Biology subjects

Hunt, N. K.

Publications and source records attributed to Hunt, N. K..

3 recordsLinked to original sources

bioRxiv2026

Gut microbiome-dependent IL-1 signaling is a mediator of ACVR1R206H-driven heterotopic ossification

Inflammatory diseases cause significant morbidity and mortality, but their pathobiology is often difficult to dissect due to complex genetic-environmental interactions. Genetic forms of heterotopic ossification, such as fibrodysplasia ossificans progressiva (FOP), reduce genetic variability, allowing careful dissection of non-genetic drivers of inflammation. While >95% of FOP patients harbor the ACVR1R206H mutation, patients exhibit significant variability in disease progression, suggesting a role of environmental drivers. Here, we identify the gut microbiome as a regulator of inflammation-driven HO in FOP. Metagenomic profiling of cohabitating FOP/unaffected sibling pairs revealed a pathogenic gut microbiome profile in FOP patients (Bray-Curtis, p < 0.05). In Pdgfr-Cre/Acvr1R206H (FOP) mice, gut microbiome ablation by antibiotics reduced spontaneous HO formation (47.4% reduction, p < 0.05) and reduced plasma IL-1 pathway activity. IL-1{beta} blockade in FOP mice suppressed trauma-induced HO formation. These findings identify a gut microbiome-IL-1-HO axis with modifiable targets for developing treatments for HO and related inflammatory conditions. One Sentence SummaryAntibiotic disruption of the gut microbiome reduces HO in FOP mice via an IL-1 mediated pathway.

immunology↗

bioRxiv2025

Modifications to the gut microbiome alter bone matrix proteomics and fracture toughness at the cellular scale

The gut microbiome can regulate the strength of bone matrix but the specific changes in matrix function and composition are not yet understood. Here we introduce micropillar splitting to determine the fracture toughness of matrix at the cellular scale in concert with proteomic analysis of bone matrix when the gut microbiome was altered by oral antibiotics (ampicillin+neomycin). Male mice were divided into four groups (n = 3-4/group): (1) Unaltered (no alteration), (2) Continuous (alteration from 4-24 weeks), (3) Delayed (alteration from 16-24 weeks) and (4) Reconstituted (alteration from 1-16 weeks following by reconstitution). Micropillars (5 {micro}m diameter) were fabricated using focused ion beam milling on femur cross-sections in regions of matrix formed either before or after changes in the microbiome (16 weeks) (n = 4/group). Proteomics was used to identify differences in matrix protein composition. Micropillar fracture toughness differed by group (p < 0.001) and region (p < 0.001). Fracture toughness in the Unaltered group (1.34 {+/-} 0.32 MPa{surd}m, mean {+/-} SD) was substantially greater than the Continuous group (0.95 {+/-} 0.20) and the Delayed group (0.90 {+/-} 0.21) but not different from the Reconstituted group (1.22 {+/-} 0.25). Bone matrix formed from 16-24 weeks of age had lower fracture toughness than matrix formed before 16 weeks of age in all groups. Notably, micropillar splitting was substantially more precise than whole bone testing; whole bone notched 3-point bending tests did not detect differences in fracture toughness. Proteomics identified 46 extracellular matrix proteins that were differentially abundant between groups, including decreased abundance of Periostin (q < 0.001) and Emilin-1 (q < 0.001) in groups with impaired bone matrix. These findings demonstrate that modifications to the gut microbiome lead to changes in bone matrix throughout cortical bone volume and establish micropillar splitting as a high-precision approach for characterizing matrix material properties. Plain Language SummaryThis study investigated the effect of the gut microbiome on the brittleness of bone as a material. We used a new technique for measuring the brittleness of bone that involves making microscopic pillars on the bone surface and splitting them down the middle to measure a material property called fracture toughness. Mice with altered gut microbiomes had bone with reduced fracture toughness (by 35-40%). Restoration of an altered gut microbiome for two months reversed the effects. The effect of the microbiome on bone occurred throughout the whole bone and was not limited to regions of the bone formed after a change in the gut microbiome.

bioengineering↗

bioRxiv2025

Design and Synthesis of Peptide-Polyester Conjugates for Cell-Mediated Scaffold Degradation

Biodegradable thermoplastic polyesters are promising biomaterials for tissue engineering due to their processability and mechanical properties. Polycaprolactone (PCL) is particularly attractive for load-bearing applications but does not degrade at the same rate as new tissue formation, which may compromise functional regeneration. This study presents a strategy for cell-mediated scaffold remodeling by incorporating a protease-cleavable peptide directly into the PCL backbone. Linear peptide-PCL conjugates were synthesized with poly(ethylene glycol) (PEG) spacers flanking the peptide to enhance protease access. A functional proteomics approach was used to identify a fast-degrading peptide sequence (Fast) selectively cleaved by multiple cell types. Conjugates containing Fast or its scrambled control (ScrFast) were combined with an RGDS-PCL conjugate and fabricated into scaffolds. Including Fast and ScrFast peptides did not impair cell adhesion to the scaffolds. Cy3 labeling enabled real-time quantification of scaffold degradation in the presence of collagenase or human mesenchymal stromal cells (hMSCs). Fast-PCL scaffolds degraded significantly faster than ScrFast-PCL in both conditions, demonstrating sequence-dependent and cell-directed resorption. Integrating protease-sensitive peptides into the polymer backbone is therefore an effective approach to fabricate solid scaffolds that degrade in response to cells. This platform can be adapted to couple cellular processes to scaffold remodeling to enhance tissue regeneration.

bioengineering↗