Etanercept and demyelinating disease in a patient with psoriasis

Multifocal leukoencephalopathy in a patient medicated with etanercept and methotrexate for rheumatoid arthritis

Methotrexate (MTX) and etanercept are commonly used in the treatment of rheumatoid arthritis (RA). Several important adverse events, including central nervous system lesions, have been reported during RA treatment. Among them, MTX-induced leukoencephalopathy is a recognized complication that is often observed following intrathecal or intravenous MTX administration. Herein, we report a case of a RA patient who was diagnosed with multifocal leukoencephalopathy during etanercept and MTX therapy. A 77-year-old Chinese woman with a 3-year history of RA had been taking subcutaneous etanercept and low-dose oral MTX since February 2021. Five months after the initial administration, she developed cognitive impairment and experienced a dropped attack. She was then admitted to our hospital in June 2021. T2-weighted magnetic resonance imaging (MRI) images revealed disseminated lesions in the white matter of the brain. Based on these MRI findings and extensive clinical investigation that excluded other possible causes of white matter lesions, she was suspected of having a demyelinating disorder. There was no evidence suggesting other neurological disorders. High-dose corticosteroid was administered, which resulted in improved cognitive impairment. This case report illustrates an important example of multifocal leukoencephalopathy induced by the combined use of etanercept and MTX, which resolved with high-dose corticosteroid. With the recent emphasis on various biologic agents for treatment of RA, our case highlights the importance of identifying leukoencephalopathy that may be induced by various biologics.

Reverse causation between multiple sclerosis and psoriasis: a genetic correlation and Mendelian randomization study

Observational studies have found a potential bidirectional positive association between multiple sclerosis and psoriasis, but these studies are susceptible to confounding factors. We examined the directionality of causation using Mendelian randomization and estimated the genetic correlation using the linkage disequilibrium score. We performed Mendelian randomization analysis using large-scale genome-wide association studies datasets from the International Multiple Sclerosis Genetics Consortium (IMSGC, 115,803 individuals of European ancestry) and FinnGen (252,323 individuals of European ancestry). We selected several Mendelian randomization methods including causal analysis using summary effect (CAUSE), inverse variance-weighted (IVW), and pleiotropy-robust methods. According to CAUSE and IVW the genetic liability to MS reduces the risk of psoriasis (CAUSE odds ratio [OR] 0.93, p = 0.045; IVW OR 0.93, p = 2.51 × 10-20), and vice versa (CAUSE OR 0.72, p = 0.001; IVW OR 0.71, p = 4.80 × 10-26). Pleiotropy-robust methods show the same results, with all p-values < 0.05. The linkage disequilibrium score showed no genetic correlation between psoriasis and MS (rg =  - 0.071, p = 0.2852). In summary, there is genetic evidence that MS reduces the risk of psoriasis, and vice versa.

Therapeutic consequences in patients with both inflammatory rheumatic diseases and multiple sclerosis

Dealing with patients with both multiple sclerosis (MS) and inflammatory rheumatic disorders (IRDs) is not uncommon for a rheumatologist, as there is a statistical association between SpA and MS. As several CNS demyelinating events have been reported in patients treated with TNF inhibitor (TNFi), the pre-existing demyelinating disease was considered a contraindication for TNFi. However, this contraindication is mainly based on a randomized controlled trial in MS and not on large epidemiological studies. According to the last epidemiological studies, TNFi might not be an inducer of MS. Moreover, there are no clear recommendations on the use of the other DMARDs in patients suffering from an IRD and MS. In this review, we summarize the link between MS and IRDs and the impact of DMARDs on MS, especially TNFi. We also look at the impact of disease-modifying drugs for adults with MS and IRDs.

