The Gastro-Intestinal Microbiota in Haematology

(1) The gut microbiota influences haematopoiesis via immune signalling, microbial metabolites, and maintenance of mucosal barrier function. (2) Dysbiosis is associated with CHIP, leukaemias, and PCN, and may contribute through chronic inflammation and altered immune homeostasis. (3) Haematological therapies frequently reshape the microbiota; these changes may affect infection risk, treatment tolerance, and outcomes. (4) Current evidence is largely associative; rigorously designed longitudinal and interventional studies are needed to establish causality and guide clinical translation.