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Estimates of the spatiotemporal distribution of different mosquito vector species and the associated risk of transmission of arboviruses are key to design adequate policies for preventing local outbreaks and reducing the number of human infections in endemic areas. In this study, we quantified the abundance of Aedes albopictusand Aedes aegyptiand the local transmission potential for three arboviral infections at an unprecedented spatiotemporal resolution in areas where no entomological surveillance is available.

Aim:Characterize the course of acute Aspergillus fumigatuslung infection in immunocompetent mice, investigating the immunological, pathological and tissue functional modifications. Materials & methods:C57BL/6 mice were intranasally infected with A. fumigatusconidia and euthanized to access inflammatory parameters. Results:Mice infected with A. fumigatusshowed an inoculum-dependent lethality and body weight loss. An intense proinflammatory cytokine release, neutrophil infiltrate and pulmonary dysfunction was also observed in the early phase of infection. In the late phase of infection, proresolving mediators release, apoptosis and efferocytosis increased and lung tissue architecture is restored. Conclusion:Our study characterized an immunocompetent model of acute pulmonary Aspergillusinfection in mice and opened an array of possibilities for investigations on interactions of A. fumigatuswith host-immune system.

CD300a is an inhibitory immunoreceptor expressed in lymphoid and myeloid cells. This study evaluates whether CD300a plays a role in the control of joint inflammation in a model of Ag‐induced arthritis (AIA) in mice. CD300a was found to be expressed mostly on neutrophils and its expression was enhanced on neutrophils that migrated to the inflamed synovial cavity. Joint inflammation, as characterized by neutrophil accumulation, was significantly greater in CD300a KO (CD300a−/−) mice subjected to AIA, as compared to WT mice. This was associated with joint dysfunction, as measured by lower mechanical nociception threshold. There was greater production of the chemokine CXCL1 and the cytokine IL‐6 in joints of CD300a−/−mice. In vitro, Mϕs from CD300a−/−mice released higher concentrations of CXCL1 and IL‐6 in response to LPS. Splenocytes from immunized CD300a−/−mice produced increased levels of IFN‐γ and IL‐17 and lower levels of IL‐10 when challenged with Ag than cells from WT mice. Neutrophils lacking the CD300a gene had greater chemotactic activity in response to fMLP, CXCL1, and LTB4 than WT neutrophils. In conclusion, these results reveal that the absence of CD300a promotes exacerbation of inflammation in a model of Ag‐induced arthritis, suggesting that CD300a is an important receptor for negatively controlling the inflammatory response in this model. Mechanistically, CD300a seems to regulate the activity of various immune cells types involved in the process, including neutrophils, Mϕs, and lymphocytes. In a model of Ag‐induced arthritis, the inhibitory immunoreceptor CD300a regulates joint inflammation induced by Ag by controlling the function of lymphocytes, Mϕs, and neutrophils.

This study investigates the participation of PI3Kγ in the development of joint inflammation and dysfunction in an experimental model of acute gout in mice. Acute gout was induced by injection of monosodium urate (MSU) crystals into the tibiofemoral joint of mice. The involvement of PI3Kγ was evaluated using a selective inhibitor and mice deficient for PI3Kγ (PI3Kγ−/−) or with loss of kinase activity. Neutrophils recovered from the inflamed joint were quantified and stained for phosphorylated Akt (pAkt) and production of reactive oxygen species (ROS). The adherence of leukocytes to the joint microvasculature was assessed by intravital microscopy and cleaved caspase‐1 by Western blot. Injection of MSU crystals induced massive accumulation of neutrophils expressing phosphorylated Akt. In the absence of PI3Kγ, there was reduction of pAkt expression, chemokine production, and neutrophil recruitment. Genetic or pharmacological inhibition of PI3Kγ reduced the adherence of leukocytes to the joint microvasculature, even in joints with established inflammation. Neutrophils from PI3Kγ−/−mice produced less ROS than wild‐type neutrophils. There was decreased joint damage and dysfunction in the absence of PI3Kγ. In addition, in the absence of PI3Kγ activity, there was reduction of cleaved caspase‐1 and IL‐1β production in synovial tissue after injection of MSU crystals and leukotriene B4. Our studies suggest that PI3Kγ is crucial for MSU crystal–induced acute joint inflammation. It is necessary for regulating caspase‐1 activation and for mediating neutrophil migration and activation. Drugs that impair PI3Kγ function may be useful to control acute gout inflammation. PI3Kγ is an important contributor to caspase‐1 activation in earlier events after MSU crystals and LTB4 stimulation.

Posterior urethral valve is the most common lower urinary tract obstruction in male children. A high percentage of patients with posterior urethral valve evolve to end-stage renal disease. Previous studies showed that cytokines, chemokines, and components of the renin–angiotensin system contribute to the renal damage in obstructive uropathies. The authors recently found that urine samples from fetuses with posterior urethral valve have increased levels of inflammatory molecules. The aim of this study was to measure renin–angiotensin system molecules and to investigate their correlation with previously detected inflammatory markers in the same urine samples of fetuses with posterior urethral valve.

Posterior urethral valve is the most common lower urinary tract obstruction in male children. A high percentage of patients with posterior urethral valve evolve to end‐stage renal disease. Previous studies showed that cytokines, chemokines, and components of the renin–angiotensin system contribute to the renal damage in obstructive uropathies. The authors recently found that urine samples from fetuses with posterior urethral valve have increased levels of inflammatory molecules. The aim of this study was to measure renin–angiotensin system molecules and to investigate their correlation with previously detected inflammatory markers in the same urine samples of fetuses with posterior urethral valve.

Zika virus is a mosquito-borne virus that is associated with neurodegenerative diseases, including Guillain–Barré syndrome1and 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.

Supplemental Digital Content is available in the text.

