Major discoveries


Immunopharmacology of cell death. During my first steps as a principal investigator we observed that interleukin-2 (IL-2) can break peripheral T cell tolerance by reversing the anergy of self-reactive T lymphocytes, hence explaining the mechanism through which high-dose IL-2 stimulates anticancer immunity. We found that endogenous or exogenous glucocorticoids cause the deletion of activated T cells in vivo, thereby mediating strong immunosuppressive effects. Moreover, we discovered that pertussis-toxin-inhibitable receptors regulate the activation-induced cell death of innate and cognate immune effectors.

Principal references: Andreu-Sanchez et al.,  J Exp Med. 1991; Kroemer et al., Lancet 1991. Gonzalo et al., J Exp Med. Ramirez et al.,. J Exp Med. 1994

 

Mitochondrial cell death control. We discovered that, in programmed cell death, mitochondrial membrane permeabilization constitutes the point-of-no-return of the lethal process and hence defines the apoptotic checkpoint. This discovery has initiated a scientific revolution in thus far that it led to an operational redefinition of apoptosis, changed the method of apoptosis detection, and conditioned the theoretical framework allowing for the ordering of pro-apoptotic signaling molecules. Instead of considering apoptosis as a process dominated by proteases and nucleases, cell death is now viewed as a process that is largely controlled by mitochondria. This has far-reaching implications for the therapeutic manipulation of cell death, including the chemotherapeutic induction of cell death in cancer cells, which can be achieved by directly triggering mitochondrial permeabilization, as well as for the prevention of unwarranted cell death in stroke and infarction, which only can be achieved when targeting pre-mitochondrial or mitochondrial (but not post-mitochondrial) events. We have explored the fine mechanisms of mitochondrial cell death control, as well as the molecular pathways that explain the inhibition of cell death in cancer cells, upstream of or at the level of mitochondria. We observed that pro- and anti-apoptotic proteins of the Bcl-2 family regulate mitochondrial membrane permeability through interactions with proteins from the ATP synthasome and lipids. We also cloned and characterized the mitochondrial apoptosis-inducing factor (AIF), which turned out to play a major role in the assembly of the respiratory chain complex I, as well as in caspase-independent neuronal cell death.

Dedicated Editorial Comments: Cell Cycle. 2011, Cell Death Differ. 2011, EMBO J. 2011, Faculty of 1000 (http://www.facultyof1000.com), Front. Oncol. 2013, Hepatology. 2011, J Exp Med.. 1996, Nature. 1999, Nat. Cell Biol. 1999, Nat. Cell Biol. 2002, Nat. Rev. Mol. Cell Biol. 2001, Nat. Rev. Mol. Cell Biol.. 2011, Science. 1998, Science. 2001, Science. 2001, SciBX. 2008 SciBX 2008, The Scientist. 2001, The Scientist. 2004. Interviews: Cancer Biol. Ther. 2007, Cell Death Differ 2004, Science Watch (www.sciencewatch.com). Principal references: Zamzami et al., J Exp Med. 1995; Zamzami et al., J Exp Med. 1995; Zamzami et al., J Exp Med. 1996; Marchetti et al., J Exp Med. 1996; Susin et al., J Exp Med. 1996; Kroemer, Nat Med. 1997; Susin et al., J Exp Med. 1997; Marzo Iet al., J Exp Med. 1998; Marzo et al., Science. 1998; Susin et al., J Exp Med. 1999; Susin et al., Nature. 1999; Kroemer and Reed. Nat Med. 2000; Brenner and Kroemer., Science. 2000; Susin et al., J Exp Med. 2000; Joza et al., Nature. 2001; Ravagnan et al., Nat Cell Biol. 2001; Green and Kroemer. Science. 2004; Vahsen et al., EMBO J. 2004; Kroemer et al., Physiol Rev. 2007; Zhu et al., J Exp Med. 2007; Kroemer and Pouyssegur. Cancer Cell. 2008; Zischka et l.,  J Clin Invest 2011; Buttner et al., EMBO J. 2011; Green et al., Science 2011; Galluzzi L, et al., Nat Cell Biol. 2014; Green et al., Science. 2014; Hangen et al., Mol Cell. 2015

 

