Сongenital immunity dysfunction in patients with postoperative cognitive impairment after coronary artery bypass grafting

With regard of post-surgical cognitive disturbances, an active search for biological markers of these neurological complications is performed. We have studied the contents of NSE, IL-6, TGF-β1, MMP9 and TIMP1 in blood serum of these patients. The study included 110 patients after aortal-coronary bypass surgery using extracorporeal blood circulation. Splitting into separate groups was based on the test scores, according to Montreal Cognitive Assessment Scale prior to surgery and on day +7 after the intervention: (I) patients without complications (< 3 points); (II) patients with post-surgical cognitive impairment (> 3 points). The comparison group (III) included 35 healthy subjects. Evaluation of NSE, IL-6, TGF-β1, ММP9 and TIMP1 in blood serum was performed by means of ELISA technique (R&D Systems, USA). The data were expressed as pg/ml, or ng/ml. Blood sampling was made at 4 terms: before surgery, just after intervention, 24 h later, and on day 7 after the surgery.
The patients from group II showed higher NSE levels, except of 7 days after surgery when it became similar to other groups. Increased IL-6 levels were found in the patients from group II at all terms after surgery. Decreased concentration of TGF-β1 was found in the II group prior to operation, 24 h and 7 days after the surgery. However, just after surgery, this index was increased, and its values barely differed from results of groups I and III. Studies of MMP9 showed significant differences between groups I and II only on day +7 after. However, lower MMP9 content was detected in the patients from I and II groups before surgery compared to group III. TIMP1 values showed gradual increase over the observation period, but did not differ between groups I and II. In the patients from group II, an increased content of NSE and IL-6 was revealed, along with low TGF-β1 levels and decreased ММP9/TIMP1 ratio over early postsurgical period, thus suggesting possible role of innate immunity dysfunction in pathogenesis of postsurgical cognitive impairment.