A light-inducible protein clustering system for in vivo analysis of α-synuclein aggregation in Parkinson disease.

Neurodegenerative disorders refer to a group of diseases commonly associated with abnormal protein accumulation and aggregation in the central nervous system. However, the exact role of protein aggregation in the pathophysiology of these disorders remains unclear. This gap in knowledge is due to the lack of experimental models that allow for the spatiotemporal control of protein aggregation, and the investigation of early dynamic events associated with inclusion formation. Here, we report on the development of a light-inducible protein aggregation (LIPA) system that enables spatiotemporal control of α-synuclein (α-syn) aggregation into insoluble deposits called Lewy bodies (LBs), the pathological hallmark of Parkinson disease (PD) and other proteinopathies. We demonstrate that LIPA-α-syn inclusions mimic key biochemical, biophysical, and ultrastructural features of authentic LBs observed in PD-diseased brains. In vivo, LIPA-α-syn aggregates compromise nigrostriatal transmission, induce neurodegeneration and PD-like motor impairments. Collectively, our findings provide a new tool for the generation, visualization, and dissection of the role of α-syn aggregation in PD.

Hedgehog signaling regulates Wolffian duct development through the primary cilium†.

Primary cilia play pivotal roles in embryonic patterning and organogenesis through transduction of the Hedgehog signaling pathway (Hh). Although mutations in Hh morphogens impair the development of the gonads and trigger male infertility, the contribution of Hh and primary cilia in the development of male reproductive ductules, including the epididymis, remains unknown. From a Pax2Cre; IFT88fl/fl knock-out mouse model, we found that primary cilia deletion is associated with imbalanced Hh signaling and morphometric changes in the Wolffian duct (WD), the embryonic precursor of the epididymis. Similar effects were observed following pharmacological blockade of primary cilia formation and Hh modulation on WD organotypic cultures. The expression of genes involved in extracellular matrix, mesenchymal-epithelial transition, canonical Hh and WD development was significantly altered after treatments. Altogether, we identified the primary cilia-dependent Hh signaling as a master regulator of genes involved in WD development. This provides new insights regarding the etiology of sexual differentiation and male infertility issues.

3-aminohydantoin derivate as a promising scaffold in dopaminergic neuroprotection and neurorescue in the in vivo and in vitro 6-hydroxydopamine models of Parkinson's disease.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by a progressive loss of dopaminergic neurons in the substantia nigra, for which no disease-modifying treatments are available yet. Thus, developing new neuroprotective drugs with the potential to delay or stop the natural course of the disease is necessary. The aim of the present study was to evaluate the neuroprotective effects of a newly synthesized 3-aminohydantoin derivative named 3-amino-5-benzylimidazolidine-2,4-dione (PHAH). The possible neuroprotective and neurorescue effects of the synthesized compound were tested: (i) in N27 dopaminergic and BV-2 microglial cell lines treated with 6-hydroxydopamine (6-OHDA) and (ii) in the 6-OHDA rat model of PD. PHAH administration reduced proinflammatory markers, including nitric oxide synthase and interleukin-1ß, in BV-2 cells activated by lipopolysaccharide. Although PHAH did not restore cell death induced by 6-OHDA, it was not cytotoxic for dopaminergic cells since cell viability, under the effect of the two concentrations, remained comparable to that of the control cells. Most interestingly, PHAH restored 6-OHDA-induced dopaminergic neurodegeneration in the substantia nigra and striatum and ameliorated 6-OHDA-induced oxidative stress in the rat brain. In summary, we have proven that in PD models, PHAH has neuroprotective effects in vivo and anti-inflammatory effects in vitro; however, these effects remain to be confirmed by carrying out certain specific behavioural tests as well as by exploring other neuroinflammatory markers. The present work also suggests that PHAH is a promising scaffold that can serve as the basis for the design and synthesis of other derivatives that can be potent antiparkinsonian agents.

Hedgehog signaling pathway regulates gene expression profile of epididymal principal cells through the primary cilium.

