Chlamydia trachomatis nucleic acids can be found in the synovium of some asymptomatic subjects

Mediation of Interleukin-23 and Tumor Necrosis Factor-Driven Reactive Arthritis by Chlamydia-Infected Macrophages in SKG Mice

OBJECTIVE

ZAP-70^W163C BALB/c (SKG) mice develop reactive arthritis (ReA) following infection with Chlamydia muridarum. Since intracellular pathogens enhance their replicative fitness in stressed host cells, we examined how myeloid cells infected with C muridarum drive arthritis.

METHODS

SKG, Il17a-deficient SKG, and BALB/c female mice were infected with C muridarum or C muridarum luciferase in the genitals. C muridarum dissemination was assessed by in vivo imaging or genomic DNA amplification. Macrophages were depleted using clodronate liposomes. Anti-tumor necrosis factor (anti-TNF) and anti-interleukin-23p19 (anti-IL-23p19) were administered after infection or arthritis onset. Gene expression of Hspa5, Tgtp1, Il23a, Il17a, Il12b, and Tnf was compared in SKG mice and BALB/c mice.

RESULTS

One week following infection with C muridarum, macrophages and neutrophils were observed to have infiltrated the uteri of mice and were also shown to have carried C muridarum DNA to the spleen. C muridarum load was higher in SKG mice than in BALB/c mice. Macrophage depletion was shown to reduce C muridarum load and prevent development of arthritis. Compared with BALB/c mice, expression of Il23a and Il17a was increased in the uterine and splenic neutrophils of SKG mice. The presence of anti-IL-23p19 during infection or Il17a deficiency suppressed arthritis. Tnf was overexpressed in the joints of SKG mice within 1 week postinfection, and persisted beyond the first week. TNF inhibition during infection or at arthritis onset suppressed the development of arthritis. Levels of endoplasmic reticulum stress were constitutively increased in the joints of SKG mice but were induced, in conjunction with immunity-related GTPase, by C muridarum infection in the uterus.

CONCLUSION

C muridarum load is higher in SKG mice than in BALB/c mice. Whereas proinflammatory IL-23 produced by neutrophils contributes to the initiation of C muridarum-mediated ReA, macrophage depletion reduces C muridarum dissemination to other tissues, tissue burden, and the development of arthritis. TNF inhibition was also shown to suppress arthritis development. Our data suggest that enhanced bacterial dissemination in macrophages of SKG mice drives the TNF production needed for persistent arthritis.

Perspectives on the Intracellular Bacterium Chlamydia pneumoniae in Late-Onset Dementia

Purpose of Review

Chronic diseases remain a daunting challenge for clinicians and researchers alike. While difficult to completely understand, most chronic diseases, including late-onset dementias, are thought to arise as an interplay between host genetic factors and environmental insults. One of the most diverse and ubiquitous environmental insults centers on infectious agents. Associations of infectious agents with late-onset dementia have taken on heightened importance, including our investigations of infection by the intracellular respiratory bacterium, Chlamydia pneumoniae (Cpn), in late-onset dementia of the Alzheimer’s type.

Recent Findings

Over the last two decades, the relationship of this infection to pathogenesis in late-onset dementia has become much clearer. This clarity has resulted from applying contemporary molecular genetic, biochemical, immunochemical, and cell culture techniques to analysis of human brains, animal models, and relevant in vitro cell culture systems. Data from these studies, taken in aggregate form, now can be applied to evaluation of proof of concept for causation of this infection with late-onset disease. In this evaluation, modifications to the original Koch postulates can be useful for elucidating causation.

Summary

All such relevant studies are outlined and summarized in this review, and they demonstrate the utility of applying modified Koch postulates to the etiology of late-onset dementia of the Alzheimer’s type. Regardless, it is clear that even with strong observational evidence, in combination with application of modifications of Koch’s postulates, we will not be able to conclusively state that Cpn infection is causative for disease pathogenesis in late-onset dementia. Moreover, this conclusion obtains as well for the putative causation of this condition by other pathogens, including herpes simplex virus type 1, Borrelia burgdorferi, and Porphyromonas gingivalis.

Circulating serum miR-223-3p and miR-16-5p as possible biomarkers of early rheumatoid arthritis

Small non-coding RNAs have emerged as possible biomarkers for various diseases including autoimmune diseases. A number of studies have demonstrated that the expression of specific microRNAs (miRNAs) is dysregulated in rheumatoid arthritis (RA). So far, all studies on miRNAs in RA patients have been performed using either microarray or reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analyses. Compared to RT-qPCR and microarray analyses, next-generation sequencing (NGS) allows the genome-wide analysis of small RNAs and the differentiation between miRNAs that differ by a single nucleotide. The application of NGS to the analysis of small RNAs circulating in sera of RA patients has not been reported. This study provides a global overview of the circulating small RNAs in the sera of RA patients and healthy subjects and identifies differences between these groups using NGS. Several classes of small RNAs, including hY RNA-derived fragments, tRNA-derived fragments and miRNAs, were determined. Differentially expressed individual small RNAs were verified by RT-qPCR. The levels of two miRNAs, miR-223-3p and miR-16-5p, were significantly lower in the sera from early RA patients than in those from established RA patients and healthy controls. In contrast, the serum level of miR-16-5p was higher in patients with established RA than in healthy control samples. These miRNAs may not only serve as biomarkers, but may also shed more light on the pathophysiology of RA.

A study of pre-operative presence of micro-organisms in affected knee joints of rheumatoid arthritis patients who need total knee arthroplasty

BACKGROUND

To evaluate, by way of intraoperative tissue culture and pathological study, the pre-operative presence of micro-organisms in knee joints of patients with rheumatoid arthritis (RA) who need total knee arthroplasty (TKA).

METHODS

From November 2012 to January 2014, 47 patients with RA (53 knees) who needed TKA were included in this study. Patients received routine pre-operative examination and joint fluid routine and culture. Each RA patient was match-paired with one osteoarthritis (OA) patient. During arthrotomy, synovial tissue was reserved and portioned for culture, frozen section, and routine pathologic examination.

RESULTS

Pre-operative infection in all knees was ruled out. There were 12 RA patients (13 knees) with positive culture results: two Escherichia coli, two Staphylococcus epidermidis, two Staphylococcus aureus, one Proteus mirabilis, one Staphylococcus warneri, one Enterococcus faecalis, one Acinetobacter baumannii, one Candida albicans, one Ochrobactrum anthropi, and one Candida glabrata. Except for microabscess found in one RA patient, all pathological sections showed mild chronic inflammation but no infection. All patients with positive culture results were administered sensitive antibiotics for six weeks after surgery. Two patients had deep infection: one had a fused knee after a failed debridement, and the second was previously treated with an amphotericin injection.

CONCLUSION

Pre-operative presence of micro-organism in knee joints of RA patients is common (24.5%). This finding of a high incidence of pre-operative presence of micro-organism in joints of RA patients before arthroplasty may suggest a role of micro-organism in the pathogenesis of prosthetic joint infection (PJI). Intraoperative synovial tissue culture is valuable for diagnosis of this condition and in instruction of antibacterial treatment.

