Crotoxin modulates inflammation and macrophages' functions in a murine sepsis model.

Sepsis is a syndrome of physiological and biochemical abnormalities induced by an infection that represents a major public health concern. It involves the early activation of inflammatory responses. Crotoxin (CTX), the major toxin of the South American rattlesnake Crotalus durissus terrificus venom, presents longstanding anti-inflammatory properties. Since immune system modulation may be a strategic target in sepsis management, and macrophages' functional and secretory activities are related to the disease's progression, we evaluated the effects of CTX on macrophages from septic animals. Balb/c male mice submitted to cecal ligation and puncture (CLP) were treated with CTX (0.9 µg/animal, subcutaneously) 1 h after the procedure and euthanized after 6 h. We used plasma samples to quantify circulating cytokines and eicosanoids. Bone marrow differentiated macrophages (BMDM) were used to evaluate the CTX effect on macrophages' functions. Our data show that CTX administration increased the survival rate of the animals from 40% to 80%. Septic mice presented lower plasma concentrations of IL-6 and TNF-α after CTX treatment, and higher concentrations of LXA4, PGE2, and IL-1ß. No effect was observed in IL-10, IFN-γ, and RD1 concentrations. BMDM from septic mice treated with CTX presented decreased capacity of E. coli phagocytosis, but sustained NO and H2O2 production. We also observed higher IL-6 concentration in the culture medium of BMDM from septic mice, and CTX induced a significant reduction. CTX treatment increased IL-10 production by macrophages as well. Our data show that the protective effect of CTX in sepsis mortality involves modulation of macrophage functions and inflammatory mediators' production.

Short-term Obesity Worsens Heart Inflammation and Disrupts Mitochondrial Biogenesis and Function in an Experimental Model of Endotoxemia.

Cardiomyopathy is a well-known complication of sepsis that may deteriorate when accompanied by obesity. To test this hypothesis we fed C57black/6 male mice for 6 week with a high fat diet (60% energy) and submitted them to endotoxemic shock using E. coli LPS (10 mg/kg). Inflammatory markers (cytokines and adhesion molecules) were determined in plasma and heart tissue, as well as heart mitochondrial biogenesis and function. Obesity markedly shortened the survival rate of mouse after LPS injection and induced a persistent systemic inflammation since TNFα, IL-1ß, IL-6 and resistin plasma levels were higher 24 h after LPS injection. Heart tissue inflammation was significantly higher in obese mice, as detected by elevated mRNA expression of pro-inflammatory cytokines (IL-1ß, IL-6 and TNFα). Obese animals presented reduced maximum respiratory rate after LPS injection, however fatty acid oxidation increased in both groups. LPS decreased mitochondrial DNA content and mitochondria biogenesis factors, such as PGC1α and PGC1ß, in both groups, while NRF1 expression was significantly stimulated in obese mice hearts. Mitochondrial fusion/fission balance was only altered by obesity, with no influence of endotoxemia. Obesity accelerated endotoxemia death rate due to higher systemic inflammation and decreased heart mitochondrial respiratory capacity.

Inflammation Precedes Fat Deposition in an Experimental Model of Lymphedema.

Background: Chronic lymphedema is a common complication of lymphatic obstruction, particularly after cancer treatment, characterized by an increased volume of the affected extremity, partly caused by the accumulation of excessive adipose tissue. The relationship between lymph vessels' obstruction and fat deposit is, however, poorly understood. Objective: Our central hypothesis was that the inflammatory process caused by lymph stasis precedes the adipocyte differentiation and fat deposition. Methods and Results: We used a modified mouse tail model to produce secondary lymphedema. Animals were treated with dexamethasone, or the procedure was performed in nitric oxide synthase 2 (NOS2)-deficient mice to evaluate the role of inflammation in lymphedema formation. Adipose tissue (Lipin) and inflammatory markers (IL-6, MCP-1, and F4-80) were analyzed in histological samples and by quantitative polymerase chain reaction. We observed an increased deposition of fat into the affected area that starts 3 weeks after lymph vessel ligation; it further increased after 6 weeks. Genes involved in the inflammatory process were upregulated before adipocyte maturation. Treatment with dexamethasone or the use of inducible nitric oxide synthase knockout mice blocked the inflammatory reaction and inhibited the accumulation of fat distal to the lymphatic obstruction. Conclusion: In the modified mouse tail lymphedema, inflammation precedes adipogenesis. Our data suggest that MCP-1 and nitric oxide may be potential targets for lymphedema management.

