Glycome Patterns of Perfusate in Livers Before Transplantation Associate With Primary Nonfunction.

BACKGROUND & AIMS: Primary nonfunction (PNF) is a rare complication after liver transplantation that requires urgent retransplantation. PNF is associated with livers from extended criteria donors. Clinical and biochemical factors have not been identified that reliably associate with graft function after liver transplantation. Serum patterns of N-glycans associate with changes in the liver. We analyzed perfusate from grafted liver to identify protein glycosylation patterns associated with PNF. METHODS: We performed a prospective study of consecutive patients who underwent liver transplantation (66 patients, from 1 center, in the derivation set, and 56 patients, from 2 centers, in the validation set) in Belgium, from October 1, 2011, through April 30, 2017. All donor grafts were transported using cold static storage, and perfusate samples were collected from the livers by flushing of hepatic veins before transplantation. Protein-linked N-glycans were isolated from perfusate samples and analyzed with a multicapillary electrophoresis-based ABI3130 sequencer. We compared glycan patterns between patients with vs without PNF of transplanted livers. PNF was defined as the need for urgent retransplantation when a graft had no evidence of function, after exclusion of other causes, such as hepatic artery thrombosis or acute cellular rejection. RESULTS: The relative abundance of a single glycan, agalacto core-alpha-1,6-fucosylated biantennary glycan (NGA2F) was significantly increased in perfusate of livers given to 4 patients who developed PNF after liver transplantation compared with livers given to patients who did not develop PNF. Level of NGA2F identified patients with PNF with 100% accuracy. This glycomarker was the only factor associated with PNF in multivariate analysis in the derivation and the validation sets (P < .0001). CONCLUSIONS: In an analysis of patients who underwent liver transplantation, we associated graft perfusate level of glycan NGA2F present on perfusate proteins with development of PNF with 100% accuracy, and validated this finding in a separate cohort of patients. This biomarker might be used to assess grafts before transplantation, especially when high-risk organs are under consideration.

A Glycomics-Based Test Predicts the Development of Hepatocellular Carcinoma in Cirrhosis.

Purpose: Cirrhosis is a major risk factor for the development of hepatocellular carcinoma but remains underdiagnosed in the compensated stage. Fibrosis progression and cirrhosis are associated with changes in blood serum glycomic profiles. Previously, the serum glycomics-based GlycoCirrhoTest was shown to identify 50% to 70% of compensated cirrhosis cases in chronic liver disease cohorts, at >90% specificity. This study assessed GlycoCirrhoTest for the risk of hepatocellular carcinoma development in compensated cirrhosis.Experimental Design: Serum glycomics were analyzed in sera of 133 patients, with compensated cirrhosis collected between 1995 and 2005 in a surveillance protocol for hepatocellular carcinoma using an optimized glycomic technology on a DNA sequencer.Results: Baseline GlycoCirrhoTest values were significantly increased in patients who developed hepatocellular carcinoma after a median follow-up of 6.4 years as compared with patients who did not. For patients with a baseline GlycoCirrhoTest exceeding 0.2, the HR for hepatocellular carcinoma development over the entire study (Cox regression) was 5.1 [95% confidence interval (CI), 2.2-11.7; P < 0.001], and the HR for hepatocellular carcinoma development within 7 years was 12.1 (95% CI, 2.8-51.6; P = 0.01) based on the cut-off value optimized in the same cohort. An absolute increase in GlycoCirrhoTest of 0.2 was associated with an HR of 10.29 (95% CI, 3.37-31.43; P < 0.001) for developing hepatocellular carcinoma. In comparison, the HR for the development of hepatocellular carcinoma within 7 years for AFP levels above the optimal cutoff in this study (5.75 ng/mL) was 4.65 (95% CI, 1.59-13.61).Conclusions: This prognostic study suggests that GlycoCirrhoTest is a serum biomarker that identifies compensated cirrhotic patients at risk for developing hepatocellular carcinoma. Screening strategies could be guided by a positive test on GlycoCirrhoTest. Clin Cancer Res; 23(11); 2750-8. ©2016 AACR.

