Biology subjects

Drumm, M. L.

Publications and source records attributed to Drumm, M. L..

3 recordsLinked to original sources

bioRxiv2026

CFTR dysfunction in the intestinal epithelium is sufficient to promote pathogenic expansion of E. coli and enhanced barrier permeability in cystic fibrosis

Changes in the gut microbiome in cystic fibrosis (CF) are well characterized, yet their causes and downstream effects remain largely unknown. Well-documented alterations include reduced overall complexity (i.e. alpha diversity) of the gut microbiota and increased relative abundance of E. coli, which are associated with greater inflammation and shorter stature in infants. Previous results from our laboratory using a germ-free cystic fibrosis transmembrane conductance regulator (Cftr) mutant mouse model (CF mouse) demonstrated that the observed fecal microbiome dysbiosis is driven by mutated Cftr independent of factors such as diet or antibiotic treatment. We expand on these results in this report by using the defined 8-member community Altered Schaedler Flora (ASF) with and without E. coli, to show that E. coli is pathogenic in the context of the CF gut microbiome, resulting in increased intestinal permeability. We also show that Cftr deletion in intestinal epithelial cells alone, using a Villin-Cre targeted model, is sufficient to raise E. coli abundance in the fecal microbiome, increase intestinal permeability, and amplify the number of TH17 cells in the mesenteric lymph nodes. Together, our results demonstrate that the intestinal epithelium plays a dominant role in fecal microbiome alterations in CF and that the resultant dysbiosis contributes to CF pathogenesis.

microbiology↗

bioRxiv2026

Nonviral, ultrasound-triggered gene delivery platform via gas-core cationic nanobubbles

Despite their promise, lipid nanoparticle gene delivery systems have repeatedly failed clinical trials and struggle to achieve efficient, localized transfection in target tissues. The majority of endocytosed nanoparticles are degraded before nucleic acid release, and an inability to track particle distribution in vivo prevents validation of successful delivery. Alternatively, nanobubbles (NBs) are lipid-shelled, gas-core preclinical ultrasound contrast agents and stimuli-responsive drug delivery vehicles. Under varying acoustic pressures, NBs expand, contract, and burst, releasing cargo in an externally controlled, site-specific manner while scattering unique echoes for simultaneous ultrasound visualization. Here, we introduce a cationic nanobubble (CNB) formulation with a +42.3 mV zeta potential, 265 nm diameter, and 2.43x1011 NBs/mL concentration. CNBs produce stable ultrasound contrast, electrostatically load plasmid DNA onto their surface, and internalize into >99% of human prostate cancer cells within 15 minutes in vitro. CNBs remain brightly echogenic intracellularly and induce sonication-dependent expression of green fluorescent protein (GFP). In vivo, CNBs generate contrast in mouse livers for 50 minutes after intravenous administration. Therapeutic ultrasound stimulation over the liver causes a sharp reduction in ultrasound contrast, visualizing localized cavitation in the target organ and inducing a 2.5-fold increase in anti-GFP mean fluorescence intensity relative to the untransfected control. Importantly, no GFP expression is observed without ultrasound stimulation, supporting a mechanism for selective and site-specific gene delivery. This study presents a highly stable CNB capable of efficient DNA loading and ultrasound-dependent gene expression. These results provide a foundation for the future development of CNB platforms to advance image-guided, ultrasound-triggered gene therapy.

bioengineering↗

bioRxiv2026

Correction of multiple splicing mutations associated with CFTR exon 18 using a single exon-specific U1 snRNA

Splice site mutations represent a major class of pathogenic mutations in many diseases, as these changes disrupt normal splicing leading to gene expression changes. Cystic fibrosis (CF) results from mutations to the cystic fibrosis transmembrane conductance regulator (CFTR) gene that encodes an essential ion channel. Approximately 13% of the over 2,100 known CFTR mutations disrupt 3 or 5 splice sites and are predicted to cause splicing defects. Because each splicing mutation is rare, developing individualized therapies to treat each one is financially challenging. Exon specific U1 snRNA (ExSpeU1) targets the non-conserved intronic region downstream the 5 splice site (ss) to rescue exon skipping. Because this approach is exon-rather than mutation-specific, a single agent can potentially rescue multiple mutations. In this study, we have developed a platform to systematically classify all patient variants associated with an exon that are predicted to affect splicing and then determine their rescue potential using ExSpeU1. Here we report the results of these studies. Our minigene reporter study shows that 7 of 10 exon 18 variants resulted in exon skipping. Four mutations at the 3 and 5 ss were rescued at least partially using a single ExSpeU1. Using a luciferase reporter, we observe that the splicing rescue is reflected at the protein level. Lastly, we demonstrate exon-targeting ExSpeU1s can also rescue 3 and 5 ss mutations. Overall, this study exemplifies the power of our platform to screen and rescue multiple patient-derived splicing mutations using a single agent.

genetics↗