Humanitarian Aeromedical Retrieval using a Long-Range Commercial Aircraft: A Field Report

This field report presents the planning and execution of a large-scale aeromedical refugee retrieval operation amid the on-going Russia-Ukraine crisis. The retrieval was coordinated by the Italian Department of Civil Protection and led by the Centrale Remota Operazioni Soccorso Sanitario (CROSS), a governmental facility overseeing medical assistance. An Airbus A320 was chosen for its capacity of 165 passengers, with one emergency stretcher maintaining maximum seating. The aircraft was equipped with an Advanced Life Support kit, and specific considerations for medical equipment compliance were made. Special cases, including patients with on-going chemotherapy and end-stage kidney disease, underwent fit-to-fly screening. The boarding process in Lublin, Poland involved triage and arrangements for passengers with gastroenteric symptoms. Notably, 22 passengers with recent episodes of illness were isolated. The successful operation, demonstrating the viability of evacuating vulnerable individuals via commercial airlines, underscores the importance of precise planning and coordination in crisis situations.

CAMSAPs and nucleation-promoting factors control microtubule release from γ-TuRC

γ-Tubulin ring complex (γ-TuRC) is the major microtubule-nucleating factor. After nucleation, microtubules can be released from γ-TuRC and stabilized by other proteins, such as CAMSAPs, but the biochemical cross-talk between minus-end regulation pathways is poorly understood. Here we reconstituted this process in vitro using purified components. We found that all CAMSAPs could bind to the minus ends of γ-TuRC-attached microtubules. CAMSAP2 and CAMSAP3, which decorate and stabilize growing minus ends but not the minus-end tracking protein CAMSAP1, induced microtubule release from γ-TuRC. CDK5RAP2, a γ-TuRC-interactor, and CLASP2, a regulator of microtubule growth, strongly stimulated γ-TuRC-dependent microtubule nucleation, but only CDK5RAP2 suppressed CAMSAP binding to γ-TuRC-anchored minus ends and their release. CDK5RAP2 also improved selectivity of γ-tubulin-containing complexes for 13- rather than 14-protofilament microtubules in microtubule-capping assays. Knockout and overexpression experiments in cells showed that CDK5RAP2 inhibits the formation of CAMSAP2-bound microtubules detached from the microtubule-organizing centre. We conclude that CAMSAPs can release newly nucleated microtubules from γ-TuRC, whereas nucleation-promoting factors can differentially regulate this process.

Prehospital Mass Casualty Incident Response to a Fire in a Nursing Home in Milan, Italy: Actions Taken and Shortcomings

On July 7, 2023, at 1:21 am, a fire was declared in a retirement home in Milan, Italy. The number of casualties (n = 87) according to the Simple Triage and Rapid Treatment (START) triage system was categorized as 65 green, 14 yellow, 2 red, and 6 black; 75% were women, and the mean age was 85.1 years (± 9). Most patients were unable to walk. A total of 30 basic life support (BLS) ambulances, 3 advanced cardiac life support (ACLS) teams on fast cars, 2 buses, and 1 coordination team were deployed. A scoop and run approach was adopted with patients being transported to 15 health care facilities. The event was terminated at 5:43 am. Though the local mass casualty incident (MCI) response plan was correctly applied, the evacuation of the building was difficult due to the age and comorbidities of the patients. START failed to correctly identify patients categorized as minor. Communication problems arose on site that led to the late evacuation of critical patients.

Development and Validation of a New Tool to Improve the Accuracy of the Hospital Mass-Casualty Incident Response Plan Activation: The PEMAAF Score

INTRODUCTION

Effective response to a mass-casualty incident (MCI) entails the activation of hospital MCI plans. Unfortunately, there are no tools available in the literature to support hospital responders in predicting the proper level of MCI plan activation. This manuscript describes the scientific-based approach used to develop, test, and validate the PEMAAF score (Proximity, Event, Multitude, Overcrowding, Temporary Ward Reduction Capacity, Time Shift Slot [Prossimità, Evento, Moltitudine, Affollamento, Accorpamento, Fascia Oraria], a tool able to predict the required level of hospital MCI plan activation and to facilitate a coordinated activation of a multi-hospital network.

METHODS

Three study phases were performed within the Metropolitan City of Milan, Italy: (1) retrospective analysis of past MCI after action reports (AARs); (2) PEMAAF score development; and (3) PEMAAF score validation. The validation phase entailed a multi-step process including two retrospective analyses of past MCIs using the score, a focus group discussion (FGD), and a prospective simulation-based study. Sensitivity and specificity of the score were analyzed using a regression model, Spearman's Rho test, and receiver operating characteristic/ROC analysis curves.

RESULTS

Results of the retrospective analysis and FGD were used to refine the PEMAAF score, which included six items-Proximity, Event, Multitude, Emergency Department (ED) Overcrowding, Temporary Ward Reduction Capacity, and Time Shift Slot-allowing for the identification of three priority levels (score of 5-6: green alert; score of 7-9: yellow alert; and score of 10-12: red alert). When prospectively analyzed, the PEMAAF score determined most frequent hospital MCI plan activation (>10) during night and holiday shifts, with a score of 11 being associated with a higher sensitivity system and a score of 12 with higher specificity.

