Biology subjects

Low, R.

Publications and source records attributed to Low, R..

7 recordsLinked to original sources

bioRxiv2026

TGFB1-Engineered Induced Mesenchymal Stromal Cells Exhibit High Immunomodulatory Potency and Durably Reprogram Synovial Macrophages in Osteoarthritis

Clinical translation of mesenchymal stromal cell (MSC) therapies derived from primary tissue sources is limited by manufacturing inconsistencies driven by donor-to-donor variability, which reduces predictability of clinical response. Induced pluripotent stem cell (iPSC)-derived MSCs (iMSCs) offer a promising donor-independent, clonal alternative strategy that is also more amenable to engineering, but whether engineered iMSCs reproduce the potency attributes of primary MSCs remains unclear. Here, we benchmarked a doxycycline-inducible, hTERT-immortalized iMSC line engineered to overexpress TGFB1 (TGFB1-iMSCs), a key regulator of macrophage polarization, against multiple adipose tissue-derived MSC (MSC(AT)) donors across predefined immunomodulatory and angiogenic potency attributes. TGFB1-iMSCs were smaller and more circular with comparable or higher proliferative rates than primary MSC(AT) donors. Interestingly, they had a distinct angiogenic signature (EDIL3, EDN1, PDGFA), and nine differentially expressed microRNAs were predicted to target secretory trafficking and growth factor receptor signalling. Functionally, however, TGFB1-iMSCs secreted less VEGF and showed intermediate HUVEC tube formation, but matched or exceeded all primary MSC(AT) donors in a monocyte-macrophage transwell immunomodulatory assay. Notably, in a murine destabilization of the medial meniscus (DMM) model of post-traumatic osteoarthritis, a single intra-articular injection of TGFB1-iMSCs, but not MSC(AT), reduced total synovial macrophage numbers and lowered the MHCII/CD206 ratio at eight weeks, although it did not reduce cartilage degeneration, synovitis, or fibrosis. Together, these findings show that TGFB1-engineered iMSCs have a macrophage-directed potency profile distinct from that of primary MSC(AT). Immortalized iMSCs therefore provide a reproducible platform for mechanistically dissecting engineered MSC potency and its effects on the immune environment.

immunology↗

bioRxiv2025

NTX250: A Modular mRNA-Based Immunotherapy Platform for HPV-Associated Cancers with Broad Applicability.

Infection with high-risk human papillomavirus (HPV) is a key driver of multiple HPV-associated malignancies, including cervical intraepithelial neoplasia (CIN), oropharyngeal, head and neck, and anogenital cancers. Despite the high efficacy of prophylactic HPV vaccines, a substantial population remains at ongoing risk due to issues related to vaccine accessibility, awareness, or personal choice. Current treatments, such as the loop electrosurgical excision procedure (LEEP), address lesions but do not eliminate persistent HPV infection and are associated with potential complications. Moreover, individuals treated for HPV-related disease are at increased risk for subsequent HPV-associated malignancies. These factors underscore an urgent need for effective, non-invasive therapeutic strategies capable of targeting and eradicating persistent HPV infections. Here we introduce NTX250, an innovative mRNA-based therapeutic platform designed to deliver HPV type 16 (HPV16) E6-E7 antigens, combined with immunomodulators human interleukin-12 (IL-12) p70 and engineered human LIGHT (LIGHT). The mRNAs are co-delivered via lipid and ionizable peptoid nanoparticles referred to as Nutshell formulation for intralesional administration. Our preclinical evaluation demonstrates that localized delivery of NTX250 in HPV16-transformed tumor-bearing models results in complete tumor regression and the induction of durable, antigen-specific immune memory. Moreover, this modular mRNA nanoparticle approach combining tumor-specific antigens and immunomodulators is adaptable beyond HPV, with potential applications targeting neoepitopes or other tumor-associated antigens, thus offering a versatile platform for immunotherapy across a broad range of indications. These findings highlight the potential of this strategy as a broadly applicable, non-surgical immunotherapeutic capable of inducing robust and specific anti-tumor responses.

immunology↗

bioRxiv2025

Mesenchymal Stromal Cells Immunosuppress Osteoarthritis Synovial Fluid Tolerized Monocytes via IL-6

