Polymorphonuclear cell motility, ankylosing spondylitis, and HLA B27

Reiter's syndrome and reactive arthritis: a current view

This paper reviews advances in the understanding of the pathogenesis of reactive arthritis that have occurred over the last decade. Inflammatory aseptic joint disease has been linked with prior infection initiated by many different species of microorganisms. The presence of intra-articular bacterial antigens has now been firmly established with the demonstration of bacteria, bacterial fragments, DNA, RNA, and bacterial lipopolysaccharide in joints of patients with reactive arthritis. Chlamydia trachomatis, Salmonella enteritidis, and Shigella flexneri have all been detected in the joint by immunological techniques, although there is still some doubt as to the form in which they reach the joint and whether or not they persist. A number of phlogistic bacterial components could be acting as arthritogens. Negative joint culture results from patients with reactive arthritis make it unlikely that bacteria in the joint are viable, although chlamydial DNA has been shown in the joints of patients with sexually acquired reactive arthritis using the polymerase chain reaction. The use of antimicrobial therapy in the treatment of reactive arthritis is under review; data suggests that long-term antibiotic treatment warrants further study. The role of HLA-B27 in disease pathogenesis is discussed as are possible mechanisms of interplay between germ and gene. HLA-B27 might confer disease susceptibility by affecting immune mechanisms other than classical antigen presentation. The immunopathogenesis of joint inflammation in reactive arthritis is explored with reference to studies of humoral and cellular immune responses. Serological evidence to support the concept of molecular mimicry is far from conclusive; the results of relevant studies are summarized. Lymphocyte proliferation experiments suggest that antigen presenting cells play an important role. Finally, our views on reactive arthritis in the 1990s, and areas of new and potentially fruitful future research are presented.

Alkali-treated LPS of Yersinia enterocolitica does not induce expression of E-selectin, ICAM-1 or VCAM-1 on endothelial cells but may mediate antibody- and complement-dependent cell injury

Lipopolysaccharide (LPS) prepared from a rough mutant of Salmonella typhimurium and deacylated enzymatically (dLPS) does not promote neutrophil adherence to human umbilical vein endothelial cells (HUVECs). This paper reports that similarly, a smooth form of LPS prepared from Yersinia enterocolitica O:3, a serotype known to trigger reactive arthritis in humans, and treated with alkali (yersinia LPS-OH) failed to augment neutrophil adherence to HUVECs. Studies of the mechanism underlying the poor augmentation revealed that neither enzymatically deacylated LPS from Escherichia coli J5 (J5 dLPS) nor yersinia LPS-OH stimulated expression of endothelial cell adhesion molecules E-selectin, VCAM-1 and ICAM-1, whereas both intact J5 LPS and yersinia LPS were stimulatory. Impaired up-regulation could not be explained by decreased binding of yersinia LPS-OH to HUVECs. Furthermore, 51Cr-labelled HUVECs treated with different concentrations of yersinia LPS-OH released 51Cr in the presence of anti-yersinia anti-O antibody and complement. J5 dLPS and yersinia LPS-OH inhibited up-regulation of the adhesion molecules induced by J5 LPS and yersinia LPS but not that induced by tumour necrosis factor alpha. Taken together, the results suggest that although yersinia LPS-OH can depress development of acute inflammation by inhibiting up-regulation of endothelial-cell adhesion molecules, sufficient LPS-OH is bound to induce cell injury and thereby inflammation in the presence of specific antibody and complement. The findings may have pathogenetic implications in yersinia-triggered reactive arthritis characterized by dissemination of yersinia LPS throughout the body.

