Intrathecal levels of IL-6, IL-11 and LIF in Alzheimer's disease and frontotemporal lobar degeneration

An optimized procedure for preparation of conditioned medium from Wharton's jelly mesenchymal stromal cells isolated from umbilical cord

Cell-free therapy based on conditioned medium derived from mesenchymal stromal cells (MSCs) has gained attention in the field of protective and regenerative medicine. However, the exact composition and properties of MSC-derived conditioned media can vary greatly depending on multiple parameters, which hamper standardization. In this study, we have optimized a procedure for preparation of conditioned medium starting from efficient isolation, propagation and characterization of MSCs from human umbilical cord, using a culture medium supplemented with human platelet lysate as an alternative source to fetal bovine serum. Our procedure successfully maximizes the yield of viable MSCs that maintain canonical key features. Importantly, under these conditions, the compositional profile and biological effects elicited by the conditioned medium preparations derived from these MSC populations do not depend on donor individuality. Moreover, approximately 120 L of conditioned medium could be obtained from a single umbilical cord, which provides a suitable framework to produce industrial amounts of toxic-free conditioned medium with predictable composition.

Association of pro-inflammatory diet with increased risk of all-cause dementia and Alzheimer's dementia: a prospective study of 166,377 UK Biobank participants

BACKGROUND

Increasing evidence suggests an association between pro-inflammatory diets and cognitive function. However, only a few studies based on small sample sizes have explored the association between pro-inflammatory diets and dementia using the dietary inflammatory index (DII). Additionally, the relationship between DII and different subtypes of dementia, such as Alzheimer's dementia and vascular dementia, remains largely unexplored. Given the changes in brain structure already observed in patients with dementia, we also investigated the association between DII and magnetic resonance imaging (MRI) measures of brain structure to provide some hints to elucidate the potential mechanisms between pro-inflammatory diet and cognitive decline.

METHODS

A total of 166,377 UK Biobank participants without dementia at baseline were analyzed. DII calculations were based on the information collected by the 24-h recall questionnaire. Brain structural anatomy and tissue-specific volumes were measured using brain MRI. Cox proportional hazards models, competing risk models, and restricted cubic spline were applied to assess the longitudinal associations. The generalized linear model was used to assess the association between DII and MRI measurements.

RESULTS

During a median follow-up time of 9.46 years, a total of 1372 participants developed dementia. The incidence of all-cause dementia increased by 4.6% for each additional unit of DII [hazard ratio (HR): 1.046]. Besides, DII displayed a "J-shaped" non-linear association with Alzheimer's dementia (P_nonlinear = 0.003). When DII was above 1.30, an increase in DII was significantly associated with an increased risk of Alzheimer's dementia (HR: 1.391, 95%CI: 1.085-1.784, P = 0.009). For brain MRI, the total volume of white matter hyperintensities increased with an increase in DII, whereas the volume of gray matter in the hippocampus decreased.

CONCLUSIONS

In this cohort study, higher DII was associated with a higher risk of all-cause dementia and Alzheimer's dementia. However, our findings suggested that the association with DII and vascular and frontotemporal dementia was not significant.

Elevated GRO-α and IL-18 in serum and brain implicate the NLRP3 inflammasome in frontotemporal dementia

Neuroinflammation is a hallmark of frontotemporal dementia (FTD), a heterogeneous group of proteinopathies characterized by the progressive degeneration of the frontal and temporal lobes. It is marked by microglial activation and subsequent cytokine release. Although cytokine levels in FTD brain and CSF have been examined, the number of cytokines measured in each study is limited and knowledge on cytokine concentrations in FTD serum is scarce. Here, we assessed 48 cytokines in FTD serum and brain. The aim was to determine common cytokine dysregulation pathways in serum and brain in FTD. Blood samples and brain tissue samples from the superior frontal cortex (SFC) were collected from individuals diagnosed with behavioral variant FTD (bvFTD) and healthy controls, and 48 cytokines were measured using a multiplex immunological assay. The data were evaluated by principal component factor analysis to determine the contribution from different components of the variance in the cohort. Levels of a number of cytokines were altered in serum and SFC in bvFTD compared to controls, with increases in GRO-α and IL-18 in both serum and SFC. These changes could be associated with NLRP3 inflammasome activation or the NFκB pathway, which activates NLRP3. The results suggest the possible importance of the NLRP3 inflammasome in FTD. An improved understanding of the role of inflammasomes in FTD could provide valuable insights into the pathogenesis, diagnosis and treatment of FTD.

CSF Biomarkers in the Early Diagnosis of Mild Cognitive Impairment and Alzheimer's Disease

Alzheimer's disease (AD) is a rapidly growing disease that affects millions of people worldwide, therefore there is an urgent need for its early diagnosis and treatment. A huge amount of research studies are performed on possible accurate and reliable diagnostic biomarkers of AD. Due to its direct contact with extracellular space of the brain, cerebrospinal fluid (CSF) is the most useful biological fluid reflecting molecular events in the brain. Proteins and molecules that reflect the pathogenesis of the disease, e.g., neurodegeneration, accumulation of Abeta, hyperphosphorylation of tau protein and apoptosis may be used as biomarkers. The aim of the current manuscript is to present the most commonly used CSF biomarkers for AD as well as novel biomarkers. Three CSF biomarkers, namely total tau, phospho-tau and Abeta42, are believed to have the highest diagnostic accuracy for early AD diagnosis and the ability to predict AD development in mild cognitive impairment (MCI) patients. Moreover, other biomarkers such as soluble amyloid precursor protein (APP), apoptotic proteins, secretases and inflammatory and oxidation markers are believed to have increased future prospects.

Butyl benzyl phthalate as a key component of phthalate ester in relation to cognitive impairment in NHANES elderly individuals and experimental mice

Phthalates are a group of neurotoxicants with cognitive-disrupting potentials. Given the structural diversity of phthalates, the corresponding neurotoxicity is dramatically altered. To identify the potential contributions of different phthalates on the process of cognitive impairment, data of 836 elders from the NHANES 2011-2014 cycles were used. Survey-weighted logistic regression and principal component analysis-weighted quantile sum regression (PCA-WQSR) models were applied to estimate the independent and combined associations of 11 urinary phthalate metabolites with cognitive deficit (assessed by 4 tests: Immediate Recall (IR), Delayed Recall (DR), Animal Fluency (AF), and Digit Symbol Substitution Test (DSST)) and to identify the potential phthalate with high weight. Laboratory mice were further used to examine the effect of phthalates on cognitive function and to explore the potential mechanisms. In logistic regression models, MBzP was the only metabolite positively correlated with four tests, with ORs of 2.53 (quartile 3 (Q3)), 2.26 (Q3), 2.89 (Q4) and 2.45 (Q2), 2.82 (Q4) for IR, DR, AF, and DSST respectively. In PCA-WQSR co-exposure models, low-molecular-weight (LMW) phthalates were the only PC positively linked to DSST deficit (OR: 1.93), which was further validated in WQSR analysis (WQS OR7-phthalates: 1.56 and WQS OR8-phthalates: 1.55); consistent with the results of logistic regression, MBzP was the dominant phthalate. In mice, butyl benzyl phthalate (BBP), the parent phthalate of MBzP, dose-dependently reduced cognitive function and disrupted hippocampal neurons. Additionally, the hippocampal transcriptome analysis identified 431 differential expression genes, among which most were involved in inhibiting the neuroactive ligand-receptor interaction pathway and activating the cytokine-cytokine receptor interaction pathway. Our study indicates the critical role of BBP in the association of phthalates and cognitive deficits among elderly individuals, which might be speculated that BBP could disrupt hippocampal neurons, activate neuroinflammation, and inhibit neuroactive receptors. Our findings provide new insight into the cognitive-disrupting potential of BBP.

