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1.
Gut ; 71(8): 1577-1587, 2022 08.
Article in English | MEDLINE | ID: mdl-34697034

ABSTRACT

OBJECTIVE: Although gut dysbiosis is increasingly recognised as a pathophysiological component of metabolic syndrome (MetS), the role and mode of action of specific gut microbes in metabolic health remain elusive. Previously, we identified the commensal butyrogenic Anaerobutyricum soehngenii to be associated with improved insulin sensitivity in subjects with MetS. In this proof-of-concept study, we investigated the potential therapeutic effects of A. soehngenii L2-7 on systemic metabolic responses and duodenal transcriptome profiles in individuals with MetS. DESIGN: In this randomised double-blind placebo-controlled cross-over study, 12 male subjects with MetS received duodenal infusions of A. soehngenii/ placebo and underwent duodenal biopsies, mixed meal tests (6 hours postinfusion) and 24-hour continuous glucose monitoring. RESULTS: A. soehngenii treatment provoked a markedly increased postprandial excursion of the insulinotropic hormone glucagon-like peptide 1 (GLP-1) and an elevation of plasma secondary bile acids, which were positively associated with GLP-1 levels. Moreover, A. soehngenii treatment robustly shaped the duodenal expression of 73 genes, with the highest fold induction in the expression of regenerating islet-protein 1B (REG1B)-encoding gene. Strikingly, duodenal REG1B expression positively correlated with GLP-1 levels and negatively correlated with peripheral glucose variability, which was significantly diminished in the 24 hours following A. soehngenii intake. Mechanistically, Reg1B expression is induced upon sensing butyrate or bacterial peptidoglycan. Importantly, A. soehngenii duodenal administration was safe and well tolerated. CONCLUSIONS: A single dose of A. soehngenii improves peripheral glycaemic control within 24 hours; it specifically stimulates intestinal GLP-1 production and REG1B expression. Further studies are needed to delineate the specific pathways involved in REG1B induction and function in insulin sensitivity. TRIAL REGISTRATION NUMBER: NTR-NL6630.


Subject(s)
Diabetes Mellitus, Type 2 , Insulin Resistance , Metabolic Syndrome , Blood Glucose/metabolism , Blood Glucose Self-Monitoring , Clostridiales , Cross-Over Studies , Diabetes Mellitus, Type 2/drug therapy , Double-Blind Method , Glucagon-Like Peptide 1/metabolism , Glycemic Control , Humans , Insulin/metabolism , Male , Metabolic Syndrome/genetics , Transcriptome
2.
Eur Heart J ; 43(6): 518-533, 2022 02 10.
Article in English | MEDLINE | ID: mdl-34597388

ABSTRACT

AIMS: Atherosclerotic cardiovascular disease (ACVD) is a major cause of mortality and morbidity worldwide, and increased low-density lipoproteins (LDLs) play a critical role in development and progression of atherosclerosis. Here, we examined for the first time gut immunomodulatory effects of the microbiota-derived metabolite propionic acid (PA) on intestinal cholesterol metabolism. METHODS AND RESULTS: Using both human and animal model studies, we demonstrate that treatment with PA reduces blood total and LDL cholesterol levels. In apolipoprotein E-/- (Apoe-/-) mice fed a high-fat diet (HFD), PA reduced intestinal cholesterol absorption and aortic atherosclerotic lesion area. Further, PA increased regulatory T-cell numbers and interleukin (IL)-10 levels in the intestinal microenvironment, which in turn suppressed the expression of Niemann-Pick C1-like 1 (Npc1l1), a major intestinal cholesterol transporter. Blockade of IL-10 receptor signalling attenuated the PA-related reduction in total and LDL cholesterol and augmented atherosclerotic lesion severity in the HFD-fed Apoe-/- mice. To translate these preclinical findings to humans, we conducted a randomized, double-blinded, placebo-controlled human study (clinical trial no. NCT03590496). Oral supplementation with 500 mg of PA twice daily over the course of 8 weeks significantly reduced LDL [-15.9 mg/dL (-8.1%) vs. -1.6 mg/dL (-0.5%), P = 0.016], total [-19.6 mg/dL (-7.3%) vs. -5.3 mg/dL (-1.7%), P = 0.014] and non-high-density lipoprotein cholesterol levels [PA vs. placebo: -18.9 mg/dL (-9.1%) vs. -0.6 mg/dL (-0.5%), P = 0.002] in subjects with elevated baseline LDL cholesterol levels. CONCLUSION: Our findings reveal a novel immune-mediated pathway linking the gut microbiota-derived metabolite PA with intestinal Npc1l1 expression and cholesterol homeostasis. The results highlight the gut immune system as a potential therapeutic target to control dyslipidaemia that may introduce a new avenue for prevention of ACVDs.