Urinary prostate protein glycosylation profiling as a diagnostic biomarker for prostate cancer.

BACKGROUND: Serum prostate-specific antigen (sPSA) measurement is widely used as opportunistic screening tool for prostate cancer (PCa). sPSA suffers from considerable sensitivity and specificity problems, particularly in the diagnostic gray zone (sPSA 4-10 µg/L). Furthermore, sPSA is not able to discriminate between poorly-, moderately-, and well-differentiated PCa. We investigated prostatic protein glycosylation profiles as a potential PCa biomarker. METHODS: Differences in total urine N-glycosylation profile of prostatic proteins were determined between healthy volunteers (n = 54), patients with benign prostate hyperplasia (BPH; n = 93) and newly diagnosed PCa patients (n = 74). Variations in N-glycosylation profile and prostate volume were combined into one urinary glycoprofile marker (UGM). Additionally, differences in N-glycosylation were identified between Gleason <7, =7, and >7. RESULTS: The UGM was able to discriminate BPH from PCa, overall and in the diagnostic gray zone (P < 0.001). The UGM showed comparable diagnostic accuracy to sPSA, but gave an additive diagnostic value to sPSA (P < 0.001). In the diagnostic gray zone the UGM performed significantly better than sPSA (P < 0.001). A significant difference was found in core-fucosylation of biantennary structures and overall core-fucosylation of multiantennary structures between Gleason < 7 and Gleason > 7 (P = 0.010 and P = 0.020, respectively) and between Gleason = 7 and Gleason > 7 (P = 0.011 and P = 0.025, respectively). CONCLUSIONS: The UGM shows high potential as PCa biomarker, particularly in the diagnostic gray zone. Further research is needed to validate these findings.

Multiple phenotypes in phosphoglucomutase 1 deficiency.

BACKGROUND: Congenital disorders of glycosylation are genetic syndromes that result in impaired glycoprotein production. We evaluated patients who had a novel recessive disorder of glycosylation, with a range of clinical manifestations that included hepatopathy, bifid uvula, malignant hyperthermia, hypogonadotropic hypogonadism, growth retardation, hypoglycemia, myopathy, dilated cardiomyopathy, and cardiac arrest. METHODS: Homozygosity mapping followed by whole-exome sequencing was used to identify a mutation in the gene for phosphoglucomutase 1 (PGM1) in two siblings. Sequencing identified additional mutations in 15 other families. Phosphoglucomutase 1 enzyme activity was assayed on cell extracts. Analyses of glycosylation efficiency and quantitative studies of sugar metabolites were performed. Galactose supplementation in fibroblast cultures and dietary supplementation in the patients were studied to determine the effect on glycosylation. RESULTS: Phosphoglucomutase 1 enzyme activity was markedly diminished in all patients. Mass spectrometry of transferrin showed a loss of complete N-glycans and the presence of truncated glycans lacking galactose. Fibroblasts supplemented with galactose showed restoration of protein glycosylation and no evidence of glycogen accumulation. Dietary supplementation with galactose in six patients resulted in changes suggestive of clinical improvement. A new screening test showed good discrimination between patients and controls. CONCLUSIONS: Phosphoglucomutase 1 deficiency, previously identified as a glycogenosis, is also a congenital disorder of glycosylation. Supplementation with galactose leads to biochemical improvement in indexes of glycosylation in cells and patients, and supplementation with complex carbohydrates stabilizes blood glucose. A new screening test has been developed but has not yet been validated. (Funded by the Netherlands Organization for Scientific Research and others.).

Capillary electrophoresis of urinary prostate glycoproteins assists in the diagnosis of prostate cancer.

