Polysaccharides and glycosides from Aralia echinocaulis protect rats from arthritis by modulating the gut microbiota composition.

ETHNOPHARMACOLOGICAL RELEVANCE: Aralia echinocaulis has been used in traditional medicines in China and exhibits good effects on rheumatoid arthritis (RA). AIM OF THE STUDY: Aralia echinocaulis is rich in polysaccharides and glycosides. This study aims to explore the effect of total polysaccharide and glycoside (TPG) from A. echinocaulis on an RA rat model and the role of alterations in gut microbes mediated by TPG. MATERIALS AND METHODS: In this study, a collagen-induced arthritis (CIA) rat model was constructed and used to evaluate the effects of TPG in vivo. 16S rRNA sequencing was used to detect the changes in the gut microbiota. A cooccurrence analysis was conducted by calculating Spearman's rank correlations. Microbial functions were predicted using PICRUSt with the KEGG and COG databases. RESULTS: The results showed that TPG from A. echinocaulis could inhibit arthritis, reduce serum IL-1ß and TNF-α levels, and improve synovial pathology in the RA rat model but failed to produce the same results in a pseudoaseptic RA rat model. 16S rRNA sequencing verified that TPG could modulate the gut microbiota community structure of RA rats. The cooccurrence analysis found 19 out of the 50 most abundant genera in a cooccurrence network, of which 16 showed a positive correlation and 3 showed a negative correlation. KEGG pathway and COG function analyses found that TPG-induced alterations in the gut microbiota might be correlated with the circulatory system, excretory system, metabolic diseases, signaling molecules and interactions, coenzyme transport and metabolism, and nucleotide transport and metabolism. CONCLUSIONS: TPG from A. echinocaulis had significant effects on the RA rat model, which are related to the modulation of the gut microbiota. These results are useful to better understanding the mechanisms of TPG in RA.

Exopolysaccharide from Lactobacillus rhamnosus KL37 Inhibits T Cell-dependent Immune Response in Mice.

Exopolysaccharides (EPSs), major components of the bacterial biofilm, display strong strain-specific immunomodulatory properties. Previously, we have shown that crude EPS derived from Lactobacillus rhamnosus KL37 depresses the production of arthritogenic anti-collagen IgG and ameliorates collagen-induced arthritis (CIA) in DBA/1 mice, when lipopolysaccharide (LPS) was used as adjuvant. In this study, we used highly purified EPS from L. rhamnosus KL37 (EPS-37) to verify its anti-inflammatory properties and the ability to suppress T cell-dependent humoral response. We have employed the model of active CIA, in which mice immunized with type II collagen (CII) along with LPS were treated with pure EPS-37. Intravenous administration of purified EPS-37 markedly ameliorated arthritis and reduced CII-specific antibody production. EPS-37 injected subcutaneously reduced the clinical symptoms of CIA but without the reduction of arthritogenic antibodies. In addition, the effect of EPS-37 on T-cell functions was tested ex vivo and in vitro. EPS-37 inhibited the in vitro proliferation of T cells activated both in vivo (CII immunization) and in vitro (antigen/mitogen), and markedly reduced the production of interferon (IFN)-γ. These results together with other reports suggest that anti-inflammatory potential of EPS-37 depends on its ability to inhibit either one or the other or both possible inflammatory signaling pathways. Namely, Th1 → IFN-γ → M1 inflammatory macrophages → arthritis and/or Th1 → IFN-γ → B cells → arthritogenic antibodies → arthritis. We suggest that L. rhamnosus KL37 EPS might be utilized to control T cell-dependent immune responses in various inflammatory diseases. However, the most effective route of EPS-37 administration needs to be tailored for a given disorder.

Inflammatory arthritis disrupts gut resolution mechanisms, promoting barrier breakdown by Porphyromonas gingivalis.

