LP2, the first lanthipeptide GPCR agonist in a human pharmacokinetics and safety study

Introduction of a lanthionine into a peptide may enhance target affinity, target specificity and proteolytic resistance. This manuscript reports preclinical safety studies and the first-in-human study with the lanthipeptide AT 2R agonist LP2, a structural analog of cAng-(1–7), whose N-terminus was protected against aminopeptidases by the presence of a D-lysine. None of the preclinical studies, including an in vitro multitarget panel, behavioral, respiratory and cardiovascular measurements, genotoxicity and toxicity studies in rat and dog, posed any safety concern. Due to lack of toxicity the maximum tolerated dose was not reached neither in rat nor in dog. In the human dose escalation study, healthy male volunteers received a single 1 mL subcutaneous injection (0.001 mg, 0.01 mg or 0.1 mg) of LP2 or matching placebo. In contrast to angiotensin II which has a T 1/2 in plasma of < 1 min, LP2 has a T 1/2 of approximately 2.1–2.6 hours. The fraction of the dose excreted unchanged in urine ranged from 84.73 ± 10.4 % at a dose of 0.001 mg to 66.4 ± 3.9 % at 0.1 mg. There were no deaths, serious adverse events or subject withdrawals as a result of an adverse event. The incidence of adverse events was 16.7 %; each was mild in severity. One adverse event, peripheral coldness, was considered to be possibly related to LP2 at 0.001 mg LP2. None of the results was considered to pose a clinically relevant safety concern. This study supports the potential for the therapeutic use of lanthipeptides

AT2 receptor agonist LP2 restores respiratory function in a rat model of bleomycin-induced lung remodelling

This study aimed to evaluate the prophylactic and therapeutic potential of angiotensin II type 2 receptor peptide agonist LP2 in bleomycin-induced airway and cardiac remodeling in rats. Male Wistar rats were intratracheally instillated with bleomycin. Animals of a prophylactic arm received LP2 from day 0 at intraperitoneal doses of 1, 3 or 10μg/kg/d, whereas animals from a therapeutic arm received this LP2 treatment from day 7. On day 28 direct lung mechanics were determined and cardiac and lung tissues were collected and (histo)morphologically assessed. Prophylactic LP2 at 1µg/kg/d with bleomycin, versus bleomycin alone, significantly improved the airway pressure responses at fixed inflation of 4ml (p&lt;0.05) and 7ml volume (p&lt;0.05), static compliance (p&lt;0.01), inspiratory capacity (p&lt;0.05), lung tolerance of increased volume (p&lt;0.0001), right to left ventricular hypertrophy (p&lt;0.05). Therapeutic regime showed a similar trend as the prophylactic arm but was less effective, mostly lacking significance. However, and importantly, therapeutic LP2 at 1µg/kg/d significantly decreased mRNA expression of collagen 1A1 (p&lt;0.01), of Connective Tissue Growth Factor 1 (p&lt;0.05) and of Tissue MetalloPeptidase inhibitor 1 (p&lt;0.05). In conclusion, a very low dose of 1µg/kg/d LP2 has capacity to counter bleomycin-induced impairment of lung functioning and consequent cardiac remodeling.</p

