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Mitochondrial Toxicity in Human Pregnancy: An Update on Clinical and Experimental Approaches in the Last 10 Years



Mitochondrial toxicity can be one of the most dreadful consequences of exposure to a wide range of external agents including pathogens, therapeutic agents, abuse drugs, toxic gases and other harmful chemical substances. However, little is known about the effects of mitochondrial toxicity on pregnant women exposed to these agents that may exert transplacental activity and condition fetal remodeling. It has been hypothesized that mitochondrial toxicity may be involved in some adverse obstetric outcomes. In the present study, we investigated the association between exposure to mitochondrial toxic agents and pathologic conditions ranging from fertility defects, detrimental fetal development and impaired newborn health due to intra-uterine exposure. We have reviewed data from studies in human subjects to propose mechanisms of mitochondrial toxicity that could be associated with the symptoms present in both exposed pregnant and fetal patients. Since some therapeutic interventions or accidental exposure cannot be avoided, further research is needed to gain insight into the molecular pathways leading to mitochondrial toxicity during pregnancy. The ultimate objective of these studies should be to reduce the mitochondrial toxicity of these agents and establish biomarkers for gestational monitoring of harmful effects.
Int. J. Environ. Res. Public Health 2014, 11, 9897-9918; doi:10.3390/ijerph110909897
International Journal of
Environmental Research and
Public Health
ISSN 1660-4601
Mitochondrial Toxicity in Human Pregnancy: An Update on
Clinical and Experimental Approaches in the Last 10 Years
Constanza Morén
*, Sandra Hernández
, Mariona Guitart-Mampel
* and
Glòria Garrabou
Muscle Research and Mitochondrial Function Laboratory, Cellex-IDIBAPS-Faculty of
Medicine-University of Barcelona, Internal Medicine Service-Hospital Clínic of Barcelona,
Barcelona 08036, Spain; E-Mail:
Centro de Investigación Biomédica en Red (CIBER) de Enfermedades Raras, CIBERER,
Valencia 46010, Spain; E-Mail:
Materno-Fetal Medicine Department, Clinical Institute of Gynaecology, Obstetrics and
Neonatology, Barcelona 08025, Spain
* Authors to whom correspondence should be addressed; E-Mails: (C.M.); (M.G.-M.); Tel.: +34-93-227-5400 (ext. 2907) (C.M.);
Fax: +34-93-227-9365 (C.M.).
Received: 31 July 2014; in revised form: 5 September 2014/ Accepted: 17 September 2014/
Published: 22 September 2014
Abstract: Mitochondrial toxicity can be one of the most dreadful consequences of exposure
to a wide range of external agents including pathogens, therapeutic agents, abuse drugs, toxic
gases and other harmful chemical substances. However, little is known about the effects of
mitochondrial toxicity on pregnant women exposed to these agents that may exert
transplacental activity and condition fetal remodeling. It has been hypothesized that
mitochondrial toxicity may be involved in some adverse obstetric outcomes. In the present
study, we investigated the association between exposure to mitochondrial toxic agents and
pathologic conditions ranging from fertility defects, detrimental fetal development and
impaired newborn health due to intra-uterine exposure. We have reviewed data from studies
in human subjects to propose mechanisms of mitochondrial toxicity that could be associated
with the symptoms present in both exposed pregnant and fetal patients. Since some
therapeutic interventions or accidental exposure cannot be avoided, further research is
needed to gain insight into the molecular pathways leading to mitochondrial toxicity
during pregnancy. The ultimate objective of these studies should be to reduce the
Int. J. Environ. Res. Public Health 2014, 11 9898
mitochondrial toxicity of these agents and establish biomarkers for gestational monitoring
of harmful effects.
Keywords: Mitochondria; toxic effects; pregnancy; adverse obstetric outcome
1. Introduction
1.1. Mitochondrial Physiology
Mitochondria are cell organelles located in the cytoplasm of most of the eukaryotic cells [1].
Mitochondria are essential for cell viability because of their involvement in many important processes,
such as heat production, energy supply, cell respiration, calcium homeostasis and the anabolism and
catabolism of numerous metabolites [2], among others. However, in pathological conditions,
mitochondria are also the main source of reactive oxygen species (ROS) production and apoptosis.
These organelles are the energy powerhouse of cells as they provide energy through the formation of
molecules of adenosine triphosphate (ATP), the major energy source of the cells. The synthesis of ATP is
coupled to cell respiration and oxygen consumption in the mitochondrial respiratory chain (MRC).
Mitochondria are constituted by a double membrane; the external membrane, which is permeable to
many solutes and makes the interchange of molecules with the cytosol possible, and the internal
membrane, which is highly impermeable and is a folded structure constituting the mitochondrial cristae,
where the enzymatic complexes of the MRC are located. Together with chloroplasts, mitochondria are
the only organelles containing their own genetic material, the mitochondrial DNA (mtDNA) encoding
for some proteins of the MRC and autonomous transcriptional and translational machinery. Human
mtDNA is a 16.6 kb double-stranded circular and covalently closed molecule encoding for 13 MRC
proteins, two mitochondrial ribosomal RNA and 22 mitochondrial transfer RNA essential for the
translation of mitochondrial-encoded proteins [3]. The remaining proteins located in the mitochondria
(approximately 1500 in mammals) are encoded in the nucleus. Consequently, intergenomic
communication between these two entities is essential for adequate mitochondrial function. In this
context, a decrease of mtDNA levels (mtDNA depletion) can ultimately lead to severe mitochondrial
dysfunction and energetic cell impairment. Additionally, mitochondrial disarrangements can arise
during many other steps of mitochondrial function (biogenesis, bioenergetics, dynamics or turnover),
independently of mtDNA depletion.
Mitochondrial DNA is exclusively transmitted by the maternal lineage, contrarily to nuclear DNA that
is transmitted by both parents, and the variation in number of both mitochondria and mtDNA content varies
widely depending on the cell type and stage of development. Somatic cells contain from hundreds to
thousands of mitochondria, each carrying from 2 to 10 genomes per organelle [3], and postmitotic tissues,
which are highly-energetic and dependent on oxidative metabolism, present higher loads of mitochondria
and mtDNA content. Accordingly, a physiologic state associated with a high energy demand, such as
fertilization and pregnancy, may require greater mitochondrial activity.
Int. J. Environ. Res. Public Health 2014, 11 9899
The oocyte is the only reproductive cell that provides mitochondrial load to the future embryo and
posterior newborn. Thus, mitochondria are maternally inherited and a sufficient energy supply from
oocyte mitochondria is critical to trigger oocyte viability and future embryo development. The oocyte is
the largest human cell (on average 300 times bigger than other somatic cells) and contains a large amount
of mitochondria that represent at least 23% of the ooplasm [4]. Depending on the stage of development
of the germinal cells, the number of mitochondria present ranges widely from 10 in germinal cells, 1000
in blastocytes to 100,000 in mature oocytes. Oocytes are packed with mitochondria, each of which has
its own genome. The mtDNA copy number per mature human oocyte is about 100,000600,000
molecules, compared with the 50010,000 molecules for the remaining somatic cells [5,6]. However,
this very large number of mtDNA per oocyte is not due to increased mtDNA content per mitochondria
but rather to an increased number of mitochondria per oocyte. In fact, along oogenesis, the number of
copies of mtDNA is thought to be reduced per organelle in a process known as the mitochondrial
bottleneck. The aim of this evolutionary strategy is to finally contain one mtDNA molecule per
mitochondrion to avoid heteroplasmic segregation through the maternal lineage [7], thereby avoiding
the coexistence of wild type and mutated molecules of mtDNA within the same entity (mitochondria,
oocyte and future embryo). However, this makes oocyte mitochondria especially vulnerable to mtDNA
depletion and also makes oocytes especially sensitive to factors causing mtDNA depletion or
mutagenesis, such as infections, drugs and toxic substances, among others.
The involvement of mitochondria in fertility outcome can be easily estimated in vitro. It has been
reported that 50% of human in vitro fertilization (IVF) attempts fail during the first week of
development [8]. The main causes of this developmental failure, apart from chromosomic alterations [9]
(deficiency in oocyte maturation [10], lack of activation of embryonic genome [11] or sub-optimal
culture conditions of both gametes and embryos [12,13]) have been directly or indirectly related to
mitochondrial function and ROS production. Cohen et al. reported that ooplasm transfer from a young
donor oocyte into a non-fertile oocyte partially restores the reproductive capacity in the oopausic oocyte,
and they suggested that “fertility” restoration may be due to mitochondrial transference [14].
