Carboxypeptidase M (CPM) metabolizes several bioactive peptides by removing their C-terminal arginine residues. It was postulated that the substrates include the anaphylatoxins C3a and C5a generating their less active desArg forms. C3a and C5a are potent mediators of inflammation, shaping both innate and adaptive immune responses. Considering that CPM is a membrane-bound enzyme expressed in multiple organs, we hypothesized that it may protect tissues from anaphylatoxin-driven damage. Using mass spectrometry, we confirmed that CPM efficiently converts C3a and C5a into their desArg forms. We then generated CPM-deficient rats and subjected them to a complement-dependent model of acute lung injury. Compared to controls, CPM-deficient rats exhibited consistently exacerbated lung damage, including higher histological injury scores, increased neutrophil and macrophage infiltration, and elevated expression of inflammatory marker genes. These findings indicate that CPM protects the lung from complement-mediated injury and highlight it as a potential therapeutic target in inflammatory diseases.

Cerebral malaria (CM) from Plasmodium falciparum is a major cause of death in African children. Since bradykinin (BK) is a mediator of vasogenic edema, we hypothesized that it contributes to the pathogenesis of CM in Kenyan children and Plasmodium berghei ANKA-infected (PbA-infected) C57BL/6J mice in experimental CM (ECM). Cleaved plasma high-molecular-weight kininogen (cHK) is a marker for BK release. 40% of children with central nervous system malaria had plasma cHK versus 18% of children with uncomplicated malaria. Wild-type PbA-infected mice with ECM had circulating cHK, elevated BK levels, and reduced HK and prekallikrein activity/antigen levels. HK-null (Kng1-/-), combined BK B1- and B2 receptor-null (Bdkrb1-/-Bdkrb2-/-), BK B2 receptor-null (Bdkrb2-/-), or BK B1 receptor-null (Bdkrb1-/-) mice were protected significantly from neurologic deterioration and brain edema compared with wild-type mice. F12-/- mice were not protected from neurological deterioration. Prekallikrein-null (Klkb1-/-), prolylcarboxypeptidase hypomorph (Prcpgt/gt), and brain endothelial cell conditional KO of PRCP (Prcpfl/fl Cre) mice with ECM had reduced neurologic deterioration and brain edema. Adjuvant plasma kallikrein inhibition combined with artesunate treatment in PbA-infected mice reversed neurologic deterioration and brain edema and significantly prolonged survival over artesunate alone. BK-induced vasogenic edema contributes to human and murine CM.

Abstract Angiotensin-converting enzyme 2 (ACE2) functions as the receptor for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The virus utilizes the cellular endocytic machinery for entry by binding to defined residues on ACE2 with its spike protein (S protein), whose activation requires a priming process by another transmembrane protease, the transmembrane protease serine 2 (TMPRSS2). In addition, ACE2 itself is cleaved by TMPRSS2, which has been shown to be critical for viral pathology. This study aimed to elucidate the relationship between ACE2 and TMPRSS2 and the mechanism of ACE2 processing under normal cellular conditions. It is shown that interaction of ACE2 with TMPRSS2 results in altered processing, modification and cellular localization. Glycosylation of ACE2 has a major impact on TMPRSS2 interaction, trafficking and shedding of the enzyme. Studies in newly generated TMPRSS2-knockout rats reveal increased ACE2 levels in tissues supporting an important role of TMPRSS2 in ACE2 shedding also in vivo.

Chronic stress, frequently associated with dysfunction of the hypothalamic–pituitary–adrenal (HPA) axis and reduced neuroplasticity, is a major risk factor for psychiatric disorders such as anxiety and depression. The present study aimed to validate a 21-day chronic unpredictable stress (CUS) model and to investigate the effects of the Mas receptor agonist AVE0991 on stress-induced behavioral and molecular alterations. Male C57BL/6J mice were exposed to a 21-day CUS protocol. Animals were randomly assigned to four groups: control + saline, CUS + saline, control + AVE0991, and CUS + AVE0991 (3 mg/kg, i.p.). AVE was administered daily during the last two weeks of the stress protocol. Behavioral tests were performed to evaluate anxiety- and depressive-like behaviors, and plasma corticosterone, blood glucose levels, and brain-derived neurotrophic factor (BDNF) levels in the prefrontal cortex, hippocampus, and hypothalamus were measured. CUS exposure significantly increased plasma corticosterone and glucose levels and induced anxiety- and depressive-like behaviors. Stressed animals also showed reduced BDNF levels in the prefrontal cortex, hippocampus, and hypothalamus. Treatment with AVE0991 attenuated the increase in corticosterone and prevented stress-induced hyperglycemia. Moreover, AVE0991 reduced depressive-like behavior, increased latency to immobility, and improved anxiety-related parameters in the elevated plus maze and open field tests without affecting locomotor activity. AVE0991 also prevented the reduction of BDNF levels in stress-exposed animals. These findings validate the CUS model and demonstrate that activation of the Mas receptor by AVE0991 exerts anxiolytic, antidepressant, and neuroprotective effects, supporting its potential as a therapeutic strategy for stress-related neuropsychiatric disorders.

