by In a recent study published in Nature, researchers developed a library of nutrient molecules in the blood and screened to find dietary components that affect anti-tumor immunity.
Study: Transvaccenic acid reprograms CD8+ T cells and antitumor immunity. Image Credit: Anusorn Nakdee/Shutterstock.com
Background
Dietary nutrients are closely related to human physiological processes, as they provide energy, biosynthesize basic components, and act as mediating substances.
However, the methods by which human nutrients circulate impact particular physiological pathways are unclear, warranting further investigation.
About the study
In the present study, the researchers explored the impact of dietary-derived transvaccinic acid (TVA) on the effector functions of cytotoxic T lymphocytes and antitumor immunity in the live settings.
The researchers examined the impact of various nutrients on human T lymphocyte cells using a screening technique based on a library of blood nutrition molecules.
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 colorectal adenocarcinoma cells murine MC38) were validated using short genomic cells. Tandem repeat (STR) profiling.
The first test was used to identify foods that promoted Jurkat T cell activation triggered by cluster of differentiation 23 (CD23) and CD28 antibodies. Test 1b identified nutrients that reverse programmed cell death ligand 1 (PD-L1)-dependent depletion of Jurkat T cells that stably express programmed cell death protein 1 (PD-1) produced by cancer cells. cocultured human lung H596 expressing PD-L1. .
The team performed magnetic bead purification to identify OT-I cells expressing CRISPR-associated protein 9 (Cas9) from the spleen and peripheral lymph nodes of Cas9-OT-I animals.
Recipients of commercial chimeric antigen receptor (CAR) T cell therapy provided serum samples. The researchers infected Jurkat T cells with a premade lentivirus that expresses PD-1 and then chose 2.0 g/ml of puromycin to produce PD-1-expressing Jurkat T cells.
Western blotting revealed the presence of PD-1. The study involved feeding Jurkat T cells a nutritional library for two days and then stimulating them with anti-CD3 and anti-CD28 antibodies for 12 hours. Interleukin-2 (IL-2) levels were measured by enzyme-linked immunosorbent assays (ELISA).
In the second selection, Jurkat T cells 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 develop the Gpr43/ animal tumor model.
The team obtained cheek bleeds on days 3.0, 12, and 18 and performed flow cytometry to assess the efficacy of CD8+ T cell depletion using antibodies targeting non-competitive CD8 epitopes (BV711 anti-mouse CD8).
in vitro [13C] fatty acid tracking, seahorse fatty acid oxidation assay, measured calcium (Ca2+) level of cytotoxic T lymphocytes (CD8+), clustered regularly interspaced short palindromic repeats (CRISPR) editing of mouse OT-I cells, Pull-down assay to identify cross-linked proteins. TVA complexes, Blinatumomab co-culture assay, and CAR-T cell expansion assay were performed. TVA levels were quantified by nuclear magnetic resonance (NMR) spectroscopy.
Results
TVA, a trans fatty acid constituent of human milk, is predominantly derived from ruminant foods such as lamb, beef, and dairy. Humans and mice convert only 12% to 19% of dietary-derived TVA to rumenic acid. TVA inhibited immunoregulatory G protein-coupled receptor 43 (GPR43), a molecule stimulated by its SCFA ligands.
TVA triggered the cyclic AMP (cAMP)-protein kinase A (PKA)-response element binding protein (CREB) axis, enhancing cytotoxic T lymphocyte function, indicating that dietary TVA, rather than SCFA derived from the gut microbiota within the host, is an extrinsic host reprogramming pathway for cytotoxic T lymphocytes.
TVA attenuated Gαi-coupling GPR43 activity and elevated cAMP levels, antagonizing the influence of short-chain fatty acid molecules on cyclic AMP to enhance effector-type cytotoxic T lymphocyte function. TVA promoted antitumor immunity through the regulation of CD8+ T cells, selectively enhancing the function of stimulated cytotoxic T cells.
TVA-induced enhancement of cytotoxic T lymphocyte function was regulated by the GPCR-CREB pathway, with positive feedback increasing PKA and CREB expression at the genetic level. TVA activity required CREB and could improve cytotoxic T lymphocyte function and antitumor immunity live. CREB inhibition antagonized the impact of dietary TVA on antitumor immunity.
TVA improved T cell-based treatments. For cytotoxic T lymphocytes, the GPR43-CREB pathway could be cell type specific. TVA therapy, for example, enhanced the synthesis of interleukin-2 by T helper (CD4+) cells, but did not affect the generation of effector molecules such as tumor necrosis factor alpha (TNF-α) and interferon gamma ( IFN-γ) or the proliferation or apoptosis of T helper lymphocytes.
Therefore, the effects of dietary TVA on helper T cells were minor compared to those on cytotoxic T cells, which could be due to the low expression of GPR43 on helper T cells.
Conclusion
Overall, the study findings showed that dietary transvaccenic acid increases the activity of effector cytotoxic T lymphocytes and antitumor immunity in the live settings.
Extraorganismal TVA, unlike intraorganismal SCFAs derived from gut microbes that function as GPR43 agonists, reprogrammed CD8+ T cells through extrinsic regulation to inactivate GPR43.
The study findings contribute to a better understanding of the molecular links between nutrition and human pathophysiology, with implications for future research on the role of circulating nutrients in health and disease.
Further research is required to improve understanding of the downstream effector pathways of GPR43 and elucidate the underlying processes.
