Keratinocyte growth factor phage model peptides can promote epidermal cell proliferation without tumorigenic effect

Background Keratinocyte growth factor （KGF） significantly influences epithelial wound healing. The aim of this study was to isolate KGF phage model peptides from a phage display 7-mer peptide library to evaluate their effect on promoting epidermal cell proliferation. Methods A phage display 7-mer peptide library was screened using monoclonal anti-human KGF antibody as the target. Enzyme linked immunosorbent assay （ELISA） was performed to select monoclonal phages with good binding activity. DNA sequencing was done to find the similarities of model peptides. Three-（4,5-dimethylthiazol-2-yl） -2,5-diphenyl tetrazolium bromide （MTT） assay, immunofluorescence assay and quantitative real-time PCR analysis were employed to evaluate the effect of the phage model peptides on epidermal cells. Results Thirty-three out of fifty-eight （56.9%） of the isolated monoclonal phages exhibited high binding activity by ELISA. Ten of fifteen obtained phage model peptides were similar to KGF or epidermal growth factor （EGF）. MTT assay data showed that four （No. 1-4） of the ten phage model peptides could promote epidermal cell proliferation. The expression of keratinocyte growth factor receptor （KGFR） mRNA in the KGF control group and the two phage model peptide groups （No. 1 and No. 2） increased. Expression of c-Fos mRNA and c-Jun mRNA in the KGF control group increased, but did not increase in the four phage model peptide groups （No.1-4）. Conclusion Four phage model peptides isolated from the phage display 7-mer peptide library can safely promote epidermal cell proliferation without tumorigenic effect.

Impaired upregulation of keratinocyte growth factor in injured lungs induced by Pseudomonas aeruginosa in immunosuppressed rats

Background The number of immunosupressed patients has increased in the past decades. Among them Pseudomonas aeruginosa （P. aeruginosa） is one of the leading bacteria for pneumonia that are associated with poor prognosis. However, the pathogenesis of P. aeruginosa pneumonia in immunosupressed patients is not understood completely. Previous reports showed keratinocyte growth factor （KGF） is associated with lung injury in immunocompetent hosts. In this study, we investigated the different reactions of lung injury, lung pathology and KGF expressions in P aeruginosa pneumonia between immunosuppressed and immunocompetent rats. Methods Immunosuppression of male rats was induced by injecting immunosuppressive subcutaneously. Pneumonia was established by instilling P aeruginous tracheally. The immunocompetent rats were the control group. Survival rate, lung histopathology, pulmonary permeability and oedema, KGF mRNA and protein expressions in lungs of both groups were investigated. Results The survival rate of immunosuppressed group was lower than that of immunocompetent group （33.3% vs 83.3%）. After exposure to bacteria, pulmonary permeability and wet/dry ratio in immunosuppressed group were higher than those in immunocompetent group. Pulmonary congestion and haemorrhage were more intensive in immunosuppressed group compared to immunocompetent group. Apoptosis and necrosis were also observed in infected lungs of immunosuppressed rats. Although we detected KGF expressions in lungs of both groups after infection, the expressions of KGF protein and mRNA gene in immunosuppressed group were much lower than in immunocompetent group. Conclusions Compared with immunocompetent group, there was more intensive lung injury in immunosuppressed group. Severe lung injury may contribute to the poor prognosis of pneumonia. KGF expressions of pneumonia in immunosuppressed rats were less than those in immunocompetent ones.

Umbilical cord-derived mesenchymal stem cells regulate thymic epithelial cell development and function in Foxn 1^-/- mice

Thymic microenvironments are essential for the maturation of thymocytes, which can be anatomically compartmentalized into cortical and medullar regions. The absence of the gene encoding the transcription factor forkhead box nl （Foxnl） causes epithelial differentiation to stall in the precursor stage, resulting in the formation of an abnormal thymus. In this study, we used human umbilical cord-derived mesenchymal stem cells （UC-MSCs） to treat Foxn1^-/- mice, and then analyzed the maturation and distribution of thymic epithelial cells in the Foxn1^-/- thymic rudiment and the thymopoiesis of this newly developed rudiment. Our data showed a well-organized cortex-medulla architecture and an obvious improvement in the maturation of thymic epithelial ceils along with the appearance of UEA-1^＋MHCIIhi thymic epithelial cells in the rudiment. We further demonstrated improved thymopoiesis and the enhanced export of mature T cells with increased numbers of regulatory T cells into the peripheral blood. Furthermore, we observed that MSCs can engraft into thymic tissue and express many cytokines or proteins, particularly keratinocyte growth factor （KGF） and CD248, which are essential for thymic development. Collectively, our data identified a new mechanism for MSCs, which may provide a proper microenvironment for the reconstitution and functional maturation of the thymus in Foxn1^-/- mice. Additionally, we elicited additional insights into the therapeutic efficacy of MSCs in several autoimmune diseases.

Modulation of Wnt/β-catenin signaling affects the directional differentiation of hair follicle stem cells

Aim:The differentiation of hair follicle stem cells(HFSCs)into hair follicle cells has potential clinical applications for cutaneous burns.However,the mechanisms regulating the differentiation of HFSCs into hair follicular papilla or epidermal cells are currently not clear.This study investigated the role of the Wnt/β-catenin pathway and its crosstalk with other signaling components during this differentiation process.Methods:Lithium chloride(LiCl,10 mmol/L)and keratinocyte growth factor(KGF,10μg/L)were used to induce HFSC differentiation,validated by immunofluorescence analysis.The mRNA expression ofβ-catenin,adenomatous polyposis coli,glycogen synthase kinase-3β(GSK-3β),axin,and lymphoid enhancer factor-1 after 3,5,7,and 9 days were measured to evaluate the role of the Wnt/β-catenin pathway.Results:During LiCl-induced HFSC differentiation into hair follicle cells,the Wnt/β-catenin signaling pathway was activated and the expression of GSK-3β,a vital component of the degradation compound,was inhibited.This led to increased cytoplasmicβ-catenin expression,nuclear translocation,and subsequent target gene transcription.By contrast,KGF induced the differentiation of HFSCs into epidermal cells and did not affect the expression ofβ-catenin.This data indicates that LiCl and KGF distinctly regulate the differentiation of HFSCs into hair follicle and epidermal cells,respectively.Furthermore,the Wnt/β-catenin signaling pathway is predominantly involved in hair follicle differentiation.Conclusion:these results demonstrate that LiCl can be used to differentiate HFSCs into hair follicle cells in vitro,which has important therapeutic applications for treating patients with cutaneous damage.