Enhanced Fcγ receptor I, α Mβ 2 integrin receptor expression by monocytes and neutrophils in rheumatoid arthritis: Interaction with platelets
ABSTRACT To investigate platelet and leukocyte activation and interaction in patients with rheumatoid arthritis (RA) and the effect of methotrexate (MTX) or anti-tumor necrosis factor-a (TNF-a) treatment on these variables.
Four-color flow cytometry analysis was performed for quantitative measurement of platelet (P-selectin, PAC-1) and leukocyte (CD11b, CD64) activation markers and estimation of percentage of leukocyte-platelet complexes in whole blood in 20 patients with RA before and after 6 weeks of therapy and in 20 controls. In addition, measures of soluble P-selectin (sP-selectin), beta-thromboglobulin, fibrinogen, prothrombin fragment 1+2, D-dimer, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), interleukin 6 (IL-6), and TNF-a and tender and swollen joint counts were carried out.
Before therapy, PAC-1 binding, expression of CD11b and CD64 on monocytes and neutrophils, circulating levels of monocyte (CD11b+ or CD64+)-platelet complexes, monocyte-PAC-1+ platelet complexes, CRP, ESR, IL-6, TNF-a, fibrinogen, D-dimer and sP-selectin were significantly higher in RA patients compared to controls. The anti-TNF-a therapy significantly reduced levels of monocyte-PAC-1+ platelet complexes, sP-selectin, CRP, ESR, IL-6, TNF-a, fibrinogen, and D-dimer and tender and swollen joint counts. CD64 expression on monocytes was significantly decreased by MTX therapy. PAC-1 binding was not inhibited by MTX or anti-TNF-a.
Increased platelet and leukocyte activation and increased formation of leukocyte-platelet complexes in patients with RA suggest a status of simultaneous activation of the immune and hemostatic systems.
- SourceAvailable from: Luann Phillips
[Show abstract] [Hide abstract]
- "One hypothesis is that a drug interaction could be caused by modulated activity between the monoclonal antibody and Fcγ receptors on effector cells or by the simultaneous effect of the small molecule drug on Fcγ receptor expression . For example, the downregulation of FcγRI on monocytes induced by methotrexate has been reported in patients with rheumatoid arthritis [21, 24]; such activity could potentially affect the action of a concomitantly administered monoclonal antibody. Another hypothesis is that a monoclonal antibody could affect the metabolism of a concomitantly administered small molecule drug via cytokine-induced CYP3A4 inhibition [22, 23]. "
ABSTRACT: Bendamustine plus rituximab has been reported to be effective in treating lymphoid malignancies. This analysis investigated the potential for drug-drug interactions between the drugs in patients with indolent non-Hodgkin lymphoma or mantle cell lymphoma. Data were derived from a bendamustine-rituximab combination therapy study, a bendamustine monotherapy study, and published literature on rituximab monotherapy and combination therapy. Analysis of the potential for rituximab to affect bendamustine systemic exposure included comparing bendamustine concentration-time profile following monotherapy to that following combination therapy and comparing model-predicted Bayesian bendamustine clearance in the presence and absence of rituximab. Analysis of the potential for bendamustine to affect rituximab systemic exposure included plotting observed minimum, median, and maximum serum rituximab concentrations at the end of rituximab infusion (EOI) and 24 h and 7 days post-infusion in patients receiving combination therapy versus concentrations reported in literature following rituximab monotherapy. The established population pharmacokinetic model following bendamustine monotherapy was evaluated to determine its applicability to combination therapy for the purpose of confirming lack of pharmacokinetic interaction. The model adequately described the bendamustine concentration-time profile following monotherapy and combination therapy in adults. There was no statistically significant difference in estimated bendamustine clearance either alone or in combination. Also, rituximab concentrations from EOI to 24 h and 7 days demonstrated a pattern of decline similar to that seen in rituximab studies without bendamustine, suggesting that bendamustine does not affect the rituximab clearance rate. Neither bendamustine nor rituximab appears to affect systemic exposure of the other drug when coadministered.Cancer Chemotherapy and Pharmacology 03/2014; 73(6). DOI:10.1007/s00280-014-2445-5 · 2.77 Impact Factor
[Show abstract] [Hide abstract]
