Exacerbations of multiple sclerosis in patients treated with gamma interferon

Expression of interferon-gamma in the lens exacerbates anterior uveitis and induces retinal degenerative changes in transgenic Lewis rats

Interferon-gamma (IFN-gamma) is a pleiotropic cytokine that has been implicated in immunopathogenic mechanisms of a number of inflammatory diseases of autoimmune or infectious disease etiology. However, its exact role is still a matter of debate. In experimental mouse models, IFN-gamma has been shown to exacerbate autoimmune thyroiditis, insulin-dependent diabetes mellitus, and autoimmune neuritis while it confers protection against experimental allergic encephalomyelitis and experimental uveitis. In this study, we generated transgenic rats with constitutive expression of IFN-gamma in the eye to study its paracrine effects and to investigate whether local production of IFN-gamma also confers protection against uveitis in the rat species. We show here that chronic exposure of ocular cells to IFN-gamma results in apoptotic death of retinal ganglion cells, development of chronic choroiditis, formation of retinal in-foldings, and activation of proinflammatory genes. In contrast to its protective systemic effect in the mouse, constitutive secretion of IFN-gamma in the rat eye was found to predispose the development of severe anterior uveitis and induction of retinal degenerative processes that impair visual acuity. Our data underscore the danger in extrapolation of cytokine effects in the mouse to humans without corroborating evidence in other species.

Th1 and Th2 T helper cell subsets affect patterns of injury and outcomes in glomerulonephritis

The recognition that human immune responses can be directed by two different subsets of T helper cells (Th1 and Th2) has been an important development in modern immunology. Immune responses polarized by either the Th1 or Th2 subset predominance result in different inflammatory effector pathways and disease outcomes. Many autoimmune diseases are associated with either Th1- or Th2- polarized immune responses. Although these different immune response patterns are relevant to glomerulonephritis (GN), little attention has been paid to the consequences of Th1 or Th2 predominance of nephritogenic immune responses for the pattern and outcome of GN. Unlike other autoimmune conditions, GN results from a variety of different immune responses and has a range of histologic features and immune effectors in glomeruli. This review assesses the data available from studies of experimental and human GN that address the Th1 or Th2 predominance of nephritogenic immune responses and their relevance to the different histopathological patterns and outcomes of GN. In particular, the evidence that Th1-predominant nephritogenic immune responses are associated with severe proliferative and crescentic GN is presented.

Herpesviruses--a rationale for antiviral treatment in multiple sclerosis

In multiple sclerosis (MS), the extensive and long lasting search for viruses or other pathogens has hitherto failed to identify a common etiological agent. However, the beneficial effects by interferon-beta treatment in MS, although suggested to depend mainly on immunomodulation, might lend support to a viral involvement in the pathogenesis. The human herpesviruses have attracted interest since their recurrent modes of infection share some similarity with the relapsing-remitting course of MS, most members are readily detected within the brain, and several of these viruses may induce demyelination within the central nervous system in human hosts as well as in animal models. Accumulated diagnostic and epidemiological data are compatible with a role for the herpesviruses as possible cofactors rather than etiological agents, and recent studies showing early neuronal damage in MS patients focus attention on the neurotropic alpha-herpesviruses. Antiviral treatment trials with safe and effective drugs such as valaciclovir offer a possibility of testing the hypotheses concerning herpesviral involvement in MS.

Interferon-gamma reduces cyclooxygenase-2-mediated prostaglandin E2 production from primary mouse astrocytes independent of nitric oxide formation

Nitric oxide (NO) and prostaglandins (PGs) modulate inflammatory and immune responses in the central nervous system (CNS). Both NO and PG synthesis have been described in appropriately stimulated astrocytes. In other systems, both positive and negative modulation of cyclooxygenase (COX) activity, hence PG synthesis, have been described by NO. Since interferon (IFN)-gamma is known to upregulate the production of NO from astrocytes, the present study was designed to investigate the effect of IFNgamma on PG production from activated astrocytes and to determine whether this effect is mediated by NO. Astrocytic PG production was induced by exposure of murine cortical cultures to lipopolysaccharide (LPS). This induction was time- and concentration-dependent, and prevented by inhibitors of transcription and translation, as well as the selective COX-2 inhibitor, NS-398. LPS-induced expression of COX-2 mRNA and protein was confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis, respectively. Exposure of LPS-treated astrocytes to IFNgamma resulted in a concentration-dependent decrease in PGE2 accumulation which was accompanied by a striking parallel increase in NO formation. However, the NOS inhibitors, N(G)-nitro-L-arginine or N6-(1-iminoethyl)-lysine, failed to reverse the IFNgamma-mediated diminution of LPS-induced PGE2 production, indicating that the IFN-gamma-mediated reduction in COX-2-dependent PGE2 production occurred independent of NO formation. Additional experiments demonstrated that IFN-gamma acted mainly by downregulating the expression of COX-2 protein. Present results indicate that PG and NO synthesis in mouse cortical astrocytes in vitro are under the direct reciprocal control of IFNgamma.

Amelioration of collagen-induced arthritis and suppression of interferon-gamma, interleukin-12, and tumor necrosis factor alpha production by interferon-beta gene therapy

OBJECTIVE

To investigate the therapeutic effects and possible mechanisms of action of constitutive expression of interferon-beta (IFNbeta) by syngeneic fibroblasts from DBA/1 mice in the collagen-induced arthritis (CIA) model.

METHODS

Immortalized embryonic DBA/1 fibroblasts were infected with a retrovirus expressing murine IFNbeta. IFNbeta-expressing fibroblasts were then implanted intraperitoneally into mice immunized with bovine type II collagen. The effect of IFNbeta on paw swelling, anticollagen antibody levels, IgG1/IgG2a isotype profiles, arthritis score, histologic joint damage, and cytokine secretion from lymph node cells and from bone marrow-derived macrophages was assessed.

RESULTS

A single injection of IFNbeta-secreting fibroblasts was sufficient to prevent arthritis or to ameliorate existing disease. Thus, IFNbeta reduced the clinical score and paw swelling irrespective of whether the injection was administered before or after disease onset in treated mice, compared with that in the untreated control group (P < 0.05). Histologic findings in the IFNbeta-treated mice were markedly less severe than in the control group (P < 0.001). This effect was accompanied by a decrease in total anticollagen IgG levels, a decrease in anticollagen IgG2a, and an increase in IgG1. In vitro, supernatants from these engineered fibroblasts inhibited collagen-induced interferon-gamma secretion from lymph node cells, and reduced the levels of tumor necrosis factor alpha and interleukin-12 produced by lipopolysaccharide/IFNgamma-treated bone marrow-derived macrophages. This effect was specific, since it was reversed with anti-IFNbeta polyclonal antibodies.

CONCLUSION

These results indicate that IFNbeta, which is currently used as a treatment for relapsing, remitting multiple sclerosis, is a potent immunomodulatory and antiinflammatory cytokine in CIA and should be considered for the treatment of rheumatoid arthritis.

