The infectious etiology of rheumatoid arthritis. New considerations

Ethanol extract of Ziziphus nummularia ameliorates formaldehyde-induced arthritis in rats by regulating oxidative stress biomarkers and haematological profile

BACKGROUND

Rheumatoid arthritis is an autoimmune inflammatory disorder that mainly affects bone and cartilage architecture. The continuous use of NSAIDs and DMARDs is associated with severe toxic effects. Therefore, the current study was designed to scrutinize herb-based therapy for the treatment of RA.

AIM

To evaluate the anti-arthritic activity of ethanol extract of Ziziphus nummularia using formaldehyde-induced arthritic model in rats and elucidate the possible mechanism for anti-arthritic activity.

MATERIALS AND METHODS

Anti-arthritic activity of ETZN was studied at three oral doses, i.e., 200, 400, and 600 mg/kg. Selected doses were studied using various clinical parameters viz. paw volume, inflammatory index, motility test, stair test, anti-nociceptive efficacy, walking track analysis, and motor activity) from day 1 to day 10. On the last day, the animals were killed for the evaluation of hematological parameters, oxidative stress biomarkers, and histological and radiographic studies of the hind paw.

RESULTS

Treatment with ETZN 400 mg/kg and 600 mg/kg markedly elicited a significant reduction in paw volume, inflammatory index, and nociceptive action compared to diseased animals. Furthermore, the anti-inflammatory activity was confirmed by increased latency of pain threshold in thermal and mechanical algesia models. The anti-arthritic activity is mainly attributed to a reduction in oxidative stress biomarkers as well as restoration of haematological profile in treated animals when compared to diseased animals. Lastly, the anti-arthritic potential was confirmed by histological and radiological analysis which revealed a marked reduction in inflammatory cells and bone destruction as compared to diseased animals.

CONCLUSION

The study revealed that ETZN exhibits significant anti-arthritic activity via modulation of oxidative stress biomarkers, restoration of hematological profile, and reduction in bone erosion.

J. Claude Bennett, MD: Scholar, Physician, and Leader

Dr Claude Bennett provided local, national, and international leadership in rheumatology when it was developing as a subspecialty of internal medicine. His early contributions included work in helping to understand at the molecular level how antibodies are formed. Under his leadership, UAB grew into a nationally respected institution known for its high-quality clinical care, impactful research, and outstanding training programs. His many contributions have had a lasting effect on the fields of rheumatology, medicine, and immunology. Throughout his career, he served as a role model and was widely respected for his wise advice and superb mentorship.

Etiology and Risk Factors for Rheumatoid Arthritis: A State-of-the-Art Review

Rheumatoid arthritis (RA) is the most common systemic inflammatory rheumatic disease. It is associated with significant burden at the patient and societal level. Extensive efforts have been devoted to identifying a potential cause for the development of RA. Epidemiological studies have thoroughly investigated the association of several factors with the risk and course of RA. Although a precise etiology remains elusive, the current understanding is that RA is a multifactorial disease, wherein complex interactions between host and environmental factors determine the overall risk of disease susceptibility, persistence and severity. Risk factors related to the host that have been associated with RA development may be divided into genetic; epigenetic; hormonal, reproductive and neuroendocrine; and comorbid host factors. In turn, environmental risk factors include smoking and other airborne exposures; microbiota and infectious agents; diet; and socioeconomic factors. In the present narrative review, aimed at clinicians and researchers in the field of RA, we provide a state-of-the-art overview of the current knowledge on this topic, focusing on recent progresses that have improved our comprehension of disease risk and development.

Toxoplasmosis seroprevalence in rheumatoid arthritis patients: A systematic review and meta-analysis

BACKGROUND

Toxoplasmosis is a cosmopolitan infection caused by an intracellular obligatory protozoan, Toxoplasma gondii. Infection to this parasite in immunocompetent patients is usually asymptomatic, but today it is believed that the infection can be a risk factor for a variety of diseases, including rheumatoid arthritis (RA). RA is an autoimmune disease and the most common type of inflammatory arthritis that is a major cause of disability. The aim of this systematic review and meta-analysis was to address the association between RA and toxoplasmosis in light of the available research.

METHODS

Based on the keywords, a systematic search of eight databases was conducted to retrieve the relevant English-language articles. Then, the studies were screened based on the inclusion and exclusion criteria. The random effect model was used to calculate the odds ratio (OR) using forest plot with 95% confidence interval (CI).

RESULTS

Overall, 4168 Individual, extracted from 9 articles were included for systematic review evaluation, with 1369 RA patients (46% positive toxoplasmosis) and 2799 individuals as controls (21% positive toxoplasmosis). Then, eight articles (10 datasets) were used for meta-analysis (1244 rheumatoid arthritis patients and 2799 controls). By random effect model, the combined OR was 3.30 (95% CI: 2.05 to 5.30) with P < 0.0001.

CONCLUSION

Although toxoplasmosis could be considered as a potential risk factor for rheumatoid arthritis, more and better quality studies are needed to determine the effect of T. gondii infection on induction or exacerbation of RA. Our study was registered at the International Prospective Register of Systematic Reviews (PROSPERO; code: CRD42017069384).

Therapeutic Applications of Rose Hips from Different Rosa Species

Rosa species, rose hips, are widespread wild plants that have been traditionally used as medicinal compounds for the treatment of a wide variety of diseases. The therapeutic potential of these plants is based on its antioxidant effects caused by or associated with its phytochemical composition, which includes ascorbic acid, phenolic compounds and healthy fatty acids among others. Over the last few years, medicinal interest in rose hips has increased as a consequence of recent research that has studied its potential application as a treatment for several diseases including skin disorders, hepatotoxicity, renal disturbances, diarrhoea, inflammatory disorders, arthritis, diabetes, hyperlipidaemia, obesity and cancer. In this review, the role of different species of Rosa in the prevention of treatment of various disorders related to oxidative stress, is examined, focusing on new therapeutic approaches from a molecular point of view.

