Astragaloside IV and ginsenoside Rb1 combination improves diabetic foot ulcer healing by downregulating the IRF1-ZBP1 axis in keratinocytes

For millions of people living with diabetes, a small cut on the foot can become a life-altering wound that refuses to close. This condition, known as a diabetic foot ulcer, is not merely a surface injury; it is a deep biological stalemate. In a healthy body, the healing process is a coordinated sequence where immune cells rush to the site to clear debris and fight infection, then step aside to let new skin grow. In diabetes, high blood sugar throws this process into chaos. The immune cells, particularly neutrophils, become overactive and confused. Instead of helping, they release a toxic cloud of inflammatory signals and self-destruct in ways that damage the very tissue they are meant to repair. This creates a vicious cycle of inflammation and cell death that prevents the skin from knitting back together, often leading to severe complications or amputation. Scientists have long searched for a way to break this cycle, looking for agents that can calm the immune system and protect the skin cells without causing harm.

A team of researchers at Nanchang University in China has identified a promising approach using a combination of two natural compounds found in traditional Chinese medicine: astragaloside IV, derived from the astragalus root, and ginsenoside Rb1, found in ginseng. In a study published recently, the researchers demonstrated that when these two substances are used together in a specific proportion, they can significantly speed up the healing of diabetic foot ulcers in rats and protect skin cells in the laboratory. The key to their success lies in how they interact with the body's cellular machinery. The researchers found that high blood sugar triggers a specific type of cell death called PANoptosis, a process where cells die in a way that simultaneously releases inflammatory signals, worsening the wound. The study shows that the combination of the two drugs works by turning down the activity of a specific protein called ZBP1, which acts as a switch for this destructive process. By stopping this switch, the drugs allow the skin cells to survive and the wound to heal.

To understand how this works, the scientists first created a model of the problem in a dish. They took human skin cells, known as keratinocytes, and exposed them to high levels of glucose to mimic the environment of a diabetic foot. Under these conditions, the cells began to die rapidly through apoptosis, pyroptosis, and necroptosis—three different forms of programmed cell death that, in this context, merge into the single destructive event of PANoptosis. The researchers then tested various concentrations of astragaloside IV and ginsenoside Rb1, both alone and in combination. They discovered that while each drug offered some protection on its own, they worked best together. Specifically, a mixture where the amount of astragaloside IV was to the amount of ginsenoside Rb1 in a ratio of two to three produced the strongest protective effect. This combination kept the skin cells alive, reduced the release of toxic inflammatory chemicals, and lowered the levels of oxidative stress, which is essentially a form of rusting damage caused by unstable molecules in the cell.

The researchers then moved from the laboratory dish to living animals to see if these results held true in a complex biological system. They created a diabetic foot ulcer model in rats by inducing diabetes and then creating a precise one-centimeter wound on the animal's back. They treated these wounds with the drug combination, with each drug alone, or with a saline solution as a control. Over twelve days, the wounds treated with the combination of the two drugs closed significantly faster than those in any other group. When the researchers examined the tissue under a microscope, they saw that the combination treatment led to thicker, healthier new skin tissue and a denser network of new blood vessels, which are essential for delivering oxygen and nutrients to a healing wound. Crucially, they also observed a marked reduction in the infiltration of neutrophils, the immune cells that had been causing so much damage. The treatment effectively stopped these cells from releasing their toxic nets and inflammatory signals, allowing the healing process to proceed.

To uncover the molecular mechanism behind this healing, the team investigated how the drugs interacted with the proteins inside the cells. They used computer modeling to predict how the drug molecules might fit into the structures of various proteins involved in cell death. The models suggested that both drugs could bind tightly to ZBP1, a protein that acts as a sensor for danger signals and triggers the PANoptosis cascade. To confirm this physical interaction, the researchers performed experiments where they heated the proteins or exposed them to enzymes that break them down. They found that when the drugs were present, the ZBP1 protein became more stable and resistant to degradation, indicating that the drugs were indeed latching onto it. Further experiments showed that the drugs also reduced the levels of another protein called IRF1, which normally sits upstream of ZBP1 and tells it to turn on. By suppressing IRF1, the drugs prevented the activation of ZBP1, effectively cutting off the signal that told the skin cells to self-destruct.

The study went a step further to prove that ZBP1 was the critical target. The researchers used genetic tools to lower the amount of ZBP1 in the skin cells, mimicking the effect of the drugs. When ZBP1 was reduced, the cells became much more resistant to the damaging effects of high sugar, just as they were when treated with the drugs. However, when the researchers tried to add the drugs to cells that already had low levels of ZBP1, the drugs provided no additional benefit. This confirmed that the drugs work specifically by targeting ZBP1; if the target is already gone, the drugs have nothing to do. Conversely, when the researchers forced the cells to produce extra ZBP1 or extra IRF1, the cells suffered severe damage, but the drug combination was still able to reverse this damage. This demonstrated that the drugs are powerful enough to override the destructive signals even when the system is pushed toward cell death.

The findings suggest that the combination of astragaloside IV and ginsenoside Rb1 offers a dual strategy for treating diabetic foot ulcers. First, it directly protects the skin cells by stopping the specific molecular switch, ZBP1, that triggers their self-destruction. Second, by calming this cellular alarm, it indirectly reduces the chaotic activity of the immune system, preventing the neutrophils from releasing the inflammatory clouds that delay healing. The study provides a clear molecular explanation for why these two natural compounds work better together than apart, identifying a specific pathway that can be targeted to restore the body's ability to heal. While the research was conducted in cells and rats, and the authors note that further studies are needed to confirm safety and efficacy in humans, the work offers a compelling new direction for developing treatments that address the root causes of chronic non-healing wounds rather than just managing the symptoms.