Thomas K. Hughes

The Interferons: Mechanisms of Action and Clinical Applications

The interferons (IFN) are one of the bodys natural defensive responses to such foreign components as microbes, tumors, and antigens. The IFN response begins with the production of the IFN proteins (alpha, beta, and gamma), which then induce the antiviral, antimicrobial, antitumor, and immunomodulatory actions of IFN. Recent advances have led to Food and Drug Administration approval of five clinical indications for IFN. Interferon alfa is approved for hairy-cell leukemia, condyloma acuminatum, Kaposis sarcoma in the acquired immunodeficiency syndrome, and non-A, non-B (type C) viral hepatitis. Interferon gamma has properties distinctive from those of IFNs alpha and beta and is approved as an immunomodulatory treatment for chronic granulomatous disease. Promising clinical results with IFNs have also been reported for basal cell carcinoma, chronic myelogenous leukemia, cutaneous squamous cell carcinoma, early human immunodeficiency virus infection, hepatitis B, and laryngeal papillomatosis. Future clinical uses of IFNs may emphasize combination therapy with other cytokines, chemotherapy, radiation, surgery, hyperthermia, or hormones.

IL-10 as a mediator in the HPA axis and brain.

Certain functional interactions between the nervous, endocrine, and immune systems are mediated by cytokines. The pro-inflammatory cytokines, interleukin-1 (IL-1) and tumor necrosis factor (TNF) were among the first to be recognized in this regard. A modulator of these cytokines, IL-10, has been shown to have a wide range of activities in the immune system; in this review, we describe its production and actions in the hypothalamic-pituitary-adrenal (HPA) axis. IL-10 is produced in pituitary, hypothalamic, and neural tissues in addition to lymphocytes. IL-10 enhances corticotropin releasing factor (CRF) and corticotropin (ACTH) production in hypothalamic and pituitary tissues, respectively. Further downstream in the HPA axis endogenous IL-10 has the potential to contribute to regulation of glucocorticosteroid production both tonically and following stressors. Our studies and those of others reviewed here indicate that IL-10 may be an important endogenous regulator in HPA axis activity and in CNS pathologies such as multiple sclerosis. Thus, in addition to its more widely recognized role in immunity, IL-10s neuroendocrine activities described here point to its role as an important regulator in communication between the immune and neuroendocrine systems.

Interleukin-10 (cytokine synthesis inhibitory factor) acts in the central nervous system of rats to reduce sleep

Interleukin-10 (IL-10), originally designated a cytokine synthesis inhibitory factor, inhibits the synthesis of the pro-inflammatory cytokines IL-1 and tumor necrosis factor by stimulated human and mouse monocytes/macrophages; these cytokines are involved in the regulation of sleep. To determine if IL-10 reduces spontaneous sleep, we injected murine recombinant IL-10 intracerebroventricularly into rats prior to light onset. Non-rapid eye movements sleep was reduced. The behavioral responses to IL-10 were abolished by heat-inactivation of this cytokine. We believe these to be the first observations of central nervous system actions for this cytokine. These results further support the hypothesis that cytokines are involved in the regulation of sleep, and suggest an additional mechanism whereby sleep may be altered in response to an activated immune system.

Morphine inhibits NF-κB nuclear binding in human neutrophils and monocytes by a nitric oxide-dependent mechanism

Background The transcription factor NF-&kgr;B plays a pivotal role in gene expression of inflammatory mediators such as cytokines or adhesion molecules. NF-&kgr;B–mediated transcriptional activation of these genes is inhibited by nitric oxide (NO) in a variety of cells, including monocytes. Morphine mediates NO release in a naloxone antagonizable manner in monocytes and neutrophils. Methods The influence of morphine on NF-&kgr;B activation was investigated in a whole-blood flow cytometric assay. A specific antibody against the p65 subunit of NF-&kgr;B was used and detected by fluoresceine-isothiocyanate–labeled anti–immunoglobulin G. Nuclei were stained with propidium iodide. Leukocyte subpopulations were evaluated by gating on neutrophils and monocytes. The median fluorescence channel was determined. Different morphine concentrations (50 nm, 50 &mgr;m, 1 mm) and incubation intervals (10–150 min) were used. Results Morphine inhibits lipopolysaccharide-induced NF-&kgr;B nuclear binding in human blood neutrophils and monocytes in a time-, concentration-, and naloxone-sensitive–dependent manner. Similar effects were achieved with the NO donor S-nitroso-N-acetyl-pencillamine and the antioxidant N-acetyl-cysteine. The NO synthase inhibitors N&ohgr;-nitro-l-arginine-methyl-esther and N&ohgr;-nitro-l-arginine completely abolished the morphine-induced attenuation of NF-&kgr;B nuclear binding, demonstrating that the inhibitory action is mediated by NO release. Conclusion Morphine causes immunosuppression, at least in part, via the NO-stimulated depression of NF-&kgr;B nuclear binding.

Interleukin-10 messenger ribonucleic acid in human placenta: implications of a role for interleukin-10 in fetal allograft protection.

OBJECTIVE Our purpose was to determine whether interleukin-10 is expressed in human placental tissue, which might imply a role for it in fetal allograft protection. STUDY DESIGN Detection of interleukin-10 messenger ribonucleic acid in human placental tissue and in human placental JAR cells by reverse transcription-coupled polymerase chain reaction was studied. RESULTS Interleukin-10 messenger ribonucleic acid was detected in human placental tissue from term mothers and in human placental JAR cells. Sequence analysis of the expected interleukin-10 complementary deoxyribonucleic acid fragment revealed 100% homology to authentic interleukin-10 complementary deoxyribonucleic acid. CONCLUSION Our results indicated that human placental tissue from term mothers expressed high levels of interleukin-10 messenger ribonucleic acid, suggesting that cells that produce interleukin-10 and that are associated with the placenta may play a role in preventing rejection of the fetal allograft by the mother.

