Systemic over-release of interleukin-17 in acute kidney injury after septic shock: Clinical and experimental evidence

- IL-17 is over-released in acute kidney injury after septic shock.
- Th17 cells is the most probable source of IL-17.
- IL-17 release is associated with poor outcome.
- IL-17 is gradually consumed at the kidney level.

In order to investigate the role of T-helper 17 (Th17) cell activation in acute kidney injury (AKI) after septic shock, a two-stage approach was used. Firstly, peripheral blood mononuclear cells (PBMCs) and CD4-lymphocytes were isolated the first 24 h after septic shock from 26 patients with AKI and 18 patients with chronic renal disease (CRD) without AKI and stimulated for the release of tumour necrosis factor-alpha (TNFα), interleukin (IL)-10, IL-17, IL-22 and interferon-gamma (IFNγ). Results were compared with 15 healthy volunteers and 13 patients with uncomplicated sepsis. Secondly, a murine model of multiple organ dysfunction (MODS) complicated with AKI and bacterial gut translocation was studied, and IL-10, IL-17, IL-22 and IFNγ were measured in kidney homogenates. IL-17 was the only cytokine produced at greater quantities from PBMCs and CD4-lymphocytes of patients with septic shock and AKI than comparators. When PBMCs of patients with septic shock and AKI were ex-vivo stimulated, intracellular staining for IL-17 was greater in CD3(+)/CD4(+)/CD196(+) cells compared to patients with septic shock and CRD. IL-17 was released at greater amounts from PBMCs of non-survivors by septic shock and AKI but not of septic shock and CRD. In the murine model of MODS, a gradual decrease of IL-17, but not of IL-10, IL-22 and IFNγ, of kidney homogenates was found indicating over-consumption. These results suggest that AKI after septic shock is driven through IL-17 release by Th17 cells; this is gradually consumed in the kidney.