Nitric oxide stimulates macrophage inflammatory protein-2 expression in sepsis

Immunomodulatory efficacy of Cousinia thomsonii C.B. Clarke in ameliorating inflammatory cascade expressions

ETHNOPHARMACOLOGICAL RELEVANCE

Cousinia thomsonii is traditionally known for treating various diseases including joint pain, swelling, body ache, asthma, dermatitis, cough and arthritis.

AIM OF THE STUDY

This study employs lipopolysaccharide induced inflammatory wistar-rat model to evaluate efficacy of Cousinia thomsonii active-extracts on the expression of crucial inflammatory markers viz. iNOS, PPAR-γ, Rel-A, COX-2 and serum analysis of CRP.

MATERIALS AND METHODS

Methanol and aqueous extracts were administered orally at 25, 50, 100 mg/kg doses for 21 days. Serum was collected on 22nd day and rats were sacrificed to extract paw tissues. Dexamethasone (0.5 mg/kg) served as positive control. Immunoblotting and qPCR was used for expression analysis of iNOS, PPAR-γ, Rel-A, COX-2 respectively. ELISA was employed for evaluating CRP levels. Discovery-studio and Auto-Dock-Vina were used to check docking interactions of various identified compounds.

RESULTS

Both extracts caused dose-dependent decline in iNOS, Rel-A, COX-2 and CRP levels, while there was a dose-dependent increase in PPAR-γ expression. Methanol extract dominated immunomodulatory potential as compared with the aqueous extract. The results of the GCMS revealed the presence of ten compounds. Some of these compounds include 1-Octacosanol, Ethyl Linoleate, 1-Heptacosanol, 1-Hexadecanol, 1-Dodecanol and Behenic alcohol having strong anti-inflammatory, antimicrobial, anti-acne and anti-viral activities. Molecular Docking scores were calculated between each target protein and selected compounds. The best affinity/interactions were observed between 1-Octacosanol towards iNOS, PPAR-γ, Rel-A, COX-2 and CRP with binding energy of -10.4, -11.1, -8.6, -9.9 and -7.9 (kcal/mol) respectively. These compounds may act as strong inhibitors for iNOS, Rel-A, COX-2 and CRP or as agonists for PPAR-γ; thereby inducing anti-inflammatory/immuno-modulatory activities.

CONCLUSIONS

The results indicate that Cousinia thomsonii contains therapeutically active compounds and thus could serve as potential therapeutic regimen against diverse inflammatory diseases.

miR-369-3p modulates inducible nitric oxide synthase and is involved in regulation of chronic inflammatory response

Dendritic cells are the most important antigen-presenting cells that link the innate and acquired immune system. In our previous study, we identified that the upregulation of miR-369-3p suppresses the LPS-induced inflammatory response, reducing C/EBP-β, TNFα and IL-6 production. With the aim of gaining further insight into the biological function of miR-369-3p during acute inflammatory response, in the present study we identified novel gene targets of miR-369-3p and demonstrated the suppressive ability of these genes on the inflammatory dendritic cells. Bioinformatic analyses revealed that iNOS is a potential target of miR-369-3p. We demonstrated that the ectopic induction of miR-369-3p markedly reduced iNOS mRNA and protein as well as NO production. Moreover, we found that the upregulation of miR-369-3p decreased the release of TNFα, IL-6, IL-12, IL-1α, IL-1β in response to LPS, and increased the production of anti-inflammatory cytokines such as IL-10 and IL-1RA. In addition, LPS-induced nuclear translocation of NF-kB was inhibited by miR-369-3p. Levels of miR-369-3p were decreased in human inflamed regions of human intestine obtained from IBD patients. Our results provide novel additional information on miR-369-3p as a potential core of the signaling regulating the inflammatory response. These findings suggest that miR-369-3p should be considered as a potential target for the future development of new molecular therapeutic approaches.

Preparation of newly identified polysaccharide from Pleurotus eryngii and its anti-inflammation activities potential

The anti-inflammatory effects of two newly identified Pleurotus eryngii polysaccharides (WPEP, NPEP) were determined in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages in this study. Characterization analysis revealed that molecular weights of WPEP and NPEP were 167 and 274 kDa, and were mainly composed of glucose with β-type glycosidic linkages. WPEP and NPEP could significantly inhibit LPS-induced inflammatory responses by regulating the production of NO, Protaglandin E2 (PGE₂ ), Interleukin-1β (IL-1β), Tumor necrosis factor-α (TNF-α), and Interleukin-6 (IL-6). This was through the blocking of the activation of Mitogen-activated protein kinase (MAPK) pathway by inhibiting phosphorylation of p38, extracellular regulation of protein kinases 1/2, and stress-activated protein kinase/jun aminoterminal kinase. Moreover, WPEP and NPEP inhibited NF-κB signaling by reducing nuclear translocation and phosphorylation of p65. Overall, our results, for the first time identified two P. eryngii polysaccharides and demonstrated the related anti-inflammatory effects, which indicated the favorable potential of P. eryngii polysaccharide as specific functional foods. PRACTICAL APPLICATION: This study prepared and characterized newly identified Pleurotus eryngii water-soluble polysaccharide fractions and elucidated the nutritional benefits, mainly the immune response related to anti-inflammatory activities by utilizing lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Collectively, results of this study suggested that the P. eryngii polysaccharide fractions could be considered as potential candidates for exploration in the development of new immunomodulatory agent or functional supplementary foods.

Nitric oxide synthase 2 enhances the survival of mice during Salmonella Typhimurium infection-induced sepsis by increasing reactive oxygen species, inflammatory cytokines and recruitment of neutrophils to the peritoneal cavity

Sepsis, a leading cause of death in intensive care units, is primarily caused due to an exaggerated immune response. The hyperactive inflammatory response mediated by immune cells against infectious organisms and their toxins results in host cell death and tissue damage, the hallmarks of septic shock. Therefore, molecules that modulate inflammatory responses are attractive therapeutic targets for sepsis. Nitric oxide (NO) is a signaling molecule, which is implicated in regulating diverse immune functions. Although, the protective roles of NO in infectious diseases are well documented, its importance in sepsis is controversial. In the present study, the effects of intra-peritoneal injection of mice with Salmonella Typhimurium, a Gram-negative intracellular pathogen, were studied which leads to a rapid upregulation of serum cytokines and infiltration of neutrophils to the peritoneal cavity. Surprisingly, the induction of inflammatory cytokines and chemokines, e.g. IL6 and CCL2, and the infiltration of neutrophils into the peritoneal cavity are mitigated in mice lacking Nitric oxide synthase 2 (NOS2). The reduced inflammatory response in Nos2^-/- mice is accompanied by greater bacterial burden in the peritoneal cavity, lower thymic atrophy, higher liver damage and cardiovascular dysfunction followed by decreased survival. However, no significant differences are observed in other responses between C57BL/6 wild type (WT) and Nos2^-/- mice: induction of glucocorticoids, phagocytic ability and apoptosis of peritoneal cells. This study clearly highlights the NOS2-dependent and -independent responses in this mouse model of peritonitis induced sepsis. Importantly, pre-treatment of Nos2^-/- mice with DETA-NO, a NO donor, upon infection, restores neutrophil recruitment, reduces bacterial numbers in the peritoneal cavity, improves liver and cardio-vascular function and enhances survival. Interestingly, DETA-NO treatment does not significantly increase the survival of infected WT mice. The implications of these results and the complex roles of NO as a target molecule during sepsis are discussed.

iNOS as a Driver of Inflammation and Apoptosis in Mouse Skeletal Muscle after Burn Injury: Possible Involvement of Sirt1 S-Nitrosylation-Mediated Acetylation of p65 NF-κB and p53

Inflammation and apoptosis develop in skeletal muscle after major trauma, including burn injury, and play a pivotal role in insulin resistance and muscle wasting. We and others have shown that inducible nitric oxide synthase (iNOS), a major mediator of inflammation, plays an important role in stress (e.g., burn)-induced insulin resistance. However, it remains to be determined how iNOS induces insulin resistance. Moreover, the interrelation between inflammatory response and apoptosis is poorly understood, although they often develop simultaneously. Nuclear factor (NF)-κB and p53 are key regulators of inflammation and apoptosis, respectively. Sirt1 inhibits p65 NF-κB and p53 by deacetylating these transcription factors. Recently, we have shown that iNOS induces S-nitrosylation of Sirt1, which inactivates Sirt1 and thereby increases acetylation and activity of p65 NF-κB and p53 in various cell types, including skeletal muscle cells. Here, we show that iNOS enhances burn-induced inflammatory response and apoptotic change in mouse skeletal muscle along with S-nitrosylation of Sirt1. Burn injury induced robust expression of iNOS in skeletal muscle and gene disruption of iNOS significantly inhibited burn-induced increases in inflammatory gene expression and apoptotic change. In parallel, burn increased Sirt1 S-nitrosylation and acetylation and DNA-binding capacity of p65 NF-κB and p53, all of which were reversed or ameliorated by iNOS deficiency. These results indicate that iNOS functions not only as a downstream effector but also as an upstream enhancer of burn-induced inflammatory response, at least in part, by Sirt1 S-nitrosylation-dependent activation (acetylation) of p65 NF-κB. Our data suggest that Sirt1 S-nitrosylation may play a role in iNOS-mediated enhanced inflammatory response and apoptotic change, which, in turn, contribute to muscle wasting and supposedly to insulin resistance after burn injury.

