Role of alveolar macrophages in the inflammatory response after trauma

Micromorphological features and interleukin 6, 8, and 18 expressions in post-mortem lung tissue in cases with acute respiratory distress syndrome

The purpose of this study was to analyze the presence of interleukins 6, 8, and 18 in post-mortem lung tissue of subjects deceased due to polytrauma. In addition to this, we have described different micromorphological features of lung tissue in ARDS cases associated with fatal traffic trauma. A total of 18 autopsy cases with ARDS after polytrauma and 15 control autopsy cases were analyzed in this study. From every subject, we collected one sample for each lung lobe. All of the histological sections were analyzed by using light microscopy, and for the purpose of ultrastructural analysis, we used transmission electron microscopy. Representative sections were further processed by way of immunohistochemistry analysis. Quantification of IL-6, IL-8, and IL-18-positive cells was conducted by applying the IHC score. We noticed that all samples of ARDS cases exhibited elements of the proliferative phase. Immunohistochemical analysis of lung tissue in patients with ARDS showed strong positive staining for IL-6 (2.8 ± 0.7), IL-8 (2.2 ± 1.3), and IL-18 (2.7 ± 1.2), while staining of the control samples resulted in no positivity to low/moderate positivity (for IL-6 1.4 ± 0.5; for IL-8 0.1 ± 0.4; for IL-18 0.6 ± 0.9). Only IL-6 correlated negatively with the patients' age (r =  -0.6805, p < 0.01). In this study, we described microstructural changes in lung sections of ARDS cases and control cases, as well as interleukins' expression, demonstrating that autopsy material is as informing as tissue samples collected by performing open lung biopsy.

Lung Protection After Severe Thermal Burns With Adenosine, Lidocaine, and Magnesium (ALM) Resuscitation and Importance of Shams in a Rat Model

The management of severe burns remains a complex challenge. Adenosine, lidocaine, and magnesium (ALM) resuscitation therapy has been shown to protect against hemorrhagic shock and traumatic injury. The aim of the present study was to investigate the early protective effects of small-volume ALM fluid resuscitation in a rat model of 30% total body surface area (TBSA) thermal injury. Male Sprague-Dawley rats (320-340 g; n = 25) were randomly assigned to: 1) Sham (surgical instrumentation and saline infusion, without burn, n = 5), 2) Saline resuscitation group (n = 10), or 3) ALM resuscitation group (n = 10). Treatments were initiated 15-min after burn trauma, including 0.7 mL/kg 3% NaCl ± ALM bolus and 0.25-0.5 mL/kg/h 0.9% NaCl ± ALM drip, with animals monitored to 8.25-hr post-burn. Hemodynamics, cardiac function, blood chemistry, hematology, endothelial injury markers and histopathology were assessed. Survival was 100% for Shams and 90% for both ALM and Saline groups. Shams underwent significant physiological, immune and hematological changes over time as a result of surgical traums. ALM significantly reduced malondialdehyde levels in the lungs compared to Saline (P = .023), and showed minimal alveolar destruction and inflammatory cell infiltration (P < .001). ALM also improved cardiac function and oxygen delivery (21%, P = .418 vs Saline), reduced gut injury (P < .001 vs Saline), and increased plasma adiponectin (P < .001 vs baseline). Circulating levels of the acute phase protein alpha 1-acid glycoprotein (AGP) increased 1.6-times (P < .001), which may have impacted ALM's therapeutic efficacy. We conclude that small-volume ALM therapy significantly reduced lung oxidative stress and preserved alveolar integrity following severe burn trauma. Further studies are required to assess higher ALM doses with longer monitoring periods.

ESTROGEN ALLEVIATES POSTHEMORRHAGIC SHOCK MESENTERIC LYMPH-MEDIATED LUNG INJURY THROUGH AUTOPHAGY INHIBITION

ABSTRACT

Background: Hemorrhagic shock-induced acute lung injury (ALI) is commonly associated with the posthemorrhagic shock mesenteric lymph (PHSML) return. Whether excessive autophagy is involved in PHSML-mediated ALI remains unclear. The relationship between estrogen treatment and PHSML or autophagy needs to verify. The current study will clarify the role of estrogen in reducing PHSML-mediated ALI through inhibition of autophagy. Methods: First, a hemorrhagic shock model in conscious rats was used to observe the effects of 17β-estradiol (E2) on intestinal blood flow, pulmonary function, intestinal and pulmonary morphology, and expression of autophagy marker proteins. Meanwhile, the effect of PHSML and autophagy agonist during E2 treatment was also investigated. Secondly, rat primary pulmonary microvascular endothelial cells were used to observe the effect of PHSML, PHSML plus E2, and E2-PHSML (PHSML obtained from rats treated by E2) on the cell viability. Results: Hemorrhagic shock induced intestinal and pulmonary tissue damage and increased wet/dry ratio, reduced intestinal blood flow, along with pulmonary dysfunction characterized by increased functional residual capacity and lung resistance and decreased inspiratory capacity and peak expiratory flow. Hemorrhagic shock also enhanced the autophagy levels in intestinal and pulmonary tissue, which was characterized by increased expressions of LC3 II/I and Beclin-1 and decreased expression of p62. E2 treatment significantly attenuated these adverse changes after hemorrhagic shock, which was reversed by PHSML or rapamycin administration. Importantly, PHSML incubation decreased the viability of pulmonary microvascular endothelial cells, while E2 coincubation or E2-treated lymph counteracted the adverse roles of PHSML. Conclusions: The role of estrogen reducing PHSML-mediated ALI is associated with the inhibition of autophagy.

Effect of Hydrogen on AM Pyroptosis Induced by Severe Burns in Rats

Background: Hydrogen has anti-inflammatory and antioxidant effects and is beneficial to multiple organs. However, its effect on alveolar macrophage (AM) pyroptosis induced by burns is still unclear. The purpose of this research was to study the possible positive effects of hydrogen on burn-induced lung injury and the effects of hydrogen on AM pyroptosis during acute lung injury (ALI) induced by burns. Methods: In this study, histological changes in rat lungs in vivo were evaluated by micro-CT, and histological changes in isolated lungs were evaluated by hematoxylin and eosin (HE) staining. The expressions of leucine rich repeat (LRR) and pyrin domain (PYD) containing protein 3 (NLRP3), caspase-1 and Gasdermin-D (GSDMD) were analyzed by Western blotting. The expression of GSDMD was measured by immunofluorescence to evaluate the levels of lung inflammation and pyroptosis. The level of inflammation was assessed by enzyme-linked immunosorbent assay (ELISA). Pyroptosis was observed by transmission electron microscopy. Results: We observed that severe burn resulted in increased IL-1β and IL-18, overexpression of NLRP3 and caspase-1 proteins, and pyroptosis in rat lung tissues, as demonstrated by GSDMD overexpression and electron microscopy of AMs. We also observed that hydrogen treatment partially reversed the increase in lung tissue density and reduced pulmonary inflammation. Moreover, hydrogen reduced the HE pathological injury score in the lung tissues of severely burned rats. Hydrogen treatment significantly reduced the contents of IL-1β and IL-18 in the lung tissues and decreased the expression of NLRP3, caspase-1 and GSDMD proteins compared with the burn group. Transmission electron microscopy results also showed that the number of AM membrane pores was significantly reduced in the hydrogen treatment group. Conclusions: The results of this study suggest that hydrogen may protect against ALI induced by burn injury by inhibiting pyroptosis of macrophages via NLRP3.

Shock lung is not "wet" but characterized as necroptotic inflammation in a mouse model of hypotension

OBJECTIVES

Hypotension episodes before or after donor brain death are assumed to trigger hypoxia-reoxygenation, causing diffuse alveolar-capillary damage via necrosis. However, alveolar-capillary membranes have direct access to oxygen in alveoli. We hypothesized hypotension-induced lung injury is not diffuse alveolar-capillary damage but interstitial inflammation resulting from nonhypoxic lung ischemia and systemic responses to hypoxic extrapulmonary ischemia.

