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BackgroundPost–COVID-19 syndrome (PCS; also known as “long COVID”) is a relatively novel disease comprising physical, psychological, and cognitive complaints persisting several weeks to months after acute infection with SARS-CoV-2. Approximately 10% of patients with COVID-19 are affected by long-term symptoms. However, effective treatment strategies are lacking. The ErgoLoCo (Occupational Therapy [Ergotherapie] for Long COVID) study was designed to develop and evaluate a novel occupational therapy (OT) concept of online delivery of therapy for long COVID. ObjectiveThe primary study objective is to assess the feasibility of the online OT intervention in PCS. Secondary aims include the evaluation of online OT concerning cognitive problems, occupational performance, and social participation. MethodsThis randomized controlled interventional pilot study involves parallel mixed methods process analyses and a realist evaluation approach. A total of 80 clients with PCS aged at least 16 years will be recruited into two interventional groups. The control cohort (watch and wait) comprises 80 clients with long COVID. Treatment is provided through teletherapy (n=40) or delivery of prerecorded videos (n=40) using the same standardized OT concept twice weekly over 12 weeks. Analyses of quantitative questionnaires and qualitative interviews based on the theoretical framework of acceptability will be performed to assess feasibility. Focus group meetings will be used to assess how acceptable and helpful the intervention was to the participating occupational therapists. Standardized tests will be used to assess the initial efficacy of the intervention on neurocognitive performance; limitations in mobility, self-care, and everyday activities; pain; disabilities; quality of life (QoL); social participation; and anxiety and depression in PCS, and the possible effects of online OT on these complaints. ResultsThe German Ministry of Education and Research provided funding for this research in March 2022. Data collection took place from October 2022 to August 31, 2023. Data analysis will be completed by the end of April 2024. We anticipate publishing the results in the fall of 2024. ConclusionsDespite the enormous clinical need, effective and scalable treatment options for OT clients who have PCS remain scarce. The ErgoLoCo study will assess whether online-delivered OT is a feasible treatment approach in PCS. Furthermore, this study will assess the effect of the intervention on cognitive symptoms, QoL, and occupational performance and participation in everyday life. Particular emphasis will be placed on the experiences of clients and occupational therapists with digitally delivered OT. This study will pave the way for novel and effective treatment strategies in PCS. Trial RegistrationGerman Clinical Trial Registry DRKS00029990; https://drks.de/search/de/trial/DRKS00029990 International Registered Report Identifier (IRRID)PRR1-10.2196/50230

A single population of interferon-regulatory factor 8 (Irf8)-dependent conventional dendritic cell (cDC type1) is considered to be responsible for both immunogenic and tolerogenic responses depending on the surrounding cytokine milieu. Here, we challenge this concept of an omnipotent single Irf8-dependent cDC1 cluster through analysis of pulmonary cDCs at single cell resolution. We report existence of a pulmonary cDC1 cluster lacking Xcr1 with an immunogenic signature that clearly differs from the Xcr1 positive cDC1 cluster. The Irf8+Batf3+Xcr1- cluster expresses high levels of pro-inflammatory genes associated with antigen presentation, migration and co-stimulation such as Ccr7, Cd74, MHC-II, Ccl5, Il12b and Relb while, the Xcr1+ cDC1 cluster expresses genes corresponding to immune tolerance mechanisms like Clec9a, Pbx1, Cadm1, Btla and Clec12a. In concordance with their pro-inflammatory gene expression profile, the ratio of Xcr1- cDC1s but not Xcr1+cDC1 is increased in the lungs of allergen-treated mice compared to the control group, in which both cDC1 clusters are present in comparable ratios. The existence of two distinct Xcr1+ and Xcr1- cDC1 clusters is furthermore supported by velocity analysis showing markedly different temporal patterns of Xcr1- and Xcr1+cDC1s. In summary, we present evidence for the existence of two different cDC1 clusters with distinct immunogenic profiles in vivo. Our findings have important implications for DC-targeting immunomodulatory therapies.

