Animal Models Of Hypertension Research Articles

The FSGS protein actinin-4 (ACTN4) interacts with NKCC2 to regulate Thick Ascending Limb (TAL) NaCl reabsorption.

In the kidney, the thick Ascending Limb (TAL) of the loop of Henle is crucial for NaCl homeostasis and blood pressure regulation. In animal models of salt-sensitive hypertension, NaCl reabsorption via the apical Na+/K+/2Cl cotransporter (NKCC2) is abnormally increased in the TAL. We showed that NaCl reabsorption is controlled by the presence of NKCC2 at the apical surface of TALs. However, the molecular mechanisms that maintain the steady-state levels of NKCC2 at the apical surface are not clearly understood. Here, we report that NKCC2 interacts with the F-actin cross-linking protein actinin-4 (ACTN4). We find that ACTN4 is expressed in TALs by Western blot and immunofluorescence microscopy. ACTN4 immunoprecipitated with NKCC2 and recombinant GST-ACTN4 pulled down NKCC2 from TAL lysates. ACTN4 is involved in endocytosis in other cells. Therefore, we hypothesized that ACTN4 binds apical NKCC2 and regulates its trafficking. To study this, we silenced ACTN4 in vivo via shRNA or CRISPR/Cas9 system to decrease ACTN4 expression in TALs. We observed that silencing ACTN4 in vivo via shRNA or CRISPR/Cas9 system increased the amount NKCC2 at the apical surface of TALs. Bumetanide-induced diuresis and natriuresis were enhanced by 35% after silencing of ACTN4 in vivo (AV-NKCC2-Cas9: 3841±709 vs AAV-gRNA-ACTN4: 5546±622 µmols Na/8h, n=5, p<0.05). We conclude that ACTN4, binds NKCC2 to regulate its surface expression. Selective depletion of ACTN4 in TALs using shRNA or CRISPR/Cas9 enhances surface NKCC2 and TAL NaCl reabsorption, indicating that regulation of the ACTN4-NKCC2 interaction is important for renal NaCl reabsorption and could be related to hypertension.

The association of leptin and incident hypertension in the reasons for geographic and racial differences in stroke (REGARDS) cohort.

Leptin is an adipokine associated with obesity and with hypertension in animal models. Whether leptin is associated with hypertension independent of obesity is unclear. Relative to White adults, Black adults have higher circulating leptin concentration. As such, leptin may mediate some of the excess burden of incident hypertension among Black adults. REGARDS enrolled 30,239 adults aged ≥45 years from 48 US states in 2003-07. Baseline leptin was measured in a sex- and race-stratified sample of 4400 participants. Modified Poisson regression estimated relative risk (RR) of incident hypertension (new ≥140/≥90 mmHg threshold or use of antihypertensives) per SD of log-transformed leptin, stratified by obesity (BMI of 30 kg/m2). Inverse odds ratio weighting estimated the % mediation by leptin of the excess hypertension RR among Black relative to White participants. Among the 1821 participants without prevalent hypertension, 35% developed incident hypertension. Obesity modified the relationship between leptin and incident hypertension (P-interaction 0.006) such that higher leptin was associated with greater hypertension risk in the crude model among those with BMI < 30 kg/m2, but not those with BMI ≥ 30 kg/m2. This was fully attenuated when adjusting for anthropometric measures. In the crude model, Black adults had a 52% greater risk of incident hypertension. Leptin did not significantly mediate this disparity. In this national U.S. sample, leptin was associated with incident hypertension among non-obese but not obese adults. Future investigations should focus on the effect of weight modification on incident hypertension among non-obese adults with elevated leptin.

