Salmonella-triggered reactive arthritis

Salmonella Exhibit Altered Cellular Localization in the Presence of HLA-B27 and Codistribute with Endo-Reticular Membrane

Salmonella enteritica (S. enteritica) induce and require unfolded protein response (UPR) pathways for intracellular replication. Salmonella infections can lead to reactive arthritis (ReA), which can exhibit associations with Human Leucocyte Antigen (HLA)-B^∗27 : 05. S. enteritica normally reside in a juxtanuclear position to the Golgi apparatus, representing the formation and residence within the Salmonella-containing vacuole (SCV). Changes in cellular localization of infecting Salmonella can alter their ability to replicate. We therefore used isogenic epithelial cell lines expressing physiological levels of HLA-B^∗27 : 05 heavy chain (HC) and a control HLA-B allele, HLA-B^∗35 : 01.HC to determine any changes in Salmonella localization within epithelial cells. Expression of HLA-B^∗27 : 05 but not HLA-B^∗35 : 01 was associated with a quantifiable change in S. enteritica cellular distribution away from the Golgi apparatus. Furthermore, the Salmonella requirements for UPR induction and the consequences of the concomitant endoplasmic reticulum (ER) membrane expansion were determined. Using confocal imaging, S. enteritica bacteria exhibited a significant and quantifiable codistribution with endo-reticular membrane as determined by ER tracker staining. Isogenic S. enterica Typhimurium mutant strains, which can infect but exhibit impaired intracellular growth, demonstrated that the activation of the UPR was dependent on an integral intracellular niche. Therefore, these data identify cellular changes accompanying Salmonella induction of the UPR and in the presence of HLA-B27.

Involvement of the tuberomammillary nucleus of the hypothalamus in the modulation of nociception and joint edema in a model of monoarthritis

AIMS

Investigate the involvement of the histaminergic projections from tuberomammillary nucleus (TMN) to the spinal cord in the modulation of nociception and peripheral edema in a model of monoarthritis.

MAIN METHODS

Subacute monoarthritis was induced by an intraarticular injection of carrageenan followed by LPS 72 h later. Disability and joint edema were assessed at the 3rd hour after LPS and at every hour up to 6 h.

KEY FINDINGS

Intrathecal administration of histamine potentiated joint incapacitation and edema, while the H1R antagonist cetirizine decreased both. The H3R agonist immepip decreased both incapacitation and edema, while the H3R antagonist thioperamide had the opposite effect. The microinjection of glutamate into the ventral TMN (vTMN) caused an increase of incapacitation and articular edema, whereas the blockade of this nucleus by cobalt chloride inhibited both parameters. Intrathecal administration of cetirizine prevented the increase of incapacitation and joint edema caused by glutamate microinjection into the vTMN. Similarly, an intrathecal injection of the NKCC1 cotransporter inhibitor bumetanide prevented the effects of glutamate microinjection into the vTMN, whereas coadministration of histamine with bumetanide only inhibited the potentiation of joint edema. A microinjection of orexin B into the vTMN potentiated incapacitation and joint edema, while coadministration of the OX1/2 receptor antagonist almorexant with orexin B did not.

SIGNIFICANCE

These data support the notion that TMN participates in the modulation of a peripheral inflammatory process by means of histaminergic projections to the spinal cord, and the hypothalamus may trigger TMN activation by means of glutamate and orexin.

High-content screening image dataset and quantitative image analysis of Salmonella infected human cells

OBJECTIVES

Salmonella bacteria can induce the unfolded protein response, a cellular stress response to misfolding proteins within the endoplasmic reticulum. Salmonella can exploit the host unfolded protein response leading to enhanced bacterial replication which was in part mediated by the induction and/or enhanced endo-reticular membrane synthesis. We therefore wanted to establish a quantitative confocal imaging assay to measure endo-reticular membrane expansion following Salmonella infections of host cells.

DATA DESCRIPTION

High-content screening confocal fluorescence microscopic image set of Salmonella infected HeLa cells is presented. The images were collected with a PerkinElmer Opera LX high-content screening system in seven 96-well plates, 50 field-of-views and DAPI, endoplasmic reticulum tracker channels and Salmonella mCherry protein in each well. Totally 93,300 confocal fluorescence microscopic images were published in this dataset. An ImageJ high-content image analysis workflow was used to extract features. Cells were classified as infected and non-infected, the mean intensity of endoplasmic reticulum tracker under Salmonella bacteria was calculated. Statistical analysis was performed by an R script, quantifying infected and non-infected cells for wild-type and ΔsifA mutant cells. The dataset can be further used by researchers working with big data of endoplasmic reticulum fluorescence microscopic images, Salmonella bacterial infection images and human cancer cells.

Tobacco-Derived Lipopolysaccharide, Not Microbial Translocation, as a Potential Contributor to the Pathogenesis of Rheumatoid Arthritis

Microbial lipopolysaccharides (LPS) have been implicated in the pathogenesis of rheumatoid arthritis (RA), possibly driving a systemic inflammatory response that may trigger the development and/or exacerbation of the disease. To explore the existence of this mechanism in African RA patients, we have measured systemic levels of LPS and its surrogate, LPS-binding protein (LBP), as well as those of intestinal fatty acid-binding protein (I-FABP), pulmonary surfactant protein D (SP-D), and cotinine in serum to identify possible origins of LPS, as well as associations of these biomarkers with rheumatoid factor (RF) and anticitrullinated peptide (aCCP) autoantibodies and the DAS 28-3 clinical disease severity score. A cohort of 40 disease-modifying antirheumatic drug-naïve, black South African RA patients rated by compound disease scores and 20 healthy subjects and 10 patients with chronic obstructive pulmonary disease (COPD) as controls were included in this study. Levels of the various biomarkers and autoantibodies were measured using a combination of ELISA and immunofluorimetric and immunoturbidometric procedures. LPS levels were lowest in the RA group compared to the healthy controls (p = 0.026) and COPD patients (p = 0.017), while LBP levels were also significantly lower in RA compared to the healthy individuals (p = 0.036). Levels of I-FABP and SP-D were comparable between all three groups. Categorisation of RA patients according to tobacco usage revealed the following significant positive correlations: LBP with C-reactive protein (p = 0.0137); a trend (p = 0.073) towards an association of LBP with the DAS 28-3 disease severity score; RF-IgG antibodies with both LPS and LBP (p = 0.033 and p = 0.041, respectively); aCCP-IgG antibodies with LPS (p = 0.044); and aCCP-IgG with RF-IgM autoantibodies (p = 0.0016). The findings of this study, several of them novel, imply that tobacco products, as opposed to microbial translocation, represent a potential source of LPS in this study cohort of RA patients, again underscoring the risks posed by tobacco usage for the development and severity of RA.