Background Paediatric community-acquired pneumonia (CAP) is a leading cause of paediatric morbidity. However, particularly for outpatients with paediatric CAP, data on aetiology and management are scarce. Methods The prospective pedCAPNETZ study multicentrically enrols children and adolescents with outpatient-treated or hospitalised paediatric CAP in Germany. Blood and respiratory specimens were collected systematically, and comprehensive analyses of pathogen spectra were conducted. Follow-up evaluations were performed until day 90 after enrolment. Results Between December 2014 and August 2020, we enrolled 486 children with paediatric CAP at eight study sites, 437 (89.9%) of whom had radiographic evidence of paediatric CAP. Median (interquartile range) age was 4.5 (1.6–6.6) years, and 345 (78.9%) children were hospitalised. The most prevalent symptoms at enrolment were cough (91.8%), fever (89.2%) and tachypnoea (62.0%). Outpatients were significantly older, displayed significantly lower C-reactive protein levels and were significantly more likely to be symptom-free at follow-up days 14 and 90. Pathogens were detected in 90.3% of all patients (one or more viral pathogens in 68.1%; one or more bacterial strains in 18.7%; combined bacterial/viral pathogens in 4.1%). Parainfluenza virus and Mycoplasma pneumoniae were significantly more frequent in outpatients. The proportion of patients with antibiotic therapy was comparably high in both groups (92.4% of outpatients versus 86.2% of hospitalised patients). Conclusion We present first data on paediatric CAP with comprehensive analyses in outpatients and hospitalised cases and demonstrate high detection rates of viral pathogens in both groups. Particularly in young paediatric CAP patients with outpatient care, antibiotic therapy needs to be critically debated.

Abstract Background Respiratory syncytial virus (RSV) is the most common cause of acute lower respiratory tract infection in infants. Globally, RSV is responsible for approximately 3.2 million hospital admissions and about 60,000 in-hospital deaths per year. Methods Infection with RespIratory Syncytial Virus (IRIS) is an observational, multi-centre study enrolling infants with severe RSV infection and healthy controls. Inclusion criteria are age between 0 and 36 months and hospitalisation due to RSV infection at three German sites. Exclusion criteria are premature birth, congenital or acquired bronchopulmonary or cardiac diseases, and immunodeficiency. Healthy control probands are enrolled via recruitment of patients undergoing routine surgical procedures. Blood and respiratory specimens are collected upon admission, and RSV and other pathogens are analysed by multiplex polymerase chain reaction. Different biomaterials, including plasma, nasal lining fluid, blood cells, DNA, and RNA specimens, are sampled in a dedicated biobank. Detailed information on demographic characteristics and medical history is recorded, and comprehensive clinical data, including vital signs, medication, and interventions. Discussion The IRIS study aims to discover host and viral factors controlling RSV disease courses in infants. The approach including multi-omics characterisation in clinically well-characterized children with RSV bronchiolitis seeks to improve our understanding of the immune response against this virus. It may disclose novel diagnostic and treatment approaches for respiratory infections in infants. Trial registration: ClinicalTrials.gov, NCT04925310. Registered 01 October 2021—Retrospectively registered. https://clinicaltrials.gov/ct2/show/NCT04925310?cond=NCT04925310&draw=2&rank=1

Abstract The presence of acute infectious respiratory diseases (ARD) is one of the main reasons why recently arrived refugees seek medical help. This paper investigates the incidence rates of acute respiratory diseases in an adult refugee population as well as associated sociodemographic factors and drug treatments. We conducted a retrospective observational study of deidentified medical records. The data were collected between 2015 and 2019 in the health care centers of two large German initial reception centers for refugees. Multivariable analyses controlling for sociodemographics were carried out using generalized estimating equations. Out of 10,431 eligible residents, 6965 medical encounters of 2840 adult patients were recorded over 30 months. Of all the adult patients, 34.4% sought medical help for a respiratory symptom or diagnosis at least once. Older patients and patients from Sub-Saharan Africa sought help less often. The occurrence of ARD showed a typical distribution over the course of the year. Facility occupancy was not associated with ARD occurrence. Acute respiratory symptoms are a leading cause for adult refugee patients to seek medical care. The doctor contact rates due to ARD were consistently two to three times higher among refugees than among German residents.

