Estudio de la unión neuromuscular en el origen patogénico de la ELA

La esclerosis lateral amiotrófica (ELA) es una enfermedad neurodegenerativa progresiva que afecta rápidamente a las motoneuronas del cerebro y la médula espinal. Esta enfermedad, a día de hoy, no tiene cura. En alrededor del 90% de los casos el origen de la enfermedad es desconocido, pero en un 10% está causada por mutaciones genéticas de herencia mendeliana en más de 20 genes, entre los que destacan TARBDP, que codifica para TDP-43, y FUS. Recientes hallazgos han cuestionado el origen neurogénico de la enfermedad para situarlo en las células sostén de las motoneuronas dentro del sistema neuromuscular, como lo son las células de la glía y las células del músculo esquelético. Con el objetivo de tratar de esclarecer si el origen patogénico en la motoneurona es suficiente para causar enfermedad de ELA se ha llevado a cabo la generación y caracterización de dos modelos de Drosophila melanogaster que reproducen uno de los principales detonantes de la enfermedad, la pérdida de función del ortólogo de TDP-43 (Tbph) o FUS (Caz), en motoneurona mediante el silenciamiento condicionado de dichos genes en este tipo celular. Además, se ha comprobado la validez de estos modelos para ensayos de testado farmacológico usando un tratamiento con demostrada capacidad de proteger frente a los efectos de la disfunción de TDP-43 y FUS: la inhibición de FoxO. Los resultados muestran un déficit locomotor característico de la ELA en el modelo generado con el promotor de la proteína OK6, sin variaciones acordes en su longevidad. Dicho modelo fue tratado con un inhibidor selectivo de FoxO, AS1842856, el cual fue capaz de mitigar las anomalías locomotoras detectadas en las moscas con silenciamiento de Tbph. A falta de realizar estudios histopatológicos que demuestren neurodegeneración de motoneurona, se puede extraer de los presentes resultados que los modelos de inducción de pérdida de función de Tbph y Caz en motoneurona de Drosophila son capaces de provocar fenotipos compatibles con la ELA, y por tanto son legítimos para realizar tratamientos farmacológicos. Además, la inhibición de los factores de transcripción FoxO a nivel de motoneurona tiene efectos beneficiosos como tratamiento de la enfermedad.<br /

Evaluation of cholinergic markers in Alzheimer's disease and in a model of cholinergic deficit

Cognitive deficits in neuropsychiatric disorders, such as Alzheimer's disease (AD), have been closely related to cholinergic deficits. We have compared different markers of cholinergic function to assess the best biomarker of cognitive deficits associated to cholinergic hypoactivity. In post-mortem frontal cortex from AD patients, acetylcholine (ACh) levels, cholinacetyltransferase (ChAT) and acetylcholinesterase (AChE) activity were all reduced compared to controls. Both ChAT and AChE activity showed a significant correlation with cognitive deficits. In the frontal cortex of rats with a selective cholinergic lesion, all cholinergic parameters measured (ACh levels, ChAT and AChE activities, "in vitro" and "in vivo" basal ACh release) were significantly reduced. AChE activity was associated to ChAT activity, and even more, to "in vivo" and "in vitro" basal ACh release. Quantification of AChE activity is performed by an easy and cheap method and therefore, these results suggest that determination of AChE activity may be used as an effective first step method to evaluate cholinergic deficits

Facilitation of cholinergic transmission by combined treatment of ondansetron with flumazenil after cortical cholinergic deafferentation

We have studied the effects of concomitant blockade of 5-HT(3) and GABA(A) receptors on acetylcholine (ACh) release in the frontal cortex of rats with a selective cholinergic lesion. Lesions were performed by microinjection of the cholinergic toxin 192 IgG-saporin into the nucleus basalis magnocellularis. Single treatment with either the 5-HT(3) receptor antagonist ondansetron, 0.1 microg/kg, or the GABA(A) receptor benzodiazepine site antagonist flumazenil, 10 mg/kg, did not affect ACh release. However, the combined ondansetron + flumazenil administration significantly increased ACh release to a similar extent as a depolarising stimulus with K(+), 100 mM, at both 7 and 30 days post-lesion. Cortical perfusion with the combined ondansetron + flumazenil treatment also increased [(3)H]ACh efflux "in vitro" 30 days after lesion, suggesting that local events within the frontal cortex may participate in the interaction of ondansetron with GABAergic neurons, modulating ACh release in situations of cholinergic hypoactivity. No differences in the expression of 5-HT(3) and GABA(A) receptors in the frontal cortex were found after the cholinergic lesion. These results suggest that a combined ondansetron + flumazenil treatment would contribute to restoring a diminished cholinergic function and may provide a basis for using this treatment in the therapy of cognitive disorders associated with degeneration of the cholinergic system

