Effect of Toll-like receptor 4 inhibitor on LPS-induced lung injury

Qing-Fei-Pai-Du-Tang ameliorates lipopolysaccharide-induced rat acute lung injury through attenuating pulmonary microcirculatory disturbances via multi-target regulation

BACKGROUND

Acute lung injury (ALI) rapidly progressing into acute respiratory distress syndrome (ARDS) is a major cause of the high fatality rate in acute respiratory infectious diseases. Qing-Fei-Pai-Du-Tang (QFPDT) has a clinical advantage in ALI/ARDS treatment. However, whether QFPDT can improve multiple pathological process involved in pulmonary microcirculatory disturbances during ALI, and the underlying mechanisms remain unclear.

PURPOSE

The present study aimed to assess the role of QFPDT in a lipopolysaccharide (LPS)-induced ALI rat model, attempting to disclose the rationale behind the effects of QFPDT.

METHODS

Male Wistar rats were intraperitoneally injected with LPS (7.5 mg/kg), and received QFPDT (6 g/kg) by gavage either 10 min before (pre-treatment) or 6 hours after (post-treatment) LPS injection. Intravital microscopy, histology, immunohistochemistry and immunofluorescence, flow cytometry, enzyme-linked immunosorbent assay, Western blotting, and proteomics analysis were utilized to investigate the effects and mechanisms of QFPDT. Chemical profiling of QFPDT was performed to identify potential active ingredients.

RESULTS

The results revealed that 6 and 24 hours after LPS injection induced a hyper-inflammatory and hyperpermeability process in rat lung tissues. Pre- and post-treatment with QFPDT attenuated the increase in leukocyte adhesion to pulmonary venules, accompanied by high expression of CD11b and intercellular adhesion molecule-1. Besides, QFPDT attenuated the LPS-induced increase in fluorescein isothiocyanate-dextran leakage from pulmonary microvessels, along with a downregulated expression of junction proteins and an upregulated expression and phosphorylation of Caveolin-1. Moreover, there was a downregulated expression of basement membrane proteins, increased matrix metalloproteinase-9 and cleaved Cathepsin B, and decreased ATP/ADP and ATP/AMP ratios after LPS, all of which were attenuated by QFPDT. Proteomics data evaluated by gene set enrichment analysis, QFPDT pharmacokinetic analysis, combined with molecular docking prediction and surface plasmon resonance validation revealed that QFPDT contained lung-entering prototype ingredients that improved ALI by regulating various key signaling pathway proteins associated with leukocyte adhesion, microvascular hyperpermeability, basement membrane degradation, and oxidative stress.

CONCLUSION

The present study demonstrates the multifaceted effects of QFPDT and offers insight into better understanding its underlying mechanisms in attenuating LPS-induced pulmonary microcirculatory disturbances and lung dysfunction through a multi-component and multi-target mode, thereby providing evidence supporting the application of QFPDT in ALI/ARDS-related diseases.

Tetrastigma hemsleyanum polysaccharide protects against "two-hit" induced severe pneumonia via TLR4/NF-κB signaling pathway

Severe pneumonia, frequently accompanied by cytokine storms, stands as a perilous respiratory condition with alarmingly high mortality rates. Tetrastigma hemsleyanum polysaccharide (THP), a pivotal constituent derived from Tetrastigma hemsleyanum Diels et Gilg (TH), has demonstrated efficacy in treating lung inflammation. However, its precise efficacy and underlying mechanisms in the context of severe pneumonia remain elusive. Our research aims to elucidate THP's protective effects in a "two-hit" severe pneumonia model. Our observations indicate that THP administration markedly shields the lungs from injury, reduces pulmonary apoptosis, balances the formation of immune thrombus and alleviates oxidative stress in pneumonia-induced mice. Furthermore, THP significantly decreases the levels of pro-inflammatory cytokines, suggesting its robust anti-inflammatory capabilities. Notably, THP also plays a crucial role in normalizing gut microbiota imbalance, which is vital in the pathogenesis of severe pneumonia. Metabolomic analysis further validates THP's restorative effects on plasma metabolites, indicating its involvement in regulating energy metabolism and immune homeostasis. Mechanistically, THP targets the TLR4/NF-κB signaling pathway, a core mediator of inflammation, thereby dampening the inflammatory cascade. In summary, our findings underscore that THP, through its multifaceted actions targeting inflammation, oxidative stress, immune thrombus formation, gut microbiota regulation, and metabolic modulation, emerges as a promising therapeutic approach for severe pneumonia. This study provides invaluable insights into the potential applications of natural polysaccharides in treating severe pneumonia and highlights the significance of the TLR4/NF-κB pathway in the disease's progression.

Capsaicin Attenuates LPS-Induced Acute Lung Injury by Inhibiting Inflammation and Autophagy Through Regulation of the TRPV1/AKT Pathway

Purpose

Acute lung injury (ALI) is a severe pulmonary disease characterized by damage to the alveoli and pulmonary blood vessels, leading to severe impairment of lung function. Studies on the effect of capsaicin (8-methyl-N-geranyl-6-nonamide, CAP) on lipopolysaccharide (LPS)-induced ALI in bronchial epithelial cells transformed with Ad12-SV40 2B (BEAS-2B) are still limited. This study aimed to investigate the effect and specific mechanism by which CAP improves LPS-induced ALI.

Methods

The present study investigated the effect of CAP and the potential underlying mechanisms in LPS-induced ALI in vitro and vivo via RNA sequencing, Western blotting (WB), quantitative real-time reverse transcription PCR (qRT‒PCR), enzyme-linked immunosorbent assay (ELISA), and transmission electron microscopy (TEM). The TRPV1 inhibitor AMG9810 and the AKT agonist SC79 were used to confirm the protective effect of the TRPV1/AKT axis against ALI. The autophagy agonist rapamycin (Rapa) and the autophagy inhibitors 3-methyladenine (3-MA) and bafilomycin A1 (Baf-A1) were used to clarify the characteristics of LPS-induced autophagy.

Results

Our findings demonstrated that CAP effectively suppressed inflammation and autophagy in LPS-induced ALI, both in vivo and in vitro. This mechanism involves regulation by the TRPV1/AKT signaling pathway. By activating TRPV1, CAP reduces the expression of P-AKT, thereby exerting its anti-inflammatory and inhibitory effects on pro-death autophagy. Furthermore, prior administration of CAP provided substantial protection to mice against ALI induced by LPS, reduced the lung wet/dry ratio, decreased proinflammatory cytokine expression, and downregulated LC3 expression.

