Biology subjects

Watanabe, F.

Publications and source records attributed to Watanabe, F..

3 recordsLinked to original sources

bioRxiv2025

Concentration-dependent suppression of macrolide resistance in Mycobacterium avium by combination therapy: an improved in vitro time-kill assay and PK/PD modelling study

ObjectivesMacrolides are key drugs in the treatment for Mycobacterium avium pulmonary disease, and combination chemotherapy is essential to preventing macrolide resistance. However, the concentrations of concomitant agents required to suppress resistance emergence remain undefined. This study aimed to quantify the concentration-dependent effects of companion drugs on macrolide resistance using an improved time-kill assay and pharmacokinetic/pharmacodynamic (PK/PD) modelling approach. MethodsTime-kill assays were performed on M. avium ATCC 700898 using azithromycin alone or in combination with ethambutol, rifampicin, amikacin, or clofazimine. Total and resistant bacterial populations were quantified over 28 days. A pharmacodynamic (PD) model describing the dynamics of susceptible and resistant subpopulations was linked to a pharmacokinetic (PK) model incorporating alveolar macrophage concentrations to simulate resistance and bactericidal rates under various dosing regimens. ResultsMacrolide resistance most frequently emerged at 2-4x the minimum inhibitory concentration (MIC) of azithromycin, whereas resistance was less frequent at 8-16x MIC or sub-MIC levels. The addition of companion drugs suppressed resistance emergence even at sub-MIC levels. PK/PD simulations demonstrated that standard-dose ethambutol effectively prevented macrolide resistance, whereas rifampicin provided minimal protection. More frequent dosing schedules enhanced resistance suppression compared with once-daily regimens. ConclusionThis study defines the concentration-dependent contributions of concomitant agents to macrolide resistance suppression in M. avium and establishes a quantitative PK/PD framework for evaluating resistance emergence. These findings provide mechanistic insights to support the optimization of combination dosing strategies for M. avium pulmonary disease.

pharmacology and toxicology↗

bioRxiv2022

Modeling of Aryl Hydrocarbon Receptor Pathway Intrinsic Immunometabolic Role using Glioblastoma Stem Cells and Patient-Derived Organoids

The intrinsic genetic program of glioblastoma (GBM) stem cells is critical for tumor evolution and recurrence. We recently identified intrinsic phenotypes and immune-like genetic programs of GBM organoids (GBMO)1 from patient derived glioblastoma stem cells (GSCs), replicating genomic, metabolic, and cellular aspects of GBM in vivo. Aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor, is a key regulator of infiltrating immune cells in gliomas2, 3 and associated with poor prognosis, but its role in GSC biology is unknown2. Here, we show that AHR is a patient-specific regulator of the glioma intrinsic gene program in GSCs and GSC-derived GBMO that are enriched for AHR. We find that AHR is required for GSC self-renewal, GBMO expansion, radial glia-like cell proliferation, and expression of immune mediators seen in the mesenchymal subtype. CRISPR-Cas9 genetic ablation and pharmacological inhibition revealed that AHR regulates genes linked to intrinsic immunity, proliferation, and migration in GBMO. Genomic analysis of GBMO treated with AHR inhibitors identified expression signatures and candidate markers associated with survival of gliomas. Our work defines the glioma intrinsic function of AHR in a model of early GBM formation, offering a rationale for clinical exploration of a potential two-hit target of both GBM cells and infiltrating immune cells in patients with GBM expressing high levels of AHR.

cancer biology↗

bioRxiv2021

Patient-Derived Organoids Recapitulate Intrinsic Immune Landscapes and Progenitor Populations of Glioblastoma.

Glioblastoma stem cells (GSCs) are highly self-renewing, resistant to therapy, and are able to form lethal tumors1, 2. Tumor organoids have been developed to study tumor evolution1-4, and while GSCs can form organoids for glioblastoma multiforme, our understanding of their intrinsic immune, metabolic, genetic, and molecular programs is limited. To address this, we deeply characterized GSC-derived GBM organoids using a modified protocol (GBMOsm) from several patient-derived GSCs and found they develop into complex 3D tissues with unique self-organization, cancerous metabolic states, and burdensome genetic landscapes. We discovered that GBMOsc recapitulate the presence of two important cell populations thought to drive GBM progression, SATB2+ and HOPX+ progenitors. Despite being devoid of immune cells, transcriptomic analysis across GBMOsc revealed an immune-like molecular program, enriched in cytokine, antigen presentation and processing, T-cell receptor inhibitors, and interferon genes. We determined that SATB2+ and HOPX+ populations contribute to this immune and interferon landscape in GBM in vivo and GBMOsm. Our work deepens our understanding of the intrinsic molecular and cellular architecture of GSC-derived GBMO and defines a novel GBMOsc intrinsic immune-like program.

neuroscience↗