Exploiting sweet relief for preeclampsia by targeting autophagy-lysosomal machinery and proteinopathy.

The etiology of preeclampsia (PE), a severe complication of pregnancy with several clinical manifestations and a high incidence of maternal and fetal morbidity and mortality, remains unclear. This issue is a major hurdle for effective treatment strategies. We recently demonstrated that PE exhibits an Alzheimer-like etiology of impaired autophagy and proteinopathy in the placenta. Targeting of these pathological pathways may be a novel therapeutic strategy for PE. Stimulation of autophagy with the natural disaccharide trehalose and its lacto analog lactotrehalose in hypoxia-exposed primary human trophoblasts restored autophagy, inhibited the accumulation of toxic protein aggregates, and restored the ultrastructural features of autophagosomes and autolysosomes. Importantly, trehalose and lactotrehalose inhibited the onset of PE-like features in a humanized mouse model by normalizing autophagy and inhibiting protein aggregation in the placenta. These disaccharides restored the autophagy-lysosomal biogenesis machinery by increasing nuclear translocation of the master transcriptional regulator TFEB. RNA-seq analysis of the placentas of mice with PE indicated the normalization of the PE-associated transcriptome profile in response to trehalose and lactotrehalose. In summary, our results provide a novel molecular rationale for impaired autophagy and proteinopathy in patients with PE and identify treatment with trehalose and its lacto analog as promising therapeutic options for this severe pregnancy complication.

Cis P-tau is a central circulating and placental etiologic driver and therapeutic target of preeclampsia.

Preeclampsia (PE) is the leading cause of maternal and fetal mortality globally and may trigger dementia later in life in mothers and their offspring. However, the etiological drivers remain elusive. Cis P-tau is an early etiological driver and blood biomarker in pre-clinical Alzheimer's and after vascular or traumatic brain injury, which can be targeted by stereo-specific antibody, with clinical trials ongoing. Here we find significant cis P-tau in the placenta and serum of PE patients, and in primary human trophoblasts exposed to hypoxia or sera from PE patients due to Pin1 inactivation. Depletion of cis P-tau from PE patient sera by the antibody prevents their ability to disrupt trophoblast invasion and endovascular activity and to cause the PE-like pathological and clinical features in pregnant humanized tau mice. Our studies uncover that cis P-tau is a central circulating etiological driver and its stereo-specific antibody is valuable for early PE diagnosis and treatment.

Gestational Age-Dependent Regulation of Transthyretin in Mice during Pregnancy.

Our prior studies have shown that protein misfolding and aggregation in the placenta are linked to the development of preeclampsia, a severe pregnancy complication. We identified transthyretin (TTR) as a key component of the aggregated protein complex. However, the regulation of native TTR in normal pregnancy remains unclear. In this study, we found that pregnant mice exhibited a remarkable and progressive decline in serum TTR levels through gestational day (gd) 12-14, followed by an increase in late pregnancy and postpartum. Meanwhile, serum albumin levels showed a modest but statistically significant increase throughout gestation. TTR protein and mRNA levels in the liver, a primary source of circulating TTR, mirrored the changes observed in serum TTR levels during gestation. Intriguingly, a similar pattern of TTR alteration was also observed in the serum of pregnant women and pregnant interleukin-10-knockout (IL-10-/-) mice with high inflammation background. In non-pregnant IL-10-/- mice, serum TTR levels were significantly lower than those in age-matched wild-type mice. Administration of IL-10 to non-pregnant IL-10-/- mice restored their serum TTR levels. Notably, dysregulation of TTR resulted in fewer implantation units, lower fetal weight, and smaller litter sizes in human TTR-overexpressing transgenic mice. Thus, TTR may play a pivotal role as a crucial regulator in normal pregnancy, and inflammation during pregnancy may contribute to the downregulation of serum TTR presence.

The Role of Autophagy in the Female Reproduction System: For Beginners to Experts in This Field.

Autophagy is a fundamental process involved in regulating cellular homeostasis. Autophagy has been classically discovered as a cellular process that degrades cytoplasmic components non-selectively to produce energy. Over the past few decades, this process has been shown to work in energy production, as well as in the reduction of excessive proteins, damaged organelles, and membrane trafficking. It contributes to many human diseases, such as neurodegenerative diseases, carcinogenesis, diabetes mellitus, development, longevity, and reproduction. In this review, we provide important information for interpreting results related to autophagic experiments and present the role of autophagy in this field.