- "Thus, MP measurements do not take these MPs sequestered in cell aggregates into account, which leads to an underestimation of their amount [3,42]. These aggregates were found in higher levels in SLE and RA patients than in controls, but no association with disease activity has been reported to date [3,25,43]. Finally, the decreased level of MPs in active disease could be explained by the destruction of circulating MPs in the peripheral blood by phospholipases, especially sPLA2, which targets its aminophospholipid substrates in shedded membrane particles to generate lysophosphatidic acid . "
ABSTRACT: Cell stimulation leads to the shedding of phosphatidylserine (PS)-rich microparticles (MPs). Because autoimmune diseases (AIDs) are characterized by cell activation, we investigated level of circulating MPs as a possible biomarker in primary Sjögren's syndrome (pSS), systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). We measured plasma levels of total, platelet and leukocyte MPs by prothrombinase capture assay and flow cytometry in 43 patients with pSS, 20 with SLE and 24 with RA and in 44 healthy controls (HCs). Secretory phospholipase A2 (sPLA2) activity was assessed by fluorometry. Soluble CD40 ligand (sCD40L) and soluble P-selectin (sCD62P), reflecting platelet activation, were measured by ELISA. Patients with pSS showed increased plasma level of total MPs (mean +/- SEM 8.49 +/- 1.14 nM PS equivalent (Eq), P < 0.0001), as did patients with RA (7.23 +/- 1.05 n PS Eq, P = 0.004) and SLE (7.3 +/- 1.25 nM PS Eq, P = 0.0004), as compared with HCs (4.13 +/- 0.2 nM PS Eq). Patients with AIDs all showed increased level of platelet MPs (P < 0.0001), but only those with pSS showed increased level of leukocyte MPs (P < 0.0001). Results by capture assay and flow cytometry were correlated. In patients with high disease activity according to extra-glandular complications (pSS), DAS28 (RA) or SLEDAI (SLE) compared with low-activity patients, the MP level was only slightly increased in comparison with those having a low disease activity. Platelet MP level was inversely correlated with anti-DNA antibody level in SLE (r = -0.65; P = 0.003) and serum beta2 microglobulin level in pSS (r = -0.37; P < 0.03). The levels of total and platelet MPs were inversely correlated with sPLA2 activity (r = -0.37, P = 0.0007; r = -0.36, P = 0.002, respectively). sCD40L and sCD62P concentrations were significantly higher in pSS than in HC (P < or = 0.006). Plasma MP level is elevated in pSS, as well as in SLE and RA, and could be used as a biomarker reflecting systemic cell activation. Level of leukocyte-derived MPs is increased in pSS only. The MP level is low in case of more severe AID, probably because of high secretory phospholipase A2 (sPLA2) activity, which leads to consumption of MPs. Increase of platelet-derived MPs, sCD40L and sCD62P, highlights platelet activation in pSS.Arthritis research & therapy 10/2009; 11(5):R156. DOI:10.1186/ar2833 · 3.75 Impact Factor
[Show abstract] [Hide abstract]
- "Extensive investigations have shown that activating FcγRs are of crucial importance for the development of experimental arthritis, whereas the inhibitory FcγRIIb suppress arthritis       . In RA an increased expression of activating FcγRs on blood monocytes and synovial tissue is seen       as well as a significant synovial FcγRIIb expression . Further, a polymorphism in the FcγRIIIA gene, affecting IgG binding to the receptor, has been linked to RA susceptibility and a functional gene variant of FcγRIIB is associated with severe joint erosions in RA  . "
ABSTRACT: Immune complex (IC) binding to Fc gamma receptors (FcgammaRs) is central for inflammatory reactions seen in autoimmune diseases. Consequently, a therapeutic agent with a possibility to interfere with binding of pathogenic IC to FcgammaRs would be valuable in autoimmune disorders such as rheumatoid arthritis (RA). Here we have explored the therapeutic effect of a recombinant soluble human FcgammaRIIb (sFcgammaRIIb) protein in collagen-induced arthritis (CIA). In vitro studies of the sFcgammaRIIb demonstrated binding to mouse IgG, suggesting that sFcgammaRIIb can absorb pathogenic IgG anti-collagen type II (CII) IC in vivo. Hence, administration of sFcgammaRIIb significantly reduced CIA severity compared to control treated mice. The sFcgammaRIIb treated mice had significantly less IgG anti-CII antibodies in serum and lower mRNA levels of inflammatory cytokines compared to control mice. In conclusion, sFcgammaRIIb treatment ameliorates CIA by reducing IC-stimulated inflammation and joint swelling. This suggests that recombinant sFcgammaRIIb may be useful as therapeutic agent in RA.Clinical Immunology 06/2008; 127(2):225-33. DOI:10.1016/j.clim.2008.02.002 · 3.67 Impact Factor