Design, Synthesis, and Antiviral Activity of 2‘-Deoxy-2‘-fluoro-2‘-C-methylcytidine, a Potent Inhibitor of Hepatitis C Virus Replication

The pyrimidine nucleoside beta-d-2'-deoxy-2'-fluoro-2'-C-methylcytidine (1) was designed as a hepatitis C virus RNA-dependent RNA polymerase (HCV RdRp) inhibitor. The title compound was obtained by a DAST fluorination of N(4)-benzoyl-1-(2-methyl-3,5-di-O-benzoyl-beta-d-arabinofuranosyl]cytosine to provide N(4)-benzoyl-1-[2-fluoro-2-methyl-3,5-di-O-benzoyl-beta-d-ribofuranosyl]cytosine. The protected 2'-C-methylcytidine was obtained as a byproduct from the DAST fluorination and allowed for the preparation of two biologically active compounds from a common precursor. Compound 1 and 2'-C-methylcytidine were assayed in a subgenomic HCV replicon assay system and found to be potent and selective inhibitors of HCV replication. Compound 1 shows increased inhibitory activity in the HCV replicon assay compared to 2'-C-methylcytidine and low cellular toxicity.

Non-invasive imaging in the diagnosis and management of Takayasu's arteritis

OBJECTIVES

Takayasu's arteritis (TA) is a rare disease, in which early diagnosis and assessment of treatment efficacy remain a problem. Signs and symptoms may be non-specific and conventional blood tests unreliable, with vascular inflammation often persisting in the face of a normal acute phase response. The current "gold standard" investigation, x ray angiography, is invasive and only identifies late, structural changes in vessels. Recently, non-invasive imaging methods have shown promise in the assessment of patients with TA.

METHODS

The invasive and non-invasive imaging performed on all patients in the rheumatology department at the Hammersmith Hospital between May 1996 and May 2002 who fulfilled the ACR criteria for TA were reviewed. All patients were clinically active at diagnosis and were treated with high dose oral prednisolone and additional oral or intravenous immunosuppression.

RESULTS

Non-invasive imaging methods ([(18)F]fluorodeoxyglucose positron emission tomography ([(18)F]FDG-PET) and magnetic resonance imaging (MRI)) provided important additional information about disease activity ([(18)F]FDG-PET) and progression of vessel wall thickening (MRI) when compared with x ray angiography.

CONCLUSIONS

Non-invasive imaging methods provide useful additional information towards the diagnosis and management of TA. Such techniques may allow earlier diagnosis and more accurate assessment of response to treatment than conventional clinical assessment and/or angiography. Non-invasive imaging is likely to be useful in the management of other large vessel vasculitides.

Expression of Fc and complement receptors on peripheral blood monocytes in systemic lupus erythematosus and rheumatoid arthritis

OBJECTIVES

Fcagamma and complement receptors play an important role in the interaction between immune complexes (IC) and monocytes/macrophages. Recent work has demonstrated that their relative expression on these cells may be modified by cytokines, including TNF-alpha and IL-4. Furthermore, cytokines may alter the expression of adhesion molecules such as ICAM-1. However, little data exist on the in vivo expression of specific Fcgamma and complement receptors in systemic lupus erythematosus (SLE) or rheumatoid arthritis (RA), two diseases in which IC are important in pathogenesis.

METHODS

Venous blood was obtained from 30 patients with SLE, 25 with RA and 25 healthy controls. Monocyte phenotype was determined by flow cytometric analysis of whole blood samples, with selective gating using forward and side scatter signals. Surface expression of Fcgamma receptors RI (CD64), RII (CD32) and RIII (CD16), complement receptors CR1 (CD35) and CR3 (CD11b/CD18), and adhesion molecules ICAM-1 (CD54) and CD11a (LFA-1) was determined. The effects of disease activity and corticosteroid therapy on the expression of these molecules were also examined.

