HLA-B27 transgenic rats model

To investigate the role of HLA-B27 in the pathogenesis of spondylarthropathies, rats transgenic for HLA-B27 and human beta 2-microglobulin were produced. Several lines of B27 transgenic rats spontaneously develop a multisystem inflammatory disorder reminiscent of human spondylarthropathies, with gut, joint, skin and male genital lesions. The role of HLA-B27 in this model was studied and it was found that a high expression level of the transgene in cells of hematopoietic origin was critical to induce inflammatory manifestations. Furthermore, a combined implication of CD4+ T cells and antigen presenting cells in this model is suspected, based on passive transfer studies, although a specific influence of HLA-B27 upon T cell education in the thymus is unlikely to be important. Beside the immune system, bacterial flora exerts an important influence in this model, as a triggering agent of gut and joint inflammation. Finally, endogenous rat genetic factors are suspected to be involved in this model.     

HLA-B27 associated spondyloarthropathy and severe ascending aortitis

We describe a young woman who developed early and severe aortic regurgitation and subsequent aortitis with aneurysm formation requiring surgery.     

Psoriatic spondyloarthropathy: a comparative study between HLA-B27 positive and HLA-B27 negative disease

OBJECTIVES: To evaluate the relative contribution of the human leukocyte antigen (HLA)-B27 to psoriatic spondyloarthropathy (PsSpA) susceptibility and to analyze whether this antigen contributes to disease expression. METHODS: This cross-sectional study included 70 patients (mean age 48 +/- 14.5 years; 44 men and 26 women). PsSpA was defined according to radiological findings (grade 2 or more sacroiliitis), and patients were classified into 3 main subtypes: isolated axial disease (n = 16), axial plus oligoarthritis (n = 29) and axial plus polyarthritis (n = 25). All patients were studied following a standard protocol that included the collection of demographic and epidemiological data, clinical history, radiographs, complementary tests, physical examination, and HLA-B27 testing (serological method). For functional evaluation, the Health Assessment Questionnaire-Specific for spondyloarthropathy (HAQ-S) was used. Patients with and without HLA-B27 antigen were compared on the basis of the data. RESULTS: Twenty-four patients (34%) carried the HLA-B27 antigen (RR 6.4, P <.0004). Fifty-six percent of those patients with the isolated axial pattern had this antigen, compared with 24% in the poly-arthritis axial pattern and 31% of those in the oligo-arthritis axial group (P =.016). Univariate analysis demonstrated correlations between HLA-B27 and an earlier age of onset for both psoriasis (P =.028) and arthritis (P =.006), male gender (P =.002), bilateral sacroiliitis (P =.002), and uveitis (P =.026). HLA-B27 negative patients developed more peripheral erosions than HLA-B27 positive patients (P =.05). No correlation was found between B27 and clinical symptoms of back involvement, syndesmophytes, or functional impairment. CONCLUSIONS: The HLA-B27 antigen is not only important for PsSpA susceptibility, but also determines some clinical features. This antigen was associated with earlier age of psoriasis and arthritis onset, bilateral sacroiliitis, and male gender. However, it was not associated with either the severity or extension of the spondylitic process or with functional impairment.     

HLA-B27 associated spondyloarthropathy, an autoimmune disease based on crossreactivity between bacteria and HLA-B27?

Most autoimmune diseases are associated with certain HLA types. Therefore, spondyloarthropathies (SpA) strongly associated with HLA-B27, are also often classified as autoimmune diseases. This study questions whether SpA indeed fulfils the criteria of an autoimmune disease. The Medline database was searched for all reports between 1966 and April 1998 on the presence of autoimmune reactivity in SpA patients. This search yielded 45 articles on this subject. Only eight articles study T cell reactivity. Twelve reports were found on the assessment of antibodies crossreacting between bacteria and HLA-B27. In the 45 studies demonstrating autoimmune reactions in SpA patients proper controls matched for HLA-B27, sex and age were nearly always lacking. Therefore, it is concluded that the frequency of increased autoreactivity in sera from patients and controls is not significantly different, and that this lack of autoreactivity does not justify classification of SpA as an autoimmune disease. As crossreactive antibodies against bacteria and HLA-B27 were equally present in sera from patients and controls, the pathogenetic significance of molecular mimicry between various bacteria and HLA-B27 is questionable. Furthermore, the regions of the B27 molecule that are supposed to be crossreactive with bacteria, differ in one or more amino acids among the distinct B27 subtypes. Although these differences strongly influence the binding of antibodies to the B27 molecule, there was no relation between the degree of crossreactivity of certain subtypes and the association of these subtypes with SpA. In conclusion, there is no evident proof that SpA is an autoimmune disease attributable to crossreactivity between bacteria and HLA-B27.     

