Pregnancy differentially regulates the collagens types I and III in left ventricle from rat heart

Mechanisms of myocardial reverse remodelling and its clinical significance: A scientific statement of the ESC Working Group on Myocardial Function

Cardiovascular disease (CVD) is the leading cause of morbimortality in Europe and worldwide. CVD imposes a heterogeneous spectrum of cardiac remodelling, depending on the insult nature, that is, pressure or volume overload, ischaemia, arrhythmias, infection, pathogenic gene variant, or cardiotoxicity. Moreover, the progression of CVD-induced remodelling is influenced by sex, age, genetic background and comorbidities, impacting patients' outcomes and prognosis. Cardiac reverse remodelling (RR) is defined as any normative improvement in cardiac geometry and function, driven by therapeutic interventions and rarely occurring spontaneously. While RR is the outcome desired for most CVD treatments, they often only slow/halt its progression or modify risk factors, calling for novel and more timely RR approaches. Interventions triggering RR depend on the myocardial insult and include drugs (renin-angiotensin-aldosterone system inhibitors, beta-blockers, diuretics and sodium-glucose cotransporter 2 inhibitors), devices (cardiac resynchronization therapy, ventricular assist devices), surgeries (valve replacement, coronary artery bypass graft), or physiological responses (deconditioning, postpartum). Subsequently, cardiac RR is inferred from the degree of normalization of left ventricular mass, ejection fraction and end-diastolic/end-systolic volumes, whose extent often correlates with patients' prognosis. However, strategies aimed at achieving sustained cardiac improvement, predictive models assessing the extent of RR, or even clinical endpoints that allow for distinguishing complete from incomplete RR or adverse remodelling objectively, remain limited and controversial. This scientific statement aims to define RR, clarify its underlying (patho)physiologic mechanisms and address (non)pharmacological options and promising strategies to promote RR, focusing on the left heart. We highlight the predictors of the extent of RR and review the prognostic significance/impact of incomplete RR/adverse remodelling. Lastly, we present an overview of RR animal models and potential future strategies under pre-clinical evaluation.

Stretch-induced compliance mechanism in pregnancy-induced cardiac hypertrophy and the impact of cardiovascular risk factors

Pressure overload-induced hypertrophy compromises cardiac stretch-induced compliance (SIC) after acute volume overload (AVO). We hypothesized that SIC could be enhanced by physiological hypertrophy induced by pregnancy's chronic volume overload. This study evaluated SIC-cardiac adaptation in pregnant women with or without cardiovascular risk (CVR) factors. Thirty-seven women (1st trimester, 1stT) and a separate group of 31 (3rd trimester, 3rdT) women [healthy or with CVR factors (obesity and/or hypertension and/or with gestational diabetes)] underwent echocardiography determination of left ventricular end-diastolic volume (LVEDV) and E/e' before (T0), immediately after (T1), and 15 min after (T2; SIC) AVO induced by passive leg elevation. Blood samples for NT-proBNP quantification were collected before and after the AVO. Acute leg elevation significantly increased inferior vena cava diameter and stroke volume from T0 to T1 in both 1stT and 3rdT, confirming AVO. LVEDV and E/e' also increased immediately after AVO (T1) in both 1stT and 3rdT. SIC adaptation (T2, 15 min after AVO) significantly decreased E/e' in both trimesters, with additional expansion of LVEDV only in the 1stT. NT-pro-BNP increased slightly after AVO but only in the 1stT. CVR factors, but not parity or age, significantly impacted SIC cardiac adaptation. A distinct functional response to SIC was observed between 1stT and 3rdT, which was influenced by CVR factors. The LV of 3rdT pregnant women was hypertrophied, showing a structural limitation to dilate with AVO, whereas the lower LV filling pressure values suggest increased diastolic compliance.NEW & NOTEWORTHY The sudden increase of volume overload triggers an acute myocardial stretch characterized by an immediate rise in contractility by the Frank-Starling mechanism, followed by a progressive increase known as the slow force response. The present study is the first to characterize echocardiographically the stretch-induced compliance (SIC) mechanism in the context of physiological hypertrophy induced by pregnancy. A distinct functional adaptation to SIC was observed between first and third trimesters, which was influenced by cardiovascular risk factors.

