Prof Vincenzo Cerundolo
| Research Area: | Immunology |
|---|---|
| Keywords: | vaccination strategies, NKT cells, dendritic cells, innate immunity, T cells and clinical trials |
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The principal aim of the Research in my laboratory is to gain a better understanding of the mechanisms that control the cell-cell interplay required for optimal expansion and activation of tumour-specific T cell populations and to apply this knowledge to the development of better treatment strategies in cancer patients. Research in my laboratory is divided into three complementary areas:
- Analysis of tumour-specific immune responses in melanoma patients and the role of the tumour micro-environment in hampering tumour-specific immune responses;
- Structural, kinetic and functional analyses of invariant NKT (iNKT) cell activation;
- Clinical trial vaccine programme in melanoma patients.
1) Analysis of the Tumour-Specific Immune Response
By using HLA class I tetramers we have gained an understanding of the tumour-specific immune response, and have been able to show that in some patients with metastatic melanoma there are expanded populations of tumour-specific cytotoxic T lymphocytes.
We have recently started a research programme focused on the role of the tumour micro-environment in suppressing tumour-specific immune responses. The results of our studies have demonstrated the presence of IL-10 secreting neutrophils in a large proportion of melanoma patients. These cells suppress proliferation and activity of tumour-specific T cell responses (De Santo et al. 2011). We have extended these results by demonstrating that binding of Serum Amyloid A (SAA) to Formyl-Peptide Receptor 2 controls the plasticity of neutrophil differentiation by triggering IL-10 synthesis and promoting their ability to interact with iNKT cells via CD1d molecules. CD1d and CD40 dependent interaction of IL-10 secreting neutrophils with iNKT cells results in reduced IL-10 and enhanced IL-12 production, thus limiting their suppressive activity (De Santo et al. 2011). The observation that melanomas promote differentiation of IL-10 secreting neutrophils by producing SAA highlights the importance of harnessing iNKT cells in therapeutic strategies to reduce the frequency of immunosuppressive neutrophils and to restore tumour specific immune responses.
In addition to optimise strategies to increase the frequency of tumour-specific T cells, it is important to characterise further the mechanisms that control the ability of antigen specific T cells to home to defined tissues, as this would facilitate the development of strategies to improve homing of T cells into different tumour types. Over the last 2 years, we have initiated a programme to studyhow tissue stroma can modulate the expression of tissue homing receptors. It is known that the production of retinoic acid (RA) by dendritic cells (DCs) is critical for driving the development of gut-tropic immune responses; however, the factors that regulate RA synthesis by DCs remain poorly defined. We have recently demonstrated the role of prostaglandin E2 (PGE2) in blocking the expression of the retinal dehydrogenases (RALDH), the enzymes responsible for converting vitamin A into RA, and abrogating their ability to induce CCR9 expression upon T cell priming (Stock et al. 2011).
Recently we have been characterising a novel tryptophan transporter, up-regulated in cells expressing the tryptophan degrading enzyme indoleamine-2,3-dioxygenase (IDO) (Silk et al. 2011).
2) Structural, Kinetic and Functional Analyses of iNKT Cell Activation
We and others have recently demonstrated that stimulating iNKT cells in vivo with the specific synthetic ligand alpha-GalCer served to significantly enhance immune responses to protein-based vaccines. We have demonstrated that co-injection of iNKT cell agonists together with antigenic proteins enhances antigen-specific T cell responses. This enhancement is dependent on the involvement of iNKT cells and CD1d molecules and requires CD40 signalling. Thus, iNKT cells exert a significant influence on the efficacy of immune responses to soluble antigen by modulating DC function, as recently reviewed. Our results are consistent with the general concept that there is considerable immunostimulatory power in the integration of iNKT-mediated and TLR-mediated signals to DCs (Salio et al. 2007; McCarthy et al. 2007). Understanding this level of regulation will be important in designing appropriate, and hence effective, vaccines.
More recently, in collaboration with Facundo Batista (Cancer Research Institute), we have started to analyse the cross-talk between iNKT cells and B cells (Barral et al. 2010).
