Gene expression profiling identifies STAT3 as a novel pathway for immunomodulation by cholera toxin adjuvant

Abstract

Earlier studies have reported on both proinflammatory and anti-inflammatory activities of cholera toxin (CT). As CT is a powerful adjuvant, we were interested in identifying genes with a possible involvement in these functions. A global gene expression analysis in mouse B cells showed that CT regulated <100 annotated genes, which encoded transcription factors, G proteins, cell-cycle regulators, and immunoregulating molecules. Interestingly, CT regulated the expression of the signal transducer and activator of transcription (STAT)3 gene and influenced the level and activation of both isoforms STAT3 alpha and STAT3 beta, in vitro in a B-cell line and in Peyer's patch (PP) B cells and in vivo in freshly isolated splenic B cells from CT-treated mice. This effect was cAMP dependent and was not seen with CTB. B cells pre-exposed to CT were significantly more susceptible to the activation of STAT3 by interleukin (IL)-6 and IL-10. This exerted a stronger inhibitory effect of IL-10 on lipopolysaccharide (LPS)-stimulated B-cell proliferation and cytokine production (IL-6). Moreover, IgG1 and IgA production induced by LPS and IL-10 were enhanced by the addition of CT to cultures of PP or splenic B cells. This is the first study to provide a molecular mechanism that can reconcile previous findings of proinflammatory and anti-inflammatory effects by CT adjuvant.

Innate transcriptional effects by adjuvants on the magnitude, quality, and durability of HIV envelope responses in NHPs

“…[37][38][39][40][41] Recent studies have used systems serology analyses to qualitatively assess antibody responses based on Fc-mediated effector functions, [42][43][44][45][46][47] which have been found to play a role in protection against simian immunodeficiency virus (SIV) 48 and HIV. 4 To assess the mechanisms by which adjuvants and vaccines mediate such effector functions, transcriptional profiling has been used in mouse models, [49][50][51][52] as well as in humans to define biomarkers to predict protection. [53][54][55] However, mouse studies are limited because the tissue distribution of TLR expression is different than humans, 56 and it is difficult to profile multiple vaccine adjuvants simultaneously in humans.…”

Selective Induction of Homeostatic Th17 Cells in the Murine Intestine by Cholera Toxin Interacting with the Microbiota

“…With SFB as a known stimulator of endogenous Th17 cells in the intestine, we found that in addition, other commensal bacteria such as those belonging to the altered Schaedler flora, can also participate in the regulation of intestinal Th17 and antibody responses to CT mucosal immunization. When the CTB subunit binds to the GM1 ganglioside present on cell membranes, CT induces strong activation of STAT3 signaling and massive production of IL-6 11,51,52 , which is known to promote the differentiation of Th17 cells in vitro . However, in agreement with previously published in vitro studies 53,54 , IL-6 −/− mice did not show impaired intestinal Th17 cell induction upon CT immunization compared to littermate WT mice (Supplementary Fig.…”

Mechanisms of Cholera Toxin in the Modulation of TH17 Responses

“…94 CT also induces IL-1 and IL-6 production by B cells, macrophages and DCs, and upregulates the expression of costimulatory molecules (CD80, CD86, HLA-DR) on DCs. 95–98 However, in some studies, CT reduced IL-12 production and induced IL-10 expression and the overall responses had an anti-inflammatory effect. 99–101 Although in vivo CT administration in some studies induced a T H 1 response, 102,103 in most studies CT promoted a strong T H 2-bias response to CT itself and to bystander antigens and suppressed a T H 1-bias response.…”