Endothelins modulate inflammatory reaction in zymosan-induced arthritis: participation of LTB4, TNF-alpha, and CXCL-1

The Anti-Arthritic Potential of the Ethanolic Extract of Salvia Lachnostachys Benth. Leaves and Icetexane Dinor-Diterpenoid Fruticuline B

The decoction of Salvia lachnostachys Benth. leaves is used in Brazilian folk medicine for anti-spasmodic, antipyretic, and anxiolytic purposes. Some of the biological effects of an S. lachnostachys extract have been shown to be anti-inflammatory, anti-cancer, and antidepressant effects. In addition, this medicinal plant produces several compounds including icetexane diterpenoids, such as fruticuline A and fruticuline B. The aim of the present work was to evaluate the anti-hyperalgesic and anti-inflammatory properties of fruticuline B (FRUT B) and the ethanolic extract obtained from the leaves of S. lachnostachys (EESL) in experimental mouse models. EESL (30, 100, and 300 mg/kg) and FRUT B (1 mg/kg) were evaluated in articular inflammation-induced models in Swiss mice. In articular inflammation induced by Zymosan, EESL (300 mg/kg) and FRUT B (1 mg/kg) significantly reduced mechanical hyperalgesia (83.17% inhibition for EESL and 81.19% for FRUT B); edema (68.75% reduction for EESL and 33.66% for FRUT B); leukocyte migration (81.3% for EESSL and 92.2% for FRUT B), and nitric oxide production (88.3% for EESL and 74.4% for FRUT B). The exposure to fruticuline B significantly inhibited the edema (51.5%), mechanical (88.12%) and cold hyperalgesia (80.8%), and myeloperoxidase (MPO) (63.4%) activity 24 h after CFA injection. In the pleurisy model, FRUT B reduced 89.1% of leukocyte migration and 50.3% in nitric oxide production. Four hours after carrageenan injection, FRUT B (1 mg/kg) diminished 89.11% of mechanical hyperalgesia, 65.8% of paw edema, and 82.12% of the response to cold hyperalgesia. In the MTT test, EESL and fruticuline B caused no cytotoxicity. The present study revealed, for the first time, the anti-arthritic and anti-nociceptive effects of FRUT B, pointing out the therapeutic potential of the species to control inflammation and nociception. Future studies are needed to evaluate other biological properties of fruticuline B and to better understand its mechanism of action.

Chemokine Regulation in Temporomandibular Joint Disease: A Comprehensive Review

Temporomandibular joint disorders (TMDs) are conditions that affect the muscles of mastication and joints that connect the mandible to the base of the skull. Although TMJ disorders are associated with symptoms, the causes are not well proven. Chemokines play an important role in the pathogenesis of TMJ disease by promoting chemotaxis inflammatory cells to destroy the joint synovium, cartilage, subchondral bone, and other structures. Therefore, enhancing our understanding of chemokines is critical for developing appropriate treatment of TMJ. In this review, we discuss chemokines including MCP-1, MIP-1α, MIP-3a, RANTES, IL-8, SDF-1, and fractalkine that are known to be involved in TMJ diseases. In addition, we present novel findings that CCL2 is involved in β-catenin-mediated TMJ osteoarthritis (OA) and potential molecular targets for the development of effective therapies. The effects of common inflammatory factors, IL-1β and TNF-α, on chemotaxis are also described. In conclusion, this review aims to provide a theoretical basis for future chemokine-targeted therapies for TMJ OA.

Analgesic and Anti-Inflammatory Properties of Ethanolic Extract of Piper vicosanum Leaves

Nonclinical trials are important to validate the efficacy and safety of medicinal plants. Scientific toxicological studies with Piper vicosanum Yuncker have showed its safety; however, no studies have indicated the analgesic or antiarthritic potential of the ethanolic extract of P. vicosanum leaves (EEPV). The objective of the present work was to evaluate the antiarthritic and antinociceptive effects of EEPV in experimental mouse models. The oral administration of EEPV (100, 300, and 700 mg/kg) and dexamethasone (1 mg/kg) were performed in carrageenan-induced pleurisy, in formalin and acetic-acid-induced nociception, and in zymosan-induced articular inflammation models in Swiss mice. The EEPV (300 mg/kg) was tested in zymosan-articular inflammation, the complete Freund's adjuvant (CFA) inflammatory model, and in in situ intravitreal microscopy analysis of rolling and adhesion events of leukocytes in the mesenteric microcirculation in mice. EEPV significantly inhibited: (i) nociceptive response at phase 1 and 2, and also in the cold response in the formalin model; (ii) abdominal contortion induced by acetic acid; (iii) mechanical hyperalgesia after 4 and 6 h, knee edema after 6 h, and leukocyte migration in articular inflammation induced by zymosan. All doses of EEPV reduced the leukocyte migration to the inflamed pleural cavity and knee edema 4 h after the zymosan knee injection. The treatment with the EEPV significantly inhibited the CFA-induced edema, mechanical and cold hyperalgesia, and NAG and MPO. The EEPV also significantly inhibited carrageenan-induced leukocyte rolling and adhesion. The present study revealed, for the first time, the antiarthritic and antinociceptive effects of the EEPV.

Exploring the pivotal role of endothelin in rheumatoid arthritis

A chronic inflammatory disorder, rheumatoid arthritis (RA) is an autoimmune and systemic disease characterized by progressive and prolonged destruction of joints. This results in increased mortality, physical disability and destruction. Cardiovascular disorders are one of the primary causes of mortality in patients with RA. It is multifactorial in nature and includes genetic, environmental and demographic factors which contribute to the severity of disease. Endothelin-1 (ET-1) is a peptide which acts as a potent vasoconstrictor and is generated through vascular smooth muscle and endothelial cells. Endothelins may be responsible for RA, as under certain circumstances they produce reactive oxygen species which further promote the production of pro-inflammatory cytokines. This enhances the production of superoxide anion, which activates pro-inflammatory cytokines, resulting in RA. The aim of this review is to elucidate the role of endothelin in the progression of RA. This review also summarizes the natural and synthetic anti-inflammatory drugs which have provided remarkable insights in targeting endothelin.

Analysis of hematological parameters in rheumatoid arthritis patients receiving biological therapy: contribution to prevention of avoidable hematological complications

Administration of biological therapy (BT) in rheumatoid arthritis (RA) patients is often associated with hematological complications, which result in switching among therapies. Thus, there is an instant need for suitable screening parameters that will help to individualize the therapy and minimize the onset of adverse effects. We analyzed the hematological profile of 99 RA patients receiving TNFα (Adalimumab - ADA, Golimumab - GOL, Etanercept - ETA) or IL-6 receptor (Tocilizumab - TCZ) inhibitors in order to find possible indicators to improve personalization of RA therapy. BTs significantly affect the levels of observed hematological parameters. In contrast to TNF-α inhibitors, TCZ normalized almost all monitored hematological parameters to values of healthy donors. Only GOL from the TNF-α inhibitors studied, was able to normalize neutrophil counts, as well as platelet indicators. Importantly, effects on the blood parameters (e.g. lymphocytes or platelet count) differ even within the same therapeutic group (anti-TNFα). Variable effects of individual biological agents in RA treatment point to importance to evaluate the patient's hematological profile to improve the selection of suitable BT. It will help to personalize the administration of BT and prevent unnecessary switching from an effective therapy just because of provocation of avoidable hematological complications.

Nanoparticle conjugated with aptamer anti-MUC1/Y for inflammatory arthritis

Aptamers may form well-defined three-dimensional structures binding with high affinity and stability to a specific receptor. The aptamer anti-MUC1 isoform Y is one the most used due the affinity to MUC1, which is overexpressed in several types of cancer and inflammation process. In this study we have developed, characterized, in vitro as in vivo evaluated a nanoaptamer (anti-MUC1/Y) as a nanoagent for rheumatoid arthritis treatment. The results showed that a nanoaptamer with a size range of 241 nm was produced. The entrapment efficacy was 90% with a biodistribution showing a high hepatic uptake (>98%). The results in vivo showed a potent effect in arthritis experimental model, especially in low doses. The results corroborate the applicability of this nanosystem for RA treatment.

Intra-articular use of radium dichloride ([223Ra] RaCl2) showed relevant anti-inflammatory response on experimental arthritis model

Rheumatoid arthritis (RA) is an inflammatory chronic autoimmune disease. The treatment of RA is difficult and, in many cases, ineffective, and the arsenal of drugs is limited. Due the longevity of the disease, RA may cause extreme musculoskeletal disorders with a high impact on quality of life. Also, RA is related with severe comorbidities decreasing the life expectancy. Finally, RA has been reported to impact in economy and healthy public. In this direction, the necessity to discover new strategies to efficiently treat RA is immediate. In this direction, we have reported the use of low doses of [223Ra] RaCl2 (radium dichloride) as intra-articular injection to treat RA. Mice were post-treated with [223Ra] RaCl2 (1.48 µCi; i.a.) 24 h after zymosan stimulus. Zymosan-induced arthrithis is responsible for leucocyte recruitment (total leukocytes, neutrophils, and mononuclear cells), which were inhibited by intra-articular injection of [223Ra] RaCl2 (69%, 77%, and 66%, respectively).

