Lipoxin A4 attenuation of endothelial inflammation response mimicking pancreatitis-induced lung injury

Eicosanoid signaling in neuroinflammation associated with Alzheimer's disease

Alzheimer's disease (AD) is a prevalent neurodegenerative condition affecting a substantial portion of the global population. It is marked by a complex interplay of factors, including the accumulation of amyloid plaques and tau tangles within the brain, leading to neuroinflammation and neuronal damage. Recent studies have underscored the role of free lipids and their derivatives in the initiation and progression of AD. Eicosanoids, metabolites of polyunsaturated fatty acids like arachidonic acid (AA), emerge as key players in this scenario. Remarkably, eicosanoids can either promote or inhibit the development of AD, and this multifaceted role is determined by how eicosanoid signaling influences the immune responses within the brain. However, the precise molecular mechanisms dictating the dual role of eicosanoids in AD remain elusive. In this comprehensive review, we explore the intricate involvement of eicosanoids in neuronal function and dysfunction. Furthermore, we assess the therapeutic potential of targeting eicosanoid signaling pathways as a viable strategy for mitigating or halting the progression of AD.

Mechanisms of 15-Epi-LXA4-Mediated HO-1 in Cytoprotection Following Inflammatory Injury

INTRODUCTION

Heme oxygenase-1 (HO-1) is a protective protein in oxidative stress response. LXA4 is an "inflammatory braking signal" that is widely studied at present. The purpose of this study was to elucidate that LXA4 can protect cells by inducing HO-1 in human pulmonary microvascular endothelial cells (HPMECs) as in vitro model to explain acute lung injury after severe acute pancreatitis.

METHODS

This study was performed in two parts: (1) To investigate the mechanisms of lipoxin A4-induced HO-1 expression in vitro, the study subjects were divided into four groups: a control group, LXA4 group (50 ng/mL LXA4), inhibitor group (50 ng/mL LXA4 + 20 μM LY294002 or 50 ng/mL LXA4 + 2 nmol/mL Bis II), and agonist group (50 ng/mL insulin-like growth factor 1, PMA). Western blotting was used to detect the expression of p-Akt, Akt, protein kinase C (PKC), p-Nrf2, Nrf2, and Keap1, and the location of Nrf2 was detected using immunofluorescence. The activation of antioxidant responsive element induced by Nrf2 was detected using Electrophoretic Mobility Shift Assay and (2) to investigate the cytoprotection of HO-1 induced by LXA4 in vitro, the subjects were divided into four groups: a control group, tumor necrosis factor α (TNF-α) group (50 ng/mL), LXA4 group (50 ng/mL TNF-α + 50 ng/mL LXA4), and Zinc protoporphyrin IX group (pretreated with 0.5 μM Zinc protoporphyrin IXfor 12 h, followed by 50 ng/mL TNF-α + 50 ng/mL LXA4). BCECF/AM-labeled THP-1 cells were used to analyze the adhesion of HPMECs, and a mitochondrial membrane potential assay kit with JC-1 was used to analyze the apoptosis of HPMECs.

RESULTS

In part one, (1) LXA4 upregulated the expression of HO-1 in a dose-dependent manner and (2) LXA4 activated the PI3K/Akt and PKC pathways and modulated the phosphorylation and subsequent depolymerization of Nrf2 from Keap1, promoting the translocation of Nrf2 to the nucleus. In part two, (1) LXA4 reversed the changes in mitochondrial membrane potential to alleviate apoptosis in HPMECs and (2) LXA4 attenuated the adhesion of HPMECs induced by TNF-α.

CONCLUSIONS

LXA4 can activate the PI3K/Akt and PKC pathways and induce the phosphorylation of Nrf2, resulting in the upregulation of HO-1. In addition, LXA4 alleviates adhesion and protects mitochondrial function by upregulating the expression of HO-1, which exerts cytoprotection in severe acute pancreatitis-induced lung injury.

Simvastatin Upregulates Lipoxin A4 and Accelerates Neuroinflammation Resolution After Intracerebral Hemorrhage

BACKGROUND

Previous studies have demonstrated that statins can relieve inflammatory brain injury after intracerebral hemorrhage (ICH), but the mechanisms remain poorly characterized. This study aims to test whether simvastatin exerts an anti-inflammatory effect by regulating the proresolving mediators.

METHODS

First, male Sprague-Dawley rats had an injection of 200 μL autologous blood. Then, rats were randomly divided into groups treated with simvastatin (i.p. 2 mg/kg) or vehicle. Next, all rats underwent pro-resolving mediator lipoxin A4 (LXA4) level detection, flow cytometric, immunofluorescence, brain edema measurement, neurological scoring and western blot analysis.

