The Role of Gut Microbiota in Acute Myeloid Leukemia

Gut microbiota plays a crucial role in regulating immune system function and shaping immunological responses to pathogens capable of causing infections. Alterations in the composition of the intestinal microbiome are associated with immune system dysfunction and increased susceptibility to infections. Patients with acute myeloid leukemia (AML) are highly susceptible to infections due to immune system deregulation caused by the disease itself, as well as chemotherapy-induced bone marrow aplasia. In these patients, gut microbiota dysbiosis and reduced microbial diversity (i.e., imbalances in the composition and function of intestinal microbes) result from multiple factors, including the underlying disease, neutropenia, dietary factors, use of antibiotics, chemotherapy regimens and prolonged hospitalization. Chemotherapy, for instance, induces damage to the intestinal mucosa and disrupts the epithelial barrier, resulting in deregulation of the intestinal microbiome. Previous studies have reported alterations in the human intestinal microbiome in patients with AML undergoing chemotherapy. Of particular interest is the capacity of some commensal bacteria to modulate the tumor microenvironment and response to chemotherapy. Moreover, increased mortality and reduced overall survival have been reported in patients who have undergone allogeneic stem cell transplantation and exhibit decreased gut microbiome diversity at the time of transplantation. These findings indicate that the composition of gut microbiota may play an important role in the prognosis of AML, especially in relation to therapeutic response. This narrative review summarizes new research into the role of the intestinal microbiome and the underlying alterations observed in patients with AML, resulting from the disease and therapeutic interventions and outlines strategies to improve its function and outcomes.