Salmonella exploits HLA-B27 and host unfolded protein responses to promote intracellular replication

Objective

Salmonella enterica infections can lead to Reactive Arthritis (ReA), which can exhibit an association with human leucocyte antigen (HLA)-B*27:05, a molecule prone to misfolding and initiation of the unfolded protein response (UPR). This study examined how HLA-B*27:05 expression and the UPR affect the Salmonella life-cycle within epithelial cells.

Methods

Isogenic epithelial cell lines expressing two copies of either HLA-B*27:05 and a control HLA-B*35:01 heavy chain (HC) were generated to determine the effect on the Salmonella infection life-cycle. A cell line expressing HLA-B*27:05.HC physically linked to the light chain beta-2-microglobulin and a specific peptide (referred to as a single chain trimer, SCT) was also generated to determine the effects of HLA-B27 folding status on S. enterica life-cycle. XBP-1 venus and AMP dependent Transcription Factor (ATF6)-FLAG reporters were used to monitor UPR activation in infected cells. Triacin C was used to inhibit de novo lipid synthesis during UPR, and confocal imaging of ER tracker stained membrane allowed quantification of glibenclamide-associated membrane.

Results

S. enterica demonstrated enhanced replication with an altered cellular localisation in the presence of HLA-B*27:05.HC but not in the presence of HLA-B*27:05.SCT or HLA-B*35:01. HLA-B*27:05.HC altered the threshold for UPR induction. Salmonella activated the UPR and required XBP-1 for replication, which was associated with endoreticular membrane expansion and lipid metabolism.

Conclusions

HLA-B27 misfolding and a UPR cellular environment are associated with enhanced Salmonella replication, while Salmonella itself can activate XBP-1 and ATF6. These data provide a potential mechanism linking the life-cycle of Salmonella with the physicochemical properties of HLA-B27 and cellular events that may contribute to ReA pathogenesis. Our observations suggest that the UPR pathway maybe targeted for future therapeutic intervention.

Reactive arthritis

Reactive arthritis (ReA) is an immune-mediated seronegative arthritis that belongs to the group of spondyloarthropathies and develops after a gastrointestinal or genitourinary system infection. The condition is considered to be characterized by a triad of symptoms (conjunctivitis, arthritis and urethritis) although a constellation of other manifestations may also be present. ReA is characterized by psoriasiform dermatological manifestations that may resemble those of pustular psoriasis and, similar to guttate psoriasis, is a post-infectious entity. Also, the articular manifestations of the disorder are similar to those of psoriatic arthritis and both conditions show a correlation with HLA-B27. These facts have led several authors to suggest that there is a connection between ReA and psoriasis, listing ReA among the disorders related to psoriasis. However, the pathogenetic mechanism behind the condition is complex and poorly understood. Bacterial antigenicity, the type of host response (i.e. Th1/Th2 imbalance) and various genetic factors (i.e. HLA-B27 etc.) play an important role in the development of the disorder. It is unknown whether all the aforementioned factors are part of a mechanism that could be similar to, or share basic aspects with known psoriasis pathogenesis mechanisms.

Altered regulation of ELAVL1/HuR in HLA-B27-expressing U937 monocytic cells

OBJECTIVE

To investigate the role of HLA-B27 expression in the regulation of RNA binding protein (RBP) Embryonic Lethal Abnormal Vision (ELAV) L1/Human antigen R (HuR) expression in Salmonella-infected or LPS-stimulated human monocytic cells, since HuR is a critical regulator of the post-transcriptional fate of many genes (e.g. TNFα) important in inflammatory response.

METHODS

U937 monocytic cells were stably transfected with pSV2neo resistant vector (mock), wild type HLA-B27, or mutated HLA-B27 with amino acid substitutions in the B pocket. Cells were differentiated, infected with Salmonella enteritidis or stimulated with lipopolysaccharide. The expression levels of HuR protein and cleavage products (CP1 and CP2) were detected by Western blotting and flow cytometry. Specific inhibitors were used to study the role of PKR and p38 in HuR expression and generation of CPs. TNFα and IL-10 secretion after p38 and PKR inhibition were measured by ELISA.

RESULTS

Full length HuR is overexpressed and HuR cleavage is disturbed in U937 monocytic cells expressing HLA-B27 heavy chains (HC). Increased full length HuR expression, disturbed cleavage and reduced dependence on PKR after infection correlate with the expression of glutamic acid 45 in the B pocket that is linked to the misfolding of HLA-B27.

CONCLUSION

Results show that the expression of HLA-B27 HCs modulates the intracellular environment of U937 monocyte/macrophages by altering HuR regulation. This phenomenon is at least partly dependent on the misfolding feature of the B27 molecule. Since HuR is an important regulator of multiple genes involved in inflammatory response observations offer an explanation how HLA-B27 may modulate inflammatory response.

