Montoya AL, Austin VM, Portillo S, Vinales I, Ashmus RA, et al.
JACS Au ā¢
All healthy humans have high levels of natural anti-Ī±-galactosyl (Ī±-Gal) antibodies (elicited by yet uncharacterized glycotopes), which may play important roles in immunoglycomics: (a) potential protection against certain parasitic and viral zoonotic infections; (b) targeting of Ī±-Gal-engineered cancer cells; (c) aiding in tissue repair; and (d) serving as adjuvants in Ī±-Gal-based vaccines. Patients with certain protozoan infections have specific anti-Ī±-Gal antibodies, elicited against parasite-derived Ī±-Gal-bearing glycotopes. These glycotopes, however, remain elusive except for the well-characterized glycotope GalĪ±1,3GalĪ²1,4GlcNAcĪ±, expressed by . The discovery of new parasitic glycotopes is greatly hindered by the enormous structural diversity of cell-surface glycans and the technical challenges of classical immunoglycomics, a top-down approach from cultivated parasites to isolated glycans. Here, we demonstrate that reversed immunoglycomics, a bottom-up approach, can identify parasite species-specific Ī±-Gal-bearing glycotopes by probing synthetic oligosaccharides on neoglycoproteins. This method was tested here seeking to identify as-yet unknown glycotopes specific for , the causative agent of Old-World cutaneous leishmaniasis (OWCL). Neoglycoproteins decorated with synthetic Ī±-Gal-containing oligosaccharides derived from glycoinositolphospholipids served as antigens in a chemiluminescent enzyme-linked immunosorbent assay using sera from OWCL patients and noninfected individuals. Receiver-operating characteristic analysis identified GalĪ±1,3GalĪ² and GalĪ±1,3GalĪ²1,3ManĪ± glycotopes as diagnostic biomarkers for caused OWCL, which can distinguish with 100% specificity from heterologous diseases and caused OWCL. These glycotopes could prove useful in the development of rapid Ī±-Gal-based diagnostics and vaccines for OWCL. Furthermore, this method could help unravel cryptic Ī±-Gal-glycotopes of other protozoan parasites and enterobacteria that elicit the natural human anti-Ī±-Gal antibodies.
Subramaniam KS, Austin V, Schocker NS, Montoya AL, Anderson MS, et al.
Parasitology ā¢
Outbreaks of Old World cutaneous leishmaniasis (CL) have significantly increased due to the conflicts in the Middle East, with most of the cases occurring in resource-limited areas such as refugee settlements. The standard methods of diagnosis include microscopy and parasite culture, which have several limitations. To address the growing need for a CL diagnostic that can be field applicable, we have identified five candidate neoglycoproteins (NGPs): GalĪ± (NGP3B), GalĪ±(1,3)GalĪ± (NGP17B), GalĪ±(1,3)GalĪ² (NGP9B), GalĪ±(1,6)[GalĪ±(1,2)]GalĪ² (NGP11B), and GalĪ±(1,3)GalĪ²(1,4)GlcĪ² (NGP1B) that are differentially recognized in sera from individuals with Leishmania major infection as compared with sera from heterologous controls. These candidates contain terminal, non-reducing Ī±-galactopyranosyl (Ī±-Gal) residues, which are known potent immunogens to humans. Logistic regression models found that NGP3B retained the best diagnostic potential (area under the curve from receiver-operating characteristic curve = 0.8). Our data add to the growing body of work demonstrating the exploitability of the human anti-Ī±-Gal response in CL diagnosis.
