Biomedical subjects

M Mustafa

Publications and source records attributed to M Mustafa.

At least 37 records · Page 2Linked to original sources

PubMed1999

Quantitative genetic variation for oviposition preference with respect to phenylthiocarbamide in Drosophila melanogaster.

Seven isogenic strains of Drosophila melanogaster were assayed for oviposition preference on food with phenylthiocarbamide (PTC) versus plain food. There was significant variation among strains for the percentage of eggs oviposited on each medium, ranging from 70 +/- 4% (SE) preference for plain food to no significant preference. Reciprocal hybrid, backcross, and F2 generations derived from two extreme parent strains revealed significant additive and nonadditive genetic variation but no evidence of maternal, paternal, or sex-chromosome effects.

Animals↗

PubMed1999

Levels of interleukin-15-expressing blood mononuclear cells are elevated in multiple sclerosis.

Interleukin-15 (IL-15) is a novel IL-2-like cytokine expressed by cells of the monocyte/macrophage and epithelial lineages. Cytokines might be involved in the pathogenesis of multiple sclerosis (MS). Using immunocytochemistry, we analysed spontaneous expression of IL-15 by peripheral blood (PB) and cerebrospinal fluid (CSF) mononuclear cells (MNC) from patients with MS, other neurological diseases (OND) and healthy controls. IL-15- positive peripheral blood mononuclear cells (PBMNC) were elevated in patients with MS compared to healthy controls (P < 0.05). The elevation of IL-15- positive PBMNC was restricted to patients with chronic progressive MS and not observed in patients studied during the relapsing-remitting phase of MS. The numbers of IL-15- expressing PBMNC correlated with the duration and disability of MS (r = 0.45, P < 0.001, and r = 0.39, P < 0.01, respectively). IL-15 was undetectable in CSF MNC, and ELISA showed low CSF levels of IL-15 in occasional patients with MS and OND. IL-15 is a potent growth factor for gammadelta T cells, but there was no correlation between IL-15 expression by PBMNC and percentage of gammadelta T cells in blood from the MS patients. Together, these data demonstrate that IL-15 expression by PBMNC is upregulated in the chronic stage of MS.

Adolescent↗

PubMed1999

Hypophysectomy enhances interleukin-1beta, tumor necrosis factor-alpha, and interleukin-10 mRNA expression in the rat brain.

Although the effects of various cytokines as regulators of hormone synthesis and production are well documented, the role for pituitary hormones as modulators of cytokine synthesis is not fully understood. In this study, we investigated the effect of pituitary hormones' depletion on cytokine synthesis after short- (21 days) and long- (35 days) term hypophysectomy (ST-HX and LT-HX, respectively). The expresssion of the proinflammatory cytokine interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) and the anti-inflammatory cytokines IL-10 and transforming growth factor-beta (TGF-beta) in the rat brain was studied using in situ hybridization. Our results indicate that IL-1beta mRNA-expressing cells were significantly upregulated at day 21 in hypophysectomized rats compared to sham-operated controls. This enhanced expression was also detected later at day 35 post hypophysectomy. However, TNF-alpha mRNA expression was significantly increased only at the later sampling interval. IL-10 mRNA-expressing cells were increased after long-term hypophysectomy compared to controls. TGF-beta mRNA-expressing cells were not increased after hypophysectomy. In conclusion, these results suggest a role for pituitary hormones in IL-1beta, TNF-alpha, and IL-10 synthesis.

Analysis of Variance↗

PubMed1999

A novel mechanism for cytokine regulation: screening, selection, and characterization of anticytokine monoclonal and polyclonal autoantibodies.

