Neutrophil kinetics shortly after initial administration of recombinant human granulocyte colony-stimulating factor: neutrophil alkaline phosphatase activity as an endogenous marker

A physiological model of granulopoiesis to predict clinical drug induced neutropenia from in vitro bone marrow studies: with application to a cell cycle inhibitor

Neutropenia is one of the most common dose-limiting toxocities associated with anticancer drug therapy. The ability to predict the probability and severity of neutropenia based on in vitro studies of drugs in early drug development will aid in advancing safe and efficacious compounds to human testing. Toward this end, a physiological model of granulopoiesis and its regulation is presented that includes the bone marrow progenitor cell cycle, allowing for a mechanistic representation of the action of relevant anticancer drugs based on in vitro studies. Model development used data from previously reported tracer kinetic studies of granulocyte disposition in healthy humans to characterize the dynamics of neutrophil margination in the presence of endogenous granulocyte-colony stimulating factor (G-CSF). In addition, previously published data from healthy volunteers following pegfilgrastim and filgrastim were used to quantify the regulatory effects of support G-CSF therapies on granulopoiesis. The model was evaluated for the cell cycle inhibitor palbociclib, using an in vitro system of human bone marrow mononuclear cells to quantify the action of palbociclib on proliferating progenitor cells, including its inhibitory effect on G1 to S phase transition. The in vitro results were incorporated into the physiological model of granulopoiesis and used to predict the time course of absolute neutrophil count (ANC) and the incidence of neutropenia observed in three previously reported clinical trials of palbociclib. The model was able to predict grade 3 and 4 neutropenia due to palbociclib treatment with 86% accuracy based on in vitro data.

TLR2 agonism reverses chemotherapy-induced neutropenia in Macaca fascicularis

Neutropenia is a common consequence of radiation and chemotherapy in cancer patients. The resulting immunocompromised patients become highly susceptible to potentially life-threatening infections. Granulocyte colony-stimulating factor (G-CSF) is known to stimulate neutrophil production and is widely used as a treatment of chemotherapy-induced neutropenia. A small-molecule G-CSF secretagogue without a requirement for refrigerated supply chain would offer a more convenient and cost-effective treatment of chemotherapy-induced neutropenia. Bacterial lipopeptides activate innate immune responses through Toll-like receptor 2 (TLR2) and induce the release of cytokines, including G-CSF, from macrophages, monocytes, and endothelial. Pam₂CSK₄ is a synthetic lipopeptide that effectively mimics bacterial lipoproteins known to activate TLR2 receptor signaling through the TLR2/6 heterodimer. Substrate-based drug design led to the discovery of GSK3277329, which stimulated the release of G-CSF in activated THP-1 cells, peripheral blood mononuclear cells, and human umbilical vein endothelial cells. When administered subcutaneously to cynomolgus monkeys (Macaca fascicularis), GSK3277329 caused systemic elevation of G-CSF and interleukin-6 (IL-6), but not IL-1β or tumor necrosis factor α, indicating a selective cytokine-stimulation profile. Repeat daily injections of GSK3277329 in healthy monkeys also raised circulating neutrophils above the normal range over a 1-week treatment period. More importantly, repeated daily injections of GSK3277329 over a 2-week period restored neutrophil loss in monkeys given chemotherapy treatment (cyclophosphamide, Cytoxan). These data demonstrate preclinical in vivo proof of concept that TLR2 agonism can drive both G-CSF induction and subsequent neutrophil elevation in the cynomolgus monkey and could be a therapeutic strategy for the treatment of chemotherapy-induced neutropenia.

