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

Abstract

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.

Associations of sperm mitochondrial DNA copy number and deletion rate with fertilization and embryo development in a clinical setting

“…For mtDNAcn and mtDNAdel quantification, we used a modified version of a previously published triplex qPCR method (Phillips et al, 2014;Huffman et al, 2018). In brief, a segment of the minor arc of the mtDNA was targeted for mtDNAcn assessment due to its stability within the genome, lack of interaction with other targets and high amplification efficiency.…”

Mitochondrial DNA 4977 bp Deletion in Peripheral Blood is Associated with Polycystic Ovary Syndrome.

“…The quanti cation of mtDNA 4977 DR and CN were assessed simultaneously using an e cient and effective multiplex real-time PCR assay, which makes our results reliable [17,18]. Additionally, the sample size of our study was larger than those of previous similar studies assessing the association between mtDNA CN and PCOS.…”

“…RNAse P (ThermoFisher, cat# 4403326) was chosen as the genomic DNA reference. The reaction components (given in nal concentrations) were as follows: 250 µM for mtMajArc probes and primers, 250 µM for mtMinArc probes and primers, and 1× concentration for RNAse P. Real-time PCR was performed at the same cycling conditions as previously described: 95 °C for 10 min for activation, followed by 40 cycles of 95 °C for 15 s, 55 °C for 15 s, and 60°C [17,18]. Three technical replicates were performed.…”

Mitochondrial DNA 4977 bp Deletion in Peripheral Blood Is Associated With Polycystic Ovary Syndrome

“…To our knowledge, this study is the first to evaluate the association between the mtDNA 4977 DR and PCOS. The mtDNA 4977 DR and mtDNA CN were measured simultaneously using an efficient and effective multiplex real-time PCR assay, making our results reliable ( 26 , 32 ). Additionally, the sample size in this study was larger than that reported in previous similar studies.…”