IκB kinase β is required for activation of NF-κB and AP-1 in CD3/CD28-stimulated primary CD4(+) T cells

Ampk Activation Attenuates Her3 Upregulation And Neuregulin-Mediated Rescue of Cell Proliferation in Her2-Overexpressing Breast Cancer Cell Lines Exposed to Lapatinib

Lapatinib is a highly selective reversible inhibitor of the tyrosine kinase domains of HER2 and EGFR, approved for the treatment of advanced stage HER2-overexpressing breast cancers. Although targeted therapy with lapatinib provides initial clinical advantage, cancer cells' adaptive responses can overcome the inhibitory effects of lapatinib. HER3 upregulation and autocrine induction of HER3 ligand neuregulin-1 (NRG), have been implicated in the restoration of AKT and ERK1/2 activity and rescue of cell proliferation. In this study we evaluated the effects of lapatinib alone and in combination with AMPK activator GSK-621 in HER2-overexpressing breast cancer cell lines SKBR3 and BT474. Our results show that in cells exposed to lapatinib and GSK-621 in combination, lapatinib-mediated HER3 upregulation was reduced and reactivation of AKT and ERK1/2 kinases was prevented. The two drugs in combination decreased cell viability in a synergistic manner and greatly reduced the ability of NRG to rescue cell proliferation. Finally, we provide evidence that in cells exposed to lapatinib and GSK-621 in combination the establishment of a transcriptionally permissive chromatin structure at the HER3 promoter is hampered. The results of this study highlight a potential role for AMPK activation in counteracting lapatinib-induced adaptive responses of HER2-overexpressing breast cancer cells.

Diacylglycerol kinase ζ limits IL-2-dependent control of PD-1 expression in tumor-infiltrating T lymphocytes

Background

The inhibitory functions triggered by the programmed cell death-1 (PD-1) receptor following binding to its ligand (PD-L1) protect healthy organs from cytotoxic T cells, and neutralize antitumor T cell attack. Antibody-based therapies to block PD-1/PD-L1 interaction have yielded notable results, but most patients eventually develop resistance. This failure is attributed to CD8⁺ T cells achieving hyporesponsive states from which recovery is hardly feasible. Dysfunctional T cell phenotypes are favored by a sustained imbalance in the diacylglycerol (DAG)- and Ca²⁺-regulated transcriptional programs. In mice, DAG kinase ζ (DGKζ) facilitates DAG consumption, limiting T cell activation and cytotoxic T cell responses. DGKζ deficiency facilitates tumor rejection in mice without apparent adverse autoimmune effects. Despite its therapeutic potential, little is known about DGKζ function in human T cells, and no known inhibitors target this isoform.

Methods

We used a human triple parameter reporter cell line to examine the consequences of DGKζ depletion on the transcriptional restriction imposed by PD-1 ligation. We studied the effect of DGKζ deficiency on PD-1 expression dynamics, as well as the impact of DGKζ absence on the in vivo growth of MC38 adenocarcinoma cells.

Results

We demonstrate that DGKζ depletion enhances DAG-regulated transcriptional programs, promoting interleukin-2 production and partially counteracting PD-1 inhibitory functions. DGKζ loss results in limited PD-1 expression and enhanced expansion of cytotoxic CD8⁺ T cell populations. This is observed even in immunosuppressive milieus, and correlates with the reduced ability of MC38 adenocarcinoma cells to form tumors in DGKζ-deficient mice.

Conclusions

Our results, which define a role for DGKζ in the control of PD-1 expression, confirm DGKζ potential as a therapeutic target as well as a biomarker of CD8⁺ T cell dysfunctional states.

Combined immunodeficiency caused by a novel homozygous NFKB1 mutation

BACKGROUND

Genetic faults in several components of the nuclear factor-κB pathway cause immunodeficiency. Most defects lead to combined immunodeficiency with a range of severity. Heterozygous mutations in NFKB1 were associated with common variable immunodeficiency, however, homozygous mutations have not been described.

