CD301b⁺ dermal dendritic cells drive T helper 2 cell-mediated immunity

Abstract

Unlike other types of T helper (Th) responses, whether the development of Th2 cells requires instruction from particular subset of dendritic cells (DCs) remains unclear. By using an in vivo depletion approach, we have shown that DCs expressing CD301b were required for the generation of Th2 cells after subcutaneous immunization with ovalbumin (OVA) along with papain or alum. CD301b⁺ DCs are distinct from epidermal or CD207⁺ dermal DCs (DDCs) and were responsible for transporting antigen injected subcutaneously with Th2-type adjuvants. Transient depletion of CD301b⁺ DCs resulted in less effective accumulation and decreased expression of CD69 by polyclonal CD4⁺ T cells in the lymph node. Moreover, despite intact cell division and interferon-γ production, CD301b⁺ DC depletion led to blunted interleukin-4 production by OVA-specific OT-II transgenic CD4⁺ T cells and significantly impaired Th2 cell development upon infection with Nippostrongylus brasiliensis. These results reveal CD301b⁺ DDCs as the key mediators of Th2 immunity.

Figure 1. Expression of CD301b by the major DC population in the dermis and submucosae

(A) Expression of CD301b, CD326 (LC marker) and CD103 (CD207⁺DDC marker) in naïve cutaneous LN. Cells within the CD11c⁺MHCII⁺B220⁻ gate are shown. (B) Frozen sections of skin, vagina, esophagus and tongue from naïve C57BL/6 mice were stained with Ab against CD301b (green), CD207 (red, left) and CD11c (red, right). Scale bar represents 100 μm. E: Epidermis, L: Lumen. These data are representative of three or more similar experiments. See also Figure S1.

Figure 2. Uptake of soluble protein antigen by CD301b⁺DDCs in the skin-draining LNs

Mice were injected with Alexa Fluor 488 (A488)-labeled OVA protein with the indicated adjuvant in the footpad. Twenty-four hors later, the draining popliteal LNs were harvested and stained for DC markers. The total live LN cells are shown. These data are representative of three independent experiments. See also Figure S2.

Figure 3. Depletion of CD301b⁺ DDCs in Mgl2DTR mice

(A) Mice of indicated genotype were intraperitoneally injected with PBS or DT. Two days later, skin-draining LNs were harvested and stained for CD301b or DTR-GFP. Scale bar = 100μm. (B) Skin-draining LN DCs one day after DT injection were stained for CD301b and CD207⁺DC markers. (C) Kinetics of CD301b⁺DDC depletion in the skin-draining LNs in Mgl2DTR mice. The percentage of CD301b⁺DCs in the total LN cells is shown as mean ± SEM. n = 4 – 6 per time point. (D) Depletion of CD301b⁺DDCs abolishes the influx of hapten-bearing DCs in the dLN. DT-treated WT C57BL/6 (WT B6) or Mgl2DTR mice were painted with TRITC dissolved in 1:1 mixture of acetone:di-n-butylphthalate on the shaved abdomen. Twenty-four hours later, the draining (right) and non-draining contralateral (left) inguinal LNs were harvested. The total live LN cells are shown. These data are representative of two similar experiments. See also Figures S3 and S4.

Figure 4. Requirement of CD301b⁺ DDCs for accumulation and activation of polyclonal CD4⁺T cells in the dLN upon immunization with papain

Wild-type or Mgl2DTR mice were intraperitoneally injected with DT. One day later, the mice were immunized with papain in the right hind footpad. (A–G) The draining right or non-draining left popliteal LNs were harvested three days after immunization and the total LN cellularity (a) and the number (B–D) and the percentage in the total dLN cells (E–G) of CD4⁺T cells (B,E), B cells (C,F) and CD8⁺T cells (D,G) are depicted. (H,I) Expression of CD69 and CD25 was analyzed in CD4⁺T cells in (B) and the percentage of CD69⁺CD25⁻ cells among total CD4⁺T cells were calculated. Data were pooled from two independent experiments with similar results and represented as mean ± SEM. Each pointrepresents one mouse. See also Figure S5.

Figure 5. CD301b⁺DDC requirement for activation of CD4⁺T cells in response to Th1- and Th2-type adjuvants

As in Figure 4, DT-treated mice were immunized in the right footpad with OVA and alum (A–C) or OVA and CpG 2216 (D–F). Popliteal LNs were harvested on day 3. The total LN cellularity (A,D), the number of CD4⁺T cells (B,E) and the percentage of CD69⁺CD25⁻ cells in total CD4⁺T cells (C,F) are shown. Data were pooled from two independent experiments with similar results and represented as mean ± SEM. Each point represents one mouse.

Figure 6. Requirement of CD301b⁺DDCs for the optimal screening for antigen-specific CD4⁺ T cells upon immunization with papain

Mgl2DTR mice were adoptively transferred with CFSE-labeled OVA-specific naïve OT-II CD4⁺ T cells, and treated with DT or PBS. One day later, the mice were immunized with OVA and papain in the footpad. The draining and non-draining LNs were harvested four days after immunization. (A) Dilution of CFSE in OT-II cells. (B) The number of endogenous polyclonal CD4⁺T cells per LN. (C) The number of OT-II cells per LN. (D) The percentage of undivided CFSE^hi cells among OT-II cells. Data were pooled from two independent experiments with similar results and represented as mean ± SEM. Each point represents one mouse.

Figure 7. Requirement of CD301b⁺DDCs for the papain- and hookworm-induced Th2 cell differentiation

(A–C) Mgl2DTR mice were adoptively transferred with CFSE-labeled OT-II cells and treated with DT or PBS as in Figure 6. (A) The OT-II cells were subdivided based on the number of divisions as shown in Figure 6A. Mean fluorescent intensity of indicated markers in OT-II cells are depicted against the number of cell divisions. The data are representative of two independent experiments and shown as mean ± SEM. n = 3 for each time-point. (B,C) The draining popliteal LNs and spleen were harvested on day 4 (B) or day 8 (B,C) post-immunization and re-stimulated in vitro with PMA and ionomycin for intracellular cytokine staining in gated OT-II cells. (D-G) Mgl2DTR mice were treated with either PBS or DT every 3 days starting at day −1. On day 0, mice were subcutaneously infected with N. brasiliensis at the tail base. At day 5 (D) and day 13 (E and F), indicated LNs were collected and stained for IL-4 following restimualtion with PMA and ionomycin (D) or for Tfh cell markers PD-1 and CXCR5 and germinal center B cell markers CD95 and GL7 without restimulation (E and F). Total CD4⁺ T (D and E) and B (F) cells are shown. Sera were harvested before infection (day 0) or on day 13 and parasite-specific antibody was detected by ELISA (G). Data were pooled from two independent experiments with similar results and represented as mean ± SEM. See also Figures S6 and S7.