RESUMO

Dendritic cells are central to the development of immunity, as they are specialized in initiating antigen-specific immune responses. In this review, we briefly present the existing knowledge on dendritic cell biology and how their division in different dendritic cell subsets may impact the development of immune responses. In addition, we explore the use of chimeric monoclonal antibodies that bind to dendritic cell surface receptors, with an emphasis on the C-type lectin family of endocytic receptors, to deliver antigens directly to these cells. Promising preclinical studies have shown that it is possible to modulate the development of immune responses to different pathogens when monoclonal antibodies fused to pathogen-derived antigens are used to deliver the antigen to different subsets of dendritic cells. This approach can be used to improve the efficacy of vaccines against different pathogens.

Assuntos

Vacinas , Receptores de Superfície Celular/metabolismo , Lectinas Tipo C/metabolismo , Anticorpos Monoclonais , Células Dendríticas

RESUMO

Dendritic cell (DC) targeting by DEC205+ cells effectively promotes the internalization of antigens that may trigger a specific immune response. In this study, we evaluated the ability of a recombinant antibody, anti-DEC205 (rAb ZH9F7), to trigger cellular endocytosis in subpopulations of DCs and targeted cells after intradermal injection and subsequent migration toward lymph nodes. Furthermore, the cellular immune response was evaluated in pigs after intradermal application of the antigenized rAb ZH9F7 combined with porcine circovirus type 2 cap antigen (rAb ZH9F7-Cap). We demonstrated that rAb ZH9F7 recognized conventional type 1 and 2 DCs from the blood and skin and monocytes. It promoted receptor-mediated endocytosis and migration of cDCs and moDCs toward regional lymph nodes. Intradermal application of rAb ZH9F7-Cap induced a higher frequency of IFN-γ-secreting CD4+CD8+ T lymphocytes and antibodies against Cap protein than that in the control group. In conclusion, the rAb ZH9F7-Cap system promoted the target of skin cDC1 and cDC2, provoking migration to the regional lymph nodes and inducing a Th1 response, as evidenced by the proliferation of double-positive CD4+CD8+ T cells, which correlates with an enhanced ability to target the cDC1 subset both in vitro and in vivo.

RESUMO

Conventional dendritic cells (cDCs) are antigen-presenting cells specialized in naïve T cell priming. Mice splenic cDCs are classified as cDC1s and cDC2s, and their main functions have been elucidated in the last decade. While cDC1s are specialized in priming type 1 helper T cells (TH1) and in cross presentation, cDC2s prime T follicular helper (TFH) cells that stimulate germinal center (GC) formation, plasma cell differentiation and antibody production. However, less is known about the molecular mechanisms used by cDCs to prime those responses. Here, using WT and STAT6-deficient mice (STAT6 KO), we targeted a model antigen to cDC1s and cDC2s via DEC205 and DCIR2 receptors, respectively, in an attempt to study whether the STAT6 signaling pathway would modulate cDCs' ability to prime helper T cells. We show that the differentiation and maturation of cDCs, after stimulation with an adjuvant, were comparable between WT and STAT6 KO mice. Besides, our results indicate that, in STAT6 KO mice, antigen targeting to cDC2s induced reduced TFH and GC responses, but did not alter plasma cells numbers and antibody titers. Thus, we conclude that the STAT6 signaling pathway modulates the immune response after antigen targeting to cDC2s via the DCIR2 receptor: while STAT6 stimulates the development of TFH cells and GC formation, plasma cell differentiation occurs in a STAT6 independent manner.

RESUMO

Conventional dendritic cells (cDCs) are specialized in antigen presentation. In the mouse spleen, cDCs are classified in cDC1s and cDC2s, and express DEC205 and DCIR2 endocytic receptors, respectively. Monoclonal antibodies (mAbs) αDEC205 (αDEC) and αDCIR2 have been fused to different antigens to deliver them to cDC1s or cDC2s. We immunized mice with αDEC and αDCIR2 fused to an antigen using Poly(I:C) as adjuvant. The initial immune response was analyzed from days 3 to 6 after the immunization. We also studied the influence of a booster dose. Our results showed that antigen targeting to cDC1s promoted a pro-inflammatory TH 1 cell response. Antigen targeting to cDC2s induced TFH cells, GCs, and plasma cell differentiation. After boost, antigen targeting to cDC1s improved the TH 1 cell response and induced TH 1-like TFH cells that led to an increase in specific antibody titers and IgG class switch. Additionally, a population of regulatory T cells was also observed. Antigen targeting to cDC2s did not improve the specific antibody response after boost. Our results add new information on the immune response induced after the administration of a booster dose with αDEC and αDCIR2 fusion mAbs. These results may be useful for vaccine design using recombinant mAbs.

