Expression of peroxisome proliferators-activated receptor-gamma and cyclooxygenase-2 in Helicobacter pylori infection-associated diseases and significance thereof

Abstract

To investigate the expression of peroxisome proliferators-activated receptor-gamma (PPAR-gamma) and cyclooxygenase-2 (COX-2) in Helicobacter pylori (Hp)-associated gastric mucosal lesions and the relations among them. Two-step immunohistochemical staining was used to detect the expression of PPAR-gamma and COX-2 proteins in the gastric biopsy specimens from 209 patients with lesions of gastric mucosa, including 75 cases of chronic superficial gastritis (CSG), 24 cases of chronic atrophic gastritis (CAG), and 90 cases of intestinal metaplasia (MI) and dysplasia (DYS), and from 20 subjects with normal gastric mucosa negative in Hp as controls. In addition, 36 CSG patients were followed up for 10 years to observe the changes of expression of PPAR-gamma and COX-2. (1) The expression of COX-2 protein in the glandular cells of the CSG, CAG, and IM + DYS groups were 42.7%, 45.8%, and 61.1% respectively, all significantly higher than that of the control group (20%, P < 0.01 or 0.05). The expression of COX-2 protein in the inflammatory cells of the CSG, CAG, and IM + DYS groups were 32%, 29.2%, and 36.7% respectively, all significantly higher than that of the control group (0%, all P < 0.05). (2) In the CSG and IM + DYS groups the expression levels of COX-2 in both the inflammatory and glandular cells were both significantly higher in the Hp-positive patients than in the Hp-negative patients (P < 0.05 or 0.01). (3) The expression of PPAR-gamma protein in the glandular cells of the CSG, CAG, and IM + DYS groups were 18.7%, 29.2%, and 45.6% respectively, all significantly higher than that of the control group (0%, all P < 0.01); and the expression levels of PPAR-gamma protein in the inflammatory cells of the CSG, CAG, and IM + DYS groups were 22.5%, 20.8%, and 22.2% respectively, all significantly higher than that of the control group (0%, P < 0.05 or 0.01). (4) In the CSG and IM + DYS groups the expression levels of PPAR-gamma in the inflammatory cells of the Hp-positive patients were both significantly higher than those of the Hp-negative patients (both P < 0.01); and the. expression levels of PPAR-gamma in the glandular cells of the Hp-positive patients were both significantly higher than those of the Hp-negative patients (both P < 0.01). (5) The expression level of COX-2 in the inflammatory cells of the CSG patients with a persistent Hp infection after a period of ten years was 33.3%, significantly lower than that a decade before (38.9%, P < 0.05). However, the expression level of PPAR-gamma in the inflammatory cells of the patients with a persistent Hp infection after a period of ten years was 30.6%, not significantly different from that a decade before (33.3%, P > 0.05). (6) The expression levels of COX-2 and PPAR-gamma in the glandular cells of the CSG patients with a persistent Hp infection after a period of ten years were 55.6% and 30.6% respectively, both significantly higher than those a decade before (47.2% and 22.2%, both P < 0.01). (7) In all Hp-negative disease groups the expression level of COX-2 in the inflammatory cells was not significantly correlated with the expression level of PPAR-gamma in the inflammatory cells(r = 0.006 and 0.149, P > 0.05) In the Hp-negative disease groups, the expression level of COX-2 in the glandular cells was significantly positively correlated with the expression level of PPAR-gamma in the glandular cells in the IM + DYS group (r = 0.336, P < 0.05), however, not significantly correlated with the expression level of PPAR-gamma in the glandular cells in both CAG and CSG groups (r = 0.035 and 0.126, both P > 0.05). (8) In both the inflammatory cells and glandular cells the COX-2 expression was significantly positively correlated with the PAR-gamma expression in all disease groups with Hp positivity (r = 0.348 and 0.645, P < 0.05 or 0.01). (1) Hp infection induces the overexpression of COX-2 and PPAR-gamma in the inflammatory and glandular cells within gastric mucosa, thus participating in the pathogenesis of gastric cancer (2) The expression of COX-2 induces by Hp is related to acute inflammation caused by Hp infection. In the glandular cells, significant increase of COX-2 and PPAR-gamma expression implies that along with time the expression of COX-2 and PPAR-gamma may change in advance of the morphological changes of the gastric mucosa.