TNF-alpha and IFN-gamma render microglia sensitive to Fas ligand-induced apoptosis by induction of Fas expression and down-regulation of Bcl-2 and Bcl-xL

The immune response in the central nervous system (CNS) involves microglial cells which represent intraparenchymal antigen-presenting cells (APC). To control immune effector mechanisms it may be required to induce apoptosis of APC and thereby limit reactivation of T cells that have invaded the CNS. In the present study we investigated the susceptibility of primary murine microglia and of the murine microglial cell line BV-2 to undergo Fas-mediated apoptosis. Whereas resting microglia are resistant to Fas ligand (FasL) treatment, induction of FasL-mediated apoptosis was achieved by treatment with TNF-alpha or IFN-gamma. The effect of these cytokines was paralleled by up-regulation of Fas expression and down-regulation of Bcl-2 and Bcl-xL but not Bax. Activation of microglia by TNF-alpha and IFN-gamma was also accompanied by increased amounts of mRNA for the apoptosis inhibitor FLIP, an effect which did not protect the cells from FasL-induced apoptosis. The FasL-induced cell death pathway in microglia involves reactive oxygen intermediates because the antioxidants N-acetylcysteine and glutathione interfere with induction of apoptosis. Surprisingly, microglia constitutively express FasL on the cell surface. However, blocking of endogenous Fas-FasL interaction with Fas-Fc fusion protein did not enhance the survival of microglia, excluding the possibility of suicide or fratricide mechanisms. By their expression of FasL and their TNF-alpha/IFN-gamma-dependent sensitivity to the pro-apoptotic effect of exogenous FasL, microglial cells may influence the course of T cell-mediated diseases of the CNS.

Central nervous system delivery of interleukin 4 by a nonreplicative herpes simplex type 1 viral vector ameliorates autoimmune demyelination

Multiple sclerosis (MS) is a T cell-mediated organ-specific inflammatory disease leading to central nervous system (CNS) demyelination. On the basis of results obtained in experimental autoimmune encephalomyelitis (EAE) models, MS treatment by administration of antiinflammatory cytokines such as interleukin 4 (IL-4) is promising but is hampered by the limited access of the cytokines to the CNS and by the pleiotropic effects of systemically administered cytokines. We established a cytokine delivery system within the CNS using non-replicative herpes simplex type 1 (HSV-1) viral vectors engineered with cytokine genes. These vectors injected into the cisterna magna (i.c.) of mice diffuse in all ventricular and subarachnoid spaces and infect with high efficiency the ependymal and leptomeningeal cell layers surrounding these areas, without obvious toxic effects. Heterologous genes contained in the vectors are efficiently transcribed in infected ependymal cells, leading to the production of high amounts of the coded proteins. For example, 4.5 ng of interferon gamma (IFN-gamma) per milliliter is secreted into the cerebrospinal fluid (CSF) up to day 28 postinjection (p.i.) and reaches the CNS parenchyma in bioactive form, as demonstrated by upregulation of MHC class I expression on CNS-resident cells. We then exploited the therapeutic potential of the vectors in EAE mice. An HSV-1-derived vector containing the IL-4 gene was injected i.c. in Biozzi AB/H mice at the time of EAE induction. We found the following in treated mice: (1) delayed EAE onset, (2) a significant decrease in clinical score, (3) a significant decrease in perivascular inflammatory infiltrates and in the number of macrophages infiltrating the CNS parenchyma and the submeningeal spaces, and (4) a reduction in demyelinated areas and axonal loss. Peripheral T cells from IL-4-treated mice were not affected either in their antigen-specific proliferative response or in cytokine secretion pattern. Our results indicate that CNS cytokine delivery with HSV-1 vectors is feasible and might represent an approach for the treatment of demyelinating diseases. Advantages of this approach over systemic cytokine administration are the high cytokine level reached in the CNS, the absence of effects on the peripheral immune system, and the long-lasting cytokine production in the CNS after a single vector administration.

Cytokine secretion of myelin basic protein reactive T cells in patients with multiple sclerosis

The objective of this study was to determine whether autoreactive T cells in patients with multiple sclerosis (MS) are polarized and committed in their differentiation to a stable cytokine phenotype or whether the cytokine secretion can be altered. We examined the cytokines secreted by myelin basic protein (MBP) as compared to tetanus toxoid-reactive (TT) T cells in 12 patients with relapsing remitting MS (RR-MS), 9 patients with chronic progressive MS (CP-MS), and 14 normal individuals. A total of 5094 short term T cell lines to MBP and TT were generated in the presence of growth conditions promoting Th1 (IL-12/alpha-IL-4 mAb) or Th2 (IL-4/alpha-IL-12 mAb) cytokine secretion. Antigen-specific cytokine secretion from normals and MS patients could be shifted to a Th1 or Th2 type phenotype depending upon culture conditions, indicating that the phenotype of MBP reactive T cells can be altered even in longstanding chronic progressive MS. There were no significant differences in the cytokine patterns secreted by MBP reactive T cells in patients with MS as compared to normal individuals. However, CP-MS patients tended to have fewer MBP reactive T cells secreting IL-4 when cultured with IL-12/anti-IL-4 mAb and more IFN-gamma secreting MBP reactive T cells when cultured with IL-4/anti-IL-12 mAb as compared to both normal controls and RR-MS, suggesting that cells from these patients might be more polarized or that fewer undifferentiated MBP-reactive cells are present in these individuals. The most striking observation was that in contrast to the RR-MS patients and normal controls, almost none of the MBP reactive T cells secreting cytokines in CP-MS incorporated 3[H]thymidine. This may be due to chronic in vivo stimulation in the presence of IL-12, or because these T cells may have entered a terminally differentiated state. Nonetheless, the ability to alter the cytokine secretion of autoreactive T cell lines even in longstanding autoimmune disease indicates that cytokine therapy might have therapeutic benefits by switching the function of myelin reactive T cells such that they are non-pathogenic.

Seasonal variation of interferon-gamma production in progressive multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system. There is increased interferon (IFN)-gamma secretion in MS patients in vitro, and IFN-gamma administration induces exacerbations of disease suggesting a link between IFN-gamma and disease activity. We observed significantly increased IFN-gamma production in the autumn and winter months compared with the spring and summer months in chronic progressive MS, and this increase was linked to endogenous interleukin (IL)-12 production. Increased seasonal IFN-gamma was not observed in normal control subjects, and there were no seasonal changes in IL-10 in progressive MS. These results suggest a potential environmental link between dysregulated IFN-gamma production and MS disease progression and pathogenesis.

Vitamin D3: a transcriptional modulator of the interferon-gamma gene

1Alpha,25-dihydroxyvitamin D3 [1,25-(OH)2D3] exerts several effects on the immune system, by regulating lymphocyte proliferation, differentiation of monocytes and secretion of cytokines as IL-2, granulocyte-macrophage colony-stimulating factor and IFN-gamma in T cells. Here, we analyze the effect of 1,25-(OH)2D3 on IFN-gamma gene transcription. Transient transfection assays in Jurkat T cells indicate that activation of the IFN-gamma promoter is down-regulated by 1,25-(OH)2D3. This effect is enhanced by retinoid X receptor (RXR), and a functional vitamin D3 receptor (VDR) DNA-binding domain in necessary for repression. We delineated two important promoter regions mainly involved in this modulation. The first of these is situated at the level of a promoter-silencer previously characterized and binds the heterodimer VDR-RXR in electrophoretic mobility shift assay. Residual negative regulation was also detected at the level of the promoter fragment -108 to +64 bp from the transcription start site and, surprisingly, the activity of the IFN-gamma enhancer from -108 to -36 bp in the context of a heterologous promoter was not affected by 1,25-(OH)2D3. Moreover, binding activity for VDR-RXR has been detected in the IFN-gamma minimal promoter, suggesting a possible mechanism of interference with transcription initiation/progression. The overall data indicate that direct modulation of the IFN-gamma promoter activity is one of the possible mechanisms involved in the repressive effect of 1,25-(OH)2D3 on IFN-gamma gene expression.

