High mobility group box 1, ATP, lipid mediators, and tissue factor are elevated in COVID-19 patients: HMGB1 as a biomarker of worst prognosis.

The severe acute respiratory syndrome coronavirus 2, the agent of the ongoing coronavirus disease 2019 (COVID-19) pandemic, has spread worldwide since it was first identified in November 2019 in Wuhan, China. Since then, progress in pathogenesis linked severity of this systemic disease to the hyperactivation of network of cytokine-driven pro-inflammatory cascades. Here, we aimed to identify molecular biomarkers of disease severity by measuring the serum levels of inflammatory mediators in a Brazilian cohort of patients with COVID-19 and healthy controls (HCs). Critically ill patients in the intensive care unit were defined as such by dependence on oxygen supplementation (93% intubated and 7% face mask), and computed tomography profiles showing ground-glass opacity pneumonia associated to and high levels of D-dimer. Our panel of mediators included HMGB1, ATP, tissue factor, PGE2 , LTB4 , and cys-LTs. Follow-up studies showed increased serum levels of every inflammatory mediator in patients with COVID-19 as compared to HCs. Originally acting as a transcription factor, HMGB1 acquires pro-inflammatory functions following secretion by activated leukocytes or necrotic tissues. Serum levels of HMGB1 were positively correlated with cys-LTs, D-dimer, aspartate aminotransferase, and alanine aminotransferase. Notably, the levels of the classical alarmin HMGB1 were higher in deceased patients, allowing their discrimination from patients that had been discharged at the early pulmonary and hyperinflammatory phase of COVID-19. In particular, we verified that HMGB1 levels above 125.4 ng/ml is the cutoff that distinguishes patients that are at higher risk of death. In conclusion, we propose the use of serum levels of HMGB1 as a biomarker of severe prognosis of COVID-19.

Skeletal Muscle Is an Early Site of Zika Virus Replication and Injury, Which Impairs Myogenesis.

Zika virus (ZIKV) infection became a worldwide concern due to its correlation with the development of microcephaly and other neurological disorders. ZIKV neurotropism is well characterized, but the role of peripheral viral amplification to brain infection remains unknown. Here, we found that ZIKV replicates in human primary skeletal muscle myoblasts, impairing its differentiation into myotubes but not interfering with the integrity of the already-formed muscle fibers. Using mouse models, we showed ZIKV tropism to muscle tissue either during embryogenesis after maternal transmission or when infection occurred after birth. Interestingly, ZIKV replication in the mouse skeletal muscle started immediately after ZIKV inoculation, preceding viral RNA detection in the brain and causing no disruption to the integrity of the blood brain barrier, and remained active for more than 2 weeks, whereas replication in the spleen and liver were not sustained over time. In addition, ZIKV infection of the skeletal muscle induces necrotic lesions, inflammation, and fiber atrophy. We also found a reduction in the expression of regulatory myogenic factors that are essential for muscle repair after injury. Taken together, our results indicate that the skeletal muscle is an early site of viral amplification and lesion that may result in late consequences in muscle development after ZIKV infection. IMPORTANCE Zika Virus (ZIKV) neurotropism and its deleterious effects on central nervous system have been well characterized. However, investigations of the initial replication sites for the establishment of infection and viral spread to neural tissues remain underexplored. A complete description of the range of ZIKV-induced lesions and others factors that can influence the severity of the disease is necessary to prevent ZIKV's deleterious effects. ZIKV has been shown to access the central nervous system without significantly affecting blood-brain barrier permeability. Here, we demonstrated that skeletal muscle is an earlier site of ZIKV replication, contributing to the increase of peripheral ZIKV load. ZIKV replication in muscle promotes necrotic lesions and inflammation and also impairs myogenesis. Overall, our findings showed that skeletal muscle is involved in pathogenesis and opens new fields in the investigation of the long-term consequences of early infection.

Adenosine Diphosphate Improves Wound Healing in Diabetic Mice Through P2Y12 Receptor Activation.