The kallikrein-kinin system (KKS) has been extensively studied in peripheral tissues, but its role in the central nervous system (CNS) remains poorly understood. The bradykinin B2 receptor (B2R) is constitutively expressed in the brain, where it may modulate neuronal differentiation, neuroplasticity, and behavioral aspects. Here, we investigated the functional role of striatal B2R by conditionally deleting the Bdkrb2 gene in the dorsal striatum of adult male mice (Bdkrb2flox/flox) using bilateral stereotaxic injections of an AAV8 that induces Cre and tdTomato expression. Mice lacking B2R in the dorsal striatum displayed several context-dependent behavioral alterations, such as reduced anxiety-like behavior and decreased sucrose preference. Moreover, these animals showed enhanced voluntary wheel running, suggesting alterations in motivation-related behavioral output. Immunofluorescence analysis revealed that among dTomato-positive neurons, approximately 17% co-expressed DARPP-32, indicating that a subset of the transduced cells corresponds to dopaminoceptive medium spiny neurons. Together, these findings show that dorsal striatal B2R deletion alters anxiety-related and motivational/hedonic behaviors in male mice and suggest that these effects may involve striatal neuronal populations, including a subset of dopaminoceptive neurons.

Stress is defined as a disruption of homeostasis that elicits adaptive responses aimed at restoring physiological balance. However, when stress becomes chronic or overwhelming, maladaptive changes may occur, contributing to endocrine, behavioral, and neuropsychiatric dysfunctions. Beyond the classical neuroendocrine axes, such as the sympatho-adrenomedullary and hypothalamic–pituitary–adrenal (HPA) axes, the renin-angiotensin system has also being implicated in stress modulation. Previous studies have shown that angiotensin-(1–7), acting through its receptor Mas, exerts a modulatory effect on the stress response, attenuating anxiety- and depression-like behaviors induced by various stressors. Here we investigated the impact of genetic deletion of Mas on the consequences of chronic unpredictable stress (CUS) exposure. Over 21 consecutive days, mice were subjected to random stressors, after which endocrine, behavioral and neurochemical assessments were performed. Mas knockout (KO) mice exposed to CUS exhibited significantly elevated corticosterone and blood glucose levels compared to stressed wild-type mice. In behavioral tests, stressed Mas KO mice displayed the highest immobility times in the forced swimming test, indicating enhanced depressive-like behavior. Anxiety-like behavior was also heightened in Mas KO mice, as evidenced by a significant reduction in the percentage of time spent in the open arms of the elevated plus maze test. Neurochemical analysis revealed a marked reduction in brain-derived neurotrophic factor (BDNF) levels in key brain regions of stressed Mas KO animals. Together, these findings suggest that Mas plays a critical role in the neurobiology of stress, since its absence exacerbates HPA axis hyperactivity, depression- and anxiety-like behaviors, as well as BDNF reduction. Overall, these results highlight the potential neuroprotective role of Mas in stress-related disorders.

The X allele of ACTN3 R577X polymorphism results in α-actinin-3 deficiency and has been associated with muscle damage and impaired recovery. While its role has been explored in musculoskeletal and cardiac contexts, no studies have evaluated its impact on chronic kidney disease (CKD). To investigate the prevalence of the ACTN3 R577X polymorphism in patients with end-stage renal disease undergoing hemodialysis (HD) and explore its potential involvement in renal fibrosis through experimental models. A total of 217 HD patients and 413 healthy controls were genotyped for the ACTN3 R577X polymorphism. Associations with clinical variables were analyzed using multivariate regression. Renal Actn3 expression was evaluated in mice subjected to folic acid-induced acute and chronic kidney injury. In vitro, fibroblasts were exposed to TGF-β or LPS to assess gene expression responses. The X allele was significantly more frequent in HD patients (83.7% vs. 64.4%, p < 0.0001), and XX individuals began HD up to 11 years earlier than RR homozygotes. Experimental models showed persistent upregulation of Actn3 in fibrotic kidneys and in TGF-β-treated fibroblasts, but not in inflammatory conditions. Actn3 expression paralleled that of fibrosis markers such as Col1a1 and Acta2. The ACTN3 X allele is associated with earlier onset of renal failure and increased susceptibility to tubulointerstitial disease. Experimental data support its involvement in renal fibrosis. ACTN3 genotyping may help identify patients at greater risk for CKD progression.

