The Role of Alpha-Synuclein in Synucleinopathy: Impact on Lipid Regulation at Mitochondria-ER Membranes.

The protein alpha-synuclein (αSyn) plays a critical role in the pathogenesis of synucleinopathy, which includes Parkinson's disease and multiple system atrophy, and mounting evidence suggests that lipid dyshomeostasis is a critical phenotype in these neurodegenerative conditions. Previously, we identified that αSyn localizes to mitochondria-associated endoplasmic reticulum membranes (MAMs), temporary functional domains containing proteins that regulate lipid metabolism, including the de novo synthesis of phosphatidylserine. In the present study, we have analyzed the lipid composition of postmortem human samples, focusing on the substantia nigra pars compacta of Parkinson's disease and controls, as well as three less affected brain regions of Parkinson's donors. To further assess synucleinopathy-related lipidome alterations, similar analyses were performed on the striatum of multiple system atrophy cases. Our data show region-and disease-specific changes in the levels of lipid species. Specifically, our data revealed alterations in the levels of specific phosphatidylserine species in brain areas most affected in Parkinson's disease. Some of these alterations, albeit to a lesser degree, are also observed multiples system atrophy. Using induced pluripotent stem cell-derived neurons, we show that αSyn contributes to regulating phosphatidylserine metabolism at MAM domains, and that αSyn dosage parallels the perturbation in phosphatidylserine levels. Our results support the notion that αSyn pathophysiology is linked to the dysregulation of lipid homeostasis, which may contribute to the vulnerability of specific brain regions in synucleinopathy. These findings have significant therapeutic implications.

IL-1RA Disrupts ATP Activation of P2RX7 in Human Monocyte-Derived Microglia-like Cells.

The immune system has a dynamic role in neurodegenerative diseases, and purinergic receptors allow immune cells to recognize neuronal signaling, cell injury, or stress. Purinergic Receptor 7 (P2RX7) can modulate inflammatory cascades and its expression is upregulated in Alzheimer's disease (AD) brain tissue. P2RX7 expression is enriched in microglia, and elevated levels are found in microglia surrounding amyloid-beta plaques in the brain. While P2RX7 is thought to play a role in neurodegenerative diseases, how it modulates pathology and disease progression is not well understood. Here, we utilize a human monocyte-derived microglia-like cell (MDMi) model to interrogate P2RX7 activation and downstream consequences on microglia function. By using MDMi derived from human donors, we can examine how human donor variation impacts microglia function. We assessed P2RX7-driven IL1ß and IL18 production and amyloid-beta peptide 1-42 (Aß1-42) uptake levels. Our results show that ATP-stimulation of MDMi triggers upregulation of IL1ß and IL18 expression. This upregulation of cytokine gene expression is blocked with the A740003 P2RX7 antagonist. We find that high extracellular ATP conditions also reduced MDMi capacity for Aß1-42 uptake, and this loss of function is prevented through A740003 inhibition of P2RX7. In addition, pretreatment of MDMi with IL-1RA limited ATP-driven IL1ß and IL18 gene expression upregulation, indicating that ATP immunomodulation of P2RX7 is IL-1R dependent. Aß1-42 uptake was higher with IL-1RA pretreatment compared to ATP treatment alone, suggesting P2RX7 regulates phagocytic engulfment through IL-1 signaling. Overall, our results demonstrate that P2RX7 is a key response protein for high extracellular ATP in human microglia-like cells, and its function can be modulated by IL-1 signaling. This work opens the door to future studies examining anti-IL-1 biologics to increase the clearance of amyloid-beta.

Clonal CD8 T Cells Accumulate in the Leptomeninges and Communicate with Microglia in Human Neurodegeneration.