The emerging role of neutrophils in autoimmune-associated disorders: effector, predictor, and therapeutic targets

Neutrophils are essential components of the immune system and have vital roles in the pathogenesis of autoimmune disorders. As effector cells, neutrophils promote autoimmune disease by releasing cytokines and chemokines cascades that accompany inflammation, neutrophil extracellular traps (NETs) regulating immune responses through cell-cell interactions. More recent evidence has extended functions of neutrophils. Accumulating evidence implicated neutrophils contribute to tissue damage during a broad range of disorders, involving rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), primary sjögren's syndrome (pSS), multiple sclerosis (MS), crohn's disease (CD), and gout. A variety of studies have reported on the functional role of neutrophils as therapeutic targets in autoimmune diseases. However, challenges and controversies in the field remain. Enhancing our understanding of neutrophils' role in autoimmune disorders may further advance the development of new therapeutic approaches.

Studies on host-foodborne bacteria in intestinal three-dimensional cell culture model indicate possible mechanisms of interaction

Spheroids of intestinal cells (Caco-2) were used to evaluate the adhesion/invasion ability of Listeria monocytogenes (pathogen) and Lactobacillus sakei 1 (potential probiotic). Besides, transcriptomic analyses of Caco-2 cells in three dimensional cultures were done, with the aim of revealing possible host-foodborne bacteria interactions. Result of adhesion assay for L. monocytogenes in Caco-2 spheroids was 22.86 ± 0.33%, but it was stimulated in acidic pH (4.5) and by the presence of 2% sucrose (respectively, 32.56 ± 1.35% and 33.25 ± 1.26%). Conversely, the invasion rate of L. monocytogenes was lower at pH 4.5, in comparison with non-stressed controls (18.89 ± 1.05% and 58.65 ± 0.30%, respectively). L. sakei 1 adhered to Caco-2 tridimensional cell culture (27.30 ± 2.64%), with no invasiveness. There were 19 and 21 genes down and upregulated, respectively, in tridimensional Caco-2 cells, upon infection with L. monocytogenes, which involved immunity, apoptosis; cytoprotective responses, cell signalling-regulatory pathways. It was evidenced despite activation or deactivation of several pathways in intestinal cells to counteract infection, the pathogen was able to hijack many host defense mechanisms. On the other hand, the probiotic candidate L. sakei 1 was correlated with decreased transcription of two genes in Caco-2 cells, though it stimulated the expression of 14 others, with diverse roles in immunity, apoptosis, cytoprotective response and cell signalling-regulatory pathways. Our data suggest the use of tridimensional cell culture to mimic the intestinal epithelium is a good model for gathering broad information on the putative mechanisms of interaction between host and bacteria of importance for food safety, which can serve as a basis for further in-depth investigation.

Biochanin A attenuates zymosan-induced arthritis in mice similarly to 17-β estradiol: an alternative to hormone replacement therapy?

OBJECTIVE AND DESIGN

Biochanin A (BCA), a phytoestrogen, has various pharmacological properties. This study was conducted to compare BCA's therapeutic property against 17-β estradiol replacement therapy in zymosan-induced arthritis (ZIA) in mice. Additionally, we further investigated in vitro the anti-inflammatory action on neutrophils.

TREATMENT

Ovariectomized (OVX) and non-OVX mice were pretreated with BCA (1, 3 and 9 mg/kg) or estrogen (50 µg/kg) for 14 days prior to ZIA. Neutrophils were pretreated with BCA (1, 10 and 100 μM) for 1 h prior to phorbol 12-myristate 13-acetate.

METHODS

Anti-inflammatory effects of BCA were evaluated by cellular infiltrate, paw edema and cytokine measurement. In vitro, apoptosis was assessed by morphology and flow cytometry. Neutrophil extracellular traps (NET) were determined by fluorescent microscopy and DNA release. Statistical differences were determined by one- or two-way ANOVA.

RESULTS

BCA inhibited neutrophil accumulation, paw edema and proinflammatory cytokine (TNF-α and IFN-γ) and increased anti-inflammatory cytokines (IL-4 and IL-10) in OVX and non-OVX mice, similar to 17-β estradiol replacement therapy. In vitro, BCA increased apoptosis and consequently reduced NETs.

CONCLUSION

BCA has a notable anti-inflammatory effect, similar to 17-β estradiol, and is especially effective for treatment of ZIA. These results suggest that BCA may be promising for the treatment of postmenopausal arthritis.

Fever Induced by Zymosan A and Polyinosinic-Polycytidylic Acid in Female Rats: Influence of Sex Hormones and the Participation of Endothelin-1

Sex differences in the immune response can also affect the febrile response, particularly the fever induced by lipopolysaccharide (LPS). However, other pathogen-associated molecular patterns, such as zymosan A (Zym) and polyinosinic-polycytidylic acid (Poly I:C), also induce fever in male rats with a different time course of cytokine release and different mediators such as endothelin-1 (ET-1). This study investigated whether female sex hormones affect Zym- and Poly I:C-induced fever and the involvement of ET-1 in this response. The fever that was induced by Zym and Poly I:C was higher in ovariectomized (OVX) female rats compared with sham-operated female rats. Estrogen replacement in OVX females reduced Zym- and Poly I:C-induced fever. The ET_B receptor antagonist BQ788 reversed the LPS-induced fever in cycling females but not in OVX females. BQ788 did not alter the fever that was induced by Zym or Poly I:C in either cycling or OVX females. These findings suggest that the febrile response in cycling females is lower, independently of the stimulus that is inducing it and is probably controlled by estrogen. Also, ET-1 seems to participate in the febrile response that was induced by LPS in males and cycling females but not in the LPS-induced fever in OVX females. Additionally, ET-1 was not involved in the febrile response that was induced by Zym or Poly I:C in females.

Synthesis, Characterization, and Biological Activity of Aminated Zymosan

Zymosan (ZM), a naturally occurring insoluble macromolecule obtained from the cell wall of Saccharomyces cerevisiae, is used as a functional food (as dietary fiber), phagocytic stimulus, and immune potentiator. The present study aimed to increase its solubility and evaluate its immunological application. ZM was converted into soluble 6-amino-6-deoxy-β-(1-3)-glucan of a molecular weight of 296 kDa by reduction. Detailed structural characterization of aminated ZM was determined by Fourier transform infrared spectroscopy and two-dimensional NMR analysis (2D, COSY, TOCSY, ROSEY, NOSEY, and HSQC). Aminated ZM was biocompatible with Raw 264.7 macrophage cell lines up to a concentration of 100 μg/mL. Rhodamine tagging revealed that the aminated ZM microparticles were found localized within the nucleus of Raw 264.7 cells. Both native and aminated ZM showed a similar expression pattern of inflammatory genes in Raw 264.7.

ET-traps offer a potential therapeutic tool for use in different autoimmune diseases

Research shows that endothelin (ET)-traps are a potential therapy for diabetes. Given that type 1 diabetes mellitus (T1DM) is an autoimmune disorder, ET-traps could also have an efficacious, therapeutic effect on other autoimmune diseases associated with pathologically elevated ET-1. Here, we describe those different autoimmune diseases that might benefit from a tool such as ET-traps, which potently sequester these elevated levels of ET-1. We also discuss the current use of ET receptor (ETR) antagonists and the associated adverse effects, and how ET-traps are associated with no toxicity and potentially offer a superior alternative. ET-traps could be used against different autoimmune diseases and, therefore, are a novel therapeutic tool for such conditions.

Involvement of Endothelin Receptors in Peripheral Sensory Neuropathy Induced by Oxaliplatin in Mice

The aim of this study was to evaluate the participation of the endothelin ET_A and ET_B receptors and the effects of bosentan in oxaliplatin-induced peripheral sensory neuropathy (OIN) in mice. Adult male Swiss mice received 1 mg/kg of oxaliplatin intravenously, twice a week for 5 weeks. Dorsal root ganglia (DRG) and spinal cords were removed for evaluation of the endothelin ET_A and ET_B receptor expression. Afterwards, selective (BQ-123 and BQ-788; 10 nmol in 30 μL, intraplantarly) and non-selective (bosentan, 100 mg/kg, orally) antagonists were administered in order to evaluate the involvement of the endothelin receptors in OIN. Mechanical and thermal nociception tests were performed once a week for 56 days. Oxaliplatin induced mechanical and thermal hypersensitivity and increased the endothelin ET_A receptor expression in both the DRG and spinal cord (P < 0.05). Endothelin ET_B receptor expression was increased in the DRG (P < 0.05) but not in the spinal cord. Both endothelin ET_A and ET_B receptor selective antagonists partially prevented mechanical hyperalgesia in mice with OIN (P < 0.05). Moreover, bosentan prevented mechanical and thermal hypersensitivity in oxaliplatin-treated mice (P < 0.05). In conclusion, both endothelin ET_A and ET_B receptors seem to be involved in the OIN in mice and they should be considered possible targets for the management of this clinical feature.

Targeting nitric oxide as a key modulator of sepsis, arthritis and pain

Nitric oxide (NO) is produced by enzymatic activity of neuronal (nNOS), endothelial (eNOS), and inducible nitric oxide synthase (iNOS) and modulates a broad spectrum of physiological and pathophysiological conditions. The iNOS isoform is positively regulated at transcriptional level and produces high levels of NO in response to inflammatory mediators and/or to pattern recognition receptor signaling, such as Toll-like receptors. In this review, we compiled the main contributions of our group for understanding of the role of NO in sepsis and arthritis outcome and the peripheral contributions of NO to inflammatory pain development. Although neutrophil iNOS-derived NO is necessary for bacterial killing, systemic production of high levels of NO impairs neutrophil migration to infections through inhibiting neutrophil adhesion on microcirculation and their locomotion. Moreover, neutrophil-derived NO contributes to multiple organ dysfunction in sepsis. In arthritis, NO is chief for bacterial clearance in staphylococcal-induced arthritis; however, it contributes to articular damage and bone mass degradation. NO produced in inflammatory sites also downmodulates pain. The mechanism involved in analgesic effect and inhibition of neutrophil migration is dependent on the activation of the classical sGC/cGMP/PKG pathway. Despite the increasing number of studies performed after the identification of NO as an endothelium-derived relaxing factor, the underlying mechanisms of NO in inflammatory diseases remain unclear.