We previously developed two novel protocols for the refolding of denatured CD1 molecules, based either on the use of short mono-alkyl detergent molecules or on oxidative refolding chromatography. Techniques developed in the laboratory have enabled the use of ‘refolded’ CD1 molecules to monitor the frequency and phenotype of NKT cells in health and disease. Together with knowledge of the crystal structures of CD1d and CD1b loaded with different lipid antigens (solved in collaboration with Prof. E. Y. Jones, University of Oxford) it has been possible to study both in vitro and in vivo activation of NKT cells, and their effect on the adaptive immune responses.
3) Clinical Trial Programme in Melanoma Patients
My group has been developing a very active clinical trial programme to translate our preclinical vaccination strategies into phase I/II clinical trials and several cancer vaccines are currently being compared in the clinic.
| Name | Department | Institution | Country |
|---|---|---|---|
| Prof E. Yvonne Jones | Structural Biology | Oxford University | UK |
| Adrian Harris | University of Oxford | UK | |
| Facundo Batista | Cancer Research UK | UK | |
| Frances Platt | University of Oxford | UK |
2011. IDO induces expression of a novel tryptophan transporter in mouse and human tumor cells. J Immunol, 187 (4), pp. 1617-1625. Read abstract | Read more
IDO is the rate-limiting enzyme in the kynurenine pathway, catabolizing tryptophan to kynurenine. Tryptophan depletion by IDO-expressing tumors is a common mechanism of immune evasion inducing regulatory T cells and inhibiting effector T cells. Because mammalian cells cannot synthesize tryptophan, it remains unclear how IDO(+) tumor cells overcome the detrimental effects of local tryptophan depletion. We demonstrate that IDO(+) tumor cells express a novel amino acid transporter, which accounts for ∼50% of the tryptophan uptake. The induced transporter is biochemically distinguished from the constitutively expressed tryptophan transporter System L by increased resistance to inhibitors of System L, resistance to inhibition by high concentrations of most amino acids tested, and high substrate specificity for tryptophan. Under conditions of low extracellular tryptophan, expression of this novel transporter significantly increases tryptophan entry into IDO(+) tumors relative to tryptophan uptake through the low-affinity System L alone, and further decreases tryptophan levels in the microenvironment. Targeting this additional tryptophan transporter could be a way of pharmacological inhibition of IDO-mediated tumor escape. These findings highlight the ability of IDO-expressing tumor cells to thrive in a tryptophan-depleted microenvironment by expressing a novel, highly tryptophan-specific transporter, which is resistant to inhibition by most other amino acids. The additional transporter allows tumor cells to strike the ideal balance between supply of tryptophan essential for their own proliferation and survival, and depleting the extracellular milieu of tryptophan to inhibit T cell proliferation. Hide abstract
2011. Prostaglandin E2 suppresses the differentiation of retinoic acid-producing dendritic cells in mice and humans. J Exp Med, 208 (4), pp. 761-773. Read abstract | Read more
The production of retinoic acid (RA) by dendritic cells (DCs) is critical for the induction of gut-tropic immune responses by driving the expression of intestinal-specific homing receptors, such as α4β7 and CCR9, upon T and B cell activation. However, how RA production is regulated during DC development remains unclear. We describe an unexpected role for prostaglandin E2 (PGE2) as a negative regulator of retinal dehydrogenases (RALDH), the enzymes responsible for RA synthesis. The presence of PGE2 during DC differentiation inhibited RALDH expression in mouse and human DCs, abrogating their ability to induce CCR9 expression upon T cell priming. Furthermore, blocking PGE2 signaling increased the frequency of RALDH(+) DCs in vitro, and reducing PGE2 synthesis in vivo promoted the systemic emergence of RA-producing DCs and the priming of CCR9(+) T cells in nonintestinal sites such as the spleen. Finally, we found that PGE2 stimulated the expression of the inducible cyclic AMP early repressor, which appears to directly inhibit RALDH expression in DCs, thus providing mechanistic insight into how PGE2 signaling down-modulates RALDH. Given the role of PGE2 in regulating the development of RA-producing DCs, modulating this pathway may prove a novel means to control the development of gut-tropic immune responses. Hide abstract
