IL-7 withdrawal induces a stress pathway activating p38 and Jun N-terminal kinases

XBP1 promotes NRASG12D pre-B acute lymphoblastic leukaemia through IL-7 receptor signalling and provides a therapeutic vulnerability for oncogenic RAS

Activating point mutations of the RAS gene act as driver mutations for a subset of precursor-B cell acute lymphoblastic leukaemias (pre-B ALL) and represent an ambitious target for therapeutic approaches. The X box-binding protein 1 (XBP1), a key regulator of the unfolded protein response (UPR), is critical for pre-B ALL cell survival, and high expression of XBP1 confers poor prognosis in ALL patients. However, the mechanism of XBP1 activation has not yet been elucidated in RAS mutated pre-B ALL. Here, we demonstrate that XBP1 acts as a downstream linchpin of the IL-7 receptor signalling pathway and that pharmacological inhibition or genetic ablation of XBP1 selectively abrogates IL-7 receptor signalling via inhibition of its downstream effectors, JAK1 and STAT5. We show that XBP1 supports malignant cell growth of pre-B NRASG12D ALL cells and that genetic loss of XBP1 consequently leads to cell cycle arrest and apoptosis. Our findings reveal that active XBP1 prevents the cytotoxic effects of a dual PI3K/mTOR pathway inhibitor (BEZ235) in pre-B NRASG12D ALL cells. This implies targeting XBP1 in combination with BEZ235 as a promising new targeted strategy against the oncogenic RAS in NRASG12D -mutated pre-B ALL.

The Therapeutic Values of IL-7/IL-7R and the Recombinant Derivatives in Glioma: A Narrative Review

Interleukin-7 (IL-7) is essential for maintaining the immune system's defense functions by regulating the development and homeostasis of lymphocytes. Findings have shown the high efficacy of IL-7/IL-7 receptor (IL-7R)-based immunotherapy on various malignancies, with confirmation in both animal models and humans. In recent years, the progression-free survival and overall survival of patients suffering from gliomas significantly increased by introducing C7R-expressing chimeric antigen receptor (CAR)-T cells and long-acting IL-7 agonists such as NT-I7 (rhIL-7-hyFc, Efineptakin alfa). However, the effect of IL-7-based immunotherapies on the resistance of tumor cells to chemotherapy (when used simultaneously with chemotherapy agents) is still ambiguous and requires further studies. This article first reviews the pathophysiological roles of IL-7/IL-7R in tumors, focusing on gliomas. Subsequently, it discusses the therapeutic values of IL-7/IL-7R and the recombinant derivatives in gliomas.

The Role of IL-7 and IL-7R in Cancer Pathophysiology and Immunotherapy

Interleukin-7 (IL-7) is a multipotent cytokine that maintains the homeostasis of the immune system. IL-7 plays a vital role in T-cell development, proliferation, and differentiation, as well as in B cell maturation through the activation of the IL-7 receptor (IL-7R). IL-7 is closely associated with tumor development and has been used in cancer clinical research and therapy. In this review, we first summarize the roles of IL-7 and IL-7Rα and their downstream signaling pathways in immunity and cancer. Furthermore, we summarize and discuss the recent advances in the use of IL-7 and IL-7Rα as cancer immunotherapy tools and highlight their potential for therapeutic applications. This review will help in the development of cancer immunotherapy regimens based on IL-7 and IL-7Rα, and will also advance their exploitation as more effective and safe immunotherapy tools.

Potential Molecular Mechanism of Guishao Pingchan Recipe in the Treatment of Parkinson’s Disease Based on Network Pharmacology and Molecular Docking

Objective: To investigate the potential mechanism of Guishao Pingchan Recipe (GPR) against Parkinson's disease (PD) based on network pharmacology and molecular docking. Methods: The main components of GPR were collected based on TCMSP database, Batman-TCM database, Chinese Pharmacopoeia, and Literatures. The potential therapeutic targets of PD were predicted by Drug Bank Database and Gene Cards database. Cytoscape 3.8.2 software was used to construct herb–component–target network. Then, String database was used to construct a PPI network, and DAVID database was used for gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway annotation of targets function. Core components of GPR and hub targets were imported into AutoDock Vina for molecular docking verification and results were visualized by Pymol. Results: 13 candidate components were selected and 288 corresponding targets of GPR for treating PD were obtained. The GO enrichment analysis mainly involved 135 cell components, 187 molecular functions, and 1753 biological processes. Moreover, KEGG pathway enrichment analysis mainly involved 200 signaling pathways. Molecular docking simulation indicated a good binding ability of components and targets. Conclusion: Based on network pharmacology and molecular docking, we found that sitosterol, 4-Cholesten-3-one and stigmasterol in GPR could combine with MAPK3, APP, VEGFA, and CXCR4 and involved in the cAMP, PI3K/Akt, Rap1 signaling pathways. It is suggested that GPR may have therapeutic effects on PD through multi-component, multi-target, and multi-pathway and predict the relevant mechanism of the anti-PD effect of GPR.

