Biology subjects

Distler, T.

Publications and source records attributed to Distler, T..

5 recordsLinked to original sources

bioRxiv2026

Pyocyanin disrupts airway regeneration to favor chronic Pseudomonas aeruginosa infection

During chronic infections, host tissues undergo repeated cycles of injury and repair while being exposed to bacterial products. Although many virulence factors trigger immune responses, whether bacterial metabolites alter tissue architecture by disrupting regenerative programs remains largely unexplored. Here, using a primary-cell-derived human lung microtissue model, we show that the redox-active metabolite pyocyanin (PYO), produced by the opportunistic pathogen Pseudomonas aeruginosa, disrupts airway epithelial regeneration and reshapes tissue architecture, amplifying infection. PYO exposure impairs epithelial repair, leading to defects in mucociliary clearance and promoting bacterial growth. Single-cell transcriptomics and imaging reveal that PYO exposure during basal cell differentiation alters epithelial cell-type composition. Keratin-13-rich cells promote the emergence of squamous regions with defective ciliogenesis, resulting in functional defects. After characterizing how PYO remodels the epithelium, we tested how these changes impact bacterial fitness. Using transposon-insertion sequencing and live imaging of infections, we show that these regeneration defects improve the fitness of mutants that tend to form biofilms, a common feature of chronic infections. Together, our results reveal that PYO reshapes regenerative trajectories and tissue architecture in ways that subsequently alter infection outcomes, highlighting the role of secreted metabolites as potential modulators of tissue regeneration during chronic lung infections.

microbiology↗

bioRxiv2026

Pseudomonas aeruginosa balances cytotoxicity and motility to counter phagocytosis by macrophages

During chronic lung infections, Pseudomonas aeruginosa diversifies under selection from antibiotics, metabolic constraints, and host defenses. Macrophages are key sentinels of the innate immune system and play a central role in clearing airway pathogens. Yet, how they process heterogeneous bacterial populations remains poorly understood. Here, we investigate how P. aeruginosa evades phagocytosis under conditions that mimic chronic infection. We use an attenuated mutant lacking a functional type III secretion system (T3SS), which reduces macrophage killing, allowing us to isolate determinants of bacterial susceptibility to phagocytosis. Using transposon insertion sequencing (Tn-seq), we identify bacterial fitness factors under phagocytic selection. Our screen reveals that disruption of genes involved in swimming and twitching motility reduces uptake by macrophages. We find that motility defects interfere with the physical interactions between bacteria and macrophages. Live-cell imaging shows that motility-deficient bacteria exhibit reduced surface exploration and unstable attachment to macrophages, limiting their internalization. Clinical isolates with reduced swimming or twitching motility display similarly impaired uptake. Restoring T3SS activity in these motility mutants rescues cytotoxicity toward macrophages, with one notable exception: flagellum-less, hyper-piliated P. aeruginosa remains avirulent and resistant to phagocytosis due to their lack of engagement with macrophages. Together, these results support two distinct immune evasion strategies: during chronic infection, reduced motility promotes a "freeze"-like state that limits detection and engulfment, whereas during acute infection, P. aeruginosa adopts a "fight"-like strategy by activating its T3SS to eliminate macrophages. SummaryHow immune cells recognize and eliminate bacteria is typically explained by molecular signaling, yet the role of physical interactions remains unclear. We show that bacterial motility is a key determinant of phagocytosis by macrophages. Using functional genomics and live imaging, we find that swimming and twitching motility promote bacterial uptake by enabling effective surface exploration and stable physical engagement with macrophages. Loss of motility commonly observed in chronic P. aeruginosa infections reduces these interactions and allows bacteria to evade engulfment. In contrast, during acute infection, bacteria rely on T3SS-mediated killing of macrophages, independently of motility. These findings reveal that phagocytosis is governed not only by immune recognition but also by bacterial mechanical behavior, and identify a shift in host-pathogen interactions associated with chronic versus acute infection. More broadly, this work establishes mechanics as an important dimension of immune evasion.

