Intrathecal Chemokine Synthesis in Mild Cognitive Impairment and Alzheimer Disease

Decreased IL-8 levels in CSF and serum of AD patients and negative correlation of MMSE and IL-1β

Background

It is widely accepted that neuroinflammatory processes play an important role in the pathogenesis of Alzheimer’s disease (AD) and high levels of cytokines and chemokines are detected around Aβ plaques.

Methods

As neuroinflammation is involved in the development and progression of AD, we measured the pro-inflammatory cytokines interleukin 1β (IL-1β), IL-8 and tumor necrosis factor α (TNF-α) in serum and cerebrospinal fluid (CSF) samples from 45 AD patients and 53 age-matched control subjects using a highly sensitive multiplex electrochemiluminescence assay. To address the association with disease progression we correlated cognitive status with cytokine levels.

Results

CSF as well as serum IL-8 levels were found to be significantly lower in AD patients than in controls (p = 0.02). A statistically significant inverse correlation was observed between the CSF level of IL-1β and the MMSE score (r_s = -0.03, p = 0.02). We therefore stratified the AD patients by their MMSE scores into three equal groups and found that in the AD group with the most severe cognitive impairment CSF-IL-1β was significantly increased compared to age-matched controls (p < 0.05), whereas in the other investigated groups the increase was not statistically significant.

Conclusion

Our results confirm data suggesting that cytokine alterations are involved in AD pathogenesis and may be helpful as a biomarker for monitoring disease progression.

Electronic supplementary material

The online version of this article (doi:10.1186/s12883-016-0707-z) contains supplementary material, which is available to authorized users.

Alpha-Synuclein Proteins Promote Pro-Inflammatory Cascades in Microglia: Stronger Effects of the A53T Mutant

Parkinson’s disease (PD) is histologically described by the deposition of α-synuclein, whose accumulation in Lewy bodies causes dopaminergic neuronal death. Although most of PD cases are sporadic, point mutations of the gene encoding the α-synuclein protein cause inherited forms of PD. There are currently six known point mutations that result in familial PD. Oxidative stress and neuroinflammation have also been described as early events associated with dopaminergic neuronal degeneration in PD. Though it is known that microglia are activated by wild-type α-synuclein, little is known about its mutated forms and the signaling cascades responsible for this microglial activation. The present study was designed to investigate consequences of wild-type and mutant α-synuclein (A53T, A30P and E46K) exposure on microglial reactivity. Interestingly, we described that α-synuclein-induced microglial reactivity appeared to be peptide-dependent. Indeed, the A53T protein activated more strongly microglia than the wild-type α-synuclein and other mutants. This A53T-induced microglial reactivity mechanism was found to depend on phosphorylation mechanisms mediated by MAPKs and on successive NFkB/AP-1/Nrf2 pathways activation. These results suggest that the microgliosis intensity during PD might depend on the type of α-synuclein protein implicated. Indeed, mutated forms are more potent microglial stimulators than wild-type α-synuclein. Based on these data, anti-inflammatory and antioxidant therapeutic strategies may be valid in order to reduce microgliosis but also to subsequently slow down PD progression, especially in familial cases.

Interleukin-8 gene polymorphism -251T>A contributes to Alzheimer's disease susceptibility

BACKGROUND

Published association studies have investigated the correlation between interleukin-8 (IL-8) gene polymorphism -251T>A and susceptibility to Alzheimer's disease (AD); however, the results are conflicting. Thus, we conducted the meta-analysis to reassess the effect of IL-8 gene -251T>A variant on the risk of AD.

METHODS

Relevant studies regarding this association were electronically searched and identified from the PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, and the Chinese Biomedicine Database. The odds ratios (ORs) with the corresponding 95% confidence intervals (95% CIs) were pooled to calculate the strength of this association.

RESULTS

Nine studies with a total of 1406 cases and 2152 controls were included in the meta-analysis. Overall, a significant association of IL-8 gene -251T>A polymorphism with increased risk of AD was observed in several genetic models (allele, A vs T: OR=1.32, 95%CI=1.16-1.50; homozygous, AA vs TT: OR=1.70, 95%CI=1.21-2.21; heterozygous, TA vs TT: OR=1.37, 95%CI=1.12-1.69; recessive, AA vs TA+TT: OR=1.40, 95%CI=1.12-1.75). Similarly, such association was also revealed both in Asian and European populations in the subgroup analysis by ethnicity.

CONCLUSION

The current study suggested that IL-8 gene polymorphism -251T>A may contribute to the susceptibility to AD.

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.

Biomarkers in Sporadic and Familial Alzheimer's Disease

Most forms of Alzheimer's disease (AD) are sporadic (sAD) or inherited in a non-Mendelian fashion, and less than 1% of cases are autosomal-dominant. Forms of sAD do not exhibit familial aggregation and are characterized by complex genetic and environmental interactions. Recently, the expansion of genomic methodologies, in association with substantially larger combined cohorts, has resulted in various genome-wide association studies that have identified several novel genetic associations of AD. Currently, the most effective methods for establishing the diagnosis of AD are defined by multi-modal pathways, starting with clinical and neuropsychological assessment, cerebrospinal fluid (CSF) analysis, and brain-imaging procedures, all of which have significant cost- and access-to-care barriers. Consequently, research efforts have focused on the development and validation of non-invasive and generalizable blood-based biomarkers. Among the modalities conceptualized by the systems biology paradigm and utilized in the "exploratory biomarker discovery arena", proteome analysis has received the most attention. However, metabolomics, lipidomics, transcriptomics, and epigenomics have recently become key modalities in the search for AD biomarkers. Interestingly, biomarker changes for familial AD (fAD), in many but not all cases, seem similar to those for sAD. The integration of neurogenetics with systems biology/physiology-based strategies and high-throughput technologies for molecular profiling is expected to help identify the causes, mechanisms, and biomarkers associated with the various forms of AD. Moreover, in order to hypothesize the dynamic trajectories of biomarkers through disease stages and elucidate the mechanisms of biomarker alterations, updated and more sophisticated theoretical models have been proposed for both sAD and fAD.

sTREM2 cerebrospinal fluid levels are a potential biomarker for microglia activity in early-stage Alzheimer's disease and associate with neuronal injury markers

TREM2 is an innate immune receptor expressed on the surface of microglia. Loss‐of‐function mutations of TREM2 are associated with increased risk of Alzheimer's disease (AD). TREM2 is a type‐1 protein with an ectodomain that is proteolytically cleaved and released into the extracellular space as a soluble variant (sTREM2), which can be measured in the cerebrospinal fluid (CSF). In this cross‐sectional multicenter study, we investigated whether CSF levels of sTREM2 are changed during the clinical course of AD, and in cognitively normal individuals with suspected non‐AD pathology (SNAP). CSF sTREM2 levels were higher in mild cognitive impairment due to AD than in all other AD groups and controls. SNAP individuals also had significantly increased CSF sTREM2 compared to controls. Moreover, increased CSF sTREM2 levels were associated with higher CSF total tau and phospho‐tau_181P, which are markers of neuronal degeneration and tau pathology. Our data demonstrate that CSF sTREM2 levels are increased in the early symptomatic phase of AD, probably reflecting a corresponding change of the microglia activation status in response to neuronal degeneration.

Increased peripheral inflammation in asymptomatic leucine-rich repeat kinase 2 mutation carriers

BACKGROUND

We aimed to determine if peripheral or central inflammatory cytokines are altered in healthy subjects carrying a leucine-rich repeat kinase 2 (LRRK2) G2019S mutation, and thus genetically at risk of Parkinson's disease (PD). We also aimed to identify differences in inflammatory cytokines between LRRK2 G2019S-associated and idiopathic PD once the disease manifests.

METHODS

Participants were genetically screened and phenotyped, and biological samples were collected and stored by the Michael J. Fox Foundation LRRK2 Cohort Consortium. Serum samples and matching clinical data were obtained from 71 asymptomatic LRRK2 G2019S mutation carriers (CSF n = 25), 75 neurologically normal controls (CSF n = 22), 75 idiopathic PD patients (CSF n = 29), and 76 PD patients with a LRRK2 G2019S mutation (CSF n = 20). Inflammatory cytokines were measured using multiplex enzyme-linked immunosorbent assays.