Primary cilia (PC) are organelles that sense and respond to dynamic changes of the extracellular milieu through the regulation of target genes. By using the epididymis as a model system, we determined the contribution of primary cilia in the regulation of epithelial cell functions through the transduction of the Hedgehog (Hh) signaling pathway. Both Sonic (SHH) and Indian Hedgehog (IHH) ligands were detected in epididymal epithelial cells by confocal microscopy and found secreted in the extracellular space. Gene expression profiling preformed on ciliated epithelial cells indicated that 153 and 1052 genes were differentially expressed following treatment with the Hh agonist SAG or the Hh antagonist cyclopamine (Cyclo), respectively. Strikingly, gene ontology analysis indicated that genes associated with immune response were the most affected following Hh modulation. The contribution of epididymal PC to canonical Hh pathway transduction was validated by ciliobrevin D treatment, which induced a significant decrease in PC length and a reduction in the expression Hh signaling targets. Such findings bring us closer to a molecular understanding of the subtle immune balance observed in some epithelia, including the epididymis and the intestine, which are organs featuring both tolerance toward autoimmune spermatozoa (or commensal bacteria) and defense against pathogens.

Histomorphometric analyses of human adipose tissues using intact, flash-frozen samples.

Histomorphometric analyses of adipose tissue usually require formalin fixation of fresh samples. Our objective was to determine if intact, flash-frozen whole adipose tissue samples stored at - 80 °C could be used for measurements developed for fresh-fixed adipose tissues. Portions of adipose tissue samples were either formalin-fixed immediately upon sampling or flash-frozen and stored at - 80 °C and then formalin-fixed during the thawing process. Mean adipocyte diameter was measured. Immunohistochemistry was performed on additional samples to identify macrophage subtypes (M1, CD14 + and M2, CD206 +) and total (CD68 +) number. All slides were counterstained using haematoxylin and eosin (H&E). Visual inspection of H&E-stained adipose tissue slides performed in a blinded fashion showed little or no sign of cell breakage in 74% of frozen-fixed samples and in 68% of fresh-fixed samples (p > 0.5). There was no difference in the distribution frequencies of adipocyte sizes in fresh-fixed vs. frozen-fixed tissues in both depots (p > 0.9). Mean adipocyte size from frozen-fixed samples correlated significantly and positively with adipocyte size from fresh-fixed samples (r = 0.74, p < 0.0001, for both depots). The quality of staining/immunostaining and appearance of tissue architecture were comparable in fresh-fixed vs. frozen-fixed samples. In conclusion, intact flash-frozen adipose tissue samples stored at - 80 °C can be used to perform techniques conventionally applied to fresh-fixed samples. This approach allows for retrospective studies with frozen human adipose tissue samples.

Cell-lineage specificity of primary cilia during postnatal epididymal development.

STUDY QUESTION: Where are primary cilia (PC) organelles located during postnatal epididymal development? SUMMARY ANSWER: Our findings unveil the existence of PC sensory organelles in different epididymal cell types according to postnatal development stage. WHAT IS KNOWN ALREADY: Primary cilia are sensory organelles that orchestrate major signaling pathways during organ development and homeostasis. Epididymal PC have been detected in the horses, donkey and mules but their cell-lineage specificity has never been investigated in this organ. STUDY DESIGN, SIZE, DURATION: A longitudinal study was performed by examining tissue from n = 3 to n = 10 transgenic mice at different times of postnatal development. Tissues were fixed by intracardiac perfusion and the epididymides collected. PARTICIPANTS/MATERIALS, SETTING, METHODS: Transmission electron microscopy and confocal microscopy/3D reconstruction were used on a double transgenic mouse model expressing endogenous fluorescence in PC and centrioles (Arl13b-mCherry/Centrin2-GFP). Several PC parameters (i.e. length, orientation relative to the lumen) were quantified by using an image-processing pipeline. Epididymal tissues and serum-free cultures of DC2 immortalized epididymal principal murine cell lines were used to identify primary ciliary signaling components. MAIN RESULTS AND THE ROLE OF CHANCE: We report here a constitutive localization of PC in peritubular myoid cells and a dynamic profiling in epithelial cells throughout postnatal epididymal development. While PC are present at the apical pole of the undifferentiated epithelial cells from birth to puberty, they are absent from the apical pole of the epithelium in adults, where they appear exclusively associated with cytokeratin 5-positive basal cells. We determined that PC from epididymal cells are associated with polycystin 1 (PC1), polycystin 2 (PC2), and Gli-3 Hedgehog signaling transcription factor. No inter-individual variability was observed within each age group. LIMITATIONS, REASONS FOR CAUTION: As our present study is descriptive and performed exclusively in the mouse, future functional studies will be required to unravel the contribution of these organelles in the control of reproductive functions. WIDER IMPLICATIONS OF THE FINDINGS: Acknowledging the important roles played by PC sensory organelles in organ homeostasis and development in humans, our work opens new avenues of research concerning the cellular control of epididymal functions, which are essential to male fertility. STUDY FUNDING/COMPETING INTEREST(S): Study funded by an NSERC operating grant to CB (RGPIN-2015-109194). No competing interest to declare.

