Biology subjects

Pillot, B.

Publications and source records attributed to Pillot, B..

3 recordsLinked to original sources

bioRxiv2025

N-acetyl-phenylalanine induces hepatic steatosis in MASLD by disrupting ER-mitochondria calcium coupling and mitochondrial lipid oxidation

Background & AimsThe gut-liver axis and hepatic ER-mitochondria miscommunication (at contact sites called MAMs) are involved in the development of metabolic dysfunction-associated steatotic liver disease (MASLD). We investigated the role of circulating aromatic amino acids (AAA) derived from phenylalanine and tyrosine in MASLD potentially through MAM alterations. MethodsWe analyzed AAA metabolomic profiles in individuals with and without MASLD and validated findings in a biopsy-proven cohort. The pro-steatogenic effect of MASLD-associated AAAs was validated in vitro using lipid labeling, MAM structural/functional assays, and palmitate-induced respiration. In vivo effects were tested in mice fed with candidate AAAs, and MAM involvement was confirmed by expressing a specific organelle linker in vitro and in vivo. ResultsN-acetyl-phenylalanine (NAPA) was strongly associated with hepatic steatosis and correlated with specific gut microbes. In vitro, NAPA promoted lipid accumulation by impairing ER-mitochondria calcium exchange via a LAT1-dependent electrogenic mechanism, reducing mitochondrial lipid oxidation. Chronic NAPA administration in mice induced steatosis and MAM disruption. Notably, enhancing ER-mitochondria contacts with an organelle linker prevented NAPA-induced steatosis in vitro and in vivo. Additionally, other phenylalanine- and tyrosine-derived AAAs reproduced NAPAs effects, suggesting a class-dependent mechanism. ConclusionNAPA emerges as a MASLD-promoting metabolite, contributing to hepatic steatosis by disrupting ER-mitochondria calcium coupling and mitochondrial lipid oxidation. Lay SummaryThe gut-liver axis is a key component of the development of MASLD, and circulating gut-derived metabolites, notably AAAs derived from phenylalanine and tyrosine metabolism, have been associated with MASLD. However, the specific causal mechanisms of these AAA metabolites in MASLD development remain unexplored. Here, we identified NAPA, a gut microbiome linked metabolite elevated in MASLD patients, as a causal driver of hepatic steatosis both in vitro and in vivo. Mechanistically, NAPA alters ER-mitochondria calcium coupling leading to reduced mitochondrial lipid oxidation, highlighting a new mechanism with potential therapeutic implications. HIGHLIGHTS- Circulating NAPA levels are increased in MASLD patients and correlate with hepatic steatosis. - NAPA levels result from a complex host-microbiota interplay - NAPA induces lipid accumulation by dampening ER-mitochondria calcium coupling and mitochondrial lipid oxidation. - NAPA disrupts MAMs by a LAT1-mediated electrogenic mechanism. - Other Phe- and Tyr-mediated metabolites have the same pro-steatogenic effect than NAPA pointing to a class-dependent effect.

pathology↗

bioRxiv2024

MorphoCellSorter: An Andrews plot-based sorting approach to rank microglia according to their morphological features

Microglia exhibit diverse morphologies reflecting environmental conditions, maturity or functional states. Thus, morphological characterization provides important information to understand microglial roles and functions. Most recent morphological analysis relies on classifying cells based on morphological parameters. However, this classification may lack biological relevance, as microglial morphologies represent a continuum rather than distinct, separate groups, and do not correspond to mathematically defined, clusters irrelevant of microglial cells function. Instead, we propose a new open-source tool, MorphoCellSorter, which assesses microglial morphology by automatically computing morphological criteria, using principal component analysis and Andrews plots to rank cells. MorphoCellSorter properly ranked cells from various microglia datasets in mice and rats of different age, from in vivo, in vitro and ex vivo models, that were acquired using diverse imaging techniques. This approach allowed for the discrimination of cell populations in various pathophysiological conditions. Finally, MorphoCellSorter offers a versatile, easy and ready-to-use method to evaluate microglial morphological diversity that could easily be generalized to standardize practices across laboratories.

neuroscience↗

bioRxiv2023

Oxidation-reduction imaging of myoglobin unveils two-phase oxidation in the reperfused myocardium.

Myocardial infarction (MI) is a serious cardiovascular problem that causes myocardial injury due to blood flow obstruction to a specific myocardial area. Under ischemic-reperfusion settings, a burst of reactive oxygen species is generated, leading to redox imbalance that could be attributed to several molecules, including myoglobin. Myoglobin is dynamic and exhibits various oxidation-reduction states that have been a subject of attention in the food industry, specifically for meat consumers. However, rarely if ever, have the myoglobin optical properties been used to understand the pathology of MI. In the current study, we develop a novel imaging pipeline that integrates tissue clearing, confocal and light sheet fluorescence microscopy, combined with imaging analysis, and processing tools to investigate and characterize the oxidation-reduction states of myoglobin in the ischemic area of the myocardium post-MI. Using spectral imaging, we have characterized the endogenous fluorescence of the myocardium and demonstrated that it aligns with the spectral profile of myoglobin. Under ischemia-reperfusion experimental settings, we report that the infarcted myocardium spectral signature is similar to that of oxidized myoglobin signal that peaks 3 hours post-reperfusion and decreases with cardioprotection. These results were correlated with MI measurements by Late Gadolinium Enhancement MRI. In conclusion, this seminal work suggests that the redox state of myoglobin can be used as a promising imaging biomarker for characterizing and estimating the size of the MI during early phases of reperfusion.

pathology↗