What causes psoriatic arthritis?
Psoriatic arthritis (PsA) is an autoimmune condition where your immune system mistakenly attacks healthy joints and tissues, causing inflammation and damage. The exact cause isn't fully understood, but researchers believe it develops from a combination of factors.
Genetic Factors
Certain Show Full Answer
What causes psoriatic arthritis?
Psoriatic arthritis (PsA) is an autoimmune condition where your immune system mistakenly attacks healthy joints and tissues, causing inflammation and damage. The exact cause isn't fully understood, but researchers believe it develops from a combination of factors.
Genetic Factors
Certain gene mutations make some people more likely to develop PsA:
- HLA-B27, HLA-B8, and HLA-B38 genes are more common in people with PsA than those with only psoriasis
- HLA-C06 gene is linked more closely to psoriasis alone
- People with this gene who develop PsA often get it later in life
- About 40% of people with PsA have a family member with psoriasis or arthritis
Immune System Involvement
T cells, a type of immune cell, play a major role in PsA. These cells release proteins called cytokines that act as messengers. In people prone to PsA, T cells release more inflammatory cytokines, leading to joint pain, swelling, and damage.
Environmental Triggers
Certain environmental factors may trigger PsA in people who are genetically predisposed:
- Infections like strep throat (Streptococcus pyogenes)
- Physical injuries
- Viruses
These situations can set off an immune response that leads to PsA development.
Gut Health Connection
Emerging research suggests gut dysbiosis (an imbalance of gut bacteria) may contribute to PsA. People with PsA have been found to have lower levels of gut bacteria and less diverse gut microbiomes compared to those without the condition.
November 10, 2025
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