Abstract
Psoriasis is mainly caused because of inappropriate immune responses in the epidermis. Rice (Oryza sativa L.: SRNC05053-6-2) consists of anthocyanin, which exhibits strong antioxidative and anti-inflammatory properties. This study aimed to evaluate the role of this black-coloured rice crude extract in alleviating the symptoms of psoriasis using human psoriatic artificial skin and an imiquimod-induced rat psoriasis model. Psoriasis-related genes, cytokines and chemokines were examined; in addition, the antioxidative and anti-inflammatory properties and the immunohistopathological features of this condition were studied. The results showed that the rice extract reduced the severity of psoriasis by (1) decreasing the epidermal thickness, acanthosis, hyperkeratosis, epidermal inflammation and degree of apoptosis induction via caspase-3, (2) increasing the expression levels of anti-inflammatory cytokines (IL-10 and TGF-β), (3) reducing the levels of pro-inflammatory cytokines (IL-6, IL-8, IL-20, IL-22 and TNF-α), chemokines (CCL-20) and anti-microbial peptides (psoriasin and β-defensin), (4) enhancing the antioxidative property (Nrf-2), (5) downregulating the levels of psoriasis-associated genes (psoriasin, β-defensin, koebnerisin 15L and koebnerisin 15S) and (6) upregulating the levels of psoriasis-improving genes (caspase-14, involucrin and filaggrin). Thus, the extract appears to exert therapeutic effects on psoriasis through its antioxidative and immunomodulatory properties.
Highlights
Psoriasis is mainly caused because of inappropriate immune responses in the epidermis
A noncontagious chronic skin condition characterised by the excessively rapid proliferation of keratinocytes, is a common T cell-mediated inflammatory skin disease; it is associated with autoimmune responses that mainly attack the target cells in the skin, keratinocytes and melanocytes, leading to cellular hyperplasia and post-inflammatory hyperpigmentation, respectively[1,2,3,4,5]
The pathogenesis of psoriasis mainly involves the imbalance of epidermal immune responses, which is divided into four stages: initialisation, innate immune response, adaptive immune response and amplification loop[7]
Summary
Psoriasis is mainly caused because of inappropriate immune responses in the epidermis. Dendritic cells are stimulated into the maturation stage and play a pivotal role in mediating the innate immune response by secreting several cytokines, such as transforming growth factor (TGF)-β, tumour necrotic factor (TNF)-α and interleukin (IL)-6 These cytokines initiate T cell-mediated adaptive immune responses through Th-17, Th-1 and Th-22 systems and lead to the increased production of IL-17A, IL-17F, IL-22, IL-21, TNF-α and Immunology, Faculty of Tropical Medicine, Mahidol University, Ratchawithi Road, Ratchathewi, Bangkok 10400, Thailand. The present study aimed to evaluate the efficacy of O sativa L.: SRNC05053-6-2 extract in treating psoriasis using in vitro (full-thickness three-dimensional reconstituted human skin psoriasis) and in vivo (imiquimod-induced rat psoriasis) models Several approaches, such as histopathology, immunohistochemistry, electron microscopy, Bio-Plex Multiplex immunoassay and quantitative reverse transcription-polymerase chain reaction (qRT-PCR), were used to determine the improvement criteria, which were based on the pathology and the levels of the cytokines, chemokines and genes related to psoriasis
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