Use of 3D Human Liver Organoids to Predict Drug-Induced Phospholipidosis.

Drug-induced phospholipidosis (PL) is a storage disorder caused by the formation of phospholipid-drug complexes in lysosomes. Because of the diversity of PL between species, human cell-based assays have been used to predict drug-induced PL in humans. We established three-dimensional (3D) human liver organoids as described previously and investigated their liver characteristics through multiple analyses. Drug-induced PL was initiated in these organoids and in monolayer HepG2 cultures, and cellular changes were systemically examined. Organoids that underwent differentiation showed characteristics of hepatocytes rather than HepG2 cells. The organoids also survived under PL-inducing drug conditions for 48 h and maintained a more stable albumin secretion level than the HepG2 cells. More cytoplasmic vacuoles were observed in organoids and HepG2 cells treated with more potent PL-induced drugs, but to a greater extent in organoids than in HepG2 cells. Lysosome-associated membrane protein 2, a marker of lysosome membranes, showed a stronger immunohistochemical signal in the organoids. PL-distinctive lamellar bodies were observed only in amiodarone-treated organoids by transmission electron microscopy. Human liver organoids are thus more sensitive to drug-induced PL and less affected by cytotoxicity than HepG2 cells. Since PL is a chronic condition, these results indicate that organoids better reflect metabolite-mediated hepatotoxicity in vivo and could be a valuable system for evaluating the phospholipidogenic effects of different compounds during drug development.

Expression and characterization of glutamate decarboxylase from Lactobacillus brevis HYE1 isolated from kimchi.

A putative gene (gadlbhye1) encoding glutamate decarboxylase (GAD) was cloned from Lactobacillus brevis HYE1 isolated from kimchi, a traditional Korean fermented vegetable. The amino acid sequences of GADLbHYE1 showed 48% homology with the GadA family and 99% identity with the GadB family from L. brevis. The cloned GADLbHYE1 was functionally expressed in Escherichia coli using inducible expression vectors. The expressed recombinant GADLbHYE1 was successfully purified by Ni-NTA affinity chromatography, and had a molecular mass of 54 kDa with optimal hydrolysis activity at 55 °C and pH 4.0. Its thermal stability was determined to be higher than that of other GADs from L. brevis, based on its melting temperature (75.18 °C). Kinetic parameters including Km and Vmax values for GADLbHYE1 were 4.99 mmol/L and 0.224 mmol/L/min, respectively. In addition, the production of gamma-aminobutyric acid in E. coli BL21 harboring gadlbhye1/pET28a was increased by adding pyridoxine as a cheaper coenzyme.

Paenibacillus arcticus sp. nov., isolated from Arctic soil.

A Gram-positive, endospore-forming, strictly aerobic and rod-shaped bacterium, designated strain MME2_R6T, was isolated from Arctic soil, and it was identified by using a polyphasic taxonomic approach. This strain was psychrotolerant, growing at 4‒24 °C. 16S rRNA gene sequence analysis showed that strain MME2_R6T was closest to Paenibacillus swuensis DY6T, with 93.9 % similarity. However, in phylogenetic analysis based on the 16S rRNA gene sequence, strain MME2_R6T showed that it clustered with Paenibacillus contaminans CKOBP-6T and the sequencing similarity between the two species was 93.7 %. Its major cellular fatty acid was anteiso-C15 : 0, like other Paenibacillus species. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The predominant isoprenoid quinone was menaquinone-7. The diagnostic diamino acid in the cell wall was meso-diaminopimelic acid. The genomic DNA G+C content was 44.2 mol%. Based on the results of phenotypic, chemotaxonomic and phylogenetic analyses, a novel species, Paenibacillus arcticus sp. nov., is proposed. The type strain is MME2_R6T (=JCM 30981T=PAMC 28731T).

CKD-506: A novel HDAC6-selective inhibitor that exerts therapeutic effects in a rodent model of multiple sclerosis.

