[show abstract][hide abstract] ABSTRACT: The recent demonstration of the presence of Lewy pathology in the submandibular glands of Parkinson's disease (PD) patients prompted us to evaluate the diagnostic performance of minor salivary gland biopsy for PD. Minor salivary glands were examined for Lewy pathology using phosphorylated alpha-synuclein antibody in 16 patients with clinically diagnosed PD and 11 control subjects with other neurological disorders. Abnormal accumulation of alpha-synuclein was found in 3 out of 16 PD patients. Two control subjects exhibited weak phosphorylated alpha-synuclein immunoreactivity. Our results do not support the use of minor salivary glands biopsy for the detection of Lewy pathology in living subjects.
[show abstract][hide abstract] ABSTRACT: Dementia with Lewy bodies (DLB) is the second cause of degenerative dementia in autopsy studies. In clinical pratice however, the prevalence of DLB is much lower with important intercenter variations. Among the reasons for this low sensitivity of DLB diagnosis are (1) the imprecision and subjectivity of the diagnostic criteria; (2) the underestimation of non-motor symptoms (REM-sleep behavior disorder, dysautonomia, anosmia); mostly (3) the nearly constant association of Lewy bodies with Alzheimer's disease pathology, which dominates the clinical phenotype. With the avenue of targeted therapies against the protein agregates, new clinical scales able to apprehend the coexistence of Lewy pathology in Alzheimer's disease are expected.
[show abstract][hide abstract] ABSTRACT: The monolayer of columnar epithelial cells lining the gastrointestinal tract-the intestinal epithelial barrier (IEB)-is the largest exchange surface between the body and the external environment. The permeability of the IEB has a central role in the regulation of fluid and nutrient intake as well as in the control of the passage of pathogens. The functions of the IEB are highly regulated by luminal as well as internal components, such as bacteria or immune cells, respectively. Evidence indicates that two cell types of the enteric nervous system (ENS), namely enteric neurons and enteric glial cells, are potent modulators of IEB functions, giving rise to the novel concept of a digestive 'neuronal-glial-epithelial unit' akin to the neuronal-glial-endothelial unit in the brain. In this Review, we summarize findings demonstrating that the ENS is a key regulator of IEB function and is actively involved in pathologies associated with altered barrier function.
[show abstract][hide abstract] ABSTRACT: Lewy pathology affects the gastrointestinal tract in Parkinson's disease (PD) and data from recent genetic studies suggest a link between PD and gut inflammation. We therefore undertook the present survey to investigate whether gastrointestinal inflammation occurs in PD patients. Nineteen PD patients and 14 age-matched healthy controls were included. For each PD patients, neurological and gastrointestinal symptoms were assessed using the Unified Parkinson's Disease Rating Scale part III and the Rome III questionnaire, respectively and cumulative lifetime dose of L-dopa was calculated. Four biopsies were taken from the ascending colon during the course of a total colonoscopy in controls and PD patients. The mRNA expression levels of pro-inflammatory cytokines (tumor necrosis factor alpha, interferon gamma, interleukin-6 and interleukin-1 beta) and glial marker (Glial fibrillary acidic protein, Sox-10 and S100-beta) were analyzed using real-time PCR in two-pooled biopsies. Immunohistochemical analysis was performed on the two remaining biopsies using antibodies against phosphorylated alpha-synuclein to detect Lewy pathology. The mRNA expression levels of pro-inflammatory cytokines as well as of two glial markers (Glial fibrillary acidic protein and Sox-10) were significantly elevated in the ascending colon of PD patients with respect to controls. The levels of tumor necrosis factor alpha, interferon gamma, interleukin-6, interleukin-1 beta and Sox-10 were negatively correlated with disease duration. By contrast, no correlations were found between the levels of pro-inflammatory cytokines or glial markers and disease severity, gastrointestinal symptoms or cumulative lifetime dose of L-dopa. There was no significant difference in the expression of pro-inflammatory cytokines or glial marker between patients with and without enteric Lewy pathology. Our findings provide evidence that enteric inflammation occurs in PD and further reinforce the role of peripheral inflammation in the initiation and/or the progression of the disease.
