NoPv1: a synthetic antimicrobial peptide aptamer targeting the causal agents of grapevine downy mildew and potato late blight.

Grapevine (Vitis vinifera L.) is a crop of major economic importance. However, grapevine yield is guaranteed by the massive use of pesticides to counteract pathogen infections. Under temperate-humid climate conditions, downy mildew is a primary threat for viticulture. Downy mildew is caused by the biotrophic oomycete Plasmopara viticola Berl. & de Toni, which can attack grapevine green tissues. In lack of treatments and with favourable weather conditions, downy mildew can devastate up to 75% of grape cultivation in one season and weaken newly born shoots, causing serious economic losses. Nevertheless, the repeated and massive use of some fungicides can lead to environmental pollution, negative impact on non-targeted organisms, development of resistance, residual toxicity and can foster human health concerns. In this manuscript, we provide an innovative approach to obtain specific pathogen protection for plants. By using the yeast two-hybrid approach and the P. viticola cellulose synthase 2 (PvCesA2), as target enzyme, we screened a combinatorial 8 amino acid peptide library with the aim to identify interacting peptides, potentially able to inhibit PvCesa2. Here, we demonstrate that the NoPv1 peptide aptamer prevents P. viticola germ tube formation and grapevine leaf infection without affecting the growth of non-target organisms and without being toxic for human cells. Furthermore, NoPv1 is also able to counteract Phytophthora infestans growth, the causal agent of late blight in potato and tomato, possibly as a consequence of the high amino acid sequence similarity between P. viticola and P. infestans cellulose synthase enzymes.

Substrate reduction therapy with Miglustat in pediatric patients with GM1 type 2 gangliosidosis delays neurological involvement: A multicenter experience.

BACKGROUND: In GM1 gangliosidosis the lack of function of ß-galactosidase results in an accumulation of GM1 ganglioside and related glycoconjugates in visceral organs, and particularly in the central nervous system, leading to severe disability and premature death. In the type 2 form of the disease, early intervention would be important to avoid precocious complications. To date, there are no effective therapeutic options in preventing progressive neurological deterioration. Substrate reduction therapy with Miglustat, a N-alkylated sugar that inhibits the enzyme glucosylceramide synthase, has been proposed for the treatment of several lysosomal storage disorders such as Gaucher type 1 and Niemann Pick Type C diseases. However, data on Miglustat therapy in patients with GM1 gangliosidosis are still scarce. METHODS: We report here the results of Miglustat administration in four Italian children (average age: 55 months, range 20-125) affected by GM1 gangliosidosis type 2 treated in three different Italian pediatric hospitals specialized in metabolic diseases. CONCLUSION: This treatment was safe and relatively well tolerated by all patients, with stabilization and/or slowing down of the neurological progression in three subjects.

Impact of the organic cation transporter 2 inhibitor cimetidine on the single-dose pharmacokinetics of the glucosylceramide synthase inhibitor lucerastat in healthy subjects.

PURPOSE: Lucerastat is an orally available glucosylceramide synthase inhibitor with a potential to provide substrate reduction therapy for Fabry patients independent of their α-galactosidase A genotype. In humans, lucerastat is mainly eliminated as unchanged parent compound through renal excretion both by active secretion and passive filtration. In vitro studies indicated that lucerastat is a substrate of human organic cation transporter 2 (OCT2) mainly expressed in the kidney. METHODS: Therefore, this clinical study, conducted in 14 healthy male subjects, investigated the effect of 800 mg twice-daily oral administration of the OCT2 inhibitor cimetidine at steady state on the single-dose pharmacokinetics (PK) of 500 mg lucerastat. The safety and tolerability of lucerastat administered alone and concomitantly with cimetidine were also evaluated. RESULTS: Exposure to lucerastat was slightly higher upon co-administration of cimetidine indicated by geometric mean area under the plasma concentration-time curve from zero to infinity (AUC0-∞) ratio of 1.22 (90% confidence interval [CI] 1.16-1.28). Cimetidine delayed the time to reach maximum lucerastat concentrations (tmax) by 1 h but did not affect its elimination half-life (t½) or maximum plasma concentration (Cmax) as geometric mean ratios were 1.00 (0.91-1.10) and 1.04 (0.92-1.17), respectively, at cimetidine steady state. Lucerastat was safe and well tolerated when given alone and in combination with cimetidine. CONCLUSION: These results indicate that the single-dose PK of lucerastat are not changed to a clinically relevant extent by cimetidine-mediated OCT2 inhibition, allowing the concomitant use of OCT2 inhibitors with lucerastat without any need for dose adjustment. TRIAL REGISTRATION: EudraCT: 2017-003725-14; ClinicalTrials.gov: NCT03380455.