Other studies have shown that both mitochondrial and mtDNA content reflect oocyte variability and
fertilization outcome [4]. Thus, in vitro studies have suggested that mitochondria in the oocyte contribute
to successful fertilization and embryonic development.
Although spermatozoa do not provide mitochondria to the future embryo, mitochondrial function is
essential for flagellum motility and male fertility in the spermatozoa.
Once fertilization and implantation have been achieved, mitochondrial activity is essential along
pregnancy to provide energy and metabolites for the development of the embryo. Blastocytes and future
embryo cells need an enormous supply of energy to feed constant cell division, migration and
differentiation. Additionally, mitochondria regulate apoptosis development in this crucial stage of life
to decide which cells or tissues need to be eliminated for further embryo development. Consequently,
exposure of mitochondria to toxic agents during pregnancy can alter the development of the embryo and
may have important consequences in the perinatal outcome and health of the newborn.
Int. J. Environ. Res. Public Health 2014, 11 9900
1.2. Mitochondrial Pathology
Mitochondria are essential for life and the presence of mitochondrial alterations in a given organism
may lead to the development of mitochondriopathies [15]. Mitochondrial diseases are classified as
inherited or acquired (derived from toxic substances), with both sharing similar clinical consequences.
Mitochondria are present in almost all the tissues of the organism, and therefore mitochondrial
diseases can be translated into a wide spectrum of clinical manifestations [16]. Mitochondrial diseases
lack therapeutic treatments and are characterized by the degeneration of tissues, especially those which
are highly energetic such as muscle and nervous tissue. The symptoms range from myopathy,
neuropathy, encephalopathy, lactic acidosis, to lipodystrophy or deafness [15]. In the context of
pregnancy, mitochondrial dysfunction has been associated with increased rates of preterm delivery,
stillbirth, intrauterine growth restriction (IUGR), and sudden infant death [17].
The mutations responsible for genetic mitochondrial diseases can be present in both the nuclear or
mitochondrial genome. Genetic mitochondrial diseases are present in 1 in 5000 newborns and 1 in
200 women may carry one of these deleterious mutations. Nuclear mutations are paternal and maternally
inherited due to Mendelian heritance and can be prevented through genetic counseling and
pre-implantational diagnosis. However, inherited or acquired mutations in mtDNA present a
random maternal inheritance pattern due to heteroplasmy that hampers both the diagnosis and prevention
of mitochondrial diseases.
Genetically inherited mitochondrial diseases affect the offspring of carriers of nuclear or mtDNA
mutations. However, acquired mitochondrial diseases are potentially caused by exposure to multiple
exogenous factors such as: biologic agents, therapeutic drugs, abuse drugs, toxic gases and chemical
substances, regardless of the genetic environment.
These toxic compounds usually exert their damaging effects by impairing a specific genetic,
biochemical or molecular mitochondrial pathway [18]. Nonetheless, in cases of chronic abuse, most of
these toxic agents finally lead to general mitochondrial dysfunction which can compromise cellular and
tissue viability and, in some cases, be life threatening [17]. Mitochondrial recovery may occur once the
exogenous toxicant is withdrawn [19], and the clinical effects caused by these agents normally disappear
with discontinuation of exposure. However, when this is not possible, clinicians must manage the
secondary effects caused by mitochondrial toxicity. Mitochondrial therapies designed to revert
mitochondrial-induced damage (such as antioxidants or vitamins, among others) are currently being
developed but, are not yet available in routine clinical practice, especially for the management of
pregnancy or newborns. These treatments involve symptomatic and supportive therapies. Thus, to date,
the prevention of mitochondrial acquired diseases and mitochondrial toxicity is the prophylactic
therapeutic option of choice [20].
Although mitochondrial toxicity has been widely studied in adults, there is relatively little information
on these toxicities within the context of human pregnancy, particularly intra utero exposure and the
potential impact on fetal development and the future of the newborn. The objective of this work was,
therefore, to review mitochondrial toxicity in fertility and human pregnancies.
Int. J. Environ. Res. Public Health 2014, 11 9901
2. Methods
We reviewed all the literature concerning fertilization, obstetric and perinatal outcomes due to
exposure to any mitochondrial toxic agent in humans as an update on the studies performed in these
areas in the last 10 years.
We performed a systematic review through PubMed/MEDLINE using keyword search terms related
to mitochondrial toxic agents, in the English language, and involving human participants.
The literature review included all the articles published in peer-review journals related to data on
mitochondrial toxicity in pregnancies exposed to toxic compounds, following the same model of
mitochondrial studies of toxicities derived from exposure to determined toxic agents described in
non-pregnant adults. The literature review was conducted with searches in PubMed using combinations
of the fixed medical subject headings (MeSH): pregnancy and mitochondria, together with the variable
headings, related to poisonous exposure agents. A significant amount of literature was found with the
association of mitochondria and pregnancies. However, in most cases, the number of documents
available considerably decreased when a third factor, related to the toxic agent, was added to the search.
Except for some punctual cases, we restricted our review to material published in the last 10 years
(20042014) to obtain the most recent information in this field.
All English language articles with a full-text version reporting data about mitochondrial toxicity in
human pregnancies exposed to toxic agents with potential capability of causing mitochondrial alterations
were included in the review. Articles lacking an English abstract were excluded.
The references of these articles were also scanned for potential additional material, but this did not yield
many studies fulfilling the study criteria. Studies including animal models or information of highly
specific basic sciences were excluded from the present review, except for those describing the
mechanism of toxicity of a studied agent or those needed to reinforce the strong need for further research
in human pregnancies due to extensive evidence of toxicity in experimental models.
We found very few studies describing an association between mitochondrial toxicity and human
pregnancy or reproductive outcome with respect to fertilization or fetal development. Nonetheless, we have
summarized the information available regarding exposure to: biologic agents (human immunodeficiency
virus, HIV and hepatitis C virus, HCV), drugs (antivirals, antipsychotics, antibiotics, hypolipemia drugs,
antidiabetics, non-steroidal anti-inflammatory drugs (NSAIDs), anaesthetics, chemotherapy drugs,
antiarrhythmics, antimalarials and fungicides), abuse drugs (such as tobacco and alcohol), toxic gases
(as carbon monoxide) and chemical substances (including pesticides).
3. Results
3.1. Mitochondrial Toxicity of Biologic Agents during Pregnancy; The Effect of HCV or HIV
Both HCV and/or HIV-pregnancies have been associated with an increased frequency of adverse
obstetric and perinatal outcomes both of which result in maternal or neonatal complications [21,22].
The HCV has recently been related to an increase of oxidative stress and mtDNA alterations in
non-pregnant infected patients. However, to our knowledge, scarce information is available on
HCV-infected pregnant women to assess viral-mediated mitochondrial damage and its association with
adverse perinatal outcomes [23].
Int. J. Environ. Res. Public Health 2014, 11 9902
The mechanisms underlying vertical transmission of HCV are poorly understood. Intrauterine
transmission during pregnancy and infection at the time of delivery are both possible. To date, no special
measures are taken for HCV-pregnancies to avoid mother-to-child transmission (MTCT).
On the other hand, in non-pregnant patients, HIV is known to cause diffuse mitochondrial impairment
by promoting cell death through apoptosis triggered by certain viral proteins [24]. Mitochondrial
alterations associated with HIV itself were first described in 2002 [25] in a study in which mtDNA
depletion was reported in peripheral blood mononuclear cells (PBMC) of HIV-patients who had never
received antiretroviral (ARV) therapy [25]. Thereafter, mitochondrial dysfunction was also
demonstrated in naïve patients [26]. However, only a few studies have analyzed the toxic mitochondrial
effects of HIV-infection in human pregnancies.
The exact mechanism of MTCT of HIV remains unknown. Transmission may occur during
intrauterine life, delivery, or breastfeeding. Advanced maternal disease, probably due to high viral load,
is the greatest risk factor for vertical transmission. Untreated HIV-pregnancies are associated with high
transmission rates of up to 2530%. With the implementation of universal prenatal HIV-testing,
counseling, ARV medication, delivery by cesarean section prior to the onset of labor, and avoidance of
breastfeeding, MTCT has decreased to less than 12% in developed countries [27,28].
