Cell toxicity

Anti-Pollution Matrix > Damage > Molecular > Cell toxicity

Explanation

In general, cell toxicity or cytotoxicity manifests itself in the fact that the tissue and the cells are damaged in such a way that they can no longer or only insufficiently perform their original function. Cell toxicity is manifested, for example, in an altered morphology of the cells or tissue, reduced or absent cell division, and even cell lysis. Consequently, the cells and tissue become senescent and die (apoptosis, necrosis). Various forms of pollution (dirt particles, gases or sun exposure) can induce cell toxicity, leading to e.g. skin aging and skin lesions [1-3].

 

Effects on the skin

When pollution, as well as excessive sun exposure, causes apoptosis in skin tissue, the dead cells are increasingly shed, a process called increased desquamation. This serves to get rid of the dead tissue so that it can renew itself. In apoptosis, the cells detach from neighboring cells and become smaller with a condensed nucleus. This also leads to a weakening of the skin barrier, allowing pollution (e.g.: dirt particles) to better penetrate into the skin. A change in the skin microbiome can also be expected.

In senescence, the cells in the tissue are no longer proliferative, but show, for example, the so-called senescence-associated secretory phenotype. In this state, the cells secrete, for example, pro-inflammatory cytokines, which can lead to inflammation, radical formation, degradation of tissue structure, premature skin aging, etc.

 

Measures

Protection from excessive sunlight can be provided, for example, by UV filters in sunscreens or by wearing long clothes. In the case of dirt particles, barrier-strengthening agents are recommended, as are moisturizing creams. Pollution can be washed off the skin with the help of skin cleansers. If necessary, exfoliants can also be used to help the skin slough off dead cells.

Since cell toxicity and cell death are often caused by oxidative stress (free radicals), thus it is also beneficial to support the skin's own antioxidant protection system, for example with vitamins such as vitamin C (ascorbic acid) or vitamin E (tocopherol), which are often found in cosmetic products.

 

Impact detection methods

Cell toxicity is relatively easy to detect in vitro / ex vivo using the following methods:

• MTT assay: unconversion of the water-soluble and yellow 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) into purple formazan. This occurs in cells mainly in energy metabolism and cellular respiration. The formazan can be measured photometrically [4, 5].
• LDH assay: cell lysis, which can occur during cell death, releases the enzyme lactate dehydrogenase (LDH). The activity of LDH can be detected by colorimetric or fluorescent methods.
• Proliferation measurement: Cell proliferation can be measured by BrdU assay. This involves measuring the incorporation of a bromodeoxyuridine (BrdU) into DNA during mitosis. The BrdU is detected with an antibody and measured colorimetrically.
• Oxygen consumption and pH measurement are two other methods that can be used to measure cell toxicity in vitro.
• Histology: Histologically, cell toxicity can be detected, for example, by morphological cell changes such as loose tissue, reduced cell-cell contact or microcell nuclei. Apoptosis is measured fluorometrically by TUNEL staining.
• ELISA assays: detection of cytokines in e.g. fluids from skin biopsies/suction blisters that induce cell death.

Macroscopically (in vivo), increased skin desquamation, evident from rough, white areas on the skin, is a sign of increased cell death.

 

References

[1] E. Araviiskaia et al. The impact of airborne pollution on skin, JEADV (2019) 10.1111/jdv.15583, https://doi.org/10.1111/jdv.15583
[2] K. E. Kim et al. Air pollution and skin diseases: Adverse effects of airborne particulate matter on various skin diseases, Life Scie 152 (2016) 126-134, DOI: 10.1016/j.lfs.2016.03.039
[3] S. Ke et al. Cytotoxicity analysis of indoor air pollution from biomass combustion in human keratinocytes on a multilayered dynamic cell culture platform, Chemosphere 208 (2018) 1008-1017, DOI: 10.1016/j.chemosphere.2018.06.058
[4] M. Gareis, Diagnostischer Zellkulturtest (MTT-Test) für den Nachweis von zytotoxischen Kontaminanten und Rückständen, J. Verbr. Lebensm. 1(2006) 354-363, https://doi.org/10.1007/s00003-006-0058-6
[5] T. Mosmann, Rapid Colorimetric Assay for Cellular Growth and Survival: Application to Proliferation and Cytotoxicity Assays, Journal of lmmunological Methods, 65 (1983) 55-63, https://doi.org/10.1016/0022-1759(83)90303-4