Mechanisms of HIV-1-induced apoptosis. We discovered that human immunodeficiency virus (HIV-1) causes mitochondrial dysfunctions of circulating lymphocytes and that HIV-1 can induce apoptosis via a variety of mechanisms, one of which involves Vpr, a soluble HIV-1 encoded accessory protein that can target mitochondria. We also discovered that vMIA, a protein from human cytomegalovirus (hCMV) can specifically target mitochondrial proteins to inhibit apoptosis and oxidative phosphorylation. We deciphered the molecular cascade through which HIV-1 induced cell-to-cell fusions leads to syncytial apoptosis, and we confirmed that this chain of events (with activation of a defined series of kinases and transcription factors) is activated in lymphoid tissues and brains from patients with AIDS. We found that clinically used HIV-1 protease inhibitors can mediate cytoprotective effects in vivo, for instance in the context of stroke and retinal detachment. This effect involves the inhibition of lethal mitochondrial membrane permeabilization. Finally, we defined several new pharmacological targets whose inhibition prevents HIV-1 infection of host cells: pannexin 1, purinergic P2Y2 receptors and the tyrosine kinase Pyk2.

Dedicated Editorial Comments: Blood 1996; Cell Death Differ. 2004; Faculty of 1000 (http://www.facultyof1000.com); Journal Exp. Med. 2001; Nat. Immunol. 2011, and SciBX 2011. Principal references: Macho et al., J Exp Med. 2000; Ferri et al., J Exp Med. 2000; Boya et al., EMBO J. 2001; Castedo et al., J Exp Med. 2001; Castedo et al., EMBO J. 2002; Castedo et al., J  Exp Med. 2002; Perfettini et al., J Exp Med. 2004; Perfettini et al., J Exp Med. 2005; Weaver et al., J Clin Invest. 2005; Poncet  et al., J Cell Biol. 2006; Hisatomi et al., J Clin Invest. 2008; Séror et al., J Exp Med. 2011

 

Crosstalk between lethal, stress-adaptive and metabolic pathways in aging and disease. We provided an operational definition of "mitotic catastrophe" as an oncosuppressive mechanism, launched the debate that necrosis may be a regulated cell death event, and showed that autophagy usually is a cytoprotective event that avoids cell death and actually prolongs longevity when it is induced at the whole-organism level. We deciphered part of the molecular crosstalk between apoptosis and autophagy, showing that proteins with BH3 domains can control both catabolic events and that activation of prominent elements of the classical NFB activation pathway (in particular TAK1 and the proteins of the IKK complex) are required for the optimal induction of autophagy. We discovered that the pro-apoptotic tumor suppressor protein p53 plays a dual role in the control of autophagy, namely as an autophagy-inducing transcription factor and as an autophagy-repressing cytoplasmic factor. We also found that STAT3 can inhibit autophagy via the inhibition of PKR. We identified spermidine as a novel, non-toxic inducer of autophagy and determined its mode of action as a life span-extending drug in yeast, nematodes, flies and mice. We accumulated extensive evidence that acetyl-coenzyme A and protein acetylation repress autophagy and that “caloric restriction mimetics” including spermidine induce autophagy via deacetylation reactions. We launched the (still valid) hypothesis that all longevity extending manipulations, be they metabolic, pharmacological or genetic, must induce autophagy to be efficient. We have also shown that spermidine supplementation reduces cardiac morbidity and mortality in rodents and humans via the induction of autophagy.

Dedicated Editorial Comments: Autophagy. 2012; Cell. 2007; Cell Cycle. 2008; Cell Cycle. 2009;  Cell Cycle. 2009;  Cell Cycle. 2009; Cell Cycle 2010;  Cell Cycle. 2010; Cell Cycle. 2012; Cell Cycle. 2012; Cell Cycle. 2013; Cell Cycle. 2013; Cell Death & Dis. 2010), Cell Metabo.. 2014, Chem. Biol. 2014, EMBO J. 2015; Faculty of 1000 (http://www.facultyof1000.com), JAK/STAT. 2013; Nat. Cell Biol. 2008; Nat. Cell Biol.  2009, Nat. Med. 2016; Nat. Immunol. 2012; Nat. Rev. Mol. Cell Biol. 2009; Nat. Rev. Mol. Cell Biol. 2012, Oncogene. 2010;, Nat. Rev. Cardio. (in press), Nat. Rev. Clin. Oncol. 2014), Nat. Rev Drug Discov. (in press), Nat. Rev. Endocri. (in press), Rejuv Res. 2013; SciBX. 2008;  SciBX..2011; Sci. Signall. 2013. Principal references: Ferri and Kroemer. Nat Cell Biol. 2001; Boya et al., J Exp Med. 2003; Boya P, et al., Mol Cell Biol. 2005; Kroemer and Martin. Nat. Med. 2005; Castedo et al., EMBO J. 2006; Maiuri et al., EMBO J. 2007; Zermati et al., Mol Cell. 2007; Levine and Kroemer. Cell 2008; Tasdemir et al., Nat Cell Biol. 2008; Green and Kroemer. Nature 2009; Eisenberg et al., Nat Cell Biol. 2009; Criollo et al., EMBO J. 2010; Vitale et al., EMBO J. 2010; Kroemer et al., Mol Cell. 2010; Morselli et al., J Cell Biol. 2011; Rubinsztein et al., Cell 2011; Criollo et al., EMBO J. 2011; Shen et al., Mol Cell 2012; López-Otín et al., Cell. 2013; Lissa et al., Proc Natl Acad Sci USA. 2014; Eisenberg et al., Cell Metab. 2014; Mariño et al., Mol Cell. 2014; Galluzzi et al., Cell. 2014; Galluzzi et al., EMBO J. 2015; Niso-Santano, et al., EMBO J. 2015; Pietrocola et al., Cell Metab. 2015; Sica et al., Mol Cell. 2015;nGalluzzi et al., Cell. 2016; Eisenberg et al., Nat Med. 2016