In vivo anti-arthritic efficacy of Camellia sinensis (L.) in collagen induced arthritis model

BACKGROUND

Rheumatoid arthritis (RA), an autoimmune inflammatory disorder with synovial hyperplasia, destruction of cartilage, bone damage is often associated with risk of infections. Such risk could be attributed towards usage of immunosuppressive agents. Thus, the present study was undertaken to evaluate the anti-arthritic efficacy of aquo-alcoholic extract of Camellia sinensis (L.).

MATERIAL AND METHODS

Dried leaves of Camellia sinensis (L.) or Cs were filtered and extracted in 1:1 aqueous: ethanol by Soxhlet apparatus followed by lyophilization and spray drying to develop amorphous powder. Four different oral doses (50, 100, 200, 400mg/kg/body wt.) of aquo-alcoholic extract were evaluated for anti-edematogenic effect in collagen induced arthritis model. The selected anti-arthritic doses of Cs were evaluated for the oxidative stress markers like Glutathione [5-5'dithio-bis-2-nitrobenzoicacid (DTNB)], Superoxide dismutase [Epinephrine], Catalase [Hydrogen peroxide], Lipid peroxidation [Thiobarbituric acid reactive substance (TBARS)], Nitric oxide [Griess reagents:Nitrobluetetrazolium], Articular elastase [N-methoxysuccinyl-Ala-Ala-Pro- Val p-nitroanilide] in joints followed by haematological evaluation including RBC, WBC, Haemoglobin, platelets and haematocrit. To validate these biochemical changes, the radiological and histopathological (Haematoxylin & Eosin) evaluation was also conducted.

RESULTS

The selected anti-arthritic dose of Cs i.e. 400mg/kg/body wt. (∼60% anti-arthritic efficacy on 35th day) could be attributed towards significant (p<0.05) increase in the levels of enzymatic (Superoxide dismutase and Catalase) and non-enzymatic (Glutathione) antioxidants by 34%, 59% and 50% respectively. Simultaneously, the significant (p<0.05) reduction of lipid peroxides, nitrite radical and elastase activity by 32%, 45% & 32% respectively as compare to control indicated overall decrease in oxidative stress. Haematological evaluation revealed restoration of RBC, WBC and platelets level in treatment group. The confirmatory analysis utilizing radiological and histological assessment showed alleviation of joint deformity, tissue swelling, pannus formation and neutrophils infiltration in treatment group as compared to collagen induced arthritis.

CONCLUSION

The analysis showed that Cs can play an effective role in reduction of oxidative stress by modulating levels of antioxidants, reducing levels of free radicals while restoring normal haematopoietic cascade as observed in collagen induced arthritis model. Thus, the cumulative dose impact of 400mg/kg body wt., over a period of 14days also found extremely effective in terms of safeguarding their structural conformity against such auto-immune disorder.

Therapeutic targeting of IL-6 trans signaling counteracts STAT3 control of experimental inflammatory arthritis

Cytokine control of the synovial infiltrate is a central process in the development of inflammatory arthritis. In this study, we combine genetic approaches and intervention strategies to describe a fundamental requirement for IL-6-mediated STAT3 signaling in orchestrating the inflammatory infiltrate in monoarticular and systemic models of experimental arthritis. STAT3 activation via the common gp130 signal-transducing receptor for all IL-6-related cytokines led to increased retention of neutrophils and T cells within the inflamed synovium, which included STAT3-regulated IL-17A-secreting T cells. Control of leukocyte infiltration was reliant upon IL-6 signaling via its soluble receptor (termed IL-6 trans signaling), as evidenced by selective blockade of this alternative IL-6 signaling pathway using an engineered variant of soluble gp130 (sgp130Fc). This therapeutic intervention led to substantial clinical improvement in mice with emerging or established incidence of systemic arthritis. These data illustrate that IL-6 control of STAT3 is critical for regulating the synovial infiltrate in inflammatory arthritis, and suggest that selective inhibition of IL-6 trans signaling may provide a more refined intervention strategy for blocking IL-6-driven proarthritic activities.

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.

Bacterial components in the synovial tissue of patients with advanced rheumatoid arthritis or osteoarthritis: analysis with gas chromatography-mass spectrometry and pan-bacterial polymerase chain reaction

OBJECTIVE

To study the presence of bacterial components in the synovial tissue (ST) of patients with advanced rheumatoid arthritis (RA).

METHODS

ST was collected during joint surgery from 41 RA patients. Tissue from 39 patients with osteoarthritis (OA), 4 patients with undifferentiated inflammatory arthritis (UA), and 3 cases of accidental deaths served as controls. The pan-bacterial polymerase chain reaction (PCR) with primers for the 23S ribosomal RNA (rRNA) and 16S rRNA genes was used to detect bacterial DNA. In addition, synovial fluid (SF) samples from patients with chlamydial reactive arthritis (ReA) were also examined by the same method. The positive controls, bacterial DNA or ST spiked with different living bacteria, were analyzed alongside clinical samples. Most of the ST samples were also analyzed by gas chromatography-mass spectrometry (GC-MS) for determining the presence of bacteria-derived muramic acid. Strict precautions were followed in the clinics and the laboratory to prevent contamination.

