Montelukast, Leukotriene Inhibitor, Reduces LPS-Induced Acute Lung Inflammation and Human Neutrophil Activation / El montelukast, un inhibidor de leucotrienos, reduce la inflamación pulmonar aguda inducida por LPS y la activación de neutrófilos humanos

Objectives: Some pro-inflammatory lipids derived from 1 lipooxygenase enzyme are potent neutrophil chemoattractant, a cell centrally involved in acute respiratory distress syndrome (ARDS); a syndrome lacking effective treatment. Considering the beneficial effects of the leukotriene receptor inhibitor, montelukast, on other lung diseases, whether montelukast attenuates inflammation in a mouse model of ARDS, and whether it reduces LPS stimulated activation of human neutrophils was investigated. Methods: Thirty-five C57Bl/6 mice were distributed into control (PBS) + 24h, LPS + 24h (10 μg/mouse), control + 48 h, LPS+48 h, and LPS 48 h+Montelukast (10 mg/kg). In addition, human neutrophils were incubated with LPS ( 1μg/mL) and treated with montelukast (10 μM). Results: Oral-tracheal administration of montelukast significantly attenuated total cells (P < .05), macrophages (P < .05), neutrophils (P < .01), lymphocytes (P < .001) and total protein levels in BAL (P < .05), as well as IL-6 (P < .05), CXCL1/KC (P < .05), IL-17 (P < .05) and TNF-alfa (P < .05). Furthermore, montelukast reduced neutrophils (P < .001), lymphocytes (P < .01) and macrophages (P < .01) in the lung parenchyma. In addition, montelukast restored BAL VEGF levels (P < .05). LTB4 receptor expression (P < .001) as well as NF-κB (P <. 001), a downstream target of LPS, were also reduced in lung parenchymal leukocytes. Furthermore, montelukast reduced IL-8 (P < .001) production by LPS-treated human neutrophils. Conclusion: In conclusion, montelukast efficiently attenuated both LPS-induced lung inflammation in a mouse model of ARDS and in LPS challenged human neutrophils

Objetivos: Algunos lípidos proinflamatorios derivados de la enzima lipooxigenasa 1 son potentes quimioatrayentes de neutrófilos, un tipo celular con una implicación principal en el síndrome de distrés respiratorio agudo (SDRA), para el que no hay tratamiento efectivo. Considerando los efectos beneficiosos del inhibidor de los receptores de leucotrienos montelukast en otras enfermedades pulmonares, se investigó si este fármaco era capaz de atenuar la inflamación en un modelo de ratón de SDRA y de reducir la activación de los neutrófilos humanos inducida por LPS. Métodos: Se utilizaron 35 ratones C57BL/6 distribuidos en los siguientes grupos: control (PBS) + 24 h, LPS+(24 h [10 μg/ratón]), control + 48 h y LPS 48 h + montelukast (10 mg/kg). Por otro lado, se incubaron neutrófilos humanos con LPS (1 μg/ml) y se trataron con montelukast (10 μM). Resultados: La administración orotraqueal de montelukast redujo el número total de células (p < 0,05), de macrófagos (p < 0,05), de neutrófilos (p < 0,01), de linfocitos (p < 0,001) y los niveles totales de proteína en el lavado broncoalveolar (p < 0,05), así como de IL-6 (p < 0,05), CXCL1/KC (p < 0,05), IL-17 (p < 0,05) y TNF-alfa (p < 0,05). Además, el montelukast redujo los neutrófilos (p < 0,001), los linfocitos (p < 0,01) y los macrófagos (p < 0,01) en el parénquima pulmonar. Asimismo, restauró los niveles de VEGF en el lavado broncoalveolar (p < 0,05) y disminuyó la expresión del receptor LTB4 (p < 0,001) y de NF-κB (p < 0,001), una diana downstream del LPS, en los leucocitos del parénquima pulmonar. Por último, redujo la producción de IL-8 por parte de los neutrófilos humanos tratados con LPS. Conclusión: En conclusión, el montelukast atenuó de manera eficaz tanto la inflamación pulmonar inducida por LPS en un modelo de ratón de SDRA como en neutrófilos humanos estimulados con LPS

Effects of periodontitis on the development of asthma: The role of photodynamic therapy.