2011. Reply to "Failure to detect production of IL-10 by activated human neutrophils". Nat Immunol, 12 (11), pp. 1018-1020. | Read more
2010. Invariant NKT cells modulate the suppressive activity of IL-10-secreting neutrophils differentiated with serum amyloid A. Nat Immunol, 11 (11), pp. 1039-1046. Read abstract | Read more
Neutrophils are the main effector cells during inflammation, but they can also control excessive inflammatory responses by secreting anti-inflammatory cytokines. However, the mechanisms that modulate their plasticity remain unclear. We now show that systemic serum amyloid A 1 (SAA-1) controls the plasticity of neutrophil differentiation. SAA-1 not only induced anti-inflammatory interleukin 10 (IL-10)-secreting neutrophils but also promoted the interaction of invariant natural killer T cells (iNKT cells) with those neutrophils, a process that limited their suppressive activity by diminishing the production of IL-10 and enhancing the production of IL-12. Because SAA-1-producing melanomas promoted differentiation of IL-10-secreting neutrophils, harnessing iNKT cells could be useful therapeutically by decreasing the frequency of immunosuppressive neutrophils and restoring tumor-specific immune responses. Hide abstract
2010. CD169(+) macrophages present lipid antigens to mediate early activation of iNKT cells in lymph nodes. Nat Immunol, 11 (4), pp. 303-312. Read abstract | Read more
Invariant natural killer T cells (iNKT cells) are involved in the host defense against microbial infection. Although it is known that iNKT cells recognize glycolipids presented by CD1d, how and where they encounter antigen in vivo remains unclear. Here we used multiphoton microscopy to visualize the dynamics and activation of iNKT cells in lymph nodes. After antigen administration, iNKT cells became confined in a CD1d-dependent manner in close proximity to subcapsular sinus CD169(+) macrophages. These macrophages retained, internalized and presented lipid antigen and were required for iNKT cell activation, cytokine production and population expansion. Thus, CD169(+) macrophages can act as true antigen-presenting cells controlling early iNKT cell activation and favoring the fast initiation of immune responses. Hide abstract
2010. Ca2+ release from the endoplasmic reticulum of NY-ESO-1-specific T cells is modulated by the affinity of TCR and by the use of the CD8 coreceptor. J Immunol, 184 (4), pp. 1829-1839. Read abstract | Read more
Although several cancer immunotherapy strategies are based on the use of analog peptides and on the modulation of the TCR affinity of adoptively transferred T cells, it remains unclear whether tumor-specific T cell activation by strong and weak TCR stimuli evoke different Ca(2+) signatures from the Ca(2+) intracellular stores and whether the amplitude of Ca(2+) release from the endoplasmic reticulum (ER) can be further modulated by coreceptor binding to peptide/MHC. In this study, we combined functional, structural, and kinetic measurements to correlate the intensity of Ca(2+) signals triggered by the stimulation of the 1G4 T cell clone specific to the tumor epitope NY-ESO-1(157-165). Two analogs of the NY-ESO-1(157-165) peptide, having similar affinity to HLA-A2 molecules, but a 6-fold difference in binding affinity for the 1G4 TCR, resulted in different Ca(2+) signals and T cell activation. 1G4 stimulation by the stronger stimulus emptied the ER of stored Ca(2+), even in the absence of CD8 binding, resulting in sustained Ca(2+) influx. In contrast, the weaker stimulus induced only partial emptying of stored Ca(2+), resulting in significantly diminished and oscillatory Ca(2+) signals, which were enhanced by CD8 binding. Our data define the range of TCR/peptide MHC affinities required to induce depletion of Ca(2+) from intracellular stores and provide insights into the ability of T cells to tailor the use of the CD8 coreceptor to enhance Ca(2+) release from the ER. This, in turn, modulates Ca(2+) influx from the extracellular environment, ultimately controlling T cell activation. Hide abstract
