An elevated IgG4 response in chronic infectious aortitis is associated with aortic atherosclerosis

Challenges and pitfalls in the diagnosis of IgG4-related disease

IgG4-related disease (IgG4-RD) is a relatively novel fibroinflammatory condition characterized typically by dense lymphoplasmacytic inflammation, storiform fibrosis and obliterative venulitis, together with prominent IgG4+ plasma cells and an IgG4+/IgG+ plasma cell ratio of >40 %. The diagnosis is usually made on a combination of clinical and serological features together with characteristic radiological and histological appearances. The condition may be limited to a single tissue/organ (e.g., autoimmune pancreatitis) or may be multicentric in nature - four clinical 'patterns' of disease distribution have recently been described. The diagnosis of IgG4-RD can be challenging, particularly when the clinical presentation is unusual and/or when the histological features are not typical. A diagnosis of IgG4-RD may still be achieved in these situations, after careful clinicopathological discussion e.g., at a specialist multidisciplinary team meeting. However, a wide range of other conditions (neoplastic and non-neoplastic) can mimic IgG4-RD, clinically and/or on histological examination. The relationship between IgG4-RD and non-IgG4-RD associated conditions in some clinical situations is particularly complex. This review describes the role of histological examination in the diagnosis of IgG4-RD, discusses some of the practical difficulties that may be encountered and provides an insight into the range of non-IgG4-RD associated conditions that can mimic IgG4-RD on clinical and/or histological grounds. The requirement for interpretation of histological features in the context of the global clinical picture of the patient is highlighted and emphasized.

Antibody Subclass and Glycosylation Shift Following Effective TB Treatment

With an estimated 25% of the global population infected with Mycobacterium tuberculosis (Mtb), tuberculosis (TB) remains a leading cause of death by infectious diseases. Humoral immunity following TB treatment is largely uncharacterized, and antibody profiling could provide insights into disease resolution. Here we focused on the distinctive TB-specific serum antibody features in active TB disease (ATB) and compared them with latent TB infection (LTBI) or treated ATB (txATB). As expected, di-galactosylated glycan structures (lacking sialic acid) found on IgG-Fc differentiated LTBI from ATB, but also discriminated txATB from ATB. Moreover, TB-specific IgG4 emerged as a novel antibody feature that correlated with active disease, elevated in ATB, but significantly diminished after therapy. These findings highlight 2 novel TB-specific antibody changes that track with the resolution of TB and may provide key insights to guide TB therapy.

A strobe multicenter descriptive study of 55 infectious aortitis

Infectious aortitis (IA) is a rare and severe disease. The treatment classically associates open surgery with prolonged antibiotic therapy. This study aimed to describe clinical characteristics, medical and surgical supports in a large and current series of IA.We conducted a retrospective multicenter study of native aorta IA, between 2000 and 2019. Inclusion criteria were the presence of a microorganism on blood culture, aortic sample or any other validated technique and structural anomaly in imaging.We included 55 patients (85% men), with a median age of 65. Microbiology data substantially differed from previous studies with 12 Gram-negative rods IA, of which only 3 due to Salmonella spp., 24 Gram-positive cocci IA of which 12 Streptococcus spp., and 18 IA due to intracellular growth and/or fastidious microorganisms, of which 8 Coxiella burnetii, 3 Treponema pallidum, and 5 tuberculosis suspicious cases. Fifteen patients (27%) presented with thoracic IA, 31 (56%) with abdominal IA, and 9 (16%) with thoraco-abdominal IA. Eight patients had no surgery, 41 underwent open surgery, only 4 endovascular aneurysm repair, and 2 a combination of these 2 techniques. Nine patients died before 1-month follow-up. There was no difference in the mortality rate between the different types of germ or localization of IA.The variety of germs involved in IA increases. Positron emission tomography-computed tomography scan is a very useful tool for diagnosis. Surgery is still mainly done in open approach and a prospective multicenter study seems necessary to better determine the place of endovascular aneurysm repair versus open surgery.

[IgG4-related disease: Diagnostic criteria evolution toward the 2019 ACR/EULAR classification criteria]

The concept of IgG4-related disease (IgG4-RD) has recently been individualized in the early 2000s, but most of the organ involvements are known since more than 100 years. IgG4-RD is a non-malignant fibroinflammatory disorder, characterized by peculiar immunological and pathological abnormalities, which can affect virtually all organs or tissues. Diagnostic criteria have been proposed and have evolved rapidly, with general or organ specific criteria. An international and multidisciplinary group assembled by the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR) has recently developed and validated a set of classification criteria called 2019 ACR/EULAR classification criteria for IgG4-related disease. The objective of this review is to discuss the evolution from organ specific and general diagnostic criteria toward the 2019 ACR/EULAR classification criteria, as well as respective benefits and limits of these criteria. The use of the 2019 ACR/EULAR classification criteria will help to better define homogeneous group of IgG4-RD patients in future clinical, epidemiological and basic science research studies on the disease.

Clinically isolated aortitis: pitfalls, progress, and possibilities

Non-infectious aortitis may be caused by several distinct systemic rheumatologic diseases. In some patients, aortitis is identified either pathologically or radiologically in the absence of clinical evidence of a systemic vasculitis. By consensus nomenclature, such cases are referred to as clinically isolated aortitis (CIA). Some systemic disorders may initially present as CIA including giant cell arteritis (GCA), IgG4-related disease, infectious aortitis, and granulomatosis with polyangiitis. CIA most commonly occurs in women of European descent over the age of 50 and, thus, mirrors the gender, age, and geographic distribution of GCA. CIA most often demonstrates a granulomatous/giant cell pattern of inflammation (GPI), and CIA-GPI is pathologically indistinguishable from aortitis due to GCA. In many cases, CIA may be a manifestation of extracranial GCA. CIA is being identified both pathologically in resected aortic tissue and radiologically by computed tomography scanning, magnetic resonance imaging, and fluorodeoxyglucose positron emission tomography. However, there appears to be significant differences between pathologically defined CIA and radiologically defined CIA. Multiple studies have shown that patients with CIA are at increased risk for subsequent aortic events (new aneurysms or dissections) and thus it is recommended to monitor these patients with periodic aortic imaging. While the data is currently limited, there is increasing evidence that at least some patients with CIA may benefit from immunosuppressive therapy.

[Takayasu's disease in an IgG4-positive patient with tuberculosis, pulmonary hemorrhage, recurrent myocarditis, and transient bilateral visual impairments]

Takayasu's disease (nonspecific aortoarteritis) affects the absolute majority of 20-40-year-old women; its most common manifestations include aortic arch branch lesions. The specific features of the described case is the male gender of the patient, signs of mesenchymal dysplasia, a concurrence of tuberculosis, pulmonary hemorrhage, and myocarditis at onset, the presence of IgG4, peculiar ocular symptomatology, and its rapid regression after initiation of therapy.