TCR signalling in response to affinity stimulation

T cells are an essential part of the adaptive immune system and protect the body from intracellular infections. The specificity with which αßTCR-bearing T cells recognize cognate antigen presented on MHC molecules is paramount to maintaining the balance between mounting effector functions against pathogens and establishing peripheral tolerance to self. The mechanism by which T cells translate qualitative differences in TCR:pMHC binding to sensitive proximal signalling events which ultimately result in specific Tcell effector responses to infected cells but not to self is mostly unknown.To address how T cell signalling responds to qualitative differences in TCR triggering by pMHC, I established a system of stimulating T cells bearing the 1G4 TCR specifically in vitro with a panel of four NY-ESO-1156-165 peptide variant MHC tetramers. Single amino acid substitutions to the NY-ESO-1156-165 peptide conferred a maximum 35-fold difference in the monomeric affinity for the 1G4 TCR. The system allows the highly controlled investigation of very rapid TCR proximal signalling events simultaneously and quantitatively using flow cytometry. Stimulations with pMHC tetramers showed rapid sensitive sequential signalling responses which were able to confer ligand discrimination. Very early signalling events such as CD3ζ phosphorylation showed analogue responses to the different affinity pMHC tetramers. Later signalling events including phospho-ERK showed a distinct on/off switch-like response. The amplitude of the very early analogue signalling responses determined the extent of later digital ERK signals. This indicates that a certain analogue signalling threshold must be passed to result in T cell activation.The thymocyte protein Themis has been shown proximal TCR signalling to modulate thymocyte selection thresholds. Its deletion results in profound defects in positive thymocyte selection. Themis locates to the LAT signalosome of the TCR signalling cascade via Grb2, yet its molecular function is unknown. Employing the system I established, I demonstrate that Themis-k/d cells show increased levels of CD3z-chain phosphorylation, phospho-ERK signalling and signal-induced apoptosis which was independent of the ERK signal. This shows that Themis is a global attenuator of proximal TCR signalling. We are currently investigating possible associations of Themis to proteins phosphastases such as SHP-1 which could attenuate TCR proximal protein tyrosine signalling events.This thesis is not currently available via ORA

TCR signalling in response to affinity stimulation

T cells are an essential part of the adaptive immune system and protect the body from intracellular infections. The specificity with which αßTCR-bearing T cells recognize cognate antigen presented on MHC molecules is paramount to maintaining the balance between mounting effector functions against pathogens and establishing peripheral tolerance to self. The mechanism by which T cells translate qualitative differences in TCR:pMHC binding to sensitive proximal signalling events which ultimately result in specific Tcell effector responses to infected cells but not to self is mostly unknown.To address how T cell signalling responds to qualitative differences in TCR triggering by pMHC, I established a system of stimulating T cells bearing the 1G4 TCR specifically in vitro with a panel of four NY-ESO-1156-165 peptide variant MHC tetramers. Single amino acid substitutions to the NY-ESO-1156-165 peptide conferred a maximum 35-fold difference in the monomeric affinity for the 1G4 TCR. The system allows the highly controlled investigation of very rapid TCR proximal signalling events simultaneously and quantitatively using flow cytometry. Stimulations with pMHC tetramers showed rapid sensitive sequential signalling responses which were able to confer ligand discrimination. Very early signalling events such as CD3ζ phosphorylation showed analogue responses to the different affinity pMHC tetramers. Later signalling events including phospho-ERK showed a distinct on/off switch-like response. The amplitude of the very early analogue signalling responses determined the extent of later digital ERK signals. This indicates that a certain analogue signalling threshold must be passed to result in T cell activation.The thymocyte protein Themis has been shown proximal TCR signalling to modulate thymocyte selection thresholds. Its deletion results in profound defects in positive thymocyte selection. Themis locates to the LAT signalosome of the TCR signalling cascade via Grb2, yet its molecular function is unknown. Employing the system I established, I demonstrate that Themis-k/d cells show increased levels of CD3z-chain phosphorylation, phospho-ERK signalling and signal-induced apoptosis which was independent of the ERK signal. This shows that Themis is a global attenuator of proximal TCR signalling. We are currently investigating possible associations of Themis to proteins phosphastases such as SHP-1 which could attenuate TCR proximal protein tyrosine signalling events.</p

Recurrent High Grade Serous Ovarian Cancer Management

Despite an aggressive treatment strategy for high grade serous ovarian cancer (HGSOC) that incorporates cytoreduction, platinum compounds, anti-angiogenic agents, and poly (ADP-ribose) polymerase (PARP) inhibitors, most patients, especially those who are with stage III-IV HGSOC, will relapse. The management of recurrent HGSOC is a challenging issue faced by gyneco-oncologists and medical oncologists in clinical practice. This chapter provides an overview of the current optimal management of recurrent HGSOC. First, recurrence is classified based on the time of onset. This is followed by a discussion on the place of surgery within the treatment strategy. Finally, the role of systemic treatments (chemotherapy, targeted agents, and immunotherapy) in the management of HGSOC are presented

MDSC in Mice and Men: Mechanisms of Immunosuppression in Cancer.

