The NF-kappa B cascade is important in Bcl-xL expression and for the anti-apoptotic effects of the CD28 receptor in primary human CD4+ lymphocytes

The adaptation model of immunity: is the goal of central tolerance to eliminate defective T cells or self‐reactive T cells?

The self‐non‐self model and the danger model are designed to understand how an immune response is induced. These models are not meant to predict if an immune response may succeed or fail in destroying/controlling its target. However, these immunological models rely on either self‐antigens or self‐dendritic cells for understanding of central tolerance, which have been discussed by Fuchs and Matzinger in response to Al‐Yassin. In an attempt to address some questions that these models are facing when it comes to understanding central tolerance, I propose that the goal of negative selection in the thymus is to eliminate defective T cells but not self‐reactive T cells. Therefore, any escape from negative selection could increase lymphopenia because of the depletion of defective naïve T cells outside the thymus, as seen in the elderly.

Alpha-Tocotrienol Enhances Arborization of Primary Hippocampal Neurons via Upregulation of Bcl-xL

Alpha-tocotrienol (α-TCT) is a member of the vitamin E family. It has been reported to protect the brain against various pathologies including cerebral ischemia and neurodegeneration. However, it is still unclear if α-TCT exhibits beneficial effects during brain development. We hypothesized that treatment with α-TCT improves intracellular redox homeostasis supporting normal development of neurons. We found that primary hippocampal neurons isolated from rat feti grown in α-TCT-containing media achieved greater levels of neurite complexity compared to ethanol-treated control neurons. Neurons were treated with 1 μM α-TCT for 3 weeks, and media were replaced with fresh α-TCT every week. Treatment with α-TCT increased α-TCT levels (26 pmol/mg protein) in the cells, whereas the control neurons did not contain α-TCT. α-TCT-treated neurons produced adenosine triphosphate (ATP) at a higher rate and increased ATP retention at neurites, supporting formation of neurite branches. Although treatment with α-TCT alone did not change neuronal viability, neurons grown in α-TCT were more resistant to death at maturity. We further found that messenger RNA and protein levels of B-cell lymphoma-extra large (Bcl-xL) are increased by α-TCT treatment without inducing posttranslational cleavage of Bcl-xL. Bcl-xL is known to enhance mitochondrial energy production, which improves neuronal function including neurite outgrowth and neurotransmission. Therefore α-TCT-mediated Bcl-xL upregulation may be the central mechanism of neuroprotection seen in the α-TCT-treated group. In summary, treatment with α-TCT upregulates Bcl-xL and increases ATP levels at neurites. This correlates with increased neurite branching during development and with protection of mature neurons against oxidative stress.

Improving CAR T-Cell Persistence

Over the last decade remarkable progress has been made in enhancing the efficacy of CAR T therapies. However, the clinical benefits are still limited, especially in solid tumors. Even in hematological settings, patients that respond to CAR T therapies remain at risk of relapsing due to several factors including poor T-cell expansion and lack of long-term persistence after adoptive transfer. This issue is even more evident in solid tumors, as the tumor microenvironment negatively influences the survival, infiltration, and activity of T-cells. Limited persistence remains a significant hindrance to the development of effective CAR T therapies due to several determinants, which are encountered from the cell manufacturing step and onwards. CAR design and ex vivo manipulation, including culture conditions, may play a pivotal role. Moreover, previous chemotherapy and lymphodepleting treatments may play a relevant role. In this review, the main causes for decreased persistence of CAR T-cells in patients will be discussed, focusing on the molecular mechanisms underlying T-cell exhaustion. The approaches taken so far to overcome these limitations and to create exhaustion-resistant T-cells will be described. We will also examine the knowledge gained from several key clinical trials and highlight the molecular mechanisms determining T-cell stemness, as promoting stemness may represent an attractive approach to improve T-cell therapies.

An Updated Comprehensive Review on Vitamin A and Carotenoids in Breast Cancer: Mechanisms, Genetics, Assessment, Current Evidence, and Future Clinical Implications

Vitamin A and carotenoids are fat-soluble micronutrients that play important role as powerful antioxidants modulating oxidative stress and cancer development. Breast cancer is the most common malignancy in women. As the risk of breast cancer is dependent on various lifestyle factors such as dietary modifications, there is increasing interest surrounding the anti-cancerous properties of vitamin A and carotenoids. Despite the suggested protective roles of vitamin A and carotenoids in breast cancer development, their clinical application for the prevention and treatment of breast cancer is limited. In this narrative review, we discuss the roles of vitamin A and carotenoids along with the evaluation method of vitamin A status. We also exhibit the association of genetic variations involved in metabolism of vitamin A and carotenoids with cancers and other diseases. We demonstrate the epidemiological evidence for the relationship of vitamin A and carotenoids with breast cancer risk, their effects on cancer mechanism, and the recent updates in clinical practice of vitamin A or carotenoids as a potential therapeutic agent against breast cancer. This review provides insight into the preventive and therapeutic roles of vitamin A and carotenoids in breast cancer development and progression.

The Akt-mTORC1 pathway mediates Axl receptor tyrosine kinase-induced mesangial cell proliferation

Glomerulonephritis (GN), an important pathologic feature of many renal diseases, is frequently characterized by mesangial cell proliferation. We and others have previously shown that the TAM family receptor tyrosine kinases Axl, Mer, and Tyro-3 contribute to cell survival, proliferation, migration, and clearance of apoptotic cells (ACs); that Axl contributes to GN by promoting mesangial cell proliferation; and that small molecule inhibition of Axl ameliorates nephrotoxic serum-induced GN in mice. We now show that stimulation of renal mesangial cell Axl causes a modest increase in intracellular Ca²⁺ and activates NF-κB, mTOR, and the mTOR-containing mTORC1 complex, which phosphorylates the ribosomal protein S6. Axl-induction of Akt activation is upstream of NF-κB and mTOR activation, which are mutually codependent. Axl-induced NF-κB activation leads to Bcl-xl up-regulation. Axl is more important than Mer at mediating AC phagocytosis by mesangial cells, but less important than Mer at mediating phagocytosis of ACs by peritoneal macrophages. Taken together, our data suggest the possibility that Axl mediates mesangial cell phagocytosis of ACs and promotes mesangial cell proliferation by activating NF-κB and mTORC1.

MicroRNAs in shaping the resolution phase of inflammation

Inflammation is a host defense mechanism orchestrated through imperative factors - acute inflammatory responses mediated by cellular and molecular events leading to activation of defensive immune subsets - to marginalize detrimental injury, pathogenic agents and infected cells. These potent inflammatory events, if uncontrolled, may cause tissue damage by perturbing homeostasis towards immune dysregulation. A parallel host mechanism operates to contain inflammatory pathways and facilitate tissue regeneration. Thus, resolution of inflammation is an effective moratorium on the pro-inflammatory pathway to avoid the tissue damage inside the host and leads to reestablishment of tissue homeostasis. Dysregulation of the resolution pathway can have a detrimental impact on tissue functionality and contribute to the diseased state. Multiple reports have suggested peculiar dynamics of miRNA expression during various pro- and anti-inflammatory events. The roles of miRNAs in the regulation of immune responses are well-established. However, understanding of miRNA regulation of the resolution phase of events in infection or wound healing models, which is sometimes misconstrued as anti-inflammatory signaling, remains limited. Due to the deterministic role of miRNAs in pro-inflammatory and anti-inflammatory pathways, in this review we have provided a broad perspective on the putative role of miRNAs in the resolution of inflammation and explored their imminent role in therapeutics.

The Hallmarks of Flavonoids in Cancer

Flavonoids represent an important group of bioactive compounds derived from plant-based foods and beverages with known biological activity in cells. From the modulation of inflammation to the inhibition of cell proliferation, flavonoids have been described as important therapeutic adjuvants against several diseases, including diabetes, arteriosclerosis, neurological disorders, and cancer. Cancer is a complex and multifactor disease that has been studied for years however, its prevention is still one of the best known and efficient factors impacting the epidemiology of the disease. In the molecular and cellular context, some of the mechanisms underlying the oncogenesis and the progression of the disease are understood, known as the hallmarks of cancer. In this text, we review important molecular signaling pathways, including inflammation, immunity, redox metabolism, cell growth, autophagy, apoptosis, and cell cycle, and analyze the known mechanisms of action of flavonoids in cancer. The current literature provides enough evidence supporting that flavonoids may be important adjuvants in cancer therapy, highlighting the importance of healthy and balanced diets to prevent the onset and progression of the disease.

