Deficiency of Omentin-1 leads to delayed fracture healing through excessive inflammation and reduced CD31hiEmcnhi vessels

Fracture healing is a complicated process affected by many factors, such as inflammatory responses and angiogenesis. Omentin-1 is an adipokine with anti-inflammatory properties, but whether omentin-1 affects the fracture healing process is still unknown. Here, by using global omentin-1 knockout (omentin-1^-/-) mice, we demonstrated that omentin-1 deficiency resulted in delayed fracture healing in mice, accompanied by increased inflammation and osteoclast formation, and decreased production of platelet-derived growth factor-BB (PDGF-BB) and osteogenesis-promoting vessels that are strongly positive for CD31 and Endomucin (CD31^hiEmcn^hi) in the fracture area. In vitro, omentin-1 treatment suppressed the ability of the tumor necrosis factor-α (TNF-α)-activated macrophages to stimulate multi-nuclear osteoclast formation, resulting in a significant increase in the generation of mono-nuclear preosteoclasts and PDGF-BB, a pro-angiogenic protein that is abundantly secreted by preosteoclasts. PDGF-BB significantly augmented endothelial cell proliferation, tube formation and migration, whereas direct treatment with omentin-1 did not induce obvious effects on angiogenesis activities of endothelial cells. Our study suggests a positive role of omentin-1 in fracture healing, which may be associated with the inhibition of inflammation and stimulation of preosteoclast PDGF-BB-mediated promotion of CD31^hiEmcn^hi vessel formation.

The impact of intramedullary nailing on the characteristics of the pulmonary neutrophil pool in rodents

PURPOSE

Dysregulation of polymorphonuclear neutrophil (PMN) biology is associated with the development of inflammatory complications after trauma, such as acute respiratory distress syndrome (ARDS). It has been demonstrated that intramedullary nailing is both associated with altered pulmonary neutrophil deposition and the occurrence of ARDS. This standardized study aimed to characterize the long-term remote neutrophil response in the lungs in case of a femur fracture and intramedullary nailing.

METHODS

A standardized rat model including intramedullary nailing and a femur fracture was utilized. Groups were terminated after observation times of three, seven and 14 days. Neutrophils were isolated from lung parenchyma and broncho-alveolar lavage fluid (BALF) and analyzed by flow cytometry. Absolute neutrophil numbers as well as membrane expression levels of CD11b, CD62L, and CD11a were compared.

RESULTS

Pulmonary neutrophil numbers were increased 3 days after intervention. Membrane expression levels of CD11b (P < 0.01), CD62L (P < 0.01), and CD11a (P = 0.06) on parenchymal PMNs increased as well after 3 days. Thereafter, values restored gradually to physiological levels. Furthermore, neutrophil activation status patterns between parenchymal and BALF neutrophil pools did not correlate.

CONCLUSIONS

The current study demonstrates that IMN and a femur fracture are associated with transient increased pulmonary PMN deposition, as well as a specific pattern of activation characterized by temporary increased selectin and integrin receptor expression on pulmonary neutrophils. This phenomenon might play an important role in the pathomechanism of ARDS after IMN. Moreover, we found striking differences between parenchymal and BALF-neutrophil populations, demonstrating the limited readout potential of BALF analysis to investigate the entire pulmonary neutrophil pool.

Monotrauma is associated with enhanced remote inflammatory response and organ damage, while polytrauma intensifies both in porcine trauma model

AIM

Severely injured patients experience substantial immunological stress upon traumatic insult. Next to the direct local tissue injury also other organs, which are not directly injured such as liver and lung, are frequently affected by a so-called remote organ damage (ROD) after trauma. Thus, we studied the inflammatory response of lung and liver either after isolated femur fracture as example for ROD, or after multiple trauma in a porcine polytrauma model.

METHODS

Twenty-four male pigs (Sus scrofa) underwent either isolated standardized femoral fracture (monotrauma, MT, n = 12) or polytrauma (PT, n = 12). PT consisted of a femur fracture, lung contusion, liver laceration, hemorrhagic shock, subsequent resuscitation and surgical fracture fixation. Six animals served as controls (sham). After 72 h inflammatory changes were determined by analyses of the interleukin (IL)-6 gene expression and tissue infiltration of polymorphonuclear leukocyte (PMN, myeloperoxidase staining). ROD in MT, and lung as well as liver damage in PT were assessed histologically by hematoxylin-eosin staining. Expression of phosphorylated p65 NF-κB was evaluated by immunohistology.

RESULTS

IL-6 increased in lungs and liver in both groups MT and PT, respectively, compared to sham. Similarly, PMN infiltration of the lungs and liver increased significantly after both MT and PT compared to sham. Histological evaluation demonstrated tissue damage notably in lungs after MT, while tissue damage after PT was found in both lung and liver after PT. p65 NF-κB tended to an increase upon MT, and was significantly enhanced after PT in both tissues.

CONCLUSION

Our data indicate that remote organ damage after MT notably in lungs was associated with an enhanced inflammatory response. Severe polytrauma substantially intensifies this response and organ damage in the underlying model.

