Mouse models to study wound closure and topical treatment of infected wounds in healing-impaired and normal healing hosts

Full-thickness wounds were made on the backs of wound healing-impaired diabetic mice and their normally healing litter mates. The wounds were then inoculated with 10(4) colony-forming units of Pseudomonas aeruginosa. In both cases, the inoculum increased rapidly to between 10(9) and 10(10) colony-forming units/wound area. The infection caused a significant decrease in wound closure in the normally healing mice. In the wound healing-impaired diabetic mice, infection increased the size of the wound area over 100% by day 21. The wound became filled with inflammatory cells and serous fluid, and the mice lost significant amounts of weight, an additional sign of severe, ongoing infection. Early antimicrobial treatment of infected wounds in diabetic mice (1 hour after wounding and microbial inoculation) reversed the increase in wound size area, improved wound closure, and reduced to a significant degree the weight loss observed in untreated control mice. Delay in treatment for as little as 8 hours significantly reduces the efficacy of antimicrobial treatment. These models can be used to study the effects of infection as well as to determine the efficacy of topical antimicrobial and/or wound healing-enhancing substances on these wounds in both normally healing and healing-impaired hosts.

Effects of a restrictive blood transfusion policy on outcomes in children with burn injury

A restrictive blood transfusion policy decreases blood utilization and improves outcomes in critically ill adults, but the impact of a restrictive blood transfusion policy in critically ill children is unclear. The study purpose was to compare the effects of a restrictive with a traditional blood transfusion policy in children with major burn injury. A retrospective review of all blood transfusions administered in a pediatric burn center during a 5-year period was conducted. Children in the traditional group (January 1, 2000, to June 30, 2002), were transfused at a hemoglobin level of less than 10 g/dl. Children in the restrictive group (January 1, 2003, to June 30, 2005, 6 months after the adoption of a restrictive protocol) were transfused at a hemoglobin level of less than 7 g/dl. Patient groups were compared for demographics, ventilator requirements, blood transfusion number, transfusion costs, and outcomes. Of the 1140 patients studied, 266 (24%) received a total of 2577 units of blood. There was no difference in age, TBSA burn, sex, inhalation injury, or mortality between groups. Patients in the traditional group received more blood than the restrictive group (12.3 +/- 1.8 vs 7.2 +/- 1.2 units/patient, P < .001). The mean cost of blood per patient was $2781 for the traditional group and $1489 for the restrictive group. A restrictive transfusion policy in children with burn injury decreases the amount of blood transfused, does not adversely impact patient outcome, and results in significant cost savings to the institution.

Hypothalamic-pituitary-adrenal axis response to sustained stress after major burn injury in children

The hypothalamic-pituitary-adrenal (HPA) axis is responsible for stress response after injury, yet its function after severe burn injury in children is unclear. The purpose of this study was to define the effects of burn injury on the HPA axis and to evaluate the utility of total serum cortisol in measuring adrenal function in children with major burns in the 2 months after injury. Children ages 0 to 17 years who were admitted within 72 hours to our pediatric burn center with 20% TBSA or greater full-thickness burns were eligible for the study. Serum total cortisol, adrenocorticotropic hormone (ACTH), dehydroepiandrosterone, vasopressin, Pediatric Risk of Mortality (PRISM) score, serum albumin level, and electrolytes were obtained on admission and weekly for 8 weeks. An ACTH stimulation test (250 microg for children >2 years, 125 microg for children < or =2 years) was administered weekly at 8:00 am. Total serum cortisol was measured before and 60 minutes after the administration of ACTH. Twenty-five children with mean age 7.6 +/- 1.1 years and TBSA burn 41.8 +/- 3.8% were enrolled in the study. Baseline total serum cortisol was 12.4 +/- 0.7 microg/dl in the 8 weeks after injury and increased to 24.4 +/- 0.8 microg/dl after the administration of ACTH. Cortisol level did not correlate with PRISM score, albumin, vasopressin, ACTH, or mortality. Although the adrenal response to acute and chronic stress is intact after severe burn injury, the ACTH/adrenal feedback loop is disrupted. Random total serum cortisol measurements overestimate adrenal dysfunction; thus, ACTH stimulation testing should be used to assess adrenal function before the administration of exogenous steroids.