Anti-inflammatory action of an alkaloid, fraction and extract from Alchornea glandulosa in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Alchornea glandulosa (Euphorbiaceae) has traditionally been used in medicine for treating immune-mediated inflammatory diseases.

AIM OF STUDY

This work aimed to evaluate the anti-inflammatory effects of a methanolic extract of leaves from A. glandulosa (MEAG), as well as the ethyl acetate fraction (EAFAG) and isolated compound guanidine alkaloid N-1, N-2, N-3-triisopentenylguanidine (AG-1), in experimental in vivo models of inflammation in mice. We also investigated this extract's phenols, flavonoids and flavonol compounds.

MATERIALS AND METHODS

MEAG (extracted by maceration with methanol), EAFAG (fraction resulting from the partition of the methanolic extract with ethyl acetate) and AG-1 (alkaloid isolated by chromatographic methods) were analysed. MEAG and EAFAG were analysed by HPLC/DAD. The effects of MEAG (30, 100 and 300 mg/kg), EAFAG (30, 100 and 300 mg/kg) and AG-1 (5 and 30 mg/kg) were studied in the following experimental mouse models: paw oedema and myeloperoxidase (MPO) activity, croton-oil-induced ear oedema, leukocyte migration in a pleurisy model induced by carrageenan and zymosan induction of joint inflammation.

RESULTS

MEAG and EAFAG were analysed by LC/DAD, and phenolic acids (gallic acid and caffeic acid) and flavonoids (myricetin-3-O-α-rhamnopyranoside and quercetin) were detected. MEAG, EAFAG and AG-1 were used in the carrageenan-induced paw oedema model and showed maximum inhibitions of 60.10% (MEAG, 2 h, 300 mg/kg) and 66.21% (EAFAG, 2 h, 300 mg/kg). AG-1 at 5 mg/kg showed significant inhibition, ranging from 60.92% to 63.13%, at all evaluated times, and the 30 mg/kg dose showed inhibition of 42.12% (1 h) and 40.36% (2 h). MEAG (37%, 46.1% and 68.11%) and EAFAG (31%, 42.21% and 48.93%), at doses of 30, 100 and 300 mg/kg, respectively, significantly reduced the increase in MPO activity, and AG-1 (5 and 30 mg/kg) showed inhibition of 64.62% and 65.12%, respectively. In the pleurisy model, MEAG (300 mg/kg), EAFAG (300 mg/kg) and AG-1 (30 mg/kg) significantly reduced the migration of total leukocytes with maximal inhibition of 80.90%, 83.17% and 89.39%, respectively. In the croton oil model, pretreatment with MEAG (0.1, 0.3 and 1 mg/ear) increased the diameter of the right ear (30.32%, 48.87% and 53.09%, respectively). Finally, MEAG (100 and 300 mg/kg; 33.11% and 56.03%) and EAFAG (100 and 300 mg/kg; 36.89% and 50.53%) reduced zymosan-induced oedema formation.

CONCLUSIONS

To the best of our knowledge, these results are the first to demonstrate that A. glandulosa exhibits oral and topical anti-inflammatory activity. This study detected alkaloid and phenol/polyphenolic compounds in A. glandulosa, which may help to explain the ethnobotanical use of this plant in traditional medicine in Brazil to treat immune-mediated inflammatory diseases.

The citrus flavanone naringenin attenuates zymosan-induced mouse joint inflammation: induction of Nrf2 expression in recruited CD45+ hematopoietic cells

BACKGROUND

Naringenin is a biologically active analgesic, anti-inflammatory, and antioxidant flavonoid. Naringenin targets in inflammation-induced articular pain remain poorly explored.

METHODS

The present study investigated the cellular and molecular mechanisms involved in the analgesic/anti-inflammatory effects of naringenin in zymosan-induced arthritis. Mice were pre-treated orally with naringenin (16.7-150 mg/kg), followed by intra-articular injection of zymosan. Articular mechanical hyperalgesia and oedema, leucocyte recruitment to synovial cavity, histopathology, expression/production of pro- and anti-inflammatory mediators and NFκB activation, inflammasome component expression, and oxidative stress were evaluated.

RESULTS

Naringenin inhibited articular pain and oedema in a dose-dependent manner. The dose of 50 mg/kg inhibited leucocyte recruitment, histopathological alterations, NFκB activation, and NFκB-dependent pro-inflammatory cytokines (TNF-α, IL-1β, and IL-33), and preproET-1 mRNA expression, but increased anti-inflammatory IL-10. Naringenin also inhibited inflammasome upregulation (reduced Nlrp3, ASC, caspase-1, and pro-IL-1β mRNA expression) and oxidative stress (reduced gp91^phox mRNA expression and superoxide anion production, increased GSH levels, induced Nrf2 protein in CD45⁺ hematopoietic recruited cells, and induced Nrf2 and HO-1 mRNA expression).

CONCLUSIONS

Naringenin presents analgesic and anti-inflammatory effects in zymosan-induced arthritis by targeting its main physiopathological mechanisms. These data highlight this flavonoid as an interesting therapeutic compound to treat joint inflammation, deserving additional pre-clinical and clinical studies.

Central mediators of the zymosan-induced febrile response

BACKGROUND

Zymosan is a fungal cell wall protein-carbohydrate complex that is known to activate inflammatory pathways through the Toll-like receptors and is commonly used to induce fever. Nevertheless, the central mediators that are involved in the zymosan-induced febrile response are only partially known.

METHODS

The present study evaluated the participation of prostaglandins, substance P, endothelin-1 (ET-1), and endogenous opioids (eOPs) in the zymosan-induced febrile response by using inhibitors and antagonists in male Wistar rats.

RESULTS

Both nonselective (indomethacin) and selective (celecoxib) cyclooxygenase inhibitors reduced the febrile response induced by an intraperitoneal (i.p.) injection of zymosan. Indomethacin also blocked the increase in the prostaglandin E2 levels in the cerebrospinal fluid. An intracerebroventricular injection of the neurokinin-1, ETB, and μ-opioid receptor antagonists also reduced the febrile response induced by the i.p. injected zymosan. Moreover, the μ-opioid receptor antagonist CTAP also reduced the febrile response induced by intra-articular injection of zymosan.

CONCLUSIONS

These results demonstrate that prostaglandins, substance P, ET-1, and eOPs are central mediators of the zymosan-induced febrile response.

Quercetin attenuates zymosan-induced arthritis in mice

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by articular lesions, recruitment of inflammatory cells and increased levels of pro-inflammatory cytokine. The intra-articular administration of zymosan is an experimental model that promotes inflammatory parameters resembling RA. Therefore, this model was used to investigate the efficacy of quercetin as a treatment of articular inflammation. Treatment with quercetin dose-dependently reduced zymosan-induced hyperalgesia, articular edema and the recruitment of neutrophils to the knee joint cavity. Histological analysis confirmed that quercetin inhibited zymosan-induced arthritis. The treatment with quercetin also inhibited zymosan-induced depletion of reduced glutathione (GSH) levels, TNFα and IL-1β production, and gp91^phox, prepro-endothelin-1 (preproET-1), and cyclooxygenase-2 mRNA expression. These molecular effects of quercetin were related to the inhibition of the nuclear factor kappa-B and induction of Nuclear factor erythroid 2- related factor (Nrf2)/home oxygenase (HO-1) pathway. Thus, quercetin exerted anti-inflammatory, analgesic and antioxidant effects in experimental arthritis, suggesting quercetin is a possible candidate for arthritis treatment.

Antioxidant, anti-rheumatic and anti-inflammatory investigation of extract and dicentrinone from Duguetia furfuracea (A. St.-Hil.) Benth. & Hook. f

ETHNOPHARMACOLOGICAL RELEVANCE

The preparations of teas and syrups using Duguetia furfuracea have been used in folk medicine to treat rheumatism and back pain. Several rheumatic diseases are anti-inflammatory and are treated with several anti-inflammatories.

AIM OF THE STUDY

The objective of this work were to evaluate the chemical investigation of methanolic extract obtained from leaves of D. furfuracea (MEDF) and test the MEDF, such as chloroform (CF), ethyl acetate (EAF) and hydromethanol (HMF) fractions and the alkaloid dicentrinone (DF-1) in vitro antioxidant effects and in vivo models of inflammation.

MATERIAL AND METHODS

MEDF and CF were analyzed by LC-PDA and the results revealed the presence of alkaloid aporphine and oxoaporphine. The concentrations of total phenols, flavonoids and flavonols were determined. Additionally, MEDF, fractions and dicentrinone were evaluated free radical scavenging activity 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and peroxidation β-carotene/linoleic acid and malondialdehyde (MDA) assays. The anti-inflammatory effects of MEDF, fractions and dicentrinone were studied in carrageenan-induced paw edema. The anti-rheumatic potential was studied in air pouch model and zymosan-induced arthritis.