Peripheral inflammation in behavioural variant frontotemporal dementia: associations with central degeneration and clinical measures

BACKGROUND

Neuroinflammation plays a significant role in the progression of frontotemporal dementia (FTD). However, the association between peripheral inflammatory factors and brain neurodegeneration is poorly understood. We aimed to examine changes in peripheral inflammatory markers in patients with behavioural variant FTD (bvFTD) and explore the potential association between peripheral inflammation and brain structure, metabolism, and clinical parameters.

METHODS

Thirty-nine bvFTD patients and 40 healthy controls were enrolled and underwent assessment of plasma inflammatory factors, positron emission tomography/magnetic resonance imaging, and neuropsychological assessments. Group differences were tested using Student's t test, Mann‒Whitney U test, or ANOVA. Partial correlation analysis and multivariable regression analysis were implemented using age and sex as covariates to explore the association between peripheral inflammatory markers, neuroimaging, and clinical measures. The false discovery rate was used to correct for the multiple correlation test.

RESULTS

Plasma levels of six factors, including interleukin (IL)-2, IL-12p70, IL-17A, tumour necrosis superfamily member 13B (TNFSF/BAFF), TNFSF12 (TWEAK), and TNFRSF8 (sCD30), were increased in the bvFTD group. Five factors were significantly associated with central degeneration, including IL-2, IL-12p70, IL-17A, sCD30/TNFRSF8, and tumour necrosis factor (TNF)-α; the association between inflammation and brain atrophy was mainly distributed in frontal-limbic-striatal brain regions, whereas the association with brain metabolism was mainly in the frontal-temporal-limbic-striatal regions. BAFF/TNFSF13B, IL-4, IL-6, IL-17A and TNF-α were found to correlate with clinical measures.

CONCLUSION

Peripheral inflammation disturbance in patients with bvFTD participates in disease-specific pathophysiological mechanisms, which could be a promising target for diagnosis, treatment, and monitoring therapeutic efficacy.

Cytokine storm and neuropathological alterations in patients with neurological manifestations of COVID-19

The COVID-19 pandemic is caused by the severe acute respiratory syndrome coronavirus (SARS-CoV-2), a respiratory pathogen with neuroinvasive potential. Neurological COVID-19 manifestations include loss of smell and taste, headache, dizziness, stroke, and potentially fatal encephalitis. Several studies found elevated proinflammatory cytokines such as TNF-α, IFN-γ, IL-6 IL-8, IL-10 IL-16, IL-17A, and IL-18 in severely and critically ill COVID-19 patients, which may persist even after apparent recovery from infection. Biomarker studies on CSF and plasma and serum from COVID-19 patients have also shown a high level of IL-6, intrathecal IgG, neurofilament light chain (NFL), glial fibrillary acidic protein (GFAP), and tau protein. Emerging evidence on the matter has established the concept of COVID-19 associated neuroinflammation, in the context of COVID-19 associated cytokine storm. While the short-term implications of this condition are extensively documented, its long-term implications are yet to be understood. The association of the aforementioned cytokines with the pathogenesis of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, Huntington disease, and amyotrophic lateral sclerosis, may increase COVID-19 patients' risk to develop neurodegenerative diseases. Analysis of proinflammatory cytokines and CSF biomarkers in patients with COVID-19 can contribute to the early detection of the disease's exacerbation, monitoring the neurological implications of the disease and devising risk scales, and identifying treatment targets.

Elevated CSF and plasma complement proteins in genetic frontotemporal dementia: results from the GENFI study

BACKGROUND

Neuroinflammation is emerging as an important pathological process in frontotemporal dementia (FTD), but biomarkers are lacking. We aimed to determine the value of complement proteins, which are key components of innate immunity, as biomarkers in cerebrospinal fluid (CSF) and plasma of presymptomatic and symptomatic genetic FTD mutation carriers.

METHODS

We measured the complement proteins C1q and C3b in CSF by ELISAs in 224 presymptomatic and symptomatic GRN, C9orf72 or MAPT mutation carriers and non-carriers participating in the Genetic Frontotemporal Dementia Initiative (GENFI), a multicentre cohort study. Next, we used multiplex immunoassays to measure a panel of 14 complement proteins in plasma of 431 GENFI participants. We correlated complement protein levels with corresponding clinical and neuroimaging data, neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP).

RESULTS

CSF C1q and C3b, as well as plasma C2 and C3, were elevated in symptomatic mutation carriers compared to presymptomatic carriers and non-carriers. In genetic subgroup analyses, these differences remained statistically significant for C9orf72 mutation carriers. In presymptomatic carriers, several complement proteins correlated negatively with grey matter volume of FTD-related regions and positively with NfL and GFAP. In symptomatic carriers, correlations were additionally observed with disease duration and with Mini Mental State Examination and Clinical Dementia Rating scale® plus NACC Frontotemporal lobar degeneration sum of boxes scores.

CONCLUSIONS

Elevated levels of CSF C1q and C3b, as well as plasma C2 and C3, demonstrate the presence of complement activation in the symptomatic stage of genetic FTD. Intriguingly, correlations with several disease measures in presymptomatic carriers suggest that complement protein levels might increase before symptom onset. Although the overlap between groups precludes their use as diagnostic markers, further research is needed to determine their potential to monitor dysregulation of the complement system in FTD.

Louis EK, Przybelski SA, Morgenthaler TI, Machulda MM, Boeve BF, Petersen RC, Jack CR, Graff-Radford J, Vemuri P, Mielke MM. Sleepiness in Cognitively Unimpaired Older Adults Is Associated With CSF Biomarkers of Inflammation and Axonal Integrity

Introduction

Sleepiness has been associated with cognitive decline and dementia in the elderly. Older adults with excessive daytime sleepiness appear to be more vulnerable to longitudinal amyloid PET accumulation before the onset of the dementia. However, it remains unclear whether sleepiness is similarly associated with other biomarkers of Alzheimer's disease (AD), axonal integrity, and inflammation, which may also contribute to neurodegeneration and cognitive decline.

Methods

In this cross-sectional analysis, we identified 260 cognitively unimpaired adults (>60 years) from the Mayo Clinic Study of Aging, a population-based cohort from Olmsted County (MN), who underwent CSF quantification of AD biomarkers (Aβ42, p-tau, p-tau/Aβ42) in addition to at least one of the following biomarkers [neurofilament light chain (NfL) interleukin-6 (IL-6), IL-10, and tumor necrosis factor-α (TNF-α)]. We fit linear regression models to assess associations between sleepiness, as measured by the Epworth Sleepiness Scale (ESS), and CSF biomarkers, controlling for age, sex, APOε4 status, body mass index, hypertension, dyslipidemia, and prior diagnosis of obstructive sleep apnea.

Results

Higher ESS scores were associated with higher CSF IL-6 and NfL, but not with the other CSF biomarkers. For every ESS score point increase, there was a 0.009 ([95% CI 0.001-0.016], p = 0.033) increase in the log of IL-6 and 0.01 ([95% CI 0.002-0.018], p = 0.016) increase in the log of NfL. A sensitivity analysis showed an association between ESS scores and log of p-tau/Aβ42 only in participants with an abnormal ratio (>0.023), highly predictive of amyloid positivity. For every ESS score point increase, there was a 0.006 ([95% CI 0.001-0.012], p = 0.021) increase in the log of CSF p-tau/Aβ42.

Conclusion

Sleepiness was associated with greater CSF IL-6 and NfL levels, which could contribute to neurodegeneration or alternatively cause sleepiness. Higher NfL levels may result from sleep disruption and/or contribute to sleepiness via disturbed connectivity or damage to wake-promoting centers. Associations between sleepiness and p-tau/Aβ42 in participants with abnormal ratio suggest that amyloid positivity contributes to vulnerability to sleep disturbance, which may further amyloid accumulation in a feed-forward loop process. Prospective studies of these markers are needed to determine cause-effect relationships between these associations.

