CML Levels Research Articles

Early- and life-long intake of dietary advanced glycation end-products (dAGEs) leads to transient tissue accumulation, increased gut sensitivity to inflammation, and slight changes in gut microbial diversity, without causing overt disease

Dietary advanced glycation end-products (dAGEs) accumulate in organs and are thought to initiate chronic low-grade inflammation (CLGI), induce glycoxidative stress, drive immunosenescence, and influence gut microbiota. Part of the toxicological interest in glycation products such as dietary carboxymethyl-lysine (dCML) relies on their interaction with receptor for advanced glycation end-products (RAGE). It remains uncertain whether early or lifelong exposure to dAGEs contributes physiological changes and whether such effects are reversible or permanent. Our objective was to examine the physiological changes in Wild-Type (WT) and RAGE KO mice that were fed either a standard diet (STD − 20.8 ± 5.1 µg dCML/g) or a diet enriched with dCML (255.2 ± 44.5 µg dCML/g) from the perinatal period for up to 70 weeks. Additionally, an early age (6 weeks) diet switch (dCML→STD) was explored to determine whether potential harmful effects of dCML could be reversed. Previous dCML accumulation patterns described by our group were confirmed here, with significant RAGE-independent accumulation of dCML in kidneys, ileum and colon over the 70-week dietary intervention (respectively 3-fold, 17-fold and 20-fold increases compared with controls). Diet switching returned tissue dCML concentrations to their baseline levels. The dCML-enriched diet had no significative effect on endogenous glycation, inflammation, oxidative stress or senescence parameters. The relative expression of TNFα, VCAM1, IL6, and P16 genes were all upregulated (∼2-fold) in an age-dependent manner, most notably in the kidneys of WT animals. RAGE knockout seemed protective in this regard, diminishing age-related renal expression of TNFα. Significant increases in TNFα expression were detectable in the intestinal tract of the Switch group (∼2-fold), suggesting a higher sensitivity to inflammation perhaps related to the timing of the diet change. Minor fluctuations were observed at family level within the caecal microbiota, including Eggerthellaceae, Anaerovoracaceae and Marinifilaceae communities, indicating slight changes in composition. Despite chronic dCML consumption resulting in higher free CML levels in tissues, there were no substantial increases in parameters related to inflammageing. Age was a more important factor in inflammation status, notably in the kidneys, while the early-life dietary switch may have influenced intestinal susceptibility to inflammation. This study affirms the therapeutic potential of RAGE modulation and corroborates evidence for the disruptive effect of dietary changes occurring too early in life. Future research should prioritize the potential influence of dAGEs on disease aetiology and development, notably any exacerbating effects they may have upon existing health conditions.

Comparative Physiological and Transcriptomic Analyses of Oat (Avena sativa) Seedlings under Salt Stress Reveal Salt Tolerance Mechanisms.

Soil salinity is a major abiotic stress limiting crop production globally. Oat (Avena sativa) is an annual cereal with a strong salt tolerance, a high yield, and nutritional quality, although the mechanisms underlying its salt stress response remain largely unknown. We examined the physiological and transcriptomic responses of A. sativa seedlings to salt stress in tolerant cultivar Qingyongjiu 195 and sensitive cultivar 709. Under salt stress, Qingyongjiu 195 maintained a higher photosynthetic efficiency, antioxidant enzymes activity, and leaf K+ accumulation but a lower Na+ uptake than 709. RNA-seq revealed 6616 differentially expressed genes (DEGs), including 4265 up- and 2351 downregulated. These were enriched in pathways like plant-pathogen interaction, phenylpropanoid biosynthesis, and MAPK signaling. We specifically highlight DEGs involved in photosynthesis (chlG, CP47 psbB, COX2, LHCB) and antioxidants (trxA, GroES). Qingyongjiu 195 also appeared to enhance K+ uptake via KAT1 and AKT2 and sequester Na+ in vacuoles via NHX2. Additionally, HKT restricted Na+ while promoting K+ transport to shoots, maintaining K+/Na+. The expression levels of CAX, ACA, CML, CaM, and CDPK in Qingyongjiu 195 were higher than those in 709. Oats regulated Ca2+ concentration through CAX and ACA after salt stress, decoded Ca2+ signals through CML, and then transferred Ca2+ signals to downstream receptors through the Ca2+ sensors CaM and CDPK, thereby activating K+/Na+ transporters, such as SOS1 and NHX, etc. Our results shed light on plant salt stress response mechanisms and provide transcriptomic resources for molecular breeding in improving salt tolerance in oats.