Conclusion

Taken together, our results indicate that CAP protects against LPS-induced ALI by inhibiting inflammatory responses and autophagic death through the TRPV1/AKT signaling pathway, presenting a novel strategy for ALI therapy.

Huangqin decoction mitigates hepatic inflammation in high-fat diet-challenged rats by inhibiting TLR4/NF-κB/NLRP3 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic hepatopathy worldwide, in which ectopic steatosis (5%) and inflammatory infiltration in the liver are the principal clinical characteristics. Huangqin decoction (HQD), a Chinese medicine formula used in the clinic for thousands of years, presents appreciable anti-inflammatory effects. Nevertheless, the role and mechanism of HQD against inflammation in NAFLD are still undefined.

AIM OF THE STUDY

The objective of this study was to evaluate the curative efficacy and unravel the involved mechanism of HQD on a high-fat diet (HFD)-induced NAFLD.

MATERIALS AND METHODS

First, HPLC was utilized to analyze the main chemical components of HQD. Then, NAFLD model was introduced by subjecting the rats to HFD for 16 weeks, and HQD (400 and 800 mg/kg) or polyene lecithin choline (PLC, 8 mg/kg) was given orally from week 8-16. Pharmacodynamic indicators including body weight, liver weight, liver index, as well as biochemical and histological parameters were assessed. As to mechanism exploration, the expressions of TLR4/NF-κB/NLRP3 pathway and molecular docking between major phytochemicals of HQD and key targets of TLR4/NF-κB/NLRP3 pathway were investigated.

RESULTS

Seven main monomeric constituents of HQD were revealed by HPLC analysis. Of note, HQD could effectively attenuate the body weight, liver weight, and liver index, rescue disorders in serum transaminases and lipid profile, correct hepatic histological abnormalities, and reduce phagocytes infiltration into the liver and pro-inflammatory cytokines release in NAFLD rats. Mechanism investigation discovered that HQD harbored inhibitory effects on TLR4/NF-κB/NLRP3 pathway-regulated liver inflammation. Further exploration found that seven phytochemicals in HQD exhibited better binding modes with TLR4/NF-κB/NLRP3 pathway, in which baicalein, baicalin and liquiritin presented the highest affinity and docking score for protein TLR4, NF-κB, and NLRP3, respectively.

CONCLUSIONS

These findings confirmed that HQD ameliorated hepatic inflammation in NAFLD rats by blocking the TLR4/NF-κB/NLRP3 pathway, with multi-components and multi-targets action pattern.

TLR4 is one of the receptors for Chikungunya virus envelope protein E2 and regulates virus induced pro-inflammatory responses in host macrophages

Toll like receptor 4 (TLR4), a pathogen-associated molecular pattern (PAMP) receptor, is known to exert inflammation in various cases of microbial infection, cancer and autoimmune disorders. However, any such involvement of TLR4 in Chikungunya virus (CHIKV) infection is yet to be explored. Accordingly, the role of TLR4 was investigated towards CHIKV infection and modulation of host immune responses in the current study using mice macrophage cell line RAW264.7, primary macrophage cells of different origins and in vivo mice model. The findings suggest that TLR4 inhibition using TAK-242 (a specific pharmacological inhibitor) reduces viral copy number as well as reduces the CHIKV-E2 protein level significantly using p38 and JNK-MAPK pathways. Moreover, this led to reduced expression of macrophage activation markers like CD14, CD86, MHC-II and pro-inflammatory cytokines (TNF, IL-6, MCP-1) significantly in both the mouse primary macrophages and RAW264.7 cell line, in vitro. Additionally, TAK-242-directed TLR4 inhibition demonstrated a significant reduction of percent E2-positive cells, viral titre and TNF expression in hPBMC-derived macrophages, in vitro. These observations were further validated in TLR4-knockout (KO) RAW cells. Furthermore, the interaction between CHIKV-E2 and TLR4 was demonstrated by immuno-precipitation studies, in vitro and supported by molecular docking analysis, in silico. TLR4-dependent viral entry was further validated by an anti-TLR4 antibody-mediated blocking experiment. It was noticed that TLR4 is necessary for the early events of viral infection, especially during the attachment and entry stages. Interestingly, it was also observed that TLR4 is not involved in the post-entry stages of CHIKV infection in host macrophages. The administration of TAK-242 decreased CHIKV infection significantly by reducing disease manifestations, improving survivability (around 75%) and reducing inflammation in mice model. Collectively, for the first time, this study reports TLR4 as one of the novel receptors to facilitate the attachment and entry of CHIKV in host macrophages, the TLR4-CHIKV-E2 interactions are essential for efficient viral entry and modulation of infection-induced pro-inflammatory responses in host macrophages, which might have translational implication for designing future therapeutics to regulate the CHIKV infection.

Oleocanthal alleviated lipopolysaccharide-induced acute lung injury in chickens by inhibiting TLR4/NF-κB pathway activation

This study aimed to investigate the ameliorative effect of oleocanthal (OC) on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in chickens and its possible mechanisms. In total, 20 chickens were randomly divided into 4 groups: control (CON) group, LPS group, LPS + OC group, and OC group. LPS + OC and OC groups were intragastrically administered a 5 mg/kg·d OC dose for 7 d. On d 8, the LPS group and LPS + OC group were intratracheally administered 2 mg/kg LPS for 12 h. It was found that OC ameliorated the pathological morphology and significantly suppressed apoptosis after OC treatment in LPS-induced ALI chicken (P < 0.01). Antioxidant capacity was higher in the LPS + OC group compared with the LPS group (P < 0.01). OC downregulated the related genes and proteins expression of toll-like receptor 4/nuclear factor-κB (TLR4/NF-κB) pathway in LPS group (P < 0.01). In conclusion, OC supplementation can alleviate LPS-induced ALI in chickens by suppressing apoptosis, enhancing lung antioxidant capacities and inhibiting TLR4/NF-κB pathway activation.

