Serum Aberrant N-Glycan Profile as a Marker Associated with Early Antibody-Mediated Rejection in Patients Receiving a Living Donor Kidney Transplant

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2017-2018

This review is the tenth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2018. Also included are papers that describe methods appropriate to glycan and glycoprotein analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, new methods, matrices, derivatization, MALDI imaging, fragmentation and the use of arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Most of the applications are presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. The reported work shows increasing use of combined new techniques such as ion mobility and highlights the impact that MALDI imaging is having across a range of diciplines. MALDI is still an ideal technique for carbohydrate analysis and advancements in the technique and the range of applications continue steady progress.

Mass spectrometry-based N-glycosylation analysis in kidney disease

Kidney disease is a global health concern with an enormous expense. It is estimated that more than 10% of the population worldwide is affected by kidney disease and millions of patients would progress to death prematurely and unnecessarily. Although creatinine detection and renal biopsy are well-established tools for kidney disease diagnosis, they are limited by several inevitable defects. Therefore, diagnostic tools need to be upgraded, especially for the early stage of the disease and possible progression. As one of the most common post-translational modifications of proteins, N-glycosylation plays a vital role in renal structure and function. Deepening research on N-glycosylation in kidney disease provides new insights into the pathophysiology and paves the way for clinical application. In this study, we reviewed recent N-glycosylation studies on several kidney diseases. We also summarized the development of mass spectrometric methods in the field of N-glycoproteomics and N-glycomics.

Set Up for Failure: Pre-Existing Autoantibodies in Lung Transplant

Lung transplant patients have the lowest long-term survival rates compared to other solid organ transplants. The complications after lung transplantation such as primary graft dysfunction (PGD) and ultimately chronic lung allograft dysfunction (CLAD) are the main reasons for this limited survival. In recent years, lung-specific autoantibodies that recognize non-HLA antigens have been hypothesized to contribute to graft injury and have been correlated with PGD, CLAD, and survival. Mounting evidence suggests that autoantibodies can develop during pulmonary disease progression before lung transplant, termed pre-existing autoantibodies, and may participate in allograft injury after transplantation. In this review, we summarize what is known about pulmonary disease autoantibodies, the relationship between pre-existing autoantibodies and lung transplantation, and potential mechanisms through which pre-existing autoantibodies contribute to graft injury and rejection.

Glycan Imaging Mass Spectrometry: Progress in Developing Clinical Diagnostic Assays for Tissues, Biofluids, and Cells

N-glycan imaging mass spectrometry (IMS) can rapidly and reproducibly identify changes in disease-associated N-linked glycosylation that are linked with histopathology features in standard formalin-fixed paraffin-embedded tissue samples. It can detect multiple N-glycans simultaneously and has been used to identify specific N-glycans and carbohydrate structural motifs as possible cancer biomarkers. Recent advancements in instrumentation and sample preparation are also discussed. The tissue N-glycan IMS workflow has been adapted to new glass slide-based assays for effective and rapid analysis of clinical biofluids, cultured cells, and immunoarray-captured glycoproteins for detection of changes in glycosylation associated with disease.

Narrative review of urinary glycan biomarkers in prostate cancer

Prostate cancer (PC) is the second most common cancer in men worldwide. The application of the prostate-specific antigen (PSA) test has improved the diagnosis and treatment of PC. However, the PSA test has become associated with overdiagnosis and overtreatment. Therefore, there is an unmet need for novel diagnostic, prognostic, and predictive biomarkers of PC. Urinary glycoproteins and exosomes are a potential source of PC glycan biomarkers. Urinary glycan profiling can provide noninvasive monitoring of tumor heterogeneity and aggressiveness throughout a treatment course. However, urinary glycan profiling is not popular due to technical disadvantages, such as complicated structural analysis that requires specialized expertise. The technological development of glycan analysis is a rapidly advancing field. A lectin-based microarray can detect aberrant glycoproteins in urine, including PSA glycoforms and exosomes. Glycan enrichment beads can enrich the concentration of N-linked glycans specifically. Capillary electrophoresis, liquid chromatography-tandem mass spectrometry, and matrix-assisted laser desorption/ionization-time of flight mass spectrometry can detect glycans directory. Many studies suggest potential of urinary glycoproteins, exosomes, and glycosyltransferases as a biomarker of PC. Although further technological challenges remain, urinary glycan analysis is one of the promising approaches for cancer biomarker discovery.

Outcome of ABO Blood Type-Incompatible Living-Related Donor Kidney Transplantation Under a Contemporary Immunosuppression Strategy in Japan

BACKGROUND

Because of the serious donor shortage in Japan, there is an increasing need for ABO blood type-incompatible kidney transplantation (ABOi-KT) in living-related donor kidney transplantation. We evaluated the outcomes of ABOi-KT performed at our hospitals using a contemporary immunosuppression strategy with low-dose rituximab.