Biologic and Small-Molecule Therapies for Moderate-to-Severe Psoriasis: Focus on Psoriasis Comorbidities

Psoriasis is a systemic immune-mediated disease associated with an increased risk of comorbidities, such as psoriatic arthritis, cardiovascular disease, metabolic syndrome, inflammatory bowel disease, psychiatric disorders, and malignancy. In recent years, with the advent of biological agents, the efficacy and safety of psoriasis treatments have dramatically improved. Presently, tumor necrosis factor-α inhibitors, interleukin-17 inhibitors, interleukin-12/23 inhibitors, and interleukin-23 inhibitors are approved to treat moderate-to-severe psoriasis. Small-molecule inhibitors, such as apremilast and deucravacitinib, are also approved for the treatment of psoriasis. Although it is still unclear, systemic agents used to treat psoriasis also have a significant impact on its comorbidities by altering the systemic inflammatory state. Data from clinical trials and studies on the safety and efficacy of biologics and small-molecule inhibitors provide important information for the personalized care and treatment for patients with psoriasis. Notably, treatment with interleukin-17 inhibitors is associated with new-onset or exacerbations of inflammatory bowel disease. In addition, great caution needs to be taken when using tumor necrosis factor-α inhibitors in patients with psoriasis with concomitant congestive heart failure, multiple sclerosis, and malignancy. Apremilast may induce weight loss as an adverse effect, presenting also with some beneficial metabolic actions. A better understanding of the characteristics of biologics and small-molecule inhibitors in the treatment of psoriasis comorbidities can provide more definitive guidance for patients with distinct comorbidities.

Ixekizumab exposure associated with myelitis: A case report and a literature review

We describe a case of a 28-year-old man who developed a cervical myelitis while exposed to ixekizumab (IL-17 inhibitor) for psoriatic arthritis. Spinal MRI showed a T2 hyperintense lesion at the C4-C5 level while brain MRI was unspecific. Oligoclonal bands were absent and extensive screening for autoimmunity was negative. Rechallenge with ixekizumab was positive corroborating a relation between drug exposure and the neurological event. To the best of our knowledge, this is the first case of CNS inflammatory adverse event associated with ixekizumab. We also provide a review of case reports of demyelinating disorders associated with the use of biologic drugs for the treatment of psoriasis and psoriatic arthritis.

Infliximab-Associated Chronic Inflammatory Central Nervous System Disease and Peroneal Nerve Injury in a Psoriatic Patient Refractory to Treatment: Case Report with 10-Year Follow-Up

The tumor necrosis factor-α (TNF-α) antagonists infliximab, adalimumab, and etanercept have been approved for the treatment of chronic inflammatory diseases such as rheumatoid arthritis, ankylosing spondylitis, psoriasis, and psoriatic arthritis. Manifestations of demyelinating disease have been reported for patients receiving TNF-α antagonists. We describe a rare manifestation of a chronic inflammatory process affecting both the central and peripheral nervous system in a patient who received infliximab for the treatment of psoriasis and psoriatic arthritis. Infliximab therapy was discontinued and symptoms improved under high-dose intravenous glucocorticoid pulse therapy.

Review of IL-17 inhibitors for psoriasis

Background: The development of biologic agents directed against distinct cytokines and receptors has advanced the therapeutic options available for psoriasis patients. Evidence from preclinical studies suggests that IL-17 may contribute to the pathogenesis of psoriasis. Objective: The objective was to review the safety and efficacy profile for each IL-17 inhibitor by evaluating phase III clinical trial data. Methods: We reviewed the results of phase III clinical trials for the IL-17 inhibitors secukinumab, ixekizumab, and brodalumab. Results: At week 12, the proportion of patients reaching Psoriasis Area and Severity Index (PASI 75) was above 60% for the most efficacious dose of each agent with favorable and comparable safety profiles. The most commonly reported adverse events were nasopharyngitis, headache, and upper respiratory tract infection. Conclusions: The clinical improvement among psoriasis patients on IL-17 inhibitors is similar or superior to the improvement seen with commercially produced biologic agents available accompanied by a favorable short-term safety profile. The results of the phase III trials indicate that IL-17 inhibitors are effective therapeutic options for psoriasis patients.

