Transforming growth factor-β1 suppresses autoantigen-induced expression of pro-inflammatory cytokines but not of interleukin-10 in multiple sclerosis and myasthenia gravis

Multiple sclerosis (MS) is associated with high levels of circulating T lymphocytes that respond to the myelin antigens myelin basic protein (MBP) and proteolipid protein (PLP) by producing various cytokines including interferon-γ (IFN-γ) that makes MS worse and transforming growth factor-β (TGF-β), an endogenously produced immunosuppressant that might act beneficially. To further define the role of TGF-β in MS, we examined the effects of recombinant TGF-β1 (rTGF-β1) on autoantigen-mediated regulation of cytokines in MS and myasthenia gravis (MG). Blood mononuclear cells (MNC) were cultivated with or without rTGF-β1, and with or without autoantigen or the recall antigen PPD. MNC expressing cytokine mRNA were detected after in situ hybridization with radiolabeled cDNA oligonucleotide probes. Femtogram concentrations of rTGF-β1 suppressed MBP-, PLP- and PPD-induced upregulation of IFN-γ, IL-4, IL-6, tumor necrosis factor-α (TNF-α), TNF-α and perforin in MS, and acetylcholine receptor (AChR)-induced augmentation of these pro-inflammatory cytokines in MG, but had no effects on autoantigen- or PPD-induced expression of IL-10 or TGF-β itself. rTGF-β1 also suppressed numbers of myelin antigen-reactive IFN-γ- and IL-4-secreting cells in MS and AChR-reactive IFN-γ and IL-4 secreting cells in MG. The selective suppressive effects of TGF-β1 on autoantigen-induced upregulation of pro-inflammatory cytokines makes TGF-β1 attractive as a treatment alternative in MS and MG.     

Multiple sclerosis: myelin basic protein induced mRNA expression of proinflammatory cytokines in mononuclear cells is suppressed by interferon-β 1b in vitro

Beta-interferon (IFN-β) is a promising treatment in multiple sclerosis (MS), reducing the exacerbation rate and MRI lesion burden, as well as the disease progression in relapsing-remitting MS. IFN-β was originally defined by its antiviral effects, but the interest has recently been focused on its immunomodulatory properties. Myelin basic protein (MBP) is one of several autoantigens considered to be the target for autoaggressive immune responses, which eventually might lead to the development of MS. To study in-vitro effects of IFN-β1b on MBP induced cytokine expression, mRNA for the Th1 cytokines IFN-γ and TNF-α, the Th2 related IL-4 and IL-6, the cytolytic perforin and the immune response downregulating TGF-β was measured with in situ hybridization after culture of blood mononuclear cells (MNC) in the presence and absence of MBP. Numbers of cells expressing IFN-γ, TNF-α, perforin and IL-4 mRNA were significantly suppressed after culture with 10 U/ml IFN-β1b. No such effect was seen on MBP induced IL-6 or TGF-β mRNA expression. These observations suggest that one of the major effects of IFN-β1b is the induction of a shift in the cytokine mRNA profile towards a more immunosuppressive pattern. In parallel in vitro tests, the control substance dexametasone (40 μg/ml) reduced the numbers of cells expressing mRNA for all cytokines under study with the exception of TGF-β, to an extent equal to or even more pronounced than IFN-β1b.     

In vitro TNF-α, IL-2 and IFN-γ production as markers of relapses in multiple sclerosis

In 22 patients with definite multiple sclerosis (MS) we determined with monthly intervals over a period of 24 months the in vitro tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and interleukin-2 (IL-2) production and the serum neopterin levels. The results were compared with normative data collected from 14 healthy controls over the same period. Twenty-nine relapses in 13 patients were noticed. We found increased in vitro TNF-α production from 4 weeks on prior to the day of an exacerbation. There was a significant correlation with in vitro IFN-γ release, the absolute blood monocyte count and the serum neopterin levels, suggesting that monocytes stimulated by IFN-γ play an important role in the TNF-α production. Serial analysis of in vitro TNF-α production proved to be a helpful tool in predicting relapses in MS patients. Furthermore, elevated levels of IFN-γ and IL-2 after stimulation with OKT3 during exacerbations were demonstrated. Serial analysis of these two biological markers revealed to be of no value in predicting relapses.     

