Isolation and structural identification of 1,25-dihydroxyvitamin D3 produced by cultured alveolar macrophages in sarcoidosis.
Hypercalcemia and hypercalciuria in sarcoidosis are thought to result from the endogenous overproduction of an active vitamin D metabolite. We employed primary cultures of pulmonary alveolar macrophages from two patients with biopsy-proven pulmonary sarcoidosis and a recent or current clinical abnormality in calcium metabolism to synthesize in vitro a 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]-like metabolite from 25-hydroxyvitamin D3 (25OHD3). The macrophage metabolite cochromatographed with [3H]1,25-(OH)2D3 on normal phase and reverse phase high performance liquid chromatography and was bound with high affinity by the chick intestinal receptor for 1,25-(OH)2D3. On UV spectroscopy, the metabolite possessed the carbon-5,7,10 (19) cis-triene chromophore characteristic of a vitamin D sterol. Electron impact mass spectrometry of trimethylsilyl ether derivatives of the metabolite revealed a mass fragmentation pattern similar to that of the trimethylsilyl ether derivative of authentic 1,25-(OH)2D3. The incubation of cultured macrophages from two patients with idiopathic pulmonary fibrosis and two with scleroderma with [3H]25OHD3 did not result in production of a metabolite with the chromatographic identity of 1,25-(OH)2D3. These data indicate that the metabolite of 25OHD3 synthesized by sarcoid macrophages in vitro is 1,25-(OH)2D3 and that the macrophage is a synthetic source of the sterol metabolite in sarcoidosis.
Adams
J S
JS
Singer
F R
FR
Gacad
M A
MA
Sharma
O P
OP
Hayes
M J
MJ
Vouros
P
P
Holick
M F
MF
D000328:Adult; D002117:Calcitriol / Q000096:biosynthesis* / Q000302:isolation & purification; D002478:Cells, Cultured; D055598:Chemical Phenomena; D002621:Chemistry; D006801:Humans; D008171:Lung Diseases / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism*; D008297:Male; D013058:Mass Spectrometry; D011650:Pulmonary Alveoli / Q000378:metabolism*; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000378:metabolism; D012507:Sarcoidosis / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet
D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D002117:Calcitriol