Placental Methylglyoxal in Preeclampsia: Vascular and Biomarker Implications.

Preeclampsia is a multifaceted syndrome that includes maternal vascular dysfunction. We hypothesize that increased placental glycolysis and hypoxia in preeclampsia lead to increased levels of methylglyoxal (MGO), consequently causing vascular dysfunction. Plasma samples and placentas were collected from uncomplicated and preeclampsia pregnancies. Uncomplicated placentas and trophoblast cells (BeWo) were exposed to hypoxia. The reactive dicarbonyl MGO and advanced glycation end products (Nε-(carboxymethyl)lysine [CML], Nε-(carboxyethyl)lysine [CEL], and MGO-derived hydroimidazolone [MG-H]) were quantified using liquid chromatography-tandem mass spectrometry. The activity of GLO1 (glyoxalase-1), that is, the enzyme detoxifying MGO, was measured. The impact of MGO on vascular function was evaluated using wire/pressure myography. The therapeutic potential of the MGO-quencher quercetin and mitochondrial-specific antioxidant mitoquinone mesylate (MitoQ) was explored. MGO, CML, CEL, and MG-H2 levels were elevated in preeclampsia-placentas (+36%, +36%, +25%, and +22%, respectively). Reduced GLO1 activity was observed in preeclampsia-placentas (-12%) and hypoxia-exposed placentas (-16%). Hypoxia-induced MGO accumulation in placentas was mitigated by the MGO-quencher quercetin. Trophoblast cells were identified as the primary source of MGO. Reduced GLO1 activity was also observed in hypoxia-exposed BeWo cells (-26%). Maternal plasma concentrations of CML and the MGO-derived MG-H1 increased as early as 12 weeks of gestation (+16% and +17%, respectively). MGO impaired endothelial barrier function, an effect mitigated by MitoQ, and heightened vascular responsiveness to thromboxane A2. This study reveals the accumulation of placental MGO in preeclampsia and upon exposure to hypoxia, demonstrates how MGO can contribute to vascular impairment, and highlights plasma CML and MG-H1 levels as promising early biomarkers for preeclampsia.

Nε-carboxymethyl-lysine and inflammatory cytokines, markers and mediators of coronary artery disease progression in diabetes

This editorial refers to the article “Comparative analysis of Nε-carboxymethyl-lysine and inflammatory markers in diabetic and non-diabetic coronary artery disease patients”, published in the recent issue of the World Journal of Diabetes 2023 is based on glucose metabolism, advanced glycation end products (AGEs), inflammation and adiposity on diabetes and coronary artery disease (CAD). This study has included CAD patients who were stratified according to glycosylated hemoglobin higher than 6.5 and sex-matched. A higher prevalence of hypertension, dyslipidemia, and non-vegetarian diet were found in the diabetic group. These risk factors might influence body weight and adiposity and explain the increment of the left atrium. Although this data was not supported by the study. The diet can also explain the non-enzymatic reactions on lipids, proteins, or nucleic acids and consequently an increment of AGEs. These molecules can emit fluorescence. However, one of the non-fluorescent and most abundant AGEs is Nε-carboxymethyl-lysine (CML). Its association with coronary artery stenosis and severity in the diabetic group might suggest its role as a player in CAD progression. Thus, CML, after binding with its receptor (RAGE), can induce calcification cascade through reactive oxygen species and mitogen-activated protein kinase. Moreover, this interaction AGE-RAGE can cause activation of the transcription nuclear factor-kb and induce inflammatory cytokines. It might explain the relationship between CML and pro-inflammatory cytokines in diabetic and CAD patients. Although this is a population from one center, the determination of CML and inflammatory cytokines might improve the diagnosis of severe and progressive CAD. Future and comparative studies among glycosylated hemoglobin, CML, and other AGE levels according to diagnosis and prognosis value might modify the clinical practice. Although these molecules are irreversible, they can act through a specific receptor inducing a signal transduction that might be modu-lated by inhibitors, antibodies, or siRNA. Further mechanistic studies might improve the development of future preventive therapies for diabetic patients.

