Integrin αvβ8-mediated TGF-β activation by effector regulatory T sells is essential for suppression of T-Cell-mediated inflammation

Regulatory T (Treg) cells play a pivotal role in suppressing self-harmful T cell responses, but how Treg cells mediate suppression to maintain immune homeostasis and limit responses during inflammation is unclear. Here we show that effector Treg cells express high amounts of the integrin αvβ8, which enables them to activate latent transforming growth factor-β (TGF-β). Treg-cell-specific deletion of integrin αvβ8 did not result in a spontaneous inflammatory phenotype, suggesting that this pathway is not important in Treg-cell-mediated maintenance of immune homeostasis. However, Treg cells lacking expression of integrin αvβ8 were unable to suppress pathogenic T cell responses during active inflammation. Thus, our results identify a mechanism by which Treg cells suppress exuberant immune responses, highlighting a key role for effector Treg-cell-mediated activation of latent TGF-β in suppression of self-harmful T cell responses during active inflammation

Role of TGF-beta within ILC3 and T cells in spontaneous microbiota-induced colorectal cancer development

Le côlon des mammifères est colonisé d'environ 1013 bactéries. Si ce microbiote contribue au métabolisme, au développement et à la protection de l'organisme et représente une source massive d'antigènes. Il doit donc être compartimenté afin d'empêcher leur dissémination dans l'organisme où il pourrait être délétère. Lors de ma thèse, je me suis intéressé au rôle du Transforming Growth Factor beta (TGF-bêta, une cytokine fortement exprimée sous forme inactive au niveau de l'intestin des mammifères. Nous avons pu montrer que l'expression de l'intégrine alphav bêta 8par les lymphocytes T régulateurs (Treg) est essentielle à l'activation du TGF-bêta. Par ailleurs, mes travaux démontrent que deux protéines de la voie de signalisation du TGF-bêta, TIF-1gamma et SMAD4, contrôlent l'expression de l'IL-22 dans les cellules lymphocytaires innées de groupe 3 (ILC3) du côlon, responsable du maintien l'intégrité de la barrière intestinale empêchant l'entrée massive de bactéries et une suractivation des lymphocytes Th17 impliqués dans le développement spontané de cancers colorectaux. Ainsi, mes travaux de recherche ont permis de mettre en évidence le rôle clé du TGF-bêta dans le maintien de l'intégrité intestinale essentiel à la prévention du développement de cancers colorectaux induits spontanément par le microbioteMammalian colon harbors about 1013 bacteria. Although this microbiota contributes to metabolism, development and protection of the organism, it constitutes a huge source of antigens and must be compartmentalized in order to prevent intestinal bacteria dissemination in the organism that could be harmful for the host. During my PhD, I was interested in the role of Transforming Growth Factor beta (TGF-beta, a highly expressed cytokine and produced as an inactive form in mammalian gut. We showed that the expression of integrin alpha v beta 8by regulatory T cells (Treg) is essential to activate TGF-beta. Moreover, my work revealed that two proteins of the TGF-beta signaling pathway, TIF-1gamma and SMAD4, are responsible for the control of the expression of IL-22 within colonic group 3 Innate Lymphoid Cells (ILC3) which maintains the intestinal barrier integrity and prevents bacteria from entering and over-activation of Th17 cells involved in spontaneous colorectal cancer development. My work revealed a key role for TGF-beta in the maintenance of intestinal barrier-integrity essential to prevent spontaneous microbiota-induced colorectal cancer developmen

IL-23 and IL-2 activation of STAT5 is required for optimal IL-22 production in ILC3s during colitis

