P4487Inhibition of aortic valve calcification by SNF472 in vitro

Background

Calcific aortic valve disease is the 2nd most frequent cause of open heart surgery. The valve interstitial cells (VIC) are crucial for calcification. SNF472 (a derivative of phytic acid) is a calcification inhibitor currently in clinical development for the treatment of cardiovascular calcification (Phase 2 CaLIPSO trial, EudraCT 2016–002834–59). SNF472 has been shown to inhibit vascular calcification in several preclinical models.

Purpose

1. Establish a new model of calcification in cultured human VIC; 2. Investigate whether SNF472 would inhibit calcification in this model, and 3. Study if SNF472 might inhibit ongoing calcification processes.

Methods

Healthy and calcified aortic valves were obtained from heart transplant recipients and patients undergoing aortic valve replacement due to calcific valve disease, respectively. VIC were isolated and seeded in basic growth medium, osteogenic differentiation medium (Osteodiff) alone, and with addition of different concentrations of SNF472. The following series of studies were performed: 1. VIC from healthy and calcified valves were cultured for three weeks with Osteodiff; 2. VIC from calcified valves were cultured for 3 weeks in Osteodiff media with 0, 1, 3, 10, 30, or 100 μM SNF472; 3. VIC from calcified valves were cultured for 3 weeks in Osteodiff media in total, but after 1 or 2 weeks 30 or 100 μM SNF472 was added to the cultures (n=8). Calcification was visualized by Alzarin Red staining and quantified by spectrophotometry. Statistics analysis was performed nonparametric One-Way ANOVA (Friedman and Kruskal–Wallis tests) with Dunn's post-test.

Results

Calcification was found to be 30% stronger in cultures of VIC from calcified valves as compared to cultured VIC from healthy valves (p=0.03). SNF472 successfully inhibited VIC calcification in a dose-dependent manner. SNF472 concentrations of 1, and 3 μM inhibited calcification by 7% (not significant) and 66% (p=0.08) respectively. Concentrations of 10, 30, and 100 μM completely inhibited calcification. 30 and 100 μM of SNF472 added after 1 week reduced ongoing calcification by 84% (p<0.01) and 100% (p<0.01) respectively. When given after 2 weeks of ongoing calcification non-significant inhibition was still observed (21 and 30%, respectively).

Conclusions

VIC from calcified valves have a more pro-calcification phenotype than VIC from healthy valves. SNF472 is able to inhibit the development VIC calcification in vitro. By early intervention SNF472 is also able to stop the progression of ongoing calcification. SNF472 shows to be a promising therapy to treat heart valve calcification.

Acknowledgement/Funding

EC FP7 (GA 609020), Balearic Islands Government grant (ES01/TCAI/41_2017), FEDER 2014-2020, Laboratoris Sanifit, Palma, Spain; University of Oslo

SNF472, a novel anti-crystallization agent, inhibits induced calcification in an in vitro model of human aortic valve calcification

The purpose of the present study was to investigate whether SNF472, the hexasodium salt of myo-inositol hexaphosphate (IP6 or phytate): 1. Inhibits induced calcification in cultured aortic valve interstitial cells (VIC) as an in vitro model of aortic valve stenosis and 2. Whether inhibition is different in VIC obtained from healthy and calcified aortic valves. VIC from healthy (n = 5) and calcified (n = 7) human aortic valves were seeded in basic growth medium, osteogenic differentiation medium alone, or in osteogenic medium with SNF472 (3, 10, and 30 μM) and cultivated for 3 weeks. Calcification was quantified spectrophotometrically after Alizarin Red staining. In VIC from calcified valves, a complete inhibition of calcification was observed with SNF472 concentrations of 10 and 30 μM (p < .01), significantly stronger than in VIC from healthy valves. When SNF472 was added to VIC after 1 week in osteogenic medium, 30 and 100 μM SNF472 inhibited the progression of ongoing calcification by 81 and 100% (p < .01), respectively. The same concentrations of SNF472 given after 2 weeks reduced calcification by 35 and 40% respectively (not significant). SNF472 inhibited both the formation and the progression of calcification with the strongest effect in VIC from calcified valves.