Subject(s)
Atherosclerosis , Propionates , Animals , Apolipoproteins E/metabolism , Atherosclerosis/etiology , Cholesterol/metabolism , Cholesterol, LDL/metabolism , Humans , Intestinal Absorption , Mice , Mice, Inbred C57BL , Mice, Knockout , Propionates/pharmacology , Propionates/therapeutic use
3.
Cell Host Microbe ; 29(8): 1249-1265.e9, 2021 Aug 11.
Article in English | MEDLINE | ID: mdl-34289377

ABSTRACT

Early-life antibiotic exposure perturbs the intestinal microbiota and accelerates type 1 diabetes (T1D) development in the NOD mouse model. Here, we found that maternal cecal microbiota transfer (CMT) to NOD mice after early-life antibiotic perturbation largely rescued the induced T1D enhancement. Restoration of the intestinal microbiome was significant and persistent, remediating the antibiotic-depleted diversity, relative abundance of particular taxa, and metabolic pathways. CMT also protected against perturbed metabolites and normalized innate and adaptive immune effectors. CMT restored major patterns of ileal microRNA and histone regulation of gene expression. Further experiments suggest a gut-microbiota-regulated T1D protection mechanism centered on Reg3γ, in an innate intestinal immune network involving CD44, TLR2, and Reg3γ. This regulation affects downstream immunological tone, which may lead to protection against tissue-specific T1D injury.


Subject(s)
Anti-Bacterial Agents/pharmacology , Cecum/immunology , Cecum/microbiology , Diabetes Mellitus, Type 1/immunology , Gastrointestinal Microbiome/drug effects , Gastrointestinal Microbiome/physiology , Animals , Autoimmune Diseases , Bacteria/classification , Bacteria/drug effects , Disease Models, Animal , Female , Gene Expression , Histone Code , Intestines/immunology , Male , Metabolic Networks and Pathways , Metagenome , Mice , Mice, Inbred NOD , MicroRNAs
4.
Gut Microbes ; 13(1): 1946368, 2021.
Article in English | MEDLINE | ID: mdl-34313547

ABSTRACT

Over the past three decades the United States has experienced a devastating opioid epidemic. One of the many debilitating side effects of chronic opioid use is opioid-induced bowel dysfunction. We investigated the impact of methadone maintenance treatment (MMT) on the gut microbiome, the gut bacterial metabolite profile, and intestinal barrier integrity. An imbalance in key bacterial communities required for production of short-chain fatty acids (SCFAs), mucus degradation, and maintenance of barrier integrity was identified. Consistent with dysbiosis, levels of fecal SCFAs were reduced in MMT. We demonstrated that metabolites synthesized by Akkermansia muciniphila modulate intestinal barrier integrity in vitro by strengthening the pore pathway and regulating tight junction protein expression. This study provides essential information about the therapeutic potential of A. muciniphila and warrants development of new clinical strategies that aim to normalize the gut microbiome in individuals affected by chronic opioid use.