Are fetal microchimerism and circulating fetal extracellular vesicles important links between spontaneous preterm delivery and maternal cardiovascular disease risk?

Trafficking and persistence of fetal microchimeric cells (fMCs) and circulating extracellular vesicles (EVs) have been observed in animals and humans, but their consequences in the maternal body and their mechanistic contributions to maternal physiology and pathophysiology are not yet fully defined. Fetal cells and EVs may help remodel maternal organs after pregnancy-associated changes, but the cell types and EV cargos reaching the mother in preterm pregnancies after exposure to various risk factors can be distinct from term pregnancies. As preterm delivery-associated maternal complications are rising, revisiting this topic and formulating scientific questions for future research to reduce the risk of maternal morbidities are timely. Epidemiological studies report maternal cardiovascular risk as one of the major complications after preterm delivery. This paper suggests a potential link between fMCs and circulating EVs and adverse maternal cardiovascular outcomes post-pregnancies, the underlying mechanisms, consequences, and methods for and how this link might be assessed.

Cardiovascular risk factors during pregnancy impact the postpartum cardiac and vascular reverse remodeling

Pregnant women with cardiovascular risk (CVR) factors are highly prone to develop cardiovascular disease later in life. Thus, recent guidelines suggest extending the follow-up period to 1 yr after delivery. We aimed to evaluate cardiovascular remodeling during pregnancy and determine which CVR factors and potential biomarkers predict postpartum cardiac and vascular reverse remodeling (RR). Our study included a prospective cohort of 76 healthy and 54 obese and/or hypertensive and/or with gestational diabetes pregnant women who underwent transthoracic echocardiography, pulse-wave velocity (PWV), and blood collection at the 1st trimester (1T) and 3rd trimester (3T) of pregnancy as well as at the 1st/6th/12th mo after delivery. Generalized linear mixed-effects models was used to evaluate the extent of RR and its potential predictors. Pregnant women develop cardiac hypertrophy, as confirmed by a significant increase in left ventricular mass (LVM). Moreover, ventricular filling pressure (E/e') and atrial volume increased significantly during gestation. Significant regression of left ventricular (LV) volume, LVM, and filling pressures was observed as soon as 1 mo postpartum. The LV global longitudinal strain worsened slightly and recovered at 6 mo postpartum. PWV decreased significantly from 1T to 3T and normalized at 1 mo postpartum. We found that arterial hypertension, smoking habits, and obesity were independent predictors of increased LVM during pregnancy and postpartum. High C-reactive protein (CRP) and low ST2/IL33-receptor levels are potential circulatory biomarkers of worse LVM regression. Arterial hypertension, age, and gestational diabetes positively correlated with PWV. Altogether, our findings pinpoint arterial hypertension as a critical risk factor for worse RR and CRP, and ST2/IL33 receptors as potential biomarkers of postpartum hypertrophy reversal.NEW & NOTEWORTHY This study describes the impact of cardiovascular risk factors (CVR) in pregnancy-induced remodeling and postpartum reverse remodeling (up to 1 yr) by applying advanced statistic methods (multivariate generalized linear mixed-effects models) to a prospective cohort of pregnant women. Aiming to extrapolate to pathological conditions, this invaluable "human model" allowed us to demonstrate that arterial hypertension is a critical CVR for worse RR and that ST2/IL33-receptors and CRP are potential biomarkers of postpartum hypertrophy reversal.