Recent insight into autophagy and immunity at the maternal-fetal interface.

Autophagy is a lysosomal degradation pathway that supports metabolic adaptation and energy cycling. It is essential for cell homeostasis, differentiation, development, and survival. Recent studies have shown that autophagy could influence immune responses by regulating immune cell functions. Reciprocally, immune cells strongly influence autophagy. Immune cells at the maternal-fetal interface are thought to play essential roles in pregnancy. Here, we review the induction of autophagy at the maternal-fetal interface and its role in decidualization and placental development. Additionally, we emphasize the role of autophagy in the immune microenvironment at the maternal-fetal interface, including innate immunity, adaptive immunity, and immune tolerance molecules. It also suggests new research directions and prospects.

Chloroquine is a safe autophagy inhibitor for sustaining the expression of antioxidant enzymes in trophoblasts.

Inhibition of autophagy contributes to the pathophysiology of preeclampsia. Although chloroquine (CHQ) is an autophagy inhibitor, it can reduce the occurrence of preeclampsia in women with systemic lupus erythematosus. To clarify this important clinical question, this study aimed to address the safety of CHQ in trophoblast cells from the viewpoint of homeostasis, in which the anti-oxidative stress (OS) response and autophagy are involved. We used Western blotting to evaluate the protein levels in the trophoblast cells. The expression levels of heme oxygenase-1 (HO-1), an anti-OS enzyme, mediate resistance to OS induced by hydrogen peroxide (H2O2) in trophoblast cell lines. Among the autophagy modulators, bafilomycin A1 (BAF), an autophagy inhibitor, but not autophagy activators, suppressed HO-1 expression in BeWo cells; CHQ did not suppress HO-1 expression in BeWo cells. To clarify the role of autophagy in HO-1 induction, we observed no difference in HO-1 induction by H2O2 between autophagy-normal and autophagy-deficient cells. As for the mechanism of HO-1 induction by OS, BAF suppressed HO-1 induction by downregulating the expression of neighbor of BRCA1 gene 1 (NBR1) in the selective p62-NBR1-nuclear factor erythroid 2-related factor 2 (Nrf2) autophagy pathway. CHQ did not inhibit HO-1 expression by sustaining NBR1 expression in human villous tissues compared to BAF treatment. In conclusion, CHQ is a safer medicine than BAF for sustaining NBR1, which resist against OS in trophoblasts by connecting selective autophagy and the anti-OS response.

Hypoxia-Reoxygenation Impairs Autophagy-Lysosomal Machinery in Primary Human Trophoblasts Mimicking Placental Pathology of Early-Onset Preeclampsia.

We have previously described that placental activation of autophagy is a central feature of normal pregnancy, whereas autophagy is impaired in preeclampsia (PE). Here, we show that hypoxia-reoxygenation (H/R) treatment dysregulates key molecules that maintain autophagy-lysosomal flux in primary human trophoblasts (PHTs). Ultrastructural analysis using transmission electron microscopy reveals a significant reduction in autophagosomes and autolysosomes in H/R-exposed PHTs. H/R-induced accumulation of protein aggregates follows a similar pattern that occurs in PHTs treated with a lysosomal disruptor, chloroquine. Importantly, the placenta from early-onset PE deliveries exhibits the same features as seen in H/R-treated PHTs. Taken together, our results indicate that H/R disrupts autophagic machinery in PHTs and that impaired autophagy in the placenta from early-onset PE deliveries mimics the events in H/R-treated PHTs. Notably, assessment of key regulators at each stage of autophagic processes, especially lysosomal integrity, and verification of autophagic ultrastructure are essential for an accurate evaluation of autophagy activity in human trophoblasts and placental tissue from PE deliveries.

Evidence From Human Placenta, Endoplasmic Reticulum-Stressed Trophoblasts, and Transgenic Mice Links Transthyretin Proteinopathy to Preeclampsia.

