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Biomedical subjects

E R Pettipher

Publications and source records attributed to E R Pettipher.

31 records · Page 2Linked to original sources
PubMed1989

Cartilage proteoglycan depletion in acute and chronic antigen-induced arthritis.

We examined the kinetics of proteoglycan (PG) depletion in rabbits with antigen-induced arthritis. There was a rapid loss of PG from arthritic cartilage, reaching 35-40% at day 7. Thereafter, the rate of PG depletion declined, and by day 42, the maximum loss was 55-60%. The initial loss of PG was accompanied by the appearance of large amounts of sulfated glycosaminoglycans (GAGs) in the joint fluid (measured as total sulfated GAGs by dye binding and as keratan sulfate by radioimmunoassay). However, by day 14, the levels of sulfated GAGs in arthritic joint fluid declined to control levels, even though the cartilage demonstrated a sustained depletion of PG. The cartilage PG degradation observed in antigen-induced arthritis could also be produced in normal animals by a single intraarticular injection of recombinant interleukin-1. The acute loss of cartilage PG occurred independently of neutrophil accumulation, both in the case of antigen-induced arthritis and after injection of interleukin-1.

Animals↗
PubMed1989

Effect of indomethacin on swelling, lymphocyte influx, and cartilage proteoglycan depletion in experimental arthritis.

The effects of indomethacin on antigen induced arthritis in rabbits have been investigated. Arthritis was induced in the knee joints of sensitised rabbits by intra-articular injection of antigen. Swelling of the joints was measured for 14 days after antigen challenge, and groups of animals were killed on days 1, 7, or 14 for collection of synovial fluids and tissues. Indomethacin (1 mg/kg, three times daily) reduced joint swelling and the prostaglandin E2 concentrations in synovial fluid. In addition, indomethacin increased the loss of proteoglycan from articular cartilage and the numbers of lymphocytes in the inflamed synovial lining. These findings suggest that the symptomatic benefits of indomethacin and related drugs in inflammatory arthritis may be achieved at the expense of significant adverse effects on joint tissues.

Animals↗
PubMed1989

Pathogenesis and treatment of chronic arthritis.

Inflammatory and 'non-inflammatory' forms of arthritis affect a large proportion of the population and these diseases can often lead to disability. Although the pain of arthritis can be relieved to some extent by the peripherally acting aspirin-like drugs, the progression of disease leading to joint destruction is largely resistant to current drug therapy. The synovial joints of patients with rheumatoid arthritis are infiltrated with neutrophils, macrophages and lymphocytes and the resident cells become activated to degrade the cartilage and bone. The inflammatory and destructive changes that occur are brought about by the action of mediators or local hormones which are produced by a variety of cell-types. Lipid mediators, such as prostaglandins, contribute to the symptoms of arthritis while polypeptide cytokines, such as interleukin 1 and tumour necrosis factor, play a key role in joint destruction by activating the synovial cells and chondrocytes to release metalloproteinases, such as collagenase. Aspirin-like drugs inhibit the production of prostaglandins from inflamed tissues and thereby blunt the symptoms of arthritis. However, these drugs do not suppress the production of collagenase from connective tissue cells and, therefore, do not halt the degeneration of joint tissues.

Arthritis, Rheumatoid↗
PubMed1989

Arthritogenic actions of recombinant IL-1 and tumour necrosis factor alpha in the rabbit: evidence for synergistic interactions between cytokines in vivo.

Intra-articular injection of highly purified or recombinant interleukin 1 (IL-1) into the rabbit knee induces a transient synovitis with leucocytic infiltration into the synovial lining and joint cavity and loss of proteoglycan from articular cartilage. Tumour necrosis factor alpha (TNF-alpha), which has many of the actions of IL-1, in the dose range 50-5,000 ng induced infiltration of leucocytes into the joint but failed to cause significant proteoglycan loss from cartilage. The nature of the leucocytic infiltrate induced by intra-articular TNF-alpha was predominantly monocytic compared with the mixed polymorphonuclear (PMN)/monocytic infiltrate induced by IL-1. Neither cytokine induced the accumulation of significant numbers of lymphocytes. In addition, on a molar basis, TNF-alpha was significantly less active than IL-1 in causing cell accumulation in the joint. Injection of submaximal doses of IL-1 and TNF into the rabbit resulted in a marked synergy with respect to the accumulation of PMN. The conclusion from these studies is that TNF-alpha could contribute to the PMN accumulation in the human joint in rheumatoid arthritis but is unlikely to be important in the destruction of articular cartilage.

Animals↗
PubMed1988

Comparison of the in vivo inflammatory activities after intra-articular injection of natural and recombinant IL-1 alpha and IL-1 beta in the rabbit.

Comparison has been made of the in vivo pro-inflammatory activities or procine natural and human recombinant alpha and beta interleukin 1 (IL-1) after injection into the knee joints of rabbits. Both forms of pig IL-1 and human IL-1 were separately equiactive in vitro in stimulating rabbit synovial fibroblasts and articular chondrocytes to synthesize prostaglandin E2 (PGE2). Injection of IL-1 into the rabbit knee joint was not associated with swelling of the joint nor with the appearance of PGE2 in the synovial fluid. However, all preparations of IL-1 induced a dose-dependent increase in inflammatory leukocytes in the synovial lining and joint cavity. In addition, both the alpha and beta forms of IL-1 from both species caused loss of proteoglycan from the matrix of articular cartilage. This study demonstrates that both genetically distinct forms of IL-1 have the same range of inflammatory actions within the joint and that they have similar potencies in these respects.

Animals↗
PubMed1988

Leucocyte infiltration and cartilage proteoglycan loss in immune arthritis in the rabbit.

