Biology subjects

Zachos, N. C.

Publications and source records attributed to Zachos, N. C..

4 recordsLinked to original sources

bioRxiv2026

Candida albicans promotes self-adhesion and tumor cell progression of colorectal cancer cells.

Candida albicans, a benign commensal yeast in the healthy gut, is increasingly being recognized as a tumor-promoting component of the gut mycobiome that is linked to worse patient outcomes in colorectal cancer (CRC). Emerging evidence suggests that in the tumor microenvironment, C. albicans drives tumor progression in its pathogenic hyphal form with the secretion of its peptide toxin, candidalysin, enhancing tumor cell evolution. CRC cells differentially express transglutaminase 2 (TG2), which mediates covalent binding to C. albicans and can promote tumor adaptability and metastases. However, mechanistic insight into how C. albicans infection leads to CRC progression is incomplete. CRC lines that express high (SW480) and low (LoVo, HCT 116) TG2 were infected with C. albicans and examined for effects on epithelial to mesenchymal transition (EMT) and cell migration. Parallel studies were also conducted using a candidalysin-deficient C. albicans strain. C. albicans invasion stimulated TG2 activity that allowed covalent crosslinking of the hyphae adhesin, Hwp1, to SW480 cells in a candidalysin-dependent manner. Independent of TG2 expression, infection of SW480, LoVo, and HCT 116 cells induced EMT-like changes including downregulation of E-cadherin, altered N-glycosylation of N-cadherin, and variable Snail1 expression. Infection increased MGAT5 activity, which raised levels of branched {beta}(1-6) N-glycans. Infection promoted CRC cell motility that was blocked by pharmacological inhibition of MGAT5. Thus, C. albicans engages CRC cells through separable mechanisms: a candidalysin-TG2-Hwp1 axis that may stabilize fungal attachment in TG2-high tumor cells, and a TG2-independent program of epithelial plasticity, altered N-glycosylation and migration-associated behavior that requires validation in vivo.

microbiology↗

bioRxiv2021

Yersinia pseudotuberculosis YopE prevents uptake by M cells and instigates M cell extrusion in human ileal enteroid-derived monolayers.

Many pathogens use M cells to access the underlying Peyers patches and spread to systemic sites via the lymph as demonstrated by ligated loop murine intestinal models. However, the study of interactions between M cells and microbial pathogens has stalled due to the lack of cell culture systems. To overcome this obstacle, we use human ileal enteroid-derived monolayers containing five intestinal cell types including M cells to study the interactions between the enteric pathogen, Yersinia pseudotuberculosis (Yptb) and M cells. The Yptb type three secretion system (T3SS) effector Yops inhibit host defenses including phagocytosis and are critical for colonization of the intestine and Peyers patches. Therefore, it is not understood how Yptb traverses through M cells to breach the epithelium. By growing Yptb under two physiological conditions that mimic the early infectious stage (low T3SS-expression) or host-adapted stage (high T3SS-expression), we found that large numbers of Yptb specifically associated with M cells, recapitulating murine studies. Transcytosis through M cells was significantly higher by Yptb expressing low levels of T3SS, because YopE and YopH prevented Yptb uptake. YopE also caused M cells to extrude from the epithelium without inducing cell-death or disrupting monolayer integrity. Sequential infection with early infectious stage Yptb reduced host-adapted Yptb association with M cells. These data underscore the strength of enteroids as a model by discovering that Yops impede M cell function, indicating that early infectious stage Yptb more effectively penetrates M cells while the host may defend against M cell penetration of host-adapted Yptb.

microbiology↗

bioRxiv2019

Human Rotavirus Diarrhea Is Associated with Altered Trafficking and Expression of Apical Membrane Transport Proteins

BackgroundRotavirus (RV) is the 5th leading cause of death in children <5 years old but the leading cause of diarrhea related deaths in this age group. The mechanism of RV diarrhea involves decreased activity of Na+-dependent solute transporters with increased luminal secretion of Cl- in the absence of significant histologic damage. While our understanding of RV diarrhea has come from studies in animal models and cancer cell lines, the mechanism of the diarrhea and the transport proteins affected in human RV disease remains only partially understood. This understanding is likely to impact drug development therapy for RV diarrhea.\n\nMethodsFormalin-fixed paraffin-embedded small intestinal specimens from patients diagnosed with RV diarrhea (confirmed by anti-RV antibodies) were analyzed by immunofluorescence for changes in apical/basolateral ion/nutrient transporters/channels as well as tight junctional and cytoskeletal proteins. Proximal small intestinal enteroids generated from biopsies obtained from healthy human subjects were grown as monolayers, differentiated to resemble villus epithelial cells, and infected with human RV.\n\nResultsRV diarrhea was associated with reduced expression and intracellular localization of transport proteins normally found in the brush border membranes, including SGLT1, NHE3, NHE2, the Na+-dependent amino acid transporter SLC6A19, and CFTR. In contrast, basolateral proteins, including Na+/K+-ATPase, NKCC1, and {beta}-catenin, the brush border marker ezrin, as well as the tight junction protein, ZO-1, were expressed and localized normally. RV-induced mislocalization of NHE3, SGLT1, SLC6A19 and CFTR was also seen when human small intestinal enteroids were infected with RV.\n\nConclusionsThese data demonstrate a new pathophysiologic mechanism of acute diarrhea in which expression of multiple apical transport proteins are reduced. This acute diarrhea is likely to be caused by an effect on a common apical trafficking pathway, as exemplified by RV diarrhea, and its contribution to other enteric pathogen-induced diarrheal diseases should be determined.

cell biology↗

bioRxiv2018

Epithelial WNT2B and Desert Hedgehog are necessary for human colonoid regeneration after bacterial cytotoxin injury

Intestinal regeneration and crypt hyperplasia after radiation or pathogen injury relies on Wnt signaling to stimulate stem cell proliferation. Mesenchymal Wnts are essential for homeostasis and regeneration in mice, but the role of epithelial Wnts remains largely uncharacterized. Using the enterohemorrhagic E. coli secreted cytotoxin, EspP to induce injury to human colonoids, we evaluated a simplified, epithelial regeneration model that lacks mesenchymal Wnts. Here, we demonstrate that epithelial-produced WNT2B is upregulated following injury and essential for regeneration. Hedgehog signaling, specifically activation via the ligand Desert Hedgehog (DHH), but not Indian or Sonic Hedgehog, is another driver of regeneration and modulates WNT2B expression. These findings highlight the importance of epithelial WNT2B and DHH in regulating human colonic regeneration after injury.

physiology↗