 

Immunogenic cell death for optimal anticancer chemotherapy. Our group invalidated the dogma that apoptosis is a non-immunogenic cell death modality. We demonstrated that, depending on the upstream triggers, apoptosis can be immunogenic and hence alert the innate immune system and instruct it to stimulate a cognate response against dead-cell antigens. This has opened a new field of research at the frontier between immunology and cell biology, allowing us to define the molecular properties of immunogenic cell death (ICD). We found that ICD is characterized by autocrine stimulation of type 1 interferon (IFN) receptors, the pre-apoptotic exposure of calreticulin (CRT) on the cell surface, release of ATP during the blebbing phase of apoptosis, and post-apoptotic exodus of annexin A1 (ANXA1) and the chromatin-binding protein high mobility group B1 (HMGB1). Type 1 interferon secretion depends on the stimulation of TLR3, CRT exposure on an endoplasmic reticulum stress response, ATP release on pre-mortem autophagy, and annexin A1/HMGB1 exodus on secondary necrosis. CRT, ATP, ANXA1 and HMGB1 interact with four receptors (CD91 receptor, purinergic P2Y2 or P2X7 receptors, formyl peptide receptor-1 [FPR1], and toll-like receptor 4 [TLR4], respectively) that are present on the surface of dendritic cells or their precursors. CD91, P2Y2, FPR1, P2RX7 and TLR4 promote engulfment of dying cells, attraction of dendritic cells, juxtaposition of dendritic and dying cells, production of interleukin-1β and presentation of tumor antigens, respectively. Local induction of endoplasmic reticulum stress in the tumor bed and systemic induction of autophagy increase anticancer immune responses. We have launched and then proven the hypothesis that the immune response against dying tumor cells dictates the therapeutic success of anticancer chemotherapy, both in mouse models and in cancer patients. Obviously, this discovery has had major consequences for the comprehension, conception and implementation of anticancer chemotherapies. Indeed, we postulate that, at least in certain cases, both classical and targeted anticancer therapies require an active contribution of the immune system to be optimally efficient. We obtained clinical evidence that this hypothesis holds true for anthracycline-treated breast cancer, oxaliplatin-treated colorectal cancer, and imatinib-treated gastrointestinal stromal tumors, among others.

Dedicated Editorial Comments: Apoptosis. 2007; Cancer Cell. 2007; Cancer Cell. 2015; Cancer Cell. 2016; Cancer Discov. 2012; Cancer Discov. 2012; Cancer Discov. 2013; Cancer Discov. 2014; Cancer Discov. 2015; Cell Cycle 2013;, Faculty of 1000 (http://www.facultyof1000.com), Immunity 2013; Nat. Immunol. 2007; J. Nat. Cancer Inst. Mongr. 2010, Nat. Biotechnol. 2007;  Nat. Med. 2007; Nat. Med. 2014; Nat Rev. Cancer. 2007; Nat Rev. Cancer. 2014; Nat Rev. Cancer. 2016, Nat. Rev. Immunol. 2012; Nat. Rev. Immunol. 2014; N. Engl. J. Med. 2006; N. Engl. J. Med. 2006 N. Engl. J. Med. 2012; OncoImmunology. 2014; Science. 2011; Science. 2012; Science. 2015; Science. 2015; ScBX. 2011; SciBX. 2011; SciBX. 2012; SciBX. 2012Principal references: Casares et al., J Exp Med. 2005; Taieb et al., Nat Med. 2006; Obeid et al., Nat Med. 2007; Apetoh et al., Nat Med. 2007; Zitvogel et al., J Clin Invest. 2008; Panaretakis et al., EMBO J. 2009; Ghiringhelli et al., Nat Med. 2009; Zitvogel et al., Cell. 2010; Ma et al., J Exp Med. 2011; Michaud et al., Science. 2011; Zitvogel et al., Nat Immunol. 2012; Senovilla et al., Science. 2012; Ma et al., Immunity. 2013; Zitvogel et al., Immunity. 2013; Ma et al., Immunity. 2013; Rao et al., Nat Commun. 2014; Sistigu et al., Nat Med. 2014; Kroemer et al., Nat Med. 2015; Vacchelli et al., Science. 2015; Galluzzi et al., Cancer Cell. 2015; Zitvogel et al., Cell. 2016; Pitt et al., Immunity. 2016; Pietrocola et al., Cancer Cell 2016

