Demyelination as a complication of new immunomodulatory treatments

Drug-related immune-mediated myelopathies

Iatrogenic immune-mediated inflammatory disorders of the spinal cord are an uncommon but potentially severe complication of drug therapy for several human diseases. Particularly the introduction of novel biological agents in the treatment of systemic inflammatory disorders and cancer immunotherapy have led to a significant increase in immune-related adverse events of the central nervous system (CNS). The use of Tumor necrosis factor alpha (TNF-alpha) inhibitors in rheumatic and inflammatory bowel diseases has been associated with demyelinating and other inflammatory CNS conditions, including myelitis. The introduction of immune checkpoint inhibitors in the treatment of several human malignancies has led to an increase in drug-induced immune-related adverse events including in the CNS. Other drugs that have been associated with immune-mediated myelitis include tyrosine-kinase inhibitors and chimeric antigen receptor (CAR) T Cell therapy. A high degree of suspicion is necessary when diagnosing these conditions, as early diagnosis and treatment is crucial in preventing further neurological damage and disability. The treatment of drug-induced inflammatory myelitis typically involves administration of high-dose intravenous corticosteroids, however additional immunosuppressive agents may be required in severe or refractory cases. While most cases are monophasic and remit following discontinuation of the offending agent, chronic immunosuppressive therapy may be indicated in cases with a progressive or relapsing disease course or when a diagnosis of a specific underlying neuro-inflammatory disorder is made. Outcomes are generally favorable, however depend on the specific therapeutic agent used, the clinical presentation and patient factors. In this review we aim to describe the clinical characteristics, imaging findings and management for the most common forms of iatrogenic immune-mediated myelopathies.

Prevalence of iatrogenic CNS inflammation at a tertiary neuroimmunology clinic

BACKGROUND

Various vaccines, tumor-necrosis-factor-alpha inhibitors (TNFAIs), immune-checkpoint inhibitors (ICIs), and other immunomodulators have been linked to inflammatory CNS events. The prevalence of iatrogenic events in the neuroimmunology clinic is unknown.

OBJECTIVE

To evaluate the prevalence and clinical characteristics of iatrogenic CNS inflammation in a tertiary neuroimmunology clinic.

METHODS

We analyzed 422 consecutive patients seen over five years at a tertiary neuroimmunology clinic who were systematically screened for exposure to vaccines, TNFAIs, ICIs, or other immunomodulators. In patients with suspected iatrogenic events, the Naranjo Adverse Drug Reaction Probability Scale was used to score the probability of iatrogenicity.

RESULTS

In total, 27 potential iatrogenic events were observed, accounting for 6.4% of all new referrals. The average Naranjo score was 5.78 +/- 1.65 with 74% of the cases scored as probable and 26% scored as possible. The clinical phenotypes included MS relapses (37%); autoimmune encephalitis (30%); NMOSD attacks (15%); transverse myelitis (11%); optic neuritis (4%); and MOGAD attacks (4%). A monophasic course was observed in 44% of cases while 41% had a relapsing course. All patients stopped or interrupted treatment with the offending agent. In addition, 41% of the iatrogenic events were fully responsive to corticosteroids; 22% were partially responsive; and 15% resolved spontaneously. The most common potential triggers were vaccines (37%) followed by TNFAIs (33%) then ICIs (26%). A significantly higher number of probable iatrogenic events were observed among the ICI and vaccine groups compared to a higher number of possible events among the TNFAI group. The latter group also had a significantly longer interval since exposure. The ICI group was more likely to present with monophasic autoimmune encephalitis.

CONCLUSION

Iatrogenic CNS inflammation is rare and typically involves steroid-responsive monophasic events. A subset of iatrogenic events can unmask or worsen relapsing disorders. The probability of iatrogenicity was higher in vaccine and ICI-related events compared to TNFAI-related events.

Iatrogenic CNS demyelination in the era of modern biologics

The number of reported cases of iatrogenic demyelination of the central nervous system (CNS) is on the rise. This is, in part, related to the recent expansion in the use of biologics. Review of literature from the past decade suggests that in addition to vaccines, tumor necrosis factor (TNF)-alpha inhibitors and checkpoint inhibitors are the most frequently cited inducers of central inflammation. About one-third of demyelinating cases in the setting of TNF-alpha inhibitors evolve into full-blown multiple sclerosis. In addition to demyelination, checkpoint inhibitors may also cause accelerated paraneoplastic encephalitis and other antibody-mediated conditions. Luckily, the overall prognosis of iatrogenic central inflammation is favorable, with most cases having partial or complete response to steroids and discontinuation of the offending agent. Long-term monitoring and initiation of maintenance immune-modulating therapy may be necessary in some patients. In this article, we provide an updated review of biologic-induced inflammation of the CNS.

