Avian influenza virus infection risk in humans with chronic diseases

Respiratory tract barrier dysfunction in viral-bacterial co-infection cases

A preceding viral infection of the respiratory tract predisposes the host to secondary bacterial pneumonia, known as a major cause of morbidity and mortality. However, the underlying mechanism of the viral-bacterial synergy that leads to disease progression has remained elusive, thus hampering the production of effective prophylactic and therapeutic intervention options. In addition to viral-induced airway epithelial damage, which allows dissemination of bacteria to the lower respiratory tract and increases their invasiveness, dysfunction of immune defense following a viral infection has been implicated as a factor for enhanced susceptibility to secondary bacterial infections. Given the proximity of the oral cavity to the respiratory tract, where viruses enter and replicate, it is also well-established that oral health status can significantly influence the initiation, progression, and pathology of respiratory viral infections. This review was conducted to focus on the dysfunction of the respiratory barrier, which plays a crucial role in providing physical and secretory barriers as well as immune defense in the context of viral-bacterial synergy. Greater understanding of barrier response to viral-bacterial co-infections, will ultimately lead to development of effective, broad-spectrum therapeutic approaches for prevention of enhanced susceptibility to these pathogens.

Evaluation of salivary glycopatterns based diagnostic models for prediction of diabetic vascular complications

Diabetic vascular complications (DVC) are the main cause of death in diabetic patients. However, there is a lack of effective biomarkers or convenient methods for early diagnosis of DVC. In this study, the salivary glycopatterns from 130 of healthy volunteers (HV), 139 patients with type 2 diabetes mellitus (T2DM) and 167 patients with DVC were case-by-case analyzed by using lectin microarrays. Subsequently, diagnostic models were developed using logistic regression and machine learning algorithms based on the data of lectin microarrays in training set. The performance of diagnostic models was evaluated in an independent blind cohort. The results of lectin microarrays indicated that the glycopatterns identified by 16 lectins (e.g. BS-I, PWM and EEL) were significantly altered in DVC patients compared with patients with T2DM, which suggested the alterations in salivary glycopatterns could reflect onset of DVC. Notably, K-Nearest Neighbor (KNN) model exhibited better performance for distinguishing DVC (accuracy: 0.939) than other models in blind cohort. The integrated classifier, which combined three machine learning models, exhibited a higher overall accuracy (≥ 0.933) than other models in blind cohort. Our study provided a cost-effective and non-invasive method for auxiliary diagnosis DVC based on the combination of salivary glycopatterns and machine learning algorithms.

N-Glycan Profiles of Neuraminidase from Avian Influenza Viruses

The cleavage of sialic acids by neuraminidase (NA) facilitates the spread of influenza A virus (IV) descendants. Understanding the enzymatic activity of NA aids research into the transmission of IVs. An effective method for purifying NA was developed using p-aminophenyloxamic acid-modified functionalized hydroxylated magnetic particles (AAMPs), and from 0.299 to 0.401 mg of NA from eight IV strains was isolated by 1 mg AAMP. A combination of lectin microarrays and MALDI-TOF/TOF-MS was employed to investigate the N-glycans of isolated NAs. We found that more than 20 N-glycans were identified, and 16 glycan peaks were identical in the strains derived from chicken embryo cultivation. Multi-antennae, bisected, or core-fucosylated N-glycans are common in all the NAs. The terminal residues of N-glycans are predominantly composed of galactose and N-acetylglucosamine residues. Meanwhile, sialic acid residue was uncommon in these N-glycans. Further computational docking analysis predicted the interaction mechanism between NA and p-aminophenyloxamic acid.

Salivary Proteome and Intact N-Glycopeptides Analysis Reveal Specific Signatures in Periodontitis

Periodontitis is a prevalent oral inflammatory disease that can result in tooth loss and is closely linked to type 2 diabetes (T2D). In this study, we analyzed the salivary proteome and intact N-glycopeptides (IGPs) of individuals with mild-moderate, severe, aggressive periodontitis, and periodontitis with T2D, including those treated with antidiabetic drugs, to identify specific signatures associated with the disease. Our results revealed that salivary proteins and glycoproteins were altered in all periodontitis groups (PRIDE ID: 1-20230612-72345), with fucose- and sialic acid-containing N-glycans showing the greatest increase. Additionally, differentially expressed proteins were classified into 9 clusters, including those that were increased in all periodontitis groups and those that were only altered in certain types of periodontitis. Interestingly, treatment with antidiabetic drugs reversed many of the changes observed in the salivary proteome and IGPs in T2D-related periodontitis, suggesting a potential therapeutic approach for managing periodontitis in patients with T2D. Consistent with MS/MS results, the expression of salivary IGHA2 and Fucα1-3/6GlcNAc (AAL) was significantly increased in MP. These findings provide new insights into the pathogenesis of periodontitis and highlight the potential of salivary biomarkers for diagnosis, prognosis, and monitoring of disease progression and treatment response.

Beneficial or detrimental: Recruiting more types of benign cases for cancer diagnosis based on salivary glycopatterns

With the advantages of convenient, painless and non-invasive collection, saliva holds great promise as a valuable biomarker source for cancer detection, pathological assessment and therapeutic monitoring. Salivary glycopatterns have shown significant potential for cancer screening in recent years. However, the understanding of benign lesions at non-cancerous sites in cancer diagnosis has been overlooked. Clarifying the influence of benign lesions on salivary glycopatterns and cancer screening is crucial for advancing the development of salivary glycopattern-based diagnostics. In this study, 2885 samples were analyzed using lectin microarrays to identify variations in salivary glycopatterns according to the number, location, and type of lesions. By utilizing our previously published data of tumor-associated salivary glycopatterns, the performance of machine learning algorithm for cancer screening was investigated to evaluate the effect of adding benign disease cases to the control group. The results demonstrated that both the location and number of lesions had discernible effects on salivary glycopatterns. And it was also revealed that incorporating a broad range of benign diseases into the controls improved the classifier's performance in distinguishing cancer cases from controls. This finding holds guiding significance for enhancing salivary glycopattern-based cancer screening and facilitates their practical implementation in clinical settings.

