Gene expression of leptin and long leptin receptor isoform in endometriosis: a case-control study

Leptin concentrations in endometriosis: A systematic review and meta-analysis

INTRODUCTION

Endometriosis is an inflammatory condition, affecting mainly women of reproductive age. Leptin is a regulator of food intake and energy expenditure, posing pleiotropic actions, and regulating immunity and fertility. The aim of this study was to systematically review the literature regarding leptin concentrations in biological fluids and tissues of women with endometriosis, and to investigate and propose a possible role of leptin in the pathophysiology of endometriosis.

MATERIALS AND METHODS

A systematic search of the literature was conducted in two electronic databases (MEDLINE, COCHRANE) and grey literature for original research articles on humans, published in any language.

RESULTS

Twenty-nine studies with 1291 women with endometriosis and 1664 controls were included in the systematic review. Peritoneal fluid and follicular fluid leptin concentrations were higher in endometriosis compared with control group [mean difference (MD) 7.10, 95 % confidence interval (CI) 4.76 to 9.44 ng/mL, 18 studies), (MD 1.35, 95 % CI 0.54-2.17 ng/ml, 2 studies) respectively. No differences were evident in serum (MD 0.92, 95 % CI -0.84 to 2.68 ng/mL, 12 studies) or plasma (MD -0.95, 95 % CI -4.63 to 2.72 ng/mL, 3 studies) between the groups. No meta-analysis was conducted for ovarian tissue leptin (2 studies).

CONCLUSIONS

This meta-analysis provided evidence for increased leptin concentrations in both peritoneal fluid and follicular fluid of women with endometriosis compared with control; these differences were not present in the serum or plasma. The above results support a potential pathophysiologic role for leptin in the local microenvironment while declines its use as a blood diagnostic marker. Furthermore, we propose a possible role of leptin in the pathophysiology of endometriosis.

PDCD4 suppresses proliferation, migration, and invasion of endometrial cells by inhibiting autophagy and NF-κB/MMP2/MMP9 signal pathway

Endometriosis (EM) is a kind of estrogen-dependent disease in reproductive-age women. Ovarian EM is the most common type. Although EM is a benign disease, it shares many similar features with cancers. Programmed cell death 4 (PDCD4), a newly identified tumor suppressor, plays an important role in inhibiting tumorigenesis and tumor progression at the transcriptional and translational levels. To explore the roles of PDCD4 in EM, we detected the expression of PDCD4 in control endometrium and eutopic/ectopic endometrium of ovarian EM patients, and analyzed the effects of PDCD4 on the biological behaviors of endometrial cell lines and primary endometrial cells. The results demonstrated that PDCD4 was downregulated in eutopic and ectopic endometrium of EM patients compared with control endometrium. PDCD4 effectively inhibited the proliferation and colony-forming ability of endometrial cells maybe by inhibiting cell autophagy. In addition, PDCD4 also suppressed the migration and invasion ability of endometrial cells, the mechanism may be related to NF-κB/MMP2/MMP9 signal pathway. Taken together, these results suggest that PDCD4 could be involved in the pathogenesis of EM, and provide a novel approach to target the aberrant PDCD4 expression in EM.

Circulating and peritoneal fluid interleukin-6 levels and gene expression in pelvic endometriosis

Current data are inconsistent regarding the association between interleukin-6 (IL-6), a marker of acute phase inflammation, and pelvic endometriosis. The aim of the present study was to assess IL-6 levels in serum and peritoneal fluid (PF), as well as IL-6 gene expression in adipose tissue (AT) and endometrial samples in pelvic endometriosis. A total of 30 patients with endometriosis and 18 women with a normal pelvis were enrolled in this case-control study. IL-6 levels in PF and serum were determined using a human enzyme-linked immunosorbent assay and IL-6 gene expression was evaluated using reverse transcription-quantitative polymerase chain reaction. It was observed that IL-6 levels in the PF were higher in patients with endometriosis than in the control group (P=0.047) and patients with stage III/IV endometriosis exhibited higher IL-6 levels in the PF than those with stage I/II endometriosis and the control group (P<0.001). Furthermore, a strong correlation between PF IL-6 levels and the revised American Society for Reproductive Medicine score for endometriosis severity was identified (r=0.77; P<0.001). IL-6 gene expression did not differ significantly between endometriosis and control groups in endometrial samples or in AT of both groups. The results of the current study suggest that there may be an association between IL-6 and the presence and severity of pelvic endometriosis. The source of this higher IL-6 seems not to be specifically related to regional AT.

