Polycystic ovary syndrome is associated with increased osteopontin levels

Osteopontin - A potential biomarker of advanced liver disease

Cirrhosis is a primary cause of liver-related mortality and morbidity. The basic process driving chronic liver disease to cirrhosis is accelerated fibrogenesis. Although the pathogenesis of liver cirrhosis is a multifactorial process, the essential step in the evolution of liver fibrosis is the activation of hepatic stellate cells, which are the main source of collagen produced in the extracellular matrix. This activation process is mediated by multiple growth factors, cytokines, and chemokines. One of the hepatic stellate cell-activating signaling molecules (and also one associated with cell injury and fibrosis) is osteopontin (OPN). OPN concentration in the plasma has been found to be predictive of liver fibrosis in various liver diseases. OPN concentrations correlate significantly with the stage of fibrosis, liver insufficiency, portal hypertension, and the presence of hepatocellular cancer. However, due to its versatile signaling functions, OPN not only contributes to the development of liver cirrhosis, but is also implicated in the pathogenesis of other chronic hepatic diseases such as viral hepatitis, both alcoholic and non-alcoholic steatohepatitis, drug-induced liver injury, and hepatocellular cancer. Thus, the targeting of OPN pathways seems to be a promising approach in the treatment of chronic liver diseases.

Plasma and follicular fluid osteopontin levels during ovarian cycle and their correlation with follicular fluid vascular endothelial growth factor levels

Osteopontin (OPN) is a multifunctional secreted glycoprotein. We evaluated OPN concentrations in blood and follicular fluid (FF) during the ovarian cycle and their relationship with the production of vascular endothelial growth factor (VEGF), which is involved in the pathophysiology of ovarian hyperstimulation syndrome (OHSS). Twenty-two women undergoing in vitro fertilization (minimal stimulation protocol with clomiphene citrate) were enrolled. Samples were collected (a) on the third day of withdrawal bleeding, (b) 2 days before oocyte retrieval, and (c) on the day of oocyte retrieval. FF was collected during oocyte retrieval. The OPN concentration in each specimen and the VEGF concentration in FF was measured by enzyme-linked immunosorbent assays. Plasma OPN concentrations were (in ng/mL): (a) 416 ± 37.2, (b) 378 ± 35.8, and (c) 390 ± 40.0, with no significant differences between the groups. The OPN concentration in FF was 106 ± 13.4 ng/mL. A positive correlation was found between OPN concentrations in FF and plasma samples. A positive correlation was also found between plasma OPN and FF VEGF concentrations, irrespective of the blood-sampling period. Plasma OPN concentration is suggested to reflect the FF VEGF level at oocyte retrieval and maybe a novel clinical marker for predicting the risk for OHSS.

Differential regulation of osteopontin and CD44 correlates with infertility status in PCOS patients

Endometrial receptivity is mediated by adhesion molecules at the endometrium-trophoblast interface where osteopontin (OPN) and CD44 form a protein complex that plays an important role in embryo recognition. Here, we undertook a prospective study investigating the expression and regulation of OPN and CD44 in 50 fertile and 31 infertile ovulatory polycystic ovarian syndrome (PCOS) patients in the proliferative and secretory phases of the natural menstrual cycle and in 12 infertile anovulatory PCOS patients. Endometrial biopsies and blood samples were evaluated for expression of OPN and CD44 using RT-PCR, immunohistochemistry and ELISA analysis to determine circulating levels of OPN, CD44, TNF-α, IFN-γ and OPN and CD44 levels in biopsy media. Our findings highlighted an increased level of circulating OPN and CD44 in serum from infertile patients that inversely correlated with expression levels in endometrial tissue and positively correlated with levels secreted into biopsy media. OPN and CD44 levels positively correlated to each other in serum and media from fertile and PCOS patients, as well as to circulating TNF-α and IFN-γ. In vitro analysis revealed that hormone treatment induced recruitment of ERα to the OPN and CD44 promoters with a concomitant increase in the expression of these genes. In infertile patients, inflammatory cytokines led to recruitment of NF-κB and STAT1 proteins to the OPN and CD44 promoters, resulting in their overexpression. These observations suggest that the endometrial epithelial OPN-CD44 adhesion complex is deficient in ovulatory PCOS patients and displays an altered stoichiometry in anovulatory patients, which in both cases may perturb apposition. This, together with elevated circulating and local secreted levels of these proteins, may hinder endometrium-trophoblast interactions by saturating OPN and CD44 receptors on the surface of the blastocyst, thereby contributing to the infertility associated with ovulating PCOS patients. KEY MESSAGES: • Endometrial epithelial OPN-CD44 adhesion complex levels are deficient in ovulatory PCOS patients contributing to the endometrial infertility associated with ovulating PCOS patients. • Circulating levels of OPN, CD44 and inflammatory cytokines TNF-α and IFN-γ are altered in infertile PCOS patients. • Increased levels of both OPN and CD44 in biopsy media and serum inversely correlate with endometrial expression of these markers in endometrial tissue. • In infertile PCOS patients, high levels of oestrogens and inflammatory cytokines stimulate the recruitment of transcription factors to the OPN and CD44 promoters to enhance gene transcription. • Our study identifies a novel crosstalk between the CD44-OPN adhesion complex, ERα, STAT1 and NF-κB pathways modulating endometrial receptivity.

