Downregulation of migration inhibitory factor is critical for estrogen-mediated attenuation of lung tissue damage following trauma-hemorrhage

Although studies have shown that 17β-estradiol (E2) prevents neutrophil infiltration and organ damage following trauma-hemorrhage, the mechanism by which E2inhibits neutrophil transmigration remains unknown. Macrophage migration inhibitory factor (MIF) is thought to play a central role in exacerbation of inflammation and is associated with lung injury. MIF regulates the inflammatory response through modulation of Toll-like receptor 4 (TLR4). Activation of TLR4 results in the release of proinflammatory cytokines and chemokines, which induce neutrophil infiltration and subsequent tissue damage. We hypothesized that E2mediates its salutary effects in the lung following trauma-hemorrhage via negative regulation of MIF and modulation of TLR4 and cytokine-induced chemotaxis. C3H/HeOuJ mice were subjected to trauma-hemorrhage (mean blood pressure 35 ± 5 mmHg for ∼90 min, then resuscitation) or sham operation. Mice received vehicle, E2, or E2in combination with recombinant mouse MIF protein (rMIF). Trauma-hemorrhage increased lung MIF and TLR4 protein levels as well as lung and systemic levels of cytokines/chemokines. Treatment of animals with E2following trauma-hemorrhage prevented these changes. However, administration of rMIF protein with E2abolished the E2-mediated decrease in lung TLR4 levels, lung and plasma levels of IL-6, TNF-α, monocyte chemoattractant protein-1, and keratinocyte-derived chemokine (KC). Administration of rMIF protein also prevented E2-mediated reduction in neutrophil influx and tissue damage in the lungs following trauma-hemorrhage. These results suggest that the protective effects of E2on lung injury following trauma-hemorrhage are mediated via downregulation of lung MIF and TLR4-induced cytokine/chemokine production.

Acute alcohol intoxication increases interleukin-18-mediated neutrophil infiltration and lung inflammation following burn injury in rats

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 IL-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.

17 Beta-estradiol normalizes Toll receptor 4, mitogen activated protein kinases and inflammatory response in epidermal keratinocytes following trauma-hemorrhage

Trauma-hemorrhage produces immunodepression in males but not in proestrus females and this difference is due to the presence of high estrogen in proestrus females. Although skin is the largest immunological organ of the body and is considered the first line of defense, no study to-date has examined whether trauma-hemorrhage has any effects on keratinocytes which are the major epidermal cell type (>90%) of skin. We therefore examined whether epidermal keratinocytes inflammatory response and the signal transduction pathways involved in the inflammatory response are altered following trauma-hemorrhage. C3H/HeN mice were subjected to trauma-hemorrhage and 2h thereafter; keratinocytes were harvested and stimulated with LPS for 24h (5 microg/ml). Inflammatory mediators, Toll-like receptor (TLR) and myeloid differentiation adaptor protein (MyD88) expression, and the activation of mitogen-activated protein kinase (MAPK) were determined. Trauma-hemorrhage increased the production of IL-6, IL-10, IL-12 and TNF-alpha enhanced the expression of TLR4, MyD88 as well as the activation of MAPK proteins (p38, ERK and JNK) in epidermal keratinocytes. However, administration of a single dose of 17beta-estradiol following trauma-hemorrhage prevented the increase in these inflammatory parameters under those conditions. These findings suggest that 17beta-estradiol normalizes epidermal keratinocytes inflammatory responses following trauma-hemorrhage by preventing the upregulation of TLR4-mediated MAPK activation.

The role of MAPK in Kupffer cell toll-like receptor (TLR) 2-, TLR4-, and TLR9-mediated signaling following trauma-hemorrhage

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 approximately 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-alpha, 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-alpha, 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-alpha 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-alpha 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.

Flutamide attenuates pro-inflammatory cytokine production and hepatic injury following trauma-hemorrhage via estrogen receptor-related pathway

OBJECTIVE

To determine the mechanism by which flutamide administration following trauma-hemorrhage (T-H) decreases cytokine production and hepatic injury under those conditions.

