Rapid improvement in verbal fluency and aphasia following perispinal etanercept in Alzheimer's disease

Perispinal etanercept stroke trial design: PESTO and beyond

INTRODUCTION

Perispinal etanercept (PSE) is an innovative treatment designed to improve stroke recovery by addressing chronic post-stroke neuroinflammation. Basic science evidence, randomized clinical trial (RCT) evidence and 14 years of favorable clinical experience support the use of PSE to treat chronic stroke. This article provides guidance for the design of future PSE RCTs in accordance with current FDA recommendations.

AREAS COVERED

Scientific background and essential elements of PSE RCT design.

EXPERT OPINION

Intimate familiarity with PSE, its novel method of drug delivery, and the characteristics of ideal enriched study populations are necessary for those designing future PSE stroke trials. The design elements needed to enable a PSE RCT to generate valid results include a suitable research question; a homogeneous study population selected using a prospective enrichment strategy; a primary outcome measure responsive to the neurological improvements that result from PSE; trialists with expertise in perispinal delivery; optimal etanercept dosing; and steps taken to minimize the number of placebo responders. RCTs failing to incorporate these elements, such as the PESTO trial, are incapable of reaching reliable conclusions regarding PSE efficacy. SF-36 has not been validated in PSE trials and is unsuitable for use as a primary outcome measure in PSE RCTs.

Association between disease-modifying antirheumatic drugs for rheumatoid arthritis and risk of incident dementia: a systematic review with meta-analysis

BACKGROUND

Dysregulation of several inflammatory cytokines including tumour necrosis factor (TNF) in dementia patients has also been identified as a key factor in the pathogenesis of rheumatoid arthritis (RA). We aimed to investigate the association of disease-modifying antirheumatic drugs (DMARDs) therapy for RA with risk of incident dementia.

METHODS

Electronic database searches of PubMed, EMBASE and Cochrane Library were performed. Observational studies that assessed the association of dementia with DMARDs in RA were included. Pooled risk ratios (RRs) with 95% CIs were used as summary statistic. The certainty of evidence was judged by using the Grading of Recommendations Assessment, Development and Evaluation system.

RESULTS

Overall, 14 studies involving 940 442 patients with RA were included. Pooled RR for developing dementia was 0.76 (95% CI 0.72 to 0.80) in patients taking biological DMARDs overall versus those taking conventional synthetic DMARDs, with 24% for TNF inhibitors (RR 0.76, 95% CI 0.71 to 0.82), 24% for non-TNF biologics (RR 0.76, 95% CI 0.70 to 0.83), separately. There was a significant subgroup effect among different types of TNF inhibitors (RR 0.58 [95%CI 0.53 to 0.65], 0.65 [95% CI 0.59 to 0.72], 0.80 [95% CI 0.72 to 0.88] for etanercept, adalimumab, infliximab, respectively; p value between groups=0.002). However, compared with non-users of DMARDs or investigative treatment, no significant effect on dementia incidence was observed in those receiving conventional synthetic DMARDs overall (RR 0.84, 95% CI 0.59 to 1.20), methotrexate (RR 0.78, 95% CI 0.54 to 1.12), hydroxychloroquine (RR 0.95, 95% CI 0.63 to 1.44), except for sulfasalazine (RR 1.27, 95% CI 1.06 to 1.50).

CONCLUSIONS

Biological DMARDs for RA are associated with decreased dementia risk, while protective effect is not observed in conventional synthetic DMARDs. Controlled clinical trials on TNF inhibitors are necessary to test their neuroprotective potentials.

Inflammation, Autoimmunity and Neurodegenerative Diseases, Therapeutics and Beyond

Neurodegenerative disease (ND) incidence has recently increased due to improved life expectancy. Alzheimer's (AD) or Parkinson's disease (PD) are the most prevalent NDs. Both diseases are poly genetic, multifactorial and heterogenous. Preventive medicine, a healthy diet, exercise, and controlling comorbidities may delay the onset. After the diseases are diagnosed, therapy is needed to slow progression. Recent studies show that local, peripheral and age-related inflammation accelerates NDs' onset and progression. Patients with autoimmune disorders like inflammatory bowel disease (IBD) could be at higher risk of developing AD or PD. However, no increase in ND incidence has been reported if the patients are adequately diagnosed and treated. Autoantibodies against abnormal tau, β amyloid and α- synuclein have been encountered in AD and PD and may be protective. This discovery led to the proposal of immune-based therapies for AD and PD involving monoclonal antibodies, immunization/ vaccines, pro-inflammatory cytokine inhibition and anti-inflammatory cytokine addition. All the different approaches have been analysed here. Future perspectives on new therapeutic strategies for both disorders are concisely examined.

Signaling pathways in macrophages: molecular mechanisms and therapeutic targets

Macrophages play diverse roles in development, homeostasis, and immunity. Accordingly, the dysfunction of macrophages is involved in the occurrence and progression of various diseases, such as coronavirus disease 2019 and atherosclerosis. The protective or pathogenic effect that macrophages exert in different conditions largely depends on their functional plasticity, which is regulated via signal transduction such as Janus kinase-signal transducer and activator of transcription, Wnt and Notch pathways, stimulated by environmental cues. Over the past few decades, the molecular mechanisms of signaling pathways in macrophages have been gradually elucidated, providing more alternative therapeutic targets for diseases treatment. Here, we provide an overview of the basic physiology of macrophages and expound the regulatory pathways within them. We also address the crucial role macrophages play in the pathogenesis of diseases, including autoimmune, neurodegenerative, metabolic, infectious diseases, and cancer, with a focus on advances in macrophage-targeted strategies exploring modulation of components and regulators of signaling pathways. Last, we discuss the challenges and possible solutions of macrophage-targeted therapy in clinical applications. We hope that this comprehensive review will provide directions for further research on therapeutic strategies targeting macrophage signaling pathways, which are promising to improve the efficacy of disease treatment.

Rapid improvement in severe long COVID following perispinal etanercept

BACKGROUND

This study aimed to describe the neurological improvements in a patient with severe long COVID brain dysfunction following perispinal etanercept administration. Perispinal administration of etanercept, a novel method designed to enhance its brain delivery via carriage in the cerebrospinal venous system, has previously been shown to reduce chronic neurological dysfunction after stroke. Etanercept is a recombinant biologic that is capable of ameliorating two components of neuroinflammation: microglial activation and the excess bioactivity of tumor necrosis factor (TNF), a proinflammatory cytokine that is a key neuromodulator in the brain. Optimal synaptic and brain network function require physiological levels of TNF. Neuroinflammation, including brain microglial activation and excess central TNF, can be a consequence of stroke or peripheral infection, including infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19.

METHODS

Standardized, validated measures, including the Montreal Cognitive Assessment, Beck Depression Index-II (BDI-II), Fatigue Assessment Scale, Controlled Oral Word Association Test, Trail Making Tests, Timed Finger-to-Nose Test, 20 m Self-Paced Walk Test, 5 Times Sit-to-Stand Test and Grip Strength measured with a Jamar Dynamometer were used to quantitate changes in cognition, depression, fatigue and neurological function after a single 25 mg perispinal etanercept dose in a patient with severe long COVID of 12 months duration.

RESULTS

Following perispinal etanercept administration there was immediate neurological improvement. At 24 h, there were remarkable reductions in chronic post-COVID-19 fatigue and depression, and significant measurable improvements in cognition, executive function, phonemic verbal fluency, balance, gait, upper limb coordination and grip strength. Cognition, depression and fatigue were examined at 29 days; each remained substantially improved.

