Inflammatory/haematopoietic cytokine production by human bone marrow adipocytes

Adipocytes are now considered as secretory and endocrine cells. White and brown adipocytes synthesize and secrete a variety of cytokines, among a number of peptide and non-peptide products. Some of these cytokines, particularly IL-6 and TNF-alpha, appear multifunctional since they may be involved in the control of adipose mass, inflammatory response and haematopoiesis. Bone marrow adipocytes are another abundant type of adipocytes, but their precise role in humans is poorly understood. In the present study, we demonstrate that, in contrast to non-medullary adipocytes, human bone marrow adipocytes in primary culture secrete only trace amounts of IL-1 beta and TNF-alpha, but, they secrete significant and regulated levels of IL-6. These results reinforce the concept of functional heterogeneity of adipose tissues according to their anatomical localization, and indicate that bone marrow adipocytes may contribute to the complex network of cytokines involved in the control of haematopoiesis.