Multiple controls in inflammation. Extracellular and intracellular phospholipase A2, inducible and constitutive cyclooxygenase, and inducible nitric oxide synthase

A clindamycin acetylated derivative with reduced antibacterial activity inhibits articular hyperalgesia and edema by attenuating neutrophil recruitment, NF-κB activation and tumor necrosis factor-α production

We recently demonstrated that clindamycin exhibits activities in acute and chronic models of pain and inflammation. In the present study, we investigated the effects of clindamycin and a clindamycin acetylated derivative (CAD) in models of acute joint inflammation and in a microbiological assay. Joint inflammation was induced in mice by intraarticular (i.a.) injection of zymosan or lipopolysaccharide (LPS). Clindamycin or CAD were administered via the intraperitoneal route 1 h before zymosan or LPS. Paw withdrawal threshold, joint diameter, histological changes, neutrophil recruitment, tumor necrosis factor-α (TNF-α) production and phosphorylation of the IκBα and NF-κB/p65 were evaluated. In vitro assays were used to measure the antibacterial activity of clindamycin and CAD and also their effects on zymosan-induced TNF-α production by RAW264.7 macrophages. Clindamycin exhibited activity against Staphylococcus aureus and Salmonella Typhimurium ATCC® strains at much lower concentrations than CAD. Intraarticular injection of zymosan or LPS induced articular hyperalgesia, edema and neutrophil infiltration in the joints. Zymosan also induced histological changes, NF-κB activation and TNF-α production. Responses induced by zymosan and LPS were inhibited by clindamycin (200 and 400 mg/kg) or CAD (436 mg/kg). Both clindamycin and CAD inhibited in vitro TNF-α production by macrophages. In summary, we provided additional insights of the clindamycin immunomodulatory effects, whose mechanism was associated with NF-κB inhibition and reduced TNF-α production. Such effects were extended to a clindamycin derivative with reduced antibacterial activity, indicating that clindamycin derivatives should be investigated as candidates to drugs that could be useful in the management of inflammatory and painful conditions.

Eicosanoid Biosynthesis in Male Reproductive Development: Effects of Perinatal Exposure to NSAIDs and Analgesic Drugs

Increasing rates of infertility associated with declining sperm counts and quality, as well as increasing rates of testicular cancer are contemporary issues in the United States and abroad. These conditions are part of the Testicular Dysgenesis Syndrome, which includes a variety of male reproductive disorders hypothesized to share a common origin based on disrupted testicular development during fetal and neonatal stages of life. Male reproductive development is a highly regulated and complex process that relies on an intricate coordination between germ, Leydig, and Sertoli cells as well as other supporting cell types, to ensure proper spermatogenesis, testicular immune privilege, and endocrine function. The eicosanoid system has been reported to be involved in the regulation of fetal and neonatal germ cell development as well as overall testicular homeostasis. Moreover, non-steroidal anti-inflammatory drugs (NSAIDs) and analgesics with abilities to block eicosanoid synthesis by targeting either or both isoforms of cyclooxygenase enzymes, have been found to adversely affect male reproductive development. This review will explore the current body of knowledge on the involvement of the eicosanoid system in male reproductive development, as well as discuss adverse effects of NSAIDs and analgesic drugs administered perinatally, focusing on toxicities reported in the testis and on major testicular cell types. Rodent and epidemiological studies will be corroborated by findings in invertebrate models for a comprehensive report of the state of the field, and to add to our understanding of the potential long-term effects of NSAID and analgesic drug administration in infants.

Pharmaconutrition strategy to resolve SARS-CoV-2-induced inflammatory cytokine storm in non-alcoholic fatty liver disease: Omega-3 long-chain polyunsaturated fatty acids

Inflammation is one of the primary factors associated with the causation and/or progression of several lifestyle disorders, including obesity, type 2 diabetes and non-alcoholic fatty liver disease (NAFLD). NAFLD is a spectrum of disorders, and starts with simple steatosis, progresses to non-alcoholic steatohepatitis, and then advances to fibrosis, cirrhosis and finally, hepatocellular carcinoma, due to perpetual cycles of insults caused by inflammation and other cellular stress. Emerging evidence has documented that patients with NAFLD have severe coronavirus disease 2019 (COVID-19), and patients with COVID-19 have a higher liver injury and mortality. Although the exact cause or mechanism is not known, inflammatory cytokine storm is a characteristic feature of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and is known to be associated with higher mortality among COVID-19 patients. Therefore, the COVID-19 pandemic seems to be a major concern in NAFLD patients, who have contracted SARS-CoV-2 infection and develop COVID-19. This is evident in patients at any stage of the NAFLD spectrum, as the inflammatory cytokine storm may cause and/or aggravate the progression or severity of NAFLD. Thus, there is a need for resolution of the inflammatory cytokine storm in these patients. A large body of evidence has demonstrated the efficacy of omega-3 long-chain polyunsaturated fatty acids (ω-3 LCPUFA) in NAFLD conditions, due to their anti-inflammatory, immunomodulatory and anti-viral properties. Therefore, intervention with ω-3 LCPUFA, an effective pharmaconutrient along with the standard treatment for COVID-19 may be useful in the management of the NAFLD spectrum in COVID-19 patients with pre-existing NAFLD conditions by resolving the inflammatory cytokine storm and thereby attenuating its progression. Although there are challenges in implementation, optimistically they can be circumvented and the pharmaconutrition strategy may be potentially helpful in tackling both the pandemics; NAFLD and COVID-19 at least in this subset of patients.

Ginkgo Biloba Extract (Egb 761) Modulates Bleomycin-induced Acute Lung Injury in Rats

The effect of Ginkgo biloba extract (EGb 761) on bleomycin (BLM)-induced acute lung injury was studied in rats. The responsiveness of isolated pulmonary arterial rings to 5-hydroxytryptamine (5-HT) as well as the levels of some relevant biochemical markers in the lung tissue were taken as evidence for the acute lung injury. BLM was given intraperitoneally at a dose of 15 mg/kg/day for five consecutive days. It was found that BLM treatment attenuated the vasoconstrictor effect of 5-HT on the isolated pulmonary arteries. In lung tissues BLM also elevated the level of lipid peroxides and enhanced the activity of glutathione peroxidase. On the other hand, the level of glutathione and the activity of alkaline phosphatase were reduced. Body weight, lung weight and tissue glutathione-S-transferase activity were, however, not altered. Oral administration of EGb 761 at a dose of 100 mg/kg/day for five consecutive days did not alter any of the chosen biochemical parameters in the lung tissue except for a slight reduction in alkaline phosphatase activity. However, treatment with EGb 761 reduced the responsiveness of the pulmonary artery to 5-HT. Administration of EGb 761 (100 mg/kg/day; po) two hours prior to BLM (15 mg/kg/day; ip), for five consecutive days blunted the occurrence of further reduction in the vasoconstrictor response of the pulmonary artery to 5-HT. Furthermore, EGb 761 tended to normalize BLM-induced alterations in the measured biochemical markers in the lung tissue. The apparent modulatory influence of EGb 761 on BLM-induced acute lung injury stems, at least in part, from its beneficial free radical scavenging properties that provide the extract with antioxidant activity.

In Vitro Anti-Inflammatory and Cytotoxic Effects of Aqueous Extracts from the Edible Sea Anemones Anemonia sulcata and Actinia equina

Marine invertebrates have been attracting the attention of researchers for their application in nutrition, agriculture, and the pharmaceutical industry, among others. Concerning sea anemones (Cnidaria), little is known regarding their metabolic profiles and potential value as a source of pharmacologically-active agents. In this work, the chemical profiles of two species of sea anemones Actinia equina and Anemonia sulcata, were studied by high-performance liquid chromatography with diode-array detection (HPLC-DAD) and its impact upon immune and gastric cells was evaluated. In both species, the methylpyridinium alkaloid homarine was the major compound in aqueous extracts. The extracts were effective in reducing lipopolysaccharide (LPS)-induced levels of nitric oxide (NO) and intracellular reactive oxygen species (ROS) in a macrophage model of inflammation. Both the extracts and the alkaloid homarine were effective in inhibiting phospholipase A₂ (PLA₂), a pivotal enzyme in the initial steps of the inflammatory cascade. In order to mimic the oral consumption of these extracts; their effect upon human gastric cells was evaluated. While no caspase-9 activation was detected, the fact that the endoplasmic reticulum-resident caspase-4, and also caspase-3, were activated points to a non-classical mechanism of apoptosis in human gastric cells. This work provides new insights on the toxicity and biological potential of sea anemones increasingly present in human nutrition.

