The effects of belimumab on synovial inflammation and composition of
lymph nodes in SLE patients

Systemic lupus erythematosus (SLE)is an immune-mediated inflammatory disease
(IMIDs) of which the cellular and molecular alterations of the immune system
driving the diseases still remains largely unknown. Accordingly, it remains
difficult to predict the indvidual patient*s response to treatment. Moreover,
the patient*s response to treatment remains heterogeneous and difficult to
predict, despite the development of a variety of novel and powerful drugs
(including the so-called biologicals). Therefore, there is a clear need for
the identification and validation of cellular and molecular biomarkers which
can provide useful clinical information for diagnosis, classification,
prognosis and treatment, as well as the development of new therapeutic
strategies. Biomarkers can be found and analyzed in different body
compartments, of which the peripheral blood and the intra-articular synovial
fluid or tissue are most easily accessible. However, previous studies in RA and
other IMIDs showed that adaptive immune responses in other tissues such as
lymph nodes also play an important role. Investigating other immune
compartments of the body such as the lymph nodes could result in new insights.
To study the early pathogenesis of inflammatory conditions, in 2008 our
department initiated core-needle inguinal lymph node biopsy sampling. Since
then we performed more than 100 lymph node biopsy procedures. We showed that
the procedure is well-tolerated and that, other than a small hematoma which
does not require therapy in most of the cases, no complications were reported.
In the current study, we aim to investigate the effects of belimumab
(anti-BAFF) in SLE by studying the immune alterations taking place in lymph
nodes in comparison to peripheral blood and immune alterations taking place in
the endorgan, e.g. the joint (wrist, knee or ankle) by taking synovial biopsies
during a needle- or mini-arthroscopy. This procedure has been performed
frequently in our department over the last 15 years and we have ample
expertise. In this way we will be able to asses and compare immune alterations
in the lymph nodes (secondary lymphoid organ), peripheral blood (systemic) and
the joint (end organ for the disease).

This study has been transitioned to CTIS with ID 2024-518966-28-00 check the CTIS register for the current data.

The primary goal of this study is to investigate the effects of belimumab on
the composition of lymph nodes and the inflamed synovial tissue as well as
(subsets of) immune cells in the peripheral blood. In addition, we will
identify immunological alterations in lymphoid tissue and inflamed synovial
tissue of SLE patients and to correlate these alterations with disease
stage/phenotype, prognosis, and belimumab treatment response. We thereby aim to
identify and validate novel biomarkers that can be used for personalized
medicine in SLE.

The specific types of immunological alterations that we will study include:
• Genetic, epigenetic and transcriptional alterations of immune cells and
stromal cells, including single cell RNA sequencing (scRNAseq)
• TCR and BCR repertoire
• Phenotype and function of (auto-reactive) T and B cells
• Cytokine production by immune cells and stromal cells
• Signalling events in immune cells and stromal cells
• Antigen presentation by immune cells and stromal cells

All of these parameters will be compared between lymph nodes, blood and
synovium (if applicable) in SLE patients before and after belimumab treatment.

Research Hypothesis
We hypothesize that patients with SLE contain more activated immune cells in
their lymph nodes and inflamed synovial tissue. Furthermore, activation of
stromal cells such as fibroblasts and endothelial cells may also be increased
compared to (historical) healthy controls. In addition, we expect to identify
dominant T cell and B cell clones. Belimumab treatment will likely result in
reduced inflammation in the synovial tissue and perhaps even normalization of
lymph node architecture.

Patients with SLE will be recruited from the outpatient clinics of the
Amsterdam Rheumatology and immunology Center (AMC, VUmc and Reade) and referred
to the AMC for participation in this study. Any SLE patient with active disease
who will start belimumab or any other effective treatment can be included in
the study. Demographic data and clinical data regarding classification of
diagnosis, medication use and disease activity will be collected. In total 15
patients will be included starting March 2022 with an inclusion period of 2
years. Lymph node and blood samples will be obtained in all individuals. In SLE
patients with arthritis of wrist, knee or ankle joints, a needle- or
mini-arthroscopy for synovial biopsies will be performed if patients are
willing (optional).

The risk of developing a hematoma after the biopsy is approximately 3%. This
will heal spontaneously. Needle- or mini-arthroscopy gives a small (<0,3%) risk
on a hematoma, bleeding or infection.
The patient will visit our outpatient clinic several times. Total duration: 6-8
hours.