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Dendritic cell-bound IgE functions to restrain allergic inflammation at mucosal sites.

Platzer B, Baker K, Vera MP, Singer K, Panduro M, Lexmond WS, Turner D, Vargas SO, Kinet JP, Maurer D, Baron RM, Blumberg RS, Fiebiger E - Mucosal Immunol (2014)

Bottom Line: Furthermore, conferring expression of FcɛRI to DCs decreases the severity of food allergy and asthma in disease-relevant models suggesting anti-inflammatory IgE/FcɛRI signals.Consistent with the improved clinical parameters in vivo, antigen-specific IgE/FcɛRI cross-linking on papain or lipopolysaccharide-stimulated DCs inhibits the production of pro-inflammatory cytokines and chemokines.Our study demonstrates a novel immune regulatory function of IgE and proposes that DC-intrinsic IgE signals serve as a feedback mechanism to restrain allergic tissue inflammation.

View Article: PubMed Central - PubMed

Affiliation: Division of Gastroenterology and Nutrition, Boston Children's Hospital and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA.

ABSTRACT
Antigen-mediated cross-linking of Immunoglobulin E (IgE) bound to mast cells/basophils via FcɛRI, the high affinity IgE Fc-receptor, is a well-known trigger of allergy. In humans, but not mice, dendritic cells (DCs) also express FcɛRI that is constitutively occupied with IgE. In contrast to mast cells/basophils, the consequences of IgE/FcɛRI signals for DC function remain poorly understood. We show that humanized mice that express FcɛRI on DCs carry IgE like non-allergic humans and do not develop spontaneous allergies. Antigen-specific IgE/FcɛRI cross-linking fails to induce maturation or production of inflammatory mediators in human DCs and FcɛRI-humanized DCs. Furthermore, conferring expression of FcɛRI to DCs decreases the severity of food allergy and asthma in disease-relevant models suggesting anti-inflammatory IgE/FcɛRI signals. Consistent with the improved clinical parameters in vivo, antigen-specific IgE/FcɛRI cross-linking on papain or lipopolysaccharide-stimulated DCs inhibits the production of pro-inflammatory cytokines and chemokines. Migration assays confirm that the IgE-dependent decrease in cytokine production results in diminished recruitment of mast cell progenitors; providing a mechanistic explanation for the reduced mast cell-dependent allergic phenotype observed in FcɛRI-humanized mice. Our study demonstrates a novel immune regulatory function of IgE and proposes that DC-intrinsic IgE signals serve as a feedback mechanism to restrain allergic tissue inflammation.

No MeSH data available.


Related in: MedlinePlus

IgE/FcεRI-crosslinking does not induce phenotypic maturation or production of inflammatory cytokines in DCs. (a) Antigen-mediated IgE/FcεRI activation induces phosphorylation of Syk and Erk1/2 in DCs. Splenic DCs were loaded with NP-specific IgE prior to incubation with NP-OVA (see schematic). IgER-TG DCs were also stimulated with CpG DNA, or antigen-crosslinking was omitted (NT = not treated). As a control, WT DCs were treated identically. Immunoblots for phospho-Syk, total Syk, phospho-Erk1/2 or total Erk1/2 are shown. (b) IgE/FcεRI-crosslinking fails to upregulate expression of maturation marker molecules in DCs from IgER-TG mice and (c) human monocyte-derived DCs. (d) Absence of cytokine secretion by splenic DCs upon antigen-specific IgE/FcεRI-crosslinking. Mean of triplicates +/− SEM, representative experiment (n=2); below detection level (bd) (e) TNF-α secretion from bone-marrow derived mast cells upon antigen-specific IgE/FcεRI-crosslinking. (f) Absence of transcriptional responses in murine DCs after antigen-specific IgE/FcεRI-crosslinking. mRNA expression was determined after 8 h. OVA uptake in the presence of CpG-DNA or papain was compared to IgE/FcεRI-mediated OVA uptake. Fold change compared to DCs that received OVA was calculated, and the mean of triplicates +/− SEM is shown, representative experiment (n=2).
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Figure 2: IgE/FcεRI-crosslinking does not induce phenotypic maturation or production of inflammatory cytokines in DCs. (a) Antigen-mediated IgE/FcεRI activation induces phosphorylation of Syk and Erk1/2 in DCs. Splenic DCs were loaded with NP-specific IgE prior to incubation with NP-OVA (see schematic). IgER-TG DCs were also stimulated with CpG DNA, or antigen-crosslinking was omitted (NT = not treated). As a control, WT DCs were treated identically. Immunoblots for phospho-Syk, total Syk, phospho-Erk1/2 or total Erk1/2 are shown. (b) IgE/FcεRI-crosslinking fails to upregulate expression of maturation marker molecules in DCs from IgER-TG mice and (c) human monocyte-derived DCs. (d) Absence of cytokine secretion by splenic DCs upon antigen-specific IgE/FcεRI-crosslinking. Mean of triplicates +/− SEM, representative experiment (n=2); below detection level (bd) (e) TNF-α secretion from bone-marrow derived mast cells upon antigen-specific IgE/FcεRI-crosslinking. (f) Absence of transcriptional responses in murine DCs after antigen-specific IgE/FcεRI-crosslinking. mRNA expression was determined after 8 h. OVA uptake in the presence of CpG-DNA or papain was compared to IgE/FcεRI-mediated OVA uptake. Fold change compared to DCs that received OVA was calculated, and the mean of triplicates +/− SEM is shown, representative experiment (n=2).

