Ulcerative colitis

Definitions & Key takeaways

Ulcerative colitis is a type of inflammatory bowel disease that causes inflammation and ulcers in the mucosa and submucosa of the large intestine, specifically in the colon and rectum. The cause of the disease is believed to be autoimmune in origin, with cytotoxic T cells destroying the cells lining the walls of the large intestine, leaving behind eroded areas or ulcers. Environmental stimuli and genetic predisposition also play a role. Diagnosis typically requires colonoscopy and radiological imaging. Treatment includes anti-inflammatory medications, drugs that suppress the immune system, and biologic treatments. In severe cases, colectomy may be necessary.

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Inflammatory bowel disease can cause inflammation in the small and large intestine, in other words...inflammation of the bowel.
Colitis refers specifically to inflammation in the colon, or the large intestine. Ulcerative colitis is a type of inflammatory bowel disease that tends to form ulcers along the inner-surface or lumen of the large intestine, including both the colon and the rectum.
These ulcers are spots in the mucosa where the tissue has eroded away and left behind open sores or breaks in the membrane.
Sometimes there is a flare which means that new damage has occurred, and then there are periods of remission when the tissue starts to heal up.
Ulcerative colitis is actually the most common type of inflammatory bowel disease, not that there are that many, but this one causes inflammation and ulcers in the mucosa and submucosa of the large intestine only, which is an important point that sets it apart from Crohn disease, another inflammatory bowel disease.
Now although certain environmental factors like diet and stress were once thought to be the culprit behind these ulcers forming in the gut, now it’s thought that these are more secondary, meaning they seem to make symptoms worse, but ulcerative colitis is now ultimately thought to be autoimmune in origin.
In fact, cytotoxic T cells from the immune system are often found in the epithelium lining the colon, so the thought is that inflammation and ulceration in the large intestine is caused by T cells destroying the cells lining the walls of the large intestine, leaving behind these eroded areas or ulcers.
It’s unclear what exactly these T cells are meant to be targeting though. Some patients have p-ANCAs in their blood, or perinuclear antineutrophilic cytoplasmic antibodies, which are a kind of antibodies that target antigens in the body’s own neutrophils.
Although not completely understood, some theories suggest this may be partly due to an immune reaction to gut bacteria that have some structural similarity to our own cells, allowing antibodies to those gut bacteria, or p-ANCAs, to “cross-react” with neutrophils.
Patients also seem to have a higher proportion of gut bacteria that produce sulfides, and often high sulfide production is correlated with periods of active inflammation as opposed to remission.
Ultimately, though, these are mostly correlations and theories, and we’ve yet to nail down the precise mechanism behind mucosal destruction; the cause is ultimately some combination of environmental stimuli, perhaps the sulfide-producing bacteria, mixed with a genetic predisposition, because patients with a family history of ulcerative colitis are more likely to develop the disease themselves.
It also seems to be more common in young women from the teens to 30s, with more prevalence among caucasians and eastern european jews.
With ulcerative colitis, the pattern for ulceration seems to be circumferential and continuous, meaning that the inflammation goes around the whole lumen and starts in the rectum and continues along the large intestine without any apparent breaks of “normal” or unaffected tissue, like it’s working it’s way from one end to the other.
As more damage is done to the tissue, patients experience pain in the left lower quadrant which corresponds to the rectum, and more severe and frequent bouts of diarrhea, sometimes with blood in the stool as well.
As the mucosa and epithelium are destroyed, blood and serum may be released into the lumen, which contributes to the blood seen in the stools, but also, what’s one of the main jobs of the large intestine?
Absorbing water. As these cells are destroyed, the large intestine can’t perform this function as efficiently and ends up letting too much water through, contributing to diarrhea.
Diagnosis of ulcerative colitis typically requires colonoscopy, which is when a long tube with a camera at the end, is inserted retrograde through the anus, and into the rectum and colon to see the ulcers, and take a biopsy.
In addition, radiological imaging maybe done with the help of CT scan, MRI, a barium enema, which is where a liquid is injected into the rectum through a small tube, and an X ray is taken to look for abnormalities in the large intestines.
Treatment for ulcerative colitis depends on the severity of symptoms, often anti-inflammatory medications like sulfasalazine or mesalamine are given; in more severe cases, drugs that suppress the immune system, like corticosteroids, azathioprine, or cyclosporine might be prescribed.
If those fail, biologic treatments, such as infliximab, a TNF inhibitor, adalimumab and golimumab can be used. Finally, if these treatment options fail, sometimes patients will have a colectomy which is a surgical removal of the colon.
Since the disease only affects the large intestine, removal of the colon generally cures the disease, but you have to weigh the benefits of curing the disease against the total loss of of the large intestine!
Alright, as a quick recap… ulcerative colitis is the most common type of inflammatory bowel disease, where ulcers form along the inner-surface or lumen of the large intestine, including both the colon and the rectum.
Ulcerative colitis is diagnosed with the help of colonoscopy, and barium enema, and treatment involves anti-inflammatory medications, immunosuppressant, or colectomy to remove diseased parts of the colon in severe cases.