Biomarkers in Polycystic Ovary Syndrome

Polycystic Ovary Syndrome (PCOS) is the most common endocrine disorder in reproductive-age women. PCOS is diagnosed by the presence of two of the following three characteristics: hyperandrogenemia and/or hyperandrogenism, oligo/amenorrhea, and polycystic ovarian morphology. PCOS is associated with reproductive and non-reproductive complications, including obesity, insulin resistance and diabetes, dyslipidemia, and increased blood pressure. There is an urgent need for biomarkers that address both the reproductive and non-reproductive aspects of this complex syndrome. This review focuses on biomarkers, or potential ones, associated with the reproductive and non-reproductive aspects of PCOS, including anthropometric and clinical biomarkers, insulin and the IGF-1 system, lipids, anti-Müllerian hormone and gonadotropins, steroids, inflammatory and renal injury biomarkers, oxidative stress, and non-coding RNAs. We expect that this review will bring some light on the recent updates in the field and encourage researchers to join the exciting and promising field of PCOS biomarkers.

Loss of microRNA-21 protects against acetaminophen-induced hepatotoxicity in mice

Acetaminophen (APAP)-induced Acute Liver Failure (ALF) is recognized as the most common cause of ALF in Western societies. APAP-induced ALF is characterized by coagulopathy, hepatic encephalopathy, multi-organ failure, and death. MicroRNAs are small, non-coding RNAs that regulate gene expression at the post-transcriptional level. MicroRNA-21 (miR-21) is dynamically expressed in the liver and is involved in the pathophysiology of both acute and chronic liver injury models. We hypothesize that miR-21genetic ablation attenuates hepatotoxicity following acetaminophen intoxication. Eight-week old miR-21knockout (miR21KO) or wild-type (WT) C57BL/6N male mice were injected with acetaminophen (APAP, 300 mg/kg BW) or saline. Mice were sacrificed 6 or 24 h post-injection. MiR21KO mice presented attenuation of liver enzymes ALT, AST, LDH compared with WT mice 24 h post-APAP treatment. Moreover, miR21KO mice had decreased hepatic DNA fragmentation and necrosis than WT mice after 24 h of APAP treatment. APAP-treated miR21KO mice showed increased levels of cell cycle regulators CYCLIN D1 and PCNA, increased autophagy markers expression (Map1LC3a, Sqstm1) and protein (LC3AB II/I, p62), and an attenuation of the APAP-induced hypofibrinolytic state via (PAI-1) compared with WT mice 24 post-APAP treatment. MiR-21 inhibition could be a novel therapeutic approach to mitigate APAP-induced hepatotoxicity and enhance survival during the regenerative phase, particularly to alter regeneration, autophagy, and fibrinolysis. Specifically, miR-21 inhibition could be particularly useful when APAP intoxication is detected at its late stages and the only available therapy is minimally effective.

RF10 | PMON249 MicroRNA-21 Ablation Exacerbates Androgen-Mediated White Adipose Tissue Dysfunction and Impaired Insulin Signaling in a Mouse Model of Polycystic Ovary Syndrome

Background

Polycystic ovary syndrome (PCOS) is characterized by oligo- or anovulation, polycystic ovaries, and hyperandrogenism. PCOS is associated with white adipose tissue (WAT) expansion and dysfunction, which has been linked to impaired insulin signaling in a number of metabolic diseases. MicroRNAs dysregulation in WAT is involved in the development of obesity and its associated complications. MicroRNA-21 (miR-21), the most abundant circulatory microRNA in women with PCOS, regulates androgen receptor (AR) expression in prostate cancer however, its role in WAT dysfunction in PCOS, and the associated systemic insulin resistance, is unknown. Using a well-established PCOS model of hyperandrogenemia we aim to test the hypothesis that miR-21 regulates AR expression to modulate androgen-mediated WAT dysfunction and the associated local and systemic insulin resistance.