Rheumatoid arthritis is linked with altered host immune responses and severe joint destruction. Recent evidence suggests that loss of gut homeostasis and barrier breach by pathobionts, including Porphyromonas gingivalis, may influence disease severity. The mechanism(s) leading to altered gut homeostasis and barrier breakdown in inflammatory arthritis are poorly understood. In the present study, we found a significant reduction in intestinal concentrations of several proresolving mediators during inflammatory arthritis, including downregulation of the gut-protective mediator resolvin D5n-3 DPA (RvD5n-3 DPA). This was linked with increased metabolism of RvD5n-3 DPA to its inactive 17-oxo metabolite. We also found downregulation of IL-10 expression in the gut of arthritic mice that was coupled with a reduction in IL-10 and IL-10 receptor (IL-10R) in lamina propria macrophages. These changes were linked with a decrease in the number of mucus-producing goblet cells and tight junction molecule expression in the intestinal epithelium of arthritic mice when compared with naive mice. P. gingivalis inoculation further downregulated intestinal RvD5n-3 DPA and Il-10 levels and the expression of gut tight junction proteins. RvD5n-3 DPA, but not its metabolite 17-oxo-RvD5n-3 DPA, increased the expression of both IL-10 and IL-10R in macrophages via the upregulation of the aryl hydrocarbon receptor agonist l-kynurenine. Administration of RvD5n-3 DPA to arthritic P. gingivalis-inoculated mice increased intestinal Il-10 expression, restored gut barrier function, and reduced joint inflammation. Together, these findings uncover mechanisms in the pathogenesis of rheumatoid arthritis, where disruption of the gut RvD5n-3 DPA-IL-10 axis weakens the gut barrier, which becomes permissive to the pathogenic actions of the pathobiont P. gingivalis.

Design and Synthesis of Novel Amino-triazine Analogues as Selective Bruton's Tyrosine Kinase Inhibitors for Treatment of Rheumatoid Arthritis.

Bruton's tyrosine kinase (BTK) is a promising drug target for the treatment of multiple diseases, such as B-cell malignances, asthma, and rheumatoid arthritis. A series of novel aminotriazines were identified as highly selective inhibitors of BTK by a scaffold-hopping approach. Subsequent SAR studies of this series using two conformationally different BTK proteins, an activated form of BTK and an unactivated form of BTK, led to the discovery of a highly selective BTK inhibitor, 4b. With significant efficacy in models in vivo and good ADME and safety profiles, 4b was advanced into preclinical studies.

Protective effects of Paederia scandens extract on rheumatoid arthritis mouse model by modulating gut microbiota.

ETHNOPHARMACOLOGICAL RELEVANCE: Paederia scandens (Lour.) Merr. (P. scandens) has been traditionally used to treat the pain of rheumatism. AIM OF THE STUDY: The purpose of this study was to investigate the possible influences of P. scandens on the progression of rheumatoid arthritis (RA), inflammatory responses and gut bacterial communities in RA mouse model. MATERIALS AND METHODS: collagen-induced arthritis (CIA) mice were orally administered with P. scandens extract (PSE) for 24 days. Then, pro-inflammatory cytokine levels in the serum were measured, and gut microbiota was examined with Illumina HiSeq. RESULTS: Compared with the vehicle group, PSE significantly inhibited paw swelling and reduced arthritis score. Histological examination of ankle soft tissue of demonstrated PSE effectively inhibited the tissue fibrosis and inflammatory cell infiltration. The increased serum levels of TNF-α, IL-1ß, IL-6, IL-7, and IL-23 in RA mice were significantly suppressed by PSE. Moreover, PSE treatment help restore gut microbial ecosystem altered in RA mice including decreasing relative abundance of inflammatory related microorganisms, Desulfovibrio, Mucispirillum, Helicobacter, and Lachnospiraceae. CONCLUSION: These results suggest that PSE has therapeutic effects in RA mice with CIA, showing the potential as anti-arthritis reagent.

Microbiota and arthritis: correlations or cause?

