n(6)-(1-carboxyethyl)lysine and pentosidine

Chronic obstructive pulmonary disease (COPD) is associated with systemic inflammation and oxidative stress. These conditions may lead to the formation of advanced glycation end-products (AGEs). In this study we investigated in 88 COPD patients and 55 control subjects (80% ex-smokers) the association of the plasma protein-bound AGEs N(ε)-(carboxymethyl)lysine (CML), pentosidine, N(ε)-(carboxyethyl)lysine (CEL), and AGE accumulation in skin by skin autofluorescence (AFR), with lung function. Mean ± sd plasma CML was decreased (COPD 61.6 ± 15.6 nmol · mmol(-1) lysine, never-smokers 80.7 ± 19.8 nmol · mmol(-1) lysine and ex-smokers 82.9 ± 19.3 nmol · mmol(-1) lysine) and CEL (COPD 39.1 ± 10.9 nmol · mmol(-1) lysine, never-smokers 30.4 ± 5.0 nmol · mmol(-1) lysine and ex-smokers 27.7 ± 6.4 nmol · mmol(-1) lysine) and AFR (COPD 3.33 ± 0.67 arbitrary units (AU), never-smokers 2.24 ± 0.45 AU and ex-smokers 2.31 ± 0.47 AU) were increased in COPD patients compared to controls. Disease state was inversely associated with CML, and linearly associated with CEL and AFR. Performing regression analyses in the total group, CEL and AFR showed a negative association and CML a positive association with lung function, even after correction for potential confounders. In conclusion, CEL and AFR were negatively and CML was positively associated with disease state. In the total group only the AGEs showed an association with forced expiratory volume in 1 s. Our data suggest that AGEs are involved in the pathophysiology of COPD, although their exact role remains to be determined.

Topics: Aged; Arginine; Case-Control Studies; Female; Fluorescence; Glycation End Products, Advanced; Humans; Inflammation; Lung; Lysine; Male; Middle Aged; Oxidative Stress; Pulmonary Disease, Chronic Obstructive; Skin; Smoking; Spirometry

Experimental and histological data suggest a role for advanced glycation end products (AGEs) in cardiovascular disease (CVD), particularly in type 2 diabetes (T2DM). However, the epidemiological evidence of an adverse association between AGEs and CVD remains inconclusive. We therefore investigated, in individuals with various degrees of glucose metabolism, the associations of plasma AGEs with prevalent CVD.. We measured plasma levels of protein-bound N(ε)-(carboxymethyl)lysine (CML), N(ε)-(carboxyethyl)lysine (CEL), and pentosidine, in participants from two Dutch cohort studies (n = 1291, mean age 64.7 ± 8.3 years, 45% women), including 573 individuals with normal glucose metabolism, 304 with impaired glucose metabolism, and 414 with T2DM. In addition, we measured free CML, CEL, and 5-hydro-5-methylimidazolone in a subset of participants (n = 554). Data were analyzed with multiple logistic or linear regression analyses.. CEL (32 [interquartile range: 25-40] vs 28 [22-35] nmol/mmol lysine) and pentosidine (0.53 [0.43-0.67] vs 0.48 [0.40-0.59] nmol/mmol lysine) as well as free CEL (48 [39-62] vs 45 [36-56] nmol/L) and 5-hydro-5-methylimidazolone (141 [96-209] vs 116 [84-165] nmol/L) were higher in individuals with vs without CVD, whereas protein-bound CML was lower (33 [27-38] vs 34 [29-39] nmol/mmol lysine). However, these differences disappeared after adjustment for confounders. The associations did not differ consistently between individuals with and without T2DM.. We found no independent adverse associations of plasma AGEs with CVD in individuals with normal glucose metabolism, impaired glucose metabolism, and T2DM.

Topics: Aged; Arginine; Cardiovascular Diseases; Diabetes Mellitus, Type 2; Female; Glucose; Humans; Lysine; Male; Middle Aged

Advanced glycation end products (AGEs) are believed to play a significant role in the development of diabetic complications. In this study, we measured the levels of autoantibodies against several AGE structures in healthy human plasma and investigated the physiological role of the autoantibodies. A high titer of the autoantibody against N(ε)-(carboxyethyl)lysine (CEL) was detected in human plasma compared with other AGE structures such as CML and pentosidine. The purified human anti-CEL autoantibody reacted with CEL-modified human serum albumin (CEL-HSA), but not CML-HSA. A rabbit polyclonal anti-CEL antibody, used as a model autoantibody against CEL, accelerated the uptake of CEL-HSA by macrophages, but did not enhance the uptake of native HSA. Furthermore, when (125)I-labeled CEL-HSA was injected into the tail vein of mice, accumulation of (125)I-CEL-HSA in the liver was accelerated by co-injection of the rabbit anti-CEL antibody. These results demonstrate that the autoantibody against CEL in plasma may play a role in the macrophage uptake of CEL-modified proteins.