SUMMARY BACKGROUND DATA

Although studies have demonstrated that flutamide administration following T-H improves hepatic and immune functions, the mechanism by which flutamide produces the salutary effects remains unknown.

METHODS

Male Sprague-Dawley rats underwent a 5-cm laparotomy and hemorrhagic shock (40 mm Hg for approximately 90 minutes), followed by resuscitation with 4 times the shed blood volume in the form of Ringer's lactate. Flutamide (25 mg/kg body weight, sc) was administered at the middle of resuscitation and animals were killed 2 hours thereafter. To block estrogen receptor (ER), ER antagonist ICI 182,780 was administrated with flutamide.

RESULTS

Hepatic injury, myeloperoxidase activity, nuclear factor-kappaB (NF-kappaB) DNA binding activity and protein expression of intercellular adhesion molecule-1, and cytokine-induced neutrophil chemoattractant (CINC-1 and CINC-3) markedly increased following T-H. Hepatic mRNA and plasma IL-6 levels were also elevated following T-H. The alterations in these parameters induced by T-H were significantly attenuated by flutamide administration. The decreased plasma estradiol levels following T-H were restored to sham levels in the flutamide-treated T-H animals. Coadministration of ICI 182,780 prevented those salutary effects of flutamide administration on pro-inflammatory responses and hepatic injury following T-H.

CONCLUSION

These findings suggest that the reduction in the production of pro-inflammatory mediators and hepatic injury produced by flutamide administration following T-H is likely due to the down-regulation in hepatic NF-kappaB DNA binding activity. Moreover, the salutary effects of flutamide administration appear to be mediated at least in part via ER-related pathway.

Salutary effects of 17beta-estradiol on T-cell signaling and cytokine production after trauma-hemorrhage are mediated primarily via estrogen receptor-alpha

Although 17beta-estradiol (E2) administration following trauma-hemorrhage prevents the suppression in splenocyte cytokine production, it remains unknown whether the salutary effects of 17beta-estradiol are mediated via estrogen receptor (ER)-alpha or ER-beta. Moreover, it is unknown which signaling pathways are involved in 17beta-estradiol's salutary effects. Utilizing an ER-alpha- or ER-beta-specific agonist, we examined the role of ER-alpha and ER-beta in E2-mediated restoration of T-cell cytokine production following trauma-hemorrhage. Moreover, since MAPK, NF-kappaB, and activator protein (AP)-1 are known to regulate T-cell cytokine production, we also examined the activation of MAPK, NF-kappaB, and AP-1. Male rats underwent trauma-hemorrhage (mean arterial pressure 40 mmHg for 90 min) and fluid resuscitation. ER-alpha agonist propyl pyrazole triol (PPT; 5 microg/kg), ER-beta agonist diarylpropionitrile (DPN; 5 microg/kg), 17beta-estradiol (50 microg/kg), or vehicle (10% DMSO) was injected subcutaneously during resuscitation. Twenty-four hours thereafter, splenic T cells were isolated, and their IL-2 and IFN-gamma production and MAPK, NF-kappaB, and AP-1 activation were measured. T-cell IL-2 and IFN-gamma production was decreased following trauma-hemorrhage, and this was accompanied with a decrease in T-cell MAPK, NF-kappaB, and AP-1 activation. PPT or 17beta-estradiol administration following trauma-hemorrhage normalized those parameters, while DPN administration had no effect. Since PPT, but not DPN, administration following trauma-hemorrhage was as effective as 17beta-estradiol in preventing the T-cell suppression, it appears that ER-alpha plays a predominant role in mediating the salutary effects of 17beta-estradiol on T cells following trauma-hemorrhage, and that such effects are likely mediated via normalization of MAPK, NF-kappaB, and AP-1 signaling pathways.

Does estrogen contribute to the hepatic regeneration following portal branch ligation in rats?

