Lymphokines and the brain

Fundamentals of the modern theory of the phenomenon of “pain” in terms of a systematic approach to issues its psychological component. Terminology of the systemic approach and a brief representation of the human body as a system

“Pain” is psychophysiological phenomenon, that is actualized in the mind of a person as a result of a systemic reaction to a certain externaland internal stimuli. The pain is caused by morphological and functional disorders in the body and is accompanied by changes in person’s psychic stateand behavior. Three components are distinguished in the phenomenon of “pain”: nocigenic (somatogenic), neurogenic (neuropathic) and psychogenic.The psychical and physiological components are distinguished only within emotions and sensations among all mental processes. The formationof connections and relationships between their components occurs on the basis of neurophysiological processes. Emotions and feelingsof a person are inseparably linked with the corresponding physiological processes of the body, which, in turn, are a reflection of a certainform of the systemic structural and functional organization.From the point of view of the functional system approach, the human body is an exposed, nonlinear, self-organizing, self-regulating,self-learning, permanently evolving, dynamic system that exists in inseparable connection and constant interaction with the environment.Elements of its systemic structural and functional organization are certain functional systems of the corresponding hierarchical levels.Regulatory centers are one of the main elements of the human organism’s functional systems, their activities realize the processes of theirself-organization and self-regulation. In functional systems at the cellular, tissue, organ and organism levels of its systemic organization,the regulatory centers are the neuronal-synaptic organizations of the structural formations of the peripheral and central nervous system.Nervous system of the person integrates and coordinates the processes of sensitivity, activity of its effector structure formations andmotion activity, accordingly to the conditions of its internal and external environment. Realization of its functions as a whole and infull is possible only in inseparable interrelation and mutual relation, coordinated interaction and interconsistency with endocrine andimmune-competent systems. The ways and means of intercellular communication are the basis for the processes of integration and coordinationof the activity of effector and structural formations of the human body.

Transforming growth factor-beta 1 differentially regulates proliferation and MHC class-II antigen expression in forebrain and brainstem astrocyte primary cultures

To facilitate investigation of cytokine regulation of reactive astrogliosis, primary astrocyte cultures from neonatal murine forebrain and brainstem were established. Forebrain and brainstem astrocytes proliferated at a similar rate under basal culture conditions, and both were growth-inhibited by treatment with recombinant murine interferon-gamma. The growth of cultured brainstem astrocytes was significantly enhanced by exposure to recombinant human transforming growth factor-beta 1. In contrast, proliferation of forebrain astrocytes was not significantly affected by transforming growth factor-beta 1. The disparate responses of brainstem and forebrain astrocytes to transforming growth factor-beta 1 treatment were not limited to effects on cell growth, since transforming growth factor-beta 1 could block interferon-gamma-induced MHC class-II antigen expression on cultured brainstem astrocytes but not on forebrain cells. Results could not be attributed to use of an heterologous cytokine/cellular target system, since similar variability in transforming growth factor-beta 1 modulation of major histocompatibility complex antigen expression could be demonstrated using two human astrocytoma cell lines. This report is the first to document mitogenic response to transforming growth factor-beta 1 for neuroepithelial cells. The role of transforming growth factor-beta 1 in regulating aspects of reactive astrogliosis, particularly in the context of inflammatory demyelination, requires further investigation. Furthermore, these studies may provide insight into regional variability in the sequelae of inflammation within the central nervous system.

Autoimmune inflammation of astrocyte transplants

Astrocytes have been shown to be capable of serving as antigen-presenting cells and as targets for encephalitogenic cytotoxic T lymphocytes. The role of astrocytes in central nervous system (CNS) autoimmune inflammation is unclear. To study this further, we transplanted astrocyte aggregates into the anterior eye chamber of the mouse. The astrocytic nature of these transplants was confirmed by immunohistochemical detection of glial fibrillary acidic protein and the inability to detect oligodendrocyte or microglial markers. When mice bearing transplants were induced to develop experimental allergic encephalomyelitis by either passive or active protocols, the astrocyte transplants developed a perivascular inflammatory response similar to that seen in the host CNS during the course of the encephalomyelitis. The data suggest that astrocytes could serve as targets for the autoimmune attack of experimental allergic encephalomyelitis and support the possibility that the pathogenesis of this disease may involve an autoimmune reaction against a site other than the myelin sheath.

