Transforming growth factor betas are upregulated in the rat masseter muscle hypertrophied by clenbuterol, a beta2 adrenergic agonist

Efficacy of Irbesartan in Celiprolol-Treated Patients With Vascular Ehlers-Danlos Syndrome

BACKGROUND

Vascular Ehlers-Danlos syndrome is a rare genetic disorder characterized by defective type III collagen and a high risk of arterial morbidity and mortality. Several cardiovascular drugs are used for treatment, including celiprolol, but no controlled trial in this condition has been conducted to date. We hypothesized the benefit of the addition of an angiotensin II receptor blocker.

METHODS

A multicenter, randomized, placebo-controlled trial was conducted to assess the efficacy and safety of the angiotensin II receptor blocker irbesartan in adults with vascular Ehlers-Danlos syndrome on stable background celiprolol therapy. Patients were randomized 1:1 to receive irbesartan (150 mg/day titrated to 300 mg/day) or placebo for 2 years. The composite primary outcome was defined as any vascular Ehlers-Danlos syndrome-related fatal or nonfatal arterial event or any new or worsening arterial lesions detected by systematic head-to-pelvis computed tomography angiography or peripheral arterial duplex ultrasound at different time points, using a time-to-first-event analysis.

RESULTS

Twenty-nine participants (62% female; 40.3±11.3 years of age) were randomized to irbesartan, and 28 (64% female; 40.7±11.0 years of age) were randomized to placebo. The composite primary outcome occurred in 8 of 29 patients (27.6%) receiving irbesartan versus 15 of 28 patients (53.6%) receiving placebo (hazard ratio, 0.42 [95% CI, 0.17, 0.99]; P<0.05). The risk of recurrent symptomatic or nonsymptomatic arterial events was lower with irbesartan than with placebo (risk ratio, 0.37 [95% CI, 0.19, 0.68]; P=0.002). A reduction of progression of arterial lesions was observed at all sites. Irbesartan significantly reduced systolic blood pressure compared with placebo (baseline-adjusted difference of 5.4 mm Hg [P<0.001]), but no relation was observed with the reduction of the primary composite outcome. Eleven episodes of irbesartan-related hypotension were recorded, leading to a downtitration in 4 patients.

CONCLUSIONS

Compared with placebo, irbesartan reduced the risk of severe symptomatic and asymptomatic arterial events in patients with vascular Ehlers-Danlos syndrome on background celiprolol therapy.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02597361.

Current Evidence and Future Perspectives in the Medical Management of Vascular Ehlers-Danlos Syndrome: Focus on Vascular Prevention

Vascular Ehlers-Danlos syndrome (vEDS) is a rare autosomal dominant connective tissue disease resulting from pathogenic variants in the collagen type III alpha 1 chain (COL3A1) gene, encoding type III procollagen. Patients with vEDS present with severe tissue fragility that can result in arterial aneurysm, dissection, or rupture, especially of medium-caliber vessels. Although early reports have indicated a very high mortality rate in affected patients, with an estimated median survival of around 50 years, recent times have seen a remarkable improvement in outcomes in this population. This shift could be related to greater awareness of the disease among patients and physicians, with improved management both in terms of follow-up and treatment of complications. Increasing use of drugs acting on the cardiovascular system may also have contributed to this improvement. In particular, celiprolol, a β1 cardio-selective blocker with a β2-agonist vasodilator effect, has been shown to reduce rates of vascular events in patients with vEDS. However, the evidence on the true benefits and possible mechanisms responsible for the protective effect of celiprolol in this specific setting remains limited. Drugs targeting the extracellular matrix organization and autophagy-lysosome pathways are currently under investigation and could play a role in the future. This narrative review aims to summarize current evidence and future perspectives on vEDS medical treatment, with a specific focus on vascular prevention.

