Biology subjects

Robertson, C. M.

Publications and source records attributed to Robertson, C. M..

5 recordsLinked to original sources

bioRxiv2026

A Multi-Institution Biobanking Pipeline for Primary Human Satellite Cells and Fibro-Adipogenic Progenitors

Satellite Cells (SCs) and Fibro-Adipogenic Progenitors (FAPs) are muscle-resident cell populations crucial for maintaining skeletal muscle homeostasis and coordinating regeneration after injuries. However, primary human SCs and FAPs are difficult to co-isolate, and their broad use in translational research has been limited by a lack of standardized biobanking protocols. Recently, we published a protocol for efficient co-isolation of SCs and FAPs from human skeletal muscle. Here, we extend those efforts to establish a comprehensive pipeline for the cryopreservation, cold-chain transport, and independent-site utilization of human SCs and FAPs. Cells taken through this pipeline maintained lineage-specific markers, including Pax7, MyoD and CD56 for SCs, and PDGFR and TE7 for FAPs, indicating retention of their pre-biobanking phenotype. Furthermore, SCs demonstrate robust myogenic differentiation capacity, and FAPs demonstrate both fibrogenic and adipogenic differentiation capacity post-transport. Finally, previously biobanked SCs were incorporated into in vitro 3D muscle constructs, demonstrating their utility for human-based New Approach Methodologies (NAMs). This framework for multi-site collaboration facilitates broader access to human primary muscle cells, which will improve the scalability and translatability of human-based NAMs for skeletal muscle research.

cell biology↗

bioRxiv2026

Type 2 diabetes mellitus exacerbates vaginal group B Streptococcus colonization via impaired mucosal cytokine response

Type 2 diabetes mellitus (T2D) is a metabolic disorder that confers increased risk of microbial infections, including those caused by the opportunistic pathogen group B Streptococcus (GBS). Asymptomatic GBS carriage in the vaginal tract is a notable reservoir for infection, but the impact of T2D on the vaginal mucosa and GBS colonization is not fully understood. We employed a diet-induced mouse model of T2D paired with vaginal GBS colonization to investigate the impact of diabetes on glucose availability, vaginal microbiome composition, and vaginal cytokine profiles at baseline and in response to GBS. We observed enhanced susceptibility of diabetic mice to GBS vaginal colonization and reproductive tract dissemination. Despite experiencing hyperglycemia, diabetic mice did not exhibit elevated glucose in the reproductive tract. Regarding the vaginal microbiota, diabetic mice had minimal compositional differences with decreased Mammaliicoccus being the only significant taxonomic variance. Vaginal cytokine profiling revealed consistently depressed cytokines in diabetic mice, beginning with KC at baseline and expanding to an array of eight pro-inflammatory cytokines post-GBS infection. Pairing cytokine observations with GBS colonization outcomes revealed a correlation between delayed vaginal IL-1 induction and persistent vaginal GBS, suggesting that vaginal cytokine deficiency may contribute to diabetic GBS vaginal colonization. Supplementation with intravaginal rIL-1 was sufficient to resolve GBS burden differences between diabetic mice and non-diabetic controls, confirming that deficient vaginal cytokine responses contribute to diabetic GBS vaginal persistence. These findings advance our understanding of diabetic vaginal mucosal susceptibility to pathogens and support the potential for immunological intervention in the susceptible diabetic population. IMPORTANCEPeople with T2D are more susceptible to microbial infections, but there is limited understanding of the mechanisms that drive this vulnerability. One possibility is that T2D enhances colonization of opportunistic pathogens, like GBS, in mucosal reservoirs as a precursor to infection. In this study, we used a diabetic mouse model to test whether diabetes alters the vaginal mucosa to promote GBS colonization. We found that increased vaginal GBS colonization in diabetic mice was not linked to tissue glucose availability or changes to the vaginal microbiome, but instead was associated with impaired vaginal immune responses. These findings provide a foundation for translational approaches to reduce GBS persistence and dissemination in at-risk individuals.

microbiology↗

bioRxiv2025

Human bladder organoids model urinary tract infection and bacteriophage therapy

Urinary tract infections (UTIs), primarily caused by uropathogenic Escherichia coli (UPEC), are among the most common antibiotic-resistant infections. Despite this, currently available preclinical UTI models lack the breadth of morphotypic and heterogenous cell populations of the human bladder, impairing the development of novel therapies. To address these limitations, we developed human bladder organoids derived from the bladder stem cells of multiple healthy donors which recapitulate cellular diversity of the urothelium. Using bulk and single cell RNA-sequencing, we characterized organoid responses to UPEC and phage exposure individually and in combination to model phage therapy. Although phage minimally affected the uroepithelium in the absence of infection, during UTI, phage treatment reduced bacterial burdens and dampened inflammatory responses and barrier disruption. Collectively, our findings highlight human bladder organoids as a tool for capturing conserved and individual-specific uroepithelial responses to infection while also providing preclinical efficacy and safety testing for therapeutic development.

microbiology↗

bioRxiv2023

Gestational diabetes augments group B Streptococcus perinatal infection through disruptions in maternal immunity and the vaginal microbiota

Group B Streptococcus (GBS) is a pervasive perinatal pathogen, yet factors driving GBS dissemination in utero are poorly defined. Gestational diabetes mellitus (GDM), a complication marked by dysregulated immunity and maternal microbial dysbiosis, increases risk for GBS perinatal disease. We interrogated host-pathogen dynamics in a novel murine GDM model of GBS colonization and perinatal transmission. GDM mice had greater GBS in utero dissemination and subsequently worse neonatal outcomes. Dual-RNA sequencing revealed differential GBS adaptation to the GDM reproductive tract, including a putative glycosyltransferase (yfhO), and altered host responses. GDM disruption of immunity included reduced uterine natural killer cell activation, impaired recruitment to placentae, and altered vaginal cytokines. Lastly, we observed distinct vaginal microbial taxa associated with GDM status and GBS invasive disease status. Our translational model of GBS perinatal transmission in GDM hosts recapitulates several clinical aspects and enables discovery of host and bacterial drivers of GBS perinatal disease.

microbiology↗

bioRxiv2023

Heterogeneity of the group B streptococcal type VII secretion system and influence on colonization of the female genital tract

Type VIIb secretion systems (T7SSb) in Gram-positive bacteria facilitate physiology, interbacterial competition, and/or virulence via EssC ATPase-driven secretion of small [a]-helical proteins and toxins. Recently, we characterized T7SSb in group B Streptococcus (GBS), a leading cause of infection in newborns and immunocompromised adults. GBS T7SS comprises four subtypes based on variation in the C-terminus of EssC and the repertoire of downstream effectors; however, the intra-species diversity of GBS T7SS and impact on GBS-host interactions remains unknown. Bioinformatic analysis indicates that GBS T7SS loci encode subtype-specific putative effectors, which have low inter-species and inter-subtype homology but contain similar domains/motifs and therefore may serve similar functions. We further identify orphaned GBS WXG100 proteins. Functionally, we show that GBS T7SS subtype I and III strains secrete EsxA in vitro and that in subtype I strain CJB111, esxA1 appears to be differentially transcribed from the T7SS operon. Further, we observe subtype-specific effects of GBS T7SS on host colonization, as subtype I but not subtype III T7SS promotes GBS vaginal persistence. Finally, we observe that T7SS subtypes I and II are the predominant subtypes in clinical GBS isolates. This study highlights the potential impact of T7SS heterogeneity on host-GBS interactions.

microbiology↗