We monitored the number of intravascular platelet-leukocyte aggregates (PLAs) and thrombotic occlusions (TOs) by intravascular microscopy in the mesentery of rats receiving antiphospholipid (aPL) immunoglobulin G (IgG) purified from the sera of patients with antiphospholipid syndrome. aPL IgG had no procoagulant effect, but it caused rapid endothelial deposition of fibrinogen, followed by PLA and TO in rats receiving an intraperitoneal injection of bacterial lipopolysaccharide 3 hours before IgG infusion. Anti-␤2-glycoprotein I-depleted aPL IgG failed to induce PLAs and TOs. C3 and C9 colocalized with aPL IgG on the mesenteric vessels. The number of PLAs and TOs was markedly reduced in C6-deficient rats and in animals treated with anti-C5 miniantibody, suggesting the contribution of the terminal complement (C) complex to the aPL antibody-mediated intravascular thrombosis. In conclusion, our data indicate that antibodies to ␤2-glycoprotein I trigger coagulation subsequent to a priming proinflammatory factor and that the terminal C complex is the main mediator of the coagulation process. (Blood. 2005; 106:2340-2346)

During early pregnancy, uterine mucosa decidualization is accompanied by a drastic enrichment of CD56 high CD16 ؊ natural killer (NK) cells. Decidual NK (dNK) cells differ from peripheral blood NK (pbNK) cells in several ways, but their origin is still unclear. Our results demonstrate that chemokines present in the uterus can support pbNK cell migration through human endothelial and stromal decidual cells. Notably, we observed that pregnant women's pbNK cells are endowed with higher migratory ability compared with nonpregnant women's or male donors' pbNK cells. Moreover, NK cell migration through decidual stromal cells was increased when progesterone-cultured stromal cells were used as substrate, and this correlated with the ability of progesterone to up-regulate stromal cell chemokine expression. Furthermore, we demonstrate that dNK cells migrate through stromal cells using a distinct pattern of chemokines. Finally, we found that pbNK cells acquire a chemokine receptor pattern similar to that of dNK cells when they contact decidual stromal cells. Collectively these results strongly suggest that pbNK cell recruitment to the uterus contributes to the accumulation of NK cells during early pregnancy; that progesterone plays a crucial role in this event; and that pbNK cells undergo reprogramming of their chemokine receptor profile once exposed to uterine microenvironment. IntroductionNatural killer (NK) cells represent a distinct population of circulating and tissue-resident lymphocytes that play an important role in the early phases of immune responses against microbial pathogens by exhibiting cytotoxic functions and secreting a number of cytokines and chemokines. NK cells develop from a lymphoid precursor resident in the bone marrow (BM), considered the main site of NK cell generation, however, the existence of a pathway of NK cell development in the thymus has been recently suggested and evidence also indicates that final maturation of NK cell precursors can occur in the periphery. [1][2][3] During development and activation, NK cells acquire a multiple cell surface receptor system including both activating and inhibitory receptors that finely control their functional activation. 4 Some of these receptors are oligoclonally distributed and/or are expressed at different densities on circulating NK cells. Based on cell surface density of these receptors, phenotypically distinct peripheral blood NK (pbNK) cell populations have been identified and suggested to represent specialized subsets capable of performing different functions and endowed with distinct migratory properties. 5 Mature NK cells circulate mainly in the peripheral blood, but are also present in several lymphoid and nonlymphoid organs such as spleen, lymph nodes, tonsils, liver, lungs, intestine, and uterus. 1,[6][7][8] Interestingly, NK cells are the most abundant class of lymphocytes found in the mucosal tissues of maternal uterus where their number reaches 70% to 80% of the total leukocytes in the first trimester of pregnancy, then start to decline,...

CCR1 and, to a lesser extent, CCR5, the receptors for CCL3 and CCL4, were found in CLL-derived monocyte-macrophages. Consistently, CCL3 increased monocyte migration, and CD68 + macrophage infiltration was particularly high in BMB from CD38 + CD49d + CLL. Conditioned media from CCL3-stimulated macrophages induced endothelial cells to express vascular cell adhesion molecule-1 (VCAM-1), the CD49d ligand, likely through tumor necrosis factor A overproduction. These effects were apparent in BMB from CD38 + CD49d + CLL, where lymphoid infiltrates were characterized by a prominent meshwork of VCAM-1 + stromal/endothelial cells. Lastly, CD49d engagement by VCAM-1 transfectants increased viability of CD38 + CD49d + CLL cells. Altogether, CD38 and CD49d can be thought of as parts of a consecutive chain of events ultimately leading to improved survival of CLL cells. [Cancer Res 2009;69(9):4001-9]