Gout arthritis is a painful inflammatory disease induced by monosodium urate (MSU) crystals. We evaluate the therapeutic potential of the flavonoid hesperidin methylchalcone (HMC) in a mouse model of gout arthritis induced by intra-articular injection of MSU (100 μg/10 μL). Orally given HMC (3–30 mg/kg, 100 μL) reduced in a dose-dependent manner the MSU-induced hyperalgesia (44%, p< 0.05), edema (54%, p< 0.05), and leukocyte infiltration (70%, p< 0.05). HMC (30 mg/kg) inhibited MSU-induced infiltration of LysM-eGFP+cells (81%, p< 0.05), synovitis (76%, p< 0.05), and oxidative stress (increased GSH, FRAP, and ABTS by 62, 78, and 73%, respectively; reduced O2–and NO by 89 and 48%, p< 0.05) and modulated cytokine production (reduced IL-1β, TNF-α, IL-6, and IL-10 by 35, 72, 37, and 46%, respectively, and increased TGF-β by 90%, p< 0.05). HMC also inhibited MSU-induced NF-κB activation (41%, p< 0.05), gp91phox(66%, p< 0.05) and NLRP3 inflammasome components mRNA expression in vivo (72, 77, 71, and 73% for NLRP3, ASC, pro-caspase-1, and pro-IL-1 β, respectively, p< 0.05), and induced Nrf2/HO-1 mRNA expression (3.9- and 5.1-fold increase, respectively, p< 0.05). HMC (30, 100, and 300 μM) did not inhibit IL-1β secretion by macrophages primed by LPS and challenged with MSU (450 μg/mL), demonstrating that the anti-inflammatory effect of HMC in gout arthritis depends on inhibiting NF-κB but not on direct inhibition of inflammasome. The pharmacological effects of HMC indicate its therapeutic potential for the treatment of gout.

Phthalimide analogs have been shown to exhibit anti-inflammatory, analgesic and immunomodulatory activities in different preclinical assays. This study aimed to investigate the potential role of 2-phthalimidethanol (PTD-OH) and 2-phthalimidethyl nitrate (PTD-NO) in a murine model of antigen-induced articular inflammation.

Background: Phthalimide analogs have been shown to exhibit anti-inflammatory, analgesic and immunomodulatory activities in different preclinical assays. This study aimed to investigate the potential role of 2-phthalimidethanol (PTD-OH) and 2-phthalimidethyl nitrate (PTD-NO) in a murine model of antigen-induced articular inflammation. Methods: Articular inflammation was induced by intra-articular injection of methylated bovine serum albumin (mBSA) in the knee joint of immunized male C57BL/6J mice. The animals were pre-treated with PTD-OH or PTD-NO (500 mg/kg, per os, — 1 h). Nociceptive threshold was measured using an electronic von Frey apparatus. The total number of leukocytes in the synovial cavity was determined. Concentrations of tumor necrosis factor (TNF)-a and CXCL-1 and myeloperoxidase (MPO) activity were determined in periarticular tissue. Results: Both PTD-OH and PTD-NO inhibited at similar extent the mechanical allodynia, neutrophil recruitment to the synovial cavity and periarticular tissue and TNF-a and CXCL-1 production induced by intra-articular challenge with mBSA in immunized mice. Conclusions: PTD-OH and PTD-NO exhibit a marked activity in a murine model of antigen-induced articular inflammation in immunized animals. These results reinforce the interest in the investigation of phthalimide analogs devoid of the glutarimide ring as candidates to analgesic and anti-inflammatory drugs.

Inflammation resolution is an active process that functions to restore tissue homeostasis. The participation of the plasminogen (Plg)/plasmin (Pla) system in the productive phase of inflammation is well known, but its involvement in the resolution phase remains unclear. Therefore, we aimed to investigate the potential role of Plg/Pla in key events during the resolution of acute inflammation and its underlying mechanisms. Plg/Pla injection into the pleural cavity of BALB/c mice induced a time-dependent influx of mononuclear cells that were primarily macrophages of anti-inflammatory (M2 [F4/80highGr1–CD11bhigh]) and proresolving (Mres [F4/80medCD11blow]) phenotypes, without changing the number of macrophages with a proinflammatory profile (M1 [F4/80lowGr1+CD11bmed]). Pleural injection of Plg/Pla also increased M2 markers (CD206 and arginase-1) and secretory products (transforming growth factor β and interleukin-6) and decreased the expression of inducible nitric oxide synthase (M1 marker). During the resolving phase of lipopolysaccharide (LPS)-induced inflammation when resolving macrophages predominate, we found increased Plg expression and Pla activity, further supporting a link between the Plg/Pla system and key cellular events in resolution. Indeed, Plg or Pla given at the peak of inflammation promoted resolution by decreasing neutrophil numbers and increasing neutrophil apoptosis and efferocytosis in a serine-protease inhibitor–sensitive manner. Next, we confirmed the ability of Plg/Pla to both promote efferocytosis and override the prosurvival effect of LPS via annexin A1. These findings suggest that Plg and Pla regulate several key steps in inflammation resolution, namely, neutrophil apoptosis, macrophage reprogramming, and efferocytosis, which have a major impact on the establishment of an efficient resolution process.

