Helicobacter Pylori is a gram-negative bacterium. It produces urease, has a spiral like conformation, microaerophilic and motile because of the flagella. H.pylori has developed mechanisms to survive the stomach environment and achieve persistent colonization. It is an active stimulator of both the innate and acquired immune responses. The hallmark of H.pylori infection is a marked inflammatory response with the infiltration of various immune cells into the infected gastric mucosa; the host immune response is unable to clear the infection and may actually contribute to the associated pathogenesis. In this context, recent interest has been focused on the role of CD74 the class II major histocompatibility complex -associated invariant chain expressed on the surface of gastric epithelial cells, as an adhesion molecules used by H.pylori that may contribute to the proinflammatory immune response seen during infection. Therefore, this study aimed to investigate the role of cytokines as well as CD74 expressed on gastric epithelial cells in the immunopathogenic association with H.pylori gastritis, in addition the attempt to use a 23S rRNA Real-Time PCR assay in combination with melting curve analysis, for the accurate detection of H. pylori infection, in Formalin fixed Paraffin-Embedded gastric biopsy samples. A total of 64 patients (41females and 23 males), aged between 14 and 66 years (mean age of 34 years), were screened for this study. Patients attended the Gastroenterology Unit at AL-Kadhimyia teaching hospital in Baghdad from 1st April to1st October 2007, because of recurrent abdominal pain and other gastrointestinal complaints. Three biopsies were obtained from grossly inflamed areas of the antrum. One biopsy was used for Ultra Rapid Urease test (URUT) and slide impression smear, while the other biopsy specimens were fixed with 10% buffered formalinized saline, for the preparation the paraffin embedded tissue blocks to histological evaluation, molecular diagnostic methods and Immunohistochemical staining tests (IHC). Also, blood sample was collected from each patient after the endoscopy for assays of IgG antibodies for H.pylori; serum gastrin-17 and to detect (serum interleukin-6 and interferon-gamma). A number of invasive URUT Test and slide impression smear) and non-invasive (anti-H. pylori IgG ELISA Test) diagnostic tests, as well as molecular diagnostic tests were used for the diagnosis of H. pylori infection; and a significant difference was noticed (P < 0.005) between positive and negative H.pylori infected patients by the above used tests. Accordingly, Patients were grouped as H. pylori positive group: n= 47 (73.4%) and H. pylori negative group: n=17 (26.5%). H. pylori infection found present in all age groups (p>0.05), and the anti-H.pylori IgG antibody titre was significantly associated (p<0.005) with mean age group of 39 years. There was no significant difference (p>0.05) between sex groups, and 57.9% of the H.pylori infected patients had Dyspepsia as common symptoms.
In the current study, the histological study was done to assess the histopathological changes in H.pylori associated gastritis. Chronic active gastritis was observed in all H. pylori-positive subjects, as well as, a large number of inflammatory infiltrated lymphocytes and neutrophils that seem to play an important role in the pathogenesis of the gastric injury of persons infected with H pylori. The grading of H. pylori related gastritis was high using the updated Sydney system for assessment of the degree of inflammatory activity, accordingly a significant difference was noticed (P < 0.005) between positive and negative H.pylori infected patients in chronic inflammation, atrophic gastritis, and in addition to surface epithelial damages. Moreover, in this study the level of serum gastrin-17 (S-G-17) was measured by Enzyme linked Immunosorbent Assay (ELISA) test, for detection the severity of Atrophic Gastritis in H.pylori infected patients. Accordingly, only eight patient serum samples had S-G-17 values < 2.5 pmol/l that indicates moderate or severe atrophic gastritis of the antrum area, interestingly, those eight patients serum samples were the only samples had a detectable serum IFN-γ by Enzyme Amplified Sensitivity Immunoassay (EASIA) test; while serum IL-6 was not detected in any serum samples. According to Immunohistochemical study of biopsy specimens an overexpression of CD74 observed in infected subjects.There was a significant difference (p= 0.005) in the expression of CD74 in association with increase local presence of IFN-γ and IL-6, as well as PMNCs and MNCs, in the gastric mucosa between infected and uninfected biopsy specimens.Interestingly, the Nested Real Time PCR described in this study was detected in gastric biopsies of the most common point mutations occurring in the 23S rRNA gene of H. pylori that confer resistance to clarithromycin among wild-type strains as analyzed by melting peak analysis; also indicated some samples contained mixed type of infection, which considered important information needed in treatment.