👤 Zitvogel, Laurence

For decades, great strides have been made in the field of immunometabolism. A plethora of evidence ranging from basic mechanisms to clinical transformation has gradually embarked on immunometabolism to the center stage of innate and adaptive immunomodulation. Given this, we focus on changes in immunometabolism, a converging series of biochemical events that alters immune cell function, propose the immune roles played by diversified metabolic derivatives and enzymes, emphasize the key metabolism-related checkpoints in distinct immune cell types, and discuss the ongoing and upcoming realities of clinical treatment. It is expected that future research will reduce the current limitations of immunotherapy and provide a positive hand in immune responses to exert a broader therapeutic role. Show less

In response to some chemotherapeutic agents such as anthracyclines and oxaliplatin, cancer cells undergo immunogenic apoptosis, meaning that their corpses are engulfed by dendritic cells and that tumor cell antigens are presented to tumor-specific CD8(+) T cells, which then control residual tumor cells. One of the peculiarities of immunogenic apoptosis is the early cell surface exposure of calreticulin (CRT), a protein that usually resides in the lumen of the endoplasmic reticulum (ER). When elicited by anthracyclines or oxaliplatin, the CRT exposure pathway is activated by pre-apoptotic ER stress and the phosphorylation of the eukaryotic translation initiation factor eIF2alpha by the kinase PERK, followed by caspase-8-mediated proteolysis of the ER-sessile protein BAP31, activation of the pro-apoptotic proteins Bax and Bak, anterograde transport of CRT from the ER to the Golgi apparatus and exocytosis of CRT-containing vesicles, finally resulting in CRT translocation onto the plasma membrane surface. Interruption of this complex pathway abolishes CRT exposure, annihilates the immunogenicity of apoptosis, and reduces the immune response elicited by anticancer chemotherapies. We speculate that human cancers that are incapable of activating the CRT exposure pathway are refractory to the immune-mediated component of anticancer therapies. Show less

Both the pre-apoptotic exposure of calreticulin (CRT) and the post-apoptotic release of high-mobility group box 1 protein (HMGB1) are required for immunogenic cell death elicited by anthracyclins. Here, we show that both oxaliplatin (OXP) and cisplatin (CDDP) were equally efficient in triggering HMGB1 release. However, OXP, but not CDDP, stimulates pre-apoptotic CRT exposure in a series of murine and human colon cancer cell lines. Subcutaneous injection of OXP-treated colorectal cancer (CRC), CT26, cells induced an anticancer immune response that was reduced by short interfering RNA-mediated depletion of CRT or HMGB1. In contrast, CDDP-treated CT26 cells failed to induce anticancer immunity, unless recombinant CRT protein was absorbed into the cells. CT26 tumors implanted in immunocompetent mice responded to OXP treatment in vivo, and this therapeutic response was lost when CRT exposure by CT26 cells was inhibited or when CT26 cells were implanted in immunodeficient mice. The knockout of toll-like receptor 4 (TLR4), the receptor for HMGB1, also resulted in a deficient immune response against OXP-treated CT26 cells. In patients with advanced (stage IV, Duke D) CRC, who received an OXP-based chemotherapeutic regimen, the loss-of-function allele of TLR4 (Asp299Gly in linkage disequilibrium with Thr399Ile, reducing its affinity for HMGB1) was as prevalent as in the general population. However, patients carrying the TLR4 loss-of-function allele exhibited reduced progression-free and overall survival, as compared with patients carrying the normal TLR4 allele. In conclusion, OXP induces immunogenic death of CRC cells, and this effect determines its therapeutic efficacy in CRC patients. Show less

Dying tumour cells can elicit a potent anticancer immune response by exposing the calreticulin (CRT)/ERp57 complex on the cell surface before the cells manifest any signs of apoptosis. Here, we enumerate elements of the pathway that mediates pre-apoptotic CRT/ERp57 exposure in response to several immunogenic anticancer agents. Early activation of the endoplasmic reticulum (ER)-sessile kinase PERK leads to phosphorylation of the translation initiation factor eIF2alpha, followed by partial activation of caspase-8 (but not caspase-3), caspase-8-mediated cleavage of the ER protein BAP31 and conformational activation of Bax and Bak. Finally, a pool of CRT that has transited the Golgi apparatus is secreted by SNARE-dependent exocytosis. Knock-in mutation of eIF2alpha (to make it non-phosphorylatable) or BAP31 (to render it uncleavable), depletion of PERK, caspase-8, BAP31, Bax, Bak or SNAREs abolished CRT/ERp57 exposure induced by anthracyclines, oxaliplatin and ultraviolet C light. Depletion of PERK, caspase-8 or SNAREs had no effect on cell death induced by anthracyclines, yet abolished the immunogenicity of cell death, which could be restored by absorbing recombinant CRT to the cell surface. Show less