Clonal expansion of CD4(+) cytotoxic T lymphocytes in patients with IgG4-related disease

Immunoglobulin G4-related kidney disease: Pathogenesis, diagnosis, and treatment

Immunoglobulin G4-related disease (IgG4-RD) is a recently recognized clinical entity that often involves multiple organs; it is characterized by high levels of serum immunoglobulin G4 (IgG4), dense infiltration of IgG4+ cells, and storiform fibrosis. Cellular immunity, particularly T cell-mediated immunity, has been implicated in the pathogenesis of IgG4-RD. The most frequent renal manifestations of IgG4-RD are IgG4-related tubulointerstitial nephritis, membranous glomerulonephropathy (MGN), and obstructive nephropathy secondary to urinary tract obstruction due to IgG4-related retroperitoneal fibrosis, prostatitis, or ureter inflammation. Kidney function impairment can be acute or chronic. In IgG4-MGN, proteinuria can be in the nephrotic range. The diagnosis of IgG4-related kidney disease should not be based solely on serum IgG4 levels or the number of tissue-infiltrating IgG4+ plasma cells. Diagnosis should be based on specific histopathological findings, confirmed by tissue immunostaining and an appropriate clinical context. Steroid treatment is the first-line therapy. For relapsing or refractory cases, immunosuppressants could be combined with steroids. In hydronephrosis patients, appropriate immunosuppressive therapy could preclude the implantation of a double J ureteral catheter.

Association of IgG4-Related Disease With History of Malignancy

OBJECTIVE

IgG4-related disease (IgG4-RD) is a fibroinflammatory disease of unclear etiology. Some studies suggest that IgG4-RD predisposes patients to malignancy or is a forme fruste of cancer, but we have frequently observed IgG4-RD patients who have a history of malignancy preceding the clinical onset of IgG4-RD. This study was undertaken to characterize IgG4-RD in the setting of previous malignancy diagnosis.

METHODS

We identified IgG4-RD patients with a history of invasive malignancy from a well-defined cohort of 125 patients and compared their malignancy history to those of 2 reference groups. First, we calculated a standardized prevalence ratio against general US population estimates from the Surveillance, Epidemiology, and End Results (SEER) database. Second, we identified up to 5 age- and sex-matched controls for each case and calculated the odds of malignancy among those with IgG4-RD compared to controls, using conditional logistic regression.

RESULTS

The mean ± SD age at IgG4-RD onset was 50.3 ± 14.9 years, and 61% of the patients were male. Twenty (16%) had been diagnosed as having malignancies (total 21 malignancies) before the diagnosis of IgG4-RD. The observed prevalence of malignancy in this cohort was 2.5 times higher (95% confidence interval [95% CI] 1.1-3.6) than expected compared to the SEER database. Compared to matched controls, the frequency of history of malignancy was >3-fold higher in IgG4-RD patients (95% CI 1.6-6.2).

CONCLUSION

Our findings suggest that, in a subset of patients with IgG4-RD, malignancy may be associated with subsequent IgG4-RD development. Potential explanations include shared risk factors for both IgG4-RD and cancer, the triggering by cancer of autoantigen expression leading to IgG4-RD, and an increased risk of IgG4-RD resulting from cancer treatment.

IgG4-related disease of the biliary tract and pancreas: clinical and experimental advances

PURPOSE OF REVIEW

IgG4-related disease (IgG4-RD) is an immune-mediated disease of unknown cause. It predominantly affects the biliary tract [IgG4-associated cholangitis (IAC)] and pancreas [autoimmune pancreatitis (AIP)] of mostly elderly men. Accurate diagnostic tests are lacking. Patients benefit from predniso(lo)ne treatment. However, disease relapse is often seen. This review will address pathophysiological aspects and advances in diagnostic and therapeutic strategies.