CONCLUSIONS

The PEMAAF score allowed for a balanced and adequately distributed response in case of MCI, prompting hospital MCI plan activation according to real needs, taking into consideration the whole hospital response network.

Severe Acute Respiratory Syndrome Coronavirus 2 and Medical Evacuation in Lombardy: Lessons Learned from an Unprecedented Pandemic

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerging infectious disease pandemic developed in Lombardy (northern Italy) during the last week of February 2020 with a progressive increase of patients presenting with serious clinical findings. Despite the efforts of the Central Italian Government, regional resources were rapidly at capacity. The solution was to plan the medical evacuation (MEDEVAC) of 119 critically ill patients (median age 61 years) to in-patient intensive care units in other Italian regions (77) and Germany (42). Once surviving patients were deemed suitable, the repatriation process concluded the assignment. The aim of this report is to underline the importance of a rapid organization and coordination process between different nodes of an effective national and international network during an emerging infectious disease outbreak and draw lessons learned from similar published reports.

How the Italian Formula 1 Grand Prix 2022 Mass Gathering Event Compares to the Arbon Model: A Descriptive Study

OBJECTIVE

To describe the health-care resources implemented during the Italian Formula 1 Grand Prix (F1GP) and to calculate the patient presentation rate (PPR) based on both real data and a prediction model.

METHODS

Observational and descriptive study conducted from September 9 to September 11, 2022, during the Italian F1GP hosted in Monza (Italy). Maurer's formula was applied to decide the number and type of health resources to be allocated. Patient presentation rate (PPR) was computed based on real data (PPR_real) and based on the Arbon formula (PPR_est).

RESULTS

Of 336,000 attendees, n = 263 requested medical assistance with most of them receiving treatment at the advanced medical post, and n = 16 needing transport to the hospital. The PPR_real was 51 for Friday, 78 for Saturday, 134 for Sunday, and 263 when considering the whole event as a single event. The PPR_est resulted in 85 for Friday, 93 for Saturday, 97 for Sunday, and 221 for the total population.

CONCLUSIONS

A careful organization of health-care resources could mitigate the impact of the Italian F1GP on local hospital facilities. The Arbon formula is an acceptable model to predict and estimate the number of patients requesting medical assistance, but further investigation needs to be conducted to implement the model and tailor it to broader categories of MGE.

Targeted delivery of tumor necrosis factor in combination with CCNU induces a T cell-dependent regression of glioblastoma

Glioblastoma is the most aggressive primary brain tumor with an unmet need for more effective therapies. Here, we investigated combination therapies based on L19TNF, an antibody-cytokine fusion protein based on tumor necrosis factor that selectively localizes to cancer neovasculature. Using immunocompetent orthotopic glioma mouse models, we identified strong anti-glioma activity of L19TNF in combination with the alkylating agent CCNU, which cured the majority of tumor-bearing mice, whereas monotherapies only had limited efficacy. In situ and ex vivo immunophenotypic and molecular profiling in the mouse models revealed that L19TNF and CCNU induced tumor DNA damage and treatment-associated tumor necrosis. In addition, this combination also up-regulated tumor endothelial cell adhesion molecules, promoted the infiltration of immune cells into the tumor, induced immunostimulatory pathways, and decreased immunosuppression pathways. MHC immunopeptidomics demonstrated that L19TNF and CCNU increased antigen presentation on MHC class I molecules. The antitumor activity was T cell dependent and completely abrogated in immunodeficient mouse models. On the basis of these encouraging results, we translated this treatment combination to patients with glioblastoma. The clinical translation is ongoing but already shows objective responses in three of five patients in the first recurrent glioblastoma patient cohort treated with L19TNF in combination with CCNU (NCT04573192).

Fibroblast Activation Protein Triggers Release of Drug Payload from Non-internalizing Small Molecule Drug Conjugates in Solid Tumors

PURPOSE

Small molecule drug conjugates (SMDC) are modular anticancer prodrugs that include a tumor-targeting small organic ligand, a cleavable linker, and a potent cytotoxic agent. Most of the SMDC products that have been developed for clinical applications target internalizing tumor-associated antigens on the surface of tumor cells. We have recently described a novel non-internalizing small organic ligand (named OncoFAP) of fibroblast activation protein (FAP), a tumor-associated antigen highly expressed in the stroma of most solid human malignancies.

EXPERIMENTAL DESIGN

In this article, we describe a new series of OncoFAP-Drug derivatives based on monomethyl auristatin E (MMAE; a potent cytotoxic tubulin poison) and dipeptide linkers that are selectively cleaved by FAP in the tumor microenvironment.

RESULTS

The tumor-targeting potential of OncoFAP was confirmed in patients with cancer using nuclear medicine procedures. We used mass spectrometry methodologies to quantify the amount of prodrug delivered to tumors and normal organs, as well as the efficiency of the drug release process. Linkers previously exploited for anticancer drug conjugates were used as benchmark. We identified OncoFAP-Gly-Pro-MMAE as the best performing SMDC, which has now been prioritized for further clinical development. OncoFAP-Gly-Pro-MMAE selectively delivered more than 10% injected dose per gram of MMAE to FAP-positive tumors, with a tumor-to-kidney ratio of 16:1 at 24 hours post-injection.

CONCLUSIONS

The FAP-specific drug conjugates described in this article promise to be efficacious for the targeting of human malignancies. The extracellular release of potent anticancer payloads mediates durable complete remission in difficult-to-treat animal models of cancer.

