Amelioration of silymarin against cadmium-induced toxicity in pregnant rats and their fetuses

Cadmium toxicity on endoplasmic reticulum functioning

Cadmium (Cd) is a heavy metal pollutant widely distributed in the environment due to industrial activities, mining, and agricultural practices. Cadmium-induced Toxicity exerts profound effects on ER functioning through multiple mechanisms, leading to cellular dysfunction and pathological consequences. Cadmium disrupts protein folding and activates the unfolded protein response (UPR). Cd exposure leads to the accumulation of misfolded proteins, triggering UPR pathways mediated by critical ER transmembrane sensors: IRE1, PERK, and ATF6. The subsequent UPR aims to restore ER homeostasis but can also induce apoptosis under severe stress conditions. Cd disrupts ER calcium homeostasis by inhibiting the SERCA pump, further exacerbating ER stress. The generation of reactive oxygen species (ROS also plays a critical role in Cd toxicity, damaging ER-resident proteins and amplifying UPR activation). Cadmium also affects the lipid metabolism. This review examines the mechanisms by which Cd toxicity impairs ER functioning, disruption of protein folding and quality control mechanisms, and dysregulation of calcium signaling and lipid metabolism. The subsequent cellular consequences, including oxidative stress, apoptosis, and inflammation, are discussed in the context of Cd-induced pathogenesis of diseases such as Cancer and neurodegenerative and cardiovascular disorders. Finally, potential therapeutic strategies must be explored to mitigate the adverse effects of Cd on ER functioning and human health.

Silymarin and MSC-exosomes ameliorate thioacetamide-evoked renal fibrosis by inhibiting TGF-β/SMAD pathway in rats

BACKGROUND

TGF-β1 and SMAD3 are particularly pathogenic in the progression of renal fibrosis.

AIM

This study aimed to evaluate the kidney protective potentials of silymarin (SM) and exosomes of mesenchymal stem cells against the nephrotoxin thioacetamide (TAA) in rats.

METHODS

32 female rats were randomly assigned into four groups: the control group, the TAA group, the TAA + SM group, and the TAA + Exosomes group. The kidney homogenates from all groups were examined for expression levels of TGF-β receptors I and II using real-time PCR, expression levels of collagen type I and CTGF proteins using ELISA, and the expression levels of nuclear SMAD2/3/4, cytoplasmic SMAD2/3, and cytoplasmic SMAD4 proteins using the western blot technique.

RESULTS

Compared to the control group, the injection of TAA resulted in a significant increase in serum levels of urea and creatinine, gene expression levels of TβRI and TβRII, protein expression levels of both collagen I and CTGF proteins, cytoplasmic SMAD2/3 complex, and nuclear SMAD2/3/4 (p-value < 0.0001), with significantly decreased levels of the co-SMAD partner, SMAD4 (p-value < 0.0001). Those effects were reversed considerably in both treatment groups, with the superiority of the exosomal treatment regarding the SMAD proteins and the expression levels of the TβRI gene, collagen I, and CTGF proteins returning to near-control values (p-value > 0.05).

CONCLUSION

Using in vitro and in vivo experimental approaches, the research discovered a reno-protective role of silymarin and exosomes of BM-MSCs after thioacetamide-induced renal fibrosis in rats, with the advantage of exosomes.

The deleterious effects of cadmium on oxidative stress markers, drug-metabolizing, and antioxidant enzyme activities: Role of Silymarin and Garlic as Antioxidants

Exposure to cadmium has been related to liver and kidney diseases such as polycystic and nephrotic syndrome. It is still unclear how cadmium contributes to these diseases. It is believed that the induction of oxidative stress resulting from the inhibition of antioxidant enzyme activities and changes in drug-metabolizing enzymes in the liver could explain the role of cadmium in the development of different diseases in the kidney and probably other organs. Changes in oxidative stress markers, antioxidant enzymes, and drug-metabolizing enzyme activities were assessed in the liver of male rats exposed to cadmium chloride. Additionally, the protective effects of silymarin and garlic extract against cadmium toxicosis were evaluated. Rats were randomly divided into eight groups as follows, groups 1, 2, 3, 4, and 5, received orally saline, CdCl2 (1 mg/kg), garlic extract [800 mg/kg], silymarin (25 mg/kg) and silymarin plus garlic extract respectively for 28 consecutive days. Rats in groups 6, 7, and 8 were pretreated with the same doses of garlic, silymarin, and garlic plus silymarin, respectively for two hours before cadmium administration. The Western immunoblotting technique was used to investigate the protein expression of cytochrome P450 isozymes. Spectrophotometric methods were used to assess the activity of both antioxidant- and drug-metabolizing enzymes. Free radical levels [measured as thiobarbituric acid reactive substances (TBARS)], catalase, superoxide dismutase, and glutathione peroxidase activities increased whereas the levels of glutathione and the activities of glutathione S-transferase, glutathione reductase, and glutamyl transferase, cytochrome P450, aryl hydrocarbon dehydrogenase (AHH), dimethylnitrosamine-N-demethylase I (DMN-dI), 7-ethoxycoumarine-O-deethylase (ECOD), cytochrome b5 and NADPH-Cytochrome-c-reductase enzyme activities decreased after cadmium treatment. Furthermore, Western immunoblotting data revealed that glutathione peroxidase protein expression increased following cadmium exposure, but cytochrome P450 2E1 and 3A4 expressions were downregulated. However, pretreatment of rats with silymarin or garlic extract or both before cadmium administration was found to restore the protein expression of cytochrome P450 2E1 and 3A4, the level of free radicals, antioxidant enzymes, drug-metabolizing enzyme activities to their normal levels. Similarly, histological studies revealed that silymarin and/or garlic extract reduced the liver damage caused by cadmium. Silymarin and/or garlic extract reduced the adverse effects of cadmium on the activity of both drug-metabolizing and antioxidant enzymes activity. These antioxidants could be provided to those who work in cadmium-based sectors to help them cope with the adverse effects of cadmium on their kidneys. In addition, Inhibiting drug-metabolizing enzyme activity should be considered when administering therapeutic medications to persons exposed to cadmium because most therapeutic drugs and many endogenous substances are largely metabolized by these enzymes.