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K Selmaj

Publications and source records attributed to K Selmaj.

At least 37 records · Page 2Linked to original sources
PubMed1991

Cytokine cytotoxicity against oligodendrocytes. Apoptosis induced by lymphotoxin.

The cytotoxic effect of recombinant human cytokines was tested on glial cells cultured from mature bovine brain. Lymphotoxin (LT) and TNF induced injury to oligodendrocytes in a time and dose-dependent fashion. The other cytokines tested, IFN-gamma, IL-6, and IL-2, did not affect oligodendrocytes in culture over a 72-h observation period. None of the cytokines injured astrocytes cultured from the same source. LT showed a much more potent cytotoxicity than TNF toward oligodendrocytes; cytotoxic changes were noted earlier (24 h) and at lower units of activity. Morphologic studies showed that the LT-mediated effects were associated with early retraction of cell processes, depolymerization of F-actin and subsequent nuclear degeneration. Lack of early cytoplasmic membrane injury as measured by 51Cr release and electron microscope studies demonstrating nuclear disintegration suggested an apoptotic mechanism of oligodendrocyte injury evoked by LT, which was supported by DNA integrity assay. These results demonstrate that LT possesses potent cytotoxic activity against oligodendrocytes and that the major mechanism involved in this process is DNA fragmentation.

Actins↗
PubMed1991

Colocalization of lymphocytes bearing gamma delta T-cell receptor and heat shock protein hsp65+ oligodendrocytes in multiple sclerosis.

The presence of T lymphocytes bearing the gamma delta T-cell receptor (TCR gamma delta) has been studied immunocyto-chemically in central nervous system (CNS) tissue from 13 patients with multiple sclerosis (MS), 4 with inflammatory non-MS CNS disorders, 6 with other neurological diseases, and 3 with nonneurologic conditions. Twenty-eight of 43 MS lesions contained TCR gamma delta cells and these were most frequently found in chronically demyelinated areas, in contrast to the previously studied CD4+, CD8+ (TCR alpha beta) population, which predominated in more active lesions. Some TCR gamma delta lymphocytes had an unusual morphology with long dendritic processes, which were sometimes interconnected forming a network. Because it is generally believed that TCR gamma delta lymphocytes function in a cytotoxic fashion in association with heat shock proteins (hsp), we examined the colocalization of TCR gamma delta cells with 65- and 70-kDa hsp (hsp65 and hsp70) in MS lesions. Hsp65 was expressed on immature oligodendrocytes at the margins of chronic lesions containing TCR gamma delta lymphocytes. The coexpression of these molecules might imply functional relationships perhaps of significance to the chronicity of the MS disease process and the failure of CNS remyelination.

Antibodies, Monoclonal↗
PubMed1991

Anti-tumor necrosis factor therapy abrogates autoimmune demyelination.

To define a role for the cytokine tumor necrosis factor (TNF) in immune-mediated demyelination, the effect of anti-TNF antibody was investigated with a form of experimental autoimmune encephalomyelitis (EAE) in SJL/J mice induced by the adoptive transfer of myelin basic protein-(MBP)-sensitized T lymphocytes, an animal model of the human disease multiple sclerosis (MS). In three separate experiments, no mouse sensitized for EAE and then treated with anti-TNF by intraperitoneal injection developed signs of central nervous system (CNS) disease. Examination of CNS tissue from anti-TNF-treated animals showed no pathological changes. CNS tissue from control animals demonstrated extensive inflammatory cell infiltration and demyelination. To test whether anti-TNF therapy was inhibitory to encephalitogenic cells, preincubation of MBP-sensitized T lymphocytes with anti-TNF in vitro prior to injection into recipient mice was performed, and resulted in no diminution of their ability to transfer EAE. In addition, spleen cells from anti-TNF-treated mice were capable of serial transfer of EAE, similar to spleen cells from control animals. However, spleen cells from anti-TNF-treated mice did not produce TNF on stimulation with MBP or concanavalin A. This study showed that anti-TNF antibody can inhibit effectively the development of EAE by interfering with the effector, rather than the induction, phase of the disease. Anticytokine therapy may have important applications in the development of new therapeutic strategies for MS.

