Circulating IL-6 mediates lung injury via CXCL1 production after acute kidney injury in mice

Serum IL-6 is increased in patients with acute kidney injury (AKI) and is associated with prolonged mechanical ventilation and increased mortality. Inhibition of IL-6 in mice with AKI reduces lung injury associated with a reduction in the chemokine CXCL1 and lung neutrophils. Whether circulating IL-6 or locally produced lung IL-6 mediates lung injury after AKI is unknown. We hypothesized that circulating IL-6 mediates lung injury after AKI by increasing lung endothelial CXCL1 production and subsequent neutrophil infiltration. To test the role of circulating IL-6 in AKI-mediated lung injury, recombinant murine IL-6 was administered to IL-6-deficient mice. To test the role of CXCL1 in AKI-mediated lung injury, CXCL1 was inhibited by use of CXCR2-deficient mice and anti-CXCL1 antibodies in mice with ischemic AKI or bilateral nephrectomy. Injection of recombinant IL-6 to IL-6-deficient mice with AKI increased lung CXCL1 and lung neutrophils. Lung endothelial CXCL1 was increased after AKI. CXCR2-deficient and CXCL1 antibody-treated mice with ischemic AKI or bilateral nephrectomy had reduced lung neutrophil content. In summary, we demonstrate for the first time that circulating IL-6 is a mediator of lung inflammation and injury after AKI. Since serum IL-6 is increased in patients with either AKI or acute lung injury and predicts prolonged mechanical ventilation and increased mortality in both conditions, our data suggest that serum IL-6 is not simply a biomarker of poor outcomes but a pathogenic mediator of lung injury.     

Biglycan-triggered TLR-2- and TLR-4-signaling exacerbates the pathophysiology of ischemic acute kidney injury

Exacerbated inflammation in renal ischemia–reperfusion injury, the major cause of intrinsic acute renal failure, is a key trigger of kidney damage. During disease endogenous danger signals stimulate innate immune cells via Toll-like receptors (TLR)-2 and -4 and accelerate inflammatory responses. Here we show that production of soluble biglycan, a small leucine-rich proteoglycan, is induced during reperfusion and that it functions as endogenous agonist of TLR-2/4. Biglycan-mediated activation of TLR-2/4 initiates an inflammatory response in native kidneys, which is marked by the release of cytokines and chemokines and recruitment of inflammatory cells. Overexpression of soluble circulating biglycan before ischemic reperfusion enhanced plasma and renal levels of TNF-α, CXCL1, CCL2 and CCL5, caused influx of neutrophils, macrophages and T cells and overall worsened renal function in wild type mice. We provide robust genetic evidence for TLR-2/4 requirement insofar as biglycan biological effects were markedly dampened in mice deficient in both innate immune receptors, Tlr2^−/−;Tlr4^−/− mice. Thus, signaling of soluble biglycan via TLR-2/4 could represent a novel therapeutic target for the prevention and possible treatment of patients with acute renal ischemia–reperfusion injury.     

Macrophages mediate lung inflammation in a mouse model of ischemic acute kidney injury

Serum IL-6 is increased in acute kidney injury (AKI) and inhibition of IL-6 reduces AKI-mediated lung inflammation. We hypothesized that circulating monocytes produce IL-6 and that alveolar macrophages mediate lung inflammation after AKI via chemokine (CXCL1) production. To investigate systemic and alveolar macrophages in lung injury after AKI, sham operation or 22 min of renal pedicle clamping (AKI) was performed in three experimental settings: 1) systemic macrophage depletion via diphtheria toxin (DT) injection to CD11b-DTR transgenic mice, 2) DT injection to wild-type mice, and 3) alveolar macrophage depletion via intratracheal (IT) liposome-encapsulated clodronate (LEC) administration to wild-type mice. In mice with AKI and systemic macrophage depletion (CD11b-DTR transgenic administered DT) vs. vehicle-treated AKI, blood monocytes and lung interstitial macrophages were reduced, renal function was similar, serum IL-6 was increased, lung inflammation was improved, lung CXCL1 was reduced, and lung capillary leak was increased. In wild-type mice with AKI administered DT vs. vehicle, serum IL-6 was increased. In mice with AKI and alveolar macrophage depletion (IT-LEC) vs. AKI with normal alveolar macrophage content, blood monocytes and lung interstitial macrophages were similar, alveolar macrophages were reduced, renal function was similar, lung inflammation was improved, lung CXCL1 was reduced, and lung capillary leak was increased. In conclusion, administration of DT in AKI is proinflammatory, limiting the use of the DTR-transgenic model to study systemic effects of AKI. Mice with AKI and either systemic mononuclear phagocyte depletion or alveolar macrophage depletion had reduced lung inflammation and lung CXCL1, but increased lung capillary leak; thus, mononuclear phagocytes mediate lung inflammation, but they protect against lung capillary leak after ischemic AKI. Since macrophage activation and chemokine production are key events in the development of acute lung injury (ALI), these data provide further evidence that AKI may cause ALI.     