Decreased Netrin-1 in Mild Cognitive Impairment and Alzheimer’s Disease Patients

Background and Objective

Inflammatory mediators are closely associated with the pathogenesis of Alzheimer’s disease (AD) and mild cognitive impairment (MCI). Netrin-1 is an axon guidance protein and despite its capacity to function as a neuroimmune guidance signal, its role in AD or MCI is poorly understood. In addition, the association among netrin-1, cognitive impairment and serum inflammatory cytokines such as interleukin-17 (IL-17) and tumor necrosis (TNF-α) remains unclear. The aim of this study was to determine serum levels of IL-17, TNF-α and netrin-1in a cohort of AD and MCI patients, and to study the relationship between these cytokines and cognitive status, as well as to assess the possible relationships between netrin-1 levels and inflammatory molecules.

Methods

Serum concentrations of netrin-1, TNF-α and IL-17 were determined in 20 AD patients, 22 MCI patients and 22 healthy controls using an enzyme-linked immunosorbent assay (ELISA). In addition, neuropsychological evaluations and psychometric assessments were performed in all subjects.

Results

Serum netrin-1 levels were decreased in AD and MCI patients and were positively correlated with Mini Mental State Examination (MMSE) scores. In contrast, serum TNF-α and IL-17 levels were elevated in AD and MCI cohorts and negatively correlated with MMSE scores. Serum netrin-1 levels were inversely related with TNF-α and IL-17 levels in AD, but not MCI, patients.

Conclusion

Based on the findings reported here, netrin-1 may serve as a marker for the early recognition of dementia and predict cognitive impairment.

Neuroinflammation in Amyotrophic Lateral Sclerosis and Frontotemporal Dementia and the Interest of Induced Pluripotent Stem Cells to Study Immune Cells Interactions With Neurons

Inflammation is a shared hallmark between amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). For long, studies were conducted on tissues of post-mortem patients and neuroinflammation was thought to be only bystander result of the disease with the immune system reacting to dying neurons. In the last two decades, thanks to improving technologies, the identification of causal genes and the development of new tools and models, the involvement of inflammation has emerged as a potential driver of the diseases and evolved as a new area of intense research. In this review, we present the current knowledge about neuroinflammation in ALS, ALS-FTD, and FTD patients and animal models and we discuss reasons of failures linked to therapeutic trials with immunomodulator drugs. Then we present the induced pluripotent stem cell (iPSC) technology and its interest as a new tool to have a better immunopathological comprehension of both diseases in a human context. The iPSC technology giving the unique opportunity to study cells across differentiation and maturation times, brings the hope to shed light on the different mechanisms linking neurodegeneration and activation of the immune system. Protocols available to differentiate iPSC into different immune cell types are presented. Finally, we discuss the interest in studying monocultures of iPS-derived immune cells, co-cultures with neurons and 3D cultures with different cell types, as more integrated cellular approaches. The hope is that the future work with human iPS-derived cells helps not only to identify disease-specific defects in the different cell types but also to decipher the synergistic effects between neurons and immune cells. These new cellular tools could help to find new therapeutic approaches for all patients with ALS, ALS-FTD, and FTD.

Differential chemokine alteration in the variants of primary progressive aphasia-a role for neuroinflammation

BACKGROUND

The primary progressive aphasias (PPA) represent a group of usually sporadic neurodegenerative disorders with three main variants: the nonfluent or agrammatic variant (nfvPPA), the semantic variant (svPPA), and the logopenic variant (lvPPA). They are usually associated with a specific underlying pathology: nfvPPA with a primary tauopathy, svPPA with a TDP-43 proteinopathy, and lvPPA with underlying Alzheimer's disease (AD). Little is known about their cause or pathophysiology, but prior studies in both AD and svPPA have suggested a role for neuroinflammation. In this study, we set out to investigate the role of chemokines across the PPA spectrum, with a primary focus on central changes in cerebrospinal fluid (CSF) METHODS: Thirty-six participants with sporadic PPA (11 svPPA, 13 nfvPPA, and 12 lvPPA) as well as 19 healthy controls were recruited to the study and donated CSF and plasma samples. All patients with lvPPA had a tau/Aβ42 biomarker profile consistent with AD, whilst this was normal in the other PPA groups and controls. We assessed twenty chemokines in CSF and plasma using Proximity Extension Assay technology: CCL2 (MCP-1), CCL3 (MIP-1a), CCL4 (MIP-1β), CCL7 (MCP-3), CCL8 (MCP-2), CCL11 (eotaxin), CCL13 (MCP-4), CCL19, CCL20, CCL23, CCL25, CCL28, CX3CL1 (fractalkine), CXCL1, CXCL5, CXCL6, CXCL8 (IL-8), CXCL9, CXCL10, and CXCL11.

RESULTS

In CSF, CCL19 and CXCL6 were decreased in both svPPA and nfvPPA compared with controls whilst CXCL5 was decreased in the nfvPPA group with a borderline significant decrease in the svPPA group. In contrast, CCL2, CCL3 and CX3CL1 were increased in lvPPA compared with controls and nfvPPA (and greater than svPPA for CX3CL1). CXCL1 was also increased in lvPPA compared with nfvPPA but not the other groups. CX3CL1 was significantly correlated with CSF total tau concentrations in the controls and each of the PPA groups. Fewer significant differences were seen between groups in plasma, although in general, results were in the opposite direction to CSF, i.e. decreased in lvPPA compared with controls (CCL3 and CCL19), and increased in svPPA (CCL8) and nfvPPA (CCL13).

CONCLUSION

Differential alteration of chemokines across the PPA variants is seen in both CSF and plasma. Importantly, these results suggest a role for neuroinflammation in these poorly understood sporadic disorders, and therefore also a potential future therapeutic target.

Different Inflammatory Signatures in Alzheimer's Disease and Frontotemporal Dementia Cerebrospinal Fluid

Background:

Neuroinflammatory processes are common in neurodegenerative diseases such as Alzheimer’s disease (AD) and frontotemporal dementia (FTD), but current knowledge is limited as to whether cerebrospinal fluid (CSF) levels of neuroinflammatory proteins are altered in these diseases.

Objective:

To identify and characterize neuroinflammatory signatures in CSF from patients with AD, mild cognitive impairment (MCI), and FTD.

Methods:

We used proximity extension assay and ANOVA to measure and compare levels of 92 inflammatory proteins in CSF from 42 patients with AD, 29 with MCI due to AD (MCI/AD), 22 with stable MCI, 42 with FTD, and 49 control subjects, correcting for age, gender, collection unit, and multiple testing.

Results:

Levels of matrix metalloproteinase-10 (MMP-10) were increased in AD, MCI/AD, and FTD compared with controls (AD: fold change [FC] = 1.32, 95% confidence interval [CI] 1.14–1.53, q = 0.018; MCI/AD: FC = 1.53, 95% CI 1.20–1.94, q = 0.045; and FTD: FC = 1.42, 95% CI 1.10–1.83, q = 0.020). MMP-10 and eleven additional proteins were increased in MCI/AD, compared with MCI (q < 0.05). In FTD, 36 proteins were decreased, while none was decreased in AD or MCI/AD, compared with controls (q < 0.05).

Conclusion:

In this cross-sectional multi-center study, we found distinct patterns of CSF inflammatory marker levels in FTD and in both early and established AD, suggesting differing neuroinflammatory processes in the two disorders.