Effects of Granulocyte Colony-Stimulating Factor (G-CSF) on Bleomycin-Induced Lung Injury of Varying Severity

We evaluated the effects of granulocyte colony-stimulating factor (G-CSF) on bleomycin (BLM)-induced lung injury that developed diffuse alveolar damage and subsequent pulmonary fibrosis (PF) of varying severity. G-CSF (100 μg/kg/day) was administered subcutaneously to BLM (0.2, 20, 2,000 μg)-treated or -untreated rats for 3 or 14 days. In the BLM 0.2 μg group, slight alveolar mononuclear cell infiltration was observed, although PF was not noted. In the BLM 20- μg and 2,000- μg groups, diffuse alveolar damage along with neutrophil infiltration and subsequent PF were observed. In the saline + G-CSF group and BLM 0.2 μg + G-CSF group, a marked increase in the number of alkaline phosphatase (ALP)-positive neutrophils was noted in the alveolar capillaries, although there was neither neutrophil infiltration in alveoli nor exacerbation of lung injury. In the BLM 20 μg + G-CSF and BLM 2,000 μg + G-CSF groups, an exacerbation of lung injury along with an increase in the number of ALP-positive neutrophils in the alveoli was observed. These results indicate that the administration of G-CSF to rats with slight lung injury bearing no PF does not exacerbate the lung injury. The exacerbating effects of G-CSF seem to be associated not only with the marked infiltration of activated neutrophils but also with the severity of underlying lung injury.

Effects of granulocyte colony-stimulating factor on the kinetics of inflammatory cells in the peripheral blood and pulmonary lesions during the development of bleomycin-induced lung injury in rats

We evaluated the effects of granulocyte colony-stimulating factor (G-CSF) on the kinetics of inflammatory cells during the development of inflammation in bleomycin (BLM)-induced lung injury. G-CSF (100 microg/kg/day, s.c.) was administered to rats treated with or without BLM (2 mg/200 microl, intratracheally) for up to 14 days (Day 14) immediately after BLM treatment. In the BLM + G-CSF group, the lung injury score increased on Days 1 and 14, and the score of lung fibrosis on Day 14, respectively. Except for neutrophils, there were no effects of G-CSF on the number of inflammatory cells both in the peripheral blood and in the lung in both BLM-treated and -untreated rats at the acute inflammatory phase. In the G-CSF-treated groups, the number of neutrophil counts in the peripheral blood drastically increased on Day 1, temporally decreased on Day 3, and increased again on Days 7 and 14. The number of neutrophils in the lung markedly increased on Day 1 and then remained at a plateau level until Day 14. The neutrophil alkaline phosphatase score in the lung commenced to increase on Day 1, reached the maximal level on Day 7, and then remained at a plateau level until Day 14. Correlations between the numbers of neutrophils in the lung and the peripheral blood or the lung lesion score were only observed on Day 14. These findings suggest that the exacerbating effect of G-CSF on the lung injury coincided with the increase in the number of alkaline phosphatase-positive neutrophils infiltrating in the pulmonary lesion at the acute inflammatory phase and it lasted to the fibrogenic phase. The exacerbating effect of G-CSF on the severe BLM-induced lung injury seems to be related not only to the pulmonary accumulation of activated neutrophils but also to the severity of lung injury caused by the direct effects of BLM.

Macrophage colony-stimulating factor (M-CSF) prevents infectious death induced by chemotherapy in mice, while granulocyte-CSF does not

To clarify the effect of granulocyte colony-stimulating factor (G-CSF) and macrophage colony-stimulating factor (M-CSF/CSF-1) on chemotherapy-induced infection, we estimated the effect of those CSFs on a mouse model under severe myelosuppression. First, we established an animal model in which 48.9% (22/45) of C3H/Hej mice died of sepsis related to severe myelosuppression after intraperitoneal administration of a single dose (9 mg/kg) of mitomycin C (MMC). G-CSF or M-CSF was administered to this model on various administration schedules after chemotherapy, and the effect of those CSFs on survival rates, peripheral blood granulocyte counts, expression of adhesion molecules (CD11a, CD11b, CD18) on granulocytes and granulocyte function (phagocytosis and superoxide anion production) were examined. In all G-CSF administration groups, peripheral blood granulocyte counts were increased, but improvements in expression of adhesion molecules such as CD11a and CD18, and granulocyte function were less marked and survival rates were not improved. Meanwhile, when M-CSF was administered from 1 to 7 days after chemotherapy, granulocyte and platelet counts were increased, and moreover, expression of adhesion molecules and granulocyte function were markedly improved. Furthermore, the survival rate was significantly improved to 77.8% (28/36) compared with the MMC group (P < 0.05). Positive rate of blood culture examination at 7 days after chemotherapy in the M group was 0%, and was significantly lower than that in the G group (40%) and the MMC group (40%) (P < 0.05). These results demonstrated that it is important not only to increase the granulocyte counts, but also to improve granulocyte functions for preventing infection under myelosuppression after chemotherapy.

