Toll-like receptor 2 is important for the T_H1 response to cutaneous sensitization

TLR2 mRNA expression after skin tape stripping and painting with OX. Quantitative PCR analysis of TLR2 mRNA expression in mouse skin after tape stripping (n = 5; A) or application of 2% OX in ethanol to shaved skin (n = 4; B) is shown. Results were normalized for glyceraldehyde-3-phosphate dehydrogenase expression and expressed as fold induction compared with time 0. Values are presented as the mean ± SD. ^∗P < .05.

Impaired epidermal thickening and IFN-γ mRNA expression but normal cellular infiltration and T_H2 cytokine production in OVA-sensitized skin of TLR2^−/− mice. A, Representative skin histology (original magnification ×200). B, Skin-infiltrating CD4⁺ T cells and eosinophils. C, Quantitative PCR analysis of mRNA levels of IL-4, IL-15, and IL-13 and IFN-γ. n = 6-7. ^∗P < .05, ^∗∗P < .01, and ^∗∗∗P < .001. SAL, Saline; KO, knockout.

Impaired T_H1 systemic response to epicutaneous sensitization with OVA in TLR2^−/− mice. A, Cytokine secretion by splenocytes in response to OVA stimulation in vitro. B, Serum levels of OVA-specific immunoglobulin isotypes. n = 6-7. ^∗P < .05, ^∗∗P < .01, and ^∗∗∗P < .001. SAL, Saline; KO, knockout.

Impaired contact hypersensitivity in TLR2^−/− mice. A, Ear swelling in sensitized mice challenged with OX hapten. Results represent the difference in thickness between hapten- and vehicle-challenged ears (n = 10). B, Representative ear skin histology at 24 hours after challenge (original magnification ×200). C and D, IL-4 (Fig 4, C) and IFN-γ (Fig 4, D) mRNA expression as fold induction in hapten-challenged over vehicle-challenged ears. ^∗P < .05, ^∗∗P < .01, and ^∗∗∗P < .0001. KO, Knockout.

Impaired OX-specific IgG2a response in TLR2^−/− mice. Serum anti-OX IgG1 and IgG2a levels in mice sensitized and challenged with OX. Serum was taken 24 hours after the challenge. ^∗P < .05, ^∗∗P < .01, and ^∗∗∗P < .001. KO, Knockout.

Impaired capacity of TLR2^−/− DCs to drive a T_H1 response. Proliferation (A) and secretion of IL-4 (B), IL-13 (C), and IFN-γ (D) by CD4⁺ OTII T cells stimulated with OVA_323-339 peptide in the presence of CD11c⁺ splenic DCs derived from WT and TLR2^−/− mice. Data are representative of 3 experiments. ^∗P < .05 and ^∗∗P < .01. ³H-Td, Tritiated thymidine; KO, knockout.

CCL17/thymus and activation-regulated (TARC) chemokine (A) and CCL11/eotaxin-1 (B) mRNA expression in OVA-sensitized skin of TLR2^−/− mice (n = 5-6). ^∗P < .05, ^∗∗P < .01, and ^∗∗∗P < .001. SAL, saline; KO, knockout.