Hypertonic saline resuscitation of hemorrhagic shock diminishes neutrophil rolling and adherence to endothelium and reduces in vivo vascular leakage

OBJECTIVE: To evaluate the in vivo effects of hypertonic saline (HTS) resuscitation on the interactions of endothelial cells (ECs) and polymorphonuclear neutrophils (PMNs) and vascular permeability after hemorrhagic shock. SUMMARY BACKGROUND DATA: The PMN has been implicated in the pathogenesis of EC damage and organ injury following hemorrhagic shock. Compared to Ringer's lactate (RL), HTS resuscitation diminishes PMN and EC adhesion molecule expression and organ sequestration of PMNs. METHODS: In a murine model of hemorrhagic shock (50 mmHg for 45 minutes followed by resuscitation) using intravital microscopy on cremaster muscle, the authors studied PMN-EC interactions and vascular leakage (epifluorescence after 50 mg/kg fluorescent albumin) in three resuscitation groups: HTS (shed blood + 4 cc/kg 7.5% HTS, n = 12), RL (shed blood + RL [2x shed blood volume], n = 12), and sham (no hemorrhage or resuscitation, n = 9). EC ICAM-1 expression was evaluated by immunohistochemistry. Data, presented as mean +/- SEM, were evaluated by analysis of variance with Bonferroni correction. RESULTS: There were no differences between groups in flow mechanics. Compared to RL, HTS animals (t = 90 minutes) displayed diminished PMN rolling and PMN adhesion to EC at time intervals beyond t = 0. There were no differences between the sham and HTS groups. Vascular leakage was 45% lower in HTS than in RL-resuscitated animals. Cremaster EC ICAM-1 expression was similar in the two groups. CONCLUSIONS: Using HTS instead of RL to resuscitate hemorrhagic shock diminishes vascular permeability in vivo by altering PMN-EC interactions. HTS could serve as a novel means of immunomodulation in hemorrhagic shock victims, potentially reducing PMN-mediated tissue injury.     

Neutrophil CD18 expression and blockade after traumatic shock and endotoxin challenge.

OBJECTIVE: The expression of the leukocyte CD18 adhesion complex on polymorphonuclear leukocytes (PMNs) was measured, and the physiologic effects of blockade of the complex were studied after trauma and sepsis. SUMMARY BACKGROUND DATA: Margination of PMNs occurs early during inflammation and depends, in part, on expression of the CD18 adhesion complex. Blockade of this adherence complex can reduce PMN-mediated damage. This study tests the hypothesis that PMN activation after resuscitated trauma produces an occult endothelial injury that increases the vulnerability to a delayed inflammatory stimulus. METHODS: Anesthetized (fentanyl) mongrel pigs were sham injured or fluid resuscitated from soft tissue injury +35% hemorrhage. Systemic blood was collected at 24-hour intervals from awake animals. The CD18 density on circulating PMNs was determined with flow cytometry using mean channel fluorescence (MCF). The CD18 receptors were blocked with monoclonal antibodies either immediately before trauma or immediately before an endotoxin (lipopolysaccharide [LPS]) challenge that was administered to all groups 3 days after the shock episode. Bronchoscopy was performed before trauma, pre-LPS, and post-LPS, and protein content was measured in bronchoalveolar lavage (BAL). RESULTS: Mean channel fluorescence was reduced on PMNs for 48 hours in animals with trauma versus animals with sham injuries. Anti-CD18 therapy produced higher circulating PMN counts compared with nontreated sham or shock groups. The incremental rise of BAL protein after shock was prevented with anti-CD18; the increment after LPS was attenuated. Anti-CD18 was administered before trauma and reduced the fluids necessary to maintain cardiac filling pressures after LPS. CONCLUSIONS: These data suggest that PMNs are activated after resuscitation from traumatic shock and that these cells produce an endothelial injury that may increase the vulnerability to a septic challenge. The broad implication is that temporarily blocking PMN adhesiveness at the time of trauma might salvage some host tissue and reduce the incidence of septic complications in the post-trauma period.     