Heat shock proteins and experimental autoimmune encephalomyelitis. II: environmental infection and extra-neuraxial inflammation alter the course of chronic relapsing encephalomyelitis

We wished to study how infections might trigger relapses of autoimmune diseases such as multiple sclerosis (MS) and encephalomyelitis (EAE). We hypothesized that immune responses to heat shock proteins (hsp) induced by an infection could modulate responses to autoantigens. We induced extra-neuraxial inflammation in SJL mice housed either in specific-pathogen free (SPF) or conventional facilities. Mice in conventional housing are continuously exposed to large numbers of infectious agents. Spleen cell proliferative responses to human HSP60 and bacterial HSP65 were measured as were numbers of cells secreting IFN-gamma or IL-5. Proliferative responses to HSP60 were increased in conventionally housed mice compared to SPF mice and this was associated with skewing of secreted cytokines toward a Th2 pattern. Skewing toward a Th1 pattern was noted in SPF mice. Acute and relapsing EAE was induced in both groups of mice. Acute EAE was, in general, equivalent in all groups. However, SPF mice had more severe relapses than did conventionally housed animals and these differences were amplified by extra-neuraxial inflammation. Immunocytochemical analyses of brains from mice with relapsing EAE showed that increased numbers of brain gamma/delta cells were associated with disease remission. Our data suggest that frequent exposure to infectious agents leads to a relative Th2 skewing of immune responses to hsp and that this is associated with milder, less frequent relapses of EAE. They also support the concept that immune responses to hsp are of potential importance in exacerbating and perpetuating organ-restricted autoimmune diseases.

Elevated interleukin-12 in progressive multiple sclerosis correlates with disease activity and is normalized by pulse cyclophosphamide therapy

Multiple sclerosis is postulated to be a Th1-type cell-mediated autoimmune disease. We investigated cytokine profiles in patients with progressive multiple sclerosis by using intracytoplasmic staining. We found increased IL-12 production by monocytes and increased IFN-gamma production by T cells in untreated patients as compared with controls. In patients treated with methotrexate, methylprednisolone, or cyclophosphamide/methylprednisolone (CY/MP), only CY/MP treatment normalized the elevated IL-12 production. Furthermore, CY/MP-treated patients had decreased IFN-gamma and increased IL-4, IL-5, and TGF-beta expression. Patients followed prospectively before and after starting CY/MP treatment showed a gradual decrease in IL-12 and IFN-gamma production and an increase in IL-4 and IL-5. In vitro, addition of 4-hydroperoxycyclophosphamide, a metabolite of cyclophosphamide decreased IL-12 production in mononuclear cell cultures. When patients were classified as having active or stable disease, IL-12 production correlated with disease activity. In summary, our results demonstrate a Th1-type cytokine bias in peripheral blood mononuclear cells of untreated progressive MS patients that is reversed by CY/MP treatment and is associated with Th2 and TGF-beta (Th3) type responses. These findings provide a basis for immune monitoring of patients with MS and suggest that treatments that downregulate IL-12 may prove to be beneficial in progressive MS.

Selective downregulation of Th1 response by Linomide reduces autoimmunity but increases susceptibility to viral infection in BALB/c and SJL mice

Susceptibility to autoimmunity has been associated with polarization of Th1/Th2 balance in immune system towards the Th1-type of reactivity. We report here that orally administered quinoline-3-carboxamide (Linomide) selectively downregulates Th1 response in BALB/c and SJL mice, leading to reduction of autoimmunity in the BALB/c and SJL models of experimental allergic encephalomyelitis (EAE). This was shown by prevention of EAE in Th1 responding SJL mice and partial downregulation of EAE in Th2-prone BALB/c mice. In a BALB/c model of EAE, in which infection with Semliki Forest A7 virus (SFV-A7) is used for enhancement of autoimmunity, clinical signs of EAE were reduced while mortality due to viral infection in the CNS was enhanced. Selective downregulation of the Th1 response by Linomide also rendered initially resistant SJL mice susceptible to SFV-A7 CNS infection. This was shown by immunohistochemical detection of extensive deposits of viral antigen in numerous perivascular foci within the CNS and abolished virus antigen-specific lymphocyte reactivity in Linomide-treated SJL mice. In addition, analysis of spleen cell cytokine mRNA production profile revealed decreased number of IFN-gamma producing cells in both SJL and BALB/c mice, reduced number of IL-12p40 producing cells in SJL and increased number of 12p40 producing cells in BALB/c mice along with slightly increased IL-4 production in both strains of mice. These results indicate that oral treatment with Linomide induces selective downregulation of Th1 reactivity causing reduction of autoimmunity and increased susceptibility to SFV-A7 CNS infection. Selective downregulation of Th1 response is a desired effect in the treatment of autoimmune diseases but our results suggest that the benefits have to be balanced against the possible loss in immunoprotection against pathogens.

Cytokines: principles and prospects

Cytokines participate in the induction and effector phases of all immune and inflammatory responses. They are therefore obvious tools and targets for strategies designed to promote, inhibit or redirect these responses. However, the complexity of the cytokine network has hindered the widespread clinical application of many cytokines and it has become clear that a deeper understanding of the normal operation of this system in health and disease is needed for the therapeutic potential of cytokines to be fully realized. This review summarizes some of the principles that are now thought to underlie the diverse functions of the interleukins, interferons, colony-stimulating factors and tumour necrosis factors in immune and inflammatory reactions in vivo. Genetic and structural relationships between these cytokines, the regulation of their synthesis, and the structures and functions of their receptors are outlined. Current knowledge of these parameters suggests ways in which multiple positive and negative regulatory mechanisms are integrated to balance cytokine benefits and harm under physiological conditions and offers new prospects for rational exploitation of this system.

Antagonistic Action of IFN-β and IFN-γ on High Affinity Fcγ Receptor Expression in Healthy Controls and Multiple Sclerosis Patients

Monocyte-macrophage activation by IFN-γ is characterized by a pronounced increase of high affinity Fc receptors for IgG (FcγRI), capable of triggering respiratory burst, phagocytosis, Ab-dependent cytotoxicity, and release of proinflammatory cytokines. In view of the antagonism of IFN-β on IFN-γ action, of interest in the chronic inflammatory disorder multiple sclerosis, we examined the possible effect of IFN-β on IFN-γ induction of FcγRI gene expression. We found that IFN-β significantly down-regulated IFN-γ-induced FcγRI surface expression in peripheral blood monocytes from healthy donors, in a dose- and time-dependent manner. This down-regulation of FcγRI surface levels did not correspond to a decrease in FcγRI mRNA, suggesting a posttranscriptional effect of IFN-β. Down-regulation of FcγRI surface expression correlated with diminished cellular signaling through FcγRI, since the IFN-γ-induced increase in Fcγ receptor-triggered respiratory burst was nearly completely abrogated by simultaneous addition of IFN-β. Finally, the same antagonism between both IFNs on FcγRI surface expression was observed in peripheral blood monocytes derived from multiple sclerosis patients; inhibition by IFN-β was even increased (82 ± 11%), as compared with healthy controls (67 ± 4%). These results may partially help explain the beneficial effect of IFN-β in multiple sclerosis.

