Adrenomedullin: Not Just Another Gastrointestinal Peptide

The value of midregional proadrenomedullin to predict mortality in intensive care unit

AIM

This study explores the value of midregional proadrenomedullin (mr-proADM), C-reactive protein (CRP), procalcitonin (PCT), and presepsin (PSP) in predicting mortality, considering both their absolute values at different time points and their dynamic kinetics.

METHODS

We conducted a retrospective observational study including all consecutive adult ICU admissions. Biomarkers were measured at admission (T0), day 3 (T3), and day 5 (T5). We assessed absolute values, relative variations, and categorized changes (≥50 % increase or decrease).

RESULTS

A total of 99 patients were included. mr-proADM at T3 had the highest predictive value for ICU mortality (AUC = 0.77), followed by PSP at T3 (AUC = 0.70). Cox regression identified mr-proADM at T3 as an independent predictor of mortality (HR: 1.16, p < 0.001), with a ≥ 50 % increase in mr-proADM from T0 to T3 significantly associated with mortality risk (HR: 4.15, p < 0.001). In patients with low baseline mr-proADM levels, a ≥ 50 % increase at T3 was significantly associated with mortality (HR: 4.43, p = 0.04), while in those with high baseline levels, the absolute value at T3 was more predictive.

CONCLUSION

Our findings suggest that mr-proADM at T3 is the most informative biomarker for predicting ICU mortality, with its absolute value and dynamic increase providing valuable prognostic insights. Importantly, stratified analysis highlights that different risk stratification approaches may be necessary based on baseline mr-proADM levels.

Hypoxia-inducible factor and cellular senescence in pulmonary aging and disease

Cellular senescence and hypoxia-inducible factor (HIF) signaling are crucial in pulmonary aging and age-related lung diseases such as chronic obstructive pulmonary disease idiopathic pulmonary fibrosis and lung cancer. HIF plays a pivotal role in cellular adaptation to hypoxia, regulating processes like angiogenesis, metabolism, and inflammation. Meanwhile, cellular senescence leads to irreversible cell cycle arrest, triggering the senescence-associated secretory phenotype which contributes to chronic inflammation, tissue remodeling, and fibrosis. Dysregulation of these pathways accelerates lung aging and disease progression by promoting oxidative stress, mitochondrial dysfunction, and epigenetic alterations. Recent studies indicate that HIF and senescence interact at multiple levels, where HIF can both induce and suppress senescence, depending on cellular conditions. While transient HIF activation supports tissue repair and stress resistance, chronic dysregulation exacerbates pulmonary pathologies. Furthermore, emerging evidence suggests that targeting HIF and senescence pathways could offer new therapeutic strategies to mitigate age-related lung diseases. This review explores the intricate crosstalk between these mechanisms, shedding light on how their interplay influences pulmonary aging and disease progression. Additionally, we discuss potential interventions, including senolytic therapies and HIF modulators, that could enhance lung health and longevity.

Distinguishing exocrine pancreas disease-associated diabetes from type 2 diabetes based on anthropometric and metabolic parameters

BACKGROUND

Adult-onset diabetes is most often considered to be type 2 diabetes. However, other types of diabetes can develop in adults, including exocrine pancreas disease-associated diabetes, also called type 3c diabetes. Differential diagnosis between these types of diabetes still remains a diagnostic challenge.

AIM

To define anthropometric and laboratory markers that will allow for early diagnosis of pancreatic disease-associated diabetes.

METHODS

The study group included 44 patients with pancreatogenic diabetes (26 with pancreatic cancer and 18 with chronic pancreatitis), while the control group consisted of 35 patients with type 2 diabetes. We analyzed several parameters, including sex, age, body mass index (BMI), fasting plasma glucose, fasting C-peptide and insulin with homeostasis model assessment of insulin resistance (HOMA-IR) index calculation, adrenomedullin, adiponectin and creatinine levels with epidermal growth factor receptor (eGFR) calculation. We also developed an equation, termed type 3c diabetes index, which utilized BMI, fasting insulin and adrenomedullin levels, and eGFR to better identify patients with type 3c diabetes.