Correlation of mild cognitive impairment with the thickness of retinal nerve fiber layer and serum indicators in type 2 diabetic patients.

Cognitive Impairment arising from type 2 diabetes mellitus (T2DM) has garnered significant attention in recent times. However, there are few studies on the identification and diagnosis of markers of cognitive impairment. Notably, alterations in the Retinal Nerve Fiber Layer's (RNFL) thickness can potentially serve as an indicative measure of central nervous system changes. Further investigations have indicated that the decline in cognitive function within T2DM patients is intricately linked to persistent systemic inflammation and the accumulation of advanced glycosylation end products. Comprehensive studies are warranted to unveil these complex associations. This study aims to explore the potential of utilizing the RNFL thickness and serological concentrations of IL-18, irisin, CML, and RAGE as diagnostic indicators for Mild Cognitive Impairment (MCI) among individuals with T2DM. The thickness of RNFL were determined in all patients and controls using optical coherence tomography (OCT). The serum levels of IL-18, irisin, CML and RAGE were detected by ELISA kit. In addition, Cognitive assessment was performed by the Mini-Mental State Examination (MMSE) and the Montreal Cognitive assessment (MoCA). The average RNFL thickness in the right eye were decreased in T2DM and T2DM combined with MCI (T2DM-MCI) patients and were positively correlated with MoCA and MMSE scores. The serum levels of IL-18, CML and RAGE in T2DM and T2DM-MCI increased significantly (p<0.05) and were negative correlated with MoCA and MMSE scores. The level of irisin in T2DM and T2DM-MCI decreased significantly (p<0.05) and were positively correlated with MoCA and MMSE scores. The area under the ROC curve of T2DM-MCI predicted by the average RNFL thickness in the right eye, CML and RAGE were 0.853, 0.874 and 0.815. The diagnostic efficacy of the combination of average RNFL thickness in the right eye, CML, and RAGE for the diagnosis of T2DM-MCI was 0.969. The average RNFL thickness in the right eye, CML and RAGE have possible diagnostic value in T2DM-MCI patients.

Comparative analysis of Nε-carboxymethyl-lysine and inflammatory markers in diabetic and non-diabetic coronary artery disease patients.

Coronary artery disease (CAD) is a major cause of death worldwide, and India contributes to about one-fifth of total CAD deaths. The development of CAD has been linked to the accumulation of Nε-carboxymethyl-lysine (CML) in heart muscle, which correlates with fibrosis. To assess the impact of CML and inflammatory markers on the biochemical and cardiovascular characteristics of CAD patients with and without diabetes. We enrolled 200 consecutive CAD patients who were undergoing coronary angiography and categorized them into two groups based on their serum glycosylated hemoglobin (HbA1c) levels (group I: HbA1c ≥ 6.5; group II: HbA1c < 6.5). We analyzed the levels of lipoproteins, plasma HbA1c levels, CML, interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and nitric oxide. Group I (81 males and 19 females) patients had a mean age of 54.2 ± 10.2 years, with a mean diabetes duration of 4.9 ± 2.2 years. Group II (89 males and 11 females) patients had a mean age of 53.2 ± 10.3 years. Group I had more severe CAD, with a higher percentage of patients with single vessel disease and greater stenosis severity in the left anterior descending coronary artery compared to group II. Group I also exhibited a larger left atrium diameter. Group I patients exhibited significantly higher levels of CML, TNF-α, and IL-6 and lower levels of nitric oxide as compared with group II patients. Additionally, CML showed a significant positive correlation with IL-6 (r = 0.596, P = 0.001) and TNF-α (r = 0.337, P = 0.001) and a negative correlation with nitric oxide (r=-4.16, P = 0.001). Odds ratio analysis revealed that patients with CML in the third quartile (264.43-364.31 ng/mL) were significantly associated with diabetic CAD at unadjusted and adjusted levels with covariates. CML and inflammatory markers may play a significant role in the development of CAD, particularly in diabetic individuals, and may serve as potential biomarkers for the prediction of CAD in both diabetic and non-diabetic patients.

Processing Stage-Induced Formation of Advanced Glycation End Products in Cooked Sausages with the Addition of Spices.

