Downloaded from http://journals.lww.com/shockjournal by BhDMf5ePHKbH4TTImqenVAHxkFJp/XpPk1L/H3vMGwqMxG9jwOd8eHu+WdxxmltmG+Y2f0aqIM4= on 07/30/2018 BONE MARROW FAILURE IN MALE RATS FOLLOWING TRAUMA/ HEMORRHAGIC SHOCK (T/HS) IS MEDIATED BY MESENTERIC LYMPH AND MODULATED BY CASTRATION Ziad C. Sifri, Vicki L. Kaiser, Preya Ananthakrishnan, Lai Wang, Alicia M. Mohr, Carl J. Hauser, Pranela Rameshwar, Edwin A. Deitch, and David H. Livingston Division of Trauma, Department of Surgery, New Jersey Medical School, Newark, New Jersey 07103 Received 15 Jul 2005; first review completed 1 Aug 2005; accepted in final form 19 Sep 2005 ABSTRACT—Bone marrow (BM) suppression occurs following trauma/hemorrhagic shock (T/HS) in experimental animals as well as following severe injury in humans. Although the pathophysiology of BM suppression remains poorly understood, mesenteric lymph is thought to play an important role in T/HS-induced BM suppression; however, the direct effect of mesenteric lymph on BM in vitro has never been studied. In addition, recent studies in rats have also shown that female and castrated male rats are protected against T/HS-induced BM failure. We therefore hypothesized that mesenteric lymph is a source of factor(s) causing direct BM suppression and that the effects of mesenteric lymph are gender dependent. To test this hypothesis, we subjected noncastrated (NC) and castrated (C) male and proestrus female rats to T/HS or trauma sham shock (T/SS). Mesenteric lymph collected 3 h postshock was plated (4% v/v) with BM cells collected from unmanipulated male or female rats for granulocyte-macrophage colony-forming units (CFU-GM) and erythroid burst-forming units (BFU-E) colony growth. The T/HS lymph collected from NC-male rats but not from female rats caused a 50% inhibition of CFU-GM and BFU-E colony growth compared with cells cultured without lymph (P < 0.05 versus all other groups (ANOVA + Tukey). T/HS lymph collected from C-male rats also caused no significant inhibition of CFU-GM and BFU-E colony growth compared with cells cultured without lymph. Female and male BM progenitor cells had a similar response to mesenteric lymph from all groups tested. These results show that mesenteric lymph from NC-male rats suppresses CFU-GM and BFU-E progenitor growth in vitro, whereas the lymph from C-male and female rats did not. The effects of mesenteric lymph were the same regardless of whether the target BM was from male or female rats. The results therefore indicate that BM failure in male rats is directly mediated by factors present within the mesenteric lymph that appear to be modulated by castration, and protection against BM failure in female rats occurs at a systemic rather than a local level. Further studies are needed to elucidate potential therapeutic effects of lymph manipulation in hematopoiesis after injury. KEYWORDS—Castration, trauma, hemorrhagic shock, bone marrow suppression, progenitor cells, hematopoiesis, CFU-GM, BFU-E INTRODUCTION Multiple organ failure, which includes bone marrow (BM) failure, occurs following major traumatic injuries and hemor- rhagic shock in humans (1–3). Little is known about the pathophysiology of BM failure, and as a result, very few therapeutic modalities are currently available for use in crit- ically injured trauma patients. BM failure is manifested clin- ically by a persistent anemia and an increased susceptibility to infection and sepsis mainly as a result of the BM’s essential role in erythropoiesis and myelopoiesis, respectively. Dysfunc- tion in erythropoiesis is primarily related to a quantitative defect in RBC production at the level of marrow that is unrelated to iron stores or erythropoietin (1). In contrast, it is thought that the increased risk of infection is more related to qualitative changes in granulocyte functional maturation. Recently we described the extent of BM failure following severe injury in humans (1), which includes a decrease in progenitor cell growth, impaired growth of BM stroma, and an increased release of BM progenitor cells into the circulation. The data parallel our previous studies using a well- established male rodent model of trauma/hemorrhagic shock (T/HS). In fact, T/HS causes BM suppression in vivo in male rats as early as 3 h post-T/HS, but the exact mechanism of BM inhibition in this animal model remains poorly understood. Recent work using this rat model has demonstrated that lymph- duct ligation (LDL) before T/HS protects against BM suppression in male rats as well as other end-organ damage, indicating that mesenteric lymph plays an important role in T/HS-induced BM suppression (4, 5). In addition, T/HS mesenteric lymph has been shown to be toxic to endothelial cells and to activate neutrophils in vitro (6, 7). However, no studies have yet been done to determine the direct effect of mesenteric lymph on BM hematopoietic function. We hypoth- esize that T/HS mesenteric lymph directly inhibits progenitor clonogenic growth via factors present in T/HS lymph. Gender has also been shown to affect the response to T/HS and the extent of end-organ damage. Recent studies utilizing the same model have shown that female animals appear to be more protected against the effects of T/HS and manifest less gut and lung injury following T/HS than do male animals (8– 10). We have also recently shown in our laboratory that female rats are resistant to T/HS-induced BM failure and that castration protected male rats against T/HS-induced BM failure in vivo (Sifri, unpublished data, 2005). Because the beneficial effect of the female gender appears to be global, Address reprint requests to Ziad C. Sifri, MD, University Hospital M229, 150 Bergen Street, Newark, NJ 07103. E-mail: sifrizi@umdnj.edu. DOI: 10.1097/01.shk.0000188708.97153.ce Copyright Ó 2006 by the Shock Society 12 SHOCK, Vol. 25, No. 1, pp. 12–16, 2006 Copyright ' Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.