15-Deoxy-△12,14-Prostaglandin J2 Promotes Resolution of Experimentally Induced Colitis

Uncontrolled macrophage functions cause failure to resolve gut inflammation and has been implicated in the pathogenesis of inflammatory bowel disease (IBD). 15-Deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂), one of endogenous lipid mediators formed from arachidonic acid during the inflammatory process, has been reported to terminate inflammation. However, the pro-resolving effect of 15d-PGJ₂ on intestinal inflammation and underlying molecular mechanisms remain largely unknown. In the present study, we examined the effects of 15d-PGJ₂ on the resolution of dextran sulfate sodium (DSS)-induced murine colitis that mimics human IBD. Pharmacologic inhibition of prostaglandin D synthase (PGDS) responsible for the synthesis of 15d-PGJ₂ hampered resolution of inflammation in the colonic mucosa of mice treated with DSS. Notably, intraperitoneal injection of 15d-PGJ₂ accelerated the resolution of experimentally induced colitis. 15d-PGJ₂ treatment reduced the number of neutrophils and M1 macrophages, while it increased the proportion of M2 macrophages. Moreover, 15d-PGJ₂ treated mice exhibited the significantly reduced proportion of macrophages expressing the pro-inflammatory cytokine, IL-6 with concomitant suppression of STAT3 phosphorylation in the colonic mucosa of mice administered 2.5% DSS in drinking water. Taken together, these findings clearly indicate that 15d-PGJ₂, endogenously generated from arachidonic acid by cyclooxygenase-2 and PGDS activities in inflamed tissue, promotes resolution of intestinal colitis.

Methyl lucidone induces apoptosis and G2/M phase arrest via the PI3K/Akt/NF-κB pathway in ovarian cancer cells

Context: Methyl lucidone (ML) from the dried fruit of Lindera erythrocarpa Makino (Lauraceae) exhibits cytotoxic effects in various cancer cell lines. However, its effects on ovarian cancer cells remain unknown.Objective: This study evaluates the mechanism of ML-induced apoptosis, cell cycle distribution in ovarian cells.Materials and methods: The cytotoxic effect of ML (2.5-80 µM) on OVCAR-8 and SKOV-3 cells was evaluated by MTS assay for 24 and 48 h. Apoptosis and cell cycle arrest were analysed by flow cytometry. PCR, western blot analyses were performed to examine the related signalling pathways.Results: ML induced significant cellular morphological changes and apoptosis in ovarian cancer cells, leading to an antiproliferative effect (IC₅₀ = 33.3-54.7 µM for OVCAR-8 and 48.8-60.7 µM for SKOV-3 cells). Treatment with ML induced cleavage of caspase-3/9 and PARP and release of cytochrome c from the mitochondria. Moreover, ML downregulated the expression of Bcl-2 and Bcl-xL and induced cell cycle arrest in the G₂/M phase. Additionally, ML suppressed the expression of cyclin-A/B and promoted that of the cyclin-dependent kinase inhibitors p21 and p27. The expression of death receptors was not altered. Interestingly, ML also inhibited the activity of PI3K/Akt and NF-κB.Discussion and conclusions: ML caused G₂/M phase arrest and apoptosis in ovarian cancer cells by activating intrinsic apoptotic pathways and suppressing the PI3K/Akt survival pathway. ML may be a potential anticancer agent to suppress ovarian cancer proliferation; thus, to improve the survival rate of cancer patients.

NF-κB and Extrinsic Cell Death Pathways - Entwined Do-or-Die Decisions for T cells

NF-κB signaling is required at multiple stages of T cell development and function. The NF-κB pathway integrates signals from many receptors and involves diverse adapters and kinases. Recent advances demonstrate that kinases controlling NF-κB activation, such as the IKK complex, serve dual independent functions because they also control cell death checkpoints. Survival functions previously attributed to NF-κB are in fact mediated by these upstream kinases by novel mechanisms. This new understanding has led to a refined view of how NF-κB and cell death signaling are interlinked and how they regulate cell fate. We discuss how NF-κB activation and control of cell death signaling by common upstream triggers cooperate to regulate different aspects of T cell development and function.

Cellular Mechanisms of Circulating Tumor Cells During Breast Cancer Metastasis

Circulating tumor cells (CTCs) are cancer cells that detach from the primary site and travel in the blood stream. A higher number of CTCs increases the risk of breast cancer metastasis, and it is inversely associated with the survival rates of patients with breast cancer. Although the numbers of CTCs are generally low and the majority of CTCs die in circulation, the survival of a few CTCs can seed the development of a tumor at a secondary location. An increasing number of studies demonstrate that CTCs undergo modification in response to the dynamic biophysical environment in the blood due in part to fluid shear stress. Fluid shear stress generates reactive oxygen species (ROS), triggers redox-sensitive cell signaling, and alters the function of intracellular organelles. In particular, the mitochondrion is an important target organelle in determining the metastatic phenotype of CTCs. In healthy cells, mitochondria produce adenosine triphosphate (ATP) via oxidative phosphorylation in the electron transport chain, and during oxidative phosphorylation, they produce physiological levels of ROS. Mitochondria also govern death mechanisms such as apoptosis and mitochondrial permeability transition pore opening to, in order eliminate unwanted or damaged cells. However, in cancer cells, mitochondria are dysregulated, causing aberrant energy metabolism, redox homeostasis, and cell death pathways that may favor cancer invasiveness. In this review, we discuss the influence of fluid shear stress on CTCs with an emphasis on breast cancer pathology, then discuss alterations of cellular mechanisms that may increase the metastatic potentials of CTCs.

The Immuno-Modulatory Effects of Inhibitor of Apoptosis Protein Antagonists in Cancer Immunotherapy

One of the hallmarks of cancer cells is their ability to evade cell death via apoptosis. The inhibitor of apoptosis proteins (IAPs) are a family of proteins that act to promote cell survival. For this reason, upregulation of IAPs is associated with a number of cancer types as a mechanism of resistance to cell death and chemotherapy. As such, IAPs are considered a promising therapeutic target for cancer treatment, based on the role of IAPs in resistance to apoptosis, tumour progression and poor patient prognosis. The mitochondrial protein smac (second mitochondrial activator of caspases), is an endogenous inhibitor of IAPs, and several small molecule mimetics of smac (smac-mimetics) have been developed in order to antagonise IAPs in cancer cells and restore sensitivity to apoptotic stimuli. However, recent studies have revealed that smac-mimetics have broader effects than was first attributed. It is now understood that they are key regulators of innate immune signalling and have wide reaching immuno-modulatory properties. As such, they are ideal candidates for immunotherapy combinations. Pre-clinically, successful combination therapies incorporating smac-mimetics and oncolytic viruses, as with chimeric antigen receptor (CAR) T cell therapy, have been reported, and clinical trials incorporating smac-mimetics and immune checkpoint blockade are ongoing. Here, the potential of IAP antagonism to enhance immunotherapy strategies for the treatment of cancer will be discussed.

Curcuma raktakanda Induces Apoptosis and Suppresses Migration in Cancer Cells: Role of Reactive Oxygen Species

Although over 100 species of Curcuma are reported, only Curcuma longa is extensively studied. Curcuma raktakanda, a poorly studied species, is most commonly distributed in the Kerala state of India. For the first time, we examined the efficacy of different fractions (acetone, hexane, and ethyl acetate) of C. raktakanda against glioma, cervical, and breast cancer cell lines. As determined by mitochondrial reductase activity assay, the viability of cancer cells was decreased in a concentration-dependent manner by the three fractions. The half maximal inhibitory concentration (IC-50) values after the treatment of C-6 glioma cells for 48 h was found to be 32.97 µg/mL (acetone extract), 40.63 µg/mL (hexane extract), and 51.65 µg/mL (ethyl acetate extract). Of the three fractions, the acetone fraction was more effective. The long-term colony formation of cancer cells was significantly suppressed by the acetone fraction. Analyses using DAPI (4',6-diamidino-2-phenylindole) staining, AO/PI (acridine orange/propidium iodide) staining, DNA laddering, and sub-G1 population revealed that the acetone extract induced apoptosis in glioma cells. The extract induced reactive oxygen species generation and suppressed the expression of cell survival proteins. The migration of cancer cells was also suppressed by the acetone extract. The gas chromatography-mass spectrometry (GC-MS) analysis indicated that tetracontane, dotriacontane, hexatriacontane, pentacosane, hexacosane, and eicosane are the major components in the acetone extract. Collectively, the extract from C. raktakanda exhibited anti-carcinogenic activities in cancer cells. We are exploring whether the phytoconstituents, individually, or collectively contribute to the anti-cancer activities of C. raktakanda.