HLA and disease

Many human diseases are associated with HLA class I, class II and class III antigens. It appears that the class III antigen disease associations can be explained by a direct defect operating at the level of either the class III gene or its gene product. The mechanism underlying class I and class II antigen disease associations is at present unknown. In this review we have considered thirty diseases which have been ranked according to their relative risk as defined by the frequency of a given HLA antigen in patient and control populations. The chronic inflammatory disorder, ankylosing spondylitis and its association with HLA B27 has been used as a model to study the HLA linked diseases. We have suggested that the disease may be caused by the Gram-negative microorganism Klebsiella which has antigenic similarity to HLA B27. It is proposed that some antibodies made against Klebsiella bind to HLA B27, thereby acting as autoantibodies leading to the pathological sequelae of chronic inflammatory arthritis. This is the crosstolerance hypothesis or molecular mimicry model and it has been compared to the receptor model. It is further suggested that the crosstolerance hypothesis can be utilised as a general theory to explain the association of other diseases with the class I and class II antigens, and offer a possible explanation for the polymorphism of HLA.

The phagocyte oxidative metabolism function in ankylosing spondylitis

The phagocyte oxydative metabolism function was measured using chemiluminescence in microamounts of whole blood in 15 ankylosing spondylitis (AS) patients (10 were B27 positive), and in 17 controls. It was obtained from cells at rest, and following stimulation (latex, zymosan, fMLP), with luminol and lucigenin as amplifiers. The maximal light intensity was significantly higher (P less than 0.01) in AS compared to the controls in resting cells as well as in those after stimulation. There was no difference between HLA-B27 positive or negative AS patients. The increase in oxidative metabolism of the phagocyte system in AS was more evident in the luminol dependent assay, suggesting an activation of the myeloperoxydase system.

Chemotaxis and chemiluminescence responses of synovial fluid polymorphonuclear leucocytes during acute reactive arthritis

The chemotaxis and chemiluminescence responses of polymorphonuclear leucocytes (PMN) of synovial fluid and peripheral blood from patients with acute reactive arthritis were studied. Rates of chemotactic and chemokinetic migration of synovial fluid PMN were significantly decreased. In addition, chemiluminescence responses tended to be depressed, suggesting that the cells were deactivated for both chemotaxis and production of oxygen derived free radicals. Such deactivation has been described previously as a characteristic of synovial fluid PMN in rheumatoid arthritis. Compared with those with a mild disease, patients with severe acute reactive arthritis had higher chemiluminescence responses of synovial fluid PMN to phorbol myristate acetate during acute disease and developed increased migration of peripheral blood PMN towards zymosan treated serum after recovery from the disease. This supports the view that hyperreactive PMN contribute to the development of severe inflammatory symptoms in acute reactive arthritis.

Inflammation in HLA-B27-associated diseases

The pathogenetic mechanisms in the development of spondyloarthropathies are multifactorial. These include the possible role of infective micro-organisms which can by direct invasion lead to persistence of microbial antigens and thus trigger arthritis or by cross-reactions with the host tissue lead to inflammatory symptoms or by cross-reactions with HLA-B27 trigger cytotoxic T-cell response. After the primary event, exaggerated inflammatory response can lead to amplification of inflammation. The components in the amplification of inflammation include hyperreactive neutrophils and serum factors such as enhanced production of activation products of complement in subjects with HLA-B27. The enhanced neutrophil function seems to persist in patients with previous severe inflammatory symptoms during acute reactive arthritis or in those with late inflammatory complications. The enhancement is probably caused by priming effect by lipopolysaccharide, which seems to persist for a long period in patients with acute reactive arthritis. Enhanced production of monokines can contribute to the enhanced inflammation in patients with spondyloarthropathies. The primed phagocytes can respond vigorously when rechallenged with antigenic load during a new infection, thus leading in some patients to recurrent or chronic inflammatory symptoms. Antimicrobial therapy or sulphasalazine by modifying antigen elimination or absorption can diminish inflammatory response during acute arthritis and in chronic spondyloarthropathies. Long-term follow-up studies are needed to find out whether prolonged therapies with these agents affect the prognosis of spondyloarthropathies.