Pulse cyclophosphamide plus methylprednisolone induces myelin-antigen-specific IL-4-secreting T cells in multiple sclerosis patients

Multiple sclerosis (MS) is a presumed cell-mediated Th1-type autoimmune disease. Thus therapies which decrease T cells secreting IFN-gamma production or increase IL-4 production would be expected to have an ameliorating effect on MS. We have previously reported increased anti-CD3-induced IL-4 secretion by T cells in progressive MS patients treated with cyclophosphamide plus methylprednisolone (CY/MP) which was associated with eosinophilia. To investigate whether the increased IL-4 secretion was myelin antigen specific, we generated 3990 short-term T cell lines to myelin basic protein (MBP), proteolipid protein (PLP), or tetanus toxoid (TT) from 31 progressive MS patients: 11 MS patients treated with CY/MP, 10 MS patients treated with MP alone, and 10 untreated MS patients. We found increased frequencies of both MBP- and PLP-specific IL-4-secreting T cell lines in CY/MP-treated patients compared to untreated MS patients. However, no change in the frequency of TT-specific IL-4-secreting T cells was observed. MP treatment alone did not increase the frequency of antigen-specific IL-4-secreting T cell lines. These results demonstrate immune deviation favoring Th2-type responses specific to autoantigens following pulse cyclophosphamide therapy in MS patients.

Incidence of exacerbations in the first 90 days of treatment with recombinant human interferon beta-1b in patients with relapsing-remitting multiple sclerosis

Interferon beta-1b (IFNbeta-1b) is effective in reducing the frequency of exacerbations in patients with relapsing-remitting multiple sclerosis (RRMS). Recently, a study suggested that treatment with IFNbeta-1b may place MS patients at risk of exacerbations by increasing interferon-gamma (IFNgamma)-secreting cells in the blood early after onset of treatment. We conducted a retrospective study in 192 RRMS patients treated with IFNbeta-1b. We did not observe an increase in the frequency of exacerbations early after the onset of treatment and suggest that the IFNgamma-secreting cell surge linked to the onset of treatment with IFNbeta-1b may not be clinically significant.

Stressor-induced alteration of cytokine production in multiple sclerosis patients and controls

OBJECTIVE

We administered an acute psychological stressor to multiple sclerosis (MS) patients and normal controls to determine whether differences in subjective and physiological responses to stress may underlie the susceptibility of MS patients to stress-related exacerbations.

METHOD

Twenty-five MS patients (18 female, 7 male) and 25 age- and gender-matched controls participated in the study. They were asked to give a 5-minute videotaped speech defending themselves in a hypothetical scenario in which they were wrongly accused of stealing. Subjective and autonomic responses were monitored, and blood was sampled at baseline, 5, 20, and 60 minutes after the stressor to assess mitogen-stimulated production of interleukin-1beta(IL-1beta), interleukin-4 (IL-4), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma).

RESULTS

MS patients and controls demonstrated similar subjective and physiological responses to the stressor that were independent of gender, mood, and disability status. The macrophage-derived cytokines IL-1beta and TNF-alpha were increased during the stressor, and remained elevated through 60 minutes. Th1 lymphocyte-derived IFN-gamma production also was increased at 5 and 60 minutes relative to baseline; however, there was no change in the Th2 lymphocyte-derived cytokine IL-4.

CONCLUSIONS

These results favor the hypothesis that MS patients do not differ in stress response from normal controls; however, psychological stress may enhance cellular immune responses that would be potentially harmful to MS patients.

A gene therapy approach to treat demyelinating diseases using non-replicative herpetic vectors engineered to produce cytokines

A successful gene therapy approach in organ-specific autoimmune diseases, such as multiple sclerosis (MS), encompasses the inhibition of the autoreactive T cells or the modification of the target organ cells by the introduction of exogenous 'protective' genes. In MS, an autoimmune disease of the central nervous system (CNS), the inciting autoantigen is still unknown and therefore the isolation of autoreactive T cells may only be inferential. At present, gene therapy approaches in MS should therefore aim to the modification of the target organ. Possible candidate genes to be transferred within the CNS of MS patients are those coding for anti-inflammatory cytokines (i.e. interleukin-4, interleukin-10, transforming growth factor beta) which have been shown to ameliorate demyelinating diseases at least in experimental models. However, a limiting factor for this therapy is the difficulty to reach the CNS. A gene therapy approach using viral vectors able to infect post-mitotic cells, such as those present within the CNS, without inducing toxic reactions, may overcome this limitation. We propose to use non-replicative herpetic vectors, which represent a viable gene-transfer alternative to the classical retroviral and adenoviral vectors. Key advantages are their size, able to accommodate multiple foreign genes, and their ability to infect post-mitotic cells such as those present within the CNS. We first transferred a gene coding for interleukin-4 within the CNS of mice undergoing experimental allergic encephalomyelitis, an animal model for MS, using non-replicative Herpes Simplex Virus type 1-derived vectors. We found that this approach ameliorates the disease course and delays the disease onset. The establishment of this technique to deliver anti-inflammatory cytokines within the CNS using herpetic vectors should clarify the role of individual cytokines in the demyelinating process and allow assessment of whether gene therapy using herpetic vectors is a feasible and safe approach to treat human demyelinating disorders.

A 21 point unifying hypothesis on the etiology and treatment of multiple sclerosis

Multiple sclerosis (MS) is postulated to be a cell mediated autoimmune disease directed against central nervous system myelin components. Our understanding of the disease has been enhanced by a number of factors: 1) advances in our understanding of the immune system; 2) clinical trials which are beginning to identify treatments which can affect MS; 3) a better understanding of the clinical features of MS; and 4) advances in MRI imaging of the brain. Based on the current state of knowledge, this paper proposes a 21 point unifying hypothesis on the etiology and treatment of the disease. This hypothesis makes a series of assumptions, many of which are unproven, and is presented as a framework from which to investigate and treat the disease, not as a established biology. It is hypothesized that the underlying pathogenesis of MS is related to an inappropriate class of immune response against myelin antigens favoring proinflammatory Th1 versus anti-inflammatory Th2 or Th3 type responses. Environmental and genetic factors predispose toward MS by affecting the class of response and effectiveness of treatment is also related to how it impacts on this common final pathway. Because of epitope spreading, there is not one autoantigen involved in MS and the progressive form of MS differs immunologically from the relapsing remitting form. Viruses trigger and perpetuate MS, although MS is not related to a persistent viral infection. Because MS is a multifactorial disease, there are clinical and perhaps immunological subtypes of MS and a single type of treatment is unlikely to control the disease in all patients. Thus, there will be responders and non-responders to each effective therapy and ultimately combination therapy will be required to cure the disease.

