Biology subjects

Udayasuryan, B.

Publications and source records attributed to Udayasuryan, B..

5 recordsLinked to original sources

bioRxiv2025

Outer Membrane Vesicles Hijack TIM-1 for Cellular Uptake

Outer membrane vesicles (OMVs) are nanoscale proteoliposomes shed by Gram-negative bacteria that mediate host-pathogen interactions and hold promise as platforms for vaccines and targeted drug delivery. Despite their biological and translational significance, the cellular mechanisms governing OMV entry into host cells remain poorly understood. Here, we demonstrate that E. coli OMVs are internalized by epithelial cells via clathrin-mediated, receptor-dependent endocytosis. Using a high-throughput screen of over 1,500 human single-pass transmembrane proteins, we identify T-cell immunoglobulin and mucin-domain 1 (TIM-1) as a strong OMV-binding receptor. Functional validation revealed that TIM-1 overexpression markedly increased OMV uptake, whereas TIM-1 knockout and antibody-mediated blockade significantly impaired internalization across multiple cell lines. Mechanistic studies demonstrate that TIM-1 binds to lipopolysaccharide (LPS) on the OMV surface via its known phosphatidylserine-binding domain. Uptake of OMVs by TIM-1 triggers proinflammatory cytokine production which can be reduced by preventing this interaction. Additionally, OMVs from multiple bacterial species hijack TIM-1 for entry, making it an intriguing antivirulence strategy. Our findings establish TIM-1 as a critical host receptor mediating OMV uptake and provide a novel approach to modulate vesicle-driven pathogenesis and enhance OMV-based therapies.

microbiology↗

bioRxiv2025

A microbiota-derived bile acid modulates biofilm formation by the probiotic strain Escherichia coli Nissle 1917

Bacteria that colonize the human gut must withstand a variety of stressors, including detergent-like compounds known as bile acids. Here, we investigated how bile acids found in the human cecum and colon impact the behavior of the probiotic strain Escherichia coli Nissle 1917 (EcN). We found that lithocholic acid (LCA), which is a microbiota-derived secondary bile acid, promotes the formation of a distinctive surface-coating biofilm by EcN, including on an organoid-derived model of the human colonic epithelium. Mechanistic investigations revealed that LCA upregulates the production of several components of flagella, which are essential for LCA-induced biofilm formation and form part of the biofilm matrix. Furthermore, LCA-induced biofilm formation helps EcN compete against certain pathogenic strains. Taken together, our findings shed light on how an abundant colonic metabolite influences the behavior of a clinically-proven probiotic strain, triggering the formation of biofilms that may contribute to pathogen suppression.

microbiology↗

bioRxiv2021

Fusobacterium nucleatum infection induces pancreatic cancer cell proliferation and migration through regulation of host cytokine signaling

Pancreatic ductal adenocarcinoma (PDAC) harbors a complex tumor microbiome that has been implicated in cancer progression and resistance to chemotherapy. Recent clinical investigations uncovered a correlation between high loads of intratumor Fusobacterium nucleatum and decreased patient survival. Here we show that healthy and cancerous pancreatic cell lines harboring intracellular F. nucleatum secrete increased levels of cancer-associated cytokines including GM-CSF, CXCL1, IL-8, and MIP-3. We report that GM-CSF (granulocyte-macrophage colony stimulating factor) secretion directly increases the proliferation and migration of pancreatic cancer cells via an autocrine mechanism, notably in the absence of immune cell participation. Furthermore, we show that non-cancerous pancreatic epithelial cells do not exhibit increased proliferation or migration in response to these cytokines, but nevertheless, their secreted cytokines stimulate these responses in cancerous cell lines through paracrine signaling. Our results provide evidence that intratumor F. nucleatum in the pancreas elicits an infection-specific cytokine secretion profile from both normal and cancerous cells that adversely contributes to cancer progression through autocrine and paracrine mechanisms. Therefore, these results support the importance of investigating the contributions of both microbiome and host driven processes in pancreatic cancer to guide future therapeutic interventions.

cancer biology↗

bioRxiv2020

Fusobacterium nucleatum host cell binding and invasion induces IL-8 and CXCL1 secretion that drives colorectal cancer cell migration