Platelet microparticles are internalized in neutrophils via the concerted activity of 12-lipoxygenase and secreted phospholipase A2-IIA.

Platelets are anucleated blood elements highly potent at generating extracellular vesicles (EVs) called microparticles (MPs). Whereas EVs are accepted as an important means of intercellular communication, the mechanisms underlying platelet MP internalization in recipient cells are poorly understood. Our lipidomic analyses identified 12(S)-hydroxyeicosatetranoic acid [12(S)-HETE] as the predominant eicosanoid generated by MPs. Mechanistically, 12(S)-HETE is produced through the concerted activity of secreted phospholipase A2 IIA (sPLA2-IIA), present in inflammatory fluids, and platelet-type 12-lipoxygenase (12-LO), expressed by platelet MPs. Platelet MPs convey an elaborate set of transcription factors and nucleic acids, and contain mitochondria. We observed that MPs and their cargo are internalized by activated neutrophils in the endomembrane system via 12(S)-HETE. Platelet MPs are found inside neutrophils isolated from the joints of arthritic patients, and are found in neutrophils only in the presence of sPLA2-IIA and 12-LO in an in vivo model of autoimmune inflammatory arthritis. Using a combination of genetically modified mice, we show that the coordinated action of sPLA2-IIA and 12-LO promotes inflammatory arthritis. These findings identify 12(S)-HETE as a trigger of platelet MP internalization by neutrophils, a mechanism highly relevant to inflammatory processes. Because sPLA2-IIA is induced during inflammation, and 12-LO expression is restricted mainly to platelets, these observations demonstrate that platelet MPs promote their internalization in recipient cells through highly regulated mechanisms.

Platelets release mitochondria serving as substrate for bactericidal group IIA-secreted phospholipase A2 to promote inflammation.

Mitochondrial DNA (mtDNA) is a highly potent inflammatory trigger and is reportedly found outside the cells in blood in various pathologies. Platelets are abundant in blood where they promote hemostasis. Although lacking a nucleus, platelets contain functional mitochondria. On activation, platelets produce extracellular vesicles known as microparticles. We hypothesized that activated platelets could also release their mitochondria. We show that activated platelets release respiratory-competent mitochondria, both within membrane-encapsulated microparticles and as free organelles. Extracellular mitochondria are found in platelet concentrates used for transfusion and are present at higher levels in those that induced acute reactions (febrile nonhemolytic reactions, skin manifestations, and cardiovascular events) in transfused patients. We establish that the mitochondrion is an endogenous substrate of secreted phospholipase A2 IIA (sPLA2-IIA), a phospholipase otherwise specific for bacteria, likely reflecting the ancestral proteobacteria origin of mitochondria. The hydrolysis of the mitochondrial membrane by sPLA2-IIA yields inflammatory mediators (ie, lysophospholipids, fatty acids, and mtDNA) that promote leukocyte activation. Two-photon microscopy in live transfused animals revealed that extracellular mitochondria interact with neutrophils in vivo, triggering neutrophil adhesion to the endothelial wall. Our findings identify extracellular mitochondria, produced by platelets, at the midpoint of a potent mechanism leading to inflammatory responses.

