Possible molecular basis for macromolecular antigen attachment to host cells: their immune complex with plasma antibodies have unoccupied binding sites enabling binding to smaller ligands

Genu George; Sumita K. Chellappan; Mandagini Geetha; Padinjaradath S. Appukuttan; Genu George; Sumita K. Chellappan; Mandagini Geetha; Padinjaradath S. Appukuttan

doi:10.3934/molsci.2017.1.91

AIMS Molecular Science

2017, Volume 4, Issue 1: 91-102. doi: 10.3934/molsci.2017.1.91

Previous Article Next Article

Research article Topical Sections

Possible molecular basis for macromolecular antigen attachment to host cells: their immune complex with plasma antibodies have unoccupied binding sites enabling binding to smaller ligands

Department of Biochemistry, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram-695 011, India

Received: 11 December 2016 Accepted: 24 February 2017 Published: 01 March 2017

Macromolecules such as lipoprotein(a) and antigens of Streptococcus mutans that cause dental infections accumulate in perivascular cells in inflammatory vascular disorders though they do not bind host cells directly. Suspecting a role for cognate circulating antibodies in the molecular mechanisms of macromolecular antigen deposition in tissues we investigated the ligand binding properties of de novo immune complexes (IC) formed between these two entities. Negatively charged Streptococcus mutans antigens (NSMAg) from cultured bacteria and apo(a) subunit separated from human plasma lipoprotein (a) were used as antigens to interact with anti β-glucan (ABG) and anti-α-galactoside (anti-Gal) antibodies respectively of normal plasma. Binding of antigen to antibody was measured in terms of the enhancement of fluorescence of FITC-labeled antibody that accompanies antigen binding. Unoccupied binding sites on macromolecular antigen-antibody ICs were demonstrated by capturing them on smaller ligands immobilized on microplates. Biotin-labeled macromolecular antigens were detected in ICs using HRP-labeled avidin. While total Streptococcus mutans antigens and a synthetic glycoprotein in which an ABG-specific disaccharide (cellobiose) had been covalently attached were equal in avidity towards ABG, NSMAg was superior. When binding of antibody to plate-coated ligands was monitored using HRP-labeled anti-immunoglobulin preincubation of ABG or anti-Gal with respective macromolecular antigens significantly enhanced binding response whereas antibodies preincubated with small sugars were fully inhibited from binding, indicating that macromolecular antigen binding had activated the Fc part of antibodies and that the resulting ICs in turn bound to other ligands using binding sites in the antibody spared by the large antigens. Presence of biotinylated macromolecular antigen in IC bound to immobilized ligands was confirmed using avidin-HRP probe. Unoccupied binding sites in the antibodies involved may enable homing of macromolecule ICs on vascular cells possessing smaller ligands. This along with an activated Fc could enhance their inflammatory potential.
- immune complex,
- anti-β-glucan antibody,
- anti-α-galactoside antibody,
- Streptococcus mutans
Citation: Genu George, Sumita K. Chellappan, Mandagini Geetha, Padinjaradath S. Appukuttan. Possible molecular basis for macromolecular antigen attachment to host cells: their immune complex with plasma antibodies have unoccupied binding sites enabling binding to smaller ligands[J]. AIMS Molecular Science, 2017, 4(1): 91-102. doi: 10.3934/molsci.2017.1.91

Related Papers:

