Maitake beta-glucan promotes recovery of leukocytes and myeloid cell function in peripheral blood from paclitaxel hematotoxicity

Abstract

Bone marrow myelotoxicity is a major limitation of chemotherapy. While granulocyte colony stimulating factor (G-CSF) treatment is effective, alternative approaches to support hematopoietic recovery are sought. We previously found that a beta-glucan extract from maitake mushroom Grifola frondosa (MBG) enhanced colony forming unit-granulocyte monocyte (CFU-GM) activity of mouse bone marrow and human hematopoietic progenitor cells (HPC), stimulated G-CSF production and spared HPC from doxorubicin toxicity in vitro. This investigation assessed the effects of MBG on leukocyte recovery and granulocyte/monocyte function in vivo after dose intensive paclitaxel (Ptx) in a normal mouse. After a cumulative dose of Ptx (90-120 mg/kg) given to B6D2F1mice, daily oral MBG (4 or 6 mg/kg), intravenous G-CSF (80 microg/kg) or Ptx alone were compared for effects on the dynamics of leukocyte recovery in blood, CFU-GM activity in bone marrow and spleen, and granulocyte/monocyte production of reactive oxygen species (ROS). Leukocyte counts declined less in Ptx + MBG mice compared to Ptx-alone (p = 0.024) or Ptx + G-CSF treatment (p = 0.031). Lymphocyte levels were higher after Ptx + MBG but not Ptx + G-CSF treatment compared to Ptx alone (p < 0.01). MBG increased CFU-GM activity in bone marrow and spleen (p < 0.001, p = 0.002) 2 days after Ptx. After two additional days (Ptx post-day 4), MBG restored granulocyte/monocyte ROS response to normal levels compared to Ptx-alone and increased ROS response compared to Ptx-alone or Ptx + G-CSF (p < 0.01, both). The studies indicate that oral MBG promoted maturation of HPC to become functionally active myeloid cells and enhanced peripheral blood leukocyte recovery after chemotoxic bone marrow injury.

Fig. 1

Paclitaxel induction of leukopenic mouse model: Ptx was given at cumulative doses of 60 and 90 mg/kg. Complete blood counts (CBCs) were compared to untreated mice (n = 4 each group) over 10 days. Comparison of mean absolute counts of leukocytes, neutrophils, and lymphocytes are shown. The arrows on the top in each chart indicate days of Ptx injection. Data are shown as group mean absolute counts ± SD

Fig. 2

MBG enhancement of CFU-GM activity after Ptx: 2 days after the last Ptx injection, bone marrow (BM) and spleen (SP) cells were collected for ex vivo colony forming unit assays (CFU). (a) Ptx + MBG 4 mg/(kg day) treated mice had significantly higher CFU-GM counts in BM and SP (p < 0.001, p = 0.002, respectively) compared to Ptx alone by ANOVA. (b) Ptx + MBG 6 mg/(kg day) led to increased CFU-GM in BM (p = 0.003), and showed a trend towards increase in SP

Fig. 3

Effect of MBG on leukocyte recovery after Ptx: (a) the decrease in white blood cell (WBC) count was less in the Ptx + MBG group compared to Ptx-alone (p = 0.024), or after Ptx + G-CSF (p = 0.031). (b) At 2 days post-Ptx, the decline WBC in the Ptx + MBG group was less compared to Ptx-alone (p < 0.05), or G-CSF (p < 0.01) since the effect of G-CSF was not evident 24 h after injection. (c) On day 8 post-Ptx, both Ptx + MBG and Ptx + G-CSF groups had similar mean WBC counts that were higher compared to Ptx-alone (p < 0.001)

Fig. 4

Effect of MBG on neutrophil recovery after Ptx: (a) Ptx decreased neutrophil counts in all groups that lasted until post-Ptx day 5 for the Ptx + MBG and Ptx + G-CSF groups. (b) On post-Ptx day 5, neutrophils were less decreased in the Ptx + MBG (p < 0.05) and Ptx + G-CSF (p < 0.01) groups compared to Ptx alone. (c) On day 8 post-Ptx, neutrophil counts had rebounded far above baseline after both Ptx + MBG and Ptx + G-CSF but not after Ptx-alone

Fig. 5

Effect of MBG on lymphocyte recovery after Ptx: Ptx reduced lymphocyte numbers in all groups compared to the baseline (p < 0.0001). By post-day 5, lymphocyte counts were higher than baseline for the Ptx + MBG (p < 0.01) but not the Ptx + G-CSF group. On post-day 8 counts were higher than baseline for both Ptx + MBG and Ptx + G-CSF groups (p < 0.01) but not for Ptx-alone

Fig. 6

MBG promoted early recovery of myeloid function: (a) Peripheral blood Gr-1+ granulocyte/monocyte production of reactive oxygen species (ROS) was tested ex vivo 4 days after Ptx by flow cytometry. Response to E. coli in the Ptx-alone and Ptx + G-CSF groups was lower compared to untreated mice (p < 0.01 for both). ROS response was higher in the Ptx + MBG group compared to Ptx alone (p < 0.01) or Ptx + G-CSF (p < 0.01), and equal to untreated mice. Response to fMLP stimulation was higher in the Ptx + MBG group than either untreated mice (p < 0.01) or the Ptx + G-CSF group (p < 0.05). (b) At post-Ptx day 11 ROS response to E. coli was now equal in all treated groups and higher than in untreated mice (p < 0.0001). However, fMLP response in the Ptx + MBG group was higher compared to Ptx-alone or Ptx + G-CSF groups (p = 0.013 and p = 0.014, respectively)