PURPOSE OF REVIEW: The microorganisms that colonise our bodies, the commensal 'microbiota', respond to changes in our behaviour and environment, and can also profoundly affect our health. We can now investigate these organisms with unprecedented depth and precision, revealing that they may contribute to the pathogenesis of diseases including arthritis. Here we discuss the changes occurring in the microbiota in people with arthritis, and how manipulation of the microbiota may provide an additional pathway for therapy. RECENT FINDINGS: We highlight two important aspects of the recent literature. First we describe changes in the microbiota identified in people with arthritis; these correlations give insights into the microbial changes that may contribute to symptoms of arthritis. We then discuss attempts to ameliorate arthritis by manipulating the microbiota. This is a rapidly developing area of research. There are tantalising hints that interventions targeting the microbiota may become therapeutically viable for some types of inflammatory arthritis. SUMMARY: Our commensal microbial communities respond to changes in our health, and are altered in people with arthritis. Understanding the complex relationships between the microbiota and the body may enable us to deliberately manipulate these organisms and provide additional therapeutic options for people with arthritis.

Evaluation of bone targeting salmon calcitonin analogues in rats developing osteoporosis and adjuvant arthritis.

Synthetic analogues of the peptide hormone calcitonin have been used in medicine as biologic drug therapies for decades, to treat pathological conditions of excessive bone turnover, such as osteoporosis, where more bones are removed than replaced during bone remodeling. Osteoporosis and other chronic skeletal diseases, including inflammatory arthritis, exact a substantial and growing toll on aging populations worldwide however they respond poor to synthetic biologic drug therapy, due in part to the rapid half-life of elimination, which for calcitonin is 43 minutes. To address those shortcomings, we have developed and synthesized bone-targeting variants of calcitonin as a targeted drug delivery strategy, by conjugation to bisphosphonate drug bone-seeking functional groups in highly specific reaction conditions. To evaluate their in vivo efficacy, bisphosphonate-mediated bone targeting with PEGylated (polyethylene glycol conjugated) and non-PEGylated salmon calcitonin analogues were synthesized and dose escalation was performed in female rats developing Osteoporosis. The bone-targeting calcitonin analogues were also tested in a separate cohort of male rats developing adjuvant-induced arthritis. Ovariectomized female rats developing Osteoporosis were administered daily sub-cutaneous injection of analogues equivalent to 5, 10 and 20 IU/kg of calcitonin for 3 months. Adjuvant arthritis was developed in male rats by administering Mycobacterium butyricum through tail base injection. Daily sub-cutaneous injection of analogues equivalent to 20 IU/kg of calcitonin was administered and the rats were measured for visible signs of inflammation to a 21 day endpoint. In both studies, the effect of drug intervention upon bone volume and bone mineral density (BMD) was assessed by measuring the trabecular bone volume percentage and BMD at the proximal tibial metaphysis using in vivo micro-computed tomography. With dose escalation studies, only bone targeting analogue dosed groups showed a trend towards increased BMD and bone volume at 4, 8 and 12 weeks. Significant preservation of bone volume and BMD as evidenced by nonsignificant (P<0.05) loss of bone volume and BMD at the end of 3 month study endpoint was seen in animals dosed with 20 IU/kg of calcitonin compounds. Similarly, in case of adjuvant-induced arthritis rats, there was a significant increase (P<0.05) in bone volume and BMD in calcitonin-bisphosphonate and calcitonin-PEG-bisphosphonate treated groups at 21 days compared to the baseline values. Improved efficacy in terms of preserving bone volume and BMD in Osteoporosis, and in rats developing adjuvant-induced arthritis, by these analogues suggests their potential as new drug candidates for further evaluation to determine their usefulness in bone diseases characterized by excessive bone resorption.

Lactobacillus casei and Lactobacillus acidophilus regulate inflammatory pathway and improve antioxidant status in collagen-induced arthritic rats.

