Evaluating the antimicrobial and anti-biofilm activity of three synthetic antimicrobial Citropin analogs and their ability to fight against Staphylococcus aureus and Staphylococcus pseudintermedius.

AIMS: We developed three new analogs of the antimicrobial peptide (AMP) Citropin 1.1: DAN-1-13, AJP-1-1, and HHX-2-28, and tested their potential antimicrobial and antibiofilm activities against Staphylococcus aureus and S. pseudintermedius. Potential cytotoxic or hemolytic effects were determined using cultured human keratinocytes and erythrocytes to determine their safety. METHODS AND RESULTS: To assess the antimicrobial activity of each compound, minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) were determined against methicillin-resistant and methicillin-susceptible strains of S. aureus and S. pseudintermedius. Activity against newly formed and mature biofilms was determined in two clinical isolates using spectrophotometry and scanning electron microscopy (SEM). All three compounds exhibited antimicrobial and bactericidal activity against all studied S. aureus and S. pseudintermedius strains, with MICs ranging from 4-32 µg ml-1 and MBCs ranging from 8-128 µg ml-1. Subinhibitory concentrations of all compounds also showed ant-biofilm activity in the two tested isolates. All compounds exhibited limited cytotoxic and hemolytic activity. CONCLUSIONS: Novel analogs of Citropin 1.1 exhibit antimicrobial and bactericidal activities against S. aureus and S. pseudintermedius isolates and inhibit the biofilm formation of these bacteria.

Characterizing biofilm formation of Staphylococcus pseudintermedius in different suture materials.

Staphylococcus pseudintermedius is the primary cause of pyoderma and surgical site infection (SSI) in dogs, and biofilm formation is the main reason for persistent SSI. The presence of biofilm in medical devices can directly impact treatment. Methicillin-resistant S. pseudintermedius (MRSP) emerged rapidly in companion animals, limiting treatment options. MRSP is a public health problem since zoonotic transmission can occur. The study seeks to evaluate biofilm formation capacity via Staphylococcus pseudintermedius collected from dogs affected by topical infections, in suture materials commonly used in companion animal surgery. We tested segments of four types of sutures. Biofilm production was measured by staining with safranin and colorimetric absorbance measurement. We calculated colony-forming units (CFUs) for each type of sutures and visualized biofilm via Scanning Electron Microscopy (SEM) images. The genes associated with biofilm formation (icaA and icaD) were identified using PCR. The colorimetric tests showed that the biofilm is most abundantly formed on the cotton sutures and polyglactin 910. The ability to form biofilm on polypropylene and nylon sutures has also been demonstrated, although at varying intensities. PCR revealed the presence of the two genes (icaA and icaD) in all the isolates. We used a positive control using a reference strain and negative control without bacteria for comparisons. Suture material allowing biofilm formation makes it difficult to prevent and treat surgical site infections. Therefore, it is important to know which suture thread is more susceptible to biofilm formation by bacteria to prevent possible secondary infections at surgical sites.

Biological Response to Nanosurface Modification on Metallic Biomaterials.

PURPOSE OF REVIEW: New biomaterials for biomedical applications have been developed over the past few years. This work summarizes the current cell lines investigations regarding nanosurface modifications to improve biocompatibility and osseointegration. RECENT FINDINGS: Material surfaces presenting biomimetic morphology that provides nanoscale architectures have been shown to alter cell/biomaterial interactions. Topographical and biofunctional surface modifications present a positive effect between material and host response. Nanoscale surfaces on titanium have the potential to provide a successful interface for implantable biomedical devices. Future studies need to directly evaluate how the titanium nanoscale materials will perform in in vivo experiments. Biocompatibility should be determined to identify titanium nanoscale as an excellent option for implant procedures.

NLRP3 inflammasome-mediated neutrophil recruitment and hypernociception depend on leukotriene B(4) in a murine model of gout.

