A Randomized, Controlled Phase I/II Study to Evaluate the Safety and Efficacy of MGV354 for Ocular Hypertension or Glaucoma.

PURPOSE: To assess the clinical safety, tolerability, and efficacy of topically administered MGV354, a soluble guanylate cyclase (sGC) activator, in patients with ocular hypertension (OH) or glaucoma. DESIGN: Double-masked, randomized, and vehicle-controlled study. METHODS: Parts 1 and 2 evaluated safety and tolerability to identify the maximum tolerated dose (MTD) of once-daily MGV354 in 32 healthy volunteers (Part 1) and 16 patients with OH or glaucoma (Part 2) at a single clinical site. Part 3 was a multisite trial that evaluated intraocular pressure (IOP)-lowering efficacy of the MTD administered nightly for 1 week in 50 patients with minimum IOP of 24 mm Hg at 8 AM, with a main outcome measure of mean diurnal IOP at day 8 compared to baseline (ClinicalTrials.govNCT02743780). RESULTS: There was no difference in favor of MGV354 for IOP lowering; change from baseline to day 8 in mean diurnal IOP was -0.6 mm Hg for MGV354-treated patients and -1.1 mm Hg for vehicle-treated patients in Part 3, with a confidence interval of -0.7 to 1.7. The most common adverse events reported after MGV354 administration were conjunctival and ocular hyperemia. CONCLUSIONS: Overall, MGV354 0.1% demonstrated no statistically significant effect compared to vehicle in lowering IOP based on the study's main outcome measure. MGV354 produced ocular hyperemia consistent with its pharmacology.

A Novel Selective Soluble Guanylate Cyclase Activator, MGV354, Lowers Intraocular Pressure in Preclinical Models, Following Topical Ocular Dosing.

Purpose: The nitric oxide/soluble guanylate cyclase/protein kinase G (NO/sGC/PKG) is known to be involved in the regulation of intraocular pressure (IOP) and may be dysregulated in glaucoma. The purpose is to demonstrate that the sGC activator MGV354 lowers IOP in a monkey model of glaucoma and could be considered as a possible new clinical drug candidate. Methods: Changes to cGMP were assessed in primary human trabecular meshwork (hNTM) cells and binding studies were conducted using human sGC full-length protein. Ocular safety tolerability, exposure, and efficacy studies were conducted in rabbit and monkey models following topical ocular dosing of MGV354. Results: sGC was highly expressed in the human and cynomolgus monkey outflow pathways. MGV354 had a 7-fold greater Bmax to oxidized sGC compared to that of reduced sGC and generated an 8- to 10-fold greater cGMP compared to that of a reduced condition in hTM cells. A single topical ocular dose with MGV354 caused a significant dose-dependent reduction of 20% to 40% (versus vehicle), lasting up to 6 hours in pigmented rabbits and 24 hours postdose in a cynomolgus monkey model of glaucoma. The MGV354-induced IOP lowering was sustained up to 7 days following once-daily dosing in a monkey model of glaucoma and was greater in magnitude compared to Travatan (travoprost)-induced IOP reduction. Mild to moderate ocular hyperemia was the main adverse effect noted. Conclusions: MGV354 represents a novel class of sGC activators that can lower IOP in preclinical models of glaucoma. The potential for sGC activators to be used as effective IOP-lowering drugs in glaucoma patients could be further determined in clinical studies.

Discovery of Highly Potent and Selective Small-Molecule Reversible Factor D Inhibitors Demonstrating Alternative Complement Pathway Inhibition in Vivo.

The highly specific S1 serine protease factor D (FD) plays a central role in the amplification of the complement alternative pathway (AP) of the innate immune system. Genetic associations in humans have implicated AP activation in age-related macular degeneration (AMD), and AP dysfunction predisposes individuals to disorders such as paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS). The combination of structure-based hit identification and subsequent optimization of the center (S)-proline-based lead 7 has led to the discovery of noncovalent reversible and selective human factor D (FD) inhibitors with drug-like properties. The orally bioavailable compound 2 exerted excellent potency in 50% human whole blood in vitro and blocked AP activity ex vivo after oral administration to monkeys as demonstrated by inhibition of membrane attack complex (MAC) formation. Inhibitor 2 demonstrated sustained oral and ocular efficacy in a model of lipopolysaccharide (LPS)-induced systemic AP activation in mice expressing human FD.