1. The relationship between phagocytic leucocyte infiltration and cartilage degradation in immune arthritis has been investigated in groups of normal and neutropenic rabbits. 2. Injection of antigen into the knee joints of sensitized control animals induced joint swelling, prostaglandin E2 (PGE2) synthesis, leucocyte accumulation and proteoglycan loss from articular cartilage. 3. Intravenous injection of nitrogen mustard caused a selective depletion of circulating neutrophils and monocytes with little or no effect on platelets or lymphocytes. In neutropenic animals challenged with antigen, there was virtually no joint swelling, PGE2 synthesis or leucocyte infiltration but cartilage proteoglycan loss was unchanged after 1 day and increased by day 4 compared to control animals. 4. The numbers of circulating leucocytes returned to normal 3-4 days after nitrogen mustard treatment and leucocyte infiltration occurred in antigen-challenged joints but this was not accompanied by joint swelling. Subsequent intra-articular injection of PGE2 did, however, cause swelling. 5. Lysosomal enzyme levels in arthritic joint fluids were measured. The levels of beta-glucuronidase, which is released by activated phagocytes, were decreased in neutropenic animals but the levels of N-acetyl-beta-glucosaminidase, which is a marker of tissue damage, were not changed by neutrophil depletion. 6. Intra-articular injections of the cytokine interleukin-1 (IL-1) induced a pattern of leucocyte infiltration and cartilage proteoglycan loss similar to that seen in immune arthritis. In neutropenic animals, IL-1 did not cause significant accumulation of leucocytes in the joint but the loss of proteoglycan from cartilage was unimpaired. 7. These results indicate that both leucocyte infiltration and prostaglandin synthesis are required for joint swelling but that tissue degradation is mediated by resident cells. It is likely that release of IL-1 by synovial cells stimulates the synthesis and activation of metalloproteinases which initiate the process of tissue degradation.

Animals↗
PubMed1988

Studies on interleukin-1-induced arthritis.

IL-1 induces PMN and monocyte infiltration when injected into rabbit knee joints (1). This transient synovitis is associated with depletion of proteoglycan from the articular cartilage matrix. However, it is not clear whether the cartilage proteoglycan depletion is dependent on the infiltrating leucocytes. Consequently, we have investigated the effect of intra-articular injection of interleukin-1 in rabbits depleted of circulating PMN and monocytes with nitrogen mustard.

Animals↗
PubMed1988

The relationship between cell-mediated immunity and cartilage degradation in antigen-induced arthritis in the rabbit.

The relative contributions of cellular and humoral immunity to cartilage destruction in chronic arthritis has been investigated in a model of chronic synovitis in the rabbit. In this model, antigen-induced arthritis, immunization with ovalbumin in Freund's complete adjuvant (FCA) followed by intra-articular injection of this protein produces a chronic synovitis associated with loss of proteoglycan from articular cartilage. In addition, the synovial lining cell population is metabolically activated. Similar treatment of animals immunized with ovalbumin in Freund's incomplete adjuvant (FIA) produced a resolving arthritis which initially (over the first 7 days) appears to be identical to that in FCA-immunized animals, apart from the lack of activation of synovial lining cells. Following this initial synovitis the joints return to apparent normality apart from a persistent 'low grade' synovitis consisting mainly of a plasma cell infiltrate. The most striking finding in the FIA-immunized animals is the rapid loss (greater than 30% by day 7) and recovery of proteoglycan from the matrix of articular cartilage. These findings show that the perpetuation of chronic destructive synovitis in the rabbit requires the presence of active cellular immunity.

Acid Phosphatase↗
PubMed1987

PAF-acether in chronic arthritis.

Platelet activating factor (PAF-acether) is a potent pro-inflammatory mediator. The possible involvement of this molecule in the pathogenesis of chronic erosive arthritis has been investigated using an animal model, antigen-induced arthritis in the rabbit, which closely resembles rheumatoid arthritis. The arthritic joint fluids from rabbits with antigen-induced arthritis contained low levels of PAF-acether in the acute stages of the disease. However, PAF-acether was not detectable in the chronic stages of the lesion. The biologically inactive precursor/metabolite of PAF-acether, lyso-PAF-acether, was detectable in both control and arthritic joint washes. However, the levels of lyso-PAF-acether in the arthritic joint fluids were significantly elevated above those of control in the acute stages of the disease, but not in the chronic stages. Intra-articular injection of PAF-acether at doses up to 100 times the levels detected in the acute stages of this model did not induce joint swelling or leucocyte accumulation in normal rabbits. This study suggest that PAF-acether may contribute to the acute phase of antigen-induced arthritis but is less likely to be involved in the chronic processes.

Animals↗
PubMed1986

Interleukin 1 induces leukocyte infiltration and cartilage proteoglycan degradation in the synovial joint.

Interleukin 1 (IL-1) is a polypeptide released by activated macrophages and is thought to be a key mediator of host responses to infection and inflammation. The availability of highly purified and recombinant material has now permitted the evaluation of IL-1 as a mediator of chronic inflammatory processes in vivo. We have demonstrated that intraarticular injection of IL-1 into rabbit knee joints induces the accumulation of polymorphonuclear and mononuclear leukocytes in the joint space and the loss of proteoglycan from the articular cartilage. The effects on cartilage could not be explained solely by the presence of leukocytes, since injections of endotoxin also stimulated leukocyte accumulation in the joint but had no effect on proteoglycan loss. Responses to IL-1 were not associated with increased production of the icosanoids prostaglandin E2 or leukotriene B4 and were not reduced by an inhibitor of their synthesis. The pattern of leukocyte infiltration and cartilage breakdown 24 hr after IL-1 injection was similar to that seen in animals with antigen-induced arthritis of 1 week's duration. These observations support the hypothesis that IL-1 acts directly to mediate the erosive processes of chronic arthritis.

Animals↗