Agrimonolide from Agrimonia pilosa suppresses inflammatory responses through down-regulation of COX-2/iNOS and inactivation of NF-κB in lipopolysaccharide-stimulated macrophages

BACKGROUND

Agrimonolide from Agrimonia pilosa showed a strong anti-inflammatory activity, and the present study aims to reveal potential mechanisms on molecular level explaining its anti-inflammatory effect.

HYPOTHESIS/PURPOSE

To investigate the mechanism of anti-inflammatory activity of agrimonolide.

STUDY DESIGN

Anti-inflammatory activity of agrimonolide in cells was applied.

METHODS

Anti-inflammatory activity of agrimonolide isolated from Agrimonia pilosa was evaluated using lipopolysaccharide (LPS) stimulated RAW 264.7 cell models. The productions of IL-1β, IL-6, TNF-α and NO were determined by ELISA and nitrite analysis, respectively. The expressions of iNOS and COX-2 were measured by western blotting and RT-PCR analysis.

RESULTS

The pre-treatment with agrimonolide significantly reduced the levels of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α), as well as attenuated the expression of iNOS and COX-2 in LPS-stimulated macrophages. Furthermore, agrimonolide inhibited the activation of JNK and p38 MAPKs and decreased the activation of JAK-STAT and NF-κB in LPS-stimulated macrophages.

CONCLUSION

The present study suggested that agrimonolide exerted anti- inflammatory activity, at least in part, via suppressing LPS-induced activation of JAK-STATs and p38 MAPKs signaling pathway.

Inflammatory stimuli induce inhibitory S-nitrosylation of the deacetylase SIRT1 to increase acetylation and activation of p53 and p65

Inflammation increases the abundance of inducible nitric oxide synthase (iNOS), leading to enhanced production of nitric oxide (NO), which can modify proteins by S-nitrosylation. Enhanced NO production increases the activities of the transcription factors p53 and nuclear factor κB (NF-κB) in several models of disease-associated inflammation. S-nitrosylation inhibits the activity of the protein deacetylase SIRT1. SIRT1 limits apoptosis and inflammation by deacetylating p53 and p65 (also known as RelA), a subunit of NF-κB. We showed in multiple cultured mammalian cell lines that NO donors or inflammatory stimuli induced S-nitrosylation of SIRT1 within CXXC motifs, which inhibited SIRT1 by disrupting its ability to bind zinc. Inhibition of SIRT1 reduced deacetylation and promoted activation of p53 and p65, leading to apoptosis and increased expression of proinflammatory genes. In rodent models of systemic inflammation, Parkinson's disease, or aging-related muscular atrophy, S-nitrosylation of SIRT1 correlated with increased acetylation of p53 and p65 and activation of p53 and NF-κB target genes, suggesting that S-nitrosylation of SIRT1 may represent a proinflammatory switch common to many diseases and aging.

In vivo anti-inflammatory activity of Tabernaemontana divaricata leaf extract on male albino mice

AIM

To study the in vivo anti-inflammatory activity of Tabernaemontana divaricata leaf extract on male albino mice.

METHODS

Aqueous decoction and methanol leaf extracts were tested for their ability to reduce croton oil-induced edema in the mouse ear after topical application. The methanol leaf extract dose-dependently inhibited the croton oil-induced ear edema in mice (ID50 <500 μg·cm(-2)). A bioassay-guided liquid-liquid fractionation of this methanol extract gave four active fractions: water insoluble (F1), hexane (F2), ethyl acetate (F3) and water (F4).

RESULTS

The hexane fraction showed a very high activity (42.1% inhibition at 0.7 μg·cm(-2)) as compared to the control. The other fractions were less active (F1: 56.1% at 506.2 μg·cm(-2); F3: 57.3% at 289.3 μg·cm(-2); and F4: 31.9% for 203.8 μg·cm(-2)) while indomethacin gave 48.8% of inhibition at 90 μg·cm(-2). The activity of F1 and F3 may be at least in part explained by the presence of anti-inflammatory flavonoids, while the activity was not correlated to the tannin contents. No compounds were detected in the most active F2 fraction.

CONCLUSIONS

The results give a rational support to the traditional use of T. divaricata in tropical India as anti-inflammatory agent.

Hesperidin inhibits inflammatory response induced by Aeromonas hydrophila infection and alters CD4+/CD8+ T cell ratio

Background. Aeromonas hydrophila is an opportunistic bacterial pathogen that is associated with a number of human diseases. Hesperidin (HES) has been reported to exert antioxidant and anti-inflammatory activities. Objectives. The aim of this study was to investigate the potential effect of HES treatment on inflammatory response induced by A. hydrophila infection in murine. Methods. A. hydrophila-infected mice were treated with HES at 250 mg/kg b.wt./week for 4 consecutive weeks. Phagocytosis, reactive oxygen species production, CD4⁺/CD8⁺ T cell ratio, and CD14 expression on intestinal infiltrating monocytes were evaluated. The expression of E-selectin and intercellular adhesion molecule 1 on stimulated HUVECs and RAW macrophage was evaluated. Results. Percentage of CD4⁺ T cells in the intestinal tissues of infected treated mice was highly significantly increased; however, phagocytic index, ROS production, CD8⁺ T cells percentage, and CD14 expression on monocytes were significantly reduced. On the other hand, HES significantly inhibited A-LPS- and A-ECP-induced E-selectin and ICAM-1 expression on HUVECs and ICAM-1 expression on RAW macrophage. Conclusion. Present data indicated that HES has a potential role in the suppression of inflammatory response induced by A. hydrophila toxins through downmodulation of ROS production and CD14 and adhesion molecules expression, as well as increase of CD4⁺/CD8⁺ cell ratio.

Role of endogenous IL-18 in the lung during endotoxin-induced systemic inflammation

Background

Overactivated neutrophils are causes of acute lung injury, which is a major clinical problem with significant morbidity and mortality in sepsis. Serum interleukin (IL)-18 levels correspond to severity of systemic inflammation.

Aim

To elucidate the roles of endogenous IL-18 in lung injury during endotoxin-induced systemic inflammation.

Methods

Wild-type (WT) and IL-18 gene knockout (KO) mice were injected with lipopolysaccharide (40 mg/kg) intraperitoneally and killed. Lungs were collected at 0 and 12 h to assess mRNA for intercellular adhesion molecule (ICAM)-1, inducible nitric oxide synthase, myeloperoxidase, immunohistochemistry (cleaved caspase-3, 8-hydroxy-2-deoxyguanosine), and wet/dry ratio. Blood was collected at 0, 1, 12, 18, and 24 h to assess plasma cytokine levels.

Results

The survival rates at 24 h were approximately 43% and 76% in the WT and KO mice, respectively. Plasma IL-18 levels were induced time-dependently only in the WT mice. Plasma interferon-γ levels were significantly higher in the WT than in the KO mice at 12 h, but IL-6 and tumor necrosis factor-α levels did not differ between the WT and KO mice. At 12 h, the WT mice showed higher myeloperoxidase activity (P < 0.05), ICAM-1, and wet/dry ratios than KO mice. Cleaved caspase-3 positive neutrophils, which migrated in the lung interstitium, were lower in WT mice than in KO mice.

Conclusions

Endogenous IL-18 induced neutrophil accumulation, accompanied by induction of ICAM-1 expression, inhibition of neutrophil apoptosis, and increased inducible nitric oxide synthase-induced oxidative tissue injury in the lung, leading to lung edema and poor outcome during endotoxemia.

