To better understand the innate immune response to
Vibrio cholerae infection, we tracked gene expression in the duodenal mucosa of 11 Bangladeshi adults with
cholera, using biopsy specimens obtained immediately after
rehydration and 30 and 180 days later. We identified differentially expressed genes and performed an analysis to predict differentially regulated pathways and upstream regulators. During acute
cholera, there was a broad increase in the expression of genes associated with innate immunity, including activation of the NF-κB,
mitogen-activated protein kinase (MAPK), and
Toll-like receptor (TLR)-mediated signaling pathways, which, unexpectedly, persisted even 30 days after
infection. Focusing on early differences in gene expression, we identified 37 genes that were differentially expressed on days 2 and 30 across the 11 participants. These genes included the endosomal
Toll-like receptor gene TLR8, which was expressed in lamina propria cells. Underscoring a potential role for endosomal TLR-mediated signaling in vivo, our pathway analysis found that
interferon regulatory factor 7 and beta 1 and alpha 2
interferons were among the top upstream regulators activated during
cholera. Among the innate immune effectors, we found that the gene for
DUOX2, an
NADPH oxidase involved in the maintenance of intestinal homeostasis, was upregulated in intestinal epithelial cells during
cholera. Notably, the observed increases in
DUOX2 and TLR8 expression were also modeled in vitro when Caco-2 or THP-1 cells, respectively, were stimulated with live V. cholerae but not with heat-killed organisms or
cholera toxin alone. These previously unidentified features of the innate immune response to V. cholerae extend our understanding of the mucosal immune signaling pathways and effectors activated in vivo following
cholera.