Methods

Three-week-old miR-21 knockout (miR-21KO) or wild type (WT) female mice were treated with dihydrotestosterone (DHT, 8 mg/Silastic tube) or vehicle for 90 days (n=6/group). Body composition (EchoMRI) and oral glucose tolerance test (OGTT) were assessed. HOMA-IR index was calculated from fasting serum glucose and insulin levels. Retroperitoneal fat (RPF), a WAT depot that is linked to poor plasma glycemic indices and systemic inflammation, was collected to assess adipocyte size and perform molecular determinations. RPF miR-21 levels, as well as gene and protein expression of AR, and insulin signaling markers (IRS-1/2, insulin receptor-β, PI3K, AKT, Glut4, GSK-α, PTEN) were quantified by RT-qPCR and Western blot.

Results

In WT mice, DHT increased body weight (25.07 ± 0.52 vs 21.79 ± 0.47 g, p<0.05), fat mass (4.60 ± 0.46 vs 1.98 ± 0.12 g, p<0.05), RPF mass (29.68 ± 3.39 vs. 172.64 ± 32.75 g, p<0.05), RPF miR-21 (2.5-fold) and AR expression (2.1-fold). Adipocyte size analysis revealed a hypertrophic response to DHT, which was associated with impaired OGTT (186.10 ± 5.99 vs 250.70 ± 14.76 mg. min/dL, p<0.05) and downregulation of IRS-1/2, insulin receptor-β, and AKT, indicating impaired insulin signaling. MiR-21 ablation had no effect on DHT-mediated total fat or RPF mass increases, but it exacerbated DHT-mediated AR upregulation, RPF hypertrophy, and insulin resistance as measured by the HOMA-IR index. DHT-mediated reduction in GSK-α, which mediates obesity-induced inflammation, was abolished in miR-21KO mice. Glut4 protein was only downregulated in miR-21KO DHT-treated mice, despite DHT downregulating Glut4 mRNA in both strains. Furthermore, DHT only upregulated PTEN, a negative insulin signaling regulator and known target of miR-21 in miR-21KO mice.

Conclusion

and significance: These findings imply that WAT miR-21 plays a protective role in PCOS by alleviating androgen-mediated adipose tissue structural and molecular derangements, as well as the associated local and systemic insulin resistance via downregulating AR. Modulation of miR-21 levels in adipose tissue could be a novel therapeutic approach for the treatment of PCOS-related metabolic derangements.

Presentation: Saturday, June 11, 2022 1:00 p.m. - 1:05 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Mitochondrial function and oxidative stress in white adipose tissue in a rat model of PCOS: effect of SGLT2 inhibition

Background

Polycystic ovary syndrome (PCOS), characterized by androgen excess and ovulatory dysfunction, is associated with a high prevalence of obesity and insulin resistance (IR) in women. We demonstrated that sodium–glucose cotransporter-2 inhibitor (SGLT2i) administration decreases fat mass without affecting IR in the PCOS model. In male models of IR, administration of SGLT2i decreases oxidative stress and improves mitochondrial function in white adipose tissue (WAT). Therefore, we hypothesized that SGLT2i reduces adiposity via improvement in mitochondrial function and oxidative stress in WAT in PCOS model.

Methods

Four-week-old female rats were treated with dihydrotestosterone for 90 days (PCOS model), and SGLT2i (empagliflozin) was co-administered during the last 3 weeks. Body composition was measured before and after SGLT2i treatment by EchoMRI. Subcutaneous (SAT) and visceral (VAT) WAT were collected for histological and molecular studies at the end of the study.

Results

PCOS model had an increase in food intake, body weight, body mass index, and fat mass/lean mass ratio compared to the control group. SGLT2i lowered fat mass/lean ratio in PCOS. Glucosuria was observed in both groups, but had a larger magnitude in controls. The net glucose balance was similar in both SGLT2i-treated groups. The PCOS SAT had a higher frequency of small adipocytes and a lower frequency of large adipocytes. In SAT of controls, SGLT2i increased frequencies of small and medium adipocytes while decreasing the frequency of large adipocytes, and this effect was blunted in PCOS. In VAT, PCOS had a lower frequency of small adipocytes while SGLT2i increased the frequency of small adipocytes in PCOS. PCOS model had decreased mitochondrial content in SAT and VAT without impacting oxidative stress in WAT or the circulation. SGLT2i did not modify mitochondrial function or oxidative stress in WAT in both treated groups.

