Evaluation of Glycan Profiles of Tamm-horsfall Glycoprotein and Uromodulin

Uromodulin is well-known to be the more potent immunosuppressive glycoprotein isolated from pregnant women urine, compared to its counterpart, Tamm-Horsfall glycoprotein (THP) isolated from non-pregnant women/male urine. However, structural profiles of these glycoproteins were controversial until today. Hence, this paper aims to identify the pregnancy associated glycosylation changes of THP and uromodulin. THP and uromodulin isolated with diatomaceous earth filtration were subjected for structural characterization using MALDI-TOF tandem mass spectrometry (MS) analyses. Both THP and uromodulin expressed high-mannose and complex-type N-glycan carrying Sda, LacNAc, LacdiNAc sequence as the capping antennae. In comparison to THP, uromodulin expressed higher abundance of LacdiNAc sequence and heavily sialylated complex type Nglycans, where up to four sialic acid residues were observed in its tetra-antennary glycans. Both THP and uromodulin expressed Core 1 and Core 2 O-glycans. These findings suggested that the higher level of LacdiNAc sequence and sialylation in uromodulin might facilitate its lymphocyte suppressive response more effectively than that of THP.