Inflammation and immunogenicity limit the utility of the rabbit as a nonclinical species for ocular biologic therapeutics.

The nonclinical safety evaluation of therapeutic drug candidates is commonly conducted in two species (rodent and non-rodent) in keeping with international health authority guidance. Biologic drugs typically have restricted species cross-reactivity, necessitating the evaluation of safety in non-human primates and thus limiting the utility of lower order species. Safety studies of cross-reactive ocular biologic drug candidates have been conducted in rabbits as a second toxicology species, despite the fact that rabbits are not a rodent species. Such studies are often confounded by the development of anti-drug antibodies and severe ocular inflammation, the latter requiring studies to be terminated prematurely for animal welfare reasons. Notably, these confounding factors preclude the interpretation of safety. Nonclinical toxicology programs should be designed with consideration of ethical animal use and 3Rs principles (Replacement, Reduction and Refinement). The experience of several pharmaceutical sponsors, demonstrating that toxicology studies of ocular (intravitreal and topical ocular) biologic drug candidates in the rabbit are of limited interpretive value, calls into question the utility of such studies in this species and indicates that such studies should not be conducted.

Okadaic acid and trifluoperazine enhance Agrobacterium-mediated transformation in eastern white pine.

Mature zygotic embryos of recalcitrant Christmas tree species eastern white pine (Pinus strobus L.) were used as explants for Agrobacterium tumefaciens strain GV3101-mediated transformation using the uidA (beta-Glucuronidase) gene as a reporter. Influence of the time of sonication and the concentrations of protein phosphatase inhibitor (okadaic acid) and kinase inhibitor (trifluoperazine) on Agrobacterium-mediated transformation have been evaluated. A high transformation frequency was obtained after embryos were sonicated for 45-50 s, or treated with 1.5-2.0 microM okadaic acid or treated with 100-200 microM trifluoperazine, respectively. Protein phosphatase and kinase inhibitors enhance Agrobacterium-mediated transformation in eastern white pine. A 2-3.5-fold higher rate of hygromycin-resistant callus was obtained with an addition of 2 microM okadaic acid or 150 microM trifluoperazine or sonicated embryos for 45 s. Stable integration of the uidA gene in the plant genome of eastern white pine was confirmed by polymerase chain reaction (PCR), Southern and northern blot analyses. These results demonstrated that a stable and enhanced transformation system has been established in eastern white pine and this system would provide an opportunity to transfer economically important genes into this Christmas tree species.

Genetic transformation and gene silencing mediated by multiple copies of a transgene in eastern white pine.

An efficient transgenic eastern white pine (Pinus strobus L.) plant regeneration system has been established using Agrobacterium tumefaciens strain GV3850-mediated transformation and the green fluorescent protein (gfp) gene as a reporter in this investigation. Stable integration of transgenes in the plant genome of pine was confirmed by polymerase chain reaction (PCR), Southern blot, and northern blot analyses. Transgene expression was analysed in pine T-DNA transformants carrying different numbers of copies of T-DNA insertions. Post-transcriptional gene silencing (PTGS) was mostly obtained in transgenic lines with more than three copies of T-DNA, but not in transgenic lines with one copy of T-DNA. In situ hybridization chromosome analysis of transgenic lines demonstrated that silenced transgenic lines had two or more T-DNA insertions in the same chromosome. These results suggest that two or more T-DNA insertions in the same chromosome facilitate efficient gene silencing in transgenic pine cells expressing green fluorescent protein. There were no differences in shoot differentiation and development between transgenic lines with multiple T-DNA copies and transgenic lines with one or two T-DNA copies.

Expression of a transcription factor from Capsicum annuum in pine calli counteracts the inhibitory effects of salt stress on adventitious shoot formation.