Recent advances and future directions in understanding and treating Chlamydia-induced reactive arthritis

INTRODUCTION

Reactive arthritis (ReA) is an inflammatory disease that can follow gastrointestinal or genitourinary infections. The primary etiologic agent for post-venereal ReA is the bacterium Chlamydia trachomatis; its relative, C pneumoniae, has also been implicated in disease induction although to a lesser degree. Studies have indicated that the arthritis is elicited by chlamydiae infecting synovial tissue in an unusual biologic state designated persistence. We review clinical aspects, host-pathogen interactions, and treatments for the disease. Areas covered: We briefly discuss both the historic and,more extensively, the current medical literature describing ReA, and we provide a discussion of the biology of the chlamydiae as it relates to elicitation of the disease. A summary of clinical aspects of Chlamydia-induced ReA is included to give context for approaches to treatment of the arthritis. Expert commentary: Basic research into the biology and host-pathogen interactions characteristic of C trachomatis has provided a wealth of information that underlies our current understanding of the pathogenic processes occurring in the ReA synovium. Importantly, a promising approach to cure of the disease is at hand. However, both basic and clinical research into Chlamydia-induced ReA has lagged over the last 5 years, including required studies relating to cure of the disease.

High Chlamydia Burden Promotes Tumor Necrosis Factor-Dependent Reactive Arthritis in SKG Mice

OBJECTIVE

Chlamydia trachomatis is a sexually transmitted obligate intracellular pathogen that causes inflammatory reactive arthritis, spondylitis, psoriasiform dermatitis, and conjunctivitis in some individuals after genital infection. The immunologic basis for this inflammatory response in susceptible hosts is poorly understood. As ZAP-70(W163C) -mutant BALB/c (SKG) mice are susceptible to spondylo-arthritis after systemic exposure to microbial β-glucan, we undertook the present study to compare responses to infection with Chlamydia muridarum in SKG mice and BALB/c mice.

METHODS

After genital or respiratory infection with C muridarum, conjunctivitis and arthritis were assessed clinically, and eye, skin, and joint specimens were analyzed histologically. Chlamydial major outer membrane protein antigen-specific responses were assessed in splenocytes. Treg cells were depleted from FoxP3-DTR BALB/c or SKG mice, and chlamydial DNA was quantified by polymerase chain reaction.

RESULTS

Five weeks after vaginal infection with live C muridarum, arthritis, spondylitis, and psoriasiform dermatitis developed in female SKG mice, but not in BALB/c mice. Inflammatory bowel disease did not occur in mice of either strain. The severity of inflammatory disease was correlated with C muridarum inoculum size and vaginal burden postinoculation. Treatment with combination antibiotics starting 1 day postinoculation prevented disease. Chlamydial antigen was present in macrophages and spread from the infection site to lymphoid organs and peripheral tissue. In response to chlamydial antigen, production of interferon-γ and interleukin-17 was impaired in T cells from SKG mice but tumor necrosis factor (TNF) responses were exaggerated, compared to findings in T cells from BALB/c mice. Unlike previous observations in arthritis triggered by β-glucan, no autoantibodies developed. Accelerated disease triggered by depletion of Treg cells was TNF dependent.

CONCLUSION

In the susceptible SKG strain, Chlamydia-induced reactive arthritis develops as a result of deficient intracellular pathogen control, with antigen-specific TNF production upon dissemination of antigen, and TNF-dependent inflammatory disease.

Role of genetics in infection-associated arthritis

Genetic discoveries in arthritis and their associated biological pathways spanning the innate and adaptive immune system demonstrate the strong association between susceptibility to arthritis and control of exogenous organisms. The canonical theory of the aetiology of immune-mediated arthritis and other immune-mediated diseases is that the introduction of exogenous antigenic stimuli to a genetically susceptible host sets up the environment for an abnormal immune response manifesting as disease. A disruption in host-microbe homeostasis driven by disease-associated genetic variants could ultimately provide the source of exogenous antigen triggering disease development. We discuss genetic variants impacting the innate and adaptive arms of the immune system and their relationship to microbial control and arthritic disease. We go on to consider the evidence for a relationship between HLA-B27, infection and arthritis, and then emerging evidence for an interaction between microbiota and rheumatoid arthritis.

Chlamydia and chronic arthritis

Certain bacterial infections have been demonstrated to be causative of reactive arthritis. The most common bacterial trigger of reactive arthritis is Chlamydia trachomatis. Chlamydia pneumoniae is another known cause, albeit far less frequently. Although Chlamydia-induced reactive arthritis will often spontaneously remit, approximately 30% of patients will develop a chronic course. Modern medicine has provided rather remarkable advances in our understanding of the chlamydiae, as these organisms relate to chronic arthritis and the delicate balance between host and pathogen. C. trachomatis and C. pneumoniae both have a remarkable ability to disseminate from the initial site of infection and establish persistently viable organisms in distant organ sites, namely the synovial tissue. How these persistent chlamydiae contribute to disease maintenance remains to be fully established, but recent data demonstrating that long-term combination antimicrobial treatment can not only ameliorate the symptoms but eradicate the persistent infection suggest that these chronically infecting chlamydiae are indeed a driving force behind the chronic inflammation. We are beginning to learn that this all appears possible even after an asymptomatic initial chlamydial infection. Both C. trachomatis and C. pneumoniae are a clear cause of chronic arthritis in the setting of reactive arthritis; the possibility remains that these same organisms are culpable in other forms of chronic arthritis as well.

Of bugs and joints: the relationship between infection and joints

The association between microbes and joints has existed since antiquity, and remains complex. Diagnosis is often times difficult to determine despite highly suspicious clinical characteristics for the presence of an underlying infection. Over the several past decades, considerable advances have occurred in diagnostic methodologies and therapy. However, the morbidity and mortality of septic arthritis remains high. Great advances have occurred in the diagnosis, pathogenesis, and therapeutic management of reactive arthritis, and there is evidence that when the responsible microorganism is Chlamydia trachomathis, complete remission and cure is possible. Emergent infections, especially viral, has been recognized, i.e. HIV, hepatitis C, and most recently Chikengunya virus, and in the case of HIV associated articular manifestations, the introduction of HAART has resulted in a decrease in the incidence and development of newer complications such as the immune reconstitution syndrome. The infectious etiology of rheumatoid arthritis is being strongly considered once again, and the exciting association with periodontal disease is at the forefront of intense research. The gut microbiota is also being investigated and new and most interesting data is being gathered of the potential role of commensal gut organisms and the pathogenesis of rheumatoid arthritis.

Identification of oral bacterial DNA in synovial fluid of patients with arthritis with native and failed prosthetic joints

OBJECTIVE

We examined the presence of bacterial DNA in synovial fluids of native or clinically aseptically failed prosthetic joints from patients having periodontal disease and arthritis to determine whether there is bacterial spread from the oral cavity to the joints.