We have recently described an immunoregulatory mechanism involving release of neutralizing autoantibodies (Aab) to cytokines during bacterial infections. Intraperitoneal inoculation of Haemophilus influenzae type b (Hib) into Sprague-Dawley rats resulted in high levels of inflammatory mediators early after infection. Increased titers of cytokine Aab were observed, with a peak at day 7. We cloned Aab-producing B cells. Screening of the clones with five different cytokines resulted in detection of Aab-producing clones reactive with each cytokine. After repeated subcloning, monoclonal Aab (mAab) were selected and characterized for their specificity, isotypes, and affinities. To elucidate regulatory importance, mAab to interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) dose-dependently inhibited IFN-gamma-induced MHC expression by peritoneal macrophages and TNF-alpha-induced thymocyte proliferation, respectively. Fab fragments exhibited binding and neutralizing effects, confirming specificities. Cross-reactivity with other rat cytokines was excluded. Pools of clones containing several mAab to each cytokine were obtained and served as polyclonal Aab. The relative affinity of the Aab was determined and found to be of high index. The characterized Aab were tested in methodologic assays for cytokine detection, revealing that some Aab were useful in a cell release capturing (CRC) ELISA.

Animals↗

PubMed1999

A new cell enzyme-linked immunosorbent assay demonstrates gamma interferon suppression by beta interferon in multiple sclerosis.

Multiple sclerosis (MS) is a demyelinating disorder of the central nervous system of unknown etiology. Immune mechanisms involving the proinflammatory cytokine gamma interferon (IFN-gamma) are believed to play an important role in the pathogenesis of MS. IFN-beta-1b has been introduced as a treatment for MS and was found to reduce the number and severity of clinical exacerbations. To examine the influence of IFN-beta-1b on myelin basic protein (MBP)-specific and phytohemagglutinin-induced IFN-gamma production, we developed a cell-released capturing enzyme-linked immunosorbent assay (CRC-ELISA), which rapidly measures spontaneous and antigen- or mitogen-induced cellular IFN-gamma production. CRC-ELISA documented a significant MBP-specific T-cell response in the blood of untreated MS patients, as assessed by IFN-gamma production. This response was suppressed in MS patients treated with IFN-beta-1b. The present work confirms in vivo the in vitro suppressive effects of IFN-beta-1b on IFN-gamma production in MS. Moreover, it provides a powerful new technique for detection of cytokines.

Adult↗

PubMed1999

Induction of neutralizing autoantibodies to interferon-gamma in patients with polyneuropathy.

We previously demonstrated the induction of IFN-gamma in polyneuropathy patients associated with monoclonal gammopathy, but not in patients with presumably non-immunological types of neuropathy. We herein examined mechanism involving release of neutralizing autoantibodies (Aabs) to IFN-gamma in sera from those patients. In contrast to polyneuropathy patients with monoclonal gammopathy, patients with polyneuropathy of presumably non-immunological types showed increased production of neutralizing Aabs specific for IFN-gamma. These results demonstrate a role for autoimmunity in cytokine regulation. However, their association to the clinical manifestations of the disease requires further investigations, which are necessary for future consideration in therapeutic strategies.

Adult↗

PubMed1998

Linomide suppresses chronic-relapsing experimental autoimmune encephalomyelitis in DA rats.

Linomide (quinoline-3-carboxamide) is a synthetic immunomodulator that suppresses several experimental autoimmune diseases. Here we report the effects of Linomide on chronic progressive and/or relapsing experimental autoimmune encephalomyelitis (PR-EAE), a CD4+ T cell mediated animal model of multiple sclerosis (MS). PR-EAE induced in DA rats by inoculation with homogenized guinea pig spinal cord and Freund's complete adjuvant, was strongly suppressed by Linomide administered daily subcutaneously from the day of inoculation. Linomide dose-dependently delayed the interval between immunization and onset of clinical PR-EAE, reduced severity and relapse of clinical PR-EAE, and shortened clinical PR-EAE. These clinical effects were associated with the down-modulation of CNS antigen-induced T cell responses and production of proinflammatory cytokines (IFN-gamma and TNF-alpha) as well as with upregulation of IL-4 (except in spleen MNC), IL-10 and TGF-beta in both spleen MNC and the spinal cord. These effects indicate that Linomide can suppress PR-EAE and may mediate its suppressive effects by regulation of cytokines.