RESULTS

We found that simvastatin significantly increased the plasma level of LXA4, an endogenous formyl-peptide receptor 2 (FPR2) agonist, in the early stage of ICH. Consistent with the effect of simvastatin, exogenous LXA4 administration also promoted apoptosis of the circulating neutrophils, reduced neutrophils brain infiltration, and ameliorated inflammatory brain injury after ICH. In addition, similar to simvastatin, exogenous LXA4 markedly decreased the level of phosphorylated p38 mitogen-activated protein kinase (MAPK) and the apoptosis-related proteins myeloid cell leukemia 1(Mcl-1)/Bax ratio (a decreased ratio represents the induction of apoptosis) in circulating neutrophils isolated from ICH rats. Notably, all of the aforementioned effects of simvastatin on ICH were significantly abolished by Boc-2, a selective antagonist of FPR2. Moreover, simvastatin led to a similar Mcl-1/Bax ratio reduction as SB203580 (a p38 MAPK inhibitor), but it was abolished by P79350 (a p38 MAPK agonist).

CONCLUSION

Collectively, these results suggest that simvastatin ameliorates ICH-mediated inflammatory brain injury, possibly by upregulating the level of pro-resolving mediator LXA4 and further stimulating the FPR2/p38 MAPK signaling pathway.

Identification of ceRNA regulatory network in acute pancreatitis and acute recurrent pancreatitis

OBJECTIVE

The aim of this study was to find differentially expressed long noncoding RNAs (lncRNAs), microRNAs (miRNAs) and mRNAs and related signaling pathways, contributing to understanding the molecular mechanism of acute recurrent pancreatitis (ARP).

METHODS

First, peripheral whole blood samples from five acute pancreatitis (AP) patients, five ARP patients and five healthy individuals ( N ) were collected for RNA sequencing. Second, differentially/specifically expressed lncRNAs, miRNAs and mRNAs were identified in AP vs. N , ARP vs. N and ARP. Third, the ceRNA (lncRNA-miRNA-mRNA) networks of common/specifical lncRNAs, miRNAs and mRNAs were constructed in AP vs. N , ARP vs. N and ARP. Finally, functional analysis of common mRNAs in AP vs. N and ARP vs. N was performed.

RESULTS

A total of 315 common lncRNAs, 12 common miRNAs and 909 common mRNAs were identified between AP and ARP. Ninety-four specifically expressed lncRNAs, one specifically expressed miRNAs and 286 specifically expressed mRNAs were found in ARP. Some interaction pairs were identified in AP and ARP, such as LUCAT1/NEAT1-hsa-miR-16-2-3p-HK2, CHRM3-AS2-hsa-miR-122-5p/hsa-miR-145-3p-DBH/CACNA1C, CHRM3-AS2-hsa-miR-200a-3p-PDGFD, RBM26-AS1-hsa-miR-200b-3p-FHIT and LINC00891/KTN1-AS1-hsa-miR-143-3p-tyrosine kinase (TXK). ASAP1-IT2/DGCR9-hsa-miR-342-5p-ABCC5/MAP2K6 was the only one specific interaction pair identified in ARP. Four significantly enriched signaling pathways were identified in AP vs. N and ARP vs. N , including amino sugar and nucleotide sugar metabolism (involved NPL and HK2), MAPK signaling pathway (involved CACNA1C and PDGFD), metabolic pathways (involved DBH and FHIT) and leukocyte transendothelial migration (involved TXK).

CONCLUSION

The identified altered lncRNAs, miRNAs, mRNAs and related signaling pathways may be involved in the AP development and recurrence.

Signal Pathways and Markers Involved in Acute Lung Injury Induced by Acute Pancreatitis

Acute pancreatitis (AP) is a common acute abdominal disease with a mortality rate of about 30%. Acute lung injury (ALI) is a common systemic complication of acute pancreatitis, with progressive hypoxemia and respiratory distress as the main manifestations, which can develop into acute respiratory distress syndrome or even multiple organ dysfunction syndrome (MODS) in severe cases, endangering human health. In the model of AP, pathophysiological process of the lung can be summarized as oxidative stress injury, inflammatory factor infiltration, and alveolar cell apoptosis. However, the intrinsic mechanisms underlying AP and how it leads to ALI are not fully understood. In this paper, we summarize recent articles related to AP leading to ALI, including the signal transduction pathways and biomarkers of AP-ALI. There are factors or pathway aggravating ALI, the JAK2-STAT3 signaling pathway, NLRP3/NF-κB pathway, mitogen-activated protein kinase, PKC pathway, neutrophil protease (NP)-LAMC2-neutrophil pathway, and the P2X7 pathway, and there are important transcription factors in the NRF2 signal transduction pathway which could give researchers better understanding of the underlying mechanisms controlling AP and ALI and lay the foundation for finally curing ALI induced by AP.

