Antecedent acute kidney injury worsens subsequent endotoxin-induced lung inflammation in a two-hit mouse model

Acute kidney injury (AKI) contributes greatly to morbidity and mortality in critically ill adults and children. Patients with AKI who subsequently develop lung injury are known to suffer worse outcomes compared with patients with lung injury alone. Isolated experimental kidney ischemia alters distal lung water balance and capillary permeability, but the effects of such an aberration on subsequent lung injury are unknown. We present a clinically relevant two-hit murine model wherein a proximal AKI through bilateral renal ischemia (30 min) is followed by a subsequent acute lung injury (ALI) via intratracheal LPS endotoxin (50 μg at 24 h after surgery). Mice demonstrated AKI by elevation of serum creatinine and renal histopathological damage. Mice with ALI and preexisting AKI had increased lung neutrophilia in bronchoalveolar lavage fluid and by myeloperoxidase activity over Sham-ALI mice. Additionally, lung histopathological damage was greater in ALI mice with preexisting AKI than Sham-ALI mice. There was uniform elevation of monocyte chemoattractant protein-1 in kidney, serum, and lung tissue in animals with both AKI and ALI over those with either injury alone. The additive lung inflammation after ALI with antecedent AKI was abrogated in MCP-1-deficient mice. Taken together, our two-hit model demonstrates that kidney injury may prime the lung for a heightened inflammatory response to subsequent injury and MCP-1 may be involved in this model of kidney-lung cross talk. The model holds clinical relevance for patients at risk of lung injury after ischemic injury to the kidney.     

Knockdown of lung phosphodiesterase 2A attenuates alveolar inflammation and protein leak in a two-hit mouse model of acute lung injury

Phosphodiesterase 2A (PDE2A) is stimulated by cGMP to hydrolyze cAMP, a potent endothelial barrier-protective molecule. We previously found that lung PDE2A contributed to a mouse model of ventilator-induced lung injury (VILI). The purpose of the present study was to determine the contribution of PDE2A in a two-hit mouse model of 1-day intratracheal (IT) LPS followed by 4 h of 20 ml/kg tidal volume ventilation. Compared with IT water controls, LPS alone (3.75 μg/g body wt) increased lung PDE2A mRNA and protein expression by 6 h with a persistent increase in protein through day 4 before decreasing to control levels on days 6 and 10. Similar to the PDE2A time course, the peak in bronchoalveolar lavage (BAL) neutrophils, lactate dehydrogenase (LDH), and protein concentration also occurred on day 4 post-LPS. IT LPS (1 day) and VILI caused a threefold increase in lung PDE2A and inducible nitric oxide synthase (iNOS) and a 24-fold increase in BAL neutrophilia. Compared with a control adenovirus, PDE2A knockdown with an adenovirus expressing a short hairpin RNA administered IT 3 days before LPS/VILI effectively decreased lung PDE2A expression and significantly attenuated BAL neutrophilia, LDH, protein, and chemokine levels. PDE2A knockdown also reduced lung iNOS expression by 53%, increased lung cAMP by nearly twofold, and improved survival from 47 to 100%. We conclude that in a mouse model of LPS/VILI, a synergistic increase in lung PDE2A expression increased lung iNOS and alveolar inflammation and contributed significantly to the ensuing acute lung injury.     

Characterization of a murine model of monocrotaline pyrrole-induced acute lung injury

Background

New animal models of chronic pulmonary hypertension in mice are needed. The injection of monocrotaline is an established model of pulmonary hypertension in rats. The aim of this study was to establish a murine model of pulmonary hypertension by injection of the active metabolite, monocrotaline pyrrole.

Methods

Survival studies, computed tomographic scanning, histology, bronchoalveolar lavage were performed, and arterial blood gases and hemodynamics were measured in animals which received an intravenous injection of different doses of monocrotaline pyrrole.

