Molecular regulation of human interleukin 2 and T-cell function by interleukin 4

Using single cell atlas data to reconstruct regulatory networks

Inference of global gene regulatory networks from omics data is a long-term goal of systems biology. Most methods developed for inferring transcription factor (TF)-gene interactions either relied on a small dataset or used snapshot data which is not suitable for inferring a process that is inherently temporal. Here, we developed a new computational method that combines neural networks and multi-task learning to predict RNA velocity rather than gene expression values. This allows our method to overcome many of the problems faced by prior methods leading to more accurate and more comprehensive set of identified regulatory interactions. Application of our method to atlas scale single cell data from 6 HuBMAP tissues led to several validated and novel predictions and greatly improved on prior methods proposed for this task.

Antimetabolite pemetrexed primes a favorable tumor microenvironment for immune checkpoint blockade therapy

Background

The immune checkpoint blockade (ICB) targeting programmed cell death-1 (PD-1) and its ligand (PD-L1) has been proved beneficial for numerous types of cancers, including non-small-cell lung cancer (NSCLC). However, a significant number of patients with NSCLC still fail to respond to ICB due to unfavorable tumor microenvironment. To improve the efficacy, the immune-chemotherapy combination with pemetrexed, cis/carboplatin and pembrolizumab (anti-PD-1) has been recently approved as first-line treatment in advanced NSCLCs. While chemotherapeutic agents exert beneficial effects, the underlying antitumor mechanism(s) remains unclear.

Methods

Pemetrexed, cisplatin and other chemotherapeutic agents were tested for the potential to induce PD-L1 expression in NSCLC cells by immunoblotting and flow cytometry. The ability to prime the tumor immune microenvironment was then determined by NSCLC/T cell coculture systems and syngeneic mouse models. Subpopulations of NSCLC cells responding differently to pemetrexed were selected and subjected to RNA-sequencing analysis. The key signaling pathways were identified and validated in vitro and in vivo.

Results

Pemetrexed induced the transcriptional activation of PD-L1 (encoded by CD274) by inactivating thymidylate synthase (TS) in NSCLC cells and, in turn, activating T-lymphocytes when combined with the anti-PD-1/PD-L1 therapy. Nuclear factor κB (NF-κB) signaling was activated by intracellular reactive oxygen species (ROSs) that were elevated by pemetrexed-mediated TS inactivation. The TS−ROS−NF-κB regulatory axis actively involves in pemetrexed-induced PD-L1 upregulation, whereas when pemetrexed fails to induce PD-L1 expression in NSCLC cells, NF-κB signaling is unregulated. In syngeneic mouse models, the combinatory treatment of pemetrexed with anti-PD-L1 antibody created a more favorable tumor microenvironment for the inhibition of tumor growth.

Conclusions

Our findings reveal novel mechanisms showing that pemetrexed upregulates PD-L1 expression and primes a favorable microenvironment for ICB, which provides a mechanistic basis for the combinatory chemoimmunotherapy in NSCLC treatment.

Select agent program impact on the IBC

Stringent, exacting and local oversight for the control and use of Select Agents and Toxins is crucial to ensuring biosecurity. However, review of research involving Select Agents and Toxins can present particular challenges to the Institutional Biosafety Committee (IBC). Institutional review for biosecurity programs focuses on security assessments and access control, whereas most IBCs primarily focus on occupational exposure assessment, biohazard control, and biosafety practices. Determining how and where to interweave biosecurity program requirements into programs based on occupational health priorities is the key to integrated and effective compliance management. Recent new or pending regulations on dual use or gain of function research suggests or mandates additional duties for the IBC. This chapter explores challenges and strategies for institutional oversight and support of Select Agent program compliance.

Merging drops in a Teflon tube, and transferring fluid between them, illustrated by protein crystallization and drug screening

The ability to manipulate drops with small volumes has many practical applications. Current microfluidic devices generally exploit channel geometry and/or active external equipment to control drops. Here we use a Teflon tube attached to a syringe pump and exploit the properties of interfaces between three immiscible liquids to create particular fluidic architectures. We then go on to merge any number of drops (with volumes of micro- to nano-liters) at predefined points in time and space in the tube; for example, 51 drops were merged in a defined order to yield one large drop. Using a different architecture, specified amounts of fluid were transferred between 2 nl drops at specified rates; for example, 2.5 pl aliquots were transferred (at rates of ~500 fl s(-1)) between two drops through inter-connecting nano-channels (width ~40 nm). One proof-of-principle experiment involved screening conditions required to crystallize a protein (using a concentration gradient created using such nano-channels). Another demonstrated biocompatibility; drugs were mixed with human cells grown in suspension or on surfaces, and the treated cells responded like those grown conventionally. Although most experiments were performed manually, moderate high-throughput potential was demonstrated by mixing ~1000 different pairs of 50 nl drops in ~15 min using a robot. We suggest this reusable, low-cost, and versatile methodology could facilitate the introduction of microfluidics into workflows of many experimental laboratories.