BACKGROUND: We have demonstrated that protein aggregation plays a pivotal role in the pathophysiology of preeclampsia and identified several aggregated proteins in the circulation of preeclampsia patients, the most prominent of which is the serum protein TTR (transthyretin). However, the mechanisms that underlie protein aggregation remain poorly addressed. METHODS: We examined TTR aggregates in hypoxia/reoxygenation-exposed primary human trophoblasts (PHTs) and the preeclampsia placenta using complementary approaches, including a novel protein aggregate detection assay. Mechanistic analysis was performed in hypoxia/reoxygenation-exposed PHTs and Ttr transgenic mice overexpressing transgene-encoded wild-type human TTR or Ttr-/- mice. High-resolution ultrasound analysis was used to measure placental blood flow in pregnant mice. RESULTS: TTR aggregation was inducible in PHTs and the TCL-1 trophoblast cell line by endoplasmic reticulum stress inducers or autophagy-lysosomal disruptors. PHTs exposed to hypoxia/reoxygenation showed increased intracellular BiP (binding immunoglobulin protein), phosphorylated IRE1α (inositol-requiring enzyme-1α), PDI (protein disulfide isomerase), and Ero-1, all markers of the unfolded protein response, and the apoptosis mediator caspase-3. Blockade of IRE1α inhibited hypoxia/reoxygenation-induced upregulation of Ero-1 in PHTs. Excessive unfolded protein response activation was observed in the early-onset preeclampsia placenta. Importantly, pregnant human TTR mice displayed aggregated TTR in the junctional zone of the placenta and severe preeclampsia-like features. High-resolution ultrasound analysis revealed low blood flow in uterine and umbilical arteries in human TTR mice compared with control mice. However, Ttr-/- mice did not show any pregnancy-associated abnormalities. CONCLUSIONS: These observations in the preeclampsia placenta, cultured trophoblasts, and Ttr transgenic mice indicate that TTR aggregation is an important causal contributor to preeclampsia pathophysiology.

Trophoblast-derived Lactic Acid Orchestrates Decidual Macrophage Differentiation via SRC/LDHA Signaling in Early Pregnancy.

Lactic acid (LA) metabolism in the tumor microenvironment contributes to the establishment and maintenance of immune tolerance. This pathway is characterized in tumor associated macrophages. However, the role and pathway of LA metabolism at maternal-fetal interface during early pregnancy, especially in decidual macrophage differentiation, are still unclear. Herein, for the first time, we discovered that LA can trigger either M2 or M1 macrophage polarization via oxidative phosphorylation and glycolysis regulation under normoxia or hypoxia, respectively. Also, LA metabolism played a vital role in decidual macrophages-mediated recurrent pregnancy loss (RPL), through HIF-1α/SRC/LDHA pathway. Moreover, blockade of LA intake with AZD3965 (MCT-1 inhibitor) could rescue pregnancy in an abortion-prone mouse model, suggesting a potential therapeutic target in RPL. Collectively, the present study identifies the previously unknown functions of LA metabolism in the differentiation of decidual macrophages in early normal pregnancy and RPL, and provides a potential therapeutic strategy in RPL by manipulating decidual macrophages' functions through LA metabolic pathway.

Etiological Value of Sterile Inflammation in Preeclampsia: Is It a Non-Infectious Pregnancy Complication?

Understanding of sterile inflammation and its associated biological triggers and diseases is still at the elementary stage. This becomes more warranted in cases where infections are not associated with the pathology. Detrimental effects of bacterial and viral infections on the immune responses at the maternal-fetal interface as well as pregnancy outcomes have been well documented. However, an infection-induced etiology is not thought to be a major contributing component to severe pregnancy complications such as preeclampsia (PE) and gestational diabetes. How is then an inflammatory signal thought to be associated with these pregnancy complications? It is not clear what type of inflammation is involved in the onset of PE-like features. We opine that sterile inflammation regulated by the inflammasome-gasdermins-caspase-1 axis is a contributory factor to the onset of PE. We hypothesize that increased production and release of damage-associated molecular patterns (DAMPs) or Alarmins such as high-mobility group box1 (HMGB1), cell-free fetal DNA, uric acid, the NOD-like receptor pyrin-containing receptor 3 (NLRP3) inflammasome, IL-1ß and IL-18 occur in the PE placenta. Some of these molecules have already been observed in the placenta from women with PE. Mechanistically, emerging evidence has demonstrated that excessive placental endoplasmic reticulum (ER) stress, impaired autophagy and gasdermine D (GSDMD)-mediated intrinsic pyroptosis are key events that contribute to systemic sterile inflammation in patients with PE, especially early-onset PE (e-PE). In this review, we highlight the advances on the roles of sterile inflammation and inflammatory signaling cascades involving ER stress, autophagy deficiency and pyroptosis in PE pathophysiology. Deciphering the mechanisms underlying these inflammatory pathways may provide potential diagnostic biomarkers and facilitate the development of therapeutic strategies to treat this devastating disease.

