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Indian Journal of Dermatology, Venereology and Leprology
Medknow Publications on behalf of The Indian Association of Dermatologists, Venereologists and Leprologists (IADVL)
ISSN: 0378-6323 EISSN: 0973-3922
Vol. 74, Num. 2, 2008, pp. 169-169
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Indian Journal of Dermatology, Venereology and Leprology, Vol. 74, No. 2, March-April, 2008, pp. 169
Letter To Editor
Vitiligo, psoriasis and imiquimod: Fitting all into the same pathway
Eapen BellRaj
Consultant dermatologist, Kaya Skin Clinic, Dubai
Correspondence
Address:Kaya
Skin
Clinic,
Dubai,
webmaster@dermatologist.co.in
Code Number: dv08068
Related articles: dv07159, dv08069
Sir,
I read with interest the letter describing imiquimod-induced vitiligo-like depigmentation. [1] There are other similar case reports [2],[3] and 68 reports of pigmentary changes related to imiquimod use listed by FDA. [4] The most widely accepted theory is that imiquimod activates the cell-mediated arm of the immune system via the stimulation of multiple pro-inflammatory cytokines which up-regulates a Type-1 cell response (Th1) that unmasks an innate predilection for the development of vitiligo. [5]
The mode of action of imiquimod involves activation of Toll-like receptors (TLR) 7 and 8, which initiates a signaling cascade leading to the production of pro-inflammatory cytokines like IFN-α and TNF-α. However, TLR 7 and 8 also initiates ubiquitin-mediated proteolysis and apoptosis through the myeloid differentiation factor 88-dependent pathway as evident from the pathway map [6] hsa04620 available from KEGG. [7] In a previous letter to IJDVL , I presented the genomic evidence for ubiquitin-mediated melanocyte-specific apoptotic process in vitiligo. [8] Hence, the ubiquitin-mediated proteolysis may be important in the pathogenesis of vitiligo-like lesions following treatment with imiquimod.
A Th1 type response with increased TNF-α is vital in the pathogenesis of psoriasis. [9] Hence, it is hardly surprising that there are several reports of imiquimod-induced psoriasis. [10],[11],[12],[13] Psoriasis is a proliferative disorder while vitiligo is an apoptotic disorder. It is interesting to note that these disparate conditions converge at a fundamental pathway level.
References
| 1. |
Senel E, Seckin D. Imiquimod-induced vitiligo-like depigmentation. Indian J Dermatol Venereol Leprol 2007;73: 423. Back to cited text no. 1 [BIOLINE] [PUBMED] [FULLTEXT] |
| 2. | Stefanaki C, Nicolaidou E, Hadjivassiliou M, Antoniou C, Katsambas A. Imiquimod-induced vitiligo in a patient with genital warts. J Eur Acad Dermatol Venereol 2006;20:755-756. Back to cited text no. 2 [PUBMED] [FULLTEXT] |
| 3. | Al-Dujaili Z, Hsu S. Imiquimod-induced vitiligo. Dermatol Online J 2007;13:10. Back to cited text no. 3 |
| 4. | Mashiah J, Brenner S. Possible mechanisms in the induction of vitiligo-like hypopigmentation by topical imiquimod. Clin Exp Dermatol 2008;33:74-76. Back to cited text no. 4 [PUBMED] [FULLTEXT] |
| 5. | Nouri K, Busso M, Machler BC. Vitiligo associated with alpha-interferon in a patient with chronic active hepatitis C. Cutis 1997;60:289-290. Back to cited text no. 5 [PUBMED] |
| 6. | Kawai T, Akira S. TLR signaling. Semin Immunol 2007;19:24-32. Back to cited text no. 6 [PUBMED] [FULLTEXT] |
| 7. | Aoki-Kinoshita KF, Kanehisa M. Gene Annotation and Pathway Mapping in KEGG. Methods Mol Biol 2007;396:71-92. Back to cited text no. 7 [PUBMED] |
| 8. | Eapen BR. VIT1 gene and vitiligo. Indian J Dermatol Venereol Leprol 2004;70:184-185. Back to cited text no. 8 [PUBMED] [FULLTEXT] |
| 9. | Nickoloff BJ, Nestle FO. Recent insights into the immunopathogenesis of psoriasis provide new therapeutic opportunities. J Clin Invest 2004;113:1664-1675. Back to cited text no. 9 [PUBMED] [FULLTEXT] |
| 10. | Fanti PA, Dika E, Vaccari S, Miscial C, Varotti C. Generalized psoriasis induced by topical treatment of actinic keratosis with imiquimod. Int J Dermatol 2006;45:1464-1465. Back to cited text no. 10 [PUBMED] [FULLTEXT] |
| 11. | Gilliet M, Conrad C, Geiges M, Cozzio A, Thurlimann W, Burg G, et al . Psoriasis triggered by toll-like receptor 7 agonist imiquimod in the presence of dermal plasmacytoid dendritic cell precursors. Arch Dermatol 2004;140:1490-1495. Back to cited text no. 11 |
| 12. | Rajan N, Langtry JA. Generalized exacerbation of psoriasis associated with imiquimod cream treatment of superficial basal cell carcinomas. Clin Exp Dermatol 2006;31:140-141. Back to cited text no. 12 [PUBMED] [FULLTEXT] |
| 13. | Wu JK, Siller G, Strutton G. Psoriasis induced by topical imiquimod. Australas J Dermatol 2004;45:47-50. Back to cited text no. 13 [PUBMED] [FULLTEXT] |
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