Hepcidin as a key regulator of iron homeostasis triggers inflammatory features in the normal endometrium

Menstrual blood, containing high iron levels, can undergo retrograde transport into the abdominal cavity. Excess iron causes oxidative stress and inflammation. Iron metabolism is regulated by hepcidin, and serum hepcidin levels are increased in patients with endometriosis; however, the functions of hepcidin in normal endometrium remain unclear. We therefore aimed to examine hepcidin concentrations in patients with endometriosis and to determine if iron accumulation and hepcidin increased the production of reactive oxygen species (ROS) and inflammation in normal endometrial cells. We determined hepcidin levels in peritoneal fluid and menstrual blood from patients with and without endometriosis (25/16 and 15/15 patients, respectively). We also examined the effects of hepcidin on ferroportin expression, iron accumulation, and ROS generation in normal endometrial stromal cells (NESCs) from 20 women who underwent surgery for uterine leiomyoma, using immunohistochemistry and immunofluorescence analyses and analyzed its effect on the expression of inflammatory cytokines by real-time polymerase chain reaction. There was no significant difference in iron concentrations in menstrual blood or peritoneal fluid between women with and without endometriosis; however, women with endometriosis had significantly higher hepcidin levels in menstrual blood. Hepcidin reduced the expression of ferroportin in NESCs and promoted the accumulation of ferrous iron. Hepcidin plus ferrous iron increased the production of ROS and inflammatory cytokines compared with ferrous iron alone. These results indicate that women with endometriosis have high hepcidin levels in menstrual blood, leading to increased iron production, oxidative stress, and inflammation, which may, in turn, promote the development of endometriosis.

Influence of interleukin-8 polymorphism on endometriosis-related pelvic pain

Endometriosis presents a pro-inflammatory microenvironment influenced by cytokines, such as interleukin (IL)-8, which expression may be influenced by genetic polymorphisms. Therefore, we aimed to investigate the role of interleukin (IL)-8 rs4073 polymorphism in endometriosis' development and its related symptoms. A case-control study was conducted with 207 women with endometriosis and 193 healthy controls. Polymorphism was genotyped using a TaqMan validated assay. Associations were evaluated by binary logistic regression, using odds ratios (OR) and 95 % confidence intervals (CI), and P ≤ 0.05 was considered significant. Cases were younger (36 ± 6.8 versus 39 ± 8.4) and had lower body mass index (26.5 ± 5.3 versus 35.7 ± 6.3 Kg/m2) than controls (P < 0.001). Higher prevalence of symptoms and infertility was observed in cases, compared to controls (P < 0.001). Minor allele frequencies of IL-8 rs4073 (T) were 42.3 % and 39.9 % for cases and controls, respectively, and no associations were found between IL and 8 rs4073 polymorphism and endometriosis' prevalence or staging. However, the polymorphism was associated with chronic pelvic pain among cases (OR = 0.54; 95 %CI = 0.29-0.98). The IL-8 rs4073A > T polymorphism may contribute to lower IL-8 expression and, consequently, decrease endometriosis-related pelvic pain. These findings can support the early diagnosis of endometriosis' painful symptoms, preventing its complications, and allowing an individualized treatment.

Low-Nutrient Environment-Induced Changes in Inflammation, Cell Proliferation, and PGC-1α Expression in Stromal Cells with Ovarian Endometriosis

Although nutrient status plays an important role in cell metabolism, its significance in endometriosis is obscure. Herein, we investigated the effects of a low-nutrient microenvironment on endometriosis. Stromal cells (SCs) from ovarian endometrioma (OESCs) or normal endometrium without endometriosis (NESCs) were isolated and cultured. A low-nutrient microenvironment was replicated by replacing the culture medium with Hank's balanced salt solution. OESC and NESC proliferation under the low-nutrient condition was measured. The expression of exacerbating factors in endometriosis under the low-nutrient condition was examined at the mRNA and protein levels. OESCs showed higher proliferation than NESCs under the low-nutrient condition. In OESCs, the low-nutrient condition upregulated the mRNA expression of vascular endothelial growth factor (VEGF), interleukin-6 and -8, aromatase, Bcl-2, and peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) and downregulated that of BAX and induced transcription of PI.3, PII, and exon II. Western blotting revealed elevated VEGF and PGC-1α expression under the low-nutrient condition in OESCs. These changes coincided with the elevated expression of PGC-1α, which was reduced at the mRNA level upon nutrient status rescue. Endometriosis is exacerbated by altered angiogenesis, inflammation, anti-apoptosis, and local estrogen production while trying to survive under a low-nutrient microenvironment; it may be attributed to PGC-1α-mediated metabolic mechanisms.

Revisiting estrogen-dependent signaling pathways in endometriosis: Potential targets for non-hormonal therapeutics

Endometriosis is an estrogen-dependent gynecologic disease. Endometriotic cells survive in oxidative stress and hypoxic environments. The aim of this review is to reconsider new therapeutic strategies for endometriosis by focusing on estrogen signaling, ROS production and scavenging, and mitochondrial metabolism. Each keyword alone or in combination was used to search from PubMed and Embase by applying the filters of the title and the publication years between January 2000 and May 2020. Abnormal epigenetic marks of estrogen receptors (ERs) in endometriosis cause overexpression of ERβ, progesterone resistance, inflammation, anti-apoptosis, and mitochondrial metabolic modification. In addition to hormonal action, estrogen is involved in various functions such as mitochondrial biosynthesis and energy metabolism. Estrogen works with its downstream target genes to modulate mitochondrial gene expression, regulate ROS production, and affect mitochondrial biology, including ATP production, antioxidant defenses, mitochondrial biosynthesis, quality control, and energy-transducing capacity. Endometriosis can shift mitochondrial metabolism from oxidative phosphorylation to aerobic glycolysis. This metabolic conversion suppresses ROS production and thus activates the survival signal of endometriotic cells. Therefore, molecules associated with aerobic glycolysis and mitochondrial metabolism are considered therapeutic targets for endometriosis. In conclusion, estrogen downstream target genes involved in mitochondrial metabolic biosynthesis may be potential targets for non-hormonal treatment of endometriosis.