Sulfasalazine aggravates experimental autoimmune encephalomyelitis and causes an increase in the number of autoreactive T cells

Treatment approaches to patients with multiple sclerosis and coexisting autoimmune disorders

The past decades have yielded major therapeutic advances in many autoimmune conditions - such as multiple sclerosis (MS) - and thus ushered in a new era of more targeted and increasingly potent immunotherapies. Yet this growing arsenal of therapeutic immune interventions has also rendered therapy much more challenging for the attending physician, especially when treating patients with more than one autoimmune condition. Importantly, some therapeutic strategies are either approved for several autoimmune disorders or may be repurposed for other conditions, therefore opening new curative possibilities in related fields. In this article, we especially focus on frequent and therapeutically relevant concomitant autoimmune conditions faced by neurologists when treating patients with MS, namely psoriasis, rheumatoid arthritis and inflammatory bowel diseases. We provide an overview of the available disease-modifying therapies, highlight possible contraindications, show pathophysiological overlaps and finally present which therapeutics can be utilized as a combinatory treatment, in order to 'kill two birds with one stone'.

Chronic Sulfasalazine Treatment in Mice Induces System xc - - Independent Adverse Effects

Despite ample evidence for the therapeutic potential of inhibition of the cystine/glutamate antiporter system x_c⁻ in neurological disorders and in cancer, none of the proposed inhibitors is selective. In this context, a lot of research has been performed using the EMA- and FDA-approved drug sulfasalazine (SAS). Even though this molecule is already on the market for decades as an anti-inflammatory drug, serious side effects due to its use have been reported. Whereas for the treatment of the main indications, SAS needs to be cleaved in the intestine into the anti-inflammatory compound mesalazine, it needs to reach the systemic circulation in its intact form to allow inhibition of system x_c⁻. The higher plasma levels of intact SAS (or its metabolites) might induce adverse effects, independent of its action on system x_c⁻. Some of these effects have however been attributed to system x_c⁻ inhibition, calling into question the safety of targeting system x_c⁻. In this study we chronically treated system x_c⁻ - deficient mice and their wildtype littermates with two different doses of SAS (160 mg/kg twice daily or 320 mg/kg once daily, i.p.) and studied some of the adverse effects that were previously reported. SAS had a negative impact on the survival rate, the body weight, the thermoregulation and/or stress reaction of mice of both genotypes, and thus independent of its inhibitory action on system x_c⁻. While SAS decreased the total distance travelled in the open-field test the first time the mice encountered the test, it did not influence this parameter on the long-term and it did not induce other behavioral changes such as anxiety- or depressive-like behavior. Finally, no major histological abnormalities were observed in the spinal cord. To conclude, we were unable to identify any undesirable system x_c⁻-dependent effect of chronic administration of SAS.

Early termination of ISRCTN45828668, a phase 1/2 prospective, randomized study of sulfasalazine for the treatment of progressing malignant gliomas in adults

BACKGROUND

Sulfasalazine, a NF-kappaB and x(c)-cystine/glutamate antiport inhibitor, has demonstrated a strong antitumoral potential in preclinical models of malignant gliomas. As it presents an excellent safety profile, we initiated a phase 1/2 clinical study of this anti-inflammatory drug for the treatment of recurrent WHO grade 3 and 4 astrocytic gliomas in adults.

METHODS

10 patients with advanced recurrent anaplastic astrocytoma (n = 2) or glioblastoma (n = 8) aged 32-62 years were recruited prior to the planned interim analysis of the study. Subjects were randomly assigned to daily doses of 1.5, 3, 4.5, or 6 grams of oral sulfasalazine, and treated until clinical or radiological evidence of disease progression or the development of serious or unbearable side effects. Primary endpoints were the evaluation of toxicities according to the CTCAE v.3.0, and the observation of radiological tumor responses based on MacDonald criteria.

RESULTS

No clinical response was observed. One tumor remained stable for 2 months with sulfasalazine treatment, at the lowest daily dose of the drug. The median progression-free survival was 32 days. Side effects were common, as all patients developed grade 1-3 adverse events (mean: 7.2/patient), four patients developed grade 4 toxicity. Two patients died while on treatment or shortly after its discontinuation.

CONCLUSION

Although the proper influence of sulfasalazine treatment on patient outcome was difficult to ascertain in these debilitated patients with a large tumor burden (median KPS = 50), ISRCTN45828668 was terminated after its interim analysis. This study urges to exert cautiousness in future trials of Sulfasalazine for the treatment of malignant gliomas.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN45828668.