RESULTS

Compared to patients with type 2 diabetes, patients with pancreatogenic diabetes had significantly lower BMI (25.11 ± 4.87 kg/m2 vs 30.83 ± 5.21 kg/m2), fasting C-peptide (0.81 ± 0.42 nmol/L vs 1.71 ± 0.80 nmol/L), insulin (76.81 ± 63.34 pmol/L vs 233.19 ± 164.51 pmol/L) and HOMA-IR index, despite similar fasting plasma glucose levels. Patients with pancreatogenic diabetes also had lower adrenomedullin levels (0.41 ± 0.25 ng/mL vs 0.63 ± 0.38 ng/mL) but higher adiponectin levels (13.08 ± 7.20 μg/mL vs 8.28 ± 4.01 μg/mL) and eGFR levels (100.53 ± 21.60 mL/min/1.73 m2 vs 85.14 ± 19.24 mL/min/1.73 m2). Finally, patients with pancreatogenic diabetes had significantly lower Type 3c diabetes index values.

CONCLUSION

Patients with pancreatogenic diabetes differ from patients with type 2 diabetes in anthropometric and laboratory parameters. The type 3c diabetes index had the highest discriminating value, above any single parameter.

Adrenomedullin-loaded Gelatin Methacryloyl Hydrogel Promotes Endogenous Dental Pulp Regeneration: An In Vitro and In Vivo Study

INTRODUCTION

To prepare a gelatin methacryloyl (GelMA) hydrogel scaffold embedded with adrenomedullin (ADM) and investigate its impact and underlying mechanisms in endogenous pulp regeneration.

METHODS

ADM was evenly distributed within the GelMA hydrogel through a simple and conventional physical mixing technique. The scaffold underwent characterization via scanning electron microscopy, alongside assessments of swelling, degradation, and release properties. Biocompatibility was evaluated using cytoskeletal and live-dead staining techniques. The hydrogel's influence on dental pulp stem cells' proliferation, migration, and differentiation was assessed with CCK-8 assays, Transwell assays, and alizarin red and alkaline phosphatase staining. Transcriptomics provided insights into potential mechanisms. The angiogenic effects on umbilical vein endothelial cells were examined using scratch and tube formation assays. In vivo, the composite hydrogel's regenerative capacity was tested in a rat model of pulp regeneration. Statistical analysis involved Student's t-test and one-way analysis of variance, with significance set at P < .05.

RESULTS

The ADM-loaded GelMA (GelMA@ADM) hydrogel displayed a porous architecture under electron microscopy conducive to cell adhesion and demonstrated excellent biocompatibility. In vitro experiments showed that GelMA@ADM significantly boosted dental pulp stem cells' migration, proliferation, and differentiation, and enhanced the angiogenic activity of umbilical vein endothelial cells after one week of treatment. Corresponding in vivo experiments revealed that GelMA@ADM facilitated the formation of new vascularized pulp tissue after 2 weeks of treatment.

CONCLUSIONS

The GelMA@ADM hydrogel effectively promotes dental pulp stem cells' proliferation and differentiation, augments vascularization by umbilical vein endothelial cells, and fosters the creation of new vascularized pulp tissue. These findings underscore the potential of GelMA@ADM hydrogel for endogenous pulp regeneration.

Evidence of Involvement of the Calcitonin Gene-Related Peptide in Restless Legs Syndrome

BACKGROUND

Restless legs syndrome (RLS) is a common sensory-motor disorder characterized by an urge to move the legs, often with unpleasant sensations, particularly during rest. Current treatments include iron supplementation, dopamine agonists, and opioids, but new therapeutic approaches are needed. The dysfunction of the A11 nucleus, which modulates dopaminergic transmission to the spinal cord, is thought to play a role in RLS pathophysiology. Calcitonin gene-related peptide (CGRP), which is involved in pain modulation, may interact with A11 pathways, suggesting a role in RLS.

OBJECTIVES

This study aimed to assess the involvement of CGRP in RLS by determining if CGRP-related proteins are overexpressed in RLS patients.

METHODS

A cross-sectional study was conducted with 17 drug-free RLS patients (mean age 55.8 years) and 17 age- and gender-matched controls. Serum samples were analyzed using liquid chromatography-parallel reaction monitoring-tandem mass spectrometry (LC-PRM-MS/MS) to identify and quantify CGRP-related proteins. Principal component analysis (PCA) was used to differentiate between groups.

RESULTS

PCA showed clear differentiation between RLS and control groups. Among 13 identified CGRP-related proteins, 10 were dysregulated in RLS patients: 8 were upregulated, and 2 were downregulated, among them notable proteins such as S100A12, ADM, SRSF6, and ADM2.