Suppression of experimental autoimmune myasthenia gravis in IL-10 gene-disrupted mice is associated with reduced B cells and serum cytotoxicity on mouse cell line expressing AChR

To analyze the role of interleukin-10 (IL-10) in experimental autoimmune myasthenia gravis (EAMG) pathogenesis, we induced clinical EAMG in C57BL/6 and IL-10 gene-knockout (KO) mice. IL-10 KO mice had a lower incidence and severity of EAMG, with less muscle acetylcholine receptor (AChR) loss. AChR-immunized IL-10 KO mice showed a significantly higher AChR-specific proliferative response, altered cytokine response, lower number of class II-positive cells and B-cells, but a greater CD5(+)CD19(+) population than C57BL/6 mice. The lower clinical incidence in IL-10 KO could be explained not by a reduction of the quantity, but by a possible difference in the pathogenicity of anti-AChR antibodies.

Opioid induction of immunoreactive interleukin-1 in Mytilus edulis and human immunocytes: an interleukin-1-like substance in invertebrate neural tissue

The synthetic analog of methionine enkephalin, [D-Ala2-Met5]-enkephalin, when administered in vitro to Mytilus edulis ganglia and hemocytes and human peripheral blood lymphocytes, induces the formation of an immunoreactive interleukin-1-like molecule. Additionally, immunoreactive interleukin-1 (IL-1) activity has been found in Mytilus nervous tissue. The stimulatory actions of the extracted immunoreactive IL-1 on Mytilus hemocytes can be antagonized by an IL-1 antibody demonstrating the specificity of the substance. The evidence suggests that the nervous system, via an opioid-IL-1 relationship, can communicate with the immune/defense system through these similar signal molecules. Furthermore, the results indicate that an interleukin-like molecule must have evolved earlier than previously thought.

δ2 opioid receptor subtype on human vascular endothelium uncouples morphine stimulated nitric oxide release

Abstract We demonstrate the presence of both δ and μ opioid receptors on the endothelium of human saphenous vein and internal thoracic artery. Displacement analysis revealed that a variety of opioid peptides were found to be ineffective in displacing specifically bound 3 H dihydromorphine and only δ 2 ligands were effective in regard to 3 H Ala 2 -met 5 enkephalinamide (DAMA), indicating the presence of μ 3 and δ 2 opioid receptor sites, respectively. Confirming the presence of both μ and δ sites we demonstrated positive immunostaining with anti-δ and anti-μ receptor antibodies. Exposure of these vessels to DAMA significantly enhances granulocyte adherence ( P −6 M morphine. Unlike morphine, DAMA did not stimulate nitric oxide from either blood vessel and human granulocytes. Additionally, DAMA preadministered before morphine exposure to the endothelium or granulocytes, inhibited the morphine-stimulated release of NO in a dose-dependent manner. The data indicate that opioid peptides and opiate alkaloids regulate endothelial function in an antagonistic manner thereby influencing the microvascular environment.

Modulation of immune responses by anabolic androgenic steroids

Anabolic androgenic steroids (AS) have recently been placed on the Food and Drug Administrations (FDAs) list of controlled substances, because of the adverse effects seen in athletes taking accelerated dosages in attempts to enhance performance. Reported deleterious effects on abusers include sterility, gynecomastia in males, acne, balding, psychological changes, and increased risks of heart disease and liver neoplasia. Considering the roles of the immune and neuroendocrine systems and their interactions in many of these pathologies, it is important to determine the effects of these derivitized androgens on this connection. Little is known in this respect. We therefore determined the effects of anabolic steroids on certain immune responses and their effects on the extrapituitary production of corticotropin by lymphocytes. We present evidence that (1) both 17-beta and 17-alpha esterified AS, nandrolone decanoate and oxymethenelone, respectively, significantly inhibited production of antibody to sheep red blood cells in a murine abuse model; (2) the control androgens testosterone and dehydroepian-drosterone (DHEA) or sesame seed oil vehicle had no significant effects on antibody production; (3) nandrolone decanoate and oxymethenelone directly induced the production of the inflammatory cytokines IL-1 beta and TNF-alpha from human peripheral blood lymphocytes but had no effect on IL-2 or IL-10 production; (4) control androgens had no direct cytokine inducing effect; (5) nandrolone decanoate significantly inhibited IFN production in human WISH and murine L-929 cells; and (6) nandrolone decanoate significantly inhibited the production of corticotropin in human peripheral blood lymphocytes following viral infection. These data indicate that high doses of anabolic steroids can have significant effects on immune responses and extrapituitary production of corticotropin. Furthermore, the mouse model should provide an effective means by which to study other deleterious effects of anabolic steroid abuse in humans.

Modulation of voltage-activated ion currents on identified neurons of Helix pomatia L. by interleukin-1

Summary1.The effect of interleukin-1 (IL-1) was studied on voltage-activated ion currents of the identified central neurons ofHelix pomatia L. using a twomicroelectrode voltage clamp. The voltage-activated inward current (ICa) was decreased, whereas the outward current (Inet K) was increased by IL-1.2.IL-1 affects both the transient and the delayed rectifying potassium currents. The IL-1 modulatory effect on the voltage-activated ion currents was voltage and dose dependent. The threshold concentration for IL-1 was 2 U/ml.3.The proposed modulatory effect of IL-1 appears to have more than one site of action on the neuron membrane ion channels.4.Rabbit anti-human IL-1 polyclonal antiserum eliminated the IL-1 effects on the voltage-activated inward and outward currents. This is the first report demonstrating a direct effect of IL-1 modulation of voltage-activated ion currents on neurons of mollusks.