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Effect of alisporivir (a mitochondrial permeability transition pore inhibitor) on the development of mitochondrial dysfunction under hyperglycemic conditions in the primary culture of mouse lung endothelial cells was investigated in this work. We demonstrated that hyperglycemia (30 mM glucose for 24 h) leads to the decrease in viability of the pulmonary endotheliocytes, causes mitochondrial dysfunction manifested by the drop in membrane potential and increase in superoxide anion generation as well as facilitates opening of the mitochondrial permeability transition pore (MPT pore). Incubation of endothelial cells with 5 µM alisporivir under hyperglycemic conditions leads to the increase in cell viability, restoration of the membrane potential level and of the MPT pore opening activity to control values. Hyperglycemia causes increased mitophagy in the lung endothelial cells: we observed increase in the degree of colocalization of mitochondria and lysosomes and upregulation of the Parkin gene expression. Alisporivir restores these parameters back to the levels observed in the control cells. Hyperglycemia results in the increase in the expression of the Drp1 gene in endotheliocytes responsible for synthesis of the protein involved in the process of mitochondria fission. Alisporivir does not significantly alter expression of the genes. The paper discusses mechanisms of the effect of alisporivir on mitochondrial dysfunction in murine pulmonary endotheliocytes under conditions of hyperglycemia. [ABSTRACT FROM AUTHOR]

We studied the effect of the mitochondrial calcium-dependent pore (MPT pore) inhibitor alisporivir (5 mg/kg per day for 4 weeks) on the parameters of calcium ion transport and the intensity of mitophagy in mitochondria of the heart and skeletal muscles of dystrophin-deficient C57BL/10ScSn-mdx mice. Alisporivir increased the rate of calcium uptake by skeletal muscle mitochondria of mdx mice, which was accompanied by changes in the level of the MCU and MCUb subunits of the calcium uniporter. At the same time, the intensity of calcium uniport in the heart mitochondria did not change. Alisporivir was found to reduce the expression of Pink1 and Parkin genes regulating the intensity of mitophagy in skeletal muscles of mdx mice, but did not affect the expression of these genes in the heart. This effect of alisporivir was accompanied by fragmentation and a decrease in the mean size of organelles. Possible mitochondrion-related mechanisms of the protective effect of alisporivir on the skeletal muscle and heart cells are discussed. [ABSTRACT FROM AUTHOR]

This paper reports the results of a computational nanochemistry study of the chemical reactivities and bioactivity properties of two antimicrobial peptides using a CDFT-based computational peptidology (CDFT-CP) methodology, which is derived from the combination of the chemical reactivity descriptors derived from conceptual density functional theory (CDFT) and some cheminformatics tools useful in the design of therapeutic drugs. This is complemented by an examination of the bioactivity and pharmacokinetics indices of the peptides in relation to the ADMET (absorption, distribution, metabolism, excretion, and toxicity) features. These findings provide further evidence of the superiority of the MN12SX density functional in fulfilling the Janak and ionization energy theorems using an earlier proposed KID methodology for validation. This has proven to be beneficial in accurately predicting CDFT indices, which is of help in the understanding of the chemical reactivity. The computational pharmacokinetics study revealed the potential ability of both cyclopeptides as therapeutic drugs through the interaction with different target receptors. The ADMET indices confirmed this assertion through the absence of toxicity and good absorption and distribution properties.

Supporting mitochondrial function is one of the therapeutic strategies that improve the functioning of skeletal muscle in Duchenne muscular dystrophy (DMD). In this work, we studied the effect of a non-immunosuppressive inhibitor of mitochondrial permeability transition pore (MPTP) alisporivir (5 mg/kg/day), reducing the intensity of the necrotic process and inflammation in skeletal muscles on the cardiac phenotype of dystrophin-deficient mdx mice. We found that the heart mitochondria of mdx mice show an increase in the intensity of oxidative phosphorylation and an increase in the resistance of organelles to the MPT pore opening. Alisporivir had no significant effect on the hyperfunctionalization of the heart mitochondria of mdx mice, and the state of the heart mitochondria of wild-type animals did not affect the dynamics of organelles but significantly suppressed mitochondrial biogenesis and reduced the amount of mtDNA in the heart muscle. Moreover, alisporivir suppressed mitochondrial biogenesis in the heart of wild-type mice. Alisporivir treatment resulted in a decrease in heart weight in mdx mice, which was associated with a significant modification of the transmission of excitation in the heart. The latter was also noted in the case of WT mice treated with alisporivir. The paper discusses the prospects for using alisporivir to correct the function of heart mitochondria in DMD.