Adjuvants, Immunologic↗

PubMed1998

Recovery from Guillain-Barré syndrome is associated with increased levels of neutralizing autoantibodies to interferon-gamma.

Guillain-Barré syndrome (GBS) is an immune-mediated demyelinating disease of peripheral nerves that is often preceded by an infection and is usually self-restricted. The Th1 cytokine interferon-gamma (IFN-gamma) is thought to be disease-promoting in organ-specific autoimmune diseases. We report the spontaneous induction of IFN-gamma and a mechanism involving the generation of neutralizing autoantibodies (Aabs) to IFN-gamma that may regulate the disease. Numbers of cells spontaneously secreting IFN-gamma in peripheral blood were augmented in GBS, in particular at the peak of clinical disease, and decreased during recovery. This decrease was associated with elevated serum concentrations of IgG Aabs to IFN-gamma. These Aabs specifically bound to IFN-gamma and neutralized its effects in a biological assay. Aabs to IFN-gamma are proposed to be another important regulatory mechanism in IFN-gamma-driven GBS.

Adult↗

PubMed1998

Effect of triclosan on interleukin-1 beta production in human gingival fibroblasts challenged with tumor necrosis factor alpha.

The effect of the dentifrice ingredient triclosan (2,4,4'-trichloro-2'-hydroxyldiphenyl ether) on the production of interleukin (IL)-1beta and IL-6 was studied in human gingival fibroblasts challenged with tumor necrosis factor alpha (TNFalpha) in vitro. When gingival fibroblasts were treated simultaneously with triclosan (0.25, 0.5 microg/ml) and TNFalpha (10 ng/ml), the stimulatory effect of TNFalpha on IL-1beta production was reduced by the agent. In situ hybridisation showed that the TNFalpha-induced expression of IL-1beta mRNA was significantly reduced by triclosan. Furthermore, when the cells were treated simultaneously with a known protein kinase C (PKC) activator, phorbol 12-myristate-13-acetate (PMA) and TNFalpha in the presence of triclosan (0.5 microg/ml), the agent reduced the production of IL-1beta. In contrast to its effect on IL-1beta, triclosan did not influence the mRNA expression or the production of IL-6 induced by TNFalpha. The finding that triclosan reduces the production of the inflammatory mediator IL-1beta in gingival fibroblasts further supports the view that triclosan exhibits an anti-inflammatory effect.

Anti-Infective Agents, Local↗

PubMed1998

Induction of cytokines and anti-cytokine autoantibodies in cerebrospinal fluid (CSF) during experimental bacterial meningitis.

We have recently described the induction of anti-cytokine autoantibodies (Aabs) in the serum as a novel mechanism for cytokine regulation during bacterial infections. Here we use the infant rat-model of Haemophilus influenzae type b (Hib) meningitis to examine the induction of five potentially important cytokines and their autoantibody responses in the CSF. Protein levels of the cytokines interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta), IL-4 and IL-10 were detected at day 3 post-inoculation (p.i.) with maximum induction at day 8. Thereafter, these levels of cytokines had become undetectable. Increased Aab titres to these cytokines, except IL-4, were registered with peak levels between days 7 and 9. Upon re-inoculation with Hib at day 30, regeneration of Aabs was recorded 7 days later (i.e. at day 37). To control the specificity of these Aabs, preincubation of the CSF with a cytokine inhibited the binding effects of that particular cytokine, but not those of any other cytokine. Aabs dose-dependently inhibited IFN-gamma-induced MHC expression by peritoneal macrophages and TNF-alpha-mediated L929 cytotoxicity. Our data demonstrate for the first time the existence of the anti-cytokine antibodies in the CSF of the meningitis Hib model. Furthermore, the data present a role for the Aabs in cytokine regulation, which is consistent with the previously demonstrated effects of the Aabs in the serum.

