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In this study, we examined whether IL-18 plays a role in lung inflammation following alcohol (EtOH) and burn injury. Male rats (~250 g) were gavaged with EtOH to achieve a blood EtOH level of ~100 mg/dl before burn or sham injury (~12.5% total body surface area). Immediately after injury, rats were treated with vehicle, caspase-1 inhibitor AC-YVAD-CHO to block IL-18 production or with IL-18 neutralizing anti-IL-18 antibodies. In another group, rats were treated with anti-neutrophil antiserum ~16 h before injury to deplete neutrophils. On day 1 after injury, lung tissue IL-18, neutrophil chemokines (CINC-1/CINC-3), ICAM-1, neutrophil infiltration, MPO activity, and water content (i.e., edema) were significantly increased in rats receiving a combined insult of EtOH and burn injury compared with rats receiving either EtOH intoxication or burn injury alone. Treatment of rats with caspase-1 inhibitor prevented the increase in lung tissue lL-18, CINC-1, CINC-3, ICAM-1, MPO activity, and edema following EtOH and burn injury. The increase in lung IL-18, MPO, and edema was also prevented in rats treated with anti-IL-18 antibodies. Furthermore, administration of anti-neutrophil antiserum also attenuated the increase in lung MPO activity and edema, but did not prevent the increase in IL-18 levels following EtOH and burn injury. These findings suggest that acute EtOH intoxication before burn injury upregulates IL-18, which in turn contributes to increased neutrophil infiltration. Furthermore, the presence of neutrophils appears to be critical for IL-18-meditaed increased lung tissue edema following a combined insult of EtOH and burn injury. [ABSTRACT FROM AUTHOR]

Toll-like receptor 4 (TLR4) mediates mitochondrial DNA (mtDNA) damage and biogenic responses. Mitochondrial transcription factor A (Tfam) is an essential regulator for mtDNA transcription and ATP production. Increased ATP levels were associated with normalization of immune function following trauma-hemorrhage. Moreover, administration of 17β-estradiol following trauma-hemorrhage upregulates cardiac Tfam and ATP levels. We therefore hypothesized that the salutary effect of 17β-estradiol on Kupffer cell function following trauma-hemorrhage is mediated via negative regulation of TLR4, which downregulates iNOS, upregulates Tfam and mtDNA-encoded gene cytochrome c oxidase I (mtCOI), and consequently increases cellular ATP levels. Male C3H/HeN, C3H/HeOuJ (intact TLR4), and C3H/HeJ (TLR4 mutant) mice were subjected to trauma-hemorrhage (mean BP 35 ± 5 mmHg ∼90 min, then resuscitation) or sham operation. At the beginning of resuscitation, mice received 17β-estradiol (25 µg/25 g) or vehicle intravenously and were sacrificed 2 h thereafter. Kupffer cell TLR4, iNOS, IL-6 and TNF-α production capacities were increased, and ATP, Tfam, and mtCOI levels were decreased following trauma-hemorrhage. Administration of 17β-estradiol following trauma-hemorrhage prevented the increase in Kupffer cell TLR4, iNOS, and cytokine production. This was accompanied by normalized ATP, Tfam, and mtCOI levels. Furthermore, the decreased Kupffer cell ATP and mtCOI levels were not observed in TLR4 mutant mice following trauma-hemorrhage. Taken together, these findings suggest that downregulation of TLR4-dependent ATP production is critical to 17β-estradiol-mediated immunoprotection in Kupffer cells following trauma-hemorrhage. J. Cell. Physiol. 211: 364–370, 2007. © 2007 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Leukocyte infiltration, mediated by chemokines, is a key step in the development of organ dysfunction. Lung and liver neutrophil infiltration following trauma- hemorrhage is associated with upregulation of monocyte chemoattractant protein-1 (MCP-1). Because MCP-1 is not a major attractant for neutrophils, we hypothesized that MCP-1 influences neutrophil infiltration via regulation of keratinocyte-derived chemokines (KC). To study this, male C3H/HeN mice were pretreated with MCP-1 anti-serum or control serum and subjected to trauma-hemorrhage or sham operation. Animals were killed 4 h after resuscitation. One group of trauma-hemorrhage mice receiving MCP-1 antiserum was also treated with murine KC during resuscitation. Plasma levels and tissue content of MCP-1 and KC were determined by cytometric bead arrays. Immunohistochemistry was performed to determine neutrophil infiltration; organ damage was assessed by edema formation. Treatment with MCP-1 antiserum significantly decreased systemic, lung, and liver levels of MCP-1 and KC following trauma-hemorrhage. This decrease in MCP-1 levels was associated with decreased neutrophil infiltration and edema formation in lung and liver following trauma-hemorrhage. Restitution of KC in mice treated with MCP-1 antiserum restored tissue neutrophil infiltration and edema. These results lead us to conclude that increased levels of MCP-1 cause neutrophil accumulation and distant organ damage by regulating KC production during the postinjury inflammatory response. [ABSTRACT FROM AUTHOR]

