Out-of-hospital cardiac arrest in children: an epidemiological study based on the German Resuscitation Registry identifying modifiable factors for return of spontaneous circulation.

AIM: This work provides an epidemiological overview of out-of-hospital cardiac arrest (OHCA) in children in Germany between 2007 and 2021. We wanted to identify modifiable factors associated with survival. METHODS: Data from the German Resuscitation Registry (GRR) were used, and we included patients registered between 1st January 2007 and 31st December 2021. We included children aged between > 7 days and 17 years, where cardiopulmonary resuscitation (CPR) was started, and treatment was continued by emergency medical services (EMS). Incidences and descriptive analyses are presented for the overall cohort and each age group. Multivariate binary logistic regression was performed on the whole cohort to determine the influence of (1) CPR with/without ventilation started by bystander, (2) OHCA witnessed status and (3) night-time on the outcome hospital admission with return of spontaneous circulation (ROSC). RESULTS: OHCA in children aged < 1 year had the highest incidence of the same age group, with 23.42 per 100 000. Overall, hypoxia was the leading presumed cause of OHCA, whereas trauma and drowning accounted for a high proportion in children aged > 1 year. Bystander-witnessed OHCA and bystander CPR rate were highest in children aged 1-4 years, with 43.9% and 62.3%, respectively. In reference to EMS-started CPR, bystander CPR with ventilation were associated with an increased odds ratio for ROSC at hospital admission after adjusting for age, sex, year of OHCA and location of OHCA. CONCLUSION: This study provides an epidemiological overview of OHCA in children in Germany and identifies bystander CPR with ventilation as one primary factor for survival. Trial registrations German Clinical Trial Register: DRKS00030989, December 28th 2022.

Pain and sedation management and monitoring in pediatric intensive care units across Europe: an ESPNIC survey.

BACKGROUND: Management and monitoring of pain and sedation to reduce discomfort as well as side effects, such as over- and under-sedation, withdrawal syndrome and delirium, is an integral part of pediatric intensive care practice. However, the current state of management and monitoring of analgosedation across European pediatric intensive care units (PICUs) remains unknown. The aim of this survey was to describe current practices across European PICUs regarding the management and monitoring of pain and sedation. METHODS: An online survey was distributed among 357 European PICUs assessing demographic features, drug choices and dosing, as well as usage of instruments for monitoring pain and sedation. We also compared low- and high-volume PICUs practices. Responses were collected from January to April 2021. RESULTS: A total of 215 (60% response rate) PICUs from 27 European countries responded. Seventy-one percent of PICUs stated to use protocols for analgosedation management, more frequently in high-volume PICUs (77% vs 63%, p = 0.028). First-choice drug combination was an opioid with a benzodiazepine, namely fentanyl (51%) and midazolam (71%) being the preferred drugs. The starting doses differed between PICUs from 0.1 to 5 mcg/kg/h for fentanyl, and 0.01 to 0.5 mg/kg/h for midazolam. Daily assessment and documentation for pain (81%) and sedation (87%) was reported by most of the PICUs, using the preferred validated FLACC scale (54%) and the COMFORT Behavioural scale (48%), respectively. Both analgesia and sedation were mainly monitored by nurses (92% and 84%, respectively). Eighty-six percent of the responding PICUs stated to use neuromuscular blocking agents in some scenarios. Monitoring of paralysed patients was preferably done by observation of vital signs with electronic devices support. CONCLUSIONS: This survey provides an overview of current analgosedation practices among European PICUs. Drugs of choice, dosing and assessment strategies were shown to differ widely. Further research and development of evidence-based guidelines for optimal drug dosing and analgosedation assessment are needed.

Autoinflammatory mutation in NLRC4 reveals a leucine-rich repeat (LRR)-LRR oligomerization interface.