Automated High-Performance Analysis of Lung Morphometry.

Automation of lung morphometric analysis is an asset in the study of lung pathophysiology because it is an assurance of robustness, reproducibility, and rapidity. The novel automated morphometric approach presented here meets these criteria. This new method collects multiple parameters, allowing quantitative elucidation of the pathophysiology of the developing and mature lungs. The automated morphometric analysis is reliable and allows the analysis of a greater proportion of each lung together with a higher number of samples and superior reproducibility than manual analysis. The use of this method revealed that treatment with 80% oxygen and lung development presented an opposite effect on most of the analyzed parameters. In conclusion, this novel approach allowed the collection of new fundamental morphometric data on lung development and a deeper comprehension of the effect of hyperoxia.

GPER1-mediated immunomodulation and neuroprotection in the myenteric plexus of a mouse model of Parkinson's disease.

Lewy pathology affects the gastrointestinal tract in Parkinson's disease (PD) and recent reports suggest a link between the disorder and gut inflammation. In this study, we investigated enteric neuroprotection and macrophage immunomodulation by 17ß-estradiol (E2) and the G protein-coupled estrogen receptor 1 (GPER1) in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse PD model. We found that both E2 and the GPER1 agonist G1 are protective against the loss of dopamine myenteric neurons and inhibited enteric macrophage infiltration in MPTP-treated mice. Coadministration of GPER1 antagonist G15, while completely blocking the neuroprotective and anti-inflammatory effects of G1 also partially prevented those of E2. Interestingly, we found that E2 and G1 treatments could directly alter MPTP-mediated immune responses independently from neurodegenerative processes. Analyses of monocyte/macrophage NF-κB and iNOS activation and FACs immunophenotype indicated that 1-methyl-4-phenylpyridinium (MPP(+)) treatment induces a strong immune response in monocytes, comparable to that of canonical challenge by lipopolysaccharide. In these cells, G1 and E2 treatment are equally potent in promoting a shift toward an anti-inflammatory "M2" immunophenotype reducing MPP(+)-induced NF-κB and iNOS activation. Moreover, G15 also antagonized the immunomodulatory effects of G1 in MPP(+)-treated macrophages. Together these data provide the first evidence for the role of GPER1 in enteric immunomodulation and neuroprotection. Considering increasing recognition for myenteric pathology as an early biomarker for PD, these findings provide a valuable contribution for better understanding and targeting of future therapeutic strategies.

Striatal allografts in patients with Huntington's disease: impact of diminished astrocytes and vascularization on graft viability.

Neuronal transplantation has been proposed as a potential therapy to replace lost neurons in Huntington's disease. Transplant vascularization and trophic support are important for graft survival. However, very few studies have specifically addressed graft vascularization in patients with neurological disorders. In the present study, we analysed the vasculature of the host putamen and solid grafts of foetal striatal tissue transplanted into patients with Huntington's disease 9 and 12 years previously. Grafts were characterized by a significantly reduced number of large calibre blood vessels in comparison with the host brain. There were also significantly fewer astrocytes and gap junctions, suggesting a lack of functional blood-brain barrier components within the grafted tissue. Additionally, grafts demonstrated a nearly complete absence of pericytes (compared with the striatum) that are considered important for vascular stabilization and angiogenesis. Finally, the host striatum had a marked increase in atrophic astrocytes in comparison with controls and grafts. The extent to which the lower number of large calibre vessels and astrocytes within the transplants contributed to suboptimal graft survival is unknown. The marked increase in atrophic astrocytes in the host brain surrounding the grafts suggests that reduced host trophic support may also contribute to poor graft survival in Huntington's disease. A better understanding of the way in which these components support allografted tissue is critical to the future development of cell-based therapies for the treatment of Huntington's disease.

Ovine model of congenital chest wall and spine deformity: From birth to 3 months follow-up.