Novel blood test for early biomarkers of preeclampsia and Alzheimer's disease.

A non-invasive and sensitive blood test has long been a goal for early stage disease diagnosis and treatment for Alzheimer's disease (AD) and other proteinopathy diseases. We previously reported that preeclampsia (PE), a severe pregnancy complication, is another proteinopathy disorder with impaired autophagy. We hypothesized that induced autophagy deficiency would promote accumulation of pathologic protein aggregates. Here, we describe a novel, sensitive assay that detects serum protein aggregates from patients with PE (n = 33 early onset and 33 late onset) and gestational age-matched controls (n = 77) as well as AD in both dementia and prodromal mild cognitive impairment (MCI, n = 24) stages with age-matched controls (n = 19). The assay employs exposure of genetically engineered, autophagy-deficient human trophoblasts (ADTs) to serum from patients. The aggregated protein complexes and their individual components, including transthyretin, amyloid ß-42, α-synuclein, and phosphorylated tau231, can be detected and quantified by co-staining with ProteoStat, a rotor dye with affinity to aggregated proteins, and respective antibodies. Detection of protein aggregates in ADTs was not dependent on transcriptional upregulation of these biomarkers. The ROC curve analysis validated the robustness of the assay for its specificity and sensitivity (PE; AUC: 1, CI: 0.949-1.00; AD; AUC: 0.986, CI: 0.832-1.00). In conclusion, we have developed a novel, noninvasive diagnostic and predictive assay for AD, MCI and PE.

Aggrephagy Deficiency in the Placenta: A New Pathogenesis of Preeclampsia.

Aggrephagy is defined as the selective degradation of aggregated proteins by autophagosomes. Protein aggregation in organs and cells has been highlighted as a cause of multiple diseases, including neurodegenerative diseases, cardiac failure, and renal failure. Aggregates could pose a hazard for cell survival. Cells exhibit three main mechanisms against the accumulation of aggregates: protein refolding by upregulation of chaperones, reduction of protein overload by translational inhibition, and protein degradation by the ubiquitin-proteasome and autophagy-lysosome systems. Deletion of autophagy-related genes reportedly contributes to intracellular protein aggregation in vivo. Some proteins recognized in aggregates in preeclamptic placentas include those involved in neurodegenerative diseases. As aggregates are derived both intracellularly and extracellularly, special endocytosis for extracellular aggregates also employs the autophagy machinery. In this review, we discuss how the deficiency of aggrephagy and/or macroautophagy leads to poor placentation, resulting in preeclampsia or fetal growth restriction.

Molecular and immunological developments in placentas.

Cytotrophoblasts differentiate in two directions during early placentation: syncytiotrophoblasts (STBs) and extravillous trophoblasts (EVTs). STBs face maternal immune cells in placentas, and EVTs, which invade the decidua and uterine myometrium, face the cells in the uterus. This situation, in which trophoblasts come into contact with maternal immune cells, is known as the maternal-fetal interface. Despite fetuses and fetus-derived trophoblast cells being of the semi-allogeneic conceptus, fetuses and placentas are not rejected by the maternal immune system because of maternal-fetal tolerance. The acquired tolerance develops during normal placentation, resulting in normal fetal development in humans. In this review, we introduce placental development from the viewpoint of molecular biology. In addition, we discuss how the disruption of placental development could lead to complications in pregnancy, such as hypertensive disorder of pregnancy, fetal growth restriction, or miscarriage.

Placental extracellular vesicles and pre-eclampsia.

