Interleukin-4 rapidly inhibits calcium transients in response to carbachol in bovine airway smooth muscle cells.
To assess interleukin (IL)-4 effects on calcium signaling, bovine airway smooth-muscle (ASM) cells were loaded with fura-2 and cytosolic calcium ([Ca(2+)](i)) was measured in single cells by digital microscopy. Human recombinant IL-4 (50 ng/ml) caused small increases in [Ca(2+)](i). For single cells, carbachol-stimulated calcium transients were compared before (S1) and after (S2) exposure to IL-4 or IL-13. When cells were treated with IL-4 (50 ng/ml) for 20 min, the S2/S1 ratio was 0.17 +/- 0.04 (n = 7) even though IL-4 had been washed from the chamber for 10 min before the S2 response. In contrast, controls not treated with IL-4 had S2/S1 of 0.70 +/- 0.04 (n = 13, P < 0.01). Lower concentrations of IL-4 variably decreased transients and IL-13 had no effect. In other experiments, 5 min of IL-4 did not immediately decrease transients but did after a 25-min delay. Goat antihuman IL-4 antibody abolished the effect of IL-4. IL-4 (50 ng/ml) also inhibited responses to caffeine (S2/S1: 0.30 +/- 0.04 and 0.54 +/- 0.06 for IL-4-treated versus control). We conclude that IL-4 rapidly inhibited calcium transients. Because caffeine-stimulated transients were inhibited, IL-4 may act, at least in part, by depleting calcium stores. IL-4 inhibition of cholinergic signaling may be important for modulating ASM responses during inflammation.
Madison
J M
JM
Division of Pulmonary, Allergy and Critical Care Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA. MadisonM@ummhc.org
Ethier
M F
MF
D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects*; D002217:Carbachol / Q000494:pharmacology*; D002417:Cattle; D005456:Fluorescent Dyes; D016257:Fura-2; D006801:Humans; D066298:In Vitro Techniques; D015847:Interleukin-4 / Q000494:pharmacology*; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D014132:Trachea / Q000187:drug effects* / Q000378:metabolism*
D005456:Fluorescent Dyes; D011994:Recombinant Proteins; D015847:Interleukin-4; D002110:Caffeine; D002217:Carbachol; D016257:Fura-2