Murine studies have highlighted a crucial role for immune cells in the meninges in surveilling the central nervous system (CNS) and influencing neuroinflammation. However, how meningeal immunity is altered in human neurodegeneration and its effects on CNS inflammation is understudied. We performed the first single-cell analysis of the transcriptomes and T cell receptor (TCR) repertoire of 104,635 immune cells from 55 postmortem human brain and leptomeningeal tissues from donors with neurodegenerative diseases including amyotrophic lateral sclerosis, Alzheimer's disease, and Parkinson's disease. RNA and TCR sequencing from paired leptomeninges and brain allowed us to perform lineage tracing to identify the spatial trajectory of clonal T cells in the CNS and its borders. We propose that T cells activated in the brain emigrate to and establish residency in the leptomeninges where they likely contribute to impairments in lymphatic drainage and remotely to CNS inflammation by producing IFNγ and other cytokines. We identified regulatory networks local to the meninges including NK cell-mediated CD8 T cell killing which likely help to control meningeal inflammation. Collectively, these findings provide not only a foundation for future studies into brain border immune surveillance but also highlight important intercellular dynamics that could be leveraged to modulate neuroinflammation.

Distinct microglial transcriptomic signatures within the hippocampus.

Microglia, the resident immune cells of the brain, are crucial in the development of the nervous system. Recent evidence demonstrates that microglia modulate adult hippocampal neurogenesis by inhibiting cell proliferation of neural precursors and survival both in vitro and in vivo, thus maintaining a balance between cell division and cell death in the neural stem cell pool. There are increasing reports suggesting these microglia found in neurogenic niches differ from their counterparts in non-neurogenic areas. Here, we present evidence that hippocampal microglia exhibit transcriptomic heterogeneity, with some cells expressing genes associated with neurogenesis. By comprehensively profiling myeloid lineage cells in the hippocampus using single cell RNA-sequencing, we have uncovered a small, yet distinct population of microglia which exhibit depletion in genes associated with homeostatic microglia and enrichment of genes associated with phagocytosis. Intriguingly, this population also expresses a gene signature with substantial overlap with previously characterized phenotypes, including disease associated microglia (DAM), a particularly unique and compelling microglial state.

Clonal CD8 T cells in the leptomeninges are locally controlled and influence microglia in human neurodegeneration.

Recent murine studies have highlighted a crucial role for the meninges in surveilling the central nervous system (CNS) and influencing CNS inflammation. However, how meningeal immunity is altered in human neurodegeneration and its potential effects on neuroinflammation is understudied. In the present study, we performed single-cell analysis of the transcriptomes and T cell receptor repertoire of 72,576 immune cells from 36 postmortem human brain and leptomeninges tissues from donors with neurodegenerative diseases including amyotrophic lateral sclerosis, Alzheimer's disease, and Parkinson's disease. We identified the meninges as an important site of antigen presentation and CD8 T cell activation and clonal expansion and found that T cell activation in the meninges is a requirement for infiltration into the CNS. We further found that natural killer cells have the potential to negatively regulate T cell activation locally in the meninges through direct killing and are one of many regulatory mechanisms that work to control excessive neuroinflammation.

APOE and immunity: Research highlights.

INTRODUCTION: At the Alzheimer's Association's APOE and Immunity virtual conference, held in October 2021, leading neuroscience experts shared recent research advances on and inspiring insights into the various roles that both the apolipoprotein E gene (APOE) and facets of immunity play in neurodegenerative diseases, including Alzheimer's disease and other dementias. METHODS: The meeting brought together more than 1200 registered attendees from 62 different countries, representing the realms of academia and industry. RESULTS: During the 4-day meeting, presenters illuminated aspects of the cross-talk between APOE and immunity, with a focus on the roles of microglia, triggering receptor expressed on myeloid cells 2 (TREM2), and components of inflammation (e.g., tumor necrosis factor α [TNFα]). DISCUSSION: This manuscript emphasizes the importance of diversity in current and future research and presents an integrated view of innate immune functions in Alzheimer's disease as well as related promising directions in drug development.

Agreement between force and deceleration measures during backward somersault landings.

This study examined the agreement between force platform and inertial measurement unit (IMU) measures of backward somersault landings. Seven female gymnasts performed three trials, taking off from a 90 cm vaulting box and using competition landing technique. Two force platforms (1000 Hz) covered with a 6.4 cm thick carpeted landing surface measured the ground reaction forces. One inertial measurement unit (500 Hz) fixed on the second thoracic vertebra measured peak resultant deceleration of the gymnast. Measurement agreement between vertical and resultant peak force measures, and resultant peak force and peak deceleration was assessed using mean differences, Pearson's correlation, and Cohen's effect size (ES) statistics. There was perfect measurement agreement between vertical and resultant peak forces (R = 1.0, p < 0.001; ES = 0.005), but only moderate measurement agreement between resultant peak force and peak resultant deceleration (Mean Difference = -2.16%, R = 0.4, p = ns; ES = 0.121). Backward somersault landings can be assessed using either uni-axial or tri-axial force platforms to measure ground impact load/force, as the landing movements are almost purely vertical. However, force measures are not the same as peak resultant decelerations from IMUs which give an indication of impact shock. Landing load/shock measures are potentially important for injury prevention.