2008. Invariant NKT cells reduce the immunosuppressive activity of influenza A virus-induced myeloid-derived suppressor cells in mice and humans. J Clin Invest, 118 (12), pp. 4036-4048. Read abstract | Read more
Infection with influenza A virus (IAV) presents a substantial threat to public health worldwide, with young, elderly, and immunodeficient individuals being particularly susceptible. Inflammatory responses play an important role in the fatal outcome of IAV infection, but the mechanism remains unclear. We demonstrate here that the absence of invariant NKT (iNKT) cells in mice during IAV infection resulted in the expansion of myeloid-derived suppressor cells (MDSCs), which suppressed IAV-specific immune responses through the expression of both arginase and NOS, resulting in high IAV titer and increased mortality. Adoptive transfer of iNKT cells abolished the suppressive activity of MDSCs, restored IAV-specific immune responses, reduced IAV titer, and increased survival rate. The crosstalk between iNKT and MDSCs was CD1d- and CD40-dependent. Furthermore, IAV infection and exposure to TLR agonists relieved the suppressive activity of MDSCs. Finally, we extended these results to humans by demonstrating the presence of myeloid cells with suppressive activity in the PBLs of individuals infected with IAV and showed that their suppressive activity is substantially reduced by iNKT cell activation. These findings identify what we believe to be a novel immunomodulatory role of iNKT cells, which we suggest could be harnessed to abolish the immunosuppressive activity of MDSCs during IAV infection. Hide abstract
2008. Cutting edge: nonglycosidic CD1d lipid ligands activate human and murine invariant NKT cells. J Immunol, 180 (10), pp. 6452-6456. Read abstract
Invariant NKT cells (iNKT cells) recognize CD1d/glycolipid complexes. We demonstrate that the nonglycosidic compound threitolceramide efficiently activates iNKT cells, resulting in dendritic cell (DC) maturation and the priming of Ag-specific T and B cells. Threitolceramide-pulsed DCs are more resistant to iNKT cell-dependent lysis than alpha-galactosylceramide-pulsed DCs due to the weaker affinity of the human iNKT TCR for CD1d/ threitolceramide than CD1d/alpha-galactosylceramide complexes. iNKT cells stimulated with threitolceramide also recover more quickly from activation-induced anergy. Kinetic and functional experiments showed that shortening or lengthening the threitol moiety by one hydroxymethylene group modulates ligand recognition, as human and murine iNKT cells recognize glycerolceramide and arabinitolceramide differentially. Our data broaden the range of potential iNKT cell agonists. The ability of these compounds to assist the priming of Ag-specific immune responses while minimizing iNKT cell-dependent DC lysis makes them attractive adjuvants for vaccination strategies. Hide abstract
2007. Modulation of human natural killer T cell ligands on TLR-mediated antigen-presenting cell activation. Proc Natl Acad Sci U S A, 104 (51), pp. 20490-20495. Read abstract | Read more
Invariant natural killer T (iNKT) cells are a subset of nonconventional T cells recognizing endogenous and/or exogenous glycolipid antigens in the context of CD1d molecules. It remains unclear whether innate stimuli can modify the profile of endogenous lipids recognized by iNKT cells on the surface of antigen-presenting cells (APCs). We report that activation of human APCs by Toll-like receptor ligands (TLR-L) modulates the lipid biosynthetic pathway, resulting in enhanced recognition of CD1d-associated lipids by iNKT cells, as defined by IFN-gamma secretion. APC-derived soluble factors further increase CD1d-restricted iNKT cell activation. Finally, using soluble tetrameric iNKT T cell receptors (TCR) as a staining reagent, we demonstrate specific up-regulation of CD1d-bound ligand(s) on TLR-mediated APC maturation. The ability of innate stimuli to modulate the lipid profile of APCs resulting in iNKT cell activation and APC maturation underscores the role of iNKT cells in assisting priming of antigen-specific immune responses. Hide abstract
2007. The length of lipids bound to human CD1d molecules modulates the affinity of NKT cell TCR and the threshold of NKT cell activation. J Exp Med, 204 (5), pp. 1131-1144. Read abstract | Read more