CTIM-22. THE COMBINATION OF LOMUSTINE AND THE IMMUNOCYTOKINE L19TNF IS A PROMISING TREATMENT FOR RECURRENT GLIOBLASTOMA

Glioblastoma is the most aggressive primary brain tumor and adults and poorly immunogenic. Treatment options for recurrent glioblastoma after standard of care chemoradiation are limited Several immunotherapeutic strategies including peptide vaccination and immune checkpoint inhibition have so far failed to improve survival and except from potentially regorafenib, no other agent has demonstrated superior activity to lomustine. Therefore, there is an urgent need for more effective treatment strategies for recurrent glioblastoma. Here, we investigate a new treatment combination based on the alkylating chemotherapy lomustine and the tumor-stroma targeting antibody-cytokine fusion protein L19TNF in preclinical glioma models and patients with recurrent glioblastoma. The combination treatment with lomustine and L19TNF demonstrated strong synergistic anti-tumor activity in several immunocompetent orthotopic glioma models curing the majority of tumor-bearing mice, whereas other mono- or combination therapies for example with anti-PD1 had only limited anti-glioma activity. Investigations of the mechanism of action revealed that lomustine plus L19TNF led to intratumoral necrosis, DNA damage and triggered a strong local anti-tumor immune response with increased MHC-I expression, presentation of neoepitopes and increased abundance of tumor-infiltrating lymphoid cells. In the first patients treated within a phase I/II clinical trial (NCT04573192), the treatment was well tolerated, and durable objective tumor responses and disease stabilizations could be observed also in patients with an unmethylated MGMT promoter.

OS08.7.A Lomustine and the immunocytokine L19TNF are a promising treatment combination for recurrent glioblastoma

Background

Treatment options for recurrent glioblastoma are limited and with the possible exception of regorafenib, no agent has demonstrated superior activity to lomustine. Therefore, there is an urgent need for more effective treatment strategies for recurrent glioblastoma. Here, we investigated different treatment combinations based on the tumor-stroma targeting antibody-cytokine fusion protein L19TNF in preclinical glioma models and translated the most effective treatment combination to patients with recurrent glioblastoma.

Material and Methods

Orthotopic immunocompetent mouse glioma models were used to study the anti-glioma activity of L19TNF in combination with anti-PD1, bevacizumab or lomustine. Tumor growth was monitored by MRI. Flow cytometry and microscopy were used to characterize tumor-infiltrating-immune cells. MHC immunoaffinity purification and mass spectrometry were used to characterize the MHC immunopeptidome. Genetic mouse models were used to study immune-dependent effects. Subsequently, we translated the most efficient treatment combination to patients with recurrent glioblastoma within a phase I/II clinical trial (NCT04573192).

Results

The combination of L19TNF and lomustine demonstrated strong synergistic anti-tumor activity in two immunocompetent orthotopic glioma models and cured a majority of tumor-bearing mice. In contrast, combinations with anti-PD-1 or bevacizumab had only limited anti-glioma activity. Furthermore, compared to the monotherapies, the combination of L19TNF and lomustine led to the strongest increase in tumor-infiltrating lymphoid cells as demonstrated by flow cytometry and microsopy and to the highest number of peptides presented in the context of MHC-I. The treatment effect was abrograted in different genetic immunodeficient mouse models. The treatment combination of L19TNF and lomustine was well tolerated in the first patients treated within a phase I/II clinical trial and we observed partial tumor responses also in patients with an unmethylated MGMT promoter.

Conclusion

The combination of L19TNF and lomustine demonstrated promising anti-glioma activity and patients are currently recruited within a phase I/II clinical trial for patients with recurrent glioblastoma.

The centriolar satellite protein Cfap53 facilitates formation of the zygotic microtubule organizing center in the zebrafish embryo

In embryos of most animal species, the zygotic centrosome is assembled by the centriole derived from the sperm cell and pericentriolar proteins present in the oocyte. This zygotic centrosome acts as a microtubule organizing center (MTOC) to assemble the sperm aster and mitotic spindle. As MTOC formation has been studied mainly in adult cells, very little is known about the formation of the zygotic MTOC. Here, we show that zebrafish (Danio rerio) embryos lacking either maternal or paternal Cfap53, a centriolar satellite protein, arrest during the first cell cycle. Although Cfap53 is dispensable for sperm aster function, it aids proper formation of the mitotic spindle. During cell division, Cfap53 colocalizes with γ-tubulin and with other centrosomal and centriolar satellite proteins at the MTOC. Furthermore, we find that γ-tubulin localization at the MTOC is impaired in the absence of Cfap53. Based on these results, we propose a model in which Cfap53 deposited in the oocyte and the sperm participates in the organization of the zygotic MTOC to allow mitotic spindle formation.