Chronic wounds are a public health problem worldwide, especially those related to diabetes. Besides being an enormous burden to patients, it challenges wound care professionals and causes a great financial cost to health system. Considering the absence of effective treatments for chronic wounds, our aim was to better understand the pathophysiology of tissue repair in diabetes in order to find alternative strategies to accelerate wound healing. Nucleotides have been described as extracellular signaling molecules in different inflammatory processes, including tissue repair. Adenosine-5'-diphosphate (ADP) plays important roles in vascular and cellular response and is immediately released after tissue injury, mainly from platelets. However, despite the well described effect on platelet aggregation during inflammation and injury, little is known about the role of ADP on the multiple steps of tissue repair, particularly in skin wounds. Therefore, we used the full-thickness excisional wound model to evaluate the effect of local ADP application in wounds of diabetic mice. ADP accelerated cutaneous wound healing, improved new tissue formation, and increased both collagen deposition and transforming growth factor-ß (TGF-ß) production in the wound. These effects were mediated by P2Y12 receptor activation since they were inhibited by Clopidogrel (Clop) treatment, a P2Y12 receptor antagonist. Furthermore, P2Y1 receptor antagonist also blocked ADP-induced wound closure until day 7, suggesting its involvement early in repair process. Interestingly, ADP treatment increased the expression of P2Y12 and P2Y1 receptors in the wound. In parallel, ADP reduced reactive oxygen species (ROS) formation and tumor necrosis factor-α (TNF-α) levels, while increased IL-13 levels in the skin. Also, ADP increased the counts of neutrophils, eosinophils, mast cells, and gamma delta (γδ) T cells (Vγ4+ and Vγ5+ cells subtypes of γδ+ T cells), although reduced regulatory T (Tregs) cells in the lesion. In accordance, ADP increased fibroblast proliferation and migration, myofibroblast differentiation, and keratinocyte proliferation. In conclusion, we provide strong evidence that ADP acts as a pro-resolution mediator in diabetes-associated skin wounds and is a promising intervention target for this worldwide problem.

Downregulation of Microparticle Release and Pro-Inflammatory Properties of Activated Human Polymorphonuclear Neutrophils by LMW Fucoidan.

Exposition of neutrophils (polymorphonuclear neutrophils, PMNs) to bacterial products triggers exacerbated activation of these cells, increasing their harmful effects on host tissues. We evaluated the possibility of interfering with the classic immune innate responses of human PMNs exposed to bacterial endotoxin (lipopolysaccharide, LPS), and further stimulated with bacterial formyl peptide (N-formyl-methionine-leucine-phenylalanine, fMLP). We showed that the low- molecular-weight fucoidan (LMW-Fuc), a polysaccharide extracted from brown algae, attenuated the exacerbated activation induced by fMLP on LPS-primed PMNs, in vitro, impairing chemotaxis, NET formation, and the pro-survival and pro-oxidative effects. LMW-Fuc also inhibited the activation of canonical signaling pathways, AKT, bad, p47phox and MLC, activated by the exposition of PMN to bacterial products. The activation of PMN by sequential exposure to LPS and fMLP induced the release of L-selectin+ microparticles, which were able to trigger extracellular reactive oxygen species production by fresh PMNs and macrophages. Furthermore, we observed that LMW-Fuc inhibited microparticle release from activated PMN. In vivo experiments showed that circulating PMN-derived microparticles could be detected in mice exposed to bacterial products (LPS/fMLP), being downregulated in animals treated with LMW-Fuc. The data highlight the autocrine and paracrine role of pro-inflammatory microparticles derived from activated PMN and demonstrate the anti-inflammatory effects of LMW-Fuc on these cells.

Wound healing properties of Copaifera paupera in diabetic mice.

