Modeling and Simulation as a Tool to Assess Voriconazole Exposure in the Central Nervous System

The molecular mechanisms by which the NLRP3 inflammasome regulates blood-brain barrier permeability following cryptococcal meningitis

Objective

To investigate the mechanism underlying the regulation of blood-brain barrier permeability changes during cryptococcal meningitis by NLRP3 and Vimentin.

Methods

Sprague-Dawley rats were treated with WT Cryptococcus neoformans (Cn) or CPS1-/- Cn. Neuronal apoptosis was assessed using TUNEL staining, and pathological changes were observed using electron microscopy and HE staining. The expressions of NLRP3, Vimentin, and NF-κB in the cerebral cortex and human brain microvascular endothelial cells (HBMECs) were examined through Western blot and qRT-PCR. siNLRP3 and siVimentin were separately transfected into HBMECs, the expressions of specific factors were assessed. NF-κB and Vimentin levels were detected through immunofluorescence, apoptosis was measured using flow cytometry, and changes in the optical density (OD) of HRP were determined using ELISA.

Results

The expressions of NLRP3, Vimentin, and NF-κB were upregulated following intervention with WT Cn in vivo and in vitro. Electron microscopy revealed loose nuclear membranes in neurons and increased apoptosis in the cerebral cortex and hippocampus induced by WT Cn, accompanied by a reduction in the OD of HRP in vitro. siNLRP3 decreased the expressions of Vimentin, nuclear NF-κB, and β-Tubulin in HBMECs, while siVimentin downregulated total NLRP3 and nuclear NF-κB levels. Both siNLRP3 and siVimentin reduced cell apoptosis after WT Cn infection. HBMECs displayed a reduced monolayer permeability to HRP and improved cell structure arrangement.

Conclusion

Vimentin and the NLRP3 inflammasome are both implicated in the pathological process of cryptococcal meningitis. An interaction between Vimentin and the NLRP3 inflammasome is evident, likely mediated through the NF-κB signaling pathway.

Preclinical Models for Cryptococcosis of the CNS and Their Characterization Using In Vivo Imaging Techniques

Infections caused by Cryptococcus neoformans and Cryptococcus gattii remain a challenge to our healthcare systems as they are still difficult to treat. In order to improve treatment success, in particular for infections that have disseminated to the central nervous system, a better understanding of the disease is needed, addressing questions like how it evolves from a pulmonary to a brain disease and how novel treatment approaches can be developed and validated. This requires not only clinical research and research on the microorganisms in a laboratory environment but also preclinical models in order to study cryptococci in the host. We provide an overview of available preclinical models, with particular emphasis on models of cryptococcosis in rodents. In order to further improve the characterization of rodent models, in particular the dynamic aspects of disease manifestation, development, and ultimate treatment, preclinical in vivo imaging methods are increasingly used, mainly in research for oncological, neurological, and cardiac diseases. In vivo imaging applications for fungal infections are rather sparse. A second aspect of this review is how research on models of cryptococcosis can benefit from in vivo imaging methods that not only provide information on morphology and tissue structure but also on function, metabolism, and cellular properties in a non-invasive way.