Institute of Experimental Immunology
Group Prof. Dr. Percy Knolle

1. Research overview
2. Research topics
3. Group members
4. Grant support
5. Principal investigator
6. Publications

Research overview

The focus of our research group is on the molecular and cellular mechanisms governing local immune control in the liver. The liver is a particular place where immune tolerance rather than immunity is induced. The liver is exposed to environmental antigens derived from the gastrointestinal tract and is instrumental in clearance of macromolecules as well as cells from the systemic circulation. Hepatic cell populations cooperate in order to meet the physiological tasks, i.e. metabolization and clearance, and immune function. The hepatic microanatomy is shaped to support these functional needs.

Blood flows through hepatic sinusoids, which are lined by liver sinusoidal endothelial cells (LSEC). The space of Disse between LSEC and hepatocytes is populated by myofibroblasts, stellate cells. Kupffer cells and NKT cells patrol the sinusoids. These cells create together with the unique blood-supply of the liver from the gastrointestinal tract create a special local micro-environment that contributes to the tolerogenic function of the liver (for review see Knolle and Gerken, Immunological Reviews 2000).

We have discovered that LSEC constitute a rather specialized population of organ-resident antigen-presenting cell, which bear resemblance with immature dendritic cells. LSEC present exogenous antigens on MHC II molecules to CD4 T cells and cross-present exogenous antigens even more efficiently on MHC I molecules to CD8 T cells. LSEC further constitutively express co-stimulatory molecules necessary to prime naive CD4 and CD8 T cells. In contrast to dendritic cells antigen presentation by LSEC to naive T cells leads to their proliferation but fails to induce a differentiation program. Importantly, naive CD8 T cells stimulated by LSEC are rendered anergic, as characterized by their inability to respond to antigen-specific restimulation with secretion of cytokines and cytotoxic effector function. Thus, the liver contributes induction of peripheral CD8 T cell tolerance.
We have identified two examples where induction of CD8 T cell tolerance by LSEC is of physiological importance.

 

Research topics

 

Oral tolerance

Blood derived from the gastrointestinal tract drains into the liver via the portal vein and thus delivers orally ingested antigens. We have demonstrated that LSEC cross-present oral antigens within 1 hour after oral ingestion to CD8 T cells. Adoptive transfer of LSEC isolated from mice fed orally with a model antigen into congenic mice led to development of CD8 T cell tolerance towards the orally fed antigen. Tolerance was characterized by absence of in vivo cytotoxic activity of CD8 T cells. This assigns a role for the liver and LSEC in maintenance of peripheral tolerance towards orally ingested antigens.

Tumor immune escape
The liver is also involved in elimination of apoptotic cells from the circulation, which is effected by cooperative action of Kupffer cells and LSEC. We observed that LSEC took up efficiently apoptotic bodies from the circulation and cross-presented antigens contained within apoptotic cell fragments to CD8 T cells. Because tumor cells metastasizing with the blood stream are efficiently eliminated in the liver by NK cells, we hypothesized that such initial tumor elimination may contribute to induction of subsequent immune tolerance. Indeed, LSEC cross-presenting apoptotic tumor cell material induced tumor-specific CD8 T cell tolerance. Hematogenous metastasis of tumor cells may thus confer a distinct growth advantage to tumor cells through induction of immune escape.

Molecular mechanisms of tolerance induction in CD8 T cells
Recently, we have identified the molecular mechanisms determining the induction of CD8 T cell tolerance through LSEC. Antigen-presentation to naive CD8 T cells elicits a maturation in LSEC that is characterized by increased expression of adhesion molecules promoting firm adhesion of T cells and more importantly a 10fold increase in the co-inhibitory molecule B7H1. Co-inhibitory signaling through B7H1-PD1 interaction results in a developmental program in CD8 T cells that finally results in development of tolerance. Importantly, tolerized T cells express significant levels of bcl2, which prevents induction of apoptosis. Thus, peripheral tolerance induced by LSEC is unique because it does not involve clonal deletion. The implication of such non-deletional tolerance for subsequent immune responses is currently under investigation.