Severe injury deranges immune function and increases the risk of sepsis and multiple organ failure. Kupffer cells play a major role in mediating posttraumatic immune responses, in part via different Toll-like receptors (TLR). Although mitogen-activated protein kinases (MAPK) are key elements in the TLR signaling pathway, it remains unclear whether the activation of different MAPK are TLR specific. Male C3H/HeN mice underwent midline laparotomy (i.e., soft tissue injury), hemorrhagic shock (MAP ∼35 mm Hg for 90 min), and resuscitation. Kupffer cells were isolated 2 h thereafter, lysed and immunoblotted with antibodies to p38, ERK1/2, or JNK proteins. In addition, cells were preincubated with specific inhibitors of p38, ERK1/2, or JNK MAPK followed by stimulation with the TLR2 agonist, zymosan; the TLR4 agonist, LPS; or the TLR9 agonist, CpG DNA. Cytokine (TNF-α, interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and KC) production was determined by cytometric bead array after 24 h in culture. MAPK activity as well as TNF-α, MCP-1, and KC production by Kupffer cells were significantly increased following trauma-hemorrhage. TLR4 activation by LPS stimulation increased the levels of all measured cytokines. CpG-stimulated TLR9 signaling increased TNF-α and IL-6 levels; however, it had no effect on chemokine production. Selective MAPK inhibition demonstrated that chemokine production was mediated via p38 and JNK MAPK activation in TLR2, -4, and -9 signaling. In contrast, TNF-α and IL-6 production was differentially regulated by MAPK depending on the TLR pathway stimulated. Thus, Kupffer cell TLR signaling employs different MAPK pathways in eliciting cytokine and chemokine responses following trauma-hemorrhage. J. Cell. Physiol. 210: 667–675, 2007. © 2006 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Although endothelin-1 (ET-1) induces vasoconstriction, it remains unknown whether 17β-estradiol (E2) treatment following trauma-hemorrhage alters these ET-1-induced vasoconstrictive effects. In addition, the role of the specific estrogen receptor (ER) subtypes (ER-α and ER-β) and the endothelium-localized downstream mechanisms of actions of E2 remain unclear. We hypothesized that E2 attenuates increased ET-1-induced vasoconstriction following trauma-hemorrhage via an ER-S-mediated pathway. To study this, aortic rings were isolated from male Sprague-Dawley rats following trauma-hemorrhage with or without E2 treatment, and alterations in tension were determined in vitro. Dose-response curves to ET-1 were determined, and the vasoactive properties of E2, propylpyrazole triol (PPT, ER-α agonist), and diarylpropionitrile (DPN, ER-β agonist) were determined. The results showed that trauma-hemorrhage significantly increased ET-1-induced vasoconstriction; however, administration of E2 normalized ET-1-induced vasoconstriction in trauma-hemorrhage vessels to the sham-operated control level. The ER-~3 agonist DPN counteracted ET-1-induced vasoconstriction, whereas the ER-α agonist PPT was ineffective. Moreover, the vasorelaxing effects of E2 were not observed in endothelium-denuded aortic rings or by pretreatment of the rings with a nitric oxide (NO) synthase inhibitor. Cyclooxygenase inhibition with indomethacin had no effect on the action of E2. Thus, E2 administration attenuates ET-1-induced vasoconstriction following trauma-hemorrhage via an ER-β-mediated pathway that is dependent on endothelium-derived NO synthesis. [ABSTRACT FROM AUTHOR]

Traumatic and/or surgical injury as well as hemorrhage induces profound suppression of cellular immunity. Although local anesthetics have been shown to impair immune responses, it remains unclear whether lidocaine affects lymphocyte functions following trauma-hemorrhage (T-H). We hypothesized that lidocaine will potentiate the suppression of lymphocyte functions after T-H. To test this, we randomly assigned male C3H/HeN (6-8 wk) mice to sham operation or T-H. T-H was induced by midline laparotomy and ∼90 min of hemorrhagic shock (blood pressure 35 mmHg), followed by fluid resuscitation (4X shed blood volume in the form of Ringer lactate). Two hours later, the mice were killed and splenocytes and bone marrow cells were isolated. The effects of lidocaine on concanavalin A-stimulated splenocyte proliferation and cytokine production in both sham-operated and T-H mice were assessed. The effects of lidocaine on LPS-stimulated bone marrow cell proliferation and cytokine production were also assessed. The results indicate that T-H suppresses cell proliferation, Th1 cytokine production, and MAPK activation in splenocytes. In contrast, cell proliferation, cytokine production, and MAPK activation in bone marrow cells were significantly higher 2 h after T-H compared with shams. Lidocaine depressed immune responses in splenocytes; however, it had no effect in bone marrow cells in either sham or T-H mice. The enhanced immunosuppressive effects of lidocaine could contribute to the host's enhanced susceptibility to infection following T-H. [ABSTRACT FROM AUTHOR]

