Targeting NAAA counters dopamine neuron loss and symptom progression in mouse models of parkinsonism.

The lysosomal cysteine hydrolase N-acylethanolamine acid amidase (NAAA) deactivates palmitoylethanolamide (PEA), a lipid-derived PPAR-α agonist that is critically involved in the control of pain and inflammation. In this study, we asked whether NAAA-regulated PEA signaling might contribute to dopamine neuron degeneration and parkinsonism induced by the mitochondrial neurotoxins, 6-hydroxydopamine (6-OHDA) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). In vitro experiments showed that 6-OHDA and MPTP enhanced NAAA expression and lowered PEA content in human SH-SY5Y cells. A similar effect was observed in mouse midbrain dopamine neurons following intra-striatal 6-OHDA injection. Importantly, deletion of the Naaa gene or pharmacological inhibition of NAAA activity substantially attenuated both dopamine neuron death and parkinsonian symptoms in mice treated with 6-OHDA or MPTP. Moreover, NAAA expression was elevated in postmortem brain cortex and premortem blood-derived exosomes from persons with Parkinson's disease compared to age-matched controls. The results identify NAAA-regulated PEA signaling as a molecular control point for dopaminergic neuron survival and a potential target for neuroprotective intervention.

Gender specific decrease of a set of circulating N-acylphosphatidyl ethanolamines (NAPEs) in the plasma of Parkinson's disease patients.

INTRODUCTION: Current markers of Parkinson's disease (PD) fail to detect the early progression of disease state. Conversely, current omics techniques allow the investigation of hundreds of molecules potentially altered by disease conditions. Based on evidence previously collected by our group in a mouse model of PD, we speculated that a particular set of circulating lipids might be significantly altered by the pathology. OBJECTIVES: The aim of current study was to evaluate the potential of a particular set of N-acyl-phosphatidylethanolamines (NAPEs) as potential non-invasive plasma markers of ongoing neurodegeneration from Parkinson's disease in human subjects. METHODS: A panel of seven NAPEs were quantified by LC-MS/MS in the plasma of 587 individuals (healthy controls, n = 319; Parkinson's disease, n = 268); Random Forest classification and statistical modeling was applied to compare Parkinson's disease versus controls. All p-values obtained in different tests were corrected for multiplicity by controlling the false discovery rate (FDR). RESULTS: The results indicate that this panel of NAPEs is able to distinguish female PD patients from the corresponding healthy controls. Further to this, the observed downregulation of these NAPEs is in line with the results in plasma of a mouse model of Parkinson's (6-OHDA). CONCLUSIONS: In the current study we have shown the downregulation of NAPEs in plasma of PD patients and we thus speculate that these lipids might serve as candidate biomarkers for PD. We also suggest a molecular mechanism, explaining our findings, which involves gut microbiota.

Neurovascular Dysfunction in Alzheimer Disease: Assessment of Cerebral Vasoreactivity by Ultrasound Techniques and Evaluation of Circulating Progenitor Cells and Inflammatory Markers.

AIMS: The aims of this study were to assess vascular dysfunction in patients with Alzheimer disease (AD) by investigating cerebral vasomotor reactivity using transcranial Doppler ultrasound (TCD) and to evaluate any correlations between cerebral vasoreactivity and endothelium dysfunction. Moreover, the frequency of circulating progenitor cells (CPCs) and the blood concentration of vascular/inflammatory markers were evaluated. MATERIALS AND METHODS: We recruited 35 AD subjects and 17 age-matched, sex-matched, and education-matched healthy control subjects. Cerebral vasomotor reactivity was assessed by means of the TCD-based breath-holding index test (BHI). The level of CPCs was evaluated by means of flow cytometry from venous blood samples, while blood vascular/inflammatory markers were measured by means of enzyme-linked immunosorbent assay. RESULTS: Both cerebral assay blood flow velocity in the middle cerebral artery (MCAFV) and BHI values were significantly lower in AD subjects than in healthy controls (P<0.05). A positive trend was found between MCAFV and BHI values and Mini-Mental State Evaluation (MMSE) scores. Moreover, the hematopoietic progenitor cells' count was found to be lower in patients with AD than in controls (P<0.05). Finally, a significantly higher expression of the plasma chemokine CCL-2 was observed in AD patients than in healthy controls. CONCLUSIONS: Our results confirm that cerebral hemodynamic deterioration may be a critical marker of cognitive decline. Further studies are needed to investigate the role of circulating CPCs and chemokines as potential contributors to neurovascular dysfunction.