Diabetes mellitus is a systemic metabolic disorder associated with mitochondrial dysfunction, with the mitochondrial permeability transition (MPT) pore opening being considered as one of its possible mechanisms. The effect of alisporivir, a non-immunosuppressive cyclosporin derivative and a selective inhibitor of the MPT pore opening, on the ultrastructure and functions of the heart mitochondria of mice with diabetes mellitus induced by a high-fat diet combined with streptozotocin injections was studied. The treatment of diabetic animals with alisporivir (2.5 mg/kg ip for 20 days) increased the rate of glucose clearance during the glucose tolerance test. The blood glucose level and the indicator of heart rate in alisporivir-treated diabetic mice tended to restore. An electron microscopy analysis showed that alisporivir prevented mitochondrial swelling and ultrastructural alterations in cardiomyocytes of diabetic mice. Alisporivir canceled the diabetes-induced increases in the susceptibility of heart mitochondria to the MPT pore opening and the level of lipid peroxidation products, but it did not affect the decline in mitochondrial oxidative phosphorylation capacity. The mRNA expression levels of Pink1 and Parkin in the heart tissue of alisporivir-treated diabetic mice were elevated, suggesting the stimulation of mitophagy. In parallel, alisporivir decreased the level of mtDNA in the heart tissue. These findings suggest that targeting the MPT pore opening by alisporivir alleviates the development of mitochondrial dysfunction in the diabetic heart. The cardioprotective effect of the drug in diabetes can be mediated by the induction of mitophagy and the inhibition of lipid peroxidation in the organelles.

Previously, the cyclophilin inhibitors cyclosporine (CsA) and alisporivir (ALV) were shown to inhibit the replication of diverse RNA viruses, including arteriviruses and coronaviruses, which both belong to the order Nidovirales. In this study, we aimed to identify arterivirus proteins involved in the mode of action of cyclophilin inhibitors and to investigate how these compounds inhibit arterivirus RNA synthesis in the infected cell. Repeated passaging of the arterivirus prototype equine arteritis virus (EAV) in the presence of CsA revealed that reduced drug sensitivity is associated with the emergence of adaptive mutations in nonstructural protein 5 (nsp5), one of the transmembrane subunits of the arterivirus replicase polyprotein. Introduction of singular nsp5 mutations (nsp5 Q21R, Y113H, or A134V) led to an α2- fold decrease in sensitivity to CsA treatment, whereas combinations of mutations further increased EAV's CsA resistance. The detailed experimental characterization of engineered EAV mutants harboring CsA resistance mutations implicated nsp5 in arterivirus RNA synthesis. Particularly, in an in vitro assay, EAV RNA synthesis was far less sensitive to CsA treatment when nsp5 contained the adaptive mutations mentioned above. Interestingly, for increased sensitivity to the closely related drug ALV, CsA-resistant nsp5 mutants required the incorporation of an additional adaptive mutation, which resided in nsp2 (H114R), another transmembrane subunit of the arterivirus replicase. Our study provides the first evidence for the involvement of nsp2 and nsp5 in the mechanism underlying the inhibition of arterivirus replication by cyclophilin inhibitors. [ABSTRACT FROM AUTHOR]

Alisporivir (ALV) is an 11‐amino‐acid hydrophobic cyclic peptide with N‐methyl‐ d‐alanine and N‐ethyl‐ l‐valine (NEV) residues at positions 3 and 4, respectively. ALV is a non‐immunosuppressive cyclosporin A (CsA) derivative. This inhibitor targets cyclophilins (Cyps), a family of proteins with peptidyl‐prolyl cis/trans isomerase enzymatic activity. Cyps act as protein chaperones and are involved in numerous cellular functions. Moreover, Cyps have been shown to be an essential cofactor for the replication of many viruses, including Hepatitis C virus and Human immunodeficiency virus, and have also been shown to be involved in mitochondrial diseases. For these reasons, cyclophilins represent an attractive drug target. The structure of ALV in complex with cyclophilin A (CypA), the most abundant Cyp in humans, has been determined at 1.5 Å resolution. This first structure of the CypA–ALV complex shows that the binding of ALV is highly similar to that of CsA. The high resolution allowed the unambiguous determination of the conformations of residues 3 and 4 in ALV when bound to its target. In particular, the side‐chain conformation of NEV4 precludes the interaction of the CypA–ALV complex with calcineurin, a cellular protein phosphatase involved in the immune response, which explains the non‐immunosuppressive property of ALV. This study provides detailed molecular insights into the CypA–ALV interaction. [ABSTRACT FROM AUTHOR]

Cyclophilins (Cyps) belong to the family of peptidyl-prolyl isomerases (PPIases). The PPIase activity of most Cyps is inhibited by the immunosuppressive drug cyclosporin A and several of its non-immunosuppressive analogs, which can also block the replication of nidoviruses (arteriviruses and coronaviruses). Cyclophilins have been reported to play an essential role in the replication of several other RNA viruses, including human immunodeficiency virus-1, hepatitis C virus, and influenza A virus. Likewise, the replication of various nidoviruses was reported to depend on Cyps or other PPIases. This review summarizes our current understanding of this class of nidovirus-host interactions, including the potential function of in particular CypA and the inhibitory effect of Cyp inhibitors. Also the involvement of the FK-506-binding proteins and parvulins is discussed. The nidovirus data are placed in a broader perspective by summarizing the most relevant data on Cyp interactions and Cyp inhibitors for other RNA viruses. [ABSTRACT FROM AUTHOR]

