Vasculitis: determinants of disease patterns

The vasculitides are a large group of heterogeneous diseases for which it has been assumed that pathogenesis is largely autoimmune. As clinicians, we distinguish one form of vasculitis from another on the basis of observed patterns of organ injury, the size of the vessels affected and histopathological findings. The terms 'small-vessel', 'medium-vessel' and 'large-vessel' vasculitis are useful clinical descriptors, but fail to inform us about why vessels of a certain calibre are favoured by one disease and not another. Classification based on vessel size also fails to consider that vessels of a specific calibre are not equally prone to injury. Distinct vulnerabilities undoubtedly relate to the fact that same-size vessels in different tissues may not be identical conduits. In fact, vessels become specialized, from the earliest stages of embryonic development, to suit the needs of different anatomical locations. Vessels of the same calibre in different locations and organs are as different as the organ parenchymal cells through which they travel. The dialogue between developing vessels and the tissues they perfuse is designed to meet special local needs. Added to the story of vascular diversity and vulnerability are changes that occur during growth, development and ageing. An improved understanding of the unique territorial vulnerabilities of vessels could form the basis of new hypotheses for the aetiopathogenesis of the vasculitides. This Review considers how certain antigens, including infectious agents, might become disease-relevant and how vascular diversity could influence disease phenotypes and the spectrum of vascular inflammatory diseases.

High-resolution MRI vessel wall imaging: spatial and temporal patterns of reversible cerebral vasoconstriction syndrome and central nervous system vasculitis

BACKGROUND AND PURPOSE

High-resolution MR imaging is an emerging tool for evaluating intracranial artery disease. It has an advantage of defining vessel wall characteristics of intracranial vascular diseases. We investigated high-resolution MR imaging arterial wall characteristics of CNS vasculitis and reversible cerebral vasoconstriction syndrome to determine wall pattern changes during a follow-up period.

MATERIALS AND METHODS

We retrospectively reviewed 3T-high-resolution MR imaging vessel wall studies performed on 26 patients with a confirmed diagnosis of CNS vasculitis and reversible cerebral vasoconstriction syndrome during a follow-up period. Vessel wall imaging protocol included black-blood contrast-enhanced T1-weighted sequences with fat suppression and a saturation band, and time-of-flight MRA of the circle of Willis. Vessel wall characteristics including enhancement, wall thickening, and lumen narrowing were collected.

RESULTS

Thirteen patients with CNS vasculitis and 13 patients with reversible cerebral vasoconstriction syndrome were included. In the CNS vasculitis group, 9 patients showed smooth, concentric wall enhancement and thickening; 3 patients had smooth, eccentric wall enhancement and thickening; and 1 patient was without wall enhancement and thickening. Six of 13 patients had follow-up imaging; 4 patients showed stable smooth, concentric enhancement and thickening; and 2 patients had resoluton of initial imaging findings. In the reversible cerebral vasoconstriction syndrome group, 10 patients showed diffuse, uniform wall thickening with negligible-to-mild enhancement. Nine patients had follow-up imaging, with 8 patients showing complete resolution of the initial findings.

CONCLUSIONS

Postgadolinium 3T-high-resolution MR imaging appears to be a feasible tool in differentiating vessel wall patterns of CNS vasculitis and reversible cerebral vasoconstriction syndrome changes during a follow-up period.

Pegloticase immunogenicity: the relationship between efficacy and antibody development in patients treated for refractory chronic gout

INTRODUCTION

The efficacy of pegloticase, a polyethylene glycol (PEG)-conjugated mammalian recombinant uricase, approved for chronic refractory gout, can be limited by the development of antibodies (Ab). Analyses from 2 replicate, 6-month, randomized controlled trials were performed to characterize Ab responses to pegloticase.

METHODS

Anti-pegloticase, anti-PEG, and anti-uricase Ab were determined by validated enzyme-linked immunosorbent assays. Ab titers were analyzed for possible relationships with serum pegloticase concentrations, serum uric acid (sUA) lowering, and risk of infusion reactions (IRs).

RESULTS

Sixty-nine (41%) of 169 patients receiving pegloticase developed high titer anti-pegloticase Ab (> 1:2430) and 40% (67/169) developed anti-PEG Ab; 1 patient receiving placebo developed high titer anti-pegloticase Ab. Only 14% (24/169) of patients developed anti-uricase Ab, usually at low titer. In responders, patients showing sustained UA lowering, mean anti-pegloticase titers at week 25 (1:837 ± 1687 with biweekly and 1:2025 ± 4506 with monthly dosing) were markedly lower than in nonresponders (1:34,528 ± 42,228 and 1:89,658 ± 297,797, respectively). Nonresponder status was associated with reduced serum pegloticase concentrations. Baseline anti-pegloticase Ab, evident in 15% (31/212) of patients, did not predict subsequent loss of urate-lowering response. Loss of sUA response preceded IRs in 44 of 56 (79%) pegloticase-treated patients.

