Cyclophilin D knockout significantly prevents HCC development in a streptozotocin-induced mouse model of diabetes-linked NASH.

A family of Peptidyl-prolyl isomerases (PPIases), called Cyclophilins, localize to numerous intracellular and extracellular locations where they contribute to a variety of essential functions. We previously reported that non-immunosuppressive pan-cyclophilin inhibitor drugs like reconfilstat (CRV431) or NV556 decreased multiple aspects of non-alcoholic fatty liver disease (NAFLD) in mice under two different non-alcoholic steatohepatitis (NASH) mouse models. Both CRV431 and NV556 inhibit several cyclophilin isoforms, among which cyclophilin D (CypD) has not been previously investigated in this context. It is unknown whether it is necessary to simultaneously inhibit multiple cyclophilin family members to achieve therapeutic benefits or if loss-of-function of one is sufficient. Furthermore, narrowing down the isoform most responsible for a particular aspect of NAFLD/NASH, such as hepatocellular carcinoma (HCC), would allow for more precise future therapies. Features of human diabetes-linked NAFLD/NASH can be reliably replicated in mice by administering a single high dose of streptozotocin to disrupt pancreatic beta cells, in conjunction with a high sugar, high fat, high cholesterol western diet over the course of 30 weeks. Here we show that while both wild-type (WT) and Ppif-/- CypD KO mice develop multipe severe NASH disease features under this model, the formation of HCC nodules was significantly blunted only in the CypD KO mice. Furthermore, of differentially expressed transcripts in a qPCR panel of select HCC-related genes, nearly all were downregulated in the CypD KO background. Cyclophilin inhibition is a promising and novel avenue of treatment for diet-induced NAFLD/NASH. This study highlights the impact of CypD loss-of-function on the development of HCC, one of the most severe disease outcomes.

Mice lacking cyclophilin B, but not cyclophilin A, are protected from the development of NASH in a diet and chemical-induced model.

Cyclophilins are a diverse family of peptidyl-prolyl isomerases (PPIases) of importance in a variety of essential cellular functions. We previously reported that the pan-cyclophilin inhibitor drug reconfilstat (CRV431) decreased disease in mice under the western-diet and carbon tetrachloride (CCl4) non-alcoholic steatohepatitis (NASH) model. CRV431 inhibits several cyclophilin isoforms, among which cyclophilin A (CypA) and B (CypB) are the most abundant. It is not known whether simultaneous inhibition of multiple cyclophilin family members is necessary for the observed therapeutic effects or if loss-of-function of one is sufficient. Identifying the responsible isoform(s) would enable future fine-tuning of drug treatments. Features of human liver fibrosis and complete NASH can be reliably replicated in mice by administration of intraperitoneal CCl4 alone or CCl4 in conjunction with high sugar, high cholesterol western diet, respectively. Here we show that while wild-type (WT) and Ppia-/- CypA KO mice develop severe NASH disease features under these models, Ppib-/- CypB KO mice do not, as measured by analysis of picrosirius red and hematoxylin & eosin-stained liver sections and TNFα immuno-stained liver sections. Cyclophilin inhibition is a promising and novel avenue of treatment for diet-induced NASH. In this study, mice without CypB, but not mice without CypA, were significantly protected from the development of the characteristic features of NASH. These data suggest that CypB is necessary for NASH disease progression. Further investigation is necessary to determine whether the specific role of CypB in the endoplasmic reticulum secretory pathway is of significance to its effect on NASH development.

Rencofilstat, a cyclophilin inhibitor: A phase 2a, multicenter, single-blind, placebo-controlled study in F2/F3 NASH.

