Experimental infection of cattle with Listeria monocytogenes: Participation of purinergic metabolism in disease pathogenesis.

The objective of this study was to evaluate whether experimental infection with Listeria monocytogenes alters the activity of triphosphate diphosphohydrolase (NTPDase), 5'-nucleotidase, and adenosine deaminase (ADA) in cattle. Ten male Holstein breed cattle were divided in two groups of five animals each: a control group, and a group infected with a pathogenic strain of L. monocytogenes. We drew blood for platelets on days 0, 7 and 14 of the experiment. On the 14th day post infection (PI), the animals were euthanized. Brain, spleen and liver were processed for histopathological examination and measurement of enzyme activities. The five (n = 5/5) bovines experimentally infected by L. monocytogene were positive-PCR in hepatic tissue. In the brain, only four (n = 4/5) of these animals were positive-PCR for listeriosis. There were no differences in platelet counts between groups (P > 0.05). In platelets, NTPDase activity (with ATP and ADP as substrates) were higher on the 7th PI day in the infected group, whereas the activities of 5'-nucleotidase and ADA were higher on the 7th and 14th PI. In serum and liver, ADA activity was higher in infected animals, but was lower on day 14 PI in spleen. NTPDase activity (with ATP as substrate) was higher in the cerebellum of infected animals, but was lower in the cerebral cortex and medulla oblongata. NTPDase activity (with ADP as substrate) was lower in the cerebellum and cerebral cortex of infected animals, whereas 5'-nucleotidase was higher. ADA activity was lower in the cerebellum, cerebral cortex and medulla oblongata in infected animals compared with controls. In conclusion, there appears to be a protective immunomodulatory response in spleen and brain structures of cattle infected with L. monocytogenes.

Changes on the activity of cholinesterase's in an immunomodulatory response of cattle infected by Listeria monocytogenes.

The aim of this study was to evaluate whether Listeria monocytogenes infection alters the activity of cholinesterases in cattle to module their inflammatory response and neurotransmission. Thus, ten male bovines (Holstein) were divided into two groups of five animals each: uninfected (control) and L. monocytogenes infected. Blood samples were collected on days 0, 7 and 14 post-infection (PI) to evaluate the activity of acetylcholinesterase (AChE) in the blood, and seric butyrylcholinesterase (BChE) activity, as well as total protein, albumin, globulin and C-reactive protein (CPR) levels in serum. The AChE activity and acetylcholine (ACh) levels were measured in the central nervous system on day 14 PI, and histopathological analyses were also performed. The infected animals did not show apparent clinical signs of listeriosis, however histopathological alterations were seen in the intestines and spleens. On days 7 and 14 PI, AChE activity in the blood was lower in infected animals, as well the seric BChE activity on day 7 PI. In the cerebral cortex and cerebellum, AChE activity was lower in infected animals compared to the control group, while the ACh levels were higher in the cerebral cortex compared to uninfected animals. Moreover, seric levels of total protein, globulin and CRP were higher in infected animals on days 7 and 14 PI compared to the control group. Therefore, we concluded that acute infection by L. monocytogenes alters the cholinergic system through the reduction of cholinesterase enzymes in the blood, serum and cerebral tissues as an adaptive response to an anti-inflammatory effect in order to increase the ACh levels, an anti-inflammatory molecule with an important role in the host immunomodulation.