To evaluate whether periodontitis modulates lung inflammation in an experimental model of asthma as well as the photodynamic therapy (PDT) is associated with a reduction of lung inflammation. Seventy-two BALB/c male mice (~2 months) were randomly divided into 8 groups (n = 9): Basal, Periodontitis (P), P+PT, P+PT+PDT, Asthma (A), A+P, A+P+PT, and A+P+PT+PDT. Periodontitis was induced by using the ligature technique and asthma was induced by ovalbumin (OVA). PT was performed with curettes and PDT with methylene blue (0.005%), λ = 660nm, with a radiant exposure of 318J/cm2. After 43 days, euthanasia was carried out prior to lung and mandible morphological analyzes. All of the manipulations of the animals were performed by only one operator. The total and differential cell counts and cytokines IL-4, IL-5, IL-10, IFN-γ, TNF-α, IL-1ß, and IL-6 were evaluated in the bronchoalveolar lavage (BAL) and in the serum. Mucus and alkaline phosphatase were also quantified. Statistical analyzes were performed by a blinded statistician. One-way analysis of variance (ANOVA) was employed, followed by the Student-Newman-Keuls test. Periodontitis group (P) increased alkaline phosphatase and bone resorption (p<0.05), validating the experimental model of periodontitis. The A group and the P group increased the total amount of cells (p <0.05) in the BAL. However, in the A+P group, there was a decrease in these cells, except for in the A+P+PT+PDT group (p<0.05). The asthma group increased the Th2 cytokines and P group increased the Th1 cytokine profile, and A+P+PT+PDT group increased IL-10 cytokine. Mucus was increased for the A and P groups. In conclusion, periodontitis in the asthmatic mice reduced the inflammatory migrated cells in the BAL (eosinophils, lymphocytes, macrophages). In addition, it reduced the levels of the IL-4 and TNF-α cytokines, which was also accompanied by a decreased mucus production. After PDT treatment the total cell count increased however, this increase was not accompanied by a pro-inflammatory cytokines release. Only in PDT group the anti-inflammatory IL-10 was increased. Further studies are needed to understand this mechanism of action.

Aerobic Exercise Reduces Asthma Phenotype by Modulation of the Leukotriene Pathway.

INTRODUCTION: Leukotrienes (LTs) play a central role in asthma. Low- to moderate-intensity aerobic exercise (AE) reduces asthmatic inflammation in clinical studies and in experimental models. This study investigated whether AE attenuates LT pathway activation in an ovalbumin (OVA) model of asthma. METHODS: Sixty-four male, BALB/c mice were distributed into Control, Exercise (Exe), OVA, and OVA + Exe groups. Treadmill training was performed at moderate intensity, 5×/week, 1 h/session for 4 weeks. Quantification of bronchoalveolar lavage (BAL) cellularity, leukocytes, airway remodeling, interleukin (IL)-5, IL-13, cysteinyl leukotriene (CysLT), and leukotriene B4 (LTB4) in BAL was performed. In addition, quantitative analyses on peribronchial leukocytes and airway epithelium for LT pathway agents: 5-lypoxygenase (5-LO), LTA4 hydrolase (LTA4H), CysLT1 receptor, CysLT2 receptor, LTC4 synthase, and LTB4 receptor 2 (BLT2) were performed. Airway hyperresponsiveness (AHR) to methacholine (MCh) was assessed via whole body plethysmography. RESULTS: AE decreased eosinophils (p < 0.001), neutrophils (p > 0.001), lymphocytes (p < 0.001), and macrophages (p < 0.01) in BAL, as well as eosinophils (p < 0.01), lymphocytes (p < 0.001), and macrophages (p > 0.001) in airway walls. Collagen (p < 0.01), elastic fibers (p < 0.01), mucus production (p < 0.01), and smooth muscle thickness (p < 0.01), as well as IL-5 (p < 0.01), IL-13 (p < 0.01), CysLT (p < 0.01), and LTB4 (p < 0.01) in BAL were reduced. 5-LO (p < 0.05), LTA4H (p < 0.05), CysLT1 receptor (p < 0.001), CysLT2 receptor (p < 0.001), LTC4 synthase (p < 0.001), and BLT2 (p < 0.01) expression by peribronchial leukocytes and airway epithelium were reduced. Lastly, AHR to MCh 25 mg/mL (p < 0.05) and 50 mg/mL (p < 0.01) was reduced. CONCLUSION: Moderate-intensity AE attenuated asthma phenotype and LT production in both pulmonary leukocytes and airway epithelium of OVA-treated mice.