BackgroundMesenchymal stromal cell (MSC) interactions with monocytes/macrophages are central to their therapeutic effects in knee osteoarthritis (KOA); however, mechanisms of these interactions are not fully understood. HypothesisWe hypothesize that MSC soluble factors, particularly interleukin-6 (IL-6) and C-C motif chemokine ligand (CCL2) modulate monocytes in KOA environment. MethodsUsing healthy donor CD14+ monocytes exposed to KOA synovial fluid (SF) in the presence or absence of marrow-derived MSC(M) directly or conditioned medium (CM), we evaluated cell surface markers and signaling via signal transducer and activator of transcription (STAT3), nuclear factor kappa-light-chain-enhancer of activated B (NF-{kappa}B) and c-Jun Terminal Kinase (JNK); functional responses were measured by secretion of tumor necrosis factor (TNF) and IL-1, and by phagocytosis of pHrodo Red E-coli. ResultsCD14+ monocytes demonstrated a mixed phenotype in KOA SF with increased CD163, CD206 and unchanged HLA-DR, CD86 marker expression. This was accompanied by activated STAT3, JNK and NF-{kappa}B signaling. TNF and IL-1 secreted levels were unchanged, but phagocytosis was impaired, indicative of a net dysfunctional repair phenotype and functionality. CD14+ monocytes in KOA SF were hyporesponsive to additional lipopolysaccharide re-challenge, based on TNF and IL-1 secretion. Addition of MSC(M) to KOA SF programmed CD14+ monocytes resolved the dysfunctional phenotype and functionality, with significant increases in CD163, CD206; significant reductions in HLA-DR and CD86 expression; this was accompanied by significantly increased activated STAT3, and decreased activated JNK and NF-{kappa}B. TNF and IL-1 secretion were also significantly reduced, and phagocytic capacity restored. Blocking IL-6, or to a lesser extent, CCL2, partially abrogated MSC(M) soluble factor effects. MSC(M) experienced apoptosis in KOA SF; however, apoptotic bodies did not fully recapitulate MSC(M) soluble factor effects. ConclusionIL-6, CCL2, other soluble factors and apoptotic bodies from MSC(M) secretome mitigate the dysfunctional effects of KOA SF on CD14+ monocytes resulting in immunosuppressed phenotype and functionality.

immunology↗

bioRxiv2021

Analysis of wild plant pathogen populations reveals a signal of adaptation in genes evolving for survival in agriculture in the beet rust pathogen (Uromyces beticola)

Improvements in crop resistance to pathogens can reduce yield losses and address global malnourishment today. Gene-for-gene -type interactions can identify new sources of resistance but genetic resistance is often short lived. Ultimately an understanding of how pathogens rapidly adapt will allow us to both increase resistance gene durability and more effectively target chemical treatments. Until recently all agricultural pathogens were living on wild hosts. To understand crop pathogen evolution, we compared genetic diversity in agricultural and wild populations. Wild reservoirs may be the source of emergent pathogen lineages, but here we outline a strategy for comparison of wild and agricultural pathogen populations to highlight genes adapting to agriculture. To address this, we have selected and developed the beet rust system (Beta vulgaris, Uromyces beticola, respectively) as our wild-agricultural model. Our hypothesis is that pathogen adaptation to agricultural crops will be evident as divergence in comparisons of wild and agricultural plant pathogen populations. We sampled isolates in both the wild and agriculture, sequenced and assembled and annotated a large fungal genome and analysed genetic diversity in 42 re-sequenced rust isolates. We found population differentiation between isolates in the wild compared to a predominantly agricultural group. Fungal effector genes are co-evolving with host resistance and are important for successful colonisation. We predicted (and found) that these exhibit a greater signal of diversification and adaptation and more importantly displayed increased wild agricultural divergence. Finding a signal of adaptation in these genes highlights this as an important strategy to identify genes which are key to pathogen success, that analysis of agricultural isolates alone cannot. Author SummaryAs quickly as we develop new strategies for crop defence, pathogens evolve to circumvent them. Novel crop pathogen strains emerge periodically and sweep through the agricultural system. However, because of the (often) clonal nature of these crop pathogens it is difficult to identify the trait that is key to their success. In other words, if there is a trait that is key for success in agriculture, all agricultural isolates will have it (or die without it). What we need is a case and control system where we identify genes important to pathogen success in agricultural by comparing them to pathogens that live in the wild. Here we exemplify this strategy by focussing on genes already known to specifically adapt for the successful colonisation of the host, the fungal effector genes. We find that these genes appear to be evolving quickly and that they are more different between the wild and agriculture than other non-effector genes. These differences between wild and agricultural pathogens suggest we are observing adaptation to agriculture. We do this work in the sugar beet rust system because of its tractability to sample but this understanding about how to identify genetic variation that is key to pathogen success in agriculture is applicable to crop systems where pathogen reservoirs exist as well as other pathogen reservoir systems (e.g. zoonoses).