Aryl hydrocarbon receptor activation modulates γδ intestinal intraepithelial lymphocytes and protects against ischemia/reperfusion injury in the murine small intestine

The pathogenesis of intestinal ischemia/reperfusion (I/R) is associated with dysregulation of the intestinal immune system. The aryl hydrocarbon receptor (AhR), a receptor expressed in gamma‑delta (γδ) intraepithelial lymphocytes (IELs), is thought to regulate inflammation in the bowel. γδIELs are a key immunologic compartment with a capacity to modulate immune responses. In the present study, the function of the AhR in γδIELs in a mouse model of intestinal I/R injury was investigated to determine whether the AhR attenuates intestinal injury induced by intestinal I/R. Mice were assigned to three groups: sham, I/R and I/R+6‑formylindolo(3,2‑b)carbazole (FICZ). The sham group received no ischemia treatment, whereas the I/R and I/R+FICZ groups underwent upper mesenteric vessel ischemia for 30 min. The I/R group was injected intraperitoneally with 0.3 ml saline and the I/R+FICZ group was administered 1 µg of FICZ before a subsequent 6 h reperfusion. Then, the mice were sacrificed and the entire small intestinal tissues were collected for histologic examination. The phenotype and apoptosis of γδIELs and activation of CD4+ and CD8+ IELs were examined using flow cytometry. The cytokine mRNA and anti‑apoptosis gene expression in IELs were measured by qPCR. FICZ increased the γδIEL population and anti‑apoptosis genes in the γδIELs. FICZ reduced the percentage of activated CD4+ and CD8+ subpopulations and the expression of pro‑inflammatory mediator genes in IELs. FICZ inhibited inflammation in the gastrointestinal tract of mice with I/R injury. These results suggest that the AhR plays an important role in protecting the small intestine from I/R and increasing the γδIEL population by decreasing apoptosis of γδIELs.

STAT3 enhances the constitutive activity of AGC kinases in melanoma by transactivating PDK1

Background

The PI3K/Akt and the STAT3 pathways are functionally associated in many tumor types. Both in vitro and in vivo studies have revealed that either biochemical or genetic manipulation of the STAT3 pathway activity induce changes in the same direction in Akt activity. However, the implicated mechanism has been poorly characterized. Our goal was to characterize the precise mechanism linking STAT3 with the activity of Akt and other AGC kinases in cancer using melanoma cells as a model.

Results

We show that active STAT3 is constitutively bound to the PDK1 promoter and positively regulate PDK1 transcription through two STAT3 responsive elements. Transduction of WM9 and UACC903 melanoma cells with STAT3-small hairpin RNA decreased both PDK1 mRNA and protein levels. STAT3 knockdown also induced a decrease of the phosphorylation of AGC kinases Akt, PKC, and SGK. The inhibitory effect of STAT3 silencing on Akt phosphorylation was restored by HA-PDK1. Along this line, HA-PDK1 expression significantly blocked the cell death induced by dacarbazine plus STAT3 knockdown. This effect might be mediated by Bcl2 proteins since HA-PDK1 rescued Bcl2, Bcl-XL, and Mcl1 levels that were down-regulated upon STAT3 silencing.

Conclusions

We show that PDK1 is a transcriptional target of STAT3, linking STAT3 pathway with AGC kinases activity in melanoma. These data provide further rationale for the ongoing effort to therapeutically target STAT3 and PDK1 in melanoma and, possibly, other malignancies.

Electronic supplementary material

The online version of this article (10.1186/s13578-018-0265-8) contains supplementary material, which is available to authorized users.

Estrogen deficiency exacerbates Aβ-induced memory impairment through enhancement of neuroinflammation, amyloidogenesis and NF-ĸB activation in ovariectomized mice

Estrogen is well known to have a preventative effect in Alzheimer's disease (AD) pathology. Several studies have demonstrated that nuclear factor kappa-B (NF-ĸB) can contribute to the effects of estrogen on the development of AD. We investigated whether NF-ĸB affects amyloid-beta (Aβ)-induced memory impairment in an estrogen-lacking condition. In the present study, nine-week-old Institute cancer research (ICR) mice were ovariectomized to block estrogen stimulation. Ten weeks after the ovariectomization, mice were administered with Aβ (300 pmol) via intracerebroventricular (ICV) infusion for 2 weeks. Memory impairment, neuroinflammatory protein expression, and amyloidogenic pathways were then measured. Ovariectomized mice demonstrated severe memory impairment, Aβ accumulation, neprilysin downregulation, and activation of NF-ĸB signaling compared to sham-control mice. In vitro experiments demonstrated that β-estradiol (10 μM) inhibited Aβ (1 μM)-induced neuroinflammation in microglial BV-2 cells and prevented Aβ-induced cell death in primary cultured neuronal cells. As in in vivo experiments, NF-ĸB activation was significantly upregulated in in vitro experiments. Furthermore β-estradiol treatment inhibited NF-ĸB activation in both of microglial BV-2 cells and cultured neuronal cells. These findings suggest that estrogen may protect against memory impairment through the regulation of Aβ accumulation and neurogenic inflammation by inhibiting NF-κB activity.

Enhanced survival of BCG-stimulated dendritic cells: involvement of anti-apoptotic proteins and NF-κB

BCG (Bacillus Calmette-Guérin) is the only available vaccine against TB and is also used for the treatment of superficial bladder cancer. BCG-mediated protection against TB and bladder cancer has been shown to rely on its ability to induce superior CD4⁺ and CD8⁺ T cell responses. As the magnitude of T cell responses is defined by dendritic cell (DC) lifespan, we examined the effect of BCG on DC survival and its underlying mechanisms. It was observed that BCG stimulation enhanced DC survival and prolonged DC lifespan in a dose-dependent manner. Live BCG led to a higher DC survival compared with heat-killed BCG. FITC-Annexin V staining showed that BCG promoted DC survival by inhibiting apoptosis. Consistently, higher expressions of anti-apoptotic proteins Bcl-2 and Bcl-x_L were observed in BCG-stimulated DCs. Pharmacological inhibition of Bcl-2 and Bcl-x_L drastically reduced the DC survival efficacy of BCG. Comparable survival of BCG-stimulated wild-type and MyD88^−/− DCs suggested that MyD88 signaling is dispensable for BCG-induced DC survival. NF-κB is one of the key regulators of innate immune responses. We observed that pharmacological inhibition of NF-κB abrogated BCG-mediated increase in DC survival and expression of anti-apoptotic proteins. These findings provide a novel insight into the effect of BCG on DC physiology.

Summary: BCG enhanced the survival of dendritic cells (DCs) and prolonged their lifespan. BCG promoted DC survival by up-regulating Bcl-2 and Bcl-x_L. Increased survival of BCG-stimulated DCs was dependent on NF-κB, but was independent of MyD88 signaling.

Immunotoxicity of ochratoxin A and aflatoxin B1 in combination is associated with the nuclear factor kappa B signaling pathway in 3D4/21 cells

The co-contamination of cereals, grains, crops, and animal feeds by mycotoxins is a universal problem. Humans and animals are exposed to several mycotoxins simultaneously as evidenced by extensive studies on this topic. Yet, most studies have addressed the effects of mycotoxins individually. Aflatoxin B1 and ochratoxin A can induce immunotoxicity. However, it remains unclear whether a combination of these mycotoxins aggravates immunotoxicity and the potential mechanism underlying this effect. In this study, we used the cell line 3D4/21, swine alveolus macrophages and innate immune cell. The results showed that the percentage of cell inhibition, annexin V/PI-positive rates, and the expression of pro-inflammatory cytokines (tumor necrosis factor alpha and interleukin-6) significantly increased and the release of lactate dehydrogenase and phagocytotic index were significantly decreased at different concentrations of aflatoxin B1 and ochratoxin A combination when compared with control. The combination of aflatoxin B1 and ochratoxin A significantly decreased the production of GSH and increased reactive oxygen species level. However, N-acetylcysteine suppressed the oxidative stress and alleviated the immunotoxicity induced by the combination. The combination of aflatoxin B1 and ochratoxin A markedly enhanced the degradation of IκBa, the phosphorylation of nuclear factor kappa B (p65), and the translocation of activated nuclear factor kappa B (NF-κB) into the nuclei as demonstrated by western blotting and confocal laser scanning microscopy. These effects could be reversed by BAY 11-7082, a specific inhibitor of NF-κB. Taken together, a combination of aflatoxin B1 and ochratoxin A could aggravate immunotoxicity by activating the NF-κB signaling pathway.