Blimp-1 induced by IL-4 plays a critical role in suppressing IL-2 production in activated CD4 T cells

Although an inhibitory function of IL-4 in CD4 T cell IL-2 production has long been recognized, a mechanism mediating the inhibition remains unclear. In this study we demonstrate that IL-4 displays a potent suppressive function in IL-2 production of activated CD4 T cells through STAT6. IL-4-induced IL-2 suppression required IL-2 because IL-2 neutralization restored the production of IL-2 even in the presence of IL-4. In vivo, enhanced IL-2 production was found in nematode-infected IL-4- or STAT6-deficient animals, whereas immunization in the presence of IL-4 substantially diminished IL-2 production by Ag-specific CD4 T cells. IL-2 mRNA expression was reduced when T cells were stimulated in the presence of IL-4, whereas IL-2 mRNA decay was unaltered, suggesting that IL-4 mediates the suppression at a transcriptional level. Blimp-1 induced by IL-4 stimulation in activated CD4 T cells was found to be necessary to mediate the IL-2 inhibition as IL-4-mediated IL-2 suppression was less pronounced in activated CD4 T cells deficient in Blimp-1. Taken together, our results demonstrate a potential link with IL-4, Blimp-1, and IL-2 production, suggesting that Blimp-1 may play an important role in controlling IL-2 production in activated T cells and in adaptive T cell immunity.

Are immunological mechanisms involved in colon cancer and are they possible markers for biotherapy improvement?

This paper focuses on our data on colon cancer patients. Our overall results lead us to believe that the suppressive effect of specific cytokines in colon cancer patients alters the functionality of TH1 and TH2 subsets of CD4+ T-cells, with an expansion of TH2 cells and a malfunctioning of TH1 cells. This immunological disregulation appears to increase with stage progression, suggesting a direct role in the mechanisms that allow the tumour to locate and expand within the host. It is also clear that in order to identify disease markers and generate an in vivo immune response that corrects the imbalance between TH1 and TH2 cells, we need to understand how tumour mechanisms cause this imbalance to begin with.

Colon cancer and gene alterations: their immunological implications and suggestions for prognostic indices and improvements in biotherapy

Studies have shown that changes occur in c-Ki-ras, p53, and Bcl2 gene structure and function during the various stages of human colon carcinogenesis. Alterations of these genes are responsible for the establishment of a state of continuous stimulus for cell division and apoptotic inhibition at physiological and pharmacological levels. This paper focuses on the results of our research aimed at investigating how these gene alterations influence tumoral mechanisms on an immunological level and how immunological parameters can be used as prognostic markers for the passage of normal tissue to adenoma and adenoma to carcinoma. Overall, our data suggest that an alteration in the c-Ki-ras gene results in a switch to a suppressive type of immune response, determining an impairment of immune cell activation at both antigen- presenting-cell and T-cell levels. c-Ki-ras gene mutations, p53 deletions, and Bc12 expression, on the other hand, can be used as prognostic markers for the passage of normal tissue to adenoma and adenoma to carcinoma. The p53 oncogene does not appear to impair patients' immunological response further. In conclusion, an evaluation of c-Ki-ras, rather than p53 gene alterations, would seem to be more relevant in colon cancer prevention programs and biotherapy improvement.

The Study of a Patient's Immune System May Prove to be a Useful Noninvasive Tool for Stage Classification in Colon Cancer

Therapy, and, therefore, prognosis, is strictly related to cancer stage, and hence, screening tests that can contribute to the early classification of disease stage represent a step forward in treatment. Unfortunately, few prognostic indices are available, especially noninvasive ones. Our study of the physiological network of the immune response, however, leads us to believe that it may well be possible to define immunological indices for the classification of cancer stage using blood parameters. In this paper, we show how the study of a patient's immune system can be used as a noninvasive tool for early-stage classification.