A chemical genetic screen reveals that iminosugar inhibitors of plant glucosylceramide synthase inhibit root growth in Arabidopsis and cereals.

Iminosugars are carbohydrate mimics that are useful as molecular probes to dissect metabolism in plants. To analyse the effects of iminosugar derivatives on germination and seedling growth, we screened a library of 390 N-substituted iminosugar analogues against Arabidopsis and the small cereal Eragrostis tef (Tef). The most potent compound identified in both systems, N-5-(adamantane-1-yl-ethoxy)pentyl- L-ido-deoxynojirimycin (L-ido-AEP-DNJ), inhibited root growth in agar plate assays by 92% and 96% in Arabidopsis and Tef respectively, at 10 µM concentration. Phenocopying the effect of L-ido-AEP-DNJ with the commercial inhibitor (PDMP) implicated glucosylceramide synthase as the target responsible for root growth inhibition. L-ido-AEP-DNJ was twenty-fold more potent than PDMP. Liquid chromatography-mass spectrometry (LC-MS) analysis of ceramide:glucosylceramide ratios in inhibitor-treated Arabidopsis seedlings showed a decrease in the relative quantity of the latter, confirming that glucosylceramide synthesis is perturbed in inhibitor-treated plants. Bioinformatic analysis of glucosylceramide synthase indicates gene conservation across higher plants. Previous T-DNA insertional inactivation of glucosylceramide synthase in Arabidopsis caused seedling lethality, indicating a role in growth and development. The compounds identified herein represent chemical alternatives that can overcome issues caused by genetic intervention. These inhibitors offer the potential to dissect the roles of glucosylceramides in polyploid crop species.

A lemon myrtle extract inhibits glucosyltransferases activity of Streptococcus mutans.

Streptococcus mutans is a bacterium found in human oral biofilms (dental plaques) that is associated with the development of dental caries. Glucosyltransferases (GTFs) are key enzymes involved in dental plaque formation, and compounds that inhibit their activities may prevent dental caries. We developed a screening system for GTF-inhibitory activities, and used it to profile 44 types of herbal tea extracts. Lemon myrtle (Backhousia citriodora) extract exhibited the highest GTF-inhibitory activity, with an IC50 for GTF in solution of 0.14 mg mL-1. Furthermore, lemon myrtle extracts had the third-highest polyphenol content of all tested extracts, and strongly inhibited S. mutans biofilm. Interestingly, lemon myrtle extracts did not inhibit cell growth.

Evaluation of the Antifungal Activity of the Novel Oral Glucan Synthase Inhibitor SCY-078, Singly and in Combination, for the Treatment of Invasive Aspergillosis.

Invasive aspergillosis remains a major cause of death among the immunocompromised population and those receiving long-term immunosuppressive therapy. In light of increased azole resistance, variable outcomes with existing echinocandin monotherapy and combination therapy, and persistent high mortality rates, new antifungal agents for the treatment of invasive aspergillosis are clearly needed. SCY-078 is the first-in-class triterpenoid antifungal, a novel class of glucan synthase inhibitors with broad in vitro and in vivo activity against a broad spectrum of Candida and Aspergillus species. In vitro testing of clinical strains of Aspergillus fumigatus and non-fumigatus Aspergillus strains showed that SCY-078 had potent fungistatic activity (minimum effective concentration for 90% of strains tested = 0.125 µg/ml) compared with the activities of amphotericin B (MIC90 = 8 µg/ml) and voriconazole (MIC90 = 2 µg/ml). Testing of SCY-078 in combination with isavuconazole or voriconazole demonstrated synergistic activity against the majority of the azole-susceptible strains tested, and SCY-078 in combination with amphotericin B was synergistic against the azole-susceptible strains, as well as one known resistant cyp51A mutant. SCY-078 may be an important additional antifungal for first-line or salvage monotherapy or combination treatment of invasive aspergillosis.