ERK2-dependent activation of c-Jun is required for nontypeable Haemophilus influenzae-induced CXCL2 upregulation in inner ear fibrocytes

The inner ear, composed of the cochlea and the vestibule, is a specialized sensory organ for hearing and balance. Although the inner ear has been known as an immune-privileged organ, there is emerging evidence indicating an active immune reaction of the inner ear. Inner ear inflammation can be induced by the entry of proinflammatory molecules derived from middle ear infection. Because middle ear infection is highly prevalent in children, middle ear infection-induced inner ear inflammation can impact the normal development of language and motor coordination. Previously, we have demonstrated that the inner ear fibrocytes (spiral ligament fibrocytes) are able to recognize nontypeable Haemophilus influenzae, a major pathogen of middle ear infection, and upregulate a monocyte-attracting chemokine through TLR2-dependent NF-κB activation. In this study, we aimed to determine the molecular mechanism involved in nontypeable H. influenzae-induced cochlear infiltration of polymorphonuclear cells. The rat spiral ligament fibrocytes were found to release CXCL2 in response to nontypeable H. influenzae via activation of c-Jun, leading to the recruitment of polymorphonuclear cells to the cochlea. We also demonstrate that MEK1/ERK2 signaling pathway is required for nontypeable H. influenzae-induced CXCL2 upregulation in the rat spiral ligament fibrocytes. Two AP-1 motifs in the 5'-flanking region of CXCL2 appeared to function as a nontypeable H. influenzae-responsive element, and the proximal AP-1 motif was found to have a higher binding affinity to nontypeable H. influenzae-activated c-Jun than that of the distal one. Our results will enable us better to understand the molecular pathogenesis of middle ear infection-induced inner ear inflammation.

Ethyl pyruvate protects rats from phosgene-induced pulmonary edema by inhibiting cyclooxygenase2 and inducible nitric oxide synthase expression

Phosgene is a poorly water-soluble gas penetrating the lower respiratory tract which can induce acute lung injury characterized by a latent phase of fatal pulmonary edema. Pulmonary edema caused by phosgene is believed to be a consequence of oxidative stress and inflammatory responses. Ethyl pyruvate (EP) has been demonstrated to have anti-inflammatory and anti-oxidative properties in vivo and in vitro. The potential therapeutic role of EP in phosgene-induced pulmonary edema has not been addressed so far. In the present study, we aim to investigate the protective effects of EP on phosgene-induced pulmonary edema and the underlying mechanisms. Rats were administered with EP (40 mg kg(-1)) and RAW264.7 cells were also incubated with it (0, 2, 5 or 10 µm) immediately after phosgene (400 ppm, 1 min) or air exposure. Wet-to-dry lung weight ratio (W:D ratio), nitric oxide (NO) and prostaglandin E(2) (PGE(2)) production, cyclooxygenase2 (COX-2) and inducible nitric oxide synthase (iNOS) expression, and mitogen-activated protein kinases activities (MAPKs) were measured. Our results showed that EP treatment attenuated phosgene-induced pulmonary edema and decreased the level of NO and PGE(2) dose-dependently. Furthermore, EP significantly reduced COX-2 expression, iNOS expression and MAPK activation induced by phosgene. Moreover, specific inhibitors of MAPKs reduced COX-2 and iNOS expression induced by phosgene. These findings suggested that EP has a protective role against phosgene-induced pulmonary edema, which is mediated in part by inhibiting MAPK activation and subsequently down-regulating COX-2 and iNOS expression as well as decreasing the production of NO and PGE(2).

Involvement of adenosine A2A receptors in engulfment-dependent apoptotic cell suppression of inflammation

Efficient execution of apoptotic cell death followed by efficient clearance mediated by professional macrophages is a key mechanism in maintaining tissue homeostasis. Removal of apoptotic cells usually involves three central elements: 1) attraction of phagocytes via soluble "find me" signals, 2) recognition and phagocytosis via cell surface-presenting "eat me" signals, and 3) suppression or initiation of inflammatory responses depending on additional innate immune stimuli. Suppression of inflammation involves both direct inhibition of proinflammatory cytokine production and release of anti-inflammatory factors, which all contribute to the resolution of inflammation. In the current study, using wild-type and adenosine A(2A) receptor (A2AR) null mice, we investigated whether A2ARs, known to mediate anti-inflammatory signals in macrophages, participate in the apoptotic cell-mediated immunosuppression. We found that macrophages engulfing apoptotic cells release adenosine in sufficient amount to trigger A2ARs, and simultaneously increase the expression of A2ARs, as a result of possible activation of liver X receptor and peroxisome proliferators activated receptor δ. In macrophages engulfing apoptotic cells, stimulation of A2ARs suppresses the NO-dependent formation of neutrophil migration factors, such as macrophage inflammatory protein-2, using the adenylate cyclase/protein kinase A pathway. As a result, loss of A2ARs results in elevated chemoattractant secretion. This was evident as pronounced neutrophil migration upon exposure of macrophages to apoptotic cells in an in vivo peritonitis model. Altogether, our data indicate that adenosine is one of the soluble mediators released by macrophages that mediate engulfment-dependent apoptotic cell suppression of inflammation.

Anti-inflammatory effects of Huang-Lian-Jie-Du decoction, its two fractions and four typical compounds

ETHNOPHARMACOLOGICAL RELEVANCE

Huang-Lian-Jie-Du decoction (HLJDD) (Oren-gedoku-to in Japanese) as a famous traditional Chinese recipe is composed of Rhizoma coptidis, Radix scutellariae, Cortex phellodendri and Fructus gardeniae. It has been used to treat inflammation for nearly two thousand years.

AIM OF THE STUDY

To explore the material base for the anti-inflammatory activity of formula HLJDD, its extract was fractionated on D101 macroporous resin to afford two fractions, HLJDD-1 and HLJDD-2. The whole formula, HLJDD-1 and HLJDD-2, and four typical component compounds were then evaluated for their effects on inflammation-related parameters using lipopolysaccharide (LPS)-induced RAW264.7 cells as a model system.

MATERIALS AND METHODS

The effect of HLJDD on carrageenan-induced mice paw edema was first evaluated. A series of inflammation-related parameters including malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), prostaglandin E(2) (PGE2), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-10 (IL-10) were then measured in LPS-induced RAW264.7 cells treated with HLJDD, its two fractions, and four typical component compounds (geniposide, baicalin, berberine and baicalein).

RESULTS

With the help of principal component analysis (PCA) technique, the data obtained revealed that the two fractions and the major group of compounds in HLJDD (iridoids, flavonoids and alkaloids) complement each other with particular emphasis to synergistically exert anti-inflammatory effects.

CONCLUSIONS

This study demonstrated that HLJDD exhibited anti-inflammatory effect as a "whole", which justified the combined use of the four component herbs forming the compound prescription and suggested quality control of HLJDD based on its three types of components.

Interaction of a specific population of human embryonic stem cell-derived progenitor cells with CD11b+ cells ameliorates sepsis-induced lung inflammatory injury

Human embryonic stem cells differentiated under mesoderm-inducing conditions have important therapeutic properties in sepsis-induced lung injury in mice. Single cell suspensions obtained from day 7 human embryoid bodies (d7EBs) injected i.v. 1 hour after cecal ligation and puncture significantly reduced lung inflammation and edema as well as production of tumor necrosis factor-α and interferon-γ in lungs compared with controls, whereas interleukin-10 production remained elevated. d7EB cell transplantation also reduced mortality to 50% from 90% in the control group. The protection was ascribed to d7EB cell interaction with lung resident CD11b+ cells, and was correlated with the ability of d7EB cells to reduce it also reduced production of proinflammatory cytokines by CD11+ cells, and to endothelial NO synthase–derived NO by d7EB cells, leading to inhibition of inducible macrophage-type NO synthase activation in CD11b+ cells. The protective progenitor cells were positive for the endothelial and hematopoietic lineage marker angiotensin converting enzyme (ACE). Only the ACE+ fraction modulated the proinflammatory profile of CD11b+ cells and reduced mortality in septic mice. In contrast to the nonprotective ACE-cell fraction, the ACE+ cell fraction also produced NO. These findings suggest that an ACE+ subset of human embryonic stem cell–derived progenitor cells has a highly specialized anti-inflammatory function that ameliorates sepsis-induced lung inflammation and reduces mortality.

Anti-inflammatory effects of the willow bark extract STW 33-I (Proaktiv(®)) in LPS-activated human monocytes and differentiated macrophages

INTRODUCTION

Willow bark extract is frequently used in the treatment of painful rheumatological diseases, such as arthritis and back pain. Its effect has been attributed to its main component salicin, but pharmacological studies have shown that the clinical efficacy of the willow bark extract cannot be explained by its salicin content alone. Therefore different modes of action have been suggested for the anti-inflammatory effect of willow bark extract. Here, we report in vitro data revelling the effect and mode of action of the aqueous willow bark extract STW 33-I as well as a water-soluble fraction (fraction E [Fr E]) in comparison with well-known non-steroidal anti-inflammatory drugs (NSAIDs) like aspirin (ASA) and diclofenac (Diclo) on pro-inflammatorily activated human monocytes and differentiated macrophages.

