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Am J Physiol Lung Cell Mol Physiol 292: L984-L991, 2007. First published January 5, 2007; doi:10.1152/ajplung.00248.2006
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Inhibition of JNK activation prolongs survival after smoke inhalation from fires

Olga L. Syrkina,1,2 Deborah A. Quinn,1 Walter Jung,2 Bin Ouyang,1 and Charles A. Hales1,2

1Pulmonary and Critical Care Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, and 2Shriners Burn Hospital, Boston, Massachusetts

Submitted 28 June 2006 ; accepted in final form 28 December 2006


   ABSTRACT
TOP
 ABSTRACT
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
Initial injury from smoke inhalation is mainly to the trachea and bronchi and is characterized by mucosal hyperemia and increased microvascular permeability, exfoliation of epithelial lining, mucous secretion, mucous plugging, and an acute inflammatory cell influx. In this study, we explore the role of the c-Jun N-terminal protein kinase (JNK) pathway in smoke inhalation lung injury using a rat model of exposure to smoke from burning cotton. Male Sprague-Dawley rats were exposed to smoke from burning cotton for 15 min, and 1 h after injury a JNK inhibitor (SP-600125) or vehicle was injected. We measured neutrophil influx, cytokine release, percent of apoptotic cells, airway plugging, and survival. Administration of a JNK inhibitor 1 h after smoke inhalation decreased airway apoptosis, mucous plugging, influx of inflammatory cells, and the release of cytokines and significantly prolonged animal survival (P < 0.05). These in vivo data show that the JNK pathway plays a critical role in smoke-induced lung injury and offer an attractive therapeutic approach for this injury.

fire victims; apoptosis; c-Jun NH2-terminal kinase inhibitor

IN THE UNITED STATES in 2002, nearly 3,400 people died in fires, according to the Federal Emergency Management Agency U.S. Fire Administration. Smoke inhalation injury is a serious threat to victims of house fires, explosions, and other disasters involving fire and smoke. This type of injury alone can be lethal as shown in the Cocoanut Grove fire, in which 492 people died, most without burns (31). In the Rhode Island nightclub fire, 95 people died (out of 350 victims and survivors of this tragedy), and 187 people were treated for smoke inhalation lung injury and burns (7). Autopsy series from fire victims show sloughed mucosal cells and a collection of proteinaceous debris obstructing the airways (24). There are multiple case reports in adults and children of airway obstruction due to these tracheobronchial casts (24). The airway microenvironment is significantly altered by smoke inhalation with lung parenchymal damage occurring because of surfactant denaturation, loss of endothelial and epithelial barrier functions, and influx of inflammatory cells (8, 9, 11, 29). Previous reports (28) have shown that airway epithelial cells, if exposed to various extracellular stimuli, have the capacity to produce a variety of biologically active molecules and elicit specific biological responses through activation of mitogen-activated protein kinase (MAPK) cascades.

Apoptosis or programmed cell death frequently increases during injury and inflammation in many types of tissues. The plasma membrane remains intact as the disintegrating organelles are bound within vesicles, which prevents leakage of toxic intracellular components. Phagocytic cells then dispose of the dead cells or cellular fragments. There exist distinct signaling pathways that lead to apoptosis. Apoptosis is well studied in many tissues and commonly involves the stress-activated protein kinases including the c-Jun NH2-terminal kinase (JNK). The major target of JNK is the activator protein-1 (AP-1) transcription factor. AP-1 translocates to the nucleus and increases expression of proteases that cleave intracellular organelles and lead to cell death (3, 4, 10, 16, 21, 26, 27). There are now pharmacological inhibitors of the JNK pathway, including the JNK Inhibitor II (SP-600125; Calbiochem, La Jolla, CA) (1, 11).

In this study, we used our established small-animal model of smoke inhalation injury (30) to test the hypothesis that smoke inhalation induces airway apoptosis through activation of the JNK pathway and that treatment with a JNK inhibitor would diminish airway apoptosis and airway plugging and prolong animal survival.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
This study was approved by the Massachusetts General Hospital Subcommittee on Research Animal Care and conducted in compliance with guidelines of United States Department of Agriculture Animal Welfare Act, Public Health Service Policy on Humane Care and Use of Laboratory Animals.

Materials. The JNK inhibitor II (SP-600125) was purchased from Calbiochem (San Diego, CA) and was injected 1 h after injury. The JNK inhibitor was dissolved in dimethyl sulfoxide (DMSO) (Sigma-Aldrich).

