Natália Vasconcelos Casquilho

LASSBio 596 per os avoids pulmonary and hepatic inflammation induced by microcystin-LR

Cyanobacterial blooms that generate microcystins (MCYSTs) are increasingly recognized as an important health problem in aquatic ecosystems. We have previously reported the impairment of pulmonary structure and function by microcystin-LR (MCYST-LR) exposure as well as the pulmonary improvement by intraperitoneally injected (i.p.) LASSBio 596. In the present study, we aimed to evaluate the usefulness of LASSBio 596 per os on the treatment of pulmonary and hepatic injuries induced by MCYST-LR. Swiss mice received an intraperitoneal injection of 40 μl of saline (CTRL) or a sub-lethal dose of MCYST-LR (40 μg/kg). After 6 h the animals received either saline (TOX and CTRL groups) or LASSBio 596 (50 mg/kg, LASS group) by gavage. Eight hours after the first instillation, lung impedance (static elastance, elastic component of viscoelasticity and resistive, viscoelastic and total pressures) was determined by the end-inflation occlusion method. Left lung and liver were prepared for histology. In lung and hepatic homogenates MCYST-LR, TNF-α, IL-1β and IL-6 were determined by ELISA. LASSBio 596 per os (LASS mice) kept all lung mechanical parameters, polymorphonuclear (PMN) cells, pro-inflammatory mediators, and alveolar collapse similar to control mice (CTRL), whereas in TOX these findings were higher than CTRL. Likewise, liver structural deterioration (hepatocytes inflammation, necrosis and steatosis) and inflammatory process (high levels of pro-inflammatory mediators) were less evident in the LASS than TOX group. LASS and CTRL did not differ in any parameters studied. In conclusion, orally administered LASSBio 596 prevented lung and hepatic inflammation and completely blocked pulmonary functional and morphological changes induced by MCYST-LR.

Ventilação mecânica com baixo volume corrente e estresse oxidativo em pulmões saudáveis de camundongos

Objective: Mechanical ventilation (MV) itself can directly contribute to lung injury. Therefore, the aim of the present study was to investigate early biomarkers concerning oxidant/antioxidant balance, oxidative stress, and inflammation caused by short-term MV in healthy mouse lungs. Methods: Twenty male C57BL/6 mice were randomly divided into two groups: MV, submitted to low tidal volume (V T , 6 mL/kg) MV for 30 min; and spontaneous respiration (SR), used as controls. Lung homogenate samples were tested regarding the activity of various antioxidant enzymes, lipid peroxidation, and TNF-α expression. Results: In comparison with the SR group, the MV group showed a significant decrease in the activity of superoxide dismutase (≈35%; p < 0.05), together with an increase in the activity of catalase (40%; p < 0.01), glutathione peroxidase (500%; p < 0.001), and myeloperoxidase (260%; p < 0.001), as well as a reduction in the glutathione/oxidized glutathione ratio (≈50%; p < 0.05) and an increase in TNF-α expression in the MV group. Oxidative damage, assessed by lipid peroxidation, was also greater in the MV group (45%; p < 0.05). Conclusions: Our results show that short-term low V T MV can directly contribute to lung injury, generating oxidative stress and inflammation in healthy mouse lungs.

Pulmonary and hepatic injury after sub-chronic exposure to sublethal doses of microcystin-LR

We had previously shown that microcystin-LR (MCLR) could induce lung and liver inflammation after acute exposure. The biological outcomes following prolonged exposure to MCLR, although more frequent, are still poorly understood. Thus, we aimed to verify whether repeated doses of MCLR could damage lung and liver and evaluate the dose-dependence of the results. Male Swiss mice received 10 intraperitoneal injections (i.p.) of distilled water (60 μL, CTRL) or different doses of MCLR (5 μg/kg, TOX5), 10 μg/kg (TOX10), 15 μg/kg (TOX15) and 20 μg/kg (TOX20) every other day. On the tenth injection respiratory mechanics (lung resistive and viscoelastic/inhomogeneous pressures, static elastance, and viscoelastic component of elastance) was measured. Lungs and liver were prepared for histology (morphometry and cellularity) and inflammatory mediators (KC and MIP-2) determination. All mechanical parameters and alveolar collapse were significantly higher in TOX5, 10, 15 and 20 than CTRL, but did not differ among them. Lung inflammatory cell content increased dose-dependently in all TOX groups in relation to CTRL, being TOX20 the largest. The production of KC was increased in lung and liver homogenates. MIP-2 increased in the liver of all TOX groups, but in lung homogenates it was significantly higher only in TOX20 group. All TOX mice livers showed steatosis, necrosis, inflammatory foci and a high degree of binucleated hepatocytes. In conclusion, sub-chronic exposure to MCLR damaged lung and liver in all doses, with a more important lung inflammation in TOX20 group.

