Antiviral Immunity and in vitro Pathophysiological Responses to SARS-CoV-2 Spike Proteins in Severe Coronary Artery Disease Patients

Background: Despite recent advances, the pathophysiological mechanisms of COVID-19 in patients with severe coronary artery disease (CAD) remain unclear. The two major aims of this study are to investigate the functional phenotypes of MAIT cells (Mucosal Associated Invariant T cells) as well as T cells in the peripheral blood of preoperative CABG patients (Coronary Artery Bypass Grafting) and the in-vitro pathological responses of the PBMCs from these patients to SARS-CoV-2 spike proteins.

Methods: 54 preoperative CAD patients and 52 normal controls (NCs) were recruited. Flow cytometry (FACS) was employed to investigate the circulating frequencies of different subtypes of MAIT cells (CD4+, CD8+ and CD4-CD8-), and T cell subtypes, representing activation (CD25, CD69) and inhibition status (PD-1, Tim-3) and the expression of SARS-Cov-2 cognate receptors (ACE2, CD147) on granulocytes and mononuclear cells of CAD patients and controls. Furthermore, Immunofluorescence microscopy and FACS were employed to quantify apoptotic markers, such as Caspase 3/7 and Annexin-V/7AAD, respectively, and the T cell proliferation assay using CFSE staining. Plasma MAIT cell-associated cytokines, IL-18, IL-7, IL-22, IFN-γ, TNF-α, were quantified using ELISA.

Results: MAIT cells frequencies, CD8+ MAIT cells and CD4- MAIT cells were significantly decreased, while CD4-CD8- double negative MAIT cells were increased in CAD patients when compared with NC. The cytokine receptor’s IL-18R expression on CD8+, CD8-, CD4+ MAIT cells in CAD patients was significantly decreased. We also observed significantly increased blood circulating CD4+PD1+T cells and CD8+CD25+ T cells among the CAD group. In general, CAD patients exhibited higher rate of apoptosis in comparison to NCs. The impact of viral spike proteins along with IL-6 (50 pg/mL) was investigated for inducing apoptosis on PBMCs. Upon exposure to spike proteins and IL-6 or IL-6 alone, PBMCs of CAD patients exhibited higher apoptosis rates than those of NCs (p = 0.0079 and p = 0.0238 respectively).

Conclusion: The functionality of the MAIT cells were impaired among CAD patients. Increased state of exhaustion (CD4+PD1+ T cells) and circulating regulatory type T cells (CD8+CD25+ T cells) indicates immune unresponsiveness and inhibition attributes, respectively, with higher potency for apoptosis. These results pinpoint the existence of a dysregulated antiviral immunity among CAD patients and an inability to combat a potential SARS-CoV-2 infection.

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Artikel online veröffentlicht:
13. Februar 2024