Signal transducer and activator of transcription (STAT) proteins have critical roles in the development and function of immune cells. STAT signaling is often dysregulated in patients with inflammatory bowel disease (IBD), suggesting the importance of STAT regulation during the disease process. Moreover, genetic alterations in and (e.g., deletions, mutations, and single-nucleotide polymorphisms) are associated with an increased risk for IBD. In this study, we elucidated the precise roles of STAT5 signaling in group 3 innate lymphoid cells (ILC3s), a key subset of immune cells involved in the maintenance of gut barrier integrity. We show that mice lacking either STAT5a or STAT5b are more susceptible to -mediated colitis and that interleukin-2 (IL-2)- and IL-23-induced STAT5 drives IL-22 production in both mouse and human colonic lamina propria ILC3s. Mechanistically, IL-23 induces a STAT3-STAT5 complex that binds IL-22 promoter DNA elements in ILC3s. Our data suggest that STAT5a/b signaling in ILC3s maintains gut epithelial integrity during pathogen-induced intestinal disease

Antitumor efficacy of combined CTLA4/PD-1 blockade without intestinal inflammation is achieved by elimination of FcγR interactions

Background Programmed cell death protein 1 (PD-1) and CTLA4 combination blockade enhances clinical efficacy in melanoma compared with targeting either checkpoint alone; however, clinical response improvement is coupled with increased risk of developing immune-related adverse events (irAE). Delineating the mechanisms of checkpoint blockade-mediated irAE has been hampered by the lack of animal models that replicate these clinical events.Methods We have developed a mouse model of checkpoint blockade-mediated enterocolitis via prolonged administration of an Fc-competent anti-CTLA4 antibody.Results Sustained treatment with Fc-effector, but not Fc-mutant or Fc-null, anti-CTLA4 antagonist for 7 weeks resulted in enterocolitis. Moreover, combining Fc-null or Fc-mutant CTLA4 antagonists with PD-1 blockade results in potent antitumor combination efficacy indicating that Fc-effector function is not required for combination benefit.Conclusion These data suggest that using CTLA4 antagonists with no Fc-effector function can mitigate gut inflammation associated with anti-CTLA4 antibody therapy yet retain potent antitumor activity in combination with PD-1 blockade

Table_1_SPATA2 and CYLD inhibit T cell infiltration into colorectal cancer via regulation of IFN-γ/STAT1 axis.xlsx

IntroductionColorectal cancer (CRC) is largely refractory to currently available immunotherapies such as blockade of programmed cell death protein-1 (PD-1).ResultsIn this study, we identified SPATA2 and its protein partner CYLD as novel regulators of CXC-ligand 10 (CXCL10), a T-cell-attractant chemokine, in CRC. By specifically deleting SPATA2 and CYLD in human and mouse CRC cell lines, we showed that these two proteins inhibit STAT1 accumulation and activation and subsequently CXCL10 expression in tumor cells. At steady-state, STAT1 is highly ubiquitinated in a SPATA2/CYLD-dependent manner. Finally, we demonstrated that tumor-specific deletion of SPATA2 and CYLD enhances anti-PD-1 response in vivo.DiscussionOur data suggest that SPATA2 and CYLD represent two potential novel targets for treatment of immune-excluded, PD-1-resistant tumors.</p

Image_2_SPATA2 and CYLD inhibit T cell infiltration into colorectal cancer via regulation of IFN-γ/STAT1 axis.jpeg

IntroductionColorectal cancer (CRC) is largely refractory to currently available immunotherapies such as blockade of programmed cell death protein-1 (PD-1).ResultsIn this study, we identified SPATA2 and its protein partner CYLD as novel regulators of CXC-ligand 10 (CXCL10), a T-cell-attractant chemokine, in CRC. By specifically deleting SPATA2 and CYLD in human and mouse CRC cell lines, we showed that these two proteins inhibit STAT1 accumulation and activation and subsequently CXCL10 expression in tumor cells. At steady-state, STAT1 is highly ubiquitinated in a SPATA2/CYLD-dependent manner. Finally, we demonstrated that tumor-specific deletion of SPATA2 and CYLD enhances anti-PD-1 response in vivo.DiscussionOur data suggest that SPATA2 and CYLD represent two potential novel targets for treatment of immune-excluded, PD-1-resistant tumors.</p

Image_5_SPATA2 and CYLD inhibit T cell infiltration into colorectal cancer via regulation of IFN-γ/STAT1 axis.jpeg