BACKGROUND: Monogenic autoinflammatory disorders are characterized by dysregulation of the innate immune system, for example by gain-of-function mutations in inflammasome-forming proteins, such as NOD-like receptor family CARD-containing 4 protein (NLRC4). OBJECTIVE: Here we investigate the mechanism by which a novel mutation in the leucine-rich repeat (LRR) domain of NLRC4 (c.G1965C, p.W655C) contributes to autoinflammatory disease. METHODS: We studied 2 unrelated patients with early-onset macrophage activation syndrome harboring the same de novo mutation in NLRC4. In vitro inflammasome complex formation was quantified by using flow cytometric analysis of apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) specks. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 techniques and lentiviral transduction were used to generate THP-1 cells with either wild-type or mutant NLRC4 cDNA. Cell death and release of IL-1ß/IL-18 were quantified by using flow cytometry and ELISA, respectively. RESULTS: The p.W655C NLRC4 mutation caused increased ASC speck formation, caspase-1-dependent cell death, and IL-1ß/IL-18 production. ASC contributed to p.W655C NLRC4-mediated cytokine release but not cell death. Mutation of p.W655 activated the NLRC4 inflammasome complex by engaging with 2 interfaces on the opposing LRR domain of the oligomer. One key set of residues (p.D1010, p.D1011, p.L1012, and p.I1015) participated in LRR-LRR oligomerization when triggered by mutant NLRC4 or type 3 secretion system effector (PrgI) stimulation of the NLRC4 inflammasome complex. CONCLUSION: This is the first report of a mutation in the LRR domain of NLRC4 causing autoinflammatory disease. c.G1965C/p.W655C NLRC4 increased inflammasome activation in vitro. Data generated from various NLRC4 mutations provides evidence that the LRR-LRR interface has an important and previously unrecognized role in oligomerization of the NLRC4 inflammasome complex.

RNAi profiling of primary human AML cells identifies ROCK1 as a therapeutic target and nominates fasudil as an antileukemic drug.

Acute myeloid leukemia (AML) is characterized by a marked genetic heterogeneity, which complicates the development of novel therapeutics. The delineation of pathways essential within an individual patient's mutational background might overcome this limitation and facilitate personalized treatment. We report the results of a large-scale lentiviral loss-of-function RNA interference (RNAi) screen in primary leukemic cells. Stringent validation identified 6 genes (BNIPL1, ROCK1, RPS13, STK3, SNX27, WDHD1) whose knockdown impaired growth and viability of the cells. Dependence on these genes was not caused by mutation or overexpression, and although some of the candidates seemed to be rather patient specific, others were essential in cells isolated from other AML patients. In addition to the phenotype observed after ROCK1 knockdown, treatment with the approved ROCK inhibitor fasudil resulted in increased apoptosis and decreased viability of primary AML cells. In contrast to observations in some other malignancies, ROCK1 inhibition did not foster growth of immature malignant progenitors but was toxic to this cell fraction in feeder coculture and xenotransplant experiments, indicating a distinct effect of ROCK1 inhibition on leukemic progenitors. We conclude that large-scale RNAi screens in primary patient-derived cells are feasible and can complement other methods for personalized cancer therapies, such as expression and mutation profiling.

Childhood primary large vessel CNS vasculitis: single-centre experience and review of the literature.

Ischaemic brain injuries are rare conditions in the paediatric age group. Main causes include non-arteriosclerotic arteriopathies, which in childhood usually result from primary vasculitis of large or small vessels and lead to impaired perfusion and subsequent ischaemic brain lesions. In accordance with the nomenclature of systemic forms, CNS vasculitis is subdivided into groups, based on the size of affected vessels: angiography-positive primary angiitis of medium-sized and large vessels (pPACNS), and angiography-negative angiitis of small vessels (svPACNS). We report the clinical presentation, diagnostic approach, and therapy of four children with progressive pPACNS. Patients were treated with high-dose corticosteroids and anticoagulation with unfractionated heparin in the acute phase, followed by immune modulatory treatment with mycophenolate mofetil (MMF) and dual antiplatelet therapy with acetylsalicylic acid and clopidogrel. In this manuscript, we illustrate the experience gained in our hospital, resulting in significantly faster diagnosis and treatment initiation, and discuss the applied immune modulating treatment regimen in the context of the literature. Based on our observations, we conclude that immune modulating therapy with initial high-dose corticosteroids, followed by steroid-sparing maintenance treatment with MMF, may be safe and effective in childhood progressive pPACNS.

Functional Restoration of gp91phox-Oxidase Activity by BAC Transgenesis and Gene Targeting in X-linked Chronic Granulomatous Disease iPSCs.