Pre-eclampsia is a hypertensive disease of pregnancy characterized by new-onset hypertension, with either proteinuria and/or organ dysfunction. Pre-eclampsia is a leading cause of maternal morbidity and mortality; however, the underlying cellular and molecular mechanisms are not well understood. There is consensus that the underlying mechanism(s) resulting in pre-eclampsia is centered around abnormal placentation, inadequate spiral-artery remodeling, and deficiency in trophoblast invasion, resulting in impaired maternal blood flow to the placenta and a release of signals and/or inflammatory mediators into maternal circulation triggering the systemic manifestations of pre-eclampsia. ER stress, resulting in impaired autophagy and placental release of aggregated proteins, may also confer systemic stress to maternal organs in pre-eclampsia. Extracellular vesicles (EVs), lipid-bilayer enclosed structures containing macromolecules including proteins, miRNA, and other important nucleotides, have been suggested to play an important role in this maternal-fetal communication. Circulating EVs are present in greater quantity in the plasma of pre-eclampsia subjects compared to normal pregnancy, and the placental derived EVs have been shown to have altered protein and RNA cargo. In this review, we will focus on EVs and their role in pre-eclampsia, specifically their role in immune responses, inflammation, altered angiogenesis, and endothelial dysfunction.

Placental autophagy failure: A risk factor for preeclampsia.

Hypertensive disorders of pregnancy, including preeclampsia, directly affect maternal and perinatal morbidity and mortality. As the pathophysiology of preeclampsia is multi-factorial and has been studied using different approaches, we have demonstrated that impaired autophagy is an intertwined risk factor for preeclampsia. This concept has been verified in both in vitro and in vivo experiments. Autophagy is primarily involved in maintaining cellular homeostasis, and in immune regulation, longevity, cytokines secretion and a variety of other biological functions. Here, we review the role of autophagy in normal embryogenesis and placentation. Once placental autophagy is impaired by metabolic stress such as hypoxia, endoplasmic reticulum stress or starvation, placental development could be disrupted, resulting in functional maladaptations at the maternal-fetal interface. These malfunctions may result in fetal growth restriction or preeclampsia.

Disruption of Placental Homeostasis Leads to Preeclampsia.

Placental homeostasis is directly linked to fetal well-being and normal fetal growth. Placentas are sensitive to various environmental stressors, including hypoxia, endoplasmic reticulum stress, and oxidative stress. Once placental homeostasis is disrupted, the placenta may rebel against the mother and fetus. Autophagy is an evolutionally conservative mechanism for the maintenance of cellular and organic homeostasis. Evidence suggests that autophagy plays a crucial role throughout pregnancy, including fertilization, placentation, and delivery in human and mouse models. This study reviews the available literature discussing the role of autophagy in preeclampsia.

Evidence for lysosomal biogenesis proteome defect and impaired autophagy in preeclampsia.

The etiology of preeclampsia (PE), a serious pregnancy complication, remains an enigma. We have demonstrated that proteinopathy, a pathologic feature of neurodegenerative diseases, is a key observation in the placenta and serum from PE patients. We hypothesize that the macroautophagy/autophagy machinery that mediates degradation of aggregated proteins and damaged organelles is impaired in PE. Here, we show that TFEB (transcription factor EB), a master transcriptional regulator of lysosomal biogenesis, and its regulated proteins, LAMP1, LAMP2, and CTSD (cathepsin D), were dysregulated in the placenta from early and late onset PE deliveries. Primary human trophoblasts and immortalized extravillous trophoblasts (EVTs) showed reduced TFEB expression and nuclear translocation as well as lysosomal protein content in response to hypoxia. Hypoxia-exposed trophoblasts also showed decreased PPP3/calcineurin phosphatase activity and increased XPO1/CRM1 (exportin 1), events that inhibit TFEB nuclear translocation. These proteins were also dysregulated in the PE placenta. These results are supported by observed lysosomal ultrastructural defects with decreased number of autolysosomes in hypoxia-treated primary human trophoblasts. Autophagy-deficient human EVTs exhibited poor TFEB nuclear translocation, reduced lysosomal protein expression and function, and increased MTORC1 activity. Sera from PE patients induced these features and protein aggregation in EVTs. Importantly, trophoblast-specific conditional atg7 knockout mice exhibited reduced TFEB expression with increased deposition of protein aggregates in the placenta. These results provide compelling evidence for a regulatory link between accumulation of protein aggregates and TFEB-mediated impaired lysosomal biogenesis and autophagy in the placenta of PE patients. Abbreviation:atg7: autophagy related 7; CTSD: cathepsin D; ER: endoplasmic reticulum; EVTs: extravillous trophoblasts; KRT7: keratin 7; LAMP1: lysosomal associated membrane protein 1; LAMP2: lysosomal associated membrane protein 2; mSt: mStrawberry; MTORC1: mechanistic target of rapamycin complex 1; NP: normal pregnancy; NPS: normal pregnancy serum; PE: preeclampsia; PES: preeclampsia serum; p-RPS6KB: phosphorylated ribosomal protein S6 kinase B1; SQSTM1/p62: sequestosome 1; TEM: transmission electron microscopy; TFEB: transcription factor EB; XPO1/CRM1: exportin 1.