Subject(s)
Analgesics, Opioid/adverse effects , Dysbiosis/chemically induced , Dysbiosis/physiopathology , Gastrointestinal Microbiome/drug effects , Methadone/therapeutic use , Opioid-Related Disorders/drug therapy , Opioid-Related Disorders/physiopathology , Adult , Analgesics, Opioid/therapeutic use , Animals , Female , Healthy Volunteers , Humans , Male , Middle Aged , Opioid-Related Disorders/epidemiology , United States
5.
FASEB J ; 33(1): 1098-1109, 2019 01.
Article in English | MEDLINE | ID: mdl-30102568

ABSTRACT

Alterations in gut microbiota are known to affect intestinal inflammation and obesity. Antibiotic treatment can affect weight gain by elimination of histone deacetylase (HDAC) inhibitor-producing microbes, which are anti-inflammatory by augmenting regulatory T (Treg) cells. We asked whether mice that lack HDAC6 and have potent suppressive Treg cells are protected from microbiota-induced accelerated weight gain. We crossed wild-type and HDAC6-deficient mice and subjected the offspring to perinatal penicillin, inducing weight gain via microbiota disturbance. We observed that male HDAC6-deficient mice were not protected and developed profoundly accelerated weight gain. The antibiotic-exposed HDAC6-deficient mice showed a mixed immune phenotype with increased CD4+ and CD8+ T-cell activation yet maintained the enhanced Treg cell-suppressive function phenotype characteristic of HDAC6-deficient mice. 16S rRNA sequencing of mouse fecal samples reveals that their microbiota diverged with time, with HDAC6 deletion altering microbiome composition. On a high-fat diet, HDAC6-deficient mice were depleted in representatives of the S24-7 family and Lactobacillus but enriched with Bacteroides and Parabacteroides; these changes are associated with obesity. Our findings further our understanding of the influence of HDACs on microbiome composition and are important for the development of HDAC6 inhibitors in the treatment of human diseases.-Lieber, A. D., Beier, U. H., Xiao, H., Wilkins, B. J., Jiao, J., Li, X. S., Schugar, R. C., Strauch, C. M., Wang, Z., Brown, J. M., Hazen, S. L., Bokulich, N. A., Ruggles, K. V., Akimova, T., Hancock, W. W., Blaser, M. J. Loss of HDAC6 alters gut microbiota and worsens obesity.


Subject(s)
Gastrointestinal Microbiome , Histone Deacetylase 6/physiology , Obesity/genetics , Obesity/microbiology , Animals , Bacteroides/isolation & purification , Diet, High-Fat , Fatty Liver/genetics , Feces , Germ-Free Life , Histone Deacetylase 6/genetics , Hyperlipidemias/genetics , Lactobacillus/isolation & purification , Male , Mesentery/pathology , Mice , Mice, Inbred C57BL , Mice, Knockout , Obesity/immunology , Spleen/pathology , T-Lymphocytes, Regulatory/immunology , Up-Regulation , Weight Gain
6.
Biores Open Access ; 4(1): 54-64, 2015.
Article in English | MEDLINE | ID: mdl-26309782

ABSTRACT

Advanced glycation end products (AGEs) accumulate in the aging skin. To understand the biological effects of individual AGEs, skin reconstructed with collagen selectively enriched with N(ɛ)-(carboxymethyl)-lysine (CML), N(ɛ)-(carboxyethyl)-lysine (CEL), methylglyoxal hydroimidazolone (MG-H1), or pentosidine was studied. Immunohistochemistry revealed increased expression of α6 integrin at the dermal epidermal junction by CEL and CML (p<0.01). Laminin 5 was diminished by CEL and MG-H1 (p<0.05). Both CML and CEL induced a robust increase (p<0.01) in procollagen I. In the culture medium, IL-6, VEGF, and MMP1 secretion were significantly decreased (p<0.05) by MG-H1. While both CEL and CML decreased MMP3, only CEL decreased IL-6 and TIMP1, while CML stimulated TIMP1 synthesis significantly (p<0.05). mRNA expression studies using qPCR in the epidermis layer showed that CEL increased type 7 collagen (COL7A1), ß1, and α6 integrin, while CML increased only COL7A1 (p<0.05). MG-H1-modified collagen had no effect. Importantly, in the dermis layer, MMP3 mRNA expression was increased by both CML and MG-H1. CML also significantly increased the mRNAs of MMP1, TIMP1, keratinocyte growth factor (KGF), IL-6, and monocyte chemoattractant protein 1 (MCP1) (p<0.05). Mixed effects were present in CEL-rich matrix. Minimally glycoxidized pentosidine-rich collagen suppressed most mRNAs of the genes studied (p<0.05) and decreased VEGF and increased MCP1 protein expression. Taken together, this model of the aging skin suggests that a combination of AGEs tends to counterbalance and thus minimizes the detrimental biological effects of individual AGEs.