Proinflammatory cytokines regulate antigen-independent T-cell activation by two separate calcium-signaling pathways in multiple sclerosis patients

Central nervous system (CNS) lesions typical of multiple sclerosis (MS) are characterized by demyelinating inflammatory infiltrates that contain few CNS antigen-specific autoreactive T cells and a multitude of pathogenic non-antigen-specific mononuclear cells. Here, we report that in patients with MS the combined action of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNFalpha), interleukin (IL)-2, and IL-6 leads to the activation of most peripheral T cells (mainly CD4 memory) by promoting a persistent intracellular calcium increase via two independent signaling pathways. The activation of these pathways, one activated by IFNgamma and the other by the combination TNFalpha/IL-2/IL-6, is independent from myelin antigens and precedes by 2 weeks phases of disease activity (eg, clinical relapses and/or appearance of gadolinium-enhancing lesions on brain magnetic resonance imaging scans during 1 year of follow-up). Our results indicate that an appropriate combination of the four cytokines, three with a proinflammatory profile and one necessary for T-cell growth and differentiation, can activate in an antigen-independent fashion most peripheral T cells from MS patients. This mechanism is likely to contribute to the recruitment of nonspecific lymphocytes into the cellular activation processes leading to CNS demyelination and may represent a major target for immune intervention in MS.

Effect of propranolol and IFN-beta on the induction of MHC class II expression and cytokine production by IFN-gamma IN THP-1 human monocytic cells

This study was undertaken to investigate the effects of propranolol, IFN-beta, and the protein kinase modulators on IFN-gamma induction of MHC class II antigen expression and cytokine production in THP-1 human monocytic cells. IFN-gamma induced expression of HLA-DR and DQ molecules and secretion of the monokines IL-1 beta and TNF-alpha in THP-1 cells in a time and dose-dependent manner. The effect of INF-gamma on class II HLA antigens was dose-dependently inhibited by IFN-beta. H-7, phloretin, staurosporine as well as GF 109203X are selective enzyme inhibitors of protein kinase C (PKC), down-regulating IFN-gamma induced MHC class II expression and cytokine production. Stimulators of PKC, like PMA, replaced IFN-gamma in the induction of monokines in THP-1 cells, whereas the addition of HA 1004 or arachidonic acid to the culture had no effect on IFN-gamma mediated changes. Blocking of phospholipase D (PLD)-derived diacylglycerol (DAG) formation by propranolol abrogated IFN-gamma increased HLA class II expression and IL-1 beta secretion, but had little effect on IFN-gamma induced TNF-alpha production. These findings appear to suggest that PLD-derived phosphatidate is not the primary source of DAG production in IFN-gamma-induced TNF-alpha secretion, but may be necessary for IFN-gamma-mediated MHC class II induction and IL-1 beta production in human monocytes, whereas phospholipase A2 may not be required for IFN-gamma activation of PKC in the process.

Current immunotherapy in multiple sclerosis

The underlying pathophysiology of multiple sclerosis is presumed to be autoimmune in nature. Attempts to find an effective treatment for this common disease of the central nervous system have primarily focused on immune-mediated therapies, both immunosuppressive and immunomodulatory. The wide variety of immunological abnormalities detected in multiple sclerosis and its animal model, experimental allergic encephalomyelitis, has prompted the testing of a diverse array of drugs to be used for treatment. Recent successes in the treatment of relapsing-remitting multiple sclerosis with interferon beta and glatiramer acetate have renewed interest in and raised expectations for the effective control of this neurological disorder. Improved methodology in clinical trials, the development of surrogate markers and the availability of novel therapies bode well for more rapid advances.

Cell-type specific factors bind to regulatory elements located downstream of the TATA-box element in the mouse myelin basic protein (MBP) gene promoter

Cell-type specific transcription of the myelin basic protein (MBP) gene in primary oligodendrocytes (OL) is regulated by cis-acting regulatory elements located at both upstream and downstream of the TATA-box region of the MBP promoter. To identify cell-type specific factors that bind to the downstream regulatory elements, we utilised DNase I footprinting analysis and gel retardation assays with nuclear extracts from myelin-forming OL as well as a non-myelin forming cell line, C6 glioma (C6) cells. Several regions of DNA were protected from DNAse I digestion by nuclear extracts of both cell types. However, two regions, from -17 to +17 and from +47 to +58 were protected specifically in OL, while three regions, from + 17 to + 22, from +43 to +49 and from +58 to +64 were protected only with C6 nuclear extracts. Inspection of the protected regions for homology with known transcription factor binding sites revealed that sequences at from +47 to +58 and from +56 to +68 showed extensive homology to the negative regulatory element (NRE1), of the mouse renin gene and to the interferon (IFN) consensus sequence of major histocompatibility complex class I genes (MHC I-ICS), respectively. Gel retardation assays using a MHC I-ICS oligonucleotide and transient transfection assays using MBP-CAT constructs were used to study the effect of IFNs on MBP promoter activity in OL and C6 cells. In OL, IFN-alpha/beta caused little induction of CAT activity, but IFN-gamma resulted in a 2-3.5-fold decrease in CAT activity. In contrast, in C6 cells both IFN-alpha/beta and IFN-gamma induced a 1.5-2.5-fold increase in CAT activity. The cooperative effects of factors binding to NREs and ICS may be responsible for the cell-type specific regulation of MBP gene transcription.

Concordance and contradiction concerning cytokines and chemokines in experimental demyelinating disease

Experimental autoimmune encephalomyelitis (EAE) has served as a model for human demyelinating diseases, including multiple sclerosis. EAE is mediated by CD4+ T lymphocytes of the TH1 subset. These T cells produce inflammatory cytokines and chemokines that are associated with pathogenicity. The disease is downregulated by other T cells, presumably of the TH2 subset that secrete a different pattern of cytokines which modulate the activity of the pathogenic TH1 cells. Ongoing studies should provide insight into how the interactions of T-cell subsets impact on the pathogenesis of autoimmune demyelinating diseases.

Role of Th1 and Th2 cells in autoimmune demyelinating disease

Evidence is accumulating that Th1 cells play an important role in the development of multiple sclerosis (MS) and experimental allergic encephalomyelitis (EAE), whereas Th2 cells contribute to recovery from disease. A major determinant in the development of Th1 and Th2 cells is the type of antigen-presenting cell (APC) involved and its functional characteristics, e.g., the production of interleukin-12. Therefore, modulation of APC might interfere with the development of Th1 type responses and as such be beneficial for MS and EAE. The potential of cytokines, in particular interleukin-10, and glucocorticoids to exert a selective effect on APC, and as a consequence to affect the Th1-Th2 balance in EAE, is discussed.

Changes in nitrite and nitrate (NO2-/NO3-) levels in cerebrospinal fluid of patients with multiple sclerosis

To compare the change in nitric oxide (NO) metabolism in patients with multiple sclerosis (MS) in different clinical stages, such as exacerbation, remission, and 1-2 months after methylpredonisolone administration, we measured the nitrite and nitrate (NO2-/NO3-) levels in the cerebrospinal fluid (CSF). In the extreme stage of MS exacerbation, those levels were remarkably elevated, compared with those both after methylpredonisolone administration and remission. These results suggest that, in addition to MRI study, measurement of NO metabolites in the CSF may give information to help us understand the activity of MS and effect of drugs on the disease.