End of Life in the Pediatric Burn Patient

Up to 60% of deaths in pediatric intensive care units occur after placing limits upon life-sustaining treatment. Two-thirds of limitations are made on the last day of life. Our aim was to characterize the timing, indications, and implementation of "do not resuscitate" (DNR) orders and the withdrawal of support from children with severe burns. A retrospective evaluation was conducted of all deaths in a pediatric burn unit over a 7-year period. Values are presented as mean +/- SD; two-tailed t-tests and Fisher's exact tests were used for analysis. Of the 29 deaths (total admissions = 1261; 2.3% death rate), 12 were of patients with DNR status. Active withdrawal of support occurred for 15 patients: 10 with DNR orders, 5 without. There was no difference in age, burn size, inhalation injury, etiology of injury, cause of death, intensive care unit days, or ventilator days between DNR patients and non-DNR patients. Of the 12 patients with DNR status, only five had orders indicating no cardiopulmonary resuscitation (CPR), no vasopressors, and no cardioversion. The mean time from DNR to death was 22.9 +/- 49.6 hours (median, 2.75 hours). Patients without DNR orders before death had more CPR attempts (0.8 +/- 0.6 vs. 0.3 +/- 0.6; P < .05). At the time of death, few patients with DNR orders were receiving vasopressors (two patients) or underwent CPR (1 patient). Of the 17 patients without DNR orders, 12 underwent resuscitative efforts: CPR (11), vasopressors (12), or cardioversion (9). No resuscitative efforts were undertaken for four children, two with DNR orders. For the acutely injured child there is a strong tendency to wait until the last possible hours of life to address limitation of life-sustaining measures. Documentation of limitation of care was not previously addressed in nearly a third of cases in which support was actively withdrawn. Once a decision to limit support was made, the majority of children proceeded rapidly to death. Further evaluation of the indications, timing, and implementation of DNR orders for children with severe burns is warranted.

Burn Injury Caused by Motor Vehicle Use and Repair

Despite continued efforts to increase safety, burns associated with motor vehicles have accounted for as much as 10% of all burn admissions. Our objective was to characterize the mechanism of these burn types. We undertook a retrospective review of all patients admitted to a regional burn center from 1997 through 2003. A total of 2745 patients were admitted; 8.0% (n = 220) had automobile-associated injuries. Their mean age was 29.6 +/- 18.1 years, and 83.6% (n = 184) were men. Mean burn size was 14 +/- 15.6% TBSA, 7.5 +/- 15.2% full-thickness. Inhalation injury occurred in 25 patients, and 25 patients had associated nonburn injuries. Mean length of stay was 14.8 +/- 23.6 days. Those patients undergoing procedures (n = 108) had an average of 2.1 operations, with a mean area grafted of 2780 cm. There were two deaths in this group of patients. Hospital charges amounted to 53,200 dollars +/- 78,000 per patient. Automobile burns still account for a significant portion of burn unit admissions. The most severe injuries appear to be from the regular use and maintenance of vehicles. The most common burn injuries are from radiators and carburetors. Simple prevention should be adequate to avoid these injuries. Current efforts appear to have made minimal headway.

Septic Hip Presenting With Dislocation as a Source of Occult Infection in a Burn Patient

An 11-year-old boy was transferred to a regional burn center after sustaining 53% TBSA burns. Initial wound cultures grew multiple organisms. Multiresistant Klebsiella was cultured from the patient's blood. When the patient indicated worsening hip pain, radiographs revealed a spontaneous hip dislocation. Immediate arthrotomy revealed left hip synovial fluid infected with Klebsiella. The patient remained afebrile and was discharged home 6 months after admission.