Impaired T-cell migration to the CNS under fingolimod and dimethyl fumarate

Objective:

To evaluate the long-term effects of treatments used in MS on the T-cell trafficking profile.

Methods:

We enrolled 83 patients with MS under fingolimod (FTY), natalizumab (NTZ), dimethyl fumarate (DMF), or other disease-modifying treatments (DMTs). Blood was drawn before treatment onset and up to 36–48 months. The ex vivo expression of CNS-related integrins (α4β1 and α_L subunit of LFA-1) and the gut-related integrin (α4β7) was assessed using flow cytometry on CD4⁺ and CD8⁺ T cells. The adhesion profiles of CD3⁺ T cells to specific integrin ligands (vascular cell adhesion molecule-1 [VCAM-1], intercellular adhesion molecule-1 [ICAM-1], and mucosal vascular addressin cell adhesion molecule-1 [MAdCAM-1]) were measured in vitro before and after 12 and 36–48 months.

Results:

NTZ decreased the frequency of α4β1⁺ and α4β7⁺ integrin expressing T cells and the binding of these cells to VCAM-1 and MAdCAM-1, respectively. After 12 months, DMF induced a decreased frequency of α_L^highCD4⁺ T cells combined with reduced binding to ICAM-1. By contrast, with FTY, there was a doubling of the frequency of α4β1⁺ and α_L^high, but a decreased frequency of α4β7⁺ T cells. Strikingly, the binding of α4β1⁺, α4β7⁺, and to a lesser extent of α_L^high T cells to VCAM-1, MAdCAM-1, and ICAM-1, respectively, was decreased at month 12 under FTY treatment. The presence of manganese partially restored the binding of these T cells to VCAM-1 in vitro, suggesting that FTY interferes with integrin activation.

Conclusions:

In addition to NTZ, DMF and FTY but not other tested DMTs may also decrease T-cell–mediated immune surveillance of the CNS. Whether this mechanism may contribute to the onset of CNS opportunistic infections remains to be shown.

N-Terminally extended analogues of the K⁺ channel toxin from Stichodactyla helianthus as potent and selective blockers of the voltage-gated potassium channel Kv1.3

The voltage-gated potassium channel Kv1.3 is an important target for the treatment of autoimmune diseases and asthma. Blockade of Kv1.3 by the sea anemone peptide K⁺-channel toxin from Stichodactyla helianthus (ShK) inhibits the proliferation of effector memory T lymphocytes and ameliorates autoimmune diseases in animal models. However, the lack of selectivity of ShK for Kv1.3 over the Kv1.1 subtype has driven a search for Kv1.3-selective analogues. In the present study, we describe N-terminally extended analogues of ShK that contain a negatively-charged Glu, designed to mimic the phosphonate adduct in earlier Kv1.3-selective analogues, and consist entirely of common protein amino acids. Molecular dynamics simulations indicated that a Trp residue at position [-3] of the tetrapeptide extension could form stable interactions with Pro377 of Kv1.3 and best discriminates between Kv1.3 and Kv1.1. This led to the development of ShK with an N-terminal Glu-Trp-Ser-Ser extension ([EWSS]ShK), which inhibits Kv1.3 with an IC₅₀ of 34 pm and is 158-fold selective for Kv1.3 over Kv1.1. In addition, [EWSS]ShK is more than 2900-fold more selective for Kv1.3 over Kv1.2 and KCa3.1 channels. As a highly Kv1.3-selective analogue of ShK based entirely on protein amino acids, which can be produced by recombinant expression, this peptide is a valuable addition to the complement of therapeutic candidates for the treatment of autoimmune diseases.

