Citations

Abstract Introduction Immunotherapy approaches against glioblastoma (GBM) such as immune checkpoint inhibitors (ICI), dendritic cell vaccination, and CAR-T have failed to durably cure most patients. Studies analyzing tumors from ICI responders show that abundance of CD4 and CD8 T cells prior to initiation of therapy predicts responsiveness. Thus, targeting the microenvironment to promote CD4 activity may synergize with ICI. The glioblastoma microenvironment contains high proportions of monocyte-derived macrophages which have potent immunosuppressive capabilities. Characterizing and targeting these immunosuppressive programs is a promising strategy for designing effective combination immunotherapies for glioblastoma patients. Methods We analyzed human glioblastoma snRNAseq datasets to find signaling receptors associated with myeloid immunosuppression and employed murine models of glioblastoma for functional validation. Results By analyzing patient-derived -omics datasets, we identified an understudied TNF-superfamily receptor, Fn14, as being upregulated in glioblastoma-associated myeloid cells with immunosuppressive gene signatures. Using in vitro approaches, we found that Fn14 activation in the tumor microenvironment can drive cytokines implicated in GBM immunosuppression such as IL6, IL1B, and IL8. Thus, Fn14 may serve as a surface marker for microenvironment-remodeling myeloid cells recruited to the tumor from peripheral circulation. Furthermore, in murine models of glioblastoma, we discovered Fn14 KO among glioblastoma-associated myeloid cells increases conventional dendritic cell type 1 (cDC1) and Th1 CD4+ T cell abundance in the tumor microenvironment and significantly prolongs survival. Conclusion These results suggest that blocking Fn14 in glioblastoma-associated myeloid cells can enhance Th1 immunity. Thus, Fn14 may represent a promising dual therapy target. Funding Source NIH Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Background Immune exclusion inhibits antitumor immunity and response to immunotherapy, but its mechanisms remain poorly defined. In triple-negative breast cancer (TNBC), an aggressive and generally immune-rich subtype, an immune-cold microenvironment predicts poor prognosis due to a limited response to chemotherapy and immune checkpoint inhibitors. This study aimed to identify mechanisms regulating immune infiltration in TNBC. Methods We performed spatial transcriptomic analysis comparing immune-enriched versus immune-cold treatment-naïve TNBCs. Functional analyses, including loss-of-function and reconstitution experiments, were conducted to investigate the role of trophoblast cell-surface antigen 2 (TROP2), a key target of anticancer antibody drug conjugates (ADCs), in promoting TNBC progression. A humanized TROP2 syngeneic TNBC model was used to assess the effects of TROP2-targeting in combination with anti-programmed cell death protein 1 (PD-1) therapy. Additionally, data from patients treated with immune checkpoint blockade were used to test hypotheses from the preclinical findings. Results We reveal that TROP2 controls barrier-mediated immune exclusion in TNBC through claudin 7 association and tight junction regulation. TROP2 expression is inversely correlated with T-cell infiltration and predicts poor outcomes in TNBC. We demonstrate that TROP2 is sufficient to drive tumor progression in vivo in a CD8 T cell-dependent manner, while its loss deregulates expression and localization of multiple tight junction proteins, enabling T-cell infiltration. We show that TROP2 targeting via hRS7, the antibody component of the ADC sacituzumab govitecan, enhances the anti-PD-1 response and improves T-cell accessibility and effector function. Correspondingly, TROP2 expression is highly associated with lack of response to anti-PD-1 therapy in human breast cancer. Conclusions This study defines a new mechanism of barrier-mediated immune exclusion in cancer controlled by TROP2-dependent tight junctions. This mechanism drives tumor progression but can be targeted via TROP2-directed therapy to activate antitumor immunity and enhance immunotherapy response.