RESULTS

Serum levels of interleukin 1 beta could discriminate asymptomatic LRRK2 G2019S mutation carriers from controls, with a high inflammatory subgroup of carriers identified. This subgroup was significantly higher in a number of PD-implicated pro-inflammatory cytokines. Once PD had manifest, LRRK2 G2019S patients were discriminated from idiopathic PD by higher serum platelet-derived growth factor, and higher CSF vascular endothelial growth factor and interleukin 8.

CONCLUSIONS

The results suggest that peripheral inflammation is higher in a percentage of subjects carrying the LRRK2 G2019S mutation. Replication and longitudinal follow-up is required to determine whether the increased peripheral cytokines can predict clinical PD. Importantly, these biological changes were observed prior to the clinical manifestations thought to herald PD. © 2016 International Parkinson and Movement Disorder Society.

Insight into the Molecular Imaging of Alzheimer's Disease

Alzheimer's disease is a complex neurodegenerative disease affecting millions of individuals worldwide. Earlier it was diagnosed only via clinical assessments and confirmed by postmortem brain histopathology. The development of validated biomarkers for Alzheimer's disease has given impetus to improve diagnostics and accelerate the development of new therapies. Functional imaging like positron emission tomography (PET), single photon emission computed tomography (SPECT), functional magnetic resonance imaging (fMRI), and proton magnetic resonance spectroscopy provides a means of detecting and characterising the regional changes in brain blood flow, metabolism, and receptor binding sites that are associated with Alzheimer's disease. Multimodal neuroimaging techniques have indicated changes in brain structure and metabolic activity, and an array of neurochemical variations that are associated with neurodegenerative diseases. Radiotracer-based PET and SPECT potentially provide sensitive, accurate methods for the early detection of disease. This paper presents a review of neuroimaging modalities like PET, SPECT, and selected imaging biomarkers/tracers used for the early diagnosis of AD. Neuroimaging with such biomarkers and tracers could achieve a much higher diagnostic accuracy for AD and related disorders in the future.

The contribution of neuroinflammation to amyloid toxicity in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease and the most common cause of dementia. Deposition of amyloid-β (Aβ) remains a hallmark feature of the disease, yet the precise mechanism(s) by which this peptide induces neurotoxicity remain unknown. Neuroinflammation has long been implicated in AD pathology, yet its contribution to disease progression is still not understood. Recent evidence suggests that various Aβ complexes interact with microglial and astrocytic expressed pattern recognition receptors that initiate innate immunity. This process involves secretion of pro-inflammatory cytokines, chemokines and generation of reactive oxygen species that, in excess, drive a dysregulated immune response that contributes to neurodegeneration. The mechanisms by which a neuroinflammatory response can influence Aβ production, aggregation and eventual clearance are now becoming key areas where future therapeutic intervention may slow progression of AD. This review will focus on evidence supporting the combined neuroinflammatory-amyloid hypothesis for pathogenesis of AD, describing the key cell types, pathways and mediators involved. Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the leading cause of dementia worldwide. Deposition of intracellular plaques containing amyloid-beta (Aβ) is a hallmark proteinopathy of the disease yet the precise mechanisms by which this peptide induces neurotoxicity remains unknown. A neuroinflammatory response involving polarized microglial activity, enhanced astrocyte reactivity and elevated pro-inflammatory cytokine and chemokine load has long been implicated in AD and proposed to facilitate neurodegeneration. In this issue we discuss key receptor systems of innate immunity that detect Aβ, drive pro-inflammatory cytokine and chemokine production and influence Aβ aggregation and clearance. Evidence summarized in this review supports the combined neuroinflammatory-amyloid hypothesis for pathogenesis of AD and highlights the potential of immunomodulatory agents as potential future therapies for AD patients.

Endoplasmic reticulum stress-regulated CXCR3 pathway mediates inflammation and neuronal injury in acute glaucoma

Acute glaucoma is a leading cause of irreversible blindness in East Asia. The mechanisms underlying retinal neuronal injury induced by a sudden rise in intraocular pressure (IOP) remain obscure. Here we demonstrate that the activation of CXCL10/CXCR3 axis, which mediates the recruitment and activation of inflammatory cells, has a critical role in a mouse model of acute glaucoma. The mRNA and protein expression levels of CXCL10 and CXCR3 were significantly increased after IOP-induced retinal ischemia. Blockade of the CXCR3 pathway by deleting CXCR3 gene significantly attenuated ischemic injury-induced upregulation of inflammatory molecules (interleukin-1β and E-selectin), inhibited the recruitment of microglia/monocyte to the superficial retina, reduced peroxynitrite formation, and prevented the loss of neurons within the ganglion cell layer. In contrast, intravitreal delivery of CXCL10 increased leukocyte recruitment and retinal cell apoptosis. Inhibition of endoplasmic reticulum (ER) stress with chemical chaperones partially blocked ischemic injury-induced CXCL10 upregulation, whereas induction of ER stress with tunicamycin enhanced CXCL10 expression in retina and primary retinal ganglion cells. Interestingly, deleting CXCR3 attenuated ER stress-induced retinal cell death. In conclusion, these results indicate that ER stress-medicated activation of CXCL10/CXCR3 pathway has an important role in retinal inflammation and neuronal injury after high IOP-induced ischemia.

Inflammatory molecules in Frontotemporal Dementia: cerebrospinal fluid signature of progranulin mutation carriers

Mutations in progranulin gene (GRN) are one of the major causes of autosomal dominant Frontotemporal Lobar Degeneration (FTLD). Progranulin displays anti-inflammatory properties and is likely a ligand of Tumor Necrosis Factor (TNF) receptor 2, expressed on microglia. A few cytokines and chemokines are altered in cerebrospinal fluid (CSF) from patients with sporadic FTLD, whereas no information is available in familial cases. We evaluated, through BioPlex, levels of 27 inflammatory molecules, including cytokines, chemokines, and related receptors, in CSF and matched serum, from FTLD patients carrying GRN mutations as compared with sporadic FTLD with no GRN mutations and controls. Mean±SD Monocyte Chemoattractant Protein-1 (MCP-1) levels were significantly increased in CSF from sporadic FTLD patients as compared with controls (334.27±151.5 versus 159.7±49pg/ml; P⩽0.05). In GRN mutation carriers versus controls, CSF levels of MCP-1 were unchanged, whereas Interferon-γ-inducible protein-10 (IP-10) levels were increased (809.17±240.0 versus 436.61±202.5pg/ml; P=0.012). In the same group, TNFα and Interleukin (IL)-15 levels were decreased (3.18±1.41 versus 35.68±30.5pg/ml; P=0.013 and 9.34±5.54 versus 19.15±10.03pg/ml; P=0.023, respectively). Conversely, Regulated upon Activation, Normal T-cell Expressed, and Secreted (RANTES) levels were decreased in patients, with or without mutations, as compared with controls (4.63±3.30 and 2.58±20 versus 87.57±70pg/ml, respectively; P<0.05). Moreover, IP-10, IL-15 and RANTES CSF levels were not influenced by age, whereas MCP-1 levels increased with age (ρ=0.48; P=0.007). In conclusion, inflammatory de-regulation was observed in both sporadic FTLD and GRN carriers compared to controls, with a specific inflammatory profile for the latter group.

Interferon-stimulated gene (ISG) 60, as well as ISG56 and ISG54, positively regulates TLR3/IFN-β/STAT1 axis in U373MG human astrocytoma cells

Treatment of cells with interferons (IFNs) induces the phosphorylation of signal transducer and activator of transcription 1 (STAT1), leading to the expression of hundreds of IFN-stimulated genes (ISGs). ISGs exert various antiviral and pro-inflammatory reactions. We have previously reported that ISG56 and ISG54 are induced by polyinosinic-polycytidylic acid (poly IC), an authentic agonist for Toll-like receptor 3 (TLR3), in U373MG human astrocytoma cells. ISG56 and ISG54 are also named as IFN-induced proteins with tetratricopeptide repeats (IFIT) 1 and IFIT2, respectively. In the present study, we demonstrated that poly IC induces the expression of ISG60, also named as IFIT3, in U373MG cells. RNA interference experiments showed that the induction of ISG60 by poly IC was mediated by TLR3, IFN-β, ISG56 and ISG54, whereas ISG60 is involved in poly IC-induced expression of ISG56, ISG54 and a chemokine CXCL10. The level of phosphorylated STAT1 was enhanced by poly IC, and it was inhibited by knockdown of ISG56, ISG54 or ISG60. These results suggest that there is a positive feedback loop between phosphorylated STAT1 and these ISGs.