CONCLUSIONS

This study indicates the significant involvement of CGRP and related proteins in RLS. This suggests these proteins may play roles in various aspects of the disorder. Further research is required to validate these findings and explore their clinical implications, including development of new treatment options that specifically address CGRP pathways. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Extracellular matrix substrates differentially influence enteric glial cell homeostasis and immune reactivity

Introduction

Enteric glial cells are important players in the control of motility, intestinal barrier integrity and inflammation. During inflammation, they switch into a reactive phenotype enabling them to release inflammatory mediators, thereby shaping the inflammatory environment. While a plethora of well-established in vivo models exist, cell culture models necessary to decipher the mechanistic pathways of enteric glial reactivity are less well standardized. In particular, the composition of extracellular matrices (ECM) can massively affect the experimental outcome. Considering the growing number of studies involving primary enteric glial cells, a better understanding of their homeostatic and inflammatory in vitro culture conditions is needed.

Methods

We examined the impact of different ECMs on enteric glial culture purity, network morphology and immune responsiveness. Therefore, we used immunofluorescence and brightfield microscopy, as well as 3' bulk mRNA sequencing. Additionally, we compared cultured cells with in vivo enteric glial transcriptomes isolated from Sox10iCreERT2Rpl22HA/+ mice.

Results

We identified Matrigel and laminin as superior over other coatings, including poly-L-ornithine, different lysines, collagens, and fibronectin, gaining the highest enteric glial purity and most extended glial networks expressing connexin-43 hemichannels allowing intercellular communication. Transcriptional analysis revealed strong similarities between enteric glia on Matrigel and laminin with enrichment of gene sets supporting neuronal differentiation, while cells on poly-L-ornithine showed enrichment related to cell proliferation. Comparing cultured and in vivo enteric glial transcriptomes revealed a 50% overlap independent of the used coating substrates. Inflammatory activation of enteric glia by IL-1β treatment showed distinct coating-dependent gene expression signatures, with an enrichment of genes related to myeloid and epithelial cell differentiation on Matrigel and laminin coatings, while poly-L-ornithine induced more gene sets related to lymphocyte differentiation.

Discussion

Together, changes in morphology, differentiation and immune activation of primary enteric glial cells proved a strong effect of the ECM. We identified Matrigel and laminin as pre-eminent substrates for murine enteric glial cultures. These new insights will help to standardize and improve enteric glial culture quality and reproducibility between in vitro studies in the future, allowing a better comparison of their functional role in enteric neuroinflammation.

Grimm S, Coarfa C, Theis F, Simon LM, Shivanna B. Leveraging Integrated RNA Sequencing to Decipher Adrenomedullin's Protective Mechanisms in Experimental Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic lung disease commonly affecting premature infants, with limited therapeutic options and increased long-term consequences. Adrenomedullin (Adm), a proangiogenic peptide hormone, has been found to protect rodents against experimental BPD. This study aims to elucidate the molecular and cellular mechanisms through which Adm influences BPD pathogenesis using a lipopolysaccharide (LPS)-induced model of experimental BPD in mice. Bulk RNA sequencing of Adm-sufficient (wild-type or Adm+/+) and Adm-haplodeficient (Adm+/-) mice lungs, integrated with single-cell RNA sequencing data, revealed distinct gene expression patterns and cell type alterations associated with Adm deficiency and LPS exposure. Notably, computational integration with cell atlas data revealed that Adm-haplodeficient mouse lungs exhibited gene expression signatures characteristic of increased inflammation, natural killer (NK) cell frequency, and decreased endothelial cell and type II pneumocyte frequency. Furthermore, in silico human BPD patient data analysis supported our cell type frequency finding, highlighting elevated NK cells in BPD infants. These results underscore the protective role of Adm in experimental BPD and emphasize that it is a potential therapeutic target for BPD infants with an inflammatory phenotype.

Fresh Parent's Own Milk for Preterm Infants: Barriers and Future Opportunities

While direct at-the-breast feeding is biologically optimal, Neonatal Intensive Care Unit (NICU) admission due to infant immaturity or illness often necessitates the expression and storage of parent's milk. The provision of freshly expressed (never stored) parent's own milk to preterm infants is not widely prioritized, and this article provides an exploration of NICU practices and their implications for feeding premature or ill infants with parent's own milk. In this article, we discuss the potential biological benefits of fresh parent's own milk, highlighting its dynamic components and the changes incurred during storage. Research suggests that fresh milk may offer health advantages over stored milk. The authors advocate for further research, emphasizing the need for standardized definitions. Research is needed on the biological impact of fresh milk, both short- and long-term, as well as defining and understanding healthcare economics when using fresh milk.