Fracture initiates systemic inflammatory response syndrome through recruiting polymorphonuclear leucocytes

Fracture, a common type injury in trauma patients, often results in the development of the systemic inflammatory response syndrome (SIRS). Though the mechanism of the fracture-initiated SIRS still remains not well characterized, it is well documented that the polymorphonuclear leucocytes (PMN) play an important role in the inflammatory process. We hypothesize that fractures recruit PMN to the local tissue, which is followed by an increase in the number of peripheral PMN and initiation of SIRS. In the current study, we established a closed femoral fracture rat model. We evaluated the levels of MPO, IL-1β and CINC-1 in fractured tissue homogenate, and we measured the levels of IL-6 and IL-10, the biomarkers for systemic inflammatory response, in the rat sera. In clinical part of the study, we collected blood from patients with isolated closed femoral fractures and evaluated PMN-related chemoattractants (IL-8, IL-1β and G-CSF) and the number of peripheral PMN. We further evaluated the level of mitochondrial DNA in the local haematoma of fracture and the circulating plasma of the patients with fracture. In the animal model of closed femoral fracture, we found a significant recruitment of PMN to the local tissue after fracture, which correlates with the elevated MPO level. We also showed that the concentration of IL-1β and CINC-1 in local tissue is significantly increased and might be responsible for the PMN recruitment. Recruitment of PMN to the local tissue was accompanied with a significant increase in the systemic levels of IL-6 and IL-10 in serum. In the patients with closed femoral fracture, we observed an increase in the number of peripheral PMN and PMN-related chemoattractants, including IL-8, IL-1β and G-CSF. The level of mitochondrial DNA in the local haematoma of fracture and the circulating plasma of patients were significantly higher compared to the healthy volunteers. Our data suggest that fracture released mitochondrial DNA into the local haematoma of fracture, which recruited the PMN into the local tissue via chemokines (IL-1β and CINC-1), then increased the numbers of peripheral PMN and SIRS related cytokines in serum (IL-6 and IL-10). This might be the mechanism of the fracture-initiated SIRS.

Bone intramedullary reaming grafts the fracture site with CD146+ skeletal progenitors and downmodulates the inflammatory environment

INTRODUCTION

Femoral shaft fractures generally occur in young adults following a high-energy trauma and are prone to delayed union/non-union. Novel therapies to stimulate bone regeneration will have to mimic some of the aspects of the biology of fracture healing; however, which are these aspects is unclear. Locked intramedullary nailing is the current treatment of choice for the stabilisation of femur shaft fractures, and it is associated with accelerated healing and increased union rates. These benefits were partially attributed to the reaming procedure, which, regardless of significantly destroying the haematoma, stimulates the healing response. To better understand how reaming influences healing, we evaluated the viability of the nucleated cell fraction and the frequency of CD146⁺ skeletal progenitors, which contain multipotent cells, in the post-reaming haematoma. We also screened the concentrations of inflammatory mediators and growth factors in the fracture site after reaming compared with those in the original haematoma.

METHODS

Pre- and post-reaming haematomas were percutaneously aspirated from the fracture site of 15 patients with closed femoral shaft fractures. Cellular viability and the percentage of CD146+ progenitors were analysed by flow cytometry. The concentrations of cytokines and growth factors were determined by ELISA.

RESULTS

AnnexinV/Pi analysis showed that the viability of the total nucleated cell fraction was decreased in the post-reaming haematoma. However, the procedure increased the percentage of CD146+ skeletal progenitors in the fracture site. Analysis of cytokines and growth factors in supernatants showed a decreased concentration of the inflammatory mediators IL-6, CCL-4, and MCP-1, along with an increase of anti-inflammatory IL-10, and the growth factors bFGF and PDGF-AB.

CONCLUSION

These findings support the view that the positive effects of reaming on fracture healing might result from mechanically grafting the fracture site with a population of skeletal progenitors that contain multipotent cells; transitioning the signalling environment to a less inflammatory state, and enhancing the availability of specific osteogenic and angiogenic factors. A better understanding of the requisite stimuli for optimal bone repair, considering the disturbances made by orthopaedic treatments, will be determinant for the development of innovative treatments for bone repair.

Functional block of IL-17 cytokine promotes bone healing by augmenting FOXO1 and ATF4 activity in cortical bone defect model

We determine the effect of interleukin (IL)-17 neutralizing antibody on new bone regeneration. Anti-IL-17 antibody promoted new bone regeneration in cortical bone defect model by augmenting FOXO1 and ATF4 activity thereby decreasing oxidative stress. Our study demonstrates the bone healing and regeneration potential of neutralizing IL-17antibody in osteoporotic fractures.

INTRODUCTION

The immune system plays important role in the fracture healing process. However, fracture healing is prolonged in disorders associated with systemic inflammation. Fracture healing is decelerated in osteoporosis, condition linked with systemic inflammation. Bone regeneration therapies like recombinant human BMP2 are associated with serious side effects. Studies have been carried out where agents like denosumab and infliximab enhance bone regeneration in osteoporotic conditions. Our previous studies show the osteoprotective and immunoprotective effects of neutralizing IL-17 antibody. Here, we determine the effect of IL-17 neutralizing antibody on new bone regeneration and compare its efficacy with known osteoporotic therapies.

METHODS

For the study, female BALB/c mice were ovariectomized or sham operated and left for a month followed by a 0.6-mm drill-hole injury in femur mid-diaphysis. The treatment was commenced next day onwards with anti-IL-17, anti-RANKL (Receptor activator of nuclear factor kappa-B ligand), parathyroid hormone (PTH), or alendronate for a period of 3, 10, or 21 days. Animals were then autopsied, and femur bones were dissected out for micro-CT scanning, confocal microscopy, and gene and protein expression studies.

RESULTS

Micro-CT analysis showed that anti-IL-17 antibody promoted bone healing at days 10 and 21, and the healing effect observed was significantly better than Ovx, anti-RANKL antibody, and ALN, and equal to PTH. Anti-IL-17 also enhanced new bone regeneration as assessed by calcein-labeling studies. Additionally, anti-IL-17 therapy enhanced expression of osteogenic markers and decreased oxidative stress at the injury site.

