Researchers Identify Potential Immune Link to Alzheimer’s Disease

Breakthrough in Alzheimer’s Research

A team of scientists, led by Professor Minah Suh at Sungkyunkwan University, has discovered a new approach to enhance the brain’s immune response and mitigate abnormal nerve-cell activity linked to Alzheimer’s disease. This study was conducted in collaboration with IMNEWRUN and Professor Ho-Keun Kwon’s team at Yonsei University College of Medicine.

Role of Microglia in Alzheimer’s

The focus was on microglia, the brain’s native immune cells. These cells typically act as the first line of defense, detecting damage and maintaining a healthy brain environment. However, Alzheimer’s disease compromises this function, and nerve cells exhibit abnormal activity.

Published in Science Advances, the study links these issues to changes in two immune-regulating proteins: PD-1 and PD-L1. In Alzheimer’s model mice, researchers observed elevated PD-1 levels in microglia and PD-L1 in astrocytes, which play a crucial role in maintaining brain health.

The Experimental Approach

Researchers administered an antibody blocking PD-L1 directly into the brains of these model mice. Advanced microscopy techniques revealed that microglia restored their capacity to respond effectively to damage, and excessive neuron activity was reduced.

Implications of the Study

Dr. John Showalter, Linus Health’s COO, commented that the study strengthens evidence of the immune system’s significant involvement in Alzheimer’s and dementia. He noted, “Individuals vaccinated for shingles show lower dementia incidence.” This indicates a direct role of immune cells, particularly microglia, in disease processes, increasing interest in immune-focused research.

Notably, modifying PD-L1 within the brain proved more effective than systemic antibody administration. This suggests a connection between disrupted immune signaling and changes in the brain’s damage response and neuron activity.

The study aligns with a broader shift in Alzheimer’s research, with inflammation and immune-modulating drugs representing 18% of clinical trials, competing with anti-amyloid drugs at 16%.

Limitations and Future Research

Though promising, blocking PD-L1 is not confirmed to treat or cure Alzheimer’s in humans. Conducted on Alzheimer’s-like mice, the results suggest potential rather than established treatment. Showalter highlights challenges in translating these findings into practical human treatments, particularly in safely delivering antibodies to patients.

Further studies are essential to verify similar effects in humans, emphasizing the complexity of administering medication directly into the brain and spinal cord fluid.

Reference: Taeyoung Park et al., “Targeting glial PD-1/PD-L1 restores microglial homeostasis and reduces neuronal hyperactivity in an Alzheimer’s disease model,” Science Advances (2026). DOI: 10.1126/sciadv.adx0731