Mechanisms and treatment of obesity-related hypertension-Part 1: Mechanisms

The prevalence of obesity has tripled over the past five decades. Obesity, especially visceral obesity, is closely related to hypertension, increasing the risk of primary (essential) hypertension by 65%-75%. Hypertension is a major risk factor for cardiovascular disease, the leading cause of death worldwide, and its prevalence is rapidly increasing following the pandemic rise in obesity. Although the causal relationship between obesity and high blood pressure (BP) is well established, the detailed mechanisms for such association are still under research. For more than 30 years sympathetic nervous system (SNS) and kidney sodium reabsorption activation, secondary to insulin resistance and compensatory hyperinsulinemia, have been considered as primary mediators of elevated BP in obesity. However, experimental and clinical data show that severe insulin resistance and hyperinsulinemia can occur in the absence of elevated BP, challenging the causal relationship between insulin resistance and hyperinsulinemia as the key factor linking obesity to hypertension. The purpose of Part 1 of this review is to summarize the available data on recently emerging mechanisms believed to contribute to obesity-related hypertension through increased sodium reabsorption and volume expansion, such as: physical compression of the kidney by perirenal/intrarenal fat and overactivation of the systemic/renal SNS and the renin-angiotensin-aldosterone system. The role of hyperleptinemia, impaired chemoreceptor and baroreceptor reflexes, and increased perivascular fat is also discussed. Specifically targeting these mechanisms may pave the way for a new therapeutic intervention in the treatment of obesity-related hypertension in the context of 'precision medicine' principles, which will be discussed in Part 2.

Potential angiogenic biomarkers in hereditary hemorrhagic telangiectasia and other vascular diseases

Biomarkers are new tools framed in precision and personalized medicine. Hereditary hemorrhagic telangiectasia (HHT) is a rare genetic vascular disease with disturbances in the angiogenic pathways. Descriptive evidence supports that some angiogenesis-related molecules are differently detected in HHT patients compared to healthy subjects. These molecules are also related to diagnosis, prognosis, complications and therapy monitoring in other common vascular diseases. Despite the need for improving knowledge before applying them in daily clinical practice, there are good candidates to be considered as potential biomarkers in HHT and other vascular diseases. In the present review, the authors aim to summarize and discuss current evidence regarding the main putative angiogenic biomarkers by describing the biological role of each biomarker, the evidence related to HHT and their potential use in this and other common vascular diseases from a clinical point-of-view.

Animal models of the placenta accreta spectrum: current status and further perspectives

Placenta accreta spectrum disorder (PAS) is a kind of disease of placentation defined as abnormal trophoblast invasion of part or all of the placenta into the myometrium, even penetrating the uterus. Decidual deficiency, abnormal vascular remodeling in the maternal-fetal interface, and excessive invasion by extravillous trophoblast (EVT) cells contribute to its onset. However, the mechanisms and signaling pathways underlying such phenotypes are not fully understood, partly due to the lack of suitable experimental animal models. Appropriate animal models will facilitate the comprehensive and systematic elucidation of the pathogenesis of PAS. Due to the remarkably similar functional placental villous units and hemochorial placentation to humans, the current animal models of PAS are based on mice. There are various mouse models induced by uterine surgery to simulate different phenotypes of PAS, such as excessive invasion of EVT or immune disturbance at the maternal-fetal interface, which could define the pathological mechanism of PAS from the perspective of the "soil." Additionally, genetically modified mouse models could be used to study PAS, which is helpful to exploring the pathogenesis of PAS from the perspectives of both "soil" and "seed," respectively. This review details early placental development in mice, with a focus on the approaches of PAS modeling. Additionally, the strengths, limitations and the applicability of each strategy and further perspectives are summarized to provide the theoretical foundation for researchers to select appropriate animal models for various research purposes. This will help better determine the pathogenesis of PAS and even promote possible therapy.