Abstract

Macromolecules such as lipoprotein(a) and antigens of Streptococcus mutans that cause dental infections accumulate in perivascular cells in inflammatory vascular disorders though they do not bind host cells directly. Suspecting a role for cognate circulating antibodies in the molecular mechanisms of macromolecular antigen deposition in tissues we investigated the ligand binding properties of de novo immune complexes (IC) formed between these two entities. Negatively charged Streptococcus mutans antigens (NSMAg) from cultured bacteria and apo(a) subunit separated from human plasma lipoprotein (a) were used as antigens to interact with anti β-glucan (ABG) and anti-α-galactoside (anti-Gal) antibodies respectively of normal plasma. Binding of antigen to antibody was measured in terms of the enhancement of fluorescence of FITC-labeled antibody that accompanies antigen binding. Unoccupied binding sites on macromolecular antigen-antibody ICs were demonstrated by capturing them on smaller ligands immobilized on microplates. Biotin-labeled macromolecular antigens were detected in ICs using HRP-labeled avidin. While total Streptococcus mutans antigens and a synthetic glycoprotein in which an ABG-specific disaccharide (cellobiose) had been covalently attached were equal in avidity towards ABG, NSMAg was superior. When binding of antibody to plate-coated ligands was monitored using HRP-labeled anti-immunoglobulin preincubation of ABG or anti-Gal with respective macromolecular antigens significantly enhanced binding response whereas antibodies preincubated with small sugars were fully inhibited from binding, indicating that macromolecular antigen binding had activated the Fc part of antibodies and that the resulting ICs in turn bound to other ligands using binding sites in the antibody spared by the large antigens. Presence of biotinylated macromolecular antigen in IC bound to immobilized ligands was confirmed using avidin-HRP probe. Unoccupied binding sites in the antibodies involved may enable homing of macromolecule ICs on vascular cells possessing smaller ligands. This along with an activated Fc could enhance their inflammatory potential.