Moreover, we have identified a novel mechanisms of local immune regulation in the liver. LSEC prevent in an antigen-non specific fashion stimulation of naive CD8 T cells by antigen-presenting dendritic cells. This immune-regulatory veto function of LSEC depends on physical interaction with DC/T cells and is characterized by reduced expression of co-stimulatory molecules CD80/86 and IL-12. However, further molecules are involved in inhibition of T cell priming because supplementation of CD28 or IL-12 signals does not rescue T cell stimulation. This finding sheds important new light on local immune regulation in the liver.
 

Ongoing research projects:

Current research activities in the lab concentrate on

1. the molecular mechanisms enabling most efficient cross-presentation by LSEC to CD8 T cells (in collaboration with the research group of C. Kurts)

2. epigenetic mechanisms of tolerance induction in CD8 T cells

3. the functional plasticity of LSEC in response to stimulation via pattern-recognition receptors

4. the role of LSEC in infection of the liver with hepatotropic viruses

5. cellular and molecular mechanisms of immune-mediated liver damage

6. regulation of immune cell function by nuclear receptors

Furthermore, two young investigators set up their research groups in the lab to work on the molecular mechanisms in induction and maintenance of CD8 T cell tolerance (L. Diehl) and PPAR-gamma mediated control of local immunity in the central nervous system (L. Klotz).
Together with the Core facility Flow cytometry and Cell Sorting within the SFB 704 we aim to generate new tools for multi-parameter analysis of immune cell function and to employ FACSorting to develop novel strategies for target molecule identification.

 

Group Members

Linda Diehl, PhD

Li-Rung Huang, PhD

Dirk Stabenow, PhD

Zeinab Abdullah, PhD

Bastian Höchst, PhD

Schröder, Matthias, PhD

Rike Schulte, PhD student

Jan Böttcher, PhD student

Frank Schildberg, PhD student

Marianne Frings, PhD student

Yvonne Gäbel, PhD student

Meike Welz, PhD

Silke Hegenbarth, research technician

Christina Metzger, research technician

Carolin Börner, research technician

Kati Riethausen, research technician

 

Grant support

DFG Sonderforschungsbereich 704

DFG Sonderforschungsbereich 670

DFG Graduiertenkolleg 804

NRW Forschungsschule

Deutsche Krebshilfe

EU Marie-Curie-Fellowship

Cooperation with industry

Helmholtz Alliance Immunotherapy for Cancer

BONFOR

BMBF Proketträger Jülich

 

Principal Investigator

Percy A. Knolle, MD

Specialist in Internal Medicine 
Full Professor of Molecular Medicine and Immunology

1982-88 Study of Medicine at the Universities of Frankfurt, Birmingham (UK), Paris, Strasbourg and Geneva

1988-1991 Experimental thesis (MD) at the German Cancer Research Center with Prof. S. Meuer

1991-1997 Clinical Training as specialist in Internal Medicine at the University Hospital Mainz with Prof. K.-H. Meyer zum Baschenfelde

1997-2002 Junior research group leader at the ZMBH with Prof. H. Schaller

Since 2002 Director Institute of Molecular Medicine and Experimental Immunology, University Hospital Bonn Head of BONFOR program at the Medical Faculty co-founder/co-speaker SFB 704 "Molecular mechanisms and chemical modulation of local immune regulation" Head of Steering Committee for the House of Experimental Therapy (HET)
 

Publications

Schrage, A., C. Loddenkemper, U. Erben, U. Lauer, G. Hausdorf, P. R. Jungblut, J. Johnson, P. A. Knolle, M. Zeitz, A. Hamann, and K. Klugewitz. 2008. Murine CD146 is widely expressed on endothelial cells and is recognized by the monoclonal antibody ME-9F1. Histochemistry and cell biology.