IL-18 Serum Levels and Variants of the Serotonin Transporter Gene Are Related to Awareness of Emotions in Healthy Subjects: A Preliminary Study.

OBJECTIVE: Interaction between the nervous and immune systems may influence emotions, ultimately affecting human health. Cytokines may play a role in developing emotional dysregulation as in alexithymia, a personality construct characterized by the subclinical inability to identify and describe emotions, often associated with several psychiatric and psychosomatic disorders. The proinflammatory cytokine IL-18, with a recognized role in brain functions, may influence serotonin metabolism and appears to be associated with alexithymia. Healthy individuals carrying the long allele (L) of the serotonin transporter gene polymorphic region (5-HTTLPR), and thus having lower concentrations of serotonin in the synaptic cleft, show a greater tendency toward alexithymia, with some gender differences. To explore a potential physiological interaction between IL-18, serotonin neurotransmission, and alexithymia, we investigated whether IL-18 serum levels and 5-HTTLPR are linked to alexithymic traits in healthy subjects. METHODS: We measured IL-18 serum levels in 115 Italian-Caucasian healthy subjects genotyped for 5-HTTLPR allele variants, divided by gender and assessed for alexithymia scores using the 20-item Toronto Alexithymia Scale. RESULTS: IL-18 levels are significantly more elevated in individuals with the LL genotype (n = 25) than in carriers of the short allele (n = 90, p = 0.0073). Specifically, in LL males (n = 11), i.e., the group with the most relevant increase in IL-18, cytokine values positively correlated with difficulty identifying feelings, which is a component of alexithymia (r = 0.634, p = 0.036). CONCLUSIONS: These results indicate a possible novel interaction between IL-18 and the serotoninergic system to mediate emotional unawareness, suggesting putative biological predictors of emotional dysregulation, which in turn can act as a risk factor for a variety of medical conditions in susceptible subjects.

Myeloid dendritic cells are decreased in peripheral blood of Alzheimer's disease patients in association with disease progression and severity of depressive symptoms.

BACKGROUND: Dendritic cells (DCs) are major orchestrators of immune responses and inflammation. They are migratory cells, which may play a role in Alzheimer's disease (AD), as suggested by prior in vitro studies. With the intent to investigate the clinical relevance of DC modifications in vivo, the present study was aimed to evaluate the levels of blood DCs in AD patients, in relation to the progression of the disease, the severity of its symptoms, and the treatment with acetylcholinesterase inhibitors (AChEIs), a class of drugs used to improve cognitive functioning in people with dementia. METHODS: The two main subpopulations of immature blood DCs, namely myeloid (mDCs) and plasmacytoid (pDCs) cells, were evaluated by flow cytometry analysis in 106 AD patients, in comparison with the same cells from 65 individuals with mild cognitive impairment (MCI) and 73 healthy control subjects (HC). The relationship between blood DC levels and symptom severity was also assessed in AD patients, and their blood DC frequency was considered both in the absence or presence of treatment with AChEIs. RESULTS: A significant depletion in blood mDCs was observed in AD patients, as compared to HC and MCI subjects. At variance, pDC levels were comparable among the three groups of subjects. The mDC decrease was evident only after the emergence of AD clinical symptoms, as confirmed by the follow-up analysis of a subgroup of MCI subjects who exhibited a significant decline in mDCs after their conversion to AD. Notably, the mDC decline was inversely correlated in AD patients with the frequency and severity of depressive symptoms. Eventually, the mDC depletion was not observable in patients treated with AChEIs. CONCLUSIONS: Our results provide the first evidence that blood mDC levels are dysregulated in AD. This phenomenon appears mainly linked to AD progression, associated with stronger severity of AD-related symptoms, and influenced by AChEI treatment. Taken all together, these data suggest that blood mDCs may serve as a cell source to test disease-induced and treatment-related changes and support the innovative notion that DCs play a role in AD, as ultimate evidence of the immune system participation in disease progression.