RESULTS

CF fractionation resulted in the isolation of the oxaporphine alkaloid dicentrinone (DF-1). The highest phenols (624.37mg GAE/g extract), flavonoids (580.51mg QE/g extract) and flavonols (254.44mg QE/g extract), concentration was found in extract. In antioxidant tests, MEDF exhibited the highest scavenging activity and lipoperoxidation. The extract (30-300mg/kg) and all tested fractions inhibited the edema induced by carrageenan. The oral administration of DF-1 inhibited both edema associated with carrageenan-induced inflammation in mice. In air pouch model of inflammation, MEDF (30-300mg/kg) and DF-1 (100mg/kg) inhibited leukocyte migration and plasmatic leakage induced by carrageenan in mice. Finally, MEDF (100mg/kg) did not alter zymozan-induced arthritis in mice.

CONCLUSION

The results showed that D. furfuracea exhibits antioxidant, anti-rheumatic potential and anti-inflammatory activity. The presence of the alkaloid dicentrinone in extract and CF fraction could be responsible, at least in part, for the observed effects.

Potential role for ET-2 acting through ETA receptors in experimental colitis in mice

OBJECTIVE AND DESIGN

This study attempted to clarify the roles of endothelins and mechanisms associated with ET_A/ET_B receptors in mouse models of colitis.

MATERIALS AND METHODS

Colitis was induced by intracolonic administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS, 1.5 mg/animal) or dextran sulfate sodium (DSS, 3%). After colitis establishment, mice received Atrasentan (ET_A receptor antagonist, 10 mg/kg), A-192621 (ET_B receptor antagonist, 20 mg/kg) or Dexamethasone (1 mg/kg) and several inflammatory parameters were assessed, as well as mRNA levels for ET-1, ET-2 and ET receptors.

RESULTS

Atrasentan treatment ameliorates TNBS- and DSS-induced colitis. In the TNBS model was observed reduction in macroscopic and microscopic score, colon weight, neutrophil influx, IL-1β, MIP-2 and keratinocyte chemoattractant (KC) levels, inhibition of adhesion molecules expression and restoration of IL-10 levels. However, A192621 treatment did not modify any parameter. ET-1 and ET-2 mRNA was decreased 24 h, but ET-2 mRNA was markedly increased at 48 h after TNBS. ET-2 was able to potentiate LPS-induced KC production in vitro. ET_A and ET_B receptors mRNA were increased at 24, 48 and 72 h after colitis induction.

CONCLUSIONS

Atrasentan treatment was effective in reducing the severity of colitis in DSS- and TNBS-treated mice, suggesting that ET_A receptors might be a potential target for inflammatory bowel diseases.

Differential regulation of oxidative stress and cytokine production by endothelin ETA and ETB receptors in superoxide anion-induced inflammation and pain in mice

The present study investigated whether endothelin-1 acts via ET_A or ET_B receptors to mediate superoxide anion-induced pain and inflammation. Mice were treated with clazosentan (ET_A receptor antagonist) or BQ-788 (ET_B receptor antagonist) prior to stimulation with the superoxide anion donor, KO₂. Intraplantar treatment with 30 nmol of clazosentan or BQ-788 reduced mechanical hyperalgesia (47% and 42%), thermal hyperalgesia (68% and 76%), oedema (50% and 30%); myeloperoxidase activity (64% and 32%), and overt-pain like behaviours, such as paw flinching (42% and 42%) and paw licking (38% and 62%), respectively. Similarly, intraperitoneal treatment with 30 nmol of clazosentan or BQ-788 reduced leukocyte recruitment to the peritoneal cavity (58% and 32%) and abdominal writhing (81% and 77%), respectively. Additionally, intraplantar treatment with clazosentan or BQ-788 decreased spinal (45% and 41%) and peripheral (47% and 47%) superoxide anion production as well as spinal (47% and 47%) and peripheral (33% and 54%) lipid peroxidation, respectively. Intraplantar treatment with clazosentan, but not BQ-788, reduced spinal (71%) and peripheral (51%) interleukin-1 beta as well as spinal (59%) and peripheral (50%) tumor necrosis factor-alpha production. Therefore, the present study unveils the differential mechanisms by which ET-1, acting on ET_A or ET_B receptors, regulates superoxide anion-induced inflammation and pain.

Anti-inflammatory Effect of Methyl Gallate on Experimental Arthritis: Inhibition of Neutrophil Recruitment, Production of Inflammatory Mediators, and Activation of Macrophages

Methyl gallate (MG) is a prevalent phenolic acid in the plant kingdom, and its presence in herbal medicines might be related to its remarkable biological effects, such as its antioxidant, antitumor, and antimicrobial activities. Although some indirect evidence suggests anti-inflammatory activity for MG, there are no studies demonstrating this effect in animal models. Herein, we demonstrated that MG (0.7-70 mg/kg) inhibited zymosan-induced experimental arthritis in a dose-dependent manner. The oral administration of MG (7 mg/kg) attenuates arthritis induced by zymosan, affecting edema formation, leukocyte migration, and the production of inflammatory mediators (IL-1β, IL-6, TNF-α, CXCL-1, LTB4, and PGE2). Pretreatment with MG inhibited in vitro neutrophil chemotaxis elicited by CXCL-1, as well as the adhesion of these cells to TNF-α-primed endothelial cells. MG also impaired zymosan-stimulated macrophages by inhibiting IL-6 and NO production, COX-2 and iNOS expression, and intracellular calcium mobilization. Thus, MG is likely to present an anti-inflammatory effect by targeting multiple cellular events such as the production of various inflammatory mediators, as well as leukocyte activation and migration.

Anti-inflammatory effect of Schinus terebinthifolius Raddi hydroalcoholic extract on neutrophil migration in zymosan-induced arthritis

ETHNOPHARMACOLOGICAL RELEVANCE

Schinus terebinthifolius is a species of plant from the Anacardiaceae family, which can be found in different regions of Brazil. Schinus is popularly known as aroeirinha, aroeira-vermelha, or Brazilian pepper. In folk medicine, S. terebinthifolius is used for several disorders, including inflammatory conditions, skin wounds, mucosal membrane ulcers, respiratory problems, gout, tumors, diarrhea and arthritis. According to chemical analyses, gallic acid, methyl gallate and pentagalloylglucose are the main components of hydroalcoholic extracts from S. terebinthifolius leaves. In the present study, we demonstrated the ability of a hydroalcoholic extract to inhibit cell migration in arthritis and investigated the mechanisms underlying this phenomenon.

MATERIALS AND METHODS

The anti-inflammatory effect of S. terebinthifolius hydroalcoholic leaf extract (ST-70) was investigated in a zymosan-induced experimental model of inflammation. Male Swiss and C57Bl/6 mice received zymosan (100 µg/cavity) via intra-thoracic (i.t.) or intra-articular (i.a.) injection after oral pre-treatment with ST-70. The direct action of ST-70 on neutrophils was evaluated via chemotaxis.

RESULTS

ST-70 exhibited a dose-dependent effect in the pleurisy model. The median effective dose (ED50) was 100mg/kg, which inhibited 70% of neutrophil accumulation when compared with the control group. ST-70 reduced joint diameter and neutrophil influx for synovial tissues at 6h and 24h in zymosan-induced arthritis. Additionally, ST-70 inhibited synovial interleukin (IL)-6, IL-1β, keratinocyte-derived chemokine (CXCL1/KC) and Tumor Necrosis Factor (TNF)-α production at 6h and CXCL1/KC and IL-1β production at 24h. The direct activity of ST-70 on neutrophils was observed via the impairment of CXCL1/KC-induced chemotaxis in neutrophils. Oral administration of ST-70 did not induce gastric damage. Daily administration for twenty days did not kill any animals. In contrast, similar administrations of diclofenac induced gastric damage and killed all animals by the fifth day.

CONCLUSIONS

Our results demonstrated significant anti-inflammatory effects of ST-70, suggesting a putative use of this herb for the development of phytomedicines to treat inflammatory diseases, such as joint inflammation.

Bosentan, a mixed endothelin receptor antagonist, inhibits superoxide anion-induced pain and inflammation in mice

Bosentan is a mixed endothelin receptor antagonist widely used to treat patients with pulmonary arterial hypertension, and the emerging literature suggests bosentan as a potent anti-inflammatory drug. Superoxide anion is produced in large amounts during inflammation, stimulates cytokine production, and thus contributes to inflammation and pain. However, it remains to be determined whether endothelin contributes to the inflammatory response triggered by the superoxide anion. The present study investigated the effects of bosentan in a mouse model of inflammation and pain induced by potassium superoxide, a superoxide anion donor. Male Swiss mice were treated with bosentan (10-100 mg/kg) by oral gavage, 1 h before potassium superoxide injection, and the inflammatory response was evaluated locally and at spinal cord (L4-L6) levels. Bosentan (100 mg/kg) inhibited superoxide anion-induced mechanical and thermal hyperalgesia, overt pain-like behavior (abdominal writhings, paw flinching, and licking), paw edema, myeloperoxidase activity (neutrophil marker) in the paw skin, and leukocyte recruitment in the peritoneal cavity. Bosentan also inhibited superoxide anion-induced interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) production, while it enhanced IL-10 production in the paw skin and spinal cord. Bosentan inhibited the reduction of antioxidant capacity (reduced glutathione, ferric reducing antioxidant power, and ABTS radical scavenging ability) induced by the superoxide anion. Finally, we demonstrated that intraplantar injection of potassium superoxide induces the mRNA expression of prepro-endothelin-1 in the paw skin and spinal cord. In conclusion, our results demonstrated that superoxide anion-induced inflammation, pain, cytokine production, and oxidative stress depend on endothelin; therefore, these responses are amenable to bosentan treatment.