Prostate marker assays are widely used for detection of prostate cancer (PCa) but are associated with considerable sensitivity and specificity problems. Therefore, we investigated prostatic protein glycosylation profiles as a potential biomarker. We determined the urinary asparagine-linked glycan (N-glycan) profile of prostatic proteins of healthy volunteers (n = 25), patients with benign prostate hyperplasia (BPH; n = 62) and newly diagnosed PCa patients (n = 42) using DNA-sequencer-assisted fluorophore-assisted carbohydrate electrophoresis. Through squeezing of the prostate, a sufficient amount of prostatic proteins was obtained for direct structural analyses of N-glycan structures. N-glycans of PCa compared to BPH were characterized by a significant decrease in triantennary structures (p = 0.047) and overall fucosylation (p = 0.026). Prostate-specific antigen (PSA) and the urinary glycoprofile marker showed comparable overall receiver operating characteristic curve analysis as well as in the diagnostic gray zone with serum PSA values between 4 and 10 µg/L. However, when combining PSA and the urinary glycoprofile marker, the latter gave an additive diagnostic value to serum PSA (p ≤ 0.001). In conclusion, N-glycosylation profiling demonstrated differences between BPH and PCa. These changes could lead to the discovery of a new biomarker for PCa.

N-glycan based biomarker distinguishing non-alcoholic steatohepatitis from steatosis independently of fibrosis.

BACKGROUND: Non-alcoholic fatty liver disease is a spectrum of disorders ranging from steatosis to non-alcoholic steatohepatitis (NASH). Steatosis of the liver is benign, whereas NASH can progress to cirrhosis or even hepatocellular carcinoma. Currently, a liver biopsy is the only validated method to distinct NASH from steatosis. AIM: The objective of this study was to identify a biomarker specific for NASH based on the N-glycosylation of serum proteins. METHODS: N-glycosylation patterns were assessed using DNA sequencer-assisted fluorophore-assisted capillary electrophoresis and compared with histology. RESULTS: Initially, a glycomarker (log[NGA2F]/[NA2]) was developed based on the results obtained in 51 obese non-alcoholic patients scheduled for bariatric surgery. Multivariate analysis showed that our glycomarker had the lowest P-value of all biomarkers in distinguishing NASH from steatosis (P=0.069). The glycomarker was validated in a cohort of 224 non-alcoholic fatty liver disease patients. In both pilot and validation study, glycomarker score increased in ascending amount of lobular inflammation (single-factor ANOVA, P ≤ 0.001 and P=0.012, respectively). The N-glycan profile of immunoglobulin G in the NASH population confirmed the significantly increased undergalactosylation present in these patients. CONCLUSION: Our glycomarker specifically recognises liver inflammation in obese individuals which is the main trigger for the development of steatohepatitis and can differentiate between steatosis and NASH.

Expression analysis of the nucleocytoplasmic lectin 'Orysata' from rice in Pichia pastoris.

The Oryza sativa lectin, abbreviated Orysata, is a mannose-specific, jacalin-related lectin expressed in rice plants after exposure to certain stress conditions. Expression of a fusion construct containing the rice lectin sequence linked to enhanced green fluorescent protein in Bright Yellow 2 tobacco cells revealed that Orysata is located in the nucleus and the cytoplasm of the plant cell, indicating that it belongs to the class of nucleocytoplasmic jacalin-related lectins. Since the expression level of Orysata in rice tissues is very low the lectin was expressed in the methylotrophic yeast Pichia pastoris with the Saccharomyces α-factor sequence to direct the recombinant protein into the secretory pathway and express the protein into the medium. Approximately 12 mg of recombinant lectin was purified per liter medium. SDS/PAGE and western blot analysis showed that the recombinant lectin exists in two molecular forms. Far western blot analysis revealed that the 23 kDa lectin polypeptide contains an N-glycan which is absent in the 18.5 kDa polypeptide. Characterization of the glycans present in the recombinant Orysata revealed high-mannose structures, Man9-11 glycans being the most abundant. Glycan array analysis showed that Orysata interacts with high-mannose as well as with more complex N-glycan structures. Orysata has potent anti-human immunodeficiency virus and anti-respiratory syncytial virus activity in cell culture compared with other jacalin-related lectins.