DEB025 (alisporivir) is a synthetic cyclosporine with inhibitory activity against human immunodeficiency virus type-1 (HIV-1) and hepatitis C virus (HCV). It binds to cyclophilin A (CypA) and blocks essential functions of CypA in the viral replication cycles of both viruses. DEB025 inhibits clinical HIV-1 isolates in vitro and decreases HIV-1 virus load in the majority of patients. HIV-1 isolates being naturally resistant to DEB025 have been detected in vitro and in nonresponder patients. By sequence analysis of their capsid protein (CA) region, two amino acid polymorphisms that correlated with DEB025 resistance were identified: H87Q and I91N, both located in the CypA-binding loop of the CA protein of HIV-1. The H87Q change was by far more abundant than I91N. Additional polymorphisms in the CypA-binding loop (positions 86, 91 and 96), as well as in the N-terminal loop of CA were detected in resistant isolates and are assumed to contribute to the degree of resistance. These amino acid changes may modulate the conformation of the CypA-binding loop of CA in such a way that binding and/or isomerase function of CypA are no longer necessary for virus replication. The resistant HIV-1 isolates thus are CypA-independent.

Antiviral therapeutics with existing clinical safety profiles would be highly desirable in an outbreak situation, such as the 2013-2016 emergence of Ebola virus (EBOV) in West Africa. Although, the World Health Organization declared the end of the outbreak early 2016, sporadic cases of EBOV infection have since been reported. Alisporivir is the most clinically advanced broad-spectrum antiviral that functions by targeting a host protein, cyclophilin A (CypA). A modest antiviral effect of alisporivir against contemporary (Makona) but not historical (Mayinga) EBOV strains was observed in tissue culture. However, this effect was not comparable to observations for an alisporivir-susceptible virus, the flavivirus tick-borne encephalitis virus. Thus, EBOV does not depend on (CypA) for replication, in contrast to many other viruses pathogenic to humans. [ABSTRACT FROM AUTHOR]

Major advances have revolutionized the HCV antiviral treatment field, with interferon-free combinations of direct-acting antivirals (DAAs) resulting into success rates of > 90% for all HCV genotypes. Nevertheless, viral eradication at a global level stills remains challenging, stimulating the continued search for new affordable pan-genotypic drugs. To overcome selection of drug resistant variants, targeting host proteins can be an attractive mechanism of action. Alisporivir (Debio 025) is a potent pan-genotypic host-targeting antiviral agent, acting on cyclophilin A, which is necessary for HCV replication. The efficacy and safety of three different oral doses of alisporivir in combination with pegylated interferon-α2a given over a period of four weeks, was investigated in a randomized, double-blind and placebo-controlled phase IIa clinical trial, in 90 treatment-naïve subjects infected with chronic hepatitis C, wherefrom 58 HCV1b samples were selected for genetic sequencing purposes. Sequencing results were used to study the HCV genome for amino acid changes potentially related with selective pressure and resistance to alisporivir. By comparing baseline and on-treatment sequences, a large variation in proportion of amino acid changes was detected in all treatment arms. The NS5A variant D320E, which was previously identified during in vitro resistance selection and resulted in 3.6-fold reduced alisporivir susceptibility, emerged in two subjects in the alisporivir monotherapy arm. However, emergence of D320E appeared to be associated only with concurrent viral load rebound in one subject with 0.8 log 10 IU/ml increase in HCV RNA. In general, for all datasets, low numbers of positions under positive selective pressure were observed, with no significant differences between naïve and treated sequences. Additionally, incomplete sequence information for some of the 22 patients and the low number of individuals per treatment arm, is limiting the power to assess the association of alisporivir or interferon treatment with the observed amino acid changes. [ABSTRACT FROM AUTHOR]