In view of well-established immunomodulatory properties of Lactobacillus, present investigation was carried out to evaluate antioxidant and anti-inflammatory potential of Lactobacillus casei and Lactobacillus acidophilus, against inflammatory pathway and oxidative stress developed in an experimental model of arthritis. Collagen-induced arthritis (CIA) model was used. Oral administration of L. casei, L. acidophilus, standard antiarthritic drug indomethacin, and vehicle were started after induced arthritis and continued up to day 28. Interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-1ß, IL-17, IL-4, and IL-10 levels were estimated in serum. In parallel, oxidative stress parameters were also measured from synovial effsuate. All rats were graded for arthritis score at the end of each week. L. casei, L. acidophilus, and indomethacin treatment significantly downregulated proinflammatory and upregulated anti-inflammatory cytokines at P<0.0001. They have significantly decreased oxidative stress in synovial effsuate (P<0.0001) and also arthritis score (P<0.05). Protection provided by L. casei and L. acidophilus was more pronounced than that of indomethacin. These lines of evidence suggest that L. casei and L. acidophilus exert potent protective effect against CIA. It further establishes effective anti-inflammatory and antioxidant properties of Lactobacillus. However, additional clinical investigations are needed to prove the efficacy of Lactobacillus in treatment/management of rheumatoid arthritis.

Celastrus treatment modulates antigen-induced gene expression in lymphoid cells of arthritic rats.

Rheumatoid arthritis (RA) is a debilitating autoimmune disease of global prevalence and the disease process primarily targets the synovial joints. Despite improvements in the treatment of RA over the past decade, there still is a need for new therapeutic agents that are efficacious, less expensive, and free of severe adverse reactions. Celastrus has been used in China for centuries for the treatment of rheumatic diseases. Furthermore, we previously reported that ethanol extract of Celastrus aculeatus Merr. (Celastrus) attenuates adjuvant-induced arthritis (AA) in rats. However, the mechanisms underlying the anti-arthritic activity of Celastrus have not yet been fully defined. We reasoned that microarray analysis might offer useful insights into the pathways and molecules targeted by Celastrus. We compared the gene expression profiles of the draining lymph node cells (LNC) of Celastrus-treated (Tc) versus water-treated (Tw) rats, and each group with untreated arthritic rats (T(0)). LNC were restimulated with mycobacterial heat shock protein-65 (Bhsp65). We identified 104 differentially expressed genes (DEG) (8 upregulated, 96 downregulated) when comparing Tc with T(0) rats, in contrast to 28 (12 upregulated, 16 downregulated) when comparing Tw and T(0) rats. Further, 20 genes (6 upregulated, 14 downregulated) were shared by both Tw and Tc groups. Thus, Celastrus treatment (Tc) significantly downregulated a large proportion of genes compared to controls (Tw). The DEG were mainly associated with the processes of immune response, cell proliferation and apoptosis, and cell signaling. These results provide novel insights into the mechanism of Celastrus anti-arthritic activity, and unravel potential therapeutic targets for arthritis.

RANKL-targeted therapy inhibits bone resorption in experimental Staphylococcus aureus-induced arthritis.

INTRODUCTION: Bacterial arthritis causes rapidly progressing joint destruction in humans. We have shown that addition of bisphosphonates or corticosteroids to conventional antimicrobial agents decreases the activity of osteoclasts, thereby reducing bone destruction. Here we assess the effect of RANKL-targeted treatments using soluble receptor decoy and osteprotegerin (OPG) on the course and outcome of staphylococcal arthritis. METHODS: Treatment was initiated 3 days after Staphylococcus aureus inoculation and included RANK-Fc, OPG-Fc, and OPG-Fc in combination with antibiotics. Control groups were treated with antibiotics, huFc, and PBS. Joints were evaluated for clinical signs of arthritis and histologically for bone and cartilage destruction. Bone mineral density (BMD) was evaluated using a peripheral quantitative computed tomography. Circulating markers of bone metabolism, inflammatory cytokines, and chemokines were analyzed in each group. RESULTS: Mice treated with RANK-Fc or OPG-Fc in combination with antibiotics preserved total BMD and trabecular bone as compared to huFc or antibiotics. Treatment with RANK-Fc or OPG-Fc diminished the levels of bone resorption markers (osteocalcin, CTX-I, and TRACP5b). Neither RANK-Fc nor OPG-Fc influenced significantly the frequency and severity of arthritis. CONCLUSIONS: Inhibition of RANKL signalling efficiently prevents bone loss in the mouse model of bacterial arthritis even when started in the overt phase of infection.