METHODS

The 4-hour hypotension model was established by subjecting C57BL/6J mice to 4-hour hypotension at 15 ± 5 mm Hg of mean artery pressure and resuscitated with whole shed blood and norepinephrine. Nonhypoxic lung ischemia model was established by 4-hour left pulmonary artery ligation. At 24 hours postprocedure, an arterial blood gas analysis and a gastroduodenal occult blood test were conducted. Lung samples were assessed for histology, cytokine transcripts, regulated cell death, and alveolar-capillary permeability.

RESULTS

The 4-hour hypotension model had an intraoperative mortality rate of 17.7% (41/231) and a stress-ulcer bleeding rate of 15.3% (29/190). No signs of alveolar flooding were observed in both models. Four-hour hypotension without stress ulcer showed normal oxygenation and permeability but increased interstitial infiltration, transcription of Tnf and Il1b, phosphorylation of MLKL and RIPK3, and cleaved caspase 3 compared with 4-hour pulmonary artery ligation and naïve control. Animals that developed stress ulcer presented with worse pulmonary infiltration, intracellular edema, and oxygenation but just slightly increased permeability. Immunoblotting showed significant upregulations of protein expression and phosphorylation of MLKL and RIPK3, cleaved Caspase-3, but not its prototype in 4-hour hypotension with stress ulcer.

CONCLUSIONS

Hypotensive lung injury is essentially a nonhypoxic ischemia-reperfusion injury enhanced by systemic responses. It is predominated by necroptosis-induced inflammation rather than necrosis-induced diffuse alveolar-capillary damage.

A 2A ADENOSINE RECEPTORS REGULATE MULTIPLE ORGAN FAILURE AFTER HEMORRHAGIC SHOCK IN MICE

ABSTRACT

Trauma hemorrhagic shock (T/HS) is a clinical condition that causes multiple organ failure that needs rapid intervention. Restricted oxygen at the cellular level causes inflammation and subsequent cell death. Adenosine triphosphate is the universal intracellular energy currency and an important extracellular inflammatory signaling molecule. Adenosine, an endogenous nucleotide formed as a result of the breakdown of adenosine triphosphate, is also released during T/HS. Adenosine binds to four G protein-coupled receptors (A 1R , A 2a , A 2b , A 3R ) called adenosine receptors or P1 receptors. In the present study, we evaluated the effect of activation, inactivation, and genetic absence of A2aR (A2aR -/- mice) on T/HS-induced multiple organ failure. Wild-type mice were pretreated (30 min before shock induction) with an agonist or antagonist and then subjected to T/HS by withdrawing arterial blood and maintaining the blood pressure between 28 and 32 mm Hg. A2aR -/- mice were subjected to T/HS in the absence of pharmacologic treatment. Neutrophil sequestration was assessed by detecting myeloperoxidase, and Evans blue dye (EBD) method was used to analyze lung permeability. Blood and lung inflammatory cytokine levels were determined by sandwich enzyme-linked immunosorbent assay. The liver enzymes aspartate aminotransferase and alanine aminotransferase were determined spectrophotometrically from plasma. Activation of the apoptotic cascade was evaluated using a mouse apoptosis array. Our results demonstrate that the selective A2aR agonist CGS21680 decreases lung neutrophil sequestration, lung proinflammatory cytokines IL-6 and TNF-α, and bronchoalveolar lavage EBD. Pretreatment with the selective antagonist ZM241385 and genetic blockade in A2aR -/- mice increased neutrophil sequestration, proinflammatory cytokine levels, and bronchoalveolar lavage fluid EBD. The myeloperoxidase level in the lung was also increased in A2aR -/- mice. We observed that antiapoptotic markers decreased significantly with the absence of A2aR in the lung and spleen after T/HS. In conclusion, our data demonstrate that activation of A2aR regulates organ injury and apoptosis in the setting of T/HS.

Evaluating immunohaematological profile among COVID-19 active infection and recovered patients in Ghana

Introduction

The rapid spread of COVID-19 has been a global public health problem and it is yet to be put under control. Active COVID-19 is associated with unrestrained secretion of pro-inflammatory cytokines and imbalances in haematological profile including anaemia, leukocytosis and thrombocytopaenia. However, the haematological profile and immune status following recovery from COVID-19 has not been recognized. We evaluated the immunohaematological profile among COVID-19 patients with active infection, recovered cases and unexposed healthy individuals in the Ashanti region of Ghana.

Methodology

A total of 95 adult participants, consisting of 35 positive, 30 recovered and 30 unexposed COVID-19 negative individuals confirmed by RT-PCR were recruited for the study. All the patients had the complete blood count performed using the haematological analyzer Sysmex XN-1500. Their plasma cytokine levels of interleukin (IL)-1β, IL-6, IL-10, IL-17, tumour necrosis factor-alpha (TNF-α) and interferon gamma (IFN-γ) were analysed using ELISA. Statistical analyses were performed on R statistical software.

Result

The Patients with COVID-19 active infection had significantly higher levels of IL10 (181±6.14 pg/mL vs 155.00±14.32 pg/mL vs 158.80±11.70 pg/mL, p = 0.038), WBC count (5.5±0.4 x10⁹ /L vs 4.5±0.6 x10⁹ /L vs 3.8±0.5, p < 0.0001) and percentage basophil (1.8±0.1% vs 0.8±0.3% vs 0.7±0.2%, p = 0.0040) but significantly lower levels of IFN-γ (110.10±9.52 pg/mL vs 142.80±5.46 pg/mL vs 140.80±6.39 pg/mL, p = 0.021), haematocrit (24.1±3.7% vs 38.3± 3.0% vs 38.5±2.2%, p < 0.0001), haemoglobin concentration (9.4±0.1g/dl vs 12.5± 5.0g/dl vs 12.7±0.8, p < 0.0001) and MPV (9.8±0.2fL vs 11.1±0.5fL vs 11.6±0.3fL, p < 0.0001) compared to recovered and unexposed controls respectively. There were significant association between IL-1β & neutrophils (r = 0.42, p<0.05), IL-10 & WBC (r = 0.39, p<0.05), IL-10 & Basophils (r = -0.51, p<0.01), IL-17 & Neutrophil (r = 0.39, p<0.05) in the active COVID-19 cases.

Conclusion

COVID-19 active infection is associated with increased IL-10 and WBC with a concomitant decrease in IFN-γ and haemoglobin concentration. However, recovery from the disease is associated with immune recovery with appareantly normal haematological profile.

Pathophysiology in patients with polytrauma

The pathophysiology after polytrauma represents a complex network of interactions. While it was thought for a long time that the direct and indirect effects of hypoperfusion are most relevant due to the endothelial permeability changes, it was discovered that the innate immune response to trauma is equally important in modifying the organ response. Recent multi center studies provided a "genetic storm" theory, according to which certain neutrophil changes are activated at the time of injury. However, a second hit phenomenon can be induced by activation of certain molecules by direct organ injury, or pathogens (damage associated molecular patterns, DAMPS - pathogen associated molecular patterns, PAMPS). The interactions between the four pathogenetic cycles (of shock, coagulopathy, temperature loss and soft tissue injuries) and cross-talk between coagulation and inflammation have also been identified as important modifiers of the clinical status. In a similar fashion, overzealous surgeries and their associated soft tissue injury and blood loss can induce secondary worsening of the patient condition. Therefore, staged surgeries in certain indications represent an important alternative, to allow for performing a "safe definitive surgery" strategy for major fractures. The current review summarizes all these situations in a detailed fashion.

The journey of SARS-CoV-2 in human hosts: a review of immune responses, immunosuppression, and their consequences

Coronavirus disease 2019 (COVID-19) is a highly infectious viral disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Laboratory findings from a significant number of patients with COVID-19 indicate the occurrence of leukocytopenia, specifically lymphocytopenia. Moreover, infected patients can experience contrasting outcomes depending on lymphocytopenia status. Patients with resolved lymphocytopenia are more likely to recover, whereas critically ill patients with signs of unresolved lymphocytopenia develop severe complications, sometimes culminating in death. Why immunodepression manifests in patients with COVID-19 remains unclear. Therefore, the evaluation of clinical symptoms and laboratory findings from infected patients is critical for understanding the disease course and its consequences. In this review, we take a logical approach to unravel the reasons for immunodepression in patients with COVID-19. Following the footprints of the virus within host tissues, from entry to exit, we extrapolate the mechanisms underlying the phenomenon of immunodepression.

