Cooperative genotyping for Helicobacter pylori virulence determinants strengthens the predictive value of gastric cancer risk assessment

Digestive and Liver Disease 42 (2010) 662–664

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Correspondence Cooperative genotyping for Helicobacter pylori virulence determinants strengthens the predictive value of gastric cancer risk assessment Sir, Heterogeneous genetic profiles of Helicobacter pylori are considered as key components of host–pathogen-environment triad interaction and play crucial roles in the gastric carcinogenesis [1]. Persistent colonisation and maintenance of H. pylori in the harsh environment of the stomach are attributed to a series of virulence determinants. Two potent polymorphic secretory toxins; vacA and cagA and the functionally active adhesin babA2 are identified as the more decisive virulence markers in the development of the more severe disease outcomes [2–5]. This study was undertaken to determine how H. pylori virulence markers as screening determinants may comparatively predict the risk of gastric cancer (GC) independently or cooperatively. Collectively, 212 Iranian H. pylori infected patients including 48 GC and 164 non-GC patients were assessed for H. pylori vacA polymorphic alleles, cagA polymorphism and functional babA2 using PCR. The mean age ± standard deviation of GC patients (35 males and 13 females) was 58.89 ± 11.55 years whereas this value was 41.15 ± 14.85 (90 males and 73 females) for non-GC endoscopy patients. The impact of genotypes on GC risk was estimated in terms of odds ratios (ORs) with 95% confidence intervals (CIs) using a Backward Wald elimination of variables in multivariate logistic regression analysis, in which both factors of age and gender were included. This analysis revealed that each gene individually or cooperatively, was significantly associated with GC risk (Table 1). The OR for GC risk was further increased significantly with the num-

ber of studied genes as follows: ONE studied gene: for s1i1m1 vacA; OR = 4.8 [95%CI: 2.470–9.667], for babA2+; OR = 3.3 [95%CI: 1.42–8], for ABCC cagA; OR = 2.5 [95%CI:1.28–5.02], TWO studied genes: for s1i1m1/ABCC cagA; OR = 5.1 [95%CI: 2.13–12.49], for s1i1m1/babA2+; OR = 5.9 [95%CI: 2.98–12.01], and THREE studied genes: for s1i1m1/babA2+/ABCC cagA; OR = 6.3 [95%CI: 2.53–16.14]. As indicated in Table 1, the s1 or i1 vacA alleles individually affect the GC risk up to more than 8-fold, which was higher than that of concurrent carriage of s1i1m1/babA2+/ABCC cagA. However, the percentages of GC cases detected amongst dyspeptic patients harbouring the virulent genotype, increased with the number of studied genes and alleles (positive predictive value (PPV), Table 1). This analysis, thus, provides evidence of cooperative activity of H. pylori virulence genes in the development of gastric malignancy. Therefore, we propose the application of collective H. pylori virulence determinant genotyping in order to strengthen the power of population screening for the risk of GC in high prevalent geographic regions. These efforts should certainly take into consideration the cooperative predictive power of host–pathogen-environment susceptibility factors. Conflict of interest statement None declared. Acknowledgement This study was supported by a generous grant from the Deputy of Research and Technology of the Iranian Ministry of Health and Medical Education in support of international research collaboration.

Table 1 Association of H. pylori genotype(s) with gastric cancer. Genotype (positive vs. others)

Cases n (%)

Controls n (%)

P value

OR

95%CI

PPV %

NPV %

s1 vacA i1 vacA m1 vacA babA2 ABCC cagA s1i1m1 vacA s1i1m1/ABCC cagA s1i1m1/babA2+ s1i1m1/babA2+/ABCC cagA

46 (95.8) 42 (87.5) 29 (60.4) 41 (85.4) 20 (41.7) 29 (60.4) 13 (27.1) 27 (56.3) 13 (27.1)

119 (72.6) 75 (45.7) 42 (25.6) 104 (63.4) 36 (22) 39 (23.8) 11 (6.7) 29 (17.7) 9 (5.5)

0.004 0.001 0.001 0.006 0.007 0.001 0.001 0.001 0.001

8.697 8.307 4.434 3.379 2.540 4.892 5.166 5.985 6.397

2.027–37.326 3.347–20.614 2.254–8.720 1.427–8.003 1.283–5.026 2.470–9.667 2.137–12.492 2.980–12.019 2.535–16.143

27.9 35.9 40.8 28.3 35.7 42.6 54.2 48.2 59.1

95.7 93.6 86.5 89.5 82 86.8 81.3 86.5 81.5

OR: odds ratio; CI: confidence interval; PPV: positive predictive value; and NPV: negative predictive value. Bolded numbers represent statistically significant values (P < 0.05).

