Neutrophil gelatinase-associated lipocalin serum level: A potential noninvasive biomarker of endometriosis?

Abstract

Neutrophil gelatinase-associated lipocalin (NGAL, also known as lipocalin-2) is an acute-phase protein expressed in many tissues and plays a role in cell proliferation, regulation, and epithelial-mesenchymal transformation. Therefore, this study aimed to investigate serum NGAL levels and endometrioma tissue expression in women with endometriosis. This cross-sectional study was conducted at a university hospital. The endometrioma group included 36 women who underwent ovarian cystectomy for endometrioma, which was compared with a control group (n = 36) of women who underwent ovarian cystectomy due to benign persistent cysts (follicle cyst, theca lutein cyst, and serous cystadenoma). NGAL levels were analyzed using both serum enzyme-linked immunosorbent assay analysis and immunohistochemical tissue staining. Serum C-reactive protein and CA-125 levels were also evaluated. NGAL serum levels were significantly higher in the endometrioma group than in the control group (P < .05). C-reactive protein and CA-125 levels were also significantly higher in the endometrioma group (P < .05) and were correlated with NGAL levels. Immunohistochemical staining for NGAL was also higher in the endometrioma group (P < .001). NGAL may be considered a potential noninvasive biomarker of endometriosis.

Figure 1.

(A) Serous ovarian cyst (H&Ex400), (B) NGAL expression in serous ovarian cyst (NGALx400), (C) endometriotic cyst (H&Ex400), and (D) NGAL expression in endometriotic cyst (NGALx400). NGAL = neutrophil gelatinase-associated lipocalin.

Figure 2.

Comparision of mean immunohistochemistry scores between endometrioma and control group (1.61 ± 0.54 endometrioma group vs 0.61 ± 0.80 control group, P < .001).

Figure 3.

Box plot analysis of NGAL, Ca-125 and CRP between endometrioma and control group. (P < .001 for NGAL,Ca-125 and CRP). CRP = C-reactive protein, NGAL = neutrophil gelatinase-associated lipocalin.