TNF-α induces human neural progenitor cell survival after oxygen-glucose deprivation by activating the NF-κB pathway

Neural progenitor cell (NPC) transplantation has been shown to be beneficial in the ischemic brain. However, the low survival rate of transplanted NPCs in an ischemic microenvironment limits their therapeutic effects. Tumor necrosis factor-alpha (TNF-α) is one of the proinflammatory cytokines involved in the pathogenesis of various injuries. On the other hand, several studies have shown that TNF-α influences the proliferation, survival, and differentiation of NPCs. Our study investigated the effect of TNF-α pretreatment on human NPCs (hNPCs) under ischemia-related conditions in vitro. hNPCs harvested from fetal brain tissue were pretreated with TNF-α before being subjected to oxygen–glucose deprivation (OGD) to mimic ischemia in vitro. TNF-α pretreatment improved the viability and reduced the apoptosis of hNPCs after OGD. At the molecular level, TNF-α markedly increased the level of NF-κB signaling in hNPCs, and an NF-κB pathway inhibitor, BAY11-7082, completely reversed the protective effects of TNF-α on hNPCs. These results suggest that TNF-α improves hNPC survival by activating the NF-κB pathway. In addition, TNF-α significantly enhanced the expression of cellular inhibitor of apoptosis 2 (cIAP2). Use of a lentivirus-mediated short hairpin RNA targeting cIAP2 mRNA demonstrated that cIAP2 protected against OGD-induced cytotoxicity in hNPCs. Our study of intracellular NF-κB signaling revealed that inhibition of NF-κB activity abolished the TNF-α-mediated upregulation of cIAP2 in hNPCs and blocked TNF-α-induced cytoprotection against OGD. Therefore, this study suggests that TNF-α pretreatment, which protects hNPCs from OGD-induced apoptosis by activating the NF-κB pathway, provides a safe and simple approach to improve the viability of transplanted hNPCs in cerebral ischemia.

A potent “survival signal” for brain stem cells could enable effective regenerative therapies for stroke patients. Neural progenitor cells (NPCs) can develop into functional neurons and supportive glial cells, and researchers are tantalized by the prospect of using NPCs to repair damaged brain tissue. NPCs generally fail to flourish after transplantation, but a team led by Kook In Park at Yonsei University College of Medicine, South Korea, have found a signaling factor that helps these cells to survive and divide. Tumor necrosis factor-α (TNF-α) is associated with inflammation, but also protects neurons after a stroke. The researchers showed that pretreatment with TNF-α preserved NPCs exposed to starvation and oxygen-deprivation conditions in cell culture by activating critical cell survival pathways. These findings suggest that TNF-α may enable NPCs to survive long enough to repair post-stroke neurological damage.

Lippia origanoides extract induces cell cycle arrest and apoptosis and suppresses NF-κB signaling in triple-negative breast cancer cells

Treatments targeting hormone receptors typically fail to provide a positive clinical outcome against triple-negative breast cancers (TNBC), which lack expression of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (Her2/neu). Towards identifying viable treatments for aggressive breast cancer, we have tested an extract of the tropical plant Lippia origanoides (LOE) on TNBC and normal cells lines to uncover its potential anticancer effects. Treatment with LOE reduced TNBC cell viability in a dose-dependent manner to a greater extent than in normal mammary epithelial MCF10A cells. In MDA-MB-231 cells, LOE was found to halt the cell cycle in the G0/G1 phase via cyclin D1 and cIAP2 regulation, and induce apoptosis without promoting necrosis via caspase-8/-3 and PARP cleavage. Constitutive nuclear factor-κB (NF-κB) signaling has been shown to contribute to the heightened inflammatory state and survival in TNBC cells. Herein, we also provide evidence that LOE inhibits NF-κB signaling by reducing RIP1 protein levels in MDA-MB-231 cells. These studies reveal that LOE suppresses key features of the progression of aggressive breast cancer cells and provides a basis for further definition of its underlying mechanisms of action and anticancer potential.

Lipid Mediators in Inflammation

Lipids are potent signaling molecules that regulate a multitude of cellular responses, including cell growth and death and inflammation/infection, via receptor-mediated pathways. Derived from polyunsaturated fatty acids (PUFAs), such as arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), each lipid displays unique properties, thus making their role in inflammation distinct from that of other lipids derived from the same PUFA. This diversity arises from their synthesis, which occurs via discrete enzymatic pathways and because they elicit responses via different receptors. This review will collate the bioactive lipid research to date and summarize the major pathways involved in their biosynthesis and role in inflammation. Specifically, lipids derived from AA (prostanoids, leukotrienes, 5-oxo-6,8,11,14-eicosatetraenoic acid, lipoxins, and epoxyeicosatrienoic acids), EPA (E-series resolvins), and DHA (D-series resolvins, protectins, and maresins) will be discussed herein.

T11TS immunotherapy repairs PI3K-AKT signaling in T-cells: Clues toward enhanced T-cell survival in rat glioma model

Malignant glioma is the most fatal of astrocytic lineage tumors despite therapeutic advances. Onset and progression of gliomas is accompanied by severe debilitation of T-cell defense and T-cell survival. One of the chief contributors to T-cell survival downstream of activation is the PI3K-AKT pathway. Our prior studies showed that the novel immunotherapeutic molecule T11-target structure (T11TS) blocks T-cell apoptosis in glioma. We also showed activation of immunological synapse components and calcineurin-NFAT pathway following T11TS immunotherapy of glioma-bearing rats. This lead to investigations whether such T-cell activation upon T11TS therapy translates into activation of downstream PI3K/AKT signals which may be related to observed blockade of T-cell apoptosis. For the purpose, we assessed by flowcytometry and immunoblotting, expressions of PI3K, PDK1, AKT, p-AKT, and PTEN in splenic T-cells of normal, experimentally-induced glioma-bearing rats and glioma-bearing rats receiving first, second and third doses of T11TS. We also determined comparative nuclear translocation of NF-κB across groups. We found significant increases in T-cell expressions of PDK1, PI3K, and p-AKT in T11TS-treated animal groups compared to sharp downregulations in glioma. AKT levels remained unchanged across groups. PTEN levels declined sharply after T11TS immunotherapy. T11TS also caused enhanced NF-κB translocation to the T-cell nucleus compared to glioma group. Results showed heightened activation of the PI3K-AKT pathway in glioma-bearing rats following T11TS immunotherapy. These results illustrate the novel role of T11TS immunotherapy in ameliorating the PI3K pathway in T-cells in glioma-bearing animals to enhance T-cell survival, according greater defense against glioma. The study thus has far-reaching clinical outcomes.

