Serologic and immunopathologic findings in temporal arteritis

Ischemic optic neuropathies and their models: disease comparisons, model strengths and weaknesses

Ischemic optic neuropathies (IONs) describe a group of diseases that specifically target the optic nerve and result in sudden vision loss. These include nonarteritic and arteritic anterior ischemic optic neuropathy (NAION and AAION) and posterior ischemic optic neuropathy (NPION, APION). Until recently, little was known of the mechanisms involved in ION damage, due to a lack of information about the mechanisms associated with these diseases. This review discusses the new models that closely mimic these diseases (rodent NAION, primate NAION, rodent PION). These models have enabled closer dissection of the mechanisms involved with the pathophysiology of these disorders and enable identification of relevant mechanisms and potential pathways for effective therapeutic intervention. Descriptions of the different models are included, and comparisons between the models, their relative similarities with the clinical disease, as well as differences are discussed.

Giant cell (temporal) arteritis: an overview and update

Giant cell arteritis is a systemic disease that continues to be a sight-threatening medical emergency requiring prompt recognition and treatment in order to avoid devastating ophthalmic consequences. Although there have been advances in the genetic and immunologic understanding of the underlying pathogenesis of the disease, the exact etiology of the condition, to date, remains unclear. Visual manifestations of giant cell arteritis are the common mode of presentation, making the ophthalmologist critically responsible for early diagnosis and treatment. Although temporal artery biopsy remains the only confirmatory procedure, newer laboratory investigations and blood flow studies with fundus fluorescein angiography have aided in the diagnosis of temporal giant cell arteritis. Maintenance of a high index of clinical suspicion is essential to institute prompt adequate treatment, especially in atypical cases. Corticosteroids remain the mainstay of treatment of giant cell arteritis. Recently, immunosuppressive agents as secondary steroid-sparing drugs have been used, particularly in some steroid-resistant cases. A wider recognition of the disease will minimize the prevalence of irreversible visual loss among patients with giant cell arteritis.

Current concepts in giant cell (temporal) arteritis

Giant cell (temporal) arteritis continues to be a sight-threatening, systemic vasculitis with a poorly understood pathogenesis. The characteristic granulomatous inflammation of the vessel wall commonly leads to local ischemia. Recent advances in immunological investigations have characterized the cellular components of the disease process, but the etiology has so far remained unresolved. A reappraisal of the clinical features of giant cell (temporal) arteritis demonstrates the heterogeneity of the manifestations of the disease, including ischemic optic neuropathy. A range of new laboratory investigations and blood flow studies with color Doppler imaging have demonstrated promising roles, with respect to diagnosis and long-term follow-up. Prompt diagnosis and expeditious treatment require a high index of clinical suspicion, particularly for atypical cases. Corticosteroids remain the treatment of choice, other immuno-suppressive agents being used as second line steroid-sparing agents. Giant cell (temporal) arteritis leads to increased vascular and visual morbidity and, if untreated, may prove fatal. To maintain high standards of management of this enigmatic disorder, ophthalmologists need to be aware of the clinical spectrum of giant cell (temporal) arteritis and currently available diagnostic tests and treatment strategies.

[Immunohistochemical study of lesions in Horton's temporal arteritis before and during corticotherapy]

The immunohistochemical study was performed on temporal artery biopsies from eight patients with giant cell (temporal) arteritis: three before treatment, four after a short period of corticosteroid therapy (from 1 day to 7 days) and one during relapse occurring after a treatment of 9 years; from four subjects with clinical symptoms but without histological features of giant cell arteritis and from five negative controls. Before treatment, biopsies of patients with temporal arteritis showed an inflammatory infiltrate with macrophages and T cells, essentially CD4+ and memory T cells (CD45 RO+), expressing the markers of activation IL2 receptor and HLA DR. Few B and NK cells were also detected. Adhesion molecules, LFA1 and I-CAM1, were strongly expressed by T cells and macrophages. In contrast, the ligand to the CD2, the CD58 marker, was rarely detected. These immunohistochemical features were also observed after a short corticosteroid treatment (by intravenous methylprednisolone or oral prednisone), with presence of activated T cells, memory T cells, macrophages and I-CAM1 and LFA1 expressing cells in the infiltrate. A temporal biopsy, performed after a long time of corticosteroid therapy, showed activated T cells, macrophages and memory cells in o,ne arteriole. In controls, this study showed some mononuclear cells dispersed in intima and adventia, but without activated or memory T cells. Our results support the presence of immune local response in temporal arteritis, incompletely improved by a short corticosteroid treatment.