Cerebral malaria (CM) due to Plasmodium falciparum ( Pf ) infection is a major cause of death in African children. Bradykinin (BK) is a mediator of vasogenic edema. It could contribute to the pathogenesis of central nervous system malaria in Kenyan children and P. berghei ANKA ( PbA ) infected C57BL/6J mice with experimental cerebral malaria. Cleaved plasma high molecular weight kininogen (cHK) is a marker for prior BK release. 40% of children with central nervous system malaria had plasma cHK versus 18% of children with uncomplicated malaria. Wild-type PbA -infected mice had circulating plasma cHK, elevated BK levels, and reduced HK and prekallikrein levels. HK null ( Kng1 -/- ), combined BK B1 and B2 receptor null ( Bdkrb1 -/- / Bdkrb2 -/- ), BK B2 ( Bdkrb2 -/- ) or BK B1 ( Bdkrb1 -/- ) receptor null mice were protected from neurologic deterioration and brain edema compared to wild-type mice. F12 -/- mice were not protected from neurological deterioration. Prekallikrein null ( Klkb1 -/- ), prolylcarboxypeptidase hypomorphs ( Prcp gt/gt ), and brain endothelial cell conditional knockout of PRCP ( Prcp fl/fl Cre) mice had reduced neurologic deterioration and brain edema. Adjuvant plasma kallikrein inhibition combined with artesunate treatment of PbA -infected mice reversed neurologic deterioration and brain edema and prolonged survival relative to artesunate alone. BK-induced vasogenic edema contributes to human and murine CM.

ATP6AP2 (ATPase H⁺ Transporting Accessory Protein 2) also known as (pro)renin receptor (P)PR is expressed in the central nervous system (CNS). In humans, variants of ATP6AP2 have been linked to neurodegenerative disorders and mental retardation and to changes in the volume of the hippocampus—a limbic brain structure that is capable of adult hippocampal neurogenesis. Cell proliferation in the adult dentate gyrus (DG) can be positively modulated by voluntary exercise. Somewhat surprisingly, we have recently shown that ATP6AP2 overexpression does not show any significant effects on the number of newly generated cells in the DG in transgene-heterozygous mice. Therefore, we now analyzed the effects of voluntary exercise on cell proliferation in the adult hippocampus in female mice overexpressing ATP6AP2 on both alleles. ATP6AP2 mRNA levels in forebrain and hippocampus were increased dose-dependently compared with wild-type mice, with homozygous exhibiting stronger effects than heterozygous mice. Full-length ATP6AP2 protein levels were also increased dose-dependently in forebrain, but the protein fragment representing the soluble prorenin receptor was not. In total hippocampus extracts, no significant differences in ATP6AP2 protein levels were found. However, in the DG, ATP6AP2 immunoreactivity was markedly increased. While the running pattern of mice with access to a running wheel was similar between the groups, cell proliferation, as indicated by BrdU staining, was increased in wild-type mice as expected, but failed to increase in homozygous ATP6AP2 mice. This finding indicates that ATP6AP2 overexpression does not affect basal adult cell proliferation per se but inhibits plastic changes in the rate of cell proliferation. Thus, ATP6AP2 appears to selectively limit exercise-dependent regulation in the hippocampus rather than baseline neurogenic capacity.