Schildberg, F. A., S. I. Hegenbarth, B. Schumak, A. Limmer, and P. A. Knolle. 2008. Liver sinusoidal endothelial cells veto CD8 T cell activation by antigen-presenting dendritic cells. European journal of immunology 38:957-967.

Diehl, L., A. Schurich, R. Grochtmann, S. Hegenbarth, L. Chen, and P. A. Knolle. 2008. Tolerogenic maturation of liver sinusoidal endothelial cells promotes B7-homolog 1-dependent CD8+ T cell tolerance. Hepatology 47:296-305.

Klotz, L., L. Diehl, I. Dani, H. Neumann, N. von Oppen, A. Dolf, E. Endl, T. Klockgether, B. Engelhardt, and P. Knolle. 2007. Brain endothelial PPARgamma controls inflammation-induced CD4+ T cell adhesion and transmigration in vitro. J Neuroimmunol 190:34-43.

Klotz, L., I. Dani, F. Edenhofer, L. Nolden, B. Evert, B. Paul, W. Kolanus, T. Klockgether, P. Knolle, and L. Diehl. 2007. Peroxisome proliferator-activated receptor gamma control of dendritic cell function contributes to development of CD4+ T cell anergy. J Immunol 178:2122-2131.

Fievez, L., C. Desmet, E. Henry, B. Pajak, S. Hegenbarth, V. Garze, F. Bex, F. Jaspar, P. Boutet, L. Gillet, A. Vanderplasschen, P. A. Knolle, O. Leo, M. Moser, P. Lekeux, and F. Bureau. 2007. STAT5 is an ambivalent regulator of neutrophil homeostasis. PLoS ONE 2:e727.

Burgdorf, S., A. Kautz, V. Bohnert, P. A. Knolle, and C. Kurts. 2007. Distinct pathways of antigen uptake and intracellular routing in CD4 and CD8 T cell activation. Science 316:612-616.

Wingender, G., B. Schumak, A. Schurich, J. E. Gessner, E. Endl, A. Limmer, and P. A. Knolle. 2006. Rapid and preferential distribution of blood-borne alphaCD3epsilonAb to the liver is followed by local stimulation of T cells and natural killer T cells. Immunology 117:117-126.

Wingender, G., N. Garbi, B. Schumak, F. Jungerkes, E. Endl, D. von Bubnoff, J. Steitz, J. Striegler, G. Moldenhauer, T. Tuting, A. Heit, K. M. Huster, O. Takikawa, S. Akira, D. H. Busch, H. Wagner, G. J. Hammerling, P. A. Knolle, and A. Limmer. 2006. Systemic application of CpG-rich DNA suppresses adaptive T cell immunity via induction of IDO. European journal of immunology 36:12-20.

Wingender, G., M. Berg, F. Jungerkes, L. Diehl, B. A. Sullivan, M. Kronenberg, A. Limmer, and P. A. Knolle. 2006. Immediate antigen-specific effector functions by TCR-transgenic CD8+ NKT cells. European journal of immunology 36:570-582.

Schmitz, V., F. Dombrowski, J. Prieto, C. Qian, L. Diehl, P. Knolle, T. Sauerbruch, W. H. Caselmann, U. Spengler, and L. Leifeld. 2006. Induction of murine liver damage by overexpression of CD40 ligand provides an experimental model to study fulminant hepatic failure. Hepatology 44:430-439.

Ryschich, E., P. Lizdenis, C. Ittrich, A. Benner, S. Stahl, A. Hamann, J. Schmidt, P. Knolle, B. Arnold, G. J. Hammerling, and R. Ganss. 2006. Molecular fingerprinting and autocrine growth regulation of endothelial cells in a murine model of hepatocellular carcinoma. Cancer Res 66:198-211.

Knolle, P. A. 2006. Involvement of the liver in the induction of CD8 T cell tolerance towards oral antigen. Z Gastroenterol 44:51-56.

Knolle, P. A. 2006. Cognate interaction between endothelial cells and T cells. Results Probl Cell Differ 43:151-173.