Background: The evolution and treatment of lung alterations related to congenital spine and chest wall deformities (CWD) are poorly understood. Most animal models of CWD created postnatally were not evaluated for respiratory function. The goal of our study was to evaluate the effects of a CWD induced in utero on lung growth and function in an ovine model. Methods: A CWD was induced in utero at 70-75 days of gestation in 14 ovine fetuses by resection of the 7th and 8th left ribs. Each non-operated twin fetus was taken as control. Respiratory mechanics was studied postnatally in the first week and at 1, 2, and 3 months. Post-mortem respiratory mechanics and lung histomorphometry were also assessed at 3 months. Results: Eight out of 14 CWD lambs (57%) and 14 control lambs survived the postnatal period. One severe and five mild deformities were induced. At birth, inspiratory capacity (25 vs. 32 mL/kg in controls), and dynamic (1.4 vs. 1.8 mL/cmH2O/kg), and static (2.0 vs. 2.5 mL/cmH2O/kg) respiratory system compliances were decreased in CWD lambs. Apart from a slight decrease in inspiratory capacity at 1 month of life, no other differences were observed in respiratory mechanics measured in vivo thereafter. Postmortem measurements found a significant decrease in lung compliance-for each lung and for both lungs taken together-in CWD lambs. No differences in lung histology were detected at 3 months in CWD animals compared to controls. Conclusions: Our study is the first to assess the effects of a prenatally induced CWD on lung development and function from birth to 3 months in an ovine model. Our results show no significant differences in lung histomorphometry at 3 months in CWD lambs compared to controls. Resolution at 1 month of the alterations in respiratory mechanics present at birth may be related to the challenge in inducing severe deformities.

Sex differences in kidney metabolism may reflect sex-dependent outcomes in human diabetic kidney disease.

Diabetic kidney disease (DKD) is the main cause of chronic kidney disease (CKD) and progresses faster in males than in females. We identify sex-based differences in kidney metabolism and in the blood metabolome of male and female individuals with diabetes. Primary human proximal tubular epithelial cells (PTECs) from healthy males displayed increased mitochondrial respiration, oxidative stress, apoptosis, and greater injury when exposed to high glucose compared with PTECs from healthy females. Male human PTECs showed increased glucose and glutamine fluxes to the TCA cycle, whereas female human PTECs showed increased pyruvate content. The male human PTEC phenotype was enhanced by dihydrotestosterone and mediated by the transcription factor HNF4A and histone demethylase KDM6A. In mice where sex chromosomes either matched or did not match gonadal sex, male gonadal sex contributed to the kidney metabolism differences between males and females. A blood metabolomics analysis in a cohort of adolescents with or without diabetes showed increased TCA cycle metabolites in males. In a second cohort of adults with diabetes, females without DKD had higher serum pyruvate concentrations than did males with or without DKD. Serum pyruvate concentrations positively correlated with the estimated glomerular filtration rate, a measure of kidney function, and negatively correlated with all-cause mortality in this cohort. In a third cohort of adults with CKD, male sex and diabetes were associated with increased plasma TCA cycle metabolites, which correlated with all-cause mortality. These findings suggest that differences in male and female kidney metabolism may contribute to sex-dependent outcomes in DKD.

Impact of sex on neuroimmune contributions to Parkinson's disease.

Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease. Inflammation has been observed in both the idiopathic and familial forms of PD. Importantly, PD is reported more often in men than in women, men having at least 1.5- fold higher risk to develop PD than women. This review summarizes the impact of biological sex and sex hormones on the neuroimmune contributions to PD and its investigation in animal models of PD. Innate and peripheral immune systems participate in the brain neuroinflammation of PD patients and is reproduced in neurotoxin, genetic and α-synuclein based models of PD. Microglia and astrocytes are the main cells of the innate immune system in the central nervous system and are the first to react to restore homeostasis in the brain. Analysis of serum immunoprofiles in female and male control and PD patients show that a great proportion of these markers differ between males and females. The relationship between cerebrospinal fluid inflammatory markers and PD clinical characteristics or PD biomarkers shows sex differences. Conversely, in animal models of PD, sex differences in inflammation are well documented and the beneficial effects of endogenous and exogenous estrogenic modulation in inflammation have been reported. Targeting neuroinflammation in PD is an emerging therapeutic option but gonadal drugs have not yet been investigated in this respect, thus offering new opportunities for sex specific treatments.