Transcription factors regulating the stress-responsive gene expression play an important role in plant stress adaptation. In this study, we examined the salt stress tolerance of transgenic Virginia pine (Pinus virginiana Mill.) overexpressing a Capsicum annuum ERF/AP2-type transcription factor (CaPF1), which may enhance the ability of transgenic plants to tolerate various kinds of stresses during vegetative growth. CaPF1 transgene increased the salt and oxidative stress tolerances of pine tissues and counteracted the inhibitory effects of salt stress on the growth of transgenic Virginia pine calli, shoots, and plants. To our surprise, the ability of shoot formation was enhanced in three CaPF1 transgenic Virginia pine cell lines under stress of different NaCl concentrations. NaCl at 200 mM significantly increased the frequency of adventitious shoot formation and the number of shoots per gram calli. Measurement of plant hormone demonstrated that the levels of cytokinin was altered in CaPF1-overexpressed Virginia pine calli, compared to the control. Based on our results, we speculate that the altered level of cytokinin may result in enhancing adventitious shoot formation of transgenic calli exposed to salt for 1 week via an unknown mechanism.

Plant regeneration through multiple adventitious shoot differentiation from callus cultures of slash pine (Pinus elliottii).

A plant regeneration system through multiple adventitious shoot differentiation from callus cultures has been established in slash pine (Pinus elliottii). Influences of seven different basal media on callus induction, adventitious shoot formation, and rooting were investigated. Among the different basal media, B5, SH, and TE proved to be suitable for callus induction and plantlet regeneration. Multiple adventitious shoot formation was obtained from callus cultures of slash pine on B5, SH, and TE media containing indole-3-butyric acid, N6-benzyladenine, and thidiazuron. Scanning electron microscopy demonstrated the early development of adventitious shoots derived from callus cultures. These results indicate that an efficient plant regeneration protocol for micropropagation of slash pine had been established. This protocol could be most useful for future studies on genetic transformation of slash pine.

Mevalonate kinase activity during different stages of plant regeneration from nodular callus cultures in white pine (Pinus strobus).

Mevalonate kinase (MK) catalyzes a step in the isoprenoid biosynthetic pathway, which leads to a huge number of compounds that play important roles in plant growth and development. Here, we report on changes in MK activity in white pine (Pinus strobus L.) during plant regeneration by adventitious shoot organogenesis from cotyledons of mature embryos, including nodular callus induction, shoot formation and rooting. Nodular calli were induced from Pinus strobus (PS) embryos by culture in nodular callus induction medium in a 0-, 8- or 16-h photoperiod. Mevalonate kinase activity peaked in nodular calli after three weeks of culture on nodular callus induction medium in a 16-h photoperiod, whereas frequency of nodular callus formation peaked after 4 weeks of culture on nodular callus induction medium in darkness. During adventitious shoot formation, MK activity peaked in shoots derived from dark-grown nodular calli after 3 weeks on bud formation medium, and frequency of shoot formation was highest in dark-grown nodular calli cultured on bud formation medium for 4 weeks. During rooting, MK activity peaked 2 weeks after transfer of adventitious shoots to rooting medium and rooting frequency was highest in adventitious shoots after 3 weeks on rooting medium. Although during nodular callus induction in darkness MK activity was inversely related to frequency of nodular callus formation, MK activity was highly correlated with frequency of shoot formation and with rooting frequency. The observed increase in MK activity preceding rooting suggests that MK could serve as a marker for rooting of white pine shoots in vitro.

Differential gene silencing induced by short interfering RNA in cultured pine cells associates with the cell cycle phase.

The double-stranded short interfering RNA (siRNA) molecules can silence targeted genes through sequence-specific cleavage of the cognate RNA transcript. The rapid adoption of technologies based on this siRNA interference mechanism has been a widely used method to analyze gene function in plants, invertebrates, and mammalian systems. In order to understand the dynamics of siRNA-mediated gene inactivation during cell division, we have investigated the relationship between the cell cycle phase and the post-transcriptional gene silencing mediated by siRNA in gfp transgenic Virginia pine (Pinus virginiana Mill.) cells. Among the different phases of the cell cycle, transgenic cells at the M phase gave 2-3 times lower gfp silencing than those at the G1, S, and G2 phases. The similar results of the siRNA-mediated gfp silencing were obtained in three transgenic cell lines. Differential gfp silencing induced by siRNA has been confirmed by northern blot, laser scanning microscopy, and siRNA analysis. These data suggested that siRNA-mediated gene inactivation is associated with the cell cycle phase in Virginia pine.

