Maternal microvascular dysfunction during preeclamptic pregnancy

Differential Effects of LOX-1 Inhibition on Aortic Structure and Posterior Cerebral Artery Structure and Function in an Experimental Model of Preeclampsia

Preeclampsia is a hypertensive disorder of pregnancy marked by vascular dysfunction, large artery stiffness, and excess oxidized low-density lipoprotein (oxLDL). oxLDL activates oxidative stress pathways which contribute to arterial stiffness through interaction with the lectin-like oxLDL receptor 1 (LOX-1). Increased vascular stiffness is associated with higher pulse wave velocity and downstream microvasculature damage. Here we evaluated the ability of LOX-1 inhibition (LOX-1i) to prevent large artery structural and microvascular structural and functional changes via assessment of the descending thoracic aorta (DTAo) and posterior cerebral arteries (PCA) in a high cholesterol model of preeclampsia. Adult female Sprague Dawley normal late-pregnant (LP) and experimentally preeclamptic (ePE, high cholesterol diet d7-19) animals underwent intraperitoneal (i.p.) implantation of a mini-osmotic pump at d12 containing LOX-1 neutralizing antibodies (ePE + LOX-1i, n = 7) or goat IgG as vehicle control (LP + IgG, n = 8 and ePE + IgG, n = 8). Animals were studied at d19. DTAos and PCAs were removed for histologic assessment and isolated vessel experiments, respectively. Fetuses and placentas were weighed individually. Plasma was analyzed for markers of oxidative stress. ePE + IgG DTAo elastin content (an indirect metric of stiffness) was not significantly different from the LP + IgG group. Nonetheless, trending elastin break and sinuosity data (higher number of breaks and lower sinuosity in the ePE + IgG group compared to LP + IgG) suggested increased stiffness in this high cholesterol PE model. LOX-1i appeared to prevent a decrease in elastin. PCAs showed no structural changes with ePE or LOX-1i. ePE PCAs had increased reactivity to the nitric oxide donor sodium nitroprusside and decreased tone that was unaffected by LOX-1i. ePE animals had increased plasma oxLDL and 3-nitrotyrosine that was unaffected by LOX-1i. Taken together, LOX-1i may improve large artery stiffness without mitigation of the oxidative stress or cerebral microvascular dysfunction seen in ePE. Understanding these mechanisms is important in abating the long-term risks of preeclampsia.

Hepatoprotective effect of prenatal celecoxib in weaning preeclamptic rats: Role of HMGB1/MAPKs signaling

Preeclampsia (PE) is often associated with multiple organ damage that remains noticeable postnatally. Here, we tested the hypotheses that antenatal therapy with nonsteroidal antiinflammatory drugs (NSAIDs) refashions liver damage induced by PE in weaning rats and that the high mobility group box 1 (HMGB1) signaling modulates this interaction. PE was induced by pharmacologic nitric oxide deprivation during the last week of gestation (Nω-nitro-L-arginine methyl ester, L-NAME, 50 mg/kg/day, oral gavage). Compared with control rats, weaning PE rats revealed substantial rises in serum transaminases together with histopathological signs of hepatic cytoplasmic changes, portal inflammation, and central vein dilation. While gestational NSAIDs reversed the elevated transaminases, they had no effects (celecoxib, naproxen) or even worsened (diclofenac) the structural damage. Molecularly, celecoxib was the most effective NSAID in (i) reversing PE-evoked upregulation of hepatic HMGB1 gene expression and concomitant increments and decrements in mitogen-activated protein kinases MAPKERK and MAPKp38 expression, respectively, and (ii) elevating and suppressing serum interleukin-10 and tumor necrosis factor-α, respectively. Alternatively, rises in serum interleukin-1β and shifts in macrophage polarization towards an inflammatory phenotype caused by PE were comparably diminished by all NSAIDs. The data disclose an advantageous therapeutic potential for gestational celecoxib over diclofenac or naproxen in controlling hepatic dysfunction and HMGB1-interrelated inflammatory and oxidative sequels of PE.

