Shili Wu

Cell penetrating recombinant Foxp3 protein enhances Treg function and ameliorates arthritis.

Foxp3 is the master transcription factor for T regulatory (Treg) cell differentiation and function. This study aimed to test the therapeutic potential of cell penetrating recombinant Foxp3 protein in arthritis. Recombinant Foxp3 protein was fused to a cell penetrating polyarginine (Foxp3-11R) tag to facilitate intracellular transduction. In vitro Foxp3-11R treated CD4(+) T cells showed a 50% increase in suppressive function compared with control protein treated cells. Severity of arthritis in Foxp3-11R treated mice was significantly reduced compared with those treated with a control protein. CD4(+) T cells of lymph nodes and spleen from Foxp3-11R treated mice showed increased levels of Foxp3 expression compared with those of a control protein treated. These results demonstrated that Foxp3-11R can enhance T cell suppressive function and ameliorate experimental arthritis and suggest that cell penetrating recombinant Foxp3 is a potentially useful agent in therapy of arthritis.

Streptavidin Suppresses T Cell Activation and Inhibits IL-2 Production and CD25 Expression

Streptavidin is widely used as a detection tool in biology research because of its high affinity and specificity binding to biotin. Biotin-streptavidin system has also been explored for detection of infection and tumor in clinical medicine. Here, we show immunosuppressive property of streptavidin on T cell activation and proliferation. Upon CD3 and CD28 stimulation, CD4(+) T cells produce interleukin 2 (IL-2) and express IL-2 receptor α chain (CD25). Addition of streptavidin in T cell culture suppressed IL-2 synthesis and CD25 expression with no cytotoxicity. The immunosuppressive effect of streptavidin was reversed by excessive biotin. Conjugated to a single chain anti-CD7 variable fragment (scFvCD7), streptavidin was directly delivered to T cells and showed substantially more profound suppressive effect on T cell activation. These results suggest that streptavidin could potentially be used as a novel immunomodulator.

Regeneration of hyaline-like cartilage in situ with SOX9 stimulation of bone marrow-derived mesenchymal stem cells

Microfracture, a common procedure for treatment of cartilage injury, induces fibrocartilage repair by recruiting bone marrow derived mesenchymal stem cells (MSC) to the site of cartilage injury. However, fibrocartilage is inferior biomechanically to hyaline cartilage. SRY-type high-mobility group box-9 (SOX9) is a master regulator of chondrogenesis by promoting proliferation and differentiation of MSC into chondrocytes. In this study we aimed to test the therapeutic potential of cell penetrating recombinant SOX9 protein in regeneration of hyaline cartilage in situ at the site of cartilage injury. We generated a recombinant SOX9 protein which was fused with super positively charged green fluorescence protein (GFP) (scSOX9) to facilitate cell penetration. scSOX9 was able to induce chondrogenesis of bone marrow derived MSC in vitro. In a rabbit cartilage injury model, scSOX9 in combination with microfracture significantly improved quality of repaired cartilage as shown by macroscopic appearance. Histological analysis revealed that the reparative tissue induced by microfracture with scSOX9 had features of hyaline cartilage; and collagen type II to type I ratio was similar to that in normal cartilage. This short term in vivo study demonstrated that when administered at the site of microfracture, scSOX9 was able to induce reparative tissue with features of hyaline cartilage.