A model of human neural networks reveals NPTX2 pathology in ALS and FTLD.

Human cellular models of neurodegeneration require reproducibility and longevity, which is necessary for simulating age-dependent diseases. Such systems are particularly needed for TDP-43 proteinopathies1, which involve human-specific mechanisms2-5 that cannot be directly studied in animal models. Here, to explore the emergence and consequences of TDP-43 pathologies, we generated induced pluripotent stem cell-derived, colony morphology neural stem cells (iCoMoNSCs) via manual selection of neural precursors6. Single-cell transcriptomics and comparison to independent neural stem cells7 showed that iCoMoNSCs are uniquely homogenous and self-renewing. Differentiated iCoMoNSCs formed a self-organized multicellular system consisting of synaptically connected and electrophysiologically active neurons, which matured into long-lived functional networks (which we designate iNets). Neuronal and glial maturation in iNets was similar to that of cortical organoids8. Overexpression of wild-type TDP-43 in a minority of neurons within iNets led to progressive fragmentation and aggregation of the protein, resulting in a partial loss of function and neurotoxicity. Single-cell transcriptomics revealed a novel set of misregulated RNA targets in TDP-43-overexpressing neurons and in patients with TDP-43 proteinopathies exhibiting a loss of nuclear TDP-43. The strongest misregulated target encoded the synaptic protein NPTX2, the levels of which are controlled by TDP-43 binding on its 3' untranslated region. When NPTX2 was overexpressed in iNets, it exhibited neurotoxicity, whereas correcting NPTX2 misregulation partially rescued neurons from TDP-43-induced neurodegeneration. Notably, NPTX2 was consistently misaccumulated in neurons from patients with amyotrophic lateral sclerosis and frontotemporal lobar degeneration with TDP-43 pathology. Our work directly links TDP-43 misregulation and NPTX2 accumulation, thereby revealing a TDP-43-dependent pathway of neurotoxicity.

CD40-TNF activation in mice induces extended sickness behavior syndrome co-incident with but not dependent on activation of the kynurenine pathway.

The similarity between sickness behavior syndrome (SBS) in infection and autoimmune disorders and certain symptoms in major depressive disorder (MDD), and the high co-morbidity of autoimmune disorders and MDD, constitutes some of the major evidence for the immune-inflammation hypothesis of MDD. CD40 ligand-CD40 immune-activation is important in host response to infection and in development of autoimmunity. Mice given a single intra-peritoneal injection of CD40 agonist antibody (CD40AB) develop SBS for 2-3days characterized by weight loss and increased sleep, effects that are dependent on the cytokine, tumor necrosis factor (TNF). Here we report that CD40AB also induces behavioral effects that extend beyond acute SBS and co-occur with but are not mediated by kynurenine pathway activation and recovery. CD40AB led to decreased saccharin drinking (days 1-7) and decreased Pavlovian fear conditioning (days 5-6), and was without effect on physical fatigue (day 5). These behavioral effects co-occurred with increased plasma and brain levels of kynurenine and its metabolites (days 1-7/8). Co-injection of TNF blocker etanercept with CD40AB prevented each of SBS, reduced saccharin drinking, and kynurenine pathway activation in plasma and brain. Repeated oral administration of a selective indoleamine 2,3-dioxygenase (IDO) inhibitor blocked activation of the kynurenine pathway but was without effect on SBS and saccharin drinking. This study provides novel evidence that CD40-TNF activation induces deficits in saccharin drinking and Pavlovian fear learning and activates the kynurenine pathway, and that CD40-TNF activation of the kynurenine pathway is not necessary for induction of the acute or extended SBS effects.

Improved Procedural Efficiency of Atrial Fibrillation Ablation Using a Dedicated Ablation Protocol and Lean Management.

OBJECTIVES: In this study the authors hypothesized that "Lean management" within a dedicated ablation protocol could standardize the pulmonary vein isolation (PVI) procedure and improve quality. BACKGROUND: There is a large variability in safety, effectiveness, and efficiency of PVI. METHODS: This was a single-center prospective study with inclusion of all consecutive PVI procedures from 2017 to 2019. A 3-step intervention was introduced based on Lean management: step 1) simplification (CLOSE protocol); step 2) waste elimination (higher power shorter duration); and step 3) improved standardization (Lab Optimization Tool [LOT]). PVI was divided into steps that were tracked (in minutes) using LOT. Parameters were compared in 6-month intervals. RESULTS: Overall, 295 patients (146 patients with LOT) were analyzed. Step 1 reduced skin-to-skin procedure duration (2017: 119 ± 21 min vs. 2018: 77 ± 15 min; p < 0.001) and variance (from 2018 to 2019 p = 0.024). Step 2 reduced the radiofrequency time (2017: 38 ± 6 min vs. 2018: 20 ± 3 min; p < 0.001) and variance (from 2018 to 2019 p < 0.001). Analysis of step 3 demonstrated that only 53% of the entire procedure length (143 ± 22 min) was used for treatment (skin-to-skin time 77 ± 16 min), the remaining time being devoted for setup (42 ± 12 min, 29%); left atrial access (16 ± 7 min, 12%); respiratory gating, left atrial map, and pseudo-circle annotation (10 ± 6 min, 7%); ablation (39 ± 10 min, 27%); and bilateral block validation (10 ± 8 min, 7%). CONCLUSIONS: Standardization of PVI using a dedicated ablation protocol and Lean management can help to reduce procedure and radiofrequency ablation duration and variance, and increase procedural efficiency without compromising safety. To improve health care utilization, increased efficiency should become an accepted goal in addition to procedural safety and effectiveness.