CONCLUSION

Overall, our study demonstrates bone healing and regeneration potential of neutralizing IL-17 antibody in osteoporotic fractures.

Effects of Sclerostin Antibody on the Healing of Femoral Fractures in Ovariectomised Rats

The inhibition of sclerostin by the systemic administration of a monoclonal antibody (Scl-Ab) significantly increased bone mass and strength in fractured bones in animal models and non-fractured bones in ovariectomised (OVX) rats. In this study, the effects of Scl-Ab on healing were examined in a closed fracture model in OVX rats. Sixty Sprague-Dawley rats underwent an ovariectomy or a sham operation at 4 months of age, and a closed fracture of the right femur was performed 3 months later. Subcutaneous injections with Scl-Ab (25 mg/kg) or saline were then administered on day 1 after the fracture and twice a week for 8 weeks (n = 20 per group), at which time the fractured femurs were harvested for micro-computed tomography analysis, four-point bending mechanical testing and histomorphometric analysis to examine bone mass, bone strength and dynamic bone formation at the fracture site. The angiogenesis at the fracture site was also examined. Bone marrow stem cells were also isolated from the fractured bone to perform a colony-forming unit (CFU) assay and an alkaline phosphatase-positive (ALP(+)) CFU assay. OVX rats treated with Scl-Ab for 8 weeks had significantly increased bone mineral density and relative bone volume compared with OVX rats treated with saline. Similarly, maximum loading, energy to maximum load and stiffness in Scl-Ab-treated OVX rats were significantly higher than those in saline controls. The mineral apposition rate (MAR), mineralising surface (MS/BS) and bone formation rate (BFR/BS) were also significantly increased in Scl-Ab-treated group compared with the saline-treated group in OVX rats. Furthermore, the Scl-Ab-treated group had more CFUs and ALP(+) CFUs than the saline-treated group in OVX rats. No significant difference in angiogenesis at the fracture site was found between the groups. Our study demonstrated that Scl-Ab helped to increase bone mass, bone strength and bone formation at the fracture site in a closed femoral fracture model in OVX rats. Bone marrow stem cells in OVX rats injected with Scl-Ab also had increased CFUs and ALP(+) CFUs.

[Dynamics of the cytokines profile in pentoxiphylline application under conditions of polytrauma]

The impact of pentoxiphylline on the cytokines profile while the polytrauma simulation in rats was studied in experiment. There was established, that application of pentoxiphylline in polytrauma prophylaxes the significant rising of proinflammatory cytokines and lowering of the anti-inflammatory cytokines level.

[Effects of Tongmai decoction on the perioperative changes of plasma TNF-alpha and IL-6 in patients with femoral fractures]

OBJECTIVE

To explore the effects of Tongmai decoction on the perioperative changes of serum concentrations of tumor necrosis factor alpha (TNF-alpha) and interleukin (IL)-6 in patients with femoral fractures, and conform the effectiveness of Tongmai decoction on inflammatory factors in patients with femoral fractures, providing the theoretical evidence for the clinical use of Tongmai decoction.

METHODS

From October 2007 to May 2009, 60 patients with closed traumatic femoral fractures were selected according to the inclusion criterias and exclusion criterias. All the patients were randomly divided into three groups (group A, group B and group C). Twenty patients in group A (Tpanax Notoginseng pill group), 13 patients were male and 7 patients were female; ranging in age from 20 to 45 years, averaged 32.0 years; the disease course ranged from 2.0 to 26.0 h, with an average of 9.5 h. Twenty patients in group B (Tpanax Notoginseng pills and Lornoxicam injection group),12 patients were male and 8 patients were female; ranging in age from 23 to 42 years, averaged 31.0 years; the disease course ranged from 3.5 to 25.0 h, with an average of 13.6 h. Twenty patients in group C (Tpanax Notoginseng pill, Lornoxicam injection and Tongmai decoction group), 14 patients were male and 6 patients were female; ranging in age from 21 to 44 years, averaged 31.5 years; the disease course ranged from 4.6 to 29.0 h, with an average of 13.3 h. Among all the patients, 42 patients with fractures were fixed with femoral intramedullary nailing, and other 18 patients with femoral locking plate fixation. The patients in group A took Tpanax Notoginseng pills orally, 4 g each time and twice daily; the patients in group B took Tpanax Notoginseng pills orally as group A, and at the same time received intramuscular injection of Lornoxicam, 8 mg each time and once daily; the patients in group C took Tpanax Notoginseng pills orally and received intramuscular injection of Lornoxicam as group B, and at the same time took Tongmai decoction (R ) orally, 200 ml each time and twice daily. The above medications were administered to the three groups on the second day after admission to hospital. Peripheral blood samples were taken for determination of pro-inflammatory cytokines of TNF-alpha and IL-6 in blood serum on the 2nd and 6th days before operation and on the 8th and 13th days after operation. And all the patients were evaluated liver and kidney function at the 2nd and 7th days after admission. Analysis of variance and least significant difference-test were done with the help of SPSS 17.0 statistic software.

RESULTS

The differences among three groups of TNF-alpha and IL-6 in blood serum at the 2nd day after admission and 2 days after operation had no statistical significance (P > 0.05). The TNF-alpha and IL-6 levels among 3 groups had statistical differences at the 7th day after admission and at the 7th day after operation (P < 0.05, P < 0.01). There were significant differences of TNF-alpha and IL-6 levels between the 7th day after admission and the 2nd day after admission, the 7th day after operation and the 2nd day after admission (P < 0.01). There were also significant differences of TNF-alpha and IL-6 levels between group C compared with group A and B at the 7th day after admission and the 7th day after operation(P < 0.05, P < 0.01).