Asprosin Exerts Pro-Inflammatory Effects in THP-1 Macrophages Mediated via the Toll-like Receptor 4 (TLR4) Pathway

Adipose tissue is a dynamic endocrine organ, secreting a plethora of adipokines which play a key role in regulating metabolic homeostasis and other physiological processes. An altered adipokine secretion profile from adipose tissue depots has been associated with obesity and related cardio-metabolic diseases. Asprosin is a recently described adipokine that is released in response to fasting and can elicit orexigenic and glucogenic effects. Circulating asprosin levels are elevated in a number of cardio-metabolic diseases, including obesity and type 2 diabetes. In vitro studies have reported pro-inflammatory effects of asprosin in a variety of tissues. The present study aimed to further elucidate the role of asprosin in inflammation by exploring its potential effect(s) in THP-1 macrophages. THP-1 monocytes were differentiated to macrophages by 48 h treatment with dihydroxyvitamin D3. Macrophages were treated with 100 nM recombinant human asprosin, 100 ng/mL lipopolysaccharide (LPS), and 10 μM caffeic acid phenethyl ester (CAPE; an inhibitor of NFκB activation) or 1 µM TAK-242 (a Toll-like receptor 4, TLR4, inhibitor). The expression and secretion of pertinent pro-inflammatory mediators were measured by qPCR, Western blot, ELISA and Bioplex. Asprosin stimulation significantly upregulated the expression and secretion of the pro-inflammatory cytokines: tumour necrosis factor α (TNFα), interleukin-1β (IL-1β), IL-8 and IL-12 in vitro. This pro-inflammatory response in THP-1 macrophages was partly attenuated by the treatments with CAPE and was significantly inhibited by TAK-242 treatment. Asprosin-induced inflammation is significantly counteracted by TLR4 inhibition in THP-1 macrophages, suggesting that asprosin exerts its pro-inflammatory effects, at least in part, via the TLR4 signalling pathway.

Effects of the interaction of Notch and TLR4 pathways on inflammation and heart function in septic heart

We investigated the role of the interaction between the Notch and Toll-like receptor 4 (TLR4) pathways in septic myocardial injury. The sepsis model was induced in rats with lipopolysaccharide (LPS). Rats were divided into control, LPS, LPS + TAK242 ((6R)-6-[N-(2-chloro-4-fluorophenyl)sulfamoyl]cyclohex-1-ene-1-carboxylate) and LPS + DAPT (N-[N-(3,5-difluorophenacetyl)-l-alanyl]-s-phenylglycinetbutylester) groups. Heart function was evaluated with a Cardiac Doppler ultrasound. Myocardial morphological changes were detected by hematoxylin-eosin staining (H&E). Apoptosis was assessed by a TUNEL assay. The mRNA and protein levels were detected with real-time PCR, Western blot, and immunohistochemistry analysis. We found that heart function in the LPS + TAK242 group was significantly improved, but not in the LPS + DAPT group. LPS + TAK242 had a lower level of degeneration and necrosis of cardiomyocytes and inflammatory cell infiltration, as well as lower apoptosis and caspase-3 expression than the LPS group. Compared with the LPS group, the inflammatory cell infiltration was reduced in the LPS + DAPT group, while the degeneration and necrosis of cardiomyocytes were not obviously improved. Additionally, the expression levels of tumor necrosis factor-α and Interleukin-6, the protein contents of Notch intracellular domain and Hes1, and the P65 nuclear factor kappa-B (NF-κB) to P-P65 NF-κB ratio in LPS + TAK242 group and LPS + DAPT group were significantly lower than those in LPS group. Conclusively, the interaction between TLR4 and Notch signaling pathways enhances the inflammatory response in the septic heart by activating NF-κB. Blocking the TLR4 pathway with TAK242 can improve heart dysfunction and myocardial damage in sepsis, while blocking the Notch pathway with DAPT cannot effectively prevent heart dysfunction and myocardial damage in sepsis.

A Probe into the Intervention Mechanism of Yiqi Huayu Jiedu Decoction on TLR4/NLRP3 Signal Pathway in Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome (ARDS) Rats

Background

This study discusses the anti-inflammatory mechanism of Yiqi Huayu Jiedu decoction (YQHYJD) and studies the intervening effect of YQHYJD on the inflammatory cytokines in acute respiratory distress syndrome (ARDS) rats by inhibiting the TLR4/NLRP3 signal pathway. The aim of the probe is to provide evidence to support the identification of therapeutic targets in Chinese medicine treatment, which broadens the alternatives for the treatment of ARDS.

Method

A lipopolysaccharide (LPS)-induced ARDS model group is established on rats by tail vein injection. A medicine group is established on ARDS rats by prophylactic administration using YQHYJD. Materials are collected, and tests are conducted according to experimental processes.

Result

The rats in the medicine group gained weight compared with those in the ARDS model group. Pathological sections from the medicine group indicated improved condition in terms of pulmonary and interstitial edema in the lung tissues of rats compared with that from the ARDS model group. The percentage of neutrophil of the medicine group was significantly brought down compared with that of the ARDS model group (P < 0.001). Enzyme-linked immunosorbent assay (ELISA) was used to detect the changes in the level of inflammatory cytokines. It was observed that the levels of IL-1β and IL-18 in serum of the medicine group significantly decreased (P < 0.001 and P < 0.01), the contents of TLR4 and NLRP3 in bronchoalveolar lavage fluid (BALF) of the medicine group decreased, and the contents of TLR4 and NLRP3 in lung tissue homogenate of the medicine group significantly decreased (P < 0.05, P < 0.001, P < 0.01, and P < 0.05). In further mass spectrum identification of the proteins from the same animal groups, it was observed that the expressions of inflammatory proteins TNFRSF1, LBP, and NOS2 of the medicine group were reduced. The differences were statistically significant.

Conclusions

The pharmacological action of YQHYJD's anti-inflammatory mechanism is closely associated with the regulation of inflammatory cytokines TLR4, NLRP3, IL-1β, IL-18, TNFRSF1, LBP, and NOS2 on the TLR4/NLRP3 signal pathway.

Integrated Network Pharmacology and Experimental Validation Approach to Investigate the Therapeutic Effects of Capsaicin on Lipopolysaccharide-Induced Acute Lung Injury

An integrated method combining network pharmacology and in vivo experiment was performed to investigate the therapeutic mechanism of capsaicin (Cap) against acute lung injury. The potential key genes and signaling pathways involved in the therapeutic effect of Cap were predicted by the network pharmacology analyses. Additionally, the histological assessment, ELISA, and RT-qPCR were performed to confirm the therapeutic effect and the potential mechanism action involved. Our findings showed that TNF, IL-6, CXCL1, CXCL2, and CXCL10 were part of the top 50 genes. Enrichment analysis revealed that those potential genes were enriched in the TNF signaling pathway and IL-17 signaling pathway. In vivo experiment results showed that Cap alleviated histopathological changes, decreased inflammatory infiltrated cells and inflammatory cytokines, and improved antioxidative enzyme activities in the bronchoalveolar lavage fluid (BALF). Furthermore, Cap treatment effectively downregulated TNF, IL-6, NF-κB, CXCL1, CXCL2, and CXCL10 in lung tissue. Thus, our findings demonstrated that Cap has the therapeutic effect on LPS-induced acute lung injury in neonatal rats via suppression of the TNF signaling pathway and IL-17 signaling pathway.

