Effect of aluminum (Al) speciation on erythrocytic antioxidant defense process: Correlations between lipid membrane peroxidation and morphological characteristics

Aluminum-maltol induced oxidative stress and reduced AMPK activity via BCK-related energy supply failure in C6 cell

Aluminum (Al) exposure significantly interferes with the energy supply in astrocytes, which may be a potential mechanism of Al-induced neurotoxicity. This study was designed to explore the mechanisms of Al-induced energy supply impairment in rat C6 astroglioma cell line. Aluminum-maltolate (Al(mal)3) (0.1 mM, 24 h) exposure significantly decreased brain-type creatine kinase (BCK) co-localization with the endoplasmic reticulum (ER) and resulted in mitochondrial dysfunctions, accompanied by a decrease in AMPK phosphorylation. The results of molecular docking showed that Al(mal)3 increased BCK's hydrophobicity and hindered the localization movement of BCK between subcells·H2O2 co-administration was found to exacerbate mitochondrial dysfunction, Ca2+ dyshomeostasis, and apoptosis. After treated with Al(mal)3, additional oxidative stress contributed to BCK activity inhibition but did not promote a further decrease in AMPK phosphorylation. The activation of p-AMPK by its agonist can partially restore mitochondrial function, BCK activity, and ER-localized-BCK levels in Al(mal)3-treated astrocytes. In summary, Al exposure resulted in a sustained depletion of the mitochondrial and antioxidant systems, which was associated with reduced p-AMPK activity and decreased ER-localized-BCK levels in astrocytes. This study provides a theoretical basis for exploring the mechanisms of neurotoxicity induced by Al exposure.

Chronic Oral Administration of Aluminum Hydroxide Stimulates Systemic Inflammation and Redox Imbalance in BALB/c Mice

The present study is aimed at investigating the long-term effects of the aluminum hydroxide administration in the small intestine, lung, liver, and kidney of male BALB/c mice. The mice received via orogastric gavage phosphate buffered or 10 mg/kg aluminum hydroxide 3 times a week for 6 months. Administration of aluminum hydroxide decreased hemoglobin, hematocrit, and erythrocyte. In the blood, kidney and liver function markers were evaluated, and long-term administration of aluminum hydroxide led to an increase in AST levels and a decrease in urea levels. The animals exposed to aluminum showed higher lipid and protein oxidation in all the organs analyzed. In relation to the enzymes involved in antioxidant defense, the lungs showed lower superoxide dismutase (SOD) and catalase activity and a lower reduced and oxidized glutathione (GSH/GSSG) ratio. In the liver, aluminum administration led to a decrease in catalase activity and the GSH/GSSG ratio. Lower catalase activity was observed in the small intestine, as well as in the lungs and liver. In addition to alterations in antioxidant defense, increased levels of the chemokine CCL-2 were observed in the lungs, lower levels of IL-10 in the liver and small intestine, and decreased levels of IL-6 in the intestine of the animals that received aluminum hydroxide for 6 months. Long-term exposure to aluminum promoted steatosis in the liver. In the kidneys, mice treated with aluminum presented a decreased glomerular density than in the naive control group. In the small intestine, exposure caused villi shortening. Our results indicate that long-term oral administration of aluminum hydroxide provokes systemic histological damage, inflammation, and redox imbalance.

Acute Aluminum Sulfate Triggers Inflammation and Oxidative Stress, Inducing Tissue Damage in the Kidney of the Chick