OBJECTIVE

We studied the molecular basis of combined immunodeficiency in a patient who presented with failure to thrive, persistent EBV viremia and hepatitis, pneumocystis jirovecii pneumonitis, and generalized lymphadenopathy.

METHODS

Whole genome and exome sequencing followed by Sanger confirmation were performed to identify the genetic defect. Molecular and cellular techniques were used to assess the variant impact on the nuclear factor-κB pathway and lymphocyte function.

RESULTS

Genetic analysis revealed a novel homozygous mutation in NFKB1, c.2878G>A, p.Gly960Arg (G960R). This affected p105 phosphorylation and p50 formation on antigen and cytokine stimulation, as well as attenuating nuclear signal transmission. As a result, both T- and B-cell maturation and function were perturbed. The number of memory CD4⁺ T cells were reduced, while CD8⁺ T cells consisted predominately of expanded differentiated populations. The function of T cells were diminished as shown by reduced responses to mitogens as well as diminished cytokine secretion. B-cell maturation was also affected, with decreased IgD⁺CD27⁺ memory B cells while transitional B cells were increased, likely contributing to the reduced ability to produce specific antibodies.

CONCLUSION

Homozygous G960R mutation in NFKB1 leads to a severe clinical presentation of combined immunodeficiency. This was associated with blockade of nuclear factor-κB pathway signaling, resulting in aberrations in T- and B-cell maturation and function.

Anti-B-cell Maturation Antigen Chimeric Antigen Receptor T cell Function against Multiple Myeloma Is Enhanced in the Presence of Lenalidomide

Anti-B-cell maturation antigen (BCMA) chimeric antigen receptor (CAR) T cells have shown promising clinical responses in patients with relapsed/refractory multiple myeloma. Lenalidomide, an immunomodulatory drug, potentiates T cell functionality, drives antimyeloma activity, and alters the suppressive microenvironment; these properties may effectively combine with anti-BCMA CAR T cells to enhance function. Using an anti-BCMA CAR T, we demonstrated that lenalidomide enhances CAR T cell function in a concentration-dependent manner. Lenalidomide increased CAR T effector cytokine production, particularly under low CAR stimulation or in the presence of inhibitory ligand programmed cell death 1 ligand 1. Notably, lenalidomide also enhanced CAR T cytokine production, cytolytic activity, and activation profile relative to untreated CAR T cells in chronic stimulation assays. This unique potentiation of both short-term CAR T activity and long-term functionality during chronic stimulation prompted investigation of the molecular profile of lenalidomide-treated CAR T cells. Signatures from RNA sequencing and assay for transposase-accessible chromatin using sequencing indicated that pathways associated with T-helper 1 response, cytokine production, T cell activation, cell-cycle control, and cytoskeletal remodeling were altered with lenalidomide. Finally, study of lenalidomide and anti-BCMA CAR T cells in a murine, disseminated, multiple myeloma model indicated that lenalidomide increased CAR T cell counts in blood and significantly prolonged animal survival. In summary, preclinical studies demonstrated that lenalidomide potentiated CAR T activity in vivo in low-antigen or suppressive environments and delayed onset of functional exhaustion. These results support further investigation of lenalidomide and anti-BCMA CAR T cells in the clinic.

NF-κB pathway and the Goldilocks principle: Lessons from human disorders of immunity and inflammation

Nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) signaling pathways play a key role in various cell processes related to host immunity. The last few years have seen an explosion of disorders associated with NF-κB components from core members of the canonical and noncanonical cascades to adaptor protein and ubiquitination-related enzymes. Disease phenotypes have extended beyond susceptibility to infections and include autoimmunity, lymphoproliferation, atopy, and inflammation. Concurrently, studies are unveiling a tightly regulated system marked by extensive cross-talk between the canonical and noncanonical pathways, as well as among the NF-κB and other signaling pathways. As the rate of discovery in the realm of NF-κB defects accelerates, this review presents a timely summary of major known defects causing human disease, as well as diagnostic, therapeutic, and research challenges and opportunities.

