Rate of apoptosis in human macrophages infected with Leishmania tropica promastigotes

Abstract

Infection of the cells with parasites or exposing cells to heatstress induces a cellular stress. In the present study humanmacrophages are infected withLeishmania tropicapromastigotesand exposed to heat stress. The measurement of cytoplasmic his-tone-associated DNA-fragments was carried out using ELISAtechnique. Visualization of apoptotic cells was performed by theterminal deoxynucleotidyl transferase dUTP nick end labelingstaining method (TUNEL). Degree of oxidative stress on cell isevaluated by measuring nitric oxide (NO), malondialdehyde(MDA), reducte glutathion (GSH) levels and superoxide dismu-tase (SOD) activities. Results of the ELISA technique showedthat infection of macrophages with promastigotes induced apop-tosis rate significantly (p<0.001), heat stress however decreasedthe rate of apoptosis in infected macrophages remarkably(p<0.001). High levels of apoptosis rate in infected macrophagesand drastic decdrease in apoptosis in heat subjected macrophagesinfected with promastigotes are confirmed by visualisation ofapoptotic cells using TUNEL method. Levels of glutathion(GSH) in infected macrophages decreased significantly (p<0.05),while malondialdehyde (MDA) levels increased notably(p<0.05). However, no statistical significant alterations weredetected in the nitric oxide (NO) values and superoxide dismutase(SOD) activities.Results of the present study indicates that infection of humanmacrophages withLeishmania tropicainduces a cellular stressresponse, characterized by decreased values of GSH andincreased levels of MDA. Increased rate of apoptosis in infectedmacrophages may be due to the increased cellular stress causedbyLeishmania tropicaamastigotes. Decreased rate of apoptosismeasured in heat exposed macrophages infected with promastig-otes indicates an extention in life span of macrophages. Furthermore extention in life span of macrophages may enableparasites to implement their differentiation process within thesecells.