Neurological and Neuropsychiatric Adverse Effects of Dermatologic Medications

Severe, recalcitrant dermatologic conditions often require systemic treatment. Although efficacious, these medications have been associated with wide-ranging adverse reactions. Some are reversible, predictable, and either dose-dependent or treatment length-dependent, while others are unpredictable, irreversible, and potentially fatal. This review examines the neuropsychiatric adverse effects associated with US FDA-approved medications for treatment of the following dermatologic pathologies that typically require systemic therapy: autoimmune dermatoses, acne, psoriasis, and melanoma. A search of the literature was performed, with adverse effects ranging from mild headaches and neuropathy to severe encephalopathies. The medications associated with the most serious reactions were those used to treat psoriasis, especially the older non-biologic medications such as cyclosporine A and methotrexate. Given the importance of these systemic dermatologic therapies in treating severe, recalcitrant conditions, and the wide variety of potentially serious neuropsychiatric adverse effects of these medications, neurologists, psychiatrists, dermatologists, oncologists, and primary care providers must be aware of the potential for these neuropsychiatric adverse reactions to allow for appropriate counseling, management, and medication withdrawal.

Side effects of TNF-α blockers in patients with psoriatic arthritis: evidences from literature studies

Psoriatic arthritis is an inflammatory rheumatic disorder, which occurs in patients with skin and/or nail psoriasis. In psoriatic arthritis, the importance of biologic mediators modulating inflammatory reaction, such as tumor necrosis factor, and the knowledge on their role in the pathogenesis of psoriatic arthritis influence the therapeutic choices. In the last years, the introduction of biologic drugs has greatly changed the treatment of psoriasis and psoriatic arthritis. In fact, tumor necrosis factor-α blockers demonstrated an effective action in the treatment of both skin and joint manifestations of psoriatic arthritis, but they have some adverse effects. The aim of this review is to revisit the literature data on adverse effects of tumor necrosis factor-α blockers in patients with psoriatic arthritis.

Demyelination during tumour necrosis factor antagonist therapy for psoriasis: a case report and review of the literature

Central nervous system (CNS) demyelination in a patient receiving tumour necrosis factor alpha (TNF-α) antagonist therapy in our practice prompted a search of the literature to assess the evidence for a causal relationship between TNF antagonist therapy and demyelination. We summarise clinical data extracted on 65 reported cases of CNS demyelination in patients receiving TNF antagonist therapy and show that the data are consistent with a drug-related aetiology given the temporal relationship between TNF antagonist initiation and symptoms, de-challenge-re-challenge phenomenon and the later age of disease onset compared with sporadic multiple sclerosis. Research on TNF signalling pathways also suggests a plausible causative role of TNF antagonist therapy in demyelination. However to date, controlled trial and pharmacovigilance data do not show an increased risk of demyelination in patients receiving TNF antagonist therapy. These data may be underpowered to exclude such a risk and pooled, collaborative data from multiple registries are warranted. Given the uncertainty in this area, clinicians should adhere to existing clinical guidance advising avoidance of TNF antagonist therapy in patients with a personal or family history of demyelination, and ensure all suitable patients are enrolled in long term safety registries in countries where these are established.

Inflammatory neurological disease in patients treated with tumor necrosis factor alpha inhibitors

Background: TNF alpha inhibitor (TNFAI) therapy has been associated with inflammatory neurological syndromes.

Objectives: To present 10 new cases of TNFAI associated neurological disease and a review of the literature.

Methods: The design and methods were based on case series collected from Oregon Health & Sciences University and the Department of Veterans Affairs Hospital in Portland, Oregon and PubMed review.

