A carotenoid that's already widely available in fruit and vegetables, and as a supplement, has been found to bolster the cancer-fighting abilities of immune cells, making it a promising new candidate that could help shrink tumors during immunotherapy treatment.
Following years of work investigating natural compounds to enhance cancer therapies, researchers from the University of Chicago have discovered that zeaxanthin – a carotenoid that promotes eye health – boosts the activity of the immune system's CD8+ T cells, which seek and destroy cancerous tumor cells.
“We were surprised to find that zeaxanthin, already known for its role in eye health, has a completely new function in boosting anti-tumor immunity,” said senior author Jing Chen, Professor of Medicine at the University of Chicago. “Our study show that a simple dietary nutrient could complement and strengthen advanced cancer treatments like immunotherapy.”
Screening a large blood nutrient library – the range of nutrients measured in blood tests – the researchers found that zeaxanthin stabilizes and strengthens the formation of T-cell receptor (TCR) structures on CD8+ T cells when the immune cells encounter cancer growths. This then activates stronger signaling within cells, enhancing T-cell activation, cytokine production and tumor-killing abilities. Basically, it equips the immune cells with what they need to mount a fiercer fight.
In mouse models, animals given a diet high in zeaxanthin exhibited significantly slower tumor growth. When combined with immune checkpoint inhibitors – the breakthrough immunotherapy that prevents the immune system from attacking healthy cells – the T cells' tumor-fighting capacity was further enhanced. When tested on human T cells, which had been developed to recognize a range of tumor antigens, zeaxanthin bolstered the immune cells' power in killing off melanoma, multiple myeloma and glioblastoma cells.
“Our data show that zeaxanthin improves both natural and engineered T-cell responses, which suggests high translational potential for patients undergoing immunotherapies,” Chen said.
Zeaxanthin is a type of xanthophyll – a yellow carotenoid pigment found broadly in nature – already available as a supplement for eye health, and found in dark leafy greens like kale, as well as orange peppers, mango and corn. And because zeaxanthin has a well-known safety profile, it could be easily incorporated into existing cancer immunotherapy treatment regimens.
While clinical trials will be required to see if the positive results from the lab and mice studies can be replicated in cancer patients, zeaxanthin is a promising new avenue of research aimed at making immunotherapy more successful. Earlier studies have found that a range of natural compounds – like those found in licorice and beans – can potentially improve the body's response to cancer cells.
“Our findings open a new field of nutritional immunology that looks at how specific dietary components interact with the immune system at the molecular level,” Chen said. “With more research, we may discover natural compounds that make today’s cancer therapies more effective and accessible.”
The research was published in the journal Cell Reports Medicine.
Source: University of Chicago