Tissue hypoxia is a common sequel of trauma-hemorrhage but can occur even without blood loss under hypoxic conditions. Although hypoxia is known to upregulate Kupffer cells (KC) to release cytokines, the precise mechanism of release remains unknown. We hypothesized that Src family kinases play a role in mediating KC mitogen-activated protein kinase (MAPK) signaling and their cytokine production after hypoxia. Male C3H/HeN mice received either Src inhibitor PPl (1.5 mg/kg body wt) or vehicle 1 h before hypoxia. KCs were isolated 1 h after hypoxia, lysed, and immunoblotted with antibodies to Src, p38, ERK1/2, or JNK proteins. In addition, KCs were cultured to measure interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) production. Hypoxia produced a significant increase in KC Src and MAPK (p38, ERK, JNK) activity compared with normoxic controls. This was associated with an increase in IL-6 and MCP-1 production. Treatment with PPl abolished the increase in KC Src activation as well as p38 activity. However, PPl did not prevent the increase in KC ERK1/2 or JNK phosphorylation. Furthermore, administration of PPl prevented the hypoxia- induced increase in IL-6 but not MCP-l release by KC. Additional in vitro results suggest that p38 but not ERKI/2 or JNK are critical for KC IL-6 production. In contrast, the production of MCP- I by KC was found to be independent of MAPK. Thus hypoxia increases KC lL-6 production by p38 MAPK activation via Src-dependent pathway. Src kinases may therefore be a novel therapeutic target for preventing immune dysfunction following low-flow conditions in trauma patients. [ABSTRACT FROM AUTHOR]

Although androstenediol (adiol or 5-androstene-3β,17β-diol), a metabolite of dehydroepiandrosterone (DHEA), has protective effects following trauma-hemorrhage (T-H), it remains unknown whether administration of adiol has any salutary effects on the inflammatory response and outcome following a combined insult of T-H and sepsis. Male rats underwent T-H shock [mean arterial pressure (MAP) 40 mmHg for 90 mini followed by resuscitation. Adiol (1 mg/kg body wt) or vehicle was administered at the end of resuscitation. Sepsis was induced by cecal ligation and puncture (CLP) at 20 h after T-H or sham operation. Five hours after CLP, plasma and tissue samples were analyzed for cytokines (IL-6 and IL-10), MPO, neutrophil chemotactic factor (CINC-3), and liver injury (alanine aminotransferase and lactate dehydrogenase). In another group of rats, the gangrenous cecum was removed at 10 h after CLP, the cavity was irrigated with warm saline and closed in layers, and mortality was recorded over 10 days. T-H followed by CLP produced a significant elevation in plasma IL-6 and IL-10 levels, enhanced neutrophil cell activation, and resulted in liver injury. Adiol administration prevented the increase in cytokine production, neutrophil cell activation, and attenuated liver injury. Moreover, rats subjected to the combined insult, receiving vehicle or adiol, had a 50% and 6% mortality, respectively. Since adiol administration suppresses proinflammatory cytokines, reduces liver damage, and decreases mortality after the combined insult of T-H and sepsis, this agent appears to be a novel adjunct to fluid resuscitation for decreasing T-H-induced septic complications and mortality. [ABSTRACT FROM AUTHOR]

Abstract: Background: Immune and infectious complications are associated with burn injury. Opiate analgesics also can induce similar complications, however, their impact on postburn infectious complications is unknown. Methods: A retrospective survey of records from 1997 to 2002 from an academic burn center was conducted. Information on all opiate analgesic use was obtained and expressed as opiate equivalents (OEs). Total OEs were summed for each patient and then compared between cases and controls. Results: Patients who developed infections were more likely to be in the high OE group. This association was modified by burn severity. Patients with small burns and infection were more likely to be in the high OE group, whereas patients with moderate to large burns and infections were not associated significantly with opiate use. Conclusions: The results of this preliminary study suggest that opiate analgesics can contribute to the development of postburn infectious complications when the burn injury is of a less severe nature. [Copyright &y& Elsevier]

