Intake of herring oils resulted in lower pulmonary concentration of angiotensin-converting enzyme 2 but did not affect blood pressure in male obese Zucker fa/fa rats

BACKGROUND: Angiotensin-converting enzyme 2 (ACE2) is a receptor for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and is involved in blood pressure regulation and inflammation through the renin-angiotensin system. Fish intake is associated with lower risk of severe coronavirus disease 2019 (Covid-19), but the effect of fish oil intake on pulmonary ACE2 has not been investigated. OBJECTIVES: Primarily, to investigate the effect of consuming fish oils containing cetoleic acid (CA, C22:1n-11), EPA and DHA on the pulmonary concentration of ACE2 in rats. Secondary outcomes include inflammatory markers in lungs and blood pressure. METHODS: Thirty male obese Zucker fa/fa rats aged 7 weeks were fed regular diets containing herring oil and soyabean oil (HERO), a CA concentrate from herring oil and soyabean oil (CECO), or soyabean oil as the sole lipid source (Control diet) for 5 weeks. The HERO diet contained 0.70 wt% CA and 0.35 wt% EPA+DHA, and the CECO diet contained 1.40 wt% CA and 0.24 wt% EPA+DHA. Blood and tissues were collected at endpoint, and blood pressure was measured at baseline and after 33 days. Data were analysed using one-way ANOVA followed by Fisher's least significant difference test when appropriate. RESULTS: Compared to Controls, HERO and CECO groups had lower pulmonary protein concentrations of ACE2 (32 and 24 %, respectively), TNFα (31 and 28 percent, respectively) and monocyte chemotactic protein 1 (34 and 17 %, respectively), all comparisons P<0.05, with no effect on blood pressure (P>0.05). CONCLUSION: The lower pulmonary ACE2 concentration indicates that herring oils could reduce cell entry of SARS-CoV2 without detrimental increase in blood pressure. Herring oils also reduced protein concentrations of inflammatory markers in lungs.