Methylene blue protects against paraquat-induced acute lung injury in rats

Spectroscopic Measurement of Methylene Blue Distribution in Organs and Tissues of Hamadryas Baboons during Oral Administration

New research on Methylene Blue (MB), carried out in 2020, shows that it can be an effective antiviral drug as part of COVID-19 treatment. According to the research findings, MB has potential as a direct antiviral drug for the prevention and treatment of COVID-19 in the first stages of the disease. However, the MB accumulation by various types of tissues, as well as by immune cells, has not been previously studied. Therefore, the objective of this study was to obtain spectral data on the interstitial distribution of the administered drug in endothelial tissues in primates. The data on interstitial MB distribution obtained by spectroscopic measurement at both macro- and microlevels during oral administration to Hamadryas baboon individuals demonstrate that MB accumulates in mucous membranes of gastrointestinal tract and the tissues of the respiratory, cardiovascular, immune, and nervous systems. Additionally, it was found that MB was present in lung and brain myeloid cells in significant concentrations, which makes it potentially useful for protection from autoimmune response (cytokine storm) and as a tool for the correction of immunocompetent cells’ functional state during laser irradiation. Since the cytokine storm starts from monocytic cells during SARS-CoV-2 cellular damage and since tumor-associated macrophages can significantly alter tumor metabolism, accumulation of MB in these cells provides a reason to conclude that the immune response correction in COVID-19 patients and change in macrophages phenotype can be achieved by deactivation of inflammatory macrophages in tissues with MB using laser radiation of red spectral range.

Loss of Annexin A5 expression attenuates the lipopolysaccharide-induced inflammatory response of rat alveolar macrophages

Acute lung injury (ALI) is a common respiratory syndrome accompanied with an inflammation response. Annexin A5 (AnxA5) has anti-thrombotic, anti-apoptotic, and anti-inflammatory properties. The current study aims to explore the potential effect of AnxA5 on lipopolysaccharide (LPS)-induced inflammatory response in alveolar macrophages (AMs). Rat AMs (NR8383) were used in this study, and the cell viabilities at 4, 8, and 16 h after LPS administration with gradient concentrations were determined using cell counting kit-8 assay. Cell apoptosis and expressions of messenger RNAs (mRNAs) and protein were determined by flow cytometry, quantitative real-time polymerase chain reaction (qRT-PCR), and western blot, respectively. We found that LPS suppressed the viability of AMs in a dose-dependent manner, and it elevated the expression of AnxA5 in AMs. Inhibition of AnxA5 improved the cell viability compared with the LPS group and could reduce the apoptosis rate in comparison with LPS treatment. The knockdown of AnxA5 suppressed the expressions of tumor necrosis factor-α (TNF-α), interleukin (IL-1β), and IL-6 at both protein and mRNA levels and regulated the expressions of apoptosis-related molecules (Bax, Bcl-2, and caspase-3). Moreover, the knockdown of AnxA5 improved the expression levels of inhibitory κB (IκB) and nuclear factor E2-related factor 2 (Nrf2) but inhibited the expression of nuclear transcription factor κB (NF-κB), compared with the LPS group. SN50 and ML385 were used to validate this signaling, and the inhibition of AnxA5 suppressed the LPS-induced inflammation, indicating that AnxA5 may be a potential anti-inflammatory target. In addition, NF-κB/Nrf2 signaling pathway may also be involved in the LPS-induced inflammatory response of rat alveolar macrophages.

Protective Effects of Chymostatin on Paraquat-Induced Acute Lung Injury in Mice

This study aims to evaluate the role of chymostatin in paraquat-induced acute lung injury. Institute of Cancer Research mice were randomly distributed into the NS, DMSO, chymostatin, paraquat or chymostatin treatment groups. Six mice from each group were intraperitoneally injected with chloral hydrate at 0, 1, 2, 4, 8, 12, 24 and 48 h after treatment administration. Blood samples were collected through cardiac puncture. Lung tissues were stained with haematoxylin and eosin for the observation of lung histology. The degree of pulmonary oedema was determined on the basis of lung wet-to-dry ratio (W/D). The serum activity of cathepsin G was determined through substrate fluorescence assay. The serum levels of endothelial cell-specific molecule-1 (endocan), tumour necrosis factor-a (TNF-a), interleukin-1β (IL-1β), IL-6 and high-mobility group box protein 1 (HMGB1) were determined through enzyme-linked immunosorbent assay. The expression levels of endocan and nuclear NF-κBp65 in the lung were quantified through Western blot. Chymostatin alleviated the pathological changes associated with acute alveolitis in mice; decreased the lung W/D ratio, the activity of cathepsin G and the serum concentrations of TNF-a, IL-1β, IL-6 and HMGB1; and increased the serum concentration of endocan. Western blot results revealed that chymostatin up-regulated endocan expression and down-regulated nuclear NF-κBp65 expression in the lung. Chymostatin reversed the inflammatory effects of paraquat-induced lung injury by inhibiting cathepsin G activity to up-regulate endocan expression and indirectly inhibit NF-κBp65 activity.

