The role of keratinocyte-derived chemokine in hemorrhage-induced acute lung injury in mice

Sulforaphane-Dependent Up-Regulation of NRF2 Activity Alleviates Both Systemic Inflammatory Response and Lung Injury After Hemorrhagic Shock/Resuscitation in Mice

ABSTRACT

Hemorrhagic shock/resuscitation (HS/R) is closely associated with overwhelming oxidative stress and systemic inflammation. As an effective activator of the nuclear factor-erythroid factor 2 related factor 2 (Nrf2) pathway, sulforaphane (SFN) exerts antioxidant and anti-inflammatory effects. We explored SFN's effects on alveolar macrophages (AMs), systemic inflammation, and pulmonary damage in an isolated murine HS/R model. Male C57/BL6 wild type and transgenic antioxidant response element (ARE)-luciferase (luc) mice (both n = 6 per group) were exposed to either pressure-controlled HS/R (mean arterial pressure 35-45 mm Hg for 90 min) or sham procedure (surgery without HS/R) or were sacrificed without intervention (control group). Fluid resuscitation was performed via the reinfusion of withdrawn blood and 0.9% saline. Sulforaphane or 0.9% saline (vehicle) was administrated intraperitoneally. Mice were sacrificed 6, 24, or 72 h after resuscitation. Bioluminescence imaging of ARE-luc mice was conducted to measure pulmonary Nrf2 activity. Plasma was collected to determine systemic cytokine levels. Alveolar macrophages were isolated before measuring cytokines in the supernatant and performing immunofluorescence staining, as well as Western blot for intracellular Nrf2. Histological damage was assessed via the acute lung injury score and wet/dry ratio.Hemorrhagic shock/resuscitation was associated with pulmonary Nrf2 activation. Sulforaphane enhanced pulmonary Nrf2 activity and the Nrf2 activation of AM, while it decreased lung damage. Sulforaphane exerted down-regulatory effects on AM-generated and systemic pro-inflammatory mediators, while it did not have such effects on IL-10.In conclusion, SFN beneficially enhances pulmonary Nrf2 activity and promotes Nrf2 accumulation in AMs' nuclei. This may exert not only local protective effects but also systemic effects via the down-regulation of pro-inflammatory cytokines. The administration of Nrf2 activator post-HS/R may represent an innovative treatment strategy.

IFNγ and TNFα mediate CCL22/MDC production in alveolar macrophages after hemorrhage and resuscitation

Acute lung injury is a major complication of hemorrhagic shock and the required resuscitation with large volumes of crystalloid fluids and blood products. We previously identified a role of macrophage-derived chemokine (CCL22/MDC) pulmonary inflammation following hemorrhage and resuscitation. However, further details regarding the induction of CCL22/MDC and its precise role in pulmonary inflammation after trauma remain unknown. In the current study we used in vitro experiments with a murine alveolar macrophage cell line, as well as an in vivo mouse model of hemorrhage and resuscitation, to identify key regulators in CCL22/MDC production. We show that trauma induces expression of IFNγ, which leads to production of CCL22/MDC through a signaling mechanism involving p38 MAPK, NF-κB, JAK, and STAT-1. IFNγ also activates TNFα production by alveolar macrophages, potentiating CCL22/MDC production via an autocrine mechanism. Neutralization of IFNγ or TNFα with specific antibodies reduced histological signs of pulmonary injury after hemorrhage and reduced inflammatory cell infiltration into the lungs.

Alleviation of Acute Lung Injury in Rats with Sepsis by Resveratrol via the Phosphatidylinositol 3-Kinase/Nuclear Factor-Erythroid 2 Related Factor 2/Heme Oxygenase-1 (PI3K/Nrf2/HO-1) Pathway

Background

Resveratrol (Res) is a type of polyphenol found in many plants, which can protect important organs from the damage induced by sepsis. However, the exact mechanism of its protective effect has not been established. This study investigated the effect of Res on the PI3K/Nrf2/HO-1 signaling pathway in rats with sepsis-induced acute lung injury (ALI).

Material/Methods

Male Wistar rats were treated with 30 mg/kg Res by intraperitoneal administration for 1 hour immediately after cecal ligation and puncture. Levels of MIP-2, IL-18, and IL-10 in bronchoalveolar lavage fluid (BALF) were determined. Lung tissues were collected to measure the wet-to-dry (W/D) ratios, oxidative stress index, and lung injury scores. Expression levels of Akt, p-Akt, HO-1, Nrf-2, and active caspase-3 proteins were determined by western blotting; expression of HO-1 mRNA was determined by RT-PCR.