Rencofilstat (RCF) demonstrated antifibrotic effects in preclinical models and was safe and well tolerated in Phase 1 studies. The aim of this Phase 2a study was safety, tolerability, pharmacokinetics, and exploration of efficacy biomarkers in subjects with nonalcoholic steatohepatitis (NASH). This Phase 2a, multicenter, single-blind, placebo-controlled study randomized 49 presumed F2/F3 subjects to RCF 75 mg once daily (QD), RCF 225 mg QD, or placebo for 28 days. Primary safety and tolerability endpoints were explored using descriptive statistics with post hoc analyses comparing active to placebo groups. Pharmacokinetics were evaluated using population pharmacokinetics methods. Efficacy was explored using biomarkers, transcriptomics, and lipidomics. RCF was safe and well tolerated, with no safety signals identified. The most frequently reported treatment-emergent adverse events were constipation, diarrhea, back pain, dizziness, and headache. No clinically significant changes in laboratory parameters were observed, and RCF pharmacokinetics were unchanged in subjects with NASH. Alanine transaminase (ALT) reduction was greater in active subjects than in placebo groups. Nonparametric analysis suggested that ALT reductions were statistically different in the 225-mg cohort compared with matching placebo: -16.3 ± 25.5% versus -0.7 ± 13.4%, respectively. ProC3 and C6M reduction was statistically significant in groups having baseline ProC3 > 15.0 ng/ml. RCF was safe and well tolerated after 28 days in subjects with presumed F2/F3 NASH. Presence of NASH did not alter its pharmacokinetics. Reductions in ALT, ProC3, and C6M suggest direct antifibrotic effects with longer treatment duration. Reductions in key collagen genes support a mechanism of action via suppression and/or regression of collagen deposition. Conclusion: These results support advancement of rencofilstat into a larger and longer Phase 2b study.

Differential Effects of Voclosporin and Tacrolimus on Insulin Secretion From Human Islets.

The incidence of new onset diabetes after transplant (NODAT) has increased over the past decade, likely due to calcineurin inhibitor-based immunosuppressants, including tacrolimus (TAC) and cyclosporin. Voclosporin (VCS), a next-generation calcineurin inhibitor, is reported to cause fewer incidences of NODAT but the reason is unclear. While calcineurin signaling plays important roles in pancreatic ß-cell survival, proliferation, and function, its effects on human ß-cells remain understudied. In particular, we do not understand why some calcineurin inhibitors have more profound effects on the incidence of NODAT. We compared the effects of TAC and VCS on the dynamics of insulin secretory function, programmed cell death rate, and the transcriptomic profile of human islets. We studied 2 clinically relevant doses of TAC (10 ng/mL, 30 ng/mL) and VCS (20 ng/mL, 60 ng/mL), meant to approximate the clinical trough and peak concentrations. TAC, but not VCS, caused a significant impairment of 15 mM glucose-stimulated and 30 mM KCl-stimulated insulin secretion. This points to molecular defects in the distal stages of exocytosis after voltage-gated Ca2+ entry. No significant effects on islet cell survival or total insulin content were identified. RNA sequencing showed that TAC significantly decreased the expression of 17 genes, including direct and indirect regulators of exocytosis (SYT16, TBC1D30, PCK1, SMOC1, SYT5, PDK4, and CREM), whereas VCS has less broad, and milder, effects on gene expression. Clinically relevant doses of TAC, but not VCS, directly inhibit insulin secretion from human islets, likely via transcriptional control of exocytosis machinery.

Cyclophilin inhibition as a potential treatment for nonalcoholic steatohepatitis (NASH).

Introduction: Cyclophilins are a family of diverse regulatory enzymes that have been studied for over 30 years; they participate in many pathophysiological processes. Genetic deletion or pharmacologic inhibition of cyclophilins has shown therapeutic effects in a wide spectrum of disease models, including liver disorders, and hence may be beneficial in treating nonalcoholic steatohepatitis (NASH).Areas Covered: This articles briefly describes cyclophilin isomerases and the main classes of cyclophilin antagonists; it then summarizes data showing cyclophilin participation in the major pathophysiological activities that occur in NASH.Expert Opinion: Optimization of therapeutic outcomes in the treatment of NASH may be best realized by targeting multiple pathologic pathways, especially when treating advanced stages of the disease. A preferred approach for achieving this goal is to use compounds such as cyclophilin inhibitors that simultaneously target multiple disease processes. The pleiotropic benefits of this drug class derive from the extraordinary functionality of prolyl isomerization as a regulatory mechanism and its evolutionary diversification into many biochemical pathways. Nonimmunosuppressive analogs of cyclosporine A are the most thoroughly characterized cyclophilin inhibitors and show significant potential to attenuate several of the major pathophysiological events in NASH - mitochondrial dysfunction, cellular injury and death, inflammation, and in particular, fibrosis.