Bone Marrow Cells Transplant in Septic Mice Modulates Systemic Inflammatory Response via Cell-Cell Contact.

Sepsis is a dynamic disease, displaying an inflammatory profile that varies over time and for each organ. Controlling the inflammatory response based in targeting a single molecule has been proved useless. We hypothesized that treatment with bone marrow-derived mononuclear cells (BMDMCs) may be more efficient to modulate the systemic inflammatory response to infection. Adult male Balb/c mice were subjected to cecal ligation and puncture (CLP) or endotoxemia model of experimental sepsis. BMDMCs were separated under Ficoll gradient and injected intravenously 1 h after the procedures. Cytokines concentration was quantified in plasma, lungs, heart, and gut. Spleens, lymph nodes, and thymus were used for lymphocytes isolation and cell death assessment. All measurements were performed 2 h after BMDMCs injection. RAW264.7 macrophages and BMDMCs were cocultivated in vitro to investigate the mechanisms involved. Our data showed that an early single intravenous injection of BMDMCs in animals submitted to the murine model of endotoxemia led to the improvement of survival rate; BMDMCs persistency in lung, liver, and spleen after 24 h; decreased necrosis and apoptosis of mononuclear cells; lower TNF-α, but increased IL-10 concentration in plasma; and tissue-specific cytokine profile. In vitro experiments demonstrated that IL-6, IL-10, and nitric oxide production depends on direct contact of BMDMCs to macrophages and that TNF-α production is negatively regulated by PGE2. BMDMCs are efficient in protecting animals from endotoxemia and sepsis, reducing systemic inflammation as well as specifically modulating tissue inflammation, producing the necessary immune regulation to re-equilibrate the inflammatory response.

Low level laser therapy reduces acute lung inflammation without impairing lung function.

Acute lung injury is a condition characterized by exacerbate inflammatory reaction in distal airways and lung dysfunction. Here we investigate the treatment of acute lung injury (ALI) by low level laser therapy (LLLT), an effective therapy used for the treatment of patients with inflammatory disorders or traumatic injuries, due to its ability to reduce inflammation and promote tissue regeneration. However, studies in internal viscera remains unclear. C57BL/6 mice were treated with intratracheal lipopolysaccharide (LPS) (5 mg/kg) or phosphate buffer saline (PBS). Six hours after instillation, two groups were irradiated with laser at 660 nm and radiant exposure of 10 J/cm2 . Intratracheal LPS inoculation induced a marked increase in the number of inflammatory cells in perivascular and alveolar spaces. There was also an increase in the expression and secretion of cytokines (TNF-α, IL-1ß, IL-6,) and chemokine (MCP-1). The LLLT application induced a significant decrease in both inflammatory cells influx and inflammatory mediators secretion. These effects did not affect lung mechanical properties, since no change was observed in tissue resistance or elastance. In conclusion LLLT is able to reduce inflammatory reaction in lungs exposed to LPS without affecting the pulmonary function and recovery.

Endotoxaemic myocardial dysfunction: the role of coronary driving pressure in subendocardial perfusion.

OBJECTIVE: To investigate the role of coronary driving pressure (CDP) in myocardial microcirculatory blood flow during sepsis. We hypothesised that in septic shock there is an impaired autoregulation of microcirculation, and blood flow is totally dependent on CDP. We analysed the effect of lipopolysaccharide (LPS)-induced shock on myocardial microcirculation, separating subendocardial and epicardial areas. We then studied the effect of CDP increases using noradrenaline (NOR) or metaraminol (Aramine [ARA]) on myocardial microcirculation and function, and we analysed the effect of volume infusion on CDP and myocardial function. DESIGN AND SETTING: Endotoxaemia was induced in male Wistar rats by an intraperitoneal injection of LPS 10 mg/kg. Animals were divided into a control (CT) group, an LPS-injected group, and an LPS-injected group treated with saline fluid, NOR or ARA. MAIN OUTCOME MEASURES: Ninety minutes later, a haemodynamic evaluation was performed. NOR or ARA were used to manage the mean arterial pressure (MAP) and CDP, and we inserted a catheter into the left ventricle to measure cardiac parameters. To measure blood flow in the myocardium and other organs, microspheres were introduced into the left ventricle using an infusion pump. RESULTS: After LPS treatment, left ventricular (LV) systolic function (dP/dt max) and diastolic function (dP/dt min) decreased by 34% and 15%, respectively, and load-independent indices (LV contractility in ejection phase and dP/dt max÷end-diastolic volume) were reduced. The CDP was also reduced (by 58%) in the endotoxaemic rats. Myocardial blood flow was reduced (by 80%) in animals with an MAP≤65 mmHg. NOR increased the CDP (LPS, 38 mmHg [SEM, 2 mmHg]; LPS+NOR, 59 mmHg [SEM, 3 mmHg]) and microcirculatory perfusion (LPS, 2 mL/min/g tissue [SEM, 0.6 mL/min/g]; LPS+NOR, 6.2 mL/min/g [SEM, 0.8 mL/min/g]). ARA was also effective in improve microcirculation but saline volume infusion was ineffective in improving CDP or myocardial function. CDP showed a significant correlation with subendocardial blood flow. CONCLUSIONS: Myocardial blood flow in the LV subendocardium and the right ventricle decreases in endotoxaemic rats. Increasing CDP improves myocardial blood flow and function. Thus, in endotoxaemia, microcirculatory blood flow is pressure dependent, suggesting that it may be beneficial to treat patients with sepsis using a higher CDP.