Expression of CD44 in kidney after acute ischemic injury in rats

De novo CD44 and ligand expression at wound margins accompanies cellular proliferation and migration that effect repair of injured mucosal and vascular endothelial tissues. To determine whether CD44 could play a role in recovery from acute ischemic renal injury, we characterized its renal expression and those of two of its ligands, hyaluronic acid and osteopontin. Although no expression is detectable in nonischemic kidneys, several mRNAs for CD44 are present within 1 day after injury. CD44 mRNA is expressed in proximal tubules undergoing repair. CD44 peptide is present in basal and lateral cell membranes. Hyaluronic acid is normally expressed in the interstitium of the renal papilla only. By 1 day postischemia, hyaluronic acid can be detected, in addition, in the interstitium surrounding regenerating tubules. Osteopontin, not normally expressed in the renal proximal tubule, is expressed in regenerating tubules by 3 days after induction of acute ischemic injury. Immunoreactive osteopontin peptide continues to be localized in those tubules still undergoing repair for as long as 7 days after the injury. Our data are consistent with a role for CD44-ligand interactions in the regenerating proximal tubule participating in the process of recovery after ischemic injury.     

Nitroxyl exacerbates ischemic cerebral injury and oxidative neurotoxicity

Nitroxyl (HNO) donor compounds function as potent vasorelaxants, improve myocardial contractility and reduce ischemia-reperfusion injury in the cardiovascular system. With respect to the nervous system, HNO donors have been shown to attenuate NMDA receptor activity and neuronal injury, suggesting that its production may be protective against cerebral ischemic damage. Hence, we studied the effect of the classical HNO-donor, Angeli's salt (AS), on a cerebral ischemia/reperfusion injury in a mouse model of experimental stroke and on related in vitro paradigms of neurotoxicity. I.p. injection of AS (40 μmol/kg) in mice prior to middle cerebral artery occlusion exacerbated cortical infarct size and worsened the persistent neurological deficit. AS not only decreased systolic blood pressure, but also induced systemic oxidative stress in vivo indicated by increased isoprostane levels in urine and serum. In vitro , neuronal damage induced by oxygen-glucose-deprivation of mature neuronal cultures was exacerbated by AS, although there was no direct effect on glutamate excitotoxicity. Finally, AS exacerbated oxidative glutamate toxicity – that is, cell death propagated via oxidative stress in immature neurons devoid of ionotropic glutamate receptors. Taken together, our data indicate that HNO might worsen cerebral ischemia-reperfusion injury by increasing oxidative stress and decreasing brain perfusion at concentrations shown to be cardioprotective in vivo .     

Oxygenation inhibits the physiological tissue-protecting mechanism and thereby exacerbates acute inflammatory lung injury

Acute respiratory distress syndrome (ARDS) usually requires symptomatic supportive therapy by intubation and mechanical ventilation with the supplemental use of high oxygen concentrations. Although oxygen therapy represents a life-saving measure, the recent discovery of a critical tissue-protecting mechanism predicts that administration of oxygen to ARDS patients with uncontrolled pulmonary inflammation also may have dangerous side effects. Oxygenation may weaken the local tissue hypoxia-driven and adenosine A_2A receptor (A_2AR)-mediated anti-inflammatory mechanism and thereby further exacerbate lung injury. Here we report experiments with wild-type and adenosine A_2AR-deficient mice that confirm the predicted effects of oxygen. These results also suggest the possibility of iatrogenic exacerbation of acute lung injury upon oxygen administration due to the oxygenation-associated elimination of A_2AR-mediated lung tissue-protecting pathway. We show that this potential complication of clinically widely used oxygenation procedures could be completely prevented by intratracheal injection of a selective A_2AR agonist to compensate for the oxygenation-related loss of the lung tissue-protecting endogenous adenosine. The identification of a major iatrogenic complication of oxygen therapy in conditions of acute lung inflammation attracts attention to the need for clinical and epidemiological studies of ARDS patients who require oxygen therapy. It is proposed that oxygen therapy in patients with ARDS and other causes of lung inflammation should be combined with anti-inflammatory measures, e.g., with inhalative application of A_2AR agonists. The reported observations may also answer the long-standing question as to why the lungs are the most susceptible to inflammatory injury and why lung failure usually precedes multiple organ failure.     