HLA-B27 modulates intracellular growth of Salmonella pathogenicity island 2 mutants and production of cytokines in infected monocytic U937 cells

BACKGROUND

Salmonella enterica serovar Enteritidis PT4 KS8822/88 replicates rapidly in HLA-B27-transfected human monocytic U937 cells. In this process, Salmonella pathogenicity island 2 (SPI-2) genes play a crucial role. Our previous study indicated that 118 Salmonella genes, including 8 SPI-2 genes were affected by HLA-B27 antigen during Salmonella infection of U937 cells.

METHODS/PRINCIPAL FINDINGS

To further investigate Salmonella replication in HLA-B27-positive U937 monocytic cells, two SPI-2 genes, ssaS and sscA up-regulated most during Salmonella infection of HLA-B27-transfected U937 cells, were mutated by using one-step gene disruption method. Intracellular survival and replication of the mutants in the U937 cells was compared to that of the wild type strain. Surprisingly, the two mutated strains replicated significantly more than the wild type bacteria in HLA-B27-transfected cells. Secretion of tumor necrosis factor alpha (TNF-α) and interleukin 10 (IL-10) was significantly induced during the infection of HLA-B27-transfected U937 cells with the mutants. The results indicated that the certain SPI-2 genes in wild type bacteria suppress Salmonella intracellular growth and production of cytokines in infected HLA-B27-transfected cells. HLA-B27-associated modulation of Salmonella SPI-2 genes and cytokine production may have importance in the persistent infection of the bacteria and the pathogenesis of reactive arthritis.

CONCLUSIONS

The study provides evidence that certain virulence factors of pathogens can reduce the intracellular growth in the host cells. We suggest that the limiting intracellular growth might be a strategy for persistence of bacteria in host cells, keeping a balance between pathogenic growth and pathogenesis.

Microarray analysis of response of Salmonella during infection of HLA-B27- transfected human macrophage-like U937 cells

BACKGROUND

Human leukocyte antigen (HLA)-B27 is strongly associated with the development of reactive arthritis (ReA) in humans after salmonellosis. Human monocytic U937 cells transfected with HLA-B27 are less able to eliminate intracellular Salmonella enterica serovar Enteritidis than those transfected with control HLA antigens (e.g. HLA-A2). To investigate further the mechanisms by which HLA-B27-transfected cells allow increased replication of these bacteria, a DNA-based microarray was used for comparative genomic analysis of S. Enteritidis grown in HLA-B27- or HLA-A2-transfected cells. The microarray consisted of 5080 oligonucleotides from different serovars of Salmonella including S. Enteritidis PT4-specific genes. Bacterial RNA was isolated from the infected HLA-B27- or HLA-A2-transfected cells, reverse-transcribed to cDNA, and hybridized with the oligonucleotides on the microarrays. Some microarray results were confirmed by RT-PCR.

RESULTS

When gene expression was compared between Salmonella grown in HLA-B27 cells and in HLA-A2 cells, 118 of the 4610 S. Enteritidis-related genes differed in expression at 8 h after infection, but no significant difference was detectable at 2 h after infection. These differentially expressed genes are mainly involved in Salmonella virulence, DNA replication, energy conversion and metabolism, and uptake and metabolism of nutrient substances, etc. The difference suggests HLA-B27-dependent modulation of Salmonella gene expression, resulting in increased Salmonella replication in HLA-B27-positive cells. Among the up-regulated genes were those located in Salmonella pathogenicity island (SPI)-2, which play a central role in intracellular survival and replication of Salmonella.

CONCLUSIONS

This is the first report to show the regulation of Salmonella gene expression by HLA-B27 during infection of host cells. This regulation probably leads to increased Salmonella survival and replication in HLA-B27-positive cells. SPI-2 genes seem to contribute significantly to the increased replication.

Cellulitis and septic arthritis caused by Campylobacter fetus and Campylobacter jejuni: report of 2 cases and review of the literature

Bacteremia caused by gram-negative bacteria occasionally causes soft tissue infections, including cellulitis and septic arthritis. We describe 1 patient each with Campylobacter fetus cellulitis and septic arthritis and review the world literature with regard to C. fetus and C. jejuni infections at these sites. Altogether, 14 patients with cellulitis (12 due to C. fetus and 2 due to C. jejuni) and 20 patients with septic arthritis (15 due to C. fetus and 4 caused by C. jejuni) have been described. Most infections, particularly those causing cellulitis, are found in elderly men with underlying systemic disease. Most patients are febrile but less than half manifest a leukocytosis. There were only 3 deaths in this series of 33 patients. The newer macrolides, including azithromycin and clarithromycin, are considered the drugs of choice, particularly with C. jejuni, while soft tissue infections caused by C. fetus respond nicely to many beta-lactams, particularly to cephalosporins and carbapenems, as well as to macrolides and quinolones.

Reactive arthritis

ReA consists of sterile axial or peripheral articular inflammation,enthesitis, and extra-articular manifestations. Most patients are HLA-B27 positive, although determining the B27 status of an individual patient is irrelevant. Exposure to specific bacterial antigens is usually the inciting factor. Diagnosis usually can be made by clinical examination and history. The current standard therapy is NSAIDs and physiotherapy, but molecular biologic treatment may ultimately become the mainstay in recalcitrant and severe ReA.

Clinical presentations of chlamydial and non-chlamydial reactive arthritis

The aim of this study was to investigate the triggering micro-organisms and the clinical as well as laboratory differences between Chlamydial and non-chlamydial reactive arthritis (ReA) in a prospective study on 98 patients with acute/subacute arthritis. An inciting organism was found in 42 patients. Eighteen of these were chlamydial. Fifty-seven percent of all ReA patients were carriers for HLA-B27, which increased to 67% in the chlamydial group. Chlamydial ReA patients had more urethritis (P<0.05) with a longer period between arthritis and inciting infection, significantly lower CRP levels, and involved joint counts (P<0.05). Additionally, sacroiliitis was more frequent besides extra-articular manifestations in chlamydial ReA group. This study shows that chlamydial ReA differs in some points from non-chlamydial ReA, which in turn may affect the evaluation of an arthritic patient. ReA due to chlamydia more frequently encompasses a monoarticular or oligoarticular clinical picture with predominant distal extremity involvement. Non-chlamydial ReA presents higher joint counts and may involve upper extremity joints.