Results

Monocrotaline pyrrole induced pulmonary hypertension in Sprague Dawley rats. When injected into mice, monocrotaline pyrrole induced dose-dependant mortality in C57Bl6/N and BALB/c mice (dose range 6–15 mg/kg bodyweight). At a dose of 10 mg/kg bodyweight, mice developed a typical early-phase acute lung injury, characterized by lung edema, neutrophil influx, hypoxemia and reduced lung compliance. In the late phase, monocrotaline pyrrole injection resulted in limited lung fibrosis and no obvious pulmonary hypertension.

Conclusion

Monocrotaline and monocrotaline pyrrole pneumotoxicity substantially differs between the animal species.     

Angiogenic growth factors in the pathophysiology of a murine model of acute lung injury

Capillary leakage and alveolar edema are hallmarks of acute lung injury (ALI). Neutrophils and serum macromolecules enter alveoli, promoting inflammation. Vascular endothelial growth factor (VEGF) causes plasma leakage in extrapulmonary vessels. Angiopoietin (Ang)-1 and -4 stabilize vessels, attenuating capillary leakage. We hypothesized that VEGF and Ang-1 and -4 modulate vessel leakage in the lung, contributing to the pathogenesis of ALI. We examined a murine model of lipopolysaccharide (LPS)-induced ALI. C57BL/6 and 129/J mice were studied at baseline and 24, 48, and 96 h after single or multiple doses of aerosolized LPS. Both strains exhibited time- and dose-dependent increases in inflammation and a deterioration of lung mechanics. Bronchoalveolar lavage (BAL) protein levels increased significantly, suggesting capillary leakage. Increased BAL neutrophil and total protein content correlated with time-dependent increased tissue VEGF and decreased Ang-1 and -4 levels, with peak VEGF and minimum Ang-1 and -4 expression after 96 h of LPS challenge. These data suggest that changes in the balance between VEGF and Ang-1 and -4 after LPS exposure may modulate neutrophil influx, protein leakage, and alveolar flooding during early ALI.     

Experimental murine acid aspiration injury is mediated by neutrophils and the alternative complement pathway

Weiser, Martin R., Taine T. V. Pechet, Julian P. Williams,Minghe Ma, Paul S. Frenette, Francis D. Moore, Lester Kobzik, RichardO. Hines, Denisa D. Wagner, Michael C. Carroll, and Herbert B. Hechtman. Experimental murine acid aspiration injury is mediatedby neutrophils and the alternative complement pathway. J. Appl. Physiol. 83(4):1090-1095, 1997.Acid aspiration may result in the development ofthe acute respiratory distress syndrome, an event associated withsignificant morbidity and mortality. Although once attributed to directdistal airway injury, the pulmonary failure after acid aspiration ismore complex and involves an inflammatory injury mediated by complement(C) and polymorphonuclear leukocytes. This study examines the injuriousinflammatory cascades that are activated after acid aspiration. Therole of neutrophils was defined by immunodepletion before aspiration,which reduced injury by 59%. The injury was not modified in either P-or E-selectin-knockout mice, indicating that these adhesion moleculeswere not operative. C activation after aspiration was documented withimmunochemistry by C3 deposition on injured alveolar pneumocytes.Animals in which C activation was inhibited with soluble C receptortype 1 (sCR1) had a 54% reduction in injury, similar to the level ofprotection seen in C3-knockout mice (58%). However C4-knockout micewere not protected from injury, indicating that C activation ismediated by the alternative pathway. Finally, an additive effect ofneutrophils and C was demonstrated whereby neutropenic animals thatwere treated with sCR1 showed an 85% reduction in injury. Thus acidaspiration injury is mediated by neutrophils and the alternative Cpathway.