Retinoic acid stimulates chondrocyte differentiation and enhances bone morphogenetic protein effects through induction of Smad1 and Smad5

Whereas bone morphogenetic protein (BMP)-signaling events induce maturational characteristics in vitro, recent evidence suggests that the effects of other regulators might be mediated through BMP-signaling events. The present study examines the mechanism through which retinoic acid (RA) stimulates differentiation in chicken embryonic caudal sternal chondrocyte cultures. Both RA and BMP-2 induced expression of the chondrocyte maturational marker, colX, in chondrocyte cultures by 8 d. Though the RA effect was small, it synergistically enhanced the effect of BMP-2 on colX and phosphatase activity. Inhibition of either RA or BMP signaling, with selective inhibitors, interfered with the inductive effects of these agents but also inhibited the complementary pathway, demonstrating a codependence of RA and BMP signaling during chondrocyte maturation. BMP-2 did not enhance the effects of RA on an RA-responsive reporter construct, but RA enhanced basal activity and synergistically enhanced BMP-2 stimulation of the BMP-responsive chicken type X collagen reporter. A similar synergistic interaction between RA and BMP-2 was observed on colX expression. RA did not increase the expression of the type IA BMP receptor but did markedly up-regulate the expression of Smad1 and Smad5 proteins, important participants in the BMP pathway. Inhibition of RA signaling, with the selective inhibitor AGN 193109, blocked RA-mediated induction of the Smad proteins and chondrocyte differentiation. These findings demonstrate that RA induces the expression of BMP-signaling molecules and enhances BMP effects in chondrocytes.

Growth plate chondrocyte maturation is regulated by basal intracellular calcium

Among the cellular events that are associated with the process of endochondral ossification is an incremental increase in chondrocyte basal intracellular free Ca(2+) concentration ([Ca(2+)](i)) from 50 to 100 nM. To determine if this rise in [Ca(2+)](i) functionally participates in the maturational process of growth plate chondrocytes (GPCs), we examined its effect on several markers of hypertrophy, including annexin V, bone morphogenetic protein-6, type X collagen, and indian hedgehog. Expression of these genes was determined under conditions either where the Ca(2+) chelator EGTA was used to deplete extracellular Ca(2+) and lower [Ca(2+)](i) to < 50 nM or where the extracellular addition of 5 mM CaCl(2) was used to elevate [Ca(2+)](i) to > 100 nM. Although no effect on the expression of these genes was observed following treatment with 5 mM CaCl(2), 4 mM EGTA significantly inhibited their expression. This effect was recapitulated in sternal chondrocytes and was reversed following withdrawal of EGTA. Based on these findings, we hypothesized that the EGTA-induced suppression of these genes was mediated by a factor whose expression is responsive to changes in basal [Ca(2+)](i). Since EGTA mimicked the effect of parathyroid hormone-related peptide (PTHrP) on GPC maturation, we examined the effect of low [Ca(2+)](i) on PTHrP expression. Suggesting that low [Ca(2+)](i) suppression of hypertrophy was PTHrP-dependent in GPCs, (a) treatment with 4 mM EGTA increased PTHrP expression, (b) the EGTA effect was rescued by blocking PTHrP binding to its receptor with the competitive antagonist TIP(7-39), and (c) EGTA could mimic the PTHrP stimulation of AP-1 binding to DNA. Additionally, PTHrP promoter analysis identified a domain (-1498 to -862, relative to the start codon) involved with conferring Ca(2+) sensitivity to the PTHrP gene. These findings underscore the importance of cellular Ca(2+) in GPC function and suggest that PTHrP action in the growth plate is at least partially regulated by changes in basal [Ca(2+)](i).

Thyroid specific T helper cell analysis by ELISPOT assay with thyrotropin receptor (TSH-R) peptides

We previously reported that a synthetic peptide induced humoral autoimmunity to thyrotropin receptor (TSH-R) and the expansion of antigen-specific type 2 helper T (Th2) cell population in mice. The peptide corresponds to the human TSH-R C-terminal region. In the present study, we undertook a similar approach in patients with Graves' disease (GD). Peripheral lymphocytes from 5 healthy controls and 11 GD patients were prepared and analyzed for cytokines from helper T cells by an antigen specific enzyme-linked immuno spot (ELISPOT) assay. In GD patients, the total number of IL-4 producing cells increased significantly and the number of interferon-gamma(IFN-gamma) producing cells decreased. Further, co-incubation with several of the 20 kinds of TSH-R extracellular peptides increased the number of IL-4 producing cells in patients with GD. Such stimulatory peptides appear frequently in a TSH-R sequence. These peptides did not affect the numbers of IFN-gamma producing cells significantly. These results indicated that GD patients have an expanded Th2 population responding to TSH-R and the dominance of the humoral immune system in such patients.