Neurobiology of Disease 09/2012; · 5.62 Impact Factor
[show abstract][hide abstract] ABSTRACT: Routine colonic biopsies allow the detection of alpha-synuclein aggregates in the enteric nervous system (ENS) in living Parkinson's disease (PD) patients. Whether the ENS is affected by alpha-synuclein pathology in multiple system atrophy (MSA) has not been studied yet. The aim of the present research was therefore to analyze colonic biopsies in MSA for the presence of alpha-synuclein pathology. Six MSA and 9 PD patients were included. Four biopsies, taken from the descending colon during the course of a rectosigmoidscopy were microdissected, and analyzed by immunohistochemistry using antibodies against phosphorylated alpha-synuclein and neurofilaments NF 200 kDa. Aggregates of alpha-synuclein were detected in one out of 6 MSA patients and in 5 out of 9 PD patients. This demonstrates that, despite being less frequent than in PD, alpha-synuclein deposits can be observed in the ENS in MSA.
Parkinsonism & Related Disorders 05/2012; 18(7):893-5. · 3.27 Impact Factor
[show abstract][hide abstract] ABSTRACT: Increasing evidence suggests that enteric glial cells (EGCs) are critical for enteric neuron survival and functions. In particular, EGCs exert direct neuroprotective effects mediated in part by the release of glutathione. However, other glial factors such as those identified as regulating the intestinal epithelial barrier and in particular the omega-6 fatty acid derivative 15-deoxy-Δ¹²,¹⁴-prostaglandin J2 (15d-PGJ2) could also be involved in EGC-mediated neuroprotection. Therefore, our study aimed to assess the putative role of EGC-derived 15d-PGJ2 in their neuroprotective effects. We first showed that pretreatment of primary cultures of enteric nervous system(ENS)or humann euroblastoma cells (SH-SY5Y)with 15d-PGJ2 dose dependently prevented hydrogen peroxide neurotoxicity. Furthermore, neuroprotective effects of EGCs were significantly inhibited following genetic invalidation in EGCs of the key enzyme involved in 15d-PGJ2 synthesis, i.e. L-PGDS. We next showed that 15d-PGJ2 effects were mediated by an Nrf2 dependent pathway but were not blocked by PPARγ inhibitor (GW9662) in SH-SY5Y cells and enteric neurons. Finally, 15d-PGJ2 induced a significant increase in glutamate cysteine ligase expression and intracellular glutathione in SH cells and enteric neurons. In conclusion, we identified 15d-PGJ2 as a novel glial-derived molecule with neuroprotective effects in the ENS. This study further supports the concept that omega-6 derivatives such as 15d-PGJ2 might be used in preventive and/or therapeutic strategies for the treatment of enteric neuropathies.
The Journal of Physiology 04/2012; 590(Pt 11):2739-50. · 4.38 Impact Factor
[show abstract][hide abstract] ABSTRACT: No validated biomarker is yet available for Parkinson's disease (PD). Clinical PD symptoms include dopa-responsive motor symptoms and dopa-resistant non motor symptoms. Some of the non motor symptoms begin during the premotor stage, like constipation, hyposmia or REM-sleep disorders. Dementia, gait disorders and dysarthria occur in later stages of the disease. PD pathology extends well beyond the substantia nigra. It affects autonomic and non autonomic nuclei in the brainstem and in the medulla, the olfactory bulb and the peripheral autonomic nervous system. Alpha-synuclein aggregates, called Lewy bodies and Lewy neurites, are detectable in these structures at early stages. The study of the enteric nervous system (ENS) displays the Lewy pathology in living patients through the digestive biopsies. Minor salivary glands analysis could be a good marker as well, but this needs confirmation. An anatomopathologic PD biomarker would be interesting at different stages of PD: for the positive diagnosis, to follow the progression and to develop neuroprotective treatments.
La Presse Médicale 01/2012; 41(7-8):695-701. · 0.87 Impact Factor
[show abstract][hide abstract] ABSTRACT: Usually, levodopa-induced dyskinesia does not remain unchanged throughout the day in Parkinson's disease (PD) patients and varies according to the level of correction of PD symptomatology provided by the treatment. We observed two PD patients with unusual buccolingual masticatory movements which did not seem to fluctuate, either throughout the day during dopaminergic treatment or during a standardised levodopa challenge. After their dopaminergic treatment had been changed to a less pulsatile form of administration (ie, the use of dopamine agonist alone in the first patient and an increase in the dosage of dopamine agonist with a low dose of levodopa in the second), these abnormal movements totally disappeared in the first patient and were greatly improved in the second. These observations suggest that levodopa can have prolonged effects (several days) and induce prolonged buccolingual masticatory movements similar in type to those classically observed with dopamine receptor antagonists (neuroleptics).