Enhanced inflammatory reactivity in the pathogenesis of spondyloarthropathies

Pathogenesis of seronegative spondyloarthropathies such as ankylosing spondylitis and reactive arthritis is not known. Growing evidence indicates that microbial structures such as Chlamydia antigen and Yersinia antigen are present in the inflamed joints of patients with reactive arthritis. Microbial antigens can activate the host's inflammatory mechanisms. After the activation, the course of inflammation can be postulated to be affected by the host factors responsible for amplification of the inflammatory reaction and elimination of the foreign structures. Thus, the amplification, whether strong, moderate, or weak, may contribute to the degree of inflammatory tissue injury in patients with seronegative spondyloarthropathies. This review will discuss the role of increased inflammatory reactivity in the pathogenesis of HLA-B27 associated spondyloarthropathies, with special reference to reactive arthritis triggered by yersinia enteritis.

Theoretical models to explain the association of HLA-B27 with ankylosing spondylitis

A critical examination of the five different models proposed to explain the "AS-B27" problem, has demonstrated, that two of these, the two-gene theory and the plasmid theory are no longer considered to provide satisfactory explanations of the phenomena. The remaining three theories are molecular mimicry, chemotaxis hypothesis and the receptor theory. It is difficult at this stage to decide which of these three models provides the best solution to the "AS-B27" problem, but a majority of research workers favour the receptor theory.

Bowel infection predisposing to reactive arthritis

Postenteric reactive arthritis is one of several syndromes in which arthritis appears to be secondary to gastrointestinal tract pathology. A wide range of microbes may trigger this type of arthritis. On the other hand, there are differences between strains in their arthritogenic potential. Two possible mechanisms, not mutually exclusive, can be forwarded to explain these findings: first, particular characteristics of the infective organisms are necessary to initiate events leading to reactive arthritis and, second, particular anatomical locations and a certain degree of mucosal involvement are needed to initiate the process. Studies on humoral and cellular immune responses have not revealed any unifying feature that could explain the pathogenesis of reactive arthritis. The HLA allele B27 plays some kind of key role. Yet the elucidation of the fine structure of B27 specificity has not led to any immediate breakthrough in the understanding of the pathogenetic pathways. Experience of reactive arthritis associated with acquired immunodeficiency syndrome suggests that helper T cells are not involved. Antigen persistence may be connected with continuation of the inflammation. Recent developments in the serology of enteric bacterial infections will provide additional tools for uncovering the triggering agents in reactive arthritis. 'Idiopathic reactive arthritis' associated with clinically silent terminal ileitis is an interesting disease entity requiring further characterization.

Polymorphonuclear leucocyte motility in men with ankylosing spondylitis

The polymorphonuclear leucocyte (PMN) response to a chemotactic or chemokinetic stimulus is enhanced in men with ankylosing spondylitis (AS). This effect does not parallel the severity of disease activity or the size of the acute phase response, and it is independent of non-steroidal anti-inflammatory drug treatment. Polymorph function is normal in HLA-B27 positive brothers of probands with AS and in other HLA-B27 positive individuals in the absence of disease. Polymorph motility is also normal in patients with psoriasis vulgaris or Crohn's disease, indicating that enhanced PMN motility is not a non-specific consequence of all inflammatory disorders.

Sulfasalazine in the treatment of ankylosing spondylitis. A twenty-six-week, placebo-controlled clinical trial

Eighty-five patients with active ankylosing spondylitis (AS) were randomized to receive either sulfasalazine (less than or equal to 3 gm/day, mean 2.5) or placebo for 26 weeks. There was a statistically significant improvement, compared with baseline, in most of the clinical variables in patients receiving the active drug. Laboratory parameters (erythrocyte sedimentation rate, C-reactive protein, IgG, IgM, and IgA) also improved during the active treatment, suggesting a beneficial effect of sulfasalazine on AS. At the end of the treatment, significant differences between the sulfasalazine and placebo groups were observed in morning stiffness, chest expansion, erythrocyte sedimentation rate, and in all immunoglobulin classes. Two patients in each treatment group discontinued the trial because of side effects. Enteric-coated sulfasalazine seemed to be effective and well tolerated in patients with active AS.