CONCLUSION

Perispinal etanercept is a promising treatment for the chronic neurologic dysfunction that may persist after resolution of acute COVID-19, including chronic cognitive dysfunction, fatigue, and depression. These results suggest that long COVID brain neuroinflammation is a potentially reversible pathology and viable treatment target. In view of the increasing unmet medical need, clinical trials of perispinal etanercept for long COVID are urgently necessary. The robust results of the present case suggest that perispinal etanercept clinical trials studying long COVID populations with severe fatigue, depression and cognitive dysfunction may have improved ability to detect a treatment effect. Positron emission tomographic methods that image brain microglial activation and measurements of cerebrospinal fluid proinflammatory cytokines may be useful for patient selection and correlation with treatment effects, as well as provide insight into the underlying pathophysiology.

New Possibilities in the Therapeutic Approach to Alzheimer's Disease

Despite the fact that Alzheimer's disease (AD) is the most common cause of dementia, after many years of research regarding this disease, there is no casual treatment. Regardless of the serious public health threat it poses, only five medical treatments for Alzheimer's disease have been authorized, and they only control symptoms rather than changing the course of the disease. Numerous clinical trials of single-agent therapy did not slow the development of disease or improve symptoms when compared to placebo. Evidence indicates that the pathological alterations linked to AD start many years earlier than a manifestation of the disease. In this pre-clinical period before the neurodegenerative process is established, pharmaceutical therapy might prove invaluable. Although recent findings from the testing of drugs such as aducanumab are encouraging, they should nevertheless be interpreted cautiously. Such medications may be able to delay the onset of dementia, significantly lowering the prevalence of the disease, but are still a long way from having a clinically effective disease-modifying therapy.

Potential long-term effect of tumor necrosis factor inhibitors on dementia risk: A propensity score matched retrospective cohort study in US veterans

INTRODUCTION

Tumor necrosis factor (TNF) inhibitors are widely used to treat rheumatoid arthritis (RA) and their potential to retard Alzheimer's disease (AD) progression has been reported. However, their long-term effects on the dementia/AD risk remain unknown.

METHODS

A propensity scored matched retrospective cohort study was conducted among 40,207 patients with RA within the US Veterans Affairs health-care system from 2000 to 2020.

RESULTS

A total of 2510 patients with RA prescribed TNF inhibitors were 1:2 matched to control patients. TNF inhibitor use was associated with reduced dementia risk (hazard ratio [HR]: 0.64, 95% confidence interval [CI]: 0.52-0.80), which was consistent as the study period increased from 5 to 20 years after RA diagnosis. TNF inhibitor use also showed a long-term effect in reducing the risk of AD (HR: 0.57, 95% CI: 0.39-0.83) during the 20 years of follow-up.

CONCLUSION

TNF inhibitor use is associated with lower long-term risk of dementia/AD among US veterans with RA.

Obesity and the Brain

Innate and adaptive immunity are essential for neurodevelopment and central nervous system (CNS) homeostasis; however, the fragile equilibrium between immune and brain cells can be disturbed by any immune dysregulation and cause detrimental effects. Accumulating evidence indicates that, despite the blood-brain barrier (BBB), overactivation of the immune system leads to brain vulnerability that increases the risk of neuropsychiatric disorders, particularly upon subsequent exposure later in life. Disruption of microglial function in later life can be triggered by various environmental and psychological factors, including obesity-driven chronic low-grade inflammation and gut dysbiosis. Increased visceral adiposity has been recognized as an important risk factor for multiple neuropsychiatric conditions. The review aims to present our current understanding of the topic.

ZNF384: A Potential Therapeutic Target for Psoriasis and Alzheimer’s Disease Through Inflammation and Metabolism

Background

Psoriasis is an immune-related skin disease notable for its chronic inflammation of the entire system. Alzheimer’s disease (AD) is more prevalent in psoriasis than in the general population. Immune-mediated pathophysiologic processes may link these two diseases, but the mechanism is still unclear. This article aimed to explore potential molecular mechanisms in psoriasis and AD.

Methods

Gene expression profiling data of psoriasis and AD were acquired in the Gene Expression Omnibus (GEO) database. Gene Set Enrichment Analysis (GSEA) and single-sample GSEA (ssGSEA) were first applied in two datasets. Differentially expressed genes (DEGs) of two diseases were identified, and common DEGs were selected. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis was performed to explore common biological pathways. Signature transcription factors (STFs) were identified and their diagnostic values was calculated by receiver operating characteristic (ROC) curve analysis in the exploration cohort and verified in the validation cohort. The expression levels of STFs were further investigated in the validation cohort and the GTEx Portal Database. Additionally, four kinds of interaction analysis were performed: correlation analysis among STFs, gene-gene, chemical-protein, and protein-ligand interaction analyses. In the end, we predicted the transcription factor that potentially regulates STFs.

Results

Biosynthesis and metabolic pathways were enriched in GSEA analysis. In ssGSEA analysis, most immunoreaction gene lists exhibited differential enrichment in psoriasis cases, whereas three receptor-related gene lists did in AD. The KEGG analysis of common DEGs redetermined inflammatory and metabolic pathways essential in both diseases. 5 STFs (PPARG, ZFPM2, ZNF415, HLX, and ANHX) were screened from common DEGs. The ROC analysis indicated that all STFs have diagnostic values in two diseases, especially ZFPM2. The correlation analysis, gene-gene, chemical-protein, and protein-ligand interaction analyses suggested that STFs interplay and involve inflammation and aberrant metabolism. Eventually, ZNF384 was the predicted transcription factor regulating PPARG, ZNF415, HLX, and ANHX.

Conclusions

The STFs (PPARG, ZFPM2, ZNF415, HLX, and ANHX) may increase the morbidity rate of AD in psoriasis by initiating a positive feedback loop of excessive inflammation and metabolic disorders. ZNF384 is a potential therapeutic target for psoriasis and AD by regulating PPARG, ZNF415, HLX, and ANHX.

Mechanisms Involved in Microglial-Interceded Alzheimer's Disease and Nanocarrier-Based Treatment Approaches

Alzheimer's disease (AD) is a common neurodegenerative disorder accountable for dementia and cognitive dysfunction. The etiology of AD is complex and multifactorial in origin. The formation and deposition of amyloid-beta (Aβ), hyperphosphorylated tau protein, neuroinflammation, persistent oxidative stress, and alteration in signaling pathways have been extensively explored among the various etiological hallmarks. However, more recently, the immunogenic regulation of AD has been identified, and macroglial activation is considered a limiting factor in its etiological cascade. Macroglial activation causes neuroinflammation via modulation of the NLRP3/NF-kB/p38 MAPKs pathway and is also involved in tau pathology via modulation of the GSK-3β/p38 MAPK pathways. Additionally, microglial activation contributes to the discrete release of neurotransmitters and an altered neuronal synaptic plasticity. Therefore, activated microglial cells appear to be an emerging target for managing and treating AD. This review article discussed the pathology of microglial activation in AD and the role of various nanocarrier-based anti-Alzeihmenr's therapeutic approaches that can either reverse or inhibit this activation. Thus, as a targeted drug delivery system, nanocarrier approaches could emerge as a novel means to overcome existing AD therapy limitations.

Therapeutic Potential of TNF-α Inhibition for Alzheimer's Disease Prevention

Background:

Alzheimer’s disease (AD) is increasingly prevalent and over 99% of drugs developed for AD have failed in clinical trials. A growing body of literature suggests that potent inhibitors of tumor necrosis factor-α (TNF-α) have potential to improve cognitive performance.

Objective:

In this review, we summarize the evidence regarding the potential for TNF-α inhibition to prevent AD and improve cognitive function in people at risk for dementia.

Methods:

We conducted a literature review in PubMed, screening all articles published before July 7, 2019 related to TNF blocking agents and curcumin (another TNF-α inhibitor) in the context of AD pathology. The keywords in the search included: AD, dementia, memory, cognition, TNF-α, TNF inhibitors, etanercept, infliximab, adalimumab, golimumab, and curcumin.