The Inflammatory Marker YKL-40 Is Elevated in Cerebrospinal Fluid from Patients with Alzheimer's but Not Parkinson's Disease or Dementia with Lewy Bodies

A major difference in the revised diagnostic criteria for Alzheimer’s disease (AD) is the incorporation of biomarkers to support a clinical diagnosis and allow the identification of preclinical AD due to AD neuropathological processes. However, AD-specific fluid biomarkers which specifically distinguish clinical AD dementia from other dementia disorders are still missing. Here we aimed to evaluate the disease-specificity of increased YKL-40 levels in cerebrospinal fluid (CSF) from AD patients with mild to moderate dementia (n = 49) versus Parkinson’s disease (PD) (n = 61) and dementia with Lewy bodies (DLB) patients (n = 36), and non-demented controls (n = 44). Second we aimed to investigate whether altered YKL-40 levels are associated with CSF levels of other inflammation-associated molecules. When correcting for age, AD patients exhibited 21.3%, 27.7% and 38.8% higher YKL-40 levels compared to non-demented controls (p = 0.0283), DLB (p = 0.0027) and PD patients (p<0.0001). The AD-associated increase in YKL-40 was not associated with CSF P-tau, T-tau or Aβ42. No relationship between increased YKL-40 and levels of the astrocytic marker glial-fibrillary acidic protein (GFAP), interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1) and interferon gamma-induced protein 10 (IP-10) could be identified. Our results confirm previous reports of an age-associated increased in CSF YKL-40 levels and further demonstrate increased CSF YKL-40 in AD patients versus non-demented controls and patients with DLB or PD. The increase in YKL-40 levels in the AD patients was unrelated to the established CSF AD biomarkers and the inflammatory markers GFAP, MCP-1, IP-10 and IL-8, proposing YKL-40 as a marker of yet to be identified AD-related pathological processes.

Pharmacological antagonism of interleukin-8 receptor CXCR2 inhibits inflammatory reactivity and is neuroprotective in an animal model of Alzheimer's disease

Background

The chemokine interleukin-8 (IL-8) and its receptor CXCR2 contribute to chemotactic responses in Alzheimer’s disease (AD); however, properties of the ligand and receptor have not been characterized in animal models of disease. The primary aim of our study was to examine effects of pharmacological antagonism of CXCR2 as a strategy to inhibit receptor-mediated inflammatory reactivity and enhance neuronal viability in animals receiving intrahippocampal injection of amyloid-beta (Aβ_1–42).

Methods

In vivo studies used an animal model of Alzheimer’s disease incorporating injection of full-length Aβ_1–42 into rat hippocampus. Immunohistochemical staining of rat brain was used to measure microgliosis, astrogliosis, neuronal viability, and oxidative stress. Western blot and Reverse Transcription PCR (RT-PCR) were used to determine levels of CXCR2 in animal tissue with the latter also used to determine expression of pro-inflammatory mediators. Immunostaining of human AD and non-demented (ND) tissue was also undertaken.

Results

We initially determined that in the human brain, AD relative to ND tissue exhibited marked increases in expression of CXCR2 with cell-specific receptor expression prominent in microglia. In Aβ_1–42-injected rat brain, CXCR2 and IL-8 showed time-dependent increases in expression, concomitant with enhanced gliosis, relative to controls phosphate-buffered saline (PBS) or reverse peptide Aβ_42–1 injection. Administration of the competitive CXCR2 antagonist SB332235 to peptide-injected rats significantly reduced expression of CXCR2 and microgliosis, with astrogliosis unchanged. Double staining studies demonstrated localization of CXCR2 and microglial immunoreactivity nearby deposits of Aβ_1–42 with SB332235 effective in inhibiting receptor expression and microgliosis. The numbers of neurons in granule cell layer (GCL) were reduced in rats receiving Aβ_1–42, compared with PBS, with administration of SB332235 to peptide-injected animals conferring neuroprotection. Oxidative stress was indicated in the animal model since both 4-hydroxynonenal (4-HNE) and hydroethidine (HEt) were markedly elevated in Aβ_1–42 vs PBS-injected rat brain and diminished with SB332235 treatment.

Conclusion

Overall, the findings suggest critical roles for CXCR2-dependent inflammatory responses in an AD animal model with pharmacological modulation of the receptor effective in inhibiting inflammatory reactivity and conferring neuroprotection against oxidative damage.

The complex contribution of chemokines to neuroinflammation: switching from beneficial to detrimental effects

Inflammation is an innate mechanism that defends organisms against harmful stimuli. Inflammation leads to the production and secretion of proinflammatory mediators that activate and recruit immune cells to damaged tissues, including the brain, to resolve the cause of inflammation. In the central nervous system, inflammation is referred to as neuroinflammation, which occurs in various pathological conditions of the brain. The primary role of neuroinflammation is to protect the brain. However, prolonged and/or inappropriate inflammation can be harmful for the brain, from individual cells to the whole tissue. This review focuses on a particular type of inflammatory mediator, chemokines, and describes their complex effects both under physiological and pathophysiological conditions of the brain. The clinical relevance of the multiple characters of chemokines is highlighted with respect to acute and chronic inflammation of the brain, including their actions in stroke and Alzheimer's disease, respectively.

The role of chemokine C-C motif ligand 2 genotype and cerebrospinal fluid chemokine C-C motif ligand 2 in neurocognition among HIV-infected patients

OBJECTIVES

We examined interrelationships between chemokine C-C motif ligand 2 (CCL2) genotype and expression of inflammatory markers in the cerebrospinal fluid (CSF), plasma viral load, CD4 cell count and neurocognitive functioning among HIV-infected adults. We hypothesized that HIV-positive carriers of the 'risk' CCL2 -2578G allele, caused by a single nucleotide polymorphism (SNP) at rs1024611, would have a higher concentration of CCL2 in CSF, and that CSF CCL2 would be associated with both higher concentrations of other proinflammatory markers in CSF and worse neurocognitive functioning.

DESIGN

A cross-sectional study of 145 HIV-infected individuals enrolled in the National NeuroAIDS Tissue Consortium cohort for whom genotyping, CSF and neurocognitive data were available.

METHODS

Genomic DNA was extracted from peripheral blood mononuclear cells and/or frozen tissue specimens. CSF levels of CCL2, interleukin (IL)-2, IL-6, tumour necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), soluble tumor necrosis factor receptor 2, sIL-6Rα, sIL-2, sCD14 and B-cell activating factor were quantified. Neurocognitive functioning was measured using a comprehensive battery of neuropsychological tests.

RESULTS

Carriers of the CCL2 -2578G allele had a significantly higher concentration of CCL2 in CSF. CSF CCL2 level was positively and significantly associated with other CSF neuroinflammatory markers and worse cognitive functioning. There was a significant association between genotype and plasma viral load, such that carriers of the CCL2 -2578G allele with high viral load expressed greater levels of CCL2 and had higher neurocognitive deficit scores than other genotype/viral load groups.

CONCLUSION

Individuals with the CCL2 -2578G allele had higher levels of CCL2 in CSF, which was associated with increased pro-inflammatory markers in CSF and worse neurocognitive functioning. The results highlight the potential role of intermediate phenotypes in studies of genotype and cognition.

Cerebrospinal fluid biomarkers of neurovascular dysfunction in mild dementia and Alzheimer's disease

Alzheimer's disease (AD) is the most common form of age-related dementias. In addition to genetics, environment, and lifestyle, growing evidence supports vascular contributions to dementias including dementia because of AD. Alzheimer's disease affects multiple cell types within the neurovascular unit (NVU), including brain vascular cells (endothelial cells, pericytes, and vascular smooth muscle cells), glial cells (astrocytes and microglia), and neurons. Thus, identifying and integrating biomarkers of the NVU cell-specific responses and injury with established AD biomarkers, amyloid-β (Aβ) and tau, has a potential to contribute to better understanding of the disease process in dementias including AD. Here, we discuss the existing literature on cerebrospinal fluid biomarkers of the NVU cell-specific responses during early stages of dementia and AD. We suggest that the clinical usefulness of established AD biomarkers, Aβ and tau, could be further improved by developing an algorithm that will incorporate biomarkers of the NVU cell-specific responses and injury. Such biomarker algorithm could aid in early detection and intervention as well as identify novel treatment targets to delay disease onset, slow progression, and/or prevent AD.

