COVID-19 increases the risk of severe illness and poor vaccination response among patients with kidney disease. Oxidative stress may play a role, and it can be measured by assessing serum free thiols (R-SH, sulfhydryl groups). In a post hoc analysis of the RECOVAC IR observational study, Larissa E. van Eijk and colleagues studied the association between serum free thiols and kidney patients’ ability to mount a humoral immune response to SARS-CoV-2 vaccination.
The team measured serum free thiol concentrations in patients with CKD stages 4 and 5 (G4/5; n=46), on dialysis (n=43), kidney transplant recipients (KTR; n=73), and controls (n=50). They analyzed baseline serum free thiol and interferon-γ-induced protein-10 (a biomarker of the interferon response) for associations with seroconversion rates and SARS-CoV-2 spike-specific immunoglobulin G concentrations after two doses of the mRNA-1273 vaccine.
The researchers found that albumin-adjusted serum free thiol concentrations were much lower in patients with CKD G4/5 (P<.001), on dialysis (P<.001), and KTR (P<.001) compared with controls. After full vaccination, seroconversion rates were greatly lessened in KTR (52.1%) and were significantly associated with albumin-adjusted free thiols (OR, 1.76; P=.033). However, the significance did not remain after adjustment for mycophenolate mofetil use, hemoglobin, and estimated glomerular filtration rate (eGFR; odds ratio [OR], 1.49; P=.241).
In sum, transplant recipients had suboptimal serological responses to SARS-CoV-2 vaccination, which is inversely associated with serum R–SH. This indicates systemic oxidative stress. The association could be at least partially involved in transplant recipients’ poor serological response to SARS-CoV-2 vaccination.
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