Evaluating the levels of interleukin-1 family cytokines in sporadic amyotrophic lateral sclerosis.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease leading to the death of affected individuals within years. The involvement of inflammation in the pathogenesis of neurodegenerative diseases, including ALS, is increasingly recognized but still not well understood. The aim of this study is to evaluate the levels of inflammation-related IL-1 family cytokines (IL-1ß, IL-18, IL-33, IL-37) and their endogenous inhibitors (IL-1Ra, sIL-1R2, IL-18BP, sIL-1R4) in patients with sporadic ALS (sALS), METHODS: Sera were collected from 144 patients (125 patients were characterized by disease form, duration, and disability, using the revised ALS functional rating scale (ALSFRS-R) and from 40 matched controls. Cerebrospinal fluid (CSF) was collected from 54 patients with sALS and 65 patients with other non-infectious non-oncogenic diseases as controls. Cytokines and inhibitors were measured by commercial ELISA. RESULTS: Among the IL-1 family cytokines tested total IL-18, its endogenous inhibitor IL-18BP, and the active form of the cytokine (free IL-18) were significantly higher in the sALS sera than in controls. No correlation between these soluble mediators and different clinical forms of sALS or the clinical setting of the disease was found. IL-18BP was the only mediator detectable in the CSF of patients. CONCLUSIONS: Among the IL-1 family cytokines, only IL-18 correlates with this disease and may therefore have a pathological role in sALS. The increase of total IL-18 suggests the activation of IL-18-cleaving inflammasome. Whether IL-18 upregulation in circulation of sALS patients is a consequence of inflammation or one of the causes of the pathology still needs to be addressed.

Effects of a novel schizophrenia risk variant rs7914558 at CNNM2 on brain structure and attributional style.

BACKGROUND: A single nucleotide polymorphism (rs7914558) within the cyclin M2 (CNNM2) gene was recently identified as a common risk variant for schizophrenia. The mechanism by which CNNM2 confers risk is unknown. AIMS: To determine the impact of the rs7914558 risk 'G' allele [corrected] on measures of neurocognition, social cognition and brain structure. METHOD: Patients with schizophrenia (n = 400) and healthy controls (n = 160) completed measures of neuropsychological function and social cognition. Structural magnetic resonance imaging data were also acquired from an overlapping sample of Irish healthy controls (n = 159) and an independent sample of Italian patients (n = 82) and healthy controls (n = 39). RESULTS: No effects of genotype on neuropsychological test performance were observed. However, a dosage effect of the risk allele was found for an index of social cognition (i.e. attributional style), such that risk status was associated with reduced self-serving bias across groups (GG>AG>AA, P<0.05). Using voxel-based morphometry to investigate neuroanatomical regions putatively supporting social cognition, risk carriers had relatively increased grey matter volume in the right temporal pole and right anterior cingulate cortex (Pcorrected<0.05) in the Irish healthy controls sample; neuroanatomical associations between CNNM2 and grey matter volume in anterior cingulate cortex were also observed in the Italian schizophrenia and healthy controls samples. CONCLUSIONS: Although the biological role of CNNM2 in schizophrenia remains unknown, these data suggest that this CNNM2 risk variant rs7914558 may have an impact on neural systems relevant to social cognition. How such effects may mediate the relationship between genotype and disease risk remains to be established.

Sample preparation and orthogonal chromatography for broad polarity range plasma metabolomics: application to human subjects with neurodegenerative dementia.