Fusobacterium nucleatum is implicated in the acceleration of colorectal cancer (CRC), yet the mechanisms by which this bacterium modulates the tumor microenvironment remain understudied. Here we show that binding and cellular invasion of CRC cells selectively induces the secretion of the pro-inflammatory and metastatic cytokines IL-8 and CXCL1, which we then show induces robust migration of HCT116 cancer cells. Next, we demonstrate that cytokine signaling by cancer cells is largely driven by invasion coordinated by the surface adhesin Fap2. By contrast, we show that F. nucleatum induced secretion of CCL3, CXCL2, and TNF cytokines from neutrophils and macrophages is Fap2 independent. Finally, we show that inhibiting F. nucleatum host-cell binding and entry using galactose sugars, neutralizing membrane antibodies, and deletion of the fap2 gene, lead to attenuated cytokine secretion and cellular migration. As elevated IL-8 and CXCL1 levels in cancer have been associated with increased metastatic potential and cell seeding, poor prognosis, and enhanced recruitment of tumor-associated macrophages and fibroblasts within tumor microenvironments, these data show that F. nucleatum directly and indirectly modulates immune and cancer cell signaling and migration. In conclusion, as viable F. nucleatum were previously shown to migrate within metastatic CRC cells, we propose that inhibition of host cell binding and invasion, potentially through vaccination or novel galactoside compounds, could be an effective strategy for reducing F. nucleatum-induced signaling that drives metastasis and cancer cell seeding.

cancer biology↗

bioRxiv2019

Reevaluating the Fusobacterium Virulence Factor Landscape

Fusobacterium are Gram-negative, anaerobic, opportunistic pathogens involved in multiple diseases, including the oral pathogen Fusobacterium nucleatum being linked to the progression and severity of colorectal cancer. The global identification of virulence factors in Fusobacterium has been greatly hindered by a lack of properly assembled and annotated genomes. Using newly completed genomes from nine strains and seven species of Fusobacterium, we report the identification and correction of virulence factors from the Type 5 secreted autotransporter and FadA protein families, with a focus on the genetically tractable strain F. nucleatum subsp. nucleatum ATCC 23726 and the classic typed strain F. nucleatum subsp. nucleatum ATCC 25586. Within the autotransporters, we employed protein sequence similarity networks to identify subsets of virulence factors, and show a clear differentiation between the prediction of outer membrane adhesins, serine proteases, and proteins with unknown function. These data have defined protein subsets within the Type 5a effectors that are present in predicted invasive strains but are broadly lacking in passively invading strains; a key phenotype associated with Fusobacterium virulence. However, our data shows that prior bioinformatic analysis that predicted species of Fusobacterium to be non-{inverted exclamation}nvasive can indeed invade human cells, and that pure phylogenetic analysis to determine the virulence within this bacterial genus should be used cautiously and subsequently paired with experiments to validate these hypotheses. In addition, we provide data that show a complex interplay between autotransporters, MORN2 domain containing proteins, and FadA adhesins that we hypothesize synergistically contribute to host cell interactions and invasion. In summary, we report that accurate open reading frame annotations using complete Fusobacterium genomes, in combination with experimental validation of invasion, redefines the repertoire of virulence factors that could be contributing to the species specific pathology of multiple Fusobacterium induced infections and diseases. IMPORTANCEFusobacterium are emerging pathogens that contribute to the progression and severity of multiple mammalian and human infectious diseases, including colorectal cancer. Despite a validated connection with disease, a limited number of proteins have been characterized that define a direct molecular mechanism for pathogenesis in a diverse range of host tissue infections. We report a comprehensive examination of virulence associated protein families in multiple Fusobacterium species, and show that complete genomes facilitate the correction and identification of multiple, large Type 5a secreted autotransporter genes in previously misannotated or fragmented genomes. In addition, we use protein sequence similarity networks and human cell invasion experiments to show that previously predicted non-invasive strains can indeed enter human cells, and that this is likely due to the expansion of specific virulence proteins that drive F. nucleatum infections and disease.

microbiology↗