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A homozygous frameshift mutation in the mouse Flg gene facilitates enhanced percutaneous allergen priming.

Fallon PG, Sasaki T, Sandilands A, Campbell LE, Saunders SP, Mangan NE, Callanan JJ, Kawasaki H, Shiohama A, Kubo A, Sundberg JP, Presland RB, Fleckman P, Shimizu N, Kudoh J, Irvine AD, Amagai M, McLean WH - Nat. Genet. (2009)

Bottom Line: Several low-frequency FLG alleles occur in Europeans and Asians, with a cumulative frequency of approximately 9% in Europe.We demonstrate that topical application of allergen to mice homozygous for this mutation results in cutaneous inflammatory infiltrates and enhanced cutaneous allergen priming with development of allergen-specific antibody responses.These data validate flaky tail as a useful model of filaggrin deficiency and provide experimental evidence for the hypothesis that antigen transfer through a defective epidermal barrier is a key mechanism underlying elevated IgE sensitization and initiation of cutaneous inflammation in humans with filaggrin-related atopic disease.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Medicine, Trinity College Dublin, Ireland.

ABSTRACT
Loss-of-function mutations in the FLG (filaggrin) gene cause the semidominant keratinizing disorder ichthyosis vulgaris and convey major genetic risk for atopic dermatitis (eczema), eczema-associated asthma and other allergic phenotypes. Several low-frequency FLG alleles occur in Europeans and Asians, with a cumulative frequency of approximately 9% in Europe. Here we report a 1-bp deletion mutation, 5303delA, analogous to common human FLG mutations, within the murine Flg gene in the spontaneous mouse mutant flaky tail (ft). We demonstrate that topical application of allergen to mice homozygous for this mutation results in cutaneous inflammatory infiltrates and enhanced cutaneous allergen priming with development of allergen-specific antibody responses. These data validate flaky tail as a useful model of filaggrin deficiency and provide experimental evidence for the hypothesis that antigen transfer through a defective epidermal barrier is a key mechanism underlying elevated IgE sensitization and initiation of cutaneous inflammation in humans with filaggrin-related atopic disease.

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Allergen exposure exacerbates skin inflammation ft/ft mice but not wt/wt or wt/ft animals(a) Representative photomicrographs of skin sections from age- and sex-matched wt/wt, wt/ft and ft/ft mice exposed to OVA or PBS as a vehicle control. Ft/ft mice had diffuse mild acanthosis and marked increases in dermal cell infiltration when cutaneously challenged with OVA, compared to wt/wt and wt/ft mice. (Original magnification x40.)(b). Quantification of numbers of skin infiltrating cells, lymphocytes, eosinophils and mononuclear cells detected per high-power fields (HPF). Cells were counted at on 15–20 HPF (x1,000) on hematoxylin and eosin stained sections of 11–14 wt/wt, wt/ft and ft/ft mice. Data represent the mean; error bars represent standard error of the mean. Student’s t-test, or corrected Welch corrected t-test, was used to determine statistical differences between groups. NS = Non-significant.(c) TEWL analysis of skin of OVA exposed wt/wt, wt/ft and ft/ft mice. Values relate to individual mice and mean bars are shown.
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Figure 4: Allergen exposure exacerbates skin inflammation ft/ft mice but not wt/wt or wt/ft animals(a) Representative photomicrographs of skin sections from age- and sex-matched wt/wt, wt/ft and ft/ft mice exposed to OVA or PBS as a vehicle control. Ft/ft mice had diffuse mild acanthosis and marked increases in dermal cell infiltration when cutaneously challenged with OVA, compared to wt/wt and wt/ft mice. (Original magnification x40.)(b). Quantification of numbers of skin infiltrating cells, lymphocytes, eosinophils and mononuclear cells detected per high-power fields (HPF). Cells were counted at on 15–20 HPF (x1,000) on hematoxylin and eosin stained sections of 11–14 wt/wt, wt/ft and ft/ft mice. Data represent the mean; error bars represent standard error of the mean. Student’s t-test, or corrected Welch corrected t-test, was used to determine statistical differences between groups. NS = Non-significant.(c) TEWL analysis of skin of OVA exposed wt/wt, wt/ft and ft/ft mice. Values relate to individual mice and mean bars are shown.

Mentions: To test allergen priming of the skin in these mice, we used the widely studied and clinically relevant allergen ovalbumin (OVA). OVA or PBS, as a vehicle control, was applied to the shaved abdominal skin of wt/wt, wt/ft and ft/ft mice. (Full protocol in Supplementary Fig. S1a). Cutaneous exposure to OVA did not lead to gross skin lesions in any mice (data not shown). Skin removed from the site of allergen challenge revealed evidence of some edema and non-significant increase in cellular infiltrates but no gross damage or inflammation in either wt/wt or ft/wt mice.(Fig. 4a&b). In contrast, exposure of OVA to the skin of ft/ft mice induced diffuse mild acanthosis, with significant infiltrates of mixed, predominantly lymphocytic inflammatory cells, in addition to eosinophils and mononuclear cells (Fig. 4a&b). Measurement of TEWL at the site of allergen challenge 24 hours after OVA application revealed a significant (P<0.0001) elevation in TEWL of OVA-treated ft/ft mice relative to PBS-treated ft/ft mice, and wt/wt and wt/ft mice (Fig. 4c). Application of OVA to wt/wt or wt/ft caused no alteration in TEWL (Fig. 4c).


