1. Implication of caspases during maedi-visna virus-induced apoptosis
S Delebassée, V Bellet, R Duval, C Bosgiraud J Gen Virol . 2002 Dec;83(Pt 12):3153-3161. doi: 10.1099/0022-1317-83-12-3153.
Maedi-visna virus (MVV) causes encephalitis, pneumonia and arthritis in sheep. In vitro, MVV infection and replication lead to strong cytopathic effects characterized by syncytia formation and subsequent cellular lysis. It was demonstrated previously that MVV infection in vitro induces cell death of sheep choroid plexus cells (SCPC) by a mechanism that can be associated with apoptotic cell death. Here, the relative implication of several caspases during acute infection with MVV is investigated by employing diverse in vitro and in situ strategies. It was demonstrated using specific pairs of caspase substrates and inhibitors that, during in vitro infection of SCPC by MVV, the two major pathways of caspase activation (i.e. intrinsic and extrinsic pathways) were stimulated: significant caspase-9 and -8 activities, as well as caspase-3 activity, were detected. To study the role of caspases during MVV infection in vitro, specific, cell-permeable, caspase inhibitors were used. First, these results showed that both z-DEVD-FMK (a potent inhibitor of caspase-3-like activities) and z-VAD-FMK (a broad spectrum caspase inhibitor) inhibit caspase-9, -8 and -3 activities. Second, both irreversible caspase inhibitors, z-DEVD-FMK and z-VAD-FMK, delayed MVV-induced cellular lysis as well as virus growth. Third, during SCPC in vitro infection by MVV, cells were positively stained with FITC-VAD-FMK, a probe that specifically stains cells containing active caspases. In conclusion, these data suggest that MVV infection in vitro induces SCPC cell death by a mechanism that is strongly dependent on active caspases.
2. Antifungal Effects and Potential Mechanisms of Benserazide Hydrochloride Alone and in Combination with Fluconazole Against Candida albicans
Xueqi Chen, Shan Su, Jiyong Wu, Shujuan Sun, Jing Nie, Lei Sun Drug Des Devel Ther . 2021 Nov 16;15:4701-4711. doi: 10.2147/DDDT.S336667.
Purpose:The resistance ofC. albicansto traditional antifungal drugs brings a great challenge to clinical treatment. To overcome the resistance, developing antifungal agent sensitizers has attracted considerable attention. This study aimed to determine the anti-Candidaactivity of BEH alone or BEH-FLC combination and to explore the underlying mechanisms.Materials and methods:In vitro antifungal effects were performed by broth microdilution assay and XTT reduction assay. InfectedGalleria mellonellalarvae model was used to determine the antifungal effects in vivo. Probes Fluo-3/AM, FITC-VAD-FMK and rhodamine 6G were used to study the influence of BEH and FLC on intracellular calcium concentration, metacaspase activity and drug efflux ofC. albicans.Results:BEH alone exhibited obvious antifungal activities againstC. albicans. BEH plus FLC not only showed synergistic effects against planktonic cells and preformed biofilms within 8 h but also enhanced the antifungal activity in infectedG. mellonellalarvae. Mechanistic studies indicated that antifungal effects of drugs might be associated with the increasement of calcium concentration, activation of metacaspase activity to reduce virulence and anti-biofilms, but were not related to drug efflux.Conclusion:BEH alone or combined with FLC displayed potent antifungal activity both in vitro and in vivo, and the underlying mechanisms were related to reduced virulence factors.
3. Antifungal effects and potential mechanisms of lonidamine in combination with fluconazole against Candida albicans
Xueqi Chen, Shan Su, Yinping Shi, Shujuan Sun, Peng Wang, Yiman Li Expert Rev Anti Infect Ther . 2021 Jan;19(1):109-115. doi: 10.1080/14787210.2020.1811684.
Objectives:The resistance ofCandida albicans(C. albicans) to classical antifungals has been increasing significantly and poses great challenges to clinical treatment. The objective of this research is to evaluate whether the combination of lonidamine (LND) and fluconazole (FLC) have synergistic antifungal activity againstC. albicansand to explore the underlying synergistic mechanisms against FLC-resistantC. albicans.Methods:The antifungal effect on resistant planktonicC. albicansand preformed biofilms were performed by broth microdilution assay and XTT reduction assay. The influence on hyphal growth, cellular ROS level, metacaspase activity and drug transporters were investigated by morphogenesis observation, DCFH-DA, FITC-VAD-FMK and rhodamine6G assay, respectively.Results:LND in combination with FLC exhibited synergistic antifungal effects against resistant planktonicC. albicansand preformed biofilms ofC. albicansin the early stages (performed at 4 h and 8 h). The synergistic mechanisms associated with the inhibition of the hyphal growth and the activation of metacaspase, but were not related to mediate cellular ROS level or drug uptake and efflux in resistantC. albicans.Conclusion:LND combined with FLC exhibited synergistic antifungal activity against resistantC. albicans, and the synergistic mechanisms were related to anti-biofilms and reduce virulence factors.Expert opinion:The emergence of fluconazole-resistantCandida albicansstrains poses great challenges to clinical treatment. Drug combination of non-antifungals and fluconazole has attracted a lot of attention to overcomeCandida albicansdrug resistance.
