Infusion of adrenomedullin improves acute myocarditis via attenuation of myocardial inflammation and edema

Sustained Activation of CLR/RAMP Receptors by Gel-Forming Agonists

Background: Adrenomedullin (ADM), adrenomedullin 2 (ADM2), and CGRP family peptides are important regulators of vascular vasotone and integrity, neurotransmission, and fetoplacental development. These peptides signal through CLR/RAMP1, 2, and 3 receptors, and protect against endothelial dysfunction in disease models. As such, CLR/RAMP receptor agonists are considered important therapeutic candidates for various diseases. Methods and Results: Based on the screening of a series of palmitoylated chimeric ADM/ADM2 analogs, we demonstrated a combination of lipidation and accommodating motifs at the hinge region of select peptides is important for gaining an enhanced receptor-activation activity and improved stimulatory effects on the proliferation and survival of human lymphatic endothelial cells when compared to wild-type peptides. In addition, by serendipity, we found that select palmitoylated analogs self-assemble to form liquid gels, and subcutaneous administration of an analog gel led to the sustained presence of the peptide in the circulation for >2 days. Consistently, subcutaneous injection of the analog gel significantly reduced the blood pressure in SHR rats and increased vasodilation in the hindlimbs of adult rats for days. Conclusions: Together, these data suggest gel-forming adrenomedullin analogs may represent promising candidates for the treatment of various life-threatening endothelial dysfunction-associated diseases such as treatment-resistant hypertension and preeclampsia, which are in urgent need of an effective drug.

Effect of Bone Marrow Mesenchymal Stem Cell Sheets on Skin Capillary Parameters in a diabetic wound model: A Novel Preliminary Study

Background

Treatment with BMMSCs has anti-inflammatory, tissue regenerative, angiogenic, and immune-stimulating effects. When using as sheets or accumulate, BMMSCs causes the development of neoangiogenesis in damaged skin tissue. Diabetes, a metabolic disorder, can negatively affect many physiological functions, including the process of skin injury repair. This adverse impact may increase the risk of skin surgery. RSF is commonly used in reconstructive surgery. The terminal part of the RSF is often affected by necrosis because of impaired blood flow, which is exacerbated in diabetes. This study investigated the effect of stem cells, applied as accumulated or cell sheets, along with RSF surgery on skin capillaries in STZ-induced diabetic rats.

Methods

Thirty male Wistar rats were divided into three groups (n = 10): diabetes-RSF control, diabetes-RSF local applied stem cells (loc-BMMSCs), diabetes-RSF applied stem cells as accumulated or cell sheets (ac-BMMSCs). Two weeks after the STZ injection, RSF surgery and stem cell therapy (6 × 109) were carried out (day zero). Furthermore, stereological methods were used to investigate the capillary patterns among the groups. Anti-CD31/PCAM1 immunohistochemistry was also used for further confirmation of changes in capillary parameters.

Results

The results demonstrated that capillaries were protected by MSC sheets in the flap tissue, and the thickness of the epidermal layer was improved, indicationg the possible beneficial effects of MSC sheets on diabetic wound treatment.

Conclusion

Stem cells, as ac-BMMSCs, may decrease the levels of wound healing complications in diabetes and can be considered as a cell therapy option in such conditions.

Copeptin, pro-atrial natriuretic peptide and pro-adrenomedullin as markers of hypoxic stress in patients with obstructive sleep apnea-a prospective intervention study

Study Objectives

Obstructive sleep apnea (OSA) might lead to oxidative stress, inflammation and elevated circulating copeptin, proANP and proADM levels. We aimed to evaluate whether the levels of these prohormones are higher in patients with OSA and whether they might change under continuous positive airway pressure (CPAP) therapy, serving as potential proxies for the diagnosis and therapy-response in OSA.

Methods

A total of 310 patients with suspicion of OSA were recruited. Screening for OSA was performed using overnight pulse oximetry followed by polygraphy and a venous puncture in the morning. All patients diagnosed with OSA underwent CPAP adaptation. A venous puncture was conducted in the night before CPAP and in the following morning. At 1 and 6 months of treatment, polygraphy was performed, followed by a venous puncture in the morning. In the acquired blood, copeptin, proANP and proADM levels were measured.

Results

We analyzed 232 patients with OSA and 30 patients without OSA. Our results indicated that only copeptin levels differed significantly among patients with and without OSA at baseline. In OSA patients, the levels of proADM significantly changed after 1 and 6 months on CPAP therapy, when compared to baseline (p < 0.001 and p = 0.020). Additionally, proANP levels significantly decreased after 12 h on CPAP therapy, as compared to baseline levels (p < 0.001).

Conclusions

Copeptin is significantly associated with the presence of OSA. ProANP levels might serve as a potential proxy for the acute response to non-invasive ventilation (12 h), while proADM reflects the long-term response (1 and 6 months).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01704-0.