References

[1]	Roivainen M, Viik-Kajander M, Palosuo T, et al. (2000) Infections, inflammation, and the risk of coronary heart disease. Circulation 101: 252-257. doi: 10.1161/01.CIR.101.3.252
[2]	Denes A, Humphreys N, Lane TE, et al. (2010) Chronic Systemic Infection Exacerbates Ischemic Brain Damage via a CCL5 (Regulated on Activation, Normal T-Cell Expressed and Secreted)-Mediated Proinflammatory Response in Mice. J Neurosci 30: 10086-10095. doi: 10.1523/JNEUROSCI.1227-10.2010
[3]	Imig JD, Ryan MJ (2013) Immune and Inflammatory Role in Renal Disease. Compr Physiol 3: 957-976.
[4]	Momiyama Y, Ohmori R, Fayad ZA, et al. (2012) Associations between serum lipoprotein(a) levels and the severity of coronary and aortic atherosclerosis. Atherosclerosis 222: 241-244. doi: 10.1016/j.atherosclerosis.2012.02.008
[5]	Kalaivani V, Appukuttan PS (2015) Plasma lipoprotein(a) size polymorphism and function: apo(a) subunit size determines galectin-1 recognition and apoB subunit epitope masking. Open J Biochem 2015: 22-33. doi: 10.15764/BIOC.2015.01003
[6]	Pepin JM, O'Neil JA, Hoff HF (1991) Quantification of apo[a] and apoB in human atherosclerotic lesions. J Lipid Res 32: 317-327.
[7]	van Dijk RA, Kolodgie F, Ravandi A, et al. (2012) Differential expression of oxidation-specific epitopes and apolipoprotein(a) in progressing and ruptured human coronary and carotid atherosclerotic lesions. J Lipid Res 53: 2773-2790.
[8]	Krebs P, Scandella E, Bolinger B, et al. (2007) Chronic Immune Reactivity Against Persisting Microbial Antigen in the Vasculature Exacerbates Atherosclerotic Lesion Formation. Arterioscler Thromb Vasc Biol 27: 2206-2213. doi: 10.1161/ATVBAHA.107.141846
[9]	Kabat EA, Berg D (1953) Dextran; an antigen in man. J Immunol 70: 514-532.
[10]	Geetha M, Annamma KI, Mathai J, et al. (2007) Normal human plasma anti-beta-glucoside antibody has markedly elevated IgA content and binds fungal and yeast polysaccharides. Immunol Invest 36: 73-83.
[11]	Tsuda H, Yamashita Y, Toyoshima K, et al. (2000) Role of serotype-specific polysaccharide in the resistance of Streptococcus mutans to phagocytosis by human polymorphonuclear leukocytes. Infect Immun 68: 644-650. doi: 10.1128/IAI.68.2.644-650.2000
[12]	Sabarinath PS, Appukuttan PS (2015) Immunopathology of desialylation: human plasma lipoprotein(a) and circulating anti-carbohydrate antibodies form immune complexes that recognize host cells. Mol Cell Biochem 403:13-23.
[13]	Sandrin MS, Vaughan HA, Xing PX, et al. (1997) Natural human anti-Gal alpha(1,3)Gal antibodies react with human mucin peptides. Glycoconj J 14: 97-105. doi: 10.1023/A:1018521217276
[14]	Geetha M, Kalaivani V, Sabarinath PS, et al. (2014) Plasma anti-α-galactoside antibody binds to serine- and threonine-rich peptide sequence of apo(a) subunit in Lp(a). Glycoconj J 31: 289-298.
[15]	Mandagini G, Subramanian SP, Vasantha K, et al. (2013) Human plasma anti-α-galactoside antibody forms immune complex with autologous lipoprotein(a). Immunol Invest 42: 324-340.
[16]	Appukuttan PS, Surolia A, Bachawat BK (1977) Isolation of two galactose-binding proteins from Ricinus communis by affinity chromatography. Indian J Biochem Biophys 14: 382-384.
[17]	Paul A, Antony M, Mathai J, et al. (2011) High polymeric IgA content facilitates recognition of microbial polysaccharide-natural serum antibody immune complexes by immobilized human galectin-1. Immunol Lett 136: 55-60.
[18]	Baues RJ, Gray GR (1977) Lectin purification on affinity columns containing reductively aminated disaccharides. J Biol Chem 252: 57-60.
[19]	Weir DM (1986) Handbook of experimental immunology. Blackwell Scientific Publications, Oxford; Boston.
[20]	Bradford MM (1976) A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 72: 248-254.
[21]	Travis J, Bowen J, Tewksbury D, et al. (1976) Isolation of albumin from whole human plasma and fractionation of albumin-depleted plasma. Biochem J 157: 301-306. doi: 10.1042/bj1570301
[22]	Hudson L, Hay FC (1980) Practical immunology, 2. ed. Blackwell, Oxford.
[23]	George G, Geetha M, Appukuttan PS (2015) Antigen-Induced Activation of Antibody Measured by Fluorescence Enhancement of FITC Label at Fc. J Fluoresc 25: 1493-1499. doi: 10.1007/s10895-015-1640-z
[24]	George G, Antony M, Mathai J, et al. (2016) Periodontitis and Inflammation: Plasma High Titer Naturally Occurring Anti-Glucan Antibodies Form Immune Complex with Streptococcus mutans Antigen. Mod Res Inflamm 05: 45-54. doi: 10.4236/mri.2016.53005
[25]	Galili U, Korkesh A, Kahane I, et al. (1983) Demonstration of a natural antigalactosyl IgG antibody on thalassemic red blood cells. Blood 61: 1258-1264.
[26]	Gupta D, Kaltner H, Dong X, et al. (1996) Comparative cross-linking activities of lactose-specific plant and animal lectins and a natural lactose-binding immunoglobulin G fraction from human serum with asialofetuin. Glycobiology 6: 843-849. doi: 10.1093/glycob/6.8.843
[27]	Dong X, Andre S, Hofer B, et al. (1997) Disease type-associated increases of the plasma levels and ligand expression for natural alpha- or beta-galactoside-binding immunoglobulin G subfractions in patients with lung cancer. Int J Oncol 10: 709-719.
[28]	Roozbeh J, Merat A, Bodagkhan F, et al. (2011) Significance of serum and urine neuraminidase activity and serum and urine level of sialic acid in diabetic nephropathy. Int Urol Nephrol 43: 1143-1148. doi: 10.1007/s11255-010-9891-8
[29]	Colwell JA, Lopes-Virella M, Halushka PV (1981) Pathogenesis of atherosclerosis in diabetes mellitus. Diabetes Care 4: 121-133. doi: 10.2337/diacare.4.1.121
[30]	Sheela B, George G, Mandagini G, et al. (2016) Plasma anti-α-galactoside antibody mediates lipoprotein(a) binding to macrophages. Glycoconj J 33: 953-961.
[31]	Kronenberg F, Kronenberg MF, Kiechl S, et al. (1999) Role of lipoprotein(a) and apolipoprotein(a) phenotype in atherogenesis:prospective results from the Bruneck study. Circulation 100: 1154-1160. doi: 10.1161/01.CIR.100.11.1154
[32]	Kalaivani V, Appukuttan PS (2014) Circulating Lp(a):LDL complexes contain LDL molecules proportionate to Lp(a) size and bind to galectin-1: a possible route for LDL entry into cells. Lipids 49: 1101-1113.

Reader Comments

Your name:*

Email:*
© 2017 the Author(s), licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0)