RESULTS

In GC-MS analysis, muramic acid was observed in the ST from 4 of 35 RA patients and from 2 of 14 OA patients, but not in ST from 2 patients with UA and 3 cadavers. Bacterial DNA was not detected by either one of the PCR primers used in ST from 42 patients with RA and 39 patients with OA. However, 5 of 15 SF samples from ReA patients were PCR positive. The sensitivity of GC-MS to detect muramic acid was 2 pg/injected amount (227 pg muramic acid/mg ST), and that of the pan-bacterial PCR was 2-20 bacteria colony forming units/reaction.

CONCLUSION

These results indicate that a bacterial component, muramic acid, is detectable by GC-MS in ST from a few patients with advanced RA or OA. However, no bacterial DNA was detectable by PCR.

Failure To detect muramic acid in normal rat tissues but detection in cerebrospinal fluids from patients with Pneumococcal meningitis

Muramic acid serves as a marker for the presence of bacterial cell wall debris in mammalian tissues. There have been a number of controversial and sometimes conflicting results on assessing the levels of muramic acid in health and disease. The present report is the first to use the state-of-the art technique, gas chromatography-tandem mass spectrometry, to identify and quantify the levels of muramic acid in tissues. Muramic acid was not found in normal rat brain or spleen. However, when tissues were spiked with muramic acid, it was readily identified. The detection limit was <1 ng of muramic acid/100 mg (wet weight) of tissue. The levels of muramic acid reported in diseased human spleen and spleen of arthritic rats, previously injected with bacterial cell walls, were 100- to 1,000-fold higher. In the present study, muramic acid was also readily detected in the cerebrospinal fluid of patients with pneumococcal meningitis (6.8 to 3,900 ng of muramic acid/ml of cerebrospinal fluid). In summary, there can be an enormous difference in the levels of muramic acid found in different mammalian tissues and body fluids in health and disease. This report could have great impact in future studies assessing the role of bacterial cell wall remnants in the pathogenesis of certain human inflammatory diseases.

Characteristics of polyarthritis in rabbits by hyperimmunization with attenuated Enterococcus faecalis

To produce polyarthritis and rheumatoid factor like substance (RFLS), rabbits were hyperimmunized intravenously with 0.02% thimelosal (TMS)-treated Enterococcus faecalis (E. faecalis) as a persistent bacterial flora. Swelling of knee joints occurred at a rate of 41% (27/66), and of shoulder joints at a rate of 25% (17/66) while that of elbow joints occurred at a rate of 4.5% (3/66). On culturing of knee joint fluids, no colonies appeared while 2/4 fluid specimens from the shoulder joints gave positive colonies for 78 days after the first immunization; thereafter, no colonies appeared. On histological examination, in early stages, acute inflammatory reactions with degenerative changes of synovial tissue was observed. In later stages, chronic inflammatory changes, proliferation of synovial cells with pannus formation, destruction of articular cartilage and subchondral bone were observed. RFLS titer showed bi-phasic peaks at 11 days and 41 days after the first immunization. A high incidence of polyarthritis, particularly knee joints, occurred. Thus, hyperimmunization with attenuated E. faecalis as a normal intestinal flora may provide an animal model of chronic polyarthritis.

Sterile neutrophilic folliculitis with perifollicular vasculopathy: a distinctive cutaneous reaction pattern reflecting systemic disease

The authors prospectively encountered skin biopsies from 20 patients which demonstrated a neutrophilic or suppurative and granulomatous folliculitis accompanied by a folliculocentric neutrophilic vascular reaction of Sweet's-like or leukocytoclastic vasculitis subtypes. While in each case the histomorphology raised diagnostic consideration of bacterial folliculitis, patients frequently expressed systemic complaints such as arthritis, fever, and malaise, and special stains for micro-organisms were negative. Among the clinical presentations were folliculitis, vasculitis, acneiform eruptions, vesiculopustular lesions, and erythema nodosum-like lesions, with the legs, arms, and upper back being the most commonly involved sites. Nineteen patients were found to have specific underlying systemic diseases, namely, inflammatory bowel disease, Reiter's disease, Behçet's disease, hepatitis B, connective tissue disease including mixed connective tissue disease and rheumatoid arthritis, scrofuloderma, and hematologic dyscrasias. The other patient had antecedent bacterial sinusitis in the setting of atopy. The folliculocentric nature of these lesions may reflect preferential processing of antigens through the hair follicle and/or homology between bacterial and follicular heat shock proteins in the susceptible host, namely, one who responds excessively to exogenous antigenic triggers. Folliculitis with folliculocentric vasculopathy may be a clue to underlying systemic disease and/or an extracutaneous infection. Certain light microscopic features in concert with the clinical presentation may distinguish such cases from conventional infectious folliculitis.

Role of enteric bacteria in the pathogenesis of rheumatoid arthritis: evidence for antibodies to enterobacterial common antigens in rheumatoid sera and synovial fluids

OBJECTIVE

To study antibodies to Escherichia coli O:14, which expresses large amounts of enterobacterial common antigen (ECA), and their corresponding antigen molecules in serum and synovial fluid samples from patients with rheumatoid arthritis (RA).

METHODS

Enzyme linked immunosorbent assay (ELISA) was used to measure antibodies to heat killed E coli O:14 in serum and synovial fluid samples from patients with RA and control subjects including healthy donors and patients with osteoarthritis. ELISA was also used to perform absorption analyses of antibodies to E coli O:14 with several enteric bacteria and their lipopolysaccharide (LPS). In addition, antigenic molecules reacting with E coli O:14 antibodies from patients with RA were examined using immunoblot analysis and N-terminal amino acid analysis.

