Expression of the genes of interferons and other cytokines in normal and diseased tissues of man

Temporal and gefitinib-sensitive regulation of cardiac cytokine expression via chronic β-adrenergic receptor stimulation

Chronic stimulation of β-adrenergic receptors (βAR) can promote survival signaling via transactivation of epidermal growth factor receptor (EGFR) but ultimately alters cardiac structure and contractility over time, in part via enhanced cytokine signaling. We hypothesized that chronic catecholamine signaling will have a temporal impact on cardiac transcript expression in vivo, in particular cytokines, and that EGFR transactivation plays a role in this process. C57BL/6 mice underwent infusion with vehicle or isoproterenol (Iso)±gefitinib (Gef) for 1 or 2 wk. Cardiac contractility decreased following 2 wk of Iso treatment, while cardiac hypertrophy, fibrosis, and apoptosis were enhanced at both timepoints. Inclusion of Gef preserved contractility, blocked Iso-induced apoptosis, and prevented hypertrophy at the 2-wk timepoint, but caused fibrosis on its own. RNAseq analysis revealed hundreds of cardiac transcripts altered by Iso at each timepoint with subsequent RT-quantitative PCR validation confirming distinct temporal patterns of transcript regulation, including those involved in cardiac remodeling and survival signaling, as well as numerous cytokines. Although Gef infusion alone did not significantly alter cytokine expression, it abrogated the Iso-mediated changes in a majority of the βAR-sensitive cytokines, including CCL2 and TNF-α. Additionally, the impact of βAR-dependent EGFR transactivation on the acute regulation of cytokine transcript expression was assessed in isolated cardiomyocytes and in cardiac fibroblasts, where the majority of Iso-dependent, and EGFR-sensitive, changes in cytokines occurred. Overall, coincident with changes in cardiac structure and contractility, βAR stimulation dynamically alters cardiac transcript expression over time, including numerous cytokines that are regulated via EGFR-dependent signaling.

Proinflammatory cytokines in heart failure: double-edged swords

Increased circulating and intracardiac levels of proinflammatory cytokines have been associated with chronic heart failure. Following an initial insult, the increased production of proinflammatory cytokines, including TNF-α, IL-6, IL-1, and IL-18, jeopardizes the surrounding tissue through propagation of the inflammatory response and direct effects on the cardiac myocyte structure and function. Cardiac myocyte hypertrophy, contractile dysfunction, cardiac myocyte apoptosis, and extracellular matrix remodeling contribute enormously to the development and progression of chronic heart failure. Despite the identification of efficacious pharmacological regimens and introduction of mechanical interventions, chronic heart failure remains among the leading causes of mortality worldwide. To introduce novel therapeutic strategies that modulate the inflammatory response in the context of the failing heart, it is of prime importance to determine the contributions of TNF-α, IL-6, IL-1, and IL-18 in mediating cardiac adaptive and maladaptive responses, as well as delineating their downstream intracellular signaling pathways and their potential therapeutic implications.

Tumor necrosis factor-alpha confers resistance to hypoxic injury in the adult mammalian cardiac myocyte

BACKGROUND

Previous studies in isolated cardiac myocytes have shown that tumor necrosis factor (TNF)-alpha provokes increased expression of 27- and 70-kD stress proteins as well as manganese superoxide dismutase, suggesting that TNF-alpha might play a role in mediating stress responses in the heart.