Maraviroc Is Associated with Latent HIV-1 Reactivation through NF-κB Activation in Resting CD4+ T Cells from HIV-Infected Individuals on Suppressive Antiretroviral Therapy

Maraviroc is a CCR5 antagonist used in the treatment of HIV-1 infection. We and others have suggested that maraviroc could reactivate latent HIV-1. To test the latency-reversing potential of maraviroc and the mechanisms involved, we performed a phase II, single-center, open-label study in which maraviroc was administered for 10 days to 20 HIV-1-infected individuals on suppressive antiretroviral therapy (EudraCT registration no. 2012-003215-66). All patients completed full maraviroc dosing and follow-up. The primary endpoint was to study whether maraviroc may reactivate HIV-1 latency, eliciting signaling pathways involved in the viral reactivation. An increase in HIV-1 transcription in resting CD4⁺ T cells, estimated by levels of HIV-1 unspliced RNA, was observed. Moreover, activation of the NF-κB transcription factor was observed in these cells. To elucidate the mechanism of NF-κB activation by maraviroc, we have evaluated in HeLa P4 C5 cells, which stably express CCR5, whether maraviroc could be acting as a partial CCR5 agonist, with no other mechanisms or pathways involved. Our results show that maraviroc can induce NF-κB activity and that NF-κB targets gene expression by CCR5 binding, since the use of TAK779, a CCR5 inhibitor, blocked NF-κB activation and functionality. Taking the results together, we show that maraviroc may have a role in the activation of latent virus transcription through the activation of NF-κB as a result of binding CCR5. Our results strongly support a novel use of maraviroc as a potential latency reversal agent in HIV-1-infected patients.IMPORTANCE HIV-1 persistence in a small pool of long-lived latently infected resting CD4⁺ T cells is a major barrier to viral eradication in HIV-1-infected patients on antiretroviral therapy. A potential strategy to cure HIV-1-infection is the use of latency-reversing agents to eliminate the reservoirs established in resting CD4⁺ T cells. As no drug has been shown to be completely effective so far, the search for new drugs and combinations remains a priority for HIV cure. We examined the ability of maraviroc, a CCR5 antagonist used as an antiretroviral drug, to activate latent HIV-1 in infected individuals on antiretroviral therapy. The study showed that maraviroc can activate NF-κB and, subsequently, induce latent HIV-1-transcription in resting CD4⁺ T cells from HIV-1-infected individuals on suppressive antiretroviral therapy. Additional interventions will be needed to eliminate latent HIV-1 infection. Our results suggest that maraviroc may be a new latency-reversing agent to interfere with HIV-1 persistence during antiretroviral therapy.

Geraniin Inhibits LPS-Induced THP-1 Macrophages Switching to M1 Phenotype via SOCS1/NF-κB Pathway

M1 macrophage polarization is proved to promote inflammation in atherosclerosis process. In this study, we evaluated the inhibitory effect of geraniin, a bioactive polyphenolic compound, on the LPS-induced switch of THP-1 macrophages to M1 phenotype, and we propose a molecular basis for its action. Flow cytometry analysis indicated that geraniin significantly inhibited LPS-induced M1 macrophage polarization. Geraniin downregulated the protein and the mRNA level of typical cytokines of M1 macrophage, including tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6), indicating that geraniin can suppress typical mediators of M1 macrophage at the transcriptional level. Moreover, geraniin inhibited LPS-induced reactive oxygen species (ROS) and nitric oxide (NO) production, as well as inducible nitric oxide synthase (iNOS) activity, in THP-1 macrophages. Furthermore, western blot analysis indicated that geraniin decreased both LPS-induced phosphorylation of NF-κB-p65 and NF-κB-p65 expression without affecting the level of IκB-α. This suggested that geraniin inhibited NF-κB, a transcription factor pivotal in the LPS-induced expression of pro-inflammatory genes and an important player in M1 macrophage polarization. Moreover, an electrophoretic mobility shift assay (EMSA) demonstrated that geraniin blocked the LPS-induced translocation of NF-κB to the nucleus. Moreover, we found that geraniin up-regulated the expression of SOCS1, an upstream regulator of NF-κB activation that can directly bind to NF-κB-p65 and downregulate it, thus inhibiting NF-κB activation. In conclusion, geraniin inhibits LPS-induced THP-1 macrophages switching to M1 phenotype through SOCS1/NF-κB pathway.