RESULTS

Compared with control subjects, patients with RA showed significantly increased titres of antibodies against heat killed E coli O:14 in 33 of 83 serum samples (39.8%) and 38 of 58 joint fluid samples (65.5%). Absorption analyses with enteric bacteria and their LPS resulted in the reduction of antibody titres to heat killed E coli O:14 in serum and synovial fluid samples from the RA patients. In addition, immunoblot analysis of the samples from RA patients revealed not only a ladder-like banding pattern equivalent to ECA associated with LPS, but also two clear bands of bacterial outer membrane proteins of 35 kDa (Omp A) and 38 kDa (Omp C), having amino acid sequence homology with those of other Enterobacteriaceae.

CONCLUSION

These results suggest that some patients with RA are sensitised to antigens common to Enterobacteriaceae, and this may prove relevant to the future development of immunotherapy for RA. Furthermore, this sensitisation to antigens found commonly in Enterobacteriaceae may have a key role in the pathogenesis of human RA similar to that described previously in our animal model.

Abnormal colonic microbial function in patients with rheumatoid arthritis

The aim of this study was to examine the microflora-associated characteristics (MACs) of faecal samples of patients with rheumatoid arthritis (RA) and to evaluate the actions of sulphasalazine (SASP) on these MACs. The conversion of cholesterol to coprostanol, the production of urobilinogen, the degradation of faecal tryptic activity (FTA) and of beta-aspartylglycine were measured in faecal samples from 19 patients treated with SASP and 21 patients not treated with this medication. A control group of 21 healthy subjects was sex- and age-matched with the untreated patients. The conversion of cholesterol to coprostanol showed a bimodal distribution. The frequency of high converters in patients without SASP treatment was higher than in healthy subjects (p < 0.05). Treatment with SASP markedly increased the FTA and reduced the urobilinogen values, as compared to the untreated patients (p < 0.05). Beta-aspartylglycine was not found in any faecal samples. The results indicate that patients with RA have an abnormal formation of coprostanol, which is ascribed to alterations in the function of the Eubacteria species. In patients with RA, SASP treatment induces disturbances in the metabolism of the microflora.

Small intestinal bacterial overgrowth in patients with rheumatoid arthritis

OBJECTIVES

To examine the microflora of the upper small intestine in patients with seropositive rheumatoid arthritis (RA) using a combination of microbial cultivation and tests for microbial metabolic activity.

METHODS

Twenty five patients with seropositive RA, 12 achlorhydric control subjects, and 11 control subjects with normal gastric acid secretion were investigated. Disease activity was evaluated in the patients with RA by three different indices. Eight (32%) of the patients with RA had hypochlorhydria or achlorhydria. The acid secretory capacity was determined with pentagastrin stimulation. A modified Crosby capsule was used to obtain biopsy specimens and samples of intestinal fluid from the proximal jejunum; aerobic and anaerobic microbial cultivation of mucosal specimens/intestinal fluid was carried out, and gas production and microflora associated characteristics in jejunal fluid were determined. Additionally, a bile acid deconjugation breath test was performed.

RESULTS

Subjects with at least one of the following findings were considered to have bacterial overgrowth: positive bile acid deconjugation test; growth of Enterobacteriaceae; positive gas production; or low tryptic activity. By these criteria half of the patients with RA with hypochlorhydria or achlorhydria and half of the achlorhydric controls had bacterial overgrowth. Thirty five per cent of the patients with RA with normal gastric acid secretion had bacterial overgrowth compared with none of the normal controls. Disease activity indices and rheumatoid factor titres were significantly higher in patients with RA with bacterial overgrowth than in those without.

CONCLUSIONS

A high frequency of small intestinal bacterial overgrowth was found in patients with RA; it was associated with a high disease activity and observed in patients with hypochlorhydria or achlorhydria and in those with normal acid secretion.

Food intolerance in rheumatoid arthritis. I. A double blind, controlled trial of the clinical effects of elimination of milk allergens and azo dyes

The hypothetically negative influence of food on the clinical activity of seropositive rheumatoid arthritis was studied using two types of artificial elementary food. One diet was allergen free, the other allergen restricted, containing only lactoproteins and yellow dyes. Ninety four patients entered the study, which lasted 12 weeks. During the second four week period they were randomly assigned to one of the two artificial foods. Comparison between baseline and subsequent periods showed only subjective improvements. No differences were seen between the clinical effects of the two tested diets. Nine patients (three in the allergen restricted group, six in the allergen free group) showed favourable responses, followed by marked disease exacerbation during rechallenge. Dietary manipulation also brought about changes in objective disease activity parameters in these patients. The existence of a subgroup of patients in whom food intolerance influences the activity of rheumatoid factor seropositive rheumatoid arthritis deserves serious consideration.

Arthritis by autoreactive T cell lines obtained from rats after injection of intestinal bacterial cell wall fragments

T cell lines (B13, B19) were isolated from the lymph nodes of Lewis rats 12 days after an arthritogenic injection of cell wall fragments of Eubacterium aerofaciens (ECW), a major resident of the human intestinal flora. These cell wall fragments consist of peptidoglycan polysaccharide complexes (PPC). The cell lines that bear the helper phenotype were arthritogenic in knee or ankle joints upon intravenous injection into irradiated Lewis recipients. B13 was, however, not arthritogenic in irradiated F344 recipients that are largely RT1 identical. The arthritis induced in the knee joints of the irradiated Lewis rats was clearly shown by a 99mtechnetium-pertechnetate scanning technique and was confirmed histologically. In vitro the cell lines showed a proliferative response after stimulation with syngeneic spleen cells alone. The proliferation was significantly higher when bacterial PPC, isolated in soluble form from normal feces or ileostomy fluid were added. Recognition by B13 appeared to be MHC class II restricted. These results show that autoreactive T cell lines can be isolated from rats after injection of bacterial cell wall antigens and that these cell lines can be arthritogenic. This suggests a role for autoreactive T cells in the induction of bacterial cell wall arthritis and might give a clue for the arthritogenic properties of the normal human intestinal flora.