Immune deviation following pulse cyclophosphamide/methylprednisolone treatment of multiple sclerosis: increased interleukin-4 production and associated eosinophilia

Multiple sclerosis (MS) is postulated to be a Th1-type cell-mediated autoimmune disease. Thus therapies that decrease T cell interferon (IFN)-gamma production or increase interleukin (IL)-4 production would be expected to have an ameliorating effect on MS. Some progressive MS patients receiving pulse cyclophosphamide therapy developed peripheral blood eosinophilia. We investigated whether cyclophosphamide-treated patients had immune deviation toward Th2 responses. We measured cytokine production in patients receiving either monthly intravenous methylprednisolone (MP), intravenous cyclophosphamide plus methylprednisolone (CY/MP), methotrexate, IFN-beta1b, in untreated MS patients, and in healthy controls. Minimal IL-4 was secreted in untreated patients (129 +/- 62 pg/ml), methotrexate-treated patients (99 +/- 79 pg/ml), and healthy controls (50 +/- 13 pg/ml). A marked increase in IL-4 was observed in CY/MP patients (1,503 +/- 291 pg/ml). Patients treated with MP (418 +/- 160 pg/ml) or IFN-beta1b (425 +/- 167 pg/ml) showed small increases. Eosinophilia in CY/MP-treated patients (6.0 +/- 0.7%) correlated with increased IL-4. IL-10 production was also increased in CY/MP-treated patients. Both CY/MP- and MP-treated groups had decreased production of IFN-gamma compared with untreated MS. These findings demonstrate pronounced immune deviation favoring Th2-type responses after pulse cyclophosphamide therapy.

Rational clinical immunotherapy for multiple sclerosis

In this article, we assess the roles and the efficacy of immunopharmacologic agents in the treatment of multiple sclerosis (MS) and other demyelinating disease syndromes. The initial clinical manifestations of demyelinating disease, immunotherapeutic goals, efficacy of individual agents, and specific immunopharmacologic recommendations are discussed. MS and other idiopathic demyelinating disease syndromes can be effectively managed with immunotherapy. Exacerbations are treatable, and the frequency and severity of exacerbations can be reduced. Although some agents have a minor effect on progression of disability, current approaches have not proved to have a major influence on treatment of progressive MS. Immunotherapy for inflammatory demyelinating disease necessitates a high degree of clinical certainty about the diagnosis. Because all available therapeutic agents have limitations and significant toxic effects, careful consideration is necessary before use. Treatment should be individualized on the basis of the clinical course of the disease and the degree of patient disability.

Correlation between interferon production and clinical disease activity in patients with multiple sclerosis

We determined the interferon (IFN) serum levels and in vitro activated IFN production in eight patients with relapsing/ remitting multiple sclerosis (MS), using a whole-blood test system and the mitogen concanavalin A and the viral antigen Newcastle disease virus for induction of the IFN production. During the overall study period of 12 months we observed, in relation to clinical disease progression, a biphasic increase in the individual IFN alpha and IFN gamma production. While mitogen-induced IFN gamma synthesis showed a significant augmentation prior to the onset of a new relapse (P < 0.05), virus-induced IFN alpha production showed a temporal delayed increase which was related to clinical remission (P < 0.01). The observed fluctuations in the individual production of both IFN subtypes were not reflected in the sera of the patients. Although the reason for the temporal different imbalance in the production of both IFN subtypes remains unknown, the observed association between increased IFN alpha production and clinical remission emphasizes a possible role for type 1 IFNs in the resolution of the MS relapse.

Soluble CD8 and ICAM-1 in serum and CSF of MS patients treated with 6-methylprednisolone

OBJECTIVE

We studied the effects of large doses of 6-methylprednisolone (6-MP) on serum and cerebrospinal fluid (CSF) soluble CD8 (sCD8) and intercellular adhesion molecule-1 (sICAM-1) levels in clinically active multiple sclerosis (MS) patients.

MATERIAL AND METHODS

Paired serum and CSF samples were from 16 patients with definite MS, treated with 6-MP (1 g daily for 6 d) during an active phase of the disease. sCD8 and sICAM-1 levels were determined with ELISA before and after the therapy.

RESULTS

Before 6-MP treatment, sCD8 levels in CSF were higher in MS patients than in patients with noninflammatory neurological disease and in healthy controls; sICAM-1 levels in serum and in CSF were higher in MS patients than in the two control groups. Ten of the 16 patients showed clinical improvement at the end of the treatment. After the therapy, serum and CSF sCD8 levels increased, whereas serum and CSF sICAM-1 levels decreased. There was no correlation between clinical improvement and laboratory parameters. We evaluated sCD8 and sICAM-1 in serum samples from 10 patients 6 months after the 6-MP treatment, when the disease was clinically silent. Neither sCD8 nor sICAM-1 levels differed from those of the control groups.

CONCLUSIONS

Our results suggest that high doses of 6-MP can influence serum and CSF sCD8 and sICAM-1 levels in active MS. At least part of the efficacy of corticosteroid treatment in MS might be ascribed to its effect both on the suppressive circuits of immune response, and on the expression of an adhesion molecule that favours lymphocyte trafficking across the blood-brain barrier.

Interleukin-12 and tumor necrosis factor-alpha levels in cerebrospinal fluid of multiple sclerosis patients

Concentrations of interleukin (IL)-12 and tumor necrosis factor-alpha (TNF-alpha) in cerebrospinal fluid (CSF) were measured in patients with multiple sclerosis (MS) and control patients with non-inflammatory neurological diseases (NIND) by an enzyme-linked immunosorbent assay. TNF-alpha was detectable in the CSF of 60% of the patients with active MS, none of those with inactive MS and 29% of patients with NIND. CSF concentrations of TNF-alpha correlated with the degree of disability in MS patients (P < 0.05). Detectable levels of IL-12 were found in 10% of the MS CSF samples and 18% of NIND CSF samples. There was a significant relationship between CSF concentrations of IL-12 and those of TNF-alpha in MS patients (P < 0.05); no relationship was observed between the presence of IL-12 and disease activity or severity. These findings further stress the involvement of T helper 1 type-response within the central nervous system in MS.

Interferon-gamma induced increases in intracellular cathepsin B activity in THP-1 cells are dependent on RNA transcription

Interferon-gamma (IFN-gamma) treatment of human macrophages induces increased intracellular levels of cathepsin B (CB), a lysosomal cysteine proteinase which is implicated in inflammatory tissue injury. To determine the mechanism of the increase, we studied the macrophage-like cell line, THP-1. Dose and time dependent increases in intracellular CB were seen when cells primed with phorbol ester (PMA) were cultured with IFN-gamma. To determine whether protein synthesis was required for the increase, PMA primed cells were cultured in the presence of IFN-gamma and cycloheximide: The expected increase was inhibited. To determine whether RNA synthesis was required for the IFN-gamma induced increases, PMA primed cells were cultured in the presence of IFN-gamma and actinomycin D. Again the expected increases were not seen. Direct measurement of CB mRNA levels showed increases in cells not treated with inhibitors. These results suggest that the IFN-gamma induced increases in THP-1 cell CB are dependent on RNA and protein synthesis.

Nursing management of MS patients receiving interferon beta-1b therapy

In 1993, recombinant interferon beta-1b (Betaseron, Berlex Laboratories) was approved by the Food and Drug Administration as a treatment for relapsing-remitting multiple sclerosis (MS). Betaseron is the first therapeutic agent licensed for use with therapeutic patients with MS in more than 20 years. Many patients and their families have expressed great interest in obtaining information about this agent. In response, MS centers throughout the United States have developed Betaseron training programs. This article describes how rehabilitation nurses can educate patients and families about Betaseron.