Modulation of SERCA in the chronic phase of adjuvant arthritis as a possible adaptation mechanism of redox imbalance.

Adjuvant arthritis (AA) is a condition that involves systemic oxidative stress. Unexpectedly, it was found that sarcoplasmic reticulum Ca(2 +)-ATPase (SERCA) activity was elevated in muscles of rats with AA compared to controls, suggesting possible conformational changes in the enzyme. There was no alteration in the nucleotide binding site but rather in the transmembrane domain according to the tryptophan polar/non-polar fluorescence ratio. Higher relative expression of SERCA, higher content of nitrotyrosine but no increase in phospholipid oxidation in AA SR was found. In vitro treatments of SR with HOCl showed that in AA animals SERCA activity was more susceptible to oxidative stress, but SR phospholipids were more resistant and SERCA could also be activated by phosphatidic acid. It was concluded that increased SERCA activity in AA was due to increased levels of SERCA protein and structural changes to the protein, probably induced by direct and specific oxidation involving reactive nitrogen species.

Pro-inflammatory activity in rats of thiocyanate, a metabolite of the hydrocyanic acid inhaled from tobacco smoke.

OBJECTIVE: To seek a mechanism linking tobacco smoking with the increased incidence and severity of rheumatoid arthritis, deduced from many retrospective surveys, by studying arthritis/fibrosis development in rats. METHODS: Rats (>300) received low levels of sodium/potassium thiocyanate (10 or 25 mmol/l) in their drinking water to raise their blood thiocyanate levels, mimicking the elevated levels of blood, salivary and urinary thiocyanate found in smokers. RESULTS: Thiocyanate supplements increased the severity of experimental arthritis induced by tailbase injection of (1) Freund's complete adjuvants (mycobacteria plus various adjuvant-active oils), (2) collagen type-II with Freund's incomplete adjuvant (no mycobacteria), (3) the synthetic lipid amine, avridine in an oil and (4) the natural hydrocarbons squalene (C(30)H(50)) and pristane (C(19)H(40)). This pro-arthritic effect was independent of sex, rat strain or changing diet and housing facilities. Thiocyanate supplements also amplified the acute/persisting inflammatory responses to paw injections of pristane, zymosan and microcrystalline hydroxyapatite. Iodide salts also mimicked some of these effects of thiocyanate. CONCLUSION: Thiocyanate, a detoxication product of HCN present in tobacco smoke, increased (or even induced) inflammatory responses to several agents causing arthritis or fibrotic inflammation in rats. It, therefore, can act as a co-arthritigen, or 'virulence factor' and could be a therapeutic target to reduce arthritis expression and morbidity.

In vivo efficacy of moxifloxacin compared with cloxacillin and vancomycin in a Staphylococcus aureus rabbit arthritis experimental model.

We investigated the efficacies of moxifloxacin, cloxacillin, and vancomycin in a rabbit model of Staphylococcus aureus arthritis. No significant difference between therapeutic regimens was observed after a 7-day treatment. Oral moxifloxacin could be a suitable alternative to standard parenteral therapy for S. aureus arthritis.

Enhanced Th1 response to Staphylococcus aureus infection in human lactoferrin-transgenic mice.