Regression of cardiac hypertrophy in health and disease: mechanisms and therapeutic potential

Left ventricular hypertrophy is a leading risk factor for cardiovascular morbidity and mortality. Although reverse ventricular remodelling was long thought to be irreversible, evidence from the past three decades indicates that this process is possible with many existing heart disease therapies. The regression of pathological hypertrophy is associated with improved cardiac function, quality of life and long-term health outcomes. However, less than 50% of patients respond favourably to most therapies, and the reversibility of remodelling is influenced by many factors, including age, sex, BMI and disease aetiology. Cardiac hypertrophy also occurs in physiological settings, including pregnancy and exercise, although in these cases, hypertrophy is associated with normal or improved ventricular function and is completely reversible postpartum or with cessation of training. Studies over the past decade have identified the molecular features of hypertrophy regression in health and disease settings, which include modulation of protein synthesis, microRNAs, metabolism and protein degradation pathways. In this Review, we summarize the evidence for hypertrophy regression in patients with current first-line pharmacological and surgical interventions. We further discuss the molecular features of reverse remodelling identified in cell and animal models, highlighting remaining knowledge gaps and the essential questions for future investigation towards the goal of designing specific therapies to promote regression of pathological hypertrophy.

Tissue inhibitor of metalloproteinase-4 deletion in mice impacts maternal cardiac function during pregnancy and postpartum

Reversible physiological cardiac hypertrophy of the maternal heart occurs during pregnancy and involves extracellular matrix (ECM) remodeling. Previous mouse studies revealed that changes in ECM molecules accompany functional changes in the left ventricle (LV) during late pregnancy and postpartum. We evaluated the effect of global Timp4 deletion in female mice on LV functional parameters and ECM molecules during pregnancy and the postpartum period. Heart weights normalized to tibia lengths were increased in Timp4 knockout (Timp4 KO) virgin, pregnant, and postpartum day 2 mice compared with wild types. Serial echocardiography performed on pregnancy days 10, 12, and 18 and postpartum days (ppds) 2, 7, 14, 21, and 28 revealed that both wild-type and Timp4 KO mice increased end systolic and end diastolic volumes (ESV, EDV) by mid to late pregnancy compared with virgins, with EDV changes persisting through the postpartum period. When compared with wild types, Timp4 KO mice exhibited higher ejection fractions in virgins, at pregnancy days 10 and 18 and ppd2 and ppd14. High-molecular weight forms of COL1A1 and COL3A1 proteins in LV were greater in Timp4 KO virgins, and COL1A1 was higher in late pregnancy and on ppd2 compared with wild types. With exceptions, Timp4 KO mice during late pregnancy and the early postpartum period were able to maintain stroke volume similar to wild-type mice through increased ejection fraction. Although TIMP4 deletion in females exhibited altered ECM molecules, it did not adversely affect cardiac function during first pregnancies and lactation.NEW & NOTEWORTHY Pregnancy and lactation increase volume load on the heart. Defects in cardiac remodeling during pregnancy and postpartum can result in peripartum cardiomyopathy. TIMPs participate in cardiac remodeling. The present study reports the cardiac function in Timp4 knockout adult female mice during pregnancy and lactation. Timp4 knockout females at many time points have higher ejection fraction to maintain stroke volume. Global deletion of Timp4 was not detrimental to maternal heart function during first pregnancies and lactation.

A case report of pregnancy in untreated alkaptonuria - Focus on urinary tissue remodelling markers

A 34-year old woman with alkaptonuria had an elective pregnancy, during which she collected urine samples over the duration of her pregnancy until parturition. She had been attending the National Alkaptonuria Centre from the age of 31 years and continued to attend after delivery for a further three annual visits. Data from her NAC visits as well as urine samples collected during pregnancy were analysed. Urine CTX-1/urine creatinine, urine αCTX-I/ urine creatinine, urine CTX-II/ urine creatinine, and urine C3M/urine creatinine all showed a rapid increase early in pregnancy, returning to baseline before increasing in late pregnancy, indicating significant remodelling of bone, subchondral bone, cartilage and other organs and connective tissue rich in collagens I, II and III. The pattern of tissue remodelling in AKU pregnancy has been described for the very first time. Further research is needed to understand pregnancy in AKU.

Cardiac hypertrophy with obesity is augmented after pregnancy in C57BL/6 mice

BACKGROUND

Over a third of reproductive-age women in the USA are obese, and the prevalence of cardiovascular disease (CVD) is rising in premenopausal women. Cardiac hypertrophy is an independent predictor of CVD. In contrast to pregnancy, where transiently increased left ventricular (LV) mass is not associated with cardiac damage, obesity-mediated cardiac hypertrophy is pathological. There is a paucity of data describing the effect of obesity during pregnancy on maternal cardiovascular health. The purpose of this study was to determine the long-term effect of obesity during pregnancy on cardiac function and structure in mice.