Animals↗
PubMed1991

Non-specific oligodendrocyte cytotoxicity mediated by soluble products of activated T cell lines.

Supernates from myelin basic protein (MBP)-reactive T cell lines have been tested by a battery of assays for cytotoxicity against oligodendrocytes in vitro. All supernates tested demonstrated cytotoxic activity in both a dose- and time-dependent manner that ranged from 29.1% to 55.8% after 48 h incubation. Oligodendrocyte cytotoxicity mediated by MBP-reactive T cell lines was not antigen specific since lines reactive with purified protein derivative (PPD) of tuberculin showed similar cytotoxicity. Supernates cytotoxic to oligodendrocytes were equally effective against syngeneic and non-syngeneic target cells, but had no effect upon astrocytes. Neutralization studies revealed that oligodendrocyte cytotoxicity mediated by MBP-reactive T cell supernates could only be partially attributed to lymphotoxin/tumor necrosis factor activity, and was not associated with perforin, serine proteinase or N-methyl-D-aspartate (NMDA) receptor agonists.

Animals↗
PubMed1991

Tumor necrosis factor-induced proliferation of astrocytes from mature brain is associated with down-regulation of glial fibrillary acidic protein mRNA.

Previous results from this laboratory have shown that tumor necrosis factor (TNF) is mitogenic for bovine astrocytes in chemically defined (CD) medium. The maximum mitogenic response was detected with 200 U/ml at 48 h. We have now extended these studies to assess the effect of TNF on message levels for the intermediate filament proteins glial fibrillary acidic protein (GFAP) and vimentin. The results have shown that, whereas TNF had only a slight effect on vimentin mRNA, TNF induced a marked decrease to 4.3 +/- 2.0% of controls in GFAP mRNA which was both time and dose dependent. The lowest effective dose was 50 U/ml and the maximal effective dose was 200 U/ml. Kinetic analysis of this response demonstrated that a marked decrease in GFAP mRNA was present at 12 h and continued to decrease through 72 h. To determine the reversibility of the TNF effect, astrocyte cultures were exposed to 200 U/ml TNF for varying periods of time and then cultured in fresh CD medium. A 1-h pulse with TNF was sufficient to reduce GFAP mRNA levels when measured 24 h later. However, cultures incubated with 200 U/ml TNF for 48 h followed by incubation in CD medium without TNF for 7 days showed that GFAP mRNA levels had returned to 60% of the control values. Nuclear runoff assays showed that the effect of TNF on GFAP mRNA was at the posttranscriptional level. Polyacrylamide gel electrophoretic analysis of astrocyte cytoskeletal proteins demonstrated that GFAP levels were reduced after a 5-day incubation with 200 U/ml TNF whereas protein levels of vimentin and actin were not significantly changed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Identification of lymphotoxin and tumor necrosis factor in multiple sclerosis lesions.

Multiple sclerosis (MS) brain tissue, spleen, and PBMC were studied using immunocytochemistry and FACS for immunoreactivity for lymphotoxin (LT) and TNF. Both cytokines were identified in acute and chronic active MS lesions but were absent from chronic silent lesions. LT was associated with CD3+ lymphocytes and Leu-M5+ microglia cells at the lesion edge and to a lesser extent, in adjacent white matter. TNF was associated with astrocytes in all areas of the lesion, and with foamy macrophages in the center of the active lesion. In acute lesions, immunoreactivity for TNF in endothelial cells was noted at the lesion edge. No LT or TNF reactivity was detected in Alzheimer's or Parkinson's disease brain tissues but was present at lower levels in central nervous system (CNS) tissue from other inflammatory conditions, except for adrenoleucodystrophy which displayed high levels of LT in microglia. No increase in LT and TNF reactivity was detected in spleen and PBMC of MS patients suggesting specific reactivity within the CNS. These results indicate that LT and TNF may be involved in the immunopathogenesis of MS, and can be detected in both inflammatory cells and cells endogenous to the CNS.