Characterization of long-term interleukin-33 administration as an animal model of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by the severe obstruction of the small pulmonary arteries and concomitant high pulmonary arterial pressure, resulting in progressive right ventricular failure. Previously, we demonstrated that long-term interleukin (IL)-33 administration in mice induces severe occlusive medial hypertrophy of pulmonary arteries (PA) in the lungs, which is mediated by group 2 innate lymphoid cells (ILC2s). In response to IL-33, ILC2s accumulate around the blood vessels and produce IL-5, leading to perivascular eosinophil recruitment. In this study, we characterized IL-33-induced medial hypertrophy of PA. We demonstrated that long-term IL-33 administration causes an increase in right ventricular pressure. In IL-33-deficient mice, medial hypertrophy of PA mediated by eggs of Schistosoma mansoni was attenuated, accompanied by a partial reduction in ILC2s, eosinophils, and CD4+ T cells. In addition, proteomic analysis revealed dramatic changes in the urine samples from mice treated with IL-33 or S. mansoni eggs. Resistin-like alpha (RELMα), a pulmonary hypertension-related molecule, was commonly detected in the urine in both treatments. Large amounts of RELMα were observed in the lungs of the IL-33-treated mice. These observations suggest that IL-33-induced medial hypertrophy of PA is a useful model for studying the mechanism underlying the development of PAH and finding biomarkers to indicate the onset of PAH.

In Vivo Models of Steroid-Induced Intraocular Hypertension

Corticosteroids are widely utilized for their anti-inflammatory and immunosuppressive properties but often lead to ocular complications, including ocular hypertension. If untreated, ocular hypertension can progress to optic nerve atrophy and eventually result in steroid-induced glaucoma, which poses a risk of irreversible visual damage. Approximately 40% of individuals experience increased intraocular pressure after steroid use, and around 6% develop glaucoma. Although steroid-induced glaucoma is usually temporary and reversible if the treatment duration is under a year, prolonged exposure can cause permanent vision impairment. The pathogenesis of steroid-induced glaucoma is suggested to arise from increased outflow resistance of aqueous humor, primarily due to decreased expression of matrix metalloproteinases. This deficiency promotes the deposition of extracellular matrix and the dysfunction of trabecular meshwork cells. Additionally, modifications in the actin cytoskeleton increase the stiffness and alter the morphology of trabecular meshwork, further impeding aqueous humor outflow. Molecular changes, such as elevated expression of the MYOC gene, have also been implicated in restricting aqueous outflow. Various animal models, including rats, mice, primates, rabbits, cattle, sheep, cats, and dogs, have been developed to study steroid-induced glaucoma. These models exhibit pathological, pathophysiological, and molecular similarities to human disease, making them valuable for research. This review aims to summarize common animal models of steroid-induced ocular hypertension, discussing their advantages and limitations. The goal is to help researchers select appropriate models for future studies, thereby advancing the understanding of disease mechanisms and developing preventive strategies.

Effect of Dietary Enrichment with Hempseed (Cannabis sativa L.) on Blood Pressure Changes in Growing Mice between Ages of 5 and 30 Weeks

Dietary hempseed (Cannabis sativa L.) reduces blood pressure in adults and animal models of hypertension; however, whether hempseed consumption throughout early life reduces adult blood pressure is not known. This study tested the hypothesis that hempseed enrichment versus a control diet modifies the age-dependent pattern of blood pressure changes in growing female C57BL/6 mice and results in lower adult blood pressure. From ages 5 to 30 weeks, early post-weaning to mid-adulthood, mice were fed either a control AIN-93G (0%), 50 g/kg (5%), or 150 g/kg (15%) hempseed-supplemented diet (n = 8 per group). Biweekly measurements of systolic, diastolic, and mean arterial pressure were collected using the tail-cuff method. Mice fed 5% or 15% hempseed versus the control diet exhibited no significant differences in systolic, diastolic, or mean arterial blood pressure (repeated measures ANOVA main effect of diet, p &gt; 0.05). Blood pressure did not differ significantly between diet groups in adulthood (p &gt; 0.05). However, mice fed a control or 5% hempseed, but not 15% hempseed, diet exhibited blood pressure changes across age marked by significant increases during early adulthood (weeks 11–17) versus early post-weaning (week 5) (p &lt; 0.05). In conclusion, long-term dietary hempseed enrichment at 5% and 15% concentrations during development does not reduce adult blood pressure, but a 15% dose blunts the temporary increase in blood pressure during early adulthood seen in mice fed a control diet.

