CYP19A1 mediated sex hormone metabolism promotes severe SARS-CoV-2 disease outcome in males.

Male sex belongs to one of the major risk factors for severe COVID-19 outcome. However, underlying mechanisms that could affect sex dependent disease outcome are yet unknown. Here, we identified the CYP19A1 gene encoding for the testosterone-to-estradiol metabolizing enzyme CYP19A1 (alias aromatase) as a male abundant host factor that contributes to worsened disease outcome in SARS-CoV-2 infected male hamsters. Pulmonary CYP19A1 transcription is further elevated upon viral infection in males correlating with reduced testosterone and increased estradiol levels. Dysregulated circulating sex hormone levels in male golden hamsters are associated with reduced lung function compared to females. Treatment of SARS-CoV-2 infected hamsters with letrozole, a clinically approved CYP19A1 inhibitor, supported recovery of dysregulated plasma sex hormone levels and was associated with improved lung function and health in male but not female animals compared to placebo controls. Whole human exome sequencing data analysis using a Machine Learning approach revealed a CYP19A1 activity increasing mutation being associated with the development of severe COVID-19 for men. In human autopsy-derived lungs CYP19A1 was expressed to higher levels in men who died of COVID-19, at a time point when most viral RNA was cleared. Our findings highlight the role of the lung as a yet unrecognized but critical organ regulating metabolic responses upon respiratory virus infection. Furthermore, inhibition of CYP19A1 by the clinically approved drug letrozole may pose a new therapeutic strategy to reduce poor long-term COVID-19 outcome.

SARS-CoV-2 induced CYP19A1 expression in the lung correlates with increased aromatization of testosterone-to-estradiol in male golden hamsters

SARS-CoV-2 infection is associated with increased morbidities in men compared to women. Androgens are believed to play an important role in SARS-CoV-2 pathogenesis in men due to the postulated androgen-dependency of ACE2 and TMPRSS2. However, it is yet unclear whether the sex bias is mediated by SARS-CoV-2 infection itself or by other confounding factors. Here, using the golden hamster model, we show that SARS-CoV-2 infection attacks reproductive organs, causes massive dysregulation of sex hormones and induces elevated transcription of the androgen-to-estrogen converting enzyme aromatase CYP19A1 in the lung. In male hamsters, SARS-CoV-2 infection causes severely depleted testosterone and highly elevated estradiol levels. In female hamsters, SARS-CoV-2 infection causes reduced estradiol levels. Hormonal dysregulation in infected animals is followed by severe weight loss compared to control groups treated with poly(I:C) or PBS. Lungs of SARS-CoV-2 infected animals present abundant CYP19A1 expression in the endothelium and in macrophages, particularly in males. Prominent CYP19A1 expression in endothelial cells and macrophages was verified in lung sections of deceased Covid-19 males compared to females. Our results demonstrate that SARS-CoV-2 infection leads to massive dysregulation of sex hormones, which may increase the risk for sex-specific disease outcome particularly in combination with comorbidities. These findings provide insights into the complex metabolic cross talk between SARS-CoV-2 infection and sex hormones.

Effect of Topical 2% Eucalyptus Extract on 5-FU-Induced Oral Mucositis in Male Golden Hamsters

Oral mucositis is a common inflammatory complication among patients with cancer. This study evaluated the histopathological, stereological, and antioxidant markers of 2% eucalyptus extract in induced oral mucositis in male golden hamsters. In this animal study, oral mucositis was induced in 30 male golden hamsters by 5-FU (60 mg/kg) on days 0, 5, and 10 of the study. The cheek pouch was scratched with a sterile needle once daily on days 3 and 4. On days 14-17, 2% eucalyptus hydroalcoholic extract gel and Calendula officinalis extract gel groups were treated and then compared with a non-treated control group. The histopathological and stereological scores and the pouch content of malondialdehyde, as well as the activities of glutathione and myeloperoxidase in the pouch tissue, were evaluated. Histopathologic scores of oral mucositis were lower in the eucalyptus gel group than those of the calendula and control groups (p<0.05). Also, a lower malondialdehyde level and higher myeloperoxidase and glutathione activities were detected in the eucalyptus group in comparison to the calendula and control groups (p<0.001). The thickness of the mucosa and submucosa increased in the eucalyptus group. The numerical density of the fibroblast and the volume density of the collagen significantly increased in the eucalyptus group. In conclusion, the use of eucalyptus hydroalcoholic extract may be associated with reduced intensity of oral mucositis, diminished concentration of malondialdehyde, increased activity of myeloperoxidase and glutathione, increased volume of mucosa and submucosa, increased fibroblast and collagen in the induced oral mucositis in golden hamsters undergoing 5-FU consumption.

Types of sterilization in feed containing different lipidic sources for golden hamster (Mesocricetus auratus)

The Golden hamster has been gaining significance as a new experimental biomodel, finding use as a reliable diagnostic tool in biomedical research and for zoonosis. Authentic data in terms of digestibility, interactions among raw materials and essential nutrients, besides the influence exerted by various sterilization processes on animal behavior remain unclear. We aimed to assess the influence of sterilization, via autoclaving and irradiation, of pellet feeds prepared using salmon or linseed oil on the digestibility and plasma biochemical parameters in Golden hamsters. Randomized evaluations were conducted on 36 adult male Golden hamsters (Mesocricetus auratus), distributed in six treatments and six replications, namely: common salmon oil; radiated salmon; autoclaved salmon; common linseed oil; radiated linseed and autoclaved linseed. A remarkable effect of the sterilization was evident on the digestibility and protein solubility of the feed, which was lower for autoclaved diets. There was also a significant effect on blood parameters. Animals fed diets containing linseed oil showed lower blood glucose compared to the others. Thus, the inference reached was that while salmon and linseed oil can be used in laboratory hamster feeds, autoclaving disturbs the nutritional quality of the rations.

Aggression and plasma testosterone in male golden hamsters (Mesocricetus auratus) in response to encounters with receptive vs. nonreceptive females

Exposure to sexual stimuli can lead to increased aggression in male mammals, but it is unclear whether the aggression is related to the receptiveness of the females. Interactions with receptive females elicit testosterone (T) pulses that are important for sexual behaviors. We investigated the effects of male–female interactions on subsequent aggressive behaviors and T responses in the golden hamster (Mesocricetus auratus (Waterhouse, 1839)). Three groups (n = 18, 17, and 18) of males were exposed to receptive females, nonreceptive females, and blank (control), respectively. Then, we randomly chose eight animals from each group and measured their aggression toward an unfamiliar male conspecific; the remaining 29 males were used for a T assay (to avoid effects of aggression on T levels). The results show that interactions with females led to significantly higher male aggression and T levels than were found in control males. The increased aggression was not related to the receptiveness of the females, but receptive females elicited higher levels of T in males than nonreceptive females. Our findings suggest that the elevated aggression following the sexual encounter may serve to defend the female, by enhancing the ability of males to exclude other males from the vicinity of females, whereas the post-encounter T release may serve to assist mating behaviors and reproductive success.