Biology subjects

Giurleo, A.

Publications and source records attributed to Giurleo, A..

3 recordsLinked to original sources

bioRxiv2026

Discovery of a hydrolysis operon in Lachnospiraceae provides a genetic basis to understanding castalagin metabolism by the human microbiome in a clinical study.

Gut microbes metabolize the ellagitannin castalagin to ellagic acid and urolithins, a process associated with health effects for the host. Despite the use of the castalagin-rich camu camu extracts in clinical trials, the genes and taxa responsible for castalagin hydrolysis remain elusive. We used multi-omics to discover a castalagin associated hydrolase (cah) operon sparsely distributed in Lachnospiraceae. Analysis of fecal samples from a camu camu supplementation clinical trial demonstrates functional redundancy with prevalence of cah and other ellagic acid metabolism genes in different taxa explaining the prevalence of metabolites. Employing genome mining strategies, we discovered and validated ellagitannin metabolism genes in uncharacterized and uncultured species. We further identified flavogallonic acid as a prevalent metabolite of castalagin in human fecal samples. Collectively, this work provides a genetic basis for castalagin metabolism to urolithins and flavogallonic acid end-metabolites and sets the stage to study the role of metabolism in clinical trials.

microbiology↗

bioRxiv2025

The presence and induction of regioselective dehydroxylases dictate urolithin metabolism by Enterocloster species

Urolithins are a class of bioactive metabolites derived from the metabolism of dietary ellagitannins by the human gut microbiota. In the gut, urolithins are dehydroxylated regioselectively based on microbiota composition and activity. A single 9-hydroxy urolithin dehydroxylase (ucd) operon in gut resident Enterocloster species has been described to date; however, most enzymes in the urolithin metabolic pathway remain uncharacterized. Here, we investigate urolithin cross-feeding between members of the gut microbiota and discover a novel urolithin dehydroxylase in a subset of Enterocloster species. We show that urolithin intermediates, released by gut resident Gordonibacter species during ellagic acid metabolism, are dehydroxylated at both the 9- and 10-positions by E. asparagiformis, E. citroniae, and E. pacaense, but not E. bolteae. Using untargeted proteomics, we uncover a 10-hydroxy urolithin dehydroxylase operon, termed uxd, responsible for these species-specific differences in urolithin metabolism. By inducing uxd expression with diverse urolithins, we show that 9-hydroxy urolithins are required for uxd transcription and 10-position dehydroxylation. Collectively, this study reveals some of the genes, proteins, and substrate features underlying differences in urolithin metabolism by the human gut microbiota.

microbiology↗

bioRxiv2024

The functional and pathogenic consequences of fibrinogen on human oligodendroglia

Fibrinogen is a blood-derived protein involved in coagulation, and can make its way into the central nervous system (CNS) following breakdown of the blood-brain barrier. This molecule has been implicated in multiple sclerosis (MS), a disease marked by inflammation and demyelination in the CNS, as well as other neurological disorders. However, the effect of this molecule has not been studied on human myelinating cells. This study examines how fibrinogen influences human oligodendrocyte (OL) lineage cells at various stages of development. Using induced pluripotent stem cell-derived (iPSC) OL precursors and human primary OLs, we examined the effects of fibrinogen on cell differentiation, viability and myelination-related function. Here we show that fibrinogen induces an aberrant differentiation of early lineage OLs, by inhibiting their maturation and inducing an astrocytic phenotype, as seen in previous studies. On mature OLs, fibrinogen was found to promote myelination capacity as shown by ensheathment assays as well as on the RNA level. These effects were associated with the activation of BMP signalling, both in early and mature OLs. Transcriptomic analysis of human MS brain tissue shows similar pro-myelination changes in a subset of OLs, suggesting in vivo relevance. These findings indicate that fibrinogen has a lineage-dependent effect, where it may be inhibitory earlier in the lineage while promoting OL function in later stages. Understanding this dual role will provide insight into remyelination failure in MS and highlights the importance of timing and target in future therapeutic strategies. Significance StatementIn multiple sclerosis (MS), the blood protein fibrinogen leaks into the brain and has been shown to interfere with myelin repair. This study demonstrates that fibrinogen has opposite effects on human oligodendrocyte-lineage cells depending on their stage of maturation. While it blocks the differentiation of early-stage cells, it enhances the functional capacity of mature oligodendrocytes. These findings help explain why remyelination may fail in MS and suggest that fibrinogen could both hinder and support repair, depending on the cell context. This dual role has important implications for developing stage-specific therapies for MS.

neuroscience↗