Vitamin D binding protein plays an important role in the progression of endometriosis

Proteomics approach to discovering non-invasive diagnostic biomarkers and understanding the pathogenesis of endometriosis: a systematic review and meta-analysis

BACKGROUND

Endometriosis is one of the most common gynaecological diseases, yet it lacks efficient biomarkers for early detection and unravels disease mechanisms. Proteomic profiling has revealed diverse patterns of protein changes in various clinical samples. Integrating and systematically analysing proteomics data can facilitate the development of biomarkers, expediting diagnosis and providing insights for potential clinical and therapeutic applications. Hence, this systematic review and meta-analysis aimed to explore potential non-invasive diagnostic biomarkers in various biological samples and therapeutic targets for endometriosis.

METHODS

Online databases, including Scopus, PubMed, Web of Science, MEDLINE, Embase via Ovid, and Google Scholar, were searched using MeSH terms. Two independent authors screened the articles, extracted the data, and assessed the methodological quality of the included studies. GO and KEGG analyses were performed to identify the pathways that were significantly enriched. Protein‑protein interaction and hub gene selection analyses were also conducted to identify biomarker networks for endometriosis.

RESULTS

Twenty-six observational studies with a total of 2,486 participants were included. A total of 644 differentially expressed proteins (180 upregulated and 464 downregulated) were identified from 9 studies. Proteins in peripheral blood exhibited a sensitivity and specificity of 38-100% and 59-99%, respectively, for detecting endometriosis, while proteins in urine had a sensitivity of 58-91% and specificity of 76-93%. Alpha-1-antitrypsin, albumin, and vitamin D binding proteins were significantly DEPs in both serum and urine. Complement C3 is commonly expressed in serum, menstrual blood, and cervical mucus. Additionally, S100-A8 is commonly expressed in both menstrual blood and cervical mucus. Haptoglobin is commonly detected in both serum and plasma, whereas cathepsin G is found in urine, serum, and plasma. GO and KEGG enrichment analyses revealed that proteoglycans in cancer pathways, which regulate cell-to-cell interactions, modulate the extracellular matrix, and promote the proliferation and invasion of endometrial cells, are commonly enriched in serum and urine.

CONCLUSION

This comprehensive study revealed potential proteomes that were significantly differentially expressed in women with endometriosis utilizing various non-invasive clinical samples. Exploring common differentially expressed proteins in various biological samples provides insights into the diagnosis and pathophysiology of endometriosis, as well as potential clinical and therapeutic applications.

Is the leptin/BMI ratio a reliable biomarker for endometriosis?

Background

The aim of this study was to analyze the concentration of leptin in peritoneal fluid and plasma and to assess their role as potential biomarkers in the diagnosis of endometriosis.

Materials & methods

Leptin adjusted for BMI (leptin/BMI ratio) was measured using surface plasmon resonance imaging (SPRI) biosensors. Patients with suspected endometriosis were included in the study. Plasma was collected from 70 cases, and peritoneal fluid from 67 cases. Based on the presence of endometriosis lesions detected during laparoscopy, patients were divided into a study group and a control group (patients without endometriosis).

Results

Leptin/BMI ratio in plasma did not differ between women with endometriosis and the control group (0.7159 ± 0.259 vs 0.6992 ± 0.273, p= 0,7988). No significant differences were observed in peritoneal leptin/BMI ratio levels in patients with and without endometriosis (0.6206 ± 0.258 vs 0.6215 ± 0.264, p= 0,9896). Plasma and peritoneal leptin/BMI ratios were significantly lower in women with endometriosis - related primary infertility compared to women with endometriosis without primary infertility (0.640 ± 0.502 vs 0.878 ± 0.623, p < 0.05). The difference was observed in case of primary infertility, but not in terms of the secondary one. No significant differences were noted between leptin/BMI ratio in the proliferative phase and the secretory phase (0.716 ± 0.252 vs 0.697 ± 0.288, p= 0,7785).

Conclusion

The results of present study do not support the relevance of leptin concentration determination as a biomarker of the endometriosis. Due to the limited number of samples in the tested group, further studies are needed to confirm its role.

