Abstract
BackgroundRecent studies demonstrated that Aquamin®, a calcium-, magnesium-rich, multi-mineral natural product, improves barrier structure and function in colonoids obtained from the tissue of healthy subjects. The goal of the present study was to determine if the colonic barrier could be improved in tissue from subjects with ulcerative colitis (UC).MethodsColonoid cultures were established with colon biopsies from 9 individuals with UC. The colonoids were then incubated for a 2-week period under control conditions (in culture medium with a final calcium concentration of 0.25 mM) or in the same medium supplemented with Aquamin® to provide 1.5 – 4.5 mM calcium. Effects on differentiation and barrier protein expression were determined using several approaches: phase-contrast and scanning electron microscopy, quantitative histology and immunohistology, mass spectrometry-based proteome assessment and transmission electron microscopy.ResultsAlthough there were no gross changes in colonoid appearance, there was an increase in lumen diameter and wall thickness on histology and greater expression of cytokeratin 20 (CK20) along with reduced expression of Ki67 by quantitative immunohistology observed with intervention. In parallel, upregulation of several differentiation-related proteins was seen in a proteomic screen with the intervention. Aquamin®-treated colonoids demonstrated a modest up-regulation of tight junctional proteins but stronger induction of adherens junction and desmosomal proteins. Increased desmosomes were seen at the ultrastructural level. Proteomic analysis demonstrated increased expression of several basement membrane proteins and hemidesmosomal components. Proteins expressed at the apical surface (mucins and trefoils) were also increased as were several additional proteins with anti-microbial activity or that modulate inflammation. Finally, several transporter proteins that affect electrolyte balance (and, thereby affect water resorption) were increased. At the same time, growth and cell cycle regulatory proteins (Ki67, nucleophosmin, and stathmin) were significantly down-regulated. Laminin interactions, matrix formation and extracellular matrix organization were the top three up-regulated pathways with the intervention.ConclusionA majority of individuals including patients with UC do not reach the recommended daily intake for calcium and other minerals. To the extent that such deficiencies might contribute to the weakening of the colonic barrier, the findings employing UC tissue-derived colonoids here suggest that adequate mineral intake might improve the colonic barrier.
Highlights
An intact colonic barrier is necessary for gastrointestinal health (Coskun, 2014; France and Turner, 2017)
We showed that increasing the extracellular calcium concentration from a basal level of 0.25 mM to as high as 3.0 mM in human colon organoid culture had a modest effect on expression of tight junction proteins, but dramatically up-regulated desmosomal proteins (Attili et al, 2019)
While calcium provided as a single agent was effective, a calcium, magnesium, and multiple trace element-rich natural product (Aquamin R ) was more effective than calcium alone (McClintock et al, 2020). These findings indicate that colonoid culture technology can provide a useful tool for elucidating factors that affect barrier structure and function in the colon
Summary
An intact colonic barrier is necessary for gastrointestinal health (Coskun, 2014; France and Turner, 2017). Colonic barrier dysfunction is a consistent feature of inflammatory bowel disease, seen in both Crohn’s disease and ulcerative colitis (UC) (Salim Sa and Söderholm, 2011; Antoni et al, 2014; Vivinus-Nebot et al, 2014; Lee et al, 2018). Histologic evidence of reduced colonic inflammation and lower polyp incidence was demonstrated in two long-term polypprevention studies by a multi-mineral dietary approach in mice (Aslam et al, 2010, 2012). Recent studies demonstrated that Aquamin R , a calcium-, magnesiumrich, multi-mineral natural product, improves barrier structure and function in colonoids obtained from the tissue of healthy subjects. The goal of the present study was to determine if the colonic barrier could be improved in tissue from subjects with ulcerative colitis (UC)
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