Reactive astrocytes secrete the chaperone HSPB1 to mediate neuroprotection.

Molecular chaperones are protective in neurodegenerative diseases by preventing protein misfolding and aggregation, such as extracellular amyloid plaques and intracellular tau neurofibrillary tangles in Alzheimer's disease (AD). In addition, AD is characterized by an increase in astrocyte reactivity. The chaperone HSPB1 has been proposed as a marker for reactive astrocytes; however, its astrocytic functions in neurodegeneration remain to be elucidated. Here, we identify that HSPB1 is secreted from astrocytes to exert non-cell-autonomous protective functions. We show that in human AD brain, HSPB1 levels increase in astrocytes that cluster around amyloid plaques, as well as in the adjacent extracellular space. Moreover, in conditions that mimic an inflammatory reactive response, astrocytes increase HSPB1 secretion. Concomitantly, astrocytes and neurons can uptake astrocyte-secreted HSPB1, which is accompanied by an attenuation of the inflammatory response in reactive astrocytes and reduced pathological tau inclusions. Our findings highlight a protective mechanism in disease conditions that encompasses the secretion of a chaperone typically regarded as intracellular.

P2X7R influences tau aggregate burden in human tauopathies and shows distinct signalling in microglia and astrocytes.

The purinoceptor P2X7R is a promising therapeutic target for tauopathies, including Alzheimer's disease (AD). Pharmacological inhibition or genetic knockdown of P2X7R ameliorates cognitive deficits and reduces pathological tau burden in mice that model aspects of tauopathy, including mice expressing mutant human frontotemporal dementia (FTD)-causing forms of tau. However, disagreements remain over which glial cell types express P2X7R and therefore the mechanism of action is unresolved. Here, we show that P2X7R protein levels increase in human AD post-mortem brain, in agreement with an upregulation of P2RX7 mRNA observed in transcriptome profiles from the AMP-AD consortium. P2X7R protein increases mirror advancing Braak stage and coincide with synapse loss. Using RNAScope we detect P2RX7 mRNA in microglia and astrocytes in human AD brain, including in the vicinity of senile plaques. In cultured microglia, P2X7R activation modulates the NLRP3 inflammasome pathway by promoting the formation of active complexes and release of IL-1ß. In astrocytes, P2X7R activates NFκB signalling and increases production of the cytokines CCL2, CXCL1 and IL-6 together with the acute phase protein Lcn2. To further explore the role of P2X7R in a disease-relevant context, we expressed wild-type or FTD-causing mutant forms of tau in mouse organotypic brain slice cultures. Inhibition of P2X7R reduces insoluble tau levels without altering soluble tau phosphorylation or synaptic localisation, suggesting a non-cell autonomous role of glial P2X7R on pathological tau aggregation. These findings support further investigations into the cell-type specific effects of P2X7R-targeting therapies in tauopathies.

Proteomics of the astrocyte secretome reveals changes in their response to soluble oligomeric Aß.

Astrocytes associate with amyloid plaques in Alzheimer's disease (AD). Astrocytes react to changes in the brain environment, including increasing concentrations of amyloid-ß (Aß). However, the precise response of astrocytes to soluble small Aß oligomers at concentrations similar to those present in the human brain has not been addressed. In this study, we exposed astrocytes to media from neurons that express the human amyloid precursor protein (APP) transgene with the double Swedish mutation (APPSwe), and which contains APP-derived fragments, including soluble human Aß oligomers. We then used proteomics to investigate changes in the astrocyte secretome. Our data show dysregulated secretion of astrocytic proteins involved in the extracellular matrix and cytoskeletal organization and increase secretion of proteins involved in oxidative stress responses and those with chaperone activity. Several of these proteins have been identified in previous transcriptomic and proteomic studies using brain tissue from human AD and cerebrospinal fluid (CSF). Our work highlights the relevance of studying astrocyte secretion to understand the brain response to AD pathology and the potential use of these proteins as biomarkers for the disease.

Microglial cytokines poison neuronal autophagy via CCR5, a druggable target.