RECENT FINDINGS

The role of IgG1 and IgG4 in the pathophysiology of IgG4-RD was studied in mice which showed more intense organ damage of pancreas and salivary glands when IgG1 rather than IgG4 of patients with IgG4-RD was injected. Coadministration of IgG1+IgG4 led to dampening of IgG1-mediated injury supporting the view that IgG4 exerts immune-dampening effects. IgG4+ B-cell receptor clones identified by next-generation sequencing and the IgG4/IgG RNA ratio in human blood assessed by quantitative PCR were able to accurately distinguish IAC/AIP from primary sclerosing cholangitis or pancreatobiliary malignancies. Long-term treatment with low-dose prednisolone was safe and reduced the number of flare-ups in patients with AIP.

SUMMARY

Early diagnosis by a novel accurate and easy-to-use qPCR test may prevent life-threatening complications, unnecessary interventions and fatal course because of misdiagnosis. Prednisolone treatment remains the standard of care in patients with IgG4-RD.

IgG4-related Disease and the Liver

Pathologists are likely to encounter IgG4-related disease in several organ systems. This article focuses on helping pathologists diagnose IgG4-related disease in the hepatobiliary system. Missing the diagnosis can result in unnecessary organ damage and/or unnecessary surgical and cancer therapy. In the liver, tumefactive lesion(s) involving the bile ducts with storiform fibrosis and an IgG4-enriched lymphoplasmacytic infiltrate are highly concerning for IgG4-related disease. The recent identification of oligoclonal populations of T cells and B cells in IgG4-related disease may lead to molecular tests, new therapeutics, and a greater mechanistic understanding of the disease.

Treatment of IgG4-related disease : Current and future approaches

IgG4-related disease (IgG4-RD) is capable of causing great morbidity and even mortality if the condition remains undiagnosed or poorly treated, yet is typically a treatment-responsive disorder. Glucocorticoids have not been studied rigorously and practices with regard to dosing and duration of treatment remain largely empiric. In addition, IgG4-RD patients are often particularly susceptible to and intolerant of the deleterious effects of glucocorticoid therapy. B cell depletion with anti-CD20 monoclonal antibodies appears to be a rapid, effective means of obtaining disease control and limiting patients' glucocorticoid exposure, but this option is frequently not available. Other therapies targeting the B cell lineage may also be efficacious, and one is under study. The means by which depletion or inhibition of B cells and their progeny ameliorate IgG4-RD is coming into focus now through careful mechanistic studies of samples from treated patients. The mechanistic understanding of IgG4-RD will bring an array of specific targets for therapeutic intervention. Plasmablast-directed therapy with a CD19 monoclonal antibody is currently in clinical trials. CD4 + cytotoxic T lymphocytes and fibrosis, both observed nearly universally in the tissue of IgG4-RD patients, present two unexploited vulnerabilities in controlling and even reversing the effects of the disease. Further development of such therapies is a major goal of the next few years.

High Expression of Galectin-3 in Patients with IgG4-Related Disease: A Proteomic Approach

Objectives

Immunoglobulin G4-related disease (IgG4-RD) is a multiorgan condition manifesting itself in different forms. This study aimed to investigate protein expression profiles and to find the possible biomarker for IgG4-RD by liquid chromatography mass spectrometry (LC-MS) using tissue sections in IgG4-RD patients.

Methods

Protein expression profiles in five IgG4-related pancreatitis and three normal pancreatic samples were compared using LC-MS and were validated by quantitative real-time PCR (qRT-PCR), immunoblotting, and immunohistochemistry. ELISA was employed in the serum of 20 patients with systemic IgG4-RD before and during steroid treatment.