The aim of this study was to determine whether estrogen plays any role in the hepatic regeneration of nonligated lobe following portal branch ligation (PBL). Male rats were subjected to PBL on the left and middle lobes. Two and 7 days after PBL, the rats were killed and blood and liver samples were analyzed. Sham animals underwent only laparotomy. The serum estradiol levels were significantly elevated on day 2 following PBL and returned to normal levels on day 7. The expression of estrogen receptors (ER) in the liver evaluated by Western blotting did not show any change in the nonligated lobe compared with shams. Immunohistochemical study for ER showed a predominant ER expression in the hepatocyte nucleus in periportal area (zone 1), although there was no apparent difference in the amount and expression pattern between sham and PBL. However, chronic inhibition of ER by an ER antagonist (ICI 182,780) showed a significantly lower regeneration rate of the nonligated lobe compared with vehicle treatment. Liver regeneration-associated genes also were less activated in the ICI group. Moreover, portal venous flow, determined by fluorescent microsphere injection, was significantly lower in the ICI group compared with vehicle group. These changes correlated with the attenuated expression of endothelial nitric oxide synthase mRNA in both superior mesenteric arteries and veins. In conclusion, these results indicate that the estrogen's contribution on hepatic regeneration following PBL is at least partly mediated through maintaining mesenteric blood flow by mesenteric endothelial nitric oxide synthase upregulation rather than directly activating liver regeneration in the liver.

INFLUENCE OF SEX AND AGE ON MODS AND CYTOKINES AFTER MULTIPLE INJURIES

Although salutary effects of female sex steroids have been demonstrated not only in proestrus females but also in male animals treated with estradiol in different models of trauma, it remains unknown whether sex hormones influence post-traumatic immune response in humans. We therefore investigated the effect of sex and age on organ dysfunction and clinical course in patients with multiple injuries. Polytraumatized patients (injury severity score>16) between 16 and 65 years old admitted to the Hannover Medical School Level 1 trauma center between January 1997 and December 2001 were included. Marshall Score for multiple organ dysfunction syndrome (MODS) was calculated for at least 14 days. The length of stay in intensive care unit and the ventilator days were recorded in addition to the number of transfusions the patient received. A total of 106 males and 37 females were included in the study. Patients with MODS had increased plasma levels of IL-6, IL-8, and IL-10. Furthermore, patients with organ dysfunction had more frequent sepsis and higher mortality rates. In addition, MODS was associated with extended length of stay in the intensive care unit and increased ventilator days. Females not older than 50 years with an injury severity score greater than 25 suffered significantly less MODS and sepsis compared with age-matched males. Moreover, they had significantly lower plasma cytokines. Thus, in this prospective study, sex difference was confirmed in MODS and sepsis, with a benefit observed in females. Although the levels of sex steroids were not measured, it seems that the protective effects may be due to estrogen effects on plasma cytokines. This suggestion is based on the fact that such salutary effects were apparent predominantly in premenopausal females.

Mitochondria play an important role in 17beta-estradiol attenuation of H(2)O(2)-induced rat endothelial cell apoptosis

Studies have shown salutary effects of 17beta-estradiol following trauma-hemorrhage on different cell types. 17beta-Estradiol also induces improved circulation via relaxation of the aorta and has an anti-apoptotic effect on endothelial cells. Because mitochondria play a pivotal role in apoptosis, we hypothesized that 17beta-estradiol will maintain mitochondrial function and will have protective effects against H(2)O(2)-induced apoptosis in endothelial cells. Endothelial cells were isolated from rats' aorta and cultured in the presence or absence of H(2)O(2), a potent inducer of apoptosis. In additional studies, endothelial cells were pretreated with 17beta-estradiol. Flow cytometry analysis revealed H(2)O(2)-induced apoptosis in 80.9% of endothelial cells; however, prior treatment of endothelial cells with 17beta-estradiol resulted in an approximately 40% reduction in apoptosis. This protective effect of 17beta-estradiol was abrogated when endothelial cells were cultured in the presence ICI-182780, indicating the involvement of estrogen receptor (ER). Fluorescence microscopy revealed a 17beta-estradiol-mediated attenuation of H(2)O(2)-induced mitochondrial condensation. Western blot analysis demonstrated that H(2)O(2)-induced cytochrome c release from mitochondrion to cytosol and the activation of caspase-9 and -3 were decreased by 17beta-estradiol. These findings suggest that 17beta-estradiol attenuated H(2)O(2)-induced apoptosis via ER-dependent activation of caspase-9 and -3 in rat endothelial cells through mitochondria.