In the prodromal phase of neurodegenerative diseases, microglia switch to an activated state resulting in increased secretion of pro-inflammatory factors. We reported that C - C chemokine ligand 3 (CCL3), C - C chemokine ligand 4 (CCL4) and C - C chemokine ligand 5 (CCL5) contained in the secretome of activated microglia inhibit neuronal autophagy via a non-cell autonomous mechanism. These chemokines bind and activate neuronal C - C chemokine receptor type 5 (CCR5), which, in turn, promotes phosphoinositide 3-kinase (PI3K) - protein kinase B (PKB, or AKT) - mammalian target of rapamycin complex 1 (mTORC1) pathway activation, which inhibits autophagy, thus causing the accumulation of aggregate-prone proteins in the cytoplasm of neurons. The levels of CCR5 and its chemokine ligands are increased in the brains of pre-manifesting Huntington disease (HD) and tauopathy mouse models. CCR5 accumulation might be due to a self-amplifying mechanism, since CCR5 is a substrate of autophagy and CCL5-CCR5-mediated autophagy inhibition impairs CCR5 degradation. Furthermore, pharmacological, or genetic inhibition of CCR5 rescues mTORC1-autophagy dysfunction and improves neurodegeneration in HD and tauopathy mouse models, suggesting that CCR5 hyperactivation is a pathogenic signal driving the progression of these diseases.

Microglial-to-neuronal CCR5 signaling regulates autophagy in neurodegeneration.

In neurodegenerative diseases, microglia switch to an activated state, which results in excessive secretion of pro-inflammatory factors. Our work aims to investigate how this paracrine signaling affects neuronal function. Here, we show that activated microglia mediate non-cell-autonomous inhibition of neuronal autophagy, a degradative pathway critical for the removal of toxic, aggregate-prone proteins accumulating in neurodegenerative diseases. We found that the microglial-derived CCL-3/-4/-5 bind and activate neuronal CCR5, which in turn promotes mTORC1 activation and disrupts autophagy and aggregate-prone protein clearance. CCR5 and its cognate chemokines are upregulated in the brains of pre-manifesting mouse models for Huntington's disease (HD) and tauopathy, suggesting a pathological role of this microglia-neuronal axis in the early phases of these diseases. CCR5 upregulation is self-sustaining, as CCL5-CCR5 autophagy inhibition impairs CCR5 degradation itself. Finally, pharmacological or genetic inhibition of CCR5 rescues mTORC1 hyperactivation and autophagy dysfunction, which ameliorates HD and tau pathologies in mouse models.

Astrocyte adaptation in Alzheimer's disease: a focus on astrocytic P2X7R.

Astrocytes are key homeostatic and defensive cells of the central nervous system (CNS). They undertake numerous functions during development and in adulthood to support and protect the brain through finely regulated communication with other cellular elements of the nervous tissue. In Alzheimer's disease (AD), astrocytes undergo heterogeneous morphological, molecular and functional alterations represented by reactive remodelling, asthenia and loss of function. Reactive astrocytes closely associate with amyloid ß (Aß) plaques and neurofibrillary tangles in advanced AD. The specific contribution of astrocytes to AD could potentially evolve along the disease process and includes alterations in their signalling, interactions with pathological protein aggregates, metabolic and synaptic impairments. In this review, we focus on the purinergic receptor, P2X7R, and discuss the evidence that P2X7R activation contributes to altered astrocyte functions in AD. Expression of P2X7R is increased in AD brain relative to non-demented controls, and animal studies have shown that P2X7R antagonism improves cognitive and synaptic impairments in models of amyloidosis and tauopathy. While P2X7R activation can induce inflammatory signalling pathways, particularly in microglia, we focus here specifically on the contributions of astrocytic P2X7R to synaptic changes and protein aggregate clearance in AD, highlighting cell-specific roles of this purinoceptor activation that could be targeted to slow disease progression.

Astrocytic C-X-C motif chemokine ligand-1 mediates ß-amyloid-induced synaptotoxicity.

