Biology subjects

Marchbank, K.

Publications and source records attributed to Marchbank, K..

3 recordsLinked to original sources

bioRxiv2026

Oxidative Stress Susceptibility, Complement Dysregulation, and Metabolic Reprogramming in CFH Y402H Patient-Derived Choriocapillaris Endothelial Cells

Age-related macular degeneration (AMD) is a leading cause of central vision loss. Immunofluorescence and gene expression studies in human donor eyes have shown that choriocapillaris endothelial cells (CECs) are lost before retinal pigment epithelium (RPE) degeneration, leaving extracellular matrix-filled empty lumens known as "ghost vessels." To investigate disease mechanisms, we generated CECs from patient-specific induced pluripotent stem cells (iPSCs) carrying the high-risk CFH Y402H variant and CRISPR-Cas9-corrected isogenic controls. The iPSC-derived CECs expressed canonical endothelial markers, formed fenestrations, maintained barrier function, and assembled capillary-like structures. Although baseline metabolism was preserved, Y402H CECs showed heightened sensitivity to hydroquinone-induced oxidative stress, with increased cytotoxicity and deposition of the complement membrane attack complex (C5b-9). RNA sequencing revealed oxidative stress-driven upregulation of lipid biosynthesis, mTORC signalling, endothelial-to-mesenchymal transition, and angiogenic pathways, alongside an imbalance in the complement pathway. These findings demonstrate that the CFH Y402H polymorphism increases CEC vulnerability to environmental stress, linking complement dysregulation and metabolic reprogramming to choriocapillaris dysfunction in AMD and highlighting CECs as a potential therapeutic target.

Cell Biology↗

bioRxiv2026

Hijacking of inflammasome responses by the complement system during Pseudomonas aeruginosa-Aspergillus fumigatus sur-infection

Patients with cystic fibrosis (pwCF) are highly susceptible to chronic pulmonary infections due to mutations in the CFTR gene. From early childhood, pwCF experience repeated lung infections and often develop chronic bacterial and/or fungal colonization. Among the most clinically relevant pathogens, Pseudomonas aeruginosa and Aspergillus fumigatus frequently co-infect and are associated with worse outcomes, including excessive IL-1{beta}-driven inflammation and accelerated lung function decline. Here we investigated the mechanisms underlying inflammasome overactivation during super-infection. We found that inflammasome hyperactivation occurred across macrophage populations, was independent of exogenous priming, and required live co-infection with both pathogens. P. aeruginosa and A. fumigatus cooperatively activated the NLRP3 inflammasome, and this response required both caspase-1 and caspase-8. Unexpectedly, gasdermin D was dispensable for IL-1{beta} release. Bacterial flagellin, type IV pili and the type III secretion system, as well as the fungal polysaccharide galactosaminogalactan (GAG), were each required for overactivation. Mechanistically, P. aeruginosa activated the MyD88-TLR pathway, enhancing macrophage responses and promoting ITGAM (CD11b) expression. Under fungal super-infection, macrophages secreted complement component C3, which may bound fungal surface and engaged the complement receptor C3R (CD11b/CD18). Downstream SYK and ERK signaling amplified inflammasome activation and IL-1{beta} release. Single-cell transcriptomic analysis of pwCF broncho-alveolar lavage and lung samples supported coordinated upregulation of complement and inflammasome pathways during bacterial-fungal infection. Together, these findings identify a complement-inflammasome signaling axis that drives pathological inflammation during bacterial-fungal co-infection in airways of pwCF and may represent a therapeutic target.

immunology↗

bioRxiv2018

Utilisation of staphylococcal immune evasion protein Sbi as a novel vaccine adjuvant

Co-ligation of the B cell antigen receptor with complement receptor 2 on B-cells via a C3d-opsonised antigen complex significantly lowers the threshold required for B cell activation. Consequently, fusions of antigens with C3d polymers have shown great potential in vaccine design. However, these linear arrays of C3d multimers do not mimic the natural opsonisation of antigens with C3d. Here we investigate the potential of using the unique complement activating characteristics of Staphylococcal immune-evasion protein Sbi to develop a pro-vaccine approach that spontaneously coats antigens with C3 degradation products in a natural way. We show that Sbi rapidly triggers the alternative complement pathway through recruitment of complement regulators, forming a tripartite complex that acts as a competitive antagonist of factor H, resulting in enhanced complement consumption. These functional results are corroborated by the structure of this complement activating Sbi-III-IV:C3d:FHR-1 complex. Finally, we demonstrate that Sbi, fused with Mycobacterium tuberculosis antigen Ag85b, causes efficient opsonisation with C3 fragments, thereby enhancing the immune response significantly beyond that of Ag85b alone, providing proof of concept for our pro-vaccine approach.

biochemistry↗