Production of tumour necrosis factor and interleukin 1 by monocytes of patients with previous Yersinia arthritis

We studied production of tumour necrosis factor (TNF) and interleukin 1 (IL-1) by using purified peripheral blood monocytes of patients with previous yersinia arthritis (YA) and of healthy HLA-B27 positive and negative controls. Lipopolysaccharide-exposed cells of HLA-B27 positive and negative patients, and those of HLA-B27 positive controls, generated significantly more TNF than did HLA-B27 negative control cells. There was a positive correlation between the levels of TNF and IL-1. Our results give credence to the view that augmented production of phlogistic mediators may contribute to inflammatory symptoms in patients with HLA-B27 associated disease.

Polymorphonuclear leucocyte function and previous yersinia arthritis: correlation of enhanced superoxide production with late manifestations

Polymorphonuclear leucocyte (PMN) functions (migration in vitro, chemiluminescence, O-2 production, and aggregation) were studied in 32 patients with previous yersinia arthritis (YA). PMNs of 11 HLA-B27 positive patients who had chronic or recurrent inflammatory symptoms showed O-2 production significantly higher than that of PMNs of 11 HLA-B27 positive patients without late manifestations. Also, PMNs of both HLA-B27 positive and negative patients tended to show chemotactic and chemokinetic migration rates higher than those of control cells of healthy HLA-B27 negative subjects. These functional aberrations may play a part in the development of the patients' inflammatory symptoms.

Circulating inhibitor bound elastase in patients with ankylosing spondylitis and rheumatoid arthritis and the influence of sulphasalazine treatment

The plasma concentration of granulocyte elastase in complex with alpha 1 proteinase inhibitor was determined in 42 patients with ankylosing spondylitis (AS) and 33 patients with rheumatoid arthritis (RA). Significantly raised levels of plasma elastase were found in patients with RA, whereas patients with AS had normal values. No correlation was seen between the elastase values and erythrocyte sedimentation rate (ESR), serum haptoglobin, immunoglobulins, or polymorphonuclear cell (PMN) count in either of the patient groups. A correlation was found between the Ritchie index and plasma elastase in patients with RA. After three months' treatment with sulphasalazine a clinical improvement was seen and this paralleled a reduction of the acute phase reaction in both patient groups. A reduction of the circulating elastase values was seen in the patients with RA, whereas no change was seen in patients with AS.

Phagocyte function in reactive arthritis

The pathogenesis of reactive arthritis is multifactorial. The possible pathogenetic mechanisms include the role of microbial antigens which cross-react with the host tissue or trigger cytotoxic immune response. In addition an exaggerated inflammatory response of the host may contribute to the clinical picture of the acute arthritis and its late sequels. In this review, we present data showing that HLA-B27 positive subjects show enhanced neutrophil (PMN) migration and their sera support PMN migration more than HLA-B27 negative sera. Enhanced PMN function is persistent in patients with previous severe reactive arthritis or with late inflammatory sequels. In addition to hyperreactive PMNs, monocytes from patients with previous yersinia arthritis, but also from healthy HLA-B27 positive subjects, respond to stimulation with lipopolysaccharide by enhanced production of inflammatory monokines compared with HLA-B27 negative healthy controls. Thus, hyperreactive phagocytes can contribute to the severe inflammatory complications seen in patients with reactive arthritis. The primed phagocytes can also respond vigorously when stimulated either with endogenous mediators of inflammation or with endotoxin released during a new infection or as a sequel of change in the mucosal permeability described in patients with spondyloarthropathy.

T lymphocytes in ankylosing spondylitis and the influence of sulphasalazine treatment