Amelioration of flulike symptoms at the onset of interferon β- 1b therapy in multiple sclerosis by low-dose oral steroids is related to a decrease in interleukin-6 induction

Low-dose oral steroid use at the onset of interferon β-1b (IFNβ-1b) therapy in relapsing-remitting multiple sclerosis (RR-MS) patients reduces flulike symptoms. To determine the mechanism by which steroid treatment minimizes these side effects, we analyzed the percentage of interleukin-6 (IL-6)–, interferon-γ (IFN-γ)-, tumor necrosis factor α (TNF-α)–, and IL-10–producing cells before and after 3 months of IFNβ-1b therapy onset. Our results support a relationship between IL-6 induction and fever. Such side effects can be ameliorated by steroids.     

Genetic control of multiple sclerosis: Increased production of lymphotoxin and tumor necrosis factor-α by HLA-DR2+ T cells

Lymphotoxin (LT) and tumor necrosis factor-α (TNF-α) play an important role in the pathogenesis of multiple sclerosis (MS). MS is associated with the HLA-DR2, Dw2, DQ6 HLA class II haplotype. Because both LT and TNF-α are encoded in the HLA region, the HLA association of MS may be related to the production of these cytokines. To test this hypothesis, we investigated the production of LT, TNF-α, and interferon-γ (IFN-γ) by CD4⁺ T-cell lines (TCLs) specific for myelin basic protein (MBP) or tetanus toxoid (TT) isolated from MS patients and normal controls. After stimulation with specific antigen but not mitogen, TCLs from HLA-DR2⁺ donors produced significantly more LT and TNF-α, than TCLs from DR2^? donors. In contrast, HLA-DR2⁺ and DR2^? TCLs did not differ in the production of IFN-γ, a cytokine also produced by T cells but not encoded in the HLA region. Increased secretion of LT and TNF-α was unrelated to the specificity (MBP vs TT), MHC restriction (HLA-DR2 vs other DR molecules), or source (MS vs normal) of the TCLs. There was no significant association of the cytokine production with individual LT or TNF-α alleles, indicating that the increased production of these cytokines may be linked to other polymorphic genes in this region. The results suggest that the association of MS with HLA-DR2 implies a genetically determined propensity of T cells to produce increased amounts of LT and TNF-α.     

Interferon-γ secretion by peripheral blood T-cell subsets in multiple sclerosis: Correlation with disease phase and interferon-β therapy

Interferon-γ (IFN-γ) is implicated as a participant in the immune effector and regulatory mechanisms considered to mediate the pathogenesis of multiple sclerosis (MS). We have used an intracellular cytokine staining technique to demonstrate that the proportion of ex vivo peripheral blood CD4 and CD8 T-cell subsets expressing IFN-γ is increased in secondary progressing (SP) MS patients, whereas the values in untreated relapsing-remitting (RR) MS patients are reduced compared with those of controls. Patients treated with interferon-β (IFN-β) have an even more significant reduction in the percentage of IFN-γ–secreting cells. The finding that the number of IFN-γ–expressing CD8 cells is increased in SPMS patients, a group with reduced functional suppressor activity, and is most significantly reduced by IFN-β therapy, which increases suppressor activity, indicates that IFN-γ secretion by CD8 T cells and functional suppressor defects attributed to this cell subset in MS can be dissociated. Ann Neurol 1999;45:247–250     

Cytokine production in the central nervous system of Lewis rats with experimental autoimmune encephalomyelitis: dynamics of mRNA expression for interleukin-10, interleukin-12, cytolysin,tumor necrosis factor α and tumor necrosis factor β

