Chlamydial Infection-Dependent Synthesis of Sphingomyelin as a Novel Anti-Chlamydial Target of Ceramide Mimetic Compounds

The obligate intracellular bacterium Chlamydia trachomatis is the major causative agent of bacterial sexually transmitted diseases worldwide. In infected cells, the ceramide transport protein (CERT) is recruited to inclusions, where C. trachomatis replicates using host-synthesized ceramide. The ceramide is converted to sphingomyelin (SM) by a chlamydial infection-dependent SM synthesis (cidSM-synthesis) pathway, which occurs even in the absence of the SM synthases (SMS)-1 and -2 of host cells. The ceramide mimetic compound (1R,3S)-HPA-12 and the nonmimetic compound E16A, both of which are potent inhibitors of CERT, repressed the proliferation of C. trachomatis in HeLa cells. Unexpectedly, (1R,3R)-HPA-12, a ceramide mimetic compound that lacks CERT inhibitory activity, also exhibited potent anti-chlamydial activity. Using endogenous SMS-knockout mutant HeLa cells, we revealed that (1R,3R)-HPA-12 mildly inhibited cidSM-synthesis. In addition, LC-MS analysis revealed that (1R,3R)-HPA-12 is converted to a phosphocholine-conjugated metabolite in an infection-dependent manner. Imaging analysis with a fluorescent analog of ceramide suggested that cidSM-synthesis occurs in the bacterial bodies and/or inclusions. Collectively, these results suggested that (1R,3R)-HPA-12 exerts its anti-chlamydia activity not only as an inhibitor of cidSM-synthesis, but also via putative toxic effects of its phosphocholine adduct, which is most likely produced by the cidSM-synthesis route

Integrated education of gross anatomy and CT radiology for current advances in medicine

It is essential to learn human anatomy in 3D for advanced medicine. We designed such an education system by integrating anatomy dissection with diagnostic CT radiology. Cadavers were scanned by CT, and students consulted the postmortem CT images while dissecting the cadaver to gain a better understanding of 3D human anatomy and diagnostic radiology. Students used handheld DICOM viewers at the bench-side (OsiriX on iPod touch). Students had lectures and workshops on diagnostic radiology, and study assignments where they discussed findings in anatomy labs in comparison with CT radiology. This teaching method for gross anatomy was used from 2009, and yielded positive students’ perspectives, and significant improvements in radiology skills at clinical courses.This is the pre-peer reviewed version of the following article: Tohru Murakami, Yuki Tajika, Hitoshi Ueno, Sachiko Awata, Satoshi Hirasawa, Maki Sugimoto, Yoshihiko Kominato, Yoshito Tsushima, Keigo Endo, and Hiroshi Yorifuji. An integrated teaching method of gross anatomy and computed tomography radiology. Anat Sci Educ, 2014, which has been published in final form at http://onlinelibrary.wiley.com/ doi/10.1002/ase.1430/abstract

Natural ligand-nonmimetic inhibitors of the lipid-transfer protein CERT

Lipid transfer proteins mediate inter-organelle transport of membrane lipids at organelle contact sites in cells, playing fundamental roles in the lipidome and membrane biogenesis in eukaryotes. We previously developed a ceramide-mimetic compound as a potent inhibitor of the ceramide transport protein CERT. Here we develop CERT inhibitors with structures unrelated to ceramide. To this aim, we identify a seed compound with no ceramide-like structure but with the capability of forming a hydrogen-bonding network in the ceramide-binding START domain, by virtual screening of ~3 × 106 compounds. We also establish a surface plasmon resonance-based system to directly determine the affinity of compounds for the START domain. Then, we subject the seed compound to a series of in silico docking simulations, efficient chemical synthesis, affinity analysis, protein-ligand co-crystallography, and various in vivo assays. This strategy allows us to obtain ceramide-unrelated compounds that potently inhibited the function of CERT in human cultured cells

Intestinal Resident Yeast Candida glabrata Requires Cyb2p-Mediated Lactate Assimilation to Adapt in Mouse Intestine

The intestinal resident Candida glabrata opportunistically infects humans. However few genetic factors for adaptation in the intestine are identified in this fungus. Here we describe the C. glabrata CYB2 gene encoding lactate dehydrogenase as an adaptation factor for survival in the intestine. CYB2 was identified as a virulence factor by a silkworm infection study. To determine the function of CYB2, we analysed in vitro phenotypes of the mutant Δcyb2. The Δcyb2 mutant grew well in glucose medium under aerobic and anaerobic conditions, was not supersensitive to nitric oxide which has fungicidal-effect in phagocytes, and had normal levels of general virulence factors protease, lipase and adherence activities. A previous report suggested that Cyb2p is responsible for lactate assimilation. Additionally, it was speculated that lactate assimilation was required for Candida virulence because Candida must synthesize glucose via gluconeogenesis under glucose-limited conditions such as in the host. Indeed, the Δcyb2 mutant could not grow on lactate medium in which lactate is the sole carbon source in the absence of glucose, indicating that Cyb2p plays a role in lactate assimilation. We hypothesized that Cyb2p-mediated lactate assimilation is necessary for proliferation in the intestinal tract, as the intestine is rich in lactate produced by bacteria flora, but not glucose. The Δcyb2 mutant showed 100-fold decreased adaptation and few cells of Saccharomyces cerevisiae can adapt in mouse ceca. Interestingly, C. glabrata could assimilate lactate under hypoxic conditions, dependent on CYB2, but not yeast S. cerevisiae. Because accessible oxygen is limited in the intestine, the ability for lactate assimilation in hypoxic conditions may provide an advantage for a pathogenic yeast. From those results, we conclude that Cyb2p-mediated lactate assimilation is an intestinal adaptation factor of C. glabrata

Differences in Ocular Complications Between Candida albicans and Non-albicans Candida Infection Analyzed by Epidemiology and a Mouse Ocular Candidiasis Model

Objectives:Candida species are a major cause of hospital infections, including ocular candidiasis, but few studies have examined the propensities of specific species to invade the eye or the unique immunological responses induced. This study examined the frequency and characteristics of species-specific Candida eye infections by epidemiology and experiments using a mouse ocular candidiasis model.Methods: We reviewed medical records of candidemia patients from January 2012 to March 2017. We also evaluated ocular fungal burden, inflammatory cytokine and chemokine profiles, and inflammatory cell profiles in mice infected with Candida albicans, Candida glabrata, or Candida parapsilosis.Results: During the study period, 20 ocular candidiasis cases were diagnosed among 99 candidemia patients examined by ophthalmologists. Although C. parapsilosis was the most frequent candidemia pathogen, only C. albicans infection was significantly associated with ocular candidiasis by multivariate analysis. In mice, ocular fungal burden and inflammatory mediators were significantly higher during C. albicans infection, and histopathological analysis revealed invading C. albicans surrounded by inflammatory cells. Ocular neutrophil and inflammatory monocyte numbers were significantly greater during C. albicans infection.Conclusion:Candida albicans is strongly associated with ocular candidiasis due to greater capacity for invasion, induction of inflammatory mediators, and recruitment of neutrophils and inflammatory monocytes