METHODS

A total of 36 subjects were enrolled in the study. Among these, 11 were diagnosed with rheumatoid arthritis (RA) and 25 were diagnosed with osteoarthritis (OA). Eight patients with OA and 1 patient with RA had failed prostheses. Synovial fluid was aspirated from the affected hip or knee joint. Pooled subgingival plaque samples were collected, followed by clinical periodontal examination. Bacterial DNA was extracted from the collected synovial fluid and dental plaque samples were followed by polymerase chain reactions and DNA sequence analysis of the 16S-23S rRNA genes.

RESULTS

Of the 36 patients, bacterial DNA was detected in the synovial fluid samples from 5 patients (13.9%): 2 with RA (1 native and 1 failed prosthetic joints) and 3 with OA (1 native and 2 failed prosthetic joints). Of these 5 patients, 2 were diagnosed with periodontitis and had identical bacterial clones (Fusobacterium nucleatum and Serratia proteamaculans, respectively) detected in both the synovial fluid and the dental plaque samples. Fusobacterium nucleatum was the most prevalent, detected in 4 of the 5 positive samples. No cultures were done and no patients were treated with antibiotics or developed clinical infection.

CONCLUSIONS

The present findings of bacterial DNA in the synovial fluid suggest the possibility of organisms translocating from the periodontal tissue to the synovium. We suggest that patients with arthritis or failed prosthetic joints be examined for the presence of periodontal diseases and be treated accordingly.

Intrinsic danger: activation of Toll-like receptors in rheumatoid arthritis

RA is a debilitating disorder that manifests as chronic localized synovial and systemic inflammation leading to progressive joint destruction. Recent advances in the molecular basis of RA highlight the role of both the innate and adaptive immune system in disease pathogenesis. Specifically, data obtained from in vivo animal models and ex vivo human tissue explants models has confirmed the central role of Toll-like receptors (TLRs) in RA. TLRs are pattern recognition receptors (PRRs) that constitute one of the primary host defence mechanisms against infectious and non-infectious insult. This receptor family is activated by pathogen-associated molecular patterns (PAMPs) and by damage-associated molecular patterns (DAMPs). DAMPs are host-encoded proteins released during tissue injury and cell death that activate TLRs during sterile inflammation. DAMPs are also proposed to drive aberrant stimulation of TLRs in the RA joint resulting in increased expression of cytokines, chemokines and proteases, perpetuating a vicious inflammatory cycle that constitutes the hallmark chronic inflammation of RA. In this review, we discuss the signalling mechanisms of TLRs, the central function of TLRs in the pathogenesis of RA, the role of endogenous danger signals in driving TLR activation within the context of RA and the current preclinical and clinical strategies available to date in therapeutic targeting of TLRs in RA.

Developing the next generation of monoclonal antibodies for the treatment of rheumatoid arthritis

Rheumatoid arthritis is one of the commonest autoimmune diseases affecting 0.8% of the population. Over the last decade the treatment of this chronic disease has been revolutionized by the use of monoclonal antibodies and fusion proteins, targeting molecules like tumour necrosis factor alpha. Nevertheless, approximately one-third of subjects fail to respond to these therapies and therefore significant unmet medical need remains. Following a decade of use, clinical, government and regulatory agency expectations have changed for new antibodies therapies entering this highly competitive area. In this review, we discuss the current advances being made in antibody engineering and how they are being considered and used in the development of the next generation of antibodies to meet future expectations of healthcare providers, physicians and patients. Moreover, we discuss how pattern recognition receptors may provide new antibody tractable targets that may break the cycle of autoimmunity in rheumatoid arthritis.

Bacterial agents in spondyloarthritis: a destiny from diversity?

The spondyloarthritides (SpAs) are a group of diseases that share clinical, radiographic and laboratory features; these arthritides also display a tendency for family aggregation. Given the intimate relationship that these types of arthritis share, it suggests that the SpAs might share a common aetiology. Of all the SpAs, the role of bacteria is most clearly defined in reactive arthritis. Tremendous recent insights into the pathophysiology of reactive arthritis have been made, demonstrating that the causative bacteria play a much more complex role than previously thought. The bacteria that are proven to cause reactive arthritis, one of the five types of SpA, will be reviewed and their role in the pathophysiology of reactive arthritis will be examined. The speculative data suggesting links between various other bacteria and the other types of SpAs will be critically analysed. Although these data are not definitive, when viewed using the paradigm that the SpAs might actually represent a common end point from several diverse starting points, they are provocative, suggesting that bacteria might, indeed, be aetiological for the entire group of SpAs.

Blockade of Toll-like receptor 2 prevents spontaneous cytokine release from rheumatoid arthritis ex vivo synovial explant cultures

Introduction

The aim of this study was to examine the effect of blocking Toll-like receptor 2 (TLR2) in rheumatoid arthritis (RA) synovial cells.

Methods

RA synovial tissue biopsies, obtained under direct visualization at arthroscopy, were established as synovial explant cultures ex vivo or snap frozen for immunohistology. Mononuclear cell cultures were isolated from peripheral blood and synovial fluid of RA patients. Cultures were incubated with the TLR1/2 ligand, Pam3CSK4 (200 ng, 1 and 10 μg/ml), an anti-TLR2 antibody (OPN301, 1 μg/ml) or an immunoglobulin G (IgG) (1 μg/ml) matched control. The comparative effect of OPN301 and adalimumab (anti-tumour necrosis factor alpha) on spontaneous release of proinflammatory cytokines from RA synovial explants was determined using quantitative cytokine MSD multiplex assays or ELISA. OPN301 penetration into RA synovial tissue explants cultures was assessed by immunohistology.

Results

Pam3CSK4 significantly upregulated interleukin (IL)-6 and IL-8 in RA peripheral blood mononuclear cells (PBMCs), RA synovial fluid mononuclear cells (SFMCs) and RA synovial explant cultures (P < 0.05). OPN301 significantly decreased Pam3CSK4-induced cytokine production of tumour necrosis factor alpha (TNF-α), IL-1β, IL-6, interferon (IFN)-γ and IL-8 compared to IgG control in RA PBMCs and SFMCs cultures (all P < 0.05). OPN301 penetration of RA synovial tissue cultures was detected in the lining layer and perivascular regions. OPN301 significantly decreased spontaneous cytokine production of TNF-α, IL-1β, IFN-γ and IL-8 from RA synovial tissue explant cultures (all P < 0.05). Importantly, the inhibitory effect of OPN on spontaneous cytokine secretion was comparable to inhibition by anti-TNFα monoclonal antibody adalimumab.

Conclusions

These findings further support targeting TLR2 as a potential therapeutic agent for the treatment of RA.

Toll-like receptors: a new target in rheumatoid arthritis?

Rheumatoid arthritis (RA) is one of the most prevalent autoimmune diseases. It is characterized by chronic inflammation of the joint leading to its destruction. Although the initiating cause remains elusive, environmental factors and genetic background are known to contribute to the etiology of RA. The role of Toll-like receptors (TLRs) in innate immunity and their ability to recognize microbial products has been well characterized. TLRs are able to recognize endogenous molecules released upon cell damage and necrosis, and are present in RA synovial fluid. Although it appears unlikely that a pathogen underlies the pathogenesis or progression of RA, the release of endogenous TLR ligands during inflammation may activate TLRs and perpetuate the disease. An increasing body of circumstantial evidence implicates TLR signaling in RA, although, at present, their involvement is not defined comprehensively. Targeting individual TLRs or their signaling transducers may provide a more specific therapy without global suppression of the immune system.

