The Relationship Between LPS-induced Thrombocytopenia With DIC

Objective:To establish thrombocytopenia mice models by intraperitoneal injection of LPS, then to observe the effect of different doses of LPS on platelet counts (PLT). To determine the relationship between LPS-induced thrombocytopenia with platelet production by detecting MPV and plasma TPO levels. To investigate the effect of coagulation system in thrombocytopenia by plasma TAT, D-dimer and FDPs levels. To investigate the pathological change in various organs and its relationship with DIC in LPS-induced thrombocytopenia.Methods:This study was divided into two parts.The first part:To establish thrombocytopenia mice models. Seventy-five C57BL/6mice (SPF level, male,8～10weeks,18-22g) were randomized into five groups:normal saline control (group C), low dose LPS (group L), medium dose LPS (group M), high dose LPS (group H) and extremely high dose LPS (group S). Mice in five groups were intraperitoneally injected with normal saline0.005ml/g, LPS0.05,0.5,5and50mg/kg, respectively. The reaction to LPS and the time of death were recorded, blood samples were collected on each time point to test PLT.The second part:To observe the effects of difference doses of LPS on platelet production and coagulation system. C57BL/6mice were randomized into five groups: normal saline for4h and24h (groups C1and C2), low dose LPS for4h and24h (0.5mg/kg, groups LL4and LL24), high dose LPS for4h and24h (50mg/kg, groups HL4and HL24). Mice in groups C1, C2, LL4, LL24, HL4, and HL24were killed and blood samples were collected4,24,4,24,4,24h following injection, respectively. Blood cell counts, plasma TPO, D-dimer, TAT and FDPs levels were determined. The intestine and lung tissue were removed and stained with HE to observe the histopathological changes and assess the tissue pathological score.Results:The C57BL/6mice were sensitive to injection of LPS. Thrombocytopenia can be induced2h after low dose LPS (0.05mg/kg) injection, and the degree was increased with the increment of LPS. With extremely high dose LPS (50mg/kg), the72h mortality was over70%. The PLT in group L, M and H began to increase8,24,24h after injection and normalized in24,72,72h, respectively. But in group S, the PLT decreased without any return.Four h after LPS injection, the PLT and WBC in groups LL4and HL4were significantly lower than in group C1(P<0.05); the MPV in groups LL4and HL4were slightly higher than in group C1(P>0.05); the TPO, D-dimer and FDPs levels were not different (P>0.05); the TAT levels in groups LL4and HL4were significantly lower than in group C1(P<0.05). The tissue injury scores of intestine and lung in groups LL4and HL4were significantly higher than in group Cl (P<0.05), and the score in group HL4were significantly higher than in group LL4(P<0.05).Twenty-four h after LPS injection, the PLT and WBC counts in groups LL24and HL24were significantly lower than in group C2(P<0.05); the MPV in groups LL24and HL24were significantly higher than in group C2(P<0.05); the TPO, D-dimer and FDPs levels were not different (P>0.05); the TAT levels in groups LL24and HL24were significantly lower than in group C2(P<0.05). The tissue injury scores of intestine and lung in group HL24were significantly higher than in group LL24(P<0.05), and in both groups were significantly higher than in group C2(P<0.05).Conclusions:1. The C57BL/6mice are sensitive to LPS injection, thrombocytopenia can be induced2h after low dose LPS (0.05mg/kg) injection, and the degree was increased with the increment of LPS. When given extremely high dose LPS (50mg/kg), the72h mortality was70%.2. LPS-induced thrombocytopenia is caused by accelerated platelet clearance rather than diminished production.3. LPS-induced thrombocytopenia in mouse model is not related to DIC.