Expression of Antimicrobial Peptides

15 Jan
2011

INTRODUCTION

Atopic dermatitis (AD) is a highly pruritic recurring inflammatory skin disease. It can be ex­acerbated by bacterial, viral, and fungal infections. In fact, many AD patients suffered from recurrent infections of skin lesions. Especially, Staphylococcus aureus (S. aureus) is found in more than 90% of AD skin lesions, but in only 5% of normal subjects. The high frequency of skin infection in AD may be due to impairment of immune system, such as am- timicrobial lipids, peptides, toll-like receptors and chemokines. Among them, Ong and co-workers have shown that the levels of AMPs were dramatically suppressed in AD’. AMPs are small peptides produced by keratinocytes in the hostskin. A number of endogenous AMPs have been shown to play an integral part in innate immunity. They exhibit potent killing of a broad range of micro-organisms, including gram-negative and gram- positive bacteria, fungi, and viruses. The lowered AMPs may explain the susceptibility of patients in AD to skin infections.

Recently there were some reports why the expressions of AMPs were decreased in AD. Leung et al. reported that increased IL-10 expression accounts for reduced AMPs production in AD. Ong et al reported that excess of T helper 2(TH2) cytokines may underlie the deficient AMP ex­pression. Elias et al suggested the hypothesis that the elevated stratum corneum pH in AD increased activity of serine protease (SP), which have a role in degradation of AMPs. The skin has been known to have an acidic surface that is thought to play a key role in preventing infection. However, the atopy skin displays a neutral pH because of disrupted permeability barrier. pH influences barrier function directly through its effects on membrane bilayer organization and secondarily through its regulation of extracellular lipid processing and SP signaling’. Increased SP activity due te neutral pH could reduce expressions of AMPs.
Our hypothesis is that permeability barrier disrup­tion could lead to antimicrobial barrier dysfunction. The assessment of epidermal permeability barrier function, we were performed measurements of tran- sepidermal water loss(TEWL), which have been presented to provide information about status of permeability barrier under either normal, experi­mentally perturbed, or diseased conditions. vardenafil 20 mg

In this study, we have examed the level of ex­pression of AMPs according to changes TEWL levels in AD patients. Through these results, we evaluated the relationship between permeability barrier and antimicrobial peptide barrier in AD.

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