炎症与急性缺血性肾损伤

近年来研究发现细胞间黏附分子-1和单核细胞趋化蛋白-1等炎症因子、核因子-κB及中性粒细胞、单核/巨噬细胞等炎症细胞参与了急性缺血性肾损伤的发生发展,抑制急性缺血性肾损伤时肾脏的炎症反应具有保护肾脏作用.     

TNFR1-dependent pulmonary apoptosis during ischemic acute kidney injury

Despite advancements in renal replacement therapy, the mortality rate for acute kidney injury (AKI) remains unacceptably high, likely due to remote organ injury. Kidney ischemia-reperfusion injury (IRI) activates cellular and soluble mediators that incite a distinct pulmonary proinflammatory and proapoptotic response. Tumor necrosis factor receptor 1 (TNFR1) has been identified as a prominent death receptor activated in the lungs during ischemic AKI. We hypothesized that circulating TNF-α released from the postischemic kidney induces TNFR1-mediated pulmonary apoptosis, and we aimed to elucidate molecular pathways to programmed cell death. Using an established murine model of kidney IRI, we characterized the time course for increased circulatory and pulmonary TNF-α levels and measured concurrent upregulation of pulmonary TNFR1 expression. We then identified TNFR1-dependent pulmonary apoptosis after ischemic AKI using TNFR1-/- mice. Subsequent TNF-α signaling disruption with Etanercept implicated circulatory TNF-α as a key soluble mediator of pulmonary apoptosis and lung microvascular barrier dysfunction during ischemic AKI. We further elucidated pathways of TNFR1-mediated apoptosis with NF-κB (Complex I) and caspase-8 (Complex II) expression and discovered that TNFR1 proapoptotic signaling induces NF-κB activation. Additionally, inhibition of NF-κB (Complex I) resulted in a proapoptotic phenotype, lung barrier leak, and altered cellular flice inhibitory protein signaling independent of caspase-8 (Complex II) activation. Ischemic AKI activates soluble TNF-α and induces TNFR1-dependent pulmonary apoptosis through augmentation of the prosurvival and proapoptotic TNFR1 signaling pathway. Kidney-lung crosstalk after ischemic AKI represents a complex pathological process, yet focusing on specific biological pathways may yield potential future therapeutic targets.     

Susceptibility to ozone-induced acute lung injury in iNOS-deficient mice

Mice deficient in inducible nitric oxide synthase (iNOS; C57Bl/6Ai-[KO]NOS2 N5) or wild-type C57Bl/6 mice were exposed to 1 part/million of ozone 8 h/night or to filtered air for three consecutive nights. Endpoints measured included lavagable total protein, macrophage inflammatory protein (MIP)-2, matrix metalloproteinase (MMP)-9, cell content, and tyrosine nitration of whole lung proteins. Ozone exposure caused acute edema and an inflammatory response in the lungs of wild-type mice, as indicated by significant increases in lavage protein content, MIP-2 and MMP-9 content, and polymorphonuclear leukocytes. The iNOS knockout mice showed significantly greater levels of lung injury by all of these criteria than did the wild-type mice. We conclude that iNOS knockout mice are more susceptible to acute lung damage induced by exposure to ozone than are wild-type C57Bl/6 mice and that protein nitration is associated with the degree of inflammation and not dependent on iNOS-derived nitric oxide.     

Granisetron protects polymicrobial sepsis-induced acute lung injury in mice

Sepsis is a serious condition with a high mortality rate worldwide. Granisetron is an anti-nausea drug for patients undergoing chemotherapy. Here we aimed to identify the novel effect of granisetron on sepsis-induced acute lung injury (ALI). Our results showed that mice treated with granisetron displayed less severe lung damage than controls. Granisetron administration reduced pulmonary neutrophil recruitment after CLP. Moreover, the expressions of Cxcl1 and Cxcl2 were diminished in the presence of granisetron in THP-1 macrophages after lipopolysaccharide exposure. Additionally, granisetron could inhibit the activation of p38 MAPK and NLRP3 inflammasome both in vivo and in vitro. Collectively, granisetron protects against sepsis-induced ALI by suppressing macrophage Cxcl1/Cxcl2 expression and neutrophil recruitment in the lung.     