The Protective Activity of Penehyclidine Hydrochloride against Renal Ischemia/Reperfusion-Mediated NLRP3 Inflammasome Activation is Induced by SIRT1

Background: The activation of alveolar macrophages (AMs) modulated via leucine-rich repeat (NLR) pyrin domain containing 3 (NLRP3) inflammasome activation is key to the progression of renal ischemia/reperfusion (rI/R)-mediated acute lung injury (ALI). Sirtuin-1 (SIRT1) can attenuate NLRP3 inflammasome activation during I/R stress and may be an important mechanism underlying ALI pathogenesis. Penehyclidine hydrochloride (PHC), an anticholinergic drug, exerts protective effects against rI/R-mediated ALI. This study aimed to decipher the effects of PHC on SIRT1 activation and the underlying mechanism of the protective activity of PHC against rI/R-mediated ALI.Materials and methods: We used an ALI rat model and the rat AMs cell line NR8383 to assess the degree of lung injury in vivo and in vitro.Results: The results show that PHC attenuates rI/R-mediated lung injury indices, myeloperoxidase, and apoptosis in vivo. It decreases the rI/R-mediated release of prostaglandin E2 and nitric oxide, mitochondrial reactive oxygen species production, and the activity of NADPH oxidase-4 in vitro. PHC ameliorates the rI/R-induced activation of the thioredoxin-interacting protein, caspase 1 (P10 unit), and NLRP3 inflammasome, along with reduced activation of interleukin-1β and interleukin-18 in vitro. We show that PHC alleviates the rI/R-induced reduction of SIRT1 and the depletion of SIRT1 eliminates the ameliorating activity of PHC on the NLRP3 inflammasome activation in vitro. Conclusions: In summary, the findings suggest that PHC ameliorates the rI/R-mediated ALI through the SIRT1-mediated NLRP3 inflammasome activation.

Peptidylarginine Deiminase 2 Knockout Improves Survival in hemorrhagic shock

BACKGROUND

The peptidylarginine deiminase (PAD) family converts arginine into citrulline through protein citrullination. PAD2 and PAD4 inhibitors can improve survival in hemorrhagic shock (HS). However, the impact of isoform-specific PAD inhibition in improving survival has not been studied. In this study, we utilize selective Pad2 knockout mice to elucidate loss of function of PAD2 leads to pro-survival effect in HS.

METHODS

HS: Pad2 and wild-type (WT) mice (n = 5/group) were subjected to lethal HS (55% volume hemorrhage). Survival was monitored over 7 days. Myocardial infarction (MI): Pad2 and WT mice (n = 9/group) were subjected to MI by permanent LAD ligation to examine the effect of ischemia on the heart. After 24 h cardiac function and infarct size were measured.

RESULTS

HS: Pad2 mice demonstrated 100% survival compared with 0% for WT mice (P = 0.002). In a sub-lethal HS model, cardiac β-catenin levels were higher in Pad2 compared with WT after 24 h. MI: WT mice demonstrated larger MI (75%) compared with Pad2 (60%) (P < 0.05). Pad2 had significantly higher ejection fraction and fractional shortening compared with WT (P < 0.05).

CONCLUSIONS

Pad2 improves survival in lethal HS. Possible mechanisms by which loss of PAD2 function improves survival include the activation of cell survival pathways, improved tolerance of cardiac ischemia, and improved cardiac function during ischemia. PAD2 is promising as a future therapeutic target for the treatment of HS and cardiac ischemia.

Preclinical models for studying immune responses to traumatic injury

Traumatic injury initiates a large and complex immune response in the minutes after the initial insult, comprising of simultaneous pro- and anti-inflammatory responses. In patients that survive the initial injury, these immune responses are believed to contribute towards complications such as the development of sepsis and multiple organ dysfunction syndrome. These post-traumatic complications affect a significant proportion of patients and are a major contributing factor for poor outcomes and an increased burden on healthcare systems. Therefore, understanding the immune responses to trauma is crucial for improving patient outcomes through the development of novel therapeutics and refining resuscitation strategies. In order to do this, preclinical animal models must mimic human immune responses as much as possible, and as such, we need to understand the constraints of each species in the context of trauma. A number of species have been used in this field; however, these models are limited by their genetic background and their capacity for recapitulating human immune function. This review provides a brief overview of the immune response in critically injured human patients and discusses the most commonly used species for modelling trauma, focusing on how their immune response to serious injury and haemorrhage compares to that of humans.

Programmed cell death-1/programmed cell death-ligand 1 inhibitors exert antiapoptosis and antiinflammatory activity in lipopolysaccharide stimulated murine alveolar macrophages

Acute lung injury caused by sepsis remains one of the most difficult challenges faced by patients in intensive care units and is associated with a high mortality rate. The aim of the present study was to investigate whether programmed cell death (PD)-1/programmed cell death-ligand 1 (PD-L1) inhibitors reduce alveolar macrophage apoptosis, reduce inflammatory factor release and relieve inflammation. For this purpose, murine alveolar macrophages, MH-S, were cultured and divided into control, lipopolysaccharide (LPS) and LPS+BMS-1 (PD-1/PD-L1 inhibitors) groups. LPS (10 ng/ml) was added to the LPS and LPS+BMS-1 groups for 24 h and PD-1/PD-L1 inhibitor BMS-1 (1 µmol/l) was added to the LPS+BMS-1 group for 72 h. PD-1 mRNA expression was detected using reverse transcription-quantitative PCR and PD-1 protein expression was detected using western blotting in the control, LPS and LPS+BMS-1 groups of macrophages. MH-S apoptosis was detected using flow cytometry with Annexin V/PI staining. The levels of the inflammatory factors interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α and IL-10 were detected by ELISA. Murine alveolar macrophages expressed PD-1 at both the molecular and protein levels and PD-1 expression was increased in MH-S cells stimulated with LPS. Compared with the LPS group, the expression of PD-1 in the LPS+BMS-1 group was significantly decreased. Flow cytometry demonstrated that there was increased apoptosis of alveolar macrophages in the LPS group compared with the control group, whereas, alveolar macrophages notably decreased apoptosis in the LPS+BMS-1 group compared with the LPS group. There was no statistical difference between the control group and the LPS+BMS-1 group. IL-1β, IL-6, TNF-α and IL-10 were increased in the LPS group compared with the control group. The levels of IL-1β, IL-6 and TNF-α in the LPS+BMS-1 group were lower compared with those in the LPS group whereas IL-10 was further increased. In vitro, the PD-1/PD-L1 inhibitor, BMS-1, decreases alveolar macrophage apoptosis compared with the LPS group to maintain effective immune clearance and reduce inflammatory factor release. This decreased the inflammatory response and reduced acute lung injury caused by sepsis. Therefore, PD-1/PD-L1 inhibitors may be a potential therapeutic target for acute lung injury in patients with sepsis.

Bone marrow-derived mesenchymal stem cells modulate autophagy in RAW264.7 macrophages via the phosphoinositide 3-kinase/protein kinase B/heme oxygenase-1 signaling pathway under oxygen-glucose deprivation/restoration conditions

Background

Autophagy of alveolar macrophages is a crucial process in ischemia/reperfusion injury-induced acute lung injury (ALI). Bone marrow-derived mesenchymal stem cells (BM-MSCs) are multipotent cells with the potential for repairing injured sites and regulating autophagy. This study was to investigate the influence of BM-MSCs on autophagy of macrophages in the oxygen-glucose deprivation/restoration (OGD/R) microenvironment and to explore the potential mechanism.

Methods

We established a co-culture system of macrophages (RAW264.7) with BM-MSCs under OGD/R conditions in vitro. RAW264.7 cells were transfected with recombinant adenovirus (Ad-mCherry-GFP-LC3B) and autophagic status of RAW264.7 cells was observed under a fluorescence microscope. Autophagy-related proteins light chain 3 (LC3)-I, LC3-II, and p62 in RAW264.7 cells were detected by Western blotting. We used microarray expression analysis to identify the differently expressed genes between OGD/R treated macrophages and macrophages co-culture with BM-MSCs. We investigated the gene heme oxygenase-1 (HO-1), which is downstream of the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) signaling pathway.