Immunogenicity and other problems associated with the use of biopharmaceuticals

Biopharmaceuticals are used widely for the treatment of cancer, chronic viral hepatitis, inflammatory, and autoimmune diseases. Biopharmaceuticals such as interferons are well tolerated for the most part with the most common adverse events observed being 'flu-like' symptoms that resolve rapidly after initial treatment. Prolonged treatment is associated, however, with more serious adverse events including leucopenia, thrombocytopenia, and neuropsychiatric effects, which may necessitate dose reduction or even cessation of treatment in some patients. Recombinant growth factors, such as erythropoietin (EPO), granulocyte colony-stimulating factor, or granulocyte macrophage colony-stimulating factor, are for the most part well tolerated, although severe complications have been reported in patients with cancer or chronic kidney disease treated with EPO. Similarly, treatment of patients with cancer with high doses of interleukin-2 is associated with significant toxicity. Treatment of chronic inflammatory diseases, such as rheumatoid arthritis, psoriasis, and Crohn's disease, with antitumor necrosis factor-alpha monoclonal antibodies is associated with an increased risk of granulomatous infections and, in particular, tuberculosis. The monoclonal antibody, natalizumab, that targets alpha4 integrins is effective in the treatment of multiple sclerosis but is associated with the activation of JC virus and development of progressive multifocal leukoencephalopathy. Repeated administration of recombinant proteins can cause a break in immune tolerance in some patients resulting in the production of a polyclonal antibody response that can adversely affect pharmacokinetics and clinical response. In addition, neutralizing antibodies that cross react with nonredundant essential proteins such as EPO can cause severe autoimmune reactions.

Critical role of DNA methylation in the pathogenesis of systemic lupus erythematosus: new advances and future challenges

Systemic lupus erythematosus (SLE) is a systemic multi-organ autoimmune disease with different immunological characteristics and clinical manifestations characterized by an autoantibody response to nuclear and cytoplasmic antigens; the etiology of this disease remains largely unknown. Most recent genome-wide association studies demonstrate that genetics significantly predispose to SLE onset, but the incomplete disease concordance rates between monozygotic twins indicates a role for other complementary factors in SLE pathogenesis. Recently, much evidence strongly supports other molecular mechanisms involved in the regulation of gene expression ultimately causing autoimmune disease, and several studies, both in clinical settings and experimental models, have demonstrated that epigenetic modifications may hold the key to a better understanding of SLE initiation and development. DNA methylation changes the structure of chromatin, being typically able to modulate the fine interactions between promoter-transcription factors and encoding genes within the transcription machinery. Alteration in DNA methylation has been confirmed as a major epigenetic mechanism that may potentially cause a breakdown of immune tolerance and perpetuation of SLE. Based on recent findings, DNA methylation treatments already being used in oncology may soon prove beneficial to patients with SLE. We herein discuss what we currently know, and what we expect in the future.

Human polyomavirus JC reactivation and pathogenetic mechanisms of progressive multifocal leukoencephalopathy and cancer in the era of monoclonal antibody therapies

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system caused by the neurotropic human polyomavirus JC (JCV) lytic infection of oligodendrocytes. PML was first described as a complication of lymphoproliferative disorders more than 50 years ago and emerged as a major complication of human immunodeficiency virus (HIV) infection in the 1980s. Despite the ubiquity of this virus, PML is rare and always seen in association with underlying immunosuppressive condition, such as HIV infection, autoimmune diseases, cancer, and organ transplantation. JCV remains quiescent in the kidneys, where it displays a stable archetypal non-coding control region (NCCR). Conversely, rearranged JCV NCCR, including tandem repeat patterns found in the brain of PML patients, have been associated with neurovirulence. The specific site and mechanism of JCV NCCR transformation is unknown. According to one model, during the course of immunosuppression, JCV departs from its latent state and after entering the brain, productively infects and destroys oligodendrocytes. Although the majority of PML cases occur in severely immunesuppressed individuals, PML has been increasingly diagnosed in patients treated with biological therapies such as monoclonal antibodies (mAbs) that modulate immune system functions: in fact, CD4+ and CD8+ T lymphopenia, resulting from this immunomodulatory therapy, are the primary risk factor. Furthermore, JCV reactivation in nonpermissive cells after treatment with mAbs, such as intestinal epithelial cells in Crohn's disease patients, in association with other host tumor-inducing factors, could provide valid information on the role of JCV in several malignancies, such as colorectal cancer.

New insights on human polyomavirus JC and pathogenesis of progressive multifocal leukoencephalopathy

John Cunningham virus (JCV) is a member of the Polyomaviridae family. It was first isolated from the brain of a patient with Hodgkin disease in 1971, and since then the etiological agent of the progressive multifocal leukoencephalopathy (PML) was considered. Until the human immunodeficiency virus (HIV) pandemic, PML was rare: in fact HIV-induced immunodeficiency is the most common predisposing factor accounting for 85% of all instances of PML. This data led to intense research on JCV infection and resulted in better understanding of epidemiology and clinic-pathologic spectrum. Recently, cases of PML have been observed after the introduction of monoclonal antibodies, such as natalizumab, rituximab, efalizumab, and infliximab, in the treatment of autoimmune disease, underlining the important role of host immunity in PML pathogenesis. In this review current understanding of the JCV infection and the new findings relating to the pathogenesis of PML has been comprehensively revised, focusing our attention on the interaction between the cellular and viral molecular pathways implicated in the JCV infection and the modulating role of host immune surveillance in the viral reactivation from a latent state.

