N-Acetylcysteine: A potential therapeutic agent for SARS-CoV-2
MEDICAL HYPOTHESES
Authors: Poe, Francis L.; Corn, Joshua
Abstract
COVID-19, a respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues to spread across the globe. Predisposing factors such as age, diabetes, cardiovascular disease, and lowered immune function increase the risk of disease severity. T cell exhaustion, high viral load, and high levels of TNF-alpha, IL1 beta, IL6, IL10 have been associated with severe SARS-CoV-2. Cytokine and antigen overstimulation are potentially responsible for poor humoral response to the virus. Lower cellular redox status, which leads to pro-inflammatory states mediated by TNF-alpha is also potentially implicated. In vivo, in vitro, and human clinical trials have demonstrated N-acetylcysteine (NAC) as an effective method of improving redox status, especially when under oxidative stress. In human clinical trials, NAC has been used to replenish glutathione stores and increase the proliferative response of T cells. NAC has also been shown to inhibit the NLRP3 inflammasome pathway (IL1 beta and IL18) in vitro, and decrease plasma TNF-alpha in human clinical trials. Mediation of the viral load could occur through NAC's ability to increase cellular redox status via maximizing the rate limiting step of glutathione synthesis, and thereby potentially decreasing the effects of virally induced oxidative stress and cell death. We hypothesize that NAC could act as a potential therapeutic agent in the treatment of COVID-19 through a variety of potential mechanisms, including increasing glutathione, improving T cell response, and modulating inflammation. In this article, we present evidence to support the use of NAC as a potential therapeutic agent in the treatment of COVID-19.
Interleukin-6 trans-signaling is a candidate mechanism to drive progression of human DCCs during clinical latency
NATURE COMMUNICATIONS
Authors: Werner-Klein, Melanie; Grujovic, Ana; Irlbeck, Christoph; Hoffmann, Martin; Koerkel-Qu, Huiqin; Lu, Xin; Treitschke, Steffi; Koestler, Cacilia; Botteron, Catherine; Weidele, Kathrin; Werno, Christian; Polzer, Bernhard; Kirsch, Stefan; Guzvic, Miodrag; Warfsmann, Jens; Honarnejad, Kamran; Czyz, Zbigniew; Feliciello, Giancarlo; Blochberger, Isabell; Grunewald, Sandra; Schneider, Elisabeth; Haunschild, Gundula; Patwary, Nina; Guetter, Severin; Huber, Sandra; Rack, Brigitte; Harbeck, Nadia; Buchholz, Stefan; Ruemmele, Petra; Heine, Norbert; Rose-John, Stefan; Klein, Christoph A.
Abstract
Although thousands of breast cancer cells disseminate and home to bone marrow until primary surgery, usually less than a handful will succeed in establishing manifest metastases months to years later. To identify signals that support survival or outgrowth in patients, we profile rare bone marrow-derived disseminated cancer cells (DCCs) long before manifestation of metastasis and identify IL6/PI3K-signaling as candidate pathway for DCC activation. Surprisingly, and similar to mammary epithelial cells, DCCs lack membranous IL6 receptor expression and mechanistic dissection reveals IL6 trans-signaling to regulate a stem-like state of mammary epithelial cells via gp130. Responsiveness to IL6 trans-signals is found to be niche-dependent as bone marrow stromal and endosteal cells down-regulate gp130 in premalignant mammary epithelial cells as opposed to vascular niche cells. PIK3CA activation renders cells independent from IL6 trans-signaling. Consistent with a bottleneck function of microenvironmental DCC control, we find PIK3CA mutations highly associated with late-stage metastatic cells while being extremely rare in early DCCs. Our data suggest that the initial steps of metastasis formation are often not cancer cell-autonomous, but also depend on microenvironmental signals. Metastatic dissemination in breast cancer patients occurs early in malignant transformation, raising questions about how disseminated cancer cells (DCC) progress at distant sites. Here, the authors show that DCCs in bone marrow are activated via IL6-trans-signaling and thereby acquire stemness traits relevant for metastasis formation.