Patients with Chlamydia-associated arthritis have ocular (trachoma), not genital, serovars of C. trachomatis in synovial tissue

Some individuals with a genital Chlamydia trachomatis infection develop inflammatory arthritis, but it is unknown whether particular chlamydial serovar(s) engender the disease more often than others. We defined serovar in synovial tissues from arthritis patients infected with this organism. DNA from synovial biopsies of 36 patients with PCR-confirmed synovial C. trachomatis was analyzed. Diagnoses included reactive arthritis, undifferentiated oligoarthritis, rheumatoid arthritis, and osteoarthritis. The chlamydial omp1 and trpA genes were amplified, cloned, and 10 or more clones from each sample were sequenced. The cytotoxin locus also was analyzed. omp1 sequences showed 2 patients having only C. trachomatis A serovar, 1 with only B, and 33 having only C, all ocular serovars. Analyses of trpA and the cytotoxin locus uniformly displayed standard ocular serovar characteristics for each patient. Identification of ocular chlamydial serovars in the synovia of arthritis patients is unexpected. These observations suggest that urogenital chlamydial infections, while consisting primarily of organisms of genital serovars, include some of ocular serovar(s). They further suggest that during such infections unknown selection pressures favor establishment of the latter in the synovium to the exclusion of genital serovar chlamydiae.

Reactive arthritis: clinical aspects and medical management

Reactive arthritis (ReA) is an inflammatory arthritis that arises after certain gastrointestinal or genitourinary infections, representing a classic interplay between host and environment. It belongs to the group of arthritidies known as the spondyloarthropathies. The classic syndrome is a triad of symptoms, including the urethra, conjunctiva, and synovium; however, the majority of patients do not present with this triad. Diagnostic criteria for ReA exist, but data suggest new criteria are needed. Epidemiologic and prospective studies have been difficult to perform because of over-reliance on the complete classic triad of symptoms and the different terms and eponyms used. Studies assessing various treatment strategies are ongoing.

Chlamydiae as etiologic agents in chronic undifferentiated spondylarthritis

OBJECTIVE

The majority of patients with Chlamydia-induced reactive arthritis do not present with the classic triad of arthritis, conjunctivitis/iritis, and urethritis. Moreover, acute chlamydial infections are often asymptomatic. The aim of the present study was to assess the prevalence of synovial Chlamydia trachomatis and Chlamydia pneumoniae infections in patients with chronic undifferentiated spondylarthritis (uSpA).

METHODS

Study patients met the European Spondylarthropathy Study Group criteria for SpA, without evidence of ankylosing spondylitis, psoriasis, inflammatory bowel disease, or preceding dysentery. Symptoms were present for >or=6 months. Each patient underwent a synovial biopsy; tissue and concomitantly obtained peripheral blood mononuclear cells (PBMCs) were analyzed by polymerase chain reaction (PCR) for C trachomatis and C pneumoniae DNA. Other data collected on the day of the biopsy included standard demographic information and medical history, including any known history of C trachomatis or C pneumoniae. Physical examination (including joint count, evaluation for dactylitis and/or enthesitis, and skin examination) and HLA-B27 typing were performed. Synovial tissue (ST) samples from 167 patients with osteoarthritis (OA) were used as controls.

RESULTS

Twenty-six patients met the entry criteria and underwent synovial biopsy (25 knee, 1 wrist). Sixteen of them (62%) were positive for C trachomatis and/or C pneumoniae DNA (10 for C trachomatis, 4 for C pneumoniae, and 2 for both). PCR analysis of ST revealed the presence of Chlamydia significantly more frequently in patients with uSpA than in OA controls (P<0.0001). No specific clinical characteristics differentiated Chlamydia-positive from Chlamydia-negative patients. PBMCs from 4 of the 26 uSpA patients (15%) were positive for Chlamydia, and Chlamydia was found in ST from 2 of these 4 patients. No significant correlation between PCR positivity and HLA-B27 positivity was found.

CONCLUSION

The frequency of Chlamydia-positive ST samples, as determined by PCR, was found to be significantly higher in patients with uSpA than in patients with OA. Our results suggest that in many patients with uSpA, chlamydial infection, which is often occult, may be the cause.

Detection and frequency of Chlamydia trachomatis DNA in synovial samples from Tunisian patients with reactive arthritis and undifferentiated oligoarthritis

We aimed to determine the frequency of Chlamydia trachomatis DNA in the synovial compartment of 34 arthritic patients. Chlamydia trachomatis DNA was detected using a nested PCR targeting the cryptic plasmid, the 16S rRNA gene and the outer membrane protein 1 gene. The presence of serum immunoglobulin (Ig)G and IgA antibodies against C. trachomatis was studied by a microimmunofluorescence assay and by an enzyme-linked immunosorbent assay, respectively. Synovial samples from 20 of 34 (59%) patients [nine with reactive arthritis (ReA), seven with undifferentiated oligoarthritis (UOA), two with rheumatoid arthritis and two with osteoarthritis] were positive for at least one C. trachomatis DNA sequence by nested PCR. The high sensitivity results most likely from the combination of a standardized automated MagNA Pure extraction method, PCR targeting three different C. trachomatis genes and the screening for C. trachomatis in synovial tissue and fluid samples. There was no correlation between the presence of C. trachomatis DNA in the joint and a Chlamydia-specific serologic response. Our data support that PCR is the method of choice to establish the diagnosis of Chlamydia-induced arthritis in patients with ReA. We suggest that this diagnosis might also be considered in C. trachomatis-positive patients previously classified as UOA.

Reiter's syndrome: the classic triad and more

Reiter's syndrome, also known as reactive arthritis, is the classic triad of conjunctivitis, urethritis, and arthritis occurring after an infection, particularly those in the urogenital or gastrointestinal tract. Dermatologic manifestations are common, including keratoderma blennorrhagicum, circinate balanitis, ulcerative vulvitis, nail changes, and oral lesions. Epidemiologically, the disease is more common in men, although cases have also been reported in children and women. The pathophysiology has yet to be elucidated, although infectious and immune factors are likely involved. Clinical presentation, severity, and prognosis vary widely. Treatment is difficult, especially in HIV-positive patients. Prognosis is variable; 15% to 20% of patients may develop severe chronic sequelae.