Adrenomedullin Improves Hypertension and Vascular Remodeling partly through the Receptor-Mediated AMPK Pathway in Rats with Obesity-Related Hypertension

Adrenomedullin (ADM) is a novel cardiovascular peptide with anti-inflammatory and antioxidant properties. Chronic inflammation, oxidative stress and calcification play pivotal roles in the pathogenesis of vascular dysfunction in obesity-related hypertension (OH). Our study aimed to explore the effects of ADM on the vascular inflammation, oxidative stress and calcification in rats with OH. Eight-week-old Sprague Dawley male rats were fed with either a Control diet or a high fat diet (HFD) for 28 weeks. Next, the OH rats were randomly subdivided into two groups as follows: (1) HFD control group, and (2) HFD with ADM. A 4-week treatment with ADM (7.2 μg/kg/day, ip) not only improved hypertension and vascular remodeling, but also inhibited vascular inflammation, oxidative stress and calcification in aorta of rats with OH. In vitro experiments, ADM (10 nM) in A7r5 cells (rat thoracic aorta smooth muscle cells) attenuated palmitic acid (PA, 200 μM) or angiotensin II (Ang II, 10 nM) alone or their combination treatment-induced inflammation, oxidative stress and calcification, which were effectively inhibited by the ADM receptor antagonist ADM22-52 and AMP-activated protein kinase (AMPK) inhibitor Compound C, respectively. Moreover, ADM treatment significantly inhibited Ang II type 1 receptor (AT1R) protein expression in aorta of rats with OH or in PA-treated A7r5 cells. ADM improved hypertension, vascular remodeling and arterial stiffness, and attenuated inflammation, oxidative stress and calcification in OH state partially via receptor-mediated AMPK pathway. The results also raise the possibility that ADM will be considered for improving hypertension and vascular damage in patients with OH.

Effects of Adrenomedullin on Atrial Electrophysiology and Pulmonary Vein Arrhythmogenesis

Adrenomedullin, a peptide with vasodilatory, natriuretic, and diuretic effects, may be a novel agent for treating heart failure. Heart failure is associated with an increased risk of atrial fibrillation (AF), but the effects of adrenomedullin on atrial arrhythmogenesis remain unclear. This study investigated whether adrenomedullin modulates the electrophysiology of the atria (AF substrate) or pulmonary vein (PV; AF trigger) arrhythmogenesis. Conventional microelectrode or whole-cell patch clamps were used to study the effects of adrenomedullin (10, 30, and 100 pg/mL) on the electrical activity, mechanical response, and ionic currents of isolated rabbit PV and sinoatrial node tissue preparations and single PV cardiomyocytes. At 30 and 100 pg/mL, adrenomedullin significantly reduced the spontaneous beating rate of the PVs from 2.0 ± 0.4 to 1.3 ± 0.5 and 1.1 ± 0.5 Hz (reductions of 32.9% ± 7.1% and 44.9 ± 8.4%), respectively, and reduced PV diastolic tension by 12.8% ± 4.1% and 14.5% ± 4.1%, respectively. By contrast, adrenomedullin did not affect sinoatrial node beating. In the presence of L-NAME (a nitric oxide synthesis inhibitor, 100 μM), adrenomedullin (30 pg/mL) did not affect the spontaneous beating rate or diastolic tension of the PVs. In the single-cell experiments, adrenomedullin (30 pg/mL) significantly reduced the L-type calcium current (I_Ca-L) and reverse-mode current of the sodium-calcium exchanger (NCX). Adrenomedullin reduces spontaneous PV activity and PV diastolic tension by reducing I_Ca-L and NCX current and thus may be useful for treating atrial tachyarrhythmia.

Proteomics of the phase angle: Results from the population-based KORA S4 study

BACKGROUND & AIMS

The phase angle (PhA) measured with bioelectrical impedance analysis is considered to reflect the interrelated components body cell mass and fluid distribution based on technical and physical aspects of the PhA measurement. However, the biomedical meaning of the PhA remains vague. Previous studies mainly assessed associations of the PhA with numerous diseases and health outcomes, but few connected protein markers to the PhA. To broaden our understanding of the biomedical background of the PhA, we aimed to explore a proteomics profile associated with the PhA and related biological factors.

METHODS

The study sample encompassed 1484 participants (725 women and 759 men) aged 55-74 years from the population-based Cooperative Health Research in the Region of Augsburg (KORA) S4 study. Proteomics measurements were performed with a proximity extension assay. We employed boosting with stability selection to establish a set of markers that was strongly associated with the PhA from a group of 233 plasma protein markers. We integrated the selected protein markers into a network and enrichment analysis to identify gene ontology (GO) terms significantly overrepresented for the selected PhA protein markers.