Chronic granulomatous disease (CGD) is an inherited immunodeficiency, caused by the inability of neutrophils to produce functional NADPH oxidase required for fighting microbial infections. The X-linked form of CGD (X-CGD), which is due to mutations in the CYBB (gp91phox) gene, a component of NADPH oxidase, accounts for about two-thirds of CGD cases. We derived induced pluripotent stem cells (iPSCs) from X-CGD patient keratinocytes using a Flp recombinase excisable lentiviral reprogramming vector. For restoring gp91phox function, we applied two strategies: transposon-mediated bacterial artificial chromosome (BAC) transgenesis and gene targeting using vectors with a fixed 5' homology arm (HA) of 8 kb and 3'HA varying in size from 30 to 80 kb. High efficiency of homologous recombination (up to 22%) was observed with increased size of the 3'HA. Both, BAC transgenesis and gene targeting resulted in functional restoration of the gp91phox measured by an oxidase activity assay in X-CGD iPSCs differentiated into the myeloid lineage. In conclusion, we delivered an important milestone towards the use of genetically corrected autologous cells for the treatment of X-CGD and monogenic diseases in general.

Perioperative intravenous fluid therapy in children: guidelines from the Association of the Scientific Medical Societies in Germany.

This consensus- based S1 Guideline for perioperative infusion therapy in children is focused on safety and efficacy. The objective is to maintain or re-establish the child's normal physiological state (normovolemia, normal tissue perfusion, normal metabolic function, normal acid- base- electrolyte status). Therefore, the perioperative fasting times should be as short as possible to prevent patient discomfort, dehydration, and ketoacidosis. A physiologically composed balanced isotonic electrolyte solution (BS) with 1-2.5% glucose is recommended for the intraoperative background infusion to maintain normal glucose concentrations and to avoid hyponatremia, hyperchloremia, and lipolysis. Additional BS without glucose can be used in patients with circulatory instability until the desired effect is achieved. The additional use of colloids (albumin, gelatin, hydroxyethyl starch) is recommended to recover normovolemia and to avoid fluid overload when crystalloids alone are not sufficient and blood products are not indicated. Monitoring should be extended in cases with major surgery, and autotransfusion maneuvers should be performed to assess fluid responsiveness.

Human procaspase-1 variants with decreased enzymatic activity are associated with febrile episodes and may contribute to inflammation via RIP2 and NF-κB signaling.

The proinflammatory enzyme caspase-1 plays an important role in the innate immune system and is involved in a variety of inflammatory conditions. Rare naturally occurring human variants of the caspase-1 gene (CASP1) lead to different protein expression and structure and to decreased or absent enzymatic activity. Paradoxically, a significant number of patients with such variants suffer from febrile episodes despite decreased IL-1ß production and secretion. In this study, we investigate how variant (pro)caspase-1 can possibly contribute to inflammation. In a transfection model, such variant procaspase-1 binds receptor interacting protein kinase 2 (RIP2) via Caspase activation and recruitment domain (CARD)/CARD interaction and thereby activates NF-κB, whereas wild-type procaspase-1 reduces intracellular RIP2 levels by enzymatic cleavage and release into the supernatant. We approach the protein interactions by coimmunoprecipitation and confocal microscopy and show that NF-κB activation is inhibited by anti-RIP2-short hairpin RNA and by the expression of a RIP2 CARD-only protein. In conclusion, variant procaspase-1 binds RIP2 and thereby activates NF-κB. This pathway could possibly contribute to proinflammatory signaling.

Novel Mutation in the DKC1 Gene: Neonatal Hoyeraal-Hreidarsson Syndrome As a Rare Differential Diagnosis in Pontocerebellar Hypoplasia, Primary Microcephaly, and Progressive Bone Marrow Failure.

Primary microcephaly and severe developmental delay are complex but unspecific signs pointing to various genetic or acquired diseases. A concomitant finding of hematological failure may lead to the differential diagnosis of rare genetic diseases such as chromosome breakage disorders or diseases associated with telomere dysfunction. X-linked Hoyeraal-Hreidarsson syndrome (HHS) is a rare heterogenic disorder characterized by severe neurological impairment and progressive bone marrow failure. The latter represents the main cause of mortality, usually in early childhood. We report on the clinical course of an infant with HHS due to a novel mutation in the DKC1 gene and the particular finding of pontocerebellar hypoplasia.

Neonatal Mortality and Morbidity in Regional Provincial Hospitals in the People's Democratic Republic of Laos.

OBJECTIVE: The aim of this study was to identify the causes and incidences of neonatal diseases and deaths in five provincial hospitals in People's Democratic Republic of Laos retrospectively for the years 2010-12. METHODS: Data of neonatal patients were collected before a 3-year-training program for medical and nursing staff involved in the care of newborn infants in the provincial and associated district hospitals. RESULTS: In the years 2010-12, a total of 1673 neonatal patients were treated in the provincial hospitals. The reasons of treatment were as follows: 48% infections, 17% complications of prematurity, 14% intrapartum-related complications and 9% other, not categorized diseases. The average mortality rate in all hospitals was 6.5%. The main causes of death were complications because of prematurity, infectious diseases and asphyxia. CONCLUSION: These data could be the basis for any teaching program aimed at reducing neonatal mortality. Furthermore, they enable an evaluation of the ongoing teaching program.

