Circulating Nestin-GFP+ Cells Participate in the Pathogenesis of Paracoccidioides brasiliensis in the Lungs.

Multiple infectious diseases lead to impaired lung function. Revealing the cellular mechanisms involved in this impairment is crucial for the understanding of how the lungs shift from a physiologic to a pathologic state in each specific condition. In this context, we explored the pathogenesis of Paracoccidioidomycosis, which affects pulmonary functioning. The presence of cells expressing Nestin-GFP has been reported in different tissues, and their roles as tissue-specific progenitors have been stablished in particular organs. Here, we explored how Nestin-GFP+ cells are affected after lung infection by Paracoccidioides brasiliensis, a model of lung granulomatous inflammation with fibrotic outcome. We used Nestin-GFP transgenic mice, parabiosis surgery, confocal microscopy and flow cytometry to investigate the participation of Nestin-GFP+ cells in Paracoccidioides brasiliensis pathogenesis. We revealed that these cells increase in the lungs post-Paracoccidioides brasiliensis infection, accumulating around granulomas. This increase was due mainly to Nestin-GPF+ cells derived from the blood circulation, not associated to blood vessels, that co-express markers suggestive of hematopoietic cells (Sca-1, CD45 and CXCR4). Therefore, our findings suggest that circulating Nestin-GFP+ cells participate in the Paracoccidioides brasiliensis pathogenesis in the lungs.

Animal model of arthritis and myositis induced by the Mayaro virus.

BACKGROUND: The Mayaro virus (MAYV) is an endemic arbovirus in South American countries, where it is responsible for sporadic outbreaks of Mayaro fever. Clinical manifestations include fever, headache, ocular pain, rash, myalgia, and debilitating and persistent polyarthralgia. Understanding the mechanisms associated with MAYV-induced arthritis is of great importance due to the potential for its emergence, urbanization and dispersion to other regions. METHODS: 15-day old Balb/c mice were infected by two distinct pathways, below the forelimb and in the rear footpad. Animals were observed for a period of 21 days. During this time, they were monitored every 24 hours for disease signs, such as weight loss and muscle weakness. Histological damage in the muscles and joints was evaluated 3, 7, 10, 15 and 20 days post-infection. The cytokine profile in serum and muscles during MAYV infection was evaluated by flow cytometry at different post-infection times. For pain analysis, the animals were submitted to the von Frey test and titre in different organs was evaluated throughout the study to obtain viral kinetics. FINDINGS: Infection by two distinct pathways, below the forelimb and in the rear footpad, resulted in a homogeneous viral spread and the development of acute disease in animals. Clinical signs were observed such as ruffled fur, hunched posture, eye irritation and slight gait alteration. In the physical test, both groups presented loss of resistance, which was associated with histopathological damage, including myositis, arthritis, tenosynovitis and periostitis. The immune response was characterized by a strong inflammatory response mediated by the cytokines TNF-α, IL-6 and INF-γ and chemokine MCP-1, followed by the action of IL-10 and IL-4 cytokines. INTERPRETATION: The results showed that Balb/c mice represent a promising model to study mechanisms involved in MAYV pathogenesis and for future antiviral testing.

In-depth characterization of congenital Zika syndrome in immunocompetent mice: Antibody-dependent enhancement and an antiviral peptide therapy.

