by In a recent study published in Nature, researchers developed a library of blood nutrient molecules and screened them to find dietary components that influence anti-tumor immunity.
Study: CD8 trans-vaccine acid reprograms+ T cells and anti-tumor immunity. Image Credit: Anusorn Nakdee/Shutterstock.com
Background
Dietary nutrients are closely related to human physiological processes because they provide energy, biosynthesize building blocks, and act as mediators.
However, the mechanisms by which circulating human nutrients affect certain physiological pathways are unclear, and further research is needed.
About the study
In this study, the researchers investigated the effect of diet-derived trans-vaccinic acid (TVA) on cytotoxic T-lymphocyte functions and anti-tumor immunity in the in vivo arrangements.
The researchers examined the effect of several nutrients on human T-lymphocyte cells using a blood nutrient molecule library screening technique.
All cell lines (Jurkat T, human Plat-E, B16-OVA murine melanoma cancer cells, B16F10 murine melanoma cancer cells, E0771 breast cancer cells, and LLC1 Lewis lung carcinoma cells, and MC38 murine colorectal adenocarcinoma cells) were validated using short genomic. tandem repeat (STR) profiling.
The first screen was used to identify foods that promote activation of Jurkat T lymphocytes induced by cluster of differentiation 23 (CD23) and CD28 antibodies. Screen 1b identified nutrients that reverse programmed cell death ligand 1 (PD-L1)-dependent depletion of Jurkat T cells stably expressing programmed cell death protein 1 (PD-1) produced by PD-L1-expressing cocultures H596 human lung cancer cells.
The team performed magnetic bead purification to identify CRISPR-associated protein 9 (Cas9)-expressing OT-I cells from the spleen and peripheral lymph nodes of Cas9-OT-I animals.
Commercial chimeric antigen receptor (CAR) T lymphocyte therapy recipients provided serum samples. The researchers infected Jurkat T lymphocytes with a preformed PD-1-expressing lentivirus and then selected 2.0 g/mL puromycin to produce PD-1-expressing Jurkat T lymphocytes.
Western blotting revealed the presence of PD-1. The study involved feeding Jurkat T lymphocytes with a nutrient library for two days, then stimulating them with anti-CD3 and anti-CD28 antibodies for 12 hours. Interleukin-2 (IL-2) levels were measured using enzyme-linked immunosorbent assays (ELISA).
In the second screen, Jurkat T lymphocytes were cocultured with PD-1-expressing cells for 60 hours and then stimulated with anti-CD23 and anti-CD28 antibodies for 12 hours. Gpr43fl/fl, Gpr43 -/ -, and Cd8acre murine animals were bred to produce Gpr43 – / flCd8acre conditional knockout mice (Gpr43 / flCd8acre) and to develop a Gpr43 / animal tumor model.
The team obtained cheek bleeds on days 3.0, 12, and 18 and performed flow cytometry to assess CD8+ T cell depletion efficiency using antibodies targeting non-competing CD8 epitopes (BV711 anti-mouse CD8).
In vitro [13C] fatty acid tracing, seahorse fatty acid oxidation assay, measured calcium level (Ca2+) of cytotoxic T lymphocytes (CD8+), clustered regularly interspaced short palindromic repeat (CRISPR) editing of mice OT-I cells, pull-down assay for trans protein -identification of TVA complexes, a co-culture assay with Blinatumomab, and a CAR-T cell expansion assay were performed. TVA levels were quantified by nuclear magnetic resonance (NMR) spectroscopy.
Results
TVA, a trans fatty acid component of human milk, is derived primarily from ruminant foods such as lamb, beef and dairy. Humans and mice convert only 12% to 19% of dietary derived TVA into ruminic acid. TVA inhibited the immunoregulatory G protein-coupled receptor 43 (GPR43), a molecule stimulated by its SCFA ligands.
TVA stimulated the cyclic AMP (cAMP)-protein kinase A (PKA)-cAMP-binding element protein (CREB) axis, enhancing the function of cytotoxic T lymphocytes, indicating that TVA is fed, rather than gut microbiota-derived SCFAs within the host. host-extrinsic reprogramming pathway for cytotoxic T lymphocytes.
TVA reduced Gαi-coupled GPR43 activity and elevated cAMP levels, antagonizing the effect of short-chain fatty acid molecules on cyclic AMP to enhance the function of effector-type cytotoxic T lymphocytes. TVA promoted anti-tumor immunity by upregulating CD8+ T lymphocytes, which selectively enhanced the function of stimulated cytotoxic T lymphocytes.
The enhancement of cytotoxic T lymphocyte function induced by TVA was regulated by the GPCR-CREB pathway, with positive feedback increasing the expression of PKA and CREB at the gene level. TVA activity required CREB and could enhance cytotoxic T lymphocyte function and anti-tumor immunity in vivo. CREB inhibition impaired the effect of dietary TVA on anti-tumor immunity.
TVA’s improved T-cell-based treatments. In the case of cytotoxic T lymphocytes, the GPR43-CREB pathway may be cell specific. TVA therapy, for example, enhanced synthesis of interleukin-2 by T helper lymphocytes (CD4+) but did not affect the generation of effector molecules such as tumor necrosis factor (TNF-α) and interferon-gamma (IFN-γ) or the proliferation or apoptosis of T helper lymphocytes.
Thus, the effects of dietary TVA on helper T lymphocytes were small compared to those on cytotoxic T lymphocytes, which may be due to the low expression of GPR43 in helper T lymphocytes.
Conclusion
Overall, the results of the study showed that dietary trans vaccinic acid enhances the effect of cytotoxic T lymphocyte activity and anti-tumor immunity in the in vivo arrangements.
Exogenous TVA, in contrast to endogenous SCFAs derived from gut microbes that act as GPR43 agonists, reprogrammed CD8+ T lymphocytes through extrinsic regulation to inactivate GPR43.
The results of the study contribute to a better understanding of the molecular links between nutrition and human pathology, with implications for future research on the function of circulating nutrients in health and disease.
Further research is needed to improve understanding of GPR43 downstream effector pathways and to elucidate underlying processes.