Multiple sclerosis: a pivotal role for the T cell in lesion development

The recognition of an increasing number of similarities between the immunologic anomalies associated with multiple sclerosis (MS) and the T cell-mediated demyelinating model, experimental autoimmune encephalomyelitis (EAE), has resulted in considerable focusing of investigative approaches. It appears that irrespective of the elucidation of the nature of the putative aetiological factor (presumed to be viral) in MS, the arrest and reversal of T cell-related events within the CNS in this devastating condition represent feasible goals and should remain a major target for some time to come. This short review summarizes the current major areas of activity as they relate to T cell involvement in the immunopathology of MS (and EAE) and presents them in the context of potential therapeutic relevance. In the light of laboratory experiments in which ablation or counteraction of the inflammatory response within the central nervous system (CNS) appears to lead to cessation of immune-mediated disease and encouragement of CNS remyelination, the prospects of similar strategies being applied to MS are becoming increasingly strong.

Chick sympathetic neurons in culture respond differentially to nerve growth factor and conditioned medium from activated splenic lymphocytes

Chicken splenic cells, stimulated by concanavalin A, secreted a factor or factors into the culture medium which supported the survival of neurons from sympathetic ganglia of chick embryos. The effect of this conditioned medium (CM) was similar to the effect of nerve growth factor (NGF). However, the enhanced survival effect of CM was unaffected by K-252a, a protein kinase inhibitor which completely abolished the effect of NGF. 6-Thioguanine, an inhibitor of NGF-activated protein kinase N, blocked the survival effects of both NGF and CM on sympathetic neurons, but a dose required for the half-maximal inhibition for the survival effect of CM was 10 times higher than that for NGF. H-7, an inhibitor of protein kinase C, did not block the effect of either CM or NGF. On the other hand, the survival effect of both CM and NGF was blocked to the same extent by 5'-deoxy-5'-methylthioadenosine and LiCl. These results suggest that activated splenic cells secreted neuronal survival-promoting factor(s) into CM and that the cellular mechanisms promoting neuronal survival by CM are different from those promoting neuronal survival induced by NGF.

Interleukin 2 receptor beta chain expressed in an oligodendroglioma line binds interleukin 2 and delivers growth signal

Interleukin 2 (IL-2) is a potent growth factor for T lymphocytes, playing a crucial role in the immune response. In view of the considerable evidence that the immunoregulatory cytokines (or lymphokines) also play a role in the growth and differentiation of cells in the central nervous system (CNS), we examined the operation of the IL-2 system in a cell line of CNS origin by expressing a cDNA encoding the beta chain of the human IL-2 receptor (IL-2R beta, a 75-kDa protein). When the cDNA was expressed in a human oligodendroglioma cell line, ONS-21, the IL-2R beta bound IL-2 with an affinity similar to that in lymphoid cells (Kd, approximately 2 nM). Furthermore, cell proliferation ([3H]thymidine incorporation) was stimulated by IL-2. These results demonstrate that the same cytokine receptor is functional in cells of the immune system and CNS and point to a molecular mechanism that is similar for growth-signal transduction between lymphoid and neural cells but that may be different in other cells, such as fibroblasts.

Immunotherapy for malignant glioma using human recombinant interleukin-2 and activated autologous lymphocytes. A review of pre-clinical and clinical investigations

Over the past few years, we and a number of other groups have conducted laboratory experiments and clinical trials of human recombinant interleukin-2 (rIL-2) alone or in combination with autologous 'activated' lymphocytes expressing in vitro tumoricidal activity in order to define toxicity and indicate its potential efficacy in patients with high-grade glioma. Because high rIL-2 concentrations can be attained with considerably less toxicity than with a systemic approach, all of the clinical trials, to date, have chosen a direct route; injecting lymphokine and cells into tumor tissue, the cystic cavity remaining after tumor excision, and/or neural parenchyma surrounding the site of tumor excision. While the rIL-2 therapies, as they have been applied in animal glioma models and patients, are safe, cerebral edema around the site of treatment has been a consistent finding. We have also seen, however, that steroid medications used by patients to control their cerebral edema may depress the anti-tumor activity of rIL-2 by depressing the capacity of lymphocytes to develop normal LAK activity. Although none of the immunotherapies involving rIL-2 have produced cures, the fact that sustained clinical responses have been reported, suggests that such therapies may slow a recurrence of tumor at the site of treatment. Efforts to improve outcome from rIL-2--based immunotherapies for malignant glioma are continuing with manipulation of rIL-2 dosing and scheduling and also with combinations of rIL-2 and other recombinant cytokines.