Animals↗

PubMed1998

Cytokine autoantibodies in multiple sclerosis, aseptic meningitis and stroke.

BACKGROUND: We have recently described the induction of anti-cytokine autoantibodies during bacterial infections and autoimmune diseases as a mechanism for cytokine regulation. METHODS: Herein, we study the occurrence of autoantibodies to pro- and anti-inflammatory cytokines in cerebrospinal fluid and plasma from patients with multiple sclerosis, aseptic meningitis and stroke. RESULTS: Increased levels of autoantibodies to interferon gamma, tumour necrosis factor alpha, interleukin 4 and interleukin 10 were detected in both compartments of multiple sclerosis and aseptic meningitis patients. Interestingly, in cerebrospinal fluid from stroke patients, only autoantibodies to interleukin 4 and interleukin 10, but not interferon alpha or tumour necrosis factor alpha were detected. No significant autoantibody levels were registered in plasma from stroke patients against all four cytokines compared with healthy control subjects. The latter revealed very low autoantibody levels in plasma and no detectable autoantibodies in cerebrospinal fluid. CONCLUSIONS: Our data show for the first time the occurrence of cytokine autoantibodies in these diseases, but their biological significance is unclear.

Adult↗

PubMed1998

Inhibition of experimental autoimmune encephalomyelitis in Lewis rats by nasal administration of encephalitogenic MBP peptides: synergistic effects of MBP 68-86 and 87-99.

Induction of mucosal tolerance by inhalation of soluble peptides with defined T cell epitopes is receiving much attention as a means of specifically down-regulating pathogenic T cell reactivities in autoimmune and allergic disorders. Experimental autoimmune encephalomyelitis (EAE) induced in the Lewis rat by immunization with myelin basic protein (MBP) and Freund's adjuvant (CFA) is mediated by CD4+ T cells specific for the MBP amino acid sequences 68-86 and 87-99. To further define the principles of nasal tolerance induction, we generated three different MBP peptides (MBP 68-86, 87-99 and the non-encephalitogenic peptide 110-128), and evaluated whether their nasal administration on day -11, -10, -9, -8 and -7 prior to immunization with guinea pig MBP (gp-MBP) + CFA confers protection to Lewis rat EAE. Protection was achieved with the encephalitogenic peptides MBP 68-86 and 87-99, MBP 68-86 being more potent, but not with MBP 110-128. Neither MBP 68-86 nor 87-99 at doses used conferred complete protection to gp-MBP-induced EAE. In contrast, nasal administration of a mixture of MBP 68-86 and 87-99 completely blocked gp-MBP-induced EAE even at lower dosage compared to that being used for individual peptides. Rats tolerized with MBP 68-86 + 87-99 nasally showed decreased T cell responses to MBP reflected by lymphocyte proliferation and IFN-gamma ELISPOT assays. Rats tolerized with MBP 68-86 + 87-99 also had abrogated MBP-reactive IFN-gamma and tumor necrosis factor-alpha mRNA expression in lymph node cells compared to rats receiving MBP 110-128 nasally, while similar low levels of MBP-reactive transforming growth factor-beta and IL-4 mRNA expressing cells were observed in the two groups. Nasal administration of MBP 68-86 + 87-99 only slightly inhibited guinea pig spinal cord homogenate-induced EAE, and passive transfer of spleen mononuclear cells from MBP 68-86 + 87-99-tolerized rats did not protect naïve rats from EAE. Finally, we show that nasal administration of MBP 68-86 + 87-99 can reverse ongoing EAE induced with gp-MBP, although higher doses are required compared to the dosage needed for prevention. In conclusion, nasal administration of encephalitogenic MBP peptides can induce antigen-specific T cell tolerance and confer incomplete protection to gp-MBP-induced EAE, and MBP 68-86 and 87-99 have synergistic effects. Non-regulatory mechanisms are proposed to be responsible for tolerance development after nasal peptide administration.

