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Psoriasis is a chronic inflammatory skin disease with an autoimmune component and associated with joint inflammation in up to 30% of cases. To investigate autoreactive T cells, we developed an imiquimod-induced psoriasis-like inflammation model in K5-mOVA.tg C57BL/6 mice expressing ovalbumin (OVA) on the keratinocyte membrane, adoptively transferred with OT-I OVA-specific CD8+ T cells. We evaluated the expansion of OT-I CD8+ T cells and their localization in skin, blood, and spleen. scRNA-seq and TCR sequencing data from patients with psoriatic arthritis were also analyzed. In the imiquimod-treated K5-mOVA.tg mouse model, OT-I T cells were markedly expanded in the skin and blood at early time points. OT-I T cells in the skin showed mainly CXCR3+ effector memory phenotype, whereas in peripheral blood there was an expansion of CCR4+CXCR3+ OT-I cells. At a later time point, expanded OVA-specific T-cell population was found in the spleen. In patients with psoriatic arthritis, scRNA-seq and TCR sequencing data showed clonal expansion of CCR4+ TCM cells in the circulation and further expansion in the synovial fluid. Importantly, there was a clonotype overlap between CCR4+ TCM in the peripheral blood and CD8+ T-cell effectors in the synovial fluid. This mechanism could play a role in the generation and spreading of autoreactive T cells to the synovioentheseal tissues in psoriasis patients at risk of developing psoriatic arthritis.

iNKT cells account for a relevant fraction of effector T-cells in the intestine and are considered an attractive platform for cancer immunotherapy. Although iNKT cells are cytotoxic lymphocytes, their functional role in colorectal cancer (CRC) is still controversial, limiting their therapeutic use. Thus, we examined the immune cell composition and iNKT cell phenotype of CRC lesions in patients (n = 118) and different murine models. High-dimensional single-cell flow-cytometry, metagenomics, and RNA sequencing experiments revealed that iNKT cells are enriched in tumor lesions. The tumor-associated pathobiont Fusobacterium nucleatum induces IL-17 and Granulocyte-macrophage colony-stimulating factor (GM-CSF) expression in iNKT cells without affecting their cytotoxic capability but promoting iNKT-mediated recruitment of neutrophils with polymorphonuclear myeloid-derived suppressor cells-like phenotype and functions. The lack of iNKT cells reduced the tumor burden and recruitment of immune suppressive neutrophils. iNKT cells in-vivo activation with α-galactosylceramide restored their anti-tumor function, suggesting that iNKT cells can be modulated to overcome CRC-associated immune evasion. Tumor co-infiltration by iNKT cells and neutrophils correlates with negative clinical outcomes, highlighting the importance of iNKT cells in the pathophysiology of CRC. Our results reveal a functional plasticity of iNKT cells in CRC, suggesting a pivotal role of iNKT cells in shaping the tumor microenvironment, with relevant implications for treatment.

iNKT cells account for a relevant fraction of effector T-cells in the intestine. Although iNKT cells are cytotoxic lymphocytes, their role in colorectal cancer (CRC) remains controversial. From the analysis of colonic LPMCs of human and murine CRC specimens we report that tumor-infiltrating iNKT cells are characterized by an IL17/GM-CSF pro-tumorigenic phenotype, while maintaining cytotoxic properties in the adjacent non-tumoral tissue. Exposure of iNKT cells to the tumor-associated pathobiontFusobacterium nucleatumblunted their cytotoxic capability and enhanced iNKT cell-mediated neutrophils chemotaxis, which upregulated PMN-MDSC gene signatures and functions. Importantly,in vivostimulation of iNKT cells with αGalCer restored their anti-tumorigenic functions. Survival analyses demonstrated that human CRC co-infiltration by iNKT cells and tumor-associated neutrophils correlates with negative outcomes.Our results reveal a functional plasticity of human intestinal iNKT cells with pro- and anti-tumorigenic activities in CRC, suggesting an iNKT pivotal role in shaping the cancer developmental trajectory.