TLR4 regulates Kupffer cell chemokine production, systemic inflammation and lung neutrophil infiltration following trauma-hemorrhage

Toll-like receptors (TLR) recognize not only microbial products, but also danger signals released from damaged tissues. Although we have previously shown that TLR4 is upregulated following trauma hemorrhage, the exact role of TLR4 in the posttraumatic immune response is unclear. To study this, C3H/HeOuJ (functional TLR4) or C3H/HeJ (TLR4 mutant) mice were subjected to laparotomy and hemorrhagic shock followed by resuscitation with 4x the shed blood volume in the form of Ringer's lactate. Sham operated mice underwent same surgical procedure, but neither hemorrhage nor resuscitation was performed. Four hours after resuscitation, the mice were sacrificed, plasma and lungs were collected and Kupffer cells were isolated. Plasma chemokine (MCP-1 and KC) levels, Kupffer cell chemokine production, and lung chemokine content were determined. Lung neutrophil infiltration was assessed by tissue content of myeloperoxidase. The chemokine levels in plasma, Kupffer cell supernatants and lung tissue were elevated in C3H/HeOuJ mice subjected to trauma hemorrhage compared to shams. No such changes were observed in C3H/HeJ mice undergoing trauma hemorrhage. Mice with functional TLR4 expression showed elevated lung neutrophil infiltration following trauma hemorrhage, which was not observed in TLR4 mutant mice. These findings suggest that functional TLR4 signaling is critical in mediating the inflammatory response following trauma hemorrhage. Thus, modulation of the TLR4 after injury may serve as a future therapeutic target in trauma patients.

Effects of 17beta-estradiol and flutamide on splenic macrophages and splenocytes after trauma-hemorrhage

Since splenic immune functions are depressed in metestrus females following trauma-hemorrhage, we hypothesized that administration of the androgen receptor antagonist flutamide at the onset of resuscitation will maintain the immune function of the spleen following trauma-hemorrhage. Female C57BL6/J mice (metestrus state, 8-12 weeks old), underwent laparotomy and hemorrhagic shock (35.0+/-5.0 mm Hg for 90 min) and received 17beta-estradiol (50 microg/25 g), flutamide (625 microg/25 g) or 17beta-estradiol+flutamide. Four hours after resuscitation, the in vitro productive capacity of different cytokines (TNF-alpha, IL-6, IL-10, and IFN-gamma) by splenic MPhi and splenocytes were determined by flow cytometry. A significantly decreased cytokine production by both splenocytes and splenic MPhi was observed following trauma-hemorrhage compared to shams. Administration of 17beta-estradiol, flutamide and 17beta-estradiol+flutamide following trauma-hemorrhage resulted in a significant increase in the in vitro IL-6 release by splenic MPhi. The TNF-alpha productive capacity, however, was only restored by 17beta-estradiol and 17beta-estradiol+flutamide administration following trauma-hemorrhage. No significant effect of either treatment was observed with regard to the suppressed splenic MPhi IL-10 release. Anti-CD3 stimulation, administration of 17beta-estradiol and 17beta-estradiol+flutamide, but not the administration of flutamide alone resulted in a significant increased release of TNF-alpha, IL-6 and IFN-gamma compared to vehicle-treated animals. No significant effect of either treatment was found on IL-10 productive capacity. These results collectively suggest that flutamide administration following trauma-hemorrhage in females has beneficial effects on splenic immune function. However, flutamide administration in combination with estrogen does not provide any significant, additional effects over 17beta-estradiol administration alone.