Investigation of the Changes in Concentrations of Vitamin D-Binding Protein and Lactoferin in Plasma and Peritoneal Fluid of Patients with Endometriosis

An evaluation of the association between the concentrations of vitamin D-binding protein and lactoferrin in the plasma and peritoneal fluid may facilitate the elucidation of molecular mechanisms in endometriosis. Vitamin D-binding protein and lactoferrin concentrations were measured by ELISA in plasma and peritoneal fluid samples from 95 women with suspected endometriosis as classified by laparoscopy into groups with (n = 59) and without endometriosis (n = 36). There were no differences (p > 0.05) in the plasma and peritoneal fluid concentrations of vitamin D-binding protein and lactoferrin between women with and without endometriosis. In women with endometriosis, there was a significant correlation between plasma and peritoneal fluid vitamin D-binding protein concentrations (r = 0.821; p = 0.000), but there was no correlation between lactoferrin concentrations in those compartments (r = 0.049; p > 0.05). Furthermore, in endometriosis, lactoferrin was found to correlate poorly with vitamin D-binding protein (r= -0.236; p > 0.05) in plasma, while in the peritoneal fluid, the correlation between those proteins was significant (r = 0.399; p = 0.002). The characteristic properties of vitamin D-binding protein and lactoferrin and the associations between their plasma and peritoneal fluid concentrations found in women with endometriosis may provide a novel panel of markers to identify high-risk patients in need of further diagnostic measures.

Emerging hallmarks of endometriosis metabolism: A promising target for the treatment of endometriosis

Endometriosis, characterized by ectopic endometrium growth in the extrauterine environment, is one of the most notable diseases of the female reproductive system. Worldwide, endometriosis affects nearly 10 % of women in their reproductive years and causes a significant decline in quality of life. Despite extensive investigations of endometriosis over the past years, the mechanisms of endometriosis pathogenesis remain unclear. In recent years, metabolic factors have increasingly been considered factors in endometriosis. There is compelling evidence regarding the progress of endometriosis in the context of severe metabolic dysfunction. Hence, the curative strategies and ongoing attempts to conquer endometriosis might start with metabolic pathways. This review focuses on metabolic mechanisms and summarizes current research progress. These findings provide valuable information for the non-intrusive diagnosis of the disease and may contribute to the understanding of the pathogenesis of endometriosis.

The effect of vitamin D supplementation on clinical symptoms and metabolic profiles in patients with endometriosis

BACKGROUND

To our knowledge, data on the effects of vitamin D supplementation on clinical symptoms and metabolic profiles in patients with endometriosis are limited. This study was conducted to determine the effects of vitamin D supplementation on clinical symptoms and metabolic profiles in patients with endometriosis.

METHODS

The current randomized, double-blind, placebo-controlled trial was conducted among 60 patients (aged 18-40 years old) with endometriosis. Participants were randomly allocated into two groups (30 participants each group) to receive either 50,000 IU vitamin D or placebo each 2 weeks for 12 weeks.

RESULTS

Vitamin D supplementation significantly decreased pelvic pain (β - 1.12; 95% CI, -2.1, -0.09; p=.03) and total-/HDL-cholesterol ratio (β - 0.29; 95% CI, -0.57, -0.008; p=.04) compared with the placebo. Moreover, vitamin D intake led to a significant reduction in high-sensitivity C-reactive protein (hs-CRP) (β - 0.64 mg/L; 95% CI, -0.97, -0.30; p<.001) and a significant increase in total antioxidant capacity (TAC) (β 47.54 mmol/L; 95% CI, 19.98, 75.11; p=.001) compared with the placebo.

CONCLUSIONS

Overall, our study demonstrated that vitamin D intake in patients with endometriosis resulted in a significant improvement of pelvic pain, total-/HDL-cholesterol ratio, hs-CRP and TAC levels, but did not affect other clinical symptoms and metabolic profiles.

