Histopathological and immunohistochemical findings in aldara psoriatic mice model after topical application of methotrexate loaded gold nanoparticle: a comparative study

Efficacy of synthesized bioconjugate of hydrophilic gold nanoparticles (Au 3MPS) loaded MTX was evaluated by topical applicaction on imiquimod-induced psoriasis like mice model by comparing the epidermal thickness and cell proliferation after treatment with nanoparticle alone versus the bioconjugate. Using 50 mg of 5% Imiquimod on shaved back of 8 weeks C57BL/6 mice model for 6 days resulted psoriasis like inflammation. Mice were divided to 4 groups, topically treated with bio-conjugate or nanoparticle alone for 24 or 48 hours and on day 7 or 8 erythema and scaling were scored from 0 to 4. Mice were euthanized and biopsy to evaluate epidermal thickness by H&E-stain and CD3, CD8 &Ki-67 by immunohistochemical stain. The epidermal thickness was significantly reduced in group treated by the conjugate than by nanoparticle alone. It was 0.322μm ±SEM 0.038 vs 0.707μm ±SEM 0.097 and p<0.001. We noticed reduction in the immunopositive Ki-67 cells with significant p<0.001, plus the decrease in CD3 in MTX -Au3MPS treated group compared to the Au 3MPS treated mice after 24h &48 h in epidermis respectively P<0.05, P<0.001 and in dermis 24h &48 h respectively P<0.001, P<0.05. The decrease in CD8 lymphocyte count after 24h &48 h in epidermis was significant P<0.001, P<0.01 and in dermis 24h &48 h respectively P<0.05, P<0.001. After systematic literature review, this is the first study assessing those parameters in psoriasis model under the cutaneous effect of bio-conjugate of MTX and gold nanoparticles. In addition, the data may contribute to clarify the possibility of enhancing the topical delivery of methotrexate by the aid of gold nanoparticle delivery.