Systematic Review: Genetic, Neuroimaging, and Fluids Biomarkers for Frontotemporal Dementia Across Latin America Countries

Frontotemporal dementia (FTD) includes a group of clinically, genetically, and pathologically heterogeneous neurodegenerative disorders, affecting the fronto-insular-temporal regions of the brain. Clinically, FTD is characterized by progressive deficits in behavior, executive function, and language and its diagnosis relies mainly on the clinical expertise of the physician/consensus group and the use of neuropsychological tests and/or structural/functional neuroimaging, depending on local availability. The modest correlation between clinical findings and FTD neuropathology makes the diagnosis difficult using clinical criteria and often leads to underdiagnosis or misdiagnosis, primarily due to lack of recognition or awareness of FTD as a disease and symptom overlap with psychiatric disorders. Despite advances in understanding the underlying neuropathology of FTD, accurate and sensitive diagnosis for this disease is still lacking. One of the major challenges is to improve diagnosis in FTD patients as early as possible. In this context, biomarkers have emerged as useful methods to provide and/or complement clinical diagnosis for this complex syndrome, although more evidence is needed to incorporate most of them into clinical practice. However, most biomarker studies have been performed using North American or European populations, with little representation of the Latin American and the Caribbean (LAC) region. In the LAC region, there are additional challenges, particularly the lack of awareness and knowledge about FTD, even in specialists. Also, LAC genetic heritage and cultures are complex, and both likely influence clinical presentations and may modify baseline biomarker levels. Even more, due to diagnostic delay, the clinical presentation might be further complicated by both neurological and psychiatric comorbidity, such as vascular brain damage, substance abuse, mood disorders, among others. This systematic review provides a brief update and an overview of the current knowledge on genetic, neuroimaging, and fluid biomarkers for FTD in LAC countries. Our review highlights the need for extensive research on biomarkers in FTD in LAC to contribute to a more comprehensive understanding of the disease and its associated biomarkers. Dementia research is certainly reduced in the LAC region, highlighting an urgent need for harmonized, innovative, and cross-regional studies with a global perspective across multiple areas of dementia knowledge.

Seminal plasma promotes decidualization of endometrial stromal fibroblasts in vitro from women with and without inflammatory disorders in a manner dependent on interleukin-11 signaling

STUDY QUESTION

Do seminal plasma (SP) and its constituents affect the decidualization capacity and transcriptome of human primary endometrial stromal fibroblasts (eSFs)?

SUMMARY ANSWER

SP promotes decidualization of eSFs from women with and without inflammatory disorders (polycystic ovary syndrome (PCOS), endometriosis) in a manner that is not mediated through semen amyloids and that is associated with a potent transcriptional response, including the induction of interleukin (IL)-11, a cytokine important for SP-induced decidualization.

WHAT IS KNOWN ALREADY

Clinical studies have suggested that SP can promote implantation, and studies in vitro have demonstrated that SP can promote decidualization, a steroid hormone-driven program of eSF differentiation that is essential for embryo implantation and that is compromised in women with the inflammatory disorders PCOS and endometriosis.

STUDY DESIGN, SIZE, DURATION

This is a cross-sectional study involving samples treated with vehicle alone versus treatment with SP or SP constituents. SP was tested for the ability to promote decidualization in vitro in eSFs from women with or without PCOS or endometriosis (n = 9). The role of semen amyloids and fractionated SP in mediating this effect and in eliciting transcriptional changes in eSFs was then studied. Finally, the role of IL-11, a cytokine with a key role in implantation and decidualization, was assessed as a mediator of the SP-facilitated decidualization.

PARTICIPANTS/MATERIALS, SETTING, METHODS

eSFs and endometrial epithelial cells (eECs) were isolated from endometrial biopsies from women of reproductive age undergoing benign gynecologic procedures and maintained in vitro. Assays were conducted to assess whether the treatment of eSFs with SP or SP constituents affects the rate and extent of decidualization in women with and without inflammatory disorders. To characterize the response of the endometrium to SP and SP constituents, RNA was isolated from treated eSFs or eECs and analyzed by RNA sequencing (RNAseq). Secreted factors in conditioned media from treated cells were analyzed by Luminex and ELISA. The role of IL-11 in SP-induced decidualization was assessed through Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas-9-mediated knockout experiments in primary eSFs.

MAIN RESULTS AND THE ROLE OF CHANCE

SP promoted decidualization both in the absence and presence of steroid hormones (P < 0.05 versus vehicle) in a manner that required seminal proteins. Semen amyloids did not promote decidualization and induced weak transcriptomic and secretomic responses in eSFs. In contrast, fractionated SP enriched for seminal microvesicles (MVs) promoted decidualization. IL-11 was one of the most potently SP-induced genes in eSFs and was important for SP-facilitated decidualization.

LARGE SCALE DATA

RNAseq data were deposited in the Gene Expression Omnibus repository under series accession number GSE135640.

LIMITATIONS, REASONS FOR CAUTION

This study is limited to in vitro analyses.

WIDER IMPLICATIONS OF THE FINDINGS

Our results support the notion that SP promotes decidualization, including within eSFs from women with inflammatory disorders. Despite the general ability of amyloids to induce cytokines known to be important for implantation, semen amyloids poorly signaled to eSFs and did not promote their decidualization. In contrast, fractionated SP enriched for MVs promoted decidualization and induced a transcriptional response in eSFs that overlapped with that of SP. Our results suggest that SP constituents, possibly those associated with MVs, can promote decidualization of eSFs in an IL-11-dependent manner in preparation for implantation.

STUDY FUNDING/COMPETING INTEREST(S)

This project was supported by NIH (R21AI116252, R21AI122821 and R01AI127219) to N.R.R. and (P50HD055764) to L.C.G. The authors declare no conflict of interest.

Fluid biomarkers in frontotemporal dementia: past, present and future

The frontotemporal dementia (FTD) spectrum of neurodegenerative disorders includes a heterogeneous group of conditions. However, following on from a series of important molecular studies in the early 2000s, major advances have now been made in the understanding of the pathological and genetic underpinnings of the disease. In turn, alongside the development of novel methodologies for measuring proteins and other molecules in biological fluids, the last 10 years have seen a huge increase in biomarker studies within FTD. This recent past has focused on attempting to develop markers that will help differentiate FTD from other dementias (particularly Alzheimer's disease (AD)), as well as from non-neurodegenerative conditions such as primary psychiatric disorders. While cerebrospinal fluid, and more recently blood, markers of AD have been successfully developed, specific markers identifying primary tauopathies or TDP-43 proteinopathies are still lacking. More focus at the moment has been on non-specific markers of neurodegeneration, and in particular, multiple studies of neurofilament light chain have highlighted its importance as a diagnostic, prognostic and staging marker of FTD. As clinical trials get under way in specific genetic forms of FTD, measures of progranulin and dipeptide repeat proteins in biofluids have become important potential measures of therapeutic response. However, understanding of whether drugs restore cellular function will also be important, and studies of key pathophysiological processes, including neuroinflammation, lysosomal function and synaptic health, are also now becoming more common. There is much still to learn in the fluid biomarker field in FTD, but the creation of large multinational cohorts is facilitating better powered studies and will pave the way for larger omics studies, including proteomics, metabolomics and lipidomics, as well as investigations of multimodal biomarker combinations across fluids, brain imaging and other domains. Here we provide an overview of the past, present and future of fluid biomarkers within the FTD field.

Fluid Biomarkers of Frontotemporal Lobar Degeneration

A timely diagnosis of frontotemporal degeneration (FTD) is frequently challenging due to the heterogeneous symptomatology and poor phenotype-pathological correlation. Fluid biomarkers that reflect FTD pathophysiology could be instrumental in both clinical practice and pharmaceutical trials. In recent years, significant progress has been made in developing biomarkers of neurodegenerative diseases: amyloid-β and tau in cerebrospinal fluid (CSF) can be used to exclude Alzheimer's disease, while neurofilament light chain (NfL) is emerging as a promising, albeit nonspecific, marker of neurodegeneration in both CSF and blood. Gene-specific biomarkers such as PGRN in GRN mutation carriers and dipeptide repeat proteins in C9orf72 mutation carriers are potential target engagement markers in genetic FTD trials. Novel techniques capable of measuring very low concentrations of brain-derived proteins in peripheral fluids are facilitating studies of blood biomarkers as a minimally invasive alternative to CSF. A major remaining challenge is the identification of a biomarker that can be used to predict the neuropathological substrate in sporadic FTD patients.