Mechanisms of disease: a 'DAMP' view of inflammatory arthritis

Innate immunity achieves our primary host defense by recognizing invading microorganisms through pathogen-associated molecular patterns (PAMPs) and by reacting to tissue damage signals called damage-associated molecular patterns (DAMPs). DAMP molecules, including high mobility group box 1 protein (HMGB-1), heat-shock proteins (HSPs), uric acid, altered matrix proteins, and S100 proteins, represent important danger signals that mediate inflammatory responses through the receptor for advanced glycation end-products (RAGE, also known as AGER) and Toll-like receptors, after release from activated or necrotic cells. The terms 'alarmins' and 'endokines' have also been proposed for DAMP molecules. A prototypic DAMP molecule, the nuclear protein HMGB-1, is either passively released by necrotic cells or actively secreted with delay by activated cells. S100A8, S100A9, and S100A12 are calcium-binding proteins expressed in the cytoplasm of phagocytes. They are rapidly secreted by activated monocytes or neutrophils, which are abundant in inflamed synovial tissue. HSPs are involved in the crosstalk between innate and adaptive immune systems, and primarily mediate immune regulatory functions. Multiple positive feedback loops between DAMPs and PAMPs and their overlapping receptors temporally and spatially drive these processes and may represent the molecular basis for the observation that infections, as well as nonspecific stress factors, can trigger flares in rheumatic diseases.

Campylobacter reactive arthritis: a systematic review

OBJECTIVE

To review the literature on the epidemiology of Campylobacter-associated reactive arthritis (ReA).

METHODS

A Medline (PubMed) search identified studies from 1966 to 2006 that investigated the epidemiology of Campylobacter-associated ReA. Search terms included: "reactive arthritis," "spondyloarthropathy," "Reiter's syndrome," "gastroenteritis," "diarrhea," "epidemiology," "incidence," "prevalence," and "Campylobacter."

RESULTS

The literature available to date suggests that the incidence of Campylobacter ReA may occur in 1 to 5% of those infected. The annual incidence of ReA after Campylobacter or Shigella may be 4.3 and 1.3, respectively, per 100,000. The duration of acute ReA varies considerably among reports, and the incidence and impact of chronic ReA from Campylobacter infection is virtually unknown.

CONCLUSIONS

Campylobacter-associated ReA incidence and prevalence varies widely among reviews due to case ascertainment differences, exposure differences, lack of diagnostic criteria for ReA, and perhaps genetics and ages of exposed individuals. At the population level it may not be associated with HLA-B27, and inflammatory back involvement is uncommon. Follow-up for long-term sequelae is largely unknown. Five percent of Campylobacter ReA may be chronic or relapsing (with respect to musculoskeletal symptoms).

Detection of DNA from a range of bacterial species in the knee joints of dogs with inflammatory knee arthritis and associated degenerative anterior cruciate ligament rupture

Mixtures of bacterial nucleic acids can often be detected in synovial joints affected with arthritis. We investigated the potential role of such mixtures of bacterial nucleic acids in the pathogenesis of arthritis in a naturally occurring canine model. Dogs with a common inflammatory knee arthritis in which associated pathological degenerative anterior cruciate ligament (ACL) rupture often develops were studied. Synovial biopsies were obtained from 43 dogs with the naturally occurring ACL rupture arthropathy, 12 dogs with normal knees and intact ACL, and 16 dogs with normal knees and experimentally induced ACL rupture. Using PCR, specimens were tested for Borrelia burgdorferi OspA and p66 gene sequences. Broad-ranging 16S rRNA primers were also used; 'panbacterial' PCR products were cloned and multiple clones were sequenced for bacterial identification. Synovium was also studied histologically. The presence of bacterial DNA within the synovium was significantly associated with the naturally occurring ACL rupture arthropathy (p<0.05); knee joints from 37% of these dogs were PCR-positive. Mixtures of bacterial DNA were common and often included environmental bacteria; predominant organisms included Borrelia burgdorferi and Stenotrophomonas maltophilia. DNA from environmental bacteria was only found in dogs with the naturally occurring ACL rupture arthopathy; joints from 33% of affected dogs contained such bacterial DNA. Synovial inflammation developed in dogs with both naturally occurring and experimentally induced ACL rupture, when compared with intact ACL controls (p<0.01). These results indicate that mixtures of DNA derived from environmental bacteria are commonly found in the knee joint of a naturally occurring canine arthropathy, often in association with a recognized joint pathogen. Our results also suggest that knee instability alone is not responsible for this finding and have led us to hypothesize that mixtures of bacterial DNA are an important causative factor in the pathogenesis of inflammatory arthritis in this canine model.

Reactive arthritis: defined etiologies, emerging pathophysiology, and unresolved treatment

ReA is unique in that it is one of the few disease states of which there is a known trigger. This insight into disease initiation has led to great advances in the pathophysiology. Despite this detailed knowledge, the proper treatment remains elusive. In the years to come it is possible that the specific treatment will be dictated by the triggering microbe.

Clinical Applications of the Polymerase Chain Reaction: An Update

The development, in the past decade, of nucleic acid amplification and detection methods is useful in the study of the etiopathogenesis, diagnosis, and management of a variety of clinical (including rheumatologic) disorders. An association between infectious agents and rheumatic disorders has been established through such methods as polymerase chain reaction. This article describes the principles behind polymerase chain reaction-based diagnosis and updates its clinical applications. It is beyond the scope of this article, however, to describe other nucleic acid amplification methods or to include a complete list of all polymerase chain reaction assays that have been developed. Other recent reviews offer additional details.

Detection of Chlamydia in the peripheral blood cells of normal donors using in vitro culture, immunofluorescence microscopy and flow cytometry techniques

BACKGROUND

Chlamydia trachomatis (Ct) and Chlamydia pneumoniae (Cp) are medically significant infectious agents associated with various chronic human pathologies. Nevertheless, specific roles in disease progression or initiation are incompletely defined. Both pathogens infect established cell lines in vitro and polymerase chain reaction (PCR) has detected Chlamydia DNA in various clinical specimens as well as in normal donor peripheral blood monocytes (PBMC). However, Chlamydia infection of other blood cell types, quantification of Chlamydia infected cells in peripheral blood and transmission of this infection in vitro have not been examined.

METHODS

Cp specific titers were assessed for sera from 459 normal human donor blood (NBD) samples. Isolated white blood cells (WBC) were assayed by in vitro culture to evaluate infection transmission of blood cell borne chlamydiae. Smears of fresh blood samples (FB) were dual immunostained for microscopic identification of Chlamydia-infected cell types and aliquots also assessed using Flow Cytometry (FC).

RESULTS

ELISA demonstrated that 219 (47.7%) of the NBD samples exhibit elevated anti-Cp antibody titers. Imunofluorescence microscopy of smears demonstrated 113 (24.6%) of samples contained intracellular Chlamydia and monoclonals to specific CD markers showed that in vivo infection of neutrophil and eosinophil/basophil cells as well as monocytes occurs. In vitro culture established WBCs of 114 (24.8%) of the NBD samples harbored infectious chlamydiae, clinically a potentially source of transmission, FC demonstrated both Chlamydia infected and uninfected cells can be readily identified and quantified.

CONCLUSION

NBD can harbor infected neutrophils, eosinophil/basophils and monocytes. The chlamydiae are infectious in vitro, and both total, and cell type specific Chlamydia carriage is quantifiable by FC.