The administration of ARV to avoid HIV-MTCT has reduced viral burdens at delivery and,
consequently, viral-mediated mitochondrial damage should be minimal [29]. However, some antiviral
drugs have been shown to cause secondary mitochondrial toxicity. These adverse effects during
pregnancy are reviewed below in the section on “Drugs”. Most of the studies reporting mitochondrial
damage in perinatal HIV-exposed newborns include information about transplacentally ARV-derived
adverse effects, rather than describe the effects of the virus itself, regardless of the therapy used.
However, the inflammatory environment created by both the HCV and HIV (pro-inflammatory cytokine
expression or humoral and cellular immune activation, among others) [30] may also reduce the fertility
and pregnancy outcome of infected women independently of ARV. Thus, further research on
mitochondrial toxicity due to viral infection during pregnancy is required for better understanding of
mitochondrial implications in obstetric outcomes in these pregnancies.
3.2. Drugs
3.2.1. Antivirals
Concerning antivirals against HIV, international guidelines recommend the administration of ARV,
at least during the last trimester of gestation, to decrease the viral load at delivery and the risk
of MTCT.
The potential clinical risks associated with ARV exposure in HIV-pregnant women, fetuses and
infants have been described in observational studies with varying degrees of evidence and conflicting
results [3135]. Antiretroviral drugs are essential in the treatment and prevention of HIV-infection and
transmission. Although their use before, during and after pregnancy is considered safe for both the
mother and child, there are still lingering concerns about their long-term health consequences and the
ramifications of their effects on lipid, glucose, intermediary and mitochondrial metabolism [36].
Int. J. Environ. Res. Public Health 2014, 11 9903
Additionally, ARV have been associated with adverse pregnancy outcomes such as preeclampsia, stillbirth,
preterm birth and low birth weight, although controversial results have been published [3741].
Antiretroviral-driven mitochondrial toxicity has been especially associated with the administration of
nucleoside analogs which are known to inhibit the mitochondrial enzyme responsible for mtDNA
replication and repair (DNA polymerase gamma), reviewed in [42]. Nucleoside analog treatment has
been widely associated with mtDNA point mutations, deletions and depletion responsible for adverse
manifestations in treated patients including lactic acidosis, lipodystrophy as well as infertility [43].
Infertile HIV-infected women on highly active ARV therapy showed oocyte mtDNA depletion of 32%,
which was even greater in HIV-infected women who failed to become pregnant after IVF [44].
The authors of this study did not find any correlation between mtDNA oocyte content and the
immunovirological status of pregnant women. Additionally, oocytes have no HIV-receptors for viral
entrance, suggesting that the alterations detected may be due to drug toxicity rather than viral infection.
The mitochondrial toxicity of ARV may trigger the impairment of female fertility but, additionally, when
pregnancy is achieved, mitochondrial toxicity may increase adverse human pregnancy outcomes. Negative
mitochondrial and clinical effects of ARV therapy have been reported in HIV-pregnancies [45].
Most of the mitochondrial studies performed in HIV-pregnancies have described an increased
frequency of adverse obstetric events in the HIV-cohort [4549]. Some controversial results in
HIV-exposed infants reported increased levels of fetal leukocyte mtDNA content [50] accompanied by
reduced umbilical cord blood mitochondrial enzyme expression, leading the authors to hypothesize a
compensatory mechanism to overcome HIV/ARV-associated mitochondrial toxicity [50]. However,
most of the studies reported different degrees of evidence of increased mitochondrial toxicity and,
in some cases, the development of apoptosis in maternal, fetal or even placental tissue [4549].
The small sample size of these studies makes it difficult to link mitochondrial toxicity or the development
of apoptosis with adverse pregnancy outcomes because of the reduced statistical power when
classifying the HIV-cohort according to successful pregnancy results. Further studies with larger sample
sizes are required.
3.2.2. Antipsychotics, Antibiotics, Hypolipemia Drugs and Antidiabetics, Non-Steroidal
Anti-inflammatory Drugs (NSAIDs), Anesthetics, Chemotherapy Drugs, Antiarrhythmics,
Antimalarials and Fungicides
Similarly, many other drugs currently used in clinical practice as acute treatments in non-pregnant
subjects have been described to cause mitochondrial toxicity by impairing different pathways of
mitochondrial function. Mitochondrial respiratory chain function has been reported to be blocked by
some antibiotics (including piericidin A or antimycin A) [51], certain anaesthetic drugs [52] or some
barbiturates [53], antineoplastic treatments (including flutamide, tamoxifen and doxorubicin) [54,55]
and fungicidal agents (such as myxothiazole, sodium azide or rutamycin) [56]. Some of these agents
may lead to the impairment of cell respiration (fibrates) [57]. Other drugs can act as uncouplers of the
oxidative phosphorylation system (antibiotics such as valinomycin and gramicidin, local anaesthetics
and antineoplastics including flutamide, tamoxifen and doxorubicin) [55]. Likewise, other drugs may
prevent ATP production (antibiotics such as oligomycin or local anaesthetic drugs), inhibit protein
synthesis (antibiotics including chloramphenicol, tetracycline, erythromycin, eperezolid, linezolid and
Int. J. Environ. Res. Public Health 2014, 11 9904
aminoglycosides) [19,58], decrease electron transfer (anticholesterolemics) or membrane potential,
impair mitochondrial lipid metabolic pathways (barbiturates) or increase apoptosis (including
benzodiazepines) [59]. Such mitochondrial disturbances have been reported to cause adverse effects
including deafness [60], peripheral neuropathy [61], hyperlacatemia, lactic acidosis [62] and
gastrointestinal, dermatological or hematological alterations, myopathic syndrome or gastrointestinal
disturbances, among others [63]. Specific safety and mitochondrial toxic studies in human pregnancies
are lacking for most of these drugs. Indeed, most of these treatments are contraindicated in pregnancy
(for instance, chloramphenicol, tetracyclines, linezolid, most aminoglycosides, oral hypolipemiadrugs
or fungicides). However, during pregnancy, women could be exposed to these substances in some
exceptional cases: when they are not aware of their pregnancy status, as punctual and short interventions
in case of emergency (for instance erythromycin) or as mandatory treatments for chronic diseases,
among others.
This is the case of drugs used for mental health disorders such as schizophrenia, bipolar disorder, and
psychotic depression, which are not rare in women of childbearing age. Similar to ARV, antipsychotic
drugs in the management of antenatal psychiatric disorders are not of choice but are strongly
recommended or even mandatory in psychiatric patients during pregnancy. Antipsychotics are
associated with increased gestational weight and diabetes and increased risk of preterm birth. The effects
of antipsychotics on low birth weight or malformations are inconclusive. From a mitochondrial point of
view, antipsychotics have been described to inhibit MRC complex I function, causing an increase in the
levels of oxidative stress in non-pregnant adults [64]. However, no study was found regarding the
analysis of mitochondrial toxicity of neuroleptic drugs in human pregnancies.
On the other hand, although the hypoglycemiant drugs are not administered during gestation, insulin
is allowed. Gestational diabetes is a condition characterized by high blood sugar (glucose) levels that is
first recognized during pregnancy. The condition occurs in approximately 4% of all pregnancies and is
associated with fetal macrosomia. In addition, hypertension and preeclampsia occur more commonly in
women with gestational diabetes. Mitochondrial dysfunction has been reported during human pregnancy
with gestational diabetes mellitus [65]. In general, some antidiabetic drugs have been related to
mitochondrial damage through specific MRC impairment. For example, metformin specifically inhibits
MRC complex I activity [66]. However, information regarding the consequences of insulin
administration during human pregnancy and the potential mitochondrial toxicity derived from in utero
exposure is scarce. Few works on this topic have been performed in animal models and report null effects
(at least obvious) on progeny at delivery. On the contrary, indirect metabolic and mitochondrial toxicity
has been reported with the development of diabetes during pregnancy due to high glucose levels that
reduce fatty acid oxidation and increase triglyceride accumulation in human placenta [67], thereby
causing a metabolic and energetic imbalance that may endanger embrionary development.
Nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin or ibuprofen, are among the drugs
most commonly prescribed worldwide to reduce inflammation and pain through cycloxygenase
inhibition and a consequent decrease in prostaglandin production. Nonsteroidal anti-inflammatory drugs
have been reported to cause an uncoupling of the oxidative phosphorylation pathway, an increase in
resting state respiration, a decrease in ATP synthesis and mitochondrial membrane potential, inhibition
of adenine nucleotide translocase and an alteration in mitochondrial lipid metabolic pathways with
potential implications by way of the gastrointestinal damage associated with NSAID administration in
Int. J. Environ. Res. Public Health 2014, 11 9905
non-pregnant adults [59]. However, scarce data are available on the potential effects in human
pregnancies. Ibuprofen is not prescribed during pregnancy due to adverse effects on fetal circulation,
but aspirin is recommended in pregnancies complicated by preeclampsia, repetitive miscarriages or
previous fetal death.
Antiarrhythmic and antimalarial drugs such as quinidine have also been described to be mitotoxic
agents, with quinidine being particularly associated with ATP-synthase inhibition [68]. The potential
induction of oxidative stress has been associated with some antimalarial drugs [69], but little is known
about their mechanisms of toxicity or adverse outcomes in pregnancy. There are few studies on the
pharmacokinetics, safety and efficacy of antimalarials in human pregnancies. Several decades ago [70]
one study assessed the effect of the antimalaria drug pyrimethamine in pregnancy [70,71], reporting
altered embryonal hepatocytes with destructive changes in mitochondria.
In summary, although potential exposures with mitotoxic drugs during fertilization or pregnancy may
be considered harmful, few studies (if any) have evaluated the clinical consequences of the use of such
products in pregnant women and their potentially derived mitochondrial toxicities. Consequently, drug
exposure should be minimized or avoided during pregnancy, especially when considering the above
mentioned medications, except under explicit medical prescription and clinical supervision.
3.3. Abuse Drugs, such as Tobacco or Alcohol
It is widely known that tobacco causes serious adverse alterations in the organism. Regarding fertility,
it has been described that the exposure to cigarette smoke causes antral follicle destruction and oocyte
dysfunction through oxidative stress [72]. Despite a reduction in tobacco consumption during pregnancy, it
is estimated that about 2050% of pregnant women smoke during pregnancy in developed countries [18].
From a mitochondrial point of view, the carbon monoxide (CO) present in tobacco smoke binds to
the heme group of the MRC complex IV, the enzyme responsible for the reduction of oxygen
molecules into water, triggering a decrease in cell respiration and a consequent increase of ROS
production and oxidative stress damage [7376]. Tobacco consumption in human pregnancies has been
associated with a wide range of adverse obstetric outcomes (preterm delivery, stillbirths, sudden infant
death and respiratory problems during childhood), being IUGR the most frequent of these toxic
manifestations [77,78]. Studies in human pregnancies have associated maternal smoking with mtDNA
depletion and respiratory chain complex III deficiency in placenta [18]. In our experience [79], typical
mitochondrial toxic hallmarks of smoking in pregnant women are also present in both placenta and cord
blood cells of the newborn, suggesting that mitochondrial disturbances may be involved in IUGR. Such
mitochondrial abnormalities due to in utero exposure to tobacco smoke include MRC IV inhibition,
increased oxidative stress, decreased mtDNA content and raised apopototic levels which are responsible
for potential adverse obstetric outcome. Placental apoptosis has been previously associated with a higher
incidence of adverse obstetric outcomes, especially preeclampsia [80,81], in non-smoking women.
Interestingly, IUGR may also be associated with apoptosis in smoking pregnant woman, suggesting that
it may be the basis of both phenomena, regardless of the idiopathic or toxic origin.
Alcohol abuse has been widely associated with several medical and social problems and its use has
been related to the intoxication of the central nervous system, impaired brain activity, poor motor
coordination, and behavioral changes. Acute alcohol consumption affects carbohydrate, fat and protein
Int. J. Environ. Res. Public Health 2014, 11 9906
metabolism. Mitochondria are essential for the conversion of acetaldehyde into acetate and the
generation of increased amounts of NADH, as reviewed [82]. Therefore, during ethanol oxidation, there
is an increase in the NADH/NAD
ratio followed by alterations of the cellular redox state and triggering
of a number of adverse effects, associated with alcohol consumption [83].
Alcohol does not bind to any tissue or plasma proteins because of its soluble nature, however, it can
cross the blood brain barrier and placenta [84]. Alcohol dependence during pregnancy has been
associated with a multitude of adverse obstetric outcomes and adverse effects in offspring (being the
fetal alcohol syndrome the most extreme) including pre- and post-natal growth retardation, newborn
microcephalia, neurologic abnormalities and intellectual disability [85]. Even moderate alcohol
consumption during pregnancy carries a risk of alterations in neurodevelopment, as well as malformations
and physical impairments. Early identification of chronic alcohol intake is essential for the establishment
of preventive measures to diminish adverse effects among newborns [86].
Many relatively recent studies in animal models, such as rats, mice and guinea pigs [87] have been
performed to determine the consequences of chronic prenatal exposure to ethanol. In these experimental
studies, alcohol-induced oxidative stress and mitochondrial dysfunction has been described in placental
tissue [88]. The increase in trophoblast apoptosis (associated with increased expression of pro-apoptotic
proteins and decreased antiapoptotic proteins) and the increase of oxidative stress and lipid peroxidation
related to gestational exposure to ethanol [88] indicate that mitochondria are the main organelle involved
in all these processes. It has been reported that neuronal abnormalities found in the fetal alcohol
syndrome could be due to initial damage during astrocyte development, and this syndrome has been
associated with a lower number of mitochondria and presenting altered morphology [89]. Despite all
these results from animal models, significant data on mitochondrial toxicity derived from in utero fetal
exposure in human pregnancies are remarkably lacking.
3.4. Mitochondrial Toxicity of Poisonous Gases
There are many asphyxiating and potentially lethal gases that produce molecular damage due to its
condition of mitochondrial hazards. Some of these toxic gas agents include nitric oxide (NO), cyanide
(CN), hydrogen sulphide (H
S) or carbon monoxide (CO), some of which are responsible for severe
intoxications which may induce rapid death. The severity of the symptoms and the appearance of late
sequelae depend on the intensity and duration of the exposure. Interestingly, all these toxic gases present
the same mitotoxic pathophysiologic mechanism of damage through the inhibition of MRC complex IV,
which is ultimately responsible for oxygen consumption and cell respiration [26,9092]. A consequent
increase in oxidative stress steady state levels has also been described [93]. Among these gases, the most
frequent intoxication is produced by CO, triggered by abnormal combustion of complex organic
compounds occurring in an atmosphere lacking oxygen. This exposure can be acute (punctual) or chronic
(additive). Indeed, a special case of CO intoxication is that which is characteristic of smokers because
CO is one of the thousands of toxic compounds present in tobacco smoke [94]. The association of
obstetric problems with mitochondrial toxicity derived from tobacco consumption during pregnancy has
been previously described in the section on Abuse drugs.
No studies were found on mitochondrial toxicity derived from exogenous NO, CN, H
S or CO toxic
gas exposure during pregnancy. However, a few studies did report the effects of NO and CO as
Int. J. Environ. Res. Public Health 2014, 11 9907
endogenous physiologic factors synthesized during pregnancy. Some experimental evidence support an
association of the increase of these chemical substances with the enhanced oxidative stress that takes
place during pregnancy arising from increased placental mitochondrial activity and production of ROS.
Myatt et al. reported that these ROS (NO, CO and peroxynitrite) have pronounced effects on placental
function promoting vascular reactivity and trophoblast proliferation and differentiation. The description
of an improved oxidative metabolism, increased endothelial NO synthase expression and NO production
in human placenta after combined aerobic and resistance exercise training during the second half of
pregnancy is also remarkable [95]. However, all these effects are produced by endogenous NO and CO
synthesized by placenta, rather than by the exogenous gases responsible for toxic insults.
The production of ROS is part of the physiologic responses necessary at certain windows in placental
development. However, excessive ROS production may occur in pathologic pregnancies, such as those
complicated by preeclampsia and/or IUGR, overpowering antioxidant defenses and promoting
deleterious outcomes [96]. We found no reports describing the molecular or clinical consequences of
external NO or CO poisoning during pregnancy, but a potential increase in ROS generation and adverse
obstetric outcome is plausible.