Hypertonic saline resuscitation attenuates neutrophil lung sequestration and transmigration by diminishing leukocyte-endothelial interactions in a two-hit model of hemorrhagic shock and infection

BACKGROUND: Hypertonic saline (HTS) attenuates polymorphonuclear neutrophil (PMN)-mediated tissue injury after hemorrhagic shock. We hypothesized that HTS resuscitation reduces early in vivo endothelial cell (EC)-PMN interactions and late lung PMN sequestration in a two-hit model of hemorrhagic shock followed by mimicked infection. METHODS: Thirty-two mice were hemorrhaged (40 mm Hg) for 60 minutes and then given intratracheal lipopolysaccharide (10 microg) 1 hour after resuscitation with shed blood and either HTS (4 mL/kg 7.5% NaCl) or Ringer's lactate (RL) (twice shed blood volume). Eleven controls were not manipulated. Cremaster intravital microscopy quantified 5-hour EC-PMN adherence, myeloperoxidase assay assessed lung PMN content (2 1/2 and 24 hours), and lung histology determined 24-hour PMN transmigration. RESULTS: Compared with RL, HTS animals displayed 55% less 5-hour EC-PMN adherence (p = 0.01), 61% lower 24-hour lung myeloperoxidase ( p= 0.007), and 57% lower mean 24-hour lung histologic score ( p= 0.027). CONCLUSION: Compared with RL, HTS resuscitation attenuates early EC-PMN adhesion and late lung PMN accumulation in hemorrhagic shock followed by inflammation. HTS resuscitation may attenuate PMN-mediated organ damage.     

Hypertonic resuscitation modulates the inflammatory response in patients with traumatic hemorrhagic shock

OBJECTIVE: To determine the effect of resuscitation with hypertonic saline/dextran (HSD) on the innate immune response after injury. SUMMARY OF BACKGROUND DATA: Hypovolemic shock causes a whole body ischemia/reperfusion injury, leading to dysregulation of the inflammatory response and multiple organ dysfunction syndrome. Hypertonicity has been shown to modulate the innate immune response in vitro and in animal models of hemorrhagic shock, but the effect on the inflammatory response in humans is largely unknown. METHODS: Serial blood samples were drawn (12, 24, 72 hours and 7 days after injury) from patients enrolled in a prospective, randomized, double-blind trial of traumatic hypovolemic shock, HSD (250 mL) versus lactated Ringer's solution (LR) as the initial resuscitation fluid. Neutrophil (PMN) CD11b/CD18 expression was assessed via whole blood FACS analysis with and without stimulation (fMLP 5 micromol/L or PMA 5 micromol/L). PMN respiratory burst was assessed using the nitro-blue tetrazolium assay. Monocytes stimulated with 100 ng LPS for 18 hours were assessed for cytokine production (TNF-alpha, IL-1Beta, IL-6, IL-10, IL-12). RESULTS: Sixty-two patients (36 HSD, 26 LR) and 20 healthy volunteers were enrolled. CD11b expression, 12 hours after injury, was increased 1.5-fold in patients resuscitated with LR compared with controls. Those resuscitated with HSD had a significant reduction in CD11b expression 12 hours after injury, compared with LR. There was no difference in respiratory burst early after injury. Monocytes from injured patients expressed lower levels of all cytokines in comparison to normal controls. Patients give HSD showed a trend toward higher levels of IL-1beta and IL10 production in response to LPS, 12 hours after injury. CONCLUSION: HSD resuscitation results in transient inhibition of PMN CD11b expression and partial restoration of the normal monocyte phenotype early after injury.     

Hypertonic immunomodulation is reversible and accompanied by changes in CD11b expression.

