Identification of anti‐α‐enolase autoantibody as a novel serum marker for endometriosis

Abstract

Diagnosis of endometriosis needs invasive maneuvers. New serum marker that possesses both high sensitivity and high specificity has long been desired. To establish novel serum marker for endometriosis, serum autoantibodies (autoAbs) were investigated using proteomic approach. AutoAbs in sera of endometriotic patients and healthy controls were analyzed using a mesothelial cell line, 2-DE and Western blotting. Proteins in reacted spots were identified using MALDI TOF-MS with MASCOT analysis. ELISAs were established using recombinant proteins and autoAb-titers were estimated in sera of endometriotic patients, disease and healthy controls. Several autoAbs were identified. Anti-α-enolase (Eno1)-autoAb levels in endometriotic patients were significantly elevated compared with both healthy and disease controls. Sensitivity and specificity of serum anti-Eno1-autoAb was nearly comparable to serum CA125. When anti-Eno1-autoAb and CA125 assays were combined, diagnostic sensitivity and accuracy improved. Serum anti-Eno1-autoAb can be a new serum endometriotic marker and it is useful as a supplement assay for CA125. This study validates further clinical evaluation of this novel marker.

Serum anti-PDIK1L autoantibody as a novel marker for endometriosis

“…In addition to our previous report (13), this study suggests a possibility that autoAbs such as anti-a-enolase autoAb and anti-PDIK1L-autoAb can be good markers for endometriosis. This supports a concept that endometriosis possesses an autoimmune nature (9,(11)(12)(13)17).…”

“…The 2D gel electrophoresis and Western blotting were performed as reported previously (13,15,16). Briefly, MRC-5 cells were solubilized with 8M urea (GE Healthcare, Tokyo, Japan), 2% NP-40 (Nacalai Tesque), 2% 2-ME (Sigma-Aldrich, Tokyo, Japan), 10 mM phenylmethanesulfonylfluoride or phenylmethylsulfonyl fluoride (Sigma-Aldrich).…”

“…For protein identification, peptide mass fingerprinting was used employing Voyager DE-PRO (Applied Biosystems, Tokyo, Japan) as reported previously (13,16). Identified spots on CBB-stained 2D gels were excised and incubated with 50% acetonitrile (Nacalai Tesque).…”

“…ELISAs for autoAbs were developed using recombinant proteins for the solid phase (13,16). The recombinant proteins as GST-PDIK1L protein were diluted with carbonate buffer and added to the wells of an ELISA plate (Nunc Immunoplate, Thermo Scientific, Kanagawa, Japan) at a final concentration of 1 mg/mL.…”

“…Accordingly, autoantibodies (autoAbs) as serum biomarkers for the diagnosis of endometriosis have been investigated: anti-a-enolase-autoAb was found to be useful (13); however, the sensitivity of anti-a-enolaseautoAb was just comparable to CA125.…”