Results:

Three large epidemiology studies reported etanercept treated patients had 60 to 70% lower odds ratio (OR) of developing AD. Two small-randomized control trials (RCTs) demonstrated an improvement in cognitive performance for AD patients treated with etanercept. Studies using animal models of dementia also reported similar findings with TNF blocking agents (etanercept, infliximab, adalimumab, Theracurmin), which appeared to improve cognition. A small human RCT using Theracurmin, a well-absorbed form of curcumin that lowers TNF-α, showed enhanced cognitive performance and decreased brain levels of amyloid-β plaque and tau tangles.

Conclusion:

TNF-α targeted therapy is a biologically plausible approach to the preservation of cognition, and warrants larger prospective RCTs to further investigate potential benefits in populations at risk of developing AD.

Neuroinflammation and microglial activation in Alzheimer disease: where do we go from here?

Alzheimer disease (AD) is the most common form of neurodegenerative disease, estimated to contribute 60-70% of all cases of dementia worldwide. According to the prevailing amyloid cascade hypothesis, amyloid-β (Aβ) deposition in the brain is the initiating event in AD, although evidence is accumulating that this hypothesis is insufficient to explain many aspects of AD pathogenesis. The discovery of increased levels of inflammatory markers in patients with AD and the identification of AD risk genes associated with innate immune functions suggest that neuroinflammation has a prominent role in the pathogenesis of AD. In this Review, we discuss the interrelationships between neuroinflammation and amyloid and tau pathologies as well as the effect of neuroinflammation on the disease trajectory in AD. We specifically focus on microglia as major players in neuroinflammation and discuss the spatial and temporal variations in microglial phenotypes that are observed under different conditions. We also consider how these cells could be modulated as a therapeutic strategy for AD.

Pharmacological Inhibition of Amyloidogenic APP Processing and Knock-Down of APP in Primary Human Macrophages Impairs the Secretion of Cytokines

It has been previously shown that the amyloid precursor protein (APP) support the innate immune defense as an immune receptor. Amyloid β (Aβ) peptides seem to have properties of an antimicrobial peptide and can act as opsonines. In APP-deficient mouse models, a reduced secretion of cytokines has been observed. Still, it is unclear whether this can be attributed to the lack of APP or to the missing secretion of Aβ peptides. We inhibited the secretion of Aβ peptides in primary human monocyte derived macrophages with the γ-secretase inhibitor N-[N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine-t-butyl-ester (DAPT) or the β-secretase inhibitor GL-189. Alternatively, we knocked down APP by transfection with siRNA. We measured tumor necrosis factor α (TNFα), interleukin 6 (IL-6) and interleukin (IL-10) by enzyme linked immunosorbent assay (ELISA) and evaluated the phagocytotic activity by flow cytometry. We observed reduced concentrations of TNFα and IL-6 in the media of APP^k/d macrophages and after inhibition of the β-, or γ-secretase, especially after additional immunological activation with lipopolysaccharide (LPS). Secretion of IL-10 was increased after pharmacological inhibition of APP processing when the macrophages were not immunologically activated but was decreased during LPS-induced inflammation in APP^k/d macrophages. No changes of the phagocytotic activity were observed. We conclude that macrophage APP and Aβ peptides support the initiation of an immune response and are involved in the regulation of TNFα, IL-6, and IL-10 secretion by human monocyte-derived macrophages.

Cognitive impairment in elderly patients with rheumatic disease and the effect of disease-modifying anti-rheumatic drugs

Recent development of biologic disease-modifying anti-rheumatic drugs (DMARDs) has led to better control of disease activity among patients with chronic rheumatological diseases. Many patients with rheumatic disease are living longer, adding to the growing elderly population. Rheumatic diseases, most notably rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), are known to increase the risk of cognitive impairment. Systemic inflammation associated with chronic rheumatological diseases has been postulated to be key driver of cognitive decline. Recent development of classic and biologic DMARDs have led to better control of disease activity among patients with rheumatic conditions. It is proposed that strict control of systemic inflammation will significantly lower the risk of cognitive impairment among patients with rheumatic disease. The impact of classic DMARDs on cognitive function appears to be variable. On the other hand, biologic DMARDs, specifically antitumor necrosis factor (TNF) drugs (i.e., etanercept), have been shown to significantly lower the risk of dementia. Experimental studies on IL-1, IL-6, and B and T cell blockade are promising. However, clinical data is limited. Preclinical studies on targeted therapies, specifically JAK/STAT inhibitors, also show promising results. Additional studies are necessary to better understand the impact of these newer biologic agents on cognitive function in elderly patients with rheumatic disease. Key points • Patients with chronic rheumatic conditions are beginning to live longer, adding to the elderly population. • Patients with chronic rheumatologic disease are at increased risk of cognitive impairment compared to the general population. • Recent development of biologic (i.e., TNF, IL-1, IL-6) and targeted drugs (i.e., Janus kinase inhibitors) have led to better control of disease activity. • Current evidence suggests that TNF inhibitors may have beneficial effects on cognitive function. However, evidence on newer biologic and targeted therapies is limited.

Increased risk of Alzheimer's disease in patients with psoriasis: a nationwide population-based cohort study

Although the pathogenesis of Alzheimer’s disease (AD) is unclear, neuroinflammation appears to play a role in its development. Psoriasis is a chronic inflammatory skin disease that has recently been found to genetically overlap with AD. We aimed to investigate the risk of AD in patients with psoriasis. Subjects with psoriasis (n = 535,927) and age- and sex-matched controls without psoriasis (at a 5:1 ratio; n = 2,679,635) who underwent ≥3 health examinations between 2008 and 2014 were included, drawn from the Korean National Health Insurance System database. There were 50,209 cases of AD (1.87%) in controls without psoriasis and 11,311 cases (2.11%) in patients with psoriasis, and the median follow-up was 3.35 years. In a multivariable-adjusted model, patients with psoriasis showed a significantly increased risk of AD (hazard ratio, 1.09; 95% CI, 1.07–1.12, p < 0.0001) compared to controls without psoriasis. Among patients with psoriasis, the risk of AD was significantly increased in psoriasis patients not receiving systemic therapy compared to those receiving systemic therapy (hazard ratio, 1.10; 95% CI, 1.08–1.12 vs. hazard ratio, 0.99; 95% CI: 0.90–1.09, p < 0.0001). The incidence of AD was significantly increased in patients with psoriasis compared to control subjects without psoriasis. Of note, systemic treatment for psoriasis was associated with a reduced risk of AD.

Anti-Tumor Necrosis Factor Therapy and Incidence of Parkinson Disease Among Patients With Inflammatory Bowel Disease

Importance

Despite established genetic and pathophysiologic links between inflammatory bowel disease (IBD) and Parkinson disease (PD), clinical data supporting this association remain scarce. Although systemic inflammation is considered a potential biological mechanism shared between the 2 diseases, the role of reduced systemic inflammation through IBD-directed anti-tumor necrosis factor (anti-TNF) therapy in PD risk is largely unknown.

Objective

To compare the incidence of PD among individuals with or without IBD and to assess whether PD risk among patients with IBD is altered by anti-TNF therapy.

Design, Setting, and Participants

This is a retrospective cohort study analyzing information in the Truven Health MarketScan administrative claims database and the Medicare Supplemental Database between January 1, 2000, and March 31, 2016. Individuals were selected who had at least 2 claims for IBD diagnoses, at least 6 months of follow-up, and no prior diagnosis of PD on or before the IBD index date. Exposure to Anti-TNF therapy was measured from the anti-TNF index date to the last date of anti-TNF coverage or the end of enrollment or PD index date, whichever was earliest. Incidence rates per 1000 person-years were calculated, and crude and adjusted incidence rate ratios were estimated by Poisson regression models and presented with 95% CIs.

