Responses of the rat immune system to arthritogenic adjuvant oil

In vivo biological response to vitamin E and vitamin-E-doped polyethylene

BACKGROUND

Cross-linking has decreased the wear of ultra-high molecular weight polyethylene, a cause of osteolysis leading to total joint replacement failure. Compared with melting or annealing, doping cross-linked ultra-high molecular weight polyethylene with vitamin E stabilizes free radicals from irradiation while maintaining mechanical properties and wear resistance. This study was done to determine the local tissue effects of free vitamin E and vitamin E eluted from ultra-high molecular weight polyethylene implants in the joint space.

METHODS

Three studies were performed. First, pure vitamin E and solubilized vitamin E were injected into rabbit knees to simulate vitamin-E elution from radiation cross-linked ultra-high molecular weight polyethylene; second, vitamin-E-doped, irradiated ultra-high molecular weight polyethylene plugs were implanted into dorsal subcutaneous pouches of rabbits to determine the local effects of vitamin-E elution from radiation cross-linked ultra-high molecular weight polyethylene; and, third, two groups of vitamin-E-doped, irradiated acetabular liners (high surface and uniform vitamin-E concentration profiles) were compared with undoped, control ultra-high molecular weight polyethylene liners in a canine model of total hip replacement to determine the effect of possible vitamin-E elution on bone ingrowth and the local tissue response to it in a load-bearing environment.

RESULTS

Injection of solubilized vitamin E resulted in histologically normal surrounding soft tissue at both two and twelve-week follow-up intervals, while injection of pure vitamin E resulted in acute and chronic inflammation at the time of the two-week follow-up. Both control and vitamin-E-doped subcutaneous plugs showed inflammation associated with surgery at two weeks of follow-up, but showed stable fibrous encapsulation without inflammation at twelve weeks of follow-up. In the canine total hip replacement model, there was no qualitative difference in local tissue appearance and no significant difference in the percent bone ingrowth and the percent bone density between the control and vitamin-E groups.

CONCLUSIONS

These investigations showed that vitamin-E-doped ultra-high molecular weight polyethylene plugs and total hip replacement components are well tolerated in both a small and a large-animal model with no observed adverse effects on the surrounding tissues at twelve weeks of follow-up.

Common vaccinations among adults do not increase the risk of developing rheumatoid arthritis: results from the Swedish EIRA study

OBJECTIVE

To investigate the association between vaccinations in adults and the risk of developing rheumatoid arthritis (RA).

METHODS

Data from the Swedish population-based Epidemiological Investigation of RA case-control study encompassing 1998 incident cases of RA aged 18-70 years and 2252 randomly selected controls matched for age, sex and residency were analysed. Those vaccinated within 5 years before disease onset were compared with those not vaccinated by calculating OR with 95% CI.

RESULTS

Vaccinations neither increased the risk of RA overall (OR 1.0, 95% CI 0.9 to 1.1) nor the risk of two major subgroups of RA (antibodies to citrullinated peptide-positive (ACPA-positive) and ACPA-negative disease). Furthermore, vaccinations did not increase the risk of RA in smokers or carriers of HLA-DRB1 shared epitope alleles, two groups with established risk factors for RA.

CONCLUSIONS

In this case-control study of incident cases of newly diagnosed RA, no increased risk of RA following immunisation was observed for vaccinations overall or for any specific vaccination. This indicates that immunological provocation of adults with commonly used vaccines in their present form carries no risk of RA. These findings should be implemented among public healthcare providers in order to encourage vaccinations according to recommended national vaccination schedules.

Strain differences and the role for HSP47 and HSP70 in adjuvant arthritis in rats