Low Body Mass Index in Endometriosis Is Promoted by Hepatic Metabolic Gene Dysregulation in Mice

The gynecological disease endometriosis is characterized by the deposition and proliferation of endometrial cells outside the uterus and clinically is linked to low body mass index (BMI). Gene expression in the liver of these women has not been reported. We hypothesized that endometriosis may impact hepatic gene expression, promoting a low BMI. To determine the effect of endometriosis on liver gene expression, we induced endometriosis in female mice by suturing donor mouse endometrium into the peritoneal cavity and measuring the weight of these mice. Dual-energy X-ray absorptiometry (DEXA) scanning of these mice showed lower body weight and lower total body fat than controls. Microarray analysis identified 26 genes differentially regulated in the livers of mice with endometriosis. Six of 26 genes were involved in metabolism. Four of six genes were upregulated and were related to weight loss, whereas two genes were downregulated and linked to obesity. Expression levels of Cyp2r1, Fabp4, Mrc1, and Rock2 were increased, whereas Igfbp1 and Mmd2 expression levels were decreased. Lep and Pparg, key metabolic genes in the pathways of the six genes identified from the microarray, were also upregulated. This dysregulation was specific to metabolic pathways. Here we demonstrate that endometriosis causes reduced body weight and body fat and disrupts expression of liver genes. We suggest that altered metabolism mediated by the liver contributes to the clinically observed low BMI that is characteristic of women with endometriosis. These findings reveal the systemic and multiorgan nature of endometriosis.

Leptin, its receptor and aromatase expression in deep infiltrating endometriosis

Background

The aim of this study was to evaluate the leptin levels in the serum and peritoneal fluid (PF) and the protein expression in three different peritoneal ectopic implants in patients who underwent surgery for deep infiltrating endometriosis.

Methods

All patients had been treated at the Department of Gynecology of the Pedro Ernesto University Hospital, Rio de Janeiro. The study group consisted of 15 patients who underwent surgery for adnexal masses and infertility, while the control group consisted of ten women who underwent surgery for tubal ligation. Peritoneal fluid and samples tissues were collected during surgery. Serum samples were obtained before anesthesia. In this study, the leptin levels in the serum and peritoneal fluid (PF) were evaluated by ELISA. The protein expression of leptin and its receptors (ObR) and aromatase enzyme were evaluated by Western blot analysis of the intestine, uterosacral ligament and vaginal septum in the ectopic implants. The t-test and one-way ANOVA with Holm-Sìdak post-test were used, and p < 0.05 was considered to be statistically significant.

Results

Compared to the controls, the serum leptin levels (control = 14.7 ng/mL ± 2.63, endometriosis = 19.2 ng/mL ± 1.84, p < 0.0001) were increased, while in PF, there was no difference (control = 6.68 ng/mL ± 0.43, endometriosis = 7.71 ng/mL ± 0.59, p = 0.18). Comparing women with and without ovarian implants, the leptin levels in both the serum and PF were significantly higher in women without ovarian implants (serum: with ovarian implant = 15.85 ± 1.99; without ovarian implant = 23.14 ± 2.60; ng/mL, p = 0.04; PF: with ovarian implant = 4.28 ± 1.30; without ovarian implant = 11.18 ± 2.98;ng/mL, p = 0.048). The leptin, ObR and aromatase protein expression levels were increased in lesions in the vaginal septum and were decreased in the intestine lesions.

Conclusion

This study reports several interesting associations between the leptin levels in serum, peritoneal fluid, and tissue samples and the localization of the ectopic endometrium. Although this study does not provide a clear picture of the role of leptin in the development and progression of peritoneal implants, it contributed new data that might be useful to elucidating the enigma that is the role of leptin in endometriosis disease.

Increased expression of the leptin receptor in human ovaries affected by endometrioma and detection of high levels of leptin in the ovarian endometriomal fluid

Background

This study was designed to investigate leptin levels in the fluid in ovarian endometriomas (OEs) and to compare the expression of leptin and its receptors (OBR) in ovarian tissue affected by endometrioma in infertile women to its expression in the normal ovarian tissue of fertile controls without endometriosis.

Methods

In this case–control observational study, ovarian tissue, blood samples and peritoneal fluid were obtained from 20 women (10 fertile controls without endometriosis or any ovarian disease, who were undergoing tubal ligation surgery, and 10 infertile women with severe endometriosis and OE). The ovarian endometriomal fluid (EF) was aspirated, and peritoneal-implant (PI) biopsies were performed. The tissues removed during the surgeries were immediately frozen in liquid nitrogen to determine expression levels by western blot and leptin levels by ELISA.

Results

OBR was expressed at higher levels in the ovarian tissue affected by endometrioma than in the normal ovarian tissue (control = 0.38 ± 0.05, study = 0.60 ± 0.09, p = 0.03), but there was no significant difference in leptin levels between these groups (control = 0.57 ± 0.1, study = 0.35 ± 0.1, p = 0.18). Positive and significant correlations were observed between leptin and OBR in the OE (r = 0.85, p = 0.004) and in the PI (r = 0.87, p = 0.001). ELISA results demonstrate a greater leptin concentration within the EF compared with the serum and the PF (serum = 14.25 ± 1.63, PF = 5.98 ± 2.0, EF = 73.8 ± 16.2, p = 0.0001), but there was no correlation between these variables. A positive, significant and strong correlation was observed between PF leptin levels and the expression of leptin and OBR in PI (leptin: r = 0.78, p = 0.007/OBR: r = 0.68, p = 0.04) and between the EF leptin levels and the expression of leptin and OBR in the OE (leptin: r = 0.88, p = 0.008/OBR: r = 0.89, p = 0.005).

Conclusions

These data suggest that leptin may play an important role in the physiopathology of OE through a modulatory interaction with its active receptor.