microbiology↗

bioRxiv2025

Fibrin-containing Hydrogels Regulate Human Astrocyte State and Neuronal Reprogramming

Astrocytes are key components in reactive gliosis after brain injury, yet defined in vitro models dissecting the influence of extracellular matrix (ECM) components enriched after injury, such as fibrin, on human astrocyte behaviour and function are still missing. Here, we use fibrinogen-derived fibrin and fibrin-alginate-RGD (FAR) 3D hydrogel substrates to examine the influence on human iPSC-derived astrocyte behaviour and their direct conversion into neurons. Astrocytes develop complex morphologies in 3D-FAR hydrogels while are more proliferative and migratory in 3D-Fibrin. Interestingly, gene expression profile analysis revealed different reactive states of astrocytes in 3D-Fibrin and 3D-FAR, which persist over time. The highly inflammatory state in 3D-FAR is largely incompatible with direct neuronal reprogramming hampering the direct conversion even at early stages. Conversely, astrocytes in 3D-Fibrin hydrogels can readily convert into neurons, demonstrating a potent influence of how fibrin is presented on eliciting distinct astrocyte states with great relevance for fate conversion. Research highlightsO_LIFirst transcriptome of human astrocytes in 3D-Fibrin hydrogel and derivative C_LIO_LIFibrin-alginate-RGD (3D-FAR) hydrogel elicits high branching complexity along with exacerbated reactive signature in astrocytes C_LIO_LI3D-Fibrin hydrogels enable proliferation and migration of astrocytes C_LIO_LIDirect conversion of human iPSC-derived astrocytes into neurons in 3D-Fibrin hydrogel C_LI

neuroscience↗

bioRxiv2024

Pseudomonas aeruginosa faces a fitness trade-off between mucosal colonization and antibiotic tolerance during airway infections

Pseudomonas aeruginosa causes antibiotic-resilient acute and chronic pneumonia, but the mechanisms by which it adapts to the airway environment are poorly understood. Here, we investigated P. aeruginosa pathoadaptive mechanisms in tissue-engineered human airway organoids. Using transposon sequencing in situ, we decoded how P. aeruginosa survives on the mucosal surface during antibiotic treatment. Biofilm formation emerged as a major driver of P. aeruginosa colonization. Mutants that extensively produce biofilms on mucus show limited exploratory behavior, which limits nutrient access, slowing down their growth. Conversely, biofilm-dwelling P. aeruginosa better tolerate antibiotics via biophysical mechanisms. Finally, biofilms can shelter less-tolerant but more cytotoxic strains, thereby contributing to genotypic heterogeneity. P. aeruginosa must therefore adapt to conflicting physical and biological selective pressures to initiate chronic infections.

microbiology↗

bioRxiv2022

Pseudomonas aeruginosa contracts mucus to rapidly form biofilms in tissue-engineered human airways

The opportunistic pathogen Pseudomonas aeruginosa causes antibiotic-recalcitrant pneumonia by forming biofilms in the respiratory tract. Despite extensive in vitro experimentation, how P. aeruginosa forms biofilms at the airway mucosa is unresolved. To investigate the process of biofilm formation in realistic conditions, we developed AirGels: 3D, optically-accessible tissue-engineered human lung models that emulate the airway mucosal environment. AirGels recapitulate important factors that mediate host-pathogen interactions including mucus secretion, flow and air-liquid interface, while accommodating high resolution live microscopy. With AirGels, we investigated the contributions of mucus to P. aeruginosa biofilm biogenesis in in vivo-like conditions. We found that P. aeruginosa forms mucus-associated biofilms within hours by contracting luminal mucus early during colonization. Mucus contractions facilitates aggregation, thereby nucleating biofilms. We show that P. aeruginosa actively contracts mucus using retractile filaments called type IV pili. Our results therefore suggest that, while protecting epithelia, mucus constitutes a breeding ground for biofilms.

microbiology↗