A novel strategy for quantification of α2,3- and α2,6-linked sialic acids in sialylated glycoproteins

Sialic acid, a monosaccharide containing nine carbon atoms, is widely distributed in eukaryotic cells. The bound sialic acids are mainly present at the glycan ends of glycoconjugates via α2-3 or α2-6 glycosidic bonds, and alterations in their expression levels and linkage types are associated with the progress of many diseases and tumors. The present study provides a new strategy for quantification of α2,3- and α2,6-linked sialic acids in sialylated glycoproteins. In fact, quantification of α2,3-linked sialic acids were based on the difference of the bound sialic acids in the sample before and after treatment with α2-3 neuraminidase, whereas the α2,6-linked sialic acids were equal to the bound sialic acids in the α2-3 neuraminidase-treated sample. Subsequently, α2,3/6-linked sialic acids in salivary glycoproteins from healthy volunteers and diabetic patients were quantified in accordance with this method. This work provides an accurate method for the quantification of α2,3- and α2,6-linked sialic acids in the sialoglycoproteins, which is more instructive for understanding the biological roles of α2,3/6-linked sialic acid in sialoglycoproteins.

High Expression Level of α2-3-Linked Sialic Acids on Salivary Glycoproteins of Breastfeeding Women May Help to Protect Them from Avian Influenza Virus Infection

Terminal sialic acids (Sia) on soluble glycoprotein of saliva play an important role in the clearance of influenza virus. The aim of this study is to investigate the alteration of sialylation on the salivary proteins of women during the lactation period and its effect on the saliva binding ability to virus. In total, 210 saliva samples from postpartum women with and without breastfeeding were collected, and the expression level of α2-3/6-linked Sia on the whole salivary proteins and specific glycoproteins of IgA and MUC5B from different groups were tested and verified using lectin microarray, blotting analysis and ELISA based method. The H1N1 vaccine and three strains of Avian influenza virus (AIV) were used for the saliva binding assay. Results showed that the variation in salivary expression level of α2-3-linked Sia was much more obvious than the α2-6-linked Sia, which was up-regulated significantly in the breastfeeding groups compared to the non-breastfeeding groups at the same postpartum stage. Furthermore, the binding abilities of salivary glycoproteins to AIV strains and H1N1 vaccine were increased in breastfeeding groups accordingly. This finding adds new evidence for the maternal benefit of breastfeeding and provides new thinking to protect postpartum women from AIV infection.

Elevation of α-1,3 fucosylation promotes the binding ability of TNFR1 to TNF-α and contributes to osteoarthritic cartilage destruction and apoptosis

Background

Osteoarthritis (OA) is the most common form of arthritis and is characterized by the degradation of articular cartilage and inflammation of the synovial membrane. Fucosylation is an important feature of protein N/O-glycosylation and is involved in a variety of pathological processes, including inflammation and cancer. However, whether fucosylation impacts the OA pathological process is unknown.

Methods

Total proteins were extracted from cartilage samples obtained from patients with OA (n = 11) and OA rabbit models at different time points (n = 12). OA-associated abnormal glycopatterns were evaluated by lectin microarrays and lectin blots. The expression of fucosyltransferases involved in the synthesis of α-1,3 fucosylation was assessed by semi-qPCR. The synthesis of α-1,3 fucosylation mediated by FUT10 was interrupted by the transfection of siRNA, and the effect of α-1,3 fucosylation on OA-associated events was assessed. Then, immunoprecipitation and lectin blotting were used to investigate the relationship between the α-1,3 fucosylation level of tumor necrosis factor receptor superfamily member 1A (TNFR1) and OA. Finally, a TNFR1 antibody microarray was fabricated to evaluate the effect of α-1,3 fucosylation on the ability of TNFR1 to bind to tumor necrosis factor-α (TNF-α).

Results

Elevated α-1,3 fucosylation was observed in cartilage from OA patients, rabbit models, and chondrocytes induced by TNF-α (fold change> 2, p< 0.01). Our results and the GEO database indicated that the overexpression of FUT10 contributed to this alteration. Silencing the expression of FUT10 impaired the ability of TNFR1 to bind to TNF-α, impeded activation of the NF-κB and P38/JNK-MAPK pathways, and eventually retarded extracellular matrix (ECM) degradation, senescence, and apoptosis in chondrocytes exposed to TNF-α.

Conclusion

The elevation of α-1,3 fucosylation is not only a characteristic of OA but also impacts the OA pathological process. Our work provides a new positive feedback loop of “inflammation conditions/TNF-α/FUT10/α-1,3 fucosylation of TNFR1/NF-κB and P38/JNK-MAPK pathways/proinflammatory processes” that contributes to ECM degradation and chondrocyte apoptosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02776-z.

Pregnancy-associated decrease of Siaα2-3Gal-linked glycans on salivary glycoproteins affects their binding ability to avian influenza virus

Salivary glycoproteins are known as an important barrier to inhibit influenza infection by presenting sialic acid (Sia) ligands that can bind with viral hemagglutination. Here, to further understand why pregnant women are more vulnerable to avian influenza virus (AIV), we investigated the alteration of protein sialylation in the saliva of women during pregnancy and postpartum, and its impact on the saliva binding affinity to AIV. Totally 1200 saliva samples were collected, the expression levels of terminal α2-3/6-linked Sia on salivary proteins were tested and validated, and the binding activities of salivary proteins were assessed against 3 strains of AIV and the H1N1 vaccine. Result showed that the expression of terminal α2-3-linked Sia in the saliva of women decreased dramatically during pregnancy compared to that of non-pregnancy control, especially for women in the second or third trimester (fold change = 0.53 and 0.37, p < 0.001). And their salivary protein binding ability to AIV declined accordingly. The variation of terminal α2-3-linked Sia on salivary MUC5B and IgA was consistent with the above results. This study indicates that the decrease of terminal α2-3-linked Sia on salivary glycoproteins of pregnant women affects their binding ability to AIV, which may provide new insights into AIV prevention and control.