CONCLUSION

The serum concentrations of TNF-alpha and IL-6 level significantly increased in perioperative period. The results indicate that the Tongmai decoction may play an important role in inhibiting the release of TNF-alpha and IL-6 into the blood stream and decreasing the incunabula complication at early traumatic stage.

Systemic inflammation and remote organ damage following bilateral femur fracture requires Toll-like receptor 4

Extensive soft tissue injury and bone fracture are significant contributors to the initial systemic inflammatory response in multiply injured patients. Systemic inflammation can lead to organ dysfunction remote from the site of traumatic injury. The mechanisms underlying the recognition of peripheral injury and the subsequent activation of the immune response are unknown. Toll-like receptors (TLRs) recognize microbial products but also may recognize danger signals released from damaged tissues. Here we report that peripheral tissue trauma initiates systemic inflammation and remote organ dysfunction. Moreover, this systemic response to a sterile local injury requires toll-like receptor 4 (TLR4). Compared with wild-type (C3H/HeOuJ) mice, TLR4 mutant (C3H/HeJ) mice demonstrated reduced systemic and hepatic inflammatory responses to bilateral femur fracture. Trauma-induced nuclear factor (NF)-κB activation in the liver required functional TLR4 signaling. CD14−/− mice failed to demonstrate protection from fracture-induced systemic inflammation and hepatocellular injury. Therefore, our results also argue against a contribution of intestine-derived LPS to this process. These findings identify a critical role for TLR4 in the rapid recognition and response pathway to severe traumatic injury. Application of these findings in an evolutionary context suggests that multicellular organisms have evolved to use the same pattern recognition receptor for surviving traumatic and infectious challenges.

Neutrophil Priming for Elastase Release in Adult Blunt Trauma Patients

BACKGROUND

Elevated plasma elastase levels have been reported following major trauma and isolated femoral fracture. Reamed femoral nailing has been shown to further increase plasma elastase levels. The aim of this study was to investigate polymorphonuclear neutrophil (PMN) priming for degranulation following major trauma and isolated long-bone/pelvis fracture by assessing the ability of PMN to release elastase in vitro in response to a stimulus.

METHODS

We further analyzed PMN surface expression of the integrins CD11b and CD18 as markers of PMN activation. Ten major trauma (Injury Severity Score>or=18) patients and 12 patients with isolated long-bone/pelvis fracture were included in the study. Patients in the isolated fracture group were further stratified into reamed nail and external-fixation groups following surgery.

RESULTS

A significant increase in the capacity of PMN to release elastase was seen following major trauma, but not in isolated fracture patients. Surgery did not further alter PMN elastase release. CD11b and CD18 expression was essentially unaltered in all groups.

CONCLUSIONS

PMN is primed for increased degranulation following major trauma but not following isolated long-bone/pelvis fracture. Accumulation of primed, hyperactive PMN into tissues can lead to severe tissue damage and thus multiple organ failure.

[Research on the expression of some immune markers after reamed and unreamed femoral nailing]

OBJECTIVE

To investigate on the expression of some cytokines and other immunity makers right after the operation, the effect of femoral nailing on systemic immunity and sought to differentiate any differences between reamed and unreamed IMN.

METHODS

Fifty-nine patients presenting with acute femoral fractured including 55 male and 4 female, 32.1 years old on average, are divided into 2 group depend on ISS. All patients were treated by close reduction and intramedullary nail for fixation. In group 1, 23 reamed and 23 unreamed; in group 2, 7 reamed and 6 unreamed. Venous blood samples were taken at 24 hr pre-operationally, and 1 hr, 24 hr, 48 hr post operationally. Serum TNF, IL-6, IL-8, IL-10 were measured by enzyme-linked immunosorbent assay. CRP was measured by protein assay apparatus. We also collected venous samples from 22 healthy uninjured volunteers, which formed control group.

RESULTS

All immune marks were elevated post operation, for IL-6, IL-8, IL-10, this elevation began at 1 hr after operation, reached to the peak at 24 hr, and then down but never to the normal at 48 hr. For TNF and CRP, the level were raised at 24 hr, and then fallen at 48 hr. All mediators were raised significantly above the control group (< 0.05). Between reamed and unreamed patients both in group 1 and group 2, Although there was a trend towards higher levels of TNF, IL-6, IL-8, IL-10 and CRP in RFN than in the URFN, no significant difference was found except that there was a greater release of serum IL-10 in RFN than in URFN at 24 hr post operation (P = 0.047). Two patients have become SIRS, but the markers have shown no significant difference with those that have no SIRS symptoms.

CONCLUSIONS

To the patient not injured severely, using IMN for treatment will make the inflammatory mediators re-released on higher level than normal, which will be balanced by immunity itself soon, so IMN won't make any damage severely. And no significant difference were found between reamed and unreamed nail. But the changing of IL-10 show us that after IMN, especially the reamed nailing, the level of anti-inflammatory mediators will show the difference more apparently between RFN and URFN while the patient got injured more severely. Under this condition, the RFN will aggravate the restrain of immunity.

Healing of bone fractures of rat shin and some immunological indices during magnetic laser therapy and osteosynthesis by the ilizarov method

The effect of magnetic and laser therapy on healing of bone fractures and blood levels of T and B lymphocytes was studied in rats during osteosynthesis by the Ilizarov method. Laser therapy induced changes in cells attesting to stimulation of reparative processes and normalization of immunological parameters.

Biochemical changes after trauma and skeletal surgery of the lower extremity: quantification of the operative burden

OBJECTIVE

To quantify changes in variables of inflammation, coagulation, and fibrinolysis in blunt trauma patients with lower extremity fractures who underwent different types of surgical procedures.

DESIGN

Prospective, cohort study.