Mentions: Aiming at characterizing the consequences of IgE/FcεRI-crosslinking for DC activation, we next modeled antigen-specific signals via IgE/FcεRI. Splenic DCs from IgER-TG mice were loaded with monomeric hapten-specific IgE (NP-IgE), and haptenized antigen (NP-OVA) was used to engage surface FcεRI (Figure 2a). It has been previously described that DCs from IgER-TG animals express the trimeric receptor as a chimera of the human α-chain and the rodent γ-chains.31 We found that crosslinking of IgE/FcεRI induced rapid phosphorylation of spleen tyrosine kinase (Syk) and extracellular signal-regulated kinases (Erk1 and Erk2), which was not seen in identically treated WT DCs or after stimulation of DC with CpG DNA (Figure 2a). These results demonstrate that the signaling cascade down-stream of FcεRI on DCs involves signaling molecules that also have been described downstream of the tetrameric FcεRI in human and mouse mast cells.35


Dendritic cell-bound IgE functions to restrain allergic inflammation at mucosal sites.

Platzer B, Baker K, Vera MP, Singer K, Panduro M, Lexmond WS, Turner D, Vargas SO, Kinet JP, Maurer D, Baron RM, Blumberg RS, Fiebiger E - Mucosal Immunol (2014)

IgE/FcεRI-crosslinking does not induce phenotypic maturation or production of inflammatory cytokines in DCs. (a) Antigen-mediated IgE/FcεRI activation induces phosphorylation of Syk and Erk1/2 in DCs. Splenic DCs were loaded with NP-specific IgE prior to incubation with NP-OVA (see schematic). IgER-TG DCs were also stimulated with CpG DNA, or antigen-crosslinking was omitted (NT = not treated). As a control, WT DCs were treated identically. Immunoblots for phospho-Syk, total Syk, phospho-Erk1/2 or total Erk1/2 are shown. (b) IgE/FcεRI-crosslinking fails to upregulate expression of maturation marker molecules in DCs from IgER-TG mice and (c) human monocyte-derived DCs. (d) Absence of cytokine secretion by splenic DCs upon antigen-specific IgE/FcεRI-crosslinking. Mean of triplicates +/− SEM, representative experiment (n=2); below detection level (bd) (e) TNF-α secretion from bone-marrow derived mast cells upon antigen-specific IgE/FcεRI-crosslinking. (f) Absence of transcriptional responses in murine DCs after antigen-specific IgE/FcεRI-crosslinking. mRNA expression was determined after 8 h. OVA uptake in the presence of CpG-DNA or papain was compared to IgE/FcεRI-mediated OVA uptake. Fold change compared to DCs that received OVA was calculated, and the mean of triplicates +/− SEM is shown, representative experiment (n=2).
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Figure 2: IgE/FcεRI-crosslinking does not induce phenotypic maturation or production of inflammatory cytokines in DCs. (a) Antigen-mediated IgE/FcεRI activation induces phosphorylation of Syk and Erk1/2 in DCs. Splenic DCs were loaded with NP-specific IgE prior to incubation with NP-OVA (see schematic). IgER-TG DCs were also stimulated with CpG DNA, or antigen-crosslinking was omitted (NT = not treated). As a control, WT DCs were treated identically. Immunoblots for phospho-Syk, total Syk, phospho-Erk1/2 or total Erk1/2 are shown. (b) IgE/FcεRI-crosslinking fails to upregulate expression of maturation marker molecules in DCs from IgER-TG mice and (c) human monocyte-derived DCs. (d) Absence of cytokine secretion by splenic DCs upon antigen-specific IgE/FcεRI-crosslinking. Mean of triplicates +/− SEM, representative experiment (n=2); below detection level (bd) (e) TNF-α secretion from bone-marrow derived mast cells upon antigen-specific IgE/FcεRI-crosslinking. (f) Absence of transcriptional responses in murine DCs after antigen-specific IgE/FcεRI-crosslinking. mRNA expression was determined after 8 h. OVA uptake in the presence of CpG-DNA or papain was compared to IgE/FcεRI-mediated OVA uptake. Fold change compared to DCs that received OVA was calculated, and the mean of triplicates +/− SEM is shown, representative experiment (n=2).