In this study, a total of 20 7-day-old chicks were randomly divided into an experimental group and a control group. The experimental group was administered aluminum sulfate (Al₂(SO₄)₃) once by gavage, and the control group was sacrificed after 24 h of fasting with distilled water. Serum and kidney tissue samples from both groups were collected and compared using hematoxylin-eosin staining (H&E) and microscopy. The Paller scores increased (p < 0.01) for biochemical kidney function, redox-related indicators, and mRNA expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) downstream related genes. The results showed that in the kidneys of the experimental group, renal tubular epithelial cells appeared to swell, and there was necrosis and shedding; the blood urea nitrogen (BUN) and uric acid (UA) decreased, serum creatinine (CREA) increased; nitric oxide (NO), glutathione (GSH), and malondialdehyde (MDA) contents increased; NO synthase (NOS), glutathione peroxidase (GSH-PX), and superoxide dismutase (SOD) enzyme activities increased; tumor necrosis factor alpha (TNF-α), tumor necrosis factor receptor 1 (TNF-R1), tumor necrosis factor receptor 2 (TNF -R2), cyclooxygenase-2 (COX-2), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and heme oxygenase-1 (HO-1) mRNA expression levels increased (p < 0.05 or p < 0.01); Nrf2, glutathione S-transferase A3 (GSTA3), glutathione-S-transferase mu-1 (GSTM1), glutathione synthetase (GSS), glutamate cysteine ligase (GCLC and GCLM), quinone oxidoreductase 1 (NQO1), and Kelch-like ECH-associated protein 1 (Keap1) mRNA expression levels decreased (p < 0.05 or p < 0.01) compared to the control group. Acute aluminum poisoning can cause obvious pathological changes in the structure of the kidney tissue of the chick, resulting in damage to the kidney function, as well as triggering inflammation and oxidative stress in the kidney.

Hematologic evaluation of peripheral blood in Sprague Dawley rats by chronic exposure to aluminum chloride (AlCl3)

This study aimed to evaluate whether aluminum chloride (AlCl3) causes hematological changes in the peripheral blood of Sprague-Dawley (SD) rats. Five groups of female SD rats were intragastrically administered with 4 different concentrations of AlCl3 for 5 days a week for a total of 90 days. The aluminum concentration was determined via graphite furnace atomic absorption spectroscopy. Analysis of serum iron-kinetic profiles, blood cytometry outcomes, and blood smears of the blood samples. Scanning electron microscopy (SEM) and Raman spectroscopy were used to search for structural and ultrastructural changes, respectively. Blood aluminum concentration ranged 12.38-16.24 μg/L with no significant difference between experimental treatments. At the AlCl3 concentration of 40 mg Al/kg bw of rats/day, the mean ferritin value in the serum iron kinetic profile was 29.81±6.1 ng/mL, and this value showed a significant difference between experimental treatments. Blood cytometry revealed that there were 6.45-7.11×106 cells/μL erythrocytes, 8.91-9.32×103 cells/μL leukocytes, and 477.2-736.3×103 cells/μL platelets along with a hemoglobin of 37.38-41.93 g/dL and hematocrit level of 37.38-41.93%; the experimental treatments showed no significant differences. Erythrocyte structural analysis using SEM showed no differences between experimental treatments, whereas ultrastructural evaluation using Raman spectroscopy made it possible to identify the following bands: 741, 1123, 1350, 1578, and 1618 cm-1, which were respectively associated with the following vibrational modes and compounds: vibration of the tryptophan ring, asymmetric C-O-C stretching of glucose, C-H curve of tryptophan, C=C stretching of the heme group, and C-N stretching of the heme group, with no significant differences between experimental treatments. Therefore, AlCl3 administration does not induce ultrastructural changes in the erythrocyte membrane. This study revealed that serum ferritin concentration was the only parameter affected by AlCl3 exposure at 40 mg of Al/kg bw of rats/day.