SETTING

Level I university trauma center.

PATIENTS

We allocated 83 blunt trauma patients in stable condition and 22 patients eligible for elective hip replacement to four treatment groups.

INTERVENTIONS

In 34 multiply traumatized patients with femoral fracture (group PTFF) and in 28 patients with an isolated femoral fracture (group IFF), primary unreamed intramedullary nailing for stabilization of the femoral shaft fracture was performed. In 22 patients, an elective uncemented total hip arthroplasty (group THA) was inserted for osteoarthritis, and in 21 control patients, an isolated ankle fracture (group AF) was acutely stabilized.

MEASUREMENTS AND MAIN RESULTS

From serially sampled central venous blood, the perioperative concentrations of interleukin (IL)-6, of tumor necrosis factor-alpha, of prothrombin fragments 1 + 2, and of D-dimer cross-linked fibrin degradation products were evaluated. Intramedullary instrumentation for an isolated femur fracture caused a significant perioperative increase in the concentrations of IL-6 (preoperative IL-6, 52 +/- 12 pg/mL; IL-6 30 mins postinsertion, 78 +/- 14 pg/mL; p = .02). This increase was comparable with group THA (preoperative IL-6, 46 +/- 16 pg/mL; IL-6 30 mins postinsertion, 67 +/- 11 pg/mL; p = .03). A positive correlation occurred between both groups (r = .83, p < .0004). Multiple trauma patients demonstrated significantly (p = .0002) higher IL-6 concentrations than all other groups throughout the study period and showed a significant increase after femoral nailing (preoperative IL-6, 570 +/- 21 pg/mL; IL-6 30 mins postinsertion, 690 +/- 24 pg/mL; p = .003), whereas no perioperative change was seen in group AF. The highest IL-6 increases were associated with a longer ventilation time (group PTFF) and a longer period of positive fluid balances (groups PTFF, IFF, THA). The coagulatory variables demonstrated similar perioperative increases in groups IFF and THA, but not in groups PTFF and AF. The IL-6 concentrations and the prothrombin fragments 1 + 2 concentrations correlated between groups THA and IFF at 30 mins and at 1 hr after surgery (r2 = .64, p < .02). In all patients the clinical variables were stable perioperatively.

CONCLUSIONS

Major surgery of the lower extremity causes changes to the inflammatory, fibrinolytic, and coagulatory cascades in patients with stable cardiopulmonary function. The inflammatory response induced by femoral nailing is biochemically comparable to that induced by uncemented total hip arthroplasty. In multiple trauma patients, increases, which occurred in addition to those induced by the initial trauma, were measured. Definitive primary femoral stabilization by intramedullary nailing imposes an additional burden to the patient with blunt trauma. A careful preoperative investigation is required to evaluate whether primary definitive stabilization can be performed safely.

Interleukin-10 release and monocyte human leukocyte antigen-DR expression during femoral nailing

This study determined the effect of femoral nailing on the expression of monocyte Class II antigens and interleukin-10 release and sought to differentiate any differences in the release of these elements of immune reactivity in patients undergoing reamed and unreamed nailing. Thirty-two patients presenting with an acute femoral fracture were studied. In 15 patients, the femoral fracture was stabilized with a reamed technique and in 17 patients with an unreamed technique. Venous blood samples were taken at presentation, at anesthetic induction, immediately after nail insertion, and subsequently at 1, 4, and 24 hours and at 3, 5, and 7 days after surgery. Serum interleukin-10 was measured by an enzyme-linked immunosorbent assay, and monocyte human leukocyte antigen-DR expression was quantified by flow cytometry. Serum interleukin-10 release and human leukocyte antigen-DR expression on monocytes showed a clear response to the nailing procedure. The group of patients undergoing a reamed femoral nailing procedure showed significantly higher interleukin-10 release and a significant depression in the expression of human leukocyte antigen-DR on monocytes compared with those whose nail had been inserted unreamed. One patient in the reamed femoral nailing group died of adult respiratory distress syndrome 3 days after injury. Reamed intramedullary nailing appears to be associated with greater impairment of immune reactivity than is the unreamed nailing technique.

Priming of neutrophil [Ca2+]i signaling and oxidative burst by human fracture fluids

BACKGROUND

Patients with major fracture/soft-tissue injuries are at risk for adult respiratory distress syndrome after secondary infection. Fracture fluids (FF) are rich in neutrophil (PMN) -specific chemokines such as interleukin-8. PMN respond to both interleukin-8 and bacterial stimuli with calcium ([Ca2+]i) fluxes, which can initiate respiratory burst (RB). We hypothesize that small amounts of FF entering the circulation could exaggerate PMN [Ca2+]i and RB responses, potentially increasing the risk of adult respiratory distress syndrome.

METHODS

FF were obtained from 10 patients at open fixation of the femur 2 to 5 days postinjury. Volunteer PMN were isolated and loaded with fura dye. PMN were preincubated either in 30% autologous plasma (AP)/70% buffer, or in 5% FF/25% AP/70% buffer. Cells were resuspended in buffer with 1,2,3-dihydrorhodamine and stimulated with low-dose n-formyl-methionyl-leucyl-phenylalanine (fMLP). [Ca2+]i was assayed by fura fluorescence at 505 nm after excitation at 340/380 nm. RB was assessed by 1,2,3-dihydrorhodamine fluorescence at 530 nm after 488 nm excitation.

