The lymph node (LN) is the primary site of alloimmunity activation and regulation during transplantation. Here, we investigated how fibroblastic reticular cells (FRCs) facilitate the tolerance induced by anti-CD40L in a murine model of heart transplantation. We found that both the absence of LNs and FRC depletion abrogated the effect of anti-CD40L in prolonging murine heart allograft survival. Depletion of FRCs impaired homing of T cells across the high endothelial venules (HEVs) and promoted formation of alloreactive T cells in the LNs in heart-transplanted mice treated with anti-CD40L. Single-cell RNA sequencing of the LNs showed that anti-CD40L promotes a Madcam1+ FRC subset. FRCs also promoted the formation of regulatory T cells (Tregs) in vitro. Nanoparticles (NPs) containing anti-CD40L were selectively delivered to the LNs by coating them with MECA-79, which binds to peripheral node addressin (PNAd) glycoproteins expressed exclusively by HEVs. Treatment with these MECA-79–anti-CD40L-NPs markedly delayed the onset of heart allograft rejection and increased the presence of Tregs. Finally, combined MECA-79–anti-CD40L-NPs and rapamycin treatment resulted in markedly longer allograft survival than soluble anti-CD40L and rapamycin. These data demonstrate that FRCs are critical to facilitating costimulatory blockade. LN-targeted nanodelivery of anti-CD40L could effectively promote heart allograft acceptance.
Jing Zhao, Sungwook Jung, Xiaofei Li, Lushen Li, Vivek Kasinath, Hengcheng Zhang, Said N. Movahedi, Ahmad Mardini, Gianmarco Sabiu, Yoonha Hwang, Vikas Saxena, Yang Song, Bing Ma, Sophie E. Acton, Pilhan Kim, Joren C. Madsen, Peter T. Sage, Stefan G. Tullius, George C. Tsokos, Jonathan S. Bromberg, Reza Abdi
Absence of Interferon-γ Receptor (IFNGR) or Signal Transducer and Activator of Transcription 1 (STAT1) signaling in donor cells has been shown to result in reduced acute GVHD induction. In this study, we unexpectedly observed increased activation and expansion of donor lymphocytes in both lymphohematopoietic organs and GVHD target tissues of IFNGR/STAT1-deficient recipient mice, leading to rapid mortality following the induction of GVHD. Lipopolysaccharide (LPS)-matured bone marrow-derived Ifngr1-/-/Stat1-/- dendritic cells (BMDCs) were more potent allogeneic stimulators and expressed increased levels of MHC II and costimulatory molecules. Similar effects were observed in human APCs with knockdown of Stat1 by CRISPR/Cas9 and treatment with a JAK1/2 inhibitor. Furthermore, we demonstrated that the absence of IFNGR/STAT1 signaling in hematopoietic APCs impaired the presentation of exogenous antigens while promoting the presentation of endogenous antigens. In contrast, the indirect presentation of host antigens to donor lymphocytes was defective in IFNGR/STAT1-deficient donor-derived APCs in fully donor chimeric mice. The differential effects of IFNGR/STAT1 signaling on endogenous and exogenous antigen presentation could provide further insight into the roles of the IFN-γ/STAT1 signal pathway in the pathogenesis of GVHD, organ rejection, and autoimmune diseases.
Caisheng Lu, Huihui Ma, Liangsong Song, Hui Wang, Lily Wang, Shirong Li, Stephen M. Lagana, Antonia R. Sepulveda, Kasper Hoebe, Samuel S. Pan, Yong-Guang Yang, Suzanne Lentzsch, Markus Y. Mapara
Preexisting lung-restricted autoantibodies (LRAs) are associated with a higher incidence of primary graft dysfunction (PGD), although it remains unclear whether LRAs can drive its pathogenesis. In syngeneic murine left lung transplant recipients, preexisting LRAs worsened graft dysfunction, which was evident by impaired gas exchange, increased pulmonary edema, and activation of damage-associated pathways in lung epithelial cells. LRA-mediated injury was distinct from ischemia-reperfusion injury since deletion of donor nonclassical monocytes and host neutrophils could not prevent graft dysfunction in LRA-pretreated recipients. Whole LRA IgG molecules were necessary for lung injury, which was mediated by the classical and alternative complement pathways and reversed by complement inhibition. However, deletion of Fc receptors in donor macrophages or mannose-binding lectin in recipient mice failed to rescue lung function. LRA-mediated injury was localized to the transplanted lung and dependent on IL-1β–mediated permeabilization of pulmonary vascular endothelium, which allowed extravasation of antibodies. Genetic deletion or pharmacological inhibition of IL-1R in the donor lungs prevented LRA-induced graft injury. In humans, preexisting LRAs were an independent risk factor for severe PGD and could be treated with plasmapheresis and complement blockade. We conclude that preexisting LRAs can compound ischemia-reperfusion injury to worsen PGD for which complement inhibition may be effective.