Beta 2-microglobulin amyloid deposit in HLA-B27 transgenic rats

Beta 2-microglobulin (beta 2-m) amyloid deposition develops serious orthopedic complications in patients with long-term hemodialysis. However, the exact pathogenesis of amyloid deposition in patients with dialysis is unknown. We used transgenic rats with HLA-B27 and beta 2-m to develop an in vivo animal model with beta 2-m amyloid-associated disorders to investigate the mechanism of formation and to report histological findings of beta 2-m amyloid deposition. Transgenic rats were divided into two groups: group 1, no treatment; group 2, arthritis induced by type II collagen. A large number of cells labeled with beta 2-m were observed in the bone marrow and synovium of the knee joint in transgenic rats. In addition, amyloid deposition, identified by Congo red staining, was found only in the knee joints of the transgenic rats with collagen-induced arthritis. Immunostaining with beta 2-m demonstrated the same pattern of tissue distribution as Congo red in serial sections. We hypothesized that elevated serum beta 2-m level-associated local chronic inflammation leads to the development of amyloid deposits and resultant arthropathy.     

Beta 2-microglobulin amyloid deposit in HLA-B27 transgenic rats

Abstract

Beta 2-microglobulin (beta 2-m) amyloid deposition develops serious orthopedic complications in patients with long-term hemodialysis. However, the exact pathogenesis of amyloid deposition in patients with dialysis is unknown. We used transgenic rats with HLA-B27 and beta 2-m to develop an in vivo animal model with beta 2-m amyloid-associated disorders to investigate the mechanism of formation and to report histological findings of beta 2-m amyloid deposition. Transgenic rats were divided into two groups: group 1, no treatment; group 2, arthritis induced by type II collagen. A large number of cells labeled with beta 2-m were observed in the bone marrow and synovium of the knee joint in transgenic rats. In addition, amyloid deposition, identified by Congo red staining, was found only in the knee joints of the transgenic rats with collagen-induced arthritis. Immunostaining with beta 2-m demonstrated the same pattern of tissue distribution as Congo red in serial sections. We hypothesized that elevated serum beta 2-m level-associated local chronic inflammation leads to the development of amyloid deposits and resultant arthropathy.     

HLA-B27 associated spondyloarthropathy, vasculitis, and amyloid enteropathy: response to infliximab

In 2000 we described a patient with HLA-B27 associated spondyloarthropathy (SpA) and severe ascending aortitis requiring surgical intervention. Despite continued immunosuppressive therapy she developed narrowing of the distal part of the right subclavian artery and proximal axillary artery secondary to active vasculitis. In addition, biopsy-proven amyloid gastroenteropathy developed causing persistent diarrhea and iron deficiency anemia. Treatment with infliximab resulted in resolution of joint symptoms and rapid improvement in laboratory markers of inflammation. Diarrhea settled more gradually, such that her bowel habit had normalized 16 months after therapy commenced.     

Lactobacillus GG prevents recurrence of colitis in HLA-B27 transgenic rats after antibiotic treatment

