SS-31

Mitochondrial Calcium Dysregulation and Targeted Therapies in Heart Failure.

Mengting Liu, Yunpeng Jin

Heart failure (HF) is steadily increasing in prevalence and poses a major global health challenge, with substantial medical and economic burdens. HF represents the terminal stage of diverse cardiac disorders and is characterized by poor prognosis despite the availability of conventional pharmacological treatments, underscoring the urgent need for novel therapeutic approaches. Accumulating evidence highlights a strong association between HF and mitochondrial dysfunction, of which dysregulated mitochondrial calcium (mCa2+) homeostasis plays a pivotal role in disease pathogenesis. Ca2+ serves as an essential signaling messenger that regulates energy metabolism and also governs cell survival and myocardial contractility. Thus, this review introduces the mechanisms of mCa2+ uptake and efflux and the association of these processes with HF and emerging therapeutic strategies. We also discuss mCa2+ uniporter (MCU) inhibitors and Elamipretide, a mitochondria-targeted peptide. Collectively, this work provides novel insights and preclinical evidence supporting mitochondria-based interventions for HF.

Early targets and progressive deterioration in cardiac performance in response to chronically modified cardiac troponin I.

Vani S Ravichandran, Tabea M Schatz, Emily Lavey +9 more

Protein kinase C (PKC) targeted thin filament cardiac troponin I (cTnI) Ser43/45 phosphorylation (p-S43/45) increases during heart failure (HF). Chronic cTnI p-S43/45 causes contractile dysfunction in cardiac myocytes, but the in vivo impact is less clear. To investigate the in vivo impact of this cluster, three lines of transgenic mice were generated with high (HE-), moderate (ME-), and low (LE-) phosphomimetic cTnIS43/45D (SD) replacement of endogenous cTnI within sarcomere thin filament. Each mouse line developed chronic in vivo and/or cellular contractile dysfunction, which initiated structural remodeling and a progressive deterioration in cardiac function. Higher cTnISD replacement levels accelerated the rate of deterioration and progression to end-stage heart failure. In further work, cTnISD initiated sarcomere communication to produce early alterations in mitochondria before the progressive deterioration in cardiac performance. Specifically, early reductions developed in mitochondrial/nuclear DNA, mitochondrial master regulator gene expression, electron transport proteins, and antioxidants along with increased mitochondria-related oxidative stress before extensive remodeling in cTnISD mice. In addition, cTnISD mice developed early differences in mitochondrial ultrastructure and evidence favoring fusion over fission compared with nontransgenic (Ntg) littermates. A second-generation peptide derived from elamipretide improved survival and slowed the progression of remodeling and contractile dysfunction. Overall, the results demonstrate that chronic cTnISD causes cardiac dysfunction and initiates early mitochondrial responses that serve as important drivers of progressive deterioration in cardiac performance to end-stage HF.NEW & NOTEWORTHY Elevated cardiac troponin I (cTnI) Ser43/45 phosphorylation accompanies human heart failure. A mouse model with phosphomimetic substitutions shows that chronic sarcomere replacement with cTnI Ser43/45Asp causes cardiac dysfunction and initiates early downstream changes in mitochondria before the onset of progressive remodeling and progressive deterioration in cardiac performance. These early alterations include differences in mitochondrial architecture and function and oxidative stress. Early mitochondrial targeting improves survival and cardiac function.

Therapeutic Approaches Involving Mitochondria in the Treatment of Acute Kidney Injury.

Prisha S Patel, Navjot S Pabla, Amandeep Bajwa

Acute kidney injury (AKI) continues to pose a significant clinical burden, characterized by high morbidity and mortality rates. Emerging evidence has established mitochondrial dysfunction as a central driver in the pathogenesis of AKI, encompassing deficits in bioenergetics, excessive production of reactive oxygen species, and disruption of mitochondrial dynamics. Therapeutic interventions targeting mitochondrial pathways-most notably peptide-based agents such as SS-31-have demonstrated promising results in preclinical models. Recent discoveries have identified phospholipid scramblase 3 (PLSCR3) as an essential mediator of SS-31's mitochondrial protective effects, positioning it as a novel therapeutic target. This review synthesizes current mitochondrial-directed approaches for AKI, with a particular emphasis on the mechanistic role of PLSCR3 in maintaining mitochondrial homeostasis and injury responses. Despite encouraging data, mitochondrial therapies face several translational hurdles, including limited bioavailability, challenges in establishing effective dosing regimens, incomplete mechanistic understanding, and variability in efficacy across different experimental models. Moreover, concerns regarding cost, accessibility, and long-term safety remain unresolved, contributing to inconsistent outcomes in clinical trials. Herein we evaluate the emerging role of PLSCR3 as a potentially druggable mitochondrial target, supported by recent genetic, biochemical, and in vivo evidence, and discuss translational strategies that may bridge the gap between experimental promise and clinical application.