A Pan-Cyclophilin Inhibitor, CRV431, Decreases Fibrosis and Tumor Development in Chronic Liver Disease Models.

Previous studies show that cyclophilins contribute to many pathologic processes, and cyclophilin inhibitors demonstrate therapeutic activities in many experimental models. However, no drug with cyclophilin inhibition as the primary mode of action has advanced completely through clinical development to market. In this study, we present findings on the cyclophilin inhibitor, CRV431, that highlight its potential as a drug candidate for chronic liver diseases. CRV431 was found to potently inhibit all cyclophilin isoforms tested-A, B, D, and G. Inhibitory constant or IC50 values ranged from 1 to 7 nM, which was up to 13 times more potent than the parent compound, cyclosporine A (CsA), from which CRV431 was derived. Other CRV431 advantages over CsA as a nontransplant drug candidate were significantly diminished immunosuppressive activity, less drug transporter inhibition, and reduced cytotoxicity potential. Oral dosing to mice and rats led to good blood exposures and a 5- to 15-fold accumulation of CRV431 in liver compared with blood concentrations across a wide range of CRV431 dosing levels. Most importantly, CRV431 decreased liver fibrosis in a 6-week carbon tetrachloride model and in a mouse model of nonalcoholic steatohepatitis (NASH). Additionally, CRV431 administration during a late, oncogenic stage of the NASH disease model resulted in a 50% reduction in the number and size of liver tumors. These findings are consistent with CRV431 targeting fibrosis and cancer through multiple, cyclophilin-mediated mechanisms and support the development of CRV431 as a safe and effective drug candidate for liver diseases. SIGNIFICANCE STATEMENT: Cyclophilin inhibitors have demonstrated therapeutic activities in many disease models, but no drug candidates have yet advanced completely through development to market. In this study, CRV431 is shown to potently inhibit multiple cyclophilin isoforms, possess several optimized pharmacological properties, and decrease liver fibrosis and tumors in mouse models of chronic liver disease, which highlights its potential to be the first approved drug primarily targeting cyclophilin isomerases.

Development, Characterization, and Pharmacokinetic Evaluation of a CRV431 Loaded Self-Microemulsifying Drug Delivery System.

PURPOSE: The objective of this study was to develop a self-microemulsifying drug delivery system (SMEDDS) formulation for the oral delivery of CRV431, a non-immunosuppressive analogue of cyclosporine A. Relative to cyclosporine A, CRV431 is poorly soluble in lipid solvents and thusly presents a challenge for the development of a formulation of sufficient oral bioavailability for clinical use. METHODS: The solubility of CRV431, a cyclosporine derivative, was determined in a range of commonly used surfactants, oils and co-solvents. A pseudo-ternary phase diagram was constructed from the most soluble excipients and prototype formulations, SERIES 1 and SERIES 2 were developed. The pharmacokinetics, following single oral doses of 1 and 3 mg/kg of CRV431 SMEDDS, was studied in healthy human volunteers using liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS). RESULTS: The maximum drug load for the SERIES 1 formulations was less than 40 mg/ml. Manipulation of the excipient ratios allowed for the development of SERIES 2 formulations, which had higher drug loading capacity and stability for CRV431 compared to SERIES 1. Further improvements allowed for the development of an optimized SMEDDS formulation containing up to 90 mg/ml CRV431 and which generated a microemulsion mean particle size of 25 nm when dispersed into aqueous media. The pharmacokinetics of the optimized CRV431 SMEDDS displayed excellent total body exposure and dose-proportional effects in humans, and high drug levels in the liver of rats. CONCLUSIONS: The developed SMEDDS formulation should allow for effective clinical development of CRV431, targeted to the treatment of liver diseases including hepatitis B (HBV), fibrosis, and hepatocellular carcinoma.

