Member, Molecular Oncology Program
GRU Cancer Center
Associate Professor of Radiology
1120 15th Street, CN 3154
Phone: (706) 721-8736
As a physician in Russia and later Hungary, Dr. Anatolij Horuzsko saw how kidney transplants gave patients’ their lives back. Yet the risk of organ rejection remained. The problem of rejection drew him to molecular biology and research. His current studies focus on organ transplantation and the role of a key molecule, Human Leukocyte Antigen-G (HLA-G). Dr. Horuzsko is using laboratory tests and animal models to determine whether HLA-G can be coaxed into creating tolerance for transplanted organs.
Dr. Horuzsko was awarded an MD and was board-certified by the Pediatric Medical School in St. Petersburg, Russia, in 1976; he pursued studies in immunology and was board-certified in immunology and allergy in 1979 by the Pediatric Medical School. He then received a PhD in immunology from the Institute of Experimental Medicine, Russian Academy of Sciences in St. Petersburg, Russia, in 1980. He also earned an MD from “Semmelweis” University of Medicine, Budapest, Hungary, in 1986, and a second PhD, also in immunology from the Hungarian Academy of Sciences, Hungary, in 1987. He received his Hungarian Medical License, Budapest, Hungary, in 1988.
Dr. Horuzsko has contributed to 39 articles in peer-reviewed professional journals. He has authored or contributed to seven book chapters. He and Dr. J. Kaminski have applied for two patents related to HLA-G. Dr. Horuzsko has been listed with Who’s Who in America since 2004 and with Who’s Who in the World since 2005.
Organ transplantation has demonstrated both survival and quality of life benefits for selected patients with end-stage disease. The development of immunosuppressive therapies has led to remarkable success of clinical allotransplantation. Despite improvements in early survival, however, survival beyond 5 years remains poor as a result of chronic graft rejection.
Novel therapeutic strategies, such as modulation of dendritic cell and T cell functions, have shown great potential in clinical transplantation. HLA-G is a molecule that plays a significant role in establishing complex mechanisms to protect semi-allogeneic fetuses from rejection by the maternal immune system. The tolerogenic potential of HLA-G is mediated by its exclusive binding to the inhibitory receptors on immunocompetent cells that modulate cell functions. However, the mechanisms by which HLA-G modulates the function of dendritic cells and T cells are thus far incompletely understood. The unique characteristics of both cell surface and soluble isoforms of HLA-G, the formation of disulfide-bonded dimers with the potential to augment inhibitory receptor signaling and the function of HLA-G as a preferential ligand for the immunoglobulin-like transcript receptors make HLA-G very important in fundamental approaches for modulation of immune responses to improve allogeneic graft survival in clinical transplantation.
Bettering our understanding of HLA-G in the transplantation field will also improve our understanding of HLA-G in relation to cancer.
HLA-G-based immunotherapy against allograft rejection.
Our long-term goals aim to determine the mechanisms of modulation of dendritic cells, myeloid-derived suppressor cells and T cells by HLA-G, and to design a highly potent HLA-G-based immunotherapy against allograft rejection. We have developed models to determine the mechanisms of tolerogenic function of HLA-G in vitro and in vivo. Our central hypothesis, based on our published and strong preliminary data from experiments involving HLA-G-mediated human tolerogenic dendritic cells in vitro and receptor transgenic mice in vivo, is that different isoforms of HLA-G have various immunomodulatory effects through the inhibitory receptors and that knowledge of this can be crucial in designing the most potent form of HLA-G. This hypothesis is reflected in the study of the mechanism of tolerization of dendritic cells and mechanisms of prolongation of allograft survival mediated by HLA-G and inhibitory receptors on myeloid-derived suppressor cells. Data obtained from these studies will reveal the potential of HLA-G in modulation of immune responses and will aid in development of novel strategies for translation into the clinic to improve allograft survival in patients and treat graft-versus-host disease, allergy and autoimmune diseases.
Role of HLA-G isoforms and inhibitory receptors in solid organ transplantation.
