There is strong evidence for an autoimmune etiology of alopecia areata. Interleukin-17A ( IL-17A ) is a Th17 proinflammatory cytokine that has been linked to the pathogeneses of diverse autoimmune and inflammatory diseases.
A study has measured serum IL-17A in patients with alopecia areata and has studied associations between IL-17A levels and severity of alopecia areata, duration, and age of onset, and patient gender and age.
The study enrolled 39 patients with has studied and 37 healthy control subjects. Scalp involvement was assessed using the Severity of Alopecia Tool ( SALT ), and clinical disease severity was determined.
Serum IL-17A was measured using ELISAs.
Serum IL-17A was significantly higher in patients with alopecia areata than in control subjects ( P less than 0.001 ).
Correlations between serum IL-17A and gender, disease duration, SALT score, and disease severity were non-significant.
Serum IL-17A was significantly higher in patients aged less than or equal to 30 years than in patients aged more than 30 years ( P = 0.045 ).
Age and serum IL-17A were significantly negatively correlated in patients with alopecia areata ( rs = -0.363, P = 0.023 ) but not in control subjects ( rs = -0.294, P = 0.077 ).
Patients with juvenile-onset alopecia areata had significantly higher IL-17A levels than those with maturity-onset disease ( P = 0.034 ).
There was a significant negative correlation between age at disease onset and serum IL-17A ( rs = -0.349, P = 0.029 ).
In conclusion, it is possible that IL-17A plays a role in the pathogenesis of alopecia areata. Serum IL-17A may be influenced by patient age and age of onset of alopecia areata but does not seem to influence disease severity. ( Xagena )
El-Morsy EH et al, Int J Dermatol 2015; Epub ahead of print