Main Outcomes and Measures

Incidence of PD among patients with IBD with or without exposure to anti-TNF therapy.

Results

In total, 144 018 individuals with IBD were matched on age, sex, and year of index date with 720 090 unaffected controls. Of them, 1796 individuals had at least 2 PD diagnoses and at least 1 filled PD-related prescription. The mean (SD) age of individuals with IBD was 51 (17) years, and 44% were men. The incidence of PD among patients with IBD was 28% higher than that among unaffected matched controls (adjusted incidence rate ratio, 1.28; 95% CI, 1.14-1.44; P < .001). A 78% reduction in the incidence rate of PD was detected among patients with IBD who were exposed to anti-TNF therapy compared with those who were not exposed (adjusted incidence rate ratio, 0.22; 95% CI, 0.05-0.88; P = .03).

Conclusions and Relevance

A higher incidence of PD was observed among patients with IBD than among individuals without IBD. Early exposure to antiinflammatory anti-TNF therapy was associated with substantially reduced PD incidence. These findings support a role of systemic inflammation in the pathogenesis of both diseases. Further studies are required to determine whether anti-TNF treatment administered to high-risk individuals may mitigate PD risk.

Passive Immunotherapies for Central Nervous System Disorders: Current Delivery Challenges and New Approaches

Passive immunotherapy, i.e., the administration of exogenous antibodies that recognize a specific target antigen, has gained significant momentum as a potential treatment strategy for several central nervous system (CNS) disorders, including Alzheimer's disease, Parkinson's disease, Huntington's disease, and brain cancer, among others. Advances in antibody engineering to create therapeutic antibody fragments or antibody conjugates have introduced new strategies that may also be applied to treat CNS disorders. However, drug delivery to the CNS for antibodies and other macromolecules has thus far proven challenging, due in large part to the blood-brain barrier and blood-cerebrospinal fluid barriers that greatly restrict transport of peripherally administered molecules from the systemic circulation into the CNS. Here, we summarize the various passive immunotherapy approaches under study for the treatment of CNS disorders, with a primary focus on disease-specific and target site-specific challenges to drug delivery and new, cutting edge methods.

DMARD use is associated with a higher risk of dementia in patients with rheumatoid arthritis: A propensity score-matched case-control study

BACKGROUND

Patients with rheumatoid arthritis (RA) exhibit an increased risk of dementia. Disease-modifying antirheumatic drugs (DMARDs) are commonly used to slow RA progression, but studies investigating the relationship between DMARDs and dementia in patients with RA are lacking. We investigated the relationship between DMARDs and dementia in patients with RA.

METHODS

Using the National Health Insurance Research Database, patients aged ≥20years, who were newly diagnosed with RA between 2000 and 2011 were identified. Patients with RA who had dementia comprised the dementia group, and patients with RA who did not have dementia comprised the control group. The groups were matched at a 1:1 ratio by the propensity score. DMARDs were categorized into conventional synthetic DMARDs (csDMARDs) and biological DMARDs (bDMARDs). Logistic regression models were used to calculate the odds ratio and 95% confidence interval (CI) to evaluate the association between DMARD use and the risk of dementia in patients with RA.

RESULTS

A total of 957 patients with RA and dementia, and 957 patients with RA but not dementia, were enrolled. The risk of dementia was determined to be 1.63-fold higher in patients with RA with csDMARD use than in those without csDMARD use (95% CI=1.33-2.00). No significant risk of dementia was observed in patients with RA who used bDMARDs compared with their counterparts. However, patients with RA who used hydroxychloroquine, methotrexate, and sulfasalazine exhibited significant risks of dementia, irrespective of cumulative exposure days.

CONCLUSION

Patients with RA who used csDMARDs exhibit significant association with dementia.

LW-AFC, a new formula derived from Liuwei Dihuang decoction, ameliorates behavioral and pathological deterioration via modulating the neuroendocrine-immune system in PrP-hAβPPswe/PS1ΔE9 transgenic mice

BACKGROUND

Accumulating evidence implicates the neuroendocrine immunomodulation (NIM) network in the physiopathological mechanism of Alzheimer's disease (AD). Notably, we previously revealed that the NIM network is dysregulated in the PrP-hAβPPswe/PS1ΔE9 (APP/PS1) transgenic mouse model of AD.

METHODS

After treatment with a novel Liuwei Dihuang formula (LW-AFC), mice were cognitively evaluated in behavioral experiments. Neuron loss, amyloid-β (Aβ) deposition, and Aβ level were analyzed using Nissl staining, immunofluorescence, and an AlphaLISA assay, respectively. Multiplex bead analysis, a radioimmunoassay, immunochemiluminometry, and an enzyme-linked immunosorbent assay (ELISA) were used to measure cytokine and hormone levels. Lymphocyte subsets were detected using flow cytometry. Data between two groups were compared using a Student's t test. Comparison of the data from multiple groups against one group was performed using a one-way analysis of variance (ANOVA) followed by a Dunnett's post hoc test or a two-way repeated-measures analysis of variance with a Tukey multiple comparisons test.

RESULTS

LW-AFC ameliorated the cognitive impairment observed in APP/PS1 mice, including the impairment of object recognition memory, spatial learning and memory, and active and passive avoidance. In addition, LW-AFC alleviated the neuron loss in the hippocampus, suppressed Aβ deposition in the brain, and reduced the concentration of Aβ1-42 in the hippocampus and plasma of APP/PS1 mice. LW-AFC treatment also significantly decreased the secretion of corticotropin-releasing hormone and gonadotropin-releasing hormone in the hypothalamus, and adrenocorticotropic hormone, luteinizing hormone, and follicle-stimulating hormone in the pituitary. Moreover, LW-AFC increased CD8+CD28+ T cells, and reduced CD4+CD25+Foxp3+ T cells in the spleen lymphocytes, downregulated interleukin (IL)-1β, IL-2, IL-6, IL-23, granulocyte-macrophage colony stimulating factor, and tumor necrosis factor-α and -β, and upregulated IL-4 and granulocyte colony stimulating factor in the plasma of APP/PS1 mice.

CONCLUSIONS

LW-AFC ameliorated the behavioral and pathological deterioration of APP/PS1 transgenic mice via the restoration of the NIM network to a greater extent than either memantine or donepezil, which supports the use of LW-AFC as a potential agent for AD therapy.

Cytokines and Cytokine Receptors Involved in the Pathogenesis of Alzheimer's Disease

Inflammatory mechanisms are implicated in the pathology of Alzheimer's disease (AD). However, it is unclear whether inflammatory alterations are a cause or consequence of neurodegeneration leading to dementia. Clarifying this issue would provide valuable insight into the early diagnosis and therapeutic management of AD. To address this, we compared the mRNA expression profiles of cytokines in the brains of AD patients with "non-demented individuals with AD pathology" and non-demented healthy control (ND) individuals. "Non-demented individuals with AD pathology" are referred to as high pathology control (HPC) individuals that are considered an intermediate subset between AD and ND. HPC represents a transition between normal aging and early stage of AD, and therefore, is useful for determining whether neuroinflammation is a cause or consequence of AD pathology. We observed that immunological conditions that produce cytokines in the HPC brain were more representative of ND than AD. To validate these result, we investigated the expression of inflammatory mediators at the protein level in postmortem brain tissues. We examined the protein expression of tumor necrosis factor (TNF)α and its receptors (TNFRs) in the brains of AD, HPC, and ND individuals. We found differences in soluble TNFα and TNFRs expression between AD and ND groups and between AD and HPC groups. Expression in the temporal cortex was lower in the AD brains than HPC and ND. Our findings indicate that alterations in immunological conditions involving TNFR-mediated signaling are not the primary events initiating AD pathology, such as amyloid plaques and tangle formation. These may be early events occurring along with synaptic and neuronal changes or later events caused by these changes. In this review, we emphasize that elucidating the temporal expression of TNFα signaling molecules during AD is important to understand the selective tuning of these pathways required to develop effective therapeutic strategies for AD.

