Inflammatory cytokines and depression symptoms following hematopoietic cell transplantation

Increased synthesis and release of inflammatory signalling proteins is common among individuals with hematologic malignancies undergoing hematopoietic cell transplantation (HCT) due to intensive conditioning regimens and complications such as graft-versus-host-disease and infections. Prior research indicates that inflammatory responses can activate central nervous system pathways that evoke changes in mood. This study examined relationships between markers of inflammatory activity and depression symptoms following HCT. Individuals undergoing allogeneic (n = 84) and autologous (n = 155) HCT completed measures of depression symptoms pre-HCT and 1, 3, and 6 months post-HCT. Proinflammatory (IL-6, TNF-α) and regulatory (IL-10) cytokines were assessed by ELISA in peripheral blood plasma. Mixed-effects linear regression models indicated that patients with elevated IL-6 and IL-10 reported more severe depression symptoms at the post-HCT assessments. These findings were replicated when examining both allogeneic and autologous samples. Follow-up analyses clarified that relationships were strongest for neurovegetative, rather than cognitive or affective, symptoms of depression. These findings suggest that anti-inflammatory therapeutics targeting an inflammatory mediator of depression could improve quality of life of HCT recipients.