Biologic correlates of beneficial convalescent plasma therapy in a COVID-19 patient reveal disease resolution mechanisms

Abstract

Background: While the biomarkers of COVID-19 severity have been thoroughly investigated, the key biological dynamics associated with COVID-19 resolution are still insufficiently understood.

Main body: We report a case of full resolution of severe COVID-19 due to convalescent plasma transfusion in a patient with underlying multiple autoimmune syndrome. Following transfusion, the patient showed fever remission, improved respiratory status, and rapidly decreased viral burden in respiratory fluids and SARS-CoV-2 RNAemia. Longitudinal unbiased proteomic analysis of plasma and single-cell transcriptomics of peripheral blood cells conducted prior to and at multiple times after convalescent plasma transfusion identified the key biological processes associated with the transition from severe disease to disease-free state. These included (i) temporally ordered upward and downward changes in plasma proteins reestablishing homeostasis and (ii) post-transfusion disappearance of a particular subset of dysfunctional monocytes characterized by hyperactivated Interferon responses and decreased TNF-α signaling.

Conclusions: Monitoring specific subsets of innate immune cells in peripheral blood may provide prognostic keys in severe COVID-19. Moreover, understanding disease resolution at the molecular and cellular level should contribute to identify targets of therapeutic interventions against severe COVID-19.

Figure 1.. Timeline of the clinical course.

(A) Day 0 indicates the date of the COVID-19 symptom onset. The days post-onset at which COVID-19 related symptoms, hospitalization course, RT-PCR test results, convalescent plasma transfusions, and interventions took place are indicated. (B–E) Longitudinal analysis of (B) maximum body temperature, (C) C- Reactive protein (CRP) in plasma, (D) SARS-CoV-2 RNA detection in plasma by qRT-PCR, (E) Titers for IgG against SARS-CoV-2 Spike Receptor binding domain (RBD). The y axis in each panel indicates the corresponding measurement unit. In all panels, the x axis indicates the day numbering as depicted in panel A. In panels B-C, the timeline in the x axis highlights the first hospitalization (days 14–25) and the second hospitalization (days 33–61), since the corresponding measurements were performed only in the hospital. In all panels, the vertical arrows indicate convalescent plasma transfusions from anonymous donor (1^st) and from a patient’s relative (2^nd and 3^rd). The asterisk indicates the drop in viral load recorded at day 57 (in panel A). In panel D, Ct, cycle threshold; N, SARS-CoV-2 nucleocapsid gene; RdRP, SARS-CoV-2 RNA-dependent RNA polymerase gene.

Figure 2.. Unsupervised hierarchical clustering and principal component analysis (PCA) of cytokines and proteins in the recipient’s plasma before and after convalescent plasma transfusion.

(A-B) Unsupervised hierarchical clustering was performed on cytokine profile and proteome using MATLAB. Vertical arrows in panel B mark the set of proteins that decrease (orange arrow) or increase (green arrow) following transfusion. (C-D) PCA was conducted on plasma cytokine profile (C) and proteome (D). (E-F) The top 10 enriched KEGG pathways for proteins that decrease (orange bars) (referred to as module A in Fig. S3 and in the text) or increase (green bars) (module B in Fig. S3 and in the text) using EnrichR Pathway Analysis.