| Abstract | dc.description.abstract | Objectives. To determine the expression and enzymatic activities of sulphotransferases involved in mucin
hyposulphation in labial salivary glands (LSGs) from SS patients and to correlate sulphotransferase activity
with clinical parameters such as secretion, inflammation and serology.
Methods. LSG from 31 SS patients and 31 control subjects were studied. Relative mRNA and protein
levels of Gal3-O-sulphotransferases (Gal3STs) and b1,3-galactosyltransferase-5 (b3GalT5) were determined
by quantitative RT-PCR and western blotting, respectively. Enzymatic activities were quantified
using radioactively labelled donor substrates and specific acceptor substrates. Products were purified
by chromatography. Spearman’s correlation analysis was used to compare data.
Results. The levels of Gal3ST activity were significantly decreased in SS patients, without changes in
mRNA and protein levels, while the enzymatic activities of glycosyltransferases involved in mucin glycosylation
were similar in both groups. An inverse correlation was observed between Gal3ST activity and
glandular function measured by scintigraphy, but not with unstimulated salivary flow. Gal3ST activity was
inversely correlated with focus score, TNF-a levels and presence of the autoantibodies Ro/SS-A and
La/SS-B.
Conclusion. The decrease in sulphotransferase activity provides an explanation for mucin hyposulphation
observed in the LSGs from SS patients. The decrease in Gal3STs activity was not a consequence of
reduced gene expression, but probably due to alterations in the enzyme activity regulation. Interestingly,
the levels of sulphotransferase activity detected correlated well with secretory function, inflammation and
serology. Finally, we postulate that pro-inflammatory cytokines induced by autoantibodies, such as
Ro/SS-A and La/SS-B in SS patients, may modulate Gal3ST activity, thereby altering mucin quality and
leading to mouth dryness. | es_CL |
