Alterations of glycosaminoglycan metabolism in the development of diabetic complications in relation to metabolic control

Mechanistic evaluation of enhanced graphene toxicity to Bacillus induced by humic acid adsorption

The extensive application of graphene nanosheets (GNSs) has raised concerns over risks to sensitive species in the aquatic environment. The humic acid (HA) corona is traditionally considered to reduce GNSs toxicity. Here, we evaluate the effect of sorbed HA (GNSs-HA) on the toxicity of GNSs to Gram positive Bacillus tropicus. Contrary to previous data, GNSs-HA exhibits greater toxicity compared to GNSs. Multi-omics combined with sensitive bioassays and electrochemical methods reveals GNSs disrupt oxidative phosphorylation by causing physical membrane damage. This leads to the accumulation of intracellular reactive oxygen species and inhibition of ATP production, subsequently suppressing synthetic and metabolic processes and ultimately causing bacterial death. Conversely, GNSs-HA directly extracts electrons from bacteria and oxidized biomolecules due to HA-improved electron transfer. This finding suggests that the HA corona does not always mitigate the toxicity of nanoparticles, thereby introducing uncertainty over the interaction between environmental corona and nanoparticles during ecological risk evaluation.

Urinary sulphated glycosaminoglycans excretion in obese patients with type 2 diabetes mellitus treated with metformin

OBJECTIVE

The pattern of urinary excretion of total sulphated glycosaminoglycans (GAGs) and their particular types: chondroitin sulphate/dermatan sulphate (CS/DS) and heparan sulphate (HS) was analysed in obese patients with type 2 diabetes mellitus (T2DM) treated with metformin in monotherapy for the period of six months.

METHODS

The urinary sulphated glycosaminoglycans were quantitated using standardised dye (1.9-dimethylmethylene blue)-binding method and normalised to creatinine level.

RESULTS

Urinary total GAGs, CS/DS and HS levels were significantly higher in untreated diabetic patients in comparison to healthy subjects. Moreover, it was observed that urinary total GAGs, CS/DS and HS levels in diabetic patients after six-month metformin therapy were significantly decreased versus pre-treatment situation.

CONCLUSIONS

The obtained results suggest that the six-month treatment with metformin in obese patients with T2DM has a regulating influence on the systemic changes in proteoglycans/glycosaminoglycans, resulting in a decrease in the urinary excretion of total GAGs, CS/DS and HS.

Clinical relevance of serum α-l-fucosidase activity in the SARS-CoV-2 infection

Background and aims

The reduced fucosylation in the spike glycoprotein of SARS-CoV-2 and the IgG antibody has been observed in COVID-19. However, the clinical relevance of α-l-fucosidase, the enzyme for defucosylation has not been discovered.

Materials and methods

585 COVID-19 patients were included to analyze the correlations of α-l-fucosidase activity with the nucleic acid test, IgM/IgG, comorbidities, and disease progression.

Results

Among the COVID-19 patients, 5.75% were double-negative for nucleic acid and antibodies. All of them had increased α-l-fucosidase, while only one had abnormal serum amyloid A (SAA) and C-reactive protein (CRP). The abnormal rate of α-l-fucosidase was 81.82% before the presence of IgM, 100% in the presence of IgM, and 66.2% in the presence of IgG. 73.42% of patients with glucometabolic disorders had increased α-l-fucosidase activity and had the highest mortality of 6.33%. The increased α-l-fucosidase was observed in 55.8% of non-severe cases and 72.9% of severe cases, with an odds ratio of 2.118. The α-l-fucosidase mRNA was irrelevant to its serum activity.

Conclusion

The change in α-l-fucosidase activity in COVID-19 preceded the IgM and SAA and showed a preferable relation with glucometabolic disorders, which may be conducive to virus invasion or invoke an immune response against SARS-CoV-2.

