N- glycolylneuraminic acid (Neu5Gc) is a type of sialic acid, it can be synthesized by a range of mammals except chickens and healthy human. After entering human body, Neu5Gc in foods such as red ...meat and milk can cause chronic inflammation, thus promoting the development of cancer and related diseases. In this study, we identified a gene sequence of Neu5Gc-specific single-chain variable fragment (ScFv) by phage display from a primary chicken antibodies library. Then the gene sequence was used to express a 29 kDa anti-Neu5Gc ScFv protein as detection probe in competitive inhibition ELISA (IC-ELISA). The linear regression equation of the IC-ELISA was y = 23.12x+33.19 (R = 0.980), and the half-maximal inhibitory concentration (IC50) and the limit of detection (LOD) was 5.333 and 0.66 μg/mL. The mean recovery of the spiked samples was 83.04%, and the intra-assay and inter-assay coefficients of variation (CVs) were both 5.59%. The results suggested that the specific anti-Neu5Gc ScFv is a promising probe for the development of IC-ELISA and test strip in order to detect the presence of Neu5Gc in red meat, milk, and tumor tissues.
•Several 29 kDa ScFv against Neu5Gc were retrieved from phage ScFv library from chicken immunized with Neu5Gc-KLH.•The IC-ELISA based on ScFv was developed with IC50 of 5.333 μg/mL and LOD of 0.66 μg/mL.•Spiked food samples were detected by IC-ELISA with the mean recovery of 83.04% and CV of 5.59%.
Background
Antibody‐mediated rejection has long been known to be one of the major organ failure mechanisms in xenotransplantation. In addition to the porcine α1,3‐galactose (α1,3Gal) epitope, ...N‐Glycolylneuraminic acid (Neu5Gc), a sialic acid, has been identified as an important porcine antigen against which most humans have pre‐formed antibodies. Here we evaluate GalTKO.hCD46 lungs with an additional cytidine monophospho‐N‐acetylneuraminic acid hydroxylase (CMAH) gene knock‐out (Neu5GcKO) in a xenogeneic ex vivo perfusion model
Methods
Eleven GalTKO.hCD46.Neu5GcKO pig lungs were perfused for up to 6 h with fresh heparinized human blood. Six of them were treated with histamine (H) blocker famotidine and 1‐thromboxane synthase inhibitor Benzylimidazole (BIA) and five were left untreated. GalTKO.hCD46 lungs without Neu5GcKO (n = 18: eight untreated and 10 BIA+H treated) served as a reference. Functional parameters, blood, and tissue samples were collected at pre‐defined time points throughout the perfusion
Results
All but one Neu5GcKO organs maintained adequate blood oxygenation and “survived” until elective termination at 6 h whereas two reference lungs failed before elective termination at 4 h. Human anti‐Neu5Gc antibody serum levels decreased during the perfusion of GalTKO.hCD46 lungs by flow cytometry (∼40% IgM, 60% IgG), whereas antibody levels in Neu5GcKO lung perfusions did not fall (IgM p = .007; IgG p < .001). Thromboxane elaboration, thrombin generation, and histamine levels were significantly reduced with Neu5GcKO lungs compared to reference in the untreated groups (p = .007, .005, and .037, respectively); treatment with BIA+H masked these changes. Activation of platelets, measured as CD62P expression on circulating platelets, was lower in Neu5GcKO experiments compared to reference lungs (p = .023), whereas complement activation (as C3a rise in plasma) was not altered. MCP‐1 and lactotransferin level elevations were blunted in Neu5GcKO lung perfusions (p = .007 and .032, respectively). Pulmonary vascular resistance (PVR) rise was significantly attenuated and delayed in untreated GalTKO.hCD46.Neu5GcKO lungs in comparison to the untreated GalTKO.hCD46 lungs (p = .003)
Conclusion
Additional Neu5GcKO in GalTKO.hCD46 lungs significantly reduces parameters associated with antibody‐mediated inflammation and activation of the coagulation cascade. Knock‐out of the Neu5Gc sialic acid should be beneficial to reduce innate immune antigenicity of porcine lungs in future human recipients.
Animal glycan-recognizing proteins can be broadly classified into two groups--lectins (which typically contain an evolutionarily conserved carbohydrate-recognition domain CRD) and sulfated ...glycosaminoglycan (SGAG)-binding proteins (which appear to have evolved by convergent evolution). Proteins other than antibodies and T-cell receptors that mediate glycan recognition via immunoglobulin (Ig)-like domains are called "I-type lectins." The major homologous subfamily of I-type lectins with sialic acid (Sia)-binding properties and characteristic amino-terminal structural features are called the "Siglecs" (Sia-recognizing Ig-superfamily lectins). The Siglecs can be divided into two groups: an evolutionarily conserved subgroup (Siglecs-1, -2, and -4) and a CD33/Siglec-3-related subgroup (Siglecs-3 and -5-13 in primates), which appear to be rapidly evolving. This article provides an overview of historical and current information about the Siglecs.
Abstract The etiology of multiple sclerosis (MS) remains elusive. Among the possible causes, the increase of anti-Neu5Gc antibodies during EBV primo-infection of Infectious mononucleosis (IMN) may ...damage the integrity of the blood-brain barrier facilitating the transfer of EBV-infected B cells and anti-EBV T cell clones in the brain. We investigated the change in titers of anti-Neu5Gc and anti-α1,3 Galactose antibodies in 49 IMN, in 76 MS, and 73 clinically isolated syndrome (CIS) patients, as well as age/gender-matched healthy individuals. Anti-Gal and anti-Neu5Gc are significantly increased during IMN (p = 0.02 and p < 1.10 − 4 respectively), but not in acute CMV primo-infection. We show that, whereas there was no change in anti-Neu5Gc in MS/CIS, the two populations exhibit a significant decrease in anti-Gal (combined p = 2.7.10 − 3 ), in contrast with patients with non-MS/CIS central nervous system pathologies. Since anti-Gal result from an immunization against α1,3 Gal, lacking in humans but produced in the gut, our data suggest that CIS and MS patients have an altered microbiota or an altered response to this microbiotic epitope.