Heme oxygnease-1 induction by methylene blue protects RAW264.7 cells from hydrogen peroxide-induced injury

Although methylene blue (MB) has showed strong antioxidant effect, its effect related with heme oxygenase-1 (HO-1) is still unclear. Thus, we investigated the effects of MB on HO-1 protein content and enzyme activity, and its protective effect against hydrogen peroxide (H₂O₂)-induced oxidative damage in RAW264.7 macrophage. The cell viability and the release of lactate dehydrogenase of RAW264.7 were determined. The mitochondrial functions were valuated through these indexes: content of adenosine triphosphate, superoxide dismutase, concentration of reactive oxygen species and mitochondrial membrane potential. Meanwhile, high content screening tested generation of ROS, MMP and intracellular concentration of calcium ion. qRT-PCR valuated macrophage phenotype markers expression. Lastly, flow cytometry and caspase-3 detection analyzed RAW264.7 apoptosis. Our data showed that (1) Both pretreatment and posttreatment of MB increased HO-1 protein content and enzyme activity; (2) MB rescued cells from H₂O₂-induced mitochondrial dysfunction; (3) High content screening revealed that MB alleviated the changes including generation of reactive oxygen species, mitochondrial membrane potential and intracellular concentration of calcium ion in H₂O₂ exposed RAW264.7; (4) MB attenuated H₂O₂-induced apoptosis; (5) MB pretreatment decreased the expression of M1 macrophage markers (Tnf and Nos2) while increasing the expression of M2 macrophage markers (Mrc1 and Il10); (6) The beneficial effect of MB was abolished by zinc protoporphyrin IX (HO-1 activity inhibitor) or HO-1 siRNA. In summary, MB protects RAW264.7 cells from H2O2-induced injury through up-regulation HO-1.

Effects of methylene blue in acute lung injury induced by oleic acid in rats

BACKGROUND

In acute lung injury (ALI), rupture of the alveolar-capillary barrier determines the protein-rich fluid influx into alveolar spaces. Previous studies have reported that methylene blue (MB) attenuates such injuries. This investigation was carried out to study the MB effects in pulmonary capillary permeability.

METHODS

Wistar rats were divided into five groups: (I) Sham: saline bolus; (II) MB, MB infusion for 2 h; (III) oleic acid (OA), OA bolus; (IV) MB/OA, MB infusion for 2 h, and at 5 min after from the beginning, concurrently with an OA bolus; and (V) OA/MB, OA bolus, and after 2 h, MB infusion for 2 h. After 4 h, blood, bronchoalveolar lavage (BAL), and lung tissue were collected from all groups for analysis of plasma and tissue nitric oxide, calculation of the wet weight to dry weight ratio (WW/DW), and histological examination of lung tissue. Statistical analysis was performed using nonparametric test.

RESULTS

Although favourable trends have been observed for permeability improvement parameters (WW/WD and protein), the results were not statistically significant. However, histological analysis of lung tissue showed reduced lesion areas in both pre- and post-treatment groups.

CONCLUSIONS

The data collected using this experimental model was favourable only through macroscopic and histological analysis. These observations are valid for both MB infusions before or after induction of ALI.

Targeting mitochondria with methylene blue protects mice against acetaminophen-induced liver injury

Acetaminophen (APAP) overdose is a frequent cause of drug-induced liver injury and the most frequent cause of acute liver failure in the Western world. Previous studies with mouse models have revealed that impairment of mitochondrial respiration is an early event in the pathogenesis, but the exact mechanisms have remained unclear, and therapeutic approaches to specifically target mitochondria have been insufficiently explored. Here, we found that the reactive oxidative metabolite of APAP, N-acetyl-p-benzoquinoneimine (NAPQI), caused the selective inhibition of mitochondrial complex II activity by >90% in both mouse hepatic mitochondria and yeast-derived complexes reconstituted into nanoscale model membranes, as well as the decrease of succinate-driven adenosine triphosphate (ATP) biosynthesis rates. Based on these findings, we hypothesized that methylene blue (MB), a mitochondria-permeant redox-active compound that can act as an alternative electron carrier, protects against APAP-induced hepatocyte injury. We found that MB (<3 µM) readily accepted electrons from NAPQI-altered, succinate-energized complex II and transferred them to cytochrome c, restoring ATP biosynthesis rates. In cultured mouse hepatocytes, MB prevented the mitochondrial permeability transition and loss of intracellular ATP without interfering with APAP bioactivation. In male C57BL/6J mice treated with APAP (450 mg/kg, intraperitoneally [IP]), MB (10 mg/kg, IP, administered 90 minutes post-APAP) protected against hepatotoxicity, whereas mice treated with APAP alone developed massive centrilobular necrosis and increased serum alanine aminotransferase activity. APAP treatment inhibited complex II activity ex vivo, but did not alter the protein expression levels of subunits SdhA or SdhC after 4 hours.