The Broad Immunomodulatory Effects of IL-7 and Its Application In Vaccines

Interleukin-7 (IL-7) is produced by stromal cells, keratinocytes, and epithelial cells in host tissues or tumors and exerts a wide range of immune effects mediated by the IL-7 receptor (IL-7R). IL-7 is primarily involved in regulating the development of B cells, T cells, natural killer cells, and dendritic cells via the JAK-STAT, PI3K-Akt, and MAPK pathways. This cytokine participates in the early generation of lymphocyte subsets and maintain the survival of all lymphocyte subsets; in particular, IL-7 is essential for orchestrating the rearrangement of immunoglobulin genes and T-cell receptor genes in precursor B and T cells, respectively. In addition, IL-7 can aid the activation of immune cells in anti-virus and anti-tumor immunity and plays important roles in the restoration of immune function. These biological functions of IL-7 make it an important molecular adjuvant to improve vaccine efficacy as it can promote and extend systemic immune responses against pathogens by prolonging lymphocyte survival, enhancing effector cell activity, and increasing antigen-specific memory cell production. This review focuses on the biological function and mechanism of IL-7 and summarizes its contribution towards improved vaccine efficacy. We hope to provide a thorough overview of this cytokine and provide strategies for the development of the future vaccines.

Interleukin-7 is required for CD4(+) T cell activation and autoimmune neuroinflammation

IL-7 is known to be vital for T cell homeostasis but has previously been presumed to be dispensable for TCR-induced activation. Here, we show that IL-7 is critical for the initial activation of CD4(+) T cells in that it provides some of the necessary early signaling components, such as activated STAT5 and Akt. Accordingly, short-term in vivo IL-7Rα blockade inhibited the activation and expansion of autoantigen-specific CD4(+) T cells and, when used to treat experimental autoimmune encephalomyelitis (EAE), prevented and ameliorated disease. Our studies demonstrate that IL-7 signaling is a prerequisite for optimal CD4(+) T cell activation and that IL-7R antagonism may be effective in treating CD4(+) T cell-mediated neuroinflammation and other autoimmune inflammatory conditions.

The major isoforms of Bim contribute to distinct biological activities that govern the processes of autophagy and apoptosis in interleukin-7 dependent lymphocytes

Bim is a BH3-only member of the Bcl-2 family that enables the death of T-cells. Partial rescue of cytokine-deprived T-cells occurs when Bim and the receptor for the T-cell growth factor, interleukin-7, are deleted, implicating Bim as a possible target of interleukin-7-mediated signaling. Alternative splicing yields three major isoforms: BimEL, BimL and BimS. To study the effect of Bim deficiency and define the function of the major isoforms, Bim-containing and Bim-deficient T-cells, dependent on interleukin-7 for growth, were used. Loss of total Bim in interleukin-7-deprived T-cells resulted in delayed apoptosis. However, loss of Bim also impeded the later degradative phase of autophagy. p62, an autophagy-adaptor protein which is normally degraded, accumulated in Bim deficient cells. To explain this, BimL was found to support acidification of lysosomes that later may associate with autophagic vesicles. Key findings showed that inhibition of lysosomal acidification accelerated death upon interleukin-7 withdrawal only in Bim-containing T-cells. intereukin-7 dependent T-cells lacking Bim were less sensitive to inhibition of lysosomal acidification. BimL co-immunoprecipitated with dynein and Lamp1-containing vesicles, indicating BimL could be an adaptor for dynein to facilitate loading of lysosomes. In Bim deficient T-cells, lysosome-tracking probes revealed vesicles of less acidic pH. Over-expression of BimL restored acidic vesicles in Bim deficient T-cells, while other isoforms, BimEL and BimS, promoted intrinsic cell death. These results reveal a novel role for BimL in lysosomal positioning that may be required for the formation of degradative autolysosomes.