7.
Diab Vasc Dis Res ; 11(2): 84-91, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24443481

ABSTRACT

Our aims were to study left ventricular (LV) function and myocardial blood flow reserve (MBFR) in long-term type 1 diabetes and associations with advanced glycation end products (AGEs). A total of 20 type 1 diabetes patients from the Oslo Study without significant stenosis on coronary angiography were compared with 26 controls. LV systolic and diastolic functions were assessed by two-dimensional strain and the ratio between pulsed Doppler transmitral early (E) velocity and tissue Doppler velocity (E'), respectively. MBFR was evaluated by contrast echocardiography. The AGE methylglyoxal-derived hydroimidazolone was analysed in serum. Glyoxal hydroimidazolone in skin collagen was determined by liquid chromatography-mass spectrometry. Strain was significantly reduced (-19.5% ± 1.9% vs -21.4% ± 3.5%, p < 0.05), and E/E' increased in the diabetes patients compared to controls, 7.3 ± 2 versus 6.0 ± 1.5, p < 0.05. Significant lower MBFR was present in the diabetes patients, 3.4 (2.1, 5.3) versus 5.9 (3.9, 9.6), p < 0.01. Both AGEs correlated significantly with E/E'. The impaired LV function with correlation to AGEs in concert with reduced MBFR in diabetics without coronary artery disease may indicate possible mechanisms for diabetic cardiomyopathy.


Subject(s)
Coronary Artery Disease/physiopathology , Diabetes Mellitus, Type 1/metabolism , Ventricular Dysfunction, Left/physiopathology , Adult , Aged , Coronary Artery Disease/complications , Coronary Artery Disease/diagnostic imaging , Diabetes Mellitus, Type 1/complications , Diabetes Mellitus, Type 1/diagnostic imaging , Echocardiography, Doppler/methods , Female , Glycation End Products, Advanced/metabolism , Humans , Male , Middle Aged , Time , Ventricular Dysfunction, Left/complications , Ventricular Dysfunction, Left/diagnostic imaging
8.
Mol Vis ; 17: 2221-7, 2011.
Article in English | MEDLINE | ID: mdl-21897744

ABSTRACT

PURPOSE: Previous experiments from our laboratory showed that the oral intake of selected guanidino compounds could block the formation of crystallin-bound advanced ascorbylation products. Here we tested whether these were also active when applied as eye drops. METHODS: Two month old hSVCT2 transgenic mice (n=10) were treated twice daily with one drop of 0.1% L-arginine, γ-guanidinobutyric acid (GBA), penicillamine (PA) or N-acetylcysteine (NAC) in one eye and vehicle only in the other eye. After seven months, lens crystallins were isolated, dialyzed, and proteolytically digested to determine the protein-bound fluorescence at 335/385 and 370/440 nm excitation/emission and the advanced glycation/ascorbylation endproducts carboxymethyl-lysine (CML), carboxyethyl-lysine (CEL), glucosepane, glyoxal, and methylglyoxal hydroimidazolones G-H1 and MG-H1. The topical uptake of L-arginine and NAC was also evaluated in vitro and in vivo in rabbit lens. RESULTS: In hSVCT2 mice, L-arginine decreased 335/385 and 370/440 nm fluorescence by 40% (p<0.001), CML, CEL, and glucosepane crystallin crosslinks by 35% (p<0.05), 30% (p<0.05), and 37% (p<0.05), respectively, without affecting MG-H1 and G-H1. NAC decreased 335/385 nm fluorescence by 50% (p<0.001) but, like PA and GBA, had no effect on other modifications. L-Arginine uptake into rabbit eyes treated topically reached identical lenticular plateau levels (~400 nmol/g wet weight) at 0.5% and 2.0% but levels remained three times higher at 5 h at 2% versus 0.5% concentration, respectively. In vitro studies showed a 100 fold higher L-arginine level than NAC levels, implicating high affinity uptake of the former. CONCLUSIONS: L-Arginine when applied both orally and topically is a potent and broad suppressor of advanced ascorbylation in the lens. Its uptake in rabbit lens upon topical application suggests transcorneal uptake into the human lens should be feasible for testing its potential anticataract properties in clinical trials.