This study aims to evaluate the relationship between the four processing stages of cooked sausage preparation (raw, drying, baking, and steaming) and the formation of advanced glycation end products (AGEs), 1,2-dicarbonyl compounds, and lipid and protein oxidation in sausages with spices. Baking and steaming significantly promoted lipid and protein oxidation. The Nε-carboxymethyllysine (CML) content increased from 4.32-4.81 µg/g in raw samples to 10.68-16.20 µg/g in the steamed sausages. Nε-carboxyethyllysine (CEL) concentrations increased by approximately 1.7-3.7 times after steaming. The methylglyoxal concentration increased dramatically after baking and then rapidly decreased in the steaming stage. Chili promoted the formation of CML and CEL. The CEL concentration increased in samples containing garlic, but yellow mustard and garlic slightly reduced CML concentrations in the cooked sausages. The spices decreased the lipid and protein stability of the cooked sausages, increasing malondialdehyde and protein carbonyls. Lipid oxidation and 3-deoxyglucosone positively correlated with CML and CEL levels. Black pepper had no impact on CML when the sausages were baked but remarkably increased the content of both CML and CEL in the steaming stage. Thus, the impact of spices on sausages depends on both the specific spices used and the category of AGEs formed.

Isotope dilution-HPLC-MS/MS to investigate the production patterns and possible pathways of free and protein-bound AGEs and 4-MI in cookies

A qualitative and quantitative method for detecting free and protein-bound advanced glycation end products (AGEs) and 4-methylimidazole (4-MI) was established using isotope dilution-HPLC-MS/MS, and successfully applied in cookies and model systems. The effects of different temperatures (160–220 °C) on the formation of free and protein-bound AGEs and 4-MI in cookies were discussed, and the possible model systems (Maillard reaction pathway 1 using wheat gluten protein + glucose + sucrose; direct addition pathway 1 using wheat gluten protein + CML/CEL/4-MI) of protein-bound AGEs and 4-MI were verified. The results showed that the contents of protein-bound CML, CEL, and 4-MI were higher than free content with a tendency of increasing first and subsequently decreasing with temperature, reaching a maximum at 200 °C in cookies. In the model systems, the levels of protein-bound CML, CEL, and 4-MI are higher than those of free CML, CEL, and 4-MI. The protein-bound CML, CEL, and 4-MI accounted for 90.73, 87.64, and 97.56% of the total amount in the model system 1, while accounting for 68.19, 59.00, and 50.96% in the model system 2, respectively. In comparison, protein-bound CML, CEL, and 4-MI could be easily generated directly by Maillard reaction.

SIRT3-and FAK-mediated acetylation-phosphorylation crosstalk of NFATc1 regulates Nε-carboxymethyl-lysine-induced vascular calcification in diabetes mellitus

Background and aimsArterial calcification is the predictor of cardiovascular risk in diabetic patients. Nε-carboxymethyl-lysine (CML), a toxic metabolite, is associated with accelerated vascular calcification in diabetes mellitus (DM). However, the mechanism remains elusive. This study aims to explore the key regulators involved in CML-induced vascular calcification in DM. MethodsWe used Western blot and immuno-staining to test the expression and localization of nuclear factor of activated T cells, cytoplasmic 1 (NFATc1) in human samples, a diabetic apolipoprotein E-deficient (ApoE−/−) mouse model, and a vascular smooth muscle cells (VSMC) model. Further, we confirmed the regulator of NFATc1 phosphorylation and acetylation induced by CML. The role of NFATc1 in VSMCs calcification and osteogenic differentiation was explored in vivo and in vitro. ResultsIn diabetic patients, CML and NFATc1 levels increased in the severe calcified anterior tibial arteries. CML significantly promoted NFATc1 expression and nuclear translocation in VSMCs and mouse aorta. Knockdown of NFATc1 significantly inhibited CML-induced calcification. CML promoted NFATc1 acetylation at K549 by downregulating sirtuin 3 (SIRT3), which antagonized the focal adhesion kinase (FAK) induced NFATc1 phosphorylation at the Y270 site. FAK and SIRT3 affected the nuclear translocation of NFATc1 by regulating the acetylation-phosphorylation crosstalk. NFATc1 dephosphorylation mutant Y270F and deacetylation mutant K549R had opposite effects on VSMC calcification. SIRT3 overexpression and FAK inhibitor could reverse CML-promoted VSMC calcification. ConclusionsCML enhances vascular calcification in DM through NFATc1. In this process, CML increases NFATc1 acetylation by downregulating SIRT3 to antagonize FAK-induced NFATc1 phosphorylation.