Background: Different asthma phenotypes are driven by molecular endotypes. A Th1-high phenotype is linked to severe, therapy-refractory asthma, subclinical infections and neutrophil inflammation. Previously, we found neutrophil granulocytes (NGs) from asthmatics exhibit decreased chemotaxis towards leukotriene B4 (LTB4), a chemoattractant involved in inflammation response. We hypothesized that this pattern is driven by asthma in general and aggravated in a Th1-high phenotype.Methods: NGs from asthmatic nd healthy children were stimulated with 10 nM LTB4/100 nM N-formylmethionine-leucyl-phenylalanine and neutrophil migration was documented following our prior SiMA (simplified migration assay) workflow, capturing morphologic and dynamic parameters from single-cell tracking in the images. Demographic, clinical and serum cytokine data were determined in the ALLIANCE cohort.Results: A reduced chemotactic response towards LTB4 was confirmed in asthmatic donors regardless of inhaled corticosteroid (ICS) treatment. By contrast, only NGs from ICS-treated asthmatic children migrate similarly to controls with the exception of Th1-high donors, whose NGs presented a reduced and less directed migration towards the chemokines. ICS-treated and Th1-high asthmatic donors present an altered surface receptor profile, which partly correlates with migration.Conclusions: Neutrophil migration in vitro may be affected by ICS-therapy or a Th1-high phenotype. This may be explained by alteration of receptor expression and could be used as a tool to monitor asthma treatment.

Gain-of-function variants in the stimulator of interferon response cGAMP interactor 1 (STING1) gene cause STING-Associated Vasculopathy with onset in Infancy (SAVI). Previously, only heterozygous and mostly de novo STING1 variants have been reported to cause SAVI. Interestingly, one variant that only leads to SAVI when homozygous, namely c.841C>T p.(Arg281Trp), has recently been described. However, there are no entries in public databases regarding an autosomal recessive pattern of inheritance. Here, we report four additional unrelated SAVI patients carrying c.841C>T in homozygous state. All patients had interstitial lung disease and displayed typical interferon activation patterns. Only one child displayed cutaneous vasculitis, while three other patients presented with a relatively mild SAVI phenotype. Steroid and baricitinib treatment had a mitigating effect on the disease phenotype in two cases, but failed to halt disease progression. Heterozygous c.841C>T carriers in our analysis were healthy and showed normal interferon activation. Literature review identified eight additional cases with autosomal recessive SAVI caused by c.841C>T homozygosity. In summary, we present four novel and eight historic cases of autosomal recessive SAVI. We provide comprehensive clinical data and show treatment regimens and clinical responses. To date, SAVI has been listed as an exclusively autosomal dominant inherited trait in relevant databases. With this report, we aim to raise awareness for autosomal recessive inheritance in this rare, severe disease which may aid in early diagnosis and development of optimized treatment strategies.

Abstract Background Glycosylation is a common and complex type of protein posttranslational modification. Altered glycosylation of immunoglobulins in autoimmune diseases has led to the “altered glycan hypothesis” postulating existence of a unique glycan signature on immune cells and extracellular proteins characterized by site‐specific relative abundances of individual glycan structures and glycosylation patterns. However, it is not clear how glycosylation on leukocyte subpopulations differ between states of health or inflammation. Hypothesis Glycosphingolipid patterns on immune cells of forkhead‐box‐P3‐deficient scurfy mice differs from those on wild‐type immune cells. Methods T cells and dendritic cells were isolated from spleens of either wild‐type or age‐matched scurfy mice. Glycosphingolipids of CD4+ T cells and splenic dendritic cells from wild‐type and scurfy mice were then analyzed by multiplexed capillary gel electrophoresis coupled to laser‐induced fluorescence detection (xCGE‐LIF). In addition, flow cytometry and ChipCytometry were used to access expression patterns of various C‐type lectin receptors on antigen‐presenting cells from various organs of both wild‐type and scurfy mice. Results We, hereby report differential expression of glycosphingolipids in health and under inflammatory conditions as reflected in wild‐type and scurfy mice. Furthermore, we observed that the absence of functional regulatory T cells correlated with elevated expression of CLEC‐7A and CD205 but a reduction in levels of CLEC12A and CD206 on antigen‐presenting cells. Conclusion We hereby show that the absence of functional regulatory T cells affects expression pattern and quantities of glycosphingolipids on immune cells. Thus, glycosphingolipids could serve as biomarkers for mapping genetical and homeostatic perturbances such as those resulting from a diseased condition.