3.5. Chemical Substances such as Pesticides
Some pesticides (herbicides, insecticides or acaricides) can seriously damage the mitochondria.
These compounds may induce clinical symptoms of acute intoxication but usually produce clinical
manifestations after prolonged low-dose chronic exposure such as that produced by occupational
contact. At present, many neurodegenerative disorders, especially Parkinson’s disease, have been
associated with the toxic effect of certain chemical agents on neurons due to potential toxicant activity.
Different mechanisms causing damage to the mitochondria have been described in pesticides, but the
inhibition of MRC complex I enzymatic activity is one of the most common mitochondrial toxic
capacities described among the most frequently used compounds (rotenone, pyridaben, fenazaquin and
fenpyroximate), some of which increase ROS production (rotenone, pyridaben, paraquat) accompanied,
in some cases, by the consequent development of apoptosis (paraquat and glyophosphate) [97].
For instance, blood cholinesterases and tissue carboxylesterases (CE) are sensitive indicators of
exposure to environmental organophosphate pesticides (OP). In a study including healthy women living
on agricultural farms, the authors studied the impact of OP exposure on placental CE activity and lipid
composition during the pulverization and recess periods. Plasma and placental CE activity decreased in
the pulverization period, suggesting that these pesticides reached the placenta. The cardiolipin content
increased and the phosphatidylethanolamine content decreased in the light mitochondrial fraction [98],
suggesting that potential detrimental toxicity may affect fetal development.
Nonetheless, further studies are needed to assess the impact of pesticides on human pregnancies due
to frequent or even chronic exposure to these everyday compounds and the little information available
reporting potential adverse effects on fertility or pregnancy outcomes.
4. Discussion
Several studies have suggested that the mitochondria are critical for successful fertilization and fetal
development [14]. For instance, mitochondrial dysfunction has been associated with reproductive
Int. J. Environ. Res. Public Health 2014, 11 9908
outcome since their function influences the viability of both sperm and oocytes. Accordingly, a low
mtDNA content in both males [99,100] and females [4,44] has been related to infertility. In addition,
mutations in the mtDNA genome have also been described in spermatozoa with declined motility and
fertility [101].
In general, disorders of mitochondrial function in oocytes may cause reproductive failure.
Mitochondrial defects in oocytes can eventually lead to cell dysfunction and infertility and mitochondrial
content has been demonstrated to reflect oocyte viability and fertilization outcome [4]. Both Reynier
[100] and Santos [4] established an association between the mtDNA content and fertilization. The latter
study suggested that mtDNA content could be a marker of oocyte quality and fertility. Other studies
have suggested that a low mtDNA content is associated with the impaired oocyte quality observed in
ovarian insufficiency [102].
Accordingly, adequate mitochondrial and mtDNA content in both male and female gametes is
intrinsic for successful fertility. Nonetheless, once fertilization is achieved, mitochondrial function is
still essential for fetal development and a favorable obstetric outcome. Some studies have analyzed the
implication of mtDNA levels in fetal growth. Gemma et al. reported that newborns with abnormally low
and high birth weight present less mtDNA content in the umbilical cord [79,103]. More recently,
other authors corroborated these results in cord blood leucocytes of neonates with reduced body
mass [103,104], suggesting that appropriate mtDNA levels are essential for appropriate birth weight
development. Intrauterine growth restriction and pregnancy hypertensive disorders such as preeclampsia
associated with IUGR share a common placental phenotype called “placental insufficiency”, originating
early in pregnancy when the availability of high energy output is required. This period is characterized
by decidual trophoblast invasion and intense cellular growth, replication and differentiation. Since a
huge energetic production is required during gestation, the mitochondria may play a crucial role in this
process, being the main energetic producer in the cell.
Mitochondrial disturbances can arise from both inherited diseases and exposure to toxic substances.
Genetically inherited diseases can be suspected and avoided through preconceptional genetic counseling.
However, mitochondrial toxicities can be acquired by healthy pregnant women exposed to mitochondrial
toxic compounds during gestation, with consequences for affected newborns similar to those of
mitochondriopathies of genetic origin. Dozens of compounds in our everyday life are toxic for
mitochondria, including some found in daily clinical practice. A large number of studies have reported
the toxic adverse effects of these mitochondrial poisons in non-pregnant subjects. However, only a few
studies have analyzed the effects derived from in utero exposure. Indeed, there are very scarce data
regarding the use of antipsychotics, antibiotics, antidiabetics, anaesthetics, antimalarials or fungicides,
among others, during gestation.
It is unclear whether the lack of information related to these factors is related to the inability to undertake
designated studies (exclusively observational or case-reports are available) or if the mitochondrial toxicity
in pregnant women has minimal consequences on obstetric outcomes. On the contrary, the number of
studies reporting information about HIV, ARV and tobacco exposure during gestation was higher,
probably due to a larger number of pregnancies affected by such exposures.
The negative mitochondrial and clinical effects of ARV have been focused on HIV-human
pregnancies with some controversial results [45,50]. However, most studies associated ARV-derived
mitochondrial toxicity with significant mtDNA depletion and mitochondrial dysfunction in maternal,
Int. J. Environ. Res. Public Health 2014, 11 9909
fetal and/or placental tissues, usually demonstrating a strong, significant and positive correlation in
materno-fetal mitochondrial lesion. Antiretroviral drugs are able to cross the placental barrier. Our group
reached similar conclusions regarding the mitochondrial toxicity observed in smoking pregnant women:
newborns exposed to tobacco in utero showed a similar mitochondrial toxicity to that of their smoking
mothers [79]. Again, substances derived from tobacco which are toxic to the mitochondria (such as CO)
present transplacental activity and may reach the fetus in this crucial stage of development.
Transplacental mitochondrial toxicities have also been demonstrated in pesticide exposure [98], once
again demonstrating the strong relationship of materno-fetal toxicities.
The adverse clinical effects of these mitochondrial toxicities have been reported both in exposed
mothers and fetuses along gestation. Increased adverse obstetric outcomes are frequent in these
pregnancies. Maternal clinical and mitochondrial recovery is feasible once the toxic exposure is
discontinued (whenever possible). However, during fetal development a multitude of physiologic
responses take place in mitochondrially endangered fetuses to overcome the energetic imbalance and/or
oxidative and apoptotic insult. The homeostatic mechanisms responsible for fetal remodeling of the
adaptative response cannot be reversed once the fetuses are born and the toxic exposure is disrupted
(if possible). All this molecular and cell fetal remodeling derived from exposure to mitochondrial toxic
compounds in utero may have long term consequences of unknown severity.
There is currently no therapeutic option available for mitochondrial pathologies or for their potential
transmission. Selenium supplementation has been proposed as a protector mechanism of trophoblast
cells from oxidative stress [105]. However, to date, genetic counseling and preimplantacional diagnosis
are the best therapeutic options to avoid the transmission of mitochondrial diseases. Future IVF strategies
including the use of restriction enzymes to decrease the number of mutated mtDNA molecules in the
maternal oocyte or mitochondrial replacement techniques (through Spindel and Pronuclear Transfer)
may prevent the transmission of mitochondrial disease (in the former by using three reproductive cells;
the extra oocyte is necessary to provide healthy mitochondria) [106]. However, when these therapeutic
options become available they will probably be devoted to avoiding transmission of inherited
mitochondrial diseases. Nonetheless, despite having similar molecular and clinical consequences,
mitochondrial diseases acquired by toxic exposure to any mitochondrial poison, cannot, at present, be
treated or prevented.
Consequently, further studies are needed to determine the fetal and future neonatal consequences of
exposure to mitochondrial toxic agents in utero which are frequently present in our everyday life.
Currently, it is best to avoid exposure to all the above mentioned toxic mitochondrial hazards.
Nevertheless, to prevent damage, in case of therapeutic or accidental exposure, further research is
required to find compounds which are less harmful to the mitochondria and to establish or translate
biomarkers into clinical practice to follow mitochondrial lesions in pregnant women.
5. Conclusions
Mitochondrial toxicity derived from exposure to toxic agents can potentially involve much more
severe consequences in the context of pregnancy than in adulthood as they may condition fetal
remodeling, physiologic alterations and irreversible changes in the life of the developing individual.
Int. J. Environ. Res. Public Health 2014, 11 9910
Further studies are needed to elucidate the impact of mitochondrial toxic substances during the fertile
stage and especially during pregnancy in humans in order to understand the precise molecular
mechanisms leading to adverse clinical events.
