The Serum Levels of the Soluble Factors sCD40L and CXCL1 Are Not Indicative of Endometriosis

Abstract

Endometriosis is a benign but troublesome gynecological condition, characterized by endometrial-like tissue outside the uterine cavity. Lately, the discovery and validation of noninvasive diagnostic biomarkers for endometriosis is one of the main priorities in the field. As the disease elicits a chronic inflammatory reaction, we focused our interest on two factors well known to be involved in inflammation and neoplastic processes, namely, soluble CD40 Ligand and CXCL1, and asked whether differences in the serum levels of sCD40L and CXCL1 in endometriosis patients versus controls can serve as noninvasive disease markers. A total of n = 60 women were included in the study, 31 endometriosis patients and 29 controls, and the serum levels of sCD40L and CXCL1 were measured by enzyme-linked immunosorbent assay. Overall, there were no statistically significant differences in the levels of expression of both sCD40L and CXCL1 between patients and controls. This study adds useful clinical data showing that the serum levels of the soluble factors sCD40L and CXCL1 are not associated with endometriosis and are not suitable as biomarkers for disease diagnosis. However, we found a trend toward lower levels of sCD40L in the deep infiltrating endometriosis subgroup making it a potentially interesting target worth further investigation.

Figure 1

Patients with endometriosis did not show a statistically significant change in the serum levels of both sCD40L and CXCL1. Boxplots showing the comparison between the levels of expression of sCD40L (a) and CXCL1 (b) in serum of patients with endometriosis versus controls. The levels are presented as log 10 and the p values are indicated above each plot. Arrows next to the boxplots indicate mean ± standard deviation.

Figure 2

The sCD40L and CXCL1 secretion is disease stage independent. Levels of sCD40L (a) and CXCL1 (b) in the control group and based on the different stages of endometriosis classified by rAFS stage in the endometriosis patients, with no statistically significant differences. C: control group, I/II: endometriosis rAFS minimal-to-mild disease, and III/IV: endometriosis rAFS moderate-to-severe disease.

Figure 3

The serum levels of sCD40L and CXCL1 are not differentially regulated during the menstrual cycle in patients with endometriosis versus controls. Boxplots showing levels of sCD40L (a) and CXCL1 (b) among endometriosis patients and controls by menstrual cycle phases, with no statistically significant differences. CP: control proliferative phase, CS: control secretory phase, EP: endometriosis proliferative phase, and ES: endometriosis secretory phase.

Figure 4

Patients with deep infiltrating endometriosis (DIE) show a tendency of reduced sCD40L levels and no changes in the levels of CXCL1 in serum when compared to controls. Boxplots showing levels of sCD40L (a) and CXCL1 (b) among controls and endometriosis patients with DIE. The number of samples for each group is given in brackets on the x-axis and the p values of the comparison between the groups are shown below each graph. C: control, DIE: deep infiltrating endometriosis.