Natural killer cells in sepsis: Friends or foes?

Sepsis is one of the major causes of death in the hospital worldwide. The pathology of sepsis is tightly associated with dysregulation of innate immune responses. The contribution of macrophages, neutrophils, and dendritic cells to sepsis is well documented, whereas the role of natural killer (NK) cells, which are critical innate lymphoid lineage cells, remains unclear. In some studies, the activation of NK cells has been reported as a risk factor leading to severe organ damage or death. In sharp contrast, some other studies revealed that triggering NK cell activity contributes to alleviating sepsis. In all, although there are several reports on NK cells in sepsis, whether they exert detrimental or protective effects remains unclear. Here, we will review the available experimental and clinical studies about the opposing roles of NK cells in sepsis, and we will discuss the prospects for NK cell-based immunotherapeutic strategies for sepsis.

Automated summary

Sepsis is a leading cause of hospital deaths worldwide and is associated with dysregulation of innate immune responses. While the roles of macrophages, neutrophils, and dendritic cells in sepsis are well-known, the contribution of natural killer (NK) cells, a critical type of innate lymphoid cells, remains unclear. Some studies suggest that NK cell activation is a risk factor for severe organ damage or death, while others indicate that triggering NK cell activity helps alleviate sepsis. This review discusses the conflicting roles of NK cells in sepsis based on experimental and clinical studies and explores the prospects of NK cell-based immunotherapeutic strategies for sepsis.