TSPO Modulates Oligomeric Amyloid-ß-Induced Monocyte Chemotaxis: Relevance for Neuroinflammation in Alzheimer's Disease.

BACKGROUND: Neuroinflammation is one of the cardinal mechanisms of Alzheimer's disease (AD). with amyloid-ß (Aß) playing a critical role by activating microglia to produce soluble inflammatory mediators, including several chemokines. Peripheral monocytes are, therefore, attracted into the central nervous system (CNS), where they change into blood-born microglia and participate in the attempt of removing toxic Aß species. The translocator protein-18 kDa (TSPO) is a transmembrane protein overexpressed in response to neuroinflammation and known to regulate human monocyte chemotaxis. OBJECTIVE: We aimed to evaluate the role of the oligomeric Aß1-42 isoform at inducing peripheral monocyte chemotaxis, and the possible involvement of TSPO in this process. METHODS: In vitro cell lines, and ex vivo monocytes from consecutive AD patients (n = 60), and comparable cognitively intact controls (n = 30) were used. Chemotaxis analyses were carried out through both µ-slide chambers and Boyden assays, using 125 pM oligomeric Aß1-42 as chemoattractant. TSPO agonists and antagonists were tested (Ro5-4864, Emapunil, PK11195). RESULTS: Oligomeric Aß directly promoted chemotaxis in all our models. Interestingly, AD monocytes displayed a stronger response (about twofold) with respect to controls. Aß-induced chemotaxis was prevented by the TSPO antagonist PK11195; the expression of the TSPO and of the C-C chemokine receptor type 2 (CCR2) was unchanged by drug exposure. CONCLUSION: Oligomeric Aß1-42 is able to recruit peripheral monocytes, and we provide initial evidence sustaining a role for TSPO in modulating this process. This data may be of value for future therapeutic interventions aimed at modulating monocytes motility toward the CNS.

Hypoglycemic Encephalopathy Manifesting with Cortical Hemichorea-Hemiballismus Syndrome: A Case Report.

Hyper-/hypoglycemic states are rare but well-established causes of hyperkinetic movements, including chorea and ballismus, usually associated with brain lesions in the basal ganglia. We report a case of hemichorea-hemiballismus (HCHB) syndrome that developed after a severe hypoglycemic episode in a 71-year-old man with poorly controlled type 2 diabetes mellitus. Uncommonly, brain MRI showed contralateral cortical-subcortical T2 and T2-FLAIR-hyperintense frontoparietal lesions, with cingulate gyrus involved, while the basal ganglia were unaffected. In patients with hypoglycemic encephalopathy associated with cortical lesions, the long-term prognosis is usually poor. Nevertheless, in our patient, the dyskinesias and the cerebral lesions progressively regressed by achieving good glycemic control. After four and 12 months, the patient's neurological examination was normal. To our knowledge, this is the first evidence of hypoglycemic etiology of cortical HCHB syndrome, supporting recent theories that cortical circuitries may independently contribute to the pathogenesis of chorea and ballismus. This is also the first report of cingulate gyrus involvement in hypoglycemic encephalopathy. Finally, this case may indicate that a subset of patients with cortical lesions due to hypoglycemia could present a good clinical outcome, likely depending on the size of the lesions and the duration and severity of the hypoglycemic episode.

Coming to Terms with a Conundrum: A Case of Primary Progressive Apraxia of Speech due to Corticobasal Degeneration?

Primary progressive apraxia of speech (PPAOS) is a progressive disorder impairing the motor speech act leaving linguistic function unattained. Although apraxia of speech frequently co-occurs with other neurodegenerative conditions, PPAOS defines a clinical syndrome where apraxia of speech is the sole or prominent symptom for much of the disease's natural history. Mounting evidence is beginning to fully define this disease as the epiphenomenon of 4-repeat (4R) tau pathology although other pathologic signatures have been reported. Indeed, PPAOS patients generally present a parkinsonian syndrome late into their natural history mostly qualifying for either corticobasal syndrome (CBS) or progressive supranuclear palsy (PSP). This is starting to be reflected in diagnostic criteria for PSP, namely, in the PSP speech and language (SL) subcategory; however, this inclusion is not reflected for CBS. Here, we present a single case of a patient with PPAOS and her clinical follow-up lasting 6 years, from the time she sought our attention to her death which occurred 8 years into the disease. PPAOS was the only and prominent symptom for most of the illness with extrapyramidal signs overtly presenting in the last months of its course. Clinical evaluation, imaging, genetic, and cerebrospinal fluid biomarkers all pointed toward an underlying CBD pathology, albeit the eventual anatomopathological confirmation was not performed. Had her clinical course been more suggestive of PSP, she would have qualified for criteria as PSP-SL. Our case therefore suggests the hypothetic need to discuss the broadening of the existing CBS criteria to encompass isolated PPAOS.