Micafungin Enhances the Human Macrophage Response to Candida albicans through ß-Glucan Exposure.

Micafungin belongs to the antifungal family of echinocandins, which act as noncompetitive inhibitors of the fungal cell wall ß-1,3-d-glucan synthase. Since Candida albicans is the most prevalent pathogenic fungus in humans, we study the involvement of micafungin in the modulation of the inflammatory response developed by human tissue macrophages against C. albicans The MIC for micafungin was 0.016 µg/ml on the C. albicans SC5314 standard strain. Micafungin induced a drastic reduction in the number of exponential SC5314 viable cells, with the fungicidal effect being dependent on the cellular metabolic activity. Notably, micafungin also caused a structural remodelling of the cell wall, leading to exposure of the ß-glucan and chitin content on the external surface. At the higher doses used (0.05 µg/ml), the antifungal also induced the blowing up of budding yeasts. In addition, preincubation with micafungin before exposure to human tissue macrophages enhanced the secretion of tumor necrosis factor alpha (TNF-α), interleukin-17A (IL-17A), and IL-10 cytokines. Our results strongly suggest that in C. albicans treatment with micafungin, in addition to having the expected toxic antifungal effect, it potentiates the immune response, improving the interaction and activation of human macrophages, probably through the unmasking of ß-glucans on the cell wall surface.

Lucerastat, an Iminosugar for Substrate Reduction Therapy: Tolerability, Pharmacodynamics, and Pharmacokinetics in Patients With Fabry Disease on Enzyme Replacement.

Lucerastat is a glucosylceramide synthase inhibitor aimed at reducing production of glycosphingolipids (GSLs), including those accumulating in Fabry disease. The safety, tolerability, pharmacodynamics, and pharmacokinetics of oral lucerastat were evaluated in an exploratory study in patients with Fabry disease. In this single-center, open-label, randomized study, 10 patients received lucerastat 1,000 mg b.i.d. for 12 weeks in addition to enzyme replacement therapy (ERT; the lucerastat group). Four patients with Fabry disease received ERT only. Eight patients reported 17 adverse events (AEs) in the lucerastat group. No clinically relevant safety abnormalities were observed. The mean (SD) levels of the plasma GSLs, glucosylceramide, lactosylceramide, and globotriaosylceramide, were significantly decreased from baseline in the lucerastat group (-49.0% (16.5%), -32.7% (13.0%), and -55.0% (10.4%), respectively). Lucerastat 1,000 mg b.i.d. was well tolerated in patients with Fabry disease over 12 weeks. A marked decrease in plasma GSLs was observed, suggesting clinical potential for lucerastat in patients with Fabry disease.

Structure-Based Discovery of Small Molecule Inhibitors of Cariogenic Virulence.

Streptococcus mutans employs a key virulence factor, three glucosyltransferase (GtfBCD) enzymes to establish cariogenic biofilms. Therefore, the inhibition of GtfBCD would provide anti-virulence therapeutics. Here a small molecule library of 500,000 small molecule compounds was screened in silico against the available crystal structure of the GtfC catalytic domain. Based on the predicted binding affinities and drug-like properties, small molecules were selected and evaluated for their ability to reduce S. mutans biofilms, as well as inhibit the activity of Gtfs. The most potent inhibitor was further characterized for Gtf binding using OctetRed instrument, which yielded low micromolar KD against GtfB and nanomolar KD against GtfC, demonstrating selectivity towards GtfC. Additionally, the lead compound did not affect the overall growth of S. mutans and commensal oral bacteria, and selectively inhibit the biofilm formation by S. mutans, indicative of its selectivity and non-bactericidal nature. The lead compound also effectively reduced cariogenicity in vivo in a rat model of dental caries. An analog that docked poorly in the GtfC catalytic domain failed to inhibit the activity of Gtfs and S. mutans biofilms, signifying the specificity of the lead compound. This report illustrates the validity and potential of structure-based design of anti-S. mutans virulence inhibitors.

Miglustat therapy in a case of early-infantile Niemann-Pick type C.