Results: We describe eight demyelinating central nervous system syndromes and two peripheral nervous system syndromes associated with TNFAI therapy. Characteristics from these cases are analyzed with data from 141 additional cases from the literature. Onset was between the ages of 36 and 65 years in 84% of CNS cases, distinguishing TNFAI-associated disease from sporadic multiple sclerosis. Symptoms occurred within one year of TNFAI therapy in 71%. Etanercept therapy was reported in the majority of cases of CNS syndromes and infliximab therapy in the majority of neuromuscular syndromes. Significant disability remained in 67% of cases although 82% had been followed for less than one year.

Conclusions: Our case series and literature review demonstrates an association between TNFAI therapy and inflammatory neurological disease. While a causal relationship is suggested, this remains uncertain. TNFAI-associated neurological syndromes are associated with significant disability and longer follow-up is needed to better determine natural history and evaluate appropriate treatment interventions.

The safety of etanercept for the treatment of plaque psoriasis

Effective treatment with etanercept results from a congregation of immunological signaling and modulating roles played by tumor necrosis factor-alpha (TNF-alpha), a pervasive member of the TNF super-family of cytokines participating in numerous immunologic and metabolic functions. Macrophages, lymphocytes and other cells produce TNF as part of the deregulated immune response resulting in psoriasis or other chronic inflammatory disorders. Tumor necrosis factor is also produced by macrophages and lymphocytes responding to foreign antigens as a primary response to potential infection. Interference with cytokine signaling by etanercept yields therapeutic response. At the same time, interference with cytokine signaling by etanercept exposes patients to potential adverse events. While the efficacy of etanercept for the treatment of psoriasis is evident, the risks of treatment continue to be defined. Of the potential serious adverse events, response to infection is the best characterized in terms of physiology, incidence, and management. Rare but serious events: activation of latent tuberculosis, multiple sclerosis, lymphoma, and others, have been observed but have questionable or yet to be defined association with therapeutic uses of etanercept. The safe use of etanercept for the treatment of psoriasis requires an appreciation of potential adverse events as well as screening and monitoring strategies designed to manage patient risk

The complex world of oligodendroglial differentiation inhibitors

Myelination is a central nervous system (CNS) process wherein oligodendrocyte-axon interactions lead to the establishment of myelin sheaths that stabilize, protect, and electrically insulate axons. In inflammatory demyelinating diseases such as multiple sclerosis (MS), the degeneration and eventual loss of functional myelin sheaths slows and blocks saltatory conduction in axons, which results in clinical impairment. However, remyelination can occur, and lesions can be partially repaired, resulting in clinical remission. The recruitment and activation of resident oligodendrocyte precursor cells (OPCs) play a critical role in the repair process because these cells have the capacity to differentiate into functional myelinating cells. Mature oligodendrocytes, however, are thought to have lost the capacity to develop new myelin sheaths and frequently undergo programmed cell death in MS. The endogenous capacity to generate new oligodendrocytes in MS is limited, and this is predominantly due to the presence of inhibitory components that block OPC differentiation and maturation. Here, we present an overview of recently identified negative regulators of oligodendroglial differentiation and their potential relevance for CNS repair in MS. Because currently available immunomodulatory drugs for MS mainly target inflammatory cascades outside the brain and fail to repair existing lesions, achieving more efficient lesion repair constitutes an important goal for future MS therapies.

Psoriasis and Multiple Sclerosis: Is There a Link?

Background:

Psoriasis and multiple sclerosis (MS) are both autoimmune T cell-mediated diseases. Some case series have suggested an association.

Objective:

To investigate the potential relationship between psoriasis and MS based on a systematic review of the literature.

Methods:

Medline, Cochrane Library, and EMBASE searches were performed.

Results:

T-helper 17 cells are involved in the pathogenesis of both psoriasis and MS. Both conditions have been associated with interleukin-23 receptor (IL23R) polymorphisms. Studies have reported psoriasis in 0.41 to 7.7% of individuals with MS. A higher rate of psoriasis compared to controls was noted in a few small MS cohorts, but the number of cases was too small to draw any firm conclusions. In two studies, including a large Canadian study of 5,031 patients with MS, there was no increased prevalence of psoriasis in patients over the control population. Family members of individuals with MS do not appear to be at increased risk for psoriasis in these studies. Psoriasis has developed during treatment for MS, and MS has developed during treatment for psoriasis.