The classical renin-angiotensin-aldosterone system (RAAS) remains one of the most important pharmacological targets in the treatment of cardiorenovascular diseases, including hypertension, heart failure, and chronic kidney disease. Pharmacological modulation of the RAAS has transformed clinical practice over the past decades. The earliest agents targeting this pathway were mineralocorticoid receptor antagonists, which were followed by ACE (angiotensin-converting enzyme) inhibitors, Ang (angiotensin) AT1R (AT1 receptor) blockers, and direct renin inhibitors. These drug classes continue to represent the cornerstone of guideline-directed therapy, and newer compounds within these categories are being developed to enhance efficacy, improve organ protection, and minimize adverse effects such as hyperkalemia, hypotension, and renal dysfunction. In addition to established therapies, innovative strategies targeting the classical RAAS are emerging. These include RNA-based therapeutics designed to suppress hepatic angiotensinogen synthesis and small-molecule inhibitors of aldosterone synthase. Such approaches may offer improved cardiovascular and renal outcomes by intervening earlier, more sustainably, or selectively in the RAAS cascade. Beyond the classical axis, increasing attention is being directed toward the so-called protective or alternative renin-angiotensin system (RAS). This pathway centers on ACE2, Ang-(1-7), alamandine, and their associated receptors, including Mas, MrgD (Mas-related G-protein-coupled receptor D), and the Ang AT2R (AT2 receptor). Activation of this axis exerts vasodilatory, anti-inflammatory, antifibrotic, and cardioprotective effects, thereby counterbalancing the deleterious actions of the classical RAAS. Growing experimental and clinical evidence supports its therapeutic potential not only in cardiovascular disease but also in metabolic, fibrotic, and inflammatory disorders. This review summarizes the current state of pharmacological interventions targeting both the classical and protective RAAS and highlights emerging therapeutic directions that may shape the next generation of cardiovascular treatments.

This study explores the anatomical distribution of Angiotensin-(Ang)-(1-7) fusion protein within the central nervous system of the novel transgenic rat model (TG7371). The Ang-(1-7)/Mas pathway of the renin-angiotensin system (RAS) plays a key role in cardiovascular regulation and influences higher brain functions, including cognition and emotion. TG7371 expresses a transgenic Ang-(1-7)-producing fusion protein which resulted in a hypotensive phenotype. Here, we assessed the expression of Ang-(1-7) fusion mRNA and protein in primary cortical cells from neonates and identified their distribution in the brain of adult rats using qPCR, WB, ISH, and immunolabeling. In neonates, Ang-(1-7) mRNA was mainly found in proliferating cells, whereas in adults, it was primarily identified in GFAP-positive astrocytes. The Ang-(1-7) fusion protein, however, was predominantly found in neurons, including GABAergic interneurons and specific pyramidal cells. High protein levels were particularly noted in cardiovascular control regions like the medulla, as well as in other non-cardiovascular areas. TG7371 displayed twofold increase in brain levels of Ang-(1-7) compared to Ang II vs. Control, which remained unchanged, alongside significant changes in the expression of RAS components and nNOS. These findings indicate that the Ang-(1-7) fusion protein modulates the GABA-nNOS-NO-pathway, contributing to the low blood pressure phenotype of these rats, and promotes a mode of astrocytes-neurons-communication. The widespread expression of the fusion protein in the brain also suggests a potential role in modulating mood, cognition, and neurological disorders. Overall, TG7371 presents a valuable model to explore the long-term cardiovascular and neurobehavioral effects of Ang-(1-7), highlighting promising therapeutic implications and neural crosstalk.

The kallikrein-kinin system (KKS) plays a key role in inflammatory responses, but its specific contribution to neuroinflammation remains to be fully elucidated. The bradykinin B2 receptor (B2R), a principal effector of the KKS, is widely expressed in both neuronal and glial cells in the rodent and human brain. In this study, we investigated the molecular contribution of B2R to neuroinflammation using complementary in vitro and in vivo models. Lipopolysaccharide (LPS) stimulation significantly upregulated B2R mRNA expression in primary astrocyte cultures and in the cortical tissue of wild-type mice. Pharmacological blockade of B2R in astrocytes markedly suppressed the LPS-induced proinflammatory gene expression. In contrast, B2R antagonism in vivo resulted in only partial attenuation of the neuroinflammatory response. Together, these findings suggest cell type-specific roles for B2R and underscore its key contribution to astrocyte-mediated neuroinflammation.