Mitochondrial Targeting by Elamipretide Improves Myocardial Bioenergetics Without Translating into Functional Benefits in HFpEF.

Antje Schauer, Daniela Jahn, Beatrice Vahle +6 more

Mitochondrial dysfunction contributes to impaired myocardial energetics and performance in heart failure with preserved ejection fraction (HFpEF). Elamipretide (Ela) enhances mitochondrial bioenergetics in preclinical models, yet its relevance in HFpEF remains unclear. This study examined the effects of Ela on cardiac mitochondrial function, structure, and cardiovascular performance in a rodent HFpEF model. Female obese ZSF1 rats received vehicle or Ela for 12 weeks, with age-matched lean rats as controls. Cardiac function and hemodynamics were assessed by echocardiography and pressure-volume analysis. Mitochondrial respiration was measured in permeabilized fibers and ultrastructure evaluated by transmission electron microscopy. Molecular and histological analyses included cardiolipin lipidomics and mRNA/protein profiling of hypertrophic, fibrotic, and inflammatory markers. Ela modestly improved complex I and II respiration, whereas mitochondrial ultrastructure, cardiolipin composition, and tafazzin expression were unchanged. Diastolic dysfunction persisted, reflected by unchanged E/é, ventricular stiffness factor β, and titin phosphorylation. Compared to untreated HFpEF, systolic performance showed a mild decline, with small reductions in LV ejection fraction and end-systolic elastance. Accordingly, cardiac remodeling, including hypertrophy, fibrosis, and inflammatory activation, remained unaltered. Vascular stiffness slightly increased, while carotid reactivity and morphology were preserved. In conclusion, despite enhanced mitochondrial respiration following Ela treatment, no functional or structural benefits were observed in experimental HFpEF, suggesting limited therapeutic efficacy once HFpEF is established.

Real-world disease burden and health care resource utilization for patients with Barth syndrome.

Lindsay Marjoram, Yonglin Huang, Mary Kay Koenig +2 more

Barth syndrome (BTHS) is an ultra-rare, X-linked genetic disorder for which there is limited economic data. Because compiling such data that target rare indications is difficult, we assessed real-world data to increase understanding of the cost of BTHS based on disease burden and health care resource utilization (HCRU).

Reviving the Mitochondria: A Hopeful Horizon in Refractory Heart Failure.

Zeeshan Ahmed, Fnu Abdul Rehman, Syed Faqeer Hussain Bokhari

Refractory heart failure (HF) remains a pressing clinical challenge despite substantial progress in pharmacologic and device-based interventions. While current therapies target neurohormonal, hemodynamic, and metabolic derangements, a crucial element of cellular dysfunction often remains overlooked: mitochondrial health. Mitochondrial dysfunction plays a central role in the pathogenesis and progression of HF, contributing to bioenergetic failure, oxidative stress, and cardiomyocyte death. Recent advances in mitochondrial-targeted therapies have opened new possibilities for treating HF at its energetic roots. This editorial explores the pathophysiological role of mitochondria in HF, reviews emerging therapeutic strategies aimed at restoring mitochondrial function, and outlines key challenges that must be addressed to translate these innovations into clinical practice.

Elamipretide in the Management of Barth Syndrome: Current Evidence and a Case Report.

Neil Jacob, Daniel Schecter, Molly Marshall +5 more

Barth syndrome is an exceedingly rare and potentially fatal X-linked mitochondrial disease arising from pathogenic variants in TAFAZZIN (TAZ), leading to defects in mature cardiolipin synthesis and its integration into the mitochondrial inner mitochondrial membrane. Clinical features that may be severe include cardiomyopathy, cyclic neutropenia, skeletal myopathy, and growth delay. Currently, no FDA-approved therapies exist. Elamipretide (ELAM) has been shown to stabilize cardiolipin and improve mitochondrial bioenergetics in pre-clinical and clinical studies in older individuals with Barth syndrome. Here we describe a case of prenatally identified Barth syndrome-related severe left ventricle (LV) non-compaction cardiomyopathy, where ELAM was initiated shortly after birth for clinical heart failure and was associated with significant and sustained clinical improvement leading to an inactive status on the heart transplant list with eventual anticipated delisting. We provide a review of the current literature including the pathophysiology of Barth syndrome, the mechanism of action of ELAM, and its clinical applications.

Cardiac pathology in a patient with a novel pathogenic variant c.703del (p.Ile235SerfsTer4) of the TAFAZZIN gene.

Marisa Prasanpanich, Majid Husain, Nancy J Halnon +4 more

Barth syndrome is a mitochondrial disease caused by loss-of-function mutations in the TAFAZZIN gene located on chromosome Xq28 encoding a transacylase essential for cardiolipin remodeling. Most patients develop dilated cardiomyopathy and progressive heart failure within the first year of life with some requiring cardiac transplantation.

