Ulcerative Colitis (UC) is a chronic inflammatory bowel disease (IBD) that causes long-term inflammation and ulcers in the lining of the colon and rectum. The disease itself is fundamentally a state of immune system dysregulation, where the body’s immune cells mistakenly attack the inner lining of the large intestine. This abnormal immune response leads to chronic inflammation, which is the source of symptoms such as bloody diarrhea, abdominal pain, and urgency.
The immune system in a person with untreated UC is not typically considered weak; rather, it is overactive, specifically targeting the gut tissue. This misdirected activity involves an increase in certain immune cells and the overproduction of inflammatory proteins such as tumor necrosis factor-alpha (TNF-alpha). Therefore, having UC alone does not make a person immunocompromised in the traditional sense. The complex answer lies in the medications used to bring this hyper-active immune response under control.
Immunocompromised Defined
The term “immunocompromised” refers to a condition where the body’s immune system is weakened and has a reduced ability to fight off infections, pathogens, and certain diseases. This state is often called immunosuppression, especially when caused by medications or treatments. People who are immunocompromised face a higher risk of contracting various infections, including common colds, influenza, and shingles.
In a clinical context, the degree of immune compromise can range from mild to severe, affecting how a person interacts with routine illnesses and their required vaccination schedules. A compromised immune system may cause illnesses that are typically mild for most people to become severe or long-lasting. People in this category must take extra precautions to protect their health from environmental pathogens.
Drug Classes Causing Immune Suppression
The reason many individuals with Ulcerative Colitis are considered immunocompromised is due to the medications necessary to treat their disease. These treatments work by purposefully dampening the immune system’s overactive response in the colon. The medications used to achieve this can be categorized into several classes, each carrying a different degree of immunosuppression risk.
Corticosteroids
Corticosteroids, such as prednisone, are powerful anti-inflammatory agents used to quickly induce remission during a flare-up by broadly suppressing the immune system. They alter gene transcription and suppress cytokine production, providing rapid relief by significantly reducing inflammation. Because of their broad effect and potential for side effects, they are generally used for short-term suppression and are not intended for long-term maintenance therapy.
Immunomodulators
Immunomodulators like azathioprine or 6-mercaptopurine (6-MP) are often used for long-term control to maintain remission and reduce the need for steroids. These drugs work by interfering with the synthesis of genetic material, which slows the proliferation of immune cells. This mechanism leads to sustained, moderate immune suppression and requires regular blood testing to monitor liver, kidney, and bone marrow function.
Biologics and Small Molecules
Biologics and small molecules represent the most advanced category of targeted therapies, and their use often leads to a clinically immunocompromised state. Biologics, such as anti-TNF agents (like infliximab) and integrin antagonists, are monoclonal antibodies that target specific proteins or pathways responsible for inflammation. This targeted approach is highly effective at healing the colon lining but still carries an infection risk because it blocks certain components of the immune defense.
Janus kinase (JAK) inhibitors, a type of small molecule drug, work by blocking a family of enzymes inside immune cells that send inflammatory signals. These drugs directly interrupt the intracellular signaling pathway that drives the inflammatory process in UC. The use of these advanced therapies means a person is actively modulating their immune system, necessitating precautions against opportunistic infections.
Managing Infection Risk
For UC patients on immunosuppressive therapy, proactive management of infection risk is an ongoing part of their care. Maintaining open communication with both the gastroenterologist and the primary care physician is necessary to coordinate care. The healthcare team needs to be aware of all medications to properly assess the risk of serious or opportunistic infections.
Simple hygiene practices, such as frequent handwashing, are effective daily defense measures against infection. Avoiding close contact with individuals who are actively sick, particularly during peak cold and flu seasons, can reduce exposure risk. Patients should also discuss a plan with their doctor for when to temporarily hold their immunosuppressive medication if they develop a severe infection.
Vaccination is an important consideration, but not all vaccines are suitable for those on these therapies. Inactivated or recombinant vaccines, which use killed viruses or only parts of a virus, are generally considered safe and highly recommended, including the annual flu shot. Live vaccines, which contain a weakened form of the living virus, are often prohibited and should not be administered while on immunosuppressive drugs.