Ankylosing Spondylitis
Definition
- Ankylosing Spondylitis (AS) = an inflammatory disease that, over
time, can cause some of the small bones in the spine (vertebrae) to
fuse
- Also called Bechterew’s disease
- It’s part of Seronegative Spondyloarthropathies (= a group of
autoimmune diseases that affect the joints) and this includes these
other diseases:
o Psoriatic Arthritis: inflammation of the peripheral joints,
tendons or fingers
o Reactive arthritis: inflammation in mainly the knees, feet,
toes, hips and ankles and it usually develops after having an
infection, such as a gastro-enteritis or an STD such as
Chlamydia
o IBD-associated arthritis: people with IBD (inflammatory
bowel disease) can also get arthritis
Epidemiology
- AS affects more men than women
- Symptoms typically begin in early adulthood
1
@MyMedicalPulse
, - More common in white people than African Americans
- Approximately 0,2-0,5% of the US population has AS
Causes and risk factors
AS has so specific cause, however genetic factors seem to be involved:
- People with the HLA-B27 gene are at a greatly increased risk of
developing AS
o HLA-B27 encodes for an MHC class I molecule
- However, not everyone with this gene develops the condition
Pathophysiology:
1) A CD8+ T-cell (Tc-cell) uses its TCR (T cell receptor) to bind to the
antigen presented by the MHC
2) Inflammation process starts by T-cells secreting cytokines to recruit
macrophages and neutrophils
3) The neutrophils will release cytokines, such as TNF-alfa (tumor
necrosis factor) and IL1 (interleukin) which worsen the
inflammation
4) Over time, the inflammation destroys the intervertebral joints, facet
joints and sacroiliac joints
5) Fibroblasts replace the destroyed joint with fibrin —> layers of
fibrin form a tough fibrous band around the joints, which limits the
range of motion
6) Eventually osteoblasts are activated and ossification will start
a. Ossification is the process of turning fibrous tissue into bone
Risk factors include:
2
@MyMedicalPulse
Definition
- Ankylosing Spondylitis (AS) = an inflammatory disease that, over
time, can cause some of the small bones in the spine (vertebrae) to
fuse
- Also called Bechterew’s disease
- It’s part of Seronegative Spondyloarthropathies (= a group of
autoimmune diseases that affect the joints) and this includes these
other diseases:
o Psoriatic Arthritis: inflammation of the peripheral joints,
tendons or fingers
o Reactive arthritis: inflammation in mainly the knees, feet,
toes, hips and ankles and it usually develops after having an
infection, such as a gastro-enteritis or an STD such as
Chlamydia
o IBD-associated arthritis: people with IBD (inflammatory
bowel disease) can also get arthritis
Epidemiology
- AS affects more men than women
- Symptoms typically begin in early adulthood
1
@MyMedicalPulse
, - More common in white people than African Americans
- Approximately 0,2-0,5% of the US population has AS
Causes and risk factors
AS has so specific cause, however genetic factors seem to be involved:
- People with the HLA-B27 gene are at a greatly increased risk of
developing AS
o HLA-B27 encodes for an MHC class I molecule
- However, not everyone with this gene develops the condition
Pathophysiology:
1) A CD8+ T-cell (Tc-cell) uses its TCR (T cell receptor) to bind to the
antigen presented by the MHC
2) Inflammation process starts by T-cells secreting cytokines to recruit
macrophages and neutrophils
3) The neutrophils will release cytokines, such as TNF-alfa (tumor
necrosis factor) and IL1 (interleukin) which worsen the
inflammation
4) Over time, the inflammation destroys the intervertebral joints, facet
joints and sacroiliac joints
5) Fibroblasts replace the destroyed joint with fibrin —> layers of
fibrin form a tough fibrous band around the joints, which limits the
range of motion
6) Eventually osteoblasts are activated and ossification will start
a. Ossification is the process of turning fibrous tissue into bone
Risk factors include:
2
@MyMedicalPulse
