Discovery of Novel UDP-N-Acetylglucosamine Acyltransferase (LpxA) Inhibitors with Activity against Pseudomonas aeruginosa

This study describes a novel series of UDP-N-acetylglucosamine acyltransferase (LpxA) inhibitors that was identified through affinity-mediated selection from a DNA-encoded compound library. The original hit was a selective inhibitor of Pseudomonas aeruginosa LpxA with no activity against Escherichia coli LpxA. The biochemical potency of the series was optimized through an X-ray crystallography-supported medicinal chemistry program, resulting in compounds with nanomolar activity against P. aeruginosa LpxA (best half-maximal inhibitory concentration (IC₅₀) <5 nM) and cellular activity against P. aeruginosa (best minimal inhibitory concentration (MIC) of 4 μg/mL). Lack of activity against E. coli was maintained (IC₅₀ > 20 μM and MIC > 128 μg/mL). The mode of action of analogues was confirmed through genetic analyses. As expected, compounds were active against multidrug-resistant isolates. Further optimization of pharmacokinetics is needed before efficacy studies in mouse infection models can be attempted. To our knowledge, this is the first reported LpxA inhibitor series with selective activity against P. aeruginosa.

Differential expression levels of CD151 enable enrichment of atrial cardiomyocytes derived from human induced-pluripotent stem cell

Introduction

Human iPSCs-derived cardiomyocytes (hiPSCs-CMs) are heterogeneous populations that contain ventricular-like CMs (VCMs), atrial-like CMs (ACMs) and pacemaker cells. Isolation of pure populations of each hiPSCs-CM subtype corresponding to the target regions of the heart enables effective drug screening process and stable engraftment of hiPSCs-CMs (e.g. ventricular cardiomyocytes without impurities).

Purpose

Atrial and ventricular cardiomyocytes develop from distinct mesoderm populations, and many of different genes are expressed between two subtypes. Since our method of cardiomyocytes differentiation from hiPSCs mimics in vivo cardiomyocytes development, we hypothesized that two subtypes could be separated by differentially expressed genes in hiPSCs-CMs differentiation process. In this study, we focused cell surface genes which are useful for analysis by flow cytometry, and then identified cell surface marker that can distinguish atrial and ventricular cardiomyocytes from hiPSCs-CMs.

Methods

We performed an antibody-based screening using hiPSCs-CMs induced under atrial induction condition (AIC) and ventricular induction condition (VIC) by flow cytometry. To identify cell surface markers which enable discrimination of cardiac subtypes, we isolated the cell populations using the antibodies against the cell surface markers. Quantitative PCR was performed to analyze expression levels of subtype-specific genes in sorted cells. We confirmed subtype classification of cells using patch-clamp method.

Results

We identified CD151 as a novel candidate of atrial/ventricular selectable marker. The expression level of CD151 was low in most hiPSCs-CMs under AIC. In these cells, CD151-low cells highly expressed atrial genes compared to CD151-high cells. In contrast, the expression level of CD151 was high in most hiPSCs-CMs under VIC. In these cells, CD151-high cells highly expressed ventricular genes compared to CD151-low cells. Furthermore, we investigated the electrophysiological properties of CD151-high and -low cells using patch-clamp experiments. As expected, the cells showing atrial type action potential were enriched in AIC with low expression of CD151 (n=17). On the other hand, CD151-high cells (n=16) contained no atrial CMs, but mostly nodal like cells. In addition, CD151-low cells in AIC were affected with action potential duration by exposure of atrial specific channel blocker (4-aminopyridine) and activator (carbachol). In VIC, CD151-high cells (n=16) demonstrated ventricular type action potential property compared to CD151-low cells (n=21).

Conclusion

These results suggest that CD151 is a useful marker which can enrich ACMs from hiPSCs-CMs. Because these enriched ACMs are uniform population, it may be appropriate for atrial-selective drug screening. Additionally, this marker can reduce contaminated ACMs from hiPSCs-CMs cultured in VIC.

Action potential of CD151-high/low CMs

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): Takeda pharmaceutical company limited, Japan society for the promotion of science(JSPS) KAKENHI

p53, Cyclin D1, p21 (WAF1) and Ki-67 (MIB1) Expression at Invasive Tumour Fronts of Oral Squamous Cell Carcinomas and Development of Local Recurrence

BACKGROUND

Expression of p53, cyclin D1, p21 (WAF1) and Ki-67 (MIB1) was evaluated in oral squamous cell carcinoma (OSCC) to test whether levels of these markers at invasive tumour fronts (ITFs) could predict the development of local recurrence.