The mitochondrial-targeted peptide therapeutic elamipretide improves cardiac and skeletal muscle function during aging without detectable changes in tissue epigenetic or transcriptomic age.

Wayne Mitchell, Gavin Pharaoh, Alexander Tyshkovskiy +3 more

Aging-related decreases in cardiac and skeletal muscle function are strongly associated with various comorbidities. Elamipretide (ELAM), a novel mitochondrial-targeted peptide, has demonstrated broad therapeutic efficacy in ameliorating disease conditions associated with mitochondrial dysfunction across both clinical and pre-clinical models. ELAM is proposed to restore mitochondrial bioenergetic function by stabilizing inner membrane structure and increasing oxidative phosphorylation coupling and efficiency. Although ELAM treatment effectively attenuates physiological declines in multiple tissues in rodent aging models, it remains unclear whether these functional improvements correlate with favorable changes in molecular biomarkers of aging. Herein, we investigated the impact of 8-week ELAM treatment on pre- and post- measures of C57BL/6J mice frailty, skeletal muscle, and cardiac muscle function, coupled with post-treatment assessments of biological age and affected molecular pathways. We found that health status, as measured by frailty index, cardiac strain, diastolic function, and skeletal muscle force are significantly diminished with age, with skeletal muscle force changing in a sex-dependent manner. Conversely, ELAM mitigated frailty accumulation and was able to partially reverse these declines, as evidenced by treatment-induced increases in cardiac strain and muscle fatigue resistance. Despite these improvements, we did not detect statistically significant changes in gene expression or DNA methylation profiles indicative of molecular reorganization or reduced biological age in most ELAM-treated groups. However, pathway analyses revealed that ELAM treatment showed pro-longevity shifts in gene expression such as upregulation of genes involved in fatty acid metabolism, mitochondrial translation and oxidative phosphorylation, and downregulation of inflammation. Together, these results indicate that ELAM treatment is effective at mitigating signs of sarcopenia and heart failure in an aging mouse model, but that these functional improvements occur independently of detectable changes in epigenetic and transcriptomic age. Thus, some age-related changes in function may be uncoupled from changes in molecular biological age.

Contemporary insights into elamipretide's mitochondrial mechanism of action and therapeutic effects.

Hani N Sabbah, Nathan N Alder, Genevieve C Sparagna +6 more

Mitochondria are cellular hubs integral for metabolism, signaling, and survival. Mitochondrial dysfunction is centrally involved in the aging process and an expansive array of disease states. Elamipretide is a novel mitochondria-targeting peptide that is under investigation for treating several disorders related to mitochondrial dysfunction. This review summarizes recent data that expand our understanding of the mechanism of action (MOA) of elamipretide. Elamipretide is a potential first-in-class therapeutic that targets the inner mitochondrial membrane. Despite initial descriptions of elamipretide's MOA involving reactive oxygen species scavenging, the last ten years have provided a significant expansion of how this peptide influences mitochondrial bioenergetics. The cardiolipin binding properties of elamipretide have been corroborated by different investigative teams with new findings about the consequences of elamipretide-cardiolipin interactions. In particular, new studies have shown elamipretide-mediated modulation of mitochondrial membrane electrostatic potentials and assembly of cardiolipin-dependent proteins that are centrally involved in mitochondrial physiology. These effects contribute to elamipretide's ability to improve mitochondrial function, structure, and bioenergetics. In animal studies, elamipretide-mediated amelioration of organ dysfunction has been observed in models of cardiac and skeletal muscle myopathies as well as ocular pathologies. A number of clinical trials with elamipretide have been recently completed, and a summary of the results focusing on Barth syndrome, primary mitochondrial myopathy, and age-related macular degeneration, is also provided herein. Elamipretide continues to show promise as a potential therapy for mitochondrial disorders. New basic science advances have improved understanding of elamipretide's MOA, enabling a better understanding of the molecular consequences of elamipretide-cardiolipin interactions.

Elamipretide: A Review of Its Structure, Mechanism of Action, and Therapeutic Potential.

Cheryl Tung, Fahimeh Varzideh, Emanuele Farroni +4 more

Mitochondria serve an essential metabolic and energetic role in cellular activity, and their dysfunction has been implicated in a wide range of disorders, including cardiovascular conditions, neurodegenerative disorders, and metabolic syndromes. Mitochondria-targeted therapies, such as Elamipretide (SS-31, MTP-131, Bendavia), have consequently emerged as a topic of scientific and clinical interest. Elamipretide has a unique structure allowing for uptake in a variety of cell types and highly selective mitochondrial targeting. This mitochondria-targeting tetrapeptide selectively binds cardiolipin (CL), a lipid found in the inner mitochondrial membrane, thus stabilizing mitochondrial cristae structure, reducing oxidative stress, and enhancing adenosine triphosphate (ATP) production. Preclinical studies have demonstrated the protective and restorative efficacy of Elamipretide in models of heart failure, neurodegeneration, ischemia-reperfusion injury, metabolic syndromes, and muscle atrophy and weakness. Clinical trials such as PROGRESS-HF, TAZPOWER, MMPOWER-3, and ReCLAIM elaborate on preclinical findings and highlight the significant therapeutic potential of Elamipretide. Further research may expand its application to other diseases involving mitochondrial dysfunction as well as investigate long-term efficacy and safety of the drug. The following review synthesizes current knowledge of the structure, mechanisms of action, and the promising therapeutic role of Elamipretide in stabilizing mitochondrial fitness, improving mitochondrial bioenergetics, and minimizing oxidative stress.

