The relation of the level of serum anti-TF, -Tn and -alpha-Gal IgG to survival in gastrointestinal cancer patients

Automated glycan-bead coupling for high throughput, highly reproducible anti-glycan antibody analysis

Automation of diagnostic assays generally aims to increase reproducibility and throughput while decreasing human errors and hands-on time. Here, we introduce a protocol for the automated chemical conjugation of glycans to color-coded magnetic beads using the KingFisher Flex magnetic particle processor. The resulting glycan-coupled magnetic beads allow the detection of anti-glycan antibodies of different isotypes from various species. By generating anti-glycan antibody profiles, monoclonal antibodies can be screened for their specificity and cross-reactivity, while anti-glycan antibody profiles from different human body fluids can aid in predicting response to treatment or outcome of disease. This efficient, scalable protocol can also be adapted to attach proteins and other biomolecules to beads, making it useful for a wider range of applications that require bead-based laboratory methods.

Aberrant Glycosylation as Immune Therapeutic Targets for Solid Tumors

Glycosylation occurs at all major types of biomolecules, including proteins, lipids, and RNAs to form glycoproteins, glycolipids, and glycoRNAs in mammalian cells, respectively. The carbohydrate moiety, known as glycans on glycoproteins and glycolipids, is diverse in their compositions and structures. Normal cells have their unique array of glycans or glycome which play pivotal roles in many biological processes. The glycan structures in cancer cells, however, are often altered, some having unique structures which are termed as tumor-associated carbohydrate antigens (TACAs). TACAs as tumor biomarkers are glycan epitopes themselves, or glycoconjugates. Some of those TACAs serve as tumor glyco-biomarkers in clinical practice, while others are the immune therapeutic targets for treatment of cancers. A monoclonal antibody (mAb) to GD2, an intermediate of sialic-acid containing glycosphingolipids, is an example of FDA-approved immune therapy for neuroblastoma indication in young adults and many others. Strategies for targeting the aberrant glycans are currently under development, and some have proceeded to clinical trials. In this review, we summarize the currently established and most promising aberrant glycosylation as therapeutic targets for solid tumors.

Expert Consensus on Diagnosis and Treatment of End-Stage Liver Disease Complicated with Infections

Abstract

End-stage liver disease (ESLD) is a life-threatening clinical syndrome that markedly increases mortality in patients with infections. In patients with ESLD, infections can induce or aggravate the occurrence of liver decompensation. Consequently, infections are among the most common complications of disease progression. There is a lack of working procedure for early diagnosis and appropriate management for patients with ESLD complicated by infections as well as local and international guidelines or consensus. This consensus assembled up-to-date knowledge and experience across Chinese colleagues, providing data on principles as well as working procedures for the diagnosis and treatment of patients with ESLD complicated by infections.

Prospects and Challenges of the Study of Anti-Glycan Antibodies and Microbiota for the Monitoring of Gastrointestinal Cancer

Over the past decades, a large amount of data has been accumulated in various subfields of glycobiology. However, much clinically relevant data and many tools are still not widely used in medicine. Synthetic glycoconjugates with the known structure of glycans are an accurate tool for the study of glycan-binding proteins. We used polyacrylamide glycoconjugates (PGs) including PGs with tumour-associated glycans (TAGs) in immunoassays to assess the prognostic potential of the serum level of anti-glycan antibodies (AG Abs) in gastrointestinal cancer patients and found an association of AG Abs with survival. The specificity of affinity-isolated AG Abs was investigated using synthetic and natural glycoconjugates. AG Abs showed mainly a low specificity to tumour-associated and tumour-derived mucins; therefore, the protective role of the examined circulating AG Abs against cancer remains a challenge. In this review, our findings are analysed and discussed in the context of the contribution of bacteria to the AG Abs stimulus and cancer progression. Examples of the influence of pathogenic bacteria colonising tumours on cancer progression and patient survival through mechanisms of interaction with tumours and dysregulated immune response are considered. The possibilities and problems of the integrative study of AG Abs and the microbiome using high-performance technologies are discussed.

Glycan-specific antibodies as potential cancer biomarkers: a focus on microarray applications

Glycosylation is one of the most common posttranslational modifications of proteins and lipids. In the case of tumors, cell transformation accompanied by aberrant glycosylation results in the expression of tumor-associated glycans that promote tumor invasion. As part of the innate immunity, anti-glycan antibodies recognize tumor-associated glycans, and these antibodies can be present in the bloodstream in the early stages of cancer. Recently, anti-glycan antibody profiles have been of interest in various cancer studies. Novel advantages in the field of analytical techniques have simplified the analysis of anti-glycan antibodies and made it easier to have more comprehensive knowledge about their functions. One of the robust approaches for studying anti-glycan antibodies engages in microarray technology. The analysis of glycan microarrays can provide more expanded information to simultaneously specify or suggest the role of antibodies to a wide variety of glycans in the progression of different diseases, therefore making it possible to identify new biomarkers for diagnosing cancer and/or the state of the disease. Thus, in this review, we discuss antibodies to various glycans, their application for diagnosing cancer and one of the most promising tools for the investigation of these molecules, microarrays.

