Jan van Laar

Perigranuloma localization and abnormal maturation of B cells: emerging key players in sarcoidosis?

RATIONALEnRecent observations of abnormal immunoglobulin responses and case reports describing successful B-cell ablative therapy suggest involvement of B cells in the pathogenesis of sarcoidosis.nnnOBJECTIVESnTo investigate how abnormal B-cell maturation and function in patients with sarcoidosis contribute to disease.nnnMETHODSnPatients with sarcoidosis (n = 32) were included for detailed analysis by immunohistochemistry of tissue, flow cytometry of blood B-cell subsets, and serum immunoglobulin levels. Vaccination responses in patients with sarcoidosis to influenza virus and encapsulated bacteria and molecular analysis of immunoglobulin heavy chain transcripts were studied for functional analysis of immunoglobulin responses.nnnMEASUREMENTS AND MAIN RESULTSnPerigranuloma localization of IgA-producing plasma cells and numerous B cells were found in affected tissues. Total blood B-cell numbers were normal, CD27(+) memory B cells were significantly reduced, and CD27(-)IgA(+) B cells were significantly increased; the results are normalized in patients treated with TNF-α blockers. Despite this, patients had normal serum immunoglobulin levels and normal antigen-specific immunoglobulin responses. IgA and IgG transcripts, however, showed high frequencies of somatic hypermutations and increased usage of downstream IgG subclasses, suggestive for prolonged or repetitive responses.nnnCONCLUSIONSnThe large B-cell infiltrates in granulomatous tissue and increased molecular signs of antibody maturation are indicative of direct involvement of B cells in local inflammatory processes in patients with sarcoidosis. Moreover, CD27(-)IgA(+) B cells could be a marker for treatment with TNF-α blockers. These findings of B cells as emerging key players provide a rationale for a systematic study on B-cell ablative therapy in patients with sarcoidosis.

Low prevalence of NOD2 SNPs in Behçet's disease suggests protective association in Caucasians

OBJECTIVEnIt has been shown previously that three nucleotide-binding oligomerization domain containing 2 (NOD2) variants (Arg702Trp, Gly908Arg and Lue1007fs) are associated with Crohns disease (CD), a disorder clinically resembling Behçets disease (BD). We studied the frequency of these variants in BD patients.nnnMETHODSnDNA samples of 200 BD patients [59 Caucasians, 139 Middle Easterns (MEs) of Arab descent and 2 Asians] and 520 healthy controls (444 Caucasians and 76 MEs) were genotyped using a Taqman assay.nnnRESULTSnBoth the Arg702Trp and Leu1007fs (frameshift) variants were significantly less frequently present among BD patients compared with healthy controls (0.5 vs 5.8%; P < 1.10(-5) and 0.0 vs 1.8%; P < 0.007, respectively). In the Caucasian subpopulation, Arg702Trp was significantly less frequent in the BD group as compared with the controls (P = 0.04); whereas in the ME subpopulation, a trend was observed (P < 0.06).nnnCONCLUSIONSnOf the three CD-associated single nucleotide polymorphisms, one of the variant NOD2 alleles, was found to be present significantly less in Caucasian BD patients.

Immunopathogenesis of granulomas in chronic autoinflammatory diseases

Granulomas are clusters of immune cells. These structures can be formed in reaction to infection and display signs of necrosis, such as in tuberculosis. Alternatively, in several immune disorders, such as sarcoidosis, Crohns disease and common variable immunodeficiency, non‐caseating granulomas are formed without an obvious infectious trigger. Despite advances in our understanding of the human immune system, the pathogenesis underlying these non‐caseating granulomas in chronic inflammatory diseases is still poorly understood. Here, we review the current knowledge about the immunopathogenesis of granulomas, and we discuss how the involved immune cells can be targeted with novel therapeutics.

Somatostatin receptor scintigraphy patterns in patients with sarcoidosis

Purpose Sarcoidosis is a multisystem granulomatous disorder, most frequently involving the lungs, skin, or eyes. Somatostatin receptor scintigraphy (SRS) can visualize sarcoid granulomas through binding of a radionuclide-coupled somatostatin analog to somatostatin receptors that are expressed in sarcoidosis. Uptake and patterns on SRS were studied and correlated to clinical and conventional findings. Patients and Methods Data of 218 SRSs undertaken for the analysis of potential sarcoidosis were studied. These scintigraphies were retrospectively studied on intensity uptake degrees and localization of sarcoidosis-associated lesions, and compared with conventional radiological techniques (chest x-ray and CT). Results In all but 1 of the 175 evaluable patients, SRS demonstrated uptake. In patients with thoracic sarcoidosis-associated lesions, SRS improved the yield of visualization of chest x-ray in 20 (36%) and CT in 7 (32%) of histologically unproven patients, and in 31 (30%) and 8 (14%) of the histologically proven patients, respectively. Mediastinal lesions together with either eye, salivary glands, clavicular, or hilar localizations were most frequent demonstrated on SRS and constituted characteristic patterns. Exclusive extrapulmonary disease was found in 6% of the patients. Conclusions Somatostatin receptor scintigraphy enhances the yield of investigations in sarcoidosis patients and therefore provides a useful and sensitive imaging technique to monitor organ involvement and therapeutic efficacy in patients with sarcoidosis.

