Marie-Hélène Canron

Altered M1/M2 activation patterns of monocytes in severe relapsing experimental rat model of Multiple Sclerosis. Amelioration of clinical status by M2 activated monocyte administration

Objectives:We investigated proinflammatory M1 and immunomodulatory M2 activation profiles of circulating monocytes in relapsing experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis, and tested whether altered M1/M2 equilibrium promotes CNS inflammation. Results:Approaches of MRI macrophage tracking with USPIO nanoparticles and expression patterns of M1/M2 macrophages and microglia in brain and M1/M2 monocytes in blood samples at various disease stages revealed that M1/M2 equilibrium in blood and CNS favors mild EAE, while imbalance towards M1 promotes relapsing EAE. We consequently investigated whether M2 activated monocyte restoration in peripheral blood could cure acute clinical EAE disease. Administration of ex vivo activated M2 monocytes both suppressed ongoing severe EAE and increased immunomodulatory expression pattern in lesions, confirming their role in the induction of recovery. Conclusion:We conclude that imbalance of monocyte activation profiles and impaired M2 expression, are key factors in development of relapses. Our study opens new perspectives for therapeutic applications in MS.

Loss of P-type ATPase ATP13A2/PARK9 function induces general lysosomal deficiency and leads to Parkinson disease neurodegeneration

Parkinson disease (PD) is a progressive neurodegenerative disorder pathologically characterized by the loss of dopaminergic neurons from the substantia nigra pars compacta and the presence, in affected brain regions, of protein inclusions named Lewy bodies (LBs). The ATP13A2 gene (locus PARK9) encodes the protein ATP13A2, a lysosomal type 5 P-type ATPase that is linked to autosomal recessive familial parkinsonism. The physiological function of ATP13A2, and hence its role in PD, remains to be elucidated. Here, we show that PD-linked mutations in ATP13A2 lead to several lysosomal alterations in ATP13A2 PD patient-derived fibroblasts, including impaired lysosomal acidification, decreased proteolytic processing of lysosomal enzymes, reduced degradation of lysosomal substrates, and diminished lysosomal-mediated clearance of autophagosomes. Similar alterations are observed in stable ATP13A2-knockdown dopaminergic cell lines, which are associated with cell death. Restoration of ATP13A2 levels in ATP13A2-mutant/depleted cells restores lysosomal function and attenuates cell death. Relevant to PD, ATP13A2 levels are decreased in dopaminergic nigral neurons from patients with PD, in which ATP13A2 mostly accumulates within Lewy bodies. Our results unravel an instrumental role of ATP13A2 deficiency on lysosomal function and cell viability and demonstrate the feasibility and therapeutic potential of modulating ATP13A2 levels in the context of PD.

Combined nerve and muscle biopsy in the diagnosis of vasculitic neuropathy. A 16‐year retrospective study of 202 cases

Abstract  We reviewed 202 biopsies performed on patients with suspected vasculitic neuropathy, of which 24 Churg‐Strauss cases are studied separately. Specimens from the superficial peroneal nerve and peroneus brevis muscle were taken simultaneously by one incision. Without taking into account constitutional signs, systemic involvement was present in 131 patients, whereas the remaining 47 corresponded to non‐systemic patients with lesions limited to peripheral nervous system and adjoining muscles. Diagnosis of panarteritis nodosa or microscopic polyangiitis, according to the size of involved vessels, was attested by an infiltration of vessel walls by inflammatory cells associated with fibrinoid necrosis or sclerosis. Microvasculitis was diagnosed when inflammatory infiltration concerned small vessels with few or no smooth‐muscle fibers and without any necrosis. Microvasculitis was present in 11 of 46 non‐systemic cases, and this predominance is statistically significant. Isolated perivascular cell infiltrates in the epineurium were considered not significant but allowed the diagnosis of ‘probable vasculitis’ if associated with at least one of the following features: regenerating small vessels, endoneurial purpura, asymmetric nerve fiber loss, and/or asymmetric acute axonal degeneration. Necrotizing vasculitis was visible in 60 cases: in nerve (16 cases), in muscle (19 cases), and both (25 cases). Microvasculitis was present in 25 cases: in nerve (19 cases), muscle (four cases), or both (two cases). Moreover, granulomatous vasculitis was found in the nerve of one non‐systemic patient presenting also sarcoid granulomas in muscle. There were 24 ‘probable vasculitis’ and 68 negative cases. Muscle biopsy improved the yield of definite vasculitis by 27%.