Acute Disease↗
PubMed1991

Lymphotoxin production in multiple sclerosis patients.

Lymphotoxin (LT) is a cytotoxic and cytostatic lymphokine produced by activated T and B lymphocytes. Recently, the influence of cytokines on the pathomechanism of demyelinization was investigated. The authors studied LT production in the multiple sclerosis patients. The control group were patients with other neurologic diseases. Spontaneous LT production by T lymphocytes in multiple sclerosis patients was statistically increased during relapse in comparison with the LT production in OND patients. Despite of mitogen stimulation T and B lymphocytes from MS patients produced gradually decreased amounts of LT. The authors suggest that LT might be the product of activated lymphocytes that cause demyelinization during multiple sclerosis.

Adult↗
PubMed1989

Preliminary studies of cytokine-induced functional effects on the visual pathways in the rabbit.

Epidural visual evoked potentials (VEP) were used to study the role of cytokines in the induction of pathophysiologic changes associated with inflammation in the central nervous system (CNS) of the rabbit. In normal rabbits, intraocular injection of human recombinant interferon-gamma (IFN-gamma) and tumor necrosis factor (TNF) increased the peak latency of the cortical VEP by more than 2 ms within 3 h of injection; equal volume injections of control substances had no effect. Alterations in conduction induced by IFN-gamma and TNF reversed within 24 h and could be reinduced by reinjection. Intraocular injection of recombinant human interleukin-1 beta (IL-1) induced a more progressive delay in conduction that peaked 24 h after intraocular challenge and reversed over the ensuing 48 h. Pathologic examination of the tissues indicated that the primary effect of these cytokines is on the vasculature and induces changes associated with inflammation. The results suggest that the acute reversible effects of cytokines on CNS function are associated with vascular events; further they support the sensitivity of the 'rabbit eye model' for studies on the pathophysiologic effect of inflammatory mediators on the CNS in vivo.

Animals↗
PubMed1988

Interleukin-1 and interleukin-2 production by peripheral blood mononuclear cells in multiple sclerosis patients.

The production of interleukin-1 (IL-1) and interleukin-2 (IL-2) by peripheral blood mononuclear cells (PBM) was assessed in multiple sclerosis (MS) patients in relapse, chronic progressive MS patients, patients with other neurological diseases (OND) and healthy subjects. Production was defined as the level of IL-1 and IL-2 in PBM supernatants. Neither spontaneous nor LPS-induced IL-1 production differed significantly in MS, OND patients or healthy individuals. On the other hand PHA-induced PBM IL-2 production was significantly less in MS patients in relapse (130 +/- 10.0 U/ml) than in chronic progressive MS patients (172 +/- 9.8 U/ml), OND patients (192 +/- 11.5 U/ml) and healthy subjects (215 +/- 13.8 U/ml) (P less than 0.02). Spontaneous IL-2 production was also diminished in MS patients in relapse (31 +/- 7.2 U/ml) as compared to chronic progressive MS patients (46 +/- 8.8 U/ml) and healthy subjects (49 +/- 11.1 U/ml) (P less than 0.01). Anti-Tac monoclonal antibody was used to study IL-2 receptor expression on the same sample of PBM that was used for IL-2 study. MS patients in relapse had significantly higher levels of IL-2 receptor-positive unstimulated PBM (6.0 +/- 2.2%) as compared to chronic progressive MS (2.0 +/- 0.9%), OND (2.5 +/- 1.1%) and healthy subjects (1.5 +/- 0.7%) (P less than 0.002). We postulate that reduced apparent IL-2 production by PBM of MS patients in relapse may result from immediate IL-2 binding to receptor expressed on activated T lymphocytes and internalization of IL-2-receptor complex.

Adult↗
PubMed1988

Multiple sclerosis: effects of activated T-lymphocyte-derived products on organ cultures of nervous tissue.