An in vivo model of human CD20+ B-lymphoma was established in severe combined immunodeficiency mice to test the ability of human neutralizing miniantibodies to CD55 and CD59 (MB55 and MB59) to enhance the therapeutic effect of rituximab. The miniantibodies contained single-chain fragment variables and the hinge-CH2-CH3 domains of human IgG 1 . LCL2 cells were selected for the in vivo study among six B-lymphoma cell lines for their high susceptibility to rituximab-dependent complement-mediated killing enhanced by MB55 and MB59. The cells injected i.p. primarily colonized the liver and spleen, leading to the death of the animals within 30 to 40 days. Thirty percent of mice receiving biotin-labeled rituximab (25 Mg) i.p. on days 4 and 11 after cell injection survived to 120 days. Administration of biotin-labeled rituximab, followed by avidin (40 Mg) and biotin-labeled MB55-MB59 (100 Mg) at 4-h intervals after each injection resulted in the survival of 70% of mice. Surprisingly, 40% of mice survived after the sole injection of avidin and biotinlabeled MB55-MB59, an observation consistent with the in vitro data showing that the miniantibodies induced killing of f25% cells through antibody-dependent cell cytotoxicity. In conclusion, MB55 and MB59 targeted to tumor cells represent a valuable tool to enhance the therapeutic effect of rituximab and other complement-fixing antitumor antibodies.

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The kinins are a family of vasoactive peptides including bradykinin, kallidin and methionyl-lysyl-bradykinin, the latter two compounds being converted very rapidly to bradykinin by aminopeptidases. Bradykinin is a low molecular weight (1060.21 Da; C 50 H 73 N 15 O 11 ) nonapeptide, which is rapidly metabolized by endogenous metalloproteases including angiotensin-converting enzyme (ACE or kininase II), neutral endopeptidase (NEP or neprilysin), carboxypeptidase N (CPN or kininase I) and aminopeptidase P (1). Bradykinin has only a short plasma half-life of 15 s, and circulating levels are usually relatively low (0.2-7.1 pM) (2, 3).Much progress was made in understanding the physiological role of kinins with the development of selective antagonists for endothelial B 1 and B 2 receptors (4) and of C1 esterase inhibitor (C1-INH)-and B 2 -receptor-transgenic mice (5, 6). Bradykinin binds these receptors, exerting potent effects in different pathophysiological states (7) (Fig. 1). For example, bradykinin exerts potent antihypertensive, antithrombogenic, antiproliferative and antifibrogenic effects (8) as summarised in Table 1. Bradykinin also participates in inflammatory processes by activating endothelial cells to promote vasodilation and increased vascular permeability, producing classical symptoms of inflammation such as redness, heat, swelling and pain (1, 9). Specifically, bradykinin contributes to tissue hyper-responsiveness and local inflammation in allergic rhinitis, asthma and anaphylaxis, while bradykinin-dependent angioedema can result from hereditary or acquired C1-INH deficiency or the use of ACE inhibitors (ACEi) to treat hypertension, heart failure, diabetes or scleroderma. AbstractBradykinin has been implicated to contribute to allergic inflammation and the pathogenesis of allergic conditions. It binds to endothelial B 1 and B 2 receptors and exerts potent pharmacological and physiological effects, notably, decreased blood pressure, increased vascular permeability and the promotion of classical symptoms of inflammation such as vasodilation, hyperthermia, oedema and pain. Towards potential clinical benefit, bradykinin has also been shown to exert potent antithrombogenic, antiproliferative and antifibrogenic effects. The development of pharmacologically active substances, such as bradykinin receptor blockers, opens up new therapeutic options that require further research into bradykinin. This review presents current understanding surrounding the role of bradykinin in nonallergic angioedema and other conditions seen by allergists and emergency physicians, and its potential role as a therapeutic target.

We have previously shown that C1q is expressed on endothelial cells (ECs) of newly formed decidual tissue. Here we demonstrate that C1q is deposited in wound-healing skin in the absence of C4 and C3 and that C1q mRNA is locally expressed as revealed by real-time PCR and in situ hybridization. C1q was found to induce permeability of the EC monolayer, to stimulate EC proliferation and migration, and to promote tube formation and sprouting of new vessels in a rat aortic ring assay. Using a murine model of wound healing we observed that vessel formation was defective in C1qa −/− mice and was restored to normal after local application of C1q. The mean vessel density of wound-healing tissue and the healed wound area were significantly increased in C1q-treated rats. On the basis of these results we suggest that C1q may represent a valuable therapeutic agent that can be used to treat chronic ulcers or other pathological conditions in which angiogenesis is impaired, such as myocardial ischemia.complement | vasculogenesis | animal models

This study was prompted by the observation that decidual endothelial cells (DECs), unlike endothelial cells (ECs) of blood vessels in normal skin, kidney glomeruli and brain, express surface-bound C1q in physiologic pregnancy. This finding was unexpected, because deposits of C1q are usually observed in pathologic conditions and are associated with complement activation. In the case of DECs, we failed to detect immunoglobulins and C4 co-localized with C1q on the cell surface. Surprisingly, DECs expressed mRNA for the three chains of C1q and secreted detectable level of this component in serum-free medium. The ability to synthesize C1q is acquired by DECs during pregnancy and is not shared by ECs obtained from endometrium and from other sources. Cell-associated C1q has a molecular weight similar to that of secreted C1q and is released from DECs following treatment with heparinase or incubation at low pH. This suggests that C1q binds to DECs and it is not constitutively expressed on the cell surface. C1q is localized at contact sites between endovascular trophoblast and DECs and acts as an intercellular molecular bridge because adhesion of endovascular trophoblast to DECs was inhibited by antibodies to C1q and to a receptor recognizing its globular portion expressed on trophoblast.