A homozygous frameshift mutation in the mouse Flg gene facilitates enhanced percutaneous allergen priming.

Fallon PG, Sasaki T, Sandilands A, Campbell LE, Saunders SP, Mangan NE, Callanan JJ, Kawasaki H, Shiohama A, Kubo A, Sundberg JP, Presland RB, Fleckman P, Shimizu N, Kudoh J, Irvine AD, Amagai M, McLean WH - Nat. Genet. (2009)

Allergen exposure exacerbates skin inflammation ft/ft mice but not wt/wt or wt/ft animals(a) Representative photomicrographs of skin sections from age- and sex-matched wt/wt, wt/ft and ft/ft mice exposed to OVA or PBS as a vehicle control. Ft/ft mice had diffuse mild acanthosis and marked increases in dermal cell infiltration when cutaneously challenged with OVA, compared to wt/wt and wt/ft mice. (Original magnification x40.)(b). Quantification of numbers of skin infiltrating cells, lymphocytes, eosinophils and mononuclear cells detected per high-power fields (HPF). Cells were counted at on 15–20 HPF (x1,000) on hematoxylin and eosin stained sections of 11–14 wt/wt, wt/ft and ft/ft mice. Data represent the mean; error bars represent standard error of the mean. Student’s t-test, or corrected Welch corrected t-test, was used to determine statistical differences between groups. NS = Non-significant.(c) TEWL analysis of skin of OVA exposed wt/wt, wt/ft and ft/ft mice. Values relate to individual mice and mean bars are shown.
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Related In: Results  -  Collection

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Figure 4: Allergen exposure exacerbates skin inflammation ft/ft mice but not wt/wt or wt/ft animals(a) Representative photomicrographs of skin sections from age- and sex-matched wt/wt, wt/ft and ft/ft mice exposed to OVA or PBS as a vehicle control. Ft/ft mice had diffuse mild acanthosis and marked increases in dermal cell infiltration when cutaneously challenged with OVA, compared to wt/wt and wt/ft mice. (Original magnification x40.)(b). Quantification of numbers of skin infiltrating cells, lymphocytes, eosinophils and mononuclear cells detected per high-power fields (HPF). Cells were counted at on 15–20 HPF (x1,000) on hematoxylin and eosin stained sections of 11–14 wt/wt, wt/ft and ft/ft mice. Data represent the mean; error bars represent standard error of the mean. Student’s t-test, or corrected Welch corrected t-test, was used to determine statistical differences between groups. NS = Non-significant.(c) TEWL analysis of skin of OVA exposed wt/wt, wt/ft and ft/ft mice. Values relate to individual mice and mean bars are shown.
Mentions: To test allergen priming of the skin in these mice, we used the widely studied and clinically relevant allergen ovalbumin (OVA). OVA or PBS, as a vehicle control, was applied to the shaved abdominal skin of wt/wt, wt/ft and ft/ft mice. (Full protocol in Supplementary Fig. S1a). Cutaneous exposure to OVA did not lead to gross skin lesions in any mice (data not shown). Skin removed from the site of allergen challenge revealed evidence of some edema and non-significant increase in cellular infiltrates but no gross damage or inflammation in either wt/wt or ft/wt mice.(Fig. 4a&b). In contrast, exposure of OVA to the skin of ft/ft mice induced diffuse mild acanthosis, with significant infiltrates of mixed, predominantly lymphocytic inflammatory cells, in addition to eosinophils and mononuclear cells (Fig. 4a&b). Measurement of TEWL at the site of allergen challenge 24 hours after OVA application revealed a significant (P<0.0001) elevation in TEWL of OVA-treated ft/ft mice relative to PBS-treated ft/ft mice, and wt/wt and wt/ft mice (Fig. 4c). Application of OVA to wt/wt or wt/ft caused no alteration in TEWL (Fig. 4c).

Bottom Line: Several low-frequency FLG alleles occur in Europeans and Asians, with a cumulative frequency of approximately 9% in Europe.We demonstrate that topical application of allergen to mice homozygous for this mutation results in cutaneous inflammatory infiltrates and enhanced cutaneous allergen priming with development of allergen-specific antibody responses.These data validate flaky tail as a useful model of filaggrin deficiency and provide experimental evidence for the hypothesis that antigen transfer through a defective epidermal barrier is a key mechanism underlying elevated IgE sensitization and initiation of cutaneous inflammation in humans with filaggrin-related atopic disease.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Medicine, Trinity College Dublin, Ireland.

ABSTRACT
Loss-of-function mutations in the FLG (filaggrin) gene cause the semidominant keratinizing disorder ichthyosis vulgaris and convey major genetic risk for atopic dermatitis (eczema), eczema-associated asthma and other allergic phenotypes. Several low-frequency FLG alleles occur in Europeans and Asians, with a cumulative frequency of approximately 9% in Europe. Here we report a 1-bp deletion mutation, 5303delA, analogous to common human FLG mutations, within the murine Flg gene in the spontaneous mouse mutant flaky tail (ft). We demonstrate that topical application of allergen to mice homozygous for this mutation results in cutaneous inflammatory infiltrates and enhanced cutaneous allergen priming with development of allergen-specific antibody responses. These data validate flaky tail as a useful model of filaggrin deficiency and provide experimental evidence for the hypothesis that antigen transfer through a defective epidermal barrier is a key mechanism underlying elevated IgE sensitization and initiation of cutaneous inflammation in humans with filaggrin-related atopic disease.

Show MeSH
Related in: MedlinePlus