Miodrag L. Lukić

Inhibition of nitric oxide generation affects the induction of diabetes by streptozocin in mice

The experiments reported here indicate that nitric oxide may play an important role in vivo in chemically-induced diabetes mellitus in mice. CBA mice treated with repeated low doses of streptozocin developed sustained hyperglycemia. This was significantly reduced by injections of L-NG-monomethyl-arginine (L-NMMA), a specific inhibitor of the synthesis of nitric oxide, but not affected by the inactive enantiomer, D-NMMA. Histologically the pancreata of animals treated with streptozocin and injected with L-NMMA showed little or no cellular infiltration and significantly lower degrees of islet cell destruction compared to mice treated with streptozocin alone, suggesting that nitric oxide may also be involved in the development of insulitis.

Infiltration of immune T cells in the brain of mice with herpes simplex virus-induced encephalitis

Abstract Herpes simplex virus (HSV) infection of mice can induce viral encephalitis. Using two-fluorochrome immunofluorescence, our present study shows that though there is extensive myelin loss and necrosis in the brain stem of mice with HSV encephalitis, only some oligodendrocytes, astrocytes and microglial cells are infected. T cells that express CD4 or CD8 and a large number of CD4+, F4/80+ macrophages are present in perivascular infiltrates close to and in contact with HSV-infected cells in areas of massive myelin loss. These findings suggest that the resultant infiltration of immune cells into the brain during HSV-1 infection may cause as much damage as the virus itself.

Analysis of T cell subsets after induction of experimental autoimmune encephalomyelitis in susceptible and resistant strains of rats

T cell subsets in the peripheral blood, draining lymph node (DLN) and spinal cord lesions were analysed after the induction of experimental autoimmune encephalomyelitis (EAE) in susceptible (DA) and relatively resistant (AO) rats. In DA rats, a significantly higher number of CD4+ cells were generated in the DLN, in response to both nervous tissue antigens and complete Freunds adjuvant (CFA), compared to AO rats. In the peripheral blood of DA rats, the percentage as well as absolute number of CD4+ cells increased in the preclinical phase of EAE, but declined as the disease developed. The percentage of CD8+ cells decreased in both these phases of EAE. In resistant AO rats, however, there were no significant changes in the T lymphocyte subset percentages after EAE induction, although the absolute number of peripheral blood CD4+ cells again increased in the preclinical stage of EAE. In the CFA-treated control DA rats, the absolute number of CD4+ cells was increased in the preclinical phase. However, no decline comparable to that seen in diseased animals followed. It is concluded that the generation of CD4+ cells in response to this antigen is strain specific and, since the cells are released into the circulation, will affect the balance between the T cell subsets in the peripheral blood during the development of EAE.

Cellular and Genetic Basis of the Relative Resistance to the Induction of Experimental Allergic Encephalomyelitis (EAE) in Albino Oxford (AO) Rats

EAE has been widely studied as a possible model for human demyelinative disease. It can be readily induced in several strains of rats by a single injection of spinal cord or encephalitogenic basic protein emulsified in complete Freund’s adjuvant (CFA). We have previously reported that AO rats always exhibited significantly lower susceptibility to the induction of EAE when compared with Lewis rats (1). In an attempt to delineate the mechanisms of the relative resistance to the induction of EAE in AO rats we studied comparatively the cellular requirements for the induction of EAE in Lewis, AO and Dark August (DA) rats. Further, we have undertaken a study of susceptibility to EAE in AO and DA rats, their F1 hybrids and animals of backcross generations in order to establish possible genetic determinants of the resistance to EAE in AO rats.

The Production of TNF, IL-1 And IL-6 in Cutaneous Tissues During Maturation and Aging

Epithelial cells (EC) resident to cutaneous tissues are important producers of various immunostimulatory, proinflammatory and inhibitory cytokines1,2 Locally produced cytokines in epithelial tissues mediate events relevant to growth, differentiation and function of surrounding cells. Based on their capacity to induce various cell adhesion molecules, as well as “secondary” cytokines,3 they play an important role in intercellular communications. Since immunocompetence of epithelial tissues may be influenced by maturation and aging,4-6 the aim of the present study was to obtain more information on the age-related changes of production of relevant cytokines. To examine this, we investigated age-related expression of TNF, IL-1 and IL-6 by comparing secretory potential of EC normally resident to skin of fetal, neonatal and adult rats.

