Skin Autofluorescence Is Associated with Endothelial Dysfunction in Uremic Subjects on Hemodialysis

Background

Elevated levels of advanced glycation end products (AGEs) within tissues may contribute to endothelial dysfunction, an early indicator of atherosclerosis. We aimed to investigate whether levels of skin AGEs could be a useful marker to predict endothelial dysfunction in uremic subjects on hemodialysis.

Methods and Results

One hundred and nineteen uremic patients on hemodialysis and 57 control subjects with moderate-to-high cardiovascular risk factors and without chronic kidney disease (CKD) were enrolled. We used ultrasound to measure flow-mediated vasodilation (FMD). An AGE reader measured skin autoflurorescence (AF). We then compared differences in FMD and skin AF values between the two groups. The uremic subjects had significantly higher levels of skin AF (3.47±0.76 AU vs. 2.21±0.45 arbitrary units; P<0.01) and significantly lower levels of FMD (4.79%±1.88% vs. 7.19%±2.17%; P<0.01) than the non-CKD subjects. After adjusting for all potential covariates, we found that skin AF level independently predicted FMD in both the hemodialysis and the non-CKD groups. In the hemodialysis group, skin AF ≥ 3.05 arbitrary units predicted abnormal FMD at a sensitivity of 87.9% and a specificity of 78.6% (P<0.01).

Conclusions

Skin AF could be a useful marker to predict endothelial dysfunction in uremic subjects on hemodialysis.     

An extracellular retinol-binding glycoprotein in the eyes of mutant rats with retinal dystrophy: development, localization, and biosynthesis

Interstitial retinol-binding protein (IRBP) is a soluble glycoprotein in the interphotoreceptor matrix of bovine, human, monkey, and rat eyes. It may transport retinol between the retinal pigment epithelium and the neural retina. In light-reared Royal College of Surgeons (RCS) and RCS retinal dystrophy gene (rdy)+ rats, the amount of IRBP in the interphotoreceptor matrix increased in corresponding proportion to the amount of total rhodopsin through postnatal day 22 (P22). In the RCS-rdy+ rats, the amount increased slightly after P23. However, in the RCS rats there was a rapid fall in the quantity of IRBP as the photoreceptors degenerated between P23 and P29. No IRBP was detected by immunocytochemistry in rats at P28. The amount of rhodopsin fell more slowly. Although retinas from young RCS and RCS-rdy+ rats were able to synthesize and secrete IRBP, this ability was lost in retinas from older RCS rats (P51, P88) but not their congenic controls. The photoreceptor cells have degenerated at these ages in the RCS animals, and may therefore be the retinal cells responsible for IRBP synthesis. The putative function of IRBP in the extracellular transport of retinoids during the visual cycle is consistent with a defect in retinol transport in the RCS rat reported by others.     

Increased Expression of Intranuclear Matrix Metalloproteinase 9 in Atrophic Renal Tubules Is Associated with Renal Fibrosis

Background

Reduced turnover of extracellular matrix has a role in renal fibrosis. Matrix metalloproteinases (MMPs) is associated with many glomerular diseases, but the histological association of MMPs and human renal fibrosis is unclear.

Methods

This is a retrospective study. Institutional Review Board approval was obtained for the review of patients’ medical records, data analysis and pathological specimens staining with waiver of informed consents. Specimens of forty-six patients were examined by immunohistochemical stain of MMP-9 in nephrectomized kidneys, and the association of renal expression of MMP-9 and renal fibrosis was determined. MMP-9 expression in individual renal components and fibrosis was graded as high or low based on MMP-9 staining and fibrotic scores.