Adrenomedullin: Continuing to explore cardioprotection

Adrenomedullin (AM), a peptide isolated from an extract of human pheochromocytoma, comprises 52 amino acids with an intramolecular disulfide bond and amidation at the carboxy-terminus. AM is present in various tissues and organs in rodents and humans, including the heart. The peptide concentration increases with cardiac hypertrophy, acute myocardial infarction, and overt heart failure in the plasma and the myocardium. The principal function of AM in the cardiovascular system is the regulation of the vascular tone by vasodilation and natriuresis via cyclic adenosine monophosphate-dependent or -independent mechanism. In addition, AM may possess unique properties that inhibit aldosterone secretion, oxidative stress, apoptosis, and stimulation of angiogenesis, resulting in the protection of the structure and function of the heart. The AM receptor comprises a complex between calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein (RAMP) 2 or 3, and the AM-CLR/RAMP2 system is essential for heart development during embryogenesis. Small-scale clinical trials have proven the efficacy and safety of recombinant AM peptide therapy for heart failure. Gene delivery and a modified AM peptide that prolongs the half-life of the native peptide could be an innovative method to improve the efficacy and benefit of AM in clinical settings. In this review, we focus on the pathophysiological roles of AM and its receptor system in the heart and describe the advances in AM and proAM-derived peptides as diagnostic biomarkers as well as the therapeutic application of AM and modified AM for cardioprotection.

Precursor proadrenomedullin influences cardiomyocyte survival and local inflammation related to myocardial infarction

Increased adrenomedullin (ADM) levels are associated with various cardiac diseases such as myocardial infarction (MI). ADM is cleaved off from the full-length precursor protein proadrenomedullin (ProADM) during its posttranslational processing. To date, no biological effect of ProADM is reported, while ADM infusion leads to antiapoptotic effects and improved cardiac function. Using an MI mouse model, we found an induction of ProADM gene as well as protein expression during the early phase of MI. This was accompanied by apoptosis and increasing inflammation, which substantially influence the post-MI remodeling processes. Simulating ischemia in vitro, we demonstrate that ProADM expression was increased in cardiomyocytes and cardiac fibroblasts. Subsequently, we treated ischemic cardiomyocytes with either ProADM or ADM and found that both proteins increased survival. This effect was diminishable by blocking the ADM₁ receptor. To investigate whether ProADM and ADM play a role in the regulation of cardiac inflammation, we analyzed chemokine expression after treatment of cells with both proteins. While ProADM induced an expression of proinflammatory cytokines, thus promoting inflammation, ADM reduced chemokine expression. On leukocytes, both proteins repressed chemokine expression, revealing antiinflammatory effects. However, ProADM but not ADM dampened concurrent activation of leukocytes. Our data show that the full-length precursor ProADM is biologically active by reducing apoptosis to a similar extent as ADM. We further assume that ProADM induces local inflammation in affected cardiac tissue but attenuates exaggerated inflammation, whereas ADM has low impact. Our data suggest that both proteins are beneficial during MI by influencing apoptosis and inflammation.

Calcitonin Peptide Family Members Are Differentially Regulated by LPS and Inhibit Functions of Rat Alveolar NR8383 Macrophages

Members of the calcitonin peptide family—calcitonin gene-related peptide (CGRP), adrenomedullin (AM), and adrenomedullin2/intermedin (IMD)–exert modulatory effects upon monocytes and macrophages of various extrapulmonary origins. Utilizing the rat alveolar macrophage (AMφ) cell line NR8383, we here set out to determine to which extent these three peptides and their receptors are differentially regulated in AMφ and what specific effects they have on AMφ key functions. LPS treatment differentially up-regulated expression of the peptides and receptors. Among the three peptides, IMD mRNA content was lowest both in primary rat AMφ and NR8383 cells, whereas IMD peptide dominated in basal and LPS-stimulated secretion from NR8383 cells. Fcγ receptor-mediated phagocytosis and TNF-α production were inhibited by AM, IMD, and CGRP, whereas pro-IL-1β mRNA was slightly down-regulated exclusively by CGRP. Neither of these peptides affected IL-6 or IL-10 production. None increased intracellular calcium concentration, but AM significantly inhibited store-operated calcium entry. In conclusion, the rat AMφ cell line NR8383 is both a source and a target of the calcitonin peptide family members AM, IMD, and CGRP. Despite sharing proteins of the receptor complexes, AM, IMD, and CGRP each showed a characteristic pattern of effects and regulation, suggesting that these closely related peptides are not just redundant members of one common signaling pathway but act in concert by addressing parallel signaling cascades. Since peptide and receptor expression are up-regulated by LPS, these signaling pathways might act as inhibitory feedback mechanisms in pulmonary bacterial infection.

