Nature: Scientists have found out why chloroquine's treatment of COVID-19 is ineffective.

Today, Nature published a new study by a European research team in the form of accelerated previews.
researchers found that while chloroquine can prevent new coronavirus from invading cells in common renal cell line, it is not effective in lung cell line to prevent new coronavirus from invading cells.
researchers say the findings highlight the importance of testing the effectiveness of potential therapies using cell linelines that simulate pulmonary cortical cells.
know that the new coronavirus is the new coronavirus through the surface of the virus s protein and the cell surface of the ACE2 body binding, guide the new coronavirus into the cell.
previous in-body experiments, researchers used a renal cell line called Vero as a cell model to test the effectiveness of chloroquine and hydroxychloroquine in suppressing new coronavirus infections.
they found chloroquine and hydroxychloroquine to inhibit the invasion of Vero cell line by the new coronavirus, a finding that prompted chloroquine/hydroxychloroquine to be tested in several clinical trials to treat COVID-19 patients.
, it has not been clarified why chloroquine/hydroxychloroquine inhibits the invasion of Vero cells by the new coronavirus.
study, published in Nature, researchers found that vero cell line did not express a serine protease called TMPRSS2.
the role of this protease expressed in pulmonary endocrine cells is to help process prickly proteins, which are important steps before binding to ACE2 binds.
when the researchers expressed the TMPRSS2 protease in Vero cell line, they found that chloroquine/hydroxychloroquine was no longer able to inhibit the new coronavirus from invading these Vero cells, which express TMPRSS2.
, when researchers examined the role of chloroquine/hydroxychloroquine in a lung cell line called Calu-3, they found that chloroquine/hydroxychloroquine's ability to inhibit the new coronavirus from invading the cell was also very limited.
means that chloroquine/hydroxychloroquine is unlikely to stop new coronavirus infection cells in human lung endoskin cells that express TMPRSS2.
chloroquine/hydroxychloroquine (dark blue and light blue data points) can prevent new coronavirus from entering cells in Vero cells, but it does not work well in Vero cells and Caru-3 cells that express TMPRSS2 (Photo Source: Reference: Reference) How does chloroquine/hydroxychloroquine prevent the new coronavirus from infecting Vero cells? In addition to using TMPRSS2, the researchers believe that the new coronavirus can also treat hedgehog proteins with a cysteine protease called cathepsin L.
chloroquine/hydroxychloroquine can affect the function of tissue protease L by altering the pH of cells.
Vero cells do not express TMPRSS2, but they do express tissue protease L.
, chloroquine/hydroxychloroquine can show strong viral inhibition in Vero cells.
researchers say they are repeating the experiment in primary lung cells, but because of the high levels of TMPRSS2 expressed in human lung cells, they warn that chloroquine/hydroxychloroquine may not be effective in stopping the new coronavirus from invading.
also consistent with the results of clinical trials.
reference: s1. Hoffmann et al., (2020). Chloroquine does not infected of human lung cells with SARS-CoV-2. Nature, original title: Frontiers . . . Nature: Scientists have found the reason why chloroquine's treatment of COVID-19 is ineffective! It turned out to be because of this protease.