Sexual Dimorphism of Doxorubicin‐Induced Acute Systemic Inflammation
Authors: Grant Marianne K O , Seelig Davis , Sharkey Leslie , Zordoky Beshay N 
Published: November 2023

Background

There is inconclusive evidence about the role of sex as a risk factor of doxorubicin (DOX)‐induced toxicity. Recent experimental studies have shown that adult female rodents are protected against DOX‐induced cardiotoxicity and nephrotoxicity. However, the mechanisms of this sexual dimorphism are not fully elucidated. Increasing clinical and experimental evidence suggests that inflammation contributes significantly to DOX‐induced multi‐organ toxicity. Nevertheless, the sex‐dependent effect of DOX on the expression of key inflammatory markers is still not known. Therefore, in the present study, we determined the effect of acute DOX exposure on the tissue expression and serum level of the key inflammatory markers cyclooxygenase‐2 (Cox‐2), interleukin‐6 (IL‐6), and tumor necrosis factor‐alpha (TNF‐alpha) in male and female C57Bl/6 mice.

Methods

Acute DOX toxicity was induced by a single intra‐peritoneal injection of 20 mg/kg DOX in male and female adult C57Bl/6 mice. Mice were euthanized one day after DOX or saline injection. Hearts, kidneys, and livers were harvested, weighed, and snap frozen in liquid nitrogen. Blood was collected and serum was separated. Total RNA was extracted from the frozen tissues, and gene expression of inflammatory markers was measured by real‐time PCR. The serum levels of inflammatory markers were measured using Luminex magnetic bead technology. Another cohort of mice was euthanized 6 days after DOX or saline injection to evaluate heart and kidney sections for pathological lesions.

Results

Acute DOX exposure altered the gene expression of several inflammatory markers in a sex‐dependent and organ‐specific manner. In the heart, acute DOX exposure induced Cox‐2 and inhibited TNF‐alpha gene expression in male, but not female, mice. In contrast, both Cox‐2 and TNF‐alpha were induced in the kidney of female, but not male, mice. The gene expression of IL‐6 was not quantifiable in the heart or kidney of either sex. In the liver, DOX induced gene expression of all measured inflammatory markers, in male, but not female, mice. In serum, the increase of IL‐6 was much greater in DOX‐treated males than in DOX‐treated females. TNF‐alpha was increased to the same level in both male and females. Six‐days after DOX injection, pathological lesions were more severe in the heart and kidney of male DOX‐treated mice than in females.

Conclusions

Acute DOX exposure elicits a marked systemic inflammatory reaction that is sex‐dependent and organ‐specific. Alterations in gene expression and serum levels of inflammatory markers, as well as organ pathology, are more severe in male than in female mice. Since inflammation plays a key role in DOX‐induced multi‐organ toxicity, male‐predominant inflammation may play a role in the sexual dimorphism of DOX‐induced toxicity.

Support or Funding Information

Research was supported by a Pre‐K Career Development Award from the National Center for Advancing Translational Sciences of the National Institutes of Health Award Number UL1TR000114.