A key factor driving chronic rejection in clinical transplantation is a persistent T cell-mediated alloimmune response. Therefore, the development of novel therapeutic strategies to target T cell alloimmune responses would be important in preventing and managing chronic rejection. Allogeneic stimulation drives the expression of several activating and inhibitory receptors on T cells and dendritic cells (DCs) and offers the possibility of modulating immune responses.
One strong inhibitory receptor on human T cells and DCs is immunoglobulin-like transcript 2, ILT2 (also known as LILRB1, LIR1, CD85j). We have demonstrated that transgenic mice expressing ILT2 exhibit long-term prolongation of allograft survival or acceptance of an allogeneic skin transplant as a result of the interaction between ILT2 and its ligand. Another inhibitory receptor, preferentially expressed on DCs, is ILT4 (LILRB2, LIR2, CD85d). Our data demonstrated that transgenic mice expressing ILT4 exclusively on DCs have prolonged allograft survival mediated by the ligand and ILT4-modified DCs. The natural ligand for ILT2 and ILT4 receptors is HLA-G. HLA-G is characterized by tissue-restricted expression, limited polymorphisms and seven isoforms (HLA-G1 to HLA-G7, of which HLA-G5, HLA-G6 and HLA-G7 are soluble isoforms).
Immunomodulatory effects of HLA-G and their inhibitory receptors in EAE.
Inflammation and autoimmunity are central components of multiple sclerosis (MS), a demyelinating disease of the central nervous system (CNS). The development of antigen-specific T cell responses and the infiltration of activated lymphocytes into the CNS parenchyma result in inflammation-mediated myelin injury in MS. Inflammatory responses are regulated through multiple pathways that often involve dendritic cells (DC) and T cells, and much effort has been devoted to understanding the key pathways that regulate these cells. Immunoglobulin-like transcript receptors (ILTs, CD85, LILRB) are a family of human inhibitory and activating receptors, specifically expressed on DC and T cells, which modify the immune cells’ functions.
ILTs appear to be involved in the induction of tolerance. The association of homozygous ILT6 deficiency with MS in the German population is the first disease association of a polymorphism of the ILT family. The precise role of ILTs in preventing autoimmune diseases, including MS, should be determined.
Ligands for ILTs are HLA molecules, and the preferential ligand is HLA-G. HLA-G is characterized by tissue-restricted expression, limited polymorphisms and seven isoforms (HLA-G1 to HLA-G7, of which HLA-G5, HLA-G6, and HLA-G7 are soluble rather than membrane-bound). Evidence suggests that HLA-G protects the fetus from attack by natural killer cells, macrophages, dendritic cells (DCs), monocytes and T cells by interacting with inhibitory receptors, such as immunoglobulin-like transcript 2 (ILT2) and ILT4, and by modifying cell functions. The most important functional isoforms of HLA-G include β2-microglobulin-associated HLA-G1 and HLA-G5. However, the immunological effect of these isoforms is different and independent from the form of ligand (whether monomer or dimer) and the affinity of the ligand-receptor interaction. Thus, the disulfide-linked dimer form of HLA-G is of special interest. There is accumulating evidence demonstrating that HLA-G is induced in the course of inflammatory pathologies, such as myositic lesions, psoriatic lesions, atopic dermatitis or in MS lesions. Therefore, HLA-G has been proposed as a mechanism to protect target tissues from autoaggressive inflammation and to serve as a fundamental mechanism of immune surveillance.
There is accumulating evidence to indicate a significant role of HLA-G in CNS immunity. HLA-G represents an inducible molecule that may be important for maintaining an anti-inflammatory milieu in the CNS. HLA-G-expressing cells and their inhibitory receptors provide significant immune inhibitory effects, and they represent a self-derived anti-inflammatory principle, possibly applicable as a strategy against the aggressive inflammatory responses that occur in the CNS of patients with autoimmune inflammatory CNS disorders, such as MS. Several studies indicate the role of HLA-G in controlling inflammation. It has been hypothesized that up-regulation of the immune-inhibitory HLA-G at sites of inflammation contributes to the limitation of organ/tissue damage and plays a key role in the mechanisms of tissue integrity.