First-time-in-human randomized clinical trial in healthy volunteers and haemodialysis patients with SNF472, a novel inhibitor of vascular calcification

AIMS

SNF472 is a calcification inhibitor being developed for the treatment of cardiovascular calcification in haemodialysis (HD) and in calciphylaxis patients. This study investigated the safety, tolerability and pharmacokinetics (PK) of intravenous (IV) SNF472 in healthy volunteers (HV) and HD patients.

METHODS

This is a first-time-in-human, double-blind, randomized, placebo-controlled Phase I study to assess the safety, tolerability and PK of SNF472 after ascending single IV doses in HV and a single IV dose in HD patients. A pharmacodynamic analysis was performed to assess the capability of IV SNF472 to inhibit hydroxyapatite formation.

RESULTS

Twenty HV and eight HD patients were enrolled. The starting dose in HV was 0.5 mg kg^-1 and the dose ascended to 12.5 mg kg^-1 . The dose selected for HD patients was 9 mg kg^-1 . Safety analyses support the safety and tolerability of IV SNF472 in HD patients and HV. Most treatment-emergent adverse events were mild in intensity. No clinically significant effects were observed on vital signs or laboratory tests. PK results were similar in HD patients and HV and indicate a lack of significant dialysability. Pharmacodynamic analyses demonstrated that SNF472 administration reduced hydroxyapatite crystallization potential in HD patients who received IV SNF472 9 mg kg^-1 by 80.0 ± 2.4% (mean ± standard error of the mean, 95% CI, 75.3-84.8) compared to placebo (8.7 ± 21.0%, P < 0.001, 95% CI, -32.4 to 49.7).

CONCLUSION

The results from this study showed acceptable safety and tolerability, and lack of significant dialysability of IV SNF472. It is a potential novel treatment for cardiovascular calcification in end-stage renal disease and calciphylaxis warranting further human studies.

SNF472, a novel inhibitor of vascular calcification, could be administered during hemodialysis to attain potentially therapeutic phytate levels

BACKGROUND

Cardiovascular calcification (CVC) is a major concern in hemodialysis (HD) and the loss of endogenous modulators of calcification seems involved in the process. Phytate is an endogenous crystallization inhibitor and its low molecular mass and high water solubility make it potentially dialyzable. SNF472 (the hexasodium salt of phytate) is being developed for the treatment of calciphylaxis and CVC in HD patients. We aimed to verify if phytate is lost during dialysis, and evaluate SNF472's behaviour during dialysis.

METHODS

Dialyzability was assessed in vitro using online-hemodiafiltration and high-flux HD systems in blood and saline. SNF472 was infused for 20 min and quantified at different time points.

RESULTS

Phytate completely dialyzed in 1 h at low concentrations (10 mg/l) but not when added at 30 or 66.67 mg/l SNF472. In bypass conditions, calcium was slightly chelated during SNF472 infusion but when the system was switched to dialysis mode the calcium in the bath compensated this chelation.

CONCLUSION

Phytate dialyses with a low clearance. The administration of SNF472 as an exogenous source of phytate allows to attain supra-physiological levels required for its potential therapeutic properties. As SNF472 is infused during the whole dialysis session, the low clearance would not affect the drug's systemic exposure.

A novel pharmacodynamic assay to evaluate the effects of crystallization inhibitors on calcium phosphate crystallization in human plasma

Cardiovascular calcification (CVC) is a progressive complication of chronic kidney disease and a predictor of CV events and mortality. The use of biomarkers to predict CV risk and activities of potential or current treatment drugs in these patients could have a crucial impact on therapeutic approaches. Our aim was to develop a novel assay for measurement of the rate of calcium phosphate crystallization in human plasma and provide a tool to evaluate the effects of crystallization inhibitors. The efficacy of inhibitors was determined by adding inhibitory compounds (polyphosphates, fetuin-A, sodium thiosulfate or citrate) to control samples. The assay was additionally validated for SNF472, an experimental formulation of phytate being developed for the treatment of calciphylaxis and CVC in patients with end-stage renal disease (ESRD) undergoing hemodialysis (HD). The method was repeatable and reproducible. The plasma crystallization rate was reduced up to 80% in a concentration-dependent manner following treatment with inhibitors in vitro, among which SNF472 was the most potent. This method appears beneficial in evaluating and discriminating between inhibitory activities of compounds such as polyphosphates on calcium phosphate crystallization, which present a novel therapeutic approach to treat CVC in ESRD patients.