Inhibition of toll-like receptor 4 protects against inflammation-induced mechanobiological alterations to intervertebral disc cells

Intervertebral disc (IVD) degeneration is associated with elevated levels of inflammatory cytokines implicated in disease aetiology and matrix degradation. Toll-like receptor-4 (TLR4) has been shown to participate in the inflammatory responses of the nucleus pulposus (NP) and its levels are upregulated in disc degeneration. Activation of TLR4 in NP cells leads to significant, persistent changes in cell biophysical properties, including hydraulic permeability and osmotically active water content, as well as alterations to the actin cytoskeleton. The study hypothesis was that inflammation-induced changes to cellular biomechanical properties and actin cytoskeleton of NP cells could be prevented by inhibiting TLR4 signalling. Isolated NP cells from bovine discs were treated with lipopolysaccharide (LPS), the best studied TLR4 agonist, with or without treatment with the TLR4 inhibitor TAK-242. Cellular volume regulation responses to step osmotic loading were measured and the transient volume-response was captured by time-lapse microscopy. Volume-responses were analysed using mixture theory framework to investigate hydraulic permeability and osmotically active intracellular water content. Hydraulic permeability and cell radius were significantly increased with LPS treatment and these changes were blocked in cells treated with TAK-242. LPS-induced remodelling of cortical actin and IL-6 upregulation were also mitigated by TAK-242 treatment. These findings indicated that TLR4 signalling participated in NP cell biophysical regulation and may be an important target for mitigating altered cell responses observed in IVD inflammation and degeneration.

Heme oxygenase-1 induction mitigates burn-associated early acute kidney injury via the TLR4 signaling pathway

OBJECTIVES

Early acute kidney injury (AKI) after burn contributes to disastrous prognoses for severely burned patients. Burn-induced renal oxidative stress and secondary proinflammatory mediator release contribute to early AKI development, and Toll-like receptor (TLR) 4 regulates inflammation. Heme oxygenase-1 (HO-1) is a stress-responsive enzyme that plays a vital role in protecting against ischemia-induced organ injury via its antioxidant properties and regulation of inflammation. We investigated the potential effect of HO-1 induction in preventing burn-induced early AKI and its related mechanism.

METHODS

A classic major-burn rat model was established using a 100 °C water bath, and hemin was injected intraperitoneally immediately after the injury to induce HO-1. Histological staining and blood tests were used to assess AKI progression based on structural changes and function. Renal levels of HO-1, oxidative stress, proinflammatory mediators and TLR4-related signals were detected using ELISA, immunostaining, qRT-PCR, and western blotting. The selective TLR4 inhibitor TAK242 and TLR4 inducer LPS were introduced to determine the roles of HO-1 in burn-related renal inflammation and the TLR4 pathway.

RESULTS

Hemin improved burn-induced renal histological damage and dysfunction, and this beneficial effect was related to reduced renal oxidative stress and the release of proinflammatory mediators, such as tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, IL-6 and intracellular adhesion molecule-1 (ICAM-1). Hemin downregulated the expression of TLR4 and the subsequent phosphorylation of IKKα/β, IκBα, and NF-κB p65;. TAK242 exerted an effect similar to but weaker than hemin; and LPS reversed the antiinflammatory effect of hemin and the regulation of TLR4 signals. These results suggested that the TLR4 signaling pathway mediated the HO-1-facilitated regulation of renal inflammation after burn.

CONCLUSION

The present study demonstrated that HO-1 induction prevented burn-induced early AKI by targeting renal inflammation, which was mediated via regulation of the TLR4/NF-κB signaling pathway.

COVID-19 and Toll-Like Receptor 4 (TLR4): SARS-CoV-2 May Bind and Activate TLR4 to Increase ACE2 Expression, Facilitating Entry and Causing Hyperinflammation

Causes of mortality from COVID-19 include respiratory failure, heart failure, and sepsis/multiorgan failure. TLR4 is an innate immune receptor on the cell surface that recognizes pathogen-associated molecular patterns (PAMPs) including viral proteins and triggers the production of type I interferons and proinflammatory cytokines to combat infection. It is expressed on both immune cells and tissue-resident cells. ACE2, the reported entry receptor for SARS-CoV-2, is only present on ~1-2% of the cells in the lungs or has a low pulmonary expression, and recently, the spike protein has been proposed to have the strongest protein-protein interaction with TLR4. Here, we review and connect evidence for SARS-CoV-1 and SARS-CoV-2 having direct and indirect binding to TLR4, together with other viral precedents, which when combined shed light on the COVID-19 pathophysiological puzzle. We propose a model in which the SARS-CoV-2 spike glycoprotein binds TLR4 and activates TLR4 signalling to increase cell surface expression of ACE2 facilitating entry. SARS-CoV-2 also destroys the type II alveolar cells that secrete pulmonary surfactants, which normally decrease the air/tissue surface tension and block TLR4 in the lungs thus promoting ARDS and inflammation. Furthermore, SARS-CoV-2-induced myocarditis and multiple-organ injury may be due to TLR4 activation, aberrant TLR4 signalling, and hyperinflammation in COVID-19 patients. Therefore, TLR4 contributes significantly to the pathogenesis of SARS-CoV-2, and its overactivation causes a prolonged or excessive innate immune response. TLR4 appears to be a promising therapeutic target in COVID-19, and since TLR4 antagonists have been previously trialled in sepsis and in other antiviral contexts, we propose the clinical trial testing of TLR4 antagonists in the treatment of severe COVID-19. Also, ongoing clinical trials of pulmonary surfactants in COVID-19 hold promise since they also block TLR4.

Echinacea polysaccharide alleviates LPS-induced lung injury via inhibiting inflammation, apoptosis and activation of the TLR4/NF-κB signal pathway

Lung injury is a common critical life-threatening syndrome. Inflammation is a key factor in the pathogenesis of lung injury. It is reported that Echinacea Polysaccharides (EP) has anti-inflammatory activity. However, the effect of EP on lung injury remains unclear. In our study, murine model of lung injury was induced with 2.5 mg/kg LPS before administration of 5 mg/kg or 10 mg/kg EP. EP ameliorated LPS-induced lung pathological damage, along with reduction in lung wet/dry weight ratio and myeloperoxidase activity. EP decreased the number of leukocytes, eosinophils, neutrophils, lymphocytes and macrophages in bronchoalveolar lavage fluid, and the release of tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) in LPS-treated lung. EP suppressed LPS-induced apoptosis along with down-regulation of Bcl2-associated X (Bax) and cleaved caspase-3 (CC3), and elevated B-cell lymphoma-2 (Bcl-2). Besides, RAW 264.7 cells were treated with EP 100 μg/ml for 1 h and then incubated with 1 μg/ml LPS for 24 h. TNF-α, IL-6 and IL-1β levels were lowered by treatment of EP in LPS-treated RAW 264.7 cells. Moreover, EP down-regulated the expression of toll-like receptor 4 (TLR4), myeloid differentiating factor 88 (MyD88), p-IκBα, nuclear factor kappa-B (NF-κB), p-NF-κB, and up-regulated the inhibitor of NF-κB (IκBα) in vivo and in vitro following LPS induction, which is consistent with the effect of TAK-242. In conclusion, EP may alleviate LPS-induced lung injury via inhibiting inflammation, apoptosis and activation of TLR4/NF-κB signal pathway.