RESULTS

STW 33-I and the water-soluble Fr E showed concentration-dependent and significant anti-inflammatory effects in lipopolysaccharide-activated monocytes. Both inhibited the intracellular protein expression of tumour necrosis factor-alpha (TNFα) as well as the mRNA expression of TNFα and cyclooxygenase 2 (COX-2), and the release of nitric oxide (NO). In addition, apoptosis of pro-inflammatorily activated monocytes was induced. Furthermore, treatment of activated macrophages with STW 33-I inhibited the nuclear translocation of the p65 subunit of the nuclear transcription factor-kappa B (NF-κB p65).

CONCLUSIONS

The present in vitro investigations suggest a significant anti-inflammatory activity of willow bark water extract STW 33-1 and of its water-soluble fraction by inhibiting pro-inflammatory cytokines (TNFα), COX-2 and nuclear translocation of the transcription factor NF-κB in pro-inflammatorily activated monocytes. Our results provide further evidence for the therapeutic use of STW 33-I in inflammation-related disorders.

Sepsis, leukocytes, and nitric oxide (NO): an intricate affair

Sepsis is exceedingly burdensome for hospital intensive care unit caregivers, and its incidence, as well as sepsis-related deaths, is increasing steadily. Sepsis is characterized by a robust increase in NO production throughout the organism that is driven by iNOS. Moreover, NO is an important factor in the development of septic shock and is synthesized by NOS, an enzyme expressed by a variety of cells, including vascular endothelium, macrophages, and neutrophils. However, the effects of NO on leukocyte functions, and the underlying mechanisms, are relatively unknown. Thus, the present review focuses on the effects of NO and its derivatives on cells of the immune system. Experimental evidences discussed herein show that NO induces posttranslational modifications of key proteins in targeted processes with the potential of deterring cellular physiology. Consequently, the manipulation of NO distribution in septic patients, used in conjunction with conventional treatments aimed at restoring normal immune functions, may represent a valuable therapeutic strategy.

Over-expression of caveolin-1 aggravate LPS-induced inflammatory response in AT-1 cells via up-regulation of cPLA2/p38 MAPK

OBJECTIVE AND DESIGN

The aim of this study was to study the effect of caveolin-1 on the cytosolic phospholipase A2 (cPLA2), p38 mitogen-activated protein kinase (p38 MAPK) and nuclear factor kappaB (NF-kappaB) in mouse lung alveolar type-1 cells' (AT-1 cells) inflammatory response induced by LPS.

MATERIALS AND METHODS

Gene clone technique was used to over-express caveolin-1 in AT-1 cells by lentivirus vector. The level of tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), cPLA2, p38 MAPK and NF-kappaB was measured by ELISA, western blotting and EMSA.

TREATMENT

AT-1 cells were treated with LPS.

RESULTS

Over-expression of caveolin-1 not only increased the production of pro-inflammatory cytokine TNF-alpha and IL-6, but also enhanced the expression of the cPLA2, p38 MAPK, and NF-kappaB.

CONCLUSIONS

Our data demonstrated that over-expression of caveolin-1 aggravates the AT-1 injury induced by LPS, involving in modulation of the cPLA2 mediated by the cPLA2/p38 MAPK pathway.

Augmented inducible nitric oxide synthase expression and increased NO production reduce sepsis-induced lung injury and mortality in myeloperoxidase-null mice

The myeloperoxidase (MPO)-hydrogen peroxide-halide system is an efficient oxygen-dependent antimicrobial component of polymorphonuclear leukocyte (PMN)-mediated host defense. However, MPO deficiency results in few clinical consequences indicating the activation of compensatory mechanisms. Here, we determined possible mechanisms protecting the host using MPO(-/-) mice challenged with live gram-negative bacterium Escherichia coli. We observed that MPO(-/-) mice unexpectedly had improved survival compared with wild-type (WT) mice within 5-12 h after intraperitoneal E. coli challenge. Lungs of MPO(-/-) mice also demonstrated lower bacterial colonization and markedly attenuated increases in microvascular permeability and edema formation after E. coli challenge compared with WT. However, PMN sequestration in lungs of both groups was similar. Basal inducible nitric oxide synthase (iNOS) expression was significantly elevated in lungs and PMNs of MPO(-/-) mice, and NO production was increased two- to sixfold compared with WT. Nitrotyrosine levels doubled in lungs of WT mice within 1 h after E. coli challenge but did not change in MPO(-/-) mice. Inhibition of iNOS in MPO(-/-) mice significantly increased lung edema and reduced their survival after E. coli challenge, but iNOS inhibitor had the opposite effect in WT mice. Thus augmented iNOS expression and NO production in MPO(-/-) mice compensate for the lack of HOCl-mediated bacterial killing, and the absence of MPO-derived oxidants mitigates E. coli sepsis-induced lung inflammation and injury.

Pretreatment with pro- and synbiotics reduces peritonitis-induced acute lung injury in rats

BACKGROUND

To study whether enteral pretreatment with a synbiotic composition of lactic acid bacteria and bioactive fibers can reduce peritonitis-induced lung neutrophil infiltration and tissue injury in rats.

MATERIALS AND METHODS

Rats were divided into five groups, and subjected to induction of peritonitis-induced lung injury using a cecal ligation and puncture model (CLP). All animals were pretreated for 3 weeks prior the CLP by daily gavage with either (1) a synbiotic composition (10(10) CFU of Pediococcus pentosaceus 5-33:3, 10(10) CFU of Leuconostoc mesenteroides 77:1, 10(10) CFU of L. paracasei subspecies paracasei, 10(10) CFU of L. plantarum 2362 plus fermentable fibers), (2) fermentable fibers alone, (3) nonfermentable fibers, (4) a probiotic composition (10(10) CFU of P. pentosaceus 5-33:3, 10(10) CFU of L. mesenteroides 77:1, 10(10) CFU of L. paracasei subsp. paracasei, 10(10) CFU of L. plantarum 2,362), or (5) a heat-killed probiotic composition. All animals were killed 24 hours after CLP and lung tissue samples were studied for degree of neutrophil infiltration and levels of tumor necrosis factor (TNF)-alpha, Interleukin (IL)-1beta. In addition the lung wet-to-dry tissue weight ratio, the myeloperoxidase activity, and malondialdehyde content were also assessed.

RESULTS

No mortality was encountered in any of the groups. Histologic signs of lung injury (number of neutrophils and TNF-alpha, IL-1beta staining) were observed in all groups except the synbiotic and probiotic treated groups. Myeloperoxidase activity and malondialdehyde content were significantly lower in the two lactobacillus- pretreated groups, with no difference between them. Heavy infiltration of lung tissue with neutrophils was observed only in fiber-treated (302.20 +/- 7.92) and placebo-treated (266.90 +/- 8.92) animals. This was totally abolished in the synbiotic-treated group (34.40 +/- 2.49). Lung edema (wet-to-dry lung weight ratio) was significantly reduced in the synbiotic-treated group (4.92 +/- 0.13 vs. 5.07 +/- 0.08 and 5.39 +/- 0.10, respectively).

CONCLUSION

Three weeks of preoperative enteral administration of a synbiotic composition reduced peritonitis-induced acute lung injury in rats in a CLP model.

Temporal dynamics of gene expression in the lung in a baboon model of E. coli sepsis

Background

Bacterial invasion during sepsis induces disregulated systemic responses that could lead to fatal lung failure. The purpose of this study was to relate the temporal dynamics of gene expression to the pathophysiological changes in the lung during the first and second stages of E. coli sepsis in baboons.

Results

Using human oligonucleotide microarrays, we have explored the temporal changes of gene expression in the lung of baboons challenged with sublethal doses of E. coli. Temporal expression pattern and biological significance of the differentially expressed genes were explored using clustering and pathway analysis software. Expression of selected genes was validated by real-time PCR. Cytokine levels in tissue and plasma were assayed by multiplex ELISA. Changes in lung ultrastructure were visualized by electron microscopy. We found that genes involved in primary inflammation, innate immune response, and apoptosis peaked at 2 hrs. Inflammatory and immune response genes that function in the stimulation of monocytes, natural killer and T-cells, and in the modulation of cell adhesion peaked at 8 hrs, while genes involved in wound healing and functional recovery were upregulated at 24 hrs.

Conclusion

The analysis of gene expression modulation in response to sepsis provides the baseline information that is crucial for the understanding of the pathophysiology of systemic inflammation and may facilitate the development of future approaches for sepsis therapy.