Ebola: translational science considerations

We are currently in the midst of the most aggressive and fulminating outbreak of Ebola-related disease, commonly referred to as "Ebola", ever recorded. In less than a year, the Ebola virus (EBOV, Zaire ebolavirus species) has infected over 10,000 people, indiscriminately of gender or age, with a fatality rate of about 50%. Whereas at its onset this Ebola outbreak was limited to three countries in West Africa (Guinea, where it was first reported in late March 2014, Liberia, where it has been most rampant in its capital city, Monrovia and other metropolitan cities, and Sierra Leone), cases were later reported in Nigeria, Mali and Senegal, as well as in Western Europe (i.e., Madrid, Spain) and the US (i.e., Dallas, Texas; New York City) by late October 2014. World and US health agencies declared that the current Ebola virus disease (EVD) outbreak has a strong likelihood of growing exponentially across the world before an effective vaccine, treatment or cure can be developed, tested, validated and distributed widely. In the meantime, the spread of the disease may rapidly evolve from an epidemics to a full-blown pandemic. The scientific and healthcare communities actively research and define an emerging kaleidoscope of knowledge about critical translational research parameters, including the virology of EBOV, the molecular biomarkers of the pathological manifestations of EVD, putative central nervous system involvement in EVD, and the cellular immune surveillance to EBOV, patient-centered anthropological and societal parameters of EVD, as well as translational effectiveness about novel putative patient-targeted vaccine and pharmaceutical interventions, which hold strong promise, if not hope, to curb this and future Ebola outbreaks. This work reviews and discusses the principal known facts about EBOV and EVD, and certain among the most interesting ongoing or future avenues of research in the field, including vaccination programs for the wild animal vectors of the virus and the disease from global translational science perspective.

Activation of the nuclear receptor PPARδ is neuroprotective in a transgenic mouse model of Alzheimer's disease through inhibition of inflammation

Background

Alzheimer’s disease (AD) is a multifactorial disorder associated with the accumulation of soluble forms of beta-amyloid (Aβ) and its subsequent deposition into plaques. One of the major contributors to neuronal death is chronic and uncontrolled inflammatory activation of microglial cells around the plaques and their secretion of neurotoxic molecules. A shift in microglial activation towards a phagocytic phenotype has been proposed to confer benefit in models of AD. Peroxisome proliferator activator receptor δ (PPARδ) is a transcription factor with potent anti-inflammatory activation properties and PPARδ agonism leads to reduction in brain Aβ levels in 5XFAD mice. This study was carried out to elucidate the involvement of microglial activation in the PPARδ-mediated reduction of Aβ burden and subsequent outcome to neuronal survival in a 5XFAD mouse model of AD.

Methods

5XFAD mice were orally treated with the PPARδ agonist GW0742 for 2 weeks. The brain Aβ load, glial activation, and neuronal survival were assessed by immunohistochemistry and quantitative PCR. In addition, the ability of GW0742 to prevent direct neuronal death as well as inflammation-induced neuron death was analyzed in vitro.

Results

Our results show for the first time that a short treatment period of 5XFAD mice was effective in reducing the parenchymal Aβ load without affecting the levels of intraneuronal Aβ. This was concomitant with a decrease in overall microglial activation and reduction in proinflammatory mediators. Instead, microglial immunoreactivity around Aβ deposits was increased. Importantly, the reduction in the proinflammatory milieu elicited by GW0742 treatment resulted in attenuation of neuronal loss in vivo in the subiculum of 5XFAD mice. In addition, whereas GW0742 failed to protect primary neurons against glutamate-induced cell death, it prevented inflammation-induced neuronal death in microglia-neuron co-cultures in vitro.

Conclusions

This study demonstrates that GW0742 treatment has a prominent anti-inflammatory effect in 5XFAD mice and suggests that PPARδ agonists may have therapeutic utility in treating AD.

Desferrioxamine, an iron chelator, inhibits CXCL10 expression induced by polyinosinic-polycytidylic acid in U373MG human astrocytoma cells

Although iron is essential in physiological processes, accumulation of iron in central nervous system is associated with various neurological diseases including Alzheimer's disease and Parkinson's disease. Innate immune reactions are involved in the pathogenesis of those diseases, but roles of iron in innate immunity are not known well. In the present study, pretreatment of U373MG human astrocytoma cells with an iron chelator desferrioxamine (DFX) inhibited the expression of CXCL10 induced by a Toll-like receptor 3 (TLR3) agonist polyinosinic-polycytidylic acid (poly IC). Induction of interferon-β (IFN-β) was not affected, but phosphorylation of signal transducer and transcription 1 (STAT1) was decreased by DFX. We have previously reported that various IFN-stimulated genes (ISGs) are involved in CXCL10 induction by poly IC. Pretreatment with DFX also decreased the expression of these ISGs. Pretreatment of cells with FeSO4 counteracted inhibitory effects of DFX on ISG56, retinoic acid-inducible gene-I (RIG-I), CXCL10 and phosphorylation of STAT1. These results suggest that iron may positively regulate STAT1 phosphorylation and following signaling to express ISG56, RIG-I and CXCL10 in U373MG cells treated with poly IC. Iron may contribute to innate immune and inflammatory reactions elicited by the TLR3 signaling in astrocytes, and may play an important role in neuroinflammatory diseases.

Chlamydia pneumoniae infection of monocytes in vitro stimulates innate and adaptive immune responses relevant to those in Alzheimer's disease

Background

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder in which infection with Chlamydia pneumoniae (Cpn) has been associated. Cpn is an obligate intracellular respiratory pathogen that may enter the central nervous system (CNS) following infection and trafficking of monocytes through the blood-brain barrier. Following this entry, these cells may secrete pro-inflammatory cytokines and chemokines that have been identified in the AD brain, which have been thought to contribute to AD neurodegeneration. The objectives of this work were: (i) to determine if Cpn infection influences monocyte gene transcript expression at 48 hours post-infection and (ii) to analyze whether pro-inflammatory cytokines are produced and secreted from these cells over 24 to 120 hours post-infection.

Methods

Gene transcription was analyzed by RT-PCR using an innate and adaptive immunity microarray with 84 genes organized into 5 functional categories: inflammatory response, host defense against bacteria, antibacterial humoral response, septic shock, and cytokines, chemokines and their receptors. Statistical analysis of the results was performed using the Student's t-test. P-values ≤ 0.05 were considered to be significant. ELISA was performed on supernatants from uninfected and Cpn-infected THP1 monocytes followed by statistical analysis with ANOVA.

Results

When Cpn-infected THP1 human monocytes were compared to control uninfected monocytes at 48 hours post-infection, 17 genes were found to have a significant 4-fold or greater expression, and no gene expression was found to be down-regulated. Furthermore, cytokine secretion (IL-1β, IL-6, IL-8) appears to be maintained for an extended period of infection.

Conclusions

Utilizing RT-PCR and ELISA techniques, our data demonstrate that Cpn infection of THP1 human monocytes promotes an innate immune response and suggests a potential role in the initiation of inflammation in sporadic/late-onset Alzheimer’s disease.

Correlation between serum RANTES levels and the severity of Parkinson's disease

Inflammatory mediators may reflect a role of systemic inflammation in the neurodegenerative process of Parkinson's disease (PD). Interleukin-6 (IL-6) and chemokine ligand 5 (CCL5), also known as RANTES (regulated on activation, normal T cell expressed and secreted), have been implicated in neurodegenerative diseases including PD. Serum levels of RANTES and IL-6 of 78 consecutive PD patients and age-matched 80 controls were measured. Patients with PD had higher RANTES and IL-6 levels compared with the controls. We found that serum RANTES levels strongly correlated with Hoehn-Yahr score and disease duration in PD patients. This study indicated that patients with PD have an on-going systemic inflammatory profile where the elevated peripheral production of RANTES may play a role in the neurodegenerative process.