An At-Risk Population Screening Program for Mucopolysaccharidoses by Measuring Urinary Glycosaminoglycans in Taiwan

Background: The mucopolysaccharidoses (MPSs) are a group of rare lysosomal storage disorders characterized by the accumulation of glycosaminoglycans (GAGs) and which eventually cause progressive damage to various tissues and organs. We developed a feasible MPS screening algorithm and established a cross-specialty collaboration platform between medical geneticists and other medical specialists based on at-risk criteria to allow for an earlier confirmative diagnosis of MPS. Methods: Children (<19 years of age) with clinical signs and symptoms compatible with MPS were prospectively enrolled from pediatric clinics between July 2013 and June 2018. Urine samples were collected for a non-specific total GAG analysis using the dimethylmethylene blue (DMB) spectrophotometric method, and the quantitation of three urinary GAGs (dermatan sulfate (DS), heparan sulfate (HS), and keratan sulfate (KS)) was performed by liquid chromatography/tandem mass spectrometry (LC-MS/MS). The subjects with elevated urinary GAG levels were recalled for leukocyte enzyme activity assay and genetic testing for confirmation. Results: Among 153 subjects enrolled in this study, 13 had a confirmative diagnosis of MPS (age range, 0.6 to 10.9 years—three with MPS I, four with MPS II, five with MPS IIIB, and one with MPS IVA). The major signs and symptoms with regards to different systems recorded by pediatricians at the time of the decision to test for MPS were the musculoskeletal system (55%), followed by the neurological system (45%) and coarse facial features (39%). For these 13 patients, the median age at the diagnosis of MPS was 2.9 years. The false negative rate of urinary DMB ratio using the dye-based method for these 13 patients was 31%, including one MPS I, two MPS IIIB, and one MPS IVA. However, there were no false negative results with urinary DS, HS and KS using the MS/MS-based method. Conclusions: We established an at-risk population screening program for MPS by measuring urinary GAG fractionation biomarkers using the LC-MS/MS method. The program included medical geneticists and other medical specialists to increase awareness and enable an early diagnosis by detecting MPS at the initial onset of clinical symptoms.

Serum heparan sulfate and chondroitin sulfate concentrations in patients with newly diagnosed exfoliative glaucoma

Background

Exfoliative glaucoma (XFG) is typically classified as a high-pressure type of secondary open-angle glaucoma that develops as a consequence of exfoliation syndrome (XFS). Exfoliation syndrome is an age-related, generalized disorder of the extracellular matrix characterized by production and progressive accumulation of a fibrillar exfoliation material (XFM) in intra- and extraocular tissues. Exfoliation material represents complex glycoprotein/proteoglycan structure composed of a protein core surrounded by glycosaminoglycans such as heparan sulfate (HS) and chondroitin sulfate (CS). The purpose of the present study was to investigate HS and CS concentrations in serum samples of patients with newly diagnosed XFG and compare the obtained values with those pertaining to newly diagnosed primary open-angle glaucoma (POAG), normal controls (NC) and subjects with XFS.

Methods

This case–control study involved 165 subjects, including patients with newly diagnosed XFG, patients with newly diagnosed POAG, subjects with XFS and age- and sex-matched NC. The study was conducted at the Glaucoma Department of Clinic for Eye Diseases, Clinical Centre of Serbia, as the referral center for glaucoma in Serbia.

Results

The mean age in the XFG, POAG, XFS and NC groups was 73.3 ± 9.0, 66.3 ± 7.8, 75.5 ± 7.0 and 73.5 ± 9.5 years, respectively, XFG vs. POAG, p < 0.001. Mean serum HS concentrations in the XFG, POAG, NC and XFS groups were 3,189.0 ± 1,473.8 ng/mL, 2,091.5 ± 940.9 ng/mL, 2,543.1 ± 1,397.3 ng/mL and 2,658.2 ± 1,426.8 ng/mL respectively, XFG vs. POAG, p = 0.001 and XFG vs. NC, p = 0.032. Mean serum CS concentrations in the XFG, POAG, NC and XFS group were 43.9 ± 20.7 ng/mL, 38.5 ± 22.0 ng/mL, 35.8 ± 16.4 ng/mL and 43.3 ± 21.8 ng/mL, respectively, XFG vs. NC, p = 0.041.