Are intestinal bacteria involved in the etiology of rheumatoid arthritis? Review article

Observations in bowel-related joint diseases give support to this hypothesis. In Crohn's disease and ulcerative colitis, the bowel wall inflammation is complicated in about 20% of the patients by joint inflammation. Bowel infection by Salmonella, Shigella and Yersinia can provoke joint inflammation and supports an etiological link between bowel bacteria and arthritis. The arthropathic properties of the most abundant group of intestinal bacteria, i.e. the obligate anaerobic bacteria, were studied in an animal model. Cell wall fragments (CWF), with peptidoglycan as the major component, from some Eubacterium and Bifidobacterium species induced a severe chronic polyarthritis in Lewis rats after a single intraperitoneal injection. Eubacterium was found in numbers of 10(8)-10(9) per gram in stools of healthy subjects and rheumatoid arthritis (RA) patients. CWF of isolated strains of E. aerofaciens were arthropathic. Soluble peptidoglycan polysaccharide complexes (PG-PS) originating from the obligate anaerobic flora were purified from human intestinal contents. PG-PS from ileostomy fluid that proved to be less processed by intestinal enzymes induced chronic arthritis in rats after a single administration in oil in the base of the tail. It was concluded that the human intestinal bowel contains soluble bacterial cell wall products that are arthropathic in an animal model. Peptidoglycan (PG) or its subunits was reported to be present in mammalian tissues. Immunohistochemical studies from our group showed the presence of intestinal PG-PS in sections of normal rat spleen. Bacterial cell wall or PG-induced joint inflammation in rats is proven to be absolutely dependent on functional T cells. T-cell lines were isolated from the lymph nodes of rats with an E. aerofaciens CWF arthritis. A helper T-cell line B13 was in vivo arthritogenic in knee or ankle joints upon intravenous injection in rats and proliferated in vitro on syngeneic spleen cells alone, but was additionally stimulated by intestinal PG-PS and E. aerofaciens CWF. It was postulated that the arthritogenic T cells that seem to be autoreactive are, in fact, recognizing bacterial PG-PS on antigen-presenting cells (APC). It is generally accepted that RA is a T-cell-dependent process and that therefore the reaction is directed at small peptides bound by the major histocompatibility complex of APC. The only peptides present in arthritis inducing intestinal PG-PS and in CWF are PG peptides interlinking the sugar chains. We feel that the immunoreaction against PG peptides plays a pivotal role in experimental and human arthritis of an unknown etiology.

Induction of arthritis in rats by soluble peptidoglycan-polysaccharide complexes produced by human intestinal flora

Peptidoglycan-polysaccharide complexes were isolated from feces of a healthy subject and from ileostomy fluid from 5 patients. Peptidoglycan-polysaccharide complexes were tested for arthritogenicity in a rat model, by subcutaneous injection in Freund's incomplete adjuvant. Complexes from the healthy subject did not induce arthritis, but those from ileostomy fluid of 1 of the patients induced severe, chronic joint inflammation. We concluded that peptidoglycan-polysaccharide complexes from intestinal flora are potentially arthritogenic in rats. This arthritogenicity may be influenced by the content of muramic acid and rhamnose in these complexes.

Histology of joint inflammation induced in rats by cell wall fragments of the anaerobic intestinal bacterium Eubacterium aerofaciens

To study the arthropathic properties of human intestinal bacteria, cell wall fragments (CWF) of the anaerobic bowel bacterium Eubacterium aerofaciens were injected intraperitoneally (i.p.) in arthritis-susceptible Lewis rats. Rat paw joints were subsequently studied for histopathological changes. A persisting synovitis accompanied by marginal erosions of cartilage and bone and a marked periosteal apposition of new bone tissue were the main features of the polyarthritis induced. These results are discussed in relation to streptococcal cell wall induced arthritis and compared with histopathological findings in rheumatoid arthritis (RA) in man.

Rheumatoid arthritis, food, and allergy

One of the most promising lines of research on the etiology and pathogenesis of rheumatoid arthritis (RA) is its association with the genetically determined MHC class II antigens. The function of these macromolecules, presentation of antigens to the T-helper cells, supports the possibility that external antigens influence RA. We review available literature concerning the relationship between RA and food. Circumstantial evidence suggests that some foods or food components might influence subgroups of RA patients, although many of the publications on this subset do not meet acceptable standards of modern medical research.

The effect of olive oil and fish consumption on rheumatoid arthritis--a case control study

In an interview based, case control study of Rheumatoid Arthritis (RA) 168 cases and 137 controls were included. Patients and controls were interviewed with regard to a variety of socioeconomic, medical and dietary factors. During univariate analysis it was found that RA cases consumed significantly less olive oil and fish and adhered more rarely to the dietary restrictions traditional in Orthodox lent than controls. Applying multiple logistic analysis though (by which several variables were controlled for), only the association with olive oil consumption and lent adherence remained significant. More specifically; an increase in olive oil consumption by two times per week, resulted in a Relative Risk (RR) for development of RA of 0.49, whereas adherence to lent during the 27 weeks per year prescribed by the Orthodox Church, resulted in a RR of 0.33. We conclude that olive oil consumption and adherence to Orthodox lent may have a protective effect on the development and/or the severity of RA. This is a hypothesis generated by the present study that needs verification.