The unique characteristics of both cell-surface and soluble isoforms of HLA-G, the formation of disulfide-bonded dimers with the potential to augment inhibitory-receptor signaling and the function of HLA-G as a preferential ligand for the ILTs make HLA-G very important in modulating immune responses against autoaggressive inflammation besides serving as a fundamental mechanism of immune surveillance.
We have developed in vitro and in vivo models to determine the role of HLA-G and its inhibitory receptors to control activation and function of DC and T cells. We are using three lines of ILT transgenic mice (ILT2, ILT2+/[beta]2m-/- and ILT4) and several isoforms of HLA-G (HLA-G1 membrane bound form, soluble HLA-G5 monomer and soluble HLA-G5 dimer forms) generated in our laboratory.
Our long-term goal is to identify the potential and possible mechanisms of modulation of autoimmune responsiveness by the HLA-G family and their inhibitory receptors, to determine their anti-inflammatory properties and to use this knowledge to design the best strategies to improve therapeutic outcomes in inflammatory disorders of the CNS and other autoimmune diseases.
Wu J, Zhang W, Liang S, Horuzsko A. Impaired adaptive immune responses in triggering receptor expressed on myeloid cells (TREM-1)-deficient mice. Manuscript in preparation.
Zhang W, Liang S, Wu J, Horuzsko A. Triggering receptor expressed on myeloid cells (TREM-1) is essential for the activation and recruitment of myeloid-derived suppressor cells. Manuscript in preparation.
Liang S, Zhang W, Wu J, Hernandez-Lopez P, Mulloy LL, Horuzsko A. Isoforms of HLA-G and their inhibitory receptors in human kidney allograft acceptance. Manuscript in preparation.
Wu J, Horuzsko A. Expression and functions of ILT receptors on tolerogenic dendritic cells. 2009, Human Immunology, accepted for publication.
Zhang M, Ou R, Horuzsko A, Moskophidis D. Constitutive expression of human ILT2 receptor on T cells is a critical negative regulator of virus-specific CD8+ T-cell response in mice with LCMV persistent infection. 2008, Journal of Virology, under consideration for publication.
Zhang W, Liang S, Wu J, Horuzsko A. Human inhibitory receptor ILT2 amplifies CD11b+Gr1+ myeloid derived suppressor cells that promote long-term survival of allografts. Transplantation. 2008 Oct;86(8):1125-34.
Liang S, Ristich V, Arase H, Dausset J, Carosella ED, Horuzsko A. Modulation of dendritic cell differentiation by HLA-G and ILT4 requires the IL-6—STAT3 signaling pathway. Proceedings of the National Academy of Sciences USA. 2008;105:8357-62.
Smith M, Bittner JG, White S, Smith D, Horuzsko A. HLA-G treated tolerogenic dendritic cells induce tolerogenic potential by increasing expression of B7-1(CD80) molecules. Transplantation Proceedings. 2008;40:1598-603.
Carosella ED, Horuzsko A. HLA-G and cancer. Seminars in Cancer Biology, 2007;17:411-12.
Ristich V, Zhang W. Liang S, Horuzsko A. Mechanisms of prolongation of allograft survival by HLA-GILT4-modified dendritic cells. Human Immunology. 2007; 68:264-71.
Liang S, Zhang W and Horuzsko A. Human ILT2 receptor associates with murine MHC class I molecules in vivo and impairs T cell function. European Journal of Immunology. 2006;36:2457-71.
Ristich V, Liang S, Zhang W, Wu J, Horuzsko A. Tolerization of dendritic cells by HLA-G. European Journal of Immunology. 2005;35:1133-42.
Liang S and Horuzsko A. Mobilizing dendritic cells for tolerance by engagement of immune inhibitory receptors for HLA-G. Human Immunology. 2003;64:1025-32.
Lenfant F, Pizzato N, Liang S, Davrinche C, Le Bouteiller P and Horuzsko A. Induction of HLA-G–restricted human cytomegalovirus pp65 (UL83)-specific cytotoxic T lymphocytes in HLA-G transgenic mice. Journal of General Virology. 2003;84: 307-17.