Multivalent nanoparticle networks enable point-of-care detection of human phospholipase-A2 in serum

A rapid and highly sensitive point-of-care (PoC) lateral flow assay for phospholipase A2 (PLA2) is demonstrated in serum through the enzyme-triggered release of a new class of biotinylated multiarmed polymers from a liposome substrate. Signal from the enzyme activity is generated by the adhesion of polystreptavidin-coated gold nanoparticle networks to the lateral flow device, which leads to the appearance of a red test line due to the localized surface plasmon resonance effect of the gold. The use of a liposome as the enzyme substrate and multivalent linkers to link the nanoparticles leads to amplification of the signal, as the cleavage of a small amount of lipids is able to release a large amount of polymer linker and adhesion of an even larger amount of gold nanoparticles. By optimizing the molecular weight and multivalency of these biotinylated polymer linkers, the sensitivity of the device can be tuned to enable naked-eye detection of 1 nM human PLA2 in serum within 10 min. This high sensitivity enabled the correct diagnosis of pancreatitis in diseased clinical samples against a set of healthy controls using PLA2 activity in a point-of-care device for the first time.

Analgesic and Anti-Inflammatory Activities of Rosa taiwanensis Nakai in Mice

In this study, we evaluated the analgesic and anti-inflammatory activities of a 70% ethanol extract from Rosa taiwanensis Nakai (RTEtOH). The analgesic effect was determined using acetic acid-induced writhing response and formalin test. The anti-inflammatory activity was evaluated by λ-carrageenan-induced paw edema in mice. The anti-inflammatory mechanism of RTEtOH was examined by measuring the levels of cyclooxygenase-2 (COX-2), nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, and malondialdehyde (MDA) in the paw edema tissue and the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GRd) in the liver tissue. The betulinic acid and oleanolic acid contents of RTEtOH were assayed by HPLC. The results showed that RTEtOH decreased the acetic acid-induced writhing responses (1.0 g/kg) and the late phase of the formalin-induced licking time (0.5 and 1.0 g/kg). In the anti-inflammatory models, RTEtOH (0.5 and 1.0 g/kg) reduced the paw edema at 3, 4, and 5 h after λ-carrageenan administration. Moreover, the anti-inflammatory mechanisms might be due to the decreased levels of COX-2, TNF-α, IL-1β, and IL-6, as well as the inhibition of NO and MDA levels through increasing the activities of SOD, GPx, and GRd. The contents of two active compounds, betulinic acid and oleanolic acid, were quantitatively determined. This study demonstrated the analgesic and anti-inflammatory activities of RTEtOH and provided evidence to support its therapeutic use in inflammatory diseases.

Harpalycin 2 inhibits the enzymatic and platelet aggregation activities of PrTX-III, a D49 phospholipase A2 from Bothrops pirajai venom

Background

Harpalycin 2 (HP-2) is an isoflavone isolated from the leaves of Harpalyce brasiliana Benth., a snakeroot found in northeast region of Brazil and used in folk medicine to treat snakebite. Its leaves are said to be anti-inflammatory. Secretory phospholipases A₂ are important toxins found in snake venom and are structurally related to those found in inflammatory conditions in mammals, as in arthritis and atherosclerosis, and for this reason can be valuable tools for searching new anti-phospholipase A₂ drugs.

Methods

HP-2 and piratoxin-III (PrTX-III) were purified through chromatographic techniques. The effect of HP-2 in the enzymatic activity of PrTX-III was carried out using 4-nitro-3-octanoyloxy-benzoic acid as the substrate. PrTX-III induced platelet aggregation was inhibited by HP-2 when compared to aristolochic acid and p-bromophenacyl bromide (p-BPB). In an attempt to elucidate how HP-2 interacts with PrTX-III, mass spectrometry, circular dichroism and intrinsic fluorescence analysis were performed. Docking scores of the ligands (HP-2, aristolochic acid and p-BPB) using PrTX-III as target were also calculated.

Results

HP-2 inhibited the enzymatic activity of PrTX-III (IC₅₀ 11.34 ± 0.28 μg/mL) although it did not form a stable chemical complex in the active site, since mass spectrometry measurements showed no difference between native (13,837.34 Da) and HP-2 treated PrTX-III (13,856.12 Da). A structural analysis of PrTX-III after treatment with HP-2 showed a decrease in dimerization and a slight protein unfolding. In the platelet aggregation assay, HP-2 previously incubated with PrTX-III inhibited the aggregation when compared with untreated protein. PrTX-III chemical treated with aristolochic acid and p-BPB, two standard PLA₂ inhibitors, showed low inhibitory effects when compared with the HP-2 treatment. Docking scores corroborated these results, showing higher affinity of HP-2 for the PrTX-III target (PDB code: 1GMZ) than aristolochic acid and p-BPB. HP-2 previous incubated with the platelets inhibits the aggregation induced by untreated PrTX-III as well as arachidonic acid.

Conclusion

HP-2 changes the structure of PrTX-III, inhibiting the enzymatic activity of this enzyme. In addition, PrTX-III platelet aggregant activity was inhibited by treatment with HP-2, p-BPB and aristolochic acid, and these results were corroborated by docking scores.

Dengue virus infection mediates HMGB1 release from monocytes involving PCAF acetylase complex and induces vascular leakage in endothelial cells

High mobility group box 1 (HMGB1) protein is released from cells as a pro-inflammatory cytokine in response to an injury or infection. During dengue hemorrhagic fever (DHF)/dengue shock syndrome (DSS), a number of pro-inflammatory cytokines are released, contributing to disease pathogenesis. In this study, the release of HMGB1 from human myelogenous leukemia cell line K562 and primary peripheral blood monocytes (PBM) cells was examined during dengue virus (DV)-infection. HMGB1 was shown to translocate from cell nuclei to the cytoplasm in both K562- and PBM-infected cells. The translocation of HMGB1 from the nucleus to the cytoplasm was shown to be mediated by the host cell p300/CBP-associated factor (PCAF) acetylase complex in K562 cells. In addition, DV capsid protein was observed to be the putative viral protein in actuating HMGB1 migration from the nucleus to cytoplasm through the involvement of PCAF acetylase. HMGB1 was released from DV-infected K562 cells into the extracellular milieu in a multiplicity of infection (M.O.I.)-independent manner and its release can be inhibited by the addition of 1–5 mM of ethyl pyruvate (EP) in a dose-dependent manner. Application of DV-infected K562 cell culture supernatants to primary endothelial cells induced vascular permeability. In contrast, supernatants from DV-infected K562 cells treated with EP or HMGB1 neutralizing antibody were observed to maintain the structural integrity of the vascular barrier.

Analgesic and anti-inflammatory activities of the methanol extract of Elaeagnus oldhamii Maxim. in mice

We investigated possible mechanisms of analgesic and anti-inflammatory activities of the methanol extract from the leaf of Elaeagnus oldhamii Maxim. (EO(MeOH)). EO(MeOH) was evaluated for its analgesic activity in acetic acid-induced writhing response and formalin test, and anti-inflammatory effect was examined by λ-carrageenan-induced paw edema assay. We detected the activities of GPx, GRd and SOD in the liver, and the levels of inflammatory mediators including IL-1β, IL-6, TNF-α, COX-2, MDA and NO in the edema paw to investigate the mechanism of action against inflammation. Total polyphenol, flavonoid and flavanol contents of EO(MeOH) were detected to explore its antioxidant activities. Results showed that, in the analgesic test, EO(MeOH) decreased acetic acid-induced writhing response and the licking time in the late phase of formalin test. In the anti-inflammatory test, EO(MeOH) decreased paw edema at the 2nd, 3rd, 4th and 5th h after λ-carrageenan had been injected. EO(MeOH) increased the activities of SOD and GPx in liver tissue and decreased MDA, NO, IL-1β, IL-6, TNF-α and COX-2 levels in paw edema tissue at the 3rd h after λ-carrageenan-induced inflammatory reaction. EO(MeOH) exhibited abundant polyphenol, flavonoid and flavanol contents. In HPLC fingerprint test of EO(MeOH), two index ingredients, ursolic acid and pomolic acid, were isolated from EO(MeOH) and were exhibited in HPLC chromatographic analysis. The results demonstrated analgesic and anti-inflammatory effects of EO(MeOH). It was indicated that the anti-inflammatory mechanism of EO(MeOH) may be due to declined levels of NO and MDA in the edema paw through increasing the activities of SOD, GPx and GRd in the liver. Additionally, EO(MeOH) decreased IL-1β, IL-6, TNF-α and COX-2 levels in the edema paw. The results suggested its value in future development of herbal medicine for the treatment of inflammatory diseases.

