Onderzoek naar de samenstelling van afweercellen in Psoriasis Artritis en Psoriasis.

Rationale:
Patients with psoriatic arthritis (PsA) suffer from both chronic joint and skin inflammation, resulting in a greatly reduced quality of life. Approximately 30% of patients with psoriasis will develop arthritis. However, sometimes skin signs precede arthritis and vice versa, arthritis may precede skin lesions for many years[1]. Till today one cannot predict which patient with psoriasis will develop arthritis or not, since predictive tests are not available. It is known that the immune system and especially T cells play a major role in the pathogenesis of both arthritis and of psoriasis[2]. However the exact phenotype and functional role of T cells that mediate inflammation in the skin and in the joints remain unclear[3] [4, 5]. Treatment of PsA consists of DMARDs (disease-modifying antirheumatic drugs) that in some cases aren¡¯t effective or whish the patient can not tolerate. In such cases treatment with biologicals is indicated [6].


Objective:
To investigate whether the T cell receptor profile of T cells from psoriasis skin lesions and from inflamed joints in psoriatic arthritis are identical or not, in order to be able to predict whether a certain patient will develop arthritis or not.

Secondary objective: To investigate whether the pathogenic T-cells in inflamed joints of PsA patients are effectively reduced after standard anti-arthritic therapies.
Our hypothesis is that pathogenic T cells in the skin and/or the joints of PsA patients express a different T cell receptor profile compared to T cells from plaque-type psoriasis without arthritis.


Study design:
A comparative study, whereby T cells isolated from PsA joints and psoriasis lesions will be analysed and compared with the T cell receptor profile of T cells from psoriasis skin lesions of patients without arthritis.


Study population:
Patients (18-75 years of age) with psoriatic arthritis who have an inflamed knee-joint, and patients (18-75 .years of age) with only psoriasis, requiring systemic treatment in accordance with prevailing Dutch guidelines will be included. Furthermore T cells isolated from breast and abdominal skin samples after plastic surgery will serve as a reference. In total 60 patients will be included; 20 psoriatic arthritis patients, 20 psoriasis patients and 20 patients that donate their breast/abdomen tissue after breast or paunch reduction (waste material).


Intervention:

From the PA patients and the psoriasis patients 40ml heparinised peripheral blood, non-involved, and involved psoriatic skin biopsies will be taken. From the PsA patients with knee joint inflammation, synovial biopsies and synovial fluid from the involved knee will be collected.
After sampling biopsy materials, patients with active psoriatic arthritis will receive treatment according to current standard guidelines[6].
From above mentioned samples DNA is isolated and for each sample a PCR for TCRG is performed to identify the gamma chain profile. Each tissue biopsy represents a random sample of T cells. When (oligo) clonal expansion of T cells happens in psoriatic arthitis, we will identify these T cells in our assays. Mononuclear blood cells contain a wide variety of T cells and we will use blood as the patient¡¯s negative control, resulting in a Gaussian distribution of peaks in our assay. As a positive control we will use a DNA from an in vitro cultured T cell clone containing one TCRG resulting in one peak in the GeneScan. The department of Immunology has great expertise in extracting DNA from skin biopsies for the diagnostic purposes. For the diagnosis of cutaneous T cell lymphoma, TCR PCR is a routine and indispensable procedure [7].


Main study parameters/endpoints:
Typing of pathogenic T cell population in skin an joints:

1. T-cell receptor (TCR-G) profile;

2. Gene expression profile;

3. Effects of anti-arthritic therapy on pathogenic T cells.


Benefit and risks associated with participation:
The results of this study could help other patients to be diagnosed in an early stage, to discriminate whether they are affected with psoriasis or psoriatic arthritis. So appropriate therapy can be given before lesions become disabling.
The benefit for the patient could be an improvement or prevention of the psoriasis plaques and further joint inflammation by early treatment.
Patients will not experience higher risks when treated for PsA or psoriasis in this study, because the treatment they receive is according to current standards guidelines.
Synovial biopsies are routinely taken as a diagnostic procedure [8, 9]. Also for research purposes synovial biopsies are taken in the MEC-approved REACH study of the department of rheumatology of the Erasmus MC. Risks or complications that can occur after taking biopsies from knee or skin are possible bacterial infections, a bleeding at the location where the biopsy is taken or technical problems with the biopsy tool. There are no studies that show how big these risks are after a knee biopsy, but as a reference: an experienced rheumatologist knows that every year 1500 synovial biopsies are taken in the Netherlands and complications are rarely seen.

Pathogenic T cells in the skin and/or the joints of PsA patients express a different T cell receptor profile compared to T cells from plaque-type psoriasis without arthritis.

3 years.

This is a comparative study where we investigate the differences in the T-cel receptor profile in PsA patients and psoriasis patients and we study the effects of standard therapy on pathogenic T-cells in PsA. The investigator or qualified designee will explain the study to the subject, answer all of her/his questions, and obtain written informed consent before performing any study-related procedures. A copy of the signed informed consent will be given to the subject.

Consecutive patients will be screened, including demographics (age, sex, race and height), medical history including previous/concomitant medication, and the disease characteristics by PASI.

There will be a physical examination, routine laboratory including Hepatitis B and C, urinary sediment. A chest X-ray and tuberlin skin test will be tested to exclude tuberculosis. In HIV high risk patients we will do a HIV-test.
Women will perform a pregnancy test to exclude pregnancy.
If all the test results fulfil our inclusion criteria, skin-, synovia biopsies and blood will be taken.

The human material will be transported to the laboratory.

Human research material:
Biopsies will be taken from the different patient groups;
From each patient of the PsA group 40ml heparinised peripheral blood, two 4mm biopsies of non-involved buttock skin and 2 biopsies of 4 mm of the involved psoriatic skin, and 20 biopsies of 2 mm of the involved synovial tissue and a synovial fluid punction (in case of swelling of the joint) will be taken.

From each patient of the psoriasis group 40ml heparinised peripheral blood, two 4mm biopsies of non-involved psoriatic skin and 2 biopsies of 4 mm of the involved psoriatic skin will be taken.

From each patient of the control group 40ml heparinised peripheral blood and 2 biopsies of the waste skin will be taken.

Laboratory techniques that are used to answer our hypothesis:

1. Gene scan technique will be used to determine the difference in T-cell receptor
(TCR-G) profile between psoriatic skin and inflamed knee joint in PsA patients;

2. Gene scan technique will be used to determine the difference in T-cell receptor
(TCR-G) profile between psoriatic skin in psoriasis patients and psoriatic skin in PsA
patients;

3. Micro-array technique will be used to determine the difference in gene expression profile of the T-cells in psoriatic skin of psoriasis patients and of PsA patients;

4. Micro-array technique will be used to determine the gene expression of
the T-cells in inflamed knee joint of PsA patients;

5. Gene scan will be used to determine the effects of therapy on pathogenic T-cells of psoriasis and PsA.


After the biopsies are taken the patients of PsA group and the psoriasis group will be treated in accordance with prevailing Dutch guidelines, either with MTX or an anti-TNF biological. After a period of 6 weeks for the arthritis joint a new biopsy will be taken in order to monitor the effect of treatment on the T cells.

In order to monitor the effect of treatment on the T cells in the skin, skin biopsies will be taken when a 50% reduction in the PASI score is reached. These biopsies will be analysed in the laboratory and will be compared to the biopsies that where taken before treatment.