Analysis of the anti-inflammatory and chemopreventive potential and description of the antimutagenic mode of action of the Annona crassiflora methanolic extract

CONTEXT

Annona crassiflora Mart. (Annonaceae) is a medicinal plant that is widely used in folk medicine, which leads to its investigation as a potential source of new pharmacological principles.

OBJECTIVE

This study describes the anti-inflammatory, antiallodynic, and antimutagenic/chemopreventive activities of the leaves A. crassiflora methanolic extract. Its antimutagenic mode of action was analyzed in a plant or animal experimental model.

MATERIALS AND METHODS

Total flavonoids were quantified by spectrophotometry at 415 nm and its composition was analyzed by (1)H NMR spectra. Animals received orally, 30, 100, and 300 mg/kg of extract in both tests, carrageenan-induced paw edema and myeloperoxidase activity. Animals were treated with 100 and 300 mg/kg, in all the analyzed tests, pleural cell migration and protein exudation, carrageenan-induced cell migration into the pouch, induction of joint inflammation and carrageenan-induced allodynia response in the mouse paw. To evaluate the antimutagenic/chemopreventive activity through the Allium cepa test, we used 5, 10, and 15 mg/L of extract, and for the micronucleus test in the peripheral blood, we used the dose of 15 mg/kg.

RESULTS

The fractionation of the ethyl acetate (EA) fraction, resulting from the partition of the methanol extract of the A. crassiflora, afforded through chromatographic methods resulted in the isolation of kaempferol 3-O-β-glucoside and kaempferol 3-O-β-diglucoside. Oral treatment with 100 and 300 mg/kg of extract significantly inhibited the carrageenan-induced edema formation, with inhibitions of 53 ± 7% and 47 ± 10%; in MPO activity, the observed inhibitions were 60 ± 7% for 100 mg/kg treatment and 63 ± 7% for 300 mg/kg. The ACME reduced significantly the total leukocytes (an inhibition of 78 ± 9% with 100 mg/kg and 90 ± 7% with 300 mg/kg) and protein levels (approximately 100% inhibition with both doses) in the pleurisy model. In carrageenan-induced leukocyte migration into the pouch, the extract inhibited leukocyte migration only when administered 300 mg/kg per dose (the reduction was 43 ± 5%). Pretreatment with extract failed to reduce the zymosan-induced edema formation and did not inhibit the carrageenan-induced mechanical allodynia. Damage reduction in Allium cepa tested with different concentrations (5, 10, and 15 mg/L) was 66.17, 75.75, and 69.19% for the pre-treatment; 72.72, 33.33, and 22.22% for the simple simultaneous treatment; 100.50, 93.93, and 102.52% for the simultaneous treatment with pre-incubation; 89.39, 79.79, and 84.34%; for the post-treatment, and 86.36, 81.31, and 93.43% for the continuous treatment. The antimutagenic evaluation in the micronucleous test showed a damage reduction of 75.00 and 64.58% for the pre-treatment and simultaneous protocols, respectively. The post-treatment protocol increased the cyclophosphamide effects in 45.83%.

CONCLUSION

These results suggest that this medicinal plant has chemopreventive and anti-inflammatory therapeutic potential.

The emerging role of endothelin-1 in the pathogenesis of subchondral bone disturbance and osteoarthritis

Mounting evidence suggests reconceptualizing osteoarthritis (OA) as an inflammatory disorder. Trauma and obesity, the common risk factors of OA, could trigger the local or systemic inflammatory cytokines cascade. Inflammatory bone loss has been well documented; yet it remains largely unknown about the link between the inflammation and hypertrophic changes of subchondral bone seen in OA, such as osteophytosis and sclerosis. Amid a cohort of inflammatory cytokines, endothelin-1 (ET-1) could stimulate the osteoblast-mediated bone formation in both physiological (postnatal growth of trabecular bone) and pathological conditions (bone metastasis of prostate or breast cancer). Also, ET-1 is known as a mitogen and contributes to fibrosis in various organs, e.g., skin, liver, lung, kidney heart and etc., as a result of inflammatory or metabolic disorders. Subchondral bone sclerosis shared the similarity with fibrosis in terms of the overproduction of collagen type I. We postulated that ET-1 might have a hand in the subchondral bone sclerosis of OA. Meanwhile, ET-1 was also able to stimulate the production of matrix metalloproteinase (MMP)-1 and 13 by articular chondrocytes and synoviocytes, by which it might trigger the enzymatic degradation of articular cartilage. Taken together, ET-1 signaling may play a role in destruction of bone-cartilage unit in the pathogenesis of OA; it warrants further investigations to potentiate ET-1 as a novel diagnostic biomarker and therapeutic target for rescue of OA.

Cytokines, but not corticotropin-releasing factor and endothelin-1, participate centrally in the febrile response in zymosan-induced arthritis in rats

Recent literature has revealed that centrally generated prostaglandins participate in the febrile response in zymosan-induced arthritis in rats. However, it is not clear whether other centrally acting pyrogenic mediators such as cytokines, endothelins (ETs), and the corticotropin-releasing factor (CRF) contribute to the febrile response in this model. In the present study, rats were pretreated with intracerebroventricular (i.c.v.) injections of soluble TNF receptor I (sTNFRI), recombinant IL-1 receptor antagonist (IL-1ra), anti-rat IL-6 monoclonal antibody (AbIL-6), α-helical CRF9-41 (a nonselective CRF1/CRF2 receptor antagonist), BQ-123 (an ETA receptor antagonist), BQ-788 (an ETB receptor antagonist), and artificial cerebrospinal fluid (aCSF, control) prior to an intra-articular zymosan (4 mg) injection. Rectal temperatures were measured with a telethermometer. The administration of IL-1ra (200 µg), sTNFRI (500 ng), and AbIL-6 (5 µg) attenuated body temperature elevations after a zymosan injection. The administration of BQ-788 (3 pmol), BQ-123 (3 pmol), and α-helical CRF9-41 (25 µg) did not affect the zymosan-induced febrile response. All the compounds used to pretreat the animals did not significantly alter their basal body temperatures. Together, the results here demonstrate that the febrile response in zymosan-induced arthritis in rats depends on the centrally acting pyrogenic cytokines TNF-α, IL-1β, and IL-6, but does not depend on either CRF or ET-1.

Effect of gedunin on acute articular inflammation and hypernociception in mice

Gedunin, a natural limonoid from Meliaceae species, has been previously described as an antiinflammatory compound in experimental models of allergic inflammation. Here, we report the antiinflammatory and antinociceptive effects of gedunin in an acute model of articular inflammation induced by zymosan (500 μg/cavity; intra-articular) in C57BL/6 mice. Intraperitoneal (i.p.) pretreatment with gedunin (0.005–5 mg/kg) impaired zymosan-induced edema formation, neutrophil accumulation and hypernociception in mouse knee joints, due to decreased expression of preproET-1 mRNA and production of LTB₄, PGE₂, TNF-α and IL-6. Mouse post-treatment with gedunin (0.05 mg/kg; i.p.) 1 and 6 h after stimulation also impaired articular inflammation, by reverting edema formation, neutrophil accumulation and the production of lipid mediators, cytokines and endothelin. In addition, gedunin directly modulated the functions of neutrophils and macrophages in vitro. The pre-incubation of neutrophil with gedunin (100 µM) impaired shape change, adhesion to endothelial cells, chemotaxis and lipid body formation triggered by different stimuli. Macrophage pretreatment with gedunin impaired intracellular calcium mobilization, nitric oxide production, inducible nitric oxide synthase expression and induced the expression of the antiinflammatory chaperone heat shock protein 70. Our results demonstrate that gedunin presents remarkable antiinflammatory and anti-nociceptive effects on zymosan-induced inflamed knee joints, modulating different cell populations.

Protective effect of Et-1 receptor antagonist bosentan on paracetamol induced acute liver toxicity in rats

Paracetamol is one of the first rank drugs which cause hepatic damage during drug intoxications. Endothelin (ET) which is known as one of the most potent vasoactive agent has been shown to contribute in the pathophysiology of various diseases. We hypothesized that bosentan, which is a non-selective ET-1 receptor antagonist, can prevent liver damage. This study included 49 female rats. Groups; I: Healthy group, II: Paracetamol (2 g/kg orally). Groups 3, 4 and 5 received NAC 140 mg/kg (2 doses), BOS 45 mg/kg and BOS 90 mg/kg orally, respectively. 1 h after administration of pretreatment drugs, Groups 3, 4, 5 were given paracetamol. VI: received BOS 90 mg/kg. VII: received 140 mg/kg NAC (2 doses). According to biochemical results, TNF-α, ALT and AST levels were statistically increased in the paracetamol group, these parameters were improved in the bosentan groups. Paracetamol administration decreased SOD activity, GSH level and increased level of MDA in the liver, while bosentan administration significantly improved these parameters. In immunohistochemical staining ET-1 receptor expression was excessively increased in paracetamol group, but not in bosentan groups when compared to healthy control. All these results suggest that bosentan exerted protective effects against experimentally induced paracetamol toxicity in liver.