BACKGROUND AND AIMS: Bacteroides vulgatus induces colitis in gnotobiotic HLA-B27 transgenic (TG) rats while broad spectrum antibiotics prevent and treat colitis in specific pathogen free (SPF) TG rats although disease recurs after treatment ends. Lactobacilli treat human pouchitis and experimental colitis. We investigated if Lactobacillus rhamnosus GG (L GG) can prevent colitis in TG rats monoassociated with B vulgatus and if L GG or Lactobacillus plantarum 299v (LP 299v) can treat established colitis in SPF TG rats and prevent recurrent disease after antibiotics were stopped. METHODS: Germfree B27 TG rats were monoassociated with B vulgatus for four weeks following two weeks of colonisation with L GG or no bacteria. SPF B27 TG rats received oral vancomycin and imipenem for two weeks, or water alone, followed by four weeks of treatment with oral L GG, LP 299v, or water only. Disease activity was quantified by blinded gross and histological scores, caecal myeloperoxidase (MPO) activity, and levels of interleukin (IL)-1 beta, tumour necrosis factor (TNF), transforming growth factor beta, and IL-10. RESULTS: L GG did not prevent colitis in B vulgatus co-associated TG rats or treat established disease in SPF rats. However, L GG but not LP 299v prevented colitis relapse in antibiotic treated rats with reduced gross and histological scores, caecal MPO, IL-1 beta, and TNF whereas caecal IL-10 was increased. CONCLUSIONS: L GG does not prevent colitis in gnotobiotic TG rats or treat established disease in SPF rats, but is superior to LP 299v in the prevention of recurrent colitis. These studies suggest that antibiotics and probiotic agents provide synergistic therapeutic effects, perhaps mediated by altered immunomodulation with selective activity of different lactobacillus species.     

Maternal age influences risk for HLA-B27 associated ankylosing enthesopathy in transgenic mice.

OBJECTIVE--To study further the temporal clustering of ankylosing enthesopathy (AE) noted originally during a study of the influence of mouse major histocompatibility complex (MHC) H-2 and transgenic HLA-B27 on the frequency of AE. METHODS--The relationship between maternal age at littering and frequency of AE was analysed. RESULTS--Mice born to mothers aged eight months or older had a significantly lower disease frequency of AE than mice born to mothers younger than eight months of age. This phenomenon was observed in three independent cohorts evaluated to date (p < 0.01, 0.025, and 0.05). CONCLUSION--Maternal age is a novel, non-genetic risk factor as defined in relation to an MHC associated enthesopathy. Its mode of action and relevance to human disease require further investigation.     

Familial aggregation of undifferentiated spondyloarthropathy associated with HLA-B7.

OBJECTIVE--To report multiple cases of recurrent seronegative arthropathy, enthesopathy, or both, occurring in a single family in the absence of the HLA-B27 tissue type, coexistent psoriasis or inflammatory bowel disease. METHODS--Three generations of one family together with their general practitioners completed a standard questionnaire. All subjects with a positive questionnaire and two randomly chosen subjects with negative questionnaires were then examined by a single observer. HLA tissue typing and standard sacroiliac radiographs were performed. RESULTS--Seven of 12 family members with a positive questionnaire had early onset oligo- or polyarthritis, enthesitis, or both, and fulfilled established criteria for spondyloarthropathy, although none had radiological evidence of sacroiliitis. The mean age at first symptom in this group was 22 years with only one individual having the first symptom over the age of 30 years. All subjects were rheumatoid factor negative. Histocompatibility studies showed a strong association with the HLA-B7 antigen. CONCLUSIONS--The observations provide further support for the existence of 'undifferentiated' spondyloarthropathy and suggest that this can be associated with genetic factors other than HLA-B27.     

Evidence of subclinical intestinal inflammation by 99m technetium leukocyte scintigraphy in patients with HLA-B27 positive juvenile onset active spondyloarthropathy

OBJECTIVE: The concept that gut inflammation is implicated in the pathogenesis of spondyloarthropathies (SpA) has long been considered. Subclinical intestinal inflammation has been reported in adult patients with SpA by histological examination of intestinal biopsies. We assessed the presence of gut inflammation by abdominal 99mTc-hexamethyl propylene amine oxime (99mTc-HMPAO) labeled leukocyte scintigraphy in a group of children and adolescents with HLA-B27 positive SpA without gastrointestinal (GI) symptoms, and correlated the scintigraphic results to disease activity. METHODS: Abdominal scintigraphy with 99mTc-HMPAO labeled leukocytes was performed in 27 HLA-B27 positive children and adolescents with SpA without GI symptoms. Patients were divided into 2 groups according to the presence of active or inactive joint disease: Group A, 17 patients with active disease, and Group B, 10 patients with inactive disease. Patients with positive abdominal scintigraphy underwent complete bowel investigation by means of small bowel barium follow-through, abdominal ultrasound scan, and ileocolonoscopy with mucosal biopsies. RESULTS: Thirteen of 27 patients (48%) had scintigraphy indicating the presence of bowel inflammation. All patients with abnormal scan had active joint disease, whereas no patient with inactive disease had a positive intestinal uptake of labeled leukocytes. Bowel investigation revealed the presence of aspecific mucosal inflammatory changes in the majority of patients with positive scintigraphy. CONCLUSION: The presence of intestinal leukocyte uptake only in patients with active joint disease, even if intestinal inflammatory changes were minimal and clinical gut manifestations were absent, supports the role of gut inflammation in the pathogenesis of joint disease in HLA-B27 positive patients with SpA.     

