Tissue-infiltrating alloreactive T cells require Id3 to deflect PD-1-mediated immune suppression during GVHD.

ABSTRACT: Persisting alloreactive donor T cells in target tissues are a determinant of graft-versus-host disease (GVHD), but the transcriptional regulators that control the persistence and function of tissue-infiltrating T cells remain elusive. We demonstrate here that Id3, a DNA-binding inhibitor, is critical for sustaining T-cell responses in GVHD target tissues in mice, including the liver and intestine. Id3 loss results in aberrantly expressed PD-1 in polyfunctional T helper 1 (Th1) cells, decreased tissue-infiltrating PD-1+ polyfunctional Th1 cell numbers, impaired maintenance of liver TCF-1+ progenitor-like T cells, and inhibition of GVHD. PD-1 blockade restores the capacity of Id3-ablated donor T cells to mediate GVHD. Single-cell RNA-sequencing analysis revealed that Id3 loss leads to significantly decreased CD28- and PI3K/AKT-signaling activity in tissue-infiltrating polyfunctional Th1 cells, an indicator of active PD-1/PD-L1 effects. Id3 is also required for protecting CD8+ T cells from the PD-1 pathway-mediated suppression during GVHD. Genome-wide RNA-sequencing analysis reveals that Id3 represses transcription factors (e.g., Nfatc2, Fos, Jun, Ets1, and Prdm1) that are critical for PD-1 transcription, exuberant effector differentiation, and interferon responses and dysfunction of activated T cells. Id3 achieves these effects by restraining the chromatin accessibility for these transcription factors. Id3 ablation in donor T cells preserved their graft vs tumor effects in mice undergoing allogeneic hematopoietic stem cell transplantation. Furthermore, CRISPR/Cas9 knockout of ID3 in human CD19-directed chimeric antigen receptor T cells retained their antitumor activity in NOD/SCID/IL2Rg-/- mice early after administration. These findings identify that ID3 is an important target to reduce GVHD, and the gene-editing program of ID3 may have broad implications in T-cell-based immunotherapy.

Mechanism of a COVID-19 nanoparticle vaccine candidate that elicits a broadly neutralizing antibody response to SARS-CoV-2 variants.

Vaccines that induce potent neutralizing antibody (NAb) responses against emerging variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are essential for combating the coronavirus disease 2019 (COVID-19) pandemic. We demonstrated that mouse plasma induced by self-assembling protein nanoparticles (SApNPs) that present 20 rationally designed S2GΔHR2 spikes of the ancestral Wuhan-Hu-1 strain can neutralize the B.1.1.7, B.1.351, P.1, and B.1.617 variants with comparable potency. The adjuvant effect on vaccine-induced immunity was investigated by testing 16 formulations for the multilayered I3-01v9 SApNP. Using single-cell sorting, monoclonal antibodies (mAbs) with diverse neutralization breadth and potency were isolated from mice immunized with the receptor binding domain (RBD), S2GΔHR2 spike, and SApNP vaccines. The mechanism of vaccine-induced immunity was examined in the mouse model. Compared with the soluble spike, the I3-01v9 SApNP showed sixfold longer retention, fourfold greater presentation on follicular dendritic cell dendrites, and fivefold stronger germinal center reactions in lymph node follicles.

Mechanism of a COVID-19 nanoparticle vaccine candidate that elicits a broadly neutralizing antibody response to SARS-CoV-2 variants.

Vaccines that induce potent neutralizing antibody (NAb) responses against emerging variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are essential for combating the coronavirus disease 2019 (COVID-19) pandemic. We demonstrated that mouse plasma induced by self-assembling protein nanoparticles (SApNPs) that present 20 rationally designed S2GΔHR2 spikes of the ancestral Wuhan-Hu-1 strain can neutralize the B.1.1.7, B.1.351, P.1, and B.1.617 variants with the same potency. The adjuvant effect on vaccine-induced immunity was investigated by testing 16 formulations for the multilayered I3-01v9 SApNP. Using single-cell sorting, monoclonal antibodies (mAbs) with diverse neutralization breadth and potency were isolated from mice immunized with the receptor binding domain (RBD), S2GΔHR2 spike, and SApNP vaccines. The mechanism of vaccine-induced immunity was examined in mice. Compared with the soluble spike, the I3-01v9 SApNP showed 6-fold longer retention, 4-fold greater presentation on follicular dendritic cell dendrites, and 5-fold stronger germinal center reactions in lymph node follicles.

Single-component, self-assembling, protein nanoparticles presenting the receptor binding domain and stabilized spike as SARS-CoV-2 vaccine candidates.