Experimental animals. Sprague-Dawley viral-free rats, all in the growing phase and weighing between 200 and 250 g, were obtained from Charles River Laboratories (Wilmington, MA).

Smoke inhalation. Smoke inhalation was administered as previously described (30). Animals were orally intubated with a polyethylene catheter under general anesthesia with intraperitoneal ketamine (50 mg/kg) and diazepam (5 mg/kg) while spontaneously breathing room air and then placed in the smoke chamber for 15 min. Following 15 min of smoke inhalation, animals were allowed to recover. Animals were extubated ~10 min after smoke. Intubation lasted for ~30 min. One hour after smoke exposure, some animals received an injection of JNK inhibitor or DMSO (as a vehicle) subcutaneously.

Experimental design. Animals were randomly assigned to one of four groups: controls (Control), smoke inhalation alone (Smoke), smoke inhalation followed by DMSO (vehicle) injection (Smoke + DMSO), or smoke inhalation followed by 30 mg/kg JNK inhibitor injection (Smoke + JNK Inh.). The dose was chosen based on previous in vivo studies that showed 30 mg/kg inhibited JNK activity (38, 40). Four hours after exposure, the animals were anesthetized and killed through exsanguination. The lungs where removed en bloc. The right lung was used for bronchial lavage for total and differential cell count and cytokine measurement. The left lung was processed for immunohistochemistry.

Western blot analysis. For determination of JNK and poly(ADP-ribose) polymerase (PARP) protein expression, Western blot analysis was performed with PARP antibody and JNK antibodies (Santa Cruz Biotechnology, Santa Cruz, CA, and Cell Signaling Technology, Beverly, MA). Blots were developed by enhanced chemiluminescence (NEN Life Science Products, Boston, MA).

Lung histology and immunohistochemistry. We used the TdT-mediated dUTP nick end labeling (TUNEL) assay (TdT-FragEL DNA fragmentation detection kit, Calbiochem), or ApopTag TdT Enzyme (Chemicon International, Temecula, CA) and Anti-PARP p85 Fragment antibody (Promega, Madison, WI) staining of lung tissue to detect apoptosis. The percent of TUNEL-positive cells per total cell count in each experimental condition were calculated. Values were means ± SD of three random fields (at least 100 cells per field counted). The same method was used for airway epithelial cells in the main bronchi and epithelial cells in the lung parenchyma.

Assessment of mucous plugging. Paraffin-embedded samples were sectioned at 4 µm and stained with Alcian blue (AB) at pH 2.5 and periodic acid-Schiff (PAS) for the localization of acidic and neutral mucin distribution in the airway epithelium of control rats (anesthetized and intubated for 30 min while spontaneously breathing room air without smoke exposure) and in rats with smoke injury (anesthetized, intubated, and exposed to smoke for 10 min). Both control rats and smoke-injured rats were allowed to recover and were killed 4 h after exposure. Intubation lasted ~30 min in both groups. For quantitation of airway obstruction, all histological slides of the left lung were randomly sorted and masked before observation. Each slide was systematically scanned using x4 objective magnification, and for each cross-sectioned airway, a score of 0–100% was made as an estimate of the degree of luminal obstruction for each cross-sectioned airway present. A mean obstruction score was determined for each animal and then for each group.

Pathology scoring. The pathological changes were compared using a modification of a previously described scoring system for pathological changes after smoke inhalation (7). Briefly, we examined five fields (2 peripheral and 3 central) for five injurious variables on each slide. Injurious variables included 1) airway epithelial shedding, 2) airway epithelial edema, 3) increased cellularity in the airway and parenchymal tissues, 4) increased peribronchial and perivascular cuff area, and 5) alveolar atelectasis. The total lung injury score was calculated as the sum of each variable (0 for none or normal to 3 for severe).

Statistical analysis. Analyses were performed using Statview 4.5 (Abacus Concepts, Berkeley, CA). Measurement of pulmonary hemodynamics over time was compared by repeated-measures ANOVA followed by multiple comparisons by Scheffé's test. Significance was set at P < 0.05. All values were expressed as means ± SE. Survival among treatment groups was compared using Mantel-Cox log-rank test.