High salt intake and HIV infection on endothelial glycocalyx shedding in salt-sensitive hypertension

The endothelial glycocalyx is closely associated with various physiological and pathophysiological events. Significant modification of the endothelial glycocalyx is an early process in the pathogenesis of cardiovascular disease. High dietary salt and HIV infection damages the endothelial glycocalyx causing endothelial dysfunction and increasing the risk for salt-sensitive hypertension and cardiovascular disease. The two factors, HIV infection and dietary salt are critical independent predictors of hypertension and cardiovascular disease and often synergize to exacerbate and accelerate disease pathogenesis. Salt-sensitive hypertension is more common among people living with HIV and is associated with risk for cardiovascular disease, stroke, heart attack and even death. However, the underlying mechanisms linking endothelial glycocalyx damage to dietary salt and HIV infection are lacking. Yet, both HIV infection/treatment and dietary salt are closely linked to endothelial glycocalyx damage and development of salt-sensitive hypertension. Moreover, the majority of individuals globally, consume more salt than is recommended and the burden of HIV especially in sub-Sahara Africa is disproportionately high. In this review, we have discussed the missing link between high salt and endothelial glycocalyx shedding in the pathogenesis of salt-sensitive hypertension. We have further elaborated the role played by HIV infection and treatment in modifying endothelial glycocalyx integrity to contribute to the development of hypertension and cardiovascular disease.

Pregnancy as a susceptible state for thrombotic microangiopathies

Pregnancy and the postpartum period represent phases of heightened vulnerability to thrombotic microangiopathies (TMAs), as evidenced by distinct patterns of pregnancy-specific TMAs (e.g., preeclampsia, HELLP syndrome), as well as a higher incidence of nonspecific TMAs, such as thrombotic thrombocytopenic purpura or hemolytic uremic syndrome, during pregnancy. Significant strides have been taken in understanding the underlying mechanisms of these disorders in the past 40 years. This progress has involved the identification of pivotal factors contributing to TMAs, such as the complement system, ADAMTS13, and the soluble VEGF receptor Flt1. Regardless of the specific causal factor (which is not generally unique in relation to the usual multifactorial origin of TMAs), the endothelial cell stands as a central player in the pathophysiology of TMAs. Pregnancy has a major impact on the physiology of the endothelium. Besides to the development of placenta and its vascular consequences, pregnancy modifies the characteristics of the women's microvascular endothelium and tends to render it more prone to thrombosis. This review aims to delineate the distinct features of pregnancy-related TMAs and explore the contributing mechanisms that lead to this increased susceptibility, particularly influenced by the "gravid endothelium." Furthermore, we will discuss the potential contribution of histopathological studies in facilitating the etiological diagnosis of pregnancy-related TMAs.

Placenta and maternal endothelium during preeclampsia: Disruption of the glycocalyx explains increased inositol phosphoglycans and angiogenic factors in maternal blood

The etiology of the pregnancy syndrome preeclampsia is still unclear, while most hypotheses center on the placenta as the major contributor of the syndrome. Especially changes of the placental metabolism, including the use of glucose to produce energy, are important features. As an example, inositol phosphoglycan P-type molecules, second messengers involved in the glucose metabolism of all cells, can be retrieved from maternal urine of preeclamptic women, even before the onset of clinical symptoms. Alterations in the placental metabolism may subsequently lead to negative effects on the plasma membrane of the placental syncytiotrophoblast. This in turn may have deleterious effects on the glycocalyx of this layer and a disruption of this layer in all types of preeclampsia. The interruption of the glycocalyx in preeclampsia may result in changes of inositol phosphoglycan P-type signaling pathways and the release of these molecules as well as the release of soluble receptors such as sFlt-1 and sEndoglin. The release of placental factors later affects the maternal endothelium and disrupts the endothelial glycocalyx as well. This in turn may pave the way for edema, endothelial dysfunction, coagulation, all typical symptoms of preeclampsia.

Glycocalyx-Sodium Interaction in Vascular Endothelium

The glycocalyx generally covers almost all cellular surfaces, where it participates in mediating cell-surface interactions with the extracellular matrix as well as with intracellular signaling molecules. The endothelial glycocalyx that covers the luminal surface mediates the interactions of endothelial cells with materials flowing in the circulating blood, including blood cells. Cardiovascular diseases (CVD) remain a major cause of morbidity and mortality around the world. The cardiovascular risk factors start by causing endothelial cell dysfunction associated with destruction or irregular maintenance of the glycocalyx, which may culminate into a full-blown cardiovascular disease. The endothelial glycocalyx plays a crucial role in shielding the cell from excessive exposure and absorption of excessive salt, which can potentially cause damage to the endothelial cells and underlying tissues of the blood vessels. So, in this mini review/commentary, we delineate and provide a concise summary of the various components of the glycocalyx, their interaction with salt, and subsequent involvement in the cardiovascular disease process. We also highlight the major components of the glycocalyx that could be used as disease biomarkers or as drug targets in the management of cardiovascular diseases.

