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Published on: February 9, 2011
Persistence of Staphylococcus aureus colonization on the skin of NC/Nga mice
Yuki Hashimoto1, Yoshie Kaneda, Toshi Akashi
1Pharmacology Laboratory, Medical Research Laboratories, Taisho Pharmaceutical Co., Ltd., 1-403, Yoshino-cho, Kita-ku, Saitama-city, Saitama 331-9530, Japan. yuki.hashimoto@po.rd.taisho.co.jp
Background:
Colonization of Staphylococcus aureus (S. aureus) on skin is one factor which can worsen atopic dermatitis (AD). The reduction of bacterial colonization in these lesions was reported to be effective for the treatment of subjects with AD. NC/Nga mice are recognized to be a model of AD.
Objective:
We examined the susceptibility of S. aureus colonization on the skin in NC/Nga mice, as compared with findings in BALB/c mice.
Methods:
The number of S. aureus on the skin was counted and serum corticosterone, serum interferon-gamma (IFN-gamma) and interleukin (IL)-12 levels were measured. The effects of dexamethasone on number of S. aureus on the skin and serum IFN-gamma and interleukin IL-12 levels were also examined.
Results:
The number of S. aureus increased in parallel with the severity of the dermatitis in these mice, and the remaining number of S. aureus on the skin after topical treatment of S. aureus suspension was higher than that in BALB/c mice. Serum IFN-gamma and IL-12 concentrations in NC/Nga mice were lower than in BALB/c mice, and the circadian variations of serum corticosterone concentrations in NC/Nga mice tended to reveal higher levels compared with the circadian variations in BALB/c mice. Continuous administration of dexamethasone inhibited the elimination of S. aureus from skin surfaces of BALB/c mice. Serum IFN-gamma and IL-12 concentrations in dexamethasone-treated BALB/c mice were lower than those in vehicle-treated BALB/c mice.
Conclusion:
Our data support the notion that high levels of circadian variations of endogenous glucocorticoid lead to a lack of protection against bacteria and a persistence of S. aureus colonization on the skin in NC/Nga mice.
Insights
NC/Nga mice show increased Staphylococcus aureus (S. aureus) colonization, linked to atopic dermatitis severity. High corticosterone levels in these mice impair bacterial clearance, unlike in BALB/c mice.
Area of Science:
- Immunology
- Microbiology
- Dermatology
Background:
- Staphylococcus aureus (S. aureus) colonization exacerbates atopic dermatitis (AD).
- Reducing bacterial load in AD lesions can improve treatment outcomes.
- NC/Nga mice serve as a relevant animal model for studying AD.
Purpose of the Study:
- To compare S. aureus skin colonization susceptibility between NC/Nga and BALB/c mice.
- To investigate the role of immune markers and corticosterone in S. aureus persistence.
- To evaluate the impact of dexamethasone on bacterial load and immune responses.
Main Methods:
- Quantified S. aureus skin colonization in NC/Nga and BALB/c mice.
- Measured serum corticosterone, interferon-gamma (IFN-γ), and interleukin-12 (IL-12) levels.
- Assessed the effects of dexamethasone on bacterial counts and immune markers.
Main Results:
- S. aureus colonization correlated with dermatitis severity in NC/Nga mice.
- NC/Nga mice exhibited higher S. aureus persistence and lower serum IFN-γ and IL-12 levels compared to BALB/c mice.
- Elevated corticosterone circadian variations were observed in NC/Nga mice; dexamethasone impaired S. aureus clearance in BALB/c mice.
Conclusions:
- High circadian variations in endogenous glucocorticoids contribute to impaired bacterial defense and persistent S. aureus colonization in NC/Nga mice.
- These findings highlight a potential mechanism linking stress hormones, immune dysfunction, and bacterial susceptibility in AD models.
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