CONCLUSION

MB can effectively protect mice against APAP-induced liver injury by bypassing the NAPQI-altered mitochondrial complex II, thus alleviating the cellular energy crisis. Because MB is a clinically used drug, its potential application after APAP overdose in patients should be further explored.

Fluorofenidone-loaded PLGA microspheres for targeted treatment of paraquat-induced acute lung injury in rats

Lung-targeting fluorofenidone (AKF) loaded PLGA microspheres (AKF-MS) for the treatment of paraquat (PQ)-induced acute lung injury in rats, were constructed by a solvent evaporation method.

Protective effect of Xuebijing injection on paraquat-induced pulmonary injury via down-regulating the expression of p38 MAPK in rats

Background

Exposure to paraquat results in acute lung injury. A systemic inflammatory response has been widely established as a contributor to paraquat-induced acute lung injury. Recent studies have reported that consumption of Xuebijing prevents inflammatory response-induced diseases. This study investigated whether consumption of Xuebijing protected rats against paraquat-induced acute lung injury.

Methods

Adult male Sprague Dawley rats were randomly divided into four groups: control group; paraquat group; paraquat + Xuebijing group; and paraquat + dexamethasone group. Rats in the paraquat, paraquat + Xuebijing and paraquat + dexamethasone groups were intraperitoneally injected with paraquat (30 mg/kg) or administered paraquat and Xuebijing at 8 mL/kg or dexamethasone at 5 mg/kg, respectively, via an injection into the tail vein. Lung p38 MAPK, NF-κB65, IkB, p-IκB-α, HIF-1α, Nrf2 and TGF-β1 expression were essayed using western blotting. IL-6, TNF-α, IL-1β, IL-10, TGF-β1 and PIIIP were measured using ELISA. ROS, oxidised glutathione and glutathione activity were measured.

Results

After inducing acute lung injury with paraquat for 24 h, Xuebijing was observed to block lung p-p38 MAPK, NF-κB65, HIF-1α, p-IκB-α and TGF-β1 expression, and increased Nrf2 and IkB expression. The numbers of neutrophils and lymphocytes and total number of cells were significantly lower in the Xuebijing group compared with the control group. IL-6, TNF-α, IL-1β, TGF-β1 and PIIIP levels were significantly decreased in the Xuebijing group. ROS and oxidised glutathione activity were markedly inhibited by Xuebijing. Histological evaluation showed attenuation of the effects of Xuebijing on paraquat-induced lung injury. Compared with the paraquat + dexamethasone group, the Xuebijing + paraquat group showed no significant differences.

Conclusions

Inhibiting the expression of p38 MAPK and NF-κB65 was crucial for the protective effects of Xuebijing on paraquat-induced acute lung injury. The findings suggest that Xuebijing could effectively ameliorate paraquat-induced acute lung injury in rats. Xuebijing was as effective as dexamethasone at improving paraquat-induced lung injury by regulating lung inflammation, lung function and oxidative stress responses.

Protective effects of intranasal curcumin on paraquot induced acute lung injury (ALI) in mice

Paraquot (PQ) is widely and commonly used as herbicide and has been reported to be hazardous as it causes lung injury. However, molecular mechanism underlying lung toxicity caused by PQ has not been elucidated. Curcumin, a known anti-inflammatory molecule derived from rhizomes of Curcuma longa has variety of pharmacological activities including free-radical scavenging properties but the protective effects of curcumin on PQ-induced acute lung injury (ALI) have not been studied. In this study, we aimed to study the effects of curcumin on ALI caused by PQ in male parke's strain mice which were challenged acutely by PQ (50mg/kg, i.p.) with or without curcumin an hour before (5mg/kg, i.n.) PQ intoxication. Lung specimens and the bronchoalveolar lavage fluid (BALF) were isolated for pathological and biochemical analysis after 48h of PQ exposure. Curcumin administration has significantly enhanced superoxide dismutase (SOD) and catalase activities. Lung wet/dry weight ratio, malondialdehyde (MDA) and lactate dehydrogenase (LDH) content, total cell number and myeloperoxidase (MPO) levels in BALF as well as neutrophil infiltration were attenuated by curcumin. Pathological studies also revealed that intranasal curcumin alleviate PQ-induced pulmonary damage and pro-inflammatory cytokine levels like tumor necrosis factor-α (TNF-α) and nitric oxide (NO). These results suggest that intranasal curcumin may directly target lungs and curcumin inhalers may prove to be effective in PQ-induced ALI treatment in near future.