Alisporivir (ALV) is an oral, investigational host-targeting agent, with pangenotypic activity against hepatitis C virus (HCV). This randomized, double-blind, placebo-controlled, Phase II study explored the efficacy and safety of ALV with peginterferon- α2a/ribavirin (PR) in patients with chronic HCV genotype 1 infection in whom prior PR had failed (43% relapsers, 34% null responders and 23% partial responders). Four-hundred-and-fifty-nine patients were randomized (1:1:1:1) to ALV 600 mg once daily (QD), ALV 800 mg QD, ALV 400 twice daily (BID) or placebo plus PR for 48 weeks. When the global ALV trial programme was put on clinical hold, all patients in this study had received ≥31 weeks of randomized treatment; patients completed 48 weeks on PR alone. All ALV groups demonstrated superior rates of complete early virologic response ( cEVR; primary endpoint) vs PR alone ( P ≤ 0.0131), with highest cEVR rate seen with ALV 400 mg BID (74% vs 36% with PR alone; P < 0.0001). Respective SVR12 rates (key secondary endpoint) were 65% vs 26% in prior relapsers, 63% vs 5% in partial responders and 68% vs 3% in null responders. In patients who received >40 weeks of randomized treatment, the SVR12 rate was 89% for ALV 400 mg BID vs 30% for PR alone ( P = 0.0053). Rates of viral breakthrough and relapse were lowest with ALV 400 mg BID. One case of pancreatitis (fully recovered) occurred with ALV/PR. Common AEs were headache, fatigue, anaemia, neutropenia and nausea. Hypertension was infrequent, but more common with ALV. ALV merits further investigation in interferon-free regimens in combination with direct-acting antiviral agents. [ABSTRACT FROM AUTHOR]

The paper considers the effect of the MPT pore inhibitor cyclosporin A (CsA) and its non-immunosuppressive analogue alisporivir (Ali) on the functioning of rat skeletal muscle mitochondria. We have shown that both agents at a standard in vitro concentration of 1 μM increase the calcium capacity of organelles and have no effect on the parameters of oxidative phosphorylation. However, an increase in their concentration to 5 μM leads to the suppression of oxygen consumption by mitochondria, which is more pronounced in the case of Ali. This effect is accompanied by a decrease in the membrane potential of organelles and, apparently, is based on the inhibition of electron transport along the mitochondrial respiratory chain due to limited mobility of coenzyme Q. We have noted that both agents do not affect the production of hydrogen peroxide by isolated mitochondria. NMR spectroscopy and molecular dynamics simulation did not reveal significant differences in the structure and backbone flexibility of CsA and Ali. Both agents decrease the overall fluidity of the membrane of DPPC liposomes, inducing an increase in laurdan generalized polarization parameter. A similar effect was also found in the case of mitochondrial membranes. We suggested that these effects of CsA and Ali, associated with their lipophilic nature and the ability to accumulate in the lipid phase of membranes, may cause a decrease in the efficiency of electron transport in the respiratory chain of mitochondria and suppression of the bioenergetics of these organelles. [Display omitted] • CsA and alisporivir can reduce the efficiency of the mitochondrial OXPHOS system. • Both agents are able to inhibit the transport of electrons along the respiratory chain. • CsA and alisporivir decrease the overall fluidity of the DPPC and mitochondrial membrane. • Both agents may affect the mobility of hydrophobic components of the respiratory chain. [ABSTRACT FROM AUTHOR]

In vitro data suggest that alisporivir is a substrate and inhibitor of CYP3A4 and P-gp. Hence, the potential for drug-drug interactions when alisporivir is co-administered with CYP3A4 and/or P-gp inhibitors such as ketoconazole, azithromycin and CYP3A4 inducers such as rifampin were evaluated in three separate clinical studies. Co-administration with ketoconazole (a strong CYP3A4 inhibitor) increased the Cmax, AUC and terminal elimination half-life of alisporivir by approximately two-, eight- ,and threefold, respectively. Co-administration with azithromycin (a putative weak CYP3A4 inhibitor and substrate) had no impact on the Cmax and AUC of alisporivir. Rifampin (a CYP3A4 inducer) caused an approximate 90% reduction in alisporivir Cmax and AUC and a fourfold reduction in alisporivir terminal elimination half-life. Alisporivir as an inhibitor of CYP3A4 caused a 39% increase in azithromycin exposure. The results from these studies establish alisporivir as a sensitive CYP3A4 substrate in vivo. Consequently, co-administered potent CYP3A4 inhibitors and inducers are likely to cause clinically significant changes in the exposure to alisporivir. [ABSTRACT FROM AUTHOR]

Summary The cyclophilins are a group of proteins with peptidyl-prolyl isomerase enzymatic activity, localised in different cellular compartments and involved in a variety of functions related to cell metabolism and energy homeostasis, having enhanced expression in inflammation or malignancy. Cyclophilin A (CypA), the most abundantly expressed cyclophilin, is present mainly in the cytoplasm and is a host factor involved in the life cycle of multiple viruses. The extracellular fractions of CypA and CypB are potent pro-inflammatory mediators. CypD, located in mitochondria, is a key regulator of mitochondrial permeability transition pores, and is critical for necrotic cell death. Cyclosporines are the prototype cyclophilin inhibitors. Cyclic peptides, which bind and inhibit cyclophilins without having immunosuppressive properties, have been generated by chemical modifications of cyclosporin A. In addition, cyclophilin inhibitors that are structurally different from cyclosporines have been synthesized. The involvement of cyclophilins in the pathogenesis of different liver diseases has been established using both in vitro and in vivo investigations, thus indicating that cyclophilin inhibition may be of therapeutic benefit. This review summarises the evidence for potential therapeutic applications of non-immunosuppressive cyclophilin inhibitors, alone or in combination with other agents, in virus-induced liver diseases like hepatitis C, B or Delta, liver inflammation and fibrosis, acetaminophen-induced liver toxicity and hepatocellular carcinoma. [ABSTRACT FROM AUTHOR]

