients who would and would not benefit from new immune stimulatory therapies.

Apoptosis-induced lymphopenia in sepsis and other severe injuries

Sepsis and other acute injuries such as severe trauma, extensive burns, or major surgeries, are usually followed by a period of marked immunosuppression. In particular, while lymphocytes play a pivotal role in immune response, their functions and numbers are profoundly altered after severe injuries. Apoptosis plays a central role in this process by affecting immune response at various levels. Indeed, apoptosis-induced lymphopenia duration and depth have been associated with higher risk of infection and mortality in various clinical settings. Therapies modulating apoptosis represent an interesting approach to restore immune competence after acute injury, although their use in clinical practice still presents several limitations. After briefly describing the apoptosis process in physiology and during severe injuries, we will explore the immunological consequences of injury-induced lymphocyte apoptosis, and describe associations with clinically relevant outcomes in patients. Therapeutic perspectives targeting apoptosis will also be discussed.