Copaifera oleoresin is one of the most used natural products in popular medicine all over the world. Among other effects (i.e., anti-inflammatory, antinociceptive, microbicidal) one of the most well-known is its wound healing capacity. However, the mechanism by which the oleoresin presents its effect is still not clear. In this study, our aim was to evaluate the wound healing capacity of oleoresin obtained from Copaifera paupera, its mechanism of action and identify its major components. For these purposes, diabetic Swiss Webster mice were topically treated with oleoresin (100, 150 or 200 mg/kg) for 14 consecutive days after an excision was performed in the back of the mice. Cytokines, wound retraction and histological evaluation were conducted at 3, 7 and 10 days (for cytokines); 0, 3, 7, 10 and 14 days (for wound retraction); and 7 and 14 days (for histological evaluation). Our data indicate that oleoresin significantly reduced production of MCP-1 and TNF-α at days 7 and 10 post-excision and increased IL-10 production at both days. All treatments demonstrated an effect similar or higher to that in collagenase-treated mice. Histological evaluations demonstrated that higher dose treatment resulted in better resolution and closure of the wound and higher levels of collagen deposition and indexes of re-epithelialization even when compared with the collagenase-treated group. The treatment with oleoresin from Copaifera paupera demonstrated that it is even better than an ointment routinely used for improvement of wound healing, suggesting this oleoresin as an option for use in diabetic patients.

Pharmacological modulation of reactive oxygen species (ROS) improves the airway hyperresponsiveness by shifting the Th1 response in allergic inflammation induced by ovalbumin.

Asthma is an allergic inflammation driven by the Th2 immune response with release of cytokines such as IL-4 and IL-13, which contribute to the airflow limitations and airway hyperresponsiveness (AHR). The involvement of oxidative stress in this process is well-established, but the specific role of the superoxide anion and nitric oxide in asthma are poorly understood. Thus, the aim of this study was to investigate the mechanisms underlying the superoxide anion/nitric oxide production and detoxification in a murine asthma model. BALB/c male mice were sensitised and challenged with ovalbumin (OVA). Pretreatments with either apocynin (14 mg/kg) or allopurinol (25 mg/kg) (superoxide anion synthesis inhibitors), aminoguanidine (50 mg/kg) (nitric oxide synthesis inhibitor) or diethyldithiocarbamate (100 mg/kg) (superoxide dismutase inhibitor) were performed 1 h before the challenge. Our data showed that apocynin and allopurinol ameliorated AHR and reduced eosinophil peroxidase, as well as IL-4 and IL-13 levels. Apocynin also abrogated leukocyte peribronchiolar infiltrate and increased IL-1ß secretion. Aminoguanidine preserved lung function and shifted the Th2 to the Th1 response with a reduction of IL-4 and IL-13 and increase in IL-1ß production. Diethyldithiocarbamate prevented neither allergen-induced AHR nor eosinophil peroxidase (EPO) generation. All treatments protected against oxidative damage observed by a reduction in TBARS levels. Taken together, these results suggest that AHR in an asthma model can be avoided by the down-regulation of superoxide anion and nitric oxide synthesis in a mechanism that is independent of a redox response. This down-regulation is also associated with a transition in the typical immunological Th2 response toward the Th1 profile.

Elastase modifies bleomycin-induced pulmonary fibrosis in mice.

Pulmonary fibrosis (PF) is characterized by excessive accumulation of collagen in the lungs. Emphysema is characterized by loss of the extracellular matrix (ECM) and alveolar enlargement. We studied the co-participation of elastase-induced mild emphysema in bleomycin-induced PF in mice by analyzing oxidative stress, inflammation and lung histology. C57BL/6 mice were divided into four groups: control; bleomycin (0.1U/mouse); elastase (using porcine pancreatic elastase (PPE)+bleomycin (3U/mouse 14 days before 0.1U/mouse of bleomycin; PPE+B); elastase (3U/mouse). Mice were humanely sacrificed 7, 14 and 21 days after treatment with bleomycin or vehicle. PF was observed 14 days and 21 days after bleomycin treatment but was observed after 14 days only in the PPE+B group. In the PPE+B group at 21 days, we observed many alveoli and alveolar septa with few PF areas. We also observed marked and progressive increases of collagens 7, 14 and 21 days after bleomycin treatment whereas, in the PPE+B group, collagen deposition was observed only at 14 days. There was a reduction in activities of the antioxidant enzymes superoxide dismutase (p<0.05), catalase (p<0.01) and glutathione peroxidase (p<0.01) parallel with an increase in nitrite (p<0.01) 21 days after bleomycin treatment compared with the control group. These endpoints were also reduced (p<0.05, p<0.05 and p<0.01, respectively) and increased (p<0.01) in the PPE+B group at 21 days compared with the control group. Interleukin (IL)-1ß expression was upregulated (p<0.01) whereas IL-6 was downregulated (p<0.05) in the PPE+B group at 21 days compared with the control group. PF and emphysema did not coexist in our model of lung disease and despite increased levels of oxidative stress and inflammatory markers after combined stimulus (elastase and bleomycin) overall histology was improved to that of the nearest control group.

