2nd International Workshop on Adverse Drug Reactions and Lipodystrophy in HIV 13-15 September 2000, Toronto, Canada

ULTRASTRUCTURAL FINDINGS CONSISTENT WITH BROWN ADIPOCYTES IN BUFFALO HUMPS OF HIV-POSITIVE PATIENTS WITH FAT REDISTRIBUTION SYNDROME

Antiviral Therapy 2000; 5(Suppl. 5):25 (abstract no. P1)

WJ Fessel, SB Follansbee and B Barker
Kaiser Permanente Medical Center, San Francisco, Calif., USA

BACKGROUND: Expanded central fat, seen in some HIV-infected patients treated with antiretroviral therapy, has the same anatomical distribution as brown fat. This preliminary report shows that some adipocytes in buffalo humps have ultrastructural characteristics of brown fat.

METHODS: Biopsies of fat taken from buffalo humps of four patients and from wasted arms of three of them, were examined by electron microscopy. Coded photomicrographs were analysed independently by two observers for the following characteristics of brown adipocytes: clarity (scale 1-3) of outer membranes of mitochondria and of cristae; full extension (scale 1-3) of cristae between mitochondrial outer membranes; and presence or absence in cytoplasm of multilocular fat globules. Mitochondrial vacuoles were noted as positive or negative. Interobserver agreement was 78%; discussion resolved differences. Before uncoding their source, predictions were made as to whether photomicrographs were of central or peripheral fat. High scores for clarity of membranes (outer mitochondrial and cristal), extension of cristae between mitochondrial outer membranes and multilocular fat globules, predicted buffalo humps' adipocytes.

RESULTS: Correctly predicted: adipocytes of buffalo humps, four of four; adipocytes of arms, one of three. Overall predictions, 71% correct, trended towards statistical significance (P=0.14). One specimen from a wasted arm showed a typical brown adipocyte. There were multiple vacuoles within many mitochondria in biopsies from two of the four buffalo humps and two of the three arms. Individual cristae, detached from the mitochondrial outer membranes and curled into circles, formed these vacuoles.

CONCLUSIONS: Mitochondrial damage occurs in both peripheral and central fat. Some adipocytes in buffalo humps have characteristics of brown adipocytes. These preliminary observations support the hypothesis that expanded central fat in the fat redistribution syndrome includes brown fat that has become used for storage after white fat has been more extensively damaged. This could imply that it might also occur peripherally, as we saw multilocular fat globules plus some mitochondrial characteristics of brown adipocytes in wasted fat.

000913
P1

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