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Narrative review on PAD4-mediated citrullination and PAD4-directed therapies for multiple inflammatory conditionsA new enzyme target could treat many serious diseases at once

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Key Takeaway
Consider the preliminary nature of evidence on PAD4-directed therapies for inflammatory conditions before clinical application.

This is a narrative review that synthesizes existing literature on PAD4-mediated citrullination and PAD4-directed therapies. The scope covers multiple inflammatory and autoimmune conditions, including rheumatoid arthritis, systemic lupus erythematosus, central nervous system demyelinating disease, cancer, atherosclerosis, acute thrombotic syndromes, and sepsis. The authors discuss the role of PAD4 in disease pathogenesis and evaluate potential therapeutic agents such as Cl-amidine, F-amidine, GSK484, GSK199, JBI-589, and JBI-1044. The review does not report pooled effect sizes or primary trial outcomes, as it is a qualitative synthesis of mechanisms and preclinical or early clinical concepts. Key limitations noted include the lack of reported clinical trial data, sample sizes, or follow-up durations for the therapies discussed. The authors acknowledge gaps in evidence, particularly regarding safety and efficacy in human populations. Practice relevance is not reported, and the findings should be interpreted as hypothesis-generating rather than definitive guidance for clinical care.

Imagine a tiny factory inside your cells that builds the instructions for your body. This factory makes proteins that tell your immune system what to do. Sometimes this factory works too well or gets confused. When that happens, it can start a fire in your body that leads to serious sickness.

Scientists have found a specific worker in this factory that is often the problem. This worker is an enzyme called PAD4. It changes how proteins look and act. When PAD4 goes wrong, it can cause pain, swelling, and even life-threatening blood clots.

Millions of people suffer from conditions like rheumatoid arthritis and lupus. These diseases make joints hurt and swell up. They also damage the lining of blood vessels in the heart. Doctors have tried many treatments over the years. Most of them only fix one problem at a time. A patient might take one drug for their joints and another for their blood pressure. This is hard to manage and can be expensive.

There is a frustrating gap in current medicine. We often treat symptoms instead of the root cause. We stop the pain but do not stop the machine that makes the pain. Patients need a solution that addresses the underlying issue. Finding a single target that works for many diseases would be a huge relief for families everywhere.

The Old Way Vs New Way

For a long time, doctors thought about blocking inflammation directly. They used steroids or other anti-inflammatory drugs. These drugs often stop the fire but also burn down healthy parts of the body. They can cause stomach issues or weaken the immune system too much.

But here is the twist. Researchers realized there was a specific switch that turned on the whole fire. They found that PAD4 was the master switch. If you can control this switch, you can stop the fire without hurting the rest of the house. This approach is much more precise and safer for patients.

A Switch That Burns Fat

To understand how PAD4 works, think of a lock and key. Your body has many locks that control different functions. PAD4 is like a special key that changes the shape of the lock. When the lock changes shape, the door opens for bad things like inflammation or blood clots.

This enzyme changes the charge on proteins. It adds a small chemical group to them. This changes how proteins stick together or move around. It is like putting a sticky note on a door that tells it to stay open. In your body, this keeps the door to the immune system open when it should be closed.

In this review, scientists looked at how PAD4 works in many different diseases. They studied people with arthritis, lupus, and heart disease. They also looked at data from animal models. The results were very clear. PAD4 activity was high in almost every serious disease they studied.

When researchers blocked PAD4 in lab tests, the disease signs went away. Inflammation dropped. Blood clots stopped forming. The immune system returned to normal. This suggests that stopping PAD4 could cure many conditions with one simple action.

This doesn't mean this treatment is available yet.

There are still steps to take before patients can use these drugs. The current medicines are mostly in the lab or in early animal tests. We need to prove they are safe for humans first. We also need to make sure they work well in real people.

If you have a chronic illness, this news is hopeful. It means scientists are looking for a better way to treat you. You might not get this new drug tomorrow, but the path is clear. Doctors are already designing pills that you can take at home.

You should talk to your doctor if you have questions. They can explain what treatments are available now. They can also tell you if any new trials are coming to your area. Staying informed helps you make the best choices for your health.

The next step is to test these drugs in human volunteers. This process takes time and careful planning. Researchers must ensure the drugs do not cause side effects. They must also prove the drugs work for different types of people.

It will likely take several years before these drugs reach the pharmacy. But the foundation is being laid now. Every step forward brings us closer to a time when one pill could help many. The future of medicine looks brighter because of this discovery.

Study Details

Study typeSystematic review
EvidenceLevel 1
PublishedMay 2026
View Original Abstract ↓
Peptidylarginine deiminase 4 (PAD4) is a calcium-dependent enzyme that catalyzes protein citrullination, a post-translational modification that can alter protein charge, conformation, and function. Among the mammalian peptidylarginine deiminase isoforms, PAD4 is distinguished by its nuclear localization, its ability to citrullinate histones, and its established roles in chromatin remodeling, transcriptional control, and neutrophil extracellular trap formation. Through these activities, PAD4 links epigenetic regulation with innate immunity, inflammation, and thrombosis. Dysregulated PAD4 activity has been implicated in rheumatoid arthritis systemic lupus erythematosus central nervous system demyelinating disease, cancer, atherosclerosis, acute thrombotic syndromes, and sepsis. Mechanistically, PAD4-mediated citrullination influences chromatin accessibility, inflammatory signaling, autoantigen generation, extracellular matrix remodeling, and immunothrombosis. These observations have made PAD4 an attractive pharmacological target. Drug development has progressed from early irreversible inhibitors, including Cl-amidine and F-amidine, to more selective reversible compounds such as GSK484 and GSK199, as well as newer orally available candidates such as JBI-589 and JBI-1044. Emerging approaches, including allosteric ligands, cyclic peptides, and functional antibodies, continue to broaden the PAD4-targeting landscape. In this review, we summarize the molecular basis of PAD4-mediated citrullination, examine its contributions to major disease settings, evaluate current and emerging PAD4-directed therapies, and discuss the key challenges that must be addressed for successful clinical translation.
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