Inflammation resolution is an active process that functions to restore tissue homeostasis. The participation of the plasminogen (Plg)/plasmin (Pla) system in the productive phase of inflammation is well known, but its involvement in the resolution phase remains unclear. Therefore, we aimed to investigate the potential role of Plg/Pla in key events during the resolution of acute inflammation and its underlying mechanisms. Plg/Pla injection into the pleural cavity of BALB/c mice induced a time-dependent influx of mononuclear cells that were primarily macrophages of anti-inflammatory (M2 [F4/80high Gr1– CD11bhigh]) and proresolving (Mres [F4/80med CD11blow]) phenotypes, without changing the number of macrophages with a proinflammatory profile (M1 [F4/80low Gr1+ CD11bmed]). Pleural injection of Plg/Pla also increased M2 markers (CD206 and arginase-1) and secretory products (transforming growth factor β and interleukin-6) and decreased the expression of inducible nitric oxide synthase (M1 marker). During the resolving phase of lipopolysaccharide (LPS)-induced inflammation when resolving macrophages predominate, we found increased Plg expression and Pla activity, further supporting a link between the Plg/Pla system and key cellular events in resolution. Indeed, Plg or Pla given at the peak of inflammation promoted resolution by decreasing neutrophil numbers and increasing neutrophil apoptosis and efferocytosis in a serine-protease inhibitor–sensitive manner. Next, we confirmed the ability of Plg/Pla to both promote efferocytosis and override the prosurvival effect of LPS via annexin A1. These findings suggest that Plg and Pla regulate several key steps in inflammation resolution, namely, neutrophil apoptosis, macrophage reprogramming, and efferocytosis, which have a major impact on the establishment of an efficient resolution process.

ABSTRACTLeprosy is an important cause of disability in the developing world. Early diagnosis is essential to allow for cure and to interrupt transmission of this infection. MicroRNAs (miRNAs) are important factors for host-pathogen interaction and they have been identified as biomarkers for various infectious diseases. The expression profile of 377 microRNAs were analyzed by TaqMan low-density array (TLDA) in skin lesions of tuberculoid and lepromatous leprosy patients as well as skin specimens from healthy controls. In a second step, 16 microRNAs were selected for validation experiments with reverse transcription-quantitative PCR (qRT-PCR) in skin samples from new individuals. Principal-component analysis followed by logistic regression model and receiver operating characteristic (ROC) curve analyses were performed to evaluate the diagnostic potential of selected miRNAs. Four patterns of differential expression were identified in the TLDA experiment, suggesting a diagnostic potential of miRNAs in leprosy. After validation experiments, a combination of four miRNAs (miR-101, miR-196b, miR-27b, and miR-29c) was revealed as able to discriminate between healthy control and leprosy patients with 80% sensitivity and 91% specificity. This set of miRNAs was also able to discriminate between lepromatous and tuberculoid patients with a sensitivity of 83% and 80% specificity. In this work, it was possible to identify a set of miRNAs with good diagnostic potential for leprosy.

Gout is a disease characterized by the deposition of monosodium urate (MSU) crystals in the joints. Continuous gout episodes may lead to unresolved inflammatory responses and tissue damage. We investigated the effects of a high-fiber diet and acetate, a short-chain fatty acid (SCFA) resulting from the metabolism of fiber by gut microbiota, on the inflammatory response in an experimental model of gout in mice. Injection of MSU crystals into the knee joint of mice induced neutrophil influx and inflammatory hypernociception. The onset of inflammatory response induced by MSU crystals was not altered in animals given a high-fiber diet, but the high-fiber diet induced faster resolution of the inflammatory response. Similar results were obtained in animals given the SCFA acetate. Acetate was effective, even when given after injection of MSU crystals at the peak of the inflammatory response and induced caspase-dependent apoptosis of neutrophils that accounted for the resolution of inflammation. Resolution of neutrophilic inflammation was associated with decreased NF-?B activity and enhanced production of anti-inflammatory mediators, including IL-10, TGF-ß, and annexin A1. Acetate treatment or intake of a high-fiber diet enhanced efferocytosis, an effect also observed in vitro with neutrophils treated with acetate. In conclusion, a high-fiber diet or one of its metabolic products, acetate, controls the inflammatory response to MSU crystals by favoring the resolution of the inflammatory response. Our studies suggest that what we eat plays a determinant role in our capacity to fine tune the inflammatory response. Introduction Beneficial effects of HF and acetate production in a model of gout, by inducing pro-resolutive mediators and neutrophil apoptosis in the joint.

Continued investigation of the polyphenolic pool of the fruits of Mansoa hirsutaafforded four additional members of the new class of glucosylated oligomeric flavonoids comprising a flavanone core linked to 1,3-diarylpropane C6–C3–C6units. The structures and absolute configurations of mansoins C–F (3–6) were established by analysis of NMR and electronic circular dichroism data. Mansoin C (3) was identified as a diglucosylated heterodimer, whereas mansoins D (4), E (5), and F (6) were identified as triglucosylated heterotrimers, isomeric with mansoin A (1). Mansoin F (6) inhibited TNF-α release by lipopolysaccharide-stimulated THP-1 cells (IC50of 19.3 ± 1.3 μM) and, as with mansoin A (1), reduced the phosphorylation levels of p-65-NF-κB, when assayed at 50 μM. These results indicate that the potential anti-inflammatory properties of mansoin F (6) are probably due to inhibition of the NF-κB pathway and inhibition of TNF-α release.

ABSTRACTThe aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor involved in controlling several aspects of immune responses, including the activation and differentiation of specific T cell subsets and antigen-presenting cells, thought to be relevant in the context of experimental Trypanosoma cruziinfection. The relevance of AhR for the outcome of T. cruziinfection is not known and was investigated here. We infected wild-type (WT) mice and AhR knockout (AhR KO) mice with T. cruzi(Y strain) and determined levels of parasitemia, myocardial inflammation and fibrosis, expression of AhR/cytokines/suppressor of cytokine signaling (SOCS) (spleen/heart), and production of nitric oxide (NO), reactive oxygen species (ROS), and peroxynitrite (ONOO−) (spleen). AhR expression was increased in the heart of infected WT mice. Infected AhR KO mice displayed significantly reduced parasitemia, inflammation, and fibrosis of the myocardium. This was associated with an anticipated increased immune response characterized by increased levels of inflammatory cytokines and reduced expression of SOCS2 and SOCS3 in the heart. In vitro, AhR deficiency caused impairment in parasite replication and decreased levels of ROS production. In conclusion, AhR influences the development of murine Chagas disease by modulating ROS production and regulating the expression of key physiological regulators of inflammation, SOCS1 to -3, associated with the production of cytokines during experimental T. cruziinfection.