Elevated peripheral cytokines characterize a subgroup of people with schizophrenia displaying poor verbal fluency and reduced Broca's area volume

Previous studies on schizophrenia have detected elevated cytokines in both brain and blood, suggesting neuroinflammation may contribute to the pathophysiology in some cases. We aimed to determine the extent to which elevated peripheral cytokine messenger RNA (mRNA) expression: (1) characterizes a subgroup of people with schizophrenia and (2) shows a relationship to cognition, brain volume and/or symptoms. Forty-three outpatients with schizophrenia or schizoaffective disorder and matched healthy controls were assessed for peripheral cytokine mRNAs (interleukin (IL)-1β, IL-2, IL-6, IL-8 and IL-18), intelligence quotient, memory and verbal fluency, symptom severity and cortical brain volumes integral to language (that is, Broca's and Wernicke's areas). IL-1β mRNA levels were 28% increased in schizophrenia compared with controls (t(82)=2.64, P<0.01). Using a two-step clustering procedure, we identified a subgroup of people displaying relatively elevated cytokine mRNA levels (17/43 people with schizophrenia and 9/42 controls). Individuals with schizophrenia in the elevated cytokine subgroup performed significantly worse than the low-cytokine subgroup on verbal fluency (F(1,40)=15.7, P<0.001). There was a 17% volume reduction of the left pars opercularis (POp) (Broca's area) in patients with elevated cytokines compared with patients with lower cytokines (F(1,29)=9.41, P=0.005). Negative linear relationships between IL-1β mRNA levels and both verbal fluency and left POp volume were found in schizophrenia. This study is among the first to link blood biomarkers of inflammation with both cognitive deficits and brain volume reductions in people with schizophrenia, supporting that those with elevated cytokines represent a neurobiologically meaningful subgroup. These findings raise the possibility that targeted anti-inflammatory treatments may ameliorate cognitive and brain morphological abnormalities in some people with schizophrenia.

A Two-Year Treatment of Amnestic Mild Cognitive Impairment using a Compound Chinese Medicine: A Placebo Controlled Randomized Trial

We aimed to investigate the long-term therapeutic effects of a compound Chinese medicine, the Bushen capsule, on cognition and brain connectivity in patients with amnestic mild cognitive impairment (aMCI). Thus, sixty aMCI participants were recruited to this 24-month study and were randomly divided into treatment (30 with a Bushen capsule) and placebo (30 with a placebo capsule) groups. Neuropsychological tests with MMSE and episodic memory as the primary outcomes and resting-state functional magnetic resonance imaging (fMRI) were analyzed before and after the treatment over 24 month period. In contrast to the placebo group, the drug group presented improved or stable general cognitive function, memory, language and executive function especially the primary outcomes MMSE and episodic memory with Bushen capsule treatment. FMRI results showed increased connectivity in the right precuneus and the global connectivity indexed with goodness of fit (GOF) of the default mode network (DMN) in the drug group and decreased GOF in the placebo group. More importantly, we found the GOF change was positively correlated with changes in MMSE and memory scores after 24 months in the drug group. Over 24 months, treatment with the compound Chinese medicine Bushen capsule can improve multiple domains of cognition and increase the functional local (right precuneus) and global connectivity within the DMN, which are associated with better performance.

Combined Intraperitoneal and Intrathecal Etanercept Reduce Increased Brain Tumor Necrosis Factor-Alpha and Asymmetric Dimethylarginine Levels and Rescues Spatial Deficits in Young Rats after Bile Duct Ligation

BACKGROUND

Rats subjected to bile duct ligation (BDL) exhibit increased systemic oxidative stress and brain dysfunction characteristic of hepatic encephalopathy (HE), including fatigue, neurotransmitter alterations, cognitive and motor impairment, and brain inflammation. The levels of tumor necrosis factor-alpha (TNF-α) and asymmetric dimethylarginine (ADMA) are both increased in plasma and brain in encephalopathy induced by chronic liver failure. This study first determined the temporal profiles of TNF-α and ADMA in the plasma, brain cortex, and hippocampus in young BDL rats. Next, we examined whether etanercept was beneficial in preventing brain damage.

METHODS

Young rats underwent sham ligation or BDL at day 17 ± 1 for 4 weeks. Treatment group rats were administered etanercept (10 mg/kg) intraperitoneally (IP) three times per week with or without etanercept (100 μg) intrathecally (IT) three times in total.

RESULTS

We found increased plasma TNF-α, soluble tumor necrosis factor receptor 1 (sTNFR1), soluble tumor necrosis factor receptor 2 (sTNFR2), and ADMA levels, increased cortical TNF-α mRNA and protein and ADMA, and hippocampal TNF-α mRNA and protein, and spatial defects in young BDL rats. The increase in cortex TNF-α mRNA and ADMA were reduced by IP etanercept or combined IP and IT etanercept. Dually IP/IT etanercept administration reduced the increased cortical and hippocampal TNF-α mRNA and protein level as well as spatial deficits.

CONCLUSIONS

We conclude that combined intraperitoneal and intrathecal etanercept reduce increased brain TNF-α and ADMA levels and rescues spatial deficits in young rats after BDL.

Perispinal Delivery of CNS Drugs

Perispinal injection is a novel emerging method of drug delivery to the central nervous system (CNS). Physiological barriers prevent macromolecules from efficiently penetrating into the CNS after systemic administration. Perispinal injection is designed to use the cerebrospinal venous system (CSVS) to enhance delivery of drugs to the CNS. It delivers a substance into the anatomic area posterior to the ligamentum flavum, an anatomic region drained by the external vertebral venous plexus (EVVP), a division of the CSVS. Blood within the EVVP communicates with the deeper venous plexuses of the CSVS. The anatomical basis for this method originates in the detailed studies of the CSVS published in 1819 by the French anatomist Gilbert Breschet. By the turn of the century, Breschet's findings were nearly forgotten, until rediscovered by American anatomist Oscar Batson in 1940. Batson confirmed the unique, linear, bidirectional and retrograde flow of blood between the spinal and cerebral divisions of the CSVS, made possible by the absence of venous valves. Recently, additional supporting evidence was discovered in the publications of American neurologist Corning. Analysis suggests that Corning's famous first use of cocaine for spinal anesthesia in 1885 was in fact based on Breschet's anatomical findings, and accomplished by perispinal injection. The therapeutic potential of perispinal injection for CNS disorders is highlighted by the rapid neurological improvement in patients with otherwise intractable neuroinflammatory disorders that may ensue following perispinal etanercept administration. Perispinal delivery merits intense investigation as a new method of enhanced delivery of macromolecules to the CNS and related structures.

Immediate neurological recovery following perispinal etanercept years after brain injury

Positron emission tomographic brain imaging and pathological examination have revealed that a chronic, intracerebral neuroinflammatory response lasting for years after a single brain injury may occur in humans. Evidence suggests the immune signaling molecule, tumor necrosis factor (TNF), is centrally involved in this pathology through its modulation of microglial activation, role in synaptic dysfunction, and induction of depressive symptoms and neuropathic pain. Etanercept is a recombinant TNF receptor fusion protein and potent TNF inhibitor that has been found to reduce microglial activation and neuropathic pain in multiple experimental models. We report that a single dose of perispinal etanercept produced an immediate, profound, and sustained improvement in expressive aphasia, speech apraxia, and left hemiparesis in a patient with chronic, intractable, debilitating neurological dysfunction present for more than 3 years after acute brain injury. These results indicate that acute brain injury-induced pathologic levels of TNF may provide a therapeutic target that can be addressed years after injury. Perispinal administration of etanercept is capable of producing immediate relief from brain injury-mediated neurological dysfunction.

