HLA-B27 and acute anterior uveitis

Molecular Genetic Advances in Uveitis

Uveitis is usually considered as an intraocular inflammation characterized by variety of clinical features. Behcet's disease (BD), Vogt-Koyanagi-Harada (VKH) syndrome, acute anterior uveitis (AAU), and birdshot chorioretinopathy (BCR) are examples of noninfectious forms of uveitis. Although the precise pathogenesis remains unclear, accumulating evidence shows that complex genetic backgrounds coupled with an aberrant immune response may be implicated in the development of uveitis. The complement and pattern recognition systems are both important factors of the innate immune system and are involved in the pathogenesis of uveitis. Copy number variants (CNVs) of complement component 4 have been found to be associated with BD and VKH syndrome, but not with AAU. Several CNVs and gene polymorphisms of toll-like receptors were found to be associated with BD. Leukocytes are an important part of the adaptive immune system and various molecules on these cells play an important role in the development of uveitis. Genes encoding for human leukocyte antigens (HLAs) have been shown to be associated with certain uveitis entities, including BD (HLA-B51), VKH syndrome (HLA-DR4, DRB1/DQA1), AAU (HLA-B27), and BCR (HLA-A29). Genome wide association studies showed that the IL-23R locus was a shared risk factor for multiple uveitis entities including BD, AAU, and VKH syndrome. In addition, various other non-HLA genes are also associated with BD or VKH syndrome, such as IL-10, STAT4, STAT3, and UBAC2. These studies support the hypothesis that genetic factors play a key role in the pathogenesis of uveitis.

Anterior uveitis investigation by Canadian ophthalmologists: insights from the Canadian National Uveitis Survey

BACKGROUND

Anterior uveitis can be the result of a number of underlying etiologies and is commonly seen in ophthalmology practice. The clinician must choose from a battery of potential investigations. A nonselective approach to testing is costly and inefficient and can lead to misinterpretation of false positive results. The purpose of this study was to identify investigation patterns of ophthalmologists in Canada for anterior uveitis and to make evidence-based recommendations for appropriate tests that could lead to improved patient care and more cost-effective use of health care resources.

METHODS

A cross-sectional survey of practicing ophthalmologists, fellows, and residents in Canada was conducted in September 2004. The survey instrument was an 11-item questionnaire mailed to 1196 physicians in Canada.

RESULTS

A total of 498 (42%) physicians responded to the survey. A wide range of tests were chosen when respondents were presented with 5 scenarios for anterior uveitis and asked what investigations they would order. Many of these tests have low diagnostic yields because they lack the sensitivity and specificity to be used as routine investigations in the setting of anterior uveitis.

INTERPRETATION

Increased education and awareness could lead to more cost-effective and efficient investigations in the setting of anterior uveitis. On the basis of evidence from a review of the literature, we make recommendations for investigations that should be considered in patients with anterior uveitis.

Posterior segment inflammation in HLA-B27+ acute anterior uveitis: clinical characteristics

PURPOSE

To examine clinical characteristics of patients who have posterior segment manifestations in HLA-B27-associated acute anterior uveitis.

METHODS

Medical records of 114 HLA-B27-positive patients with acute anterior uveitis were reviewed in a retrospective fashion. Criteria for inclusion were the presence of acute anterior uveitis, a positive HLA-B27 antigen, and one of the following findings: vitreous cells >/=+2; cystoid macular edema; papillitis; vasculitis; or pars plana exudates. Twenty-four patients met the inclusion criteria.

RESULTS

Posterior segment manifestations were found in 24 (21.05%) of 114 patients with HLA-B27+ acute anterior uveitis. Eighteen patients had diffuse vitritis (75%), seven had cystoid macular edema (29.1%), and two had papillitis (8.3%). Three patients had more than one finding. The prevalence of associated systemic disease (15 of 24 patients, 62.5%) and hypopyon (6 of 24 patients, 25%) in patients with posterior segment involvement was significantly higher than in the group of patients without posterior segment involvement (systemic disease, 33 of 90, 36.7%, p=0.04, exact chi-quare test; hypopyon, 4 of 90, 4.4%, p=0.006, exact chi-square test). The mean visual acuity at the last visit was 20/30 (range 20/20-20/100). Immunosuppressive therapy (other than corticosteroids) and surgical intervention were not required in the treatment of patients with posterior segment manifestations. CONCLUSION<?Pub Caret>: HLA-B27+ anterior uveitis is associated with posterior segment manifestations. Patients with posterior segment involvement have a significantly higher incidence of associated systemic diseases and hypopyon.

Acute anterior uveitis: clinical and experimental aspects

Acute anterior uveitis (AAU) or iritis is an inflammatory disorder of the anterior structures of the eye that may be associated with a number of disease entities. A significant proportion of patients will have no evidence of an underlying disorder and are labeled as idiopathic. Within this group approximately 50% will possess the human leukocyte antigen, HLA-B27, and some will have an associated spondyloarthropathy such as ankylosing spondylitis or Reiter's syndrome. Nevertheless, a number of HLA-B27-positive patients have no apparent underlying rheumatic disorder. The potential interplay of HLA-B27 and certain infective agents in the pathogenesis of AAU is discussed with particular reference to Yersinia species. Presentation of a uveitogenic peptide, similar to the arthritogenic peptide model in spondyloarthropathies, may be a mechanism involved in the development of AAU. Experimental models in animals have increased our understanding of the roles of retinal proteins and bacterial peptides, as well as T cells and cytokines, in the pathogenesis of uveitis. As in animal models of arthritis, certain retinal peptides (in conjunction with adjuvant therapy) can induce uveitis in animals. The treatment of isolated AAU usually involves topical medication and the prognosis is good. Occasional cases, especially those associated with systemic disorders, may require the addition of systemic corticosteroids or other immunosuppressive medications.