Topics: Animals; Arginine; Autoantibodies; Glycation End Products, Advanced; Humans; Lysine; Macrophages, Peritoneal; Mice; Rabbits; Serum Albumin

Oxidative stress plays an important role in the pathophysiology of sickle cell disease (SCD). Plasma levels of advanced glycation end products (AGEs) are increased under oxidative conditions and are associated with disease severity in diabetes and inflammatory diseases. We investigated whether AGEs are increased in sickle cell patients and whether they are associated with SCD-related complications. Plasma levels of the AGEs pentosidine, N(ε) -(carboxymethyl)lysine (CML) and N(ε) -(carboxyethyl)lysine (CEL) were measured using single-column high performance liquid chromatography with fluorescence detection (pentosidine) and ultra performance liquid chromatography-tandem mass spectrometry (CML and CEL). Plasma levels of pentosidine and CML were increased in HbSS/HbSβ⁰-thalassaemia (n=60) and HbSC/HbSβ(+) -thalassaemia (n=42) patients during steady state as compared to healthy HbAA controls (n=30) without increments during painful crisis. CEL levels were comparable between all groups. Pentosidine and CML levels correlated significantly to haemolytic rate during the clinically asymptomatic state while pentosidine was significantly related to the number of haemolysis-related organ complications. The increased plasma AGE levels in sickle cell patients and their association with haemolysis and haemolysis-related complications suggest AGEs might be implicated in the pathophysiology of the haemolytic phenotype of SCD. Measurement of AGEs might be useful in predicting organ complications in SCD.

Topics: Adolescent; Adult; Anemia, Sickle Cell; Arginine; Biomarkers; Female; Glycation End Products, Advanced; Hemolysis; Humans; Lysine; Male; Middle Aged; Oxidative Stress; Young Adult

Climatic droplet keratopathy (CDK), known as spheroid degeneration of the cornea, is one of the most frequent degenerative corneal disorders affecting visual function. However, the histochemical nature of the deposits seen in CDK is still unclear.. To investigate the pathogenesis of CDK, we investigated the immunohistochemical localisation of advanced glycation end products (AGEs) in surgical specimens of CDK.. Immunohistochemical localisation of N(epsilon)-(carboxymethyl)-l-lysine (CML), N(epsilon)-(carboxyethyl)-l-lysine (CEL), pyrraline, pentosidine and imidazolone was examined in three corneas with CDK, six corneas with bullous keratopathy and three corneas without any corneal diseases.. In all the specimens with CDK, immunoreactivity was strong in CML, moderate in pyrraline and pentosidine, and weak in imidazolone. Immunoreactivity was absent in CEL. In contrast, no immunoreactivity to CML, pyrraline, pentosidine, imidazolone or CEL was detected in corneas with bullous keratopathy, or in corneas without any corneal diseases.. CDK is caused by an aggregation of AGE-modified proteins. The result is consistent with etiological findings that ultraviolet irradiation and ageing, both of which are accelerators of AGE formation, are closely related to the development of CDK.

Topics: Antibodies, Monoclonal; Arginine; Cornea; Corneal Diseases; Cross-Linking Reagents; Female; Glycation End Products, Advanced; Humans; Immunohistochemistry; Lysine; Male; Middle Aged; Pyrroles

Despite their unfavourable cardiovascular risk profile, patients with glycogen storage disease type Ia (GSD Ia) do not develop premature atherosclerosis. We hypothesized that this paradox might be related to a decreased formation of advanced glycation end products (AGEs) resulting from lifetime low plasma glucose levels and decreased oxidative stress.. In 8 GSD Ia patients (age 20-34 years) and 30 matched controls we measured carotid intima-media thickness (IMT), skin autofluorescence (AF; a non-invasive index for AGEs), and specific AGEs (pentosidine, N-(carboxymethyl)lysine (CML), N-(carboxyethyl)lysine (CEL)) and collagen linked fluorescence (CLF, measured at excitation/emission wavelength combinations of 328/378 and 370/440 nm) in skin samples.. Carotid IMT was significantly lower in GSD Ia patients. Skin AF did not differ between patients and controls. The skin samples showed higher CEL levels in the patient group (p = 0.008), but similar levels of pentosidine, CML, and CLF. In the total group, skin AF correlated with CML (r = 0.39, p = 0.031), CLF 328/378 nm (r = 0.53; p = 0.002) and CLF 370/440 nm (r = 0.60; p = 0.001). In the control group, AF also correlated with the maximum carotid IMT (r = 0.6; p = 0.004).. Although our data confirm that GSD Ia patients present with a reduced burden of atherosclerosis, this phenomenon cannot be explained by differences in AGE accumulation as measured in the skin.

