Molecular basis of reduced birth weight in smoking pregnant women: mitochondrial dysfunction and apoptosis

Abstract

In utero exposure of fetuses to tobacco is associated with reduced birth weight. We hypothesized that this may be due to the toxic effect of carbon monoxide (CO) from tobacco, which has previously been described to damage mitochondria in non-pregnant adult smokers. Maternal peripheral blood mononuclear cells (PBMCs), newborn cord blood mononuclear cells (CBMCs) and placenta were collected from 30 smoking pregnant women and their newborns and classified as moderate and severe smoking groups, and compared to a cohort of 21 non-smoking controls. A biomarker for tobacco consumption (cotinine) was assessed by ELISA (enzyme-linked immunosorbent assay). The following parameters were measured in all tissues: mitochondrial chain complex IV [cytochrome c oxidase (COX)] activity by spectrophotometry, mitochondrial DNA levels by reverse transcription polymerase chain reaction, oxidative stress by spectrophotometric lipid peroxide quantification, mitochondrial mass through citrate synthase spectrophotometric activity and apoptosis by Western blot parallelly confirmed by TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labelling) assay in placenta. Newborns from smoking pregnant women presented reduced birth weight by 10.75 percent. Materno-fetal mitochondrial and apoptotic PBMC and CBMC parameters showed altered and correlated values regarding COX activity, mitochondrial DNA, oxidative stress and apoptosis. Placenta partially compensated this dysfunction by increasing mitochondrial number; even so ratios of oxidative stress and apoptosis were increased. A CO-induced mitotoxic and apoptotic fingerprint is present in smoking pregnant women and their newborn, with a lack of filtering effect from the placenta. Tobacco consumption correlated with a reduction in birth weight and mitochondrial and apoptotic impairment, suggesting that both could be the cause of the reduced birth weight in smoking pregnant women.

Placental mitochondrial DNA and CYP1A1 gene methylation as molecular signatures for tobacco smoke exposure in pregnant women and the relevance for birth weight

“…We showed that placental mtDNA content and methylation levels were responsive to tobacco smoke exposure during pregnancy indicating that mtDNA is a sensitive marker of mitochondrial damage and dysfunction as proposed by Sahin et al [10]. In addition to other studies reporting changes in placental mtDNA content in smoking mothers [7, 8] or mothers exposed to air pollution [29], we provide here the first epidemiological evidence of altered methylation levels at specific loci of the mitochondrial genome of placental tissue in response to tobacco smoke exposure during pregnancy. We suggest that pollution-induced epigenetic modifications of the mitochondrial genome may prime alterations in mtDNA content by regulating mitochondrial function and biogenesis [35].…”

Mitochondrial DNA disturbances and deregulated expression of oxidative phosphorylation and mitochondrial fusion proteins in sporadic inclusion body myositis

“…These proteins were assessed through immunoblotting using SDS/7/13% PAGE and immunodetection using previously described reagents and antibodies [22]. Mitochondrial values normalized to nuclear-encoded COX proteins were expressed as the COX-II:COX-IV ratio, and absolute values of COX-II and COX-IV were normalized with a loading control (α-tubulin for muscle samples and β-actin for PBMC samples) and expressed as the COX-II:α-tubulin and COX-IV:α-tubulin ratios in muscle or the COX-II:β-actin and COX-IV:β-actin ratios in PBMCs.…”

“…CS is a mitochondrial enzyme of the citrate cycle widely considered to be a reliable marker of mitochondrial content, and VDAC1 [22] is an outer membrane anion channel also considered to be a mitochondrial mass marker [22]. CS activity was expressed as nmol/min per mg of protein and VDAC1 expression was normalized by α-tubulin in muscle and by β-actin in PBMCs, both of which are validated proteins for assessing total cell loading mass and expressed as the VDAC1:α-tubulin ratio in muscle or the VDAC-1:β-actin ratio in PBMCs.…”

“…This PBMC model is widely feasible for the evaluation of mitochondrial function [21][22][23]. Thus, we designed the present study to evaluate mitochondrial dysfunction in both muscle and PBMCs of sIBM patients to correlate dysfunction severity with genetic and molecular mitochondrial alterations, and determine their potential association with the deregulation of mitochondrial dynamics.…”

Efeitos da exposição materna à poluição na biometria e hemodinâmica fetais

“…Alguns estudos têm investigado os mecanismos subjacentes. Garrabou et al (93) observaram que a redução do peso ao nascimento está associada ao dano mitocondrial. Ademais, Ingvarsson et al (93) observaram que o impacto negativo do tabagismo materno no peso, comprimento e CC ao nascimento pode ser causado pela diminuição do transporte de oxigênio para o feto e por concentrações reduzidas de insulina e fator de crescimento semelhante à insulina tipo 1.…”