Pentosidine and Its Deposition in Renal Tissue in Renal Transplantation

Advanced glycation end products (AGEs) estimated by skin autofluorescence are related with cardiovascular risk in renal transplant

Background

Advanced glycation end products (AGEs) accumulation, a measure of cumulative metabolic stress, constitute a novel pathogenic mechanism involved in aging, diabetes, cardiovascular (CVD) and chronic kidney disease (CKD). Despite removal of uremic toxins and AGEs after a successful renal transplant (RT), CVD remains the leading cause of mortality. We hypothesized that AGEs measurement by Skin Autofluorescence (SAF) might be useful even after a successful RT and thus reflect the high cardiovascular risk burden of these patients.

Methods

189 stable RT (61% men, aged 56±13.0 years), CKD stages 1–4 and >12 months since RT were enrolled. Variables collected comprised comorbid history, medication use, smoking habit, routine biochemistry, subclinical atheromatosis by ankle-brachial-index (ABI) and allograft resistivity index (RI), 24-h ABPM, anthropometry and handgrip strength. AGEs were measured by SAF and expressed in arbitrary units (AU). Vascular age was estimated by Koetsier´s formula (SAF-0.83/0.024) and expected 10-years cardiovascular death risk was calculated with the REGICOR score.

Results

Mean SAF was 3.00±0.83 AU and estimated vascular age 90±34.7 years (30 years above biological age). SAF was higher among men (3.10±0.91 vs 2.81±0.66), diabetic nephropathy (3.49±0.75 vs 2.96±0.83) and steroid users (3.14±0.86 vs 2.71±0.69). We observed a positive correlation of SAF with night-systolic blood pressure (r = 0.25, p = 0.001), parathormone (r = 0.20, p<0.01), phosphate (r = 0.28, p<0.001) and negative with hemoglobin (r = -0.29, p<0.001), CKD-EPI (r = -0.32, p<0.001), albumin (r = -0.17, p<0.05), and dynamometry (r = -0.20, p<0.01). Subclinical vascular atheromatosis (ABI and RI) as well as the REGICOR scale (r = 0.35 p<0.001) were also correlated with SAF. In multivariable analysis age, gender, steroid use, serum phosphate and handgrip strength remained independently associated with SAF.

Conclusions

SAF levels are elevated in RT patients and correlate with CVD risk. Besides age and male sex, our results suggest that phosphate overload, steroid use and nutritional status are important factors linking to AGEs accumulation.

The AGE-RAGE pathway and its relation to cardiovascular disease in patients with chronic kidney disease

Chronic kidney disease (CKD) carries an unequivocal high risk for cardiovascular disease (CVD) contributing to high morbimortality; however, the underlying reasons are not fully known. Among mechanisms involved in the pathophysiology of CVD, chronic overstimulation of the advanced glycation end-products (AGE)-receptor for AGE (RAGE) pathway is likely a major contributor in patients with CKD. This review describes briefly some of the components of this pathway, highlighting especially differences between circulating AGE and tissue AGE and how activation of the AGE-RAGE pathway may promote CVD in CKD.