Liang S, Baibakov B and Horuzsko A. HLA-G inhibits the functions of murine dendritic cells via the PIR-B immune inhibitory receptor. European Journal of Immunology. 2002;32:2418-26.
Horuzsko A, Lenfant F, Munn DH and Mellor AL. Maturation of antigen presenting cells is compromised in HLA-G transgenic mice. International Immunology. 2001;13:385-94.
Horuzsko A, Portik-Dobos V, Hansen KA, Markowitz RB and Mellor A.L. Induction of HLA-G-specific human CD8+ T cell lines by stimulation across a polymorphism of HLA-G. Transplantation Proceedings. 1999;31:1860-63.
Padanyi A, Horuzsko A, Gyodi E, Reti M, Perner F, Petranyi GG. Long term related kidney graft survival in high-risk patients after monitored donor-specific transfusion protocol. Transplant International. 1998;11110-14.
Padanyi A, Horuzsko A, Gyodi E, Reti M, Pocsik E, Kotlan B, Perner F, Petranyi GG. Humoral and cell-mediated factors involved in the suppressive regulation induced by special blood derivates and their clinical relevance. Transplantation Proceedings.1998;30:3967-71.
Horuzsko A, Antoniou J, Tomlinson PD, Portik-Dobos V and Mellor AL. HLA-G functions as restriction element and a transplantation antigen in mice. International Immunology.1997;9:645-53.
Horuzsko A, Tomlinson PD, Strachan T, Mellor A.L. Transcription of the HLA-G transgenes commences shortly after implantation during embryonic development in mice. Immunology. 1994;83:324-28.
Petranyi Gy, Gyodi E and Horuzsko A. Kidney transplantation activity in Hungary. Hungarian Medical Journal. 1991;132:529-33.
Horuzsko A, Gyodi E, Reti M, Mayer K, Kassay M and Petranyi Gy. Selective effect of non-cytotoxic blocking alloantibodies produced after platelet transfusions on MLC, mitogen- and soluble antigen induced response of lymphocytes in human. Transplantation. 1990;50:497-501.
Horuzsko A, Gyodi E, Reti M, Onody K, Perner F, Kassay M and Petranyi Gy. Non-cytotoxic blocking antibodies and suppressor cells induced by donor-specific transfusions in healthy volunteers and potential kidney transplant recipients. Immunology Letters. 1990;26:127-30.
Szelenyi J, Paldi-Haris P, Paloczi K, Pocsik E, Horuzsko A, Klein M, Szobor A and Hollan S. Altered function and nicotinic acetylcholine receptor (nAChR) of lymphocytes in myasthenia gravis. International Journal of Immunopathology and Pharmacology. 1990;1:19-27.
Takacs K, Gyodi E, Horuzsko A, Foldi, Poros A and Petranyi Gy. The use of DNA level HLA-typing in bone marrow transplantations. Experimental Medicine. 1990;42:33-37.
Petranyi G Gy, Padanyi A, Horuzsko A, Reti M, Gyodi E and Perner F. Mixed lymphocyte culture-evidence that pre-transplant transfusion with platelets induced FcR and blocking antibody production similar to that induced by leukocyte transfusion. Transplantation. 1988;45:823-4.
Horuzsko AP, Yakovlev AM and Kamardin LN. Blast transformation under phytohemagglutinin action as an index of nonspecific lymphocyte reactivity in thyroid gland diseases. Problems of Endocrinology. 1980;26:14-17.
Horuzsko AP and Yakovlev AM. Dosage effect of specific antigen on the indices of the leukocyte migration inhibition reaction in thyroid gland diseases. Journal of Microbiology, Epidemiology and Immunobiology, 1979;10:49-53.
Kamardin LN, Yakovlev AM and Horuzsko AP. Leukocyte migration inhibition test in assessing autosensitization of the body in thyroid gland diseases. Problems of Endocrinology. 1977;23:32-35.