IntroductionThis study analyses how healthcare workers (HCWs) perceived risks, protection and preventive measures during the COVID-19 pandemic in relation to medically approved risks and organizational measures. The aim is to explore “blind spots” of pandemic protection and make mental health needs of HCWs visible.MethodsWe have chosen an “optimal-case” scenario of a high-income country with a well-resourced hospital sector and low HCW infection rate at the organizational level to explore governance gaps in HCW protection. A German multi-method hospital study at Hannover Medical School served as empirical case; document analysis, expert information and survey data (n = 1,163) were collected as part of a clinical study into SARS-CoV-2 serology testing during the second wave of the pandemic (November 2020-February 2021). Selected survey items included perceptions of risks, protection and preventive measures. Descriptive statistical analysis and regression were undertaken for gender, profession and COVID-19 patient care.ResultsThe results reveal a low risk of 1% medically approved infections among participants, but a much higher mean personal risk estimate of 15%. The majority (68.4%) expressed “some” to “very strong” fear of acquiring infection at the workplace. Individual protective behavior and compliance with protective workplace measures were estimated as very high. Yet only about half of the respondents felt strongly protected by the employer; 12% even perceived “no” or “little” protection. Gender and contact with COVID-19 patients had no significant effect on the estimations of infection risks and protective workplace behavior, but nursing was correlated with higher levels of personal risk estimations and fear of infection.ConclusionsA strong mismatch between low medically approved risk and personal risk perceptions of HCWs brings stressors and threats into view, that may be preventable through better information, training/education and risk communication and through investment in mental health and inclusion in pandemic preparedness plans.

Abstract Background Serology testing is explored for epidemiological research and to inform individuals after suspected infection. During the coronavirus disease 2019 (COVID-19) pandemic, frontline healthcare professionals (HCP) may be at particular risk for infection. No longitudinal data on functional seroconversion in HCP in regions with low COVID-19 prevalence and low pre-test probability exist. Methods In a large German university hospital, we performed weekly questionnaire assessments and anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin G (IgG) measurements with various commercial tests, a novel surrogate virus neutralisation test, and a neutralisation assay using live SARS-CoV-2. Results From baseline to week 6, 1080 screening measurements for anti-SARS CoV-2 (S1) IgG from 217 frontline HCP (65% female) were performed. Overall, 75.6% of HCP reported at least one symptom of respiratory infection. Self-perceived infection probability declined over time (from mean 20.1% at baseline to 12.4% in week 6, p

Abstract Background The COVID-19 pandemic has disrupted healthcare systems worldwide. In addition to the direct impact of the virus on patient morbidity and mortality, the effect of lockdown strategies on health and healthcare utilization have become apparent. Little is known on the effect of the pandemic on pediatric and adolescent medicine. We examined the impact of the pandemic on pediatric emergency healthcare utilization. Methods We conducted a monocentric, retrospective analysis of n = 5,424 pediatric emergency department visits between January 1st and April 19th of 2019 and 2020, and compared healthcare utilization during the pandemic in 2020 to the same period in 2019. Results In the four weeks after lockdown in Germany began, we observed a massive drop of 63.8% in pediatric emergency healthcare utilization (mean daily visits 26.8 ± SEM 1.5 in 2019 vs. 9.7 ± SEM 1 in 2020, p