Treat-to-target: a tailored treatment approach to rheumatoid arthritis

In contrast to articles and books written about rheumatoid arthritis (RA) two or more decades ago that largely focused on 'coping' with the disease, there have been significant developments in the treatment of RA over the past 10 years. Patients can now be diagnosed and treated and expect to live functional lives, with less likelihood of experiencing the associated joint damage and disability. An important goal of RA therapy has shifted to initiate treatment early and aggressively, with frequent assessment and a target to achieve remission as quickly as possible. This 'treat-to-target' concept has been endorsed to maximise long-term health-related quality of life through control of symptoms, prevention of structural damage, normalisation of function and social participation. This article will look at therapies and strategies for the treatment of RA. It will also discuss a treatment algorithm for rheumatoid arthritis tailored to the individual patient's disease activity status.

Bendamustine Associated with Irreversible Ascending Paralysis

Bendamustine is an alkylating agent currently used in the treatment of lymphoproliferative disorders. Many adverse effects, including a rare case of reversible neurotoxicity, have been reported in association with bendamustine. Herein, we report the first case of irreversible ascending paralysis related to bendamustine.

Systematic review: managing suboptimal treatment responses in autoimmune hepatitis with conventional and nonstandard drugs

BACKGROUND

Corticosteroid treatment for autoimmune hepatitis has been shown by randomised controlled clinical trials to ameliorate symptoms, normalise liver tests, improve histological findings and extend survival. Nevertheless, suboptimal responses to corticosteroid treatment still occur.

AIM

To describe the current definitions, frequencies, clinical relevance and treatment options for suboptimal responses, and to discuss alternative medications that have been used off-label for these occurrences.

METHODS

Literature search was made for full-text papers published in English using the keyword 'autoimmune hepatitis'. Authors' personal experience and investigational studies also helped to identify important contributions to the literature.

RESULTS

Suboptimal responses to standard therapy include treatment failure (7%), incomplete response (14%), drug toxicity (13%) and relapse after drug withdrawal (50-86%). The probability of a suboptimal response prior to treatment is higher in young patients and in patients with a severe presentation, jaundice, high MELD score at diagnosis, multilobular necrosis or cirrhosis, antibodies to soluble liver antigen, or inability to improve by clinical indices within two weeks or by MELD score within 7 days of conventional corticosteroid treatment. Management strategies have been developed for the adverse responses and nonstandard drugs, including mycophenolate mofetil, budesonide, ciclosporin, tacrolimus, sirolimus and rituximab, are emerging as rescue therapies or alternative frontline agents.

CONCLUSIONS

Once diagnosed, the suboptimal response should be treated by a highly individualised and well-monitored regimen, preferentially using first-line therapy. Nonstandard drugs warrant consideration as salvage or second-line therapies.

Ibudilast, a pharmacologic phosphodiesterase inhibitor, prevents human immunodeficiency virus-1 Tat-mediated activation of microglial cells

Human Immunodeficiency Virus-1 (HIV-1)-associated neurocognitive disorders (HAND) occur, in part, due to the inflammatory response to viral proteins, such as the HIV-1 transactivator of transcription (Tat), in the central nervous system (CNS). Given the need for novel adjunctive therapies for HAND, we hypothesized that ibudilast would inhibit Tat-induced excess production of pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNFα) in microglial cells. Ibudilast is a non-selective cyclic AMP phosphodiesterase inhibitor that has recently shown promise as a treatment for neuropathic pain via its ability to attenuate glial cell activation. Accordingly, here we demonstrate that pre-treatment of both human and mouse microglial cells with increasing doses of ibudilast inhibited Tat-induced synthesis of TNFα by microglial cells in a manner dependent on serine/threonine protein phosphatase activity. Ibudilast had no effect on Tat-induced p38 MAP kinase activation, and blockade of adenosine A_2A receptor activation did not reverse ibudilast's inhibition of Tat-induced TNFα production. Interestingly, ibudilast reduced Tat-mediated transcription of TNFα, via modulation of nuclear factor-kappa B (NF-κB) signaling, as shown by transcriptional activity of NF-κB and analysis of inhibitor of kappa B alpha (IκBα) stability. Together, our findings shed light on the mechanism of ibudilast's inhibition of Tat-induced TNFα production in microglial cells and may implicate ibudilast as a potential novel adjunctive therapy for the management of HAND.