Effects of monocyte-macrophage colony-stimulating factor (M-CSF) on in vitro erythropoiesis of marrow progenitor cells from patients with renal anemia

Association of plasma macrophage colony-stimulating factor with cardiovascular morbidity and all-cause mortality in chronic hemodialysis patients

Background

Cardiovascular disease (CVD) events are the main cause of death in long-term hemodialysis (HD) patients. Macrophage colony- stimulating factor (M-CSF) is actively involved in the formation of atherosclerosis and causes plaque instability, thrombosis and the development of acute coronary syndromes. However, little information is available on the role of M-CSF in HD patients. We aimed to investigate the association between plasma M-CSF levels and CVD events as well as all-cause mortality in patients undergoing long-term HD.

Methods

Fifty two HD patients and 8 healthy controls were recruited in this study. HD patients were followed up from September 2014 to May 2017. The primary end point was CVD event, the secondary outcome was death from any cause. Patients were divided into two groups with low and high M-CSF levels based on the optimal cut-off value determined by the ROC curve. Cox regression analyses were used to assess the predictive value of plasma M-CSF for CVD events and all-cause mortality in HD patients. We tested the levels of plasma M-CSF and other inflammatory cytokines in surviving HD patients using ELISA or CBA kit.

Results

The average plasma level of M-CSF in 52 patients was approximately twice that of healthy controls (992.4 vs. 427.2 pg/mL; p <  0.05). During 32 months of follow-up, 26 patients (50.0%) had at least one CVD event and 8 patients (15.4%) died. The mean plasma M-CSF concentration increased in survivors after follow-up compared to that detected at baseline (1277.8 ± 693.3 vs. 997.2 ± 417.4 pg/mL; p <  0.05). Multivariate Cox regression analysis showed that plasma M-CSF is an independent risk factor for CVD events in HD patients (p <  0.05). In the Cox regression model after adjusting for gender and age, high M-CSF levels were related to an increased risk of all-cause death (p <  0.05). We also found that M-CSF levels were positively correlated with IL-6 and IL-18 levels (both p < 0.05), which are the major pathogentic cytokines that contribute to HD-related CVD events.

Conclusion

M-CSF is a prognostic factor for CVD events and all-cause mortality in HD patients.

In vitro expansion of human cord blood CD36+ erythroid progenitors: temporal changes in gene and protein expression

OBJECTIVE

Erythropoiesis involves proliferation and differentiation of committed erythroid progenitors to mature red blood cells. The objective of this study was to characterize growth characteristics of human CD36+ erythroid progenitors and to profile temporal expression of lineage-specific transcription factors, structural proteins, and growth factor receptors involved in erythropoiesis.

MATERIALS AND METHODS

Erythropoietin-induced differentiation of human cord blood CD36+ erythroid progenitors was profiled for GATA-1, GATA-2, NFE2, EKLF, SCL, PU.1, Id1, Evi-1, c-myb, Hox2.2, c-kit, EpoR, glycophorin A (GPA), CD71, beta- and gamma-globin, and protein 4.2 gene and/or protein expression and DNA content analysis on days 4, 7, and 15 of culture.

RESULTS

Real-time RT-PCR analysis revealed upregulation of GATA-1, Id1, glycophorin A, and protein 4.2 mRNA expression on day 7 when compared to day 4 and decreased expression on day 15. EKLF, GATA-2, Hox2.2, c-myb, Evi-1, c-kit, and PU.1 mRNA expression decreased on days 7 and 15. NFE2, CD71, SCL, and EPO-R mRNA expression remained similar on days 4 and 7 but decreased on day 15. Expression of globin genes beta- and gamma-globin increased on both day 7 and day 15 compared to day 4. Values from flow cytometric quantitation of glycophorin A, transferrin receptor (CD71), and hemoglobin A proteins correlated with gene expression results. DNA analysis demonstrated that most cells lacked DNA content by day 15, a finding consistent with enucleation and terminal erythroid differentiation.

CONCLUSION

These data indicate that in vitro liquid cultures of committed CD36+ erythroid progenitor cells retain, in part, many features of erythropoiesis at the cellular and molecular level and may provide a useful model for assessment of disease-related or drug-induced erythropoietic abnormalities.

CD137 Induces Proliferation and Endomitosis in Monocytes

Peripheral monocytes are short-lived and are replenished from hematopoietic stem cells whose proliferation is believed to be confined to the bone marrow. Human peripheral monocytes are assumed not to be able to proliferate. In this study we show that CD137 (ILA/4-1BB), a member of the tumor necrosis factor receptor family, induces a widespread and profound proliferation of human peripheral monocytes. Macrophage colony-stimulating factor and granulocyte-macrophage colony-stimulating factor are essential, but not sufficient for proliferation. Additional soluble autocrine factors induced by CD137 are required. Induction of proliferation is mediated via reverse signaling through a CD137 ligand, expressed constitutively by peripheral monocytes. The ability of CD137 to induce proliferation in human peripheral monocytes is not shared by any other known molecule.

CD137 Induces Proliferation and Endomitosis in Monocytes

Peripheral monocytes are short-lived and are replenished from hematopoietic stem cells whose proliferation is believed to be confined to the bone marrow. Human peripheral monocytes are assumed not to be able to proliferate. In this study we show that CD137 (ILA/4-1BB), a member of the tumor necrosis factor receptor family, induces a widespread and profound proliferation of human peripheral monocytes. Macrophage colony-stimulating factor and granulocyte-macrophage colony-stimulating factor are essential, but not sufficient for proliferation. Additional soluble autocrine factors induced by CD137 are required. Induction of proliferation is mediated via reverse signaling through a CD137 ligand, expressed constitutively by peripheral monocytes. The ability of CD137 to induce proliferation in human peripheral monocytes is not shared by any other known molecule.

Role of the macrophage in erythropoiesis

Macrophages, which are derived from precursor cells in the bone marrow, differentiate specifically under the influence of the local microenvironment. Resident macrophages in hematopoietic tissues can be distinguished from other stromal cells and monocytes by immunostaining with monoclonal antibody F4/80 and anti-Forssman glycosphingolipid antibody, respectively. Erythroid colony-forming units adhere to a resident macrophage and differentiate to erythroblasts in the presence of erythropoietin (EPO), resulting in the formation of an erythroblastic island. Resident macrophages play a supportive role in erythropoiesis, probably by preventing apoptosis of the erythroid precursors via adhesive interaction between very late activation antigen 4 and vascular cell adhesion molecule 1. Herein is proposed a model of erythropoiesis based on cooperative interaction between EPO and resident macrophages.