IL-33/ST2 signalling contributes to carrageenin-induced innate inflammation and inflammatory pain: role of cytokines, endothelin-1 and prostaglandin E2

BACKGROUND AND PURPOSE

IL-33 signals through ST2 receptors and induces adaptive and innate inflammation. IL-33/ST2 is involved in adaptive inflammation-induced pain. Here, we have investigated the contribution of IL-33/ST2-triggered mechanisms to carrageenin-induced innate inflammation.

EXPERIMENTAL APPROACH

Carrageenin- and IL-33-induced inflammatory responses were assessed in BALB/c- (WT) and ST2-deficient ((-/-) ) mice as follows: oedema (plethysmometer), myeloperoxidase activity (colorimetric assay), mechanical hyperalgesia (electronic version of von Frey filaments), cytokine levels (ELISA), PGE2 (RIA), mRNA expression (quantitative PCR), drug treatments targeting leukocyte recruitment (fucoidin), TNF-α (infliximab), CXCL1 (antibody to CXCL1), IL-1 (IL-1ra), endothelin ETA (clazosentan) and ETB (BQ788) receptors and COX (indomethacin).

KEY RESULTS

Carrageenin injection increased ST2 and IL-33 mRNA expression and IL-33 production in paw skin samples. Carrageenin-induced paw oedema, hyperalgesia and myeloperoxidase activity were reduced in ST2(-/-) compared with WT mice, effects mimicked by IL-33 injection in the paw. Furthermore, IL-33-induced hyperalgesia was reduced by fucoidin suggesting a role for recruited leukocytes in its hyperalgesic effect. IL-33-induced hyperalgesia in naïve mice was reduced by treatments targeting TNF, CXCL1, IL-1, endothelin receptors and COX while carrageenin-induced ST2-dependent TNF-α, CXCL1, IL-1β, IL-10 and PGE2 production and preproET-1 mRNA expression. Combining IL-33 and carrageenin at doses that were ineffective as single treatment induced significant hyperalgesia, oedema, myeloperoxidase activity and cytokine production in a ST2-dependent manner.

CONCLUSIONS AND IMPLICATIONS

IL-33/ST2 signalling triggers the production of inflammatory mediators contributing to carrageenin-induced inflammation. These data reinforces the importance of IL-33/ST2 signalling as a target in innate inflammation and inflammatory pain.

Dual role for Fcγ receptors in host defense and disease in Borrelia burgdorferi-infected mice

Arthritis in mice infected with the Lyme disease spirochete, Borrelia burgdorferi, results from the influx of innate immune cells responding to the pathogen in the joint and is influenced in part by mouse genetics. Production of inflammatory cytokines by innate immune cells in vitro is largely mediated by Toll-like receptor (TLR) interaction with Borrelia lipoproteins, yet surprisingly mice deficient in TLR2 or the TLR signaling molecule MyD88 still develop arthritis comparable to that seen in wild type mice after B. burgdorferi infection. These findings suggest that other, MyD88-independent inflammatory pathways can contribute to arthritis expression. Clearance of B. burgdorferi is dependent on the production of specific antibody and phagocytosis of the organism. As Fc receptors (FcγR) are important for IgG-mediated clearance of immune complexes and opsonized particles by phagocytes, we examined the role that FcγR play in host defense and disease in B. burgdorferi-infected mice. B. burgdorferi-infected mice deficient in the Fc receptor common gamma chain (FcεR_γ^−/− mice) harbored ~10 fold more spirochetes than similarly infected wild type mice, and this was associated with a transient increase in arthritis severity. While the elevated pathogen burdens seen in B. burgdorferi-infected MyD88^−/− mice were not affected by concomitant deficiency in FcγR, arthritis was reduced in FcεR_γ^−/−MyD88^−/− mice in comparison to wild type or single knockout mice. Gene expression analysis from infected joints demonstrated that absence of both MyD88 and FcγR lowers mRNA levels of proteins involved in inflammation, including Cxcl1 (KC), Xcr1 (Gpr5), IL-1beta, and C reactive protein. Taken together, our results demonstrate a role for FcγR-mediated immunity in limiting pathogen burden and arthritis in mice during the acute phase of B. burgdorferi infection, and further suggest that this pathway contributes to the arthritis that develops in B. burgdorferi-infected MyD88^−/− mice.

Trypanosoma cruzi invades host cells through the activation of endothelin and bradykinin receptors: a converging pathway leading to chagasic vasculopathy

BACKGROUND AND PURPOSE

Independent studies in experimental models of Trypanosoma cruzi appointed different roles for endothelin-1 (ET-1) and bradykinin (BK) in the immunopathogenesis of Chagas disease. Here, we addressed the hypothesis that pathogenic outcome is influenced by functional interplay between endothelin receptors (ET(A)R and ET(B)R) and bradykinin B(2) receptors (B(2)R).

EXPERIMENTAL APPROACH

Intravital microscopy was used to determine whether ETR/B(2)R drives the accumulation of rhodamine-labelled leucocytes in the hamster cheek pouch (HCP). Inflammatory oedema was measured in the infected BALB/c paw of mice. Parasite invasion was assessed in CHO over-expressing ETRs, mouse cardiomyocytes, endothelium (human umbilical vein endothelial cells) or smooth muscle cells (HSMCs), in the presence/absence of antagonists of B(2)R (HOE-140), ET(A)R (BQ-123) and ET(B)R (BQ-788), specific IgG antibodies to each GPCRs; cholesterol or calcium-depleting drugs. RNA interference (ET(A)R or ET(B)R genes) in parasite infectivity was investigated in HSMCs.

KEY RESULTS

BQ-123, BQ-788 and HOE-140 reduced leucocyte accumulation in HCP topically exposed to trypomastigotes and blocked inflammatory oedema in infected mice. Acting synergistically, ET(A)R and ET(B)R antagonists reduced parasite invasion of HSMCs to the same extent as HOE-140. Exogenous ET-1 potentiated T. cruzi uptake by HSMCs via ETRs/B(2)R, whereas RNA interference of ET(A)R and ET(B)R genes conversely reduced parasite internalization. ETRs/B(2)R-driven infection in HSMCs was reduced in HSMC pretreated with methyl-β-cyclodextrin, a cholesterol-depleting drug, or in thapsigargin- or verapamil-treated target cells.

CONCLUSIONS AND IMPLICATIONS

Our findings suggest that plasma leakage, a neutrophil-driven inflammatory response evoked by trypomastigotes via the kinin/endothelin pathways, may offer a window of opportunity for enhanced parasite invasion of cardiovascular cells.

Endothelin-1 induces neutrophil recruitment in adaptive inflammation via TNFα and CXCL1/CXCR2 in mice

Endothelin mediates neutrophil recruitment during innate inflammation. Herein we address whether endothelin-1 (ET-1) is involved in neutrophil recruitment in adaptive inflammation in mice, and its mechanisms. Pharmacological treatments were used to determine the role of endothelin in neutrophil recruitment to the peritoneal cavity of mice challenged with antigen (ovalbumin) or ET-1. Levels of ET-1, tumour necrosis factor α (TNFα), and CXC chemokine ligand 1 (CXCL1) were determined by enzyme-linked immunosorbent assay. Neutrophil migration and flow cytometry analyses were performed 4 h after the intraperitoneal stimulus. ET-1 induced dose-dependent neutrophil recruitment to the peritoneal cavity. Treatment with the non-selective ET(A)/ET(B) receptor antagonist bosentan, and selective ET(A) or ET(B) receptor antagonists BQ-123 or BQ-788, respectively, inhibited ET-1- and ovalbumin-induced neutrophil migration to the peritoneal cavity. In agreement with the above, the antigen challenge significantly increased levels of ET-1 in peritoneal exudates. The ET-1- and ovalbumin-induced neutrophil recruitment were reduced in TNFR1 deficient mice, and by treatments targeting CXCL1 or CXC chemokine receptor 2 (CXCR2); further, treatment with bosentan, BQ-123, or BQ-788 inhibited ET-1- and antigen-induced production of TNFα and CXCL1. Furthermore, ET-1 and ovalbumin challenge induced an increase in the number of cells expressing the Gr1(+) markers in the granulocyte gate, CD11c(+) markers in the monocyte gate, and CD4(+) and CD45(+) (B220) markers in the lymphocyte gate in an ET(A)- and ET(B)-dependent manner, as determined by flow cytometry analysis, suggesting that ET-1 might be involved in the recruitment of neutrophils and other cells in adaptive inflammation. Therefore, the present study demonstrates that ET-1 is an important mediator for neutrophil recruitment in adaptive inflammation via TNFα and CXCL1/CXCR2-dependent mechanism.

Bosentan, an endothelin receptor antagonist, ameliorates collagen-induced arthritis: the role of TNF-α in the induction of endothelin system genes

OBJECTIVE

Endothelins (ETs) are involved in several inflammatory events. The present study investigated the efficacy of bosentan, a dual ETA/ETB receptor antagonist, in collagen-induced arthritis (CIA) in mice.

TREATMENT

CIA was induced in DBA/1J mice. Arthritic mice were treated with bosentan (100 mg/kg) once a day, starting from the day when arthritis was clinically detectable.

METHODS

CIA progression was assessed by measurements of visual clinical score, paw swelling and hypernociception. Histological changes, neutrophil infiltration and pro-inflammatory cytokines were evaluated in the joints. Gene expression in the lymph nodes of arthritic mice was evaluated by microarray technology. PreproET-1 mRNA expression in the lymph nodes of mice and in peripheral blood mononuclear cells (PBMCs) was evaluated by real-time PCR. The differences were evaluated by one-way ANOVA or Student's t test.

