4,029 research outputs found
Emerging role of extracellular vesicles in veterinary practice: novel opportunities and potential challenges
Extracellular vesicles are nanoscale vesicles that transport signals between cells, mediating both physiological and pathological processes. EVs facilitate conserved intercellular communication. By transferring bioactive molecules between cells, EVs coordinate systemic responses, regulating homeostasis, immunity, and disease progression. Given their biological importance and involvement in pathogenesis, EVs show promise as biomarkers for veterinary diagnosis, and candidates for vaccine production, and treatment agents. Additionally, different treatment or engineering methods could be used to boost the capability of extracellular vesicles. Despite the emerging veterinary interest, EV research has been predominantly human-based. Critical knowledge gaps remain regarding isolation protocols, cargo loading mechanisms, in vivo biodistribution, and species-specific functions. Standardized methods for veterinary EV characterization and validation are lacking. Regulatory uncertainties impede veterinary clinical translation. Advances in fundamental EV biology and technology are needed to propel the veterinary field forward. This review introduces EVs from a veterinary perspective by introducing the latest studies, highlighting their potential while analyzing challenges to motivate expanded veterinary investigation and translation
Investigating the role of complement in the pathogenesis of pre-eclampsia in previously healthy pregnant women, and in high-risk groups.
Pre-eclampsia (PE) is a leading cause of obstetric morbidity and mortality. Certain groups of women, including those with chronic kidney disease (CKD) and those of sub-Saharan African (SSA) ethnicity, are at particularly high risk. There remains no definitive treatment other than expedited delivery of baby and placenta. Previous studies suggest a role for complement dysregulation in the pathogenesis of PE, but results are often conflicting, and it remains unclear whether changes in circulating complement concentrations reflect a general heightened inflammatory state in PE or are directly associated with placental complement-mediated injury.
This thesis tested the hypothesis that PE is associated with excessive complement activation within placental tissue, with concurrent complement activation within the maternal and fetal circulation, and that groups with a high prevalence of PE, and of PE with severe features (women with CKD and women of SSA ethnicity) would exhibit a greater degree of systemic complement activation. Three arms of research were conducted, and I report:
• In a cohort of previously healthy women, PE was associated with significant placental complement deposition, associated with concurrent changes in maternal and fetal circulating complement markers (reduced maternal properdin and C4, and elevated maternal and fetal Ba). Placental C4d deposition was strongly correlated with maternal properdin and C4, suggesting that those patients with the most excessive changes in circulating markers of complement activation also have the greatest extent of placental complement-mediated damage.
• There was no evidence of excessive complement activation in the maternal circulation in superimposed PE in a cohort of women with CKD. However, raised Ba levels were associated with adverse pregnancy outcomes in women with CKD.
• There was no evidence of excessive complement activation in PE in a Ghanaian cohort of women of SSA ethnicity when compared to healthy pregnant controls. However, pregnant women of SSA ethnicity did have significantly elevated levels of C5b-9, serum free light chains, and immunoglobulin G, when compared to the UK-recruited cohorts; suggestive of a baseline elevated inflammatory state.
The results suggest that inhibition of complement activation is a potential therapeutic target for certain groups of women with PE. However, PE is a heterogenous syndrome and additional pathophysiological mechanisms may contribute to the development of disease in women with CKD and women of SSA ethnicity
LIPIcs, Volume 251, ITCS 2023, Complete Volume
LIPIcs, Volume 251, ITCS 2023, Complete Volum
T Follicular Helper cell dynamics in response to vaccination
High quality long lived humoral immune responses require significant help from T follicular helper (Tfh) cells located within the germinal centres (GC) of lymph nodes (LN). Cognate interactions established between Tfh cells and GC B cells regulates somatic hypermutation and affinity maturation, determining the quality of antibodies produced. However, the anatomically protected location of Tfh cells, within the LN, poses a significant logistical and ethical obstacle to in vivo interrogation in humans. This study utilised the fine needle biopsy (FNB) technique to directly probe the GCs of human axillary LNs pre- and post- seasonal influenza vaccination, with the aim to interrogate the commitment of CD4+ T cells to the Tfh cell lineage.
In this study, peripheral blood and draining and contralateral LN FNBs were collected prior to and 5 days post vaccination. Ex vivo phenotyping of LN FNB samples revealed significant expansion of GC Tfh cells was restricted to draining LNs. This early expansion of GC Tfh cells was characterised by an increase in highly activated, motile, and proliferating cells, measured by CD38, ICOS and Ki67 expression. Further, although no significant increase in the absolute number of Pre Tfh cells was observed, there was an increase in CD38+ICOS+ Pre-Tfh cells post vaccination, implicating this population in the immune response and highlighting the changes in cellular profile.
Characterisation of cellular subsets by traditional flow cytometry techniques is limited by the number of parameters available on the instrument. Therefore, we leveraged Smart-Seq2 single cell RNA-sequencing (scRNA-seq) to further examine the heterogeneity within GC Tfh and Pre-Tfh cells. In 3 participants, we identified 7 functionally distinct clusters of cells based on differentially expressed (DE) genes. A proliferating cluster and a motile cluster were observed in all participants. The proliferating cluster exhibited an activated, proinflammatory gene signature and was enriched for Tfh differentiation gene pathways, whereas the motile cluster was enriched for pathways involved in cellular migration and motility, critical for rapid reorganisation of GCs to support dynamic interactions and cellular reactivation.
To explore functional flexibility and plasticity of LN GC Tfh and Pre-Tfh, we integrated scRNAseq post vaccination data from 5 participants. Based on DE genes, we identified 5 distinct clusters; Resting, Activated migrating, B cell interacting Tfh, Proliferating and Cytotoxic. Trajectory analysis using inferred pseudotime revealed the transition of cells through activation states and the gain/loss of different CD4+ T cell lineage attributes and effector functions. Using the T cell receptor as a natural cellular barcode, we were able to identify divergent differentiation into different fate lineages from a common precursor cell.
Overall, the work presented in this thesis is the first to quantify the selective activation of GC Tfh and Pre-Tfh and provides exciting and promising initial evidence of the functional heterogeneity and plastic potential with the Tfh lineage in vivo in human axillary LNs in response to vaccination, that could be leveraged to develop more effective vaccines
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