RESULTS

PMN basal [Ca2+]i was higher after FF incubation than AP incubation (94+/-12 vs. 61+/-9 nmol/L, p = 0.0002). Peak [Ca2+]i response to fMLP was 475+/-47 nmol/L after FF but only 356+/-22 nmol/L after AP (p = 0.01). Two hundred seconds after fMLP, [Ca2+]i remained higher after FF (172+/-17 vs. 145+/-9 nmol/L, p = 0.04). Basal RB was slightly higher after FF than AP (13.4+/-0.3 vs. 11.3+/-0.3 units, p = 0.051) as was the maximal rate of extracellular oxidant release (1.10+/-0.17 vs. 0.76+/-0.16 units/s, p = 0.004) and total oxidant production (42.5+/-0.8 vs. 31.7+/-0.8 units, p = 0.006).

CONCLUSION

Small amounts of FF in plasma can exaggerate PMN [Ca2+]i flux and RB responses to subsequent bacterial stimuli. These findings are consistent with the hypothesis that release of FF into the circulation primes PMN and, thus, may predispose to adult respiratory distress syndrome. Such PMN priming events might have important implications for both the operative and medical management of patients with major fractures.

Femur fracture induces site-specific changes in T-cell immunity

BACKGROUND

Trauma is associated with altered host defense and susceptibility to infection, in part due to cytokine dysregulation and altered T-cell immunity. The gut-associated lymphoid tissue (GALT) provides a defense against infection and contributes to the process of mucosal healing by T-cell activation and cytokine production.

OBJECTIVE

To determine whether femur fracture induces alterations in Peyer's patch and splenic T-cell phenotype, proliferative response, and cytokine expression following traumatic injury.

METHODS

Mice underwent femur fracture or sham procedure and, 48 h later, lymphocytes were isolated from spleen and Peyer's patches. Lymphocytes were cultured, and lipopolysaccharide (10 microg/ml) was added in some cultures. Cells and supernatant were harvested at 48 h. Proliferation was analyzed by [3H]thymidine, and interleukin-10 (IL-10) protein was measured by ELISA in the culture supernatant. T-cell phenotype was determined by flow cytometry.

RESULTS

Femur fracture induced a significant increase in proliferative response in Peyer's patch immunocytes. In contrast, no significant differences were identified in splenocyte proliferative response 48 h after femur fracture injury. Femur fracture induced a significant decrease in IL-10 protein expression of both splenocytes and Peyer's patches. Femur fracture also induced a significant increase in the fraction of CD3(+), CD4(+), and T-cell receptor-alpha beta Peyer's patch immunocytes, whereas splenocytes demonstrated no significant phenotypic change.

CONCLUSION

Femur fracture is associated with significant alterations in Peyer's patch but not splenic T-cell phenotype and proliferative response early (48 h) after injury. Changes in the GALT immune response may contribute to intestinal mucosal dysfunction and increased susceptibility to gut-derived sepsis after traumatic injury.

Trauma decreases leucine enkephalin hydrolysis in human plasma

Plasma hydrolysis of leucine enkephalin was evaluated, together with several cellular immune parameters, in a homogeneous group of human subjects who had undergone severe trauma (proximal femur fracture); data obtained were compared with those obtained in an age-matched control group. In the experimental group, immediately after hospitalization, substrate hydrolysis was reduced with respect both to the control subjects and the same patients 4 weeks after the trauma. Chromatographic separation of the enzymes active on leu-enkephalin showed that the reduction of substrate hydrolysis is mainly attributable to the decrease in the activity of enkephalin-degrading enzymes, principally of aminopeptidases, per se, whereas the role of the low-molecular-weight plasma inhibitors is only minor. In the same subjects, several of the immunological parameters measured underwent modifications that may be considered stress related. However, the absence of a quantitative relationship between reduction in hydrolysis and modifications of immune parameters does not support the hypothesis of a direct relationship between these two sets of data.

Altered T cell cytokine production following mechanical trauma

BACKGROUND

Cell mediated immunity is suppressed following traumatic injury. The Objective is to determine whether there is a shift from T helper type 1 (TH1) to TH2 cell cytokine production following mechanical trauma in a rat model.

METHODS

Male Sprague-Dawley rats were anesthetized and subjected to bilateral femur fractures or sham injury. Spleens were removed 3 days later. T cell proliferation and cytokine production were stimulated by culturing spleen cells with the T cell mitogen concanavalin A (con A). Interleukin-2 (IL-2), interferon-gamma (IFN-gamma), IL-10 and IL-4 concentrations were measured in spleen cell supernatants using enzyme linked immunosorbent assays.

RESULTS

Con A-induced spleen cell proliferation was decreased in traumatized rats compared to controls (p < 0.05). Spleen cell supernatant concentrations of the TH1 cytokines IL-2 and IFN-gamma were decreased in the trauma group (p < 0.05). Supernatant concentrations of the TH2 cytokine IL-10 were also decreased in traumatized rats (p < 0.01). The IL-4 concentrations were below the detection limit (< 15 pg/mL) in all cell supernatants.

CONCLUSIONS

Mechanical tissue injury leads to generalized suppression of T helper cell cytokine production rather than a shift from TH1 to TH2 cell activity. Post-trauma cellular immunosuppression is not mediated via excess IL-10 production by TH2 cells.

Secretory phospholipase A2 cleavage of intravasated bone marrow primes human neutrophils

BACKGROUND

Recent clinical reports suggest that early femoral intramedullary rod (IMR) fixation in patients with multiple injuries increases the risk of adult respiratory distress syndrome (ARDS). We have shown that lipid-mediated neutrophil (PMN) priming and elevated circulating levels of secretory phospholipase A2 (sPLA2) within the first 24 hours after injury correlate with the development of ARDS. We thus hypothesized that circulating lipid products, generated by sPLA2 cleavage of intravasated bone marrow, prime PMNs for enhanced superoxide anion (O2-) production.

