TGFβ prevents IgE-mediated allergic disease by restraining T follicular helper 2 differentiation

Allergic diseases are common, affecting more than 20% of the population. Genetic variants in the TGFβ pathway are strongly associated with atopy. To interrogate the mechanisms underlying this association, we examined patients and mice with Loeys-Dietz syndrome (LDS) who harbor missense mutations in the kinase domain of TGFΒR1/2. We demonstrate that LDS mutations lead to reduced TGFβ signaling and elevated total and allergen-specific IgE, despite the presence of wild-type T regulatory cells in a chimera model. Germinal center activity was enhanced in LDS and characterized by a selective increase in type 2 follicular helper T cells (TFH2). Expression of Pik3cg was increased in LDS TFH cells and associated with reduced levels of the transcriptional repressor SnoN. PI3Kγ/mTOR signaling in LDS naïve CD4+ T cells was elevated after T cell receptor cross-linking, and pharmacologic inhibition of PI3Kγ or mTOR prevented exaggerated TFH2 and antigen-specific IgE responses after oral antigen exposure in an adoptive transfer model. Naïve CD4+ T cells from nonsyndromic allergic individuals also displayed decreased TGFβ signaling, suggesting that our mechanistic discoveries may be broadly relevant to allergic patients in general. Thus, TGFβ plays a conserved, T cell-intrinsic, and nonredundant role in restraining TFH2 development via the PI3Kγ/mTOR pathway and thereby protects against allergic disease.

Distinct myeloid antigen presenting cells dictate differential fates of tumor-specific CD8 T cells in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) contains numerous protumor myeloid cells at the expense of antitumor dendritic cells (cDC1s). We identify that tumor antigenicity is a major determinant of myeloid composition and functionality. Neoantigen-tumors contained pro-tumor macrophages and a paucity of cDC1s whereas neoantigen+ tumors accumulate cDC1s via Xcr1 signaling and macrophages exhibit a diminished role. Effective immunotherapies increased splenic cDC1s, which were required for endogenous T cell expansion following α-PD-L1 and transferred effector and memory T cells. Batf3−/− mice, which lack cDC1s, failed to spontaneously generate tumor-specific CD8 T cells and were resistant to T cell therapy and α-PD-L1. In contrast, agonistic α-CD40 exhibited partial benefit in Batf3−/− mice and expanded atypical tumor-specific CD8 T cells. Monocyte depletion abrogated atypical tumor-specific CD8 T cell priming yet enhanced α-CD40-mediated antitumor activity in Batf3−/− mice. In contrast, α-Gr1 abrogated the therapeutic benefit of CD40 agonist in Batf3−/− mice. In sum, our study supports that CD40 agonist promotes a cDC1-dependent antitumor immunity and a monocyte-dependent protumor arm of immune system. These results further underscore an essential antigen presenting role for cDC1s in the expansion and differentiation of naïve, effector, and memory T cells into Klrg1+ potent cytotoxic effector T cells capable of targeting pancreatic cancer.

M.R. is supported by National Institutes of Health (NIH) T32 AI 007313 E.J.S. is supported by NIH T35 AI118620 I.M.S. is supported by NIH R01 CA249393, R01 CA255039, Department of Defense #PA200286, an American Association for Cancer Research (AACR) Pancreatic Cancer Action Network Career Development Award (17-20-25-STRO), an AACR Pancreatic Cancer Action Network Catalyst Award (19-35-STRO), American Cancer Society Institutional Research Grant (124166-IRG-58-001-55-IRG65).

TNF-α blockade improves immunotherapy efficacy by altering the tumor microenvironment and enhancing tumor-specific T cell function in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDA) is a particularly lethal malignancy with a 5-year survival rate of 9%. A recent phase 1 clinical trial suggests CD40 agonist has antitumor activity in some patients. We developed an orthotopic PDA mouse model to track tumor specific CD8 T cells, identify critical antitumor mechanisms, and determine pathways of immunotherapy resistance. Here, we exploit this model to uncover a novel combination immunotherapy that includes CD40 agonist, PD-L1 blockade and TNF-α neutralization (e.g., 4PT). Interfering with TNF-α significantly improves overall mouse survival and cure rate compared to CD40+PDL1 only (4P). Critically, 4PT enhanced the generation of tumor-specific long-lived effector and central memory T cells. TNF-α neutralization significantly reduced T cell exhaustion, as indicated by reduced Lag-3 and increased IFN-γ production by intratumoral tetramer+ CD8 T cells. Additionally, 4PT increased CD4+Foxp3− T cell frequency and decreased CD4+Foxp3+ T cells as compared to 4P-treated mice, consistent with enhanced antitumor CD4 T cell reactivity in the absence of chronic TNF-α signaling. Lastly, abrogating Tnfr1 significantly reduced splenic and intratumoral Ly6G+ granulocytes following 4P. Thus, disrupting TNF-α via genetic deletion or monoclonal antibodies alters the tumor microenvironment to promote highly functional tumor-specific CD8 T cells. We conclude that perturbation of TNF-α-mediated chronic inflammation is an appealing approach to enhance immunotherapy efficacy for pancreatic cancer patient treatment.

Supported by NIH 1R01CA249393-01A1

Dysregulated TGF-β Signaling Leads to Cell-Intrinsic Changes in T cell Development that Promote Allergic Inflammation

Variants in genes in the Transforming Growth Factor Beta (TGFβ) signaling pathway are associated with allergic diseases suggesting that this cytokine may be a central player in the allergic diathesis. The role of TGFβ in preserving T cell mediated self-tolerance is well appreciated but how disruption in this pathway promotes allergic inflammation is unclear. We previously demonstrated that patients with Loeys-Dietz Syndrome (LDS), an autosomal dominant disorder caused by mutations in TGFBR1 and TGFBR2, are highly predisposed to allergic disease. LDS patients and mice harboring a knock in allele (Tgfbr1mut) of an LDS mutation known to cause severe disease in humans exhibit higher levels of total and food specific IgE. These serologic changes were associated with higher frequencies of T follicular helper (Tfh) cells and lower T follicular regulatory (Tfr) cells. Using a mixed bone marrow and fetal liver chimera model, we showed that these alterations in T cell development are cell intrinsic. Chimera models also demonstrated that the TGFβ mutation drives higher IgE production despite the presence of wildtype Tregs. Furthermore OVA specific Tgfbr1mutOTII cells were more likely to accumulate in the peyers patch and differentiate into Tfh cells in response to orally ingested OVA. These findings correlated with increased AKT/pS6 signaling downstream of TCR in Tgfbr1mut T cells, and mTOR inhibition decreased Tgfbr1mut OTII Tfh cells in response to fed ova. Additionally, RNA sequence analysis of murine Tgfbr1mut Tfh cells revealed enhanced PI3K/AKT pathway activity. These findings suggest that TGFβ signaling plays an important role in T cell development and function via the PI3K/AKT pathway that when disrupted promotes allergic inflammation.