Impact of environmental mercury exposure on the blood cells oxidative status of fishermen living around Mundaú lagoon in Maceió - Alagoas (AL), Brazil

Mercury in the aquatic environment can lead to exposure of the human population and is a known toxic metal due to its capacity for accumulation in organs. We aimed to evaluate the mercury level in the blood and urine of fishermen and correlate it with the level of oxidative stress in blood cells. We show in this case-control study that the fishermen of the exposed group (case) of Mundaú Lagoon (Maceió - Alagoas, Brazil) have higher concentrations of total mercury in the blood (0.73-48.38 μg L^-1) and urine (0.430-10.2 μg L^-1) than the total mercury concentrations in blood (0.29-17.30 μg L^-1) and urine (0.210-2.65 μg L^-1) of the control group. In the blood cells of fishermen, we observed that the lymphomononuclear cells produced high levels of reactive oxygen species (61.7%), and the erythrocytes presented increased lipid peroxidation (151%) and protein oxidation (41.0%) and a decrease in total thiol (36.5%), GSH and the REDOX state (16.5%). The activity of antioxidant system enzymes (SOD, GPx, and GST) was also reduced in the exposed group by 26.9%, 28.3%, and 19.0%, respectively. Furthermore, hemoglobin oxygen uptake was decreased in the exposed group (40.0%), and the membrane of cells presented increased osmotic fragility (154%) compared to those in the control group. These results suggest that mercury in the blood of fishermen can be responsible for causing impairments in the oxidative status of blood cells and is probably the cause of the reduction in oxygen uptake capacity and damage to the membranes of erythrocytes.

Comparative Study on the Protective Effect of Chlorogenic Acid and 3-(3-Hydroxyphenyl) Propionic Acid against Cadmium-Induced Erythrocyte Cytotoxicity: In Vitro and In Vivo Evaluation

The metabolism of chlorogenic acid (CGA) through the intestinal tract was studied. As cadmium is a well-known toxic heavy metal, this study was carried out to investigate the comparative protective effect of CGA and its representative intestinal metabolite (3-(3-hydroxyphenyl) propionic acid, HPPA) against Cd-induced erythrocyte cytotoxicity in vitro and in vivo. We found that CGA and its intestinal metabolite appreciably prevented erythrocyte hemolysis, osmotic fragility, and oxidative stress induced by Cd. Also, we found that HPPA had a stronger protective ability than CGA against Cd-induced erythrocyte injury in vivo, such as increasing the ratio of protein kinase C from 7.7% (CGA) to 12.0% (HPPA). Therefore, we hypothesized that CGA and its microbial metabolite had protective effects against Cd-induced erythrocyte damage via multiple actions including antioxidation and chelation. For humans, CGA supplementation may be favorable for avoiding Cd-induced biotoxicity.

Aluminum hydroxide nebulization-induced redox imbalance and acute lung inflammation in mice

Purpose: Aluminum is the third most abundant metal in the earth's crust and is widely used in industry. Chronic contact with aluminum results in a reduction in the activity of electron transport chain complexes, leading to excessive production of reactive oxygen species (ROS) and oxidative stress. This study aimed to evaluate the effects of short-term exposure of aluminum hydroxide on oxidative stress and pulmonary inflammatory response.Materials and methods: Male BALB/c mice were divided into three groups: control group (CG); phosphate buffered saline group (PBSG) and aluminum hydroxide group (AHG). CG was exposed to ambient air, while PBSG and AHG were exposed to PBS or aluminum hydroxide solutions via nebulization, three times per day for five consecutive days. Twenty-four hours after the last exposure, all animals were euthanized for subsequent analysis.Results: Exposure to aluminum hydroxide in the blood resulted in lower platelet levels, higher neutrophils, and lower monocytes compared to CG and PBSG. Aluminum hydroxide promoted the recruitment of inflammatory cells to the lung. Macrophage, neutrophil and lymphocyte counts were higher in AHG compared to CG and PBSG. Protein oxidation and superoxide dismutase activity were higher, while catalase activity and reduced and oxidizes glutathione ratio in AHG were lower compared to CG and PBSG. Furthermore, there was an increase in the inflammatory markers CCL2 and IFN-γ in AHG compared to CG and PBSG.Conclusion: In conclusion, short-term nebulization with aluminum hydroxide induces the influx of inflammatory cells and oxidative stress in adult BALB/c mice.