BACKGROUND: Zika virus (ZIKV) infection during pregnancy may cause major congenital defects, including microcephaly, ocular, articular and muscle abnormalities, which are collectively defined as Congenital Zika Syndrome. Here, we performed an in-depth characterization of the effects of congenital ZIKV infection (CZI) in immunocompetent mice. METHODS: Pregnant dams were inoculated with ZIKV on embryonic day 5.5 in the presence or absence of a sub-neutralizing dose of a pan-flavivirus monoclonal antibody (4G2) to evaluate the potential role of antibody-dependent enhancement phenomenon (ADE) during short and long outcomes of CZI. FINDINGS: ZIKV infection induced maternal immune activation (MIA), which was associated with occurrence of foetal abnormalities and death. Therapeutic administration of AH-D antiviral peptide during the early stages of pregnancy prevented ZIKV replication and death of offspring. In the post-natal period, CZI was associated with a decrease in whole brain volume, ophthalmologic abnormalities, changes in testicular morphology, and disruption in bone microarchitecture. Some alterations were enhanced in the presence of 4G2 antibody. INTERPRETATION: Our results reveal that early maternal ZIKV infection causes several birth defects in immunocompetent mice, which can be potentiated by ADE phenomenon and are associated with MIA. Additionally, antiviral treatment with AH-D peptide may be beneficial during early maternal ZIKV infection. FUND: This work was supported by the Brazilian National Science Council (CNPq, Brazil), Minas Gerais Foundation for Science (FAPEMIG), Funding Authority for Studies and Projects (FINEP), Coordination of Superior Level Staff Improvement (CAPES), National Research Foundation of Singapore and Centre for Precision Biology at Nanyang Technological University.

Therapeutic treatment of Zika virus infection using a brain-penetrating antiviral peptide.

Zika virus is a mosquito-borne virus that is associated with neurodegenerative diseases, including Guillain-Barré syndrome1 and congenital Zika syndrome2. As Zika virus targets the nervous system, there is an urgent need to develop therapeutic strategies that inhibit Zika virus infection in the brain. Here, we have engineered a brain-penetrating peptide that works against Zika virus and other mosquito-borne viruses. We evaluated the therapeutic efficacy of the peptide in a lethal Zika virus mouse model exhibiting systemic and brain infection. Therapeutic treatment protected against mortality and markedly reduced clinical symptoms, viral loads and neuroinflammation, as well as mitigated microgliosis, neurodegeneration and brain damage. In addition to controlling systemic infection, the peptide crossed the blood-brain barrier to reduce viral loads in the brain and protected against Zika-virus-induced blood-brain barrier injury. Our findings demonstrate how engineering strategies can be applied to develop peptide therapeutics and support the potential of a brain-penetrating peptide to treat neurotropic viral infections.

Treatment with Atorvastatin Provides Additional Benefits to Imipenem in a Model of Gram-Negative Pneumonia Induced by Klebsiella pneumoniae in Mice.

The clinical pathogen Klebsiella pneumoniae is a relevant cause of nosocomial infections, and resistance to current treatment with carbapenem antibiotics is becoming a significant problem. Statins are inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) used for controlling plasma cholesterol levels. There is clinical evidence showing other effects of statins, including decrease of lung inflammation. In the current study, we show that pretreatment with atorvastatin markedly attenuated lung injury, which was correlated with a reduction in the cellular influx into the alveolar space and lungs and downmodulation of the production of proinflammatory mediators in the initial phase of infection in C57BL/6 mice with K. pneumoniae However, atorvastatin did not alter the number of bacteria in the lungs and blood of infected mice, despite decreasing local inflammatory response. Interestingly, mice that received combined treatment with atorvastatin and imipenem displayed better survival than mice treated with vehicle, atorvastatin, or imipenem alone. These findings suggest that atorvastatin could be an adjuvant in host-directed therapies for multidrug-resistant K. pneumoniae, based on its powerful pleiotropic immunomodulatory effects. Together with antimicrobial approaches, combination therapy with anti-inflammatory compounds could improve the efficiency of therapy during acute lung infections.

Zika Virus Promotes Neuronal Cell Death in a Non-Cell Autonomous Manner by Triggering the Release of Neurotoxic Factors.