Inhibiting cytokines of the interleukin-12 family: recent advances and novel challenges

Interleukin-12 (IL-12) and the more recently discovered IL-23 and IL-27 constitute a unique family of structurally related, heterodimeric cytokines that regulate cell-mediated immune responses and T helper 1 (Th1)-type inflammatory reactions. Not surprisingly, the potentiality of treating conditions such as multiple sclerosis (MS) and rheumatoid arthritis (RA) through pharmacological interference with IL-12 pathways has received widespread attention. In this review we have examined over 50 substances with reported IL-12 inhibitory effects. We demonstrate that a majority of these belong to a limited number of major functional classes, each of which targets discrete events in the IL-12 biological pathway. Thus, most IL-12 inhibitory substances appear to work either through inhibition of transcription factor NF-kappa B activation, up-regulation of intracellular cAMP, blockage of posttranslational processing or interference with signal transduction pathways. In addition, cyclophilin-binding drugs, and generic inhibitors of nuclear histone deacetylases, and of ion channels, pumps and antiporters are emerging as potential leads to novel targets for interference with IL-12 production. Many inhibitors of NF-kappa B and of IL-12 signal transduction have been proven effective in limiting or preventing disease in experimental autoimmune encephalomyelitis (EAE) models of MS. The sharing of the p40 subunit, the IL-12R beta 1 and components of the signal transduction pathways between IL-12 and IL-23 raises the question as to whether the beneficial effects of various drugs previously ascribed to inhibition of IL-12 may, in fact, have been due to concurrent blockage of both cytokines, or of IL-23, rather than IL-12. Moreover, the homodimeric beta(2)-form of IL-12, though originally considered to display only antagonistic effects, is now emerging as a pronounced agonist in a variety of inflammatory processes. Reassessment of IL-12 inhibitory compounds is therefore needed to scrutinize their effects on IL-12 alpha beta, beta(2) and IL-23 formation. This is likely to open exciting perspectives to the identification of drugs that target these cytokines either indiscriminately or selectively. The functional diversity of presently available inhibitors should facilitate an unprecedented flexibility in designing future trials for the treatment of IL-12- and IL-23-mediated disorders.

Protracted, relapsing and demyelinating experimental autoimmune encephalomyelitis in DA rats immunized with syngeneic spinal cord and incomplete Freund's adjuvant

Experimental autoimmune encephalomyelitis (EAE) is a model for multiple sclerosis (MS). However, MS is a chronic, relapsing and demyelinating disease, whereas EAE in rats is typically a brief and monophasic disorder showing little demyelination. We demonstrate here that DA rats develop severe, protracted and relapsing EAE (SPR-EAE) after a subcutaneous immunization at the tail base with syngeneic spinal cord and incomplete Freund's adjuvant (IFA). The neurological deficits were accompanied by demyelinating inflammatory lesions in the spinal cord, with infiltrating T lymphocytes and perivascular deposition of immunoglobulins and complement. The induction of SPR-EAE was associated with humoral autoreactivity to myelin oligodendrocyte glycoprotein (MOG) and cellular autoreactivity to the rat myelin basic protein (MBP) peptides 69-87 and 87-101. These two peptides, as well as whole rat MBP, were encephalitogenic. In conclusion, we believe that the presently described demyelinating SPR-EAE represents a useful model for MS.

Critical influences of the cytokine orchestration on the outcome of myelin antigen-specific T-cell autoimmunity in experimental autoimmune encephalomyelitis and multiple sclerosis

In EAE/MS, effector molecules are produced as a result of the interaction between T lymphocytes and antigen-presenting cells and the spectrum of cytokines produced is likely to decisively influence the disease outcome. These events may be more important, or at least more easily accessible to therapeutic intervention, than particular autoantigen specificities. Data from EAE suggest that cytokines connected to the Th1 phenotype of lymphocytes, especially IFN-gamma but also TNF-beta, TNF-alpha and IL-12, may promote inflammation while cytokines connected to the Th2 subset, IL-4, IL-10 and TGF-beta, may potentially have a role in disease limitation. It will be important to accurately study cytokines during immunotherapeutic interventions and in relation to immunogenetic variables in order to aim at immunotherapeutically intervening in the Th1, Th2 balance as well as counteracting disease-promoting cytokines such as IFN-gamma and TNF-alpha or promoting the action of downregulatory cytokines such as IL-10 and TGF-beta.