   RESULTS
TOP
 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 GRANTS
 REFERENCES
 
Smoke inhalation induced airway cell apoptosis via JNK activation. To measure JNK activation in airway epithelial cells, we gently removed the airway epithelial cells from the trachea and major bronchi by scraping. To collect sufficient amounts of protein, we used eight rats at each time point for control animals and six animals from each time point for smoke-exposed animals. The lysates were pooled at each time point. We then performed Western blot analysis of total JNK and phospho-JNK (Fig. 1). The level of JNK activity, as shown by the ratio of phospho-JNK-to-total JNK, was increased by 2.1- and 2.8-fold 2 and 4 h after smoke injury in the airways and remained elevated for up to 24 h compared with control animals (Fig. 1, A and B). The ratio of the four time points for smoke-exposed animals was significantly greater than for the four time points for control animals (Control 0.8 ± 0.1 vs. Smoke 1.5 ± 0.1, n = 4 time points per group; P < 0.01). There was no detectable activation of JNK in the parenchyma (Fig. 1, C and D). Immunohistochemical staining for phospho-JNK (Fig. 2) confirmed that smoke activated the JNK signaling pathway in the airways but not the parenchyma.


Figure 1
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  		Fig. 1. Activation of JNK I (54 kDa) and JNK II (46 kDa), the 2 major isoforms of JNK in airway epithelial cells. There was marked activation of JNK in airway epithelium but not in the parenchyma. A: Western blot analysis of phospho-JNK (p-JNK) and total JNK. Airway epithelial cells were removed from airways by gentle scraping and the protein lysates from the animals at each time point were pooled. Smoke inhalation caused a large upregulation of phospho-JNK, the activated form of JNK, 1 h after smoke exposure, which remains elevated for up to 24 h compared with intubated but nonsmoked control. B: quantitation of Western blots. JNK I and II activation were expressed as the ratio of total phospho-JNK-to-JNK of the pooled samples in smoke-exposed animals (n = 5 per time point) and control animals (n = 8 per time point). C: Western blot analysis of phospho-JNK and JNK in lung parenchyma. D: quantitation of Western blot. JNK and phospho-JNK when expressed as the ratio of total phospho-JNK-to-JNK showed no change compared with control animals (n = 5 per group).

 

Figure 2
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  		Fig. 2. Histochemical staining for phospho-JNK in lung tissue. Smoke exposure caused expression of phospho-JNK (brown color) in airway epithelial cells. The brown color indicates phospho-JNK-positive cells. The arrows point to the phospho-JNK-positive cells (magnification x 1,000). In the lung parenchyma, there were only sparsely stained cells, and we did not find any difference between Control and Smoke groups (magnification x400).

 
To determine the degree of apoptosis in airway epithelial cells and lung parenchyma, we used TUNEL staining. The percent of apoptotic cells was significantly higher after smoke exposure (Table 1 and Fig. 3). There was a more marked increase in apoptosis in the airway cells in the proximal airways compared with the distal airways. We confirmed apoptosis with another marker of apoptosis, the antibody to poly(ADP-ribose) polymerase PARP p85, which is specific for apoptosis in the airway epithelial cells (Table 1 and Fig. 4A) and the lung parenchyma (Fig. 4A). The degree of apoptosis was significantly higher in proximal than in distal bronchi. We also performed Western blot analysis of cleaved PARP, the activated form of PARP in airway epithelial cells (Fig. 4B) and lung parenchyma (Fig. 4C). After smoke inhalation, there was a large increase in cleaved PARP in the airway bronchial epithelial cells (Fig. 4, A and B), another confirmation of apoptosis, but little change in the parenchyma with Smoke, Smoke + DMSO, or Smoke + JNK Inh. (Fig. 4, A and C).


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  		Table 1. TUNEL assay and immunohistochemical detection of PARP p85

 

Figure 3
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  		Fig. 3. Detection of apoptosis in lung tissue. TdT-mediated dUTP nick end labeling (TUNEL) assay showed increased labeling (brown color) of the cells in airway epithelial lining. No apoptosis was detected in airway epithelial cells in control intubated but nonsmoked group. Brown color indicates apoptotic cells (magnification x1,000).

