A current iScience journal research reviews that cell-surface vimentin features as a co-receptor for the entry of the extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) into host cells to facilitate an infection. Thus, focusing on vimentin could present a singular technique for stopping the coronavirus illness 2019 (COVID-19).
Research: Vimentin is a vital ACE2 co-receptor for SARS-COV-2 in epithelial cells. Picture Credit score: Design_Cells / Shutterstock.com
Background
The emergence and fast unfold of SARS-CoV-2 have considerably impacted international well being and the economic system. As of November 2, 2022, SARS-CoV-2 has contaminated over 636 million worldwide and claimed greater than 6.59 million lives.
The entry of SARS-CoV-2, which is a single-stranded enveloped ribonucleic acid (RNA) virus), into host cells is a key issue for its infectivity and illness pathogenesis. To this finish, SARS-CoV-2 primarily depends on its receptor binding area (RBD) inside the spike protein to bind to the cell-surface angiotensin-converting enzyme 2 (ACE2) receptor for viral attachment. This subsequently permits the virus to enter endosomes and fuse with host-lysosomal membranes.
Though COVID-19 primarily causes respiratory signs, ACE2 is sparsely expressed all through the respiratory tract. This means that extra cofactors could compensate and allow the spike protein and host receptor interactions.
Vimentin is a sort III intermediate filament cytoskeletal protein expressed inside and on the floor of varied varieties together with fibroblasts, endothelial cells, macrophages, melanocytes, Schwann cells, and lymphocytes. Extra not too long ago, researchers have reported that vimentin seems to work together with the SARS-CoV-2 spike protein.
Concerning the research
Within the present research, the researchers used quite a lot of epithelial cell traces, together with Vero E6, human colon epithelial cells (Caco-2), and human alveolar basal epithelial cells (A549), to find out the expression of ACE2, TMPRSS288, and vimentin . Within the subsequent step, the researchers assessed whether or not vimentin and ACE2 expression ranges in Vero E6, Caco-2, and A549 cells have been associated to the entry of SARS-CoV-2 into cells.
The researchers additionally examined whether or not viral an infection altered vimentin expression on the cell floor. Utilizing Western blot evaluation following SARS-CoV-2 an infection, vimentin within the cell supernatant was assessed for co-localization with SARS-CoV-2.
Vimentin was additionally evaluated for its means to inhibit viral an infection by pre-treating cells for half-hour with withaferin A (WFA), which is a steroidal lactone that binds and causes vimentin aggregation in vitro. Quantitative polymerase chain response (qPCR) assay was used to quantify vimentin aggregation, whereas immunofluorescence and confocal microscopy supplied visualization of this course of.
Research findings
Epithelial cells have been discovered to precise various portions of vimentin and ACE2. Vero E6 cells, for instance, expressed increased ranges of ACE2 as in comparison with Caco-2 and A549 cells. Conversely, each Vero E6 and Caco-2 cells expressed comparable ranges of TMPRSS2 that have been considerably increased than the expression of this cell floor protein in A549 cells.
Vimentin was expressed at very low ranges in Caco-2 cells as in comparison with Vero E6 and A549 cells. Notably, Vero E6 cells exhibited the next degree of vimentin expression as in comparison with A549 cells; nevertheless, cell floor expression of vimentin was highest in A549 cells.
Following an infection with SARS-CoV-2, viral uptake in Vero E6 ranges was best between ten minutes and two hours. Though SARS-CoV-2 uptake was equally excessive in Caco-2 cells at ten minutes, these ranges didn’t rise over the course of two hours. The uptake of SARS-CoV-2 was a lot much less in A549 cells.
Taken collectively, these findings recommend that the expression of vimentin on the cell floor could favor the elevated uptake of SARS-CoV-2 in Vero E6 cells as in comparison with the opposite epithelial cell traces. Additional evaluation of SARS-CoV-2 an infection in Vero E6 cells revealed that vimentin expression elevated on the cell floor after two and thirty minutes.
In the meantime, there was no interplay between vimentin and ACE2 in uninfected Vero E6 cells, thus indicating that vimentin could operate as a co-receptor for SARS-CoV-2 an infection.
Pre-treatment with WFA previous to SARS-CoV-2 an infection in Vero E6 cells didn’t considerably affect viral replication in cells. These findings reveal that though vimentin promotes SARS-CoV-2 cell an infection, it’s not important for viral replication in cells.
Nonetheless, pre-treatment with WFA diminished cell dying in SARS-CoV-2 contaminated cells, thus suggesting that the inhibition of vimentin could scale back the probability of virus-induced cell dying. Moreover, pre-treatment with anti-vimentin diminished the expression of interleukin 6 (IL-6) by 15-fold, in addition to CCL5 and CSCL10 by 10-fold, thus indicating that the inhibition of vimentin might also restrict the inflammatory response to SARS-CoV-2 an infection.
Notably, when these experiments have been repeated with the SARS-CoV-2 Omicron variant, comparable outcomes have been noticed. Thus, mutations inside the Omicron spike protein don’t seem to affect the interplay between SARS-CoV-2 and vimentin throughout an infection.
Journal reference:
- Arrindell J, Abou Atmeh P, Jayet L, et al. (2022). Vimentin is a vital ACE2 co-receptor for SARS-COV-2 in epithelial cells. IScience. doi:10.1016/j.isci.2022.105463