Subject(s)
Arginine , Ascorbic Acid/metabolism , Cataract/prevention & control , Crystallins/metabolism , Glycation End Products, Advanced/metabolism , Lens, Crystalline , Sodium-Coupled Vitamin C Transporters/metabolism , Acetylcysteine/administration & dosage , Administration, Topical , Aging , Animals , Arginine/administration & dosage , Arginine/therapeutic use , Biological Transport, Active , Gene Knock-In Techniques , Guanidines/administration & dosage , Humans , Lens, Crystalline/drug effects , Lens, Crystalline/metabolism , Lens, Crystalline/pathology , Mass Spectrometry , Mice , Mice, Transgenic , Ophthalmic Solutions/administration & dosage , Penicillamine/administration & dosage , Rabbits , Sodium-Coupled Vitamin C Transporters/genetics , Spectrometry, Fluorescence
9.
Diabetes Care ; 34(4): 968-74, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21447665

ABSTRACT

OBJECTIVE: To assess complication prevalence and identify protective factors in patients with diabetes duration of ≥50 years. Characterization of a complication-free subgroup in this cohort would suggest that some individuals are protected from diabetes complications and allow identification of endogenous protective factors. RESEARCH DESIGN AND METHODS: Cross-sectional, observational study of 351 U.S. residents who have survived with type 1 diabetes for ≥50 years (Medalists). Retinopathy, nephropathy, neuropathy, and cardiovascular disease were assessed in relation to HbA(1c), lipids, and advanced glycation end products (AGEs). Retrospective chart review provided longitudinal ophthalmic data for a subgroup. RESULTS: A high proportion of Medalists remain free from proliferative diabetic retinopathy (PDR) (42.6%), nephropathy (86.9%), neuropathy (39.4%), or cardiovascular disease (51.5%). Current and longitudinal (the past 15 years) glycemic control were unrelated to complications. Subjects with high plasma carboxyethyl-lysine and pentosidine were 7.2-fold more likely to have any complication. Of Medalists without PDR, 96% with no retinopathy progression over the first 17 years of follow-up did not experience retinopathy worsening thereafter. CONCLUSIONS: The Medalist population is likely enriched for protective factors against complications. These factors might prove useful to the general population with diabetes if they can be used to induce protection against long-term complications. Specific AGE combinations were strongly associated with complications, indicating a link between AGE formation or processing with development of diabetic vasculopathy.