Vitamin D deficiency as a risk factor for endometriosis in Iranian women

PURPOSE

Vitamin D (Vit D), as an immunomodulator, has been hypothesized to play a critical role in the pathogenesis of endometriosis. Thus, in this study, we evaluated whether there is an association between 25-hydroxyvitamin D [25(OH)D] and susceptibility to endometriosis in Iranian women.

METHODS

Women at reproductive age, including 56 healthy women and 54 patients with endometriosis, were enrolled in the study. Serum levels of 25(OH)D, calcium, parathyroid hormone (PTH), and peritoneal fluid (PF) levels of 25(OH)D were assessed.

RESULTS

The serum and PF levels of 25(OH)D in the patients with endometriosis were significantly lower than the control group (P = 0.001 and P = 0.03, respectively). Subjects with serum levels of 25(OH)D lower than 20 ng/mL had a 2.7 times higher risk of endometriosis than people with 25(OH)D serum levels higher than 20 ng/mL (non-deficient) (OR = 2.7, 95 % confidence interval: 1.24-5.80, P = 0.01). The serum levels of calcium and PTH were significantly lower and higher in patients with endometriosis compared with controls, respectively (P < 0.001, P = 0.02, respectively). Also, the serum levels of 25(OH)D were lower in stages I-II endometriosis than stage III-IV; however, no significant difference was observed.

CONCLUSION

Our findings showed that people with Vit D deficiency are at higher risk of endometriosis.

Association between vitamin D and endometriosis: a systematic review

BACKGROUND

Endometriosis is one of the most common gynecological diseases of reproductive age, with a prevalence of 5-10% and grave consequences for quality of life and fertility. Vitamin D (vit D), a classic regulator of plasma calcium concentration and skeleton mineralization, is also an effective modulator of the immune system. Several studies suggest that immunologic properties attributed to vit D along with vit D receptor (VDR) expression in reproductive tissues may be involved in the pathogenesis of endometriosis.

OBJECTIVE

To systematically review the literature for the association between components of vit D metabolism and endometriosis.

MATERIALS AND METHODS

A systematic review of the literature published in the Medline and Cochrane Central databases was conducted for original research articles on humans, published in any language.

RESULTS

Twenty-one studies were included in the systematic review. Among them, 12 examined the relationship of endometriosis with vit D metabolites, eight with vit D-binding protein (VDBP), three with VDR polymorphisms, and two with vit D regulatory enzymes. There are discrepancies between the outcomes of the available literature publications.

CONCLUSIONS

This is a systematic attempt to collect, evaluate, and present the known data on the association between vit D and endometriosis. Given the heterogeneity and the diversity of the present studies, more research is required to elucidate the association between vit D and endometriosis.

Vitamin D Receptor Activation Influences NADPH Oxidase (NOX2) Activity and Protects against Neurological Deficits and Apoptosis in a Rat Model of Traumatic Brain Injury

Traumatic brain injury (TBI) is a worldwide phenomenon which results in significant neurological and cognitive deficits in humans. Vitamin D (VD) is implicated as a therapeutic strategy for various neurological diseases now. Recently, inhibition of the NADPH oxidase (NOX₂) was reported to protect against oxidative stress (ROS) production. However, whether alterations in NOX₂ expression and NOX activity are associated with calcitriol (active metabolite of VD) treatment following TBI remains unclear. In the present study, rats were randomly assigned to the sham, TBI, and calcitriol-treated groups. Calcitriol was administered intraperitoneally (2 μg/kg) at 30 min, 24 h, and 48 h after TBI insult. We observed that calcitriol treatment alleviated neurobehavioral deficits and brain edema following TBI. At the molecular levels, administration of calcitriol activated the expression of VDR and downregulated NOX₂ as well as suppressed apoptosis cell rate in the hippocampus CA1 region of TBI rats. In conclusion, our findings indicate that the protective effects of calcitriol may be related to the modulation of NADPH oxidase and thereby ultimately inhibited the progression of apoptosis. Calcitriol may be promising as a protective intervention following TBI, and more study is warranted for its clinical testing in the future.