Increased CD4+ T cell levels during IL-7 administration of antiretroviral therapy-treated simian immunodeficiency virus-positive macaques are not dependent on strong proliferative responses

CD4(+) T cell depletion is a fundamental component of HIV infection and AIDS pathogenesis and is not always reversed following antiretroviral therapy (ART). In this study, the SIV-infected rhesus macaque model was used to assess recombinant simian IL-7 in its glycosylated form (rsIL-7gly) to enhance regeneration of CD4(+) T cells, particularly the crucial central memory compartment, after ART. We assessed the impact of rsIL-7gly administration as single injections and as a cluster of three doses. Irrespective of the dosing strategy used, the rsIL-7gly administration transiently increased proliferation of both central memory and naive cells, in both CD4(+) and CD8(+) subsets, without increasing SIV levels in the blood. Administration of rsIL-7gly at intervals of 4-6 wk maximized the proliferative response to therapy but resulted in only transient increases in peripheral blood T cell counts. Although more frequent rsIL-7gly "clustered" dosing (three times weekly with 2 wk of rest and then repeat) induced only an initial proliferative burst by CD4(+) T cells, this dosing strategy resulted in sustained increases in peripheral blood CD4(+) T cell counts. The clustered rsIL-7gly treatment regimen was shown to increase the half-life of a BrdU label among memory T cells in the blood when compared with that of macaques treated with ART alone, which is consistent with enhanced cell survival. These results indicate that dosing intervals have a major impact on the response to rsIL-7gly in SIV-positive ART-treated rhesus macaques and that optimum dosing strategies may be ones that induce CD4(+) T cell proliferation initially and provide increased CD4(+) T cell survival.

Interleukin-7 regulates Bim proapoptotic activity in peripheral T-cell survival

Interleukin-7 (IL-7) is critical for T-cell development and peripheral T-cell homeostasis. The survival of pro-T cells and mature T cells requires IL-7. The survival function of IL-7 is accomplished partly through induction of the antiapoptotic protein Bcl-2 and inhibition of proapoptotic proteins Bax and Bad. We show here that the proapoptotic protein Bim, a BH3-only protein belonging to the Bcl-2 family, also plays a role in peripheral T-cell survival. Deletion of Bim partially protected an IL-7-dependent T-cell line and peripheral T cells, especially cells with an effector memory phenotype, from IL-7 deprivation. However, T-cell development in the thymus was not restored in IL-7(-/-) Rag2(-/-) mice reconstituted with Bim(-/-) bone marrow. IL-7 withdrawal altered neither the intracellular location of Bim, which was constitutively mitochondrial, nor its association with Bcl-2; however, a reduction in its association with the prosurvival protein Mcl-1 was observed. IL-7 withdrawal did not increase Bim mRNA or protein expression but did induce changes in the isoelectric point of Bim(EL) and its reactivity with an antiphosphoserine antibody. Our findings suggest that the maintenance of peripheral T cells by IL-7 occurs partly through inhibition of Bim activity at the posttranslational level.

Critical role for Rsk2 in T-lymphocyte activation

During T-cell activation, a number of cytokine-activated signaling cascades, including the Jak-STAT, phosphoinositol 3-kinase (PI 3-kinase), and mitogen-activated protein kinase (MAPK) pathways, play important roles in modulating the expression of target genes and mediating a cellular response. We now report that interleukin 2 (IL-2) and IL-15, but not IL-7, rapidly activate the p90 ribosomal S6 kinases, Rsk1 and Rsk2, in human T lymphocytes. Surprisingly, mouse spleen T cells transduced with either the wild-type or a dominant-negative (DN) Rsk2-expressing retrovirus could not be recovered, in contrast to the normal survival of T cells transduced with retroviruses expressing wild-type or DN mutants of Rsk1 or Rsk3. Examination of Rsk2 knockout (KO) mice revealed normal T-cell development, but these T cells had delayed cell-cycle progression and lower production of IL-2 in response to anti-CD3 and anti-CD28 stimulation in vitro. Moreover, Rsk2 KO mice had defective homeostatic T-cell expansion following sublethal irradiation in vivo, which is known to involve T-cell receptor (TCR), IL-2, and/or IL-15 signals, each of which we demonstrate can rapidly and potently activate Rsk2 in mouse T cells. These results indicate an essential nonredundant role of Rsk2 in T-cell activation.

