Equine Airway Mast Cells are Sensitive to Cell Death Induced by Lysosomotropic Agents.
Mast cells are known for their detrimental effects in various inflammatory conditions. Regimens that induce selective mast cell apoptosis may therefore be of therapeutic significance. Earlier studies have demonstrated that murine- and human-cultured mast cells are highly sensitive to apoptosis induced by the lysosomotropic agent LeuLeuOMe (LLME). However, the efficacy of lysosomotropic agents for inducing apoptosis of in vivo-derived airway mast cells and the impact on mast cells in other species have not been assessed. Here we addressed whether lysosomotropic agents can induce cell death of equine in vivo-derived mast cells. Bronchoalveolar lavage (BAL) fluids from horses were incubated with LLME at 15-100 μm for up to 48 h. The overall cell viability was unaffected by 15 μm LLME up to 48 h, whereas a relatively modest drop in total cell counts (~30%) was seen at the highest LLME dose used. In contrast to the relatively low effect on total cell counts, LLME efficiently and dose dependently reduced the number of mast cells in BAL fluids, with an almost complete depletion (96%) of mast cells after 24 h of incubation with 100 μm LLME. A significant but less dramatic reduction (up to ~45%) of lymphocytes was also seen, whereas macrophages and neutrophils were essentially resistant. The appearance of apoptotic bodies suggested a mechanism involving apoptosis rather than necrosis. These findings suggest that equine airway mast cells are highly sensitive to lysosomotropic agents. Possibly, lysosomotropic agents could be of therapeutic value to treat disorders involving harmful accumulation of mast cells in the airways.
Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden.
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S
Wernersson
Department of Clinical Sciences, Section of Large Animal Surgery and Medicine, Equine Internal Medicine, Swedish University of Agricultural Sciences, Uppsala, Sweden.
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M
Riihimäki
Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden.|Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
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G
Pejler
Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden.
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I
Waern
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D002470:Cell Survival; D002478:Cells, Cultured; D004151:Dipeptides / Q000494:pharmacology* / Q000627:therapeutic use; D006734:Horse Diseases / Q000188:drug therapy; D006736:Horses; D006801:Humans; D006967:Hypersensitivity / Q000188:drug therapy*; D008214:Lymphocytes / Q000276:immunology; D008247:Lysosomes / Q000187:drug effects*; D008407:Mast Cells / Q000187:drug effects*; D051379:Mice; D012140:Respiratory Tract Diseases / Q000188:drug therapy / Q000662:veterinary
D004151:Dipeptides; C045139:leucyl-leucine-methyl ester