We describe a simple protocol for the preparation and orthogonal hydrophobic/hydrophilic LC-MS/MS analysis of mouse and human plasma samples, which enables the untargeted ("shotgun") or targeted profiling of hydrophilic, amphipathic, and hydrophobic constituents of plasma metabolome. The protocol is rapid, efficient, and reliable, and offers several advantages compared to current procedures. When applied to a training set of human plasma samples, the protocol allowed for the rapid acquisition of full LogP metabolic profiles in plasma samples obtained from cognitively healthy human subjects and age-matched subjects with mild cognitive impairment or Alzheimer's disease (n=15 each). Targeted analyses confirmed these findings, which are consistent with data previously published by other groups.

Increased levels of serum IL-18 are associated with the long-term outcome of severe traumatic brain injury.

OBJECTIVE: A long-lasting neuroinflammatory cascade may lead to the progression of brain damage, favoring neurodegeneration and cognitive impairment in patients with traumatic brain injury (TBI), but the potential mechanisms underlying this sequence of events remain elusive. Here we aimed to evaluate the impact of interleukin (IL)-18, a proinflammatory cytokine elevated in post-acute head injury and associated with neurodegeneration, on the long-term outcome of patients with chronic TBI. METHODS: The serum content of IL-18 was evaluated in 16 patients with severe TBI, during their rehabilitation phase, and in a matched group of 16 healthy controls. The disability of the enrolled patients was evaluated by means of the Glasgow Outcome Scale, Levels of Cognitive Functioning, and the Disability Rating Scale. RESULTS: The circulating levels of IL-18 were significantly increased in chronic TBI patients, as compared to healthy subjects, and correlated with the patients' cognitive impairment and disability severity. CONCLUSIONS: IL-18 may contribute to the long-term outcome and neurodegeneration in TBI patients. Even though further studies are needed to understand the molecular mechanisms underlying the effects of IL-18 on TBI progression and its associated drop in cognitive function, a possible role of this cytokine as a therapeutic target in TBI can be envisaged.

Increased expression of interleukin-18 receptor in blood cells of subjects with mild cognitive impairment and Alzheimer's disease.

Inflammation has been proposed as a leading force in neurodegeneration and Interleukin (IL)-18 is a pro-inflammatory cytokine which is suggested to be implicated in Alzheimer's disease (AD). However, the meaning of the IL-18 participation in this disease is still unclear. Since IL-18 activity is mediated by its heterodimeric receptor complex IL-18Rα/ß, we evaluated the presence of both IL-18R chains on peripheral blood cells of AD patients, as well as in individuals with Mild Cognitive Impairment (MCI), at increased risk to develop AD. More specifically, we compared the levels of CD14(+) monocytes and CD3(+) T-lymphocytes bearing IL-18Rα and ß chains in the two groups of patients with those in healthy control subjects, both before and after in vitro cell treatment with lipopolysaccharide (LPS). While no differences in the levels of monocytes and T-lymphocytes bearing IL-18Rα chain were found among the three groups, either in untreated and LPS-treated conditions, the IL-18Rß chain expression appeared differently regulated in MCI and AD patients, as compared to controls. In particular, the amount of IL-18Rß-bearing monocytes was similar among the three groups at unstimulated conditions, while after LPS treatment it was increased in MCI vs. controls. A significant increase of IL-18Rß-bearing T-lymphocytes was also observed in MCI and AD vs. controls, both in untreated and LPS-stimulated conditions. Our findings indicate that the expression of IL-18R complex on blood cells is perturbed in AD and even more markedly in its preclinical state of MCI, confirming that an increased peripheral activity of IL-18 may be involved in the early phase of AD pathophysiology.

The stimulation of dendritic cells by amyloid beta 1-42 reduces BDNF production in Alzheimer's disease patients.

Dendritic cells (DCs), the main actors of immune responses and inflammation, may play a role in Alzheimer's disease (AD). Recent studies demonstrate that monocyte-derived DCs (MDDCs), generated in vitro in the presence of amyloid ß1-42 peptide (Aß1-42), show a functional alteration and an increased production of inflammatory molecules. Accordingly, MDDCs from AD patients show a more pronounced pro-inflammatory profile than DCs obtained from control subjects. In this study, we aimed at further investigating DC role in AD. Thus, we analyzed the in vitro effect of Aß1-42 treatment on already differentiated DCs from AD patients, as compared to control subjects. We found that Aß1-42 significantly decreases the expression of brain-derived neurotrophic factor (BDNF) in DCs derived from AD patients but not from control subjects. Thus, possibly due to their Aß-induced reduction of neurotrophic support to neurons, DCs from AD patients might contribute to brain damage by playing a part in Aß-dependent neuronal toxicity.