Instant Cup of Soup: Design Flaws Increase Risk of Burns

Prepackaged soups are a frequent cause of burn injury. We hypothesize that package design increases the risk for burn injury by affecting container stability. All pediatric scald burns caused by soup, between June 1997 and August 2004, were reviewed for burn and patient characteristics. Instant or "ready-to-eat" soups also were purchased. Safety statements and recommendations as to use of the microwave oven were documented. The height and the areas of the base and top were compared to the angle that a container would tip over on to its side. During the study period, 99 admissions and 80 outpatients were treated for burns caused by soup. Although the burn size was small (mean 5% TBSA) 22 patients required grafting. Of 13 different soups, 11 required the addition of hot water, and 2 were prepackaged for eating out of the container. Twelve containers had round bases and were tall and narrow, with one being shorter and rectangular. The measurements that correlated with the ease of tipping over were the base area, top area, and the ratio of height/base area. The most significant contributor to the ease of tipping over was height. Instant soups are packaged in containers that tend to be tall with a narrow base that predisposes them to being knocked over and spilled. Simple redesigning of instant soup packaging with a wider base and shorter height, along with the requirement for warnings about the risks of burns would reduce the frequency of soup burns.

Ketamine: a safe and effective agent for painful procedures in the pediatric burn patient

Ketamine is an effective agent when used for sedation during painful bedside procedures. We developed a ketamine administration protocol for nonanesthesiologists for the purpose of establishing safe monitoring and documentation during ketamine sedation procedures. From June 1, 2002, through June 30, 2003, a total of 522 sedation events using ketamine were performed; 347 of these events were analyzed. Seventeen (4.9%) events contained potentially adverse outcome indicators, 10 (2.9%) of which required intervention. Eight events were airway related and responded to repositioning, supplemental oxygen, or bag-valve-mask ventilation. Two patients had a decrease in blood pressure, which responded to fluid administration. Total doses of ketamine administered were between 6 and 800 mg, for procedures ranging from 1 to 105 minutes, in patients weighing between 3 and 111 kg. The development of a strict protocol ensures the safe administration of ketamine for the pediatric burn patient.

Effects of oxandrolone on outcome measures in the severely burned: a multicenter prospective randomized double-blind trial

Severe burns induce pathophysiologic problems, among them catabolism of lean mass, leading to protracted hospitalization and prolonged recovery. Oxandrolone is an anabolic agent shown to decrease lean mass catabolism and improve wound healing in the severely burned patients. We enrolled 81 adult subjects with burns 20% to 60% TBSA in a multicenter trial testing the effects of oxandrolone on length of hospital stay. Subjects were randomized between oxandrolone 10 mg every 12 hours or placebo. The study was stopped halfway through projected enrollment because of a significant difference between groups found on planned interim analysis. We found that length of stay was shorter in the oxandrolone group (31.6 +/- 3.1 days) than placebo (43.3 +/- 5.3 days; P < .05). This difference strengthened when deaths were excluded and hospital stay was indexed to burn size (1.24 +/- 0.15 days/% TBSA burned vs 0.87 +/- 0.05 days/% TBSA burned, P < .05). We conclude that treatment using oxandrolone should be considered for use in the severely burned while hepatic transaminases are monitored.

Effect of blood transfusion on outcome after major burn injury: a multicenter study

OBJECTIVE

To delineate blood transfusion practices and outcomes in patients with major burn injury.

CONTEXT

Patients with major burn injury frequently require multiple blood transfusions; however, the effect of blood transfusion after major burn injury has had limited study.

DESIGN

Multicenter retrospective cohort analysis.

SETTING

Regional burn centers throughout the United States and Canada.

PATIENT POPULATION

Patients admitted to a participating burn center from January 1 through December 31, 2002, with acute burn injuries of >or=20% total body surface area.

OUTCOMES MEASURED

Outcome measurements included mortality, number of infections, length of stay, units of blood transfused in and out of the operating room, number of operations, and anticoagulant use.

