Cell lines

Eosinophils

Preparation Method

Circulating eosinophils were purified from donors with eosinophils >35 per μL of blood. Eosinophil preparations with purity >98% and viability ~98% were used.

Reaction Conditions

Eosinophils were cultured at 1 × 106/mL in complete medium (RPMI 1640 plus 10% fetal bovine serum) with IL3 (2 ng/mL) or IL5 (2 ng/mL) both cytokines from BD Biosciences for 20 h, and were then washed and cultured with complete medium (no IL3 or IL5) on coated heat-aggregated immunoglobulins-G (HA-IgG or IgG) or without IgG as previously described.

Applications

Bafilomycin-A1 could be used to show the impact of autophagolysosome formation on eosinophil cytolysis. Treated IL3- and IL5-primed eosinophils with bafilomycin-A1 before interaction with IgG, and then measured cytolysis using rhodamine-110 (R110). Treatment with bafilomycin-A1 increased IL3-primed and IL5-primed eosinophil lysis by 50% and 100%, respectively, suggesting that autophagolysosome formation protects from cytolysis for both IL3- and IL5-primed eosinophils.

Animal models

Lck-mTOR + CLP mice, WT + CLP mice, Lck-TSC1 mice

Preparation Method

Crossed TSC1loxp/loxp and mTORloxp/loxp mice with Lck-Cre mice (Cre expression under the control of lymphocyte-specific protein tyrosine kinase, Lck) to obtain the F1 generation Lck-Cre:mTORloxp/– mice and Lck-Cre:TSC1loxp/– mice, respectively. We interbred F1 generation mice in each group and obtained F2 generation Lck-Cre: mTORloxp/loxp and Lck-Cre;TSC1loxp/loxp mice. Littermates lacking Lck-Cre served as controls. Then mice were anesthetized, and the abdomen was opened surgically and the cecum was ligated halfway between the distal pole and the base. The cecal stump was punctured once with a 22-gauge needle. Put back the cecum and closed the abdomen. Administered 1 mL saline subcutaneously to each animal for fluid resuscitation. Animals in the sham group underwent the same surgical procedure without ligation or puncture. Bafilomycin A1 was administered intraperitoneally 1 h after the CLP operation.

Dosage form

1 mg/kg

Applications

Bafilomycin A1 could specifically block fusion of autophagosomes and lysosomes and attenuate the protective effects of mTOR deletion against CD4 + T cell apoptosis. In Lck-mTOR + CLP mice treated with bafilomycin A1, the apoptosis rate of CD4 + T cells was higher compared with mice that did not receive bafilomycin A1 and lower compared with mice in WT + CLP + bafilomycin A1 group.

• Am J Transplant (2022):22(5)PMID: 35092164
• BioRxiv (2022).
• Int J Mol Sci 23.8 (2022): 4128.

Bafilomycin A1, a macrolide antibiotic isolated from the Streptomyces species, is an inhibitor of vacuolar H ATPase (V-ATPase). Bafilomycin A1 has been used to study the autophagy as an inhibitor of autophagosomes-lysosomes fusion and as an inhibitor of lysosomal degradation.[1] It binds to the V0 sector subunit c of the V-ATPase complex and inhibits H translocation which cause an accumulation of H in the cytoplasm of treated cells. Bafilomycin A1 inhibits cell growth and leads to apoptosis and differentiation. These anticancer effects of Bafilomycin A1 are considered to be attributable to the intracellular acidosis caused by V-ATPase inhibition.^[2]

In vitro study of Bafilomycin A1 indicated that Bafilomycin A1 preferentially inhibits in vitro growth of pediatric B-cell acute lymphoblastic leukemia cells. A various of leukemia cell lines including 697, Nalm-6, RS4;11, NB4, HL-60, K562 and BV173 representing B-ALL (697, Nalm-6, RS4;11), acute myeloid leukemia (NB4, HL-60), and chronic myeloid leukemia (K562, BV173) were used to investigate the effect of Bafilomycin A1. Cells were cultured in the presence of increasing concentrations of Bafilomycin A1 (0 nM, 0.5 nM, 1 nM). Cell proliferation was measured using an MTT assay. Results showed that Bafilomycin A1 has frequently been used as an inhibitor to block the autophagosomes-lysosomes fusion, or to inhibit lysosomal activity at high doses (0.1–1 mμ). While low concentration of Bafilomycin A1 (1 nM) cpuld effectively and specifically inactivate autophagy and activate apoptosis at multiple targets in pediatric B-ALL cells.^[3]

In vivo study demonstrated that Bafilomycin A1 can extend survival in the Bafilomycin A1-treated B-ALL mice with advanced disease compared with control mice. The red blood cell counts, hemoglobin concentration, and platelet counts in the B-ALL model group were extremely reduced, however they were normalized in the Bafilomycin A1-treated group. The mice in the B-ALL model group had severe hepatosplenomegaly compared with the control group. However, the size and weight of livers and spleens in the Bafilomycin A1-treated group were normalized compared with those in the disease model group. Results showed that Bafilomycin A1 dramatically inhibits pediatric B-ALL cell engraftment by targeting leukemia cells in vivo.^[3]

References:
[1]. Yamamoto A, et al. Bafilomycin A1 prevents maturation of autophagic vacuoles by inhibiting fusion between autophagosomes and lysosomes in rat hepatoma cell line, H-4-II-E cells. Cell Struct Funct. 1998;23(1):33–42.
[2] Bowman EJ, et al. The bafilomycin/concanamycin binding site in subunit c of the V-ATPases from Neurospora crassa and Saccharomyces cerevisiae. J Biol Chem. 2004;279(32):33131–33138.
[3]. Yuan N, et al. Bafilomycin A1 targets both autophagy and apoptosis pathways in pediatric B-cell acute lymphoblastic leukemia. Haematologica. 2015 Mar;100(3):345-56.