Publish Time: 2022-10-31 Origin: Site
Hyaluronic acid has excellent water retention in biological tissues and is widely used in skin care products.
Ultraviolet (UV) rays can cause various types of skin damage when exposed to sunlight.
In this paper, the repairing effects of HA on various skin damage caused by UV were reviewed from the aspects of scavenging free radicals, anti-inflammatory, anti-lipid oxidation, and anti-apoptosis. As the research on the performance of HA in after-sun repair continues to deepen, it will have higher application value and better development prospects in skin care products.
In recent years, due to the increasing ultraviolet radiation, the incidence of various skin diseases such as sunburn, tanning, polymorphic photorash and even skin cancer has gradually increased due to UV-induced skin photodamage.
UV in sunlight can be divided into 3 bands: short-wave ultraviolet (UVC), medium-wave ultraviolet (UVB) and long-wave ultraviolet (UVA), with wavelengths of 200~280, 280~320 and 320~400nm, respectively. Among them, ultraviolet rays with wavelengths of 290-400 nm can cause skin damage, and the number of skin erythema caused by UV increases in a dose-dependent manner. UV irradiation can induce the production of reactive oxygen species (ROS) and promote the production of cellular inflammatory factors, such as nuclear factor (NF-κB), tumor necrosis factor (TNF-α), interleukin factor (IL), etc.
Hyaluronic acid (HA) is a non-race-specific acid mucopolysaccharide commonly found in the intercellular matrix of biological skin and musculoskeletal tissues. It has excellent water retention and good transdermal absorption properties. In the body, there are many important physiological functions such as lubricating joints, regulating the permeability of blood vessel walls, and promoting wound healing.
UV irradiation can cause skin keratinocytes to generate ROS, which are mainly divided into superoxide anion radicals (O2•-) and hydroxyl radicals (•OH). Excessive ROS can destroy components in skin keratinocytes, such as liposomes, proteins and DNA. Hiramoto et al. found that exposure of mice to UVB radiation can lead to increased ROS levels in mice and induce inflammation.
Superoxide anion free radicals are free radical precursors that can react with biological macromolecules and cause tissue damage, and play an important role in the formation of ROS. The results of the study on the ability of HA to scavenge superoxide anion radicals showed that the scavenging activity of low molecular weight hyaluronic acid (LMWHA) on superoxide anion radicals was positively correlated with its concentration and had a dose-dependent relationship. The clearance rate was 87.12%.
Hydroxyl free radicals and their derivatives are highly destructive ROS that can significantly destroy biological macromolecules in skin keratinocytes. When the mass concentration of HA was between 1 and 5 mg/ml, its ability to scavenge hydroxyl radicals showed a dose-dependent relationship. The study found that in the concentration range of 69~1110μg/ml, the activity of LMWHA in scavenging hydroxyl radicals was significantly higher than that of HA; when the concentration was 1110μg/ml, the scavenging rates of LMWHA and HA to hydroxyl radicals were 91.711% and 79.536%, respectively.
The lipids on the skin's keratinocyte membrane can maintain the normal structure of cells and regulate cell function, while the lack of lipids between keratinocytes can lead to skin barrier damage. UV irradiation can interfere with the signaling process of keratinocytes to a certain extent, resulting in the production of ROS, which attack and induce peroxidation of the cell membrane of keratinocytes and their lipids.
Lipid peroxidation end products such as lipid peroxidation can directly or indirectly damage DNA molecules in cells. Studies by Sivaranjani et al have shown that the level of malondialdehyde in venous blood of patients with atopic dermatitis is higher than that of healthy control subjects, and lipid peroxidation is the main factor in the pathogenesis of atopic dermatitis.
Keratinocytes in the epidermis are exposed to UV radiation, which will induce excessive production of NF-κB and interleukin factors (interleukin-1β, interleukin-6, interleukin-8, IL-1β, IL-6, IL-8), etc. Inflammatory cytokines induce skin inflammation from multiple links at the molecular level. Studies have found that HA can inhibit the expression of inflammatory cytokines produced by UV radiation.