The relevance of IL-33 and its receptor ST2 for bone remodeling is not well-defined. Our aim was to assess the role and underlying mechanisms of IL-33/ST2 in mechanically induced bone remodeling. BALB/c (wild type) and ST2 deficient (St2−/−) mice were subjected to mechanical loading in alveolar bone. Microtomography, histology, and real-time quantitative PCR were performed to analyze bone parameters, apoptosis and bone cell counts, and expression of bone remodeling markers, respectively. MC3T3-E1 osteoblastic cells and bone marrow cells were used to verify if mechanical force triggered IL-33 and ST2 expression as well as the effects of IL-33 on osteoclast differentiation and activity. Mechanical loading increased the expression of IL-33 and ST2 in alveolar bone in vivoand in osteoblastic cells in vitro. St2−/−mice had increased mechanical loading-induced bone resorption, number of osteoclasts, and expression of proresorptive markers. In contrast, St2−/−mice exhibited reduced numbers of osteoblasts and apoptotic cells in periodontium and diminished expression of osteoblast signaling molecules. In vitro, IL-33 treatment inhibited osteoclast differentiation and activity even in the presence of receptor activator of NF-κB ligand. IL-33 also increased the expression of pro-apoptotic molecules, including Bcl-2-associated X protein (BAX), cell-surface Fas receptor (FAS), FASL, FAS-associated death domain, tumor necrosis factor–related apoptosis-inducing ligand, and BH3 interacting-domain death (BID). Overall, these findings suggest that IL-33/ST2 have anti-osteoclastogenic effects and reduce osteoclast formation and activity by inducing their apoptosis.

American trypanosomiasis, or Chagas disease, is a lifelong and persistent infection caused by the protozoan Trypanosoma cruziand is the most significant cause of morbidity and mortality in South and Central America. Owing to immigration and additional risks from blood transfusion and organ transplantation, the number of reported cases of Chagas disease has increased recently in Europe and the USA. The disease is caused by a moderate to intense lasting inflammatory response that triggers local expression of inflammatory mediators and activates and recruits leukocytes to various tissues to eliminate the parasites.

This protocol describes how to perform liver confocal intravital microscopy in mice, revealing the morphology and function of hepatocytes, endothelial cells and leukocytes in their native environment under physiological or pathological conditions.

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-1β 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-1β and IL-18 production in the ileum. asc−/−and casp-1−/−mice also had less intestinal injury and decreased IL-1β and IL-18 production. Finally, both the absence of IL-18 and IL-1β resulted in reduced inflammatory response and attenuated intestinal injury. NOX-2–derived oxidative stress mediates inflammasome activation and inflammasome-dependent production of IL-1β and IL-18, which mediate tissue injury during irinotecan-induced mucositis in mice.

Mansoins A (1) and B (2) isolated from the fruits of Mansoa hirsutarepresent new glucosylated heterotrimeric flavonoids with a flavanone core linked to two 1,3-diarylpropane C6–C3–C6units. Their structures and absolute configurations were established by analysis of their NMR and electronic circular dichroism spectroscopic data. Compounds 1and 2inhibited TNF-α release by LPS-stimulated THP-1 cells with different potencies, with mansoin B (2) being active at lower concentrations than mansoin A (1) (IC50values 20.0 ± 1.4 and 48.1 ± 1.8 μM, respectively). These results indicate potential anti-inflammatory properties for this structural type of oligoflavonoids, especially for mansoin B (2).

Chagas disease is endemic in Latin America, but the migration of infected individuals makes the condition an increasingly global problem. The authors review the epidemiology, pathogenesis, diagnosis, and treatment of the disease, focusing particularly on the risk stratification and management of patients with Chagas cardiomyopathy.

Red seaweeds are known sources of polysaccharides, some of which possess antiadhesive properties by inhibition of P-selectin-mediated leukocyte rolling. We here report the chemical composition and the antiadhesive activity of polysaccharide-rich fractions from the red alga Lithothamnion muelleri (Hapalidiaceae). The crude fractions enriched in polysaccharides B1 and B2 were obtained, respectively, by sequential extraction with 1% and 2% (w/v) Na2CO3solution, at 60 °C. Fractionation of B1 and B2 by gel permeation chromatography afforded three polysaccharide-rich fractions each, whose compositions were characterized by chemical analysis (total contents of carbohydrates, proteins, sulfate, and uronic acid); their molecular weights were estimated by high-performance gel permeation chromato graphy (HPGPC). The antiadhesive activity of B1-derived fractions was assayed by visualizing lipopolysaccharides-induced leukocyte rolling under intravital miscroscopy. The intravenous injection of fractions B1a and B1b in mice, at the dose of 10 mg/kg body weight, reduced leukocyte rolling by approximately 90%; fucoidan (10 mg/kg body weight) employed as positive control induced a similar response. Therefore, the sulfated polysaccharides of L. muelleri deserve further evaluation as potential templates for the development of new anti-inflammatory agents.