Reduced Levels of Plasma Lipoxin A4 Are Associated with Post-Stroke Cognitive Impairment

BACKGROUND

Specialized pro-resolving mediators (SPMs) are bioactive lipids derived from n-3 and n-6 polyunsaturated fatty acids. SPMs promote resolution of inflammation and are reduced in Alzheimer's disease. It is unknown whether SPMs are associated with post-stroke cognitive impairment (PSCI).

OBJECTIVE

In the present report, we aimed to study the levels of SPMs in PSCI patients in the acute phase of ischemic stroke.

METHODS

Levels of SPMs in the plasma from 36 patients with PSCI and 33 patients with post-stroke non-cognitive impairment (PSNCI) were measured by enzyme immunoassay.

RESULTS

We found that levels of the SPM lipoxin A4 (LXA4) were significantly reduced in PSCI patients compared with PSNCI patients. Interestingly, the LXA4 levels were positively correlated with Mini-Mental State Examination scores, but not with the National Institutes of Health Stroke Scale scores. Such alteration and correlation were not found in any of the other SPMs analyzed, i.e., including resolvin D1, resolvin D2, and maresin 1.

CONCLUSION

We conclude that the plasma levels of LXA4 were reduced in PSCI patents in the acute phase of ischemic stroke and were correlated to cognitive function.

The Association Between Circulating Klotho and Dipeptidyl Peptidase-4 Activity and Inflammatory Cytokines in Elderly Patients With Alzheimer Disease

Introduction:

Klotho and Dipeptidyl Peptidase-4 (DPP4) are two proteins that modulate inflammatory pathways. We investigated the association between circulating klotho and DPP4 activity and their relationship with inflammatory cytokines, miR-29a, and miR-195 in Alzheimer Disease (AD).

Methods:

This study was conducted on 16 AD patients and 16 healthy age-matched controls. Plasma levels of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β, interleukin-6 (IL-6), klotho, and DPP4 were measured by enzyme-linked immunosorbent assay. Plasma expression of miR-29a and miR-195 were also measured and compared by a real-time polymerase chain reaction.

Results:

There was a significant increase in TNF-α (p=0.006), IL-1β (p=0.012), and IL-6 (p=0.012) levels in the AD subjects compared with controls. Also, we found a decrease in plasma levels of klotho and an increase in plasma levels of DPP4 in the AD group that was not significant compared with the controls. Lower expression of miR-29a (P=0.009) and higher expression of miR-195 (P=0.003) were observed in the AD group that was significant than controls. Further analysis showed a negative correlation between klotho and plasma levels of IL-6 (r=−0.58, p=0.01). Also, there was a positive correlation between plasma DPP4 activity and TNF-α levels (r=0.50, P=0.04) and IL-1β (r=0.62, P=0.01). Likewise, plasma klotho concentration showed a negative correlation with the age of AD subjects (r=−0.56, P=0.02).

Conclusion:

TNF-α, IL-1β, and IL-6 are involved in AD pathophysiology, and dysregulation of DPP4 and klotho may be associated with the inflammatory response of AD. Down-regulation of miR-29a and up-regulation of miR-195 indicated the role of miRNAs in the AD process.

Friend, Foe or Both? Immune Activity in Alzheimer's Disease

Alzheimer's disease (AD) is marked by the presence of amyloid beta (Aβ) plaques, neurofibrillary tangles (NFT), neuronal death and synaptic loss, and inflammation in the brain. AD research has, in large part, been dedicated to the understanding of Aβ and NFT deposition as well as to the pharmacological reduction of these hallmarks. However, recent GWAS data indicates neuroinflammation plays a critical role in AD development, thereby redirecting research efforts toward unveiling the complexities of AD-associated neuroinflammation. It is clear that the innate immune system is intimately associated with AD progression, however, the specific roles of glia and neuroinflammation in AD pathology remain to be described. Moreover, inflammatory processes have largely been painted as detrimental to AD pathology, when in fact, many immune mechanisms such as phagocytosis aid in the reduction of AD pathologies. In this review, we aim to outline the delicate balance between the beneficial and detrimental aspects of immune activation in AD as a more thorough understanding of these processes is critical to development of effective therapeutics for AD.

Neuroinflammation in frontotemporal dementia

Frontotemporal dementia (FTD) refers to a group of progressive neurodegenerative disorders with different pathological signatures, genetic variability and complex disease mechanisms, for which no effective treatments exist. Despite advances in understanding the underlying pathology of FTD, sensitive and specific fluid biomarkers for this disease are lacking. As in other types of dementia, mounting evidence suggests that neuroinflammation is involved in the progression of FTD, including cortical inflammation, microglial activation, astrogliosis and differential expression of inflammation-related proteins in the periphery. Furthermore, an overlap between FTD and autoimmune disease has been identified. The most substantial evidence, however, comes from genetic studies, and several FTD-related genes are also implicated in neuroinflammation. This Review discusses specific evidence of neuroinflammatory mechanisms in FTD and describes how advances in our understanding of these mechanisms, in FTD as well as in other neurodegenerative diseases, might facilitate the development and implementation of diagnostic tools and disease-modifying treatments for FTD.

A review on shared clinical and molecular mechanisms between bipolar disorder and frontotemporal dementia

Mental disorders are highly prevalent and important causes of medical burden worldwide. Co-occurrence of neurological and psychiatric symptoms are observed among mental disorders, representing a challenge for their differential diagnosis. Psychiatrists and neurologists have faced challenges in diagnosing old adults presenting behavioral changes. This is the case for early frontotemporal dementia (FTD) and bipolar disorder. In its initial stages, FTD is characterized by behavioral or language disturbances in the absence of cognitive symptoms. Consequently, patients with the behavioral subtype of FTD (bv-FTD) can be initially misdiagnosed as having a psychiatric disorder, typically major depression disorder (MDD) or bipolar disorder (BD). Bipolar disorder is associated with a higher risk of dementia in older adults and with cognitive impairment, with a subset of patients presents a neuroprogressive pattern during the disease course. No mendelian mutations were identified in BD, whereas three major genetic causes of FTD have been identified. Clinical similarities between BD and bv-FTD raise the question whether common molecular pathways might explain shared clinical symptoms. Here, we reviewed existing data on clinical and molecular similarities between BD and FTD to propose biological pathways that can be further investigated as common or specific markers of BD and FTD.

Recent Developments in TSPO PET Imaging as A Biomarker of Neuroinflammation in Neurodegenerative Disorders

Neuroinflammation is an inflammatory response in the brain and spinal cord, which can involve the activation of microglia and astrocytes. It is a common feature of many central nervous system disorders, including a range of neurodegenerative disorders. An overlap between activated microglia, pro-inflammatory cytokines and translocator protein (TSPO) ligand binding was shown in early animal studies of neurodegeneration. These findings have been translated in clinical studies, where increases in TSPO positron emission tomography (PET) signal occur in disease-relevant areas across a broad spectrum of neurodegenerative diseases. While this supports the use of TSPO PET as a biomarker to monitor response in clinical trials of novel neurodegenerative therapeutics, the clinical utility of current TSPO PET radioligands has been hampered by the lack of high affinity binding to a prevalent form of polymorphic TSPO (A147T) compared to wild type TSPO. This review details recent developments in exploration of ligand-sensitivity to A147T TSPO that have yielded ligands with improved clinical utility. In addition to developing a non-discriminating TSPO ligand, the final frontier of TSPO biomarker research requires developing an understanding of the cellular and functional interpretation of the TSPO PET signal. Recent insights resulting from single cell analysis of microglial phenotypes are reviewed.

