The role of oxidative stress during inflammatory processes

The production of various reactive oxidant species in excess of endogenous antioxidant defense mechanisms promotes the development of a state of oxidative stress, with significant biological consequences. In recent years, evidence has emerged that oxidative stress plays a crucial role in the development and perpetuation of inflammation, and thus contributes to the pathophysiology of a number of debilitating illnesses, such as cardiovascular diseases, diabetes, cancer, or neurodegenerative processes. Oxidants affect all stages of the inflammatory response, including the release by damaged tissues of molecules acting as endogenous danger signals, their sensing by innate immune receptors from the Toll-like (TLRs) and the NOD-like (NLRs) families, and the activation of signaling pathways initiating the adaptive cellular response to such signals. In this article, after summarizing the basic aspects of redox biology and inflammation, we review in detail the current knowledge on the fundamental connections between oxidative stress and inflammatory processes, with a special emphasis on the danger molecule high-mobility group box-1, the TLRs, the NLRP-3 receptor, and the inflammasome, as well as the transcription factor nuclear factor-κ

Pyrrolidine dithiocarbamate administered during ex-vivo lung perfusion promotes rehabilitation of injured donor rat lungs obtained after prolonged warm ischemia.

Damaged lung grafts obtained after circulatory death (DCD lungs) and warm ischemia may be at high risk of reperfusion injury after transplantation. Such lungs could be pharmacologically reconditioned using ex-vivo lung perfusion (EVLP). Since acute inflammation related to the activation of nuclear factor kappaB (NF-κB) is instrumental in lung reperfusion injury, we hypothesized that DCD lungs might be treated during EVLP by pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-κB. Rat lungs exposed to 1h warm ischemia and 2 h cold ischemia were subjected to EVLP during 4h, in absence (CTRL group, N = 6) or in presence of PDTC (2.5g/L, PDTC group, N = 6). Static pulmonary compliance (SPC), peak airway pressure (PAWP), pulmonary vascular resistance (PVR), and oxygenation capacity were determined during EVLP. After EVLP, we measured the weight gain of the heart-lung block (edema), and the concentration of LDH (cell damage), proteins (permeability edema) and of the cytokines IL-6, TNF-α and CINC-1 in bronchoalveolar lavage (BAL), and we evaluated NF-κB activation by the degree of phosphorylation and degradation of its inhibitor IκBα in lung tissue. In CTRL, we found significant NF-κB activation, lung edema, and a massive release of LDH, proteins and cytokines. SPC significantly decreased, PAWP and PVR increased, while oxygenation tended to decrease. Treatment with PDTC during EVLP inhibited NF-κB activation, did not influence LDH release, but markedly reduced lung edema and protein concentration in BAL, suppressed TNFα and IL-6 release, and abrogated the changes in SPC, PAWP and PVR, with unchanged oxygenation. In conclusion, suppression of innate immune activation during EVLP using the NF-κB inhibitor PDTC promotes significant improvement of damaged rat DCD lungs. Future studies will determine if such rehabilitated lungs are suitable for in vivo transplantation

Differential Effects of Total and Partial Neutralization of Tumor Necrosis Factor on Cell-Mediated Immunity to Mycobacterium bovis BCG Infection

The effects of total and partial inhibition of tumor necrosis factor (TNF) on sensitivity to Mycobacterium bovis BCG infection were investigated by using transgenic mice in which hepatocytes produced different amounts of human soluble TNF receptor 1 (sTNFR1) fused to the Fc fragment of human immunoglobulin G3 that could be detected in the serum. Transgenic mice expressing high serum levels of sTNFR1, neutralizing all circulating TNF, failed to develop differentiated granulomas and bactericidal mechanisms, and they succumbed to BCG infection. sTNFR1 transgenic mice did not activate BCG-induced Th1-type cytokines early in infection, but uncontrolled cytokine release was found late in infection. In this work we also evaluated the effect of partial inhibition of TNF on resistance to BCG infection. Transgenic mice expressing low levels of sTNFR1 were protected against BCG infection, and they developed increased bactericidal mechanisms, such as enhanced inducible nitric oxide synthase activity, increased macrophage activation, and showed higher numbers of liver granulomas early in infection compared to their negative littermates. Our data suggest that while total inhibition of TNF prevented BCG-induced cell-mediated immune responses, partial inhibition of TNF could contribute to macrophage activation, induction of bactericidal mechanisms, and granuloma formation in the early phase of BCG infection

Toll-like receptor 5 deficiency exacerbates cardiac injury and inflammation induced by myocardial ischaemia-reperfusion in the mouse

International audienceIn the present study, we report that genetic deletion of toll-like receptor 5 (TLR5) is associated with increased myocardial injury and dysfunction following ischaemia-reperfusion, by enhancing cardiac oxidative stress and p38 activation. TLR5 may thus convey cardioprotective signals during myocardial infarction (MI)

Relationships of basal metabolic rate, relative testis size and cycle length of spermatogenesis in shrews (Mammalia, Soricidae).