Abstract Background The purpose of our study was to describe and evaluate management, performance and results of Tuberculosis (TB)-screening among refugees and asylum seekers in a rural area in Germany in 2015. Methods Refugees or asylum seekers, staying in shared-accommodation are obligated to participate on screening chest X-ray (CXR) in order to screen for signs of potentially infectious pulmonary TB (German Protection against Infection Act and German Asylum Procedure Act). n = 705 individuals underwent screening chest X-ray (CXR) to detect pulmonary TB in September and October 2015 on site. One experienced radiologist interpreted and reported each CXR within 24 h after the enrollment in the screening program and results were sent to the local Public Health Department for potential further medical care. Image abnormalities suggestive for TB were defined according to established radiographic criteria such as pleural effusion, cavitation, consolidation, fibrous scarring or calcification. Only in case of TB-suggestive findings on CXR, further diagnostics were arranged (pulmonological examination, follow-up CXR, sputum culture, interferon-gamma release assay, bronchoscopy). Follow-up data was collected in collaboration with the local Public Health Department. Descriptive statistics were calculated using GraphPad Prism software. Results n = 637 CXR examinations (90%) did not show abnormal findings, n = 54 CXR (8%) showed incidental findings, and n = 14 CXR (2%) were suspicious for acute TB. Of these, n = 14 individuals, eight underwent further TB diagnostics. Active TB was confirmed in one individual (0.001% of the screening cohort). Conclusions Our cohort reflects current immigrations statistics in Europe and illustrates an overall low TB prevalence amongst individuals entering Germany in 2015. However, our findings support the improvement of diagnostic algorithms.

Abstract Background Pediatric community acquired pneumonia (pedCAP) is one of the leading causes for childhood morbidity accounting for up to 20% of pediatric hospital admissions in high income countries. In spite of its high morbidity, updated epidemiological and pathogen data after introduction of preventive vaccination and novel pathogen screening strategies are limited. Moreover, there is a need for validated recommendations on diagnostic and treatment regimens in pedCAP. Through collection of patient data and analysis of pathogen and host factors in a large sample of unselected pedCAP patients in Germany, we aim to address and substantially improve this situation. Methods pedCAPNETZ is an observational, multi-center study on pedCAP. Thus far, nine study centers in hospitals, outpatient clinics and practices have been initiated and more than 400 patients with radiologically confirmed pneumonia have been enrolled, aiming at a total of 1000 study participants. Employing an online data base, information on disease course, treatment as well as demographical and socioeconomical data is recorded. Patients are followed up until day 90 after enrollment; Comprehensive biosample collection and a central pedCAPNETZ biobank allow for in-depth analyses of pathogen and host factors. Standardized workflows to assure sample logistics and data management in more than fifteen future study centers have been established. Discussion Through comprehensive epidemiological, clinical and biological analyses, pedCAPNETZ fills an important gap in pediatric and infection research. To secure dissemination of the registry, we will raise clinical and scientific awareness at all levels. We aim at participating in decision making processes for guidelines and prevention strategies. Ultimately, we hope the results of the pedCAPNETZ registry will help to improve care and quality of life in pedCAP patients in the future.

Optimal pre-analytical conditions for blood sample processing and isolation of selected cell populations for subsequent transcriptomic and epigenomic studies are required to obtain robust and reproducible results. This pilot study was conducted to investigate the potential effects of timing of CD4+ T-cell processing from peripheral blood of atopic and non-atopic adults on their transcriptomic and epigenetic profiles. Two heparinized blood samples were drawn from each of three atopic and three healthy individuals. For each individual, CD4+ T-cells were isolated from the first blood sample within 2 h (immediate) or from the second blood sample after 24 h storage (delayed). RNA sequencing (RNA-Seq) and histone H3K27 acetylation chromatin immunoprecipitation sequencing (ChIP-Seq) analyses were performed. A multiplicity of genes was shown to be differentially expressed in immediately processed CD4+ T-cells from atopic versus healthy subjects. These differences disappeared when comparing delayed processed cells due to a drastic change in expression levels of atopy-related genes in delayed processed CD4+ T-cells from atopic donors. This finding was further validated on the epigenomic level by examining H3K27 acetylation profiles. In contrast, transcriptomic and epigenomic profiles of blood CD4+ T-cells of healthy donors remained rather unaffected. Taken together, for successful transcriptomics and epigenomics studies, detailed standard operation procedures developed on the basis of samples from both healthy and disease conditions are implicitly recommended.