Efficient delivery of small interfering RNA to plant cells by a nanosecond pulsed laser-induced stress wave for posttranscriptional gene silencing.

Small interfering RNA (siRNA) induced posttranscriptional gene silencing (PTGS) has been an efficient method for genetic and molecular analysis of certain developmental and physiological processes and represented a potential strategy for both controlling virus replication and developing therapeutic products. However, there are limitations for the methods currently used to deliver siRNA into cells. We report here, to our knowledge, the first efficient delivery of siRNA to plant cells by a nanosecond pulsed laser-induced stress wave (LISW) for posttranscriptional gene silencing. Using LISW, we are able to silence gene expression in cell cultures of three different plant species rice (Oryza sativa L.), cotton (Gossypium hirsutum L.), and slash pine (Pinus elliottii Engelm.). Gene silencing induced by siRNA has been confirmed by northern blot, laser scanning microscopy, and siRNA analysis. These data suggested that LISW-mediated siRNA delivery can be a reliable and effective method for inducing PTGS in cultured cells.

Overexpression of the pepper transcription factor CaPF1 in transgenic Virginia pine (Pinus Virginiana Mill.) confers multiple stress tolerance and enhances organ growth.

Transcription factors play an important role in regulating gene expression in response to stress and pathogen tolerance. We describe here that overexpression of an ERF/AP2 pepper transcription factor (CaPF1) in transgenic Virginia pine (Pinus virginiana Mill.) confers tolerance to heavy metals Cadmium, Copper, and Zinc, to heat, and to pathogens Bacillus thuringiensis and Staphylococcus epidermidis, as by the survival rate of transgenic plants and the number of decreasing pathogen cells in transgenic tissues. Measurement of antioxidant enzymes ascorbate peroxidase (APOX), glutathione reductase (GR), and superoxide dismutase (SOD) activities demonstrated that the level of the enzyme activities was higher in transgenic Virginia pine plants overexpressing the CaPF1 gene, which may protect cells from the oxidative damage caused by stresses, compared to the controls. Constitutive overexpression of CaPF1 gene enhanced organ growth by increasing organ size and cell numbers in transgenic Virginia pine plants over those in control plants.

Polyamines promote root elongation and growth by increasing root cell division in regenerated Virginia pine (Pinus virginiana Mill.) plantlets.

Polyamines have been demonstrated to play an important role in adventitious root formation and development in plants. Here, we present a detailed analysis of influence of exogenously added polyamines on adventitious root development and its relationship to cold tolerance in Virginia pine (Pinus virginia Mill.). Our results demonstrated that polyamines putrescine (Put), spermidine (Spd), and spermine (Spm) at 0.001 mM improve rooting frequency and promote root elongation. Put, Spd, and Spm at 0.01-1 mM decrease rooting frequency and reduce root elongation root elongation. Measurements of diamine oxidase (DAO, EC 1.4.3.6) and polyamine oxidase (PAO, EC 1.4.3.4) activities showed that higher DAO and PAO enzyme activities were obtained when high concentrations of polyamines were applied and when plantlets were treated for 5-7 week at 4 degrees C and 16 degrees C. Survival rate of plantlets increased with the treatment of polyamines at low temperature. Polyamines increased mitotic index of cells in root tips of regenerated plantlet cultured on medium containing 0.001 microM Put, Spd, or Spm, but did not increase mitotic index in tissues of needle tips of the same plantlets. These results demonstrated that polyamines promote root elongation and growth by increasing root cell division in regenerated Virginia pine plantlets.

High efficiency inducible gene expression system based on activation of a chimeric transcription factor in transgenic pine.