Conclusions

Our findings revealed greater HS and CS concentrations in XFG patients and XFS subjects compared to those without XFM. Implications of HS and CS in the pathophysiology of XFS and glaucoma should be studied further. Serum is easily accessible and should thus be explored as rich sources of potential biomarkers. Further research should aim to identify XFG biomarkers that could be utilized in routine blood analysis tests, aiding in timely disease diagnosis.

Urine protein, urine protein to creatinine ratio and N-acetyl-β-D-glucosaminidase index in cats with idiopathic cystitis vs healthy control cats

Objectives The objective was to compare urine protein, urine protein to creatinine ratio (UPC) and N-acetyl-β-D-glucosaminidase (NAG) index between cats with idiopathic cystitis and clinically normal cats. Methods Urine and blood samples were collected from 19 clinically normal cats and 19 cats with idiopathic cystitis without azotaemia at the time of first presentation. Urine protein, urine creatinine and UPC were measured. Additionally, the urinary NAG concentration was measured using the colorimetric method, and the NAG index was calculated by dividing the urinary NAG concentration by the urine creatinine ratio. Results Urine protein concentration (mean ± SEM) was four times higher in cats with idiopathic cystitis (218.29 ± 58.95) than in clinically normal cats (56.13 ± 9.95) (P <0.05). The UPC (mean ± SEM) of cats with idiopathic cystitis (0.70 ± 0.19) was also five times higher than that of clinically normal cats (0.14 ± 0.02) (P <0.05). The mean ± SEM NAG index in cats with idiopathic cystitis (4.79 ± 1.53 U/g) was two times higher than that in clinically normal cats (2.14 ± 0.48 U/g). The log UPC was positively correlated with the log NAG index in cats with idiopathic cystitis at moderate levels (r2 = 0.512; P <0.05). Conclusions and relevance Cats with idiopathic cystitis had increased amounts of urine protein and an increased UPC. Further study is needed to address the role of urinary NAG and its relationship with glycosaminoglycan levels in cats with idiopathic cystitis.

A selective screening program for the early detection of mucopolysaccharidosis: Results of the FIND project - a 2-year follow-up study

The mucopolysaccharidoses (MPSs) are underdiagnosed but they are evaluated in few newborn screening programs, probably due to the many challenges remaining, such as the identification of late-onset phenotypes. Systematic screening at the onset of clinical symptoms could help to early identify patients who may benefit from specific treatments. The aim of this prospective study was to assess a novel selective screening program, the FIND project, targeting patients aged 0 to 16 years with clinical manifestations of MPS. The project was designed to increase awareness of these diseases among pediatricians and allow early diagnosis.From July 2014 to June 2016, glycosaminoglycan (GAG) levels normalized to creatinine levels were determined in urine-impregnated analytical paper submitted by pediatricians who had patients with clinical signs and/or symptoms compatible with MPS. When high GAG concentrations were detected, a new liquid urine sample was requested to confirm and identify the GAG present. When a specific form of MPS was suspected, enzyme activity was analyzed using blood-impregnated paper to determine MPS type (I, IIIB, IIIC, IVA, IVB, VI, or VII). Age-specific reference values for GAG were previously established using 145 urine samples from healthy children.GAG levels were normal in 147 (81.7%) of the 180 initial samples received. A liquid sample was requested for the other 33 cases (18.3%); GAG levels were normal in 13 of these and slightly elevated in 12, although the electrophoresis study showed no evidence of MPS. Elevated levels with corresponding low enzymatic activity were confirmed in 8 cases. The mean time from onset of clinical symptoms to detection of MPS was 22 months, and just 2 cases were detected at the beginning of the project were detected with 35 and 71 months of evolution of clinical symptoms. Our screening strategy for MPS had a sensitivity of 100%, a specificity of 85%, and a positive predictive value of 24%.The FIND project is a useful and cost-effective screening method for increasing awareness of MPS among pediatricians and enabling the detection of MPS at onset of clinical symptoms.