BACKGROUND: In a two-hit model of hemorrhagic shock and lipopolysaccharide (LPS), we previously showed that hypertonic saline (HTS) resuscitation reduced lung sequestration of neutrophils and the accompanying injury. This effect was partially attributed to suppressed expression of the surface adhesion molecule CD11b. This study investigates the duration of this protective effect after a single HTS dose and the usefulness of repeated infusions. MATERIAL AND METHODS: The previous two-hit rodent model was used. Neutrophil lung sequestration was measured by bronchoalveolar fluid cell count. CD11b expression was followed by flow cytometry. In vitro studies used isolated human neutrophils. RESULTS: Eighteen hours following resuscitation, the protective effect of HTS was lost. At this time, LPS caused an increase in both neutrophil lung sequestration and CD11b expression, regardless of the resuscitation regimen used. A second infusion of HTS prevented these changes and restored the lung protection observed earlier. In vitro studies showed that the duration of hypertonic pretreatment is an important determinant of cell responsiveness under the isotonic conditions: Four but not 2 h hypertonic exposure was able to prevent upregulation of CD11b induced by LPS added immediately after reestablishing isotonicity. CONCLUSIONS: This study demonstrates that HTS resuscitation lessens lung neutrophil sequestration and CD11b surface expression induced by LPS. This protective effect is transient but can be restored by a second HTS infusion suggesting that maintenance of beneficial effect necessitates repeated HTS addition. The reversibility ensures rapid modulation of neutrophil functions, thereby preventing acute tissue damage without causing long-lasting immunosuppression.     

Changes of pulmonary intercellular adhesion molecule-1 and CD11b／CD18 in peripheral polymorphonuclear neutrophils and their significance at the early stage of burns

Objective: To investigate the role of intercellular adhesion molecule-1 (ICAM-1) in the accumulation of polymorphonuclear neutrophils (PMN) in the lungs at the early stage of burns. Methods: Myeloperoxidase content in lung tissues and bronchoalveolar lavage fluid (BALF) were detected.ICAM-1 and its mRNA expression in lung tissues were determined bycal method and in situ hybridization. CD11b/CD18 expression on the peripheral PMNs was measured by flowcytometry. Results : The levels of myeloperoxidase in lung tissues and BALF after burn injury were markedly higher than those of control. Expression of ICAM-1 and its mRNA in the lung tissues and CD11b/CD18 on peripheral PMNs surface was significantly increased at 2, 6, 12, 24 h after burns. Conclusions. PMNs accumulation in the lungs is related to increased ICAM-1 expression on pulmonary microvascular endothelial cells and CD11b/CD18 expression on PMN at the early stage of burn injury.     

Protective effect of albumin on lung injury in traumatic/hemorrhagic shock in rats

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Protective effect of albumin on lung injury in traumatic/ hemorrhagic shock rats

Objective. To determine the effect of albumin administration on lung injury in traumatic/hemorrhagic shock （T/HS） rats. Methods： Forty-eight adult Sprague-Dawley rats were divided into three groups randomly （ n = 16 in each group） ： Group A, Group B, Group C. In Group A, rats underwent laparotomy without shock. In Group B, rats undergoing T/HS were resuscitated with their blood plus lactated Ringer＇s （twice the volume of shed blood ）. In Group C, rats undergoing T/HS were resuscitated with their shed blood plus additional 3 ml of 5% human albumin. The expression of polymorphonuclear neutrophils CD18/CD11b in jugular vein blood was evaluated. The main lung injury indexes （the activity of myeloperoxidase and lung injury score） were measured. Results： Significant differences of the expression of CD18/11b and the severity degree of lung injury were found between the three groups. （P〈0.05）. The expression of CD18/CD11b and the main lung injury indexes in Group B and Goup C incresed significantly compared with those in Group A （P 〈0.05）. At the same time, the expression of CD18/CD11b and the main lung injury indexes in Group C decreased dramatically, compared with those in Group B （ P 〈0.05 ）. Conclusions ： The infusion of albumin during resuscitation period can protect lungs from injury and decrease the expression of CD18/CD11b in T/HS rats.     

