Chemokine dynamics after mRNA vaccination

Since the COVID-19 pandemic, mRNA-based vaccines have gained prominence and opened up new opportunities for vaccine development. Rapid and long-lasting immune responses to antigens are crucial for the success of vaccines. Chemokines, cytokines, and chemokine receptors play an essential role in this process; thus, in this study, we aimed to investigate their regulation and the resulting immune cell profile during mRNA-based SARS-CoV2 vaccination.

SARS-CoV-2 neutralizing antibody titers were examined by ELISA. Chemokine abundance before and after 2nd dose of the mRNA-1273 vaccine on time points d-1, d+1/2, d+3/4, and d+7 was examined in serum samples using bead-based immunoassays. In addition, flow cytometric analysis of blood samples was performed to characterize chemokine receptor expression on several immune cell populations associated with vaccination success.

Our results demonstrated that mRNA-1273 vaccination increased serum levels of type 1 (IFNγ), type 2 (IL-4), other pro-inflammatory cytokines (IL-1α, IL-1β) and chemokines (CXCL9, CXCL10, CXCL11, CCL2, CCL4) between day 1 and day 4 post vaccination. Vaccination altered chemokine receptor expression on various cell types. Despite high interindividual differences, enhanced expression was observed for CXCR5 on activated CD4 T cells. Furthermore, CCR5 expression was increased on RBD⁺ B cells after vaccination, while CCR1, CCR2, CCR4, CCR5, and CXCR5 were elevated on different monocyte subsets. A notable finding was the positive correlation between elevated CXCR4 expression on RBD⁺ B cells and a high SARS-CoV-2 neutralizing antibody (NAb) titer ratio.

We here demonstrate a dynamic, cell-specific chemokine regulation early after mRNA booster vaccination. This chemokine modulation likely facilitates an efficient induction of innate immune cell and adaptive T cell responses.