Amyloid-β Oligomers Regulate ADAM10 Synaptic Localization Through Aberrant Plasticity Phenomena

A disintegrin and metalloproteinase 10 (ADAM10) is a synaptic enzyme that has been previously shown to limit amyloid-\u3b21-42 (A\u3b21-42) peptide formation in Alzheimer's disease (AD). Furthermore, ADAM10 participates to spine shaping through the cleavage of adhesion molecules and its activity is under the control of synaptic plasticity events. In particular, long-term depression (LTD) promotes ADAM10 synaptic localization triggering its forward trafficking to the synapse, while long-term potentiation elicits ADAM10 internalization. Here, we show that a short-term in vitro exposure to A\u3b21-42 oligomers, at a concentration capable of inducing synaptic depression and spine loss, triggers an increase in ADAM10 synaptic localization in hippocampal neuronal cultures. However, the A\u3b21-42 oligomers-induced synaptic depression does not foster ADAM10 delivery to the synapse, as the physiological LTD, but impairs ADAM10 endocytosis. Moreover, A\u3b21-42 oligomers-induced inhibition of ADAM10 internalization requires neuronal activity and the activation of the NMDA receptors. These data suggest that, at the synaptic level, A\u3b21-42 oligomers trigger an aberrant plasticity mechanism according to which A\u3b21-42 oligomers can downregulate A\u3b2 generation through the modulation of ADAM10 synaptic availability. Moreover, the increased activity of ADAM10 towards its synaptic substrates could also affect the structural plasticity phenomena. Overall, these data shed new lights on the strict and complex relationship existing between synaptic activity and the primary mechanisms of AD pathogenesis

Immune response to the recombinant herpes zoster vaccine in people living with HIV over 50 years of age compared to non-HIV age-/gender-matched controls (SHINGR’HIV): a multicenter, international, non-randomized clinical trial study protocol

Background The burden of herpes zoster (shingles) virus and associated complications, such as post-herpetic neuralgia, is higher in older adults and has a significant impact on quality of life. The incidence of herpes zoster and post-herpetic neuralgia is increased in people living with HIV (PLWH) compared to an age-matched general population, including PLWH on long-term antiretroviral therapy (ART) with no detectable viremia and normal CD4 counts. PLWH – even on effective ART may- exhibit sustained immune dysfunction, as well as defects in cells involved in the response to vaccines. In the context of herpes zoster, it is therefore important to assess the immune response to varicella zoster virus vaccination in older PLWH and to determine whether it significantly differs to that of HIV-uninfected healthy adults or younger PLWH. We aim at bridging these knowledge gaps by conducting a multicentric, international, non-randomised clinical study (SHINGR’HIV) with prospective data collection after vaccination with an adjuvant recombinant zoster vaccine (RZV) in two distinct populations: in PLWH on long-term ART (> 10 years) over 50 years of and age/gender matched controls. Methods We will recruit participants from two large established HIV cohorts in Switzerland and in France in addition to age-/gender-matched HIV-uninfected controls. Participants will receive two doses of RZV two months apart. In depth-evaluation of the humoral, cellular, and innate immune responses and safety profile of the RZV will be performed to address the combined effect of aging and potential immune deficiencies due to chronic HIV infection. The primary study outcome will compare the geometric mean titer (GMT) of gE-specific total IgG measured 1 month after the second dose of RZV between different age groups of PLWH and between PLWH and age-/gender-matched HIV-uninfected controls. Discussion The SHINGR’HIV trial will provide robust data on the immunogenicity and safety profile of RZV in older PLWH to support vaccination guidelines in this population. Trial registration ClinicalTrials.gov NCT05575830. Registered on 12 October 2022. Eu Clinical Trial Register (EUCT number 2023-504482-23-00)

Serum Total Tryptase Level Confirms Itself as a More Reliable Marker of Mast Cells Burden in Mast Cell Leukaemia (Aleukaemic Variant)