The histone demethylase UTX regulates stem cell migration and hematopoiesis.

Regulated migration of hematopoietic stem cells is fundamental for hematopoiesis. The molecular mechanisms underlying stem cell trafficking are poorly defined. Based on a short hairpin RNA library and stromal cell-derived factor-1 (SDF-1) migration screening assay, we identified the histone 3 lysine 27 demethylase UTX (Kdm6a) as a novel regulator for hematopoietic cell migration. Using hematopoietic stem and progenitor cells from our conditional UTX knockout (KO) mice, we were able to confirm the regulatory function of UTX on cell migration. Moreover, adult female conditional UTX KO mice displayed myelodysplasia and splenic erythropoiesis, whereas UTX KO males showed no phenotype. During development, all UTX KO female and a portion of UTX KO male embryos developed a cardiac defect, cranioschisis, and died in utero. Therefore, UTY, the male homolog of UTX, can compensate for UTX in adults and partially during development. Additionally, we found that UTX knockdown in zebrafish significantly impairs SDF-1/CXCR4-dependent migration of primordial germ cells. Our data suggest that UTX is a critical regulator for stem cell migration and hematopoiesis.

Expression of the melanoma cell adhesion molecule in human mesenchymal stromal cells regulates proliferation, differentiation, and maintenance of hematopoietic stem and progenitor cells.

The melanoma cell adhesion molecule defines mesenchymal stromal cells in the human bone marrow that regenerate bone and establish a hematopoietic microenvironment in vivo. The role of the melanoma cell adhesion molecule in primary human mesenchymal stromal cells and the maintenance of hematopoietic stem and progenitor cells during ex vivo culture has not yet been demonstrated. We applied RNA interference or ectopic overexpression of the melanoma cell adhesion molecule in human mesenchymal stromal cells to evaluate the effect of the melanoma cell adhesion molecule on their proliferation and differentiation as well as its influence on co-cultivated hematopoietic stem and progenitor cells. Knockdown and overexpression of the melanoma cell adhesion molecule affected several characteristics of human mesenchymal stromal cells related to osteogenic differentiation, proliferation, and migration. Furthermore, knockdown of the melanoma cell adhesion molecule in human mesenchymal stromal cells stimulated the proliferation of hematopoietic stem and progenitor cells, and strongly reduced the formation of long-term culture-initiating cells. In contrast, melanoma cell adhesion molecule-overexpressing human mesenchymal stromal cells provided a supportive microenvironment for hematopoietic stem and progenitor cells. Expression of the melanoma cell adhesion molecule increased the adhesion of hematopoietic stem and progenitor cells to human mesenchymal stromal cells and their migration beneath the monolayer of human mesenchymal stromal cells. Our results demonstrate that the expression of the melanoma cell adhesion molecule in human mesenchymal stromal cells determines their fate and regulates the maintenance of hematopoietic stem and progenitor cells through direct cell-cell contact.

Factors influencing the success and complications of intraosseous access in pediatric patients-a prospective nationwide surveillance study in Germany.

Background: Vascular access is essential for the efficient treatment of critically ill children, but it can be difficult to obtain. Our study was conducted to analyze the feasibility and short-term safety of intraosseous access (IO) use as well as factors influencing its success and the incidence of complications in pediatric emergencies and resuscitation. This dataset of systematically documented intraosseous access attempts constitutes one of the largest published in the literature. Methods: Two-year nationwide prospective surveillance study in Germany from July 2017 to June 2019. Pediatric hospitals anonymously reported the case data of all children aged 28 days to 18 years who arrived with or were treated with an intraosseous access to the German Pediatric Surveillance Unit (GPSU). The main outcomes were the occurrence of complications, overall success and success at the first attempt. The influence of individual factors on outcomes was evaluated using multivariate regression models. Results: A total of 417 patients underwent 549 intraosseous access attempts. The overall rates of success and success at the first attempt were 98.3% and 81.9%, respectively. Approximately 63.6% of patients were successfully punctured within 3 min from the time of indication. Approximately 47.7% of IO access attempts required patient resuscitation. Dislocation [OR 17.74 (5.32, 59.15)] and other complications [OR 9.29 (2.65, 32.55)] occurred more frequently in the prehospital environment. A total of 22.7% of patients experienced minor complications, while 2.5% of patients experienced potentially severe complications. Conclusion: We conclude that intraosseous access is a commonly used method for establishing emergency vascular access in children, being associated with a low (age-dependent) rate of severe complications and providing mostly reliable vascular access despite a relatively high rate of dislocation.