Alisporivir is a novel cyclophilin-binding molecule with potent anti-hepatitis C virus (HCV) activity. In vitro data from human liver microsomes suggest that alisporivir is a substrate and a time-dependent inhibitor (TDI) of CYP3A4. The aim of the current work was to develop a novel physiologically based pharmacokinetic (PBPK) model to quantitatively assess the magnitude of CYP3A4 mediated drug–drug interactions with alisporivir as the substrate or victim drug. Towards that, a Simcyp PBPK model was developed by integrating in vitro data with in vivo clinical findings to characterize the clinical pharmacokinetics of alisporivir and further assess the magnitude of drug–drug interactions. Incorporated with absorption, distribution, elimination, and TDI data, the model accurately predicted AUC, C max , and t max values after single or multiple doses of alisporivir with a prediction deviation within ±32%. The model predicted an alisporivir AUC increase by 9.4-fold and a decrease by 86% when alisporivir was co-administrated with ketoconazole (CYP3A4 inhibitor) or rifampin (CYP3A4 inducer), respectively. Predictions were within ±20% of the observed changes. In conclusion, the PBPK model successfully predicted the alisporivir PK and the magnitude of drug–drug interactions. [ABSTRACT FROM AUTHOR]

The emergence of Plasmodium falciparum resistance raises an urgent need to find new antimalarial drugs. Here, we report the rational repurposing of the anti-hepatitis C virus drug, alisporivir, a nonimmunosuppressive analog of cyclosporin A, against artemisinin-resistant strains of P. falciparum. In silico docking studies and molecular dynamic simulation predicted strong interaction of alisporivir with Pf Cyclophilin 19B, confirmed through biophysical assays with a K d value of 354.3 nM. Alisporivir showed potent antimalarial activity against chloroquine-resistant ( Pf RKL-9 with resistance index [Ri] 2.14 ± 0.23) and artemisinin-resistant ( Pf Kelch13 R539T with Ri 1.15 ± 0.04) parasites. The Ri is defined as the ratio between the IC 50 values of the resistant line to that of the sensitive line. To further investigate the mechanism involved, we analyzed the expression level of Pf Cyclophilin 19B in artemisinin-resistant P. falciparum ( Pf Kelch13 R539T ). Semiquantitative real-time transcript, Western blot, and immunofluorescence analyses confirmed the overexpression of Pf Cyclophilin 19B in Pf Kelch13 R539T . A 50% inhibitory concentration in the nanomolar range, together with the targeting of Pf Cyclophilin 19B, suggests that alisporivir can be used in combination with artemisinin. Since artemisinin resistance slows the clearance of ring-stage parasites, we performed a ring survival assay on artemisinin-resistant strain Pf Kelch13 R539T and found significant decrease in parasite survival with alisporivir. Alisporivir was found to act synergistically with dihydroartemisinin and increase its efficacy. Furthermore, alisporivir exhibited antimalarial activity in vivo . Altogether, with the rational target-based Repurposing of alisporivir against malaria, our results support the hypothesis that targeting resistance mechanisms is a viable approach toward dealing with drug-resistant parasite.

Hepatitis C genotype 2 and 3 accounts for a significant number of HCV infected patients around the world. The combination of peginterferon alpha and ribavirin (PEG-IFN/RBV) demonstrated favourable results in treatment of genotype 2 and 3 infected patients with sustained virological responses rates of up to 80 %. In 2011, the first direct acting antivirals (DAA) have been approved but so far only for genotype 1. Several other antivirals are currently tested in clinical trials. Two compounds demonstrated promising results in patients with genotype 2 and 3. Sofosbuvir (SOF), a NS5B polymerase inhibitor, proved to be effective even without PEG-IFN and approval of an interferon-free regimen is foreseeable. Alisporivir (ALV), a host-targeting antiviral demonstrated encouraging results in phase-I and -II trials in genotype 2 and 3 patients and offers a new mechanism of action. However, further trials are needed to prove long-term safety and the efficacy in difficult-to-treat patients. [ABSTRACT FROM AUTHOR]