     

Immunopathology of murine experimental allergic orchitis

Experimental allergic orchitis (EAO) was induced consistently in BALB/c mice by immunization with homologous testicular tissue homogenate emulsified in complete Freund's adjuvant (CFA) providing that the animals had received simultaneously at least 1 microgram of an extract of Bordetella pertussis rich in pertussigen. All animals thus treated developed orchitis and serum antibody to testicular antigens within 20 days after immunization. The lesions were located in testis (100%), rete testis (37%), cauda epididymis (21%), and vas deferens (37%). Ductus efferentes and caput epididymis were only rarely affected. Early lesions in the seminiferous tubules were characterized by peritubular and/or intratubular accumulation of eosinophils, neutrophils, lymphocytes, and macrophages. This was followed by aspermatogenesis. Late lesions included massive necrosis and extensive fibrosis of the seminiferous tubules. Disruption of blood-testis barrier on day 20 was evidenced by the detection of 1) perfused lanthanum deposits between Sertoli cells and surrounding inflammatory cells inside the seminiferous tubules, 2) deposits of endogenous mouse IgG in germinal epithelium, and 3) probable immune complexes (granular C3) surrounding seminiferous tubules. Murine EAO differed from that of the guinea pig in the lack of involvement of the ductus efferentes, the extensive necrosis, the abundant polymorphonuclear eosinophils in the lesion, and the exquisite requirement of concomitant injection of B. pertussis extract.     

Surfactant alterations in acute inflammatory lung injury from aspiration of acid and gastric particulates

This study examines surfactant dysfunction in rats with inflammatory lung injury from intratracheal instillation of hydrochloric acid (ACID, pH 1.25), small nonacidified gastric particles (SNAP), or combined acid and small gastric particles (CASP). Rats given CASP had the most severe lung injury at 6, 24, and 48 h based on decreases in arterial oxygenation and increases in erythrocytes, total leukocytes, neutrophils, total protein, and albumin in bronchoalveolar lavage (BAL). The content of large surfactant aggregates in BAL was reduced in all forms of aspiration injury, but decreases were greatest in rats given CASP. Large aggregates from aspiration-injured rats also had decreased levels of phosphatidylcholine (PC) and increased levels of lyso-PC and total protein compared with saline controls (abnormalities for CASP were greater than for SNAP or ACID alone). The surface tension-lowering ability of large surfactant aggregates on a bubble surfactometer was impaired in rats with aspiration injury at 6, 24, and 48 h, with the largest activity reductions found in animals given CASP. There were strong statistical correlations between surfactant dysfunction (increased minimum surface tension and reduced large aggregate content) and the severity of lung injury based on arterial oxygenation and levels of albumin, protein, and erythrocytes in BAL (P < 0.0001). Surfactant dysfunction also correlated strongly with reduced lung volumes during inflation and deflation (P = 0.0004-0.005). These results indicate that surfactant abnormalities are functionally important in gastric aspiration lung injury and contribute significantly to the increased severity of injury found in CASP compared with ACID or SNAP alone.     

A new experimental murine model for lipopolysaccharide-mediated lethal shock with lung injury

We have recently established a new experimental murine model for lipopolysaccharide (LPS)-mediated lethal shock with lung-specific injury. Severe lung injury is induced by administration of LPS into α-galactosylceramide (α-GalCer)-sensitized mice; the mice died with acute lung injury and respiratory distress within 24 h. α-GalCer activates natural killer T (NKT) cells in the lungs and liver, and induces the production of interferon (IFN)-γ. However, IFN-γ signaling is only triggered in the lungs and makes them susceptible to LPS. On the other hand, IFN-γ signaling is inhibited in liver and results in few hepatic lesions. Unlike liver NKT cells, lung NKT cells fail to produce interleukin (IL)-4, which down-regulates the IFN-γ signaling, in response to α-GalCer. The differential cytokine profile between lung and liver NKT cells may lead to organ-specific lung lesions. The experimental system using α-GalCer sensitization could be a useful experimental model for clinical endotoxic or septic shock as it presents respiratory failure, a typical manifestation in severe septic patients. In this review, key evidence and the introducuction of the detailed mechanism of LPS-mediated lung-specific injury in α-GalCer-sensitized mice is provided. In particular, the molecular background of organ-specific development of lung injury in the model is focused on.     

