Biology subjects

Amadio, R.

Publications and source records attributed to Amadio, R..

5 recordsLinked to original sources

bioRxiv2024

The Arp2/3 complex maintains genome integrity and survival of epidermal Langerhans cells

Myeloid cells use intracellular actin networks for key cellular processes, including cell migration and chemotaxis, phagocytosis or macropinocytosis, as well as immune synapse formation. However, whether actin networks play any role in the development and/or survival of myeloid cells in tissues remains open. Here, we found that the Arp2/3 complex, which is responsible for the nucleation of branched actin networks, is needed for in vivo maintenance of epidermal Langerhans cells (LCs) throughout life. Mice harboring a genetic deletion of the Arpc4 subunit of the complex in myeloid cells form LC networks at birth, but these cells decline in numbers following a process reminiscent of premature cellular aging. By combining in vivo analyses of LCs with in vitro experiments on bone-marrow-derived dendritic cells, we found that Arpc4-deficient cells manage to progress through the cell cycle but accumulate DNA damage associated with aberrant nuclear shapes, lamina reduction and events of nuclear envelope rupture. These results provide the first evidence for a physiological role of Arp2/3 in maintenance of genome integrity and survival of immune cells in tissues.

cell biology↗

bioRxiv2024

Actin polymerization by WASp limits nuclear envelope rupture and inflammation in macrophages

Mutations in the immune-specific actin regulator WASp induce a proinflammatory state in myeloid cells, whose underlying causes remain poorly defined. Here, we applied microfabricated tools that mimic tissue mechanical forces to explore the role of WASp in connecting mechano-sensing to the activation of inflammatory responses in macrophages. We show that WASp-deficient macrophages carry alterations in nuclear structure and undergo increased blebbing and nuclear rupture when exposed to mechanical confinement. High-resolution imaging indicates that WASp drives the formation of protective perinuclear actin structures in response to confinement. Functionally, a proinflammatory gene signature linked to nuclear envelope rupture is preferentially active in confined WASp null macrophages, which partially depends on the cGAS-STING pathway of cytosolic DNA sensing. Analysis of transcriptional datasets of human and mouse tissue macrophages confirmed elevated inflammatory activation in WASp null cells. Together, these data uncover that WASp restricts pro-inflammatory activation of macrophages by preserving nuclear integrity in confined environments, providing novel clues to understand inflammatory activation in Wiskott-Aldrich Syndrome.

immunology↗

bioRxiv2024

DCs targeted therapy expands CD8 T cell responses to bona-fide neoantigens in lung tumors

Cross-presentation by type 1 cDCs (cDC1) is critical to induce and sustain antitumoral CD8 T cell responses to model antigens, in various tumor settings. However, the impact of cross-presenting cDC1 and the potential of DC-based therapies in tumors carrying varied levels of bona-fide neoantigens (neoAgs) remains unclear. Here we generated a non-small cell lung cancer model with distinct ranges of TMB and MHC-I neoepitopes to test immunogenicity and response to Flt3L+CD40 (DC-therapy). We found that cDC1 are required to broaden the pattern of CD8 responses to basal and acquired neoAgs and DC-therapy strongly inhibits the growth of TMBhigh tumors. In contrast, TMBlow tumors induce weaker responses that are not sufficient to block progression. scRNA transcriptional analysis, immune profiling and functional assays show that DC-therapy triggers the accumulation of lung cDC1 with increased immunostimulatory properties and CD8 T cells with enhanced cytotoxic functions and reduced exhaustion, most prominently in neoAgshigh tumors. We conclude that boosting cDC1 activity is critical to broaden the diversity of anti-tumoral CD8 T cell responses and to leverage neoAgs content for therapeutic advantage.

immunology↗

bioRxiv2023

ALCAM-mediated synapses between DC1 and CD8 T cells are inhibited in advanced lung tumors

Conventional type 1 dendritic cells (DC1) control anti-tumoral CD8 T responses, in lymph nodes and tumor tissues. T-cell activation depends on the establishment of a tight physical interaction with antigen-presenting cell, the immunological synapse (IS). The molecular determinants of DC1-CD8 IS in tumor tissues and how they are regulated during cancer progression remain poorly investigated. Using a reporter for DC1 in a genetic model of non-small cell lung cancer (KP-XCR1venus) we show that IS in lung tissues are abundant and productive at early stages of tumor development but progressively diminish in advanced tumors. Transcriptional profiling and flow cytometry of lung resident DC1 identified a module of adhesion molecules downregulated in advanced tumors. We focused on ALCAM and LFA-1, ligands for CD6 and ICAM-1 on T cells, to investigate their role and functional impact. By immobilizing single receptor agonists on artificial cell surfaces, we demonstrate that ALCAM and LFA-1 are sufficient to trigger cytoskeletal remodeling in early tumor DC1, whereas late tumors DC1 are not responsive. Blocking ALCAM-CD6 interactions in functional assays impairs the acquisition of effector functions in CD8 T cells. Together these data highlight that adhesion molecules required to establish IS in early, immune-reactive, tumors are targeted during tumor progression blunting cross-talk within the IS.

immunology↗

bioRxiv2023

Tim4 enables large peritoneal macrophages to cross-present tumor antigens at early stages of tumorigenesis

Cross-presentation of tumor antigens by subsets of macrophages at different stages along tumor progression may have divergent impacts on anti-tumoral immune responses. Here we show that TIM4+ large peritoneal macrophages (LPM) avidly capture tumor cells and cross-present tumor-associated antigens at early stages of peritoneal infiltration by ovarian cancer cells. The phosphatidylserine (PS) receptor TIM4 promotes maximal uptake and triggers inflammatory and metabolic gene programs in combination with cytoskeletal remodeling and upregulation of transcriptional signatures related to antigen processing. At the cellular levels, TIM4 is recruited with F-actin at the phagocytic cup and translocates in nascent phagosomes, controlling the kinetic of phagosomal acidification and cargo degradation. TIM4 deletion abrogates cross-presentation of tumor-associated antigens and blunts expansion of effector CD8 T cells at tumor inception. In addition, targeting tumor antigens to LPM by PS liposomes can trigger CD8 T cell activation. Together these results suggest that TIM4 enables LPMs to scan the antigenic content of incoming tumor cells to promote immune surveillance by CD8 T cells and, at defined temporal windows, may be exploited for therapeutic purposes.

immunology↗