Vaccination against SARS-CoV-2 provides an effective tool to combat the COVID-19 pandemic. Here, we combined antigen optimization and nanoparticle display to develop vaccine candidates for SARS-CoV-2. We first displayed the receptor-binding domain (RBD) on three self-assembling protein nanoparticle (SApNP) platforms using the SpyTag/SpyCatcher system. We then identified heptad repeat 2 (HR2) in S2 as the cause of spike metastability, designed an HR2-deleted glycine-capped spike (S2GΔHR2), and displayed S2GΔHR2 on SApNPs. An antibody column specific for the RBD enabled tag-free vaccine purification. In mice, the 24-meric RBD-ferritin SApNP elicited a more potent neutralizing antibody (NAb) response than the RBD alone and the spike with two stabilizing proline mutations in S2 (S2P). S2GΔHR2 elicited twofold higher NAb titers than S2P, while S2GΔHR2 SApNPs derived from multilayered E2p and I3-01v9 60-mers elicited up to 10-fold higher NAb titers. The S2GΔHR2-presenting I3-01v9 SApNP also induced critically needed T cell immunity, thereby providing a promising vaccine candidate.

Graft-versus-host disease depletes plasmacytoid dendritic cell progenitors to impair tolerance induction.

Graft-versus-host disease (GVHD) causes failed reconstitution of donor plasmacytoid dendritic cells (pDCs) that are critical for immune protection and tolerance. We used both murine and human systems to uncover the mechanisms whereby GVHD induces donor pDC defects. GVHD depleted Flt3-expressing donor multipotent progenitors (MPPs) that sustained pDCs, leading to impaired generation of pDCs. MPP loss was associated with decreased amounts of MPP-producing hematopoietic stem cells (HSCs) and oxidative stress-induced death of proliferating MPPs. Additionally, alloreactive T cells produced GM-CSF to inhibit MPP expression of Tcf4, the transcription factor essential for pDC development, subverting MPP production of pDCs. GM-CSF did not affect the maturation of pDC precursors. Notably, enhanced recovery of donor pDCs upon adoptive transfer early after allogeneic HSC transplantation repressed GVHD and restored the de novo generation of donor pDCs in recipient mice. pDCs suppressed the proliferation and expansion of activated autologous T cells via a type I IFN signaling-dependent mechanism. They also produced PD-L1 and LILRB4 to inhibit T cell production of IFN-γ. We thus demonstrate that GVHD impairs the reconstitution of tolerogenic donor pDCs by depleting DC progenitors rather than by preventing pDC maturation. MPPs are an important target to effectively bolster pDC reconstitution for controlling GVHD.

Single-component, self-assembling, protein nanoparticles presenting the receptor binding domain and stabilized spike as SARS-CoV-2 vaccine candidates.

Vaccination against SARS-CoV-2 provides an effective tool to combat the COIVD-19 pandemic. Here, we combined antigen optimization and nanoparticle display to develop vaccine candidates for SARS-CoV-2. We first displayed the receptor-binding domain (RBD) on three self-assembling protein nanoparticle (SApNP) platforms using the SpyTag/SpyCatcher system. We then identified heptad repeat 2 (HR2) in S2 as the cause of spike metastability, designed an HR2-deleted glycine-capped spike (S2GΔHR2), and displayed S2GΔHR2 on SApNPs. An antibody column specific for the RBD enabled tag-free vaccine purification. In mice, the 24-meric RBD-ferritin SApNP elicited a more potent neutralizing antibody (NAb) response than the RBD alone and the spike with two stabilizing proline mutations in S2 (S2P). S2GΔHR2 elicited two-fold-higher NAb titers than S2P, while S2GΔHR2 SApNPs derived from multilayered E2p and I3-01v9 60-mers elicited up to 10-fold higher NAb titers. The S2GΔHR2-presenting I3-01v9 SApNP also induced critically needed T-cell immunity, thereby providing a promising vaccine candidate.

New insights into the basic biology of acute graft-versus-host-disease.

Although allogeneic hematopoietic stem cell transplantation is an important therapy for many hematological and non-hematological diseases, acute graft-versus-host-disease (aGVHD) is a major obstacle to its success. The pathogenesis of aGVHD is divided into three distinct phases which occur largely as the result of interactions between infused donor T cells and numerous cell types of both hematopoietic and non-hematopoietic origin. In light of the disease's immensely complex biology, epigenetics has emerged as a framework with which to examine aGVHD. This review focuses on new findings that clarify the roles specific epigenetic regulators play in T cell-mediated aGVHD development and discusses how their modulation could disrupt that process to beneficial effects. DNA methyltransferases, histone methyltransferases and histone deacetylases are the most closely studied regulators across aGVHD priming, induction and effector phases and have been manipulated using drugs and other methods in both murine models and clinical trials to varying degrees of success. Antigen-presenting cells, effector T cells and memory T cells, among others, are targeted and affected by these regulators in different ways. Finally, our review highlights new directions for study and potential novel targets for modulation to abrogate aGVHD.