Positive regulatory gamma delta T cells in contact sensitivity: augmented responses by in vivo treatment with anti-gamma delta monoclonal antibody, or anti-V gamma 5 or V delta 4

Detection of local inflammation induced by repeated exposure to contact allergens by use of IVIS SpectrumCT analyses

BACKGROUND

Contact allergy is characterized by local skin inflammation that, in some cases, can result in systemic immune activation.

OBJECTIVES

To investigate whether IVIS SpectrumCT analyses can be used to detect the immune response induced by contact allergens.

METHODS

Mice were repeatedly exposed to vehicle or allergens on the ears. The local and systemic responses were analysed at different times with the ProSense 750 FAST probe in IVIS SpectrumCT measurements. In addition, changes in ear thickness, cytokine profile in the skin and immunological phenotype in the draining lymph nodes and spleen were determined.

RESULTS

Local inflammation was detected by ProSense 750 FAST and correlated with changes in ear thickness, cytokine profile and immunological phenotype following exposure to the strong contact allergen 2,4-dinitrofluorobenzene. Analysis of the systemic response with ProSense 750 FAST did not show any difference between allergen-exposed and control mice, although fluorescence-activated cell sorting analysis of the spleen showed increased numbers of γδ T cells and CD11b⁺ CD11c⁺ MHCII⁺ cells in allergen-treated mice.

CONCLUSIONS

IVIS SpectrumCT analyses with ProSense 750 FAST as the probe can be used to detect local immune responses induced by contact allergens.

Epicutaneous immunization with ovalbumin and CpG induces TH1/TH17 cytokines, which regulate IgE and IgG2a production

BACKGROUND

Subcutaneous allergen-specific immunotherapy is a standard route for the immunotherapy of allergic diseases. It modulates the course of allergy and can generate long-term remission. However, subcutaneous allergen-specific immunotherapy can also induce anaphylaxis in some patients, and therefore additional routes of administration should be investigated to improve the safety and tolerability of immunotherapy.

OBJECTIVE

We sought to determine whether epicutaneous treatment with antigen in the presence of a Toll-like receptor 9 agonist can suppress TH2-mediated responses in an antigen-specific manner.

METHODS

Epicutaneous immunization was performed by applying a skin patch soaked with ovalbumin (OVA) plus CpG, and its suppressor activity was determined by using the mouse model of atopic dermatitis. Finally, adoptive cell transfers were implemented to characterize the regulatory cells that are induced by epicutaneous immunization.

RESULTS

Epicutaneous immunization with OVA and CpG reduces the production of OVA-specific IgE and increases the synthesis of OVA-specific IgG2a antibodies in an antigen-specific manner. Moreover, eosinophil peroxidase activity in the skin and production of IL-4, IL-5, IL-10, and IL-13 are suppressed. The observed reduction of IgE synthesis is transferable with T-cell receptor (TCR) αβ(+)CD4(+)CD25(-) cells, whereas IgG2a production is dependent on both TCRαβ(+) and TCRγδ(+) T cells. Further experiments show that the described phenomenon is myeloid differentiation primary response 88, IFN-γ, and IL-17A dependent. Finally, the results suggest that epicutaneous immunization with OVA and CpG decreases the synthesis of OVA-specific IgE and skin eosinophil peroxidase activity in mice with ongoing skin allergy.

CONCLUSION

Epicutaneous application of protein antigen in the presence of adjuvant could be an attractive needle-free and self-administered immunotherapy for allergic diseases.

Epicutaneous (EC) immunization with type II collagen (COLL II) induces CD4(+) CD8(+) T suppressor cells that protect from collagen-induced arthritis (CIA)

BACKGROUND

We have shown previously that epicutaneous (EC) immunization with protein antigen induces T suppressor cells that alleviate inflammatory response in contact hypersensitivity reactions, in an animal model of multiple sclerosis, and in TNBS-induced colitis.

METHODS

DBA/1 mice were EC immunized with type II collagen (COLL II) spread over a gauze patch on days 0 and 4. On day 7, patches were removed and mice were intradermally (id) immunized with COLL II in CFA to induce collagen-induced arthritis (CIA).

RESULTS

Our work shows that EC immunization with 100μg of COLL II prior to CIA induction reduces disease severity as determined by macroscopic evaluation. Reduced disease severity after EC immunization with COLL II correlates with milder histological changes found in joint sections. Experiments with the three non-cross-reacting antigens COLL II, ovalbumin (OVA) and myelin basic protein (MBP) showed that skin-induced suppression is antigen non-specific. Transfer experiments show that EC immunization with COLL II induces suppressor cells that belong to the population of CD4(+) CD8(+) double positive lymphocytes. Flow cytometry experiments showed increased percentage of CD4(+) CD8(+) RORγt(+) cells in axillary and inguinal lymph nodes isolated from mice patched with COLL II.