Abstract Background Providing adequate healthcare to newly arrived refugees is considered one of the significant challenges for the German healthcare system. These refugees can be classified mainly into two groups: asylum seekers (who have applied for asylum after arrival in Germany and are waiting for the refugee-status decision) and resettlement refugees (who have already been granted asylum status before arriving in Germany). Whereas earlier studies have explored the health status of asylum seekers especially in terms of mental and behavioural disorders and infectious diseases without distinguishing between these two groups, our study aims to evaluate possible relationships of asylum status and medical needs of these two groups with a special focus on mental and behavioural disorders and infectious diseases. Methods In this retrospective observational study, collected data on all asylum-seeker and resettlement-refugee patients (N = 2252) of a German reception centre (August 2017 to August 2018) is analysed by absolute and relative frequencies and medians. Patient data, collected by chart review, include age, gender, country of origin, asylum status, and diagnoses (ICD-10). To describe the relationship between sociodemographic factors (including asylum status) and diagnoses, we used tests of significance and bivariate correlations with Spearman correlation coefficients. All collected data are pseudonymised. Results Of all 2252 patients, 43% were resettlement refugees. In almost all ICD-10 categories, asylum seekers received significantly more diagnoses than resettlement refugees. According to our data, asylum seekers presented with mental and behavioural disorders nine times more often (9%) than resettlement refugees (1%). In the case of infectious diseases, the results are mixed: asylum seekers were twice as frequently (11%) diagnosed with certain infectious and parasitic diseases than resettlement refugees (5%), but resettlement refugees were treated twice as often (22% of the asylum seekers and 41% of the resettlement refugees) for diseases of the respiratory system, of which 84% were acute respiratory infections (in both groups). Conclusion This study indicates that patients with unregulated migration more frequently present symptoms of psychiatric diseases and somatoform symptoms than resettlement refugees. A health policy approach within migration policy should aim to enable persecuted persons to migrate under regulated and safe conditions. Trial registration German Clinical Trials Register: DRKS00013076, retrospectively registered on 29.09.2017.

Summary: Induced pluripotent stem cell (iPSC)-derived hematopoietic cells represent a highly attractive source for cell and gene therapy. Given the longevity, plasticity, and self-renewal potential of distinct macrophage subpopulations, iPSC-derived macrophages (iPSC-Mφ) appear of particular interest in this context. We here evaluated the airway residence, plasticity, and therapeutic efficacy of iPSC-Mφ in a murine model of hereditary pulmonary alveolar proteinosis (herPAP). We demonstrate that single pulmonary macrophage transplantation (PMT) of 2.5–4 × 106 iPSC-Mφ yields efficient airway residence with conversion of iPSC-Mφ to an alveolar macrophage (AMφ) phenotype characterized by a distinct surface marker and gene expression profile within 2 months. Moreover, PMT significantly improves alveolar protein deposition and other critical herPAP disease parameters. Thus, our data indicate iPSC-Mφ as a source of functional macrophages displaying substantial plasticity and therapeutic potential that upon pulmonary transplantation will integrate into the lung microenvironment, adopt an AMφ phenotype and gene expression pattern, and profoundly ameliorate pulmonary disease phenotypes. : Mucci and colleagues demonstrate marked plasticity of iPSC-derived macrophages and rapid adoption of an alveolar macrophage phenotype upon pulmonary transplantation, as well as profound therapeutic efficacy of iPSC-derived macrophages in the context of the severe lung disease pulmonary alveolar proteinosis. Key words: iPSC, hematopoiesis, macrophages, lung, cell therapy