Intermedin1-53 Protects Against Myocardial Fibrosis by Inhibiting Endoplasmic Reticulum Stress and Inflammation Induced by Homocysteine in Apolipoprotein E-Deficient Mice

AIM

Endoplasmic reticulum stress (ERS) and inflammation participate in cardiac fibrosis. Importantly, a novel paracrine/autocrine peptide intermedin_1-53 (IMD_1-53) in the heart inhibits myocardial fibrosis in rats. However, the mechanisms are yet to be fully elucidated.

METHODS

Myocardial fibrosis in apolipoprotein E-deficient (ApoE -/-) mice and neonatal rat cardiac fibroblasts (CFs) were induced using homocysteine (Hcy).

RESULTS

IMD_1-53 inhibited myocardial fibrosis in vivo and in vitro. Picrosirius red staining showed that IMD_1-53 reduced myocardial interstitial collagen deposition in ApoE-/- mice treated with Hcy and decreased the expression of myocardial collagen I and III, which was further verified in rat CFs. IMD_1-53 attenuated myocardial hypertrophy, as shown by cardiomyocyte cross-sectional area, ratio of heart weight to body weight, and mRNA levels of atrial natriuretic peptide and brain natriuretic peptide. IMD_1-53 inhibited the upregulation of ERS hallmarkers such as glucose-regulated protein 78 (GRP78), GRP94, activating transcription factor 6 (ATF6), ATF4, inositol-requiring enzyme 1α, spliced-X-box-binding protein-1, protein kinase receptor-like ER kinase, and eukaryotic translation initiation factor 2α in mouse myocardium and rat CFs treated with Hcy. In addition, IMD_1-53 decreased the production of inflammatory factors such as tumor necrosis factor-α, monocyte chemotactic protein-1, interleukin-6 (IL-6), and IL-1β in the mouse myocardium and rat CFs treated with Hcy. Concurrently, IMD_1-53 ameliorated the expression of nuclear factor-κB, transforming growth factor-β1, and c-Jun N-terminal kinase in the mouse myocardium and rat CFs treated with Hcy.

CONCLUSIONS

IMD potentially protects against myocardial fibrosis induced by Hcy in ApoE-/- mice, possibly via attenuating myocardial ERS and inflammation.

Adrenomedullin-RAMP2 system is crucially involved in retinal angiogenesis

Adrenomedullin (ADM) is an endogenous peptide first identified as a strong vasodilating molecule. We previously showed that in mice, homozygous knockout of ADM (ADM(-/-)) or its receptor regulating protein, RAMP2 (RAMP2(-/-)), is embryonically lethal due to abnormal vascular development, thereby demonstrating the importance of ADM and its receptor signaling to vascular development. ADM expression in the retina is strongly induced by ischemia; however, its role in retinal pathophysiology remains unknown. Here, we analyzed oxygen-induced retinopathy (OIR) using heterozygous ADM and RAMP2 knockout mice models (ADM(+/-) or RAMP2(+/-), respectively). In addition, we analyzed the role of the ADM-RAMP2 system during earlier stages of retinal angiogenesis using an inducible endothelial cell-specific RAMP2 knockout mouse line (DI-E-RAMP2(-/-)). Finally, we assessed the ability of antibody-induced ADM blockade to control pathological retinal angiogenesis in OIR. In OIR, neovascular tufts, avascular zones, and hypoxic areas were all smaller in ADM(+/-) retinas compared with wild-type mice. ADM(+/-) retinas also exhibited reduced levels of VEGF and eNOS expression. DI-E-RAMP2(-/-) showed abnormal retinal vascular patterns in the early stages of development. However, ADM enhanced the proliferation and migration of retinal endothelial cells. Finally, we found intravitreal injection of anti-ADM antibody reduced pathological retinal angiogenesis. In conclusion, the ADM-RAMP2 system is crucially involved in retinal angiogenesis. ADM and its receptor system are potential therapeutic targets for controlling pathological retinal angiogenesis.

Adrenomedullin in sinusoidal endothelial cells play protective roles against cold injury of liver

Donor organ damage caused by cold preservation is a major problem affecting liver transplantation. Cold preservation most easily damages liver sinusoidal endothelial cells (LSECs), and information about the molecules modulating LSECs function can provide the basis for new therapeutic strategies. Adrenomedullin (AM) is a peptide known to possess anti-apoptotic and anti-inflammatory properties. AM is abundant in vascular endothelial cells, but levels are comparatively low in liver, and little is known about its function there. In this study, we demonstrated both AM and its receptors are expressed in LSECs. AM treatment reduced LSECs loss and apoptosis under cold treatment. AM also downregulated cold-induced expression of TNFalpha, IL1beta, IL6, ICAM1 and VCAM1. AM reduced apoptosis and expression of ICAM1 and VCAM1 in an in vivo liver model subjected to cold storage. Conversely, apoptosis was exacerbated in livers from AM and RAMP2 (AM receptor activity-modifying protein) knockout mice. These results suggest that AM expressed in LSECs exerts a protective effect against cold-organ damage through modulation of apoptosis and inflammation.