Newborn screening for mucopolysaccharidoses: a pilot study of measurement of glycosaminoglycans by tandem mass spectrometry

BACKGROUND

Mucopolysaccharidoses (MPS) are a group of inborn errors of metabolism that are progressive and usually result in irreversible skeletal, visceral, and/or brain damage, highlighting a need for early diagnosis.

METHODS

This pilot study analyzed 2862 dried blood spots (DBS) from newborns and 14 DBS from newborn patients with MPS (MPS I, n = 7; MPS II, n = 2; MPS III, n = 5). Disaccharides were produced from polymer GAGs by digestion with chondroitinase B, heparitinase, and keratanase II. Heparan sulfate (0S, NS), dermatan sulfate (DS) and mono- and di-sulfated KS were measured by liquid chromatography tandem mass spectrometry (LC-MS/MS). Median absolute deviation (MAD) was used to determine cutoffs to distinguish patients from controls. Cutoffs were defined as median + 7× MAD from general newborns.

RESULTS

The cutoffs were as follows: HS-0S > 90 ng/mL; HS-NS > 23 ng/mL, DS > 88 ng/mL; mono-sulfated KS > 445 ng/mL; di-sulfated KS > 89 ng/mL and ratio di-KS in total KS > 32 %. All MPS I and II samples were above the cutoffs for HS-0S, HS-NS, and DS, and all MPS III samples were above cutoffs for HS-0S and HS-NS. The rate of false positives for MPS I and II was 0.03 % based on a combination of HS-0S, HS-NS, and DS, and for MPS III was 0.9 % based upon a combination of HS-0S and HS-NS.

CONCLUSIONS

Combination of levels of two or more different GAGs improves separation of MPS patients from unaffected controls, indicating that GAG measurements are potentially valuable biomarkers for newborn screening for MPS.

Predictive Potential of Twenty-Two Biochemical Biomarkers for Coronary Artery Disease in Type 2 Diabetes Mellitus

We investigated the potential of a panel of 22 biomarkers to predict the presence of coronary artery disease (CAD) in type 2 diabetes mellitus (DM2) patients. The study enrolled 96 DM2 patients with (n = 75) and without (n = 21) evidence of CAD. We assessed a biochemical profile that included 22 biomarkers: total cholesterol, LDL, HDL, LDL/HDL, triglycerides, glucose, glycated hemoglobin, fructosamine, homocysteine, cysteine, methionine, reduced glutathione, oxidized glutathione, reduced glutathione/oxidized glutathione, L-arginine, asymmetric dimethyl-L-arginine, symmetric dimethyl-L-arginine, asymmetric dimethyl-L-arginine/L-arginine, nitrate plus nitrite, S-nitrosothiols, nitrotyrosine, and n-acetyl-β-glucosaminidase. Prediction models were built using logistic regression models. We found that eight biomarkers (methionine, nitratate plus nitrite, n-acetyl-β-glucosaminidase, BMI, LDL, HDL, reduced glutathione, and L-arginine/asymmetric dimethyl-L-arginine) along with gender and BMI were significantly associated with the odds of CAD in DM2. These preliminary findings support the notion that emerging biochemical markers might be used for CAD prediction in patients with DM2. Our findings warrant further investigation with large, well-designed studies.

Glycosaminoglycans in the blood of hereditary multiple exostoses patients: Half reduction of heparan sulfate to chondroitin sulfate ratio and the possible diagnostic application