Wenbin Yang, Emily Jeong Cerier, Félix L. Núñez-Santana, Qiang Wu, Yuanqing Yan, Chitaru Kurihara, Xianpeng Liu, Anjana Yeldandi, Nigar Khurram, Diego Avella-Patino, Haiying Sun, G.R. Scott Budinger, Daniel Kreisel, Thalachallour Mohanakumar, Emilia Lecuona, Ankit Bharat
Graft-versus-host disease (GVHD), manifesting in either acute (aGVHD) or chronic (cGVHD), presents significant life-threatening complications following allogeneic hematopoietic cell transplantation. Here, we investigated Friend Virus Leukemia Integration 1 (Fli-1) in GVHD pathogenesis and validated Fli-1 as a therapeutic target. Using genetic approaches, we found that Fli-1 dynamically regulates different T-cell subsets in allogeneic responses and pathogenicity in the development of aGVHD and cGVHD. Compared to homozygous Fli1-deficient or WT T cells, heterozygous Fli1-deficient T cells induced the mildest GVHD supported by lowest Th1 and Th17 differentiation. Single-cell RNA sequencing analysis revealed that Fli-1 differentially regulated CD4 versus CD8 T-cell response. Fli-1 promoted the transcription of Th1/Th17-pathways and TCR-inducible transcription factors in CD4 T cells, while suppressing activation and function-related gene pathways in CD8 T cells. Importantly, low-dose of camptothecin, topotecan or etoposide exhibited action as potent Fli-1 inhibitors and significantly attenuated GVHD severity while preserving the graft-versus-leukemia (GVL) effect. The observation was extended to a xenograft model where GVHD was induced by human T cells. In conclusion, we provide the evidence that Fli-1 plays a crucial role in alloreactive CD4+ T-cell activation and differentiation, and that targeting Fli-1 may be an attractive strategy for treating GVHD without compromising GVL effect.
Steven Schutt, Yongxia Wu, Arjun Kharel, David Bastian, Hee-Jin Choi, M. Hanief Sofi, Corey Mealer, Brianyell McDaniel Mims, Hung Nguyen, Chen Liu, Kris Helke, Weiguo Cui, Xian Zhang, Yaacov Ben-David, Xue-Zhong Yu
Primary graft dysfunction (PGD) is the leading cause of postoperative mortality in lung transplant recipients and the most important risk factor for development of chronic lung allograft dysfunction. The mechanistic basis for the variability in the incidence and severity of PGD between lung transplant recipients is not known. Using a murine orthotopic vascularized lung transplant model, we found that redundant activation of Toll-like receptors 2 and 4 (TLR2 and -4) on nonclassical monocytes activates MyD88, inducing the release of the neutrophil attractant chemokine CXCL2. Deletion of Itgam (encodes CD11b) in nonclassical monocytes enhanced their production of CXCL2 and worsened PGD, while a CD11b agonist, leukadherin-1, administered only to the donor lung prior to lung transplantation, abrogated CXCL2 production and PGD. The damage-associated molecular pattern molecule HMGB1 was increased in peripheral blood samples from patients undergoing lung transplantation after reperfusion and induced CXCL2 production in nonclassical monocytes via TLR4/MyD88. An inhibitor of HMGB1 administered to the donor and recipient prior to lung transplantation attenuated PGD. Our findings suggest that CD11b acts as a molecular brake to prevent neutrophil recruitment by nonclassical monocytes following lung transplantation, revealing an attractive therapeutic target in the donor lung to prevent PGD in lung transplant recipients.