CXCR3 promotes plaque formation and behavioral deficits in an Alzheimer's disease model

Chemokines are important modulators of neuroinflammation and neurodegeneration. In the brains of Alzheimer's disease (AD) patients and in AD animal models, the chemokine CXCL10 is found in high concentrations, suggesting a pathogenic role for this chemokine and its receptor, CXCR3. Recent studies aimed at addressing the role of CXCR3 in neurological diseases indicate potent, but diverse, functions for CXCR3. Here, we examined the impact of CXCR3 in the amyloid precursor protein (APP)/presenilin 1 (PS1) transgenic mouse model of AD. We found that, compared with control APP/PSI animals, plaque burden and Aβ levels were strongly reduced in CXCR3-deficient APP/PS1 mice. Analysis of microglial phagocytosis in vitro and in vivo demonstrated that CXCR3 deficiency increased the microglial uptake of Aβ. Application of a CXCR3 antagonist increased microglial Aβ phagocytosis, which was associated with reduced TNF-α secretion. Moreover, in CXCR3-deficient APP/PS1 mice, microglia exhibited morphological activation and reduced plaque association, and brain tissue from APP/PS1 animals lacking CXCR3 had reduced concentrations of proinflammatory cytokines compared with controls. Further, loss of CXCR3 attenuated the behavioral deficits observed in APP/PS1 mice. Together, our data indicate that CXCR3 signaling mediates development of AD-like pathology in APP/PS1 mice and suggest that CXCR3 has potential as a therapeutic target for AD.

2',3'-cAMP, 3'-AMP, 2'-AMP and adenosine inhibit TNF-α and CXCL10 production from activated primary murine microglia via A2A receptors

BACKGROUND

Some cells, tissues and organs release 2',3'-cAMP (a positional isomer of 3',5'-cAMP) and convert extracellular 2',3'-cAMP to 2'-AMP plus 3'-AMP and convert these AMPs to adenosine (called the extracellular 2',3'-cAMP-adenosine pathway). Recent studies show that microglia have an extracellular 2',3'-cAMP-adenosine pathway. The goal of the present study was to investigate whether the extracellular 2',3'-cAMP-adenosine pathway could have functional consequences on the production of cytokines/chemokines by activated microglia.

METHODS

Experiments were conducted in cultures of primary murine microglia. In the first experiment, the effect of 2',3'-cAMP, 3'-AMP, 2'-AMP and adenosine on LPS-induced TNF-α and CXCL10 production was determined. In the next experiment, the first protocol was replicated but with the addition of 1,3-dipropyl-8-p-sulfophenylxanthine (DPSPX) (0.1 μM; antagonist of adenosine receptors). The last experiment compared the ability of 2-chloro-N(6)-cyclopentyladenosine (CCPA) (10 μM; selective A1 agonist), 5'-N-ethylcarboxamide adenosine (NECA) (10 μM; agonist for all adenosine receptor subtypes) and CGS21680 (10 μM; selective A2A agonist) to inhibit LPS-induced TNF-α and CXCL10 production.

RESULTS

(1) 2',3'-cAMP, 3'-AMP, 2'-AMP and adenosine similarly inhibited LPS-induced TNF-α and CXCL10 production; (2) DPSPX nearly eliminated the inhibitory effects of 2',3'-cAMP, 3'-AMP, 2'-AMP and adenosine on LPS-induced TNF-α and CXCL10 production; (3) CCPA did not affect LPS-induced TNF-α and CXCL10; (4) NECA and CGS21680 similarly inhibited LPS-induced TNF-α and CXCL10 production.

CONCLUSIONS

2',3'-cAMP and its metabolites (3'-AMP, 2'-AMP and adenosine) inhibit LPS-induced TNF-α and CXCL10 production via A2A-receptor activation. Adenosine and its precursors, via A2A receptors, likely suppress TNF-α and CXCL10 production by activated microglia in brain diseases.

Cognitive Status Correlates with CXCL10/IP-10 Levels in Parkinson's Disease

Cognitive impairment and depressive symptoms are of great interest in Parkinson's disease (PD), since they are very common and lead to increased disability with poor quality of life. Inflammatory mechanisms have been implicated in PD and its nonmotor symptoms. In the current pilot study, we aimed to evaluate plasma levels of chemokines in PD patients and to analyze the putative association of chemokines with depressive symptoms and cognitive performance. We hypothesized that higher chemokines levels are associated with worse cognitive performance and increased depressive symptoms in PD. For this purpose, 40 PD patients and 25 age- and gender-matched controls were subjected to a clinical evaluation including cognitive and mood tests. Peripheral blood was drawn and plasma levels of CCL2/MCP-1, CCL11/eotaxin, CCL24/eotaxin-2, and CXCL10/IP-10 were measured by enzyme-linked immunosorbent assay. PD patients and control individuals presented comparable plasma concentrations of all the evaluated chemokines. In PD patients, CXCL10/IP-10 plasma levels correlated positively with Hoehn and Yahr staging scale. In addition, the higher CXCL10/IP-10 levels, the worse performance on cognitive tests. Although there was no significant difference between PD patients and control individuals regarding chemokines levels, our preliminary results showed that CXCL10/IP-10 may be associated with cognitive status in PD.

CSF in Alzheimer's disease

Alzheimer's disease (AD) is a progressive brain amyloidosis that injures brain regions involved in memory consolidation and other cognitive functions. Neuropathologically, the disease is characterized by accumulation of a 42-amino acid protein called amyloid beta, and N-terminally truncated fragments thereof, in extracellular senile plaques together with intraneuronal inclusions of hyperphosphorylated tau protein in neurofibrillary tangles, and neuronal and axonal degeneration and loss. Clinical chemistry tests for these pathologies have been developed for use on cerebrospinal fluid samples. Here, we review what these markers have taught us on the disease process in AD and how they can be implemented in routine clinical chemistry. We also provide an update on new marker development and ongoing analytical standardization effort.

Increased astrocyte expression of IL-6 or CCL2 in transgenic mice alters levels of hippocampal and cerebellar proteins

Emerging research has identified that neuroimmune factors are produced by cells of the central nervous system (CNS) and play critical roles as regulators of CNS function, directors of neurodevelopment and responders to pathological processes. A wide range of neuroimmune factors are produced by CNS cells, primarily the glial cells, but the role of specific neuroimmune factors and their glial cell sources in CNS biology and pathology have yet to be fully elucidated. We have used transgenic mice that express elevated levels of a specific neuroimmune factor, the cytokine IL-6 or the chemokine CCL2, through genetic modification of astrocyte expression to identify targets of astrocyte produced IL-6 or CCL2 at the protein level. We found that in non-transgenic mice constitutive expression of IL-6 and CCL2 occurs in the two CNS regions studied, the hippocampus and cerebellum, as measured by ELISA. In the CCL2 transgenic mice elevated levels of CCL2 were evident in the hippocampus and cerebellum, whereas in the IL-6 transgenic mice, elevated levels of IL-6 were only evident in the cerebellum. Western blot analysis of the cellular and synaptic proteins in the hippocampus and cerebellum of the transgenic mice showed that the elevated levels of CCL2 or IL-6 resulted in alterations in the levels of specific proteins and that these actions differed for the two neuroimmune factors and for the two brain regions. These results are consistent with cell specific profiles of action for IL-6 and CCL2, actions that may be an important aspect of their respective roles in CNS physiology and pathophysiology.

The Potential Role of Chemokines in Alzheimer's Disease Pathogenesis

Alzheimer's disease (AD) is a neurodegenerative disorder and leading cause of dementia, which begins with impaired memory. The neuropathological hallmarks of AD include destructive alterations of neurons by neurofibrillary tangles, neuritic amyloid plaques, and neuroinflammatory process in the brain. Chemokines have a major role in inflammatory cell attraction and glial cell activation and/or modulation in the central nervous system. Moreover, the clinical and immunopathological evidence could show dual key role of chemokines in their pro- and anti-inflammatory properties in AD. However, their effects in neurodegeneration and/or neuroprotection remain an area of investigation. This review article provides an overview of characteristic, cellular source and activity of chemokines, and their roles in neuronal glial cell interaction in AD.

Increased Levels of Chitotriosidase and YKL-40 in Cerebrospinal Fluid from Patients with Alzheimer's Disease

Background

The cerebrospinal fluid (CSF) biomarkers total tau, abnormally phosphorylated tau and amyloid β 1-42 are strongly associated with Alzheimer's disease (AD). Apart from the pathologic hallmarks that these biomarkers represent, other processes such as inflammation and microglial activation are present in the brains of patients with AD. New biomarkers related to these processes could be valuable for the diagnosis and follow-up of AD patients and for the evaluation of inflammation-related pathologies.

Aim

The aim of this study was to evaluate the association of inflammatory CSF biomarkers with AD.