RESULTS

The expression of FcgammaRII was reduced on monocytes from patients with SLE compared with healthy controls and patients with RA (P = 0.002). This did not correlate with disease activity using conventional indices [SLEDAI (SLE disease activity index), C3/C4 levels and anti-double-stranded DNA antibody titres], and was independent of prednisolone therapy. There was no significant difference in FcgammaRI or RIII expression on SLE monocytes compared with healthy controls. In contrast, the expression of FcgammaRIII was increased on RA monocytes (P = 0.01), this being highest in patients with active disease. The proportion of FcgammaRIII-positive monocytes was also increased in RA, and prednisolone therapy was associated with a lower proportion of FcgammaRIII-positive cells. An increase in CR3 expression was seen on RA monocytes (P = 0.002), whilst CR1 was increased on monocytes from patients with active SLE or active RA. ICAM-1 expression was reduced on monocytes from patients with SLE (P = 0.002), although high-dose prednisolone therapy was associated with the lowest level of surface ICAM-1 on monocytes.

CONCLUSIONS

Peripheral blood monocytes from patients with SLE or RA display significantly altered phenotypes compared with those from healthy controls. The observed reduction in SLE of FcgammaRII may represent a mechanism by which monocytes are protected from IC-mediated activation. Prednisolone therapy and disease activity had little effect on phagocytic receptor expression. The observed changes may reflect the different cytokine profiles seen in SLE and RA.

Hemoglobin Scavenger Receptor CD163 Mediates Interleukin-10 Release and Heme Oxygenase-1 Synthesis

The recently described hemoglobin scavenger receptor CD163 mediates the endocytosis of hemoglobin:haptoglobin (Hb:Hp) complexes and thereby counters Hb-induced oxidative tissue damage after hemolysis. Although CD163 has been indirectly associated with antiinflammatory and atheroprotective activity, no ligand-receptor-effector pathway has yet been described for this receptor. To understand the significance of CD163 and more clearly define downstream pathways linked to inflammatory resolution, we studied the expression and function of CD163 in human monocytes/macrophages using both in vitro and in vivo models. Differentiation of human blood monocytes into macrophages either by in vitro culture or in resolving cantharidin-induced skin blisters led to an equivalent increase (>15x) in CD163 expression. Elevated CD163 levels were also noted on circulating monocytes in cardiac surgical patients during the resolution phase of the systemic inflammatory response to cardiopulmonary bypass surgery. In each case, binding of Hb:Hp to CD163-bearing cells elicited potent interleukin-10 secretion, and this was inhibited by the anti-CD163 antibody RM3/1. Release of interleukin-10, in turn, induced heme oxygenase-1 stress protein synthesis via an autocrine mechanism. Such induction of heme oxygenase-1 was observed in vivo 24 to 48 hours after the onset of cardiopulmonary bypass surgery. These results identify novel antiinflammatory and cytoprotective effector pathways in human monocytes/macrophages related to Hb scavenging and metabolism, which may have relevance in atheroprotection, wound healing, and patient recovery postoperatively.

An unusual abdominal mass in a renal transplant recipient

Renal transplant recipients are at increased risk of malignancy and infection. We present the case of a 72-year-old-man with recurrent bladder carcinoma, abdominal aortic aneurysm repair, and end-stage renal failure due to renovascular disease. He received a cadaveric renal allograft into his left iliac fossa, was given cyclosporin A, azathioprine, and prednisolone triple therapy immunosuppression, and had no rejection episodes. He presented four years post-transplantation with a two-year history of intermittent sweats and fevers. Previous episodes had been investigated with no firm diagnosis made. This time he had right iliac fossa pain of three weeks' duration. Examination revealed a tender mass. Investigations showed unchanged graft function, but elevated inflammatory indices. Ultrasonography and computed tomography detailed an infiltrating mass associated with the sigmoid colon, which colonoscopy failed to visualise. At laparotomy a 6-cm tumor was removed, with adherent sigmoid colon and bladder dome. Macroscopically the mass was an abscess, and microscopy found acute and chronic inflammatory giant cells and fibrillary masses suggestive of actinomycosis, with no malignancy. The patient recovered uneventfully on antibiotics. At six months' follow-up, examination, inflammatory markers, and radiographic imaging showed no evidence of recurrence. Twelve months later the patient died of rupture of his proximal abdominal aorta. There was no evidence of recurrence at postmortem examination. We conclude with a brief review of actinomycosis in transplant recipients.