Mutual interactions between an invasive bark beetle and its associated fungi

Interactions between invasive insects and their fungal associates have important effects on the behavior, reproductive success, population dynamics and evolution of the organisms involved. The red turpentine beetle (RTB), Dendroctonus valens LeConte (Coleoptera: Scolytinae), an invasive forest pest in China, is closely associated with fungi. By carrying fungi on specialized structures in the exoskeleton, RTB inoculates fungi in the phloem of pines (when females dig galleries for egg laying and when males join them for mating). After eggs hatch, larvae gregariously feed on the phloem colonized by the fungi. We examined the effects of five isolates of RTB associated fungi (two from North America, Leptographium terebrantis and L. procerum, and three from China, Ophiostoma minus, L. sinoprocerum and L. procerum) on larval feeding activity, development and mortality. We also studied the effects of volatile chemicals produced in the beetle hindgut on fungal growth. Ophiostoma minus impaired feeding activity and reduced weight in RTB larvae. Leptographium sinoprocerum, L. terebrantis and L. procerum did not dramatically influence larval feeding and development compared to fungi-free controls. Larval mortality was not influenced by any of the tested fungi. Hindgut volatiles of RTB larvae, verbenol, myrtenol and myrtenal, inhibited growth rate of all the fungi. Our results not only show that D. valens associated fungus, O. minus, can be detrimental to its larvae; but, most importantly, they also show that these notorious beetles have an outstanding adaptive response evidenced by the ability to produce volatiles that inhibit growth of harmful fungus.

In vivo and in vitro pharmacological characterization of SVT-40776, a novel M3 muscarinic receptor antagonist, for the treatment of overactive bladder

BACKGROUND AND PURPOSE

Highly selective M(3) muscarinic receptor antagonists may represent a better treatment for overactive bladder syndrome, diminishing side effects. Cardiac side effects of non-selective antimuscarinics have been associated with activity at M(2) receptors as these receptors are mainly responsible for muscarinic receptor-dependent bradycardia. We have investigated a novel antimuscarinic, SVT-40776, highly selective for M(3) over M(2) receptors (Ki = 0.19 nmol.L(-1) for M(3) receptor affinity). This study reports the functional activity of SVT-40776 in the bladder, relative to its activity in atria.

EXPERIMENTAL APPROACH

In vitro and ex vivo (oral dosing) inhibition of mouse detrusor and atrial contractile responses to carbachol were used to study the functional activity of SVT-40776. The in vivo efficacy of SVT-40776 was characterized by suppression of isovolumetric spontaneous bladder contractions in anaesthetized guinea pigs after intravenous administration.

KEY RESULTS

SVT-40776 was the most potent in inhibiting carbachol-induced bladder contractions of the anti-cholinergic agents tested, without affecting atrial contractions over the same range of concentrations. SVT-40776 exhibited the highest urinary versus cardiac selectivity (199-fold). In the guinea pig in vivo model, SVT-40776 inhibited 25% of spontaneous bladder contractions at a very low dose (6.97 microg.kg(-1) i.v), without affecting arterial blood pressure.

CONCLUSIONS AND IMPLICATIONS

SVT-40776 is a potent inhibitor of M(3) receptor-related detrusor contractile activity. The absence of effects on isolated atria preparations represents an interesting characteristic and suggests that SVT-40776 may lack unwanted cardiac effects; a feature especially relevant in a compound intended to treat mainly elderly patients.

Sequencing of the porB gene: a step toward a true characterization of Neisseria meningitidis

Variations in class 2/3 (PorB) proteins form the basis for meningococcal serotyping. Antibodies against these proteins are bactericidal, making serotyping results useful not only for epidemiological surveillance of meningococcal disease but also for identifying potential vaccine components. A total of 20 to 60% of meningococcal B and C isolates from any given population are nontypeable (NT) using a panel of monoclonal antibodies. To analyze the mechanisms responsible for the nonserotypeability characteristic in Neisseria meningitidis, we (i) established the nucleotide sequences of porB gene in 146 meningococcal strains (95 not recognized by the serotyping panel), (ii) identified 18 new allelic variants of the porB gene, (iii) correlated allelic variants with serotypes, (iv) suggest the nontypeability characteristic in those 95 NT strains, and (v) reject the possibility of variation in the levels of PorB expression.

