Proliferative synovitis in rabbit knee joints induced by antigen and preformed immune complexes

Modulation of immune function by dietary lectins in rheumatoid arthritis

Despite the almost universal clinical observation that inflammation of the gut is frequently associated with inflammation of the joints and vice versa, the nature of this relationship remains elusive. In the present review, we provide evidence for how the interaction of dietary lectins with enterocytes and lymphocytes may facilitate the translocation of both dietary and gut-derived pathogenic antigens to peripheral tissues, which in turn causes persistent peripheral antigenic stimulation. In genetically susceptible individuals, this antigenic stimulation may ultimately result in the expression of overt rheumatoid arthritis (RA) via molecular mimicry, a process whereby foreign peptides, similar in structure to endogenous peptides, may cause antibodies or T-lymphocytes to cross-react with both foreign and endogenous peptides and thereby break immunological tolerance. By eliminating dietary elements, particularly lectins, which adversely influence both enterocyte and lymphocyte structure and function, it is proposed that the peripheral antigenic stimulus (both pathogenic and dietary) will be reduced and thereby result in a diminution of disease symptoms in certain patients with RA.

Biomechanical and morphological studies on osseointegration in immunological arthritis in rabbits

The biomechanics and morphology of the interface between bone tissue and threaded, commercially pure titanium implants were studied i an experimental model of monoarticular arthritis in New Zealand white rabbits (n = 8). Two of the eight rabbits died before evaluation. Immunisation with bovine serum albumin (BSA) and repeated intra-articular injections with BSA in one knee joint elicited an immune response and clinical signs of inflammation. The opposite joint was injected with saline. Three implants were inserted intra-articularly in the lateral femoral condyle in each joint. After a period of six weeks the stability of two of the three implants was evaluated by pull-out and torsion tests using a standardised biomechanical model. The rabbits were killed by perfusion fixation, and the implants and surrounding tissue were retrieved en bloc for histological analysis. The amount of bone, the degree of bone apposition, and the biomechanical evaluation showed that the absolute mechanical capacity of anchorage was not significantly reduced on the arthritic side compared with the control knees. These results indicate that it might be possible to obtain osseointegration in juxta-articular bone despite local joint inflammation.

Tissue response to titanium implants in experimental antigen-induced arthritis

The healing of threaded, non-alloyed titanium implants in bone was studied in an experimental model of monoarticular arthritis in New Zealand white rabbits. Immunization with bovine serum albumin (BSA) and repeated intra-articular injections with BSA elicited an immune response and clinical signs of inflammation. Implants were inserted and 6 wk after surgery, with full weight-bearing, the rabbits were killed by perfusion fixation. Light microscopic morphometry showed that the cartilage was thinner and the subchondral bone had a lower density in the arthritic joints compared to the control side. The titanium implants in the arthritic joints had a lesser degree of mineralized bone-implant contact and surrounding bone than the implants inserted in control joints. The present study shows that the healing of titanium implants in the rabbit knee joint is impaired in experimental immunologic arthritis. This model may be useful for the study of biomaterial-tissue interactions under pathological conditions.

Leukotriene B4, interleukin 1 and leucocyte accumulation in titanium and PTFE chambers after implantation in the rat abdominal wall

The inflammatory reaction elicited after implantation of non-biologic materials was studied by analysis of the exudate in pure titanium or polytetrafluorethylene chambers 1-9 d after insertion in the abdominal wall of the rat. In chambers made of pure titanium, the number of leucocytes increased about twofold from 1.8 x 10(6)/ml to 4.1 x 10(6)/ml between 24 h and 6 d, whereas a larger increase from 2.1 x 10(6)/ml to 8.3 x 10(6)/ml was observed in the polytetrafluorethylene chambers. Irrespective of implant material, polymorphonuclear granulocytes constituted the vast majority of leucocytes (greater than 81%). After 24 h the leukotriene B4 content was slightly higher in polytetrafluorethylene chambers than in titanium chambers. In contrast to the titanium chambers, a marked increase in leukotriene B4 levels was detected in polytetrafluorethylene chambers 6 d after insertion, whereas the greatest amount of leukotriene B4 in titanium chambers was measured at 9 d. Interleukin 1 was only detected in both types of chambers after 6 d. The present study, together with previous findings, shows that the materials used in this study elicit different degrees of inflammatory reactions in the chamber exudate. Since the number of leucocytes in the exudate retrieved from the chambers correlated well with the leukotriene B4 levels, it is suggested that leukotriene B4, but not interleukin 1, may be an important mediator for polymorphonuclear granulocyte migration into the implant-tissue interface.(ABSTRACT TRUNCATED AT 250 WORDS)

Neutrophil activation by IgE-containing circulating immune complexes of patients with connective tissue diseases

In an earlier study, we reported IgE-containing circulating immune complexes (CICs) in 66.6% of the patients with rheumatoid arthritis who were studied, especially in those with extra-articular manifestations. The present study was undertaken to examine the possible role of these immune complexes in inflammatory cell activation. Twelve patients with classic or definite rheumatoid arthritis, two with primary Sjögren's syndrome, and three patients with systemic lupus erythematosus were studied. Of these 17 patients, 10 were IgE-containing CIC positive, and seven patients were IgE-containing CIC negative. Polyethylene glycol-precipitated IgE-containing CICs and IgG-containing CICs of these patients were coated on plastic wells and incubated with suspensions of neutrophils. As a parameter of cell activation, superoxide release (SOR) was measured by cytochrome C reduction in the supernatant after 30, 60, and 90 minutes. There was a significant SOR up to 38% of the zymosan control when IgE-containing CICs were incubated with neutrophils. Furthermore, there was a significant correlation between the level of IgE-containing CICs and the amount of SOR, but not between the level of IgG-containing CICs and the amount of SOR. These results suggest a possible role for IgE-containing CICs in the activation of inflammatory cells in connective tissue diseases.

Joint fluid leukocyte activation by preformed immune complexes

Acute synovitis was induced in rabbit knee joints by intraarticular injection of preformed bovine serum albumin (BSA) -anti BSA immune complexes (ICs). Polymorphonuclear granulocytes (PMNGs) which had migrated into joints injected with ICs were degranulated and contained ICs as revealed by electron microscopy and were activated as revealed by the measurement of chemiluminescence (CL). In contrast, leukocytes from control joints injected with BSA and normal rabbit serum as well as glycogen-elicited peritoneal leukocytes did not display any morphological changes and did not show CL. Compared to cells from other sources, leukocytes from IC joints showed a decreased CL response when stimulated in vitro with ICs but not with opsonized zymosan, suggesting a stimulus-specific modification of the PMNG responsiveness. Inhibition experiments showed that oxygen radicals and formation of arachidonate metabolites, mainly of the lipoxygenase pathway, were involved in the CL response of the IC-stimulated joint fluid PMNGs. Our observations on morphology, activity, and responsiveness of emigrated cells from the various sources suggest, together with previous observations, that the reaction of leukocytes in IC-induced synovitis consists of an initial migration phase not related to an increased CL and a subsequent activation phase characterized by degranulation, phagocytosis of ICs and increased CL.