Modulation of the pharmacological activities of secretory phospholipase A2 from Crotalus durissus cascavella induced by naringin

In this work we have characterized the action of the naringin, a flavonoid found in grapefruit and known for its various pharmacological effects, which include antioxidant blood lipid lowering and anticancer activity, on the structure and biochemical activities of a secretory phospholipase A (sPLA2) from Crotalus durissus cascavella, an important protein involved in the releasinge of arachidonic acid in phospholipid membranes. sPLA2 was incubated with naringin (mol:mol) at 37 °C and a discrete reduction in the UV scanning signal and a modification of the circular dichroism spectra were observed after treatment with naringin, suggesting modifications of the secondary structure of the protein. This flavonoid was able to decrease enzymatic activity and some pharmacological effects, such as myonecrosis, platelet aggregation, and neurotoxic activity caused by sPLA2, however, the inflammatory effect was not affected by naringin. In addition, small angle X-ray scattering (SAXS) data were collected for sPLA2 and naringin-treated sPLA2 to evaluate possible modifications of the protein structure. These structural investigations have shown that sPLA2 is an elongated dimer in solution and after treatment with naringin a conformational change in the dimeric configuration was observed. Our results suggest that structural modification may be correlated with the loss of enzymatic activity and alterations in pharmacological properties.

Effect of umbelliferone (7-hydroxycoumarin, 7-HOC) on the enzymatic, edematogenic and necrotic activities of secretory phospholipase A2 (sPLA2) isolated from Crotalus durissus collilineatus venom

Flavonoids, coumarins and other polyphenolic compounds are powerful antioxidants both in hydrophilic and lipophylic environments with diverse pharmacological properties including anti-inflammatory activity. Despite being widely used as powerful therapeutic agents for blood coagulation disorders, more specifically to control some serine protease enzymes, the mechanism of anti-inflammatory activity of coumarins is unknown, unlike that of flavonoids. Although their controlling effect on serine proteases is well acknowledged, their action on secretory phospholipase A2 (sPLA2) remains obscure. The present study describes the interaction between umbelliferone (7-HOC) and the sPLA2 from Crotalus durissus collilineatus venom. In vitro inhibition of sPLA2 enzymatic activity by 7-HOC was estimated using 4N3OBA as substrate, resulting in an irreversible decrease in such activity proportional to 7-HOC concentration. The biophysical interaction between 7-HOC and sPLA2 was examined by fluorescent spectral analysis and circular dichroism studies. Results from both techniques clearly showed that 7-HOC strongly modified the secondary structure of this enzyme and CD spectra revealed that it strongly decreased sPLA2 alpha-helical conformation. In addition, two-dimensional electrophoresis indicated an evident difference between HPLC-purified native and 7-HOC-treated sPLA2s, which were used in pharmacological experiments to compare their biological activities. In vivo anti-inflammatory activity was assessed by the sPLA2-induced mouse paw edema model, in which 7-HOC presented an effect similar to those of dexamethasone and cyproheptadine against the pro-inflammatory effect induced by native sPLA2 on the mouse paw edema, mast cell degranulation and skin edema. On the other hand, 7-HOC exhibited a more potent inhibitory effect on sPLA2 than that of p-bromophenacyl bromide (p-BPB). Our data suggest that 7-HOC interacts with sPLA2 and causes some structural modifications that lead to a sharp decrease or inhibition of the edematogenic and myotoxic activities of this enzyme, indicating its potential use to suppress inflammation induced by sPLA2 from the snake venom.

Analgesic and anti-inflammatory activities of ethanol root extract of Mahonia oiwakensis in mice

AIMS OF THE STUDY

This study investigated the anti-inflammatory and analgesic activities, and protoberberine alkaloid contents of ethanol extract of MO roots (MOR(EtOH)).

MATERIALS AND METHODS

The analgesic activity of MOR(EtOH) was determined using acetic acid-induced writhing response and formalin test. The anti-inflammatory activity of MOR(EtOH) was determined using the lambda-carrageenan-induced paw oedema model. The protoberberine alkaloid contents of MOR(EtOH) were identified by high-performance liquid chromatography (HPLC).

RESULTS

MOR(EtOH) (100 and 500 mg/kg) decreased the acetic acid-induced writhing responses and licking times of the second phase in the formalin test. Moreover, carrageenan-induced paw oedema was significantly reduced in a dose-dependent manner by administering MOR(EtOH) (100 and 500 mg/kg) at 3, 4, and 5h after the carrageenan injection. The serum levels of tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) of MOR(EtOH)-treated mice were significantly reduced compared with those in the serum of animals administered carrageenan. Notably, MOR(EtOH) attenuated the expression of cyclo-oxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) and neutrophil infiltration in paw tissues injected with carrageenan. The anti-inflammatory mechanisms of MOR(EtOH) appear to be related to the inhibition of neutrophil infiltration, iNOS and COX-2 protein expression, NO release, and the decreasing TNF-alpha level in serum. The analytical results showed that the contents of berberine, palmatine and jatrorrhizine were 191.45 mg/g extract, 100.15 mg/g extract and 66.45 mg/g extract, respectively.

CONCLUSION

These experimental results suggest that MOR(EtOH) produced both analgesic and anti-inflammatory effects in mice and may be a candidate for the development of pharmacological agents used in the treatment of inflammatory disorders.

Biodistribution study and identification of inflammation sites using 99mTc-labelled stealth pH-sensitive liposomes

PURPOSE

To investigate the biodistribution and the ability of stealth pH-sensitive liposomes radiolabelled with 99mTc to identify inflammatory regions in a rat focal inflammation model.

METHODS

Preformed glutathione-containing stealth pH-sensitive liposomes were labelled with 99mTc-hexamethylpropylene amine oxime (99mTc-HMPAO). The 99mTc-HMPAO radiolabelled stealth pH-sensitive liposomes (99mTc-SpHL) were administered intravenously in Wistar male rats with inflammation induced by injection subplantar of carrageenan in the right foot. At pre-established time intervals the animals were anaesthetized and tissues were removed and analysed for 99mTc content using an automatic scintillation apparatus. Scintigraphic imaging was also performed after 2, 4 and 8 h of intravenous injection of 99mTc-SpHL.

RESULTS

The 99mTc-SpHL was significantly taken up by the spleen (19.21+/-2.98%ID/g at 30 min post-injection). Low radioactivity levels were found in the liver, lungs, and kidney. Moreover, the 99mTc-SpHL uptake was significantly higher in the inflamed foot when compared to the respective control (0.386+/-0.059 and 0.215+/-0.018%ID/g at 2 h post-injection, respectively). As early as 30 min after administration of 99mTc-SpHL, the focus of inflammation could be visualized scintigraphically. The value of the inflammatory and non-inflammatory site radioactivity counting ratio was greater than 5.

CONCLUSION

This result indicates that the 99mTc-SpHL presents a high tropism for inflammatory regions and may be useful as a radiopharmaceutical to identify these foci.

Low-intensity pulsed ultrasound and nonsteroidal anti-inflammatory drugs have opposing effects during stress fracture repair

Low-intensity pulsed ultrasound (LIPUS) and nonsteroidal anti-inflammatory drugs (NSAIDs) were used to treat stress fracture. Bilateral stress fractures were induced in the ulnas of 48 adult rats. Animals were divided into two groups (NSAID and VEH), and treated 5 days per week with celecoxib (5 mg/kg) mixed in a vehicle solution of polyethylene glycol and saline (NSAID) or vehicle alone (VEH). One-to-three hours following drug administration, all animals were treated with unilateral active-LIPUS and contralateral inactive-LIPUS. Equal numbers of ulnas from each drug group were histologically evaluated at 2, 4, and 8 weeks following induction of stress fracture. Neither LIPUS nor NSAID influenced bone resorption, but each had significant and opposite effects on intracortical bone formation rate. These effects indicate that LIPUS may be used to facilitate stress fracture repair whereas NSAID may delay tissue level repair of stress fractures. There was no interaction between LIPUS and NSAID, indicating that the beneficial LIPUS effect was not mediated by the cyclooxygenase-2 pathway. LIPUS accelerated stress fracture healing, whereas the NSAID delayed repair. When used in combination, the beneficial LIPUS effect was not impaired by the detrimental NSAID effect.