Tetrandrine Inhibits Proinflammatory Cytokines, iNOS and COX-2 Expression in Human Monocytic Cells

Tetrandrine (TET), a bis-benzylisoquinoline alkaloid isolated from the dried root of hang-fang-chi (Stephania tetrandra S. Moore), is traditionally used in China for treating inflammation, hypertension and silicosis. In this study, our aim was to examine the anti-inflammatory mechanism of TET through measuring the inducible nitric oxide synthase (iNOS), cyclooxygenase-1, and -2 (COX-1 and COX-2) expression, cytokines (TNF-alpha, IL-4 and IL-8) formation, nitric oxide (NO) release and prostaglandin E2 (PGE2) generation in lipopolysaccharide (LPS)-induced human monocytic (THP-1) cells. Results showed that TET remarkably suppressed the LPS (1 microg/ml) induction of NO release and PGE2 generation. It also significantly attenuated the LPS-induced transcription of proinflammatory cytokines (TNF-alpha, IL-4 and IL-8) in a dose-dependent manner. Furthermore, TET at 100 microM significantly blocked the LPS induction of iNOS and COX-2 expression, but not the COX-1. Taken together, these results suggest that TET exerts anti-inflammatory effects probably through the suppression of COX-2 and iNOS expression.

Delayed inflammatory responses to endotoxin in fibrinogen-deficient mice

Severe inflammation leads to haemostatic abnormalities, such as the development of microvascular thrombi. As a result, ischaemia-related downstream organ damage can occur. The present study demonstrates that mice with a total deficiency of fibrinogen (Fg(-/-)) present with altered responses to challenge with Gram-negative lipopolysaccharide (LPS). Early survival in response to continuous LPS challenge was increased in Fg(-/-) mice and histological findings indicated that this improvement correlated with a lack of fibrin deposition in organs. Neutrophils appeared early in the lungs of challenged wild-type (WT) mice, but occurred in Fg(-/-) mice at later times. This delayed response in Fg(-/-) mice was confirmed by studies that showed a strong dependence on Fg of binding of neutrophils to endothelial cells in the presence of LPS. While cytokines were also elevated in both WT and Fg(-/-) mice, their levels were generally lower at early times in this latter group. The time course of MIP-2 expression correlated with the occurrence of pulmonary leakage after LPS challenge, which was delayed in Fg(-/-) mice. These results suggest that fibrin(ogen) plays a role as an early mediator in the cross-talk between coagulation and inflammation.

Caveolin-1 regulates NF-kappaB activation and lung inflammatory response to sepsis induced by lipopolysaccharide

Caveolin-1, the principal structural and signaling protein of caveolae, is implicated in NO-mediated cell signaling events, but its precise role in inflammation is not well understood. Using caveolin-1-knockout (Cav-1(-/-)) mice, we addressed the role of caveolin-1 in the lung inflammatory response to sepsis induced by i.p. injection of LPS. LPS-challenged wild-type (WT) lungs exhibited significant increases in neutrophil sequestration (approximately 16-fold), lung microvascular permeability K(f,c) (approximately 5.7-fold), and edema formation (approximately 1.6-fold). Compared with WT, Cav-1(-/-) lungs showed marked attenuation of LPS-induced neutrophil sequestration (approximately 11-fold increase) and inhibition of microvascular barrier breakdown and edema formation. Prevention of lung injury in Cav-1(-/-) mice was associated with decreased mortality in response to LPS challenge. To address the basis of the reduced inflammation and injury in Cav-1(-/-) lungs, we examined the role of NO because its plasma concentration is known to be increased in Cav-1(-/-) mice. Cav-1(-/-) mouse lungs demonstrated a significant increase in endothelial NO synthase (eNOS)-derived NO production relative to WT, which is consistent with the role of caveolin-1 as a negative regulator of eNOS activity. Cav-1(-/-) lungs concurrently showed suppression of NF-kappaB activity and decreased transcription of inducible NO synthase and ICAM-1. Coadministration of LPS with the NO synthase inhibitor nitro-L-arginine in Cav-1(-/-) mice prevented the suppression of NF-kappaB activity and restored lung polymorphonuclear leukocyte sequestration in response to LPS challenge. Thus, caveolin-1, through its ability to regulate eNOS-derived NO production, is a crucial determinant of NF-kappaB activation and the lung inflammatory response to LPS.

Nitric oxide inhibits neutrophil migration by a mechanism dependent on ICAM-1: Role of soluble guanylate cyclase

In the present study, we addressed the role of intercellular adhesion molecule type 1 (ICAM-1/CD54) in neutrophil migration to inflammatory site and whether the inhibitory effect of nitric oxide (NO) upon the neutrophil rolling, adhesion and migration involves down-modulation of ICAM-1 expression through a cyclic GMP (cGMP) dependent mechanism. It was observed that neutrophil migration induced by intraperitoneal administration of endotoxin (LPS), carrageenan (Cg) or N-formyl peptide (fMLP) in ICAM-1 deficient (ICAM-1-/-) is similar to that observed in wild type (WT) mice. The treatment of mice with NO synthase (NOS) inhibitors, NG-nitro-l-arginine, aminoguanidine or with a soluble guanylate cyclase (sGC) inhibitor, ODQ enhanced LPS- or Cg-induced neutrophil migration, rolling and adhesion on venular endothelium. These parameters induced by LPS were also enhanced by 1400 W, a specific iNOS inhibitor, treatment. On the other hand, the treatment of the mice with S-nitroso-N-acetylpenicillamine (SNAP), an NO donor, reduced these parameters induced by LPS or Cg by a mechanism sensitive to ODQ pretreatment. The NOS inhibitors did not enhance LPS-, Cg- or fMLP-induced migration and adhesion in ICAM-1-/- mice. Moreover, genetic (iNOS-/- mice) or pharmacological inhibition of NOS or of sGC enhanced LPS-induced ICAM-1 expression on mesenteric microcirculation vessels of WT mice. By contrast, SNAP reduced the ICAM-1 expression by a mechanism dependent on cGMP. In conclusion, the results suggest that although during inflammation, ICAM-1 does not contribute to neutrophil migration, it is necessary for the down-modulatory effect of inflammation-released NO on the adhesion and transmigration of neutrophils. Moreover, these NO effects are mediated via cGMP.

A suppressive role of nitric oxide in MIP-2 production by macrophages upon coculturing with apoptotic cells

Macrophages phagocytose apoptotic cells without causing neutrophil infiltration in vivo under physiological conditions. Our recent study, however, showed that macrophages produce IL-8 or MIP-2, a murine IL-8 homologue, upon coculturing with apoptotic cells, indicating that there must be unknown mechanisms for preventing IL-8 or MIP-2 production. As activated macrophages produce NO to regulate inflammation, we examined the NO production by macrophages upon coculturing with apoptotic or necrotic cells and explored the role of NO in MIP-2 production. NO was produced on coculturing with early apoptotic cells much more significantly than with late apoptotic or necrotic cells. On the contrary, MIP-2 was produced on coculturing with late apoptotic or necrotic cells much more significantly than with early apoptotic cells. N(G)-Nitro-L-arginine methyl ester, an inhibitor of NO synthase, or 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, a scavenger of NO, augmented MIP-2 production on coculturing with early apoptotic cells. The addition of N-ethylethanamine:1,1-diethyl-2-hydroxy-2-nitrosohydrazine [1:1], a donor of NO, conversely, caused suppression of MIP-2 production on coculturing with late apoptotic cells. These results suggest an important role of NO for preventing MIP-2 production by macrophages upon coculturing with early apoptotic cells.

Effects of macrophage inducible nitric oxide synthase in murine septic lung injury

Inducible nitric oxide synthase (iNOS) contributes importantly to septic pulmonary protein leak in mice with septic acute lung injury (ALI). However, the role of alveolar macrophage (AM) iNOS in septic ALI is not known. Thus we assessed the specific effects of AM iNOS in murine septic ALI through selective AM depletion (via intratracheal instillation of clodronate liposomes) and subsequent AM reconstitution (via intratracheal instillation of donor iNOS+/+ or iNOS−/− AM). Sepsis was induced by cecal ligation and perforation, and ALI was assessed at 4 h: protein leak by the Evans blue (EB) dye method, neutrophil infiltration via myeloperoxidase (MPO) activity, and pulmonary iNOS mRNA expression via RT-PCR. In iNOS+/+ mice, AM depletion attenuated the sepsis-induced increases in pulmonary microvascular protein leak (0.3 ± 0.1 vs. 1.4 ± 0.1 μg EB·g lung−1·min−1; P < 0.05) and MPO activity (37 ± 4 vs. 67 ± 8 U/g lung; P < 0.05) compared with that shown in non-AM-depleted mice. In AM-depleted iNOS+/+ mice, septic pulmonary protein leak was restored by AM reconstitution with iNOS+/+ AM (0.9 ± 0.3 μg EB·g lung−1·min−1) but not with iNOS−/− donor AM. In iNOS−/− mice, sepsis did not induce pulmonary protein leak or iNOS mRNA expression, despite increased pulmonary MPO activity. However, AM depletion in iNOS−/− mice and subsequent reconstitution with iNOS+/+ donor AM resulted in significant sepsis-induced pulmonary protein leak and iNOS expression. Septic pulmonary MPO levels were similar in all AM-reconstituted groups. Thus septic pulmonary protein leak is absolutely dependent on the presence of functional AM and specifically on iNOS in AM. AM iNOS-dependent pulmonary protein leak was not mediated through changes in pulmonary neutrophil influx.