IntroductionColorectal cancer (CRC) is largely refractory to currently available immunotherapies such as blockade of programmed cell death protein-1 (PD-1).ResultsIn this study, we identified SPATA2 and its protein partner CYLD as novel regulators of CXC-ligand 10 (CXCL10), a T-cell-attractant chemokine, in CRC. By specifically deleting SPATA2 and CYLD in human and mouse CRC cell lines, we showed that these two proteins inhibit STAT1 accumulation and activation and subsequently CXCL10 expression in tumor cells. At steady-state, STAT1 is highly ubiquitinated in a SPATA2/CYLD-dependent manner. Finally, we demonstrated that tumor-specific deletion of SPATA2 and CYLD enhances anti-PD-1 response in vivo.DiscussionOur data suggest that SPATA2 and CYLD represent two potential novel targets for treatment of immune-excluded, PD-1-resistant tumors.</p

Image_4_SPATA2 and CYLD inhibit T cell infiltration into colorectal cancer via regulation of IFN-γ/STAT1 axis.jpeg

IntroductionColorectal cancer (CRC) is largely refractory to currently available immunotherapies such as blockade of programmed cell death protein-1 (PD-1).ResultsIn this study, we identified SPATA2 and its protein partner CYLD as novel regulators of CXC-ligand 10 (CXCL10), a T-cell-attractant chemokine, in CRC. By specifically deleting SPATA2 and CYLD in human and mouse CRC cell lines, we showed that these two proteins inhibit STAT1 accumulation and activation and subsequently CXCL10 expression in tumor cells. At steady-state, STAT1 is highly ubiquitinated in a SPATA2/CYLD-dependent manner. Finally, we demonstrated that tumor-specific deletion of SPATA2 and CYLD enhances anti-PD-1 response in vivo.DiscussionOur data suggest that SPATA2 and CYLD represent two potential novel targets for treatment of immune-excluded, PD-1-resistant tumors.</p

Image_3_SPATA2 and CYLD inhibit T cell infiltration into colorectal cancer via regulation of IFN-γ/STAT1 axis.jpeg

IntroductionColorectal cancer (CRC) is largely refractory to currently available immunotherapies such as blockade of programmed cell death protein-1 (PD-1).ResultsIn this study, we identified SPATA2 and its protein partner CYLD as novel regulators of CXC-ligand 10 (CXCL10), a T-cell-attractant chemokine, in CRC. By specifically deleting SPATA2 and CYLD in human and mouse CRC cell lines, we showed that these two proteins inhibit STAT1 accumulation and activation and subsequently CXCL10 expression in tumor cells. At steady-state, STAT1 is highly ubiquitinated in a SPATA2/CYLD-dependent manner. Finally, we demonstrated that tumor-specific deletion of SPATA2 and CYLD enhances anti-PD-1 response in vivo.DiscussionOur data suggest that SPATA2 and CYLD represent two potential novel targets for treatment of immune-excluded, PD-1-resistant tumors.</p

Image_1_SPATA2 and CYLD inhibit T cell infiltration into colorectal cancer via regulation of IFN-γ/STAT1 axis.jpg

IntroductionColorectal cancer (CRC) is largely refractory to currently available immunotherapies such as blockade of programmed cell death protein-1 (PD-1).ResultsIn this study, we identified SPATA2 and its protein partner CYLD as novel regulators of CXC-ligand 10 (CXCL10), a T-cell-attractant chemokine, in CRC. By specifically deleting SPATA2 and CYLD in human and mouse CRC cell lines, we showed that these two proteins inhibit STAT1 accumulation and activation and subsequently CXCL10 expression in tumor cells. At steady-state, STAT1 is highly ubiquitinated in a SPATA2/CYLD-dependent manner. Finally, we demonstrated that tumor-specific deletion of SPATA2 and CYLD enhances anti-PD-1 response in vivo.DiscussionOur data suggest that SPATA2 and CYLD represent two potential novel targets for treatment of immune-excluded, PD-1-resistant tumors.</p