Clinical and laboratory findings with giant cell arteritis

Out of 66 patients who were diagnosed as suffering from polymyalgia rheumatica (PMR; n = 40), temporal arteritis (AT; n = 14) or both (n = 12) in a 6.5 year period (incidence 3.4/100,000 per year), 9 died and 49 were followed up for an average period of 28 months. Exacerbations of the illness (n = 24) and complications in the course (n = 32) were more frequent with an initial ESR greater than 90 mm/h. Postural vertigo (n = 11), amaurosis fugax (n = 11) and polyneuropathy (n = 8) were the most frequent neurological complications. Persisting unilateral blindness and aromatic anosmia developed in 2 patients each. Complications were significantly more frequent in patients with initial symptoms of AT (chi 2 P less than 0.001). CRP-levels correlated better with persisting symptoms in the course than did the ESR. Recurrences after treatment were significantly more frequent when the length of corticosteroid-therapy was less than 20 months (chi 2 P less than 0.009). On follow up there were normal values for neopterin, tumour necrosis factor and antibodies against Borrelia burgdorferi.

Immunological studies in giant cell arteritis

The results of investigations on the humoral immunological mechanisms are conflicting in giant cell arteritis (GCA) and have not been able to explain the pathological findings in the inflamed arterial wall. Altogether, immunological studies suggest that a cell-mediated immune reaction, possibly against an autologous antigen, occurs locally in the arteritic lesions of GCA. The excellent effect of treatment with glucocorticosteroids on the inflammation in GCA can also be explained by this model. The glucocorticosteroids inhibit the synthesis of interleukin-1 (IL-1) by the macrophages and suppress the IL-2 production from the T cells (Palacios, 1982). The observed HLA-DR expression in the arterial wall can be accounted for by the sum of macrophages and activated T cells, the macrophages being the most probable antigen-presenting cells. The interdigitating reticulum cells observed in some of the GCA patients may also be involved in antigen presentation. What the antigen(s) may be is, however, still unknown, as are the factors initiating the inflammatory process. It has recently been possible to extract T lymphocytes from the inflamed tissue and to culture these cells in vitro. After culture, it is possible to study the gene for the T-cell receptor, and probably even the antigenic specificity of the T cells. I hope that this approach may lead to a better understanding of the pathogenic mechanisms in GCA.

Surgical pathology of cranial arteritis and polymyalgia rheumatica

In both clinical and histological terms cranial arteritis is one of the most distinctive of all vascular disorders. The dense granulomatous inflammatory infiltrates which characterize the acute stages of the disease resemble those of Takayasu's arteritis or granulomatous angiitis of the central nervous system, but the clinicopathological features in patients with positive temporal artery biopsies are diagnostic. Well over a third of patients with classical signs and symptoms of cranial arteritis have negative temporal artery biopsies, and focal involvement of arteries of the head and neck is the probable explanation for this. Pathologists should be aware of the wide spectrum of histological changes that occur in muscular arteries as part of normal ageing and must not interpret these as evidence of healed arteritis. The histological changes of healed arteritis include medial chronic inflammation with ingrowth of new blood vessels, focal medial scarring and a bizarre pattern of intimal fibrosis. Although ultrastructural and immunohistochemical studies have provided some insight into the underlying pathological changes, they have not contributed directly to the diagnosis of cranial arteritis. Between 15 and 55% of patients with polymyalgia rheumatica have positive temporal artery biopsies, but apart from an elevated ESR there are no other laboratory investigations or biopsy procedures that contribute to diagnosis.