Zika virus (ZIKV) has recently caused a worldwide outbreak of infections associated with severe neurological complications, including microcephaly in infants born from infected mothers. ZIKV exhibits high neurotropism and promotes neuroinflammation and neuronal cell death. We have recently demonstrated that N-methyl-d-aspartate receptor (NMDAR) blockade by memantine prevents ZIKV-induced neuronal cell death. Here, we show that ZIKV induces apoptosis in a non-cell autonomous manner, triggering cell death of uninfected neurons by releasing cytotoxic factors. Neuronal cultures infected with ZIKV exhibit increased levels of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), and glutamate. Moreover, infected neurons exhibit increased expression of GluN2B and augmented intracellular Ca2+ concentration. Blockade of GluN2B-containing NMDAR by ifenprodil normalizes Ca2+ levels and rescues neuronal cell death. Notably, TNF-α and IL-1ß blockade decreases ZIKV-induced Ca2+ flux through GluN2B-containing NMDARs and reduces neuronal cell death, indicating that these cytokines might contribute to NMDAR sensitization and neurotoxicity. In addition, ZIKV-infected cultures treated with ifenprodil exhibits increased activation of the neuroprotective pathway including extracellular signal-regulated kinase and cAMP response element-binding protein, which may underlie ifenprodil-mediated neuroprotection. Together, our data shed some light on the neurotoxic mechanisms triggered by ZIKV and begin to elucidate how GluN2B-containing NMDAR blockade can prevent neurotoxicity.

In Vitro TNF-α Inhibitory Activity of Brazilian Plants and Anti-Inflammatory Effect of Stryphnodendron adstringens in an Acute Arthritis Model.

Stryphnodendron species, popularly named "barbatimão," are traditionally used in Brazil as anti-inflammatory agents. This study aimed to investigate the effect of barbatimão and 11 other species on the production of tumor necrosis factor-alpha (TNF-α) in lipopolysaccharide- (LPS-) stimulated THP-1 cells, as well as their anti-arthritis activity. The extracts of Stryphnodendron adstringens, Stryphnodendron obovatum, Campomanesia lineatifolia, and Terminalia glabrescens promoted a concentration-dependent inhibition of TNF-α. Mice injected with LPS in the knee joint were treated per os with fractions from the selected extracts. Both the organic (SAO) and the aqueous (SAA) fractions of S. adstringens promoted a dose-dependent reduction of leukocyte migration and neutrophil accumulation into the joint, but none of them reduced CXCL1 concentration in the periarticular tissue. In contrast, treatment with C. lineatifolia and T. glabrescens fractions did not ameliorate the inflammatory parameters. Analyses of SAO by Ultra Performance Liquid Chromatography (UPLC) coupled to electrospray ionization mass spectrometry (ESI-MS) led to the identification of gallic acid along with 11 prodelphinidins, characterized as monomers and dimers of the B-type. Our findings contribute to some extent to corroborating the traditional use of S. adstringens as an anti-inflammatory agent. This activity is probably related to a decrease of leukocyte migration into the inflammatory site. Polyphenols like gallic acid and prodelphinidins, identified in the active fraction, may contribute to the observed activity.

The absence of microbiota delays the inflammatory response to Cryptococcus gattii.

The inflammatory response plays a crucial role in infectious diseases, and the intestinal microbiota is linked to maturation of the immune system. However, the association between microbiota and the response against fungal infections has not been elucidated. Our aim was to evaluate the influence of microbiota on Cryptococcus gattii infection. Germ-free (GF), conventional (CV), conventionalized (CVN-mice that received feces from conventional animals), and LPS-stimulated mice were infected with C. gattii. GF mice were more susceptible to infection, showing lower survival, higher fungal burden in the lungs and brain, increased behavioral changes, reduced levels of IFN-γ, IL-1ß and IL-17, and lower NFκBp65 phosphorylation compared to CV mice. Low expression of inflammatory cytokines was associated with smaller yeast cells and polysaccharide capsules (the main virulence factor of C. gattii) in the lungs, and less tissue damage. Furthermore, macrophages from GF mice showed reduced ability to engulf, produce ROS, and kill C. gattii. Restoration of microbiota (CVN mice) or LPS administration made GF mice more responsive to infection, which was associated with increased survival and higher levels of inflammatory mediators. This study is the first to demonstrate the influence of microbiota in the host response against C. gattii.