Niemann-Pick disease type C (NPC) is a rare, progressive autosomal recessive disease. It is caused by mutations in either the NPC1 or NPC2 genes, resulting in defective regulation of intracellular lipid trafficking. Miglustat, which reversibly inhibits glucosylceramide synthase, reportedly has beneficial effects on the progressive neurological symptoms of NPC and was approved in Japan in 2012. Some reports suggested that miglustat therapy delayed the onset or progression of NPC when treatment was initiated before the onset of neurological manifestation or at an early stage. We report here a patient with the early-infantile form of NPC who started on miglustat at 4months of ages. To our knowledge, this patient is the youngest reported patient with NPC in which miglustat therapy was initiated. Our patient, who had hypotonia and developmental delay before treatment, remained stable and showed no new neurological symptoms. In addition, pulmonary involvement was improved during miglustat therapy. Our case and previous reports underscore the importance of early initiation of miglustat therapy for NPC.

Inhibitory properties of 1,4-dideoxy-1,4-imino-d-arabinitol (DAB) derivatives acting on glycogen metabolising enzymes.

Glycogen synthase (GS) and glycogen phosphorylase (GP) are the key enzymes that control, respectively, the synthesis and degradation of glycogen, a multi-branched glucose polymer that serves as a form of energy storage in bacteria, fungi and animals. An abnormal glycogen metabolism is associated with several human diseases. Thus, GS and GP constitute adequate pharmacological targets to modulate cellular glycogen levels by means of their selective inhibition. The compound 1,4-dideoxy-1,4-imino-d-arabinitol (DAB) is a known potent inhibitor of GP. We studied the inhibitory effect of DAB, its enantiomer LAB, and 29 DAB derivatives on the activity of rat muscle glycogen phosphorylase (RMGP) and E. coli glycogen synthase (EcGS). The isoform 4 of sucrose synthase (SuSy4) from Solanum tuberosum L. was also included in the study for comparative purposes. Although these three enzymes possess highly conserved catalytic site architectures, the DAB derivatives analysed showed extremely diverse inhibitory potential. Subtle changes in the positions of crucial residues in their active sites are sufficient to discriminate among the structural differences of the tested inhibitors. For the two Leloir-type enzymes, EcGS and SuSy4, which use sugar nucleotides as donors, the inhibitory potency of the compounds analysed was synergistically enhanced by more than three orders of magnitude in the presence of ADP and UDP, respectively. Our results are consistent with a model in which these compounds bind to the subsite in the active centre of the enzymes that is normally occupied by the glucosyl residue which is transferred between donor and acceptor substrates. The ability to selectively inhibit the catalytic activity of the key enzymes of the glycogen metabolism may represent a new approach for the treatment of disorders of the glycogen metabolism.

Comparative effectiveness of echinocandins versus fluconazole therapy for the treatment of adult candidaemia due to Candida parapsilosis: a retrospective observational cohort study of the Mycoses Study Group (MSG-12).

OBJECTIVES: A polymorphism in the gene encoding ß-1,3-glucan synthase, the target of the echinocandin class of antifungals, results in increased in vitro MICs of the echinocandins. This has resulted in controversy surrounding use of the echinocandins for treatment of Candida parapsilosis candidaemia. We aimed to compare 30 day mortality in adults with C. parapsilosis candidaemia treated with echinocandins versus fluconazole. METHODS: This is a retrospective observational cohort study. We used the Premier Perspective Database to identify adult patients with C. parapsilosis candidaemia treated with only fluconazole or only an echinocandin as definitive therapy. The primary outcome was 30 day mortality. Propensity scores were derived to estimate the probability the patient would have received either an echinocandin or fluconazole. Inverse probability of treatment weighting (IPTW) was used in a weighted logistic regression to calculate odds of 30 day mortality. RESULTS: There were 307 unique patients with C. parapsilosis candidaemia. One hundred and twenty-six (41%) received fluconazole and 181 (59%) received an echinocandin. Age, gender, race, year of admission, need for ICU resources in the week prior to candidaemia onset, and receipt of vasopressors on the day of candidaemia onset were included in the propensity score model used to calculate inverse probability of treatment weights. Weighted logistic regression demonstrated no difference in 30 day mortality between patients receiving an echinocandin as compared with fluconazole (OR 0.82, 95% CI 0.33-2.07). CONCLUSIONS: Our result supports the 2016 IDSA invasive candidiasis guidelines, which no longer clearly favour treatment with fluconazole over an echinocandin for C. parapsilosis candidaemia.

