Intraperitoneal Immunization with Cry1Ac Protoxin from Bacillus thuringiensis Provokes Upregulation of Fc‐Gamma‐II/and Fc‐Gamma‐III Receptors Associated with IgG in the Intestinal Epithelium of Mice

Abstract

In humans, intestinal epithelial FcRn is expressed throughout life and mediates the bidirectional transport of IgG, but in mice, it is markedly expressed in neonatal intestine. In adults, its expression is only faintly upregulated after intestinal IgG induction such as that elicited by i.p. immunization with Cry1Ac protoxin (pCry1Ac) Bacillus thuringiensis. This led us to suggest that additional Fcγ receptors (Fcγ‐R) may be participating in epithelial IgG uptake. So, first we determined whether CD16/32 [an epitope shared by Fcγ‐RII (CD32) and Fcγ‐RIII (CD16)] was expressed in the intestinal epithelia of mice. Using confocal microscopy and flow cytometry, we detected co‐localization of IgG and CD16/32 in epithelial cells, whose frequency was increased by immunization with pCry1Ac. Western blot and cross‐immunoprecipitation results with anti‐CD16/32 and IgG antibodies in epithelial cell extracts suggested that epithelial cells bear both Fcγ‐RII and Fcγ‐RIII and contained IgG associated with Fcγ‐RII/RIII. Using anti‐CD32 and anti‐CD16 antibodies, we confirmed by Western blot, confocal microscopy and flow cytometry that both Fcγ‐RII and Fcγ‐RIII were expressed and suggested that upregulation occurred upon immunization in intestinal epithelia. Finally, we examined the in vitro effect of anti‐CD16/32, anti‐CD16 and anti‐CD32 antibodies on IgG uptake and transport by intestinal epithelial cells and found that it was partially reduced. Although further studies are still required, our results suggest that Fcγ‐RII and Fcγ‐RIII might participate in the uptake and/or transport of IgG through the intestinal epithelia of adult mice.

Cells of the human intestinal tract mapped across space and time

“…This is surprising since FcG receptors have rarely been observed in non-haematopoietic cells 57 . To our knowledge, FcgrII expression has only been observed in mouse intestinal epithelial cells after immunization with bacterial neurotoxin 23 and by human nasal epithelial cells in response to bacteria-derived ligands 58 . We also note expression of the FCGR2A by our previously described thymic mTEC(II) epithelial population, which expresses low levels of tuft cell transcription factor POU2F3 (developmentcellatlas.ncl.ac.uk).…”

“…3K). Among these, only FCGR2A, which is activated in response to IgG and shown to be expressed by epithelial cells in immunized mice 23 , was specifically expressed by a fraction (2.75%) of tuft cells (Figure 2E). Using the mouse as a model, we confirmed expression of Fcgr3 (ortholog of FCGR2A) at protein level by approximately 5% of small intestinal tuft cells (Figure 2F & Supplementary Fig.…”

Cells of the human intestinal tract mapped across space and time

“…6i ). FCGR2A, which is activated in response to IgG and expressed by selected epithelial cells in immunized mice 21 , was specifically expressed by approximately 2.75% of tuft cells (Fig. 2f ).…”

Humoral and cellular immune response in Wistar Han RCC rats fed two genetically modified maize MON810 varieties for 90 days (EU 7th Framework Programme project GRACE)

“…In particular, an increased antibody response against an unrelated protein (i.e. ovalbumin) was observed (Vázquez-Padrón et al 1999 ; González-González et al 2015 ; Moreno-Fierros et al 2015 ). In contrast, the adjuvant effect of Cry1Ab on ovalbumin was not observed in BALB/c mice after airway exposure to extracts of MON810 pollen/leaf or trypsinized Cry1Ab (Andreassen et al 2015b ).…”