New Paper (Therapeutic): Cyclosporin A inhibits the replication of diverse coronaviruses

Questions to answer about each paper:

In this study, Wilde et al. showed that CsA had a significant inhibitory effect on SARS-CoV and HCoV-229E replication. A depletion of CypA or CypB did not affect infectivity though, indicating that the effect of CsA was not mediated by its CypA inhibition.

Study question(s) being investigated:

How many/what drugs/combinations are being considered?

They mainly analyze Cyclosporin A (CsA).

What are the main hypotheses being tested?

Does Cyclosporin A inhibit SARS-CoV, HCoV-299E, and mouse hepatitis (MHV) in vitro?
Is CypA inhibition responsible for the CsA-induced inhibition?

Study population:

What is the model system (e.g., human study, animal model, cell line study)?

In vitro, they used (1) Vero E6 and HEK293/ACE2 cells for SARS-CoV, (2) Huh7 cells for HCoV-299E, and (3) 17CL1 cells for MHV.

What is the sample size? If multiple groups are considered, give sample size for each group (including controls).

They used different concentrations of CsA in each of the four cell line groups mentioned above (i.e. 0, 0.25, 0.5 ... 32, 64 µM).

Treatment assignment:

Provide other relevant details about the design.

In the context of CD147-mediated cell fusion of SARS-CoV-2, it's worth to mention that both Vero E6 and HEK293 cells express CD147.

Outcome Assessment:

Describe the outcome that is assessed and whether it is appropriate.

SARS-CoV-GFP expression was traced via GFP 18h after infection.
Wildtype SARS-CoV and SARS-CoV-GFP expression were further evaluated using fluorescence microscopy, western blotting, and plague assay 16h after infection.

Are outcome measurements complete?

Wildtype SARS-CoV measurements were done using a limited group of 4 - 32 µM CsA.

Are outcome measurements subject to various kinds of bias?

Each subgroup is directly comparable.

Statistical Methods Assessment:

What methods are used for inference?

No inference methods are applied.

Are the methods appropriate for the study?

It seems appropriate for an in vitro study.

Are adjustments made for possible confounders?

No adjustments are made for different treatment times but each group covered a wide sample range.

Results Summary:

What is the estimated association?

They provide mean values of quadruplicate samples and standard deviations.

What measures of confidence or statistical significance are provided?

Statistical measures are not provided but the data is clear enough for interpretation without p values (for concentrations >= 16 µM).

Interpretation of results for study population:

Can we make a causal interpretation for the individuals in the study of drug -> outcome, such as "taking drug A improves likelihood of survival twofold over taking drug B."

16 µM of CsA show a knockout effect on SARS-CoV cell cultures immediately after infection.

Are there identified side effects or interactions with other drugs?

CsA did not affect cell viability significantly in any concentrations they used.

Are there specific subgroups with different findings?

Low to median concentrations of CsA seemed to have an enhancing effect on SARS-CoV replication but not HCoV-299E replication. There could be a biphasic effect.

Extrapolation of conclusions to other groups of individuals not specifically included in the study:

Summary of reliability

This is another study indicating a significant effect of CsA not only on SARS-CoV but other viruses as well. The jump of 8 to 16 µM made a vast difference in the inhibitory effect on all viruses they tested. Below 8 µM, the results are very inconclusive or ineffective indicating a concentration-dependent competition with viral proteins or delayed response. A progression of viral load was not measured to evaluate this question, unfortunately. Outstanding in the context of SARS-CoV-2 is the finding that SARS-CoV did not depend on CypA for infection. CypA depletion could even enhance infectivity in a mild manner. However, they did not combine CsA and CypA knockdown in an experiment. But the indication is clearly that the effect of CsA is not mediated by CypA or CypB.

Progress

Check off the components as they are completed. If the component is not applicable, check the box as well.

[x] 1-2 sentences introducing the study and its main findings
[x] Describe How many/what drugs/combinations are being considered
[x] Describe the model system
[x] What is the sample size?
[x] What countries/regions are considered
[x] What is the age range, gender, other relevant characteristics
[x] Describe study setting
[x] Describe other specific inclusion-exclusion criteria
[x] Describe how treatments are assigned
[x] Describe randomization (or not) and other relavent details about the design
[x] Describe the outcome that is assessed and whether it is appropriate.
[x] Describe whether the outcome measurements are complete
[x] Are outcome measurements subject to various kinds of bias?
[x] Describe methods used for inference
[x] Describe whether the methods are appropriate for the study
[x] Are adjustments made for possible confounders?
[x] Describe the estimated association
[x] What measures of confidence or statistical significance are provided?
[x] Describe whether a causal interpretation can be made
[x] Are there identified side effects or interactions with other drugs?
[x] Are there specific subgroups with different findings?
[x] If the study is an animal study, which animal and how relevant is that model?
[x] If it is a human study, what characteristics of the study population may support/limit extrapolation?
[x] Summary of reliability

greenelab / covid19-review