N-butyldeoxynojirimycin treatment restores the innate fear response and improves learning in mucopolysaccharidosis IIIA mice.

UNLABELLED: Mucopolysaccharidosis IIIA is a heritable neurodegenerative disorder resulting from the dysfunction of the lysosomal hydrolase sulphamidase. This leads to the primary accumulation of the complex carbohydrate heparan sulphate in a wide range of tissues and the secondary neuronal storage of gangliosides GM2 and GM3 in the brain. GM2 storage is associated with CNS deterioration in the GM2 gangliosidosis group of lysosomal storage disorders and may also contribute to MPS CNS disease. N-butyldeoxynojirimycin, an inhibitor of ceramide glucosyltransferase activity and therefore of ganglioside synthesis, was administered to MPS IIIA mice both prior to maximal GM2 and GM3 accumulation (early treatment) and after the maximum level of ganglioside had accumulated in the brain (late treatment) to determine if behaviour was altered by ganglioside level. Ceramide glucosyltransferase activity was decreased in both treatment groups; however, brain ganglioside levels were only decreased in the late treatment group. Learning in the water cross maze was improved in both groups and the innate fear response was also restored in both groups. A reduction in the expression of inflammatory gene Ccl3 was observed in the early treatment group, while IL1ß expression was reduced in both treatment groups. Thus, it appears that NB-DNJ elicits a transient decrease in brain ganglioside levels, some modulation of inflammatory cytokines and a functional improvement in behaviour that can be elicited both before and after overt neurological changes manifest. SYNOPSIS: NB-DNJ improves learning and restores the innate fear response in MPS IIIA mice by decreasing ceramide glucosyltransferase activity and transiently reducing ganglioside storage and/or modulating inflammatory signals.

Pharmacodynamic target evaluation of a novel oral glucan synthase inhibitor, SCY-078 (MK-3118), using an in vivo murine invasive candidiasis model.

Echinocandins inhibit the synthesis of ß-1,3-D-glucan in Candida and are the first-line therapy in numerous clinical settings. Their use is limited by poor oral bioavailability, and they are available only as intravenous therapies. Derivatives of enfumafungin are novel orally bioavailable glucan synthase inhibitors. We performed an in vivo pharmacodynamic (PD) evaluation with a novel enfumafungin derivative, SCY-078 (formerly MK-3118), in a well-established neutropenic murine model of invasive candidiasis against C. albicans, C. glabrata, and C. parapsilosis. The SCY-078 MICs varied 8-fold. Oral doses of 3.125 to 200 mg/kg SCY-078 salt in sterile water produced peak levels of 0.04 to 2.66 µg/ml, elimination half-lives of 5.8 to 8.5 h, areas under the concentration-time curve from 0 to 24 h (AUC0-24 h) of 0.61 to 41.10 µg·h/ml, and AUC from 0 to infinity (AUC0-∞) values of 0.68 to 40.31 µg·h/ml. The pharmacokinetics (PK) were approximately linear over the dose range studied. Maximum response (Emax) and PK/PD target identification studies were performed with 4 C. albicans, 4 C. glabrata, and 3 C. parapsilosis isolates. The PD index AUC/MIC was explored by using total (tAUC) and free (fAUC) drug concentrations. The maximum responses were 4.0, 4.0, and 4.3 log10 CFU/kidney reductions for C. albicans, C. glabrata, and C. parapsilosis, respectively. The AUC/MIC was a robust predictor of efficacy (R2, 0.53 to 0.91). The 24-h PD targets were a static dose of 63.5 mg/kg, a tAUC/MIC of 500, and an fAUC/MIC of 1.0 for C. albicans; a static dose of 58.4 mg/kg, a tAUC/MIC of 315, and an fAUC/MIC of 0.63 for C. glabrata; and a static dose of 84.4 mg/kg, a tAUC/MIC of 198, and an fAUC/MIC of 0.40 for C. parapsilosis. The mean fAUC/MIC values associated with a 1-log kill endpoint against these species were 1.42, 1.26, and 0.91 for C. albicans, C. glabrata, and C. parapsilosis, respectively. The static and 1-log kill endpoints were measured relative to the burden at the start of therapy. The static and 1-log kill doses, as well as the total and free drug AUC/MIC PD targets, were not statistically different between species but were numerically lower than those observed for echinocandins. SCY-078 is a promising novel oral glucan synthase inhibitor against Candida species, and further investigation is warranted.