Interferon gamma, interleukin 4 and transforming growth factor beta in experimental autoimmune encephalomyelitis in Lewis rats: dynamics of cellular mRNA expression in the central nervous system and lymphoid cells

The potential role of certain important immunoregulatory and effector cytokines in autoimmune neuroinflammation have been studied. We have examined the expression of mRNA, with in situ hybridization, of interferon gamma (IFN-gamma), interleukin 4 (IL-4) and transforming growth factor beta (TGF-beta) both in sections of spinal cords and the antigen-induced expression of these cytokines by lymphoid cells after stimulation with a dominant encephalitogenic peptide of MBP (MBP 63-88) during the course of actively induced experimental autoimmune encephalomyelitis (EAE) in Lewis rats. In spinal cords, the target organ in EAE, cells expressing mRNA for IFN-gamma, first appeared at the onset of clinical signs, i.e., day 10 postimmunization (p.i.), peaked at the height of disease (day 13 p.i.) and then gradually decreased concomitant with recovery. Very few IL-4 mRNA-expressing cells appeared in the spinal cord with no clear relation to clinical signs or histopathology. In contrast, expression of mRNA for TGF-beta did not increase until day 13 p.i., at height of the disease, shortly preceding recovery. These data are consistent with a disease upregulating role of IFN-gamma, while TGF-beta may act to limit central nervous system (CNS) inflammation. In lymphoid organs, primed MBP 63-88 reactive T cells showed an interesting time-dependent evolution of their cytokine production in vitro. Thus, early after immunization there was a conspicuous MBP 63-88-induced production of both IFN-gamma and IL-4. Such cells may act in the initiation and promotion of the disease. Later, in the recovery phase, MBP 63-88 induced lymphoid cells to TGF-beta production. Thus, an autoantigen-specific production of TGF-beta occurred during EAE and hypothetically such a mechanism may serve to downregulate aggressive autoimmunity systemically.

Multiple sclerosis:cerebrospinal fluid

Examination of cerebrospinal fluid (CSF) in the context of multiple sclerosis (MS), is valuable for several reasons. First, routine diagnostic evaluation of CSF cell counts and various forms of immunoglobulin determination are important to differentiate MS from other diseases. Second, because MS most probably is an organ-specific inflammatory disease and CSF is often the closest one can get to the target organ, examination of this fluid may allow basic studies on the immunopathogenesis of the disease, and indications of different aspects of inflammation should be considered when evaluating treatments aimed at reducing central nervous system inflammation. This article describes measurements taken at the cellular level in blood and CSF, of myelin-antigen autoreactive B- and T-cell responses, as well as cytokine production. Patients with MS display greatly increased numbers of cells in the CSF that produce antibodies against a variety of myelin antigens, such as myelin basic protein, proteolipid protein, and myelin-oligodendrocyte glycoprotein. Such antibodies may promote demyelination, and autoreactive B cells may enhance antigen presentation to T cells. There is also an increased number of T cells in MS, which in response to a broad range of myelin antigens and peptides, produce cytokines. The production of interferon-gamma, belonging to the T helper-1 type of cells, may have a disease up-regulatory role, while production of other cytokines, such as transforming growth factor beta, may counteract disease. Accurate measurements of cellular production of cytokines will be important in the design and monitoring of immunotherapy.

Immunopharmacologic modulation of experimental allergic encephalomyelitis: low-dose cyclosporin-A treatment causes disease relapse and increased systemic T and B cell-mediated myelin-directed autoimmunity

Therapies with immunosuppressive drugs in autoimmune experimental diseases often down-regulate disease but sometimes may lead to paradoxical disease exacerbation. To elucidate possible mechanisms behind such phenomena the effects were studied of mitoxantrone (Mx) and cyclosporin A (CsA) given at high and low doses on clinical course, and on autoreactive T- and B-cell responses in actively induced experimental allergic encephalomyelitis (EAE) in Lewis rats. Treatment with Mx and high dose CsA abrogated EAE and decreased dramatically the measured immune responses compared to vehicle-treated control EAE rats. Low-dose CsA treatment caused a disease relapse 20-30 days post immunization (p.i.). This relapse was accompanied by increased numbers of cells spontaneously producing IFN-gamma in the CNS and regional lymph nodes. Furthermore, anti-myelin and anti-MBP secreting cells were increased as were numbers of primed T cells that produced IFN-gamma in response to myelin antigens. It was concluded that these aspects of the myelin autoreactive immune response correlated well with clinical disease and are useful in evaluating immunotherapeutic intervention. Low-dose CsA treatment may interfere with systemic down-regulatory mechanisms acting on both T- and B-cell myelin-directed autoimmunity.

