Thoracic and lumbar vertebroplasties performed in US Medicare enrollees, 2001-2005.

finding that DPP4 enzymatic activity in nasal tissue biopsies taken from patients with chronic rhinosinusitis was inversely correlated with the density of inflammatory cells in the nasal mucosa, and the DPP4 activity increased when chronic sinusitis was treated. Dipeptidyl peptidase 4 inactivates the proinflammatory peptide substance P that is released by sensory nerve fibers of the nasal mucosa during neurogenic inflammation. In pigs, the administration of recombinant DPP4 considerably attenuated the proinflammatory effect of histamine and capsaicin that causes the release of substance P, as well as the effect of substance P itself. Therefore, DPP4 should be considered as a modulator of the proinflammatory action of substance P. The review by Amori et al also found a higher incidence of headaches in patients treated with gliptins but did not note whether these patients were the same as those who developed nasopharyngitis. Headache is a major symptom in chronic sinusitis in association with mucosal congestion and decreased sinus drainage. Furthermore, substance P is hypothesized to have a key role in certain forms of headache. These data suggest that DPP4 may play a significant role in the development of inflammatory processes in the upper airway mucosa. Consequently, it would be important to evaluate potential disadvantages of DPP4 inhibitor use in patients with diabetes who have chronic sinusitis and headache.