Microenvironmental agonists generate de novo phenotypic resistance to combined ibrutinib plus venetoclax in CLL and MCL

De novo resistance and rapid recurrence often characterize responses of B-cell malignancies to ibrutinib (IBR), indicating a need to develop drug combinations that block compensatory survival signaling and give deeper, more durable responses. To identify such combinations, we previously performed a combinatorial drug screen and identified the Bcl-2 inhibitor venetoclax (VEN) as a promising partner for combination with IBR in Mantle Cell Lymphoma (MCL). We have opened a multi-institutional clinical trial to test this combination. However, analysis of primary samples from patients with MCL as well as chronic lymphocytic leukemia (CLL) revealed unexpected heterogeneous de novo resistance even to the IBR+VEN combination. In the current study, we demonstrate that resistance to the combination can be generated by microenvironmental agonists: IL-10, CD40L and, most potently, CpG-oligodeoxynucleotides (CpG-ODN), which is a surrogate for unmethylated DNA and a specific agonist for TLR9 signaling. Incubation with these agonists caused robust activation of NF-κB signaling, especially alternative NF-κB, which led to enhanced expression of the anti-apoptotic proteins Mcl-1, Bcl-xL, and survivin, thus decreasing dependence on Bcl-2. Inhibitors of NF-κB signaling blocked overexpression of these anti-apoptotic proteins and overcame resistance. Inhibitors of Mcl-1, Bcl-xL, or survivin also overcame this resistance, and showed synergistic benefit with the IBR+VEN combination. We conclude that microenvironmental factors, particularly the TLR9 agonist, can generate de novo resistance to the IBR+VEN combination in CLL and MCL cells. This signaling pathway presents targets for overcoming drug resistance induced by extrinsic microenvironmental factors in diverse B-cell malignancies.

Defects in CD4+ T cell LFA-1 integrin-dependent adhesion and proliferation protect Cd47-/- mice from EAE

CD47 is known to play an important role in CD4⁺ T cell homeostasis. We recently reported a reduction in mice deficient in the Cd47 gene (Cd47^-/-) CD4⁺ T cell adhesion and transendothelial migration (TEM) in vivo and in vitro as a result of impaired expression of high-affinity forms of LFA-1 and VLA-4 integrins. A prior study concluded that Cd47^-/- mice were resistant to experimental autoimmune encephalomyelitis (EAE) as a result of complete failure in CD4⁺ T cell activation after myelin oligodendrocyte glycoprotein peptide 35-55 aa (MOG_35-55) immunization. As the prior EAE study was published before our report, authors could not have accounted for defects in T cell integrin function as a mechanism to protect Cd47^-/- in EAE. Thus, we hypothesized that failure of T cell activation involved defects in LFA-1 and VLA-4 integrins. We confirmed that Cd47^-/- mice were resistant to MOG_35-55-induced EAE. Our data, however, supported a different mechanism that was not a result of failure of CD4⁺ T cell activation. Instead, we found that CD4⁺ T cells in MOG_35-55-immunized Cd47^-/- mice were activated, but clonal expansion contracted within 72 h after immunization. We used TCR crosslinking and mitogen activation in vitro to investigate the underlying mechanism. We found that naïve Cd47^-/- CD4⁺ T cells exhibited a premature block in proliferation and survival because of impaired activation of LFA-1, despite effective TCR-induced activation. These results identify CD47 as an important regulator of LFA-1 and VLA-4 integrin-adhesive functions in T cell proliferation, as well as recruitment, and clarify the roles played by CD47 in MOG_35-55-induced EAE.

Dietary glutamine supplementation enhances endothelial progenitor cell mobilization in streptozotocin-induced diabetic mice subjected to limb ischemia

Diabetes is a metabolic disorder with increased risk of vascular diseases. Tissue ischemia may occur with diabetic vascular complications. Bone marrow-derived endothelial progenitor cells (EPCs) constitute a reparative response to ischemic injury. This study investigated the effects of oral glutamine (GLN) supplementation on circulating EPC mobilization and expression of tissue EPC-releasing markers in diabetic mice subjected to limb ischemia. Diabetes was induced by a daily intraperitoneal injection of streptozotocin for 5 days. Diabetic mice were divided into 2 nonischemic groups and 6 ischemic groups. One of the nonischemic and 3 ischemic groups were fed the control diet, while the remaining 4 groups received diets with identical components except that part of the casein was replaced by GLN. The respective diets were fed to the mice for 3 weeks, and then the nonischemic mice were sacrificed. Unilateral hindlimb ischemia was created in the ischemic groups, and mice were sacrificed at 1, 7 or 21 days after ischemia. Their blood and ischemic muscle tissues were collected for further analyses. Results showed that plasma matrix metallopeptidase (MMP)-9 and the circulating EPC percentage increased after limb ischemia in a diabetic condition. Compared to groups without GLN, GLN supplementation up-regulated plasma stromal cell-derived factor (SDF)-1 and muscle MMP-9, SDF-1, hypoxia-inducible factor-1 and vascular endothelial growth factor gene expression. The CD31-immunoreactive intensities were also higher in the ischemic limb. These findings suggest that GLN supplementation enhanced circulating EPC mobilization that may promote endothelium repair at ischemic tissue in diabetic mice subjected to limb ischemia.

Glutamine Modulates Changes in Intestinal Intraepithelial γδT-Lymphocyte Expressions in Mice With Ischemia/Reperfusion Injury

This study investigated the effect of glutamine (GLN) on expressions of small intestinal intraepithelial lymphocyte (IEL) γδT-cell proinflammatory cytokines and apoptotic regulatory factor genes in a mouse model of hindlimb ischemia/reperfusion (IR) injury. Mice were assigned to a normal control group and three IR groups. Mice in the normal control group received no ischemia treatment, whereas IR groups had hindlimb ischemia for 90 min with subsequent 0 (IR0) or 24 h (IR24) of reperfusion. The IR0 group was sacrificed immediately after reperfusion. The IR24S group was injected with saline, and the IR24G group was given 0.75 g GLN/kg of body weight once via a tail vein before reperfusion. The IR24 groups were sacrificed 24 h after reperfusion. Small intestinal IEL γδT cells of the animals were isolated for further analysis. Results showed that IR injury resulted in lower small intestinal IEL γδT-cell percentages and higher proinflammatory cytokine messenger RNA expressions of interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α by IEL γδT cells. Compared with the IR24S group, the IR24G group had a higher IEL γδT-cell percentage. Multiples of change of messenger RNA of proliferation gene expressions of the antiapoptotic Bcl-xl (B-cell lymphoma-extra large) and IL-7 receptor in the IR24G group were higher, whereas expressions of the keratinocyte growth factor and bacterial lectin regenerating islet-derived (Reg)IIIγ were lower in IEL γδT cells. Histological findings also showed that damage to the intestinal mucosa was less severe in the IR group with GLN. These results indicated that a single dose of GLN administered before reperfusion maintained small intestinal IEL γδT cell populations and reduced expressions of intestinal inflammatory cytokines, which may have consequently ameliorated the severity of IR-induced small intestinal epithelial injury.

PACS-2 mediates the ATM and NF-κB-dependent induction of anti-apoptotic Bcl-xL in response to DNA damage

Nuclear factor kappa B (NF-κB) promotes cell survival in response to genotoxic stress by inducing the expression of anti-apoptotic proteins including Bcl-xL, which protects mitochondria from stress-induced mitochondrial outer membrane permeabilization (MOMP). Here we show that the multifunctional sorting protein Pacs-2 (phosphofurin acidic cluster sorting protein-2) is required for Bcl-xL induction following DNA damage in primary mouse thymocytes. Consequently, in response to DNA damage, Pacs-2(-/-) thymocytes exhibit a blunted induction of Bcl-xL, increased MOMP and accelerated apoptosis. Biochemical studies show that cytoplasmic PACS-2 promotes this DNA damage-induced anti-apoptotic pathway by interacting with ataxia telangiectasia mutated (ATM) to drive NF-κB activation and induction of Bcl-xL. However, Pacs-2 was not required for tumor necrosis factor-α-induced NF-κB activation, suggesting a role for PACS-2 selectively in NF-κB activation in response to DNA damage. These findings identify PACS-2 as an in vivo mediator of the ATM and NF-κB-dependent induction of Bcl-xL that promotes cell survival in response to DNA damage.