Autoreactive T and B cell responses to myelin antigens after diagnostic sural nerve biopsy

To study whether nervous tissue trauma provokes myelin antigen autoreactive T and B cell responses in humans we examined consecutive blood samples from 7 patients with polyneuropathy undergoing diagnostic sural nerve biopsy and 8 control patients undergoing other types of minor surgery. The antigen-specific T cells were assessed by enumerating cells secreting interferon-gamma (IFN-gamma) in response to the myelin components P0, P2, myelin basic protein (MBP) and myelin associated glycoprotein (MAG), and to 4 selected MBP peptides. B cell mediated immunity was assessed by counting numbers of cells secreting antibodies directed against the myelin proteins. On day 7 after biopsy, there were 3-10-fold increased numbers of T and B cells reactive with P0, P2, MBP and MAG in blood of polyneuropathy patients compared to controls, while levels of cells recognizing purified protein derivate or responding to phytohemagglutinin (PHA) did not differ significantly. Comparison of prebiopsy levels on day 0 with post-biopsy levels on day 7 in the polyneuropathy patients revealed a significant increase in T cells recognizing P0, P2 and MAG, and in B cells secreting IgG antibodies against P0 and P2. On day 14 after nerve biopsy these differences were no longer seen. We suggest that in patients with polyneuropathy, sural nerve biopsy with the ensuing wallerian degeneration and myelin breakdown causes transiently increased levels of circulating myelin autoreactive T and B cells. It remains to be determined if this has a physiological role in nerve trauma responses and/or affects the clinicopathological course of the peripheral neuropathy.

Effects of zimeldine and its metabolites, clomipramine, imipramine and maprotiline in experimental allergic neuritis in Lewis rats

The influence of the selective serotonin (5-HT) reuptake inhibiting antidepressant zimeldine and its metabolite norzimeldine was tested on experimental allergic neuritis (EAN) in Lewis rats, which is an animal model of the Guillain-Barré syndrome (GBS) in man. Zimeldine and norzimeldine both suppressed clinical signs of actively induced EAN when given at a dose of 20 mg/kg/day intraperitoneally via osmotic pumps. The effects of zimeldine, its metabolites norzimeldine and CPP 200 as well as of the antidepressants clomipramine, imipramine and maprotiline on in vitro immune response were tested. Thereby we used an immunospot assay for interferon-gamma (IFN-gamma) produced by lymph node mononuclear cells (MNC), which reflects number of memory T lymphocytes activated by antigen or lectin, in this experiment bovine peripheral nerve myelin (BPM) and phytohemagglutinin (PHA), respectively. In the IFN-gamma secretion assay zimeldine, CPP 200, clomipramine and maprotiline all in a concentration-dependent mode reduced the number of IFN-gamma secreting cells while norzimeldine and imipramine did not affect the IFN-gamma secretion. In assays for proliferation in response to antigen or lectin, the concentration 10(-4) M was judged toxic for all substances tested, and at concentrations below that all but zimeldine showed a dose-dependent slight reduction of MNC proliferation. The action of several drugs on induced T cell secretion of IFN-gamma suggests that the mechanisms for the suppressive effect of zimeldine and norzimeldine on EAN symptoms can be due to an action on myelin T cell autoreactivity. All the monoamine reuptake inhibiting antidepressants tested in this study showed immunomodulatory effects by either a reduction of the number of IFN-gamma-secreting cells or the MNC proliferation. These observations call for further studies of immunological mechanisms in the pathogenesis of mental disorders as well as on the potential role of drugs acting on the monoamine systems in the treatment of recognized autoimmune diseases.

Facial nerve transection causes expansion of myelin autoreactive T cells in regional lymph nodes and T cell homing to the facial nucleus

Nervous tissue expression of immunological signal and recognition molecules, as well as lymphoid tissue immune responses after facial nerve trauma was studied in male rats of the Lewis and Brown Norway (BN) strains. In both rat strains nerve transection caused within four days the appearance of IFN-gamma-like immunoreactivity in the cytoplasm of axotomized motor neurons and an induction of MHC class I and II, and CD4 molecules on surrounding glial cells to a similar extent. T lymphocytes also infiltrated the facial nuclei ipsilateral to the axotomy in all animals. The number of autoreactive T cells in superficial cervical lymph nodes, which in response to whole myelin or peptides of myelin basic protein (MBP) secreted IFN-gamma increased markedly after axotomy. This response was more conspicuous in Lewis rats, which are susceptible to experimental allergic encephalomyelitis (EAE), than in BN rats, which are EAE resistant. A proportion of the axotomized Lewis rats also developed widespread perivascular infiltration of mononuclear cells in the CNS, reminiscent of EAE. Hypothetically, a strong expansion of myelin autoreactive IFN-gamma producing T cells secondary to nerve trauma may have immunopathological consequences in genetically predisposed individuals. It is also possible that myelin reactive T cells, whether recruited to the lesioned nerve, could have impact on macrophage function during Wallerian degeneration in the distal stump.