Proteomic analysis of Down's syndrome patients with gout.
BACKGROUND
In this study, the expression of hypoxanthine-guanine phosphoribosyl transferase (HPRT) in Down's syndrome patients with gout (DS/G) was determined, and possible underlying mechanisms of gout were characterized using proteomic tools.


METHODS
Serum was obtained from DS/G, healthy controls and gout patients (without DS), recruited from the rheumatology clinic. Baseline enzyme assays were recorded and RT-PCR used to identify HPRT gene expression. 2-D electrophoresis and mass spectrometry were utilized to determine a plausible explanation concerning the mechanisms leading to increased uric acid levels in DS patients.


RESULTS
Two DS patients were diagnosed with gouty arthritis. Their HPRT enzyme activity was slightly lower than that of normal controls. HPRT expression was also slightly decreased in DS/G patients compared with controls. Serum protein profiles of these two DS/G patients revealed that haptoglobin alpha chain and apolipoprotein A1 (ApoA1) were both significantly down-regulated. Protein expression was validated by immunoblot.


CONCLUSIONS
Our results revealed that low levels of haptoglobin in the two DS/G patients were related to renal dysfunction may have affected uric acid excretion and caused gout. However, decreased ApoA1 revealed a positive correlation between defective lipid metabolism and gouty arthritis in DS/G patients.
Chen
Ying-Chou
YC
Department of Rheumatology, Chang Gung Memorial Hospital, Kaohsiung, Taiwan.
Wang
Pei-Wen
PW
Pan
Tai-Long
TL
Wallace
Christopher Glenn
CG
Chen
Chung-Jen
CJ
D000328:Adult; D001798:Blood Proteins / Q000378:metabolism; D004314:Down Syndrome / Q000150:complications* / Q000235:genetics / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D006073:Gout / Q000150:complications* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000378:metabolism; D040901:Proteomics; D012333:RNA, Messenger / Q000235:genetics
D001798:Blood Proteins; D012333:RNA, Messenger; D007041:Hypoxanthine Phosphoribosyltransferase