Hydroxyurea (HU) is an inhibitor of ribonucleotide reductase, which is commonly used to treat bone marrow proliferative diseases and sickle cell anemia. In addition, HUD is used as an antineoplastic drug to treat various malignant tumors, such as melanoma; leukemia; oophoroma; Head and neck cancer. In addition, it is often used to treat HIV infection and sickle cell disease, polycythemia vera and primary thrombocytopenia. Although it has beneficial effects, there are many reports about its gonadal toxicity, cytotoxicity and genotoxic effects. The comprehensive mechanism of HDU induced gonadal toxicity (decreased sperm production and spermatogenesis arrest, decreased oocyte maturation) and cytotoxicity can be explained by the excessive production of reactive oxygen species. HDU can also induce apoptosis in fetal tissues and cancer cell lines. In addition, some reports described the hepatotoxic effects of HDU, including hepatitis, liver dysfunction and acute elevation of liver function indicators; However, the mechanism of this effect has not been thoroughly studied.
Royal jelly (RJ) is a thick milky white substance secreted by young emerging worker bees. Its ingredients include 60-70% water, 9-18% protein and 10-16% total sugar, as well as a small amount of free amino acids, vitamins, salts and lipids. Some valuable properties of RJ have been reported, including anti-inflammatory, anti-tumor, antihypertensive and accelerating immune response. In addition, many studies have proved that RJ has antioxidant and liver protective effects.
The purpose of this study was to explore the hepatotoxic effect of HDU from the perspective of liver oxidation / antioxidant status, proinflammatory cytokines, apoptosis signaling pathway and histopathology. In addition, the protective effect of RJ on HDU induced liver injury was also studied.
- Survival rate and weight change
During the experiment, the number of animal deaths was recorded every week, and the survival rate of the control group was 88.8%; The survival rate of each group was as follows: rj:88.8%; HDU： 80. %； 2HDU： 72.72%; RJ+HDU： 66.6%; Rj+2hdu:66.6% (Figure 1). As shown in figures 2 (a) and 2 (b), compared with the control group, the weight and liver body index of rats in HDU group and 2hdu group decreased significantly (P <0.001). In addition, the body weight and liver body index of rj+ HDU group and rj+2hdu group were significantly higher than those of HDU group and 2hdu group.
- Serum hepatocyte enzymes
As shown in Figure 3, the levels of serum hepatocyte enzymes (AST, ALT and ALP) in HDU group and 2hdu group were significantly increased (P <0.001), both higher than those in the control group. In addition, compared with the control group, the serum liver cell enzyme content of rats treated with therapeutic dose of HDU almost doubled. At the same time, twice the dose of HDU showed a fourfold increase in serum hepatocyte enzymes. Interestingly, the serum hepatocyte enzyme level of RJ + HDU group decreased significantly (p<0.001) to the level of control group, and that of RJ + 2hdu group decreased by about 40%.
- Liver oxidative stress
The effects of HDU and RJ on oxidative stress in the liver of rats in the control group and the treatment group are shown in Figure 4. Compared with the control group, liver MDA and no increased, which was more obvious in high-dose HDU (p<0.001). After RJ + HDU treatment, MDA content decreased significantly (P <0.001) to the level of the control group, but no decreased significantly by about 26% (P <0.001). In addition, after RJ treatment, rats receiving double dose HDU significantly reduced the harmless effects of HDU on liver MDA and no by 39.3% and 26.3%, respectively (P <0.001).
- Liver antioxidant status
As shown in Figure 5 Compared with the control group, HDU caused a significant decrease in liver GSH, SOD and GPX (p<0.001), especially at high doses of HDU. Similarly, the therapeutic dose of HDU administered by RJ significantly reduced the harmful effects of HDU on liver tissue by increasing GSH levels and increasing SOD and GPX contents by about 23.5% and 35%, but still did not reach the level of the control group (Fig. 3). Compared with 2hdu group, RJ rats receiving double dose of HDU showed significant difference (p<0.001), which reduced the contents of GSH, SOD and GPX by 139.3%, 73% and 100% respectively compared with the control level.
- Apoptosis biomarker (caspase-3)
As shown in Figure 6, caspase-3 protein expression in control group and RJ rats was negative (no expression). Caspase-3 protein in hepatocytes of HDU poisoned rats showed weak to moderate or positive immune response. In addition, 2hdu poisoned rats showed moderate to strong brown caspase-3 expression. Oral RJ showed weak expression of Caspase-3 in HDU, and weak to moderate immunostaining of Caspase-3 in 2hdu poisoned rats. The immunostaining of Caspase-3 in the liver tissue of rats treated with HDU and 2hdu was 12 ± 0.28% and 22.4 ± 0.16%, respectively. When RJ was administered, the caspase-3 immunostaining caused by HDU was significantly reduced (P <0.001).
- Proinflammatory cytokines (TNF- α）
Proinflammatory cytokines (TNF- α) The expression in different groups is shown in Figure 7. TNF in control group and RJ rats- α Negative expression. The immune reaction of hepatocytes in rats poisoned by HDU was weak to moderate positive. 2hdu poisoned rats showed moderate to strong brown expression. TNF in HDU after oral administration of RJ- α The expression is weak, and the immunostaining of 2hdu poisoned rats is weak to moderately positive. TNF in rat liver treated with HDU and 2hdu- α The immunostaining area% were 8.7 ± 0.79% and 14.4 ± 0.38% respectively. Similarly, TNF- α Immunostaining was significantly reduced at RJ Administration (P <0.001), and single and double dose HDU decreased by 55.8% and 56.6% respectively.
- Liver histopathology
As shown in Figure 8. Compared with the control group, rats treated with therapeutic dose of HDU showed mild to moderate liver damage. The recorded lesions were hyperemia, moderate to severe watery degeneration of hepatocytes, multifocal liver necrosis, inflammatory cell infiltration with biliary cell degeneration. Meanwhile, compared with the control group, rats in the double dose HDU treatment group had moderate to severe liver damage. Liver lesions are diffuse, mild to severe cellular vacuolation, water denaturation and steatosis. At the same time, rats treated with 2hdu showed multifocal coagulative hepatocyte necrosis, accompanied by inflammatory cell infiltration and multifocal hepatocyte apoptosis. Oral administration of royal jelly shortly after HDU and 2hdu can reduce the liver damage caused by HDU.
The current data provide additional information about the hepatotoxicity of the antineoplastic drug hydroxyurea, especially in the case of high doses of hydroxyurea. In addition, royal jelly may play a protective role against HDU induced liver injury through its antioxidant, anti-inflammatory and anti apoptotic properties. Therefore, royal jelly can be used as an adjuvant treatment to prevent liver injury caused by hydroxyurea.
Source of original text: Tohamy HG， El-Neweshy MS， Soliman MM， et al. Protective potential of royal jelly against hydroxyurea -induced hepatic injury in rats via antioxidant， anti-inflammatory， and anti-apoptosis properties. PLoS One. 2022;17(3)：e0265261. Published 2022 Mar 18. doi：10.1371/journal.pone.0265261