OBJECTIVE: Deposition of monosodium urate monohydrate (MSU) crystals in the joints promotes an intense inflammatory response and joint dysfunction. This study evaluated the role of the NLRP3 inflammasome and 5-lipoxygenase (5-LOX)-derived leukotriene B(4) (LTB(4) ) in driving tissue inflammation and hypernociception in a murine model of gout. METHODS: Gout was induced by injecting MSU crystals into the joints of mice. Wild-type mice and mice deficient in NLRP3, ASC, caspase 1, interleukin-1ß (IL-1ß), IL-1 receptor type I (IL-1RI), IL-18R, myeloid differentiation factor 88 (MyD88), or 5-LOX were used. Evaluations were performed to assess neutrophil influx, LTB(4) activity, cytokine (IL-1ß, CXCL1) production (by enzyme-linked immunosorbent assay), synovial microvasculature cell adhesion (by intravital microscopy), and hypernociception. Cleaved caspase 1 and production of reactive oxygen species (ROS) were analyzed in macrophages by Western blotting and fluorometric assay, respectively. RESULTS: Injection of MSU crystals into the knee joints of mice induced neutrophil influx and neutrophil-dependent hypernociception. MSU crystal-induced neutrophil influx was CXCR2-dependent and relied on the induction of CXCL1 in an NLRP3/ASC/caspase 1/IL-1ß/MyD88-dependent manner. LTB(4) was produced rapidly after injection of MSU crystals, and this was necessary for caspase 1-dependent IL-1ß production and consequent release of CXCR2-acting chemokines in vivo. In vitro, macrophages produced LTB(4) after MSU crystal injection, and LTB(4) was relevant in the MSU crystal-induced maturation of IL-1ß. Mechanistically, LTB(4) drove MSU crystal-induced production of ROS and ROS-dependent activation of the NLRP3 inflammasome. CONCLUSION: These results reveal the role of the NLRP3 inflammasome in mediating MSU crystal-induced inflammation and dysfunction of the joints, and highlight a previously unrecognized role of LTB(4) in driving NLRP3 inflammasome activation in response to MSU crystals, both in vitro and in vivo.

Morphine peripheral analgesia depends on activation of the PI3Kgamma/AKT/nNOS/NO/KATP signaling pathway.

Morphine is one of the most prescribed and effective drugs used for the treatment of acute and chronic pain conditions. In addition to its central effects, morphine can also produce peripheral analgesia. However, the mechanisms underlying this peripheral action of morphine have not yet been fully elucidated. Here, we show that the peripheral antinociceptive effect of morphine is lost in neuronal nitric-oxide synthase null mice and that morphine induces the production of nitric oxide in primary nociceptive neurons. The activation of the nitric-oxide pathway by morphine was dependent on an initial stimulation of PI3Kgamma/AKT protein kinase B (AKT) and culminated in increased activation of K(ATP) channels. In the latter, this intracellular signaling pathway might cause a hyperpolarization of nociceptive neurons, and it is fundamental for the direct blockade of inflammatory pain by morphine. This understanding offers new targets for analgesic drug development.

Anti-inflammatory effects of the activation of the angiotensin-(1-7) receptor, MAS, in experimental models of arthritis.

Activation of the renin-angiotensin (Ang) system induces inflammation via interaction between Ang II and type 1 receptor on leukocytes. The relevance of the new arm of the renin-Ang system, namely Ang-converting enzyme-2/Ang-(1-7)/Mas receptor, for inflammatory responses is not known and was investigated in this study. For this purpose, two experimental models were used: Ag-induced arthritis (AIA) in mice and adjuvant-induced arthritis (AdIA) in rats. Male C57BL/6 wild-type or Mas(-/-) mice were subjected to AIA and treated with Ang-(1-7), the Mas agonist AVE 0991, or vehicle. AdIA was performed in female rats that were given AVE 0991 or vehicle. In wild-type mice, Mas protein is expressed in arthritic joints. Administration of AVE 0991 or Ang-(1-7) decreased AIA-induced neutrophil accumulation, hypernociception, and production of TNF-α, IL-1ß, and CXCL1. Histopathological analysis showed significant reduction of inflammation. Mechanistically, AVE 0991 reduced leukocyte rolling and adhesion, even when given after Ag challenge. Mas(-/-) mice subjected to AIA developed slightly more pronounced inflammation, as observed by greater neutrophil accumulation and cytokine release. Administration of AVE 0991 was without effect in Mas(-/-) mice subjected to AIA. In rats, administration of AVE 0991 decreased edema, neutrophil accumulation, histopathological score, and production of IL-1ß and CXCL1 induced by AdIA. Therefore, activation of Mas receptors decreases neutrophil influx and cytokine production and causes significant amelioration of arthritis in experimental models of arthritis in rats and mice. This approach might represent a novel therapeutic opportunity for arthritis.

Essential role of platelet-activating factor receptor in the pathogenesis of Dengue virus infection.