Abstract Lung cancer is the leading cause of cancer-related deaths worldwide, and despite advances in treatment, immune suppression remains an obstacle to effective therapy. Effector CD4+ T cells (CD4+ Teff) are critical for antitumor immunity, but their function is often inhibited by regulatory T cells (Treg), which accumulate in lung tumors and mediate suppressive functions through multiple mechanisms. This suppression leads to tumor progression and poor patient outcomes. However, the mechanisms underlying Treg-mediated suppression are not fully understood. Herein, we identify the extracellular adenosine 5-triphosphate receptor P2RX7 as a key regulator of Treg function in lung tumors. In a murine lung cancer model induced by Lewis lung carcinoma cells, we found that P2RX7 enhanced the suppressive capacity of tumor-infiltrating Tregs, promoting tumor growth. In T cell–specific P2RX7-knockout (P2RX7-KO) mice, reduced Treg infiltration was accompanied by increased CD4+ Teff accumulation and improved tumor control. Treg-specific P2RX7-KO mice exhibited reduced tumor growth, confirming a Treg-intrinsic role of P2RX7. Suppression assays revealed that tumor-infiltrating wild-type Tregs had greater suppressive activity compared with P2RX7-KO Tregs, which failed to inhibit type 1 and follicular helper T–like responses. This was associated with increased tumor-specific IgG production by lung B cells in P2RX7-KO mice. We also observed that wild-type Tregs expressed higher levels of the immunosuppressive molecule CTLA-4 when compared with P2RX7-KO Tregs. Thus, we conclude that P2RX7 expression on Tregs is essential for their suppressive function in lung cancer and targeting P2RX7 may constitute a strategy to improve lung cancer treatment by alleviating Treg-mediated immune suppression.

Abstract Description The presence of Foxp3+CD4+ regulatory T cells (Tregs) hinders the protective antitumor T cell responses to lung cancer. The accumulation of Tregs is linked to lung cancer progression, resulting in poorer survival rates. However, the mechanisms behind this accumulation are not fully understood. Tregs express elevated levels of the extracellular ATP (eATP) receptor P2RX7 in both human and mouse lung cancer. Here, we show that P2RX7 is crucial for the accumulation of Tregs in lung tumor, promoting tumor growth in a murine lung cancer model. We observed, in T cell-specific P2RX7-KO mice (CD4-cre P2rx7fl/fl), reduced Treg infiltration and a concomitant increase in tumor CD4+ effector T cells, leading to better tumor control. In contrast, P2RX7-KO Tregs accumulated in mediastinal lymph nodes, suggesting that blocking P2RX7-KO signaling impairs the Tregs migratory ability. P2RX7+ Tregs had increased expression of T-bet and KLRG1, which are associated with greater suppressive function. Finally, Treg-specific P2RX7-KO mice (Foxp3-Cre-ERT2 P2rx7fl/fl) had reduced tumor growth and Treg tumor accumulation, indicating that P2RX7 controls lung tumor Tregs in a cell-intrinsic way. These results suggest that P2RX7 promotes lung tumor Treg infiltration and subsequent loss of cancer control. They also suggest that P2RX7 blockade can be used as a therapy to improve lung cancer control, which we are currently exploring in proof-of-concept experiments. Funding Sources Mayo Clinic and National Institutes of Health (NIH - H.B.d.S.: R01 AI170649) Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Abstract Description Developing a universal influenza vaccine requires understanding how lung-resident memory CD4+ T cells are formed. These cells remain in the lung for a long time and strengthen the immune response to secondary infections. Tissue-resident helper cells (TRH), a subset of memory T cells, share characteristics with follicular helper cells (TFH) and boost the IgA and IgG production by lung-resident B cells. TRH cells express elevated levels of the extracellular ATP (eATP) sensor P2RX7. Here we demonstrate that P2RX7 ablation on T cells impairs the establishment of flu-specific TRH cells. P2RX7-induced decrease of TRH cells negatively impacted the protection against homologous challenge, since T cell-specific P2RX7-KO mice exhibit worse control of viral load than WT mice. P2RX7-KO mice also showed a reduction in flu-specific lung-resident germinal center-like B cells and lower levels of IgA and IgG in the lungs. P2RX7-KO did not induce major changes in the numbers of TFH-induced responses in the draining lymph nodes. Our single-cell RNAseq showed reduced expression of mitochondrial genes in P2RX7-KO TRH cells, which reflects decreased mitochondrial content presence in these cells. We observed an aberrant metabolic pathway usage by P2RX7-KO TRH cells, which beyond having less mitochondria also cease to utilize glycolytic metabolism to support protein synthesis. Our findings suggest the eATP-P2RX7 axis is required to establish TRH cells that protect against influenza. Funding Sources Mayo Clinic and National Institutes of Health (NIH - H.B.d.S.: R01 AI170649) Topic Categories Mucosal and Regional Immunology (MUC)

