Background Tocilizumab blocks pro-inflammatory activity of interleukin-6 (IL-6), involved in pathogenesis of pneumonia the most frequent cause of death in COVID-19 patients. Methods A multicenter, single-arm, hypothesis-driven trial was planned, according to a phase 2 design, to study the effect of tocilizumab on lethality rates at 14 and 30 days (co-primary endpoints, a priori expected rates being 20 and 35%, respectively). A further prospective cohort of patients, consecutively enrolled after the first cohort was accomplished, was used as a secondary validation dataset. The two cohorts were evaluated jointly in an exploratory multivariable logistic regression model to assess prognostic variables on survival. Results In the primary intention-to-treat (ITT) phase 2 population, 180/301 (59.8%) subjects received tocilizumab, and 67 deaths were observed overall. Lethality rates were equal to 18.4% (97.5% CI: 13.6–24.0, P = 0.52) and 22.4% (97.5% CI: 17.2–28.3, P < 0.001) at 14 and 30 days, respectively. Lethality rates were lower in the validation dataset, that included 920 patients. No signal of specific drug toxicity was reported. In the exploratory multivariable logistic regression analysis, older age and lower PaO2/FiO2 ratio negatively affected survival, while the concurrent use of steroids was associated with greater survival. A statistically significant interaction was found between tocilizumab and respiratory support, suggesting that tocilizumab might be more effective in patients not requiring mechanical respiratory support at baseline. Conclusions Tocilizumab reduced lethality rate at 30 days compared with null hypothesis, without significant toxicity. Possibly, this effect could be limited to patients not requiring mechanical respiratory support at baseline. Registration EudraCT (2020-001110-38); clinicaltrials.gov (NCT04317092).

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We have generated a transgenic rat model using RNAi and used it to study the role of the membrane protein Nogo-A in synaptic plasticity and cognition. The membrane protein Nogo-A is expressed in CNS oligodendrocytes and subpopulations of neurons, and it is known to suppress neurite growth and regeneration. The constitutively expressed polymerase II-driven transgene was composed of a micro-RNA-targeting Nogo-A placed into an intron preceding the coding sequence for EGFP, thus quantitatively labeling cells according to intracellular microRNA expression. The transgenic microRNA in vivo efficiently reduced the concentration of Nogo-A mRNA and protein preferentially in neurons. The resulting significant increase in longterm potentiation in both hippocampus and motor cortex indicates a repressor function of Nogo-A in synaptic plasticity. The transgenic rats exhibited prominent schizophrenia-like behavioral phenotypes, such as perseveration, disrupted prepulse inhibition, and strong withdrawal from social interactions. This fast and efficient micro-RNA-mediated knockdown provides a way to silence gene expression in vivo in transgenic rats and shows a role of Nogo-A in regulating higher cognitive brain functions.animal model | Rtn4 | learning | memory G ene knockout (KO) technology has spurred the analysis of gene functions in mice during the past two decades (1) and has recently been expanded to other species using new genome modification technologies (2). Although germ-line gene ablation is a very powerful tool for investigating gene function in vivo, its most important drawback is that the complete loss of gene function often leads to molecular compensation, obscuring the role of the deleted gene. Tissue-or cell-specific KOs are more specific but are currently confined to mice as a model system. RNA interference (RNAi) is a viable alternative to the KO approach and represents a fast and powerful tool for manipulating gene expression (3). RNAi technology not only allows keeping the endogenous genomic locus intact, but it also enables the knockdown of multiple genes at the same time or the selective depletion of a specific isoform of mRNA transcripts (4). Another advantage is offered by the possibility of creating hypomorphic alleles instead of complete KOs, which can avoid embryonic lethality and better mirrors many human diseases and therapeutic interventions.Elucidating gene functions in transgenic rats has several important advantages over using mice (5). Their larger size simplifies interventions, such as microsurgery and multiple site in vivo electrophysiological recordings (6). Furthermore, higher-order cognitive functions are more developed in this social rodent species than in the more solitarily living mice (7,8). Hence, many behavioral tests are more advanced or validated for the rat species, especially regarding the behavioral assessment of complex neuropsychiatric disease phenotypes, such as negative symptoms in schizophrenia.For the rat, only polymerase (Pol) III-controlled shRNA RNAi models have been cre...