Methods

Twenty-five AD patients and 25 controls who had a pathological and normal CSF profile of the core AD biomarkers, respectively, were included in this study. CSF levels of chitotriosidase, YKL-40 (also known as chitinase-3-like protein 1) and monocyte chemoattractant protein-1 (MCP-1) were quantified and the levels compared between the groups.

Results

AD patients had increased CSF levels of chitotriosidase and YKL-40 (both approximately twice higher than in controls), while the levels of MCP-1 were similar in the AD and control groups.

Conclusion

The results indicate that chitotriosidase and YKL-40 may be helpful for the evaluation of cerebral inflammatory activity in AD patients.

Cerebrospinal fluid monocyte chemoattractant protein-1 in alcoholics: support for a neuroinflammatory model of chronic alcoholism

BACKGROUND

Liver inflammation in alcoholism has been hypothesized to influence the development of a neuroinflammatory process in the brain characterized by neurodegeneration and altered cognitive function. Monocyte chemoattractant protein-1/chemokine (C-C motif) ligand 2 (MCP-1/CCL2) elevations have been noted in the alcoholic brain at autopsy and may have a role in this process.

METHODS

We studied cerebrospinal fluid (CSF) levels of MCP-1 as well as interleukin-1β and tumor necrosis factor-α in 13 healthy volunteers and 28 alcoholics during weeks 1 and 4 following detoxification. Serum liver enzymes were obtained as markers of alcohol-related liver inflammation.

RESULTS

Compared to healthy volunteers, MCP-1 levels were significantly higher in alcoholics both on day 4 and day 25 (p < 0.0001). Using multiple regression analysis, we found that MCP-1 concentrations were positively associated with the liver enzymes gamma glutamyltransferase (GGT; p = 0.03) and aspartate aminotransferase/glutamic oxaloacetic transaminase (AST/GOT; p = 0.004).

CONCLUSIONS

These preliminary findings are consistent with the hypothesis that neuroinflammation as indexed by CSF MCP-1 is associated with alcohol-induced liver inflammation, as defined by peripheral concentrations of GGT and AST/GOT.

ISG54 and ISG56 are induced by TLR3 signaling in U373MG human astrocytoma cells: possible involvement in CXCL10 expression

Toll-like receptor (TLR) 3 is a pattern recognition receptor that recognizes double-stranded RNA (dsRNA). TLR3 signaling in astrocytes leads to the expression of interferon-β (IFN-β), and IFN-β regulates immune and inflammatory reactions by inducing IFN-stimulated genes (ISGs). We demonstrated in the present study that polyinosinic-polycytidylic acid (poly IC), an authentic dsRNA, up-regulated the expression of ISG54 and ISG56 in U373MG human astrocytoma cells. This reaction was confirmed to be mediated via the TLR3/IFN-β pathway. We also found that ISG56 positively regulates the expression of ISG54, retinoic acid-inducible gene-I (RIG-I) and melanoma differentiation-associated gene 5 (MDA5). In addition, positive feedback loops were found between ISG54 and ISG56, and also between ISG54 and RIG-I. RNA interference experiments revealed that all of ISG54, ISG56, RIG-I and MDA5 were involved in the poly IC-induced expression of a chemokine CXCL10. These results suggest that ISG54 and ISG56 are involved in the induction of CXCL10 in TLR3/IFN-β signaling at least partly by co-operating with RIG-I and MDA5. ISG54 and ISG56 may contribute to immune and inflammatory reactions elicited by the TLR3/IFN-β signaling pathway in astrocytes, and may play an important role both in antiviral immunity and in neuroinflammatory diseases.

Body fluid cytokine levels in mild cognitive impairment and Alzheimer's disease: a comparative overview

This article gives a comprehensive overview of cytokine and other inflammation associated protein levels in plasma, serum and cerebrospinal fluid (CSF) of patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI). We reviewed 118 research articles published between 1989 and 2013 to compare the reported levels of 66 cytokines and other proteins related to regulation and signaling in inflammation in the blood or CSF obtained from MCI and AD patients. Several cytokines are evidently regulated in (neuro-) inflammatory processes associated with neurodegenerative disorders. Others do not display changes in the blood or CSF during disease progression. However, many reports on cytokine levels in MCI or AD are controversial or inconclusive, particularly those which provide data on frequently investigated cytokines like tumor necrosis factor alpha (TNF-α) or interleukin-6 (IL-6). The levels of several cytokines are possible indicators of neuroinflammation in AD. Some of them might increase steadily during disease progression or temporarily at the time of MCI to AD conversion. Furthermore, elevated body fluid cytokine levels may correlate with an increased risk of conversion from MCI to AD. Yet, research results are conflicting. To overcome interindividual variances and to obtain a more definite description of cytokine regulation and function in neurodegeneration, a high degree of methodical standardization and patients collective characterization, together with longitudinal sampling over years is essential.

Chemokines and chemokine receptors in mood disorders, schizophrenia, and cognitive impairment: a systematic review of biomarker studies

The search for immune biomarkers in psychiatric disorders has primarily focused on pro-inflammatory cytokines. Other immune proteins including chemokines have been relatively neglected in such studies. Recent evidence has implicated chemokines in many neurobiological processes potentially relevant to psychiatric disorders, beyond their classical chemotactic functions. These may include neuromodulator effects, neurotransmitter-like effects, and direct/indirect regulation of neurogenesis. This systematic review presents the existing early evidence which supports an association of many chemokines with the psychiatric disorders: depression, bipolar disorder, schizophrenia, mild cognitive impairment and Alzheimer's disease. The non-specific association of chemokines including CXCL8 (IL-8), CCL2 (MCP-1), CCL3 (MIP-1α) and CCL5 (RANTES) with these disorders across diagnostic categories implies a generalised involvement of many chemokine systemic with psychiatric disease. Additional chemokines with great mechanistic relevance including CXCL12 (SDF-1) and CX3CL1 (fractalkine) have been rarely reported in the existing human literature and should be included in future clinical studies. The potential utility of these proteins as pathologically relevant biomarkers or therapeutic targets should be considered by future clinical and translational research.

Innate immune system and inflammation in Alzheimer's disease: from pathogenesis to treatment

Immune activation and inflammation, likely triggered by amyloid-beta (Aβ) deposition, play a remarkable role in the pathogenesis of Alzheimer's disease (AD), which is the most frequent cause of dementia in the elderly. The principal cellular elements of the brain innate immune system likely to be involved in such processes are microglia. In an attempt to search for new disease-modifying drugs, the immune system has been addressed, with the aim of removing deposition of Aβ or tau by developing vaccines and humanized monoclonal antibodies. The aim of this review is to summarize the current evidence regarding the role played by microglia and inflammatory molecules in the pathogenesis of AD. In addition, we will discuss the main active and passive immunotherapeutic approaches.

Interleukin-8 and interleukin-10, brain volume and microstructure, and the influence of calorie restriction in old rhesus macaques

Higher systemic levels of the proinflammatory cytokine interleukin-6 (IL-6) were found to be associated with lower gray matter volume and tissue density in old rhesus macaques. This association between IL-6, and these brain indices were attenuated by long-term 30 % calorie restriction (CR). To extend these findings, the current analysis determined if a CR diet in 27 aged rhesus monkeys compared to 17 normally fed controls reduced circulating levels of another proinflammatory cytokine, interleukin-8 (IL-8), and raised levels of anti-inflammatory interleukin-10 (IL-10). Further, these cytokines were regressed onto imaged brain volume and microstructure using voxel-wise regression analyses. CR significantly lowered IL-8 and raised IL-10 levels. Across the two dietary conditions, higher IL-8 predicted smaller gray matter volumes in bilateral hippocampus. Higher IL-10 was associated with more white matter volume in visual areas and tracts. Consuming a CR diet reduced the association between systemic IL-8 and hippocampal volumes. Conversely, CR strengthened associations between IL-10 and microstructural tissue density in the prefrontal cortex and other areas, particularly in a region of dorsal prefrontal cortex, which concurred with our prior findings for IL-6. Consumption of a CR diet lowered proinflammatory and increased anti-inflammatory cytokine concentrations, which lessened the statistical association between systemic inflammation and the age-related alterations in important brain regions, including the hippocampus.

