Introduction
Psoriasis is a chronic,
immune-mediated skin disease that can be accompanied by joint
involvement. For its high prevalence and the complexity of causative
mechanisms, psoriasis has caused great concern worldwide [1]. Its
typical clinical manifestations are scales, erythema, and epidermal
thickening. Currently, it is well recognized that psoriasis results from
the complex interaction between keratinocytes and immune cells [2].
Many inflammatory factors (e. g. TNF- α, IL-1 β, IL-23, and IL-12)
secreted by Th17 cells, Th1 cells, and keratinocytes played crucial
effects in their pathogenesis [3]. A growing body of evidence
suggests that psoriasis is closely linked to multiple co-morbidities,
such as systemic inflammation and cardiovascular comorbidity [4].
Therefore, psoriasis has gained significant attention worldwide.
However, there are no effective measures to achieve a cure for
psoriasis.
Curcumin is a polyphenolic compound purified and isolated from Curcuma
longa. Since ancient times, turmeric had been considered an herbal
remedy for the treatment of skin and gastrointestinal disorders [5].
Now, it is clear that its widespread use in medicine stems from its many
properties, such as antioxidant, anti-inflammatory, anti-proliferative,
anti-cancer and anti-bacterial effects [6]. It had been demonstrated
that curcumin can reduce various inflammatory factors such as TNF-α,
IFN-γ, IL-22 and IL-23 in mouse serum, which are closely involved in the
pathogenic mechanism of psoriasis [7]. Meanwhile, curcumin was also
considered as a protective compound that can regulate the intestinal
microflora. Currently, increasing evidence had found that gut microbes
were potentially involved in regulating the progression of a variety of
diseases closely related to inflammation, such as psoriasis, psoriatic
arthritis, inflammatory bowel diseases (IBD) [8, 9].
To further confirm our speculation, we found that curcumin could
significantly improve the IMQ-induced mouse model, and reduce the
expression of multiple pathogenic factors in its skin lesions, such as
TNF- α, IL-17, IL-1 β, etc. Furthermore, we analyzed the changes of
intestinal microbiota in mice after curcumin treatment. By using 16s
rRNA technology, this study investigated whether curcumin could exert
its therapeutic effect in psoriasis, which was in relation to the
regulation of intestinal flora.