Hematopoietic versus Solid Cancers and T Cell Dysfunction: Looking for Similarities and Distinctions

Cancer cells escape, suppress and exploit the host immune system to sustain themselves, and the tumor microenvironment (TME) actively dampens T cell function by various mechanisms. Over the last years, new immunotherapeutic approaches, such as adoptive chimeric antigen receptor (CAR) T cell therapy and immune checkpoint inhibitors, have been successfully applied for refractory malignancies that could only be treated in a palliative manner previously. Engaging the anti-tumor activity of the immune system, including CAR T cell therapy to target the CD19 B cell antigen, proved to be effective in acute lymphocytic leukemia. In low-grade hematopoietic B cell malignancies, such as chronic lymphocytic leukemia, clinical outcomes have been tempered by cancer-induced T cell dysfunction characterized in part by a state of metabolic lethargy. In multiple myeloma, novel antigens such as BCMA and CD38 are being explored for CAR T cells. In solid cancers, T cell-based immunotherapies have been applied successfully to melanoma and lung cancers, whereas application in e.g., breast cancer lags behind and is modestly effective as yet. The main hurdles for CAR T cell immunotherapy in solid tumors are the lack of suitable antigens, anatomical inaccessibility, and T cell anergy due to immunosuppressive TME. Given the wide range of success and failure of immunotherapies in various cancer types, it is crucial to comprehend the underlying similarities and distinctions in T cell dysfunction. Hence, this review aims at comparing selected, distinct B cell-derived versus solid cancer types and at describing means by which malignant cells and TME might dampen T cell anti-tumor activity, with special focus on immunometabolism. Drawing a meaningful parallel between the efficacy of immunotherapy and the extent of T cell dysfunction will shed light on areas where we can improve immune function to battle cancer

Expression of the alpha subunit of PABA peptide hydrolase (EC 3.4.24.18) in MDCK cells Synthesis and secretion of an enzymatically inactive homodimer

AbstractIn this paper, we report the expression of PPHα in the polarized cell line MDCK (Madin Darby canine kidney). In these cells, the enzyme was synthesized m an inactive profonn, which upon treatment with trypsin was activated. The enzyme isolated from cell extracts was core-glycosylated and appeared to be retained in the ER as a homodimer. No PPHα was detectable on the surface of intact cells by immunofluoreseence. However, a complex glycosylated soluble but inactive form was present in the culture medium, suggesting that proteolytic removal of the C-terminal membrane anchoring peptide leads to the secretion of PPHα

The Noxa/Mcl-1 Axis Regulates Susceptibility to Apoptosis under Glucose Limitation in Dividing T Cells

SummaryThroughout lymphocyte development, cellular persistence and expansion are tightly regulated by survival and apoptosis. Within the Bcl-2 family, distinct apoptogenic BH3-only members like Bid, Bim, and Puma appear to function in specific cell death pathways. We found that naive human T cells after mitogenic activation, apart from expected protective Bcl-2 members, also rapidly upregulate the BH3-only protein Noxa in a p53-independent fashion. The specific role of Noxa became apparent during glucose limitation and involves interaction with the labile Bcl-2 homolog Mcl-1. Knockdown of Noxa or Mcl-1 results in protection or susceptibility, respectively, to apoptosis induced by glucose deprivation. Declining Mcl-1 levels and apoptosis induction are inversely correlated to Noxa levels and prevented by readdition of glucose. We propose that the Noxa/Mcl-1 axis is an apoptosis rheostat in dividing cells, in a selective pathway that functions to restrain lymphocyte expansion and can be triggered by glucose deprivation

Modulation of Contact System Proteases by Glycosaminoglycans SELECTIVE ENHANCEMENT OF THE INHIBITION OF FACTOR XIa