Neuropsychiatric symptoms and interleukin-6 serum levels in acute stroke.

The role of interleukin-6 (IL-6) as a risk factor for developing depressive symptoms, neuropsychological impairment, and related functional and neurological symptom severity during the acute phase of ischemic stroke is still underexplored. Here, the authors assessed this issue, in 48 patients without significant clinical history for major medical illnesses or other factors that promote inflammation, 72 hours after a first-ever acute ischemic stroke. In the acute phase of ischemic stroke, increased IL-6 plays a key role in the onset of depressive disorders, apathy/amotivation, somatic symptoms of depression, and neurological/functional symptoms, resulting in higher disability and poor outcome of stroke patients.

Cause or consequence? The role of IL-1 family cytokines and receptors in neuroinflammatory and neurodegenerative diseases.

Cytokines and receptors of the IL-1 family are key mediators in innate immune and inflammatory reactions in physiological defensive conditions, but are also significantly involved in immune-mediated inflammatory diseases. Here, we will address the role of cytokines of the IL-1 superfamily and their receptors in neuroinflammatory and neurodegenerative diseases, in particular Multiple Sclerosis and Alzheimer's disease. Notably, several members of the IL-1 family are present in the brain as tissue-specific splice variants. Attention will be devoted to understanding whether these molecules are involved in the disease onset or are effectors of the downstream degenerative events. We will focus on the balance between the inflammatory cytokines IL-1ß and IL-18 and inhibitory cytokines and receptors, in view of future therapeutic approaches.

Schizophrenia and Glutathione: A Challenging Story.

Schizophrenia (SZ) is a devastating mental illness with a complex and heterogeneous clinical state. Several conditions like symptoms, stage and severity of the disease are only some of the variables that have to be considered to define the disorder and its phenotypes. SZ pathophysiology is still unclear, and the diagnosis is currently relegated to the analysis of clinical symptoms; therefore, the search for biomarkers with diagnostic relevance is a major challenge in the field, especially in the era of personalized medicine. Though the mechanisms implicated in SZ are not fully understood, some processes are beginning to be elucidated. Oxidative stress, and in particular glutathione (GSH) dysregulation, has been demonstrated to play a crucial role in SZ pathophysiology. In fact, glutathione is a leading actor of oxidative-stress-mediated damage in SZ and appears to reflect the heterogeneity of the disease. The literature reports differing results regarding the levels of glutathione in SZ patients. However, each GSH state may be a sign of specific symptoms or groups of symptoms, candidating glutathione as a biomarker useful for discriminating SZ phenotypes. Here, we summarize the literature about the levels of glutathione in SZ and analyze the role of this molecule and its potential use as a biomarker.

High serum levels of transforming growth factor ß1 are associated with increased cortical thickness in cingulate and right frontal areas in healthy subjects.

BACKGROUND: Transforming growth factor ß (TGF-ß) is a cytokine having multiple functions in the central nervous system such as promoting repair mechanisms in degenerative diseases and stroke. To date, however, its neuroprotective effects in non-disease conditions have not been studied METHODS: With the aim of exploring the relationship between peripheral TGF-ß1 expression and brain structural integrity, 70 healthy participants underwent high-resolution structural T1-weighted magnetic resonance imaging scans and blood sampling. Data were processed to obtain brain cortical thickness and serum concentrations of TGF-ß1. We investigated the correlation between TGF-ß1 and cortical thickness using both region-of-interest- and vertex-based approaches. FINDINGS: Region-of-interest-based analysis of the cortical mantle showed a correlation between TGF-ß1 serum concentrations and cortical thickness bilaterally in cingulate and right frontal and temporal areas. Similar results emerged in the vertex-based analysis, where significant correlations were found bilaterally in cingulate and right frontal cortices. CONCLUSIONS: These results suggest that TGF-ß1, through its role in down-regulating inflammatory processes, might have a beneficial effect on the structural integrity of the brain in physiological states.