Severe dengue infection in humans causes a disease characterized by thrombocytopenia, increased levels of cytokines, increased vascular permeability, hemorrhage, and shock. Treatment is supportive. Activation of platelet-activating factor (PAF) receptor (PAFR) on endothelial cells and leukocytes induces increase in vascular permeability, hypotension, and production of cytokines. We hypothesized that activation of PAFR could account for the major systemic manifestations of dengue infection. Inoculation of adult mice with an adapted strain of Dengue virus caused a systemic disease, with several features of the infection in humans. In PAFR(-/-) mice, there was decreased thrombocytopenia, hemoconcentration, decreased systemic levels of cytokines, and delay of lethality, when compared with WT infected mice. Treatment with UK-74,505, an orally active PAFR antagonist, prevented the above-mentioned manifestations, as well as hypotension and increased vascular permeability, and decreased lethality, even when started 5 days after virus inoculation. Similar results were obtained with a distinct PAFR antagonist, PCA-4246. Despite decreased disease manifestation, viral loads were similar (PAFR(-/-)) or lower (PAFR antagonist) than in WT mice. Thus, activation of PAFR plays a major role in the pathogenesis of experimental dengue infection, and its blockade prevents more severe disease manifestation after infection with no increase in systemic viral titers, suggesting that there is no interference in the ability of the murine host to deal with the infection. PAFR antagonists are disease-modifying agents in experimental dengue infection.

Polymeric Orthosis with Electromagnetic Stimulator Controlled by Mobile Application for Bone Fracture Healing: Evaluation of Design Concepts for Medical Use.

Background: The occurrence of bone fractures is increasing worldwide, mainly due to the health problems that follow the aging population. The use of additive manufacturing and electrical stimulators can be applied for bioactive achievements in bone healing. However, such technologies are difficult to be transferred to medical practice. This work aims to develop an orthosis with a combined magnetic field (CFM) electrostimulator that demonstrates concepts and design aspects that facilitate its use in a real scenario. Methods: A 3D-printed orthosis made of two meshes was manufactured using PLA for outer mechanical stabilization mesh and TPU for inner fixation mesh to avoid mobilization. A CFM stimulator of reduced dimension controlled by a mobile application was coupled onto the orthosis. The design concepts were evaluated by health professionals and their resistance to chemical agents commonly used in daily activities were tested. Their thermal, chemical and electrical properties were also characterized. Results: No degradation was observed after exposure to chemical agents. The CMF achieved proper intensity (20-40 µT). The thermal analysis indicated its appropriate use for being modelled during clinical assessment. Conclusion: An orthosis with a coupled electrostimulator that works with a combined magnetic field and is controlled by mobile application was developed, and it has advantageous characteristics when compared to traditional techniques for application in real medical environments.

Effects on the Properties of Self-Compacting Cement Paste (PAA) with the Addition of Superabsorbent Polymer.

The addition of Superabsorbent Polymer (SAP) decreases the effect of autogenous shrinkage present in pastes, mortars, and concretes. In this study we investigated the influence of the addition of SAP in self-compacting cement paste mixtures. Eighteen 5 × 10 cylindrical specimens were molded in all, three for each mixture (CPII base, CPII 0.15%SAP/600µm, CPII 0.15%SAP/800 µm, CPV base, CPV 0.15%SAP/600 µm, CPV 0.15%SAP/800 µm). Two types of cement were tested, CP II-Z and CP V-ARI with 0.15% of weight replaced per two diameters of SAP (600 µm and 800 µm). The samples followed the standards required. Mini slump tests were carried out in the fresh state, and uniaxial compressive strength, elastic modulus, specific mass, absorption, and air content in the hardened state after 28 days. The results obtained show the SAP is high indicated to replaced cement in small % of weight i/to fresh and hardened paste. Likewise, the group mix n° 3 composed of CPII 0.15% of SAP with 800 µm diameter presented the best result.

Coffea arabica extracts and their chemical constituents in a murine model of gouty arthritis: How they modulate pain and inflammation.

