Association between Increased Gastric Juice Acidity and Sliding Hiatal Hernia Development in Humans

<div><p>Objectives</p><p>Several clinical factors; overweight, male gender and increasing age, have been implicated as the etiology of hiatal hernia. Esophageal shortening due to acid perfusion in the lower esophagus has been suggested as the etiological mechanism. However, little is known about the correlation between gastric acidity and sliding hiatus hernia formation. This study examined whether increased gastric acid secretion is associated with an endoscopic diagnosis of hiatal hernia.</p><p>Methods</p><p>A total of 286 consecutive asymptomatic patients (64 were diagnosed as having a hiatal hernia) who underwent upper gastrointestinal endoscopy were studied. Clinical findings including fasting gastric juice pH as an indicator of acid secretion, age, sex, body mass index, and <i>Helicobacter pylori</i> infection status determined by both <i>Helicobacter pylori</i> serology and pepsinogen status, were evaluated to identify predictors in subjects with hiatal hernia.</p><p>Results</p><p>Male gender, obesity with a body mass index >25, and fasting gastric juice pH were significantly different between subjects with and without hiatal hernia. The cut-off point of fasting gastric juice pH determined by receiver operating curve analysis was 2.1. Multivariate regression analyses using these variables, and age, which is known to be associated with hiatal hernia, revealed that increased gastric acid secretion with fasting gastric juice pH <2.1 (OR = 2.60, 95% CI: 1.38–4.90) was independently associated with hiatal hernia. Moreover, previously reported risk factors including male gender (OR = 2.32, 95% CI: 1.23–4.35), body mass index >25 (OR = 3.49, 95% CI: 1.77–6.91) and age >65 years (OR = 1.86, 95% CI: 1.00–3.45), were also significantly associated with hiatal hernia.</p><p>Conclusions</p><p>This study suggests that increased gastric acid secretion independently induces the development of hiatal hernia in humans. These results are in accordance with the previously reported hypothesis that high gastric acid itself induces hiatal hernia development.</p></div

Characteristics of the study population (N = 286).

<p>Characteristics of the study population (N = 286).</p

Receiver operating characteristic (ROC) curve analysis using fasting gastric juice pH as a predictor of hiatal hernia.

<p>At a cut-off value of 2.1, gastric juice pH exhibited 49.1% sensitivity and 69.7% specificity for predicting hiatal hernia, and area under the curve (AUC) of 0.592 (95% CI 0.515–0.670, <i>p</i><0.05).</p

Flow diagram of study populations.

<p>Flow diagram of study populations.</p

Characteristics of the subjects with and without hiatal hernia and univariate analysis of risk factors for hiatal hernia.

<p>Characteristics of the subjects with and without hiatal hernia and univariate analysis of risk factors for hiatal hernia.</p

Multivariate analysis: Relationship of hiatal hernia with fasting gastric juice pH, sex, body mass index, <i>H</i>. <i>pylori</i> infection status and age.

<p>Multivariate analysis: Relationship of hiatal hernia with fasting gastric juice pH, sex, body mass index, <i>H</i>. <i>pylori</i> infection status and age.</p

NoV VLPs specifically bound and internalized into human small intestinal epithelium.

<p>Fresh human ileum biopsy specimens from a single individual (individual A) were incubated with 2.5 µg/ml of VLPs in PBS(-) for 1 h at 4°C, and washed three times with PBS(-). After fixation with periodate lysine paraformaldehyde, specimens were dehydrated stepwise in 10, 15, and 20% sucrose/PBS, and embedded in OCT compound. Cryostat sections at 6 µm were incubated with primary antibodies specific for VLPs and stained with the Alexa dye–conjugated secondary antibody and DAPI, and subjected to confocal laser-scanning microscopy. The results of experiment with rabbit anti-Ueno 7k VLP serum and the 5B18 mouse monoclonal antibody as primary antibody are depicted in the panels A and B, respectively. Panels b–d are high magnification views of the area in boxes in panel a. Green, NoV VLPs; blue, nuclei. Scale bars in panel a = 200 µm, and in panel d = 100 µm.</p

NoV VLPs were colocalized with each HBGA on the surface of epithelial and goblet cells.

<p>Fresh human ileum biopsy specimens from a single individual (individual B) were incubated with 2.5 µg/ml of NoV VLPs in PBS(-) for 1 h at 4°C and subjected to immunofluorescence microscopy. Cryostat sections were incubated with rabbit anti-Ueno 7k VLP serum and mouse anti-type H1, H2 or Le^b HBGA antibody and stained with Alexa dye–conjugated secondary antibodies and DAPI. Immunofluorescence images for type H1, H2 or Le^b HBGA are shown in panels A, B and C, respectively. Panels d–f and g–i are high magnification views of areas in boxes in panels a–c, respectively. Green, NoV VLPs; red, type H1 HBGA, type H2 HBGA or type Le^b HBGA. Scale bars in panel c = 100 µm, and in panel f and i = 20 µm.</p

NoV VLPs of 485 strain also bound and internalized to intestinal epithelium.

<p>Fresh human ileum biopsy specimens from a single individual (individual B) were incubated with 2.5 µg/ml of Ueno 7k VLPs or 485 VLPs in PBS(-) for 1 h at 4°C and subjected to immunofluorescence microscopy. Cryostat sections were incubated with rabbit anti-Ueno 7k VLP serum or rabbit anti-485 VLP serum, and stained with Alexa dye–conjugated secondary antibody. Immunofluorescence images for Ueno 7k VLPs and 485 VLPs were depicted in left and right panels, respectively. Green, NoV VLPs. Scale bar = 100 µm.</p

Binding of NoV VLPs to Caco-2 cells depended on the state of cell differentiation.

<p>Caco-2 cells were incubated with VLPs at 4°C and subjected to immunofluorescence microscopy (A). Areas of VLP binding on undifferentiated and differentiated Caco-2 cells were quantified with Adobe Photoshop software. Quantifications were performed with nine images, and Student's <i>t</i>-test was used for statistical comparisons. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066534#s3" target="_blank">Results</a> represent the means of ± S.D. of nine determinations (B). Caco-2 cells were lysed, and lysates were analyzed by SDS-PAGE/western blot with rabbit antibody against sucrase-isomaltase (SI), a differentiation marker for Caco-2 cells, with ß-actin as an internal control (ß-ACT) (C).</p