Results

The ratio of LC3-II/LC3-I of OGD/R treated RAW264.7 cells was increased (1.27 ± 0.20 vs. 0.44 ± 0.08, t = 6.67, P < 0.05), while the expression of p62 was decreased (0.77 ± 0.04 vs. 0.95 ± 0.10, t = 2.90, P < 0.05), and PI3K (0.40 ± 0.06 vs. 0.63 ± 0.10, t = 3.42, P < 0.05) and p-Akt/Akt ratio was also decreased (0.39 ± 0.02 vs. 0.58 ± 0.03, t = 9.13, P < 0.05). BM-MSCs reduced the LC3-II/LC3-I ratio of OGD/R treated RAW264.7 cells (0.68 ± 0.14 vs. 1.27 ± 0.20, t = 4.12, P < 0.05), up-regulated p62 expression (1.10 ± 0.20 vs. 0.77 ± 0.04, t = 2.80, P < 0.05), and up-regulated PI3K (0.54 ± 0.05 vs. 0.40 ± 0.06, t = 3.11, P < 0.05) and p-Akt/Akt ratios (0.52 ± 0.05 vs. 0.39 ± 0.02, t = 9.13, P < 0.05). A whole-genome microarray assay screened the differentially expressed gene HO-1, which is downstream of the PI3K/Akt signaling pathway, and the alteration of HO-1 mRNA and protein expression was consistent with the data on PI3K/Akt pathway.

Conclusions

Our results suggest the existence of the PI3K/Akt/HO-1 signaling pathway in RAW264.7 cells under OGD/R circumstances in vitro, revealing the mechanism underlying BM-MSC-mediated regulation of autophagy and enriching the understanding of potential therapeutic targets for the treatment of ALI.

Tissue-Resident Macrophages in the Control of Infection and Resolution of Inflammation

ABSTRACT

Macrophage, as an integral component of the immune system and the first responder to local damage, is on the front line of defense against infection. Over the past century, the prevailing view of macrophage origin states that all macrophage populations resided in tissues are terminally differentiated and replenished by monocytes from bone-marrow progenitors. Nonetheless, this theory has been reformed by ground-breaking discoveries from the past decades. It is now believed that tissue-resident macrophages (TRMs) are originated from the embryonic precursors and seeded in tissue prenatally. They can replenish via self-renewal throughout the lifespan. Indeed, recent studies have demonstrated that tissue-resident macrophages should not be classified by the over-simplified macrophage polarization (M1/M2) dogma during inflammation. Moreover, multiple lines of evidence have indicated that tissue-resident macrophages play critical roles in maintaining tissue homeostasis and facilitating tissue repair through controlling infection and resolving inflammation. In this review, we summarize the properties of resident macrophages in the lung, spleen, and heart, and further highlight the impact of TRM populations on inflammation control and tissue repair. We also discuss the potential role of local proliferation in maintaining a physiologically stable TRM pool in response to acute inflammation.

Early local neutralization of CC16 in sepsis‑induced ALI following blunt chest trauma leads to delayed mortality without benefitting overall survival

Blunt thoracic trauma (TxT) is a common injury pattern in polytraumatized patients. When combined with a secondary trigger, TxT often results in acute lung injury (ALI), which negatively affects outcomes. Recent findings suggest that ALI is caused by both local and systemic inflammatory reactions. Club cell protein (CC)16 is an anti‑inflammatory peptide associated with lung injury following TxT. Recently, the anti‑inflammatory properties of endogenous CC16 in a murine model of TxT with subsequent cecal‑ligation and puncture (CLP) as the secondary hit were demonstrated by our group. The present study aimed to determine whether CC16 neutralization improves survival following 'double‑hit'‑induced ALI. For this purpose, a total of 120 C57BL/6N mice were subjected to TxT, followed by CLP after 24 h. Sham‑operated animals underwent anesthesia without the induction of TxT + CLP. CC16 neutralization was performed by providing a CC16 antibody intratracheally following TxT (early) or following CLP (late). Survival was assessed in 48 animals for 6 days after CLP. Sacrifice was performed 6 or 24 h post‑CLP to evaluate the anti‑inflammatory effect of CC16. The results revealed that CC16 neutralization enhanced pro‑inflammatory CXCL1 levels, thereby confirming the anti‑inflammatory characteristics of CC16 in this model. Early CC16 neutralization immediately following TxT significantly prolonged survival within 60 h; however, the survival rate did not change until 6 days post‑trauma. Late CC16 neutralization did not provide any survival benefits. On the whole, the present study demonstrated that neutralizing CC16 confirmed its anti‑inflammatory potential in this double‑hit ALI model. Early CC16 neutralization prolonged survival within 60 h; however, no survival benefits were observed after 6 days post‑CLP in any group.

Inflammation, Thrombosis, and Destruction: The Three-Headed Cerberus of Trauma- and SARS-CoV-2-Induced ARDS

Physical trauma can be considered an unrecognized "pandemic" because it can occur anywhere and affect anyone and represents a global burden. Following severe tissue trauma, patients frequently develop acute lung injury (ALI) and/or acute respiratory distress syndrome (ARDS) despite modern surgical and intensive care concepts. The underlying complex pathophysiology of life-threatening ALI/ARDS has been intensively studied in experimental and clinical settings. However, currently, the coronavirus family has become the focus of ALI/ARDS research because it represents an emerging global public health threat. The clinical presentation of the infection is highly heterogeneous, varying from a lack of symptoms to multiple organ dysfunction and mortality. In a particular subset of patients, the primary infection progresses rapidly to ALI and ARDS. The pathophysiological mechanisms triggering and driving severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced ALI/ARDS are still poorly understood. Although it is also generally unknown whether insights from trauma-induced ARDS may be readily translated to SARS-CoV-2-associated ARDS, it was still recommended to treat coronavirus-positive patients with ALI/ARDS with standard protocols for ALI/ARDS. However, this strategy was questioned by clinical scientists, because it was documented that some severely hypoxic SARS-CoV-2-infected patients exhibited a normal respiratory system compliance, a phenomenon rarely observed in ARDS patients with another underlying etiology. Therefore, coronavirus-induced ARDS was defined as a specific ARDS phenotype, which accordingly requires an adjusted therapeutic approach. These suggestions reflect previous attempts of classifying ARDS into different phenotypes that might overall facilitate ARDS diagnosis and treatment. Based on the clinical data from ARDS patients, two major phenotypes have been proposed: hyper- and hypo-inflammatory. Here, we provide a comparative review of the pathophysiological pathway of trauma-/hemorrhagic shock-induced ARDS and coronavirus-induced ARDS, with an emphasis on the crucial key points in the pathogenesis of both these ARDS forms. Therefore, the manifold available data on trauma-/hemorrhagic shock-induced ARDS may help to better understand coronavirus-induced ARDS.

GTS-21 Reduces Inflammation in Acute Lung Injury by Regulating M1 Polarization and Function of Alveolar Macrophages

BACKGROUND

Acute lung injury (ALI) is a severe outcome of sepsis. Alveolar macrophages (AMs) play key roles in defense, resolution in ALI. The polarization of AMs is dependent on micro environmental stimuli and might influence the progression of ALI. Gainesville Tokushima scientists (GTS)-21, a selective α7 nicotinic acetylcholine receptor agonist of the cholinergic anti-inflammatory pathway (CAP), has recently been established to be promising in the treatment of ALI. However, the molecular mechanism underlying the GTS-21-mediated suppression of inflammatory responses has been explored only partially. In this study, we examined the relation between GTS-21 and AM polarization in ALI.

METHODS

The adoptive transfer of M1 (classically activated) and M2 (alternatively activated)-polarized AMs was performed to AM-depleted ALI mice, along with the administration of GTS-21 in a murine model of lipopolysaccharide (LPS)-induced ALI and in isolated AMs that had been stimulated by LPS in vitro.

RESULTS

The adoptive transfer of M1-polarized AMs aggravated the inflammatory response in the lung in contrast to the adoptive transfer of M2-polarized AMs. GTS-21 protected the lung from the effect of LPS, preventing injury and decreasing the number of AMs, AM-related pro-inflammatory cytokine levels, high mobility group box 1 expression levels in AMs. In addition, GTS-21 significantly diminished the number of M1-polarized AM and increased the number of M2-polarized AM, by flow cytometry, RT-PCR, enzyme-linked immunosorbent assay, and the Arg1 and iNOS activity assays.