Salutary effects of estrogen receptor-β agonist on lung injury after trauma-hemorrhage

Although 17β-estradiol (E2) administration after trauma-hemorrhage attenuates lung injury in male rodents, it is not known whether the salutary effects are mediated via estrogen receptor (ER)-α or ER-β. We hypothesized that the salutary effects of E2 lung are mediated via ER-β. Male Sprague-Dawley rats underwent trauma-hemorrhage (mean blood pressure 40 mmHg for 90 min, then resuscitation). E2 (50 μg/kg), ER-α agonist propyl pyrazole triol (PPT; 5 μg/kg), ER-β agonist diarylpropiolnitrile (DPN; 5 μg/kg), or vehicle (10% DMSO) was injected subcutaneously during resuscitation. At 24 h after trauma-hemorrhage or sham operation, bronchoalveolar fluid (BALF) was collected for protein concentration, LDH activity, and nitrate/nitrite and IL-6 levels. Moreover, lung tissue was used for inducible nitric oxide synthase (iNOS) mRNA/protein expression, nitrate/nitrite and IL-6 levels, and wet/dry weight ratio ( n = 6 rats/group). One-way ANOVA and Tukey's test were used for statistical analysis. The results indicated that E2 downregulated lung iNOS expression after trauma-hemorrhage. Protein concentration, LDH activity, and nitrate/nitrite and IL-6 levels in BALF and nitrate/nitrite and IL-6 levels in the lung increased significantly after trauma-hemorrhage; however, administration of DPN but not PPT significantly improved all parameters. Moreover, DPN treatment attenuated trauma-hemorrhage-mediated increase in iNOS mRNA/protein expression in the lung. In contrast, no significant change in the above parameters was observed with PPT. Thus the salutary effects of E2 on attenuation of lung injury are mediated via ER-β, and ER-β-induced downregulation of iNOS likely plays a significant role in the DPN-mediated lung protection after trauma-hemorrhage.

Ventilator-induced lung injury is reduced in transgenic mice that overexpress endothelial nitric oxide synthase

Although mechanical ventilation (MV) is an important supportive strategy for patients with acute respiratory distress syndrome, MV itself can cause a type of acute lung damage termed ventilator-induced lung injury (VILI). Because nitric oxide (NO) has been reported to play roles in the pathogenesis of acute lung injury, the present study explores the effects on VILI of NO derived from chronically overexpressed endothelial nitric oxide synthase (eNOS). Anesthetized eNOS-transgenic (Tg) and wild-type (WT) C57BL/6 mice were ventilated at high or low tidal volume (Vt; 20 or 7 ml/kg, respectively) for 4 h. After MV, lung damage, including neutrophil infiltration, water leakage, and cytokine concentration in bronchoalveolar lavage fluid (BALF) and plasma, was evaluated. Some mice were given N(omega)-nitro-L-arginine methyl ester (L-NAME), a potent NOS inhibitor, via drinking water (1 mg/ml) for 1 wk before MV. Histological analysis revealed that high Vt ventilation caused severe VILI, whereas low Vt ventilation caused minimal VILI. Under high Vt conditions, neutrophil infiltration and lung water content were significantly attenuated in eNOS-Tg mice compared with WT animals. The concentrations of macrophage inflammatory protein-2 in BALF and plasma, as well as plasma tumor necrosis factor-alpha and monocyte chemoattractant protein-1, also were decreased in eNOS-Tg mice. L-NAME abrogated the beneficial effect of eNOS overexpression. In conclusion, chronic eNOS overexpression may protect the lung from VILI by inhibiting the production of inflammatory chemokines and cytokines that are associated with neutrophil infiltration into the air space.

Transport across the endothelium: regulation of endothelial permeability

An important function of the endothelium is to regulate the transport of liquid and solutes across the semi-permeable vascular endothelial barrier. Two cellular pathways controlling endothelial barrier function have been identified. The transcellular pathway transports plasma proteins of the size of albumin or greater via the process of transcytosis in vesicle carriers originating from cell surface caveolae. Specific signalling cues are able to induce the internalisation of caveolae and their movement to the basal side of the endothelium. Caveolin-1, the primary structural protein required for the formation of caveolae, is also important in regulating vesicle trafficking through the cell by controlling the activity and localisation of signalling molecules that mediate vesicle fission, endocytosis, fusion and finally exocytosis. An important function of the transcytotic pathways is to regulate the delivery of albumin and immunoglobulins, thereby controlling tissue oncotic pressure and host-defence. The paracellular pathway induced during inflammation is formed by gaps between endothelial cells at the level of adherens and tight junctional complexes. Paracellular permeability is increased by second messenger signalling pathways involving Ca2+ influx via activation of store-operated channels, protein kinase Calpha (PKCalpha), and Rho kinase that together participate in the stimulation of myosin light chain phosphorylation, actin-myosin contraction, and disruption of the junctions. In this review of the field, we discuss the current understanding of the signalling pathways regulating paracellular and transcellular endothelial permeability.

Adenoviral gene transfer of an NF-κB super-repressor increases collagen deposition in rodent cutaneous wound healing

BACKGROUND

The transcription factor nuclear factor-kappaB (NF-kappaB) plays an essential role in inflammation. To date, no studies have investigated the effect of inhibiting NF-kappaB-mediated inflammation on normal cutaneous wound healing. We tested this by locally administering an adenovirus recombinant that constitutively expresses a super-repressor isoform of inhibitory-kappaB (IkappaB) into rats undergoing a well-established model of dorsal wound healing.

METHODS

Seventy-two Sprague-Dawley rats underwent insertion of a sponge-pump construct into a dorsal subcutaneous pocket. One group of rats received pumps filled with the adenovirus expressing I-kappaB (rAd-Ikappab), a second group received pumps filled with adenovirus expressing green fluorescent protein (GFP) (rAd-gfp), and a third received pumps filled with normal saline (NS). Rats were killed in groups of 6 on days 1, 3, 5 and 7 postoperation. The wound fluid was analyzed for nitrite/nitrate (NOx) and tumor necrosis factor-alpha (TNF-alpha) concentrations. The wound fluid was assayed for hydroxyproline (OHP) content, an index of reparative collagen deposition.

RESULTS

Administration of rAd-Ikappab for 7 days resulted in higher collagen deposition (OHP) compared with the rAd-gfp and NS groups. NOx levels were significantly higher in the rAd-gfp group on day 1 and marginally so on day 5. TNF-alpha quantitation analysis found no significant difference among the 3 groups.

CONCLUSION

IkappaB expression through an adenoviral vector in the cutaneous wound may improve rodent healing, as shown by increased collagen deposition, through decreased inflammation. This mechanism appears to be TNF-alpha independent. Inhibition of NF-kappaB may reduce inflammation by reducing the local NOx concentrations.

l-Arginine prevents air embolism-induced acute lung injury in rats

OBJECTIVE

Pulmonary air embolism, causing vessel obstruction and primary or secondary reactions of blood, can lead to acute lung injury. In addition, nitric oxide has been known to play a key role in various causes of lung injury. In this study we employed the isolated rat lung model to investigate the effects of l-arginine on air embolism-induced lung injury.

DESIGN

Randomized, controlled study.

SETTING

Animal-care facility procedure room.

SUBJECTS

Forty-two adult male Sprague-Dawley rats each weighing 250-350 g.

INTERVENTIONS

Infusion of air at the rate of 0.25 mL/min for 1 min into the pulmonary artery in isolated and perfused rat lung resulted in pulmonary hypertension and lung edema. Air embolism elicited a significant increase in microvascular permeability as measured by the capillary filtration coefficient, lung weight gain, lung weight-to-body weight ratio, pulmonary arterial pressure, and protein concentration of bronchoalveolar lavage fluid.

MEASUREMENTS AND MAIN RESULTS

Pretreatment with L-arginine (4 mmol/L) significantly attenuated the acute lung injury induced by air embolism as shown by a significant decrease in all of the assessed variables but did not alter the pulmonary arterial pressure (p < .05). The protective effect of l-arginine was blocked when N(G)-nitro-L-arginine methyl ester (5 mmol/L) was added. Pretreatment with N(G)-nitro-L-arginine methyl ester exacerbated air embolism-induced lung injury.

CONCLUSIONS

Our findings suggest that L-arginine can prevent air embolism-induced lung injury.

