Acute respiratory distress syndrome: update on the latest developments in basic and clinical research

Protective effects and mechanisms of mogroside V on LPS-induced acute lung injury in mice

CONTEXT

Mogroside V, a compound isolated from Momordica grosvenori Swingle, which belongs to the Cucurbitaceae, is a traditional Chinese medicine reported to have anti-inflammatory potential in murine macrophages and a murine ear edema model.

OBJECTIVE

To investigate the effects and mechanisms of action of this compound in a model of acute lung injury (ALI) induced by lipopolysaccharides (LPS).

MATERIALS AND METHODS

Female BALB/c mice were treated with commercial mogroside V (2.5, 5 and 10 mg/kg) for 1 h prior to intranasal injection of LPS (10 μg in 50 μl). After 12 h, airway inflammation in the ALI model was determined by the wet/dry weight (W/D) ratio, myeloperoxidase (MPO) activity of lung tissue, leukocyte recruitment and cytokine levels in the bronchoalveolar lavage fluid (BALF). Additionally, lung tissue was examined by histology and western blotting to investigate the changes in pathology and the signalling in the presence and absence of mogroside V.

RESULTS

Mogroside V at 5 and 10 mg/kg inhibited airway inflammation induced by LPS as measured by the decrease in the histological changes (44 and 67.3% reduction in lung injury score, respectively), a 28.9 and 55.3% reduction in lung MPO activity, and inflammatory cell counts, interleukin-1β (IL-1β, 382 and 280 pg/ml, respectively), IL-6 (378 and 232 pg/ml, respectively) and tumor necrosis factor-α (TNF-α, 12.5 and 7.8 ng/ml, respectively) levels in the BALF. Additionally, mogroside V treatment reduced the activation of cyclooxygenase 2 (COX-2), inducible NO synthase (iNOS), and the nuclear factor (NF)-κB.

DISCUSSIONS AND CONCLUSIONS

Together, these data suggest that mogroside V has the potential to protect against LPS-induced airway inflammation in a model of ALI.

Indole-3-carbinol inhibits LPS-induced inflammatory response by blocking TRIF-dependent signaling pathway in macrophages

Indole-3-carbinol (I3C), a natural hydrolysis product of glucobrassicin, is a member of the Brassica family of vegetables and is known to have various anti-cancer activities. In the present study, we assessed in vitro and in vivo anti-inflammatory effects of I3C and its molecular mechanisms. I3C attenuated the production of pro-inflammatory mediators such as NO, IL-6, and IL-1β in LPS-induced Raw264.7 cells and THP-1 cells through attenuation of the TRIF-dependent signaling pathway. Furthermore, I3C suppressed the infiltration of immune cells into the lung and pro-inflammatory cytokine production such as IL-6, TNF-α in broncho-alveolar lavage fluid (BALF) in the LPS-induced acute lung injury mouse model. I3C also suppressed IL-1β secretion in nigericin treated in vivo model. I3C has potent anti-inflammatory effects through regulating TRIF-dependent signaling pathways, suggesting that I3C may provide a valuable therapeutic strategy in treating various inflammatory diseases.

Effect of safflor yellow injection on inhibiting lipopolysaccharide-induced pulmonary inflammatory injury in mice

OBJECTIVE

To observe the effect of Safflor Yellow (SY) Injection on acute lung injury (ALI) induced by lipopolysaccharide (LPS) in mice.

METHODS

Seventy-two mice were divided into six groups: control (saline + saline); LPS (LPS + saline); SY Injection [LPS + SY (10, 20 or 40 mg/kg, intravenously)] and anisodamine (AD) (LPS + AD). Thirty minutes after SY or AD administration, 15 mg/kg LPS was given intraperitoneally. All animals were sacrificed 4 h after LPS injection. Arterial blood gas and lung water content index (LWCI) were measured. Lung tissue myeloperoxidase (MPO) activity was assayed. mRNA expression of inflammatory cytokines was assayed by reverse-transcription polymerase chain reaction. Lung morphological and nuclear factor (NF)-κB p65-positive cell changes were observed by HE and immunohistochemical staining. p38 mitogen-activated protein kinase (MAPK) phosphorylation was observed by Western blotting.