CONCLUSION

The GTS-21 substantially ameliorates LPS-induced ALI. This protection is predominantly associated with the inhibition of pulmonary AM M1 polarization and alteration in AM function.

Mdivi-1 attenuates lipopolysaccharide-induced acute lung injury by inhibiting MAPKs, oxidative stress and apoptosis

Sepsis is among the most devastating events in intensive care units. As a complication of sepsis, acute lung injury (ALI) is common and highly associated with poor outcome. The present study demonstrated that abnormal mitochondrial dynamics play a pivotal role in lipopolysaccharide (LPS)-induced ALI. Inhibiting the mitochondrial fission with the specific inhibitor-1 (Mdivi-1) ameliorated ALI as assessed by hematoxylin and eosin (H&E) staining and wet/dry ratio. Furthermore, Mdivi-1 reduced mitogen-activated protein kinases (MAPKs) activation, oxidative stress and apoptosis in the lungs. Plasma pro-inflammation cytokines were also reduced significantly in Mdivi-1-treated mice. In vitro study revealed that Mdivi-1 protected the macrophages from LPS-induced MAPKs activation, oxidative stress and cell apoptosis. Mdivi-1 also inhibited the release of pro-inflammatory cytokines. Morphological analysis showed that Mdivi-1 rescued the macrophages from LPS-induced mitochondrial fragmentation. Moreover, LPS treatment induced significant phosphorylation of Drp1 at Ser616, dephosphorylation at Ser637 and translocation of Drp1 from the cytoplasm to mitochondria, while Mdivi-1 inhibited those effects. Thus, modification of fission to rebuild mitochondrial homeostasis may offer an innovative opportunity for developing therapeutic strategies against ALI.

Therapeutic effect and mechanism study of L-cysteine derivative 5P39 on LPS-induced acute lung injury in mice

Organosulfur compounds, such as L-cysteine, allicin and other sulfur-containing organic compounds in Allium species, have been proposed to possess many important physiological and pharmacological functions. A novel L-cysteine derivative, t-Butyl S-allylthio-L-cysteinate (5P39), was designed and synthesized by combining L-cysteine derivative and allicin pharmacophore through a disulfide bond. This study aimed to explore the effects and mechanisms of 5P39 on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice. At the experimental concentration (5, 10 and 20 μM), 5P39 suppressed the excessive secretion of nitric oxide (NO) and interleukin-6 (IL-6) in mice peritoneal macrophages stimulated by LPS. A mouse model of ALI was established by tracheal instillation of LPS for 2 h before 5P39 (30 and 60 mg/kg) administration. The results showed that 5P39 treatment down-regulated the wet/dry weight ratio (W/D ratio) of lungs and reduced the protein concentration, the number of total cells as well as the myeloperoxidase (MPO) activity in bronchoalveolar lavage fluid (BALF). 5P39 administration improved the histopathological changes of lungs in ALI mice with the decreased levels of pro-inflammatory cytokines in BALF. The inhibitory effects of 5P39 on the toll-like receptor 4 (TLR4) expression and macrophages accumulation in lung tissues were observed by immunohistochemistry. Additionally, 5P39 significantly attenuated the LPS-activated high expression of key proteins in TLR4/MyD88 signaling pathway. Taken together, the present study showed that 5P39 effectively alleviate the severity of ALI, and its mechanism might relate to the inhibition of LPS-activated TLR4/MyD88 signaling pathway, demonstrating a promising potential for further development into an anti-inflammatory drug candidate.

PolyI:C Upregulated CCR5 and Promoted THP-1-Derived Macrophage Chemotaxis via TLR3/JMJD1A Signalling

Objective

This study aimed to evaluate the specific roles of polyinosinic:polycytidylic acid (polyI:C) in macrophage chemotaxis and reveal the potential regulatory mechanisms related to chemokine receptor 5 (CCR5).

Materials and Methods

In this experimental study, THP-1-derived macrophages (THP1-Mφs) induced from THP- 1 monocytes were treated with 25 μg/mL polyI:C. Toll-like receptor 3 (TLR3), Jumonji domain-containing protein (JMJD)1A, and JMJD1C small interfering RNA (siRNAs) were transfected into THP1-Mφs. Quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR) was used to detect the expression levels of TLR3, CCR5, 23 Jumonji C domain-containing histone demethylase family members, JMJD1A, and JMJD1C in THP1-Mφs with different siRNAs transfections. Western blot was performed to detect JMJD1A, JMJD1C, H3K9me2, and H3K9me3 expressions. A transwell migration assay was conducted to detect THP1-Mφ chemotaxis toward chemokine ligand 3 (CCL3). A chromatin immunoprecipitation (ChIP) assay was performed to detect H3K9me2-CCR5 complexes in THP1- Mφs.

Results

PolyI:C significantly upregulated CCR5 in THP1-Mφs and promoted chemotaxis toward CCL3 (P<0.05); these effects were significantly inhibited by TLR3 siRNA (P<0.01). JMJD1A and JMJD1C expression was significantly upregulated in polyI:C-stimulated THP1-Mφs, while only JMJD1A siRNA decreased CCR5 expression (P<0.05). JMJD1A siRNA significantly increased H3K9me2 expression in THP1-Mφs but not in polyI:C-stimulated THP1-Mφs. The ChIP result revealed that polyI:C significantly downregulated H3K9me2 in the promoter region of CCR5 in THP1- Mφs.

Conclusion

PolyI:C can enhance THP1-Mφ chemotaxis toward CCL3 regulated by TLR3/JMJD1A signalling and activate CCR5 expression by reducing H3K9me2 in the promoter region of CCR5.

Cynanchum atratum Ameliorates Airway Inflammation via Maintaining Alveolar Barrier and Regulating Mast Cell-Mediated Inflammatory Responses

Asthma is a common allergic airway inflammatory disease, characterized by abnormal breathing due to bronchial inflammation. Asthma aggravates the patient's quality of life and needs continuous pharmacological treatment. Therefore, discovery of drugs for the treatment of asthma is an important area of human health. The aim of the present study was to evaluate whether Cynanchum atratum extract (CAE) modulates the asthma-like allergic airway inflammation and to study its possible mechanism of action using ovalbumin (OVA)-induced airway inflammation and lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice, as well as a mast cell-based in vitro model. The histological analysis showed that CAE reduced the airway constriction and immune cell infiltration. CAE also inhibited release of β-hexosaminidase and expression of inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-4, and IL-5 in bronchoalveolar lavage fluid and lung tissues. In addition, CAE reduced the OVA-specific immunoglobulin (Ig) E, total IgE, IgG1, and IgG2a levels in the serum. In the LPS-induced ALI model, CAE suppressed the LPS-induced lung barrier dysfunction and the release of proinflammatory cytokines. Because allergic airway inflammatory responses are associated with the activation of mast cells, RBL-2H3 cells were used to evaluate the underlying mechanism of CAE effects. In RBL-2H3 cells, CAE down-regulated release of β-hexosaminidase and histamine by reducing the intracellular calcium influx. In addition, CAE suppressed the expression of proinflammatory cytokines by inhibiting nuclear translocation of nuclear factor-κB. Taken together, our findings suggest that CAE may help in the prevention or treatment of airway inflammatory diseases.

Protostemonine alleviates heat-killed methicillin-resistant Staphylococcus aureus-induced acute lung injury through MAPK and NF-κB signaling pathways

Acute lung injury (ALI) and its most severe form acute respiratory distress syndrome (ARDS) caused by gram-positive bacteria threatens human life because effective treatments and medicines is unavailable. Protostemonine (PSN), an active alkaloid mainly isolated from the roots of Stemona sesslifolia, has anti-inflammatory effects on asthma and gram-negative bacteria-induced ALI. Here, we found that PSN exhibits anti-inflammatory effects and alleviates heat-killed methicillin-resistant Staphylococcus aureus (HKMRSA)-induced pneumonia. PSN treatment significantly attenuated HKMRSA-induced pathological injury, pulmonary neutrophil infiltration, tissue permeability and the production of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) in murine ALI model. In addition, PSN decreased the content of TNF-α, IL-1β, IL-6 and the expression of iNOS, as well as the production of NO in HKMRSA-induced bone marrow derived macrophages (BMDMs). Furthermore, treatment with PSN suppressed the activation of MAPKs (e.g. p38 MAPK, JNK and ERK) and NF-κB. Collectively, our results suggest that PSN ameliorates gram-positive bacteria-induced ALI in mice by inhibition of the MAPK and NF-κB signaling pathways, and our studies suggest that PSN might be a novel candidate for treating ALI/ARDS.