METHODS

Female C57BL/6 J mice were fed a high-fat (HF) or a low-fat (LF) diet for 20 weeks. After 4 weeks, LF- and HF-fed female mice were either crossed with males to become pregnant or remained non-pregnant controls. Following delivery, pups were euthanized, and females maintained on respective diets. After 20 weeks of diet feeding, cardiac function was quantified by echocardiography, and plasma leptin and adiponectin concentrations quantified in LF- and HF-fed postpartum and nulliparous females. mRNA abundance of genes regulating cardiac hypertrophy and remodeling was quantified from left ventricles using the NanoString nCounter Analysis System. Cardiac fibrosis was assessed from picrosirius red staining of left ventricles.

RESULTS

HF-fed postpartum mice had markedly greater weight gain and fat mass expansion with obesity, associated with significantly increased LV mass, cardiac output, and stroke volume compared with HF-fed nulliparous mice. Plasma leptin, but not adiponectin, concentrations were correlated with LV mass in HF-fed females. HF feeding increased LV posterior wall thickness; however, LV chamber diameter was only increased in HF-fed postpartum females. Despite the marked increase in LV mass in HF-fed postpartum mice, mRNA abundance of genes regulating fibrosis and interstitial collagen content was similar between HF-fed nulliparous and postpartum mice. In contrast, only HF-fed postpartum mice exhibited altered expression of genes regulating the extracellular matrix.

CONCLUSIONS

These results suggest that the combined effects of pregnancy and obesity augment cardiac hypertrophy and promote remodeling. The rising prevalence of CVD in premenopausal women may be attributed to an increased prevalence of women entering pregnancy with an overweight or obese BMI.

Matrix Metalloproteinases System and Types of Fibrosis in Rat Heart during Late Pregnancy and Postpartum

Background and objectives: Cardiac remodeling in pregnancy and postpartum is poorly understood. The aim of this study was to evaluate changes in cardiac fibrosis (pericardial, perivascular, and interstitial), as well as the expression of matrix metalloproteinases (MMP-1, MMP-2, and MMP-9) and their inhibitors (Tissue inhibitors of metalloproteinases, TIMP-1 and TIMP-4) during late pregnancy and postpartum in rat left ventricle. Materials and Methods: Female Sprague–Dawley rats were used for this study. Rats were divided three groups: non-pregnant, late pregnancy, and postpartum. The heart was weighed and cardiac fibrosis was studied by conventional histological procedures. The expression and transcript level of target proteins were evaluated using immunoblot techniques and quantitative PCR. Results: The experiments showed an increase of perivascular, pericardial, and interstitial fibrosis in heart during pregnancy and its reversion in postpartum. Moreover, in late pregnancy, MMP-1, MMP-2, and MMP-9 metalloproteinases were downregulated and TIMP-1 and TIMP-4 were upregulated in left ventricle. Conclusions: Our data suggest that the metalloproteinases system is involved in the cardiac extracellular matrix remodeling during pregnancy and its reversion in postpartum, this improves the knowledge of the adaptive cardiac remodeling in response to a blood volume overload present during pregnancy.

Cardioprotection of salvianolic acid B and ginsenoside Rg1 combination on subacute myocardial infarction and the underlying mechanism

BACKGROUND

Following myocardial infarction (MI), a series of structural and functional changes evolves in the myocardium, collectively defined as cardiac remodeling.

PURPOSE

The aim of present study was to investigate the cardioprotection of salvianolicacid B (SalB) and ginsenoside Rg1 (Rg1) combination against cardiac remodeling in a rat model at the subacute phase of MI and further elucidate the underlying mechanism.