METHODS AND RESULTS

To determine whether TNF-alpha stimulation would protect isolated cardiac myocytes against environmental stress, myocyte cultures were pretreated with TNF-alpha for 12 hours and then subjected to continuous hypoxic injury (O2 content, 3 to 5 ppm) for 12 hours, followed by reoxygenation. Cell injury was assessed in terms of lactic dehydrogenase (LDH) release, 45Ca2+ uptake, and MTT metabolism. Pretreatment with TNF-alpha concentrations > or = 50 U/mL significantly attenuated LDH release by hypoxic cells compared with diluent-treated hypoxic cells. Similar findings were observed with respect to 45Ca2+ uptake and MTT metabolism in TNF-alpha-pretreated cells that were subjected to prolonged hypoxia. To determine the mechanism for the TNF-alpha-induced protective effect, the cells were pretreated with heat shock protein (HSP) 72 antisense oligonucleotides. These studies showed that the protective effect of TNF-alpha was not inhibited by antisense oligonucleotides, despite use of a concentration of antisense that was sufficient to attenuate the TNF-alpha-induced increase in HSP 72 expression. Subsequent studies using mutated TNF ligands showed that activation of both types 1 and 2 TNF receptors was sufficient to confer a protective response in isolated cardiac myocytes through an as yet unknown pathway(s).

CONCLUSIONS

Taken together, the above observations demonstrate that TNF-alpha pretreatment confers resistance to hypoxic stress in the adult cardiac myocyte through a novel mechanism that appears to be different from but not necessarily exclusive of the protective response conferred by HSP 72 expression.

Tumor necrosis factor-alpha provokes a hypertrophic growth response in adult cardiac myocytes

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) is a pleiotropic cytokine with a broad range of concentration-dependent effects. The recent observation that TNF-alpha is expressed by the cardiac myocyte after certain forms of stress suggests that TNF-alpha might contribute to the maintenance of normal tissue homeostasis after environmental injury. Accordingly, the purpose of this study was to examine the effects of TNF-alpha on protein synthesis in cultured adult cardiac myocytes.

METHODS AND RESULTS

Cultured adult feline cardiac myocytes were stimulated with 10 to 1000 U/mL TNF-alpha to examine the effects of this cytokine on the rate of protein synthesis and degradation. Stimulation with TNF-alpha led to an accelerated rate of general protein synthesis and a time-dependent decrease in protein degradation in adult cardiac myocytes. The specificity of these findings was demonstrated by studies in which the effects of TNF-alpha on protein synthesis were blocked by a neutralizing anti-TNF-alpha antibody as well as studies in which TNF-alpha-conditioned medium had no effect on protein synthesis in myocytes. In addition to the TNF-alpha-induced increase in the general protein synthesis, stimulation with TNF-alpha led to a 2.4-fold increase in net actin protein synthesis and a 3.3-fold increase in net myosin heavy chain synthesis. Finally, the effects of TNF-alpha on adult cardiac myocytes were shown to be dependent on cell-substrate interaction, suggesting that the cell signaling pathways used by TNF-alpha are dependent on a preserved interaction between cell integrins and the extracellular matrix.

CONCLUSIONS

The observation that TNF-alpha provokes a hypertrophic growth response in cardiac myocytes suggests that TNF-alpha may play an important role in myocardial homeostasis after environmental stress.

Correlation of peripheral blood lymphocyte and intragraft cytokine mRNA expression with rejection in orthotopic liver transplantation

BACKGROUND

Regulation of allograft rejection mediated by CD4+ T lymphocytes is dependent on the pattern of cytokines produced by these cells. The purpose of this study was to examine liver transplant recipients to determine whether peripheral blood lymphocyte (PBL), intragraft cytokine production, or both correlated with histologic assessment of graft rejection.

METHODS

PBL and liver biopsy specimens from transplant recipients were examined at varying times after transplantation. Biopsy samples were examined histologically. Messenger RNA was extracted from PBL and liver biopsy specimens and was then amplified by polymerase chain reaction with oligo-specific primer pairs for interleukin (IL)-2, IL-4, IL-6, transforming growth factor-beta, interferon-gamma, and beta-actin.

RESULTS

PBL transcription of IL-2, IL-6, and interferon-gamma was significantly increased in transplant recipients with rejection compared with that in recipients without rejection or healthy individuals who did not undergo transplantation (p < 0.05). Equivalent transcription of IL-4 and transforming growth factor-beta was observed in all patients regardless of rejection status. Graft specimens exhibited quantitative increases in IL-2 and interferon-gamma transcription during rejection with increased IL-4 transcription in the absence of rejection.