Effects of different TLR ligands on the expression of proinflammatory cytokines and avian β-defensins in the uterine and vaginal tissues of laying hens

The immune response in the lower part of the hen oviduct is of crucial importance to protect the oviductal tissues from infection by microorganisms colonizing the cloaca. The aim of this study was to examine whether different TLRs can recognize their ligands to induce expression of proinflammatory cytokines and avian β-defensins (AvBDs) in the uterus and vagina of laying hens. The mucosal tissues of the uterus and vagina were collected, cultured in TCM-199 medium and stimulated with or without different ligands of TLRs, namely Pam3CSK4 (TLR2), poly I:C (TLR3), flagellin (TLR5), R848 (TLR7), and CpG-ODN (TLR21) and incubated for 3h. The expression of IL1B in the uterus and vagina was upregulated by all TLR ligands tested. The expression of IL6 in the uterus and vagina was upregulated by poly I:C and CpG-ODN, and it was also upregulated by Pam3CSK4 in the uterus and by R848 in the vagina. The expression of AvBD10 was upregulated by poly I:C in the uterus and by flagellin in the vagina. On the other hand, the AvBD10 expression was downregulated by CpG-ODN in the uterus and by R848 in the vagina, whereas its expression was not affected by Pam3CSK4 in both tissues. The expression of AvBD12 in the uterus and vagina was not affected by any TLR ligands except for CpG-ODN, which downregulated its expression in the vagina. These results suggest that TLR2, 3, 5, 7, and 21 in the uterine and vaginal tissues are functionally active in inducing proinflammatory cytokines in response to their specific ligands, although the effect on the expression of AvBDs is limited. Proinflammatory cytokines induced by interaction of TLRs with their ligands may play roles in the defense against infectious microorganisms.

Exposure of neuroblastoma cell lines to imatinib results in the upregulation of the CDK inhibitor p27(KIP1) as a consequence of c-Abl inhibition

Imatinib mesylate is a tyrosine kinase inhibitor with selectivity for abelson tyrosine-protein kinase 1 (c-Abl), breakpoint cluster region (Bcr)-Abl fusion protein (Bcr-Abl), mast/stem cell growth factor receptor Kit (c-Kit), and platelet-derived growth factor receptor (PDGFR). Previous studies demonstrated that imatinib in the low micromolar range exerted antiproliferative effects on neuroblastoma cell lines. However, although neuroblastoma cells express c-Kit and PDGFR, the imatinib concentrations required to achieve significant growth inhibitory effects (≥ 10 μM) are substantially higher than those required for inhibition of ligand-induced phosphorylation of wild type c-Kit and PDGFR (≤ 1 μM), suggesting that additional mechanisms are responsible for the antitumor activity of imatinib on these cells. In this study, we show that treatment of neuroblastoma cell lines with 1-15 μM imatinib resulted in a dose dependent inhibition of 5-bromo-2'-deoxyuridine (BrdU) incorporation into newly synthesized DNA. The antiproliferative effect of imatinib was dependent on the upregulation of the cyclin-dependent kinase (CDK) inhibitor p27(KIP1) in the nuclear compartment as a result of increased p27(KIP1) protein stability. We demonstrate that the mechanism of p27(KIP1) stabilization relied on inhibition of p27(KIP1) phosphorylation on tyrosine residues by c-Abl. We provide evidence that in neuroblastoma cell lines a significant fraction of cellular c-Abl is phosphorylated on Tyr-245, consistent with an open and active conformation. Notably, exposure to imatinib did not affect Tyr-245 phosphorylation. Given the low affinity of active c-Abl for imatinib, these data provide a molecular explanation for the relatively high imatinib concentrations required to inhibit neuroblastoma cell proliferation.