Vitamin D receptor activation influences the ERK pathway and protects against neurological deficits and neuronal death

Previous studies have demonstrated that global cerebral ischemia (GCI) causes neurological deficits and neuronal cell apoptosis. Calcitriol, a biologically active metabolite of vitamin D, exerts its endocrinological influence via nuclear vitamin D receptor. It is being assessed as an emerging therapeutic strategy in models of various medical conditions, including acute brain injury. The purpose of the present study was to investigate the neuroprotective effects of calcitriol on GCI and further refine the potential underlying mechanisms. A total of 145 male rats were assigned to 5 groups as follows: Sham group, GCI group, calcitriol treatment group, PD98059 treatment group and vehicle-treated group. Brain water content and neurologic severity score were assessed to evaluate the brain edema and neurological deficits of rats. Histopathological changes and ultrastructures of cells were observed via hematoxylin and eosin stain and transmission electron microscopy, respectively. Immunofluorescent staining and western blot analysis were used to assess the expression of proteins and their co-localization at the molecular level. The results demonstrated that post-GCI administration of calcitriol attenuated brain edema and improved neurological function in rats. Calcitriol also caused marked extracellular signal-regulated kinase 1/2 pathway activation, and thereby attenuated neuronal apoptosis. The present study provided novel clues for understanding the mechanisms by which calcitriol exerts its neuroprotective activity in a rat model of GCI.

Shedding new light on female fertility: The role of vitamin D

In the last decades several studies suggested that vitamin D is involved in the modulation of the reproductive process in women due to the expression of VDR and 1α-hydroxylase in reproductive tissues such as ovary, uterus, placenta, pituitary and hypothalamus. Vitamin D has also a role in the regulation of sex hormone steroidogenesis. Increasing evidence suggests that vitamin D might have a regulatory role in polycystic ovary syndrome (PCOS)-associated symptoms, including ovulatory dysfunction, insulin resistance and hyperandrogenism. Vitamin D deficiency also has been reported to contribute to the pathogenesis of endometriosis due to its immunomodulatory and anti-inflammatory properties. Although most of the studies supported a role of vitamin D in the onset of these diseases, randomized controlled trials to assess the efficacy of vitamin D supplementation have never been performed. In this review we critically discuss the role of vitamin D in female fertility, starting from in vitro and in vivo studies, focusing our attention on the two most frequent causes of female infertility: PCOS and endometriosis.

Ovarian endometriosis and vitamin D serum levels

AIM

The aim of this study was to assess the vitamin D serum level in women with ovarian endometriosis; specifically, a possible correlation between the dimensions of ovarian endometriomas and vitamin D serum levels was evaluated.

MATERIALS AND METHODS

This was an observational study of childbearing-age women diagnosed with singleton ovarian endometrioma from January 2015 to December 2015. Women diagnosed with multiple ovarian endometriomas or extraovarian endometriosis were excluded.

RESULTS

Forty-nine women constituted the initial study cohort. In these women, the mean (±SD) 25-OH-D3 serum level was 22.0 (±8.9) ng/ml, and 42 of them (85.7%) were diagnosed with hypovitaminosis D. In the "hypovitaminosis D women", the mean (± SD) diameter of ovarian endometriomas was 40.2 ± 22.6 mm, while in the "normal vitamin D serum level women" it was 26.7 ± 12.1 mm (p = 0.1). However, a significant linear correlation between 25-OH-D3 serum level and the diameter of ovarian endometriomas was found (r = -0.3, p = 0.03).

CONCLUSION

We found a relatively high rate of women with ovarian endometriosis and hypovitaminosis D. Interestingly, a significant linear correlation between 25-OH-D3 serum levels and the diameter of ovarian endometrioma emerged.

Effects of Vitamin D on Endometriosis-Related Pain: A Double-Blind Clinical Trial

Background

Endometriosis is a disabling disease of reproductive-age women. Dysmenorrhea, dyspareunia, and pelvic pain are the main symptoms of endometriosis. Its etiology is not clear. Endometriosis may have various causes, including vitamin D deficiency, but its effect is controversial.