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Correspondence / Digestive and Liver Disease 42 (2010) 662–664

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References [1] Amieva MR, El-Omar EM. Host–bacterial interactions in Helicobacter pylori infection. Gastroenterology 2008;134:306–23. [2] Naito M, Yamazaki T, Tsutsumi R, et al. Influence of EPIYA-repeat polymorphism on the phosphorylation-dependent biological activity of Helicobacter pylori CagA. Gastroenterology 2006;130:1181–90. [3] Rhead JL, Letley DP, Mohammadi M, et al. A new Helicobacter pylori vacuolating cytotoxin determinant, the intermediate region, is associated with gastric cancer. Gastroenterology 2007;133:926–36. [4] Sugimoto M, Zali MR, Yamaoka Y. The association of vacA genotypes and Helicobacter pylori-related gastroduodenal diseases in the Middle East. Eur J Clin Microbiol Infect Dis 2009;28(10):1227–36. [5] Zambon CF, Navaglia F, Basso D, et al. Helicobacter pylori babA2, cagA, and s1 vacA genes work synergistically in causing intestinal metaplasia. J Clin Pathol 2003;56:287–91.

Masoumeh Douraghi a,b Yeganeh Talebkhan a Hojjat Zeraati c Marjan Mohammadi a,∗ a Helicobacter pylori Research Group, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran b Department of Bacteriology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran c Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran ∗

Corresponding author at: Biotechnology Research Center, Pasteur Institute of Iran, Tehran 13164, Iran. Tel.: +98 2166480780; fax: +98 2166480780. E-mail address:[email protected] (M. Mohammadi) Available online 20 February 2010

doi:10.1016/j.dld.2010.01.010

Diagnosis of jejunal diverticulosis by means of double balloon enteroscopy Dear Sir, Jejunal diverticula (JD) are rare entities, revealed in less than 5% of post-mortem examinations [1]. JD are usually multiple and are determined by the herniation of the mucosa and submucosa through the muscular layer at the mesenteric border as a consequence of a disturbed motor function. JD are generally asymptomatic and thus diagnosed incidentally at laparotomy, but in some cases may determine symptoms, such as abdominal pain and bloating, and complications, mainly perforation, haemorrhage, obstruction, and diverticulitis [2]. Diagnosis of JD is difficult due to difficulties in studying the small intestine, but the recent development of new endoscopic (capsule endoscopy and device-assisted enteroscopy-DAE) and radiologic (CT- and MR-enteroclysis) methods has increased the number of JD reports. We herein report a case of a 70-year-old woman presented with a clinical picture of partial intestinal obstruction. In the past she had suffered from bloating, fullness, and abdominal pain and had complained two episodes of partial intestinal obstruction. She had been investigated by means of abdominal ultrasound, upper endoscopy, colonoscopy and glucose breath test revealing only bacterial overgrowth. During the last hospitalization a bowel ultrasound showed a marked dilatation (up to 4 cm) of jejunal loops, without mass or significant thickening of bowel walls. Small bowel follow through was not possible due to failed jejunal intubation and CT-enteroclysis demonstrated again dilation, but was unable to show stenosis at any level of the GI tract (Fig. 1C). Due to the inconclusive results of both US and CT, double balloon enteroscopy was performed.

Fig. 1. Several diverticula of different sizes in the proximal jejunum (A); some diverticula have a very large lumen (B). CT-enteroclysis demonstrates a marked dilatation of jejunal loops, without mass or significant thickening of bowel walls (C).

In the proximal jejunum, immediately after the Treitz’s ligament, for an extension of about 150 cm, a large number of diverticula of 1–4 cm size were seen (Fig. 1A and B). The revision of CT picture according to the enteroscopy findings did not recognize any diverticula. The present case demonstrates the difficulty in diagnosing JD, mainly because, as a rare entity, many physicians do not suspect it. Nevertheless, even modern and accurate radiologic procedures such as CT-enteroclysis may fail in recognizing diverticula. The recently introduced capsule endoscopy and DAE offer a direct view of diverticula and are thus likely to be the most accurate diagnostic methods, but DAE should be preferred in case of suspected JD to the possible risk of capsule retention [3]. DAE is, however, not generally indicated in patients with such unspecific symptoms as those determined by JD, and, even in the presence of an obstructed patient, DAE is usually not performed. It is thus mandatory to consider also JD among the possible diagnoses in patients with bloating, abdominal pain, and obstruction and perform also DAE when other first line diagnostic procedures have failed to identify any causes for the symptoms. References [1] Noer T. Non-Meckelian diverticula of the small bowel: the incidence in an autopsy material. Acta Chir Scand 1960;25:175–9. [2] Liu Chia-Yuan, Chang Wen-Hsiung, Lin Shee-Chan, et al. Analysis of clinical manifestations of symptomatic acquired jejunoileal diverticular disease. World J Gastroenterol 2005;11(35):5557–60.