Mycoplasma fermentans-derived high-molecular-weight material induces interleukin-6 release in cultures of murine macrophages and human monocytes

A Mycoplasma fermentans-derived high-molecular-weight material (MDHM) is described which causes differentiation of concanavalin A-stimulated CBA/J or C57BL/6 mouse thymocytes to cytolytic effector T cells (CTLs). The effect of MDHM was inhibited by addition of monoclonal anti-interleukin-6 (IL-6) antibody. It could also be abolished after removal of adherent cells. However, adherent cell-depleted thymocytes could still form CTLs after addition of IL-6. The action of MDHM could thus be explained by the capacity of MDHM to stimulate IL-6 release from adherent cells. MDHM was active on macrophages from CBA/J and C3H/HeJ endotoxin nonresponder mice and was also capable of stimulating IL-6 release from human monocytes. On gel chromatography, MDHM had an apparent molecular size of 1.5 x 10(6) daltons. Treatment with RNase and DNase had no effect on either size or biological activity. Proteinase K did not abolish activity but reduced the apparent molecular size of MDHM. MDHM production by M. fermentans required either coculture with eucaryotic cell lines in RPMI 1640 medium with fetal calf serum or addition of eucaryotic cell sonic extracts to this medium. The biological activity of MDHM is not identical to that of a mitogen for murine spleen cells derived from M. arthritidis; MDHM caused only slight proliferation in this system compared with the mitogen from M. arthritidis, and the latter did not elicit IL-6 release from macrophages. The results are discussed in relation to mycoplasmas as putative etiological agents for rheumatoid arthritis, since high IL-6 titers were reported for synovial fluid from patients with this disease.

Chronic arthritis induced in rats by cell wall fragments of Eubacterium species from the human intestinal flora

To investigate arthritis-inducing properties of Eubacterium species, which are major residents of the human intestinal flora, cell wall fragments (CWF) of several Eubacterium strains were prepared and tested in an animal model. After a single intraperitoneal injection in the rat, CWF of E. aerofaciens, E. contortum, and E. lentum induced a chronic polyarthritis. E. limosum and E. tortuosum CWF induced an acute self-limiting joint inflammation, whereas E. rectale CWF failed to do so. The rhamnose contents of the isolated CWF were not related to their arthritis-inducing properties. Paradoxically, the sensitivity of CWF to lysozyme digestion, which is regarded as a parameter for the clearance of CWF in tissues, appeared to be positively correlated with the ability of Eubacterium CWF to induce chronic joint inflammation. Our findings show the diversity in arthritis-inducing properties among different species of the anaerobic genus Eubacterium and underline the importance of the anaerobic intestinal flora in the induction of joint inflammation.

Mass spectrometric quantitation of muramic acid, a bacterial cell wall component, in septic synovial fluids

This is the first report describing the use of gas chromatography-mass spectrometry for detection of muramic acid in infected synovial fluid (SF). Muramic acid is a ubiquitous component of bacterial cell walls, and it has been proposed that it could serve as a chemical marker for the presence of live bacteria or bacterial debris in rheumatoid joints. Our goal was to determine whether muramic acid was present at detectable levels in septic SF, since this would serve as a positive control for studies of reactive and rheumatoid arthritis. Muramic acid was found to be present at levels of less than 250-1,700 ng/ml in 12 septic SF samples (10 of which were culture positive for Staphylococcus aureus and 1 each for Escherichia coli and Streptococcus pneumoniae). Among these samples, those containing low bacterial colony counts did not contain detectable muramic acid. Muramic acid was also not detected in any SF samples from 20 control patients. We conclude that muramic acid can be used as a marker for the presence of bacterial peptidoglycan in SF. With further lowering of gas chromatography-mass spectrometry detection limits, determination of the quantities of bacterial debris present in joints of patients with rheumatoid or reactive arthritis will be attainable.

Intestinal mucosal permeability and rheumatological diseases

Rheumatological disorders frequently have gastrointestinal manifestations and, conversely, intestinal disorders frequently have rheumatological manifestations. The possibility of altered intestinal permeability in arthritic patients may provide the bridge needed to link the two organ systems. The normal intestine absorbs nutrients and excludes the remaining material. If the intestine were less discriminating or 'leaky' then material normally excluded would be able to cross the intestinal mucosa into the lamina propria. An inflammatory response to these antigens, be they dietary, bacterial, or viral in origin, could produce either local or systemic disease. This would depend upon the type of immunological response and the cross-reactivity between the host's antigens and the absorbed antigens. This theory could account for the postulated relationship between intestinal abnormalities and the pathogenesis of some forms of arthritis.

Effects of prostaglandin E2 on disease activity, gastric secretion and intestinal permeability, and morphology in patients with rheumatoid arthritis

The effects of oral natural prostaglandin E2 (PGE2) on symptoms, disease activity, and gastrointestinal functions in rheumatoid arthritis (RA) were studied in an open pilot trial. Twelve patients, six taking and six not taking non-steroidal anti-inflammatory drugs (NSAIDs), received 1 mg natural PGE2 three times a day for six weeks. The treatment was tolerated well and the only side effect noted was slightly looser stools in three patients. Half of the patients reported subjective improvement and none had aggravation of symptoms. The Ritchie articular index and several biochemical inflammation markers decreased and were significantly reduced at the end of the treatment period. The thickness of the small intestinal mucosa increased during the PGE2 treatment. The intestinal permeability pattern, measured by urinary excretion of polyethylene glycols (PEG 400), differed between the patients taking and not taking NSAIDs. The initially high urinary PEG 400 excretion values in the patients taking NSAIDs decreased and the initially low excretion values in patients not taking NSAIDs increased during the PGE2 treatment. The jejunal contents became sterile in 5/6 patients not taking NSAIDs and remained sterile in 1/6 patients taking NSAIDs at the end of the treatment. The treatment period was associated with a reduction of lactobacilli in patients not treated with NSAIDs. Thus the treatment appeared to decrease disease activity and to improve small intestinal functions in patients with RA, findings that need confirmation in a controlled trial.

