The Crohn’s Disease

diagram of a human digestive system

Image via Wikipedia

Hi Guys!

As the beginning of my first post-doc at the Harvard Medical School is coming closer, I decided to focus many of my future posts (although I won’t stop talking about the more important discoveries in science and their consequences in understanding reality and society) on the specific topic of my studies: the Crohn’s disease.  I will explore how molecular biology strongly improve our knowledge of this disease (and more generally of immunology), I will comment on new discoveries and their importance, I will discuss new therapies and I will provide plenty of resources to be updated on this unknown and painful disease. Whoever wants to share their pathological and human experience or the experimental discoveries will be welcome to write on the BLOG. So guys, if you want to understand Crohn’s disease do not miss to read EducereX!!!!

Introduction to Crohn’s Disease

The Crohn’s disease is chronic inflammation that may affect any part of gastro-intestinal tract (from mouth to anus). The Vienna classification (1998) classified Crohn’s disease based on the anatomical location and occurrence of complication.

With respect to anatomical location at diagnosis the classification is:

1.          ILEOCOLIC Crohn’s disease which affects both Ileum (last part of small intestine connected to the large one) and large intestine (21% of cases)

2.              Crohn’s ILEITIS which affects only the Ileum (47% of cases)

3.          Crohn’s COLITIS which affects the large intestine (28% of cases) and it is difficult to distinguish from ulcerative colitis (another idiopathic IBD).

4.          Crohn’s disease of the upper gastrointestinal tract (3%).

With respect to behavior of Crohn’s disease and occurrence of complications:

1.   stricturing: the intestine wall gets thicker and the bowel narrow until eventually completely obstruct the passageways of food: bowel obstruction (which is a main complication). This is mainly due to swollen of intestine wall (due to the inflammation) and scar tissue that reduce the bowel diameter (17%).

2. penetrating: the inflammation creates fistulae (abnormal passageways) that connect intestine to other epithelial tissues such as skin (explaining the skin rush). The frequency is 13%.

3. inflammatory: the most common pathology that causes inflammation without other complication such as stricturing and fistulae with a frequency of 70%.

The clinical symptoms can be summarize as follow:

  • Abdominal Pain
  • Diarrhea (bloody diarrhea if inflammation is at its worse)
  • Fever (in the worse case)
  • Vomiting
  • Weight loss
  • Ulcer (in some cases)

Epdemiology of Crohn’s disease.

This previously unknown disease is becoming very popular and important in the western world (with highest rate in Northern Europe, North America and UK) as is where, worldwide, the pathology is more common. The Crohn’s & Colitis American Foundation estimates that around 1.4 million of Americans suffer of Inflammatory Bowel Disease (IBD). The IBD is a terminology which groups a series of chronic inflammation of gastro-intestinal tract of which Crohn’ disease and ulcerative colitis represent the 2 more frequent conditions.

As reported by Lancet (Baumgart at al., The Lancet, 2007), in North America Crohn’s disease affects white individual with a frequency of 43.6 per 100,000 persons, a much higher frequency when compare with other ethnical group: Hispanic with 4.1 individuals per 100,000, Asian with 5.6 individuals per 100,000 and African-American people with 29.8 individuals per 100,000. These epidemiology data strongly suggest an hereditary cause of Crohn’s disease: in the next post I will comment on the genetic and other causes of the Crohn’s disease discovered so far by scientists.


About Dr Mario Perro, PhD
The path for understanding reality

3 Responses to The Crohn’s Disease

  1. Cristiano says:

    keep up with the blog Mario!! We always read your posts from here in London…interesting and challenging as ever 😉
    See you soon

  2. mzech says:

    Hi Mario,
    what would be great to add as a piece of information in this context is how pathological conditions can help in understanding basic physiological mechanisms. I find this methodologically a very powerful approach in biology. There was a nice BBC documentary recently on how the brain works. A lot of the individual functions carried out by the brain could only be mapped to a specific area when this area was injured or modified. On an immunological basis Erik Glocker and many others, including yourself, showed how important the molecule IL10 is in controlling heavy inflammatory reactions in the colon. Only when a mutation- and therefore a deviation from the normal condition- was described, could the important role played by this cytokine be confirmed (before this was the case, there were only speculations on the crucial role of IL10, further demonstarting the intimate relationship between theory and observation).
    As you are going to start your research project on Morbus Crohn, what do you expect to find out about basic physiological mechanisms happening in the gut? What has been learned so far from Morbus Crohn or Ulcerous Colitis about the gut and the immune system (this is probably a difficult question…)?

    • Well, since Morgan working on Drosophila described the mutations, all the modern biology has been based on that principle. When a new gene comes into the attention of a scientist the first thing to do is to knock it down! Molecular biology has actually allowed to genetically modify animal models in a way to specifically target precise genes. In humans that’s of course impossible and therefore scientists study the natural occurring cases of mutation in human population while trying to cure them.
      The case of Crohn’s disease it is actually different. As I will discuss next week, Crohn’s disease is a polygenic disease and that means the many different genes contribute to its pathology and often are not even the same genes. In addition it seems to be also a multifactorial disease: statistical correlation has been found for genetic and environmental (such a smoke) factors.
      The answer to your questions are actually very difficult mainly because it is difficult to say right now what I will find, if I knew it wouldn’t be a discovery! That’s the reason I will discuss this issue in several posts and by time I’ll be able to describe a more complete model. What I “hope” to describe is the importance of certain signaling pathway that control T cells activation once migrate into the gut. I will keep you updated about that.

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