Alzheimer's Disease Genetics: A Dampened Microglial Response?

Alzheimer's disease (AD) is a debilitating age-related neurodegenerative condition. Unbiased genetic studies have implicated a central role for microglia, the resident innate immune cells of the central nervous system, in AD pathogenesis. On-going efforts are clarifying the biology underlying these associations and the microglial pathways that are dysfunctional in AD. Several genetic risk factors converge to decrease the function of activating microglial receptors and increase the function of inhibitory receptors, resulting in a seemingly dampened microglial phenotype in AD. Moreover, many of these microglial proteins that are genetically associated with AD appear to interact and share pathways or regulatory mechanisms, presenting several points of convergence that may be strategic targets for therapeutic intervention. Here, we review some of these studies and their implications for microglial participation in AD pathogenesis.

The use of inertial measurement units to quantify forearm loading and symmetry during gymnastics vault training sessions.

The upper limbs are important in gymnastics vaulting, as the success of the flight phase is dependent on a quick and forceful push-off from the vault. This places the upper limbs under stress, which has been associated with pain and injury. This study aimed to quantify forearm segmental loading and symmetry when performing foundation to advanced-level vaulting skills during training. Twelve advanced-level artistic gymnasts (female, n = 6; male, n = 6) wore bilaterally forearm-mounted inertial measurement units while completing their vaulting sessions. The peak resultant acceleration for the leading and non-leading forearms during contact were calculated. Female gymnasts performed variations of Yurchenko vaults, while male gymnasts performed Handspring and Tsukahara vaults. Descriptive statistics (median and inter-quartile range), symmetry index scores, and total session impact load (measure of cumulative loading) were calculated between the lead and non-lead forearms. High asymmetrical loading was identified for some Yurchenko, Handspring, and Tsukahara vaults, with large variations identified between gymnasts. Some gymnasts experienced greater loading at their lead forearm, while others experienced greater loading at their non-lead forearm. Results indicate that limb loading patterns in advanced gymnastics are highly individualised, indicating that individual analysis is needed to identify gymnasts (or limbs) at an increased risk for overuse injury.

Linking the region-specific tissue microstructure to the biaxial mechanical properties of the porcine left anterior descending artery.

Coronary atherosclerosis is the main cause of death worldwide. Advancing the understanding of coronary microstructure-based mechanics is fundamental for the development of therapeutic tools and surgical procedures. Although the passive biaxial properties of the coronary arteries have been extensively explored, their regional differences and the relationship between tissue microstructure and mechanics have not been fully characterized. In this study, we characterized the passive biaxial mechanical properties and microstructural properties of the proximal, medial, and distal regions of the porcine left anterior descending artery (LADA). We also attempted to relate the biaxial stress-stretch response of the LADA and its respective birefringent responses to the polarized light for obtaining information about the load-dependent microstructural variations. We found that the LADA extensibility is reduced in the proximal-to-distal direction and that the medial region exhibits more heterogeneous mechanical behavior than the other two regions. We have also observed highly dynamic microstructural behavior where fiber families realign themselves depending on loading. In addition, we found that the microstructure of the distal region exhibited highly aligned fibers along the longitudinal axis of the artery. To verify this microstructural feature, we imaged the LADA specimens with multi-photon microscopy and observed that the adventitia microstructure transitioned from a random fiber network in the proximal region to highly aligned fibers in the distal region. Our findings could offer new perspectives for understanding coronary mechanics and aid in the development of tissue-engineered vascular grafts, which are currently limited due to their mismatch with native tissue in terms of mechanical properties and microstructural features. STATEMENT OF SIGNIFICANCE: The tissue biomechanics of coronary arteries is fundamental for the development of revascularization techniques such as coronary artery bypass. These therapeutics require a deep understanding of arterial mechanics, microstructure, and mechanobiology to prevent graft failure and reoperation. The present study characterizes the unique regional mechanical and microstructural properties of the porcine left anterior descending artery using biaxial testing, polarized-light imaging, and confocal microscopy. This comprehensive characterization provides an improved understanding of the collagen/elastin architecture in response to mechanical loads using a region-specific approach. The unique tissue properties obtained from this study will provide guidance for the selection of anastomotic sites in coronary artery bypass grafting and for the design of tissue-engineered vascular grafts.