Abstract P395: Activated T cells from Bph/2 Mice Have an Attenuated Cytokine Response to a Polyclonal T Cell Activator Compared to T cells from Bpn/3 Mice

Numerous studies point to a role for the immune system in various animal models of hypertension. However, there is little known about the immune system of Bph/2 mice, a spontaneously hypertensive mouse model. To address this, the purpose of the current study was a comprehensive comparison of the cytokine response of activated T cells from Bph/2 mice and Bpn/3 normotensive controls. To implement this, we quantified cytokine secretion from cell supernatants from anti-CD3/anti-CD28-activated splenocytes derived from either Bph/2 mice or the normotensive Bpn/3 control mice. In comparison to Bph/2 mice, activated T cells from Bpn/3 mice secreted greater levels of cytokines including, IL-2, IL-3, IL-4, IL-5, IFNγ, GM-CSF, TNFβ and TNFα. We noticed a particularly marked discrepancy in Th17 cytokines where T cells from Bph/2 mice had little to no induction of IL-17F (0 ± 0 pg/ml), IL-21 (1.388 ± 1.388 pg/ml) and IL-22 (1.922 ± 0.633 pg/ml ) in comparison to T cells from Bpn/3 mice (IL-17F: 2.972 ± 1.525 pg/ml; IL-21: 16.48 ± 8.368 pg/ml; IL-22: 62.84 ± 15.94 pg/ml) which showed a measurable induction of these cytokines. Likewise, the IL-17A response was lower in T cells from Bph/2 mice (19.23 ± 5.576 pg/ml) compared to those from Bpn/3 mice (55.79 ± 11.32 pg/ml). There was also a notable disparity in the secretion of TNFβ where T cells from Bpn/3 mice (543.6 ± 175.8 pg/ml) showed a robust response versus the response of T cells from Bph/2 mice (20.64 ± 16.43 pg/ml), which was less than 10% than that of T cells from Bpn/3 mice. Interestingly, while T cells from Bph/2 mice had much lower induction of the signature Th2 cytokine, IL-4 (Bpn/3: 326.2 ± 59.18 pg/ml vs. Bph/2: 130.3 ± 21.58 pg/ml), there was little difference in IL-9 (Bpn/3: 12.9 ± 1.689 pg/ml vs. Bph/2: 19.06 ± 2.903 pg/ml), which is also associated with a Th2 response. We also found that Bph/2 mice had a diminished chemokine response as compared to T cells from Bpn/3 mice. Overall, the data suggest that polyclonally activated T cells from Bph/2 mice have a weaker cytokine/chemokine response as compared to T cells from Bpn/3 mice which may be due to an overall attenuated activation of T cells from Bph/2 mice.

Abstract P451: Effects of Perivascular Adipose Tissue on Arterial Stiffness in an Adiposity-Driven Hypertension Model: A Longitudinal Study

Perivascular adipose tissue (PVAT) is crucial for maintaining arterial function under healthy conditions. This research aims to test the hypothesis that the effect of PVAT on arterial stiffness is lessened as hypertension progresses in an animal model of adiposity-driven hypertension. We examined thoracic aorta samples from male Dahl Salt-Sensitive rats subjected to control (10% fat-CD) and high-fat (60% fat-HFD) diets for 16 and 24 weeks. Systolic blood pressure was significantly higher in HFD rats only at 24 weeks as compared to CD. Uniaxial mechanical tests were then conducted on aorta samples with and without PVAT. Arterial wall stiffness at 20% stretch (matching in vivo measures) was increased but not significantly higher in animals fed a HFD compared to those on a CD at 16 weeks but not 24 weeks. Surprisingly, the calculated stiffness of -PVAT samples significantly decreased by 24 weeks in both groups. Stiffness was reduced at both time points in +PVAT samples compared to -PVAT, but the beneficial effect of PVAT is diminished at 24 weeks. Because lower stretches may be important as hypertension progresses. We also measured stiffness at stretches &lt;10%. Here, the addition of PVAT lost all beneficial effects on stiffness at 24 weeks. These results suggest that while PVAT has a beneficial effect on arterial stiffness in adiposity-driven hypertension, its effectiveness decreases with aging.