Despite celiprolol therapy, patients with vascular Ehlers-Danlos syndrome remain at risk of vascular events: A 12-year experience in an Italian referral center

BACKGROUND

Vascular Ehlers-Danlos syndrome (vEDS) is an inherited connective tissue disorder characterized by arterial fragility. Celiprolol has been suggested to significantly reduce rates of vascular events in this setting, though real-world evidence is limited. The aim of this study was to report our experience with celiprolol therapy in vEDS management.

METHODS

Patients with a genetically confirmed diagnosis of vEDS who were referred for outpatient consultation at the Brescia University Hospital between January 2011 and July 2023 were included. At each visit, patients' medical history, results of vascular imaging, and office blood pressure measurements were recorded. Celiprolol therapy was progressively titrated to the maximum tolerated dose of up to 400 mg daily, according to the patients' tolerance.

RESULTS

Overall, 26 patients were included. Female sex was prevalent (62%). Mean (SD) age was 37 (16) years. Follow-up duration was 72 (41) months. At the last follow-up visit, all patients were on celiprolol therapy, 80% of whom were taking the maximum recommended dose. The yearly risk of symptomatic vascular events was 8.8%, the majority of which occurred after reaching the maximum recommended dose of celiprolol. No significant predictor of symptomatic vascular events was identified among patients' clinical characteristics.

CONCLUSION

In our cohort, rates of celiprolol use were high and the drug was well tolerated overall. Nonetheless, the risk of symptomatic vascular events remained nonnegligible. Future studies should identify reliable predictors of major adverse events and explore additional therapeutic strategies that could further lower the risk of life-threatening events in this population.

Different effects of medications for hypertension on renal function between patients with and without diabetes mellitus undergoing percutaneous coronary intervention: a retrospective single-center cohort study

BACKGROUND

Diabetes mellitus (DM) and hypertension are well-known atherosclerosis risk factors. Furthermore, renal dysfunction is a crucial risk factor for patients with coronary artery disease (CAD), and managing renal function in these patients is complicated because of comorbid conditions and potential side effects during treatment. Therefore, this study aimed to investigate the effect of medications for hypertension on renal function after percutaneous coronary intervention (PCI) between patients with and without DM with statins.

METHODS

In 297 consecutive patients undergoing PCI for stable angina pectoris, cystatin C (CysC) was evaluated at baseline and 9 months after PCI, and the percent change in CysC (%CysC) was calculated. The association of worsening renal function (WRF: %CysC ≥ 0) and baseline characteristics, including medications, was assessed.

RESULTS

Among 297 hypertensive patients with statins, 196 and 101 were with and without DM, respectively. Angiotensin-converting enzyme inhibitor (ACEI), angiotensin II receptor blocker, and β-blocker were prescribed in 56 (29%), 82 (42%), and 91 (46%) patients in the DM group, and 20 (20%), 52 (51%), and 52 (51%) in the non-DM group, respectively. The patients with WRF after PCI were 100 (51%) and 59 (58%) in the DM and non-DM groups (p = 0.261). Additionally, the %CysC had no significant differences between groups [median: 0%, interquartile range (IQR): -7.9% to 8.5% vs. median: 1.1%, IQR: -6.6% to 9.6%, p = 0.521]. Multivariate logistic analysis for WRF using relevant factors from univariate analysis showed that only β-blocker [odds ratio (OR): 2.76, 95% confidence interval (CI): 1.03-7.90, p = 0.048] was independently associated with WRF in the DM group whereas ACEI (OR: 0.07, 95% CI: 0.01-0.47, p = 0.012) was negatively correlated with WRF in the non-DM group.

CONCLUSION

The β-blocker was the independent risk factor for WRF in patients with DM in the late phase after PCI for stable angina pectoris, while the use of ACEI had a renoprotective effect in patients without DM.

Microcirculation and Macrocirculation in Hypertension: A Dangerous Cross-Link?