Conclusions

Hyperandrogenemia in PCOS causes expansion of WAT, which is associated with decreases in mitochondrial content and function in SAT and VAT. SGLT2i increases the frequency of small adipocytes in VAT only without affecting mitochondrial dysfunction, oxidative stress, or IR in the PCOS model. SGLT2i decreases adiposity independently of adipose mitochondrial and oxidative stress mechanisms in the PCOS model.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-022-00455-x.

Androgen excess in PCOS model is associated with decreased markers of mitochondrial content in both subcutaneous and visceral white adipose tissue.

Androgen excess in PCOS model is associated with increased frequency of small adipocytes in subcutaneous white adipose tissue while decreasing frequency of small adipocytes in visceral white adipose tissue.

SGLT2 inhibition did not modify markers of mitochondrial content or oxidative stress in either subcutaneous or visceral white adipose tissue in PCOS model.

SGLT2 inhibition increased frequency of small adipocytes in both subcutaneous and visceral white adipose tissue in control rats; however, SGLT2 inhibition only increased frequency of small adipocytes in visceral white adipose tissue in PCOS model.

Cellular and behavioral effects of altered NaV1.2 sodium channel ion permeability in Scn2aK1422E mice

Genetic variants in SCN2A, encoding the Na_V1.2 voltage-gated sodium channel, are associated with a range of neurodevelopmental disorders with overlapping phenotypes. Some variants fit into a framework wherein gain-of-function missense variants that increase neuronal excitability lead to developmental and epileptic encephalopathy, while loss-of-function variants that reduce neuronal excitability lead to intellectual disability and/or autism spectrum disorder (ASD) with or without co-morbid seizures. One unique case less easily classified using this framework is the de novo missense variant SCN2A-p.K1422E, associated with infant-onset developmental delay, infantile spasms and features of ASD. Prior structure–function studies demonstrated that K1422E substitution alters ion selectivity of Na_V1.2, conferring Ca²⁺ permeability, lowering overall conductance and conferring resistance to tetrodotoxin (TTX). Based on heterologous expression of K1422E, we developed a compartmental neuron model incorporating variant channels that predicted reductions in peak action potential (AP) speed. We generated Scn2a^K1422E mice and characterized effects on neurons and neurological/neurobehavioral phenotypes. Cultured cortical neurons from heterozygous Scn2a^K1422E/+ mice exhibited lower current density with a TTX-resistant component and reversal potential consistent with mixed ion permeation. Recordings from Scn2a^K1442E/+ cortical slices demonstrated impaired AP initiation and larger Ca²⁺ transients at the axon initial segment during the rising phase of the AP, suggesting complex effects on channel function. Scn2a^K1422E/+ mice exhibited rare spontaneous seizures, interictal electroencephalogram abnormalities, altered induced seizure thresholds, reduced anxiety-like behavior and alterations in olfactory-guided social behavior. Overall, Scn2a^K1422E/+ mice present with phenotypes similar yet distinct from other Scn2a models, consistent with complex effects of K1422E on Na_V1.2 channel function.

Cardiac and Renal SARS-CoV-2 Viral Entry Protein Regulation by Androgens and Diet: Implications for Polycystic Ovary Syndrome and COVID-19