Because of high sequence homology between microbial and endogenous heat shock proteins (HSP), immunological cross-reactivity to microbial HSP has been suggested as a possible cause of the development of autoimmune diseases, such as rheumatoid arthritis. The present study aimed to determine a potential role of HSP47, a molecular chaperone involved in the synthesis and assembly of collagen molecules, and microbial HSP71 (mHSP71) in adjuvant arthritis (AA) in two rat strains: Dark Agouti (DA), susceptible to AA induction and Albino Oxford (AO), which is resistant to AA induction. Immunization with complete Freund's adjuvant (CFA) induced an increased expression of HSP47 in joints of DA rats, which exhibited severe clinical signs of AA at the time of disease peak, while this protein was not detectable in joints of AO rats. In contrast, no strain differences in HSP72 (rat analogue of mHSP71) expressions in joints were observed. The increased levels of anti-HSP47 antibodies were detected in sera of DA rats during the AA peak, while the immunization with CFA increased levels of anti-mHSP71 antibodies in sera of AO rats. HSP47 and mHSP71 reduced proliferation of draining inguinal lymph node cells (LNC) in resistant AO rat strain, leading to a hypothesis that both HSP participated in AA control. Finally, mHSP71 potentiated the apoptotic response of LNC in susceptible DA rat strain. In conclusion, our findings indicate involvement of HSP47 in the development of AA in the rat, and point out to the regulatory role for both HSP47 and mHSP71.

Pristane-induced arthritis in the rat

A chronic relapsing arthritis develops after a single subcutaneous injection of small amounts of pristane; the pristane induced arthritis (PIA) model in the rat. PIA is characterized by a sudden onset of disease 2 wk after induction. The main pathological features of PIA include edema accompanied by an acute phase response, infiltration into the joint of mononuclear and polymorphonuclear cells, pannus formation, and erosion of cartilage and bone. PIA is a disease that is largely T-cell dependent that can be adoptively transferred by activated CD4+ T-cells. PIA in rats is followed clinically by macroscopic scoring and is characterized by an early acute phase of severe inflammation after onset that eventually gradually disappears to be followed by less severe relapsing phases of new inflamed joints and increasing cartilage erosion and joint deformity. PIA can be diagnosed by biochemical analyzes in plasma that reflects systemic inflammation (alpha1-acid glycoprotein (AGP) and IL-6) and cartilage erosion (COMP).

Adjuvant oil induces waves of arthritogenic lymph node cells prior to arthritis onset

A single intradermal injection of the adjuvant-oil squalene induces T cell mediated arthritis in DA rats. The chain of events leading from nonspecific provocation of the immune system to arthritis is largely unknown. Previous studies have demonstrated that lymph node (LN) cells are of pathogenic importance, i.e. cells from LNs draining the injection site can transfer arthritis to naïve DA rats. Recently we have demonstrated cellular uptake of adjuvant oil in draining lymph nodes but also that nondraining LNs become hyperplastic and harbour arthritogenic cells. Here, we aimed to determine from which time-point prior to arthritis onset arthritogenic cells appear in draining inguinal and nondraining axillary/brachial LNs, respectively. We demonstrated that the ability to transfer arthritis was strongly dependent on the time-point after adjuvant-injection with clear-cut differences between draining and nondraining LN cells. Cells harvested at day 5 postinjection (p.i) were not able to transfer arthritis, while at day 8 p.i, a first wave of arthritogenic cells appeared in draining LNs. The ability to transfer arthritis was associated with a pro-inflammatory cytokine profile as indicated by the IL-1beta and IFNgamma expression in cells from draining LNs. Subsequently, at day 11 p.i., just before arthritis onset, arthritogenic cells appeared also in nondraining LNs. These results shed new light on the induction of arthritic diseases, implicating a two step mechanism for the development of pathogenic cells. Firstly, a pro-inflammatory burst in responding lymphoid organs leading to a local pool of arthritogenic cells and, secondly, a transmission of arthritogenecity to other LNs and precipitation of disease in peripheral joints.

Occupations and exposures in the work environment as determinants for rheumatoid arthritis

BACKGROUND AND AIMS

Several occupational categories have been associated with rheumatoid arthritis (RA); this study was conducted to further evaluate these associations.

METHODS

Lifelong occupational history together with exposure experiences were collected through a postal questionnaire answered by 293 incident cases and 1346 population based referents. Occupational determinants were evaluated through stratified and multivariate analyses; pooled analyses with previously gathered data on 422 prevalent cases and 858 referents were also performed.