Anti-inflammatory and anti-nociceptive activities of methanolic extract of the leaves of Fraxinus floribunda Wallich

Fraxinus floribunda Wallich (Family-Oleaceae) is a wide green tree in the sub-alpine region of Sikkim, India. The methanolic extract of the leaves of Fraxinus floribunda (MEFF) at 100, 200 and 400 mg/kg/p.o was screened in rats for anti-inflammatory activity by acute-carrageenan induced paw edema, sub-acute cotton pellet induced granuloma and chronic Freund's adjuvant induced arthritis models. In all the three models of anti- inflammatory studies 200 and 400 mg/kg/p.o doses of the extract showed significant effect (P<0.001). Antinociceptive evaluation was performed by writhing and tail-immersion tests in mice. Anti-nociceptive evaluation revealed that MEFF at the dose of 400 mg/kg/p.o had significant activity against the control. The relieving effect was through the peripheral and central mechanism of action of the extract. This study rationalized the ethno medicinal use of the plant for relieving pain in inflammatory pathological conditions like fracture and dislocation.

Frequencies of single nucleotide polymorphisms in genes regulating inflammatory responses in a community-based population

BACKGROUND

Allele frequencies reported from public databases or articles are mostly based on small sample sizes. Differences in genotype frequencies by age, race and sex have implications for studies designed to examine genetic susceptibility to disease. In a community-based cohort of 9,960 individuals, we compared the allele frequencies of 49 single nucleotide polymorphisms (SNPs) of genes involved in inflammatory pathways to the frequencies reported on public databases, and examined the genotypes frequencies by age and sex. The genes in which SNPs were analyzed include CCR2, CCR5, COX1, COX2, CRP, CSF1, CSF2, IFNG, IL1A, IL1B, IL2, IL4, IL6, IL8, IL10, IL13, IL18, LTA, MPO, NOS2A, NOS3, PPARD, PPARG, PPARGC1 and TNF.

RESULTS

Mean(SD) age was 53.2(15.5); 98% were Caucasians and 62% were women. Only 1 out of 33 SNPs differed from the SNP500Cancer database in allele frequency by >10% in Caucasians (n = 9,831), whereas 12 SNPs differed by >10% (up to 50%) in African Americans (n = 105). Two out of 15 SNPs differed from the dbSNP database in allele frequencies by >10% in Caucasians, and 5 out of 15 SNPs differed by >10% in African Americans. Age was similar across most genotype groups. Genotype frequencies did not differ by sex except for TNF(rs1799724), IL2(rs2069762), IL10(rs1800890), PPARG(rs1801282), and CRP(rs1800947) with differences of less than 4%.

CONCLUSION

When estimating the size of samples needed for a study, particularly if a reference sample is used, one should take into consideration the size and ethnicity of the reference sample. Larger sample size is needed for public databases that report allele frequencies in non-Caucasian populations.

A new hat for an old enzyme: Waste management

The history of research regarding secretory phospholipase A(2) (sPLA(2)) has often focused in one of two directions. Originally, the enzyme was studied biophysically in terms of its fundamental structure, enzymology, and the relationship between membrane physics and catalytic activity. More recently, a large and growing body of information has accumulated concerning regulatory factors, tissue distribution, and physiological/pathological roles of sPLA(2). Evidence is presented that suggests an additional function for the protein in which it helps to clear dead and damaged cells while avoiding digestion of those that are healthy. Apparently, the ability of the enzyme to discriminate between susceptible and resistant cells depends on physical properties of membrane lipids related to order, distribution, and neighbor/neighbor interactions. Investigations into this action of the enzyme offer the rare opportunity to apply biophysical approaches and principles to a physiological setting.

Role of T cells, cytokines and antibody in dengue fever and dengue haemorrhagic fever

Dengue infections are a major cause of morbidity and mortality in the tropical and sub-tropical regions of the world. There is no vaccine for dengue and also there are no anti-viral drugs to treat the infection. Some patients, typically those experiencing a secondary infection with a different dengue serotype, may progress from an acute febrile disease to the more severe forms of disease, dengue haemorrhagic fever and dengue shock syndrome. Here we discuss the significant immunopathological component to severe disease and how T cells, cytokines and cross-reactive antibody combine to contribute to the progression to dengue haemorrhagic fever. These events are thought to lead to vascular leakage, the signature event in dengue haemorrhagic fever, and are addressed in this review by incorporating the concept of heterologous T cell immunity. The need for effective measures against dengue and dengue-related illness is clear. We propose that drugs against dengue virus, or the symptoms of severe dengue disease, are a viable goal.

Low-intensity pulsed ultrasound accelerates and a nonsteroidal anti-inflammatory drug delays knee ligament healing

BACKGROUND

Low-intensity pulsed ultrasound and nonsteroidal anti-inflammatory drugs are used to treat ligament injuries; however, their individual and combined effects are not established.

HYPOTHESES

Low-intensity pulsed ultrasound accelerates ligament healing, a nonsteroidal anti-inflammatory drug delays healing, and the nonsteroidal anti-inflammatory drug inhibits the beneficial effect of low-intensity pulsed ultrasound.

STUDY DESIGN

Controlled laboratory study.

METHODS

Sixty adult rats underwent bilateral transection of their knee medial collateral ligaments. Animals were divided into 2 drug groups and treated 5 d/wk with celecoxib (5 mg/kg) mixed in a vehicle solution (NSAID group) or vehicle alone (VEH group). One to 3 hours after drug administration, all animals were treated with unilateral active low-intensity pulsed ultrasound and contralateral inactive low-intensity pulsed ultrasound. Equal numbers of animals from each drug group were mechanically tested at 2 weeks (n = 14/group), 4 weeks (n = 8/group), and 12 weeks (n = 8/group) after injury.

RESULTS

Ultrasound and drug intervention did not interact to influence ligament mechanical properties at any time point. After 2 weeks of intervention, ligaments treated with active low-intensity pulsed ultrasound were 34.2% stronger, 27.0% stiffer, and could absorb 54.4% more energy before failure than could ligaments treated with inactive low-intensity pulsed ultrasound, whereas ligaments from the NSAID group could absorb 33.3% less energy than could ligaments from the VEH group. There were no ultrasound or drug effects after 4 and 12 weeks of intervention.

CONCLUSIONS

Low-intensity pulsed ultrasound accelerated but did not improve ligament healing, whereas the nonsteroidal anti-inflammatory drug delayed but did not impair healing. When used in combination, the beneficial low-intensity pulsed ultrasound effect was cancelled by the detrimental nonsteroidal anti-inflammatory drug effect.

CLINICAL RELEVANCE

Low-intensity pulsed ultrasound after ligament injury may facilitate earlier return to activity, whereas non-steroidal anti-inflammatory drugs may elevate early reinjury risk.

The metabolic coupling of arginine metabolism to nitric oxide generation by astrocytes

Arginine, the only known precursor of nitric oxide, enters the brain parenchyma from the blood through the endothelial cells or from the cerebral spinal fluid through the ependymal cells. Astrocytes, whose processes abut the endothelium and ependymum, take up arginine through cationic amino acid transporters and release arginine through this transport system to the synapses that astrocytes shield. Some of these synapses are excitatory, and liberate glutamate into the synaptic cleft. Glutamate induces arginine release from astrocytes, making it available to the neuron. Neurons can take up arginine to be used in nitric oxide-mediated processes, such as neurotransmission. Thus, neural and nonneural cells act in concert to affect neuron physiology in an elegantly integrated system. This review focuses on the components of the interaction between astrocytes and neurons in nitric oxide biology.

Effects of three purgative decoctions on inflammatory mediators

In traditional Chinese medicine (TCM), there are three Cheng-Chi-Tang decoctions (CCTDs) including: Ta-Cheng-Chi-Tang (TCCT), Xiao-Chen-Chi-Tang (XCCT) and Tiao-Wei-Chen-Chi-Tang (TWCCT), which are the frequently used purgative remedies to treat "internal heat"-induced symptoms like a bloated and painful abdomen, hard stools and fever, etc. Constituents in each formulation are Rheum palmatum L. (Polygonaceae), Magnolia officinalis Rehd. et Wils. (Magnoliaceae), Citrus aurantium L. (Rutaceae), Mirabilitum (mirabilite, crystals of sodium sulfate, Na2SO4) for TCCT; Rheum palmatum, Magnolia officinalis, Citrus aurantium for XCCT; and Rheum palmatum, Mirabilitum, Glycyrrhiza uralensis Fisch. (Leguminosae) for TWCCT. However, the underlying mechanisms for purging internal pathological heat are far from fully clarified, and few scientific investigations have been carried out to delineate the relationships between the anti-inflammatory effects and laxative potencies of these formulations. In this study, the anti-inflammatory effects of the three CCTDs on lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin E (PGE2) production in RAW 264.7 cells, carrageenan-induced paw edema in mice and the laxative effect in mice were explored. The results showed that TCCT inhibited LPS-induced NO and PGE2 production and inducible nitric oxide synthase (iNOS) expression in RAW 264.7 cells more effectively than did XCCT or TWCCT. Moreover, paw edema of carrageenan-treated mice was significantly attenuated in mice pretreated with 1 g/kg TCCT. TCCT also showed the strongest purgative activity among the three formulations. These findings indicate that TCCT has anti-inflammatory effects in addition to its traditionally known purgative activities. It may have potential to treat inflammatory disease conditions.

