Fernando Rodrigues Coelho

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-1β, TNF-α, 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-1β 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-1β production. IL-1β therefore represents a critical mediator and a possible therapeutic target of lung inflammation leading to emphysema.

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&ohgr;-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.

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-&agr; 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-&agr; 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-&agr; levels in serum were not increased and only minimally elevated in intestine and lung upon intestinal I/R injury. Importantly, TNF-&agr; 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-&agr; 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.

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 hosts 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.

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 (Nω-L-nitroarginine methyl ester and aminoguanidine) or the K+ATP 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-1β 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-1β receptors. Incubation of naive bronchial segments with IL-1β, but not with IL-10 or TNF-α, significantly induced BHR that was prevented by Nω-L-nitroarginine methyl ester. Our data suggest that a gut ischemic insult generates IL-1β that, upon reperfusion, travels through the lymph into the lungs. In this tissue, IL-1β would stimulate the generation of NO that orchestrates the ensuing BHR for which the opening of K+ATP channels seems to play a pivotal role.

Oxidation of the tryptophan 32 residue of human superoxide dismutase 1 caused by its bicarbonate-dependent peroxidase activity triggers the non-amyloid aggregation of the enzyme

Background: Protein aggregation is a hallmark of neurodegenerative diseases. Results: Oxidation of the hSOD1-Trp32 residue promotes enzyme covalent dimerization, oligomerization, and aggregation. Conclusion: A novel pathway for hSOD1 aggregation is revealed. Significance: The uniqueness of the Trp32 residue makes its oxidation potentially relevant to ALS pathogenesis. The role of oxidative post-translational modifications of human superoxide dismutase 1 (hSOD1) in the amyotrophic lateral sclerosis (ALS) pathology is an attractive hypothesis to explore based on several lines of evidence. Among them, the remarkable stability of hSOD1WT and several of its ALS-associated mutants suggests that hSOD1 oxidation may precede its conversion to the unfolded and aggregated forms found in ALS patients. The bicarbonate-dependent peroxidase activity of hSOD1 causes oxidation of its own solvent-exposed Trp32 residue. The resulting products are apparently different from those produced in the absence of bicarbonate and are most likely specific for simian SOD1s, which contain the Trp32 residue. The aims of this work were to examine whether the bicarbonate-dependent peroxidase activity of hSOD1 (hSOD1WT and hSOD1G93A mutant) triggers aggregation of the enzyme and to comprehend the role of the Trp32 residue in the process. The results showed that Trp32 residues of both enzymes are oxidized to a similar extent to hSOD1-derived tryptophanyl radicals. These radicals decayed to hSOD1-N-formylkynurenine and hSOD1-kynurenine or to a hSOD1 covalent dimer cross-linked by a ditryptophan bond, causing hSOD1 unfolding, oligomerization, and non-amyloid aggregation. The latter process was inhibited by tempol, which recombines with the hSOD1-derived tryptophanyl radical, and did not occur in the absence of bicarbonate or with enzymes that lack the Trp32 residue (bovine SOD1 and hSOD1W32F mutant). The results support a role for the oxidation products of the hSOD1-Trp32 residue, particularly the covalent dimer, in triggering the non-amyloid aggregation of hSOD1.

New antibacterial agents: Hybrid bioisoster derivatives as potential E. coli FabH inhibitors

The development of resistance to antibiotics by microorganisms is a major problem for the treatment of bacterial infections worldwide, and therefore, it is imperative to study new scaffolds that are potentially useful in the development of new antibiotics. In this regard, we propose the design, synthesis and biological evaluation of hybrid sulfonylhydrazone bioisosters/furoxans with potential antibacterial (Escherichia coli) activity. The most active compound of the series, (E)-3-methyl-4-((2-tosylhydrazono)methyl)-1,2,5-oxadiazole 2-oxide, with a MIC=0.36μM, was not cytotoxic when tested on Vero cells (IC50>100μM). To complement the in vitro screening, we also studied the interaction of the test compounds with β-ketoacyl acyl carrier protein synthase (FabH), the target for the parent compounds, and we observed three important hydrogen-bonding interactions with two important active site residues in the catalytic site of the enzyme, providing complementary evidence to support the target of the new hybrid molecules.