Abstract Background Asthma and wheezing disorders in childhood and adulthood are clinically heterogeneous regarding disease presentation, natural course, and response to treatment. Deciphering common disease mechanisms in distinct subgroups requires harmonized molecular (endo-) phenotyping of both children and adult patients with asthma in a prospective, longitudinal setting. Methods The ALL Age Asthma Cohort (ALLIANCE) of the German Center for Lung Research (DZL) is a prospective, multi-center, observational cohort study with seven recruiting sites across Germany. Data are derived from four sources: (a) patient history from medical records, (b) standardized questionnaires and structured interviews, (c) telephone interviews, and (d) objective measurements. Objective measurements include amongst others lung function and quantitative assessment of airway inflammation and exhaled breath, peripheral blood, skin, nasal, pharyngeal, and nasopharyngeal swabs, nasal secretions, primary nasal epithelial cells, and induced sputum. In cases, objective measurements and biomaterial collection are performed regularly, while control subjects are only examined once at baseline. Discussion The standardized and detailed collection of epidemiological and physiological data, and the molecular deep phenotyping of a comprehensive range of biomaterials in a considerable number of study participants across all ages are the outstanding characteristics of this multi-center cohort. Despite extensive biomaterial sampling, and a recruitment strategy that also includes pre-school children as young as 6 months, attrition is low. In children 83.9%, and in adults 90.5% attended the 12-month follow-up. The earliest time-point to include cases, however, is disease manifestation. Therefore, unraveling mechanisms that drive disease onset is limited, as this question can only be answered in a population-based birth cohort. Nonetheless, ALLIANCE offers a unique, integrative and inter-disciplinary framework with a comprehensive molecular approach in a prospective and identical fashion across ages in order to identify biomarkers and predictors for distinct childhood wheeze and asthma trajectories as well as their further course during adulthood. Ultimately, this approach aims to translate its most significant findings into clinical practice, and to improve asthma transition from adolescence to adulthood. Trial registration NCT02496468 for pediatric arm, NCT02419274 for adult arm.

Summary: Mendelian susceptibility to mycobacterial disease (MSMD) is caused by inborn errors of interferon gamma (IFNγ) immunity and is characterized by severe infections by weakly virulent mycobacteria. Although IFNγ is the macrophage-activating factor, macrophages from these patients have never been studied. We demonstrate the generation of heterozygous and compound heterozygous (iMSMD-cohet) induced pluripotent stem cells (iPSCs) from a single chimeric patient, who suffered from complete autosomal recessive IFNγR1 deficiency and received bone-marrow transplantation. Loss of IFNγR1 expression had no influence on the macrophage differentiation potential of patient-specific iPSCs. In contrast, lack of IFNγR1 in iMSMD-cohet macrophages abolished IFNγ-dependent phosphorylation of STAT1 and induction of IFNγ-downstream targets such as IRF-1, SOCS-3, and IDO. As a consequence, iMSMD-cohet macrophages show impaired upregulation of HLA-DR and reduced intracellular killing of Bacillus Calmette-Guérin. We provide a disease-modeling platform that might be suited to investigate novel treatment options for MSMD and to gain insights into IFNγ signaling in macrophages.

Induced pluripotent stem cells (iPSCs) represent an innovative source for the standardized in vitro generation of macrophages (Mφ). We here describe a robust and efficient protocol to obtain mature and functional Mφ from healthy as well as disease-specific murine iPSCs. With regard to morphology, surface phenotype, and function, our iPSC-derived Mφ (iPSC-Mφ) closely resemble their counterparts generated in vitro from bone marrow cells. Moreover, when we investigated the feasibility of our differentiation system to serve as a model for rare congenital diseases associated with Mφ malfunction, we were able to faithfully recapitulate the pathognomonic defects in GM-CSF signaling and Mφ function present in hereditary pulmonary alveolar proteinosis (herPAP). Thus, our studies may help to overcome the limitations placed on research into certain rare disease entities by the lack of an adequate supply of disease-specific primary cells, and may aid the development of novel therapeutic approaches for herPAP patients.