Although 17β-estradiol (E2) administration after trauma-hemorrhage attenuates lung injury in male rodents, it is not known whether the salutary effects are mediated via estrogen receptor (ER)-α or ER-β. We hypothesized that the salutary effects of E2 lung are mediated via ER-β. Male Sprague­Dawley rats underwent trauma-hemorrhage (mean blood pressure 40 mmHg for 90 mm, then resuscitation). E2 (50 μg/kg), ER-α agonist propyl pyrazole triol (PPT; 5 μg/kg), ER-β agonist diarylpropiolnitrile (DPN; 5 μg/kg), or vehicle (10% DMSO) was injected subcutaneously during resuscitation. At 24 h after trauma-hemorrhage or sham operation, bronchoalveolar fluid (BALF) was collected for protein concentration, LDH activity, and nitrate/nitrite and IL-6 levels. Moreover, lung tissue was used for inducible nitric oxide synthase (iNOS) mRNA/protein expression, nitrate/nitrite and IL-6 levels, and wet/dry weight ratio (n = 6 rats/group). One-way ANOVA and Tukey's test were used for statistical analysis. The results indicated that E2 downregulated lung iNOS expression after trauma-hemorrhage. Protein concentration, LDH activity, and nitrate/nitrite and IL-6 levels in BALF and nitrate/nitrite and IL-6 levels in the lung increased significantly after trauma-hemorrhage; however, administration of DPN but not PPT significantly improved all parameters. Moreover, DPN treatment attenuated trauma-hemorrhage-mediated increase in iNOS mRNA/protein expression in the lung. In contrast, no significant change in the above parameters was observed with PPT. Thus the salutary effects of E2 on attenuation of lung injury are mediated via ER-β, and ER-β-induced downregulation of iNOS likely plays a significant role in the DPN-mediated lung protection after trauma-hemorrhage. [ABSTRACT FROM AUTHOR]

Although studies indicate that 17β-estradiol administration after trauma-hemorrhage (T-H) improves cardiac and hepatic functions, the underlying mechanisms remain unclear. Because the induction of heat shock proteins (HSPs) can protect cardiac and hepatic functions, we hypothesized that these proteins contribute to the salutary effects of estradiol after T-H. To test this hypothesis, male Sprague-Dawley rats (∼300 g) underwent laparotomy and hemorrhagic shock (35–40 mmHg for ∼90 min) followed by resuscitation with four times the shed blood volume in the form of Ringer lactate. 17β-estradiol (1 mg/kg body wt) was administered at the end of the resuscitation. Five hours after T-H and resuscitation there was a significant decrease in cardiac output, positive and negative maximal rate of left ventricular pressure. Liver function as determined by bile production and indocyanine green clearance was also compromised after T-H and resuscitation. This was accompanied by an increase in plasma alanine aminotransferase (ALT) levels and liver perfusate lactic dehydrogenase levels. Furthermore, circulating levels of TNF-α, IL-6, and IL-10 were also increased. In addition to decreased cardiac and hepatic function, there was an increase in cardiac HSP32 expression and a reduction in HSP60 expression after T-H. In the liver, HSP32 and HSP70 were increased after T-H. There was no change in heart HSP70 and liver HSP60 after T-H and resuscitation. Estradiol administration at the end of T-H and resuscitation increased heart/liver HSPs expression, ameliorated the impairment of heart/liver functions, and significantly prevented the increase in plasma levels of ALT, TNF-α, and IL-6. The ability of estradiol to induce HSPs expression in the heart and the liver suggests that HSPs, in part, mediate the salutary effects of 17β-estradiol on organ functions after T-H. [ABSTRACT FROM AUTHOR]

Although previous studies have shown that flutamide improves cardiovascular function after trauma-hemorrhage, the mechanisms responsible for the salutary effect remain unknown. We hypothesized that flutamide mediates its beneficial effects via an estrogen-dependent pathway through upreguIation of peroxisome proliferator-activated receptor-γ coactivator 1 (PGC-1). PGC-1, a key regulator of cardiac mitochondrial ATP production, induces mitochondrial DNA (mtDNA)-encoded genes such as cytochrome-c oxidase (COX) subunit I, II, and III (COX I, COX II, and COX III), which regulates mitochondrial oxidative phosphorylation. To test this hypothesis, male rats underwent trauma-hemorrhage (mean arterial pressure of 35-40 mmHg for -90 mm) followed by resuscitation. At the onset of resuscitation, rats received vehicle, flutamide (25 mg/kg body wt), flutamide in combination with estrogen receptor (ER) antagonist ICI-182,780 (3 mg/kg body wt), or ICE-182,780 alone. Flutamide administration after trauma-hemorrhage restored the depressed cardiac function and increased cardiac testosterone, estrogen levels, and aromatase activity. These increases were accompanied by normalized cardiac ER-α and ER-β protein levels, PGC-1, and COX I mRNA expression, mitochondrial COX activity, and ATP contents. However, cardiac dihydrotestosterone, 5α-reductase II, androgen receptor protein levels, and mtDNA- encoded genes COX II and COX III were unaffected by flutamide treatment. The flutamide-mediated restoration of cardiac function, the increases in aromatase activity and estrogen levels, ER-α, ER-β, PGC-1I, COX 1, COX activity, and ATP contents were, however, abolished when ER antagonist ICI- 182,780 was administrated along with flutamide. These findings suggest that the salutary effect of flutamide on cardiac function after trauma-hemorrhage is mediated via an estrogen-dependent pathway through upregulation of PGC-1. [ABSTRACT FROM AUTHOR]