Abstract We investigated the influence of dextran sulfate, heparin, heparan sulfate, and dermatan sulfate on the inhibition of FXIa (where FXIa is activated factor XI, for example), FXIIa, and kallikrein by C1 inhibitor, α1-antitrypsin, α2-antiplasmin, and antithrombin III. The second-order rate constants for the inhibition of FXIa by C1 inhibitor, α1-antitrypsin, α2-antiplasmin, and antithrombin III, in the absence of glycosaminoglycans, were 1.8, 0.1, 0.43, and 0.32 × 103 M−1 s−1, respectively. The rate constants of the inactivation of FXIa by C1 inhibitor and by antithrombin III increased up to 117-fold in the presence of glycosaminoglycans. These data predicted that considering the plasma concentration of the inhibitors, C1 inhibitor would be the main inhibitor of FXIa in plasma in the presence of glycosaminoglycans. Results of experiments in which the formation of complexes between serine protease inhibitors and FXIa was studied in plasma agreed with this prediction. Glycosaminoglycans did not enhance the inhibition of α-FXIIa, β-FXIIa, or kallikrein by C1 inhibitor. Thus, physiological glycosaminoglycans selectively enhance inhibition of FXIa without affecting the activity of FXIIa and kallikrein, suggesting that glycosaminoglycans may modulate the biological effects of contact activation, by inhibiting intrinsic coagulation without affecting the fibrinolytic potential of FXIIa/kallikrein

Starvation and antimetabolic therapy promote cytokine release and recruitment of immune cells

Cellular starvation is typically a consequence of tissue injury that disrupts the local blood supply but can also occur where cell populations outgrow the local vasculature, as observed in solid tumors. Cells react to nutrient deprivation by adapting their metabolism, or, if starvation is prolonged, it can result in cell death. Cell starvation also triggers adaptive responses, like angiogenesis, that promote tissue reorganization and repair, but other adaptive responses and their mediators are still poorly characterized. To explore this issue, we analyzed secretomes from glucose-deprived cells, which revealed up-regulation of multiple cytokines and chemokines, including IL-6 and IL-8, in response to starvation stress. Starvation-induced cytokines were cell type-dependent, and they were also released from primary epithelial cells. Most cytokines were up-regulated in a manner dependent on NF-κB and the transcription factor of the integrated stress response ATF4, which bound directly to the IL-8 promoter. Furthermore, glutamine deprivation, as well as the antimetabolic drugs 2-deoxyglucose and metformin, also promoted the release of IL-6 and IL-8. Finally, some of the factors released from starved cells induced chemotaxis of B cells, macrophages, and neutrophils, suggesting that nutrient deprivation in the tumor environment can serve as an initiator of tumor inflammation

TRAIL receptors promote constitutive and inducible IL-8 secretion in non-small cell lung carcinoma

Interleukin-8 (IL-8/CXCL8) is a pro-angiogenic and pro-inflammatory chemokine that plays a role in cancer development. Non-small cell lung carcinoma (NSCLC) produces high amounts of IL-8, which is associated with poor prognosis and resistance to chemo-radio and immunotherapy. However, the signaling pathways that lead to IL-8 production in NSCLC are unresolved. Here, we show that expression and release of IL-8 are regulated autonomously by TRAIL death receptors in several squamous and adenocarcinoma NSCLC cell lines. NSCLC constitutively secrete IL-8, which could be further enhanced by glucose withdrawal or by treatment with TRAIL or TNF alpha. In A549 cells, constitutive and inducible IL-8 production was dependent on NF-kappa B and MEK/ERK MAP Kinases. DR4 and DR5, known regulators of these signaling pathways, participated in constitutive and glucose deprivation-induced IL-8 secretion. These receptors were mainly located intracellularly. While DR4 signaled through the NF-kappa B pathway, DR4 and DR5 both regulated the ERK-MAPK and Akt pathways. FADD, caspase-8, RIPK1, and TRADD also regulated IL-8. Analysis of mRNA expression data from patients indicated that IL-8 transcripts correlated with TRAIL, DR4, and DR5 expression levels. Furthermore, TRAIL receptor expression levels also correlated with markers of angiogenesis and neutrophil infiltration in lung squamous carcinoma and adenocarcinoma. Collectively, these data suggest that TRAIL receptor signaling contributes to a pro-tumorigenic inflammatory signature associated with NSCLC