Increased interleukin 12 production in progressive multiple sclerosis: induction by activated CD4+ T cells via CD40 ligand

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system postulated to be a cell-mediated autoimmune disease in which interferon gamma (IFN-gamma) plays an important role. There is increased IFN-gamma secretion in MS, and IFN-gamma administration induces exacerbations of disease. We found that interleukin 12 (IL-12) was responsible for raised IFN-gamma secretion in MS as anti-IL-12 antibodies reversed raised anti-CD3-induced IFN-gamma in MS patients to normal levels. Furthermore, we found a marked increase in T cell receptor-mediated IL-12 secretion in progressive MS patients vs. controls (24.8 +/- 7.7 pg/ml vs. 1.5 +/- 1.0 pg/ml, P = 0.003) and vs. relapsing-remitting patients (3.7 +/- 1.4 pg/ml, P < 0.05). Investigation of the cellular basis for raised IL-12 demonstrated that T cells from MS patients induced IL-12 secretion from non-T cells, and that T cells from MS patients could even drive non-T cells from normal subjects to produce increased IL-12. Anti-CD40 ligand antibody completely blocked IL-12 secretion induced by activated T cells, and we found increased CD40 ligand expression by activated CD4+ T cells in MS patients vs. controls. The CD40 ligand-dependent Th1-type immune activation was observed in the progressive but not in the relapsing-remitting from of MS, suggesting a link to disease pathogenesis and progression and providing a basis for immune intervention in the disease.

Potential therapeutic use of antibodies directed towards HuIFN-gamma

IFN-gamma is an important regulator of immune responses and inflammation. Studies in animal models of inflammation, autoimmunity, cancer, transplant rejection and delayed-type hypersensitivity have indicated that administration of antibodies against IFN-gamma can prevent the occurrence of diseases or alleviate disease manifestations. Therefore, it is speculated that such antibodies may have therapeutical efficacy in human diseases. Since animal-derived antibodies are immunogenic in patients several strategies are being developed in order to reduce or abolish this human anti-mouse antibody (HAMA) response. In our laboratory, we have constructed a single-chain variable fragment (scFv) derived from a mouse antibody with neutralizing potential for human IFN-gamma. A scFv consists of only variable domains tethered together by a flexible linker. The scFv was demonstrated to neutralize the antiviral activity of HuIFN-gamma in vitro and therefore might be considered as a candidate for human therapy.

Chronic relapsing experimental autoimmune encephalomyelitis (CREAE) in mice: enhancement by monoclonal antibodies against interferon-gamma

Experimental autoimmune encephalomyelitis (EAE) is a T cell-mediated inflammatory and demyelinating disorder of the central nervous system. Depending on the experimental conditions, it takes an acute monophasic or a chronic relapsing-remitting course. We have previously reported that the incidence and severity of acute EAE in mice are reduced by administration of interferon (IFN)-gamma and augmented by treatment with neutralizing antibodies against IFN-gamma. Here, we investigated the role of IFN-gamma in chronic relapsing models of EAE (CREAE) in SJL/J and Biozzi ABH mice. Spontaneous relapses in Biozzi mice as well as induced relapses in SJL/J mice were facilitated by administration of neutralizing monoclonal antibody (mAb) against IFN-gamma in the disease-free interval. The enhancing effect of anti-IFN-gamma mAb given before and during the primary attack did not carry over to the relapses. However, early administration of IFN-gamma in Biozzi mice, which developed spontaneous relapses in a high proportion, provided partial protection not only against the first attack, but also against subsequent relapses. Administration of exogenous IFN-gamma during the remission phase provided some protection against subsequent relapses. These results indicate that in both types of relapses, IFN-gamma is produced and does provide a certain degree of protection against disease progression.

Investigational drug therapies of treatment of multiple sclerosis

The licensing of interferon beta-1b dramatically changed the treatment of multiple sclerosis (MS) in the United States. Although it was the first therapeutic agent shown to affect the natural course of the disease, interferon beta-1b is not appropriate for all patients and is far from being a cure. Several other promising therapies now under study include immunosuppressive and immunomodulatory drugs to limit inflammation; oral administration of myelin to induce tolerance; monoclonal antibodies designed to deliver targeted immunotherapy; potassium channel blockers to facilitate conduction along demyelinated axons; and glial growth factors to promote remyelination. Clinical trials of potential therapeutic agents have proliferated in the past decade in conjunction with rapid advances in our understanding of the immunologic basis of MS. Some investigational therapies are associated with problematic toxicities, others benefit only a minority of patients, and many are still in the early stages of development. Nevertheless, because current therapeutic options are limited, and because the history of MS therapy is one of disappointment and frustration, it is essential that legitimate, scientifically based advances be widely disseminated to the neurologic community. This article reviews some of the most promising current and investigational therapies for MS.

Gamma interferon induced increases in intracellular cathepsin B activity in PMA primed THP-1 cells are blocked by inhibitors of protein kinase C

Macrophage proteinases including cathepsin B (CB) are implicated in the tissue injury of inflammatory lesions. We have previously shown that interferon-gamma (IFN-gamma) increases intracellular levels of the lysosomal proteinase, CB, in THP-1 cell primed with phorbol 12-myristate 13-acetate (PMA). We have now examined the role of protein kinase C (PKC) in this effect. Following activation with PMA, the intracellular CB activity was significantly increased in the presence of 500 U/ml IFN-gamma. With the addition of protein kinase C (PKC) inhibitors bisindolylmaleimide, staurosporine, H-7, or phloretin a reversal of the effect of IFN-gamma was noted whereas the addition of the cyclic nucleotide-dependent protein kinase inhibitors HA 1004, H-8, H-89, or cAMP-Dependent Protein Kinase (PKA) Inhibitor did not block the effect. Although diacylglycerol (DAG) did not replace PMA in the study. Diacylglycerol Kinase Inhibitor induced a more pronounced augmentation and PKC depletion inhibited the effect. This suggests that a PKC-dependent pathway is involved in the response of CB in PMA primed THP-1 cells to IFN-gamma.

T-lymphocyte immunointerferon receptors in patients with multiple sclerosis

Multiple sclerosis (MS) is a T-cell-mediated autoimmune demyelinating disease of the central nervous system (CNS), associated with an altered immunoregulation. Interferon (IFN)-gamma, also known as immune IFN, is a cytokine with several effects on the immune system. Specific IFN-gamma receptors have been found on human lymphocytes, as well as on other cell types (e.g. gliocytes), even in the CNS. The aim of the present study was to evaluate IFN-gamma binding on peripheral blood T-lymphocytes from MS patients, compared with those from healthy subjects. Thirty-two patients were selected according to the classical criteria for definite MS; as controls, 21 healthy subjects were studied. We have found that T-lymphocytes from MS patients bear a significantly smaller amount of IFN-gamma receptors than those from controls [Bmax: 568, 18 vs 708, 14 (mean, SE) receptors/ cell]. Such IFN-gamma binding sites are of the same type in patients and healthy subjects [Kd: 1.0, 0.05 vs 0.9, 0.02 (mean, SE) nM]. These findings are discussed in terms of immunopathogenesis of MS, since it has been reported that activated T-lymphocytes have decreased amounts of IFN-gamma receptors.