RESULTS

A total of 21 burn centers contributed data on 666 patients; 79% of patients survived and received a mean of 14 units of packed red blood cells during their hospitalization. Mortality was related to patient age, total body surface area burn, inhalation injury, number of units of blood transfused outside the operating room, and total number of transfusions. The number of infections per patient increased with each unit of blood transfused (odds ratio, 1.13; p<.001). Patients on anticoagulation during hospitalization received more blood than patients not on anticoagulation (16.3+/-1.5 vs. 12.3+/-1.5, p<.001).

CONCLUSIONS

The number of transfusions received was associated with mortality and infectious episodes in patients with major burns even after factoring for indices of burn severity. The utilization of blood products in the treatment of major burn injury should be reserved for patients with a demonstrated physiologic need.

Continuous nebulized albuterol attenuates acute lung injury in an ovine model of combined burn and smoke inhalation

OBJECTIVE

Albuterol, due to its bronchodilatory and anti-inflammatory effects, is given via continuous nebulization in children with severe asthma. Combined burn and smoke inhalation injury frequently results in acute lung injury due to a combination of airway obstruction and inflammation. We hypothesized that albuterol administered via continuous nebulization would mitigate acute lung injury after smoke inhalation injury and burn.

DESIGN

Randomized prospective animal model.

SUBJECTS

Twenty adult female sheep (mean weight, 33.1+/-0.9 kg).

INTERVENTIONS

Adult ewes were subjected to a 40% body surface area third-degree flame burn and smoke inhalation injury after tracheostomy. Sheep were allocated to a) sham group, b) saline continuous nebulization group, c) 20 mg of albuterol continuous nebulization group, or d) 40 mg of albuterol continuous nebulization group (n=5 animals per group). All groups received intravenous lactated Ringer's solution at 4 mL.kg-1.%burn(-1).24 hrs-1 for resuscitation and were equally mechanically ventilated throughout the 48-hr study period. Pulmonary and cardiac function, lung lymph flow, bronchial obstruction score, and wet/dry lung weights were recorded.

RESULTS

Compared with saline and control groups, the albuterol groups had lower pause and peak inspiratory pressures, decreased pulmonary transvascular fluid flux, a significantly higher Pao2/Fio2 ratio, and decreased shunt fraction at 48 hrs postinjury. The wet-to-dry lung weight ratio and bronchial obstruction scores were lower for sheep receiving albuterol.

CONCLUSIONS

Continuous nebulization of albuterol improves pulmonary function via improved airway clearance and decreased fluid flux in a combined burn/smoke inhalation injury model.

CD14-dependent modulation of NF-κB alternative splicing in the lung after burn injury

Nuclear factor kappa-B (NF-kappaB), a key downstream player of the LPS signaling pathway, has been shown to undergo alternative splicing in in vitro studies. In this study, we examined the effect of injury and the role of CD14 on NF-kappaB alternative splicing using a murine burn model. CD14 knockout and respective wild-type mice were sacrificed after 18% total body surface area burn. RT-PCR and subsequent sequencing analysis revealed that injury induced multiple novel splicing variants of relA, relB, and NF-kappaB2 in the lungs of CD14 knockout but not wild-type mice. These novel variants resulted either from exon skipping, alternative usage of splicing signals, or intron retention. All but one variant resulted in a frameshift leading to premature termination of translation. These splicing variants encoded for proteins that lacked the domains essential for NF-kappaB transcription factor functions. Two NF-kappaB2 variants acquired only minor changes in their C-terminus that might affect their post-translational cleavage into active isoforms. These results suggest that alternative splicing may be one of the mechanisms by which NF-kappaB activity in the lungs can be regulated after injury. Furthermore, the CD14-mediated LPS signaling pathway may play a role in the regulation of NF-kappaB alternative splicing in the lungs after injury.