Exercise Reduces Lung Fibrosis Involving Serotonin/Akt Signaling.

PURPOSE: Idiopathic pulmonary fibrosis (IPF) is a chronic fibrosing interstitial pneumonia, which involves aberrant serotonin (5-hydroxytryptamine [5-HT]) and Akt signaling. As protective effects of chronic aerobic training (AT) have been demonstrated in the context of lung injury, this study investigated whether AT attenuates bleomycin-induced lung fibrosis partly via a reduction of 5-HT and AKT signaling. METHODS: Seventy-two C57BL/6 male mice were distributed in Control (Co), Exercise (Ex), Fibrosis (Fi), and Fibrosis + Exercise (Fi + Ex) groups. Bleomycin (1.5 UI·kg) was administered on day 1 and treadmill AT began on day 15 and continued for 60 min·d, 5 d·wk for 4 wk. We evaluated total and differential cell counts in bronchoalveolar lavage (BAL), interleukin (IL)-1ß, IL-6, CXCL1/KC, IL-10, tumor necrosis factor α, and transforming growth factor ß levels in BAL, collagen content in lung parenchyma, 5-HT levels in BAL fluid and in serum, the expression of 5-HT2B receptor, and Akt phosphorylation in lung tissue. RESULTS: AT reduced bleomycin-increased number of total cells (P < 0.001), neutrophils (P < 0.01), macrophages (P < 0.01), and lymphocytes (P < 0.05) in BAL. It also reduced the levels of IL-1ß (P < 0.01), IL-6 (P < 0.05), CXCL1/KC (P < 0.001), tumor necrosis factor α (P < 0.001), and transforming growth factor ß (P < 0.001). It increased expression of ant-inflammatory cytokine IL-10 (P < 0.001). It reduced bleomycin-increased 5-HT levels in BAL (P < 0.001) and in serum (P < 0.05). Reductions in collagen fiber deposition (P < 0.01), 5-HT2B receptor expression (P < 0.01), and Akt phosphorylation in lung tissue were observed. CONCLUSIONS: AT accelerates the resolution of lung inflammation and fibrosis in a model of bleomycin-induced lung fibrosis partly via attenuation of 5-HT/Akt signaling.

Exposição a hidroquinona e ao fenol sobre a resposta inflamatória pulmonar induzida por bactéria / Hydroquinone and phenol exposure on pulmonary inflammatory response induced by bacteria

A gravidade dos efeitos causados pela exposição ambiental e ocupacional ao benzeno determinou o controle de sua utilização. No entanto, mesmo nestas condições, toxicidade ao sistema imune e nervoso tem sido descrita. A toxicidade do benzeno é determinada pelos seus produtos de biotransformação, em que fenol (FE) e hidroquinona (HQ) têm papel relevante na imunotoxicidade. Neste contexto, o presente trabalho mostra que a exposição de ratos Wistar, machos, a doses de 5 ou 10 mg/kg de HQ (via i.p., uma vez ao dia, 13 doses consecutivas, com intervalos de 2 dias a cada 5 doses) provocou reduções acentuadas no influxo de leucócitos polimorfonucleares (PMN) e mononucleares (MN) para o pulmão 24 horas após inalação de Lipopolissacarídeo (LPS) de Salmonella abortus. Diferentemente, a migração de leucócitos em animais expostos ao FE não foi alterada. A exposição a ambos os agentes químicos simultaneamente (dose de 5 mg/kg cada) manteve a redução na migração de MN detectada em animais expostos à HQ e potencializou o efeito inibitório da HQ sobre a migração de leucócitos PMN. Os prejuízos nas migrações de leucócitos não foram decorrentes de modificações no número destas células na circulação. É importante ressaltar que os efeitos foram induzidos por doses dos agentes químicos que não causaram prejuízo à função hepática ou renal, determinados pela atividade das transaminases hepáticas e a concentração de creatinina no soro. Em conjunto, os dados obtidos mostram a exposição a baixas doses de HQ não provoca alterações nos parâmetros empregados como indicadores de toxicidade. No entanto, os efeitos tóxicos são manifestados resposta do organismo ao trauma.

