mRNA levels of TLR4 and TLR5 are independent of H pylori.
ABSTRACT To determine if the presence H pylori or its virulence affect toll-like receptor 4 (TLR4) and TLR5 mRNA expression levels.
For the in vivo assays, gastric biopsies were obtained from 40 patients and H pylori status was determined. For the in vitro assays, human gastric adenocarcinoma mucosal cells (AGS) were cultured in the presence or absence of twelve selected H pylori strains. H pylori strains isolated from culture-positive patients and selected strains were genotyped for cagA and vacA. The cDNA was obtained from mRNA extracted from biopsies and from infected AGS cells. TLR4 and TLR5 mRNA levels were examined by real-time PCR.
The presence of H pylori did not affect the mRNA levels of TLR4 or TLR5 in gastric biopsies. The mRNA levels of both receptors were not influenced by the vacA status (P > 0.05 for both receptors) and there were no differences in TLR4 or TLR5 mRNA levels among the different clinical presentations/histological findings (P > 0.05). In the in vitro assay, the mRNA levels of TLR4 or TLR5 in AGS cells were not influenced by the vacAs1 status or the clinical condition associated with the strains (P > 0.05 for both TLR4 and TLR5).
The results of this study show that the mRNA levels of TLR4 and TLR5 in gastric cells, both in vivo and in vitro, are independent of H pylori colonization and suggest that vacA may not be a significant player in the first step of innate immune recognition mediated by TLR4 or TLR5.
Article: Mosaicism in vacuolating cytotoxin alleles of Helicobacter pylori. Association of specific vacA types with cytotoxin production and peptic ulceration.[show abstract] [hide abstract]
ABSTRACT: Approximately 50% of Helicobacter pylori strains produce a cytotoxin, encoded by vacA, that induces vacuolation of eukaryotic cells. Analysis of a clinically isolated tox- strain (Tx30a) indicated secretion of a 93-kDa product from a 3933-base pair vacA open reading frame. Characterization of 59 different H. pylori isolates indicated the existence of three different families of vacA signal sequences (s1a, s1b, and s2) and two different families of middle-region alleles (m1 and m2). All possible combinations of these vacA regions were identified, with the exception of s2/m1 (p < 0.001); this mosaic organization implies that recombination has occurred in vivo between vacA alleles. Type s1/m1 strains produced a higher level of cytotoxin activity in vitro than type s1/m2 strains; none of 19 type s2/m2 strains produced detectable cytotoxin activity. The presence of cagA (cytotoxin-associated gene A) was closely associated with the presence of vacA signal sequence type s1 (p < 0.001). Among patients with past or present peptic ulceration, 21 (91%) of 23 harbored type s1 strains compared with 16 (48%) of 33 patients without peptic ulcers; only 2 (10%) of 19 subjects harboring type s2 strains had past or present peptic ulcers (p < 0.005). Thus, specific vacA genotypes of H. pylori strains are associated with the level of in vitro cytotoxin activity as well as clinical consequences.Journal of Biological Chemistry 08/1995; 270(30):17771-7. · 4.77 Impact Factor