Biology subjects

Krasilnikov, M.

Publications and source records attributed to Krasilnikov, M..

3 recordsLinked to original sources

bioRxiv2023

Group 2 innate lymphoid cells constrain type 3/17 lymphocytes in shared stromal niches to restrict liver fibrosis

Group 2 innate lymphoid cells (ILC2s) cooperate with adaptive Th2 cells as key organizers of tissue type 2 immune responses, while a spectrum of innate and adaptive lymphocytes coordinate early type 3/17 immunity. Both type 2 and type 3/17 lymphocyte associated cytokines are linked to tissue fibrosis, but how their dynamic and spatial topographies may direct beneficial or pathologic organ remodelling is unclear. Here we used volumetric imaging in models of liver fibrosis, finding accumulation of periportal and fibrotic tract IL-5+ lymphocytes, predominantly ILC2s, in close proximity to expanded type 3/17 lymphocytes and IL-33high niche fibroblasts. Ablation of IL-5+ lymphocytes worsened carbon tetrachloride-and bile duct ligation-induced liver fibrosis with increased niche IL-17A+ type 3/17 lymphocytes, predominantly {gamma}{delta} T cells. In contrast, concurrent ablation of IL-5+ and IL-17A+ lymphocytes reduced this progressive liver fibrosis, suggesting a cross-regulation of type 2 and type 3 lymphocytes at specialized fibroblast niches that tunes hepatic fibrosis.

immunology↗

bioRxiv2022

Development of a dual fluorescent reporter system in Clostridioides difficile reveals a division of labor between virulence and transmission gene expression

The bacterial pathogen Clostridioides difficile causes gastroenteritis through its production of toxins and transmits disease through its production of resistant spores. Toxin and spore production are energy-expensive processes that are regulated by multiple transcription factors in response to many nutritional inputs. While toxin and sporulation genes are both heterogeneously expressed in only a subset of C. difficile cells, the relationship between these two sub-populations remains unclear. To address whether C. difficile coordinates the generation of these sub-populations, we developed a dual transcriptional reporter system that allows toxin and sporulation gene expression to be simultaneously visualized at the single-cell level using chromosomally-encoded mScarlet and mNeonGreen fluorescent transcriptional reporters. We then adapted an automated image analysis pipeline to quantify toxin and sporulation gene expression in thousands of individual cells in different media conditions and genetic backgrounds. These analyses revealed that toxin and sporulation gene expression rarely overlap during growth on agar plates, but broth culture increases this overlap in a manner dependent on the multifunctional RstA transcriptional regulator. Our results suggest that certain growth conditions promote a "division of labor" between transmission and virulence gene expression, highlighting how these subpopulations are influenced by environmental inputs. Given that recent work has revealed population-wide heterogeneity for numerous cellular processes in C. difficile, we anticipate that our dual reporter system will be broadly useful for determining the overlap in these subpopulations. IMPORTANCEClostridioides difficile is an important nosocomial pathogen that causes severe diarrhea by producing toxins and is transmitted by producing spores. While both processes are crucial for C. difficile disease, only a subset of cells express toxins and/or undergo sporulation. Whether C. difficile coordinates the relationship between these energy-expensive processes remains unknown. We developed a dual fluorescent reporter system coupled with an automated image analysis pipeline to rapidly characterize expression two genes of interest across thousands of bacterial cells. Using this reporter system, we discovered that toxin and sporulation gene expression appear to undergo a "division of labor" in certain growth conditions, particularly during growth on agar plates. Since C. difficile specializes into subpopulations for numerous vital cellular processes, this novel dual reporter system will enable future studies aimed at understanding how C. difficile coordinates various subpopulations throughout its infectious disease cycle.

microbiology↗

bioRxiv2020

Sentinel p16INK4a+ cells in the basement membrane form a reparative niche in the lung

Senescent cells are recognized drivers of aging-related decline in organ function, but deciphering the biology of senescence in vivo has been hindered by the paucity of tools to track and isolate senescent cells in tissues1-4. Deleting senescent cells from transgenic murine models have demonstrated therapeutic benefits in numerous age-related diseases5-11, but the identity, behavior, and function of the senescent cells deleted in vivo remain elusive. We engineered an ultra-sensitive reporter of p16INK4a, a biomarker of senescence12, to isolate and track p16INK4a+ cells in vivo. Surprisingly, p16INK4a+ mesenchymal cells appear in the basement membrane adjacent to epithelial progenitors in the lung shortly after birth, and these cells demonstrate senescent characteristics in vivo and ex vivo. Transcriptomic analysis of p16INK4a+ mesenchymal cells from non-aged lungs demonstrates a transition to a secretory phenotype upon airway epithelial injury. Heterotypic 3D organoid assays show that injured p16INK4a+ mesenchymal cells enhance epithelial progenitor proliferation, and we identified EREG as a novel airway progenitor mitogen produced by the secretory p16INK4a+ mesenchymal cells. Mesenchymal-specific deletion of the p16INK4a gene abrogates features of senescence in vivo, but also attenuates normal epithelial repair. Thus, p16INK4a+ mesenchymal cells can act as sentinels for the airway epithelial stem cell niche, poised to transition to a senescence-associated secretory phenotype to support barrier repair. Our data identify possible cellular targets in vivo for a rapidly growing list of senolytic therapies, but also raises important questions about the hidden cost of targeting senescent cells present in normal organs.

cell biology↗