Cadmium-cardiolipin disruption of respirasome assembly and redox balance through mitochondrial membrane rigidification.

Nadiya Romanova, Kevin Sule, Travis Issler +5 more

The environmental pollutant cadmium (Cd) poses a threat to human health through the consumption of contaminated foodstuffs culminating in chronic nephrotoxicity. Mitochondrial dysfunction and excessive reactive oxygen species (ROS) are key to Cd cellular toxicity. Cd-lipid interactions have been less considered. We hypothesized Cd binding to the inner mitochondrial membrane (IMM) phospholipid cardiolipin (CL) and membrane rigidification underlies defective electron transfer by disrupted respiratory supercomplexes (SCs). In Cd-treated rat kidney cortex (rKC) mitoplasts, laurdan (lipid-water interface), and diphenylhexatriene (hydrophobic core) revealed increased and decreased membrane fluidity, respectively. Laurdan-loaded pure CL or IMM biomimetic (40 mol % POPC, 35 mol % DOPE, 20 mol % TOCL, 5 mol % SAPI) nanoliposomes were rigidified by 25 μM Cd, which was confirmed in live-cell imaging of laurdan or di-4-ANEPPDHQ loaded human proximal convoluted tubule (HPCT) cells. Blue native gel electrophoresis evidenced ∼30% loss of I+III2+IVn SC formation after 5 μM Cd for 6 h in HPCTs, which was reversed by CL-binding drug MTP-131/SS-31/elamipretide (0.1 μM), yet α-tocopherol-insensitive. Moreover, MTP-131 attenuated Cd-induced H2O2 (∼30%) and cytochrome c release (∼25%), but not osmotic swelling, in rKC mitochondria as well as Cd-induced ROS (∼25%) in HPCTs. MTP-131 binding to IMM biomimetic nanoliposomes decreased zeta potential, prevented Cd-induced liposome size increase, and membrane rigidification reported by laurdan. Heterologous CRLS1 expression reversed Cd (5 μM, 24 h) cytotoxicity (∼25%) by MTT assay, Cd (5 μM, 3 h)-induced ROS and mitochondrial membrane rigidification by Cd (1 μM, 1 h) in HPCT cells. In summary, we report a novel mechanism for Cd toxicity in which Cd-CL interactions cause IMM rigidification, thereby disrupting correct SC assembly and increasing ROS.

Enhanced Parkin-mediated mitophagy mitigates adverse left ventricular remodelling after myocardial infarction: role of PR-364.

Lizhuo Ai, Juliana de Freitas Germano, Chengqun Huang +15 more

Almost 30% of survivors of myocardial infarction (MI) develop heart failure (HF), in part due to damage caused by the accumulation of dysfunctional mitochondria. Organelle quality control through Parkin-mediated mitochondrial autophagy (mitophagy) is known to play a role in mediating protection against HF damage post-ischaemic injury and remodelling of the subsequent deteriorated myocardium.

Mitochondrial Cardiolipin-Targeted Tetrapeptide, SS-31, Exerts Neuroprotective Effects Within In Vitro and In Vivo Models of Spinal Cord Injury.

Baylen Ravenscraft, Do-Hun Lee, Heqiao Dai +5 more

Spinal cord injury (SCI) affects millions globally, leading to severe motor and sensory deficits with no effective clinical treatment. Cardiolipin (CL), a mitochondria-specific phospholipid, plays a critical role in bioenergetics and apoptosis. Emerging evidence suggests that CL alterations contribute to secondary SCI pathology, but their precise role and underlying mechanisms remain fully understudied. In this study, we investigated the protective effects of SS-31 on CL alteration, neuronal death, tissue damage, and behavioral recovery after SCI using both in vitro and in vivo models, lipidomics analysis, histological evaluation, and behavioral assessments. In vitro investigations used primary spinal cord neuron cultures, challenged with either rotenone or glutamatergic excitotoxicity, with protective capabilities measured via cell death assays and neurite morphological analysis. In vivo investigations used female adult C57Bl/6 mice, challenged with a contusive SCI. The results showed that SS-31 reduced rotenone- and glutamate-induced mitochondrial dysfunction and neuronal death in a dose-dependent manner in vitro. Additionally, SS-31 attenuated rotenone- and glutamate-induced neurite degeneration in vitro. Lipidomics analysis revealed a reduction in CL at 24 h post-SCI in adult mice, which was attenuated by SS-31 in a dose-dependent manner. Consistent with this effect, SS-31 improved behavioral recovery after SCI in adult mice, although it had no significant effect on tissue damage. These findings suggest that CL alteration may play a key role in the pathogenesis of SCI, at least in the C57BL/6 mouse, and as such could be an attractive therapeutic target for ameliorating secondary SCI.