Histologic and inflammatory lamellar changes in horses with oligofructose-induced laminitis treated with a CXCR1/2 antagonist / Alterações histológicas e inflamatórias no tecido laminar de equinos submetidos ao modelo de laminite por oligofrutose e tratados com um antagonista para CXCR1/2

With the hypothesis that blocking chemokine signaling can ameliorate acute laminitis, the aim was to evaluate the therapeutic effect of intravenous DF1681B, a selective antagonist for CXCR1 and CXCR2 (chemokine receptors), in an oligofructose equine laminitis model. To twelve mixed breed clinically healthy hoses with no previous history of hoof-related lameness was administered oligofructose (10g/kg given by nasogastric tube) and divided into two groups: treated (intravenous DF1681B at 30mg/kg 6, 12, 18, and 24h after oligofructose) and non-treated groups. Laminar biopsies were performed before and 12, 36, and 72h after administering oligofructose. Samples were stained with periodic acid-Schiff (PAS) and scored from 0 to 6 according to epidermal cell and basal membrane changes. The IL-1β, IL-6, and CXCL1 RNA expressions were determined by RT-PCR. Parametric and non-parametric tests were used to compare times within each group (P<0.05). The PAS grades and IL-1β and IL-6 RNA expression increased in the non-treated group, but remained constant in the treated horses. In conclusion, DF1681B therapy reduced laminar inflammation and epidermal deterioration in treated horses. CXCR1/2 blockage should be considered therapeutically for equine acute laminitis.

A expressão de quimiocinas e a infiltração de leucócitos no tecido laminar são característicos de laminite aguda de equinos. O presente estudo avaliou o efeito terapêutico da administração intravenosa de DF1681B , um antagonista seletivo para CXCR1 e CXCR2 (receptores de quimiocinas), em um modelo de laminite equina por oligofrutose. Utilizaram-se doze cavalos sem raça definida, compreendendo quatro machos e oito fêmeas não gestantes, com idade (média ±SD) 7±3,5 anos, pesando 305±35kg e com uma pontuação média de condição corporal de 5±1/9. Os indivíduos elegíveis eram clinicamente saudáveis, sem história prévia de claudicação relacionados ao casco. Após administração de oligofrutose (10g/kg por sonda nasogástrica), os animais foram divididos em dois grupos: tratado (30mg/kg de DF1681B intravenosa, 6, 12, 18 e 24h após a oligofrutose) e não tratado, que recebeu placebo. Biópsias laminares foram realizadas antes e 12, 36 e 72h após a administração de oligofrutose. As amostras foram coradas com ácido periódico de Schiff (PAS) e classificadas de 0-6 de acordo com alterações nas células epidérmicas e na membrana basal. Também determinaram-se as expressões gênicas de IL-1β, CXCL1 e IL-6 por RT-PCR. Testes paramétricos e não paramétricos foram utilizados para comparar os momentos em cada grupo (P<0,05). Estatisticamente, os graus PAS e as expressões de IL-1β e IL-6 se elevaram após a indução no grupo não tratado, mas se mantiveram constantes nos cavalos tratados. Em conclusão, a terapia por DF1681B reduziu a inflamação laminar e a deterioração epidérmica em equinos submetidos ao modelo de intoxicação por oligofructose. O bloqueio de receptores CXCR1/2 deve ser considerado como uma opção terapêutica para prevenção da laminite aguda de equinos.

Transmembrane TNF-α is sufficient for articular inflammation and hypernociception in a mouse model of gout.

