Anti-PD1 does not improve pyroptosis induced by γδ T cells but promotes tumor regression in a pleural mesothelioma mouse model

Our plain-English summary of Anti-PD1 does not improve pyroptosis induced by γδ T cells but promotes tumor regression in a pleural mesothelioma mouse model, by K.S. Lui, Z. Ye, H.C. Chan, et al (Frontiers in Immunology, 2023).

The study

• Authors: K.S. Lui, Z. Ye, H.C. Chan, Y. Tanaka, A.K.L. Cheung
• Journal: Frontiers in Immunology
• Published: 2023;14:1282710
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Introduction: Mesothelioma is an aggressive tumor in the pleural cavity that is difficult to treat. Diagnosis is usually late with minimal treatment options available for the patients and with unfavorable outcomes. However, recent advances in immunotherapy using γδ T cells may have potential against mesothelioma, given its ample tumoricidal and tumor-migratory properties could allow its infiltration to the widespread tumor mass. Thus, we hypothesize that Vδ2 T cells can perform cytotoxic activities against mesothelioma especially when combined with immune checkpoint blocker against PD-1.

Methods: Human Vδ2 T cells were expanded from peripheral blood mononuclear cells using Tetrakis-pivaloyloxymethyl 2-(thiazole-2-ylamino) ethylidene-1,1-bisphosphonate (PTA) plus IL-2 for 13 days, before used to test for cytotoxicity against mesothelioma cell lines. Mesothelioma-bearing mice was established by Intrapleural administration of mesothelioma cell lines to test for the efficacy of Vδ2 T cells plus anti-PD-1 antibody combination treatment. Pyroptosis was evaluated by cell morphology, western blot analysis, and ELISA experiments. Flow cytometry was used to examine expression of BTN2A1, BTN3A1, PD-L1, PD-L2 on mesothelioma cell lines. Immunofluorescence staining was performed to detect Vδ2 T cells post adoptive transfer and characteristics of pyroptosis in ex vivo mesothelioma tissue sections.

Results: Indeed, our data demonstrated that Vδ2 T cells killing mesothelioma can be enhanced by anti-PD-1 antibody in vitro, especially for high PD-1 expressing cells, and in vivo in the intrapleural mesothelioma mice model established by us. Adoptive transfer of Vδ2 T cells into these mice leads to tumor regression by 30-40% compared to control. Immunofluorescence of the tumor section confirmed infiltration of Vδ2 T cells into the tumor, especially to cells with BTN2A1 expression (a Vδ2 T cell activating molecule) despite PD-L1 co-localization. Interestingly, these cells co-expressed cleaved gasdermin D, suggesting that pyroptosis was induced by Vδ2 T cells. This was verified by Vδ2 T/mesothelioma co-culture experiments demonstrating membrane ballooning morphology, increased cleaved caspase-3 and gasdermin E, and upregulated IL-1β and IL-18.

Discussion: Vδ2 T cells plus anti-PD1 exhibited cytotoxicity against mesothelioma in vivo. However, we found no advantage for anti-PD-1 against PD-1 high expressing Vδ2 T cells in promoting pyroptosis. Taken together, our work demonstrated that Vδ2 T cells combined with anti-PD-1 antibody can be developed as a potential combination immunotherapy for mesothelioma.

Copyright © 2023 Lui, Ye, Chan, Tanaka and Cheung.

