CCR4 Ligands (Thymus and Activation-Regulated Chemokine 'TARC / CCL17 and Macrophage-Derived Chemokine 'MDC' / CCL22') as Disease Severity Markers in Atopic Dermatitis Patients

Background: Atopic dermatitis (AD) is a pruritic and chronically relapsing inflammatory skin disease with predominant infiltration of T helper 2 (Th2) cells as a hallmark of the disease.  Th2 lymphocytes express CCR4 receptors. CCR4 ligands (thymus and activation-regulated chemokine 'TARC- CCL17 and macrophage-derived chemokine 'MDC' CCL22 ') direct trafficking and recruitment of Th2 cells into lesional skin in AD. These chemokines appear to be useful inflammatory markers for assessing severity of AD. The objectives were to establish the relationships between TARC , MDC, and clinical picture of AD as disease severity markers. Methodology : This study included 25 patients with AD in addition to 25 age and sex matched healthy subjects as a control group. Patients were classified into mild (n =3), moderate (n =13) and severe (n =9) according to the SCORing AD (SCORAD) index. Serum concentrations of CCR4 ligands were determined from all patients and controls by Enzyme- linked immunosorbent assay (ELISA). CCR4 expression was quantitated by real time RT-PCR Results: A highly significant increase was found in the serum TARC and MDC levels in AD patients compared to controls. There was significant positive correlation of TARC (r= 0.81, p<0.001). and MDC levels (r=0.53, p<0.006) with severity of the disease as determined by SCORing Atopic Dermatitis (SCORAD) score . There was more expression of CCR4 in AD patients than control with statistically significant difference (p<0.001). Conclusion : serum CCR4 ligands may be useful markers for assessing AD severity. Among the adjuvant therapeutic strategies of AD, further attention to these biomarkers will help with the development of novel targeted therapeutics as well as assessment of therapy response