Expression of and immune responses to leukemia antigens in patients with hematological malignancies

Leukemia cells are characterized by differentially expressed leukemia-associated antigens (LAAs). We wondered whether the expression of the LAAs WT1 and RHAMM as well as the T cellular immune response to these LAAs correlated with the clinical outcome of patients suffering from leukemia. We investigated the expression of WT1 and RHAMM at RNA level using qPCR before and after treatment. We concluded that WT1 is a suitable marker for MRD after allogeneic SCT and that a WT1-specific T cell response might contribute to the maintenance of CR

Block of death-receptor apoptosis protects mouse cytomegalovirus from macrophages and is a determinant of virulence in immunodeficient hosts.

The inhibition of death-receptor apoptosis is a conserved viral function. The murine cytomegalovirus (MCMV) gene M36 is a sequence and functional homologue of the human cytomegalovirus gene UL36, and it encodes an inhibitor of apoptosis that binds to caspase-8, blocks downstream signaling and thus contributes to viral fitness in macrophages and in vivo. Here we show a direct link between the inability of mutants lacking the M36 gene (ΔM36) to inhibit apoptosis, poor viral growth in macrophage cell cultures and viral in vivo fitness and virulence. ΔM36 grew poorly in RAG1 knockout mice and in RAG/IL-2-receptor common gamma chain double knockout mice (RAGγC(-/-)), but the depletion of macrophages in either mouse strain rescued the growth of ΔM36 to almost wild-type levels. This was consistent with the observation that activated macrophages were sufficient to impair ΔM36 growth in vitro. Namely, spiking fibroblast cell cultures with activated macrophages had a suppressive effect on ΔM36 growth, which could be reverted by z-VAD-fmk, a chemical apoptosis inhibitor. TNFα from activated macrophages synergized with IFNγ in target cells to inhibit ΔM36 growth. Hence, our data show that poor ΔM36 growth in macrophages does not reflect a defect in tropism, but rather a defect in the suppression of antiviral mediators secreted by macrophages. To the best of our knowledge, this shows for the first time an immune evasion mechanism that protects MCMV selectively from the antiviral activity of macrophages, and thus critically contributes to viral pathogenicity in the immunocompromised host devoid of the adaptive immune system

New Insights on CD8+ T Cells in Inflammatory Bowel Disease and Therapeutic Approaches

CD8+ T cells are involved in the pathogenesis of inflammatory bowel disease (IBD), a complex multifactorial chronic disease. Here, we present an overview of the current research with the controversial findings of CD8+ T cell subsets and discuss some possible perspectives on their therapeutic value in IBD. Studies on the role of CD8+ T cells in IBD have contradictory outcomes, which might be related to the heterogeneity of the cells. Recent data suggest that cytotoxic CD8+ T cells (Tc1) and interleukin (IL) 17-producing CD8+ (Tc17) cells contribute to the pathogenesis of IBD. Moreover, subsets of regulatory CD8+ T cells are abundant at sites of inflammation and can exhibit pro-inflammatory features. Some subsets of tissue resident memory CD8+ T cells (Trm) might be immunosuppressant, whereas others might be pro-inflammatory. Lastly, exhausted T cells might indicate a positive outcome for patients. The function and plasticity of different subsets of CD8+ T cells in health and IBD remain to be further investigated in a challenging field due to the limited availability of mucosal samples and adequate controls.</jats:p

Beeinflussung des Zusammenspiels zwischen Melanom und Immunzellen durch Reprogrammierung des Tumorsekretoms; Schlussbericht zu Teilprojekt 1 des Verbundvorhabens: MelAutim - Systemmedizinische Untersuchung des Melanoms und der Autoimmunität im Kontext von Immuntherapien

In TP1 haben wir untersucht, wie Melanomzellen durch ihr Sekretom Immunzellen beeinflussen und dadurch die Tumorprogression, Immuntherapie-Resistenz sowie ein Aufflammen vorbestehender Autoimmunerkrankungen (AE) ermöglichen. Der Fokus lag dabei auf den durch den Transkriptionsfaktor E2F1 in Tumorzellen induzierten immunmodulatorischen Eigenschaften des Melanom-Sekretoms. Weil E2F1 seine prometastatische Funktion über Interaktionen mit einem wachsenden Repertoire an transkriptionellen Koregulatoren ausübt, sollten weiterhin die Kofaktoren gefunden werden, die die transkriptionelle Aktivität von E2F1 auf Zielgene mit immunmodulatorischen Funktionen lenken. Schließlich sollten die identifizierten E2F1/Kofaktor/Zielgen-Achsen, die das Sekretom zur Deregulierung der Immunantwort und zugunsten der Krebsprogression kontrollieren, anhand spezifischer Inhibitor-Wirkstoffe reprogrammiert werden

CD8+ T Cell Subsets as Biomarkers for Predicting Checkpoint Therapy Outcomes in Cancer Immunotherapy

