Alteration of heat shock protein 70 expression levels in term and preterm delivery

An expert review of environmental heat exposure and stillbirth in the face of climate change: Clinical implications and priority issues

Exposure to extreme heat in pregnancy increases the risk of stillbirth. Progress in reducing stillbirth rates has stalled, and populations are increasingly exposed to high temperatures and climate events that may further undermine health strategies. This narrative review summarises the current clinical and epidemiological evidence of the impact of maternal heat exposure on stillbirth risk. Out of 20 studies, 19 found an association between heat and stillbirth risk. Recent studies based in low- to middle-income countries and tropical settings add to the existing literature to demonstrate that all populations are at risk. Additionally, both short-term heat exposure and whole-pregnancy heat exposure increase the risk of stillbirth. A definitive threshold of effect has not been identified, as most studies define exposure as above the 90th centile of the usual temperature for that population. Therefore, the association between heat and stillbirth has been found with exposures from as low as >12.64°C up to >46.4°C. The pathophysiological pathways by which maternal heat exposure may lead to stillbirth, based on human and animal studies, include both placental and embryonic or fetal impacts. Although evidence gaps remain and further research is needed to characterise these mechanistic pathways in more detail, preliminary evidence suggests epigenetic changes, alteration in imprinted genes, congenital abnormalities, reduction in placental blood flow, size and function all play a part. Finally, we explore this topic from a public health perspective; we discuss and evaluate the current public health guidance on minimising the risk of extreme heat in the community. There is limited pregnancy-specific guidance within heatwave planning, and no evidence-based interventions have been established to prevent poor pregnancy outcomes. We highlight priority research questions to move forward in the field and specifically note the urgent need for evidence-based interventions that are sustainable.

Fetal Lung-Derived Exosomes in Term Labor Amniotic Fluid Induce Amniotic Membrane Senescence

The mechanism of parturition is still unclear. Evidence has shown that delivery is associated with cellular senescence of the amniotic membrane. We isolated fetal lung-associated exosomes from the amniotic fluid from term labor (TL-exos) and verified that the exosomes can cause primary human amniotic epithelial cell (hAEC) senescence and apoptosis and can release higher levels of senescence-associated secretory phenotype (SASP)-related molecules and proinflammatory damage-associated molecular patterns (DAMPs) than exosomes isolated from the amniotic fluid from term not in labor (TNIL-exos). The human lung carcinoma cell lines (A549) can be used as an alternative to alveolar type 2 epithelial cells producing pulmonary surfactant. Therefore, we isolated A549 cell-derived exosomes (A549-exos) and found that they can trigger hAEC to undergo the same aging process. Finally, the animal experiments suggested that A549-exos induced vaginal bleeding and preterm labor in pregnant mice. Therefore, we conclude that exosomes derived from fetal lungs in term labor amniotic fluid induce amniotic membrane senescence, which may provide new insight into the mechanism of delivery.

Integrative genetic, genomic and transcriptomic analysis of heat shock protein and nuclear hormone receptor gene associations with spontaneous preterm birth

Heat shock proteins are involved in the response to stress including activation of the immune response. Elevated circulating heat shock proteins are associated with spontaneous preterm birth (SPTB). Intracellular heat shock proteins act as multifunctional molecular chaperones that regulate activity of nuclear hormone receptors. Since SPTB has a significant genetic predisposition, our objective was to identify genetic and transcriptomic evidence of heat shock proteins and nuclear hormone receptors that may affect risk for SPTB. We investigated all 97 genes encoding members of the heat shock protein families and all 49 genes encoding nuclear hormone receptors for their potential role in SPTB susceptibility. We used multiple genetic and genomic datasets including genome-wide association studies (GWASs), whole-exome sequencing (WES), and placental transcriptomics to identify SPTB predisposing factors from the mother, infant, and placenta. There were multiple associations of heat shock protein and nuclear hormone receptor genes with SPTB. Several orthogonal datasets supported roles for SEC63, HSPA1L, SACS, RORA, and AR in susceptibility to SPTB. We propose that suppression of specific heat shock proteins promotes maintenance of pregnancy, whereas activation of specific heat shock protein mediated signaling may disturb maternal–fetal tolerance and promote labor.