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.

HLA-B27 modulates nuclear factor kappaB activation in human monocytic cells exposed to lipopolysaccharide

OBJECTIVE

To study whether HLA-B27 modifies some key factors controlling inflammatory responses on lipopolysaccharide (LPS) stimulation in human monocytic cells.

METHODS

U937 human monocytic cells were stably transfected with either HLA-B27 genomic DNA, HLA-B27 complementary DNA, HLA-A2 genomic DNA, or with the resistant vector pSV2neo (mock) alone. The cells were stimulated with LPS. Electrophoretic mobility shift assay was performed to determine nuclear factor kappaB (NF-kappaB) and heat-shock factor 1 activities, Western blotting was performed to detect the expressions of inhibitory kappaBalpha (IkappaBalpha) and heat-shock proteins (HSPs), and enzyme-linked immunosorbent assay was performed to measure tumor necrosis factor alpha (TNFalpha) secretion.

RESULTS

The expression of HLA-B27 modulated the response to LPS in U937 human monocytic cells. Stimulation with LPS led to faster degradation of IkappaBalpha regulatory proteins, accompanied by faster and prolonged activation of NF-kappaB in HLA-B27-expressing cells compared with HLA-A2 and mock transfectants. The secretion of TNFalpha upon LPS stimulation correlated well with the activation of NF-kappaB. No activation of the heat-shock response was observed.

CONCLUSION

Our data indicate that HLA-B27 has effects on host responses to LPS that are unrelated to antigen presentation. Two crucial events in the development of arthritis, the activation of NF-kappaB and the secretion of TNFalpha, were found to be enhanced in HLA-B27-expressing cells upon LPS stimulation. Because LPS is known to be present in the inflamed joints of patients with reactive arthritis (ReA), the enhanced inflammatory response of HLA-B27-positive cells upon LPS stimulation offers an attractive explanation for the role of HLA-B27 in the development of ReA.

Invasion of Salmonella into human intestinal epithelial cells is modulated by HLA-B27

OBJECTIVE

To investigate the influence of the major histocompatibility complex (MHC) class I molecule HLA-B27 on (i) the invasion of Salmonella and Yersinia into human intestinal epithelial cells, (ii) the survival of intracellular Salmonella in these cells, and (iii) the production of certain inflammatory cytokines by the cells after Salmonella infection.

METHODS

The human intestinal epithelial cell line Henle-407 was transfected with HLA-B27 DNA. These cells and HLA-B27-negative control cells were infected with Salmonella or Yersinia, and viable intracellular bacteria were determined as colony-forming units. Cytokine production was assayed with ELISA.

RESULTS

Salmonella invaded HLA-B27-positive Henle cells in higher numbers than HLA-B27-negative control cells. However, HLA-B27 did not affect the invasion of Yersinia or the survival of the intracellular bacteria in these intestinal epithelial cells. Salmonella infection induced production of interleukin-8 (IL-8), IL-6 and monocyte chemotactic protein 1 (MCP-1) by Henle cells that was not affected by HLA-B27 in a specific way.

CONCLUSIONS

These findings suggest that HLA-B27 enhances the invasion of Salmonella into intestinal epithelial cells. The interaction between bacteria and intestinal epithelial cells plays an important role during the early phases of ReA. HLA-B27-linked modulation of Salmonella invasion may lead to an increased load of Salmonella in intestinal tissue and thus increased susceptibility to reactive arthritis.

Infection of synovial fibroblasts in culture by Yersinia enterocolitica and Salmonella enterica serovar Enteritidis: ultrastructural investigation with respect to the pathogenesis of reactive arthritis

Synovial fibroblasts were infected with Yersinia enterocolitica or Salmonella enterica serovar Enteritidis and analyzed by electron microscopy and fluorescence in situ hybridization. Intracellular bacterial replication was followed by degradation leading to "ghosts" possessing lipopolysaccharides but not DNA. However, single bacteria survived for more than 2 weeks. Therefore, transient intra-articular infection might be the missing link between initial intestinal infection and late synovial inflammation in the pathogenesis of reactive arthritis.

Insights into the Role of Infection in the Spondyloarthropathies

Certain infections play an important role in the pathogenesis of the human leukocyte antigen (HLA)-B27-associated reactive arthritis. Whether infections play a role in other forms of spondyloarthropathies is not as clear. The role of HLA-B27 as an antigen-presenting molecule is important in the pathogenesis of these diseases. Recent evidence has been obtained indicating that this molecule may have other functions unrelated to antigen-presentation in the interaction of reactive arthritis-triggering microbes and host. This paper reviews the recent studies on the role of infection in the spondyloarthropathies.

Frequency of triggering bacteria in patients with reactive arthritis and undifferentiated oligoarthritis and the relative importance of the tests used for diagnosis

OBJECTIVE

Reactive arthritis (ReA) triggered by Chlamydia trachomatis or enteric bacteria such as yersinia, salmonella, Campylobacter jejuni, or shigella is an important differential diagnosis in patients presenting with the clinical picture of an undifferentiated oligoarthritis (UOA). This study was undertaken to evaluate the best diagnostic approach.