Metabolomics reveals the reproductive abnormality in female zebrafish exposed to environmentally relevant levels of climbazole

Climbazole (CBZ) ubiquitously detected in the aquatic environment may disrupt fish reproductive function. Thus far, the previous study has focused on its transcriptional impact of steroidogenesis-related genes on zebrafish, but the underlying toxic mechanism still needs further investigation at the metabolic level. In this study, adult zebrafish were chronically exposed to CBZ at concentrations of 0.1 (corresponding to the real concentration in surface water), 10, and 1000 μg/L and evaluated for reproductive function by egg production, with subsequent ovarian tissue samples taken for histology, metabolomics, and other biochemical analysis. After 28 days' exposure, fecundity was significantly decreased in all exposure groups, with the inhibition of oocytes in varying developmental stages to a certain degree. The decrease in retinoic acid and sex hormones, down-regulated genes important in steroidogenesis, and increase in oxidized/reduced glutathione ratio and occurrence of apoptotic cells were observed in zebrafish ovaries following exposure to CBZ even at environmentally realistic concentrations, suggesting that alternations in steroidogenesis and oxidative stress can play significant roles in CBZ-triggered reproductive toxicity. Besides, mass spectrometry imaging analysis validated the results from metabolomics analysis. Our findings provide novel perspectives for unveiling the mechanism of reproductive dysfunction by CBZ and highlight its risk to fish reproduction.

Resolution-Based Therapies: The Potential of Lipoxins to Treat Human Diseases

Inflammation is an a physiological response instead an essential response of the organism to injury and its adequate resolution is essential to restore homeostasis. However, defective resolution can be the precursor of severe forms of chronic inflammation and fibrosis. Nowadays, it is known that an excessive inflammatory response underlies the most prevalent human pathologies worldwide. Therefore, great biomedical research efforts have been driven toward discovering new strategies to promote the resolution of inflammation with fewer side-effects and more specificity than the available anti-inflammatory treatments. In this line, the use of endogenous specialized pro-resolving mediators (SPMs) has gained a prominent interest. Among the different SPMs described, lipoxins stand out as one of the most studied and their deficiency has been widely associated with a wide range of pathologies. In this review, we examined the current knowledge on the therapeutic potential of lipoxins to treat diseases characterized by a severe inflammatory background affecting main physiological systems, paying special attention to the signaling pathways involved. Altogether, we provide an updated overview of the evidence suggesting that increasing endogenously generated lipoxins may emerge as a new therapeutic approach to prevent and treat many of the most prevalent diseases underpinned by an increased inflammatory response.

Lipoxin A4-Mediated p38 MAPK Signaling Pathway Protects Mice Against Collagen-Induced Arthritis

The aim of the article was to study the mechanism of Lipoxin A4 (LXA4)-mediated p38 MAPK pathway protecting mice against collagen-induced arthritis (CIA). The impact of LXA4 (0, 5, 10, 15 nM) on synoviocytes proliferation of CIA mice was detected using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. CIA mice were treated with LXA4, SB203580 (a p38 inhibitor), and/or anisomycin (a p38 agonist), and the arthritis severity score in each mouse was determined. The gene or protein expressions were detected with Western Blotting, ELISA, or qRT-PCR. LXA4 inhibited the synoviocytes proliferation of CIA mice with decreased levels of TNF-α, IL-6, IL-1β, and IFN-γ and reduced p-p38/total p38 expression in synoviocytes in a dose-dependent manner. LXA4 levels were decreased in synovial tissues and plasma of CIA mice, but p-p38/total p38 expression was increased in synovial tissues. LXA4 could downregulate p-p38/total p38 expression in synovial tissues of CIA mice. Both LXA4 and SB203580 reduced arthritis severity score of CIA mice with the reduction of synovial tissue hyperplasia and inflammatory cell infiltration. CIA mice treated with LXA4 and SB203580 had lower levels of TNF-α, IL-6, IL-1β, and IFN-γ, accompanying decreased MDA as well as increased SOD, CAT,and GPx. However, anisomycin could reverse the protect effects of LXA4 on CIA mice regarding the abovementioned inflammatory factors and oxidative stress indexes. LXA4 protected mice against collagen-induced arthritis via inhibiting p38 MAPK signaling pathway, which may be a potential new therapeutic target for rheumatoid arthritis.

Ferulic acid alleviates lipopolysaccharide-induced acute lung injury through inhibiting TLR4/NF-κB signaling pathway

