Serotoninergic modulation of sensory transmission to brainstem reticulospinal cells

Sensory inputs are subjected to modulation by central neural networks involved in controlling movements. It has been shown that serotonin (5‐HT) modulates sensory transmission. This study examines in lampreys the effects of 5‐HT on sensory transmission to brainstem reticulospinal (RS) neurons and the distribution of 5‐HT cells that innervate RS cells. Cells were recorded intracellularly in the in vitro isolated brainstem of larval lampreys. Trigeminal nerve stimulation elicited disynaptic excitatory responses in RS neurons, and bath application of 5‐HT reduced the response amplitude with maximum effect at 10 μm. Local ejection of 5‐HT either onto the RS cells or onto the relay cells decreased sensory‐evoked excitatory postsynaptic potentials (EPSPs) in RS cells. The monosynaptic EPSPs elicited from stimulation of the relay cells were also reduced by 5‐HT. The reduction was maintained after blocking either N‐methyl‐d‐aspartate (NMDA) or α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionic acid (AMPA) receptors. The local ejection of glutamate over RS cells elicited excitatory responses that were only slightly depressed by 5‐HT. In addition, 5‐HT increased the threshold for eliciting sustained depolarizations in response to trigeminal nerve stimulation but did not prevent them. Combined 5‐HT immunofluorescence with axonal tracing revealed that the 5‐HT innervation of RS neurons of the middle rhombencephalic reticular nucleus comes mainly from neurons in the isthmic region, but also from neurons located in the pretectum and caudal rhombencephalon. Our results indicate that 5‐HT modulates sensory transmission to lamprey brainstem RS cells

Gβγ and the C Terminus of SNAP-25 Are Necessary for Long-Term Depression of Transmitter Release

Short-term presynaptic inhibition mediated by G protein-coupled receptors involves a direct interaction between G proteins and the vesicle release machinery. Recent studies implicate the C terminus of the vesicle-associated protein SNAP-25 as a molecular binding target of Gβγ that transiently reduces vesicular release. However, it is not known whether SNAP-25 is a target for molecular modifications expressing long-term changes in transmitter release probability.This study utilized two-photon laser scanning microscopy for real-time imaging of action potential-evoked [Ca(2+)] increases, in single Schaffer collateral presynaptic release sites in in vitro hippocampal slices, plus simultaneous recording of Schaffer collateral-evoked synaptic potentials. We used electroporation to infuse small peptides through CA3 cell bodies into presynaptic Schaffer collateral terminals to selectively study the presynaptic effect of scavenging the G-protein Gβγ. We demonstrate here that the C terminus of SNAP-25 is necessary for expression of LTD, but not long-term potentiation (LTP), of synaptic strength. Using type A botulinum toxin (BoNT/A) to enzymatically cleave the 9 amino acid C-terminus of SNAP-25 eliminated the ability of low frequency synaptic stimulation to induce LTD, but not LTP, even if release probability was restored to pre-BoNT/A levels by elevating extracellular [Ca(2+)]. Presynaptic electroporation infusion of the 14-amino acid C-terminus of SNAP-25 (Ct-SNAP-25), to scavenge Gβγ, reduced both the transient presynaptic inhibition produced by the group II metabotropic glutamate receptor stimulation, and LTD. Furthermore, presynaptic infusion of mSIRK, a second, structurally distinct Gβγ scavenging peptide, also blocked the induction of LTD. While Gβγ binds directly to and inhibit voltage-dependent Ca(2+) channels, imaging of presynaptic [Ca(2+)] with Mg-Green revealed that low-frequency stimulation only transiently reduced presynaptic Ca(2+) influx, an effect not altered by infusion of Ct-SNAP-25.The C-terminus of SNAP-25, which links synaptotagmin I to the SNARE complex, is a binding target for Gβγ necessary for both transient transmitter-mediated presynaptic inhibition, and the induction of presynaptic LTD

G protein-coupled receptors inhibit neurotransmitter release by modifying vesicle fusion properties.