[show abstract][hide abstract] ABSTRACT: The objective of this study was to examine the diagnostic accuracy of imaging and CSF biomarkers in clinically ambiguous dementia (CAD). 69 patients were prospectively followed. The endpoint was clinical diagnosis at follow-up of 24 months based upon existing criteria. Medial temporal lobe atrophy score on MRI, distinctive patterns on 99 mTc-HMPAO-SPECT, and CSF levels of amyloid-β peptide, total tau protein, and P-tau181P were used together with neuropsychological testing to assess Se (sensitivity) and Sp (specificity) of separate and combined markers. 60 patients reached the endpoint. A definite diagnosis was achieved in 48 patients. CSF biomarkers had a Sp of 71% and a Se of 100% for Alzheimer's disease (AD) diagnosis. Sp increased to 88% and 93% when MRI and MRI + SPECT were combined, at the expense of Se. CSF biomarkers levels also provided clues to frontotemporal (FTD) or vascular dementias (VaD) diagnosis when situated in an intermediate range between normal and pathological values. MRI and SPECT contributed mostly to the diagnosis of VaD (Se 88%, Sp 75%) and FTD (Se 73%, Sp 78%), respectively. Initial neuropsychological testing had a poor diagnostic accuracy, except for a neuropsychiatric inventory score >40 for the diagnosis of FTD (Se 73%, Sp 84%). Independent of the clinical diagnosis, medial temporal lobe atrophy and total-tau were best correlated with cognitive decline at 2 years. In conclusion, CSF biomarkers efficiently predict evolution toward an AD phenotype in CAD. Imaging biomarkers mostly contribute to the differential diagnosis between non-AD dementias. Initial neuropsychological testing was poorly contributive in CAD diagnosis.
[show abstract][hide abstract] ABSTRACT: Il n’existe pas, à l’heure actuelle, de biomarqueur validé de la maladie de Parkinson (MP).
Les signes cliniques de la MP comportent des signes moteurs sensibles à la lévodopa et des signes non moteurs dopa-résistants. Certains signes non moteurs apparaissent au stade prémoteur, comme la constipation, l’hyposmie ou les troubles du comportement en sommeil paradoxal. La démence et les signes axiaux (trouble de la statique, freezing, chutes et dysarthrie) apparaissent à un stade tardif.
L’atteinte pathologique n’est pas restreinte à la perte neuronale nigrostriée. Elle concerne aussi des noyaux autonomes et non autonomes du tronc cérébral et de la moelle épinière, le bulbe olfactif et le système nerveux autonome (SNA) périphérique. Des agrégats d’α-synucléine, appelés corps et neurites de Lewy, y sont précocement mis en évidence.
L’étude du système nerveux entérique (SNE) permet de mettre en évidence la pathologie de Lewy du vivant des patients parkinsoniens, par le biais des biopsies digestives. Sa mise en évidence au sein des glandes salivaires accessoires pourrait constituer un marqueur intéressant, mais les rares études concernées nécessitent confirmation.
Un biomarqueur anatomopathologique de la MP analysable à différents stades de la MP permettrait le diagnostic positif, le suivi de la progression de la maladie et contribuerait au développement et à la validation de traitements neuroprotecteurs.
[show abstract][hide abstract] ABSTRACT: We have shown that routine biopsies of the ascending colon obtained at colonoscopy allow the detection of Lewy neurites (LN) in the enteric nervous system (ENS) of Parkinson's disease (PD) patients. Although colonoscopy is a relatively safe procedure, it requires colon preparation and anesthesia. The present study was therefore undertaken to evaluate whether descending colon and rectal biopsies that are obtainable by rectosigmoidoscopy allow the detection of Lewy pathology in the ENS. A total of 9 controls and 26 PD patients were included and analyzed. Two biopsies were taken from the ascending, descending colon and rectum during the course of a total colonoscopy. Immunohistochemical analysis was performed using antibodies against phosphorylated alpha-synuclein to detect LN and neurofilaments 200 kDa to label the neuronal structures. Biopsies from ascending, descending colon and rectum were morphologically comparable. LN were detected in the biopsies of ascending colon in 17 PD patients (65%), of descending colon in 11 patients (42%) and of rectum in only 6 patients (23%). No LN were seen in control biopsies. Our results show that Lewy pathology follows a rostrocaudal distribution in the colon and rectum of PD patients. Therefore, rectal biopsies have substantially lower sensitivity than ascending colon biopsies to detect Lewy pathology in the gut.