GW5074 Increases Microglial Phagocytic Activities: Potential Therapeutic Direction for Alzheimer's Disease.

Microglia, the resident immune cells of the central nervous system (CNS), are responsible for maintaining homeostasis in the brain by clearing debris and are suggested to be inefficient in Alzheimer's Disease (AD), a progressive neurodegenerative disorder for which there is no disease-modifying drug. Besides pathological approaches, unbiased evidence from genome-wide association studies (GWAS) and gene network analysis implicate genes expressed in microglia that reduce phagocytic ability as susceptibility genes for AD. Thus, a central feature toward AD therapy is to increase the microglial phagocytic activities while maintaining synaptic integrity. Here, we developed a robust unbiased high content screening assay to identify potential therapeutics which can reduce the amyloid-beta (Aß1-42) load by increasing microglial uptake ability. Our screen identified the small-molecule GW5074, an inhibitor of c-RAF, a serine/threonine kinase, which significantly increased the Aß1-42 clearance activities in human monocyte-derived microglia-like (MDMi) cells, a microglia culture model that recapitulates many genetic and phenotypic aspects of human microglia. Notably, GW5074 was previously reported to be neuroprotective for cerebellar granule cells and cortical neurons. We found that GW5074 significantly increased the expression of key AD-associated microglial molecules known to modulate phagocytosis: TYROBP, SIRPß1, and TREM2. Our results demonstrated that GW5074 is a potential therapeutic for AD, by targeting microglia.

The aging immune system in Alzheimer's and Parkinson's diseases.

The neurodegenerative diseases Alzheimer's disease (AD) and Parkinson's disease (PD) both have a myriad of risk factors including genetics, environmental exposures, and lifestyle. However, aging is the strongest risk factor for both diseases. Aging also profoundly influences the immune system, with immunosenescence perhaps the most prominent outcome. Through genetics, mouse models, and pathology, there is a growing appreciation of the role the immune system plays in neurodegenerative diseases. In this review, we explore the intersection of aging and the immune system in AD and PD.

Genotype-phenotype correlation of T-cell subtypes reveals senescent and cytotoxic genes in Alzheimer's disease.

Recent studies identifying expression quantitative trait loci (eQTLs) in immune cells have uncovered important links between disease risk alleles and gene expression trends in monocytes, T cells and other cell types. However, these studies are generally done with young, healthy subjects, limiting the utility of their findings for age-related conditions such as Alzheimer's disease (AD). We have performed RNA sequencing on four T-cell subsets in genome-wide genotyped and well-characterized AD subjects and age- and sex-matched controls from the Religious Orders Study/Memory and Aging Project. We correlated gene expression data with AD neuropathological traits and with single-nucleotide polymorphisms to detect eQTLs. We identified several significant genes involved in T-cell senescence and cytotoxicity, consistent with T-cell RNA sequencing studies in aged/AD cohorts. We identified unexpected eQTLs previously associated with neuropsychiatric disease traits. Finally, we discovered that pathways related to axon guidance and synaptic function were enriched among trans-eQTLs in coding regions of the genome. Our data strengthen the potential link between T-cell senescence and age-related neurodegenerative disease. In addition, our eQTL data suggest that T-cell phenotypes may influence neuropsychiatric disorders and can be influenced by genes involved in neurodevelopmental processes.

Prognostic factors for persistent pain after a distal radius fracture: a systematic review.

