PPI’s aka protein pump inhibitors have been a true God-send for millions of patients with upper gastrointestinal problems: from reflux to gastritis to ulcers.  In large part they have supplanted the previously developed H-2 blockers:  Zantac, Axid, Pepcid and Tagamet. 

Both groups of medicines work by reducing production of the stomach acid, hydrochloric acid.  The chemical formula for this acid is HCI because it is made up of a hydrogen ion (also known as a proton) and a chloride ion.

Now, based on research at Harvard University, PPI’s may have a novel role in treating allergy.  It has been known for quite some time that PPI’s are very helpful in treating a severe form of esophagitis caused by allergy known as eosinophilic esophagitis (EOE).  Until the Harvard studies the reigning theory for the PPI’s benefit was that they controlled excess acid from further injuring the already allergy-inflamed esophagus.  And though this pathophysiology is probably still part of the benefit of the PPI’s it turns out they also exert an effect on the allergic MAST cells.

MAST cells cause allergic inflammation by releasing their cellular contents (contained in granules) including proteases, cytokines, and histamine.  As it turns out PPI’s block some non-gastric proton pumps including the one found inside MAST cells.  Blocking this intracellular proton pump changes the internal pH (acidity) of the MAST cells which interferes with their release of inflammatory molecules.  However, not all PPI’s exert this effect.  To date the only two known to do so are omeprazole and esomeprazole. 

The Harvard researchers hope to extend these findings to find even better ways to “deflate” the MAST cells and their inflammatory granules.