RESULTS

After LPS administration, all animals displayed increased arterial carbon dioxide partial pressure (PaCO2) and decreased arterial oxygen partial pressure (PaO2), arterial oxygen saturation (SO2), HCO3 (-) concentration and pH, and increased LWCI, MPO activity, interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α mRNA expression, NF-κB p65-positive staining and p38 MAPK activation compared with normal controls (all P<0.01). SY Injection significantly mitigated the LPS-induced increase in arterial PaCO and the decreases in arterial PaO2, SO2 and pH, and attenuated increases in LWCI and lung tissue MPO activity (all P<0.01). Moreover, SY Injection inhibited the increases in NF-κB p65 staining and in TNF-α, IL-1β and IL-6 mRNA expression (all P<0.01), and promoted the expression of the antiinflammatory cytokine IL-10 (P<0.05) following LPS injection. LPS-induced pulmonary p38 MAPK phosphorylation was suppressed by pretreatment with SY Injection (P<0.01).

CONCLUSION

SY Injection ameliorates inflammatory ALI induced by LPS in mice.

The effect of HMGB1 A box on lung injury in mice with acute pancreatitis

The objective of this study is to observe the effect of high-mobility group protein B1 A Box (HMGB1 A) box on lung injury in mice with acute pancreatitis and its effect on the level of high-mobility group protein B1 (HMGB1) in lung, to explore the mechanism. A total of 60 male Institute of Cancer Research mice were randomly divided into control group (n = 30) and treatment group (n = 30). Severe acute pancreatitis mice model was induced by 20% L-Arg intraperitoneal injection. The recombination HMGB1 A box was used in treatment after modeling. All the mice were killed under anesthesia at 24 and 48 h after the modeling injection. The level of HMGB1 and activity of myeloperoxidase (MPO) in lung were measured. The pathological changes of lung were observed. The level of HMGB1 in lung of A box treatment group decreased more significantly 24 h and 48 h after modeling compared with control group. The activity of MPO in lung of A box treatment group decreased more significantly 24 h after modeling compared with control group. The lung tissue pathologic score of A box treatment group decreased more significantly 48 h after modeling compared with control group. HMGB1 expression levels in the lungs were positively related to histological score of injured lung in acute pancreatitis. It indicates that HMGB1 A box is remarkably protective to lung injury induced by acute pancreatitis.

Preventive effects of valnemulin on lipopolysaccharide-induced acute lung injury in mice

Valnemulin reportedly regulates inflammatory responses in addition to its in vitro antibacterial activity. In this study, we established a mouse model of lipopolysaccharide (LPS)-induced inflammatory lung injury and investigated the effect of valnemulin (100 mg/kg) on acute lung injury (ALI) 8 h after LPS challenge. We prepared bronchoalveolar lavage fluid (BALF) for measuring protein concentrations, cytokine levels, and superoxidase dismutase (SOD) activity, and collected lungs for assaying wet-to-dry weight (W/D) ratios, myeloperoxidase (MPO) activity, cytokine mRNA expression, and histological change. We found that the pre-administration of valnemulin significantly decreases the W/D ratio of lungs, protein concentrations, and the number of total cells, neutrophils, macrophages, and leukomonocytes, and histologic analysis indicates that valnemulin significantly attenuates tissue injury. Furthermore, valnemulin significantly increases LPS-induced SOD activity in BALF and decreases lung MPO activity as well. In addition, valnemulin also inhibits the production of tumor necrosis factor-alpha, interleukin-6, and interleukin-1beta, which is consistent with mRNA expression in lung. The results showed that valnemulin had a protective effect on LPS-induced ALI in mice.

Protective effect of antagonist of high-mobility group box 1 on lipopolysaccharide-induced acute lung injury in mice

We explored the effects of recombinant A-box (rA-box), a specific blockade for endogenous high mobility group box 1 (HMGB1) protein, on acute lung inflammation induced by lipopolysaccharide (LPS) in vivo. Acute lung injury (ALI) was produced successfully by intratracheal administration of LPS (10 microg/mouse) in male BALB/c mice. rA-box (0.3, 0.6 mg/mouse, i.p.) was administered 30 min prior to or 2 h after LPS exposure. Bronchoalveolar lavage fluid (BALF) was obtained to measure chemokines, proinflammatory cytokines, total cell counts and proteins at the indicated time points. It was found that rA-box caused a significant reduction in the total cells and neutrophils in BALF, a significant reduction in the W/D ratio and protein leakage at 24 h after LPS challenge. In addition, rA-box was also believed to have downregulated the expression of LPS-induced chemokines (keratinocyte-derived chemokine) and proinflammatory cytokines, including early mediator TNF-a and late mediator HMGB1. These findings confirm the significant protection of rA-box against LPS-induced ALI, and the effect mechanism of rA-box was associated with decreasing the expression of chemokines and proinflammatory cytokines.