Conclusion:

Although there are some common genetic linkages in psoriasis and MS, psoriasis does not appear to be more common in patients with MS or their relatives.

Neurological adverse events associated with anti-tumor necrosis factor α treatment

Anti-tumor necrosis factor alpha (TNF-alpha) drugs have been successfully used for the treatment of rheumatic autoimmune diseases including rheumatoid arthritis (RA), psoriatic arthritis, psoriasis, ankylosing spondylitis (AS), juvenile chronic arthritis, and Crohn's disease. However, they have been associated with different neurological disorders, including alterations of peripheral nerves, multiple sclerosis (MS), optic neuritis (ON) and acute transverse myelitis (ATM). This article reviews the most current aspect regarding neurological adverse events associated with anti-TNF-alpha drugs with emphasis on the possible explanations for this relation and the pathogenic mechanism of TNF-alpha in neurological disorders.

Psoriasis during interferon beta treatment for multiple sclerosis

Previous reports have suggested an increased risk of psoriasis in MS patients. Worsening of dermatologic lesions during interferon therapy has been rarely reported, but activation of psoriatic arthritis has not been described until now. The following is a case report. A 37-year-old woman affected by relapsing-remitting multiple sclerosis had severe worsening of cutaneous psoriasis and activation of psoriatic arthritis during interferon beta treatment. The symptoms resolved after therapy discontinuation. This case further supports that activation of psoriasis might be a rare side effect of IFNB therapy and suggests careful evaluation of concomitant morbidity to allow a patient-oriented treatment strategy.

A case of rheumatoid arthritis complicated by demyelination in both cerebral cortex and spinal cord during etanercept therapy

Tumor necrosis factor (TNF) antagonists, including etanercept, have been approved for the treatment of rheumatoid arthritis (RA). These agents are not free of adverse events like other antirheumatic agents. Several important adverse events in CNS lesions have been reported. In this paper, we report on one patient with RA that had complications from a demyelinating disorder during TNF-blockade therapy using etanercept at 24 months after initial administration. A 66-year-old Japanese woman was diagnosed with RA in 1959. She received various disease-modifying antirheumatic drugs (DMARDs), but all of these agents were ineffective. She was administered etanercept in June 2005, and stayed well. Twenty-four months after the initial administration of etanercept, she developed palsy of bilateral upper extremities and gait disturbance subacutely, and was then admitted to our institute in August 2007. MRI of her spinal cord revealed a high-intensity lesion from the third through to the seventh cervical (C3-C7) levels. Additionally, T2-weighted MRI images showed disseminated high-intensity lesions in the white matter of brain. She was suspected of having a demyelinating disorder based on these MRI findings. There was no significant finding that pointed to another neurological disorder. High-dose corticosteroid therapy was conducted and was effective for her.

Central nervous system demyelination associated with etanercept in a 51 years old woman

There are few case reports documenting a new onset of demyelinating processes in patients receiving anti-tumour necrosis factor alpha therapy (anti-TNF alpha) for chronic inflammatory arthropathies. Whether anti-TNF alpha therapy induces new onset demyelination or just exacerbates pre-existing latent multiple sclerosis is not fully understood. We are reporting a 51-year-old woman without a prior history of multiple sclerosis, who developed demyelinating brain lesions three months after starting Etanercept. Her symptoms partially resolved on cessation of the drug. Our case was unusual compared to some previous case reports, as the patient's age at presentation was beyond that for idiopathic multiple sclerosis. This may strengthen the hypothesis of a causal relationship between new onset demyelination and Etanercept; however, exacerbation of pre-existing demyelinating process by Etanercept in this patient still cannot be totally excluded. We recommend doing magnetic resonance imaging (MRI) of the brain before starting patients on anti-TNF alpha therapy to exclude latent demyelination. In addition, new onset demyelination following anti-TNF alpha therapy should be reported and studied thoroughly as this may yield a significant advancement in our understanding of the pathogenesis of multiple sclerosis. Long-term follow-up of these cases is also important to determine the long-term prognosis and the rate of relapse of demyelinating process in this group of patients.