Tissue macrophages are important components of tissue homeostasis and inflammatory pathologies. In the peritoneal cavity, resident macrophages interact with a variety of immune cells and can exhibit broad range of phenotypes and functions. Forkhead-box-P3 (FOXP3)+ regulatory T cells (Tregs) play an indispensable role in maintaining immunological tolerance, yet whether, and how the pathological condition that results from the lack of functional Tregs affects peritoneal macrophages (PM) is largely unknown. We used FOXP3-deficient scurfy (Sf) mice to investigate PM behavior in terms of the missing crosstalk with Tregs. Here, we report that Treg deficiency induced a marked increase in PM numbers, which was reversed after adoptive transfer of CD4+ T cells or neutralization of macrophage colony-stimulating factor. Ex vivo assays demonstrated a pro-inflammatory state of PM from Sf mice and signs of excessive activation and exhaustion. In-depth immunophenotyping of Sf PM using single-cell chipcytometry and transcriptome analysis revealed upregulation of molecules involved in the initiation of innate and adaptive immune responses. Moreover, upon transfer to non-inflammatory environment or after injection of CD4+ T cells, PM from Sf mice reprogramed their functional phenotype, indicating remarkable plasticity. Interestingly, frequencies, and immune polarization of large and small PM subsets were dramatically changed in the FOXP3-deficient mice, suggesting distinct origin and specialized function of these subsets in inflammatory conditions. Our findings demonstrate the significant impact of Tregs in shaping PM identity and dynamics. A better understanding of PM function in the Sf mouse model may have clinical implication for the treatment of immunodysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome, and other forms of immune-mediated enteropathies.

Interleukin-3 (IL-3) is capable of supporting the proliferation of a broad range of hematopoietic cell types, whereas granulocyte colony-stimulating factor (G-CSF) and macrophage CSF (M-CSF) represent critical cytokines in myeloid differentiation. When this was investigated in a pluripotent-stem-cell-based hematopoietic differentiation model, IL-3/G-CSF or IL-3/M-CSF exposure resulted in the continuous generation of myeloid cells from an intermediate myeloid-cell-forming complex containing CD34+ clonogenic progenitor cells for more than 2 months. Whereas IL-3/G-CSF directed differentiation toward CD45+CD11b+CD15+CD16+CD66b+ granulocytic cells of various differentiation stages up to a segmented morphology displaying the capacity of cytokine-directed migration, respiratory burst response, and neutrophil-extracellular-trap formation, exposure to IL-3/M-CSF resulted in CD45+CD11b+CD14+CD163+CD68+ monocyte/macrophage-type cells capable of phagocytosis and cytokine secretion. Hence, we show here that myeloid specification of human pluripotent stem cells by IL-3/G-CSF or IL-3/M-CSF allows for prolonged and large-scale production of myeloid cells, and thus is suited for cell-fate and disease-modeling studies as well as gene- and cell-therapy applications.

Cellular therapy with chimeric antigen receptor (CAR)-redirected cytotoxic T cells has shown impressive efficacy in the treatment of hematologic malignancies. We explored a regulatory T cell (Treg)-based therapy in the treatment of allergic airway inflammation, a model for asthma, which is characterized by an airway hyper-reactivity (AHR) and a chronic, T helper-2 (Th2) cell-dominated immune response to allergen. To restore the immune balance in the lung, we redirected Tregs by a CAR toward lung epithelia in mice upon experimentally induced allergic asthma, closely mimicking the clinical situation. Adoptively transferred CAR Tregs accumulated in the lung and in tracheobronchial lymph nodes, reduced AHR and diminished eosinophilic airway inflammation, indicated by lower cell numbers in the bronchoalveolar lavage fluid and decreased cell infiltrates in the lung. CAR Treg cells furthermore prevented excessive pulmonary mucus production as well as increase in allergen-specific IgE and Th2 cytokine levels in exposed animals. CAR Tregs were more efficient in controlling asthma than non-modified Tregs, indicating the pivotal role of specific Treg cell activation in the affected organ. Data demonstrate that lung targeting CAR Treg cells ameliorate key features of experimental airway inflammation, paving the way for cell therapy of severe allergic asthma.

Following publication of the original article [1], the author flagged aspects of the article that affected readability of some of the article’s scientific content.