RESULTS

In both materials, significantly increased logistic odds ratios (LORs) were seen for male conductors, freight and transport workers (LOR 17.8, 95% CI 1.5 to 207.8 and LOR 4.7, 95% CI 1.4 to 16.3, respectively), and farmers and farm workers (LOR 2.4, 95% CI 1.1 to 5.2, and LOR 2.2, 95% CI 1.3 to 3.5, respectively). Among women, increased LORs were seen in the separate and the pooled material for printmakers and process engravers (LOR 5.5, 95% CI 0.9 to 32.6, and LOR 3.0, 95% CI 0.9 to 10.3, respectively). Increased risks were seen in both materials for men exposed to asbestos (LOR 2.5, 95% CI 1.0 to 6.8, and LOR 1.6, 95% CI 0.8 to 3.3, respectively), and vibrations (LOR 2.0, 95% CI 0.9 to 4.4, and LOR 2.2, 95% CI 1.3 to 3.8, respectively). The risk for RA increased with increasing duration of exposure to vibrations and mineral dust, respectively.

CONCLUSIONS

There was evidence of a causal relation between exposures to vibrations and mineral dust and development of RA among men. Occupational factors seem to be aetiologically more important for men, and most occupations at risk involve multiple exposures. Several exposures associated with an increased risk for RA are frequent among farmers, and some of the occupations at risk include exposure to organic dust.

Oligodeoxynucleotides containing CpG motifs can induce T cell-dependent arthritis in rats

OBJECTIVE

To investigate whether CpG oligodeoxynucleotides (ODNs) can induce or accelerate arthritis in rats.

METHODS

The CpG-induced response was studied by recording joint inflammation, cell activation in draining lymph nodes, and levels of the acute-phase reactant alpha(1)-acid glycoprotein (AGP) in sera. The role of T cells was investigated by in vivo administration of monoclonal antibodies specific for the T cell receptor alpha/beta (TCRalpha/beta), followed by analysis of cell phenotypes by flow cytometry.

RESULTS

One intradermal injection of CpG ODN emulsified with Freund's incomplete adjuvant (IFA) induced arthritis in LEW and LEW.1AV1 rats, while the control ODN sequence without CpG motifs or IFA alone did not trigger disease. The CpG/IFA and control-ODN/IFA injections induced lymphoplasia as well as elevated levels of interleukin-1beta and interferon-gamma messenger RNA in lymph nodes. The arthritis was preceded by elevated levels of AGP in serum. In vivo administration of anti-TCRalpha/beta antibodies after disease induction caused decreased expression of the TCR-CD3 complex on circulating T cells and ameliorated the arthritis.

CONCLUSION

We demonstrated that injection with immunostimulatory CpG, both in phosphorothioate-modified and native forms, can induce a T cell-dependent joint-specific inflammation in LEW and LEW.1AV1 rat strains. This arthritis is preceded by signs of activation of the innate immune system. Since unmethylated CG dinucleotides are common in bacterial DNA but rare in mammalian DNA, our results indicate that exposure to bacterial DNA during infection may contribute to arthritis induction by amplifying the innate immune response.

Antigen inhibition of collagen-induced arthritis is associated with up-regulation of IL-4 mRNA and induction of Ox40 on T cells in draining lymph nodes

The addition of a foreign antigen to an inoculum completely inhibits the development of collagen-induced arthritis (CIA). However, the mechanism of this phenomenon, antigen -inhibition, is incompletely understood. Previous studies have demonstrated that the inhibition of arthritis is not mediated through suppression of the antibody response to cartilage antigens. In this paper we investigated cytokine mRNA levels in lymph nodes cells recovered 3, 7 or 16 days from animals immunized with either collagen II in IFA or OVA + collagen II in IFA. At day 7, but not at other time-points, IL-4 mRNA was up-regulated in the lymph nodes of OVA-inhibited non-arthritic animals compared to control animals which all developed arthritis. No significant differences between the two groups could be detected when expression of IFN-gamma, IL-2, TNF-alpha, IL-1beta or IL-10 mRNA was analysed. Flow cytometry analysis of draining lymph node cells demonstrated that the T cell marker Ox40 was up-regulated in the OVA-inhibited group. Our results indicate that the complete inhibition of CIA caused by addition of OVA to the collagen II inoculum is due to the presence of a TH2 environment resulting from an increased production of IL-4 mRNA and a parallel increase in Ox40+ T cells.