Melissa Querrey, Stephen Chiu, Emilia Lecuona, Qiang Wu, Haiying Sun, Megan Anderson, Megan Kelly, Sowmya Ravi, Alexander V. Misharin, Daniel Kreisel, Ankit Bharat, G.R. Scott Budinger
Solid organ transplantation is the preferred treatment for end-stage organ failure. Although transplant recipients takelife-long immunosuppressive drugs, a substantial percentage of them still reject their allografts. Strikingly, barrier organs colonized with microbiota have significantly shorter half-lives than non-barrier transplanted organs, even in immunosuppressed hosts. We previously demonstrated that skin allografts mono-colonized with the common human commensal Staphylococcus epidermidis (S.epi) are rejected faster than germ-free (GF) allografts in mice because the presence of S.epi augments the effector alloimmune response locally in the graft. Here, we tested whether host immune responses against graft-resident commensal microbes, including S.epi, can damage colonized grafts independently from the alloresponse. Naïve hosts mounted an anti-commensalT cell response to colonized, but not GF, syngeneic skin grafts. Whereas naïve anti-graft-commensal T cells modestly damaged colonized syngeneic skin grafts, hosts with prior anti-commensal T cell memory mounted a post-transplant immune response against graft-resident commensals that significantly damaged colonized, syngeneic skin grafts. Importantly, allograft recipients harboring this host-versus-commensal immune response resisted immunosuppression. The dual effectsof host-versus-commensal and host-versus-allograft responses may partially explain why colonized organs have poorer outcomes than sterile organs in the clinic.
Isabella D. Pirozzolo, Martin Sepulveda, Luqiu Chen, Ying Wang, Yuk Man Lei, Zhipeng Li, Rena Li, Husain Sattar, Betty R. Theriault, Yasmine Belkaid, Anita S. Chong, Maria-Luisa Alegre
Lymph node (LN) fibroblastic reticular cells (FRCs) define LN niches and regulate lymphocyte homeostasis through producing diverse extracellular matrix (ECM) components. We examined the role of ECM laminin α4 (Lama4) using FRC-Lama4 conditional KO Pdgfrb-Cre–/– × Lama4fl/fl mice. Single-cell RNA-sequencing (scRNA-Seq) data showed the promoter gene Pdgfrb was exclusively expressed in FRCs. Depleting FRC-Lama4 reduced Tregs and dendritic cells, decreased high endothelial venules, impaired the conduit system, and downregulated T cell survival factors in LNs. FRC-Lama4 depletion impaired the homing of lymphocytes to LNs in homeostasis and after allografting. Alloantigen-specific T cells proliferated, were activated to greater degrees in LNs lacking FRC-Lama4, and were more prone to differentiate into effector phenotypes relative to the Treg phenotype. In murine cardiac transplantation, tolerogenic immunosuppression was not effective in FRC-Lama4 recipients, which produced more alloantibodies than WT. After lung transplantation, FRC-Lama4–KO mice had more severe graft rejection with fewer Tregs in their LNs. Overall, FRC-Lama4 critically contributes to a tolerogenic LN niche by supporting T cell migration, constraining T cell activation and proliferation, and promoting Treg differentiation. Hence, it serves as a therapeutic target for immunoengineering.
Lushen Li, Marina W. Shirkey, Tianshu Zhang, Wenji Piao, Xiaofei Li, Jing Zhao, Zhongcheng Mei, Yizhan Guo, Vikas Saxena, Allison Kensiski, Samuel J. Gavzy, Yang Song, Bing Ma, Jing Wu, Yanbao Xiong, Long Wu, Xiaoxuan Fan, Holly Roussey, Meng Li, Alexæander S. Krupnick, Reza Abdi, Jonathan S. Bromberg
DNA methyltransferase 3a (DNMT3a) is an important part of the epigenetic machinery that stabilizes patterns of activated T-cell responses. We hypothesized that donor T-cell DNMT3a regulates alloreactivity after allogeneic blood and marrow transplantation (allo-BMT). T-cell conditional Dnmt3a knock-out (KO) animals were used as donors in murine allo-BMT models. Mice receiving allo-BMT from KO donors developed severe acute graft-versus-host disease (aGVHD), with increases in inflammatory cytokine levels and organ histopathology. KO T-cells migrated and proliferated in secondary lymphoid organs earlier and demonstrated a trafficking advantage to the small intestine. Donor T-cell subsets were purified post-BMT for whole genome bisulfite sequencing (WGBS) and RNA sequencing. KO T-cells had similar global methylation to wild-type (WT), with distinct, localized areas of hypomethylation. Using a highly sensitive computational method, we produced a comprehensive profile of the altered epigenome landscape. Hypomethylation corresponded with changes in gene expression in several pathways of T-cell signaling and differentiation. Additionally, Dnmt3a KO T-cells conveyed superior graft-versus-tumor activity. Our findings demonstrate a critical role for DNMT3a in regulating T-cell alloreactivity and illuminate pathways that control T-cell tolerance. These results also provide a platform to decipher clinical data that associate donor DNMT3a mutations with increased GVHD, decreased relapse, and improved survival.