Results

LC-MS indicated that the levels of 17 proteins were significantly higher and 12 others were significantly lower in IgG4-related pancreatitis patients compared to controls. Among these proteins, galectin-3 levels were 13-fold higher in IgG4-related pancreatitis (P < 0.01). These results were confirmed by immunoblotting and qRT-PCR. The average number of galectin-3 + cells in various organs of IgG4-RD patients, including salivary glands, lungs, and lymph nodes, was higher than in controls. Galectin-3 was detectable in macrophages, dendritic cells, and stromal myofibroblast-like cells, but not in lymphocytes by immunofluorescence staining. Serum galectin-3 levels were higher in patients with IgG4-RD compared with healthy donors and remained high during steroid therapy.

Conclusion

Galectin-3 was overexpressed in IgG4-RD and the levels were indirectly related to clinical activity.

IgG4-related disease in autoimmune lymphoproliferative syndrome

A patient with autoimmune lymphoproliferative disorder (ALPS) developed IgG4-related disease. In retrospect, he had high levels of serum IgG4 for several years prior to presenting with IgG4-related pancreatitis. These high IgG4 levels were masked by hypergammaglobulinemia, a common feature of ALPS. We next screened 18 ALPS patients; four of them displayed increased levels of IgG4. Hence, IgG4-related disease should be considered in ALPS patients, especially in those manifesting lymphocytic organ infiltration or excessive hypergammaglobulinaemia. Screening of IgG4-related disease patients for ALPS-associated mutations would provide further information on whether this disease could be a late-onset atypical presentation of ALPS.

IgG4-related disease

PURPOSE OF REVIEW

Remarkable insights have been gleaned recently with regard to the pathophysiology of IgG4-related disease (IgG4-RD). These findings have direct implications for the development of targeted strategies for the treatment of this condition.

RECENT FINDINGS

Oligoclonal expansions of cells of both the B and T lymphocyte lineages are present in the blood of patients with IgG4-RD. Oligoclonal expansions of plasmablasts are a good biomarker for disease activity. An oligoclonally expanded population of CD4+ cytotoxic T lymphocytes is found not only in the peripheral blood but also at tissue sites of active disease. This cell elaborates cytokines that may drive the fibrosis characteristic of IgG4-RD. T follicular helper cells (Tfhc), particularly the Tfhc2 subset, appear to play a major role in driving the class switch to IgG4 that typifies this disease. The relationship between malignancy and IgG4-RD remains an area of interest.

SUMMARY

Advances in understanding the pathophysiology of IgG4-RD have proceeded swiftly, leading to the identification of a number of potential targeted treatment strategies. The completion of classification criteria for IgG4-RD, an effort supported jointly by the American College of Rheumatology and the European League Against Rheumatism, will further facilitate studies on this disease.

Neurological Manifestations of IgG4-Related Disease

OPINION STATEMENT

IgG4-related disease (IgG4-RD) is a multisystem inflammatory disorder. Early recognition of IgG4-RD is important to avoid permanent organ dysfunction and disability. Neurological involvement by IgG4-RD is relatively uncommon, but well recognised-hypertrophic pachymeningitis and hypophysitis are the most frequent manifestations. Although the nervous system may be involved in isolation, this more frequently occurs in conjunction with involvement of other systems. Elevated circulating levels of IgG4 are suggestive of the condition, but these are not pathognomonic and exclusion of other inflammatory disorders including vasculitis is required. Wherever possible, a tissue diagnosis should be established. The characteristic histopathological changes include a lymphoplasmacytoid infiltrate, storiform fibrosis and obliterative phlebitis. IgG4-RD typically responds well to treatment with glucocorticoids, although relapse is relatively common and treatment with a steroid-sparing agent or rituximab may be required. Improved understanding of the pathogenesis of IgG4-RD is likely to lead to the development of more specific disease treatments in the future.