Assessment and management of iatrogenic withdrawal syndrome and delirium in pediatric intensive care units across Europe: An ESPNIC survey.

INTRODUCTION: Analgesia and sedation are essential for the care of children in the pediatric intensive care unit (PICU); however, when prolonged, they may be associated with iatrogenic withdrawal syndrome (IWS) and delirium. We sought to evaluate current practices on IWS and delirium assessment and management (including non-pharmacologic strategies as early mobilization) and to investigate associations between the presence of an analgosedation protocol and IWS and delirium monitoring, analgosedation weaning, and early mobilization. METHODS: We conducted a multicenter cross-sectional survey-based study collecting data from one experienced physician or nurse per PICU in Europe from January to April 2021. We then investigated differences among PICUs that did or did not follow an analgosedation protocol. RESULTS: Among 357 PICUs, 215 (60%) responded across 27 countries. IWS was systematically monitored with a validated scale in 62% of PICUs, mostly using the Withdrawal Assessment Tool-1 (53%). The main first-line treatment for IWS was a rescue bolus with interruption of weaning (41%). Delirium was systematically monitored in 58% of PICUs, mostly with the Cornell Assessment of Pediatric Delirium scale (48%) and the Sophia Observation Scale for Pediatric Delirium (34%). The main reported first-line treatment for delirium was dexmedetomidine (45%) or antipsychotic drugs (40%). Seventy-one percent of PICUs reported to follow an analgosedation protocol. Multivariate analyses adjusted for PICU characteristics showed that PICUs using a protocol were significantly more likely to systematically monitor IWS (odds ratio [OR] 1.92, 95% confidence interval [CI] 1.01-3.67) and delirium (OR 2.00, 95% CI 1.07-3.72), use a protocol for analgosedation weaning (OR 6.38, 95% CI 3.20-12.71) and promote mobilization (OR 3.38, 95% CI 1.63-7.03). CONCLUSIONS: Monitoring and management of IWS and delirium are highly variable among European PICUs. The use of an analgosedation protocol was associated with an increased likelihood of monitoring IWS and delirium, performing a structured analgosedation weaning and promoting mobilization. Education on this topic and interprofessional collaborations are highly needed to help reduce the burden of analgosedation-associated adverse outcomes.

Pediatric intensive care unit admissions network-rationale, framework and method of operation of a nationwide collaborative pediatric intensive care research network in Germany.

The Pediatric Intensive Care Unit Admissions (PIA) network aims to establish a nationwide database in Germany to gather epidemiological, clinical, and outcome data on pediatric critical illness. The heterogeneity of pediatric patients in intensive care units (PICU) poses challenges in obtaining sufficient case numbers for reliable research. Multicentered approaches, such as patient registries, have proven effective in collecting large-scale data. However, Germany lacks a systematic registration system for pediatric intensive care admissions, hindering epidemiological and outcome assessments. The PIA network intends to address these gaps and provide a framework for clinical and epidemiological research in pediatric intensive care. The network will interconnect PICUs across Germany and collect structured data on diagnoses, treatment, clinical course, and short-term outcomes. It aims to identify areas for improvement in care, enable disease surveillance, and potentially serve as a quality control tool. The PIA network builds upon the existing infrastructure of the German Pediatric Surveillance Unit ESPED and utilizes digitalized data collection techniques. Participating units will complete surveys on their organizational structure and equipment. The study population includes patients aged ≥28 days admitted to participating PICUs, with a more detailed survey for cases meeting specific criteria. Data will be collected by local PIA investigators, anonymized, and entered into a central database. The data protection protocol complies with regulations and ensures patient privacy. Quarterly data checks and customized quality reports will be conducted to monitor data completeness and plausibility. The network will evaluate its performance, data collection feasibility, and data quality. Eligible investigators can submit proposals for data analyses, which will be reviewed and analyzed by trained statisticians or epidemiologists. The PIA network aims to improve pediatric intensive care medicine in Germany by providing a comprehensive understanding of critical illness, benchmarking treatment quality, and enabling disease surveillance.