In Search of Secreted Protein Biomarkers for the Anti-inflammatory Effect of β2-Adrenergic Receptor Agonists: Application of DIGE Technology in Combination with Multivariate and Univariate Data Analysis Tools

Two-dimensional difference gel electrophoresis (DIGE) in combination with univariate (Student's t-test) and multivariate data analysis, principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to study the anti-inflammatory effects of the beta(2)-adrenergic receptor (beta(2)-AR) agonist zilpaterol. U937 macrophages were exposed to the endotoxin lipopolysaccharide (LPS) to induce an inflammatory reaction, which was inhibited by the addition of zilpaterol (LZ). This inhibition was counteracted by addition of the beta(2)-AR antagonist propranolol (LZP). The extracellular proteome of the U937 cells induced by the three treatments were examined by DIGE. PCA was used as an explorative tool to investigate the clustering of the proteome dataset. Using this tool, the dataset obtained from cells treated with LPS and LZP were separated from those obtained from LZ treated cells. PLS-DA, a multivariate data analysis tool that also takes correlations between protein spots and class assignment into account, correctly classified the different extracellular proteomes and showed that many proteins were differentially expressed between the proteome of inflamed cells (LPS and LZP) and cells in which the inflammatory response was inhibited (LZ). The Student's t-test revealed 8 potential protein biomarkers, each of which was expressed at a similar level in the LPS and LZP treated cells, but differently expressed in the LZ treated cells. Two of the identified proteins, macrophage inflammatory protein-1beta (MIP-1beta) and macrophage inflammatory protein-1alpha (MIP-1alpha) are known secreted proteins. The inhibition of MIP-1beta by zilpaterol and the involvement of the beta(2)-AR and cAMP were confirmed using a specific immunoassay.

Ageing affects nitric oxide synthase, cyclooxygenase and oxidative stress enzymes expression differently in mesenteric resistance arteries

1 Our aim was to study the role of nitric oxide (NO) and arachidonic acid pathways in the alpha(1)-adrenoceptor-mediated vasoconstriction in mesenteric resistance arteries from 3--4 and 22 to 23-month-old Sprague-Dawley rats. 2 The expression of NO synthase (NOS), cyclooxygenase (COX) isoforms, soluble guanylate cyclase, superoxide dismutase and the NAD(P)H oxidase subunits p22(phox) and p 47(phox) were determined. 3 The N(G)-nitro-l-arginine methyl ester, a non-selective NOS inhibitor, shifted to the left but indomethacin and NS 398, non-selective and selective COX-2 inhibitors, shifted to the right the concentration-response curve for the vasoconstriction by phenylephrine in both age groups. 4 Ageing up-regulated endothelial NOS and p22(phox) expression but did not modify COX, soluble guanylate cyclase, superoxide dismutase and p 47(phox) expression. 5 These data suggest that the observed enhancement of eNOS protein expression could constitute a compensatory mechanism to counter-regulate a chronic loss of NO possibly through increased superoxide anion production from NAD(P)H oxidase induced by age.

Protective effect of Radix Acanthopanacis Senticosi capsule on colon of rat depression model

AIM: To investigate the abnormity of rat colon caused by depression and the ameliorative effects of Radix Acanthopanacis Senticosi (RAS) capsule on colon and their mechanisms in rat depression model.

METHODS: Chronic stress-induced model of depression of Wistar rats was produced. The experimental animals were randomly divided into model control, 5-aminosalicylic acid (5-ASA) therapy group and three RAS capsule therapy groups. These five groups were intracolonically treated daily (8:00 a.m.) for 2 wk with normal saline, 5-ASA (100 mg/kg) and RAS capsule at the doses of 300, 600 and 900 mg/kg, respectively. A normal control group of rats was also included in the study. Colonic activities of nitric oxide (NO) and superoxide dismutase (SOD), levels of malondialdehyde (MDA) and inducible nitric oxide synthase (iNOS) were determined by ultraviolet spectrophotometry. The expression of cyclooxygenase-2 (COX-2) in colonic tissue was detected by immunohistochemistry.

RESULTS: Enhanced colon inflammatory response and oxidative stress were observed in the chronic stress-induced rat depression model, which manifested as the significant increase of MDA, iNOS and NO levels, as well as the expressions of COX-2 in the colon tissue, but the colonic SOD activity was significantly decreased compared with the normal control (MDA: 10.34±2.77 vs 2.55±0.70; iNOS: 1.11±0.44 vs 0.25±0.16; COX-2: 53.26±8.16 vs 4.87±1.65; NO: 11.28±5.66 vs 4.76±1.55; SOD: 53.39±11.15 vs 84.45±22.31; P<0.01). However, these parameters were significantly ameliorated in rats treated locally with RAS capsule at the doses of 300, 600 and 900 mg/kg (iNOS: 0.65±0.31, 0.58±0.22 and 0.64±0.33; NO: 5.99±2.73, 6.87±1.96 and 6.50±1.58; MDA: 2.92±0.75, 3.19±1.08 and 3.26±1.24; SOD: 70.81±12.36, 73.30±15.30 and 69.09±11.03, respectively). The expressions of COX-2 in the colon were significantly ameliorated (28.83±9.48 and 27.04±9.56, respectively) when RAS capsule was administered at the doses of 600 and 900 mg/kg.

CONCLUSION: Administration of RAS capsule intracolonically may have significant therapeutic effects on the colon of rat depression model, which are probably due to its antioxidative action and inhibition of arachidonic acid metabolism.

Cyclo-Oxygenase-2 Inhibitors

The major goal of clinicians when treating acute musculoskeletal injuries is to return athletes to their pre-injury level of function, ideally in the shortest time possible and without compromising tissue-level healing. In this regard, a commonly used intervention is the taking of NSAIDs. These are used to limit the amount and duration of inflammation, and to control pain. While NSAIDs have become synonymous with the management of acute musculoskeletal injuries, their efficacy has yet to be proven. This is of particular concern in view of recent research investigating the latest class of NSAIDs - selective cyclo-oxygenase-2 inhibitors (COXIBs). COXIBs were developed to reduce the adverse gastrointestinal (GI) effects of traditional NSAIDs. While they have beneficial anti-inflammatory and analgesic properties, and appear to facilitate earlier return to function following acute injury, the effect of COXIBs on tissue-level healing is currently unknown. In experimental animal models of acute injury, COXIBs have been shown to be detrimental to tissue-level repair. Specifically, they have been shown to impair mechanical strength return following acute injury to bone, ligament and tendon. Clinically, this may have implications for ongoing morbidity and future injury susceptibility. However, the current animal studies have limited translation to the clinical setting, particularly because of significant limitations relating to drug use and dosage in these studies. There is currently no randomised, controlled trial evidence of the tissue-level effects of COXIBs on acute musculoskeletal injuries. In addition to questions relating to the effect of COXIBs on tissue-level healing, further questions regarding the use of these agents have been raised given a recent link being shown between one COXIB (rofecoxib) and an increased risk for adverse cardiovascular events. Whether this finding is related to the individual properties of rofecoxib or is a class phenomenon is the subject of ongoing investigation. However, in light of the potential risks associated with using COXIBs, an acceptable and possibly safer alternative in the management of acute musculoskeletal injuries may be to use traditional NSAIDs. Traditional NSAIDs do carry the potential for greater adverse GI effects and their clinical effects on tissue-level healing remain relatively unknown. However, they do not appear to be associated with adverse cardiovascular effects, and they are effective pain relievers and cheaper alternatives.