BACKGROUND: Pathological interactions between ß-amyloid (Aß) and tau drive synapse loss and cognitive decline in Alzheimer's disease (AD). Reactive astrocytes, displaying altered functions, are also a prominent feature of AD brain. This large and heterogeneous population of cells are increasingly recognised as contributing to early phases of disease. However, the contribution of astrocytes to Aß-induced synaptotoxicity in AD is not well understood. METHODS: We stimulated mouse and human astrocytes with conditioned medium containing concentrations and species of human Aß that mimic those in human AD brain. Medium from stimulated astrocytes was collected and immunodepleted of Aß before being added to naïve rodent or human neuron cultures. A cytokine, identified in unbiased screens of stimulated astrocyte media and in postmortem human AD brain lysates was also applied to neurons, including those pre-treated with a chemokine receptor antagonist. Tau mislocalisation, synaptic markers and dendritic spine numbers were measured in cultured neurons and organotypic brain slice cultures. RESULTS: We found that conditioned medium from stimulated astrocytes induces exaggerated synaptotoxicity that is recapitulated following spiking of neuron culture medium with recombinant C-X-C motif chemokine ligand-1 (CXCL1), a chemokine upregulated in AD brain. Antagonism of neuronal C-X-C motif chemokine receptor 2 (CXCR2) prevented synaptotoxicity in response to CXCL1 and Aß-stimulated astrocyte secretions. CONCLUSIONS: Our data indicate that astrocytes exacerbate the synaptotoxic effects of Aß via interactions of astrocytic CXCL1 and neuronal CXCR2 receptors, highlighting this chemokine-receptor pair as a novel target for therapeutic intervention in AD.

Biomaterials in periapical regeneration after microsurgical endodontics: A narrative review.

BACKGROUND: The objective of this narrative review was to analyze the available scientific evidence regarding the application of biomaterials in endodontic microsurgery and its influence in post-surgical tissue repair. MATERIAL AND METHODS: The review question was Do biomaterials used in endodontic microsurgery influence post-surgical tissue repair and regeneration? Systematic MEDLINE/PubMed review was used to evaluate and present the results. RESULTS: The search yielded 131 references, 82 of which were selected for full text review after reading the abstracts. After a manual search in the references of the articles selected, 52 references were eliminated. Finally, 30 articles were selected. CONCLUSIONS: Bone grafts, membranes and bioceramics, especially MTA, are biomaterials with the ability to stimulate periapical tissue regeneration. This is one of many reason why bioceramics are the best choice as retrograde sealing materials. However, microsurgically treated periapical lesions can heal completely without the need to use bone grafts or membranes. Those techniques are indicated in endodontic microsurgery when additional stimulation of tissue regeneration is required, or when bone collapse needs to be prevented. Key words:Bioactive endodontic cements, endodontic surgery, periapical repair.

Influence of Coronal Preflaring on the Accuracy of Electronic Working Length Determination: Systematic Review and Meta-Analysis.

AIM: To conduct a systematic review and meta-analysis according to the following PICO question: in extracted human permanent teeth, does preflaring, compared with unflared canals, influence the accuracy of WL determination with EAL? MATERIAL AND METHODS: A systematic review was conducted according to the PRISMA checklist, using the following databases: PubMed, Science Direct, Scopus, and Web of Science. Studies related to WL determination using EAL both in preflared and unflared root canals of extracted human teeth were included. The outcome of interest was the accuracy of the electronic WL determination. A quality assessment of the included studies was performed, determining the risk of bias. The meta-analyses were calculated with the 5.4 RevMan software using the inverse variance method with random effects. PROSPERO registration: CRD42021243412. RESULTS: Ten experimental studies fulfilled the inclusion criteria, and most of them found that preflaring increases the accuracy of the EALs in WL determination. The calculated OR was 1.98 (95% CI = 1.65-2.37; p < 0.00001; I2 = 10%), indicating that the determination of WL by EALs is almost twice as accurate in preflared canals. The accuracy of Root ZX in WL determination increases more than three times (OR = 3.25; p < 0.00001). Preflaring with Protaper files significantly increases the accuracy of EALs (OR = 1.76; p < 0.00001). The total risk of bias of the included studies was low. No obvious publication bias was observed. CONCLUSIONS: The results indicate a significant increase in the accuracy of WL determination with EAL after preflaring, doubling the percentage of exact measurements. Preflaring should be recommended as an important step during mechanical enlargement of the root canal, not only because it improves the access of the files to the canal, but also because it allows one to obtain more accurate electronic determinations of WL.

