Acute phase response in experiments with simulated weightless environment

Abstract

The study of acute phase response (APR) induced by extreme impacts enables to obtain new data on adaptive events in altered environmental conditions. APR is an innate nonspecific systemic protective reaction caused by inflammation, which is characterized by changes in hepatic synthesis of blood proteins named acute phase proteins. A series of experiments with dry immersion were conducted to measure plasma concentrations of acute phase proteins as markers of APR development. The aim of the work was to study the indices of APR development during adaptation to immersion based on the results of statistic analysis of samples of plasma concentrations of acute phase proteins obtained in a series of immersion experiments. The surveyed sample included male subjects, aged 18–48 (28.1±6.1), height 1.76±0.05 m, weight 71.8±9.1 kg, body mass index 23.0±2.4. Throughout the first four days of immersion, the immunoturbidimetric method was used to measure plasma concentrations of positive acute phase proteins α1-antitrypsin (α1-AT), α1-acid glycoprotein (α1-AGP), ceruloplasmin (Cer), haptoglobin (Hp), and α2-macroglobulin (α2-M). With the exception of ceruloplasmin, there was a reliable increase in protein levels. An increase in average protein levels became noticeable on the second immersion day. The highest increment in average concentration amounted to 40% (α1-AT), 16% (α1-AGP), 37% (Hp), and 43% (α2-M). The acute phase protein synthesis showed considerable variation between individuals. The above effects evidence APR development as an adaptation to immersion. The transition to simulated weightlessness causes considerable disruption of the body’s homeostatic equilibrium which evokes additional nonspecific defense mechanisms besides the stress response.