Microcirculation and macrocirculation are tightly interconnected into a dangerous cross-link in hypertension. Small artery damage includes functional (vasoconstriction, impaired vasodilatation) and structural abnormalities (mostly inward eutrophic remodeling). These abnormalities are major determinants of the increase in total peripheral resistance and mean blood pressure (BP) in primary hypertension, which in the long term induces large artery stiffening. In turn, large artery stiffening increases central systolic and pulse pressures, which are further augmented by wave reflection in response to the structural alterations in small resistance arteries. Finally, transmission of high BP and flow pulsatility to small resistance arteries further induces functional and structural abnormalities, thus leading to increased total peripheral resistance and mean BP, thus perpetuating the vicious circle. Hyperpulsatility, in addition to higher mean BP, exaggerates cardiac, brain, and kidney damages and leads to cardiovascular, cerebral, and renal complications. The dangerous cross-link between micro and macrocirculation can be reversed into a virtuous one by ACE (angiotensin-converting enzyme) inhibitors, sartans, and calcium channel blockers. These three pharmacological classes are more potent than β-blockers and diuretics for reducing arterial stiffness and small artery remodeling. The same ranking was observed for their effectiveness at reducing left ventricular hypertrophy, preserving glomerular filtration rate, and preventing dementia, suggesting that they can act beyond brachial BP reduction, by breaking the micro/macrocirculation vicious circle.

Celiprolol Treatment in Patients with Vascular Ehlers-Danlos Syndrome

OBJECTIVE

Vascular Ehlers-Danlos syndrome (vEDS) is a rare monogenetic disease caused by pathogenic variants in procollagen 3A1. Arterial rupture is the most serious clinical manifestation. A randomised controlled trial, the Beta-Blockers in Ehlers-Danlos Syndrome Treatment (BBEST) trial, reported a significant protective effect of the beta blocker celiprolol. The aim was to study the outcome of celiprolol treatment in a cohort of Swedish patients with vEDS.

METHODS

Uppsala is a national referral centre for patients with vEDS. They are assessed by vascular surgeons, angiologists, and clinical geneticists. Family history, previous and future clinical events, medication, and side effects are registered. Celiprolol was administered twice daily and titrated up to a maximum dose of 400 mg daily. Logistic regression was used to analyse predictors of vascular events.

RESULTS

Forty patients with pathogenic sequence variants in COL3A1 were offered treatment with celiprolol in the period 2011-2019. The median follow up was 22 months (range 1-98 months); total follow up was 106 patient years. In two patients, uptitration of the dose is ongoing. Of the remaining 38, 26 (65%) patients reached the target dose of 400 mg daily. Dose uptitration was unsuccessful in six patients because of side effects; one died before reaching the maximum dose, and five terminated the treatment. Five major vascular events occurred; four were fatal (ruptured ascending aorta; aortic rupture after type B dissection; ruptured cerebral aneurysm; and ruptured pulmonary artery). One bled from a branch of the internal iliac artery, which was successfully coiled endovascularly. The annual risk of a major vascular event was 4.7% (n = 5/106), similar to the treatment arm of the BBEST trial (5%) and lower than in the control arm of the same trial (12%). No significant predictor of vascular events was identified.

CONCLUSION

Treatment with celiprolol is tolerated in most patients with vEDS. Despite fatal vascular events, these observations suggest that celiprolol may have a protective effect in vEDS.

Vascular Smooth Muscle Cells and Arterial Stiffening: Relevance in Development, Aging, and Disease

The cushioning function of large arteries encompasses distension during systole and recoil during diastole which transforms pulsatile flow into a steady flow in the microcirculation. Arterial stiffness, the inverse of distensibility, has been implicated in various etiologies of chronic common and monogenic cardiovascular diseases and is a major cause of morbidity and mortality globally. The first components that contribute to arterial stiffening are extracellular matrix (ECM) proteins that support the mechanical load, while the second important components are vascular smooth muscle cells (VSMCs), which not only regulate actomyosin interactions for contraction but mediate also mechanotransduction in cell-ECM homeostasis. Eventually, VSMC plasticity and signaling in both conductance and resistance arteries are highly relevant to the physiology of normal and early vascular aging. This review summarizes current concepts of central pressure and tensile pulsatile circumferential stress as key mechanical determinants of arterial wall remodeling, cell-ECM interactions depending mainly on the architecture of cytoskeletal proteins and focal adhesion, the large/small arteries cross-talk that gives rise to target organ damage, and inflammatory pathways leading to calcification or atherosclerosis. We further speculate on the contribution of cellular stiffness along the arterial tree to vascular wall stiffness. In addition, this review provides the latest advances in the identification of gene variants affecting arterial stiffening. Now that important hemodynamic and molecular mechanisms of arterial stiffness have been elucidated, and the complex interplay between ECM, cells, and sensors identified, further research should study their potential to halt or to reverse the development of arterial stiffness.