Gout manifests as recurrent episodes of acute joint inflammation and pain due to the deposition of monosodium urate (MSU) crystals within the affected tissue in a process dependent on NLRP3 inflammasome activation. The synthesis, activation, and release of IL-1ß are crucial for MSU-induced inflammation. The current study evaluated the mechanism by which TNF-α contributed to MSU-induced inflammation. Male C57BL/6J or transgenic mice were used in this study and inflammation was induced by the injection of MSU crystals into the joint. TNF-α was markedly increased in the joint after the injection of MSU. There was inhibition in the infiltration of neutrophils, production of CXCL1 and IL-1ß, and decreased hypernociception in mice deficient for TNF-α or its receptors. Pharmacological blockade of TNF-α with Etanercept or pentoxyfylline produced similar results. Mechanistically, TNF-α blockade resulted in lower amounts of IL-1ß protein and pro-IL-1ß mRNA transcripts in joints. Gene-modified mice that express only transmembrane TNF-α had an inflammatory response similar to that of WT mice and blockade of soluble TNF-α (XPro™1595) did not decrease MSU-induced inflammation. In conclusion, TNF-α drives expression of pro-IL-1ß mRNA and IL-1ß protein in experimental gout and that its transmembrane form is sufficient to trigger MSU-induced inflammation in mice.

Evaluation of the Wound Healing Properties of Hancornia speciosa Leaves.

The leaves of Hancornia speciosa Gomes (Apocynaceae), a medicinal species found in the Brazilian cerrado biome, are traditionally used to treat wounds and inflammatory disorders. The goal of the present study was to investigate the in vitro wound healing properties of ethanolic extract of H. speciosa leaves and its isolated compounds, using the scratch assay, and to evaluate their effects on the release of the pro-inflammatory cytokine tumor necrosis factor (TNF-α) by lipopolysaccharide (LPS)-stimulated human acute monocytic (THP-1) cells. H. speciosa ethanolic extract significantly increased (42.8% ± 5.4 at 25 µg/mL) cell migration and proliferation of fibroblasts compared with control cells, as well as the isolated compounds bornesitol (80.8% ± 5.1) and quinic acid (69.1% ± 6.2), both assayed at 50 µM. TNF-α release by LPS-stimulated THP-1 cells was significantly reduced by the ethanolic extract (62.9% ± 8.2, i.e. 1791.1 ± 394.7 pg/mL) at 10 µg/mL, bornesitol (48.9% ± 0.9, i.e. 2461.6 ± 43.1 pg/mL) at 50 µM, and quinic acid (90.2% ± 3.4, i.e. 473.5 ± 164.4 pg/mL) and rutin (82.4% ± 5.6, i.e. 847.0 ± 271.8 pg/mL) at 10 µM. These results provided evidences to support the traditional use of H. speciosa leaves to treat wounds and inflammatory disorders.

Dengue virus requires the CC-chemokine receptor CCR5 for replication and infection development.

Dengue is a mosquito-borne disease that affects millions of people worldwide yearly. Currently, there is no vaccine or specific treatment available. Further investigation on dengue pathogenesis is required to better understand the disease and to identify potential therapeutic targets. The chemokine system has been implicated in dengue pathogenesis, although the specific role of chemokines and their receptors remains elusive. Here we describe the role of the CC-chemokine receptor CCR5 in Dengue virus (DENV-2) infection. In vitro experiments showed that CCR5 is a host factor required for DENV-2 replication in human and mouse macrophages. DENV-2 infection induces the expression of CCR5 ligands. Incubation with an antagonist prevents CCR5 activation and reduces DENV-2 positive-stranded (+) RNA inside macrophages. Using an immunocompetent mouse model of DENV-2 infection we found that CCR5(-/-) mice were resistant to lethal infection, presenting at least 100-fold reduction of viral load in target organs and significant reduction in disease severity. This phenotype was reproduced in wild-type mice treated with CCR5-blocking compounds. Therefore, CCR5 is a host factor required for DENV-2 replication and disease development. Targeting CCR5 might represent a therapeutic strategy for dengue fever. These data bring new insights on the association between viral infections and the chemokine receptor CCR5.

Nanocomposite treatment reduces disease and lethality in a murine model of acute graft-versus-host disease and preserves anti-tumor effects.