evolutionary biology↗

bioRxiv2021

Informing shigellosis prevention and control through pathogen genomics

Shigella spp. are the leading bacterial cause of severe childhood diarrhoea in low- and middle-income countries (LMIC), are increasingly antimicrobial resistant and have no licensed vaccine. We performed genomic analyses of 1246 systematically collected shigellae from seven LMIC to inform control and identify factors that could limit the effectiveness of current approaches. We found that S. sonnei contributes [≥]20-fold more disease than other Shigella species relative to its genomic diversity and highlight existing diversity and adaptative capacity among S. flexneri that may generate vaccine escape variants in <6 months. Furthermore, we show convergent evolution of resistance against the current recommended antimicrobial among shigellae. This demonstrates the urgent need to integrate existing genomic diversity into vaccine and treatment plans for Shigella, and other pathogens.

microbiology↗

bioRxiv2020

An accessible, efficient and global approach for the large-scale sequencing of bacterial genomes

We have developed an efficient and inexpensive pipeline for streamlining large-scale collection and genome sequencing of bacterial isolates. Evaluation of this method involved a worldwide research collaboration focused on the model organism Salmonella enterica, the 10KSG consortium. By optimising a logistics pipeline that collected isolates as thermolysates, permitting shipment in ambient conditions, the project assembled a diverse collection of 10,419 clinical and environmental isolates from low- and middle-income countries in less than one year. The bacteria were obtained from 51 countries/territories dating from 1949 to 2017, with a focus on Africa and Latin-America. All isolates were collected in barcoded tubes and genome sequenced using an optimised DNA extraction method and the LITE pipeline for library construction. After Illumina sequencing, the total reagent cost was less than USD$10 per genome. Our method can be applied to genome-sequence other large bacterial collections at a relatively low cost, within a limited timeframe, to support global collaborations.

microbiology↗

bioRxiv2019

Genomic and phylogenetic analysis of Salmonella Typhimurium and its monophasic variants responsible for invasive endemic infections in Colombia

Salmonellosis is an endemic human infection, associated with both sporadic cases and outbreaks throughout Colombia. Typhimurium is the most common Colombian serovar of Salmonella enterica, responsible for 32.5% of the Salmonella infections. Whole genome sequencing (WGS) is being used increasingly in Europe and the USA to study the epidemiology of Salmonella, but there has not yet been a WGS-based analysis of Salmonella associated with bloodstream infection in Colombia. Here, we analysed 209 genome sequences of Colombian S. Typhimurium and monophasic S. 4,[5],12:i:-isolates from Colombia from 1999 to 2017. We used a core genome-based maximum likelihood tree to define seven distinct clusters which were predominantly Sequence Type (ST) 19 isolates. We also identified the first ST313 and monophasic ST34 isolates to be reported in Colombia. The history of each cluster was reconstructed with a Bayesian tree to reveal a timeline of evolution. Cluster 7 was closely related to European multidrug-resistant (MDR) DT104. Cluster 4 became the dominant variant of Salmonella in 2016, and resistance to nalidixic acid was associated with a plasmid-encoded qnrB19 gene. Our findings suggest multiple transfers of S. Typhimurium between Europe and Colombia.\n\nAuthor summaryThe large-scale genome sequencing of Salmonella Typhimurium and monophasic Salmonella 4,[5],12:i:-involved bloodstream isolates from Colombia. The two serovars were responsible for about 1/3 of Salmonella infections in Colombia in the past 20 years. To identify the population structure we used Whole Genome Sequencing, performed in silico sequence typing, obtained phylogenetic trees, inferred the evolutionary history, detected the plasmids and prophages, and associated the antibiotic resistance (AMR) genotype with phenotype. Different clusters showed temporal replacement. The Colombian sequence type 313 was distinct from African lineages due to the absence of a key virulence-related gene, bstA. One of the Colombian clusters is likely to belong to the global epidemic of DT104, according to the evolutionary history and the AMR profile. The most common cluster in recent years was resistant to nalidixic acid and carried a plasmid-mediated antibiotic resistant gene qnrB19. Our findings will inform the ongoing efforts to combat Salmonellosis by Colombian public health departments.

genomics↗