IL-1R1/MyD88 signaling is critical for elastase-induced lung inflammation and emphysema.

Lung emphysema and fibrosis are severe complications of chronic obstructive pulmonary disease, and uncontrolled protease activation may be involved in the pathogenesis. Using experimental elastase-induced acute inflammation, we demonstrate here that inflammation and development of emphysema is IL-1R1 and Toll/IL-1R signal transduction adaptor MyD88 dependent; however, TLR recognition is dispensable in this model. Elastase induces IL-1beta, TNF-alpha, keratinocyte-derived chemokine, and IL-6 secretion and neutrophil recruitment in the lung, which is drastically reduced in the absence of IL-1R1 or MyD88. Further, tissue destruction with emphysema and fibrosis is attenuated in the lungs of IL-1R1- and MyD88-deficient mice. Specific blockade of IL-1 by IL-1R antagonist diminishes acute inflammation and emphysema. Finally, IL-1beta production and inflammation are reduced in mice deficient for the NALP3 inflammasome component apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), and we identified uric acid, which is produced upon elastase-induced lung injury, as an activator of the NALP3/ASC inflammasome. In conclusion, elastase-mediated lung pathology depends on inflammasome activation with IL-1beta production. IL-1beta therefore represents a critical mediator and a possible therapeutic target of lung inflammation leading to emphysema.

Local and remote tissue injury upon intestinal ischemia and reperfusion depends on the TLR/MyD88 signaling pathway.

Innate immune responses against microorganisms may be mediated by Toll-like receptors (TLRs). Intestinal ischemia-reperfusion (i-I/R) leads to the translocation of bacteria and/or bacterial products such as endotoxin, which activate TLRs leading to acute intestinal and lung injury and inflammation observed upon gut trauma. Here, we investigated the role of TLR activation by using mice deficient for the common TLR adaptor protein myeloid differentiation factor 88 (MyD88) on local and remote inflammation following intestinal ischemia. Balb/c and MyD88(-/-) mice were subjected to occlusion of the superior mesenteric artery (45 min) followed by intestinal reperfusion (4 h). Acute neutrophil recruitment into the intestinal wall and the lung was significantly diminished in MyD88(-/-) after i-I/R, which was confirmed microscopically. Diminished neutrophil recruitment was accompanied with reduced concentration of TNF-alpha and IL-1beta level. Furthermore, diminished microvascular leak and bacteremia were associated with enhanced survival of MyD88(-/-) mice. However, neither TNF-alpha nor IL-1beta neutralization prevented neutrophil recruitment into the lung but attenuated intestinal inflammation upon i-I/R. In conclusion, our data demonstrate that disruption of the TLR/MyD88 pathway in mice attenuates acute intestinal and lung injury, inflammation, and endothelial damage allowing enhanced survival.

Toll-like receptor and tumour necrosis factor dependent endotoxin-induced acute lung injury.

Recent studies on endotoxin/lipopolysaccharide (LPS)-induced acute inflammatory response in the lung are reviewed. The acute airway inflammatory response to inhaled endotoxin is mediated through Toll-like receptor 4 (TLR4) and CD14 signalling as mice deficient for TLR4 or CD14 are unresponsive to endotoxin. Acute bronchoconstriction, tumour necrosis factor (TNF), interleukin (IL)-12 and keratinocyte-derived chemokine (KC) production, protein leak and neutrophil recruitment in the lung are abrogated in mice deficient for the adaptor molecules myeloid differentiation factor 88 (MyD88) and Toll/Interleukin-1 receptor (TIR)-domain-containing adaptor protein (TIRAP), but independent of TIR-domain-containing adaptor-inducing interferon-beta (TRIF). In particular, LPS-induced TNF is required for bronchoconstriction, but dispensable for inflammatory cell recruitment. Lipopolysaccharide induces activation of the p38 mitogen-activated protein kinase (MAPK). Inhibition of pulmonary MAPK activity abrogates LPS-induced TNF production, bronchoconstriction, neutrophil recruitment into the lungs and broncho-alveolar space. In conclusion, TLR4-mediated, bronchoconstriction and acute inflammatory lung pathology to inhaled endotoxin are dependent on TLR4/CD14/MD2 expression using the adapter proteins TIRAP and MyD88, while TRIF, IL-1R1 or IL-18R signalling pathways are dispensable. Further downstream in this axis of signalling, TNF blockade reduces only acute bronchoconstriction, while MAPK inhibition abrogates completely endotoxin-induced inflammation.