Tissue compartment-specific role of estrogen receptor subtypes in immune cell cytokine production following trauma-hemorrhage

Although 17β-estradiol administration following trauma-hemorrhage attenuates plasma cytokines and alteration in immune cell cytokine production, it is not known whether the salutary effects are mediated via estrogen receptor (ER)-α or ER-β. Accordingly, we examined which ER subtype predominantly mediates the salutary effects of 17β-estradiol on systemic inflammatory response/immune cell cytokine production in various tissues following trauma-hemorrhage. Male rats underwent trauma-hemorrhage (mean blood pressure: 40 mmHg for 90 min) and fluid resuscitation. The ER-α agonist propyl pyrazole triol (PPT; 5 μg/kg), the ER-β agonist diarylpropionitrile (DPN; 5 μg/kg), 17β-estradiol (50 μg/kg), or vehicle (10% DMSO) was injected subcutaneously during resuscitation, and various measurements were made 24 h thereafter. 17β-Estradiol or PPT administration following trauma-hemorrhage prevented the increase in plasma IL-6 and IL-10 levels that were observed in vehicle-treated animals. IL-6 and TNF-α production by Kupffer cells increased; however, splenic macrophages (SMΦ), alveolar macrophages (AMΦ), and peripheral blood mononuclear cells (PBMC) had decreased release of these cytokines after trauma-hemorrhage. IL-10 production, however, increased in all macrophage populations. Administration of 17β-estradiol following trauma-hemorrhage prevented all of these alterations. PPT had the same effects as 17β-estradiol on IL-6 and TNF-α production by Kupffer cells and SMΦ, and DPN had the same effects on AMΦ and PBMC. The same effects as 17β-estradiol on IL-10 production were observed by PPT on Kupffer cells and DPN on PBMC. Both agonists were equally effective on SMΦ and AMΦ. Thus ER subtypes have tissue compartment-specific roles in mediating the effects of 17β-estradiol on immune cell functions following trauma-hemorrhage.

Liver cytokine production and ICAM-1 expression following bone fracture, tissue trauma, and hemorrhage in middle-aged mice

Although studies have indicated that hemorrhagic shock and resuscitation produces hepatic damage by mechanisms involving adhesion molecules in endothelial cells and hepatocytes, it is not known if there is any difference in the extent of hepatic damage following bone fracture, soft tissue trauma, and hemorrhage (Fx-TH) between young and middle-aged animals. To study this, young (6-8 wk) and middle-aged (approximately 12 mo) C3H/HeN male mice were subjected to a right lower leg fracture, soft tissue trauma, (i.e., midline laparotomy), and hemorrhage (blood withdrawal to decrease the blood pressure to 35 +/- 5 mmHg for 90 min) followed by resuscitation with four times the shed blood volume in the form of lactated Ringer solution. Mice were euthanized 24 h later, and liver tissues were harvested. Total bilirubin levels in the hepatocyte extract increased markedly following Fx-TH in both groups of mice; however, the increase in middle-aged mice was significantly higher compared with young mice. TNF-alpha and IL-6 levels in the hepatocyte extract following Fx-TH increased significantly in middle-aged mice but remained unchanged in young mice. IL-10 levels significantly decreased in middle-aged mice following Fx-TH but remained unchanged in young mice. Kupffer cells from middle-aged mice produced significantly higher IL-6 and IL-10 levels compared with young mice. Protein levels and mRNA expression of ICAM-1 in hepatocytes were also significantly higher in middle-aged mice compared with young mice following Fx-TH. These results collectively suggest that the extent of hepatic damage following Fx-TH is dependent on the age of the subject.

Young and middle-age associated differences in cytokeratin expression after bone fracture, tissue trauma, and hemorrhage

BACKGROUND

This study examined whether there is any difference in the lung cytokine and cytokeratin 19 levels between young and middle-aged mice after bone fracture and soft-tissue trauma hemorrhage (Fx-TH).

METHODS

Young (6-8 weeks) and middle-aged (12 months) C3H/HeN male mice were subjected to right lower leg fracture, trauma hemorrhage (mean arterial blood pressure to 35 +/- 5 mm Hg for 90 minutes), and resuscitation.

RESULTS

The tumor necrosis factor alpha level in the lung increased significantly at 2 hours after Fx-TH in both young and middle-aged mice, whereas at 24 hours the levels remained significantly higher in middle-aged mice. Interleukin-6 levels increased significantly 24 hours after Fx-TH in both groups, whereas interleukin-10 levels increased only in middle-aged mice at 24 hours under those conditions. Monocyte chemoattractant protein-1 levels increased significantly 2 hours after Fx-TH. The protein and messenger RNA levels of cytokeratin 19 were significantly higher in middle-aged mice compared with young mice after Fx-TH.