Annexin A1 is a mediator of natural and glucocorticoid‐induced resolution of inflammation, with profound effects on neutrophil apoptosis in vivo. This study aimed at assessing whether AnxA1, a downstream mediator for the anti‐inflammatory effects of GCs, could affect the fate of immune cells in tissue exudates, using LPS‐induced pleurisy in BALB/c mice. AnxA1 protein expression in exudates was increased during natural resolution, as seen at 48–72 h post‐LPS, an effect augmented by treatment with GC and associated with marked presence of apoptotic neutrophils in the pleural exudates. The functional relevance of AnxA1 was determined using a neutralizing antibody or a nonspecific antagonist at FPR/ALXRs: either treatment inhibited both spontaneous and GC‐induced resolution of inflammation. Injection of Ac2‐26 (100 μg, given 4 h into the LPS response), an AnxA1‐active N‐terminal peptide, promoted active resolution and augmented the extent of neutrophil apoptosis. Such an effect was prevented by the pan‐caspase inhibitor zVAD‐fmk. Mechanistically, resolution of neutrophilic inflammation was linked to cell apoptosis with activation of Bax and caspase‐3 and inhibition of survival pathways Mcl‐1, ERK1/2, and NF‐κB. These novel in vivo data, using a dynamic model of acute inflammation, provide evidence that AnxA1 is a mediator of natural and GC‐induced resolution of inflammation with profound effects on neutrophil apoptosis.

Infection with Trypanosoma cruziinduces inflammation, which limits parasite proliferation but may result in chagasic heart disease. Suppressor of cytokine signaling 2 (SOCS2) is a regulator of immune responses and may therefore participate in the pathogenesis of T. cruziinfection. SOCS2 is expressed during T. cruziinfection, and its expression is partially reduced in infected 5-lipoxygenase–deficient [knockout (KO)] mice. In SOCS2 KO mice, there was a reduction in both parasitemia and the expression of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), IL-6, IL-10, SOCS1, and SOCS3 in the spleen. Expression of IFN-γ, TNF-α, SOCS1, and SOCS3 was also reduced in the hearts of infected SOCS2 KO mice. There was an increase in the generation and expansion of T regulatory (Treg) cells and a decrease in the number of memory cells in T. cruzi–infected SOCS2 KO mice. Levels of lipoxinA4(LXA4) increased in these mice. Echocardiography studies demonstrated an impairment of cardiac function in T. cruzi–infected SOCS2 KO mice. There were also changes in calcium handling and in action potential waveforms, and reduced outward potassium currents in isolated cardiac myocytes. Our data suggest that reductions of inflammation and parasitemia in infected SOCS2-deficient mice may be secondary to the increases in Treg cells and LXA4levels. This occurs at the cost of greater infection-associated heart dysfunction, highlighting the relevance of balanced inflammatory and immune responses in preventing severe T. cruzi–induced disease.

The atypical chemokine receptor D6 is a decoy and scavenger receptor for most inflammatory CC chemokines and prevents the development of exacerbated inflammatory reactions. Here we report that mice lacking D6 expression in the nonhematopoietic compartment have a selective increase in the number of Ly6Chighmonocytes in the circulation and in secondary lymphoid tissues. Under inflammatory conditions, Ly6Chighmonocytes accumulate in increased number in secondary lymphoid organs of D6−/−mice in a CCR2-dependent manner. Ly6Chighmonocytes derived from D6−/−mice have enhanced immunosuppressive activity, inhibit the development of adaptive immune responses, and partially protect mice from the development of GVHD. Thus, control of CCR2 ligands by D6 regulates the traffic of Ly6Chighmonocytes and controls their immunosuppressive potential.

The atypical chemokine receptor D6 is a decoy and scavenger receptor for most inflammatory CC chemokines and prevents the development of exacerbated inflammatory reactions. Here we report that mice lacking D6 expression in the nonhematopoietic compartment have a selective increase in the number of Ly6Chigh monocytes in the circulation and in secondary lymphoid tissues. Under inflammatory conditions, Ly6Chigh monocytes accumulate in increased number in secondary lymphoid organs of D6−/− mice in a CCR2-dependent manner. Ly6Chigh monocytes derived from D6−/− mice have enhanced immunosuppressive activity, inhibit the development of adaptive immune responses, and partially protect mice from the development of GVHD. Thus, control of CCR2 ligands by D6 regulates the traffic of Ly6Chigh monocytes and controls their immunosuppressive potential.

PAFR plays a critical role in GVHD by mediating leukocyte influx and cytokine production in target tissues. PAF is a potent lipid mediator involved in several manifestations of acute inflammation, including leukocyte influx, leukocyte interaction with endothelium, and production of inflammatory cytokines. The present study evaluated the relevance of PAFR for the pathogenesis of acute GVHD using a model of adoptive transfer of splenocytes from WT or PAFR−/−C57BL/6J to B6D2F1 mice. Mice, which received PAFR−/−splenocytes or treatment with the PAFR antagonist, showed reduced clinical signs of disease and no mortality. In GVHD mice receiving PAFR−/−splenocytes, there was deceased bacterial translocation and tissue injury. Furthermore, production of proinflammatory cytokines and chemokines (TNF‐α, IFN‐γ, CCL2, CCL3, and CCL5) and accumulation of CD8+cells in intestine and liver were reduced in mice transplanted with the PAFR−/−splenocyte. Mechanistically, an absence or pharmacological blockade of PAFR was associated with decreased rolling and adhesion of leukocytes to the mesenteric microcirculation, as assessed by intravital microscopy. Despite decreased GVHD, there was maintained GVL activity when PAFR−/−leukocytes were transferred into WT mice. In conclusion, PAFR on donor leukocytes plays a critical role in GVHD by mediating leukocyte influx and cytokine production in target tissues. PAFR antagonist may potentially be useful in the treatment of GVHD in bone marrow‐transplanted patients.

