Are leptin and adiponectin involved in recurrent pregnancy loss?

Obesity and recurrent miscarriage: The interconnections between adipose tissue and the immune system

Currently, obesity is considered a global public health problem. It is the main risk factor for noncommunicable diseases and reproductive complications, such as recurrent miscarriage (RM). RM affects approximately 1% of couples of reproductive age, and recent studies suggest that its prevalence is increasing. Immunological abnormalities may be responsible for a significant number of cases of unexplained RM. Obesity is recognized as a chronic low-grade inflammatory condition. The accumulation of fat in obese adipose tissue promotes changes in the local and systemic immune response. Adipokines, exosomes, micro-RNAs, lipids, and other factors released or secreted by adipose tissue are responsible for the interconnection between obesity and the immune system. Obesity-induced dysregulation of the innate and acquired immune response is also involved in the immunopathology of pregnancy loss in patients with unexplained RM. Therefore, understanding the communication pathways between maternal adipose tissue and the immune response in women living with obesity and RM is an important objective. Thus, diagnostic tools and new immunomodulatory therapies may be proposed for the management of patients with concurrent obesity and RM.

Adiponectin/leptin and HOMA/adiponectin ratios in Iranian women with polycystic ovary syndrome

BACKGROUND

Insulin resistance and disrupted secretion of adipokines are the major contributors to the pathogenesis of polycystic ovary syndrome (PCOS). Previous research has indicated that adiponectin/leptin (A/L) and HOMA/adiponectin (H/A) ratios have a strong association with insulin resistance and metabolic syndrome. The current study aimed to assess the predictability of the A/L and H/A ratios for PCOS women infertility and recurrent pregnancy loss (RPL). In this study, we investigated the association of A/L and H/A ratios with PCOS, as well as infertility and RPL in Iranian women with PCOS.

METHODS

This case-control study included 150 PCOS (60 infertile and 90 PCOS-RPL) and 50 non-PCOS women. Clinical, biochemical, and hormonal features were evaluated, and the A/L and H/A ratios were calculated.

RESULTS

The A/L and H/A ratios were significantly decreased and increased in women with PCOS, respectively. A significant association was observed between the A/L and H/A ratios with PCOS, as well as PCOS-infertile and PCOS-RPL, even after adjusting for potential confounders. Although there was no significant difference between PCOS-infertile and PCOS-RPL subgroups, ROC curve analysis showed that A/L and H/A ratios could strongly predict PCOS with the area under the curve (AUC) of 0.867 and 0.861, respectively.

CONCLUSION

The ratios of A/L and H/A may serve as biomarkers to distinguish women with PCOS from non-PCOS in the Iranian population. However, it seems that they are not discriminatory markers for PCOS-associated RPL and infertility.

Plasma Complement C1q/tumor necrosis factor-related protein 15 concentration is associated with polycystic ovary syndrome

Polycystic ovarian syndrome (PCOS) is a common poignant endocrine disorder affecting women, posing a close association with metabolic syndrome and obesity. Existing literature characterizes PCOS with deranged levels of several adipokines and myokines. CTRP15 is a paralogue of adiponectin, mainly expressed by skeletal muscles, and plays a key role in insulin, glucose, and lipid metabolism. In the current study, we aim to determine the circulating levels of CTRP15 and evaluate its association with cardiometabolic and inflammatory parameters in PCOS women. This case-control study included 120 PCOS patients (60 Recurrent pregnancy loss (RPL) and 60 infertile (inf) PCOS) and 60 healthy non-PCOS controls. Serum levels of hs-CRP were measured by commercial kits, while serum levels of adiponectin and CTRP15 were determined using the ELISA technique. Serum levels of CTRP15 were significantly elevated in PCOS-RPL and PCOS-inf subgroups when compared to controls (94.80 ± 27.08 and 87.77 ± 25.48 vs. 54.78 ± 15.45, both P < 0.001). Moreover, serum adiponectin was considerably lower in the PCOS group and subgroups (P < 0.001), while serum hs-CRP, fasting insulin, HOMA-IR, and free testosterone were significantly higher when compared to the non-PCOS group (P < 0.05). Furthermore, CTRP15 closely associated with FSH, HOMA-IR, hs-CRP, and BMI. These results highlight a possible involvement of CTRP15 in the pathogenesis of PCOS. The elevated levels of CTRP15 might be a compensatory mechanism for the metabolic dysregulations (excess adiposity, insulin resistance, metaflammation) associated with the syndrome. Nevertheless, future studies are necessary to unravel the underlying mechanism.

Early-pregnancy prediction of risk for pre-eclampsia using maternal blood leptin/ceramide ratio: discovery and confirmation

OBJECTIVE

This study aimed to develop a blood test for the prediction of pre-eclampsia (PE) early in gestation. We hypothesised that the longitudinal measurements of circulating adipokines and sphingolipids in maternal serum over the course of pregnancy could identify novel prognostic biomarkers that are predictive of impending event of PE early in gestation.

