Enhanced inflammatory activity of endometriotic lesions from the rectovaginal septum

Abstract

Endometriosis is characterised by the growth of ectopic lesions at multiple locations outside the uterine cavity and may be considered a collection of distinct but related conditions. The exact aetiology of endometriosis is still not clear although a role for inflammation is increasingly accepted. We therefore investigated the inflammatory activity of eutopic tissue and that of the matching ectopic lesions from different locations by measuring the genetic expression of inflammatory chemokines and cytokines. The gene expression in matching eutopic and ectopic tissue was compared, as was the gene expression in lesions from different locations. A significantly higher mRNA expression of the chemokines ENA-78 and RANTES and the cytokines IL-6 and TNF α was observed in endometriotic lesions of the rectovaginal septum (RVS) compared to that of matching eutopic tissue. Comparisons across lesion locations showed a significantly higher expression of IL-6 and TNF α in the RVS compared to lesions from either the ovaries or the peritoneum. These results show that the production of some inflammatory chemokines and cytokines is significantly increased in the ectopic endometrial tissue compared to matching eutopic tissue. Furthermore, IL-6 and TNF α are produced in significantly higher quantities in RVS lesions compared to other lesions.

Figure 1

Chemokine production in eutopic endometrium and matching ectopic endometriotic lesions from different locations. (a) No significant difference was observed in the mRNA expression of MCP-1. (b) ENA-78 mRNA expression was significantly stronger in the RVS lesions compared to its matching eutopic tissue. (c) No significant difference in IL-8 mRNA expression was observed between the eutopic endometrium and the ectopic lesions from different locations. (d) RANTES expression was significantly higher in the RVS lesions compared to the eutopic endometrium. All values are represented by mean ± SEM. * < .05, ** < .01.

Figure 2

Inflammatory cytokine mRNA expression in eutopic and matching ectopic endometriotic lesions from different locations. (a) The mRNA expression of TNFα was significantly higher in the peritoneal and RVS lesions compared to their matching eutopic endometrium. (b) The mRNA expression of IL-6 was significantly higher only in the RVS lesions. All values are represented by mean ± SEM. * < .05, ** < .01, **** < .0001.

Figure 3

Comparison of cytokine and chemokine concentrations in endometriotic lesions from different locations. A comparison of the mRNA expression between endometriotic lesions from different locations indicated that TNFα expression in the RVS was significantly higher than expression in the ovarian lesions. IL-6 mRNA expression was significantly higher in the RVS than either the ovarian or the peritoneal lesions. There was no significant difference between the lesions with any of the other cytokines. All values are represented by mean ± SEM. * < .05, **** < .0001.