Nε-(1-Carboxymethyl)-L-lysine, an advanced glycation end product, exerts malignancy on chondrosarcoma via the activation of cancer stemness.

Despite epidemiological evidence that suggests diabetes mellitus is a risk factor for cancer, the link between diabetes mellitus and primary bone cancer is rarely discussed. Chondrosarcomas are primary malignant cartilage tumors with poor prognosis and high metastatic potential. It remains unclear whether hyperglycemia affects the stemness and malignancy of chondrosarcoma cells. Nε-(1-Carboxymethyl)-L-lysine (CML), an advanced glycation end product (AGE), is a major immunological epitope detected in the tissue proteins of diabetic patients. We hypothesized that CML could enhance cancer stemness in chondrosarcoma cells. CML enhanced tumor-sphere formation and the expression of cancer stem cell markers in human chondrosarcoma cell lines. Migration and invasion ability and the epithelial-mesenchymal transition (EMT) process were also induced by CML treatment. Moreover, CML increased the protein expression levels of the receptor for AGE (RAGE), phosphorylated NFκB-p65, and decreased the phosphorylation of AKT and GSK-3. We also found that hyperglycemia with high CML levels facilitated tumor metastasis, whereas tumor growth was not affected in the streptozotocin (STZ)-induced diabetic NOD/SCID tumor xenograft mouse models. Our results indicate that CML enhances chondrosarcoma stemness and metastasis, which may reveal the relationship between AGE and bone cancer metastasis.

Fenugreek seed ethanolic extract inhibited formation of advanced glycation end products via scavenging reactive carbonyl intermediates

Senescence is a natural phenomenon of growing old. It accelerates under certain conditions like diabetes mellitus resulting in early decline of bodily functions, which can be avoided by many claimed functional foods. The present study aims to investigate the anti-aging ability of Fenugreek seeds (Trigonellafoenum-graecum); a common ingredient of Indo-Pak cuisines. Briefly, the Fenugreek seeds extract (FgSE) in concentrationsof0.1, 0.5 and 1 mg/ml inhibited the formation of Advanced Glycation End products (AGEs) and fructosamine adducts in Bovine serum albumin (BSA)/fructose model in vitro. The BSA conformational analysis via Circular Dichorism and Congo red assays showed that it preserves secondary structure of BSA in aforementioned model. Although mechanistic studies revealed insignificant lysine blocking ability of Fenugreek by OPA assay, however carbonyl entrapping was found to be 24%, 34% and 42% at 0.1, 0.5 and 1 mg/ml, respectively. In vivo model of High Fructose diet (HFD) induced glycation, FgSE treatment in doses of 10, 25 & 50 mg/kg markedly improved Escape latency (p < 0.01) and preserved cognition in Morris Water Maze. Our data further exhibits significant decrease of CML (Nε-carboxymethyl lysine) levels in serum and hippocampus byFgSE treatment in comparison with HFD group. Therefore, we deduced that FgSE prevents glycation-induced memory decline via entrapping the reactive carbonyl intermediates, formed during production of AGEs. Hence, as a promising functional food it slows down the harmful process of glycation and aging associated morbidities.

Application of tea polyphenols as additives in brown fermented milk: Potential analysis of mitigating Maillard reaction products

Brown fermented milk (BFM) is favored by consumers in the dairy market for its unique burnt flavor and brown color. However, Maillard reaction products (MRP) from high-temperature baking are also noteworthy. In this study, tea polyphenols (TP) were initially developed as potential inhibitors of MRP formation in BFM. The results showed that the flavor profile of BFM did not change after adding 0.08% (wt/wt) of TP, and its inhibition rates on 5-hydroxymethyl-2-furaldehyde (5-HMF), glyoxal (GO), methylglyoxal (MGO), Nε-carboxymethyl lysine (CML), and Nε-carboxyethyl lysine (CEL) were 60.8%, 27.12%, 23.44%, 57.7%, and 31.28%, respectively. After 21 d of storage, the levels of 5-HMF, GO, MGO, CML, and CEL in BFM with TP were 46.3%, 9.7%, 20.6%, 5.2%, and 24.7% lower than the control group, respectively. Moreover, a smaller change occurred in their color and the browning index was lower than that of the control group. The significance of this study was to develop TP as additives to inhibit the production of MRP in brown fermented yogurt without changing color and flavors, thereby making dairy products safer for consumers.