The Impact of Oral Health on Respiratory Viral Infection

Influenza virus and severe acute respiratory syndrome coronavirus (SARS-CoV-2) have caused respiratory diseases worldwide. Coronavirus disease 2019 (COVID-19) is now a global health concern requiring emergent measures. These viruses enter the human body through the oral cavity and infect respiratory cells. Since the oral cavity has a complex microbiota, influence of oral bacteria on respiratory virus infection is considered. Saliva has immune molecules which work as the front line in the biophylactic mechanism and has considerable influence on the incidence and progression of respiratory viral infection. Salivary scavenger molecules, such as gp340 and sialic acid, have been reported to exert anti-influenza virus activity. Salivary secretory immunoglobulin A (SIgA) has potential to acquire immunity against these viruses. Biological features of the oral cavity are thought to affect viral infection in respiratory organs in various ways. In this review, we reviewed the literature addressing the impact of oral conditions on respiratory infectious diseases caused by viruses.

Integrated glycomics strategy for the evaluation of glycosylation alterations in salivary proteins associated with type 2 diabetes mellitus

Glycosylation is involved in several biological processes, and its alterations can reflect the process of certain diseases. Type 2 diabetes mellitus (T2DM) has attained the status of a global pandemic; however, the difference in salivary protein glycosylation between healthy subjects and patients with T2DM has not been fully understood. In the present study, salivary specimens from patients with T2DM (n = 72) and healthy volunteers (HVs, n = 80) were enrolled and divided into discovery and validation cohorts. A method combining the lectin microarray and lectin blotting was employed to investigate and confirm the altered glycopatterns in salivary glycoproteins. Then, lectin-mediated affinity capture of glycoproteins and MALDI-TOF/TOF-MS were performed to obtain the precise structural information of the altered glycans. As a result, the glycopatterns recognized by 5 lectins (LEL, VVA, Jacalin, RCA120 and DSA) showed significant alteration in the saliva of T2DM patients. Notably, the glycopattern of Galβ-1,4GlcNAc (LacNAc) recognized by LEL exhibited a significant increase in T2DM patients compared to HVs in both discovery and validation cohorts. The MALDI-TOF/TOF-MS results indicated that there were 10 and 7 LacNAc-containing N/O-glycans (e.g. m/z 1647.586, 11 688.613 and 1562.470) that were identified only in T2DM patients. Besides, the relative abundance of 3 LacNAc-containing N-glycans and 10 LacNAc-containing O-glycans showed an increase in the glycopattern in T2DM patients. These results indicated that the glycopattern of LacNAc is increased in salivary glycoproteins from T2DM patients, and an increase in LacNAc-containing N/O-glycans may contribute to this alteration. Our findings provide useful information to understand the complex physiological changes in the T2DM patients.

Lectin microarrays for glycoproteomics: an overview of their use and potential

Introduction: Glycoproteomics is an important subdiscipline of proteomics, focusing on the role of protein glycosylation in various biological processes. Protein glycosylation is the enzymatic addition of sugars or oligosaccharides to proteins. Altered glycosylation often occurs in the early stages of disease development, for example, certain tumor-associated glycans have been shown to be expressed in precursor lesions of different types of cancer, making them powerful early diagnostic markers. Lectin microarrays have become a powerful tool for both the study of glycosylation and the diagnosis of various diseases including cancer.Areas covered: This review will discuss the most useful features of lectin microarrays, such as their technological advances, their capability for parallel/high-throughput analysis for the important glycopatterns of glycoprotein, and an overview of their use for glycosylation analysis of various complex protein samples, as well as their diagnostic potential in various diseases.Expert opinion: Lectin microarrays have proved to be useful in studying multiple lectin-glycan interactions in a single experiment and, with the advances made in the field, hold a promise of enabling glycopatterns of diseases in a fast and efficient manner. Lectin microarrays will become increasingly powerful early diagnostic tool for a variety of conditions.

MyoD1 suppresses cell migration and invasion by inhibiting FUT4 transcription in human gastric cancer cells

Myogenic differentiation 1 (MyoD1) is a transcription factor that promotes expression of muscle-specific genes. MyoD1 is expressed at significantly lower levels in gastric cancer (GC) tissues and cells, and it induces apoptosis in GC cells. However, functions for MyoD1 in GC cell migration and gene expression have not been documented. We show that knockdown of MyoD1 promoted migration and invasion of GC cells, whereas MyoD1 overexpression suppressed migration and invasion. We performed chromatin immunoprecipitation (ChIP)-sequencing to identify MyoD1 target genes in MKN-45 cells. The 2-kb upstream regions (Up2k) of the transcription start sites of 57 genes were probably bound by MyoD1. Six of these genes function in signaling pathways such as synthesis of glycosphingolipid biosynthesis—lacto and neolacto series. MyoD1 inhibited transcription of fucosyltransferase IV (FUT4) by binding directly to the FUT4 F3; this finding was validated by ChIP-quantitative PCR and a luciferase reporter assay. Ulex europaeus agglutinin I, which binds Fucα1-2Galβ1-4GlcNAc, and Lewis antigens showed decreased binding to the plasma membrane of cells that overexpressed MyoD1. Knockdown of FUT4 mimicked MyoD1 overexpression by suppressing GC cell migration and invasion; this result implied that MyoD1 suppressed cell migration and invasion via inhibiting the FUT4/matrix metallopeptidase signaling pathway. In summary, this study demonstrated that MyoD1 suppresses migration and invasion of GC cells by directly binding to the F3 region in the FUT4 Up2k and inhibiting FUT4/type II Lewis antigen expression.

High expression levels of influenza virus receptors in airway of the HBV-transgenic mice

In the human population, influenza A viruses are associated with acute respiratory illness and are responsible for millions of deaths annually. Avian and human influenza viruses typically have a different α2-3- and α2-6-linked sialic acid (SA) binding preference. Only a few amino acid changes in the haemagglutinin on the surface of avian influenza viruses (AIV) can cause a switch from avian to human receptor specificity, and the individuals with pathognostic chronic diseases might be more susceptible to AIV due to the decreased expression level of terminal α2-3-linked SA in their saliva. Here, using lectin and virus histochemical staining, we observed the higher expression levels of α2-3/6-linked SA influenza virus receptors in the airway of HBV-transgenic mice compared with that of control mice due to the significant decrease in control mice during ageing, which imply that this is also a risk factor for individuals with pathognostic chronic diseases susceptible to influenza viruses. Our findings will help understand the impact on influenza virus pathogenesis and transmission.