METHODS

Rat heart was exposed via a left thoracotomy at the fourth intercostal space and MI was induced by a ligature below the left descending coronary artery. Hemodynamic assay was conducted using a Mikro-tipped SPR-320 catheter which was inserted through the right carotid artery into left ventricle.Myocardial infarct size was detected using 3,5-triphenyltetrazolium chloride (TTC) staining. Haematoxylin and eosin (HE) stain and picric sirius red stain were conducted for histopathological detection. Immunohistochemistry was used to detect the expression of α-smooth muscle actin (α-SMA) and gelatin zymography was used to evaluate the activities of matrix metalloproteinase-9 (MMP-9).

RESULTS

Comparing with MI rats, 30 mg/kg SalB-Rg1 improved cardiac function verified by maximum rate of pressure development for contraction (+dp/dt_max, p < 0.01) and maximum rate of pressure development for relaxation (-dp/dt_max, p < 0.05); reduced myocardial infarct size (p < 0.05) verified by TTC staining, improved cardiac structure based on HE stain; decreased collagen volume fraction (p < 0.05) and collagen I/III ratio (p < 0.05) according picrosirius red staining. The underlying mechanism of SalB-Rg1 against cardiac remodeling was associated with its down-regulation on α-SMA expression according immunohistochemistry (p < 0.01) and inhibition on MMP-9 activity based on in-gel zymography (p < 0.05).

CONCLUSION

All above study indicated the potential therapeutic effects of SalB-Rg1 on heart.

Cardiac Extracellular Matrix Modification as a Therapeutic Approach

The cardiac extracellular matrix (cECM) is comprised of proteins and polysaccharides secreted by cardiac cell types, which provide structural and biochemical support to cardiovascular tissue. The roles of cECM proteins and the associated family of cell surface receptor, integrins, have been explored in vivo via the generation of knockout experimental animal models. However, the complexity of tissues makes it difficult to isolate the effects of individual cECM proteins on a particular cell process or disease state. The desire to further dissect the role of cECM has led to the development of a variety of in vitro model systems, which are now being used not only for basic studies but also for testing drug efficacy and toxicity and for generating therapeutic scaffolds. These systems began with 2D coatings of cECM derived from tissue and have developed to include recombinant ECM proteins, ECM fragments, and ECM mimics. Most recently 3D model systems have emerged, made possible by several developing technologies including, and most notably, 3D bioprinting. This chapter will attempt to track the evolution of our understanding of the relationship between cECM and cell behavior from in vivo model to in vitro control systems. We end the chapter with a summary of how basic studies such as these have informed the use of cECM as a direct therapy.

Inhibition of microRNA-132 attenuates inflammatory response and detrusor fibrosis in rats with interstitial cystitis via the JAK-STAT signaling pathway

Interstitial cystitis (IC) is a heterogeneous syndrome with unknown etiology, and microRNAs (miRs) were found to be involved in IC. In our study, we aim to explore the role of miR-132 in the inflammatory response and detrusor fibrosis in IC through the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway in rat models. A rat model of IC was established and treated with the miR-132 mimic, miR-132 inhibitor, and/or JAK-STAT signaling pathway inhibitor AG490. Enzyme-linked immunosorbent assay was applied to measure the expression of interleukin (IL)-6, IL-10, interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α), and intercellular adhesion molecule-1 (ICAM-1). The urodynamic test was performed to assess urodynamic parameters, and reverse transcription quantitative polymerase chain reaction and Western blot analysis for the expression of miR-132, STAT4, suppressors of cytokine signaling 3 (SOCS3), JAK2, vascular endothelial growth factor (VEGF), IFN-γ, and TNF-α. IC rats treated with miR-132 inhibitor and AG490 had decreased collagen fiber, inflammatory cell infiltration, and mast cells, lower expression of IL-6, IL-10, IFN-γ, TNF-α, ICAM-1, collagens I and III, and alleviated urodynamic parameters and decreased expression of STAT4, VEGF, JAK2, IFN-γ, TNF-α, and increased expression of SOCS3. Taken together, our data indicate that downregulation of miR-132 alleviates inflammatory response and detrusor fibrosis in IC via the inhibition of the JAK-STAT signaling pathway.