PATIENTS AND METHODS

52 patients with ReA, defined by arthritis and a symptomatic preceding infection of the gut or the urogenital tract, and 74 patients with possible ReA, defined by oligoarthritis without a preceding symptomatic infection and after exclusion of other diagnoses (UOA), were studied. The following diagnostic tests were applied for the identification of the triggering bacterium: for yersinia induced ReA-stool culture, enzyme immunoassay (EIA), and Widal's agglutination test for detection of antibodies to yersinia; for salmonella or campylobacter induced ReA-stool culture, EIA for the detection of antibodies to salmonella and Campylobacter jejuni; for infections with shigella-stool culture; for infections with Chlamydia trachomatis-culture of the urogenital tract, microimmunofluorescence and immunoperoxidase assay for the detection of antibodies to Chlamydia trachomatis.

RESULTS

A causative pathogen was identified in 29/52 (56%) of all patients with ReA. In 17 (52%) of the patients with enteric ReA one of the enteric bacteria was identified: salmonella in 11/33 (33%) and yersinia in 6/33 (18%). Chlamydia trachomatis was the causative pathogen in 12/19 (63%) of the patients with urogenic ReA. In patients with the clinical picture of UOA a specific triggering bacterium was also identified in 35/74 (47%) patients: yersinia in 14/74 (19%), salmonella in 9/74 (12%), and Chlamydia trachomatis in 12/74 (16%).

CONCLUSIONS

Chlamydia trachomatis, yersinia, and salmonella can be identified as the causative pathogen in about 50% of patients with probable or possible ReA if the appropriate tests are used.

Outbreak of Salmonella braenderup gastroenteritis due to contaminated meat pies: clinical and molecular epidemiology

OBJECTIVES

To determine the epidemiologic, clinical and molecular characteristics of an outbreak of severe gastroenteritis due to the ingestion of meat pies highly contaminated with Salmonella braenderup.

METHODS

In October 1993, we observed an outbreak of Salmonella braenderup gastroenteritis that occurred in the Lausanne area, Canton de Vaud, Switzerland. Cultures of suspected food products, of samples at the incriminated food factory and from workers, as well as a case-control study, were used to determine the source of the epidemics. Ribotyping of representative Salmonella braenderup strains was performed to define the molecular epidemiology. The clinical characteristics of this infection were determined by using a standardized interview performed during and 6 months after the outbreak in 156 of 215 identified patients.

RESULTS

The outbreak resulted from the ingestion of pies, heavily contaminated (> 106 CFU/g) with a strain of Salmonella braenderup. The contamination was due to mishandling and recycling of jelly poured on top of the products. According to its ribotype and plasmid characteristics, this strain had not been isolated previously in Switzerland. Ten of the 24 workers of the incriminated food factory were shedding the epidemic strain in their stools, and one of them reported gastroenteritis 3 weeks before the beginning of the outbreak. The estimated attack rate in the exposed population was 7.5%. The median incubation time was 18 h. Among 127 adult patients studied, 98% had diarrhea, 95% abdominal pain, 74% fever > or = 38.5 degrees C, 69% nausea and 35% vomiting. One patient developed prosthetic valve endocarditis, and one reactive arthritis. Long-term complications were not identified, although 12 patients complained of irritable bowel syndrome and 24 of unusual asthenia lasting for more than 6 weeks after infection. Children had more severe signs and symptoms compared to adults, and six of 29 needed hospitalization.

CONCLUSIONS

This study showed that ingestion of food highly contaminated with Salmonella braenderup resulted in severe but typical gastroenteritis and indicated mishandling of food during manufacture as the cause of this outbreak.

No benefit of long-term ciprofloxacin treatment in patients with reactive arthritis and undifferentiated oligoarthritis: a three-month, multicenter, double-blind, randomized, placebo-controlled study

OBJECTIVE

To investigate the effect of long-term antibiotic treatment in patients with reactive arthritis (ReA) and undifferentiated oligoarthritis.

METHODS

One hundred twenty-six patients were treated with ciprofloxacin (500 mg twice a day) or placebo for 3 months, in a double-blind, randomized study. Of these patients, 104 (48 treated with ciprofloxacin and 56 treated with placebo) were valid for clinical evaluation: 55 were diagnosed as having ReA with a preceding symptomatic urogenic or enteric infection and 49 as having undifferentiated oligoarthritis. These 2 groups were randomized separately. The triggering bacterium was sought by serology and/or culture. The percentage of patients in remission after 3 months of treatment was chosen as the primary efficacy parameter.

RESULTS

A triggering bacterium could be identified in 52 patients (50%): Chlamydia trachomatis in 13, Yersinia in 14, and Salmonella in 25. No patient was positive for Campylobacter jejuni or for Shigella. No difference in outcome was found between treatment with ciprofloxacin or placebo in the whole group or in subgroups of patients with ReA or undifferentiated oligoarthritis. No difference was seen in patients with a disease duration <3 months. Ciprofloxacin was not effective in Yersinia- or Salmonella-induced arthritis but seemed to be better than placebo in Chlamydia-induced arthritis. This difference was not significant, however, which might be due to the small sample size.

CONCLUSION

Long-term treatment of ReA with ciprofloxacin is not effective; however, it might be useful in the subgroup of patients who have Chlamydia-induced arthritis. This has to be proven in a bigger study focusing on patients with Chlamydia-induced arthritis.

Bowel inflammation and the spondyloarthropathies

The concept of spondyloarthropathies gathers together a group of chronic diseases in which not only the locomotor system is involved but also other organs, especially the gastrointestinal tract. In humans, ileocolonoscopic studies demonstrated the presence of inflammatory gut lesions in all the diseases in the spondyloarthropathy group; their presence varied in the different diseases between 20% and 70%. The inflammation could be related to specific disease features in the spondyloarthropathies. Further research supports the hypothesis of subclinical inflammatory bowel disease in some patients with spondyloarthropathy, in which the locomotor inflammation was the only clinical manifestation. The link between gut inflammation and arthropathy has also been demonstrated in animal models, notably the human leukocyte antigen B27 transgenic rats. The temporal relationship between activity and severity of colonic involvement and flares of peripheral arthritis directs treatment of choice. For all forms of enterogenic arthropathies, nonsteroidal anti-inflammatory drugs remain the acute treatment form. Caution is in order, however, because of their possible harmful effects on intestinal integrity, permeability, and even on gut inflammation.