Are dietary and serum advanced glycation end-products related to inflammation and oxidation biomarkers in breast cancer patients: a follow-up study.

This study is aimed at evaluating the relationship between dietary and serum advanced glycation end-products (AGEs) with serum inflammatory and oxidative stress biomarkers in breast cancer (BC). A sample of BC patients was followed for 12 months (March 2020-January 2022). Three-day food consumption record and serum samples were taken before surgery (T1), before chemotherapy (T2), at the 6th month of chemotherapy (T3), and at the 12th month of chemotherapy (T4). Dietary AGE intake was represented by carboxymethyl lysine (dCML). Serum levels of CML, inflammation, and oxidation biomarkers were determined with biochemical blood tests. The results were compared according to human epidermal growth factor receptor-2 (HER2) status. Thirty-two women with BC and 32 age and body mass index-matched healthy women participated. No significant correlation was found between dCML and serum CML, inflammatory or oxidative stress biomarkers at T1, T2, and T4. A weak positive correlation was demonstrated between dCML and serum malondialdehyde levels (rho=0.355, p=0.046) at T3. The serum CML, inflammation, and oxidation biomarker levels of the HER2- group were significantly higher than those of the HER2+ group at T1. This study suggests that there is limited correlation between dCML and serum inflammation and oxidative stress biomarkers in BC patients. Inflammation and oxidative biomarker levels appear to decline with treatment although dietary and serum AGE levels show not a corresponding significant decline. The HER2- subtype appears to be associated with higher dietary and serum AGEs and higher inflammatory and oxidative stress biomarkers.

Effects of Different Donor Ages on the Growth of Cutting Seedlings Propagated from Ancient Platycladus orientalis.

The effects of tree age on the growth of cutting seedlings propagated from ancient trees have been an important issue in plant breeding and cultivation. In order to understand seedling growth and stress resistance stability, phenotypic measurements, physiological assays, and high-throughput transcriptome sequencing were performed on sown seedlings propagated from 5-year-old donors and cutting seedlings propagated from 5-, 300-, and 700-year-old Platycladus orientalis donors. In this study, the growth of cutting seedlings propagated from ancient trees was significantly slower; the soluble sugar and chlorophyll contents gradually decreased with the increase in the age of donors, and the flavonoid and total phenolic contents of sown seedlings were higher than those of cutting seedlings. Enrichment analysis of differential genes showed that plant hormone signal transduction, the plant-pathogen interaction, and the flavone and flavonol biosynthesis pathways were significantly up-regulated with the increasing age of cutting seedlings propagated from 300- and 700-year-old donors. A total of 104,764 differentially expressed genes were calculated using weighted gene co-expression network analysis, and 8 gene modules were obtained. Further, 10 hub genes in the blue module were identified, which revealed that the expression levels of JAZ, FLS, RPM1/RPS3, CML, and RPS2 increased with the increase in tree age. The results demonstrated that the age of the donors seriously affected the growth of P. orientalis cutting seedlings and that cutting propagation can preserve the resistance of ancient trees. The results of this study provide important insights into the effects of age on asexually propagated seedlings, reveal potential molecular mechanisms, and contribute to an improvement in the level of breeding and conservation of ancient germplasm resources of P. orientalis trees.

Effect of Sucrose on the Formation of Advanced Glycation End-Products of Ground Pork during Freeze-Thaw Cycles and Subsequent Heat Treatment.

The changes in protein degradation (TCA-soluble peptides), Schiff bases, dicarbonyl compounds (glyoxal-GO, methylglyoxal-MGO) and two typical advanced glycation end-products (AGEs) including Nε-carboxymethyllysine (CML), Nε-carboxyethyllysine (CEL) levels in ground pork supplemented with sucrose (4.0%) were investigated under nine freeze-thaw cycles and subsequent heating (100 °C/30 min). It was found that increase in freeze-thaw cycles promoted protein degradation and oxidation. The addition of sucrose further promoted the production of TCA-soluble peptides, Schiff bases and CEL, but not significantly, ultimately leading to higher levels of TCA-soluble peptides, Schiff bases, GO, MGO, CML, and CEL in the ground pork with the addition of sucrose than in the blank groups by 4%, 9%, 214%, 180%, 3%, and 56%, respectively. Subsequent heating resulted in severe increase of Schiff bases but not TCA-soluble peptides. Contents of GO and MGO all decreased after heating, while contents of CML and CEL increased.

