Biology subjects

Ardolino, M.

Publications and source records attributed to Ardolino, M..

7 recordsLinked to original sources

bioRxiv2026

Characterization of tumor interactions with the immune system in an autochthonous mouse model of glioblastoma

BackgroundGlioblastoma is an aggressive and incurable brain tumor. Clinical trials of immune checkpoint inhibitors showed no clinical benefit in glioblastoma when given after surgery. However, a clinical trial in which PD1 inhibition was given prior to second surgery did show pharmacodynamic evidence for activity. This suggests the possibility that immune checkpoint inhibitors may be more effective in a setting where large tumors are present. Here we have studied immune responses to large tumors in an autochthonous mouse model of glioblastoma. MethodsGlioblastoma was induced by transfection with oncogenic plasmids injected directly into the lateral ventricle of neonatal mice. Immune responses were assessed using a combination of spectral flow cytometry and immunohistochemistry. ResultsThere was a marked immune response to large tumors, with significant increases in CD4 T cells and dendritic cells. T cell changes occurred primarily at leptomeningeal/perivascular border sites. A large proportion of CD4 T cells expressed PD1 and half of these were regulatory T cells. NK cells were also increased in mice with large tumors, but were predominantly in immature states. The mouse model accurately recapitulates the formation of palisading necroses. These contain apoptotic cells and avidly recruit myeloid cells that are induced to express large amounts of TGF{beta}. ConclusionsLarge glioblastoma tumors generate a border site population of PD1 positive T cells that may explain the pharmacodynamic response in neoadjuvant trials, and a palisading necrosis-driven immunosuppressive mechanism that may explain why responses are insufficient to provide a significant clinical benefit. KEY POINTSThe SB mouse model accurately recapitulates immune features of human glioblastoma Large tumors induce a significant border site immune response Palisading necroses in large tumors counter this with a strong immunosuppressive response IMPORTANCE OF STUDYImmune checkpoint inhibitors have not shown efficacy in glioblastoma when used post-surgery, but do show pharmacodynamic activity when used in patients prior to second surgery (i.e. neoadjuvant). This suggest the possibility that immune checkpoint inhibition is more effective when large tumors are present. Using a clinically-relevant autochthonous mouse model, we show here that large tumors induce an immune response that is evident in leptomeningeal border sites. Large tumors in this mouse model also generate palisading necroses, a well-known diagnostic feature in glioblastoma tumors. These palisading necroses generate large amounts of TGF{beta}, providing a mechanism by which large tumors can suppress border site immune responses. This further supports the concept that palisading necroses are drivers of glioblastoma malignancy and suggests novel strategies to enhance responses to immune checkpoint inhibition in this cancer.

cancer biology↗

bioRxiv2024

LAG3 marks activated but hyporesponsive NK cells.

Natural Killer (NK) cells are critical for immunosurveillance yet become dysfunctional in contexts such as chronic stimulation by viral infections or cancer. This phenomenon is similar to T cell exhaustion but less well characterized, which limits therapeutic interventions. As shown for T cells, NK cells often display an increased expression of immune checkpoint proteins (ICP) following chronic stimulation, and ICP blockade therapies are currently being explored for several cancer types, which have remarkable patient benefits. Nevertheless, the nature of ICP expression in NK cells is still poorly documented. In this study, we aimed to identify the conditions that lead to and the phenotype of immune checkpoint LAG3 (Lymphocyte-activation gene 3) expressing NK cells. Using various experimental models, we found that LAG3 is expressed by murine NK cells upon activation in different contexts, including in response to cancer and acute viral infections. LAG3 marks a subset of immature, proliferating and activated cells, which, despite activation, have a reduced capacity to respond to a broad range of stimuli. Further characterization also revealed that LAG3+ NK cells exhibit a transcriptional signature similar to that of exhausted CD8+ T cells. Taken together, our results support the use of LAG3 as a marker of dysfunctional NK cells across diverse chronic and acute inflammatory conditions.

immunology↗

bioRxiv2024

Preventing surgery induced immune suppression and metastases by inhibiting PI3K-gamma signalling in Myeloid-Derived Suppressor Cells.

Myeloid derived suppressor cells (MDSCs) have a dominating presence in the postoperative period and mediate the suppression of Natural Killer (NK) cells and promotion of cancer metastases after surgery. However, their functional characteristics and effect on cellular immunity after surgery have not been comprehensively investigated. Here, we characterize the expansion of surgery-induced (sx) MDSCs via multi-colour flow cytometry, single-cell RNA sequencing, and functional ex vivo NK cell suppression assays. We then screened a small molecule library using our sx-MDSC:NK cell suppression assay to identify compounds that could inhibit sx-MDSCs. These studies provide evidence that PI3K-{gamma} signalling is upregulated in sx-MDSCs and blockade with PI3K-{gamma} specific inhibitors attenuates NK cell suppression in humans and mice and reduces postoperative metastases in murine models. Upregulated PI3K-{gamma} in sx-MDSCs is a potential pathway amenable to therapeutic targeting in the postoperative period. One Sentence SummaryThe suppressive mechanisms of surgery-induced myeloid derived suppressor cells use PI3K signalling and are amenable to PI3K-gamma specific inhibitors.

immunology↗

bioRxiv2023

CD8 T cell hyperfunction and reduced tumour control in models of advanced liver fibrosis