Abstract P226: Sex-Dependent Effects of Perivascular Adipose Tissue on Arterial Stiffness in Hypertensive

Dillon McClintock, Department of Mechanical Engineering, Michigan State University, East Lansing, MI Sydney Bush, Department of Mechanical Engineering, Michigan State University, East Lansing, MI Lisa Sather, Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI Nathan Tykocki, Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI Adam Lauver, Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI Stephanie W Watts, Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI Sara Roccabianca, Department of Mechanical Engineering, Michigan State University, East Lansing, MI Perivascular adipose tissue (PVAT) plays a crucial role in arterial mechanics by significantly reducing arterial stiffness in the thoracic aorta in normotensive rats. This study aims to test the hypothesis that impact of PVAT on arterial stiffness is sex-dependent in an adiposity-driven hypertension rat model. Thoracic aorta from male and female Dahl Salt-Sensitive rats were fed control (10% fat-CD) and high-fat (60% fat-HFD) diets over 16 weeks. Uniaxial mechanical tests were then conducted on aorta samples with PVAT (+PVAT) and without PVAT (-PVAT). In -PVAT samples, arterial wall stiffness at 20% stretch (mimicking in vivo conditions), was higher in males compared to females on a HFD but not on a CD. HFD rats also had higher systolic blood pressures, but the increase was significant only in females. +PVAT samples’ stiffness was reduced by a 95% factor in all groups as compared to -PVAT samples. Furthermore, when including PVAT, the sex difference in the HF diet group was absent. These results suggest that PVAT has a beneficial effect that is preserved in this adiposity-driven hypertension animal model after 16 weeks on diet. Furthermore, remodeling of the arterial wall is more pronounced in male versus female rats and the inclusion of PVAT dampens this sex difference.

Animal models of pulmonary arterial hypertension associated with atrial septal defect

Pulmonary arterial hypertension (PAH) is a well-known complication of congenital heart disease (CHD). The lack of a satisfactory animal model for PAH associated with CHD (PAH-CHD) has limited progress in understanding the pathogenesis of PAH and the development of therapeutic agents. The development of a rat model for PAH associated with atrial septal defect (ASD) was achieved through atrial septal puncture and thermal ablation. Two and 4 weeks after modeling, hematoxylin and eosin staining showed that the vascular thickness, vascular thickness index, vascular area, and vascular area index in pulmonary arteries with an outer diameter of 50–300 μm in the PAH-ASD 2 and 4 weeks group were higher than those in the sham group (all P < 0.05). Alpha-smooth muscle actin (ɑ-SMA) staining showed that the medial thickness, medial thickness index, medial area, and medial area index in pulmonary arteries with an outer diameter of 50–300 µm at 2 and 4 weeks after modeling were significantly higher than those in the sham group (all P < 0.05). Additionally, mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) in the PAH-ASD 2 and 4 weeks groups were significantly higher than those in the sham group (both P < 0.05). Elastin van Gieson staining showed that the vascular obstruction score in the PAH-ASD 2 and 4 weeks group was significantly higher than that in the sham group (both P < 0.05). The PAH-ASD rats were successfully generated. These findings suggest that our model would be useful for further research into the pathogenesis, prevention, and treatment of PAH-ASD.

Myriad of factors involved in blood pressure control. Salt intake connects them all.