CONCLUSIONS

Loss of responsiveness to pegloticase is associated with the development of high titer anti-pegloticase Ab that increase clearance of pegloticase and are associated with a loss of the sUA lowering effect and increased IR risk. Pre-infusion sUA can be used as a surrogate for the presence of deleterious anti-pegloticase Ab.

TRIAL REGISTRATION

NCT00325195. Registered 10 May 2006, NCT01356498. Registered 27 October 2008.

Diagnosis and classification of central nervous system vasculitis

Central nervous system vasculitis is one of the foremost diagnostic challenges in rheumatology. It results in inflammation and destruction of the vasculature within the CNS. When vasculitis is confined to brain, meninges or spinal cord, it is referred to as primary angiitis of the CNS. Secondary CNS vasculitis occurs in the setting of a systemic vasculitis, auto-inflammatory or infectious disease. Prompt and accurate diagnosis of CNS vasculitis is essential to prevent irreversible brain damage, and to secure precise treatment decisions. Progressive debilitating and unexplained neurological deficits, associated with abnormal cerebrospinal fluid is the typical picture of the disease. Biopsy of the brain remains the gold standard diagnostic test. The differential diagnosis of CNS vasculitis is highly diverse with a broad array of mimics at the clinical, radiographic and angiographic levels.

Progressive multifocal leukoencephalopathy associated with immunosuppressive therapy in rheumatic diseases: evolving role of biologic therapies

OBJECTIVE

To evaluate the association of progressive multifocal leukoencephalopathy (PML) with immunosuppressive therapy for autoimmune rheumatic diseases (ARDs).

METHODS

A Freedom of Information Act request was submitted for all cases of PML within the Food and Drug Administration Adverse Event Reporting System database. ARD cases were selected for further analysis.

RESULTS

A total of 34 confirmed cases of PML in the setting of ARDs were identified: 17 had systemic lupus erythematosus, 10 had rheumatoid arthritis, 4 had vasculitis, and 3 had dermatomyositis. Fifteen of these patients were treated with one or more biologic agents: 14 received rituximab (RTX), 6 received anti-tumor necrosis factor (anti-TNF) therapy (5 treated with anti-TNF agent prior to RTX). Four RTX-treated patients were not receiving additional immunosuppressive therapy at the time of PML onset, other than an antimalarial drug and/or low-dose glucocorticoids; all others who were receiving a biologic agent were also receiving one or more synthetic disease-modifying agents. All but 1 patient receiving a biologic agent had at least 1 potential confounding factor for the diagnosis of PML. The remaining 19 confirmed cases of PML among ARD patients were treated with synthetic disease-modifying antirheumatic drugs only, 14 of whom had received an alkylating agent.

CONCLUSION

PML has been reported in patients with ARD treated with various immunosuppressive agents. The limitations of this study preclude definitive attribution of causality. While the paucity of confirmed cases recently exposed to anti-TNF therapy suggests a causal relationship is unlikely, a specific signal is emerging with regard to rituximab and PML. Although this is a rare adverse event associated with RTX therapy, the devastating nature of PML mandates continued vigilance, particularly in patients with current or prior exposure to an alkylating agent.

Reversible cerebral vasoconstriction syndromes: analysis of 139 cases

OBJECTIVES

To compare the clinical, laboratory, and imaging features of patients with reversible cerebral vasoconstriction syndromes evaluated at 2 academic centers, compare subgroups, and investigate treatment effects.

DESIGN

Retrospective analysis.

SETTING

Massachusetts General Hospital (n = 84) or Cleveland Clinic (n = 55).

PATIENTS

One hundred thirty-nine patients with reversible cerebral vasoconstriction syndromes.

MAIN OUTCOME MEASURES

Clinical, laboratory, and imaging features; treatment; and outcomes.