Defective costimulatory function is a striking feature of antigen-presenting cells in an HLA-B27-transgenic rat model of spondylarthropathy

OBJECTIVE: A disease resembling the human spondylarthropathies develops in HLA-B27-transgenic rats. This disease in rats is mediated by CD4+ T cells, but antigen-presenting cells (APCs) may also play a role. Dendritic cells (DCs) have been reported to be defective in allogeneic mixed lymphocyte culture in this model. Here, we further investigated the functional defect of APCs. METHODS: DCs and B cells from nontransgenic, HLA-B27 (33-3)-transgenic, and HLA-B7 (120-4)-transgenic rats were used to stimulate T cells. Surface expression of HLA-B transgene and rat molecules on APCs and the formation of conjugates between DCs and T cells were monitored by flow cytometry. RESULTS: We observed a strikingly defective stimulation of allogeneic and syngeneic T lymphocytes by APCs from HLA-B27 but not HLA-B7 rats, even if stimulation was driven in the presence of anti-T cell receptor (TCR) antibody. We found no evidence that HLA-B27 DCs were immature, lacked production of some diffusible factor, or produced an inhibitory factor for T cells. When comparing the levels of expression of class II major histocompatibility complex, CD2, intercellular adhesion molecule 1, lymphocyte function-associated antigen 1, B7, and CD40 molecules at the surface of DCs from 33-3, 120-4, and nontransgenic rats, we found little difference. However, HLA-B27-transgenic DCs formed fewer conjugates with T cells than did nontransgenic DCs. Furthermore, the proportion of conjugates formed between DCs and T cells, as well as the difference between nontransgenic and HLA-B27-transgenic DCs, were in large part reduced by blocking CD86 on DCs. CONCLUSION: We confirmed defective stimulation of T cells by APCs in HLA-B27 rats, the mechanism of which appears to implicate APC/T cell contact, independent of TCR engagement. In addition, decreased use of the CD86 costimulatory molecule by B27 DCs was observed. Impaired costimulatory function could result in a loss of tolerance toward microbial flora in this model.     

A hypothesis for the HLA-B27 immune dysregulation in spondyloarthropathy: contributions from enteric organisms, B27 structure, peptides bound by B27, and convergent evolution.

Several human rheumatic diseases occur predominantly in persons who carry the histocompatibility (HLA) class I allele B27. They have also been related to Gram-negative enteric microorganisms. In addition, the recent recovery of peptides bound to B27 has allowed an understanding of the structural requirements for their binding. Using the accumulated data base of protein sequences, we have tested a series of hypotheses. First, we have asked whether the primary amino acid sequence of the hypervariable regions of HLA-B27 shares short sequences with the proteins of Gram-negative enteric bacteria. The data demonstrate that, unique among the HLA-B molecules, the hypervariable regions of HLA-B27 unexpectedly share short peptide sequences with proteins from these bacteria. Second, we have asked whether the enteric proteins tend to satisfy the structural requirements for peptide binding to B27 in those regions of the sequence shared with B27. This hypothesis also tends to be true, especially in an allelically variable part of the B27 sequence which is predicted to bind B27 if it were to be presented as a free peptide. We conclude that HLA-B27 and enteric Gram-negative bacteria have undergone a previously unappreciated form of convergent evolution which may be important in the process leading to these rheumatic diseases. Moreover, the regions of the enteric bacterial proteins which are contiguous with the short sequences shared with B27 tend to have structures which are also predicted to bind B27. These observations suggest a mechanism for autoimmunity and lead to the prediction that the B27-associated diseases are mediated by a subset of T-cell receptors, B27, and the peptides bound by B27.