The kinetics of mRNA expression in the central nervous system (CNS) for a series of putatively disease-promoting and disease-limiting cytokines during the course of experimental autoimmune encephalomyelitis (EAE) in Lewis rats were studied. Cytokine mRNA-expressing cells were detected in cryosections of spinal cords using in situ hybridization technique with synthetic oligonucleotide probes. Three stages of cytokine mRNA expression could be distinguished: (i) interleukin (IL)-12, tumor necrosis factor (TNF)-β (=lymphotoxin-α) and cytolysin appeared early and before onset of clinical signs of EAE; (ii) TNF-α peaked at height of clinical signs of EAE; (iii) IL-10 appeared increasingly at and after clinical recovery. The early expression of IL-12 prior to the expression of interferon-γ (IFN-γ) mRNA shown previously is consistent with a role of IL-12 in promoting proliferation and activation of T helper 1 (Th1) type cells producing IFN-γ. The TNF-β mRNA expression prior to onset of clinical signs favours a role for this cytokine in disease initiation. A pathogenic effector role of TNF-α was suggested from these observations that TNF-α mRNA expression roughly paralleled the clinical signs of EAE. This may be the case also for cytolysin. IL-10-expressing cells gradually increased to high levels in the recovery phase of EAE, consistent with a function in down-regulating the CNS inflammation. From these data we conclude that there is an ordered appearance of putative disease-promoting and -limiting cytokines in the CNS during acute monophasic EAE.     

Interferon-β but not Glatiramer acetate stimulates CXCL10 secretion in primary cultures of thyrocytes: a clue for understanding the different risks of thyroid dysfunctions in patients with multiple sclerosis treated with either of the two drugs

Autoimmune thyroid disease (AITD) has been reported in patients with multiple sclerosis (MS) receiving interferon-beta (IFN-β), but not in those receiving Glatiramer acetate (GA). CXCL10 is a chemokine playing a pathogenetic role in AITD and MS. Our aim was to evaluate the effects on CXCL10 secretion of IFN-β and GA, alone and in combination with TNF-α, in primary cultures of thyrocytes (PCT). Significant and dose-dependent secretions of CXCL10 were induced by IFN-β but not GA. TNF-α synergistically increased IFN-β induced CXCL10 secretion. These results may provide an explanation for the occurrence of AITD during IFN-β, but not during GA, treatment for MS.     

Interleukin 1-β- and tumor necrosis factor-α-mediated regulation of ICAM-1 gene expression in astrocytes requires protein kinase C activity

Several adhesion molecules including intracellular adhesion molecule-1 (ICAM-1) are expressed by astrocytes, the predominant glial cell of the central nervous system (CNS). Such molecules are important in the trafficking of leukocytes to sites of inflammation, and in lymphocyte activation. ICAM-1 is constitutively expressed by neonatal rat astrocytes, and expression is enhanced by the proinflammatory cytokines interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ), with IL-1β and TNF-α being the strongest inducers. In this study, we have examined the nature of the second messengers involved in ICAM-1 gene expression induced by the cytokines IL-1β and TNF-α. Our results indicate that stimuli related to protein kinase C (PKC) such as the phorbol ester phorbol 12-myristate 13-acetate (PMA) and calcium ionophore A23187 increase ICAM-1 mRNA expression, whereas cyclic nucleotide analogs and PKA agonists have no effect. Pharmacologic inhibitors of PKC such as H7, H8, and calphostin C inhibit ICAM-1 gene expression inducible by IL-1β and TNF-α. Prolonged treatment of astrocytes with PMA results in a time-dependent downregulating of the PKC isoforms α, δ, and ?, and a concomitant diminution of ICAM-1 mRNA expression induced by IL-1β, TNF-α, and PMA itself at specific time points post-PMA treatment. These data, collectively, demonstrate a role for various PKC isoforms in IL-1β and TNF-α enhancement of ICAM-1 gene expression in rat astrocytes. © 1995 Wiley-Liss, Inc.     