Ferulic acid (FA) exhibits anti-inflammatory, antidiabetic, antihyperlipidemic, antioxidant, neuroprotective, and antihypertensive effects. This study aimed to determine whether FA could ameliorate lipopolysaccharide (LPS)-induced inflammatory responses and acute lung injury (ALI) in mice. Mice were challenged with LPS intratracheally to induce ALI 1 h after 3 days of FA (25, 50, and 100 mg/kg) or dexamethasone (DEX; 5 mg/kg) administration. The lung tissues and bronchoalveolar lavage fluid (BALF) were collected 12 h after the LPS challenge. Pretreatment with FA or DEX could attenuate lung histopathological change, complement deposition, and lung wet-to-dry weight ratio of mice injured by LPS. Meanwhile, the influx of neutrophils and macrophages, as well as the production of proinflammatory cytokine (tumor necrosis factor-alpha, interleukin 1 beta [IL-1β], and IL-6), in BALF of ALI mice was significantly decreased. Moreover, FA or DEX markedly reversed the LPS-induced elevation of myeloperoxidase activity and monocyte chemoattractant protein-1 level in lung tissues of ALI mice. In addition, the Western blot analysis demonstrated that FA or DEX effectively inhibited the LPS-induced activation of the toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signaling pathway in lung tissues. The current study suggested that the alleviating effect of FA against LPS-induced ALI might be partially due to the inhibition of the inflammatory response via inactivation of the TLR4/NF-κB signaling pathway.

Mediterranean Diet: Lipids, Inflammation, and Malaria Infection

The Mediterranean diet (MedDiet) consists of consumption of vegetables and healthy oils and have beneficial effects on metabolic and inflammatory diseases. Our goal here is to discuss the role of fatty acid content in MedDiet, mostly omega-3, omega-6, and omega-9 on malaria. Malaria affects millions of people around the globe. The parasite Plasmodium causes the disease. The metabolic and inflammatory alterations in the severe forms have damaging consequences to the host. The lipid content in the MedDiet holds anti-inflammatory and pro-resolutive features in the host and have detrimental effects on the Plasmodium. The lipids from the diet impact the balance of pro- and anti-inflammation, thus, lipids intake from the diet is critical to parasite elimination and host tissue damage caused by an immune response. Herein, we go into the cellular and molecular mechanisms and targets of the MedDiet fatty acids in the host and the parasite, reviewing potential benefits of the MedDiet, on inflammation, malaria infection progression, and clinical outcome.

Lipoxin A4 Ameliorates Acute Pancreatitis-Associated Acute Lung Injury through the Antioxidative and Anti-Inflammatory Effects of the Nrf2 Pathway

Acute lung injury (ALI) is a critical event involved in the pathophysiological process of acute pancreatitis (AP). Many methods have been widely used for the treatment of AP-ALI, but few are useful during early inflammation. Lipoxin A4 (LXA4), a potent available anti-inflammatory and novel antioxidant mediator, has been extensively studied in AP-ALI, but its underlying mechanism as a protective mediator is not clear. This research was conducted to identify the possible targets and mechanisms involved in the anti-AP-ALI effect of LXA4. First, we confirmed that LXA4 strongly inhibited AP-ALI in mice. Next, using ELISA, PCR, and fluorescence detection to evaluate different parameters, LXA4 was shown to reduce the inflammatory cytokine production induced by AP and block reactive oxygen species (ROS) generation in vivo and in vitro. In addition, TNF-α treatment activated the nuclear factor E2-related factor 2 (Nrf2) signaling pathway and its downstream gene heme oxygenase-1 (HO-1) in human pulmonary microvascular endothelial cells (HPMECs), and LXA4 further promoted their expression. This study also provided evidence that LXA4 phosphorylates Ser40 and triggers its nuclear translocation to activate Nrf2. Moreover, when Nrf2-knockout (Nrf2^−/−) mice and cells were used to further assess the effect of the Nrf2/HO-1 pathway, we found that Nrf2 expression knockdown partially eliminated the effect of LXA4 on the reductions in inflammatory factor levels while abrogating the inhibitory effect of LXA4 on the ROS generation stimulated by AP-ALI. Overall, LXA4 attenuated the resolution of AP-induced inflammation and ROS generation to mitigate ALI, perhaps by modulating the Nrf2/HO-1 pathway. These findings have laid a foundation for the treatment of AP-ALI.

Downregulation of TNF-α/TNF-R1 Signals by AT-Lipoxin A4 May Be a Significant Mechanism of Attenuation in SAP-Associated Lung Injury

Our previous studies verified the potent anti-inflammatory effects against severe acute pancreatitis (SAP) of AT-Lipoxin A4 and their analogues. However, the anti-inflammatory effects of AT-Lipoxin A4 on SAP-associated lung injury are not thoroughly known. We used western blot, polymerase chain reaction (PCR), and immunofluorescence to investigate the downregulation of TNF-α signals in cellular and animal models of SAP-associated lung injury following AT-Lipoxin A4 intervention. In vitro, we found that AT-Lipoxin A4 markedly suppressed protein expression in TNF-α signals in human pulmonary microvascular endothelial cell, such as tumor necrosis factor receptor-associated factor 2 (TRAF2), TNF-R1-associated death domain (TRADD), receptor-interacting protein (RIP), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin. Moreover, AT-Lipoxin A4 inhibited downstream signals activated by TNF-α, including NF-κB/p65, JNK/MAPK, and ERK/MAPK. In vivo, AT-Lipoxin A4 significantly decreased pathological scores of the pancreas and lungs and the serum levels of IL-6 and TNF-α. Immunofluorescence, western blotting, and real-time PCR assay showed that AT-Lipoxin A4 significantly attenuated the expression of TNF-R1, TRADD, TRAF2, and RIP in the lungs of SAP rats. In addition, the activation of NF-κB was also downregulated by AT-Lipoxin A4 administration as compared with SAP rats. AT-Lipoxin A4 could inhibit the production of proinflammatory mediators and activation of TNF-α downstream signals such as NF-κB and MAPK. Downregulation of TNF-α signals by AT-Lipoxin A4 may be a significant mechanism in the attenuation of SAP-associated lung injury.

