Gek Keow Lim

Persistent Helicobacter pylori specific Th17 responses in patients with past H. pylori infection are associated with elevated gastric mucosal IL-1β.

Background Ongoing Helicobacter pylori (HP) infection triggers a chronic active gastritis. Eradicating HP reduces gastric inflammation, but does not eliminate it. We sought to characterize this persistent gastritis, and demonstrate the persistence of HP-specific Th17 responses in individuals previously infected with HP but who no longer had evidence of ongoing infection. Methodology/Principal Findings Study subjects were divided into 3 groups 55 individuals had active HP infection (group A), 41 were diagnosed with previous HP infection (group P), and 59 were naïve to HP (group N). Blood and gastric tissue were obtained with written informed consent from all subjects, and immune responses were evaluated using flow cytometry, semi-quantitative real time PCR, immunofluorescent staining, ELISA, and multiplex cytometric bead array for cytokine quantification. Elevated IL-17A responses were observed in patients from group A compared to group N. Interestingly, IL-17A responses remained persistently elevated in the blood and gastric mucosa of individuals from group P, despite the absence of ongoing HP infection. Using purified CD4+ T cells as effectors and antibodies that blocked antigen presentation by MHC Class II, we showed that these persistent IL-17A responses were mediated primarily by HP-specific Th17 cells, rather than other immune cells that have also been described to secrete IL-17A. Gastric mucosal IL-1β levels were also persistently elevated in group P, and neutralisation of IL-1β reduced the HP-specific IL-17A response of purified CD4+ T cells to autologous HP-pulsed antigen presenting cells in vitro, suggesting a functional association between IL-1β and the persistent Th17 response in group P patients. Conclusions/Significance Despite lack of ongoing HP infection, HP-specific Th17 cells persist in the blood and gastric mucosa of individuals with past HP infection. We speculate that this persistent inflammation might contribute to gastric mucosal pathology, for example, persistent increased gastric cancer risk despite eradication of HP.

Wild-type and 'a' epitope variants in chronic hepatitis B virus carriers positive for hepatitis B surface antigen and antibody.

Aims This study aims to examine the genomic variants of the ‘a’ epitope in chronic hepatitis B virus (HBV) carriers positive for both hepatitis B surface antigen (HBsAg) and antibody to HBsAg (anti‐HBs).

Gastric Cancer: Increased Numbers of Myeloid-Derived Suppressor Cells Are Found in Gastric Cancer Patients

Gastric cancer is one of the most common neoplasms, ranking as the second leading cause of cancer-related deaths worldwide. The predominant factor associated to gastric cancer is Helicobacter pylori infection, which leads to a chronic inflammatory response and subsequent oxyntic atrophy. Parietal cell loss result in two types of metaplasia, the intestinal metaplasia (IM) characterized by the presence of cells with goblet cell morphology and spasmolytic polypeptide-expressing metaplasia (SPEM) that shows morphological characteristics of the deep antral glands and express trefoil factor 2 (spasmolytic polypeptide). Although metaplastic lesions are considered neoplastic precursors, their direct association to cancer is still in debate. Similar to other cancers, gastric cancers are marked by global gene expression alterations. MicroRNAs (miRNAs) are small noncoding RNAs involved in the post-transcriptional regulation of gene expression and an increasing number of studies has been showing their aberrant expression in cancer. In order to identify miRNAs involved in the early stages of gastric cancer we performed a miRNA profiling on laser capture micro-dissected IM and SPEM cells from patient lesions. Using a qRT-PCR approach for quantitation of 754 human miRNAs, we identified 77 miRNAs differentially expressed in the metaplastic samples (greater than two-fold) in comparison to normal chief cells. The highest number of dysregulated miRNAs was observed in IM,which showed 45 up-regulated and 25 down-regulatedmiRNAs. In SPEM, 28 miRNAs were found up-regulated (21 of them also up-regulated in IM), whereas no down-regulation was detected. Some of the up-regulated miRNAs have already been associated to cancer in general (miR-26-a, miR-191, miR-155), as well as specifically to gastric cancer (miR-18b, miR-196b and miR-106a). However, the regulation of some of the top up-regulated miRNAs revealed here including miR-802, miR-922 and miR-622 are still poorly characterized in cancer. In a comparison with a previous mRNA profiling study performed on a similar group of samples, we observed that 108 out of the 568 mRNAs found up-regulated in IM are predicted targets of the 26 microRNAs down-regulated in IM, revealing a potential mechanism for the regulation of those genes in gastric metaplasia. Particularly interesting are 4 members of the miR-30 family, with 31 predicted mRNA targets amongst those up-regulated in IM. Although miR-30 family members have been described as down-regulated in gastric cancer, no data on their targets in this neoplasia is currently available. An extended characterization of the microRNAs identified here will provide a better understanding of their function in gastric metaplasia and progression to neoplasia, as well as might reveal useful early stage biomarkers or therapeutic targets.

Significance of the minor i and t determinants of hepatitis B virus in hepatocellular carcinoma

Stored sera from asymptomatic hepatitis B virus (HBV) carriers and hepatitis B virus surface antigen‐positive hepatocellular carcinoma (HCC) patients were tested for HBV subtypes, such as subtype determinants d, y, w, r and also antigenic determinants isoleucine (i) and threonine (t) by direct S gene nucleotide sequencing. Significant changes in minor i and t determinants in hepatocellular carcinoma patients with adr hepatitis B carriers were seen. The adr subtype with t determinant was present in 14/25 (56%) of HCC patients compared with only two of 28 (7%) in asymptomatic hepatitis B carriers (P < 0.001). However, the adr subtype with i determinant was present in nine of 25 (36%) of the HCC patients and also present in 24/28 (86%) of asymptomatic carriers (P < 0.001). No significant changes were seen with the adw subtypes. These results show that i and t minor determinant changes are more common with adr subtypes associated with HCC than with the adw subtype. Whether these subtle changes are pathologically relevant or only a polymorphism of hepatitis B genotypes will depend on subsequent follow‐up studies.