Pathophysiology of polytrauma

Immediate and early trauma deaths are determined by primary brain injuries, or significant blood loss (haemorrhagic shock), while late mortality is caused by secondary brain injuries and host defence failure. First hits (hypoxia, hypotension, organ and soft tissue injuries, fractures), as well as second hits (e.g. ischaemia/reperfusion injuries, compartment syndromes, operative interventions, infections), induce a host defence response. This is characterized by local and systemic release of pro-inflammatory cytokines, arachidonic acid metabolites, proteins of the contact phase and coagulation systems, complement factors and acute phase proteins, as well as hormonal mediators: it is defined as systemic inflammatory response syndrome (SIRS), according to clinical parameters. However, in parallel, anti-inflammatory mediators are produced (compensatory anti-inflammatory response syndrome (CARS). An imbalance of these dual immune responses seems to be responsible for organ dysfunction and increased susceptibility to infections. Endothelial cell damage, accumulation of leukocytes, disseminated intravascular coagulation (DIC) and microcirculatory disturbances lead finally to apoptosis and necrosis of parenchymal cells, with the development of multiple organ dysfunction syndrome (MODS), or multiple organ failure (MOF). Whereas most clinical trials with anti-inflammatory, anti-coagulant, or antioxidant strategies failed, the implementation of pre- and in-hospital trauma protocols and the principle of damage control procedures have reduced post-traumatic complications. However, the development of immunomonitoring will help in the selection of patients at risk of post-traumatic complications and, thereby, the choice of the most appropriate treatment protocols for severely injured patients.

Susceptibility of germfree phagocyte oxidase- and nitric oxide synthase 2-deficient mice, defective in the production of reactive metabolites of both oxygen and nitrogen, to mucosal and systemic candidiasis of endogenous origin

Mice deficient for phagocyte oxidase (Phox) and nitric oxide synthase 2 (NOS2) (gp91phox-/-/NOS2-/-), defective in the production of both reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI), were used to investigate the role of phagocytic cells during mucosal and systemic candidiasis of endogenous origin. The alimentary tracts of germfree mice were colonized with Candida albicans wild type or each of two hyphal signaling-defective mutants (efg1/efg1 and efg1/efg1 cph1/cph1). All Candida-colonized gp91phox-/-/NOS2-/- mice were moribund within 12 to 15 days after oral inoculation. C. albicans wild-type and mutant strains colonized the alimentary tracts equally well and were able to translocate, most likely via Peyer's patches and mesenteric lymph nodes, to the internal organs and trigger the formation of abscesses; however, the wild-type and mutant strains did not survive in the abscessed murine tissues. Surprisingly, there was no significant difference in the ability of peritoneal exudate cells from gp91phox-/-/NOS2-/-, NOS2-/-, gp91phox-/-, or immunocompetent C57BL/6 mice to kill C. albicans in vitro. This suggests that anti-Candida factors other than ROI and RNI can control the growth of C. albicans and that gp91phox-/-/NOS2-/- mice die due to the inability of the host to control its inflammatory response to Candida. Correspondingly, reverse transcription-PCR analysis showed increased expression of the cytokines gamma interferon, tumor necrosis factor alpha, and the chemokines MIP-2 and KC at the site of infection, while interleukin-15 expression remained relatively unchanged between germfree and infected tissues. These studies indicate that defects in ROI and RNI enabled C. albicans to translocate and disseminate to the internal organs, resulting in an uncontrolled immune response, severe pathology, and death; however, ROI and RNI were not required for the killing of phagocytized C. albicans, indicating that other anti-Candida factors either compensate or are sufficient for the killing of phagocytized Candida.

Neurokinins and inflammatory cell iNOS expression in guinea pigs with chronic allergic airway inflammation

In the present study we evaluated the role of neurokinins in the modulation of inducible nitric oxide synthase (iNOS) inflammatory cell expression in guinea pigs with chronic allergic airway inflammation. In addition, we studied the acute effects of nitric oxide inhibition on this response. Animals were anesthetized and pretreated with capsaicin (50 mg/kg sc) or vehicle 10 days before receiving aerosolized ovalbumin or normal saline twice weekly for 4 wk. Animals were then anesthetized, mechanically ventilated, given normal saline or N(G)-nitro-l-arginine methyl ester (l-NAME, 50 mg/kg ic), and challenged with ovalbumin. Prechallenge exhaled NO increased in ovalbumin-exposed guinea pigs (P < 0.05 compared with controls), and capsaicin reduced this response (P < 0.001). Compared with animals inhaled with normal saline, ovalbumin-exposed animals presented increases in respiratory system resistance and elastance and numbers of total mononuclear cells and eosinophils, including those expressing iNOS (P < 0.001). Capsaicin reduced all these responses (P < 0.05) except for iNOS expression in eosinophils. Treatment with l-NAME increased postantigen challenge elastance and restored both resistance and elastance previously attenuated by capsaicin treatment. Isolated l-NAME administration also reduced total eosinophils and mononuclear cells, as well as those cells expressing iNOS (P < 0.05 compared with ovalbumin alone). Because l-NAME treatment restored lung mechanical alterations previously attenuated by capsaicin, NO and neurokinins may interact in controlling airway tone. In this experimental model, NO and neurokinins modulate eosinophil and lymphocyte infiltration in the airways.

Microarray analysis of Aeromonas hydrophila cytotoxic enterotoxin-treated murine primary macrophages

We performed microarray analyses of murine peritoneal macrophages to examine cellular transcriptional responses to a cytotoxic enterotoxin of Aeromonas hydrophila. While 66% of altered genes were common to both primary macrophages and the murine macrophage cell line RAW 264.7, Act caused expression changes of 28 genes specifically in murine peritoneal macrophages.

Carboxypeptidase-mediated enhancement of nitric oxide production in rat lungs and microvascular endothelial cells

Membrane-bound regulatory carboxypeptidases cleave only COOH-terminal basic residues from peptides and proteins. To investigate whether carboxypeptidase-generated arginine can increase nitric oxide (NO) synthesis we perfused rat lungs from animals challenged with LPS or used rat lung microvascular endothelial cells (RLMVEC) stimulated with LPS and IFN-γ, conditions that induced inducible NO synthase (iNOS) expression. Addition of carboxypeptidase substrate furylacryloyl-Ala-Arg (Fa-A-R) or Arg to the lung perfusate increased NO production two- to threefold. The carboxypeptidase inhibitor 2-mercaptomethyl-3-guanidinoethylthiopropanoic acid (MGTA) blocked the effect of Fa-A-R but not free Arg. Lysine, an Arg transport inhibitor, blocked the increase in NO stimulated by Fa-A-R. HPLC analysis showed that Fa-A-R hydrolysis was blocked by MGTA but not lysine. In cytokine-treated RLMVEC, Fa-A-R also stimulated NO production inhibited by MGTA or lysine. Membrane fractions from rat lungs or RLMVEC contained carboxypeptidase M-like activity at neutral pH that increased twofold in RLMVEC treated with LPS + IFN-γ. The kinetics of NO production in RLMVEC was measured with a porphyrinic microsensor. Addition of 1 mM Arg or Fa-A-R to cells preincubated in Arg-free medium resulted in a slowly rising, prolonged (>20 min) NO output. NO production stimulated by Fa-A-R was blocked by MGTA or iNOS inhibitor 1400W. HPLC analysis of Fa-A-R hydrolysis revealed only 3.7 μM Arg was released over 20 min. Thus NO production in RLMVEC is stimulated more efficiently by Arg released from carboxypeptidase substrates than free Arg. These studies reveal a novel mechanism by which the Arg supply for NO production in inflammatory conditions may be maintained.

Pulmonary neutrophil infiltration in murine sepsis: role of inducible nitric oxide synthase

Nitric oxide (NO) derived from inducible NO synthase (iNOS) contributes to the pathophysiology of acute lung injury (ALI). The effect of iNOS on pulmonary neutrophil infiltration in ALI is not known. Thus, we assessed pulmonary microvascular neutrophil sequestration through intravital videomicroscopy and pulmonary neutrophil infiltration, reflected by myeloperoxidase activity and lavage neutrophil counts, after induction of sepsis by cecal ligation/perforation in wild-type (iNOS+/+) versus iNOS-/- mice. Pulmonary microvascular neutrophil sequestration was attenuated in septic iNOS-/- versus iNOS+/+ mice (15 +/- 1 vs. 20 +/- 1 leukocytes per field, p < 0.05), but lavage neutrophil counts were greater in iNOS-/- mice (5.7 +/- 1.5% vs. 0.7 +/- 0.1%, p < 0.05) between 6 and 18 hours after cecal ligation and perforation. When iNOS+/+ bone marrow was transplanted into bone marrow-depleted iNOS-/- mice (+ to - chimeras; iNOS limited to marrow-derived inflammatory cells), septic pulmonary microvascular neutrophil sequestration and lavage neutrophil counts were restored to levels seen in septic iNOS+/+ mice. In contrast, in - to + chimeras, pulmonary neutrophil trafficking was similar to iNOS-/- mice. In vitro cytokine-stimulated neutrophil transendothelial migration was significantly greater for iNOS-/- versus iNOS+/+ neutrophils (7.9 +/- 0.7% vs. 3.8 +/- 0.6%, p < 0.05) but was independent of endothelial iNOS. Thus, neutrophil iNOS-derived NO is an important autocrine modulator of pulmonary neutrophil infiltration in murine sepsis.