Biosynthesis of lanthionine-constrained agonists of G protein-coupled receptors

The conformation with which natural agonistic peptides interact with G protein-coupled receptor(s) (GPCR(s)) partly results from intramolecular interactions such as hydrogen bridges or is induced by ligand-receptor interactions. The conformational freedom of a peptide can be constrained by intramolecular cross-links. Conformational constraints enhance the receptor specificity, may lead to biased activity and confer proteolytic resistance to peptidic GPCR agonists. Chemical synthesis allows to introduce a variety of cross-links into a peptide and is suitable for bulk production of relatively simple lead peptides. Lanthionines are thioether bridged alanines of which the two alanines can be introduced at different distances in chosen positions in a peptide. Thioether bridges are much more stable than disulfide bridges. Biosynthesis of lanthionine-constrained peptides exploiting engineered Gram-positive or Gram-negative bacteria that contain lanthionine-introducing enzymes constitutes a convenient method for discovery of lanthionine-stabilized GPCR agonists. The presence of an N-terminal leader peptide enables dehydratases to dehydrate serines and threonines in the peptide of interest after which a cyclase can couple the formed dehydroamino acids to cysteines forming (methyl)lanthionines. The leader peptide also guides the export of the formed lanthionine-containing precursor peptide out of Gram-positive bacteria via a lanthipeptide transporter. An engineered cleavage site in the C-terminus of the leader peptide allows to cleave off the leader peptide yielding the modified peptide of interest. Lanthipeptide GPCR agonists are an emerging class of therapeutics of which a few examples have demonstrated high efficacy in animal models of a variety of diseases. One lanthipeptide GPCR agonist has successfully passed clinical Phase Ia.</p

Prevention and Intervention Studies with Telmisartan, Ramipril and Their Combination in Different Rat Stroke Models

The effects of AT1 receptor blocker, telmisartan, and the ACE inhibitor, ramipril, were tested head-to head and in combination on stroke prevention in hypertensive rats and on potential neuroprotection in acute cerebral ischemia in normotensive rats. Normotensive Wistar rats were treated s.c. 5 days prior to middle cerebral artery occlusion (MCAO) for 90 min with reperfusion. Groups (n = 10 each): (1) sham, (2) vehicle (V; 0,9% NaCl), (3) T (0,5 mg/kg once daily), (4) R (0,01 mg/kg twice daily), (5) R (0,1 mg/kg twice daily) or (6) T (0,5 mg/kg once daily) plus R (0,01 mg/kg twice daily). Twenty-four and 48 h after MCAO, neurological outcome (NO) was determined. Forty-eight h after MCAO, infarct volume by MRI, neuronal survival, inflammation factors and neurotrophin receptor (TrkB) were analysed.Stroke incidence was reduced, survival was prolonged and neurological outcome was improved in all treated SHR-SP with no differences between treated groups. In the acute intervention study, T and T+R, but not R alone, improved NO, reduced infarct volume, inflammation (TNFα), and induced TrkB receptor and neuronal survival in comparison to V.T, R or T+R had similar beneficial effects on stroke incidence and NO in hypertensive rats, confirming BP reduction as determinant factor in stroke prevention. In contrast, T and T+R provided superior neuroprotection in comparison to R alone in normotensive rats with induced cerebral ischemia

Pharmakologische Stimulation des AT2-Rezeptors aktiviert endogene neuroprotektive und neuroregenerative Mechanismen über BDNF-mediierte Signalwege

