skip to Main Content
Selected Publications

Regulatory CD8 T cells that recognize Qa-1 expressed by CD4 T-helper cells inhibit rejection of heart allografts

Proc Natl Acad Sci U S A. 2020 Mar 17;117(11):6042-6046. doi: 10.1073/pnas.1918950117.

Induction of longstanding immunologic tolerance is essential for the survival of transplanted organs and tissues. Despite recent advances in immunosuppression protocols, allograft damage inflicted by antibody specific for donor organs continues to represent a major obstacle to graft survival. Here we report that activation of regulatory CD8 T cells (CD8 Treg) that recognize the Qa-1 class Ib major histocompatibility complex (MHC), a mouse homolog of human leukocyte antigen-E (HLA-E), inhibits antibody-mediated immune rejection of heart allografts. We analyzed this response using a mouse model that harbors a point mutation in the class Ib MHC molecule Qa-1, which disrupts Qa-1 binding to the T cell receptor (TCR)-CD8 complex and impairs the CD8 Treg response. Despite administration of cytotoxic T lymphocyte antigen 4 (CTLA-4) immunoglobulin (Ig), Qa-1 mutant mice developed robust donor-specific antibody responses and accelerated heart graft rejection. We show that these allo-antibody responses reflect diminished Qa-1-restricted CD8 Treg-mediated suppression of host follicular helper T cell-dependent antibody production. These findings underscore the critical contribution of this Qa-1/HLA-E-dependent regulatory pathway to maintenance of transplanted organs and suggest therapeutic approaches to ameliorate allograft rejection.

Blocking IFNAR1 inhibits multiple myeloma-driven Treg expansion and immunosuppression

J Clin Invest. 2018 Jun 1;128(6):2487-2499. doi: 10.1172/JCI88169.

Despite significant advances in the treatment of multiple myeloma (MM), most patients succumb to disease progression. One of the major immunosuppressive mechanisms that is believed to play a role in myeloma progression is the expansion of regulatory T cells (Tregs). In this study, we demonstrate that myeloma cells drive Treg expansion and activation by secreting type 1 interferon (IFN). Blocking IFN α and β receptor 1 (IFNAR1) on Tregs significantly decreases both myeloma-associated Treg immunosuppressive function and myeloma progression. Using syngeneic transplantable murine myeloma models and bone marrow (BM) aspirates of MM patients, we found that Tregs were expanded and activated in the BM microenvironment at early stages of myeloma development. Selective depletion of Tregs led to a complete remission and prolonged survival in mice injected with myeloma cells. Further analysis of the interaction between myeloma cells and Tregs using gene sequencing and enrichment analysis uncovered a feedback loop, wherein myeloma-cell-secreted type 1 IFN induced proliferation and expansion of Tregs. By using IFNAR1-blocking antibody treatment and IFNAR1-knockout Tregs, we demonstrated a significant decrease in myeloma-associated Treg proliferation, which was associated with longer survival of myeloma-injected mice. Our results thus suggest that blocking type 1 IFN signaling represents a potential strategy to target immunosuppressive Treg function in MM.

Human regulatory T cells undergo self-inflicted damage via granzyme pathways upon activation

JCI Insight. 2017 Nov 2;2(21). pii: 91599. doi: 10.1172/jci.insight.91599.

Tregs hold great promise as a cellular therapy for multiple immunologically mediated diseases, given their ability to control immune responses. The success of such strategies depends on the expansion of healthy, suppressive Tregs ex vivo and in vivo following the transfer. In clinical studies, levels of transferred Tregs decline sharply in the blood within a few days of the transfer. Tregs have a high rate of apoptosis. Here, we describe a new mechanism of Treg self-inflicted damage. We show that granzymes A and -B (GrA and GrB), which are highly upregulated in human Tregs upon stimulation, leak out of cytotoxic granules to induce cleavage of cytoplasmic and nuclear substrates, precipitating apoptosis in target cells. GrA and GrB substrates were protected from cleavage by inhibiting granzyme activity in vitro. Additionally, we show – by using cytometry by time of flight (CYTOF) – an increase in GrB-expressing Tregs in the peripheral blood and renal allografts of transplant recipients undergoing rejection. These GrB-expressing Tregs showed an activated phenotype but were significantly more apoptotic than non-GrB expressing Tregs. This potentially novel finding improves our understanding of Treg survival and suggests that manipulating Gr expression or activity might be useful for designing more effective Treg therapies.

Integrated Kidney Exosome Analysis for the Detection of Kidney Transplant Rejection

ACS Nano. 2017 Nov 28;11(11):11041-11046. doi: 10.1021/acsnano.7b05083. Epub 2017 Oct 25.

Kidney transplant patients require life-long surveillance to detect allograft rejection. Repeated biopsy, albeit the clinical gold standard, is an invasive procedure with the risk of complications and comparatively high cost. Conversely, serum creatinine or urinary proteins are noninvasive alternatives but are late markers with low specificity. We report a urine-based platform to detect kidney transplant rejection. Termed iKEA (integrated kidney exosome analysis), the approach detects extracellular vesicles (EVs) released by immune cells into urine; we reasoned that T cells, attacking kidney allografts, would shed EVs, which in turn can be used as a surrogate marker for inflammation. We optimized iKEA to detect T-cell-derived EVs and implemented a portable sensing system. When applied to clinical urine samples, iKEA revealed high level of CD3-positive EVs in kidney rejection patients and achieved high detection accuracy (91.1%). Fast, noninvasive, and cost-effective, iKEA could offer new opportunities in managing transplant recipients, perhaps even in a home setting.

