Anti α-enolase antibody is a novel autoimmune biomarker for unexplained recurrent miscarriages

Abstract

Background We recently demonstrated the increased abundance of anti-trophoblast antibodies (ATAB) in sera of patients with unexplained recurrent miscarriages (uRM). Further, the ATAB-positive sera bound to JEG-3 human choriocarcinoma cells in vitro, resulting in decreased productions of β-human chorionic gonadotropin (β-hCG) and progesterone in these cells. However, the specific antigenic epitopes of ATAB have remained unknown. Therefore, it was the aim of this study to determine specific targets of ATAB in uRM patients. Methods Potential targets of ATAB were analyzed by 2-dimensional difference gel electrophoresis (2D-DIGE) and mass spectrometry, and thereby identifying α-Enolase (ENO1). ATAB targeting of ENO1 was further confirmed in a competitive binding assay. Levels of anti-ENO1 antibodies as well as β-hCG and progesterone were quantified with enzyme-linked immunosorbent assay (ELISA). Additionally, expression of ENO1 was analyzed in first trimester placentas by immunohistochemistry and immunofluorescence analysis. Findings We here identified ENO1 as a prominent target of ATAB. Serum levels of anti-ENO1 antibodies were increased in ATAB-positive compared to ATAB-negative patients. Further, increased expression of ENO1 and its co-expression with β-arrestin was found in the extra villous trophoblasts of uRM patients in first trimester placentas. In vitro, anti-ENO1 antibodies decreased the secretion of β-hCG and progesterone in JEG-3 and primary human villous trophoblast cells. Interpretation Serum anti-ENO1 antibodies might be an autoimmune biomarker for uRM. Targeting the formation of anti-ENO1 antibodies or inhibition of ENO1 expression could potentially represent therapeutic strategies for these patients. Fund All authors declare no conflict of interest. Yao Ye was supported by the China Scholarship Council. Hellen Ishikawa-Ankerhold and Christian Schulz were supported by the SFB914, projects Z01 and A10. None of the rest authors has any conflict of interest to declare.

Identification and Validation of Serum Autoantibodies in Children with B-cell Acute Lymphoblastic Leukemia by Serological Proteome Analysis

“…In the validation stage, we proved that α-enolase and VDAC1 autoantibodies were new representative targets for distinguishing patients with B-ALL from normal controls. To the best of our knowledge,this study was the rst report of the existence of autoantibodies against α-enolase and VDAC1 in serum from children with B-ALL by a proteomic approach,nevertheless, the α-enolase autoantibody was not all speci c to B-ALL serum and were found in the serum of patients with other tumors,as well as α-enolase antibodies were found in some autoimmune diseases [29][30][31] .The mechanism which α-enolase and VDAC1 induce immune response in B-ALL is unclear.…”

Expression of Alpha-Enolase 1 (ENO1) in Villi from Patients with Recurrent Miscarriage and Its Effect on Proliferation and Invasion of Villous Trophoblasts

“…Targeting surface αenolase is a promising method for inhibiting tumor metastasis [12]. In addition, overexpression of ENO1 will increase the secretion of progesterone in granulosa cells cultured in vitro in goose follicles, suggesting that it may be related to corpus luteum function [13].…”

Influence of reproductively significant autoantibodies on the quality of oocytes, obtained embryos and the chances of implantation in Assisted Reproductive Technologies cycles. Literature review

“…Moreover, in vitro, antibodies against ENO1 inhibited the production of β-hCG and progesterone by the cells of the human villous trophoblast. Thus, the authors suggest that these antibodies may become a new autoimmune biomarker for recurrent miscarriage [25]. In addition, along with the presence of antibodies to enolase-1, elevated serum levels of proinflammatory cytokines such as IL-1β, TNF-α, and PGE2 were detected, negatively affecting the development of pregnancy [85].…”

“…In 2018, a group of German scientists conducted a study to identify antibodies involved in recurrent miscarriage. Using Western blotting and mass spectrometry, the authors discovered a new target for antibodies to trophoblast, namely enolase-1 (ENO1), which is detected in the JEG-3 choriocarcinoma cell line as well as in the tissue of extravillous trophoblast of the first trimester of pregnancy [25]. As known, ENO1 is a multifunctional glycolytic enzyme weighing 45-47 kDa and is abundant in the cytoplasm of different cells.…”