Highlights: [•] Host-targeting agents (HTAs) typically create an activated antiviral state within the host. [•] HTAs act directly upon cellular receptors, enzymes, and cofactors for hepatitis C virus (HCV) infection. [•] Alisporivir targets cyclophilin A and is the most advanced HTA against HCV. [•] HTAs combined with direct-acting antivirals may be needed for hard-to-treat HCV patient populations. [•] Further development of HTAs could address new and emerging infections. [Copyright &y& Elsevier]

Affecting 2-3% of the world's population, hepatitis C is a common viral infection which is a significant cause of morbidity and mortality. Hepatitis C genotype 1 is the dominant viral genotype among Western patients. For the last 20 years, in the era of interferon-based therapy, it was far more difficult to treat relative to genotypes 2 and 3. Accordingly, a significant focus of research was on new antiviral agents for the dominant genotype 1 patient. Now, as promising specific treatments are being introduced for genotype 1, the attention of clinicians and researchers has turned back to the 50-70 million patients infected with a nongenotype 1 hepatitis C. Furthermore, after recent, larger randomized trials, we have realized that genotype 2 is truly interferon sensitive while genotype 3 patients are far less successful with therapy. In this fundamentally altered landscape, genotype 3 is now potentially the most difficult to treat genotype and an area of intense research for new drug development. Herein we review the virology, natural history and the treatment of genotype 3 hepatitis C. [ABSTRACT FROM AUTHOR]

DEB025 (alisporivir) is a synthetic cyclosporine with inhibitory activity against human immunodeficiency virus type-1 (HIV-1) and hepatitis C virus (HCV). It binds to cyclophilin A (CypA) and blocks essential functions of CypA in the viral replication cycles of both viruses. DEB025 inhibits clinical HIV-1 isolates in vitro and decreases HIV-1 virus load in the majority of patients. HIV-1 isolates being naturally resistant to DEB025 have been detected in vitro and in nonresponder patients. By sequence analysis of their capsid protein (CA) region, two amino acid polymorphisms that correlated with DEB025 resistance were identified: H87Q and I91N, both located in the CypA-binding loop of the CA protein of HIV-1. The H87Q change was by far more abundant than I91N. Additional polymorphisms in the CypA-binding loop (positions 86, 91 and 96), as well as in the N-terminal loop of CA were detected in resistant isolates and are assumed to contribute to the degree of resistance. These amino acid changes may modulate the conformation of the CypA-binding loop of CA in such a way that binding and/or isomerase function of CypA are no longer necessary for virus replication. The resistant HIV-1 isolates thus are CypA-independent. [ABSTRACT FROM AUTHOR]

Of all hepatitis C virus patients, those with cirrhosis are most in need of treatment owing to increased morbidity and mortality. Treatment with pegylated interferon and ribavirin (PEG-IFN/RBV) has clearly shown the benefits of successful treatment by improving fibrosis, causing the regression of cirrhosis and reducing and preventing cirrhosis-related complications. However, the sustained virological response ( SVR) is lower in patients with cirrhosis. First generation protease inhibitors (boceprevir and telaprevir) in combination with PEG-IFN/RBV are a major advancement in the treatment of both naïve and treatment-experienced genotype 1 patients. In naïve patients, the SVR rate with the triple regimen with boceprevir increased by 14% in patients with severe fibrosis or cirrhosis compared to PEG- IFN/ RBV compared by 30% in patients with mild or moderate fibrosis. The SVR rate of the triple regimen with telaprevir increased by 10-30% compared to PEG- IFN/ RBV in patients with severe fibrosis or cirrhosis and by nearly 30% in patients with mild or moderate fibrosis. The greatest benefits seem to be found in patients with cirrhosis who have relapsed, and is limited in prior non-responder patients. Thus, the choice of triple therapy in the latter should be considered in relation to the increase in side effects. There are no data on the efficacy of the triple regimen in patients with decompensated cirrhosis. Results in real-life settings show that patients with cirrhosis need to be carefully followed-up during treatment due to the increase in side effects that are greater than in clinical studies. Next generation DAAs and PEG- IFN/ RBV appear to be more effective and have fewer side effects in patients with cirrhosis. Ultimately, an interferon-free regimen of DAAs combinations will probably provide a SVR in patients with cirrhosis and will probably be proposed in patients with more advanced or decompensated cirrhosis. [ABSTRACT FROM AUTHOR]

Cyclophilin (Cyp) inhibitors are host targeting antivirals binding proteins essential for hepatitis C virus (HCV) replication. The first known Cyp inhibitor-cyclosporin A was able to enhance anti-viral effect of interferon alfa (IFN-alfa) plus ribavirin (RBV), but because of contrary immunosuppressive properties was insufficient to support use in HCV infected patients. Preclinical studies using non-immunosuppressive Cyp inhibitors, Debio 025, NIM811 and SCY-635 demonstrated potent anti-HCV effect. The most advanced in clinical trial Debio 025 (Alisporivir, ALV) is studied in ongoing phase 3 clinical trial. Phase 1 and 2 studies confirmed that addition of ALV to PegIFN-alfa and RBV in HCV genotype 1 infected improved sustained viral response rate up to 75 %. Ongoing studies are expected to support efficacy of interferon-free regimen containing ALV in genotype 2/3 infected patients, improvement of efficacy in non-responders to previous standard therapy and possible rescue therapy after failure of direct acting antivirals. [ABSTRACT FROM AUTHOR]