In the Kingdom of Saudi Arabia (KSA), Old World cutaneous leishmaniasis (CL) is mainly caused by Leishmania major and Leishmania tropica parasites. Diagnosis of CL is predominately made by clinicians, who at times fail to detect the disease and are unable to identify parasite species. Here, we report the development of a chemiluminescent enzyme-linked immunosorbent assay (CL-ELISA) to measure the levels of anti-Ī±-galactosyl antibodies in human sera. Using this assay, we have found that individuals infected with either Leishmania spp. had significantly elevated levels (up to 9-fold higher) of anti-Ī±-Gal IgG compared to healthy control individuals. The assay sensitivity was 96% for L. major (95% CI; 94-98%) and 91% for L. tropica (95% CI; 86-98%) infections and therefore equivalent to restriction fragment length polymorphism-polymerase chain reaction analysis of parasite ITS1 gene. In addition, the assay had higher sensitivity than microscopy analysis, which only detected 68 and 45% of the L. major and L. tropica infections, respectively. Interestingly, up to 2 years following confirmed CL cure individuals had 28-fold higher levels of anti-Ī±-Gal IgG compared to healthy volunteers. Monitoring levels of anti-Ī±-Gal antibodies can be exploited as both a diagnostic tool and as a biomarker of cure of Old World CL in disease elimination settings.
Commins SP, Kelly LA, Rƶnmark E, James HR, Pochan SL, et al.
American journal of respiratory and critical care medicine ā¢
IgE antibodies to the mammalian oligosaccharide galactose-Ī±-1,3-galactose (Ī±-gal) are common in the southeastern United States. These antibodies, which are induced by ectoparasitic ticks, can give rise to positive skin tests or serum assays with cat extract. To evaluate the relationship between IgE antibodies to Ī±-gal and asthma, and compare this with the relationship between asthma and IgE antibodies to Fel d 1 and other protein allergens. Patients being investigated for recurrent anaphylaxis, angioedema, or acute urticaria underwent spirometry, exhaled nitric oxide, questionnaires, and serum IgE antibody assays. The results were compared with control subjects and cohorts from the emergency department in Virginia (n = 130), northern Sweden (n = 963), and rural Kenya (n = 131). Patients in Virginia with high-titer IgE antibodies to Ī±-gal had normal lung function, low levels of exhaled nitric oxide, and low prevalence of asthma symptoms. Among patients in the emergency department and children in Kenya, there was no association between IgE antibodies to Ī±-gal and asthma (odds ratios, 1.04 and 0.75, respectively). In Sweden, IgE antibodies to cat were closely correlated with IgE antibodies to Fel d 1 (r = 0.83) and to asthma (P < 0.001). These results provide a model of an ectoparasite-induced specific IgE response that can increase total serum IgE without creating a risk for asthma, and further evidence that the main allergens that are causally related to asthma are those that are inhaled.
Commins SP, James HR, Kelly LA, Pochan SL, Workman LJ, et al.
The Journal of allergy and clinical immunology ā¢
In 2009, we reported a novel form of delayed anaphylaxis to red meat that is related to serum IgE antibodies to the oligosaccharide galactose-Ī±-1,3-galactose (alpha-gal). Most of these patients had tolerated meat for many years previously. The implication is that some exposure in adult life had stimulated the production of these IgE antibodies. We sought to investigate possible causes of this IgE antibody response, focusing on evidence related to tick bites, which are common in the region where these reactions occur. Serum assays were carried out with biotinylated proteins and extracts bound to a streptavidin ImmunoCAP. Prospective studies on IgE antibodies in 3 subjects after tick bites showed an increase in levels of IgE to alpha-gal of 20-fold or greater. Other evidence included (1) a strong correlation between histories of tick bites and levels of IgE to alpha-gal (Ļ(2)Ā = 26.8, PĀ < .001), (2) evidence that these IgE antibodies are common in areas where the tick Amblyomma americanum is common, and (3) a significant correlation between IgE antibodies to alpha-gal and IgE antibodies to proteins derived from A americanum (r(s)Ā = 0.75, PĀ < .001). The results presented here provide evidence that tick bites are a cause, possibly the only cause, of IgE specific for alpha-gal in this area of the United States. Both the number of subjects becoming sensitized and the titer of IgE antibodies to alpha-gal are striking. Here we report the first example of a response to an ectoparasite giving rise to an important form of food allergy.