Introduction: The aim of this systematic review was to synthesize the evidence regarding prognostic factors for persistent pain, including Complex Regional Pain Syndrome (CRPS), after a distal radius fracture (DRF), a common condition after which persistent pain can develop. Methods: Medline, Pubmed, Embase, Psychinfo, CINAHL, BNI, AMED and the Cochrane Register of Clinical Trials were searched from inception to May 2021 for prospective longitudinal prognostic factor studies investigating persistent pain in adults who had sustained a DRF. The Quality in Prognostic Studies (QUIPS) tool and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) framework were used to assess the strength of evidence. Results: A search yielded 440 studies of which 7 studies met full eligibility criteria. From five studies we found low evidence for high baseline pain or an ulnar styloid fracture as prognostic factors for persistent pain, and very low evidence for diabetes or older age. From two studies, investigating an outcome of CRPS, there was low evidence for high baseline pain, slow reaction time, dysynchiria, swelling and catastrophising as prognostic factors, and very low evidence for depression. Sex was found not to be a prognostic factor for CRPS or persistent pain. Conclusions: The associations between prognostic factors and persistent pain following a DRF are unclear. The small number of factors investigated in more than one study, along with poor reporting and methodological limitations contributed to an assessment of low to very low strength of evidence. Further prospective studies, investigating psychosocial factors as candidate predictors of multidimensional pain outcomes are recommended.

The effect of hyper-pronated foot on postural control and ankle muscle activity during running and cutting movement / El efecto del pie hiperpronado sobre el control postural y la actividad de los músculos del tobillo durante el movimiento de carrera y cambio de dirección / O efeito do pé hiper-pronado no controlo postural e actividade muscular no tornozelo durante a corrida e movimentos cortantes

Objective: The aim of this study was to examine the effect of hyper pronated foot on postural control and ankle muscle activity during running and cutting movement (v-cut).Methods: In this Cross-Sectional study, 42 young physically active (exercising three times per week regularly) males participated in this study, including 21 with hyper-pronated feet and 21 with normal feet. Each participant completed a running and cutting task. Body postural control was measured using a force platform (1000Hz) which was synchronized with surface electromyography of selected ankle muscles. MATLAB software was used to process and analyze the data. One-away ANOVA was used to identify any differences between groups.Results: Differing muscle activation patterns in the surrounding ankle musculature (tibialis anterior, peroneus longus) through to reduced postural stability in the medial-lateral direction and increased vertical ground reaction forces were observed between groups.Conclusion: According to the obtained results it seems that subtalar hyper-pronation can be regarded as a factor affecting the biomechanics of cutting by changing activation patterns of the muscles surrounding the ankle, and reducing postural control of the body in medial-lateral direction, but not in anterior-posterior direction. (AU)

Objetivo: El objetivo de este estudio fue examinar el efecto del pie hiperpronado sobre el control postural y la actividad de los músculos del tobillo durante el movimiento de carrera y cambio de dirección.Métodos: En este estudio transversal, participaron 42 hombres jóvenes físicamente activos (ejercitándose tres veces por semana con regularidad), incluidos 21 con pies hiperpronados y 21 con pies normales. Cada participante completó una tarea de correr y cambiar de dirección. El control de la postura corporal se midió utilizando una plataforma de fuerza (1000 Hz) que se sincronizó con la electromiografía de superficie de los músculos seleccionados del tobillo. Se utilizó el software MATLAB para procesar y analizar los datos. Se utilizó un ANOVA de una distancia para identificar las diferencias entre los grupos.Resultados: Se observaron diferentes patrones de activación muscular en la musculatura del tobillo (tibial anterior, peroneo largo) con estabilidad postural reducida en la dirección medial-lateral y un aumento de las fuerzas de reacción vertical del suelo entre los grupos.Conclusión: De acuerdo con los resultados obtenidos, parece que la hiperpronación puede ser considerada como un factor que afecta la biomecánica del cambio de dirección al modificar los patrones de activación de los músculos que del tobillo y reducir el control postural del cuerpo en dirección medial-lateral, pero no en dirección anteroposterior. (AU)