Diagnostic value of the hemopexin N-glycan profile in hepatocellular carcinoma patients.

BACKGROUND: Hepatocellular carcinoma (HCC) is a common and rapidly fatal cancer. Current diagnostic methods for HCC have poor sensitivity and specificity, are invasive, and carry risk for complications. Newer markers are needed to overcome these problems and allow diagnosis of HCC at an earlier stage. In view of known associations between glycosylation changes and liver disease, we focused on the serum glycoprotein hemopexin and the specific characteristics of this liver-synthesized glycoprotein. METHODS: We studied 49 healthy volunteers and 81 patients divided into the categories of fibrosis, cirrhosis, and HCC with cirrhosis. Hemopexin was purified from study participants' serum by use of heme agarose beads. The hemopexin N-glycan profile was determined by use of the DNA sequencer-assisted fluorophore-assisted carbohydrate electrophoresis technique. RESULTS: We found that branching alpha-1,3-fucosylated multiantennary glycans on hemopexin were increased in the HCC group compared with the cirrhosis without HCC, fibrosis, and healthy volunteer groups, whereas nonmodified biantennary glycans decreased progressively across groups from fibrosis to the cirrhosis and HCC groups. Summarization of this information in a new marker, called the hemopexin glycan marker, enabled distinction of patients with HCC and cirrhosis from healthy volunteers and patients with fibrosis or cirrhosis with a sensitivity and specificity of 79% and 93%, respectively. CONCLUSIONS: This study demonstrated hemopexin to be a model protein for studying liver-specific N-glycosylation. The hemopexin glycan marker could be a valuable complementary test to alpha-fetoprotein measurements for detection of HCC in patients with cirrhosis. Additional study of its utility for diagnosis and follow-up is recommended.

Glycome profiling using modern glycomics technology: technical aspects and applications.

Glycomics research has become indispensable in many research fields such as immunity, signal transduction and development. Moreover, changes in the glycosylation of proteins and lipids have been reported in several diseases including cancer. The analysis of a complex post-translational modification such as glycosylation depends on the availability or development of appropriate analytical technologies. The research goal determines the sensitivity, resolution and throughput requirements and guides the choice of a particular technology. This review highlights the evolution of glycan profiling tools in the past 5 years. We focus on capillary electrophoresis, liquid chromatography, mass spectrometry and lectin microarrays.

GlycoFibroTest is a highly performant liver fibrosis biomarker derived from DNA sequencer-based serum protein glycomics.

Liver fibrosis is currently assessed by liver biopsy, a costly and rather cumbersome procedure that is unsuitable for frequent patient monitoring, which drives research into biomarkers for this purpose. To investigate whether the serum N-glycome contains information suitable for this goal, we developed a 96-well plate-based serum N-glycomics sample preparation protocol that only involves fluid transfer steps and incubations in a PCR thermocycler yielding 8-aminopyrene-1,3,6-trisulfonic acid-labeled N-glycans. These N-glycans are then ready for analysis on the capillary electrophoresis-based DNA sequencers that are the current standard in clinical genetics laboratories worldwide. Subsequently we performed a multicenter, blinded study of 376 consecutive chronic hepatitis C virus patients for which liver biopsies and extensive serum biochemistry data were available. Among patients, the METAVIR fibrosis stage distribution was as follows: 10.6% F0, 44.4% F1, 20.5% F2, 18.4% F3, and 6.1% F4. We found that the ratio of two N-glycans, here called GlycoFibroTest, correlates with the histological fibrosis stage equally well as FibroTest (rho = 0.4-0.5 in F1-F4), which is used in the clinic today. Finally using affinity chromatography we depleted sera of immunoglobulin G, and this resulted in a complete removal of the undergalactosylated biantennary glycans from the N-glycome, which are partially determining GlycoFibroTest.