Loss of RAGE Defense: A Cause of Charcot Neuroarthropathy?

OBJECTIVE: This study investigated the relationship between circulating soluble receptor for advanced glycation end products (sRAGE) and parameters of bone health in patients with Charcot neuroarthropathy (CNA). RESEARCH DESIGN AND METHODS: Eighty men (aged 55.3 ± 9.0 years), including 30 healthy control subjects, 30 type 2 diabetic patients without Charcot, and 20 type 2 diabetic patients with stage 2 (nonacute) CNA, underwent evaluations of peripheral and autonomic neuropathy, nerve conduction, markers of bone turnover, bone mineral density, and bone stiffness of the calcaneus. RESULTS: CNA patients had worse peripheral and autonomic neuropathy and a lower bone stiffness index than diabetic or control individuals (77.1, 103.3, and 105.1, respectively; P < 0.05), but no difference in bone mineral density (P > 0.05). CNA subjects also had lower sRAGE levels than control (162 vs. 1,140 pg/mL; P < 0.01) and diabetic (162 vs. 522 pg/mL; P < 0.05) subjects, and higher circulating osteocalcin levels. CONCLUSIONS: CNA patients had significantly lower circulating sRAGE, with an accompanying increase in serum markers of bone turnover, and reduced bone stiffness in the calcaneus not accompanied by reductions in bone mineral density. These data suggest a failure of RAGE defense mechanisms against oxidative stress in diabetes. Future studies should determine if medications that increase sRAGE activity could be useful in mitigating progression to CNA.