Binding constant determination of drugs toward subdomain IIIA of human serum albumin by near-infrared dye-displacement capillary electrophoresis

Drug binding to serum albumin influences several important pharmacological properties such as toxicity, solubility, activity, distribution, and excretion. It is therefore of interest to have methodologies that allow for the determination of drug-albumin affinity constants while simultaneously providing information on the location of the drug binding site. In the present work we describe a method for the determination of binding constants of drugs known to bind to subdomain IIIA of serum albumin. Drugs used in the study were ketoprofen, ibuprofen, quinidine, naproxen, imipramine, and clofibrate. Binding constants of the drugs were determined by near-infrared dye-displacement capillary electrophoresis. The dye-displacement technique uses a competitive-type interaction between the drug of interest and a dye probe to arrive at a binding constant. A heptamethine cyanine dye was used as a probe for drug binding at subdomain IIIA of serum albumin. The utility of the dye as a noncovalent label for serum albumin was investigated. Additionally, the ability of the method to illustrate enantioselective binding is shown. The dye displacement technique has advantages over current electrophoresis-based techniques in that it is faster and uses less reagent.

Aggressive endoscopic resection of inverted papilloma: an update

OBJECTIVE

Endoscopic resection has been proposed for sinonasal inverted papilloma (IP). Our objective was to determine the efficacy of aggressive endoscopic resection of IP.

METHODS

Retrospective analysis was performed on patients undergoing endoscopic resection of IP at the University of Virginia between 1990 and 1996. Total ethmoidectomies, wide maxillary antrostomies, frontal recess explorations, sphenoidotomies, and turbinate resection were performed as required. Once all visible papilloma was removed, residual mucosa was removed by using a diamond burr to polish bone at the site of origin.

RESULTS

Twenty-one patients were treated with endoscopic resection of IP. Only 1 of 21 patients had an adjunctive external procedure (an osteoplastic flap without obliteration). Average follow-up was 41.9 months after initial aggressive endoscopic resection at the ureterovesical angle. Recurrences occurred in 19% (4/21) of patients. One of the 4 had two recurrences. Recurrences occurred in 16 months or less, except for one noted at 35 months and another at 56 months.

CONCLUSIONS

Aggressive endoscopic resection of IP by experienced rhinologists is an acceptable treatment.

Use of non-covalent labeling in illustrating ligand binding to human serum albumin via affinity capillary electrophoresis with near-infrared laser induced fluorescence detection

This paper demonstrates the use of a near-infrared (NIR) dye as a non-covalent label for human serum albumin (HSA). The dye is a water soluble, heptamethine cyanine dye. The utility of the dye as a tracer illustrating the binding of various drugs to HSA is demonstrated via affinity capillary electrophoresis with near-infrared laser-induced fluorescence detection (ACE-NIR-LIF). Additionally, the factors affecting the separation of relevant species were investigated. The change in quantum yield of the dye upon complexation with HSA was calculated. Spectrophotometric measurements were conducted to study the stoichiometry of the dye albumin complex.

Induction of endothelial cell decay-accelerating factor by vascular endothelial growth factor: a mechanism for cytoprotection against complement-mediated injury during inflammatory angiogenesis

OBJECTIVE

Decay-accelerating factor (DAF) is a widely expressed, multifunctional cell surface protein involved in complement regulation and cell signaling. Previous studies have demonstrated that endothelial cell (EC) DAF is up-regulated by tumor necrosis factor alpha and inhibits complement binding. Because vascular endothelial growth factor (VEGF) is cytoprotective to endothelium and is expressed at sites of chronic inflammation, we hypothesized that VEGF may induce DAF expression during inflammatory angiogenesis.