RESULTS

Oral treatment with bosentan markedly ameliorated the clinical aspects of CIA (visual clinical score, paw swelling and hyperalgesia). Bosentan treatment also reduced joint damage, leukocyte infiltration and pro-inflammatory cytokine levels (IL-1β, TNFα and IL-17) in the joint tissues. Changes in gene expression in the lymph nodes of arthritic mice returned to the levels of the control mice after bosentan treatment. PreproET mRNA expression increased in PBMCs from rheumatoid arthritis (RA) patients but returned to basal level in PBMCs from patients under anti-TNF therapy. In-vitro treatment of PBMCs with TNFα upregulated ET system genes.

CONCLUSION

These findings indicate that ET receptor antagonists, such as bosentan, might be useful in controlling RA. Moreover, it seems that ET mediation of arthritis is triggered by TNFα.

Potent anti-inflammatory and antinociceptive activity of the endothelin receptor antagonist bosentan in monoarthritic mice

Introduction

Endothelins are involved in tissue inflammation, pain, edema and cell migration. Our genome-wide microarray analysis revealed that endothelin-1 (ET-1) and endothelin-2 (ET-2) showed a marked up-regulation in dorsal root ganglia during the acute phase of arthritis. We therefore examined the effects of endothelin receptor antagonists on the development of arthritis and inflammatory pain in monoarthritic mice.

Methods

Gene expression was examined in lumbar dorsal root ganglia two days after induction of antigen-induced arthritis (AIA) using mRNA microarray analysis. Effects of drug treatment were determined by repeated assessment of joint swelling, pain-related behavior, and histopathological manifestations during AIA.

Results

Daily oral administration of the mixed ET_A and ET_B endothelin receptor antagonist bosentan significantly attenuated knee joint swelling and inflammation to an extent that was comparable to dexamethasone. In addition, bosentan reduced inflammatory mechanical hyperalgesia. Chronic bosentan administration also inhibited joint swelling and protected against inflammation and joint destruction during AIA flare-up reactions. In contrast, the ET_A-selective antagonist ambrisentan failed to promote any detectable antiinflammatory or antinociceptive activity.

Conclusions

Thus, the present study reveals a pivotal role for the endothelin system in the development of arthritis and arthritic pain. We show that endothelin receptor antagonists can effectively control inflammation, pain and joint destruction during the course of arthritis. Our findings suggest that the antiinflammatory and antinociceptive effects of bosentan are predominantly mediated via the ET_B receptor.

Lipoxin A(4) attenuates zymosan-induced arthritis by modulating endothelin-1 and its effects

BACKGROUND AND PURPOSE

Lipoxin A(4) (LXA(4)) is a lipid mediator involved in the resolution of inflammation. Increased levels of LXA(4) in synovial fluid and enhanced expression of the formyl peptide receptor 2/lipoxin A(4) receptor (FPR2/ALX) in the synovial tissues of rheumatoid arthritis patients have been reported. Endothelins (ETs) play a pivotal pro-inflammatory role in acute articular inflammatory responses. Here, we evaluated the anti-inflammatory role of LXA(4), during the acute phase of zymosan-induced arthritis, focusing on the modulation of ET-1 expression and its effects.

EXPERIMENTAL APPROACH

The anti-inflammatory effects of LXA(4), BML-111 (agonist of FPR2/ALX receptors) and acetylsalicylic acid (ASA) pre- and post-treatments were investigated in a murine model of zymosan-induced arthritis. Articular inflammation was assessed by examining knee joint oedema; neutrophil accumulation in synovial cavities; and levels of prepro-ET-1 mRNA, leukotriene (LT)B(4), tumour necrosis factor (TNF)-α and the chemokine KC/CXCL1, after stimulation. The direct effect of LXA(4) on ET-1-induced neutrophil activation and chemotaxis was evaluated by shape change and Boyden chamber assays respectively.

KEY RESULTS

LXA(4), BML-111 and ASA administered as pre- or post-treatment inhibited oedema and neutrophil influx induced by zymosan stimulation. Zymosan-induced preproET-1 mRNA, KC/CXCL1, LTB(4) and TNF-α levels were also decreased after LXA(4) pretreatment. In vitro, ET-1-induced neutrophil chemotaxis was inhibited by LXA(4) pretreatment. LXA(4) treatment also inhibited ET-1-induced oedema formation and neutrophil influx into mouse knee joints.

CONCLUSION AND IMPLICATION

LXA(4) exerted anti-inflammatory effects on articular inflammation through a mechanism that involved the inhibition of ET-1 expression and its effects.

Suppressive effects of azithromycin on zymosan-induced production of proinflammatory mediators by human corneal epithelial cells

PURPOSE

In addition to its antibiotic effects, azithromycin has been noted to have anti-inflammatory activity, particularly in the context of microbial infections. This study was conducted to explore the suppressive effects of azithromycin on the production of proinflammatory mediators by human corneal epithelial cells (HCECs) stimulated by a fungal component, zymosan.

METHODS

Primary HCECs were cultured from donor corneal limbal explants and grown to subconfluence. The cells were treated with toll-like receptor (TLR) 2 agonist zymosan (1-50 μg/mL) for 4 to 48 hours, with or without preincubation with azithromycin (1-50 μg/mL), TLR2 antibody, or NF-κB activation inhibitor quinazoline (NF-κB-I). The cells were subjected to total RNA extraction, reverse transcription (RT), and real-time PCR using gene expression assays. Cells treated for 48 hours were used for immunofluorescence staining and Western blot analysis, and their medium supernatants were collected for protein quantitation by immunobead assays.

RESULTS

The mRNA expression and protein production of proinflammatory cytokines (TNF-α and IL-1β), chemokines (IL-8 and RANTES), and matrix metalloproteinases (MMP-1, -3, and -9) by HCECs were stimulated by zymosan in a concentration-dependent manner, with peak levels noted at 4 hours. These stimulated levels of proinflammatory mediators by zymosan were significantly inhibited by TLR2 antibody, NF-κB-I, or azithromycin, which blocked zymosan-induced NF-κB activation as determined by p65 protein nuclear translocation.

CONCLUSIONS

These findings demonstrated that the fungal component zymosan induces proinflammatory responses through TLR2 and NF-κB signaling pathways, whereas azithromycin suppresses its stimulation by blocking NF-κB activation in HCECs, suggesting the potential efficacy of this antibiotic for treating ocular surface inflammatory disorders.

Leukotriene B4 mediates gammadelta T lymphocyte migration in response to diverse stimuli

Herein, we investigated the involvement of the 5-LO-derived lipid mediator LTB(4) in gammadelta T cell migration. When injected into the i.pl. space of C57BL/6 mice, LTB(4) triggered gammadelta T lymphocyte mobilization in vivo, a phenomenon also observed in in vitro chemotaxis assays. The i.pl. injection of Escherichia coli endotoxin (LPS) triggered increased levels of LTB(4) in pleural cavities. The in vivo inhibition of LTB(4) biosynthesis by the 5-LO inhibitor zileuton or the FLAP inhibitor MK886 attenuated LPS-induced gammadelta T cell accumulation into pleural cavities. Accordingly, 5-LO KO mice failed to recruit gammadelta T cells into the inflammatory site after i.pl. LPS. Antagonists of the high-affinity LTB(4) receptor BLT1, CP105,696, and LY292476 also attenuated LPS-induced gammadelta T cell accumulation in pleural cavities as well as in vitro chemotaxis toward pleural washes obtained from LPS-simulated mice. LTB(4)/BLT1 also accounted for gammadelta T cell migration induced by i.pl. administration of Mycobacterium bovis BCG or antigen in sensitized mice. BLT1 was expressed on naïve, resident as well as LPS-recruited gammadelta T cells. Isolated gammadelta T cells were found to undergo F-actin cytoskeleton reorganization when incubated with LTB(4) in vitro, confirming that gammadelta T lymphocytes can respond directly to LTB(4). In addition to its direct effect on gammadelta T cells, LTB(4) triggered their accumulation indirectly, via modulation of CCL2 production in mouse pleural cavities. These data show that gammadelta T cell migration into the pleural cavity of mice during diverse inflammatory responses is dependent on LTB(4)/BLT1.

Endothelin-1 contributes to hemoglobin glutamer-200-mediated hepatocellular dysfunction after hemorrhagic shock

Hemoglobin glutamer-200 (HbG) might be an alternative to human blood. However, artificial oxygen carriers are initially successful to restore oxygen supply but may induce organ dysfunction and increase mortality several days after application in terms of delayed side effects. Impairment of microcirculation and an inflammatory cytokine response through induction of endothelin (ET) 1 may contribute. We investigated the role of HbG for the therapy of hemorrhagic shock and for delayed side effects in a model of hemorrhagic shock and reperfusion (H/R). To analyze early effects, Sprague-Dawley rats (n = 8/group) were resuscitated after hemorrhagic shock (1 h) with shed blood or HbG followed by reperfusion (2 h). Hemorrhagic shock and reperfusion decreased liver microcirculation and hepatic function in both shock groups to the same extent. Thus, HbG was not superior to shed blood regarding resuscitation end points after hemorrhagic shock. To determine delayed effects, rats (n = 8/group) were pretreated with Ringer's solution (vehicle) or HbG (1 g/kg) 24 h before H/R. Endothelin receptors were blocked with bosentan. Subsequently, ET-1 expression, inflammatory response, sinusoidal perfusion, hepatocellular function (plasma disappearance rate of indocyanine green [PDRICG]), and redox state [NAD(P)H] were analyzed. After vehicle pretreatment, H/R increased ET-1, hepatocellular injury, NAD(P)H, and cytokine levels. Sinusoidal perfusion and PDRICG decreased. After HbG pretreatment, a further increase of ET-1 and hepatocellular injury was observed, whereas PDRICG further decreased. Application of bosentan after HbG but not after vehicle pretreatment significantly improved PDRICG and liver perfusion, whereas NAD(P)H and hepatocellular injury decreased. Furthermore, cytokine release changed to an anti-inflammatory response. These data suggest an HbG-dependent increase of ET-1, which may contribute to delayed side effects under shock conditions.