Analysis of Glycosphingolipid Glycans by Lectin Microarrays

Glycosphingolipids (GSLs) are ubiquitous glycoconjugates of cell membranes. Identification of unknown GSL-glycan structures is still a major challenge. To address this challenge, we developed a novel strategy for analysis of GSL-glycans from cultured cells based on a lectin microarray that can directly detect and reveal glycopatterns of GSL extracts without the need for glycan release. There were six steps to perform the analysis of GSL-glycans: (i) extraction of GSLs from cell pellets, (ii) quantification of GSL-glycans using orcinol-sulfuric acid reaction, (iii) preparation of lyso-GSLs by using sphingolipid ceramide N-deacylase, (iv) fluorescence labeling of lyso-GSLs, (v) detection by a lectin microarray, (vi) data acquisition and analysis. Simultaneously, a supplementary verification analysis for GSL-glycans was performed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Optimized experimental conditions, which consisted of the blocking buffer, incubation buffer, and appropriate GSL concentration, were investigated by analyzing the glycopatterns of a standard ganglioside (GM1a) via lectin microarray. The analysis of GSL-glycans from human hepatocarcinoma cell lines (MHCC97L, MHCC97H, and HCCLM3) showed that there were 27 lectins (e.g., WFA, MAL-II, and LTL) to give significantly different signals compared with a normal human liver cell line (HL-7702), indicating up- and/or down-regulations of corresponding glycopatterns such as α1-2 fucosylation and α2-3 sialylation, and changes of certain glycostructures such as Galβ1-3GalNAcβ1-4(NeuAcα2-3)Galβ1-4Glc:Cer and GalNAcα1-3(Fucα1-2)Galβ1-3GlcNAcβ1-3Galβ1-4Glc:Cer. The lectin microarray analysis of lyso-GSLs labeled by fluorescence has proven to be credible, which can provide the glycopatterns and detailed linkage information on GSL-glycans.

Integrated Glycome Strategy for Characterization of Aberrant LacNAc Contained N-Glycans Associated With Gastric Carcinoma

Aberrant glycosylation is not only a feature of malignant cell transformation, but also plays an important role in metastasis. In the present study, an integrated strategy combining the lectin microarrays and lectin cytochemistry was employed to investigate and verify the altered glycopatterns in gastric cancer (GC) cell lines as well as resected tumor specimens from matched tissue sets of 46 GC patients. Subsequently, lectin-mediated affinity capture glycoproteins, and MALDI-TOF/TOF-MS were employed to further acquire precise structural information of the altered glycans. According to the results, the glycopatterns recognized by 10 (e.g., ACA, MAL-I, and ConA) and 3 lectins (PNA, MAL-I, and VVA) showed significantly variations in GC cells and tissue compared to their corresponding controls, respectively. Notably, the relative abundance of Galβ-1,4GlcNAc (LacNAc) recognized by MAL-I exhibited a significant increase in GC cells (p < 0.001) and tissue from patients at stage II and III (p < 0.05), and a significant increase in lymph node positive tumor cases, compared with lymph node negative tumor cases (p < 0.05). More LacNAc contained N-glycans were characterized in tumor sample with advanced stage compared to corresponding control. Moreover, there were 10 neo-LacNAc-contained N-glycans (e.g., m/z 1625.605, 1803.652, and 1914.671) only presented in GC tissue with advanced stage. Among these, six N-glycans were modified with sialic acid or fucose based on LacNAc to form sialylated N-glycans or lewis antigens, respectively. Our results revealed that the aberrant expression of LacNAc is a characteristic of GC, and LacNAc may serve as a scaffold to be further modified with sialic acid or fucose. Our findings provided useful information for us to understand the development of GC.

Identification of abnormal fucosylated-glycans recognized by LTL in saliva of HBV-induced chronic hepatitis, cirrhosis, and hepatocellular carcinoma

The hepatitis B virus (HBV)-induced chronic liver diseases are serious health threats worldwide. There is evidence to display the alterations of salivary N-linked glycans related to the development of HBV-infected liver diseases. Here, we further investigated the alterations of fucosylated N/O-glycans recognized by LTL in saliva from 120 subjects (30 healthy volunteers (HV), 30 patients with hepatitis B (HB), 30 patients with hepatic cirrhosis (HC), and 30 patients with hepatocellular carcinoma (HCC)) using salivary microarrys and MALDI-TOF/TOF-MS. The results showed that the expression level of fucosylated glycans recognized by LTL was significantly increased in HCC compared with other subjects (P < 0.0001). Besides, the fucosylated glycoproteins were isolated from pooled saliva of HV, HB, HC, and HCC by LTL-magnetic particle conjugates. Then, N/O- glycans were released from the isolated glycoproteins with PNGase F and NaClO, and were identified by MALDI-TOF-MS, respectively. Totally, there were 21/20, 25/18, 29/19, and 28/24 N/O-glycan peaks that were identified and annotated with proposed structures in saliva of HV, HB, HC, and HCC. Among the total, there were 8 N-glycan peaks (e.g., m/z 1905.634, 2158.777 and 2905.036) and 15 O-glycan peaks (e.g., 1177.407, 1308.444 and 1322.444) that only presented in patients with HBV-induced liver diseases. One N-glycan peak (m/z 2205.766) was unique in HC, and 9 O-glycan peaks (e.g., m/z 1157.420, 1163.417 and 1193.402) were unique in HCC. This study could facilitate the discovery of biomarkers for HC and HCC based on precise alterations of fucosylated N/O-glycans in saliva.