Hepatitis C (HCV) therapy is currently undergoing a revolution with the development of new classes of Direct Acting Antivirals (DAAs) with distinct mechanisms of action, potency, resistance patterns and significantly less side effects compared to current standard of care therapies. Our patients have struggled with interferon based therapies for the last 2 decades, but now we are at a turning point with the development of new non-interferon combinations of DAAs. These new molecules have demonstrated to be effective, safe and most importantly have shown the capacity to achieve a sustained virological response in the absence of interferon. This article summarizes the available published clinical trials that are rapidly contributing to our understanding of how we might need to combine these new antivirals to achieve the highest rates of cure in HCV patients who are treatment naïve, non-responders or cirrhotic, across all genotypes. [ABSTRACT FROM AUTHOR]

Mitigation of calcium-dependent destruction of skeletal muscle mitochondria is considered as a promising adjunctive therapy in Duchenne muscular dystrophy (DMD). In this work, we study the effect of intraperitoneal administration of a non-immunosuppressive inhibitor of calcium-dependent mitochondrial permeability transition (MPT) pore alisporivir on the state of skeletal muscles and the functioning of mitochondria in dystrophin-deficient mdx mice. We show that treatment with alisporivir reduces inflammation and improves muscle function in mdx mice. These effects of alisporivir were associated with an improvement in the ultrastructure of mitochondria, normalization of respiration and oxidative phosphorylation, and a decrease in lipid peroxidation, due to suppression of MPT pore opening and an improvement in calcium homeostasis. The action of alisporivir was associated with suppression of the activity of cyclophilin D and a decrease in its expression in skeletal muscles. This was observed in both mdx mice and wild-type animals. At the same time, alisporivir suppressed mitochondrial biogenesis, assessed by the expression of Ppargc1a, and altered the dynamics of organelles, inhibiting both DRP1-mediated fission and MFN2-associated fusion of mitochondria. The article discusses the effects of alisporivir administration and cyclophilin D inhibition on mitochondrial reprogramming and networking in DMD and the consequences of this therapy on skeletal muscle health. [ABSTRACT FROM AUTHOR]

Diabetes mellitus is a systemic metabolic disorder associated with mitochondrial dysfunction, with mitochondrial permeability transition (MPT) pore opening being recognized as one of its pathogenic mechanisms. Alisporivir has been recently identified as a non-immunosuppressive analogue of the MPT pore blocker cyclosporin A and has broad therapeutic potential. The purpose of the present work was to study the effect of alisporivir (2.5 mg/kg/day i.p.) on the ultrastructure and functions of the skeletal muscle mitochondria of mice with diabetes mellitus induced by a high-fat diet combined with streptozotocin injections. The glucose tolerance tests indicated that alisporivir increased the rate of glucose utilization in diabetic mice. An electron microscopy analysis showed that alisporivir prevented diabetes-induced changes in the ultrastructure and content of the mitochondria in myocytes. In diabetes, the ADP-stimulated respiration, respiratory control, and ADP/O ratios and the level of ATP synthase in the mitochondria decreased, whereas alisporivir treatment restored these indicators. Alisporivir eliminated diabetes-induced increases in mitochondrial lipid peroxidation products. Diabetic mice showed decreased mRNA levels of Atp5f1a, Ant1, and Ppif and increased levels of Ant2 in the skeletal muscles. The skeletal muscle mitochondria of diabetic animals were sensitized to the MPT pore opening. Alisporivir normalized the expression level of Ant2 and mitochondrial susceptibility to the MPT pore opening. In parallel, the levels of Mfn2 and Drp1 also returned to control values, suggesting a normalization of mitochondrial dynamics. These findings suggest that the targeting of the MPT pore opening by alisporivir is a therapeutic approach to prevent the development of mitochondrial dysfunction and associated oxidative stress in the skeletal muscles in diabetes. [ABSTRACT FROM AUTHOR]