Protein Aggregation in the Aging Retina

The age-related altered expression of neuron-related proteins as seen in other regions of the central nervous system is expected in the aging retina. Using immunohistochemical techniques, we characterized the distribution and aggregation of tau, &bgr;A4-amyloid, &agr;-synuclein, and ubiquitin in human retina obtained from 19 enucleated eyes of patients aged 49 to 87 years and correlated the findings with the ages. Using a phosphorylation-independent antibody, tau aggregates were observed within the cytoplasm of several photoreceptor cells, and there was a positive correlation between age and the number of tau-positive ganglionic cells. Tau deposits were immunonegative with a phosphorylation-dependent antibody. We did not observe &bgr;A4-amyloid in subretinal pigment epithelium deposits or in neuroepithelial layers. &agr;-Synuclein and ubiquitin inclusions were found in the inner nuclear layer, and there was colocalization of these proteins. The proportion of patients displaying such &agr;-synuclein and/or ubiquitin intracytoplasmic inclusions was significantly higher with aging. The presence of ubiquitin deposits within drusen was remarkable, but diffuse ubiquitin aggregates between the retinal pigment epithelium and Bruch membrane were also noticed. These results indicate that protein aggregation in the retina increases with aging and that tau, &agr;-synuclein, and ubiquitin should be the subjects of future investigations.

Postvaccinal inflammatory neuropathy: peripheral nerve biopsy in 3 cases

Abstract  Autoimmune inflammatory polyneuropathy (PN) can be triggered by vaccination. We report 3 such cases. A 36‐year‐old female nurse presented 15 days after a hepatitis B vaccination (HBV) with acute sensory disturbances in the lower limbs. She had severe ataxia but no weakness. Cerebrospinal fluid (CSF) protein level was 84 mg/100 mL, with 3 lymphocytes. A 66‐year‐old man presented 21 days after HBV with severe motor and sensory PN involving all 4 limbs. A 66‐year‐old man presented 15 days after a yellow fever vaccination with progressive motor and sensory PN involving all 4 limbs and bilateral facial paralysis. CSF protein level was 300 mg/100 mL, with 5 lymphocytes. Six weeks later, a tracheostomy was performed. In these 3 patients, the nerve deficits lasted for months. In each case, peripheral nerve biopsy showed KP1‐positive histiocytes but no T‐lymphocytes in the endoneurium. On ultrastructural examination, there was axonal degeneration in the first 2 cases; in case 2, a few myelinated fibers exhibited an intra‐axonal macrophage but the myelin sheath was preserved. There was only 1 example of macrophage‐associated demyelination in case 2, but these were numerous in case 3. It is likely that in the first 2 cases, an autoimmune reaction against some axonal or neuronal components was triggered by HBV. It induced an acute sensory ataxic PN in case 1 and an acute motor and sensory axonal neuropathy (AMSAN) in case 2. The third patient had a chronic inflammatory demyelinating PN, likely triggered by yellow fever vaccination.

Anti-myelin-associated glycoprotein antibodies and endoneurial cryoglobulin deposits responsible for a severe neuropathy

Abstract. A 73-year-old man was investigated for a peripheral neuropathy which occurred in the course of a Waldenströms macroglobulinemia. Serum immuno-fixation electrophoresis demonstrated two IgM monoclonal gammopathies of the kappa and lambda chain isotypes, and one had the physical characteristics of cryoglobulin. Immunoblot studies on the patients serum revealed antibodies which reacted with peripheral nervous system proteins of different molecular weights including the myelin-associated glycoprotein (MAG). An immunofluorescence study of a superficial peroneal nerve biopsy revealed not only a binding of IgM and kappa light chain on several myelin sheaths but also the presence of IgM and kappa light chain deposits in the endoneurium. On electron microscopic examination, numerous fibres presented a widely spaced myelin and the endoneurial deposits had the ultrastructure of cryoglobulin. This is the first case presenting features of widely spaced myelin related to serum anti-MAG activity associated with monoclonal cryoglobulin deposits in the endoneurium.

Astrocytosis in parkinsonism: considering tripartite striatal synapses in physiopathology?

The current concept of basal ganglia organization and function in physiological and pathophysiological conditions excludes the most numerous cells in the brain, i.e., the astrocytes, present with a ratio of 10:1 neuron. Their role in neurodegenerative condition such as Parkinson’s disease (PD) remains to be elucidated. Before embarking into physiological investigations of the yet-to-be-identified “tripartite” synapses in the basal ganglia in general and the striatum in particular, we therefore characterized anatomically the PD-related modifications in astrocytic morphology, the changes in astrocytic network connections and the consequences on the spatial relationship between astrocytic processes and asymmetric synapses in normal and PD-like conditions in experimental and human PD. Our results unravel a dramatic regulation of striatal astrocytosis supporting the hypothesis of a key role in (dys) regulating corticostriatal transmission. Astrocytes and their various properties might thus represent a therapeutic target in PD.