Pentoxifylline reduces acute lung injury in chronic endotoxemia

BACKGROUND: Pentoxifylline (PTX) attenuates end-organ injury in models of sepsis and hemorrhage. PTX is thought to act by inhibiting phosphodiesterase, thus increasing cAMP and decreasing tumor necrosis factor-alpha (TNF-alpha) synthesis. The effects of PTX on neutrophil and endothelial cell adhesion molecules and, ultimately, organ injury in a chronic endotoxemia model have not been studied. We hypothesized that continuous infusion of PTX reduces acute lung injury (ALI) caused by chronic lipopolysaccharide (LPS) exposure. MATERIALS AND METHODS: Male Sprague-Dawley rats were given continuous infusion of LPS, PTX + LPS combined, or saline (sham) by implantable pumps. Neutrophil CD11b expression, lung histopathology, lung intercellular adhesion molecule-1 (ICAM-1) expression assessed by immune staining, serum TNF-alpha, serum interleukin-6 (IL-6), and bronchoalveolar lavage (BAL) IL-8 were evaluated at different time points. Lung injury was graded in a blinded fashion from 0 (normal) to 4 (severe) for interstitial inflammation, neutrophil infiltration, congestion, and edema. Total lung injury score (TLIS) was calculated by adding listed categories. White cell count in the peripheral blood and in the BAL was also performed. RESULTS: Animals treated with PTX + LPS showed a significant reduction in lung injury score, a marked decrease in ICAM-1 expression, and a significant decrease in IL-8 levels in the BAL and serum IL-6 levels when compared with LPS-treated animals. CONCLUSIONS: Continuous infusion of PTX reduces ALI caused by chronic endotoxemia. The effect seems to be a result of decreased expression of endothelial and epithelial ICAM-1 and modulation of proinflammatory cytokine synthesis.     

Functional and phenotypic changes in polymorphonuclear neutrophils induced by catecholamines

PURPOSE: To elucidate differential functional and phenotypic changes in response to relevant catecholamines, the generation of oxidative free radicals by PMN, and changes in the expression of L-selectin and Mac-1 on the surface of PMN were examined in the presence of epinephrine, norepinephrine and dopamine in physiological and pharmacological concentrations. MATERIALS AND METHODS: Human polymorphonuclear neutrophils were obtained from healthy donors and pretreated with 0.5 nM or 500 nM epinephrine; 1.18 nM or 1 180 nM norepinephrine; or 0.26 nM or 261 nM dopamine, followed by stimulation with FMLP. Stimulated neutrophils were incubated with antibodies against CD 11 b or CD 62 l and assessed by flow cytometry. Additional probes were assessed by flow cytometry for the generation of oxidative free radicals. RESULTS: All catecholamines in high concentration inhibited the suppression of CD 62 l expression and CD 11 b upregulation following stimulation with FMLP. A high concentration of epinephrine suppresses generation of oxidative free radicals. CONCLUSIONS: The effect of catecholamines on the expression of CD 62 l explains the increased expression of L-selection on PMN observed after trauma. The suppression of CD 11 b reduces leukocyte adherence and consecutive abnormalities in microvascular flow. Epinephrine inhibits the generation of oxidative free radicals by PMN with potentially detrimental effects with respect to bacterial clearance.     

Hypertonic saline and pentoxifylline reduces hemorrhagic shock resuscitation-induced pulmonary inflammation through attenuation of neutrophil degranulation and proinflammatory mediator synthesis

BACKGROUND: Ringer's lactate (RL), the current standard resuscitation fluid, potentiates neutrophil activation and is associated with pulmonary inflammation. Resuscitation with hypertonic saline and pentoxifylline (HSPTX) has been shown to attenuate hemorrhagic shock-induced injury when compared with RL. Because the neutrophil plays a major role in postshock inflammation, we hypothesized that HSPTX reduces pulmonary inflammation after resuscitation in comparison to RL. METHODS: Sprague-Dawley rats underwent controlled shock and were resuscitated with RL (32 mL/kg) or HSPTX (4 mL/kg 7.5% NaCl + pentoxifylline 25 mg/kg). Animals who did not undergo shock or resuscitation served as controls. After 24 hours, bronchoalveolar lavage fluid (BALF) and lung tissue were collected. Cytokine induced neutrophil chemoattractant (CINC) was measured in BALF by enzyme-linked immunosorbent assay. Matrix metalloproteinases (MMP)-2 and -9 were measured by zymography. Hemeoxygenase-1 (HO-1) was assessed by Western blot and immunohistochemistry. RESULTS: HSPTX resuscitation led to a 62% decrease in CINC levels compared with RL (p < 0.01). BALF MMP-2 expression was attenuated by 11% with HSPTX (p = 0.09). Lung MMP-2 and MMP-9 expression was reduced by 89% (p < 0.01) and 76%, respectively (p < 0.05). Lung HO-1 expression declined by 34% with HSPTX in comparison to RL (p < 0.01), indicating less oxidative injury. Lung immunohistochemistry localized HO-1 to neutrophils, macrophages, and airway epithelial cells. CONCLUSION: Collectively, the attenuation of pulmonary inflammation with HSPTX after shock when compared with RL is associated with downregulation of neutrophil activation, oxidative stress, and proinflammatory mediator production.     

