The regulatory T cell effector soluble fibrinogen-like protein 2 induces tubular epithelial cell apoptosis in renal transplantation

Experimental Biology and Medicine (Impact Factor: 2.17). 01/2014; 239(2). DOI: 10.1177/1535370213514921
Source: PubMed


Acute rejection (AR) hinders renal allograft survival. Tubular epithelial cell (TEC) apoptosis contributes to premature graft loss in AR, while the mechanism remains unclear. Soluble fibrinogen-like protein 2 (sFGL2), a novel effector of regulatory T cells (Treg), induces apoptosis to mediate tissue injury. We previously found that serum sFGL2 significantly increased in renal allograft rejection patients. In this study, the role of sFGL2 in AR was further investigated both in vivo and in vitro. The serum level of sFGL2 and the percentage of CD4(+)CD25(+)Foxp3(+) Treg in the peripheral blood were measured in renal allograft recipients with AR or stable renal function (n = 30 per group). The human TEC was stimulated with sFGL2, tumor necrosis factor (TNF)-α, or phosphate buffered saline and investigated for apoptosis in vitro. Apoptosis-associated genes expression in TEC was further assessed. Approval for this study was obtained from the Ethics Committee of Fudan University. Our results showed that the serum level of sFGL2, correlated with Treg in the peripheral blood, was significantly increased in the AR patients. In vitro, sFGL2 remarkably induced TEC apoptosis, with a significant up-regulation of proapoptotic genes, including CASP-3, CASP-8, CASP-9, CASP-10, TRADD, TNFSF10, FADD, FAS, FASLG, BAK1, BAD, BAX, and NF-KB1. However, no significant changes were observed in the expression of antiapoptotic genes, including CARD-18, NAIP, BCL2, IKBKB, and TBK1. Therefore, sFGL2, an effector of Treg, induces TEC apoptosis. Our study suggests that sFGL2 is a potential mediator in the pathogenesis of allograft rejection and provides novel insights into the role of Treg in AR.

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    • "Our serial in vivo and in vitro studies showed that circulating sFGL2 was increased in kidney injuries and contributed to TEC apoptosis [11]. Here, we further investigated the dynamic change of sFGL2 in the kidney and circulation throughout 2-week duration of renal IR injury in a porcine auto-transplantation model. "
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    ABSTRACT: Regulatory T cells (Treg) protect kidney against ischemia reperfusion (IR) injury via suppressing innate immunity, but the mechanism has not been fully clarified. Soluble fibrinogen-like protein 2 (sFGL2), a novel effector of Treg, may affect apoptosis and inflammation. This study investigated the role of sFGL2 in renal IR injury in a porcine kidney auto-transplantation model.Materials and methods: The left kidney was retrieved from mini pigs and infused by University of Wisconsin solution into the renal artery with the renal artery and vein clamped for 24-h cold storage. After the right nephrectomy, the left kidney was auto-transplanted into the right for 2 weeks. 3 pigs were sacrificed at day 2, 5, 7, 10 and 14 post-transplantation respectively. Collected renal tissues and daily blood samples were stored for further analyses. Both serum creatinine and blood urea nitrogen were maximized during day 2 to 5 and followed by a gradual recovery over 2 weeks. The similar pattern were showed in histological damage, myeloperoxidase + cells and apoptosis in the kidney, as well as circulating TNF-alpha and IFN-gamma. Serum sFGL2 presented a fluctuating increase and reached a peak at day 10. The expression of sFGL2 and its receptor FcgammaRIIB as well as Foxp3 and IL-10 in the kidney was notably increased from day 5 to 10. The increased sFGL2 together with FcgammaRIIB during renal recovery after IR injury suggested that sFGL2 might be a potential renoprotective mediator involved in the renal self-repairing and remodeling in this 2-week porcine auto-transplantation model.
    Journal of Translational Medicine 02/2014; 12(1):53. DOI:10.1186/1479-5876-12-53 · 3.93 Impact Factor
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    ABSTRACT: Helix B surface peptide (HBSP), derived from erythropoietin, displays powerful tissue protection during kidney ischemia reperfusion (IR) injury without erythropoietic side effects. We employed cyclization strategy for the first time, and synthesized thioether-cyclized helix B peptide (CHBP) to improve metabolic stability and renoprotective effect. LC–MS/MS analysis was adopted to examine the stability of CHBP in vitro and in vivo. The renoprotective effect of CHBP in terms of renal function, apoptosis, inflammation, extracellular matrix deposition, and histological injury were also detected in vivo and in vitro. Antibody array and western blot were performed to analyze the signal pathway of involvement by CHBP in the IR model and renal tubular epithelial cells. In this study, thioether-cyclized peptide was significantly stable in vivo and in vitro. One dose of 8 nmol/kg CHBP administered intraperitoneally at the onset of reperfusion improved renal protection compared with three doses of 8 nmol/kg linear HBSP in a 48 h murine IR model. In a one-week model, the one dose CHBP-treated group exhibited remarkably improved renal function over the IR group, and attenuated kidney injury, including reduced inflammation and apoptosis. Interestingly, we found that the phosphorylation of autophagy protein mTORC1 was dramatically reduced upon CHBP treatment. We also demonstrated that CHBP induced autophagy via inhibition of mTORC1 and activation of mTORC2, leading to renoprotective effects on IR. Our results indicate that the novel metabolically stable CHBP is a promising therapeutic medicine for kidney IR injury treatment.
    Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease 11/2014; 1842(11). DOI:10.1016/j.bbadis.2014.09.001 · 4.88 Impact Factor
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    ABSTRACT: Background: Fibrinogen-like protein 2 (FGL2) may promote glioblastoma multiforme (GBM) cancer development by inducing multiple immune-suppression mechanisms. Methods: The biological significance of FGL2 expression was assessed using the The Cancer Genome Atlast (TCGA) glioma database and tumor lysates analysis. The therapeutic effects of an anti-Fgl2 antibody and the role of immune suppression regulation by Fgl2 were determined in immune-competent, NOD-scid IL2Rgammanull (NSG), and FcɣRIIB-/- mice (n = 3-18 per group). Data were analyzed with two-way analysis of variance, log-rank survival analysis, and Pearson correlation. All statistical tests were two-sided. Results: In low-grade gliomas, 72.5% of patients maintained two copies of the FGL2 gene, whereas 83.8% of GBM patients had gene amplification or copy gain. Patients with high levels of FGL2 mRNA in glioma tissues had a lower overall survival (P = .009). Protein levels of FGL2 in GBM lysates were higher relative to low-grade glioma lysates (11.48±5.75ng/mg vs 3.96±1.01ng/mg, P = .003). In GL261 mice treated with an anti-FGL2 antibody, median survival was 27 days compared with only 17 days for mice treated with an isotype control antibody (P = .01). The anti-FGL2 antibody treatment reduced CD39(+) Tregs, M2 macrophages, programmed cell death protein 1 (PD-1), and myeloid-derived suppressor cells (MDSCs). FGL2-induced increases in M2, CD39, and PD-1 were ablated in FcɣRIIB-/- mice. Conclusions: FGL2 augments glioma immunosuppression by increasing the expression levels of PD-1 and CD39, expanding the frequency of tumor-supportive M2 macrophages via the FcγRIIB pathway, and enhancing the number of MDSCs and CD39(+) regulatory T cells. Collectively, these results show that FGL2 functions as a key immune-suppressive modulator and has potential as an immunotherapeutic target for treating GBM.
    JNCI Journal of the National Cancer Institute 05/2015; 107(8). DOI:10.1093/jnci/djv137 · 12.58 Impact Factor