Modeling trauma in rats: similarities to humans and potential pitfalls to consider

Trauma is the leading cause of mortality in humans below the age of 40. Patients injured by accidents frequently suffer severe multiple trauma, which is life-threatening and leads to death in many cases. In multiply injured patients, thoracic trauma constitutes the third most common cause of mortality after abdominal injury and head trauma. Furthermore, 40-50% of all trauma-related deaths within the first 48 h after hospital admission result from uncontrolled hemorrhage. Physical trauma and hemorrhage are frequently associated with complex pathophysiological and immunological responses. To develop a greater understanding of the mechanisms of single and/or multiple trauma, reliable and reproducible animal models, fulfilling the ethical 3 R's criteria (Replacement, Reduction and Refinement), established by Russell and Burch in 'The Principles of Human Experimental Technique' (published 1959), are required. These should reflect both the complex pathophysiological and the immunological alterations induced by trauma, with the objective to translate the findings to the human situation, providing new clinical treatment approaches for patients affected by severe trauma. Small animal models are the most frequently used in trauma research. Rattus norvegicus was the first mammalian species domesticated for scientific research, dating back to 1830. To date, there exist numerous well-established procedures to mimic different forms of injury patterns in rats, animals that are uncomplicated in handling and housing. Nevertheless, there are some physiological and genetic differences between humans and rats, which should be carefully considered when rats are chosen as a model organism. The aim of this review is to illustrate the advantages as well as the disadvantages of rat models, which should be considered in trauma research when selecting an appropriate in vivo model. Being the most common and important models in trauma research, this review focuses on hemorrhagic shock, blunt chest trauma, bone fracture, skin and soft-tissue trauma, burns, traumatic brain injury and polytrauma.

Crosstalk signaling between alveoli and capillaries

Crosstalk signaling between the closely juxtaposed epithelial and endothelial membranes of pulmonary alveoli establishes the lung's immune defense against inhaled and blood-borne pathogens. The crosstalk can occur in a forward direction, as from alveolus to capillary, or in a reverse direction, as from capillary to alveolus. The crosstalk direction likely depends on the site at which pathogens first initiate signaling. Thus, forward crosstalk may occur when inhaled pathogens encounter the alveolar epithelium, while reverse crosstalk may result from interactions of blood-borne pathogens with the endothelium. Here, we review the factors that regulate these two directions of signaling.

BTP2, a Store-Operated Calcium Channel Inhibitor, Attenuates Lung Ischemia-Reperfusion Injury in Rats

Lung ischemia-reperfusion (I/R) injury is a critical complication following a lung transplant, cardiopulmonary bypass, pulmonary embolism, and trauma. Immune cells and their effector functions are involved in the lung I/R injury. Store-operated calcium channels (SOCC) are highly Ca²⁺-selective cation channels and have crucial effects on the immune system. It has been indicated that BTP2, a potent SOCC blocker, could inhibit pro-inflammatory cytokine production from immune cells both in vitro and in vivo. Therefore, this study was conducted to investigate the beneficial effects of BTP2 on lung I/R injury in Sprague-Dawley (SD) rats. The left lungs of male SD rats underwent ischemia for 60 min and reperfusion for 2 h. Treated animals received BTP2 4 mg/kg or 10 mg/kg intraperitoneally 30 min before the ischemia. The results revealed that pretreatment with BTP2 markedly attenuated I/R injury-induced pulmonary edema, microvascular protein leakage, neutrophil infiltration, adhesion molecules, cytokine production (e.g., ICAM-1, TNF-α, IL-1β, and IL-2), and the transcription factor nuclear factor of activated T cells c1 nuclear translocation in the lung tissue. These findings indicate that BTP2 can be a potential therapeutic drug for lung I/R injury and suggest that SOCC may play a critical role in lung I/R injury.

Innate immune responses to trauma

Trauma can affect any individual at any location and at any time over a lifespan. The disruption of macrobarriers and microbarriers induces instant activation of innate immunity. The subsequent complex response, designed to limit further damage and induce healing, also represents a major driver of complications and fatal outcome after injury. This Review aims to provide basic concepts about the posttraumatic response and is focused on the interactive events of innate immunity at frequent sites of injury: the endothelium at large, and sites within the lungs, inside and outside the brain and at the gut barrier.

Tranexamic Acid Attenuates The Loss of Lung Barrier Function in a Rat Model of Polytrauma And Hemorrhage With Resuscitation

INTRODUCTION

Severe trauma, hemorrhage, and resuscitation can lead to a trauma-related acute lung injury that involves rapid infiltration of immune cells and platelets. This infiltration involves exymatic degradation of matrix proteins, including plasmin, and causes loss of barrier function. Since tranexamic acid (TXA) inhibits plasminogen/ plasmin binding to target substrates, it may attenuate loss of barrier function after severe trauma, hemorrhage, and resuscitation.

METHODS

Sprague-Dawley rats were subjected to polytrauma (laparotomy, and trauma to intestines, liver, right leg skeletal muscle, and right femur fracture), then bled 40% of their blood volume. One hour after completion of polytrauma and hemorrhage, resuscitation was begun with fresh whole blood (FWB) or FWB with prior bolus administration of TXA (10 mg/kg in 0.2 mL).

RESULTS

Polytrauma, hemorrhage, and resuscitation with FWB led to an elevation in lung water content that was significantly reduced with TXA administration. Polytrauma and hemorrhage led to rise in the number of neutrophils/monocytes and platelets in the lungs, and a rise in myeloperoxidase (MPO), neutrophil elastase and complement C5a content. While resuscitation with FWB significantly reduced the cellular infiltrate and MPO, FWB/TXA further reduced the levels of neutrophil/monocytes, neutrophil elastase, and complement C5a. Polytrauma and hemorrhage led to rise in lung plasmin activity that was significantly reduced with either FWB or FWB/TXA resuscitation.

CONCLUSION

Severe trauma and hemorrhage leads to increases in lung water content, and immune cell, platelets, MPO, elastase, and C5a content in lung tissue, all markers of inflammation and acute lung injury. The addition of TXA to FWB resuscitation markedly attenuated the rise in these parameters suggesting its utility in treating acute lung injury.

Phorbol ester (PMA)-treated U937 cells cultured on type I collagen-coated dish express a lower production of pro-inflammatory cytokines through lowered ROS levels in parallel with cell aggregate formation

The present study is aimed to investigate the effect of collagen I on U937 cells, human monocyte-like histiocytic lymphoma cell line. Differentiation of U937 cells was induced by phorbol ester (PMA) treatment. The cells were cultured on the collagen I-coated plate. PMA-stimulated U937 cells formed multicellular aggregates on collagen I-coated surface, whereas PMA-unstimulated cells kept themselves away off each other. Moreover, the levels of reactive oxygen species (ROS) and productions of pro-inflammatory cytokines such as IL-1β, TNFα and PGE2, pro-inflammatory mediator, were down-regulated in differentiated U937 cells cultured on collagen I-coated dishes. However, collagen I did not influence the capacity of E. coli phagocytosis. Cell aggregation as well as the down-regulation of IL-1β, TNFα and PGE2 caused by the culture on collagen I-coated surface were suppressed by ROS donor, tert-butylhydroperoxide (tBHP). The sizes of cell aggregates became bigger in differentiated U937 cells by treatment with ROS scavengers such as N-acetylcysteine (NAC), superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH). In conclusion, collagen I-coated culture induces the differentiated U937 cells to form cell aggregates and decreases the production of pro-inflammatory cytokines through down-regulating ROS generation.