The Application and Molecular Mechanisms of Mitochondria-Targeted Antioxidants in Chemotherapy-Induced Cardiac Injury.

Chih-Jen Liu, Lu-Kai Wang, Fu-Ming Tsai

Chemotherapeutic agents play a crucial role in cancer treatment. However, their use is often associated with significant adverse effects, particularly cardiotoxicity. Drugs such as anthracyclines (e.g., doxorubicin) and platinum-based agents (e.g., cisplatin) cause mitochondrial damage, which is one of the main mechanisms underlying cardiotoxicity. These drugs induce oxidative stress, leading to an increase in reactive oxygen species (ROS), which in turn damage the mitochondria in cardiomyocytes, resulting in impaired cardiac function and heart failure. Mitochondria-targeted antioxidants (MTAs) have emerged as a promising cardioprotective strategy, offering a potential solution. These agents efficiently scavenge ROS within the mitochondria, protecting cardiomyocytes from oxidative damage. Recent studies have shown that MTAs, such as elamipretide, SkQ1, CoQ10, and melatonin, significantly mitigate chemotherapy-induced cardiotoxicity. These antioxidants not only reduce oxidative damage but also help maintain mitochondrial structure and function, stabilize mitochondrial membrane potential, and prevent excessive opening of the mitochondrial permeability transition pore, thus preventing apoptosis and cardiac dysfunction. In this review, we integrate recent findings to elucidate the mechanisms of chemotherapy-induced cardiotoxicity and highlight the substantial therapeutic potential of MTAs in reducing chemotherapy-induced heart damage. These agents are expected to offer safer and more effective treatment options for cancer patients in clinical practice.

Expanded-access use of elamipretide in a newborn with Barth syndrome: a case report.

Laura Ortmann, Danita Velasco, Jason Cole

Barth syndrome (BTHS) is a rare genetic disease, with no approved curative therapies, characterized by abnormally developed cardiolipin, resulting in mitochondrial dysfunction. Cardiomyopathy, a common clinical manifestation of BTHS, often appears in infancy. Elamipretide, an investigational drug that binds to cardiolipin on the inner mitochondrial membrane, leads to improved membrane stability, enhanced adenosine triphosphate production, and reduced reactive oxygen species. This patient case aims to further support elamipretide's role in treating BTHS infants.

New insight for SS‑31 in treating diabetic cardiomyopathy: Activation of mitoGPX4 and alleviation of mitochondria‑dependent ferroptosis.

Lie Xiong, Huilin Hu, Fuxiang Zhu +7 more

SS‑31 is a mitochondria‑targeting antioxidant that exhibits promising therapeutic potential for various diseases; however, its protective effect on diabetic cardiomyopathy (DCM) remains to be elucidated. At present, SS‑31 is considered not only to mitigate cardiolipin oxidative damage, but also to alleviate ferroptosis. The present study aimed to explore SS‑31 as a potential therapeutic strategy for improving DCM by alleviating mitochondria‑dependent ferroptosis. In vitro, H9C2 cells were exposed to 35 mM glucose for 24 h to induce high glucose damage, then were simultaneously treated with 10, 20 or 50 µM SS‑31. In addition, in vivo studies were conducted on diabeticC57BL/6J mice, which were induced to develop DCM over 4 weeks, followed by intraperitoneal injections with 2.5 mg/kg/day SS‑31 for a further 4 weeks. The elevation of serum lactate dehydrogenase and creatine kinase isoenzymes, the reduction of fractional shortening and ejection fraction, the rupture of myocardial fibers and the deposition of collagen indicated the establishment of the DCM mouse model. The results of the present study indicated that SS‑31 effectively alleviated these pathological changes and exhibited significant efficacy in ameliorating mitochondrial dysfunction, such as by promoting adenosine triphosphate generation, improving mitochondrial membrane potential and restoring the mitochondrial ultrastructure. Further experiments suggested that activation of the mitochondrial glutathione (mitoGSH)/mitochondrial glutathione peroxidase 4 (mitoGPX4) pathway and the elimination of mitochondrial ferrous ions may constitute the mechanisms by which SS‑31 treats DCM. Therefore, the present study revealed that mitochondria‑dependent ferroptosis could serve as a pathogenic mechanism of DCM and highlighted that the cardioprotective effects of SS‑31 against DCM involves activation of the mitoGSH/mitoGPX4 pathway. Due to the safety profile and cardiac protective effects of SS‑31, SS‑31 was considered a promising strategy for treating DCM.