Three-Dimensional Analysis of Sex- and Gonadal Status- Dependent Microglial Activation in a Mouse Model of Parkinson's Disease.

Parkinson's disease (PD) is characterized by neurodegeneration and neuroinflammation. PD prevalence and incidence are higher in men than in women and modulation of gonadal hormones could have an impact on the disease course. This was investigated in male and female gonadectomized (GDX) and SHAM operated (SHAM) mice. Dutasteride (DUT), a 5α-reductase inhibitor, was administered to these mice for 10 days to modulate their gonadal sex hormones. On the fifth day of DUT treatment, mice received 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to model PD. We have previously shown in these mice the toxic effect of MPTP in SHAM and GDX males and in GDX females on dopamine markers and astrogliosis whereas SHAM females were protected by their female sex hormones. In SHAM males, DUT protected against MPTP toxicity. In the present study, microglial density and the number of doublets, representative of a microglial proliferation, were increased by the MPTP lesion only in male mice and prevented by DUT in SHAM males. A three-dimensional morphological microglial analysis showed that MPTP changed microglial morphology from quiescent to activated only in male mice and was not prevented by DUT. In conclusion, microgliosis can be modulated by sex hormone-dependent and independent factors in a mice model of PD.

Sex and Age Differences in a Progressive Synucleinopathy Mouse Model.

The mutation and overexpression of the alpha-synuclein protein (αSyn), described as synucleinopathy, is associated with Parkinson's disease (PD)-like pathologies. A higher prevalence of PD is documented for men versus women, suggesting female hormones' implication in slowing PD progression. The nigrostriatal dopamine (DA) neurons in rodent males are more vulnerable to toxins than those in females. The effect of biological sex on synucleinopathy remains poorly described and was investigated using mice knocked out for murine αSyn (SNCA-/-) and also overexpressing human αSyn (SNCA-OVX) compared to wildtype (WT) mice. All the mice showed decreased locomotor activity with age, and more abruptly in the male than in the female SNCA-OVX mice; anxiety-like behavior increased with age. The SNCA-OVX mice had an age-dependent accumulation of αSyn. Older age was associated with the loss of nigral DA neurons and decreased striatal DA contents. The astrogliosis, microgliosis, and cytokine concentrations increased with aging. More abrupt nigrostriatal DA decreases and increased microgliosis were observed in the male SNCA-OVX mice. Human αSyn overexpression and murine αSyn knockout resulted in behavioral dysfunctions, while only human αSyn overexpression was toxic to DA neurons. At 18 months, neuroprotection was lost in the female SNCA-OVX mice, with a likely loss of estrus cycles. In conclusion, sex-dependent αSyn toxicity was observed, affecting the male mice more significantly.

Functional recovery after peripheral nerve injury is dependent on the pro-inflammatory cytokines IL-1ß and TNF: implications for neuropathic pain.

IL-1ß and TNF are potential targets in the management of neuropathic pain after injury. However, the importance of the IL-1 and TNF systems for peripheral nerve regeneration and the mechanisms by which these cytokines mediate effects are to be fully elucidated. Here, we demonstrate that mRNA and protein levels of IL-1ß and TNF are rapidly upregulated in the injured mouse sciatic nerve. Mice lacking both IL-1ß and TNF, or both IL-1 type 1 receptor (IL-1R1) and TNF type 1 receptor (TNFR1), showed reduced nociceptive sensitivity (mechanical allodynia) compared with wild-type littermates after injury. Microinjecting recombinant IL-1ß or TNF at the site of sciatic nerve injury in IL-1ß- and TNF-knock-out mice restored mechanical pain thresholds back to levels observed in injured wild-type mice. Importantly, recovery of sciatic nerve function was impaired in IL-1ß-, TNF-, and IL-1ß/TNF-knock-out mice. Notably, the infiltration of neutrophils was almost completely prevented in the sciatic nerve distal stump of mice lacking both IL-1R1 and TNFR1. Systemic treatment of mice with an anti-Ly6G antibody to deplete neutrophils, cells that play an essential role in the genesis of neuropathic pain, did not affect recovery of neurological function and peripheral axon regeneration. Together, these results suggest that targeting specific IL-1ß/TNF-dependent responses, such as neutrophil infiltration, is a better therapeutic strategy for treatment of neuropathic pain after peripheral nerve injury than complete blockage of cytokine production.