Mast cell leukemia (MCL) is a very rare form of systemic mastocytosis (SM) with a short median survival of 6 months. We describe a case of a 65-year-old woman with aleukaemic variant of MCL with a very high serum total tryptase level of 2255 μg/L at diagnosis, which occurred following an episode of hypotensive shock. She fulfilled the diagnostic criteria of SM, with a bone marrow smear infiltration of 50–60% of atypical mast cells (MCs). She tested negative for the KIT D816V mutation, without any sign of organ damage (no B- or C-findings) and only few mediator-related symptoms. She was treated with antihistamine alone and then with imatinib for the appearance of anemia. She maintained stable tryptase level and a very indolent clinical course for twenty-two months; then, she suddenly progressed to acute MCL with a serum tryptase level up to 12960 μg/L. The patient died due to haemorrhagic diathesis twenty-four months after diagnosis. This clinical case maybe represents an example of the chronic form of mast cell leukemia, described as unpredictable disease, in which the serum total tryptase level has confirmed itself as a reliable marker of mast cells burden regardless of the presence of other signs or symptoms

Linking NMDA Receptor Synaptic Retention to Synaptic Plasticity and Cognition

NMDA receptor (NMDAR) subunit composition plays a pivotal role in synaptic plasticity at excitatory synapses. Still, the mechanisms responsible for the synaptic retention of NMDARs following induction of plasticity need to be fully elucidated. Rabphilin3A (Rph3A) is involved in the stabilization of NMDARs at synapses through the formation of a complex with GluN2A and PSD-95. Here we used different protocols to induce synaptic plasticity in the presence or absence of agents modulating Rph3A function. The use of Forskolin/Rolipram/Picrotoxin cocktail to induce chemical LTP led to synaptic accumulation of Rph3A and formation of synaptic GluN2A/Rph3A complex. Notably, Rph3A silencing or use of peptides interfering with the GluN2A/Rph3A complex blocked LTP induction. Moreover, in vivo disruption of GluN2A/Rph3A complex led to a profound alteration of spatial memory. Overall, our results demonstrate a molecular mechanism needed for NMDAR stabilization at synapses after plasticity induction and to trigger downstream signaling events necessary for cognitive behavior

ADAM10 in Synaptic Physiology and Pathology

Generation of amyloid-\u3b2 peptide is at the beginning of a cascade that leads to Alzheimer's disease. Amyloid precursor protein (APP) as well as \u3b2- and \u3b3-secretases are the principal players involved in amyloid-\u3b2 (A\u3b2) production, while \u3b1-secretase cleavage on APP prevents A\u3b2 deposition. A disintegrin and metalloproteinase 10 (ADAM10) has been demonstrated to act as \u3b1-secretase in neurons. Objective: Although localization of ADAM10 in the synaptic membrane is the key for its shedding activity, currently, very little is known about the mechanisms that control the synaptic abundance of ADAM10. Results: Two established forms of long-term activity-dependent plasticity, i.e. long-term potentiation and long-term depression (LTD), differentially regulate the synaptic availability and activity of ADAM10. Long-term potentiation decreases ADAM10 surface levels and activity by promoting its endocytosis. This process is mediated by activity-regulated association of ADAM10 with the clathrin adaptor protein 2 (AP2) complex. Conversely, LTD fosters ADAM10 insertion in the membrane and stimulates its activity. Furthermore, ADAM10 interaction with synapse-associated protein 97 (SAP97) is necessary for LTD-induced ADAM10 trafficking and required for LTD maintenance and LTD-induced spine morphology changes. Conclusions: Regulated interaction of ADAM10 with SAP97 and AP2 discloses a novel physiological mechanism of ADAM10 activity regulation at the synapses. This phenomenon produces a situation whereby synaptically regulated ADAM10 activity is positioned to modulate synaptic functionin

Peptidi attivatori dell'enzima ADAM10 e relativi usi nel trattamento delle patologie caratterizzate da un aumento del peptide β-amiloide

The present intervention relates to new peptides that increase the activity of the enzyme ADAM10 by acting at various levels in the cascade of events that leads to the accumulation of the beta-amyloid peptide. Pharmaceutical compositions are also contemplated comprising activator peptides of the enzyme ADAM10 and the related uses in the medical field for the treatment and/or prevention of the pathologies wherein the increase or accumulation of the beta-amyloid peptide occurs, such as Alzheimer's Disease, head injury and post-traumatic stress disorder