Resistance to the Induction of T Cell-Mediated Autoimmunity Correlates with Lower IL 2 Production

According to the generally accepted model, IL 2 generated by ligand activated T cells regulates the clonal expansion of antigen-stimulated T cells in a hormonal manner by binding to specific surface receptors on such T cells (1). Because of this central role believed to be played by IL 2 in regulating T cell responses and in view of the importance of IL 2 in the generation of effector cells in experimental allergic encephalomyelitis (EAE) (2) we have analyzed in detail patterns of IL 2 production and consumption by T cells of Albino Oxford (AO) and Dark August (DA) rats previously shown to differ in their susceptibility to EAE (3).

Correlation of IL2 Production and Lymphoid Tissue Make-Up in Two Inbred Strains of Rats

Strain differences in susceptibility to the experimentally induced autoimmunity provide valuable tools for analysing and understanding cellular and genetic deffects leading to autoimmunity in humans. We have shoun that AO and DA inbred strains of rats differ in susceptibility to the induction of several experimental T cell dependent autoimmune diseases, the former being resistant and latter susceptible to these disorders. In search for the cellular basis of the observed differences and in view of the central role played by Interleukin 2 (IL2) in regulating T cell response,we have analysed the pattern of IL2 production in DA and AO strain and found striking difference between these tuo strains (1).Supernatants obtained from ConA stimulated AO lymphocytes revealed louer IL2 activity when compared with preparations derived from DA cells (1). It appeared that a gene not linked to the MHC exerts the major control on the level of IL2 production in this strain combination (2).

Immunoregulation in Epidermis: Glucocorticoids Induced Epidermal Cell Derived Inhibitor of Interleukin 1 Activity

Epidermis, in addition to being a surface barrier, actively participates in various immunologic and inflammatory reactions in the skin. It is already well established that dendritic cells within epidermis such as Langerhans cells may function as antigen presenting cells and thereby play an important role during the initiation of an immune response (1). Among immunologically active elements resident in the epidermis the major cell population is the keratinocytes. They are able to produce several nonspecific immunoregulatory mediators including an immunoenhancing cytokine — epidermal cell (EC) derived thymocyte activating factor — which is indistinguishable from macrophage — derived interleukin 1 (IL 1) (reviewed in 2). We have analyzed recently the accessory cell function of mouse and human epidermal cells (ECs) by measuring their capacity to support the proliferative response of lectin-stimulated nonadherent thymic T cells (NATs)(3). NATs exhibit low responsiveness to lectins, while the addition of ECs induced in a dose-dependent way either supportive or suppressive effects. Having in mind that functional capacity of epidermal cells can be altered by various physico-chemical agents we have analysed the effects of glucocorticoids on the accessory function of epidermal cells. We present here evidence that in vivo exposure of ECs to glucocorticoids not only inhibits the production of IL 1 but also favors the production of factors which suppress NAT proliferation. Additionally we have shown the existence of an immunoinhibitory factor(s) produced by ECs which represent(s) an inhibitor of IL 1 — activity.

CHANGES IN BRAIN CATECHOLAMINES IN EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS

Publisher Summary This chapter discusses a study to analyze changes in brain catecholamines in experimental allergic encephalomyelitis. An attempt was made to establish a pattern of changes in catecholamine level in rats developing EAE; the clinical signs of the disease appeared in 25% of the animals by day 8 and were present in all animals 10 days after the injection of purified basic protein (BP) emulsified in complete Freund adjuvans (CFA). Catecholamines (dopamine and norepinephrine) were chosen for these experiments because of their known role in the process of neurotransmission; hence, neurological deficit might be attributed to the changed levels and/or metabolism of these neurotransmitters. Significant increase in dopamine concentration was found in caudate 10, 12, 14, and 20 days after BP-GFA infection. Changes coincided with the highest index of morbidity. Changes in norepinephrine levels were less striking; among the investigated brain regions (cortex, caudate, thalamus), most prominent changes both in norepinephrine and dopamine were found in caudate. As histological examinations of the brain tissue revealed slight mononuclear infiltration only in meningeal areas and abundance in spinal cord sections, neurochemical finding in the brain tissue could hardly be ascribed to the presence of invading cells.