Exposição a hidroquinona e ao fenol sobre a resposta inflamatória pulmonar induzida por bactéria

A gravidade dos efeitos causados pela exposicao ambiental e ocupacional ao benzeno determinou o controle de sua utilizacao. No entanto, mesmo nestas condicoes, toxicidade ao sistema imune e nervoso tem sido descrita. A toxicidade do benzeno e determinada pelos seus produtos de biotransformacao, em que fenol (FE) e hidroquinona (HQ) tem papel relevante na imunotoxicidade. Neste contexto, o presente trabalho mostra que a exposicao 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 reducoes acentuadas no influxo de leucocitos polimorfonucleares (PMN) e mononucleares (MN) para o pulmao 24 horas apos inalacao de Lipopolissacarideo (LPS) de Salmonella abortus. Diferentemente, a migracao de leucocitos em animais expostos ao FE nao foi alterada. A exposicao a ambos os agentes quimicos simultaneamente (dose de 5 mg/kg cada) manteve a reducao na migracao de MN detectada em animais expostos a HQ e potencializou o efeito inibitorio da HQ sobre a migracao de leucocitos PMN. Os prejuizos nas migracoes de leucocitos nao foram decorrentes de modificacoes no numero destas celulas na circulacao. E importante ressaltar que os efeitos foram induzidos por doses dos agentes quimicos que nao causaram prejuizo a funcao hepatica ou renal, determinados pela atividade das transaminases hepaticas e a concentracao de creatinina no soro. Em conjunto, os dados obtidos mostram a exposicao a baixas doses de HQ nao provoca alteracoes nos parâmetros empregados como indicadores de toxicidade. No entanto, os efeitos toxicos sao manifestados resposta do organismo ao trauma.

Cholesterol Secosterol Aldehyde Adduction and Aggregation of Cu,Zn-Superoxide Dismutase: Potential Implications in ALS

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by degeneration of upper and lower motor neurons. While the fundamental causes of the disease are still unclear, the accumulation of Cu,Zn-superoxide dismutase (SOD1) immunoreactive aggregates is associated with familial ALS cases. Cholesterol 5,6-secosterol aldehydes (Seco A and Seco B) are reported to contribute to neurodegenerative disease pathology by inducing protein modification and aggregation. Here we have investigated the presence of secosterol aldehydes in ALS SOD1-G93A rats and their capacity to induce SOD1 aggregation. Secosterol aldehydes were analyzed in blood plasma, spinal cord and motor cortex of ALS rats at the pre-symptomatic and symptomatic stages. Seco B was significantly increased in plasma of symptomatic ALS rats compared to pre-symptomatic animals, suggesting an association with disease progression. In vitro experiments showed that both Seco A and Seco B induce the formation of high molecular weight (HMW) SOD1 aggregates with amorphous morphology. SOD1 adduction to ω-alkynyl-secosterols analyzed by click assay showed that modified proteins are only detected in the HMW region, indicating that secosterol adduction generates species highly prone to aggregate. Of note, SOD1-secosterol adducts containing up to five secosterol molecules were confirmed by MALDI-TOF analysis. Interestingly, mass spectrometry sequencing of SOD1 aggregates revealed preferential secosterol adduction to Lys residues located at the electrostatic loop (Lys 122, 128 and 136) and nearby the dimer interface (Lys 3 and 9). Altogether, our results show that secosterol aldehydes are increased in plasma of symptomatic ALS rats and represent a class of aldehydes that can potentially modify SOD1 enhancing its propensity to aggregate.

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

or IL-1 neutralization on ischemia/reperfusion inducedneutrophil recruitment in the lung and intestine. Balb/c were treatedwith saline, or Anakinra or Enbrel, at 5 and 10 mg/kg twice prior tointestinal ischemia (45 min) followed by reperfusion (4 h). MPOactivity in the lung (a) and intestine (b) was determined as a measureof neutrophil recruitment. Representative data of two independentstudies are given (mean values of 5 mice per group