ETHNOPHARMACOLOGICAL RELEVANCE: Coffea arabica is commonly known for its cardiotonic and neurotonic activities, but in some places' folk medicine, like in Arabia and Africa, C. arabica is used to treat headache, migraine, the flu, anemia, oedema, asthenia, asthma, inflammation and wounds. AIMS OF THE STUDY: The aims were to evaluate if the aqueous extracts of Coffea arabica, prepared from beans with different degrees of roasting, and their main chemical constituents could exert an in vivo anti-gouty effect. MATERIALS AND METHODS: Coffea extracts were obtained from the beans of not roasted, light, medium and dark roasted coffee and from decaffeinated and traditional coffees and were prepared with water at 25°C and at 98°C. C57BL/6 mice were induced to gout by an injection of monosodium urate crystals and treated with coffee extracts at doses of 25, 75 and 225 mg/kg and their chemical constituents at a dose of 10 mg/kg. The antinociceptive and anti-inflammatory effects were evaluated. RESULTS: Treatments with Coffea extracts prepared with water at 98°C were more effective to exert antinociceptive and anti-inflammatory activities than the ones prepared with water at 25°C. Caffeic and chlorogenic acids reduced hypernociception in animals when compared with negative control group (7.79 and 5.69 vs 18.53; P < 0.05 and P < 0.001, respectively), inhibited neutrophil migration (1.59 × 104 and 0.38 × 104 vs 9.47 × 104; P < 0.0001 both) and decreased pro-inflammatory cytokines concentration (IL-1ß, IL-6 and TNF-α). CONCLUSIONS: We have demonstrated that our treatments attenuated gout, and this effect could be attributed to a reducement in hypernociception, neutrophil migration and cytokines concentration. These results suggest coffee as a potential candidate for studies in acute gout therapy.

'Hypericum brasiliense: bactericidal and antibiofilm activity against Staphylococcus aureus in vitro'.

Staphylococcus aureus is considered the most common opportunistic pathogen in humans, capable of forming biofilm, increasing the chances of antibiotic resistance and causes several chronic diseases. Biodiversity is a source of inspiration in the search for new agents against these microorganisms. Hitherto, the efficacy of Hypericum sp. extracts as an antibacterial agent has already been demonstrated against Gram-positive and Gram-negative bacteria. In this study, we observed that until 4 µg/mL, the Hypericum brasiliense extract showed bactericidal activity against a clinical multidrug-resistant S. aureus strain (HU25) and also inhibited biofilm formation at 1/2xMIC (confirmed by SEM) and 1/4xMIC. The extract was also proportionally active against 6 h-preformed biofilm to its concentration (1/2xMIC, 1/4xMIC, p value ≤ 0.05). These promising results make Hypericum brasiliense extract a strong candidate to treat S. aureus infections, including anti-biofilm therapy.

Teleantagonism: A pharmacodynamic property of the primary nociceptive neuron.

Previous work from our group showed that intrathecal (i.t.) administration of substances such as glutamate, NMDA, or PGE(2) induced sensitization of the primary nociceptive neuron (PNN hypernociception) that was inhibited by a distal intraplantar (i.pl.) injection of either morphine or dipyrone. This pharmacodynamic phenomenon is referred to in the present work as "teleantagonism". We previously observed that the antinociceptive effect of i.t. morphine could be blocked by injecting inhibitors of the NO signaling pathway in the paw (i.pl.), and this effect was used to explain the mechanism of opioid-induced peripheral analgesia by i.t. administration. The objective of the present investigation was to determine whether this teleantagonism phenomenon was specific to this biochemical pathway (NO) or was a general property of the PNNs. Teleantagonism was investigated by administering test substances to the two ends of the PNN (i.e., to distal and proximal terminals; i.pl. plus i.t. or i.t. plus i.pl. injections). We found teleantagonism when: (i) inhibitors of the NO signaling pathway were injected distally during the antinociception induced by opioid agonists; (ii) a nonselective COX inhibitor was tested against PNN sensitization by IL-1beta; (iii) selective opioid-receptor antagonists tested against antinociception induced by corresponding selective agonists. Although the dorsal root ganglion seems to be an important site for drug interactions, the teleantagonism phenomenon suggests that, in PNNs, a local sensitization spreads to the entire cell and constitutes an intriguing and not yet completely understood pharmacodynamic property of this group of neurons.

Sesquiterpene lactones from Lychnophora species: Antinociceptive, anti-inflammatory, and antioxidant pathways to treat acute gout.

