Biology subjects

Sheehan, K.

Publications and source records attributed to Sheehan, K..

3 recordsLinked to original sources

bioRxiv2025

Kinetics of de novo Bone and Bone Marrow Niche Formation with Hybrid Click Cryogels

Successful hematopoietic stem cell transplantation (HSCT) critically depends on efficient T cell recovery, which is limited by compromised bone marrow niches following irradiation. While various factors influence the regeneration of bone and bone marrow niches, the dynamics of this process remain elusive. Here, we explore the kinetics of de novo bone and bone marrow development under varying BMP-2 doses, host immune status, and biological sex, using a cryogel of covalently crosslinked alginate and gelatin releasing BMP-2. Bone formation was monitored by ultrasonography and microcomputed tomography (microCT) analysis, while histological analysis provided insights into the relation between mineralized tissue and bone marrow formation. Bone developed within 2-4 weeks, resulting in cortical bone around the cryogels, and a trabecular bone network with hematopoietic tissue within the cryogels. Higher BMP-2 doses significantly accelerated mineralization kinetics and doubled the resident hematopoietic stem cell population. Notably, immunocompromised status delayed niche development by two weeks and reduced hematopoietic stem cells fourfold. We also found that female mice exhibited enhanced niche formation compared to males under the identical conditions. These findings provide insights into the factors that govern the spatiotemporal regulation of bone and bone marrow niche development and establish this hybrid click cryogel system as a promising platform for improving T cell reconstitution in HSCT patients.

bioengineering↗

bioRxiv2024

Androgen receptor interactions provide insight into steroid mediated metabolic shifts in endocrine resistant breast cancer.

PurposeAromatase Inhibitors (AI) are standard therapy for hormone receptor positive breast cancers in post-menopausal patients. Disease recurrence is common and previous studies suggest that the altered steroid environment may be a driver of resistance. Using label-free mass-spectrometry we explored the unique androgen receptor (AR) interactome that supervenes in AI resistant breast cancer and the associated hyperandrogenic environment. Experimental DesignAR expression was evaluated in a primary breast cancer tissue-microarray (n=875) with nuclear and cytoplasmic localization quantified. Liquid-chromatography tandem mass-spectrometry (LC-MS/MS) analysis was utilized to identify proteins interacting with the AR in models of AI-resistance. Validation was carried out by co-immunoprecipitation and co-localisation studies. Live-cell imaging, Seahorse MitoStress Assays and flow cytometry were used to quantify changes in mitochondria and cell metabolism arising in models of AI-resistance. ResultsUtilising digital pathology we detected that abundant cytoplasmic AR protein was associated with poor survival only in the post-menopausal cohort, and most significantly, in the therapy-refractory Luminal B subtype (p=0.0085). Models of AI-resistance and androgen excess highlight diffuse AR localisation throughout the cytoplasm and nucleus accompanied by increased mitochondrial mass and membrane potential, and increased oxidative phosphorylation and glycolysis. Exploration of the AR protein interactome identified G3BP1, SLIRP, and IGFBP5 as AR protein partners which are associated with stress, adaptive metabolic response and estrogen receptor repression. ConclusionsThe findings of this study highlight the prognostic potential of cytoplasmic AR immunoreactivity in specific breast cancer subtypes and uncover novel extra-nuclear AR protein interactions that may mediate metabolic adaptations during the development of endocrine-resistance.

cancer biology↗

bioRxiv2024

Altered inflammatory state and mitochondrial function identified by transcriptomics in paediatric congenital heart patients prior to surgical repair

ObjectiveCongenital heart disease (CHD) remains the most common birth defect, with surgical intervention required in complex cases. Right ventricle (RV) function is known to be a major predictor in sustained cardiac health in these patients, thus by elucidating divergent profiles between CHD and control through tissue analysis this study aims to identify new avenues of investigation into the mechanisms surrounding reduced RV function. Approach & ResultsTranscriptomic profiling, in silico cellular deconvolution and functional network analysis was conducted on RV biopsies obtained from CHD and control paedatric patients. Analysis identified an increase in mitochondrial dysfunction genes RPPH1 and RMPR (padj = 4.67E-132, 2.23E-107, respectively), Cytotoxic T cell markers CD8a, LAGE3 and CD49a (p = 0.0006, p < 0.0001, p = 0.0118, respectively) and proinflammatory marker Caspase1 (p=0.0055) in CHD compared to control. Gene set enrichment identified mitochondrial dysfunctional pathways, predominately changes to the oxidative phosphorylation processes. Negative regulation of mitochondrial functions and metabolism was identified in functional network analysis, with dysregulation of mitochondrial complex formation. Histological analysis confirmed an increase in cellular bodies with the CHD RV tissue, and positive staining for both CD45 and CD8 in CHD RV tissue, which was absent in control. Deconvolution of bulk RNAseq data suggests a reduction in CD4+ T cells (p = 0.0067) and an increase in CD8+ T cells (p = 0.0223). Network analysis identified positive regulation of the immune system and cytokine signalling clusters within the inflammation functional network as were lymphocyte activation and leukocyte differentiation. ConclusionsUtilizing RV tissue from paediatric patients undergoing CHD cardiac surgery this study identifies dysfunctional mitochondrial pathways and an increase in inflammatory T cell presence prior to reparative surgery.

immunology↗