Calmodulin-dependent enzymes as a target of staphylococcal enterotoxin A

The response of lymphoid and nerve cells to the action of SEA has been investigated. It has been established that the toxin acts as a mitogen with respect to resting cells and suppresses the DNA biosynthesis in proliferating cells. Interaction of SEA with the systems of second messengers in lymphoblastoid cells has been studied. The results obtained suggest a mechanism of the antiproliferative action of SEA on these cells. Studies on the structural organization of the toxin molecule have revealed that the latter contains a polypeptide (BacM) capable of activating calmodulin-dependent enzymes both in the presence and absence of Ca2+. These findings permit us to assume that the cytostatic effect of SEA is conditioned by the formation of BacM and phosphorylation of elongation factor 2.

Immunology of central nervous system tumors

With progress in cellular immunology and the development of hybridoma technology, the idea of manipulating host-tumor immune interactions to improve the prognosis of brain tumors has aroused renewed interest. Although no brain tumor-specific antigens have been found, and in spite of the wide antigenic heterogeneity of brain tumor cells, some monoclonal antibodies possessing restricted specificity have been isolated and their potential clinical applications investigated. One of the most pronounced changes in the cellular immune responses of brain tumor patients is a profound depression of the T4-helper lymphocytes. Clinical and laboratory trials are under way to assess the ability of lymphokines, such as gamma-interferon or interleukin-2, to restore immunologic competence in these patients and potentiate a specific anti-tumor immunologic response. Recent work suggests that the endothelium-astrocyte complex may have a pivotal role in assisting the escape of brain tumors from the host's immunologic responses, since it is responsible for the intracerebral sequestration of antigens and local anti-tumor responses. In this review, the data on the antigenic properties of central nervous system tumors and the host's humoral and cellular immune responses to them are analyzed and potential immunologic therapies are discussed.

Shared recognition molecules in the brain and lymphoid tissues: the polypeptide mediator network of psychoneuroimmunology

Nervous and immune systems share specific recognition molecules for signals that originate in both systems. The information substances are polypeptides and their receptors. They comprise the multi-directional information exchange network whereby brain and nervous system function including mood and emotion can be integrated with immune and endocrine system activity throughout the body. This serves as a biochemical rationale for multiple interactions between the systems. It permits us at the tissue, cellular and molecular level to start to understand the "psychoneuroimmunology" of the whole person. Initiated changes in our view of the nervous and immune systems will undoubtedly lead to new strategies for the prophylaxis, diagnosis and treatment of human pathology.

Genomic sequence for human prointerleukin 1 beta: possible evolution from a reverse transcribed prointerleukin 1 alpha gene

We have isolated the human prointerleukin 1 (proIL-1) beta gene from leukocyte and fetal liver libraries. The nucleotide sequence and its gene organization reveals that the proIL-1 beta gene is composed of seven exons with a primary transcription product length of 7,008 nucleotides. The exon sequence agrees well with that of the human proIL-1 beta cDNA. Features of interest within the transcriptional unit include positioned TATA, CAT, and poly-adenylation signals for gene regulation, as well as the signatures of gene duplication via retrotransposition in the form of flanking direct repeats and a genomic poly A tail. The genomic organization of the proIL-1 beta gene with respect to the number and position of exon boundaries is strikingly similar to that of the recently reported human proIL-1 alpha gene. Therefore, we hypothesize that the proIL-1 beta may have arisen by a reverse transcriptase mediated duplication of the related alpha gene.

Myelopeptides--bone marrow mediators with immunostimulating and endorphin-like activity

Bone marrow cells produce soluble mediators with structural and functional heterogeneity. They were found to stimulate antibody production at the peak of the immune response, owing to compounds of a peptide nature (Mr 2000-1300). Active material was isolated by means of gel chromatography and electrophoresis. This material positively reacts with ninhydrin, and has maximum absorption close to 278 nm. Its antibody-stimulating activity decreased or stopped completely after treatment with proteolytic enzymes. Apart from the immunostimulating activity, bone marrow mediators have opiate-like activity. They have an analgetic effect, and interact with the opiate receptors of brain nerve cells. After a physicochemical and functional analysis, we conclude that bone marrow produces regulatory peptides that were previously unknown. We called them myelopeptides.