Targeting Toll-like receptor-4 to tackle preterm birth and fetal inflammatory injury

Every year, 15 million pregnancies end prematurely, resulting in more than 1 million infant deaths and long-term health consequences for many children. The physiological processes of labour and birth involve essential roles for immune cells and pro-inflammatory cytokines in gestational tissues. There is compelling evidence that the mechanisms underlying spontaneous preterm birth are initiated when a premature and excessive inflammatory response is triggered by infection or other causes. Exposure to pro-inflammatory mediators is emerging as a major factor in the 'fetal inflammatory response syndrome' that often accompanies preterm birth, where unscheduled effects in fetal tissues interfere with normal development and predispose to neonatal morbidity. Toll-like receptors (TLRs) are critical upstream gatekeepers of inflammatory activation. TLR4 is prominently involved through its ability to sense and integrate signals from a range of microbial and endogenous triggers to provoke and perpetuate inflammation. Preclinical studies have identified TLR4 as an attractive pharmacological target to promote uterine quiescence and protect the fetus from inflammatory injury. Novel small-molecule inhibitors of TLR4 signalling, specifically the non-opioid receptor antagonists (+)-naloxone and (+)-naltrexone, are proving highly effective in animal models for preventing preterm birth induced by bacterial mimetic LPS, heat-killed Escherichia coli, or the TLR4-dependent pro-inflammatory lipid, platelet-activating factor (PAF). Here, we summarise the rationale for targeting TLR4 as a master regulator of inflammation in fetal and gestational tissues, and the potential utility of TLR4 antagonists as candidates for preventative and therapeutic application in preterm delivery and fetal inflammatory injury.

A protocol for an observational cohort study of heat strain and its effect on fetal wellbeing in pregnant farmers in The Gambia

Introduction: Climate change predictions indicate that global temperatures are likely to exceed those seen in the last 200,000 years, rising by around 4°C above pre-industrial levels by 2100 (without effective mitigation of current emission rates). In regions of the world set to experience extreme temperatures, women often work outside in agriculture even during pregnancy. The implications of heat strain in pregnancy on maternal health and pregnancy outcome are not well understood. This protocol describes a study to assess the physiological response of pregnant women to environmental heat stress and the immediate effect this has on fetal wellbeing.

Methods and analysis: The study will be performed in West Kiang district, The Gambia; a semi-arid zone in West Africa with daily maximum temperatures ranging from approximately 32 to 40°C. We will recruit 125 pregnant women of all ages who perform agricultural work during their pregnancy. Participants will be followed every two months until delivery. At each study visit fetal growth will be measured by ultrasound scan. During the course of their working day we will take the following measurements: continuous maternal physiological measurements (heart rate, respiratory rate, chest skin temperature and tri-axis accelerometer data); intermittent maternal tympanic core temperature, four point skin temperature, blood pressure; intermittent fetal heart rate and, if eligible, umbilical artery doppler; intermittent environmental measurements of air temperature, humidity, solar radiation and wind speed. Venous blood and urine will be collected at beginning and end of day for biomarkers of heat strain or fetal distress and hydration status.

A protocol for an observational cohort study of heat strain and its effect on fetal wellbeing in pregnant farmers in The Gambia

Introduction: Climate change predictions indicate that global temperatures are likely to exceed those seen in the last 200,000 years, rising by around 4°C above pre-industrial levels by 2100 (without effective mitigation of current emission rates). In regions of the world set to experience extreme temperatures, women often work outside in agriculture even during pregnancy. The implications of heat strain in pregnancy on maternal health and pregnancy outcome are not well understood. This protocol describes a study to assess the physiological response of pregnant women to environmental heat stress and the immediate effect this has on fetal wellbeing. Methods and analysis: The study will be performed in West Kiang district, The Gambia; a semi-arid zone in West Africa with daily maximum temperatures ranging from approximately 32 to 40°C. We will recruit 125 pregnant women of all ages who perform agricultural work during their pregnancy. Participants will be followed every two months until delivery. At each study visit fetal growth will be measured by ultrasound scan. During the course of their working day we will take the following measurements: continuous maternal physiological measurements (heart rate, respiratory rate, chest skin temperature and tri-axis accelerometer data); intermittent maternal tympanic core temperature, four point skin temperature, blood pressure; intermittent fetal heart rate and, if eligible, umbilical artery doppler; intermittent environmental measurements of air temperature, humidity, solar radiation and wind speed. Venous blood and urine will be collected at beginning and end of day for biomarkers of heat strain or fetal distress and hydration status.