Attenuated expression of inducible nitric oxide synthase in lung microvascular endothelial cells is associated with an increase in ICAM-1 expression

BACKGROUND/PURPOSE: The molecular and cellular events that regulate inflammatory lung injury, a major cause of morbidity in surgical patients, remain unclear. The authors hypothesize that nitric oxide (NO) plays an important role in regulating polymorphonuclear cell (PMN)-induced acute lung injury, and further, that attenuated expression of inducible nitric oxide synthase (iNOS) and therefore decreased production of NO by lung microvascular endothelial cells (LMVEC), accelerates inflammation and injury. METHODS: LMVEC and aortic EC (AEC) from rat and human were stimulated with lipopolysaccharide (LPS) and cytokines; changes in iNOS mRNA expression and iNOS activity were determined. The role of NO in mediating inflammatory responses was evaluated by determining PMN adherence to LMVEC and lung tissue slices in the presence and absence of NOS inhibitors and NO donors. Human LMVEC and AEC were assessed by FACS analysis for ICAM-1 expression, because this is thought to be a critical determinant of PMN adherence. RESULTS: When stimulated with endotoxin and cytokines, rat AEC monolayers express nearly 3-fold more iNOS mRNA than rat LMVEC. The low levels of LMVEC iNOS expression are associated with a 4-fold lower nitrite and nitrate production. Similar trends are seen in human endothelial cells. When iNOS activity was blocked, PMN adherence to tumor necrosis factor alpha (TNFalpha)/LPS-stimulated LMVEC was markedly increased. In contrast, adding a nitric oxide donor to endotoxin/cytokine-stimulated LMVEC monolayers reduced PMN adherence to near background levels. Similar responses were observed in vivo. Human lung microvascular endothelial cells show a substantially increased level of ICAM-1 upregulation when compared with similarly stimulated human aortic macrovascular endothelial cells. CONCLUSIONS: These data indicate that LMVEC express less iNOS and produce less NO than AEC. This lower expression and activity of iNOS in LMVEC may be linked to increased expression of ICAM-1. Because ICAM-1 has been shown to be essential for tight PMN adherence, these data suggest that relatively low iNOS expression in LMVEC may contribute to a propensity for the lung to be injured by activated PMNs.     

Hypertonic resuscitation of hemorrhagic shock upregulates the anti-inflammatory response by alveolar macrophages