高密度脂蛋白减轻小鼠内毒素性急性肺损伤

高密度脂蛋白(high density lipoprotein, HDL)是一种血浆含量丰富的脂蛋白,通常认为它可在体内发挥抗炎作用,能够与内毒素结合而抑制其生物活性.为探讨人HDL对内毒素性急性肺损伤的影响,将昆明小鼠分为假手术对照组、脂多糖(lipopolysaccharide, LPS)组、HDL组和LPS HDL组,腹腔注射LPS(10mg/kg体重)复制内毒素性急性肺损伤模型,于腹腔注射LPS 30min后经尾静脉给予人血浆HDL(70mg/kg体重),6h后结束实验.处死动物前抽取动脉血测定血气变化(PaO2, pH, PaCO2).处死后行支气管肺泡灌洗,计数灌洗液中白细胞(white blood cell, WBC)数量,测定蛋白含量和乳酸脱氢酶(lactate dehydrogenase, LDH)活性,并取肺组织进行病理学观察,测定肺组织湿/干重比值、丙二醛(malondialdehyde, MDA)含量、髓过氧化酶(myeloperoxidase, MPO)活性和肿瘤坏死因子-α(tumor necrosis factor α, TNF-α)含量.结果显示:(1)HDL改善小鼠肺换气功能,显著降低LPS所致的PaO2、pH的降低和PaCO2的增高(P<0.01);(2)HDL显著抑制LPS所致的肺泡灌洗液中WBC数量、总蛋白浓度和LDH活性的增高(P<0.01),降低肺组织湿/干重比值、MPO活性、MDA和TNF-α含量(P<0.05, P<0.01);(3)病理形态学分析及评分显示,HDL治疗组小鼠在出血、肺水肿及肺组织内中性粒细胞浸润的程度均低于LPS所致肺损伤组(P<0.01).结果提示,HDL可减轻小鼠内毒素性急性肺损伤.     

Genetic susceptibility to irritant-induced acute lung injury in mice

Recent studies suggest that genetic variability can influence irritant-induced lung injury and inflammation. To begin identifying genes controlling susceptibility to inhaled irritants, seven inbred mouse strains were continuously exposed to nickel sulfate (NiSO(4)), polytetrafluoroethylene, or ozone (O(3)), and survival time was recorded. The A/J (A) mouse strain was sensitive, the C3H/He (C3) strain was intermediate, and the C57BL/6 (B6) strain was resistant to NiSO(4)-induced acute lung injury. The B6AF(1) offspring were also resistant. The strain sensitivity pattern for NiSO(4) exposure was similar to that of polytetrafluoroethylene or ozone (O(3)). Pulmonary pathology was comparable for A and B6 mice. In the A strain, 15 microg/m(3) of NiSO(4) produced 20% mortality. The strain sensitivity patterns for lavage fluid proteins (B6 > C3 > A) and neutrophils (A >/= B6 > C3) differed from those for acute lung injury. This phenotype discordance suggests that these traits are not causally linked (i.e., controlled by independent arrays of genes). As in acute lung injury, B6C3F(1) offspring exhibited phenotypes (lavage fluid proteins and neutrophils) resembling those of the resistant parental strain. Agreement of acute lung injury strain sensitivity patterns among irritants suggested a common mechanism, possibly oxidative stress, and offspring resistance suggested that sensitivity is inherited as a recessive trait.     

Important role of apoptosis signal-regulating kinase 1 in ischemic acute kidney injury

We investigated the role of apoptosis signal-regulating kinase 1 (ASK1) in ischemia/reperfusion (I/R)-induced acute kidney injury (AKI). Blood urea nitrogen (BUN) and serum creatinine were significantly higher in ASK1+/+ mice than in ASK1−/− mice after I/R injury. Renal histology of ASK1+/+ mice showed significantly greater tubular necrosis and degradation. In ASK1−/− mice, phosphorylation of ASK1, JNK, and p38K, and the number of TUNEL-positive cells and infiltrated leukocytes decreased after I/R injury. Apoptotic changes were significantly decreased in cultured renal tubular epithelial cells (TECs) from ASK1−/− mice under hypoxic condition. Transfection with dominant-active ASK1 induced apoptosis in TECs. Protein expression of monocyte chemoattractant protein-1 (MCP-1) was significantly weaker in ASK1−/− mice after I/R injury. Transfection with dominant negative-ASK1 significantly decreased MCP-1 production in TECs. These results demonstrated that ASK1 is activated in I/R-induced AKI, and blockage of ASK1 attenuates renal tubular apoptosis, MCP-1 expression, and renal function.     

