RESUMO
Susceptibility to invasive amebiasis has been suggested to be due to intrinsic amebic factors and/or to such host factors as intestinal microflora, mucus and colonic redox potential. We investigated the effect of rat colon components on the growth of axenically cultured E. histolytica trophozoites. Extracts of rat colon tissue produced a 57% amebic growth inhibition. The main growth inhibitory components were precipitated by 65% ammonium sulfate and were heat-sensitive. These components were partially separated by ultrafiltration and gel filtration chromatography. Thus, we found colonic components (Mr 50-100 kDa) that produced strong growth inhibition (75%). These results suggest that rat colonic products may play an active role in resistance to amebic infection.
Assuntos
Colo/química , Entamoeba histolytica/efeitos dos fármacos , Inibidores do Crescimento/farmacologia , Animais , Cromatografia em Gel , Entamoeba histolytica/crescimento & desenvolvimento , Inibidores do Crescimento/isolamento & purificação , Masculino , Ratos , Ratos Wistar , Extratos de Tecidos/farmacologia , UltrafiltraçãoRESUMO
It is generally accepted that hydrolytic and cytolytic amebic components are involved in the pathogenic mechanisms of E. histolytica. We have now identified a lytic activity in two membrane proteins of 23.5 kDa and 25 kDa, which are able to lyse rat erythrocytes. The activity was purified from total homogenates of the virulent strains HM1:IMSS and HM38:IMSS, and the erythrocyte lysis was directly related to protein concentration. The hemolytic activity was heat-sensitive and resistant to reduction by 2-mercaptoethanol. Total amino acid analysis of pure proteins showed a high hydrophobic amino acid content: 36% for 23.5 kDa and 50% for 25 kDa. This hemolytic activity could be related, along with other amebic factors, to tissue damage.