Fragments of e-Cadherin as Biomarkers of Non-erosive Reflux Disease

Abstract

Background: Approximately, 20% of patients with heartburn and normal endoscopic findings do not symptomatically improve on proton pump inhibitor (PPI) therapy making diagnosis and treatment uncertain. A biomarker distinguishing PPI-responsive from PPI-refractory heartburn is desirable.

Aims: We performed a pilot study assessing whether carboxy(C)-terminal fragments (CTFs) of e-cadherin in esophageal biopsies or amino(N)-terminal fragments (NTFs) of e-cadherin in serum could serve this purpose.

Methods: Twenty-nine patients with endoscopy-negative heartburn had esophageal biopsies for CTFs on Western blot and blood for serum NTFs on ELISA. All patients received dexlansoprazole 30 mg daily for 4 weeks, and heartburn was assessed by daily diary entry. Post-treatment blood samples were obtained for serum NTFs. A control group without GERD symptoms (n = 6) had biopsies for CTFs and a second control group (n = 20) blood serum for serum NTFs.

Results: Twenty-seven of 29 patients (93.1%) with endoscopy-negative heartburn, but 0 of 6 controls, were positive for CTFs. All patients and controls had measureable serum NTFs, but mean NTFs were significantly higher in those with PPI-responsive heartburn compared to those with PPI-refractory heartburn and controls. Following treatment, 24 of 29 (82.8) patients had relief of heartburn, which associated with a decline in mean NTFs compared to controls. NTFs in PPI-refractory patients (n = 5) were similar to controls before and after PPI therapy.

Conclusions: When heartburn responds to PPI, elevated serum NTFs decline to normal. These data suggest that cleaved products of e-cadherin may serve as biomarkers of NERD. Further data are needed to assess and confirm this concept.

Keywords: Dysphagia; Functional heartburn; Gastroesophageal reflux disease; Heartburn; Odynophagia.

Figure 1

An illustration of Western blots using a C-terminal antibody to e-cadherin on endoscopic esophageal biopsies for a group of 8 patients with non-erosive reflux disease (NERD) and that from 2 healthy control subjects. Note that all subjects have a band for intact e-cadherin at 120 kD while only those with NERD have one or more smaller bands (C-terminal fragments, CTFs). One prominent CTF in those with NERD is noted to migrate at 35 kD and another at 30 kD - see arrows. Only 2 of 6 controls are shown for illustrative purposes. [Note: The band for non-erosive reflux disease patients rides above the 100 kD marker and hence is a 120 kD band for intact e-cadherin; the 35 kD band for NERD patients resides immediately below the 37 kD levels and is thus consistent with a 35 kD band.]

Figure 2

A plot of the serum levels of N-terminal fragments (NTFs) of e-cadherin by ELISA using an N-terminal antibody in patients with non-erosive reflux disease (NERD) that are (A) completely, (B) partially, or (C) non-responsive to 4 weeks of treatment with dexlansoprazole 30 mg once per day. Serum from a group of healthy adult subjects served as a control. Values for NTFs are in absorbance. Note that prior to treatment NTFs for complete and partial responders are significantly higher than controls while for non-responders NTFs are similar to controls. Note also that after treatment the elevated NTF values for complete and partial responders decline to values that are no different than controls. Values are the mean ± SE, * p < 0.05 pre-treatment NERD values versus controls; # p < 0.05 post-treatment NERD values versus pre-treatment NERD values.

Figure 2

A plot of the serum levels of N-terminal fragments (NTFs) of e-cadherin by ELISA using an N-terminal antibody in patients with non-erosive reflux disease (NERD) that are (A) completely, (B) partially, or (C) non-responsive to 4 weeks of treatment with dexlansoprazole 30 mg once per day. Serum from a group of healthy adult subjects served as a control. Values for NTFs are in absorbance. Note that prior to treatment NTFs for complete and partial responders are significantly higher than controls while for non-responders NTFs are similar to controls. Note also that after treatment the elevated NTF values for complete and partial responders decline to values that are no different than controls. Values are the mean ± SE, * p < 0.05 pre-treatment NERD values versus controls; # p < 0.05 post-treatment NERD values versus pre-treatment NERD values.

Figure 3

A plot of the serum levels of N-terminal fragments (NTFs) of e-cadherin by ELISA using an N-terminal antibody in patients with non-erosive reflux disease (NERD) that combines both complete and partial responders to treatment for 4 weeks with dexlansoprazole 30 mg once per day. Serum from a group of healthy adult subjects served as a control. Values for NTFs are in absorbance. Note that before treatment the NTFs for this combined group of responders were significantly higher than controls and that after treatment these elevated values of NTFs decline, so that they are no longer significantly different than controls. Values are the mean ± SE, * p < 0.05 NERD versus controls.

Figure 4

A plot of the pre- and post-treatment serum levels of N-terminal fragments (NTFs) of e-cadherin by ELISA using an N-terminal antibody in patients with non-erosive reflux disease (NERD). The lines connect the pairs of values for individual patients that either completely or partially responded to treatment with 4 weeks of dexlansoprazole 30 mg once per day. Values for NTFs are in absorbance.