Vaginal Biomarkers That Predict Cervical Length and Dominant Bacteria in the Vaginal Microbiomes of Pregnant Women

In many impoverished regions of the world, it may not be possible to assess two major risk factors for preterm birth: a short cervical length and the depletion of vaginal lactobacilli. We determined whether measuring specific compounds in vaginal fluid might be a simple, noninvasive, and cost-effective way to predict the bacteria that dominate the vaginal microbiome and indicate the presence of a shortened cervix (<25 mm). Vaginal fluid samples were prospectively collected from mid-trimester pregnant women, and the concentrations of d- and l-lactic acid, tissue inhibitor of matrix metalloproteinases TIMP-1 and TIMP-2, matrix metalloproteinases MMP-2 and MMP-8, the 70-kDa heat shock protein, a2 isoform of vacuolar ATPase, and sequestrome-1 were quantified by an enzyme-linked immunosorbent assay (ELISA). The compositions of vaginal microbiomes were assessed by analysis of the V1-V3 regions of 16S rRNA genes, while cervical length was determined by transvaginal ultrasonography. The vaginal microbiomes could be clustered into five community state types (CSTs), four of which were dominated by a single Lactobacillus species. The dominance of Lactobacillus crispatus or Lactobacillus jensenii in the vaginal microbiome predicted the level of d-lactic acid present. Several of the biomarkers, especially TIMP-1, in combination with the subject's age and race, were significantly associated with cervical length. Using piecewise structural equation modeling, we established a causal network that links CST to cervical length via biomarkers. We concluded that measuring levels of TIMP-1 and d-lactic acid in vaginal secretions might be a straightforward way to assess the risk for preterm birth due to a short cervix and microbiome composition.IMPORTANCE Premature birth and its complications are the largest contributors to infant death in the United States and globally. A short cervical length and the depletion of Lactobacillus species are known risk factors for preterm birth. However, in many resource-poor areas of the world, the technology to test for their occurrence is unavailable, and pregnant women with these risk factors are neither identified nor treated. In this study, we used path analysis to gain an unprecedented understanding of interactions between vaginal microbiome composition, the concentrations of various compounds in vaginal secretions, and cervical length. We identified low-cost point-of-care measures that might be used to identify pregnant women at risk for preterm birth. The use of these measures coupled with appropriate preventative or treatment strategies could reduce the incidence of preterm births in poor areas of the world that lack access to more sophisticated diagnostic methods.

Temporal regulation of extracellular signal-regulated kinase 1/2 phosphorylation, heat shock protein 70 and activating transcription factor 3 during prostaglandin F-induced luteal regression in pseudopregnant rats following heat stress

The aim of the present study was to investigate the effects of heat stress on heat shock protein (HSP) 70 expression and mitogen-activated protein kinase (MAPK) and protein kinase (PK) B signalling during prostaglandin F (PGF)-induced luteal regression. During pseudopregnancy, rats were exposed to heat stress (HS, 40°C, 2h) for 7 days and treated with PGF or physiological saline on Day 7; serum and ovaries were collected 0, 1, 2, 8 or 24h after PGF treatment. The early inhibitory effect of PGF on progesterone was reduced in HS rats. HSP70 expression in response to PGF was significantly enhanced in HS rats. PGF-induced phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 was significantly greater in the HS group; however, HS rats exhibited elevated basal levels of phosphorylation of p38 MAPK, but not ERK1/2. PGF treatment increased expression of activating transcription factor (ATF) 3 at 2h, which was inhibited by heat stress. Evaluating PKB signalling revealed that phosphorylation of p-Akt (Thr³⁰⁸ and Ser⁴⁷³) was reduced at 8 and 24h after PGF treatment in both non-heat stress (NHS) and HS groups, but there were no significant differences between the HS and NHS groups at any of the time points. In conclusion, the present study provides further evidence that heat stress may enhance HSP70 and affect ERK1/2 and ATF3 expression, but not Akt activation, during PGF-induced luteal regression in pseudopregnant rats.