Complement C5a exacerbates acute lung injury induced through autophagy-mediated alveolar macrophage apoptosis

Intestinal ischemia has a high mortality and often causes acute lung injury (ALI), which is a serious complication, and is accompanied by high mortality up to 40%. An intense local and systemic inflammation occurs during intestinal ischemia/reperfusion (IR)-induced lung injury resulting from activation of immune responses. It has been reported that one component of complement, C5a, is indispensable for the full development of IR-induced lung injury, whereas the detailed molecular mechanism remains to be elucidated. In this study, we found that intestinal IR induced ALI-like symptoms, and C5a receptor (C5aR) expression was upregulated in alveolar macrophages, which are resident macrophages in lung tissue and are important in pulmonary homeostasis. C5a produced during lung injury binds to C5aR in alveolar macrophages, initiates downstream signaling that promotes autophagy, leading to apoptosis of alveolar macrophages. Using Mφ-ATG5^−/− mice, in which the atg5 is deficient specifically in macrophages and autophagy is inhibited, we confirmed that in vivo C5a interacting with C5aR induced autophagy in alveolar macrophages, which promoted alveolar macrophage apoptosis. Further study indicated that autophagy was induced through C5aR-mediated degradation of bcl-2. Taken together, our results demonstrated that C5aR-mediated autophagy induced apoptosis in alveolar macrophages, disrupting pulmonary homeostasis and contributing to the development of ALI. This novel mechanism suggests new therapeutic potential of autophagy regulation in ALI.During diverse clinical procedures, transient ischemia and reperfusion, known as ischemia/reperfusion (IR) clinically, are found in organs or tissues, and cause intense inflammation, both locally and systemically,^{1, 2} which in turn leads to various types of injury, even multiple organ failure, contributing to high mortality. Acute lung injury (ALI) is a common outcome of IR, and usually occurs in patients with intestinal ischemia, leading to high mortality of 60–80%.³ In addition, ALI is a life-threatening complication associated with sepsis, pneumonia, trauma, and many other clinical conditions. Despite improvements in the management of critically ill patients, ALI mortality is approximately 40%, and survivors often do not return to a normal life.⁴ During the IR process, ischemia initiates a local inflammatory response, by releasing pro-inflammatory factors and activating/attracting inflammatory cells, such as neutrophils, macrophages, and lymphocytes.⁵ Oxidative stress resulting from ischemia also contributes to IR injury. Owing to the unique anatomic and physiological features, the lung is susceptible to IR injury through pro-inflammatory cytokines storm.⁶ Only a few pharmacologic treatment options are available for IR-induced ALI, which work by inhibiting inflammation or anti-oxidative effects.⁷ Obviously, more effort is needed to clarify the underlying pathophysiological mechanisms of ALI and find more efficient therapeutic methods.Macrophages are believed to derive from hematopoietic stem cells and are distributed all over the body. Macrophages are of vital importance in immune homeostasis, tissue remodeling, and biological events. Alveolar macrophages are resident lung macrophages, and present the first line of encountering inhaled substances.⁸ Alveolar macrophages have essential roles in maintaining pulmonary homeostasis, without pro-inflammatory effects.⁹ More importantly, alveolar macrophages suppress excessive inflammation, putatively through the strong inhibition of local immune cells, such as T lymphocytes and DCs. For example, rodent alveolar macrophages render inhibition on T-cell activation in the presence of DCs in vitro, through multiple mechanisms, such as releasing the suppressive cytokines, transforming growth factor-β and interleukin-10 (IL-10).^{8, 9, 10, 11, 12} If alveolar macrophages are depleted, the animals display stronger inflammatory responses to otherwise innocuous inhaled antigens.¹³ During ALI, cytokines and chemokines produced by tissue macrophages recruit neutrophils to the injury sites,¹⁴ but the neutrophil recruitment also affects alveolar macrophage activity.^15,16 IL-10 production is induced by macrophages after phagocytosis of apoptotic neutrophils, which in turn suppresses additional cytokine production and inflammation, affecting both pro-inflammatory and anti-inflammatory cellular components of ALI.¹² For these reasons, alveolar macrophages have attracted interest in studies on the mechanisms of ALI.^{8, 9, 10, 11}Complements are key mediators of the first line in protecting hosts from pathogen invasions and have been shown to be involved in IR-induced inflammation. During the ignition and amplification stages, complement activation contributes to inflammation-mediated tissue injury,^{1, 2, 17} which would be significantly diminished if complement factors were depleted.^{18, 19} The complement activation product, C5a, is essential for the full development of injury. C5a has the ability of chemotaxis²⁰ and it can also directly activate neutrophils and macrophages for chemokine production.²¹ C5a receptor (C5aR) signaling is required for C5a to render its effects on the process, as blockade of C5aR signaling will have similar effects to depletion of C5a in the survival of animals with cecal ligation and puncture,²² suggesting that intercepting C5a or C5aR signaling may provide a potential target for therapeutic treatment in inflammatory diseases.²³Although significant effort has been aimed at determining the mechanism of macrophages in ALI, the activity of C5aR on macrophages is unclear. This study aimed to clarify the role of C5aR in macrophage biology during ALI development, and found that elevated C5a induced C5aR signaling in alveolar macrophages, and contributed to autophagy-mediated apoptosis, thus exacerbating the ALI symptoms. This novel mechanism provides a potential role for autophagy regulation in ALI therapeutic applications.     