RESULTS

The mean age was 42.5 years, and 81% were women. Onset with thunderclap headache was documented in 85% and 43% developed neurological deficits. Prior migraine was documented in 40%, vasoconstrictive drug exposure in 42%, and recent pregnancy in 9%. Admission computed tomography or magnetic resonance imaging was normal in 55%; however, 81% ultimately developed brain lesions including infarcts (39%), convexity subarachnoid hemorrhage (34%), lobar hemorrhage (20%), and brain edema (38%). Cerebral angiographic abnormalities typically normalized within 2 months. Nearly 90% had good clinical outcome; 9% developed severe deficits; and 2% died. In the combined cohort, calcium channel blocker therapy and symptomatic therapy alone showed no significant effect on outcome; however, glucocorticoid therapy showed a trend for poor outcome (P = .08). Subgroup comparisons based on prior headache status and identified triggers (vasoconstrictive drugs, pregnancy, other) showed no major differences.

CONCLUSION

Patients with reversible cerebral vasoconstriction syndromes have a unique set of clinical imaging features, with no significant differences between subgroups. Prospective studies are warranted to determine the effects of empirical treatment with calcium channel blockers and glucocorticoids.

Progressive multifocal leukoencephalopathy: a national estimate of frequency in systemic lupus erythematosus and other rheumatic diseases

OBJECTIVE

Progressive multifocal leukoencephalopathy (PML) is a rare, typically fatal, central nervous system demyelinating disease that results from reactivation of the JC virus, which generally occurs in immunosuppressed hosts. The aim of this study was to generate a national estimate of the frequency of PML among patients with rheumatic diseases.

METHODS

Data were obtained from the Nationwide Inpatient Sample database. This is a 20% sample of all hospital discharges, weighted to represent the entire US inpatient population. Data were analyzed for the years 1998-2005 inclusive, representing 297,797,180 hospital discharges. Cases of PML, systemic lupus erythematosus (SLE), and other rheumatic diseases were identified by diagnostic codes from the International Classification of Diseases, Ninth Revision, Clinical Modification.

RESULTS

A total of 9,675 cases of PML were identified. The majority were associated with human immunodeficiency virus (HIV; 7,934 patients [82.00%]), hematologic cancers (813 patients [8.40%]), and solid cancers (274 patients [2.83%]). Among the rheumatic diseases, 43 cases of PML (0.44%) were associated with SLE, 24 (0.25%) with rheumatoid arthritis (RA), and 25 (0.26%) with other connective tissue diseases (CTDs). When patients with other potential risk factors for PML (HIV, malignancy, bone marrow or other organ transplantation) were excluded, the rates of PML per 100,000 discharges coded for SLE, RA, and other CTDs were 4, 0.4 and 2, respectively, compared with a rate of PML in the background population of 0.2/100,000 discharges.

CONCLUSION

This study was confined to hospitalized patients with rheumatic diseases, and it was also limited by the lack of information regarding immunosuppressive therapy. Nevertheless, the findings suggest that, although rare overall, PML occurs more commonly in SLE than in other rheumatic diseases.

Progressive multifocal leucoencephalopathy in the rheumatic diseases: assessing the risks of biological immunosuppressive therapies

Progressive multifocal leucoencephalopathy (PML) is a rare and often fatal opportunistic infection that has been well reported in patients with rheumatic diseases. The contributions of predisposing factors such as underlying disease and immunosuppressive drug selection are incompletely understood but it would appear that patients with systemic lupus erythematosus may be at highest risk. Natalizumab, a biological agent approved for multiple sclerosis and Crohn's disease has the clearest pattern of small but definite risk. Although the risk due to rituximab is difficult to assess given the multiple confounders, continued vigilance is warranted. Rheumatologists need to become familiar with PML and feel able to help patients make shared and informed decisions about the risks when starting treatment with immunosuppressive therapies. In particular, rheumatologists need to be vigilant and pursue the diagnosis of PML in all patients with unexplained neurological signs or symptoms with clinical and MRI findings compatible with the diagnosis.

Arteriovenous malformation of the brain mimicking primary central nervous system vasculitis

In the diagnosis of primary central nervous system (CNS) vasculitis, it is crucial to rule out clinical, angiographic, and pathological mimics. We report a case of arteriovenous malformation (AVM) mimicking primary CNS vasculitis. A young male presented with intracerebral haemorrhage and no other clinical, laboratory, or angiographic features suggesting vasculitis. Cerebral biopsy showed perivascular inflammation and slight infiltration of the muscular layer of cerebral vessels by chronic inflammatory cells close to the haemorrhagic areas. These findings led to a diagnosis of CNS vasculitis. The patient was initially treated with corticosteroids, but 10 months after the discovery and surgical repair of the AVM, the patient is not receiving any immunosuppressant and has not developed any features of cerebral or systemic vasculitis.