Results

Treatment with Res significantly decreased the levels of MIP-2 and IL-18 and increased IL-10 in the BALF of rats with sepsis-induced ALI. In addition, Res also effectively reduced the W/D lung weight ratio, lung injury score, and the levels of MDA (malondialdehyde) and 8-OHdG. Conversely, Res increased SOD (superoxide dismutase) activity in the lung tissue. Moreover, Res significantly induced higher HO-1 mRNA expression, upregulated HO-1 and Nrf-2 protein expression, and the phosphorylation of Akt in the lung tissue. In contrast, the levels of activated caspase-3 protein were decreased in Res-treated rats (P<0.05).

Conclusions

Res could inhibit inflammation, oxidative stress, and cell apoptosis to alleviate ALI in septic rats through the inhibition of the PI3K/Nrf2/HO-1 signaling pathway.

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.

Cobalt chloride attenuates oxidative stress and inflammation through NF-κB inhibition in human renal proximal tubular epithelial cells

We evaluated the effect of cobalt chloride (CoCl2) on TNF-α and IFN-γ-induced-inflammation and reactive oxygen species (ROS) in renal tubular epithelial cells (HK-2 cells). We treated HK-2 cells with CoCl2 before the administration of TNF-α/IFN-γ. To regulate hemeoxygenase-1 (HO-1) expression, the cells were treated CoCl2 or HO-1 siRNA. CoCl2 reduced the generation of ROS induced by TNF-α/IFN-γ. TNF-α/IFN-γ-treated-cells showed an increase in the nuclear translocation of phosphorylated NF-κBp65 protein, the DNA-binding activity of NF-κBp50 and NF-κB transcriptional activity and a decrease in IκBα protein expression. These changes were restored by CoCl2. We noted an intense increase in monocyte chemoattractant protein-1 (MCP-1) and regulated on activation normal T cell expressed and secreted (RANTES) production in TNF-α/IFN-γ-treated cells. We demonstrated that this effect was mediated through NF-κB signaling because an NF-κB inhibitor significantly reduced MCP-1 and RANTES production. CoCl2 effectively reduced MCP-1 and RANTES production. The expression of HO-1 was increased by CoCl2 and decreased by HO-1 siRNA. However, knockdown of HO-1 by RNA interference did not affect MCP-1 or RANTES production. We suggest that CoCl2 has a protective effect on TNF-α/IFN-γ-induced inflammation through the inhibition of NF-κB and ROS in HK-2 cells. However, CoCl2 appears to act in an HO-1-independent manner.

Abnormal expression of Toll-like receptor 4 is associated with susceptibility to ethanol-induced gastric mucosal injury in mice

BACKGROUND AND AIMS

Toll-like receptor 4 (TLR4) contributes to ethanol-induced gastric mucosal injury. This study aimed to determine its precise role in this pathogenic state and the related signaling pathway.

METHODS

Ethanol-induced gastric mucosal injury models were generated in TLR4(-/-) mice (C3H/HeJ: point mutation; C57BL/10ScNJ: gene deletion), their respective TLR4(+/+) wild-type counterparts, and heterozygous TLR4(+/-) mice. Lipopolysaccharide (LPS) or pyrrolidine dithiocarbamate (PDTC) was injected intraperitoneally 1 h or 30 min before ethanol administration. At 1 h post-ethanol treatment, gastric or serum specimens were evaluated.

RESULTS

Ethanol intra-gastric administration induced significant gastric mucosal injury in all mice, but the damaged area was larger in TLR4(-/-) mice. LPS preconditioning and up-regulated TLR4 expression led to significantly larger areas of gastric mucosal damage. Upon ethanol administration, TLR4(+/+), and not TLR4(-/-), mice showed significant increases in TLR4, myeloid differentiation factor 88 (MyD88), cytoplasmic high mobility group box 1 (HMGB1), and nuclear factor-kappa B p65 (NF-κB p65). PDTC pretreatment significantly attenuated the ethanol-induced gastric mucosal damaged areas, inhibited nuclear NF-κB p65 expression, and suppressed HMGB1 translocation out of the nucleus. In addition, PDTC pretreatment reduced ethanol-stimulated expression of the inflammatory modulators, interleukin-1β (IL-1β) and tumor necrosis factor-alpha (TNF-α), in serum.

CONCLUSIONS

Both deficient and excessive expression of TLR4 promotes ethanol-induced gastric mucosal injury. The underlying mechanism involves the MyD88/NF-κB signaling pathway and the HMGB1, TLR4 activator ligand. The increased expression of HMGB1 may lead to increased secretion and binding to TLR4, further stimulating the TLR4/MyD88/NF-κB signaling pathway and aggravating the ethanol-induced gastric mucosal injury.

Pharmacologic resuscitation decreases circulating cytokine-induced neutrophil chemoattractant-1 levels and attenuates hemorrhage-induced acute lung injury

BACKGROUND

Acute lung injury (ALI) is a complication of hemorrhagic shock (HS). Histone deacetylase inhibitors, such as valproic acid (VPA), can improve survival after HS; however, their effects on late organ injury are unknown. Herein, we have investigated the effects of HS and VPA treatment on ALI and circulating cytokines that may serve as biomarkers for the development of organ injury.

