Titanium dioxide nanoparticles: revealing the mechanisms underlying hepatotoxicity and effects in the gut microbiota

Titanium dioxide-induced fibrotic liver model and the therapeutic effect of resveratrol by modulation of α-SMA and 8-oHdG expressions, oxidative stress, and inflammation

The research sought to assess the therapeutic impact of resveratrol by biochemical, immunohistochemical, and histopathological analyses in a TiO2-induced liver fibrosis model. Titanium dioxide (100 mg/kg body weight) was delivered for 15 days to induce liver fibrosis, either alone or in conjunction with resveratrol (30 mg/kg body weight) therapy for the same duration. Resveratrol has been identified as a crucial therapeutic drug that provides an alternative treatment method for TiO2-induced liver fibrosis by mitigating inflammation, oxidative stress, and the expressions of α-SMA and 8-OHdG. Resveratrol treatment mitigated TiO2-induced liver fibrosis by repairing hepatocellular injury and decreasing plasma AST, ALT, and ALP levels. Resveratrol improves the activity of superoxide dismutase (SOD) and catalase (CAT), crucial enzymes for antioxidant defense, and elevates glutathione peroxidase (GSH-Px) levels, so augmenting antioxidant function. Furthermore, resveratrol decreased hepatic inflammation (IL-6 and IL-1β) and oxidative stress markers. Furthermore, histological alterations and immunohistochemistry expression of α-SMA and 8-OhdG were reinstated after resveratrol administration in the TiO2-induced liver fibrosis model. Our research indicates that resveratrol administration effectively protects against liver fibrosis produced by TiO2.

Gastrointestinal dysfunction as the main performance of the oral toxicity of titanium dioxide nanoparticle on gastric ulcer rats

Titanium dioxide nanoparticles (TiO2 NPs) have promising applications in food additives and pharmaceutical dressings, raising concerns about their oral safety. The current studies mainly focus on healthy groups, and the effect of TiO2 NPs on the patient population is rarely known. Here, a comprehensive toxicity study of TiO2 NPs (75 ± 15 nm, anatase) in gastric ulcer rats (male 8-week old Sprague-Dawley rats) is reported following oral exposure at dose of 0, 10, 50, 200 mg/kg body weight per day for 30 days. The gastric ulcer rats were produced by submucosal injection of acetic acid solution into the rat stomach. The healthy rats were used as the normal control. We evaluated nanoparticle biodistribution, systemic toxicity, and gastrointestinal function indices in the rats. Our findings indicate that oral administration of TiO2 NPs resulted in minimal intestinal absorption and transport with limited systemic organ toxicity. The internalization of TiO2 NPs and activation of mast cells in the stomach tissues, along with the low serum levels of histamine and IgE, suggest a localized allergic reaction rather than a systemic one. Furthermore, the notably reduced plasma levels of D-lactate and the activity of diamine oxidase (DAO) indicated the upregulation of intestinal barrier function. These statistically significant results indicated that gastrointestinal dysfunction was the main performance of the oral toxicity of TiO2 NPs on gastric ulcer rats, emphasizing the importance of controlling the intake of TiO2 NPs in patients with gastric ulcers.

Skeletal muscle metabolic dysfunction with circulating carboxymethyl-lysine in dietary food additive-induced leaky gut

Impaired intestinal permeability induces systemic inflammation and metabolic disturbance. The effect of a leaky gut on metabolism in skeletal muscle, a major nutrient consumer, remains unclear. In this study, we aimed to investigate the glucose metabolic function of the whole body and skeletal muscles in a mouse model of diet-induced intestinal barrier dysfunction. At Week 2, we observed higher intestinal permeability in mice fed a titanium dioxide (TiO2)-containing diet than that of mice fed a normal control diet. Subsequently, systemic glucose and insulin tolerance were found to be impaired. In the skeletal muscle, glucose uptake and phosphorylation levels in insulin signaling were lower in the TiO2 group than those in the control group. Additionally, the levels of pro-inflammatory factors were higher in TiO2-fed mice than those in the control group. We observed higher carboxymethyl-lysin (CML) levels in the plasma and intestines of TiO2-fed mice and lower insulin-dependent glucose uptake in CML-treated cultured myotubes than those in the controls. Finally, soluble dietary fiber supplementation improved glucose and insulin intolerance, suppressed plasma CML, and improved intestinal barrier function. These results suggest that an impaired intestinal barrier leads to systemic glucose intolerance, which is associated with glucose metabolism dysfunction in the skeletal muscles due to circulating CML derived from the intestine. This study highlights that the intestinal condition regulates muscle and systemic metabolic health.

Evaluating the adverse effects and mechanisms of nanomaterial exposure on longevity of C. elegans: A literature meta-analysis and bioinformatics analysis of multi-transcriptome data

Exposure to large-size particulate air pollution (PM2.5 or PM10) has been reported to increase risks of aging-related diseases and human death, indicating the potential pro-aging effects of airborne nanomaterials with ultra-fine particle size (which have been widely applied in various fields). However, this hypothesis remains inconclusive. Here, a meta-analysis of 99 published literatures collected from electronic databases (PubMed, EMBASE and Cochrane Library; from inception to June 2023) was performed to confirm the effects of nanomaterial exposure on aging-related indicators and molecular mechanisms in model animal C. elegans. The pooled analysis by Stata software showed that compared with the control, nanomaterial exposure significantly shortened the mean lifespan [standardized mean difference (SMD) = -2.30], reduced the survival rate (SMD = -4.57) and increased the death risk (hazard ratio = 1.36) accompanied by upregulation of ced-3, ced-4 and cep-1, while downregulation of ctl-2, ape-1, aak-2 and pmk-1. Furthermore, multi-transcriptome data associated with nanomaterial exposure were retrieved from Gene Expression Omnibus (GSE32521, GSE41486, GSE24847, GSE59470, GSE70509, GSE14932, GSE93187, GSE114881, and GSE122728) and bioinformatics analyses showed that pseudogene prg-2, mRNAs of abu, car-1, gipc-1, gsp-3, kat-1, pod-2, acdh-8, hsp-60 and egrh-2 were downregulated, while R04A9.7 was upregulated after exposure to at least two types of nanomaterials. Resveratrol (abu, hsp-60, pod-2, egrh-2, acdh-8, gsp-3, car-1, kat-1, gipc-1), naringenin (kat-1, egrh-2), coumestrol (egrh-2) or swainsonine/niacin/ferulic acid (R04A9.7) exerted therapeutic effects by reversing the expression levels of target genes. In conclusion, our study demonstrates the necessity to use phytomedicines that target hub genes to delay aging for populations with nanomaterial exposure.