The inhibitory effects of H+ K+ ATPase inhibitors on human neutrophils in vitro: restoration by a K+ ionophore.
OBJECTIVE
This study investigated the ability of proton pump inhibitors (PPI), such as omeprazole and pantoprazole, to inhibit neutrophil migration, calcium mobilization and the mechanisms involved in this inhibition.


METHODS
Neutrophils were incubated with different concentrations of omeprazole and pantoprazole for 30 min and stimulated to migrate with fMLP and IL-8. Treatment toxicity was assessed by MTT assay. The intracellular calcium levels were analyzed in neutrophils pre-treated with omeprazole and pre-loaded with FURA-2AM, when stimulated with fMLP. The activity of p38 MAP Kinase was evaluated by Western blot after treatment with omeprazole.


RESULTS
Omeprazole is able to inhibit neutrophil chemotaxis to fMLP and IL-8. Pantoprazole demonstrated the same ability. This inhibitory effect was not due to a toxic effect of the proton pump inhibitors. Inhibition of v-ATPase by bafilomycin did not modify the ability of fMLP or IL-8 to induce neutrophil migration. Omeprazole was also able to decrease intracellular calcium availability. The addition of a potassium ionophore, nigericin, restored the migratory ability, as well as the intracellular calcium levels. The activity of p38 MAP Kinase was decreased in neutrophils pretreated with omeprazole.


CONCLUSIONS
Proton pump inhibitors promote inhibition of H+ K+ ATPase in neutrophils, resulting in cationic flow disturbances through the cellular membrane that, consequently, inhibit migratory and intracellular events such as calcium influx and p38 MAP Kinase activation.
Martins de Oliveira
R
R
Clinical Pharmacology and Gastroenterology Unit, São Francisco University Medical School, Av. São Francisco de Assis 218, 12916-900, Bragança Paulista, SP, Brazil.
Antunes
E
E
Pedrazzoli
J
J
Gambero
A
A
D053799:2-Pyridinylmethylsulfinylbenzimidazoles / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D005744:Gastric Acid / Q000378:metabolism; D017506:H(+)-K(+)-Exchanging ATPase / Q000378:metabolism; D006801:Humans; D016209:Interleukin-8 / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology*; D018942:Macrolides / Q000494:pharmacology; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology*; D009550:Nigericin / Q000494:pharmacology*; D009853:Omeprazole / Q000494:pharmacology; D000077402:Pantoprazole; D011188:Potassium / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D054328:Proton Pump Inhibitors; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D016209:Interleukin-8; D007476:Ionophores; D018942:Macrolides; D047428:Protein Kinase Inhibitors; D054328:Proton Pump Inhibitors; C057620:bafilomycin A; D009240:N-Formylmethionine Leucyl-Phenylalanine; D000077402:Pantoprazole; D048051:p38 Mitogen-Activated Protein Kinases; D017506:H(+)-K(+)-Exchanging ATPase; D009853:Omeprazole; D009550:Nigericin; D011188:Potassium; D002118:Calcium