METHODS

Anesthetized Wistar-Kyoto rats (250-300 g) underwent 40% blood volume hemorrhage over 10 minutes followed by 30 minutes of unresuscitated shock and were treated with either VPA (300 mg/kg) or vehicle control. Blood samples were obtained at baseline, after shock, and before death (at 1, 4, and 20 hours; n = 3-4/timepoint/group). Serum samples were screened for possible biomarkers using a multiplex electrochemiluminescence detection assay, and results were confirmed using enzyme-linked immunosorbent assay (ELISA). In addition, lung tissue lysate was examined for chemokine and myeloperoxidase (MPO) levels as a marker for neutrophil infiltration and ALI. Lung cytokine-induced neutrophil chemoattractant-1 (CINC-1; a chemokine belonging to the interleukin-8 family that promotes neutrophil chemotaxis) mRNA levels were measured by real-time polymerase chain reaction studies.

RESULTS

Serum screening revealed that hemorrhage rapidly altered levels of circulating CINC-1. ELISA confirmed that CINC-1 protein was significantly elevated in the serum as early as 4 hours and in the lung at 20 hours after hemorrhage, without any significant changes in CINC-1 mRNA expression. Lung MPO levels were also elevated at both 4 and 20 hours after hemorrhage. VPA treatment attenuated these changes.

CONCLUSION

Hemorrhage resulted in the development of ALI, which was prevented with VPA treatment. Circulating CINC-1 levels rose rapidly after hemorrhage, and serum CINC-1 levels correlated with lung CINC-1 and MPO levels. This suggests that circulating CINC-1 levels could be used as an early marker for the subsequent development of organ inflammation and injury.

Damage control resuscitation decreases systemic inflammation after hemorrhage

BACKGROUND

Severe hemorrhagic shock and resuscitation initiates a dysfunctional systemic inflammatory response leading to end-organ injury. Clinical evidence supports the transfusion of high ratios of plasma and packed red blood cells (pRBCs) in the treatment of hemorrhagic shock. The effects of resuscitation with different ratios of fresh blood products on inflammation and organ injury have not yet been characterized.

MATERIALS AND METHODS

Mice underwent femoral artery cannulation and pressure-controlled hemorrhage for 60 min, then resuscitation with fresh plasma and pRBCs collected from donor mice. Plasma alone, pRBCs alone, and ratios of 2:1, 1:1, and 1:2 plasma:pRBCs were used for resuscitation strategies. Mice were sacrificed to determine biochemical and hematologic parameters, serum cytokine concentrations, tissue myeloperoxidase levels, and vascular permeability.

RESULTS

Compared with other resuscitation strategies, mice resuscitated with pRBCs alone exhibited increased hemoglobin levels, while other hematologic and biochemical parameters were not significantly different among groups. Compared with 1:1, mice resuscitated with varying ratios of plasma:pRBCs exhibited increased cytokine concentrations of KC, MIP-1α, and MIP-2, and increased intestinal and lung myeloperoxidase levels. Mice resuscitated with 1:1 had decreased vascular permeability in the intestine and lung as compared with other groups.

CONCLUSIONS

Resuscitation with a 1:1 ratio of fresh plasma:pRBCs results in decreased systemic inflammation and attenuated organ injury. These findings support the potential advantage of transfusing blood products in physiologic ratios to improve the treatment of severe hemorrhagic shock.

Cyptoporus polysaccharide prevents lipopolysaccharide-induced acute lung injury associated with down-regulating Toll-like receptor 2 expression

AIM OF THE STUDY

To evaluate the effects and the possible mechanism of Cryptoporus polysaccharides (CP) extracted from fruiting body of Cryptoporus volvatus in lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats and mice.

MATERIALS AND METHODS

Acute lung injury was induced by intratracheally instillation of LPS into lung in either rats or mice, assessing leukocyte numbers and myeloperoxidase activity in bronchoalveolar lavage fluid, as well as evaluating cytokines mRNA and protein expressions, and Toll-like receptor 2 (TLR(2)) and nuclear factor (NF)-κB mRNA levels in the lung tissues of mice. Vascular permeability and edema of lung in mice, and arterial blood gas in rats were also performed.

RESULTS

In ALI, CP-treated mice and rats exhibited significantly reduced leukocyte invasion, myeloperoxidase activity, vascular permeability, edema of lung, as well as tumor necrosis factor-α and Interleukin-1β mRNA and protein expressions in the lung tissues compared with vehicle-treated mice. TLR(2) and NF-κB mRNA levels of the lung tissues were decreased in CP-treated mice in response to LPS. And decline in arterial blood gas was recovered in CP-treated rats.

CONCLUSIONS

Our results supported a protective role of CP in ALI and suggested that the reduction of the activation of TLR(2) and NF-κB signal pathway in lung injury may be relavant to the pretreatment of CP.