Subject(s)
Diabetes Mellitus, Type 1/blood , Diabetes Mellitus, Type 1/complications , Diabetic Retinopathy/blood , Aged , Arginine/analogs & derivatives , Arginine/blood , Cross-Sectional Studies , Diabetic Nephropathies/blood , Female , Humans , Lysine/analogs & derivatives , Lysine/blood , Male , Middle Aged
10.
Amino Acids ; 40(1): 167-81, 2011 Jan.
Article in English | MEDLINE | ID: mdl-20607325

ABSTRACT

We describe the isolation and molecular characterization of a novel glucose-lysine dimer crosslink 1,3-bis-(5-amino-5-carboxypentyl)-4-(1',2',3',4'-tetrahydroxybutyl)-3H-imidazolium salt, named GLUCOLD. GLUCOLD was easily formed from the Amadori product (fructose-lysine). However, when BSA was incubated with 100 mM glucose for 25 days, the levels of the lysine-lysine glucose crosslinks GLUCOLD and CROSSLINE were only 21 and <1 pmol/mg, respectively, compared to 611 pmol/mg protein for the lysine-arginine GLUCOSEPANE crosslink, in spite of more than 20 potential lysine-lysine crosslinking sites in the protein. Mechanistic investigation revealed that metal-free phosphate ions catalyzed formation of fructose-lysine and all three crosslinks from amino acids, while cationic MOPS buffer had an opposite effect. This together with the rapid formation of N (6)-1,4-dideoxy-5,6-dioxoglucosone derivatives by dicarbonyl trapping agents, such as 1,2-diaminobenzene or γ-guanidinobutyric acid, strongly suggests that enolization of the Amadori product and trapping of the 5,6-dioxo derivative by arginine residues constitutes the major pathway for glucose-mediated crosslinking in proteins.


Subject(s)
Glucose/chemistry , Glycation End Products, Advanced/chemistry , Lysine/chemistry , Proteins/chemistry , Cross-Linking Reagents/chemistry , Maillard Reaction
11.
Ann N Y Acad Sci ; 1126: 205-9, 2008 Apr.
Article in English | MEDLINE | ID: mdl-18448817

ABSTRACT

The epsilon-amino group of lysyl residues oxidatively deaminates in the presence of alpha-dicarbonyl sugars and redox-active metals forming alpha-aminoadipic acid-delta-semialdehyde (allysine; Suyama's hypothesis), which can further oxidize into 2-aminoadipic acid. Here we show that 2-aminoadipic acid is significantly (P < 0.05) correlated with 6-hydroxynorleucine, carboxyethyllysine (CEL), and carboxymethyllysine (CML) in human skin collagen. Since CEL and CML can originate from carbohydrate and lipid by oxidative decomposition and alpha-dicarbonyl formation, these results provide support for Suyama's hypothesis. Allysine, in turn, is readily converted by oxidation into 2-aminoadipic acid, which accumulates to high levels in skin (i.e., > 2 nmol/mg collagen).


Subject(s)
2-Aminoadipic Acid/metabolism , Aging/physiology , Collagen/metabolism , Diabetes Mellitus/physiopathology , Diabetic Nephropathies/physiopathology , Skin Aging , Skin/metabolism , Adolescent , Adult , Child , Child, Preschool , Humans , Infant , Infant, Newborn , Lysine/metabolism , Middle Aged , Oxidation-Reduction
12.
Biochem J ; 404(2): 269-77, 2007 Jun 01.
Article in English | MEDLINE | ID: mdl-17313367

ABSTRACT

We hypothesized that the epsilon-amino group of lysine residues in longlived proteins oxidatively deaminates with age forming the carbonyl compound, allysine (alpha-aminoadipic acid-delta-semialdehyde), which can further oxidize into 2-aminoadipic acid. In the present study, we measured both products in insoluble human skin collagen from n=117 individuals of age range 10-90 years, of which n=61 and n=56 were non-diabetic and diabetic respectively, and a total of n=61 individuals had either acute or chronic renal failure. Allysine was reduced by borohydride into 6-hydroxynorleucine and both products were measured in acid hydrolysates by selective ion monitoring gas chromatography (GC)-MS. The results showed that 2-aminoadipic acid (P<0.0001), but not 6-hydroxynorleucine (P=0.14), significantly increased with age reaching levels of 1 and 0.3 mmol/mol lysine at late age respectively. Diabetes in the absence of renal failure significantly (P<0.0001) increased 2-aminoadipic acid up to <3 mmol/mol, but not 6-hydroxynorleucine (levels<0.4 mmol/mol, P=0.18). Renal failure even in the absence of diabetes markedly increased levels reaching up to <0.5 and 8 mmol/mol for 6-hydroxynorleucine and 2-aminoadipic acid respectively. Septicaemia significantly (P<0.0001) elevated 2-aminoadipic acid in non-diabetic, but not diabetic individuals, and mildly correlated with other glycoxidation markers, carboxymethyl-lysine and the methylglyoxal-derived products, carboxyethyl-lysine, argpyrimidine and MODIC (methylglyoxal-derived imidazolium cross-link). These results provide support for the presence of metal-catalysed oxidation (the Suyama pathway) in diabetes and the possible activation of myeloperoxidase during sepsis. We conclude that 2-aminoadipic acid is a more reliable marker for protein oxidation than its precursor, allysine. Its mechanism of formation in each of these conditions needs to be elucidated.