Despite advances in therapeutic strategies for multiple sclerosis (MS), the therapy options remain limited with various adverse effects. Here, the therapeutic potential of CKD-506, a novel HDAC6-selective inhibitor, against MS was evaluated in mice with myelin oligodendrocyte glycoprotein35-55 (MOG35-55)-induced experimental autoimmune encephalitis (EAE) under various treatment regimens. CKD-506 exerted prophylactic and therapeutic effects by regulating peripheral immune responses and maintaining blood-brain barrier (BBB) integrity. In MOG35-55-re-stimulated splenocytes, CKD-506 decreased proliferation and downregulated the expression of IFN-γ and IL-17A. CKD-506 downregulated the levels of pro-inflammatory cytokines in the blood of EAE mice. Additionally, CKD-506 decreased the leakage of intravenously administered Evans blue into the spinal cord; CD4+ T cells and CD4-CD11b+CD45+ macrophage/microglia in the spinal cord was also decreased. Moreover, CKD-506 exhibited therapeutic efficacy against MS, even when drug administration was discontinued from day 15 post-EAE induction. Disease exacerbation was not observed when fingolimod was changed to CKD-506 from day 15 post-EAE induction. CKD-506 alleviated depression-like behavior at the pre-symptomatic stage of EAE. In conclusion, CKD-506 exerts therapeutic effects by regulating T cell- and macrophage-mediated peripheral immune responses and strengthening BBB integrity. Our results suggest that CKD-506 is a potential therapeutic agent for MS.

Deep learning method for comet segmentation and comet assay image analysis.

Comet assay is a widely used method, especially in the field of genotoxicity, to quantify and measure DNA damage visually at the level of individual cells with high sensitivity and efficiency. Generally, computer programs are used to analyze comet assay output images following two main steps. First, each comet region must be located and segmented, and next, it is scored using common metrics (e.g., tail length and tail moment). Currently, most studies on comet assay image analysis have adopted hand-crafted features rather than the recent and effective deep learning (DL) methods. In this paper, however, we propose a DL-based baseline method, called DeepComet, for comet segmentation. Furthermore, we created a trainable and testable comet assay image dataset that contains 1037 comet assay images with 8271 manually annotated comet objects. From the comet segmentation test results with the proposed dataset, the DeepComet achieves high average precision (AP), which is an essential metric in image segmentation and detection tasks. A comparative analysis was performed between the DeepComet and the state-of-the-arts automatic comet segmentation programs on the dataset. Besides, we found that the DeepComet records high correlations with a commercial comet analysis tool, which suggests that the DeepComet is suitable for practical application.

Enhanced Production of Gamma-Aminobutyric Acid by Optimizing Culture Conditions of Lactobacillus brevis HYE1 Isolated from Kimchi, a Korean Fermented Food.

This study evaluated the effects of culture conditions, including carbon and nitrogen sources, L-monosodium glutamate (MSG), and initial pH, on gamma-aminobutyric acid (GABA) production by Lactobacillus brevis HYE1 isolated from kimchi, a Korean traditional fermented food. L. brevis HYE1 was screened by the production analysis of GABA and genetic analysis of the glutamate decarboxylase gene, resulting in 14.64 mM GABA after 48 h of cultivation in MRS medium containing 1% (w/v) MSG. In order to increase GABA production by L. brevis HYE1, the effects of carbon and nitrogen sources on GABA production were preliminarily investigated via one-factor-at-a-time optimization strategy. As the results, 2% maltose and 3% tryptone were determined to produce 17.93 mM GABA in modified MRS medium with 1% (w/v) MSG. In addition, the optimal MSG concentration and initial pH were determined to be 1% and 5.0, respectively, resulting in production of 18.97 mM GABA. Thereafter, response surface methodology (RSM) was applied to determine the optimal conditions of the above four factors. The results indicate that pH was the most significant factor for GABA production. The optimal culture conditions for maximum GABA production were also determined to be 2.14% (w/v) maltose, 4.01% (w/v) tryptone, 2.38% (w/v) MSG, and an initial pH of 4.74. In these conditions, GABA production by L. brevis HYE1 was predicted to be 21.44 mM using the RSM model. The experiment was performed under these optimized conditions, resulting in GABA production of 18.76 mM. These results show that the predicted and experimental values of GABA production are in good agreement.