The susceptibility and the severity of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are associated with hyperandrogenism, obesity, and preexisting pulmonary, metabolic, renal, and cardiac conditions. Polycystic ovary syndrome (PCOS), the most common endocrine disorder in premenopausal women, is associated with obesity, hyperandrogenism, and cardiometabolic dysregulations. We analyzed cardiac, renal, circulatory, and urinary SARS-CoV-2 viral entry proteins (ACE2, TMPRSS2, TMPRSS4, furin, cathepsin L, and ADAM17) and androgen receptor (AR) expression, in a peripubertal androgen exposure model of PCOS. Peripubertal female mice were treated with dihydrotestosterone (DHT) and low (LFD) or high (HFD) fat diet for 90 days. HFD exacerbated DHT-induced increase in body weight, fat mass, and cardiac and renal hypertrophy. In the heart, DHT upregulated AR protein in both LFD and HFD, ACE2 in HFD, and ADAM17 in LFD. In the kidney, AR protein expression was upregulated by both DHT and HFD. Moreover, ACE2 and ADAM17 were upregulated by DHT in both diets. Renal TMPRSS2, furin, and cathepsin L were upregulated by DHT and differentially modulated by the diet. DHT upregulated urinary ACE2 in both diets, while neither treatment modified serum ACE2. Renal AR mRNA expression positively correlated with Ace2, Tmprss2, furin, cathepsin L, and ADAM17. Our findings suggest that women with PCOS could be a population with a high risk of COVID-19-associated cardiac and renal complications. Furthermore, our study suggests that weight loss by lifestyle modifications (i.e., diet) could potentially mitigate COVID-19-associated deleterious cardiorenal outcomes in women with PCOS.

Hepatic Dysregulation of Bile Acid Homeostasis in Hyperandrogenemic Female Mouse Model of Polycystic Ovary Syndrome

Introduction and Purpose: Polycystic Ovary Syndrome (PCOS) is recognized as the most common endocrine disorder in women of reproductive age. Notably, PCOS women with hyperandrogenism have a pronounced increased risk for cardio-metabolic comorbidities compared with healthy individuals. Bile acids are endocrine signaling molecules that modulate hepatic lipid, glucose, and energy metabolism by aiding in absorption of lipids. Alteration of bile acid homeostasis affects overall metabolic homeostasis and contributes to pathogenesis of an array of metabolic diseases, although the molecular mechanisms of this have not been studied in PCOS. Methods: Four-week old C57BL/6N female mice were implanted subcutaneously with dihydrotestosterone (DHT, 8.0 mg) or vehicle silastic tubes (n=8/grp). Weekly body weight, food intake, and body composition was assessed. Fasting serum was obtained and the oral glucose tolerance test (OGTT) was performed in the last week of treatment. Animals were euthanized on treatment day 90 and livers were harvested. Expression levels of mRNA were assessed using RT-qPCR. Results: DHT treated females had significantly higher liver mass (1,387 ± 51 vs 1,197 ± 29 g, p<0.05), increased lean mass (21.25 ± 0.27 vs 19.58 ± 0.23 g, p<0.05) and increased fat mass (4.83 ± 0.47 vs 3.59 ± 0.36 g, p<0.05) compared to the vehicle counterparts. These hyperandrogenemic females additionally showed altered glucose homeostasis, having increased fasting glucose (201.10 ± 11.11 vs 152.80 ± 9.23 mg/dL, p<0.05) and an increased area under the curve (209.2± 11.0 vs 160.8± 3.5 mg.min/dL, p<0.05) following OGTT. Hepatic expression of both classic (Cyp8b1, 1.4 ± 0.1-fold, p<0.05) and alternative (Cyp7b1, 2.0 ± 0.3-fold, p<0.05) bile acid synthesis cytochrome P450 enzyme genes were significantly upregulated in DHT treated animals. Additionally, expression of sulfotransferase Sult2a2 was completely abolished in DHT treated animals compared with vehicle animals, indicating the possibility of androgen regulation of the sulfonation of bile acids marked for elimination. Liver expression of both the bile acid receptor G-protein coupled bile acid receptor 1 and the androgen receptor were both significantly downregulated (Gpbar1: 0.68 ± 0.08-fold, AR: 0.46 ± 0.04-fold, p<0.05) in DHT treated animals. Conclusions: Bile acid synthesis, transport, and elimination are tightly controlled processes in the liver to maintain a constant bile acid pool and limit reabsorption. Together, our results highlight the potential role of androgens in DHT-treated female mice in the dysregulation of bile acid homeostasis and its potential contribution to influence metabolic dysfunction. (Supported by NIH grants NIGMS P20GM-121334 to LLYC and DGR, and NIH NIDDK R21DK-113500 to DGR and the Mississippi Center of Excellence in Perinatal Research.)

