Christian Herr

Background: Chronic obstructive pulmonary disease (COPD) is a leading cause of global morbidity and mortality, and its heterogeneity demands better biomarkers of severity and progression risk. Extracellular vesicles (EVs) are promising blood-based biomarkers, but have not been examined for COPD severity and outcomes in a large multicentre cohort. Methods: We analysed 600 COSYCONET participants (up to 54 months of follow-up). EV surface markers were profiled with the MACSPlex EV Kit IO. Cross-sectional associations with severity (GOLD, FEV1) were primary (ordinal and linear regression); longitudinal trajectories and all-cause mortality were prespecified exploratory endpoints. Results: Six EV markers showed robust associations with cross-sectional severity: CD29, CD49e and CD31 increased with severity (a cell-adhesion/matrix-remodelling signal), whereas CD81 and CD8 decreased; HLA-ABC (increasing) was less specific. No marker was linked to FEV1 decline. After FDR correction, lower levels of three markers with higher 54-month mortality (all HR<1): CD25 (HR 0.77, 95% CI 0.65-0.90, q=0.018), CD56 (HR 0.75, 95% CI 0.63-0.89, q=0.018) and CD142 (HR 0.74, 95% CI 0.60-0.90, q=0.024). CD25 and CD142 also improved reclassification, CD56 did not; a CD25 + CD69 combination showed the largest incremental signal (ΔC 0.017, 95% CI 0.002-0.032, p=0.027). Conclusion: Circulating EV surface markers are associated with cross-sectional COPD severity. Exploratory analyses nominate CD25, CD142 and CD25 + CD69 as candidate prognostic markers requiring external validation, suggesting minimally invasive EV profiling could complement clinical assessment in COPD.

SARS-CoV-2 infection affects multiple immune mechanisms and leads to severe COVID-19 and death, in part related to infection-induced or pre-existing autoantibodies. Here, we describe severe COVID-19 to associate with autoantibodies against interleukin-1 receptor antagonist (IL-1Ra) and progranulin (PGRN), endogenous antagonists of IL-1 and TNF signaling, respectively. These autoantibodies coincide with hyperphosphorylation of IL-1Ra (Thr111) or PGRN (Ser81), form immune complexes independent of phosphorylation, reduce antigen plasma levels, and permit enhanced IL-1 and TNF signaling. Using phage-display selected Fabs specific for hyperphosphorylated isoforms, we track phospho-antigens and autoantibodies in a German national pandemic network cohort. Most seropositive patients show both autoantibodies. Levels peak at baseline and decline over 12 months, with phospho-antigens decreasing before autoantibodies. Seropositivity associates with hyperinflammation and cytokine profiles. Importantly, signaling by key inflammatory cytokines induce IL-1Ra and PGRN hyperphosphorylation in healthy monocytes, but require up to 1000-fold higher doses than in monocytes from previously seropositive severe COVID-19 survivors.

Respiratory infections, including pneumonia and COVID-19, are major causes of global mortality and morbidity. Recent advancements in organ-on-a-chip (OOC) technologies have paved the way for human-based disease models, offering new tools for studying disease mechanisms and accelerating drug development. The aim of this study was to establish a lung-liver fluidic system to study the interaction of both organ modules during infection. A two organ (lung-liver) fluidic system was established using primary human bronchial (HBECs) or alveolar type epithelial cells (AT) for the lung module and Huh-7 cells for the liver module. Inactivated non-typeable Haemophilus influenzae (NTHi) and Pseudomonas aeruginosa PAO1 (PAO1) were applied to the lung module. Secreted mediators were screened by dot-blot analysis and quantified. The impact of bacteria-exposed epithelial cells on the liver cell transcriptome was analyzed via mRNA sequencing. Lung and liver cells established stable cultures in a circulatory fluidic system. Activation of HBECs or ATCs with NTHi or PAO1 resulted in the secretion of multiple inflammatory mediators into the microfluidic medium including tumor necrosis factor-alpha (TNF-α), monocyte chemotactic protein-1 (MCP-1) and macrophage inflammatory protein-1-α (MIP-1α). Addition of lung cells and application of bacterial onto the HBEC module led to significant transcriptomic alterations in the liver cell module. Gene ontology enrichment analysis showed the induction of various pathways involved in host defense, metabolism, repair, and acute phase response. In conclusion, a two-organ lung-liver fluidic system was established to study the interaction of the organ modules during infection. Mediators like cytokines are released from epithelial culture modules into the fluidic circulation after exposure to bacterial pathogens that significantly modify the gene expression patterns of liver cells.