ETHNOPHARMACOLOGICAL RELEVANCE: Lychnophora trichocarpha and Lychnophora passerina are species used in folk medicine to treat inflammation, pain, and rheumatism. Previous studies have demonstrated the anti-inflammatory effect of ethanol extracts of these species and identified that sesquiterpene lactones contribute to this activity. AIM OF THE STUDY: Gout is an acute inflammatory arthritis caused by the deposition of monosodium urate (MSU) crystals in joints. Inflammation in joints induces oxidative stress in defense cells, releasing pro-inflammatory mediators. This study has three objectives: (1) to demonstrate the effects of sesquiterpene lactones lychnopholide and eremantholide C isolated from L. trichocarpha and goyazensolide isolated from L. passerina on arthritis induced by MSU crystals in C57BL6 mice; (2) to determine whether or not these compounds can inhibit the migration of neutrophils and the release of TNF-α and IL-1ß cytokines in the inflammation region; and (3) to evaluate the effects of sesquiterpene lactones on the activities of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in the cartilage of C57BL/6 mice with gouty arthritis. MATERIALS AND METHODS: The anti-inflammatory, antinociceptive, and antioxidant activities of sesquiterpene lactones in C57BL/6 mice with MSU crystal-induced arthritis were evaluated. In our experimental model, the mice were injected with MSU crystals in the tibiofemoral joint to induce arthritis and then treated with indomethacin, vitamin C, and sesquiterpene lactones. Nociception was evaluated before and after inflammation induction and treatments, neutrophil migration, IL-1ß and TNF-α concentrations, and SOD and CAT activities. RESULTS: Sesquiterpene lactones exerted an anti-inflammatory effect by inhibiting neutrophil migration and TNF-α production. These compounds also demonstrated antinociceptive and antioxidant activities. CONCLUSION: Lychnopholide, eremantholide C, and goyazensolide improved the inflammation induced by MSU crystals by inhibiting the migration of neutrophils to the inflamed area and by blocking the release of the pro-inflammatory cytokine TNF-α. In addition, sesquiterpene lactones reduced oxidative stress by activating SOD and CAT. These results suggest that sesquiterpene lactones have anti-gout activity through the inflammation, pain, and oxidative stress pathways.

Lychnophora pinaster's effects on inflammation and pain in acute gout.

ETHNOPHARMACOLOGICAL RELEVANCE: Ethanolic extract of aerial parts from Lychnophora pinaster Mart. are used in traditional Brazilian medicine for treating pain, rheumatism and inflammation. AIM OF THE STUDY: Drugs for the treatment of gout present severe adverse effects, justifying the need to search for new therapeutic options. The aim of the present study was to evaluate the effects of the ethanolic extract of L. pinaster and its main constituents in arthritis induced in mice by the injection of monosodium urate (MSU) crystals. MATERIALS AND METHODS: Antinociceptive effect was investigated using an electronic pressure-meter nociception paw test in C57BL/6 mice. Anti-gouty arthritis was investigated in mice induced with gout by the injection of MSU crystals into their femur-tibial tissue. Ethanolic extract of the aerial parts of Lychnophora pinaster and its main chemical constituents were evaluated as treatment. RESULTS: The ethanolic extract and their main chemical constituents inhibited neutrophil migration, reduced IL-1ß and TNF-α concentrations in the inflamed tissue and showed antinociceptive activity. CONCLUSIONS: Gouty arthritis effects of the ethanolic extract can be attached to a synergistic effect of terpenes, flavonoids and phenolic acids present in the extract. Results obtained support the use of this extract and its main chemical constituents in the treatment of gout, inflammation, and pain.

Virulence Factors Found in Nasal Colonization and Infection of Methicillin-Resistant Staphylococcus aureus (MRSA) Isolates and Their Ability to Form a Biofilm.

Hospitalizations related to Methicillin-resistant Staphylococcus aureus (MRSA) are frequent, increasing mortality and health costs. In this way, this study aimed to compare the genotypic and phenotypic characteristics of MRSA isolates that colonize and infect patients seen at two hospitals in the city of Niterói-Rio de Janeiro, Brazil. A total of 147 samples collected between March 2013 and December 2015 were phenotyped and genotyped to identify the protein A (SPA) gene, the mec staphylococcal chromosomal cassette (SCCmec), mecA, Panton-Valentine Leucocidin (PVL), icaC, icaR, ACME, and hla virulence genes. The strength of biofilm formation has also been exploited. The prevalence of SCCmec type IV (77.1%) was observed in the colonization group; however, in the invasive infection group, SCCmec type II was prevalent (62.9%). The Multilocus Sequence Typing (MLST), ST5/ST30, and ST5/ST239 analyses were the most frequent clones in colonization, and invasive infection isolates, respectively. Among the isolates selected to assess the ability to form a biofilm, 51.06% were classified as strong biofilm builders. Surprisingly, we observed that isolates other than the Brazilian Epidemic Clone (BEC) have appeared in Brazilian hospitals. The virulence profile has changed among these isolates since the ACME type I and II genes were also identified in this collection.