Graft versus host disease (GVHD) is an immunological disorder triggered by bone marrow transplantation that affects several organs, including the gastrointestinal tract and liver. Fullerenes and their soluble forms, fullerols, are nanocomposites with a closed symmetrical structure with anti-inflammatory and anti-oxidant properties. The present study evaluated the effects of treatment with the fullerol (C60(OH)18-20) in the development and pathogenesis of GVHD in a murine model. Mice with experimental GVHD that were treated with the fullerol showed reduced clinical signs of disease and mortality compared with untreated mice. Treatment with the fullerol decreased the hepatic damage associated with reduced hepatic levels of reactive oxygen species, pro-inflammatory cytokines and chemokines (IFN-γ TNF-α, CCL2, CCL3 and CCL5) and reduced leukocyte accumulation. The amelioration of GVHD after treatment with the fullerol was also associated with reduced intestinal lesions and consequent bacterial translocation to the blood, liver and peritoneal cavity. Moreover, the fullerol treatment alleviated the GVHD while preserving effects of the graft against a leukemia cell line (GFP+P815). In summary, the fullerol was effective in reducing the GVHD inflammatory response in mice and may suggest novel ways to treat this disease.

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.

Fluconazole alters the polysaccharide capsule of Cryptococcus gattii and leads to distinct behaviors in murine Cryptococcosis.

Cryptococcus gattii is an emergent human pathogen. Fluconazole is commonly used for treatment of cryptococcosis, but the emergence of less susceptible strains to this azole is a global problem and also the data regarding fluconazole-resistant cryptococcosis are scarce. We evaluate the influence of fluconazole on murine cryptococcosis and whether this azole alters the polysaccharide (PS) from cryptococcal cells. L27/01 strain of C. gattii was cultivated in high fluconazole concentrations and developed decreased drug susceptibility. This phenotype was named L27/01F, that was less virulent than L27/01 in mice. The physical, structural and electrophoretic properties of the PS capsule of L27/01F were altered by fluconazole. L27/01F presented lower antiphagocytic properties and reduced survival inside macrophages. The L27/01F did not affect the central nervous system, while the effect in brain caused by L27/01 strain began after only 12 hours. Mice infected with L27/01F presented lower production of the pro-inflammatory cytokines, with increased cellular recruitment in the lungs and severe pulmonary disease. The behavioral alterations were affected by L27/01, but no effects were detected after infection with L27/01F. Our results suggest that stress to fluconazole alters the capsule of C. gattii and influences the clinical manifestations of cryptococcosis.

Inflammasome activation is reactive oxygen species dependent and mediates irinotecan-induced mucositis through IL-1ß and IL-18 in mice.

Irinotecan is a useful chemotherapeutic for the treatment of various cancers. Irinotecan treatment is associated with mucositis, which clearly limits the use of the drug. Mechanisms that account for mucositis are only partially known. This study assessed mechanisms and the role of inflammasome activation in irinotecan-induced mucositis. Mucositis in mice was induced by irinotecan injection in C57BL/6 wild-type, gp91phox(-/-), il-18(-/-), casp-1(-/-), and asc(-/-) mice once a day for 4 consecutive days. In some experiments, mice received apocynin to inhibit NADPH oxidase (NOX), IL-1 receptor antagonist, or IL-18 binding protein to prevent activation of IL-1 and IL-18 receptors, respectively. Mice were euthanized 7 days after the beginning of irinotecan treatment, and small intestines were collected for analysis. Irinotecan treatment resulted in increased IL-1ß and IL-18 production in ileum and NOX-2-dependent oxidative stress. gp91phox(-/-) and apocynin-treated mice had diminished oxidative stress and less severe mucositis. Furthermore, treatment with apocynin decreased caspase-1 activation and IL-1ß and IL-18 production in the ileum. asc(-/-) and casp-1(-/-) mice also had less intestinal injury and decreased IL-1ß and IL-18 production. Finally, both the absence of IL-18 and IL-1ß resulted in reduced inflammatory response and attenuated intestinal injury. NOX-2-derived oxidative stress mediates inflammasome activation and inflammasome-dependent production of IL-1ß and IL-18, which mediate tissue injury during irinotecan-induced mucositis in mice.