Genetic deficiency of Smad3 protects against murine ischemic acute kidney injury

TGF-β1 contributes to chronic kidney disease, at least in part, via Smad3. TGF-β1 is induced in the kidney following acute ischemia, and there is increasing evidence that TGF-β1 may protect against acute kidney injury. As there is a paucity of information regarding the functional significance of Smad3 in acute kidney injury, the present study explored this issue in a murine model of ischemic acute kidney injury in Smad3(+/+) and Smad3(-/-) mice. We demonstrate that, at 24 h after ischemia, Smad3 is significantly induced in Smad3(+/+) mice, whereas Smad3(-/-) mice fail to express this protein in the kidney in either the sham or postischemic groups. Compared with Smad3(+/+) mice, and 24 h following ischemia, Smad3(-/-) mice exhibited greater preservation of renal function as measured by blood urea nitrogen (BUN) and serum creatinine; less histological injury assessed by both semiquantitative and qualitative analyses; markedly suppressed renal expression of IL-6 and endothelin-1 mRNA (but comparable expression of MCP-1, TNF-α, and heme oxygenase-1 mRNA); and no increase in plasma IL-6 levels, the latter increasing approximately sixfold in postischemic Smad3(+/+) mice. We conclude that genetic deficiency of Smad3 confers structural and functional protection against acute ischemic injury to the kidney. We speculate that these effects may be mediated through suppression of IL-6 production. Finally, we suggest that upregulation of Smad3 after an ischemic insult may contribute to the increased risk for chronic kidney disease that occurs after acute renal ischemia.     

Anti-inflammatory effects of anethole in lipopolysaccharide-induced acute lung injury in mice

Aims

Anethole, the major component of the essential oil of star anise, has been reported to have antioxidant, antibacterial, antifungal, anti-inflammatory, and anesthetic properties. In this study, we investigated the anti-inflammatory effects of anethole in a mouse model of acute lung injury induced by lipopolysaccharide (LPS).

Main methods

BALB/C mice were intraperitoneally administered anethole (62.5, 125, 250, or 500 mg/kg) 1 h before intratracheal treatment with LPS (1.5 mg/kg) and sacrificed after 4 h. The anti-inflammatory effects of anethole were assessed by measuring total protein and cell levels and inflammatory mediator production and by histological evaluation and Western blot analysis.

Key findings

LPS significantly increased total protein levels; numbers of total cells, including macrophages and neutrophils; and the production of inflammatory mediators such as matrix metalloproteinase 9 (MMP-9), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and nitric oxide (NO) in bronchoalveolar lavage fluid. Anethole (250 mg/kg) decreased total protein concentrations; numbers of inflammatory cells, including neutrophils and macrophages; and the inflammatory mediators MMP-9, TNF-α and NO. In addition, pretreatment with anethole decreased LPS-induced histopathological changes. The anti-inflammatory mechanism of anethole in LPS-induced acute lung injury was assessed by investigating the effects of anethole on NF-κB activation. Anethole suppressed the activation of NF-κB by blocking IκB-α degradation.

Significance

These results, showing that anethole prevents LPS-induced acute lung inflammation in mice, suggest that anethole may be therapeutically effective in inflammatory conditions in humans.