Immunodeficiency associated with a nonsense mutation of IKBKB

We report an infant of consanguineous parents of Turkish decent with a novel immunodeficiency associated with homozygosity for a nonsense mutation of the gene encoding Inhibitor of nuclear factor kappa-B (NF-κB) kinase subunit beta (IKKβ). At five months, she presented with respiratory insufficiency and Pneumocystis jirovecii pneumonia which was successfully treated. At nine months, iatrogenic systemic infection with Mycobacterium bovis was found and eventually led to her death at age 14 months. Laboratory findings were reminiscent of hyper-IgM syndrome, but genetic testing gave no explanation before whole exome sequencing revealed a novel mutation abrogating signaling through the canonical NF-κB pathway.

Gene expression profiling of Epstein-Barr virus-positive diffuse large B-cell lymphoma of the elderly reveals alterations of characteristic oncogenetic pathways

Epstein–Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) of the elderly (EBV[+]DLBCL-E) is classified as a subtype of DLBCL. Until now, its molecular pathogenesis has remained unknown. To identify pathways characteristic of EBV(+)DLBCL-E, gene expression profiling of five EBV(+)DLBCL-E and seven EBV-negative DLBCL (EBV[−]DLBCL) cases was undertaken using human oligonucleotide microarray analysis. Gene set enrichment analysis and gene ontology analysis showed that gene sets of the Janus kinase-signal transducer and activator of transcription (JAK-STAT) and nuclear factor kappa B (NF-κB) pathways were enriched in EBV(+)DLBCL-E cases. To confirm the results of the expression profiles, in vitro analysis was performed. Expression profiling analysis showed that high activation of the JAK-STAT and NF-κB pathways was induced by EBV infection into DLBCL cell lines. Activation of the NF-κB pathway was confirmed in EBV-infected cell lines using an electrophoretic mobility shift assay. Western blot analysis revealed an increased protein expression level of phosphorylated signal transducer and activator of transcription 3 (STAT3) in an EBV-infected cell line. Protein expression of phosphorylated STAT3 was frequently observed in lymphoma cells of EBV(+)DLBCL-E clinical samples using immunohistochemistry (EBV[+]DLBCL-E: 80.0% [n = 20/25] versus EBV[−]DLBCL: 38.9% [n = 14/36]; P = 0.001). The results of the present study suggest that activation of the JAK-STAT and NF-κB pathways was characteristic of EBV(+)DLBCL-E, which may reflect the nature of EBV-positive tumor cells. Targeting these pathways as therapies might improve clinical outcomes of EBV(+)DLBCL-E.

Deficiency of innate and acquired immunity caused by an IKBKB mutation

BACKGROUND

Severe combined immunodeficiency (SCID) comprises a heterogeneous group of heritable deficiencies of humoral and cell-mediated immunity. Many patients with SCID have lymphocyte-activation defects that remain uncharacterized.

METHODS

We performed genetic studies in four patients, from four families of Northern Cree ancestry, who had clinical characteristics of SCID, including early onset of severe viral, bacterial, and fungal infections despite normal B-cell and T-cell counts. Genomewide homozygosity mapping was used to identify a candidate region, which was found on chromosome 8; all genes within this interval were sequenced. Immune-cell populations, signal transduction on activation, and effector functions were studied.