IL-2 withdrawal induces HTLV-1 expression through p38 activation in ATL cell lines

Expression of human T-cell leukemia virus type-1 (HTLV-1) in adult T-cell leukemia (ATL) cells is known to be marginal in vivo and inducible in short-term culture. In this study, we demonstrated that withdrawal of interleukin (IL)-2 from IL-2-dependent ATL cell lines resulted in induction of HTLV-1 mRNA and protein expression, and that viral induction was associated with phosphorylation of the stress kinase p38 and its downstream CREB. Pharmacological inhibitors of the p38 pathway suppressed viral expression induced by IL-2 depletion. These results indicate that the stress-induced p38 pathway might up-regulate HTLV-1 gene expression through at least CREB activation.

Interlinking interleukin-7

The signaling processes that maintain the homeostatic proliferation of peripheral T-cells and result in their self-renewal largely remain to be elucidated. Much focus has been placed on the anti-apoptotic function of the cytokine, interleukin-7 (IL-7), during T-cell development. But a more critical role has been ascribed to IL-7 as a mediator of peripheral T-cell maintenance. The biological effects responsive to IL-7 signaling are transduced through only a few well-known pathways. In this review we will focus on the signals transduced by IL-7 and similar cytokines, examining how proliferative signals originate from cytokine receptors, are amplified and eventually alter gene expression. In this regard we will highlight the crosstalk between pathways that promote survival, drive cell cycle progression and most importantly provide the needed energy to sustain these critical cellular activities. Though this review showcases much of what has been learned about IL-7 proliferative signaling, it also reveals the significant gaps in our knowledge about cytokine signaling in the very relevant context of peripheral T-cell homeostasis.

Effect of ammonia on ciliary neurotrophic factor mRNA and protein expression and its upstream signalling pathway in cultured rat astroglial cells: possible implication of c-fos, Sp1 and p38MAPK

Ciliary neurotrophic factor (CNTF) may be implicated in the pathogenetic mechanisms of hepatic encephalopathy. We tested this hypothesis by treating confluent primary cultures of rat astroglial cells with ammonium chloride for various periods and analysing the effect of ammonia on the signalling pathway that regulates CNTF mRNA and protein expression. Ammonia treatment induced a dose- and time-dependent reduction in CNTF mRNA and protein expression. Surface-enhanced laser desorption/ionization-time-of-flight mass spectrometry analysis of CNTF in the culture medium demonstrated that ammonia also induced a significant decrease in CNTF release. In addition, ammonia affected Sp1 and c-fos, transcription factors that regulate CNTF mRNA and protein expression, which showed partial dephosphorylation and significantly lower mRNA and protein levels. Total content of p38MAPK (for which Sp1 and c-fos are substrates) was unaffected by ammonia, although the diphosphorylated (active) form was significantly reduced after ammonia exposure.

Molecular and functional evidence for activity of murine IL-7 on human lymphocytes

Although interleukin-7 (IL-7) is essential for human and murine lymphopoiesis and homeostasis, clear disparities between these species regarding the role of IL-7 during B-cell development suggest that other, subtler differences may exist. One basic unsolved issue of IL-7 biology concerns cross-species activity, because in contrast to the human ortholog, the ability of murine (m)IL-7 to stimulate human cells remains unresolved. Establishing whether two-way cross-species reactivity occurs is fundamental for evaluating the role of IL-7 in chimeric human-mouse models, which are the most versatile tools for studying human lymphoid development and disease in vivo. Here, we show that mIL-7 triggers the same signaling pathways as human (h)IL-7 in human T cells, promoting similar changes in viability, proliferation, size, and immunophenotype, even at low concentrations. This ability is not confined to T cells, because mIL-7 mediates cell growth and protects human B-cell precursors from dexamethasone-induced apoptosis. Importantly, endogenous mIL-7 produced in the mouse thymic microenvironment stimulates human T cells, because their expansion in chimeric fetal thymic organ cultures is inhibited by a mIL-7-specific neutralizing antibody. Our results demonstrate that mIL-7 affects human lymphocytes and indicate that mouse models of human lymphoid development and disease must integrate the biological effects of endogenous IL-7 on human cells.

Role of interleukin-7 in bone and T-cell homeostasis

Initially defined as a B-cell growth factor, the pleiotropic nature of interleukin-7 (IL-7) has increasingly become appreciated. Besides its well-known roles in B- and T-cell lymphopoiesis, IL-7 is now known to regulate the homeostasis of both mature T cells and bone cells. In bone, the precise nature of how IL-7 affects osteoclasts and osteoblasts is controversial, since it has a variety of actions in different target cells. These activities are gender-specific and are dependent on whether IL-7 is delivered systemically or locally. In mature T cells, IL-7 is essential for the survival of nearly all subsets. Naïve T cells are also dependent on IL-7 for survival and homeostatic proliferation in response to lymphopenia. In addition, IL-7 plays a role in the survival of memory CD8+ cells, and at high concentrations, it can compensate for the absence of IL-15. The role of IL-7 on memory CD4+ cells remains controversial and has yet to be firmly established.