T Cell Polarization toward TH2/TFH2 and TH17/TFH17 in Patients with IgG4-Related Disease

IgG4-related disease (IgG4-RD) is a fibro-inflammatory disorder involving virtually every organ with a risk of organ dysfunction. Despite recent studies regarding B cell and T cell compartments, the disease’s pathophysiology remains poorly understood. We examined and characterized subsets of circulating lymphocytes in untreated patients with active IgG4-RD. Twenty-eight consecutive patients with biopsy-proven IgG4-RD were included in a prospective, multicentric study. Lymphocytes’ subsets were analyzed by flow cytometry, with analysis of T_H1/T_H2/T_H17, T_FH cells, and cytokine release by peripheral blood mononuclear cells. Results were compared to healthy controls and to patients with primary Sjögren’s syndrome. Patients with IgG4-RD showed an increase of circulating T regulatory, T_H2, T_H17, and CD4⁺CXCR5⁺PD1⁺ T_FH cell subsets. Accordingly, increased levels of IL-10 and IL-4 were measured in IgG-RD patients. T_FH increase was characterized by the specific expansion of T_FH2 (CCR6⁻CXCR3⁻), and to a lesser extent of T_FH17 (CCR6⁺CXCR3⁻) cells. Interestingly, CD4⁺CXCR5⁺PD1⁺ T_FH cells normalized under treatment. IgG4-RD is characterized by a shift of circulating T cells toward a T_H2/T_FH2 and T_H17/T_FH17 polarization. This immunological imbalance might be implicated in the disease’s pathophysiology. Treatment regimens targeting such T cells warrant further evaluation.

Ophthalmic manifestations in IgG4-related disease: Clinical presentation and response to treatment in a French case-series

IgG4-related disease (IgG4-RD) is characterized by variable tissue or organ involvements sharing common pathological findings. Orbital or orbital adnexa involvement of the disease has been reported in a few case series. The aim of our study was to characterize and analyze ophthalmic manifestations from a nationwide French case-series.Patients with IgG4-RD and orbital or orbital adnexa involvement included in the French multicentric IgG4-RD case-registry were identified. Only patients fulfilling "modified" comprehensive diagnostic criteria with pathological documentation were retained for the study. Clinical, biological, pathological, radiological findings and data regarding the response to treatment were retrospectively analyzed.According to our data registry, the frequency of IgG4-related ophthalmic disease (IgG4-ROD) was 17%. Mean age at diagnosis was 55.1 ± 7.1 years with a male/female ratio of 2.2. The 19 cases of IgG4-ROD consisted of lacrimal gland (68.4%), soft tissue (57.9%), extra-ocular muscles (36.8%), palpebral (21.1%), optical nerve (10.5%), orbital bone (10.5%), and mononeuritis (V1 and/or V2, 10.5%) involvements. IgG4-ROD was bilateral in 57.9% of cases. Extra-ophthalmic manifestations were reported in 78.9% of cases. All patients responded to prednisone but two-thirds of patients relapsed within a mean (SD) of 9.8 (3.5) months and 72.2% required long-term glucocorticoids and/or immunosuppressive agents. Eight patients were treated by rituximab with a favorable response in 87.5% of cases.Lacrimal involvement is the most frequent ophthalmic manifestation of IgG4-RD and is frequently associated with extra-orbital manifestations. Despite initial favorable response to steroids, the long-term management of relapsing patients needs to be improved.

Recent advances in understanding and managing IgG4-related disease

IgG4-related disease was only recently discovered, so its description, management, and new discoveries related to its etiology are rapidly evolving. Because IgG4 itself is a unique antibody which is intimately related to the diagnosis of the disease, the role of plasmablasts in the pathophysiology remains an active area of discussion. Recent studies have uncovered a possible role for CD4-positive cytotoxic T lymphocytes, T follicular helper cells, and M2 macrophages. The clinical presentation is variable and can be vague, as this disease affects many organs and new presentations are continuing to be described. The diagnosis depends on clinical and histopathological assessment. The mainstay of treatment is with glucocorticoids, but rituximab has recently shown promise. Monitoring disease activity using imaging modalities (including positron emission tomography) and serum markers is imperative, as relapses are common. IgG4-related disease spans many medical disciplines but is a treatable condition with which all clinicians should be familiar.

