Tissue targeting and disease patterns in systemic vasculitis

Relevance of the CX3CL1/fractalkine-CX3CR1 pathway in vasculitis and vasculopathy

The clinical presentation of systemic vasculitis can vary widely and include skin disorders, neuropathy, eye symptoms, and systemic inflammation. The precise molecular mechanisms underlying this syndrome are not fully understood, but the importance of a chronic imbalance of the cytokines and chemokines involved in orchestrating inflammatory responses is now recognized. In similar fashion, atherosclerosis is now recognized to be a chronic inflammatory disease in which chemokines play important roles. In the current review, we discuss the involvement of CX3CL1, which is a unique member of the chemokine family, and its receptor, CX3CR1, in the pathogenesis of these vasculopathies.

Update on vasculitis

The primary systemic vasculitides comprise a broad group of diseases identified by their clinical, histopathologic, and therapeutic characteristics. These unique entities have a broad spectrum of organ involvement and severity, which influences the approach to diagnosis and treatment. Immunosuppressive and cytotoxic agents are used to manage most vasculitic diseases. Long-term outcome is influenced by chronic sequelae from organ damage, disease relapses, and medication side effects. Further research is needed to understand these diseases and discover more efficacious yet less toxic therapeutic options. This review will focus on vasculitic syndromes more likely to be presented to an allergist/immunologist in an outpatient setting.

Single-organ vasculitis

PURPOSE OF REVIEW

To provide a critical analysis of a rare disorder, single-organ vasculitis, emphasizing those organs in which the excision of the vasculitic lesion can be curative. To recommend a rational approach to diagnosis, longitudinal follow-up and treatment.

RECENT FINDINGS

Patients with focal single-organ vasculitis affecting abdominal and genitourinary organs, breast and aorta have been reported as individual cases and small series. Single-organ vasculitis differs from systemic forms of vasculitis in disease expression and prognosis. Occasionally, what appears to be a localized process evolves into a systemic disease. Depending on the organ affected, some clinical, serological and histopathologic features may be helpful in predicting the extent of the vasculitic process. With the exception of severe ischemic or hemorrhagic complications affecting the abdominal organs and dissection or rupture of the aortic arch, the prognosis of focal single-organ vasculitis tends to be excellent. Resection of the inflammatory lesion may be curative.

SUMMARY

The diagnosis of focal single-organ vasculitis is always presumptive and requires exclusion of systemic illness at the time of diagnosis as well as throughout the period of continued care. Clues from clinical symptoms, laboratory tests and histopathologic features at the time of diagnosis may assist in devising surveillance strategies.

Vasculitis involving the breast: a clinical and histopathologic analysis of 34 patients

Vasculitis of the breast (VB) may be an isolated finding or a manifestation of systemic vasculitis. In the current study we sought to characterize isolated VB (IVB) and compare it to VB in the setting of systemic vasculitis. We studied VB cases in the literature and patients cared for at our institution. We analyzed clinical, laboratory, and histologic features (including vessel size and type of inflammatory infiltrates); course of illness; biopsy procedure; and treatment. Based on the presence of localized or systemic disease at the time of disease presentation and during the follow-up, we divided patients into 3 groups: IVB (Group 1), VB with proven or indirect evidence of systemic vasculitis (Group 2), and VB with possible systemic involvement (Group 3). We identified a total of 34 cases of VB (30 from PubMed [National Library of Medicine, Bethesda, MD] and 4 from our pathology database). All patients presented with breast lesions, which were the only expression of disease in 16 (47%). Eighteen, 6, and 10 patients belonged to Group 1, 2, and 3, respectively. Constitutional symptoms were present less often in Group 1. Musculoskeletal symptoms occurred only in Groups 2 and 3. Patients in Groups 2 and 3 had higher erythrocyte sedimentation rates and lower hemoglobin levels, and also received corticosteroids more frequently than those in Group 1. No differences were found in the other analyzed parameters between groups. In summary, VB is uncommon, and in about half of the cases, occurs in the form of IVB. Histologic characteristics do not correlate with disease extent. In IVB patients, constitutional and musculoskeletal manifestations are usually absent. Such patients generally do not require systemic therapy and may be cured by resection alone.

Transient encephalopathy complicating poststreptococcal glomerulonephritis in an adult with diagnostic findings consistent with cerebral vasculitis

We report the case of a young woman who had transient encephalopathy with nausea, cognitive impairment, 2 generalized seizures accompanied by visual impairment, and stenotic alterations of cerebral vessels lasting for weeks until complete resolution. These findings were associated with an elevated antideoxyribonuclease B level and biopsy-proven poststreptococcal glomerulonephritis. At the time of the encephalopathy, the patient had no electrolyte level disturbances, an only mildly elevated urea level, and moderate arterial hypertension and was on methylprednisolone therapy. For a couple of days, cranial magnetic resonance imaging showed multiple disseminated asymmetric hyperintensities on T(2)-weighted and fluid-attenuated inversion recovery, suggesting vasogenic edema. However, Doppler ultrasound examinations showed stenoses of extracerebral and multiple intracerebral arteries that persisted for several weeks, lasting considerably longer than the cerebral edema. This finding does not fit the context of hypertensive or steroid-induced encephalopathy, but is consistent with diagnosis of an accompanying vasculitis. Treatment with methylprednisolone for several weeks was associated with resolution of arterial stenoses and neurological symptoms, complete reversibility of Doppler sonographic findings, and significant improvement in renal function.

Endothelial cells, antineutrophil cytoplasmic antibodies, and cytokines in the pathogenesis of systemic vasculitis

Endothelial cells play a pivotal role in the pathogenesis of systemic vasculitis. Endothelial cells have significant proinflammatory activities, amplifying and perpetuating the inflammatory process and contributing to vessel regeneration and repair. Significant contributions have improved the understanding of additional ways through which antineutrophil cytoplasmic antibodies (ANCA) may potentiate neutrophil- and monocyte-mediated endothelial cell activation and damage. Signaling pathways mediating ANCA effects have been delineated, and new animal models have demonstrated the pathogenic role of ANCA in the development of systemic vasculitis. Significant efforts have identified anti-endothelial cell antibody specificities and elucidated mechanisms through which these antibodies may promote endothelial cell activation and injury. New ways to assess in vivo endothelial cell damage and dysfunction also have been developed. In addition, besides being a relevant compensatory mechanism for ischemia, angiogenesis may have important proinflammatory functions in vasculitis. The potential relevance of bone-marrow-derived endothelial cell precursors in neovascularization has begun to be appreciated.