Mass Spectrometry-Based Method for the Determination of the Biodistribution of Tumor-Targeting Small Molecule-Metal Conjugates

Nuclear medicine plays a key role in modern diagnosis and cancer therapy. The development of tumor-targeting radionuclide conjugates (also named small molecule-radio conjugates (SMRCs)) represents a significant improvement over the clinical use of metabolic radiotracers (e.g., [¹⁸F]-fluorodeoxyglucose) for imaging and over the application of biocidal external beam radiations for therapy. During the discovery of SMRCs, molecular candidates must be carefully evaluated typically by performing biodistribution assays in preclinical tumor models. Quantification methodologies based on radioactive counts are typically demanding due to safety concerns, availability of radioactive materials, and infrastructures. In this article, we report the development of a mass spectrometry (MS)-based method for the detection and quantification of small molecule-metal conjugates (SMMCs) as cold surrogates of SMRCs. We applied this methodology for the evaluation of the biodistribution of a particular class of tumor-targeting drug candidates based on ^natLu, ^natGa, and ^natF and directed against fibroblast activation protein (FAP). The reliability of the liquid chromatography-MS (LC-MS) analysis was validated by a direct comparison of MS-based and radioactivity-based biodistribution data. The results show that MS biodistribution of stable isotope metal conjugates is an orthogonal tool for the preclinical characterization of different classes of radiopharmaceuticals.

Abstract LB522: Fibroblast activation protein triggers the release of drug payload from non-internalizing small molecule-drug conjugates in solid tumors

Small Molecule-Drug Conjugates (SMDCs) are modular anti-cancer pro-drugs that include a tumor-targeting small ligand, a cleavable linker and a potent cytotoxic agent. SMDC products that have been developed for clinical applications are targeting internalizing tumor-associated antigens expressed on the surface of tumor cells. We have recently developed a novel non-internalizing small organic ligand (named OncoFAP) of Fibroblast Activation Protein (FAP), a tumor-associated antigen highly expressed in the stroma of most of solid human malignancies. The tumor targeting performance of OncoFAP has been validated by nuclear medicine studies in patients with various solid tumors. In a previous study, we showed that OncoFAP can be used to produce non-internalizing SMDCs that are effective and well tolerated. Here, we describe a new series of OncoFAP-Drug derivatives based on the MMAE tubulin poison and dipeptide linkers that are selectively cleaved by FAP in the tumor microenvironment. We benchmarked the new SMDCs against OncoFAP-MMAE conjugates displaying linker modules which are widely used in approved and clinical stage Antibody-Drug Conjugates, including structures cleaved by Cathepsin B and by reducing agents. We selected OncoFAP-GlyPro-MMAE as the most efficacious and safe SMDC for further clinical development after quantitatively analyzing the biodistribution of MMAE released by OncoFAP-MMAE conjugates. OncoFAP-GlyPro-MMAE selectively delivers high amounts of MMAE at the site of disease, with a tumor-to-kidney ratio of 7-to-1 and of 16-to-1 at 6- and 24-hours post-injection, respectively. Our molecules based on the OncoFAP tumor-targeting ligand and FAP-cleavable linkers promise to be safe and effective against most of human malignancies.

Citation Format: Aureliano Zana, Andrea Galbiati, Ettore Gilardoni, Jacopo Millul, Theo Sturm, Riccardo Stucchi, Matilde Bocci, Abdullah Elsayed, Lisa Nadal, Martina Cirillo, Dario Neri, Samuele Cazzamalli. Fibroblast activation protein triggers the release of drug payload from non-internalizing small molecule-drug conjugates in solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB522.

WDR47 protects neuronal microtubule minus ends from katanin-mediated severing

Axons and dendrites are long extensions of neurons that contain arrays of noncentrosomal microtubules. Calmodulin-regulated spectrin-associated proteins (CAMSAPs) bind to and stabilize free microtubule minus ends and are critical for proper neuronal development and function. Previous studies have shown that the microtubule-severing ATPase katanin interacts with CAMSAPs and limits the length of CAMSAP-decorated microtubule stretches. However, how CAMSAP and microtubule minus end dynamics are regulated in neurons is poorly understood. Here, we show that the neuron-enriched protein WDR47 interacts with CAMSAPs and is critical for axon and dendrite development. We find that WDR47 accumulates at CAMSAP2-decorated microtubules, is essential for maintaining CAMSAP2 stretches, and protects minus ends from katanin-mediated severing. We propose a model where WDR47 protects CAMSAP2 at microtubule minus ends from katanin activity to ensure proper stabilization of the neuronal microtubule network.

BBLN-1 is essential for intermediate filament organization and apical membrane morphology

Epithelial tubes are essential components of metazoan organ systems that control the flow of fluids and the exchange of materials between body compartments and the outside environment. The size and shape of the central lumen confer important characteristics to tubular organs and need to be carefully controlled. Here, we identify the small coiled-coil protein BBLN-1 as a regulator of lumen morphology in the C. elegans intestine. Loss of BBLN-1 causes the formation of bubble-shaped invaginations of the apical membrane into the cytoplasm of intestinal cells and abnormal aggregation of the subapical intermediate filament (IF) network. BBLN-1 interacts with IF proteins and localizes to the IF network in an IF-dependent manner. The appearance of invaginations is a result of the abnormal IF aggregation, indicating a direct role for the IF network in maintaining lumen homeostasis. Finally, we identify bublin (BBLN) as the mammalian ortholog of BBLN-1. When expressed in the C. elegans intestine, BBLN recapitulates the localization pattern of BBLN-1 and can compensate for the loss of BBLN-1 in early larvae. In mouse intestinal organoids, BBLN localizes subapically, together with the IF protein keratin 8. Our results therefore may have implications for understanding the role of IFs in regulating epithelial tube morphology in mammals.

