Alamo Ines G, Kannan Kolenkode B, Loftus Tyler J, Ramos Harry, Efron Philip A, Mohr Alicia M
From the Department of Surgery and Center for Sepsis and Critical Illness Research (I.G.E., K.B.K., T.J.L., H.R., P.A.E., A.M.M.), University of Florida College of Medicine, Gainesville, Florida.
J Trauma Acute Care Surg. 2017 Jul;83(1):144-150. doi: 10.1097/TA.0000000000001537.
Severe traumatic injury is associated with bone marrow dysfunction that manifests as impaired erythropoiesis and prolonged hematopoietic progenitor cell (HPC) mobilization from the bone marrow. Extramedullary erythropoiesis, the development of red blood cells outside the bone marrow, has not been studied after severe injury and critical illness. This study examined the influence of lung contusion/hemorrhagic shock (LCHS) followed by chronic stress (CS) on the rodent spleen and to investigate the involvement of the splenic erythropoietin (EPO)/EPO receptor and BMP4 signaling.
Male Sprague-Dawley rats were subjected to LCHS and LCHS/CS. Animals underwent 2 hours of daily restraint stress until the day of sacrifice. On day 7, the spleen was assessed for weight, growth of splenic colony-forming units (CFU)-granulocyte-, erythrocyte-, monocyte- megakaryocyte (GEMM), burst-forming unit-erythroid (BFU-E), and CFU-E colonies, the presence of HPCs, and splenic mRNA expression of bone morphogenetic protein 4 (BMP4), EPO and its receptor. Data were presented as mean ± SD; *p < 0.05 vs. naïve and **p < 0.05 vs. LCHS by t test.
On day 7, the addition of CS to LCHS increased spleen weight by 22%. LCHS/CS increased splenic growth of CFU-GEMM, BFU-E, and CFU-E colonies by 28% to 39% versus LCHS alone. Seven days after LCHS/CS, splenic HPCs increased from 0.60% to 1.12 % compared with naïve animals. After LCHS/CS, both BMP4 and EPO expression increased significantly in the spleen. Splenic EPO receptor (EPOr) expression decreased after LCHS/CS in the presence of a persistent moderate anemia.
Extramedullary erythropoiesis, manifest by increased splenic weight, splenic erythroid colony growth, splenic HPCs, BMP4, and EPO expression, is present in the spleen after LCHS/CS. Splenic EPOr expression was significantly decreased after LCHS/CS. Extramedullary erythropoiesis may play a key role in identifying new therapies to aid the recovery from acute anemia after severe trauma and chronic stress.
严重创伤性损伤与骨髓功能障碍相关，表现为红细胞生成受损以及造血祖细胞（HPC）从骨髓中动员的时间延长。骨髓外红细胞生成，即骨髓外红细胞的发育，在严重损伤和危重病后尚未得到研究。本研究考察了肺挫伤/失血性休克（LCHS）后继发慢性应激（CS）对啮齿动物脾脏的影响，并探究脾脏促红细胞生成素（EPO）/EPO受体和骨形态发生蛋白4（BMP4）信号通路的参与情况。
将雄性Sprague-Dawley大鼠分为LCHS组和LCHS/CS组。动物每天接受2小时的束缚应激，直至处死当天。在第7天，评估脾脏的重量、脾集落形成单位（CFU）-粒细胞、红细胞、单核细胞、巨核细胞（GEMM）、爆式红细胞集落形成单位（BFU-E）和CFU-E集落的生长情况、HPC的存在情况以及脾脏中骨形态发生蛋白4（BMP4）、EPO及其受体的mRNA表达。数据以平均值±标准差表示；通过t检验，与未处理组相比，*p < 0.05，与LCHS组相比，**p < 0.05。
在第7天，LCHS组加用CS使脾脏重量增加了22%。与单独的LCHS组相比，LCHS/CS组使CFU-GEMM、BFU-E和CFU-E集落的脾脏生长增加了28%至39%。与未处理动物相比，LCHS/CS后7天，脾脏HPC从0.60%增加到1.12%。LCHS/CS后，脾脏中BMP4和EPO的表达均显著增加。在持续中度贫血的情况下，LCHS/CS后脾脏EPO受体（EPOr）表达降低。
LCHS/CS后脾脏出现骨髓外红细胞生成，表现为脾脏重量增加、脾脏红系集落生长、脾脏HPC、BMP4和EPO表达增加。LCHS/CS后脾脏EPOr表达显著降低。骨髓外红细胞生成可能在确定辅助严重创伤和慢性应激后急性贫血恢复的新疗法中起关键作用。