Etanercept in Alzheimer disease: A randomized, placebo-controlled, double-blind, phase 2 trial

OBJECTIVES

To determine whether the tumor necrosis factor α inhibitor etanercept is well tolerated and obtain preliminary data on its safety in Alzheimer disease dementia.

METHODS

In a double-blind study, patients with mild to moderate Alzheimer disease dementia were randomized (1:1) to subcutaneous etanercept (50 mg) once weekly or identical placebo over a 24-week period. Tolerability and safety of this medication was recorded including secondary outcomes of cognition, global function, behavior, and systemic cytokine levels at baseline, 12 weeks, 24 weeks, and following a 4-week washout period. This trial is registered with EudraCT (2009-013400-31) and ClinicalTrials.gov (NCT01068353).

RESULTS

Forty-one participants (mean age 72.4 years; 61% men) were randomized to etanercept (n = 20) or placebo (n = 21). Etanercept was well tolerated; 90% of participants (18/20) completed the study compared with 71% (15/21) in the placebo group. Although infections were more common in the etanercept group, there were no serious adverse events or new safety concerns. While there were some interesting trends that favored etanercept, there were no statistically significant changes in cognition, behavior, or global function.

CONCLUSIONS

This study showed that subcutaneous etanercept (50 mg/wk) was well tolerated in this small group of patients with Alzheimer disease dementia, but a larger more heterogeneous group needs to be tested before recommending its use for broader groups of patients.

CLASSIFICATION OF EVIDENCE

This study shows Class I evidence that weekly subcutaneous etanercept is well tolerated in Alzheimer disease dementia.

The Involvement of TNF-α in Cognitive Dysfunction Associated with Major Depressive Disorder: An Opportunity for Domain Specific Treatments

Major depressive disorder is a highly prevalent, chronic and recurring disorder, associated with substantial impairment in cognitive and interpersonal functions. Accumulating evidence suggests that inflammatory processes play an important role in the etio-pathogenesis, phenomenology, comorbidity and treatment of MDD. Suboptimal remission rates and the persistence of cognitive deficits contribute to functional impairment in MDD inviting the need for the development of mechanistically novel and domain specific treatment approaches. The MEDLINE/ Pubmed database was searched from inception to February, 9th, 2014 with combinations of the following search terms: 'TNF-alpha', 'depression', 'infliximab', 'etanercept', 'adalimumab', 'golimumab' and 'certolizumab'. Preclinical and clinical evidence linking TNF-α to MDD pathophysiology were reviewed as well as the current status of TNF-α modulators as novel agents for the treatment of MDD. Experimental models and clinical studies provide encouraging preliminary evidence for the efficacy of TNF- α antagonists in mitigating depressive symptoms and improving cognitive deficits. Further studies are warranted to confirm these data in larger randomized controlled trials in primary psychiatric populations. Translational research provides a promising perspective that may aid the development and/or repurposing of mechanism-based treatments for depressive symptoms and cognitive impairment in MDD.

Search for age-related macular degeneration risk variants in Alzheimer disease genes and pathways

Several lines of inquiry point to overlapping molecular mechanisms between late-onset Alzheimer disease (AD) and age-related macular degeneration (AMD). We evaluated summarized results from large genome-wide association studies for AD and AMD to test the hypothesis that AD susceptibility loci are also associated with AMD. We observed association of both disorders with genes in a region of chromosome 7, including PILRA and ZCWPW1 (peak AMD SNP rs7792525, minor allele frequency [MAF] = 19%, odds ratio [OR] = 1.14, p = 2.34 × 10(-6)), and with ABCA7 (peak AMD SNP rs3752228, MAF = 0.054, OR = 1.22, p = 0.00012). Next, we evaluated association of AMD with genes in AD-related pathways identified by canonical pathway analysis of AD-associated genes. Significant associations were observed with multiple previously identified AMD risk loci and 2 novel genes: HGS (peak SNP rs8070488, MAF = 0.23, OR = 0.91, p = 7.52 × 10(-5)), which plays a role in the clathrin-mediated endocytosis signaling pathway, and TNF (peak SNP rs2071590, MAF = 0.34, OR = 0.89, p = 1.17 × 10(-5)), which is a member of the atherosclerosis signaling and the LXR/RXR activation pathways. Our results suggest that AMD and AD share genetic mechanisms.

Tumor necrosis factor alpha: a link between neuroinflammation and excitotoxicity

Tumor necrosis factor alpha (TNF-α) is a proinflammatory cytokine that exerts both homeostatic and pathophysiological roles in the central nervous system. In pathological conditions, microglia release large amounts of TNF-α; this de novo production of TNF-α is an important component of the so-called neuroinflammatory response that is associated with several neurological disorders. In addition, TNF-α can potentiate glutamate-mediated cytotoxicity by two complementary mechanisms: indirectly, by inhibiting glutamate transport on astrocytes, and directly, by rapidly triggering the surface expression of Ca⁺² permeable-AMPA receptors and NMDA receptors, while decreasing inhibitory GABA_A receptors on neurons. Thus, the net effect of TNF-α is to alter the balance of excitation and inhibition resulting in a higher synaptic excitatory/inhibitory ratio. This review summarizes the current knowledge of the cellular and molecular mechanisms by which TNF-α links the neuroinflammatory and excitotoxic processes that occur in several neurodegenerative diseases, but with a special emphasis on amyotrophic lateral sclerosis (ALS). As microglial activation and upregulation of TNF-α expression is a common feature of several CNS diseases, as well as chronic opioid exposure and neuropathic pain, modulating TNF-α signaling may represent a valuable target for intervention.

Perispinal etanercept for post-stroke neurological and cognitive dysfunction: scientific rationale and current evidence

There is increasing recognition of the involvement of the immune signaling molecule, tumor necrosis factor (TNF), in the pathophysiology of stroke and chronic brain dysfunction. TNF plays an important role both in modulating synaptic function and in the pathogenesis of neuropathic pain. Etanercept is a recombinant therapeutic that neutralizes pathologic levels of TNF. Brain imaging has demonstrated chronic intracerebral microglial activation and neuroinflammation following stroke and other forms of acute brain injury. Activated microglia release TNF, which mediates neurotoxicity in the stroke penumbra. Recent observational studies have reported rapid and sustained improvement in chronic post-stroke neurological and cognitive dysfunction following perispinal administration of etanercept. The biological plausibility of these results is supported by independent evidence demonstrating reduction in cognitive dysfunction, neuropathic pain, and microglial activation following the use of etanercept, as well as multiple studies reporting improvement in stroke outcome and cognitive impairment following therapeutic strategies designed to inhibit TNF. The causal association between etanercept treatment and reduction in post-stroke disability satisfy all of the Bradford Hill Criteria: strength of the association; consistency; specificity; temporality; biological gradient; biological plausibility; coherence; experimental evidence; and analogy. Recognition that chronic microglial activation and pathologic TNF concentration are targets that may be therapeutically addressed for years following stroke and other forms of acute brain injury provides an exciting new direction for research and treatment.

