Insights into sepsis-induced apoptosis: Interplay between programmed cell death and interleukin-7

The pathophysiology of sepsis is orchestrated by a delicate and dynamic interaction between pro-inflammatory and anti-inflammatory responses. Essential factors influencing this process include interleukin-7 (IL-7), the programmed cell death protein 1/programmed death ligand 1 (PD-1/PD-L1) axis, and cellular apoptosis. These elements shape the immune response in sepsis, influencing its progression and outcomes. IL-7 is an important cytokine maintaining lymphocyte function and survival. At the same time, the PD-1/PD-L1 axis acts as a modulatory checkpoint suppressing immune activation to prevent overreaction but can exacerbate immunosuppression during sepsis. Cellular apoptosis impairs the host's ability to mount an effective defence, especially against secondary infections. Despite extensive research, the precise mechanisms through which sepsis results in organ dysfunction and immune dysregulation remain incompletely understood. The global burden of sepsis emphasizes the urgent need for innovative approaches, paving the way for personalized, immune-based therapies. This review aims to delve into and synthesize the current knowledge regarding cellular apoptosis, the regulatory role of the PD-1/PD-L1 axis, and the critical functions of IL-7 in sepsis, with a focus on their underlying mechanisms, clinical relevance, and potential as targets for future immunomodulatory treatments.