Material/Methods

In this double-blind clinical trial, we enrolled patients with endometriosis diagnosed and treated by laparoscopy, with scores of at least 3 for of dysmenorrhea and/or pelvic pain at 8 weeks after surgical treatment. They were randomly prescribed vitamin D (50 000 IU weekly for 12 weeks) or placebo. Severity of pain in the 2 groups (placebo and treatment) was compared by VAS test at 24 weeks after surgical treatment.

Results

There were 19 patients in the vitamin D group and 20 in the placebo group. Baseline characteristics in the 2 groups were similar. Following the treatment with vitamin D or placebo, we did not find significant differences in severity of pelvic pain (p=0.24) and dysmenorrhea (p=0.45) between the 2 groups. Mean pelvic pain at 24 weeks after laparoscopy in the vitamin D group was 0.84±1.74 and in placebo group it was 0.68±1.70 (p=0.513). Mean dysmenorrhea was 2.10±2.33 in the vitamin D group and 2.73±2.84 in the placebo group (p=0.45).

Conclusions

After ablative surgery for endometriosis, vitamin D treatment did not have a significant effect in reducing dysmenorrhea and/or pelvic pain.

Follicular fluid alterations in endometriosis: label-free proteomics by MS(E) as a functional tool for endometriosis

Endometriosis is a chronic gynecological condition that affects 10-32% of women of reproductive age and may lead to infertility. The study of protein profiles in follicular fluid may assist in elucidating possible biomarkers related to this disease. For this, follicular fluid samples were obtained from women with tubal factor or minimal male factor infertility who had pregnancy outcomes after in vitro fertilization (IVF) treatment (control group, n = 10), women with endometriosis (endometriosis group, n = 10), along with the endometrioma from these same patients were included (endometrioma group, n = 10). For proteomic analysis, samples were pooled according to their respective groups and normalized to protein content. Proteins were analyzed by in tandem mass spectrometry (MS(E)) Spectra processing and the ProteinLynx Global Server v.2.5. was used for database searching. Data was submitted to the biological network analysis using Cytoscape 2.8.2 with ClueGO plugin. As a result, 535 proteins were identified among all groups. The control group differentially or uniquely expressed 33 (6%) proteins and equal expression of 98 (18%) proteins was observed in the control and endometriosis groups of which 41 (7%) proteins were further identified and/or quantified. Six (1%) proteins were observed in both the endometriosis and endometrioma groups, but 212 (39%) proteins were exclusively identified and/or quantified in the endometrioma group. There were 9 (1%) proteins observed in both the control and endometrioma groups and there were 139 (25%) proteins common among all three groups. Distinct differences among the protein profiles in the follicular fluid of patients included in this study were found, identifying proteins related to the disease progression and IVF success. Thus, some pathways related to endometriosis are associated with the presence of specific proteins, as well as the absence of others. This study provides a first step to the development of more sensitive diagnostic tests and treatment.

Vitamin D and female fertility

PURPOSE OF REVIEW

Apart from the well known effects of vitamin D on maintaining calcium homeostasis and promoting bone mineralization, there is some evidence suggesting that vitamin D also modulates human reproductive processes. We will review the most interesting and relevant studies on vitamin D and female fertility published over the past year.

RECENT FINDINGS

In the past year, several observational studies reported a better in-vitro fertilization outcome in women with sufficient vitamin D levels (≥30 ng/ml), which was mainly attributed to vitamin D effects on the endometrium. One randomized controlled trial found an increased endometrial thickness in women with polycystic ovary syndrome (PCOS) receiving vitamin D during intrauterine insemination cycles. Further, vitamin D supplementation had a beneficial effect on serum lipids in PCOS women. Vitamin D treatment improved endometriosis in a rat model and increased vitamin D intake was related to a decreased risk of incident endometriosis. Vitamin D was also favorably associated with primary dysmenorrhea, uterine leiomyoma, and ovarian reserve in late reproductive aged women.

SUMMARY

In women undergoing in-vitro fertilization, a sufficient vitamin D level (≥30 ng/ml) should be obtained. Vitamin D supplementation might improve metabolic parameters in women with PCOS. A high vitamin D intake might be protective against endometriosis.