CONCLUSION

These results suggest that age influences the lung inflammatory response after Fx-TH.

17β-Estradiol modulates vasoconstriction induced by endothelin-1 following trauma-hemorrhage

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-β-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-β 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.

Impact of sex and age on bone marrow immune responses in a murine model of trauma-hemorrhage

Although studies have demonstrated that trauma markedly alters the bone marrow immune responses, sex and age are crucial determinants under such conditions and have not been extensively examined. To study this, 21- to 27-day-old (premature), 6- to 8-wk-old (mature), and 20- to 24-mo-old (aged) male and female (proestrus) C3H/HeN mice were sham operated or subjected to trauma (i.e., midline laparotomy) and hemorrhagic shock (30 ± 5 mmHg for 90 min) followed by fluid resuscitation. Twenty-four hours after resuscitation, bone marrow cells were harvested. Trauma-hemorrhage induced an increased number of the early pluripotent stem cell-associated bone marrow cell subsets (Sca1+CD34−CD117+/−lin+/−) in young mice. The CD117+proportion of these cell subsets increased in mature proestrus females, but not in males. Aged males displayed significant lower numbers of Sca1+CD34−CD117+/−lin+/−cells compared with young male mice. Trauma-hemorrhage also increased development of granulocyte/macrophage progenitor cells (CD11b+Gr-1+). Proliferative responses to granulocyte macrophage colony-stimulating factor were maintained in mature and aged proestrus females, but decreased in young mice and mature males. Augmented differentiation into monocyte/macrophage lineage in mature and aged proestrus females was observed and associated with the maintained release of TNF-α and IL-6. Conversely, increased IL-10 and PGE2production was observed in the male trauma-hemorrhage groups. Thus, sex- and age-specific effects in bone marrow differentiation and immune responses after trauma-hemorrhage occur, which are likely to contribute to the sex- and age-related differences in the systemic immune responses under such conditions.

Estrogen-mediated activation of non-genomic pathway improves macrophages cytokine production following trauma-hemorrhage

Although 17beta-estradiol (E2) attenuates the alterations in Kupffer cells and splenic macrophages (MPhi) cytokine production following trauma-hemorrhage, the mechanism by which this occurs remains unknown. Utilizing a cell-impermeable E2 conjugated with BSA (E2-BSA), we examined the non-genomic effects of E2 on the above two cell population cytokine production, MAPK and transcription factors activation following trauma-hemorrhage. Male Sprague-Dawley rats underwent trauma-hemorrhage (mean BP 40 mmHg for 90 min, then resuscitation). E2, E2-BSA (1 mg/kg E2) with or without an estrogen receptor antagonist (ICI 182,780), or vehicle was administrated during resuscitation. Two hrs thereafter, Kupffer cells and SMPhi production of IL-6, TNF-alpha, and IL-10, activation of MAPK (p38, ERK-1/2, and JNK), and transcription factors (NF-kappaB and AP-1) were determined. IL-6, TNF-alpha, and IL-10 productive capacity, MAPK, and transcription factors activation increased in Kupffer cells while they decreased in SMPhi following trauma-hemorrhage. However, E2 administration normalized all of these alterations. Although E2-BSA also attenuated the alterations in cytokine production/transcription factors, the values were higher in Kupffer cells and lower in SMPhi compared to shams. In contrast, E2-BSA prevented trauma-hemorrhage-mediated changes in MAPK activation to the same extent as E2. Co-administration of ICI 182,780 abolished E2-BSA effects. Although some MAPK inhibitors suppressed cytokine production, the inhibitor effectiveness was dependent on cytokine, cell type and animal condition (trauma-hemorrhage or sham). Thus, E2 effects on Kupffer cells and SMPhi cytokine production and transcription factors activation following trauma-hemorrhage are mediated at least in part via non-genomic pathway and these non-genomic effects are likely mediated via MAPK pathways.