Advanced BrainAGE in older adults with type 2 diabetes mellitus

Aging alters brain structure and function and diabetes mellitus (DM) may accelerate this process. This study investigated the effects of type 2 DM on individual brain aging as well as the relationships between individual brain aging, risk factors, and functional measures. To differentiate a pattern of brain atrophy that deviates from normal brain aging, we used the novel BrainAGE approach, which determines the complex multidimensional aging pattern within the whole brain by applying established kernel regression methods to anatomical brain magnetic resonance images (MRI). The “Brain Age Gap Estimation” (BrainAGE) score was then calculated as the difference between chronological age and estimated brain age. 185 subjects (98 with type 2 DM) completed an MRI at 3Tesla, laboratory and clinical assessments. Twenty-five subjects (12 with type 2 DM) also completed a follow-up visit after 3.8 ± 1.5 years. The estimated brain age of DM subjects was 4.6 ± 7.2 years greater than their chronological age (p = 0.0001), whereas within the control group, estimated brain age was similar to chronological age. As compared to baseline, the average BrainAGE scores of DM subjects increased by 0.2 years per follow-up year (p = 0.034), whereas the BrainAGE scores of controls did not change between baseline and follow-up. At baseline, across all subjects, higher BrainAGE scores were associated with greater smoking and alcohol consumption, higher tumor necrosis factor alpha (TNFα) levels, lower verbal fluency scores and more severe deprepession. Within the DM group, higher BrainAGE scores were associated with longer diabetes duration (r = 0.31, p = 0.019) and increased fasting blood glucose levels (r = 0.34, p = 0.025). In conclusion, type 2 DM is independently associated with structural changes in the brain that reflect advanced aging. The BrainAGE approach may thus serve as a clinically relevant biomarker for the detection of abnormal patterns of brain aging associated with type 2 DM.

The specific PKR inhibitor C16 prevents apoptosis and IL-1β production in an acute excitotoxic rat model with a neuroinflammatory component

The double-stranded RNA-dependent protein kinase (PKR), an apoptotic inducer, regulates much pro-inflammatory cytokine production. The purpose of this study was to evaluate in vivo the effects of the specific PKR inhibitor C16 in the striatum in an acute excitotoxic rat model with an important neuroinflammatory component. Inflammation was induced by unilateral striatal injection of quinolinic acid (QA) in 10-week-old normotensive rats. Animals were separated into groups receiving either vehicle or C16 for both sham and QA rats. The effects were assessed in ipsi- and contralateral striata by immunoblotting for PKR activation, by Luminex assay for cytokine levels and by immunofluorescent staining for cleaved caspase-3 to detect neuronal apoptosis. The highest dose of C16 (600μg/kg; C16-2) in QA rats reduced expression of the active catalytic domain of the PKR vs. that in vehicle-injected QA rats. A robust increase of IL-1β levels on the contralateral side of QA rats was prevented by C16-2 (97% inhibition). Macroscopic and microscopic observation of cerebral tissue (Hematoxylin & Eosin staining) revealed that tissue integrity was more preserved with C16-2 treatment than its vehicle in QA rats. Furthermore, C16-2 treatment decreased by 47% the neuronal loss and by 37% the number of positive cleaved caspase-3 neurons induced by QA injection. In conclusion, C16 prevented not only the PKR-induced neuronal loss but also the inflammatory response in this acute excitotoxic in vivo model, highlighting its promising neuroprotective properties to rescue acute brain lesions.

Immunology primer for neurosurgeons and neurologists part 2: Innate brain immunity

Over the past several decades we have learned a great deal about microglia and innate brain immunity. While microglia are the principle innate immune cells, other cell types also play a role, including invading macrophages, astrocytes, neurons, and endothelial cells. The fastest reacting cell is the microglia and despite its name, resting microglia (also called ramified microglia) are in fact quite active. Motion photomicrographs demonstrate a constant movement of ramified microglial foot processes, which appear to be testing the microenvironment for dangerous alteration in extracellular fluid content. These foot processes, in particular, interact with synapses and play a role in synaptic function. In event of excitatory overactivity, these foot processes can strip selected synapses, thus reducing activation states as a neuroprotective mechanism. They can also clear extracellular glutamate so as to reduce the risk of excitotoxicity. Microglia also appear to have a number of activation phenotypes, such as: (1) phagocytic, (2) neuroprotective and growth promoting, or (3) primarily neurodestructive. These innate immune cells can migrate a great distance under pathological conditions and appear to have anatomic specificity, meaning they can accumulate in specifically selected areas of the brain. There is some evidence that there are several types of microglia. Macrophage infiltration into the embryonic brain is the source of resident microglia and in adulthood macrophages can infiltrate the brain and are for the most part pathologically indistinguishable from resident microglia, but may react differently. Activation itself does not imply a destructive phenotype and can be mostly neuroprotective via phagocytosis of debris, neuron parts and dying cells and by the release of neurotrophins such as nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF). Evidence is accumulating that microglia undergo dynamic fluctuations in phenotype as the neuropathology evolves. For example, in the early stages of neurotrauma and stroke, microglia play a mostly neuroprotective role and only later switch to a neurodestructive mode. A great number of biological systems alter microglia function, including neurohormones, cannabinoids, other neurotransmitters, adenosine triphosphate (ATP), adenosine, and corticosteroids. One can appreciate that with aging many of these systems are altered by the aging process itself or by disease thus changing the sensitivity of the innate immune system.

Is there a causal link between inflammation and dementia?

Neuroinflammation is a constant event in Alzheimer's disease (AD), but the current knowledge is insufficient to state whether inflammation is a cause, a promoter, or simply a secondary phenomenon in this inexorably progressive ailment. In the current paper, we review research data showing that inflammation is not a prerequisite for onset of dementia, and, although it may worsen the course of the disease, recent evidence shows that chronic inhibition of inflammatory pathways is not necessarily beneficial for patients. Prospective clinical trials with anti-inflammatory drugs failed to stop disease progression, measurements of inflammatory markers in serum and cerebrospinal fluid of patients yielded contradictory results, and recent bench research proved undoubtedly that neuroinflammation has a protective side as well. Knockout animal models for TNFRs or ILRs do not seem to prevent the pathology or the cognitive decline, but quite the contrary. In AD, the therapeutic intervention on inflammatory pathways still has a research future, but its targets probably need reevaluation.

Triggers and effectors of oxidative stress at blood-brain barrier level: relevance for brain ageing and neurodegeneration

As fundamental research advances, it is becoming increasingly clear that a clinically expressed disease implies a mixture of intertwining molecular disturbances. Oxidative stress is one of such pathogenic pathways involved in virtually all central nervous system pathologies, infectious, inflammatory, or degenerative in nature. Since brain homeostasis largely depends on integrity of blood-brain barrier (BBB), many studies focused lately on BBB alteration in a wide spectrum of brain diseases. The proper two-way molecular transfer through BBB depends on several factors, including the functional status of its tight junction (TJ) complexes of proteins sealing neighbour endothelial cells. Although there is abundant experimental work showing that oxidative stress associates BBB permeability alteration, less is known about its implications, at molecular level, in TJ protein expression or TJ-related cell signalling. In this paper, oxidative stress is presented as a common pathway for different brain pathogenic mechanisms which lead to BBB dysregulation. We revise here oxidative-induced molecular mechanisms of BBB disruption and TJ protein expression alteration, in relation to ageing and neurodegeneration.

Cognitive dysfunction with aging and the role of inflammation

As the average lifespan continues to climb because of advances in medical care, there is a greater need to understand the factors that contribute to quality of life in the elderly. The capacity to live independently is highly significant in this regard, but is compromised by cognitive dysfunction. Aging is associated with decreases in cognitive function, including impairments in episodic memory and executive functioning. The prefrontal cortex appears to be particularly vulnerable to the effects of advancing age. Although the mechanism of age-related cognitive decline is not yet known, age-related inflammatory changes are likely to play a role. New insights from preclinical and clinical research may give rise to novel therapeutics which may have efficacy in slowing or preventing cognitive decline with advancing age.