As the current treatments are symptomatic and supportive rather than therapeutic, the prevention of
acquired mitochondrial diseases and exposure to mitochondrial toxicity is, to date, the best prophylactic
therapeutic option of choice.
Since prevention is not always possible in therapeutic or accidental exposures, there is the crucial
need to find substances which are less toxic to the mitochondria, to search for biomarkers which facilitate
monitoring during pregnancy and to assess the risk-benefit imbalance in cases of treatment prescription.
Indeed, some biomarkers have already been developed and should be applied to the clinical field.
This work was supported by Fundación para la Investigación y la Prevención del SIDA en España
[FIPSE 360745/09 and 360982/10]; Fundació Cellex, Fondo de Investigación Sanitaria [FIS 12/01199,
PI13/01738 and PI13/01455]; Suports a Grups de Recerca de la Generalitat de Catalunya
[SGR 2014/376] and CIBER de Enfermedades Raras (CIBERER, an initiative of ISCIII). We also wish
to thank the valuable help of our laboratory and clinician staff (Ester Tobias, Marc Catalan,
Ester Lozano, Francesc Cardellach and Josep Maria Grau), and Donna Pringle for language assistance.
Author Contributions
All authors have equally participated in the development of the work. However, specific contributions
were provided by each author, depending on their area of expertise. Constanza Morén as an expertise of
experimental research on mitochondrial toxicity in pediatric patients, has contributed to the bibliographic
research of mitochondrial toxicity data and the redaction of the review.
Sandra Hernández as a gynecologist and obstetric clinician, has contributed to the medical point of view
of the work. Mariona Guitart-Mampel as an expertise of laboratory research and mitochondrial
implication in obstetric outcomes, has contributed to the bibliographic research of experimental data of
the work. Glòria Garrabou as an expertise researcher of mitochondrial pathology, has contributed to the
design, writing and review of the work.
Conflicts of Interest
None of the authors has any financial, consultant, institutional and other relationship that might lead
to bias or a conflict of interest for the present manuscript.
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© 2014 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article
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... The mechanism of how the combined ARVs or their combination in the HAART therapy affect the reproductive system is still not well understood, but some studies have proposed that it may be through the sperm and oocyte mitochondrial DNA toxicity which can lead to changes in sperm parameters, absence of oocyte maturation and high rate of oocyte apoptosis (Pavili et al., 2010;Kushnir and Lewis 2011;Mor en et al., 2014;Hernandez et al., 2017). As mitochondrial DNA is inherited from the mother to the embryo; the consequences of a decrease in oocyte mitochondrial DNA due to toxicity, would be inhibition of oocyte maturation, decreased fertilization, embryo development delay or failure to get pregnant (Osellame et al., 2012;Mor en et al., 2014;Hernandez et al., 2017). ...
... The mechanism of how the combined ARVs or their combination in the HAART therapy affect the reproductive system is still not well understood, but some studies have proposed that it may be through the sperm and oocyte mitochondrial DNA toxicity which can lead to changes in sperm parameters, absence of oocyte maturation and high rate of oocyte apoptosis (Pavili et al., 2010;Kushnir and Lewis 2011;Mor en et al., 2014;Hernandez et al., 2017). As mitochondrial DNA is inherited from the mother to the embryo; the consequences of a decrease in oocyte mitochondrial DNA due to toxicity, would be inhibition of oocyte maturation, decreased fertilization, embryo development delay or failure to get pregnant (Osellame et al., 2012;Mor en et al., 2014;Hernandez et al., 2017). ...
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The burden of the human immunodeficiency virus and acquired immunodeficiency syndrome (HIV/AIDS) infection has transformed the African continent into a major consumer of antiretrovirals (ARVs) drugs. In addition to HIV burden, the African continent has also a high incidence of tuberculosis (TB) and has been experiencing recurring outbreaks of several other viral, bacterial, and parasitic epidemic diseases. The novel severe acute respiratory syndrome coronavirus 2 (SARS-COV-2 or Covid-19) pandemic outbreak is adding to the continent’s infectious diseases burden as experts are predicting that it will be here for a long time. One of the consequences of these infectious diseases is that antiviral and antibiotic compounds have become some of the most consumed pharmaceuticals on the continent. Many of these drugs have been frequently detected in surface waters across Africa. There is limited information available on the adverse effects of the mixtures of different types of pharmaceuticals in African aquatic environments on fish reproduction. The present study investigated the effects of the ARV drug nevirapine (NVP - 1.48 and 3.74 μg/L) and its mixture with the antibiotic sulfamethoxazole (3.68 μg/L) and trimethoprim (0.87 μg/L) on O. mossambicus gonads using histopathological endpoints as biomarkers. The fish (n = 52) were exposed for 30 days in a static renewal system. Female O. mossambicus exposed to nevirapine (3.74 μg/L) and to NVP – antibiotic mixture recorded higher ovary indices. Statistically significant differences were found in female ovary indices between the fish exposed to NVP (3.74 μg/L) and the control fish (p = 0.002) as well as between the fish exposed to the NVP - antibiotic mixture and the control fish (p = 0.009). The main observed histopathological changes in the ovaries were increased vitellogenic oocyte atresia and vacuolation of the interstitial tissue in the fish exposed to NVP - antibiotic mixture. It is evident that the presence of NVP - antibiotics mixture in water triggered the observed histopathology in female fish ovaries. The detected abnormal high rate of atretic oocytes could result in impaired fish reproduction.
... Mitochondria as a cellular organelle is responsible for cellular respiration and ATP production with a relatively small genome size of 16.5 Kb (Morén et al., 2014). The mitochondrial dysfunctions have been recognized in several human diseases including hereditary disorders (Chakrabarty et al., 2018). ...
... Previous studies have reported the role of mitochondrial function in pregnancy and fetal development (Bentov et al., 2011;Chappel, 2013) has paved the way to understand its role during pathophysiology of IUGR. It has long been recognized that effective mitochondrial activity is essential during pregnancy to provide sufficient energy and metabolites for the proper development of the embryo, a process which is required for the cell division, migration, and differentiation (Morén et al., 2014). In the present study, we examined the integrity of mitochondrial DNA (mtDNA) among the placental tissues to suggest its association with IUGR condition. ...
Intrauterine Growth Restriction (IUGR) is a common and significant complication that arises during pregnancy wherein the fetus fails to attain its full growth potential. Mitochondria being one of the primary sources of energy, plays an important role in placentation and fetal development. In IUGR pregnancy, increased oxidative stress due to inadequate oxygen and nutrient supply could possibly alter mitochondrial functions and homeostasis. In this study, we evaluated the biochemical and molecular changes in mitochondria as biosignature for early and better characterization of IUGR pregnancies. We identified significant increase in mtDNA copy number in both IUGR (p= 0.0001) and Small for Gestational Age (SGA) but healthy (p=0.0005) placental samples when compared to control. Whole mitochondrial genome sequencing identified novel mutations in both coding and non-coding regions of mtDNA in multiple IUGR placental samples. Sirtuin-3 (Sirt3) protein expression was significantly downregulated (p=0.027) in IUGR placenta but there was no significant difference in Nrf1 expression in IUGR when compared to control group. Our study provides an evidence for altered mitochondrial homeostasis and paves a way towards interrogating mitochondrial abnormalities in IUGR pregnancies.
... NRTIs are permeable to the placenta, and there are existing concerns about NRTIinduced mitochondrial toxicity in the placenta during pregnancy [21]. Efficient mitochondrial function is crucial to pregnancy and fetal development [22], and mitochondria toxicity during pregnancy could significantly alter the course of pregnancy and lead to adverse pregnancy outcomes, including fetal growth restriction. Human and animal studies have suggested that exposure to NRTIs during pregnancy can lead to mitochondrial toxicity in the offspring, although clinical findings of mitochondrial toxicity are infrequent [6,[23][24][25][26][27][28][29][30][31][32][33]. ...