Increased transforming growth factor-β, interleukin-4, and interferon-γ in multiple sclerosis

The inflammatory nature of multiple sclerosis (MS) implicates the participation of immunoregulatory cytokines, including the T-helper type 1 (Th1) cell–associated interferon-σ (IFN-σ), the Th2 cell–related interleukin-4 (IL-4), and the immune response–downregulating cytokine transforming growth factor-β (TGF-β), but proof for their involvement in MS has been lacking. By adopting in situ hybridization with complementary DNA oligonucleotide probes for human IFN- IL-4, and TGF-β, the expression of mRNA for these cytokines was detected in mononuclear cells (MNC) from blood and cerebrospinal fluids. Strongly elevated levels of MNC expressing all three cytokines were found in peripheral blood and at even higher frequencies in cerebrospinal fluid from untreated patients with MS and optic neuritis, i.e., a common first manifestation of MS, compared with patients with other neurological diseases and healthy subjects. In MS and optic neuritis, IL-4 mRNA expressing cells predominated, followed by TGF-β– and IFN-σ–positive cells. Control patients with myasthenia gravis had similarly elevated levels of IFN-σ and TGF-β mRNA expressing blood MNC but lower numbers of IL-4–positive cells. No or slight disability of MS was associated with high levels of TGF-β mRNA expressing cells, while MS patients with moderate or severe disability had high levels of IFN-σ–positive cells. IFN-σ and TGF-β may have opposing effects in MS, and treatments inhibiting IFN-σ and/or promoting TGF-β might ameliorate MS.     

Selective inhibition of human glial inducible nitric oxide synthase by interferon-β: Implications for multiple sclerosis

Nitric oxide generated from the inducible nitric oxide synthase (iNOS) has been implicated in the pathogenesis of multiple sclerosis. Because significant species- and cell-specific differences exist in the expression of iNOS, we used primary human glial cell cultures to screen for an inhibitor of iNOS expression. Remarkably, among numerous soluble factors tested, interferon-β (IFN-β) alone showed a selective and potent inhibition of interleukin-1β/interferon-γ (IL-1β/IFN-)–induced iNOS expression in astrocytes. Inhibition of iNOS may provide a mechanism by which IFN-β can ameliorate inflammation and cytotoxicity in the central nervous system of patients with multiple sclerosis.     

Resistance and susceptibility to experimental autoimmune neuritis in Sprague-Dawley and Lewis rats correlate with different levels of autoreactive T and B cell responses to myelin antigens

Experimental autoimmune neuritis (EAN) is a CD4⁺ T cell-mediated, inflammatory demyelinating disease of the peripheral nervous system (PNS) that serves as a model for Guillain-Barré syndrome (GBS) in humans. Various mouse and rat strains show different susceptibilities to EAN that can be induced by immunization with bovine PNS myelin (BPM) + Freund's complete adjuvant (FCA). We examined PNS-induced T and B cell responses and cytokine protein production as well as mRNA expression to study the mechanisms behind susceptibility to EAN in Lewis rats and resistance in Sprague-Dawley (SD) rats. Lewis rats with EAN have elevated PNS myelin-reactive interferon-γ (IFN-γ) production, TNF-α mRNA expression, and increased B cell responses to PNS myelin antigens, but low PNS myelin-reactive transforming growth factor-β (TGF-β) and interleukin (IL)-10 mRNA expression in lymph node mononuclear cells (MNC). In contrast, resistance to EAN in SD rats is associated with reduced BPM and P2 peptide-reactive IFN-γ production, TNF-α mRNA expression, and suppressed B cell responses to PNS myelin antigens as well as up-regulation of TGF-β and IL-10 mRNA expression. Resistance to EAN is also associated with low-grade inflammation or absence of histological evidence of EAN. These results suggest that differential autoreactive T and B cells responses to PNS myelin antigens are strain specific, and the susceptibility to EAN is related to quantitative rather than qualitative differences in distribution between pro-inflammatory and anti-inflammatory cytokines. J. Neurosci. Res. 54:373–381, 1998. © 1998 Wiley-Liss, Inc.     