Targeted Delivery of Immunomodulators to Lymph Nodes

Cell Rep. 2016 May 10;15(6):1202-13. doi: 10.1016/j.celrep.2016.04.007. Epub 2016 Apr 28.

Active-targeted delivery to lymph nodes represents a major advance toward more effective treatment of immune-mediated disease. The MECA79 antibody recognizes peripheral node addressin molecules expressed by high endothelial venules of lymph nodes. By mimicking lymphocyte trafficking to the lymph nodes, we have engineered MECA79-coated microparticles containing an immunosuppressive medication, tacrolimus. Following intravenous administration, MECA79-bearing particles showed marked accumulation in the draining lymph nodes of transplanted animals. Using an allograft heart transplant model, we show that targeted lymph node delivery of microparticles containing tacrolimus can prolong heart allograft survival with negligible changes in tacrolimus serum level. Using MECA79 conjugation, we have demonstrated targeted delivery of tacrolimus to the lymph nodes following systemic administration, with the capacity for immune modulation in vivo.

Structure of human immunoproteasome with a reversible and noncompetitive inhibitor

Nat Commun. 2017 Nov 22;8(1):1692. doi: 10.1038/s41467-017-01760-5.

Proteasome inhibitors benefit patients with multiple myeloma and B cell-dependent autoimmune disorders but exert toxicity from inhibition of proteasomes in other cells. Toxicity should be minimized by reversible inhibition of the immunoproteasome β5i subunit while sparing the constitutive β5c subunit. Here we report β5i-selective inhibition by asparagine-ethylenediamine (AsnEDA)-based compounds and present the high-resolution cryo-EM structural analysis of the human immunoproteasome. Despite inhibiting noncompetitively, an AsnEDA inhibitor binds the active site. Hydrophobic interactions are accompanied by hydrogen bonding with β5i and β6 subunits. The inhibitors are far more cytotoxic for myeloma and lymphoma cell lines than for hepatocarcinoma or non-activated lymphocytes. They block human B-cell proliferation and promote apoptotic cell death selectively in antibody-secreting B cells, and to a lesser extent in activated human T cells. Reversible, β5i-selective inhibitors may be useful for treatment of diseases involving activated or neoplastic B cells or activated T cells.

Recent Publications
  • Ordikhani F, Uehara M, Kasinath V, Dai L, Eskandari SK, Bahmani B, Yonar M, Azzi JR, Haik Y, Sage PT, Murphy GF, Annabi N, Schatton T, Guleria I, Abdi R. Targeting antigen-presenting cells by anti-PD-1 nanoparticles augments antitumor immunity. JCI Insight. 2018 Oct 18;3(20). PubMed PMID: 30333312.
  • Bahmani B, Uehara M, Jiang L, Ordikhani F, Banouni N, Ichimura T, Solhjou Z, Furtmüller GJ, Brandacher G, Alvarez D, von Andrian UH, Uchimura K, Xu Q, Vohra I, Yilmam OA, Haik Y, Azzi JR, Kasinath V, Bromberg JS, McGrath MM, Abdi R. Targeted delivery of immune therapeutics to lymph nodes prolongs cardiac allograft survival. J Clin Invest. 2018 Oct 2. PubMed PMID: 30277476.
  • Borges TJ, Murakami N, Machado FD, Murshid A, Lang BJ, Lopes RL, Bellan LM, Uehara M, Antunes KH, Pérez-Saéz MJ, Birrane G, Vianna P, Gonçalves JIB, Zanin RF, Azzi JR, Abdi R, Ishido S, Shin JS, Souza APD, Calderwood SK, Riella LV, Bonorino C. March1-dependent modulation of donor MHC II on CD103(+) dendritic cells mitigates alloimmunity. Nat Commun. 2018 Aug 28;9(1):3482. PubMed PMID: 30154416; PMC6113260.
  • Kurdi AT, Glavey SV, Bezman NA, Jhatakia A, Guerriero JL, Manier S, Moschetta M, Mishima Y, Roccaro A, Detappe A, Liu CJ, Sacco A, Huynh D, Tai YT, Robbins MD, Azzi JR, Ghobrial IM. Antibody-Dependent Cellular Phagocytosis by Macrophages is a Novel Mechanism of Action of Elotuzumab. Mol Cancer Ther. 2018 Jul;17(7):1454-63. PubMedPMID: 29654064; PMC6030488.
  • Kawano Y, Zavidij O, Park J, Moschetta M, Kokubun K, Mouhieddine TH, Manier S, Mishima Y, Murakami N, Bustoros M, Pistofidis RS, Reidy M, Shen YJ, Rahmat M, Lukyanchykov P, Karreci ES, Tsukamoto S, Shi J, Takagi S, Huynh D, Sacco A, Tai YT, Chesi M, Bergsagel PL, Roccaro AM, Azzi JR, Ghobrial IM. Blocking IFNAR1 inhibits multiple myeloma-driven Treg expansion and immunosuppression. J Clin Invest. 2018 Jun 1;128(6):2487-99. PubMed PMID: 29558366; PMC5983341.
Back To Top