MD Anderson Researchers Uncover Immune Signals Linked to Antidepressants

MD Anderson Researchers Uncover Immune Signals Linked to Rapid-Acting Antidepressants

Treatment-resistant depression occurs when symptoms persist despite multiple rounds of traditional antidepressant treatments or talk therapy. While rapid-acting treatments like ketamine and psilocybin can alleviate symptoms quickly for some patients, clinicians have historically lacked reliable biomarkers to predict who will respond.

The study was published in Nature and co-led by Gregory Jones, M.D., assistant professor of Psychiatry at MD Anderson Cancer Center. Depression is a common challenge for individuals facing a cancer diagnosis, making the search for effective biological markers particularly critical.

Shared Neuroimmune Pathways Across Diverse Therapies

To better understand the biological mechanisms at play, researchers analyzed the effects of multiple rapid-acting antidepressants in both laboratory models and data from a previous clinical trial. Although agents such as ketamine and psychedelics affect the brain through distinct receptors and trigger different subjective experiences, the research team discovered that they ultimately converge on shared biological pathways.

Ketamine and psychedelics affect the brain in different ways subjectively, but our findings suggest that they eventually end up in some of the same neuroimmune pathways, Jones said according to MD Anderson Cancer Center. By studying blood signals and brain activity together, researchers can better understand how the body and brain may work in tandem to respond to antidepressants.

Specifically, investigators observed that several rapid-acting antidepressants trigger a common set of immune-related molecular changes in brain cells. Researchers also noted matching immune-related shifts in patient blood samples, alongside related alterations in brain electrical activity following ketamine treatment.

Predicting Treatment Response Through Immune Biomarkers

The investigation revealed distinct baseline differences between patients who responded to ketamine and those who did not. Participants who responded successfully showed lower interleukin-15 (IL-15) pathway activity and higher B cell signaling prior to treatment. Notably, both of these baseline measures reversed after therapy in patients who experienced symptom relief.

These observations suggest that rapid antidepressant responses may involve restoring a biological balance between IL-7 and IL-15, which subsequently creates downstream effects on B cells and electrical brain activity.

Complementary laboratory analyses utilizing bulk RNA sequencing on iPSC-derived cortical neurons further demonstrated time-dependent and overlapping genetic effects of rapid-acting treatments, including (2R,6R)-HNK, psilocybin, LSD, and DOI, across six-hour and 24-hour intervals as detailed in Nature. Most hallmark signaling pathways were downregulated at six hours but upregulated at 24 hours following drug administration.

Next Steps and Study Limitations

While the discoveries offer promising avenues for future psychiatric care, study authors emphasize that the current findings are exploratory. Consequently, they require rigorous validation through larger, prospective clinical studies.

Future research will focus on determining whether IL-15, IL-7, and related immune biomarkers can reliably predict treatment outcomes before therapy begins. Scientists also aim to investigate whether directly targeting these pathways could successfully improve or extend patient responses to rapid-acting antidepressants. The research received partial funding from the National Institutes of Health.