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Nucleos(t)ide reverse transcriptase inhibitors (NRTIs) are the backbone of HIV antiretroviral therapy (ART). ART use in pregnancy has been associated with adverse birth outcomes, in part due to NRTI-induced mitochondrial toxicity. Direct comparison on the effects of commonly used dual-NRTI regimens on placental mitochondria toxicity in pregnancy is lacking. We compared zidovudine/lamivudine, abacavir/lamivudine, and tenofovir/emtricitabine using a mouse model and examined markers of placental mitochondrial function and oxidative stress. Zidovudine/lamivudine and abacavir/lamivudine were associated with lower fetal and placental weights compared to controls, whereas tenofovir/emtricitabine was associated with the least fetal and placental weight reduction, as well as lower resorption rates. Placental mitochondrial DNA content, as well as placental expression of cytochrome c-oxidase subunit-II, DNA polymerase gamma, and citrate synthase, was higher in tenofovir/emtricitabine-treated mice compared to other groups. Zidovudine/lamivudine-treated mice had elevated malondialdehyde levels (oxidative stress marker) compared to other groups and lower mRNA levels of manganese superoxide dismutase and peroxisome proliferator-activated receptor gamma coactivator 1-alpha in the placenta compared to tenofovir/emtricitabine-treated mice. We observed differences in effects between NRTI regimens on placental mitochondrial function and birth outcomes. Tenofovir/emtricitabine was associated with larger fetuses, increased mtDNA content, and higher expression of mitochondrial-specific antioxidant enzymes and mitochondrial biogenesis enzymes, whereas zidovudine/lamivudine was associated with markers of placental oxidative stress.
... Mitochondria play an essential role during gestation, and their correct functioning is fundamental for optimal pregnancy development and resolution [1], protecting against offspring alterations [2] and maternal pathologies [3]. Mitochondria are multifunctional organelles involved in stem cell differentiation, programmed cell death, stress response [4], intracellular calcium concentration control, ATP production [5,6], and toxic waste regulation [4]. ...
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An altered mitochondrial DNA copy number (mtDNAcn) at birth can be a marker of increased disease susceptibility later in life. Gestational exposure to acute stress, such as that derived from the earthquake experienced on 19 September 2017 in Mexico City, could be associated with changes in mtDNAcn at birth. Our study used data from the OBESO (Biochemical and Epigenetic Origins of Overweight and Obesity) perinatal cohort in Mexico City. We compared the mtDNAcn in the umbilical cord blood of 22 infants born before the earthquake, 24 infants whose mothers were pregnant at the time of the earthquake (exposed), and 37 who were conceived after the earthquake (post-earthquake). We quantified mtDNAcn by quantitative real-time polymerase chain reaction normalized with a nuclear gene. We used a linear model adjusted by maternal age, body mass index, socioeconomic status, perceived stress, and pregnancy comorbidities. Compared to non-exposed newborns (mean ± SD mtDNAcn: 0.740 ± 0.161), exposed and post-earthquake newborns (mtDNAcn: 0.899 ± 0.156 and 0.995 ± 0.169, respectively) had increased mtDNAcn, p = 0.001. The findings of this study point at mtDNAcn as a potential biological marker of acute stress and suggest that experiencing an earthquake during pregnancy or before gestation can have programing effects in the unborn child. Long-term follow-up of newborns to women who experience stress prenatally, particularly that derived from a natural disaster, is warranted.
... Recent studies have highlighted increased risk of intrahepatic cholestasis of pregnancy, 7 preterm birth, 8 low birth weight, 9 and mitochondrial toxicity and inflammation from HCV exposure in pregnancy, leading to adverse perinatal outcomes. 10 Antenatal HCV screening and treatment in pregnancy could cure maternal HCV and potentially avert vertical transmission and associated negative pregnancy and infant outcomes, and substantially advance the global HCV elimination targets. Although universal screening for HCV in pregnancy recommended in some countries, the extent to which it is being implemented is unclear and some countries, such as Pakistan, require out of pocket fees which may limit the uptake. ...
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Background: The risk of vertical transmission of hepatitis C virus (HCV) is ≈6%, and evidence suggests HCV negatively affects pregnancy and infant outcomes. Despite this, universal antenatal HCV screening is not available in most settings, and direct acting antivirals (DAA) are yet to be approved for use in pregnancy or breastfeeding period. Larger safety and efficacy trials are needed. At current there is limited understanding of the acceptability of routine HCV screening and use of DAAs in pregnancy but only among women in high HCV burden countries. Methods: We conducted a cross-sectional survey of pregnant or post-partum (<6 months since delivery) women attending antenatal clinics or maternity hospitals in Egypt, Pakistan and Ukraine. In Ukraine, this included one HIV clinic. Acceptability of free universal antenatal HCV screening and potential uptake of DAA treatment in the scenario of DAAs being approved for use in pregnancy was assessed. Results were stratified by HCV status and in Ukraine by HIV status. Descriptive statistics were used to explore differences in acceptability of treatment in pregnancy by country. Findings: Among 630 women (n=210 per country) who participated, the median age was 30 [interquartile range (IQR) 26, 34] years, 73% were pregnant and 27% postpartum, and 27% ever HCV antibody or PCR positive. 40% of women in Ukraine were living with HIV. Overall 93% of women supported free universal HCV screening in pregnancy, with no difference by country. 88% would take DAAs in pregnancy if approved for use: 92%, 98% and 73% among women in Egypt, Pakistan and Ukraine, respectively. Motivation for use of DAAs in pregnancy (to avert vertical transmission or for maternal HCV cure) varied by country, HCV status and HIV status (in Ukraine). No predictors for acceptability of DAAs were identified. Interpretation: Our survey across 3 high burden countries found very high acceptability of free universal HCV screening and DAAs if approved for use in pregnancy. Clinical trials to evaluate the safety and efficacy of DAAs during pregnancy and breastfeeding are urgently required.
... The mature oocyte contains large amounts of mitochondria accounting for approximately 23% of its volume [23]. It is the mature oocyte that provides with the mitochondrial cargo for the embryo and although the spermatozoa do not provide with mitochondria, these organelles are important for sperm motility and male fertility [24]. After implantation, the blastocyst experience a significant metabolic shift with enhanced reliance on glycolysis for ATP production [25]. ...
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Pregnancy is a challenging physiological process that involves maternal adaptations to the increasing energetics demands imposed by the growing conceptus. Failure to adapt to these requirements may result in serious health complications for the mother and the baby. The mitochondria are biosynthetic and energy-producing organelles supporting the augmented energetic demands of pregnancy. Evidence suggests that placental mitochondria display a dynamic phenotype through gestation. At early stages of pregnancy placental mitochondria are mainly responsible for the generation of metabolic intermediates and reactive oxygen species (ROS), while at later stages of gestation, the placental mitochondria exhibit high rates of oxygen consumption. This review describes the metabolic fingerprint of the placental mitochondria at different stages of pregnancy and summarises key signs of mitochondrial dysfunction in pathological pregnancy conditions, including preeclampsia, gestational diabetes and intrauterine growth restriction (IUGR). So far, the effects of placental-driven metabolic changes governing the metabolic adaptations occurring in different maternal tissues in both, healthy and pathological pregnancies, remain to be uncovered. Understanding the function and molecular aspects of the adaptations occurring in placental and maternal tissue’s mitochondria will unveil potential targets for further therapeutic exploration that could address pregnancy-related disorders. Targeting mitochondrial metabolism is an emerging approach for regulating mitochondrial bioenergetics. This review will also describe the potential therapeutic use of compounds with a recognised effect on mitochondria, for the management of preeclampsia.
The herbicide market is growing rapidly, as weed control is a significant challenge in agriculture. Many studies have reported the toxicity of herbicides to non-target organisms. Dinitramine is a dinitroaniline herbicide that is particularly toxic to aquatic organisms. However, little is known about the effects of dinitramine on the female reproductive system. Therefore, in the present study, we utilized porcine trophectoderm (pTr) cells and porcine endometrial luminal epithelial (pLE) cells to verify the reproductive toxicity of dinitramine. Dinitramine reduced the viability of both cell types, by triggering cell cycle arrest, especially at the sub-G1 phase, and increasing apoptosis, inhibiting DNA replication. Dinitramine disrupted intracellular calcium homeostasis and induced oxidative stress by producing reactive oxygen species, leading to the loss of mitochondrial membrane potential and alteration of mitochondrial respiration. Mitogen-activated protein kinase pathways were altered, and migration decreased in pTr and pLE cells after dinitramine treatment; the expression of pregnancy-related genes in these cells was decreased. Thus, dinitramine reduced the viability and migratory capacity of both cell types, and this could interrupt the early stages of pregnancy.