Angiotensin-converting enzymes (ACE and ACE2) are key components of the renin-angiotensin-aldosterone system (RAAS) and are present in the gastrointestinal tract and intestinal content, preserving their catalytic activity, and may interact with the gut microbiota. The present study aimed to determine the origin of fecal ACE and ACE2 activity. Fecal pellets from germ-free, ACE and ACE2 knockout (KO) mice, and from the corresponding controls were analyzed using fluorimetric enzyme activity assays. ACE activity was assessed using Hippuryl-His-Leu and Z-Phe-His-Leu as substrates; ACE2 activity was assessed using Mca-APK (Dnp), with and without the ACE2 inhibitor MLN-4760. Germ-free mice showed increased fecal ACE and ACE2 activity compared to controls. ACE2-KO mice lacked fecal ACE2 activity, whereas ACE activity was unaffected. In ACE-KO mice, fecal ACE activity was reduced, but not abolished, while ACE2 activity remained similar to controls. In ACE C- and N-domain KO mice, ACE activity was similar to controls, and inhibition with captopril completely abolished fecal ACE activity using Hippuryl-His-Leu, but not Z-Phe-His-Leu, in those animals. These findings indicate that fecal ACE and ACE2 activity results from combined intestinal shedding and microbiota-related mechanisms, supporting a modulatory role of the gut environment on luminal RAAS activity.

Serotonin (5-HT) regulates neurodevelopment and behavior. Whereas central 5-HT is synthesized by tryptophan hydroxylase (TPH)-2, the TPH1 isoform produces 5-HT peripherally. Although these systems are anatomically segregated, TPH1 gene polymorphisms have been linked to neuropsychiatric vulnerability, suggesting that peripheral 5-HT may influence behavior through indirect pathways, potentially involving the gut-immune-brain axis. Here, we examined how lifelong peripheral 5-HT deficiency shapes behavior and cross-system communication in a sex-specific manner using adult TPH1 knockout (TPH1-/-) rats. Animals underwent behavioral testing combined with neurochemical and gene expression profiling, gut microbiome sequencing, and peripheral leukocyte phenotyping. TPH1-/- males and females displayed reduced anxiety-like behavior and enhanced attentional performance. TPH1-/- males also showed improved sociability and cognitive flexibility. These behavioral alterations were accompanied by attenuation of monoaminergic and GABA/glutamatergic signaling, alongside changes in HPA-axis and neuroplasticity-related pathways across cortico-limbic regions. Peripheral 5-HT deficiency further reshaped gut microbiome ecology, selectively reducing α-diversity in males and altering microbial community composition in both sexes. In the colon, TPH1 deficiency downregulated pro-inflammatory cytokines while upregulating adhesion marker expression. Circulating leukocyte populations were also altered, with reductions in γδ T cells, CD127+ CD8+ T cells, and B cells, and an increase in eosinophils. Integrative analyses showed that individual differences in anxiety-like behavior and cognition were associated with variation spanning neurochemical, microbial, and immune domains. Together, these findings support a role for peripheral 5-HT in behavioral regulation and reveal cross-system associations consistent with sex-specific modulation along the gut-immune-brain axis, while identifying TPH1-dependent signaling as a potential contributor to neuropsychiatric disorders’ pathophysiology.

Serotonin (5-HT) is critical for neurodevelopment, influencing brain maturation, emotional regulation, and social behavior. Tryptophan hydroxylase 2 (TPH2), the rate-limiting enzyme for central 5-HT synthesis, causes lifelong 5-HT depletion when disrupted. While early-life 5-HT perturbations are linked to neuropsychiatric vulnerability, it remains unclear how lifelong depletion shapes behavioral trajectories across development, or how sex and postnatal environment influence these effects. Here, we provide a longitudinal characterization of Tph2-deficient male and female rats, assessing reflex development, sensorimotor coordination, anxiety-like behavior, recognition memory, social interaction, and aggression across the first two months of life. To investigate environmental and microbial modulators, we quantified maternal care (e.g., licking/grooming, nursing, nest proximity) through daily observations during the first postnatal week and profiled adult gut microbiota via 16S rRNA sequencing. The association between maternal care and behavioral outcomes was assessed to identify environmental modulators of the Tph2 phenotype, while principal component analysis (PCA) visualized genotype- and sex-specific microbial clustering. Tph2−/− rats exhibited delayed sensorimotor maturation, altered emotional regulation, reduced object-directed exploration and sociability, and increased aggression, particularly in males. Sensorimotor and exploratory outcomes were positively associated with maternal care, reinforcing its role in shaping behavioral trajectories. Microbiota analysis revealed genotype- and sex-dependent alterations, with Tph2+/− males showing the most pronounced shifts, including increased microbial richness and taxonomic divergence. Together, our findings demonstrate that 5-HT depletion disrupts behavioral neurodevelopmental trajectories via interactions between genetic, environmental, and ecological factors, highlighting the importance of accounting for sex, environment, and developmental timing in translational research.