Preconditioning of microglia by α-synuclein strongly affects the response induced by toll-like receptor (TLR) stimulation

In recent years, it has become accepted that α-synuclein (αSyn) has a key role in the microglia-mediated neuroinflammation, which accompanies the development of Parkinson’s disease and other related disorders, such as Dementia with Lewy Bodies and Alzheimer’s disease. Nevertheless, the cellular and molecular mechanisms underlying its pathological actions, especially in the sporadic forms of the diseases, are not completely understood. Intriguingly, several epidemiological and animal model studies have revealed a link between certain microbial infections and the onset or progression of sporadic forms of these neurodegenerative disorders. In this work, we have characterized the effect of toll-like receptor (TLR) stimulation on primary murine microglial cultures and analysed the impact of priming cells with extracellular wild-type (Wt) αSyn on the subsequent TLR stimulation of cells with a set of TLR ligands. By assaying key interleukins and chemokines we report that specific stimuli, in particular Pam3Csk4 (Pam3) and single-stranded RNA40 (ssRNA), can differentially affect the TLR2/1- and TLR7-mediated responses of microglia when pre-conditioned with αSyn by augmenting IL-6, MCP-1/CCL2 or IP-10/CXCL10 secretion levels. Furthermore, we report a skewing of αSyn-primed microglia stimulated with ssRNA (TLR7) or Pam3 (TLR2/1) towards intermediate but at the same time differential, M1/M2 phenotypes. Finally, we show that the levels and intracellular location of activated caspase-3 protein change significantly in αSyn-primed microglia after stimulation with these particular TLR agonists. Overall, we report a remarkable impact of non-aggregated αSyn pre-sensitization of microglia on TLR-mediated immunity, a phenomenon that could contribute to triggering the onset of sporadic α-synuclein-related neuropathologies.

Preoperative cerebrospinal fluid cytokine levels and the risk of postoperative delirium in elderly hip fracture patients

Background

Aging and neurodegenerative disease predispose to delirium and are both associated with increased activity of the innate immune system resulting in an imbalance between pro- and anti-inflammatory mediators in the brain. We examined whether hip fracture patients who develop postoperative delirium have altered levels of inflammatory mediators in cerebrospinal fluid (CSF) prior to surgery.

Methods

Patients were 75 years and older and admitted for surgical repair of an acute hip fracture. CSF samples were collected preoperatively. In an exploratory study, we measured 42 cytokines and chemokines by multiplex analysis. We compared CSF levels between patients with and without postoperative delirium and examined the association between CSF cytokine levels and delirium severity. Delirium was diagnosed with the Confusion Assessment Method; severity of delirium was measured with the Delirium Rating Scale Revised-98. Mann–Whitney U tests or Student t-tests were used for between-group comparisons and the Spearman correlation coefficient was used for correlation analyses.

Results

Sixty-one patients were included, of whom 23 patients (37.7%) developed postsurgical delirium. Concentrations of Fms-like tyrosine kinase-3 (P=0.021), Interleukin-1 receptor antagonist (P=0.032) and Interleukin-6 (P=0.005) were significantly lower in patients who developed delirium postoperatively.

Conclusions

Our findings fit the hypothesis that delirium after surgery results from a dysfunctional neuroinflammatory response: stressing the role of reduced levels of anti-inflammatory mediators in this process.

Trial registration

The Effect of Taurine on Morbidity and Mortality in the Elderly Hip Fracture Patient.

Registration number: NCT00497978. Local ethical protocol number: NL16222.094.07.

Impact of peripheral levels of chemokines, BDNF and oxidative markers on cognition in individuals with schizophrenia

OBJECTIVE

To investigate possible differences in peripheral levels of chemokines, BDNF and oxidative markers between patients with Schizophrenia (SZ) and matched healthy controls, and investigate the correlation of these biomarkers with cognitive performance.

METHODS

Thirty individuals with SZ and 27 healthy controls were included and the following plasmatic biomarkers' levels were determined according to manufacturers' instructions: BDNF, TBARS, protein carbonyl content (PCC) and the chemokines CXCL-10/IP-10, CXCL-8/IL-8, CCL-11, CCL-24/Eotaxin-2, CCL-2/MCP-1, CCL-3/MIP-1. Selected neuropsychological tasks were administered to assess verbal learning (Hopkins Verbal Learning Test), verbal fluency (FAS test), working memory (Visual Working Memory Task, Keep Track Task, Letter Memory Task), set shifting (Plus-minus task, Number-letter task), inhibition (Computerized Stroop Task, Semantic Generation Task) and complex executive function tasks (Tower of London and the shortened version of the WCST-64).

RESULTS

Compared with the healthy control group, individuals with SZ presented significantly higher levels of BDNF and the chemokine CCL-11, and lower levels of TBARS and the chemokine CXCL-10/IP-10. When we examined only the SZ group, BDNF levels were positively correlated with semantic generation tasks. Working memory ability was negatively correlated with PCC. Regarding chemokines, CCL-11 was negatively correlated to performance in working memory test, and positively correlated with cognitive flexibility task. CXCL-8/IL-8 was positively correlated with verbal fluency. CCL-24/Eotaxin-2 was positively correlated with semantic generation ability and letter memory task.

CONCLUSIONS

Our results indicate that cognitive performance in SZ is associated with mediators of neuroplasticity that can be measured peripherally.

A deficiency in CCR2+ monocytes: the hidden side of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by intracellular neurofibrillary tangle formation and extracellular amyloid-β (Aβ) deposition. To date, microglia seem to act as double-edged swords, being either beneficial (e.g. clearance of Aβ) or detrimental (e.g. secretion of neurotoxic factors) in AD. Following a rather intense debate on the question, a consensus has emerged that microglia can renew themselves via proliferation of already differentiated microglia as well as via the de novo recruitment of monocytes of mouse models of AD. However, recent advances suggest distinct function for resident and bone marrow-derived microglia (BMDM), and have emphasized the neuroprotective functions of BMDM. BMDM is the only subset of cells that restrict cerebral amyloidosis in the AD brain, which has been recently attributed to CCR2(+) monocytes. Moreover, an impaired recruitment of CCR2(+) monocytes has been reported in AD patients, as seen from the CCR2(+) monocytopenia found in the bloodstream and BM. The present review summarizes the current knowledge on the roles and dysfunctions of CCR2(+) monocytes in AD and their potential as key therapeutic targets.

The role of the innate immune system in Alzheimer's disease and frontotemporal lobar degeneration: an eye on microglia

In the last few years, genetic and biomolecular mechanisms at the basis of Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD) have been unraveled. A key role is played by microglia, which represent the immune effector cells in the central nervous system (CNS). They are extremely sensitive to the environmental changes in the brain and are activated in response to several pathologic events within the CNS, including altered neuronal function, infection, injury, and inflammation. While short-term microglial activity has generally a neuroprotective role, chronic activation has been implicated in the pathogenesis of neurodegenerative disorders, including AD and FTLD. In this framework, the purpose of this review is to give an overview of clinical features, genetics, and novel discoveries on biomolecular pathogenic mechanisms at the basis of these two neurodegenerative diseases and to outline current evidence regarding the role played by activated microglia in their pathogenesis.

Expression of CXCR3 and its ligands CXCL9, -10 and -11 in paediatric opsoclonus-myoclonus syndrome

Opsoclonus-myoclonus syndrome (OMS) is a neuroinflammatory disorder associated with remote cancer. To understand more clearly the role of inflammatory mediators, the concentration of CXCR3 ligands CXCL10, CXCL9 and CXCL11 was measured in 245 children with OMS and 81 paediatric controls using enzyme-linked immunosorbent assay (ELISA), and CXCR3 expression on CD4(+) T cells was measured by flow cytometry. Mean cerebrospinal fluid (CSF) CXCL10 was 2·7-fold higher in untreated OMS than controls. Intrathecal production was demonstrated by significantly different CXCL10 CSF : serum ratios. The dichotomized 'high' CSF CXCL10 group had higher CSF leucocyte count (P = 0·0007) and B cell activating factor (BAFF) and CXCL13 concentrations (P < 0·0001). CSF CXCL10 did not correlate with clinical severity or relapse using grouped data, although it did in some patients. Among seven types of immunotherapy, including rituximab or chemotherapy, only adrenocorticotrophic hormone (ACTH) monotherapy showed reduced CSF CXCL10, but prospective longitudinal studies of ACTH combination therapies indicated no reduction in CXCL10 despite clinical improvement (P < 0·0001). CXCL10 concentrations were 11-fold higher in CSF and twofold higher in serum by multiplexed fluorescent bead-based immunoassay than enzyme-linked immunosorbent assay, but the two correlated (r = 0·7 and 0·83). In serum, no group differences for CXCL9 or CXCL11 were found. CXCR3 expression on CD4(+) T cells was fivefold higher in those from CSF than blood, but was not increased in OMS or altered by conventional immunotherapy. These data suggest alternative roles for CXCL10 in OMS. Over-expression of CXCL10 was not reduced by clinical immunotherapies as a whole, indicating the need for better therapeutic approaches.