TAK-242, a specific inhibitor of Toll-like receptor 4 signalling, prevents endotoxemia-induced skeletal muscle wasting in mice

Circulating lipopolysaccharide (LPS) concentrations are often elevated in patients with sepsis or various endogenous diseases related to bacterial translocation from the gut. Systemic inflammatory responses induced by endotoxemia induce severe involuntary loss of skeletal muscle, termed muscle wasting, which adversely affects the survival and functional outcomes of these patients. Currently, no drugs are available for the treatment of endotoxemia-induced skeletal muscle wasting. Here, we tested the effects of TAK-242, a Toll-like receptor 4 (TLR4)-specific signalling inhibitor, on myotube atrophy in vitro and muscle wasting in vivo induced by endotoxin. LPS treatment of murine C2C12 myotubes induced an inflammatory response (increased nuclear factor-κB activity and interleukin-6 and tumour necrosis factor-α expression) and activated the ubiquitin-proteasome and autophagy proteolytic pathways (increased atrogin-1/MAFbx, MuRF1, and LC-II expression), resulting in myotube atrophy. In mice, LPS injection increased the same inflammatory and proteolytic pathways in skeletal muscle and induced atrophy, resulting in reduced grip strength. Notably, pretreatment of cells or mice with TAK-242 reduced or reversed all the detrimental effects of LPS in vitro and in vivo. Collectively, our results indicate that pharmacological inhibition of TLR4 signalling may be a novel therapeutic intervention for endotoxemia-induced muscle wasting.

Effects of Tec Tyrosine Kinase Inhibition on the Inflammatory Response of Severe Acute Pancreatitis-Associated Acute Lung Injury in Mice

BACKGROUND

The Tec kinase family is involved in acute and chronic inflammatory diseases, but its relationship with severe acute pancreatitis (SAP) remains unclear.

AIMS

To investigate whether Tec tyrosine kinase can be used as a target for severe acute pancreatitis-associated acute lung injury (PALI).

METHODS

A total of 90 mice were randomly assigned into four groups: SAP (n = 15), control (n = 15), SAP + α-cyano-β-hydroxy-β-methyl-N-(2,5-dibromophenyl)propenamide (LFM-A13) (pretreated with Tec kinase inhibitor LFM-A13, n = 15), and SAP + Tec siRNA (pretreated with PBS/negative control siRNA/Tec siRNA, n = 45). SAP was induced by caerulein and lipopolysaccharide. Animals were sacrificed at 0, 3, 24, 48, and 72 h, respectively. Pathological changes and scores of the lung and pancreas were determined using hematoxylin-eosin staining. Expression of Tec and phosphorylated Tec (p-Tec) were examined by real-time polymerase chain reaction, Western blot, and immunoprecipitation. Serum levels of amylase, myeloperoxidase, and pro-inflammatory cytokines were measured by ELISA.

RESULTS

The expression of Tec in lung tissue was significantly higher in the SAP group than in the control group (p < 0.05), and p-Tec expression gradually increased with time. Furthermore, p-Tec expression was significantly lower in the SAP + LFM-A13 group than in the SAP group (p < 0.05); however, Tec expression did not vary. Tec inhibitors, LFM-A13 and Tec siRNA, alleviated pathological damage and release of inflammatory cytokines (p < 0.05).

CONCLUSIONS

Tec tyrosine kinase plays a key role in PALI, and is therefore a potential target for clinical treatment.

Network Pharmacology-Based Investigation of Protective Mechanism of Aster tataricus on Lipopolysaccharide-Induced Acute Lung Injury

Acute lung injury (ALI) is a common clinical condition that badly influences people's health. Recent studies indicated that Aster tataricus (RA) had potential effects on ALI, but the effective components and their mechanism is not clear. In this study, we found that the Fraction-75 eluted from RA extract could significantly protect the lipopolysaccharide (LPS)-induced ALI in mice, including alleviating the severity of lung pathology, attenuating the pulmonary edema, and reducing the release of inflammatory cells. Further ingredient analyses demonstrated that there were mainly 16 components in it, among which 10 components were collected according to their relative peak area and oral bioavailability. Next, the components-disease targets network suggested that the candidate components had extensive associations with 49 known therapeutic targets of ALI, among which 31 targets could be regulated by more than one component. Herein, GO functional and pathway analysis revealed that the common targets were associated with four biological processes, including the inflammatory response to stimulus, cellular process, chemokine biosynthetic process and immune system process. Furthermore, the ELISA validation indicated that the candidate components in RA extract may protect the LPS-induced ALI mainly through inhibiting the release of inflammatory cytokines and promoting the repair of vascular endothelial.

Naked pDNA Inhalation Powder Composed of Hyaluronic Acid Exhibits High Gene Expression in the Lungs

Gene therapy is a breakthrough treatment strategy against several intractable and lethal diseases that previously lacked established treatments. Viral and nonviral vectors have been studied to realize higher gene transfection efficiencies and to suppress the degradation of gene by nucleolytic enzymes in vivo. However, it is often the case that the addition of a vector results in adverse effects. In this study, we identified formulations of dry naked plasmid DNA (pDNA) powders with no vector showing significantly higher gene expression than pDNA solutions including vectors such as polyethylenimine (PEI) in the lungs of mice. We prepared the naked pDNA powders by spray-freeze-drying with various excipients. The gene expression of naked pDNA powders exceeded those of pDNA solutions containing PEI, naked pDNA solution, and reconstituted pDNA powder. Gene expression of each naked pDNA powder was dependent on the composition of excipients. Among them, the mice that were administered the pDNA powder composed of low-molecular-weight hyaluronic acid (LHA) as an excipient showed the highest gene expression. The lactate dehydrogenase activity and concentration of inflammatory cytokines in bronchoalveolar lavage fluid were comparable to those caused by ultrapure water. The results suggest that useful dry naked nucleic acid powders for inhalation could be created by optimizing the excipients, offering new insights into the development of pulmonary gene therapy.