Abstract Description Persistent exposure to antigens and immunosuppressive signals in tumors or chronic infections drives CD8+ T cell exhaustion (Tex), a programmed state of T cell dysfunction. While efforts have been made to combat Tex through immunotherapies, they often fail to induce lasting protective effects. Exhausted CD8+ T cells consist of various subsets with distinct transcriptional, functional, and metabolic features. Among these subsets, progenitor exhausted CD8+ T cells (Tprog) are important: they are metabolically quiescent, retain stemness capacity and respond better to checkpoint blockade therapy (e.g., anti-PD1). Here, we report that, in response to chronic viral infection (LCMV Clone 13), P2RX7 is crucial for the establishment of Tprog cells. P2RX7-KO CD8+ T cells had decreased numbers of Tprog cells. P2RX7-KO Tprog cells lose metabolic quiescence, displaying increased glycolytic function and loss of mitochondrial respiration dependence. Our meta-analyses of gene (scRNAseq) and protein (LegendScreen assay) expression suggest that P2RX7-KO Tprog cells undergo abnormal exhaustion differentiation paths, and express reduced levels of integrin beta-1 (ITGB1), a molecule associated with lymphoid residency of Tprog cells. Finally, we found that P2RX7 is crucial for exhausted CD8+ T cells to respond to anti-PD1 in vivo. These data open the possibility of using P2RX7 agonism to boost the efficacy of existing checkpoint blockade immunotherapies aimed to revitalize CD8+ T cell responses. Funding Sources NIH Grants K99/R00A139381 and R01A170649 Topic Categories Lymphocyte Differentiation and Peripheral Maintenance (LYM)

Abstract Description Immune responses to allergens vary depending on the route of sensitization, but the mechanisms behind these differences are not clear. Damage signals from the microenvironment dictate the immune response magnitude and may regulate route of sensitization differences. Extracellular ATP (eATP) is a danger signal released by inflamed tissues and sensed by immune cells via P2RX7. The role of P2RX7 in CD4+ Th2 cell responses to allergen is unclear, with past reports suggesting opposite effects of P2RX7 knockout (KO). Here, we tracked the role of P2RX7 on CD4+ T cell-mediated lung allergy in response to different routes of sensitization. Comparing Papain + Ovalbumin (OVA) intranasal versus subcutaneous sensitization, we found increased lung type 2 inflammation and lung CD4+CD69+GATA3+ T cells in response to the subcutaneous route, compared to intranasal route. P2RX7-KO led to decreased lung CD4+ Th2 cell responses and reduced inflammation in mice exposed to subcutaneous, but not intranasal sensitization. Subcutaneous OVA + Papain led to a stronger eosinophilic response, while both eosinophils and neutrophils were elicited by intranasal route. Our results indicate that sensing of eATP through P2RX7 exacerbate the intensity of subcutaneous allergen-induced Th2 responses. We are currently comparing the Th2 responses induced by subcutaneous versus intranasal allergen sensitization, and how P2RX7 oppositely regulate such responses. Funding Sources NIH K99/R00A139381 NIH R01A170649 Topic Categories Immediate Hypersensitivity, Asthma, and Allergic Responses (HYP)

SUMMARY Tuberculosis induces diverse lesions, such as necrotic pneumonia, contributing to disease progression and transmission. Despite advances in understanding the role of ATP-gated P2RX7 ion channels in developing severe forms of tuberculosis, the regulation of this important signaling pathway remains unclear. Herein, we show that the ectonucleotidase CD39 plays an essential regulatory role in TB progression by preventing lung tissue damage, bacterial dissemination, and excessive inflammatory responses. Mechanistically, through its enzymatic activity on the cellular surface, CD39 protects infected macrophages from undergoing necrotic death mediated by P2RX7 activation. We proposed that by protecting macrophages from P2RX7-mediated cell death and bacterial dissemination, CD39 prevents the development of necrotic lesions. Altogether, these findings uncover a significant role for CD39 as an essential component of the molecular regulation underlying the development of severe tuberculosis. GRAPHICAL ABSTRACT Brief In tuberculosis, necrotic granuloma-like structures release extracellular ATP (eATP), which triggers P2RX7-mediated immune cell death. CD39 degrades eATP, preventing P2RX7 activation and promoting macrophage survival, thereby limiting inflammation, tissue damage, and bacterial dissemination.