Surgical Trauma-Induced Adrenal Insufficiency is Associated with Postoperative Inflammatory Responses

The hypothalamic-pituitary-adrenal axis is an essential component for the maintenance of homeostasis following trauma. Major surgical trauma often induces overwhelming inflammatory responses leading to sepsis and organ dysfunction. This study was designed to evaluate the adrenal responses both before and after various degrees of surgical trauma and to determine the incidence of postoperative relative adrenal insufficiency resulting in the marked inflammatory response often associated with postoperative complications. Fifty-one surgical patients were divided into groups who underwent major, moderate, and minor surgeries. Before the operation and during resting conditions, a short corticotropin (ACTH) stimulation test was performed in each patient. The postoperative concentrations of serum cortisol, interleukin (IL)-6, IL-10, C-reactive protein (CRP), and plasma ACTH were measured. Fifty of 51 patients were identified as responders to ACTH. The postoperative cortisol levels were the same as those obtained by ACTH stimulation in highly and moderately stressful surgeries. The increases in postoperative IL-6 and CRP levels were greatest with major surgery, intermediate with moderate surgery, and least with minor surgery. Furthermore, plasma ACTH levels increased after major and moderate surgeries; however, there was no significant differences in postoperative serum IL-10 levels. Systemic inflammatory response syndrome (SIRS) was found in 11 of 17 patients (64.7%) who underwent major surgery and in 4 of 16 patients (25%) who underwent moderate surgery (p=0.037). The duration of SIRS was significantly longer in patients undergoing major surgery (62+/-20 hrs) than in patients undergoing moderate surgery (21+/-3 hrs, p=0.038). Postoperative complications were more frequent in patients undergoing major surgery (41.2%) than in patients undergoing moderate surgery (6.3%, p=0.039). Furthermore, there were significant differences in the length of the postoperative stay among the three groups (p<0.01). One nonresponder had serious postoperative inflammatory complications. These results suggest that a short ACTH stimulation test performed preoperatively is a helpful method for determining the maximal cortisol response to surgical trauma and to identify high-risk individuals and that a relative postoperative adrenal insufficiency may be closely related to the decreased cortisol secretion following major surgical trauma.

Cecal ligation and puncture

The model of cecal ligation and puncture (CLP) in rodents has been used extensively to investigate the clinical settings of sepsis and septic shock. This model produces a hyperdynamic, hypermetabolic state that can lead to a hypodynamic, hypometabolic stage, and eventual death. Blood cultures are positive for enteric organisms very early after CLP. The model has been widely used over the past 26 years and is highly versatile in adapting to a range of severity and testing objectives. It is inexpensive to prepare and technically straightforward. Aspects of sepsis research investigated using CLP include energetics, metabolism, resuscitation, antibiotic therapy, microbial factors, cardiovascular responses, immune function, mediator release, and cytokine expression patterns. The challenge of the small circulating blood volume in rodents can be overcome by using micromethods that enable analysis of small volumes, or alternatively, by using a large number of animals to obtain serial samples.

17Beta-estradiol downregulates Kupffer cell TLR4-dependent p38 MAPK pathway and normalizes inflammatory cytokine production following trauma-hemorrhage

Although studies have shown that 17beta-estradiol (estradiol) normalized Kupffer cell function following trauma-hemorrhage, the mechanism by which E2 maintains immune function remains unclear. Activation of Toll-like receptor 4 (TLR4) initiates an inflammatory cascade, involving activation of p38 mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K), and nuclear factor-kappaB (NF-kappaB). This leads to the release of proinflammatory cytokines. Thus, we hypothesized that the salutary effects of estradiol on Kupffer cell function following trauma-hemorrhage are mediated via negative regulation of TLR4-dependent p38 MAPK and NF-kappaB. TLR4 mutant (C3H/HeJ) and wild type (C3H/HeOuJ) mice were subjected to trauma-hemorrhage (mean BP 35+/-5 mmHg approximately 90 min, then resuscitation) or sham operation. Administration of estradiol following trauma-hemorrhage in wild type mice decreased Kupffer cell TLR4 expression as well as prevented the phosphorylation of p38 MAPK and NF-kappaB. This was accompanied by normalization of Kupffer cell production capacities of IL-6, TNF-alpha, macrophage inflammatory protein (MIP)-1alpha, and MIP-2 and the decrease in plasma cytokine levels. In contrast, TLR4 mutant mice did not exhibit the increase in Kupffer cell p38 MAPK and NF-kappaB activation, cytokine production, or the increase in circulating cytokine levels following trauma-hemorrhage. No difference was observed in activation of PI3K among groups. These results suggest that the protective effect of estradiol on Kupffer cell function is mediated via downregulation of TLR4-dependent p38 MAPK and NF-kappaB signaling following trauma-hemorrhage, which prevents the systemic release of cytokines.