Acceleration of amyloidogenesis and memory impairment by estrogen deficiency through NF-κB dependent beta-secretase activation in presenilin 2 mutant mice

Nearly 7-10 million people are living with Alzheimer's disease (AD) worldwide. Senile plaques composed of β-amyloid (Aβ) are a pathological hallmark of Alzheimer's disease. Presenilin 2 (PS2) mutations increase Aβ generation in the brains of AD patients. The Aβ is generated through the sequential cleavage of amyloid precursor protein by β- and γ-secretases. Additionally, increasing evidences suggest that estrogen can reduce the development of AD via regulation of β-secretases activity and beta-site APP-cleaving enzyme (BACE1) expression. But the underlying correlation mechanism of Aβ generation by PS2 mutations and estrogen remains to be clarified. To investigate the anti-amyloidogenesis effect of estrogen in a PS2 mutative condition, we examined memory impairment in ovariectomized PS2 mutation (N141I) mice in which cognitive function was assessed by the Morris water maze test and passive avoidance test. In addition, Western blot analysis, immunostaining, immunofluorescence staining, ELISA and enzyme activity assays were used to examine the degree of Aβ deposition in the brains. In the present study, Aβ accumulated more in the ovariectomized PS2 mutant mice brain, and greatly worsened memory impairment and glial activation as well as neurogenic inflammation. In parallel with increased memory impairment, activity of β-secretase and expression of the BACE1 increased inovariectomized PS2 mutant mice. Much higher activity of NF-κB was observed by EMSA in ovariectomized PS2 mutant mice. In addition, the Aβ level was decreased by treatment of β-estradiol through inhibiting BACE1 expression in PS2 transfacted PC12 cells. These results suggest that mutation of PS2 can lead to NF-κB mediate amyloidogensis, and this effect can be amplified by the absence of estrogen.

NF-κB Essential Modulator (NEMO) Is Critical for Thyroid Function

The I-κB kinase (IKK) subunit NEMO/IKKγ (NEMO) is an adapter molecule that is critical for canonical activation of NF-κB, a pleiotropic transcription factor controlling immunity, differentiation, cell growth, tumorigenesis, and apoptosis. To explore the functional role of canonical NF-κB signaling in thyroid gland differentiation and function, we have generated a murine strain bearing a genetic deletion of the NEMO locus in thyroid. Here we show that thyrocyte-specific NEMO knock-out mice gradually develop hypothyroidism after birth, which leads to reduced body weight and shortened life span. Histological and molecular analysis indicate that absence of NEMO in thyrocytes results in a dramatic loss of the thyroid gland cellularity, associated with down-regulation of thyroid differentiation markers and ongoing apoptosis. Thus, NEMO-dependent signaling is essential for normal thyroid physiology.

CD28 co-stimulation in T-cell homeostasis: a recent perspective

T-cells play a key role within the adaptive immune system mediating cellular immunity and orchestrating the immune response as a whole. Their activation requires not only recognition of antigen/major histocompatibility complexes by the T-cell receptor but in addition co-stimulation via the CD28 molecule through binding to CD80, CD86, or as recently discovered, inducible co-stimulator ligand expressed by antigen-presenting cells. Apart from tight control of the co-stimulatory signal by the T-cell receptor complex, expression of the inhibitory receptor cytotoxic T-lymphocyte antigen-4 (CTLA-4) sharing its ligands with CD28 is required to avoid inappropriate or prolonged T-cell activation. CD4(+) Foxp3(+) regulatory T (Treg) cells, which are crucial inhibitors of autoimmunity, add another level of complexity in that they differ from conventional non-regulatory CD4(+) T-cells by strongly depending on CD28 signaling for their generation and homeostasis. Moreover, CTLA-4 is constitutively expressed by Treg cells where it serves as a key mediator of suppression, while conventional CD4(+) T-cells express CTLA-4 only after activation. Here, we discuss recent insights into the molecular events underlying CD28-mediated co-stimulation, its impact on gene regulation, and the differential role of CD28 expression on Treg cells versus conventional CD4(+) and CD8(+) T-cells. Moreover, we summarize the exciting therapeutic options which have arisen from our current understanding of T-cell co-stimulation. Some of these have already been translated into the clinic, while others are expected to follow soon due to promising preclinical results. In particular, we discuss the failed 2006 trial of the CD28 superagonist TGN1412, and the return of this potent T-cell activator to clinical development.

The role of thiopurine metabolites in inflammatory bowel disease and rheumatological disorders

Thiopurines have been a cornerstone of medical management of patients with inflammatory bowel disease(IBD) and many rheumatological disorders. The thiopurines are metabolized to their end products, 6-methymercaptopurine (6MMP) and the 6-thioguanine nucleotides (6TGN), with 6TGN being responsible for thiopurine efficacy by causing apoptosis and preventing activation and proliferation of T-lymphocytes. In IBD, conventional weight-based dosing with thiopurines leads to an inadequate response in many patients. Utilizing measurement of these metabolites and then employing dose optimization strategies has led to markedly improved outcomes in IBD. Switching between thiopurines as well as the addition of low-dose allopurinol can overcome adverse events and elevate 6TGN levels into the therapeutic window. There is a paucity of data on thiopurine metabolites in rheumatological diseases and further research is required.

IL-10/Janus kinase/signal transducer and activator of transcription 3 signaling dysregulates Bim expression in autoimmune lymphoproliferative syndrome

BACKGROUND

Autoimmune lymphoproliferative syndrome (ALPS) is a human disorder of T cell homeostasis caused by mutations that impair FAS-mediated apoptosis. A defining characteristic of ALPS is the expansion of double negative T cells (DNTC). Relatively little is known about how defective FAS-driven cell death and the Bcl-2 apoptotic pathway intersect in ALPS patients.

OBJECTIVE

We studied changes in Bcl-2 family member expression in ALPS to determine whether the Bcl-2 pathway might provide a therapeutic target.

METHODS

We used flow cytometry to analyze the expression of pro- and anti-apoptotic Bcl-2 family members in T cells from 12 ALPS patients and determined the in vitro sensitivity of ALPS DNTC to the pro-apoptotic BH3 mimetic, ABT-737.

RESULTS

The pro-apoptotic molecule, Bim, was significantly elevated in DNTC. Although no general pattern of individual anti-apoptotic Bcl-2 family members emerged, increased expression of Bim was always accompanied by increased expression of at least 1 anti-apoptotic Bcl-2 family member. Strikingly, Bim levels in DNTC correlated significantly with serum IL-10 in ALPS patients, and IL-10 was sufficient to mildly induce Bim in normal and ALPS T cells via a Janus kinase/signal transducer and activator of transcription 3-dependent mechanism. Finally, ABT-737 preferentially killed ALPS DNTC in vitro.

CONCLUSION

Combined, these data show that an IL-10/Janus kinase/signal transducer and activator of transcription 3 pathway drives Bim expression in ALPS DNTC, which renders them sensitive to BH3 mimetics, uncovering a potentially novel therapeutic approach to ALPS.

Green tea catechin, epigallocatechin-3-gallate, attenuates the cell viability of human non-small-cell lung cancer A549 cells via reducing Bcl-xL expression

Clinical and epidemiological studies have indicated that the consumption of green tea has a number of beneficial effects on health. Epigallocatechin-3-gallate (EGCg), the major polyphenolic compound present in green tea, has received much attention as an active ingredient. Among the numerous promising profiles of EGCg, the present study focused on the anticancer effects. Apoptosis induced by EGCg and subsequent cell growth suppression have been demonstrated in a number of cell culture studies. However, the underlying mechanism of apoptotic cell death remains unclear. Thus, the aim of the present study was to identify the major molecule that mediates proapoptotic cell death by EGCg. The effect of EGCg on cell proliferation and the induction of mRNA that modulates apoptotic cell death was evaluated in the A549 human non-small-cell lung cancer cell line. In addition, morphological changes were assessed by microscopy in A549 cells that had been treated with 100 μM EGCg for 24 h. The MTT assay revealed that cell proliferation was significantly reduced by EGCg in a dose-dependent manner (3–100 μM). The mRNA expression level of B-cell lymphoma-extra large (Bcl-xL) was decreased in A549 cells following 24 h incubation with 100 μM EGCg. Therefore, the results indicated that the inhibition of cell proliferation by EGCg may be achieved via suppressing the expression of the cell death-inhibiting gene, Bcl-xL.

Ouabain protects against Shiga toxin-triggered apoptosis by reversing the imbalance between Bax and Bcl-xL

Hemolytic uremic syndrome, a life-threatening disease often accompanied by acute renal failure, usually occurs after gastrointestinal infection with Shiga toxin 2 (Stx2)-producing Escherichia coli. Stx2 binds to the glycosphingolipid globotriaosylceramide receptor, expressed by renal epithelial cells, and triggers apoptosis by activating the apoptotic factor Bax. Signaling via the ouabain/Na,K-ATPase/IP3R/NF-κB pathway increases expression of Bcl-xL, an inhibitor of Bax, suggesting that ouabain might protect renal cells from Stx2-triggered apoptosis. Here, exposing rat proximal tubular cells to Stx2 in vitro resulted in massive apoptosis, upregulation of the apoptotic factor Bax, increased cleaved caspase-3, and downregulation of the survival factor Bcl-xL; co-incubation with ouabain prevented all of these effects. Ouabain activated the NF-κB antiapoptotic subunit p65, and the inhibition of p65 DNA binding abolished the antiapoptotic effect of ouabain in Stx2-exposed tubular cells. Furthermore, in vivo, administration of ouabain reversed the imbalance between Bax and Bcl-xL in Stx2-treated mice. Taken together, these results suggest that ouabain can protect the kidney from the apoptotic effects of Stx2.