PATIENTS AND METHODS

Between June 2006 and April 2019, 107 patients underwent living-related donor kidney transplantation at our hospitals. The patients were divided into ABO-compatible (ABOc) and ABOi groups. The basic immunosuppression regimen differed between the 2 groups in the use of low-dose rituximab and therapeutic apheresis in the ABOi group. We compared graft survival, patient survival, rejection, viral infection, and posttransplant renal function between the 2 groups.

RESULTS

Of 107 recipients, 37 (35%) underwent ABOi-KT. The 5-year graft survival rates in the ABOc and ABOi group were 91% and 100%, respectively. The Kaplan-Meier analyses showed no difference in graft survival (P = .168) or patient survival (P = .873) between the groups. Biopsy-proven rejection in the ABOc and ABOi groups was observed in 13 (19%) and 7 (19%) patients, respectively (P = .965), and viral infection was observed in 21 (30%) and 10 (27%) patients (P = .747), respectively. Renal function by estimated glomerular filtration rate from 1 week to 5 years after transplantation was similar in both groups.

CONCLUSIONS

The outcomes of ABOi-KT with low-dose rituximab were comparable with those of ABOc-KT at our hospitals. ABOi-KT with proper immunosuppression may be an option to help resolve the severe donor shortage in Japan.

Serum N-glycan profiling can predict biopsy-proven graft rejection after living kidney transplantation

BACKGROUND

To evaluate whether serum N-glycan profile can be used as a diagnostic marker of graft rejection after living-donor kidney transplants (KT).

METHODS

We retrospectively examined 174 KT recipients at five medical centers. N-Glycan levels were analyzed in postoperative serum samples using glycoblotting combined with mass spectrometry. We developed an integrated score to predict graft rejection based on a combination of age, gender, immunological risk factors, and serum N-glycan levels at post-KT day D1 and D7. Rejection-free survival rates stratified by the sum of integrated scores (D1 + D7) were evaluated using Kaplan-Meier curves.

RESULTS

Of 174, 52 showed graft rejection (Rejection-pos. group) and 122 recipients did not show graft rejection (Rejection-neg. group). The integrated scores were significantly higher in the Rejection-pos. group than those of the Rejection-neg. group. Area-under-curve (AUC) value of integrated scores at post-KT D1, and D7 were 0.84 and 0.84, respectively. The sum of integrated scores (D1 + D7) ≥ 0.50 identified graft rejection with 81% sensitivity and 80% specificity; with an AUC value of 0.87. Recipients with higher sum of integrated scores (D1 + D7 ≥ 0.5) had significantly shorter rejection-free survival than those with lower scores.

CONCLUSION

Evaluation of serum N-glycosylation profiles can identify recipients who are prone to rejection.

Mass spectrometry-based qualitative and quantitative N-glycomics: An update of 2017-2018

N-glycosylation is one of the most frequently occurring protein post-translational modifications (PTMs) with broad cellular, physiological and pathological relevance. Mass spectrometry-based N-glycomics has become the state-of-the-art instrumental analytical pipeline for sensitive, high-throughput and comprehensive characterization of N-glycans and N-glycomes. Improvement and new development of methods in N-glycan release, enrichment, derivatization, isotopic labeling, separation, ionization, MS, tandem MS and informatics accompany side-by-side wider and deeper application. This review provides a comprehensive update of mass spectrometry-based qualitative and quantitative N-glycomics in the years of 2017-2018.

Endocan as a marker of microvascular inflammation in kidney transplant recipients

Endocan is a water-soluble proteoglycan exclusively secreted by vascular endothelium. Endocan levels may be elevated in kidney transplant recipients experiencing antibody-mediated rejection (ABMR), which is characterized by vascular inflammation in transplanted kidney. We evaluated the clinical relevance of endocan as markers of microvascular inflammation in patients who underwent kidney transplantation. Plasma and urinary endocan levels were measured in 203 kidney transplant recipients and were compared across different etiologies of allograft dysfunction and various pathologic scores. Both plasma and urinary endocan levels were significantly higher in patients with acute ABMR than those in patients with normal pathology, acute tubular necrosis (ATN), acute pyelonephritis, BK virus associated nephropathy (BKVN), and T-cell mediated rejection (TCMR). Patients with chronic active ABMR also exhibited significantly higher plasma and urinary endocan levels than patients with long-term graft survival. Scores of glomerulitis and peritubular capillaritis, which are typical features of microvascular inflammation, were significantly elevated in patients with higher plasma and/or urinary endocan levels. Furthermore, plasma and urinary endocan levels could effectively discriminate ABMR from ATN, BKVN, and TCMR. Finally, patients exhibiting high urinary and plasma endocan levels in acute ABMR group showed significantly worse renal survival. Altogether, plasma and urinary endocan levels may serve as potential markers of microvascular inflammation in kidney transplant recipients.