The aim of the present study was to determinate the cycle length of spermatogenesis in three species of shrew, Suncus murinus, Sorex coronatus and Sorex minutus, and to assess the relative influence of variation in basal metabolic rate (BMR) and mating system (level of sperm competition) on the observed rate of spermatogenesis, including data of shrew species studied before (Sorex araneus, Crocidura russula and Neomys fodiens). The dynamics of sperm production were determined by tracing 5-bromodeoxyuridine in the DNA of germ cells. As a continuous scaling of mating systems is not evident, the level of sperm competition was evaluated by the significantly correlated relative testis size (RTS). The cycle durations estimated by linear regression were 14.3 days (RTS 0.3%) in Suncus murinus, 9.0 days (RTS 0.5%) in Sorex coronatus and 8.5 days (RTS 2.8%) in Sorex minutus. In regression and multiple regression analyses including all six studied species of shrew, cycle length was significantly correlated with BMR (r2=0.73) and RTS (r2=0.77). Sperm competition as an ultimate factor obviously leads to a reduction in the time of spermatogenesis in order to increase sperm production. BMR may act in the same way, independently or as a proximate factor, revealed by the covariation, but other factors (related to testes size and thus to mating system) may also be involved

Experimental ex vivo lung perfusion with sevoflurane: effects on damaged donor lung grafts

Abstract OBJECTIVES Volatile anaesthetics can provide significant protection against reperfusion injury in various experimental settings. The aim of this study was to assess the potential of sevoflurane treatment, the most commonly used volatile anaesthetic in modern anaesthesia, in rat lungs donated after circulatory death and reconditioned in an ex vivo lung perfusion (EVLP) system. METHODS Fifteen rats were sacrificed and divided into 3 groups. In the control and sevoflurane groups, the heart-lung blocks were exposed to 1 h of warm ischaemia and 2 h of cold ischaemia and were mounted on an EVLP circuit for 3 h, in the absence or in the presence of 2% sevoflurane. In the baseline group, heart-lung blocks were harvested immediately after euthanasia. Physiological data, lung nitro-oxidative stress, lactate dehydrogenase (LDH), expression of cytokines, oedema and histopathological findings were assessed during or post-EVLP. RESULTS The sevoflurane group showed significantly reduced LDH (8.82 ± 3.58 arbitrary unit vs 3.80 ± 3.02 arbitrary unit, P = 0.03), protein carbonyl (1.17 ± 0.44 nmol⋅mg−1 vs 0.55 ± 0.11 nmol⋅mg−1, P = 0.006), 3-nitrotyrosine (197.44 ± 18.47 pg⋅mg−1 vs 151.05 ± 23.54 pg⋅mg−1, P = 0.004), cytokine-induced neutrophil chemoattractant factor 1 (1.17 ± 0.32 ng⋅mg−1 vs 0.66 ± 0.28 ng⋅mg−1, P = 0.03) and tumour necrosis factor alpha (1.50 ± 0.59 vs 0.59 ± 0.38 ng⋅mg−1, P = 0.02) when compared with the control group. In addition, sevoflurane lungs gained significantly less weight (0.72 ± 0.09 g vs 0.72 ± 0.09 g, P = 0.044), had less perivascular oedema (0.58 ± 0.09 vs 0.47 ± 0.07, P = 0.036), and improved static pulmonary compliance (+0.215 ml⋅cmH2O−1, P = 0.003) and peak airways pressure (-1.33 cmH2O, P = 0.04) but similar oxygenation capacity (+1.61 mmHg, P = 0.77) and pulmonary vascular resistances (+0.078 mmHg⋅min⋅ml−1, P = 0.15) when compared with the control group. CONCLUSIONS These findings suggest that the potential of sevoflurane in protecting the lungs donated after cardiac death and reconditioned using EVLP could improve the outcome of these lungs following subsequent transplantation

Static pulmonary compliance and peak airway pressure during EVLP.

<p>Static pulmonary compliance (A) and peak airway pressure (B) were computed 60 minutes after EVLP initiation (baseline values), and every 30 minutes thereafter. CTRL: Ischemia followed by EVLP with Steen® solution alone (N = 6); PDTC: Ischemia followed by EVLP with PDTC treatment (N = 6). Means ± s.e.m. † p < 0.05 vs baseline value; * p<0.05 PDTC vs CTRL (two way ANOVA with Bonferroni’s adjustments for multiples comparisons)</p

Indices of lung edema.

<p>A. Weight gain of the heart-lung blocks expressed in grams, represents the difference between weight of the heart-lung blocks measured before and at the end of EVLP. B. The concentration of proteins in the BAL fluid (in mg^.ml^-1 BAL fluid) was measured as an index of high permeability edema. BASE: BAL fluid and was obtained from normal rats sacrificed without any intervention (Normal, baseline values, N = 3); CTRL: Ischemia followed by EVLP with Steen® solution alone (N = 6); PDTC: Ischemia followed by EVLP with PDTC treatment (N = 6). Means ± s.e.m.* p<0.05 (Heart-lung block weight gain: unpaired <i>t</i> test; Proteins in BAL fluid: ANOVA followed by Tukey’s test).</p

Pulmonary vascular resistance and oxygenation index during EVLP.

<p>Pulmonary vascular resistance (A) was calculated as (mean pulmonary artery pressure - left atrial pressure)/perfusion flow). The oxygenation capacity (B) was calculated as the difference in the partial pressure of O₂ between the effluent and the affluent arms of the EVLP circuits. The vascular resistance and oxygenation capacity were computed after 60 minutes of EVLP (baseline values), and every 30 minutes thereafter. Means ± s.e.m. † p < 0.05 vs baseline value; * p<0.05 PDTC vs CTRL (two way ANOVA with Bonferroni’s adjustments for multiples comparisons).</p