Simple Summary: Diabetes mellitus as a systemic metabolic disease is one of the most serious threats to global health in this century. Diabetic cardiomyopathy is increasingly recognized as one of the most important complications of the disease, which is associated with impaired cell energy metabolism and damage to mitochondria in cardiomyocytes. Therefore, targeting mitochondrial dysfunction by pharmacological agents can be used as a therapeutic strategy in diabetic heart disease. The aim of the work was to study the effect of the mitochondria-targeted agent alisporivir on the development of mitochondrial dysfunction in the heart of mice with experimental diabetes mellitus. Alisporivir has been recently identified as a non-immunosuppressive analogue of cyclosporin A, a selective inhibitor of cyclophilin D and the mitochondrial permeability transition pore opening, with a potential in a wide range of therapeutic indications. Our results indicated that alisporivir alleviates diabetes-induced abnormalities in the ultrastructure and functions of mitochondria in cardiomyocytes and increases the rate of glucose utilization in diabetic mice. The data suggest that alisporivir acts as a mitochondria-targeted metabolic reprogramming agent and attenuates oxidative damage to the heart tissue of diabetic mice. Diabetes mellitus is a systemic metabolic disorder associated with mitochondrial dysfunction, with the mitochondrial permeability transition (MPT) pore opening being considered as one of its possible mechanisms. The effect of alisporivir, a non-immunosuppressive cyclosporin derivative and a selective inhibitor of the MPT pore opening, on the ultrastructure and functions of the heart mitochondria of mice with diabetes mellitus induced by a high-fat diet combined with streptozotocin injections was studied. The treatment of diabetic animals with alisporivir (2.5 mg/kg ip for 20 days) increased the rate of glucose clearance during the glucose tolerance test. The blood glucose level and the indicator of heart rate in alisporivir-treated diabetic mice tended to restore. An electron microscopy analysis showed that alisporivir prevented mitochondrial swelling and ultrastructural alterations in cardiomyocytes of diabetic mice. Alisporivir canceled the diabetes-induced increases in the susceptibility of heart mitochondria to the MPT pore opening and the level of lipid peroxidation products, but it did not affect the decline in mitochondrial oxidative phosphorylation capacity. The mRNA expression levels of Pink1 and Parkin in the heart tissue of alisporivir-treated diabetic mice were elevated, suggesting the stimulation of mitophagy. In parallel, alisporivir decreased the level of mtDNA in the heart tissue. These findings suggest that targeting the MPT pore opening by alisporivir alleviates the development of mitochondrial dysfunction in the diabetic heart. The cardioprotective effect of the drug in diabetes can be mediated by the induction of mitophagy and the inhibition of lipid peroxidation in the organelles. [ABSTRACT FROM AUTHOR]

Supporting mitochondrial function is one of the therapeutic strategies that improve the functioning of skeletal muscle in Duchenne muscular dystrophy (DMD). In this work, we studied the effect of a non-immunosuppressive inhibitor of mitochondrial permeability transition pore (MPTP) alisporivir (5 mg/kg/day), reducing the intensity of the necrotic process and inflammation in skeletal muscles on the cardiac phenotype of dystrophin-deficient mdx mice. We found that the heart mitochondria of mdx mice show an increase in the intensity of oxidative phosphorylation and an increase in the resistance of organelles to the MPT pore opening. Alisporivir had no significant effect on the hyperfunctionalization of the heart mitochondria of mdx mice, and the state of the heart mitochondria of wild-type animals did not affect the dynamics of organelles but significantly suppressed mitochondrial biogenesis and reduced the amount of mtDNA in the heart muscle. Moreover, alisporivir suppressed mitochondrial biogenesis in the heart of wild-type mice. Alisporivir treatment resulted in a decrease in heart weight in mdx mice, which was associated with a significant modification of the transmission of excitation in the heart. The latter was also noted in the case of WT mice treated with alisporivir. The paper discusses the prospects for using alisporivir to correct the function of heart mitochondria in DMD. [ABSTRACT FROM AUTHOR]

In Alzheimer's disease (AD), the molecular mechanisms involved in the neurodegeneration are still incompletely defined, though this aspect is crucial for a better understanding of the malady and for devising effective therapies. Mitochondrial dysfunctions and altered Ca2+ signaling have long been implicated in AD, though it is debated whether these events occur early in the course of the pathology, or whether they develop at late stages of the disease and represent consequences of different alterations. Mitochondria are central to many aspects of cellular metabolism providing energy, lipids, reactive oxygen species, signaling molecules for cellular quality control, and actively shaping intracellular Ca2+ signaling, modulating the intensity and duration of the signal itself. Abnormalities in the ability of mitochondria to take up and subsequently release Ca2+ could lead to changes in the metabolism of the organelle, and of the cell as a whole, that eventually result in cell death. We sought to investigate the role of mitochondria and Ca2+ signaling in a model of Familial Alzheimer's disease and found early alterations in mitochondria physiology under stressful condition, namely, reduced maximal respiration, decreased ability to sustain membrane potential, and a slower return to basal matrix Ca2+ levels after a mild excitotoxic stimulus. Treatment with an inhibitor of the permeability transition pore attenuated some of these mitochondrial disfunctions and may represent a promising tool to ameliorate mitochondria and cellular functioning in AD and prevent or slow down cell loss in the disease. [ABSTRACT FROM AUTHOR]