The advent of immune checkpoint blockade (ICB) has transformed cancer immunotherapy, enabling remarkable long-term outcomes and improved survival, particularly with ICB combination treatments. However, clinical benefits remain confined to a subset of patients, and life-threatening immune-related adverse effects pose a significant challenge. This limited efficacy is attributed to cancer heterogeneity, which is mediated by ligand&ndash;receptor interactions, exosomes, secreted factors, and key transcription factors. Oncogenic regulators like E2F1 and MYC drive metastatic tumor environments and intertwine with immunoregulatory pathways, impairing T cell function and reducing immunotherapy effectiveness. To address these challenges, FDA-approved biomarkers, such as tumor mutational burden (TMB) and programmed cell death-ligand 1 (PD-L1) expression, help to identify patients most likely to benefit from ICB. Yet, current biomarkers have limitations, making treatment decisions difficult. Recently, T cells&mdash;the primary target of ICB&mdash;have emerged as promising biomarkers. This review explores the relationship between cancer drivers and immune response, and emphasizes the role of CD8+ T cells in predicting and monitoring ICB efficacy. Tumor-infiltrating CD8+ T cells correlate with positive clinical outcomes in many cancers, yet obtaining tumor tissue remains complex, limiting its practical use. Conversely, circulating T cell subsets are more accessible and have shown promise as predictive biomarkers. Specifically, memory and progenitor exhausted T cells are associated with favorable immunotherapy responses, while terminally exhausted T cells negatively correlate with ICB efficacy. Ultimately, combining biomarkers enhances predictive accuracy, as demonstrated by integrating TMB/PD-L1 expression with CD8+ T cell frequency. Computational models incorporating cancer and immune signatures could further refine patient stratification, advancing personalized immunotherapy

Apoptosis of primary MEF cells inhibits ΔM36 growth.

<p>(A) MEF cells and MEF preparations depleted of CD11b positive cells (MEF ΔCD11b) were infected with indicated virus at a MOI of 1, and 24 hours later analyzed for the induction of the active isoform of caspase-3 by flow cytometry. The percentage of caspase-3 positive cells in a representative experiment is indicated. (B) MEF or NIH-3T3 cells were infected at a MOI of 0.03 with ΔM36 (white bars) or M36rev (grey bars) and supernatants were titrated for infectious MCMV titer at day 4 post infection. Where indicated, Zymosan (30 µg/ml) and/or IFNγ (100 ng/ml) were added to the supernatant immediately following infection. Histograms indicate means from three experiments, error bars are standard deviations. (C) MEF cells were infected at a MOI of 5 with ΔM36, M36rev or mock-infected. Where indicated, IFNγ (100 ng/ml) and Zymosan (30 µg/ml) were added to the supernatant immediately following infection. Expression of the active isoform of caspase-3 was measured 24 hours post infection by flow cytometry and the percentage of caspase-3 positive cells in the total cell pool is indicated. (D) MEF cells were infected at a MOI of 0.03 with ΔM36 (white bars) or M36rev (grey bars) and supernatants were titrated for infectious MCMV at day 4 post infection. Where indicated, z-VAD-fmk (33 µM), Zymosan (30 µg/ml) and IFNγ (100 ng/ml) were added to the supernatant immediately following infection. Histograms indicate means from three experiments, error bars are standard deviations, * p<0.05.</p

Diagram of the proposed mechanism of action.

<p>Activated macrophages secrete TNFα (and possibly additional cytokines) which synergize with IFNγ in fibroblasts to block virus growth by a mechanism that is dependent on caspase signaling. M36 blocks the caspase-dependent signaling pathway and thus prevents apoptosis and rescues the virus growth.</p

Macrophage, but not NK cell, depletion rescues ΔM36 MCMV <i>in vivo</i>.

<p>In a combined experiment to elucidate the role of (A) NK cells and (B) macrophages in the control of ΔM36 MCMV growth, RAG1^−/− and RAGγC^−/− mice received injections of 200 µl liposome encapsulated (A) PBS or (B) clodronate 48 hours (i.v.) and 24 hours (i.p.) prior to viral infection. Following liposome injection mice were i.p. injected with 10⁵ PFU ΔM36 (○) or M36rev (•) MCMV (n = 4–5/group). At day 3 post infection infectious virus was determined by plaque assay on MEF cells in spleen (top panels), lungs (middle panels) and liver (bottom panels). Each symbol represents an individual mouse. Differences in median values are highlighted by grey shading. The dashed line shows the limit of detection. *p<0.05; **p<0.01.</p

TNFα secreted from macrophages synergizes with IFNγ to impair ΔM36 growth by a caspase-dependent mechanism.

<p>(A) Experimental setup: ANA-I cells were treated for 5 days with Zymosan and IFNγ in the presence of ΔM36 MCMV, M36rev MCMV, or no virus, upon which the supernatants were filtered to prevent virus carryover and transferred to CD11b-depleted MEF cells infected with ΔM36 or M36rev. (B) Infectious titer of ΔM36 (white bars) or M36rev-MCMV (grey bars) at 5 days post infection. Legends below the x-axis indicate the medium used during infection – control medium (DMEM), supernatant from ANA-I cells infected with ΔM36, M36rev or no virus (MOCK). Where indicated, the ANA-I supernatant was supplemented with neutralizing anti-TNFα (1 µg/ml) antibodies or z-VAD-fmk (33 µM). Histograms indicate mean values from three separate experiments, error bars show SD, * p<0.05.</p