Persistence of Yersinia antigens in peripheral blood cells from patients with Yersinia enterocolitica O:3 infection with or without reactive arthritis

OBJECTIVE

To assess the persistence of bacterial antigens in peripheral blood cells from patients with Yersinia enterocolitica O:3-triggered reactive arthritis (ReA).

METHODS

Peripheral blood samples were obtained from 20 patients with Y. enterocolitica O:3 infection (11 with ReA and 9 without). These samples were studied by immunochemical techniques for the presence of Yersinia antigens at the beginning of infection and up to 4 years thereafter. Synovial fluid samples from 6 of the 11 ReA patients were also studied.

RESULTS

The Yersinia antigens lipopolysaccharide and heat-shock protein (HSP) were detected in peripheral blood mononuclear cells and polymorphonuclear phagocytes from all patients studied at the early phase of the disease. They were also found in the synovial fluid cells of patients with Yersinia-triggered ReA. At 4 years after the onset of infection, these bacterial antigens were still detected in the peripheral blood cells of most of the ReA patients studied.

CONCLUSION

This study has, for the first time, directly demonstrated that bacterial antigens persist for a long time in patients who develop ReA after Y. enterocolitica O:3 infection. The finding of bacterial HSP in synovial fluid cells could provide a link to the pathogenesis of ReA, since T cell responses of synovial cells have been shown to be directed against that structure. A close similarity between the bacterial and host HSP might contribute to the development of the relatively common, chronic form of this complication.

Characterization of the synovial T cell response to various recombinant Yersinia antigens in Yersinia enterocolitica-triggered reactive arthritis. Heat-shock protein 60 drives a major immune response

OBJECTIVE

In Yersinia enterocolitica-triggered reactive arthritis (Yersinia ReA), the synovial T cell response is primarily directed against bacterial components, which are mostly unknown. This study was performed to investigate the synovial proliferative T cell response to a panel of recombinant Yersinia antigens in patients with Yersinia ReA and in controls.

METHODS

Synovial fluid mononuclear cells (SFMC) were obtained from 4 patients with Yersinia ReA and from 14 patients with arthritides of different etiology. SFMC were stimulated with 5 recombinant Yersinia antigens (the 19-kd urease beta subunit, 13-kd ribosomal L23 protein, 32-kd ribosomal L2 protein, 18-kd outer membrane protein H, and Y. enterocolitica heat-shock protein 60 [hsp60]), and with human, Chlamydia trachomatis, and Borrelia burgdorferi hsp60. Three T cell clones specific for Y. enterocolitica hsp60 were generated from 1 patient with Yersinia ReA. Antigen-induced cytokine release was measured by enzyme-linked immunosorbent assay.

RESULTS

SFMC from all 4 patients with Yersinia ReA responded to each of the Yersinia antigens except the 13-kd protein. These antigens were also recognized by SFMC from a subgroup of patients with undifferentiated arthritis (n = 4), but not by SFMC from other patients with arthritis of different etiology (n = 10). Y. enterocolitica hsp60 induced the strongest proliferative response in all cases. Two types of hsp60-reactive T cell clones could be obtained. One clone responded to all hsp60 variants, including the human variant, and showed a type 2 T helper (Th2)-like cytokine-secretion pattern. In contrast, another clone with specificity for the bacterial hsp60 proteins, but not the human equivalent, reacted with a more Th1-like pattern.

CONCLUSION

In Y. enterocolitica-triggered ReA, at least 4 immunodominant T cell antigens exist, which might be used in lymphocyte proliferation assays to identify patients with Yersinia ReA. The hsp60 is a strong antigen, inducing both bacteria-specific and potentially autoreactive CD4+ T cells of both the Th1 and Th2 type.

Enhanced jejunal production of antibodies to Klebsiella and other Enterobacteria in patients with ankylosing spondylitis and rheumatoid arthritis

OBJECTIVE

To measure gut immunity directly in jejunal fluid in patients with ankylosing spondylitis (AS) and rheumatoid arthritis (RA).

METHODS

Antibodies against three different Enterobacterias were measured in jejunal perfusion fluids (collected by a double balloon perfusion device) of 19 patients with AS, 14 patients with RA, and 22 healthy controls using enzyme linked immunosorbent assay.

RESULTS

The AS patients had significantly increased jejunal fluid concentrations of IgM, IgG, and IgA class antibodies against Klebsiella pneumoniae, and IgM and IgA class antibodies against Escherichia coli and Proteus mirabilis compared with healthy controls. When compared with the patients with RA, the AS patients had higher concentrations of IgA and IgG class antibodies only against K pneumoniae. The RA patients had higher IgM class antibody concentrations against all three studied Enterobacterias, when compared with the healthy controls, suggesting an enhanced mucosal immune response in these patients. A three month treatment with sulphasalazine did not decrease enterobacterial antibody concentrations in the 10 patients with AS.

CONCLUSION

There is strong direct evidence for an abnormal mucosal humoral immune response particularly to K pneumoniae in patients with AS.