STUDY DESIGN

Retrospective discovery and longitudinal confirmation.

SETTING

Maternity units from two US hospitals.

PARTICIPANTS

Six previously published studies of placental tissue (78 PE and 95 non-PE) were compiled for genomic discovery, maternal sera from 15 women (7 non-PE and 8 PE) enrolled at ProMedDx were used for sphingolipidomic discovery, and maternal sera from 40 women (20 non-PE and 20 PE) enrolled at Stanford University were used for longitudinal observation.

OUTCOME MEASURES

Biomarker candidates from discovery were longitudinally confirmed and compared in parallel to the ratio of placental growth factor (PlGF) and soluble fms-like tyrosine kinase (sFlt-1) using the same cohort. The datasets were generated by enzyme-linked immunosorbent and liquid chromatography-tandem mass spectrometric assays.

RESULTS

Our discovery integrating genomic and sphingolipidomic analysis identified leptin (Lep) and ceramide (Cer) (d18:1/25:0) as novel biomarkers for early gestational assessment of PE. Our longitudinal observation revealed a marked elevation of Lep/Cer (d18:1/25:0) ratio in maternal serum at a median of 23 weeks' gestation among women with impending PE as compared with women with uncomplicated pregnancy. The Lep/Cer (d18:1/25:0) ratio significantly outperformed the established sFlt-1/PlGF ratio in predicting impending event of PE with superior sensitivity (85% vs 20%) and area under curve (0.92 vs 0.52) from 5 to 25 weeks of gestation.

CONCLUSIONS

Our study demonstrated the longitudinal measurement of maternal Lep/Cer (d18:1/25:0) ratio allows the non-invasive assessment of PE to identify pregnancy at high risk in early gestation, outperforming the established sFlt-1/PlGF ratio test.

Follicular microenvironment: Oxidative stress and adiponectin correlated with steroids hormones in women undergoing in vitro fertilization

Research has been focused on determining the follicular microenviroment produced by the theca and granulosa cells since the molecular characterisation of this body fluid could lead to the understanding of several fertility problems. Oxidative stress may be one of the factors involved in female infertility since it plays a key role in the modulation of oocyte maturation and finally pregnancy. An increase in oxidative stress is correlated with inflammation and intense research was developed to understand the interaction between inflammation and adiponectin, based on the fact that many adipokines are inflammation related proteins linked to reactive oxygen species production. The aim of this study is to investigate the correlation between total adiponectin levels and oxidative stress amount in the serum and follicular fluid (FF) of women who undergone in vitro fertilization. Moreover we verified the expression of adiponectin in granulosa and cumulus cells. To clarify the predictive value of steroid hormones in human assisted reproduction, twelve steroid hormones in FF and serum, were quantified in a single run liquid chromatography/mass spectrometry, by using a multiple reaction monitoring mode and we related the serum and follicular fluids adiponectin levels with the concentration of the investigated steroid hormones.

Contribution of ADIPOQ Variants to the Genetic Susceptibility of Recurrent Pregnancy Loss

Adiponectin is a hormone implicated in regulating energy, lipid, and glucose metabolism and is encoded by the ADIPOQ gene. ADIPOQ variants can regulate the circulating levels of adiponectin. Irregular adiponectin concentrations have been associated with numerous reproductive diseases including recurrent pregnancy loss (RPL). The main objective of this study was to determine whether the 14 selected polymorphisms of the ADIPOQ gene are linked with RPL. The retrospective case-control study comprised a total of 332 women with RPL, adjusted as more than three consecutive abortions of unknown etiology, and 286 healthy controls. They were genotyped for the ADIPOQ variants using allele exclusion method on real-time PCR. Significantly higher rs1501299 minor allele frequencies (MAF) and lower rs2241767 and rs2241766 MAF were seen among RPL women, thereby assigning disease susceptibility and protective aspect to the mentioned variants, respectively. Different associations of ADIPOQ genotypes with RPL were noticed according to the genetic model exploited: rs1501299 and rs2241767 were significantly linked with RPL under the three models, while rs17366568 and rs2241766 were associated with RPL under codominant and dominant models, and rs7649121 was related to RPL under the dominant and recessive models. rs4632532 was linked according to the recessive model only. Based on LD pattern, 2-haplotype blocks were specified. Reduced frequency of AGG and GAGG and increased frequency of TAAG were noted in cases, compared with controls, hence indicating these haplotypes as RPL-protective and RPL-susceptible, respectively. These results support a significant role of ADIPOQ as an RPL candidate locus.