Effects of different protocol doses of low power gallium–aluminum–arsenate (Ga–Al–As) laser radiation (650 nm) on carrageenan induced rat paw ooedema

The purpose of the present study was to investigate the effect of the low power laser therapy on the acute inflammatory process. Male Wistar rats were used. The rat paw oedema was induced by sub-plantar injection of carrageenan, the paw volume was measured before and 1, 2, 3 and 4 h after the injection using a hydroplethysmometer. To investigate the mechanism action of the Ga-Al-As laser on inflammatory oedema, parallel studies were performed using adrenallectomized rats or rats treated with sodium diclofenac. Different laser irradiation protocols were employed for specific energy densities (EDs), exposure times and repetition rates. The rats were irradiated with the Ga-Al-As laser during 80 s each hour. The ED that produced an anti-inflammatory effect were 1 and 2.5 J/cm(2), reducing the oedema by 27% (P<0.05) and 45.4% (P<0.01), respectively. The ED of 2.5 J/cm(2) produced anti-inflammatory effects similar to those produced by the cyclooxigenase inhibitor sodium diclofenac at a dose of 1 mg/kg. In adrenalectomized animals, the laser irradiation failed to inhibit the oedema. Our results suggest that low power laser irradiation possibly exerts its anti-inflammatory effects by stimulating the release of adrenal corticosteroid hormones.

Mechanism of anti-nociceptive effects of Asarum sieboldii Miq. radix: potential role of bradykinin, histamine and opioid receptor-mediated pathways

The radix of Asarum sieboldii Miq. (AR) has been used to treat pain and inflammation in Korea. The present study was conducted to gain insights into the mechanism of actions regarding anti-nociceptive and anti-inflammatory activities of AR. Administration of methanol extract of AR caused dramatic anti-nociceptive effects based on acetic acid writhing and tail-flick assay. When naloxone (Nx) was pre-treated, AR extract failed to exert such anti-nociceptive effect in the tail-flick assays. These results suggest that AR extract have opioid-like activity. It also exerted significant anti-inflammatory effects in the rat paw edema assay. AR extract caused inhibition in the bradykinin (BK)/histamine-mediated ileum contractions of guinea pig. Taken together, these results provide evidence that the methanol extract of AR exerts anti-nociceptive and anti-inflammatory effects by activating opioid receptor as well as by inhibiting bradykinin and histamine-mediated actions.

A continuous spectrophotometric assay for phospholipase A(2) activity

This paper describes a simple continuous spectrophotometric method for assaying phospholipase A(2) (PLA(2)) activity. The procedure is based on a coupled enzymatic assay, using dilinoleoyl phosphatidylcholine as phospholipase substrate and lipoxygenase as coupling enzyme. The linoleic acid released by phospholipase was oxidized by lipoxygenase and then phospholipase activity was followed spectrophotometrically by measuring the increase in absorbance at 234 nm due to the formation of the corresponding hydroperoxide from the linoleic acid. The optimal assay concentrations of hog pancreatic phospholipase A(2) and lipoxygenase were established. PLA(2) activity varied with pH, reaching its optimal value at pH 8.5. Scans of the deoxycholate concentration pointed to an optimal detergent concentration of 3mM. Phospholipid hydrolysis followed classical Michaelis-Menten kinetics (V(m)=1.8 microM/min, K(m)=4.5 microM, V(m)/K(m)=0.4 min(-1)). This assay also allows PLA(2) inhibitors, such as p-bromophenacyl bromide or dehydroabietylamine acetate, to be studied. This method was proved to be specific since there was no activity in the absence of phospholipase A(2). It also has the advantages of a short analysis time and the use of commercially nonradiolabeled and inexpensive substrates, which are, furthermore, natural substrates of phospholipase A(2).

The Potential Contributions of Chronic Inflammation to Lung Carcinogenesis

A number of lines of evidence suggests that chronic inflammation contributes to the process of carcinogenesis. In this article, this theme is explored with particular emphasis on the involvement of inflammation in the development of lung cancer. A number of molecular pathways activated in chronic inflammation may contribute to lung carcinogenesis. The challenge is to conceptualize a cohesive picture of this complex biology that allows for effective pharmaceutical intervention. Initial therapeutic efforts involve strategies to block single pathways, such as with cyclooxygenase (COX) activity. However, the more that is learned about the consequences of COX activity, the more evident are the relationships of this enzyme to other classes of regulatory molecules such as the potent nuclear factor-kB. In light of this emerging picture, more global intervention strategies, such as with drug combinations, may be essential for success. Further basic study is essential to sort out possible molecular relationships and to permit elucidation of the most critical regulatory circuits. Given the complexity of these molecular interactions, well-designed clinical trials that specifically evaluate the precise effects of particular antiinflammatory drugs on lung carcinogenesis will also be critical to sort out the complexity and to validate successful approaches to arresting lung carcinogenesis.

Ketamine/xylazine attenuates LPS-induced iNOS expression in various rat tissues

Ketamine and xylazine (K/X) are commonly used in combination as an anesthetic agent in experimental animal models. We previously noted that K/X attenuated lipopolysaccharide (LPS)-induced liver injury, gastric stasis, and reduced symptoms of endotoxemia. Because ketamine attenuates expression of several proinflammatory genes, we examined the effects of K/X on inducible nitric oxide synthase (iNOS), which has been implicated in endotoxin-induced tissue injury. We hypothesized that K/X would attenuate LPS-induced expression of iNOS in various organs in the rat. Rats were given either intraperitoneal saline or ketamine (70 mg/kg) and xylazine (6 mg/kg) 1 h before saline or LPS (20 mg/kg). Rats were sacrificed 5 h later and stomach, duodenum, jejunum, ileum, colon, liver, lung, kidney, and spleen were collected for determination of iNOS protein immunoreactivity by Western immunoblot. Data reported in densitometric units (DU) as mean +/- SEM (n >/= 5; ANOVA). LPS significantly increased iNOS protein immunoreactivity in all tissues examined versus saline controls (P </= 0.05, all groups). K/X significantly attenuated LPS-induced iNOS protein immunoreactivity in all of the aforementioned organs (P </= 0.05, all groups). Furthermore, K/X almost completely blunted LPS-induced expression of iNOS in stomach, duodenum, jejunum, and colon. These data indicate that K/X attenuates LPS-induced upregulation of iNOS in a variety of tissues. Furthermore, in rat models studying the in vivo effects of endotoxin, especially those evaluating the gastrointestinal system, careful consideration needs to be given if the anesthetic combination of K/X is used, as it alters LPS-induced expression of iNOS, an important pathophysiologic mediator in endotoxemia.

Vascular permeabilization by intravenous arachidonate in the rat peritoneal cavity: antagonism by antioxidants

Arachidonic acid was investigated for its vascular permeabilizing potential in the rat peritoneal cavity and for its mechanism of action. The antagonistic potential of antioxidants (vitamin E, vitamin C and troxerutin) was also evaluated. Vascular permeability was equated to the rate of extravasation of Evans blue dye from plasma into the peritoneal cavity. Baseline permeability was linear up to 2 h, with a rate constant (k) of 0.0031+/-0.0007 h(-1). Intravenous arachidonate (from 30 microg/kg to 3 mg/kg) induced an immediate, dose-related and significant increase in permeability (ranging from 80% to 150%), which was comparable to the effect induced by similar doses of serotonin. Aspirin (10 mg/kg) reduced the arachidonate-induced permeability by 75%, but interestingly neither the stable thromboxane A(2) receptor agonist U46619 (prostaglandin H(2) endoperoxide epoxymethane) nor prostacyclin was able to increase peritoneal vascular permeability. In contrast, the permeabilizing action of arachidonic acid was very sensitive to antioxidant agents. Thus, vitamin C and the flavonoid compound troxerutin (100 mg/kg) fully abolished arachidonate-induced permeability, whereas vitamin E had only a partial effect (40-100% inhibition). In conclusion, intravenous administration of arachidonic acid strongly enhanced peritoneal vascular permeability in the rat, apparently via free radical generation. This rat peritoneal model can be used to evaluate the in vivo antinflammatory potential of antioxidant drugs.

Endogenous versus exogenous glucocorticoid responses to experimental bacterial sepsis

Although lack of adrenals dramatically reduces resistance against sepsis generally, the value of glucocorticoid levels above those normally produced by stress remains controversial. An early and long-held concept is that glucocorticoid protection against lipopolysaccharides in animal models is important. Supporting this concept, C3H/HeJ mice, lacking Toll-like receptor-4 (TLR-4), and consequently, endotoxin hyporesponsive, have recently been shown to be resistant to glucocorticoid protection against live Escherichia coli. Effective antibiotic intervention, as an additional parameter and with concomitant administration of glucocorticoid, not only allows for expected antibiotic protection but also for glucocorticoid protection against E. coli or Staphylococcus aureus of mice sensitized to tumor necrosis factor alpha, regardless of the status of the TLR-4 receptor. TLRs, including but not limited to TLR-2, may be involved in glucocorticoid protective efficacy against Gram-positive and Gram-negative sepsis. Overlapping and possibly endotoxin-independent signaling may become important considerations.