In Vitro Phase I Metabolism of CRV431, a Novel Oral Drug Candidate for Chronic Hepatitis B.

The cytochrome P450-mediated Phase I in vitro metabolism of CRV431 was studied using selective chemical inhibition and recombinant human enzymes. Additionally, the metabolic profile of CRV431 in human, rat, and monkey liver microsomes was investigated. Liver microsomes were incubated for 0-80 min with CRV431, and the metabolite profile was assessed by electrospray ionization liquid chromatography mass spectrometry (ESI-LCMS). CRV431 was extensively metabolized through oxidation to produce various hydroxylated and demethylated species. Species identified included monohydroxylated CRV431 (two distinct products), dihydroxylated CRV431, demethylated CRV431 (two distinct products), demethylated and hydroxylated CRV431 (two distinct products), didemethylated and hydroxylated CRV431, and didemethylated and dihydroxylated CRV431. The magnitude of metabolism was greatest in monkey, followed by human, followed by rat. Importantly, all of the species identified in human microsomes were correspondingly identified in monkey and/or rat microsomes. Human liver microsome studies using selective chemical inhibition, as well as studies using recombinant human cytochrome P450 enzymes, revealed that the major enzymes involved are cytochromes P450 3A4 and 3A5. Enzymes 1A2, 2B6, 2C8, 2C9, 2C19, and 2D6 are not involved in the in vitro metabolism of CRV431. This information will be useful for the further development of CRV431 both preclinically and clinically.

Neutralization of chemokines RANTES and MIG increases virus antigen expression and spinal cord pathology during Theiler's virus infection.

The role of chemokines during some viral infections is unpredictable because the inflammatory response regulated by these molecules can have two, contrasting effects-viral immunity and immunopathologic injury to host tissues. Using Theiler's virus infection of SJL mice as a model of this type of disease, we have investigated the roles of two chemokines-regulated on activation, normal T cell-expressed and secreted (RANTES) chemokine and monokine induced by IFN-gamma (MIG)-by treating mice with antisera that block lymphocyte migration. Control, infected mice showed virus persistence, mild inflammation and a small degree of demyelination in the white matter of the spinal cord at 6 weeks post-infection. Treatment of mice with RANTES antiserum starting at 2 weeks post-infection increased both viral antigen expression and the severity of inflammatory demyelination at 6 weeks post-infection. MIG antiserum increased the spread of virus and the proportion of spinal cord white matter with demyelination. Overall, viral antigen levels correlated strongly with the extent of pathology. At the RNA level, high virus expression was associated with low IL-2 and high IL-10 levels, and RANTES antiserum decreased the IL-2/IL-10 ratio. Our results suggest that RANTES and MIG participate in an immune response that attempts to restrict viral expression while limiting immunopathology and that anti-chemokine treatment poses the risk of exacerbating both conditions in the long term.

Genetically dominant spinal cord repair in a murine model of chronic progressive multiple sclerosis.

For reasons that are not well understood, central nervous system repair in multiple sclerosis is often minimal. We present evidence, in a murine model of chronic progressive multiple sclerosis, that genetic factors can substantially influence remyelination, axonal integrity, and neurologic function. Four inbred mouse strains, SJL, B10.D1-H2(q), FVB, and SWR, developed extensive inflammatory demyelination by 3 months after infection with Theiler's murine encephalomyelitis virus. Demyelination continued lifelong in SJL and B10.D1-H2(q) mice, accompanied by axonal injury, minimal remyelination, and progressive motor dysfunction. In contrast, FVB and SWR mice showed less axonal injury, progressive remyelination, and stabilization of motor function. Genetic dominance of the reparative traits was demonstrated by crossing remyelinating strains (FVB and SWR) with nonremyelinating strains (SJL and B10.D1-H2(q)). All F1 mice developed a phenotype identical to FVB and SWR, showing extensive remyelination, partial preservation of axons, and preserved motor function. Analyses of viral RNA and antigen, immune cell infiltration, and antiviral antibody titers did not predict the phenotypic differences between strains. These results highlight the significant extent to which hereditary factors can control disease course and demonstrate that the switch from a pathogenic to a reparative phenotype can occur even after prolonged inflammatory demyelination.