Long-lasting elevated blood pressure (BP), i.e. hypertension, is a major contributor to morbidity and mortality worldwide. As a multifactorial and systemic disease that involves multiple systems, hypertension remains a challenging disease to study. Models of hypertension are a basic source of knowledge to drive and support the discovery of the specific genetic, cellular, and molecular mechanisms underlying essential hypertension, as well as to discover and introduce new possible treatments to lower BP. Animal models of hypertension deliver a huge amount of information but it is important to choose the proper one for our scientific hypothesis. In this review, we discuss the physiological, and biochemical background of rodent models of hypertension through a systems approach and a myriad of mechanisms and pathways involved in blood pressure control. We also pay attention to how target organs and systems including the kidneys, vasculature, the sympathetic nervous system (SNS), and immunological system, interfere with each other, and their activity is differentially controlled by sodium delivery, which still remains a pivotal troublemaker.

Activation AMPK in Hypothalamic Paraventricular Nucleus Improves Renovascular Hypertension Through ERK1/2-NF-κB Pathway.

Hypertension is a globally prevalent disease, but the pathogenesis remains largely unclear. AMP-activated protein kinase (AMPK) is a nutrition-sensitive signal of cellular energy metabolism, which has a certain influence on the development of hypertension. Previously, we found a down-regulation of the phosphorylated (p-) form of AMPK, and the up-regulation of the angiotensin II type 1 receptor (AT1-R) and that of p-ERK1/2 in the hypothalamic paraventricular nucleus (PVN) of hypertensive rats. However, the exact mechanism underlying the relationship between AMPK and AT1-R in the PVN during hypertension remains unclear. Thus, we hypothesized that AMPK modulates AT1-R through the ERK1/2-NF-κB pathway in the PVN, thereby inhibiting sympathetic nerve activity and improving hypertension. To examine this hypothesis, we employed a renovascular hypertensive animal model developed via two-kidney, one-clip (2K1C) and sham-operated (SHAM). Artificial cerebrospinal fluid (aCSF), used as vehicle, or 5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide (AICAR, an AMPK activator, 60μg/day) was microinjected bilaterally in the PVN of these rats for 4weeks. In 2K1C rats, there an increase in systolic blood pressure (SBP) and circulating norepinephrine (NE). Also, the hypertensive rats had lowered expression of p-AMPK and p-AMPK/AMPK, elevated expression of p-ERK1/2, p-ERK1/2/ERK1/2 and AT1-R, increased NF-κB p65 activity in the PVN compared with the levels of these biomarkers in SHAM rats. Four weeks of bilateral PVN injection of AMPK activator AICAR, attenuated the NE level and SBP, increased the expression of p-AMPK and p-AMPK/AMPK, lessened the NF-κB p65 activity, decreased the expression of p-ERK1/2, p-ERK1/2/ERK1/2 and AT1-R in the PVN of 2K1C rats. Data from this study imply that the activation of AMPK within the PVN suppressed AT1-R expression through inhibiting the ERK1/2-NF-κB pathway, decreased the activity of the sympathetic nervous system, improved hypertension.

Anti-hypertensive effect and potential mechanism of gastrodia-uncaria granules based on network pharmacology and experimental validation.

Hypertension has become a major contributor to the morbidity and mortality of cardiovascular diseases worldwide. Despite the evidence of the anti-hypertensive effect of gastrodia-uncaria granules (GUG) in hypertensive patients, little is known about its potential therapeutic targets as well as the underlying mechanism. GUG components were sourced from TCMSP and HERB, with bioactive ingredients screened. Hypertension-related targets were gathered from DisGeNET, OMIM, GeneCards, CTD, and GEO. The STRING database constructed a protein-protein interaction network, visualized by Cytoscape 3.7.1. Core targets were analyzed via GO and KEGG using R package ClusterProfiler. Molecular docking with AutodockVina 1.2.2 revealed favorable binding affinities. In vivo studies on hypertensive mice and rats validated network pharmacology findings. GUG yielded 228 active ingredients and 1190 targets, intersecting with 373 hypertension-related genes. PPI network analysis identified five core genes: AKT1, TNF-α, GAPDH, IL-6, and ALB. Top enriched GO terms and KEGG pathways associated with the anti-hypertensive properties of GUG were documented. Molecular docking indicated stable binding of core components to targets. In vivo study showed that GUG could improve vascular relaxation, alleviate vascular remodeling, and lower blood pressure in hypertensive animal models possibly through inhibiting inflammatory factors such as AKT1, mTOR, and CCND1. Integrated network pharmacology and in vivo experiment showed that GUG may exert anti-hypertensive effects by inhibiting inflammation response, which provides some clues for understanding the effect and mechanisms of GUG in the treatment of hypertension.