Role of different nitric oxide synthase isoforms in a murine model of acute lung injury and sepsis

Excessive production of nitric oxide (NO) by NO synthase (NOS) with subsequent formation of peroxynitrite and poly(adenosine diphosphate ribose) is critically implemented in the pathophysiology of acute lung injury and sepsis. To elucidate the roles of different isoforms of NOS, we tested the effects of non-selective NOS inhibition and neuronal NOS (nNOS)- and inducible NOS (iNOS)-gene deficiency on the pulmonary oxidative and nitrosative stress reaction in a murine sepsis model. The injury was induced by four sets of cotton smoke using an inhalation chamber and subsequent intranasal administration of live Pseudomonas aeruginosa (3.2 × 10⁷ colony-forming units). In wild type mice, the injury was associated with excessive releases of pro-inflammatory cytokines in the plasma, enhanced neutrophil accumulation, increased lipid peroxidation, and excessive formation of reactive nitrogen species and vascular endothelial growth factor in the lung. Both nNOS- and iNOS-gene deficiency led to significantly reduced oxidative and nitrosative stress markers in the lung, but failed to significantly improve survival. Treatment with a non-selective NOS inhibitor failed to reduce the oxidative and nitrosative stress reaction to the same extent and even tended to increase mortality. In conclusion, the current study demonstrates that both nNOS and iNOS are partially responsible for the pulmonary oxidative and nitrosative stress reaction in this model. Future studies should investigate the effects of specific pharmacological inhibition of nNOS and iNOS at different time points during the disease process.     

Dopamine inhibits pulmonary edema through the VEGF-VEGFR2 axis in a murine model of acute lung injury

The neurotransmitter dopamine and its dopamine receptor D2 (D2DR) agonists are known to inhibit vascular permeability factor/vascular endothelial growth factor (VEGF)-mediated angiogenesis and vascular permeability. Lung injury is a clinical syndrome associated with increased microvascular permeability. However, the effects of dopamine on pulmonary edema, a phenomenon critical to the pathophysiology of both acute and chronic lung injuries, have yet to be established. Therefore, we sought to determine the potential therapeutic effects of dopamine in a murine model of lipopolysaccharide (LPS)-induced acute lung injury (ALI). Compared with sham-treated controls, pretreatment with dopamine (50 mg/kg body wt) ameliorated LPS-mediated edema formation and lowered myeloperoxidase activity, a measure of neutrophil infiltration. Moreover, dopamine significantly increased survival rates of LPS-treated mice, from 0-75%. Mechanistically, we found that dopamine acts through the VEGF-VEGFR2 axis to reduce pulmonary edema, as dopamine pretreatment in LPS-treated mice resulted in decreased serum VEGF, VEGFR2 phosphorylation, and endothelial nitric oxide synthase phosphorylation. We used D2DR knockout mice to confirm that dopamine acts through D2DR to block vascular permeability in our lung injury model. As expected, a D2DR agonist failed to reduce pulmonary edema in D2DR(-/-) mice. Taken together, our results suggest that dopamine acts through D2DR to inhibit pulmonary edema-associated vascular permeability, which is mediated through VEGF-VEGFR2 signaling and conveys protective effects in an ALI model.     

Meconium aspiration produces airway hyperresponsiveness and eosinophilic inflammation in a murine model

Meconium aspiration syndrome is a cause of significant morbidity and mortality in the perinatal period and has been implicated in the pathogenesis of airway dysfunction. In this study, we developed a murine model to evaluate the effects of meconium aspiration on airway physiology and lung cellular responses. Under light anesthesia, BALB/c mice received a single intratracheal instillation of meconium or physiological saline. Respiratory mechanics were measured in unrestrained animals and expressed as percent increase in enhanced pause to increasing concentrations of methacholine (MCh). Furthermore, we assessed the changes in cells and cytokines into the bronchoalveolar lavage fluid (BALF). We found meconium aspiration produced increased airway responsiveness to MCh at 7 days. These functional changes were associated with lymphocytic/eosinophilic inflammation, goblet cell metaplasia, and increased concentrations of IL-5 and IL-13 in the BALF. Our findings suggest meconium aspiration leads to alterations of airway function, lung eosinophilia, goblet cell metaplasia, and cytokine imbalance, thus providing the first evidence of meconium-induced airway dysfunction in a mouse model.     