Tracheal tuft cells shape immune responses in the airways. While some of these effects have been attributed to differential release of either acetylcholine, leukotriene C4 and/or interleukin-25 depending on the activating stimuli, tuft cell-dependent mechanisms underlying the recruitment and activation of immune cells are incompletely understood. Here we show that Pseudomonas aeruginosa infection activates mouse tuft cells, which release ATP via pannexin 1 channels. Taste signaling through the Trpm5 channel is essential for bacterial tuft cell activation and ATP release. We demonstrate that activated tuft cells recruit dendritic cells to the trachea and lung. ATP released by tuft cells initiates dendritic cell activation, phagocytosis and migration. Tuft cell stimulation also involves an adaptive immune response through recruitment of IL-17A secreting T helper cells. Collectively, the results provide a molecular framework defining tuft cell dependent regulation of both innate and adaptive immune responses in the airways to combat bacterial infection.

The human microbiome emerges as a promising reservoir for diagnostic markers and therapeutics. Since host-associated microbiomes at various body sites differ and diseases do not occur in isolation, a comprehensive analysis strategy highlighting the full potential of microbiomes should include diverse specimen types and various diseases. To ensure robust data quality and comparability across specimen types and diseases, we employ standardized protocols to generate sequencing data from 1931 prospectively collected specimens, including from saliva, plaque, skin, throat, eye, and stool, with an average sequencing depth of 5.3 gigabases. Collected from 515 patients, these samples yield an average of 3.7 metagenomes per patient. Our results suggest significant microbial variations across diseases and specimen types, including unexpected anatomical sites. We identify 583 unexplored species-level genome bins (SGBs) of which 189 are significantly disease-associated. Of note, the existence of microbial resistance genes in one specimen was indicative of the same resistance genes in other specimens of the same patient. Annotated and previously undescribed SGBs collectively harbor 28,315 potential biosynthetic gene clusters (BGCs), with 1050 significant correlations to diseases. Our combinatorial approach identifies distinct SGBs and BGCs, emphasizing the value of pan-body pan-disease microbiomics as a source for diagnostic and therapeutic strategies.

Background: Infections of the respiratory tract such as pneumonia or COVID-19 cause high mortality and morbidity worldwide. Organ-on-a-chip (OC) technologies have been developed in the last years to establish human-based disease models, to study basic disease mechanisms and to provide a tool to speed up drug development. The aim of this study was to establish a lung-liver microfluidic system to study the interaction of both organ modules during infection. Methods: A two organ (lung / liver) microfluidic system was established using primary human bronchial (HBECs) or alveolar type epithelial cells (ATC) for the lung module and Huh-7 cells for the liver module. Inactivated non typeable Haemophilus influenzae (NTHi) and Pseudomonas aeruginosa PAO1 (PAO1) were applied to the lung module. Secreted mediators were screened by dot-blot analysis and quantified. The effect of lung epithelial bacterial stimulation on the liver cell transcriptome was analyzed by mRNA sequencing. Results: Lung and liver cells established stable cultures in a circulatory microfluidic system. Activation of HBECs or ATCs with NTHi or PAO1 resulted in the secretion of multiple inflammatory mediators into the microfluidic medium including TNF-α, monocyte chemotactic protein-1 (MCP-1) and macrophage inflammatory protein-3 (MIP-3). Addition of lung cells and application of bacterial onto the HBECs module resulted in the gross change of the transcriptome of the liver cell module. Gene ontology enrichment analysis showed the induction of various pathways involved in host defense, metabolisms, repair, and acute phase response. Interpretation: In conclusion, a two-organ lung/liver microfluidic system was established to study the interaction of the organ modules during infection. Mediators released from epithelial culture modules into the microfluidic circulation after exposure to bacterial pathogens significantly modify the gene expression patterns of liver cells. Funding: This research was funded by the German Federal Ministry of Education and Research (BMBF), 031L0153 VISION “Alternativmethoden zum Tierversuch” and the Dr. Rolf M. Schwiete Stiftung.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causing the coronavirus disease 2019 (COVID-19) pandemic, leads to illness and death. Various risk factors for a severe course, such as higher age, male gender and pre-existing illnesses are known. However, pathophysiological risk factors are largely unclear. Notably, the mild course of disease in children is conspicuous. Angiotensin converting enzyme 2 (ACE2) serves as a receptor for SARS-CoV-2 and is a key enzyme in infection. Differences in the distribution of ACE2 can provide insights into different courses of COVID-19. Our aim was to elucidate the role of ACE2 as a pathophysiological risk factor by measuring soluble ACE2 (sACE2) via ELISA in blood samples (lithium-heparin-plasma or serum) of 367 individuals including children and adults with and without COVID-19. sACE2-levels were compared between the groups according to age and sex. In adults and children with COVID-19, sACE2-concentrations are significantly higher compared to healthy individuals. sACE2-levels increase with age and are lower in children compared to adults with COVID-19. Sex doesn’t significantly influence sACE2-concentration. It remains unclear whether sACE2 concentrations increase because of the infection and what factors could influence this response. In conclusion, the increase of sACE2-concentration with age could indicate that ACE2 concentrations mirror increased COVID-19 severity.