Interleukin-33 produced by M2 macrophages and other immune cells contributes to Th2 immune reaction of IgG4-related disease

IgG4-related disease (IgG4-RD) is characterized by elevated serum IgG4 and marked infiltration of IgG4-positive cells in multiple organs. Interleukin-33 (IL-33) is a recently described cytokine that is secreted by damaged epithelial cells, macrophages, and dendritic cells, and potently activates helper T type 2 (Th2) immune responses, which have been suggested to play a major role in IgG4 production of IgG4-RD. Here, we assessed the expression of IL-33 and related molecules in the salivary glands (SGs) of patients with IgG4-RD versus that in patients with Sjögren's syndrome (SS) and controls. Expression of IL-33 and its receptor (ST2) was strongly detected around ectopic germinal centers (GCs) in the SGs from patients with IgG4-RD, whereas IL-33 was expressed only in epithelial cells in patients with SS and controls. Moreover, IL-33 and CD68⁺/CD163⁺ macrophages were mainly distributed around ectopic GCs in patients with IgG4-RD. Double immunofluorescence staining showed that IL-33 expression co-localized with CD68⁺/CD163⁺ macrophages. Finally, mRNA expression levels of IL-33 showed a positive correlation to those of Th2 cytokines (IL-4 and IL-13) in patients with IgG4-RD. Our data suggest that IL-33 produced by M2 macrophages might contribute to the pathogenesis of IgG4-RD via aberrant activation of Th2 immune responses.

Is MuSK myasthenia gravis linked to IgG4-related disease?

Immunoglobulin (Ig) G4-related disease (IgG4-RD) is an immune-mediated inflammatory condition that affects a wide variety of sites, including the nervous system, where it can involve the meninges or the pituitary gland, and cause perineural mass lesions. A large subset of acetylcholine receptor antibody (Ab)-negative myasthenia gravis (MG) patients has muscle-specific tyrosine kinase (MuSK) Abs, generally of the IgG4 subclass. There has not been any association found between IgG4-RD and MuSK MG yet. We report the first case of MuSK MG associated with lymphadenopathy with histopathology consistent with IgG4-RD. A 54-year-old woman with MuSK MG developed eight compression fractures related to steroid therapy. Eighteen months after initial presentation she was found to have retroperitoneal lymphadenopathy with biopsy findings consistent with IgG4-RD. She was started on rituximab with clinical improvement and ability to taper immunomodulatory agents for the first time. Our case raises number of questions regarding a potential link between MuSK MG and IgG4-RD which may shed further light on the pathophysiology and management of these diseases.

Lesional CD4+ IFN-γ+ cytotoxic T lymphocytes in IgG4-related dacryoadenitis and sialoadenitis

OBJECTIVES

IgG4-related disease (IgG4-RD) is a chronic, systemic, inflammatory condition of unknown aetiology. We have recently described clonally expanded circulating CD4+ cytotoxic T lymphocytes (CTLs) in IgG4-RD that infiltrate affected tissues where they secrete interleukin (IL)-1β and transforming growth factor -β1 (TGF-β1). In this study, we sought to examine the role of CD4+ CTLs in the pathogenesis of IgG4-related dacryoadenitis and sialoadenitis (IgG4-DS) and to determine whether these cells secrete interferon-gamma (IFN-γ) at lesional sites.

METHODS

Salivary glands of 25 patients with IgG4-DS, 22 patients with Sjögren's syndrome (SS), 12 patients with chronic sialoadenitis (CS) and 12 healthy controls were analysed in this study. Gene expression analysis was performed on submandibular glands (SMGs) from five patients with IgG4-DS, three with CS and three healthy controls. Infiltrating CD4+ CTLs were examined by quantitative multicolour imaging in tissue samples from 20 patients with IgG4-DS, 22 patients with SS, 9 patients with CS and 9 healthy controls.