Two well‐characterized carbohydrate epitopes are absent in humans but present in other mammals. These are galactose‐α1,3‐galactose (αGal) and N‐glycolylneuraminic acid (Neu5Gc) which are introduced ...by the activities of two enzymes including α(1,3) galactosyltransferase (encoded by the GGTA1 gene) and CMP‐Neu5Gc hydroxylase (encoded by the CMAH gene) that are inactive in humans but present in cattle. Hence, bovine‐derived products are antigenic in humans who receive bioprosthetic heart valves (BHVs) or those that suffer from red meat syndrome. Using programmable nucleases, we disrupted (knockout, KO) GGTA1 and CMAH genes encoding for the enzymes that catalyse the synthesis of αGal and Neu5Gc, respectively, in both male and female bovine fibroblasts. The KO in clonally selected fibroblasts was detected by polymerase chain reaction (PCR) and confirmed by Sanger sequencing. Selected fibroblasts colonies were used for somatic cell nuclear transfer (SCNT) to produce cloned embryos that were implanted in surrogate recipient heifers. Fifty‐three embryos were implanted in 33 recipients heifers; 3 pregnancies were carried to term and delivered 3 live calves. Primary cell cultures were established from the 3 calves and following molecular analyses confirmed the genetic deletions. FACS analysis showed the double‐KO phenotype for both antigens confirming the mutated genotypes. Availability of such cattle double‐KO model lacking both αGal and Neu5Gc offers a unique opportunity to study the functionality of BHV manufactured with tissues of potentially lower immunogenicity, as well as a possible new clinical approaches to help patients with red meat allergy syndrome due to the presence of these xenoantigens in the diet.
Abstract
The mucin-type O-glycome in cancer aberrantly expresses the truncated glycans Tn (GalNAcα1-Ser/Thr) and STn (Neu5Acα2,6GalNAcα1-Ser/Thr). However, the role of Tn and STn in cancer and other ...diseases is not well understood. Our recent discovery of the self-binding properties (carbohydrate–carbohydrate interactions, CCIs) of Tn (Tn–Tn) and STn (STn–STn) provides a model for their possible roles in cellular transformation. We also review evidence that Tn and STn are members of a larger family of glycan tumor antigens that possess CCIs, which may participate in oncogenesis.
A positive correlation between massive red meat consumption with colorectal cancer had been reported. Given the complexity of meat components, we focused on investigating the role of Neu5Gc in human ...healthy. Two groups, either feeding with normal and overdose concentration of Neu5Gc for two weeks, to mimic the normal and overconsumption of red meat conditions in human, respectively. The colorectal transcriptomes revealed that Neu5Gc promotes intestinal immune response and identified the hub genes positively correlated with colorectal cancer such as Tnf, Cd19, Muc13, and Nso2,. The colorectal cancer patients have a 25–30% chance of developing liver metastases, thus we sequenced the liver and revealed the role of Neu5Gc in regulating cell metabolism. Moreover, we found that Neu5Gc negatively regulates the expression of Cmah. We conclude that high Neu5Gc intake promotes colorectal inflammatory responses in ApcMin/+ mice, and suppresses colorectal and hepatic metabolic and digestive processes through Cmah inhibition.
Sialic acids, a group of acidic sugars abundantly expressed in the tissues of deuterostome animals but rarely found in microbes, serve as a "signature of self" for these animals. Cognate sensors for ...sialic acids include Siglecs, a family of transmembrane lectins of vertebrate immune systems that recognize glycans containing sialic acids. A type of sialic acid called
-glycolylneuraminic acid (Neu5Gc) is abundant in many mammalian lineages including great apes, the closest extant relatives of modern human, but was lost in the lineage leading to modern human via the pseudogenization of the
gene encoding the enzyme that converts
-acetylneuraminic acid (Neu5Ac) to Neu5Gc. Loss of Neu5Gc appears to have influenced the evolution of human Siglecs, such as the adjustment of sialic acid binding preferences and the inactivation of at least one Siglec. In addition, various mechanistic studies using model systems and genetic association studies have revealed that some human Siglecs interact with pathogens and influence the outcome of infections, and these pathogens in turn likely influence the evolution of these Siglecs. By understanding the evolutionary forces affecting Siglecs, we shall achieve a better appreciation of Siglec functions, and by understanding Siglec functions, we can obtain deeper insight into the evolutionary processes driving Siglec evolution.
The hazardous substance Neu5Gc (N-glycolylneuraminic acid), which is rich in red meat, is related to chronic inflammation but is hard to eliminate. Here, electrical stimulation, as a food-friendly ...nonthermal processing technology, was applied to red meat samples to reduce the Neu5Gc content. To explore the Neu5Gc structure changes during this process, electronic structure parameters were evaluated, and AIM (atom in molecules) theory and DFT (density function theory) calculations were further used. The results showed that the content of Nue5Gc in red meat can be reduced by (74.24 ± 0.69)% at 120V for 50s, with little impact on the meat texture and color. Theoretical calculations indicated that the Neu5Gc molecule becomes very unstable under electrical stimulation by increasing the OH bond length, reactive activity, strength of intermolecular dipole forces and total energy through reducing the values of bond dissociation energy and strength of intramolecular hydrogen bonds. Overall, this research provides an economical method to effectively control red meat safety.
PDF