Advanced Glycation End Products and Bone Metabolism in Patients with Chronic Kidney Disease.

Advanced glycation end products (AGEs) accumulation may be involved in the progression of CKD-bone disorders. We sought to determine the relationship between AGEs measured in the blood, skin, and bone with histomorphometry parameters, bone protein, gene expression, and serum biomarkers ofbone metabolism in patients with CKD stages 3 to 5D patients. Serum levels of AGEs were estimated by pentosidine, glycated hemoglobin (A1c), and N-carboxymethyl lysine (CML). The accumulation of AGEs in the skin was estimated from skin autofluorescence (SAF). Bone AGEs accumulation and multiligand receptor for AGEs (RAGEs) expression were evaluated by immunohistochemistry; bone samples were used to evaluate protein and gene expression and histomorphometric analysis. Data are from 86 patients (age: 51 ± 13 years; 60 [70%] on dialysis). Median serum levels of pentosidine, CML, A1c, and SAF were 71.6pmol/mL, 15.2ng/mL, 5.4%, and 3.05 arbitrary units, respectively. AGEs covered 3.92% of trabecular bone and 5.42% of the cortical bone surface, whereas RAGEs were expressed in 0.7% and 0.83% of trabecular and cortical bone surfaces, respectively. AGEs accumulation in bone was inversely related to serum receptor activator of NF-κB ligand/parathyroid hormone (PTH) ratio (R=-0.25; p=0.03), and RAGE expression was negatively related to serum tartrate-resistant acid phosphatase-5b/PTH (R=-0.31; p=0.01). Patients with higher AGEs accumulation presented decreased bone protein expression (sclerostin [1.96 (0.11-40.3) vs. 89.3 (2.88-401) ng/mg; p=0.004]; Dickkopf-related protein 1 [0.064 (0.03-0.46) vs. 1.36 (0.39-5.87) ng/mg; p=0.0001]; FGF-23 [1.07 (0.4-32.6) vs. 44.1 (6-162) ng/mg; p=0.01]; and osteoprotegerin [0.16 (0.08-2.4) vs. 6.5 (1.1-23.7) ng/mg; p=0.001]), upregulation of the p53 gene, and downregulation of Dickkopf-1 gene expression. Patients with high serum A1c levels presented greater cortical porosity and Mlt and reduced osteoblast surface/bone surface, eroded surface/bone surface, osteoclast surface/bone surface, mineral apposition rate, and adjusted area. Cortical thickness was negatively correlated with serum A1c (R=-0.28; p=0.02) and pentosidine levels (R=-0.27; p=0.02). AGEs accumulation in the bone of CKD patients was related to decreased bone protein expression, gene expression changes, and increased skeletal resistance to PTH; A1c and pentosidine levels were related to decreased cortical thickness; and A1c levels were related to increased cortical porosity and Mlt. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Comparison of tissue distribution of free and protein bound Nɛ-carboxymethyllysine after long-term oral administration to mice

Nɛ-Carboxymethyl-lysine (CML) is a primary advanced glycation end product that exists in the body and food as free and bound forms with different bioavailability and physiological effects. To compare the uptake, tissue distribution, and fecal excretion of dietary free and bound CML, free or bound CML were administered to healthy mice at 10 mg CML kg−1 body weight per day for 12 weeks. The results demonstrated that free CML was significantly absorbed in serum and accumulated in the colon, ileum, lung, kidneys, heart, spleen, brain, and liver after intake of free and bound CML, whereas no statistical increase was found in the accumulation of bound CML in the serum, lung, spleen, kidneys, and liver. The colon was the main tissue for the accumulation of free and total CML. Moreover, the accumulation of free CML in tissues and organs was significantly correlated with free CML levels in serum. In conclusion, consumption of bound CML caused a higher uptake, accumulation, and fecal excretion of CML in the body than intake of free CML.