In plain English

This laboratory and animal study tested human Vδ2 (gamma-delta) T cells, with or without anti-PD-1 (nivolumab), against pleural mesothelioma. Vδ2 T cells were expanded from blood mononuclear cells with PTA plus IL-2, then tested against luciferase-tagged MSTO-211H and NCI-H2052 cells and in NSG mice given these cells intrapleurally. In vitro, PD-1lo Vδ2 T cells lysed up to about 25% of targets and PD-1hi cells about 12% (MSTO-luc) and 10% (H2052-luc); anti-PD-1 doubled killing by PD-1hi cells significantly, but not significantly for PD-1lo cells. In MSTO-luc mice, two doses of PD-1lo or PD-1hi Vδ2 T cells plus anti-PD-1 reduced tumour growth by about 67% and 58% versus PBS controls; controls survived 17 days, treated mice up to 21 days. Co-culture with MSTO-luc cells produced membrane ballooning, cleaved caspase 3 and gasdermin E and raised IL-18 and IL-1β; anti-PD-1 increased cleaved caspase 3 at the 10:1 ratio but not IL-18 or IL-1β. For H2052-luc, cleavage of caspase 3, gasdermin E and IL-18 was reported only at 10:1, without IL-1β. The authors concluded the combination could be developed as a potential immunotherapy for mesothelioma.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Experimental laboratory study: in vitro co-culture of human Vδ2 T cells with human mesothelioma cell lines plus in vivo adoptive transfer experiments in an intrapleural xenograft mouse model
• Who was studied: Human mesothelioma cell lines MSTO-211H and NCI-H2052 (luciferase-transduced), human Vδ2 T cells expanded from peripheral blood mononuclear cells from Hong Kong Red Cross whole blood, and NSG immunodeficient mice aged 4-6 weeks (groups of 3 to 6 mice for MSTO-luc, 4-5 mice for H2052-luc)
• Exposure: Treatment with PTA/IL-2-expanded human Vδ2 T cells (1 x 10^7 cells intravenously, one or two doses), with or without the anti-PD-1 antibody nivolumab given intraperitoneally; in vitro co-culture at effector:target ratios including 10:1, 5:1 and 2.5:1. Not an asbestos exposure study.
• Main results:
  • In vitro, PD-1lo Vδ2 T cells showed cytotoxicity up to about 25% against MSTO-luc and H2052-luc, while PD-1hi Vδ2 T cells gave about 12% and about 10% cytotoxicity respectively
  • Anti-PD-1 significantly increased killing by PD-1hi Vδ2 T cells about 2-fold, but the increase for PD-1lo cells was not statistically significant
  • In MSTO-luc bearing mice, one intravenous dose of PD-1lo or PD-1hi Vδ2 T cells reduced tumour growth by about 48% and about 36% respectively, measured by tumour luciferase activity
  • In MSTO-luc mice, two doses of PD-1hi Vδ2 T cells with anti-PD-1 gave about 58% reduction in tumour growth versus PBS control, and two doses of PD-1lo Vδ2 T cells with anti-PD-1 about 67% reduction
  • Survival of MSTO-luc control mice was 17 days; mice receiving PD-1lo or PD-1hi Vδ2 T cells with anti-PD-1 survived up to 21 days
  • In H2052-luc mice, two versus one dose of PD-1hi Vδ2 T cells reduced tumour growth by about 37% and about 19%; with anti-PD-1 the one- and two-dose regimens reduced growth by about 28% and about 49%
  • Vδ2-TCR positive cells were found in 14% of the tumour area after the two-dose treatment compared with 9% after one dose, located near BTN2A1-expressing tumour cells
  • In MSTO-luc co-culture, cleaved caspase 3 rose, particularly at the 10:1 effector:target ratio, and anti-PD-1 further raised cleaved caspase 3 at 10:1, with a corresponding effect on gasdermin E cleavage
  • In MSTO-luc co-culture, active IL-18 and released IL-1β increased at the 10:1 ratio, but anti-PD-1 did not increase either
  • In H2052-luc co-culture, cleavage of caspase 3, gasdermin E and IL-18 was found only at the 10:1 ratio, with no effect on gasdermin D, caspase 4 or IL-1β
  • The authors also summarised the co-culture work as inducing active IL-18 and IL-1β in MSTO-luc but not H2052-luc cells, which they suggested indicated greater resistance of H2052-luc cells
  • In H2052-luc tumour sections, cleaved gasdermin D next to Vδ2-TCR positive cells was seen in 19% after two-dose treatment versus 8% after one dose, with no noticeable difference between treatment with and without anti-PD-1
  • By flow cytometry, BTN2A1 was expressed on about 6.2% of MSTO-luc and about 4.6% of H2052-luc cells, with under 1% co-expressing BTN2A1 and BTN3A1
• The authors' conclusion: The authors concluded that Vδ2 T cells plus anti-PD-1 showed cytotoxicity against mesothelioma in vivo, that anti-PD-1 gave no advantage for promoting pyroptosis by PD-1 high Vδ2 T cells, and that the combination could be developed as a potential immunotherapy for mesothelioma
• Limitations the authors state:
  • The authors noted that complete tumour elimination may need far more Vδ2 T cells, raising concerns about the physiological burden of transferring nearly 200 times more cells than the tumour
  • The authors stated that the combination therapy needs further refinement and that profiling of different clinical mesotheliomas would be necessary
  • The authors reported that cleaved caspase 4 was not induced, so the mechanism of gasdermin D cleavage was not established

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Mesothelioma, Pleural Cavity, Immunotherapy, PD-L1.

Related studies

• Dietary vitamin D supplementation does not reduce the incidence or severity of asbestos-induced mesothelioma in a mouse model — C. Robinson, S. Woo, et al. (2014)
• Antitumor-specific T-cell responses induced by oncolytic adenovirus ONCOS-102 (AdV5/3-D24-GM-CSF) in peritoneal mesothelioma mouse model — L. Kuryk, A.W. Møller, et al. (2018)
• Novel combinatorial therapy of oncolytic adenovirus AdV5/3-D24-ICOSL-CD40L with anti PD-1 exhibits enhanced anti-cancer efficacy through promotion of intratumoral T-cell infiltration and modulation of tumour microenvironment in mesothelioma mouse model — M. Garofalo, M. Wieczorek, et al. (2023)
• The Inhibitory Effects of Anti-ERC/Mesothelin Antibody 22A31 on Colorectal Adenocarcinoma Cells, within a Mouse Xenograft Model — G. Taniguchi, K. Kajino, et al. (2022)
• The PD-L1/PD-1 pathway promotes dysfunction, but not "exhaustion", in tumor-responding T cells from pleural effusions in lung cancer patients — H. Prado-Garcia, S. Romero-Garcia, et al. (2017)
• Tretinoin improves the anti-cancer response to cyclophosphamide, in a model-selective manner — C.M. Tilsed, M.L.O. Morales, et al. (2024)

Browse more research in Frontiers in Immunology, or return to medical research.