JAK‐STAT signaling shapes the NF‐κB response in CLL towards venetoclax sensitivity or resistance via Bcl‐XL

Preventing or overcoming resistance to the Bcl-2 inhibitor venetoclax is an emerging unmet clinical need in patients with chronic lymphocytic leukemia (CLL). The upregulation of anti-apoptotic Bcl-2 members through signaling pathways within the tumor microenvironment appears as a major factor leading to resistance to venetoclax. Previously, we reported that T cells can drive resistance through CD40 and non-canonical NF-κB activation and subsequent Bcl-XL induction. Moreover, the T cell-derived cytokines IL-21 and IL-4 differentially affect Bcl-XL expression and sensitivity to venetoclax via unknown mechanisms. Here, we mechanistically dissected how Bcl-XL is regulated in the context of JAK-STAT signaling in primary CLL. First, we demonstrated a clear antagonistic role of IL-21/STAT3 signaling in the NF-κB-mediated expression of Bcl-XL, whereas IL-4/STAT6 further promoted the expression of Bcl-XL. In comparison, Bfl-1, another NF-κB target, was not differentially affected by either cytokine. Second, STAT3 and STAT6 affected Bcl-XL transcription by binding to its promoter without disrupting the DNA-binding activity of NF-κB. Third, in situ proximity ligation assays (isPLAs) indicated crosstalk between JAK-STAT signaling and NF-κB, in which STAT3 inhibited canonical NF-κB by accelerating nuclear export, and STAT6 promoted non-canonical NF-κB. Finally, NF-κB inducing kinase (NIK) inhibition interrupted the NF-κB/STAT crosstalk and re-sensitized CLL cells to venetoclax. In conclusion, we uncovered distinct crosstalk mechanisms that shape the NF-κB response in CLL towards venetoclax sensitivity or resistance via Bcl-XL, thereby revealing new potential therapeutic targets

B-cell targeting with anti-CD38 daratumumab:implications for differentiation and memory responses

B cell–targeted therapies, such as CD20-targeting mAbs, deplete B cells but do not target the autoantibody-producing plasma cells (PCs). PC-targeting therapies such as daratumumab (anti-CD38) form an attractive approach to treat PC-mediated diseases. CD38 possesses enzymatic and receptor capabilities, which may impact a range of cellular processes including proliferation and differentiation. However, very little is known whether and how CD38 targeting affects B-cell differentiation, in particular for humans beyond cancer settings. Using in-depth in vitro B-cell differentiation assays and signaling pathway analysis, we show that CD38 targeting with daratumumab demonstrated a significant decrease in proliferation, differentiation, and IgG production upon T cell–dependent B-cell stimulation. We found no effect on T-cell activation or proliferation. Furthermore, we demonstrate that daratumumab attenuated the activation of NF-?B in B cells and the transcription of NF-?B–targeted genes. When culturing sorted B-cell subsets with daratumumab, the switched memory B-cell subset was primarily affected. Overall, these in vitro data elucidate novel non-depleting mechanisms by which daratumumab can disturb humoral immune responses. Affecting memory B cells, daratumumab may be used as a therapeutic approach in B cell–mediated diseases other than the currently targeted malignancies

Differential Gene Expression Changes in Children with Severe Dengue Virus Infections

Dengue virus infection is an impressively emerging disease that can be fatal in severe cases. It is not precisely clear why some patients progress to severe disease whereas most patients only suffer from a mild infection. In severe disease, a “cytokine storm” is induced, which indicates the release of a great number of inflammatory mediators (“cytokines”). Evidence suggested that a balance could be involved between protective and pathologic cytokine release patterns. We studied this concept in a cohort of Indonesian children with severe dengue disease using a gene expression profiling method