Endogenous morphine-like compound immunoreactivity increases in parkinsonism

Morphine is endogenously synthesized in the central nervous system and endogenous dopamine is thought to be necessary for endogenous morphine formation. As Parkinsons disease results from the loss of dopamine and is associated with central pain, we considered how endogenous morphine is regulated in the untreated and l-DOPA-treated parkinsonian brain. However, as the cellular origin and overall distribution of endogenous morphine remains obscure in the pathological adult brain, we first characterized the distribution of endogenous morphine-like compound immunoreactive cells in the rat striatum. We then studied changes in the endogenous morphine-like compound immunoreactivity of medium spiny neurons in normal, Parkinsons disease-like and l-DOPA-treated Parkinsons disease-like conditions in experimental (rat and monkey) and human Parkinsons disease. Our results reveal an unexpected dramatic upregulation of neuronal endogenous morphine-like compound immunoreactivity and levels in experimental and human Parkinsons disease, only partially normalized by l-DOPA treatment. Our data suggest that endogenous morphine formation is more complex than originally proposed and that the parkinsonian brain experiences a dramatic upregulation of endogenous morphine immunoreactivity. The functional consequences of such endogenous morphine upregulation are as yet unknown, but based upon the current knowledge of morphine signalling, we hypothesize that it is involved in fatigue, depression and pain symptoms experienced by patients with Parkinsons disease.

Insulin resistance and exendin-4 treatment for multiple system atrophy.

See Stayte and Vissel (doi:10.1093/awx064) for a scientific commentary on this article. Multiple system atrophy is a fatal sporadic adult-onset neurodegenerative disorder with no symptomatic or disease-modifying treatment available. The cytopathological hallmark of multiple system atrophy is the accumulation of α-synuclein aggregates in oligodendrocytes, forming glial cytoplasmic inclusions. Impaired insulin/insulin-like growth factor-1 signalling (IGF-1) and insulin resistance (i.e. decreased insulin/IGF-1) have been reported in other neurodegenerative disorders such as Alzheimers disease. Increasing evidence also suggests impaired insulin/IGF-1 signalling in multiple system atrophy, as corroborated by increased insulin and IGF-1 plasma concentrations in multiple system atrophy patients and reduced IGF-1 brain levels in a transgenic mouse model of multiple system atrophy. We here tested the hypothesis that multiple system atrophy is associated with brain insulin resistance and showed increased expression of the key downstream messenger insulin receptor substrate-1 phosphorylated at serine residue 312 in neurons and oligodendrocytes in the putamen of patients with multiple system atrophy. Furthermore, the expression of insulin receptor substrate 1 (IRS-1) phosphorylated at serine residue 312 was more apparent in inclusion bearing oligodendrocytes in the putamen. By contrast, it was not different between both groups in the temporal cortex, a less vulnerable structure compared to the putamen. These findings suggest that insulin resistance may occur in multiple system atrophy in regions where the neurodegenerative process is most severe and point to a possible relation between α-synuclein aggregates and insulin resistance. We also observed insulin resistance in the striatum of transgenic multiple system atrophy mice and further demonstrate that the glucagon-like peptide-1 analogue exendin-4, a well-tolerated and Federal Drug Agency-approved antidiabetic drug, has positive effects on insulin resistance and monomeric α-synuclein load in the striatum, as well as survival of nigral dopamine neurons. Additionally, plasma levels of exosomal neural-derived IRS-1 phosphorylated at serine residue 307 (corresponding to serine residue 312 in humans) negatively correlated with survival of nigral dopamine neurons in multiple system atrophy mice treated with exendin-4. This finding suggests the potential for developing this peripheral biomarker candidate as an objective outcome measure of target engagement for clinical trials with glucagon-like peptide-1 analogues in multiple system atrophy. In conclusion, our observation of brain insulin resistance in multiple system atrophy patients and transgenic mice together with the beneficial effects of the glucagon-like peptide-1 agonist exendin-4 in transgenic mice paves the way for translating this innovative treatment into a clinical trial.

The nigrostriatal pathway in Creutzfeldt-Jakob disease.

Parkinsonism, chorea, and dystonia are well-known clinical manifestations of Creutzfeldt-Jakob disease (CJD), but lesions of the nigrostriatal pathway have never been thoroughly studied. We performed a detailed neuropathologic study of the nigrostriatal pathway in 15 sporadic CJD and 2 variant CJD cases that included clinical correlations and assessment of neuron subtype loss, distribution of prion protein, &agr;-synuclein, ubiquitin, and 14-3-3 aggregation. We found evidence of nigrostriatal pathway damage in these CJD cases. Dopaminergic neurons and striatal outflow neurons were markedly affected in sporadic CJD, whereas cholinergic interneurons were spared. In cases of CJD with chorea or myoclonus, there was less presynaptic dopaminergic loss than in cases of CJD with parkinsonism. The 2 variant CJD cases with parkinsonism or chorea showed severe cholinergic interneuron loss in the caudate and putamen, a pattern that differed from that found in sporadic CJD. &agr;-Synuclein, ubiquitin, and 14-3-3 aggregation coexisted with prion protein aggregation, thereby generating mixed pathological features. These findings suggest a possible pathophysiological overlap of abnormal protein aggregation in CJD and Parkinson disease.