MATERIALS AND METHODS

Archived paraffin-embedded specimens from 51 patients with T1/T2 tumours were stained immunohistochemically and analysed quantitatively. Local recurrence-free survival was tested with Kaplan-Meier survival plots (log-rank test) using median values to define low and high expression groups and with a Cox's proportional hazards model in which the expression scores were entered as continuous variables.

RESULTS

The assessment of expression of all markers was highly reliable, univariate analysis showing that patients with clear surgical margins, with low cyclin D1 and high p21 expression at the ITF had the best local recurrence-free survival. Multivariate analysis showed that these three parameters were independent prognostic factors but that neither p53 nor MIB1 expression were of prognostic value.

CONCLUSIONS

Assessment of p53, cyclin D1, p21 (WAF1), and Ki-67 (MIB1) at the ITF could help to predict local recurrence in early stage oral squamous cell carcinoma cases.

A new class of 5-HT2B antagonists possesses favorable potency, selectivity, and rat pharmacokinetic properties

We have been exploring the potential of 5-HT(2B) antagonists as a therapy for chronic heart failure. To assess the potential of this therapeutic approach, we sought compounds possessing the following attributes: (a) potent and selective antagonism of the 5-HT(2B) receptor, (b) low impact of serum proteins on potency, and (c) desirable pharmacokinetic properties. This Letter describes our investigation of a biphenyl benzimidazole class of compounds that resulted in 5-HT(2B) antagonists possessing the above attributes. Improving potency in a human serum albumin shift assay proved to be the most significant SAR discovery.

Anti-leukemia activity of CD33-specific chimeric cytotoxic T lymphocytes in vitro and in vivo is impaired by addition of the CD28 costimulatory endodomain

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Background: EBV-specific cytotoxic T cells (EBV-CTLs) expand and have long-term activity in vivo due to the sustained costimulation provided by the EBV-infected cells produced by this persistent virus. We exploited this phenomenon and redirected EBV-CTLs against CD33, a surface protein expressed on the malignant blasts of acute myeloid leukemia (AML) cells. Methods: EBV-CTLs generated from six EBV-seropositive donors were transduced using a retroviral vector encoding CD33 specific chimeric receptor (cR). We evaluated whether the high and sustained activity shown against native EBV+ target cells can be extended to the CD33+ EBV- targets of the chimeric receptor and whether the addition of CD28 signaling domain improved the receptor activity. Results: cRCD33-EBV-CTL maintained killed EBV-LCL and CD33+ targets (specific lysis respectively of 30% and 35% at E:T ratio 25:1). They produced Th-1, Th-2 and Tc cytokines on exposure to CD33+ targets. Addition of the CD28 intracellular domain did not increase cytotoxicity to CD33+ targets. Preincubation of CD33+ cells with the CD33-blocking MoAb resulted in up to 40% inhibition of lysis and up to 60% inhibition of cytokine release by cRCD33-EBV-CTLs confirming the specificity of the TCR interactions with CD33. NOD-SCID mice bearing a human CD33+ AML were injected with EBV-CTLs ×4 weekly starting 5 days after tumor inoculation. Significant tumor reduction was only observed in mice treated with the cRCD33-EBV-CTLs (p<0.05). Immunohistologic analysis showed the presence of a majority of CD8+ human T cells in the tumors of treated mice. Incorporation of the CD28 endodomain resulted in less tumor-infiltrating T cells in mice treated with cRCD33CD28-EBV-CTLs. There was no significant difference in the chemokines receptor expression on cRCD33CD28-EBV-CTLs but their rate of apoptosis was 16 % higher (p<0.05) than the one of cRCD33-EBV-CTLs. Conclusions: EBV- CTL expressing the CD33 chimeric receptor are functional in vitro and in vivo in mice. CD28 signaling may have a deleterious role for the activity of chimeric receptors in vivo.

No significant financial relationships to disclose.