 

Figure 4
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  		Fig. 4. Upregulation of poly(ADP-ribose) polymerase (PARP) in airway epithelial cells and lung tissue. Apoptosis was confirmed with staining for cleaved PARP, another marker of apoptosis. As with TUNEL staining, there was a large increase in apoptosis in the airways but not in the parenchyma. A: PARP p85 staining in the airways of rats after 15 min of smoke exposure. The brown color indicates cells positive for PARP p85 (magnification x400). The arrow points to the positive cells. B: the animals exposed to cotton smoke showed upregulation of cleaved PARP in airway epithelial cells by Western blot analysis. C: PARP p85 staining in the lung parenchyma of rats after 15 min of smoke exposure (magnification x400). There was little upregulation of cleaved PARP in the parenchyma.

 
To explore the role of JNK activation in smoked-induced apoptosis, we gave a subcutaneous injection of the JNK inhibitor 1 h after smoke exposure. The percent of cells positive for apoptosis by TUNEL assay was significantly (P < 0.05) lower in animals treated with the JNK inhibitor than in animals exposed to smoke alone and Smoke + DMSO, the carrier for the JNK inhibitor (Fig. 5), both in the airway epithelial cells and the parenchyma, but these changes were most pronounced in the airway epithelial cells. These findings suggest that the smoke-induced epithelial cell apoptosis was dependent on JNK activation.


Figure 5
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  		Fig. 5. Effect of JNK inhibitor treatment on apoptosis. The animals treated with subcutaneous injection of JNK inhibitor (JNK Inh.) demonstrated a significantly lower percentage of cells staining positive for apoptosis by TUNEL assay. *P < 0.05 vs. Control; #P < 0.05 vs. Smoke (n = 4 or 5 rats per group).

 
JNK inhibitor injection decreased smoke-induced mucous plugging. To explore the effect of JNK inhibition on smoke-induced airway mucous plugging, we used AB and PAS staining as previously described (7). Following smoke exposure, DMSO alone and the JNK inhibitor showed decreased mucous plugging but to a larger degree with the JNK inhibitor than DMSO alone (Fig. 6).


Figure 6
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  		Fig. 6. Staining for mucous plugging in airway epithelium. Mucous plugging was assessed using Alcian blue and periodic acid-Schiff staining. A: staining for plugging in the Control and Smoke groups. The arrow points to a mucous plug. B: the average percentage of airway obstruction with mucous plugging was decreased with both DMSO treatment alone and JNK inhibitor treatment but to a greater extent with the JNK inhibitor. #P < 0.05 vs. Control; *P < 0.05 vs. Smoke alone group.

 
Smoke induced cytokine production and neutrophil influx into BAL. We next examined the degree of airway inflammation in the bronchial lumen by measuring bronchoalveolar lavage (BAL) fluid neutrophil count and cytokine production. BAL harvested from the smoke alone group had markedly increased levels of neutrophils, TNF-{alpha}, IL-6, and macrophage inflammatory protein-2 (MIP-2) compared with controls (Fig. 7). There was a significant reduction in total BAL neutrophils and BAL levels of TNF-{alpha}, IL-6, and MIP-2 in both groups treated with DMSO, the carrier for the JNK inhibitor, and the group treated with the JNK inhibitor compared with smoke alone group.


Figure 7
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  		Fig. 7. Treatment with DMSO and the JNK inhibitor significantly decreased the total number neutrophils, macrophage inflammatory protein-2 (MIP-2), TNF-{alpha}, and IL-6 (n = 5 rats per group). *P < 0.05 vs. Control; #P < 0.05 vs. Smoke alone group.

 
Smoke-induced pulmonary leak was not reduced by inhibition of JNK activity. We used measurement of protein in the BAL and perivascular edema on pathology to determine capillary leak. The JNK inhibitor did not affect pulmonary capillary leak with smoke exposure as determined by BAL protein for Control (0.95 ± 0.36 µg/ml), Smoke (8.7 ± 4.4 µg/ml) vs. Smoke + JNK Inh. (12.1 ± 2.4 µg/ml) (P = 0.43; n = 5 rats per group), or perivascular cuffing score (Control, 0.16 ± 0.12; Smoke, 1.4 ± 0.3, vs. Smoke + JNK Inh., 0.9 ± 0.3; P = 0.11; n = 5 rats per group).