Norepinephrine Modulates the Inflammatory and Proliferative Phases of Wound Healing

BACKGROUND

Injury results in the massive release of norepinephrine (NE) into the peripheral circulation. Recent investigations have demonstrated functional adrenoreceptors on the cellular mediators of cutaneous wound healing and NE-induced phenotypic alterations in immune cells have been demonstrated in vitro. Despite this, there is little description of how NE might alter the phases of wound healing in vivo. The purpose of this study was to compare cutaneous wound healing in norepinephrine-intact and norepinephrine-depleted mice.

METHODS

Norepinephrine-depleted (NED) mice were generated by chemical axotomy with 6-hydroxydopamine and compared with norepinephrine-intact (NEI) animals (n = 6-12 per group, per time point). Using an excisional wound model, neutrophil recruitment was measured by myeloperoxidase assay. Macrophage recruitment and angiogenesis were measured by immunohistochemistry and re-epithelialization was determined histologically. The development of incisional wound disruption strength was determined over time. Finally, macrophage scavenger function was assessed by an in vitro latex bead phagocytosis assay.

RESULTS

Wounds from NEI mice demonstrated greater neutrophil infiltration than NED wounds (24, 72 hours; p < 0.05). Wound macrophage recruitment was initially higher in NEI animals (24 hours, p < 0.05), but was eventually surpassed by that of NED animals (120 hours, p < 0.05). Angiogenesis was decreased while re-epithelialization was accelerated in NEI animals (p < 0.05). Wound disruption strength and macrophage scavenger function were unaltered between NED and NEI mice.

CONCLUSIONS

Norepinephrine modulates the inflammatory and proliferative phases of wound healing in a temporally defined, cell-specific manner. By increasing recruitment of innate immune cells and expediting wound closure, norepinephrine appears to play a protective role in defense against infection.

Impact of tight glycemic control in severely burned children

BACKGROUND

Control of hyperglycemia has been shown to decrease mortality in critically ill adults, but the benefits of strict glucose control have not been established in children. Since January 2002, our pediatric burn center has adopted a policy of 'intensive' insulin therapy to achieve blood glucose levels 90 to 120 mg/dL. The purpose of this study was to examine the impact of this practice on patient outcomes.

METHODS

We reviewed the records of children with > or =30% total body surface area (TBSA) burn injury admitted to our regional pediatric burn center from July 1, 2000 to June 31, 2003. Patients were grouped into 'conventional insulin therapy' for the 2000 to 2001 period (n = 31) and into 'intensive insulin therapy' for the 2002 to 2003 period (n = 33). The efficacy of glucose control, infection rates, and patient survival were compared for the two therapies.

RESULTS

The demographic characteristics and injury severity were similar between the conventional and intensive insulin therapy groups. Children receiving intensive insulin therapy had glucose levels of 90 to 120 mg/dL more consistently than those in the conventional insulin therapy group. There was a significant decrease in urinary tract infections among intensive insulin therapy patients. TBSA burn, percent full-thickness burn, and Pediatric Risk of Mortality scores were negatively related to survival; intensive insulin therapy was positively associated with survival.

CONCLUSION

Intensive insulin therapy to maintain normoglycemia in severely burned children can be safely and effectively implemented in the burn unit. This therapy seems to lower infection rates and improve survival. Intensive insulin therapy should be considered for children with severe burn injuries.

Comparison of Measured Resting Energy Expenditure Versus Predictive Equations in Pediatric Burn Patients

Many equations have been developed to estimate resting energy expenditure (REE) in thermally injured patients. A consensus has not been reached on the accuracy of these equations in children. The purpose of our study was to compare three predictive equations: Harris Benedict x 2 multiplier (HB x 2), Mayes (MG), and the WorId Health Organization x 2 multiplier (WHO x 2) with measured resting energy expenditure x I.3 multiplier (MREE x 1.3) in pediatric burn patients. MREE was measured by open-circuit indirect calorimetry in 10 burned children (6 boys, 4 girls) aged 2 to 10 years with TBSA burn ranges from 35% to 97%. MREE x 1.3 was compared with values obtained by HB x 2, MG, and WHO x 2 predictive equations. When comparing MREE x 1.3 with all three equations, significant differences were found when compared with HB x 2 and MG, but there were no significant difference between MREE x 1.3 vs WHO x 2. The HB x 2 and MG equations overpredicted MREE x 1.3 by 29% and 19%, respectively. Many predictive equations have been developed to predict energy expenditure in burns, but their accuracy in predicting MREE x 1.3 is variable. A larger study comparing/contrasting predictive equations and resting energy expenditure measured by indirect calorimetry is needed to improve the prediction of energy needs in burned children.