Maternal cardiac messenger RNA expression of extracellular matrix proteins in mice during pregnancy and the postpartum period

IMPACT STATEMENT

This study provides the first comprehensive analysis of extracellular matrix protein (ECM) gene expression combined with echocardiographic analyses of heart functional parameters in the murine heart during pregnancy and the early postpartum period. Our findings show regulation of all Timp, selected Mmps, and Col1a1, Col3a1, and Col8a1 mRNA levels with reproductive status, with the greatest number of significant changes occurring in the early postpartum period. Left ventricle cardiac diastolic parameters were the first to change during pregnancy and remained elevated postpartum, whereas systolic parameters were increased in late pregnancy and began to recover during the first week postpartum. These novel findings indicate that although some ECM genes are elevated during late pregnancy, that the postpartum period is a time of robust altered ECM gene expression. These studies provide a basis for examining ECM proteins and their activities in the normal pregnant and postpartum heart and in models of postpartum cardiomyopathy.

Impact of Immune Deficiency on Remodeling of Maternal Resistance Vasculature 4 Weeks Postpartum in Mice

Pregnancy manifests changes in the vascular and immune systems that persist postpartum (PP), have important implications for future pregnancies, and may modify responses to cardiovascular stress in late life. The association between immune and vascular function and the generation or progression of cardiovascular disease beg the question of whether altered immunity modifies pregnancy-induced changes in the vasculature. Our objective was to compare changes in the function and remodeling of systemic resistance vessels 4 weeks PP in normal C57BL/6 (B6), and immunodeficient mice recombinase 1-deficient/B6 ( Rag1^-/-). Immune deficiency did not change the responsiveness to acetylcholine (ACh) and phenylephrine at baseline but decreased arterial distensibility and increased stiffness PP. Adoptive transfer of CD8 T cells into Rag1^-/- mice decreased the response to ACh while increasing distensibility and wall thickness. When compared to PP Rag1^-/-, vessels from PP CD4-deficient mice, which have B cells and CD8 T cells, but no CD4 cells, show increased distensibility and decreased responsiveness to ACh in a pattern similar to that seen in Rag1^-/- given CD8 T cells prior to mating. These studies suggest a key role for T cell, particularly CD8 T cell, associated factors in the PP remodeling of maternal resistance vessels.

Effect of vitamin C on collagen structure of cardinal and uterosacral ligaments during pregnancy

OBJECTIVE

This study aimed to investigate changes in collagen structure in the cardinal and uterosacral ligaments of rats that were administered vitamin C during pregnancy.

STUDY DESIGN

Eighteen female rats were divided into three groups: six pregnant rats administered 1.25mg/ml/day of vitamin C during pregnancy (Group A); six non-pregnant rats that were not administered vitamin C (Group B); and six pregnant rats that were not administered vitamin C during pregnancy (Group C). Fifteen days after delivery, the uteruses of all rats were removed. The intensity of staining (mild, moderate or severe) and the extent of positive staining areas (%) of type I and type III collagen H scores for types I and III collagen, and intensity of elastin fibres in the cardinal and uterosacral ligaments were investigated immunohistochemically. Differences between groups were analysed using Kruskal-Wallis and independent samples tests.

RESULTS

The intensity and extent of type I and type III collagen, the H scores for type I and type III collagen, and the ratio of type III collagen H score: type I collagen H score differed significantly between groups. Pregnant rats administered vitamin C (Group A) had significantly higher values compared with non-pregnant rats (Group B): intensity of type I collagen (p=0.001), extent of type I collagen (p≤0.001), H score for type I collagen (p≤0.001), intensity for type III collagen (p=0.002), extent of type IV collagen (p=0.007), H score for type III collagen (p=0.017), type III collagen H score: type I collagen H score (p=0.039) and intensity of elastin fibres (p=0.097). A significant difference in the ratio of type III collagen H score: type I collagen H score was found between pregnant rats administered vitamin C (Group A) and pregnant rats not administered vitamin C (Group C) (p=0.002).

CONCLUSIONS

The administration of vitamin C to rats during pregnancy had a favourable impact on collagen structure in the cardinal and uterosacral ligaments, suggesting that vitamin C supplementation during pregnancy may help to prevent pelvic organ prolapse and stress urinary incontinence.