Showing papers by "Andrew C. Issekutz published in 1996"
TL;DR: It is concluded that, with the assay conditions outlined here, EPO and MPO can be used to quantitate the tissue infiltration of eosinophils and neutrophils in the rat even in mixed inflammatory reactions.
145 citations
TL;DR: Rat blood neutrophils express functional VLA-4 that can mediate neutrophil migration to both inflamed joints and dermal inflammatory sites and appears to be able to substitute for LFA-1 in this migration and is particularly important for accumulation in inflamed Joints.
Abstract: Blood neutrophils contribute to joint injury in human and experimental models of arthritis. Neutrophil migration out of the blood in joint inflammation involves both the CD18 (beta2) integrins and a CD18 integrin-independent pathway. To investigate this migration, radiolabeled rat blood neutrophils were used to measure neutrophil accumulation in the inflamed joints of rats with adjuvant arthritis and the role of leukocyte integrins in migration to these joints and to dermal inflammation was determined. Neutrophils migrated rapidly (<2 h) to the inflamed joints 14-18 d after immunization with adjuvant. Blocking monoclonal antibodies (mAbs) to both LFA-1 and Mac-1 together, as well as a mAb to CD18, inhibited neutrophil accumulation in the inflamed joints by 50-75%. However, migration to dermal inflammation induced by C5a(des Arg)' tumor necrosis factor alpha, lipopolysaccharide, and poly-inosine:cytosine was inhibited by approximately 90%. Flow cytometry revealed the expression of low levels of very late antigen 4 (VLA-4) on nearly all rat blood neutrophils. Treatment with anti-VLA-4 plus anti-LFA-1 but neither mAb alone, strongly (60-75%) inhibited neutrophil accumulation in arthritic joints. This mAb combination also inhibited neutrophil migration to dermal inflammatory reactions by 30-70%. Blocking VLA-4 together with the CD18 integrins inhibited neutrophil accumulation by 95-99%, virtually abolishing neutrophil accumulation in cutaneous inflammation. A similar blockade of VLA-4 and CD18 decreased neutrophil accumulation in the inflamed joints by 70-83%, but a significant portion of the neutrophil accumulation to these joints still remained. In conclusion, rat blood neutrophils express functional VLA-4 that can mediate neutrophil migration to both inflamed joints and dermal inflammatory sites. VLA-4 appears to be able to substitute for LFA-1 in this migration and is particularly important for accumulation in inflamed joints. However, there exists an additional CD18- and VLA-4-independent pathway of neutrophil migration to arthritic joints that is not involved in acute dermal inflammation.
135 citations
TL;DR: It is demonstrated that blocking mAb to α4 andβ2 integrins can reduce the severity of adjuvant arthritis, even after joint inflammation has developed; that this treatment can markedly inhibit PMNL and T‐lymphocyte migration to the joints; and that yet to be defined mechanisms distinct from α4 (CD49d) and β2 (CD11/CD18) Integrins, also contribute to leucocytes migration to inflamed joints.
Abstract: The migration of leucocytes from blood into the joint is a key feature of human and experimental arthritis. Adhesion molecules on leucocytes and vascular endothelium are important in this process and may be therapeutic targets for intervention in arthritis. We investigated whether monoclonal antibody treatment to block the alpha 4 integrin, very late activation antigen-4 (VLA-4), and beta 2 integrins (CD11/CD18) administered to rats during the preclinical (day 5) or clinical phase (day 10+) would modify disease. When treatment was initiated 5 days after induction of disease, development of arthritis was significantly reduced by either anti-alpha 4 (TA-2) or anti-beta 2 (WT.3) monoclonal antibodies (mAb) and the combination of both mAb was even more effective (clinical scores: control 11.4; anti-alpha 4 6.6; anti-beta 2 6.8; anti-alpha 4 + anti-beta 2 3.9). When treatment was delayed until arthritis was apparent (day 10), the anti-alpha 4 + anti-beta 2 mAb combination still significantly diminished the arthritis score on day 14 (control 13; anti-alpha 4 + anti-beta 2 7.9). Treatment with anti-alpha 4 + anti-beta 2 mAb decreased the migration to the joints of blood polymorphonuclear leucocytes (PMNL) by 66-79% and of spleen T lymphocytes by 56-75%, depending on the joint. In contrast, PMNL migration was abolished (> 98%) and T-cell migration markedly (87%) inhibited to dermal inflammatory reactions in the same animals. These findings demonstrate: that blocking mAb to alpha 4 and beta 2 integrins can reduce the severity of adjuvant arthritis, even after joint inflammation has developed; that this treatment can markedly inhibit PMNL and T-lymphocyte migration to the joints; and that yet to be defined mechanisms distinct from alpha 4 (CD49d) and beta 2 (CD11/CD18) integrins, also contribute to leucocyte migration to inflamed joints. Identifying these additional adhesion mechanisms may be required to control joint inflammation further.