Centrosome-mediated microtubule remodeling during axon formation in human iPSC-derived neurons

Axon formation critically relies on local microtubule remodeling and marks the first step in establishing neuronal polarity. However, the function of the microtubule‐organizing centrosomes during the onset of axon formation is still under debate. Here, we demonstrate that centrosomes play an essential role in controlling axon formation in human‐induced pluripotent stem cell (iPSC)‐derived neurons. Depleting centrioles, the core components of centrosomes, in unpolarized human neuronal stem cells results in various axon developmental defects at later stages, including immature action potential firing, mislocalization of axonal microtubule‐associated Trim46 proteins, suppressed expression of growth cone proteins, and affected growth cone morphologies. Live‐cell imaging of microtubules reveals that centriole loss impairs axonal microtubule reorganization toward the unique parallel plus‐end out microtubule bundles during early development. We propose that centrosomes mediate microtubule remodeling during early axon development in human iPSC‐derived neurons, thereby laying the foundation for further axon development and function.

Combined kinesin-1 and kinesin-3 activity drives axonal trafficking of TrkB receptors in Rab6 carriers

Neurons depend on proper localization of neurotrophic receptors in their distal processes for their function. The Trk family of neurotrophin receptors controls neuronal survival, differentiation, and remodeling and are well known to function as retrograde signal carriers transported from the distal axon toward the cell body. However, the mechanism driving anterograde trafficking of Trk receptors into the axon is not well established. We used microfluidic compartmental devices and inducible secretion assay to systematically investigate the retrograde and anterograde trafficking routes of TrkB receptor along the axon in rat hippocampal neurons. We show that newly synthesized TrkB receptors traffic through the secretory pathway and are directly delivered into axon. We found that these TrkB carriers associate and are regulated by Rab6. Furthermore, the combined activity of kinesin-1 and kinesin-3 is needed for the formation of axon-bound TrkB secretory carriers and their effective entry and processive anterograde transport beyond the proximal axon.

Rapid reorganization of the Milan metropolitan public safety answering point operations during the initial phase of the COVID-19 outbreak in Italy

Objective

To quantify how the first public announcement of confirmed coronavirus disease 2019 (COVID-19) in Italy affected a metropolitan region's emergency medical services (EMS) call volume and how rapid introduction of alternative procedures at the public safety answering point (PSAP) managed system resources.

Methods

PSAP processes were modified over several days including (1) referral of non-ill callers to public health information call centers; (2) algorithms for detection, isolation, or hospitalization of suspected COVID-19 patients; and (3) specialized medical teams sent to the PSAP for triage and case management, including ambulance dispatches or alternative dispositions. Call volumes, ambulance dispatches, and response intervals for the 2 weeks after announcement were compared to 2017-2019 data and the week before.

Results

For 2 weeks following outbreak announcement, the primary-level PSAP (police/fire/EMS) averaged 56% more daily calls compared to prior years and recorded 9281 (106% increase) on Day 4, averaging ∼400/hour. The secondary-level (EMS) PSAP recorded an analogous 63% increase with 3863 calls (∼161/hour; 264% increase) on Day 3. The COVID-19 response team processed the more complex cases (n = 5361), averaging 432 ± 110 daily (∼one-fifth of EMS calls). Although community COVID-19 cases increased exponentially, ambulance response intervals and dispatches (averaging 1120 ± 46 daily) were successfully contained, particularly compared with the week before (1174 ± 40; P = 0.02).

Conclusion

With sudden escalating EMS call volumes, rapid reorganization of dispatch operations using tailored algorithms and specially assigned personnel can protect EMS system resources by optimizing patient dispositions, controlling ambulance allocations and mitigating hospital impact. Prudent population-based disaster planning should strongly consider pre-establishing similar highly coordinated medical taskforce contingencies.

Quantitative mapping of transcriptome and proteome dynamics during polarization of human iPSC-derived neurons

The differentiation of neuronal stem cells into polarized neurons is a well-coordinated process which has mostly been studied in classical non-human model systems, but to what extent these findings are recapitulated in human neurons remains unclear. To study neuronal polarization in human neurons, we cultured hiPSC-derived neurons, characterized early developmental stages, measured electrophysiological responses, and systematically profiled transcriptomic and proteomic dynamics during these steps. The neuron transcriptome and proteome shows extensive remodeling, with differential expression profiles of ~1100 transcripts and ~2200 proteins during neuronal differentiation and polarization. We also identified a distinct axon developmental stage marked by the relocation of axon initial segment proteins and increased microtubule remodeling from the distal (stage 3a) to the proximal (stage 3b) axon. This developmental transition coincides with action potential maturation. Our comprehensive characterization and quantitative map of transcriptome and proteome dynamics provides a solid framework for studying polarization in human neurons.

Cortical anchoring of the microtubule cytoskeleton is essential for neuron polarity

The development of a polarized neuron relies on the selective transport of proteins to axons and dendrites. Although it is well known that the microtubule cytoskeleton has a central role in establishing neuronal polarity, how its specific organization is established and maintained is poorly understood. Using the in vivo model system Caenorhabditis elegans, we found that the highly conserved UNC-119 protein provides a link between the membrane-associated Ankyrin (UNC-44) and the microtubule-associated CRMP (UNC-33). Together they form a periodic membrane-associated complex that anchors axonal and dendritic microtubule bundles to the cortex. This anchoring is critical to maintain microtubule organization by opposing kinesin-1 powered microtubule sliding. Disturbing this molecular complex alters neuronal polarity and causes strong developmental defects of the nervous system leading to severely paralyzed animals.