Genetic basis of murine responses to hyperoxia-induced lung injury

To evaluate the effect of genetic background on oxygen (O₂) toxicity, nine genetically diverse mouse strains (129/SvIm, A/J, BALB/cJ, BTBR+(T)/tf/tf, CAST/Ei, C3H/HeJ, C57BL/6J, DBA/2J, and FVB/NJ) were exposed to more than 99% O₂ for 72 h. Immediately following the hyperoxic challenge, the mouse strains demonstrated distinct pathophysiologic responses. The BALB/cJ and CAST/Ei strains, which were the only strains to demonstrate mortality from the hyperoxic challenges, were also the only strains to display significant neutrophil infiltration into their lower respiratory tract. In addition, the O₂-challenged BALB/cJ and CAST/Ei mice were among six strains (A/J, BALB/cJ, CAST/Ei, BTBR+(T)/tf/tf, DBA/2J, and C3H/HeJ) that had significantly increased interleukin 6 concentrations in the whole lung lavage fluid and were among all but one strain that had large increases in lung permeability compared with air-exposed controls. In contrast, the DBA/2J strain was the only strain not to have any significant alterations in lung permeability following hyperoxic challenge. The expression of the extracellular matrix proteins, including collagens I, III, and IV, fibronectin I, and tenascin C, also varied markedly among the mouse strains, as did the activities of total superoxide dismutase (SOD) and manganese-SOD (Mn-SOD or SOD2). These data suggest that the response to O₂ depends, in part, on the genetic background and that some of the strains analyzed can be used to identify specific loci and genes underlying the response to O₂.     

A micro-CT analysis of murine lung recruitment in bleomycin-induced lung injury.

The effects of lung injury on pulmonary recruitment are incompletely understood. X-ray computed tomography (CT) has been a valuable tool in assessing changes in recruitment during lung injury. With the development of preclinical CT scanners designed for thoracic imaging in rodents, it is possible to acquire high-resolution images during the evolution of a pulmonary injury in living mice. We quantitatively assessed changes in recruitment caused by intratracheal bleomycin at 1 and 3 wk after administration using micro-CT in 129S6/SvEvTac mice. Twenty female mice were administered 2.5 U of bleomycin or saline and imaged with micro-CT at end inspiration and end expiration. Mice were extubated and allowed to recover from anesthesia and then reevaluated in vivo for quasi-static compliance measurements, followed by harvesting of the lungs for collagen analysis and histology. CT images were converted to histograms and analyzed for mean lung attenuation (MLA). MLA was significantly greater for bleomycin-exposed mice at week 1 for both inspiration (P<0.0047) and exhalation (P<0.0377) but was not significantly different for week 3 bleomycin-exposed mice. However, week 3 bleomycin-exposed mice did display significant increases in MLA shift from expiration to inspiration compared with either group of control mice (P<0.005), suggesting increased lung recruitment at this time point. Week 1 bleomycin-exposed mice displayed normal shifts in MLA with inspiration, suggesting normal lung recruitment despite significant radiographic and histological changes. Lung alveolar recruitment is preserved in a mouse model of bleomycin-induced parenchymal injury despite significant changes in radiographic and physiological parameters.     