METHODS

Human umbilical vein and dermal microvascular EC were isolated using routine procedures, and the regulation and function of DAF, as well as other complement-regulatory proteins (membrane cofactor protein and CD59), were analyzed following stimulation with VEGF.

RESULTS

Incubation of large- or small-vessel EC with VEGF led to increased expression of DAF, with maximal expression after 48-72 hours of stimulation. This effect depended on the activation of protein kinase C (PKC) and required increased steady-state messenger RNA levels and de novo protein synthesis. Although VEGF-induced EC proliferation was inhibited by both p38 and p42/44 mitogen-activated protein kinase (MAPK) antagonists, DAF up-regulation in response to VEGF was only sensitive to inhibition of p38 MAPK. VEGF-stimulated EC showed a 60% reduction in C3 deposition following complement activation, and this resulted in a marked reduction in complement-mediated EC lysis. These protective effects were abolished by anti-DAF monoclonal antibody 1H4.

CONCLUSION

This study confirms the importance of PKC for the regulation of DAF expression by EC and reveals VEGF to be a physiologic agonist for this pathway. The up-regulation of DAF expression by VEGF may represent an important mechanism for the protection of EC from complement-mediated injury during angiogenesis in inflammatory rheumatic diseases.

Hearing results after primary cartilage tympanoplasty

OBJECTIVES/HYPOTHESIS

Cartilage-perichondrium grafting of the tympanic membrane has been used in an effort to reduce recurrence or progression of middle ear disease. The rigidity of cartilage has obvious benefit in preventing tympanic membrane retraction, but concern has been raised regarding its sound conduction properties Few studies in the literature address hearing results after cartilage tympanoplasty. The purpose of this study was to investigate the hearing results after primary cartilage tympanoplasty and compare them with results after primary tympanoplasty with temporalis fascia.

STUDY DESIGN

A retrospective review of all ear surgeries using cartilage between 1994 and 1999 was performed.

METHODS

Only primary cases in which the ossicular chain was intact and no mastoid surgery was performed were included. Indications for surgery included tympanic membrane perforation, retraction, and cholesteatoma Pre- and postoperative speech reception thresholds and air-bone gaps at 500 Hz, 1,000 Hz, 2,000 Hz, and 4,000 Hz were compared.

RESULTS

Eleven patients comprised the cartilage study group, and there were 11 age- and temporally matched control subjects. The mean improvement in speech reception threshold for both the study group and the control group was 10 dB. The majority of patients in both groups had ABG closure to within 10 dB at all frequencies examined. There were no statistically significant differences in speech reception threshold improvement or air-bone gap closures between the two groups.

CONCLUSIONS

These results demonstrate that hearing results after cartilage tympanoplasty are comparable to those after temporalis fascia tympanoplasty. Therefore, when indicated, a cartilage-perichondrium graft can be used for prevention of disease recurrence or progression without fear of impairing hearing.

Induction of decay-accelerating factor by thrombin through a protease-activated receptor 1 and protein kinase C-dependent pathway protects vascular endothelial cells from complement-mediated injury