Insulin levels are decreased in the cerebrospinal fluid of women with prodomal Alzheimer's disease

Previous studies have failed to reach consensus on insulin levels in cerebrospinal fluid of Alzheimer's disease (AD) patients and on its relation to pathological features. We performed a new analysis in patients at different stages of AD, and investigated the relationship of insulin levels with biochemical disease markers and with cognitive score. We included 99 patients from our Memory Clinic (Karolinska University Hospital, Sweden), including: 27 patients with mild AD, 13 that progressed from mild cognitive impairment (MCI) to AD in two years time, 26 with MCI stable after two years, and 33 with subjective cognitive impairment. Insulin was significantly decreased in the cerebrospinal fluid of both women and men with mild AD. Insulin deficits were seen in women belonging to both MCI groups, suggesting that this occurs earlier than in men. Insulin was positively associated with amyloid-β 1-42 (Aβ1-42) levels and cognitive score. Furthermore, total-tau/(Aβ1-42*insulin) ratio showed strikingly better sensitivity and specificity than the total-tau/Aβ1-42 ratio for early AD diagnosis in women

Cholinergic-serotonergic imbalance contributes to cognitive and behavioral symptoms in Alzheimer's disease

Neuropsychiatric symptoms seen in Alzheimer's disease (AD) are not simply a consequence of neurodegeneration, but probably result from differential neurotransmitter alterations, which some patients are more at risk of than others. Therefore, the hypothesis of this study is that an imbalance between the cholinergic and serotonergic systems is related to cognitive symptoms and psychological syndromes of dementia (BPSD) in patients with AD. Cholinergic and serotonergic functions were assessed in post-mortem frontal and temporal cortex from 22 AD patients who had been prospectively assessed with the Mini-Mental State examination (MMSE) for cognitive impairment and with the Present Behavioral Examination (PBE) for BPSD including aggressive behavior, overactivity, depression and psychosis. Not only cholinergic deficits, but also the cholinacetyltransferase/serotonin ratio significantly correlated with final MMSE score both in frontal and temporal cortex. In addition, decreases in cholinergic function correlated with the aggressive behavior factor, supporting a dual role for the cholinergic system in cognitive and non-cognitive disturbances associated to AD. The serotonergic system showed a significant correlation with overactivity and psychosis. The ratio of serotonin to acetylcholinesterase levels was also correlated with the psychotic factor at least in women. It is concluded that an imbalance between cholinergic-serotonergic systems may be responsible for the cognitive impairment associated to AD. Moreover, the major findings of this study are the relationships between neurochemical markers of both cholinergic and serotonergic systems and non-cognitive behavioral disturbances in patients with dementia

Altered NCAM expression associated with the cholinergic system in Alzheimer's disease

Neurotransmitter system dysfunction and synapse loss have been recognized as hallmarks of Alzheimer's disease (AD). Our hypothesis is that specific neurochemical populations of neurons might be more vulnerable to degeneration in AD due to particular deficits in synaptic plasticity. We have studied, in postmortem brain tissue, the relationship between levels of synaptic markers (NCAM and BDNF), neurochemical measurements (cholinacetyltransferase activity, serotonin, dopamine, GABA, and glutamate levels), and clinical data (cognitive status measured as MMSE score). NCAM levels in frontal and temporal cortex from AD patients were significantly lower than control patients. Interestingly, these reductions in NCAM levels were associated to an ApoE4 genotype. Levels of BDNF were also significantly reduced in both frontal and temporal regions in AD patients. The ratio between plasticity markers and neurochemical measurements was used to study which of the neurochemical populations was particularly associated to plasticity changes. In both the frontal and temporal cortex, there was a significant reduction in the ChAT/NCAM ratio in AD samples compared to controls. None of the ratios to BDNF were different between control and AD samples. Furthermore, Pearson's product moment showed a significant positive correlation between MMSE score and the ChAT/NCAM ratio in frontal cortex (n=19; r=0.526*; p=0.037) as well as in temporal cortex (n=19; r=0.601*; p=0.018) in AD patients. Altogether, these data suggest a potential involvement of NCAM expressing neurons in the cognitive deficits in AD

