Ulcerative Colitis

What is Ulcerative Colitis? Ulcerative colitis (UC) is a type of chronic inflammatory bowel disease (IBD) that results in severe digestive symptoms. UC affects men and women equally, and while the first symptoms can occur at any age, there is a bimodal pattern in the age of onset. The first and main peak is between 15 to 30 years of age, and the second peak is seen between 60 to 70 years of age. Like Crohn’s disease (CD), UC has historically been more prevalent in urban areas, but the incidence has been stabilizing in western countries and increasing in developing countries that are experiencing greater westernization and urbanization.

What are the causes of Ulcerative colitis?

The pathophysiology of UC is thought to be the consequence of the interaction of multifactorial contributors.

  • Genetics- First-degree relatives of those diagnosed with UC are 4 times more likely of developing UC and those of Ashkenazi Jew heritage have a 3-5 times higher risk of being diagnosed with UC. However, many diagnosed with UC have no family history, which indicates that other factors have a significant influence on the development of the disease. The genes involved in Ulcerative colitis, like in CD, are thought to follow a polygenic inheritance pattern, and both diseases seem to share 137 loci with common polymorphisms.
  • Alterations to the microbiome– Disturbances in the gut microbiota have been found in patients diagnosed with UC. This includes increased proportions of Enterobacteria and lower bacterial diversity, such as lower levels of Firmicutes and Bacteroides. A few factors implicated in the alteration of the microbiota include diet, extremes in hygiene, and early introduction to antibiotics.
  • Immune dysfunction– Abnormalities in the immune response starting with impaired mucin synthesis and secretion to decreased downregulation of inflammation stemming from a diminished expression of PPAR-γ are implicated in the disease’s development. As there is a decrease in the initial immune response with the lack of mucin and an unregulated inflammatory response, there is damage to the epithelial tissue and subsequent activation of the innate and adaptive immune response.
  • Environmental factors– Several environmental factors are implicated in the development of UC, such as a westernized diet with reduced fiber and increased fat consumption, and urbanization of the environment. However, several factors have also been shown to have a protective influence:
    • Cigarette smoking
    • Appendectomy
    • Adequate dietary fiber
    • Breastfeeding
    • Childhood exposure to diverse levels of hygiene, such as living near farm animals, access to hot water, bed-sharing, and having pets.

Signs and symptoms of Ulcerative colitis

While UC shares some symptoms with Crohn’s disease, such as diarrhea, cramping, blood in stool, and weight loss, the extent of these symptoms varies with each disease and severity. Bloody diarrhea is more commonly seen in UC, while weight loss tends to only be seen in very severe disease. The severity of the disease is measured using the Montreal classification of severity that rates from mild, moderate, to severe based on several factors including stool frequency, severity of diarrhea, systemic symptoms, and lab abnormalities.

Other characteristics of UC include:

  • Colitis characterized by urgency and small and frequent bowel movements, abdominal colic, tenesmus, and incontinence.
  • Extraintestinal manifestations including uveitis, ankylosing spondylitis, and primary sclerosing cholangitis.
  • Increased risk of colon cancer.

Source: Du, L., & Ha, C. (2020). Epidemiology and Pathogenesis of Ulcerative Colitis. Gastroenterology Clinics of North America, 49(4), 643–654. https://doi.org/10.1016/j.gtc.2020.07.005