Elevated levels of circulating IL-18BP and perturbed regulation of IL-18 in schizophrenia.

BACKGROUND: The pleiotropic pro-inflammatory cytokine Interleukin (IL)-18 has been proposed to play a role in schizophrenia, since elevated circulating levels of its protein and altered frequencies of genetic variants in its molecular system are reported in schizophrenic patients. METHODS: We analyzed 77 patients with schizophrenia diagnosis (SCZ) and 77 healthy control subjects (HC) for serum concentration of both IL-18 and its natural inhibitor, the IL-18 binding protein (IL-18BP). RESULTS: We confirmed that serum levels of total IL-18 are significantly increased in SCZ, as compared to HC. However, due to a highly significant increase in levels of circulating IL-18BP in SCZ, as compared to HC, the levels of free, bioactive IL-18 are not significantly different between the two groups. In addition, the relationships between the levels of IL-18 and its inhibitor, as well as between the two molecules and age appear dissimilar for SCZ and HC. In particular, the elevated levels of IL-18BP, likely a consequence of the body's attempt to counteract the early prominent inflammation which characterizes schizophrenia, are maintained in earlier and later stages of the disease. However, the IL-18BP elevation appears ineffective to balance the IL-18 system in younger SCZ patients, while in older patients the levels of circulating bioactive IL-18 are comparable to those of HC, if not lower. CONCLUSIONS: In conclusion, these findings indicate that the IL-18 system is perturbed in schizophrenia, supporting the idea that this pro-inflammatory cytokine might be part of a pathway of genetic and environmental components for vulnerability to the disease.

A single intraperitoneal injection of endotoxin in rats induces long-lasting modifications in behavior and brain protein levels of TNF-α and IL-18.

BACKGROUND: Systemic inflammation might cause neuronal damage and sustain neurodegenerative diseases and behavior impairment, with the participation of pro-inflammatory cytokines, like tumor necrosis factor (TNF)-α and interleukin (IL)-18. However, the potential contribution of these cytokines to behavioral impairment in the long-term period has not been fully investigated. METHODS: Wistar rats were treated with a single intraperitoneal injection of LPS (5 mg/kg) or vehicle. After 7 days and 10 months, the animal behavior was evaluated by testing specific cognitive functions, as mnesic, discriminative, and attentional functions, as well as anxiety levels. Contextually, TNF-α and IL-18 protein levels were measured by ELISA in defined brain regions (that is, frontal cortex, hippocampus, striatum, cerebellum, and hypothalamus). RESULTS: Behavioral testing demonstrated a specific and persistent cognitive impairment characterized by marked deficits in reacting to environment modifications, possibly linked to reduced motivational or attentional deficits. Concomitantly, LPS induced a TNF-α increase in the hippocampus and frontal cortex (from 7 days onward) and cerebellum (only at 10 months). Interestingly, LPS treatment enhanced IL-18 expression in these same areas only at 10 months after injection. CONCLUSIONS: Overall, these results indicate that the chronic neuroinflammatory network elicited by systemic inflammation involves a persistent participation of TNF-α accompanied by a differently regulated contribution of IL-18. This leads to speculation that, though with still unclear mechanisms, both cytokines might take part in long-lasting modifications of brain functions, including behavioral alteration.

Increased levels of serum MAP-2 at 6-months correlate with improved outcome in survivors of severe traumatic brain injury.