Mentions: Aiming at characterizing the consequences of IgE/FcεRI-crosslinking for DC activation, we next modeled antigen-specific signals via IgE/FcεRI. Splenic DCs from IgER-TG mice were loaded with monomeric hapten-specific IgE (NP-IgE), and haptenized antigen (NP-OVA) was used to engage surface FcεRI (Figure 2a). It has been previously described that DCs from IgER-TG animals express the trimeric receptor as a chimera of the human α-chain and the rodent γ-chains.31 We found that crosslinking of IgE/FcεRI induced rapid phosphorylation of spleen tyrosine kinase (Syk) and extracellular signal-regulated kinases (Erk1 and Erk2), which was not seen in identically treated WT DCs or after stimulation of DC with CpG DNA (Figure 2a). These results demonstrate that the signaling cascade down-stream of FcεRI on DCs involves signaling molecules that also have been described downstream of the tetrameric FcεRI in human and mouse mast cells.35

Bottom Line: Furthermore, conferring expression of FcɛRI to DCs decreases the severity of food allergy and asthma in disease-relevant models suggesting anti-inflammatory IgE/FcɛRI signals.Consistent with the improved clinical parameters in vivo, antigen-specific IgE/FcɛRI cross-linking on papain or lipopolysaccharide-stimulated DCs inhibits the production of pro-inflammatory cytokines and chemokines.Our study demonstrates a novel immune regulatory function of IgE and proposes that DC-intrinsic IgE signals serve as a feedback mechanism to restrain allergic tissue inflammation.

View Article: PubMed Central - PubMed

Affiliation: Division of Gastroenterology and Nutrition, Boston Children's Hospital and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA.

ABSTRACT
Antigen-mediated cross-linking of Immunoglobulin E (IgE) bound to mast cells/basophils via FcɛRI, the high affinity IgE Fc-receptor, is a well-known trigger of allergy. In humans, but not mice, dendritic cells (DCs) also express FcɛRI that is constitutively occupied with IgE. In contrast to mast cells/basophils, the consequences of IgE/FcɛRI signals for DC function remain poorly understood. We show that humanized mice that express FcɛRI on DCs carry IgE like non-allergic humans and do not develop spontaneous allergies. Antigen-specific IgE/FcɛRI cross-linking fails to induce maturation or production of inflammatory mediators in human DCs and FcɛRI-humanized DCs. Furthermore, conferring expression of FcɛRI to DCs decreases the severity of food allergy and asthma in disease-relevant models suggesting anti-inflammatory IgE/FcɛRI signals. Consistent with the improved clinical parameters in vivo, antigen-specific IgE/FcɛRI cross-linking on papain or lipopolysaccharide-stimulated DCs inhibits the production of pro-inflammatory cytokines and chemokines. Migration assays confirm that the IgE-dependent decrease in cytokine production results in diminished recruitment of mast cell progenitors; providing a mechanistic explanation for the reduced mast cell-dependent allergic phenotype observed in FcɛRI-humanized mice. Our study demonstrates a novel immune regulatory function of IgE and proposes that DC-intrinsic IgE signals serve as a feedback mechanism to restrain allergic tissue inflammation.

No MeSH data available.


Related in: MedlinePlus