The Function of Fucosylation in Progression of Lung Cancer

Lung cancer is a disease that influences human health and has become a leading cause of cancer mortality worldwide. However, it is frequently diagnosed at the advanced stage. It is necessary by means of biology to identify specific lung tumor biomarkers with high sensitivity. Glycosylation is one of the most important post-translational modifications and is related to many different diseases. It is involved in numerous essential biological processes, such as cell proliferation, differentiation, migration, cell-cell integrity and recognition, and immune modulation. However, little was known about deregulation of glycosylation in lung cancer and contribution to tumor–microenvironment interactions. Among the numerous glycosylations, fucosylation is the most common modification of glycoproteins and glycosylated oligosaccharides. Increased levels of fucosylation have been detected in various pathological conditions, as well as in lung cancer. In this article, we reviewed the role of fucosylation in lung cancer. We highlighted some of the fucosylation alterations currently being pursued in sera or tissues of lung cancer patients. Moreover, we elaborated on the regulation mechanism of fucosylation in proliferative invasion and metastasis of lung tumor cells. In summary, alterations in fucosylation provide potential biomarkers and therapeutic targets in lung cancer.

Alteration of glycosylation in serum proteins: a new potential indicator to distinguish non-diabetic renal diseases from diabetic nephropathy

Diabetic nephropathy (DN) and nondiabetic renal disease (NDRD) are two major categories of renal diseases in diabetes mellitus patients. The clinical differentiation among them is usually not so clear and effective. In this study, sera from DN and NDRD patients were collected, and glycan profiles of serum proteins from DN and NDRD patients were investigated and compared by using lectin microarray and lectin blot. Then, altered glycoproteins were enriched by lectin coupled magnetic particle conjugate and characterized by LC-MS/MS. We found significant change in glycan patterns between DN and NDRD patients. In particular, the relative abundance of the glycopattern of Galβ1-3GalNAc which was identified by BPL (Bauhinia purpurea lectin) was significantly decreased in DN patients compared to four types of NDRD patients (p < 0.05). Moreover, BPL blotting indicated that the proteins with a molecular weight of about 53 kDa exhibited low staining signal in DN compared to all NDRD groups, which was consistent with results of lectin microarrays. After enriching by BPL and identification by LC-MS/MS, a total of 235 and 258 proteins were characterized from NDRD and DN respectively. Among these, the relative abundance of 12 isolated serum proteins exhibited significantly alteration between DN and NDRD (p < 0.05). Our findings indicated not only the relative abundance of Galβ1-3GalNAc on serum proteins but also certain glycoproteins modified with this glycopattern showed a difference between DN and NDRD patients. This suggested that the analysis of this alteration by using urine specimens may constitute an additional valuable diagnostic tool for differentiating DN and NDRD with a non-invasive method.

Identification of N- and O-linked glycans recognized by AAL in saliva of patients with atrophic gastritis and gastric cancer

BACKGROUND AND AIM

Gastric cancer (GC) is a common and fatal malignancy with a worldwide occurrence. There still lacks effective biomarkers for precisely evaluating GC. Saliva is a biological fluid with enormous diagnostic potentials which emerged many advantages. We aimed to discover the novel biomarkers for accurately distinguishing early GC based on saliva glycopatterns.

METHODS

We used Aleuria Aurantia Lectin (AAL)-magnetic particle conjugates to isolate fucosylated glycoproteins in the pooled saliva of healthy volunteers (HV, n= 51) and patients with atrophic gastritis (AG, n= 51) or GC (n= 51), following to release the N- and O-linked glycans from the isolated proteins with PNGase F and NaClO, and further identified the released glycans by MALDI-TOF/TOF-MS, respectively.

RESULTS

A total of 9/9, 8/11, and 9/9 fucosylated N-/O-linked glycans were annotated in the isolated salivary proteins from HV, AG, and GC, respectively. Among these, six fucosylated N-linked glycansand four O-linked glycans exhibited significantly increased expression levels in GC, while five fucosylated N-linked glycans and ten fucosylated O-linked glycans exhibited significantly decreased expression levels in GC. The proportion of fucosylated N-linked glycans was decreased in GC (41.66%) compared with AG (43.63%) and HV (52.57%), as well as the fucosylated O-linked glycans was apparently decreased in GC (19.58%) compared with AG (25.43%) and HV (55.54%).

CONCLUSIONS

This study could provide pivotal information to distinguish among HV, AG, and GC, and facilitate the discovery of biomarkers for GC diagnosis based on precise alterations of N- and O-linked glycans in saliva.

Lectin microarray and mass spectrometric analysis of hepatitis C proteins reveals N-linked glycosylation

We used lectin microarray and mass spectrometric analysis to identify the N-linked glycosylation patterns of hepatitis C virus (HCV) particles. HCV J6/JFH-1 chimeric cell culture (HCVcc) in the culture supernatant was concentrated and purified by ultrafiltration and sucrose gradient ultracentrifugation. Twelve fractions were collected from the top and analyzed for viral infectivity and HCV RNA content after sucrose gradient separation. HCV RNA and proteins were separated by ultracentrifugation in a continuous 10% to 60% sucrose gradient to purify viral particles based on their sedimentation velocities. HCVcc particles were found mainly in fractions 6 to 8, as determined by quantitative polymerase chain reaction (qPCR) analysis for HCV RNA and ELISA of the HCV core protein. The N-glycans on HCV proteins were analyzed by lectin microarray and mass spectrometry. We identified that 32 of 37 lectins displayed the positive binding signals and 16 types of N-glycoforms of which the major HCV glycoforms were high mannose-type N-linked oligosaccharides, hybrid N-glycans, and fucosylated N-glycans. Our study provided new detailed information regarding the majority of the glycan-protein profile, complementing to previous findings of glycan-HCV protein interactions.

