Browsing by Author "Ferraz, Jose"

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    Assessment of Blood-Derived Macrophages from Individuals with Crohn's Disease: Potential Role of Diet and Selenium
    (2024-01-04) Sousa, James Amedeo; Raman, Maitreyi; McKay, Derek; Ferraz, Jose; Canton, Johnathan
    There is growing evidence of the role of diet in modulating immune function in inflammatory conditions such as inflammatory bowel disease (IBD). Specifically, there are alterations in macrophage populations and function found in patients with IBD such as reduced polarization to the M(IL-4) phenotype. Moreover, there are specific micronutrients such as selenium (Se) that patients with IBD are commonly deficient in and can also affect macrophage function and polarization. However, whether dietary intervention or Se intake can impact macrophage polarization and function in patients with Crohn’s disease (CD) is unknown. Therefore, utilizing a selenium rich Mediterranean therapeutic diet intervention (TDI) in patients with active CD, I addressed the following hypotheses: 1) there are innate differences in macrophages derived from healthy donor and patients with CD that can be modified by diet intervention and 2) that macrophages derived from patients with active CD are more prone to H2O2-induced cytotoxicity through the ferroptosis pathway. This is the first study that I am aware of to show reduced selenoprotein expression in monocyte-derived macrophages from patients with CD. This suggests reduced antioxidant defence and is further supported by increased H2O2-induced cytotoxicity compared with healthy macrophages. The TDI was beneficial with improvement in biomarkers of disease activity and dietary habits. However, there was no significant effect on the Se status of the patients. There was, however, a relationship between the M(IL-4) CD206 mRNA response and change in CRP concentration after diet intervention. Despite being able to increase GPx1 expression, Se supplementation in vitro had no significant effect on macrophage polarization to the M(IL-4) phenotype. Lastly, markers of ferroptosis were increased in healthy and patient-derived macrophages treated with H2O2, indicating that H2O2-induced cell death through the ferroptosis pathway. The differences found in selenoprotein expression and reduced antioxidant defence between healthy volunteer and patient-derived macrophages highlights the role of oxidative stress in IBD. In terms of the TDI, there is evidence of its therapeutic effect and positive impact on macrophages. Lastly, the increased cytotoxicity in CD derived-macrophages further evokes the need to study the physiological impacts of macrophage ferroptosis in IBD pathophysiology.
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    Pathobiont release from dysbiotic gut microbiota biofilms in intestinal inflammatory diseases: a role for iron?
    (2019-01-03) Buret, Andre G; Motta, Jean-Paul; Allain, Thibault; Ferraz, Jose; Wallace, John L
    Abstract Gut microbiota interacting with an intact mucosal surface are key to the maintenance of homeostasis and health. This review discusses the current state of knowledge of the biofilm mode of growth of these microbiota communities, and how in turn their disruptions may cause disease. Beyond alterations of relative microbial abundance and diversity, the aim of the review is to focus on the disruptions of the microbiota biofilm structure and function, the dispersion of commensal bacteria, and the mechanisms whereby these dispersed commensals may become pathobionts. Recent findings have linked iron acquisition to the expression of virulence factors in gut commensals that have become pathobionts. Causal studies are emerging, and mechanisms common to enteropathogen-induced disruptions, as well as those reported for Inflammatory Bowel Disease and colo-rectal cancer are used as examples to illustrate the great translational potential of such research. These new observations shed new light on our attempts to develop new therapies that are able to protect and restore gut microbiota homeostasis in the many disease conditions that have been linked to microbiota dysbiosis.