Successful translation of chimeric antigen receptor (CAR) T cell therapy for the treatment of solid tumors has proved to be troublesome, mainly due to the complex tumor microenvironment promoting T cell dysfunction and antigen heterogeneity. Mesothelin (MSLN) has emerged as an attractive target for CAR T cell therapy of several solid malignancies, including ovarian cancer. To improve clinical response rates with MSLN-CAR T cells, a better understanding of the mechanisms impacting CAR T cell functionality in vitro is crucial. Here, we demonstrated superior cytolytic capacity of CD28-costimulated MSLN-CAR T cells (M28z) relative to 4–1BB-costimulated MSLN-CAR T cells (MBBz). Furthermore, CD28-costimulated MSLN CAR T cells displayed enhanced cytolytic capacity against tumor spheroids with heterogeneous MSLN expression compared to MBBz CAR T cells. In this study, we identified CAR-mediated trogocytosis as a potential impeding factor for successful MSLN-CAR T cell therapy due to fratricide killing and contributing to tumor antigen heterogeneity. Moreover, we link antigen-dependent upregulation of LAG-3 with reduced CAR T cell functionality. Taken together, our study highlights the therapeutic potential and bottlenecks of MSLN-CAR T cells, providing a rationale for combinatorial treatment strategies.

Lipids play a major role in inflammatory diseases by altering inflammatory cell functions, either through their function as energy substrates or as lipid mediators such as oxylipins. Autophagy, a lysosomal degradation pathway that limits inflammation, is known to impact on lipid availability, however, whether this controls inflammation remains unexplored. We found that upon intestinal inflammation visceral adipocytes upregulate autophagy and that adipocyte-specific loss of the autophagy gene Atg7 exacerbates inflammation. While autophagy decreased lipolytic release of free fatty acids, loss of the major lipolytic enzyme Pnpla2/Atgl in adipocytes did not alter intestinal inflammation, ruling out free fatty acids as anti-inflammatory energy substrates. Instead, Atg7deficient adipose tissues exhibited an oxylipin imbalance, driven through an NRF2-mediated upregulation of Ephx1. This shift reduced secretion of IL-10 from adipose tissues, which was dependent on the cytochrome P450-EPHX pathway, and lowered circulating levels of IL-10 to exacerbate intestinal inflammation. These results suggest an underappreciated fat-gut crosstalk through an autophagy-dependent regulation of anti-inflammatory oxylipins via the cytochrome P450-EPHX pathway, indicating a protective effect of adipose tissues for distant inflammation.

Autophagy is a critical cellular recycling pathway which is genetically linked to the development of intestinal inflammation in humans. Inflammation drives adipose tissue breakdown and provision of major nutrients such as free fatty acids (FFA). However, the effect of autophagy-mediated FFA release by adipocytes in immune-mediated inflammatory diseases remains unexplored. In a mouse model of intestinal inflammation, we found that visceral adipocytes upregulate autophagy at peak inflammation. Adipocyte-specific loss of the key autophagy gene Atg7 (Atg7Ad) resulted in the exacerbation of intestinal inflammation. TNFα-induced lipolysis was impaired in Atg7-deficient adipocytes leading to the reduced availability of several FFA species, and decreased expression of the FFA transporter CD36 on adipose tissue macrophages (ATMs). Visceral adipose tissues from Atg7Ad mice released less IL-10 resulting in lower levels of circulating IL-10 in colitis. ATMs present the main source of adipose tissue-derived IL-10 during colitis. In vitro assays confirmed that FFA restriction from macrophages reduced CD36 expression and diminished IL-10 production. Taken together, our study demonstrates that autophagy-mediated FFA release from adipocytes directs anti-inflammatory responses in ATMs, which in turn conveys protective effects for distant intestinal inflammation.

Fibrillar collagen deposition, stiffness, and downstream signalling support the development of leiomyomas (LM), common benign mesenchymal tumours of the uterus, and are associated with aggressiveness in multiple carcinomas. Compared to epithelial carcinomas, however, the impact of fibrillar collagens on malignant mesenchymal tumours, including uterine leiomyosarcoma (LMS), remains elusive. In this study, we analyse the network morphology and density of fibrillar collagens combined with the gene expression of LMS, LM and normal myometrium (MM). We find that, in contrast to LM, LMS tumours present low collagen density and increased expression of collagen-remodelling genes, features associated with tumour aggressiveness. Using collagen-based 3D matrices, we show that the activity of MMP14, a central protein with collagen-remodelling functions particularly overexpressed in LMS, is necessary for LMS cell proliferation. In addition, we find that, unlike MM and LM cells, LMS proliferation and migration are not affected by collagen substrate stiffness. We demonstrate that LMS cell growth in low matrix adhesion microenvironments is supported by an enhanced basal YAP activity. Altogether, our results indicate that LMS cells acquire high collagen remodelling capabilities and are adapted to grow and migrate in low collagen and soft microenvironments. These results further suggest that matrix remodelling and YAP are potential therapeutic targets for this deadly disease.

The expression, abundance, and microarchitecture of fibrillar collagens are associated with tumor development and aggressiveness in various carcinomas. However, the impact of fibrillar collagens on mesenchymal tumors is less understood. While uterine leiomyomas, also known as fibroids, are characterized by high fibrillar collagen deposition and depend on ECM signaling for cell proliferation, the impact of fibrillar collagens on malignant uterine leiomyosarcomas has not been explored. Thus, identifying malignancy and aggressiveness-associated features of the fibrillar collagen-leiomyosarcoma crosstalk may provide novel biomarkers and therapeutic targets for these aggressive tumors. We used publicly available RNAseq data and performed RNAseq and picrosirius red analysis of fiber microarchitecture in a cohort of normal myometrium (MM; n =68 ), leiomyoma (LM; n = 66), and leiomyosarcoma (LMS; n = 67) tissues. Furthermore, we cultured patient-derived primary cells (4 MM, 3 LM, and 4 LMS) on collagen I-functionalized polyacrylamide gels at stiffness ranging from 0.5 to 115 kPa, covering the physiological and pathological stiffness, to investigate distinct behaviors between cell types, including proliferation, migration, and activity of the ECM stiffness molecular rheostat YAP/TAZ. At the protein level, analysis of fibrillar collagen microarchitecture revealed that LMS tumors present reduced fibrillar collagen density and hyphal growth units and enhanced fiber endpoints compared to both MM and LM. At the gene expression level, however, LMS tumors did not show reduced fibrillar collagen expression, instead they exhibited enhanced matrix metalloproteinase expression, particularly of MMP14. Furthermore, COL11A1 was specifically upregulated in LMS tumors and its expression was associated with poor prognosis. Finally, in vitro response of MM, LM, and LMS cells to collagen I at defined stiffness showed that LMS cell migration, proliferation, and subcellular localization of YAP/TAZ are less sensitive to substrate stiffness than in MM and LM cells, although the response varied between distinct donors. In conclusion, we show that LMS tumors typically present low fibrillar collagen protein expression likely due to enhanced degradation. In addition, collagen I adhesion and stiffness have a lower impact on malignant LMS cells than on MM and LM, which may explain their ability to grow in low-collagen microenvironments. Furthermore, this study shows that COL11A1 is a potential biomarker with prognostic value in leiomyosarcoma. Citation Format: Jordi Gonzalez-Molina, Paula Hahn, Raul Maia Falcão, Georgia Kokaraki, Jorge Estefano de Souza, Tirzah Braz Petta Lajus, Kaisa Lehti, Joseph W. Carlson. The microarchitecture and fibrillar collagen expression of leiomyosarcoma are associated with malignancy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6096.