Salivary glycopatterns as potential biomarkers for diagnosis of gastric cancer

Gastric cancer (GC) is still an extremely severe health issue with high mortality due to the lacking of effective biomarkers. In this study, we aimed to investigate the alterations of salivary protein glycosylation related to GC and assess the possibility of salivary glycopatterns as potential biomarkers for the diagnosis of GC. Firstly, 94 patients with GC (n = 64) and atrophic gastritis (AG) (n = 30), as well as 30 age- and sex-matched healthy volunteers (HV) were enrolled in the test group to probe the difference of salivary glycopatterns using lectin microarrays, the results were validated by saliva microarrays and lectin blotting analysis. Then, the diagnostic model of GC (Model GC) and AG (Model AG) were constructed based on 15 candidate lectins which exhibited significant alterations of salivary glycopattern by logistic stepwise regression. Finally, two diagnostic models were assessed in the validation group including HV (n = 30) and patients with GC (n = 23) and AG (n = 24) and achieved high diagnostic power (Model GC (AUC: 0.89, sensitivity: 0.96 and specificity: 0.80), Model AG (AUC: 0.83, sensitivity: 0.92 and specificity: 0.72)). This study provides pivotal information to distinguish HV, AG and GC based on precise alterations in salivary glycopatterns, which have great potential to be biomarkers for diagnosis of GC.

Salivary Glycopatterns as Potential Biomarkers for Screening of Early-Stage Breast Cancer

OBJECTIVE

We systematically investigated and assessed the alterations of salivary glycopatterns and possibility as biomarkers for diagnosis of early-stage breast cancer.

DESIGN

Alterations of salivary glycopatterns were probed using lectin microarrays and blotting analysis from 337 patients with breast benign cyst or tumor (BB) or breast cancer (I/II stage) and 110 healthy humans. Their diagnostic models were constructed by a logistic stepwise regression in the retrospective cohort. Then, the performance of the diagnostic models were assessed by ROC analysis in the validation cohort. Finally, a double-blind cohort was tested to confirm the application potential of the diagnostic models.

RESULTS

The diagnostic models were constructed based on 9 candidate lectins (e.g., PHA-E+L, BS-I, and NPA) that exhibited significant alterations of salivary glycopatterns, which achieved better diagnostic powers with an AUC value >0.750 (p<0.001) for the diagnosis of BB (AUC: 0.752, sensitivity: 0.600, and specificity: 0.835) and I stage breast cancer (AUC: 0.755, sensitivity: 0.733, and specificity: 0.742) in the validation cohort. The diagnostic model of I stage breast cancer exhibited a high accuracy of 0.902 in double-blind cohort.

CONCLUSIONS

This study could contribute to the screening for patients with early-stage breast cancer based on precise alterations of salivary glycopatterns.

Characterization of proteins with Siaα2-3/6Gal-linked glycans from bovine milk and role of their glycans against influenza A virus

The bovine milk proteins have a wide range of functions, but the role of the attached glycans in their biological functions has not been fully understood yet.

N-glycan profiles in H9N2 avian influenza viruses from chicken eggs and human embryonic lung fibroblast cells

N-glycosylation can affect the host specificity, virulence and infectivity of influenza A viruses (IAVs). In this study, the distribution and evolution of N-glycosylation sites in the hemagglutinin (HA) and neuraminidase (NA) of H9N2 virus were explored using phylogenetic analysis. Then, one strain of the H9N2 subtypes was proliferated in the embryonated chicken eggs (ECE) and human embryonic lung fibroblast cells (MRC-5) system. The proliferated viral N-glycan profiles were analyzed by a glycomic method that combined the lectin microarray and MALDI-TOF/TOF-MS. As a result, HA and NA of H9N2 viruses prossess six and five highly conserved N-glycosylation sites, respectively. Sixteen lectins (e.g., MAL-II, SNA and UEA-I) had increased expression levels of the glycan structures in the MRC-5 compared with the ECE system; however, 6 lectins (e.g., PHA-E, PSA and DSA) had contrasting results. Eleven glycans from the ECE system and 13 glycans from the MRC-5 system were identified. Our results showed that the Fucα-1,6GlcNAc(core fucose) structure was increased, and pentaantennary N-glycans were only observed in the ECE system. The SAα2-3/6Gal structures were highly expressed and Fucα1-2Galβ1-4GlcNAc structures were only observed in the MRC-5 system. We conclude that the existing SAα2-3/6Gal sialoglycans make the offspring of the H9N2 virus prefer entially attach to each other, which decreases the virulence. Alterations in the glycosylation sites for the evolution and role of IAVs have been widely described; however, little is known about the exact glycan structures for the same influenza strain from different hosts. Our findings may provide a novel way for further discussing the molecular mechanism of the viral transmission and virulence associated with viral glycosylation in avian and human hosts as well as vital information for designing a vaccine against influenza and other human viruses.

Serum glycopattern and Maackia amurensis lectin-II binding glycoproteins in autism spectrum disorder

The pathophysiology of autistic spectrum disorder (ASD) is not fully understood and there are no diagnostic or predictive biomarkers. Glycosylation modified as many as 70% of all human proteins can sensitively reflect various pathological changes. However, little is known about the alterations of glycosylation and glycoproteins in ASD. In this study, serum glycopattern and the maackia amurensis lectin-II binding glycoproteins (MBGs) in 65 children with ASD and 65 age-matched typically developing (TD) children were compared by using lectin microarrays and lectin-magnetic particle conjugate-assisted LC-MS/MS analyses. Expression of Siaα2-3 Gal/GalNAc was significantly increased in pooled (fold change = 3.33, p < 0.001) and individual (p = 0.009) serum samples from ASD versus TD children. A total of 194 and 217 MGBs were identified from TD and ASD sera respectively, of which 74 proteins were specially identified or up-regulated in ASD. Bioinformatic analysis revealed abnormal complement cascade and aberrant regulation of response-to-stimulus that might be novel makers or markers for ASD. Moreover, increase of APOD α2-3 sialoglycosylation could sensitively and specifically distinguish ASD samples from TD samples (AUC is 0.88). In conclusion, alteration of MBGs expression and their sialoglycosylation may serve as potential biomarkers for diagnosis of ASD, and provide useful information for investigations into the pathogenesis of ASD.