Superoxide production by rat neutrophils in the oleic acid model of lung injury

The purpose of this study was to investigate the superoxide anion (O2-)-generating capacity of neutrophils isolated from rats at various stages of oleic acid(OA)-induced lung injury. Neutrophils were collected from blood, bronchoalveolar lavage (BAL), and peritoneal cavity (glycogen induced) after OA administration. Control neutrophils were collected from the blood of normal animals as a representative of nonprimed cells that produce low levels of O2-. A second control was the glycogen-elicited peritoneal neutrophil of normal animals which represented primed cells that produce enhanced levels of O2-. The ability of the neutrophils to produce O2- was evaluated by using both myristate acetate and opsonized zymosan as stimulants. Neutrophils isolated from blood and BAL from OA-injured lungs produced low levels of O2- and resembled closely the circulating, nonprimed neutrophil. Myeloperoxidase levels were measured in plasma and BAL and were found to be elevated in BAL of OA-injured animals. The inability of neutrophils to produce high levels of O2- and the elevation of myeloperoxidase suggest that neutrophils present in the lung may have degranulated in response to prior activation and are therefore incapable of further superoxide production.     

TLR4 signaling-induced heme oxygenase upregulation in the acute lung injury: role in hemorrhagic shock and two-hit induced lung inflammation

Resuscitated hemorrhagic shock is believed to promote the development of acute lung injury (ALI) by priming the immune system for an exaggerated inflammatory response to a second trivial stimulus. This work explored effects of TLR4 on hemorrhage-induced ALI and “second-hit” responses, and further explore the mechanisms involved in “second-hit” responses. Expression of HO-1, IL-10, lung W/D and MPO markedly increased at nearly all time-points examined in HSR/LPS group as compared with sham/LPS group in WT mice. In HSR/LPS mice, the induced amount of IL-10 and the expressions of HO-1 of WT mice were significantly higher compared with TLR-4d/d. This study provides in vivo evidence that pulmonary infections after LPS instillation contribute to local tissue release of pro-inflammatory mediators after HSR systemic. Activation of TLR4 might induce HO-1 expression and HO-1 modulates proinflammatory responses that are triggered via TLR4 signaling.     

Inhibition of Pyk2 blocks lung inflammation and injury in a mouse model of acute lung injury

Background

Proline-rich tyrosine kinase 2 (Pyk2) is essential in neutrophil degranulation and chemotaxis in vitro. However, its effect on the process of lung inflammation and edema formation during LPS induced acute lung injury (ALI) remains unknown. The goal of the present study was to determine the effect of inhibiting Pyk2 on LPS-induced acute lung inflammation and injury in vivo.

Methods

C57BL6 mice were given either 10 mg/kg LPS or saline intratracheally. Inhibition of Pyk2 was effected by intraperitoneal administration TAT-Pyk2-CT 1 h before challenge. Bronchoalveolar lavage analysis of cell counts, lung histology and protein concentration in BAL were analyzed at 18 h after LPS treatment. KC and MIP-2 concentrations in BAL were measured by a mouse cytokine multiplex kit. The static lung compliance was determined by pressure-volume curve using a computer-controlled small animal ventilator. The extravasated Evans blue concentration in lung homogenate was determined spectrophotometrically.

Results

Intratracheal instillation of LPS induced significant neutrophil infiltration into the lung interstitium and alveolar space, which was attenuated by pre-treatment with TAT-Pyk2-CT. TAT-Pyk2-CT pretreatment also attenuated 1) myeloperoxidase content in lung tissues, 2) vascular leakage as measured by Evans blue dye extravasation in the lungs and the increase in protein concentration in bronchoalveolar lavage, and 3) the decrease in lung compliance. In each paradigm, treatment with control protein TAT-GFP had no blocking effect. By contrast, production of neutrophil chemokines MIP-2 and keratinocyte-derived chemokine in the bronchoalveolar lavage was not reduced by TAT-Pyk2-CT. Western blot analysis confirmed that tyrosine phosphorylation of Pyk2 in LPS-challenged lungs was reduced to control levels by TAT-Pyk2-CT pretreatment.

Conclusions

These results suggest that Pyk2 plays an important role in the development of acute lung injury in mice and that pharmacological inhibition of Pyk2 might provide a potential therapeutic strategy in the pretreatment for patients at imminent risk of developing acute lung injury.     