Cell biology of IL-7, a key lymphotrophin

IL-7 is essential for the development and survival of T lymphocytes. This review is primarily from the perspective of the cell biology of the responding T cell. Beginning with IL-7 receptor structure and regulation, the major signaling pathways appear to be via PI3K and Stat5, although the requirement for either has yet to be verified by published knockout experiments. The proliferation pathway induced by IL-7 differs from conventional growth factors and is primarily through posttranslational regulation of p27, a Cdk inhibitor, and Cdc25a, a Cdk-activating phosphatase. The survival function of IL-7 is largely through maintaining a favorable balance of bcl-2 family members including Bcl-2 itself and Mcl-1 on the positive side, and Bax, Bad and Bim on the negative side. There are also some remarkable metabolic effects of IL-7 withdrawal. Studies of IL-7 receptor signaling have yet to turn up unique pathways, despite the unique requirement for IL-7 in T cell biology. There remain significant questions regarding IL-7 production and the major producing cells have yet to be fully characterized.

Cytokine-driven cell cycling is mediated through Cdc25A

Lymphocytes are the central mediators of the immune response, requiring cytokines for survival and proliferation. Survival signaling targets the Bcl-2 family of apoptotic mediators, however, the pathway for the cytokine-driven proliferation of lymphocytes is poorly understood. Here we show that cytokine-induced cell cycle progression is not solely dependent on the synthesis of cyclin-dependent kinases (Cdks) or cyclins. Rather, we observe that in lymphocyte cell lines dependent on interleukin-3 or interleukin-7, or primary lymphocytes dependent on interleukin 7, the phosphatase Cdc25A is the critical mediator of proliferation. Withdrawal of IL-7 or IL-3 from dependent lymphocytes activates the stress kinase, p38 MAPK, which phosphorylates Cdc25A, inducing its degradation. As a result, Cdk/cyclin complexes remain phosphorylated and inactive and cells arrest before the induction of apoptosis. Inhibiting p38 MAPK or expressing a mutant Cdc25A, in which the two p38 MAPK target sites, S75 and S123, are altered, renders cells resistant to cytokine withdrawal, restoring the activity of Cdk/cyclin complexes and driving the cell cycle independent of a growth stimulus.

Characterization of Cd-induced molecular events prior to cellular damage in primary rat hepatocytes in culture: activation of the stress activated signal protein JNK and transcription factor AP-1

The effect of Cadmium (Cd) on the expression of c-Jun N-terminal kinase (JNK), c-jun, and activator protein-1 (AP-1) has been investigated. We previously reported that Cd causes cell damage as indicated by increases in the cytotoxic parameters, lactate dehydrogenase and lipid peroxidation, and this damage was mediated by decreases in cellular concentration of glutathione. In the present study, we investigate the molecular events involved prior to the Cd-induced cellular toxicity and damage in primary rat hepatocytes. We propose that Cd, through the generation of reactive oxygen species (ROS) and prior to significant cellular damage, activates the stress activated signal protein JNK, regulates c-jun expression, and promotes the binding of a redox sensitive transcription factor AP-1. We show JNK activity and c-jun mRNA level significantly increased at 1 h and AP-1 DNA binding activity significantly enhanced at 3 h in the presence of 4 microM cadmium chloride. Blocking the Cd induction of JNK activity, c-jun mRNA level, and AP-1 binding activity using the antioxidants N-acetyl cysteine (10 mM) or carnosol (0.5 microg/mL) suggests a role for ROS. Blocking JNK activity and c-jun mRNA by SP600125 (20 microM), a JNK inhibitor, supports the role of JNK in transmission of signals induced by Cd.

Lymphocide: cytokines and the control of lymphoid homeostasis

In a human, about 10(11) excess peripheral lymphocytes die every day. This death process maintains a constant lymphocyte population size in the face of a continuous influx of new lymphocytes and the homeostatic proliferation of old ones. Death is triggered when a lymphocyte fails to acquire signals from survival factors, the availability of which, therefore, determines the size of the pool of lymphocytes. A lymphocyte acquires survival signals through receptors for cytokines, antigens, hormones and probably other extracellular factors. Here, we discuss current concepts of the intracellular signalling pathways for survival versus death that establish cytokine-regulated lymphocyte homeostasis.