Abbey, D. | Search bioRxiv

bioRxiv2024

Blood cultures at baseline and during persistent candidemia contain populations of genetically diverse Candida albicans strains that may differ in echinocandin tolerance and virulence

It is unknown whether within-patient Candida albicans diversity is common during bloodstream infections (BSIs). We determined whole genome sequences of 10 C. albicans strains from blood cultures (BCs) in each of 4 patients. BCs in 3 patients contained mixed populations of strains that differed by large-scale genetic variants, including chromosome (Chr) 5 or 7 aneuploidy (n=2) and Chr1 loss of heterozygosity (n=1). Chr7 trisomy (Tri7) strains from patient MN were attenuated for hyphal and biofilm formation in vitro compared to euploid strains, due at least in part to NRG1 over-expression. Nevertheless, representative Tri7 strain M1 underwent filamentation during disseminated candidiasis (DC) in mice. M1 was more fit than euploid strain M2 during DC and mouse gastrointestinal colonization, and in blood ex vivo. M1 and M2 exhibited identical echinocandin minimum inhibitory concentrations, but M2 was more tolerant to micafungin in vitro. Furthermore, M2 was more competitive with M1 in mouse kidneys following micafungin treatment than it was in absence of micafungin. Tri7 strains represented 74% of patient MNs baseline BC population, but after 1d and 3d of echinocandin treatment, euploid strains were 93% and 98% of the BC population, respectively. Findings suggest that echinocandin tolerant, euploid strains were a subpopulation to more virulent Tri7 strains at baseline and then were selected upon echinocandin exposure. In conclusion, BCs in at least some patients are comprised of diverse C. albicans populations not recognized by the clinical lab, rather than single strains. Clinical relevance of C. albicans diversity and antifungal tolerance merits further investigation.

microbiology↗

bioRxiv2019

NASH patient liver derived organoids exhibit patient specific NASH phenotypes and drug responses.

To determine if patient liver derived organoids can in principle be a useful experimental model for non alcoholic staetohepatitis (NASH), we derived to our knowledge for the first time bipotent ductal organoids from endstage NASH patient livers, and for comparison from normal donor livers. We found that all tested NASH liver derived organoids exhibited a profound failure to dedifferentiate from the hepatic state back to the biliary state, consistent with the known poor regenerative capacity of NASH livers. Indeed, RNAseq on all tested NASH organoid populations confirmed down regulation of multiple cell cycle pathways. NASH liver derived hepatically differentiated organoids can slowly expand as monolayers, significantly simplifying microscopic quantitation: The monolayers show variable, but overall significantly increased lipid droplet accumulation in response to free fatty acids. Transcriptome analysis of NASH organoids reveals strong upregulation of a wide variety of pro inflammatory pathways in a NASH patient specific manner. Surprisingly, NASH liver derived organoids are highly diverse not only regarding their cytochrome cytochrome p450 metabolism and inflammatory response, but also react differentially to known antisteatotic, anti inflammatory and antifibrotic drugs, raising the possibility of using NASH patient liver biopsy derived organoids for personalized drug screening and therapy.\n\nOne Sentence SummaryNASH patient liver derived organoids replicate NASH liver phenotypes in a patient specific manner and exhibit profound differences in their response to drugs that are currently used in NASH clinical trials.

cell biology↗