Objetivo: O objetivo deste estudo é examinar o efeito do pé hiper-pronado no controlo postural e actividade muscular no tornozelo durante a corrida e movimentos cortantes.Métodos: Neste estudo seccionado, 42 rapazes fisicamente ativos (exercitam regularmente 3 vezes por semana) participaram neste estudo, incluindo 21 com pé hyper-pronated. Cada participante completou um desafio de corrida e corte. A postural corporal foi medida usando uma plataforma com potência de 1000Hz, cujo fora sincronizada com uma eletromiografia superficial do músculos do tornozelo seleccionados. O software MATLAB foi utilizado para processar e analisar os dados. ANOVA foi utilizado para identificar quaisquer diferenciações entre grupos.Resultados: Padrões divergentes de ativação por volta do músculo do tornozelo (tibialis anterior peroneus longus) pela redução de estabilidade postural na direção medial-lateral e foi observado um aumento de reacções verticais térreas entre grupos.Conclusão: De acordo com os resultados obtidos, parece que a hyper-pronation pode ser observada como um factor que afecta os biomecânica de corte através da mudança e ativação dos padrões dos músculos à volta do tornozelo, reduzindo assim o controlo do corpo na direção médio-lateral mas não na direção anterior-posterior. (AU)

Ten-Year Results of the Triathlon Knee Replacement: A Cohort Study.

Introduction Studies evaluating the outcomes of different brands of knee prostheses are important to monitor patient outcomes and generate evidence to aid decisions around the choice of implant. The Triathlon® prosthesis (Stryker, Limerick, Ireland), one of the most commonly used total condylar knee prosthesis, is designed to provide greater knee motion and the potential for longer implant survivorship. The aim of this cohort study was to evaluate outcomes and survivorship of the Triathlon total knee replacement (TKR) up to 10 years post-operative. Methods Two-hundred sixty-six (266) patients listed for a Triathlon TKR in one orthopaedic hospital were recruited. Assessments were conducted preoperatively and then at three months and one, two, three, five, seven, and 10 years after surgery. Outcomes assessed included pain, function, knee-related quality of life (QoL), satisfaction, kneeling ability, activity levels, American Knee Society Score, complications, and survivorship. Results Large improvements in patient-reported outcomes were observed in the first three months after surgery, followed by small improvement up to one year post-operative, and then outcomes plateaued up to 10 years post-operative. Satisfaction with overall outcome ranged from 79%-94% over the duration of follow-up. Activity levels and kneeling ability were similar before and after surgery. There was a large improvement in the median American Knee Society score in the first three months post-operative, followed by a small but gradual improvement to 10 years post-operative. Survivorship was 95.4% (95% confidence interval 91.8-97.5%) at 10 years post-operative. Conclusions This study found that the Triathlon TKR results in excellent outcomes and survivorship to 10 years post-operative.

A cortical immune network map identifies distinct microglial transcriptional programs associated with ß-amyloid and Tau pathologies.

Microglial dysfunction has been proposed as one of the many cellular mechanisms that can contribute to the development of Alzheimer's disease (AD). Here, using a transcriptional network map of the human frontal cortex, we identify five modules of co-expressed genes related to microglia and assess their role in the neuropathologic features of AD in 540 subjects from two cohort studies of brain aging. Two of these transcriptional programs-modules 113 and 114-relate to the accumulation of ß-amyloid, while module 5 relates to tau pathology. We replicate these associations in brain epigenomic data and in two independent datasets. In terms of tau, we propose that module 5, a marker of activated microglia, may lead to tau accumulation and subsequent cognitive decline. We validate our model further by showing that three representative module 5 genes (ACADVL, TRABD, and VASP) encode proteins that are upregulated in activated microglia in AD.

Single cell RNA sequencing of human microglia uncovers a subset associated with Alzheimer's disease.

The extent of microglial heterogeneity in humans remains a central yet poorly explored question in light of the development of therapies targeting this cell type. Here, we investigate the population structure of live microglia purified from human cerebral cortex samples obtained at autopsy and during neurosurgical procedures. Using single cell RNA sequencing, we find that some subsets are enriched for disease-related genes and RNA signatures. We confirm the presence of four of these microglial subpopulations histologically and illustrate the utility of our data by characterizing further microglial cluster 7, enriched for genes depleted in the cortex of individuals with Alzheimer's disease (AD). Histologically, these cluster 7 microglia are reduced in frequency in AD tissue, and we validate this observation in an independent set of single nucleus data. Thus, our live human microglia identify a range of subtypes, and we prioritize one of these as being altered in AD.