Roles of Glycoproteins in the Diagnosis and Differential Diagnosis of Chronic and Latent Keshan Disease

We aimed to explore the roles of glycoproteins in the pathogenesis of chronic and latent Keshan disease (CKD and LKD), and screen the lectins as indicators of significant differences in glycoproteins of KD saliva and serum. Blood and saliva were collected from 50 CKD, 50 LKD patients and 54 normal individuals. Saliva and serum lectin microarrays and saliva and serum microarrays were used to screen and verify the differences in the levels of lectin among the three groups. In the male saliva lectin microarray, Solanum tuberosum (potato) lectin (STL) and other 9 lectins showed differences between CKD and normal; STL and other 9 lectins showed differences between LKD and normal; Aleuria aurantia lectin (AAL) and other 15 lectins showed differences between CKD and LKD. In the female saliva microarray, Griffonia (Bandeiraea) simplicifolia lectin I (GSL-I) and other 9 lectins showed differences between CKD and normal; STL and other 7 lectins showed differences between LKD and normal; Maackia amurensis lectin I (MAL-I) and Triticum vulgaris (WGA) showed difference between CKD and LKD. In the male serum lectin microarray, Psophocarpus tetragonolobus lectin I (PTL-I) and other 16 lectins showed differences between CKD and normal; Ulexeuropaeus agglutinin I (UEA-I) and other 9 lectins showed differences between LKD and normal; AAL and other 13 lectins showed differences between CKD and LKD. In the female serum lectin microarray, WGA and other 13 lectins showed differences between CKD and normal; Euonymus europaeus lectin (EEL) and other 6 lectins showed differences between LKD and normal; MAL-I and other 14 lectins showed differences between CKD and LKD. Carbohydrate chain GlcNAc and α-Gal may play crucial roles in the pathogenesis of KD. STL may be considered the diagnostic biomarker for male CKD and LKD, while WGA may be useful in distinguishing between the two stages. STL may be considered the diagnostic biomarker for female LKD.

A pilot study of salivary N-glycome in HBV-induced chronic hepatitis, cirrhosis, and hepatocellular carcinoma

Hepatitis B is a potentially life-threatening liver infection caused by the hepatitis B virus (HBV), which can lead to chronic liver disease and put people at high risk of death from cirrhosis of the liver and liver cancer. However, little is known about the correlation of salivary N-linked glycans related to HBV-infected liver diseases. Here we investigated N-linked glycome in saliva from 200 subjects (50 healthy volunteers (HV), 40 HBV-infected patients (HB), 50 cirrhosis patients (HC), and 60 hepatocellular carcinoma patients (HCC) using MALDI-TOF/TOF-MS. Representative MS spectra of N-glycans with signal-to-noise ratios >6 were annotated using the GlycoWorkbench program. A total of 40, 47, 29, and 33 N-glycan peaks were identified and annotated from HV, HB, HC, and HCC groups, respectively. There were 15 N-glycan peaks (e.g., m/z 1647.587, 1688.613 and 2101.755) were present in all groups. Three N-glycan peaks (m/z 2596.925, 2756.962, and 2921.031) were unique in HV group, 2 N-glycan peaks (m/z 1898.676 and 1971.692) were unique in HB group, 5 N-glycan peaks (m/z 1954.677, 2507.914, 2580.930, 2637.952, and 3092.120) were unique in HC group, and 3 N-glycan peaks (m/z 2240.830, 2507.914, and 3931.338) were unique in HCC group. The proportion of fucosylated N-glycans was apparently increased in the HCC group (84.8%) than in any other group (73.1% ± 0.01), however, the proportion of sialylated N-glycans was decreased in HCC group (12.1%) than in any other group (17.23% ± 0.003). Our data provide pivotal information to distinguish between HBV-associated hepatitis, cirrhosis and HCC, and facilitate the discovery of biomarkers for HCC during its early stages based on precise alterations of N-linked glycans in saliva.

Serum Glycopatterns as Novel Potential Biomarkers for Diagnosis of Acute-on-Chronic Hepatitis B Liver Failure

Acute-on-chronic hepatitis B liver failure (ACHBLF) is an increasingly recognized distinct disease entity encompassing an acute deterioration of liver function in patients with cirrhosis, so little is known about the alterations of protein glycopatterns in serum with its development. We aimed to identify the alterations of serum glycopatterns in ACHBLF and probe the possibility of them as novel potential biomarkers for diagnosis of ACHBLF. As a result, there were 18 lectins (e.g., WFA, GSL-II, and PNA) to give significantly alterations of serum glycopatterns in ACHBLF compared with healthy controls (HC) (all p ≤ 0.0386). Meanwhile, among these lectins, there were 12 lectins (e.g., WFA, GAL-II, and EEL) also exhibited significantly alterations of serum glycopatterns in ACHBLF compared with HBV-infected chronic hepatitis (cHB) (all p ≤ 0.0252). The receiver-operating characteristic (ROC) curve analysis indicated there were 5 lectins (PHA-E + L, BS-I, ECA, ACA, and BPL) had the greatest discriminatory power for distinguishing ACHBLF and HC or cHB, respectively (all p ≤ 0.00136). We provided a new basic insight into serum glycopatterns in ACHBLF and investigated the correlation of alterations in serum glycopatterns as novel potential biomarkers for diagnosis of ACHBLF.

Comparison of the glycopattern alterations of mitochondrial proteins in cerebral cortex between rat Alzheimer's disease and the cerebral ischemia model

Alzheimer’s disease (AD) and ischemic brain injury are two major neurodegenerative diseases. Mitochondrial dysfunction commonly occurs in AD and ischemic brain injury. Currently, little attention has been paid to the glycans on mitochondrial glycoproteins, which may play vital roles during the process of mitochondrial dysfunction. The aim of this study was to illustrate and compare the glycopattern alterations of mitochondrial glycoproteins extracted from the cerebral cortex of the rat models of these two diseases using High-throughput lectin microarrays. The results shown that the number of lectins with significant differences compared to normal brains was nine for the rat sporadic Alzheimer’s disease (SAD) model and eighteen for the rat middle cerebral artery occlusion (MCAO) model. Interestingly, five lectins showed opposite expression patterns between the SAD and MCAO rat models. We conclude that glycopattern alterations of mitochondrial glycoproteins in the cerebral cortex may provide vital information to help understand mitochondrial dysfunction in AD and ischemic brain injury. In addition, glycans recognized by diverse lectins with opposite expression patterns between these two diseases hints at the different pathomechanisms of mitochondrial dysfunction in AD and ischemic brain injury.