Fibroblast growth factor 23 and 25(OH)D levels are related to abdominal obesity and cardiovascular risk in patients with polycystic ovarian syndrome

Fibroblast growth factor 23 (FGF23) and Klotho are extensively studied in relation to bone metabolism and progression of chronic kidney disease. There is very limited information about their role in polycystic ovarian syndrome (PCOS). The aim of the present study was to investigate some bone markers in women with PCOS in relation to obesity and cardiovascular risk. In the study were included 80 patients, divided into three age-matched groups -Non-obese PCOS (n = 40); Obese PCOS (n = 20) and Obese control group (n = 20). Bone marker levels were measured by an enzyme-linked immunosorbent assay. Obese PCOS patients had higher levels of FGF23 and sRANKL, lower levels of 25(OH)D and higher prevalence of vitamin D deficiency compared to non-obese subjects. Patients with abdominal obesity (waist circumference >80 cm) independently of PCOS status had significantly higher levels of FGF23 (112.5 ± 86.5 vs. 73.4 ± 37.9 pg/ml; p = .023) and lower of 25(OH)D (35.8 ± 21.4 vs 47.8 ± 26.5 nmol/l; p = .034). Patients with PCOS at risk of cardiovascular diseases according to AE-PCOS consensus also had increased levels of FGF23 (111.6 ± 84.5 vs. 66.5 ± 35.1 pg/ml; p = .031) and decreased levels of 25(OH)D (31.9 ± 16.8 vs. 47.1 vs 28.4 nmol/l; p = .017) compared to those not at risk. There was no correlation between bone markers and blood glucose levels, insulin resistance or hormonal levels.

Understanding the association of polycystic ovary syndrome and non-alcoholic fatty liver disease

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder among reproductive-age women. Patients with non-alcoholic fatty liver disease (NAFLD) often suffer from metabolic syndrome, atherosclerosis, ischemic heart disease, and extrahepatic tumors, conferring a lower survival than the general population; therefore it is crucial to study the association between NAFLD and PCOS since it remains poorly understood. Insulin resistance (IR) plays a central role in the pathogenesis of NAFLD and PCOS; also, hyperandrogenism enhances IR in these patients. IR, present in the NAFLD-PCOS association could decrease the hepatic production of sex hormone-binding globulin through a possible regulation mediated by hepatocyte nuclear factor 4 alpha. On the other hand, apoptotic processes initiated by androgens actively contribute to the progression of NAFLD. Considering the association between the two conditions, the screening of women with PCOS for the presence of NAFLD appears reasonable. The pathophysiological mechanisms of PCOS-NAFLD association and the initial approach will be reviewed here.

Serum osteopontin negatively impacts on intima-media thickness in patients with systemic lupus erythematosus

BACKGROUND

Ultrasound evaluation of carotid intima-media thickness (cIMT) has been extensively used for potentially improving cardiovascular (CV) risk stratification in several patients' categories. Subjects with systemic lupus erythematosus (SLE) have been investigated by both imaging and molecular biomarker approaches with contrasting results. Here, we focused on the role of osteopontin (OPN) as biomarker of subclinical atherosclerosis associated with SLE.

MATERIALS AND METHODS

Eighty females (age 18-65 years) affected by SLE and eighty age-matched healthy female controls without a clinical history of CV disease underwent ultrasound evaluation of cIMT and blood sample assay of high-sensitivity C-reactive protein (hs-CRP) and OPN.

RESULTS

Healthy controls and SLE patients significantly differed for CV risk factors (ie, waist circumference, hypertension and dyslipidaemia) and the inflammatory status. Noteworthy, an opposite association between cIMT and OPN was observed in the two study groups. Whereas OPN was positively associated with mean cIMT (r = 0.364; P = 0.001) in SLE patients, a negative correlation was found in healthy controls. Furthermore, in SLE patients increased circulating levels of OPN were associated with the use of hydroxychloroquine and the positivity for the anti-dsDNA autoantibodies. At linear regression analysis, only OPN remained independently associated with cIMT also after adjustment for age, smoking pack-year, Heart SCORE, disease length and steroid therapy length.

CONCLUSIONS

These results indicate that serum OPN levels were strongly associated with subclinical atherosclerosis in patients with LES and it might be a useful CV biomarker that requires additional validation in larger trials.

Circulating osteopontin and its association with liver fat content in non-obese women with polycystic ovary syndrome: a case control study

BACKGROUND

Osteopontin (OPN) plays an important role in inflammatory processes and insulin resistance. Polycystic ovary syndrome (PCOS) is a reproductive metabolic disease associated with insulin resistance and metabolic abnormalities, including high levels of liver fat content (LFC). The objective of this study was to explore whether circulating OPN independently contributes to elevated LFC in non-obese PCOS patients.

METHODS

This study included 61 non-obese PCOS patients and 56 age-matched healthy women from Shanghai, China. After an overnight fast, all participants underwent anthropometric measurements, oral glucose tolerance tests, lipid profile and sex hormone measurements. Quantitative measurement of LFC by ultrasonography was performed. OPN concentrations were measured using ELISA. An independent samples t-test and the Mann-Whitney U test were performed to compare variables between the two groups; one-way ANOVA and Kruskal-Wallis test were performed to compare four subgroups of patients. Correlations were determined by Spearman's correlation tests. Stepwise multiple linear regression analyses were performed to assess for independent contributors. A receiver operating characteristic curve with the maximum Youden index was calculated for the optimal cut-off value.

RESULTS

In non-obese PCOS women, circulating OPN levels were increased in the subgroups with a higher body mass index (BMI) and free androgen index (FAI), and the LFC levels were increased in the elevated OPN subgroups. Moreover, increased OPN was associated with increased FAI and LFC in PCOS women, and the association between OPN and LFC was independent of triglyceride, HOMA-IR and FAI after adjusting for PCOS status in all participants. OPN combined with FAI and hsCRP may better predict NAFLD than WHR in this study cohort. However, there was no significant difference in circulating OPN levels between non-obese PCOS and normal control women.

CONCLUSIONS

Increased OPN levels may be related to FAI and elevated LFC in non-obese women with PCOS.