Human umbilical cord blood-derived mesenchymal stem cells ameliorate psoriasis-like skin inflammation in mice

Abstract

Mesenchymal stem cells (MSCs) inhibit the proliferation or activation of lymphocytes, and their inhibitory effects do not require human leukocyte antigen (HLA)-matching because MSCs express low levels of HLA molecules. Therefore, MSCs may be able to regulate immune responses. In this study, we determined whether MSCs could inhibit psoriasis-like skin inflammation in mice. After induction of psoriasis-like skin inflammation using intradermal injection of IL-23 or topical application of imiquimod with or without treatment with MSC, mouse skins were collected, and H&E staining and real-time PCR were performed. IL-23-induced skin inflammation was inhibited when MSCs were injected on day -1 and day 7. The expression of proinflammatory cytokines such as IL-6, IL-17, and TNF-α was inhibited by MSC injection, and the expression of chemokines such as CCL17, CCL20, and CCL27 was also decreased in mouse skin. We also determined whether MSCs could not only prevent but also treat psoriasis-like skin inflammation in mice. Furthermore, in vitro experiments also showed anti-inflammatory effects of MSCs. Dendritic cells which are co-cultured with MSCs suppressed CD4+ T cell activation and differentiation, which are important for the pathogenesis of psoriasis. These results suggest that MSCs could be useful for treating psoriasis.

Keywords: Anti-inflammatory effects; BMDC, bone marrow-derived dendritic cell; IDO, indoleamine 2,3-dioxygenase; IL, interleukin; Mesenchymal stem cells; Psoriasis; Skin inflammation; hUCB-MSC, human umbilical cord blood-derived mesenchymal stem cell.

Figures

Fig. 1

hUCB-MSCs prevent IL-23-induced psoriasis-like skin inflammation in mice. (a) Experimental scheme for the induction of IL-23-induced psoriasis-like skin inflammation and treatment with hUCB-MSCs in mice. (b) H&E staining of mouse ear skin. Bar=200 µm (c) Intradermal injection of IL-23 increased epidermal thickness, and treatment with hUCB-MSCs inhibited the IL-23-mediated increase in epidermal thickness. (d) Percentages of CD11b+, CD11c+, and CD4+ T cells in the skin were determined through flow cytometry. Psoriasis-related pro-inflammatory cytokine gene (e) and chemokine gene (f) expression was measured by real-time PCR. The results shown are representative of three independent experiments. A.U.: Arbitrary Unit. Data are shown as mean±SEM. *P<0.05, **P<0.005.

Fig. 2

hUCB-MSCs treat IL-23-mediated psoriasis-like skin inflammation in mice. (a) Experimental scheme for induction of IL-23-mediated skin inflammation and treatment with hUCB-MSCs in mice. (b) H&E staining of mouse ear skin. Bar=100 µm (c) Epidermal thickness of ear skin was measured at several regions throughout the epidermis of skin section. (d) Psoriasis-related pro-inflammatory cytokine (e) and chemokine (f) gene expression was determined by real-time PCR. A.U.: Arbitrary Unit. Data are shown as mean±SEM. *P<0.05, **P<0.005.

Fig. 3

hUCB-MSCs inhibit imiquimod-induced psoriasis-like skin inflammation in mice. (a) Experimental scheme for imiquimod-induced psoriasis-like skin inflammation and hUCB-MSC treatment. (b) Picture of imiquimod-induced psoriasis-like skin inflammation in mice. hUCB-MSCs ameliorated imiquimod-induced psoriasis-like skin inflammation. (c) H&E staining of mouse back skin. Bar=100 µm (d) Epidermal thickness was increased by imiquimod and subcutaneous injection of hUCB-MSCs reduced the increased epidermal thickness. Epidermal thickness was measured at several regions throughout the skin section. (e) Percentages of immune cells in the skin. (f) Psoriasis-related pro-inflammatory cytokine and (g) chemokine gene expression was determined by real-time PCR. R.E: Relative Expression. A.U.: Arbitrary Unit. Intracellular staining of (h) lymph node cells and (i) spleen cells was performed as described in Materials and Methods section. Data are shown as mean±SEM. *P<0.05, **P<0.005.

Fig. 4

MSC-treated DCs inhibit CD4+ T cell proliferation and differentiation. (a) Proliferation of CD4+ T cells was analyzed with CFSE dilution assay. The results shown are representative of three independent experiments. (b and c) Expressions of signature cytokine and transcription factors were determined by real-time PCR from co-cultured CD4+ T cells with DCs, which were or were not pre-treated with hUCB-MSCs, under Th1, Th2, Th17, or Treg cell conditions. A.U.: Arbitrary Unit. Data are shown as mean ± SEM. *P<0.05, **P<0.005.