Problems encountered during anti-tumour necrosis factor therapy

Worldwide, over 400,000 patients have been treated with tumour necrosis factor (TNF)-alpha antagonists for indications that include rheumatoid arthritis, juvenile rheumatoid arthritis, inflammatory bowel disease, psoriatic arthritis and ankylosing spondylitis. Since their approval, concerns regarding safety have been raised. There is a risk of re-activation of granulomatous diseases, especially tuberculosis, and measures should be taken for detection and treatment of latent tuberculosis infections. Preliminary data suggest that anti-TNF therapy may be safe in chronic hepatitis C. However, TNF-alpha antagonists have resulted in re-activation of chronic hepatitis B if not given concurrently with antiviral therapy. Solid tumours do not appear to be increased with anti-TNF therapy. Variable rates of increased lymphoma risk have been described with anti-TNF therapy compared with the general population, although no increased risk was found compared with a rheumatoid arthritis population. Large phase II and III trials with TNF-alpha antagonists in advanced heart failure have shown trends towards a worse prognosis, and should therefore be avoided in this population. Both etanercept and infliximab are associated with the formation of autoantibodies, and these autoantibodies are rarely associated with any specific clinical syndrome. Rare cases of aplastic anaemia, pancytopenia, vasculitis and demyelination have been described with anti-TNF therapy. This chapter will discuss the safety profile and adverse events of the three commercially available TNF-alpha antagonists: etanercept, infliximab and adalimumab. The data presented in this review have been collected from published data, individual case reports or series, package inserts, the Food and Drug Administration postmarketing adverse events surveillance system, and abstracts from the American College of Rheumatology and European Congress of Rheumatology meetings for 2005.

Risk???:???Benefit Profile of Etanercept in??Elderly Patients with Rheumatoid Arthritis, Ankylosing Spondylitis or??Psoriatic Arthritis

Rheumatoid arthritis (RA), ankylosing spondylitis (AS) and psoriatic arthritis (PsA) are commonly thought of as inflammatory diseases that affect younger individuals. Although the initial presentation of these diseases is commonly in a patient's twenties or thirties, they usually persist for the duration of the patient's life. In addition, up to one-third of patients with RA have disease onset after 60 years of age. Older patients with any of these three diseases are more likely to have more severe disease with significant functional decline. They are also more likely to have co-morbid diseases and use concomitant medications than patients who are younger. In patients with RA, AS or PsA, the introduction of anti-tumour necrosis factor (TNF)-alpha therapies such as etanercept, infliximab and adalimumab has had a significant impact in ameliorating the signs and symptoms of disease, improving patient function and inhibiting radiographic progression. Anti-TNFalpha therapies now have well recognised safety profiles that have been demonstrated in the usual clinical trial populations for these diseases, but such populations under-represent patients > or =65 years of age. This review explores the information currently available regarding patients aged > or =65 years treated with anti-TNFalpha therapies for RA, AS or PsA, focusing on etanercept in RA because of a lack of data for other therapies and conditions. The analyses conducted show that there is similar efficacy in the treatment of RA in patients <65 years old and those > or =65 years of age. Although there are some differences in the adverse events noted in these two age groups, it appears as though treatment of patients > or =65 years of age, compared with age-matched controls, is not dissimilar to treatment of patients <65 years of age compared with their age-matched controls. Only by understanding the risks and benefits of therapy in the older age group can a true risk : benefit profile for etanercept, and ultimately other anti-TNFalpha therapies, be determined by the practising physician and the patient.