Impact of the meningococcal C conjugate vaccine in Spain: an epidemiological and microbiological decision

The new meningococcal C conjugate vaccine became available in Spain and was included in the infant vaccination schedule in 2000. A catch-up campaign was carried out in children under six years of age. As a consequence, the incidence of meningococcal disease caused by serogroup C has fallen sharply during the last three epidemiological years in Spain. The risk of contracting serogroup C disease in 2002/2003 fell by 58% when compared with the season before the conjugate vaccine was introduced. There was also an important decrease in mortality. Three deaths due to serogroup C occurred in the age groups targeted for vaccination in 2002/2003, compared with 30 deaths in the same age groups in the season before the launch of the vaccine campaign. In the catch-up campaign the vaccine coverage reached values above 92%. For the 2001, 2002 and 2003 routine childhood immunisation programme coverage values ranged from 90% to 95%. During the past three years a total of 111 cases of serogroup C disease have been reported in patients in the vaccine target group. Most of the vaccination failures occurred during the epidemiological year 2002/2003. Eight (53%) vaccine failures occurred in children who had been routinely immunised in infancy, and could be related to a lost of protection with time since vaccination. The isolation of several B:2a:P1.5 strains (ST-11 lineage) is noteworthy. These may have their origin in C:2a:P1.5 strains which, after undergoing genetic recombination at the capsular operon level, express serogroup B. These strains could have relevant epidemic potential.

Impact of the meningococcal C conjugate vaccine in Spain: an epidemiological and microbiological decision

The new meningococcal C conjugate vaccine became available in Spain and was included in the infant vaccination schedule in 2000. A catch-up campaign was carried out in children under six years of age. As a consequence, the incidence of meningococcal disease caused by serogroup C has fallen sharply during the last three epidemiological years in Spain. The risk of contracting serogroup C disease in 2002/2003 fell by 58% when compared with the season before the conjugate vaccine was introduced. There was also an important decrease in mortality. Three deaths due to serogroup C occurred in the age groups targeted for vaccination in 2002/2003, compared with 30 deaths in the same age groups in the season before the launch of the vaccine campaign. In the catch-up campaign the vaccine coverage reached values above 92%. For the 2001, 2002 and 2003 routine childhood immunisation programme coverage values ranged from 90% to 95%. During the past three years a total of 111 cases of serogroup C disease have been reported in patients in the vaccine target group. Most of the vaccination failures occurred during the epidemiological year 2002/2003. Eight (53%) vaccine failures occurred in children who had been routinely immunised in infancy, and could be related to a lost of protection with time since vaccination. The isolation of several B:2a:P1.5 strains (ST-11 lineage) is noteworthy. These may have their origin in C:2a:P1.5 strains which, after undergoing genetic recombination at the capsular operon level, express serogroup B. These strains could have relevant epidemic potential.

Molecular characterization of ciprofloxacin resistance of gonococcal strains in Spain

BACKGROUND

Over the past several years, the emergence of gonococcal isolates with intermediate or full resistance to fluoroquinolones has become a significant concern in several countries, including Spain.

GOAL

The goal was to determine the occurrence of ciprofloxacin resistance among Neisseria gonorrhoeae strains in Spain during 2000 to 2001 and determine the frequency and patterns of mutations at gyrA, gyrB, and parC genes in these isolates.

STUDY DESIGN

Eleven ciprofloxacin-resistant strains (with MICs ranging from 1 to 64 micrograms/mL) and two intermediate isolates (with MICs of 0.12 and 0.5 microgram/mL) were found. Mutations were identified by polymerase chain reaction and direct sequencing of the amplified products.

RESULTS AND CONCLUSIONS

Alterations at Ser-91 and Asp-95 in GyrA were detected in all strains except one, an isolate for which the MIC was 0.12 microgram/mL. Alterations in ParC were more variable, and there was no clear correlation between the number of parC mutations and the level of resistance. No alterations at gyrB gene associated with ciprofloxacin resistance were found. The resistance was distributed among different types of strains, suggesting that the increase in the incidence of ciprofloxacin-resistant strains in Spain was not exclusively due to the appearance of a single-strain outbreak.

