Inflammatory Bowel Disease Flashcards
2 MAJOR FORMS OF IBD:
Ulcerative colitis (UC) Crohn’s disease (CD)
risk factors for IBD? (11)
- SMOKING
- DIET
- MICROBIOME
- Medication
- Sleep
- Stress
- Physical activity
- Air pollution
- UV exposure/vitamin D
- Appendectomy
- Heavy metal
How does IBD begin?
with an infection
Summarise IBD into 4 stages:
1) complex interplay between host and microbes
2) disrupted innate immunity and impaired tolerance
3) pro inflammatory compensatory mechanisms
4) physical damage and chronic inflammation
Gut layer affected by CD
all
Gut layer affected by UC
mucosa/submucosa
Regions affected by UC
Rectum, spreads proximally
Regions affected by CD
any part of GI
Cure success of surgery CD?
Not always curative
Cure success of surgery UC?
Curative
Pattern of inflammation, UC?
Continuous
Pattern of inflammation, CD?
Patchy
CD rarity of abscesses/fissures/fistulae?
Common
UC rarity of abscesses/fissures/fistulae?
Not common
Which IBD has IFN’s involved?
CD, gamma and alpha
Which IBD is TH1 mediated
CD
Which IBD is TH2 mediated
UC
IL in CD?
17 and 23
IL in UC?
5 and 13
T cell expansion and apoptosis in CD?
Florid expansion, defective apoptosis
T cell expansion and apoptosis in UC?
Limited clonal expansion, normal T cell apoptosis
Systemic clinical features of IBD?
Anaemia, fevers, sweats, jaundice Abdominal pain Arthritis Weight loss Skin rash Diarrhoea
Supportive therapies for IBD?
Fluids, blood, nutritional support
Symptom therapies for IBD: active disease?
Glucocorticoids, aminosalicylates and immunosuppressives
Symptom therapies for IBD: preventing remission?
Glucocorticoids, aminosalicylates and immunosuppressives
Curative therapies IBD? (2)
Microbiome manipulation, biologic therapies (anti TNFalpha antibodies)
Aminosalicylate examples?
Mesalazine or olsalazine
MoA of aminosalicylates? (3)
- Regulation of NF-B/MAPK- downregulates pro-inflammatory cytokines
- Regulation of COX-2- downregulates prostaglandin production
- (smaller way) they can scavenge oxidants
Relationship between Mesalazine and olsalazine
Olsalazine has to be activated by gut flora in the colon and split into the two mesalazine molecules
How can aminosalcylates be targeted at the colon
Olsalazine has to be activated by gut flora in the colon
What are aminosalicylates such as mesalazine AKA?
5-aminosalicylic acid
First line treatment for UC?
Aminosalicylates
Effectiveness of Aminosalicylates in UC?
- First line in inducing and maintaining remission
- Good evidence base
Effectiveness of Aminosalicylates in CD?
- Ineffective in inducing remission
First line treatment for CD?
Glucocorticoids
Examples of glucocorticoids?
Prednisolone, Fluticasone, budesonide
Effect of glucocorticoids?
- Powerful anti-inflammatory and immunosuppressive drugs
what are glucocorticoids Derived from
cortisol
Main culprit in IBD? (the cell)
dendritic cells
Difference in treatment for CD and UC?
First line is aminosalicylates in UC and glucocorticoids in CD
Prednisolone vs budesonide?
Prednisolone for CD causes more side effects than budesonide but prednisolone is better at inducing remission in active CD
First treatment for mild CD?
- Budesonide
What is budesonide used for?
Mild CD
STRATEGIES FOR MINIMISING UNWANTED EFFECTS OF GCs: (3)
- Administer topically - fluid or foam enemas or suppositories
- Use a low dose in combination with another drug
- Use an oral or topically administered drug with high hepatic first pass metabolism e.g. Budesonide so little escapes into the systemic circulation
What does azathioprine do?