Severe hypoxia inhibits prostaglandin I(2) biosynthesis and vasodilatory responses induced by ionophore A23187 in the isolated rabbit ear

The present study was designed to test the hypothesis that lack of oxygen in severely hypoxic tissue may inhibit arachidonic acid oxygenation and thereby result in an inhibition of eicosanoid synthesis. Hypoxia was induced in the isolated rabbit ear, and arachidonate metabolism and peripheral resistance of the preparation were monitored simultaneously. Severe hypoxia completely inhibited the biosynthesis of prostaglandin I(2) induced by ionophore A23187 and converted the vasodilatory response observed under normoxia into vasoconstriction. The cyclooxygenase 1 inhibitor SC560 (1 micromol/l) effectively inhibited the normoxic prostaglandin I(2) biosynthesis, while the cyclooxygenase 2 inhibitor DFU (1 micromol/l) did not. Neither SC560 nor DFU affected normoxic vasodilatory responses, indicating no involvement of prostanoids. The nitric oxide (synthase inhibitor Nomega-nitro-L-arginine methyl ester (100 micromol/l) converted the vasodilation into vasoconstriction, similar to what was observed under hypoxia, suggesting that the hypoxia-mediated conversion might occur due to the inhibition of nitric oxide.

Hypertension alters the participation of contractile prostanoids and superoxide anions in lipopolysaccharide effects on small mesenteric arteries

The involvement of cyclooxygenase-2 (COX-2)-derived products and superoxide anion in the effect of lipopolysaccharide in noradrenaline (NA)-induced contraction was investigated in small mesenteric arteries (SMA) from normotensive, Wistar Kyoto (WKY), and spontaneously hypertensive (SHR) rats. In WKY, lipopolysaccharide (10 microg/ml, 1 and 5 h) only inhibited the NA response (0.1-30 microM) in the presence of dexamethasone (1 microM), indomethacin (10 microM), the selective COX-2 inhibitor, NS 398 (10 microM), and the TXA(2)/PGH(2) receptor antagonist, SQ 29,548 (10 microM) but not of superoxide dismutase (SOD, 100 U/ml). In SHR, lipopolysaccharide inhibited the NA response by itself; this inhibition was potentiated by dexamethasone, indomethacin, NS 398, SQ 29,548 and SOD. The effect of lipopolysaccharide plus indomethacin, NS 398 or SQ 29,548 was higher in SMA from WKY than SHR only after 1 h lipopolysaccharide incubation. N(G)-nitro-L-arginine methyl ester (100 microM) and endothelium removal abolished the indomethacin-induced potentiatory effect of lipopolysaccharide in both strains. Endothelium removal also abolished the SOD potentiatory effect in SMA from SHR. Lipopolysaccharide increases COX-2 expression to a similar level in both strains and iNOS expression in a greater extent in SHR; these increases were reduced by dexamethasone. These results indicate: 1) lipopolysaccharide induces the endothelial production of contractile prostanoids from COX-2 in SMA, probably to compensate the increase in NO from iNOS; 2) the production of prostanoids in the presence of lipopolysaccharide seems to be greater in normotensive than hypertensive rats only after lipopolysaccharide short incubation times; 3) endothelial production of O(2)(.-) contributes to counteract depression of NA contraction caused by lipopolysaccharide only in SHR.

Enhanced utilization and altered metabolism of arginine in inflammatory macrophages caused by raised nitric oxide synthesis

Nitric oxide (NO) production was increased in macrophages during inflammation. Casein-elicitation of rodents causing a peritoneal inflammation offered a good model to study alterations in the metabolism of L-arginine, the precursor of NO synthesis. The utilization of L-arginine for NO production, arginase pathway and protein synthesis were studied by radioactive labeling and chromatographic separation. The expression of NO synthase and arginase was studied by Western blotting.Rat macrophages utilized more arginine than mouse macrophages (228+/-27 versus 71+/-12.8pmol per 10(6) macrophages). Arginine incorporation into proteins was low in both species (<15% of labeling). When NO synthesis was blocked, arginine was utilized at a lower general rate, but L-ornithine formation did not increase. The expression of enzymes utilizing arginine increased. NO production was raised mainly in rats (1162+/-84pmol citrulline per 10(6) cells) while in mice both arginase and NO synthase were active in elicited macrophages (677+/-85pmol ornithine and 456+/-48pmol citrulline per 10(6) cells). We concluded, that inflammation induced enhanced L-arginine utilization in rodent macrophages. The expressions and the activities of arginase and NO synthase as well as NO formation were increased in elicited macrophages. Specific blocking of NO synthesis did not result in the enhanced effectivity of the arginase pathway, rather was manifested in a general lower rate of arginine utilization. Different rodent species reacted differently to inflammation: in rats, high NO increase was found exclusively, while in mice the activation of the arginase pathway was also important.

Role of an endoplasmic reticulum Ca(2+)-independent phospholipase A(2) in oxidant-induced renal cell death

Phospholipase A(2) (PLA(2)) hydrolyzes the sn-2 ester bond in phospholipids, releasing a fatty acid and a lysophospholipid. Recently, a novel 85-kDa membrane-bound-Ca(2+)-independent PLA(2) (iPLA(2)) was identified in insect and bacterial cells transfected with candidate PLA(2) sequences. However, few data exist demonstrating a membrane-bound-iPLA(2) in mammalian cells, its subcellular localization, or its physiological role. Herein, we demonstrate the expression of an 85-kDa endoplasmic reticulum (ER)-Ca(2+)-iPLA(2) (ER-iPLA(2)) in rabbit renal proximal tubule cells (RPTC) that is plasmalogen selective and is inhibited by the specific Ca(2+)-iPLA(2) inhibitor bromoenol lactone (BEL). RPTC exposed to tert-butylhydroperoxide for 24 h exhibited 20% oncosis compared with 2% in controls. Inhibition of ER-iPLA(2) with BEL before tert-butylhydroperoxide exposure resulted in 50% oncosis. To determine whether this effect was common to oxidants, we tested the ability of BEL to potentiate oncosis induced by cumene hydroperoxide, menadione, duraquinone, cisplatin, and the nonoxidant antimycin A. All oxidants tested produced oncosis after 24 h, and prior inhibition of ER-iPLA(2) potentiated oncosis at least twofold. In contrast, inhibition of ER-iPLA(2) did not alter antimycin A-induced oncosis. Lipid peroxidation increased from 1.4- to 5.2-fold in RPTC treated with BEL before oxidant exposure, whereas no change was seen in antimycin A-treated RPTC. These results are the first to demonstrate the expression and subcellular localization of an ER-iPLA(2). These results also suggest that ER-iPLA(2) functions to protect against oxidant-induced lipid peroxidation and oncosis.

Suppression of Japanese encephalitis virus infection by non-steroidal anti-inflammatory drugs

Japanese encephalitis virus (JEV) infection generates a rapid inflammatory response including peripheral neutrophil leucocytosis and infiltration of neutrophils into extraneural tissue. The level of inflammation correlates well with the clinical outcome in Japanese encephalitis patients. Non-steroidal anti-inflammatory drugs (NSAIDs), used medicinally for their analgesic and anti-inflammatory properties, are being considered for prevention of cardiovascular disease and cancer, as well as for treatment of human immunodeficiency virus infection. Apart from their ability to inhibit prostaglandin synthesis, the mechanisms underlying the beneficial therapeutic effects are largely unknown. We used aspirin, indomethacin and sodium salicylate to study the role of NSAIDs in JEV propagation in vitro. We found that NSAIDs suppressed JEV propagation in neuronal and non-neuronal cells. Blockade of cyclooxygenase activity by NSAIDs caused decreased production of free radicals and prostaglandins. However, these pharmacological alterations did not seem to correlate well with the antiviral effects. When cells were treated with the mitogen-activated protein kinase (MAPK) inhibitors PD 98059 and SB 203580, salicylate lost its antiviral effect. The activation of MAPK by anisomycin mimicked the action of salicylate in suppressing JEV-induced cytotoxicity. The decreased phosphorylation of extracellular signal-regulated kinase (ERK) was induced by JEV infection and the decrease in ERK was reversed by salicylate. Our data suggest that the signalling pathways of MAPK play a role in the antiviral action of salicylate.