Pyroptosis is a critical inflammatory pathway in the placenta from early onset preeclampsia and in human trophoblasts exposed to hypoxia and endoplasmic reticulum stressors.

Systemic manifestation of preeclampsia (PE) is associated with circulating factors, including inflammatory cytokines and damage-associated molecular patterns (DAMPs), or alarmins. However, it is unclear whether the placenta directly contributes to the increased levels of these inflammatory triggers. Here, we demonstrate that pyroptosis, a unique inflammatory cell death pathway, occurs in the placenta predominantly from early onset PE, as evidenced by elevated levels of active caspase-1 and its substrate or cleaved products, gasdermin D (GSDMD), IL-1ß, and IL-18. Using cellular models mimicking pathophysiological conditions (e.g., autophagy deficiency, hypoxia, and endoplasmic reticulum (ER) stress), we observed that pyroptosis could be induced in autophagy-deficient human trophoblasts treated with sera from PE patients as well as in primary human trophoblasts exposed to hypoxia. Exposure to hypoxia elicits excessive unfolded protein response (UPR) and ER stress and activation of the NOD-like receptor pyrin-containing 3 (NLRP3) inflammasome in primary human trophoblasts. Thioredoxin-interacting protein (TXNIP), a marker for hyperactivated UPR and a crucial signaling molecule linked to NLRP3 inflammasome activation, is significantly increased in hypoxia-treated trophoblasts. No evidence was observed for necroptosis-associated events. Importantly, these molecular events in hypoxia-treated human trophoblasts are significantly observed in placental tissue from women with early onset PE. Taken together, we propose that placental pyroptosis is a key event that induces the release of factors into maternal circulation that possibly contribute to severe sterile inflammation and early onset PE pathology.

Endoplasmic reticulum stress disrupts lysosomal homeostasis and induces blockade of autophagic flux in human trophoblasts.

Pregnancy is a stress factor culminating into mild endoplasmic reticulum (ER) stress, which is necessary for placental development. However, excessive or chronic ER stress in pre-eclamptic placentas leads to placental dysfunction. The precise mechanisms through which excessive ER stress impacts trophoblasts are not well understood. Here, we showed that ER stress reduces the number of lysosomes, resulting in inhibition of autophagic flux in trophoblast cells. ER stress also disrupted the translocation of lysosomes to the surface of trophoblast cells, and inhibited lysosomal exocytosis, whereby the secretion of lysosomal-associated membrane protein 1 (LAMP1) into culture media was significantly attenuated. In addition, we found that serum LAMP1 and beta-galactosidase levels were significantly decreased in pre-eclampsia patients compared to normal pregnant women, potentially indicating lysosomal dysfunction through ER stress in pre-eclamptic placentas. Thus, we demonstrated that excessive ER stress essentially disrupts homeostasis in trophoblasts in conjunction with autophagy inhibition by lysosomal impairment.

Current Understanding of Autophagy in Pregnancy.

Autophagy is an evolutionarily conserved process in eukaryotes to maintain cellular homeostasis under environmental stress. Intracellular control is exerted to produce energy or maintain intracellular protein quality controls. Autophagy plays an important role in embryogenesis, implantation, and maintenance of pregnancy. This role includes supporting extravillous trophoblasts (EVTs) that invade the decidua (endometrium) until the first third of uterine myometrium and migrate along the lumina of spiral arterioles under hypoxic and low-nutrient conditions in early pregnancy. In addition, autophagy inhibition has been linked to poor placentation-a feature of preeclamptic placentas-in a placenta-specific autophagy knockout mouse model. Studies of autophagy in human placentas have revealed controversial results, especially with regard to preeclampsia and gestational diabetes mellitus (GDM). Without precise estimation of autophagy flux, wrong interpretation would lead to fixed tissues. This paper presents a review of the role of autophagy in pregnancy and elaborates on the interpretation of autophagy in human placental tissues.