Effect of celiprolol on prevention of cardiovascular events in vascular Ehlers-Danlos syndrome: a prospective randomised, open, blinded-endpoints trial

BACKGROUND

Vascular Ehlers-Danlos syndrome is a rare severe disease that causes arterial dissections and ruptures that can lead to early death. No preventive treatment has yet been validated. Our aim was to assess the ability of celiprolol, a β(1)-adrenoceptor antagonist with a β(2)-adrenoceptor agonist action, to prevent arterial dissections and ruptures in vascular Ehlers-Danlos syndrome.

METHODS

Our study was a multicentre, randomised, open trial with blinded assessment of clinical events in eight centres in France and one in Belgium. Patients with clinical vascular Ehlers-Danlos syndrome were randomly assigned to 5 years of treatment with celiprolol or to no treatment. Randomisation was done from a centralised, previously established list of sealed envelopes with stratification by patients' age (≤32 years or >32 years). 33 patients were positive for mutation of collagen 3A1 (COL3A1). Celiprolol was administered twice daily and uptritrated by 100 mg steps every 6 months to a maximum of 400 mg per day. [DOSAGE ERROR CORRECTED]. The primary endpoints were arterial events (rupture or dissection, fatal or not). This study is registered with ClinicalTrials.gov, number NCT00190411.

FINDINGS

53 patients were randomly assigned to celiprolol (25 patients) or control groups (28). Mean duration of follow-up was 47 (SD 5) months, with the trial stopped early for treatment benefit. The primary endpoints were reached by five (20%) in the celiprolol group and by 14 (50%) controls (hazard ratio [HR] 0·36; 95% CI 0·15-0·88; p=0·040). Adverse events were severe fatigue in one patient after starting 100 mg celiprolol and mild fatigue in two patients related to dose uptitration.

INTERPRETATION

We suggest that celiprolol might be the treatment of choice for physicians aiming to prevent major complications in patients with vascular Ehlers-Danlos syndrome. Whether patients with similar clinical presentations and no mutation are also protected remains to be established.

FUNDING

French Ministry of Health, Programme Hospitalier de Recherche Clinique 2001.

Adaptive effects of the beta2-agonist clenbuterol on expression of beta2-adrenoceptor mRNA in rat fast-twitch fiber-rich muscles

Administration of the beta(2)-agonist clenbuterol has been shown to reduce the expression of beta(2)-adrenoceptor (AR) mRNA in fast-twitch fiber-rich (extensor digitorum longus, EDL) muscle without changing that in slow-twitch fiber-rich (soleus, SOL) muscle in rats. However, the regulatory mechanism for muscle fiber type-dependent down-regulation of the expression of beta(2)-AR mRNA induced by clenbuterol is still unclear. Therefore, mRNA expression of transcriptional and post-transcriptional regulatory factors for beta(2)-AR mRNA levels in fast-twitch fiber-rich (EDL and plantaris, PLA) and slow-twitch fiber-rich (SOL) muscles in clenbuterol-administered (1.0 mg/kg body weight/day for 10 days, subcutaneous) rats was studied by real-time reverse transcription-polymerase chain reaction. Administration of clenbuterol significantly reduced expression of beta(2)-AR mRNA in EDL and PLA muscles without changing that in SOL muscle. Administration of clenbuterol also significantly reduced the mRNA expression of transcriptional regulatory factor (glucocorticoid receptor) and mRNA stabilizing factor (Hu antigen R) in EDL and PLA muscles without changing those in SOL muscle. These results suggest that muscle fiber type-dependent effects of clenbuterol on expression of beta(2)-AR mRNA are closely related to the down-regulation of mRNA expression of transcriptional and post-transcriptional regulatory factors for beta(2)-AR mRNA levels.