Immune dysfunction, both depression and hyperactivation, in liver disease contributes to significant morbidities and mortalities, depending on liver damage severity and etiology. The underlying causes of immune dysfunction in advanced liver disease, whether pathogen or host-mediated, remain unclear. We reported lasting generalized CD8+ T cell hyperfunction in individuals with advanced liver fibrosis in chronic HCV infection. The separation of viral and fibrosis-driven effects or the association of this phenomenon with clinical outcomes of advanced liver fibrosis remains to be determined. Here, a hepatotoxic murine model of liver fibrosis was used to decouple liver fibrosis from viral infection. Carbon tetrachloride (CCl4)-treated mice presented progressive liver fibrosis within {approx}12 weeks, resulting in severe diffuse fibrosis, focal necrosis and surrounding mixed inflammation; pathology similar to that of chronic HCV infection. Taking advantage of this model, we investigated if liver fibrosis caused systemic CD8+ T cell hyperfunction and evaluated its impact on host immune response. At peak liver fibrosis, circulating CD8+ T cells presented increased expression of IFN-{gamma} and granzyme B (GrzB) in comparison to control animals. CD8+ T cell hyperfunction arose by 8 weeks of CCl4 treatment and was sustained with continued liver insult. As a result, fibrotic mice were unable to resist an ectopic tumour challenge and were less responsive to immunotherapy. Furthermore, CD8+ T cell dysfunction was observed in other contexts of chronic liver insult such as high fat diet-induced liver steatosis, even in the absence of significant fibrosis. Collectively, this study shows the impact of chronic liver insult on systemic CD8+ T cell function and its association with impaired immune response, such as tumour surveillance.

immunology↗

bioRxiv2022

More than a ligand: PD-L1 promotes oncolytic virus infection via a metabolic shift that inhibits the type I interferon pathway.

Targeting the PD-1/PD-L1 axis has transformed the field of immune-oncology. While conventional wisdom initially postulated that PD-L1 serves as the inert ligand for PD-1, an emerging body of literature suggests that PD-L1 has cell-intrinsic functions in immune and cancer cells. In line with these studies, here we show that engagement of PD-L1 via cellular ligands or agonistic antibodies, including those used in the clinic, potently inhibits the type I interferon pathway in cancer cells. Hampered type I interferon responses in PD-L1-expressing cancer cells resulted in enhanced infection with oncolytic viruses in vitro and in vivo. Consistently, PD-L1 expression marked tumor explants from cancer patients that were best infected by oncolytic viruses. Mechanistically, PD-L1 suppressed type I interferon by promoting a metabolic shift characterized by enhanced glucose uptake and glycolysis rate. Lactate generated from glycolysis was the key metabolite responsible for inhibiting type I interferon responses and enhancing oncolytic virus infection in PD-L1-expressing cells. In addition to adding mechanistic insight into PD-L1 intrinsic function and showing that PD-L1 has a broader impact on immunity and cancer biology besides acting as a ligand for PD-1, our results will also help guide the numerous efforts currently ongoing to combine PD-L1 antibodies with oncolytic virotherapy in clinical trials. Once sentence summaryPD-L1 promotes oncolytic virus efficacy.

cancer biology↗

bioRxiv2021

A small molecule drug screening identifies colistin sulfate as an enhancer of Natural Killer cell cytotoxicity.

Because of their crucial role in tumor immunity, NK cells have quickly become a prime target for immunotherapies, with adoptive transfer of NK cells and the use of NK cell engagers quickly moving to clinical stage. On the other hand, only few studies have focused on small molecule drugs capable of unleashing NK cell against cancer. In this context, repurposing small molecule is an attractive strategy to identify new immunotherapies from already approved drugs. Here, we screened 1,200 FDA-approved drugs from the Prestwick Chemical Library, to identify compounds that increase NK cell cytotoxic potential. Using a high-throughput luciferase-release cytotoxicity assay, we found that the antibiotic colistin sulfate increased cytotoxicity of human NK cells towards cancer cells. The effect of colistin was short lived and was not observed when NK cells were pretreated with the drug, showing how NK cell activity was potentiated only when the compound was present at the time of recognition of cancer cells. Further studies are needed to uncover the mechanism of action and the pre-clinical efficacy of colistin sulfate in mouse cancer models.

immunology↗

bioRxiv2020

NK cells acquire PD-1 from the membrane of tumor cells.

Leucocytes often perform trogocytosis, the process by which cells acquire parts of the plasma membrane from interacting cells. Accumulating evidence indicates that trogocytosis modulates immune responses, but the underlying molecular mechanisms are unclear. Here, using two mouse models of leukemia, we found that cytotoxic lymphocytes perform trogocytosis at high rates with tumor cells. While performing trogocytosis, both Natural Killer and CD8+ T cells acquire the checkpoint receptor PD-1 from leukemia cells. In vitro and in vivo investigation revealed that PD-1 protein found on the surface of Natural Killer cells, rather than being endogenously expressed, was derived entirely from leukemia cells. Mechanistically, SLAM receptors were essential for PD-1 trogocytosis. PD-1 acquired via trogocytosis actively suppressed anti-tumor immunity, as revealed by the positive outcome of PD-1 blockade in PD-1-deficient mice. PD-1 trogocytosis was corroborated in patients with clonal plasma cell disorders, where Natural Killer cells that stained for PD-1 also stained for tumor cell markers. Our results, in addition to shedding light on a previously unappreciated mechanism underlying the presence of PD-1 on Natural Killer and cytotoxic T cells, reveal the immune-regulatory effect of membrane transfer occurring when immune cells contact tumor cells. Once sentence summaryNatural Killer cells are inhibited by PD-1 acquired from the surface of tumor cells via trogocytosis.

immunology↗