Dynamic changes and clinical significance of LXA4 in the perioperative period of cardiopulmonary bypass

Dynamic changes in lipoxin A₄ (LXA₄) in child patients with congenital heart disease (CHD), in the perioperative period of cardiopulmonary bypass (CPB) were studied. Peripheral blood was collected from 16 child patients (CPB group) before operation (Tc), after operation (T0), at 1 day after operation (T1), at 3 days after operation (T3), and at 7 days after operation (T7); and from 17 children with no CHD (control group). The level of LXA₄ in peripheral blood was detected via enzyme-linked immunosorbent assay (ELISA). Clinical data of the child patients were collected. The white blood cell (WBC) count, the proportion of neutrophils (N%) and high-sensitivity C-reactive protein (hs-CRP) levels were also detected, followed by statistical analysis. The plasma LXA₄ levels in CPB group at Tc were significantly lower compared to that in the control group (P<0.01). In CPB group, the level of LXA₄ showed an increasing trend at T0, WBC and hs-CRP were transiently increased at T0 and increased most significantly at T1. N% was obviously increased at T0 compared to that at Tc and was still significantly higher at T7 compared to that at Tc. The CPB time and aortic clamping time were positively correlated with the time in the Pediatric Intensive Care Unit (PICU), the application time of ventilator, and the hs-CRP level at T0. The LXA₄ level at each time-point had no correlation with other indexes. In conclusion, the inflammatory response after CPB increases the synthesis of LXA₄ with an anti-inflammatory effect, but LXA₄ cannot be used as a sensitive index for monitoring inflammation.

Lipoxin A4 receptor agonist BML-111 induces autophagy in alveolar macrophages and protects from acute lung injury by activating MAPK signaling

Background

Acute lung injury (ALI) is a life-threatening lung disease where alveolar macrophages (AMs) play a central role both in the early phase to initiate inflammatory responses and in the late phase to promote tissue repair. In this study, we examined whether BML-111, a lipoxin A4 receptor agonist, could alter the phenotypes of AM and thus present prophylactic benefits for ALI.

Methods

In vitro, isolated AMs were treated with lipopolysaccharide (LPS) to induce ALI. In response to BML-111 pre-treatment, apoptosis and autophagy of AMs were examined by flow cytometry, and by measuring biomarkers for each process. The potential involvement of MAPK1 and mTOR signaling pathway was analyzed. In vivo, an LPS-induced septic ALI model was established in rats and the preventative significance of BML-111 was assessed. On the cellular and molecular levels, the pro-inflammatory cytokines TNF-α and IL-6 from bronchoalveolar lavage were measured by ELISA, and the autophagy in AMs examined using Western blot.

Results

BML-111 inhibited apoptosis and induced autophagy of AMs in response to ALI inducer, LPS. The enhancement of autophagy was mediated through the suppression of MAPK1 and MAPK8 signaling, but independent of mTOR signaling. In vivo, BML-111 pre-treatment significantly alleviated LPS-induced ALI, which was associated with the reduction of apoptosis, the dampened production of pro-inflammatory cytokines in the lung tissue, as well as the increase of autophagy of AMs.

Conclusions

This study reveals the prophylactic significance of BML-111 in ALI and the underlying mechanism: by targeting the MAPK signaling but not mTOR pathway, BML-111 stimulates autophagy in AMs, attenuates the LPS-induced cell apoptosis, and promotes the resolution of ALI.

LipoxinA4 attenuates acute pancreatitis-associated acute lung injury by regulating AQP-5 and MMP-9 expression, anti-apoptosis and PKC/SSeCKS-mediated F-actin activation