Antibiotics Prescription by Spanish General Practitioners in Primary Dental Care.

The aim of this study was to analyze the antibiotics prescription habits, both prophylactically and therapeutically, of Spanish general dental practitioners in the management of endodontic infections in primary care. Two hundred Spanish general dental practitioners were asked to respond to a survey on indications for antibiotics prescription in the treatment of endodontic infections, being 190 general dentists (95%) included in the study. Data were analyzed using descriptive statistics and the chi-square test. The average duration of antibiotics therapy was 6.5 ± 1.0 days. In patients without medical allergies, most of them (97%) selected amoxicillin as the antibiotic of the first choice, alone (51.1%) or associated with clavulanic acid (45.8%); in patients with penicillin allergies, the drug of choice was clindamycin 300 mg (70%). For cases of symptomatic irreversible pulpitis, 44% of the respondents prescribed antibiotics, in the scenario of prophylactic antibiotic prescription, up to 27% of the general dentists prescribe according to non-current guidelines (1 g 1 h before or 1 g 1 h before and 1 g 1 h after) in non-indicated cases (16% in patients taking oral bisphosphonates). It is necessary to improve the antibiotic prescription habits of Spanish general dentists in endodontics.

Preventing Functional Urinary Incontinence in Hip-Fractured Older Adults Through Patient Education: A Randomized Controlled Trial.

The purpose of this study was to evaluate whether an educational intervention would reduce the incidence of functional urinary incontinence (UI) in older adults with a fall-related hip fracture. The project was conducted as a multicenter randomized controlled trial (RCT). A total of 109 patients that had been admitted to six hospitals in Castilla-La Mancha (Spain) for acute treatment of hip fracture, previously continent and without cognitive impairment, were enrolled and randomly assigned to the experimental group (EG) or the control group (CG). Intervention (on EG): urinary habit training (Nursing Interventions Classifications taxonomy) was performed during hospital stay (second to fourth postoperative day), with a telephonic reinforcement 10 days after discharge. The CG received routine care. Primary outcome measure: incidence of UI. Follow-up: telephone assessment 3 and 6 months after discharge (blinded evaluation). The incidence of UI at 6 months was 49% (CG) versus 25.5% (EG) (relative risk = 0.52, 95% confidence interval [0.3, 0.9]; number necessary to treat = 4). The mean of UI episodes was 0.54 (EG) versus 1.8 (CG), p = .007. The educational intervention prevents the development of UI and decreases the number of episodes in case of appearance, in a statistically significant way.

Smoking and Radiolucent Periapical Lesions in Root Filled Teeth: Systematic Review and Meta-Analysis.

AIM: This systematic review and meta-analysis aimed to investigate the association between smoking habits and the prevalence of radiolucent periapical lesions (RPLs) in root-filled teeth (RFT). METHODS: The Population, Intervention, Comparison, and Outcome (PICO) question was: in adult patients who have RFT, does the absence or presence of a smoking habit affect the prevalence of RPLs associated with RFT? Systematic MEDLINE/PubMed, Wiley Online Database, Web of Science, Scopus, and PRISMA protocol were used to evaluate and present the results. Studies comparing smokers with control non-smoker subjects, including RFT, and providing data on the prevalence of RFT with RPLs, were included. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system was used for certainty in the evidence. The risk of bias was assessed according to Cochrane Collaboration common scheme for bias and ROBINS-I tool. Cumulative meta-analysis was performed with a random effects model. PROSPERO registration code: CRD42020165279. RESULTS: Four studies reported data on inclusion criteria, representing data from 9257 root-filled teeth-4465 from non-smokers and 4792 from smoker patients. The meta-analysis provided an odds ratio indicating a significant association between smoking and higher prevalence of root filled teeth with radiolucent periapical lesions (OR = 1.16; 95% CI = 1.07-1.26; p = 0.0004). The certainty of the literature assessment was moderate per GRADE. The ROBINS-I tool classified three studies as low risk of bias, and the fourth as moderate risk of bias. CONCLUSIONS: Moderate, quality scientific evidence indicates a weak but significant relationship between smoking and the prevalence of RPLs in RFT. Smoking can be considered a negative prognostic factor for the outcome of root canal treatment. Endodontic providers should be aware of the relationship between smoking and persistent apical periodontitis, assessed as RPLs, in RFT.