The renin-angiotensin system (RAS) plays an important role in the initiation and progression of cardiovascular diseases. The detrimental actions of the AT1 receptor (AT1R) including cardiac and vascular hypertrophy, inflammation and apoptosis have been well established and described. Recently, several publications have suggested novel, protective actions of the RAS not only in the cardiovascular- but also in the nervous system. The so-called protective arm of the RAS includes AT2- and Mas receptors and is characterized by effects different from and often opposing those of the AT1R. In the current work, the neuro-protective and neuro-regenerative potential of AT2R stimulation was studied in detail. In an animal model of stroke, indirect stimulation of AT2R reduced stroke volume and promoted neuronal survival accompanied by improved sensomotoric functions. In animals subjected to spinal cord injury, AT2R stimulation ameliorated locomotor performance in a time-dependent manner suggesting involvement of neuro-regenerative processes. An extensive analysis of the tissue samples revealed elevated numbers of regenerating axons cranially and caudally from the lesion area in animals treated with an AT2R agonist. The underlying mechanisms were elucidated using gene expression analysis and morphological assays. The results showed for the first time that the neuro-protective and neuro-regenerative actions of AT2R are mediated through a defined neurotrophic pathway.Entstehung und Progression kardiovaskulärer Erkrankungen werden maßgeblich durch das Renin-Angiotensin-System (RAS) beeinflusst. Viele der pathologischen Effekte des AT1-Rezeptors (AT1R), darunter Herz- und Gefäßhypertrophie, Inflammation und Zelltod, sind mittlerweile weitgehend untersucht. In mehreren kürzlich erschienenen Publikationen wurde jedoch beschrieben, dass dem RAS auch eine protektive Seite zukommt und dies nicht nur auf kardiovaskulärer Ebene, sondern auch im Nervensystem. Zum "protektiven Arm" des RAS zählen der AT2- und der MAS-Rezeptor, welche unterschiedliche, dem AT1R teilweise diametral entgegengesetzte Effekte vermitteln. In der vorliegenden Arbeit wurden die neuroprotektiven und neuroregenerativen Effekte einer direkten AT2R-Stimulation detailliert untersucht. Im Schlaganfall-Tiermodell konnte gezeigt werden, dass die indirekte Stimulation des AT2R zu einer Reduktion des Infarktareals führt und neuronalen Zelluntergang inhibiert, wobei sich dies auch in einer verbesserten sensomotorischen Leistung der Versuchstiere bemerkbar machte. Bei Versuchstieren mit Rückenmarksverletzung zeigte eine direkte AT2R-Stimulation in zeitabhängiger Weise einen positiven Einfluss auf deren Lokomotor-Funktion, was auf zu Grunde liegende neuroregenerative Prozesse schließen ließ. In ausführlichen Analysen von Gewebeproben konnte demonstriert werden, dass die mit einem AT2R-Agonisten behandelte Tiere in cranial und caudal der Läsion gelegenen Regionen eine vermehrte Anzahl an regenerierenden Axonen aufweisen. Zur Darstellung des zugrundeliegenden Mechanismus kamen Expressionsanalysen und morphologische Assays zum Einsatz. Die Ergebnisse zeigen zum ersten Mal, dass die neuroprotektiven und neuroregenerativen Effekte des AT2R durch definierte neurotrophe Signalwege vermittelt werden

Aldosterone synthase inhibitors in cardiovascular and renal diseases

Aldosterone is involved in various cardiovascular pathologies, including hypertension, heart failure, atherosclerosis and fibrosis. Mineralocorticoid receptor (MR)-dependent and -independent, genomic and non-genomic processes mediate its complex effects. Spironolactone and eplerenone, both MR antagonists, are the only commercially available compounds targeting directly the actions of aldosterone. However, due to the poor selectivity (spironolactone), low potency (eplerenone) and the fact that only MR-dependent effects of aldosterone can be inhibited, these drugs have limited clinical use. An attractive approach to abolish potentially all of aldosterone-mediated pathologies is the inhibition of aldosterone synthase. This review summarizes current knowledge on the complex effects mediated by aldosterone, potential advantages and disadvantages of aldosterone inhibition and novel directions in the development of aldosterone synthase inhibitors

Does activation of the protective Renin-Angiotensin System have therapeutic potential in COVID-19?

Infection of lung cells by the corona virus results in a loss of the balance between, on the one hand, angiotensin II-mediated stimulation of the angiotensin II type 1 receptor and, on the other hand, stimulation of the angiotensin II type 2 receptor and/or the Mas receptor. The unbalanced enhanced stimulation of the angiotensin II type 1 receptor causes inflammation, edema and contributes to the pathogenesis of severe acute respiratory distress syndrome. Here we hypothesize that stable, receptor-specific agonists of the angiotensin II type 2 receptor and of the Mas receptor are molecular medicines to treat COVID-19 patients. These agonists have therapeutic potential in the acute disease but in addition may reduce COVID-19-associated long-term pulmonary dysfunction and overall end-organ damage of this disease