Assuntos

Células Dendríticas/imunologia , Receptores de Superfície Celular/imunologia , Células T Auxiliares Foliculares/imunologia , Linfócitos T Reguladores/imunologia , Células Th1/imunologia , Animais , Anticorpos Monoclonais/imunologia , Formação de Anticorpos/imunologia , Apresentação de Antígeno/imunologia , Feminino , Ativação Linfocitária/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Poli I-C/imunologia

RESUMO

Activation of the immune system using antigen targeting to the dendritic cell receptor DEC205 presents great potential in the field of vaccination. The objective of this work was to evaluate the immunogenicity and protectiveness of a recombinant mouse x pig chimeric antibody fused with peptides of structural and nonstructural proteins of porcine respiratory and reproductive syndrome virus (PRRSV) directed to DEC205+ cells. Priming and booster immunizations were performed three weeks apart and administered intradermally in the neck area. All pigs were challenged with PRRSV two weeks after the booster immunization. Immunogenicity was evaluated by assessing the presence of antibodies anti-PRRSV, the response of IFN-γ-producing CD4+ cells, and the proliferation of cells. Protection was determined by assessing the viral load in the blood, lungs, and tonsils using qRT-PCR. The results showed that the vaccine exhibited immunogenicity but conferred limited protection. The vaccine group had a lower viral load in the tonsils and a significantly higher production of antibodies anti-PRRSV than the control group (p < 0.05); the vaccine group also produced more CD4+IFN-γ+ cells in response to peptides from the M and Nsp2 proteins. In conclusion, this antigenized recombinant mouse x pig chimeric antibody had immunogenic properties that could be enhanced to improve the level of protection and vaccine efficiency.

RESUMO

Dendritic cells (DCs) are antigen-presenting cells essential for the induction of adaptive immune responses. Their unprecedented ability to present antigens to T cells has made them excellent targets for vaccine development. In the last years, a new technology based on antigen delivery directly to different DC subsets through the use of hybrid monoclonal antibodies (mAbs) to DC surface receptors fused to antigens of interest opened new perspectives for the induction of robust immune responses. Normally, the hybrid mAbs are administered with adjuvants that induce DC maturation. In this work, we targeted an antigen to the CD8α+ or the CD8α- DC subsets in the presence of CpG oligodeoxinucleotides (ODN) or bacterial flagellin, using hybrid αDEC205 or αDCIR2 mAbs, respectively. We also accessed the role of toll-like receptors (TLRs) 5 and 9 signaling in the induction of specific humoral and cellular immune responses. Wild-type and TLR5 or TLR9 knockout mice were immunized with two doses of the hybrid αDEC205 or αDCIR2 mAbs, as well as with an isotype control, together with CpG ODN 1826 or flagellin. A chimeric antigen containing the Plasmodium vivax 19 kDa portion of the merozoite surface protein (MSP119) linked to the Pan-allelic DR epitope was fused to each mAb. Specific CD4+ T cell proliferation, cytokine, and antibody production were analyzed. We found that CpG ODN 1826 or flagellin were able to induce CD4+ T cell proliferation, CD4+ T cells producing pro-inflammatory cytokines, and specific antibodies when the antigen was targeted to the CD8α+ DC subset. On the other hand, antigen targeting to CD8α- DC subset promoted specific antibody responses and proliferation, but no detectable pro-inflammatory CD4+ T cell responses. Also, specific antibody responses after antigen targeting to CD8α+ or CD8α- DCs were reduced in the absence of TLR9 or TLR5 signaling, while CD4+ T cell proliferation was mainly affected after antigen targeting to CD8α+ DCs and in the absence of TLR9 signaling. These results extend our understanding of the modulation of specific immune responses induced by antigen targeting to DCs in the presence of different adjuvants. Such knowledge may be useful for the optimization of DC-based vaccines.