Arthritis-associated changes in flow cytometric characteristics of cultured synovial fibroblasts

Synovial fibroblasts cultured from patients with rheumatoid or reactive arthritis and from controls were studied by flow cytometry, spectroscopy, and electron microscopy. Analysis of 29 cell lines revealed consistent differences between arthritic and normal fibroblasts. Cells cultured from inflamed synovial tissue exhibited higher autofluorescence than did control fibroblasts, and displayed exceptional light scatter properties in flow cytometry, indicating changes in cytoplasmic structures. Electron microscopic examination of the fibroblasts from arthritic synovial tissue revealed large numbers of round, swollen, laminated, mitochondrion-like bodies, which were not observed in the control fibroblasts. The changes observed by flow cytometry (light scatter and autofluorescence) coincided with the presence of the mitochondrion-like organelles. The strong autofluorescence observed in the arthritic fibroblasts resembled the fluorescence spectrum of mitochondrial flavoproteins. These data suggest that persistent metabolic and structural changes have occurred in the mitochondria of synovial fibroblasts and inflammatory synovial tissue. The usefulness of flow cytometry in identifying such cells is described.

Analysis of serum and synovial fluid IgA in Reiter's syndrome and reactive arthritis

The presumed antecedent infection which precedes Reiter's syndrome and reactive arthritis is frequently across a mucosal surface, and IgA immune responses may play a role in this process. Twelve of 29 patients with these conditions demonstrated elevation in serum IgA levels, and serum IgA levels in the postdysentery group (mean 3.21 g/liter +/- 1.27) were higher (P less than 0.01) than those in the posturethritis group (mean 2.40 g/liter +/- 0.80). In 10 of the 12 patients, IgA was the only immunoglobulin increased. There was no evidence of activation of complement in serum or synovial fluid. Using a complement-dependent assay, we were unable to demonstrate circulating IgA immune complexes. Sucrose density gradient ultracentrifugation analysis was used to assess IgA immune complexes in a non-complement-dependent manner. IgA of 11s was in fact demonstrated by this technique but appeared to be polymeric IgA on the basis of specific binding of secretory component and resistance to acid dissociation. IgA rheumatoid factor was not present. Synovial fluid revealed levels of polymeric IgA higher (mean 56.7% +/- 12.9) than did serum (23.7% +/- 13.9, P less than 0.001) despite higher levels of total IgA in serum than in synovial fluid (synovial fluid:serum ratio of IgA, mean 0.53 +/- 0.11). Although elevation in serum IgA in postdysenteric arthropathies suggests mucosal acquisition of antigen, the study does not implicate IgA circulating immune complexes in the pathogenesis of these diseases.

Infection and arthritis

The categorization in four classes of association between infection and arthritis (namely infective, post-infective, reactive and idiopathic) seems nowadays to be inadequate to cover the extensive field of interactions between infectious agents and host response resulting in arthritis. This paper is a synthetic review of the subject with particular reference to pathogenetic mechanisms in children. An effort has been accomplished, on the basis of the most recent literature, to define the respective roles of the microbial aggression and the host response in a number of conditions: septic arthritis, viral arthritides, Lyme arthritis, rheumatic fever, Reiter's syndrome, ankylosing spondylitis and rheumatoid arthritis.

Bacterial arthritis. A staphylococcal proteoglycan-releasing factor

We report the effect of staphylococci on induction of proteoglycan release from cartilage in organ culture and document the presence of a staphylococcal proteoglycan-releasing factor in the bacterial growth medium. Staphylococci cocultured with cartilage increased release of proteoglycan 3-4-fold within 48 hours. Viable cartilage was essential for maximum loss of proteoglycan. Killed bacteria had no effect on proteoglycan release. Four Staphylococcus aureus strains yielded growth media preparations active in proteoglycan release. Analysis of the proteoglycan subunits released from cartilage showed only limited degradation, and glycosaminoglycan chain length was not significantly altered.

Induction of chronic polyarthritis in rabbits by hyperimmunization with Escherichia coli. I. Pathologic and serologic features in two breeds of rabbits

Hyperimmunization of 147 rabbits (outbred Japanese white rabbits and New Zealand white [NZW] rabbits bred in a closed colony) with heat-killed Escherichia coli 0:14 in Freund's incomplete adjuvant resulted in the animals developing a chronic polyarthritis resembling rheumatoid arthritis (RA). While both Japanese white and NZW rabbits showed a high incidence of the induced arthritis, a higher proportion of NZW rabbits developed the disease, suggesting that genetic influence is important in the development of RA-like illness. This experimental model may be useful for the study of RA.

Etiology of rheumatoid arthritis

Definite genetic associations with immunological cooperative HLA-D(R) antigens have been demonstrated for rheumatoid arthritis (RA). Microbial etiology has not been proven, but some hope for the supporters of this view is still given by small viruses, plasmids of enteric bacteria or perhaps oncogen-like DNA-sequences. Yet, electrophoretical analysis of membrane proteins or surface glycoproteins of RA synovial cells does not show any differences compared to reference cells. Autoimmunity to several tissue elements has been demonstrated, but most of it is of secondary nature. Antigenicities of type II and III collagens are probably only contributory factors for HLA-DR4 positive individuals. Proteoglycans or minor cartilage collagens have not been extensively studied, so far. Endocrine, dietary or psychological influences might be triggering events for otherwise 'preloaded' individuals.

