The involvement of the alpha4-integrin very late activation antigen 4 and vascular cell adhesion molecule-1 (VCAM-1) in leukocyte trafficking into the airways of ovalbumin (OA)-sensitized and OA-challenged mice was investigated using in vivo administration of anti-alpha4 monoclonal antibodies (mAb) PS/2, R1-2, and M/K-2.7 (MK2), specific for VCAM-1. VCAM-1 was upregulated on endothelial cells in lung tissue after OA inhalation. PS/2, R1-2, or MK2 significantly inhibited the recruitment of eosinophils and lymphocytes into the bronchoalveolar lavage (BAL) fluid and decreased inflammation in the lung tissues. Escalating in vivo doses of PS/2 or MK2 increased circulating levels of rat immunoglobulin G in the plasma. The binding of phycoerytherin-labeled anti-alpha4 mAb to blood T cells from PS/2-treated mice was reduced, implying that alpha4 sites were already occupied. T cells and eosinophils in BAL fluid from mice treated with PS/2 or MK2 were phenotypically different from controls. Selective decreases of alpha4+ T cells in the BAL fluid after PS/2 or MK2 treatment were coupled with changes in CD8+, CD11a, and CD62L expression. The alpha4-integrin and VCAM-1 may have important roles in the antigen-induced recruitment of T cells and eosinophils during OA-induced airway inflammation. The data suggest that these adhesion molecules may be suitable targets for therapeutic intervention in certain conditions of pulmonary inflammation.

Objective. To investigate the anti-arthritic effect of recombinant human interleukin-1 receptor antagonist protein (IRAP) in two experimental models of arthritis.Methods. Recombinant IRAP was administered daily to mice with type I1 collagen-induced arthritis (CIA) or with antigen-induced arthritis (AIA) provoked by methylated bovine serum albumin (mBSA). Disease incidence and severity were assessed by a clinical index and histologic features. Serum antibody to type I1 collagen, spleen cell proliferation to mBSA, and anti-IRAP antibodies were measured as indices of immune function.Results. IRAP reduced the incidence and delayed the onset of CIA and suppressed the antibody response to type I1 collagen. In contrast, IRAP did not affect the pathogenesis of AIA and had no effect on either humoral or cellular immune responses to mBSA in arthritic mice.Conclusion. These observations suggest that interleukin-1 may play a prominent role in the development of some, but not all, forms of arthritis.Interleukin-1 (IL-1) is present in the synovial fluid of rheumatoid arthritis (RA) patients (1-3). In approximately 40% of joint fluids from patients with RA, osteoarthritis, and miscellaneous connective tis-

We examined the effect of interleukin-1 (IL-1) administration on a mild and transient inflammatory response in the knees of mice injected intraarticularly with methylated bovine serum albumin (mBSA). Injection of mBSA on day 0 into nonsensitized mice caused a weak inflammatory response confined to the infrapatellar fat pads and involved infiltration by mononuclear cells, neutrophils, and eosinophils. The response developed between days 4 and 7 and resolved by day 28. No erosion of cartilage or subchondral bone was seen. In contrast, mBSA-treated mice injected with recombinant human IL-lP subcutaneously in the ipsilateral footpad on days 0-3 developed a severe monarticular arthritis in the antigen-injected knee. Pannus developed, extending over the articular surfaces, and extensive erosion of cartilage and subchondral bone occurred. Multinucleated giant cells, together with fibrin-like material, were observed at sites of active bone erosion and debris, and large numbers of neutrophils were seen in the joint space. These pathologic features represent a new arthritis model in which IL-1 profoundly augments a weak inflammatory response and induces acute erosive joint

Vinylidenebisphosphonic acid tetraethyl ester (1) and diazo ketones 7a-1 in ether at 22 degrees C yield pyrazoline bisphosphonate tetraethyl esters 8a-1 in moderate to good yield. These compounds were evaluated in animal models of arthritis: rat adjuvant-induced polyarthritis (AIP) and murine antigen-induced arthritis (AIA) and a murine model of chronic inflammation, the delayed type hypersensitivity granuloma reaction (DTH-GRA). (5-Benzoyl-2,4-dihydro-3H-pyrazol-3-ylidene)-bisphosphonic acid tetraethyl ester (8a), and [5-(3-fluorobenzoyl)-2,4-dihydro-3H-pyraxol-3-ylidene]- bisphosphonic acid tetraethyl ester (8d) significantly inhibited the arthritis models, AIP (15 mg/kg) and AIA (25 mg/kg), as well as the DTH-GRA (25 mg/kg). Conversion of 8a to the corresponding bisphosphonic acid, 10a, resulted in loss of activity. Compounds with alkyl substituents on the pyrazoline nitrogen, 9a-d, were inactive in the DTH-GRA. These results show that 8a and 8d have novel antiinflammatory activity and are capable of inhibiting chronic arthritis and inflammation in animals. Such compounds might be useful in man for treating chronic tissue injury associated with arthropathies such as inflammatory joint disease as well as other chronic inflammatory diseases.

Leukocyte rolling and emigration in response to inflammatory stimuli appears to involve both E-selectin- and P-selectin-dependent adhesion, which suggests that these molecules have overlapping functions. To clarify their relative contributions in chronic inflammation, we examined delayed-type contact hypersensitivity (DTH) responses in P-selectin, E-selectin, and E-/P-selectin-deficient mice. Oxazolone-induced increases in ear thickness and ear weight were equivalent in wild-type mice and in P-selectin and E-selectin mutants, but were significantly reduced in E-/P-selectin mutants. The number and area of microabscesses on the ears of E-/P-deficient mice were decreased by 72% and 93%, and the number of leukocytes invading the subdermal ear tissue was reduced. T cells from E-/P-deficient mice transferred oxazolone reactivity into naive wild-type mice. However, when donor T cells from wild-type mice were transferred into E-/P-selectin-deficient mice, the DTH response was significantly impaired. These results show that leukocyte recruitment into a subacute inflammatory reaction can occur when either P-selectin or E-selectin is present, but is significantly reduced when both selectins are absent. Both P- and E-selectin are likely to play important roles in the development and maintenance of inflammatory diseases.