Hereditary multiple exostoses (HME) is an autosomal dominant skeletal disorder with wide variation in clinical phenotype and is caused by heterogeneous germline mutations in two of the Ext genes, EXT-1 and EXT-2, which encode ubiquitously expressed glycosyltransferases involved in the polymerization of heparan sulfate (HS) chains. To examine whether the Ext mutation could affect HS structures and amounts in HME patients being heterozygous for the Ext genes, we collected blood from patients and healthy individuals, separated it into plasma and cellular fractions and then isolated glycosaminoglycans (GAGs) from those fractions. A newly established method consisting of a combination of selective ethanol precipitation of GAGs, digestion of GAGs recovered on the filter-cup by direct addition of heparitinase or chondroitinase reaction solution and subsequent high-performance liquid chromatography of the unsaturated disaccharide products enabled the analysis using the least amount of blood (200 µL). We found that HS structures of HME patients were almost similar to those of controls in both plasma and cellular fractions. However, interestingly, although both the amounts of HS and chondroitin sulfate (CS) varied depending on the different individuals, the amounts of HS in both the plasma and cellular fractions of HME patient samples were decreased and the ratios of HS to CS (HS/CS) of HME patient samples were almost half those of healthy individuals. The results suggest that HME patients' blood exhibited reduced HS amounts and HS/CS ratios, which could be used as a diagnostic biomarker for HME.

A comprehensive compositional analysis of heparin/heparan sulfate-derived disaccharides from human serum

The analysis of heparan sulfate glycosaminoglycans (HSGAGs) variations in human serum at the disaccharide level has a great potential for disease diagnosis and prognosis. However, the lack of available analytical methodology for the compositional analysis of HSGAGs in human serum remains to be addressed to delineate the possible role of HSGAGs on the onset and/or progression of a disease. In this study, we have developed a method for the in-depth compositional analysis of the 12 heparin/HS-derived disaccharides from human serum using a combination of technologies--fractionation, exhaustive digestion, solid phase extraction, and LC-MS/MS. The method exhibits high recovery (72-110%) and good reproducibility (standard deviation of less than 5%) with a low limit of detection and quantification. Errors from the method validation were within 1.1%. Nondetectable non- or low-sulfated disaccharides in human serum were also detected using the optimized protocol. Further applying this method, the comprehensive analysis of HSGAGs compositions in human sera from female donors showed considerable variations in disaccharide patterns and compositions.

Quantitative determination and comparison of the glycosaminoglycan Delta-disaccharide composition in 22 different human cell lines

Changes in proteoglycan and glycosaminoglycan (GAG) content and distribution may play an important role in the development of many diseases, atherosclerosis, cancer and diabetes. Human cell lines act as models for the underlying pathomechanisms. Despite the importance of proteoglycans for cell functioning, information on the GAG composition of most human cell lines is limited. Comparative analysis of the GAG Deltadisaccharide amount in 22 human cell lines yielded a mean value of 94 +/- 58 pmol/10(6) cells (mean+/-SEM). Total GAG amount and heparan sulfate/heparin Deltadisaccharide composition, but not chondroitin sulfate/dermatan sulfate Deltadisaccharide composition, differed significantly between the investigated adherent and suspension cell lines. We provide a novel overview of GAG Deltadisaccharide composition in 22 different human cell lines.

The xylosyltransferase Iota gene polymorphism c.343G>T (p.A115S) is associated with decreased serum glycosaminoglycan levels

OBJECTIVES

The xylosyltransferases I and II (XT-I, XT-II, EC 2.4.2.26) are the chain-initiating enzymes in the biosynthesis of glycosaminoglycans (GAGs). This is the first investigation of changes in the serum GAG amount and composition in association with polymorphisms in XYLT1 and XYLT2.

DESIGN AND METHODS

Genotyping of three genetic variations in the genes XYLT1 and XYLT2 was performed in 223 healthy blood donor samples. Serum samples were analyzed for their GAG Delta-disaccharide content by reversed-phase high-performance liquid chromatography (RP-HPLC). Furthermore serum XT activity was determined by a radiochemical assay.

RESULTS

The single nucleotide polymorphism (SNP) c.343G>T in XYLT1 exon 1 correlated with a significantly decreased GAG content in the serum (p<0.01). For the other two investigated XYLT2 variations (c.166G>A in exon 2 and c.1253C>T in exon 6) no changes in the serum GAG amount were detected. No investigated SNPs were associated with changes to serum XT activities.

CONCLUSIONS

The XYLT1 SNP c.343G>T is associated with a decreased GAG amount in the serum of healthy blood donors.