Inducible gene expression systems are needed in functional genomics of tree species. A glucocorticoid-inducible gene expression system was established in a gymnosperm species Virginia pine (Pinus virginiana Mill.) through Agrobacterium tumefaciens-mediated genetic transformation. The results demonstrate that expression of the m-gfp5-ER reporter gene was tightly controlled and 0.1 microM of the glucocorticoid hormone triamcinolone was able to induce m-gfp5-ER expression in transgenic cells. Differential expression of gfp in transgenic cells induced by different concentrations of triamcinolone was observed and confirmed by Northern Blot analysis and by quantitative green fluorescence analyses with Laser Scanning Microscopy. In transgenic plantlets, triamcinolone was taken up efficiently by roots. Triamcinolone was able to induce m-gfp5-ER activity throughout the whole plant. The phenotype of transgenic plantlets was not affected 6 weeks after treatment with 0.1-10 microM triamcinolone. However, 6-week inductions with 100 microM triamcinolone caused growth retardation and developmental defects, as well as inhibition of root formation and elongation. With careful selection of transgenic lines, the inducible gene expression presented in this study could be a very valuable alternative for functional identification of novel genes in plants, especially in pine.

Peroxidase and catalase activities are involved in direct adventitious shoot formation induced by thidiazuron in eastern white pine (Pinus strobus L.) zygotic embryos.

We reported establishment of an efficient plant regeneration procedure through direct adventitious shoot (DAS) formation from cotyledons and hypocotyls of eastern white pine (Pinus strobus L.) mature embryos in this investigation. Multiple DASs were initiated from cotyledons of embryos on PS medium containing N6-benzyladenine (BA), thidiazuron (TDZ), or kinetin (KIN). Among different concentrations of casein enzymatic hydrosylate (CH) and glutamine used in this study, 500 mg l(-1) CH or 600 mg l(-1) glutamine induced the highest frequency of DAS formation. Rooting of regenerated shoots was obtained on PS medium supplemented with 0.01-0.1 microM indole-3-acetic acid (IAA) with the highest frequency on medium containing 0.01 muM IAA. No DASs were obtained on medium without TDZ. Measurement of peroxidase (POD) and catalase (CAT) activity during direct shoot induction and differentiation demonstrated that the lowest POD activity appeared in the 5-6th week of culture and lowest CAT activity occurred in the 7-8th week of culture on medium with TDZ. No such a change in POD and CAT activities was observed on medium without TDZ. These results demonstrated that POD and CAT activities were involved in DAS formation induced by TDZ in eastern white pine.

Relationships between genomic, cell cycle, and mutagenic responses of TK6 cells exposed to DNA damaging chemicals.

Genotoxic stress causes a variety of cellular and molecular responses in mammalian cells, including cell cycle arrest, DNA repair, and apoptosis. These responses result from the interplay between the genotoxic events themselves, and the biological context in which they occur. To better understand this interplay, we investigated cytotoxicty, mutagenesis, cell cycle profile, and global gene expression in the human TK6 lymphoblastoid cell line exposed to six genotoxicants. The six compounds have broad structural diversity and cause genotoxic stress by many different mechanisms, including covalent modification (methyl methanesulfonate, mitomycin C), reactive oxygen species (hydrogen peroxide, bleomycin), and topoisomerase II inhibition (etoposide and doxorubicin). Cell cycle analysis was performed 4 and 20 h following a 4 h chemical exposure. Cells exposed to all compounds experienced S-phase arrest at the 8h time point, but by 24 h had markedly different cell cycle responses. Cells exposed to compounds that cause covalent modification had a strong G2/M arrest at 24 h. These cells also had a robust (>25-fold) increase in mutant frequency, and had a moderate but sustained p53 response at 4, 8, and 24h, detectable as approximately 2-5-fold increases in transcript levels for p21WAF1/CIP1, GADD45alpha, BTG2, and cyclin G1. In contrast, cells exposed to the reactive oxygen compounds had little or no G2/M arrest at 24 h and no increase in mutant frequency. In addition, these compounds caused a strong but transient induction of the p53 pathway, detectable as 15-25-fold increases in p21WAF1/CIP1 transcription at 4 h that decreased dramatically by 8h and was near control levels at 24 h. Thus, the mutagenic effect of compounds was consistent with G2/M arrest and sustained kinetics of p53 pathway activation. Global gene expression data were also consistent with the mutagenesis data. Activation of genes associated with cell cycle arrest, the p53 and TNF-related pathways, and chemokines and chemokine receptors, were particularly evident for the reactive oxygen compounds. In contrast, the most mutagenic compounds caused fewer and less robust changes in global gene expression. There was therefore an inverse relationship between global gene expression and mutagenic potency.