Recommendations on the structure, personal, and organization of intensive care units.

Background: Intensive care units (ICU) are central facilities of medical care in hospitals world-wide and pose a significant financial burden on the health care system. Objectives: To provide guidance and recommendations for the requirements of (infra)structure, personal, and organization of intensive care units. Design and setting: Development of recommendations based on a systematic literature search and a formal consensus process from a group of multidisciplinary and multiprofessional specialists from the German Interdisciplinary Association of Intensive Care and Emergency Medicine (DIVI). The grading of the recommendation follows the report from an American College of Chest Physicians Task Force. Results: The recommendations cover the fields of a 3-staged level of intensive care units, a 3-staged level of care with respect to severity of illness, qualitative and quantitative requirements of physicians and nurses as well as staffing with physiotherapists, pharmacists, psychologists, palliative medicine and other specialists, all adapted to the 3 levels of ICUs. Furthermore, proposals concerning the equipment and the construction of ICUs are supplied. Conclusion: This document provides a detailed framework for organizing and planning the operation and construction/renovation of ICUs.

[DIVI-Recommendations on the infrastruture of adult intensive care units]. / DIVI-Empfehlung zur Struktur und Ausstattung von Intensivstationen 2022 (Erwachsene).

This document on the Structure and Equipment for Intensive Care Units of the German Association for Intensive and Emergency Care (DIVI) aims at providing guidance and recommendations for the requirements of (infra)structure, personal, and organization of intensive care units. The recommendations are based on a systematic literature search and a formal consensus process from a group of multi-disciplinary and multiprofessional specialists from the DIVI. The recommendations comprise a 3-staged level of intensive care units, a 3-staged level of care with respect to severity of illness, the staffing requirement of physicians, nurses, physiotherapists, pharmacists, psychologists, and other specialists. Furthermore, proposals concerning the equipment and the construction of ICUs are supplied.

Intraosseous access in neonates is feasible and safe - An analysis of a prospective nationwide surveillance study in Germany.

Background: This was a prospective surveillance study to investigate reports on the safety and frequency of use of intraosseous (IO) access in neonates. Methods: Over a two-year period, paediatric hospitals in Germany were asked to report all cases of IO access to the nationwide Surveillance Unit for Rare Paediatric Diseases (ESPED). Hospitals reporting a case submitted responses via an anonymised electronic questionnaire, providing details on indication, success rate, system used, location, duration to first successful IO access, complications, alternative access attempts and short-term outcome. We present a subset of data for IO use in infants of less than 28 days. Results: A total of 161 neonates (145 term and 16 preterm born infants) with 206 IO access attempts were reported. In 146 neonates (91%), IO access was successfully established, and success was achieved with the first attempt in 109 neonates (75%). There was no significant impact of gestational age or provider's educational level on success rates. In 71 infants with successful IO access (79%), the estimated duration of placement was less than 3 min. The proximal tibia was the predominant site used. A semiautomatic battery-driven device was used in 162 attempts (88%). The most often applied medications via IO access were crystalloid fluid and adrenaline. Potentially severe complications occurred in 9 patients (6%). Conclusion: Within this surveillance study, IO access in neonates was feasible and safe. IO access is an important alternative for vascular access in neonates.

Listening to the Whispers in Neuroimmune Crosstalk: A Comprehensive Workflow to Investigate Neurotrophin Receptor p75NTR Under Endogenous, Low Abundance Conditions.

Inflammatory conditions are critically influenced by neuroimmune crosstalk. Cytokines and neurotrophic factors shape the responses of both nervous and immune systems. Although much progress has been made, most findings to date are based on expression of recombinant (tagged) proteins. The examination of receptor interactions by immunoprecipitation (IP) at endogenous levels provides further insight into the more subtle regulations of immune responses. Here, we present a comprehensive workflow and an optimized IP protocol that provide step-by-step instructions to investigate neurotrophin receptor p75NTR at endogenous, low abundance levels: from lysate preparation and confirmation of receptor expression to antibody validation and successful detection of protein-protein interactions. We employ human melanoma cell line A375 to validate specific antibodies and IP conditions, and apply these methods to explore p75NTR interactions in human leukemic plasmacytoid dendritic cell line PMDC05 detecting 14-3-3ϵ:p75NTR interaction in this cell type. With p75NTR as an exemplary protein, our approach provides a strategy to detect specific interaction partners even under endogenous, low abundance expression conditions.