The expression of acute-phase
serum proteins increases in response to inflammatory stimuli. Most of these
proteins are
glycoproteins that often contain
sialic acids (Sia). It is unknown, however, how the expression of Sia in these
glycoproteins changes during
inflammation. This study demonstrates changes in the alpha2,3-, alpha2,6-, and alpha2,8-Sia glycotopes on serum
glycoproteins in response to
turpentine oil-induced
inflammation, based on
lectin- and immunoblot analyses by using sialyl linkage-specific
lectins, Maackia amurensis for the alpha2,3-Sia glycotope and Sambucus sieboldiana for the alpha2,6-Sia glycotopes, and
monoclonal antibody 2-4B (mAb.2-4B) recognizing the di- and oligomers of the alpha2,8-Neu5Gc residue. There was an increase in a limited number of
sialoglycoproteins containing the alpha2,3-, alpha2,6-, or alpha2,8-Sia glycotopes. Reverse transcription-polymerase chain reaction (RT-PCR) analysis of the expression profiles of mRNAs for the known
sialyltransferases in mouse liver during
inflammation indicated the up-regulated expression of
beta-galactoside alpha2,3-sialyltransferases (
ST3Gal I and
ST3Gal III) and beta-N-acetylgalactosaminide alpha2,6-sialyltransferase (
ST6GalNAc VI) as well as
beta-galactoside alpha2,6-sialyltransferase (
ST6Gal I) mRNAs. Notably,
ST3Gal I and III and
ST6GalNAc VI are involved in the synthesis of the alpha2,3- and alpha2,6-Sia glycotopes on O-
glycan chains and possibly on
gangliosides, whereas
ST6Gal I is specific for N-
glycan chains. These results provide evidence for the
inflammation-induced expression of sialyl glycotopes in serum
glycoproteins. We demonstrated that
inflammation significantly increased the expression of an unknown 32-kDa
glycoprotein containing the alpha2,8-Sia glycotope. The mechanism for the increase in
glycoprotein in inflamed mouse serum remains to be examined, as
mRNA expression for all of the alpha2,8-sialyltransferases (ST8Sia I-VI) was unchanged during
inflammation.