Biomarkers of oxidative stress and endothelial dysfunction in glucose intolerance and diabetes mellitus

OBJECTIVES

To evaluate biomarkers of endothelial dysfunction and oxidative stress in glucose intolerance (GI) compared to overt diabetes (DM2).

DESIGN AND METHODS

140 volunteers including 96 with DM2, 32 with GI and 12 controls (C) were studied. (*)NO metabolites, (*)NO synthase inhibitors, thiols and N-acetyl-beta-glucosaminidase (NAGase) activity were analyzed by chemiluminescence, capillary electrophoresis, ELISA and colorimetric assay, respectively.

RESULTS

(*)NO metabolites were higher in GI (NOx: p=0.03; S-nitrosothiols: p=0.001) and DM2 (p=0.006; p=0.0006) groups in relation to group C, while nitrotyrosine was higher only in the DM2 group in comparison to the other groups. NAGase activity was elevated in GI (p=0.003) and DM2 (p=0.0004) groups in relation to group C, as well as, ADMA (p=0.01; p=0.003) and GSSG (p=0.01; p=0.002).

CONCLUSIONS

(*)NO metabolites, (*)NO synthase inhibitors, thiols and NAGase are biomarkers suitable to indicate endothelial dysfunction and oxidative stress in the early stages of impaired response to insulin.

Serum N-acetyl-beta-D-glucosaminidase profiles in type 1 diabetes secondary complications: causes of changes and significance of determination

The connection between changes in the activity of serum N-acetyl-beta-D-glucosaminidase (NAG, E.C.3.2.1.30) and iso-enzymes and degree of secondary complications was analyzed in four groups of type 1 diabetic patients (n=69): without complications (n=22); with retinopathy (n=16); with retinopathy and polyneuropathy (n=13), and with retinopathy, neuropathy, and nephropathy (n=18). In all groups statistically significant higher (P<0.001) percent fraction of A form (83.84+/-6.09, 84.37+/-5.74, 81.76+/-6.02, 76.37+/-7.38%, resp.) and lower (P<0.001, P<0.01) fraction of B form (15.87+/-5.65, 15.66+/-5.74, 18.33+/-5.98, 23.63+/-7.38, resp.) in total NAG compared with the control (A=69.38+/-4.79%, B=30.61+/-4.78%) were found. The differences in A as well as B forms between diabetic groups were not statistically significant. Significant strong positive correlations between total NAG and glycemia (0.494-0.623), total NAG and A form (0.934-0.966), and A form and glycemia (0.512-0.638) were found in all groups. No correlation was found between the fractions of B and A forms, except in the fourth group. The A form of diabetic patients in the fourth group was more acidic compared with the control and other diabetic groups. It was concluded that the changes in serum NAG and iso-enzymic profiles in diabetes are the consequence of its increased exocytose, especially of the A form, in hyperglycemia and posttranslational modifications of iso-enzymes. The total activity of serum NAG and iso-enzymic profiles cannot be used for monitoring the development and distinction of type 1 diabetes secondary complications.

Quantitative determination of the glycosaminoglycan Delta-disaccharide composition of serum, platelets and granulocytes by reversed-phase high-performance liquid chromatography

Seven Delta-disaccharide standards from heparan sulfate/heparin (HS/H) and nine Delta-disaccharide standards from chondroitin/dermatan sulfate (CS/DS) and hyaluronic acid (HA) were derivatized with the fluorophore 2-aminoacridone (AMAC) and separated in two runs each by reversed-phase HPLC with baseline separation and very short run times. This novel method facilitates the separation of the largest number of Delta-disaccharides from both CS/DS/HA and HS/H with one column and buffer system after fluorophore labeling in two runs at present. For the first time nine glycosaminoglycan (GAG) Delta-disaccharides from CS/DS/HA were separated after fluorophore labeling in one run. The limits of quantification (LOQs) were below 0.2 pmol for CS/DS/HA and HS/H Delta-disaccharides. We demonstrated applicability of our method for biological samples. Furthermore, normal ranges of the GAG Delta-disaccharide compositions from platelets and granulocytes were determined for the first time.