A growing body of evidence indicates that heme degradation products may counteract the deleterious consequences of hypoxia and/or ischemia-reperfusion injury. Because heme oxygenase (HO)-1 induction after adverse circulatory conditions is known to be protective, and because females in the proestrus cycle (with high estrogen) have better hepatic function and less hepatic damage than males after trauma-hemorrhage, we hypothesized that estrogen administration in males after trauma-hemorrhage will upregulate HO activity and protect the organs against dysfunction and injury. To test this hypothesis, male Sprague-Dawley rats under went 5-cm laparotomy and hemorrhagic shock (35–40 mmHg for 93 ± 2 rain), followed by resuscitation with four times the shed blood volume in the form of Ringer lactate. 17Β-Estradiol and/or the specific HO enzyme inhibitor chromium mesoporphyrin (CrMP) were administered at the end of resuscitation, and the animals were killed 24 h thereafter. Trauma-hemorrhage reduced cardiac output, myocardial contractility, and serum albumin levels. Portal pressure and serum alanine aminotransferase levels were markedly increased under those conditions. These parameters were significantly improved in the 17Β-estradiol-treated rats. Estradiol treatment also induced increased HO-1 mRNA expression, HO-1 protein levels, and HO enzymatic activity in cardiac and hepatic tissue compared with vehicle treated trauma-hemorrhage rats. Administration of the HO inhibitor CrMP prevented the estradiol-induced attenuation of shock-induced organ dysfunction and damage. Thus the salutary effects of estradiol administration on organ function after trauma-hemorrhage are mediated in part via upregulation of HO-1 expression and activity. [ABSTRACT FROM AUTHOR]

Recent studies have shown that administration of dehydroepiandrosterone (DHEA) after trauma-hemorrhage (T-H) improves cardiovascular and hepatic function in male animals. Although androstenediol, one of the DHEA metabolites, has been recently reported to produce salutary effects on cardiac function and splanchnic perfusion after T-H, it remains unknown whether androstenediol per se has any salutary effects on hepatic function under those conditions. To study this, male Sprague-Dawley rats underwent laparotomy and ∼90 min of hemorrhagic shock (35-40 mmHg), followed by resuscitation with four times the shed blood volume in the form of Ringer lactate. Androstenediol (1 mg/kg body wt iv) was administered at the end of resuscitation, and the animals were killed 24 h later. T-H significantly reduced portal blood flow, bile production, and serum albumin levels. Portal pressure, serum alanine aminotransferase, hepatic nitrate/nitrite, inducible nitric oxide synthase (iNOS), and endothelin-1 markedly increased after T-H. The alterations in these parameters induced by T-H were significantly attenuated in rats treated with androstenediol. Endothelial NOS (eNOS) expression, which was not different between T-H and sham, was found to be significantly elevated in T-H androstenediol-treated rats. These data suggest that improvement in hepatic perfusion by androstenediol after T-H is likely due to a decrease in endothelin-1 and induction of eNOS. Moreover, the decrease in hepatic damage after androstenediol administration is likely related to liver iNOS downregulation. Thus androstenediol appears to be a novel and useful adjunct for restoring hepatic function in male animals after adverse circulatory conditions. [ABSTRACT FROM AUTHOR]

IL-6 and TNF-α production by Kupffer cells is markedly stimulated following traumahemorrhage (T-H). Because IL-10 is an anti-inflammatory cytokine, the aim of this study was to determine whether IL-10 regulates Kupffer cell proinflammatory cytokine release following T-H. To study this, we subjected adult male Sprague-Dawley rats to sham operation or T-H. The procedure involved a 5-cm midline laparotomy and ∼90 min of hemorrhagic shock (35 mmHg), followed by resuscitation with four times the shed blood volume in the form of Ringer's lactate. At 2 h after the end of resuscitation, livers were perfused in vitro and perfusate was collected. In separate studies, Kupffer cells were isolated and incubated with different concentrations of anti-IL-10 MAb. IgG was used as control. After 16 h of incubation, IL-6 and TNFα levels were measured by ELISA. Plasma IL-10 levels increased significantly following T-H. IL-10 levels in the perfusate and IL-10 production by cultured Kupffer cells were also significantly higher in the T-H group. When Kupffer cells were incubated with 10 μg/ml of anti-IL-10 MAb, IL-6 and TNF-α production were significantly increased in both sham and T-H groups compared with those not treated with anti-IL-10 MAb. However, these changes were not observed when the cells were incubated with irrelevant (control) IgG. These results indicate that IL-10 production by Kupffer cells early after T-H may play a pivotal role in attenuating the proinflammatory cytokine environment, possibly in an autocrine/paracrine manner. [ABSTRACT FROM AUTHOR]