Murine IL-17+ Vγ4 T lymphocytes accumulate in the lungs and play a protective role during severe sepsis.

BACKGROUND: Lung inflammation is a major consequence of the systemic inflammatory response caused by severe sepsis. Increased migration of γδ T lymphocytes into the lungs has been previously demonstrated during experimental sepsis; however, the involvement of the γδ T cell subtype Vγ4 has not been previously described. METHODS: Severe sepsis was induced by cecal ligation and puncture (CLP; 9 punctures, 21G needle) in male C57BL/6 mice. γδ and Vγ4 T lymphocyte depletion was performed by 3A10 and UC3-10A6 mAb i.p. administration, respectively. Lung infiltrating T lymphocytes, IL-17 production and mortality rate were evaluated. RESULTS: Severe sepsis induced by CLP in C57BL/6 mice led to an intense lung inflammatory response, marked by the accumulation of γδ T lymphocytes (comprising the Vγ4 subtype). γδ T lymphocytes present in the lungs of CLP mice were likely to be originated from peripheral lymphoid organs and migrated towards CCL2, CCL3 and CCL5, which were highly produced in response to CLP-induced sepsis. Increased expression of CD25 by Vγ4 T lymphocytes was observed in spleen earlier than that by αß T cells, suggesting the early activation of Vγ4 T cells. The Vγ4 T lymphocyte subset predominated among the IL-17(+) cell populations present in the lungs of CLP mice (unlike Vγ1 and αß T lymphocytes) and was strongly biased toward IL-17 rather than toward IFN-γ production. Accordingly, the in vivo administration of anti-Vγ4 mAb abrogated CLP-induced IL-17 production in mouse lungs. Furthermore, anti-Vγ4 mAb treatment accelerated mortality rate in severe septic mice, demonstrating that Vγ4 T lymphocyte play a beneficial role in host defense. CONCLUSIONS: Overall, our findings provide evidence that early-activated Vγ4 T lymphocytes are the main responsible cells for IL-17 production in inflamed lungs during the course of sepsis and delay mortality of septic mice.

The P2X7 Receptor Contributes to the Development of the Exacerbated Inflammatory Response Associated with Sepsis.

BACKGROUND: Sepsis is associated with high mortality rates in intensive care units worldwide and represents a systemic inflammatory response to infection. P2X7 is an ionotropic purine receptor with known proinflammatory activity. Here, we investigated the role of the P2X7 receptor in sepsis induced by cecal ligation and puncture (CLP). METHODS: Wild-type (WT) and P2X7KO (P2X7 null) mice were subjected to CLP and their survival was monitored for 7 days. Blood, peritoneal wash and lungs were collected 24 h after CLP and used to measure bacterial load, immune cell infiltration, nitric oxide (NO), cytokine levels, and peritoneal cell death and to assess lung injury. RESULTS: P2X7KO mice showed significantly increased survival 7 days after CLP (30% compared to 60% in WT animals) accompanied by an overall attenuated inflammatory response, with decreased cell recruitment to the peritoneum, no or limited increases in the levels of NO and proinflammatory cytokines (IL-1ß, IL-6, IL-12, IL-17, and IL-4), reduced peritoneal cell apoptosis, and less pronounced lung infiltration and morphological changes. CONCLUSIONS: Our data show the P2X7 receptor is required for the development of the inflammatory response associated with sepsis and support the notion that P2X7 receptor is a valid therapeutic target against inflammatory diseases.

