Desialylation of dying cells with catalytically active antibodies possessing sialidase activity facilitate their clearance by human macrophages

Abstract

OTHER ARTICLES PUBLISHED IN THIS SERIES Dying autologous cells as instructors of the immune system. Clinical and Experimental Immunology 2015, 179: 1-4. Anti-dsDNA antibodies as a classification criterion and a diagnostic marker for systemic lupus erythematosus: critical remarks. Clinical and Experimental Immunology 2015, 179: 5-10. The effect of cell death in the initiation of lupus nephritis. Clinical and Experimental Immunology 2015, 179: 11-16 SummaryRecently we reported the first known incidence of antibodies possessing catalytic sialidase activity (sialidase abzymes) in the serum of patients with multiple myeloma and systemic lupus erythematosus (SLE). These antibodies desialylate biomolecules, such as glycoproteins, gangliosides and red blood cells. Desialylation of dying cells was demonstrated to facilitate apoptotic cell clearance. In this study we assessed the possibility to facilitate dying cell clearance with the use of F(ab)2 fragments of sialidase abzymes. Two sources of sialidase abzymes were used: (i) those isolated from sera of patients with SLE after preliminary screening of a cohort of patients for sialidase activity; and (ii) by creating an induced sialidase abzyme through immunization of a rabbit with synthetic hapten consisting of a non-hydrolysable analogue of sialidase reaction conjugated with bovine serum albumin (BSA) or keyhole limpet haemocyanin (KLH). Antibodies were purified by ammonium sulphate precipitation, protein-G affinity chromatography and size exclusion-high performance liquid chromatography (HPLC-SEC). Effect of desialylation on efferocytosis was studied using human polymorphonuclear leucocytes (PMN), both viable and aged, as prey, and human monocyte-derived macrophages (MoMa). Treatment of apoptotic and viable prey with both disease-associated (purified from blood serum of SLE patients) and immunization-induced (obtained by immunization of rabbits) sialidase abzymes, its F(ab)2 fragment and bacterial neuraminidase (as positive control) have significantly enhanced the clearance of prey by macrophages. We conclude that sialidase abzyme can serve as a protective agent in autoimmune patients and that artificial abzymes may be of potential therapeutic value.

Two‐step chromatography purification of IgGs possessing sialidase activity from human blood serum

“…Recently, we also created artificial sialidase abzyme by means of rabbit immunization with a synthetic hapten consisting of nonhydrolyzable inhibitor of sialidase reaction conjugated with bovine serum albumin (Bilyy et al ., ). Treatment of the apoptotic and viable prey with both natural (purified from blood serum of SLE patient) and artificial (obtained by rabbits immunization) sialidase‐like IgGs and their F(ab) 2 fragments significantly enhanced the prey clearance by the macrophages (Tomin et al ., ). In order to purify these ‘natural’ and ‘artificial’ abzymes, a typical procedure including precipitation of IgGs with ammonium sulfate from blood serum was applied, and then followed by antibody purification using Protein‐G affinity and HPLC size‐exclusion chromatography (Bilyy et al ., ; Tomin et al , ).…”

Anti-DNA antibody mediated catalysis is isotype dependent

“…Increasing evidence suggests important functional roles for catalytic antibodies in homeostasis, autoimmune disease, and protection against infection (Paul et al, 2012; Tomin et al, 2015; Barrera et al, 2009; Nevinsky et al, 2010). Interestingly, in autoimmunity, natural antibody-enzymes (abzymes) can have both beneficial and detrimental effects, depending on the specific disease and the targets they cleave (for comprehensive review, see Belogurov et al, 2009).…”

Cutting back on the carbs

“…The in vitro effects are promising, and suggest several avenues for further research. For example, it may be of interest to apply human sialidase enzymes or abzymes (26,27) to the strategy because the V. cholerae enzyme source is likely to be immunogenic. In addition, alternative constructs using carriers other than the 150-kDa anti-HER2 antibody may expand applications of the approach, and potentially address issues surrounding penetration and retention of the conjugate within tumor masses.…”