Early cytokine profiles in the joint define pathogen clearance and severity of arthritis inChlamydia-induced arthritis in rats

OBJECTIVE

Although Chlamydia trachomatis-induced arthritis is among the most common rheumatic diseases having an identified infectious trigger, the pathogenesis of this arthritis is not well defined. We sought to investigate the host-microbe interactions that contribute to the severity of arthritis initiated by chlamydial infection.

METHODS

We established an experimental rat model of C. trachomatis-induced arthritis that recapitulates many pathologic features of the clinical disease. The severity of the arthritis was defined using an established histopathologic scoring system. Host clearance of the pathogen and local cytokine production were examined by enzyme-linked immunosorbent assays.

RESULTS

Lewis rats were susceptible to C. trachomatis-induced arthritis, whereas BN rats were relatively resistant to this disease. Significant differences in the histopathologic severity of arthritis were originally observed on day 21, and this prompted an examination of the acute phase of the arthritis. As early as day 5 after the onset of the arthritis, pathologic changes in Lewis rats were more severe than those in BN rats. An evaluation of the role of complement using cobra venom factor treatment excluded complement as being the key to differential sensitivity, because decomplementation did not eliminate the differences in arthritis severity between Lewis and BN rats. Host clearance, in contrast, was significantly different between the rat strains, with BN rats showing more prompt and effective clearance of the pathogen from both synovial tissues and spleen compared with Lewis rats. Local cytokine profiles demonstrated that host resistance was characterized by enhanced synovial expression of tumor necrosis factor alpha, interferon-gamma (IFNgamma), and interleukin-4.

CONCLUSION

These studies demonstrated that cytokines thought to be proinflammatory in nature can play an important role in host defense in infection-triggered arthritis and serve to highlight the dynamic cytokine relationships that constitute effective host-pathogen interactions.

Reactive arthritis

Reactive arthritis (ReA) was known as Reiter's disease or Fiessinger-Leroy disease for nearly 100 years. However, during the past 30 years the disease has been known as reactive arthritis, a member of the spondyloarthritis family. Despite knowing the initiating event (infection) and genetic constitution (many patients have HLA-B27) of ReA, a model of interplay between environment and genetics, its pathogenesis is still incompletely known. This review covers the epidemiology, clinical features, treatment, and prognosis of ReA.

Spondyloarthritis: update on pathogenesis and management

A great deal of progress has occurred in the past few years in elucidating the causes and designing new treatments for ankylosing spondylitis and other types of spondyloarthritis. In addition to the human leukocyte antigen (HLA)-B27 and other major histocompatibility complex (MHC) genes, chromosomal regions and genes elsewhere in the genome are being implicated both in disease susceptibility and severity. The various ways HLA-B27 may function in causing spondyloarthritis now are better understood to encompass not only antigen presentation but also other mechanisms, possibly all being operative in pathogenesis (misfolding of the HLA-B27 molecule, impaired intracellular killing of bacteria, and HLA-B27 itself serving as an autoantigen). Specific enteric and sexually acquired infections can trigger reactive arthritis, though no specific microbe has been identified in other forms of spondyloarthritis. Intestinal inflammation with impairment of the gut:blood barrier may be operative in driving ankylosing spondylitis and enteropathic arthritis. A number of treatments have been tried in spondyloarthritis, including older agents such as methotrexate and sulfasalazine but also newer drugs such as pamindronate. The recent introduction of tumor necrosis factor (TNF) blockers in the treatment of spondyloarthritis has offered the most hope in not only relieving symptoms and signs of both peripheral arthritis and enthesitis but also spinal disease, which often has been refractory to other agents. Their high cost and considerable side effect profile, however, have necessitated the establishment of guidelines for their use in these diseases in order to target the patient in whom they are likely to have the most benefit.

Management of reactive arthritis

Reactive arthritis (ReA) is an aseptic form of articular inflammation induced by infections mainly localised in the gastrointestinal (enteroarthritis) or urogenital (uroarthritis) tracts. The bacteria principally involved as causative agents are Chlamydia, Salmonella, Shigella, Campylobacter and Yersinia. The clinical picture is usually characterised by a mono-oligoarthritis of the lower limbs. Axial involvement is possible and extra-articular manifestations such as enthesitis, tenosynovitis, bursitis and dactylitis are frequent. NSAIDs and sulfasalazine are still the drugs most commonly used in the treatment of ReA. Steroids are administered when inflammatory symptoms are resistant to NSAIDs. Experiences with other DMARDs (disease modifying antirheumatic drugs) such as azathioprine, methotrexate and cyclosporin, have been sporadically reported and they can be employed in patients that are unresponsive to the more usual medicaments. The intake of antibacterials (tetracyclines) may be useful in uroarthritis but have not been so successful in enteroarthrits. In more aggressive cases, or when ReA evolves towards ankylosing spondylitis, TNF-alpha blockers could represent an effective choice.

Hematogenous infection of the human temporomandibular joint

Objective This study was designed to discover the relationship between bacteremia and the presence of specific bacterial species in the synovial fluid of the human temporomandibular joint (TMJ). Study design Sixteen volunteers (female to male, 1:2.2; average age, 30.00 +/- 9.93 years) who received operations via intraoral incision participated in this study. Samples from the blood and TMJ synovial fluid of the patients were taken preoperatively and postoperatively and analyzed by PCR assays with specific primers for the clinically important bacteria Staphylococcus aureus , Streptococcus mitis , and beta-hemolytic Streptococcus . Results PCR-based assays revealed the occurrence of S aureus in 68.8% and 50% of the total blood and synovial fluid samples collected immediately after the operations, which statistically differed from the preoperative samples ( P < .05). However, the frequency of the other bacteria, S mitis and beta-hemolytic Streptococcus , in pre- and postoperative blood samples had no such a difference ( P > .05). The chi-square test showed a significant association between the presence of S aureus in the blood and in TMJ synovial fluid (chi 2 = 6.409, P < .05), and the probability of hematogenous infection of the TMJ was estimated as 55.5%. Conclusion Hence, the data obtained provided evidence that the invasion of S aureus into TMJ synovial fluid was due to the presence of these bacteria in the blood. To our knowledge, this is the first report of the bacteremia-related mechanism of S aureus invasion in the human TMJ.

Role for Innate Immunity in Rheumatoid Arthritis

Innate immunity is the first line of defense against pathogenic microorganisms (bacteria, viruses, fungi, and parasites). After a long period of neglect, innate immunity is again recognized as a key mechanism not only in preventing invasion of the body by microorganisms, but also in contributing to the pathogenesis of autoimmune and inflammatory diseases by deviating the immune response or promoting the emergence of a regulatory response. The many factors involved in innate immunity often act in parallel or in alternation to generate adaptive immune responses. Innate immune responses are specific for groups of molecules or macromolecules found in components of microorganisms, usually the cell wall. The cellular and protein effectors of innate immunity are found in the rheumatoid synovium, and an increasing body of evidence indicates that they are directly involved in joint inflammation and in destruction of the joint cartilage and bone. In addition, they may have regulatory effects on inflammation and immunity. Whether innate immune mechanisms are causes or consequences of inflammation, and whether they regulate or amplify adaptive immune responses, they constitute a target of choice for new antiinflammatory and immunoregulating treatment strategies.