Downregulation of NF-kappaB activity associated with alteration in proliferative response in the spleen after burn injury

Alterations in proliferation status and cellular composition of immune organs are among key events in the modulation of immune function after burn injury. Nuclear factor (NF)-kappaB is a transcription factor that plays a pivotal role in the response to injury as well as immune cell differentiation and proliferation. In this study, we investigated the effects of burn injury on the activity of NF-kappaB and its association with cellular proliferation in the spleen. Western analysis of whole spleen tissues of mice after 18% burn injury revealed a marked reduction in nuclear NF-kappaB rel A protein expression 3 to 21 days after injury when there was an increase in proliferative activity in the red pulp of the spleen after injury as indicated by an increase in proliferating cell nuclear antigen (PCNA). In the splenic B cells, however, the down-regulation of NF-kappaB rel A was associated with decreased PCNA expression as well as IkappaBalpha and phosphorylated IkappaBalpha. In contrast, no significant change in NF-kappaB rel A or PCNA expression was observed for splenic T cells. These data suggest that there is a differential regulation of NF-kappaB and proliferative activity in the splenic cell subsets after burn injury. Furthermore, the regulation of NF-kappaB may be linked to the proliferative changes seen in the spleen after burn injury.

CD14- and toll-like receptor 4-dependent regulation of c-Fos, c-Jun and c-Jun phosphorylation in the adrenal gland after burn injury

OBJECTIVES

Although the pathophysiology of the adrenocortical response after injury has been described, alterations in the molecular profile (e.g. transcription factors) of the adrenal gland itself are not well understood. The regulation of c-Fos, c-Jun, and c-Jun phosphorylation in the adrenal gland after burn injury was investigated in this study. In addition, since burn injury is often associated with lipopolysaccharide (LPS)-mediated sepsis, we examined the involvement of the LPS signaling pathway in the regulation of these transcription factors utilizing CD14 knockout and C3H/HeJ (encoding defective toll-like receptor 4) mice.

METHODS

Adrenal glands harvested after an 18% total body surface area burn were subjected to RT-PCR and Western blot analyses of c-Jun and c-Fos.

RESULTS

There was a rapid induction of c-Jun and c-Fos expression (mRNA and protein), and c-Jun serine phosphorylation. The induction of c-Jun and its phosphorylation after injury was greater in CD14 knockout and C3H/HeJ mice compared to their respective controls. A similar pattern was observed in the c-Fos regulation.

CONCLUSIONS

These data suggest that c-Fos and c-Jun are activated in the adrenal gland in response to burn injury. In addition, an LPS-mediated signaling pathway may influence the regulation of these transcription factors after injury.