Anti-rat soluble IL-6 receptor antibody down-regulates cardiac IL-6 and improves cardiac function following trauma-hemorrhage

Although anti-IL-6-mAb down-regulates cardiac IL-6 and attenuates IL-6-mediated cardiac dysfunction following trauma-hemorrhage, it is not known whether blockade of IL-6 receptor will down-regulate cardiac IL-6 and improve cardiac function under those conditions. Six groups of male adult rats (275-325 g) were used: sham/trauma-hemorrhage+vehicle, sham/trauma-hemorrhage+IgG, sham/trauma-hemorrhage+anti-rat sIL-6R. Rats underwent trauma-hemorrhage (removal of 60% of the circulating blood volume and fluid resuscitation after 90 min). Vehicle (V), normal goat IgG or anti-rat sIL-6R (16.7 microg/kg BW) was administered intra-peritoneally in the middle of resuscitation. Two hours later, cardiac function was measured by ICG dilution technique; blood samples collected, cardiomyocytes isolated, and cardiomyocyte nuclei were then extracted. Cardiac IL-6, IL-6R, gp130, IkappaB-alpha/P-IkappaB-alpha, NF-kappaB, and ICAM-1 expressions were measured by immunoblotting. Plasma IL-6 and cardiomyocyte NF-kappaB DNA-binding activity were determined by ELISA. In additional animals, heart harvested and cardiac MPO activity and CINC-1 and -3 were also measured. In another group of rats, cardiac function was measure by microspheres at 24 h following trauma-hemorrhage. Cardiac function was depressed and cardiac IL-6, P-IkappaB-alpha, NF-kappaB and its DNA-binding activity, ICAM-1, MPO activity, and CINC-1 and -3 were markedly increased after trauma-hemorrhage. Moreover, cardiac dysfunction was evident even 24 h after trauma-hemorrhage. Administration of sIL-6R following trauma-hemorrhage: (1) improved cardiac output at 2 h and 24 h (p<0.05); (2) down-regulated both cardiac IL-6 and IL-6R (p<0.05); and (3) attenuated cardiac P-IkappaB-alpha, NF-kappaB, NF-kappaB DNA-binding activity, ICAM-1, CINC-1, -3, and MPO activity (p<0.05). IgG did not significantly influence the above parameters. Thus, IL-6-mediated up-regulation of cardiac NF-kappaB, ICAM-1, CINC-1, -3, and MPO activity likely contributes to altered cardiac function following trauma-hemorrhage. Since IL-6R blockade after trauma-hemorrhage down-regulates cardiac IL-6 and improves cardiac functions, blockade of IL-6R following trauma-hemorrhage appears to be a novel and effective adjunct for improving organ and cell function under those conditions.

MyD88 and Src are differentially regulated in Kupffer cells of males and proestrus females following hypoxia

Hypoxia produces sex dimorphic immune responses in males and proestrus females. Because Kupffer cells are the major source of proinflammatory cytokines, studies were conducted to discern IL-6 production in mouse Kupffer cells following hypoxia. Hypoxia enhances TLR4 expression in Kupffer cells irrespective of sex. However, MyD88 and Src expression in Kupffer cells decreased significantly after hypoxia in proestrus females, whereas Src protein expression and phosphorylation increased in males in concurrence with differences in IL-6 production. 17beta-estradiol administration elevated MyD88 and Src expression in males to levels in normoxic proestrus females. Administration of Src inhibitor in hypoxic males prevented increased IL-6 production. Thus, differential regulation of MyD88 and Src in males and females plays an important role in sex-specific immune response following hypoxia.