Can epidemiological studies uncover the origin of Behçet’s disease?

Whenever prevalence figures of Behçet’s disease (BD) are discussed, the geographical roots of this multisystem auto-inflammatory disorder come to mind. It has been hypothesized that BD originated somewhere in the Turkish region, and there are various indications that may support this. One of the most eye-catching is the name-giver, Hulusi Behçet, a Turkish dermatologist who described patients with a trio of symptoms [consisting of aphthous stomatitis, genital ulcers and recurring (hypopyon) uveitis] back in 1937 [1]. However, we believe that reports of patients with symptoms of BD date back to the 5th century BC: in his third book of endemic diseases (from the beginning of the Classical period of the Ancient Greek Empire), Hippocrates described a local epidemic occurrence of such patients [2]. During that century, travelling and ethnic interaction was facilitated by the development of trading routes within the Orient. The building of roads such as the Royal Road of the Persian Empire was followed by the expansion of the Greek Empire of Alexander the Great into Central Asia. BD may have subsequently spread eastwards. We see this possibility supported by various demographic studies indicating the prevalence as being highest in Turkey, then descending in magnitude through the Middle East, and Central and Eastern Asia to Japan [3]. The Silk Road disease theory conceived by Shigeaki Ohno, one of the pioneers of BD research, describes the possible dispersion of BD via these trading routes [4]. In modern times, the epidemiology is reversed towards the West, reflected in a low occurrence in Western countries [3, 5]. Epidemiological studies are frequently cited and used to establish the true rarity of a disease, or to highlight geographical data that might be linked to potential environmental or genetic causes. However, reported prevalence varies not only between countries, but also between study designs. The meta-analytical approach by Maldini et al. (published in this issue) endeavours to put an end to the incommensurability of each reported prevalence and calls for standardization of epidemiological study designs. The study reproted by Maldini et al. found the highest prevalence of BD to be in the Turkish population (almost 120/ 100 000, a figure that was not equalled by any of the other cohorts analysed) [6]. However, 120/100 000 is lower than some individual studied, whereas the pooled data reached 10.3/100 000 inhabitants—a figure not often observed in the West or in countries below the equator. The predominance of reports from Middle Eastern countries in the meta-analysis by Maldini in this paper (without corrections for ancestry) might explain the latter. Corrections were made for clinical and methodological confounding factors via sensitive and robust methods of recognizing the source of the heterogeneity, analysing for sufficient weight and evaluating the degree to which each single study affected the overall figures. The most important aspect was to recognize the risk of undercounting in studies based on, for example, hospital registers (the census method) as compared with studies using a sample survey. The latter method collects cases directly from a community and produces a higher prevalence. Maldini et al. indeed demonstrated the highest prevalence numbers (82.5/100 000) in cohorts using sample surveys. It is important to note that this method was restricted to the Middle East and Southeastern cohorts, whereas the Western and Japanese cohorts were studied by sample design and had considerably lower prevalence rates (3.6/ 100 000). Therefore, the impression that the prevalence of BD is up to 400-fold lower in Middle East and Southeastern countries must be seen in perspective. The only ethnic groups who were studied by both methods were Israeli cohorts, and they demonstrated about 2to 3-fold higher figures in sample surveys [6]. Interestingly, the prevalence figures among Turkish immigrants (71.2/ 100 000) acquired in a Western sample survey would equal those of Turkish studies when corrected with this factor [5]. Designed geographical boundaries of countries might conflict in more and potentially higher regional figures, i.e. local epidemiological studies might be more useful in locating the origin of BD. So far, the outcomes of the study by Maldini et al. put the prevalence differences between East and West in perspective since the true prevelances remain the highest there, but still support the hypothesis that the Middle Eastern region is where BD might have originated. Are there any clues other than prevalence figures to support the Silk Road and reverse migration theories? The foremost indication is the parallel occurrence of HLA-B51 with the Silk Road [3]. HLA-B51 still has the strongest genetic association with BD as compared to any other known genetic variations [7], elevating the odds of having BD to 5.8 [8], and this might shed light

Chronic signs of memory B cell activation in patients with Behçet’s disease are partially restored by anti-tumour necrosis factor treatment