Administration, Intranasal↗

PubMed1998

Mutations in the promoter of adenylyl cyclase (AC)-III gene, overexpression of AC-III mRNA, and enhanced cAMP generation in islets from the spontaneously diabetic GK rat model of type 2 diabetes.

Glucose-induced insulin release is decreased in the spontaneously diabetic GK rat, a nonobese rodent model of type 2 diabetes. Forskolin restores the impaired insulin release in both the isolated perfused pancreas and isolated islets from these rats (Abdel-Halim et al., Diabetes 45:934-940, 1996). We demonstrate here that the insulinotropic effect of forskolin in the GK rat is due to increased generation of cAMP and that it is associated with overexpression of adenylyl cyclase (AC)-III mRNA and gene mutations. The AC-III mRNA overexpression was demonstrated by in situ hybridization using oligonucleotide probes binding to different regions of the rat AC-III mRNA. It was associated with the presence of two point mutations identified at positions -28 bp (A --> G) and -358 bp (A --> C) of the promoter region of the AC-III gene and was demonstrable in both GK rat islets and peripheral blood cells. Transfection of COS cells with a luciferase reporter gene system revealed up to 25-fold increased promoter activity of GK AC-III promoter when compared with normal rat promoter (P < 0.0001). In conclusion, forskolin restores the impaired insulin release in islets of the GK rat through enhanced cAMP generation. This is linked to overexpression of AC-III mRNA in GK islets due to two functional point mutations in the promoter region of the AC-III gene.

Adenylyl Cyclases↗

PubMed1998

Interactions between human embryonic forebrain cells and the cytokines interferon-gamma and interleukin-4.

In the present study we investigated the capacity of human first trimester forebrain cells at different gestational ages to produce IFN-gamma and IL-4. We also studied the effects of IFN-gamma on their proliferation, survival and expression of MHC antigens. IFN-gamma but not IL-4 was spontaneously produced after 24 h cultures. Furthermore, IFN-gamma exhibited anti-proliferative effects and induced MHC expression on these cells. However, the IFN-gamma exposed cultures showed significantly higher cell survival compared to un-exposed cultures. Co-culture with IL-4 blocked the IFN-gamma production and reversed its anti-proliferative effects. These interactions suggest important roles for cytokines in the survival, proliferation and differentiation of human embryonic and fetal forebrain cells.

Cell Division↗

PubMed1998

Cytokines and anti-cytokine autoantibodies during experimental african trypanosomiasis in mice with disrupted interferon-gamma and interferon-gamma receptor genes.

We studied cytokines and anti-cytokine autoantibodies (Aabs) during T.b.brucei infections in IFN-gamma-/-, IFN-gammaR-/- and wild-type mice. Increased serum levels of IFN-gamma, TNF-gamma and IL-4 with decreased Aabs to these cytokines were recorded early during infections in all mice (except IFN-gamma in IFN-gamma-/- mice). Later, these responses were reversed, and surprisingly Aabs reacting to IFN-gamma in the IFN-gamma -/- mice were detected. To examine the possibility that an IFN-ç immunoreactive molecule might be expressed due to infections and upon gene deletion, anti-IFN-gamma antibody was inoculated and resulted in abrogation of such Aabs. The scenario was different for IL-10 and TGF- since IFN-gammaR-/- and wild-type mice showed low cytokines and high Aabs early during infections, but later high cytokines and low Aabs were registered. Interestingly, IFN-gamma-/- mice exhibited reversed levels of both IL-10 and TGF-beta, and also of their Aabs. Fab fragments of purified serum immunoglobulins showed binding and neutralizing effects in biological assays. Pre-absorption of the Fab fragments with a cytokine inhibited the binding and neutralization effects of this cytokine, but not of other cytokines. These results highlight an important role for autoimmunity in cytokine regulation, and that genomic deletion of IFN-gamma modulates cytokines and their Aab responses in experimental African trypanosomiasis.

