Longitudinal analysis of memory T follicular helper cells and antibody response following CoronaVac vaccination (preprint)

The inactivated vaccine CoronaVac is one of the most widely used COVID-19 vaccines globally. However, the longitudinal evolution of the immune response induced by CoronaVac remains elusive compared to other vaccine platforms. Here, we recruited 88 healthy individuals that received 3 doses of CoronaVac vaccine. We longitudinally evaluated their polyclonal and antigen-specific CD4+ T cells and neutralizing antibody response after receiving each dose of vaccine for over 300 days. Both the 2nd and 3rd dose of vaccination induced robust spike-specific neutralizing antibodies, with a 3rd vaccine further increased the overall magnitude of antibody response, and neutralization against Omicron sub-lineages B.1.1.529, BA.2, BA.4/BA.5 and BA.2.75.2. Spike-specific CD4+ T cell and circulating T follicular helper (cTFH) cells were markedly increased by the 2nd and 3rd dose of CoronaVac vaccine, accompanied with altered composition of functional cTFH cell subsets with distinct effector and memory potential. Additionally, cTFH cells are positively correlated with neutralizing antibody titers. Our results suggest that CoronaVac vaccine-induced spike-specific T cells are capable of supporting humoral immunity for long-term immune protection.

Radix Tetrastigma flavonoids inhibit the migration and promote the apoptosis of A549 cells both in vitro and in vivo

The main flavonoid components of Radix Tetrastigma (RTF) were extracted and characterized by high performance liquid chromatography. In vitro, RTF suppressed the viability of A549 cells, and inhibited the invasion and migration of A549 by damaging the lamellipodium and the structure of F-actin. In vivo, compared to the model group, RTF inhibited the growth of tumor volumes in nude mice, and decreased the weight of tumor. To uncover the inner mechanism, the proliferation-related proteins: PCNA, Ki67 and the apoptosis-related proteins: caspase-3, caspase-9, Bax and Bcl-2 were examined by immunohistochemical and western blot analysis. Compared to the model group, the production levels of PCNA, Ki67 and Bcl-2 were significantly down-regulated by RTF, and the expression levels of caspase-3, caspase-9 and Bax were markedly up-regulated. Comprehensively, RTF could suppress the proliferation of A549 and promote the apoptosis of A549, suggesting RTF as a potential resource to fight against non-small cell lung cancer (NSCLC).