Beyer, M., M. Kochanek, T. Giese, E. Endl, M. R. Weihrauch, P. A. Knolle, S. Classen, and J. L. Schultze. 2006. In vivo peripheral expansion of naive CD4+CD25high FoxP3+ regulatory T cells in patients with multiple myeloma. Blood 107:3940-3949.

Berg, M., G. Wingender, D. Djandji, S. Hegenbarth, F. Momburg, G. Hammerling, A. Limmer, and P. Knolle. 2006. Cross-presentation of antigens from apoptotic tumor cells by liver sinusoidal endothelial cells leads to tumor-specific CD8+ T cell tolerance. European journal of immunology 36:2960-2970.

Viebig, N. K., U. Wulbrand, R. Forster, K. T. Andrews, M. Lanzer, and P. A. Knolle. 2005. Direct activation of human endothelial cells by Plasmodium falciparum-infected erythrocytes. Infect Immun 73:3271-3277.

Viebig, N. K., K. T. Andrews, Y. Kooyk, M. Lanzer, and P. A. Knolle. 2005. Evaluation of the role of the endocytic receptor L-SIGN for cytoadhesion of Plasmodium falciparum-infected erythrocytes. Parasitol Res 96:247-252.

Uhrig, A., R. Banafsche, M. Kremer, S. Hegenbarth, A. Hamann, M. Neurath, G. Gerken, A. Limmer, and P. A. Knolle. 2005. Development and functional consequences of LPS tolerance in sinusoidal endothelial cells of the liver. J Leukoc Biol 77:626-633.

Limmer, A., J. Ohl, G. Wingender, M. Berg, F. Jungerkes, B. Schumak, D. Djandji, K. Scholz, A. Klevenz, S. Hegenbarth, F. Momburg, G. J. Hammerling, B. Arnold, and P. A. Knolle. 2005. Cross-presentation of oral antigens by liver sinusoidal endothelial cells leads to CD8 T cell tolerance. European journal of immunology 35:2970-2981.

Klotz, L., M. Schmidt, T. Giese, M. Sastre, P. Knolle, T. Klockgether, and M. T. Heneka. 2005. Proinflammatory stimulation and pioglitazone treatment regulate peroxisome proliferator-activated receptor gamma levels in peripheral blood mononuclear cells from healthy controls and multiple sclerosis patients. J Immunol 175:4948-4955.

Beyer, M., M. Kochanek, K. Darabi, A. Popov, M. Jensen, E. Endl, P. A. Knolle, R. K. Thomas, M. von Bergwelt-Baildon, S. Debey, M. Hallek, and J. L. Schultze. 2005. Reduced frequencies and suppressive function of CD4+CD25hi regulatory T cells in patients with chronic lymphocytic leukemia after therapy with fludarabine. Blood 106:2018-2025.

Weber, O., A. Siegling, A. Friebe, A. Limmer, T. Schlapp, P. Knolle, A. Mercer, H. Schaller, and H. D. Volk. 2003. Inactivated parapoxvirus ovis (Orf virus) has antiviral activity against hepatitis B virus and herpes simplex virus. J Gen Virol 84:1843-1852.

Knolle, P. A., and A. Limmer. 2003. Control of immune responses by savenger liver endothelial cells. Swiss Med Wkly 133:501-506.

Andrews, K. T., N. K. Viebig, F. Wissing, N. Klatt, N. Oster, H. Wickert, P. Knolle, and M. Lanzer. 2003. A human schwannoma cell line supports the in vitro adhesion of Plasmodium falciparum infected erythrocytes to chondroitin-4-sulfate. Parasitol Res 89:188-193.

Sacher, T., P. Knolle, T. Nichterlein, B. Arnold, G. J. Hammerling, and A. Limmer. 2002. CpG-ODN-induced inflammation is sufficient to cause T-cell-mediated autoaggression against hepatocytes. European journal of immunology 32:3628-3637.