Animals↗

PubMed1997

Expression of MHC class II CD4+ and ED1 molecules in association with selective hippocampal neuronal degeneration after long-term adrenalectomy.

The neuroendocrine and the immune systems are interconnected. Monoclonal antibodies against major histocompatibility complex (MHC) class I, class II, CD4, CD8, pan T cells, and macrophages were used for immunostaining brains from adrenalectomized (ADX) and shamoperated rats to investigate the potential involvement of the immune/inflammatory mechanisms in the neurodegeneration of hippocampus after ADX. Our results demonstrate upregulation of MHC class II, CD4 antigens and activated microglial marker-ED1 expression selectively in the hippocampus after ADX. The absence of CD5 reactivity precludes that these activated cells were T lymphocytes. The activated microglial cells may either be instrumental in the hippocampal neuronal loss or activated secondarily to the neuronal degeneration after long-term adrenalectomy.

Adrenalectomy↗

PubMed1997

Major histocompatibility complex-controlled protective influences on experimental autoimmune encephalomyelitis are peptide specific.

The myelin basic protein (MBP) peptide 63-88-induced experimental autoimmune encephalomyelitis (EAE) and its associated T cell cytokine profile are influenced by the rat major histocompatibility complex (MHC). There is an allele-specific protective influence of the MHC class I region, whereas the MHC class II region display either disease-protective or -promoting effects. To investigate if the MHC-associated protection is dependent on certain combinations of MBP peptide and MHC molecules, we have now used another peptide (MBP 89-101). A broader and different set of rat MHC alleles were associated with EAE induced with MBP 89-101 as compared to MBP 63-88. All EAE-susceptible strains mounted peptide-specific strong T helper (Th) 1-like immune responses in vitro. Immunization of rats with an extended peptide (MBP 87-110) induced EAE associated with the same MHC haplotypes as the 89-101 peptide, except in LEW.1N (RT1 pi) rats which were relatively resistant. Only this strain responded with additional Th2-like and transforming growth factor-beta responses to the peptide in vitro. In vivo depletion of CD8+ cells aggravated the disease in this strain. We conclude that both MHC-controlled promoting and protective influences on EAE are dependent on certain MHC/MBP peptide combinations, and that the 87-110 region of MBP contains a major MHC-associated encephalitogenic epitope in the rat.

Alleles↗

PubMed1997

Growth hormone stimulates production of interferon-gamma by human peripheral mononuclear cells.

There is substantial evidence for interactions between the immune and endocrine systems at different levels. In the present study we investigated whether human growth hormone (hGH) could stimulate proliferation of interferon-gamma-secreting cells (IFN-gamma-SC), and production of IFN-gamma. Human peripheral blood mononuclear cells (PBMC) taken from 15 normal subjects were incubated with varying doses (200,400,600 and 800 ng/ml) of recombinant hGH. Samples of cells were also incubated with PBS buffer (without hGH) to serve as controls. Effects of hGH were studied by enumerating IFN-gamma-SC and by measuring the concentration of IFN-gamma using an Immunospot assay and an enzyme-linked immunosorbent assay, respectively. The results showed that hGH significantly increased both the number of IFN-gamma-SC and the concentration of IFN-gamma in a dose-dependent manner. The maximum effects were obtained in the presence of (400 ng/ml) hGH (15 +/- .5 IFN-gamma-SC/10(6) PBMC and 300 +/- 55 U/ml IFN-gamma) compared to controls (4 +/- 2 IFN-gamma-SC/10(6) PBMC and 50 +/- 10 U/ml IFN-gamma). The results of the present study suggest that hGH might influence the immune system by stimulating the proliferation of IFN-gamma-SC and the production of IFN-gamma.

Human Growth Hormone↗