OBJECTIVE: To evaluate microtubule-associated proteins (MAP-2), a dendritic marker of both acute damage and chronic neuronal regeneration after injury, in serum of survivors after severe TBI and examine the association with long-term outcome. METHODS: Serum concentrations of MAP-2 were evaluated in 16 patients with severe TBI (Glasgow Coma Scale score [GCS] ≤ 8) 6 months post-injury and in 16 controls. Physical and cognitive outcomes were assessed, using the Glasgow Outcome Scale Extended (GOSE) and Levels of Cognitive Functioning Scale (LCFS), respectively. RESULTS: Severe TBI patients had significantly higher serum MAP-2 concentrations than normal controls with no history of TBI (p = 0.008) at 6 months post-injury. MAP-2 levels correlated with the GOSE (r = 0.58, p = 0.02) and LCFS (r = 0.65, p = 0.007) at month 6. Significantly lower serum levels of MAP-2 were observed in patients in a vegetative state (VS) compared to non-VS patients (p < 0.05). A trend tracking the level of consciousness was observed. CONCLUSIONS: Severe TBI results in a chronic release of MAP-2 into the peripheral circulation in patients with higher levels of consciousness, suggesting that remodelling of synaptic junctions and neuroplasticity processes occur several months after injury. The data indicate MAP-2 as a potential marker for emergence to higher levels of cognitive function.

IL-33 and IL-10 Serum Levels Increase in MCI Patients Following Homotaurine Treatment.

Homotaurine is a potential therapeutic compound for treatment of Alzheimer's disease (AD), but its efficacy is still under investigation. Emerging data have shown that other than neuroprotective, homotaurine is endowed with anti-inflammatory activities, though with still unclear underlying mechanisms. Inflammation plays a critical role in the pathogenesis of AD and we previously suggested that homotaurine supplementation in patients with amnestic mild cognitive impairment (MCI) plays beneficial effects associated to a decrease in the circulating levels of the pro-inflammatory cytokine IL-18. Here we report that MCI patients supplemented with homotaurine for 12 months show elevated serum levels of IL-10 and IL-33, as compared to baseline, in addition to the described IL-18 decrease. Furthermore, we observed a significant positive correlation between IL-10 and IL-33 levels after treatment but not at the baseline, underlining the effectiveness of the compound in modulating both cytokines in an inter-related fashion and in regulating the pro/anti-inflammation balance. Furthermore, the elevation of both IL-10 and IL-33 is significantly associated with an improvement of episodic memory of treated patients, as measured by the Delayed Verbal Ray Test. In conclusion, our results confirm that homotaurine treatment exerts an overall anti-inflammatory action in MCI patients, based not only on the down-regulation of pro-inflammatory IL-18, but also on up-regulation of the anti-inflammatory IL-33 and IL-10 cytokines, which in turn are associated with an amelioration of patient's cognitive functions. Future studies should be addressed to investigate the molecular mechanisms of homotaurine anti-inflammatory activity and its therapeutic exploitation in early AD.

Identification of Genetic Networks Reveals Complex Associations and Risk Trajectory Linking Mild Cognitive Impairment to Alzheimer's Disease.

Amnestic mild cognitive impairment (aMCI) and sporadic Alzheimer's disease (AD) are multifactorial conditions resulting from a complex crosstalk among multiple molecular and biological processes. The present study investigates the association of variants localized in genes and miRNAs with aMCI and AD, which may represent susceptibility, prognostic biomarkers or multi-target treatment options for such conditions. We included 371 patients (217 aMCI and 154 AD) and 503 healthy controls, which were genotyped for a panel of 120 single nucleotide polymorphisms (SNPs) and, subsequently, analyzed by statistical, bioinformatics and machine-learning approaches. As a result, 21 SNPs were associated with aMCI and 13 SNPs with sporadic AD. Interestingly, a set of variants shared between aMCI and AD displayed slightly higher Odd Ratios in AD with respect to aMCI, highlighting a specific risk trajectory linking aMCI to AD. Some of the associated genes and miRNAs were shown to interact within the signaling pathways of APP (Amyloid Precursor Protein), ACE2 (Angiotensin Converting Enzyme 2), miR-155 and PPARG (Peroxisome Proliferator Activated Receptor Gamma), which are known to contribute to neuroinflammation and neurodegeneration. Overall, results of this study increase insights concerning the genetic factors contributing to the neuroinflammatory and neurodegenerative mechanisms underlying aMCI and sporadic AD. They have to be exploited to develop personalized approaches based on the individual genetic make-up and multi-target treatments.