RESULTS

Boosting with stability selection identified seven protein markers that were strongly and independently associated with the PhA: N-terminal prohormone brain natriuretic peptide (NT-proBNP), insulin-like growth factor-binding protein 2 (IGFBP2), adrenomedullin (ADM), myoglobin (MB), matrix metalloproteinase-9 (MMP9), protein-glutamine gamma-glutamyltransferase 2 (TGM2), and fractalkine (CX3CL1) [beta coefficient per 1 standard deviation increase in normalized protein expression values on a log 2 scale (95% confidence interval): -0.12 (-0.15, -0.08), -0.13 (-0.17, -0.09), -0.14 (-0.18, -0.10), 0.10 (0.07, 0.14), 0.07 (0.04, 0.10), 0.08 (0.05, 0.11), -0.06 (-0.10, -0.03), respectively]. According to the enrichment analysis, this protein profile was significantly overrepresented in the following top five GO terms: positive regulation of cell population proliferation (p-value: 1.32E-04), extracellular space (p-value: 1.34E-04), anatomical structure formation involved in morphogenesis (p-value: 2.92E-04), regulation of multicellular organismal development (p-value: 5.72E-04), and metal ion homeostasis (p-value: 8.86E-04).

CONCLUSION

Implementing a proteomics approach, we identified six new protein markers strongly associated with the PhA and confirmed that NT-proBNP is a key PhA marker. The main biological processes that were related to this PhA's protein profile are involved in regulating the amount and growth of cells, reinforcing, from a biomedical perspective, the current technical-based consensus of the PhA to reflect body cell mass.

Biomarkers of Volume Overload and Edema in Heart Failure With Reduced Ejection Fraction

From a pathogenetic point of view, heart failure (HF) is characterized by the activation of several neurohumoral pathways with a role in maintaining the cardiac output and the adequate perfusion pressure in target organs and tissues. Decreased cardiac output in HF with reduced ejection fraction causes activation of the sympathetic nervous system, the renin angiotensin aldosterone system, arginine-vasopressin system, natriuretic peptides, and endothelin, all of which cause water and salt retention in the body. As a result, patients will present clinically as the main symptoms: dyspnea and peripheral edema caused by fluid redistribution to the lungs and/or by fluid overload. By studying these pathophysiological mechanisms, biomarkers with a prognostic and therapeutic role in the management of edema were identified in patients with HF with low ejection fraction. This review aims to summarize the current data from the specialty literature of such biomarkers with a role in the pathogenesis of edema in HF with low ejection fraction. These biomarkers may be the basis for risk stratification and the development of new therapeutic means in the treatment of edema in these patients.

Endoglin and Activin Receptor-like Kinase 1 (Alk1) Modify Adrenomedullin Expression in an Organ-Specific Manner in Mice

Simple Summary

Hereditary hemorrhagic telangiectasia (HHT) is called a rare disease because it affects relatively few people. It is characterized by malformations in some blood vessels and usually results in profuse nose bleedings. In a recent article, we found that these patients have higher levels of adrenomedullin (AM), a molecule with cardiovascular activities, than healthy people. Thus we wanted to know whether the mutations that cause the HHT disease are directly responsible for these higher levels of AM. To investigate this issue, we used mutant mice, which express lower levels of the genes involved in the disease (called Eng and Acvrl1), and measured how much AM was found in different tissues. Although we expected a higher amount of AM in all organs, that was not the case. Some organs showed no variation, some had lower levels of AM than normal mice (fat, skin, and adrenals), and others had a higher expression (cerebellum and colon). Interestingly, our results suggest that these genes and the related molecule BMP-9 may have novel functions, which have not been yet investigated, which may shed more light on the physiopathology of HHT.

Abstract

Hereditary hemorrhagic telangiectasia (HHT) is a rare disease characterized by vascular malformations and profuse bleeding. The disease is caused by mutations in the components of the BMP-9 receptor: endoglin (ENG) and activin receptor-like kinase 1 (ACVRL1) genes. Recently, we reported that HHT patients expressed higher serum levels of adrenomedullin (AM) than healthy volunteers; thus, we studied the expression of AM (by enzyme immunoassay, qRT-PCR, immunohistochemistry, and Western blotting) in mice deficient in either one of the receptor components to investigate whether these defects may be the cause of that elevated AM in patients. We found that AM expression is not affected by these mutations in a consistent pattern. On the contrary, in some organs (blood, lungs, stomach, pancreas, heart, kidneys, ovaries, brain cortex, hippocampus, foot skin, and microvessels), there were no significant changes, whereas in others we found either a reduced expression (fat, skin, and adrenals) or an enhanced production of AM (cerebellum and colon). These results contradict our initial hypothesis that the increased AM expression found in HHT patients may be due directly to the mutations, but open intriguing questions about the potential phenotypic manifestations of Eng and Acvrl1 mutants that have not yet been studied and that may offer, in the future, a new focus for research on HHT.