Review: cytokines and the pathogenesis of multiple sclerosis

Perivascular accumulation of mononuclear cells (MNCs) in the central nervous system (CNS) and high levels of myelin autoantigen-reactive T cells in blood and further enriched in cerebrospinal fluid (CSF) are characteristic for multiple sclerosis (MS) and suggest a role for immunoregulatory cytokines in MS pathogenesis. The difficulties inherent to measurements of cytokine concentrations in body fluids have been partly overcome by adopting techniques allowing cytokine determinations on cellular level. MS is associated with the parallel up-regulation of proinflammatory [interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), lymphotoxin-α, and interleukin (IL)-12] and immune response-down-regulating [transforming growth factor-β (TGF-β), IL-10] cytokines systemically. A preferential up-modulation of TNF-α and lymphotoxin-α is observed in clinical exacerbations and of TGF-β and IL-10 in remissions. The B cell-stimulating IL-4 and IL-6 are also up-regulated in MS, as is the cytolysis-promoting perforin. Cytokine production is elevated to an even higher degree in the CSF than systemically, underlining the autonomy of the immune responses in the CSF. All cytokine abnormalities are demonstrable already in very early MS, manifested by acute unilateral optic neuritis associated with more than two MS-like lesions on brain magnetic resonance imaging and oligoclonal IgG bands in CSF. The cytokine abnormalities hitherto observed are not MS specific, because they can be found in other inflammatory CNS diseases, e.g., aseptic meningitis and even noninflammatory neurological diseases like stroke. The influence on cytokine profiles, e.g., suppressing proinflammatory cytokines and promoting TGF-β and IL-10, could be an important way to identify new and promising treatments of MS. © 1996 Wiley-Liss, Inc.     

脑梗死患者血浆同型半胱氨酸浓度与血清TNF-α、IFN-γ水平的相关性临床研究

目的探讨脑梗死患者血浆同型半胱氨酸（Hcy）浓度与血清肿瘤坏死因子-α（TNF-α）、干扰素-γ（IFN-γ）水平的变化的关系及意义。方法选择脑梗死患者60例,健康体检者60例（对照组）,采用高效液相色谱荧光法检测脑梗死组及对照组血浆Hcy水平,采用酶联免疫吸附测定法（ELlSA法）检测血清TNF-α、IFN-γ浓度。结果脑梗死组Hcy、TNF-α、IFN-γ水平均明显高于对照组,差异有统计学意义（P〈0.05）;脑梗死组血浆Hcy浓度与血清TNF-α（r=0.716,P〈0.001）、IFN-γ（r=0.683,P〈0.001）水平呈正相关。结论脑梗死患者血清TNF-α、IFN-γ水平显著升高,且与Hcy浓度明显相关。     

Methylprednisolone attenuates interferon-β induced expression of HLA-DR on monocytes

The effect of methylprednisolone on constitutive and interferon-β(IFN-β) induced HLA-DR expression on monocytes from multiple sclerosis (MS) patients was investigated. Constitutive HLA-DR expression was reduced by 50% following a single dose(500 mg) of intravenous methylprednisolone (IVMP). Stimulation with natural IFN-β, in vitro, resulted in a 20 fold increase in HLA-DR expression. Following IVMP, IFN-β inducible HLA-DR levels were reduced (non-significantly) by 20–30%. Experiments in which monocytes from normal subjects and MS patients were pre-treated in vitro with methylprednisolone prior to IFN-β stimulation revealed that induction of HLA-DR was significantly inhibited; in contrast, IFN-β induced HLA-DR expression was not down-regulated following subsequent in vitro treatment with methylprednisolone. These findings suggest that the immunomodulatory effects of IVMP could be attenuated in MS patients receiving regular IFN-β therapy.