Renal denervation: a key approach to hypertension and cardiovascular disease.

Sympathetic activation plays a critical role in the development of hypertension and cardiovascular disease, including heart failure and arrhythmias. Renal nerves contribute to the regulation of blood pressure and fluid volume through renal sympathetic efferent nerves, and to the modulation of sympathetic outflow through renal sensory afferent nerves. Previous studies including ours suggest that selective afferent renal denervation with preservation of efferent renal nerves can significantly decrease central sympathetic outflow in animal models of hypertension with renal damage. In Dahl salt-sensitive rats fed high salt diet from an early age, a model of hypertensive heart failure, this central sympathoinhibition by afferent renal denervation may attenuate the development of heart failure without significant blood pressure reduction. Accumulating clinical evidence supports the efficacy of renal denervation as an antihypertensive treatment. However, it remains important to clarify the appropriate indications and predictors of responders to renal denervation in the treatment of hypertension. Several clinical studies suggest beneficial effects of renal denervation in patients with heart disease, with or without hypertension, although most were not sham-controlled. In particular, some clinical studies have demonstrated that renal denervation reduces the incidence of atrial fibrillation or cardiovascular events even without a significant antihypertensive effect. It is essential to accumulate more insightful data in patients undergoing renal denervation, to establish the efficacy of renal denervation in patients with cardiovascular disease in the clinical setting, and to elucidate the therapeutic mechanisms of renal denervation and the renal nerves-linked pathophysiology of cardiovascular disease in basic research. This review outlines the effects of renal denervation on sympathetic activity and organ damage in animal models of hypertension and hypertensive heart failure, including our own data. Beyond the antihypertensive effects, the beneficial effects of renal denervation on cardiovascular disease are also discussed based on clinical studies. Several animal and clinical studies suggest the cardioprotective effects of renal denervation even in the absence of significant blood pressure reduction, probably due to its sympathoinhibitory effects.

Right ventricular diastolic adaptation to pressure overload in different rat strains.

Different rat strains are used in various animal models of pulmonary hypertension and right ventricular (RV) failure. No systematic assessment has been made to test differences in RV response to pressure overload between rat strains. We compared RV adaptation to pulmonary trunk banding (PTB) in Wistar (W), Sprague Dawley (SD), and Fischer344 (F) rats by hemodynamic profiling focusing on diastolic function. Age-matched male rat weanlings were randomized to sham surgery (W-sham, n = 5; SD-sham, n = 4; F-sham, n = 4) or PTB (W-PTB, n = 8; SD-PTB, n = 8; F-PTB, n = 8). RV function was evaluated after 5 weeks by echocardiography, cardiac MRI, and invasive pressure-volume measurements. PTB caused RV failure and increased RV systolic pressures four-fold in all three PTB groups compared with sham. W- and SD-PTB had a 2.4-fold increase in RV end-systolic volume index compared with sham, while F-PTB rats were less affected. Diastolic and right atrial impairment were evident by increased RV end-diastolic elastance, filling pressure, and E/e' in PTB rats compared with sham, again F-PTB the least affected. In conclusions, PTB caused RV failure with signs of diastolic dysfunction. Despite a similar increase in RV systolic pressure, F-PTB rats showed less RV dilatation and a more preserved diastolic function compared with W- and SD-PTB.