There is increasing evidence for functional crosstalk between inflammatory and thrombotic pathways in inflammatory vascular diseases such as atherosclerosis and vasculitis. Thus, complement activation on the endothelial cell (EC) surface during inflammation may generate thrombin via the synthesis of tissue factor. We explored the hypothesis that thrombin induces EC expression of the complement-regulatory proteins decay-accelerating factor (DAF), membrane cofactor protein (MCP), and CD59 and that this maintains vascular integrity during coagulation associated with complement activation. Thrombin increased DAF expression on the surface of ECs by 4-fold in a dose- and time-dependent manner as measured by flow cytometry. DAF up-regulation was first detectable at 6 hours and maximal 24 hours poststimulation, whereas no up-regulation of CD59 or MCP was seen. Thrombin-induced expression required increased DAF messenger RNA and de novo protein synthesis. The response depended on activation of protease-activated receptor 1 (PAR1) and was inhibited by pharmacologic antagonists of protein kinase C (PKC), p38 and p42/44 mitogen-activated protein kinase, and nuclear factor-kappa B. The increased DAF expression was functionally relevant because it significantly reduced C3 deposition and complement-mediated EC lysis. Thus, thrombin-generated at inflammatory sites in response to complement activation-is a physiologic agonist for the PKC-dependent pathway of DAF regulation, thereby providing a negative feedback loop protecting against thrombosis in inflammation. (Blood. 2000;96:2784-2792)

Resting and activated T cells induce expression of E-selectin and VCAM-1 by vascular endothelial cells through a contact-dependent but CD40 ligand-independent mechanism

This study explored the effect on endothelial cell (EC) activation of contact with T lymphocytes, which occurs during lymphocyte emigration into inflamed tissues. Addition of T cells to umbilical vein or dermal microvascular EC monolayers stimulated expression of EC E-selectin and VCAM-1. This response required direct cell:cell contact, but not T-cell activation. The capacity of resting CD4+ T cells to activate EC was restricted to the CD45RO+ subset and could be enhanced by 6 h prestimulation of T cells with PMA and ionomycin. The EC-stimulating capacity of resting or activated T cells was independent of CD40 ligand. Furthermore, inhibition of TNF-alpha/beta and IL-1alpha/beta, together with CD40 ligand, failed to inhibit EC activation by resting T cells and only inhibited the response to PMA- and ionomycin-activated T cells by 40 +/- 18%. Our data suggest that T-cell-EC interactions can lead to EC activation through a novel contact-dependent, but CD40 ligand-independent, mechanism.

An anti-inflammatory property of aprotinin detected at the level of leukocyte extravasation

BACKGROUND

Aprotinin is a serine protease inhibitor used extensively in cardiac operations to reduce postoperative bleeding. It has also been used in trials aimed at reducing the systemic inflammatory response to cardiopulmonary bypass. It remains unclear whether the anti-inflammatory action of aprotinin is related to its general ability to suppress leukocyte activation or whether aprotinin can exercise effects during the leukocyte-endothelial cell adhesion cascade.

METHODS

We used intravital microscopy to study the 3 main stages of the adhesion cascade (leukocyte rolling, firm adhesion, and extravasation) within the mesenteric microcirculation of rats. This in vivo technique allows leukocyte recruitment to be viewed directly through the transparent mesentery of anesthetized animals.

RESULTS

Aprotinin, given by continuous infusion at a clinically relevant dose, exerted no effect on the rolling or firm adhesion responses toward local chemoattractant N -formyl-methyl-leucyl-phenylalanine but significantly inhibited extravasation of leukocytes (73% at 40 minutes, P =.04) into surrounding tissues. In parallel in vitro experiments, aprotinin (used at 200, 800, and 1600 kIU/mL) dose dependently inhibited neutrophil transmigration through cultured endothelial cells in response to 3 different chemoattractants: N -formyl-methyl-leucyl-phenylalanine (P <.001 at 800 and 1600 kIU/mL), interleukin 8 (P <.05 at 200 kIU/mL and P <.001 at 800 and 1600 kIU/mL), and platelet-activating factor (P <.05 at 1600 kIU/mL).

CONCLUSIONS

Our studies have therefore revealed a novel anti-inflammatory mechanism of aprotinin operating at the level of leukocyte extravasation. These findings may be relevant in the prevention of systemic inflammation after cardiopulmonary bypass through the use of protease inhibitors.