CD1d-restricted lymphocytes recognize a broad lipid range. However, how CD1d-restricted lymphocytes translate T cell receptor (TCR) recognition of lipids with similar group heads into distinct biological responses remains unclear. Using a soluble invariant NKT (iNKT) TCR and a newly engineered antibody specific for alpha-galactosylceramide (alpha-GalCer)-human CD1d (hCD1d) complexes, we measured the affinity of binding of iNKT TCR to hCD1d molecules loaded with a panel of alpha-GalCer analogues and assessed the rate of dissociation of alpha-GalCer and alpha-GalCer analogues from hCD1d molecules. We extended this analysis by studying iNKT cell synapse formation and iNKT cell activation by the same panel of alpha-GalCer analogues. Our results indicate the unique role of the lipid chain occupying the hCD1d F' channel in modulating TCR binding affinity to hCD1d-lipid complexes, the formation of stable immunological synapse, and cell activation. These data are consistent with previously described conformational changes between empty and loaded hCD1d molecules (Koch, M., V.S. Stronge, D. Shepherd, S.D. Gadola, B. Mathew, G. Ritter, A.R. Fersht, G.S. Besra, R.R. Schmidt, E.Y. Jones, and V. Cerundolo. 2005. Nat. Immunol 6:819-826), suggesting that incomplete occupation of the hCD1d F' channel results in conformational differences at the TCR recognition surface. This indirect effect provides a general mechanism by which lipid-specific lymphocytes are capable of recognizing both the group head and the length of lipid antigens, ensuring greater specificity of antigen recognition. Hide abstract
Molecular mechanisms controlling lipid antigen presentation to invariant natural killer T cells (iNKT)
Background: It is becoming clear that harnessing the interaction between the innate and adaptive arms of the immune system is of importance to optimise vaccination strategies against cancer and foreign pathogens. Over the last few years, it has emerged that invariant Natural Killer T cells bridge the two arms of the immune system and that their activation can be used to jump start antigen specific immune responses. This project is focused on the understanding of the molecular mechanisms by ...
The role of IDO and nutrient transporters in tumour immunity
Background: Understanding the molecular basis controlling the cross-talk between tumours and immune cells is important to identify strategies to overcome tumour immunosuppression. The rate-limiting enzyme in the immunoregulatory kynurenine pathway is indoleamine 2,3-dioxygenase (IDO), which converts the essential amino acid tryptophan to downstream metabolites. In recent years, IDO has been shown to be important in the regulation of a number of immune processes including at the ...
Virus sensing by the innate immune receptor MDA5
Background Virus infection triggers a multitude of immune responses. Detection of virus presence by the innate immune system is a crucial event in this process (Pichlmair et al. 2007). This can be mediated by germ-line encoded receptors that signal for the induction of innate immune response genes. Some of these receptors sense nucleic acids. For example, RIG-I-like receptors detect RNA molecules in the cytoplasm. Previously, we have shown that RIG-I recognises RNA genomes of viruses such as ...
Analysis of lipid loading onto CD1 molecules by super-resolution STED microscopy
Background T-cells play a central role in cell-mediated immunity. Their immune-modulatory properties are activated by the binding of T-cell receptors (TCR) to antigen complexes on the membrane surface of accessory or antigen-presenting cells (APC). iNKT cells are an exceptional sub-population of T-cells, since their activation is restricted to the lipid-antigen presenting glycoprotein agonist CD1d. Paradoxically, effector functions of iNKT are varied and they can lead to suppressed or ...
Imaging the distribution and kinetics of virus detection by innate immune receptors with super-resolution STED microscopy
Background Virus infection can be detected by certain cell-associated pattern recognition receptors. Interesting examples are RIG-I-like receptors, a family of helicase proteins that recognise viral RNA in the cytoplasm of infected cells. These pattern recognition receptors signal for the induction of type I interferons, a group of important anti-viral cytokines that trigger protective defense pathways of the immune system . Upon sensing virus presence, RIG-I and the related receptor MDA5 ...