Activated Microglia-Induced Deficits in Excitatory Synapses Through IL-1ß: Implications for Cognitive Impairment in Sepsis.

Recent clinical studies have shown that sepsis survivors may develop long-term cognitive impairments. The cellular and molecular mechanisms involved in these events are not well understood. This study investigated synaptic deficits in sepsis and the involvement of glial cells in this process. Septic animals showed memory impairment and reduced numbers of hippocampal and cortical excitatory synapses, identified by synaptophysin/PSD-95 co-localization, 9 days after disease onset. The behavioral deficits and synaptophysin/PSD-95 co-localization were rescued to normal levels within 30 days post-sepsis. Septic mice presented activation of microglia and reactive astrogliosis, which are hallmarks of brain injury and could be involved in the associated synaptic deficits. We treated neuronal cultures with conditioned medium derived from cultured astrocytes (ACM) and microglia (MCM) that were either non-stimulated or stimulated with lipopolysaccharide (LPS) to investigate the molecular mechanisms underlying synaptic deficits in sepsis. ACM and MCM increased the number of synapses between cortical neurons in vitro, and these effects were antagonized by LPS stimulation. LPS-MCM reduced the number of synapses by 50%, but LPS-ACM increased the number of synapses by 500%. Analysis of the composition of these conditioned media revealed increased levels of IL-1ß in LPS-MCM. Furthermore, inhibition of IL-1ß signaling through the addition of a soluble IL-1ß receptor antagonist (IL-1 Ra) fully prevented the synaptic deficit induced by LPS-MCM. These results suggest that sepsis induces a transient synaptic deficit associated with memory impairments mediated by IL-1ß secreted by activated microglia.

Oxidative stress and inflammation are differentially affected by atorvastatin, pravastatin, rosuvastatin, and simvastatin on lungs from mice exposed to cigarette smoke.

Our aim was to investigate the effects of four different statins on acute lung inflammation induced by cigarette smoke (CS). C57BL/6 male mice were divided into a control group (sham-smoked) and mice exposed to CS from 12 cigarettes/day for 5 days. Mice exposed to CS were grouped and treated with vehicle (i.p.), atorvastatin (10 mg/kg), pravastatin (10 mg/kg), rosuvastatin (5 mg/kg), or simvastatin (20 mg/kg). Treatment with statins differentially improved the pulmonary response when compared to the CS group. Atorvastatin and pravastatin demonstrated slightly effects on inflammation and oxidative stress. Rosuvastatin demonstrated the best anti-inflammatory effect, whereas simvastatin demonstrated the best antioxidant response.

Critical role for CCR2 and HMGB1 in induction of experimental endotoxic shock.

Our aim was to investigate CCR2 and HMGB1 involvement in a murine model of endotoxic shock. We used C57BL/6 CCR2 knockout (KO) mice and wild-type (WT) littermates to establish an optimal dose of LPS. CCR2 KO mice survived more frequently than WT mice after 80, 40 and 20 mg/kg of LPS i.p. Inflammation and redox markers were high in WT mice than in CCR2 KO mice. HMGB1 expression was reduced in CCR2 KO mice in parallel to ERK 1/2 activation. Therefore, we used glycyrrhizic acid (50 mg/kg), an HMGB1 inhibitor in WT mice injected with LPS, and mortality was fully abolished. Thus, drugs targeting CCR2 and HMGB1 could represent future resources for sepsis treatment.

Lack of galectin-3 speeds Wallerian degeneration by altering TLR and pro-inflammatory cytokine expressions in injured sciatic nerve.

