Biology subjects

Horvat, J.

Publications and source records attributed to Horvat, J..

3 recordsLinked to original sources

bioRxiv2025

Microbiota Modulation Induces Elevated Duodenal Eosinophils Upon Gluten Exposure in Mice: Implications for Non-Coeliac Gluten Sensitivity

A growing proportion of the non-celiac population experience adverse symptoms to gluten. The pathogenesis of non-coeliac gluten sensitivity (NCGS) is unclear, but elevated duodenal eosinophils and altered mucosa-associated microbiota (MAM) populations have been reported. Given the microbiomes role in gluten digestion and its susceptibility to antibiotics, we hypothesised that altering the microbiome with antibiotics would modify immune responses to gluten in mice. BALB/C mice consuming gluten-free chow received amoxicillin/clavulanate (5mg/kg) or PBS-vehicle daily for 5 days. Mice were then treated with a 3mg wheat-gluten suspension, or vehicle, on days 4 and 5 before sacrifice on day 7. Duodenal immune cells were analysed by histology and flow cytometry, while the duodenal MAM and faecal microbiome were characterised via 16S rRNA and shotgun metagenomic sequencing, respectively. Antibiotic treatment followed by gluten reintroduction significantly reduced Staphylococcus in the duodenal MAM, enriched Bacteroides in faeces, and resulted in altered microbial carbohydrate and lipid metabolism, compared to vehicle controls. Treatment with antibiotics and gluten also increased duodenal eosinophils which positively correlated with the genus Blautia. Flow cytometry revealed that antibiotics and gluten treatment resulted in a greater proportion of active eosinophils and epithelial {gamma}{delta} T-cells, compared to vehicle control mice. This study demonstrated that modulating the microbiome with antibiotics was sufficient to alter the immune response to gluten in mice. These findings suggest that the microbiome may determine the capacity for gluten to induce an immune response and offers a valuable insight into potential mechanisms underlying NCGS. New & NoteworthyA mouse model examined how microbial modulation affects immune responses to gluten. Antibiotic treatment followed by gluten reintroduction reduced duodenal Staphylococcus and altered microbial carbohydrate and lipid metabolism pathways in the faecal microbiome. Antibiotics and gluten treatment resulted in increased abundance and activation of duodenal eosinophils, and elevated {gamma}{delta} T-cells in the duodenal epithelium. These findings highlight the role the microbiome plays in gluten-induced immune responses, providing insights into mechanisms behind non-coeliac gluten sensitivity.

immunology↗

bioRxiv2024

The effects of iron deficient and high iron diets on SARS-CoV-2 lung infection and disease

The severity of Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is often dictated by a range of comorbidities. A considerable literature suggests iron deficiency and iron overload may contribute to increased infection, inflammation and disease severity, although direct causal relationships have been difficult to establish. Here we generate iron deficient and iron loaded C57BL/6J mice by feeding low and high iron diets, with mice on a normal iron diet representing controls. All mice were infected with a primary omicron XXB SARS-CoV-2 isolate and lung inflammatory responses were analyzed by histology, immunohistochemistry and RNA-Seq. Compared with controls, iron deficient mice showed no significant changes in lung viral loads or histopathology, whereas, iron loaded mice showed slightly, but significantly, reduced lung viral loads and histopathology. Transcriptional changes were modest, but illustrated widespread dysregulation of inflammation signatures for both iron deficient vs. controls, and iron loaded vs. controls. Some of these changes could be associated with detrimental outcomes, whereas others would be viewed as beneficial. Diet-associated iron deficiency or overload thus induced modest modulations of inflammatory signatures, but no significant histopathologically detectable disease exacerbations. Author summaryA diet deficient in iron can lead to anemia, a widespread problem worldwide. A diet with excessive iron is less common, but can be associated with excessive consumption of iron supplements. We investigate herein using a mouse model, whether low or high iron diets predispose to detrimental outcomes in the lungs after infection with SARS-CoV-2. A considerable literature suggests iron dysregulation would promote infection and inflammation. However, we found, although inflammatory responses showed modest modulations, viral loads were unaffected or slightly reduced, and lung histopathology was either unaffected or indicated slightly less severe disease. These findings do not support a view that low or high iron diets represent comorbidities predisposing to overt detrimental outcomes for acute COVID-19 lung disease.

pathology↗

bioRxiv2023

Impact of central carbon metabolism bypasses on the production of beta-carotene in Yarrowa lipolytica

Yarrowia lipolytica is an oleaginous yeast with ever growing popularity in the metabolic engineering circles. It is well known for its ability to accommodate a high carbon flux through acetyl-CoA and is being extensively studied for production of chemicals derived from it. We investigated the effects of modifying the upstream metabolism leading to acetyl-CoA on beta-carotene production, including its titer, yield, and content. We examined the pyruvate and the phosphoketolase bypass, both of which are stoichiometrically favorable for the production of acetyl-CoA and beta-carotene. Additionally, we examined a set of genes involved in the carnitine shuttle. We constructed a set of parental strains derived from the Y. lipolytica YB-392 wild-type strain, each with a different capacity for beta-carotene production, and introduced genes for the metabolic bypasses in each of the constructed parental strains. Subsequently, we subjected these constructed strains to a series of fermentation experiments. We discovered that altering the upstream metabolism in most cases led to a decrease in performance for production of beta-carotene. Most notably, a set of genes used for the pyruvate bypass (YlPDC2, YlALD5, and YlACS1) and the phosphoketolase bypass (LmXPK and CkPTA) resulted in the reduction of more than 30%. Our findings contribute to our understanding of Y. lipolyticas metabolic capacity and suggest that production of beta-carotene is most likely not limited solely by the acetyl-CoA supply. We also highlight a complex nature of engineering Y. lipolytica, as most of the results from studies using a different strain background did not align with our findings.

bioengineering↗