Skeletal muscle mitochondrial dysfunction mediated by Pseudomonas aeruginosa quorum-sensing transcription factor MvfR: reversing effects with anti-MvfR and mitochondrial-targeted compounds.

Shifu Aggarwal, Vijay Singh, Arijit Chakraborty +8 more

Sepsis and chronic infections with Pseudomonas aeruginosa, a leading "ESKAPE" bacterial pathogen, are associated with increased morbidity and mortality and skeletal muscle atrophy. The actions of this pathogen on skeletal muscle remain poorly understood. In skeletal muscle, mitochondria serve as a crucial energy source, which may be perturbed by infection. Here, using the well-established backburn and infection model of murine P. aeruginosa infection, we deciphered the systemic impact of the quorum-sensing transcription factor MvfR (multiple virulence factor regulator) by interrogating, 5 days post-infection, its effect on mitochondrial-related functions in the gastrocnemius skeletal muscle and the outcome of the pharmacological inhibition of MvfR function and that of the mitochondrial-targeted peptide, Szeto-Schiller 31 (SS-31). Our findings show that the MvfR perturbs adenosine triphosphate generation, oxidative phosphorylation, and antioxidant response, elevates the production of reactive oxygen species, and promotes oxidative damage of mitochondrial DNA in the gastrocnemius muscle of infected mice. These impairments in mitochondrial-related functions were corroborated by the alteration of key mitochondrial proteins involved in electron transport, mitochondrial biogenesis, dynamics and quality control, and mitochondrial uncoupling. Pharmacological inhibition of MvfR using the potent anti-MvfR lead, D88, we developed, or the mitochondrial-targeted peptide SS-31 rescued the MvfR-mediated alterations observed in mice infected with the wild-type strain PA14. Our study provides insights into the actions of MvfR in orchestrating mitochondrial dysfunction in the skeletal murine muscle, and it presents novel therapeutic approaches for optimizing clinical outcomes in affected patients.

SS-31 treatment ameliorates cardiac mitochondrial morphology and defective mitophagy in a murine model of Barth syndrome.

Silvia Russo, Domenico De Rasmo, Roberta Rossi +2 more

Barth syndrome (BTHS) is a lethal rare genetic disorder, which results in cardiac dysfunction, severe skeletal muscle weakness, immune issues and growth delay. Mutations in the TAFAZZIN gene, which is responsible for the remodeling of the phospholipid cardiolipin (CL), lead to abnormalities in mitochondrial membrane, including alteration of mature CL acyl composition and the presence of monolysocardiolipin (MLCL). The dramatic increase in the MLCL/CL ratio is the hallmark of patients with BTHS, which is associated with mitochondrial bioenergetics dysfunction and altered membrane ultrastructure. There are currently no specific therapies for BTHS. Here, we showed that cardiac mitochondria isolated from TAFAZZIN knockdown (TazKD) mice presented abnormal ultrastructural membrane morphology, accumulation of vacuoles, pro-fission conditions and defective mitophagy. Interestingly, we found that in vivo treatment of TazKD mice with a CL-targeted small peptide (named SS-31) was able to restore mitochondrial morphology in tafazzin-deficient heart by affecting specific proteins involved in dynamic process and mitophagy. This agrees with our previous data showing an improvement in mitochondrial respiratory efficiency associated with increased supercomplex organization in TazKD mice under the same pharmacological treatment. Taken together our findings confirm the beneficial effect of SS-31 in the amelioration of tafazzin-deficient dysfunctional mitochondria in a BTHS animal model.

Challenging and target-based shifting strategies for heart failure treatment: An update from the last decades.

Yuichi Hattori, Kohshi Hattori, Kuniaki Ishii +1 more

Heart failure (HF) is a major global health problem afflicting millions worldwide. Despite the significant advances in therapies and prevention, HF still carries very high morbidity and mortality, requiring enormous healthcare-related expenditure, and the search for new weapons goes on. Following initial treatment strategies targeting inotropism and congestion, attention has focused on offsetting the neurohormonal overactivation and three main therapies, including angiotensin-converting enzyme inhibitors or angiotensin II type 1 receptor antagonists, β-adrenoceptor antagonists, and mineralocorticoid receptor antagonists, have been the foundation of standard treatment for patients with HF. Recently, a paradigm shift, including angiotensin receptor-neprilysin inhibitor, sodium glucose co-transporter 2 inhibitor, and ivabradine, has been added. Moreover, soluble guanylate cyclase stimulator, elamipretide, and omecamtiv mecarbil have come out as a next-generation therapeutic agent for patients with HF. Although these pharmacologic therapies have been significantly successful in relieving symptoms, there is still no complete cure for HF. We may be currently entering a new era of treatment for HF with animal experiments and human clinical trials assessing the value of antibody-based immunotherapy and gene therapy as a novel therapeutic strategy. Such tempting therapies still have some challenges to be addressed but may become a weighty option for treatment of HF. This review article will compile the paradigm shifts in HF treatment over the past dozen years or so and illustrate current landscape of antibody-based immunotherapy and gene therapy as a new therapeutic algorithm for patients with HF.

