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Pennington, S. H.

Publications and source records attributed to Pennington, S. H..

6 recordsLinked to original sources
bioRxiv2026

Bloodstream-associated Salmonella Typhimurium and Enteritidis iNTS pathovariants hyper-replicate in human macrophages

Invasive non-typhoidal Salmonella (iNTS) are a major cause of bloodstream infections in sub-Saharan Africa, yet the host-pathogen interaction mechanisms remain poorly understood. Here, we developed and optimised a human macrophage infection model based on PMA-differentiated THP-1 cells to investigate infection dynamics of clinically relevant Salmonella Typhimurium and Salmonella Enteritidis strains. We compared intracellular survival and replication of gastroenteritis-associated and bloodstream-associated pathovariants, including S. Typhimurium ST313 Lineage 2, the novel S. Typhimurium ST313 Lineage 3 and the understudied S. Enteritidis Central/Eastern African (CEAC) clades. Our results reveal that the CEAC S. Enteritidis and ST313 S. Typhimurium iNTS pathovariants hyper-replicate within host cells, compared to global epidemic isolates. The cellular model achieved robust pro-inflammatory polarisation of human macrophages, while revealing limitations in modelling macrophage plasticity. Overall, this work defines clear differences in intracellular behaviour of Salmonella pathovariants and establishes a robust experimental framework for future studies on invasive disease pathogenesis and therapeutic interventions that target iNTS bacteria.

microbiology↗
bioRxiv2025

Dynamic Culture Improves the Predictive Power of Bronchial and Alveolar Airway Models of SARS-CoV-2 Infection

Human in vitro lung models represent advanced tools for studying respiratory infections, particularly those caused by emerging respiratory pathogens. Despite scientific advances, vaccine and therapeutics pre-clinical development has yet to fully adopt human-relevant testing platforms due in part to a lack of validation. In this study, we characterised how static and dynamic flow culture conditions influence microphysiological systems (MPS) generated using primary bronchial and alveolar epithelial cells. We assessed epithelial structure, functional differentiation, and infection dynamics. This study represents the first direct comparison of how dynamic flow and endothelial co-culture influence viral tropism, replication kinetics, and host responses across anatomically distinct regions of the respiratory tract in vitro. Dynamic flow promoted formation of more physiologically relevant tissue architecture, pseudostratified bronchial epithelium and alveolar sac-like structures, with enhanced epithelial differentiation and retention of region-specific cell phenotypes at the transcriptomic level. Both static and dynamic flow models demonstrated responsiveness to inflammatory stimuli (poly(I:C), LPS), producing distinct, tissue-specific cytokine profiles and supporting infection with multiple SARS-CoV- 2 variants. Differences in infection efficiency, viral replication, and host gene expression were observed between variants, with dynamic flow models offering enhanced sensitivity and resolution. In alveolar tissues, dynamic flow increased infection efficiency and reduced variability, enabling more robust and consistent transcriptional responses. This facilitated the identification of interferon signalling pathways as key targets of the host response. Among the variants tested, Delta induced the most extensive tissue damage and strongest transcriptional response, whereas Omicron BA.5 exhibited greater infectivity in alveolar models compared to earlier variants. Our findings demonstrate that dynamic flow MPS more closely replicate human lung tissue architecture and cellular diversity, while also enhancing the predictive power and clinical relevance of airway models for ex vivo studies of SARS-CoV-2 infection. These improvements strengthen the reliability of data generated for the study of host-pathogen interaction studies and support the use of dynamic systems for evaluating novel anti-infectives, immunomodulators, and functional characterisation of immune sera generated by next-generation vaccines. Collectively, our results highlight the value of integrating dynamic in vitro models into preclinical pipelines for emerging respiratory pathogens.

microbiology↗
bioRxiv2024

An Accessible 3D HepG2/C3A Liver Spheroid Model Supporting the Complete Intrahepatocytic Lifecycle of Plasmodium falciparum

Current liver-stage Plasmodium falciparum models are complex, expensive, and largely inaccessible, hindering research progress. Here, we show that a 3D liver spheroid model grown from immortalized HepG2/C3A cells supports the complete intrahepatocytic lifecycle of P. falciparum. Our results demonstrate sporozoite infection, development of exoerythrocytic forms, and breakthrough infection into erythrocytes. The 3D-grown spheroid hepatocytes are structurally and functionally polarised, displaying enhanced albumin and urea production and increased expression of key metabolic enzymes, mimicking in vivo conditions - relative to 2D cultures. This accessible, reproducible model lowers barriers to malaria research, promoting advancements in fundamental biology and translational research.

microbiology↗
bioRxiv2022

Lack of antiviral activity of probenecid in Vero E6 cells and Syrian golden hamsters: a need for better understanding of inter-lab differences in preclinical assays.

Antiviral interventions are urgently required to support vaccination programmes and reduce the global burden of COVID-19. Prior to initiation of large-scale clinical trials, robust preclinical data in support of candidate plausibility are required. The speed at which preclinical models have been developed during the pandemic are unprecedented but there is a vital need for standardisation and assessment of the Critical Quality Attributes. This work provides cross-validation for the recent report demonstrating potent antiviral activity of probenecid against SARS-CoV-2 in preclinical models (1). Vero E6 cells were pre-incubated with probenecid, across a 7-point concentration range, or control media for 2 hours before infection with SARS-CoV-2 (SARS-CoV-2/Human/Liverpool/REMRQ0001/2020, Pango B; MOI 0.05). Probenecid or control media was then reapplied and plates incubated for 48 hours. Cells were fixed with 4% v/v paraformaldehyde, stained with crystal violet and cytopathic activity quantified by spectrophotometry at 590 nm. Syrian golden hamsters (n=5 per group) were intranasally inoculated with virus (SARS-CoV-2 Delta variant B.1.617.2; 103 PFU/hamster) for 24 hours prior to treatment. Hamsters were treated with probenecid or vehicle for 4 doses. Hamsters were ethically euthanised before quantification of total and sub-genomic pulmonary viral RNAs. No inhibition of cytopathic activity was observed for probenecid at any concentration in Vero E6 cells. Furthermore, no reduction in either total or sub-genomic RNA was observed in terminal lung samples from hamsters on day 3 (P > 0.05). Body weight of uninfected hamsters remained stable throughout the course of the experiment whereas both probenecid- (6 - 9% over 3 days) and vehicle-treated (5 - 10% over 3 days) infected hamsters lost body weight which was comparable in magnitude (P > 0.5). The presented data do not support probenecid as a SARS-CoV-2 antiviral. These data do not support use of probenecid in COVID-19 and further analysis is required prior to initiation of clinical trials to investigate the potential utility of this drug.

pharmacology and toxicology↗
bioRxiv2020

Remdesivir-Ivermectin combination displays synergistic interaction with improved in vitro antiviral activity against SARS-CoV-2

A key element for the prevention and management of COVID-19 is the development of effective therapeutics. Drug combination strategies of repurposed drugs offer several advantages over monotherapies, including the potential to achieve greater efficacy, the potential to increase the therapeutic index of drugs and the potential to reduce the emergence of drug resistance. Here, we report on the in vitro synergistic interaction between two FDA approved drugs, remdesivir and ivermectin resulting in enhanced antiviral activity against SARS-CoV-2. These findings warrant further investigations into the clinical potential of this combination, together with studies to define the underlying mechanism.

microbiology↗