82 citations
TL;DR: The results demonstrate the β2 integrin dependent PMNL migration in connective tissue may involve primarily Mac‐1, with little involvement of LFA‐1 or ICAM‐1; however, in inflammatory conditions in which TNF‐α and/or IFN‐γ may be generated, a role for L FA‐1–ICAM‐ 1 may be induced.
Abstract: Recently we reported that polymorphonuclear leucocyte (PMNL) migration in vitro through a barrier of human synovial fibroblasts (HSF) involves both beta 2 (CD18) and beta 1 (CD29) integrins on the PMNL. Here we investigated the role of the beta 2 integrin family members, lymphocyte function-associated (LFA)-1 (alpha L beta 2 or CD11a/CD18) and Mac-1 ( alpha M beta 2 or CD11b/CD18), in PMNL migration through HSF and human dermal fibroblast (HDF) monolayers. Treatment of PMNL with monoclonal antibody (mAb) to LFA-1 (anti-alpha L) did not inhibit PMNL migration through either monolayer in response to C5a. In contrast, mAb to Mac-1 (Cd11b) inhibited (by 30-40%) PMNL migration, and by virtually the same extent as mAb to the beta 1 integrin chain (CD18) (40% inhibition). Addition of mAb to LFA-1 to mAb to Mac-1 did not result in greater inhibition. This was in contrast to PMNL migration through human umbilical vein endothelium (HUVE) monolayers, where mAb to LFA-1 or to Mac-1 each partially inhibited PMNL transendothelial migration, and when these mAbs were combined, synergistic inhibition of migration was observed, reaching 90-95% inhibition. Intercellular adhesion molecule 1 (ICAM-1) was not required for Mac-1 mediated migration through HSF or HDF, because treatment of the fibroblasts with mAb R6.5 (F(ab)2) to ICAM-1, which blocks the Mac-1 binding site on ICAM-1, did not inhibit PMNL migration. An LFA-1-ICAM-1 mechanism of PMNL migration through HSF and HDF monolayers could be detected after treatment (4 hr) of the monolayers with TNF-alpha plus IFN-gamma, which upregulated ICAM-1 on the fibroblasts. The results demonstrate the beta 2 integrin dependent PMNL migration in connective tissue may involve primarily Mac-1, with little involvement of LFA-1 or ICAM-1, a situation in marked contrast to PMNL migration across endothelium. However, in inflammatory conditions in which TNF-alpha and/or IFN-gamma may be generated, a role for LFA-1-ICAM-1 may be induced.
41 citations
TL;DR: The results suggest that VCAM‐1 expression by dermal fibroblasts is inducible at the mRNA, protein and functional levels by proinflammatory cytokines.
Abstract: In chronic inflammatory conditions, mononuclear cells infiltrate the involved connective tissue and may persist, perhaps because of binding to adhesion molecules on connective tissue cells, as well as extracellular matrix. Here we investigated whether vascular cell adhesion molecule-1 (VCAM-1) may be induced on human dermal fibroblasts by proinflammatory cytokines. Expression of VCAM-1 was determined by Northern blotting, cell enzyme-linked immunosorbent assay (ELISA) and flow cytometry. Only trace amounts of VCAM-1 mRNA or protein were constitutively expressed on dermal fibroblasts but both were rapidly (within 4 hr) upregulated by tumour necrosis factor-alpha (TNF-alpha) and interleukin-1 alpha (IL-1 alpha) and somewhat slower (20 hr) by interferon-gamma (IFN-gamma). The combination of TNF-alpha and IFN-gamma had at least an additive effect. The adhesion function of the expressed VCAM-1 was examined by studying the adhesion of the Jurkat T lymphocytes to fibroblasts. Adhesion of Jurkat cells to dermal fibroblasts was markedly increased by stimulation of fibroblasts with TNF-alpha and IFN-gamma (22% of cells adhered versus 9% on unstimulated fibroblasts). The increased adhesion was inhibited to that on unstimulated fibroblasts by monoclonal antibody (mAb) to domain 1 of VCAM-1, but not by mAb to domain 4. MAb to very late antigen-4 (VLA-4), the integrin counter-receptor on lymphocytes for VCAM-1, completely inhibited the increase in Jurkat cell adhesion to activated fibroblasts and partly also inhibited basal adhesion to unstimulated fibroblasts. These results suggest that VCAM-1 expression by dermal fibroblasts is inducible at the mRNA, protein and functional levels by proinflammatory cytokines. The VLA-4/VCAM-1 pathway maybe involved in adhesive interactions between T lymphocytes and activated fibroblasts in the skin during chronic dermal inflammatory conditions.
35 citations