Cerebral malaria is a severe form of the disease that may result, in part, from an overt inflammatory response during infection by Plasmodium falciparum. The understanding of the pathogenesis of cerebral malaria may aid in the development of better therapeutic strategies for patients. The immune response in cerebral malaria involves elevation of circulating levels of cytokines and chemokines associated with leukocyte accumulation and breakdown of the blood–brain barrier in the central nervous system. Platelet-activating factor (PAF) is a mediator of inflammation shown to orchestrate inflammatory processes, including recruitment of leukocytes and increase of vascular permeability. Using mice lacking the PAF receptor (PAFR−/−), we investigated the relevance of this molecule for the outcome and the neuroinflammatory process triggered by P. bergheiANKA, an experimental model of cerebral malaria. In PAFR−/−mice, lethality was markedly delayed and brain inflammation was significantly reduced, as demonstrated by histology, accumulation, and activation of CD8+T cells, changes in vascular permeability and activation of caspase-3 on endothelial cells and leukocytes. Similarly, treatment with the PAFR antagonist UK-74,505 delayed lethality. Taken together, the results suggest that PAFR signaling is crucial for the development of experimental cerebral malaria. Mechanistically, PAFR activation is crucial for the cascade of events leading to changes in vascular permeability, accumulation, and activation of CD8+T cells and apoptosis of leukocytes and endothelial cells.

Dengue virus (DENV), a member of the mosquito-borne flaviviruses, is a serious public health problem in many tropical countries. We assessed the in vivophysiologic contribution of invariant natural killer T (iNKT) cells, a population of nonconventional lipid-reactive αβ T lymphocytes, to the host response during experimental DENV infection. We used a mouse-adapted DENV serotype 2 strain that causes a disease that resembles severe dengue in humans. On DENV challenge, splenic and hepatic iNKT cells became activated insofar as CD69 and Fas ligand up-regulation and interferon-γ production. C57BL/6 mice deficient in iNKT cells (Jα18−/−) were more resistant to lethal infection than were wild-type animals, and the phenotype was reversed by adoptive transfer of iNKT cells to Jα18−/−animals. The absence of iNKT cells in Jα18−/−mice was associated with decreased systemic and local inflammatory responses, less liver injury, diminished vascular leak syndrome, and reduced activation of natural killer cells and neutrophils. iNKT cell functions were not necessary for control of primary DENV infection, after either natural endogenous activation or exogenous activation with the canonical iNKT cell agonist α-galactosylceramide. Together, these data reveal a novel and critical role for iNKT cells in the pathogenesis of severe experimental dengue disease.

This study aimed to examine the association between different inflammatory markers and specific clinical endpoints in patients with febrile neutropenia.

Infection by one of the four serotypes of the arthropod‐borne dengue virus produces a spectrum of disease manifestations, ranging from asymptomatic to life‐threatening Dengue hemorrhagic fever/Dengue shock syndrome (DHF/DSS). During the last several decades, dengue has spread its geographic distribution to become the most common arboviral infection of humans in the subtropical and tropical regions of the world. There is no specific treatment or vaccine approved for human use. This fact, associated with the large number of infected individuals and the lack of markers that indicate which patients will develop severe disease, place an enormous burden on health systems of affected countries. Many efforts have been made to elucidate several aspects of dengue disease, but the pathogenesis of disease is complex and remains unclear. The hallmark of severe dengue disease is a short‐lived plasma leakage that is believed to be immune mediated. Understanding the mechanism(s) that underlie the pathogenesis of dengue is critical for the development of safe therapeutics to prevent DHF/DSS. In this review, we highlight potential therapeutic alternatives to treat dengue infection and outline strategies used to develop and research anti‐dengue therapies, focusing on in vivo results obtained using the experimental animal models currently available. Within this context, we discuss the therapeutic potential of novel antiviral molecules, either targeting virus‐encoded functions or the cellular functions needed for viral replication. In addition, we discuss studies using anti‐inflammatory strategies aimed at reducing the exacerbated host response against infection and their potential as promising therapeutic alternatives in severe dengue disease. Drug Dev Res 72:480–500, 2011. © 2011 Wiley‐Liss, Inc.

PI3Kγ plays a critical role in GVHD by mediating leukocyte influx in tissues thereby its inhibition may be useful in the treatment of GVHD in patients undergoing bone marrow transplant. PI3Kγ is thought to mediate leukocyte migration to injured tissues and may be important in the pathogenesis of various T‐lymphocyte‐dependent pathologies, including autoimmune and inflammatory diseases. The present study evaluated the relevance of PI3Kγ in donor cells for the pathogenesis of acute GVHD using a model of adoptive transfer of splenocytes from WT or PI3Kγ−/−C57BL/6J mice to B6D2F1 mice, and mice that received PI3Kγ−/−cells showed reduced clinical signs of disease, bacterial translocation, tissue injury, and lethality rates. This was associated with reduced production of proinflammatory cytokines and chemokines (TNF‐α, IFN‐γ, CCL2, CCL3, and CCL5) and reduced infiltration of CD8+, CD4+, and CD11c+cells in the small intestine. Mechanistically, in addition to decreasing production of proinflammatory mediators, absence or pharmacological blockade of PI3Kγ was associated with decreased rolling and adhesion of leukocytes to the mesenteric microcirculation, as assessed by intravital microscopy. Despite decreased GVHD, there was maintained GVL activity when PI3Kγ−/−leukocytes were transferred into WT mice. In conclusion, PI3Kγ plays a critical role in GVHD by mediating leukocyte influx and activation in tissues. PI3Kγ inhibitors may be useful in the treatment of GVHD in patients undergoing BMT.

