Biology subjects

Brouwer, S.

Publications and source records attributed to Brouwer, S..

6 recordsLinked to original sources

bioRxiv2026

A repair-associated bronchial epithelial differentiation trajectory through KRT14+ basal and hillock-like cells drives airway inflammation and remodelling in childhood-onset asthma

The bronchial epithelium in asthma is vulnerable to damage and has impaired barrier function, but the mechanisms by which it contributes to airway inflammation and remodelling remain unclear. Here, we dissect these epithelial and immunological disease mechanisms by establishing a comprehensive single cell atlas of the bronchial wall from 21 patients with childhood-onset asthma and 25 matched healthy controls. We identify a novel asthma-associated non-canonical epithelial differentiation trajectory in which a repair-associated KLF4+ basal cell subset differentiates into KRT13+ hillock-like cells through a proliferative KRT14+ intermediate. In vitro cultured matched primary bronchial epithelial cells show that this trajectory is retained in absence of exogenous factors. We find that IL-13 induces hillock-like cell differentiation into CEACAM5hi goblet cells, driving goblet cell metaplasia. Repair-associated basal cells and transitioning CEACAM5hi hillock-like cells strongly contribute to airway inflammation and remodelling. In turn, dendritic cells and mast cells promote a state of highly active epithelial differentiation, which shows increased multiciliated cell fate decisions, in concordance with an increase in multiciliated cell death observed in asthma. Proportions of the epithelial cells of the non-canonical differentiation trajectory are associated with clinical outcomes such as disease severity, FeNO, and small airway function.

immunology↗

bioRxiv2025

Glycerol suppresses lactose-dependent growth of Streptococcus pyogenes through a transcription-independent mechanism

Streptococcus pyogenes (group A Streptococcus; GAS) requires flexible metabolic regulation to adapt to diverse host environments; however, its physiological responses to lactose and glycerol remain poorly characterized compared with glucose. In this study, we analyzed three representative serotype M1 GAS strains--the M1global strain 5448, the ancestral M1 strain SF370, and SP1380 as a representative of the recently emerged M1UK lineage. Glycerol consistently suppressed lactose-dependent growth across all strains, while glycerol-dependent respiratory activity was observed in 5448 and SF370 but was absent in SP1380. RNA-seq analysis of strain 5448 revealed no significant transcriptional changes upon glycerol supplementation, indicating that this inhibitory effect likely occurs through a non-transcriptional mechanism. In contrast, lactose supplementation induced distinct transcriptional programs compared with glucose, including coordinated expression changes gene sets regulated by carbohydrate-responsive transcription factors (CcpA, MalR, and NanR) and by the virulence regulator Mga and the stress-response regulator Rgg. Together, these findings identify a previously unrecognized layer of carbon source-dependent metabolic regulation and growth control in GAS.

microbiology↗

bioRxiv2022

IL-33 induced gene expression in activated Th2 effector cells is dependent on IL-1RL1 haplotype and disease status

BackgroundIL-33 can activate Th2 cells after binding to the IL-1RL1/IL-1RAcP receptor. However, it is unknown whether disease or genetic make-up regulate IL33 responsiveness of Th2 cells. ObjectiveWe investigated whether IL-1RL1 asthma risk haplotypes or asthma status influence IL-33-induced Th2 transcriptomic responses in vitro. MethodsCD4+ T cells from 16 asthma patients and matched controls, stratified for IL-1RL1 haplotype, were differentiated into Th2 effector cells, and re-stimulated in the presence or absence of IL-33, followed by RNA-sequencing and differential gene expression analysis. Association of IL-33-induced gene signatures with clinical parameters was tested in U-BIOPRED sputum transcriptomic data. ResultsPresence of IL-33 during Th2 cell re-stimulation results in extensive changes in gene expression, affecting a large proportion of the activated Th2 cell transcriptome. IL-33 induced more genes in Th2 cells from donors with asthma than in controls. However, the IL-33 effects were strongest in Th2 cells carrying the IL-1RL1 risk haplotype, as evidenced by a significantly increased effect size compared to controls. A gene signature of IL-33 induced genes in Th2 cells showed a strong positive correlation with macrophage counts and pauci-granulocytic asthma in sputum transcriptomic data from the U-BIOPRED study. ConclusionThe risk IL-1RL1 haplotype strongly increases the sensitivity of Th2 effector cell for IL-33-mediated regulation of gene expression, while asthma status has an independent effect. The IL-33 gene signature was not associated with type-2 high or eosinophilic asthma in sputum transcriptomic data from U-BIOPRED. Clinical OutcomeCellular sensitivity to IL-33 depends on genetic makeup and asthma disease status. Capsule summaryIL-33 strongly alters gene expression of activated Th2 cells, dependent on asthma disease status and IL-1RL1 risk haplotype. IL-33 driven gene signature in sputum transcriptomic data identifies pauci-granulocytic asthma.