Lung and liver responses to 1- and 7-day treatments with LASSBio-596 in mice subchronically intoxicated by microcystin-LR

ABSTRACT Microcystin‐LR (MC‐LR) can cause serious injuries upon short‐ and long‐term exposures that can be prevented by LASSBio‐596 (LB‐596), an anti‐inflammatory compound. We aimed to test LB‐596 following subchronic exposure to MC‐LR. Swiss mice received 10 intraperitoneal injections of distilled water (DW) or MC‐LR (20 &mgr;g/kg bw) every 2 days. On the 10th injection animals receiving DW were gavaged with DW or 50 mg/kg bw of LB‐596 for 1 or 7 days (C1D, C7D, CL1D and CL7D groups), whereas those exposed to MC‐LR received either DW or 50 mg/kg of LB‐596 for 1 or 7 days (T1D, T7D, TL1D and TL7D groups). Twelve hours after the last gavage we assessed respiratory mechanics, and extracted lung and liver for histology, apoptosis, inflammatory biomarkers and MC‐LR content. C1D, C7D, CL1D and CL7D were all similar. Mechanical parameters were significantly higher in T1D and T7D compared to the other groups. LB‐596 reversed these changes on day 1 of administration. LB‐596 reduced inflammatory mediators in lung and liver on day 1 of treatment. On day 7 apoptosis in liver and lung fell even more. Briefly, 7‐day administration completely reversed lung and liver changes. HighlightsThe effects of LASSBio‐596 were evaluated in a subchronic model of intoxication by microcystin‐LR (MC‐LR).MC‐LR induced lung and liver deterioration.One‐day treatment with LASSBio‐596 was effective to improve lung mechanics and inflammation.Seven‐day treatment with LASSBio‐596 reverted lung and liver apoptosis and hepatic inflammation.

Oxidative imbalance in mice intoxicated by microcystin-LR can be minimized

&NA; Microcystins‐LR (MC‐LR) is a cyanotoxin produced by cyanobacteria. We evaluated the antioxidant potential of LASSBio‐596 (LB‐596, inhibitor of phosphodiesterases 4 and 5), per os, and biochemical markers involved in lung and liver injury induced by exposure to sublethal dose of MC‐LR. Fifty male Swiss mice received an intraperitoneal injection of 60 &mgr;L of saline (CTRL group, n = 20) or a sublethal dose of MC‐LR (40 &mgr;g/kg, TOX group, n = 20). After 6 h the animals received either saline (TOX and CTRL groups) or LB‐596 (50 mg/kg, TOX + LASS group, n = 10) by gavage. At 6 h after exposure, respiratory mechanics was evaluated in 10 CTRL and 10 TOX mice: there was a significant increase of all lung mechanics parameters (static elastance, viscoelastic component of elastance and lung resistive and viscoelastic/inhomogeneous pressures) in TOX compared to CTRL. 8 h after saline or MC‐LR administration, i.e., 2 h after treatment with LB‐596, blood serum levels of alanine aminotransferase and aspartate aminotransferase, activity of superoxide dismutase, catalase, and content of malondialdehyde and carbonyl in lung and liver, NADPH oxidase 2 and 4 mRNA expressions, dual oxidase enzyme activity and H2O2 generation were analyzed in lung homogenates. All parameters were significantly higher in TOX than in the other groups. There was no significant difference between CTRL and TOX + LASS. MC‐LR deteriorated lung and liver functions and induced redox imbalance in them, which was prevented by oral administration of LB‐596. HighlightsThe effects of LASSBio 596 (LB‐596) per os were evaluated in an acute model of intoxication by microcystin‐LR (MC‐LR).MC‐LR impaired lung and liver functions, as well as produced oxidative stress and damage.Treatment with LB‐596 improved lung and liver oxidative stress and damage and recovered liver function.

2,2'-Azobis (2-Amidinopropane) Dihydrochloride Is a Useful Tool to Impair Lung Function in Rats.

Recently, several studies have reported that respiratory disease may be associated with an increased production of free radicals. In this context, 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH) is a free radical-generating compound widely used to mimic the oxidative stress state. We aimed to investigate whether AAPH can generate lung functional, inflammatory, histological and biochemical impairments in the lung. Wistar rats were divided into five groups and instilled with saline solution (714 μL/kg, CTRL group) or different amounts of AAPH (25, 50, 100, and 200 mg/kg, 714 μL/kg, AAPH groups). Seventy-two hours later the animals were anesthetized, paralyzed, intubated and static elastance (Est), viscoelastic component of elastance (ΔE), resistive (ΔP1) and viscoelastic (ΔP2) pressures were measured. Oxidative damage, inflammatory markers and lung morphometry were analyzed. ΔP1 and Est were significantly higher in AAPH100 and AAPH200 than in the other groups. The bronchoconstriction indexes were larger in AAPH groups than in CTRL. The area occupied by collagen and elastic fibers, polymorpho- and mononuclear cells, malondialdehyde and carbonyl groups levels were significantly higher in AAPH200 than in CTRL. In comparison to CTRL, AAPH200 showed significant decrease and increase in the activities of superoxide dismutase and catalase, respectively. AAPH augmented the release of pro-inflammatory cytokines IL-1β, IL-6 e TNF-α. Hence, exposure to AAPH caused significant inflammatory alterations and redox imbalance accompanied by altered lung mechanics and histology. Furthermore, we disclosed that exposure to AAPH may represent a useful in vivo tool to trigger lung lesions.