G protein-coupled receptors inhibit neurotransmitter release by modifying vesicle fusion properties

Switching to risankizumab from ustekinumab or adalimumab in plaque psoriasis patients improves PASI and DLQI outcomes for sub-optimal responders

Background Psoriasis is often treated with biologic therapies. While many patients see improvement in their symptoms with treatment, some achieve only partial success. Objective and Methods In this post-hoc analysis we assess Psoriasis Area Severity Index (PASI) and Dermatology Life Quality Index (DLQI) results from patients who switched to RZB due to suboptimal results that originally received ADA (N = 53, IMMvent NCT02694523) or UST (N = 172, UltIMMa-1 [NCT02684370], UltIMMa-2 [NCT02684357]). Results For patients originally treated with ADA, after three doses of RZB, 83.3% of PASI 50 to <75 patients improved to PASI ≥75 and for PASI 75 to <90 patients, 77.1% improved to PASI ≥90. For patients originally treated with UST, after 7 doses of RZB, 86.8% of PASI <75 patients improved to PASI ≥75 and 75.5% of PASI 75 to ≤90 patients improved to PASI ≥90. No patients demonstrated worsening from their initial PASI group after switching. There were no significant safety events associated with switching patients to RZB without a washout period. Conclusion For patients with an inadequate or incomplete response to UST or ADA, switching to RZB improved PASI scores and DLQI for patients with moderate to severe plaque psoriasis with no significant safety risks

Efficacy of risankizumab in patients with moderate-to-severe plaque psoriasis by baseline demographics, disease characteristics and prior biologic therapy: an integrated analysis of the phase III UltIMMa-1 and UltIMMa-2 studies.

BACKGROUND: Risankizumab is a humanized IgG monoclonal antibody that selectively inhibits interleukin-23 through binding the p19 subunit. In Phase 3 trials, risankizumab demonstrated superior efficacy compared with adalimumab and ustekinumab in patients with moderate-to-severe plaque psoriasis. Here, we evaluated the impact of baseline characteristics on efficacy of risankizumab compared with ustekinumab in patients with moderate-to-severe plaque psoriasis. METHODS: This analysis included all patients initially randomized to risankizumab or ustekinumab from the replicate, double-blinded, randomized, placebo-controlled phase 3 trials, UltIMMa-1 (NCT02684370) and UltIMMa-2 (NCT02684357). Patients received either risankizumab (150 mg) or ustekinumab (weight-based; 45 or 90 mg per label) at weeks 0, 4, 16, 28 and 40. Efficacy was assessed as the proportion of patients achieving ≥90% improvement in Psoriasis Area and Severity Index (PASI 90) at weeks 16 and 52 by baseline patient demographics, disease characteristics and prior biologic exposure. Mean per cent improvement in PASI was calculated by body weight and body mass index at week 52. Missing efficacy data were imputed as non-responders for categorical variables and last observation carried forward for continuous variables. Logistic regression analyses assessed for interactions between treatment and five independent variables (age, sex, weight, baseline PASI score and presence of psoriatic arthritis) at both weeks 16 and 52. RESULTS: Baseline patient demographics, disease characteristics and prior biologic exposure were similar between patients randomized to risankizumab (n = 598) and ustekinumab (n = 199). At weeks 16 and 52, risankizumab demonstrated superior efficacy compared with ustekinumab across these patient characteristics (P < 0.01). Logistic regression analyses demonstrated that risankizumab was superior to ustekinumab at weeks 16 and 52 in all models tested (P < 0.0001 for all). CONCLUSIONS: Risankizumab demonstrated consistent and superior efficacy compared with ustekinumab regardless of patient demographics, disease characteristics or prior biologic exposure

Real-world dose escalation of biologics for moderate-to-severe psoriasis in the United States