LIF, a Novel Myokine, Protects Against Amyloid-Beta-Induced Neurotoxicity via Akt-Mediated Autophagy Signaling in Hippocampal Cells

BACKGROUND

Leukemia inhibitory factor, a novel myokine, is known to be associated with neural function, but the underlying molecular mechanism remains unclear.

METHODS

HT-22 mouse hippocampal cells, primary hippocampal cells, and Drosophila Alzheimer's disease model were used to determine the effect of leukemia inhibitory factor on neurons. Immunoblot analysis and immunofluorescence method were used to analyze biological mechanism.

RESULTS

Leukemia inhibitory factor increased Akt phosphorylation in a phosphoinositide-3-kinase-dependent manner in hippocampal cells. Leukemia inhibitory factor also increased the phosphorylation of the mammalian target of rapamycin and the downstream S6K. Leukemia inhibitory factor stimulated the phosphorylation of signal transducer and activator of transcription via extracellular signal-regulated kinases. Leukemia inhibitory factor increased c-fos expression through both Akt and extracellular signal-regulated kinases. Leukemia inhibitory factor blocked amyloid β-induced neural viability suppression and inhibited amyloid β-induced glucose uptake impairment through the block of amyloid β-mediated insulin receptor downregulation. Leukemia inhibitory factor blocked amyloid β-mediated induction of the autophagy marker, microtubule-associated protein 1A/1B-light chain 3. Additionally, in primary prepared hippocampal cells, leukemia inhibitory factor stimulated Akt and extracellular signal-regulated kinase, demonstrating that leukemia inhibitory factor has physiological relevance in vivo. Suppression of the autophagy marker, light chain 3II, by leukemia inhibitory factor was observed in a Drosophila model of Alzheimer's disease.

CONCLUSIONS

These results demonstrate that leukemia inhibitory factor protects against amyloid β-induced neurotoxicity via Akt/extracellular signal-regulated kinase-mediated c-fos induction, and thus suggest that leukemia inhibitory factor is a potential drug for Alzheimer's disease.

Inflammatory markers of CHMP2B-mediated frontotemporal dementia

Histopathological studies and animal models have suggested an inflammatory component in the pathomechanism of the CHMP2B associated frontotemporal dementia (FTD-3). In this cross-sectional study, serum and cerebrospinal fluid were analyzed for inflammatory markers in CHMP2B mutation carriers. Serum levels of CCL4 were increased throughout life. Serum levels of IL-15, CXCL10, CCL22 and TNF-α were significantly associated with cognitive decline, suggesting a peripheral inflammatory response to neurodegeneration. CSF levels of sTREM2 appeared to increase more rapidly with age in CHMP2B mutation carriers. The identification of a peripheral inflammatory response to disease progression supports the involvement of an inflammatory component in FTD-3.

The role of astrocytes in amyloid production and Alzheimer's disease

Alzheimer's disease (AD) is marked by the presence of extracellular amyloid beta (Aβ) plaques, intracellular neurofibrillary tangles (NFTs) and gliosis, activated glial cells, in the brain. It is thought that Aβ plaques trigger NFT formation, neuronal cell death, neuroinflammation and gliosis and, ultimately, cognitive impairment. There are increased numbers of reactive astrocytes in AD, which surround amyloid plaques and secrete proinflammatory factors and can phagocytize and break down Aβ. It was thought that neuronal cells were the major source of Aβ. However, mounting evidence suggests that astrocytes may play an additional role in AD by secreting significant quantities of Aβ and contributing to overall amyloid burden in the brain. Astrocytes are the most numerous cell type in the brain, and therefore even minor quantities of amyloid secretion from individual astrocytes could prove to be substantial when taken across the whole brain. Reactive astrocytes have increased levels of the three necessary components for Aβ production: amyloid precursor protein, β-secretase (BACE1) and γ-secretase. The identification of environmental factors, such as neuroinflammation, that promote astrocytic Aβ production, could redefine how we think about developing therapeutics for AD.

Imaging and fluid biomarkers in frontotemporal dementia

Frontotemporal dementia (FTD), the second most common type of presenile dementia, is a heterogeneous neurodegenerative disease characterized by progressive behavioural and/or language problems, and includes a range of clinical, genetic and pathological subtypes. The diagnostic process is hampered by this heterogeneity, and correct diagnosis is becoming increasingly important to enable future clinical trials of disease-modifying treatments. Reliable biomarkers will enable us to better discriminate between FTD and other forms of dementia and to predict disease progression in the clinical setting. Given that different underlying pathologies probably require specific pharmacological interventions, robust biomarkers are essential for the selection of patients with specific FTD subtypes. This Review emphasizes the increasing availability and potential applications of structural and functional imaging biomarkers, and cerebrospinal fluid and blood fluid biomarkers in sporadic and genetic FTD. The relevance of new MRI modalities - such as voxel-based morphometry, diffusion tensor imaging and arterial spin labelling - in the early stages of FTD is discussed, together with the ability of these modalities to classify FTD subtypes. We highlight promising new fluid biomarkers for staging and monitoring of FTD, and underline the importance of large, multicentre studies of individuals with presymptomatic FTD. Harmonization in the collection and analysis of data across different centres is crucial for the implementation of new biomarkers in clinical practice, and will become a great challenge in the next few years.

Reduced cerebrospinal fluid concentration of interleukin-12/23 subunit p40 in patients with cognitive impairment

Background

The role of inflammation in Alzheimer’s disease (AD) and other cognitive disorders is unclear. In a well-defined mono-center population, we measured cytokines and chemokines in paired serum and cerebrospinal fluid (CSF) samples.

Methods

Consecutive patients with AD (n = 30), stable mild cognitive impairment (SMCI, n = 11), other dementias (n = 11), and healthy controls (n = 18) were included. None of the subjects was treated with glucocorticoids, cholinesterase inhibitors, or non-steroidal anti-inflammatory drugs. Serum and CSF concentrations of interleukin-6 (IL-6), IL-8, IL-12/23 p40, IL-15, IL-16, vascular endothelial growth factor-A (VEGF-A), and three chemokines were measured using a multiplex panel.

Results

After correction for multiple comparisons, only CSF IL-12/23 p40 concentration differed significantly between the total patient group (n = 52) and controls (n = 18; p = 0.002). Further analyses showed that CSF IL-12/23 p40 concentration was decreased in all patient subgroups (AD, other dementias, and SMCI) compared to healthy controls (p < 0.01, p < 0.05, and p < 0.05, respectively). In the total study population (n = 70), CSF IL-12/23 p40 concentrations correlated positively with CSF concentrations of β-amyloid_1-42 (Aβ_1–42) and phosphorylated tau protein (P-tau) whereas in AD patients (n = 30), CSF IL-12/23 p40 only correlated positively with CSF P-Tau (r = 0.46, p = 0.01).

Conclusions

Most cytokines and chemokines were similar in patients and controls, but CSF IL-12/23 subunit p40 concentration was decreased in patients with cognitive impairment, and correlated with markers of AD disease status. Further studies are needed to evaluate the role of CSF IL-12/23 p40 in other dementias and SMCI.

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.

