Immunohistochemical expression of DnaJ homolog subfamily B member 9 in immunoglobulin G4-related disease: a pilot study.

OBJECTIVES: DnaJ homolog subfamily B member 9 (DNAJB9) is a co-chaperone protein that governs the functions and integrity of cells. In immunoglobulin G4-related disease (IgG4-RD), DNAJB9 was shown to be upregulated in plasma cells, but its immunohistochemical expression has never been explored. This pilot study aims to investigate the immunohistochemical distribution and intensity of DNAJB9 in IgG4-RD tissue specimens. METHODS: Patients with definite IgG4-RD and normal tissue controls were selected for anti-DNAJB9 immunohistochemistry, applying a semi-quantitative staining intensity score. RESULTS: We studied the tissue slides of 9 IgG4-RD patients and 15 controls, including salivary gland, pancreatic, pulmonary, pleural, and retroperitoneal fibrosis tissue. Median immunohistochemical intensity was 0 for IgG4-RD patients vs. 2 for controls for endothelial cells (ES=1.58, p<0.01), 2 in each group for glandular epithelial cells (ES 0.70, p=0.26), and 2 for IgG4-RD vs. 3 for controls for inflammatory cells regarding salivary glands alone (ES=0.90, p=0.11). Endothelial staining intensity was negatively correlated with serum IgG4 concentrations (r= -0.72, p=0.03) and the number of treatments required to achieve disease remission (r= -0.70, p=0.04). CONCLUSIONS: Our findings evidenced reduced immunohistochemical expression of DNAJB9 in IgG4-RD endothelial cells, and suggested loss of expression in other cell types, possibly correlating with disease severity and risk of relapse. Although DNAJB9 may not serve as a marker for IgG4-RD, it may be part of a pathophysiological pathway involved in the disease and the onset of fibrosis.

IgG4-related uveitis. A French cohort and literature review.

INTRODUCTION: IgG4-related disease (IgG4-RD) is a fibro-inflammatory disorder that can affect almost any organ. IgG4-related ophthalmic disease is a protean condition involving the orbit and ocular adnexa. Although a few cases of uveitis have been reported, the exact pattern of IgG4-related intraocular manifestations remains unclear. Here, we report on a nationwide French multicenter cohort of patients with IgG4-RD and uveitis and conducted a literature review. METHODS: Patients with uveitis and a concomitant definite diagnosis of IgG4-RD (Revised Comprehensive Diagnostic criteria, American College of Rheumatology/European League Against Rheumatism classification criteria for IgG4-RD, International Consensus Diagnostic Criteria for auto-immune pancreatitis, or diagnostic criteria for IgG4-related hypophysitis), were screened from our national IgG4-RD and systemic fibrosis database. Concomitantly, we conducted a PubMed literature review and selected cases of definite IgG4-RD with uveitis. RESULTS: We reported on 16 patients (8 from our database and 8 from the literature) and a total of 30 episodes of uveitis. Uveitis cases represented 3 % of total IgG4-RD patients in the national database on IgG4-RD and systemic fibrosis. Uveitis was inaugural in IgG4-RD in 4/16 cases (25 %) (appearing before any other IgG4-related symptom, at a median of 9 months), occurred concurrently to other IgG4-related symptoms in 9/16 cases (56 %) (at a median of 15 months before IgG4-RD diagnosis), and appeared during follow up in 3/16 patients (19 %) (at a median of 57 months after first IgG4-related symptoms). When uveitis occurred during follow up, it was associated with IgG4-RD manifestations in other organs in 6/9 patients (67 %). Uveitis was bilateral in 8/16 cases (50 %) and granulomatous in 5/10 cases (50 %). It was anterior in 8/13 (62 %), intermediate in 3/13 (23 %), and global (panuveitis) in 4/13 patients (31 %). Median serum IgG4 at diagnosis was 3.2 g/L. Median follow up time was of 6 years, during which 8/16 patients (50 %) experienced at least one relapse of uveitis. Treatment data was available for 29/30 uveitis flares. Steroids were used in 28/29 episodes of uveitis (97 %), leading to remission of uveitis in 16/28 cases (57 %). Methotrexate and rituximab (in combination with systemic steroids) were administered as second- or third-line therapy in 6/29 (21 %) and 5/29 (17 %) episodes of uveitis, respectively, and led to remission of uveitis in 4/6 cases (67 %) and 4/5 cases (80 %), respectively. One third of uveitides required at least two different lines of treatment for remission induction (mainly a combination of both systemic steroids and methotrexate or rituximab). DISCUSSION AND CONCLUSIONS: Uveitis may be one of the initial symptoms of IgG4-RD, and IgG4-RD should be considered in the diagnostic workup of uveitis. Its early onset in IgG4-RD may help with early diagnosis and treatment of the disease. Steroid monotherapy may be sufficient to treat IgG4-related uveitis, yet relapses were frequent (50 %) and ultimately a third of patients required at least two lines of treatment. Hence, steroid-sparing agents can be considered at early stages of the disease, particularly for patients with a high risk of relapse or steroid-related complications.