HLA-B27 modulates intracellular survival of Salmonella enteritidis in human monocytic cells

Human major histocompatibility complex class I allele HLA-B27 is associated with a group of diseases called spondyloarthropathies. In reactive arthritis (ReA), the disease is triggered by certain infections, e.g. gastroenteritis caused by Salmonella. The host/microbe interaction is abnormal in susceptible individuals leading to inefficient elimination of arthritis-triggering bacteria, fragments of them, or both, after the initial infection. Using transfected human monocytic U937 cell lines, we demonstrate that the expression of the HLA-B27 antigen does not influence the uptake of S. enteritidis into U937 cells in vitro. Interestingly, HLA-B27 remarkably impairs the elimination of S. enteritidis within the HLA-B27 transfected U937 cells. The impaired elimination of ReA-triggering microbes by HLA-B27+ monocytes may offer an explanation for the persistence of ReA-triggering microbes in susceptible HLA-B27+ individuals. This modulation of the host/microbe interaction by HLA-B27 may have an important role in the pathogenesis of ReA.

Induction of alternative splicing of HLA-B27 by bacterial invasion

OBJECTIVE

Alternative splicing of certain class I major histocompatibility complex pre-messenger RNA (pre-mRNA) is known to lead to generation of a cell-free soluble protein analog. This study was undertaken to examine whether this process occurs with HLA-B27, whether the process is modified by arthritis-causing bacteria, and whether the assembly of the soluble molecules follows the same pathway as the integral parent molecules.

METHODS

Alternative splicing of pre-mRNA was analyzed by reverse transcriptase-polymerase chain reaction, and assembly of soluble HLA-B27 by immunoprecipitation followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography.

RESULTS

There was alternative splicing of the pre-mRNA of HLA-B27. The process could be amplified by invasion with Salmonella or Yersinia bacteria. The soluble HLA-B27 was assembled in a pathway similar to that of the parent molecule.

CONCLUSION

The association between arthritis-causing bacteria and HLA-B27 positive cells is a complex event. Soluble HLA-B27 is a potential key player.

Host-microbe interaction in HLA-B27-associated diseases

The mechanisms leading to the development of HLA-B27-associated diseases, spondyloarthropathies, are unknown. One of them, reactive arthritis, is clearly caused by an infection, and joint inflammation develops soon after or during an infection elsewhere in the body. In other forms of spondyloarthropathies, such as ankylosing spondylitis, association with infection is suggested but it is not as clear. Pathogenetic mechanisms of reactive arthritis are a focus of great interest as causative infections and strong genetic association are known. How HLA-B27 determines the appearance of joint complications after certain infections is not clear. Several theories have been proposed to explain the association, and they usually include the idea that interaction between microbe and host is abnormal and inefficient in HLA-B27-positive subjects in whom reactive arthritis develops.

High frequency of Yersinia antibodies in healthy populations in Finland and Germany

Sera from 94 healthy Finnish and 100 healthy German blood donors were studied for Yersinia enterocolitica antibodies by two different techniques, enzyme immunoassay and immunoblotting, to compare the frequency of Yersinia infections in Finnish and German populations. The prevalence of Yersinia antibodies in Finland (19% and 31% by enzyme immunoassay and immunoblotting, respectively) and in Germany (33%, 43%) is relatively high and may indicate many subclinical Yersinia infections in healthy populations. Postinfectious complications, such as reactive arthritis, may follow also such subclinical infection; sensitive serological tests are important in their diagnosis.

Bacterial gastroenteritis among hospitalized patients in a Danish County, 1991-93

BACKGROUND

Denmark has in recent years experienced an increase in the number of bacterial gastrointestinal infections.

METHODS

We have reviewed patients hospitalized with culture-confirmed bacterial gastroenteritis in Roskilde County during 1991-93.

RESULTS

Two hundred and seven patients were included; 68 were children (< 15 years). The microorganism isolated was Salmonella in 61% of the cases, Campylobacter in 20% and Yersinia enterocolitica in 13%. Ninety-three per cent of the patients had diarrhea, 74% had fever (> 38 degrees C), and 66% abdominal pain. Blood in stools was most frequent in patients infected with Campylobacter. Leukocytosis was rare. Twenty-four patients had bacteremia. Reactive arthritis occurred in 4.8%. Three patients died, all infected with zoonotic Salmonella types. Three stool cultures were made for 115 patients, and in 73% all 3 cultures were positive.

CONCLUSIONS

Bacterial gastroenteritis requiring hospitalization affects mainly children and young adults. Infections due to zoonotic Salmonella types were more severe than Campylobacter and Y. enterocolitica gastroenteritis. It seems necessary to make at least three stool cultures to secure a bacteriologic diagnosis.

Spondylarthropathies: from gut to target organs

Recent studies strongly support the concept that gut and joint inflammation are closely related. Progress also has been made in identifying individual mechanisms that contribute to the pathogenesis of joint disease in IBD and in undifferentiated SpAs. However, the interrelationship of these mechanisms that result in chronic disease manifestations at a site distant from the initiating event remain to be elucidated. The local absence of homing molecule receptors in the gut wall combined with an expression of these receptors in target organs can be responsible for the transformation of the synovial membrane and/or the enthesis into an aberrant tertiary lymphoid organ of the gut.

Diagnostic value of synovial fluid analysis in children with reactive arthritis

We report on three children with pauciarticular arthritis in whom the clinical picture and serology were compatible with both arthritis reactive to infection with Yersinia or Salmonella and with Lyme arthritis. Results of analysis of synovial fluid by polymerase chain reaction for enterobacterial or borrelial sequences were negative. Immunofluorescence with specific antibodies revealed the presence of amorphous enterobacterial antigens in synovial fluid cells. Since this staining did not reveal enterobacterial morphology, we infected synovial fluid cells of two children with juvenile rheumatoid arthritis in vitro with Yersinia or Salmonella. After 24 h typical rods were observed, but after about 1 week amorphous antigen similar to what had been found in the three patients was seen. In cases of reactive arthritis with ambiguous results of serological testing the diagnosis may be confirmed by demonstration of enterobacterial antigens in synovial fluid.

IgA1 and IgA2 subclass antibodies against Klebsiella pneumoniae in the sera of patients with peripheral and axial types of ankylosing spondylitis

OBJECTIVE

To study further the Klebsiella specific serum antibody response in patients with axial and peripheral types of ankylosing spondylitis (AS).

