Differential Effects of Steroids and Retinoids on Bovine Myelopoiesis in Vitro

Abstract

Pregnancy and parturition are associated with physiological changes caused by steroid hormones. Alterations in number, maturity, and function of polymorphonuclear leukocytes observed in dairy cows at parturition suggest a common causative relationship with steroid hormones. This study was designed to investigate the effects of progesterone, 17-β-estradiol, and hydrocortisone on the proliferation of bovine progenitor cells. An in vitro culturing system was used, and colonies were scored after 7 d of incubation. At low concentrations, 17-β-estradiol inhibited proliferation of granulocyte progenitor cells. Hydrocortisone reduced growth of granulocyte and monocyte colonies, whereas myelopoiesis was not altered by progesterone. Furthermore, we studied the effect of retinoids on colony formation of bovine bone marrow cells. All-trans-and 9-cis-retinoic acid stimulated growth of granulocyte colonies and inhibited proliferation of the monocyte lineage. The addition of the 13-cis-isomer also increased numbers of granulocyte colony-forming units. This study indicates that steroid hormones may be responsible for alterations in the bovine hematopoietic profiles observed in circulation during the postpartum period. White blood cells, especially polymorphonuclear leukocytes, which are derived from bone marrow, are an important first line defense against mastitis. Therefore, these effects of steroids might contribute to the increased susceptibility of dairy cows to Escherichia coli mastitis. We furthermore hypothesize that an important role might be attributed to retinoic acid in its regulation of bovine myelopoiesis. Modulation of myelopoiesis in favor of the granulocyte lineage during the acute-phase reaction may be an adaptive mechanism designed to increase the capacity of first-line defense to intramammary infections. Received: October 8, 2003. Accepted: November 6, 2003 Corresponding author: C. Burvenich; e-mail: Christian.Burvenich @UGent.be. 1188(Key words: steroid hormone, retinoic acid, bone marrow, myelopoiesis) Abbreviation key: cfu-G = colony-forming unit-granulocyte, cfu-GM = colony-forming unit-granulocyte and monocyte, cfu-M = colony-forming unit-monocyte, cfutotal = colony-forming unit-total myeloid, FBS = fetal bovine serum, IMDM = Iscove's modified Dulbecco's Minimal Essential, PMN = polymorphonuclear leukocytes, RAR = retinoic acid receptor, RXR = retinoid X receptor.

Evaluation of bone marrow with particular consideration of the megakaryocyte lineage and coagulation profile in the pregnant fallow deer (Dama dama)

“…Our study revealed a slight increase in erythroblast counts in the pregnant deer, but there were no differences in the lymphoid and monocyte-macrophage counts between the analysed groups. Similar findings were obtained for the lymphoid and monocyte-macrophage lineages by Van Merris et al (2004) in a study investigating bone marrow cells in cows having progesterone levels indicative of advanced pregnancy. Megakaryocyte count in the thrombopoietic system was slightly lower, and platelet count in peripheral blood was significantly lower in the pregnant animals than in non-pregnant controls.…”

“…Megakaryoblast and promegakaryocyte counts were similar in both animal groups. In a study on bovine bone marrow Van Merris et al (2004) also demonstrated a drop in megakaryocyte count during late pregnancy and parturition, with no decrease in megakaryoblast and promegakaryocyte counts.…”

“…Sasaki and Ito (1980) reported clear differences in bone marrow cell counts, and thus in peripheral blood, during the final stage of pregnancy in mice, reflected in decreased counts of lymphocytes, monocytes and platelets. Van Merris et al (2004) demonstrated the effect of steroid hormones and retinoid on myelopoiesis in cattle, and increased levels of all myelocytic lineages. An increased count of neutrophils and eosinophils, as well as increased erythrocyte counts in peripheral blood, were found in the erythroblastic system.…”

Demonstration of early functional compromise of bone marrow derived hematopoietic progenitor cells during bovine neonatal pancytopenia through in vitro culture of bone marrow biopsies

“…Cell colonies were counted and typed as CFU-GEMM, CFU-E and CFU-GM. As per previous studies [23-25] clusters of cells were considered colonies for CFU-GM when more than 40 cells were counted at day 7 and for CFU-E when more than 8 haemoglobinised cells were counted at day 5. CFU-GEMM are considered multilineage colonies with the largest number of cells but are not previously characterised in cattle; we counted colonies of greater than 10 cells at day 2 and greater than 100 cells at day 7.…”

Evaluation of bone marrow in female fallow deer kept in captivity

“…Original paper DOI: 10.21521/mw.5773 Cells that give rise to morphotic components of peripheral blood are produced in a complex process of hematopoiesis (13). The stages of hematopoiesis are identical in fallow deer and other animals, including ruminants.…”