Biology subjects

Carr, C.

Publications and source records attributed to Carr, C..

8 recordsLinked to original sources

bioRxiv2026

Emergence and antigenic characterisation of influenza A(H3N2) viruses with hemagglutinin substitutions N158K and K189R during the 2024/25 influenza season

BackgroundSeasonal human influenza viruses can escape from antibody-mediated neutralization when amino acid changes occur in the hemagglutinin protein. Routine surveillance identified circulation of an A(H3N2) virus variant in the Netherlands with amino acid substitutions at hemagglutinin positions 158 and 189. These amino acid positions were previously responsible for antigenic change of influenza A(H3N2) viruses and potentially lead to escape of this variant from vaccine-mediated immunity. AimTo characterize the emergence and antigenic properties of N158K and K189R double substitution virus variants. MethodsWe analyzed the geographical and temporal dynamics of the double-substitution variant using a phylogeographic approach and used hemagglutination inhibition assays and antigenic cartography methods to map its antigenic properties. ResultsA(H3N2) viruses carrying K189R were first detected in Guatemala in June 2024, before subsequently gaining the N158K substitution, which was intially detected in Colombia in November 2024, followed by detection in the Netherlands in December 2024. However, detections within Europe remained almost entirely confined to the Netherlands. The proportion of viruses carrying the N158K and K189R substitutions increased to 16% - 24% per collection week of sequenced Dutch viruses during the peak of the epidemic of the 2024-2025 respiratory season. Antigenic characterization of viruses with N158K and K189R substitutions indicated that these are antigenically distinct from the A(H3N2) components of 2025-2026 Northern Hemisphere vaccines, showing 8-192-fold reduction in hemagglutination inhibition titers with antisera against the vaccine strain compared to antisera against the homologous virus. ConclusionsInfluenza A(H3N2) viruses with N158K and K189R escaped recognition by antibodies raised against the 2024-2025 and 2025/2026 Northern Hemipshere vaccine strains in hemagglutination inhibition assays. These variants circulated widely in the Netherlands during the 2024-2025 influenza season, raising concerns about reduced vaccine-mediated protection if such variants would spread more broadly during 2025-2026 Northern Hemipshere season.

microbiology↗

bioRxiv2025

TAp73 mediates anti-tumor immunity through regulation of lipid metabolism in the lung tumor microenvironment

While immunotherapy has become the standard of care for lung adenocarcinoma (LUAD) patients without actionable genomic alterations, only a subset of patients benefits from a long-lasting response to immunotherapy. Activation of p53-related signals has emerged as a potential mediator of the lung tumor microenvironment (TME). Given that mutant-p53 interacts with p73 extensively and TAp73-deficient mice develop LUAD, we engineered a mouse model with conditional deletion of TAp73 to understand the interactions of the p53 family in the TME and in metabolic pathways that impact anti-tumor immunity. We demonstrated that TAp73 exerts a tumor-suppressive role in KrasG12D-driven LUAD by regulating lipid metabolism in the TME. We identified a TAp73-driven transcriptional signature involving genes in the arachidonic acid metabolism pathway operational in tumor-associated macrophages that favors T-cell activation and thus anti-tumor immunity. Similar transcriptional changes are seen in macrophages from LUAD patients with p53 mutations and in association with response to immunotherapy. SIGNIFICANCEThere is a need to understand how the LUAD TME impacts patient response to immunotherapy. We identified a transcriptional program enacted by TAp73 in tumor alveolar macrophages that supports T-cell activation. Transcriptional and metabolomic data from LUAD patients supports the relevance of this program in response to immune checkpoint inhibition.

cancer biology↗

bioRxiv2025

Post-infection pig and ferret antisera show similar antigenic profiles for human influenza A(H1N1pdm09) viruses

