Biology subjects

Cruickshank, S. M.

Publications and source records attributed to Cruickshank, S. M..

4 recordsLinked to original sources

bioRxiv2025

Keratinocyte Arginase1 Deficiency Impairs Healing and Antimicrobial Defence against Pseudomonas aeruginosa Infection

Wound infection is a major disruptor of wound healing. Keratinocytes, critical in repair and microbial responses, require the L-arginine hydrolysing enzyme arginase1, for effective healing. Wound pathogens such as Pseudomonas aeruginosa may also need L-arginine. We therefore investigated host-microbial interactions in the context of wound healing and L-arginine metabolism. Arginase-inhibited murine wounds challenged with P. aeruginosa, exhibited significantly delayed re-epithelialisation. This finding was recapitulated in vitro using P. aeruginosa-challenged, arginase1 deficient (shARG1) keratinocytes, associated with reduced epithelial proliferation and viability, and heightened inflammation. Whilst P. aeruginosa challenge promoted host metabolism of L-arginine, this was perturbed in wounded shARG1 keratinocytes. There was, however, heightened downstream polyamine metabolism in shARG1 cells when under P. aeruginosa challenge. Host keratinocyte arginase1 deficiency promoted bacterial growth in vitro, in line with a failure to upregulate the anti-microbial peptides, {beta}-defensins, in shARG1 scratches. This work demonstrates a pivotal role for keratinocyte arginase1 in wound infection. HIGHLIGHTSO_LIHost arginase is required for effective healing under P. aeruginosa challenge. C_LIO_LIP. aeruginosa enhances host keratinocyte L-arginine metabolism upon scratch. C_LIO_LIP. aeruginosa promotes polyamine metabolism in arginase1 deficient wounds in vitro. C_LIO_LIArginase1 is required for keratinocyte anti-microbial defence against P. aeruginosa. C_LI

microbiology↗

bioRxiv2021

Morphological variability in the mucosal attachment site of Trichuris muris revealed by X-ray microcomputed tomography

Parasitic infections can be challenging to study, because light and electron microscopy are often limited in visualising complex and inaccessible attachment sites. Exemplifying this, Trichuris spp. inhabits a tunnel of epithelial cells within the host caecum and colon. A significant global burden of this infection persists partly because available anthelminthics lack efficacy, although the mechanisms underlying this remain unknown. Consequently, there is a need to pioneer new approaches to better characterize the parasite niche within the host and investigate how variation in its morphology and integrity may contribute to resistance to therapeutic intervention. To address these aims, we exploited 3D X-ray micro-computed tomography (microCT) to image the mouse whipworm T. muris in caeca of wild-type C57BL/6 and SCID mice ex vivo. Using osmium tetroxide staining to effectively enhance contrast of worms, we found that a subset exhibited preferential positioning towards the bases of the intestinal crypts. Moreover, in one rare event, we demonstrate whipworm traversal of the lamina propria. This morphological variability contradicts widely accepted conclusions from conventional microscopy of the parasite niche, showing Trichuris in close contact with the host proliferative and immune compartments that may facilitate immunomodulation. Furthermore, by using a skeletonization-based approach we demonstrate considerable variation in tunnel length and integrity which may represent an indicator of tunnel "health". The qualitative and quantitative observations provide a new morphological point of reference for future in vitro study of Trichuris-host interactions and highlight the potential of microCT to more accurately characterise enigmatic host-parasite interactions. Author SummaryParasites are often difficult to observe once established within host tissues, presenting a barrier to biological understanding and therapeutic innovation. Whipworms (Trichuris spp.) affect 500 million people worldwide, causing significant disability, and appear partially resistant to widely used "deworming" drugs. However, the inaccessibility of worms within the cells of the host intestine makes them highly challenging to image and study. By investigating Trichuris attachment sites in 3D, using X-ray micro-computed tomography, we found that the niche is highly variable in size and, contrary to reports in all previous studies, can also penetrate different layers of intestinal tissue. By showing that worms are positioned much closer to host immune cells that previously appreciated, we provide a morphological reference point for future studies on how Trichuris effectively avoids clearance by the host. The non-invasive imaging approach used represents an excellent opportunity to clarify the lifecycles of other difficult-to-study parasites.

microbiology↗

bioRxiv2019

Distinct microbial communities in the murine gut are revealed by taxonomy-independent phylogenetic random forests

Gut microbiome analysis using 16S rRNA frequently focuses on summary statistics (e.g. diversity) or single taxonomic scales (e.g. Operational Taxonomic units, OTUs). This approach risks misinterpreting the phylogenetic or abundance scales of community differences (e.g. over-emphasising the role of single strains). We therefore constructed a 16S phylogenetic tree from mouse stool and colonic mucus communities. Random forest models, of all 428,234 clades, tested community differences among niches (stool versus mucus), host ages (6 versus 18 weeks), genotypes (wildtype versus colitis prone-mdr1a-/-) and social groups (co-housed siblings). Models discriminated all criteria except host genotype, where no community differences were found. Host social groups differed in abundant, low-level, taxa whereas intermediate phylogenetic and abundance scales distinguished ages and niches. Thus, treating evolutionary clades of microbes equivalently without reference to OTUs or taxonomy, clearly identifies whether and how gut microbial communities are distinct and provides a novel way to define functionally important bacteria.

microbiology↗

bioRxiv2019

Differential expression of soluble receptor for advanced glycation end-products (sRAGE) in mice susceptible or resistant to chronic colitis

AimsIdentifying the factors that contribute to chronicity in inflamed colitic tissue is not trivial. However, in mouse models of colitis, we can investigate at preclinical timepoints. We sought to validate murine Trichuris muris infection as a model for identification of factors that promote development of chronic colitis.\n\nMethodsWe compared preclinical changes in mice with a resolving immune response to T. muris (resistant) versus mice that fail to expel the worms and develop chronic colitis (susceptible). Findings were then validated in healthy controls and patients with suspected or confirmed IBD.\n\nResultsThe Receptor for Advanced Glycation End Products (Rage) was highly dysregulated between resistant and susceptible mice prior to the onset of any pathological signs. Increased soluble RAGE (sRAGE) in the serum and faeces of resistant mice correlated with reduced colitis scores. Mouse model findings were validated in a preliminary clinical study: faecal sRAGE was differentially expressed in patients with active IBD compared with IBD in remission, patients with IBD excluded or healthy controls.\n\nConclusionPre-clinical changes in mouse models can identify early pathways in the development of chronic inflammation that human studies cannot. We identified the decoy receptor sRAGE as a potential mechanism for protection against chronic inflammation in colitis in mice and humans. We propose that the RAGE pathway is clinically relevant in the onset of chronic colitis, and that further study of sRAGE in IBD may provide a novel diagnostic and therapeutic target.

immunology↗