Preventive effects of an original combination of grape seed polyphenols with amine fluoride on dental biofilm formation and oxidative damage by oral bacteria.

AIMS: To investigate the preventive effects of an original combination of a grape seed extract (GSE) with an amine fluoride (Fluorinol(®) ) on dental plaque formation and oxidative damage caused by oral bacteria. METHODS AND RESULTS: The antibacterial activity of the compounds was assessed using the broth macrodilution method, and their antiplaque activity was evaluated on a multispecies biofilm grown on saliva-coated hydroxyapatite discs. The effect on glucosyltransferases activity was analysed through reductions in the overall reaction and the quantity of insoluble glucan synthesized. The combination of 2000 µg ml(-1) of GSE with 10·2 mg ml(-1) of Fluorinol(®) significantly decreased the biofilm formation (up to 4·76 log10 of reduction) and inhibited by 97·4% the insoluble glucan synthesis by glucosyltransferases. The antioxidant activity of this combination, alone or incorporated into a formulated mouthwash (Eludril daily(®) ), was determined using the Trolox equivalent antioxidant capacity assay (TEAC), and both showed significantly greater antioxidant capacity than vitamin C. CONCLUSIONS: The GSE/Fluorinol(®) combination showed both a significant antiplaque activity and an important antioxidant capacity in vitro, without any bactericidal effects. SIGNIFICANCE AND IMPACT OF THE STUDY: This is, to our knowledge, the first report on the properties of an original combination of a polyphenolic extract with amine fluoride that could be used for the prevention of oral diseases and oxidative damage associated.

A small molecule inhibitor of Bcl-2, HA14-1, also inhibits ceramide glucosyltransferase.

HA14-1 is a Bcl-2 inhibitor that is widely used for studies of apoptosis. In the course of searching for a ceramide glucosyltransferase inhibitor that catalyzes the first glycosylation step of glycosphingolipid synthesis, we unexpectedly found that HA-14-1 also has the ability to inhibit ceramide glucosyltransferase. The IC50 value of HA14-1 against ceramide glucosyltransferase is 4.5µM, which is lower than that reported for Bcl-2 in vitro. Kinetic analyses revealed that HA14-1 is a competitive and mixed-type inhibitor with respect to C6-NBD-ceramide and UDP-glucose, respectively.

Initiation and discontinuation of substrate inhibitor treatment in patients with Niemann-Pick type C disease.

Niemann-Pick type C disease (NP-C) is a lysosomal storage disorder characterized by a progressive neurological deterioration. Different clinical forms have been defined based on patient age at neurological symptoms onset: perinatal, early infantile (EI), late infantile (LI), juvenile and adult. There is no curative treatment for NP-C. Miglustat is the first effective therapy for the neurological manifestations of NP-C patients, as it can slow down the progression of the disease. Our aim is to establish recommendations on the initiation and discontinuations with miglustat therapy based on the modified disability scale scores and describe therapeutic options to prevent treatment-related adverse effects. Four patients with different clinical forms of NP-C are reported. The modified disability scale was applied at baseline and treatment on follow up. Treatment with miglustat was initiated in patient 1 (EI form) at onset of delayed speech. Patient 2 (LI form) who started miglustat therapy in the advanced stage of the disease, died 2 years thereafter. Patient 3 (juvenile form) started treatment with miglustat at diagnosis and remains stable at four years on follow up. Patient 4, asymptomatic, is not currently treated. Miglustat has demonstrated efficacy to slow down the neurological impairment in NP-C patients assessed by the modified disability scale. Miglustat should be initiated at the onset of the first neurological symptoms. Disability scores above 20 reflect an advanced neurological impairment of the disease and miglustat therapy should be discontinued or not initiated. The gastrointestinal adverse effects can be prevented by dose titration and dietary modifications.