Objective: To observe the changes of serum complements and proinflammatory cytokines in rats with sepsis, and to explore the possible mechanism.
Methods: 120 healthy male Wistar rats were randomly divided into three groups: normal control group (n = 15), sham operation group (n = 15) and sepsis group [cecum ligation and puncture (CLP) operation, n = 90]. The sepsis rats were sacrificed on 24, 48 and 72 hours after modeling. The level of serum complements (C5, C5a) and cytokines tumor necrosis factor-α (TNF-α), interleukin (IL-1, IL-6), high mobility group box 1 (HMGB1), macrophage migration inhibitory factor (MIF) were detected by enzyme linked immunosorbent assay (ELISA).
Results: Compared with normal control group and sham operation group, the levels of serum complements C5, C5a and IL-1β were significantly increased at 24 hours after CLP in sepsis group [C5 (ng/L): 1.60±0.19 vs. 1.04±0.20, 1.09±0.09; C5a (ng/L): 0.20±0.02 vs. 0.18±0.01, 0.18±0.02; IL-1β (ng/L): 700.20±111.41 vs. 475.87±108.96, 592.29±121.57; all P < 0.05]; then the levels of C5, C5a and IL-1β declined, the level of serum C5 were also higher than normal control group at 48 hours and 72 hours after CLP (ng/L: 1.17±0.24, 1.27±0.24 vs. 1.04±0.20, both P < 0.05). In sepsis group the level of serum TNF-α (ng/L: 51.33±1.96, 51.06±1.64) was lower than that in normal control group (59.53±3.06) and sham operation group (57.91±2.72) at 48 hours and 72 hours (all P < 0.05). There was a time dependent rise of serum HMGB1 in sepsis group, which level was much higher than that in normal control group and sham operation group at 72 hours after CLP (ng/L: 472.21±20.94 vs. 406.00±43.16, 404.41±35.39, both P < 0.05). There were no significant differences of MIF, and IL-6 level between groups at each time points.
Conclusions: Complement system led to uncontrolled inflammatory response and immune dysfunction through the release of proinflammatory cytokines and inflammatory mediators, which maybe one of the important mechanism of the pathology of sepsis.