The HAUS Complex Is a Key Regulator of Non-centrosomal Microtubule Organization during Neuronal Development

Neuron morphology and function are highly dependent on proper organization of the cytoskeleton. In neurons, the centrosome is inactivated early in development, and acentrosomal microtubules are generated by mechanisms that are poorly understood. Here, we show that neuronal migration, development, and polarization depend on the multi-subunit protein HAUS/augmin complex, previously described to be required for mitotic spindle assembly in dividing cells. The HAUS complex is essential for neuronal microtubule organization by ensuring uniform microtubule polarity in axons and regulation of microtubule density in dendrites. Using live-cell imaging and high-resolution microscopy, we found that distinct HAUS clusters are distributed throughout neurons and colocalize with γ-TuRC, suggesting local microtubule nucleation events. We propose that the HAUS complex locally regulates microtubule nucleation events to control proper neuronal development.

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The HAUS/augmin complex regulates migration and polarization in vivo

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Axonal and dendritic development are regulated by HAUS/augmin complex

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HAUS/augmin regulates microtubule density in dendrites and polarity in axons

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Discrete clusters of HAUS/augmin regulate local microtubule nucleation in neurons

Regulation of KIF1A-Driven Dense Core Vesicle Transport: Ca2+/CaM Controls DCV Binding and Liprin-α/TANC2 Recruits DCVs to Postsynaptic Sites

Tight regulation of neuronal transport allows for cargo binding and release at specific cellular locations. The mechanisms by which motor proteins are loaded on vesicles and how cargoes are captured at appropriate sites remain unclear. To better understand how KIF1A-driven dense core vesicle (DCV) transport is regulated, we identified the KIF1A interactome and focused on three binding partners, the calcium binding protein calmodulin (CaM) and two synaptic scaffolding proteins: liprin-α and TANC2. We showed that calcium, acting via CaM, enhances KIF1A binding to DCVs and increases vesicle motility. In contrast, liprin-α and TANC2 are not part of the KIF1A-cargo complex but capture DCVs at dendritic spines. Furthermore, we found that specific TANC2 mutations—reported in patients with different neuropsychiatric disorders—abolish the interaction with KIF1A. We propose a model in which Ca²⁺/CaM regulates cargo binding and liprin-α and TANC2 recruit KIF1A-transported vesicles.

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KIF1A directly interacts with CaM and with the scaffolds liprin-α and TANC2

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KIF1A is regulated by a Ca²⁺/CaM-dependent mechanism, which allows for DCV loading

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Liprin-α and TANC2 are static PSD proteins that are not part of the KIF1A-DCV complex

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KIF1A-driven DCVs are recruited to dendritic spines by liprin-α and TANC2

Feedback-Driven Assembly of the Axon Initial Segment

The axon initial segment (AIS) is a unique neuronal compartment that plays a crucial role in the generation of action potential and neuronal polarity. The assembly of the AIS requires membrane, scaffolding, and cytoskeletal proteins, including Ankyrin-G and TRIM46. How these components cooperate in AIS formation is currently poorly understood. Here, we show that Ankyrin-G acts as a scaffold interacting with End-Binding (EB) proteins and membrane proteins such as Neurofascin-186 to recruit TRIM46-positive microtubules to the plasma membrane. Using in vitro reconstitution and cellular assays, we demonstrate that TRIM46 forms parallel microtubule bundles and stabilizes them by acting as a rescue factor. TRIM46-labeled microtubules drive retrograde transport of Neurofascin-186 to the proximal axon, where Ankyrin-G prevents its endocytosis, resulting in stable accumulation of Neurofascin-186 at the AIS. Neurofascin-186 enrichment in turn reinforces membrane anchoring of Ankyrin-G and subsequent recruitment of TRIM46-decorated microtubules. Our study reveals feedback-based mechanisms driving AIS assembly.

VAP-SCRN1 interaction regulates dynamic endoplasmic reticulum remodeling and presynaptic function

In neurons, the continuous and dynamic endoplasmic reticulum (ER) network extends throughout the axon, and its dysfunction causes various axonopathies. However, it remains largely unknown how ER integrity and remodeling modulate presynaptic function in mammalian neurons. Here, we demonstrated that ER membrane receptors VAPA and VAPB are involved in modulating the synaptic vesicle (SV) cycle. VAP interacts with secernin‐1 (SCRN1) at the ER membrane via a single FFAT‐like motif. Similar to VAP, loss of SCRN1 or SCRN1‐VAP interactions resulted in impaired SV cycling. Consistently, SCRN1 or VAP depletion was accompanied by decreased action potential‐evoked Ca²⁺ responses. Additionally, we found that VAP‐SCRN1 interactions play an important role in maintaining ER continuity and dynamics, as well as presynaptic Ca²⁺ homeostasis. Based on these findings, we propose a model where the ER‐localized VAP‐SCRN1 interactions provide a novel control mechanism to tune ER remodeling and thereby modulate Ca²⁺ dynamics and SV cycling at presynaptic sites. These data provide new insights into the molecular mechanisms controlling ER structure and dynamics, and highlight the relevance of ER function for SV cycling.