MicroRNA-21 Modulates White Adipose Tissue Browning and Altered Thermogenesis in a Mouse Model of Polycystic Ovary Syndrome

Background and Aim: Polycystic ovary syndrome (PCOS) is associated with obesity, and white adipose tissue (WAT) and brown adipose tissue (BAT) dysregulation. However, the molecular mechanisms that mediate WAT and BAT derangements in PCOS are poorly understood. Subcutaneous (SC) WAT (SC-WAT) can transition to a beige/brite adipose tissue phenotype (browning) under altered thermogenic conditions. MicroRNAs play critical functions in brown adipocyte differentiation and maintenance. We aim to study the role of microRNA-21 (miR-21) in androgen-mediated browning and beiging derangements in both SC-WAT and BAT. Methods: Three week-old miR-21 knockout (miR21KO) or wild type (WT) female mice were treated with dihydrotestosterone (DHT, 8 mg/silastic tube) or vehicle for 90 days (n=12/grp). Body composition was measured by EchoMRI. Energy expenditure (EE), oxygen consumption (VO2), and carbon dioxide production (VCO2) were measured by indirect calorimetry. Glucose homeostasis was measured by oral glucose tolerance test (OGTT). HOMA-IR index was calculated from fasting serum glucose and insulin levels. Gene expression for browning (UCP1, Cox7a1, Elov3, Dio2 and Cidea) and beiging (Hspb7 and Txb1) markers was quantified by RT-qPCR in SC-WAT and BAT. Results: DHT increased body weight (25.07 ± 0.52 vs 21.79 ± 0.47 g, p<0.05) and fat mass (4.60 ± 0.46 vs 1.98 ± 0.12 g, p<0.05), impaired OGTT (186.10 ± 5.99 vs 250.70 ± 14.76 mg^.min/dL, p<0.05), and did not significantly change EE, VO2 or VCO2 in WT mice. All browning markers were downregulated by DHT in SC-WAT; however, only iodothyronine deiodinase 2 (Dio2) downregulation reached significance in both SC-WAT and BAT (by 53 and 40%, respectively) compared with the vehicle-treated mice. Beiging markers were significantly upregulated in SC-WAT and did not change in BAT. DHT-treated miR21KO mice showed attenuated DHT-mediated increase in body weight (23.84 ± 0.99 vs 25.07 ± 0.52 g, p<0.05) compared with WT mice. MiR-21 ablation did not modify DHT-mediated increase in fat mass or OGTT but worsened insulin resistance as calculated by the HOMA-IR index. Additionally, DHT-treated miR21KO mice showed a trend to reduced EE, VO2 and VCO2 values compared with DHT-treated WT. Gene expression analysis showed an exacerbation in DHT-mediated reduction in browning markers expression in the SC-WAT. Additionally, the induction in the adaptive beiging response was abolished in SC-WAT. Conclusion and Significance: These findings suggest that adipose tissue miR-21 may have a protective role in PCOS and ameliorate the DHT-mediated decrease in energy expenditure. Adipose tissue-specific modulation of miR-21 levels could be a novel therapeutic approach for the treatment of PCOS-associated metabolic derangements. (Supported by NIH grants NIGMS P20GM121334 to LLYC and DGR, NIDDK R21DK113500 to DGR, NIGMS P20GM104357 and NHLBI P01HL51971).