An injectable mitochondria-targeted nanodrug loaded-hydrogel for restoring mitochondrial function and hierarchically attenuating oxidative stress to reduce myocardial ischemia-reperfusion injury.

Xiaoping Zhang, Yage Sun, Rong Yang +4 more

Timely reperfusion is the common treatment for myocardial infarction. However, ischemia-reperfusion (I/R) therapy can lead to oxidative stress and mitochondrial dysfunction that further aggravate myocardial injury, and no effective therapy is currently available for alleviating myocardial I/R injury. Herein, we engineer a mitochondria-targeted Szeto-Schiller (SS31) peptide modified-amphiphilic polymer (PTPS) that self-assembles into nanomicelles (PTPSCs) for loading cyclosporine A (CsA). The PTPSCs are then encapsulated into a pH/ROS dual responsive injectable hydrogel crosslinked with reversible imine and boronic ester bonds. The loaded PTPSCs are controllably delivered from the hydrogel matrix in response to the low pH and high ROS microenvironment of the I/R heart, thus realizing reconstruction of mitochondrial function and unprecedented hierarchical attenuation of oxidative stress. The boronic ester in the hydrogel consumes the ROS in cardiac microenvironment, and the mitochondria-targeted delivery of CsA is revealed to inhibit mitochondria-mediated apoptosis signaling pathway to prevent cardiomyocyte apoptosis, meanwhile attenuating the mitochondrial ROS output to reduce the level of cytosolic ROS. Additionally, SS31 can also serve as an antioxidant to consume ROS in the mitochondria. In rat model of myocardial I/R injury with administration of this injectable hydrogel, the targeted release of PTPSCs efficiently restores mitochondrial and cardiac function.

Targeting mitochondrial stress with Szeto-Schiller 31 prevents experimental abdominal aortic aneurysm: Crosstalk with endoplasmic reticulum stress.

Miquel Navas-Madroñal, Rafael Almendra-Pegueros, Lidia Puertas-Umbert +8 more

Mitochondrial dysfunction and inflammation contribute to a myriad of cardiovascular diseases. Deleterious crosstalk of mitochondria and persistent endoplasmic reticulum (ER) stress triggers oxidative stress, which is involved in the development of vascular diseases. This study determined if inhibition of mitochondrial stress reduces aneurysm development in angiotensin II (Ang II)-infused apolipoprotein-E-deficient (ApoE-/- ) mice and its effect on ER stress.

Temporal evolution of the heart failure phenotype in Barth syndrome and treatment with elamipretide.

Hani N Sabbah, Carolyn Taylor, Hilary J Vernon

Barth syndrome (BTHS) is a rare genetic disorder caused by pathogenic variants in TAFAZZIN leading to reduced remodeled cardiolipin (CL), a phospholipid essential to mitochondrial function and structure. Cardiomyopathy presents in most patients with BTHS, typically appearing as dilated cardiomyopathy (DCM) in infancy and evolving to hypertrophic cardiomyopathy (HCM) resembling heart failure (HF) with preserved ejection fraction (HFpEF) in some patients ≥12 years. Elamipretide localizes to the inner mitochondrial membrane where it associates with CL, improving mitochondrial function, structure and bioenergetics, including ATP synthesis. Numerous preclinical and clinical studies in BTHS and other forms of HF have demonstrated that elamipretide improves left ventricular relaxation by ameliorating mitochondrial dysfunction, making it well suited for therapeutic use in adolescent and adult patients with BTHS.

Mitochondrial dysfunction in human hypertrophic cardiomyopathy is linked to cardiomyocyte architecture disruption and corrected by improving NADH-driven mitochondrial respiration.

Edgar E Nollet, Inez Duursma, Anastasiya Rozenbaum +11 more

Genetic hypertrophic cardiomyopathy (HCM) is caused by mutations in sarcomere protein-encoding genes (i.e. genotype-positive HCM). In an increasing number of patients, HCM occurs in the absence of a mutation (i.e. genotype-negative HCM). Mitochondrial dysfunction is thought to be a key driver of pathological remodelling in HCM. Reports of mitochondrial respiratory function and specific disease-modifying treatment options in patients with HCM are scarce.

Beneficial effects of SS-31 peptide on cardiac mitochondrial dysfunction in tafazzin knockdown mice.

