HLA-DPA1*02:01~B1*01:01 is a risk haplotype for primary sclerosing cholangitis mediating activation of NKp44+ NK cells

OBJECTIVE

Primary sclerosing cholangitis (PSC) is characterised by bile duct strictures and progressive liver disease, eventually requiring liver transplantation. Although the pathogenesis of PSC remains incompletely understood, strong associations with HLA-class II haplotypes have been described. As specific HLA-DP molecules can bind the activating NK-cell receptor NKp44, we investigated the role of HLA-DP/NKp44-interactions in PSC.

DESIGN

Liver tissue, intrahepatic and peripheral blood lymphocytes of individuals with PSC and control individuals were characterised using flow cytometry, immunohistochemical and immunofluorescence analyses. HLA-DPA1 and HLA-DPB1 imputation and association analyses were performed in 3408 individuals with PSC and 34 213 controls. NK cell activation on NKp44/HLA-DP interactions was assessed in vitro using plate-bound HLA-DP molecules and HLA-DPB wildtype versus knock-out human cholangiocyte organoids.

RESULTS

NKp44+NK cells were enriched in livers, and intrahepatic bile ducts of individuals with PSC showed higher expression of HLA-DP. HLA-DP haplotype analysis revealed a highly elevated PSC risk for HLA-DPA1*02:01~B1*01:01 (OR 1.99, p=6.7×10-50). Primary NKp44+NK cells exhibited significantly higher degranulation in response to plate-bound HLA-DPA1*02:01-DPB1*01:01 compared with control HLA-DP molecules, which were inhibited by anti-NKp44-blocking. Human cholangiocyte organoids expressing HLA-DPA1*02:01-DPB1*01:01 after IFN-γ-exposure demonstrated significantly increased binding to NKp44-Fc constructs compared with unstimulated controls. Importantly, HLA-DPA1*02:01-DPB1*01:01-expressing organoids increased degranulation of NKp44+NK cells compared with HLA-DPB1-KO organoids.

CONCLUSION

Our studies identify a novel PSC risk haplotype HLA-DP A1*02:01~DPB1*01:01 and provide clinical and functional data implicating NKp44+NK cells that recognise HLA-DPA1*02:01-DPB1*01:01 expressed on cholangiocytes in PSC pathogenesis.

Biliary strictures: endoscopic assessment and management

The diagnosis of biliary strictures can be challenging. Endoscopy has an established role in the diagnosis and therapy of biliary strictures. However, the diagnostic yield from conventional endoscopic retrograde cholangiopancreatography tissue sampling is modest. Improvements in existing technologies as well as the implementation of novel technologies and techniques have the potential to improve the diagnostic performance of endoscopy and expand its therapeutic role. Recent studies have enabled greater clarity about the role of preoperative biliary drainage and the choice of stents in this setting as well as the utility of metal stents in benign and malignant disease.

Primary biliary cholangitis: new treatments for an old disease

Primary biliary cholangitis (PBC) is an immunological condition that causes a significant health disturbance and dramatically reduces the quality of life for those affected with the disease. It is a potentially fatal disease that can lead to multiple hepatic and extrahepatic complications. Having adequate therapeutic interventions that can improve the course of the disease is imperative in reducing the associated morbidity and mortality. Ursodeoxycholic acid (UDCA) is the gold standard therapy. However, it has been associated with suboptimal response rates in a significant proportion of patients. Despite UDCA, approximately 35%-40% of individuals with PBC still experience a progression of the disease, leading to liver failure and requiring liver transplantation. Recent studies of new pharmacological approaches have shown beneficial outcomes. Some of these agents can now be applied to a clinical scenario. In this review article, we will outline the new and emerging treatments for PBC.

Autoimmune liver disease: evaluating overlapping and cross-over presentations-a case-based discussion

The three classic autoimmune liver diseases are recognised based on identifying varying clinical, laboratory, histological and radiological features that collectively classify patients. In the absence of defined aetiological factors, it is recognised that disease spectrum is broad, and, in this context, it is not infrequent for disease boundaries to be blurred, leading to overlapping features that may be present at the time of diagnosis or may appear later in the course of disease. Given the absence of accepted diagnostic criteria for overlap/cross-over syndromes, alongside weak data for intervention, it is recommended that a multidisciplinary, patient-specific approach be used to establish individual treatment pathways.

Treatment of relapsing autoimmune pancreatitis with immunomodulators and rituximab: the Mayo Clinic experience

BACKGROUND

There is a paucity of data on long-term management of type 1 autoimmune pancreatitis (AIP), a relapsing steroid-responsive disorder.

OBJECTIVE

We describe our experience with treatment of relapses and maintenance of remission using steroid-sparing immunomodulators (IMs) and induction of remission using rituximab (RTX).

METHODS

We obtained details of disease relapse and treatment in 116 type 1 AIP patients from clinic visits, medical records and telephone interviews. We compared relapse free survival in those treated with IMs versus those treated with steroids alone, assessed patients' response to RTX, and identified treatment-related complications.

RESULTS

During a median follow-up of 47 months, 52/116 AIP patients experienced 76 relapse episodes. The first relapse was treated with another course of steroids in 24 patients, and with steroids plus IM in another 27 patients; subsequent relapse-free survival until a second relapse was similar in the two groups (p=0.23). 38 patients received an IM for >2 months; failure or intolerance of IM therapy occurred in 17 (45%). 12 patients with steroid or IM intolerance/resistance were treated with RTX, an antiCD20 antibody; 10 (83%) experienced complete remission and had no relapses while on maintenance therapy. Treatment-limiting side effects related to RTX were uncommon.

CONCLUSIONS

In type 1 AIP relapses are common. Relapse-free survival is similar in those treated with steroids plus IM compared to those treated with steroids alone. Nearly half the patients on IMs will relapse during treatment. RTX is effective in the treatment of both IM resistant and steroid intolerant patients.