Alcohol is one of the most consumed drugs in the world, even during pregnancy. Its use is a risk factor for developing adverse outcomes, e.g. fetal death, miscarriage, fetal growth restriction, and premature birth, also resulting in fetal alcohol spectrum disorders. Ethanol metabolism induces an oxidative environment that promotes the oxidation of lipids and proteins, triggers DNA damage, and advocates mitochondrial dysfunction, all of them leading to apoptosis and cellular injury. Several organs are altered due to this harmful behavior, the brain being one of the most affected. Throughout pregnancy, the human placenta is one of the most important organs for women's health and fetal development, as it secretes numerous hormones necessary for a suitable intrauterine environment. However, our understanding of the human placenta is very limited and even more restricted is the knowledge of the impact of toxic substances in its development and fetal growth. So, could ethanol consumption during this period have wounding effects in the placenta, compromising proper fetal organ development? Several studies have demonstrated that alcohol impairs various signaling cascades within G protein-coupled receptors and tyrosine kinase receptors, mainly through its action on insulin and insulin-like growth factor 1 (IGF-1) signaling pathway. This last cascade is involved in cell proliferation, migration, and differentiation and in placentation. This review tries to examine the current knowledge and gaps in our existing understanding of the ethanol effects in insulin/IGFs signaling pathway, which can explain the mechanism to elucidate the adverse actions of ethanol in the maternal-fetal interface of mammals.
Mitochondria fuel placental activity, with mitochondrial dysfunction implicated in several perinatal complications. We investigated placental mtDNA mutational load using NextGen sequencing in relation to birthweight and gestational length among 358 mother-newborn pairs. We found that higher heteroplasmy, especially in the hypervariable displacement loop region, was associated with shorter gestational length. Results were similar among male and female pregnancies, but stronger in magnitude among females. With regard to growth, we observed that higher mutational load was associated with lower birthweight-for-gestational age (BWGA) among females, but higher BWGA among males. These findings support potential sex-differential fetal biological strategies for coping with increased heteroplasmies.
Both obesity and gestational diabetes mellitus (GDM) lead to poor maternal and fetal outcomes, including pregnancy complications, fetal growth issues, stillbirth, and developmental programming of adult-onset disease in the offspring. Increased placental oxidative/nitrative stress and reduced placental (trophoblast) mitochondrial respiration occur in association with the altered maternal metabolic milieu of obesity and GDM. The effect is particularly evident when the fetus is male, suggesting a sexually dimorphic influence on the placenta. In addition, obesity and GDM are associated with inflexibility in trophoblast, limiting the ability to switch between usage of glucose, fatty acids, and glutamine as substrates for oxidative phosphorylation, again in a sexually dimorphic manner. Here we review mechanisms underlying placental mitochondrial dysfunction: its relationship to maternal and fetal outcomes and the influence of fetal sex. Prevention of placental oxidative stress and mitochondrial dysfunction may improve pregnancy outcomes. We outline pathways to ameliorate deficient mitochondrial respiration, particularly the benefits and pitfalls of mitochondria-targeted antioxidants.
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Alcohol consumption during pregnancy, even when moderate, implies a risk of impaired neurodevelopment, physical impairments and malformations. Its early identification is essential for establishing preventive measures to diminish disabilities among newborns. To determine the frequency of consumption of substance use in pregnant women, we have used the techniques of gas chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry to detect drugs and markers of chronic consumption of alcohol in meconium. We performed a prospective study during a period of 10 months among 110 infants in our hospital, assessing anthropometry, neuromuscular development and determination of toxic substances in urine and meconium. Furthermore, meconium analysis identified fatty acid ethyl esters (FAEEs) and ethyl glucuronide (Etg). We also conducted a survey regarding the obstetric history, toxic habits, and employment status of the mothers. According to early detection markers analyzed in meconium (FAEE >1000 ng/g and/or Etg >50 ng/g meconium), 34.65% of pregnant women consumed alcohol during pregnancy, and 17% were positive for both markers. Within the positive cases, 50% of those exceeding a FAEE's value of 5000 ng/g in meconium had low birth-weight children. Only 5/110 mothers (4.5%) admitted to occasional alcohol consumption during pregnancy. Nobody admitted to frequent intake. The cocaine test was positive in three cases; two of them were positive for alcohol as well. As expected, many screening devices do not accurately capture use during pregnancy and supplemental methods such as meconium analysis of biomarkers of chronic alcohol consumption may be warranted.
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Mitochondrial toxicity has been recently suggested to be the underlying mechanism of long-term linezolid-associated toxicity in patients with 16S rRNA genetic polymorphisms. Here, we report for the first time two cases of lactic acidosis due to long-term linezolid exposure in liver transplant recipients who presented an A2706G mitochondrial DNA polymorphism.
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The underlying mechanism of the central nervous system (CNS) injury after acute carbon monoxide (CO) poisoning is interlaced with multiple factors including apoptosis, abnormal inflammatory responses, hypoxia, and ischemia/reperfusion-like problems. One of the current hypotheses with regard to the molecular mechanism of CO poisoning is the oxidative injury induced by reactive oxygen species, free radicals, and neuronal nitric oxide. Up to now, the relevant mechanism of this injury remains poorly understood. The weakening of antioxidant systems and the increase of lipid peroxidation in the CNS have been implicated, however. Accordingly, in this review, we will highlight the relationship between oxidative stress and CO poisoning from the perspective of forensic toxicology and molecular toxicology.
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Intrauterine growth restriction (IUGR) and pregnancy hypertensive disorders such as preeclampsia (PE) associated with IUGR share a common placental phenotype called "placental insufficiency" originating in early gestation, when high availability of energy is required. Here, we assess mitochondrial content and the expression and activity of respiratory chain complexes (RCC) in placental cells of these pathologies. We measured mitochondrial DNA (mtDNA) and Nuclear Respiratory Factor 1 (NRF1) expression in placental tissue and cytotrophoblast cells, gene and protein expressions of RCC (Real Time PCR and Western Blotting) and their oxygen consumption, using the innovative technique of High Resolution Respirometry. We analyzed eight IUGR, six PE and eight uncomplicated human pregnancies delivering by elective cesarean section. We found lower mRNA levels of complex II, III and IV in IUGR cytotrophoblast cells, but no differences at the protein level, suggesting a post-transcriptional compensatory regulation. mtDNA was increased in IUGR placentas. Both mtDNA and NRF1 expression were instead significantly lower in their isolated cytotrophoblast cells. Finally, cytotrophoblast RCC activity was significantly increased in placentas of IUGR fetuses. No significant differences were found in PE placentas. This study sheds genuine new data into the complex physiology of placental oxygenation in IUGR fetuses. The higher mitochondrial content in IUGR placental tissue is reversed in cytotrophoblast cells, which instead present higher mitochondrial functionality. This suggests different mitochondrial content and activity depending on the placental cell lineage. Increased placental oxygen consumption might represent a limiting step in fetal growth restriction, preventing adequate oxygen delivery to the fetus.
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.
The exchange of nuclear genetic material between oocytes and embryos offers a novel reproductive option for the prevention of inherited mitochondrial diseases. Mitochondrial dysfunction has been recognized as a significant cause of a number of serious multiorgan diseases. Tissues with a high metabolic demand, such as brain, heart, muscle, and central nervous system, are often affected. Mitochondrial disease can be due to mutations in mitochondrial DNA or in nuclear genes involved in mitochondrial function. There is no curative treatment for patients with mitochondrial disease. Given the lack of treatments and the limitations of prenatal and preimplantation diagnosis, attention has focused on prevention of transmission of mitochondrial disease through germline gene replacement therapy. Because mitochondrial DNA is strictly maternally inherited, two approaches have been proposed. In the first, the nuclear genome from the pronuclear stage zygote of an affected woman is transferred to an enucleated donor zygote. A second technique involves transfer of the metaphase II spindle from the unfertilized oocyte of an affected woman to an enucleated donor oocyte. Our group recently reported successful spindle transfer between human oocytes, resulting in blastocyst development and embryonic stem cell derivation, with very low levels of heteroplasmy. In this review we summarize these novel assisted reproductive techniques and their use to prevent transmission of mitochondrial disorders. The promises and challenges are discussed, focusing on their potential clinical application.