Anti-Kaposi's sarcoma and antiangiogenic activities of sulfated dextrins

Delivery of the sulfated polysaccharide dextrin 2-sulfate by the intraperitoneal route to the lymphatic circulation resulted in a clinically significant improvement in Kaposi's sarcoma in three patients. Our in vitro studies show that although sulfated dextrins do not interfere with the growth of isolated human umbilical vein endothelial cells, they do inhibit the morphological differentiation of endothelial cells into tubes as well as reduce new vessel formation in a placental angiogenesis assay. The antiangiogenic effect of dextrin 6-sulfate is greater than that of dextrin 2-sulfate and is independent of their anti-human immunodeficiency virus type 1 activities.

Induction of decay-accelerating factor by cytokines or the membrane-attack complex protects vascular endothelial cells against complement deposition

Vascular endothelium is continuously exposed to complement-mediated challenge, and this is enhanced during inflammation. Although the complement-regulatory proteins decay-accelerating factor (DAF), CD59, and membrane cofactor protein (MCP) protect endothelial cells (ECs) against complement-mediated injury, the control of their expression and relative contributions to vascular protection is unclear. We explored the hypothesis that mechanisms exist which induce upregulation of complement-regulatory proteins on ECs to maintain vascular function in inflammation. Tumor necrosis factor alpha (TNFalpha) and interferon gamma (IFNgamma) each increased DAF expression but not CD59 or MCP expression, and a combination of these cytokines was more potent than either alone. Cytokine-induced expression depended on increased DAF mRNA and de novo protein synthesis and was maximal by 72 hours. In addition, assembly of the membrane-attack complex (MAC) on ECs induced a 3-fold increase in DAF expression, and this was enhanced by cytokines. DAF upregulation was not inhibited by protein kinase C (PKC) antagonists. The increase in DAF was functionally relevant since it reduced complement 3 (C3) deposition by 40%, and this was inhibited by an anti-DAF monoclonal antibody. These observations indicate that upregulation of DAF expression by cytokines or MAC may represent an important feedback mechanism to maintain the integrity of the microvasculature during subacute and chronic inflammatory processes involving complement activation.

Pulmonary granulocyte kinetics in relation to endothelial and granulocyte activation

The aim of the study was to measure the peripheral blood levels of soluble E-selectin in patients with systemic inflammation and compare them with in vivo granulocyte activation, pulmonary intravascular granulocyte pooling, pulmonary extravascular granulocyte migration and 99mTc-diethylenetriaminepenta-acetic acid (DTPA) aerosol clearance, an index of lung injury. The level of soluble E-selectin was measured by capture ELISA. Granulocytes were labelled with 111In and 99mTc for quantification of pulmonary granulocyte kinetics. The pulmonary vascular granulocyte pool (PGP) was expressed as a fraction of the total blood granulocyte pool. Pulmonary granulocyte migration was quantified on 24-h images using the 111In signal. Granulocyte activation was quantified as the percentage of circulating cells showing shape change ('primed'). Lung injury was assessed from the clearance rate of inhaled 99mTc-DTPA aerosol. Eighteen patients with systemic inflammation were studied: five with inflammatory bowel disease, eight with systemic vasculitis, four with graft versus host disease and one with a recent renal transplant. The peripheral blood levels of soluble E-selectin were significantly elevated in patients with systemic inflammation. The level of soluble E-selectin showed a significant association with granulocyte migration (Spearman rank correlation coefficient, Rs=0.53; P<0.05) but not with PGP or with the percentage of cells showing shape change (P>0.05 for both). Granulocyte migration was bimodal: patients were therefore subdivided into 'migrators' and 'non-migrators'. Soluble E-selectin level, 99mTc-DTPA clearance and PGP, but not the percentage of cells showing shape change, were significantly higher in migrators than in non-migrators. We conclude that pulmonary intravascular granulocyte pooling is increased in the presence of increased numbers of circulating primed granulocytes but increased pooling does not by itself promote granulocyte migration into the lung interstitium. Insofar as an elevated level of E-selectin in peripheral blood reflects vascular endothelial activation, the data are consistent with the notion that pulmonary endothelial activation is required, in addition to granulocyte activation and an expanded PGP, for granulocyte migration into lung parenchyma and, therefore, for lung injury to occur.