SARS-CoV-2 Viral Entry Proteins in Hyperandrogenemic Female Mice: Implications for Women with PCOS and COVID-19

SARS-CoV-2, the causative agent of COVID-19, infects host cells using the angiotensin I converting enzyme 2 (ACE2) as its receptor after priming by host proteases, including TMPRSS2. COVID-19 affects multiple organ systems, and male patients suffer increased severity and mortality. Polycystic Ovary Syndrome (PCOS) is the most common endocrine disorder in reproductive-age women and is characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovarian morphology. PCOS is associated with obesity and cardiometabolic comorbidities, both being risk factors associated with severe COVID-19 pathology. We hypothesize that elevated androgens in PCOS regulate SARS-CoV-2 entry proteins in multiple tissues increasing the risk for this population. Female mice were treated with dihydrotestosterone (DHT) for 90 days. Body composition was measured by EchoMRI. Fasting glucose was determined by an enzymatic method. mRNA and protein levels of ACE2, Tmprss2, Cathepsin L, Furin, Tmprss4, and Adam17 were quantified by RT-qPCR, Western-blot, or ELISA in tissues, serum, and urine. DHT treatment increased body weight, fat and lean mass, and fasting glucose. Ace2 mRNA was upregulated in the lung, cecum, heart, and kidney, while downregulated in the brain by DHT. ACE2 protein was upregulated by DHT in the small intestine, heart, and kidney. The SARS-CoV-2 priming proteases Tmprss2, Cathepsin L, and Furin mRNA were upregulated by DHT in the kidney. ACE2 sheddase Adam17 mRNA was upregulated by DHT in the kidney, which corresponded with increased urinary ACE2 in DHT treated mice. Our results highlight the potential for increased cardiac, renal, and gastrointestinal dysfunction in PCOS women with COVID-19.

CACNA1H variants are not a cause of monogenic epilepsy

CACNA1H genetic variants were originally reported in a childhood absence epilepsy cohort. Subsequently, genetic testing for CACNA1H became available and is currently offered by commercial laboratories. However, the current status of CACNA1H as a monogenic cause of epilepsy is controversial, highlighted by ClinGen's recent reclassification of CACNA1H as disputed. We analyzed published CACNA1H variants and those reported in ClinVar and found none would be classified as pathogenic or likely pathogenic per the American College of Medical Genetics classification criteria. Moreover, Cacna1h did not modify survival in a Dravet Syndrome mouse model. We observed a mild increase in susceptibility to hyperthermia-induced seizures in mice with reduced Cacna1h expression. Overall, we conclude that there is limited evidence that CACNA1H is a monogenic cause of epilepsy in humans and that this gene should be removed from commercial genetic testing panels to reduce the burden of variants of uncertain significance for healthcare providers, families and patients with epilepsy.

Effect of GLP-1 Receptor Agonists in the Cardiometabolic Complications in a Rat Model of Postmenopausal PCOS

Polycystic ovary syndrome (PCOS) is characterized by hyperandrogenism and ovulatory dysfunction. Women with PCOS have an elevated prevalence of cardiometabolic risk factors that worsen after menopause. Liraglutide (Lira), a glucagon-like peptide-1 receptor agonist, has shown beneficial metabolic effects in small clinic trials in reproductive-age women with PCOS. We have shown that chronic hyperandrogenemia in an experimental model of postmenopausal PCOS is associated with an adverse cardiometabolic profile and upregulation of the intrarenal renin-angiotensin system (RAS). We analyzed the effect of Lira in the cardiometabolic profile, intrarenal RAS, and blood pressure (BP) in postmenopausal PCOS. Four-week-old female Sprague Dawley rats were treated with DHT or placebo for 17 months. Lira administration during the last 3 weeks caused a bigger reduction in food intake, body weight, fat mass, and homeostasis model assessment of insulin resistance index in PCOS than in control rats. Moreover, Lira improved dyslipidemia and elevated leptin levels in PCOS. In contrast, Lira decreased intrarenal expression of RAS components only in the control group. Lira transiently increased heart rate and decreased BP in control rats. However, Lira did not modify BP but increased heart rate in PCOS. The angiotensin-converting-enzyme inhibitor enalapril abolished the BP differences between PCOS and control rats. However, Lira coadministration with enalapril further reduced BP only in control rats. In summary, Lira has beneficial effects for several cardiometabolic risk factors in postmenopausal PCOS. However, hyperandrogenemia blunted the BP-lowering effect of Lira in postmenopausal PCOS. Androgen-induced activation of intrarenal RAS may play a major role mediating increases in BP in postmenopausal PCOS.