Biological Evaluation of Selected 1,2,3-triazole Derivatives as Antibacterial and Antibiofilm Agents.

BACKGROUND: Resistance to antimicrobial agents is a major public health problem, being Staphylococcus aureus prevalent in infections in hospital and community environments and, admittedly, related to biofilm formation in biotic and abiotic surfaces. Biofilms form a complex and structured community of microorganisms surrounded by an extracellular matrix adhering to each other and to a surface that gives them even more protection from and resistance against the action of antimicrobial agents, as well as against host defenses. METHODS: Aiming to control and solve these problems, our study sought to evaluate the action of 1,2,3- triazoles against a Staphylococcus aureus isolate in planktonic and in the biofilm form, evaluating the activity of this triazole through Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) tests. We have also performed cytotoxic evaluation and Scanning Electron Microscopy (SEM) of the biofilms under the treatment of the compound. The 1,2,3-triazole DAN 49 showed bacteriostatic and bactericidal activity (MIC and MBC 128 µg/mL). In addition, its presence interfered with the biofilm formation stage (1/2 MIC, p <0.000001) and demonstrated an effect on young preformed biofilm (2 MICs, p <0.05). RESULTS: Scanning Electron Microscopy images showed a reduction in the cell population and the appearance of deformations on the surface of some bacteria in the biofilm under treatment with the compound. CONCLUSION: Therefore, it was possible to conclude the promising anti-biofilm potential of 1,2,3-triazole, demonstrating the importance of the synthesis of new compounds with biological activity.

The role of Na(V)1.8 sodium channel in the maintenance of chronic inflammatory hypernociception.

We previously described an animal model of persistent inflammatory sensitization of nociceptors. In this model the hypernociception persists for more than 30 days after the cessation of 2 weeks of daily intraplantar treatment with prostaglandin E(2) (PGE(2)). The tetrodotoxin-resistant (TTX-R) voltage-gated sodium channel Na(V)1.8 is considered a characteristic of primary afferent nociceptive C fibers and plays an important role in acute hypernociception. In the present study, the relevance of the Na(V)1.8 channel was investigated in this model of persistent mechanical hypernociception in rats. In the PGE(2)-induced persistent hypernociception, but not in the single injection-induced acute hypernociception, the mRNA expression (RT-PCR) of Na(V)1.8 in dorsal root ganglia (DRG) was up-regulated. A similar increase of Na(V)1.8 mRNA was observed when DbcAMP was used to induce persistent hypernociception. Four daily intrathecal administrations of oligodeoxynucleotides (ODN) antisense against Na(V)1.8 decreased the mRNA encoding Na(V)1.8 in DRG. The intrathecal administration of ODN antisense prevented the PGE(2)-induced acute hypernociception and significantly reduced ongoing PGE(2)-induced persistent hypernociception. A parallel restoration of the persistent hypernociception and up-regulation of Na(V)1.8 mRNA was observed after the cessation of ODN antisense treatment. These results suggest the participation of Na(V)1.8 channels in the development and maintenance of chronic inflammatory hyperalgesia, and confirm their involvement in the acute inflammatory hypernociception.

Lithothamnion muelleri treatment ameliorates inflammatory and hypernociceptive responses in antigen-induced arthritis in mice.

Rheumatoid Arthritis (RA) is a chronic disease characterized by persistent inflammation and pain. Alternative therapies to reduce these symptoms are needed. Marine algae are valuable sources of diverse bioactive compounds. Lithothamnion muelleri (Hapalidiaceae) is a marine algae with anti-inflammatory, antitumor, and immunomodulatory properties. Here, we investigated the potential anti-inflammatory and analgesic activities of L. muelleri in a murine model of antigen-induced arthritis (AIA) in mice. Our results demonstrate that treatment with L. muelleri prevented inflammation and hypernociception in arthritic mice. Mechanistically, the crude extract and the polysaccharide-rich fractions of L. muelleri may act impairing the production of the chemokines CXCL1 and CXCL2, and consequently inhibit neutrophil influx to the knee joint by dampening the adhesion step of leukocyte recruitment in the knee microvessels. Altogether our results suggest that treatment with L.muelleri has a potential therapeutic application in arthritis treatment.