MAP7 family proteins regulate kinesin-1 recruitment and activation

Hooikaas et al. show that mammalian MAP7 family proteins act redundantly to activate the kinesin-1 motor protein. Using experiments in cells and in vitro reconstitution assays, they demonstrate that MAP7 proteins promote microtubule recruitment and processivity of kinesin-1 by transiently associating with the stalk region of the motor.

Kinesin-1 is responsible for microtubule-based transport of numerous cellular cargoes. Here, we explored the regulation of kinesin-1 by MAP7 proteins. We found that all four mammalian MAP7 family members bind to kinesin-1. In HeLa cells, MAP7, MAP7D1, and MAP7D3 act redundantly to enable kinesin-1–dependent transport and microtubule recruitment of the truncated kinesin-1 KIF5B-560, which contains the stalk but not the cargo-binding and autoregulatory regions. In vitro, purified MAP7 and MAP7D3 increase microtubule landing rate and processivity of kinesin-1 through transient association with the motor. MAP7 proteins promote binding of kinesin-1 to microtubules both directly, through the N-terminal microtubule-binding domain and unstructured linker region, and indirectly, through an allosteric effect exerted by the kinesin-binding C-terminal domain. Compared with MAP7, MAP7D3 has a higher affinity for kinesin-1 and a lower affinity for microtubules and, unlike MAP7, can be cotransported with the motor. We propose that MAP7 proteins are microtubule-tethered kinesin-1 activators, with which the motor transiently interacts as it moves along microtubules.

Feedback-Driven Mechanisms between Microtubules and the Endoplasmic Reticulum Instruct Neuronal Polarity

Establishment of neuronal polarity depends on local microtubule (MT) reorganization. The endoplasmic reticulum (ER) consists of cisternae and tubules and, like MTs, forms an extensive network throughout the entire cell. How the two networks interact and control neuronal development is an outstanding question. Here we show that the interplay between MTs and the ER is essential for neuronal polarity. ER tubules localize within the axon, whereas ER cisternae are retained in the somatodendritic domain. MTs are essential for axonal ER tubule stabilization, and, reciprocally, the ER is required for stabilizing and organizing axonal MTs. Recruitment of ER tubules into one minor neurite initiates axon formation, whereas ER retention in the perinuclear area or disruption of ER tubules prevent neuronal polarization. The ER-shaping protein P180, present in axonal ER tubules, controls axon specification by regulating local MT remodeling. We propose a model in which feedback-driven regulation between the ER and MTs instructs neuronal polarity.

Peptidylprolyl isomerase A governs TARDBP function and assembly in heterogeneous nuclear ribonucleoprotein complexes

Peptidylprolyl isomerase A (PPIA), also known as cyclophilin A, is a multifunctional protein with peptidyl-prolyl cis-trans isomerase activity. PPIA is also a translational biomarker for amyotrophic lateral sclerosis, and is enriched in aggregates isolated from amyotrophic lateral sclerosis and frontotemporal lobar degeneration patients. Its normal function in the central nervous system is unknown. Here we show that PPIA is a functional interacting partner of TARDBP (also known as TDP-43). PPIA regulates expression of known TARDBP RNA targets and is necessary for the assembly of TARDBP in heterogeneous nuclear ribonucleoprotein complexes. Our data suggest that perturbation of PPIA/TARDBP interaction causes 'TDP-43' pathology. Consistent with this model, we show that the PPIA/TARDBP interaction is impaired in several pathological conditions. Moreover, PPIA depletion induces TARDBP aggregation, downregulates HDAC6, ATG7 and VCP, and accelerates disease progression in the SOD1(G93A) mouse model of amyotrophic lateral sclerosis. Targeting the PPIA/TARDBP interaction may represent a novel therapeutic avenue for conditions involving TARDBP/TDP-43 pathology, such as amyotrophic lateral sclerosis and frontotemporal lobar degeneration.

A possible role of transglutaminase 2 in the nucleus of INS-1E and of cells of human pancreatic islets

Transglutaminase 2 (TG2) is a multifunctional protein with Ca^2 +-dependent transamidating and G protein activity. Previously we reported that the role of TG2 in insulin secretion may involve cytoplasmic actin remodeling and a regulative action on other proteins during granule movement. The aim of this study was to gain a better insight into the role of TG2 transamidating activity in mitochondria and in the nucleus of INS-1E rat insulinoma cell line (INS-1E) during insulin secretion. To this end we labeled INS-1E with an artificial donor (biotinylated peptide), in basal condition and after stimulus with glucose for 2, 5, and 8 min. Biotinylated proteins of the nuclear/mitochondrial-enriched fraction were analyzed using two-dimensional electrophoresis and mass spectrometry. Many mitochondrial proteins involved in Ca^2 + homeostasis (e.g. voltage-dependent anion-selective channel protein, prohibitin and different ATP synthase subunits) and many nuclear proteins involved in gene regulation (e.g. histone H3, barrier to autointegration factor and various heterogeneous nuclear ribonucleoprotein) were identified among a number of transamidating substrates of TG2 in INS-1E. The combined results provide evidence that a temporal link exists between glucose-stimulation, first phase insulin secretion and the action of TG on histone H3 both in INS-1E and human pancreatic islets.