ABSTRACT Lung cancer is the leading cause of cancer-related deaths worldwide and, despite treatment advances, immune suppression remains an obstacle to effective therapy. Effector CD4 + T cells (CD4 + Teffs) are critical for antitumor immunity, but their function is often inhibited by regulatory T cells (Tregs), which accumulate in lung tumors and perform suppressive functions through multiple mechanisms. This suppression leads to tumor progression and poor patient outcomes. However, the mechanisms underlying Treg-mediated suppression are not fully understood. Here, we identify the extracellular ATP receptor P2RX7 as a key regulator of Treg function in lung tumors. Using a murine lung cancer model induced by Lewis lung carcinoma cells, we demonstrate that P2RX7 enhances the suppressive capacity of tumor-infiltrating Tregs, promoting tumor growth. In T cell-specific P2RX7-KO mice, reduced Treg infiltration was accompanied by increased CD4 + Teff accumulation and improved tumor control. Treg-specific P2RX7-KO mice exhibit reduced tumor growth, confirming a cell-intrinsic role of P2RX7 in Tregs. Suppression assays revealed that tumor-infiltrating WT Tregs have greater suppressive activity compared to P2RX7-KO Tregs, which failed to inhibit type 1 and Tfh-like responses. This was associated with increased tumor-specific IgG production by lung B cells in P2RX7-KO mice. We also observed that WT Tregs express higher levels of the immunosuppressive surface molecule CTLA-4 when compared to P2RX7-KO Tregs. In summary, we show that P2RX7 expression on Tregs is essential for their suppressive function in lung cancer, and targeting of P2RX7 may constitute a novel strategy to improve lung cancer treatment by alleviating Treg-mediated immune suppression.

ABSTRACT Background Immune exclusion inhibits anti-tumor immunity and response to immunotherapy, but its mechanisms remain poorly defined. In triple-negative breast cancer (TNBC), an aggressive and generally immune-rich subtype, an immune-cold microenvironment predicts poor prognosis due to a limited response to chemotherapy and immune checkpoint inhibitors. This study aimed to identify mechanisms regulating immune infiltration in TNBC. Methods We performed spatial transcriptomic analysis comparing immune-enriched versus immune-cold treatment-naïve TNBCs. Functional analyses, including loss-of-function and reconstitution experiments, were conducted to investigate the role of Trophoblast Cell-Surface Antigen 2 (TROP2), a key target of anti-cancer Antibody Drug Conjugates (ADCs), in promoting TNBC progression. A humanized TROP2 syngeneic TNBC model was used to assess the effects of TROP2-targeting in combination with anti-PD1 therapy. Additionally, data from patients treated with immune checkpoint blockade were used to test hypotheses from the preclinical findings. Results We reveal that TROP2 controls barrier-mediated immune exclusion in TNBC through Claudin 7 association and tight junction regulation. TROP2 expression is inversely correlated with T cell infiltration and predicts poor outcomes in TNBC. We demonstrate that TROP2 is sufficient to drive tumor progression in vivo in a CD8 T cell-dependent manner, while its loss deregulates expression and localization of multiple tight junction proteins, enabling T cell infiltration. We show that TROP2 targeting via hRS7, the antibody component of the ADC Sacituzumab govitecan (SG), enhances the anti-PD1 response and improves T cell accessibility and effector function. Correspondingly, TROP2 expression is highly associated with lack of response to anti-PD1 therapy in human breast cancer. Conclusions This study defines a new mechanism of barrier-mediated immune exclusion in cancer controlled by TROP2-dependent tight junctions. This mechanism drives tumor progression but can be targeted via TROP2-directed therapy to activate anti-tumor immunity and enhance immunotherapy response. What is already known on this topic Barrier-mediated immune exclusion is emerging as a mechanism of immune evasion in cancer such as triple-negative breast cancer (TNBC), but its molecular underpinnings remain poorly understood. TROP2 is a surface glycoprotein targeted by antibody-drug conjugates such as Sacituzumab govitecan, yet its functional role beyond drug delivery has been unclear. What this study adds This study identifies TROP2 as a key regulator of tight junction-mediated immune exclusion in TNBC, independent of its intracellular signaling function. TROP2 promotes an immune-cold tumor microenvironment by enforcing mechanical barriers that limit T cell infiltration. How this study might affect research, practice or policy These findings establish TROP2 as a functional driver of immune evasion and provide a mechanistic rationale for combining TROP2-targeting therapies with immune checkpoint inhibitors to overcome resistance in immune-excluded tumors.