Wallerian degeneration (WD) comprises a series of events that includes activation of non-neuronal cells and recruitment of immune cells, creating an inflammatory milieu that leads to extensive nerve fragmentation and subsequent clearance of the myelin debris, both of which are necessary prerequisites for effective nerve regeneration. Previously, we documented accelerated axon regeneration in animals lacking galectin-3 (Gal-3), a molecule associated with myelin clearance. To clarify the mechanisms underlying this enhanced regeneration, we focus here on the early steps of WD following sciatic nerve crush in Gal-3(-/-) mice. Using an in vivo model of nerve degeneration, we observed that removal of myelin debris is more efficient in Gal-3(-/-) than in wild-type (WT) mice; we next used an in vitro phagocytosis assay to document that the phagocytic potential of macrophages and Schwann cells was enhanced in the Gal-3(-/-) mice. Moreover, both RNA and protein levels for the pro-inflammatory cytokines IL-1ß and TNF-α, as well as for Toll-like receptor (TLR)-2 and -4, show robust increases in injured nerves from Gal-3(-/-) mice compared to those from WT mice. Collectively, these data indicate that the lack of Gal-3 results in an augmented inflammatory profile that involves the TLR-cytokine pathway, and increases the phagocytic capacity of Schwann cells and macrophages, which ultimately contributes to speeding the course of WD.

Ketoprofen impairs immunosuppression induced by severe sepsis and reveals an important role for prostaglandin E2.

The mechanism of immunosuppression induced by severe sepsis is not fully understood. The production of prostaglandin E2 (PGE2) during sepsis is well known, but its role in long-term consequences of sepsis has not been explored. The current study evaluates the role of PGE2 in the development of immunosuppression secondary to sepsis and its potential as therapeutic target. Cecal ligation and puncture was used as an experimental model for sepsis induction in Balb/c and C57BL/6 mice. Immunosuppression was evaluated by the response to secondary infection with Aspergillus fumigatus in sepsis survivors. The role of prostanoids was evaluated in vivo and in vitro by treatment with the cyclooxygenase inhibitor ketoprofen. Balb/c mice were more susceptible than C57BL/6 to severe sepsis and to secondary infection, with a greater mortality rate. Prostaglandin E2 concentrations found in bronchoalveolar lavage in sham and cecal ligation and puncture group after fungal challenge were much higher in Balb/c than in C57BL/6 mice. Ketoprofen treatment improved survival of septic Balb/c mice subjected to secondary infection, while also enhancing macrophage phagocytosis and neutrophil recruitment to the lungs. We identified a pivotal role for PGE2 acting on EP4 receptors in modulating cytokine production differentially by sham and septic macrophages. Furthermore, sepsis also altered key enzymes in PGE2 synthesis and degradation. Our results indicate the involvement of PGE2 in severe sepsis-induced immunosuppression. Inhibition of PGE2 production represents an attractive target to improve innate immune response against secondary infection in the immunocompromised host.

Oxidative stress and nitrosative stress are involved in different stages of proteolytic pulmonary emphysema.

Our aim was to investigate the role of oxidative stress in elastase-induced pulmonary emphysema. C57BL/6 mice were subjected to pancreatic porcine elastase (PPE) instillation (0.05 or 0.5 U per mouse, i.t.) to induce pulmonary emphysema. Lungs were collected on days 7, 14, and 21 after PPE instillation. The control group was sham injected. Also, mice treated with 1% aminoguanidine (AMG) and inducible NO synthase (iNOS) knockout mice received 0.5 U PPE (i.t.), and lungs were analyzed 21 days after. We performed bronchoalveolar lavage, biochemical analyses of oxidative stress, and lung stereology and morphometry assays. Emphysema was observed histologically at 21 days after 0.5 U PPE treatment; tissues from these mice exhibited increased alveolar linear intercept and air-space volume density in comparison with the control group. TNF-α was elevated at 7 and 14 days after 0.5 U PPE treatment, concomitant with a reduction in the IL-10 levels at the same time points. Myeloperoxidase was elevated in all groups treated with 0.5 U PPE. Oxidative stress was observed during early stages of emphysema, with increased nitrite levels and malondialdehyde and superoxide dismutase activity at 7 days after 0.5 U PPE treatment. Glutathione peroxidase activity was increased in all groups treated with 0.5 U PPE. The emphysema was attenuated when iNOS was inhibited using 1% AMG and in iNOS knockout mice. Furthermore, proteolytic stimulation by PPE enhanced the expression of nitrotyrosine and iNOS, whereas the PPE+AMG group showed low expression of iNOS and nitrotyrosine. PPE stimulus also induced endothelial (e) NOS expression, whereas AMG reduced eNOS. Our results suggest that the oxidative and nitrosative stress pathways are triggered by nitric oxide production via iNOS expression in pulmonary emphysema.