CONCLUSIONS

Our data show that specific patterns of peripheral and intragraft cytokine production play a role in the regulation of rejection in liver transplantation.

Tumor necrosis factor-alpha gene and protein expression in adult feline myocardium after endotoxin administration

TNF alpha mRNA and protein biosynthesis were examined in the adult feline heart after stimulation with endotoxin. When freshly isolated hearts were stimulated with endotoxin in vitro, de novo TNF alpha mRNA expression occurred within 30 min, and TNF alpha protein production was detected within 60-75 min; however, TNF alpha mRNA and protein production were not detected in diluent-treated hearts. Immunohistochemical studies localized TNF alpha to endothelial cells, smooth muscle cells, and cardiac myocytes in the endotoxin-treated hearts, whereas TNF alpha immunostaining was absent in the diluent-treated hearts. To determine whether the cardiac myocyte was a source for TNF alpha production, two studies were performed. First, in situ hybridization studies, using highly specific biotinylated probes, demonstrated TNF alpha mRNA in cardiac myocytes from endotoxin-stimulated hearts; in contrast, TNF alpha mRNA was not expressed in myocytes from diluent-treated hearts. Second, TNF alpha protein production was observed when cultured cardiac myocytes were stimulated with endotoxin, whereas TNF alpha protein production was not detected in the diluent-treated cells. The functional significance of the intramyocardial production of TNF alpha was determined by examining cell motion in isolated cardiac myocytes treated with superfusates from endotoxin- and diluent-stimulated hearts. These studies showed that cell motion was depressed in myocytes treated with superfusates from the endotoxin-treated hearts, but was normal with the superfusates from the diluent-treated hearts; moreover, the negative inotropic effects of the superfusates from the endotoxin-treated hearts could be abrogated completely by pretreatment with an anti-TNF alpha antibody. Finally, endotoxin stimulation was also shown to result in the intramyocardial production of TNF alpha mRNA and protein in vivo. Thus, this study shows for the first time that the adult mammalian myocardium synthesizes biologically active TNF alpha.

Cytokine gene expression in human cardiac allograft recipients

The long-term success of heart transplantation for end-stage heart disease has been hindered by the problems associated with acute and chronic graft rejection, opportunistic infections and potentially fatal complications of intensive immunosuppression. A more complete understanding of the biology of transplant rejection should provide the basis for the development of improved methods for controlling and monitoring rejection. Cytokines, the soluble factors which regulate the immune response, are central to the rejection process. The objective of this study was to analyse cytokine mRNA transcripts in 99 biopsy samples and 89 blood samples from 65 and 35 Stanford Medical Center cardiac transplant recipients, respectively, gathered between January 1990 and January 1992. Following RNA extraction and conversion to cDNA, samples were amplified with cytokine-specific primers for interleukins (IL) 1 to 8, TNF-beta (tumour necrosis factor-beta) and IFN-gamma (interferon-gamma) and were analysed by gel electrophoresis and Southern blot hybridization. Our results demonstrate that despite chronic immunosuppressive therapy, the peripheral blood of transplant recipients expressed a higher combined percentage of different cytokine transcripts than did peripheral blood obtained from normal volunteers. In transplant patients, detection of cytokine transcripts for IL-1 alpha, IL-1 beta and IL-2 increased with time after transplantation. Intragraft IL-7 gene expression was significantly increased in biopsies diagnosed with mild (grade 1) rejection when compared to those with no evidence of rejection or with moderate to severe rejection. Implications of these results in light of possible mechanisms of rejection and of new approaches to immunotherapy are discussed.

The effect of interleukin-1 on cytokine gene expression in cultured human articular chondrocytes analyzed by messenger RNA phenotyping

OBJECTIVE

To investigate the pattern of cytokine gene expression in human articular chondrocytes in culture in response to interleukin-1 beta (IL-1 beta). The effect of serum and variations in culture conditions was also studied.