An essential component of acute pancreatitis(AP)-induced acute lung injury(ALI) is the inflammation that is part of the body's systemic inflammatory response to a variety of systemic stimuli. Lipoxins(LXs) are considered important endogenous lipids that mediate the resolution of inflammation. In previous studies, we found that Lipoxin A4 (LXA4) reduced AP-induced pulmonary oedema and TNF-α production in lung. However, the underlying mechanism remains unclear. Due to the above studies, we investigated the aquaporin, matrix metalloprotein, apoptosis and PKC/SSeCKS signal pathway in cellular and animal models of AP-associated lung injury following LXA4 intervention. In this study, we first proved LXA4 could effectively promote F-actin reconstruction and regulate its expression in pulmonary microvascular endothelial cells both in vivo and vitro via suppressing PKC/SSeCKS signalling pathway. Next, we found that LXA4 attenuated cell growth inhibition and apoptosis in lung tissues of AP-ALI mice and HPMECs. Additionally, we demonstrated that LXA4 could regulate the expression of AQP-5 and MMP-9 to stabilize the permeability of pulmonary microvascular endothelial cell. In summary, our results suggest that the anti-inflammatory eff ;ects of LXA4 may be due to the inhibition of both the PKC/SSeCKS pathway and apoptosis to reduce alveolar fluid exudation and to the regulation of AQP-5 and MMP-9 expression to maintain the clearance of alveolar fluid. Thus, LXA4 is capable of exerting protective eff ;ects on AP-induced ALI.

[Effect of lipoxin A4 on the expression of Toll-like receptor 4 and TNF receptor-associated factor 6 in the liver of obese rats with sepsis]

OBJECTIVE

To study the protective effect of lipoxin A4 (LXA4) against sepsis induced by lipopolysaccharide (LPS) in rats with obesity and its effect on the expression of Toll-like receptor 4 (TLR4) and TNF receptor-associated factor 6 (TRAF6) in the liver.

METHODS

A total of 60 male Sprague-Dawley rats aged three weeks were randomly divided into a normal group and an obesity group, with 30 rats in each group. A rat model of obesity was established by high-fat diet. Each of the two groups was further randomly divided into control group, sepsis group, and LXA4 group, and 8 rats were selected from each group. The rats in the control, sepsis, and LXA4 groups were treated with intraperitoneal injection of normal saline, LPS, and LXA4+LPS respectively. Twelve hours later, blood samples were collected from the heart and liver tissue samples were also collected. ELISA was used to measure the serum levels of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Western blot was used to measure the protein expression of TLR4 and TRAF6 in liver tissue. Quantitative real-time PCR was used to measure the mRNA expression of TLR4 and TRAF6.

RESULTS

After being fed with high-fat diet for 6 weeks, the obesity group had significantly higher average weight and Lee's index than the normal group (P<0.05). Compared with the normal group, the obesity group had significant increases in the serum levels of IL-6 and TNF-α (P<0.05). In the normal group or the obesity group, the sepsis subgroup had significant increases in the serum levels of IL-6 and TNF-α compared with the control subgroup (P<0.05), while the LXA4 subgroup had significant reductions in the two indices compared with the sepsis subgroup (P<0.05). Compared with the normal group, the obesity group had significant increases in the protein and mRNA expression of TLR4 and TRAF6 (P<0.05). In the normal group or the obesity group, the sepsis subgroup had significant increases in the protein and mRNA expression of TLR4 and TRAF6 compared with the control subgroup (P<0.05). Compared with the sepsis subgroup, the LXA4 subgroup had significant reductions in the protein and mRNA expression of TLR4 and TRAF6 (P<0.05).

CONCLUSIONS

LXA4 can reduce the serum levels of IL-6 and TNF-α and alleviate inflammatory response. LXA4 can inhibit the expression of TLR4 and TRAF6 in the liver of septic rats, possibly by inhibiting the TLR4 signaling pathway.

Macrophage migration inhibitory factor antagonist (S,R)3‑(4‑hydroxyphenyl)‑4,5‑dihydro‑5‑isoxazole acetic acid methyl ester attenuates inflammation and lung injury in rats with acute pancreatitis in pregnancy

Macrophage migration inhibitory factor (MIF) is an inflammatory cytokine involved in many acute and chronic inflammatory diseases. However, its role in acute lung injury associated with acute pancreatitis in pregnancy (APIP) has not yet been elucidated. The present study was undertaken to clarify the effect and potential mechanism of MIF antagonist (S,R)3‑(4‑hydroxyphenyl)‑4,5‑dihydro‑5‑isoxazole acetic acid methyl ester (ISO‑1) in the development of acute lung injury in rats with APIP. Eighteen late‑gestation SD rats were randomly assigned to three groups: Sham operation (SO) group, APIP group, and ISO‑1 group. All the rats were sacrificed 6 h after modeling. The severity of pancreatitis was evaluated by serum amylase (AMY), lipase (LIPA), tumor necrosis factor (TNF)‑α, interleukin (IL)‑1β and IL‑6 and assessing the histopathological score. Lung injury was determined by performing histology and inflammatory cell infiltration investigations. Western blot analysis was used to detect the protein expression of MIF, phosphorylated and total P38 and nuclear factor‑κB (NF‑κB) protein in lungs. The results showed that MIF was upregulated in the lung of APIP rats. Compared with APIP group, the intervention of ISO‑1 alleviated the pathological injury of the pancreas and lungs, decreased serum AMY and LIPA, attenuated serum concentrations of TNF‑α, IL‑1β, and IL‑6, reduced the number of MPO‑positive cells in the lung and inhibited the activation of P38MAPK and NF‑κB. These results suggest that MIF is activated in lung injury induced by APIP. Furhtermore, the present findings indicate that the MIF antagonist ISO‑1 has a protective effect on lung injury and inflammation, which may be associated with deactivating the P38MAPK and NF‑κB signaling pathway.