Anti-inflammatory activity of Sanghuangporus sanghuang by suppressing the TLR4-mediated PI3K/AKT/mTOR/IKKβ signaling pathway

Sanghuangporus sanghuang (SS) is a mushroom that belongs to the genus Sanghuangporus and it is commonly called “Sangwhang” in Taiwan.

Doxorubicin-Induced Systemic Inflammation Is Driven by Upregulation of Toll-Like Receptor TLR4 and Endotoxin Leakage

Doxorubicin is one of the most effective chemotherapeutic agents used for cancer treatment, but it causes systemic inflammation and serious multiorgan side effects in many patients. In this study, we report that upregulation of the proinflammatory Toll-like receptor TLR4 in macrophages by doxorubicin is an important step in generating its toxic side effects. In patient serum, doxorubicin treatment resulted in leakage of endotoxin and inflammatory cytokines into circulation. In mice, doxorubicin damaged the intestinal epithelium, which also resulted in leakage of endotoxin from the gut flora into circulation. Concurrently, doxorubicin increased TLR4 expression in macrophages both in vitro and in vivo, which further enhanced the sensitivity of these cells to endotoxin. Either depletion of gut microorganisms or blockage of TLR4 signaling effectively decreased doxorubicin-induced toxicity. Taken together, our findings suggest that doxorubicin-triggered leakage of endotoxin into the circulation, in tandem with enhanced TLR4 signaling, is a candidate mechanism underlying doxorubicin-induced systemic inflammation. Our study provides new insights for devising relevant strategies to minimize the adverse effects of chemotherapeutic agents such as doxorubicin, which may extend its clinical uses to eradicate cancer cells. Cancer Res; 76(22); 6631-42. ©2016 AACR.

Effect of Toll-Like Receptor 4 on Synovial Injury of Temporomandibular Joint in Rats Caused by Occlusal Interference

Synovitis is an important disease that causes intractable pain in TMJ. Some investigations suggested that the increasing expression of IL-1β secreted by synovial lining cells plays an important role in synovial inflammation and cartilage destruction in TMJ. In our previous research, the results demonstrated that TLR4 is involved in the expression of IL-1β in SFs from TMJ with lipopolysaccharide stimulation. However, the inflammatory response that occurred in synovial membrane is not caused by bacterial infection. In the current study, we investigated whether or not TLR4 participates in the inflammatory responses and the expression of IL-1β in synovial membrane of rats induced by occlusal interference. The results showed that obvious inflammation changes were observed in the synovial membranes and the expression of TLR4 and IL-1β was increased at both mRNA and protein levels in the occlusal interference rats. In addition, the inflammation reactions and the increased expression of IL-1β could be restrained by treatment with TAK-242, a blocker of TLR4 signaling. The results prompted us that the activation of TLR4 may be involved in the inflammatory reactions and increased expression of IL-1β in patients with synovitis and participate in the mechanisms of the initiation and development of synovial injury by regulating the expression of inflammatory mediators like IL-1β in synovial membranes.

Innate-like function of memory Th17 cells for enhancing endotoxin-induced acute lung inflammation through IL-22

Lipopolysaccharide (LPS)-induced acute lung injury (ALI) is known as a mouse model of acute respiratory distress syndrome; however, the function of T-cell-derived cytokines in ALI has not yet been established. We found that LPS challenge in one lung resulted in a rapid induction of innate-type pro-inflammatory cytokines such as IL-6 and TNF-α, followed by the expression of T-cell-type cytokines, including IL-17, IL-22 and IFN-γ. We discovered that IL-23 is important for ALI, since blockage of IL-23 by gene disruption or anti-IL-12/23p40 antibody treatment reduced neutrophil infiltration and inflammatory cytokine secretion into the bronchoalveolar lavage fluid (BALF). IL-23 was mostly produced from F4/80(+)CD11c(+) alveolar macrophages, and IL-23 expression was markedly reduced by the pre-treatment of mice with antibiotics, suggesting that the development of IL-23-producing macrophages required commensal bacteria. Unexpectedly, among T-cell-derived cytokines, IL-22 rather than IL-17 or IFN-γ played a major role in LPS-induced ALI. IL-22 protein levels were higher than IL-17 in the BALF after LPS instillation, and the major source of IL-22 was memory Th17 cells. Lung memory CD4(+) T cells had a potential to produce IL-22 at higher levels than IL-17 in response to IL-1β plus IL-23 without TCR stimulation. Our study revealed an innate-like function of the lung memory Th17 cells that produce IL-22 in response to IL-23 and are involved in exaggeration of ALI.

Association of the TLR4 signaling pathway in the retina of streptozotocin-induced diabetic rats

BACKGROUND

Diabetic retinopathy is severe damage to the retina caused by complications of diabetes, and is the prevailing cause of blindness. Accumulating evidence from both animal models and humans suggests that the inflammatory process plays a key role in the development of diabetic retinopathy and is facilitated by innate immune response. The aim of this study was to examine whether the TLR4 signaling pathway was involved in the streptozotocin-induced diabetic rat retina.

METHODS

Diabetes was induced by a single intraperitoneal injection of streptozotocin, and rat diabetic retinopathy was examined at 4 weeks of diabetes duration. Then the accumulated leukocytes were counted in vivo by acridine orange leukocyte fluorography, and the retinal vascular permeability was measured by the Evans blue assay. The expressions of TLR4 and its downstream signaling molecules were measured by RT-PCR or Western blot respectively. To evaluate the effect of blocking TLR4 on diabetic retinopathy, TAK-242, a selective TLR4 antagonist, was administered by intraperitoneal injection.

RESULTS

Our results showed that the retina of diabetic rats demonstrated accumulated leukocytes and retinal vascular permeability. The mRNA and protein expressions of TLR4 were upregulated in streptozotocin-treated diabetic rat retina. Furthermore, the protein levels of TLR4 downstream signaling molecules were significantly increased in streptozotocin-treated animals. In addition, the protein levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and interferon (IFN)-β, three downstream proinflammatory cytokines of TLR4 signal transduction pathway, were also markedly increased in diabetic rats. Administration of TAK-242 attenuated leukocytes accumulated and retinal vascular permeability, and decreased TLR4 downstream signaling molecules and proinflammatory cytokines in streptozotocin-induced animals.

CONCLUSIONS

Together, these data have demonstrated that TLR4 has a critical role in streptozotocin-induced diabetic retinopathy at the level of inflammatory cytokine induction, in both the MyD88-dependent and MyD88-independent pathways. TLR4 may become a new potential pharmacological target for treating diabetic retinopathy.