Role of the aryl hydrocarbon receptor in the immune response profile and development of pathology during Plasmodium berghei Anka infection.

Infection with Plasmodium falciparum may result in severe disease affecting various organs, including liver, spleen, and brain, resulting in high morbidity and mortality. Plasmodium berghei Anka infection of mice recapitulates many features of severe human malaria. The aryl hydrocarbon receptor (AhR) is an intracellular receptor activated by ligands important in the modulation of the inflammatory response. We found that AhR-knockout (KO) mice infected with P. berghei Anka displayed increased parasitemia, earlier mortality, enhanced leukocyte-endothelial cell interactions in the brain microvasculature, and increased inflammation in brain (interleukin-17 [IL-17] and IL-6) and liver (gamma interferon [IFN-γ] and tumor necrosis factor alpha [TNF-α]) compared to infected wild-type (WT) mice. Infected AhR-KO mice also displayed a reduction in cytokines required for host resistance, including TNF-α, IL-1ß, and IFN-γ, in the brain and spleen. Infection of AhR-KO mice resulted in an increase in T regulatory cells and transforming growth factor ß, IL-6, and IL-17 in the brain. AhR modulated the basal expression of SOCS3 in spleen and brain, and P. berghei Anka infection resulted in enhanced expression of SOCS3 in brain, which was absent in infected AhR-KO mice. These data suggest that AhR-mediated control of SOCS3 expression is probably involved in the phenotype seen in infected AhR-KO mice. This is, to our knowledge, the first demonstration of a role for AhR in the pathogenesis of malaria.

Anti-inflammatory and antinociceptive activities of azadirachtin in mice.

Azadirachta indica (Meliaceae) extracts have been reported to exhibit anti-inflammatory and antinociceptive properties. However, the activities of azadirachtin, a limonoid and the major bioactive compound found in the extracts, have been poorly investigated in animal models. In the present study, we investigated the effects induced by azadirachtin in experimental models of pain and inflammation in mice. Carrageenan-induced paw edema and fibrovascular tissue growth induced by subcutaneous cotton pellet implantation were used to investigate the anti-inflammatory activity of azadirachtin in mice. Zymosan-induced writhing and hot plate tests were employed to evaluate the antinociceptive activity. To explore putative mechanisms of action, the level of tumor necrosis factor-α in inflammatory tissue was measured and the effect induced by opioidergic and serotonergic antagonists was evaluated. Previous per os (p. o.) administration of azadirachtin (120 mg/kg) significantly reduced the acute paw edema induced by carrageenan. However, the concomitant increase of the paw concentration of tumor necrosis factor-α induced by this inflammatory stimulus was not reduced by azadirachtin. In addition to inhibiting the acute paw edema induced by carrageenan, azadirachtin (6, 60, and 120 mg/kg) inhibited the proliferative phase of the inflammatory response, as demonstrated by the reduced formation of fibrovascular tissue growth. Azadirachtin (120 mg/kg) also inhibited the nociceptive response in models of nociceptive (hot plate) and inflammatory (writhing induced by zymosan) pain. The activity of azadirachtin (120 mg/kg) in the model of nociceptive pain was attenuated by a nonselective opioid antagonist, naltrexone (10 mg/kg, i. p.), but not by a nonselective serotonergic antagonist, cyproheptadine. In conclusion, this study demonstrates the activity of azadirachtin in experimental models of nociceptive and inflammatory pain, and also in models of acute and chronic inflammation. Finally, multiple mechanisms, including the inhibition of the production of inflammatory mediators and activation of endogenous opioid pathways, may mediate azadirachtin activities in experimental models of inflammation and pain.