Anti-glycan antibodies: roles in human disease

Carbohydrate-binding antibodies play diverse and critical roles in human health. Endogenous carbohydrate-binding antibodies that recognize bacterial, fungal, and other microbial carbohydrates prevent systemic infections and help maintain microbiome homeostasis. Anti-glycan antibodies can have both beneficial and detrimental effects. For example, alloantibodies to ABO blood group carbohydrates can help reduce the spread of some infectious diseases, but they also impose limitations for blood transfusions. Antibodies that recognize self-glycans can contribute to autoimmune diseases, such as Guillain-Barre syndrome. In addition to endogenous antibodies that arise through natural processes, a variety of vaccines induce anti-glycan antibodies as a primary mechanism of protection. Some examples of approved carbohydrate-based vaccines that have had a major impact on human health are against pneumococcus, Haemophilus influeanza type b, and Neisseria meningitidis. Monoclonal antibodies specifically targeting pathogen associated or tumor associated carbohydrate antigens (TACAs) are used clinically for both diagnostic and therapeutic purposes. This review aims to highlight some of the well-studied and critically important applications of anti-carbohydrate antibodies.

The Potential Action of Thomsen-Friedenreich Monoclonal Antibody (A78-G/A7) in Thyroid Cancer

Background

Thomsen–Friedenreich antibody (TF-Ab) is a specific antibody against the Thomsen–Friedenreich antigen (TF-Ag). At present, studies on a number of other tumors have shown that TF-Ab can effectively inhibit metastasis and induce apoptosis in tumor cells. However, the role of TF-Ab in thyroid cancer (TC) remains unclear.

Materials and Methods

Normal subjects and patients with primary papillary TC with or without lymph node metastasis were tested for TF-Ab expression by enzyme-linked immunosorbent assays (ELISAs). Immunofluorescence was used to assess the expression of TF-Ag in thyroid papillary carcinoma with or without lymph node metastasis and undifferentiated cancer tissues. To evaluate the role of TF-Ab in TC, the effects of TF monoclonal antibody (mAb A78-G/A7) on cell biological function were investigated by MTT assays, flow cytometry, adhesion assays and transwell experiments.

Results

Compared with normal individuals, TF-Ab levels in patients with TC were decreased, but no changes were observed with respect to lymph node metastasis. The expression of TF-Ag in TC tissues was relatively higher than that detected in adjacent tissues, but it was not affected by the presence or absence of lymph node metastasis. Upon treatment mAb A78-G/A7 treating, TC cell cycles were affected, meanwhile the abilities to adhere, invade and migrate were also significantly reduced.

Conclusion

The results of the present study showed that mAb A78-G/A7 could affect the invasion and migration of all assayed TC cell lines. The effects of mAb A78-G/A7 on the cell cycle, adhesion, invasion and migration of TC cells were more significant than those observed for proliferation and apoptosis.

Antibodies against aberrant glycans as cancer biomarkers

Introduction: The review provides a comprehensive overview about applicability of serological detection of autoantibodies against aberrant glycans as cancer biomarkers.Areas covered: Clinical usefulness of autoantibodies as cancer biomarkers is discussed for seven types of cancers with sensitivity and specificity of such biomarkers provided. Moreover, an option of using serological antibodies against a non-natural form of sialic acid - N-glycolylneuraminic acid (Neu5Gc), which is taken into our bodies together with red meat, as a potential cancer biomarker is discussed shortly as well.Expert opinion: In the final part of the review, we discuss what measures need to be applied for selective implementation of autoantibody assays into a clinical practice. Moreover, we discuss key challenges ahead for reliable and robust detection of autoantibodies against aberrant glycans as biomarkers for disease diagnostics and for stratification of cancer patients.