The role of beta-adrenoceptor signaling in skeletal muscle: therapeutic implications for muscle wasting disorders

PURPOSE OF REVIEW

The beta-adrenergic signaling pathway represents a novel therapeutic target for skeletal muscle wasting disorders due to its roles in regulating protein synthesis and degradation. beta-Adrenoceptor agonists (beta-agonists) have therapeutic potential for attenuating muscle wasting associated with sarcopenia (age-related muscle wasting), cancer cachexia, sepsis, disuse, burns, HIV-AIDS, chronic kidney or heart failure, and neuromuscular diseases such as the muscular dystrophies. This review describes the role of beta-adrenergic signaling in the mechanisms controlling muscle wasting due to its effects on protein synthesis, protein degradation, and muscle fiber phenotype.

RECENT FINDINGS

Stimulation of the beta-adrenergic signaling pathway with beta-agonists has therapeutic potential for muscle wasting since administration can elicit an anabolic response in skeletal muscle. As a consequence of their potent muscle anabolic actions, the effects of beta-agonist administration have been examined in several animal models and human conditions of muscle wasting in the hope of discovering a new therapeutic. The repartitioning characteristics of beta-agonists (increasing muscle mass and decreasing fat mass) have also made them attractive anabolic agents for use in livestock and by some athletes. However, potentially deleterious cardiovascular side-effects of beta-agonists have been identified and these will need to be obviated in order for the therapeutic potential of beta-agonists to be realized.

SUMMARY

Multiple studies have identified anticachectic effects of beta-agonists and their therapeutic potential for pathologic states when muscle protein hypercatabolism is indicated. Future studies examining beta-agonist administration for muscle wasting conditions need to separate beneficial effects on skeletal muscle from potentially deleterious effects on the heart and cardiovascular system.

The effect of a low dose of clenbuterol on rat soleus muscle submitted to joint immobilization

The aim of the present study was to evaluate the effect of joint immobilization on morphometric parameters and glycogen content of soleus muscle treated with clenbuterol. Male Wistar (3-4 months old) rats were divided into 4 groups (N = 6 for each group): control, clenbuterol, immobilized, and immobilized treated with clenbuterol. Immobilization was performed with acrylic resin orthoses and 10 microg/kg body weight clenbuterol was administered subcutaneously for 7 days. The following parameters were measured the next day on soleus muscle: weight, glycogen content, cross-sectional area, and connective tissue content. The clenbuterol group showed an increase in glycogen (81.6%, 0.38 +/- 0.09 vs 0.69 +/- 0.06 mg/100 g; P < 0.05) without alteration in weight, cross-sectional area or connective tissue compared with the control group. The immobilized group showed a reduction in muscle weight (34.2%, 123.5 +/- 5.3 vs 81.3 +/- 4.6 mg; P < 0.05), glycogen content (31.6%, 0.38 +/- 0.09 vs 0.26 +/- 0.05 mg/100 mg; P < 0.05) and cross-sectional area (44.1%, 2574.9 +/- 560.2 vs 1438.1 +/- 352.2 microm(2); P < 0.05) and an increase in connective tissue (216.5%, 8.82 +/- 3.55 vs 27.92 +/- 5.36%; P < 0.05). However, the immobilized + clenbuterol group showed an increase in weight (15.9%; 81.3 +/- 4.6 vs 94.2 +/- 4.3 mg; P < 0.05), glycogen content (92.3%, 0.26 +/- 0.05 vs 0.50 +/- 0.17 mg/100 mg; P < 0.05), and cross-sectional area (19.9%, 1438.1 +/- 352.2 vs 1724.8 +/- 365.5 microm(2); P < 0.05) and a reduction in connective tissue (52.2%, 27.92 +/- 5.36 vs 13.34 +/- 6.86%; P < 0.05). Statistical analysis was performed using Kolmogorov-Smirnov and homoscedasticity tests. For the muscle weight and muscle glycogen content, two-way ANOVA and the Tukey test were used. For the cross-sectional area and connective tissue content, Kruskal-Wallis and Tukey tests were used. This study emphasizes the importance of anabolic pharmacological protection during immobilization to minimize skeletal muscle alterations resulting from disuse.