PTHrP modulates chondrocyte differentiation through AP-1 and CREB signaling

During the process of differentiation, chondrocytes integrate a complex array of signals from local or systemic factors like parathyroid hormone-related peptide (PTHrP), Indian hedgehog, bone morphogenetic proteins and transforming growth factor beta. While PTHrP is known to be a critical regulator of chondrocyte proliferation and differentiation, the signaling pathways through which this factor acts remain to be elucidated. Here we show that both cAMP response element-binding protein (CREB) and AP-1 activation are critical to PTHrP signaling in chondrocytes. PTHrP treatment leads to rapid CREB phosphorylation and activation, while CREB DNA binding activity is constitutive. In contrast, PTHrP induces AP-1 DNA binding activity through induction of c-Fos protein expression. PTHrP activates CRE and TRE reporter constructs primarily through PKA-mediated signaling events. Both signaling pathways were found to be important mediators of PTHrP effects on chondrocyte phenotype. Alone, PTHrP suppresses maturation and stimulates proliferation of the chondrocyte cultures. However, in the presence of dominant negative inhibitors of CREB and c-Fos, these PTHrP effects were suppressed, and chondrocyte maturation was accelerated. Moreover, in combination, the effects of dominant negative c-Fos and CREB are synergistic, suggesting interaction between these signaling pathways during chondrocyte differentiation.

Smad2 and 3 mediate transforming growth factor-beta1-induced inhibition of chondrocyte maturation

Transforming growth factor-beta (TGF-beta) is a multifunctional regulator of a variety of cellular functions, including proliferation, differentiation, matrix synthesis, and apoptosis. In growth plate chondrocytes, TGF-beta slows the rate of maturation. Because the current paradigm of TGF-beta signaling involves Smad proteins as downstream regulators of target genes, we have characterized their role as mediators of TGF-beta effects on chondrocyte maturation. Both Smad2 and 3 translocated to the nucleus upon TGF-beta1 signaling, but not upon BMP-2 signaling. Cotransfection experiments using the TGF-beta responsive and Smad3 sensitive p3TP-Lux luciferase reporter demonstrated that wild-type Smad3 potentiated, whereas dominant negative Smad3 inhibited TGF-beta1 induced luciferase activity. To confirm the role of Smad2 and 3 as essential mediators of TGF-beta1 effects on chondrocyte maturation, we overexpressed both wild-type and dominant negative Smad2 and 3 in virally infected chondrocyte cultures. Overexpression of both wild-type Smad2 and 3 potentiated the inhibitory effect of TGF-beta on chondrocyte maturation, as determined by colx and alkaline phosphatase activity, whereas dominant negative Smad2 and 3 blocked these effects. Wild-type and dominant negative forms of Smad3 had more pronounced effects than Smad2. Our results define Smad2 and 3 as key mediators of the inhibitory effect of TGF-beta1 signaling on chondrocyte maturation.

NF-kappa B regulates VCAM-1 expression on fibroblast-like synoviocytes

Expression of VCAM-1 on synovial fibroblasts is a clinical hallmark of rheumatoid arthritis. The interaction of VCAM-1 and its integrin receptor very late Ag-4 is believed to be critically involved in the recruitment and retention of immune cells in the inflamed joints. To study the regulation of VCAM-1 in synovial fibroblasts, fibroblast-like synoviocytes (FLS) were isolated from the knee joints of normal mice and passaged repeatedly to obtain a homogeneous cell population. We have found that VCAM-1 is constitutively expressed on mouse FLS (mFLS) and that its surface expression is further increased after exposure to TNF-alpha. Nuclear translocation of transcription factor NF-kappa B including P50/P50 homodimer and P65/P50 heterodimer was activated by TNF-alpha treatment. In mFLS stably expressing a dominant-negative mutant of the inhibitory protein I-kappa B alpha- (mI-kappa B), which does not undergo proteolytic degradation, NF-kappa B remains in the cytosol and its activation in response to TNF-alpha is abolished. VCAM-1 protein expression after TNF-alpha stimulation was blocked in cells expressing the mI-kappa B. This effect is likely due to the loss of NF-kappa B-mediated transcription of VCAM-1, because the 5-fold increase in mRNA levels in response to TNF-alpha is absent in the mutant cells. To confirm these findings, we transduced mFLS with an adenoviral vector containing the mI-kappa B transgene. VCAM-1 expression was also blocked by mI-kappa B in this system, whereas cells transduced with a control adenoviral vector remained responsive to TNF-alpha. These results indicate that NF-kappa B mediates TNF-alpha-induced VCAM-1 expression on mFLS.