Growing evidence suggests that conventional dendritic cells (cDCs) undergo aberrant maturation in COVID‐19, which negatively affects T‐cell activation. The presence of effector T cells in patients with mild disease and dysfunctional T cells in severely ill patients suggests that adequate T‐cell responses limit disease severity. Understanding how cDCs cope with SARS‐CoV‐2 can help elucidate how protective immune responses are generated. Here, we report that cDC2 subtypes exhibit similar infection‐induced gene signatures, with the upregulation of interferon‐stimulated genes and interleukin (IL)‐6 signaling pathways. Furthermore, comparison of cDCs between patients with severe and mild disease showed severely ill patients to exhibit profound downregulation of genes encoding molecules involved in antigen presentation, such as MHCII, TAP, and costimulatory proteins, whereas we observed the opposite for proinflammatory molecules, such as complement and coagulation factors. Thus, as disease severity increases, cDC2s exhibit enhanced inflammatory properties and lose antigen presentation capacity. Moreover, DC3s showed upregulation of anti‐apoptotic genes and accumulated during infection. Direct exposure of cDC2s to the virus in vitro recapitulated the activation profile observed in vivo. Our findings suggest that SARS‐CoV‐2 interacts directly with cDC2s and implements an efficient immune escape mechanism that correlates with disease severity by downregulating crucial molecules required for T‐cell activation. This article is protected by copyright. All rights reserved

The reported clinical activity of lurbinectedin in Small Cell Lung Cancer (SCLC) prompted us to investigate the selective mechanism of this drug in SCLC cell lines. Since lurbinectedin binds the DNA minor groove modifying DNA structure, we hypothesized that it can interfere with transcription regulation. Using SHP-77 SCLC cell line, we investigated the effect of lurbinectedin on transcriptomic profile by microarray approach, at drug concentration that reduced the cell growth rate by 50%. We found only 89 differently expressed genes (DEG), 31 up- regulated and 58 down-regulated, after 6 hours of treatment whereas there was a dramatic change in gene expression profiles after 24 hours (4529 DEGs of which 1982 up-regulated and 2547 down-regulated) and 48 hours (5457 DEGs of which 2368 up-regulated and 3089 down-regulated) of exposure. Among the genes that were clearly down-regulated at both 24 and 48 hours, there was ASCL1, a gene that encodes a transcription factor required for proper development of neuronal and pulmonary neuroendocrine cells. ASCL1 regulates stemness and cell cycle progression and it is increased in high grade neuroendocrine tumours including SCLC. Western blot analysis confirmed strong reduction of the ASCL1 protein level in SHP-77 cell line. From literature data we retrieved the ChIP-Seq target genes of ASCL1 derived from different SCLC cell lines and compared them to the list of genes at basal condition in SHP-77 cell line. Then we computed Pearson correlation between the expression of ASCL1 and these targets and filtered only strong positive correlations. Through this approach, we finally selected 213 target genes of ASCL1 many of which were coherently inhibited after 24 and 48 hours of treatment. These genes were mainly involved in MAPK and Wnt signalling pathways, both crucial for SCLC. The mechanism of transcription modulation driven by ASCL1 after lurbinectedin treatment is under investigation by ChIP-Seq technology. Moreover, work is in progress to extend our findings on others SCLC cell lines and in sub-lines in which ASCL1 was silenced. We tested whether lurbinectedin shared a similar effect on transcriptomic profile as other known drugs: by dividing up and down regulated genes and testing their correlation to the drug-related gene profiles provided by the tool Enrichr, we found that lurbinectedin has a high correlation to the topoisomerase I inhibitor class. This finding deserves further experimental verifications also in view of potential clinical interest in the combination of lurbinectedin and topoisomerase I inhibitors. Citation Format: Laura Mannarino, Ilaria Craparotta, Federica Mirimao, Nicolò Panini, Monica Lupi, Giulia Protti, Roberta Frapolli, Sergio Marchini, Maurizio D'Incalci. Lurbinectedin down-regulates ASCL1 transcription factor in Small Cell Lung Cancer (SCLC) [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr LB-B13. doi:10.1158/1535-7163.TARG-19-LB-B13