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.

Background: Sepsis is a dysregulated host response to an infection and can result in organ dysfunctions and death. Extracorporeal blood purification techniques aim to improve the prognosis of these patients by modulating the unbalanced immune response. This study reports our experience with the use of the oXiris® membrane for septic shock patients requiring continuous renal replacement therapy (CRRT). Summary: Thirty-one patients were diagnosed with septic shock and underwent CRRT with the oXiris® membrane between 2014 and 2019. We compared the observed hospital mortality with that predicted by the Simplified Acute Physiology Score II (SAPS II). Change in the Sequential Organ Failure Assessment (SOFA) score and of the main clinical and biological parameters over time were analyzed. Hospital mortality was lower than predicted for the most severe patients (60 vs. 91% for the [74–87] SAPS II quartile and 70 vs. 98% for the [87–163] SAPS II quartile, p < 0.02). There was no significant improvement in the SOFA score from 0h to 48 h. An 88% relative decrease in norepinephrine infusion was observed (median at 0 h was 1.69 [0.52–2.45] µg/kg/min; at 48 h it was 0.20 [0.09–1.14] µg/kg/min, p = 0.002). Lactataemia and pH were significantly improved over time. Patients with intra-abdominal sepsis as well as those with Gram-negative bacilli (GNB) infections seemed to benefit the most from the therapy. Key Messages: CRRT with the oXiris® haemofilter resulted in higher observed survival than predicted by a severity score (SAPS II) for the most severe patients. Haemodynamic status and lactataemia appeared to improve, especially in intra-abdominal sepsis and GNB infections.