METHODS

Messenger RNA was extracted from cells, reverse-transcribed to complementary DNA, and amplified by the polymerase chain reaction (PCR), using specific oligonucleotide primers. The PCR products were validated by restriction analysis with specific enzymes and by Southern blot analysis.

RESULTS

In cultured articular chondrocytes, IL-1 beta, IL-1 alpha, granulocyte colony-stimulating factor (CSF), and granulocyte-macrophage CSF cytokine genes were expressed only after induction by IL-1 beta. However, IL-6, IL-8, and macrophage CSF genes were expressed constitutively. The expression of IL-1 beta was dose and time dependent.

CONCLUSION

Using PCR, it was possible to demonstrate gene expression for several cytokines in human articular chondrocytes in culture. It was evident that some cytokine genes were expressed constitutively and some were inducible by IL-1 beta.

Tumor necrosis factor-alpha gene expression in the tissues of normal mice

Although TNF-alpha is traditionally associated with macrophage activation during neoplasia and acute inflammation, recent Northern blot hybridization studies indicate that gene expression occurs in the absence of pathology. In order to identify the cellular sources of endogenous message and protein, normal mouse tissues were tested for TNF-alpha mRNA using in situ hybridization and for the corresponding protein by immunocytochemistry. Unexpectedly, specific TNF-alpha message was readily detected in hepatocytes, kidney tubule epithelial cells, various populations of spleen cells and neurons. TNF-alpha protein was present in the same liver and kidney cells as those that contained TNF-alpha mRNA, was low in spleen cells, and was absent in neurons. These results suggest that cells other than macrophages are the major sources of TNF-alpha gene products in normal tissues, indicate that regulation is accomplished by more than one mechanism, and are consistent with the postulate that products of this gene contribute to normal physiological processes.

Specific interferon genes are expressed in individual cells in the peritoneum and bone marrow of normal mice

The use of a highly sensitive method of in situ hybridization capable of detecting one copy of IFN mRNA per cell showed that from 20-50% of the cells from the peritoneum and bone marrow of both normal pathogen-free and axenic mice exhibited grain counts significantly greater than background levels following hybridization with riboprobes specific for the mouse interferon-alpha (IFN-alpha), IFN-beta, or IFN-gamma genes. Labeling was shown to be specific, as the labeled probe was displaced by a 200-fold excess of the specific unlabeled probe but not by a 200-fold excess of an unrelated probe. Grain counts were reduced to background levels when cells were pretreated with ribonuclease prior to in situ hybridization. The extent of labeling with either IFN-alpha or IFN-beta-specific probes increased following i.v. inoculation of mice with the IFN-inducer Newcastle disease virus (NDV) whereas the degree of labeling observed with a probe specific for beta-actin remained unchanged. No significant differences were observed in the number of bone marrow or peritoneal cells that expressed IFN-alpha or IFN-beta mRNA from either high (C57B1/6) or low (BALB/c) IFN-producing strains of mice. The majority of IFN-alpha and IFN-beta-containing cells from both the bone marrow and peritoneum of normal pathogen-free and axenic mice resembled monocytes morphologically, whereas the majority of IFN-gamma mRNA-containing cells resembled small lymphocytes. In addition, in the bone marrow a number of large cells which resembled megacaryocytes were found to express high levels of IFN-alpha mRNA. Nuclear run-on assays showed that IFN-alpha and IFN-beta genes were actively transcribed in both bone marrow and peritoneal cells from normal and axenic mice. Low levels of de novo IFN-gamma RNA synthesis were detected in the nuclei of peritoneal cells only. The expression of IFN genes in individual cells in the tissues of normal animals may constitute a basis for the regulation of both homeostasis and host defense against virus infection and neoplastic cells.