Inhibitor of nuclear factor-κB, SN50, attenuates lipopolysaccharide-induced lung injury in an isolated and perfused rat lung model

NF-κB cell permeable inhibitory peptide (SN50) inhibits translocation of nuclear factor-κB (NF-κB) and production of inflammatory cytokines that are implicated in lipopolysaccharide (LPS)-induced lung injury (LPSLI). However, the protective effect of SN50 in LPSLI is unclear. We explored the cellular and molecular mechanisms of SN50 treatment in LPSLI. LPSLI was induced by intratracheal instillation of 10 mg/kg LPS using an isolated and perfused rat lung model. SN50 was administered in the perfusate 15 minutes before LPS was administered. Hemodynamics, lung histologic change, inflammatory responses, and activation of apoptotic pathways were evaluated. After LPSLI, increased pulmonary vascular permeability and lung weight gain was observed. The levels of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, myeloperoxidase, and macrophage inflammatory protein-2 increased in bronchoalveolar lavage fluids. Lung-tissue expression of TNF-α, IL-1β, mitogen-activated protein kinases (MAPKs), caspase-3, p-AKT (serine-threonine kinase, also known as protein kinase B), and plasminogen activator inhibitor-1 (PAI-1) was greater in the LPS group compared with controls. Upregulation and activation of NF-κB was associated with increased lung injury in LPSLI. SN50 attenuated the inflammatory responses, including expression of IL-1β, TNF-α, myeloperoxidase, MAPKs, PAI-1, and NF-κB; downregulation of apoptosis indicated by caspase-3 and p-AKT expression was also observed. In addition, SN50 mitigated the increase in the lung weight, pulmonary vascular permeability, and lung injury. In conclusion, LPSLI is associated with inflammatory responses, apoptosis, and coagulation. NF-κB is an important therapeutic target in the treatment of LPSLI. SN50 inhibits translocation of NF-κB and attenuates LPSLI.

Hypoxia preconditioning increases survival and decreases expression of Toll-like receptor 4 in pulmonary artery endothelial cells exposed to lipopolysaccharide

Abstract Pulmonary or systemic infections and hypoxemic respiratory failure are among the leading causes of admission to intensive care units, and these conditions frequently exist in sequence or in tandem. Inflammatory responses to infections are reproduced by lipopolysaccharide (LPS) engaging Toll-like receptor 4 (TLR4). Apoptosis is a hallmark of lung injury in sepsis. This study was conducted to determine whether preexposure to LPS or hypoxia modulated the survival of pulmonary artery endothelial cells (PAECs). We also investigated the role TLR4 receptor expression plays in apoptosis due to these conditions. Bovine PAECs were cultured in hypoxic or normoxic environments and treated with LPS. TLR4 antagonist TAK-242 was used to probe the role played by TLR4 receptors in cell survival. Cell apoptosis and survival were measured by caspase 3 activity and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) incorporation. TLR4 expression and tumor necrosis factor α (TNF-α) production were also determined. LPS increased caspase 3 activity in a TAK-242-sensitive manner and decreased MTT incorporation. Apoptosis was decreased in PAECs preconditioned with hypoxia prior to LPS exposure. LPS increased TNF-α production, and hypoxic preconditioning blunted it. Hypoxic preconditioning reduced LPS-induced TLR4 messenger RNA and TLR4 protein. TAK-242 decreased to baseline the LPS-stimulated expression of TLR4 messenger RNA regardless of environmental conditions. In contrast, LPS followed by hypoxia substantially increased apoptosis and cell death. In conclusion, protection from LPS-stimulated PAEC apoptosis by hypoxic preconditioning is attributable in part to reduction in TLR4 expression. If these signaling pathways apply to septic patients, they may account for differing sensitivities of individuals to acute lung injury depending on oxygen tensions in PAECs in vivo.

Toll-like receptor 4 antagonist attenuates intracerebral hemorrhage-induced brain injury

BACKGROUND AND PURPOSE

Accumulating evidence indicates that inflammatory responses cause secondary injury after intracerebral hemorrhage (ICH). We recently demonstrated the involvement of toll-like receptor 4 (TLR4) signaling in these processes. The purpose of the current study was to investigate the protective effect and mechanism of TAK-242 (Ethyl (6R)-6-[N-(2-chloro-4-fluorophenyl) sulfamoyl] cyclohex-1-ene-1 -carboxylate, Takeda), a TLR4 antagonist, in an ICH mouse model.

METHODS

TAK-242 was intraperitoneally injected 6 hours after ICH once daily for 5 successive days. We assessed neurological deficit scores; changes in brain water content; and levels of inflammatory factors, DNA damage, and neuronal degeneration in perihematomal region 1, 3, and 5 days after ICH. Peripheral inflammatory cell infiltration was determined using flow cytometry; and the expression of TLR4 downstream signaling molecules was assessed by Western blot.

RESULTS

TAK-242 significantly reduced brain water content, neurological deficit scores, and levels of inflammatory factors. The levels of DNA damage and neuronal degeneration were also significantly decreased, as was peripheral inflammatory cell infiltration. The expression of TLR4 downstream signaling molecules, including myeloid differentiation primary response gene 88, toll/IR-1(TIR)-domain-containing adaptor protein inducing interferon-beta IκBα, nuclear factor-κBp65, and phosphorylated nuclear factor-κBp65, was significantly downregulated.

CONCLUSIONS

The results suggest that TLR4 antagonist reduced inflammatory injury and neurological deficits in a mouse model of ICH. The mechanism may involve decreased expression of signaling molecules downstream of TLR4.

Adiponectin prevents islet ischemia-reperfusion injury through the COX2-TNFα-NF-κB-dependent signal transduction pathway in mice

Islets are exceptionally susceptible to ischemia-reperfusion injury, an increased incidence of primary graft nonfunctionality, and β-cell death during a transplant procedure. Therefore, islets require protection during the early stages of the transplant procedure. Based on the beneficial vascular and anti-inflammatory activity of adiponectin, we hypothesize that adiponectin protects islet cells against ischemia-reperfusion injury and graft dysfunction after transplantation. To examine the effects of adiponectin on the resistance of islet ischemia-reperfusion injury, we used the islet hypoxia-reoxygenation injury model and performed kidney subcapsular syngeneic islet transplants to assess the islets' vitality and function. Furthermore, we utilized lipopolysaccharide (LPS)-induced or tumor necrosis factor α (TNFα)-induced damage to islet cells to model the inflammation of post-transplant ischemia-reperfusion injury and transplanted islets in adiponectin knockout mice to explore whether the protective action of adiponectin is involved in TNFα production and nuclear transcription factor-κB (NF-κB) activation. Adiponectin suppressed TNFα production and IκB-α phosphorylation; decreased hypoxia-reoxygenation and LPS-induced and TNFα-induced islet apoptosis; and improved islet function in vivo and in vitro. Our results demonstrate that adiponectin protects the islet from injury. We show that islet protection occurs in response to ischemia-reperfusion and is dependent on the suppression of islet production by TNFα through cyclooxygenase 2 and the inhibition of the TNFα-induced NF-κB activation pathways.