Neurobiology of Disease 08/2011; 45(1):305-9. · 5.62 Impact Factor
[show abstract][hide abstract] ABSTRACT: Recent reports have demonstrated that interactions between the microtubule-associated protein tau and the nonreceptor tyrosine kinase Fyn play a critical role in mediating synaptic toxicity and neuronal loss in response to β-amyloid (Aβ) in models of Alzheimer's disease. Disruption of interactions between Fyn and tau may thus have the potential to protect neurons from Aβ-induced neurotoxicity. Here, we investigated tau and Fyn interactions and the potential implications for positioning of these proteins in membrane microdomains. Tau is known to bind to Fyn via its Src-homology (SH)3 domain, an association regulated by phosphorylation of PXXP motifs in tau. Here, we show that Pro216 within the PXXP(213-216) motif in tau plays an important role in mediating the interaction of tau with Fyn-SH3. We also show that tau interacts with the SH2 domain of Fyn, and that this association, unlike that of Fyn-SH3, is influenced by Fyn-mediated tyrosine phosphorylation of tau. In particular, phosphorylation of tau at Tyr18, a reported target of Fyn, is important for mediating Fyn-SH2-tau interactions. Finally, we show that tyrosine phosphorylation influences the localization of tau to detergent-resistant membrane microdomains in primary cortical neurons, and that this trafficking is Fyn-dependent. These findings may have implications for the development of novel therapeutic strategies aimed at disrupting the tau/Fyn-mediated synaptic dysfunction that occurs in response to elevated Aβ levels in neurodegenerative disease.
[show abstract][hide abstract] ABSTRACT: Wound healing of the gastrointestinal mucosa is essential for the maintenance of gut homeostasis and integrity. Enteric glial cells play a major role in regulating intestinal barrier function, but their role in mucosal barrier repair remains unknown. The impact of conditional ablation of enteric glia on dextran sodium sulfate (DSS)-induced mucosal damage and on healing of diclofenac-induced mucosal ulcerations was evaluated in vivo in GFAP-HSVtk transgenic mice. A mechanically induced model of intestinal wound healing was developed to study glial-induced epithelial restitution. Glial-epithelial signaling mechanisms were analyzed by using pharmacological inhibitors, neutralizing antibodies, and genetically engineered intestinal epithelial cells. Enteric glial cells were shown to be abundant in the gut mucosa, where they associate closely with intestinal epithelial cells as a distinct cell population from myofibroblasts. Conditional ablation of enteric glia worsened mucosal damage after DSS treatment and significantly delayed mucosal wound healing following diclofenac-induced small intestinal enteropathy in transgenic mice. Enteric glial cells enhanced epithelial restitution and cell spreading in vitro. These enhanced repair processes were reproduced by use of glial-conditioned media, and soluble proEGF was identified as a secreted glial mediator leading to consecutive activation of epidermal growth factor receptor and focal adhesion kinase signaling pathways in intestinal epithelial cells. Our study shows that enteric glia represent a functionally important cellular component of the intestinal epithelial barrier microenvironment and that the disruption of this cellular network attenuates the mucosal healing process.
[show abstract][hide abstract] ABSTRACT: Olfactory dysfunction (OD) and constipation are two frequent and early non-motor features of Parkinson's disease (PD). Colonic PD neuropathology, the putative cause of constipation, can be analyzed and quantified using routine colonic biopsies and parallels disease severity. The present study was aimed at investigating whether the severity of neuropathology in the colon in PD is related to OD. Twenty-six PD patients were included. Colonic neuropathology, i.e., the density of Lewy pathology and the number of submucosal neurons, was unrelated to OD as assessed using the University of Pennsylvania Smell Identification. This suggests that unlike colonic Lewy pathology, OD is unrelated to disease severity.
Journal of Parkinson's disease. 01/2011; 1(4):389-94.
[show abstract][hide abstract] ABSTRACT: Tau protein is the principal component of the neurofibrillary tangles found in Alzheimer's disease, where it is hyperphosphorylated on serine and threonine residues, and recently phosphotyrosine has been demonstrated. The Src-family kinase Fyn has been linked circumstantially to the pathology of Alzheimer's disease, and shown to phosphorylate Tyr18. Recently another Src-family kinase, Lck, has been identified as a genetic risk factor for this disease.
In this study we show that Lck is a tau kinase. In vitro, comparison of Lck and Fyn showed that while both kinases phosphorylated Tyr18 preferentially, Lck phosphorylated other tyrosines somewhat better than Fyn. In co-transfected COS-7 cells, mutating any one of the five tyrosines in tau to phenylalanine reduced the apparent level of tau tyrosine phosphorylation to 25-40% of that given by wild-type tau. Consistent with this, tau mutants with only one remaining tyrosine gave poor phosphorylation; however, Tyr18 was phosphorylated better than the others.
Fyn and Lck have subtle differences in their properties as tau kinases, and the phosphorylation of tau is one mechanism by which the genetic risk associated with Lck might be expressed pathogenically.