Fluoxetine as an anti-inflammatory therapy in SARS-CoV-2 infection

Abstract

Hyperinflammatory response caused by infections such as Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) increases organ failure, intensive care unit admission, and mortality. Cytokine storm in patients with Coronavirus Disease 2019 (COVID-19) drives this pattern of poor clinical outcomes and is dependent upon the activity of the transcription factor complex nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappaB) and its downstream target gene interleukin 6 (IL6) which interacts with IL6 receptor (IL6R) and the IL6 signal transduction protein (IL6ST or gp130) to regulate intracellular inflammatory pathways. In this study, we compare transcriptomic signatures from a variety of drug-treated or genetically suppressed (i.e. knockdown) cell lines in order to identify a mechanism by which antidepressants such as fluoxetine demonstrate non-serotonergic, anti-inflammatory effects. Our results demonstrate a critical role for IL6ST and NF-kappaB Subunit 1 (NFKB1) in fluoxetine's ability to act as a potential therapy for hyperinflammatory states such as asthma, sepsis, and COVID-19.

Keywords: Antidepressants; COVID-19; Coronavirus disease 2019; Cytokine IL6; Cytokine storm; Fluoxetine; Inflammation; Nuclear factor kappa B subunit 1; SARS-CoV-2; SSRIs; Selective serotonin reuptake inhibitors; Sepsis; Severe acute respiratory syndrome coronavirus 2; Transcription factor NF-κB.

Graphical abstract

Fig. 1

Experimental Design and Analytical Workflow. We generated differential gene expression signatures produced by fluoxetine, paroxetine, bupropion, or dexamethasone drug treatments across a variety of concentrations and treatment durations compared to control, untreated, wild-type cells. We also generated differential gene expression signatures produced by genetic knockdown of inflammatory genes related to the initiation and maintenance of IL6-mediated cytokine storm. Again, these signatures are in relation to control, untreated, wild-type cells. We then compared the drug treatment signatures with the genetic knockdown signatures to quantify similarity using concordance scores. When a drug treatment signature is highly concordant with a genetic knockdown signature, it generates a value approaching +1 and allows us to surmise that this drug and this genetic knockdown induce equivalent changes in gene expression. When no significant similarities exist, the concordance score approaches zero. When a drug treatment signature is highly discordant with a genetic knockdown signature, it generates a value approaching −1 and allows us to surmise that this drug and this genetic knockdown induce inverted changes in gene expression.

Fig. 2

Quantification of similarity between fluoxetine, dexamethasone, bupropion, or paroxetine drug-treatment signatures and IL6ST or NFKB1 gene knockdown signatures. (A and B) Analyses of differential gene expression signatures elicited by fluoxetine, dexamethasone, bupropion, or paroxetine treatments compared to differential gene expression signatures elicited by (A) IL6ST knockdown or (B) NFKB1 knockdown. Similarity is quantified as concordance score. The maximum absolute concordance scores from all comparands are reported. Means derived from cell lines are also reported. (C−F) Heatmaps and corresponding data tables representing full concordance analyses comparing drug-treated cells and C, (E) matched IL6ST knockdown or D, (F) matched NFKB1 knockdown cell lines. For comprehensive coverage, the heatmaps and corresponding data tables represent additional concordance scores derived from cell lines lacking data set(s) within our inclusion parameters for one or more comparison (black boxes in heatmap; gray boxes in data table). Means and standard deviations (SD), derived from all available comparand cell lines (N) are also presented.

Fig. 3

Pathway: NF-kappaB, IL6, sIL6R, IL6ST, and Cytokine Storm. The transcription factor NF-kappaB binds the IL6 gene to induce transcriptional expression of the proinflammatory cytokine. Pro-inflammatory trans-signaling-mediated responses involve IL6 proteins binding to soluble IL6 receptors (sIL6R) which activates the IL6 signal transduction protein (IL6ST or gp130). IL6ST activation is integral to many intracellular cytokine-mediated inflammatory pathways including the cytokine storm / cytokine release syndrome driving many of the negative clinic outcomes associated with COVID-19.