Ann Dermatol.  2011 Nov;23(4):468-473.

IL-31 Serum Protein and Tissue mRNA Levels in Patients with Atopic Dermatitis

• Kim S
• Kim HJ
• Yang HS
• Kim E
• Huh IS
• Yang JM

Abstract

BACKGROUND
Severe pruritus is the primary symptom in atopic dermatitis (AD). Recently, the novel cytokine IL-31 has been implicated in the itching associated with AD.
OBJECTIVE
We performed this study to determine whether IL-31 serum levels are elevated in AD patients and to better characterize the relationship between serum IL-31 level and other established laboratory parameters.
METHODS
We recruited 55 AD patients, 34 with allergic type AD and 21 with non-allergic type AD, and 38 healthy, non-atopic controls. We checked the laboratory values, severity score, and serum IL-31 levels in all patients and controls, and IL-31 mRNA levels in lesion skin were measured in 13 subjects with AD and in four controls.
RESULTS
AD patients displayed significantly higher levels of serum IL-31 that were associated with serum IgE, disease severity, and subjective itch intensity. In AD patients, IL-31 mRNA levels from the lesional skin samples also correlated with serum IL-31 level.
CONCLUSION
IL-31 is likely one of the many mediators inducing inflammation and pruritus in AD. Although our limited sample size prevents us from making any definitive conclusions, our data demonstrate a strong correlation between IL-31 mRNA level and serum IL-31 protein level, which has never been reported before. Moreover, we found correlations between serum IL-31 level and serum IgE, eosinophil cationic protein, disease severity, and subject itch intensity in certain degrees in AD patients.

Keyword

Atopic dermatitis; IL-31 mRNA; Itching; SCORAD; Serum IL-31

MeSH Terms

Dermatitis, Atopic
Eosinophil Cationic Protein
Humans
Immunoglobulin E
Inflammation
Pruritus
RNA, Messenger
Sample Size
Skin
Eosinophil Cationic Protein
Immunoglobulin E
RNA, Messenger

Figure

• 

  Fig. 1 IL-31 serum levels in patients with extrinsic and intrinsic types of AD versus those of non-atopic controls. AD: atopic dermatitis, ADe: allergic or extrinsic type of AD, ADi: non-allergic or intrinsic type of AD.

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  Fig. 2 (A) RT-PCR analysis of IL-31 expression using RNA extracted from skin biopsies. This analysis showed an increase in IL-13 mRNA in some atopic patients (1~13). (B) The band intensity was quantified with ImageJ software (NIH), and the percentages were the ratio of optical intensity normalized to the GAPDH signal. The level of IL-31 mRNA in the controls (N1~N4) was undetectable. (C) The IL-31 protein level in the serum from the patients in the RT-PCR experiment. Patients 1~4, 9~12 are ADe and patients 5~8, and 13 are ADi. (D) Boxplot of IL-31/GAPDH mRNA(%) in pruritus score 0~4 and 5~10 levels. RT-PCR: reverse trascriptase polymerase chain reaction, GAPDH: glyceraldehyde-3-phosphate dehydrogenase, ADe: allergic or extrinsic type of AD, ADi: non-allergic or intrinsic type of AD.

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