Lactoferrin (Lf) is an iron-binding protein of external secretions and neutrophil secondary granules with antimicrobial and immunomodulatory activities. To further define these properties of Lf, we have investigated the response to Staphylococcus aureus infection in transgenic mice carrying a functional human Lf gene. The transgenic mice cleared bacteria significantly better than congenic littermates, associated with a trend to reduced incidence of arthritis, septicemia, and mortality. We identified two pathways by which S. aureus clearance was enhanced. First, human Lf directly inhibited the growth of S. aureus LS-1 in vitro. Second, S. aureus-infected transgenic mice exhibited enhanced Th1 immune polarization. Thus, spleen cells from infected transgenic mice produced higher levels of TNF-alpha and IFN-gamma and less IL-5 and IL-10 upon stimulation ex vivo with the exotoxin toxic shock syndrome toxin-1 compared with congenic controls. To confirm that these effects of Lf transgene expression could occur in the absence of live bacterial infection, we also showed that Lf-transgenic DBA/1 mice exhibited enhanced severity of collagen-induced arthritis, an established model of Th1-induced articular inflammation. Higher levels of stainable iron in the spleens of transgenic mice correlated with human Lf distribution, but all other parameters of iron metabolism did not differ between transgenic mice and wild-type littermates. These results demonstrate that human Lf can mediate both antimicrobial and immunomodulatory activities with downstream effects on the outcome of immune pathology in infectious and inflammatory disease.

Sirolimus (rapamycin, Rapamune) and combination therapy with cyclosporin A in the rat developing adjuvant arthritis model: correlation with blood levels and the effects of different oral formulations.

OBJECTIVE AND DESIGN: To determine whole blood levels of sirolimus, a macrolide antibiotic in the rat developing adjuvant arthritis (AA) model after dosing orally with two different vehicles, and whether combinational doses of sirolimus and cyclosporin A (CsA) produced additive or synergistic inhibitory effects in this model. MATERIAL: Male Lewis rats (150-180g). TREATMENT: Arthritis was induced by the injection (0.5 mg/ rat) of heat-killed Mycobacterium butyricum suspended in light mineral oil. Drugs were administered orally either in fine suspension (0.5% Tween 80) or in emulsion (phosal 50 PG in 1% Tween 80) at doses of 0.1 to 5 mg/kg in a 7 day, MWF or daily regimen. METHOD: Paw volumes (ml) were measured by automated mercury plethysmograph and sirolimus concentrations in whole blood were quantitated by liquid chromatography/ mass spectroscopy. RESULTS: At 72h (7 days after adjuvant) after receiving the third oral dose (4.5 mg/kg p.o.), the phosal vehicle resulted in higher sirolimus blood levels (2.5 ng/ml) than in Tween 80 (1.6 ng/ml). After the rats received the last oral dose on day 14, (7 total doses of sirolimus at 4.5 mg/kg) the sirolimus blood levels (2h after the last dose) were about 2 times higher for the phosal dosed rats (9.8 ng/ml) compared to Tween 80 dosed rats (4.6ng/ml). Even 24h after the last dose, sirolimus blood levels were still elevated in the phosal dosed rats (0.8 ng/ml) relative to 0.5% Tween 80 dosed rats (0.5 ng/ml). At day 16 in the rat developing model, sirolimus, when given in phosal vehicle, produced an ED50 of 0.28 mg/ kg (i.e. inhibition of uninjected paw edema) that was about 5.5 times lower than using 0.5% Tween 80 as the suspending agent (ED50 = 1.6mg/kg). When combining sirolimus and CsA using precalculated doses for producing an additive effect in this adjuvant model, an additive inhibitory effect on uninjected paw edema was observed at equal combinational doses of 0.5 and 2 mg/kg, respectively. CONCLUSIONS: The phosal vehicle used in administering sirolimus increases the absorption and whole blood levels in the rat and the elevated blood levels correlated positively with the therapeutic effect in the rat developing AA model. In addition, combination therapy using sirolimus and CsA produced an additive effect in rat developing AA.

Desferrioxamine potentiated SOD antiinflammatory activity in rat adjuvant arthritis: role of iron and bacterial toxins.