Review of the progress toward achieving heat confinement-the holy grail of photothermal therapy

Photothermal therapy (PTT) involves the application of normally benign light wavelengths in combination with efficient photothermal (PT) agents that convert the absorbed light to heat to ablate selected cancers. The major challenge in PTT is the ability to confine heating and thus direct cellular death to precisely where PT agents are located. The dominant strategy in the field has been to create large libraries of PT agents with increased absorption capabilities and to enhance their delivery and accumulation to achieve sufficiently high concentrations in the tissue targets of interest. While the challenge of material confinement is important for achieving “heat and lethality confinement,” this review article suggests another key prospective strategy to make this goal a reality. In this approach, equal emphasis is placed on selecting parameters of light exposure, including wavelength, duration, power density, and total power supplied, based on the intrinsic properties and geometry of tissue targets that influence heat dissipation, to truly achieve heat confinement. This review highlights significant milestones researchers have achieved, as well as examples that suggest future research directions, in this promising technique, as it becomes more relevant in clinical cancer therapy and other noncancer applications.

Treatment with Geranylgeranylacetone Induces Heat Shock Protein 70 and Attenuates Neonatal Hyperoxic Lung Injury in a Model of Bronchopulmonary Dysplasia

Purpose

Bronchopulmonary dysplasia (BPD) is a respiratory complication characterized by abnormal alveolar development in premature infants. Geranylgeranylacetone (GGA) can induce heat shock protein (HSP) 70, which has cytoprotective effects against various stressors. Here, we investigated whether GGA protected neonatal lungs from hyperoxic stress in a murine BPD model, and measured the serum HSP70 levels in preterm humans treated with oxygen.

Methods

Newborn mice were exposed to >90% oxygen and administered GGA or vehicle alone orally on days 1, 2, and 3 of life. At 2 days of age, HSP70 expression in the lung was determined by western blotting. At 8 days of age, the lungs were processed for histological analysis. Radial alveolar count (RAC) and mean linear intercept (MLI) were measured as parameters of alveolarization. Apoptosis was evaluated by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method and cleaved caspase-3 immunohistochemistry. Serum HSP70 levels in preterm humans treated with oxygen were measured by enzyme-linked immunosorbent assay.

Results

GGA administration enhanced the HSP70 expression to two-fold compared with normoxia-exposed and vehicle-treated mice. Hyperoxia reduced HSP70 expression, whereas GGA abrogated the effects. Hyperoxia-exposed mice exhibited more apoptotic cells in lung parenchyma and a more simplified alveolar structure with less RAC and larger MLI than normoxia-exposed mice. GGA suppressed the increase in apoptotic cells and the structural changes of the lungs induced by hyperoxia. Serum HSP70 levels of preterm human infants gradually decreased with age.

Conclusions

GGA may attenuate hyperoxic injury in neonatal lungs and thereby may prevent the development of BPD.

The Role of Hsp70 in the Regulation of Autophagy in Gametogenesis, Pregnancy, and Parturition

Induction of the 70 kDa heat shock protein (hsp70) and autophagy are two major mechanisms that promote cell homeostasis during the rapid cell growth and differentiation characteristic of reproduction. Hsp70 insures proper assembly, conformation, and intracellular transport of nascent proteins. Autophagy removes from the cytoplasm proteins, other macromolecules, and organelles that are no longer functional or needed and recycles their components for synthesis of new products under nutritionally limiting conditions. Hsp70 inhibits autophagy and so a proper balance between these two processes is essential for optimal germ cell production and survival and pregnancy progression. A marked inhibition in autophagy and a concomitant increase in hsp70 at term is a trigger for parturition. Excessive external or endogenous stress that induces a high level of hsp70 production can lead to a non-physiological inhibition of autophagy, resulting in altered spermatogenesis, premature ovarian failure, and complications of pregnancy including preeclampsia, intrauterine growth restriction, and preterm birth.