Purified human anti-Tn and anti-T antibodies specifically recognize carcinoma tissues

Described in several epithelial cancer cells, Tn- (GalNAcα1-O-Ser/Thr) and T- (Galβ3GalNAcα1-O-Ser/Thr) antigens are examples of tumor-associated antigens. Increased expression of Tn- and T-antigens is associated with tumor invasion and metastasis, and patients with high concentration of anti-Tn and anti-T antibodies have a more benign evolution of pathology. Asialofetuin (ASF) and ovine submaxillary mucin (OSM) are two glycoproteins that expose T- and Tn-antigen, respectively. In this work, using ASF or OSM we affinity-purified anti-T and anti-Tn antibodies from normal human plasma and tested their ability to specifically recognize tumor human tissues. Whereas purified anti-T antibodies (purity degree increase of 127-fold, and 22% recovery) were mainly IgG, for purified anti-Tn antibodies (purity degree enhancement of 125-fold, and 26% yield) the IgM fraction was predominant over the IgG one. IgG2 subclass was significantly enriched in both purified antibody samples. Purified antibodies did not bind normal human tissue (0/42), although recognized malignant tissues from different origin such as colon carcinoma (11/77 by anti-Tn; 7/79 by anti-T), breast carcinoma (10/23 by anti-Tn; 7/23 by anti-T), and kidney carcinoma (45/51 by anti-Tn; 42/51 by anti-T). Our results suggest that purified human anti-Tn and anti-T antibodies have a potential as anti-tumor therapeutic agents; restoring their levels in human sera could positively affect the evolution of patients with epithelial tumor pathologies.

IgG Antibodies to GlcNAcβ and Asialo-GM2 (GA2) Glycans as Potential Markers of Liver Damage in Chronic Hepatitis C and the Efficacy of Antiviral Treatment

Total serum IgG level is a surrogate marker of hepatitis C (HC) severity. Antibodies (Abs) to microbial glycans could be markers of HC severity caused by the translocation of microbial products. The level of anti-glycan (AG) Abs was analysed in serum samples of patients (n = 128) with chronic HC in ELISA using fourteen synthetic glycans present in microbes and adhesins to evaluate the association of Abs with clinical parameters and the efficacy of antiviral treatment. The anti-GlcNAcβ IgG level was significantly higher in patients with fibrosis (P = 0.021) and severe portal inflammation (P < 0.001) regardless of other clinical parameters. The ROC curve analysis showed sensitivity of 0.59, specificity of 0.84, and AUC of 0.71 in discriminating F0 from F1–4 (HCV genotype-1b-infected patients). The level of anti-GA2 Abs before Peg-IFN/RBV treatment was significantly higher in nonsustained viral response (non-SVR) to treatment than in SVR (P = 0.033). ROC analysis showed sensitivity of 0.62, specificity of 0.70, and AUC of 64. Correlations of AG Abs to clinical parameters were found. The quantification of anti-GlcNAcβ Abs deserves attention in assessment of the hepatic damage while anti-GA2 Abs may be a sign of immune response related to the antiviral treatment.

The Thomsen-Friedenreich Antigen-Specific Antibody Signatures in Patients with Breast Cancer

Alterations in the glycosylation of serum total immunoglobulins show these antibodies to have a diagnostic potential for cancer but the disease-related Abs to the tumor-associated antigens, including glycans, have still poorly been investigated in this respect. We analysed serum samples from patients with breast carcinoma (n = 196) and controls (n = 64) for the level of Thomsen-Friedenreich (TF) antigen-specific antibody isotypes, their sialylation, interrelationships, and the avidity by using ELISA with the synthetic TF-polyacrylamide conjugate as an antigen and the sialic acid-specific Sambucus nigra agglutinin (SNA) and ammonium thiocyanate as a chaotrope. An increased sialylation of IgG and IgM, but a lower SNA reactivity of IgA TF antibodies, and a higher level and avidity of the TF-specific IgA were found in cancer patients. Other cancer-related signatures were the highly significant increase of the IgG/IgA ratio and the very low SNA/IgA index in cancer, including patients with an early stage of the disease. These changes showed a good diagnostic potential with about 80% accuracy. Thus, the level of naturally occurring anti-TF antigen antibodies, their sialylation profile, isotype distribution, and avidity displayed cancer-specific changes that could serve as novel noninvasive Ab-based biomarkers for early breast cancer.

Serum N-glycome characterization and anti-carbohydrate antibody profiling in oral squamous cell carcinoma patients

Glycosylation is a protein post translational modification which plays important role in protein function, stabilization, trafficking, and turnover. Alteration of protein glycosylation is a common phenomenon during tumor progression, migration, invasion, angiogenesis, as well as metastasis. Hence, aberrant glycan structures and the induced corresponding anti-carbohydrate antibodies are potential biomarkers for cancer diagnosis. In this study, serum N-glycomes and anti-carbohydrate antibodies from normal populations and oral squamous cell carcinoma (OSCC) patients were investigated. Total serum proteins were lyophilized and subjected to chemical reduction, alkylation and trypsin digestion. The N-glycans were released, purified, permethylated, and analyzed using MALDI-TOF-Mass spectrometry. In addition, the serum anti-carbohydrate antibody profiles were also investigated by carbohydrate microarray. We found that the relative abundances of seven N-glycans were decreased or increased in serum of OSCC with diagnostic accuracy greater than 75%. The relative abundances of total tri-antennary and tetra-antennary glycans with varying degrees of fucosylation and sialylation were also increased in serum N-glycomes of OSCC. In an independent validation group of forty-eight OCCC patients, most of the high-molecular weight serum N-glycans showed significantly high sensitivity and specificity according to the identified cutoff values. Furthermore, the serum levels of two IgM antibodies were elevated accompanied with the decreased levels of nine IgG antibodies in patient serum. Taken together, these serum N-glycans and antibodies identified in this study should be considered as the candidates of potential biomarkers for OSCC diagnosis.