Identification and localization of xylose-binding proteins as potential biomarkers for liver fibrosis/cirrhosis

In our recent study, we found that the expression levels of total xylose-binding proteins (XBPs) were up-regulated significantly in activated hepatic stellate cells (HSCs); however, the denomination, distribution, and function of the XBPs were uncharted. Herein, 70 XBPs from activated HSCs and 64 XBPs from quiescent HSCs were isolated, identified and annotated. A total of 30 XBPs were up-regulated (all fold change ≥ 1.5, p ≤ 0.05) and 14 XBPs were down-regulated (all fold change ≤ 0.67, p ≤ 0.05) in the activated HSCs. The XBPs were localized at the cytoplasm and cytoplasmic membrane in HSCs and cirrhotic liver tissues by cy/histochemistry. The XBPs (i.e. PDIA6 and CFL2) responsible for the regulation of protein binding were up-regulated and those responsible for the regulation of catalytic activity (i.e. TUBB and MX1) were up-regulated in the activated HSCs. 2 candidates (i.e. PDIA6 and APOA1) were then selected for further verification in the sera of patients with HBV-induced chronic hepatitis/cirrhosis using western blotting and serum microarrays. PDIA6 showed a higher discrimination (Area Under Curves, AUCs = 0.8985, p < 0.0001) relative to APOA1 (AUCs = 0.8738, p < 0.0001) in the sera of patients as biomarker candidate. In conclusion, the precision alteration of the XBPs associated with pathological changes in HSCs during liver fibrosis/cirrhosis may provide pivotal information needed to discover potential glycan-binding protein-related biomarkers for diagnosis of liver fibrosis/cirrhosis and for development of new anti-fibrotic strategies.

Alteration of liver glycopatterns during cirrhosis and tumor progression induced by HBV

The incidence of hepatocellular carcinoma (HCC) is closely correlated with hepatitis B virus (HBV)-induced liver cirrhosis. Structural changes in the glycans of serum and tissue proteins are reliable indicators of liver damage. However, little is known about the alteration of liver glycopatterns during cirrhosis and tumor progression induced by HBV infection. This study compared the differential expression of liver glycopatterns in 7 sets of normal pericarcinomatous tissues (PCTs), cirrhotic, and tumor tissues from patients with liver cirrhosis and HCC induced by HBV using lectin microarrays. Fluorescence-based lectin histochemistry and lectin blotting were further utilized to validate and assess the expression and distribution of certain glycans in 9 sets of corresponding liver tissue sections. Eight lectins (e.g., Jacalin and AAL) revealed significant difference in cirrhotic tissues versus PCTs. Eleven lectins (e.g., EEL and SJA) showed significant alteration during cirrhotic and tumor progression. The expression of Galα1-3(Fucα1-2)Gal (EEL) and fucosyltransferase 1 was mainly increasing in the cytoplasm of hepatocytes during PCTs-cirrhotic-tumor tissues progression, while the expression of T antigen (ACA and PNA) was decreased sharply in cytoplasm of tumor hepatocytes. Understanding the precision alteration of liver glycopatterns related to the development of hepatitis, cirrhosis, and tumor induced by HBV infection may help elucidate the molecular mechanisms underlying the progression of chronic liver diseases and develop new antineoplastic therapeutic strategies.

Characterization and sub-cellular localization of GalNAc-binding proteins isolated from human hepatic stellate cells

Although the expression levels of total GalNAc-binding proteins (GNBPs) were up-regulated significantly in human hepatic stellate cells (HSCs) activated with transforming growth factor-β1(TGF-β1), yet little is known about the precise types, distribution and sub-cellular localization of the GNBPs in HSCs. Here, 264 GNBPs from the activated HSCs and 257 GNBPs from the quiescent HSCs were identified and annotated. A total of 46 GNBPs were estimated to be significantly up-regulated and 40 GNBPs were estimated to be significantly down-regulated in the activated HSCs. For example, the GNBPs (i.e. BTF3, COX17, and ATP5A1) responsible for the regulation of protein binding were up-regulated, and those (i.e. FAM114A1, ENO3, and TKT) responsible for the regulation of protein binding were down-regulated in the activated HSCs. The motifs of the isolated GNBPs showed that Proline residue had the maximum preference in consensus sequences. The western blotting showed the expression levels of COX17, and PRMT1 were significantly up-regulated, while, the expression level of CLIC1(B5) was down-regulated in the activated HSCs and liver cirrhosis tissues. Moreover, the GNBPs were sub-localized in the Golgi apparatus of HSCs. In conclusion, the precision alteration of the GNBPs referred to pathological changes in liver fibrosis/cirrhosis may provide useful information to find new molecular mechanism of HSC activation and discover the biomarkers for diagnosis of liver fibrosis/cirrhosis as well as development of new anti-fibrotic strategies.

Altered glycomics in liver disease

Chronic liver diseases are a serious health problem worldwide. The biosynthesis of proteins takes place in the liver, and protein glycosylation is the most common form of post-translational modification of proteins, with as many as 70% of all human proteins estimated to contain one or more glycan chains. Protein glycosylation is the enzymatic addition of sugars or oligosaccharides to proteins, which increases the diversity of the proteome to a level unmatched by any other post-translational modifications because of the various aspects of modification, including glycosidic bond, glycan composition, glycan structure, and glycan length. Changes in the glycan structures of proteins are an indication for liver damage, which plays an important role in the pathogenesis and progression of various liver diseases. The aim of this paper is to give an overview of the altered protein glycosylation in different etiologies of hepatitis, liver fibrosis/cirrhosis, hepatocellular carcinoma, alcoholic and fatty liver diseases based on the analysis of serum and saliva using the glycomics technology.