METHODS

Isolated PMNs from healthy volunteers were incubated for 5 minutes with buffer or sPLA2-lysed bone marrow (100 U/mL) collected from trauma patients. After formyl-methionyleucylphenylalanine (fMLP) activation, O2- production was quantified by the superoxide dismutase-inhibitable reduction of cytochrome c. Blood samples were also drawn from five injured patients before and 24 hours after femoral IMR fixation. PMNs were isolated and assessed for in vivo priming.

RESULTS

PMNs incubated with sPLA2-lysed bone marrow were primed for more than 3.5 times greater fMLP-induced O2- production. Furthermore, in patients with femoral fractures, PMN O2- release in response to fMLP after IMR fixation was more than 2.5 times higher than before fixation.

CONCLUSION

Collectively, the findings suggest that bone marrow released from acute fracture sites may become a lipid substrate for the elevated sPLA2 levels found in injured patients. The resultant priming of PMNs may thus render the injured patient at risk for ARDS. Although clearly hypothetical at present, we submit that these observations warrant further investigation because of their clinical implications.

Suppression of natural killer cell activity in patients with fracture/soft tissue injury

BACKGROUND

Natural killer cells (NKCs) participate in "innate" cell-mediated immunity. Fracture/soft tissue injuries are cytokine rich and may influence cell-mediated immunity.

OBJECTIVE

To study the effects of fracture cytokines on NKC function.

DESIGN

A case-control study.

SETTING

A level I trauma center and laboratory in a university medical center.

PARTICIPANTS

Patients requiring open fracture fixation and healthy volunteers.

INTERVENTIONS

Fracture supernatants and peripheral plasma were collected during open fracture fixation. Volunteer mononuclear cells were used as effector (NKC) sources. Mononuclear cells were preincubated with fracture supernatants, paired peripheral plasma, or normal plasma under various conditions.

MAIN OUTCOME MEASURES

Natural killer cell lysis of K562 target cells was assessed by chromium 51 release.

RESULTS

Fracture supernatants suppressed NKC function more rapidly than peripheral plasma. Fracture supernatants from 1 to 4 days after injury were most suppressive. Inactivation of complement and reactive oxygen species failed to restore lysis. Neutralizing antibodies to interleukin 4 and interleukin 10 further suppressed lysis. Antibodies to transforming growth factor beta1 failed to restore lysis. The addition of interferon gamma did not restore lysis but the addition of interleukin 12 did.

CONCLUSIONS

Fracture supernatants and peripheral plasma from patients with fractures suppress NKCs. The responsible mediators may be concentrated in fracture/soft tissue injuries. Responses to manipulation of the cytokine environment suggest that fracture cytokines may impair cooperation between NKCs and accessory cells.

The impact of femur fracture with associated soft tissue injury on immune function and intestinal permeability

Alterations in intestinal permeability and immune function were investigated in a murine femur fracture (FFx) model. We postulated that soft tissue injury associated with closed FFx (crush injury) would result in greater immunosuppression that open FFx (surgical division). AKR mice were randomized to four groups (Normal, Sham, Open FFx, Closed FFx) and studied at 24 and 96 h post-injury. Immune function was assessed by splenocyte blastogenic response and class-specific immunoglobulin production. Intestinal permeability was assessed by measurement of whole blood fluorometry after gavage administration of fluorescein-dextran (FITC-dextran). Closed FFx is associated with increased splenocyte blastogenesis and increased immunoglobulin production at 24 h post-injury. This immunostimulatory response was associated with altered intestinal permeability early after injury (FITC-dextran:.185 +/- .070 Closed FFx vs. .069 +/- .011 Normal, p = .06). Immunosuppression was evident at 96 h post-injury in the closed FFx group, documented by significant reductions in splenocyte blastogenesis to all mitogens studied. The Open FFx group did not demonstrate any reduction in splenocyte blastogenesis at 96 h post-injury. These data suggest that the soft tissue injury associated with Closed FFx is associated with significant immunosuppression and altered gastrointestinal permeability, which may adversely affect the host by increasing the relative risk of post-trauma infection.

Emphysematous gastritis in an immunocompromised host

Emphysematous gastritis is a rare, often lethal condition of gastric mural inflammation and gaseous dissection. Infection with gas-forming organisms is the most frequently cited cause. In all previously reported patients, the clinical presentation was dramatic. We report on an immunocompromised host who had a surprisingly subtle clinical presentation.

Activation of Kupffer cells in vivo following femur fracture

OBJECTIVE

To test the hypothesis that Kupffer cells are activated after blunt femur fracture leading to altered hepatic oxygen (O2) consumption.

DESIGN

Prospective randomized experimental trials.

SETTING

Laboratory.

MATERIALS AND METHODS

Male Sprague-Dawley rats underwent closed femur fracture with associated soft-tissue injury. Control animals received only anesthesia. After 30 minutes and 2 hours, livers were perfused and fixed. Tissue was processed for scanning and transmission electron microscopy. In separate experiments, hepatic O2 consumption was measured in isolated perfused livers 2 and 48 hours after femur fracture using a Clark-type electrode. Oxygen consumption was calculated from the influent-effluent concentration difference, flow rate, and liver weight.

RESULTS

In femur-fractured animals, scanning electron microscopy revealed alterations in Kupffer cell surface characteristics, including increases in cell volume and complex foldings and extensions of the plasma membrane. Transmission electron microscopy showed internal vacuolization and dark-staining granule formation. The changes were more pronounced 2 hours after femur fracture. Hepatic O2 consumption increased significantly at both 2 and 48 hours after femur fracture. Morphologic and functional activation of Kupffer cells were not seen in control animals.

