Trauma is the leading cause of death and disability in patients aged 1-46 y. Severely injured patients experience considerable blood loss and hemorrhagic shock requiring treatment with massive ...transfusion of red blood cells (RBCs). Preclinical and retrospective human studies in trauma patients have suggested that poorer therapeutic efficacy, increased severity of organ injury, and increased bacterial infection are associated with transfusion of large volumes of stored RBCs, although the mechanisms are not fully understood.
We developed a murine model of trauma hemorrhage (TH) followed by resuscitation with plasma and leukoreduced RBCs (in a 1:1 ratio) that were banked for 0 (fresh) or 14 (stored) days. Two days later, lungs were infected with Pseudomonas aeruginosa K-strain (PAK). Resuscitation with stored RBCs significantly increased the severity of lung injury caused by P. aeruginosa, as demonstrated by higher mortality (median survival 35 h for fresh RBC group and 8 h for stored RBC group; p < 0.001), increased pulmonary edema (mean 95% CI 106.4 μl 88.5-124.3 for fresh RBCs and 192.5 μl 140.9-244.0 for stored RBCs; p = 0.003), and higher bacterial numbers in the lung (mean 95% CI 1.2 × 10(7) -1.0 × 10(7) to 2.5 × 10(7) for fresh RBCs and 3.6 × 10(7) 2.5 × 10(7) to 4.7 × 10(7) for stored RBCs; p = 0.014). The mechanism underlying this increased infection susceptibility and severity was free-heme-dependent, as recombinant hemopexin or pharmacological inhibition or genetic deletion of toll-like receptor 4 (TLR4) during TH and resuscitation completely prevented P. aeruginosa-induced mortality after stored RBC transfusion (p < 0.001 for all groups relative to stored RBC group). Evidence from studies transfusing fresh and stored RBCs mixed with stored and fresh RBC supernatants, respectively, indicated that heme arising both during storage and from RBC hemolysis post-resuscitation plays a role in increased mortality after PAK (p < 0.001). Heme also increased endothelial permeability and inhibited macrophage-dependent phagocytosis in cultured cells. Stored RBCs also increased circulating high mobility group box 1 (HMGB1; mean 95% CI 15.4 ng/ml 6.7-24.0 for fresh RBCs and 50.3 ng/ml 12.3-88.2 for stored RBCs), and anti-HMGB1 blocking antibody protected against PAK-induced mortality in vivo (p = 0.001) and restored macrophage-dependent phagocytosis of P. aeruginosa in vitro. Finally, we showed that TH patients, admitted to the University of Alabama at Birmingham ER between 1 January 2015 and 30 April 2016 (n = 50), received high micromolar-millimolar levels of heme proportional to the number of units transfused, sufficient to overwhelm endogenous hemopexin levels early after TH and resuscitation. Limitations of the study include lack of assessment of temporal changes in different products of hemolysis after resuscitation and the small sample size precluding testing of associations between heme levels and adverse outcomes in resuscitated TH patients.
We provide evidence that large volume resuscitation with stored blood, compared to fresh blood, in mice increases mortality from subsequent pneumonia, which occurs via mechanisms sensitive to hemopexin and TLR4 and HMGB1 inhibition.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Traumatic brain injury (TBI) is the leading cause of injury-related death and disability in patients under the age of 46 years. Survivors of the initial injury often endure systemic complications ...such as pulmonary infection, and
is one of the most common causes of nosocomial pneumonia in intensive care units. Female patients are less likely to develop secondary pneumonia after TBI, and pre-clinical studies have revealed a salutary role for estrogen after trauma. Therefore, we hypothesized that female mice would experience less mortality after post-TBI pneumonia with
. We employed a mouse model of TBI followed by
pneumonia. Male mice had greater mortality and impaired lung bacterial clearance after post-TBI pneumonia compared with female mice. This was confirmed as a difference in sex hormones, as oophorectomized wild-type mice had mortality and lung bacterial clearance similar to male mice. There were differences in tumor necrosis factor-α secretion in male and female alveolar macrophages after
infection. Finally, injection of male or oophorectomized wild-type female mice with estrogen restored lung bacterial clearance and prevented mortality. Our model of TBI followed by
pneumonia is among the first to reveal sex dimorphism in secondary, long-term TBI complications.