Pro-inflammatory cytokine release after shock is central in the development of subsequent multiple organ dysfunction syndrome. Some studies suggest that interleukin-10 (IL-10) is an immunosuppressive mediator after injury or sepsis, while others suggest that IL-10 is an important regulator of the pro-inflammatory response. We hypothesized that in a model of trauma and hemorrhagic shock (TH), IL-10 regulates pro-inflammatory cytokine activity via an autocrine effect on cytokine mRNA transcription in Kupffer cells early after TH. To study this, male C3H/HeN mice were sham-operated or subjected to TH. Plasma levels of TNF-α, IL-6 and PGE2 were elevated following TH. A sharp peak in IL-10 levels was observed at 2 h after the insult. Kupffer cell (KC) depletion prior to TH reduced plasma IL-6, IL-10 and TNF-α levels, whereas treatment with anti-IL-10 after TH increased IL-6 and TNF-α levels. Kupffer cell mRNA expression for IL-6, IL-10 and TNF-α was elevated in the TH group and further increased by anti-IL-10 treatment. These findings indicate that KC-dependent IL-10 regulates the early systemic inflammatory response after TH. Thus, while IL-10 is an important mediator of immunosuppression following traumatic injury, it also is beneficial with regard to its ability to counter-regulate the early inflammatory response under such conditions. [Copyright &y& Elsevier]

Studies have shown that 17β-estradiol has salutary effects on immune functions after trauma–hemorrhage (TH). It remains unknown, however, whether 17β-estradiol has a similar effect in a double-hit model of TH and subsequent sepsis. It is also unknown if under those conditions the circulating immune cells accurately represent immunological responses occurring in fixed tissues, such as the spleen. To study this, pre-castrated mice were hormonally treated and then subjected to soft-tissue trauma (i.e. midline laporatomy), hemorrhagic shock (MAP 35±5 mmHg for 90 min followed by resuscitation) and 24 h later sepsis was induced by cecal ligation and puncture (CLP). Splenic macrophages (SMφ) and peripheral blood mononuclear cells (PBMC) were isolated and cultured with LPS. 5α-Dihydrotestosterone-treated mice showed a depressed pro-inflammatory cytokine production after TH-sepsis in both SMφ and PBMC. In contrast, the 17β-estradiol treated groups showed suppressed pro-inflammatory cytokine production in the PBMC population under those conditions. In summary, 17β-estradiol was able to prevent immune dysfunction after TH and subsequent sepsis. However, the beneficial effects of 17β-estradiol were limited to tissue-fixed Mφ, suggesting compartmentalization of the response. Thus, events occurring in the tissue-fixed cells are not necessarily reflected in the circulating PBMC population. [Copyright &y& Elsevier]

Thromboxane A[sub 2] (TXA[sub 2]) and endothelin-1 (ET-1) have been proposed as the important vasoconstrictors that increase portal venous resistance in paracrine or autocrine fashion. We hypothesized that the hepatic damage following trauma-hemorrhage (T-H) is induced by the impaired hepatic circulation due to the increased production of vasoconstrictors such as ET-1 and TXA[sub 2] by the liver. To test this, male Sprague-Dawley rats (n = 6/group) were subjected to trauma (i.e., midline laparotomy) and hemorrhage (35-40 mmHg for 90 min followed by fluid resuscitation) or sham operation. At 2 or 5 h after the end of resuscitation, the liver was isolated and perfused and portal inflow pressure, bile flow, and release of ET-1 and thromboxane B[sub 2] (TXB[sub 2]; a stable metabolite of TXA[sub 2]) into the perfusate were measured. The level of portal pressure was higher at 5 h following T-H compared with 2 h after T-H and sham. The portal pressure was inversely correlated to the amount of bile production. Furthermore, the bile flow was significantly correlated to the hepatic damage as evidenced by release of lactate dehydrogenase into the perfusate. The level of ET-1 at 5 h following T-H in the perfusate after 30 min of recirculation did not show any difference from sham. However, the levels of TXB[sub 2] in the T-H group were significantly higher than those in sham at that interval. These results indicate that the increased release of TXA[sub 2] but not ET-1 following T-H might be responsible for producing the increased portal resistance, decreased bile production, and hepatic damage. [ABSTRACT FROM AUTHOR]

Hypothesis: Sex differentially influences heme oxygenase (HO) expression following trauma and hemorrhagic shock. Design: Prospective controlled animal study. Setting: A university laboratory. Interventions: Female Sprague-Dawley rats in the proestrus stage of their estrus cycle and male rats underwent a 5-cm midline laparotomy (ie, induction of soft tissue trauma) and were bled to a mean arterial blood pressure of 35 mm Hg for approximately 90 minutes, after which they were resuscitated with Ringer lactate solution (4 × the shed blood volume). In another group of animals, tin protoporphyrin IX was used to block HO activity. Main Outcome Measures: Liver samples were collected for analysis of HO expression and activity, plasma samples were collected, and alanine transaminase levels were determined 5 hours after resuscitation. Portal pressure and bile production were measured in vivo 5 hours after resuscitation. Results: Trauma and hemorrhage induced a 2-fold increase in hepatic HO1 expression (the inducible form of HO) in proestrus females compared with males. Hepatic expression of HO2 (a constitutive isoform of HO) was unaffected by sex or trauma and hemorrhage. Blockade of HO in vivo with tin protoporphyrin IX abolished the sex differences caused by diverse HO1 expression. Treatment with tin protoporphyrin IX also elevated the portal pressure, decreased bile production, and increased alanine transaminase to similar levels in proestrus females and males following trauma and hemorrhage. Conclusions: Sex influences the hepatic expression of HO1 following trauma and hemorrhage. The enhanced induction of HO1 expression and activity in females after trauma and hemorrhage may attenuate hepatocellular dysfunction and injury by maintaining microcirculation via the increased production of carbon monoxide. [ABSTRACT FROM AUTHOR]

