Table 2. Overview of the main findings of studies of immune factors in the pathogenesis of PSC-IBD.
| Immunopathogenic factors | |||
|---|---|---|---|
| Study | Findings/associations with PSC-IBD | Weakness (−)/Strength (+) | |
| Adaptive immunity | |||
| Ponsioen et al.29 | The inflammatory infiltrate of the liver of PSC patients contains a large proportion of memory T cells | ||
| Ong et al.30 | PSC in IBD patients can develop independently from active colitis, and activity can continue after colectomy | (−) Although the results are from a meta-analysis, independent studies had small sample sizes | |
| Befeler et al.31 | PSC post-liver transplant patients have been found to still develop IBD, but with a milder course | (−) These patients were started on immunosuppressive therapy after liver transplant which could have affected the severity of IBD | |
| Kekilli et al.34 | Higher level of CD4+CD5+ T cells in patients with UC-PSC compared to patients with UC and no PSC | (−) Small sample size | |
| Innate immunity | |||
| TLR changes | Mueller et al.12 | End stage PSC livers have higher TLR protein expression and MyD88/IRAK signaling complex activation in the biliary endothelial cells, with consequent abnormal innate immune activation; In the livers of early PSC, this finding was not as evident as it was marked with low levels of pro-inflammatory markers | |
| Auto-antibodies | |||
| Anti-BEC | Xu et al.42 | Higher number of patients with PSC having anti-BEC antibodies compared to PBC, autoimmune hepatitis, and controls | (−) Control group had a significant lower number of patients |
| Ge et al.43 | No significant differences in frequency of anti-BEC among patients with PSC, AIH, HBV cirrhosis. | ||
| Roozendaal et al.44 | Anti-BEC IgG from PSC patients induced the expression of TLR4 and TLR9 in BEC which together with exposure to LPS lead to the secretion of cytokines | ||
| PR3-ANCA | Mahler et al.47 | Higher prevalence in UC vs. CD (31.1% UC vs. 1.9% CD sera) | (+) Good study power |
| Stinton et al.48 | Detected in 38.5% (94/244) of PSC patients compared to 10.6% (27/254) controls; No association with the presence or type of IBD | (+) Good study power | |
| ASCA | Muratori et al.50 | ASCA was positive in 70% (16/23) of CD patients and in 44% (11/25) of PSC patients compared to 5% of HC | (−) Small sample size |
PSC-IBD, primary sclerosing cholangitis-inflammatory bowel disease; TLR, Toll-like receptor; ASCAs, Anti-Saccharomyces cerevisiae antibodies; AIH, autoimmune hepatitis; HBV, hepatitis B virus; LPS, lipopolysaccharide; CD, Crohn’s disease; HC, healthy controls.