Major surgery and the immune system: from pathophysiology to treatment

Purpose of review The purpose of this review is to provide an overview of the immune response to major surgery, and the ways in which it may be modulated to improve postoperative outcomes. Recent findings Data from patients who have undergone a variety of tissue injuries (surgery, burns, sepsis, trauma) have shown the presence of a conserved 'genomic storm' that alters the leukocyte transcriptome, with upregulation of the innate immune response and concomitant downregulation of the adaptive immune response. The innate and adaptive immune systems are often regarded largely distinct. However, more recent evidence suggests there are critical connections between the two arms of the immune response, whereby innate immune cells are able to suppress the adaptive response. The immune system is critical to the host response to tissue injury occurring due to surgery. However, the physiological processes required to resolve the surgical insult can also contribute to sequelae such as cognitive decline, pneumonia and acute kidney injury. Our understanding of the immune pathogenesis underlying these complications is improving, leading to interest in the development of immunomodulatory therapies, which aim to permit host defence whilst ameliorating postoperative complications.