Effects of clenbuterol, a β₂-adrenergic agonist, on sizes of masseter, temporalis, digastric, and tongue muscles

We compared the hypertrophic effects of clenbuterol, a β₂-adrenergic agonist, on the masseter, digastric, and temporalis with those on the tongue, tibialis anterior, soleus, diaphragm, and heart. The weights of masseter, digastric and temporalis in the clenbuterol group were 36 ~ 56% greater than those in the control group, whereas those of the tibialis anterior, diaphragm, and heart weights in the clenbuterol group were 9 ~ 33% greater than those in the control group. No significant difference in the weights of the soleus and tongue was found between the control and clenbuterol groups. Taken together with our present and previously reported results, it is suggested that the hypertrophic effects of clenbuterol on the masseter, digastric, and temporalis are greater than those on the limb, trunk, and heart.

TGF-β1and TNF-α are involved in the transcription of type I collagen α2gene in soleus muscle atrophied by mechanical unloading

The aim of this study was to examine the effect of hindlimb suspension (HS) on the expressions of COL1A2 (type I collagen α2chain) mRNA and its regulatory factors, transforming growth factors (TGF)-β1, -β2, and -β3, phosphorylated Smad3, and tumor necrosis factor-α (TNF-α) in rat hindlimb muscles. Forty-eight male Wistar rats (age, 5 wk) were randomly assigned to HS for 1, 3, 7, and 14 days and control ( n = 6 for each). During the exposure to HS, COL1A2 mRNA expression decreased in the soleus muscle at day 3 and recovered to control level at day 7. The content of TNF-α, one of the negative regulatory factors for COL1A2, increased from day 3 until day 14. On the other hand, the contents of TGF-β1, TGF-β3, and Smad3, positive regulatory factors for COL1A2, increased at day 7. The in situ hybridization for COL1A2 and the immunohistochemistry of TGF-β1and TNF-α revealed their expressions around nerve-related tissues, including muscle spindles and connective tissue sheath. The results indicate that the transcriptional activity of COL1A2 in the soleus muscle initially decreases in response to unloading through an increase in TNF-α production; thereafter, it returns toward normal level through the activated TGF-β/Smad pathway.

Role of Transforming Growth Factor β in Rat Bladder Smooth Muscle Cell Proliferation

Conditions associated with hypertrophy of the urinary bladder have repeatedly been associated with an increased urinary excretion of transforming growth factor (TGF) beta in both rats and patients. Because TGFbeta can have both growth-promoting and -inhibiting effects, we have studied its effects on cell growth and death in primary cultures of rat bladder smooth muscle cells. TGFbeta1, TGFbeta2, or TGFbeta3 did not cause apoptosis, but all three isoforms inhibited DNA synthesis with similar potency (EC(50) of approximately 0.1 ng/ml) and efficacy. Such inhibition was antagonized by a specific TGFbeta receptor antagonist and independent of the presence of serum. Mitogen-activated protein kinases (MAPKs) are involved in the control of cell growth, and all three TGFbeta isoforms inhibited activation of the extracellular signal-regulated kinase, c-Jun NH(2)-terminal kinase, and p38 MAPK subfamilies. Nevertheless, the inhibitory effects of the TGFbeta isoforms on DNA synthesis were not affected by presence of inhibitors of the three MAPK pathways. TGFbeta did not alter cell size as measured by flow cytometry or mitochondrial activity, an integrated measure of cell size and number. We conclude that our data do not support the hypothesis that TGFbeta is a mediator of rat bladder hypertrophy.