Temperature threshold for burn injury: an oximeter safety study

Pulse oximeters have become essential devices for evaluating and monitoring patient oxygenation. The probe emits a small amount of heat into the skin in the process of signal detection. Regulations set by the Food and Drug Administration currently limit the maximum allowable temperature of an oximeter probe to 41 degrees C. As a result of the prolonged exposure of extremities to these devices, we sought to determine the actual temperature threshold for burn injury in patients. Eighteen patients undergoing surgery for removal of redundant skin (abdominoplasty, breast reduction) consented to the application of a temperature-controlled custom probe with four light-emitting diodes that had temperatures set randomly at the expected threshold for burn injury (42.5 degrees C, 43 degrees C, 43.5 degrees C, and 44 degrees C). The probe was left in place for 8 hours (or less if significant pain was noted). The sites covered by the probes were then checked for signs of injury. On the next day, the redundant skin was removed as a scheduled procedure, and histopathology was performed to detect the extent of burn injury. The study was approved by the local institutional research board. Two patients were excluded because of technical problems with the probe, one of whom had the probe turned off because of pain. The only observed sign of injury was either erythema or a superficial blister that was usually unobservable or slightly red at operation. These subtle signs of a burn were noted in one patient at 43 degrees C, four at 43.5 degrees C, and nine at 44 degrees C. No burns were noted in two patients. Minimal or no signs of injury frequently were noted by histopathology. Pulse oximeter probes are safe up to a temperature of 43 degrees C for at least 8 hours in well-perfused skin. Above that temperature, there is a risk of burn injury. Performing temperature threshold tests in redundant skin that is planned for excision is a potential method for testing the safety of devices or materials.

CD14-dependent Modulation of Transcriptional Activities of Endogenous Retroviruses in the Lung after Injury

Lipopolysaccharide (LPS) plays a central role in the pathogenesis of distant organs after burn. Recent studies demonstrated the regulation of mouse endogenous retroviruses (MuERVs) in several organs after burn. In this study, the role of CD14, a LPS receptor, in burn-mediated regulation of MuERV expression in the lung was investigated. CD14 knockout (KO) and wild type (WT) mice were subjected to burn followed by RT-PCR analysis of alterations in the MuERV expression in the lung 1 day after injury. Even without injury, CD14 KO mice had a unique profile of MuERV expression compared to WT. Three bands (Lung-1, Lung-2, and Lung-3) in CD14 KO were downregulated after injury. Lung-2 and Lung-3 transcripts were almost identical to 2 previously described defective env transcripts of MuERVs, respectively. The Lung-1-1 transcript was a double spliced message generated by the env and a set of novel splicing signals, whereas the Lung-1-2 transcript was a defective env transcript. Only the Lung-1-1 transcript had a significant ORF capable of encoding a gag-pol fusion polypeptide. Putative proviral sequences of Lung-1-1 and Lung-1-2 transcripts were mapped to chromosomes 4 and 11, respectively. The results from this study suggest that the absence of CD14 expression in CD14 KO mice contributes to the transcriptional regulation of MuERVs in the lung after injury.

CD14-dependent alterations in c-Jun expression in the liver after burn injury

BACKGROUND

Burn injury-triggered activation of lipopolysaccharide signaling via the CD14 pathway alters the expression of a variety of downstream genes contributing to pathogenic changes in distant organs. The regulation of CD14 and its role in the immediate-early response of c-Jun in the liver after burn injury were investigated in this study.

MATERIALS AND METHODS

An incidental identification of the differential induction of CD14 mRNA after an approximately 18% TBSA burn injury in mice was confirmed by RT-PCR and immunohistochemical analyses of CD14 expression. Subsequently, CD14's role in the immediate-early regulation of c-Jun expression in the liver after injury was examined by Western blot analysis using CD14 knockout (KO) mice.

RESULTS

RT-PCR analysis demonstrated a rapid and transient induction of CD14 mRNA in the liver and lungs of mice after injury. Immunohistochemical analysis revealed a peak induction of CD14 reactivity in cells appearing to be Kupffer cells at day 1 after injury. Furthermore, an augmented and delayed induction of c-Jun mRNA was observed in the liver of CD14 KO mice after injury compared to wild-type controls. The induction of phosphorylated (serine 63 or serine 73) forms of c-Jun after injury was lower in the livers of CD14 KO mice than that in WT controls.

CONCLUSIONS

This study provides evidence that injury elicits CD14 induction as well as hyperphosphorylation of the c-Jun N-terminus activation domain and that CD14 is involved in the modulation of c-Jun's transactivation potential via phosphorylation, which may be associated with hepatic pathogenesis after injury.