Edwina Brennan

Dr. Edwina Brennan

orcid

Research Focus & Metrics

Academic Career Length

18Years (2009-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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Verified
Journal Article
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ABAlexandra E. Butler
Alexandra E. Butler
MNManjula Nandakumar
Manjula Nandakumar
Thozhukat  Sathyapalan Thozhukat Sathyapalan
Thozhukat Sathyapalan
EBEdwina Brennan
Edwina Brennan
SAStephen L Atkin
Stephen L Atkin
Matrix metalloproteinases (MMPs) are M2 macrophage markers that are modulated by inflammation. A disintegrin and metalloproteinases (ADAMS) and those with thrombospondin motifs (ADAMTS) regulate the shedding of membrane-bound proteins, growth factors, cytokines, ligands, and receptors; MMPs, ADAMS, and ADAMTS may be regulated by tissue inhibitors of metalloproteinases (TIMPs). This study aimed to determine whether these interacting proteins were dysregulated in PCOS. A Somascan proteomic analysis of 12 MMPs, three of their inhibitors (TIMP-1, 2, 3), two ADAMS (9, 12), five ADAMTS (1, 4, 5, 13, 15), insulin-like growth factor binding protein-1 (IGFBP-1), and insulin-like growth factor-1 (IGF-1) was undertaken in a well-validated PCOS database of 143 women with PCOS and 97 controls. Women with PCOS had significantly higher levels of MMP-9 and lower levels of MMP-2, MMP-14, TIMP-2, IGFBP-1, and IGF-1 compared to the controls (p < 0.0001, p < 0.005, p < 0.04, p < 0.05, p < 0.0001, and p < 0.0001, respectively). No differences were observed for any other MMPs. The ADAMS or ADAMTS levels did not differ between groups. Body mass index (BMI) was correlated with MMP-9 (p < 0.01), MMP-1 (p < 0.05), MMP-2 (p < 0.05), MMP-10 (p < 0.005), MMP-12 (p < 0.005), ADAM-9 (p < 0.05), and IGFBP-1 (p < 0.0001), but only MMP-9 still differed after accounting for BMI. MMP-9/TIMP-1, MMP-9/TIMP-2, and MMP-9/TIMP-3 ratios were higher in the PCOS group (p < 0.01), whilst MMP-17/TIMP-1 and MMP-17/TIMP-2 were lower (p = 0.01). MMP-2/TIMP ratios showed no difference between groups. TIMP-2 was positively correlated with CRP (p < 0.01). MMP changes in PCOS are largely driven by BMI, though increased MMP-9 is BMI-independent, suggesting that any deleterious effects of MMP-9 would be potentially exacerbated by a concomitantly increased BMI. The significant increases in the MMP-9/TIMP ratios suggests MMP-9 overactivity in PCOS.

12 May 2025 in Journal of Xenobiotics
Verified
Journal Article
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AMAamer Mohammed
Aamer Mohammed
SAStephen L Atkin
Stephen L Atkin
EBEdwina Brennan
Edwina Brennan
Phthalates, a group of synthetic non-persistent organic chemicals commonly used as solvents and plasticisers, have been associated with a range of detrimental health effects. These endocrine disrupting chemicals (ECDs) may exert their effects through epigenetic changes such as altered microRNA (miRNA) expression. miRNAs are short non-coding endogenous RNA transcripts that are preferentially expressed in various tissues and cell types and can circulate in body fluids, thereby regulating gene expression and acting as mediators for intercellular communication. As miRNAs mostly target protein-coding transcripts, they are involved in nearly all networks that regulate developmental and pathological processes. In this review, we provide an overview of human, in vivo and in vitro studies assessing altered miRNA expression due to phthalate exposure and their biological effects. Importantly, this study suggests that the mechanism of phthalate action may in part be mediated by epigenetic changes, affecting a large number of different proteins. This is indicative that alterations in miRNA expression induced by phthalate exposure are then implicated in a wide range of health conditions, including reproductive dysfunction, oncogenesis, metabolic disorders, and neurodevelopmental outcomes. Exposure to phthalates and their metabolites predominantly results in the upregulation of miRNAs. Dysregulation of miR-34a, miR-15b, miR-141, miR-184, miR-19a, miR-125, and miR-let-7 were observed across several studies. More research involving human participants combined with mechanistic studies integrating mRNA target analysis would be beneficial in understanding the downstream effects of phthalate exposure on gene expression and grasping the broader biological implications.