Molecular regulation of granulocyte macrophage colony-stimulating factor in human lung epithelial cells by interleukin (IL)-1beta, IL-4, and IL-13 involves both transcriptional and post-transcriptional mechanisms

Interleukin (IL)-1beta stimulates the release of granulocyte macrophage colony-stimulating factor (GM-CSF) from lung epithelial cells. To investigate the molecular mechanisms underlying GM-CSF regulation, we studied GM-CSF production, messenger RNA (mRNA) expression levels, and GM-CSF promoter activity in A549 human alveolar carcinoma cells stimulated with IL-1beta. Coincubation with IL-4 or IL-13 dose-dependently inhibited IL-1beta-induced GM-CSF release. Time-course studies of intracellular and extracellular protein release and mRNA expression indicated tight coupling of protein and mRNA synthesis within 6 h after stimulation. IL-4 and IL-13 both inhibited expression of GM-CSF mRNA and protein by 2 h after stimulation. Stable transfection of A549 cells, with GM-CSF promoter/ enhancer constructs containing up to 3.3 kb upstream of the transcription start site, revealed maximal activation by IL-1beta and phorbol 12-myristate 13-acetate (PMA) with a reporter containing the proximal promoter (-627 to +35). This excludes sequences further upstream from a major regulatory role in GM-CSF promoter activation by IL-1beta or PMA in these cells. IL-4 and IL-13 downregulated promoter activation but had no effect on GM-CSF mRNA half-life. However, IL-1beta activation of all constructs was far less pronounced than in Jurkat T cells, suggesting a requirement for additional mechanisms, possibly post-transcriptional, to potentiate the observed transcriptional induction.

Tumor necrosis factor-alpha/nuclear transcription factor-kappaB signaling in periprosthetic osteolysis

Due to irreversible joint destruction caused by the various arthritides, more than 400,000 total joint arthroplasties are performed each year in the United States. As many as 20% of these require revision surgery because of aseptic loosening. The current paradigm to explain aseptic loosening is that wear debris generated from the prosthesis stimulates the release of proinflammatory cytokines (i.e., tumor necrosis factor-alpha and interleukins 1 and 6) following phagocytosis by resident macrophages. These cytokines, in turn, initiate an inflammatory response, with the development of an erosive pannus that stimulates bone resorption by osteoclasts. In support of this model, we have previously shown that human monocytes produce large quantities of tumor necrosis factor-alpha in response to titanium particles in vitro. In the current study, we characterized the role of tumor necrosis factor-alpha/nuclear transcription factor-kappaB signaling in the proinflammatory response to titanium particles in vitro and in vivo. Using the mouse macrophage cell line J774, we showed that these cells produce an amount of tumor necrosis factor-alpha in response to titanium particles similar to that produced by human peripheral blood monocytes. The production of tumor necrosis factor-alpha was preceded by a drop in cellular levels of inhibitory factor-kappaBalpha protein and translocation of p50/p65 nuclear transcription factor-KB to the nucleus 30 minutes after stimulation. Levels of tumor necrosis factor-alpha and inhibitory factor-kappaBalpha mRNA increased 30 minutes after stimulation, consistent with the activation of nuclear transcription factor-kappaB. Interleukin-6 mRNA was first seen 4 hours after the addition of the titanium particles, indicating that the production of this cytokine is secondary to the immediate nuclear transcription factor-kappaB response. To test the relevance of tumor necrosis factor-alpha/nuclear transcription factor-kappaB signaling in response to titanium particles in vivo, we adopted an animal model in which the particles were surgically implanted on the calvaria of mice. The animals displayed a dramatic histological response to the debris, with the formation of fibrous tissue and extensive bone resorption after only 1 week. With use of immunohistochemistry and tartrate-resistant acid phosphatase staining, tumor necrosis factor-alpha and osteoclasts were readily detected at the site of inflammation and bone resorption in the calvaria of the treated mice. By testing mice that genetically over-produce tumor necrosis factor-alpha (hTNFalpha-Tg), those defective in tumor necrosis factor-alpha signaling (TNF-RI-/-), and those that are nuclear transcription factor-kappaB1-deficient (NFkappaB1-/-), we evaluated the importance of tumor necrosis factor-alpha/nuclear transcription factor-kappaB signaling in the biological processes responsible for aseptic loosening. The hTNFalpha-Tg mice had a grossly exaggerated response, the TNF-RI(-/-) mice showed little evidence of inflammation or bone resorption, and the nuclear transcription factor-kappaB1(-/-) mice had an inflammatory response without bone resorption. On the basis of these results, we propose a model for periprosthetic osteolysis in which wear debris particles are phagocytosed by macrophages, resulting in the activation of nuclear transcription factor-kappaB and the production of tumor necrosis factor-alpha. Tumor necrosis factor-alpha directly induces fibroblast proliferation and tissue fibrosis and recruits or activates, or both, osteoclasts to resorb adjacent bone.

