Objectives: The aim of the study was to examine the frequency of rickets and bone fractures and to assess areal bone mineral density (aBMD) in childhood among patients with biliary atresia (BA). Methods: We gathered data on all patients diagnosed with BA in Finland that survived to >= 1 year of age between 1 January 2000 to 30 June 2018. Data on gestational age, birth weight, postsurgical medications, and history of rickets and bone fractures were collected retrospectively. Serum levels of 25-hydroxyvitamin D [25(OH)D] postportoenterostomy (PE) were collected. Plain radiographs and dual energy X-ray absorptiometry (DXA) measurements of study subjects were reviewed. Results: Out of 49 patients, 7 (14%) were diagnosed with rickets during infancy. Clearance of jaundice [odds ratio 0.055, 95% confidence interval [CI] 0.00266-0.393; P < 0.01] was a protective factor against rickets. Sufficient 25(OH)D levels were reached 3 months post-PE. Eleven (22%) patients suffered at least one bone fracture (range 1-9) during childhood and adolescence. In DXA measurements, median lumbar spine aBMD anthropometrically adjusted z-scores were as follows: in native liver survivors 0.8 (interquartile range [IQR] -1.9 to 1.4) at 5 and -0.3 (IQR -1.3 to 0.8) at 10 years and for liver transplanted patients 0.4 (IQR -0.2 to 1.1) at 5 and 0.6 (IQR -0.1 to 1.3) at 10 years. Conclusions: BA patients have an increased risk for rickets and bone fractures compared with the normal population. Most BA patients have aBMD within normal range between 5 and 10 years of age irrespective of liver transplantation status.

Vitamin D is a fat-soluble vitamin that is metabolized by the liver into 25-hydroxyvitamin D [25(OH)D] and then by the kidney into 1,25-dihydroxyvitamin D [1,25(OH)(2)D], which activates the vitamin D receptor expressed in various cells, including immune cells, for an overall immunostimulatory effect. Here, to investigate whether oral supplementation of 25-hydroxyvitamin D-3[25(OH)D-3], a major form of vitamin D metabolite 25(OH)D, has a prophylactic effect on influenza A virus infection, mice were fed a diet containing a high dose of 25(OH)D(3)and were challenged with the influenza virus. In the lungs of 25(OH)D-3-fed mice, the viral titers were significantly lower than in the lungs of standardly fed mice. Additionally, the proinflammatory cytokines IL-5 and IFN-gamma were significantly downregulated after viral infection in 25(OH)D-3-fed mice, while anti-inflammatory cytokines were not significantly upregulated. These results indicate that 25(OH)D(3)suppresses the production of inflammatory cytokines and reduces virus replication and clinical manifestations of influenza virus infection in a mouse model.