Characterization of total adenosine deaminase activity (ADA) and its isoenzymes in saliva and serum in health and inflammatory conditions to four different species: an analytical and clinical validation pilot study

Abstract

Background: Measurement of adenosine deaminase (ADA) can provide information about cell-mediated immunity. This report’s objetive was to study the enzymatic activity of total ADA (tADA) and its isoenzymes ADA1 and ADA2 in canine, equine, porcine, and bovine serum and saliva and their changes in different inflammatory situations in each species. Besides, an automated method for ADA2 measurement was developed and validated.Results: tADA was present in serum and saliva of healthy animals of the four species. Erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) concentration of 0.47mM was needed for ADA1 inhibition in canine and porcine samples (serum and saliva) and bovine saliva, whereas for equine saliva 0.94mM was needed. ADA2 activity was not detected in bovine serum and was very low or absent in equine serum and bovine saliva. An automated procedure to measure ADA2 consisting of adding EHNA to a commercial reagent for tADA measurement provided repetitive (coefficients of variation <8.8% in serum and <10% in saliva) and accurate (linearity under dilution approaches gave R 2 >0.90) results, being equivalent to a manual incubation of the sample with EHNA at a similar concentration. Salivary tADA, as well as ADA1 and ADA2, were higher in dogs with leishmaniosis, horses with acute abdominal disease and pigs with lameness than in healthy animals. ADA showed significant correlation with serum ferritin in dogs ( r = 0.602, P <0.01; r = 0.555, P <0.05; and r = 0.632, P <0.01; respectively for tADA, ADA1 and ADA2) and serum C-reactive protein in pigs ( r = 0.700, P <0.01, for both tADA and ADA1; r = 0.770, P <0.001, for ADA2), whereas salivary ADA2 significantly correlated with serum amyloid A in the horse ( r = 0.649, P <0.01). In the cow, salivary tADA and ADA1 significantly increased after calving, correlatingd with total white blood cell count ( r = 0.487, P <0.05, both).Conclusions: ADA activity, as well as its isoenzymes, can be measured in serum and saliva of different animal species. The salivary levels of these analytes could potentially be inflammatory biomarkers in these species.

Changes of adenosine deaminase activity in serum and saliva around parturition in sows with and without postpartum dysgalactia syndrome

“…The significant associations between salivary ADA1, ADA2 and other inflammatory markers corroborate that these isoenzymes are indeed markers of inflammation in sows. This is in agreement with previous studies showing an increased salivary ADA activity in pigs undergoing inflammatory processes [22,23]. The role of the adenosine pathway in the inflammatory process has been fully explored in humans in several diseases such as asthma, arthritis, sepsis [41], colitis [42] or spinal cord injury [43].…”

“…Although serum ADA2 showed a strong trend to differ between PDS+ and PDS-sows, statistically this marker appears unsuitable for the use in the diagnosis of PDS. The relation between serum ADA and inflammation is, however, not entirely clear, as although Fávero et al [36] demonstrated increased ADA activities in cows at the end of pregnancy and after calving, other reports were not able to demonstrate any increase in serum ADA during inflammatory conditions [22,23]. Increased serum ADA activity at the end of gestation and in the periparturient period may be explained by two mechanisms.…”

“…ADA activity was more than 100-fold higher in pig saliva than in serum. In addition, since a correlation between salivary ADA and serum ADA seems to be absent, it is possible that ADA, sampled from the oral cavity, could provide information that differ from that of ADA from serum [23]. Thus, ADA in saliva may be expected to be a useful marker of inflammation in pigs.…”