A TLR4-interacting SPA4 peptide inhibits LPS-induced lung inflammation

The interaction between surfactant protein-A (SP-A) and TLR4 is important for host defense. We have recently identified an SPA4 peptide region from the interface of SP-A-TLR4 complex. Here, we studied the involvement of the SPA4 peptide region in SP-A-TLR4 interaction using a two-hybrid system, and biological effects of SPA4 peptide in cell systems and a mouse model. HEK293 cells were transfected with plasmid DNAs encoding SP-A or a SP-A-mutant lacking SPA4 peptide region and TLR4. Luciferase activity was measured as the end-point of SP-A-TLR4 interaction. NF-κB activity was also assessed simultaneously. Next, the dendritic cells or mice were challenged with Escherichia coli-derived LPS and treated with SPA4 peptide. Endotoxic shock-like symptoms and inflammatory parameters (TNF-α, NF-κB, leukocyte influx) were assessed. Our results reveal that the SPA4 peptide region contributes to the SP-A-TLR4 interaction and inhibits the LPS-induced NF-κB activity and TNF-α. We also observed that the SPA4 peptide inhibits LPS-induced expression of TNF-α, nuclear localization of NF-κB-p65 and cell influx, and alleviates the endotoxic shock-like symptoms in a mouse model. Our results suggest that the anti-inflammatory activity of the SPA4 peptide through its binding to TLR4 can be of therapeutic benefit.

Regulatory role of antigen-induced interleukin-10, produced by CD4(+) T cells, in airway neutrophilia in a murine model for asthma

It has been suggested that interleukin (IL)-10 exerts immunosuppressive effects on allergic inflammation, including asthma, mainly through inhibition of Th2 cell-mediated eosinophilic airway inflammation. In a model of experimental asthma utilizing multiple intratracheal antigen challenges in sensitized mice, IL-10 production as well as eosinophilia and neutrophilia in the lung were induced by the multiple challenges. In this study, we set out to reveal the cellular source of endogenously produced IL-10, and the roles of IL-10 in airway leukocyte inflammation using an anti-IL-10 receptor monoclonal antibody. Balb/c mice were sensitized i.p. with ovalbumin+Al(OH)(3), and then challenged by intratracheal administration of ovalbumin 4 times. Flow cytometric analyses revealed that the cellular source of IL-10 was CD4(+) T cells lacking the transcription factor, forkhead box P3. Treatment with anti-IL-10 receptor monoclonal antibody prior to the 4th challenge significantly augmented airway neutrophilia as well as the production of IL-1β, and CXC chemokines, keratinocyte-derived chemokine (KC) and macrophage inflammatory protein (MIP)-2, but not airway eosinophilia, Th2 cytokine (IL-4 and IL-5) production, or a late-phase increase in specific airway resistance. Approximately 40% of IL-10 receptor(+) cells expressed the macrophage marker F4/80, whereas only 3-4% of the IL-10 receptor(+) cells were granulocyte differentiation antigen (Gr)-1(high) cells (neutrophils). In conclusion, multiple airway antigen challenges induced the proliferation of IL-10-expressing CD4(+) T cells in regulating airway neutrophilia. Systemic blockade of IL-10 function coincided with increases in IL-1β and CXC chemokines. Thus, IL-1β and CXC chemokines may be targets for development of novel pharmacotherapy for neutrophilic asthma.

Nilotinib ameliorates lipopolysaccharide-induced acute lung injury in rats

The present study aimed to investigate the effect of the new tyrosine kinase inhibitor, nilotinib on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats and explore its possible mechanisms. Male Sprague-Dawley rats were given nilotinib (10mg/kg) by oral gavage twice daily for 1week prior to exposure to aerosolized LPS. At 24h after LPS exposure, bronchoalveolar lavage fluid (BALF) samples and lung tissue were collected. The lung wet/dry weight (W/D) ratio, protein level and the number of inflammatory cells in the BALF were determined. Optical microscopy was performed to examine the pathological changes in lungs. Malondialdehyde (MDA) content, superoxidase dismutase (SOD) and reduced glutathione (GSH) activities as well as nitrite/nitrate (NO(2)(-)/NO(3)(-)) levels were measured in lung tissues. The expression of inflammatory cytokines, tumor necrosis factor-α (TNF-α), transforming growth factor-β(1) (TGF-β(1)) and inducible nitric oxide synthase (iNOS) were determined in lung tissues. Treatment with nilotinib prior to LPS exposure significantly attenuated the LPS-induced pulmonary edema, as it significantly decreased lung W/D ratio, protein concentration and the accumulation of the inflammatory cells in the BALF. This was supported by the histopathological examination which revealed marked attenuation of LPS-induced ALI in nilotinib treated rats. In addition, nilotinib significantly increased SOD and GSH activities with significant decrease in MDA content in the lung. Nilotinib also reduced LPS mediated overproduction of pulmonary NO(2)(-)/NO(3)(-) levels. Importantly, nilotinib caused down-regulation of the inflammatory cytokines TNF-α, TGF-β(1) and iNOS levels in the lung. Taken together, these results demonstrate the protective effects of nilotinib against the LPS-induced ALI. This effect can be attributed to nilotinib ability to counteract the inflammatory cells infiltration and hence ROS generation and regulate cytokine effects.

Pathogenesis of indirect (secondary) acute lung injury

At present, therapeutic interventions to treat acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) remain largely limited to lung-protective strategies, as no real molecular-pathophysiologic-driven therapeutic intervention has yet become available. This is in part the result of the heterogeneous nature of the etiological processes that contribute to the state of ALI/ARDS. This article sets out to understand the development of ALI resulting from indirect pulmonary insults, such as extrapulmonary sepsis and trauma, shock, burn injury or mass transfusion, as opposed to direct pulmonary challenges, such as pneumonia, aspiration or lung contusion. Here, we consider not only the experimental and clinical data concerning the roles of various immune (neutrophil, macrophage, lymphocyte and dendritic) as well as nonimmune (epithelial and endothelial) cells in orchestrating the development of ALI resulting from indirect pulmonary stimuli, but also how these cell populations might be targeted therapeutically.