Psoriasis experimental model

Nitric oxide has a role in both acute and chronic inflammation. NOS-3 is involved in the vasodilation associated with acute inflammation. In experimental models of acute inflammation, inhibitors of NOS-3 have a dose-dependent protective effect, suggesting that nitric oxide promotes edema and vascular permeability. Nitric oxide has a detrimental effect in chronic models of arthritis dietary L-arginine supplementation exacerbates arthritis whereas protection is seen with NOS-2 inhibitors. Psoriasis lesions, airway epithelium in asthma, and inflammatory bowel lesions in humans all demonstrate elevated levels of nitric oxide and NOS-2. Synovial fluid from patients with arthritis contains increased oxidation products of nitric oxide, particularly peroxynitrite. 

Finally, la,25-dihydroxyvitamin Dj is used to treat psoriasis, and patients can develop resistance. An experimental model for therapy involves enhancement of the endogenous production of la,25-dihydroxyvitamin Dj by gene therapy. ... 

As described previously, one can induce dry, scaly skin, which shows features very similar to dermatitis such as atopic dermatitis and psoriasis. Use of this experimentally induced dry skin should enable the discovery of a new clinical methodology to cure or care for skin problems. Recently, several excellent in vitro skin models have been reported. Although they are also very useful models for the study of cutaneous metabolism, their function and microstructure are still different from those of intact skin. On the other hand, the mechanisms underlying abnormal desquamation, that is, scaling in the dry skin such as atopic dermatitis, are not completely known. Sato et al. reported55 the inhibition of protease in the SC induced scale without affecting epidermal mitosis. This result seems to be no direct relationship between skin surface appearance and epidermal proliferation. However, decline of SC barrier function induced epidermal hyperplasia, as described earlier.30 The loss of water content from SC also induced epidermal DNA synthesis.30 Further mechanistic studies on each of the dry skin features are required. 

Cyclic Nucleotides in Psoriasis - In 1971 Voorhees and Duell proposed the first working model of a potentially deranged cyclic AMP system in psoriasis. 13 The model was based on the fact that three characteristic features of the lesional epidermis of psoriasis are glycogen accumulation,8 decreased terminal differentiations and increased proliferation.14 In other tissues and experimental systems, cyclic AMP was capable of reversing... 

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