BackgroundMonitoring antigenic drift in human influenza A viruses is essential for vaccine strain selection and ensuring protection against circulating strains. Antigenic drift is traditionally assessed using ferret antisera, which provide monospecific responses, and human vaccinee sera, which reflect exposure to multiple antigens. In this study we evaluated the pig as an alternative source of antisera to study antigenic drift compared to immune responses in ferrets and humans. We included seasonal influenza A(H1N1pdm09) human viruses that had shown different antigenic characteristics when using ferret or human antisera. MethodsPairs of pigs were inoculated with six human A(H1N1)pdm09 viruses circulating between 2019 and 2023, a period of marked antigenic drift. Pig and ferret antisera were analysed by hemagglutination inhibition (HI) and virus neutralization (VN) assays. ResultsPigs were successfully infected with all strains, shedding virus and producing antibody responses, confirming their susceptibility to human influenza A viruses. Antigenic reactivity of pig antisera was qualitatively comparable to ferret antisera in both HI and VN assays, although maximum homologous antibody titres were significantly higher in ferrets. The antisera raised against viruses in circulation in 2019 and before, exempified by A/Guangdong-Maonan/SWL1536/2019, clade 5a.1, were clearly differentiated by both ferret and pig antisera from those in clade 5a.2 and its derivatives that became predominant. ConclusionsFerrets and pigs showed comparable responses and both distinguished clade 5a.1 from clade 5a.2. However, neither model recognised antigenically drifted variants from 2019-2022, including subclades 5a.2-C, 5a.2a-C.1/C.1.9, and .5a.2a.1-C.1.1/D, which were distinguishable using human post-vaccination antisera.

immunology↗

bioRxiv2025

Endothelial cell-intrinsic NOD2 signaling regulates the intestinal immune response through the generation of effector and memory T cells.

Crohns disease (CD) is marked by vascular endothelial dysfunction and aberrant T cell immunity in the gastrointestinal tract. However, mechanistic understanding is lacking of how CD-associated gene variants, particularly those that compromise NOD2 function, impact the intestinal vascular endothelium and orchestration of T cell immunity. Here, we find that NOD2, when triggered by its ligand, muramyl dipeptide, is unique among pattern recognition receptors in its ability to induce endothelial cell expression of chemokines and immune adhesion molecules. Consequently, NOD2 signaling promoted T cell homing specifically to gut-associated lymphoid tissue during intestinal infection. Endothelial cell-specific deletion of Nod2 resulted in fewer effector and memory T cells in the small intestine, impacting the hosts ability to clear secondary infection. Together, our findings suggest that vascular endothelial cell expression of NOD2 coordinates intestinal immune responses, and that CD-associated loss of NOD2 function promotes aberrant inflammation due to alterations in the magnitude and specificity of host defense within the intestine.

immunology↗

bioRxiv2025

Endothelial Slit2 guides the Robo1-positive sympathetic innervation during heart development

Axon guidance cues direct nerves in the heart during development, disease and regeneration. These cues determine cardiac innervation patterning by regulating the balance between chemo-attraction and chemo-repulsion. However, the role of one of the most crucial ligand-receptor combinations among axon guidance molecules, the Slit chemo-active ligands and their Roundabout (Robo) transmembrane receptors, remains unknown during cardiac innervation patterning. To test if Slit-Robo signalling is important for cardiac innervation guidance, we analysed Slit and Robo mouse knock-outs. Constitutive Slit2-/- ventricles showed significantly reduced innervation, while Slit3-/- hearts showed temporary increased levels of innervation compared to wild-type littermate controls. Whereas innervation was not affected in Robo2-/- mice, the phenotype seen in Slit2-/- ventricles was recapitulated in Robo1-/- mice. Detailed expression analysis identified expression of Slit2 ligand in the endothelium of the coronary vessels, while Slit3 was highly present in the coronary smooth muscle wall and in the innervation. Both the Robo1 and Robo2 receptors were present in the nerves and at low levels in the vessels. Knocking out Slit2 specifically in the endothelium recapitulated the defects seen in the constitutive Slit2-/- hearts. Ex vivo axon guidance cultures showed that attraction of axons extending from the ganglia was strongly reduced in ventricles with absence of endothelial Slit2 compared to wild-type controls. In absence of endothelial Slit2, adult mice showed reduced response to challenging the sympathetic innervation. In conclusion, we have identified an important new chemo-active Slit2-Robo1 pathway required for correct cardiac innervation development.

developmental biology↗

bioRxiv2025

microRNA-210 enhances cell survival and paracrine potential for cardiac cell therapy while targeting mitophagy.