Involvement of an altered 5-HT -{6} receptor function in behavioral symptoms of Alzheimer's disease

We studied the hypothesis that disturbances in 5-HT_{6} receptor function in the temporal cortex may contribute to clinical symptoms of Alzheimer's disease (AD). 5-HT_{6} density and 5-HT levels were significantly decreased in a cohort of AD patients prospectively assessed for cognitive/behavioral symptoms. cAMP formation after stimulation with the selective 5-HT_{6} receptor agonist E-6801 was significantly lower (p<0.01) in AD (170.02 +/- 27.53 pmol/mg prot.) compared to controls (823.33 +/-196.67). In addition, the ratio cAMP formation after stimulation with E-6801/5-HT_{6} receptor density was significantly lower (p< 0.01) in AD (6.67 +/- 0.83) compared to controls (16.67 +/- 3.33). Splitting these results by sex, 5-HT_{6} receptor activation was significantly lower (p< 0.01) in AD females compared to males (121.67 +/- 30.02 vs. 231.67 +/- 34.17 pmol/mg prot). 5-HT_{6} density and 5-HT levels were significantly correlated (p < or = 0.01) in both controls and AD patients, although in AD, this correlation was lost in females. Psychosis factor was the best predictor of reduced 5-HT levels or adenylate cyclase activity after E-6801 stimulation, the former result being due to females. It may be suggested that psychotic symptoms may be related to a dysregulation of 5-HT_{6} activation by 5-HT in the temporal cortex. These results are discussed in terms of purported influence of sex and therapeutical approaches to psychosis in AD

Elevated cholesterol in ATAD3 mutants is a compensatory mechanism that leads to membrane cholesterol aggregation

Aberrant cholesterol metabolism causes neurological disease and neurodegeneration, and mitochondria have been linked to perturbed cholesterol homeostasis via the study of pathological mutations in the ATAD3 gene cluster. However, whether the cholesterol changes were compensatory or contributory to the disorder was unclear, and the effects on cell membranes and the wider cell were also unknown. Using patient-derived cells, we show that cholesterol perturbation is a conserved feature of pathological ATAD3 variants that is accompanied by an expanded lysosome population containing membrane whorls characteristic of lysosomal storage diseases. Lysosomes are also more numerous in Drosophila neural progenitor cells expressing mutant Atad3, which exhibit abundant membrane-bound cholesterol aggregates, many of which co-localize with lysosomes. By subjecting the Drosophila Atad3 mutant to nutrient restriction and cholesterol supplementation, we show that the mutant displays heightened cholesterol dependence. Collectively, these findings suggest that elevated cholesterol enhances tolerance to pathological ATAD3 variants; however, this comes at the cost of inducing cholesterol aggregation in membranes, which lysosomal clearance only partly mitigates.M.M.O. was supported by a predoctoral fellowship from the University of the Basque Country (PIF18/317) and later partially supported by the Ikerbasque, Basque Foundation for Science IKUR strategy Neurodegenprot project. A.L. and U.F.P. were recipients of pre-doctoral fellowships from the Basque Government (PRE_2019_1_0184 and PRE_2018_1_0253). The study was supported by funding to I.J.H. from the Instituto de Salud Carlos III (PI17-00380; PI20/00096) and the Basque Government Department of Health (Osasun Saila, Eusko Jaurlaritzako) (grants 2021111070; 2022333050; 2018111043; 2018222031). A.Sp. receives support from Miriam Marks Senior Fellowship, Brain Research UK (202021-26), the Research Councils UK (MR/X002365/1) and the Lily Foundation. W.H.Y. is supported by the National Institute of Neurological Disorders and Stroke (5R01 NS121298-03) of the National Institutes of Health, Oklahoma Center for Adult Stem Cell Research (OCASCR) (221009 and 241006) and Presbyterian Health Foundation (4411-09-10-0).Peer reviewe

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio