The receptor NLRP3 is involved in the formation of the NLRP3 inflammasome that activates caspase-1 and mediates the release of interleukin 1β (IL-1β) and IL-18. Whether NLRP3 can shape immunological ...function independently of inflammasomes is unclear. We found that NLRP3 expression in CD4(+) T cells specifically supported a T helper type 2 (TH2) transcriptional program in a cell-intrinsic manner. NLRP3, but not the inflammasome adaptor ASC or caspase-1, positively regulated a TH2 program. In TH2 cells, NLRP3 bound the Il4 promoter and transactivated it in conjunction with the transcription factor IRF4. Nlrp3-deficient TH2 cells supported melanoma tumor growth in an IL-4-dependent manner and also promoted asthma-like symptoms. Our results demonstrate the ability of NLRP3 to act as a key transcription factor in TH2 differentiation.
Chemotherapeutic agents are widely used for cancer treatment. In addition to their direct cytotoxic effects, these agents harness the host's immune system, which contributes to their antitumor ...activity. Here we show that two clinically used chemotherapeutic agents, gemcitabine (Gem) and 5-fluorouracil (5FU), activate the NOD-like receptor family, pyrin domain containing-3 protein (Nlrp3)-dependent caspase-1 activation complex (termed the inflammasome) in myeloid-derived suppressor cells (MDSCs), leading to production of interleukin-1β (IL-1β), which curtails anticancer immunity. Chemotherapy-triggered IL-1β secretion relied on lysosomal permeabilization and the release of cathepsin B, which bound to Nlrp3 and drove caspase-1 activation. MDSC-derived IL-1β induced secretion of IL-17 by CD4(+) T cells, which blunted the anticancer efficacy of the chemotherapy. Accordingly, Gem and 5FU exerted higher antitumor effects when tumors were established in Nlrp3(-/-) or Casp1(-/-) mice or wild-type mice treated with interleukin-1 receptor antagonist (IL-1Ra). Altogether, these results identify how activation of the Nlrp3 inflammasome in MDSCs by 5FU and Gem limits the antitumor efficacy of these chemotherapeutic agents.
Tumors poorly infiltrated by T cells are more resistant to immunogenic chemotherapies and checkpoint inhibition than highly infiltrated tumors. Using murine models, we found that CCR6
type 3 innate ...lymphoid cells (ILC3s) can trigger an increase in the number of T cells infiltrating a tumor. Shortly after administration of cisplatin chemotherapy, production of the chemokine CCL20 and proinflammatory cytokine IL-1β at the tumor site led to the recruitment and activation of ILC3s. Within the tumor, ILC3 production of the chemokine CXCL10 was responsible for the recruitment of CD4
and CD8
T lymphocytes to the tumor. ILC3-dependent infiltration of T cells was essential for antitumor immune responses and increased the efficacy of checkpoint inhibition. Thus, we reveal an essential role of CCL20 and IL-1β, which promote ILC3-dependent antitumor immunity and enhance tumor sensitivity to immunotherapy.
Although Th17 cells are known to promote tissue inflammation and autoimmunity, their role during cancer progression remains elusive. Here, we showed that in vitro Th17 cells generated with the ...cytokines IL-6 and TGF-β expressed CD39 and CD73 ectonucleotidases, leading to adenosine release and the subsequent suppression of CD4+ and CD8+ T cell effector functions. The IL-6-mediated activation of the transcription factor Stat3 and the TGF-β-driven downregulation of Gfi-1 transcription factor were both essential for the expression of ectonucleotidases during Th17 cell differentiation. Stat3 supported whereas Gfi-1 repressed CD39 and CD73 expression by binding to their promoters. Accordingly, Th17 cells differentiated with IL-1β, IL-6, and IL-23 but without TGF-β did not express ectonucleotidases and were not immunosuppressive. Finally, adoptive transfer of Th17 cells induced by TGF-β and IL-6 promoted tumor growth in a CD39-dependent manner. Thus, ectonucleotidase expression supports the immunosuppressive fate of Th17 cells in cancer.
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► Th17 cells express CD39 and CD73 ectonucleotidases ► Ectonucleotidase expression is transcriptionally regulated by STAT3 and GFI-1 ► Ectonucleotidase expression determines inflammatory vs suppressive fate of Th17 cells
Background: Chemotherapy is currently evaluated in order to enhance the efficacy of immune checkpoint blockade (ICB) therapy in colorectal cancer. However, the mechanisms by which these drugs could ...synergize with ICB remains unclear. The impact of chemotherapy on the PD-1/PD-L1 pathway and the resulting anticancer immune responses was assessed in two mouse models of colorectal cancer and validated in tumor samples from metastatic colorectal cancer patients that received neoadjuvant treatment. We demonstrated that 5-Fluorouracil plus Oxaliplatin (Folfox) drove complete tumor cure in mice when combined to anti-PD-1 treatment, while each monotherapy failed. This synergistic effect relies on the ability of Folfox to induce tumor infiltration by activated PD-1
+
CD8 T cells in a T-bet dependent manner. This effect was concomitantly associated to the expression of PD-L1 on tumor cells driven by IFN-γ secreted by PD-1+ CD8 T cells, indicating that Folfox triggers tumor adaptive immune resistance. Finally, we observed an induction of PD-L1 expression and high CD8 T cell infiltration in the tumor microenvironment of colorectal cancer patients treated by Folfox regimen. Our study delineates a molecular pathway involved in Folfox-induced adaptive immune resistance in colorectal cancer. The results strongly support the use of immune checkpoint blockade therapy in combination with chemotherapies like Folfox.
It is known that differentiation of Th17 cells is promoted by activation of STAT3 and inhibited by activation of STAT1. Although both transcription factors are activated by several cytokines, ...including IL-6, IL-21, and IL-27, each of these cytokines has a very different effect on Th17 differentiation, ranging from strong induction (IL-6) to strong inhibition (IL-27). To determine the molecular basis for these differences, we measured STAT3 and STAT1 activation profiles for IL-6, IL-21, and IL-27, as well as for cytokine pairs over time. We found that the ratio of activated STAT3/activated STAT1 is crucial in determining whether cytokines promote or inhibit Th17 differentiation. IL-6 and IL-21 induced p-STAT3/p-STAT1 ratios > 1, leading to the promotion of Th17 differentiation, whereas IL-27 or IL-6+IL-27 induced p-STAT3/p-STAT1 ratios < 1, resulting in inhibition of Th17 differentiation. Consistent with these findings, we show that IL-27 induces sufficient p-STAT3 to promote Th17 differentiation in the absence of STAT1. Furthermore, IL-27-induced STAT1-deficient T cells were indistinguishable from bona fide highly proinflammatory Th17 cells because they induced severe experimental autoimmune encephalomyelitis upon adoptive transfer. Our results suggest that the ratio of p-STAT3/p-STAT1 induced by a cytokine or cytokine pairs can be used to predict whether they induce a competent Th17-differentiation program.
The mechanisms leading to NOD-leucine rich repeat and pyrin containing protein 3 (NLRP3) inflammasome activation are still debated. It is well established that oligomerized NLRP3 interacts with ...apoptosis associated Speck-like protein containing a CARD domain (ASC) which polymerizes into filaments recruiting procaspase-1, leading to its activation. However, pathways triggering NLRP3 activation, such as potassium efflux, ROS production or lysosomal permeabilization, can be required or not, depending on the activators used. Here we proposed to evaluate the importance of Cathepsin B on NLRP3 inflammasome assembly and activation. Using Cathepsin B
BMDMs (Bone Marrow-Derived Macrophages), we first show that Cathepsin B is required for caspase-1 activation, IL-1β production and ASC speck formation, upon treatment with different types of NLRP3 activators, i.e., ATP, nigericin or crystals. Moreover, in these conditions, Cathepsin B interacts with NLRP3 at the endoplasmic reticulum (ER) level. To conclude, different NLRP3 activators lead to Cathepsin B interaction with NLRP3 at the ER level and to subsequent caspase-1 activation.