BACKGROUND: Resuscitated hemorrhagic shock predisposes patients to the development of acute respiratory distress syndrome (ARDS). Hypertonic saline (HTS) has been shown to inhibit immune cell activation in response to lipopolysaccharide (LPS) in vitro and to reduce lung damage when used for resuscitation of hemorrhagic shock in vivo. We hypothesize that HTS resuscitation of hemorrhagic shock may exert this anti-inflammatory effect by modulating alveolar macrophage function leading to an altered balance between the proinflammatory and the counter-inflammatory response. METHODS: A 2-hit rat model of shock resuscitation was used. Alveolar macrophages were harvested by bronchoalveolar lavage (BAL), and tumor necrosis factor (TNF)-alpha and interleukin (IL)-10 were quantified in the cell culture supernatants by enzyme-linked immunosorbent assay (ELISA). Alternatively, 1 hour after resuscitation, animals received endotracheal LPS followed by endotracheal anti-IL-10 neutralizing antibody. Lung injury was determined by measuring BAL neutrophil counts 4 hours after LPS in vivo administration. RESULTS: Systemic administration of HTS significantly modulates the responsiveness of alveolar macrophages. Specifically, HTS resuscitation inhibited LPS-induced TNF-alpha production while enhancing IL-10 release in response to LPS administered ex vivo and in vivo. Anti-IL-10 antibody in vivo partially reversed the lung protective effect of HTS resuscitation. CONCLUSIONS: HTS resuscitation exerts an immunomodulatory effect on alveolar macrophages by shifting the balance of pro- and counter-inflammatory cytokine production in favor of an anti-inflammatory response. The in vivo data suggest a causal role for HTS-induced augmented IL-10 as protective. These findings suggest a novel mechanism for the in vivo salutary effect of HTS resuscitation on lung injury after resuscitated hemorrhagic shock.     

Mesenteric lymph is responsible for post-hemorrhagic shock systemic neutrophil priming.

BACKGROUND: Hemorrhagic shock-induced splanchnic hypoperfusion has been implicated as a priming event in the two event model of multiple organ failure (MOF). We have previously shown that early postinjury neutrophil (PMN) priming identifies the injured patient at risk for MOF. Recent in vitro studies have demonstrated that postshock mesenteric lymph primes isolated human neutrophils. We hypothesize that lymphatic diversion before hemorrhagic shock abrogates systemic PMN priming and subsequent lung injury. METHODS: Sprague-Dawley rats (n >or= 5 per group) underwent hemorrhagic shock (MAP 40 mm Hg x 30 min) and resuscitation (shed blood + 2x crystalloid) with and without mesenteric lymphatic duct diversion. Sham animals underwent anesthesia and laparotomy. Whole blood was taken 2 hours after resuscitation, heparinized, and incubated for 5 min at 37 degrees C. Surface expression of CD11b (a marker for PMN priming) was determined by flow-cytometry compared with isotype controls. In addition, lung myeloperoxidase (MPO) was measured for PMN sequestration, and Evans blue lung leak was assessed in the bronchoalveolar lavage fluid in sham, and shock +/- lymph diversion animals. RESULTS: Hemorrhagic shock resulted in increased surface expression of PMN CD11b relative to sham (23.8 +/- 6.7 vs. 9.9 +/- 0.6). Mesenteric lymphatic diversion before hemorrhagic shock abrogated this effect (8.0 +/- 2.6). Lung PMN accumulation, as assessed by MPO, was greater in the lungs of nondiverted (113 +/- 14 MPO/mg lung) versus sham (55 +/- 4 MPO/mg lung, p < 0.05); lymph diversion reduced lung PMNs to control levels (71 +/- 6.5 MPO/mg lung, p < 0.05). Evans blue lung leak was 1.6 times sham in the hemorrhagic shock group; this was returned to sham levels after lymph diversion (p < 0.05). CONCLUSION: Post-hemorrhagic shock mesenteric lymph primes circulating PMNs, promotes lung PMN accumulation, and provokes acute lung injury. Lymphatic diversion abrogates these pathologic events. These observations further implicate the central role of mesenteric lymph in hemorrhagic shock-induced lung injury. Characterizing the PMN priming agents could provide insight into the pathogenesis of postinjury MOF and ultimately new therapeutic strategies.     