The high toxicity induced by occupational and environmental benzene exposure lead to its use restriction. However, at these conditions, neuronal and immune toxicity has been described. It is well known that benzene metabolites, such as hydroxyl compounds phenol (PHE) and hydroquinone (HQ), are responsible for immunotoxicity. In this context, it has shown herein that male Wistar rats exposed to HQ (doses of 5 or 10 mg/kg/day; 13 days with 2-day intervals every 5 doses) presented marked reduction in the number of mononuclear (MN) and polymorphonuclear (PMN) leukocytes in the bronchoalveolar fluid 24 hours after inhalation of Lipopolyssacaride of Salmonella abortus (LPS; 100 µg/mL). On the other hand, leukocyte migration into inflamed lungs was not altered in FE exposed rats, since values obtained were similar to those detected in control animals. Simultaneous exposure to HQ and PHE (5 mg/kg each compound) maintained the decreased number of MN cells observed in HQ exposed rats and potentiated the reduction of PMN cells induced by HQ exposure. The impaired leukocyte migration into inflamed lung did not reflect alterations on number of circulating cells. Moreover, it is important to emphasize that schedule of intoxication did not alter the functional ability of liver and kidney, as detected by normal activity of transaminases and creatinine concentration in the serum. Therefore, it is shown herein that in vivo exposures to lower doses of HQ do not alter end points used as biological indicators of toxicity, nevertheless toxic effects are evident after a host defense.

Lymphatic system as a path underlying the spread of lung and gut injury after intestinal ischemia/reperfusion in rats.

We investigated in rats the influence of the lymphatic system and of tumor necrosis factor (TNF) on the lung inflammation resulting from intestinal ischemia/reperfusion (I/R) performed by 45-min occlusion of the superior mesenteric artery followed by 2 h of reperfusion. A group of rats had the thoracic lymph duct ligated before I/R. In lungs, intestinal I/R evoked a significant neutrophil recruitment, and enhanced microvascular permeability, in addition to generation of TNF in serum. In the gut, there was lowered lactate dehydrogenase (LDH) activity and increased microvascular permeability. Upon lymph duct ligation, I/R rats had a significant reduction of pulmonary neutrophil recruitment and plasma extravasation, in addition to high amounts of TNF in the lymph, contrasting with undetectable levels in the serum. In addition, LDH gut levels in these animals were close to basal values; there was also some (yet significant) reduction of microvascular permeability, suggesting that the ligation of the lymphatic duct exerted some degree of protection against the intestinal injury caused by I/R. In I/R rats, the treatment with pentoxifylline (PTX) reduced TNF in serum and blunted other lung alterations. The gut alterations caused by intestinal I/R were largely blocked by PTX. On the other hand, in I/R rats with lymph duct ligation, PTX exacerbated the reduction of pulmonary neutrophil recruitment, but did not affect pulmonary and intestinal microvascular permeabilities. Similarly, intestinal LDH activity and serum TNF levels were unaffected. Overall, our data show that the pulmonary and gut injuries induced by intestinal I/R are partially dependent on TNF, which is conceivably generated in the injured gut tissue due to intestinal I/R and carried by the lymphatic system. Thus, the mesenteric lymphatic drainage seems to play a role as a path modulator of the pulmonary and intestinal dysfunctions that follow a gut trauma.