Anti-inflammatory effect of capsaicin in Helicobacter pylori-infected gastric epithelial cells.

BACKGROUND AND AIM: Capsaicin, the main pungent ingredient of hot red and chilli pepper, has been considered as not only a cytoprotective but also a detrimental agent to the gastric mucosa. However, the effect and mechanism of capsaicin that modulate the induction of pro-inflammatory cytokine in Helicobacter pylori-infected epithelial cells have not been investigated previously. Herein, we demonstrated that capsaicin inhibited the release of pro-inflammatory cytokine, interleukin-8 (IL-8) by H. pylori-infected gastric epithelial cells through nuclear factor-kappaB (NF-kappaB) signal pathway. MATERIALS AND METHODS: AGS or MKN45 cells as gastric epithelial cells and Vac A+, CagA+ wild-type H. pylori strain ATCC 49503 were used. Gastric epithelial cells were pre-treated with various concentrations of capsaicin and infected with H. pylori for different periods of time to determine IL-8 concentrations in culture supernatant by an ELISA assay. We measured IL-8 mRNA transcripts in H. pylori-infected gastric epithelial cells co-treated with capsaicin by reverse transcriptase-polymerase chain reaction analysis. We performed electrophoretic mobility shift assay to examine the NF-kappaB DNA binding activity with capsaicin and immunofluorescence microscopy to examine nuclear staining of p65. We also performed immunoblotting for IkappaB, IKK activity with capsaicin. RESULTS: Capsaicin inhibits H. pylori-induced IL-8 production by gastric epithelial cells in dose- and time-dependent manner. Capsaicin as low as 100 micromol/L significantly inhibited IL-8 production in H. pylori-infected MKN45 cells (43.2% of control) at 24 hours incubation, whereas inhibited IL-8 production in H. pylori-infected AGS cells (70% of control). We confirmed that capsaicin inhibited IL-8 mRNA expression after infection of gastric epithelial cells with H. pylori for 6 hours. The addition of capsaicin (100 micromol/L) suppressed H. pylori-induced NF-kappaB activation in gastric epithelial cells at 1 hour post-infection. We also found that the degradation of IkappaB and IKK activation were inhibited by capsaicin. CONCLUSIONS: Nontoxic dose of capsaicin inhibited H. pylori-induced IL-8 production by gastric epithelial cells through the modulation of IkappaB-, NF-kappaB-, and IL-8 pathways. We conclude that capsaicin can be proposed as a potential anti-inflammatory drug by inhibition of the production of IL-8 in H. pylori-infected gastric epithelium.

Isogenic variation of Helicobacter pylori strain resulting in heteroresistant antibacterial phenotypes in a single host in vivo.

BACKGROUND: Antibiotic-susceptible and -resistant Helicobacter pylori can be present simultaneously in the same host. The aim of this study was to evaluate the genomic diversity of H. pylori strains resulting in heteroresistant antibacterial phenotypes. MATERIALS AND METHODS: Twenty-one pairs of H. pylori strains isolated from the antrum and body displaying heteroresistant antibacterial phenotypes were included. We compared the genotypes of paired-isolates by random arbitrarily primed polymerase chain reaction (PCR), flagella gene PCR-based restriction fragment length polymorphism, and flaA gene sequencing. In metronidazole-heteroresistant isolates, the sequence variation of rdxA and frxA genes was analyzed using phylogenetic analysis. RESULTS: The DNA fingerprinting patterns of the paired isolates revealed that 12 pairs (57.1%) were identical, whereas one pair (3.8%) was different. The remaining eight pairs (38.1%) of isolates showed minor heterogenecity in fingerprinting patterns. In flaA gene sequencing, these identical and similar isolates showed close sequence similarity between the antrum and body, whereas different isolate showed 31 points of different nucleotide sequences. Phylogenetic analysis of the metronidazole-heteroresistant pairs showed consistent genetic relatedness of each paired isolates despite the sequence variation of the rdxA or frxA genes in five pairs (71.4%). CONCLUSIONS: These results suggest that continuing genomic diversities in the same strain may play an important role in modulating the antibiotic-heteroresistant H. pylori in vivo.