烟雾吸入伤血清对中性粒细胞粘附及迁移作用的体外研究

目的 通过鼠烟雾吸入伤血清体外刺激培养内皮细胞和中性粒细胞（ＰＭＮ），了解ＰＭＮ粘会与迁移变化，以及抗ＣＤ１１ａ，抗ＣＤ１１ｂ和抗ＩＣＡＭ－１对ＰＭＮ粘附与迁移的影响，探讨粘附因子在烟雾吸入性损伤中的作用。方法 在体外实验中用荧光标记ＰＭＮ，测定ＰＭＮ与烟雾吸入性损伤血清刺激的内皮细胞的粘附率，在５μｍ滤膜上培养仙皮细胞测定ＰＭＮ迁移量，并采用抗体阻断技术，测定了粘附因子ＣＤ１１ａ，ＣＤ１１ｂ和Ｉ     

Effects of lung preservation solutions on PMN activation in vitro

Polymorphonuclear leukocyte (PMN) activation and PMN-endothelial cell interactions may cause graft failure due to ischemia-reperfusion injury after lung transplantation. We investigated the effects of Euro-Collins solution (EC), low-potassium dextran solution (LPD), and EC plus pentoxifylline (EC-PTXF) on adhesion molecule (CD11b/CD18 and L-selectin) expression, chemotaxis, and oxidative burst of PMN. PMN from healthy human volunteers were incubated with EC, LPD, and EC-PTXF, and, in controls, without preservation solution. LPD exerted a suppressive effect on PMN chemotaxis as compared to EC (P < 0.05), but had no attenuating effect on the increase of CD11b/CD18, the shedding of L-selectin, and intracellular oxidant generation. EC-PTXF attenuated the expression of CD11b/CD18 and the oxidative burst as compared to EC alone (P < 0.05). These effects of LPD and PTXF on PMN function may contribute to successful organ preservation in transplantation. Received 22 June 98 Received after revision: 30 December 1998 Accepted: 19 January 99     

Posthemorrhagic shock mesenteric lymph primes circulating neutrophils and provokes lung injury.

Mesenteric lymph has recently been invoked as an avenue for gut-derived factors that may result in distant organ injury following hemorrhagic shock. We demonstrate that posthemorrhagic shock mesenteric lymph primes neutrophils (PMNs) and causes lung injury. Methods. Mesenteric lymph was collected from Sprague-Dawley rats from their mesenteric lymph duct prior to, during, and following hemorrhagic shock (MAP 40 for 90 min). The rats were then resuscitated with shed blood plus lactated Ringers (2X shed blood) over 3 h. Lung leak was assessed by transudation of Evan's blue dye into the alveolus as measured by bronchoalveolar lavage. Isolated human PMNs were incubated with 1 and 10% lymph; priming was measured by the fMLP (1 microM)-stimulated production of superoxide and surface expression of CD11b determined by flow cytometry. Results. Mesenteric lymph flow increased significantly during resuscitation: preshock 144.4 microl/h, shock 44.5 microl/h, resuscitation 566.6 microl/h. Furthermore, diversion of this lymph abrogated lung injury as compared to rats without lymph diversion. Finally, mesenteric lymph from postshock animals primed PMNs for superoxide production (nearly three times control cells) as well as increased surface expression of CD11b (2-fold over control). Conclusion. Mesenteric lymph primes PMNs and causes lung injury following hemorrhagic shock. Mesenteric lymph provides a conduit for proinflammatory mediators that may participate in the pathogenesis of MOF.     

Resuscitation-induced pulmonary apoptosis and intracellular adhesion molecule-1 expression in rats are attenuated by the use of Ketone Ringer's solution