Role of pro-inflammatory cytokines released from microglia in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder of the brain, which is characterized by the formation of extracellular amyloid plaques (or senile plaques) and intracellular neurofibrillary tangles. However, increasing evidences demonstrated that neuroinflammatory changes, including chronic microgliosis are key pathological components of AD. Microglia, the resident immune cells of the brain, is constantly survey the microenvironment under physiological conditions. In AD, deposition of β-amyliod (Aβ) peptide initiates a spectrum of cerebral neuroinflammation mediated by activating microglia. Activated microglia may play a potentially detrimental role by eliciting the expression of pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) influencing the surrounding brain tissue. Emerging studies have demonstrated that up-regulation of pro-inflammatory cytokines play multiple roles in both neurodegeneration and neuroprotection. Understanding the pro-inflammatory cytokines signaling pathways involved in the regulation of AD is crucial to the development of strategies for therapy. This review will discuss the mechanisms and important role of pro-inflammatory cytokines in the pathogenesis of AD, and the ongoing drug targeting pro-inflammatory cytokine for therapeutic modulation.

Effects of n-3 FA supplementation on the release of proresolving lipid mediators by blood mononuclear cells: the OmegAD study

Specialized proresolving mediators (SPMs) induce resolution of inflammation. SPMs are derivatives of n-3 and n-6 PUFAs and may mediate their beneficial effects. It is unknown whether supplementation with PUFAs influences the production of SPMs. Alzheimer's disease (AD) is associated with brain inflammation and reduced levels of SPMs. The OmegAD study is a randomized, double-blind, and placebo-controlled clinical trial on AD patients, in which placebo or a supplement of 1.7 g DHA and 0.6 g EPA was taken daily for 6 months. Plasma levels of arachidonic acid decreased, and DHA and EPA levels increased after 6 months of n-3 FA treatment. Peripheral blood mononuclear cells (PBMCs) were obtained before and after the trial. Analysis of the culture medium of PBMCs incubated with amyloid-β 1-40 showed unchanged levels of the SPMs lipoxin A4 and resolvin D1 in the group supplemented with n-3 FAs, whereas a decrease was seen in the placebo group. The changes in SPMs showed correspondence to cognitive changes. Changes in the levels of SPMs were positively correlated to changes in transthyretin. We conclude that supplementation with n-3 PUFAs for 6 months prevented a reduction in SPMs released from PBMCs of AD patients, which was associated with changes in cognitive function.

Cerebrospinal fluid proteomics and protein biomarkers in frontotemporal lobar degeneration: Current status and future perspectives

Frontotemporal lobar degeneration (FTLD) comprises a spectrum of rare neurodegenerative diseases with an estimated prevalence of 15-22 cases per 100,000 persons including the behavioral variant of frontotemporal dementia (bvFTD), progressive non-fluent aphasia (PNFA), semantic dementia (SD), FTD with motor neuron disease (FTD-MND), progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS). The pathogenesis of the diseases is still unclear and clinical diagnosis of FTLD is hampered by overlapping symptoms within the FTLD subtypes and with other neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). Intracellular protein aggregates in the brain are a major hallmark of FTLD and implicate alterations in protein metabolism or function in the disease's pathogenesis. Cerebrospinal fluid (CSF) which surrounds the brain can be used to study changes in neurodegenerative diseases and to identify disease-related mechanisms or neurochemical biomarkers for diagnosis. In the present review, we will give an overview of the current literature on proteomic studies in CSF of FTLD patients. Reports of targeted and unbiased proteomic approaches are included and the results are discussed in regard of their informative value about disease pathology and the suitability to be used as diagnostic biomarkers. Finally, we will give some future perspectives on CSF proteomics and a list of candidate biomarkers which might be interesting for validation in further studies. This article is part of a Special Issue entitled: Neuroproteomics: Applications in neuroscience and neurology.

Assessment of CSF Aβ42 as an aid to discriminating Alzheimer's disease from other dementias and mild cognitive impairment: a meta-analysis of 50 studies

Mild Alzheimer's disease (AD) is usually difficult to differentiate from other dementias or mild cognitive impairment (MCI). The aim of our study is to evaluate the clinical importance of cerebrospinal fluid (CSF) β-amyloid 42 (Aβ42) in MCI, AD and other dementias, more specifically: frontotemporal dementia (FTD), dementia with Lewy bodies (DLB), Parkinson's disease (PD) with dementia (PDD) and vascular dementia (VaD). Fifty eligible articles were identified by search of databases including PubMed, EMBASE, Elsevier, Springer Link and the Cochrane Library, from January 1990 to May 2014. The random effects model was used to calculate the standardized mean difference (SMD) with corresponding 95% CI by STATA 9.0 software. The subgroup analyses were made on the method (ELISA, xMAP). We found that CSF Aβ42 concentrations were significantly lower in AD compared to MCI (SMD: -0.68, 95% CI: [-0.80, -0.56], z=11.34, P<0.001), FTD (SMD: -1.09, 95% CI: [-1.41, -0.76], z=6.62, P<0.001), PDD (SMD: -0.75, 95% CI: [-1.39, -0.10], z=2.27, P=0.023), VaD (SMD: -0.95, 95% CI: [-1.30, -0.61], z=5.43, P<0.001). In addition, compared to DLB, Aβ42 concentrations are moderately lower in AD (SMD: -0.27, 95% CI: [-0.51, -0.03], z=2.20, P=0.028). Results from this meta-analysis hinted that CSF Aβ42 is a good biomarker for discriminating Alzheimer's disease from other dementias and MCI.

Does CSF p-tau181 help to discriminate Alzheimer's disease from other dementias and mild cognitive impairment? A meta-analysis of the literature

To evaluate the clinical importance of cerebrospinal fluid (CSF) phosphorylated tau 181 (p-tau181) in mild cognitive impairment (MCI), Alzheimer's disease (AD) and other dementias, more specifically: frontotemporal degeneration (FTD), dementia with Lewy bodies (DLB), vascular dementia (VaD) and Parkinson's disease (PD) with dementia (PDD). Fifty eligible articles were identified by search of databases including PubMed, EMBASE, Elsevier, Springer Link and the Cochrane Library, up to December 2013. The random effects model was used to calculate the standardized mean difference (SMD) with corresponding 95% CI by STATA 9.0 software. The subgroup analyses were made on the methods or PD with dementia. We found that CSF p-tau181 concentrations were significantly higher in AD compared to MCI [SMD: 0.61, 95% CI: (0.46, 0.76), z = 8.07, P < 0.001], FTD [SMD: 1.23, 95% CI: (0.89, 1.56), z = 7.19, P < 0.001], DLB [SMD: 1.08, 95% CI: (0.80, 1.37), z = 7.41, P < 0.001], PDD [SMD: 1.05, 95% CI: (0.02, 2.07), z = 2.00, P = 0.045] and VaD [SMD: 1.28, 95% CI: (0.68, 1.88), z = 4.19, P < 0.001]. Results from this meta-analysis implied that CSF p-tau181 is a good biomarker for discriminating Alzheimer's disease from other dementias and mild cognitive impairment.

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.

Increased metal content in the TDP-43(A315T) transgenic mouse model of frontotemporal lobar degeneration and amyotrophic lateral sclerosis

Disrupted metal homeostasis is a consistent feature of neurodegenerative disease in humans and is recapitulated in mouse models of Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis (ALS) and neuronal ceriod lipofuscinosis. While the definitive pathogenesis of neurodegenerative disease in humans remains to be fully elucidated, disease-like symptoms in the mouse models are all driven by the presence or over-expression of a putative pathogenic protein, indicating an in vivo relationship between expression of these proteins, disrupted metal homeostasis and the symptoms of neuronal failure. Recently it was established that mutant TAR DNA binding protein-43 (TDP-43) is associated with the development of frontotemporal lobar degeneration and ALS. Subsequent development of transgenic mice that express human TDP-43 carrying the disease-causing A315T mutation has provided new opportunity to study the underlying mechanisms of TDP-43-related neurodegenerative disease. We assessed the cognitive and locomotive phenotype of TDP-43 (A315T) mice and their wild-type littermates and also assessed bulk metal content of brain and spinal cord tissues. Metal levels in the brain were not affected by the expression of mutant TDP-43, but zinc, copper, and manganese levels were all increased in the spinal cords of TDP-43 (A315T) mice when compared to wild-type littermates. Performance of the TDP-43 (A315T) mice in the Y-maze test for cognitive function was not significantly different to wild-type mice. By contrast, performance of the TDP-43 (A315T) in the rotarod test for locomotive function was consistently worse than wild-type mice. These preliminary in vivo data are the first to show that expression of a disease-causing form of TDP-43 is sufficient to disrupt metal ion homeostasis in the central nervous system. Disrupted metal ion homeostasis in the spinal cord but not the brain may explain why the TDP-43 (A315T) mice show symptoms of locomotive decline and not cognitive decline.