Lymphatic-borne IL-1beta and the inducible isoform of nitric oxide synthase trigger the bronchial hyporesponsiveness after intestinal ischema/reperfusion in rats.

Intestinal I/R (i-I/R) is an insult associated to further adult respiratory distress syndrome and multiple organ failure. This study was designed to evaluate the repercussions of i-I/R on bronchial reactivity to the cholinergic agent methacholine. Anesthetized rats were subjected to superior mesenteric artery occlusion (45 min) and killed after clamp release and defined intestinal reperfusion periods (30 min, 2, 4, or 24 h). Intestinal I/R caused a progressive bronchial hyporesponsiveness (BHR) that was maximal upon 2 h but reverted within 24 h of intestinal reperfusion. The BHR observed at 2-h i-I/R was prevented by NOS inhibitors (N-L-nitroarginine methyl ester and aminoguanidine) or the KATP channel blocker glibenclamide. Moreover, 2-h i-I/R increased the pulmonary iNOS mRNA expression, a fact prevented by lymphatic thoracic duct ligation. The methacholine reactivity of 2-h i-I/R bronchial segments incubated with NOS inhibitors or glibenclamide was similar to that of naive tissues. In vivo blockade of IL-1beta receptors or lymphatic duct ligation before 2-h i-I/R both abolished BHR. Incubation of naive bronchial segments with lymph collected from 2-h i-I/R rats determined BHR, an effect fully preventable by ex vivo blockade of IL-1beta receptors. Incubation of naive bronchial segments with IL-1beta, but not with IL-10 or TNF-alpha, significantly induced BHR that was prevented by N-L-nitroarginine methyl ester. Our data suggest that a gut ischemic insult generates IL-1beta that, upon reperfusion, travels through the lymph into the lungs. In this tissue, IL-1beta would stimulate the generation of NO that orchestrates the ensuing BHR for which the opening of KATP channels seems to play a pivotal role.

Diagnostic methods in sepsis: the need of speed.

OBJECTIVE: Sepsis is a common condition encountered in hospital environments. There is no effective treatment for sepsis, and it remains an important cause of death at intensive care units. This study aimed to discuss some methods that are available in clinics, and tests that have been recently developed for the diagnosis of sepsis. METHODS: A systematic review was performed through the analysis of the following descriptors: sepsis, diagnostic methods, biological markers, and cytokines. RESULTS: The deleterious effects of sepsis are caused by an imbalance between the invasiveness of the pathogen and the ability of the host to mount an effective immune response. Consequently, the host's immune surveillance fails to eliminate the pathogen, allowing it to spread. Moreover, there is a pro-inflammatory mediator release, inappropriate activation of the coagulation and complement cascades, leading to dysfunction of multiple organs and systems. The difficulty achieve total recovery of the patient is explainable. There is an increased incidence of sepsis worldwide due to factors such as aging population, larger number of surgeries, and number of microorganisms resistant to existing antibiotics. CONCLUSION: The search for new diagnostic markers associated with increased risk of sepsis development and molecules that can be correlated to certain steps of sepsis is becoming necessary. This would allow for earlier diagnosis, facilitate patient prognosis characterization, and prediction of possible evolution of each case. All other markers are regrettably constrained to research units.

Tumor necrosis factor is not associated with intestinal ischemia/reperfusion-induced lung inflammation.