molecular biology↗

bioRxiv2020

Prophage exotoxins enhance colonization fitness in epidemic scarlet fever-causing Streptococcus pyogenes

The re-emergence of scarlet fever poses a new global public health threat. The capacity of North-East Asian serotype M12 (emm12) Streptococcus pyogenes (group A Streptococcus, GAS) to cause scarlet fever has been linked epidemiologically to the presence of novel prophages, including prophage {Phi}HKU.vir encoding the secreted superantigens SSA and SpeC and the DNase Spd1. Here we report the comprehensive molecular characterization of {Phi}HKU.vir-encoded exotoxins. We demonstrate that streptolysin O (SLO)-induced glutathione efflux from host cellular stores is a previously unappreciated GAS virulence mechanism that promotes SSA release and activity, representing the first description of a thiol-activated bacterial superantigen. Spd1 is required for optimal growth in human blood, confers resistance to neutrophil killing, and degrades neutrophil extracellular traps (NETs). Investigating single, double and triple isogenic knockout mutants of the {Phi}HKU.vir-encoded exotoxins, we find that SpeC and Spd1 act synergistically to facilitate nasopharyngeal colonization in a mouse model. These results offer insight into the etiology and pathogenesis of scarlet fever-causing GAS mediated by phage {Phi}HKU.vir exotoxins.

microbiology↗

bioRxiv2020

A role for glutathione in buffering excess intracellular copper in Streptococcus pyogenes

Copper (Cu) is an essential metal for bacterial physiology but in excess it is bacteriotoxic. To limit Cu levels in the cytoplasm, most bacteria possess a transcriptionally-responsive system for Cu export. In the Gram-positive human pathogen Streptococcus pyogenes (Group A Streptococcus, GAS), this system is encoded by the copYAZ operon. In this study, we demonstrate that the site of GAS infection in vivo represents a Cu-rich environment but inactivation of the copA Cu efflux gene does not reduce virulence in a mouse model of invasive disease. In vitro, Cu treatment leads to multiple observable phenotypes, including defects in growth and viability, decreased fermentation, inhibition of glyceraldehyde 3-phosphate dehydrogenase (GapA) activity, and misregulation of metal homeostasis, likely as a consequence of mismetalation of non-cognate metal-binding sites. Surprisingly, the onset of these effects is delayed by [~]4 h even though expression of copZ is upregulated immediately upon exposure to Cu. We further show that the onset of all phenotypes coincides with depletion of intracellular glutathione (GSH). Supplementation with extracellular GSH replenishes the intracellular pool of this thiol and suppresses all the observable effects of Cu treatment. Our results indicate that GSH contributes to buffering of excess intracellular Cu when the transcriptionally-responsive Cu export system is overwhelmed. Thus, while the copYAZ operon is responsible for Cu homeostasis, GSH has a role in Cu tolerance that allows bacteria to maintain metabolism even in the presence of an excess of this metal ion. This study advances fundamental understanding of Cu handling in the bacterial cytoplasm. IMPORTANCEThe control of intracellular metal availability is fundamental to bacterial physiology. In the case of copper (Cu), it is established that rising intracellular Cu levels eventually fill the metal-sensing site of the endogenous Cu-sensing transcriptional regulator, which in turn induces transcription of a copper export pump. This response caps intracellular Cu availability below a well-defined threshold and prevents Cu toxicity. Glutathione, abundant in many bacteria, is known to bind Cu and is long assumed to contribute to bacterial Cu handling. However, there is some ambiguity since neither its biosynthesis nor uptake is Cu-regulated. Furthermore, there is little experimental support for this role of glutathione beyond measurement of the effect of Cu on growth of glutathione-deficient mutants. Our work with Group A Streptococcus provides new evidence that glutathione increases the threshold of intracellular Cu availability that can be tolerated by bacteria and thus advances fundamental understanding of bacterial Cu handling.

microbiology↗

bioRxiv2019

A cellular census of healthy lung and asthmatic airway wall identifies novel cell states in health and disease

Human lungs enable efficient gas exchange, and form an interface with the environment which depends on mucosal immunity for protection against infectious agents. Tightly controlled interactions between structural and immune cells are required to maintain lung homeostasis. Here, we use single cell transcriptomics to chart the cellular landscape of upper and lower airways and lung parenchyma in health. We report location-dependent airway epithelial cell states, and a novel subset of tissue-resident memory T cells. In lower airways of asthma patients, mucous cell hyperplasia is shown to stem from a novel mucous ciliated cell state, as well as goblet cell hyperplasia. We report presence of pathogenic effector Th2 cells in asthma, and find evidence for type-2 cytokines in maintaining the altered epithelial cell states. Unbiased analysis of cell-cell interactions identify a shift from airway structural cell communication in health to a Th2-dominated interactome in asthma.

immunology↗