CONCLUSION

Maneuver of EC immunization with a protein antigen that induces suppressor cells to inhibit inflammatory responses may become an attractive, noninvasive, needle-free therapeutic method for different clinical situations.

Epicutaneous immunization with TNP-Ig and Zymosan induces TCRαβ+ CD4+ contrasuppressor cells that reverse skin-induced suppression via IL-17A

BACKGROUND

Our previous work showed that epicutaneous (EC) immunization with protein antigen e.g. TNP-conjugated mouse immunoglobulin (TNP-Ig) in the form of a patch prior to hapten sensitization inhibits Th1-mediated contact hypersensitivity (CHS) in mice. We also found that suppression of CHS was mediated by TCRαβ+ CD4+ CD8+ T suppressor cells producing TGF-β. The aim of this study was to investigate the role of innate immunity in the suppression of CHS.

METHODS

Mice were immunized by applying gauze patches containing protein antigen alone or in the presence of zymosan, and were then tested for the CHS response. Adoptive cell transfer experiments were used to study the mechanisms involved in the reversal of skin-induced suppression. The influence of EC immunization on cytokine production by lymph node cells was measured by ELISA.

RESULTS

We found that EC immunization with TNP-Ig and zymosan before trinitrophenyl chloride sensitization reverses skin-induced suppression, demonstrated in vivo and in vitro. The reversal of skin-induced suppression was transferable by antigen-specific TCRαβ+ CD4+ T contrasuppressor cells. Furthermore, we showed that the contrasuppression was IL-17A-dependent and TLR2- and MyD88-independent.

CONCLUSIONS

Our work strongly suggests that EC immunization with protein antigen and zymosan reverses skin-induced suppression and that this approach may be a potential tool to increase the immunogenicity of weakly immunogenic antigens.

Epicutaneous immunization with DNP-BSA induces CD4+ CD25+ Treg cells that inhibit Tc1-mediated CS

As we have shown previously that protein antigen applied epicutaneously (EC) in mice inhibits TNP-specific Th1-mediated contact sensitivity (CS), we postulated that the maneuver of EC immunization might also suppress Tc1-dependent CS response. Here we showed that EC immunization of normal mice with 2,4-dinitrophenylated bovine serum albumin (DNP-BSA) applied on the skin in the form of a patch induces a state of subsequent unresponsiveness due to regulatory T cells (Treg) that inhibited sensitization and elicitation of effector T-cell responses. Suppression is transferable in vivo by TCRαβ(+) CD4(+) CD25(+) lymphocytes harvested from lymph nodes (LNs) of skin-patched animals. Flow cytometry revealed that EC immunization with DNP-BSA increased TCRαβ(+) CD4(+) CD25(+) FoxP3(+) lymphocytes in subcutaneous LNs, suggesting that observed suppression was mediated by Treg cells. Further, in vitro experiments showed that EC immunization with DNP-BSA prior to 1-fluoro-2,4-dinitrobenzen sensitization suppressed LN cell proliferation and inhibited production of TNF-α, IL-12 and IFN-γ. Using a transwell system or anti-CTLA-4 mAb, we found that EC induced suppression required direct Treg-effector cell contact and is CTLA-4-dependent.

Functions of skin-resident γδ T cells

The murine epidermis contains resident T cells that express a canonical γδ TCR and arise from fetal thymic precursors. These cells are termed dendritic epidermal T cells (DETC) and use a TCR that is restricted to the skin in adult animals. DETC produce low levels of cytokines and growth factors that contribute to epidermal homeostasis. Upon activation, DETC can secrete large amounts of inflammatory molecules which participate in the communication between DETC, neighboring keratinocytes and langerhans cells. Chemokines produced by DETC may recruit inflammatory cells to the epidermis. In addition, cell-cell mediated immune responses also appear important for epidermal-T cell communication. Information is provided which supports a crucial role for DETC in inflammation, wound healing, and tumor surveillance.