Adiponectin Reduces Embryonic Loss Rate and Ameliorates Trophoblast Apoptosis in Early Pregnancy of Mice with Polycystic Ovary Syndrome by Affecting the AMPK/PI3K/Akt/FoxO3a Signaling Pathway

Reports in recent years have suggested that adiponectin (APN) improves insulin resistance and inhibits apoptosis by activating the AMP-activated protein kinase (AMPK) pathway and the PI3K/Akt signaling pathway after binding to its receptor. This study aims to explore the mechanism by which APN reduces embryo loss rate and trophoblast apoptosis in early pregnancy of mice with polycystic ovary syndrome (PCOS). PCOS mice were subcutaneously injected with APN (10 μg mg kg^-1 day^-1) on 11 consecutive days from the 3rd day of pregnancy onwards to observe the change of the embryo loss rate of PCOS mice induced by APN. Quantitative real-time PCR and Western blot were used to determine the relative expressions of mRNA and the proteins AMPK, PI3K, and Akt in mouse uterine tissue. At the same time, primary cultured mouse villous trophoblast cells were used to further explore the underlying mechanisms in vitro. APN significantly reduces the pregnancy loss rate of PCOS mice. At the same time, APN increases phosphorylation and mRNA expression levels of AMPK, PI3K, and Akt in PCOS mouse uterine tissue. In addition, trophoblast cells of model mice were treated with APN and inhibitors, and APN was found to reduce trophoblast cell apoptosis by affecting the phosphorylation levels of AMPK, PI3K, Akt, and FoxO3a proteins. APN reduces the embryo loss rate and ameliorates trophoblast apoptosis in PCOS mice by affecting the AMPK/PI3K/AKT/FoxO3a signaling pathway.

Circulating levels of Meteorin-like protein in polycystic ovary syndrome: A case-control study

Patients diagnosed with polycystic ovary syndrome (PCOS) are at high risk of developing a myriad of endocrinologic and metabolic derailments. Moreover, PCOS is a leading cause of habitual abortion, also known as recurrent pregnancy loss (RPL). Meteorin-like protein (Metrnl) is a newly discovered adipokine with the potential to counteract the metaflammation. This study aimed at determining the associations of serum Metrnl levels with homocysteine, hs-CRP, and some components of metabolic syndrome in PCOS-RPL and infertile PCOS patients.This case-control study was conducted in 120 PCOS patients (60 PCOS-RPL and 60 infertile) and 60 control. Serum hs-CRP and homocysteine were assessed using commercial kits, while adiponectin, Metrnl, FSH, LH, free testosterone and insulin levels were analyzed using ELISA technique. Serum Metrnl levels were found to be lower in PCOS patients when compared to controls (67.98 ± 26.66 vs. 96.47 ± 28.72 pg/mL, P <0.001)). Furthermore, serum adiponectin levels were lower, while free testosterone, fasting insulin, HOMA-IR, homocysteine, and hs-CRP were significantly higher in PCOS group compared to controls. Moreover, serum Metrnl correlated with BMI, adiponectin, and homocysteine in controls, and inversely correlated with FBG, fasting insulin, and HOMA-IR in PCOS group and subgroups. Besides, it inversely correlated with hs-CRP in control, and PCOS group and subgroups. These findings revealed a possible role of Metrnl in the pathogenesis of PCOS and RPL. Nevertheless, there is a necessity for future studies to prove this concept.

Circulating levels of C1q/TNF-α-related protein 6 (CTRP6) in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders affecting females of reproductive age. It has been associated with cardiometabolic disorders including diabetes mellitus and cardiovascular disorders, and increases the risk of developing fecundity pathologies including recurrent pregnancy loss (RPL) and infertility. C1q/tumor necrosis factor-α-related protein-6 (CTRP6) is a novel adipokine involved in glucose and lipid metabolism, host inflammation, and organogenesis. In the present study, we aimed to determine the association of serum CTRP6 levels with some components of metabolic syndrome in PCOS patients (infertile PCOS [inf-PCOS] and PCOS-RPL). This case-control study included 120 PCOS patients (60 inf-PCOS and 60 PCOS-RPL) and 60 healthy controls. Serum high-sensitivity C-reactive protein (hs-CRP) and homocysteine were measured using commercial kits, while adiponectin and CTRP6 levels were assessed using ELISA technique. Inf-PCOS and PCOS-RPL individuals had higher levels of serum CTRP6 than controls (546.15 ± 125.02 ng/ml and 534.04 ± 144.19 ng/ml vs. 440.16 ± 159.24 ng/ml; both p < .001). Moreover, serum adiponectin levels were significantly reduced, while fasting insulin, homeostasis model assessment of insulin resistance, free testosterone, and hs-CRP levels were significantly elevated in PCOS group, when compared with controls. Furthermore, serum CTRP6 positively associated with body mass index in all subjects. It showed an inverse correlation with adiponectin in PCOS group and subgroups. However, it had a direct association with hs-CRP in PCOS group and inf-PCOS subgroup, but not PCOS-RPL subgroup. These findings unravel a probable role of CTRP6 in PCOS pathogenesis, which poses a possibility to be a good diagnostic target. However, further investigation is needed.