Kidney injury molecule-1 and podocalyxin dysregulation in an arginine vasopressin induced rodent model of preeclampsia

OBJECTIVE

To assess renal injury in an arginine vasopressin (AVP) rodent model of preeclampsia.

STUDY DESIGN

Urinary expression of kidney injury molecule-1 (KIM-1), urinary protein and creatinine was determined in rodents (n = 24; pregnant AVP, pregnant saline, non-pregnant AVP and non-pregnant saline), which received a continuous dose of either AVP or saline via subcutaneous mini osmotic pumps for 18 days, using a Multiplex kidney toxicity immunoassay. Renal morphology was assessed using haematoxylin and eosin staining and transmission electron microscopy. The immunolocalization of KIM-1 and podocalyxin was qualitatively evaluated using immunohistochemistry.

RESULTS

Urinary KIM-1 and urinary protein levels were significantly increased in treated vs. untreated rats on gestational days 8 (p < 0.05), 14 (p < 0.001) and 18 (p < 0.001). The pregnant rats displayed a lower trend of creatinine compared to the non-pregnant groups, albeit non-significantly. KIM-1 was immunolocalized in the proximal convoluted tubules in AVP treated vs. untreated groups. In contrast, podocalyxin was weakly immunostained within glomeruli of pregnant AVP treated vs. pregnant untreated rats. Histological evaluation revealed reduced Bowman's space, with some tubular and blood vessel necrosis in the pregnant treated group. Ultrastructural observations included effacement and fusion of podocyte foot processes, glomerular basement membrane abnormalities, podocyte nuclear crenations, mitochondrial oedema and cristae degeneration with cytoplasmic lysis within treated tissue.

CONCLUSION

Our findings demonstrate region-specific kidney injury particularly glomerular impairment and endothelial injury in AVP-treated rats. The findings highlight the utility of this model in studying the mechanisms driving renal damage in a rodent model of preeclampsia.

Clinical value of flow-mediated dilatation of brachial artery in hypertensive disorders complicating pregnancy

Hypertensive disorders complicating pregnancy (HDCP) are common pregnancy-related disorders. In this study, we aimed to study the clinical value of flow-mediated dilation (FMD) in HDCP and its association with endothelial dysfunction and HDCP-related factors. 160 HDCP patients and 120 healthy pregnancies were enrolled in the study. The expressions of endothelial function markers and FMD were determined. In addition, their correlations in HDCP patients were also analyzed using Pearson's correlation analysis. FMD value decreased gradually from normal pregnancy to severe PE. The levels of plasma nitric oxidase (NO) were significantly lower in the HDCP group than those in the control group, while the levels of plasma endothelin-1 (ET-1) were increased dramatically in the HDCP group. Moreover, the levels of placental growth factor (PLGF) in HDCP women were significantly lower, while the soluble FMS-like tyrosine kinase 1 (sFLt-1) levels were markedly higher than those in control. In addition, the FMD value was correlated with the levels of plasma NO, ET-1, PLGF and sFlt1. It was also found that lower levels of FMD correspond to endothelial dysfunction and abnormal concentrations of PLGF and sFlt-1. The FMD value was associated with endothelial function indicators and could be a strong and non-invasive measure to predict HDCP. The association between the FMD values and endothelial function indicators in HDCP could be helpful for the prediction of pregnant hypertension more accurately.

Pathological AT1R-B2R Protein Aggregation and Preeclampsia

Preeclampsia is one of the most frequent and severe complications of pregnancy. Symptoms of preeclampsia usually occur after 20 weeks of pregnancy and include hypertension and kidney dysfunction with proteinuria. Up to now, delivery of the infant has been the most effective and life-saving treatment to alleviate symptoms of preeclampsia because a causative treatment does not exist, which could prolong a pregnancy complicated with preeclampsia. Preeclampsia is a complex medical condition, which is attributed to a variety of different risk factors and causes. Risk factors account for insufficient placentation and impaired vasculogenesis and finally culminate in this life-threatening condition of pregnancy. Despite progress, many pathomechanisms and causes of preeclampsia are still incompletely understood. In recent years, it was found that excessive protein complex formation between G-protein-coupled receptors is a common sign of preeclampsia. Specifically, the aberrant heteromerization of two vasoactive G-protein-coupled receptors (GPCRs), the angiotensin II AT1 receptor and the bradykinin B2 receptor, is a causative factor of preeclampsia symptoms. Based on this knowledge, inhibition of abnormal GPCR protein complex formation is an experimental treatment approach of preeclampsia. This review summarizes the impact of pathological GPCR protein aggregation on symptoms of preeclampsia and delineates potential new therapeutic targets.