ROS generated by human keratinocytes (HaCaT) after long-term exposure to UV radiation can regulate apoptosis-related genes to damage keratinocyte DNA; damage the activity of antioxidant enzymes in cells; damage biofilms and lead to keratinocyte apoptosis.
When the UVB irradiation dose is 30mJ/cm⊃2; and long-term irradiation, various biological metabolic functions in HaCaT cells can be damaged, resulting in cell apoptosis and necrosis. At present, some research progress has been made in the inhibitory effect of HA on skin cell apoptosis induced by UV irradiation.
HA was added to the chitosan and gelatin system to evaluate the apoptosis of L929 human fibroblasts. The results showed that the chitosan-gelatin mixture containing HMWHA could inhibit apoptosis through the cell membrane, which could be inhibited by CD44 complex on cells. Body-inducible reactive sites interact with cell adhesion factors to reduce the percentage of apoptosis.
Therefore, HA has a good effect on resisting the apoptosis of skin cells induced by UV irradiation.
UV exposure is an important factor in the pathogenesis of rosacea. Si Hongli et al. studied rosacea and UV minimum erythema, and all rosacea patients in the study sample aggravated the disease under sun exposure.
A study of HA dressing combined with CO⊃2; fractional laser in the treatment of acne pitted scars shows that HA can significantly improve the symptoms of acne pitted scars by promoting the expression of collagen, thereby accelerating wound repair.
UV irradiation can lead to increased skin transepidermal water loss (TEWL) and changes in stratum corneum lipid content and damage the skin barrier function. And the minimum erythema dose UVB irradiation can significantly inhibit the metabolism of natural moisturizing factors in keratinocytes, reduce the water content of the stratum corneum, and thus damage the skin barrier function.
At present, the TEWL value is an indicator for judging the function of the skin barrier. When the TEWL value increases, the skin is prone to dryness, scaling, and sensitivity, resulting in damage to the skin barrier. Li Jianghui studied the effect of HA repairing biofilm on the skin barrier function of children with atopic dermatitis. The results showed that after treatment, the sebum content and stratum corneum water content of the observation group were significantly lower than those of the control group, and the TEWL values of the two groups of children were significantly lower. before treatment. Ma Ying et al. studied the changes in TEWL value of HA spray applied to the skin of patients after facial laser surgery. The TEWL value of the control group and the observation group decreased significantly after 14 days after using the HA spray compared with the first day after the operation.
In conclusion, HA can significantly improve the water content of the skin stratum corneum, and the TEWL value is significantly reduced, indicating that HA can effectively improve the skin barrier function.
UV irradiation will increase the content of matrix metalloproteinase (MMP) in epidermal keratinocytes, which will lead to the breakdown of collagen and elastin, and trigger skin aging.
Studies have shown that HA has a certain improvement effect on the increase of MMPs content induced by UV irradiation. Li Yiwen studied HA to improve the symptoms of skin photoaging in rats after UV irradiation. The rats were divided into blank control group, UV irradiation model group and HA group. At the 10th week, UV irradiation was stopped, and HA was smeared on the test site of the back of the rats in the HA group before each irradiation. The results showed that the skin elasticity in the HA group was significantly higher than that in the UV irradiation group, and the MMP-1 in the HA group was also significantly lower than that in the UV irradiation group.
With the rapid development of the cosmetics industry and the improvement of consumers' awareness of skin health, HA is an important functional raw material in cosmetics, and its various functional activities have been continuously developed and applied. Among them, sodium hyaluronate can significantly improve some skin problems caused by UV irradiation, such as skin inflammation, lipid peroxidation and apoptosis.
However, hyaluronic acid can also induce inflammation to a certain extent, and the research on this aspect is not deep enough, so the mechanism of side effects of HA under specific conditions of use is still worth exploring. In addition, the mechanism by which HA scavenges ROS to achieve antioxidant effect through self-degradation is not yet clear, and the specific mechanism in this regard deserves attention. The in-depth exploration of these mechanisms will provide more theoretical basis and research directions for the development of HA skin repair related products in the future.