Macrophage colony-stimulating factor restored chemotherapy-induced granulocyte dysfunctions: role of IL-8 production by monocytes

We evaluated the influence of M-CSF treatment on granulocyte functions in patients with ovarian cancer. Eighteen patients with ovarian cancer received two consecutive courses of chemotherapy (16 cases, CAP therapy and two cases, CP therapy) at 4-week intervals. M-CSF (8 million U/day) was infused for 7 days starting from the next day after chemotherapy. Superoxide anion production by isolated peripheral blood granulocytes, their phagocytosis, and expression of cell adhesion molecules such as CD11a, CD11b, and CD18 on granulocytes were measured by flow cytometry. Cytokine (IL-8, G-CSF, and GM-CSF) levels in peripheral blood monocyte (PBM) culture supernatants were measured by enzyme-linked immunosorbent assay in 5 out of 18 cases. The levels of CD11a, CD11b and CD18 expression on peripheral blood granulocytes and superoxide anion production by granulocytes were significantly suppressed by chemotherapy without CSF support. The levels of CD11a and CD18 expression on granulocytes were significantly enhanced by administration of M-CSF. When M-CSF was added to cultured PBM, the level of IL-8 in the supernatant increased with the concentration of M-CSF. When IL-8 was added to cultured granulocytes, the levels of CD18 expression on granulocytes and superoxide anion production by granulocytes were significantly increased. These observations suggest that M-CSF enhances the production of IL-8 from monocytes in vivo, thereby improving chemotherapy-induced granulocyte dysfunction.

Macrophage colony-stimulating factor prevents febrile neutropenia induced by chemotherapy

There are very few studies describing the preventive effect of macrophage colony-stimulating factor (M-CSF/CSF-1) on chemotherapy-induced infection. In this study, we evaluated the changes in superoxide anion production by granulocytes before and after chemotherapy in ovarian cancer patients and investigated the preventive effect of M-CSF on chemotherapy-induced febrile neutropenia. Three courses of chemotherapy [paclitaxel 180 mg/m(2) and carboplatin (area under the curve; AUC 5)] were administered to 32 ovarian cancer patients, and seven patients presented febrile neutropenia. In the 25 afebrile patients, the percentage of superoxide anion production by granulocytes was significantly decreased from 86.5 +/- 7.7 (%) to 75.1 +/- 8.8 (%) at day 7 and 71.0 +/- 6.3 (%) at day 14 without administration of CSF. However, in the patients who presented febrile neutropenia, it was more severely decreased from 86.8 +/- 6.8 (%) to 60.0 +/- 9.9 (%) at day 7 and 56.8 +/- 5.0 (%) at day 14 without administration of CSF. When M-CSF was administered to all patients in the next course with the same dose of chemotherapy, the incidence of febrile neutropenia was significantly decreased (P = 0.0195), and the duration of fever (>or= 38.0 degrees C) and high serum C-reactive protein (CRP) (>or= 2.0 mg/dl) were also significantly shortened (P = 0.0023, P = 0.0051). Moreover, in these M-CSF-treated patients, the percentage of superoxide anion production by granulocytes was maintained at the level before chemotherapy. These findings indicate that severe impairment of granulocyte function leads to febrile neutropenia, and that M-CSF reduces the incidence of febrile neutropenia by maintaining or improving granulocyte function.