Novel 2-aminopyrimidine carbamates as potent and orally active inhibitors of Lck: synthesis, SAR, and in vivo antiinflammatory activity

The lymphocyte-specific kinase (Lck) is a cytoplasmic tyrosine kinase of the Src family expressed in T cells and NK cells. Genetic evidence in both mice and humans demonstrates that Lck kinase activity is critical for signaling mediated by the T cell receptor (TCR), which leads to normal T cell development and activation. A small molecule inhibitor of Lck is expected to be useful in the treatment of T cell-mediated autoimmune and inflammatory disorders and/or organ transplant rejection. In this paper, we describe the synthesis, structure-activity relationships, and pharmacological characterization of 2-aminopyrimidine carbamates, a new class of compounds with potent and selective inhibition of Lck. The most promising compound of this series, 2,6-dimethylphenyl 2-((3,5-bis(methyloxy)-4-((3-(4-methyl-1-piperazinyl)propyl)oxy)phenyl)amino)-4-pyrimidinyl(2,4-bis(methyloxy)phenyl)carbamate (43) exhibits good activity when evaluated in in vitro assays and in an in vivo model of T cell activation.

Something not quite right: Gardner syndrome diagnosed by multiple cutaneous lesions and genetic testing

Gardner syndrome is a variant of familial adenomatous polyposis characterized by intestinal adenomatous polyps, which can progress to adenocarcinoma, and a variety of extraintestinal manifestations, including skin cysts, osteomas, soft tissue fibrous tumours and a characteristic ocular lesion. The extraintestinal manifestations are often the presenting feature but are usually not sufficiently characteristic on their own to trigger recognition of the syndrome. We report a case of a 17-year-old female who had been treated by a number of specialists over a 13-year period for a variety of cutaneous lesions without a hereditary condition being suspected. Gardner syndrome was considered only after excision of subcutaneous fibrous tumours from the mastoid region and paraspinal area and was confirmed by genetic testing in spite of the patient's refusal to undergo colonic endoscopic examination. Subsequent resection revealed approximately 70 adenomatous colonic polyps in the colon and rectum but no invasive tumour, highlighting the benefits of genetic testing in treatment planning.

Bcl-2 expression in sequential biopsies of potentially malignant oral mucosal lesions assessed by immunocytochemistry

OBJECTIVE

To examine, for the first time Bcl-2 expression in sequential (autogenous) oral mucosal biopsies taken from the same sites in a gender, risk-factor matched, Caucasoid sample, over a 21-year period.

DESIGN

Retrospective immunocytochemical longitudinal study of archival serial biopsies.

MATERIALS AND METHODS

Computer records were used to identify biopsy specimens derived from 12 patients. These were divided into four groups: (1) Histologically innocuous lesions which remained histologically innocuous. (2) Dysplastic lesions which remained dysplastic. (3) Histologically innocuous lesions which later progressed to squamous cell carcinoma (SCC). (4) Dysplastic lesions which later progressed to SCC. This represented 65 biopsies in total. Bcl-2 expression was studied using mouse antihuman BCL-2 oncoprotein clone 124 (Dako, Denmark).

RESULTS

Generally, there was a lack of Bcl-2 immunoreactivity in the epithelium, with one exception in dysplastic epithelium from a group (3) patient.

CONCLUSION

These findings suggest that in our series, Bcl-2 is not expressed early in oral premalignant lesions and appears to contradict previous reports. Possible explanations for this disparity are considered.

Common Components of Industrial Metal-Working Fluids as Sources of Carbon for Bacterial Growth

Water-based metal-working fluids used in large-scale industrial operations consist of many components, but in the most commonly used formulations only three classes of components are present in high enough concentrations that they could, in principle, provide enough carbon to support the high bacterial densities (10 9 CFU/ml) often observed in contaminated factory fluids. These components are petroleum oil (1 to 5%), petroleum sulfonates (0.1 to 0.5%), and fatty acids (less than 0.1%, mainly linoleic and oleic acids supplied as tall oils). We isolated pure strains of predominating bacteria from contaminated reservoirs of two metal-working systems and randomly selected 12 strains which we tested in liquid culture for growth with each of the metal-working fluid components as the sole source of carbon. Of the 12 strains, 7 reached high density (10 9 CFU/ml from an initial inoculum of less than 2 × 10 3 ) in 24 h, and 1 strain did the same in 48 h with 0.05% oleic or linoleic acid as the carbon source. These same strains also grew on 1% naphthenic petroleum oil but required up to 72 h to reach densities near 10 8 CFU/ml. One strain grew slightly and the others not at all on the petroleum sulfonates. The four remaining strains did not grow on any of the components, even though they were among the predominating bacteria in the contaminated system. Of the seven strains that grew best on the fatty acids and on the naphthenic petroleum oil, five were tentatively identified as Acinetobacter species and two were identified as Pseudomonas species. Four of the bacteria that did not grow were tentatively identified as species of Pseudomonas , and one could not be identified.