Twenty-nine patients with ankylosing spondylitis (AS) were studied in an attempt to evaluate the role of T lymphocytes in this disease and a possible influence of treatment. The proportions of various T cell subpopulations in blood were assessed with monoclonal antibodies. Before treatment the proportions of Leu-4+ cells and Leu 3a+ cells were decreased while Leu-2a+ lymphocytes appeared in normal proportions. Leu-7+ cells appeared in increased proportions. An increased proportion of Leu-M1 positive cells were identified in the lymphocyte preparation from the patients, possibly reflecting the presence of activated granulocytes. Activation of the different cell types was studied with double staining technique. No activated Leu-3a+ or Leu-2a+ lymphocytes were present in blood when the patients were analyzed as one group, but when divided into subgroups according to inflammatory activity, the highest levels of activated Leu-2a+ lymphocytes were found in the group with active disease. Functional assays measuring DNA synthesis of T and B cells were normal. After three months treatment with sulphasalazine the patients showed clinical and laboratory improvement. The proportion of activated Leu-2a+ cells decreased during treatment, but no other changes occurred in the lymphocyte markers or lymphocyte functional tests. A patient control group showed no clinical improvement nor any changes in T cell markers. Our results support the concept that AS is a disease which affects the lymphocyte system and that the improvement induced by sulphasalazine may involve actions on this system.

Raised circulating levels of the eosinophil cationic protein in ankylosing spondylitis: relation with the inflammatory activity and the influence of sulphasalazine treatment

The possibility of eosinophil involvement in ankylosing spondylitis (AS) was investigated by measuring serum levels of eosinophil cationic protein (ECP), a specific granule constituent of eosinophils. In a group of 48 patients with AS we found a threefold increase of the mean serum levels of ECP compared with a reference group (p less than 0.001). The blood eosinophil counts were similar in patients and controls. A correlation was found between ECP and inflammatory activity defined by erythrocyte sedimentation rate (ESR) and serum haptoglobin. Fifteen patients were studied before and after three months' treatment with sulphasalazine (2-3 g/day). The ECP levels decreased in 13/15 and this paralleled reduction of the acute phase reaction and improvement of clinical parameters. The results point to eosinophil activation as part of the inflammatory process in AS. The signs of reduced eosinophil activation during sulphasalazine treatment suggest either a drug mediated, direct effect on eosinophils or an effect on the inflammatory mechanism stimulating eosinophils.

Polymorphonuclear leucocyte function and previous yersinia arthritis: enhanced chemokinetic migration and oxygen radical production correlate with the severity of the acute disease

Polymorphonuclear leucocyte (PMN) functions (migration in vitro, chemiluminescence, O-2 production, binding of chemotactic peptide, and aggregation) were studied in HLA-B27 positive patients with previous yersinia arthritis (YA). PMNs of patients whose disease had been severe showed chemokinetic and chemiluminescence responses significantly higher than the PMNs of those with a mild disease. The results support the view that enhanced PMN function contributes to inflammatory symptoms in patients with YA.

IgA antibodies to gram-negative bacteria in the serum and saliva of patients with ankylosing spondylitis

The concentration of IgA and titre of IgA antibodies to several Gram-negative bacteria were measured in the serum and parotid saliva of patients with AS and normal tissue-typed individuals. Salivary IgA and antibody levels in the patients were identical with the control population. The serum antibody level against Yersinia enterocolica 0:3 was slightly raised in patients but there was no difference in the reactions to Klebsiella oxytoca strain MX100 or Escherichia coli 0111.B4. The serum IgA level was elevated in patients with AS, irrespective of HLA B27. We conclude that this approach is unlikely to provide convincing evidence of a link between Gram-negative bacteria and ankylosing spondylitis.

Yersinia arthritis, immune functions and histocompatibility antigens

Secondary immune response to tetanus toxoid (TT), monocyte function, and generation of suppressor cells were studied in patients with previous yersinia arthritis (YA) and healthy controls. A comparison of HLA-B27 positive and negative subjects revealed that leukocytes from the former showed significantly higher responses to TT but not to a variety of other antigens in a lymphocyte proliferation test, and higher rates of migration in a leukocyte migration inhibition assay in the absence of TT. The enhanced migration of leukocytes supports the concept that hyper-reactive neutrophils contribute to inflammatory symptoms in HLA-B27 positive subjects, irrespective of previous YA. No correlation was found between HLA-DR specificities and YA. However, HLA-DR2/HLA-B7 was associated with high suppressor cell activity and low serum levels of anti-TT-antibodies. This accords with the view that HLA-DR antigens play a role in the regulation of immune response.