Acute respiratory distress syndrome (ARDS) is a life‐threatening illness characterized by decreased alveolar‐capillary barrier function, pulmonary edema consisting of proteinaceous fluid, and ...inhibition of net alveolar fluid transport responsible for resolution of pulmonary edema. There is currently no pharmacotherapy that has proven useful to prevent or treat ARDS, and two trials using beta‐agonist therapy to treat ARDS demonstrated no effect. Prior studies indicated that IL‐8‐induced heterologous desensitization of the beta2‐adrenergic receptor (β2‐AR) led to decreased beta‐agonist‐induced mobilization of cyclic adenosine monophosphate (cAMP). Interestingly, phosphodiesterase (PDE) 4 inhibitors have been used in human airway diseases characterized by low intracellular cAMP levels and increases in specific cAMP hydrolyzing activity. Therefore, we hypothesized that PDE4 would mediate IL‐8‐induced heterologous internalization of the β2‐AR and that PDE4 inhibition would restore beta‐agonist‐induced functions. We determined that CINC‐1 (a functional IL‐8 analog in rats) induces internalization of β2‐AR from the cell surface, and arrestin‐2, PDE4, and β2‐AR form a complex during this process. Furthermore, we determined that cAMP associated with the plasma membrane was adversely affected by β2‐AR heterologous desensitization. Additionally, we determined that rolipram, a PDE4 inhibitor, reversed CINC‐1‐induced derangements of cAMP and also caused β2‐AR to successfully recycle back to the cell surface. Finally, we demonstrated that rolipram could reverse CINC‐1‐mediated inhibition of beta‐agonist‐induced alveolar fluid clearance in a murine model of trauma‐shock. These results indicate that PDE4 plays a role in CINC‐1‐induced heterologous internalization of the β2‐AR; PDE4 inhibition reverses these effects and may be a useful adjunct in particular ARDS patients.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Slope was significantly non-zero for number of units (r2 = 0.91, p<0.001). https://doi.org/10.1371/journal.pmed.1002991.g001 In the Results, in the subsection “Heme levels in patients after TH and ...resuscitation”, there is an error in the fifth sentence of the first paragraph. While the absolute concentration of these mediators is important, the relative concentrations of hemoglobin and free heme, compared to Hp and Hpx respectively is likely of greater clinical significance; Hp and Hpx are the endogenous primary defense mechanisms protecting against hemolysis-dependent injury. (2018) Role of heme in lung bacterial infection after trauma hemorrhage and stored red blood cell transfusion: A preclinical experimental study.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Pulmonary edema associated with increased vascular permeability is a severe complication of Pseudomonas (P.) aeruginosa‐induced acute lung injury. The mechanisms underlying P aeruginosa‐induced ...vascular permeability are not well understood. In the present study, we investigated the role of neuronal Wiskott Aldrich syndrome protein (N‐WASP) in modulating P aeruginosa‐induced vascular permeability. Using lung microvascular endothelial and alveolar epithelial cells, we demonstrated that N‐WASP downregulation attenuated P aeruginosa‐induced actin stress fiber formation and prevented paracellular permeability. P aeruginosa‐induced dissociation between VE‐cadherin and β‐catenin, but increased association between N‐WASP and VE‐cadherin, suggesting a role for N‐WASP in promoting P aeruginosa‐induced adherens junction rupture. P aeruginosa increased N‐WASP‐Y256 phosphorylation, which required the activation of Rho GTPase and focal adhesion kinase. Increased N‐WASP‐Y256 phosphorylation promotes N‐WASP and integrin αVβ6 association as well as TGF‐β‐mediated permeability across alveolar epithelial cells. Inhibition of N‐WASP‐Y256 phosphorylation by N‐WASP‐Y256F overexpression blocked N‐WASP effects in P aeruginosa‐induced actin stress fiber formation and increased paracellular permeability. In vivo, N‐WASP knockdown attenuated the development of pulmonary edema and improved survival in a mouse model of P aeruginosa pneumonia. Together, our data demonstrate that N‐WASP plays an essential role in P aeruginosa‐induced vascular permeability and pulmonary edema through the modulation of actin cytoskeleton dynamics.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
is a lethal pathogen that causes high mortality and morbidity in immunocompromised and critically ill patients. The type III secretion system (T3SS) of
mediates many of the adverse effects of ...infection with this pathogen, including increased lung permeability in a Toll-like receptor 4/RhoA/PAI-1 (plasminogen activator inhibitor-1)-dependent manner. α-Tocopherol has antiinflammatory properties that may make it a useful adjunct in treatment of this moribund infection. We measured transendothelial and transepithelial resistance, RhoA and PAI-1 activation, stress fiber formation,
T3SS exoenzyme (ExoY) intoxication into host cells, and survival in a murine model of pneumonia in the presence of
and pretreatment with α-tocopherol. We found that α-tocopherol alleviated
-mediated alveolar endothelial and epithelial paracellular permeability by inhibiting RhoA, in part, via PAI-1 activation, and increased survival in a mouse model of
pneumonia. Furthermore, we found that α-tocopherol decreased the activation of RhoA and PAI-1 by blocking the injection of T3SS exoenzymes into alveolar epithelial cells.
is becoming increasingly antibiotic resistant. We provide evidence that α-tocopherol could be a useful therapeutic agent for individuals who are susceptible to infection with
, such as those who are immunocompromised or critically ill.
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