ABSTRACT
CD45, the predominant transmembrane tyrosine phosphatase in leukocytes, is required for the efficient induction of T cell receptor signaling and activation. We recently reported that the CD45-intracellular signals in peripheral blood mononuclear cells (PBMCs) of triple negative breast cancer (TNBC) patients are inhibited. We also reported that C24D, an immune modulating therapeutic peptide, binds to CD45 on immune-suppressed cells and resets the functionality of the immune system via the CD45 signaling pathway. Various studies have demonstrated that also viruses can interfere with the functions of CD45 and that patients with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are immune-suppressed. Given the similarity between the role of CD45 in viral immune suppression and our findings on TNBC, we hypothesized that the C24D peptide may have a similar "immune-resetting" effect on PBMCs from COVID-19 patients as it did on PBMCs from TNBC patients. We tested this hypothesis by comparing the CD45/TCR intracellular signaling in PBMCs from ten COVID-19 patients vs. PBMCs from ten healthy volunteers. Herein, we report our findings, demonstrating the immune reactivating effect of C24D via the phosphorylation of the tyrosine 505 and 394 in Lck, the tyrosine 493 in ZAP-70 and the tyrosine 172 in VAV-1 proteins in the CD45 signaling pathway. Despite the relatively small number of patients in this report, the results demonstrate that C24D rescued CD45 signaling. Given the central role played by CD45 in the immune system, we suggest CD45 as a potential therapeutic target.
ABSTRACT
Patients receiving chemotherapy are at high risk for severe infections and complications such as acute respiratory syndrome. The most commonly used adjuvant chemotherapy protocols (docetaxel-cyclophosphamide every 3 weeks or the dose-dense regimen, doxorubicin-cyclophosphamide every 2 weeks followed by paclitaxel) incorporate granulocyte-colony stimulating factor (G-CSF). G-CSF is routinely administered to prevent chemotherapy-associated neutropenia but often results in significant neutrophilia. The present case describes a patient with breast cancer who was successfully treated for severe COVID-19 respiratory syndrome while under adjuvant chemotherapy (docetaxel-cyclophosphamide) treatment and long-term G-CSF support. In addition, the potential effect of G-CSF on the respiratory deterioration of the patient given its cardinal role in innate inflammation and, accordingly, the cytokine storm associated with COVID-19 was described. The case described in the present study indicated how solutions to the immunity challenges faced when treating a patient with chemotherapy may be the source of a larger problem within the coronavirus COVID-19 pandemic.