Immunohistochemistry of normal human knee synovium: a quantitative study

OBJECTIVE

To describe the immunohistochemical characteristics of knee synovium from normal healthy subjects.

METHODS

12 healthy subjects underwent needle biopsy of knee synovium. Using antibodies directed against CD3, CD4, CD8, L26, Kp-1,and HLA-DR, detailed quantitative immunohistochemical analysis of various cell subpopulations was undertaken.

RESULTS

The mean (SD) age of the subjects was 37 (9) years (five male, seven female). All had a negative history for arthritis, no knee pain, and a totally normal joint examination except for the presence of retropatellar crepitus in five. For technical reasons staining for all immunohistochemical markers could not be achieved in all subjects. CD3+ T lymphocytes were seen in nine of 10 subjects, either diffusely or, more commonly, in perivascular areas. CD4+ cells were seen in synovium in three of seven subjects and CD8+ cells in six of eight subjects, in almost equal numbers (CD4:CD8, 1.1:1). L26+ B lymphocytes were not seen in any biopsy. Kp1+ macrophages were found in 10 of 10 subjects, predominantly in surface lining cells, and in small numbers in diffuse and perivascular locations. HLA-DR+ cells were seen in 10 of 10 subjects, predominantly in surface lining cells and diffusely, but a few were seen perivascularly.

CONCLUSIONS

Synovium from apparently normal subjects contained a wide range of different cell subpopulations but no B cells. The significance of these immune cells in normal synovium is unclear. A better understanding of their role in normal synovium may be important in analysing the transition to synovitis.

HLA-B27-associated reactive arthritis: pathogenetic and clinical considerations

Current evidence supports the concept that reactive arthritis (ReA) is an immune-mediated synovitis resulting from slow bacterial infections and showing intra-articular persistence of viable, non-culturable bacteria and/or immunogenetic bacterial antigens synthesized by metabolically active bacteria residing in the joint and/or elsewhere in the body. The mechanisms that lead to the development of ReA are complex and basically involve an interaction between an arthritogenic agent and a predisposed host. The way in which a host accommodates to invasive facultative intracellular bacteria is the key to the development of ReA. The details of the molecular pathways that explain the articular and extra-articular manifestations of the disease are still under investigation. Several studies have been done to gain a better understanding of the pathogenesis of ReA; these constitute the basis for a more rational therapeutic approach to this disease.

Role of peptidoglycan subtypes in the pathogenesis of bacterial cell wall arthritis

BACKGROUND

Bacterial cell wall (CW) arthritis develops in susceptible strains of rats after a single intraperitoneal injection of the CW from certain bacterial species, both pathogenic and non-pathogenic. For the development of chronic bacterial CW arthritis, the structure of the bacterial peptidoglycan (PG) has been found to be decisive.

OBJECTIVE

To define the role of PG subtypes in the pathogenesis of chronic bacterial CW arthritis.

METHOD

Arthritis was induced with CWs of Lactobacillus plantarum, L casei B, L casei C, and L fermentum. Gas chromatography-mass spectrometry was used to measure the presence of CW derived muramic acid in the liver and to determine PG subtypes. CWs were also tested for their resistance to lysozyme in vitro.

RESULTS

These results and those published previously indicate that PGs of CWs which induce chronic arthritis, no matter whether they were derived from strains of Streptococcus, Bifidobacterium, Collinsella, or Lactobacillus, all have lysine as the third amino acid of the PG stem peptide, representing PG subtypes A3alpha and A4alpha. Those strains which induce only transient acute arthritis or no arthritis at all do not have lysine in this position, resulting in different PG subtypes.

CONCLUSIONS

In vivo degradation of only those PGs with the subtypes A3alpha and A4alpha leads to the occurrence of large CW fragments, which persist in tissue and have good proinflammatory ability. CWs with other PG subtypes, even if they are lysozyme resistant, do not cause chronic arthritis, because the released fragments are not phlogistic. It is emphasised that a variety of microbial components not causing inflammation have been found in animal and human synovial tissue.

The presence of bacteria in the synovial fluid of the temporomandibular joint and clinical significance: preliminary study

PURPOSE

The objective of this study was to find any relation between the presence of specific bacterial species in the synovial fluid of the temporomandibular joint (TMJ) and clinical parameters.

PATIENTS AND METHODS

We studied 43 patients (male-to-female ratio, 1:1.69; average age, 34.37 +/- 14.55 years). Thirty-three patients had a displaced disc in the TMJ (DD group), and 10 patients did not have a displaced disc of the TMJ or any symptom related to TMJ disorders (NDD group). Clinical examinations were made to determine maximum mouth opening, joint sounds, previous trauma history, systemic disease, and TMJ pain. Six bacterial species that were reported in other studies were chosen to evaluate the presence of bacteria in the TMJ for this study.

RESULTS

Mycoplasma genitalium was most frequently detected in synovial fluid (86.0%). Staphylococcus aureus, Mycoplasma fermentans/orale, Actinobacillus actinomycetemcomitans, and Streptococcus mitis were detected in 51.2%, 37.2%, 25.6%, and 7.0% of samples, respectively. beta-Hemolytic Streptococcus was not detected. The prevalence of S aureus was significantly higher in the DD group than in the NDD group (P <.05). The patients who had M. fermentans/orale were 5.40 times more likely to be younger than 30 years than were those without M. fermentans/orale (P <.05). Those with M. genitalium were 5.81 times more likely to be female than were those without M. genitalium (P <.05).

CONCLUSION

The presence of S. aureus in TMJ synovial fluid was related to TMJ disorder symptoms and clinical parameters seemed to be influenced by bacterial presence in TMJ synovial fluid.

Normal intestinal microbiota in the aetiopathogenesis of rheumatoid arthritis

A series of observations have led to the hypothesis that normal intestinal microbiota in patients with rheumatoid arthritis may harbour, for genetic reasons, bacteria with cell walls capable of inducing arthritis. Differences occur between bacterial species, and even between strains of a single species, because some cell walls induce experimental chronic arthritis, whereas some others induce only a transient acute arthritis or no arthritis at all. In susceptible subjects, with continuous seeding of bacterial products from the gut, the synovial inflammation is followed by erosion, exposition of cartilage antigens, and self perpetuating chronic arthritis.

Microbial factors in spondyloarthropathies: insights from population studies

Infections and genetics play a role in the development of reactive arthritis. The clinical manifestations and severity of the features depend on the triggering infections and the epidemiologic setting. Reports from hospital-based series show the lowest frequency of reactive arthritis, but often, patients have severe arthritis associated with a high frequency of HLA-B27. At the population level, reactive arthritis occur in 7 to 15% of the infected subjects. The disease is usually mild, affects small joints, can be polyarticular, often rapidly disappears, and has a low association with HLA-B27. There also seems to be a change in the spectrum of triggering infections. Reports of Yersinia arthritis are less common, whereas arthritis in association with Campylobacter or Salmonella infections seems to be increasing. The role of early antimicrobial chemotherapy for the prevention of reactive arthritis needs to be studied.