NSAIDs and the oesophagus

There have been many studies documenting the deleterious effects of non-steroidal anti-inflammatory drugs (NSAIDs) on the gastrointestinal tract, and it is widely accepted that these agents cause mucosal damage in the stomach, duodenum, jejunum, ileum and colon. The mechanism of this toxicity is at least partly due to inhibition of endogenous prostaglandin synthesis. Prostaglandins, especially PGE2, PGI2 and the synthetic PGE1 analogue misoprostol, protect the stomach from these harmful effects. There is good theoretical evidence that the opposite is the case in the oesophagus, with prostaglandins causing relaxation of the lower oesophageal sphincter, increasing acid reflux and acting as mediators of the inflammatory response. NSAIDs have beneficial effects in some models of oesophagitis and have even been proposed as treatment for oesophagitis. In spite of these theoretical benefits, there are many reports implicating NSAIDs in the pathogenesis of oesophagitis, oesophageal ulceration and stricture formation.

Human umbilical vein and dermal microvascular endothelial cells show heterogeneity in response to PKC activation

Changes in endothelial cell (EC) phenotype are central to the function of endothelium in inflammation. Although these events mainly occur in the microvasculature, previous studies have predominantly used large-vessel EC. Using enzyme-linked immunosorbent and flow cytometric assays, we compared the responses of human umbilical vein endothelial cells (HUVEC) and dermal microvascular endothelial cells (DMEC) to the activation of protein kinase C (PKC). Stimulation with phorbol 12,13-dibutyrate and more selective PKC agonists, including 12-deoxyphorbol 13-phenylacetate 20-acetate (dPPA), induced morphological changes and proliferation in both EC types. PKC activation induced a marked increase in Thy-1 expression on DMEC and only a moderate rise on HUVEC. Furthermore, heterogeneity in the induction of the adhesion molecules intercellular adhesion molecule 1, vascular cell adhesion molecule 1 IVCAM-1), and E-selectin between the two EC types following activation of PKC was demonstrated. In particular, E-selectin and VCAM-1 were significantly upregulated on HUVEC but not DMEC. The data indicate that the PKC pathway is unlikely to be important for E-selectin and VCAM-1 expression in the microvasculature but are consistent with a role for PKC in angiogenesis. This diversity in signaling in response to PKC activation may depend on differential utilization of PKC isozymes and may facilitate specialized endothelial responses.

Systemic lupus erythematosus, thrombocytopenia, microangiopathic haemolytic anaemia and anti-CD36 antibodies

Thrombocytopenia in patients with acute systemic lupus erythematosus (SLE) frequently presents the clinician with considerable diagnostic and therapeutic difficulties. In this Grand Round, we present a 48-yr-old woman with a 7 yr history of lupus, who presented with acute proliferative glomerulonephritis and nephrotic syndrome, pneumonia, profound hypocomplementaemia and a severe microangiopathic haemolytic anaemia with associated thrombocytopenia. Her thrombocytopenia proved initially refractory to conventional immunosuppressive therapy, and corticosteroids, and resolved only with plasma exchange and repeated fresh frozen plasma infusions. Serological testing revealed high-titre antinuclear antibodies (ANA) and markedly raised antibodies to double-stranded (ds) DNA, but no significant elevation in anticardiolipin antibodies. Platelet-associated IgG and IgM and antibodies to the CD36 glycoprotein antigen, expressed on platelets and endothelium, were detected in the serum. We address some of the difficult diagnostic and management issues raised by this complex patient and the possible immunopathological links between antibodies to CD36, immune-mediated red cell destruction, thrombocytopenia and thrombotic microangiopathic haemolytic anaemia.