Oleic acid lung injury in sheep

Intravenous infusion of oleic acid into experimental animals causes acute lung injury resulting in pulmonary edema. We investigated the mechanism of oleic acid lung injury in sheep. In experiments with anesthetized and unanesthetized sheep with lung lymph fistulas, we measured pulmonary arterial and left atrial pressures, cardiac output, lung lymph flow, and lymph and plasma protein concentrations. We injured the lungs with intravenous infusions of oleic acid at doses ranging from 0.015 to 0.120 ml/kg. We found that oleic acid caused reproducible dose-related increases in pulmonary arterial pressure and pulmonary vascular resistance, arterial hypoxemia, and increased protein-rich lung lymph flow and extravascular lung water. The lung fluid balance changes were characteristic of increased permeability pulmonary edema. Infusion of the esterified fat triolein had no hemodynamic or lung fluid balance effects. Depletion of leukocytes with a nitrogen mustard or platelets with an antiplatelet serum had no effect on oleic acid lung injury. Treatment of sheep before injury with methylprednisolone 30 mg/kg or ibuprofen 12.5-15.0 mg/kg also had no effects. Unlike other well-characterized sheep lung injuries, injury caused by oleic acid does not require participation of leukocytes.     

Characterisation and validation of a new murine model of global ischaemia-reperfusion injury

A specially designed Langendorff apparatus was constructed to allow perfusion of the isolated mouse heart. Hearts were randomised into groups to receive differing periods of global (zero flow) ischaemia or continuous perfusion (controls). During reperfusion, recovery of baseline force was recorded and perfusate collected for LDH assay (U/L/g wet weight). After 30 min reperfusion, hearts were stained with tetrazolium and planimetry performed to measure infarct size. Dose-response relationships were demonstrated for all 3 end-points against duration of ischaemic insult. Functional recovery and enzyme leakage correlated well with infarct size (r = 0.77, p < 0.001 and r = 0.73, p < 0.001 respectively). Transgenic mice may now be used to study the effect of specific phenotypic changes on the pathogenesis of ischaemia-reperfusion injury using a reliable and reproducible technique.     

Mast cells in a murine lung ischemia-reperfusion model of primary graft dysfunction

Primary graft dysfunction (PGD), as characterized by pulmonary infiltrates and high oxygen requirements shortly after reperfusion, is the major cause of early morbidity and mortality after lung transplantation. Donor, recipient and allograft-handling factors are thought to contribute, although new insights regarding pathogenesis are needed to guide approaches to prevention and therapy. Mast cells have been implicated in ischemic tissue injury in other model systems and in allograft rejection, leading to the hypothesis that mast cell degranulation contributes to lung injury following reperfusion injury.We tested this hypothesis in a mouse model of PGD involving reversible disruption of blood flow to one lung. Metrics of injury included albumin permeability, plasma extravasation, lung histopathology, and mast cell degranulation. Responses were assessed in wild-type (Kit^+/+) and mast cell-deficient (Kit^W-sh/W-sh) mice. Because mouse lungs have few mast cells compared with human lungs, we also tested responses in mice with lung mastocytosis generated by injecting bone marrow-derived cultured mast cells (BMCMC).We found that ischemic lung responses of mast cell-deficient Kit^W-sh/W-sh mice did not differ from those of Kit^+/+ mice, even after priming for injury using LPS. Degranulated mast cells were more abundant in ischemic than in non-ischemic BMCMC-injected Kit^W-sh/W-sh lungs. However, lung injury in BMCMC-injected Kit^W-sh/W-sh and Kit^+/+ mice did not differ in globally mast cell-deficient, uninjected Kit^W-sh/W-sh mice or in wild-type Kit^+/+ mice relatively deficient in lung mast cells.These findings predict that mast cells, although activated in lungs injured by ischemia and reperfusion, are not necessary for the development of PGD.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-014-0095-0) contains supplementary material, which is available to authorized users.