Effect of laser phototherapy on wound healing following cerebral ischemia by cryogenic injury.

Laser phototherapy emerges as an alternative or auxiliary therapy for acute ischemic stroke, traumatic brain injury, degenerative brain disease, spinal cord injury, and peripheral nerve regeneration, but its effects are still controversial. We have previously found that laser phototherapy immunomodulates the response to focal brain damage. Following direct cortical cryogenic injury the effects of laser phototherapy on inflammation and repair was assessed after cryogenic injury (CI) to the central nervous system (CNS) of rats. The laser phototherapy was carried out with a 780 nm AlGaAs diode laser. The irradiation parameters were: power of 40 mW, beam area of 0.04 cm(2), energy density of 3 J/cm(2) (3s) in two points (0.12 J per point). Two irradiations were performed at 3 h-intervals, in contact mode. Rats (20 non-irradiated - controls and 20 irradiated) were used. The wound healing in the CNS was followed in 6 h, 1, 7 and 14 days after the last irradiation. The size of the lesions, the neuron cell viability percentages and the amount of positive GFAP labeling were statistically compared by ANOVA complemented by Tukey's test (p<0.05). The distribution of lymphocytes, leukocytes and macrophages were also analyzed. CI created focal lesions in the cortex represented by necrosis, edema, hemorrhage and inflammatory infiltrate. The most striking findings were: lased lesions showed smaller tissue loss than control lesions in 6 h. During the first 24 h the amount of viable neurons was significantly higher in the lased group. There was a remarkable increase in the amount of GFAP in the control group by 14 days. Moreover, the lesions of irradiated animals had fewer leukocytes and lymphocytes in the first 24 h than controls. Considering the experimental conditions of this study it was concluded that laser phototherapy exerts its effect in wound healing following CI by controlling the brain damage, preventing neuron death and severe astrogliosis that could indicate the possibility of a better clinical outcome.

B-1 cells temper endotoxemic inflammatory responses.

Sepsis syndrome is caused by inappropriate immune activation due to bacteria and bacterial components released during infection. This syndrome is the leading cause of death in intensive care units. Specialized B-lymphocytes located in the peritoneal and pleural cavities are known as B-1 cells. These cells produce IgM and IL-10, both of which are potent regulators of cell-mediated immunity. It has been suggested that B-1 cells modulate the systemic inflammatory response in sepsis. In this study, we conducted in vitro and in vivo experiments in order to investigate a putative role of B-1 cells in a murine model of LPS-induced sepsis. Macrophages and B-1 cells were studied in monocultures and in co-cultures. The B-1 cells produced the anti-inflammatory cytokine IL-10 in response to LPS. In the B-1 cell-macrophage co-cultures, production of proinflammatory mediators (TNF-α, IL-6 and nitrite) was lower than in the macrophage monocultures, whereas that of IL-10 was higher in the co-cultures. Co-culture of B-1 IL-10(-/-) cells and macrophages did not reduce the production of the proinflammatory mediators (TNF-α, IL-6 and nitrite). After LPS injection, the mortality rate was higher among Balb/Xid mice, which are B-1 cell deficient, than among wild-type mice (65.0% vs. 0.0%). The Balb/Xid mice also presented a proinflammatory profile of TNF-α, IL-6 and nitrite, as well as lower levels of IL-10. In the early phase of LPS stimulation, B-1 cells modulate the macrophage inflammatory response, and the main molecular pathway of that modulation is based on IL-10-mediated intracellular signaling.