The activation of a pro-inflammatory cascade after burn injury appears to be important in the development of subsequent immune dysfunction, susceptibility to sepsis and multiple organ failure. Macrophages are major producers of pro-inflammatory mediators and their productive capacity for these mediators is markedly enhanced following thermal injury. Thus, macrophage hyperactivity (as defined by increased productive capacity for pro-inflammatory mediators) appears to be of critical importance in the development of post-burn immune dysfunction. This review will focus on the current state of knowledge with regards to the role of macrophages in the development of post-burn immune dysfunction. Particular areas of discussion include: nitric oxide synthase (NOS) and cyclooxygenase (COX) enzyme systems, macrophages and the T-helper (Th)-1/Th-2 cytokine responses, alterations in macrophages signal transduction and a potential role for γ/δ T-cells in the development of macrophage hyperactivity following thermal injury. A more comprehensive understanding of the relationship between macrophage activity and post-burn immune dysfunction will hopefully provide the basis for improved therapeutic regimes in the treatment of burn patients. [Copyright &y& Elsevier]

Examines the effectivity of estrogen pretreatment in the management hypoxia-induced immune depression in males. Discussion on the physiological effects of hypoxemia; Impact of elevated systemic estradiol levels on immune depression; Usefulness of the sex hormone in the prevention of hypoxemia during surgery.

Male gender and age appear to be causative factors in development of immunodepression and septic complications following trauma-haemorrhage. Studies have demonstrated that administration of the sex hormone prolactin following trauma-haemorrhage in male mice prevents immunodepression. Since the thymus is the primary location of the T-cell-lymphopoiesis, we investigated the effect of trauma-haemorrhage to thymic prolactin-receptor (PRLr)-expression in male and proestrus female mice in three different age groups (young, adult, aged) by flow cytometry and PCR. C3H/HeN mice were subjected to laparotomy (i.e., soft-tissue trauma) and hemorrhagic shock (35±5 mmHg for 90 min, then resuscitated) or sham operation. Twenty-four hours later thymocytes were isolated. Trauma-haemorrhage upregulated PRLr expression in young and mature mice of both genders, however, the increase was attenuated in females. In contrast, in aged mice PRLr expression was elevated in both genders, independent of trauma-haemorrhage and was not further increased under such conditions. These findings suggest that the gender dimorphism in the immune response to trauma-haemorrhage may in part be related to differences in thymic PRLr expression under such conditions. [Copyright &y& Elsevier]

Studies have shown that both animal tissue-fixed immune cells and human peripheral blood mononuclear cell (PBMC) functions are altered after burn injury. Additional studies suggest that the burn injury-induced alterations in these divergent cell populations from different species are similar. It remains unknown, however, whether the observed changes in animal tissue-fixed immune cell function following thermal injury also occurs to a similar extent in the PBMC population. The aim of our study was to compare PBMC and tissue-fixed immune cell functions from the same animal using a murine burn model. At 7 days post-burn, mice were more susceptible to sepsis and delayed type hypersensitivity responses were suppressed. Splenocytes isolated from injured mice displayed suppressed proliferation and increased IL-10 production. In contrast, PBMC from injured mice displayed suppressed proliferation, IL-2 and IFN-γ production. Splenic macrophage nitric oxide, PGE2, TNF-α, IL-6 and IL-10 production was enhanced post-burn and IL-12 production was suppressed. PBMC from such animals displayed enhanced PGE2 production and suppressed IL-6 and IL-12 production. These results indicate that while an immunosuppressive Th2 phenotype (increased IL-10 and/or suppressed IL-2, IFN-γ) was induced in both the splenic and PBMC compartments post-injury, differential expression and dimorphism in the response also exists. Thus, the assessment of only PBMC function in burn patients may not accurately reflect the patient''s actual immune status at the tissue level. [Copyright &y& Elsevier]

