DEATH OF PERITONEAL MOUSE MACROPHAGES INFECTED WITH Clostridium chauvoei

CÁCERES, CLAUDIA SOLEDAD; COLOCHO, FLORENCIA AMANCAY; GARAY, JUAN AGUSTÍN; MATTAR, MARÍA AÍDA

Mendoza

Jornada; XXXVI Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2018

Sociedad de Biología de Cuyo

Clostridium chauvoei is an anaerobic bacillus which is the causative agent of blackleg, a clostridialmyonecrosis that has an important impact on the sheep and cattle industry worldwide. Blackleg is considered a gaseousgangrene which is an acute disease with a poor prognosis and often fatal outcome. Initial trauma in the host results in muscle damage and impaired blood supply. Early symptoms are generalized fever and pain in the infected tissue. One of the most outstanding characteristics of the myonecrosis produced by this microorganism is the absence of phagocytic cells at the site of infection. Both the induction of apoptosis and necrosis are considered mechanisms of evasion of the innate immune system caused by some microorganisms, since they achieve the destruction of key cells of the immune system. The objective of this work was to evaluate the ability of C. chauvoei to induce apoptosis and/or necrosis in mouse peritoneal macrophages at different multiplicities of infection (MOI): 1:1, 10:1 and 100:1 at different times (4, 10 and 24 h). C. chauvoei ATCC 10092 cells obtained in logarithmic phase of growth were assayed. The mouse phagocytic cells where grown in DMEM medium supplemented with 10% fetal calf serum and incubated in atmosphere enriched with 5% C02 at 37°C. The production of apoptosis and/or necrosis was determined by preliminary tests based on morphological changes observed by optical microscopy (Giemsa stain). All MOIshowed significant apoptotic index at all times assayed as compared to the control. Apoptosis was observed at low MOI and in the early stages of infection. In contrast, necrotic cell characteristics were observed at high MOI and 24 hincubation. On the other hand, in all the conditions tested, a phenomenon of autophagy characteristic of cells subjected to physical stress and infection was observed, triggering macrophage death by necrosis in the last incubation hours and at a high infectious dose. This work is the first approach to the determination of apoptosis and necrosis of mouse peritoneal macrophages at different infective doses and post-infection times with C.chauvoei cells. Our results support the study of cell death mechanisms to elucidate the pathogenic potential of this bacterium and the search of treatments aimed to avoid the large economic losses produced in cattle.