Faculty Bibliography

We describe, in rheumatoid arthritis (RA), abnormalities in the expression and distribution of heat shock protein (hsp) and dendritic cells (DCs) that are conducive to cross-priming and DC cross-talk. As detected by ELISA, inducible (i)hsp70 was dramatically increased in RA synovial fluid (RASF) vs normal human and RA sera and osteoarthritis and gout synovial fluid. Immunoblot analysis of fresh RASF cells revealed marked increases in ihsp70 and activation of its transcription factor heat shock factor-1, compared with fresh normal peripheral blood cells. Flow cytometry and microscopy demonstrated high levels of ihsp70 on the surface of RASF myeloid DCs (but not normal myeloid DCs) that occurred concurrently with hspRs (CD91/CD14). ihsp70 present in RASF exhibited chaperoning potential, as indicated by the capture of ihsp70 present in RASF on the surface of normal DCs. Binding was partially competitively inhibited by excess alpha(2)-macroglobulin, indicating that hspRs in addition to CD91 participate in the capture process. These data indicate that ihsp70 may chaperone autologous Ags into immature RASF DCs via hspRs, and that cross-talk between DCs coexpressing hsp/hspRs reflects a disease process in RA. The induction of surface ihsp70 on normal cells after sublethal heat stress and the release of ihsp70 from normal DCs after inflammatory stress also suggest that the pattern of ihsp70 expression in RASF occurs in response to sustained stress.

A 21-year-old woman with a history of systemic lupus erythematosus (SLE) presented to the emergency room with a chief complaint of substernal chest pain and palpitations. She had undergone a four-vessel coronary artery bypass graft operation with separate saphenous vein grafts to the left anterior descending (LAD), obtuse marginal (OM) 1 and 2, and distal right coronary arteries (RCA) 8 months prior to admission. The patient underwent angiography of the coronary vessels, which showed severe diffuse disease with a long, 90% narrowing of the vein graft to the LAD and closed vein grafts to OM1 and OM2. The RCA graft showed mild diffuse disease. An intervention was done in which the LAD was stented twice with subsequent TIMI 3 flow. Advances in medical therapy and a better understanding of the disease have contributed to a dramatic improvement in the long-term survival of patients with SLE. However, despite the overall long-term improvement, coronary artery disease remains a major cause of morbidity and mortality with an incidence of approximately nine-fold greater than would be expected for this population

OBJECTIVE:To investigate the physiology of interleukin 13 (IL-13) in rheumatoid arthritis (RA) and the effects of tumor necrosis factor (TNF) antagonists (etanercept) on the distribution of IL-13 in patients with RA. METHODS:We measured cytokine levels in RA sera (pre/post etanercept), RA synovial fluid (SF), osteoarthritis (OA) SF, and normal human sera by ELISA. Detection of IL-13 was not influenced by rheumatoid factor, as revealed in spike recovery and isotype antibody control studies. Biologically active IL-13 in RA SF was studied using dendritic cell (DC) progenitors that develop into mature DC with IL-13 and with neutralizing antibodies to IL-13. The modulation of IL-13 by etanercept was compared to that of IL-6 and monocyte colony stimulating factor (M-CSF). The effect of etanercept on the ability of RA sera to promote DC growth was studied using DC progenitors. RESULTS:IL-13 was increased in RA sera versus normal sera, OA SF, and RA SF. Relative to OA SF and normal sera, RA SF was enriched in IL-13. The IL-13 contained in RA samples was biologically active, prompting DC growth from progenitors. Circulating DC growth activity was strongly reduced by anti-TNF therapy. Whereas decreases in DC growth factors including IL-13 and IL-6 occurred with etanercept therapy and were associated with clinical improvement, concurrent increases in circulating M-CSF (a non-DC, monocyte-specific growth factor) were noted. CONCLUSION/CONCLUSIONS:The increase of biologically active IL-13 in RA supports the concept that IL-13 regulates immune cell (including dendritic cell) activity and indicates how the varied anatomical distribution of cytokines may play a role in the RA disease process. The differential regulation of circulating IL-13 and M-CSF levels by TNF antagonists further implies discrete roles in the TNF-cytokine network in RA.

Large quantities of fibronectin (Fn) are present in inflammatory synovial fluid. Inflammatory synovial fluid Fn, while indistinguishable from plasma Fn on the basis of reactivity to polyclonal antibodies, displays alterations in molecular size and charge. Since biochemical differences between plasma and synovial fluid fibronectins might be in part due to differences in glycosylation we have compared the carbohydrate composition of plasma Fn, synovial fluid Fn, and Fn from synoviocyte conditioned medium by biochemical assay, glycopeptide analysis, and binding to a series of lectins. Synovial fluid Fn has a greater carbohydrate content but contains less sialic acid when compared with plasma Fn. Glycopeptides formed from synovial fluid Fn are smaller than plasma Fn glycopeptides. These data suggest the presence of an additional N-linked oligosaccharide chain on synovial fluid Fn. In addition, synovial fluid Fn contains N-acetyl galactosamine indicating the presence of O-linked oligosaccharides. Synovial fluid Fn and Fn isolated from rheumatoid synoviocyte-conditioned medium display strong reactivity with the lectins wheat germ agglutinin (WGA) and peanut agglutinin (PNA), whereas normal and rheumatoid plasma Fn react weakly. The PNA reactivity of synovial fluid Fn is mediated by terminal beta-galactose residues on the gelatin-binding domain, whereas the enhanced WGA reactivity of synovial Fn is mediated by a sialic acid containing oligosaccharide located on a 27-kD C-terminal fragment. These data demonstrate domain-specific biochemical differences between plasma and synovial fluid fibronectins. These differences suggest a local origin for synovial fluid Fn and may contribute to functional differences between these forms of the protein.

Plasma fibronectin was measured by ELISA in 25 samples from 22 patients with systemic lupus erythematosus (SLE). The mean fibronectin level for the entire patient group (654 micrograms/ml) was greater than that of normal controls (450 micrograms/ml), with highest levels observed in the subgroup of patients with severe disease activity (838 micrograms/ml) followed by those with moderate disease activity (732 micrograms/ml) (p = .04). Fourteen patients with other rheumatic disease had a mean fibronectin level of 407 micrograms/ml. Decreases in fibronectin levels corresponded to clinical improvement and reductions in DNA binding. Although elevated fibronectin levels did not correspond to any specific pattern of organ system involvement, fibronectin levels seem to parallel disease activity in certain patients. Future longitudinal studies of plasma fibronectin in SLE may further define its role as an indicator of disease activity.