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.

Fluid biomarkers for diagnosing dementia: rationale and the Canadian Consensus on Diagnosis and Treatment of Dementia recommendations for Canadian physicians

Fluid biomarkers improve the diagnostic accuracy in dementia and provide an objective measure potentially useful as a therapeutic response in clinical trials. The role of fluid biomarkers in patient care is a rapidly evolving field. Here, we provide a review and recommendations regarding the use of fluid biomarkers in clinical practice as discussed at the Fourth Canadian Consensus Conference on the Diagnosis and Treatment of Dementia (CCCDTD4) convened in Montreal, 4 to 5 May 2012. At present, there is no consensus regarding the optimal methodology for conducting quantification of plasma amyloid-beta (Aβ) peptides. In addition, since there is insufficient evidence supporting clinical applications for plasma Aβ-peptide measures, the CCCDTD4 does not recommended plasma biomarkers either for primary care or for specialists. Evidence for CSF Aβ1-42, total tau and phosphorylated tau in the diagnosis of Alzheimer pathology is much stronger, and can be considered at the tertiary care level for selected cases to improve diagnostic certainty, particularly in those cases presenting atypical clinical features.

Brain immune interactions and air pollution: macrophage inhibitory factor (MIF), prion cellular protein (PrP(C)), Interleukin-6 (IL-6), interleukin 1 receptor antagonist (IL-1Ra), and interleukin-2 (IL-2) in cerebrospinal fluid and MIF in serum differentiate urban children exposed to severe vs. low air pollution

Mexico City Metropolitan Area children chronically exposed to high concentrations of air pollutants exhibit an early brain imbalance in genes involved in oxidative stress, inflammation, innate and adaptive immune responses along with accumulation of misfolded proteins observed in the early stages of Alzheimer and Parkinson's diseases. A complex modulation of serum cytokines and chemokines influences children's brain structural and gray/white matter volumetric responses to air pollution. The search for biomarkers associating systemic and CNS inflammation to brain growth and cognitive deficits in the short term and neurodegeneration in the long-term is our principal aim. We explored and compared a profile of cytokines, chemokines (Multiplexing LASER Bead Technology) and Cellular prion protein (PrP(C)) in normal cerebro-spinal-fluid (CSF) of urban children with high vs. low air pollution exposures. PrP(C) and macrophage inhibitory factor (MIF) were also measured in serum. Samples from 139 children ages 11.91 ± 4.2 years were measured. Highly exposed children exhibited significant increases in CSF MIF (p = 0.002), IL6 (p = 0.006), IL1ra (p = 0.014), IL-2 (p = 0.04), and PrP(C) (p = 0.039) vs. controls. MIF serum concentrations were higher in exposed children (p = 0.009). Our results suggest CSF as a MIF, IL6, IL1Ra, IL-2, and PrP(C) compartment that can possibly differentiate air pollution exposures in children. MIF, a key neuro-immune mediator, is a potential biomarker bridge to identify children with CNS inflammation. Fine tuning of immune-to-brain communication is crucial to neural networks appropriate functioning, thus the short and long term effects of systemic inflammation and dysregulated neural immune responses are of deep concern for millions of exposed children. Defining the linkage and the health consequences of the brain / immune system interactions in the developing brain chronically exposed to air pollutants ought to be of pressing importance for public health.

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.

The neglected role of histamine in Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by beta-amyloid plaques accumulation and cognitive impairment. Both environmental factors and heritable predisposition have a role in AD. Histamine is a biogenic monoamine that plays a role in several physiological functions, including induction of inflammatory reactions, wound healing, and regeneration. The Histamine mediates its functions via its 4 G-protein-coupled Histamine H1 receptor (H1R) to histamine H1 receptor (H4R). The histaminergic system has a role in the treatment of brain disorders by the development of histamine receptor agonists, antagonists. The H1R and H4R are responsible for allergic inflammation. But recent studies show that histamine antagonists against H3R and regulation of H2R can be more efficient in AD therapy. In this review, we focus on the role of histamine and its receptors in the treatment of AD, and we hope that histamine could be an effective therapeutic factor in the treatment of AD.

Alzheimer's disease biomarkers: correspondence between human studies and animal models

Alzheimer's disease (AD) represents an escalating global threat as life expectancy and disease prevalence continue to increase. There is a considerable need for earlier diagnoses to improve clinical outcomes. Fluid biomarkers measured from cerebrospinal fluid (CSF) and blood, or imaging biomarkers have considerable potential to assist in the diagnosis and management of AD. An additional important utility of biomarkers is in novel therapeutic development and clinical trials to assess efficacy and side effects of therapeutic interventions. Because many biomarkers are initially examined in animal models, the extent to which markers translate from animals to humans is an important issue. The current review highlights many existing and pipeline biomarker approaches, focusing on the degree of correspondence between AD patients and animal models. The review also highlights the need for greater translational correspondence between human and animal biomarkers.

Inflammation and clinical presentation in neurodegenerative disease: a volatile relationship

A proposed immune mechanism that potentially modifies or exacerbates neurodegenerative disease presentation in older adults has received considerable attention in the past decade, with recent studies demonstrating a strong link between pro-inflammatory markers and neurodegeneration. The overarching aim of the following review is to synthesize recent research that supports a possible relationship between inflammation and clinical features of neurodegenerative diseases, including risk of development, cognitive and clinical correlates, and progression of the specified diseases. Specific emphasis is placed on providing a temporal context for the association between inflammation and neurodegeneration.

Serum antibodies to periodontal pathogens are a risk factor for Alzheimer's disease

BACKGROUND

Chronic inflammation in periodontal disease has been suggested as a potential risk factor in Alzheimer's disease (AD). The purpose of this study was to examine serum antibody levels to bacteria of periodontal disease in participants who eventually converted to AD compared with the antibody levels in control subjects.

METHODS

Serum samples from 158 participants in the Biologically Resilient Adults in Neurological Studies research program at the University of Kentucky were analyzed for immunoglobulin G antibody levels to seven oral bacteria associated with periodontitis, including Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Campylobacter rectus, Treponema denticola, Fusobacterium nucleatum, Tannerella forsythia, and Prevotella intermedia. All 158 participants were cognitively intact at baseline venous blood draw. In all, 81 of the participants developed either mild cognitive impairment (MCI) or AD or both, and 77 controls remained cognitively intact in the years of follow-up. Antibody levels were compared between controls and subjects with AD at baseline draw and after conversion and controls and subjects with MCI at baseline draw and after conversion using the Wilcoxon rank-sum test. AD and MCI participants were not directly compared. Linear regression models were used to adjust for potential confounding.

RESULTS

Antibody levels to F nucleatum and P intermedia were significantly increased (α = 0.05) at baseline serum draw in the patients with AD compared with controls. These results remained significant when controlling for baseline age, Mini-Mental State Examination score, and apolipoprotein epsilon 4 status.

CONCLUSIONS

This study provides initial data that demonstrate elevated antibodies to periodontal disease bacteria in subjects years before cognitive impairment and suggests that periodontal disease could potentially contribute to the risk of AD onset/progression. Additional cohort studies profiling oral clinical presentation with systemic response and AD and prospective studies to evaluate any cause-and-effect association are warranted.