Vitamin D status and bone mineral density in African American children with Crohn disease.

BACKGROUND: Vitamin D deficiency and low bone mineral density (BMD) are complications of inflammatory bowel disease. Vitamin D deficiency is more prevalent among African Americans compared with whites. There are little data comparing differences in serum 25-hydroxyvitamin D (25OHD) concentrations and BMD between African American and white children with Crohn disease (CD). METHODS: We compared serum 25OHD concentrations of African American children with CD (n = 52) to white children with CD (n = 64) and healthy African American controls (n = 40). We also analyzed BMD using dual-energy x-ray absorptiometry results from our pediatric CD population. RESULTS: African American children with CD had lower serum 25OHD concentrations (16.1 [95% confidence interval, CI 14.5-17.9] ng/mL) than whites with CD (22.3 [95% CI 20.2-24.6] ng/mL; P < 0.001). African Americans with CD and controls exhibited similar serum 25OHD concentration (16.1 [95% CI 14.5-17.9] vs 16.3 [95% CI 14.4-18.4] ng/mL; NS). African Americans with CD exhibited no difference in serum 25OHD concentration when controlling for seasonality, disease severity, and surgical history, although serum 25OHD concentration was significantly decreased in overweight children (body mass index ≥85%, P = 0.003). Multiple regression analysis demonstrated that obese African American girls with CD had the lowest serum 25OHD concentrations (9.6 [95% CI 6.8-13.5] ng/mL). BMD was comparable between African American and white children with CD (z score -0.4 ± 0.9 vs -0.7 ± 1.2; NS). CONCLUSIONS: African American children with CD are more likely to have vitamin D deficiency compared with white children with CD, but have similar BMD. CD disease severity and history of surgery do not affect serum 25OHD concentrations among African American children with CD. African American children have low serum 25OHD concentrations, independent of CD, compared with white children. Future research should focus on how race affects vitamin D status and BMD in children with CD.

Isolation and characterization of dendritic cells and macrophages from the mouse intestine.

Within the intestine reside unique populations of innate and adaptive immune cells that are involved in promoting tolerance towards commensal flora and food antigens while concomitantly remaining poised to mount inflammatory responses toward invasive pathogens. Antigen presenting cells, particularly DCs and macrophages, play critical roles in maintaining intestinal immune homeostasis via their ability to sense and appropriately respond to the microbiota. Efficient isolation of intestinal DCs and macrophages is a critical step in characterizing the phenotype and function of these cells. While many effective methods of isolating intestinal immune cells, including DCs and macrophages, have been described, many rely upon long digestions times that may negatively influence cell surface antigen expression, cell viability, and/or cell yield. Here, we detail a methodology for the rapid isolation of large numbers of viable, intestinal DCs and macrophages. Phenotypic characterization of intestinal DCs and macrophages is carried out by directly staining isolated intestinal cells with specific fluorescence-labeled monoclonal antibodies for multi-color flow cytometric analysis. Furthermore, highly pure DC and macrophage populations are isolated for functional studies utilizing CD11c and CD11b magnetic-activated cell sorting beads followed by cell sorting.