18 September 2023 in Frontiers in Endocrinology
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Journal Article
Open access
EBEdwina Brennan
Edwina Brennan
ABAlexandra E. Butler
Alexandra E. Butler
DDDaniel S. Drage
Daniel S. Drage
TSThozhukat Sathyapalan
Thozhukat Sathyapalan
SAStephen L. Atkin
Stephen L. Atkin
Introduction: Polychlorinated biphenyls (PCBs), organic lipophilic pollutants that accumulate through diet and increase with age, have been associated with polycystic ovary syndrome (PCOS) and shown to affect microRNA (miRNA) expression. This work aimed to determine if PCBs were associated with circulating miRNAs and whether there were any correlations with serum PCB/miRNA levels and hormonal changes.Methods: 29 non-obese PCOS and 29 healthy control women, with similar age and body mass index (BMI), had their serum miRNAs measured together with 7 indicator PCBs (PCB28, PCB52, PCB101, PCB118, PCB138, PCB153, PCB180) using high resolution gas chromatography coupled with high resolution mass spectrometry.Results: In the combined study cohort, four miRNAs (hsa-miR-139-5p, hsa-miR-424-5p, hsa-miR-195-5p, hsa-miR-335-5p) correlated with PCBs, but none correlated with metabolic parameters. hsa-miR-335-5p correlated with FSH. When stratified, 25 miRNAs correlated with PCBs in controls compared to only one (hsa-miR-193a-5p) in PCOS; none of these miRNAs correlated with the metabolic parameters of BMI, insulin resistance, or inflammation (C-reactive protein, CRP). However, of these 25 miRNAs in controls, hsa-miR-26a-5p, hsa-miR-193a-5p, hsa-miR-2110 and hsa-miR-195-5p positively correlated with luteinizing hormone (LH), hsa-miR-99b-5p and hsa-miR-146b-5p correlated with estradiol, hsa-miR-193a-5p correlated with progesterone, hsa-miR-195-5p correlated with follicle stimulating hormone (FSH), and hsa-miR-139-5p and hsa-miR-146b-5p negatively correlated with anti-müllerian hormone (AMH) (all p<0.05). hsa-miR-193a-5p in PCOS cases correlated with estradiol.Conclusion: In this cohort of women, with no difference in age and BMI, and with similar PCB levels, the miRNAs correlating to PCBs associated with menstrual cycle factors in healthy menstruating controls versus the anovulatory PCOS subjects. The PCB-associated miRNAs did not correlate with non-reproductive hormonal and metabolic parameters. This suggests that PCB effects on miRNAs may result in changes to the hypothalamo-ovarian axis that may thus affect fertility.

7 December 2023 in Chemosphere
Verified
Journal Article
Open access
EBEdwina Brennan
Edwina Brennan
ABAlexandra E. Butler
Alexandra E. Butler
MNManjula Nandakumar
Manjula Nandakumar
KTKristie Thompson
Kristie Thompson
Thozhukat  Sathyapalan Thozhukat Sathyapalan
Thozhukat Sathyapalan
SAStephen L Atkin
Stephen L Atkin
Evidence suggests that endocrine disrupting chemicals (EDCs), commonly used in plastics and personal care products, may be associated with reduced levels of vitamin D. Therefore, this study examined the relationship between phthalate metabolites, 5-chloro-2-(2,4-dichlorophenoxy)phenol (triclosan; TCS) and bisphenols (BPs) with vitamin D3 (25(OH)D3) and active 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), and their relationship to calcium homeostasis. 57 female participants (age 31.8 ± 4.6 years; BMI 25.6 ± 3.7 kg/m2) were analyzed for urinary levels of phthalate metabolites, TCS and BPs, and serum levels of 25(OH)D3 and 1,25(OH)2D3, determined by isotope-dilution liquid chromatography tandem mass spectrometry. Serum calcium/calmodulin-dependent (CaM) associated proteins were determined by Slow Off-rate Modified Aptamer (SOMA)-scan. In the study cohort, 25(OH)D3 and 1,25(OH)2D3 levels were 22.9 ± 11.2 ng/mL and 0.05 ± 0.02 ng/mL, respectively: mono-3-carboxypropyl-phthalate (MCPP) correlated negatively with 25(OH)D3 (ρ = -0.53, p = 0.01). 28 of the 57 women recruited were 25(OH)D3 deficient, <20 ng/mL (50 nmol/L): in this group, mono-iso-butylphthalate (MiBP) and mono-butylphthalate (MBP) negatively correlated with 25(OH)D3; (ρ = -0.47, p = 0.049) and (ρ = -0.64, p = 0.005), respectively. EDCs did not correlate with 1,25(OH)2D3, measures of renal function or CaM proteins. These putative data indicate that MCPP is related to 25(OH)D3, while MiBP and MBP were related to vitamin D deficiency; however, no correlations were observed with TCS and BPs. No phthalate metabolites correlated with 1,25(OH)2D3, CaM associated proteins or renal function, suggesting that effects occur earlier in the vitamin D pathway and not through modulation of cellular calcium flux. The observed correlations are surprisingly strong compared to other predictors of 25(OH)D3, and larger studies adjusting for potential confounders are warranted.