Analysis of orbital T cells in thyroid-associated ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) has a major effect on the two compartments of the retro-orbital (RO) space, leading to enlargement of the extraocular muscles and other RO tissues. T lymphocyte infiltration of RO tissue is a characteristic feature of TAO and there is current interest in whether these T cells are specifically and selectively reactive to RO tissue itself. We recently established 18 T cell lines (TCL) from RO adipose/connective tissue of six patients with severe TAO by using IL-2, anti-CD3 antibodies and irradiated autologous peripheral blood mononuclear cells (PBMC) to maintain the growth of T cells reactive to autologous RO tissue protein fractions. Here we report on the phenotype characteristics and cytokine gene expression profiles of these orbital TCL and on their immunoreactivity to the organ-specific thyroid antigens thyrotropin receptor (TSH-R), thyroidal peroxidase (TPO) and thyroglobulin (TG). Flow cytometry revealed that 10 TCL were predominantly of CD4+ phenotype, three being mostly CD8+ and five neither CD4+ nor CD8+. Analysis with reverse transcriptase-polymerase chain reaction (RT-PCR) of cytokine gene expression revealed both Th1- and Th2-like products in all TCL: IL-2 product (in 17 TCL), interferon-gamma (IFN-gamma) (n = 10), tumour necrosis factor-beta (TNF-beta) (n = 15), IL-4 (n = 12), IL-5 (n = 17), IL-6 (n = 13), TNF-alpha (n = 12) and IL-10 (n = 4). Reactivity to thyroid antigens was observed only in two TCL, the other 16 being uniformly unreactive. Although 10 out of 18 RO tissue-reactive TCL were predominantly CD4+ there were no significant relationships between TCL phenotype, cytokine gene profile, magnitude of reactivity to RO tissue protein or the (rare) occurrence of thyroid reactivity. The findings of both Th1- and Th2-like cytokine gene expression in all RO tissue-reactive TCL support the concept that TAO is a tissue-specific autoimmune disease, distinct immunologically from the thyroid, and involving both T cell and B cell autoimmune mechanisms in disease pathogenesis.

Copper deficiency reduces interleukin-2 (IL-2) production and IL-2 mRNA in human T-lymphocytes

Although dietary copper (Cu) deficiency has been associated with decreased production of interleukin-2 (IL-2) by activated splenic mononuclear cells in rodent models, the basis for this relationship and its relevance for humans remain unknown. To address these matters, we have developed an in vitro model of cellular copper deficiency by treating Jurkat, a human T-lymphocyte cell line, with low concentrations of 2,3,2-tetraamine (2,3,2-tet), a high affinity copper chelator. Exposure to 5-20 micromol/L 2,3,2-tet for 35 h decreased cell copper and the activity of Cu,Zn-superoxide dismutase (Cu,Zn-SOD) by 30-40% and IL-2 production by 60-70% in cultures activated with phytohemagglutinin and phorbol myristate acetate. Similarly, IL-2 mRNA levels were 40-70% lower in chelator-treated cells than in untreated cells at 3-12 h after activation. In contrast, chelator treatment had no significant effect on cell viability, growth, protein synthesis or mitochondrial activity. The presence of a slight molar excess of copper, but not zinc or iron, during exposure to 2,3,2-tet prevented the chelator-induced decrease in Cu,Zn-SOD activity and the reductions in IL-2 mRNA and bioactivity. Moreover, binding of diferric transferrin (Tf) and cellular uptake of Tf-59Fe by Jurkat cells were not increased by 2,3,2-tet, indicating that chelator-treated cells were not iron deficient. Finally, incubation of human peripheral blood mononuclear cells (PBMC) with 2,3,2-tet decreased mitogen-induced IL-2 production by 50% compared with untreated controls. These data indicate that a decline in copper status decreases IL-2 production by activated human T-cells due to reduced synthesis and/or stability of IL-2 mRNA.