Nitric oxide, interleukin and prostaglandin interactions affecting the magnocellular system

Magnocellular neurons are innervated by an excitatory histaminergic pathway. They also express neuronal NO synthase, interleukin-1beta (IL-1beta) and cyclo-oxygenase (COX). In normally hydrated rats when NO synthase activity is inhibited with N(G)-nitro-L-arginine methyl ester (L-NAME), administered intracerebroventricularly (i.c.v.), OT concentration in plasma increases. In the present study, the increase in hormone after L-NAME is attenuated by indomethacin, an inhibitor of COX, as well as by antagonists of histamine receptors at H1 (pyrilamine) and H2 (cimetidine) subtypes injected i.c.v. Moreover, enhanced OT secretion induced by centrally administered IL-1beta, but not naloxone (opiate receptor antagonist), is prevented by indomethacin. PGE2 and PGD2 (i.c.v.) stimulate OT release, but only PGD2 affects circulating vasopressin levels. Thus, NO inhibits release of OT stimulated by: (1) a COX-dependent mechanism, i.e. NO-->-(COX-->+PG-->+OT release); (2) histamine, i.e. NO-->-(histamine-->H1 and H2 receptors-->+OT release); and possibly (3) IL-1beta, i.e. NO-->-(IL-1beta-->+COX-->+PG-->+OT release). These interactions of NO, cytokine and histamine may be important for management of stress-induced activation of neuroendocrine systems.

Histamine production by Haemophilus somnus

Ten Haemophilus somnus isolates were grown on blood agar plates under a 5% CO2 atmosphere for 48 h. Harvested whole cells were washed and evaluated for the presence of histamine by ELISA. All H. somnus isolates had cell-associated histamine concentrations of between 18.5 and 200 ng/ml. In a separate study, the ability of H. somnus to secrete histamine into BHI growth medium was evaluated using H. somnus strains 8025 and 156A as well as a recent 156A respiratory isolate. Each strain or isolate was grown under various concentrations of CO2 to approximate the CO2 concentration in the bronchi. The histamine content of washed whole cells and medium supernatant were determined at various stages of incubation. Highest histamine concentrations were detected in the recent respiratory isolate; whole cells (225 ng/ml) after 120 h incubation in 15% CO2 and supernatant (1721 ng/ml) after incubation for 41 h in 25% CO2. This study indicates that different H. somnus isolates can produce and secrete histamine which may be enhanced by CO2 concentrations which approximate those in the bronchial tree. Results of this study may partially explain some of the post-vaccination reactions occasionally observed with H. somnus bacterins. Additional studies are needed to determine the actual role of H. somnus-derived histamine in the pathogenesis of bovine respiratory disease and airway hyperresponsiveness.

Enhancement of mast cell survival: a novel function of some secretory phospholipase A(2) isotypes

This study tested the hypothesis that certain secretory phospholipase A(2) (sPLA(2)) isotypes act in a cytokine-like fashion through cell surface receptors to influence mast cell survival. Initial experiments revealed that sPLA(2) activity and sPLA(2) receptor expression are increased, and mast cells lost their capacity to maintain membrane asymmetry upon cytokine depletion. Groups IB and III, but not group IIA PLA(2), prevented the loss of membrane asymmetry. Similarly, group IB prevented nucleosomal DNA fragmentation in mast cells. Providing putative products of sPLA(2) hydrolysis to cytokine-depleted mast cells did not influence survival. Furthermore, catalytic inactivation of sPLA(2) did not alter its capacity to prevent apoptosis. Inhibition of protein synthesis using cycloheximide or actinomycin reversed the antiapoptotic effect of sPLA(2). Additionally, both wild-type and catalytically inactive group IB PLA(2) induced IL-3 synthesis in mast cells. However, adding IL-3-neutralizing Ab did not change Annexin V(FITC) binding and only partially inhibited thymidine incorporation in sPLA(2)-supplemented mast cells. In contrast, IL-3-neutralizing Ab inhibited both Annexin V(FITC) binding and thymidine incorporation in mast cells maintained with IL-3. sPLA(2) enhanced phosphoinositide 3'-kinase activity, and a specific inhibitor of phosphoinositide 3'-kinase reversed the antiapoptotic effects of sPLA(2). Likewise, sPLA(2) increased the degradation of I-kappaBalpha, and specific inhibitors of nuclear factor kappa activation (NF-kappaB) reversed the antiapoptotic effects of sPLA(2). Together, these experiments reveal that certain isotypes of sPLA(2) enhance the survival of mast cells in a cytokine-like fashion by activating antiapoptotic signaling pathways independent of IL-3 and probably via sPLA(2) receptors rather than sPLA(2) catalytic products.

Inactivation of glutathione S-transferases by nitric oxide-derived oxidants: exploring a role for tyrosine nitration

Reactive intermediates derived from nitric oxide ((*)NO) are thought to play a contributing role in disease states associated with inflammation and infection. We show here that glutathione S-transferases (GSTs), principal enzymes responsible for detoxification of endogenous and exogenous electrophiles, are susceptible to inactivation by reactive nitrogen species (RNS). Treatment of isolated GSTs or rat liver homogenates with either peroxynitrite, the myeloperoxidase/hydrogen peroxide/nitrite system, or tetranitromethane, resulted in loss of GST activity with a concomitant increase in the formation of protein-associated 3-nitrotyrosine (NO(2)Tyr). This inactivation was only partially (<25%) reversible by dithiothreitol, and exposure of GSTs to hydrogen peroxide or S-nitrosoglutathione was only partially inhibitory (<25%) and did not result in protein nitration. Thus, irreversible modifications such as tyrosine nitration may have contributed to GST inactivation by RNS. Since all GSTs contain a critical, highly conserved, active-site tyrosine residue, we postulated that this Tyr residue might present a primary target for nitration by RNS, thus leading to enzyme inactivation. To directly investigate this possibility, we analyzed purified mouse liver GST-mu, following nitration by several RNS, by trypsin digestion, HPLC separation, and matrix-assisted laser desorption/ionization-time of flight analysis, to determine the degree of tyrosine nitration of individual Tyr residues. Indeed, nitration was found to occur preferentially on several tyrosine residues located in and around the GST active site. However, RNS concentrations that resulted in near complete GST inactivation only caused up to 25% nitration of even preferentially targeted tyrosine residues. Hence, nitration of active-site tyrosine residues may contribute to GST inactivation by RNS, but is unlikely to fully account for enzyme inactivation. Overall, our studies illustrate a potential mechanism by which RNS may promote (oxidative) injury by environmental pollutants in association with inflammation.

Stimulation of cyclooxygenase-2-activity by nitric oxide-derived species in rat chondrocyte: lack of contribution to loss of cartilage anabolism

Cross-talk between inducible nitric oxide synthase (NOS II) and cyclooxygenase-2 (COX-2) was investigated in rat chondrocytes. In monolayers, interleukin-1beta (IL-1beta) induced COX-2 and NOS II expression in a dose- and time-dependent manner, to produce high prostaglandin E(2) (PGE(2)) and nitrite (NO(2)(-)) levels in an apparently coordinated fashion. COX-2 mRNA was induced earlier (30 min. versus 4 hr) and less markedly (4-fold versus 12-fold at 24 hr) than NOS II, and was poorly affected by the translational inhibitor cycloheximide (CHX). IL-1beta did not stabilize COX-2 mRNA in contrast to CHX. Indomethacin and NS-398 lacked any effect on NO(2)(-) levels whereas L-NMMA and SMT reduced PGE(2) levels at concentration inhibiting NO(2)(-) production from 50 to 90%, even when added at a time allowing a complete expression of both enzymes (8 hr). Basal COX activity was unaffected by NO donors. The SOD mimetic, CuDips inhibited COX-2 activity by more than 75% whereas catalase did not. Inhibition of COX-2 by CuDips was not sensitive to catalase, consistent with a superoxide-mediated effect. In tridimensional culture, IL-1beta inhibited radiolabelled sodium sulphate incorporation while stimulating COX-2 and NOS II activities. Cartilage injury was corrected by L-NMMA or CuDips but not by NSAIDs, consistent with a peroxynitrite-mediated effect. These results show that in chondrocytes: (i) COX2 and NOS II genes are induced sequentially and distinctly by IL-1beta; (ii) COX-1 and COX-2 activity are affected differently by NO-derived species; (iii) peroxynitrite accounts likely for stimulation of COX-2 activity and inhibition of proteoglycan synthesis induced by IL-1beta.