Effects of frozen temperature and multiple freeze–thaw cycles on gel structure, protein and lipid oxidation and formation of advanced glycation end‐products in unwashed silver carp surimi

SummaryThe effects of frozen temperature (−18 or −60 °C) and multiple freeze–thaw (FT) cycles on the gel structure, protein denaturation and oxidation, lipid oxidation and formation of protein‐bound Nε‐carboxymethyllysine (CML) and Nε‐carboxyethyllysine (CEL) in unwashed silver carp surimi were investigated. The levels of CML and CEL in raw and heat‐treated surimi increased due to multiple FT treatment, which were positively correlated with the thiobarbituric acid‐reactive substances (TBARS) and protein carbonyl content that also increased during FT cycles, and negatively correlated with the total sulfhydryl content and Ca2+‐ATPase activity that decreased during FT cycles. Besides, the gel structure of unwashed surimi was improved by 3 FT cycles and frozen at −60 °C, which was significantly helpful to inhibit the formation of protein carbonyl and CEL in raw surimi, but showed no significant influence on the TBARS and CML levels as compared to that at −18 °C.

High serum levels of N-epsilon-carboxymethyllysine are associated with poor coronary collateralization in type 2 diabetic patients with chronic total occlusion of coronary artery

BackgroundThe formation of advanced glycation end-products (AGEs) is a crucial risk factor for the pathogenesis of cardiovascular diseases in diabetes. We investigated whether N-epsilon-carboxymethyllysine (CML), a major form of AGEs in vivo, was associated with poor coronary collateral vessel (CCV) formation in patients with type 2 diabetes mellitus (T2DM) and chronic total occlusion (CTO) of coronary artery.MethodsThis study consisted of 242 T2DM patients with coronary angiographically documented CTO. Blood samples were obtained and demographic/clinical characteristics were documented. The coronary collateralization of these patients was defined according to Rentrop or Werner classification. Serum CML levels were evaluated using ELISA assay. Receiver operating characteristic curve and multivariable regression analysis were performed.Results242 patients were categorized into poor CCV group or good CCV group (107 vs. 135 by the Rentrop classification or 193 vs. 49 by the Werner classification, respectively). Serum CML levels were significantly higher in poor CCV group than in good CCV group (110.0 ± 83.35 vs. 62.95 ± 58.83 ng/ml by the Rentrop classification and 94.75 ± 78.29 ng/ml vs. 40.37 ± 28.69 ng/ml by Werner classification, both P < 0.001). Moreover, these CML levels were also significantly different across the Rentrop and Werner classification subgroups (P < 0.001). In multivariable logistic regression, CML levels (P < 0.001) remained independent determinants of poor CCV according to the Rentrop or Werner classification after adjustment of traditional risk factors.ConclusionsThis study suggests that higher serum CML level is associated with poor collateralization in T2DM patients with CTO.

Association of Circulating IgE and CML Levels with In-Stent Restenosis in Type 2 Diabetic Patients with Stable Coronary Artery Disease.

Background: We investigated whether serum levels of immunoglobin (Ig) E and Nε-carboxymethyl-lysine (CML) are related to in-stent restenosis (ISR) in patients with stable coronary artery disease and type 2 diabetes mellitus (T2DM). Methods: Serum levels of IgE and CML were measured in 196 ISR patients and 220 non-ISR patients with stable angina and T2DM who received angiographic follow-up 12 months after percutaneous coronary intervention (PCI) with third-generation drug-eluting stent (DES) implantation for de novo lesions. Multivariate logistic regression analysis was performed to assess the association between IgE or CML and ISR. Results: Both IgE and CML levels were higher in patients with ISR compared with non-ISR patients (IgE: 187.10 (63.75–489.65) vs. 80.25 (30.65–202.50), p < 0.001; CML: 203.26 (164.50–266.84) vs. 174.26 (130.85–215.56), p < 0.001). The rate of ISR increased stepwise with increasing tertiles of IgE and CML levels (p for all trends < 0.001), and IgE correlated significantly with CML. After adjusting for potential confounders, IgE and CML levels remained independently associated with ISR. Moreover, IgE and CML levels improved the predictive capability of traditional risk factors for ISR, and there existed an interaction between IgE and CML in relation to ISR (p for interaction < 0.01). Conclusion: Elevated circulating IgE and CML levels confer an increased risk for ISR after DES-based PCI in type 2 diabetic patients with stable coronary artery disease.