Immunological defects in mice with a targeted disruption in Bcl-3

The proto-oncogene bcl-3 is a member of the IkappaB family. The Bcl-3 protein is known to interact specifically with the p50 and p52 subunits of NFkappaB. However, the function of this interaction is not well understood. To determine the in vivo role of Bcl-3, mice were generated that lack the bcl-3 gene, Bcl 3(-/-). Here we report that Bcl 3(-/-) mice appear developmentally normal, but exhibit severe defects in humoral immune responses and protection from in vivo pathogenic challenges. Relative to wild-type mice, Bcl 3(-/-) mice are unable to clear L. monocytogenes and are more susceptible to infection with S. pneumoniae. This phenotype is similar to that observed in the p50(-/-) mice and the cross between the Bcl-3(-/-) and p50(-/-) mice generates animals with an enhanced phenotype. In accordance with the observed defects in their immune response, the Bcl 3(-/-) mice have normal immunoglobulin levels before and after immunization, but fail to produce antigen-specific antibodies. Additionally, spleens from Bcl-3(-/-) mice are abnormal and void of germinal centers. In contrast, the p50(-/-) mice have normal germinal centers. We propose that in in vivo, Bcl-3 can function independently of p50.

Necessity of biotherapeutic treatments inducing TH1 cell functions in colorectal cancer

Our previous data on colorectal cancer suggest that there are faults at the level of mechanisms of the proliferative responses of patients peripheral blood mononuclear cells (PBMC) to the interleukin (IL)-2 and IL-2 PBMC production, which increase with the stage advancement. The damages in the proliferative response seem to be eliminated by the costimulator effects of the signals produced by the anti-CD3 monoclonal antibody (antiCD3), and the disregulation in TH subsets of CD4+ T cells with a malfunction of TH1 cells and an expansion of TH2, might contribute to this situation. So, by using biotherapeutic treatments to allow the generation of productive immune response in these patients it is essential to identify the defect in their immune system to discover how these mechanisms should be appropriately manipulated in vivo to switch their immune response from a non-productive to a productive one. We have studied this in a group of patients and healthy subjects as the control group, performing their immunological evaluation by determining these parameters: serum levels of IL-2, interferon (IFN) gamma, IL-4, IL-6, IL-7, IL-8, tumour necrosis factor (TNF) alpha, soluble IL-2 receptor (sIL-2R), intercellular adhesion molecule 1 (sICAM-1) and CD30 (sCD30) molecules; PBMC phenotypic antigens expression (CD3, CD4, CD8, CD19, CD16, CD56, CD57, CD25) on peripheral blood mononuclear cells (PBMC); proliferative response of PBMC to IL-2, IL-4 and anti-CD3 monoclonal antibody (antiCD3). Moreover, since mutant c-Ki-ras oncogene is a very frequent finding in colorectal cancers and there are indications which suggest its involvement in tumour progression, the analysis of c-ki-ras codon 12 and 13 were determined and the statistical evaluation of the above immunological parameters were performed by comparing the patient groups with (M+) and without (M-) these mutations with each other, and with the healthy group. The results underline the necessity of biotherapeutic treatments inducing TH1 cell functions in these patients. Moreover in M+ it seems also important to solve the problem of the switch from B to macrophage cells as immune cells which present antigens, and the possible involvement of c-Ki-ras gene mutations in the impairment of T cell receptor activation (TCR).

Interleukin-4 mediates down regulation of antiviral cytokine expression and cytotoxic T-lymphocyte responses and exacerbates vaccinia virus infection in vivo

Interleukin-4 (IL-4) promotes the growth of Th2-type cells while down regulating the development of Th1-type cells. It has been suggested that the actions of this factor inhibit Th1-type effector activity in vivo and may underlie the development of diseases normally controlled by cell-mediated immune responses. Here, we show that clearance of recombinant vaccinia viruses (VV) engineered to express the gene for murine IL-4 is markedly delayed in mice compared with control recombinant VV. While antiviral antibody levels and NK activity in mice given control virus or IL-4-expressing virus were similar, antiviral cytotoxic T-lymphocyte responses were profoundly suppressed throughout the course of infection with the latter. Limiting dilution analysis of IL-4-virus-infected spleens revealed a marked reduction in numbers of cytotoxic T-lymphocyte precursors. Furthermore, reverse transcriptase PCR analysis of splenic mRNA prepared from mice infected with the IL-4-expressing VV showed a marked down regulation of IL-12, gamma interferon, and IL-2 gene expression compared with that from mice given control virus. IL-4 also inhibited the production of nitric oxide (NO), a potent mediator of antimicrobial activity. Together, these data show that IL-4 markedly suppresses the development of antiviral cell-mediated immune responses in vivo with deleterious effects on virus clearance.

