Tissue Distribution of ACE2 Protein in Syrian Golden Hamster (Mesocricetus auratus) and Its Possible Implications in SARS-CoV-2 Related Studies

Abstract

The Syrian golden hamster (Mesocricetus auratus) has recently been demonstrated as a clinically relevant animal model for SARS-CoV-2 infection. However, lack of knowledge about the tissue-specific expression pattern of various proteins in these animals and the unavailability of reagents like antibodies against this species hampers these models’ optimal use. The major objective of our current study was to analyze the tissue-specific expression pattern of angiotensin-converting enzyme 2, a proven functional receptor for SARS-CoV-2 in different organs of the hamster. Using two different antibodies (MA5-32307 and AF933), we have conducted immunoblotting, immunohistochemistry, and immunofluorescence analysis to evaluate the ACE2 expression in different tissues of the hamster. Further, at the mRNA level, the expression of Ace2 in tissues was evaluated through RT-qPCR analysis. Both the antibodies detected expression of ACE2 in kidney, small intestine, tongue, and liver. Epithelium of proximal tubules of kidney and surface epithelium of ileum expresses a very high amount of this protein. Surprisingly, analysis of stained tissue sections showed no detectable expression of ACE2 in the lung or tracheal epithelial cells. Similarly, all parts of the large intestine were negative for ACE2 expression. Analysis of tissues from different age groups and sex didn’t show any obvious difference in ACE2 expression pattern or level. Together, our findings corroborate some of the earlier reports related to ACE2 expression patterns in human tissues and contradict others. We believe that this study’s findings have provided evidence that demands further investigation to understand the predominant respiratory pathology of SARS-CoV-2 infection and disease.

Quantitative proteomics of hamster lung tissues infected with SARS‐CoV‐2 reveal host factors having implication in the disease pathogenesis and severity

“…Sections were deparaffinized, rehydrated, and subjected to antigen retrieval treatment and serum blocking as reported earlier 22 . Sections were incubated with SARS‐CoV‐2 N protein (Nucleocapsid) (#11‐2003; Abgenex, 1:200) or SOD2/Mn‐SOD (#NB100‐1992; Novus biologicals, 1:100) in a humidified chamber overnight at 4°C.…”

“…Collected tissues were processed and sectioned as reported previously 22,24 . Sections were deparaffinized, rehydrated, and subjected to antigen retrieval (Vector Laboratories) treatment for 20 minutes followed by blocking the endogenous peroxidase with 3% hydrogen peroxide in methanol for 20 minutes.…”

“…Formalin-fixed tissues were further processed and sectioned for Hematoxylin and Eosin (H&E), Immunohistochemistry (IHC), and Immunofluorescence analysis (IF) as reported earlier. 22 2.4 | Hematoxylin and Eosin (H&E) staining and lung pathology scoring Tissues from multiple lobes of all the animals were processed and stained with H&E staining. Stained lung sections were assigned with different numbers and evaluated in a blinded fashion.…”

Male bias in ACE2 basic science research: missed opportunity for discovery in the time of COVID-19

“…In contrast, a study of Ace2 mRNA in the lung of old (15–17 mo) hamsters showed males had over threefold higher levels of ACE2 than the old females ( 74 ). The authors also found Ace2 mRNA was 37-fold higher in old male hamsters compared with young (2–4 mo) males.…”

3D visualization of SARS-CoV-2 infection and receptor distribution in Syrian hamster lung lobes display distinct spatial arrangements

“…ACE2 and TMPRSS2 are expressed in a wide variety of tissues and have been analyzed using several different genetic techniques 7–9 . Suprisingly a common denominator in these studies is the high expression of these proteins in extrapulmonary tissues, whereas the virus mainly infects the respiratory tract.…”