Administration of a PPARalpha agonist increases serum apolipoprotein A-V levels and the apolipoprotein A-V/apolipoprotein C-III ratio.

Apolipoprotein A-V (apoA-V) first gained attention as a regulator of triglycerides through transgenic mouse studies. Furthermore, peroxisome proliferator-activated receptor alpha (PPARalpha) agonists such as fenofibrate increase apoA-V mRNA expression. Our group recently developed the first assay to quantitate serum apoA-V levels. Therefore, we sought to determine whether administration of a PPARalpha agonist would increase circulating apoA-V. Cynomolgus monkeys were dosed for 14 days with 0.3 mg/kg/day LY570977 L-lysine, a potent and selective PPARalpha agonist. Blood samples were drawn throughout the treatment period and after a 2 week washout. Administration of the PPARalpha agonist caused a 50% decrease in triglycerides that reversed at washout. Serum apoA-V concentrations increased 2-fold, correlated inversely with triglycerides, and were reversible at washout. The apoA-V/apoC-III ratio increased >2-fold, with this increase also reversible at washout. These data demonstrate for the first time that a PPARalpha agonist increases circulating apoA-V protein levels and the apoA-V/apoC-III ratio.

Inducible antisense-mediated post-transcriptional gene silencing in transgenic pine cells using green fluorescent protein as a visual marker.

An inducible post-transcriptional gene silencing (PTGS) system was established in Virginia pine (Pinus virginiana Mill.) cells. This system is based on the activation of an antisense gfp gene construct by a chimeric transcriptional activator GVG (Gal4-binding domain-VP16 activation domain-glucocorticoid receptor fusion) upon application of the inducer to gfp transgenic cell lines. A detailed characterization of the inducible PTGS system in transgenic cell lines demonstrated that this system is stringently controlled. The degree of silencing with this construct could be regulated by the concentration of inducer and the time of treatment. Such transgenic cell lines may provide a useful system to study signaling mechanisms of gene silencing in transgenic pine cells. The inducible system could be a useful tool for functional discovery of novel plant genes.

Enhanced tolerance to salt stress in transgenic loblolly pine simultaneously expressing two genes encoding mannitol-1-phosphate dehydrogenase and glucitol-6-phosphate dehydrogenase.

A reproducible approach to improve salt tolerance of conifers has been established by using the technology of plant genetic transformation and using loblolly pine (Pinus taeda L.) as a model plant. Mature zygotic embryos of three genotypes of loblolly pine were infected with Agrobacterium tumefaciens strain LBA 4404 harboring the plasmid pBIGM which carrying two bacterial genes encoding the mannitol-1-phosphate dehydrogenase (Mt1D, EC 1.1.1.17) and glucitol-6-phosphate dehydrogenase (GutD) (EC 1.1.1.140), respectively. Transgenic plantlets were produced on selection medium containing 15 mg l(-1) kanamycin and confirmed by polymerase chain reaction (PCR) and Southern blot analysis of genomic DNA. The Mt1D and GutD genes were expressed and translated into functional enzymes that resulted in the synthesis and accumulation of mannitol and glucitol in transgenic plants. Salt tolerance assays demonstrated that transgenic plantlets producing mannitol and glucitol had an increased ability to tolerate high salinity. These results suggested that an efficient A. tumefaciens-mediated transformation protocol for stable integration of bacterial Mt1D and GutD genes into loblolly pine has been developed and this could be useful for the future studies on engineering breeding of conifers.