BackgroundT follicular helper cells (Tfh) are essential to shape B cell response during germinal center formation. Tfh accumulation has been reported in various human cancers, with positive or ...negative prognostic roles. However, the mechanisms explaining the accumulation of Tfh and their role in cancer remain obscure.MethodsIn vitro differentiated and mouse cell sorted Tfh phenotype was evaluated by flow cytometry and quantitative PCR (qPCR). Antitumor effect of Tfh was evaluated by adoptive transfer in different tumor-bearing mice models. The involvement of immune cells, cytokines and chemokines was evaluated, using depleting antibodies. Chemokines and cytokines expression and production were evaluated by qPCR and ELISA. In human, the impact of immune cells and chemokines on survival was evaluated by analyzing transcriptomic data from public databases and from our own patient cohorts.ResultsIn this study, we show that Tfh exert an antitumor immune effect in a CD8+-dependent manner. Tfh produce interleukin-21, which sustains proliferation, viability, cytokine production and cytotoxic functions of exhausted T cells. The presence of Tfh is required for efficacy of antiprogrammed cell death ligand-1 therapy. Tfh accumulate in the tumor bed and draining lymph nodes in different mouse cancer models. This recruitment is due to the capacity of transforming growth factor β to drive Chemokine (C-X-C motif) Ligand 13 expression, a chemoattractant of Tfh, by intratumor CD8+ T cells. Accumulation of Tfh and exhausted CD8+ T cells predicts cancer outcome in various cancer types. In patients treated with anti-programmed cell death-1 mAb, accumulation of Tfh and CD8+ at the tumor site is associated with outcome.ConclusionThis study provides evidence that CD8+/Tfh crosstalk is important in shaping antitumor immune response generated by immunotherapy.
Interferon regulatory factors (IRF) have critical functions in lymphoid development and in immune response regulation. Although many studies have described the function of IRF4 in CD4
T cells, few ...have focused on the IRF4 homologue, IRF8. Here, we show that IRF8 is required for Th9 differentiation in vitro and in vivo. IRF8 functions through a transcription factor complex consisting of IRF8, IRF4, PU.1 and BATF, which binds to DNA and boosts Il9 transcription. By contrast, IRF8 deficiency promotes the expression of other genes such as Il4, as IRF8 dimerises with the transcriptional repressor ETV6 and inhibits Il4 expression. In vivo, IRF8 is essential for the anti-tumour effects of Th9 cells in mouse melanoma models. Our results show that IRF8 complexes boost the Th9 program and repress Il4 expression to modulate Th9 cell differentiation, thereby implicating IRF8 as a potential therapeutic target to affect Th9 responses in cancer therapy.
Bleomycin (BLM) is an anticancer drug currently used for the treatment of testis cancer and Hodgkin lymphoma. This drug triggers cancer cell death via its capacity to generate radical oxygen species ...(ROS). However, the putative contribution of anticancer immune responses to the efficacy of BLM has not been evaluated. We make here the observation that BLM induces immunogenic cell death. In particular, BLM is able to induce ROS-mediated reticulum stress and autophagy, which result in the surface exposure of chaperones, including calreticulin and ERp57, and liberation of HMBG1 and ATP. BLM induces anti-tumor immunity which relies on calreticulin, CD8(+) T cells and interferon-γ. We also find that, in addition to its capacity to trigger immunogenic cell death, BLM induces expansion of Foxp3+ regulatory T (Treg) cells via its capacity to induce transforming growth factor beta (TGFβ) secretion by tumor cells. Accordingly, Treg cells or TGFβ depletion dramatically potentiates the antitumor effect of BLM. We conclude that BLM induces both anti-tumor CD8(+) T cell response and a counteracting Treg proliferation. In the future, TGFβ or Treg inhibition during BLM treatment could greatly enhance BLM anti-tumor efficacy.
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