Interferon-gamma confers resistance to experimental allergic encephalomyelitis

In experimental allergic encephalomyelitis (EAE), T cells infiltrate the central nervous system (CNS) and induce inflammation. These CD4+ T cells secrete interferon (IFN)-gamma, levels of which correlate with disease severity, and which is proposed to play a key role in disease induction. Many strains of mice are resistant to EAE. We have studied the effect of deletion of IFN-gamma on the ability to induce EAE in resistant BALB/c-backcrossed mice. As expected, only 0-6% of BALB/c or BALB/c-backcrossed mice developed EAE when immunized with myelin basic protein in adjuvant. Strikingly, abrogation of IFN-gamma expression by targeted disruption of the IFN-gamma gene (GKO mice) converted them to a susceptible phenotype. As many as 71% of these IFN-gamma-deficient mice developed EAE, a frequency comparable to that seen with the susceptible SJL/J strain. In addition, EAE was of unusually high severity in mice lacking IFN-gamma. Immunological characteristics of disease in IFN-gamma-deficient mice were comparable to those seen in susceptible (SJL/J) mice with EAE, including perivascular infiltration in the CNS and order-of-magnitude increases for both CD3 gamma chain and TNF-alpha mRNA levels in the spinal cord. We thus demonstrate that lack of IFN-gamma converts an otherwise EAE-resistant mouse strain to become susceptible to disease. Therefore, in BALB/c mice, IFN-gamma confers resistance to EAE.

In vitro immunopharmacologic effect of suramin on modifying Th-subset cytokine levels in splenocytes and T-cell clones: a therapeutic application for autoimmune disease

The in vitro immunopharmacologic effect of suramin, a polysulfonated napthylurea, was examined on splenocytes and T helper (Th) 1 and 2 clones. Cytokine capture assays revealed that suramin inhibited the production of IFN-gamma, whilst IL-4 is increased in splenocytes. To examine whether suramin preferentially acts on Th cells, clones SP39A1 and SP41D5 were used. The former is a Th1 clone, whereas the latter is Th2. Suramin also inhibited IFN-gamma production by SP39A1, whilst IL-4 production by SP41D5 was enhanced. The action of suramin was of a dose-dependent nature. With regards to T cell proliferation, suramin inhibited the proliferation of both SP39A1 and SP41D5. The ability of suramin to manipulate Th subset cytokine balance can render it a feasible therapeutic agent in autoimmune disorders such as multiple sclerosis.

Detection of altered T helper 1 and T helper 2 cytokine production by peripheral blood mononuclear cells in patients with multiple sclerosis utilizing intracellular cytokine detection by flow cytometry and surface marker analysis

Production of T helper 1 and T helper 2 cytokines was investigated in peripheral blood mononuclear cells (PBMCs) from multiple sclerosis (MS) patients by a newly described technique, detection of intracellular cytokines by flow cytometry in conjunction with immunophenotype analysis. T-cell gamma interferon (IFN-gamma) production and interleukin 10 (IL-10) production were examined after PBMC activation with T-cell mitogens at 5 and 24 h, and monocyte spontaneous production of IL-10 and production after PBMC activation with lipopolysaccharide (LPS) for 24 h were also examined. The data indicate that MS patients have decreased percentages of T cells capable of secreting IFN-gama compared with healthy controls, and this change is detectable at 5 and 24 h. the patients displaying decreased T-cell production of IFN-gamma were essentially confined to a group being treated with the newly approved drug Betaseron (berlex Labs, Cedar Knolls, N.J.), a recombinant form of IFN-beta (rIFN-beta 1b). By gating of the entire lymphocyte population, analysis of IFN-gama production in T cells (CD3+ versus that in non-T cells (CD3+) was possible. The percentage of IFN-gamma-producing lymphocytes that was made up of T cells was essentially unchanged between the Betaseron-treated patients, non-Betaseron-treated patients, and controls, indicating that the suppression of IFN-gamma production displayed by betaseron-treated MS patients was a nonspecific suppression of all IFN-gamma-producing lymphocytes as opposed to a suppression of T-cell production only. The data seem to indicate that treatment of MS with Betaseron corresponds to an inhibition of the lymphocyte's ability to produce IFN-gamma. No changes were detected in T-cell production of IL-10 at either time point. We also observed that MS patients in general appear to have small percentages of peripheral blood monocytes spontaneously producing slight but detectable levels of IL-10. No difference was seen regarding monocyte production of IL-10 after PBMC activation with LPS between MS patients and controls. Both populations responded with high percentages of monocytes producing IL-10. The data seem to indicate that treatment of MS with Betaseron, known to decrease the exacerbation rate of relapsing-remitting MS, corresponds to a suppression of peripheral blood lymphocyte production of IFN-gamma. Monocyte production of IL-10 may also play a role in regulating the disease process.

Interferon-gamma in autoimmunity

Autoimmune disorders are characterized by abrogation of self-tolerance, resulting in emergence of activated self-reactive lymphocyte clones that trigger or maintain inflammatory reactions in specific organs. Interferon-gamma (IFN-gamma), as well as other cytokines, plays an important role as a regulator of the activation of self-reactive lymphocytes and of bystander and accessory cells that are involved in the autoimmune inflammatory response. In experimental models of autoimmunity, endogenous IFN-gamma has invariably been found to profoundly affect the disease course. However, it acts in one way in some diseases and in the opposite way in others.

Heat shock proteins and experimental autoimmune encephalomyelitis (EAE): I. Immunization with a peptide of the myelin protein 2',3' cyclic nucleotide 3' phosphodiesterase that is cross-reactive with a heat shock protein alters the course of EAE

We describe sequence similarity and immunologic cross-reactivity between a peptide of the mycobacterial hsp, HSP65, and the myelin protein 2',3' cyclic nucleotide 3' phosphodiesterase (CNP). We demonstrate that immunization with the homologous cross-reactive CNP peptide (hsp-CNP peptide) has significant biological consequences. Rats immunized with hsp-CNP peptide in either complete Freund's adjuvant (CFA) or incomplete Freund's adjuvant (IFA) produce large amounts of peptide-specific antibody. Isotypes of antibodies in animals immunized with peptide in CFA are IgG1 and IgG2a. Isotypes of antibodies in rats immunized with peptide in IFA are predominantly IgG1, with low titers of IgG2a. T cell proliferative responses to HSP65 are present in rats immunized with peptide in CFA. T cell responses to HSP65 initially are absent in rats immunized with peptide in IFA but develop over time. T cell proliferative responses to hsp-CNP peptide were not detected. None of the groups of rats developed clinical or histologic evidence of experimental autoimmune encephalomyelitis (EAE). To induce EAE, rats preimmunized with hsp-CNP peptide were challenged with guinea pig spinal cord (GPSC) emulsified in CFA. Rats preimmunized with peptide in CFA developed severe EAE. Rats preimmunized with hsp-CNP peptide in IFA were protected from EAE, with both a lower incidence and severity of disease. Injecting the murine monoclonal antibody recognizing the shared HSP65 and CNP epitope did not protect against EAE. Our data suggest that a Th2 pattern of immune response to a CNP peptide that itself is non-encephalitogenic protects against EAE. Immune responses to either hsp or myelin proteins cross-reactive with hsp may play an important role in the development of EAE.