Encephalitic
listeriosis in sheep is a life-threatening disease. However, little is known about the
cytokine response and their predictive value in this disease. The aim of present study was to assess the prognostic significance of
Tumor Necrosis Factor-α (TNF-α), Interleukin-12(p40) (IL-12 p40),
Interleukin-6 (IL-6), and
Interleukin 10 (IL-10) levels in cerebrospinal fluid (CSF) in sheep with encephalitic
listeriosis. Fifty-nine ewes in 14 flocks were diagnosed clinically as having
listeriosis. CSF was collected and subjected to bacteriological examination and estimation of selected
cytokines. Twenty-eight ewes were confirmed to be infected with Listeria monocytogenes. Based on antimicrobial sensitivity test, sheep were treated and the outcome was recorded as survivors (n=10) and non-survivors (n=18). Cutoff points for CSF
cytokines were determined by Receiver operating characteristic analysis (ROC). Association between levels of CSF
cytokines and outcome of
listeriosis was assessed by logistic regression. TNF-α,
IL-6 and IL-12(p40) levels as well as TNF-α/IL-10 ratio were significantly higher in non-survivors than survivors (p=0.002, 0.0021, 0.0033, and 0.001, respectively). However,
IL-10 level was significantly lower in non-survivors than survivors (p=0.0058). ROC analysis revealed that
IL-6 and TNF-α/IL-10 ratio had the highest AUC values (0.98, 0.984, respectively). Final multivariate logistic regression model showed that TNF-α/IL-10 ratio was the only variable that has predictive value for mortality in diseased sheep (p: 0.001; OR: 7.2; 95% CI: 5.7-9.8). TNF-α showed a positive correlation with IL-12β (r=0.917) and
IL-6 (r=0.965).
IL-12 (p40) showed also a positive correlation with
IL-6 (r=0.906). However,
IL-10 showed a negative correlation with TNF-α (r=-0.915), IL-12(p40) (r=-0.790), and
IL-6 (r=-0.902). In conclusion, TNF-α/IL-10 ratio may provide predictive information about outcome of encephalitic
listeriosis in sheep.