JNK inhibitor injection prolonged animal survival. We explored the role of the JNK inhibitor on animal survival. All animals 1 h after smoke were randomly divided into three groups (n = 10 rats per group): no treatment, injection of the vehicle DMSO, or injection of the JNK inhibitor. Animals were returned to their cages with unrestricted access to food and water. Of the animals in the JNK inhibitor-treated group, 70% survived and gained weight for up to 8 days and 40% survived up to 12 days when they were killed. None of the animals in the no treatment and DMSO-treated group survived longer than 5 days (Fig. 8). The lung histology after smoke inhalation showed periairway interstitial edema, vascular congestion, and hemorrhage with distal sloughing of the bronchiolar epithelium and perivascular edema limited to areas adjacent to airways. Except for an occasional inflammatory cell, there was minimal parenchymal injury in areas not adjacent to airways in the smoke-exposed rats. The damage was worse at 48 h then at 4 h. Treatment with the JNK inhibitor, and to a lesser degree with DMSO, substantially improved airway pathology including airway occlusion (Fig. 9). The parenchymal damage, which was modest to begin with, was also improved by the JNK inhibitor and by DMSO (Fig. 10). We compared the pathological changes using a modified scoring system (7). The pathological score 4 h after smoke inhalation was significantly decreased by use of the JNK inhibitor (Control, 0.6 ± 0.2; Smoke, 8.2 ± 1.1;* Smoke + DMSO, 5.9 ± 0.9;* Smoke + JNK Inh., 3.4 ± 0.9*#; *P < 0.01 vs. Control, #P < 0.001 vs. Smoke). The trends were the same 48 h after smoke inhalation (data not shown), although many animals died, preventing meaningful statistics.


Figure 8
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  		Fig. 8. Effect of JNK inhibitor on animal survival (n = 10 rats per group). Treatment with JNK inhibitor but not with DMSO alone prolonged survival.

 

Figure 9
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  		Fig. 9. Hematoxylin and eosin (H&E) staining of smoke-exposed lungs showed swelling and sloughing of the airway epithelial lining and congestion at 4 h, which was more pronounced at the 48-h time point. The use of JNK inhibitor caused marked improvement in the airway pathology. Histology of the JNK inhibitor-treated group (Smoke + JNK Inh.) was similar to controls (magnification x400), while the Smoke + DMSO group continued to show lung injury. The arrows point to the area of sloughing and swelling of the epithelial lining.

 

Figure 10
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  		Fig. 10. H&E staining of lung parenchyma of control and smoke-exposed animals showed little difference between Smoke and Smoke + DMSO treated group at 4- and 48-h time points, with minor congestion and hemorrhage in the perialveolar space. The JNK inhibitor and, to a lesser extent, DMSO decreased the evidence of injury, which was especially obvious at the 48-h time point (magnification x400).

 

   DISCUSSION
TOP
 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
GRANTS
 REFERENCES
 
Smoke inhalation leads to the formation of obstructive airway debris, which may cause respiratory distress and increased mortality in victims of fire (13, 32, 33). Airway obstruction and smoke-induced lung apoptosis have been shown to occur in animal models with burn and smoke inhalation injuries (38), but the mechanism of the smoke-induced airway damage has remained unclear. We found that smoke inhalation-induced airway apoptosis in our rat model of smoke inhalation injury was dependent on activation of the JNK pathway.

JNK mediated apoptosis has been found to play a role in other types of injury in the lung. We have previously shown that JNK plays a critical role in acute lung injury from high tidal volume mechanical ventilation by mediating lung inflammation and apoptosis in mice (21). In rats, cigarette smoke has also been shown to increase apoptosis and to be associated with JNK activation (18).

To inhibit JNK activity, we used the specific anthrapyrazole JNK inhibitor SP-600125, a reversible ATP competitive inhibitor with greater than 20-fold selectivity vs. other kinases in inhibiting the action but not expression of phospho-JNK (11). At these doses in mice, SP-600125 has been shown to inhibit JNK activation by high tidal volume mechanical ventilation (21) and by adjuvant-induced arthritis (11).

The components of smoke vary according to the source of the smoke. In this study, we used smoke from smoldering cotton. We (12, 15, 30, 38) have previously shown that cotton smoke caused delayed noncardiac edema and, in combination with burn injury, worsened lung inflammation and impaired cardiac function. Cotton smoke contains a high level of acrolein, a common component of house fires (40, 41), which we (15) have previously shown to cause noncardiac pulmonary edema. We hypothesize that it was the acrolein in the cotton smoke that led to JNK activation and airway apoptosis. Acrolein has been found to activate JNK in endothelial and smooth muscles cells (25, 31). In keratinocytes, acrolein activates JNK and causes apoptosis (43).