Generalized granuloma annulare in a patient with temporal arteritis--are these conditions associated?

A case of generalized granuloma annulare associated with temporal arteritis is described. The patient, a 79-year-old man, noticed numerous asymptomatic lesions on his trunk and extremities for 3 months. Four months later, he suffered from headache and loss of vision. Both were successfully treated by oral administration of prednisolone.

Vascular protein deposits in temporal arteritis with special reference to failure of histological findings

The object of an immunohistochemical search for vascular protein deposits in temporal arteritis is to assess the diagnostic possibilities in cases which are clinically typical but unconfirmed by biopsy results. In a group of older patients with arteritis, however, vascular aging may give rise to intimal thickening and a broad-spectrum deposition of protein. In an inter- and intra-individual comparison of vascular segments with and without arteritis we, however, found a few protein markers in arteritis which are essentially different from those in vascular aging. The intimal thickening and immune reaction in 9 selected marker proteins were graded 0-2, using the tunica media as reference for both properties. Of the nine proteins studied, alpha-2-macroglobulin was significantly increased, not only in segments affected with arteritis, but also in unaffected segments from the same biopsy as compared with biopsies from patients not suffering from this disease. 79% of patients with biopsy-confirmed arteritis also showed a significantly elevated serum alpha-2-macroglobulin as compared to 27% of those having only changes attributed to aging. In conclusion, immunohistochemical demonstration of deposits in the arterial wall and elevated serum levels of alpha-2-macroglobulin substantiate the clinical suspicion of arteritis in the absence of histological and inflammatory changes.

Temporal artery biopsies. Correlation of light microscopy and immunofluorescence microscopy

Immunopathologic studies are done routinely on biopsy specimens from tissues affected by many autoimmune diseases. To evaluate the role of direct immunofluorescence microscopy (DIFM) in identifying temporal arteritis, the authors reviewed all temporal artery biopsies done over a 30-month period (100 consecutive biopsies). The DIFM, using antibodies to IgG, IgM, IgA, complement, and fibrinogen, had a diagnostic sensitivity rate of 93% and a specificity rate of 87% compared with light microscopy. In biopsy specimens showing arteritis by light microscopy, IgG was demonstrated by DIFM in 85% of cases, IgM in 69%, and IgA in 15%. In one patient, a DIFM staining pattern highly suspicious of temporal arteritis identified a patient with features of clinical temporal arteritis despite negative findings by light microscopy. The demonstration of immunoglobulin by DIFM supports the possible role of humoral immunity in the pathogenesis of temporal arteritis.

T cell subsets and expression of immunological activation markers in the arterial walls of patients with giant cell arteritis

Immunohistochemical features of infiltrating mononuclear cells (MNC) and resident cells were studied in the temporal artery biopsy specimens of 13 patients with histological verified giant cell arteritis (GCA) and in six biopsy specimens from patients with GCA with negative histological findings. Eight temporal artery biopsy specimens from seven patients with unrelated diseases served as controls. In all patients with GCA proved by biopsy an infiltration of T lymphocytes in the arterial wall was observed, most being of the helper/inducer subset. No B lymphocytes, or very few, were seen. Lymphocytes in 10 out of the 13 positive biopsy specimens displayed staining for the class II major histocompatibility complex (MHC) antigen HLA-DR, whereas this was found in only two of eight controls. A minor number of the infiltrating T lymphocytes from seven out of 13 patients with GCA proved by biopsy stained for transferrin receptors, and in six out of the 13 cases they reacted with anti-interleukin 2 receptor antibody. In the arterial wall from all patients with histologically verified GCA we also found an increased number of macrophages, many of them expressing HLA-DR antigens and transferrin receptors. The immunohistochemical pattern of cell phenotypes found in the arterial wall of patients with GCA suggests that the infiltrating T cells are immunologically activated. This finding supports the hypothesis of a predominantly cellular immunological pathogenesis of giant cell arteritis.