Trypanosoma cruzi infection causes intense myocarditis, leading to cardiomyopathy and severe cardiac dysfunction. Protective adaptive immunity depends on balanced signaling through a T cell receptor and coreceptors expressed on the T cell surface. Such coreceptors can trigger stimulatory or inhibitory signals after binding to their ligands in antigen-presenting cells (APC). T. cruzi modulates the expression of coreceptors in lymphocytes after infection. Deregulated inflammation may be due to unbalanced expression of these molecules. Programmed death cell receptor 1 (PD-1) is a negative T cell coreceptor that has been associated with T cell anergy or exhaustion and persistent intracellular infections. We aimed to study the role of PD-1 during T. cruzi-induced acute myocarditis in mice. Cytometry assays showed that PD-1 and its ligands are strongly upregulated in lymphocytes and APC in response to T. cruzi infection in vivo and in vitro. Lymphocytes infiltrating the myocardium exhibited high levels of expression of these molecules. An increased cardiac inflammatory response was found in mice treated with blocking antibodies against PD-1, PD-L1, and to a lesser extent, PD-L2, compared to that found in mice treated with rat IgG. Similar results in PD-1–/–mice were obtained. Moreover, the PD-1 blockade/deficiency led to reduced parasitemia and tissue parasitism but increased mortality. These results suggest the participation of a PD-1 signaling pathway in the control of acute myocarditis induced by T. cruzi and provide additional insight into the regulatory mechanisms in the pathogenesis of Chagas' disease.

ABSTRACTTrypanosoma cruziinfection causes intense myocarditis, leading to cardiomyopathy and severe cardiac dysfunction. Protective adaptive immunity depends on balanced signaling through a T cell receptor and coreceptors expressed on the T cell surface. Such coreceptors can trigger stimulatory or inhibitory signals after binding to their ligands in antigen-presenting cells (APC). T. cruzimodulates the expression of coreceptors in lymphocytes after infection. Deregulated inflammation may be due to unbalanced expression of these molecules. Programmed death cell receptor 1 (PD-1) is a negative T cell coreceptor that has been associated with T cell anergy or exhaustion and persistent intracellular infections. We aimed to study the role of PD-1 during T. cruzi-induced acute myocarditis in mice. Cytometry assays showed that PD-1 and its ligands are strongly upregulated in lymphocytes and APC in response to T. cruziinfection in vivoand in vitro. Lymphocytes infiltrating the myocardium exhibited high levels of expression of these molecules. An increased cardiac inflammatory response was found in mice treated with blocking antibodies against PD-1, PD-L1, and to a lesser extent, PD-L2, compared to that found in mice treated with rat IgG. Similar results in PD-1−/−mice were obtained. Moreover, the PD-1 blockade/deficiency led to reduced parasitemia and tissue parasitism but increased mortality. These results suggest the participation of a PD-1 signaling pathway in the control of acute myocarditis induced by T. cruziand provide additional insight into the regulatory mechanisms in the pathogenesis of Chagas' disease.

The plasma level of the chemokine CCL3 is elevated in patients with chronic severe schistosomiasis mansoni. We have previously shown that CCL3–/–mice with experimental infection showed diminished pathology and worm burden compared to those of wild-type (WT) mice. To elucidate further the role of CC chemokines during schistosomiasis mansoni infection, we evaluated the course of infection in C57BL/6J mice deficient in CCR5, one of the receptors for CCL3. The CCR5 deficiency proved to be remarkably deleterious to the host, since mortality rates reached 70% at 14 weeks postinfection in CCR5–/–mice and 19% in WT mice. The increased lethality was not associated with an increased parasite burden, since similar numbers of eggs and adult worms were found in mice from both groups. Liver granulomas of chronically infected CCR5–/–mice were larger and showed greater numbers of cells and collagen deposition than liver granulomas from WT mice. This was associated with higher levels of production of intereleukin-5 (IL-5), IL-13, CCL3, and CCL5 in infected CCR5–/–mice than in infected WT mice. Moreover, at 8 weeks after infection, just before changes in pathology and mortality, the numbers of FoxP3-positive cells were lower in liver granulomas of CCR5–/–mice than in WT mice. In conclusion, the CCR5 deletion is deleterious to mice infected with Schistosoma mansoni, and this is associated with enhanced fibrosis and granulomatous inflammation.

ABSTRACTThe plasma level of the chemokine CCL3 is elevated in patients with chronic severe schistosomiasis mansoni. We have previously shown that CCL3−/−mice with experimental infection showed diminished pathology and worm burden compared to those of wild-type (WT) mice. To elucidate further the role of CC chemokines during schistosomiasis mansoni infection, we evaluated the course of infection in C57BL/6J mice deficient in CCR5, one of the receptors for CCL3. The CCR5 deficiency proved to be remarkably deleterious to the host, since mortality rates reached 70% at 14 weeks postinfection in CCR5−/−mice and 19% in WT mice. The increased lethality was not associated with an increased parasite burden, since similar numbers of eggs and adult worms were found in mice from both groups. Liver granulomas of chronically infected CCR5−/−mice were larger and showed greater numbers of cells and collagen deposition than liver granulomas from WT mice. This was associated with higher levels of production of intereleukin-5 (IL-5), IL-13, CCL3, and CCL5 in infected CCR5−/−mice than in infected WT mice. Moreover, at 8 weeks after infection, just before changes in pathology and mortality, the numbers of FoxP3-positive cells were lower in liver granulomas of CCR5−/−mice than in WT mice. In conclusion, the CCR5 deletion is deleterious to mice infected with Schistosoma mansoni, and this is associated with enhanced fibrosis and granulomatous inflammation.

