Activated, cytotoxic lymphocytes in systemic vasculitis

Longitudinal monitoring of circulating immune cell phenotypes in large vessel vasculitis

Giant cell arteritis (GCA) and Takayasu arteritis (TAK) are two types of primary large vessel vasculitis (LVV). LVV is an intractable, rare disease with a high relapse rate. Disease progression in asymptomatic patients is an important issue in the clinical management of LVV. Useful biomarkers associated with clinical phenotypes, disease activity, and prognosis may be present in peripheral blood. In this review, we focused on peripheral leukocyte counts, surface markers, functions, and gene expression in LVV patients. In particular, we explored longitudinal changes in circulating immune cell phenotypes during the active phase of the disease and during treatment. The numbers and phenotypes of leukocytes in the peripheral blood were different between LVV and healthy controls, GCA and TAK, LVV in active versus treatment phases, and LVV in treatment responders versus non-responders. Therefore, biomarkers obtained from peripheral blood immune cells may be useful for longitudinal monitoring of disease activity in LVV.

Sherlock Holmes in the ER (the case of red and the head)

A 58-year-old woman presented with a problem with her peripheral vision. Computed tomography scan showed an occipital hemorrhagic stroke. She subsequently suffered gastrointestinal bleeding and at surgery biopsy of a portion of the middle colic artery aneurysm revealed changes consistent with polyarteritis nodosa.

Evidence for the Involvement of CD44 in Endothelial Cell Injury and Induction of Vascular Leak Syndrome by IL-2

At sites of chronic inflammation seen during infections, autoimmunity, graft-vs-host response, and cytokine therapy, endothelial cell injury is known to occur, the exact mechanism of which is unknown. In the current study we used IL-2-induced vascular leak syndrome (VLS) as a model to investigate whether cytotoxic lymphocytes use CD44 in mediating endothelial cell injury. Administration of IL-2 to wild-type mice triggered significant VLS in the lungs and liver. In contrast, in CD44 knockout (KO) mice, IL-2-induced VLS was markedly reduced in the lungs and liver. IL-2-treated wild-type and CD44 KO mice had similar levels of perivascular infiltration with lymphocytes in the lungs and liver. This suggested that the decrease in VLS seen in CD44 KO mice was not due to the inability of lymphocytes to migrate to these organs. Ultrastructural studies demonstrated extensive endothelial cell damage in the lungs and liver of IL-2-treated wild-type, but not CD44 KO, mice. Moreover, CD44-KO mice exhibited a marked decrease in IL-2-induced lymphokine-activated killer cell activity. The induction of VLS was dependent on the expression of CD44 on immune cells rather than endothelial cells because adoptive transfer of CD44+, but not CD44− spleen cells along with IL-2 into CD44 KO mice triggered VLS. The IL-2-induced VLS was blocked by administration of F(ab′)2 of Abs against CD44. The current study demonstrates that CD44 plays a key role in endothelial cell injury. Blocking CD44 in vivo may offer a novel therapeutic approach to prevent endothelial cell injury by cytotoxic lymphocytes in a variety of clinical disease models.

Neurological manifestation of vasculitis: update on immunopathogenic mechanisms and clinical features

Study of the vasculitides illustrates a spectrum of interactions from physiological to pathological between the immune system and the blood-vessel wall. Endothelial cells demonstrably recruit leukocytes by both antigen-specific and antigen-nonspecific mechanisms in the systemic vasculitides. A cascade of cytokine and factors can initiate, perpetuate, and regulate the close interactions of leukocytes and the endothelium. Specific types of leukocytes (neutrophils, T lymphocytes, eosinophils) predominate in the vascular infiltrates of specific diseases. Other mural cells potentially initiate the inflammatory process; this may be particularly important in the central nervous system where regulatory systems may diminish a primary role of the endothelium in vascular inflammation. Neurological abnormalities are a prominent feature of some vasculitides and rare in others. In polyarteritis nodosa, Wegener's granulomatosis, and lymphomatoid granulomatosis neurological features may be prominent and early. The cutaneous vasculitides, hypersensitivity vasculitis, are seldom associated with neurological abnormalities. Isolated angiitis of the central nervous system is notable because it invariably targets the central nervous system and because it must be distinguished from other causes of central nervous system vasculitis, including infections and toxins. In this article we review some of the recent information adding to our knowledge of the immunopathogenic and clinical features in the vasculitides affecting the nervous system.