Objectives. Behçet’s disease (BD), an auto-inflammatory vasculitis with oro-genital ulcerations, skin lesions and uveitis, is regarded as T cell mediated. A successful trial with rituximab suggests an additive role for B cells in the pathogenesis. Therefore, we studied B cell abnormalities in BD patients and the effect of TNF-blocking therapy. Methods. B cells in blood (n = 36) and tissue (n = 6) of BD patients were analysed with flow cytometry and/or immunohistochemistry and compared with healthy controls (n = 22). BD current activity form (BDCAF) in relation to B cell somatic hypermutations (SHMs) and immunoglobulin class-switching were studied. Results. Thirty-six patients (17 males) were included, mean age 44 years, average disease duration 10 years and mean BDCAF 2.7. Blood B cell numbers were significantly lower in patients than in controls (P = 0.0061), mostly due to decreased CD27+ memory B cells expressing IgM (P = 0.0001), IgG (P = 0.0002) and IgA (P = 0.0038) B cell subsets. CD27+ IgA+ B cells showed the highest magnitude of decrease in active disease, measured with BDCAF (P = 0.02). CD27+ IgM+ IgD+ B cells were impaired in replication history (P = 0.0133) and selection of SHM, whereas IgA+ B cells carried elevated SHM levels (P = 0.04) and lower IgA2 subclass usage (P = 0.0004) than controls. Immunohistochemistry revealed B cells in tissue of active mucosal ulcers. In adalimumab-treated patients, blood B cells were similar to controls. Conclusion. We show significant deviations in the memory B cell compartment, related to disease activity and therapeutic efficacy. Pronounced molecular impairments were seen in the fast-responding IgM+-memory and the mucosal IgA+-memory B cells. Because of the demonstrated abundance of B cells in affected tissue, we hypothesize relocation of memory B cells to the site of inflammation could account for the deviations found in blood of BD patients. These peripheral B cells are easily accessible as a marker to monitor therapeutic efficacy.

Prevalence of atopic diseases in patients with sarcoidosis.

It remains unclear whether atopy is associated with the occurrence of sarcoidosis or affects its severity. The purpose of this study was to compare the lifetime prevalence of atopic eczema, asthma, and hay fever in sarcoidosis patients with controls and to assess whether atopy influences the severity of sarcoidosis. The prevalence of atopic disorders assessed with a validated postal questionnaire in sarcoidosis patients with pulmonary, uveitis, and cutaneous sarcoidosis was compared with that of their domestic partners in a case-control study. The serological parameters, the pulmonary function tests, and the high-resolution computed tomography (HRCT) scans of atopic and nonatopic sarcoidosis patients were compared in a nested cohort. Multivariate logistic regression models were used to calculate the odds ratios (ORs) and the 95% confidence intervals (CIs). Two hundred twenty-five sarcoidosis patients and 177 controls were included. The prevalences of atopic eczema, asthma, and hay fever were comparable between patients and controls (12.4% versus 12.4%, 5.3% versus 5.6%, and 16.9% versus 15.8%, respectively). After adjusting for gender and ethnicity, those with sarcoidosis and a history of atopic eczema were significantly less likely to have uveitis (OR, 0.30; 95% CI, 0.13-0.71). Within the sarcoidosis cohort, the distributions of serological markers, the lung function tests, and the HRCT scans were similar between atopic and nonatopic patients. Atopy is not associated with the occurrence of sarcoidosis, but atopic eczema may decrease the likelihood of eye involvement.

To distinguish IgG4-related disease from seronegative granulomatosis with polyangiitis

_SIR,_ nIgG4-related disease (IgG4-RD) is a fibro-inflammatory disease that can affect almost every organ. Indeed, previous unexplained conditions have now been reclassified as primarily IgG4-RD and may imitate many inflammatory, infectious and malignant disorders often leading to a delay in diagnosis or incorrect diagnosis. Nasal manifestation of IgG4-RD, mostly of the paranasal sinuses, has previously been described in case reports, but it can also manifest as a primary or secondary nasal disease such as chronic sinusitis and paranasal sinusitis with dacryoadenitis. Since IgG4-RD localized in the nasal or orbital region remarkably resembles limited granulomatosis with polyangiitis (GPA), IgG4-RD could be an alternative diagnosis in ANCA negative limited GPA. After revising the diagnosis to IgG4-RD in patient 1, we re-evaluated two other ANCA negative patients from a funded database with similar clinical features and could alter the diagnosis into IgG4-RD. The histomorphological features matching IgG4-RD and absence of evident features of GPA were the reasons for immunohistochemical analysis in these cases leading to the diagnosis of IgG4-RD. [...]