5 June 2024 in Biomedicines
Verified
Journal Article
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ABAlexandra E. Butler
Alexandra E. Butler
Thozhukat  Sathyapalan Thozhukat Sathyapalan
Thozhukat Sathyapalan
PDPriya Das
Priya Das
EBEdwina Brennan
Edwina Brennan
SAStephen L Atkin
Stephen L Atkin
Background. Perfluorinated alkyl acids (PFAAs) are persistent organic pollutants affected by BMI and ethnicity, with contradictory reports of association with vitamin D deficiency. Methods. Twenty-nine Caucasian women with non-obese polycystic ovary syndrome (PCOS) and age- and BMI-matched Caucasian control women (n = 30) were recruited. Paired serum samples were analyzed for PFAAs (n = 13) using high-performance liquid chromatography–tandem mass spectrometry. Tandem mass spectrometry determined levels of 25(OH)D3 and the active 1,25(OH)2D3. Results. Women with and without PCOS did not differ in age, weight, insulin resistance, or systemic inflammation (C-reactive protein did not differ), but the free androgen index was increased. Four PFAAs were detected in all serum samples: perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS). Serum PFOS was higher in PCOS versus controls (geometric mean [GM] 3.9 vs. 3.1 ng/mL, p < 0.05). Linear regression modeling showed that elevated PFHxS had higher odds of a lower 25(OH)D3 (OR: 2.919, 95% CI 0.82–5.75, p = 0.04). Vitamin D did not differ between cohorts and did not correlate with any PFAAs, either alone or when the groups were combined. When vitamin D was stratified into sufficiency (>20 ng/mL) and deficiency (<20 ng/mL), no correlation with any PFAAs was seen. Conclusions. While the analyses and findings here are exploratory in light of relatively small recruitment numbers, when age, BMI, and insulin resistance are accounted for, the PFAAs do not appear to be related to 25(OH)D3 or the active 1,25(OH)2D3 in this Caucasian population, nor do they appear to be associated with vitamin D deficiency, suggesting that future studies must account for these factors in the analysis.

15 May 2023 in Biomedicines
Verified
Journal Article
Open access
PDF file
EBEdwina Brennan
Edwina Brennan
ABAlexandra E. Butler
Alexandra E. Butler
MNManjula Nandakumar
Manjula Nandakumar
Daniel DrageDaniel Drage
Daniel Drage
Thozhukat  Sathyapalan Thozhukat Sathyapalan
Thozhukat Sathyapalan
SAStephen L Atkin
Stephen L Atkin
In human population studies, organochlorine pesticides (OCPs) have been linked to vitamin D deficiency. Therefore, this study examined the association between OCPs, vitamin D3 (cholecalciferol, 25(OH)D3), and the active metabolite 1,25-dihydrovitamin D3 (1,25(OH)2D3) in a cohort of non-obese women. The serum samples of 58 female participants (age—31.9 ± 4.6 years; body mass index (BMI)—25.7 ± 3.7 kg/m2) were screened for 10 indicator OCPs. 25(OH)D3 and 1,25(OH)2D3 levels were determined via isotope dilution liquid chromatography tandem mass spectrometry. In this cohort, the 25(OH)D3 and 1,25(OH)2D3 levels were 22.9 ± 11.2 ng/mL and 0.05 ± 0.02 ng/mL, respectively, with 28 participants classified as 25(OH)D3-deficient (<50 nmol/L). In the study cohort, no correlations were found between individual or total OCPs (ƩOCPs) and 25(OH)D3. p,p′-dichlorodiphenyldichloroethylene (DDE) and ƩOCPs correlated positively with 1,25(OH)2D3, with the latter being negatively correlated with estimated glomerular filtration rate (eGFR). In women with sufficient 25(OH)D3 levels, p,p′-dichlorodiphenyltrichloroethan (DDT) was positively correlated with 1,25(OH)2D3, whilst in the deficient group, hexachlorobenzene (HCB) and p,p′-(DDE) were positively correlated with 1,25(OH)2D3, β-Hexachlorocyclohexane (HCH) was positively correlated with 25(OH)D3, and none of the OCPs were associated with measures of renal function. Overall, OCPs and ƩOCPs were not associated with 25(OH)D3, suggesting that they are unrelated to vitamin D deficiency, but p,p′-DDE and ƩOCPs correlated positively with active 1,25(OH)2D3, while ƩOCPs correlated negatively with eGFR, suggesting a possible renal effect. Analysis of vitamin D deficiency revealed an association between β-HCH and 25(OH)D3, and between HCB and p,p′-DDE and 1,25(OH)2D3, suggesting that OCP effects may be enhanced in cases of vitamin D deficiency.