Evaluation of 3-(3-chloro-phenyl)-5-(4-pyridyl)-4,5-dihydroisoxazole as a novel anti-inflammatory drug candidate.

BACKGROUND: 3-(3-chloro-phenyl)-5-(4-pyridyl)-4,5-dihydroisoxazole (DIC) is a five-membered heterocyclic compound containing a N-O bond. The anti-inflammatory effects of this compound were studied both in vitro and in vivo. PRINCIPAL FINDINGS: DIC effectively decreased TNF-α and IL-6 release from LPS-stimulated macrophages in a dose dependent manner. DIC diminished the levels of COX-2 with subsequent inhibition of PGE(2) production. DIC also compromised HMGB1 translocation from the nucleus to the cytoplasm. Moreover, DIC prevented the nuclear translocation of NF-κB and inhibited the MAPK pathway. In vivo, DIC inhibited migration of neutrophils to the peritoneal cavity of mice. CONCLUSIONS: This study presents the potential utilization of a synthetic compound, as a lead for the development of novel anti-inflammatory drugs.

Endotoxin-induced acute lung injury is dependent upon oxidative response.

The aim of the present study was to investigate the involvement of oxidative stress in acute lung injury (ALI) induced by lipopolysaccharide (LPS) and its effects upon cell structure, function and inflammation. In total, 108 male C57BL/6 mice were divided into seven groups: CTR Group (50 µL of saline) administered intratracheally (i.t.), LPS 6 h (10 µg of LPS - i.t.), LPS 12 h (10 µg of LPS - i.t.), LPS 24 h (10 µg of LPS - i.t.), LPS 48 h (10 µg of LPS - i.t.), LPS 24 h (10 µg - i.t.) + NAC 40 mg/kg (gavage) and 24 h LPS (10 µg - i.t.) + NAC 100 mg/kg (gavage). The antioxidant treatment protected the lungs from stress in the first 12 h, but significant oxidative stress induction was observed at the 24-hour time point, and, after 48 h, there was no protection exerted by the antioxidant treatment. NAC (N-acetylcysteine) reversed the elastance parameters, and ΔP1 and ΔP2 compared with 24 h LPS alone. NAC reduced the number of inflammatory cells in histology analysis when compared with the 24 h LPS alone-treated group. NAC also inhibited the transcription of NFκB, IL-6, TNF-α and COX2 usually induced by LPS. Our results suggest that oxidative stress plays an important role in structural, functional and inflammatory responses in the ALI model.

Effects of the flavonoid casticin from Brazilian Croton betulaster in cerebral cortical progenitors in vitro: direct and indirect action through astrocytes.

Neurodegenerative diseases are a major constraint on the social and economic development of many countries. Evidence has suggested that phytochemicals have an impact on brain pathology; however, both their mechanisms of action and their cell targets are incompletely known. Here, we investigated the effects of the flavonoid casticin, extracted from Croton betulaster, a common plant in the state of Bahia in Brazil, on rat cerebral cortex neurons in vitro. Treatment of neural progenitors with 10 microM casticin increased the neuronal population positive for the neuronal marker beta-tubulin III and the neuronal transcriptional factor Tbr2 by approximately 20%. This event was followed by a 50% decrease in neuronal death. Pools of astrocyte (GFAP and S100beta), neural (nestin), and oligodendrocyte (Olig2 and NG2) progenitors were not affected by casticin. Neither neuronal commitment nor proliferation of progenitors was affected by casticin, suggesting a neuroprotective effect of this compound. Culture of neural progenitors on casticin-treated astrocyte monolayers increased the neuronal population by 40%. This effect was reproduced by conditioned medium derived from casticin-treated astrocytes, suggesting the involvement of a soluble factor. ELISA assays of the conditioned medium revealed a 20% increase in interleukin-6 level in response to casticin. In contrast to the direct effect, neuronal death was unaffected, but a 52% decrease in the death of nestin-positive progenitors was observed. Together our data suggest that casticin influences the neuronal population by two mechanisms: 1) directly, by decreasing neuronal death, and 2) indirectly, via astrocytes, by modulating the pool of neuronal progenitors.