Silvia Russo, Domenico De Rasmo, Anna Signorile +2 more

Barth Syndrome (BTHS), a genetic disease associated with early-onset cardioskeletal myopathy, is caused by loss-of-function mutations of the TAFAZZIN gene, which is responsible for remodeling the mitochondrial phospholipid cardiolipin (CL). Deregulation of CL biosynthesis and maturation in BTHS mitochondria result in a dramatically increased monolysocardiolipin (MLCL)/CL ratio associated with bioenergetic dysfunction. One of the most promising therapeutic approaches for BTHS includes the mitochondria-targeted tetrapeptide SS-31, which interacts with CL. Here, we used TAFAZZIN knockdown (TazKD) mice to investigate for the first time whether in vivo administration of SS-31 could affect phospholipid profiles and mitochondrial dysfunction. The CL fingerprinting of TazKD cardiac mitochondria obtained by MALDI-TOF/MS revealed the typical lipid changes associated with BTHS. TazKD mitochondria showed lower respiratory rates in state 3 and 4 together with a decreased in maximal respiratory rates. Treatment of TazKD mice with SS-31 improved mitochondrial respiratory capacity and promoted supercomplex organization, without affecting the MLCL/CL ratio. We hypothesize that SS-31 exerts its effect by influencing the function of the respiratory chain rather than affecting CL directly. In conclusion, our results indicate that SS-31 have beneficial effects on improving cardiac mitochondrial dysfunction in a BTHS animal model, suggesting the peptide as future pharmacologic agent for therapy.

Aging Increases Susceptibility to Develop Cardiac Hypertrophy following High Sugar Consumption.

Ana P Valencia, Jeremy A Whitson, Shari Wang +4 more

Aging and poor diet are independent risk factors for heart disease, but the impact of high-sucrose (HS) consumption in the aging heart is understudied. Aging leads to impairments in mitochondrial function that result in muscle dysfunction (e.g., cardiac remodeling and sarcopenia). We tested whether HS diet (60%kcal sucrose) would accelerate muscle dysfunction in 24-month-old male CB6F1 mice. By week 1 on HS diet, mice developed significant cardiac hypertrophy compared to age-matched chow-fed controls. The increased weight of the heart persisted throughout the 4-week treatment, while body weight and strength declined more rapidly than controls. We then tested whether HS diet could worsen cardiac dysfunction in old mice and if the mitochondrial-targeted drug, elamipretide (ELAM), could prevent the diet-induced effect. Old and young mice were treated with either ELAM or saline as a control for 2 weeks, and provided with HS diet or chow on the last week. As demonstrated in the previous experiment, old mice had age-related cardiac hypertrophy that worsened after one week on HS and was prevented by ELAM treatment, while the HS diet had no detectable effect on hypertrophy in the young mice. As expected, mitochondrial respiration and reactive oxygen species (ROS) production were altered by age, but were not significantly affected by HS diet or ELAM. Our findings highlight the vulnerability of the aged heart to HS diet that can be prevented by systemic targeting of the mitochondria with ELAM.

Structure-activity relationships of mitochondria-targeted tetrapeptide pharmacological compounds.

Wayne Mitchell, Jeffrey D Tamucci, Emery L Ng +6 more

Mitochondria play a central role in metabolic homeostasis, and dysfunction of this organelle underpins the etiology of many heritable and aging-related diseases. Tetrapeptides with alternating cationic and aromatic residues such as SS-31 (elamipretide) show promise as therapeutic compounds for mitochondrial disorders. In this study, we conducted a quantitative structure-activity analysis of three alternative tetrapeptide analogs, benchmarked against SS-31, that differ with respect to aromatic side chain composition and sequence register. We present the first structural models for this class of compounds, obtained with Nuclear Magnetic Resonance (NMR) and molecular dynamics approaches, showing that all analogs except for SS-31 form compact reverse turn conformations in the membrane-bound state. All peptide analogs bound cardiolipin-containing membranes, yet they had significant differences in equilibrium binding behavior and membrane interactions. Notably, analogs had markedly different effects on membrane surface charge, supporting a mechanism in which modulation of membrane electrostatics is a key feature of their mechanism of action. The peptides had no strict requirement for side chain composition or sequence register to permeate cells and target mitochondria in mammalian cell culture assays. All four peptides were pharmacologically active in serum withdrawal cell stress models yet showed significant differences in their abilities to restore mitochondrial membrane potential, preserve ATP content, and promote cell survival. Within our peptide set, the analog containing tryptophan side chains, SPN10, had the strongest impact on most membrane properties and showed greatest efficacy in cell culture studies. Taken together, these results show that side chain composition and register influence the activity of these mitochondria-targeted peptides, helping provide a framework for the rational design of next-generation therapeutics with enhanced potency.

SS31 Ameliorates Oxidative Stress via the Restoration of Autophagic Flux to Protect Aged Mice From Hind Limb Ischemia.

Qiaoyun Yang, Chunqiu Li, Qingwei Chen

Oxidative stress and impaired autophagic flux play important roles in the development of peripheral artery disease (PAD). SS31 is considered an important antioxidant peptide and autophagy regulator. We aimed to investigate the role of SS31 in PAD myopathy and its possible mechanism both in vivo and in vitro.