Myeloid-derived suppressor cells (MDSCs) expand during pathological conditions in both humans and mice and their presence is linked to poor clinical outcomes for cancer patients. Studying MDSC immunosuppression is restricted by MDSCs' rarity, short lifespan, heterogeneity, poor viability after freezing and the lack of MDSC-specific markers. In this review, we will compare identification and isolation strategies for human and murine MDSCs. We will also assess what direct and indirect immunosuppressive mechanisms have been attributed to MDSCs. While some immunosuppressive mechanisms are well-documented in mice, e.g., generation of ROS, direct evidence is still lacking in humans. In future, bulk or single-cell genomics could elucidate which phenotypic and functional phenotypes MDSCs adopt in particular microenvironments and help to identify potential targets for therapy

Immunosuppressive low-density neutrophils in the blood of cancer patients display a mature phenotype

The presence of human neutrophils in the tumor microenvironment is strongly correlated to poor overall survival. Most previous studies have focused on the immunosuppressive capacities of low-density neutrophils (LDN), also referred to as granulocytic myeloid-derived suppressor cells, which are elevated in number in the blood of many cancer patients. We observed two types of LDN in the blood of lung cancer and ovarian carcinoma patients: CD45high LDN, which suppressed T-cell proliferation and displayed mature morphology, and CD45low LDN, which were immature and non-suppressive. We simultaneously evaluated the classical normal-density neutrophils (NDN) and, when available, tumor-associated neutrophils. We observed that NDN from cancer patients suppressed T-cell proliferation, and NDN from healthy donors did not, despite few transcriptomic differences. Hence, the immunosuppression mediated by neutrophils in the blood of cancer patients is not dependent on the cells’ density but rather on their maturity

How to measure the immunosuppressive activity of MDSC: assays, problems and potential solutions

Myeloid-derived suppressor cells (MDSC) are a heterogeneous group of mononuclear and polymorphonuclear myeloid cells, which are present at very low numbers in healthy subjects, but can expand substantially under disease conditions. Depending on disease type and stage, MDSC comprise varying amounts of immature and mature differentiation stages of myeloid cells. Validated unique phenotypic markers for MDSC are still lacking. Therefore, the functional analysis of these cells is of central importance for their identification and characterization. Various disease-promoting and immunosuppressive functions of MDSC are reported in the literature. Among those, the capacity to modulate the activity of T cells is by far the most often used and best-established read-out system. In this review, we critically evaluate the assays available for the functional analysis of human and murine MDSC under in vitro and in vivo conditions. We also discuss critical issues and controls associated with those assays. We aim at providing suggestions and recommendations useful for the contemporary biological characterization of MDSC

Identification of an Immature Subset of PMN-MDSC Correlated to Response to Checkpoint Inhibitor Therapy in Patients with Metastatic Melanoma.

PMN-MDSCs support tumor progression and resistance to ICI therapy through their suppressive functions but their heterogeneity limits their use as biomarkers in cancer. Our aim was to investigate the phenotypic and functional subsets of PMN-MDSCs to identify biomarkers of response to ICI therapy. We isolated low-density CD15 PMNs from patients with metastatic melanoma and assessed their immune-suppressive capacities. Expression of CD10 and CD16 was used to identify mature and immature subsets and correlate them to inhibition of T cell proliferation or direct cytotoxicity. Frequencies of the PMN-MDSCs subsets were next correlated to the radiological response of 36 patients receiving ICI therapy. Mature activated cells constituted the major population of PMN-MDSCs. They were found in a higher proportion in the pre-treatment blood of patients non responders to ICI. A subset of immature cells characterized by intermediate levels of CD10 and CD16, the absence of expression of SIRPα and a strong direct cytotoxicity to T cells was increased in patients responding to ICI. The paradoxical expansion of such cells during ICI therapy suggests a role of PMNs in the inflammatory events associated to efficient ICI therapy and the usefulness of their monitoring in patients care

Centralizing surgery for ovarian cancer in a ‘non-centralizing’ country (Belgium): the UNGO (UCLouvain Network of Gynaecological Oncology) experience

Objective In Belgium there is no centralization of surgery for ovarian cancer, with more than 100 centers treating around 800 cases per year. In 2017 a network with several collaborating hospitals was established to centralize surgery for ovarian cancer (UCLouvain Network of Gynecological Oncology; UNGO) following publication of the European Society of Gynecological Oncology (ESGO) recommendations and quality criteria for surgery of advanced ovarian cancer. We obtained ESGO accreditation in 2019. Methods We retrospectively collected data associated with patients undergoing surgery in our institution from 2007 to 2016, before the creation of the network (cohort 1) and, following the establishment of UNGO (2017–2021), patients undergoing surgery were prospectively registered in a REDCap database (cohort 2). The outcomes of the two cohorts were compared. Results A total of 314 patients underwent surgery in our institution from 2007 and 2021: 7.5 patients/year in cohort 1 (retrospective, 2007–2016) and 40.8 patients/year in cohort 2 (after network creation, 2017–2021). Median disease-free survival was increased from 16.5 months (range 13.2–20.4) in cohort 1 to 27.1 months (range 21.5–33.2) in cohort 2 (p=0.0004). In cohort 2, the rate of patients with residual disease at the end of the surgery was significantly less (18.7% vs 8.8%, p=0.023), although more patients in cohort 1 received neoadjuvant chemotherapy (89% vs 54%, p<0.001). However, there was a higher rate of complications in the patients in cohort 2 (18.8% vs 30%, p=0.041). Conclusion Our study shows that, with the help of ESGO and its recommendations, we have been able to create an efficient advanced ovarian cancer centralized network and this may provide an improvement in the quality of care

Extracellular galectins as controllers of cytokines in hematological cancer

Galectins and cytokines are both secreted proteins whose levels are prognosis factors for several cancers. Extracellular galectins bind to the glycans decorating glycoproteins and are overproduced in most cancers. Accumulative evidence shows that galectins regulate cytokines during cancer progression. While galectins alter cytokine function by binding to the glycans decorating cytokines or their receptors, cytokines could also regulate galectin expression and function. This review revises these complex interactions and their clinical impact, particularly in hematological cancers