Effects of cytokines on the liver

Cytokines are essential for the communication not only between the liver and extrahepatic sites but also within the liver itself. Cytokines regulate the intermediary metabolism of amino acids, proteins, carbohydrates, lipids and minerals. Cytokines partially interact with classical hormones such as glucocorticoids, resulting in a complex network of mutual control. Since many cytokines exert growth factor-like activities in addition to their specific proinflammatory effects, the distinction between cytokines and growth factors is somewhat artificial. The liver is an important site of synthesis and the major clearance organ for several cytokines. In liver disease, cytokines are involved in the onset of intrahepatic immune responses (e.g., during viral hepatitis), in liver regeneration (e.g., after partial hepatectomy) and in the fibrotic and cirrhotic transformation of the liver such as chronic chemical injury or viral infection. Further studies of cytokine actions may lead to a better understanding of liver diseases and to the development of new immunomodulating therapeutic options.

Genes for interleukin-1, interleukin-6, and tumor necrosis factor are expressed at markedly reduced levels in the livers of patients with severe liver disease

The genes for interferon (IFN) alpha, IFN gamma, IL-1 beta, IL-6, and TNF alpha were transcribed at readily detectable levels both in liver biopsies from individuals with normal liver function and in samples of normal viable liver taken for transplantation. These results provided evidence for the concept that such multifunctional cytokines play a role in homeostasis in normal human tissues. In normal human liver, in situ hybridization studies showed that, in the absence of a detectable inflammatory response, both hepatocytes and mononuclear cells exhibited a similar degree of expression of IL-6 mRNA in keeping with the finding that IL-6 is produced by cells of different lineages. The levels of IL-1, IL-6, and TNF mRNA were found to be markedly reduced in extracts of the livers of patients with primary biliary cirrhosis and other forms of autoimmune liver disease at a time when extensive liver lesions were apparent, compared to the levels of expression of these cytokines in the livers of normal individuals. The reduced expression of IL-1, IL-6, and TNF mRNAs appeared to be a specific effect and not due to a general reduction in RNA synthesis as the IFN alpha, IFN gamma and actin mRNAs were expressed at similar levels in both normal and diseased livers. The levels of IL-1 beta, IL-6, and TNF mRNAs were also reduced in samples of liver from a patient with a drug induced fulminant hepatitis suggesting that this specific pattern of altered cytokine gene expression was characteristic of the advanced stage of severe liver disease.

Rationale for immunotherapy of renal cell carcinoma

Metastasis to distant organs is the principal cause of death from renal cell carcinoma (RCC). No commonly accepted therapy is available for disseminated RCC at present. Immunotherapy is a mode of therapy that either interferes with the immune system or makes use of drugs that have been derived from soluble mediators of the immune system. Several lines of evidence suggest that combinations of genetically engineered cytokines (e.g. interleukin-2 and interferon alpha) may be particularly active in the treatment of advanced RCC. There are two major rationales for considering immunotherapy for RCC: (1) there is currently no other therapy available, and (2) there is hardly any innovative approach besides immunotherapy. Still, immunotherapy is far from being a standard therapy for disseminated RCC.

Anti-tumor effects of interferon in mice injected with interferon-sensitive and interferon-resistant Friend erythroleukemia cells. VIII. Role of the immune system in the inhibition of visceral metastases

DBA/2 mice were injected i.v. with IFN alpha/beta-resistant 3CI8 Friend erythroleukemia cells (FLC) which metastasize to the liver and spleen. IFN alpha/beta treatment of FLC-injected mice increased their survival time and these mice developed a resistance to a second challenge with FLC. The efficacy of IFN alpha/beta in increasing the survival time was compared between normal immunocompetent and immunodeficient mice. The anti-tumor action of IFN was markedly reduced or abolished in newborn DBA/2 mice, in adult athymic nu/nu and beige DBA/2 mice, and in BALB/c scid/scid mice. To determine the phenotype of the effector cells involved, FLC-injected DBA/2 mice were treated with antibodies to asialo-GMI, CD4, or CD8 antigens, or with cyclosporin A or silica. IFN alpha/beta treatment proved much less effective in these mice, indicating that a variety of effector cell types participated in the IFN-induced suppression of visceral metastases. Thus, an intact immune system appears to be essential to obtain optimal therapeutic effects of IFN alpha/beta in this experimental model.