Isolation and characterization of endothelial cell growth factor from Bartonella henselae

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1. A liquid growth-medium for Bartonella henselae was developed and evaluated. The best growth was observed in brucella broth with hernin and FeSO_4 suggesting that iron has the important role in the growth of B. henselae.2. We tried to isolate the endothelial cell growth factor in the culture medium of B. henselae. The growth factor was estimated to be a protein with molecular weight of about 30,000. We obtained the high activity fraction eluted in the area of comparably high salt concentration by using a perfusion chromatography. However, the sufficient purification of this growth factor was not yet completed because of inactivation during the manipulation.3. B. henselae induced the production of IL-8 and MCP-1 in endothelial cells and monocytes. This effect was demonstrated not only by live bacteria but also by inactivated bacteria. Furthermore, the treatment of boiling or Polymyxin B did not inhibit this effect.4. The endothelial cell growth factor may be a heat-sensitive protein secreted from B. henselae, while the stimulatory factor of IL-8/MCP-1 may be a heat-resistant component of this organism. These factors may play the important role in the pathogenesis of B. henselae infection.5. B. henselae inhibited the apoptosis of peripheral neutrophils. This activity was also demonstrated by the culture medium of B. henselae. We obtained the single fraction that inhibited the neutrophil apoptosis by perfusion chromatography.6. In relation to the effect of B. henselae, Porphyromonas gingivalis was also shown to induce the production of IL-8/MCP-1 and the expression of ICAM-1 in endothelial cells. This activity was observed even by inactivated bacteria, and was not abolished by addition of polymyxin B or boiling.7. Pili did not participate in the stimulatory effects of B. henselae including induction of IL-8/MCP-1, proliferation of endothelial cells, and inhibition of neutrophil apoptosis.