Pneumonia is a common cause of morbidity and mortality and is most often caused by bacterial pathogens. COVID-19 is characterized by lung infection with potential progressive organ failure. The systemic consequences of both disease on the systemic blood metabolome are not fully understood. The aim of this study was to compare the blood metabolome of both diseases and we hypothesize that plasma metabolomics may help to identify the systemic effects of these diseases. Therefore, we profiled the plasma metabolome of 43 cases of COVID-19 pneumonia, 23 cases of non-COVID-19 pneumonia, and 26 controls using a non-targeted approach. Metabolic alterations differentiating the three groups were detected, with specific metabolic changes distinguishing the two types of pneumonia groups. A comparison of venous and arterial blood plasma samples from the same subjects revealed the distinct metabolic effects of pulmonary pneumonia. In addition, a machine learning signature of four metabolites was predictive of the disease outcome of COVID-19 subjects with an area under the curve (AUC) of 86 ± 10%. Overall, the results of this study uncover systemic metabolic changes that could be linked to the etiology of COVID-19 pneumonia and non-COVID-19 pneumonia.

Background: Glycyrrhizin, an active component of liquorice root extract, exhibits antiviral and immunomodulatory properties by direct inhibition of the pro-inflammatory alarmin HMGB1 (High-mobility group box 1).Objective: The aim of this study was to explore the role of liquorice intake on the viral entry receptor ACE2 (angiotensin-converting enzyme 2) and the immunoregulatory HMGB1 in healthy individuals and to explore HMGB1 expression in coronavirus disease 2019 (COVID-19) or non-COVID-19 in ARDS (acute respiratory distress syndrome patients).Material and methods: This study enrolled 43 individuals, including hospitalised patients with i) acute respiratory distress syndrome (ARDS) due to COVID-19 (n = 7) or other underlying causes (n = 12), ii) mild COVID-19 (n = 4) and iii) healthy volunteers (n = 20). Healthy individuals took 50 g of liquorice (containing 3% liquorice root extract) daily for 7 days, while blood samples were collected at baseline and on day 3 and 7. Changes in ACE2 and HMGB1 levels were determined by Western blot analysis and enzyme-linked immunosorbent assay, respectively. Additionally, HMGB1 levels were measured in hospitalised COVID-19 patients with mild disease or COVID-19 associated acute respiratory distress syndrome (ARDS) and compared with a non-COVID-19-ARDS group.Results: Liquorice intake significantly reduced after 7 days both cellular membranous ACE2 expression (-51% compared to baseline levels, p = 0.008) and plasma HMGB1 levels (-17% compared to baseline levels, p<0.001) in healthy individuals. Half of the individuals had a reduction in ACE2 levels of at least 30%. HMGB1 levels in patients with mild COVID-19 and ARDS patients with and without COVID-19 were significantly higher compared with those of healthy individuals (+317%, p = 0.002), but they were not different between COVID-19 and non-COVID-19 ARDS.Conclusions: Liquorice intake modulates ACE2 and HMGB1 levels in healthy individuals. HMGB1 is enhanced in mild COVID-19 and in ARDS with and without COVID-19, warranting evaluation of HMGB1 as a potential treatment target and glycyrrhizin, which is an active component of liquorice root extract, as a potential treatment in COVID-19 and non-COVID-19 respiratory disease.

Airway mucociliary regeneration and function are key players for airway defense and are impaired in chronic obstructive pulmonary disease (COPD). Using transcriptome analysis in COPD-derived bronchial biopsies, we observed a positive correlation between cilia-related genes and microRNA-449 (miR449). In vitro, miR449 was strongly increased during airway epithelial mucociliary differentiation. In vivo, miR449 was upregulated during recovery from chemical or infective insults. miR0449^−/− mice (both alleles are deleted) showed impaired ciliated epithelial regeneration after naphthalene and Haemophilus influenzae exposure, accompanied by more intense inflammation and emphysematous manifestations of COPD. The latter occurred spontaneously in aged miR449^−/− mice. We identified Aurora kinase A and its effector target HDAC6 as key mediators in miR449-regulated ciliary homeostasis and epithelial regeneration. Aurora kinase A is downregulated upon miR449 overexpression in vitro and upregulated in miR449^−/− mouse lungs. Accordingly, imaging studies showed profoundly altered cilia length and morphology accompanied by reduced mucociliary clearance. Pharmacological inhibition of HDAC6 rescued cilia length and coverage in miR449^−/− cells, consistent with its tubulin-deacetylating function. Altogether, our study establishes a link between miR449, ciliary dysfunction, and COPD pathogenesis.