CCR2 receptor is essential to activate microbicidal mechanisms to control Toxoplasma gondii infection in the central nervous system.

Chemokines comprise a structurally related family of cytokines that regulate leukocyte trafficking. Because infection with Toxoplasma gondii can induce an important inflammatory reaction that, if left uncontrolled, can lead to death, we investigated the role of the chemokine receptor CCR2 in T. gondii infection. We orally infected CCR2(-/-) mice with five ME-49 T. gondii cysts and monitored morbidity, survival, and immune response thereafter. The CCR2(-/-) mice displayed higher susceptibility to infection as all mice died on day 28 after infection. Despite similar Th1 responses, a more evident anti-inflammatory response was induced in the peripheral organs of CCR2(-/-) mice compared with wild-type C57BL/6 mice. Additionally, CCR2(-/-) mice presented greater parasitism and a milder inflammatory reaction in their peripheral organs with lesser CD4(+) and MAC-1(+) and greater CD8(+) cell migration. The parasite load decreased in these organs in CCR2(-/-) mice but remained uncontrolled in the central nervous system. Additionally, we observed down-regulated inducible nitric oxide synthase expression in peripheral organs from CCR2(-/-) mice that was associated with a small nitric oxide production by spleen macrophages. In conclusion, in the absence of CCR2, another mechanism is activated to control tissue parasitism in peripheral organs. Nevertheless, CCR2 is essential for the activation of microbicidal mediators that control T. gondii replication in the central nervous system.

A critical role of leukotriene B4 in neutrophil migration to infectious focus in cecal ligaton and puncture sepsis.

Neutrophil migration to an infectious focus is essential for control and resolution of infection. Early studies demonstrated that the failure of such migration is observed in lethal sepsis induced by cecal ligation and puncture (L-CLP), whereas intense neutrophil migration is seen in sublethal CLP (SL-CLP). In this study, we found that inhibition of synthesis of prostaglandins or leukotriene B4 (LTB4) did not modify the failure of neutrophil migration or the survival rate of L-CLP mice. In addition, pretreatment of L-CLP mice with a platelet activating factor (PAF) receptor antagonist (UK74505), despite not interfering with the failure process, significantly increased (33%) the survival rate of the animals. Inhibitors of prostaglandin synthesis (indomethacin and meloxican) and UK74505 did not modify the neutrophil migration observed in SL-CLP. On the other hand, the blockade of LTB4 synthesis (MK886, a 5-lipoxygenase-activating protein inhibitor) or of its receptors (CP-105,696) resulted in reduced neutrophil migration to the peritoneal cavity in SL-CLP mice (62% and 60%, respectively), a consequent increase in the number of bacteria in the inflammatory focus, and a reduced survival rate of the animals (43% and 38%, respectively). Both SL-CLP and L-CLP animals presented significant levels of LTB4 in the peritoneal exudate (3- and 8-fold higher than sham group, respectively) and these were reduced by the pretreatment of mice with LTB4 inhibitors. In conclusion, our results suggest that LTB4, but not prostaglandins or PAF, is an important chemoattractant involved in neutrophil recruitment to infection sites in SL-CLP, a crucial event in confining the invading pathogens to a restricted area. However, in circumstances in which the infection turns to a lethal sepsis, LTB4 is not involved in the observed failure of neutrophil migration to the infectious focus.