Neuronal degeneration in striatal transplants and Huntington's disease: potential mechanisms and clinical implications.

Cell therapy offers the possibility of replacing degenerated neurons thereby improving the symptoms of neurodegenerative disorders such as Huntington's disease. However, clinical benefits in patients with Huntington's disease, if any, have been transient and modest. Grafts survived well at 18 months in one patient with Huntington's disease, but graft survival was markedly attenuated by 10 years in three other patients from this transplantation cohort. It is critical to delineate the causes of graft degeneration if such therapies will be utilized in patients with a goal of achieving meaningful clinical benefit. Similar challenges may also accrue to future stem cell therapies. Here we discuss the potential causes of suboptimal long-term graft survival in patients with Huntington's disease, including allograft immunoreactivity, microglial responses targeted to grafted cells and cell-to-cell neurotoxicity. We also discuss similar challenges and unique differences comparing neuronal grafts in patients with Parkinson's and Huntington's diseases.

Live imaging of platelets and neutrophils during antibody-mediated neurovascular thrombosis.

Immune complexes form in systemic disorders such as rheumatological, autoimmune, and allergic diseases or in response to infections or medications. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) adenoviral vector vaccines have been associated with rare yet serious thrombotic complications in the brain due to the formation of immune complexes that activate platelets. There are currently no data visualizing the interplay of platelets with leukocytes and the brain vasculature endothelium in response to immune complexes. This is in part due to the absence of FcγRIIA in mice, a receptor for immune complexes implicated in these thrombotic incidents. Here, we describe and illustrate events at the cellular level that take place in the brain vasculature in response to systemic administration of surrogate immune complexes. We used Ly6gCre+/-::Rosa26-TdT+/-::CD41-YFP+/- mice expressing the FcγRIIA transgene and fluorescence in neutrophils and platelets. Using real-time videomicroscopy to capture high-velocity events in conjunction with unbiased computer-assisted analyses, we provide images and quantifications of the cellular responses downstream of FcγRIIA stimulation. We observed transient and stable platelet-neutrophil interactions, platelets forming thrombi, and neutrophil adhesion to blood vessel walls. This imaging approach in a quadruple transgenic animal model can be used for the study of the pathogenic roles of immune complexes in disease.

Differential contribution of estrogen receptors to the intestinal therapeutic effects of 17ß-estradiol in a murine model of Parkinson's disease.

Beneficial effects of estrogens have been reported in Parkinson's disease (PD) for many years. We previously reported their neuroprotective and anti-inflammatory potentials in the enteric nervous system of the intestine, a region possibly affected during the early stages of the disease according to Braak's hypothesis. Three different estrogen receptors have been characterized to date: the estrogen receptor alpha (ERα), the estrogen receptor beta (ERß) and the G protein coupled estrogen receptor 1 (GPER1). The aim of the present study was to decipher the individual contribution of each estrogen receptor to the therapeutic properties of 17ß-estradiol (E2) in the myenteric plexus of the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. Different agonists, 4,4',4''-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT; ERα), 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN; ERß), G1 (GPER1), and antagonists, ICI 182,780 (ERα and ERß), G15 (GPER1), were used to analyze the involvement of each receptor. We confirmed that G1 protects dopamine (DA) neurons to a similar extent as E2. An anti-inflammatory effect on proinflammatory macrophages and cultured human monocytes was also demonstrated with E2 and G1. The effects of PPT and DPN were less potent than G1 with only a partial neuroprotection of DA neurons by PPT and a partial reduction of interleukin (IL)- 1ß production in monocytes by PPT and DPN. Overall, the present results indicate that the positive outcomes of estrogens are mainly through activation of GPER1. Therefore, this suggests that targeting GPER1 could be a promising approach for future estrogen-based hormone therapies during early PD.