Proinflammatory Microbial Products as Etiologic Agents of Inflammatory Arthritis

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.

Antibodies to the constitutive 73-kd heat shock protein: a new marker of mixed connective tissue disease?

PURPOSE, PATIENTS, AND METHODS

This report documents the finding of an elevated titer of IgG reacting with the constitutive bovine 73-kd heat shock protein (HSP) in the serum of patients with rheumatoid arthritis, scleroderma, and mixed connective tissue disease (MCTD).

RESULTS AND CONCLUSIONS

Further characterization of antibodies from patients with MCTD showed that the antibodies also recognize the human constitutive 73-kd HSP, but not the inducible 72-kd isoform. Very high levels of antibodies appeared to be specific for MCTD; the differences between levels in patients with MCTD and those in healthy subjects (blood donors) were highly significant (p < 10(-8)), with no values in this group of patients overlapping with those in the controls. This parameter might therefore represent a new diagnostic marker for this disease.

Anaesthesia and rheumatoid arthritis

A review of the implications of rheumatoid arthritis on peri-operative anaesthetic management is presented. Pre-operative assessment should include a careful search for articular and systemic manifestations of the disease that may complicate intraoperative care. Drug disposition may vary from the normal patient as a result of changes in serum protein binding, together with possible exaggeration of pharmacodynamic responses. Airway management presents one of the greatest challenges to the anaesthetist, and care in manipulation of the cervical spine is paramount.

Endothelial cells and the pathogenesis of rheumatoid arthritis in humans and streptococcal cell wall arthritis in Lewis rats

Endothelial cells play a fundamental role in the pathogenesis of chronic inflammatory arthritis in humans such as rheumatoid arthritis (RA), as well as experimental animal models such as streptococcal cell wall (SCW) arthritis in Lewis (LEW/N) rats. This review summarizes data in support of this concept. The earliest apparent abnormalities in synovial tissues of patients with RA and Lewis rats with SCW arthritis appear to reflect microvascular endothelial cell activation or injury. At the molecular level, the abnormalities include enhanced expression by endothelial cells of activation markers such as class II major histocompatibility complex antigens, phosphotyrosine, leukocyte adhesion molecules, oncoproteins such as c-Fos and c-Myc, and metalloproteinases such as collagenase and transin/stromelysin. The development of severe, chronic, destructive arthritis is dependent upon thymic-derived lymphocytes and is accompanied by tumorlike proliferation of cells in the synovial connective tissue stroma (blood vessels and fibroblastlike cells), which results in resorptive destruction of bone and cartilage. Multiple criteria support the analogy to a neoplastic process. Paracrine and autocrine factors such as interleukin-1 (IL-1), platelet-derived growth factor (PDGF), transforming growth factor-beta (TGF-beta), and heparin-binding fibroblast growth factors (HBGF, FGF) appear to play important roles in the generation of these lesions. Finally, in addition to the autocrine and paracrine regulatory factors, neuroendocrine factors, particularly the hypothalamic-pituitary-adrenal axis, appear to be involved in the counterregulation of the inflammatory process. The counterregulatory effects are mediated, in part, by inhibition of endothelial cell activation by corticosteroids.

The role of infectious agents in the spondylarthropathies

The clinical similarities of the spondylarthropathies and their frequent association with both HLA B27 and microbial infections suggest common pathogenetic mechanisms. The latter may include deposition of immune complexes containing bacterial antigens. or cross-reactivity of such antigens with host target tissue or responding cell antigens. Enteric bacteria, chlamydia and mycoplasma are all candidate etiologic agents, but proof is difficult because they are often found as normal flora, although only genetically susceptible individuals may acquire disease, and many patients have been treated with antibiotics before they can be studied. Nonetheless, a role for endogenous bacteria in reactive arthritis at least seems certain, and should stimulate further investigation into similar pathogenetic mechanisms in other chronic arthritides.