Biology subjects

Parnell, G. P.

Publications and source records attributed to Parnell, G. P..

4 recordsLinked to original sources

bioRxiv2020

Identification of HIV-Transmitting Sub-Epithelial Mononuclear Phagocytes in Human Anogenital and Colorectal Tissues

Tissue mononuclear phagocytes (MNP) are specialised in pathogen detection and antigen presentation. They are the first cells of the immune system to encounter HIV and play a key role in transmission as they deliver the virus to CD4 T cells, which are the primary HIV target cell in which the virus undergoes replication. Most studies have investigated the role that epithelial MNPs play in HIV transmission but, as mucosal trauma and inflammation are strongly associated with HIV transmission, it is also important to examine the role that sub-epithelial MNPs play. Sub-epithelial MNPs are present in a diverse array of subsets which differ in their function and the pathogens they detect. Understanding how specific subsets interact with HIV and deliver the virus to CD4 T cells is therefore of key importance to vaccine and microbicide development. In this study we have shown that, after topical application, HIV can penetrate to interact with sub-epithelial resident myeloid cells in anogenital explants and defined the full array of MNP subsets that are present in all the human anogenital and colorectal sub-epithelial tissues that HIV may encounter during sexual transmission. In doing so we have identified two subsets that preferentially take up HIV, become infected and transmit the virus to CD4 T cells; CD14+CD1c+CD11c+ monocyte-derived dendritic cells and langerin-expressing dendritic cells 2 (DC2).

immunology↗

bioRxiv2020

Age-dependent VDR peak DNA methylation as a mechanism for latitude-dependent MS risk

BackgroundThe mechanisms linking UV radiation and vitamin D exposure to the risk of acquiring the latitude and critical period dependent autoimmune disease, multiple sclerosis, is unclear. We examined the effect of vitamin D on DNA methylation as well as DNA methylation at vitamin D receptor binding sites in adult and paediatric myeloid cells. ResultsVery few DNA methylation changes occurred in adult and paediatric cells treated with calcitriol. However, several VDR binding sites across the genome demonstrated increased DNA methylation in cells of adult origin. Genes associated with these VDR binding sites were enriched for intracellular signalling and cell activation pathways, suggesting that age-dependent potential for myeloid cell differentiation and adaptive immune system regulation may be encoded for by DNA methylation. ConclusionsThese results suggest vitamin D exposure at critical periods in immune system development may contribute to the well characterised latitude related differences in autoimmune disease incidence.

genetics↗

bioRxiv2018

Genetic evidence that the latency III stage of Epstein-Barr Virus infection is a therapeutic target for Multiple Sclerosis

Genome wide association studies have identified >200 susceptibility loci accounting for much of the heritability of Multiple Sclerosis (MS). Epstein Barr virus (EBV), a memory B cell tropic virus, has been identified as necessary but not sufficient for development of MS, with evidence for disease causation. The molecular and immunological basis for this has not been established. LCL proliferation is driven by signalling through the EBV produced cell surface protein LMP1, a homologue of the MS risk gene CD40. We show that the CD40 ligand, CD40L, potentially through competitive signalling with LMP1, reduces LCL proliferation (p<0.001). The MS risk variants of the LMP1 signalling inhibitor, TRAF3, had altered expression in B cells and LCLs. Both CD40 and TRAF3 risk SNPs are in binding sites for the EBV transcription factor EBNA2. We have investigated transcriptomes of B cells and EBV infected B cells at Latency III (LCLs) and identified 47 MS risk genes with altered expression, associated with the risk genotype. Overall these MS risk SNPs were overrepresented in target loci of the EBV transcription factor EBNA2 (p<10-16), in genes dysregulated between B and LCLs (p<10-5), and as targets for EBV miRNAs (p<10-4). The risk gene ZC3HAV1 is the putative target for multiple EBV miRNAs. It amplifies the interferon response, and was shown to have reduced expression in LCLs for the risk allele. These data indicate targeting EBV EBNA2, miRNAs, and MS risk genes on the LMP1/LMP2 pathways, and the pathways themselves, may be of therapeutic benefit in MS.

genomics↗

bioRxiv2016

Mortality prediction in sepsis via gene expression analysis: a community approach

Improved risk stratification and prognosis in sepsis is a critical unmet need. Clinical severity scores and available assays such as blood lactate reflect global illness severity with suboptimal performance, and do not specifically reveal the underlying dysregulation of sepsis. Here three scientific groups were invited to independently generate prognostic models for 30-day mortality using 12 discovery cohorts (N=650) containing transcriptomic data collected from primarily community-onset sepsis patients. Predictive performance was validated in 5 cohorts of community-onset sepsis patients (N=189) in which the models showed summary AUROCs ranging from 0.765-0.89. Similar performance was observed in 4 cohorts of hospital-acquired sepsis (N=282). Combining the new gene-expression-based prognostic models with prior clinical severity scores led to significant improvement in prediction of 30-day mortality (p<0.01). These models provide an opportunity to develop molecular bedside tests that may improve risk stratification and mortality prediction in patients with sepsis, improving both resource allocation and prognostic enrichment in clinical trials.

bioinformatics↗