PI3Kγ is important to drive the fibrotic processes by regulation of pulmonary inflammation and angiogenesis in mice, suggesting PI3Kγ as therapeutic target for pulmonary fibrosis. PI3Kγ is central in signaling diverse arrays of cellular functions and inflammation. Pulmonary fibrosis is associated with pulmonary inflammation, angiogenesis, and deposition of collagen and is modeled by instillation of bleomycin. The role of PI3Kγ in mediating bleomycin‐induced pulmonary inflammation and fibrosis in mice and potential mechanisms involved was investigated here. WT or PI3Kγ KO mice were instilled with bleomycin and leukocyte subtype influx, cytokine and chemokine levels, and angiogenesis and tissue fibrosis evaluated. The activation of lung‐derived leukocytes and fibroblasts was evaluated in vitro. The relevance of PI3Kγ for endothelial cell function was evaluated in HUVECs. PI3Kγ KO mice had greater survival and weight recovery and less fibrosis than WT mice after bleomycin instillation. This was associated with decreased production of TGF‐β1and CCL2 and increased production of IFN‐γ and IL‐10. There was reduced expression of collagen, fibronectin, α‐SMA, and von Willebrand factor and decreased numbers and activation of leukocytes and phosphorylation of AKT and IκB‐α. PI3Kγ KO mice had a reduced number and area of blood vessels in the lungs. In vitro, treatment of human endothelial cells with the PI3Kγ inhibitor AS605240 decreased proliferation, migration, and formation of capillary‐like structures. AS605240 also decreased production of collagen by murine lung‐derived fibroblasts. PI3Kγ deficiency confers protection against bleomycin‐induced pulmonary injury, angiogenesis, and fibrosis through the modulation of leukocyte, fibroblast, and endothelial cell functions. Inhibitors of PI3Kγ may be beneficial for the treatment of pulmonary fibrosis.

The effects of physalin F (1), a steroid derivative purified from Physalis angulata, were investigated in models of collagen-induced arthritis in DBA/1 mice and allergic airway inflammation in BALB/c mice. Oral treatment with 1or dexamethasone caused a marked decrease in paw edema and joint inflammation when compared to vehicle-treated arthritic mice. In contrast, treatment with 1had no effect in mice with allergic airway inflammation caused by ovalbumin immunization, whereas dexamethasone significantly reduced the number of inflammatory cells and eosinophils in the broncoalveolar lavage fluid and in lung sections of challenged mice. To further demonstrate that 1acts through a mechanism different from that of glucocorticoids, a nuclear translocation assay was performed of the glucocorticoid receptor (GR) using COS-7 cells transfected with a plasmid encoding for a yellow fluorescent protein (YFP)−GR fusion protein. Untreated or treated cells with 1had YFP staining mainly in the cytoplasm, whereas in dexamethasone-treated cells the YFP staining was concentrated in the nuclei. It is concluded that the mechanism of the immunosuppressive activity of physalin F is distinct from that of the glucocorticoids.

PDE4 inhibition is effective at resolving neutrophilic inflammation after LPS‐challenge by promoting caspase‐3‐dependent apoptosis of inflammatory cells in the pleural cavity. PDE4 inhibitors are effective anti‐inflammatory drugs whose effects and putative mechanisms on resolution of inflammation and neutrophil apoptosis in vivo are still unclear. Here, we examined the effects of specific PDE4 inhibition on the resolution of neutrophilic inflammation in the pleural cavity of LPS‐challenged mice. LPS induced neutrophil recruitment that was increased at 4 h, peaked at 8–24 h, and declined thereafter. Such an event in the pleural cavity was preceded by increased levels of KC and MIP‐2 at 1 and 2 h. Treatment with the PDE4 inhibitor rolipram, at 4 h after LPS administration, decreased the number of neutrophils and increased the percentage of apoptotic cells in the pleural cavity in a PKA‐dependent manner. Conversely, delayed treatment with a CXCR2 antagonist failed to prevent neutrophil recruitment. Forskolin and db‐cAMP also decreased the number of neutrophils and increased apoptosis in the pleural cavity. The proapoptotic effect of rolipram was associated with decreased levels of the prosurvival protein Mcl‐1 and increased caspase‐3 cleavage. The pan‐caspase inhibitor zVAD‐fmk prevented rolipram‐induced resolution of inflammation. LPS resulted in a time‐dependent activation of Akt, which was blocked by treatment with rolipram or PI3K and Akt inhibitors, and PI3K and Akt inhibitors also enhanced apoptosis and promoted neutrophil clearance. Although LPS induced NF‐κB activation, which was blocked by rolipram, NF‐κB inhibitors did not promote resolution of neutrophil accumulation in this model. In conclusion, our data show that PDE4 inhibition resolves neutrophilic inflammation by promoting caspase‐dependent apoptosis of inflammatory cells by targeting a PKA/PI3K/Akt‐dependent survival pathway.

Eosinophils are multifunctional leukocytes implicated in numerous inflammatory diseases. The present study was conducted to clarify the precise role of eosinophils in the development of colitis by using eosinophil-depleted mice and a novel chemokine-binding protein that neutralizes CCL11 action. Colitis was induced by administration of dextran sodium sulfate (DSS) to wild-type and eosinophil-deficient ΔdblGATA-1 mice. Accumulation of eosinophils in the gut of mice given DSS paralleled worsening of clinical score and weight loss. In response to DSS, ΔdblGATA-1 mice showed virtual absence of eosinophil recruitment, amelioration of clinical score, weight loss, and tissue destruction, and no lethality. There was a decrease in CXCL1 and CCL3 production and decreased neutrophil influx in the intestine of ΔdblGATA-1 mice. Transfer of bone marrow cells from wild-type mice reconstituted disease manifestation in DSS-treated ΔdblGATA-1 mice, and levels of CCL11 were increased after DSS treatment and localized to inflammatory cells. Treatment with the chemokine-binding protein evasin-4 at a dose that prevented the function of CCL11 greatly ameliorated clinical score, weight loss, overall tissue destruction, and death rates. In conclusion, the influx of eosinophils is critical for the induction of colitis by DSS. Treatment with a novel chemokine-binding protein decreased eosinophil influx and greatly ameliorated colitis, suggesting that strategies that interfere with the recruitment of eosinophils may be useful as therapy for colitis.