Glutamine modulates CD8αα(+) TCRαβ(+) intestinal intraepithelial lymphocyte expression in mice with polymicrobial sepsis

OBJECTIVES

CD8αα(+) T-cell receptor (TCR) αβ(+) intestinal intraepithelial lymphocytes (IELs) were found to have a regulatory function in the mucosal immune system. Glutamine (GLN) is an amino acid with immunomodulatory effects. The aim of this study was to investigate the influences of GLN on the proportion of CD8αα(+) TCRαβ(+) IELs and associated inflammatory mediator gene expression in polymicrobial sepsis.

METHODS

Mice were randomly assigned to a normal (NC) group, a sepsis with saline (SS) group, or a sepsis with GLN (SG) group. The NC group was fed a chow diet. Sepsis was induced by cecal ligation and puncture (CLP). The SS group was administered saline, and the SG group was given 0.75 g GLN/kg body weight via a tail vein after CLP. Mice were sacrificed 12 h after CLP, and CD8αα(+) TCRαβ(+) IELs were isolated for further analysis.

RESULTS

Sepsis resulted in a lower percentage of CD8αα(+) TCRαβ(+) IELs, and higher messenger (m)RNA expression of complement 5a receptor, interleukin (IL)-2 receptor β, IL-15 receptor α, and interferon-γ by CD8αα(+) TCRαβ(+) IELs. These immunomodulatory mediator genes decreased, whereas IL-7 receptor and transforming growth factor-β expressions increased in CD8αα(+) TCRαβ(+) IELs in septic mice with GLN administration. Annexin V⁄7-AAD staining revealed significantly lower apoptotic rates of CD8αα(+) TCRαβ(+) IELs in the SG group.

CONCLUSION

A single dose of GLN administered after the initiation of sepsis increased the percentage of CD8αα(+) TCRαβ(+) IELs, prevented apoptosis of CD8αα(+) TCRαβ(+) IELs, and downregulated CD8αα(+) TCRαβ(+) IEL-expressed inflammatory mediators. These results suggest that GLN influenced the distribution and cytokine secretion of the CD8αα(+) TCRαβ(+) IEL subset, which may ameliorate sepsis-induced inflammatory reactions and thus mitigate the severity of intestinal epithelial injury.

Enhanced function of cytotoxic T lymphocytes induced by dendritic cells modified with truncated PSMA and 4-1BBL

Interactions between costimulatory molecules and their receptors are vital for Ag-presenting dendritic cells (DCs) to initiate T cells activation, expansion and their antitumor immune responses. Augmentation of costimulatory signal due to the interaction of DCs and T cells may amplify, sustain and drive diversity of cytotoxic T lymphocytes (CTLs) and consequently enhance the antitumor response. 4-1BBL/4-1BB is such a pair of costimulatory ligand and receptor, playing an important role in the co-stimulation of CTLs. Previously, we demonstrated that DCs transduced with recombinant adenovirus encoding truncated PSMA (tPSMA) and m4-1BBL could induce prostate cancer regression in mouse models. In the present study, we further explored the adjuvant role of 4-1BBL in modulating CTLs activation induced by tPSMA gene-pulsed DCs. The apoptosis and cytotoxicity against tPSMA expressing RM-1 cells of CTLs were determined. Results showed that tPSMA gene-pulsed DCs effectively induced T lymphocyte activation and cytotoxicity, which was enhanced by upregulated expression of 4-1BBL, displaying better cell viability, lower CTLs apoptosis, higher expression anti-apoptotic protein of Bcl-xL and phosphorylation of P38, enhanced NF-κB activation, as well as more IFN-γ production. These results demonstrated that 4-1BBL may play a significant role in the co-stimulation pathway for Ag-presenting DCs-mediated CTLs activity, which might be a beneficial adjuvant factor for DCs-based cancer immunotherapy.

Dapper homolog 1 is a novel tumor suppressor in gastric cancer through inhibiting the nuclear factor-κB signaling pathway

Dapper homolog 1 (DACT1) is a disheveled partner in the planar cell polarity pathway. By using genome-wide promoter methylation screening, dapper homolog 1 (DACT1) was found to be frequently methylated in gastric cancer. We aim to clarify its epigenetic inactivation, biological function and clinical implication in gastric cancer. We demonstrated that DACT1 was silenced in 7 of 10 gastric cancer cell lines and in primary gastric cancers. Transcriptional gene silence of DACT1 was mainly regulated by promoter hypermethylation. Ectopic expression of DACT1 in silenced gastric cancer cell lines (AGS, BGC823 and MGC803) by stable transfection suppressed colony formation (P < 0.001), induced cell apoptosis (P < 0.01) and retarded tumorigenesis in nude mice (P < 0.001). The tumor suppressive effect of DACT1 was further confirmed by loss of DACT1 function experiment. The proapoptotic and antiproliferative effect by DACT1 was associated with inhibition of nuclear factor (NF)-κB activation and its downstream factors, including B-cell CLL/lymphoma-2, Bcl-X, interleukin-8 and tumor necrosis factor-α. Moreover, promoter methylation of DACT1 was detected in 29.3% (60/205) of primary gastric tumors. DACT1 methylation was significantly associated with tumor metastasis (P < 0.05), invasion (P < 0.05) and advanced tumor stage (P < 0.0005). These findings provided insight into the role of DACT1 as a novel functional tumor suppressor in gastric cancer through inhibiting NF-κB signaling pathway. Promoter methylation of DACT1 is associated with tumor aggressiveness.

RCAN1 is an important mediator of glucocorticoid-induced apoptosis in human leukemic cells

Glucocorticoid (GC) is a major therapeutic agent for the treatment of leukemia because of its ability to induce apoptosis in lymphoid cells. The mechanism causing apoptosis, however, is still controversial. Since the glucocorticoid receptor is a transcription factor, some of its target genes are expected to be implicated in apoptosis. In this study, using a GC-sensitive human pre-B leukemia cell line, Nalm-6, the FK506 binding protein 51 (FKBP5) and regulator of calcineurin 1 (RCAN1) genes were disrupted by homologous recombination, since the expression of both is up-regulated by GC in GC-sensitive but not in GC-resistant leukemic cell lines. While the disruption of FKBP5 had a marginal effect on GC-induced apoptosis, that of RCAN1 resulted in marked resistance to GC. In addition, overexpression of RCAN1 rendered cells more sensitive to DEX. In RCAN1-disrupted cells, levels of some pro-apoptotic and anti-apoptotic Bcl-2 family proteins were decreased and increased, respectively. Finally, phosphorylation of cAMP-response element binding protein (CREB) and up-regulation of CREB target genes by GC were inhibited by RCAN1 disruption, and treatment with a cAMP-inducing agent, forskolin, restored the sensitivity to GC in RCAN1-disrupted Nalm-6 cells. These findings suggest that up-regulation of RCAN1 expression followed by activation of the CREB pathway is required in GC-induced apoptosis.

