Helicobacter pylori infection and short-term intake of low-dose aspirin have different effects on alpha-1 antitrypsin/alpha-1 peptidase inhibitor (alpha1-PI) levels in antral mucosa and peripheral blood

Expression profile of genes involved in pathogenesis of pediatric Crohn's disease

BACKGROUND AND AIM

Expression profiling of genes specific to pediatric Crohn's Disease (CD) patients was performed to elucidate the molecular mechanisms underlying disease cause and pathogenesis at disease onset.

METHODS

We used suppressive subtractive hybridization (SSH) and differential screening analysis to profile the mRNA expression patterns of children with CD and age- and sex-matched controls without inflammatory bowel disease (IBD).

RESULTS

Sequence analysis of 1000 clones enriched by SSH identified 75 functionally annotated human genes, represented by 430 clones. The 75 genes have potential involvement in gene networks, such as antigen presentation, inflammation, infection mechanism, connective tissue development, cell cycle and cancer. Twenty-eight genes were previously described in association with CD, while 47 were new genes not previously reported in the context of IBD. Additionally, 29 of the 75 genes have been previously implicated in bacterial and viral infections. Quantitative real-time reverse transcription polymerase chain reaction performed on ileal-derived RNA from 13 CD and nine non-IBD patients confirmed the upregulation of extracellular matrix gene MMP2 (P = 0.001), and cell proliferation gene REG1A (P = 0.063) in our pediatric CD cohort.

CONCLUSION

The retrieval of 28 genes previously reported in association with adult CD emphasizes the importance of these genes in the pediatric setting. The observed upregulation of REG1A and MMP2, and their known impact on cell proliferation and extracellular matrix remodeling, agrees with the clinical behavior of the disease. Moreover, the expressions of bacterial- and virus-related genes in our CD-patient tissues support the concept that microbial agents are important in the etiopathogenesis of CD.

Protease-activated receptor-2 (PAR2) in human gastric mucosa as mediator of proinflammatory effects in Helicobacter pylori infection

INTRODUCTION

Protease-activated receptors (PAR) are seven transmembrane receptors that are expressed throughout the gastrointestinal tract. In vitro experiments using gastric tumor cell lines, murine models and one clinical study provided evidence for a potential role of PAR2 in Helicobacter pylori-induced gastritis.

AIM

To investigate PAR2 expression in H. pylori-infected patients and correlation with proinflammatory IL-8, IL-1β as well as histologic changes of the mucosa. Furthermore, PAR2 expression was studied in context to mucosal amounts of secretory leukocyte protease inhibitor (SLPI), a putative regulator of PAR2.

METHODS

Twenty-two H. pylori-infected patients and 72 H. pylori-negative subjects underwent upper GI endoscopy. In antrum-derived mucosal biopsies, PAR2, IL-1β, IL-8, and SLPI expression was analyzed by quantitative RT-PCR, and in part by ELISA and immunohistochemistry. Histopathologic evaluation of gastritis was performed according to the updated Sydney classification.

RESULTS

IL-8 gene expression was 5-fold increased in the mucosa of H. pylori-infected patients compared with non-infected (p < .0001), whereas no differences for PAR2 and IL-1β mRNA amounts were observed between both groups. PAR2 gene expression correlated positively with transcript levels of IL-8, IL-1β as well mucosal SLPI levels in H. pylori-infected patients (r: 0.47-0.84; p < .0001), whereas no correlation was found with the degree of gastritis.

CONCLUSIONS

PAR2 represents an additive pathway of IL-8 secretion and proinflammatory effects in H. pylori-induced gastritis. Reduced SLPI levels leading to higher serine protease activities in the mucosa of infected subjects might regulate PAR2 activation.