Cigarette Smoking and Root Filled Teeth Extraction: Systematic Review and Meta-Analysis.

AIM: The aim of this systematic review and meta-analysis was to investigate the possible association between smoking habits and the occurrence of root-filled teeth (RFT) extraction. MATERIAL AND METHODS: The Population, Intervention, Comparison, and Outcome (PICO) question was in adult patients who had RFT, does the absence or presence of smoking habits affect the prevalence of extracted RFT? Systematic MEDLINE/PubMed, Wiley Online Database, Web of Science, and PRISMA protocol was used to evaluate and present the results. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system was used for certainty in the evidence. The risk of bias was assessed according to Cochrane Collaboration common scheme for bias and ROBINS-I tool. Cumulative meta-analysis was performed with a random effects model. PROSPERO registration code: CRD42020165279. RESULTS: After search strategy, 571 articles were recovered, seven were selected for full-text analysis, and two reported data on inclusion criteria, including 516 RFT, 351 in non-smokers, and 165 in smoker subjects. The meta-analysis provided an odds ratio indicating significant association between smoking and the prevalence of extracted RFT (OR = 3.43, 95% CI = 1.17-10.05, p = 0.02, I² = 64%). The certainty of the literature assessment was low per GRADE. Both studies were considered as moderate risk of bias. CONCLUSIONS: Tobacco smoking should be considered a negative prognostic factor for the outcome of root canal treatment, although the quality of the evidence is low. RFT of smoking patients are three times more likely to be extracted. Continuing to smoke after endodontic treatment may increase the risk of treatment failure. However, the overall strength of evidence is low. This must be considered a limitation of the present study and the conclusion should be valued with caution.

Cardiovascular diseases and apical periodontitis: association not always implies causality

BACKGROUND: Several studies published in the last two decades have found an association between the prevalence of apical periodontitis (AP) or root canal treatment (RCT) and cardiovascular diseases (CVDs). However, the demonstration of association does not prove by itself the existence of a cause-effect relationship. Two diseases can appear as statistically related without any of them directly affecting the values of the other, resulting in a non-causal relationship. The aim of this narrative review is to summarize the current state of knowledge regarding the association between AP and CVDs, analysing it according to the Hill's causality criteria. MATERIALS AND METHODS: Epidemiological studies carried out on the association between CVDs and AP or RCT published I n English until 8 December 2019 were identified. For ty-four articles were selected and its results were analysed. RESULTS: Numerous cross-sectional epidemiological studies have found significant relationship between CVDs and AP. The odds ratio values range 1.6 - 5.4. However, other studies have not found significant association. Respect to RCT, some studies found correlation, but others found no association or even found that RCT is a protective factor against CVDs. CONCLUSIONS: The results are inconsistent and a causal relationship between CVDS and endodontic disease cannot be stablished. The risk factors common to both diseases can act as confounding factors, biasing the results. To reach definitive conclusions about the type of association (causal or non-causal) between both diseases, longitudinal epidemiological studies must be carried out to establish the temporal relationship and the dose-response gradient

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Use of ultrasound at a pilot scale to accelerate the ageing of sherry vinegar.

