Table_1_GDF15 Regulates Malat-1 Circular RNA and Inactivates NFκB Signaling Leading to Immune Tolerogenic DCs for Preventing Alloimmune Rejection in Heart Transplantation.docx

Recombinant human growth differentiation factor 15 (rhGDF15) affects dendritic cell (DC) maturation. However, whether GDF15 is expressed in DCs and its roles and signaling in DCs remain largely unknown. It is unclear whether GDF15-DCs can induce immune tolerance in heart transplantation (HT). This study aims to understand the impact of endogenous GDF15 on DC's development, function, underlying molecular mechanism including circular RNA (circRNA). This study will also explore GDF15-DC-mediated immune modulation in HT. Bone marrow (BM) derived DCs were cultured and treated to up- or down regulate GDF15 expression. Phenotype and function of DCs were detected. Expression of genes and circRNAs was determined by qRT-PCR. The signaling pathways activated by GDF15 were examined. The impact of GDF15 treated DCs on preventing allograft immune rejection was assessed in a MHC full mismatch mouse HT model. Our results showed that GDF15 was expressed in DCs. Knockout of GDF15 promoted DC maturation, enhanced immune responsive functions, up-regulated malat-1 circular RNA (circ_Malat 1), and activated the nuclear factor kappa B (NFκB) pathway. Overexpression of GDF15 in DCs increased immunosuppressive/inhibitory molecules, enhanced DCs to induce T cell exhaustion, and promoted Treg generation through IDO signaling. GDF15 utilized transforming growth factor (TGF) β receptors I and II, not GFAL. Administration of GDF15 treated DCs prevented allograft rejection and induced immune tolerance in transplantation. In conclusion, GDF15 induces tolerogenic DCs (Tol-DCs) through inhibition of circ_Malat-1 and the NFκB signaling pathway and up-regulation of IDO. GDF15-DCs can prevent alloimmune rejection in HT.

重组人生长分化因子15（rhGDF15）影响树突状细胞（DC）的成熟。然而，GDF15是否在DC中表达及其在DC中的功能与信号传导作用仍鲜为人知。GDF15-DCs是否能诱导心脏移植（HT）中的免疫耐受尚不明确。本研究旨在探究内源性GDF15对DC发育、功能以及包括环状RNA（circRNA）在内的潜在分子机制的影响。此外，本研究还将探讨GDF15-DC介导的心脏移植中的免疫调节作用。通过骨髓（BM）来源的DCs进行培养和处理，以上调或下调GDF15的表达。检测DCs的表型和功能。通过定量逆转录聚合酶链反应（qRT-PCR）确定基因和circRNAs的表达。检查GDF15激活的信号通路。在MHC全不匹配小鼠心脏移植模型中评估GDF15处理后的DCs对同种异体移植物免疫排斥的预防作用。我们的结果显示，GDF15在DCs中表达。GDF15基因敲除促进DC成熟，增强免疫应答功能，上调malat-1环状RNA（circ_Malat 1），并激活核因子κB（NFκB）通路。在DCs中过表达GDF15增加免疫抑制/抑制分子，增强DCs诱导T细胞耗竭，并通过IDO信号通路促进调节性T细胞（Treg）的产生。GDF15利用转化生长因子（TGF）β受体I和II，而非GFAL。给予GDF15处理后的DCs可预防同种异体移植物的排斥反应并诱导移植免疫耐受。总之，GDF15通过抑制circ_Malat-1和NFκB信号通路以及上调IDO，诱导耐受性DCs（Tol-DCs）。GDF15-DCs能预防心脏移植中的同种免疫排斥。