Cyclophosphamide in the treatment of orbital vasculitis

When vasculitis, an angiocentric and angiodestructive process, occurs in the orbit, the clinical presentation and radiographic findings resemble those of idiopathic inflammatory pseudotumor. Three patients, two men and a woman, 28 to 72 years old, initially thought to have "pseudotumor" failed to response to corticosteroid therapy. Orbital biopsy specimens in all patients disclosed vasculitis. There was no evidence of systemic vasculitis. High-dose prednisone effectively eliminated pain and reduced inflammation but did not adequately control fibrosis formation leading to ultimate loss of function. Each patient eventually lost an eye to this process. Therapy with cyclophosphamide, a B-cell cytotoxic drug, produced a prompt response in terms of eliminating pain, inflammation, and formation of fibrous tissue. Cyclophosphamide therapy has been instrumental in preserving sight in each patient's remaining eye. In such cases we believe the benefits of cyclophosphamide therapy outweight the known risks.

Polymyalgia rheumatica and temporal arteritis

Polymyalgia rheumatica and temporal arteritis are a clinical syndrome and clinicopathologic entity, respectively. Polymyalgia rheumatica occurs more commonly than temporal arteritis, with approximately half of all patients with temporal arteritis having the polymyalgia rheumatica syndrome. Both conditions are found in the population over 50 years of age and are associated with an elevated ESR. The etiology of both is unclear, although genetic, and potentially, environmental factors may play significant roles. Both conditions respond to corticosteroid therapy, but patients with temporal arteritis require significantly higher doses to control symptoms and to prevent blindness.

B- and T-lymphocytes in ocular disease

Ocular inflammatory diseases and ocular adnexal lymphoid tumors have become less obscure and intimidating by virtue of our ability to study the infiltrates in these various diseases for their B-lymphocyte and T-lymphocyte composition. Comparisons are also possible between lymphocytic profiles in the peripheral blood and the precise composition of the in situ infiltrates within the ocular tissue themselves. The availability of monoclonal antibodies, which can determine T-lymphocytic subsets such as T-helper cells and T-suppressor/cytotoxic cells, natural killer cells, and monocytes-histiocytes, has provided a powerful technology for the delineation of the distinctive immune composition of the inflammatory infiltrates, as well as any possible disturbances in T-cell immunoregulation. B-lymphocytes produce immunoglobulins, which may be misdirected as autoantibodies in local or systemic autoimmune diseases. Immunoglobulin-mediated and therefore B-cell derived conditions include vasculitis, progressive cicatricial ocular pemphigoid, Mooren's corneal ulcer, scleritis, and hay fever and vernal conjunctivitis. Other diseases in which B-lymphocytes, their immunoglobulin products or immune complexes formed with presently unknown antigens are potentially at fault are chronic non-specific uveitis; iridocyclitis in Behcet's syndrome; Fuch's heterochromic syndrome, ankylosing spondylitis, and Reiter's syndrome; Graves' disease; and idiopathic inflammatory orbital pseudotumor and myositis. T-cells do not produce immunoglobins, but rather secrete lymphokines or interact directly with receptors or determinants on viruses or target tissues (eg. immunosurveillance against neoplasia); it is possible that some autoimmune diseases are the result of neo-antigens on the surfaces of host tissues that have been coded for by a cryptic inciting virus. T-cell diseases include phlyctenulosis graft rejections, graft versus host disease, and possibly sympathetic ophthalmia and temporal arteritis. Natural killer cells are involved in many of the same diseases as cytotoxic T-cells, except that the former require no period of sensitization (natural immunity), whereas cytotoxic T-cells must undergo an antigen-specific blast transformation (acquired immunity of the delayed hypersensitivity type). In many diseases in which B-cell derived auto-antibodies are at fault, there may be local tissue or systemic T-cell imbalances, with a reduction in T-suppressor cells and a relative augmentation in T-helper cells, thereby facilitating production of misdirected auto-antibodies.(ABSTRACT TRUNCATED AT 400 WORDS)