RESULTS

In IgG4-DS tissues, nine genes associated with CD4+ CTLs were overexpressed. The expression of granzyme A (GZMA) mRNA was significantly higher in samples from patients with IgG4-RD compared with corresponding tissues from SS and healthy controls. Quantitative imaging showed that infiltrating CD4+ GZMA+ CTLs were more abundant in patients with IgG4-DS than in the other groups. The ratio of CD4+GZMA+ CTLs in SMGs from patients with IgG4-DS correlated with serum IgG4 concentrations and the number of affected organs. A large fraction of CD4+GZMA+ CTLs in SMGs from patients with IgG4-DS secreted IFN-γ.

CONCLUSIONS

The pathogenesis of IgG4-DS is associated with tissue infiltration by CD4+GZMA+ CTLs that secrete IFN-γ.

IgG4-Related Disease Presenting as Isolated Scleritis

A rare case of IgG4-related disease (IgG4-RD) manifesting as nodular scleritis is presented in a 20-year-old female. Patient complained of left eye pain and redness for one week. Ocular examination together with ancillary testing led to the diagnosis of nodular scleritis. Since the patient did not show apparent improvement after one week of systemic steroidal treatment, she underwent a biopsy of the affected area revealing histopathological characteristics of IgG4-RD. Long-term treatment with corticosteroids and a steroid-sparing agent (methotrexate) led to significant improvement in signs and symptoms. This case highlights the significance of IgG4-RD in the differential diagnosis of scleritis and raises the question as to whether various organs affected by IgG4-RD may have different underlying pathophysiological mechanisms in which pathogenic T cells play a role.

Overview of IgG4 - Related Disease

Rationale (hypothesis): IgG4-related disease (IgG4-RD) is a pathological entity recently recognized by the medical world that can affect any organ or system. However, there is insufficient data about this disease in medical literature. Aim (objective): A more extensive clarification of the IgG4 molecule, the diversified aspects of IgG4-related disease, and the response of this disease to treatment, will provide a crucial understanding of the immune system and other diseases now known to be associated with IgG4.

METHODS AND RESULTS

The MEDLINE online medical database was used, and, after a comprehensive review of medical articles regarding IgG4-RD, published after 2003, using the search words "IgG4- related disease" and "IgG4 molecule", we have described the clinical, pathological and therapeutic features of IgG4-RD, as well as the presence of the IgG4 molecule in the evolution, diagnosis and management of this syndrome. We characterized the potential disease mechanisms and discussed early observations related to treatment.

DISCUSSION

Given the response to immunosuppressive therapy, it is hypothesized that IgG4-related disease is most likely an autoimmune disease. Therefore, IgG4-related disease is a fibro-inflammatory condition that can affect any organ and can lead to the formation of pseudotumoral lesions requiring differential diagnosis with various malignancies. Positive diagnostic criteria are histopathological and require at least two features out of the following three: dense limphoplasmocitary infiltrate, storiform fibrosis, obliterative phlebitis.

Recent advances in knowledge regarding the head and neck manifestations of IgG4-related disease

IgG4-related disease (IgG4-RD) is a chronic inflammatory disorder, characterized by elevated serum IgG4 levels as well as abundant infiltration of IgG4-positive plasmacytes and fibrosis in various organs, including the head and neck region. In particular, the salivary glands, orbit, and thyroid are common sites of disease involvement. IgG4-RD is diagnosed based on various clinical, serological, and histopathological findings, none of which are pathognomonic. Hence, various differential diagnoses, which exhibit elevated serum IgG4 levels and infiltration of IgG4-postive cells into tissues, need to be excluded, especially malignant diseases and mimicking disorders. Systemic corticosteroids are generally effective in inducing IgG4-RD remission; however, recurrent or refractory cases are common. In addition, although the pathogenic mechanisms of IgG4-RD remain unclear, an antigen-driven inflammatory condition is believed to be involved. Recent studies have indicated the important pathogenic role of B cell/T cell collaboration and innate immunity in this disease. Nevertheless, additional research and discussions are needed to resolve many remaining questions. In this review, we provide an overview of the recent insights on the history, clinical features, diagnosis, and treatment of IgG4-RD in the head and neck region. Furthermore, we have also addressed the pathogenesis of this disease.