Supernatants from multiple sclerosis (MS) T-lymphocytes cause damage to both myelin and glial cells in cerebellar cultures assessed visually and by radiolabel release. Control T-lymphocytes, even after phytohaemagglutinin (PHA) stimulation, yielded supernatants which induced only slight damage, and at later times patients with other neurological diseases (OND) gave variable results. These differences suggest that MS T-lymphocytes are pre-activated in vivo to produce demyelinating factors while control T-lymphocytes are not pre-activated to the same extent. The visual evidence of activation of cerebellar macrophage-like cells was a common finding after MS T-lymphocyte supernatant treatment but there was no correlation with the severity of demyelination. There was a positive correlation between the percentage IL-2 receptor-bearing lymphocytes and the degree of supernatant-induced in vitro demyelination.

B-Lymphocytes↗
PubMed1988

Multiple sclerosis: effect of myelin basic protein on interleukin 1, interleukin 2 production and interleukin 2 receptor expression in vitro.

The production of interleukin 1 (IL-1) and interleukin 2 (IL-2) by peripheral blood mononuclear cells (PBMC) stimulated with human myelin basic protein (MBP) was assessed in vitro in multiple sclerosis (MS) patients in relapse, patients with other neurological diseases (OND) and healthy subjects. Myelin basic protein significantly increased both IL-1 and IL-2 production by PBMC from MS patients during relapse when compared to OND patients or healthy controls. The most efficient concentration of MBP for the induction of IL-1 and IL-2 was 50 micrograms/ml. The optimal IL-1 production occurred after 48 h of PBMC culture and optimal IL-2 production after 72 h of PBMC culture. Anti-Tac monoclonal antibody (MoAb) was used to study IL-2 receptor expression on the same sample of PBM used for IL-2 study in MS patients in relapse. In addition IL-2 receptor expression was studied in PBMC from chronic progressive MS patients. In both MS groups IL-2 receptor expression on PBMC stimulated with MBP appeared higher than in control groups, but these differences were not statistically significant. IL-2 receptor expression on cerebrospinal fluid lymphocytes (CSF-L) either unstimulated or MBP-stimulated was, however, significantly higher in both MS groups when compared to OND patients. These results confirm the presence of activated lymphocytes in the CSF of MS patients during active stages of disease and suggest that this activation may be related to expansion of MBP specific cells.

Adult↗
PubMed1987

T lymphocyte-derived demyelinating activity in multiple sclerosis patients in relapse.

Supernatants of cultured T lymphocytes of multiple sclerosis patients were tested for a demyelinating activity in rat cerebellum explant cultures. Supernatants of unstimulated T lymphocytes in seven out of 10 multiple sclerosis patients in relapse produced demyelination when checked by phase contrast microscopy. Supernatants of unstimulated T lymphocytes from healthy subjects did not produce demyelination, but when T cells were stimulated by phytohaemagglutinin (PHA), 50% of tested supernatants produced demyelination, which was, however, never as advanced as in multiple sclerosis supernatant treated cerebellum cultures. The demyelinating activity proved to be heat labile. Gel filtration study revealed two fractions of the demyelinating activity 12.5-29.0 kD and 43.0-66.0 kD. The results suggest that lymphokines can be directly involved in the pathogenesis of demyelination in multiple sclerosis.

Adult↗
PubMed1987

The effect of granulocyte factor (GF) on the production of interleukins and Tac antigen expression.

In the course of adherence granulocytes secrete the granulocyte factor (GF) which modifies lymphocyte functions in vitro. GF augments the interleukins production and diminishes mitogen induced Tac antigen expression in vitro, which may result in diminished IL-2 utilization. Consequently, such cells probably do not absorb IL-2 and do not exert their "inhibitory" potency measured in two step culture. The presented data show a relative deficit in interleukin generation in RA patients and have suggested the role of granulocytes in immunoregulation presumably in the course of diseases accompanied by inflammatory processes.

Adult↗