Increased expression of IL-10 and IL-12 (p40) mRNA in Helicobacter pylori infected gastric mucosa: relation to bacterial cag status and peptic ulceration

Aims-To investigate interleukin (IL)-12 (p40) and IL-10 mRNA expression lev els in the gastric mucosa in relation to H pylori cag status, peptic ulcera tion, and histopathology. Methods-In 81 dyspeptic patients, antral and corpus biopsies were taken for reverse transcriptase polymerase chain reaction (RT-PCR) and histology. G3 PDH (control) and IL-10 and IL-12 were coamplified in a duplex PCR and the ratios of cytokines to G3PDH were determined. Bacterial ureA and cagA statu s was determined by RT-PCR. Results-IL-10 mRNA expression in both the antral and corpus mucosa was grea ter (p < 0.01) in cagA positive infection than in H pylori negative patient s with histologically normal mucosa. No increase in IL-10 mRNA expression w as observed in cagA negative infection. Both in the antral and corpus mucos a, IL-12 mRNA expression was greater (p < 0.05) in cagA positive than in ca gA negative infection and uninfected patients with normal gastric mucosa. I n cagA positive infection, there was a correlation between IL-10 and IL-12 mRNA expression in both the antral mucosa (r = 0.515, p < 0.01) and the cor pus mucosa (r = 0.6, p < 0.005). IL-12 mRNA expression in the antral mucosa was significantly more frequent in H pylori positive patients with duodena l ulcer than in those with gastric ulcer or nonulcer dyspepsia. No differen ce was observed in IL-10 mRNA expression in relation to endoscopic diagnosi s. Conclusions-CagA positive H pylori infection is associated with increased I L-10 and IL-12 mRNA expression. The increased expression of IL-12 mRNA in t he majority of patients with duodenal ulcer suggests that Th1 responses may predominate and play a role in the pathogenesis of duodenal ulceration.