RESULTS

The patients had hypogammaglobulinemia or agammaglobulinemia, and their peripheral-blood B cells and T cells were almost exclusively of naive phenotype. Regulatory T cells and γδ T cells were absent. All patients carried a homozygous duplication--c.1292dupG in exon 13 of IKBKB, which encodes IκB kinase 2 (IKK2, also known as IKKβ)--leading to loss of expression of IKK2, a component of the IKK-nuclear factor κB (NF-κB) pathway. Immune cells from the patients had impaired responses to stimulation through T-cell receptors, B-cell receptors, toll-like receptors, inflammatory cytokine receptors, and mitogens.

CONCLUSIONS

A form of human SCID is characterized by normal lymphocyte development despite a loss of IKK2 function. IKK2 deficiency results in an impaired response to activation stimuli in a variety of immune cells, leading to clinically relevant impairment of adaptive and innate immunity. Although Ikk2 deficiency is lethal in mouse embryos, our observations suggest a more restricted, unique role of IKK2-NF-κB signaling in humans. (Funded by the German Federal Ministry of Education and Research and others.).

TLR5 signaling enhances the proliferation of human allogeneic CD40-activated B cell induced CD4hiCD25+ regulatory T cells

Although diverse functions of different toll-like receptors (TLR) on human natural regulatory T cells have been demonstrated recently, the role of TLR-related signals on human induced regulatory T cells remain elusive. Previously our group developed an ex vivo high-efficient system in generating human alloantigen-specific CD4^hiCD25⁺ regulatory T cells from naïve CD4⁺CD25⁻ T cells using allogeneic CD40-activated B cells as stimulators. In this study, we investigated the role of TLR5-related signals on the generation and function of these novel CD4^hiCD25⁺ regulatory T cells. It was found that induced CD4^hiCD25⁺ regulatory T cells expressed an up-regulated level of TLR5 compared to their precursors. The blockade of TLR5 using anti-TLR5 antibodies during the co-culture decreased CD4^hiCD25⁺ regulatory T cells proliferation by induction of S phase arrest. The S phase arrest was associated with reduced ERK1/2 phosphorylation. However, TLR5 blockade did not decrease the CTLA-4, GITR and FOXP3 expressions, and the suppressive function of CD4^hiCD25⁺ regulatory T cells. In conclusion, we discovered a novel function of TLR5-related signaling in enhancing the proliferation of CD4^hiCD25⁺ regulatory T cells by promoting S phase progress but not involved in the suppressive function of human CD40-activated B cell-induced CD4^hiCD25⁺ regulatory T cells, suggesting a novel role of TLR5-related signals in the generation of induced regulatory T cells.

Transgenic expression of IL-33 activates CD8(+) T cells and NK cells and inhibits tumor growth and metastasis in mice

IL-33 is a multifunctional cytokine in immune regulation that activates Th1 cells, Th2 cells, CD8(+) T cells and NK cells. Our study showed that transgenic expression of IL-33 attenuated tumor metastasis in the B16 melanoma and Lewis lung carcinoma (LLC) metastatic models. The percentages and cytotoxicity of CD8(+) T cells and NK cells and their infiltration into the tumor tissues were significantly increased by the transgenic expression of IL-33 in tumor-bearing mice. Treatment with recombinant IL-33 could also increase the cytotoxicity of CD8(+) T cells and NK cells in vitro. In addition, depletion of CD8(+) T cells and NK cells using anti-CD8 or anti-asialo GM1 antibody abolished the pulmonary metastasis inhibition mediated by IL-33. Furthermore, IL-33 stimulated the activation of NF-κB and increased CD69 expression, which is a marker of the activated form of the two cell subsets, in CD8(+) T cells and NK cells. Our results suggest that IL-33 stimulated NF-κB signaling and promoted the proliferation, activation and infiltration of CD8(+) T cells and NK cells, which resulted in the inhibition of pulmonary metastasis in B16 melanoma and LLC mice models.