 

Clinical research: patient-relevant biomarkers and successful clinical trials Our group has identified biological parameters that predict clinical outcome in patients with multiple carcinomas (such as co-treatment with cardiac glycosides), non-small cell lung cancer (PDXK expression by malignant cells, activity of poly [ADP-ribose] polymerase), gastrointestinal stromal tumor and pediatric neuroblastoma (expression of NKp30 isoforms by circulating NK cells), breast cancer (autophagy and HMGB1 expression), as well as in patients with melanomas treated with ipiluminab (soluble CD25 in the plasma). We advocated the off-target use of the EGFR inhibitor erlotinib in acute myeloid leukemia and then performed a phase 1/2 trial with a 20% success rate. We also developed a treatment of cystic fibrosis based on the activation of autophagy (with cysteamine plus EGCG), resulting in Phase 1 and 2 trials that improved the sweat test in 90% of patients with the F508del CFTR mutation.

Dedicated Editorial Comments: Faculty of 1000 (http://www.facultyof1000.com); Nat. Rev. Cancer. 2011; SciBX. 2011. Principal references: Olaussen et al., N Engl J Med. 2007; Boehrer et al., Blood. 2008; Delahaye et al., Nat Med. 2011; Galluzzi et al., Cell Rep. 2012; Menger et al., Sci Transl Med. 2012; Thepot et al., Leuk Res. 2014; Stefano et al., Autophagy. 2014; Hannani et al., Cell Res. 2015; Semeraro et al., Sci Transl Med. 2015; Michels et al., Ann Oncol. 2015; Ladoire et al., Autophagy. 2015; Ladoire et al., Autophagy. 2016; Tosco et al., Cell Death Differ. 2016

 

Reviews and position papers in Annual Reviews and Nature Reviews To foster the in-depth comprehension of cellular stress and death in health and disease, we have written some 30 articles that analyze, synthesize and conceptualize the state-of-the-art of the research area for Nature Reviews or Annual Reviews.

Principal references: Kroemer et al., Annu Rev Physiol. 1998; Zamzami and Kroemer. Nat Rev Mol Cell Biol. 2001; Zhivotovsky and Kroemer. Nat Rev Mol Cell Biol. 2004; Kroemer and Jäättelä. Nat Rev Cancer. 2005; Faivre et al., Nat Rev Drug Discov. 2006; Zitvogel et al., Nat Rev Immunol. 2006; Maiuri et al., Nat Rev Mol Cell Biol. 2007 Zitvogel et al., Nat Rev Immunol. 2008; Kroemer and Levine. Nat Rev Mol Cell Biol. 2008; Green et al., Nat Rev Immunol. 2009; Galluzzi et al., Nat Rev Neurosci. 2009; Fulda et al., Nat Rev Drug Discov. 2010; Vandenabeele et al., Nat Rev Mol Cell Biol. 2010; Kepp et al., Nat Rev Drug Discov. 2011; Zitvogel et al., Nat Rev Clin Oncol. 2011 Vitale et al., Nat Rev Mol Cell Biol. 2011; Galluzzi et al., Nat Rev Drug Discov. 2012; Galluzzi et al., Nat Rev Mol Cell Biol. 2012 Kroemer et al., Annu Rev Immunol 2013 Galluzzi et al., Nat Rev Drug Discov. 2013; Marino et al., Nat Rev Mol Cell Biol. 2014; Madeo et al., Nat Rev Drug Discov. 2014; Zitvogel et al., Nat Rev Immunol. 2015 Zitvogel et al., Nat Rev Clin Oncol. 2016 Galluzzi et al., Nat Rev Neurosci. 2016; Zitvogel et al., Nat Rev Cancer. 2016 Galluzzi et al., Nat Rev Immunol. 2016; Galluzzi et al., Nat Rev Clin Oncol. In press; Galluzzi et al., Annual Review of Pathology: Mechanisms of Disease. 2016; Galluzzi et al., Nat Rev Drug Discov. In press

 


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among others