Lack of platelet-activating factor receptor protects mice against diet-induced adipose inflammation and insulin-resistance despite fat pad expansion.

OBJECTIVE: The role of platelet-activating factor (PAF) on diet-induced inflammatory and metabolic dysfunction is unknown. The effects of diet-induced metabolic and inflammatory dysfunction in mice with deletion of the PAF receptor (PAFR(-/-) ) were evaluated in this study. METHODS: Wild-type and PAFR(-/-) mice were fed chow (WT-C and PAFR(-/-) -C) or high-refined carbohydrate-containing diet (WT-HC and PAFR(-/-) -HC). PAFR(-/-) - RESULTS: HC mice gained more weight and adiposity than PAFR(-/-) -C and WT-HC mice. Lipogenesis increased and hormone-sensitive lipase expression decreased in PAFR(-/-) -HC compared to WT-HC mice. WT-HC mice had impaired glucose tolerance and insulin sensitivity compared to WT-C mice. In contrast, glucose tolerance and insulin sensitivity in PAFR(-/-) -HC mice were similar to that of lean littermates. PAFR(-/-) -HC mice expressed significantly more peroxisome proliferator-activator receptor gamma (PPARγ) than PAFR(-/-) -C and WT-C mice. Resistin increased in WT-HC mice compared to WT-C mice. However, the levels of resistin were 35% lower in PAFR(-/-) -HC mice than WT-HC mice. PAFR(-/-) presented with less HC diet-induced adipose tissue inflammation than WT mice. Adipocytes isolated from PAFR(-/-) mice incubated in media containing normal or high levels of glucose secreted less interleukin-6 and tumor necrosis factor alpha and presented lower rate of lipolysis than WT mice. CONCLUSION: PAFR deficiency resulted in less inflammation in adipose tissue and improvement in glucose homeostasis when fed the HC diet. The higher adiposity observed in PAFR(-/-) mice fed HC diet could be owing to the maintenance of insulin sensitivity, decreased adipocyte lipolysis rate, high lipogenesis and PPARγ expression, and lower inflammatory milieu in adipose tissue.

Preventive and therapeutic anti-TNF-α therapy with pentoxifylline decreases arthritis and the associated periodontal co-morbidity in mice.

AIMS: The association between rheumatoid arthritis (RA) and periodontal disease (PD) has long been studied and some reports suggest that treating RA may improve the associated PD, and vice versa. This study aimed to evaluate the effects of an anti-tumor necrosis factor (TNF)-α therapy with pentoxifylline (PTX) in an experimental model of RA-associated PD. MAIN METHODS: Male C57BL/6 mice were subjected to chronic antigen-induced arthritis (AIA) and daily treated with PTX (50mg/kg, i.p.) using preventive (Pre-PTX) or therapeutic (The-PTX) strategies. Fourteen days after the antigen challenge, mice were euthanized and knee joints, maxillae and serum were collected for microscopic and/or immunoenzymatic analysis. KEY FINDINGS: AIA triggered significant leukocyte recruitment to the synovial cavity, tissue damage and proteoglycan loss in the knee joint. Pre-PTX and The-PTX regimens decreased these signs of joint inflammation. The increased levels of TNF-α and IL-17 in periarticular tissues of AIA mice were also reduced by both PTX treatments. Serum levels of C-reactive protein, which were augmented after AIA, were reduced by the PTX regimens. Concomitantly to AIA, mice presented alveolar bone loss, and recruitment of osteoclasts and neutrophils to periodontal tissues. Pre-PTX and The-PTX prevented and treated these signs of PD. PTX treatment also decreased TNF-α and increased IL-10 expression in the maxillae of AIA mice, although it did not affect the expression of IFN-γ and IL-17. SIGNIFICANCE: The current study shows the anti-inflammatory and bone protective effects of preventive and therapeutic PTX treatments, which decreased the joint damage triggered by AIA and the associated periodontal co-morbidity.