Direct comparison of demyelinating disease induced by the Daniel's strain and BeAn strain of Theiler's murine encephalomyelitis virus.

We compared CNS disease following intracerebral injection of SJL mice with Daniel's (DA) and BeAn 8386 (BeAn) strains of Theiler's murine encephalomyelitis virus (TMEV). In tissue culture, DA was more virulent then BeAn. There was a higher incidence of demyelination in the spinal cords of SJL/J mice infected with DA as compared to BeAn. However, the extent of demyelination was similar between virus strains when comparing those mice that developed demyelination. Even though BeAn infection resulted in lower incidence of demyelination in the spinal cord, these mice showed significant brain disease similar to that observed with DA. There was approximately 100 times more virus specific RNA in the CNS of DA infected mice as compared to BeAn infected mice. This was reflected by more virus antigen positive cells (macrophages/microglia and oligodendrocytes) in the spinal cord white matter of DA infected mice as compared to BeAn. There was no difference in the brain infiltrating immune cells of DA or BeAn infected mice. However, BeAn infected mice showed higher titers of TMEV specific antibody. Functional deficits as measured by Rotarod were more severe in DA infected versus BeAn infected mice. These findings indicate that the diseases induced by DA or BeAn are distinct.

Naturally occurring human IgM antibody that binds B7-DC and potentiates T cell stimulation by dendritic cells.

A human IgM Ab, serum-derived human IgM 12 (sHIgM12), is identified that binds mouse and human dendritic cells (DC), inducing dramatic immunopotentiation following treatment of the mouse DC in vitro. Competition, transfection, and knockout studies identified the ligand on mouse DC as the costimulatory molecule family member B7-DC. Potent T cell responses are stimulated by Ag-pulsed DC treated with the sHIgM12 Ab in vitro and upon adoptive transfer of Ab-treated Ag-pulsed DC into animals. The multivalent structure of pentameric IgM provides the potential for cross-linking cell surface targets, endowing the soluble Abs with biological potential not normally associated with immune function. The ability of the sHIgM12 Ab to potentiate the immune response is dependent on the multimeric structure of IgM, as bivalent monomers do not retain this property. Furthermore, pretreatment of DC with IgM monomers blocks subsequent potentiation by intact IgM pentamers, an indication that cross-linking of B7-DC on the cell surface is critical for potentiation of Ag presentation. These findings imply that, in addition to known costimulatory roles, B7-DC can function as a receptor for signals delivered by cells expressing B7-DC ligands.

Polyreactive antibodies to glatiramer acetate promote myelin repair in murine model of demyelinating disease.

Using a murine model of demyelinating disease, we demonstrate that remyelination of spinal cord axons is promoted by antibodies to glatiramer acetate (GA, Copolymer-1, Copaxone), a therapeutic agent for multiple sclerosis (MS). Glatiramer acetate is a mixture of randomly synthesized peptides that induces both T cell activation and antibody production in all treated individuals. These observations prompted us to compare the independent effects of adoptively transferred GA-reactive T cells and antibodies in mice with chronic inflammatory demyelination induced by Theiler's virus. Transferred T cells had no effect on lesion load or the extent of remyelination. Purified polyclonal GA antibodies also did not alter lesion load, which suggests that neither GA T cells or antibodies were pathogenic. On the contrary, GA antibodies enhanced the normally low level of remyelination in chronic lesions. The antibodies, which were primarily immunoglobulin (Ig) G1 and IgG2, cross-reacted with oligodendrocytes, perivascular infiltrating cells, astrocytes, and neurons in spinal cord sections. In glial cultures they bound subsets of early lineage oligodendrocytes and microglia. Thus, several mechanisms may have contributed to the promotion of remyelination. These results support the hypothesis that the antibody response in GA-treated patients is beneficial by facilitating repair of demyelinated lesions.