Selective TNF inhibition for chronic stroke and traumatic brain injury: an observational study involving 629 consecutive patients treated with perispinal etanercept

BACKGROUND

Brain injury from stroke and traumatic brain injury (TBI) may result in a persistent neuroinflammatory response in the injury penumbra. This response may include microglial activation and excess levels of tumour necrosis factor (TNF). Previous experimental data suggest that etanercept, a selective TNF inhibitor, has the ability to ameliorate microglial activation and modulate the adverse synaptic effects of excess TNF. Perispinal administration may enhance etanercept delivery across the blood-CSF barrier.

OBJECTIVE

The objective of this study was to systematically examine the clinical response following perispinal administration of etanercept in a cohort of patients with chronic neurological dysfunction after stroke and TBI.

METHODS

After approval by an independent external institutional review board (IRB), a chart review of all patients with chronic neurological dysfunction following stroke or TBI who were treated open-label with perispinal etanercept (PSE) from November 1, 2010 to July 14, 2012 at a group medical practice was performed.

RESULTS

The treated cohort included 629 consecutive patients. Charts of 617 patients following stroke and 12 patients following TBI were reviewed. The mean age of the stroke patients was 65.8 years ± 13.15 (range 13-97). The mean interval between treatment with PSE and stroke was 42.0 ± 57.84 months (range 0.5-419); for TBI the mean interval was 115.2 ± 160.22 months (range 4-537). Statistically significant improvements in motor impairment, spasticity, sensory impairment, cognition, psychological/behavioural function, aphasia and pain were noted in the stroke group, with a wide variety of additional clinical improvements noted in individuals, such as reductions in pseudobulbar affect and urinary incontinence. Improvements in multiple domains were typical. Significant improvement was noted irrespective of the length of time before treatment was initiated; there was evidence of a strong treatment effect even in the subgroup of patients treated more than 10 years after stroke and TBI. In the TBI cohort, motor impairment and spasticity were statistically significantly reduced.

DISCUSSION

Irrespective of the methodological limitations, the present results provide clinical evidence that stroke and TBI may lead to a persistent and ongoing neuroinflammatory response in the brain that is amenable to therapeutic intervention by selective inhibition of TNF, even years after the acute injury.

CONCLUSION

Excess TNF contributes to chronic neurological, neuropsychiatric and clinical impairment after stroke and TBI. Perispinal administration of etanercept produces clinical improvement in patients with chronic neurological dysfunction following stroke and TBI. The therapeutic window extends beyond a decade after stroke and TBI. Randomized clinical trials will be necessary to further quantify and characterize the clinical response.

Brain abscesses complicating acute pneumococcal meningitis during etanercept therapy

Brain abscess formation as a sequelae of community-acquired pneumococcal meningitis is extremely rare, accounting for less than 1% of all meningitis complications. Although metastatic seeding from a distal peripheral septic focus has been observed, this phenomenon most commonly occurs in the context of ear, nose and throat infections, post-cranial neurosurgical procedures, traumatic open cranial injury, or immunosuppression. We present the case of a man, 61 years old, on etanercept therapy for ankylosing spondylitis who developed multiple brain abscesses as a complication of pneumococcal meningitis. We believe that the predisposition to this extremely rare complication of a particularly aggressive pneumococcal meningitis was most likely due to the underlying immunosuppression resulting from etanercept therapy. As far as we know, this case is the first report linking multiple brain abscess formation in a patient with community-acquired pneumococcal meningitis with etanercept therapy.

Early intervention with a small molecule inhibitor for tumor necrosis factor-α prevents cognitive deficits in a triple transgenic mouse model of Alzheimer's disease

BACKGROUND

Chronic neuroinflammation is an important component of Alzheimer's disease and could contribute to neuronal dysfunction, injury and loss that lead to disease progression. Multiple clinical studies implicate tumor necrosis factor-α as an inflammatory mediator of neurodegeneration in patients with Alzheimer's because of elevated levels of this cytokine in the cerebrospinal fluid, hippocampus and cortex. Current Alzheimer's disease interventions are symptomatic treatments with limited efficacy that do not address etiology. Thus, a critical need exists for novel treatments directed towards modifying the pathophysiology and progression.

METHODS

To investigate the effect of early immune modulation on neuroinflammation and cognitive outcome, we treated triple transgenic Alzheimer's disease mice (harboring PS1(M146V), APP(Swe), and tau(P301L) transgenes) with the small molecule tumor necrosis factor-α inhibitors, 3,6'-dithiothalidomide and thalidomide, beginning at four months of age. At this young age, mice do not exhibit plaque or tau pathology but do show mild intraneuronal amyloid beta protein staining and a robust increase in tumor necrosis factor-α. After 10 weeks of treatment, cognitive performance was assessed using radial arm maze and neuroinflammation was assessed using biochemical, stereological and flow cytometric endpoints.

RESULTS

3,6'-dithiothalidomide reduced tumor necrosis factor-α mRNA and protein levels in the brain and improved working memory performance and the ratio of resting to reactive microglia in the hippocampus of triple transgenic mice. In comparison to non-transgenic controls, triple transgenic Alzheimer's disease mice had increased total numbers of infiltrating peripheral monomyelocytic/granulocytic leukocytes with enhanced intracytoplasmic tumor necrosis factor-α, which was reduced after treatment with 3,6'-dithiothalidomide.

CONCLUSIONS

These results suggest that modulation of tumor necrosis factor-α with small molecule inhibitors is safe and effective with potential for the long-term prevention and treatment of Alzheimer's disease.

Curcumin requires tumor necrosis factor α signaling to alleviate cognitive impairment elicited by lipopolysaccharide

A decline in cognitive ability is a typical feature of the normal aging process, and of neurodegenerative disorders such as Alzheimer's, Parkinson's and Huntington's diseases. Although their etiologies differ, all of these disorders involve local activation of innate immune pathways and associated inflammatory cytokines. However, clinical trials of anti-inflammatory agents in neurodegenerative disorders have been disappointing, and it is therefore necessary to better understand the complex roles of the inflammatory process in neurological dysfunction. The dietary phytochemical curcumin can exert anti-inflammatory, antioxidant and neuroprotective actions. Here we provide evidence that curcumin ameliorates cognitive deficits associated with activation of the innate immune response by mechanisms requiring functional tumor necrosis factor α receptor 2 (TNFR2) signaling. In vivo, the ability of curcumin to counteract hippocampus-dependent spatial memory deficits, to stimulate neuroprotective mechanisms such as upregulation of BDNF, to decrease glutaminase levels, and to modulate N-methyl-D-aspartate receptor levels was absent in mice lacking functional TNFRs. Curcumin treatment protected cultured neurons against glutamate-induced excitotoxicity by a mechanism requiring TNFR2 activation. Our results suggest the possibility that therapeutic approaches against cognitive decline designed to selectively enhance TNFR2 signaling are likely to be more beneficial than the use of anti-inflammatory drugs per se.

Role of pro-inflammatory cytokines released from microglia in neurodegenerative diseases

Microglia are activated in response to a number of different pathological states within the CNS including injury, ischemia, and infection. Microglial activation results in their production of pro-inflammatory cytokines such as IL-1, IL-6, and TNF-α. While release of these factors is typically intended to prevent further damage to CNS tissue, they may also be toxic to neurons and other glial cells. Mounting evidence indicates that chronic microglial activation may also contribute to the development and progression of neurodegenerative disorders. Unfortunately, determining the role of pro-inflammatory cytokines in these disorders has been complicated by their dual roles in neuroprotection and neurodegeneration. The purpose of this review is to summarize current understanding of the involvement of cytokines in neurodegenerative disorders and their potential signaling mechanisms in this context. Taken together, recent findings suggest that microglial activation and pro-inflammatory cytokines merit interest as targets in the treatment of neurodegenerative disorders.