Role of metacarpophalangeal joint anatomic factors in the distribution of synovitis and bone erosion in early rheumatoid arthritis

OBJECTIVE

To investigate the role of metacarpophalangeal (MCP) joint anatomic and biomechanical factors in the distribution of synovitis and bone erosion in early rheumatoid arthritis (RA).

METHODS

Thirty-three patients with early RA with clinically diagnosed MCP joint disease and 28 healthy controls were examined by magnetic resonance imaging of the second to fifth MCP joints of the dominant hand. T1 and T2 fat-suppressed coronal sequences were obtained to assess erosion, and dynamic contrast-enhanced images were acquired to assess synovitis in all of the RA patients and in 8 of the controls. Erosions were defined as bone defects with sharp margins observed using T1-weighted imaging in 2 planes, with a cortical break seen in at least 1 plane. The location of erosions was recorded. The volume of synovitis surrounding each MCP joint (divided into 8 regions) was calculated by summation of voxels derived from the maximal enhancement parameters. The synovial volumes adjacent to MCP joint collateral ligaments were determined by correcting synovial volumes for the positions of asymmetrically placed flexor tendons.

RESULTS

In patients with early RA in whom bone erosions were present, there was a propensity for involvement of the radial side of the second (P < 0.0001), third (P = 0.002), and fourth (P = 0.056) MCP joints, but not the fifth. Fifty-two of the 110 erosions (47.3%) occurred adjacent to the radial collateral ligaments of the second, third, and fourth MCP joints. The volume of synovitis was also greater on the radial side of the second (P < 0.0001) and third (P < 0.001) MCP joints. A predilection for synovitis in all of the MCP joints adjacent to the radial collateral ligaments was evident when the positional effects of the flexor tendon were considered. The position of radial collateral ligaments had an effect on erosion formation that was independent of synovitis. A predilection for radial bone damage was also evident in the controls, although lesions were 5-fold less frequent, were generally smaller, and had well-defined margins.

CONCLUSION

This study shows that there is a predilection for both synovitis and bone erosion formation on the radial side of the MCP joints in early RA, and that joint inflammation appears to drive the inherent tendency for bone damage on the radial side of joints. These findings have implications regarding the pathogenesis of joint damage in RA.

Infection of human fibroblast-like synovial cells with Chlamydia trachomatis results in persistent infection and interleukin-6 production

Recent studies have shown that the urogenital pathogen Chlamydia trachomatis to be a major bacterium triggering reactive arthritis (ReA), and is able to induce interleukin-6 (IL-6) production in human fibroblast-like synovial cells (FSC) in vitro. In the present study, we examined the correlation between IL-6 production and multiplication of chlamydia in FSC. All FSC from five patients secreted highly increased quantities of IL-6 in a dose-dependent and time-dependent fashion. Heat and UV inactivated chlamydia failed to enhance production of IL-6. When azithromycin was added to infected cultures of FSC at 0 or 48 h after infection, the level of IL-6 production was very low. Transmission electron microscopy of such infected cultures revealed many abnormal forms of chlamydia within the inclusions in FSC. From one step-growth curve experiments, it was suggested that C. trachomatis hardly multiplied in FSC. In contrast, in C. trachomatis infected HeLa 229 cells, chlamydia multiplied as usual, but little IL-6 production were found. These observations indicated that live chlamydia and the persistence of chlamydia may be essential for stimulating the synthesis of IL-6 in FSC.

Applications of polymerase chain reaction in rheumatology

Polymerase chain reaction (PCR) is a highly sensitive and specific method for detection and quantification of specific nucleic acids from a clinical sample. With its use, genetic, infectious, neoplastic, and autoimmune diseases can be diagnosed and managed with a high level of sensitivity, accuracy, and rapidity. This technique exactly reproduces unlimited copies of DNA, even if only a small amount are present initially. PCR assays can detect presence of fastidious and slow-growing microorganisms, such as chlamydia, mycoplasmas, mycobacterias, and viruses directly from clinical specimens and also can detect antimicrobial resistance. The value of viral load measurement by nucleic acid amplification in the management of patients with HIV infection or hepatitis C has also been well established. From the point of view of a clinician, the applications of PCR are focused mainly in the amplification and detection of diagnostic DNA segments from the genomes of both pathogens and patients.

Chlamydial conjunctivitis (in adults), uveitis, and reactive arthritis, including SARA. Sexually acquired reactive arthritis

This chapter deals with Chlamydia -induced ocular and rheumatic diseases of the adult. All of these may follow a primary urogenital infection with Chlamydia trachomatis in genetically predisposed patients. Besides the infection with Chlamydia trachomatis, infections with Chlamydia pneumoniae and Chlamydia psittaci are also discussed as possible causative agents. Chlamydial conjunctivitis is frequently a secondary infection, and the organism is transferred from the urogenital tract to the eye by autoinoculation. Uveitis and reactive arthritis are believed to be triggered - among other infections - by a preceding urogenital infection. Both of them are closely associated with HLA-B27 positivity. The simultaneous occurrence of uveitis and reactive arthritis is termed Reiter's syndrome. We report on clinical characteristics, diagnosis and the role of Chlamydia in the pathogenesis of chlamydial conjunctivitis, uveitis and reactive arthritis as well as on the currently recommended treatment regimens.

Infectious background of patients with a history of acute anterior uveitis

OBJECTIVE

To study the infectious background of patients with a history of acute anterior uveitis (AAU) and healthy control subjects.

METHODS

Sixty four patients with previous AAU and 64 sex and age matched controls were studied. Serum antibodies to Salmonellae, Yersiniae, Klebsiella pneumoniae, Escherichia coli, Proteus mirabilis, Campylobacter jejuni, and Borrelia burgdorferi were measured using enzyme linked immunosorbent assay (ELISA), and antibodies to Chlamydia trachomatis and Chlamydia pneumoniae by microimmunofluorescence test. Peripheral blood mononuclear cells (PBMCs), separated by density gradient centrifugation, were studied for Salmonella and Yersinia antigens by means of an immunofluorescence test, and for C pneumoniae DNA with a polymerase chain reaction (PCR).

RESULTS

Neither prevalence nor levels of single microbial antibodies studied differed between the patients and control subjects, or between subgroups of patients created on the basis of clinical characteristics. In logistic regression analysis, the high number of recurrences (>10) of AAU was independently related to the presence of single or multiple bacterial antibodies (p=0.04). None of the PBMC samples of the patients were positive for Yersinia or Salmonella antigens. C pneumoniae PCR was positive in a patient who was negative for C pneumoniae antibodies.

CONCLUSION

Although neither the prevalence nor the levels of single microbial antibodies studied differed between the patients and the controls, current data suggest that the presence of single or multiple antibodies in patients with many recurrences of AAU compared with patients with none or few recurrences may be a sign of repeated infections, antigen persistence, or raised innate immune responsiveness.