Colitis

Colitis
Amicrographdemonstratingcryptitis,amicroscopiccorrelate of colitis.H&E stain.
Specialty	Gastroenterology

Colitisis swelling orinflammationof the large intestine (colon).Colitis may beacuteand self-limited orlong-term.It broadly fits into the category ofdigestive diseases.

In a medical context, the labelcolitis(without qualification) is used if:

• The cause of the inflammation in the colon is undetermined; for example,colitismay be applied toCrohn's diseaseat a time when thediagnosisis unknown, or
• The context is clear; for example, an individual withulcerative colitisis talking about their disease with a physician who knows thediagnosis.

Signs and symptoms

Thesignsandsymptomsof colitis are quite variable and dependent on the cause of the given colitis and factors that modify its course and severity.

Common symptoms of colitis may include: mild to severeabdominal painsandtenderness(depending on the stage of the disease), persistenthemorrhagicdiarrheawith pus either present or absent in thestools,fecal incontinence,flatulence,fatigue,loss of appetiteand unexplainedweight loss.

More severe symptoms may include:shortness of breath,a fast orirregular heartbeatandfever.

Other less common or rarenon-specific symptomsthat may accompany colitis include:arthritis,mouth ulcers,painful, red and swollen skin and irritated,bloodshot eyes.

Signs seen oncolonoscopyinclude: colonic mucosalerythema(redness of the colon's inner surface),ulcerationsandhemorrhage.

Diagnosis

Symptoms suggestive of colitis are worked-up by obtaining themedical history,a physical examination and laboratory tests (CBC,electrolytes,stool culture and sensitivity, stool ova and parasites et cetera). Additional tests may include medical imaging (e.g. abdominalcomputed tomography,abdominal X-rays) and an examination with a camera inserted into the rectum (sigmoidoscopy,colonoscopy).

An important investigation in the assessment of colitis is biopsy forhistopathology.A very small piece of tissue (usually about 2mm) is removed from the bowel mucosa during endoscopy and examined under the microscope by a histopathologist. A biopsy report generally does not state the diagnosis, but should state any presence of chronic colitis, give an indication of disease activity, as well as state the presence of any epithelial damage (erosions and ulcerations).

Histopathology findings generally associated with chronic colitis include:

• 
  Crypt degeneration
• 
  Crypt branching and other architectural distortions
• 
  Paneth cell(pictured) or gastric metaplasia (only applies in the left colon and rectum)

Other findings include basal plasmacytosis and mucin depletion. Histopathology findings generally associated with active colitis include:

• 
  Neutrophilic cryptitis (neutrophils within crypt epithelium)
• 
  Crypt abscesses (luminal neutrophilic aggregates)
• 
  Gland destruction
• 
  Ulceration (seen here as absence of epithelium, and granulation tissue with many fibroblasts)

Types

There are many types of colitis. They are usually classified by the cause.

Types of colitis include:

Micrographshowingintestinal cryptbranching, ahistopathologicalfinding of chronic colitis.H&E stain.

Micrographofcollagenous colitis.H&E stain.

Micrographof acolonicpseudomembrane, as may be seen inClostridioides difficilecolitis,a type of infectious colitis.

Autoimmune

• Inflammatory bowel disease(IBD) – a group of chronic colitides.
  • Ulcerative colitis(UC) – a chronic colitis that affects the large intestine.
  • Crohn's disease(CD) – another type of IBD that often leads to colitis.

Unknown

• Microscopic colitis– a colitis diagnosed bymicroscopicexamination of colonic tissue; macroscopically ( "to the eye" ) it appears normal.
  • Lymphocytic colitis
  • Collagenous colitis

Treatment-caused

• Diversion colitis
• Chemical colitis
• Chemotherapy-induced colitis
• Radiation colitis
• Checkpoint inhibitor induced colitis

Vascular disease

• Ischemic colitis

Infectious

• Infectious colitis

A subtype of infectious colitis isClostridioides difficilecolitis,which is informally abbreviated as "C-diff colitis". It classically formspseudomembranesand is often referred to as pseudomembranous colitis, which is its (nonspecific)histomorphologicdescription.

Enterohemorrhagiccolitis may be caused byShiga toxininShigella dysenteriaeorShigatoxigenic groupofEscherichia coli(STEC), which includesserotypeO157:H7and other enterohemorrhagicE. coli.

Parasiticinfections, like those caused byEntamoeba histolytica,can also cause colitis.

Unclassifiable colitides

Indeterminate colitisis the classification for colitis that has features of bothCrohn's diseaseandulcerative colitis.Indeterminate colitis' behaviour is usually closer to ulcerative colitis than Crohn's disease.

Treatment

Treatment for this condition can include medications such as steroids and dietary changes. In some instances, hospitalization and surgery may be required.

Moreover, several studies recently have found significant relationship between colitis anddairy allergy(including: cow milk, cow milk UHT and casein),suggesting some patients may benefit from anelimination diet.

Microbiome modification

The use of oralprobioticsupplements to modify the composition and behavior of the microbiome has been considered as a possible therapy for both induction and maintenance of remission in people with Crohn's disease and ulcerative colitis. A Cochrane review in 2020 did not find clear evidence of improved remission likelihood, nor lower adverse events, in people with Crohn's disease, following probiotic treatment.

For ulcerative colitis, there is low-certainty evidence that probiotic supplements may increase the probability of clinical remission.People receiving probiotics were 73% more likely to experience disease remission and over 2x as likely to report improvement in symptoms compared to those receiving a placebo, with no clear difference in minor or serious adverse effects.Although there was no clear evidence of greater remission when probiotic supplements were compared with5‐aminosalicylic acidtreatment as amonotherapy,the likelihood of remission was 22% higher if probiotics were used in combination with 5-aminosalicylic acid therapy.Whereas in people who are already in remission, it is unclear whether probiotics help to prevent future relapse, either as a monotherapy orcombination therapy.

Research

One study reported successfully treating experimental colitis in mice withmesenchymal stem cells.

Additional research was conducted by Huanget al.that analyzed specific genes and biological markers that are associated with the risk of colon cancer development in patients with colitis. The results showed a correlation between certain biomarkers and the development of disease.

Colitis is common in parts of the world wherehelminthiccolonisation is rare, and uncommon in those areas where most people carry worms.Infectionswith helminths may alter the autoimmune response that causes the disease. Early trials ofTrichuris suisova (TSO) showed promising results when used in people with IBDbut later trials failed at Phase 2, and most were eventually discontinued.However, the phase 2 trials had used a different formulation of TSO from the one that had been used in the earlier studies that had shown positive outcomes.