Betamethasone Treatment for Atopic Dermatitis in Gut Microbiota Transplanted Mice

Abstract

Gut microbiota composition correlates strongly with essential disease parameters in the oxazolone-induced mouse model for atopic dermatitis. The phenotype of this model can be transferred to germ-free mice with a gut microbiota transplant to achieve high and low responding mice. Therefore, the production of high responding mice through gut microbiota transplantation may be seen as a tool to reduce group sizes or increase power in intervention studies by increasing effect size. We sought to determine whether high responding mice respond to a common treatment in the same way as low responding mice. We hypothesized that while high responding mice would exhibit a higher clinical score than low responding mice before treatment, the clinical parameters would be similar in both groups after betamethasone treatment. Dermatitis was induced with oxazolone in barrier bred Swiss Webster mice, and a high responding and a low responding donor was selected based upon clinical and pathologic scores, as confirmed by monitoring a range of ear tissue cytokines. Feces from these donors were transplanted to pregnant germ-free Swiss Webster dams, and subsequently to their offspring. Although the overall effect of betamethasone on the clinical dermatitis score and ear thickness was rather small, the high responding recipients had significantly higher clinical dermatitis score and ear thickness than the low responding recipients before treatment, and these differences vanished after betamethasone treatment. We conclude that high responding recipients can be treated to a clinical level comparable with the low responding recipients.

Figure 1.

A classic parallel design was used in this study in which dermatitis was induced onto the right ear of 10 barrier-housed Tac:SW mice by sensitizing with a single application of 0.8% OXA solution on day –7 and maintained by challenges with 0.4% OXA solution on day 0, 3, 5, 7, 10, 12, 14, 16, 18 and 20. Based upon the clinical dermatitis score, ear thickness measurement and the histopathologic score one high responding (HR) and one low responding (LR) mouse were selected to be gut microbiota donors. Gut microbiota from the HR and the LR donor mice was orally transferred to germ-free (GF) Tac:SW dams in 2 isolators in their third week of pregnancy and subsequently to their offspring at 1 wk and 3 wk of age. Dermatitis was induced onto the ears of the recipient mice by application of a 0.8% OXA solution at day -7 and with a 0.4% OXA solution on day 0, 3, 5, 7, 10, and 12. The clinical signs were scored, and the ear thickness of the right ear measured, on day -7 and day 21 of the donor mice and on day -7, 7 and 14 of the recipients. The recipients were topically treated with a betamethasone solution on day 7, 8, 9, 10, 11, 12 and 13. The donor mice were euthanized on day 21 and the recipients on day 14 and samples for further analysis were collected.

Figure 2.

The selection of one high responding (HR) and one low responding (LR) gut microbiota (GM) donor Tac:SW mouse after induction of dermatitis with oxazolone. The clinical dermatitis score, ear thickness and the histopathologic score were used to select mouse number 3 as the HR GM donor and mouse number 10 as the LR GM donor. Subsequently cytokine concentrations in ear biopsies from the right ear were measured. Values highlighted in green are <25% percentile and values highlighted in red are >75% percentile. Concentrations written in italics indicate adjusted concentrations below the limit of the detection in the assay. Hyphens (-) represent concentrations not detected in the assay.

Figure 3.

A. Clinical dermatitis score (* P = 0.0439) and ear thickness (* P = 0.0353) in high responding (HR) and low responding (LR) Tac:SW recipient mice before betamethasone treatment. B. Clinical dermatitis score (P = 0.2197), ear thickness (P = 0.2133), histopathologic score (P = 0.1865) and serum IgE (P = 0.3922) in high responding (HR) and low responding (LR) recipients after betamethasone treatment.

Figure 4.

Levels of cytokines related to type 1 and type 2 helper, regulatory, natural killer and cytotoxic t cells, macrophages and neutrophils (A) and T helper cell type 17 related cytokine levels (B) in high responding (HR) and low responding (LR) Tac:SW recipients after betamethasone treatment. Asterisks (*) show significant differences calculated between the LR and HR recipients.

Figure 5.

Comparison of the clinical dermatitis score (A) and ear thickness (B) of the low responding (LR) and the high responding (HR) Tac:SW recipients before and after betamethasone treatment.