W. Freitas et al., A heat labile soluble factor from Bacteroides thetaiotaomicron VPI-5482 specifically increases the galactosylation pattern of HT29-MTX cells, CELL MICROB, 3(5), 2001, pp. 289-300
The aim of this work was to set up and validate an in vitro model to study
a molecular response of an intestinal host cell line (HT29-MTX), to a non-p
athogen microflora component We found that Bacteroides thetaiotaomicron str
ain VPI-5482 had the capacity to change a specific glycosylation process in
HT29-MTX cells via a mechanism that involved a soluble factor. Differentia
ted HT29-MTX cells were grown in the presence of 20% of spent culture super
natant from the B. thetaiotaomicron during 10 days, Glycosylation processes
were followed using a large panel of lectins and analysed using confocal m
icroscopy, western blotting and flow cytometry techniques. Our results show
that a B. thetaiotaomicron soluble factor modified specifically the galact
osylation pattern of HT29-MTX cells, whereas other glycosylation steps rema
ined mainly unaffected. Further characterization of this soluble factor ind
icates that it is a heat labile, low molecular weight compound. Reverse tra
nscript-PCR (RT-PCR) analysis was unable to show any significant change in
mRNA expression level of the main galactosyltransferases expressed in HT29-
MTX cells. By contrast, galactosyltransferase activities dramatically incre
ased in HT29-MTX cells treated by the soluble extract of B, thetaiotaomicro
n, suggesting a post-translational regulation of these activities. Our in v
itro model allowed us to study the cross-talk between a single bacteria and
intestinal cells. The galactosylation process appears to be a target of th
is communication, thus uncovering a new window to study the functional cons
equences of co-operative symbiotic bacterial-host interactions.