Altered Th1/Th2 cytokine profiles in the intestinal mucosa of patients with inflammatory bowel disease as assessed by quantitative reversed transcribed polymerase chain reaction (RT-PCR)

Cytokines serve a central function as key factors in the regulation of the intestinal immune response and mediation of tissue damage in inflammatory bowel disease (IBD). Abnormalities in the expression of immunoregulatory cytokines such as IL-2, IL-4, IL-10 and interferon-gamma (IFN-gamma) may indicate a dysregulation of intestinal immunity probably associated with pathogenic events. Therefore, cytokine mRNA concentrations were determined in the mucosa of patients with IBD at sites of active (n = 13) and inactive (n = 12) ulcerative colitis (UC), active (n = 11) and inactive (n = 11) Crohn's disease (CD) and in control patients (n = 14) using quantitative RT-PCR. IL-10 mRNA concentrations were significantly increased in patients with both active UC (P < 0.001) and active CD (P < 0.005) compared with control patients. IFN-gamma mRNA concentrations were also significantly increased both in patients with active UC (P < 0.02) and active CD (P < 0.05) compared with control patients, whereas IL-2 mRNA levels were significantly (P < 0.02) increased only in active CD. IL-4 mRNA expression in the intestinal mucosa was frequently below the detection limit. Our results demonstrate that chronic intestinal inflammation in patients with CD is characterized by an increase of Th1-like cytokines. Furthermore, the increased IL-10 mRNA expression at sites of active IBD suggests that IL-10 is an important regulatory component involved in the control of the inflammatory response in inflammatory bowel disease.

Regulation of vascular cell adhesion molecule-1 expression by IL-4 and TNF-alpha in cultured endothelial cells

Interaction between vascular cell adhesion molecule-1 (VCAM-1) on endothelial cells and alpha 4 integrins on leukocytes is thought to mediate the selective recruitment of eosinophils and lymphocytes that occurs in allergic diseases. IL-4 is associated with allergic conditions, and it has been shown to selectively increase expression of VCAM-1 on endothelial cells in vivo, suggesting that it could be responsible for VCAM-1 expression in allergic disease. Using a combination of immunofluorescence, flow cytometry, and Northern analysis, we compared the effect of TNF-alpha and IL-4 on VCAM-1 expression. TNF-alpha is also associated with allergic diseases, and it rapidly increases transcription of the VCAM-1 gene. The effect of IL-4 was relatively modest with prolonged kinetics: VCAM-1 was not detected until 72 h after treatment with IL-4. However, when TNF-alpha and IL-4 were combined, there was a synergistic increase in VCAM-1 expression and a dramatic prolongation of the appearance of VCAM-1 on the cell surface. This synergy results from a combination of transcriptional activation by TNF-alpha and the stabilization of resulting transcripts by IL-4. We propose that IL-4 allows subthreshold concentrations of TNF-alpha (concentrations that would not normally activate expression of adhesion molecules on the endothelium) to selectively increase VCAM-1 expression and to prolong its appearance on the surface of cells in allergic disease.

A labile transcriptional repressor modulates endotoxin tolerance

Tolerance to bacterial lipopolysaccharide (LPS, endotoxin) is an adaptive cellular process whereby exposure to endotoxin induces a subsequent hyporesponsive state characterized by decreased levels of LPS-induced cytokine mRNA and protein. We demonstrate, in a human promonocytic cell line, THP-1, that endotoxin tolerance is manifested by decreased LPS-induced interleukin 1 beta (IL-1 beta) transcription. Inhibition of protein synthesis reverses the tolerant phenotype by inducing transcription of IL-1 beta in the absence of a second stimulus. These results indicate that a labile protein contributes to the endotoxin-tolerant phenotype, and that this factor acts in a dominant repressive manner to inhibit the activity of existing transcription factors. We provide further data that cellular expression of I kappa B-alpha correlates with downregulated IL-1 beta gene expression during endotoxin tolerance, implicating I kappa B-alpha as a potential candidate for the labile repressor identified herein.

Interleukin 13 elicits a subset of the activities of its close relative interleukin 4

Interleukin 13 (IL-13) and interleukin 4 (IL-4) are two closely related proteins produced by activated T cells. IL-4 is a well characterized mediator of various aspects of the immune response, including anti-inflammatory effects on monocytes and macrophages, regulation of B cell function, T cell growth, and regulation of adhesion molecule expression on endothelial cells. IL-13, a more recently characterized cytokine, appears to exhibit IL-4-like activities on monocytes, macrophages and human B cells, but has no effect on T cells. While there is a close parallel between IL-4 activities on human and mouse cells, IL-13 activities in these two systems appear to differ substantially with a notable absence of effect on mouse B cells. This review briefly summarizes the current state of knowledge of the interrelated activities of IL-13 and IL-4, explores the basis of these effects at the receptor level and attempts to rationalize the existence of these close relatives via differences in their production by T cells.