An immunosuppressive
Purine antagonist
Interferes with DNA synthesis and cell replication
What type of nuceleotide does azathioprine interfere with
Purines
What is the active form of azathioprine
6-mercaptopurine
What is the prodrug of 6-mercaptopurine
Azathioprine
2 ways 6-mercaptopurine interferes with DNA synthesis?
One active form of the drug inhibits de novo purine synthesis and the other gets incorporated into DNA
Where/how is 6-mercaptopurine cleaved from Azathioprine
By gut flora in the gut
Where does 6-mercaptopurine impair immune responses? (4)
- cell- and antibody-mediated immune responses
- lymphocyte proliferation
- mononuclear cell infiltration
- synthesis of antibodies
What does 6-mercaptopurine enhance re. immune responses? (4)
- T-cell apoptosis
Azathioprine success in UC and CD?
- Some success in inducing remission in Ulcerative Colitis
- No benefit in CD active disease
- Mainly used to maintain remission in CD
Time for azathioprine to become useful in Crohns disease?
3 to 4 months treatment for clinical benefit
What is azathioprine useful for re. CD?
It is effective in maintaining remission of CD
Unwanted side effects of azathioprine? (5)
- Nearly 10% patients have to stop treatment because of the serious side effects
- Pancreatitis
- Bone marrow suppression
- Hepatotoxicity
- Increased risk (~ 4 fold) of lymphoma and skin cancer
How to deliver drugs more efficiently for IBD? (4)
1) Enteric coating ensures degradation in the colon as it resists degradation in acidic pH of stomach
2) Time dependent, self destructive polymer packaging
3) Pressure/osmotic controlled packaging that relies on the more aqueous environment of the colon, which allows water in and pushes drug out
4) Even more complex polymers combine time and pH factors as time can mean premature drug release if the digestion is slow, and pH factors can mean the drug is released prematurely in the small intestine rather than the colon
Anti-TNFalpha drug?
Infliximab
How can you manipulate the microbiome? (3)
- Nutrition-based therapies
- Faecal microbiota replacement (FMT) therapies
- Antibiotic Treatment - Rifaximin
Success of probiotics in CD?
No evidence
Success of probiotics in UC?
Is evidence for it
Probiotics vs 5-ASA in UC
both equally effective
Success rate of faecal microbiota therapies?
Not enough evidence
how does rifaximin work?
Interferes with bacterial transcription by binding to RNA polymerase
Successfulness of rifaximin in CD?
Induces and sustains remission
Topical steroids vs 5-ASA in inducing UC remission?
topical 5-asa is more successful
Successfulness of rifaximin in UC?
May be beneficial in UC
What are biologic therapies in IBD?
Anti-TNFalpha antibodies
Example of anti-TNFalpha antibody/biologic therapy?
Infliximab
MoA of anti-TNFalpha Ab? (5)
- Anti-TNF reduces activation of TNF receptors in the gut
- Reduces downstream inflammatory events
- Also binds to membrane associated TNF
- Induces cytolysis of cells expressing TNF
- Promotes apoptosis of activated T cells
Route of admin of infliximab?
IV
Half life of infliximab?
9.5 days
Repeat infusion frequency?
Every 8 weeks
Which IBD is ANTI-TNF therapy useful for
CD
Success of ANTI-TNFalpha in CD?
Success
Success of ANTI-TNFalpha in UC?
unsuccessful
Why isANTI-TNFalpha much more useful in CD than UC?
Crohns is TH1 driven, UC is TH2, TH2 has TNF α much less involved
Adverse effects of anti-TNFalpha therapy (7)
- 4x - 5x increase in incidence of tuberculosis
- Also risk of reactivating dormant TB
- Increased risk of septicaemia
- Worsening of heart failure
- Increased risk of demyelinating disease
- Increased risk of malignancy
- Can be immunogenic – azothiaprine reduces risk, but raises TB/maligancy risk
Combining infliximab with what improves its effectiveness?
Azathioprine
New targets for IBD? (4)
- Integrin (needed for cells to migrate)
- Interleukins (IL12; IL17; IL23)
- Interleukin receptors
- Janus kinase (JAK) cytoplasmic cell signalling