Circuit-selective cell-autonomous regulation of inhibition in pyramidal neurons by Ste20-like kinase

Maintaining an appropriate balance between excitation and inhibition is critical for neuronal information processing. Cortical neurons can cell-autonomously adjust the inhibition they receive to individual levels of excitatory input, but the underlying mechanisms are unclear. We describe that Ste20-like kinase (SLK) mediates cell-autonomous regulation of excitation-inhibition balance in the thalamocortical feedforward circuit, but not in the feedback circuit. This effect is due to regulation of inhibition originating from parvalbumin-expressing interneurons, while inhibition via somatostatin-expressing interneurons is unaffected. Computational modeling shows that this mechanism promotes stable excitatory-inhibitory ratios across pyramidal cells and ensures robust and sparse coding. Patch-clamp RNA sequencing yields genes differentially regulated by SLK knockdown, as well as genes associated with excitation-inhibition balance participating in transsynaptic communication and cytoskeletal dynamics. These data identify a mechanism for cell-autonomous regulation of a specific inhibitory circuit that is critical to ensure that a majority of cortical pyramidal cells participate in information coding

P378 Oxidative status and antioxidant capacity in children and adults with IBD: preliminary results of the OxIBDiet trial

Abstract Background Redox imbalance is involved in several aspects of inflammatory bowel disease (IBD). The OxIBDiet (NCT04513015) is a multicentre, 2-phases project involving IBD children and adults with the following aims: 1. To evaluate oxidative status of IBD subjects. 2. To estimate the effects of an antioxidant diet in IBD patients. Preliminary results are shown in this abstract. Methods The total antioxidant capacity, lipid peroxidation and the degree of protein oxidation were measured respectively through the ferric reducing ability of plasma (FRAP, µmol/equivalent FeSO4), serum levels of the thiobarbituric acid reactive substances (TBARs, µmol MDA) and advanced Oxidation Protein Products (AOPP, µmol/g protein). Reactive oxygen species (ROS, Arbitrary Units) and activities (nmol/min/mg of protein) of the main antioxidant enzymes, superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione reductase (GR), glutathione S-Transferase (GST) and catalases (CAT) were evaluated in PMNs cells. Oxidative stress markers were correlated with demographic variables and clinical parameters. Results Fifteen adults (mean age: 36.2 ±11.4 years, 47% female, 67% in remission) and thirty five children (mean age: 14.13 ±2.2 years, 60% female, 65% in remission) with IBD have been enrolled so far. FRAP was significantly reduced in IBD children compared to healthy controls (median values: 212.1 vs. 248.3, p=0.0001) and to IBD adults (median value: 281, p<0.001), while no difference was observed between adults with IBD and the control group (p= 0.1). ROS levels did not differ in IBD children compared to adults and controls. The activity of GPX and CAT enzymes was increased in children with IBD in comparison to controls (p:0.02 and 0.001, respectively) while the activity of the other enzymes (GST, GR and SOD) and levels of lipid peroxidation and protein oxidation was not different between the 2 groups. Overall in the IBD group (children plus adults) FRAP was positively correlated with age (r=0.40, p=0.006), male gender (r=0.33, p=0.03) and use of biologics (r=0.47, p=0.001) and inversely correlated to disease activity based on clinical scores (r= -0.38, p=0.009). No correlation was found between FRAP and serum C-reactive protein or calprotectin levels. Conclusion The total antioxidant capacity (FRAP) is significantly impaired in IBD children respect to IBD adults and to healthy controls, thus suggesting an early involvement of oxidative stress in IBD pathogenesis. Moreover, the activity of the main antioxidant enzymes (GPx and CAT) in IBD children is increased, as a possible compensation for redox imbalance. Final results will clarify the involvement of antioxidant cascade in IBD pathogenesis and in therapeutic approach

Supplementary Material for: Neurochemical profile of BRAFV600E/AktT308D/S473D mouse gangliogliomas reveals impaired GABAergic system inhibition

Gangliogliomas (GGs), composed of dysmorphic neurons and neoplastic astroglia, represent the most frequent tumor entity associated with chronic recurrent epileptic seizures. So far, a systematic analysis of potential differences in neurochemical profiles of dysmorphic tumoral neurons as well as neurons of the peritumoral microenvironment (PTME) was hampered by the inability to unequivocally differentiate between the distinct neuronal components in human GG biopsies. Here, we have applied a novel GG mouse model that allows to clearly resolve the neurochemical profiles of GG-intrinsic versus PTME neurons. For this purpose, glioneuronal tumors in mice were induced by intraventricular in utero electroporation (IUE) of piggyBac-based plasmids for BRAFV600E and activated Akt (AktT308D/S473D, further referred to as AktDD) and analyzed neurochemically by immunocytochemistry against specific marker proteins. IUE of BRAFV600E/AktDD in mice resulted in tumors with the morphological features of human GGs. Our immunocytochemical analysis revealed a strong reduction of GABAARα1 immunoreactivity in the tumor compared to the PTME. In contrast, the extent of NMDAR1 immunoreactivity in the tumor appeared comparable to the PTME. Interestingly, tumor cells maintained the potential to express both receptors. Fittingly, the abundance of the presynaptic vesicular neurotransmitter transporters VGLUT1 and VGAT was also decreased in the tumor. Additionally, the fraction of parvalbumin and somatostatin non-neoplastic interneurons was reduced. In conclusion, changes in the levels of key proteins in neurotransmitter signaling suggest a loss of synapses and may thereby lead to neuronal network alterations in mouse GGs