Yiouli P. Ktena, Michael A. Koldobskiy, Michael I. Barbato, Han-Hsuan Fu, Leo Luznik, Nicolas J. Llosa, Azeb Haile, Orly R. Klein, Chen Liu, Christopher J. Gamper, Kenneth R. Cooke
Antigen-presenting cells (APC) integrate signals emanating from local pathology and program appropriate T cell responses. In allogeneic hematopoietic stem cell transplantation (alloHCT), recipient conditioning releases Damage-Associated Molecular Patterns (DAMPs) that generate pro-inflammatory APC that secrete IL-12, which is a driver of donor Type 1 T helper (Th1) responses causing graft vs. host disease (GVHD). Nevertheless, other mechanisms exist to initiate alloreactive T cells responses, as recipients with disrupted DAMP signaling or lacking IL-12 develop GVHD. We established that tissue damage signals are perceived directly by donor CD4+ T cells and promoted T cell expansion and differentiation. Specifically, the fibroblastic reticular cell-derived DAMP, IL-33, is increased by recipient conditioning and is critical for the initial activation, proliferation, and differentiation of alloreactive Th1 cells. IL-33-stimulation of CD4+ T cell was not required for lymphopenia-induced expansion, however. IL-33 promoted IL-12-independent expression of Tbet and generation of Th1 cells that infiltrated GVHD target tissues. Mechanistically, IL-33 augmented CD4+ T cell TCR-associated signaling pathways in response to alloantigen. This enhanced T cell expansion and Th1 polarization, but inhibited the expression of regulatory molecules like IL-10 and Foxp3. These data established an unappreciated role for IL-33 as a costimulatory signal for donor Th1 generation after alloHCT.
Gaelen K. Dwyer, Lisa R. Mathews, Jose A. Villegas, Anna Lucas, Anne Gonzalez de Peredo, Bruce R. Blazar, Jean-Philippe Girard, Amanda C. Poholek, Sanjiv A. Luther, Warren Shlomchik, Hēth R. Turnquist
Once human photoreceptors die, they do not regenerate, thus photoreceptor transplantation has emerged as a potential treatment approach for blinding diseases. Improvements in transplant organization, donor cell maturation and synaptic connectivity to the host will be critical in advancing this technology to clinical practice. Unlike the unstructured grafts of prior cell suspension transplantations into end-stage degeneration models, we describe extensive incorporation of iPSC retinal organoid-derived human photoreceptors into mice with cone dysfunction. This incorporative phenotype was validated in both cone-only as well as pan-photoreceptor transplantations. Rather than forming a glial barrier, Müller cells extended throughout the graft, even forming a series of adherens junctions between mouse and human cells, reminiscent of an outer limiting membrane. Donor-host interaction appeared to promote polarisation as well as development of morphological features critical for light detection, namely formation of inner and well stacked outer segments oriented towards the retinal pigment epithelium. Putative synapse formation and graft function was evident both at a structural and electrophysiological level. Overall, these results show that human photoreceptors interact readily with a partially degenerated retina. Moreover, incorporation into the host retina appears to be beneficial to graft maturation, polarisation and function.
Sylvia J. Gasparini, Karen Tessmer, Miriam Reh, Stephanie Wieneke, Madalena Carido, Manuela Völkner, Oliver Borsch, Anka Swiersy, Marta Zuzic, Olivier Goureau, Thomas Kurth, Volker Busskamp, Günther Zeck, Mike O. Karl, Marius Ader
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