Safety of etanercept in psoriasis: a critical review

Conventional systemic treatments for patients with psoriasis are associated with multiple adverse effects that require continuous monitoring. The introduction of new biological agents such as etanercept, a fully human fusion protein, has permitted individualisation of patients' treatment according to disease stage. The drug is a competitive inhibitor of tumour necrosis factor-alpha (TNFalpha) that prevents interaction between this cytokine and its cell surface receptors. Etanercept also modulates the activity of other inflammatory cytokines and does not induce complement-mediated cell lysis in vitro. The main source of information regarding etanercept safety comes from studies in patients with rheumatoid arthritis. The most common adverse effect during drug administration is mild injection site reactions. There is no increase in the overall incidence of infections compared with placebo, although there have been several reports of infections caused by intracellular organisms (Mycobacterium tuberculosis, Listeria monocytogenes, and Mycobacterium avium intracellulare). Therefore, combination of this drug with corticosteroids must be carefully monitored and should be avoided in patients with established sepsis. There are no data showing that treatment with etanercept results in an increase in the occurrence of malignant neoplasms. However, caution is recommended in use of etanercept in patients with a current or past history of demyelinating disease. Etanercept must be used with extreme caution in patients with heart failure because of several reports indicating a worsening or de novo occurrence of congestive heart failure while receiving the drug. Monitoring of autoantibodies is not currently considered necessary as they do not predict response, toxicity or autoimmune events. The presence of non-neutralising antibodies to the TNF receptor fragment or other protein components of etanercept has not been related to a decrease in drug response or adverse reactions. Etanercept does not generally modify the course of inflammatory bowel disease. When combined with other systemic therapies for psoriasis, current data do not show an increase in adverse events. In patients with hepatitis C viral infection, etanercept does not increase transaminase levels or viral load and in some instances has allowed the concomitant use of interferon which had previously been discontinued because of a worsening of psoriasis. Etanercept is rated as a US FDA category B drug in pregnancy. However, its use is not recommended in pregnant women unless the benefit-risk ratio greatly favours its use. Etanercept is not recommended for use in lactating women. Etanercept represents a relevant treatment for psoriasis, efficacious over many weeks and safe but special care should be taken to avoid the potential risks.

Blocking soluble tumor necrosis factor signaling with dominant-negative tumor necrosis factor inhibitor attenuates loss of dopaminergic neurons in models of Parkinson's disease

The mechanisms that trigger or contribute to loss of dopaminergic (DA) neurons in Parkinson's disease (PD) remain unclear and controversial. Elevated levels of tumor necrosis factor (TNF) in CSF and postmortem brains of PD patients and animal models of PD implicate this proinflammatory cytokine in the pathophysiology of the disease; but a role for TNF in mediating loss of DA neurons in PD has not been clearly demonstrated. Here, we report that neutralization of soluble TNF (solTNF) in vivo with the engineered dominant-negative TNF compound XENP345 (a PEGylated version of the TNF variant A145R/I97T) reduced by 50% the retrograde nigral degeneration induced by a striatal injection of the oxidative neurotoxin 6-hydroxydopamine (6-OHDA). XENP345 was neuroprotective only when infused into the nigra, not the striatum. XENP345/6-OHDA rats displayed attenuated amphetamine-induced rotational behavior, indicating preservation of striatal dopamine levels. Similar protective effects were observed with chronic in vivo coinfusion of XENP345 with bacterial lipopolysaccharide (LPS) into the substantia nigra, confirming a role for solTNF-dependent neuroinflammation in nigral degeneration. In embryonic rat midbrain neuron/glia cell cultures exposed to LPS, even delayed administration of XENP345 prevented selective degeneration of DA neurons despite sustained microglia activation and secretion of solTNF. XENP345 also attenuated 6-OHDA-induced DA neuron toxicity in vitro. Collectively, our data demonstrate a role for TNF in vitro and in vivo in two models of PD, and raise the possibility that delaying the progressive degeneration of the nigrostriatal pathway in humans is therapeutically feasible with agents capable of blocking solTNF in early stages of PD.