The therapeutic potential of presumed cardiac progenitor cells (CPCs) in heart regeneration has garnered significant interest, yet clinical trials have revealed limited efficacy due to challenges in cell survival, retention, and expansion. Priming CPCs to survive the hostile hypoxic environment may be key to enhancing their regenerative capacity. We demonstrate that microRNA-210 (miR-210), known for its role in hypoxic adaptation, significantly improves CPC survival by inhibiting apoptosis through the downregulation of Casp8ap2, reduction of caspase activity, and decreased DNA fragmentation. Contrary to the expected induction of Bnip3-dependent mitophagy by hypoxia, miR-210 did not upregulate Bnip3, indicating a distinct anti-apoptotic mechanism. Instead, miR-210 reduced markers of mitophagy and increased mitochondrial biogenesis and oxidative metabolism, suggesting a role in metabolic reprogramming. Furthermore, miR-210 enhanced the secretion of paracrine growth factors from CPCs, which promoted in vitro endothelial cell proliferation and cardiomyocyte survival. These findings elucidate the multifaceted role of miR-210 in CPC biology and its potential to enhance cell-based therapies for myocardial repair by promoting cell survival, metabolic adaptation, and paracrine signalling.

developmental biology↗

bioRxiv2024

Transcriptomic analysis of adult mouse cardiac stromal cells using single-cell qRT-PCR

Fate mapping studies have challenged the longstanding view of the adult mammalian heart as a post-mitotic organ, suggesting limited cardiomyocyte renewal. This has spurred efforts to identify cardiac progenitor cell (CPC) populations, but their contribution to cardiac regeneration has been found to be minimal compared to cardiomyocyte proliferation. Despite this, CPC transplantation has shown therapeutic potential through paracrine signalling. The identity of CPCs remains unclear due to overlapping characteristics with other cardiac stromal cell populations such as fibroblasts, mesenchymal cells, and pericytes. This study sought to optimise the isolation of CPCs by developing a cardiac collagenase-trypsin (CT) protocol, which was compared to the established method of isolating cardiosphere-derived cells (CDCs). The CT protocol resulted in a higher cell yield and reduced expansion time, with both CTs and CDCs showing superior survival potential under serum starvation compared to commercially acquired cardiac fibroblasts (CFs). Single-cell qRT-PCR analysis revealed that CTs and CDCs share a similar gene expression profile, distinct from CFs, characterised by the enrichment of cardiogenic transcription factors. Notably, CTs exhibited higher expression of Tcf21 and lower Tbx5, suggesting an epicardial-derived fibroblast phenotype, whereas Tbx5 was enriched in CDCs and CFs. Additionally, CTs showed an enrichment of macrophage-associated genes Mrc1 and Csf1r, possibly due to the transdifferentiation of macrophages to or from a fibroblast phenotype in a subset of CTs. The study concludes that CTs represent a robust and efficient source of CPCs with therapeutic potential and offers insights into the complex identity of cardiac stromal cells.

developmental biology↗

bioRxiv2024

GTP hydrolysis triggers membrane remodeling by AMPH-1

Membrane-enclosed transport carriers return biological molecules from the recycling endosome to the plasma membrane using a mechanism that is not well understood. In C. elegans, the formation of carriers from the recycling endosome requires the amphiphysin protein, AMPH-1. Recently, we found that purified AMPH-1 is sufficient for tubulation and vesiculation of liposomes in a mechanism that is regulated by guanine nucleotides. Here we propose a model linking GTP binding and hydrolysis to the membrane binding and tubulation required for transport carrier formation. We find that GTP binding stabilizes interactions between AMPH-1 and the membrane through amphipathic, N-terminal alpha helices, which are found at the tips of the arc-shaped, homodimeric structure. By contrast, in the post-hydrolysis, GDP-bound state, these helices are repositioned to interact with the N-terminal helices of other homodimers, to form an oligomeric AMPH-1 lattice that tubulates the membrane, in preparation for carrier formation by membrane fission.

biochemistry↗