Regulatory effects of iNOS on acute lung inflammatory responses in mice

The role of endogenous NO in the regulation of acute lung injury is not well defined. We investigated the effects of inducible nitric oxide synthase (iNOS) and endothelial NOS (eNOS) on the acute inflammatory response in mouse lungs. Acute lung injury was induced by intratracheal instillation of bacterial lipopolysaccharide (LPS) into wild-type (WT) mice and mice deficient in iNOS (iNOS(-/-)) or eNOS (eNOS(-/-)). Endpoints of inflammatory injury were myeloperoxidase (MPO) content and leak of albumin into lung. Inflammatory injury was similar in WT and eNOS(-/-) mice but was substantially increased in iNOS(-/-) mice. Bronchoalveolar lavage (BAL) fluids of iNOS(-/-) and WT mice showed similar levels of CXC chemokines (MIP-2, KC) but enhanced levels of CC chemokines (MCP-1, MCP-3). Increased lung content of MPO in iNOS(-/-) mice was reduced by anti-MCP-1 to values found in WT mice. In vitro stimulation of microvascular endothelial cells with LPS and IFN gamma revealed elevated production of CXC and CC chemokines in cells from iNOS(-/-) mice when compared to endothelial cells from iNOS(+/+) mice. Peritoneal macrophages from iNOS(-/-) donors also revealed increased production of CC chemokines after stimulation with LPS and interferon (IFN gamma). These data indicate that absence of iNOS causes enhanced lung inflammatory responses in mice which may be related to enhanced production of MCP-1 by endothelial cells and macrophages. It appears that iNOS affects the lung inflammatory response by regulating chemokine production.

NF-κB and c-Jun-dependent regulation of macrophage inflammatory protein-2 gene expression in response to lipopolysaccharide in RAW 264.7 cells

Macrophage inflammatory protein-2 (MIP-2) is a mouse C-X-C chemokine that plays an important role in the recruitment of neutrophils. Transcription of the MIP-2 gene is rapidly induced by lipopolysaccharide (LPS) stimulation in cells of macrophage lineage. We show here that the MIP-2 promoter is transcriptionally activated in a macrophage cell line RAW 264.7 by LPS through a sequence located between -450 and -54 and this region contains two copies of activator protein-1 (AP-1) and one copy of nuclear factor-kappaB (NF-kappaB) binding site. A MIP-2 promoter-reporter was activated by ectopical expression of NF-kappaB p65 or c-Jun transcription factors. Inhibition of NF-kappaB nuclear localization by co-expression of a mutant IkappaBalpha protein (IkappaBalpha super repressor, IkappaBalphaSR) blocked LPS-induced transcription from a MIP-2 promoter-reporter construct, showing that NF-kappaB activation is required for MIP-2 gene expression in the LPS-signaling pathway. By deletion analysis of the MIP-2 promoter region, we show that NF-kappaB and c-Jun binding sites are essential for LPS-induced MIP-2 gene expression. Using transient transfection, NF-kappaB and c-Jun transcription factors were found to synergistically activate the MIP-2 promoter. In summary, our data suggest that both NF-kappaB and c-Jun contribute to LPS-induced mouse MIP-2 gene expression in RAW 264.7 cells.

Protein nitration in rat lungs during hyperoxia exposure: a possible role of myeloperoxidase

Several studies have suggested that exposure to hyperoxia causes lung injury through increased generation of reactive oxygen and nitrogen species. The present study was aimed to investigate the effects of hyperoxia exposure on protein nitration in lungs. Rats were exposed to hyperoxia (>95%) for 48, 60, and 72 h. Histopathological analysis showed a dramatic change in the severity of lung injury in terms of edema and hemorrhage between 48- and 60-h exposure times. Western blot for nitrotyrosine showed that several proteins with molecular masses of 29-66 kDa were nitrated in hyperoxic lung tissues. Immunohistochemical analyses indicate nitrotyrosine staining of alveolar epithelial and interstitial regions. Furthermore, immunoprecipitation followed by Western blot revealed the nitration of surfactant protein A and t1alpha, proteins specific for alveolar epithelial type II and type I cells, respectively. The increased myeloperoxidase (MPO) activity and total nitrite levels in bronchoalveolar lavage and lung tissue homogenates were observed in hyperoxic lungs. Neutrophils and macrophages isolated from the hyperoxia-exposed rats, when cocultured with a rat lung epithelial L2 cell line, caused a significant protein nitration in L2 cells. Inclusion of nitrite further increased the protein nitration. These studies suggest that protein nitration during hyperoxia may be mediated in part by MPO generated from activated phagocytic cells, and such protein modifications may contribute to hyperoxia-mediated lung injury.

Regulation of macrophage inflammatory protein-2 gene expression in response to oligodeoxynucleotide containing CpG motifs in RAW 264.7 cells

Macrophage inflammatory protein-2 (MIP-2) is a mouse C-X-C chemokine that plays an important role in the recruitment of neutrophils. The unregulated production of MIP-2 has been associated with inflammatory diseases such as arthritis, glomerulonephritis, and sepsis. We have shown that the MIP-2 gene expression is transcriptionally activated by synthetic oligodeoxynucleotide (ODN) containing unmethylated CpG dinucleotides in the context of particular base sequences (CpG-ODN) in a CpG sequence-dependent manner. Inhibition of NF-kappaB nuclear localization by coexpression of a mutant IkappaBalpha protein blocked CpG-ODN-induced transcription from a MIP-2 promoter-reporter construct, showing that NF-kappaB activation is required for MIP-2 gene expression in the CpG-ODN-signaling pathway. We also provided evidence that NF-kappaB and c-Jun contributes to the expression of MIP-2 gene in response to CpG-ODN, since ectopical expression of NF-kappaB and c-Jun in RAW 246.7 cells leads to dramatically increase the ability of CpG-ODN 1826(S) in MIP-2 promoter activity. These results perhaps give more insights into understanding of the mechanisms involved in transient inflammatory arthritis induction by CpG-ODN treatment.

Host innate defenses in the lung: the role of cytokines

PURPOSE OF REVIEW

The lung has a unique relationship with the environment. Through evolution the lung has developed strategies to defend itself from microbial invasion. As we encounter increasing multidrug-resistant microorganisms, we need to further our knowledge of innate defense systems in order to design novel strategies to deal with these microbes without inducing over-exuberant inflammation and lung injury.

RECENT FINDINGS

The development of lung innate immunity requires microbial molecular pattern recognition by the recently described Toll like receptors, the release of early response cytokines that further activate the 'master switch', nuclear factor-kappaB, leading to amplified host defense to invading microbes. A balance of Type 1 and Type 2 cytokines modulates the intensity of innate immunity. Cytokines/chemokines orchestrate the polarization and transition of innate to adaptive immunity.

SUMMARY

The elucidation of the pathways involved in innate immunity and factors controlling the transition to adaptive immunity will improve our understanding of the host response to infection and improve our ability to design new therapies for the treatment of infectious disease.

Nitric oxide donors inhibit luciferase expression in a promoter-independent fashion

Nitric oxide (NO) is an important molecule with diverse bio-messenger functions including regulation of gene expression. Transcriptional studies using sensitive luciferase reporter systems have suggested that NO inhibits the promoter activity of a variety of genes. Here we report that NO donors (sodium nitroprusside, 2',2'-(hydroxynitrosohydrazono)bis-ethanimine, and (+/-)-(E)-4-ethyl-2-[(Z)-hydroxyimino]-5-nitro-3-hexen-1-yl-nicotinamide) decrease luciferase activity in a promoter-independent fashion in both viral and eukaryotic promoters, with a reduction to nearly 50% in the presence of 100 microm NO donor. Addition of an SV40 enhancer downstream of the luciferase coding region shifted NO donor inhibition to the right, with inhibition at approximately 300 microm. In contrast, when studied in a chloramphenicol acetyltransferase reporter, two promoters indicating inhibition by NO were unaffected. The decrease in luciferase activity was not caused by NO suppression of the luciferase enzyme. Real-time PCR data showed that luciferase mRNA half-life decreased by nearly half in the presence of NO donor (from 75 to 45 min). The SV40 enhancer prolonged luciferase mRNA half-life and somewhat blunted the NO effect. Our data suggest that exogenous NO inhibits luciferase activity in a dose-dependent manner through decreasing luciferase mRNA stability. Thus, the use of luciferase reporter systems to study transcriptional regulation by NO should be attempted with caution.