Mucosal Progranulin expression is induced by H. pylori, but independent of Secretory Leukocyte Protease Inhibitor (SLPI) expression

Background

Mucosal levels of Secretory Leukocyte Protease Inhibitor (SLPI) are specifically reduced in relation to H. pylori-induced gastritis. Progranulin is an epithelial growth factor that is proteolytically degraded into fragments by elastase (the main target of SLPI). Considering the role of SLPI for regulating the activity of elastase, we studied whether the H. pylori-induced reduction of SLPI and the resulting increase of elastase-derived activity would reduce the Progranulin protein levels both ex vivo and in vitro.

Methods

The expression of Progranulin was studied in biopsies of H. pylori-positive, -negative and -eradicated subjects as well as in the gastric tumor cell line AGS by ELISA, immunohistochemistry and real-time RT-PCR.

Results

H. pylori-infected subjects had about 2-fold increased antral Progranulin expression compared to H. pylori-negative and -eradicated subjects (P < 0.05). Overall, no correlations between mucosal Progranulin and SLPI levels were identified. Immunohistochemical analysis confirmed the upregulation of Progranulin in relation to H. pylori infection; both epithelial and infiltrating immune cells contributed to the higher Progranulin expression levels. The H. pylori-induced upregulation of Progranulin was verified in AGS cells infected by H. pylori. The down-regulation of endogenous SLPI expression in AGS cells by siRNA methodology did not affect the Progranulin expression independent of the infection by H. pylori.

Conclusions

Taken together, Progranulin was identified as novel molecule that is upregulated in context to H. pylori infection. In contrast to other diseases, SLPI seems not to have a regulatory role for Progranulin in H. pylori-mediated gastritis.

Influence of cyclooxygenase inhibitors on the function of the prostaglandin transporter organic anion-transporting polypeptide 2A1 expressed in human gastroduodenal mucosa

The human organic anion-transporting polypeptide 2A1 (OATP2A1) is a prostaglandin transporter expressed in several tissues and plays an important role for local distribution of prostaglandins, which contribute to the integrity of gastric mucosa. Blockade of prostaglandin pathways by cyclooxygenase (COX) inhibitors has been associated with serious side effects such as gastrointestinal ulceration and bleeding. However, little is known regarding OATP2A1 expression in the upper gastrointestinal tract and the potential impact of cyclooxygenase inhibitors on OATP2A1 function. We first investigated the expression of OATP2A1 mRNA and protein in human gastroduodenal mucosa using human biopsy specimens obtained from antrum, corpus, and duodenum. The results indicate that OATP2A1 is expressed in the neck region and deep pyloric glands of antrum and in parietal cells of gastric corpus. Second, we examined various COX inhibitors for their effects on OATP2A1 transporter activity. Using HEK293 cells expressing OATP2A1, we found that diclofenac and lumiracoxib are potent inhibitors of OATP2A1-mediated transport of prostaglandin (PG) E(2) with IC(50) values of 6.2 +/- 1.2 and 3.1 +/- 1.2 microM. In contrast, indomethacin, ketoprofen, and naproxen led to significant stimulation of OATP2A1-mediated PGE(2) transport by 162.7 +/- 13.9, 77.2 +/- 3.6, and 32.3 +/- 4.9%, respectively. Taken together, our results suggest that various clinically used COX inhibitors have differential impact on the function of the prostaglandin transporter OATP2A1 in human stomach and that these effects may contribute to differences in the gastrointestinal side effects of COX inhibitors.

Low-dose aspirin has no impact on systemic level of serine protease inhibitors in healthy volunteers

Low-dose aspirin (100 mg/day) was recently found to increase serum levels of alpha-1 protease inhibitor (A1-PI). Here, we studied the serum levels of 2 major serine protease inhibitors, A1-PI and serine leukocyte protease inhibitor (SLPI), in 10 Helicobacter pylorinegative healthy volunteers (HVs) treated with low-dose aspirin alone and in combination with other drugs.(1) Neither the treatment with low-dose aspirin alone or in combination altered serum levels of both serine protease inhibitors. The previously described increase of A1-PI levels by low-dose aspirin was most likely caused by multiple endoscopies within a few days, which caused a systemic stress response.