Inhibition of Notch signalling has ability to alter the proximal and distal TCR signalling events in human CD3+ αβ T-cells

Differential impacts of TNFα inhibitors on the transcriptome of Th cells

BACKGROUND

Targeting TNFα is beneficial in many autoimmune and inflammatory diseases, including rheumatoid arthritis. However, the response to each of the existing TNFα inhibitors (TNFis) can be patient- and/or disease-dependent. In addition, TNFis can induce the production of type 1 interferons (IFNs), which contribute to their non-infection side effects, such as pustular psoriasis. Thus far, the molecular mechanisms mediating the drug-specific effects of TNFis and their induction of type 1 IFNs are not fully understood.

METHODS

Peripheral blood mononuclear cells (PBMCs) were collected from healthy donors and stimulated in vitro with anti-CD3 and anti-CD28 in the absence or presence of adalimumab, etanercept, or certolizumab. Th cells were isolated from the stimulated PBMCs, and their RNA was subjected to RNA-seq and quantitative polymerase chain reaction.

RESULTS

Adalimumab and etanercept, which contain Fc, but not certolizumab, which does not contain Fc, inhibited the expression of several effector cytokines by Th cells within anti-CD3/anti-CD28-stimulated PBMCs. Transcriptomic analyses further showed that adalimumab, but not certolizumab, reciprocally induced type 1 IFN signals and the expression of CD96 and SIRPG in Th cells. The unique effects of adalimumab were not due to preferential neutralization of soluble TNFα but instead were mediated by several distinct mechanisms independent or dependent of Fc-facilitated physical interaction between Th cells and CD14+ monocytes.

CONCLUSIONS

TNFis can have drug-specific effects on the transcriptional profile of Th cells.

Not Only Immune Escape-The Confusing Role of the TRP Metabolic Pathway in Carcinogenesis

BACKGROUND

The recently discovered phenomenon that cancer cells can avoid immune response has gained scientists' interest. One of the pathways involved in this process is tryptophan (TRP) metabolism through the kynurenine pathway (KP). Individual components involved in TRP conversion seem to contribute to cancerogenesis both through a direct impact on cancer cells and the modulation of immune cell functionality. Due to this fact, this pathway may serve as a target for immunotherapy and attempts are being made to create novel compounds effective in cancer treatment. However, the results obtained from clinical trials are not satisfactory, which raises questions about the exact role of KP elements in tumorigenesis. An increasing number of experiments reveal that TRP metabolites may either be tumor promoters and suppressors and this is why further research in this field is highly needed. The aim of this study is to present KP as a modulator of cancer development through multiple mechanisms and to point to its ambiguity, which may be a reason for failures in treatment based on the inhibition of tryptophan metabolism.

Notch signaling facilitates hepatitis B virus covalently closed circular DNA transcription via cAMP response element-binding protein with E3 ubiquitin ligase-modulation

Notch1 is regulated by E3 ubiquitin ligases, with proteasomal degradation of the Notch intracellular domain affecting the transcription of target genes. cAMP response element-binding protein (CREB) mediates the transcription of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA). We assessed the relationship between HBV cccDNA and Notch signaling activities. HBV cccDNA levels and relative gene expression were evaluated in HBV-replicating cells treated with Jagged1 shRNA and a γ-secretase inhibitor. The effects of these factors in surgically resected clinical samples were also assessed. Notch inhibition suppressed HBV cccDNA and CREB-related expression but increased ITCH and NUMB levels. Proteasome inhibitor augmented HBV cccDNA, restored Notch and CREB expression, and inhibited ITCH and NUMB function. Increased HBV cccDNA was observed after ITCH and NUMB blockage, even after treatment with the adenylate cyclase activator forskolin; protein kinase A (PKA) inhibitor had the opposite effect. Notch activation and E3 ligase inactivation were observed in HBV-positive cells in clinical liver tissue. Collectively, these findings reveal that Notch signaling activity facilitates HBV cccDNA transcription via CREB to trigger the downstream PKA-phospho-CREB cascade and is regulated by E3 ubiquitin ligase-modulation of the Notch intracellular domain.

The multifaceted role of Notch signal in regulating T cell fate

Notch signaling pathway facilitates important cellular functions of the host. Notch signal is essential for the development of T cells, and the role of Notch in fine tuning of αβ versus γδ T cell lineage commitment is fundamentally different in mice and human. The Notch family of cell surface receptor likewise plays a critical role in regulating T cell activation, and influences T cell response both intrinsically and through the local environment. In this review, we take an overview of Notch signaling pathway and also emphasize the role of Notch signal in T cell lineage differentiation and activating effector function of peripheral T cells.

Checkpoint Blockade Rescues the Repressive Effect of Histone Deacetylases Inhibitors on γδ T Cell Function

Histone deacetylases (HDAC) are one of the key epigenetic modifiers that control chromatin accessibility and gene expression. Their role in tumorigenesis is well established and HDAC inhibitors have emerged as an effective treatment modality. HDAC inhibitors have been investigated for their specific antitumor activities and also clinically evaluated in treatment of various malignancies. In the present study, we have investigated the effect of HDAC inhibitors on the effector functions of human γδ T cells. HDAC inhibitors inhibit the antigen-specific proliferative response of γδ T cells and cell cycle progression. In antigen-activated γδ T cells, the expression of transcription factors (Eomes and Tbet) and effector molecules (perforin and granzyme B) were decreased upon treatment with HDAC inhibitors. Treatment with HDAC inhibitors attenuated the antitumor cytotoxic potential of γδ T cells, which correlated with the enhanced expression of immune checkpoints programmed death-1 (PD-1) and programmed death ligand-1 in γδ T cells. Interestingly, PD-1 blockade improves the antitumor effector functions of HDAC inhibitor-treated γδ T cells, which is reflected in the increased expression of Granzyme B and Lamp-1. This study provides a rationale for designing HDAC inhibitor and immune check point blockade as a combinatorial treatment modality for cancer.

Effect of Notch and PARP Pathways' Inhibition in Leukemic Cells

Differentiation of blood cells is one of the most complex processes in the body. It is regulated by the action of transcription factors in time and space which creates a specific signaling network. In the hematopoietic signaling system, Notch is one of the main regulators of lymphocyte development. The aim of this study was to get insight into the regulation of Notch signalization and the influence of poly(ADP-ribose)polymerase (PARP) activity on this process in three leukemia cell lines obtained from B and T cells. PARP1 is an enzyme involved in posttranslational protein modification and chromatin structure changes. B and T leukemia cells were treated with Notch and PARP inhibitors, alone or in combination, for a prolonged period. The cells did not show cell proliferation arrest or apoptosis. Analysis of gene and protein expression set involved in Notch and PARP pathways revealed increase in JAGGED1 expression after PARP1 inhibition in B cell lines and changes in Ikaros family members in both B and T cell lines after γ-secretase inhibition. These data indicate that Notch and PARP inhibition, although not inducing differentiation in leukemia cells, induce changes in signaling circuits and chromatin modelling factors.