MDA5 and ISG56 mediate CXCL10 expression induced by toll-like receptor 4 activation in U373MG human astrocytoma cells

Toll-like receptor (TLR) 4 is a pattern recognition receptor, and recognizes not only bacterial lipopolysaccharide (LPS) but also endogenous danger-associated molecular patterns released from dying or injured cells. It has been reported that TLR4 signaling in astrocytes plays an important role in various neurological diseases. However, details of TLR4 signaling in astrocytes are not fully elucidated. In the present study, we demonstrated that TLR4 signaling, induced by LPS, increases the expression of melanoma differentiation-associated gene 5 (MDA5) and interferon (IFN)-stimulated gene 56 (ISG56) in U373MG human astrocytoma cells. We also found that nuclear factor-κB, p38 mitogen-activated protein kinase and IFN-β are involved in the expression of MDA5 and ISG56 induced by LPS. RNA interference experiments revealed that MDA5 and ISG56 positively regulate the LPS-induced expression of a chemokine CXCL10, but not CCL2. In addition, it was suggested that MDA5 and ISG56 constitute a positive feedback loop. These results suggest that MDA5 and ISG56 may contribute not only to physiological inflammatory reactions but also to the pathogenesis of various neurological diseases elicited by TLR4 in astrocytes, at least in part, by regulating the expression of CXCL10.

Cerebrospinal fluid biomarkers for pathological processes in Alzheimer's disease

PURPOSE OF REVIEW

To review the rationale behind and the use of cerebrospinal fluid (CSF) biomarkers in Alzheimer's disease (AD). Established as well as new candidate biomarkers will be covered.

RECENT FINDINGS

AD is a complex disorder and the AD brain is characterized by multiple pathological processes, in addition to well-described plaque and tangle diseases. Recent studies have tried to address this by evaluating biomarkers related to features such as neuroinflammation, oxidative stress, microglial activation and synaptic degeneration, with some positive results.

SUMMARY

The CSF biomarkers total tau, phosphorylated-tau and the 42 amino acid isoform of amyloid beta reflect core elements of AD, that is, axonal degeneration, tangle disease and senile plaques, have been thoroughly tested and provide high diagnostic accuracy in the discrimination of patients with AD as compared with cognitively normal controls. They are also highly predictive of AD with dementia in patients with mild cognitive impairment, and have been included in new diagnostic criteria. New biomarkers may add to their diagnostic performance. Other potential fields of use include the monitoring of disease progression or pharmacodynamic drug effects. A common denominator for the candidate biomarkers is the need for validation in further studies to clarify their potential.

Pharmacologic inhibition of CXCL10 in combination with anti-malarial therapy eliminates mortality associated with murine model of cerebral malaria

Despite appropriate anti-malarial treatment, cerebral malaria (CM)-associated mortalities remain as high as 30%. Thus, adjunctive therapies are urgently needed to prevent or reduce such mortalities. Overproduction of CXCL10 in a subset of CM patients has been shown to be tightly associated with fatal human CM. Mice with deleted CXCL10 gene are partially protected against experimental cerebral malaria (ECM) mortality indicating the importance of CXCL10 in the pathogenesis of CM. However, the direct effect of increased CXCL10 production on brain cells is unknown. We assessed apoptotic effects of CXCL10 on human brain microvascular endothelial cells (HBVECs) and neuroglia cells in vitro. We tested the hypothesis that reducing overexpression of CXCL10 with a synthetic drug during CM pathogenesis will increase survival and reduce mortality. We utilized atorvastatin, a widely used synthetic blood cholesterol-lowering drug that specifically targets and reduces plasma CXCL10 levels in humans, to determine the effects of atorvastatin and artemether combination therapy on murine ECM outcome. We assessed effects of atorvastatin treatment on immune determinants of severity, survival, and parasitemia in ECM mice receiving a combination therapy from onset of ECM (day 6 through 9 post-infection) and compared results with controls. The results indicate that CXCL10 induces apoptosis in HBVECs and neuroglia cells in a dose-dependent manner suggesting that increased levels of CXCL10 in CM patients may play a role in vasculopathy, neuropathogenesis, and brain injury during CM pathogenesis. Treatment of ECM in mice with atorvastatin significantly reduced systemic and brain inflammation by reducing the levels of the anti-angiogenic and apoptotic factor (CXCL10) and increasing angiogenic factor (VEGF) production. Treatment with a combination of atorvastatin and artemether improved survival (100%) when compared with artemether monotherapy (70%), p<0.05. Thus, adjunctively reducing CXCL10 levels and inflammation by atorvastatin treatment during anti-malarial therapy may represent a novel approach to treating CM patients.

Inflammatory Markers and Their Association with Post Stroke Cognitive Decline

Background

Population-based studies have demonstrated the association of inflammation and cognitive impairment. However, few studies to date have examined this association in ischemic stroke patients.

Aims

The study aims to determine the association between inflammatory markers and cognitive impairment.

Methods

Ischemic stroke patients with baseline neuropsychological assessments at three-months poststroke were followed up with annual neuropsychological assessments for up to five-years. Inflammatory markers (C-reactive protein, interleukin 1β, interleukin 6, interleukin 8, interleukin 10, interleukin 12, and tumor necrosis factor-α) were assayed, and logistic regression analyses were performed to determine associations between inflammatory markers and both baseline cognitive status and subsequent cognitive decline.

Results

There were 243 ischemic stroke patients in the study. In multivariable ordinal logistic regression analysis, age, education, ethnicity, stroke subtype, and interleukin 8 (OR 1·23 CI 1·05–1·44) levels were independently associated with baseline cognitive status. In multivariable logistic regression analyses, age, gender, recurrent strokes, and interleukin 12 (OR 25·02 CI 3·73 to 168·03) were independent predictors of subsequent cognitive decline.

Conclusions

Following ischemic stroke, higher serum interleukin 8 is independently associated with baseline cognitive impairment while higher serum interleukin 12 is associated with subsequent cognitive decline.

Histone deacetylases enzyme, copper, and IL-8 levels in patients with Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive loss of cognitive abilities. Epigenetic modification, oxidative stress, and inflammation play an important role in the pathogenesis of the disease. We aimed to detect noninvasive peripheral biomarkers with a high degree of sensitivity and specificity in diagnosis and progression of AD.

METHODS

A total of 25 elderly patients with AD and 25 healthy control participants were selected and subjected to cognitive assessment and laboratory measures including histone deacetylases (HDACs), copper, and interleukin 8 (IL-8) levels.

RESULTS

The levels of HDACs, copper, and IL-8 were significantly higher in patients with AD (P < .001) and had a significant negative effect on all cognitive assessment tests. Receiver-operating curve (ROC) analysis revealed that HDACs and copper levels had higher sensitivity and specificity.

CONCLUSIONS

Plasma levels of HDACs and copper may be used as peripheral biomarkers in diagnosis of AD, while IL-8 level could be a useful biomarker in following AD progression.

Cortical beta amyloid protein triggers an immune response, but no synaptic changes in the APPswe/PS1dE9 Alzheimer's disease mouse model

Using microarray technology we studied the genome-wide gene expression profiles in the frontal cortex of APPswe/PS1dE9 mice and age and sex-matched littermates at the age of 2, 3, 6, 9, 12, and 15-18 months to investigate transcriptional changes that are associated with beta amyloid protein (Aβ) plaque formation and buildup. We observed the occurrence of an immune response with glial activation, but no changes in genes involved in synaptic transmission or plasticity. Comparison of the mouse gene expression data set with a human data set representing the course of Alzheimer's disease revealed a strikingly limited overlap between gene expression in the APPswe/PS1dE9 and human Alzheimer's disease prefrontal cortex. Only plexin domain containing 2, complement component 4b, and solute carrier family 14 (urea transporter) member 1 were significantly upregulated in the mouse and human brain which might suggest a function in Aβ pathology for these 3 genes. In both data sets we detected clusters of upregulated genes involved in immune-related processes. We conclude that the APPswe/PS1dE9 mouse can be a good model to study the immune response associated with cortical Aβ plaques.