AIMS:To evaluate the molecular mechanisms involved in intermittent fasting 16/8 (16/8 IF), a widespread dietary practice adopted worldwide that consists of 16 h of fasting and 8 h of feeding. METHODS:Obese mice were fasted daily from 6 am to 10 pm. Food intake, body weight, and energy expenditure were measured. Molecular mechanisms were investigated using ELISA, western blot, and qPCR of white and brown adipose tissues. Glucose homeostasis was also evaluated. Ucp1 knockout and ob/ob mice were utilized. RESULTS:The 16/8 IF regimen improved glucose homeostasis and reduced body weight, food intake, and overall adiposity. Postprandial VO2, heat production, brown adipose tissue (BAT) temperature, and ketone bodies increased with 16/8 IF. Postprandial thermogenesis induced by 16/8 IF was abolished in mice after BAT denervation or Ucp1 deletion. Serum leptin levels were elevated, and most metabolic effects of 16/8 IF were absent in leptin-deficient ob/ob mice. Additionally, leptin sensitivity increased in mice exposed to 16/8 IF. CONCLUSION:The 16/8 IF regimen can improve metabolism, with findings underscoring the role of enhanced leptin action in inhibiting food intake and promoting postprandial thermogenesis during 16/8 IF.

Nucleocytoplasmic transport is crucial for neuronal cell physiology and defects are involved in neurodegenerative diseases like amyotrophic lateral sclerosis and Alzheimer’s disease, but also in ageing. Recent studies have suggested, that the classic nuclear import factor adapters KPNA3 (also named importin alpha4) and KPNA4 (also named importin alpha3) could be associated with the development of motor neuron diseases, a condition specifically affecting the neurons projecting from brain to spinal cord or from spinal cord to the muscles. Here we set out to analyze the neuronal function of mice deficient in KPNA3 (Kpna3-KO) or KPNA4 (Kpna4-KO). The motoric abilities and locomotion at different time points in ageing were tested to study the role of these two genes on motor neuron function. While we did not find deficits related to motor neurons in both mouse models, we discovered a hypermotoric phenotype in KPNA4-deficient mice. Attention deficit/hyperactivity disorder (ADHD) is caused by a combination of genetic, environmental and neurobiological factors and a number of genes have been suggested in genome-wide association studies to contribute to ADHD, including KPNA4. Here we provide supportive evidence for KPNA4 as a candidate pathogenic factor in ADHD, by analysing Kpna4-KO mice which show ADHD-like symptoms.

Blockade of AT1-receptors by telmisartan (TEL) has anti-atherosclerotic efficacy. We investigated to what extent the ACE2/Ang1-7/Mas axis-dependent mechanism contributes to the TEL-induced protection of endothelial function. Atherosclerosis was induced in C57BL/6 N, Mas-knock out (ko), and Ace2-ko mice by AAV-PCSK9DY (2 ×1011 VG) injections plus Western diet (WD) feeding (12w). Mice were treated (12w) with TEL or vehicle. Controls received no PCSK9DY, chow-feeding, and vehicle-treatment. In the aortae of mice, the plaque burden was determined, RNAseq analyses were performed and functional properties were assessed by quantifying the mechanical properties of the endothelial surface by Atomic Force Microscopy. Regardless of strain, plaque burden and total cholesterol were increased upon AAV-PCSK9DY+WD but decreased by TEL. Cortical stiffness was also enhanced in all strains by AAV-PCSK9DY+WD but reduced under TEL only in the C57BL/6 N, while remaining still high in both knockout strains. Plasma NO negatively correlated with cortical stiffness in C57BL/6 N, but not in transgenic mice. TNFα plasma levels and aortic MMP12 expression was increased in PCSK9DY/WD vehicle-treated controls and was normalized by TEL in C57BL/6 N but not in Mas-ko and Ace2-ko mice. We conclude that TEL-induced reduction of endothelial stiffness occurred only in the C57BL/6 N but not in the Mas-ko and Ace2-ko mice. We suggest that the protective TEL effect is partly due to an Ang(1-7)/ACE2/Mas axis mediated mechanism. Since Mmp12 has well-known proatherogenic properties but was not altered in the two transgenic mouse lines, follow-up studies are required to further elucidate the correlation between Mmp12 and the Ang(1-7)/ACE2/Mas axis with respect to atherosclerosis.