Klugewitz, K., F. Blumenthal-Barby, A. Schrage, P. A. Knolle, A. Hamann, and I. N. Crispe. 2002. Immunomodulatory effects of the liver: deletion of activated CD4+ effector cells and suppression of IFN-gamma-producing cells after intravenous protein immunization. J Immunol 169:2407-2413.

Seebach, J. D., M. K. Schneider, C. A. Comrack, A. LeGuern, S. A. Kolb, P. A. Knolle, S. Germana, H. DerSimonian, C. LeGuern, and D. H. Sachs. 2001. Immortalized bone-marrow derived pig endothelial cells. Xenotransplantation 8:48-61.

Limmer, A., and P. A. Knolle. 2001. Liver sinusoidal endothelial cells: a new type of organ-resident antigen-presenting cell. Arch Immunol Ther Exp (Warsz) 49 Suppl 1:S7-11.

Knolle, P. A., and A. Limmer. 2001. Neighborhood politics: the immunoregulatory function of organ-resident liver endothelial cells. Trends Immunol 22:432-437.

Breiner, K. M., H. Schaller, and P. A. Knolle. 2001. Endothelial cell-mediated uptake of a hepatitis B virus: a new concept of liver targeting of hepatotropic microorganisms. Hepatology 34:803-808.

Bashirova, A. A., T. B. Geijtenbeek, G. C. van Duijnhoven, S. J. van Vliet, J. B. Eilering, M. P. Martin, L. Wu, T. D. Martin, N. Viebig, P. A. Knolle, V. N. KewalRamani, Y. van Kooyk, and M. Carrington. 2001. A dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN)-related protein is highly expressed on human liver sinusoidal endothelial cells and promotes HIV-1 infection. J Exp Med 193:671-678.

Banafsche, R., L. Gunther, J. U. Nefflen, S. Moutsiou, P. A. Knolle, C. Herfarth, and E. Klar. 2001. NF-kappa B antisense oligonucleotides reduce leukocyte-endothelial interaction in hepatic ischemia-reperfusion. Transplant Proc 33:3726-3727.

Limmer, A., J. Ohl, C. Kurts, H. G. Ljunggren, Y. Reiss, M. Groettrup, F. Momburg, B. Arnold, and P. A. Knolle. 2000. Efficient presentation of exogenous antigen by liver endothelial cells to CD8+ T cells results in antigen-specific T-cell tolerance. Nat Med 6:1348-1354.

Knolle, P. A., and G. Gerken. 2000. Local control of the immune response in the liver. Immunol Rev 174:21-34.

Hegenbarth, S., R. Gerolami, U. Protzer, P. L. Tran, C. Brechot, G. Gerken, and P. A. Knolle. 2000. Liver sinusoidal endothelial cells are not permissive for adenovirus type 5. Hum Gene Ther 11:481-486.

Knolle, P. A., E. Schmitt, S. Jin, T. Germann, R. Duchmann, S. Hegenbarth, G. Gerken, and A. W. Lohse. 1999. Induction of cytokine production in naive CD4(+) T cells by antigen-presenting murine liver sinusoidal endothelial cells but failure to induce differentiation toward Th1 cells. Gastroenterology 116:1428-1440.

Knolle, P. A., T. Germann, U. Treichel, A. Uhrig, E. Schmitt, S. Hegenbarth, A. W. Lohse, and G. Gerken. 1999. Endotoxin down-regulates T cell activation by antigen-presenting liver sinusoidal endothelial cells. J Immunol 162:1401-1407.

Duchmann, R., E. May, M. Heike, P. Knolle, M. Neurath, and K. H. Meyer zum Buschenfelde. 1999. T cell specificity and cross reactivity towards enterobacteria, bacteroides, bifidobacterium, and antigens from resident intestinal flora in humans. Gut 44:812-818.

Knolle, P. A., A. Uhrig, U. Protzer, M. Trippler, R. Duchmann, K. H. Meyer zum Buschenfelde, and G. Gerken. 1998. Interleukin-10 expression is autoregulated at the transcriptional level in human and murine Kupffer cells. Hepatology 27:93-99.