BACKGROUND: Resuscitation with Lactated Ringer's solution after hemorrhagic shock in rats has been shown to cause early cellular injury in the lung. We hypothesized that the use of energy substrates, such as ketone bodies, in the resuscitation fluids would protect against this injury. As markers of cellular injury we measured the induction of apoptotic cell death and the expression of Intracellular Adhesion Molecule-1 (ICAM-1). STUDY DESIGN: Male Sprague Dawley rats (n = 35) under inhaled isoflurane anesthesia had placement of femoral arterial and venous catheters. A three-stage hemorrhage model was used for this experiment. There was an initial hemorrhage of 27 mL/kg for 10 minutes. During the next 75 minutes another 8 mL/kg of blood was withdrawn at a steady rate. The resuscitation fluids were then infused for 45 minutes during which the third continuous hemorrhage of 8 mL/kg was performed. The animals were randomized to five groups: 1) sham hemorrhage (n = 6); 2) sham resuscitation (n = 7); 3) Lactated Ringer's resuscitation, three times the volume of shed blood (n = 8); 4) Ketone Ringer's (containing 28 mEq/L of beta-hydroxybutyrate) resuscitation, three times the volume of shed blood (n = 7); and 5) plasma resuscitation, volume equal to shed blood (n = 7). The animals were sacrificed 1 hour after resuscitation and lungs were harvested. Western blot technique was used for the determination of proapoptotic protein (bax), antiapoptotic protein (bcl-2), apoptotic fragments of poly ADP-ribose polymerase, and ICAM-1. Sections of lung were also subjected to immunostaining using antibodies to bax and ICAM-1 proteins (reported as number of positive cells/mm2). RESULTS: Lactated Ringer's resuscitation caused a significant increase in pulmonary apoptosis and ICAM-1 expression compared with the sham hemorrhage group. Animals resuscitated with Ketone Ringer's solution and plasma did not show this injury pattern. CONCLUSIONS: Substitution of lactate with ketone bodies in the resuscitation fluid attenuates the expression of cellular injury markers in the lung.     

Hypertonic saline resuscitation abrogates neutrophil priming by mesenteric lymph

OBJECTIVE: Neutrophil (PMN) priming after hemorrhagic shock is predictive of the subsequent development of multiple organ failure, but the mechanism remains unknown. Recently, we and others have demonstrated that mesenteric lymph from shock animals resuscitated with lactated Ringer's solution (LR) is not only a potent PMN priming agent but also causes lung injury. Work by others has shown that resuscitation with hypertonic saline (HTS) protects animals from lung injury after hemorrhagic shock. Therefore, we hypothesize that resuscitation with HTS will abolish PMN priming by postshock mesenteric lymph. METHODS: After mesenteric lymph duct catheterization, male rats underwent hemorrhagic shock (mean arterial pressure of 40 mm Hg for 90 minutes) and resuscitation with shed blood plus either LR (2x volume of shed blood) or 4 mL/kg of 7% HTS (isonatremic). Priming for superoxide by PMN was measured after fMLP (1 microM) activation. RESULTS: Shock significantly decreased mesenteric lymph flow from preshock levels in both groups. LR resuscitation produced significantly more mesenteric lymph than HTS resuscitation. Mesenteric lymph from LR animals primed PMN for superoxide production, whereas, HTS eliminated this priming. CONCLUSION: HTS not only decreases postshock mesenteric lymph production, it eliminates PMN priming by mesenteric lymph, suggesting a mechanism for the beneficial effects of HTS resuscitation.     

Granulocyte colony-stimulating factor (G-CSF) production in hemorrhagic shock requires both the ischemic and resuscitation phase

Granulocyte colony-stimulating factor (G-CSF) is the cytokine that is critical for polymorphonuclear neutrophilic granulocyte (PMN) production as well as being a potent agonist of PMN activation. We have recently reported that in the lung and the liver of rats resuscitated after hemorrhagic shock (HS) G-CSF mRNA expression is induced. It is not known if both phases of HS, the ischemic and the reperfusion phase, are required for G-CSF mRNA induction. The present study was designed to test the hypothesis that the upregulation of G-CSF mRNA expression is the consequence of HS followed by resuscitation and that ischennia alone is insufficient to induce G-CSF mRNA expression in the affected organs. Male Sprague-Dawley rats were subjected to resuscitated and unresuscitated shock protocols of varying severity. Control animals were subjected to anesthesia and all surgical preparations except for hemorrhage. Lungs and livers were isolated and their RNA extracted. Using semiquantitative reverse trans criptase-polymerase chain reaction (RT-PCR), we demonstrated that G-CSF mRNA was induced in the lung and liver of shock animals above the level observed in control animals. Upregulation of G-CSF mRNA relative to controls occurred only in animals undergoing resuscitated HS and not in ones subjected to unresuscitated HS. These results indicate that G-CSF production specific for the hemorrhage component of shock is dependent on resuscitation. As a consequence, the production of this cytokine may be decreased through modifications in the resuscitation protocols.