Anti-inflammatory effect of stem bark of Paulownia tomentosa Steud. in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and LPS-induced murine model of acute lung injury

ETHNOPHARMACOLOGICAL RELEVANCE

The leaves, bark, and flowers of Paulownia tomentosa Steud. have been widely used as a traditional medicine in East Asia to treat inflammatory and infectious diseases.

AIM OF THE STUDY

We investigated the protective effect of the methanol stem bark extract of P. tomentosa using an animal model of lipopolysaccharide (LPS)-induced acute lung injury (ALI).

MATERIALS AND METHODS

The UPLC Q-TOF-MS profiles for the methanol extract of P. tomentosa stem bark showed that verbascoside and isoverbascoside were the predominant compounds. Raw 264.7 cells were used for inhibitory effects of cytokine production in vitro. C57BL/6N mice were administered intranasally with LPS (10μg/per mouse) to induce ALI. H&E staining was used to evaluate histological changes in the lung.

RESULTS

Treatment with P. tomentosa stem bark extract (PTBE) suppressed the production of IL-6 and TNF-α in LPS-stimulated RAW 264.7 macrophages, and the recruitment of neutrophils and macrophages in the BALF of mice with LPS-induced ALI. PTBE also decreased the levels of reactive oxygen species (ROS) and pro-inflammatory cytokines in the BALF. PTBE reduced the levels of nitric oxide (NO) in the serum and of inducible nitric oxide synthase (iNOS) in the lung of ALI mice. PTBE also attenuated the infiltration of inflammatory cells and the expression of monocyte chemoattractant protein-1 (MCP-1) in the lung. In addition, PTBE suppressed the activation of NF-κB and the reduced expression of superoxide dismutase 3 (SOD3) in the lung.

CONCLUSION

The results suggest that PTBE has a protective effect on LPS-induced ALI.

Paeoniflorin ameliorates acute necrotizing pancreatitis and pancreatitis‑induced acute renal injury

Acute renal injury caused by acute necrotizing pancreatitis (ANP) is a common complication that is associated with a high rate of mortality. Paeoniflorin is the active ingredient of paeonia radix and exhibits a number of pharmacological effects, such as anti-inflammatory, anticancer, analgesic and immunomodulatory effects. The present study detected the potential treatment effects of paeoniflorin on acute renal injury induced by ANP in a rat model. The optimal dose of paeoniflorin for preventing acute renal injury induced by ANP was determined. Then, the possible protective mechanism of paeoniflorin was investigated. The serum levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 were measured with enzyme-linked immunosorbent assay kits. Renal inflammation and apoptosis were measured by immunohistochemistry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay. The expression of nitric oxide in kidney tissues was also evaluated. The p38 mitogen-activated protein kinases (MAPKs) were measured by western blotting. The results shown that paeoniflorin may ameliorate acute renal injury following ANP in rats by inhibiting inflammatory responses and renal cell apoptosis. These effects may be associated with the p38MAPK and nuclear factor-κB signal pathway.

Lipoxin A4 Reduces Inflammation Through Formyl Peptide Receptor 2/p38 MAPK Signaling Pathway in Subarachnoid Hemorrhage Rats

BACKGROUND AND PURPOSE

Lipoxin A4 (LXA4) has been reported to reduce inflammation in several neurological injury models. We studied the effects of LXA4 on neuroinflammation after subarachnoid hemorrhage (SAH) in a rat model.

METHODS

Two hundred and thirty-eight Sprague-Dawley male rats, weight 280-320 g, were used. Exogenous LXA4 (0.3 and 1.0 nmol) were injected intracerebroventricularly at 1.5 hours after SAH. Neurological scores, brain water content, and blood-brain barrier were evaluated at 24 hours after SAH; Morris water maze and T-maze tests were examined at 21 days after SAH. The expression of endogenous LXA4 and its receptor formyl peptide receptor 2 (FPR2), as well as p38, interleukin-1β, and interleukin-6 were studied either by ELISA or by Western blots. Neutrophil infiltration was observed by myeloperoxidase staining. FPR2 siRNA was used to knock down LXA4 receptor.

RESULTS

The expression of endogenous LXA4 decreased, and the expression of FPR2 increased after SAH. Exogenous LXA4 decreased brain water content, reduced Evans blue extravasation, and improved neurological functions and improved the learning and memory ability after SAH. LXA4 reduced neutrophil infiltration and phosphorylation of p38, interleukin-1β, and interleukin-6. These effects of LXA4 were abolished by FPR2 siRNA.