Cardioactive and Antihypertensive Properties of Tinospora crispa: An In vivo Approach

Tinospora crispa, a potent medicinal plant with multiple clinical indications, has a recorded history of ethnopharmaceutical use as an antihypertensive and has also been reported for its cardioactive properties. The antihypertensive and cardioactive properties of the plant were investigated in two different animal models of hypertension (ethanol-induced and digoxin-induced). In both models, the plant’s ethanolic extract was observed to exert a dose-dependent effect. Furthermore, treatment with the ethanolic extract resulted in no undesirable changes in liver and kidney function parameters such as serum SGOT, SGPT and creatinine levels. The ethanolic extract of the plant may, therefore, be considered safe and effective for the treatment of hypertension, although further extensive research into this is warranted. Dhaka Univ. J. Pharm. Sci. 23(1): 1-6, 2024 (June)

798-P: Potential Cardioprotective Effects of HM15275, a Novel, Long-Acting GLP-1/GIP/GCG Triple Agonist, in Animal Models of Hypertension

798-P: Potential Cardioprotective Effects of HM15275, a Novel, Long-Acting GLP-1/GIP/GCG Triple Agonist, in Animal Models of Hypertension

Targeting IL-11 to reduce fibrocyte circulation and lung accumulation in animal models of pulmonary hypertension-associated lung fibrosis.

IL-11 is a member of the IL-6 family of cytokine initially considered as haematopoietic and cytoprotective factor. Recent evidence indicates that IL-11 promotes lung fibrosis and pulmonary hypertension in animal models and is elevated in lung tissue of patients with pulmonary fibrosis and pulmonary hypertension. Fibrocytes are bone marrow-derived circulating cells that participate in lung fibrosis and pulmonary hypertension, but the role of IL-11 on fibrocytes is unknown. We investigated the role of IL-11 system on fibrocyte activation in different in vitro and in vivo models of lung fibrosis associated with pulmonary hypertension. Human fibrocytes were isolated from peripheral blood of six healthy donors. Recombinant human (rh)-IL-11 and soluble rh-IL-11 receptor, α subunit (IL-11Rα) were used to stimulated fibrocytes in vitro to measure:- cell migration in a chemotactic migration chamber, fibrocyte to endothelial cell adhesion in a microscope-flow chamber and fibrocyte to myofibroblast transition. Mouse lung fibrosis and pulmonary hypertension was induced using either IL-11 (s.c.) or bleomycin (intra-tracheal), while in the rat monocrotaline (intra-tracheal) was used. In vivo siRNA-IL-11 was administered to suppress IL-11 in vivo. RhIL-11 and soluble rhIL-11Rα promote fibrocyte migration, endothelial cell adhesion and myofibroblast transition. Subcutaneous (s.c.) IL-11 infusion elevates blood, bronchoalveolar and lung tissue fibrocytes. SiRNA-IL-11 transfection in bleomycin and monocrotaline animal models reduces blood and lung tissue fibrocytes and reduces serum CXCL12 and CXCL12/CXCR4 lung expression. Targeting IL-11 reduces fibrocyte circulation and lung accumulation in animal models of pulmonary hypertension-associated lung fibrosis.

Disrupted BMP-9 Signaling Impairs Pulmonary Vascular Integrity in Hepatopulmonary Syndrome.

Rationale: Hepatopulmonary syndrome (HPS) is a severe complication of liver diseases characterized by abnormal dilation of pulmonary vessels, resulting in impaired oxygenation. Recent research highlights the pivotal role of liver-produced BMP-9 (bone morphogenetic protein-9) in maintaining pulmonary vascular integrity. Objectives: This study aimed to investigate the involvement of BMP-9 in human and experimental HPS. Methods: Circulating BMP-9 levels were measured in 63 healthy control subjects and 203 patients with cirrhosis with or without HPS. Two animal models of portal hypertension were employed: common bile duct ligation with cirrhosis and long-term partial portal vein ligation without cirrhosis. Additionally, the therapeutic effect of low-dose BMP activator FK506 was investigated, and the pulmonary vascular phenotype of BMP-9-knockout rats was analyzed. Measurements and Main Results: Patients with HPS related to compensated cirrhosis exhibited lower levels of circulating BMP-9 compared with patients without HPS. Patients with severe cirrhosis exhibited consistently low levels of BMP-9. HPS characteristics were observed in animal models, including intrapulmonary vascular dilations and an increase in the alveolar-arterial gradient. HPS development in both rat models correlated with reduced intrahepatic BMP-9 expression, decreased circulating BMP-9 level and activity, and impaired pulmonary BMP-9 endothelial pathway. Daily treatment with FK506 for 2 weeks restored the BMP pathway in the lungs, alleviating intrapulmonary vascular dilations and improving gas exchange impairment. Furthermore, BMP-9-knockout rats displayed a pulmonary HPS phenotype, supporting its role in disease progression. Conclusions: The study findings suggest that portal hypertension-induced loss of BMP-9 signaling contributes to HPS development.