Development of a multilocus sequence typing method for analysis of Listeria monocytogenes clones

This study is a first step in the development of multilocus sequence typing (MLST) method for Listeria monocytogenes. Nine housekeeping genes were analyzed in a set of 62 strains isolated from different sources and geographic locations in Spain. These strains were previously characterized by pulsed-field gel electrophoresis (PFGE). Because of low diversity, two loci were discarded from the study. The sequence analysis of the seven remaining genes showed 29 different allelic combinations, with 22 of them represented by only one strain. The results of this sequence analysis were generally consistent with those of PFGE. Because MLST allows the easy comparison and exchange of results obtained in different laboratories, the future application of this new molecular method could be a useful tool for the listeriosis surveillance systems that will allow the identification and distribution of analysis of L. monocytogenes clones in the environment.

Antibiotic resistance of Neisseria gonorrhoeae in Spain: trends over the last two decades

In vitro activities of six antimicrobial agents against 2966 strains of Neisseria gonorrhoeae, isolated in Spain between 1983 and 2001, were determined. The percentages of intermediately susceptible and resistant isolates to penicillin (MIC > or = 0.12 mg/L) and tetracycline (MIC > or = 0.5 mg/L) were very high over the period of study. Strains intermediately susceptible to cefoxitin were identified at a variable percentage during the study. All N. gonorrhoeae isolates were susceptible to spectinomycin and ceftriaxone. Recently, resistance to ciprofloxacin has emerged.

The epidemic wave of meningococcal disease in Spain in 1996-1997: probably a consequence of strain displacement

During 1996 and 1997 an epidemic wave of meningococcal disease took place in Spain. Initial studies described the antigenic expression of the epidemic strain as C:2b:P1.2,5 and proposed that it was a variant of the previously identified Spanish C:2b:non-subtypable epidemic strain. To clarify this hypothesis, 1036 C:2b:P1.2(5) and 76 C:2b:NST isolates obtained during 1992-1999 were analysed by pulsed-field gel electrophoresis. The majority of the C:2b:P1.2,5 and C:2b:P1.2 isolates showed one of two very closely related profiles. During the epidemic period, 80% of the C:2b:NST strains showed these two pulsotypes. However, before the epidemic wave, most of these C:2b:NST strains (60%) showed a profile that was found infrequently among C:2b:P1.2,5 and C:2b:P1.2 isolates. A similar evolution was observed in C:2b:P1.5 isolates. Thirty-four C:2b:P1.2(5) and 10 C:2b:NST isolates, exhibiting representative pulsotypes, were subjected to multi-locus sequence typing. Isolates belonging to both A4 and ET-37 lineages were identified. These data point to the possibility that the A4 cluster has displaced the ET-37 complex among serogroup C meningococci in Spain.

Medulloblastomas in neurofibromatosis type 1. Case report and literature review

A 6-year-old girl, previously diagnosed with neurofibromatosis type 1 (NF-1) presented with ataxia and symptoms of raised intracranial pressure. Diagnostic work up disclosed a posterior fossa tumor. Histopathological study of the excised neoplasm showed a cerebellar medulloblastoma. We review the current literature and suggest that the association of medulloblastoma with NF-1 is not a chance occurrence, and that it might be pathogenically related. We propose that medulloblastoma should be added to the list of malignancies that are apt to occur in NF-1.

What about antibiotic resistance in Neisseria lactamica?

The in vitro activity of penicillin, ampicillin, cefotaxime, ceftriaxone, rifampicin and ciprofloxacin against 286 Neisseria lactamica isolates was determined by agar dilution and the category of susceptibility was analysed in accordance with the criteria used for Neisseria meningitidis. All isolates were considered to have intermediate susceptibility to penicillin. A total of 1.7% of the isolates were resistant to ampicillin but all were susceptible to cefotaxime and ceftriaxone. Rifampicin MICs ranged between 0.12 and 2 mg/L. Six isolates (2.1%) showed decreased susceptibility to ciprofloxacin.