Altered phospholipids in human rheumatoid synoviocytes.

Abstract

SUMMARY A specific cytochemical reaction for freely available phospholipids has shown a raised concentration of such phospholipids in the lining cells of human synovial membranes removed from rheumatoid joints. Quantitative measurement, by microdensitometry, of the amount of reactionproduct per cell showed that the rheumatoid synoviocytes contained almost three times the amount of free phospholipids present in the equivalent nonrheumatoid cells; statistically the difference was highly significant. Evidence from studies in which the bound phospholipids were 'unmasked' by methanol-chloroform confirmed the view that the increased content of freely available phospholipids was related to altered lipid-protein binding rather than to an increase in total phospholipids.

Metabolic alterations in human synovial lining cells in pigmented villonodular synovitis.

“…The activities of both glycolytic enzymes studied were of the levels found in rheumatoid synoviocytes, which Henderson et al (1978b) showed to be higher than in synovial lining cells from joints free from rheumatic disease. Similarly the -SH :-S-S ratio (almost 100% sulphydryl) and the availability ofcellular phospholipids (the acid haematein reaction) were very much as have been found in rheumatoid but not nonrheumatoid synovial lining cells Henderson et al, 1978a). Thus the metabolic behaviour of the synovial lining cells in these 3 specimens of villonodular synovitis was similar to, or exaggerated above, that found previously as typical of the synoviocytes of rheumatoid tissue.…”

“…By such procedures apparently characteristic alterations in the metabolism of rheumatoid synoviocytes have been recorded Henderson et al, 1978aHenderson et al, , b, 1979. During these studies on the metabolic activity of the synovial lining cells biopsies were obtained from 3 patients with unequivocal villonodular synovitis.…”

Mitochondrial oxidative activity in human rheumatoid synovial lining cells.

“…Thus these results imply that the increased availability of phospholipids in rheumatoid synoviocytes (Henderson et al, 1978) may assist the binding of cytochrome c and the stability of the cytochrome c-cytochrome oxidase complex, so enhancing the capability of rheumatoid mitochondria. They show that, despite some enhanced glycolysis, and considerable elevation of the hexose monophosphate pathway, there may be no great difference in the potential mitochondrial oxidative activity associated with the rheumatoid condition.…”

“…It is known that cytochrome c binds to cytochrome oxidase, the degree of binding being dependent on phospholipid concentration, so that binding is increased parallel to an increase in phospholipid concentration (Tzagoloff and Mac-Lennan, 1965). Recent studies have revealed an increase in the available (unbound or unmasked) phospholipids in human rheumatoid synoviocytes (Henderson et al, 1978). It is therefore possible that the increased activity of cytochrome oxidase (tested without added cytochrome c) in rheumatoid synoviocytes is due to the greater binding of cytochrome c to cytochrome oxidase as a result of the increased concentration of unbound phospholipids.…”