Targeting ATP12A, a Nongastric Proton Pump α Subunit, for Idiopathic Pulmonary Fibrosis Treatment.

Idiopathic pulmonary fibrosis (IPF) is a pathological condition of unknown etiology that results from injury to the lung and an ensuing fibrotic response that leads to the thickening of the alveolar walls and obliteration of the alveolar space. The pathogenesis is not clear, and there are currently no effective therapies for IPF. Small airway disease and mucus accumulation are prominent features in IPF lungs, similar to cystic fibrosis lung disease. The ATP12A gene encodes the α-subunit of the nongastric H+, K+-ATPase, which functions to acidify the airway surface fluid and impairs mucociliary transport function in patients with cystic fibrosis. It is hypothesized that the ATP12A protein may play a role in the pathogenesis of IPF. The authors' studies demonstrate that ATP12A protein is overexpressed in distal small airways from the lungs of patients with IPF compared with normal human lungs. In addition, overexpression of the ATP12A protein in mouse lungs worsened bleomycin induced experimental pulmonary fibrosis. This was prevented by a potassium competitive proton pump blocker, vonoprazan. These data support the concept that the ATP12A protein plays an important role in the pathogenesis of lung fibrosis. Inhibition of the ATP12A protein has potential as a novel therapeutic strategy in IPF treatment.

Hydrogen-potassium ATPase inhibitors induce relaxation on rabbit prostatic strips in vitro.

BACKGROUND: To determine the relaxant effect of omeprazole and lansaprazole, hydrogen-potassium (H+-K+) ATPase inhibitors, on rabbit prostatic tissue in vitro. METHODS: Male New Zealand white rabbits were sacrificed and their prostatic tissues were removed. The prostatic stromal strips were mounted in organ baths and relaxation responses were obtained in precontracted tissues with phenylephrine, carbachol and potassium chloride (KCl). Relaxation responses were controlled in the presence of various antagonists to explain the mechanism for relaxation exerted by omeprazole and lansaprazole. RESULTS: Omeprazole and lansaprazole caused similar relaxation responses in the prostatic strips precontracted with phenylephrine, carbachol and KCl. The addition of prostaglandin synthase inhibitor indomethacin, nitric oxide synthase inhibitor L-NAME, potassium channel blockers, glibenclamide and tetraethylammonium into the organ baths did not change the relaxations induced by omeprazole and lansaprazole in vitro. CONCLUSION: Omeprazole and lansaprazole cause a relaxation in prostatic stromal tissue precontracted with phenyephrine, carbachol and KC1 in vitro. This relaxant effect is independent of H+-K+ ATPase inhibition. Additionally, cyclooxygenase and nitric oxide pathways do not contribute to this relaxant effect. Further studies are required to determine whether these drugs may have a beneficial effect in the non-operative treatment of benign prostatic hyperplasia.

Lansoprazole versus ranitidine for the treatment of reflux oesophagitis. UK Lansoprazole Clinical Research Group.

BACKGROUND: Lansoprazole is a H+.K(+)-ATPase (proton pump) inhibitor with an anti-secretory action and is therefore potentially useful in the treatment of gastro-oesophageal reflux. METHODS: This study was conducted to determine the efficacy and short-term safety of lansoprazole at doses of 30 mg or 60 mg once daily, compared with ranitidine 150 mg twice daily, in the treatment of patients with reflux oesophagitis. This was a double-blind, stratified, randomized, comparative, parallel group study conducted in five centres in the UK. A total of 229 patients (155 men) aged 18-79 years with endoscopically-confirmed oesophagitis were randomized to receive lansoprazole 30 mg p.o. daily, lansoprazole 60 mg p.o. daily, or ranitidine 150 mg p.o. b.d. Efficacy was assessed by endoscopic examination at 4 weeks and 8 weeks, together with symptom relief and antacid usage. RESULTS: Lansoprazole 30 mg and 60 mg were superior at 4 and 8 weeks (P < 0.01) to ranitidine in healing reflux oesophagitis: respective healing rates being 84%, 72% and 39% after 4 weeks and 92%, 91% and 53% after 8 weeks. Relief of heartburn with lansoprazole 30 mg and 60 mg was superior to that achieved with ranitidine at both week 4 (P < 0.01) and week 8 (P < 0.02). Sixty-four patients experienced a total of 85 adverse events, one-third of which were considered drug-related. The incidence and severity were similar in the three groups. CONCLUSION: Lansoprazole 30 mg and 60 mg once daily are more effective than ranitidine 150 mg twice daily in the short-term treatment of reflux oesophagitis.