Aim To compare real-world dose escalation of risankizumab with other US Food and Drug Administration (FDA)-approved biologic treatments for management of moderate-to-severe psoriasis (PsO) in the United States. Methods The Merative® MarketScan® Research Database was used to identify adults with ≥2 medical claims for PsO, ≥3 claims of the index biologic medication in the maintenance period, and ≥6 months continuous enrollment pre-induction and ≥6 months after initiation of the maintenance period. Dose escalation was defined as ≥2 dosing intervals where the average daily dose was ≥30% higher than the expected daily dose (per FDA-approved dosing). Comparisons between risankizumab and other cohorts were made using chi-square tests and logistic regression models. Results At the 30% threshold, the percentage of patients with dose escalation in the full maintenance period was significantly lower with risankizumab (2.0%) compared with other drug classes (tumor necrosis factor, interleukin (IL)-12/23, IL-17, or other IL-23 inhibitors: 17.6%, 10.0%, 18.3%, or 7.1%, respectively; p < 0.0001 for each) and individual biologics (adalimumab, ustekinumab, secukinumab, ixekizumab, and guselkumab; 17.9%, 10.0%, 15.7%, 18.0%, and 7.2%, respectively; p < 0.0001). Conclusion A significantly lower proportion of risankizumab-treated patients with PsO had dose escalations compared with patients treated with other biologics

Impact of psoriasis disease severity and special area involvement on patient-reported outcomes in the real world: an analysis from the CorEvitas psoriasis registry

AbstractBackground The impact of psoriasis in special areas (i.e., scalp, nails, palms, soles, genitals) on patient physical functioning, health-related quality of life (HRQoL), and work abilities has not been fully characterized. We assessed associations between disease severity and special area involvement in psoriasis symptoms, HRQoL, and work/activity impairment.Methods Patients with psoriasis from the CorEvitas Psoriasis Registry who initiated systemic treatment between 04/2015–06/2020 were included. Outcomes were change from baseline in psoriasis symptoms, Dermatology Life Quality Index (DLQI), and work/activity impairment at 6 months stratified by baseline disease severity and special area involvement.Results Among 2620 patients, increasing disease severity was associated with worsening patient-reported outcomes. Patients with (46.0%; N = 1205) versus without (54.0%; N = 1415) psoriasis in special areas reported greater HRQoL and work/activity impairment. Over 6 months, patients with unchanged or worsening disease severity had reduced HRQoL and increased symptom severity; incremental increases in patient HRQoL and decreases in symptom severity were associated with improved disease severity.Conclusions Higher disease severity and special area involvement was associated with worse outcomes and impaired work abilities. These data highlight the significant impact that adequate treatment of severe psoriasis and/or special area involvement may have on patient HRQoL and function

Coordination of synaptic adhesion with dendritic spine remodeling by AF-6 and kalirin-7

Remodeling of central excitatory synapses is crucial for synapse maturation, plasticity, and contributes to neurodevelopmental and psychiatric disorders. Remodeling of dendritic spines and the associated synapses, has been postulated to require the coordination of adhesion with spine morphology and stability; however, the molecular mechanisms that functionally link adhesion molecules with regulators of dendritic spine morphology are largely unknown. Here we report that spine size and N-cadherin content are tightly coordinated. In rat mature cortical pyramidal neurons, N-cadherin-dependent adhesion modulates the morphology of existing spines by recruiting the Rac1 guanine-nucleotide exchange factor kalirin-7 to synapses through the scaffolding protein AF-6/afadin. In pyramidal neurons, N-cadherin, AF-6, and kalirin-7 colocalize at synapses and participate in the same multiprotein complexes. N-cadherin clustering promotes the reciprocal interaction and recruitment of N-cadherin, AF-6, and kalirin-7, increasing the content of Rac1 and in spines and PAK phosphorylation. N-cadherin-dependent spine enlargement requires AF-6 and kalirin-7 function. Conversely, disruption of N-cadherin leads to thin, long spines, with reduced Rac1 contact, caused by uncoupling of N-cadherin, AF-6, and kalirin-7 from each other. By dynamically linking N-cadherin with a regulator of spine plasticity, this pathway allows synaptic adhesion molecules to rapidly coordinate spine remodeling associated with synapse maturation and plasticity. This study hence identifies a novel mechanism whereby cadherins, a major class of synaptic adhesion molecules, signal to the actin cytoskeleton to control the morphology of dendritic spines, and outlines a mechanism that underlies the coordination of synaptic adhesion with spine morphology