CONCLUSIONS

Exogenous LXA4 inhibited inflammation by activating FPR2 and inhibiting p38 after SAH. LXA4 may serve as an alternative treatment to relieve early brain injury after SAH.

The association between red blood cell distribution width and acute pancreatitis associated lung injury in patients with acute pancreatitis

BACKGROUND

Red blood cell distribution width (RDW) that describes red blood cell volume heterogeneity is a common laboratory test. Our aim was to focus on the association between RDW and acute pancreatitis associated lung injury (APALI).

METHODOLOGY

A total of 152 acute pancreatitis (AP) patients who conformed to the criteria were included in this study. The demographic data, medical histories and laboratory measures was obtained from each patient on admission, further, the medical histories and biological data were analyzed, retrospectively.

RESULTS

Increased RDW at admission was observed in patients with APALI compared with the non-APALI groups. Our results exhibited that RDW was an independent risk factor for APALI after adjusting leukocyte, neutrophil percentage, random blood glucose (RBG), total bilirubin (TB) and total bile acid (TBA) (Crude model) (OR=2.671;CI 95% 1.145-6.230; P=0.023), further adjustment based on Crude model for sex and age did not attenuate the significantly high risk of APALI in patients with AP, RWD still remained a roles as an independent risk factor for APALI (OR=2.653;CI95 % 1.123-6.138; P=0.026).

CONCLUSIONS

Our study demonstrate that RDW at admission is associated with APALI and should be considered as an underlying risk factor of APALI.

Lipoxin A4 attenuates endothelial dysfunction during experimental cerebral malaria

A breakdown of the brain-blood barrier (BBB) due to endothelial dysfunction is a primary feature of cerebral malaria (CM). Lipoxins (LX) are specialized pro-resolving mediators that attenuate endothelial dysfunction in different vascular beds. It has already been shown that LXA4 prolonged Plasmodium berghei-infected mice survival by a mechanism that depends on inhibiting IL-12 production and CD8(+)IFN-γ(+) T cells in brain tissue; however, the effects of this treatment on endothelial dysfunction induced during experimental cerebral malaria (ECM) remains to be elucidated. Herein, we investigate the role of LXA4 on endothelial dysfunction during ECM. The treatment of P. berghei-infected mice with LXA4 prevented BBB breakdown and ameliorated behavioral symptoms but did not modulate TNF-α production. In addition, microcirculation analysis showed that treatment with LXA4 significantly increased functional capillary density in brains of P. berghei-infected C57BL/6 mice. Furthermore, histological analyses of brain sections demonstrated that exogenous LXA4 reduced capillary congestion that was accompanied by reduced ICAM-1 expression in the brain tissue. In agreement, LXA4 treatment of endothelial cells stimulated by Plasmodium berghei (Pb)- or Plasmodium falciparum (Pf)-parasitized red blood cells (RBCs) inhibited ICAM-1 expression. Additionally, LXA4 treatment restored the expression of HO-1 that is reduced during ECM. As well, LXA4 treatment inhibits PbRBC and PfRBC adhesion to endothelial cells that was reversed by the use of an HO-1 inhibitor (ZnPPIX). Our results demonstrate for the first time that LXA4 ameliorates endothelial dysfunction during ECM by modulating ICAM-1 and HO-1 expression in brain tissue.

Emodin ameliorates LPS-induced acute lung injury, involving the inactivation of NF-κB in mice

Acute lung injury (ALI) and its severe manifestation of acute respiratory distress syndrome (ARDS) are well-known illnesses. Uncontrolled and self-amplified pulmonary inflammation lies at the center of the pathology of this disease. Emodin, the bio-active coxund of herb Radix rhizoma Rhei, shows potent anti-inflammatory properties through inactivation of nuclear factor-κB (NF-κB). The aim of this study was to evaluate the effect of emodin on lipopolysaccharide (LPS)-induced ALI in mice, and its potential bio-mechanism. In our study, BALB/c mice were stimulated with LPS to induce ALI. After 72 h of LPS stimulation, pulmonary pathological changes, lung injury scores, pulmonary edema, myeloperoxidase (MPO) activity, total cells, neutrophils, macrophages, TNF-α, IL-6 and IL-1β in bronchoalveolar lavage fluid (BALF), and MCP-1 and E-selectin expression were notably attenuated by emodin in mice. Meanwhile, our data also revealed that emodin significantly inhibited the LPS-enhanced the phosphorylation of NF-κB p65 and NF-κB p65 DNA binding activity in lung. Our data indicates that emodin potently inhibits LPS-induced pulmonary inflammation, pulmonary edema and MCP-1 and E-selectin expression, and that these effects were very likely mediated by inactivation of NF-κB in mice. These results suggest a therapeutic potential of emodin as an anti-inflammatory agent for ALI/ARDS treatment.