Resistance of macrophages to the suppressive effect of interleukin-10 following thermal injury. Am J Physiol Cell Physiol 281: Cl180-Cl187, 2001.—The activation of a macrophage (Mφ)-dependent proinflammatory cascade following thermal injury plays an imporrant role in the development of immunosuppression and increased susceptibility to subsequent sepsis in burn patients. In contrast, although interleukin (IL)-10, an antiinflammatory cytokine that can downregulate Mφ activity, has also been implicated in postburn immune dysfunction, its role in the regulation of M[sub φ] function postburn remains unclear. To study this, C57BL/6 female mice were subjected to a 25% total body surface area third-degree scald burn, and splenic Mφs were isolated 7 days later. Lipopolysaccharide (LPS)-stimulated IL-10, IL-6, tumor necrosis factor (TNF)-α, and nitric oxide (NO) production were significantly increased in the burn group compared with shams. Blockade of endogenous IL-10 activity enhanced IL-6 and TNF-α release, but not NO release, in both groups. The addition of exogenous IL-10 to the Mφ cultures dose dependently suppressed production of these inflammatory mediators in both groups. The timing of IL-10 addition to the cultures in relation to LPS stimulation, however, was critical. The suppressive effect of exogenous IL-10 was attenuated in both groups when the cells were exposed to IL-10 at 4-6 h after LPS stimulation; however, Mφs from injured mice were significantly better able to maintain inflammatory mediator-productive capacity. The resistance of Mφs from injured mice to IL-10-mediated suppression correlated with decreased IL-10 receptor (IL10R) expression and increased CDllb expression. These findings suggest that Mφs, following thermal injury, display resistance to suppression by IL-10 due in part to downregulation of IL-10R expression. [ABSTRACT FROM AUTHOR]

We previously reported an early surge in high mobility group box protein 1 (HMGB1) levels in a polytrauma (PT) rat model. This study investigates the association of HMGB1 levels in mediating PT associated dysregulated immune responses and its influence on the cellular levels of receptor for advanced glycation end products (RAGE) and toll-like receptor 4 (TLR4). Using the same PT rat model treated with anti-HMGB1 polyclonal antibody, we evaluated changes in circulating inflammatory cytokines, monocytes/macrophages and T cells dynamics and cell surface expression of RAGE and TLR4 at 1, 3, and 7 days post-trauma (dpt) in blood and spleen. Notably, PT rats demonstrating T helper (Th)1 and Th2 cells type early hyper-inflammatory responses also exhibited increased monocyte/macrophage counts and diminished T cell counts in blood and spleen. In blood, expression of RAGE and TLR4 receptors was elevated on CD68+ monocyte/macrophages and severely diminished on CD4+ and CD8+ T cells. Neutralization of HMGB1 significantly decreased CD68+ monocyte/macrophage counts and increased CD4+ and CD8+ T cells, but not γδ+TCR T cells in circulation. Most importantly, RAGE and TLR4 expressions were restored on CD4+ and CD8+ T cells in treated PT rats. Overall, findings suggest that in PT, the HMGB1 surge is responsible for the onset of T cell exhaustion and dysfunction, leading to diminished RAGE and TLR4 surface expression, thereby possibly hindering the proper functioning of T cells. [ABSTRACT FROM AUTHOR]

Focuses on a study which determined whether hypoxemia increases nitric oxide (NO) production by macrophages in vivo and explores whether the increase was due to elevated macrophage-inducible NO synthase. How hypoxemia induces NO production by macrophages; Effects of hypoxia on NO production by splenic macrophages; How macrophage iNOS messenger RNA is expressed following hypoxemia.

Hypothesis: Uninjured skin contributes to the elevation in circulating levels of proinflammatory cytokines seen following severe injury. Design: Male C3H/HeN mice underwent trauma, trauma-hemorrhage and resuscitation, or closed long-bone fracture. Serum, skin, and liver samples were harvested at designated times after experimental treatment. Main Outcome Measures: Levels of interleukin (IL) 1β, IL-6, and tumor necrosis factor α (TNF-α) were determined in serum and skin cultures at 1, 8, and 24 hours after trauma-hemorrhage. The RNA was isolated from liver and skin samples at 1, 2, 4, 8, and 24 hours from all 3 experimental groups, and gene expression of the cytokines was determined. Results: Remote (nontraumatized) skin from trauma-hemorrhage animals released significantly more IL-6 and TNF-α into culture supernatants at 1 and 24 hours and significantly more IL-1β at 1, 8, and 24 hours than did skin from sham animals. Serum levels of all 3 cytokines were significantly elevated at 1 and 24 hours after trauma-hemorrhage relative to sham animals. Gene expression of all 3 cytokines was detected in skin and liver following trauma-hemorrhage. Furthermore, gene expression of all 3 cytokines was detected in uninjured skin after soft tissue trauma and closed long-bone fracture. Conclusions: Proinflammatory cytokine gene expression is up-regulated in uninjured skin following trauma, trauma-hemorrhage, and long-bone fracture. This increase in gene expression correlates with increased cytokine production by cultured skin as well as increased circulating cytokine levels. These results suggest that uninjured skin may also contribute to the rise in circulating cytokine levels seen after injury. [ABSTRACT FROM AUTHOR]