T cell receptor/CARMA1/NF-κB signaling controls T-helper (Th) 17 differentiation

IL-17-producing CD4 T cells play a key role in immune responses against extracellular bacteria and autoimmunity. Nuclear factor κB (NF-κB) is required for T-cell activation and selected effector functions, but its role in Th17 differentiation is controversial. Using genetic mouse models that impede T-cell-NF-κB signaling either downstream of the T-cell receptor (TCR) or of IκB kinase β (IKKβ), we demonstrate that NF-κB signaling controls not only survival and proliferation of activated T cells, but, if cell survival and cell-cycle progression are enabled, has an additional role in promoting completion of Th17 differentiation. CARD-containing MAGUK protein 1 (CARMA1), an adapter required for TCR/NF-κB signaling, was necessary for acquisition of IL-17A, IL-17F, IL-21, IL-22, IL-23R, and CCR6 expression in T cells cultured under Th17 conditions. In proliferating cells, lack of CARMA1 selectively prevented Th17, but not Th1 or Th2 differentiation, in a cell-intrinsic manner. Consistent with these data, CARMA1-KO mice were resistant to experimental autoimmune encephalomyelitis. Surprisingly, transcription factors essential for Th17 differentiation such as RORγt, AHR, and IRF4 were normally induced in CARMA1-KO T cells activated under Th17 conditions, suggesting that the Th17 differentiation program was initiated normally. Instead, chromatin loci of Th17 effector molecules failed to acquire an open conformation in CARMA1-KO T cells. Our results demonstrate that TCR/CARMA1/NF-κB controls completion of Th17 differentiation by enabling chromatin accessibility of Th17 effector molecule loci.

Sublytic complement protects prostate cancer cells from tumour necrosis factor-α-induced cell death

Inflammation is a critical component of tumour progression. Although complement and tumour necrosis factor (TNF)-α potentially exert significant anti-tumour effects, both mediators may also promote tumour progression. It has been demonstrated that sublytic complement confers resistance on tumour cells not only against lytic complement, but also other danger molecules such as perforin. In low concentrations, TNF promotes survival of malignant cells rather than exerting cytotoxic activity. In this study, we tested if sublytic complement is able to interfere with TNF-mediated tumour cell killing. Our results demonstrate that either subcytotoxic concentrations of TNF or sublytic complement rescue prostate carcinoma cells (DU145) from TNF-α-mediated cell death. Upon pretreatment with low-dose TNF-α, but not upon pre-exposure to sublytic complement, TNF resistance was associated with the down-regulation of TNF receptor 1 (TNF-R1) expression. Complement-induced protection against TNF-mediated apoptosis accompanied the induction of anti-apoptotic proteins [B cell leukaemia/lymphoma (Bcl)-2 and Bcl-xL] at an early stage followed by inhibition of the TNF-induced decrease in the amount of Bcl-2 and Bcl-xL. Cell protection also accompanied the inhibition of caspase-8 activation, poly (ADP-ribose) polymerase (PARP)-1 cleavage and the activation of nuclear factor (NF)-κB. Our data extend our current view on the induction of tumour cell resistance against cytotoxic mediators supporting the role of the tumour microenvironment in mediating protection against the anti-cancer immune response.

CD28 promotes CD4+ T cell clonal expansion during infection independently of its YMNM and PYAP motifs

CD28 is required for maximal proliferation of CD4+ T cells stimulated through their TCRs. Two sites within the cytoplasmic tail of CD28, a YMNM sequence that recruits PI3K and activates NF-κB and a PYAP sequence that recruits Lck, are candidates as transducers of the signals responsible for these biological effects. We tested this proposition by tracking polyclonal peptide:MHCII-specific CD4+ T cells in vivo in mice with mutations in these sites. Mice lacking CD28 or its cytoplasmic tail had the same number of naive T cells specific for a peptide:MHCII ligand as wild-type mice. However, the mutant cells produced one tenth as many effector and memory cells as wild-type T cells after infection with bacteria expressing the antigenic peptide. Remarkably, T cells with a mutated PI3K binding site, a mutated PYAP site, or both mutations proliferated to the same extent as wild-type T cells. The only observed defect was that T cells with a mutated PYAP or Y170F site proliferated even more weakly in response to peptide without adjuvant than wild-type T cells. These results show that CD28 enhances T cell proliferation during bacterial infection by signals emanating from undiscovered sites in the cytoplasmic tail.

Effects of alanyl-glutamine dipeptide on the expression of colon-inflammatory mediators during the recovery phase of colitis induced by dextran sulfate sodium

PURPOSE

Glutamine (Gln) is a nutrient with immunomodulatory effects in metabolic stressed conditions. This study investigated the effects of Gln on colonic-inflammatory-mediator expression and mucosal repair in mice with dextran sulfate sodium (DSS)-induced colitis.

METHODS

C57BL/6 mice received distilled water containing 3 % DSS for 5 d to induce colitis. One of the DSS-treated groups was intraperitoneally injected with an alanyl (Ala)-Gln solution 3 days before (G-DSS) while the other group was administered Ala-Gln 3 days after colitis (DSS-G) was induced. The Ala-Gln solution provided 0.5 g Gln/kg/d. The saline-DSS group (S-DSS) received an identical amount of saline before and after colitis was induced to serve as a positive control.

RESULTS

The S-DSS group had a shorter colon length, higher plasma haptoglobin level, and more-severe colon inflammation. Also, the toll-like receptor (TLR)4 level, nuclear factor (NF)-κB activation, and inflammatory cytokine gene expression in the colon were higher than those of the normal control group. Gln administration either before or after colitis suppressed TLR4 protein levels, decreased plasma haptoglobin, and reduced colon inflammation. Histological inflammatory scores were also lowered. Compared to the post-colitis Gln group, preventive use of Gln had higher colon length, expressions of mucin 2, trefoil factor 3, and heat shock protein 72 genes were also upregulated in the colon.

CONCLUSIONS

These results suggest that Gln administered either before or after the colitis mitigated inflammation of colitis that was not observed in group without Gln injection. Prophylactic treatment with Gln had more-beneficial effects on reducing inflammatory markers and enhancing the recovery of mucosa in DSS-induced colitis.

Wip1 sensitizes p53-negative tumors to apoptosis by regulating the Bax/Bcl-xL ratio

Wip1 is a stress-response phosphatase that negatively regulates several tumor suppressors, including p53. In a sizeable fraction of tumors, overexpression or amplification of Wip1 compromises p53 functions; inhibition of Wip1 activity is an attractive strategy for improving treatment of these tumors. However, over half of human tumors contain mutations in the p53 gene or have lost both alleles. Recently, we observed that in cancer cells lacking wild type p53, reduction of Wip1 expression was ineffective, whereas, surprisingly, overexpression of Wip1 increased anticancer drug sensitivity. The increased sensitivity resulted from activation of the intrinsic pathway of apoptosis through increased levels of the pro-apoptotic protein Bax and decreased levels of the anti-apoptotic protein Bcl-xL. We showed that interaction of Wip1 and the transcription factor RUNX2, specifically through dephosphorylation of RUNX2 phospho-S432, resulted in increased expression of Bax. Interestingly, overexpression of Wip1 increased drug sensitivity only in the p53-negative tumor cells while protecting the wild type p53-containing normal cells from drug-induced collateral injury. Here, we provide evidence that Wip1 overexpression decreases expression of Bcl-xL through negative regulation of NFκB activity. Thus, Wip1 overexpression increases the sensitivity of p53-negative cancer cells to anticancer drugs by separately affecting Bax and Bcl-xL protein levels.

Treatment of acute lymphoblastic leukemia with an rGel/BLyS fusion toxin

Acute lymphoblastic leukemia (ALL) is the most common malignancy affecting children and a major cause of mortality from hematopoietic malignancies in adults. A substantial number of patients become drug resistant during chemotherapy, necessitating the development of alternative modes of treatment. rGel (recombinant Gelonin)/BlyS (B-lymphocyte stimulator) is a toxin-cytokine fusion protein used for selective killing of malignant B-cells expressing receptors for B-cell-activating factor (BAFF/BLyS) by receptor-targeted delivery of the toxin, Gelonin. Here, we demonstrate that rGel/BLyS binds to ALL cells expressing BAFF receptor (BAFF-R) and upon internalization, it induces apoptosis of these cells and causes downregulation of survival genes even in the presence of stromal protection. Using an immunodeficient transplant model for human ALL, we show that rGel/BLyS prolongs survival of both Philadelphia chromosome-positive and negative ALL-bearing mice. Furthermore, we used AMD3100, a CXCR4 antagonist, to mobilize the leukemic cells protected in the bone marrow (BM) microenvironment and the combination with rGel/BLyS resulted in a significant reduction of the tumor load in the BM and complete eradication of ALL cells from the circulation. Thus, a combination treatment with the B-cell-specific fusion toxin rGel/BLyS and the mobilizing agent AMD3100 could be an effective alternative approach to chemotherapy for the treatment of primary and relapsed ALL.