Metal salts with low oral bioavailability and considerable exposures from ubiquitous background: Inorganic aluminum salts as an example for issues in toxicity testing and data interpretation

Aluminum, a colorful gamechanger: Uptake of an aluminum-containing food color in human cells and its implications for human health

Aluminum is added to many food colors to change their solubility. This study compares the aluminum-containing food color carmine with its aluminum-free version carminic acid (both E 120), hypothesizing that the addition of aluminum does not only change the color's solubility, but also its effects on human cells. We could show that carmine, but not carminic acid, is taken up by gastrointestinal Caco-2 and umbilical vein endothelial cells (HUVEC). Clear differences between gene expression profiles of Caco-2 cells exposed to carmine, carminic acid or control were shown. KEGG analysis revealed that carmine-specific genes suppress oxidative phosphorylation, and showed that this suppression is associated with neurodegenerative diseases such as Alzheimer and Parkinson disease. Furthermore, carmine, but not carminic acid, increased proliferation of Caco-2 cells. Our findings show that a food color containing aluminum induces different cellular effects compared to its aluminum-free form, which is currently not considered in EU legislation.

The evolving role of investigative toxicology in the pharmaceutical industry

For decades, preclinical toxicology was essentially a descriptive discipline in which treatment-related effects were carefully reported and used as a basis to calculate safety margins for drug candidates. In recent years, however, technological advances have increasingly enabled researchers to gain insights into toxicity mechanisms, supporting greater understanding of species relevance and translatability to humans, prediction of safety events, mitigation of side effects and development of safety biomarkers. Consequently, investigative (or mechanistic) toxicology has been gaining momentum and is now a key capability in the pharmaceutical industry. Here, we provide an overview of the current status of the field using case studies and discuss the potential impact of ongoing technological developments, based on a survey of investigative toxicologists from 14 European-based medium-sized to large pharmaceutical companies.

Rapamycin nanoparticles improves drug bioavailability in PLAM treatment by interstitial injection

BACKGROUND

Pulmonary lymphangiomyomatosis (PLAM) is a rare interstitial lung disease characterized by diffuse cystic changes caused by the destructive proliferation of smooth muscle-like cells or LAM cells. PLAM is more common in young women than other people, and a consensus is lacking regarding PLAM treatment. The clinical treatment of PLAM is currently dominated by rapamycin. By inhibiting the mTOR signaling pathway, rapamycin can inhibit and delay PLAM's occurrence and development. However, the application of rapamycin also has shortcomings, including the drug's low oral bioavailability and a high binding rate to hemoglobin, thus significantly decreasing the amount of drug distributed to the lungs.

METHODS AND RESULTS

Here, we developed a new mode of rapamycin administration in which the drug was injected into the intrathecal space after being nanosized; the directional flow characteristics of the liquid in the intrathecal space were exploited to increase the drug content in the interstitial fluid to the greatest extent possible. We studied the rapamycin content in the interstitial fluid and blood after intervaginal space injection (ISI). Compared with oral administration, ISI significantly increased the drug concentration in the lung interstitial fluid.

CONCLUSIONS

These results provided new ideas for treating PLAM and optimizing the dosing regimens of drugs with similar characteristics to rapamycin.

Innovative In Vitro Strategy for Assessing Aluminum Bioavailability in Oral Care Cosmetics

Aluminum is an element found in nature and in cosmetic products. It can interfere with the metabolism of other cations, thus inducing gastrointestinal disorder. In cosmetics, aluminum is used in antiperspirants, lipsticks, and toothpastes. The aim of this work is to investigate aluminum bioavailability after accidental oral ingestion derived from the use of a toothpaste containing a greater amount of aluminum hydroxide than advised by the Scientific Committee on Consumer Safety (SCCS). To simulate in vitro toothpaste accidental ingestion, the INFOGEST model was employed, and the amount of aluminum was measured through the ICP-AES analysis. Tissue barrier integrity was analyzed by measuring transepithelial electric resistance, and the tissue architecture was checked through light microscopy. The margin of safety was also calculated. Overall, our results indicate that the acute exposure to aluminum accidentally ingested from toothpastes is safe for the final user, even in amounts higher than SCCS indications.

Neurotoxic effects of combined exposures to aluminum and mercury in early life (infancy)

Aluminum and mercury are environmentally ubiquitous. Individually they are both neurotoxic elements with shared neuro-pathogenic pathways: oxidative stress, altered neurotransmission, and disruption of the neuroendocrine and immune systems. In the infant, Al and Hg differ in type of exposure, absorption, distribution (brain access), and metabolism. In environmentally associated exposure (breast milk and infant formulas) their co-occurrences fluctuate randomly, but in Thimerosal-containing vaccines (TCVs) they occur combined in a proprietary ratio; in these cases, low-doses of Thimerosal-ethylmercury (EtHg) and adjuvant-Al present the most widespread binary mixture in less developed countries. Although experimental studies at low doses of the binary Hg and Al mixture are rare, when studied individually they have been shown to affect neurological outcomes negatively. In invitro systems, comparative neurotoxicity between Al and Hg varies in relation to the measured parameters but seems less for Al than for Hg. While neurotoxicity of environmental Hg (mainly fish methyl-Hg, MeHg) is associated with neurobehavioral outcomes in children, environmental Al is not associated, except in certain clinical conditions. Therefore, the issues of their neurotoxic effects (singly or combined) are discussed. In the infant (up to six months) the organic-Hg and Al body burdens from a full TCV schedule are estimated to reach levels higher than that originating from breastfeeding or from high aluminum soy-based formulas. Despite worldwide exposure to both Al and Hg (inorganic Hg, MeHg, and Thimerosal/EtHg), our knowledge on this combined exposure is insufficient to predict their combined neurotoxic effects (and with other co-occurring neurotoxicants).