CONCLUSION

In vivo ultrastructural evidence shows Kupffer cell activation after closed femur fracture. This activation is associated with increased hepatic O2 consumption, which is present at 2 hours and persists 48 hours following injury. The results suggest that Kupffer cell activation may be related to the acute-phase response following trauma.

Glucocorticoid receptor blockade reverses postinjury macrophage suppression

OBJECTIVES

To study the effects of the stress-induced surge of endogenous glucocorticoids on macrophage function and the role of inhibiting glucocorticoids with a receptor antagonist, mifepristone (RU 486).

DESIGN

One hundred thirty female Swiss-Webster mice were randomly assigned to either injury by femur fracture or uninjured anesthesia control in this intervention study.

SETTING

A university-based surgical laboratory and animal facility.

INTERVENTION

Injured mice were randomized to receive either the glucocorticoid receptor antagonist mifepristone (10 mg/kg by oral gavage) or its vehicle. Mifepristone or its vehicle were given either 2 hours before or 2 hours after the injury.

MAIN OUTCOME MEASURES

Peritoneal macrophages were harvested 24 hours after the injury. Macrophages were assayed for the stimulated (phorbol myristate acetate, 1 microgram/mL) production of superoxide anion, secretion of interleukin-6, tumor necrosis factor alpha, and prostaglandin E2 in response to endotoxin (lipopolysaccharide at 10 micrograms/mL) and killing of Candida albicans.

RESULTS

Pretreatment with mifepristone significantly prevented or reduced suppression of several macrophage functions following injury, including superoxide production and C albicans killing. Treatment after the injury preserved only C albicans. Mifepristone failed to block the increased secretion of prostaglandin E2 after injury.

CONCLUSION

Pretreatment with mifepristone before an injury prevented suppression of several macrophage functions. Further studies are required on the effects of glucocorticoid inhibition on other aspects of the immune and metabolic responses to injury to define the potential clinical applications of mifepristone trauma.

Effect of stress and trauma on bacterial translocation from the gut

Previously, we established that bacteria contained within the gut can cross the GI mucosal barrier and spread systemically, a process termed bacterial translocation. Three models were used to extend this work: cold exposure (up to 16 hr at 4 degrees C), a nontissue injury stress model; femoral fracture-amputation, a trauma model; and thermal injury (30% third-degree burn), a trauma model with retained necrotic tissue. CD-1 mice either with a normal GI microflora or who were monoassociated with Escherichia coli C-25 were subjected to sham or actual stress or trauma. The animals were sacrificed at various times postinsult and the ceca, mesenteric lymph nodes (MLN), spleens, and livers were quantitatively cultured. Neither the incidence nor the magnitude of bacterial translocation was increased in the cold-exposed animals compared to control mice. The incidence of bacterial translocation to the systemic organs was higher in the animals with a normal flora receiving femoral fracture amputation (11%) (P less than 0.02) than in animals receiving a thermal injury (1%) or sham-injured control mice (0%). In contrast, the incidence of translocation to the liver or spleen was higher in burned mice monoassociated with E. coli C-25 (60%) (P less than 0.01) than in E. coli monoassociated mice sustaining femoral fracture amputation (17%). Stress alone (cold exposure) does not promote bacterial translocation; however, trauma, especially in combination with retained necrotic tissue, promotes bacterial translocation. Thus bacteria colonizing the gut can invade systemic organs after trauma, especially when the normal ecology of the gut flora has been disrupted.

[Immunological shifts in trauma]

The level of immunoglobulins, complement and properdin, data of leukograms were studied in 40 patients with closed fractures of bones with noncomplicated and complicated (by a purulent infection) course of the posttraumatic period. The authors have established variants of changes of these parameters, their correlation with the adaptation reactions of the organism and severity of the trauma.

High arginine levels in intravenous hyperalimentation abrogate post-traumatic immune suppression

Trauma victims often suffer immune system failure. Oral arginine has strong immune-enhancing properties. The metabolic, hormonal, and immune effects of increasing concentrations of arginine as part of post-trauma intravenous hyperalimentation (IVH) were studied. Groups of 11-14 rats, 275-350 g, underwent jugular vein catheterization and bilateral closed femoral fractures under anesthesia. IVH was started immediately postinjury at a rate of 0.8-1 ml/100 g body wt/hr and continued for 5 days. Twenty percent dextrose and three different amino acid mixtures were given as follows: (A) FreII (1.55 g ARG/1); (B) FreIII (4.05 g ARG/1); (C) modified FreIII (7.9 g ARG/1). All rats lost weight over the 5-day postinjury period; however, rats in groups B and C lost significantly less weight than rats in group A (-3.4 +/- 0.8% of initial body weight and -3.6 +/- 0.9% vs -6.1 +/- 1.2%, P less than 0.05). Rats in group A had negative cumulative nitrogen balance, while those in groups B and C were in highly positive balance. No significant difference in body weight change or nitrogen balance was noted between groups B and C. Trauma-induced thymic involution as assessed by thymic weight and lymphocyte content was greatest in group A, which received the lowest amount of arginine, and was linearly abrogated by increasing the amount of arginine administered (A less than B less than C). Thymocyte immune responsiveness increased with the amount of arginine given as assessed by mitogenesis in response to Con A (stimulation index: A--151.3 +/- 28.8 vs B--243.6 +/- 29.2, P less than 0.01 vs C--321.8 +/- 22.3, P less than 0.001 vs A and P less than 0.02 vs B) and PHA (A--65.0 +/- 14.3 vs B--67.7 +/- 15.3, NS, vs C--117 +/- 14.0, P less than 0.005 vs A and B).(ABSTRACT TRUNCATED AT 250 WORDS)