Langerhans cells that have matured in vivo in the absence of T cells are fully capable of inducing a helper CD4 as well as a cytotoxic CD8 response

Langerhans cells (LCs) are immature dendritic cells (DCs) present in the skin epithelium. Upon Ag exposure, they migrate to the draining lymph nodes where they mature into potent stimulators of naive T cells. The aim of this study was to investigate the influence of T cells on LC migration and maturation. Therefore, the in vivo migration and maturation of LCs after sensitization with the hapten FITC was compared between C57BL/6 or BALB/c mice used as positive controls, and recombination activating gene (RAG) 1 knockout (-/-) mice or SCID mice used as T cell-deficient mice. Phenotypically, there was no difference between migrated LCs from RAG1-/- or SCID mice vs normal C57BL/6 or BALB/c mice: both populations of FITC+ cells had a dendritic morphology and a mature phenotype as they expressed high levels of MHC class II molecules and costimulatory molecules CD80, CD86, and CD54. Sorted migrated LCs of RAG1-/- or SCID mice were efficient stimulators of allogeneic T cells and Ag-specific CD4+ T cells. The same results were found if migrated LCs were fixed instead of irradiated, excluding the possibility that LCs derived from RAG1-/- or SCID mice would mature in the presence of T cells during the stimulation tests. Importantly, fixed migrated LCs of RAG1-/- mice were also efficient stimulators of cytotoxic CD8+ T cells. These data suggest that T cells are not required for full maturation of LCs.

Role of interleukin-4 in down-regulation of contact sensitivity by gammadelta T cells from tolerized T-cell receptor alpha-/- mice

Contact sensitivity (CS) is a classical example of an in vivo T-cell-mediated immune response that is under regulation. Such down-regulation can be mediated by alphabeta T cells in mice that are tolerized by prior exposure to high doses of antigen. In contrast, we demonstrated previously that such high-dose antigen tolerance in T-cell receptor (TCR) alpha-/- H-2d mice induced antigen-specific, apparently major histocompatibility complex-unrestricted, CD4- CD8- gammadelta T cells, that also could down-regulate CS responses antigen-specifically in vivo, and also inhibited in vitro production of IFN-gamma. In the present experiments we employed H-2b-deficient TCRalpha-/- and TCRbeta-/- mice, owing to different molecular constructs than were used previously, and confirmed that tolerized gammadelta T cells in these different H-2b alphabeta TCR-/- mice down-regulated CS. Thus, gammadelta T-cell suppressor function was not limited to mice bearing a special transgenic TCRalpha-/- DNA construct. Furthermore, employing monoclonal antibody and complement depletion in vitro and adoptive transfer in vivo, characterized the phenotype of these gammadelta down-regulatory T cells as: CD3+, CD28+, CD40-ligand+, Fas+, FcgammaR+ and NK1.1-. Also, in vitro antigen desensitization of these trinitrophenyl (TNP)-specific TCRgammadelta+ down-regulatory cells was achieved with soluble TNP-bovine serum albumin (BSA), but not with oxazolone-BSA, showing that these suppressive gammadelta T cells have antigen-specific receptors. Moreover, employing monoclonal antibody blocking of gammadelta suppressors in vitro, and of recipients in vivo, we showed that interleukin-4 (IL-4) was involved in this down-regulation of CS by gammadelta T cells, while IL-10 and transforming growth factor-beta2 were not. In summary, generation of antigen-specific, double-negative, gammadelta suppressor cells, by tolerance of high antigen doses in TCRalpha-/- mice, appears to be a general phenomenon, and IL-4 production is involved in their down-regulation of the T helper type 1 cells that mediate CS.

Cross-talk between gammadelta T lymphocytes and immune cells in humoral response

The role of gamma delta T cells in immunoregulation is largely unknown. In the current study we noted that gamma delta T cells play a positive role in the humoral response. These positively acting gamma delta T cells are required for the successful adoptive cell transfer of the humoral response, as well as for in vitro generation of plaque-forming cells (PFC). The presented results show that gammadelta T cells cause an increase in interleukin-10 (IL-10) production, which partly elucidates the mechanism of action of these cells. However, experiments with cell culture inserts strongly suggest that direct cell-cell contact between immune and gamma delta H-2-compatible regulatory T cells is critical to the exertion of the positive immunoregulatory function of gamma delta cells. The mechanism of cross-talk between these two cell populations is still not clear but we regard as most likely that the positively acting gamma delta T cells may interact with a complex of heat-shock protein-non-polymorphic MHC (IB) on the surface of T helper type 2 and/or B cells. This could provide, by direct cell-cell contact, the cognate recognition between gamma delta T-cell receptors and heat-shock protein-MHC that leads to positive internal signalling in the immune cells.