Pain and inflammation

The traditional "aspirin first" approach to the treatment of osteoarthritis and rheumatoid arthritis is undergoing serious reappraisal. Aspirin and acetaminophen are equipotent in their analgesic efficacy; however, aspirin is associated with a higher incidence of side effects. Acetaminophen should therefore be used as first-line therapy for the treatment of osteoarthritis since reduction of pain is the primary therapeutic objective. Analgesic doses of aspirin (up to 3,900 mg per day) do not produce an anti-inflammatory effect and thus are not beneficial in the treatment of rheumatoid arthritis. Only high doses of aspirin (4 to 6 g per day) used for a sustained period produce an anti-inflammatory effect. Since many patients with rheumatoid arthritis cannot tolerate long-term use of anti-inflammatory doses of aspirin, it may be preferable to initiate therapy with one of the newer nonsteroidal anti-inflammatory drugs.

Detection of soluble peptidoglycan in urine after penicillin administration

A unique enzyme-linked immunosorbent assay was developed to detect soluble peptidoglycans in biological fluids. It makes use of the similar affinities of vancomycin and purified rabbit antibodies to peptidoglycan precursor sequences found in soluble peptidoglycans. This assay has been used to detect as little as 500 pg of soluble peptidoglycan per ml of serum and 5 pg/ml of urine. Studies of normal individuals and Staphylococcus aureus-infected patients revealed only a few sera with detectable levels of soluble peptidoglycans. Studies of normal volunteers who were given a single oral dose of 250 mg of penicillin VK showed that about half had detectable levels of soluble peptidoglycans in their urine up to 6 h after ingestion. This suggests that soluble peptidoglycans can be released by indigenous bacteria in detectable amounts. In one volunteer, a detectable level of soluble peptidoglycan in the urine at 6 h decreased to an undetectable level at 12 h. Such an ephemeral appearance of soluble peptidoglycan in the urine could account for the small number of human sera that had detectable levels of soluble peptidoglycan.

Preferential immune response to virion surface glycoproteins by caprine arthritis-encephalitis virus-infected goats

Six months after inoculation with caprine arthritis-encephalitis virus, the serum and synovial fluid of virus-infected goats had antibodies to [35S]methionine-labeled viral proteins with apparent molecular weights of 125,000, 90,000, 28,000, and 15,000. The 125,000-, 90,000-, and 15,000-molecular-weight methionine-labeled proteins were identified as virion surface glycoproteins by lactoperoxidase iodination and galactose oxidase-boro[3H]hydride reduction labeling techniques. Radioimmunoassay antibody titers to purified p28, the most abundant viral structural protein, averaged 1:182 in synovial fluid and 1:67 in serum 6 months after inoculation. High dilutions of serum and synovial fluid reacted with gp90 and gp125 electroblotted onto nitrocellulose paper from polyacrylamide gels. Anti-gp90 activity was detected at dilutions with an immunoglobulin G content of 0.02 to 11 micrograms, whereas antibody to p28, when detectable on Western blots, was present in samples with an immunoglobulin G content of 0.1 to 2 mg, representing 100- to 1,000-fold-greater titers of antibody to the surface glycoprotein. Synovial fluids often contained more anti-gp90 antibody than did sera. Immunoprecipitation of lactoperoxidase-iodinated virus confirmed the presence of high antibody titers to the two virion surface glycoproteins. Because antiviral gp90 and gp125 antibody is abundant in the synovial fluid of infected goats, it probably contributes to the high immunoglobulin G1 concentrations seen at this site 6 months after caprine arthritis-encephalitis virus infection.

Plasma membrane glycoproteins of cultured rheumatoid synovial fibroblasts

Fibroblast cultures were started from synovial tissue samples of 12 rheumatoid arthritic, 9 non-rheumatoid synovitic and 6 control patients. External galactose units of plasma membrane glycoproteins of confluent cells were labelled using the galactose oxidase-tritiated borohydride method. These surface-labelled cells were analyzed for possible differences in their glycoproteins by electrophoresis in SDS-containing polyacrylamide gradient gels. Total cell lysates were separated into 50-60 polypeptide bands. Fluorography of the gels revealed about 20 labelled plasma membrane glycoproteins. Some strain-specific differences were detected between the samples in all the groups, but no correlation with rheumatoid arthritis could be demonstrated.

Dermatologic conditions reported in patients with rheumatoid arthritis

Dermatologists, while becoming increasingly involved in the diagnosis and management of patients with connective tissue diseases, have left rheumatoid arthritis relatively unexplored. An increased awareness of possible pathomechanisms of rheumatoid arthritis may allow for generalizations that lead to increased understanding of other connective tissue disorders. The types of cutaneous disorders that occur in association with rheumatoid arthritis include: vasoreactive dermatoses (e.g., various forms of vasculitis), which may occur secondary to the circulating immune complexes present in rheumatoid arthritis; autoimmune bullous disorders, which may occur in the setting of a suppressor T cell defect in rheumatoid arthritis; and various miscellaneous cutaneous associations. Hopefully, this review will lead to an increased understanding of both rheumatoid arthritis and the wide array of cutaneous associations of rheumatoid arthritis.

Immunocytological studies of Epstein-Barr viral antigen and antibody in rheumatoid synovial fluids

Evidence for intra-articular immunity to Epstein-Barr virus (EBV) was sought in synovial fluids (SF) and SF phagocytes derived from patients with and without rheumatoid arthritis (RA). Antibody titres to EBV were not significantly different in SF of 32 RA and 25 non-RA patients. Whereas the majority of RA patients (69%) showed Ig-containing complexes (IC) in SF phagocytes, fluorescent antibody staining of these by anti-EBV serum was negative except with 6 RA patients. Extended analysis of the SF phagocytes of the latter, however, showed no EBV specificity in their IC, suggesting that these represented non-specific "pseudo-IC'. These studies do not support a role for EBV-containing IC in the propagation of rheumatoid synovitis and demonstrate that not all immunofluorescent inclusions in RA phagocytes (ragocytes) represent immune complexes.