IgG4-related hepatobiliary disease: an overview

IgG4-related hepatobiliary diseases are part of a multiorgan fibroinflammatory condition termed IgG4-related disease, and include IgG4-related sclerosing cholangitis (IgG4-SC) and IgG4-related hepatopathy. These diseases can present with biliary strictures and/or mass lesions, making them difficult to differentiate from primary sclerosing cholangitis (PSC) or other hepatobiliary malignancies. Diagnosis is based on a combination of clinical, biochemical, radiological and histological findings. However, a gold standard diagnostic test is lacking, warranting the identification of more specific disease markers. Novel assays - such as the serum IgG4:IgG1 ratio and IgG4:IgG RNA ratio (which distinguish IgG4-SC from PSC with high serum IgG4 levels), and plasmablast expansion to recognize IgG4-SC with normal serum IgG4 levels - require further validation. Steroids and other immunosuppressive therapies can lead to clinical and radiological improvement when given in the inflammatory phase of the disease, but evidence for the efficacy of treatment regimens is limited. Progressive fibrosclerotic disease, liver cirrhosis and an increased risk of malignancy are now recognized outcomes. Insights into the genetic and immunological features of the disease have increased over the past decade, with an emphasis on HLAs, T cells, circulating memory B cells and plasmablasts, chemokine-mediated trafficking, as well as the role of the innate immune system.

Large vessel involvement by IgG4-related disease

OBJECTIVES

IgG4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory condition that can affect multiple organs and lead to tumefactive, tissue-destructive lesions. Reports have described inflammatory aortitis and periaortitis, the latter in the setting of retroperitoneal fibrosis (RPF), but have not distinguished adequately between these 2 manifestations. The frequency, radiologic features, and response of vascular complications to B cell depletion remain poorly defined. We describe the clinical features, radiology findings, and treatment response in a cohort of 36 patients with IgG4-RD affecting large blood vessels.

METHODS

Clinical records of all patients diagnosed with IgG4-RD in our center were reviewed. All radiologic studies were reviewed. We distinguished between primary large blood vessel inflammation and secondary vascular involvement. Primary involvement was defined as inflammation in the blood vessel wall as a principal focus of disease. Secondary vascular involvement was defined as disease caused by the effects of adjacent inflammation on the blood vessel wall.

RESULTS

Of the 160 IgG4-RD patients in this cohort, 36 (22.5%) had large-vessel involvement. The mean age at disease onset of the patients with large-vessel IgG4-RD was 54.6 years. Twenty-eight patients (78%) were male and 8 (22%) were female. Thirteen patients (36%) had primary IgG4-related vasculitis and aortitis with aneurysm formation comprised the most common manifestation. This affected 5.6% of the entire IgG4-RD cohort and was observed in the thoracic aorta in 8 patients, the abdominal aorta in 4, and both the thoracic and abdominal aorta in 3. Three of these aneurysms were complicated by aortic dissection or contained perforation. Periaortitis secondary to RPF accounted for 27 of 29 patients (93%) of secondary vascular involvement by IgG4-RD. Only 5 patients demonstrated evidence of both primary and secondary blood vessel involvement. Of those treated with rituximab, a majority responded positively.

CONCLUSIONS

IgG4-RD is a distinctive, unique, and treatable cause of large-vessel vasculitis. It can also involve blood vessels secondary to perivascular tumefactive lesions. The most common manifestation of IgG4-related vasculitis is aortitis with aneurysm formation. The most common secondary vascular manifestation is periaortitis with relative sparing of the aortic wall. Both primary vasculitis and secondary vascular involvement respond well to B cell depletion therapy.