Gene expression profiling in a mouse model of Dravet syndrome

Dravet syndrome is a severe, early-onset epileptic encephalopathy frequently resulting from de novo mutations of SCN1A. Mice with heterozygous deletion of Scn1a (Scn1a^+/-) model many features of Dravet syndrome, including spontaneous seizures and premature lethality. Scn1a^+/- mice exhibit variable phenotype penetrance and expressivity dependent upon the strain background. On the 129S6/SvEvTac (129) strain, Scn1a^+/- mice do not display an overt phenotype. However Scn1a^+/- mice on the [129S6xB6]F1 strain (F1.Scn1a^+/-) exhibit juvenile-onset spontaneous seizures and premature lethality. QTL mapping identified several modifier loci responsible for strain-dependent differences in survival of Scn1a^+/- mice, but these loci do not account for all the observed phenotypic variance. Global RNA-seq analysis was performed to identify additional genes and pathways that may contribute to variable phenotypes. Hippocampal gene expression was analyzed in wild-type (WT) and Scn1a^+/- mice on both F1 and 129 strains, at two time points during disease development. There were few gene expression differences between 129.WT and 129.Scn1a^+/- mice and approximately 100 genes with small expression differences (6-36%) between F1.WT and F1.Scn1a^+/- mice. Strain-specific gene expression differences were more pronounced, with dozens of genes with >1.5-fold expression differences between 129 and F1 strains. Age-specific and seizure-related gene expression differences were most prominent, with hundreds of genes with >2-fold differences in expression identified between groups with and without seizures, suggesting potential differences in developmental trajectory and/or homeostatic plasticity during disease onset. Global expression differences in the context of Scn1a deletion may account for strain-dependent variation in seizure susceptibility and survival observed in Scn1a^+/- mice.

Associations of urinary phthalate metabolites and lipid peroxidation with sperm mitochondrial DNA copy number and deletions

BACKGROUND

Phthalates, a chemical class of plasticizers, are ubiquitous environmental contaminants that have been associated with oxidative stress. Mitochondria DNA copy number (mtDNAcn) and DNA deletions (mtDNAdel) are emerging biomarkers for cellular oxidative stress and environment exposures.

OBJECTIVES

To examine associations of urinary phthalate metabolite and isoprostane concentrations on sperm mtDNAcn and mtDNAdel in male partners undergoing assisted reproductive technologies (ART).

METHODS

Ninety-nine sperm samples were collected from male partners undergoing ART at Baystate Medical Center in Springfield, MA as part of the Sperm Environmental Epigenetics and Development Study (SEEDS). Seventeen urinary phthalate metabolite concentrations were analyzed by the Centers for Disease Control using tandem mass spectrometry. Urinary 15-F2t-isoprostane concentrations, a biomarker of lipid peroxidation, were measured using a competitive enzyme-linked immunosorbent assay. A triplex qPCR method was used to determine the relative quantification of mtDNAcn and mtDNAdel.

RESULTS

Sperm mtDNAcn and mtDNAdel were positively correlated (Spearman rho = 0.31; p = .002). Adjusting for age, BMI, current smoking, race, and measurement batch, urinary monocarboxy-isononyl phthalate (MCNP) concentrations were positively associated with mtDNAcn (β = 1.63, 95% CI: 0.14, 3.11). Other urinary phthalate metabolite and isoprostane concentrations were not associated with sperm mtDNAcn or mtDNAdel.

CONCLUSIONS

Among this cohort of male ART participants, those with higher MCNP had higher mtDNAcn; other phthalate metabolites and isoprostane were not associated with mtDNAcn and mtDNAdel. Given our relatively small sample size, our results should be interpreted with caution. Future research is needed to replicate the findings in larger studies and among sperm samples obtained from the general population.