In this paper we studied the modulating inflammatory activity of iron in the adjuvant arthritis, taking indomethacin as a standard antiinflammatory drug and a superoxide dismutase derivative (MPEG-SOD) as a scavenger of free radicals. Moreover, we evaluated the changes in potential intestinal pathogens requiring iron for growth, in order to study the role of bacteria in the altered gastrointestinal functions observed during arthritis. We observed a 50% arthritis inhibition on the 14th day with MPEG-SOD plus desferrioxamine, a significant decrease in serum iron in arthritic rats compared to controls, and a significant Cl. perfringens increase on the 28th day in the presence of MPEG-SOD. Our data demonstrate that hypoferremia, in arthritis, is a protective mechanism overall in the early phase and could protect the intestinal tract by inhibiting the development of potential pathogens.

AHR-15010--a novel anti-arthritic agent.

AHR-15010 (3-(2-methoxyphenoxy)-1,2-propanediol bissulphamate ester) is a compound of novel structure that displays anti-arthritic activity in adjuvant arthritis in rats. When given orally from days 18 through day 50, (excluding weekends) after adjuvant injection, AHR-15010, at doses of 3.16 to 100 mg kg-1, produced significant anti-inflammatory activity and reduced the severity of the hind paw joint lesions as monitored by X-ray analysis. AHR-15010, however, has no acute anti-inflammatory activity in the Evans Blue-carrageenan pleural effusion assay in rats, has no analgesic activity in mice, and has no activity in a classic, delayed-type, hypersensitivity assay in mice or in a cotton pellet granuloma test in rats. These data, in conjunction with biochemical data showing that AHR-15010 has no prostaglandin synthetase inhibiting activity suggest that AHR-15010 is an anti-arthritic with a unique mechanism of action. AHR-15010 is a carbonic anhydrase inhibitor. Data are presented that suggest that AHR-15010 and acetazolamide, a prototype carbonic anhydrase inhibitor, may present novel approaches to the treatment of arthritis.

Detection of Mycoplasma pulmonis in arthritic joints of rats by indirect immunoperoxidase staining.

Neonatal and 8-week-old rats were inoculated with Mycoplasma pulmonis. A portion of the animals developed polyarthritis. Indirect immunoperoxidase staining was used to identify the localization of M. pulmonis within arthritic joints. M. pulmonis antigen was most often observed within cartilage in the neonatal group and in synovial tissue in the 8-week-old group.

Suppressive effect of Escherichia coli on adjuvant-induced arthritis in germ-free rats.

Our previous finding, that germ-free F344 rats develop severe adjuvant-induced arthritis, whereas specific pathogen-free rats develop mild disease, prompted us to investigate the role of bacterial flora in promoting the development of this disease. Germ-free rats given Escherichia coli experienced disease suppression. Germ-free rats treated with 3 strains of Lactobacillus experienced an enhancement of the disease, although it was not significant. Germ-free rats treated with a combination of E coli and lactobacilli had disease suppression similar to that of E coli monoassociated rats. Thus, these findings suggest that E coli may play a dominant role in modulating the development of the disease in this particular strain of F344 rats, possibly through its lipopolysaccharide (as evidenced by positive results on limulus tests). These findings also suggest that microflora play an important role in modifying the development of joint disease.

Rat polyarthritis: induction with adjuvants constituted with mycobacteria (and oils) from the environment.

Mycobacteria inhabiting plants, soils and water can cause arthritis in rats. The list of arthritogenic mycobacteria from animal sources must also be extended. The arthritogenic activity is present in dead bacteria and resists extraction into ethanol-ether (1:1 v/v). Polyarthritis is only induced in conjunction with certain (oily) lipids = coarthritogens: some of these lipids are present in/on skin, intestines, etc. Isostearic acid is also a coarthritogen. Preliminary observations suggest the leprosy bacillus (M. leprae) is not arthritogenic but may confer immunity to the M. tuberculosis arthritogen. Some adjuvant-active corynebacteria/propionibacteria did not cause polyarthritis in 2 rat strains (DA, PVG) responding vigorously to mycobacterial arthritogens.