Biological significance

Research into the role of transglutaminase 2 during insulin secretion in INS-1E rat insulinoma cellular model is depicting a complex role for this enzyme. Transglutaminase 2 acts in the different INS-1E compartments in the same way: catalyzing a post-translational modification event of its substrates. In this work we identify some mitochondrial and nuclear substrates of INS-1E during first phase insulin secretion. The finding that TG2 interacts with nuclear proteins that include BAF and histone H3 immediately after (2–5 min) glucose stimulus of INS-1E suggests that TG2 may be involved not only in insulin secretion, as suggested by our previous studies in cytoplasmic INS-1E fraction, but also in the regulation of glucose-induced gene transcription.

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Transglutaminase 2 localizes in the nucleus and in the mitochondrion of INS-1E.

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TG2 acts as a modifying enzyme in both compartments during FPIS.

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TG2 may contribute to Ca^2 + sensing in mitochondrion through its substrates.

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TG2 may contribute to chromatin condensation in nucleus through its substrates.

Measurement of functional residual capacity by helium dilution during partial support ventilation: in vitro accuracy and in vivo precision of the method

OBJECTIVE

Measurement of functional residual capacity (FRC) during controlled and especially during assisted ventilation remains a challenge in the physiological evaluation of ventilated patients. To validate a bag-in-box closed helium dilution technique allowing measurements both during pressure-controlled (PCV) and pressure-support ventilation (PSV).

DESIGN AND SETTING

Experimental study on lung models containing different volumes, and measurements in patients in the intensive care unit of a university hospital. In patients measurements were performed in duplicate during controlled and assisted ventilation.

PATIENTS

Thirty-three patients (aged 57+/-17 years) mechanically ventilated with PCV and PSV.

MEASUREMENTS AND RESULTS

In the lung model assessment of accuracy showed an overall mean difference between FRC measurements and lung model volume of 0.5% (2 SD 5.7%). In patients assessment of repeatability showed a bias between duplicate FRC measurements of -1+/-70 ml (95% CI -141 to +139 ml). The coefficient of variation was of 3.2% for all measurements with a comparable repeatability in PSV and PCV mode (coefficient of variation of 3.4 and 3.2%, respectively). During the rebreathing period a small reduction in tidal volume (-8.5+/-5.4%) and mean airway pressure (-2.3+/-4.7%) was observed with only a 0.3 cmH2O mean increase in PEEP and no change in respiratory rate and I/E ratio.

CONCLUSIONS

This specifically designed closed helium dilution bag-in-box technique allows accurate FRC measurement with good repeatability during both partial PSV and PVC without exposing patients to disconnection and changes in PEEP.

Hemodynamic monitoring in ICU

Oxygen supply to all tissues is possible only in a condition of adequate blood circulation. Oxygen demand is the driving force that is responsive of hemodynamic adjustment. The human body acts on four modulators (intravascular volume, inotropy, vasoactivity, chrono-tropy) in order to adjust the hemodynamic state. Hemodynamic monitoring consists of techniques able to assess the hemodynamic status and to understand the mechanism of patient decompensation; its goal is to maintain adequate tissue perfusion through appropriate therapeutic interventions. An early diagnosis of hemodynamic alteration is crucial for an early treatment; several reports have explored the effectiveness of hemodynamic manipulations and results are conflicting: too many variables can, in fact, modify the results: timing and lenght of the treatment, drugs used, etc. However, at least, in some specific settings, as sepsis, early intervention has a positive impact on mortality. In this presentation it will be briefly analyzed the most common parameters used in the ICU. Arterial pressure, central venous pressure, pulmonary artery catheter derived parameters, SvO2 and their relation with organ perfusion are considered and positive and negative aspects of this type of monitoring is reviewed. Starting from these considerations we would like to underline the importance of understanding the physiological basis of monitoring and the correct interpretation of data in order to have improvement on patient outcome.

[Pharmacotherapy of sepsis]

Despite an increasingly understanding of the pathogenetic mechanisms of sepsis, its mortality remains extremely high, caused mainly by hemodynamic impairment-related alterations frequently present in severe sepsis. Currently, treatment of sepsis is based on hemodynamic support, antibiotic therapy, surgical excision of infectious foci and immunomodulatory therapy. In fact, a massive host inflammatory infection response has recently emerged to substantially contribute to the development of septic shock and multiple organ dysfunction. Many clinical trials on various pharmacological agents have been conducted: glucocorticoids, nonsteroidal anti-inflammatory drugs (NSAIDs), antithrombin III (AT III), anti-endotoxin monoclonal antibodies, nitric oxide inhibitors, interleukin-1 receptor antagonist, anti-tumor necrosis factor (TNF) antibodies. Apart from some likely favourable findings connected to low doses of glucocorticoids, most studies yielded disappointing results. Nevertheless, the use of recombinant human activated protein C (drotrecogin-alpha) has recently proven to have a mortality reduction effect particularly in patients with severe sepsis and dysfunction of at least two organs. Furthermore, the early treatment of hemodynamic instability with volume expanders and vasopressors (early goal-directed therapy), and a strict glycemic control represent important measures in order to significantly reduce mortality from severe sepsis and septic shock, and are fundamental guidelines recommended by most scientific societies (Surviving Sepsis Campaign).