'In vivo' time course of plasma myeloperoxidase levels after granulocyte colony-stimulating factor-induced stem cell mobilization

Effect of prepartum energy balance on neutrophil function following pegbovigrastim treatment in periparturient cows

Treatment with granulocyte colony-stimulating factor (G-CSF) increases polymorphonuclear cell (neutrophil) count and enhances neutrophil function in the periparturient cow. Prepartum undernutrition was hypothesized to reduce the effect of a commercially available recombinant bovine G-CSF product (pegbovigrastim) on neutrophil count and function. Hence this study was undertaken to test the effect of undernutrition for approximately 1 mo before calving on the innate immune response to pegbovigrastim. Cows (n = 99) on pasture were blocked by expected calving date and body condition score and randomly assigned in a 2 × 2 factorial design. The first factor was that cows were fed to exceed energy requirements prepartum (full feeding) or restricted to approximately 85% of prepartum energy requirements (restricted feeding). The second factor was that at approximately 7 d before expected calving date, half the cows in each feed group were injected with pegbovigrastim and the remaining half were injected with saline. Treatments were repeated on the day of calving. Blood samples were collected pre- and postcalving for complete blood count, biochemistry, and in vitro assessment of neutrophil function including phagocytosis, myeloperoxidase release, and oxidative burst. Prepartum energy restriction resulted in lower body weight, a higher proportion of cows with elevated concentrations (i.e., >0.4 mmol/L) of fatty acids, and higher average β-hydroxybutyrate concentrations before calving relative to fully fed cows. Treatment with pegbovigrastim increased the total white cell, neutrophil, lymphocyte, and monocyte counts. Pegbovigrastim treatment resulted in increased release of myeloperoxidase by neutrophils. Prepartum feeding group did not have an effect, and no feeding group × treatment interaction was observed for any of the white cell counts or functional tests. We concluded that pegbovigrastim treatment results in significant increases in neutrophil count and enhances neutrophil function as indicated by increased myeloperoxidase release. The response to pegbovigrastim was not affected by restricted prepartum energy intake.

Oxidative stress in oncohematologic diseases: an update

An increased risk of cancer in various organs has been related to oxidative stress and several studies have revealed the mechanism by which continued oxidative stress can lead to chronic inflammation, which in turn could mediate most chronic diseases including cancer. A variety of transcription factors may be activated in consequence of oxidative stress, leading to the expression of over 500 different genes, including those for growth factors, inflammatory cytokines, chemokines, cell cycle regulatory molecules and anti-inflammatory molecules. In this review, the data related to the action of oxidative stress on the onset of various oncohematologic diseases are summarized, thus bringing together some of the latest information available on the pathogenetic role of oxidative stress in cancer. The authors evaluate the most recent publications on this topic, and, in particular, show the newest evidence of a relationship between oxidative stress and hematological malignancies, such as chronic lymphocytic leukemia, Hodgkin's lymphoma, multiple myeloma and chronic Ph-negative myeloproliferative diseases. A separate section is devoted to the implications of a change of oxidative stress in patients undergoing bone marrow transplantation. Finally, particular attention is given to the new markers of oxidative stress, such as carbonyl groups, advanced glycation end products, advanced oxidation protein products and S-nitrosylated proteins, which are certainly more stable, reliable, cheaper and more easily identifiable than those already used in clinical practice. New approaches that aim to evaluate subcellular and microenvironment redox potential may be useful in developing cancer diagnostics and therapeutics.

Antioxidant intervention: a new method for improving hematopoietic reconstitution capacity of peripheral blood stem cells

In peripheral blood stem cell transplantation, bone marrow hematopoietic stem cells (BM HSCs) are collected as they are released from the hypoxic bone marrow, then infused into peripheral blood with higher oxygen concentration after mobilization. In some cases, in vitro amplification culture under normal oxygen may be required, and homing into the hypoxic bone marrow is further carried out after intravenous re-infusion, thereby resulting in constant changes in the reactive oxygen species (ROS). The high-level ROS can damage the hematopoietic reconstitution capacity of HSCs. Thus, the application of antioxidant intervention in the in vivo mobilization of BM HSC and the in vitro culture process of peripheral blood stem cells may be effective against the negative effects of ROS on BM HSC. Antioxidant intervention may also better protect the hematopoietic reconstitution capacity of HSCs, as well as improve the success rate of transplantation.

Myeloperoxidase-dependent oxidation of etoposide in human myeloid progenitor CD34+ cells

Etoposide is a widely used anticancer drug successfully used for the treatment of many types of cancer in children and adults. Its use, however, is associated with an increased risk of development of secondary acute myelogenous leukemia involving the mixed-lineage leukemia (MLL) gene (11q23) translocations. Previous studies demonstrated that the phenoxyl radical of etoposide can be produced by action of myeloperoxidase (MPO), an enzyme found in developing myeloid progenitor cells, the likely origin for myeloid leukemias. We hypothesized, therefore, that one-electron oxidation of etoposide by MPO to its phenoxyl radical is important for converting this anticancer drug to genotoxic and carcinogenic species in human CD34(+) myeloid progenitor cells. In the present study, using electron paramagnetic resonance spectroscopy, we provide conclusive evidence for MPO-dependent formation of etoposide phenoxyl radicals in growth factor-mobilized CD34(+) cells isolated from human umbilical cord blood and demonstrate that MPO-induced oxidation of etoposide is amplified in the presence of phenol. Formation of etoposide radicals resulted in the oxidation of endogenous thiols, thus providing evidence for etoposide-mediated MPO-catalyzed redox cycling that may play a role in enhanced etoposide genotoxicity. In separate studies, etoposide-induced DNA damage and MLL gene rearrangements were demonstrated to be dependent in part on MPO activity in CD34(+) cells. Together, our results are consistent with the idea that MPO-dependent oxidation of etoposide in human hematopoietic CD34(+) cells makes these cells especially prone to the induction of etoposide-related acute myeloid leukemia.