Granulocyte colony-stimulating factor induces neutrophil sequestration in rabbit lungs

The effects of intravenous injection of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on circulating neutrophil numbers, pulmonary vascular permeability, and morphologic changes in the lung were examined in rabbits. Intravenous injection of rhG-CSF caused a rapid, profound neutropenia due to neutrophil sequestration primarily within capillaries but also in larger microvessels of the lungs. Examination of neutrophil deformability using microfilters revealed that granulocyte colony-stimulating factor (G-CSF) treatment caused a rapid stiffening of neutrophils through the polymerization of F-actin but not microtubule assembly. The expression of CD11b, CD11c, and CD18 on human neutrophils after G-CSF treatment increased, but CD11a did not. Intravenous injection of rhG-CSF did not induce neutrophil emigration or albumin leakage into alveolar space, wet/dry lung weight ratios were unchanged, and no pathologic changes in lung histology were observed. These studies indicate that injection of rhG-CSF caused a rapid neutropenia and neutrophil sequestration in the lungs that is likely to be mediated through a G-CSF-induced decrease in neutrophil deformability, although neutrophil-endothelial cell adhesion may also play a role. However, this G-CSF-induced neutrophil sequestration did not induce a massive lung injury.

Flow cytometric measurement of neutrophil alkaline phosphatase before and during initiation of an induced Escherichia coli mastitis in cattle

In 12 healthy cows, neutrophil alkaline phosphatase (NAP) activity was measured by flow cytometer before and during an experimentally induced Escherichia coli mastitis, to study the role and increase of NAP in Gram-negative bacterial infections. Percentage of neutrophils containing alkaline phosphatase and intensity of NAP activity were measured. Preinfection percentage of neutrophils with enzyme activity varied between 64.0% and 84.4% and the intensity of enzyme activity was low in all cows. After induction of infection, percentage of neutrophils with enzyme activity showed a significant decrease on day 1 followed by an significant increase on day 3. NAP intensity increased significantly on the second and third day after infection. This increase of intensity was significantly, positively correlated with the severity of infection. From this study we may conclude that variation in susceptibility to E. coli mastitis could not be explained by preinfection NAP levels. The post-infection increase of NAP activity, that was found following an induced infection was more a result of increased enzyme intensity per neutrophil, then from an increase of percentage neutrophils with enzyme activity. Furthermore, a strong correlation was found between NAP intensity and severity of inflammation. There was evidence that the more severely diseased animals showed stronger NAP intensity increase.

Adrenaline-induced leucocytosis: recruitment of blood cells from rat spleen, bone marrow and lymphatics

It is well known that adrenaline causes leucocytosis, but the sources and the mechanisms of this have not been clarified. We investigated the contributions of subpopulations of white blood cells to this leucocytosis and the importance of the spleen, bone marrow and lymphatics in releasing leucocytes into the blood stream following an injection of adrenaline. We studied possible effects of adrenaline on blood flow to the spleen and bone marrow to see if any contribution to leucocytosis from these organs could be perfusion dependent. In intact awake rats, total blood leucocytes increased within 5 min to about 220% of baseline concentration, the increases of lymphocytes and neutrophilic granulocytes being about 250% and 160%, respectively. The T and B lymphocytes and natural killer cells were all mobilized, to about 230% to 250% of baseline concentrations. The leucocytosis was short-lasting, so that the cell concentrations returned to baseline within 25 min after adrenaline injection. The bone marrow, spleen, and efferent lymphatics all contributed substantially to this leucocytosis, since band-nucleated granulocytes increased upon adrenaline injection, and splenectomized or thoracic duct drained rats showed a markedly reduced leucocytosis in response to adrenaline. Supplementary data were obtained with bone marrow depleted (with 89Sr irradiation) rats. The release of leucocytes from these organs was apparently not blood-flow dependent in the control rats since organ perfusion remained unaltered after adrenaline injection. Adrenaline was found to stimulate the release of both mono- and polymorphonuclear cells in the awake rat and the release of leucocytes from the spleen, bone marrow and efferent lymphatics to contribute significantly to the leucocytosis.