An Autotaxin-Induced Ocular Hypertension Mouse Model Reflecting Physiological Aqueous Biomarker.

Animal models of ocular hypertension (OH) have been developed to understand the pathogenesis of glaucoma and facilitate drug discovery. However, many of these models are fraught with issues, including severe intraocular inflammation and technical challenges. Lysophosphatidic acid (LPA) is implicated in trabecular meshwork fibrosis and increased resistance of aqueous outflow, factors that contribute to high intraocular pressure (IOP) in human open-angle glaucoma. We aimed to elevate IOP by increasing expression of the LPA-producing enzyme autotaxin (ATX) in mouse eyes. Tamoxifen-inducible ATX transgenic mice were developed. Tamoxifen was administered to six- to eight-week-old mice via eye drops to achieve ATX overexpression in the eye. IOP and retinal thickness were measured over time, and retinal flat-mount were evaluated to count retinal ganglion cells (RGCs) loss after three months. Persistent elevation of ATX expression in mouse eyes was confirmed through immunohistochemistry and LysoPLD activity measurement. ATX Tg mice exhibited significantly increased IOP for nearly two months following tamoxifen treatment, with no anterior segment changes or inflammation. Immunohistochemical analysis revealed enhanced expression of extracellular matrix near the angle after two weeks and three months of ATX induction. This correlated with reduced outflow facility, indicating that sustained ATX overexpression induces angle fibrosis, elevating IOP. Although inner retinal layer thickness remained stable, peripheral retina showed a notable reduction in RGC cell count. These findings confirm the successful creation of an open-angle OH mouse model, in which ATX expression in the eye prompts fibrosis near the angle and maintains elevated IOP over extended periods.

Effect of hydrogen inhalation on cardiovascular and interstitial components of pulmonary hypertension in rats

Hydrogen is known to have selective antioxidant properties. It binds highly reactive hydroxyl radicals. The pathogenesis of the monocrotaline animal model of pulmonary hypertension is associated with oxidative stress and leads to all the symptoms of pulmonary hypertension (PH) and interstitial lung disease (ILD) associated with hypertension.The aim of this work was to study the effect of 4% hydrogen inhalations on the symptoms of PH and ILD in rats.Methods. To model monocrotaline-induced pulmonary hypertension (MCT-PH), two groups of animals received a single subcutaneous injection of monocrotaline (MCT) on day 1. The control group was injected subcutaneously with MCT solvent only. The animals receiving MCT were further divided into 2 subgroups. Subgroup 1 rats breathed room air and subgroup 2 rats breathed a mixture of room air and 4% hydrogen. The regular inhalations continued until day 21. On day 21, hemodynamic parameters were measured under urethane anesthesia, the heart and its components and the lungs were weighed, and lung tissue was preserved for morphological study.Results. The inhalation had no effect on the main cardiovascular symptoms of PH, but a positive effect on the state of the connective tissue of the lungs affected by PH was shown. The mast cell response was reduced both quantitatively and functionally. There was a decrease in tryptase expression by mast cells, with predominance of the forms without signs of degranulation. TGF-β secretion was also significantly reduced and visualized by immunopositive cells in alveolar cellular structures and vessel walls.Conclusion. Inhalation of 4% hydrogen reduces inflammation and fibrosis of lung tissue during the development of MCT-PH.