Tumour necrosis factor-alpha, interleukin-1beta and interleukin-8 induce persistent mechanical nociceptor hypersensitivity.

It has been previously described that daily intraplantar (i.pl.) injections of prostaglandin E2 (PGE2) and dopamine in rats for 14 days cause the development of a persistent mechanical nociceptor hypersensitivity state lasting more than 30 days. Considering that during inflammation, the release of these hyperalgesic agents are mediated by cytokines, we investigated in the present study whether interleukin-1beta (IL-1beta), IL-8 and tumour necrosis factor-alpha (TNF-alpha) are able to induce persistent mechanical nociceptor hypersensitivity. Daily i.pl. administration of TNF-alpha, IL-1beta or IL-8 for 18 days led to persistent mechanical nociceptor hypersensitivity, which lasted at least 30 days after the cessation of treatment. The co-treatment of the animals with IL-1beta plus indomethacin, but not with atenolol, prevented the induction of persistent mechanical nociceptor hypersensitivity. The co-treatment of the animals with IL-8 plus atenolol, but not with indomethacin, prevented the induction of persistent mechanical nociceptor hypersensitivity. The daily co-treatment of TNF-alpha with either indomethacin or atenolol partially inhibited (+/-50%) the induction of persistent mechanical nociceptor hypersensitivity. However, the combined treatment with indomethacin plus atenolol abolished the induction of the persistent mechanical nociceptive hypersensitivity by TNF-alpha.A single injection of cytokines in the contralateral paws of the animals with persistent hypersensitivity caused only an acute nociceptive response. This observation, together with the demonstration of undetectable levels of immunoglobulins against TNF-alpha, IL-1beta or IL-8 in the sera of animals after the development of the persistent hypersensitivity induced by those cytokines, indicate that this event is not due to an ongoing immunological response against the cytokines. In conclusion, our results support the suggestion that IL-1beta- and IL-8-induced persistent mechanical nociceptor hypersensitivity results from the endogenous release of eicosanoids and sympathetic amines, respectively. However, TNF-alpha-induced mechanical nociceptor hypersensitivity results from the concomitant endogenous release of eicosanoids and sympathomimetic mediators.

The critical role of leukotriene B4 in antigen-induced mechanical hyperalgesia in immunised rats.

1. We investigated the mediators responsible for mechanical hypersensitivity induced by antigen challenge in rats immunised with ovalbumin (OVA). 2. Challenge with OVA (12.5-100 micro g, intraplantar) caused a dose- and time-dependent mechanical hypersensitivity, which peaked 3 h after, decreased thereafter and reached control levels 24 h later. 3. Levels of TNFalpha, IL-1beta and cytokine-induced neutrophil chemoattractant 1 (CINC-1) were increased in paw skin after antigen challenge. 4. OVA-evoked hypersensitivity was partially inhibited (about 51%) by pretreatment with anti-TNFalpha, IL-1beta and IL-8 sera or with IL-1 receptor antagonist (IL-1ra), but not anti-NGF serum. Pretreatment with thalidomide (45 mg kg(-1)) or pentoxifylline (100 mg kg(-1)) also partially inhibited the hypersensitivity at 1-3 h after challenge. 5. Pretreatment with indomethacin (5 mg kg(-1)) or atenolol (1 mg kg(-1)) reduced the OVA-induced hypersensitivity at 1 and 3 h, but not at 5 h after challenge, while the combination of B(1) and B(2) bradykinin receptor antagonists was ineffective over the same times. 6. Pretreatment with MK886 (5-lipoxygenase-activating protein inhibitor, 3 mg kg(-1)), CP 105696 (LTB(4) receptor antagonist; 3 mg kg(-1)) or dexamethasone (0.5 mg kg(-1)) inhibited the hypersensitivity from 1 to 5 h. Furthermore, LTB(4) levels were increased in the paw skin of challenged rats. 7. In conclusion, our results suggest that the TNFalpha-, IL-1beta- and CINC-1-driven release of prostaglandins, sympathetic amines and LTB(4) mediates the first 3 h of mechanical hypersensitivity induced by antigen challenge in rats. At 5 h after OVA administration, although TNFalpha has some role, LTB(4) is the critical nociceptive mediator.