The difference between apoptotic and necrotic cell death can sometimes be hard to detect. To confirm apoptosis we used two different markers of apoptosis, terminal deoxynucleotidyl transferase (TdT) and PARP p85 (Table 1, Figs. 3 and 4A). PARP has been shown to be activated by oxidant injury and to be an important nuclear factor activator (2). PARP participates in DNA repair. Caspases, which are essential for apoptosis, cleave PARP into two characteristic fragments, 85 kDa and 25 kDa. Anti-PARP 85 has been shown to be specific for the 85-kDa fragment and, therefore, is a marker of apoptosis (6, 34, 36, 43). We used this antibody to confirm smoke-induce apoptosis. The inactivation of PARP by caspase cleavage may contribute to apoptosis (6, 43). This is consistent with findings that inhibition of PARP attenuates smoke-induced lung injury (35). TdT has also been used as a marker of apoptosis in smoke inhalation by other investigators (46). Both markers indicated that smoke induced apoptosis in the bronchial epithelium rather than necrotic cell death (Figs. 3 and 4A). We further confirmed cleavage of full length PARP by Western blot analysis of bronchial epithelial cells (Fig. 4B). We cannot exclude the possibility that necrosis was also present.

Like other investigators (45), we also found that there was an inflammatory component in smoke-induced lung injury. Both DMSO, an antioxidant, and the JNK inhibitor blocked the influx of neutrophils and production of cytokines in the BAL (Fig. 7). However, the most significant finding of the current study was that the treatment with JNK inhibitor 1 h after smoke exposure decreased mortality. Seventy percent of the animals treated with the JNK inhibitor survived for up to 8 days (Fig. 8). Animals who survived were active, eating and gaining weight, and had normal lung pathology. All animals without JNK inhibitor were dead by 5 days. DMSO, the carrier for the JNK inhibitor, alone inhibited neutrophil influx and cytokine production but did not prolong survival or decrease apoptosis. DMSO has been shown not to affect JNK activation (24, 45). These data with the oxygen radical scavenger DMSO suggested that the inflammation induced by smoke involved oxidant stress but that oxidants were not necessary for smoke-induced apoptosis. Acrolein-induced activation of JNK has been shown to not require reactive oxygen species, and this may account for the difference (45).

In contrast to our sheep model of smoke inhalation injury (12), we found that there was an increase in TNF-{alpha} in the BAL fluid in addition to the increases in MIP-2 and IL-6. However, inhibition of this cytokine production alone by DMSO did not prolong survival. Both of these findings suggest that the production of cytokines appears to be a marker of injury but not essential to the pathogenesis of smoke-induced lung injury.

Inhibition of JNK activation appeared to have the greatest effect on the airways. The activation of JNK and the degree of apoptosis was greatest in the airway epithelium with little change in the parenchyma. Use of the JNK inhibitor showed improvement in airway damage and decreased mucous plugging.

DMSO, an antioxidant, has previously been studied in smoke inhalation in a sheep model (3, 17). In sheep, DMSO nebulization every 4 h for 48 h after smoke exposure did not significantly improve survival. DMSO significantly diminished the usual pulmonary lymphatic response to inhalation injury and improved alveolar function, but four out of the six animals died in 72 h. DMSO + heparin, another possible inhibitor of the JNK pathway (14), did improve survival. The role of apoptosis and JNK activation, however, was not explored in that study. The present study showed the beneficial aspects of using a subcutaneous injection of the JNK inhibitor in our rat model of smoke inhalation. JNK inhibitors have undergone large phase I trials and appear safe for humans. Of note, the JNK inhibitor was injected 1 h after smoke inhalation injury, suggesting that this treatment could be used in clinical practice when emergency medical technicians get to the fire victims. The use of JNK inhibitors may provide a new treatment option for victims of smoke inhalation injury.


   GRANTS
TOP
 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
REFERENCES
 
This work was supported by Shriners Burn Institute (Boston, MA) Grant 8620.


   ACKNOWLEDGMENTS
 
We are grateful to John Beagle for excellent technical assistance and to Patricia Della Pelle and Nicole Brousaides for technical help in histological preparation of the lung tissue samples.


   FOOTNOTES
 

Address for reprint requests and other correspondence: O. L. Syrkina, Pulmonary and Critical Care Unit, Massachusetts General Hospital, 55 Fruit St., Bulfinch 148, Boston, MA 02114 (e-mail: osyrkina{at}partners.org)

The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.


   REFERENCES
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 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 

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