Pulmonary exposure to soluble cell wall beta-(1, 3)-glucan of aspergillus induces proinflammatory response in mice

Compared to the significant immunomodulation of cell wall component(s) of bacterium such as lipopolysaccharide (E. Coli), that of pathogenic fungi has not been well elucidated, especially in vivo. Furthermore, although it has been implied that beta-(1, 3)-glucan of fungi possesses various biological activities, the impacts of the component have not been properly clarified, possibly due to its insolubility in water and alkali solutions. Previously, we isolated a soluble type of beta-(1, 3) -glucan from Aspergillus (referred to as ASBG). The present study investigated the effects of a single pulmonary exposure to ASBG on the immune (proinflammatory) responses in naïve mice. ASBG (12.5-100micorg/animal) exposure Induced neutrophilic lung inflammation with an enhanced local expression of proinflammatory cytokines such as interleukin (IL)-1beta and chemokines such as macrophage inflammatory protein -1a, and keratinocyte-derived chemoattractant in a dose-dependent fashion with overall trends. On the other hand, ASBG at relatively lower doses significantly amplified the lung expression of IL-2, IL-6, and IL-12 as compared with vehicle. ASBG significantly induced pulmonary edema. Furthermore, ASBG augmented the nuclear translocation of nuclear factor (NF)-kB and its binding capacity to the promoter site of DNA in the lung homogenate. These results suggest that pulmonary exposure to ASBG confers lung inflammation, at least partly, via the enhanced local expression of proinflammatory cytokines, likely through NF-kB-dependent pathway.

Candida soluble cell wall beta-glucan facilitates ovalbumin-induced allergic airway inflammation in mice: Possible role of antigen-presenting cells

BACKGROUND

Although fungi have been implicated as initiating/deteriorating factors for allergic asthma, their contributing components have not been fully elucidated. We previously isolated soluble beta-glucan from Candida albicans (CSBG) (Ohno et al., 2007). In the present study, the effects of CSBG exposure on airway immunopathology in the presence or absence of other immunogenic allergen was investigated in vivo, and their cellular mechanisms were analyzed both in vivo and in vitro.

METHODS

In vivo, ICR mice were divided into 4 experimental groups: vehicle, CSBG (25 microg/animal), ovalbumin (OVA: 2 microg/animal), and CSBG + OVA were repeatedly administered intratracheally. The bronchoalveolar lavage cellular profile, lung histology, levels of cytokines and chemokines in the lung homogenates, the expression pattern of antigen-presenting cell (APC)-related molecules in the lung digests, and serum immunoglobulin values were studied. In vitro, the impacts of CSBG (0-12.5 microg/ml) on the phenotype and function of immune cells such as splenocytes and bone marrow-derived dendritic cells (BMDCs) were evaluated in terms of cell proliferation, the surface expression of APC-related molecules, and OVA-mediated T-cell proliferating activity.

RESULTS

In vivo, repeated pulmonary exposure to CSBG induced neutrophilic airway inflammation in the absence of OVA, and markedly exacerbated OVA-related eosinophilic airway inflammation with mucus metaplasia in mice, which was concomitant with the amplified lung expression of Th2 cytokines and IL-17A and chemokines related to allergic response. Exposure to CSBG plus OVA increased the number of cells bearing MHC class II with or without CD80 in the lung compared to that of others. In vitro, CSBG significantly augmented splenocyte proliferation in the presence or absence of OVA. Further, CSBG increased the expression of APC-related molecules such as CD80, CD86, and DEC205 on BMDCs and amplified OVA-mediated T-cell proliferation through BMDCs.

CONCLUSION

CSBG potentiates allergic airway inflammation with maladaptive Th immunity, and this potentiation was associated with the enhanced activation of APCs including DC.

Impact of anti-inflammatory agents on the gene expression profile of stimulated human neutrophils: unraveling endogenous resolution pathways

Adenosine, prostaglandin E(2), or increased intracellular cyclic AMP concentration each elicit potent anti-inflammatory events in human neutrophils by inhibiting functions such as phagocytosis, superoxide production, adhesion and cytokine release. However, the endogenous molecular pathways mediating these actions are poorly understood. In the present study, we examined their impact on the gene expression profile of stimulated neutrophils. Purified blood neutrophils from healthy donors were stimulated with a cocktail of inflammatory agonists in the presence of at least one of the following anti-inflammatory agents: adenosine A(2A) receptor agonist CGS 21680, prostaglandin E(2), cyclic-AMP-elevating compounds forskolin and RO 20-1724. Total RNA was analyzed using gene chips and real-time PCR. Genes encoding transcription factors, enzymes and regulatory proteins, as well as secreted cytokines/chemokines showed differential expression. We identified 15 genes for which the anti-inflammatory agents altered mRNA levels. The agents affected the expression profile in remarkably similar fashion, suggesting a central mechanism limiting cell activation. We have identified a set of genes that may be part of important resolution pathways that interfere with cell activation. Identification of these pathways will improve understanding of the capacity of tissues to terminate inflammatory responses and contribute to the development of therapeutic strategies based on endogenous resolution.

BALB/c mice genetically susceptible to proteoglycan-induced arthritis and spondylitis show colony-dependent differences in disease penetrance

Introduction

The major histocompatibility complex (H-2d) and non-major histocompatibility complex genetic backgrounds make the BALB/c strain highly susceptible to inflammatory arthritis and spondylitis. Although different BALB/c colonies develop proteoglycan-induced arthritis and proteoglycan-induced spondylitis in response to immunization with human cartilage proteoglycan, they show significant differences in disease penetrance despite being maintained by the same vendor at either the same or a different location.

Methods

BALB/c female mice (24 to 26 weeks old after 4 weeks of acclimatization) were immunized with a suboptimal dose of cartilage proteoglycan to explore even minute differences among 11 subcolonies purchased from five different vendors. In vitro-measured T-cell responses, and serum cytokines and (auto)antibodies were correlated with arthritis (and spondylitis) phenotypic scores. cDNA microarrays were also performed using spleen cells of naïve and immunized BALB/cJ and BALB/cByJ mice (both colonies from The Jackson Laboratory, Bar Harbor, ME, USA), which represent the two major BALB/c sublines.

Results

The 11 BALB/c colonies could be separated into high (n = 3), average (n = 6), and low (n = 2) responder groups based upon their arthritis scores. While the clinical phenotypes showed significant differences, only a few immune parameters correlated with clinical or histopathological abnormalities, and seemingly none of them affected differences found in altered clinical phenotypes (onset time, severity or incidence of arthritis, or severity and progression of spondylitis). Affymetrix assay (Affymetrix, Santa Clara, CA, USA) explored 77 differentially expressed genes (at a significant level, P < 0.05) between The Jackson Laboratory's BALB/cJ (original) and BALB/cByJ (transferred from the National Institutes of Health, Bethesda, MD, USA). Fourteen of the 77 differentially expressed genes had unknown function; 24 of 77 genes showed over twofold differences, and only 8 genes were induced by immunization, some in both colonies.

Conclusions

Using different subcolonies of the BALB/c strain, we can detect significant differences in arthritis phenotypes, single-nucleotide polymorphisms (SNPs), and a large number of differentially expressed genes, even in non-immunized animals. A number of the known genes (and SNPs) are associated with immune responses and/or arthritis in this genetically arthritis-prone murine strain, and a number of genes of as-yet-unknown function may affect or modify clinical phenotypes of arthritis and/or spondylitis.

Targeting endothelin ETA and ETB receptors inhibits antigen-induced neutrophil migration and mechanical hypernociception in mice

Endothelin may contribute to the development of inflammatory events such as leukocyte recruitment and nociception. Herein, we investigated whether endothelin-mediated mechanical hypernociception (decreased nociceptive threshold, evaluated by electronic pressure-meter) and neutrophil migration (myeloperoxidase activity) are inter-dependent in antigen challenge-induced Th1-driven hind-paw inflammation. In antigen challenge-induced inflammation, endothelin (ET) ET(A) and ET(B) receptor antagonism inhibited both hypernociception and neutrophil migration. Interestingly, ET-1 peptide-induced hypernociception was not altered by inhibiting neutrophil migration or endothelin ET(B) receptor antagonism, but rather by endothelin ET(A) receptor antagonism. Furthermore, endothelin ET(A), but not ET(B), receptor antagonism inhibited antigen-induced PGE(2) production, whereas either selective or combined blockade of endothelin ET(A) and/or ET(B) receptors reduced hypernociception and neutrophil recruitment caused by antigen challenge. Concluding, this study advances knowledge into the role for endothelin in inflammatory mechanisms and further supports the potential of endothelin receptor antagonists in controlling inflammation.