Aluminium toxicosis: a review of toxic actions and effects

Aluminium (Al) is frequently accessible to animal and human populations to the extent that intoxications may occur. Intake of Al is by inhalation of aerosols or particles, ingestion of food, water and medicaments, skin contact, vaccination, dialysis and infusions. Toxic actions of Al induce oxidative stress, immunologic alterations, genotoxicity, pro-inflammatory effect, peptide denaturation or transformation, enzymatic dysfunction, metabolic derangement, amyloidogenesis, membrane perturbation, iron dyshomeostasis, apoptosis, necrosis and dysplasia. The pathological conditions associated with Al toxicosis are desquamative interstitial pneumonia, pulmonary alveolar proteinosis, granulomas, granulomatosis and fibrosis, toxic myocarditis, thrombosis and ischemic stroke, granulomatous enteritis, Crohn's disease, inflammatory bowel diseases, anemia, Alzheimer's disease, dementia, sclerosis, autism, macrophagic myofasciitis, osteomalacia, oligospermia and infertility, hepatorenal disease, breast cancer and cyst, pancreatitis, pancreatic necrosis and diabetes mellitus. The review provides a broad overview of Al toxicosis as a background for sustained investigations of the toxicology of Al compounds of public health importance.

Aluminum chloride causes 5-fluorouracil resistance in hepatocellular carcinoma HepG2 cells

Chemoresistance is one of the major obstacles in chemotherapy-based hepatocellular carcinoma (HCC) intervention. Aluminum (Al) is an environmental pollutant that plays a vital role in carcinogenesis, tumorigenesis, and metastasis. However, the effect of Al on chemoresistance remains unknown. 5-Fluorouracil (5-FU) is a widely used antitumor drug. Therefore, we investigated the effects of aluminum chloride (AlCl₃ ) on the chemoresistance of HepG2 cells to 5-FU and explored the underlying mechanisms of these effects. The results demonstrated that AlCl₃ pretreatment attenuated 5-FU-induced apoptosis through Erk activation and reversed 5-FU-induced cell cycle arrest by downregulating p-Chk2^Thr68 levels. In addition, AlCl₃ markedly increased the levels of proteins associated with cell migration, such as MMP-2 and MMP-9. Further investigation demonstrated that an Erk inhibitor (U0126) reversed the AlCl₃ -induced decrease in apoptosis, enhancement of cell cycle progression, promotion of cell migration, and attenuation of oxidative stress. In summary, AlCl₃ induced chemoresistance to 5-FU in HepG2 cells. The present study suggests a potential influence of AlCl₃ on 5-FU therapy. These findings may help others to understand and properly address the resistance of HCC to chemotherapeutic agents.

Chlorogenic acid protects against aluminum toxicity via MAPK/Akt signaling pathway in murine RAW264.7 macrophages

Aluminum (Al), which may bring about damage to the macrophages, has been implicated in the development of immunological diseases. It has been reported that chlorogenic acid (CGA, 5‑caffeoylquinic acid, chemical formula: C₁₆H₁₈O₉) is a natural antioxidant and chelating agent with the capacity against Al (III)-induced biotoxicity. The present study was carried out to investigate whether CGA could reduce AlCl₃-induced cellular damage in RAW264.7 cells. After treatment with AlCl₃, the inhibition rate of viability and phagocytic activity of RAW264.7 cells was 54.5% and 27.6%, respectively. Administration of CGA significantly improved the integrity and phagocytic activity, and attenuated the accumulation of intracellular Al(III) level and oxidative stress in Al(III)-treated cells. Furthermore, CGA significantly inhibited Al(III)-induced increase of phospho-Jun N-terminal kinase (p-JNK), a pro-apoptotic Bcl-2 family protein (Bad), cytochrome c and decrease of extracellular regulated protein kinases (ERK1/2), protein kinase B (Akt) protein expressions. These results showed that CGA has a protective effect against Al(III)-induced cytotoxicity through mitogen-activated protein kinase (MAPK)/Akt-mediated caspase pathways in RAW264.7 cells.