Knolle, P. A., A. Uhrig, S. Hegenbarth, E. Loser, E. Schmitt, G. Gerken, and A. W. Lohse. 1998. IL-10 down-regulates T cell activation by antigen-presenting liver sinusoidal endothelial cells through decreased antigen uptake via the mannose receptor and lowered surface expression of accessory molecules. Clin Exp Immunol 114:427-433.

Knolle, P. A., S. Kremp, T. Hohler, F. Krummenauer, P. Schirmacher, and G. Gerken. 1998. Viral and host factors in the prediction of response to interferon-alpha therapy in chronic hepatitis C after long-term follow-up. J Viral Hepat 5:399-406.

Knolle, P. A., E. Loser, U. Protzer, R. Duchmann, E. Schmitt, K. H. zum Buschenfelde, S. Rose-John, and G. Gerken. 1997. Regulation of endotoxin-induced IL-6 production in liver sinusoidal endothelial cells and Kupffer cells by IL-10. Clin Exp Immunol 107:555-561.

Knolle, P. A., A. J. Eckardt, U. Protzer-Knolle, P. Schirmacher, H. P. Dienes, K. H. Meyer zum Buschenfelde, and G. Gerken. 1997. Circulating ICAM-1 (sCD54) and LFA-3 (sCD58) in chronic hepatitis B--a longitudinal study in patients treated with interferon-alpha. Z Gastroenterol 35:459-467.

Lohse, A. W., P. A. Knolle, K. Bilo, A. Uhrig, C. Waldmann, M. Ibe, E. Schmitt, G. Gerken, and K. H. Meyer Zum Buschenfelde. 1996. Antigen-presenting function and B7 expression of murine sinusoidal endothelial cells and Kupffer cells. Gastroenterology 110:1175-1181.

Knolle, P. A., G. Gerken, E. Loser, H. P. Dienes, F. Gantner, G. Tiegs, K. H. Meyer zum Buschenfelde, and A. W. Lohse. 1996. Role of sinusoidal endothelial cells of the liver in concanavalin A-induced hepatic injury in mice. Hepatology 24:824-829.

Knolle, P., J. Schlaak, A. Uhrig, P. Kempf, K. H. Meyer zum Buschenfelde, and G. Gerken. 1995. Human Kupffer cells secrete IL-10 in response to lipopolysaccharide (LPS) challenge. J Hepatol 22:226-229.

 

Reviews and book sections

Knolle PA. 2006. Involvement of the liver in the induction of CD8 T cell tolerance towards oral antigen. Z Gastroenterol 44: 51-6
Knolle PA, Limmer A. 2003. Control of immune responses by savenger liver endothelial cells. Swiss Med Wkly 133: 501-6
Knolle PA, Limmer A. 2001. Neighborhood politics: the immunoregulatory function of organ-resident liver endothelial cells. Trends Immunol 22: 432-7
Knolle PA, Gerken G. 2000. Local control of the immune response in the liver. Immunol Rev 174: 21-34

Knolle PA: "Cognate interaction between endothelial cells and T cells". In Cell communication in the nervous and immune system. 2006 Edited by B. Schraven
Knolle PA: "The Liver and the immune system", in Zakim and Boyer`s Hepatology A textbook of liver disease, Fifth edition 2006, edited by Thomas D. Boyer, Teresa L. Wright, Michael P. Manns.
Knolle PA: "Role and function of liver sinusoidal endothelial cells", Liver Immunology, edited by Vierling, Gershwin and Manns. Second edition 2006.
Knolle PA: "Antigen entry routes - where foreign invaders meet antigen presenting cells", in Antigen presenting cells, 2005 edited by Harald Kropshofer and Anne Vogt
Knolle PA: "The liver and its contribution to oral tolerance". Gut-Liver interactions: basic and clinical concepts Falk Symposium 146 2005.