Results

Patients with high interstitial fibrosis scores (IFS) and glomerular fibrosis scores (GFS) had significantly higher serum creatinine, lower estimated glomerular filtration rate (eGFR), and were more likely to have chronic kidney disease (CKD) and urothelial cell carcinoma. Univariate analysis showed that IFS and GFS were negatively associated with normal and atrophic tubular cytoplasmic MMP-9 expression and IFS was positively correlated with atrophic tubular nuclear MMP-9 expression. Multivariate stepwise regression indicated that MMP-9 expression in atrophic tubular nuclei (r = 0.4, p = 0.002) was an independent predictor of IFS, and that MMP-9 expression in normal tubular cytoplasm (r = −0.465, p<0.001) was an independent predictor of GFS.

Conclusions

Interstitial fibrosis correlated with MMP-9 expression in the atrophic tubular nuclei. Our results indicate that renal fibrosis is associated with a decline of MMP-9 expression in the cytoplasm of normal tubular cells and increased expression of MMP-9 in the nuclei of tubular atrophic renal tubules.     

Involvement of cathepsin E in exogenous antigen processing in primary cultured murine microglia.

We have attempted to elucidate an involvement of cathepsin E (CE) in major histocompatibility complex class II-mediated antigen presentation by microglia. In primary cultured murine microglia, CE was localized mainly in early endosomes and its expression level was markedly increased upon stimulation with interferon-gamma. Pepstatin A, a specific inhibitor of aspartic proteases, significantly inhibited interleukin-2 production from an OVA-(266-281)-specific T helper cell hybridomas upon stimulation with native OVA presented by interferon-gamma-treated microglia. However, pepstatin A failed to inhibit the presentation of OVA-(266-281) peptide. The possible involvement of CE in the processing of native OVA into antigenic peptide was further substantiated by that digested fragments of native OVA by CE could be recognized by OVA-specific Th cells. Cathepsin D also degraded native OVA into antigenic peptide, whereas microglia prepared from cathepsin D-deficient mice retained an ability for antigen presentation. On the other hand, the requirement for cysteine proteases such as cathepsins S and B in the processing of invariant chain (Ii) was confirmed by immunoblot analyses in the presence of their specific inhibitors. In conclusion, CE is required for the generation of an antigenic epitope from OVA but not for the processing of Ii in microglia.     

Tissue-specific expression in transgenic mice directed by the 5'-flanking sequences of the human gene encoding interphotoreceptor retinoid-binding protein

Interphotoreceptor retinoid-binding protein (IRBP) is an extracellular protein that has been suggested to participate in the visual process as a carrier for visual retinoids. A chimeric gene composed of the human IRBP promoter fused to the bacterial reporter gene chloramphenicol acetyltransferase (CAT) was used to generate transgenic mice. Analysis of six transgenic families revealed that the CAT gene, concomitant with the endogenous IRBP gene, was expressed primarily in the retina and, to a lesser extent, in the pineal gland. These results establish that a 1.3-kilobase fragment from the 5' end of the human IRBP gene is sufficient to direct transgene expression to a visual subdivision of the central nervous system.     

Mouse/human chimeric anti-HIV-1 gp120 antibody to the principal neutralizing determinant: Tolerability and pharmacokinetics in cynomolgus monkeys,Macaca fascicularis

In preparing for testing a pharmaceutical grade preparation of chimeric (mouse/human) antibody CGP 47 439 in HIV-1 infected individuals, it was administered toMacaca fascicularis (cynomolgus) monkeys to study tolerability, immunogenicity and pharmacokinetics. Four groups of monkeys, three males and three females per group, received respectively four infusions of 0, 1.43, 4.3, and 14.3 mg of CGP 47 4391 kg body weight at one-week intervals. The chimeric antibody induced no fever, was tolerated well throughout the 50-day observation period, elicited no tissue damage and no anti-antibody response. The pharmacokinetic profile was similar at all dose levels with a mean T_1/2 of 14.2 h (range 11.8–19.3 h) and a mean T_1/2 of 172.6h (range 137.2–220.5h). Following four successive antibody infusions serum concentrations of CGP 47 439 increased without reaching a steady state, and its measured concentrations were comparable to the simulated values. Collectively the study has provided safety and pharmacokinetic data that would allow human studies with this antibody in AIDS patients.