Therapeutic effects of combination using glucosamine plus tacrolimus (FK-506) on the development of atopic dermatitis-like skin lesions in NC/Nga mice

Tacrolimus (FK-506) has been found to exhibit potent inhibitory effects on spontaneously developed dermatitis. We previously showed that glucosamine prevents the development of Atopic dermatitis (AD)-like skin lesions in NC/Nga mice. The aims of our study were to investigate the synergistic therapeutic efficacy of combination of glucosamine plus FK-506 in dermatophagoides farina (Df)-induced AD-like skin lesions in NC/Nga mice and to determine the underlying therapeutic mechanisms. The Df-induced NC/Nga mice with a clinical score of 8 were used for treatment with glucosamine (500 mg/kg) alone, FK-506 (1.0 mg/kg) or in combination. The synergistic effects of combination therapy were evaluated by dermatitis scores, skin histology and immunological parameters such as IgE, Th2-mediated cytokines and chemokines, CD3(+) T cells and CLA(+) T cells. Combined therapy using glucosamine plus FK-506 improved the development of AD-like skin lesions as exemplified by a significant decrease in total skin symptom severity scores. The suppression of dermatitis by combined therapy was accompanied by a decrease in the plasma level of IgE and in the splenic level of IL-5, IL-13, TARC and eotaxin. Histological finding indicated that the dermal infiltration of inflammatory cells including mast cells and eosinophils was greatly reduced. Particularly, immunohistological evaluation reveals a reduction in CD3(+) T cells and CLA(+) cells in the combined therapy. Our findings suggest that combination therapy of glucosamine plus FK-506 was more synergistic efficacy than single-modality treatment with either alone to improve the development of established dermatitis in NC/Nga mice model. This combined immunosuppressive therapy may provide an effective therapeutic strategy for the treatment of AD.