Intestinal ischemia-reperfusion (I/R) injury may cause acute systemic and lung inflammation. Here, we revisited the role of TNF-alpha in an intestinal I/R model in mice, showing that this cytokine is not required for the local and remote inflammatory response upon intestinal I/R injury using neutralizing TNF-alpha antibodies and TNF ligand-deficient mice. We demonstrate increased neutrophil recruitment in the lung as assessed by myeloperoxidase activity and augmented IL-6, granulocyte colony-stimulating factor, and KC levels, whereas TNF-alpha levels in serum were not increased and only minimally elevated in intestine and lung upon intestinal I/R injury. Importantly, TNF-alpha antibody neutralization neither diminished neutrophil recruitment nor any of the cytokines and chemokines evaluated. In addition, the inflammatory response was not abrogated in TNF and TNF receptors 1 and 2-deficient mice. However, in view of the damage on the intestinal barrier upon intestinal I/R with systemic bacterial translocation, we asked whether Toll-like receptor (TLR) activation is driving the inflammatory response. In fact, the inflammatory lung response is dramatically reduced in TLR2/4-deficient mice, confirming an important role of TLR receptor signaling causing the inflammatory lung response. In conclusion, endogenous TNF-alpha is not or minimally elevated and plays no role as a mediator for the inflammatory response upon ischemic tissue injury. By contrast, TLR2/4 signaling induces an orchestrated cytokine/chemokine response leading to local and remote pulmonary inflammation, and therefore disruption of TLR signaling may represent an alternative therapeutic target.

Nitric oxide mediates lung vascular permeability and lymph-borne IL-6 after an intestinal ischemic insult.

Acute lung injury following intestinal I/R depends on neutrophil-endothelial cell interactions and on cytokines drained from the gut through the lymph. Among the mediators generated during I/R, increased serum levels of IL-6 and NO are also found and might be involved in acute lung injury. Once intestinal ischemia itself may be a factor of tissue injury, in this study, we investigated the presence of IL-6 in lymph after intestinal ischemia and its effects on human umbilical vein endothelial cells (HUVECs) detachment. The involvement of NO on the increase of lung and intestinal microvascular permeability and the lymph effects on HUVEC detachment were also studied. Upon anesthesia, male Wistar rats were subjected to occlusion of the superior mesenteric artery during 45 min, followed by 2-h intestinal reperfusion. Rats were treated with the nonselective NO synthase (NOS) inhibitor L-NAME (N(omega)-nitro-L-arginine methyl ester) or with the selective inhibitor of iNOS aminoguanidine 1 h before superior mesenteric artery occlusion. Whereas treatment with L-NAME during ischemia increased both IL-6 levels in lymph and lung microvascular permeability, aminoguanidine restored the augmented intestinal plasma extravasation due to ischemia and did not induce IL-6 in lymph. On the other hand, IL-6 and lymph of intestinal I/R detached the HUVECs, whereas lymph of ischemic rats upon L-NAME treatment when incubated with anti-IL-6 prevented HUVEC detachment. It is shown that the intestinal ischemia itself is sufficient to increase intestinal microvascular permeability with involvement of iNOS activation. Intestinal ischemia and absence of constitutive NOS activity leading to additional intestinal stress both cause release of IL-6 and increase of lung microvascular permeability. Because anti-IL-6 prevented the endothelial cell injury caused by lymph at the ischemia period, the lymph-borne IL-6 might be involved with endothelial cell activation. At the reperfusion period, this cytokine does not seem to be modulated by NO.

Diagnostic methods in sepsis: the need of speed

OBJECTIVE: Sepsis is a common condition encountered in hospital environments. There is no effective treatment for sepsis, and it remains an important cause of death at intensive care units. This study aimed to discuss some methods that are available in clinics, and tests that have been recently developed for the diagnosis of sepsis. METHODS: A systematic review was performed through the analysis of the following descriptors: sepsis, diagnostic methods, biological markers, and cytokines. RESULTS: The deleterious effects of sepsis are caused by an imbalance between the invasiveness of the pathogen and the ability of the host to mount an effective immune response. Consequently, the host's immune surveillance fails to eliminate the pathogen, allowing it to spread. Moreover, there is a pro-inflammatory mediator release, inappropriate activation of the coagulation and complement cascades, leading to dysfunction of multiple organs and systems. The difficulty achieve total recovery of the patient is explainable. There is an increased incidence of sepsis worldwide due to factors such as aging population, larger number of surgeries, and number of microorganisms resistant to existing antibiotics. CONCLUSION: The search for new diagnostic markers associated with increased risk of sepsis development and molecules that can be correlated to certain steps of sepsis is becoming necessary. This would allow for earlier diagnosis, facilitate patient prognosis characterization, and prediction of possible evolution of each case. All other markers are regrettably constrained to research units.

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.