D-β-Hydroxybutyrate and melatonin for treatment of porcine hemorrhagic shock and injury: a melatonin dose-ranging study

OBJECTIVE

Treatment with a combination of D-β-hydroxybutyrate (BHB) and melatonin (M) improves survival in hemorrhagic shock models. Our objective was to find the most effective melatonin concentration in combination with 4 molar BHB (4 M BHB). Survival and markers of organ injury were analyzed in pigs exposed to pulmonary contusion, liver crush injury, and hemorrhagic shock and treated with lactated Ringer's solution; 4 M BHB/43 mM M; 4 M BHB/20 mM M; 4 M BHB/10 mM M; 4 M BHB/4.3 mM M; or 4 M BHB/0.43 mM M. This work is an extension of a previously published research study.

RESULTS

Survival was highest in pigs receiving 4 M BHB/43 mM M (13/14), followed by lactated Ringer's solution (11/16) and BHB/M with decreased melatonin concentrations (4 M BHB/20 mM M 3/6, 4 M BHB/10 mM M 2/6, 4 M BHB/4.3 mM M 3/6, 4 M BHB/0.43 mM M 1/6, p = 0.011). High mortality was associated with increases in serum lactate, higher liver and muscle injury markers and decreases in PaO2:FiO2 ratios. Our study indicates that treatment with 4 M BHB and melatonin concentrations below 43 mM lack the survival benefit observed from 4 M BHB/43 mM melatonin in pigs experiencing hemorrhagic shock and polytrauma.

Rho-inhibiting C2IN-C3 fusion toxin inhibits chemotactic recruitment of human monocytes ex vivo and in mice in vivo

Bacterial protein toxins became valuable molecular tools for the targeted modulation of cell functions in experimental pharmacology and attractive therapeutics because of their potent and specific mode of action in human cells. C2IN-C3lim, a recombinant fusion toxin (~50 kDa) of the Rho-inhibiting C3lim from Clostridium (C.) limosum and a non-toxic portion of the C. botulinum C2 toxin (C2IN), is selectively internalized into the cytosol of monocytic cells where C3lim specifically ADP-ribosylates Rho A and -B, thereby inhibiting Rho-mediated signaling. Thus, we hypothesized that these unique features make C2IN-C3lim an attractive molecule for the targeted pharmacological down-regulation of Rho-mediated functions in monocytes. The analysis of the actin structure and the Rho ADP-ribosylation status implied that C2IN-C3lim entered the cytosol of primary human monocytes from healthy donors ex vivo within 1 h. Moreover, it inhibited the fMLP-induced chemotaxis of human monocytes in a Boyden chamber model ex vivo. Similarly, in a 3-dimensional ex vivo model of extravasation, single cell analysis revealed that C2IN-C3lim-treated cells were not able to move. In a clinically relevant mouse model of blunt chest trauma, the local application of C2IN-C3lim into the lungs after thorax trauma prevented the trauma-induced recruitment of monocytes into the lungs in vivo. Thus, C2IN-C3lim might be an attractive lead compound for novel pharmacological strategies to avoid the cellular damage response caused by monocytes in damaged tissue after trauma and during systemic inflammation. The results suggest that the pathophysiological role of clostridial C3 toxins might be a down-modulation of the innate immune system.

Dimethyl Sulfoxide Attenuates Acute Lung Injury Induced by Hemorrhagic Shock/Resuscitation in Rats

Inflammation following hemorrhagic shock/resuscitation (HS/RES) induces acute lung injury (ALI). Dimethyl sulfoxide (DMSO) possesses anti-inflammatory and antioxidative capacities. We sought to clarify whether DMSO could attenuate ALI induced by HS/RES. Male Sprague-Dawley rats were allocated to receive either a sham operation, sham plus DMSO, HS/RES, or HS/RES plus DMSO, and these were denoted as the Sham, Sham + DMSO, HS/RES, or HS/RES + DMSO group, respectively (n = 12 in each group). HS/RES was achieved by drawing blood to lower mean arterial pressure (40-45 mmHg for 60 min) followed by reinfusion with shed blood/saline mixtures. All rats received an intravenous injection of normal saline or DMSO immediately before resuscitation or at matching points relative to the sham groups. Arterial blood gas and histological assays (including histopathology, neutrophil infiltration, and lung water content) confirmed that HS/RES induced ALI. Significant increases in pulmonary expression of tumor necrosis factor-α (TNF-α), malondialdehyde, nuclear factor-kappa B (NF-κB), inducible nitric oxide synthase (iNOS), and cyclooxygenase 2 (COX-2) confirmed that HS/RES induced pulmonary inflammation and oxidative stress. DMSO significantly attenuated the pulmonary inflammation and ALI induced by HS/RES. The mechanisms for this may involve reducing inflammation and oxidative stress through inhibition of pulmonary NF-κB, TNF-α, iNOS, and COX-2 expression.

TLR4 signaling induces TLR3 up-regulation in alveolar macrophages during acute lung injury

Acute lung injury is a life-threatening inflammatory response caused by severe infection. Toll-like receptors in alveolar macrophages (AMΦ) recognize the molecular constituents of pathogens and activate the host's innate immune responses. Numerous studies have documented the importance of TLR-TLR cross talk, but few studies have specifically addressed the relationship between TLR4 and TLR3. We explored a novel mechanism of TLR3 up-regulation that is induced by LPS-TLR4 signaling in a dose- and time-dependent manner in AMΦ from C57BL/6 mice, while the LPS-induced TLR3 expression was significantly reduced in TLR4^-/- and Myd88^-/- mice and following pretreatment with a NF-κB inhibitor. The enhanced TLR3 up-regulation in AMΦ augmented the expression of cytokines and chemokines in response to sequential challenges with LPS and Poly I:C, a TLR3 ligand, which was physiologically associated with amplified AMΦ-induced PMN migration into lung alveoli. Our study demonstrates that the synergistic effect between TLR4 and TLR3 in macrophages is an important determinant in acute lung injury and, more importantly, that TLR3 up-regulation is dependent on TLR4-MyD88-NF-κB signaling. These results raise the possibility that bacterial infections can induce sensitivity to viral infections, which may have important implications for the therapeutic manipulation of the innate immune system.

Lung Ischemia-Reperfusion is a Sterile Inflammatory Process Influenced by Commensal Microbiota in Mice

Lung ischemia-reperfusion (IR) complicates numerous clinical processes, such as cardiac arrest, transplantation, and major trauma. These conditions generate sterile inflammation, which can cause or worsen acute lung injury. We previously reported that lung and systemic inflammation in a mouse model of ventilated lung IR depends on Toll-like receptor 4 (TLR-4) signaling and the presence of alveolar macrophages. Here, we tested the hypothesis that the intestinal microbiome has a role in influencing the inflammatory response to lung IR. Lung IR was created in intubated mechanically ventilated mice via reversible left pulmonary artery occlusion followed by reperfusion. Inflammatory markers and histology were tracked during varying periods of reperfusion (from 1 to 24 h). Separate groups of mice were given intestinally localized antibiotics for 8 to 10 weeks and then were subjected to left lung IR and analysis of lungs and plasma for markers of inflammation. Alveolar macrophages from antibiotic-treated or control mice were tested ex vivo for inflammatory responses to bacterial TLR agonists, namely, lipopolysaccharide and Pam3Cys. We found that inflammation generated by left lung IR was rapid in onset and dissipated within 12 to 24 h. Treatment of mice with intestinally localized antibiotics was associated with a marked attenuation of circulating and lung inflammatory markers as well as reduced histologic evidence of infiltrating cells and edema in the lung after IR. Alveolar macrophages from antibiotic-treated mice produced less cytokines ex vivo when stimulated with TLR agonists as compared with those from control mice. Our data indicate that the inflammatory response induced by nonhypoxic lung IR is transient and is strongly influenced by intestinal microbiota. Furthermore, these data suggest that the intestinal microbiome could potentially be manipulated to attenuate the post-IR pulmonary inflammatory response.

Video-assisted thoracoscopic surgery for retained hemothorax in blunt chest trauma

Purpose of review

In the last decade, video-assisted thoracoscopic surgery (VATS) has become a popular method in diagnosis and treatment of acute chest injuries. Except for patients with unstable vital signs who require larger surgical incisions to check bleeding, this endoscopic surgery could be employed in the majority of thoracic injury patients with stable vital signs.

Recent findings

In the past, VATS was used to evacuate traumatic-retained hemothorax. Recent study has revealed further that lung repair during VATS could decrease complications after trauma. Management of fractured ribs could also be assisted by VATS. Early VATS intervention within 7 days after injury can decrease the rate of posttraumatic infection and length of hospital stay. In studies of the pathophysiology of animal models, N-acetylcysteine and methylene blue were used in animals with blunt chest trauma and found to improve clinical outcomes.