Topics: Adolescent; Adult; Arginine; Atherosclerosis; Carotid Arteries; Collagen; Female; Glycation End Products, Advanced; Glycogen Storage Disease Type I; Humans; Lysine; Male; Oxidative Stress; Risk; Skin; Tunica Intima; Tunica Media

Non-enzymic modification of tissue proteins by reducing sugars, the so-called Maillard reaction, is a prominent feature of aging. In articular cartilage, relatively high levels of the advanced glycation end product (AGE) pentosidine accumulate with age. Higher pentosidine levels have been associated with a stiffer collagen network in cartilage. However, even in cartilage, pentosidine levels themselves represent <1 cross-link per 20 collagen molecules, and as such cannot be expected to contribute substantially to the increase in collagen network stiffness. In the present study, we investigated a broad range of Maillard reaction products in cartilage collagen in order to determine whether pentosidine serves as an adequate marker for AGE levels. Not only did the well-characterized AGEs pentosidine, N(epsilon)-(carboxymethyl)lysine, and N(epsilon)-(carboxyethyl)lysine increase with age in cartilage collagen (all P<0.0001), but also general measures of AGE cross-linking, such as browning and fluorescence (both P<0.0001), increased. The levels of these AGEs are all higher in cartilage collagen than in skin collagen. As a functional measure of glycation the digestibility of articular collagen by bacterial collagenase was investigated; digestibility decreased linearly with age, proportional to the extent of glycation. Furthermore, the arginine content and the sum of the hydroxylysine and lysine content of cartilage collagen decrease significantly with age (P<0.0001 and P<0. 01 respectively), possibly due to modification by the Maillard reaction. The observed relationship between glycation and amino acid modification has not been reported previously in vivo. Our present results indicate that extensive accumulation of a variety of Maillard reaction products occurs in cartilage collagen with age. Altogether our results support the hypothesis that glycation contributes to stiffer and more brittle cartilage with advancing age.

Topics: Adolescent; Adult; Age Factors; Aged; Aged, 80 and over; Aging; Arginine; Cartilage, Articular; Child; Child, Preschool; Collagen; Collagenases; Cross-Linking Reagents; Female; Femur; Glycation End Products, Advanced; Humans; Lysine; Maillard Reaction; Male; Middle Aged; Skin; Spectrometry, Fluorescence

Collagen molecules in articular cartilage have an exceptionally long lifetime, which makes them susceptible to the accumulation of advanced glycation end products (AGEs). In fact, in comparison to other collagen-rich tissues, articular cartilage contains relatively high amounts of the AGE pentosidine. To test the hypothesis that this higher AGE accumulation is primarily the result of the slow turnover of cartilage collagen, AGE levels in cartilage and skin collagen were compared with the degree of racemization of aspartic acid (% d-Asp, a measure of the residence time of a protein). AGE (N(epsilon)-(carboxymethyl)lysine, N(epsilon)-(carboxyethyl)lysine, and pentosidine) and % d-Asp concentrations increased linearly with age in both cartilage and skin collagen (p < 0.0001). The rate of increase in AGEs was greater in cartilage collagen than in skin collagen (p < 0.0001). % d-Asp was also higher in cartilage collagen than in skin collagen (p < 0.0001), indicating that cartilage collagen has a longer residence time in the tissue, and thus a slower turnover, than skin collagen. In both types of collagen, AGE concentrations increased linearly with % d-Asp (p < 0.0005). Interestingly, the slopes of the curves of AGEs versus % d-Asp, i.e. the rates of accumulation of AGEs corrected for turnover, were identical for cartilage and skin collagen. The present study thus provides the first experimental evidence that protein turnover is a major determinant in AGE accumulation in different collagen types. From the age-related increases in % d-Asp the half-life of cartilage collagen was calculated to be 117 years and that of skin collagen 15 years, thereby providing the first reasonable estimates of the half-lives of these collagens.

Topics: Adolescent; Adult; Age Factors; Aged; Aged, 80 and over; Arginine; Aspartic Acid; Cartilage, Articular; Child; Child, Preschool; Chondrocytes; Collagen; Glycation End Products, Advanced; Humans; Kinetics; Lysine; Middle Aged; Skin