Extramedular Hematopoiesis in the Spleen of Obese Mice Modulation by the Alga Chlorella

Abstract

In this study, Balb/C mice received standard or high-fat diet (HFD) and were treated with Chlorella for 5 days prior and 4 weeks after the onset of HFD. Our findings demonstrate that in HFD-induced obesity, there is a rapid decline in the number of granulocyte and macrophage progenitors (CFU-GM) in the bone marrow, which is associated with a continuous migration/increase of these cells into the spleen, a process characterized as extramedullary hematopoiesis (EMH). No changes in the size of the primitive (LSK), and reduction in the size of the granulocyte/macrophage (GMP) hematopoietic populations in the bone marrow were observed. We also found that increased expression of C-C chemokine receptor type 2 (CCR2) on GMP in the spleen might be a mechanism related to the migration of CFU-GM to this organ. Increased serum colony-stimulating activity (CSA) was also found in obese mice. IL-6 serum levels, measured at the end of the treatment (12 weeks) when impaired glucose tolerance was already established [1], was increased. Treatment with Chlorella restored to normal values the numbers of CFU-GM in the marrow and spleen, the percentage of GMP in the marrow, the expression of CCR2 on spleen GMP, the increased serum levels of IL-6, and further increased CSA compared to obese mice. These findings suggest the ability of Chlorella to modulate the shift in hematopoietic topographical hierarchy, probably due its anti-inflammatory properties.