Summary

Retained hemothorax derived from blunt chest trauma should be managed carefully and rapidly. Early VATS intervention is a well tolerated and reliable procedure that can be applied to manage this complication cost effectively.

ROS-Mediated NLRP3 Inflammasome Activity Is Essential for Burn-Induced Acute Lung Injury

The NLRP3 inflammasome is necessary for initiating acute sterile inflammation. However, its role in the pathogenesis of burn-induced acute lung injury (ALI) is unknown. This study aimed to determine the role of the NLRP3 inflammasome and the signaling pathways involved in burn-induced ALI. We observed that the rat lungs exhibited enhanced inflammasome activity after burn, as evidenced by increased levels of NLRP3 expression and Caspase-1 activity and augmented inflammatory cytokines. Inhibition of NLRP3 inflammasome by BAY11-7082 attenuated burn-induced ALI, as demonstrated by the concomitant remission of histopathologic changes and the reduction of myeloperoxidase (MPO) activity, inflammatory cytokines in rat lung tissue, and protein concentrations in the bronchoalveolar lavage fluid (BALF). In the in vitro experiments, we used AMs (alveolar macrophages) challenged with burn serum to mimic the postburn microenvironment and noted that the serum significantly upregulated NLRP3 inflammasome signaling and reactive oxygen species (ROS) production. The use of ROS scavenger N-acetylcysteine (NAC) partially reversed NLRP3 inflammasome activity in cells exposed to burn serum. These results indicate that the NLRP3 inflammasome plays an essential role in burn-induced ALI and that burn-induced NLRP3 inflammasome activity is a partly ROS-dependent process. Targeting this axis may represent a promising therapeutic strategy for the treatment of burn-induced ALI.

ROS-Mediated NLRP3 Inflammasome Activity Is Essential for Burn-Induced Acute Lung Injury

The NLRP3 inflammasome is necessary for initiating acute sterile inflammation. However, its role in the pathogenesis of burn-induced acute lung injury (ALI) is unknown. This study aimed to determine the role of the NLRP3 inflammasome and the signaling pathways involved in burn-induced ALI. We observed that the rat lungs exhibited enhanced inflammasome activity after burn, as evidenced by increased levels of NLRP3 expression and Caspase-1 activity and augmented inflammatory cytokines. Inhibition of NLRP3 inflammasome by BAY11-7082 attenuated burn-induced ALI, as demonstrated by the concomitant remission of histopathologic changes and the reduction of myeloperoxidase (MPO) activity, inflammatory cytokines in rat lung tissue, and protein concentrations in the bronchoalveolar lavage fluid (BALF). In the in vitro experiments, we used AMs (alveolar macrophages) challenged with burn serum to mimic the postburn microenvironment and noted that the serum significantly upregulated NLRP3 inflammasome signaling and reactive oxygen species (ROS) production. The use of ROS scavenger N-acetylcysteine (NAC) partially reversed NLRP3 inflammasome activity in cells exposed to burn serum. These results indicate that the NLRP3 inflammasome plays an essential role in burn-induced ALI and that burn-induced NLRP3 inflammasome activity is a partly ROS-dependent process. Targeting this axis may represent a promising therapeutic strategy for the treatment of burn-induced ALI.

ROS-Mediated NLRP3 Inflammasome Activity Is Essential for Burn-Induced Acute Lung Injury

The NLRP3 inflammasome is necessary for initiating acute sterile inflammation. However, its role in the pathogenesis of burn-induced acute lung injury (ALI) is unknown. This study aimed to determine the role of the NLRP3 inflammasome and the signaling pathways involved in burn-induced ALI. We observed that the rat lungs exhibited enhanced inflammasome activity after burn, as evidenced by increased levels of NLRP3 expression and Caspase-1 activity and augmented inflammatory cytokines. Inhibition of NLRP3 inflammasome by BAY11-7082 attenuated burn-induced ALI, as demonstrated by the concomitant remission of histopathologic changes and the reduction of myeloperoxidase (MPO) activity, inflammatory cytokines in rat lung tissue, and protein concentrations in the bronchoalveolar lavage fluid (BALF). In the in vitro experiments, we used AMs (alveolar macrophages) challenged with burn serum to mimic the postburn microenvironment and noted that the serum significantly upregulated NLRP3 inflammasome signaling and reactive oxygen species (ROS) production. The use of ROS scavenger N-acetylcysteine (NAC) partially reversed NLRP3 inflammasome activity in cells exposed to burn serum. These results indicate that the NLRP3 inflammasome plays an essential role in burn-induced ALI and that burn-induced NLRP3 inflammasome activity is a partly ROS-dependent process. Targeting this axis may represent a promising therapeutic strategy for the treatment of burn-induced ALI.

Houttuyniacordata Thunb. polysaccharides ameliorates lipopolysaccharide-induced acute lung injury in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Houttuynia cordata (HC) has been used as a folk therapy to treat pulmonary infections. This study aimed to determine the role and mechanism of action of polysaccharides isolated from HC (HCP) in lipopolysaccharide (LPS)-induced ALI in the mice.

MATERIALS AND METHODS

LPS was delivered by the intratracheal route to Balb/c mice 2h before HCP (40, 80 and 160mg/kg) administration.

RESULTS

The number of total cells, protein and tumor necrosis factor-α (TNF-α) concentrations in bronchoalveolar lavage fluid, the wet/dry weight ratio (w/d) of lungs and pulmonary pathology of each mouse were analyzed, it was found that HCP significantly alleviated ALI induced by LPS. Moreover, in lungs of mice, it was found that the infiltration of inflammatory cells, the expression of Toll-like receptor 4 and complement deposition were significantly decreased by HCP treatment. In vitro assays showed that C5a, a complement activation product, induced significant macrophage migration and treatment with HCP prevented it. The in vitro results also proved that LPS increased nitric oxide and pro-inflammatory cytokines (TNF-α, interleukin-6, and interleukin-1β) production, and HCP antagonized these effects of LPS. It was also found that HCP alone augmented secretion of some pro-inflammatory cytokines.

CONCLUSION

These results indicate that HCP may alleviate LPS induced lung inflammatory injury, which may be associated with its inhibitory effect on the over activation of complement and macrophages. This suggests a potential role to treat ALI.

Macrophage-derived chemokine (CCL22) is a novel mediator of lung inflammation following hemorrhage and resuscitation

Resuscitation of patients after hemorrhage often results in pulmonary inflammation and places them at risk for the development of acute respiratory distress syndrome. Our previous data indicate that macrophage-derived chemokine (MDC/CCL22) is elevated after resuscitation, but its direct role in this inflammatory response is unknown. Macrophage-derived chemokine signaling through the C-C chemokine receptor type 4 (CCR4) is implicated in other pulmonary proinflammatory conditions, leading us to hypothesize that MDC may also play a role in the pathogenesis of lung inflammation following hemorrhage and resuscitation. To test this, C57BL/6 mice underwent pressure-controlled hemorrhage followed by resuscitation with lactated Ringer's solution. Pulmonary inflammation and inflammatory cell recruitment were analyzed with histological staining, and serum- and tissue-level cytokines were measured by enzyme-linked immunosorbent assay. Pulmonary inflammation and cell recruitment following hemorrhage and resuscitation were associated with systemic MDC levels. Inhibition of MDC via injection of a specific neutralizing antibody prior to hemorrhage and resuscitation significantly reduced pulmonary levels of the chemotactic cytokines keratinocyte-derived chemokine and macrophage inflammatory proteins 2 and 1α, as well as inflammatory cell recruitment to the lungs. Intravenous administration of recombinant MDC prior to resuscitation augmented pulmonary inflammation and cell recruitment. Histological evaluation revealed the expression of CCR4 within the bronchial epithelium, and in vitro treatment of activated bronchial epithelial cells with MDC resulted in production and secretion of neutrophil chemokines. The present study identifies MDC as a novel mediator of lung inflammation after hemorrhage and resuscitation. Macrophage-derived chemokine neutralization may provide a therapeutic strategy to mitigate this inflammatory response.