Gene expression in term placentas is regulated more by spinal or epidural anesthesia than by late-onset preeclampsia or gestational diabetes mellitus

Pre-eclampsia (PE) and gestational diabetes mellitus (GDM) are common complications of pregnancy, but the mechanisms underlying these disorders remain unclear. The aim was to identify the extent of altered gene expression in term placentas from pregnant women with late-onset PE and GDM compared to controls. RNAseq identified few significantly differentially regulated genes in placental biopsies between PE, GDM, or uncomplicated pregnancy (n = 10 each group). Five genes were altered in placentas from PE including 4 non-coding genes and Angiopoietin 2 (ANGPT2). No genes were significantly regulated by GDM. In contrast, many genes were significantly regulated by fetal, maternal and delivery-specific variables, particularly spinal and epidural anesthesia. We selected ANGPT2 and Chemokine (C-X-C motif) ligand 14 (CXCL14) to test with qPCR in a larger set of placentas (n = 475) and found no differences between the groups. However, regression analysis revealed a stronger association between placental ANGPT2 and CXCL14 mRNA expression and fetal, maternal and delivery-specific variables than diagnostic group. To conclude, the gene expression in term placentas are highly affected by fetal, maternal and delivery specific variables. Few regulated genes were found in late-onset PE and GDM placentas, which may suggest that these conditions could be more affected by maternal factors.

Heat-Shock Proteins 70 Induce Pro-Inflammatory Maturation Program in Decidual CD1a(+) Dendritic Cells

PROBLEM

The aim of the study was to assess possible binding of a mixture of constitutive Hsc70 and inducible Hsp70 forms (HSP70) to Toll-like receptor (TLR) 4 and CD91 receptors on decidual CD1a(+) dendritic cells (DCs) and their influence on DCs maturation status.

METHOD OF STUDY

Immunohistology and immunofluorescence of paraffin-embedded first trimetester and term pregnancy decidua were performed together with flow cytometry detection of antigens in DCs after stimulation of decidual mononuclear cells with HSP70.

RESULTS

Hsc70 and Hsp70 labeling revealed intracellular and nuclear staining in trophoblast cells. The numbers of Hsc70(+) and Hsp70(+) cells of decidual tissue were higher in early pregnancy decidua than in decidua at term. HSP70 binds CD91 and TLR4 receptors on CD1a(+) DCs and increased the expression of CD83, HLA-DR, CD80, and CD86, but decreased CC receptor (CCR) 5. HSP70 increased CC ligand (CCL) 3 and CCL22. HSP70 in the concentration of 1 μg/mL increased the percentage of interferon-γ and interleukin (IL)-15-expressing cells over the cells expressing IL-4.

CONCLUSION

HSP70 binds CD91 and TLR4 on decidual CD1a(+) DCs, causes their maturation, and increases IL-15 in the context of Th1 cytokine/chemokine domination, which could support immune response harmful for ongoing pregnancy.

Expression of HSPA12B in acute cardiac allograft rejection in rats

HSP70 may play a more important role in regulating antigen-specific immune response than other HSPs; however, HSPA12B production in transplanted heart remains obscure, which was identified as the newest member of the HSP70 family. In the current study, we performed a heart transplantation model in adult rats and investigated the dynamic changes of HSPA12B expression in the cardiac grafts. The cardiac grafts of allogeneic (Wistar-Lewis rat) and syngeneic (Lewis-Lewis rat) rat models were subjected to histopathological and immunohistochemical analyses for HSPA12B expression on days 0-7 after operation. We also examined the expression profiles of active caspase-3, whose changes were correlated with the expression profiles of HSPA12B. Our results demonstrated that HSPA12B protein exhibited biphasic patterns in transplanted heart. The first expression phase correlated with ischemical reperfusion injury over 2 days post-transplant. The second peak of HSPA12B expression was found only in allografts on day 5, concurrent with the expression of caspase-3. Immunohistochemical assay showed that compared with rare expression in isografts, there were significant protein expressions of HSPA12B and caspase-3 in heart allografts from day 5 to 7 post-transplant. Furthermore, double immunofluorescence staining for active caspase-3 and HSPA12B in isografts and allografts at day 5 post-transplant were analyzed and colocalization of HSPA12B/active caspase-3 was detected in allografts. In conclusion, this is the first description of HSPA12B expression in acute cardiac allograft rejection. Our results suggested that HSPA12B might play crucial roles in heart pathophysiology after transplantation.