Subject(s)
2-Aminoadipic Acid/metabolism , Aging/metabolism , Biomarkers/metabolism , Diabetes Mellitus/metabolism , Proteins/metabolism , Renal Insufficiency/metabolism , Sepsis/metabolism , Skin/metabolism , Adolescent , Adult , Aged , Aged, 80 and over , Child , Collagen/metabolism , Female , Humans , Male , Middle Aged , Oxidation-Reduction , Skin Aging
13.
J Biol Chem ; 280(13): 12310-5, 2005 Apr 01.
Article in English | MEDLINE | ID: mdl-15677467

ABSTRACT

The extracellular matrix in most tissues is characterized by progressive age-related stiffening and loss of proteolytic digestibility that are accelerated in diabetes and can be duplicated by the nonenzymatic reaction of reducing sugars and extracellular matrix proteins. However, most cross-links of the Maillard reaction described so far are present in quantities too low to account for these changes. Here we have determined in human skin and glomerular basement membrane (GBM) collagen the levels of the recently discovered lysine-arginine cross-links derived from glucose, methylglyoxal, glyoxal, and 3-deoxyglucosone, i.e. glucosepane, MODIC, GODIC, and DOGDIC, respectively. Insoluble preparations of skin collagen (n = 110) and glomerular basement membrane (GBM, n = 28) were enzymatically digested, and levels were measured by isotope dilution technique using liquid chromatography/mass spectrometry. In skin, all cross-links increased with age (p < 0.0001) except DOGDIC (p = 0.34). In nondiabetic controls, levels at 90 years were 2000, 30, and 15 pmol/mg for glucosepane, MODIC, and GODIC, respectively. Diabetes, but not renal failure, increased glucosepane to 5000 pmol/mg (p < 0.0001), and for all others, increased it to <60 pmol/mg (p < 0.01). In GBMs, glucosepane reached up to 500 pmol/mg of collagen and was increased in diabetes (p < 0.0001) but not old age. In conclusion, glucosepane is the single major cross-link of the senescent extracellular matrix discovered so far, accounting for up to >120 mole% of triple helical collagen modification in diabetes. Its presence in high quantities may contribute to a number of structural and cell matrix dysfunctions observed in aging and diabetes.


Subject(s)
Azepines/chemistry , Azepines/metabolism , Collagen/metabolism , Diabetes Mellitus, Type 2/metabolism , Extracellular Matrix/metabolism , Lysine/analogs & derivatives , Lysine/chemistry , Lysine/metabolism , Skin/metabolism , Adolescent , Adult , Age Factors , Aged , Aged, 80 and over , Arginine/chemistry , Basement Membrane/metabolism , Cellular Senescence , Chromatography, High Pressure Liquid , Collagen/chemistry , Cross-Linking Reagents/pharmacology , Female , Humans , Imidazoles/metabolism , Kidney Failure, Chronic/metabolism , Kidney Glomerulus/metabolism , Male , Middle Aged , Models, Chemical , Protein Binding , Regression Analysis , Renal Insufficiency/metabolism , Time Factors
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