Hidden IgG Antibodies to the Tumor-Associated Thomsen-Friedenreich Antigen in Gastric Cancer Patients: Lectin Reactivity, Avidity, and Clinical Relevance

Natural antibodies to the tumor-associated Thomsen-Friedenreich antigen (TF) are related to tumor immunosurveillance and cancer patients' survival. Hidden IgG antibodies (HAbs) to TF, their lectin reactivity, avidity, and clinical relevance were studied. HAbs were present in cancer patients and controls. A decreased level of IgG HAbs was detected in cancer. The HAbs level positively correlated with the sialospecific SNA lectin binding in purified total IgG (tIgG) in donors and cancer patients, indicating that HAbs are higher sialylated. The avidity of anti-TF IgG in tIgG samples was lower in cancer patients (P = 0.025) while no difference in the avidity of free anti-TF IgG was established. A negative correlation between the avidity of anti-TF IgG in tIgG and SNA binding in both groups was observed (P < 0.0001). The HAbs level negatively correlated with the anti-TF IgG avidity in tIgG only in donors (P = 0.003). Changes in the level of HAbs and Abs avidity showed a rather good stage- and gender-dependent diagnostic accuracy. Cancer patients with a lower anti-TF IgG avidity in tIgG showed a benefit in survival. Thus the TF-specific HAbs represent a particular subset of anti-TF IgG that differ from free serum anti-TF IgG in SNA reactivity, avidity, diagnostic potential, and relation to survival.

Impact of oral consumption of heat-treated Bacteroides xylanisolvens DSM 23964 on the level of natural TFα-specific antibodies in human adults

It is now generally accepted that the human body exists in close synergy with the gut microbiome and that this cross-talk plays an essential role in human health and disease. One facet from the many interactions between the microbiome and the immune system is the induction of natural antibodies to commensal bacterial glycans, such as blood group antigens, the alpha-Gal epitope or the Thomsen-Friedenreich (TFα) antigen. Since we have observed that certain species of the commensal genus Bacteroides express the TFα antigen, we examined whether the oral dietary supplementation of a pasteurised Bacteroides xylanisolvens strain might be able to enhance the level of natural anti-TFα antibodies in healthy adults. The data obtained from a double-blind, placebo-controlled study involving 140 healthy volunteers and lasting 8 weeks revealed that the oral uptake of this strain was indeed able to increase the level of TFα-specific immunoglobulin M serum antibodies. The effect was dose-dependent but remained – at any doses – within the physiological range determined before intervention. Furthermore, the effect reverted after stopping the intake. The results support the idea of the microbiome inducing the generation of systemic antigen-specific antibodies against sugar epitopes. They also demonstrate the possibility to modulate essential regulatory or defence processes through dietary supplementation of selected commensal bacteria with the aim to assist human health.

Increased Avidity of the Sambucus nigra Lectin-Reactive Antibodies to the Thomsen-Friedenreich Antigen as a Potential Biomarker for Gastric Cancer

AIM

To determine whether the naturally occurring Thomsen-Friedenreich (TF) antigen-specific antibodies differ in avidity between cancer patients and controls to find a novel biomarker for stomach cancer.

METHODS

Serum samples were taken from patients with cancer and controls. The level of TF-specific antibodies and their sialylation were determined using ELISA with synthetic TF-polyacrylamide conjugate as antigen and sialic acid-specific Sambucus nigra agglutinin (SNA). The avidity was determined using ammonium thiocyanate as a chaotrope.

RESULTS

A significantly higher SNA lectin binding to anti-TF antibodies was found in cancer patients irrespective of disease stage. The avidity of only IgM TF-specific antibodies was significantly higher in cancer patients compared to controls. The SNA-positive anti-TF antibodies of cancer patients showed a significantly higher avidity, P < 0.001. The sensitivity and specificity of this increase for gastric cancer were 73.53% and 73.08%, respectively, with a 73.2% diagnostic accuracy. The higher avidity of SNA-reactive anti-TF antibodies was associated with a benefit in survival of stage 3 cancer patients.

CONCLUSION

The SNA-reactive TF-specific antibodies display a significantly higher avidity in gastric cancer patients compared to controls, which can be used as a potential serologic biomarker for gastric cancer. It appears that IgM is the main target responsible for the above changes.