In the present work, the accelerated ageing process of sherry vinegar has been studied at pilot scale by means of the joint application of ultrasound, micro-oxygenation and wood chips (American oak, French oak and Spanish oak). The CIELab parameters have been studied as well as the polyphenolic and volatile content of the aged vinegar samples. Vinegars aged with American oak presented different chromatic characteristics to those aged with French and Spanish oak and a lower polyphenolic and volatile content than the latter ones. On the other hand, Spanish oak generated vinegars with a higher content of volatile compounds and an intermediate polyphenolic profile between those obtained using French and American oak. In addition, the use of ultrasound for a period between 4 and 21 days, generated vinegars with similar characteristics to others that were aged in the traditional way for between 2 and 6 months. It has been demonstrated that the use of ultrasound, combined with micro-oxygenation and chip addition, is a technique which can accelerate the ageing process of vinegars at a pilot scale, so it could be a viable alternative to obtain sherry vinegars aged in a shorter time.

A Microstructure Insight of MTA Repair HP of Rapid Setting Capacity and Bioactive Response.

Mineral trioxide aggregate (MTA) is considered a bioactive endodontic material, which promotes natural mineralization at the material-tooth tissue interface. MTA Repair HP stands out because of the short setting time and the quick and effective bioactive response in vitro. The bioactivity, depens on material composition and microstructure. This work is devoted to analyze MTA Repair HP microstructural features, of both the powder precursor and set material, to get insights into the material physicochemical parameters-functionality performance relationships. Transmission electron microscopy (TEM), and field emission gun scanning electron microscopy (FEG-SEM) coupled with energy-dispersive X-ray (EDX) analyses were performed. X-ray diffraction (XRD) measurements were carried out at different times to investigate setting process. Bioactivity evaluation in vitro was carried out by soaking the processed cement disk in simulated body fluid (SBF). The presented results point out those MTA Repair HP precursor material characteristics of tricalcium silicate particles of nanometric size and high aspect ratio, which provide an elevated surface area and maximized components dispersion of calcium silicate and very reactive calcium aluminate. The MTA Repair HP precursor powder nanostructure and formulation, allows a hydration process comprising silicate hydrate structures, which are very effective to achieve both fast setting and efficient bioactive response.

Autophagy in Astrocytes and its Implications in Neurodegeneration.

Autophagy is a major degradation pathway where double-membrane vesicles called autophagosomes deliver cytoplasmic content to the lysosome. Increasing evidence suggests that autophagy dysfunction contributes to the pathogenesis of neurodegenerative diseases. In addition, misfolded proteins that accumulate in these diseases and constitute a common pathological hallmark are substrates for autophagic degradation. Astrocytes, a major type of glial cells, are emerging as a critical component in most neurodegenerative diseases. This review will summarize the recent efforts to investigate the role that autophagy plays in astrocytes in the context of neurodegenerative diseases. While the field has mostly focused on the implications of autophagy in neurons, autophagy may also be involved in the clearance of disease-related proteins in astrocytes as well as in maintaining astrocyte function, which could impact the cell autonomous and non-cell autonomous contribution of astrocytes to neurodegeneration.

Men and women differ in their perception of gender bias in research institutions.

There is extensive evidence of gender inequality in research leading to insufficient representation of women in leadership positions. Numbers revealing a gender gap in research are periodically reported by national and international institutions but data on perceptions of gender equality within the research community are scarce. In the present study, a questionnaire based on the British Athena Survey of Science, Engineering and Technology (ASSET 2016) was distributed among researchers working in Spain. Consistent with the original UK-based study, women in research perceived a greater degree of gender inequality than men. This difference was consistent from junior to senior positions, within public and private universities as well as research centres, and across all research disciplines. When responses were compared with the existing UK-based questionnaire, researchers in Spain felt that women and men are treated more equally in the workplace, yet they perceived their home departments to be less supportive regarding matters of gender equality. The results of this study provide clear evidence that men and women do not share the same perceptions of gender equality in science and that their differing perceptions are relatively consistent across two major European countries. The fact that men occupy the majority of senior positions while not perceiving the same inequality as women do, may be critical when it comes to ensuring the fair ascent of women to senior positions in an academic system. These data encourage the implementation of measures to ensure that both men and women are aware of gender biases in research.