METHODS

IgA1 and IgA2 subclass antibodies to Klebsiella pneumoniae were measured by enzyme linked immunosorbent assay in the sera of 171 patients with axial or peripheral type AS, and in sera of 100 healthy controls. The effect of 26 weeks of sulphasalazine treatment on the antibody levels in the two types of AS was also analysed.

RESULTS

K pneumoniae specific antibody levels of both IgA1 and IgA2 subclasses were increased in the sera of patients with AS compared with healthy controls. The increased levels were present in patients with axial and with peripheral AS, and there were no statistically significant differences in the antibody levels between these two groups. Sulphasalazine treatment decreased the Klebsiella specific antibody level of IgA1 subclass in patients with axial AS, but there were no statistically significant changes in the IgA2 subclass, or in the patients with peripheral type AS.

CONCLUSIONS

These results agree with earlier published findings suggesting that IgA (especially Klebsiella specific IgA) may have a role in the pathogenetic mechanisms of both peripheral and axial types of AS. In addition, it seems that both IgA1 and IgA2 subclasses are involved in the disease process.

Amplification of plasmid and chromosome Chlamydia DNA in synovial fluid of patients with reactive arthritis and undifferentiated seronegative oligoarthropathies

OBJECTIVE

To investigate the hypothesis that whole bacteria might be found in the joints of patients with Chlamydia-associated reactive arthritis.

METHODS

The presence of 2 plasmid- and 2 chromosome-specific sequences of Chlamydia DNA was investigated by amplification with the polymerase chain reaction, in synovial fluid (SF) samples from 71 patients with various arthropathies.

RESULTS

Chlamydia DNA was found in SF samples from 22 patients.

CONCLUSION

Whole chlamydiae are likely present in the SF of patients with Chlamydia-associated reactive arthritis.

Yersinia-specific antibodies in serum and synovial fluid in patients with Yersinia triggered reactive arthritis

OBJECTIVES

To further evaluate the role of bacterial antigens in triggering inflammation in the joint in patients with reactive arthritis by studying local antibody synthesis in the joint.

METHODS

Yersinia-specific antibodies in paired serum and synovial fluid samples from 29 patients with yersinia triggered reactive arthritis were studied using an enzyme linked immunosorbent assay (ELISA), an inhibition ELISA with six monoclonal antibodies against lipopolysaccharide or released proteins of yersinia and immunoblotting. Antibodies of IgM, IgG and IgA classes, as well as antibodies of IgA subclasses and those containing secretory component were measured against the lipopolysaccharide and the sodium dodecyl sulphate extract of whole Yersinia enterocolitica O:3 bacteria.

RESULTS

It was shown that yersinia-specific antibodies, as well as antibodies against other microbial antigens (rubella, measles, Bordetella pertussis, tetanus toxoid and Candida albicans) in synovial fluid mirror those in serum by concentration, by specificity and by distribution in classes and subclasses.

CONCLUSION

These results do not suggest any strong local antibody production, but indicate that the majority of yersinia antibodies in the synovial fluid are derived from the circulation.

Rheumatic manifestations of Campylobacter jejuni and C. fetus infections in adults

Reports of the rheumatic manifestations of Campylobacter jejuni and C. fetus infections in adults are reviewed in order to determine the most common presentations and which individuals are at risk for rheumatic disease. Relevant English-language articles were identified through a Medline search and from bibliographies of identified articles. 105 articles were reviewed in detail. 29 cases of reactive arthritis or Reiter's syndrome following Campylobacter jejuni enteritis were identified. The knee is the most commonly involved joint and an average of 3.2 joints were involved in affected persons. HL-A B27 positive patients are more frequently affected and have higher erythrocyte sedimentation rates than HL-A B27 negative patients. Eight cases of septic arthritis and 4 cases of osteomyelitis caused by C. fetus or C. jejuni were identified, and these cases generally occurred in compromised hosts or in diseased joints.

The socio-economic impact of human Salmonella enteritidis infection

Recent government and public concern about the recorded increase in human salmonellosis in the UK and abroad has stimulated investigations of both the causes and consequences of these infections. This paper discusses the framework for economic analysis of food-borne disease and problems associated with the estimation of costs. A brief review of the literature in this area is given and the results of a national study of the costs of human salmonellosis in England and Wales are presented and used to estimate the likely costs of S. enteritidis infection.

Group F beta-hemolytic streptococcus, tonsillitis and myocarditis

A case of tonsillitis and myocarditis is reported, where the only positive microbiological finding was a throat swab growing group F beta-hemolytic streptococci. The patient made an uneventful recovery after treatment with benzylpenicillin and clindamycin.

Antibody response against 26 and 46 kilodalton released proteins of yersinia in yersinia triggered reactive arthritis

Using an inhibition enzyme linked immunosorbent assay (ELISA) the serum antibody responses against released proteins of yersinia of molecular weights 26 and 46 kilodaltons were studied in 37 patients with and in 21 patients without reactive arthritis following yersinia infection. Although no difference was seen for the 46 kilodalton released protein, patients with yersinia triggered reactive arthritis had higher levels of antibodies against the 26 kilodalton released protein at the beginning of the disease than patients with uncomplicated yersiniosis. This may indicate an increased production of this protein in the early infection leading to poorer phagocytosis of the bacteria and thereby to the persistence of yersinia organisms within the arthritic host.

Salmonella-triggered reactive arthritis

Clinical significance of Salmonella-triggered reactive arthritis is rising, because the frequency of Salmonella infections is increasing all over the world. In this study reports on Salmonella-triggered reactive arthritis have been reviewed. A summary of clinical, epidemiological and laboratory data, as well as triggering serotypes, is presented. Diagnostic and therapeutic aspects are also discussed.