AT-RISK: AuToimmune disorders and cardiovascular RISK

Background

Increased cardiovascular risk has been suggested for selected autoimmune disorders. Yet, for many conditions, evidence is insufficient to design more targeted prevention measures and guide clinical decisions.

Methods

We used linked primary and secondary electronic health records from the Clinical Practice Research Datalink (CPRD) to assemble a cohort of individuals newly diagnosed with any of 19 autoimmune disorders between 01/01/2000 and 31/12/2017 and free of cardiovascular disorders (CVD) up to 12 months after diagnosis, and up to five individuals matched on age, sex and socioeconomic status, with follow-up until 30/06/2019. We investigated incidence of nine cardiovascular outcomes and used cox-proportional hazards models to examine differences in patients with and without autoimmune disorders accounting for known cardiovascular risk factors.

Findings

We identified 432,883 individuals with autoimmune disorders and 2,159,350 matched controls. Of these, 104,504 people with and 450,195 without autoimmune disorders developed incident CVD during a median of 5.3 [interquartile range: 2.6, 9.6] years of follow-up. Patients with one or more autoimmune disorders had higher risk of cardiovascular outcomes: adjusted hazard ratio (HR) [95% confidence interval (CI)] 1.34 [1.31, 1.37]. This relationship held for every individual cardiovascular disorder and increased progressively with the number of autoimmune disorders present. Among autoimmune disorders, those associated with systemic inflammation, such as type I diabetes (2.09 [1.91, 2.28]), systemic sclerosis (2.90 [2.29, 3.67]) and systemic lupus erythematosus (2.21 [1.96, 2.50]) presented with highest overall cardiovascular risk (Figure).

Interpretation

Autoimmune disorders are associated with a high risk of developing cardiovascular outcomes. These findings warrant targeted cardiovascular prevention measures for patients with autoimmune disorders and further research into pathophysiological mechanisms underlying these complications.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie (grant agreement No 843267) and from the European Society of Cardiology (grant number App000037070).

Somatostatin receptor PET/MR imaging of large vessel inflammation in active compared with inactive vasculitis and atherosclerosis

Background

Use of 18F-FDG PET in large vessel vasculitis (LVV) is limited by non-specific uptake due to arterial remodelling and/or atherosclerosis leading to diagnostic uncertainty.

Purpose

To investigate somatostatin receptor 2 (SST2) as a novel inflammation-specific PET imaging target in LVV.

Methods

In a prospective observational cohort study, we tested the ability of PET/MRI using two somatostatin receptor tracers (68Ga-DOTATATE and 18F-FET-βAG-TOCA) to differentiate active from inactive LVV, and aortic atherosclerosis in patients with recent myocardial infarction. Ex vivo mapping of the imaging target was performed using immunofluorescence microscopy, imaging mass cytometry, and bulk, single-cell and single-nuclei RNA sequencing of temporal artery biopsies from LVV patients.

Results

Sixty-one participants were included (LVV, n=27; myocardial infarction ≤2 weeks, n=25; control subjects with an oncological indication for imaging, n=9). LVV patients (mean age 58 [SD 16] years; 78% female; 63% active or grumbling disease) had giant cell arteritis (n=13), Takayasu arteritis (n=13), or unspecified LVV (n=1). Baseline index vessel SST2 PET maximum tissue-to-blood ratio (TBRmax) was 61.8% (95% CI 31.5–99.0%, p<0.0001) higher in patients with active/grumbling LVV than inactive LVV, and 34.6% (95% CI 15.1–57.6%, p=0.0002) higher than recent myocardial infarction (Fig. 1a–c; arrow: PET signal; arrowhead: aortic thickening; asterisk: aortic atherosclerosis), with good diagnostic accuracy (AUC ≥0.86, p<0.001 for both). None of the control subjects without LVV or MI had increased arterial SST2 PET signal (Fig. 1d).

Mean aortic TBRmax was strongly correlated with Indian Takayasu Clinical Activity Score (r=0.82 [95% CI 0.46–0.95], p=0.001) and maximum wall thickness on MRI (r=0.68 [95% CI 0.31–0.87], p=0.002). SST2 PET/MRI was generally consistent with 18F-FDG PET/CT in LVV patients with contemporaneous scans (Fig. 1a, b), but with very low background signal in the brain and heart allowing for unimpeded assessment of nearby coronary, myocardial, and intracranial artery involvement. On follow-up imaging after a mean 9.3 (SD 3.2) months, clinically effective treatment for LVV was associated with a 0.49 ±SEM 0.24 (p=0.04; 22.3%) reduction in SST2 PET TBRmax, with good scan-scan repeatability in inactive LVV patients with no change in treatment (ICC 0.86, 95% CI 0.04–0.99).

SST2 localised to macrophages, pericytes, and perivascular adipocytes in inflamed arterial specimens (Fig. 2; a: H&E; b: imaging mass cytometry; arrow: SST2/CD68 co-staining). SSTR2-expressing macrophages co-expressed pro-inflammatory markers (S100A8, S100A9). Specific SST2 radioligand binding was confirmed by autoradiography in LVV specimens.

Conclusion

This is the first study to examine SST2 PET/MRI in LVV and to provide histological and gene expression data for validation. Here we show this novel approach holds major promise for diagnosis and therapeutic monitoring in LVV.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Wellcome Trust; Imperial NIHR Biomedical Research Centre

Vessel wall magnetic resonance and arterial spin labelling imaging in the management of presumed inflammatory intracranial arterial vasculopathy

Optimal criteria for diagnosing and monitoring response to treatment for infectious and inflammatory medium–large vessel intracranial vasculitis presenting with stroke are lacking. We integrated intracranial vessel wall MRI with arterial spin labelling into our routine clinical stroke pathway to detect presumed inflammatory intracranial arterial vasculopathy, and monitor disease activity, in patients with clinical stroke syndromes. We used predefined standardized radiological criteria to define vessel wall enhancement, and all imaging findings were rated blinded to clinical details. Between 2017 and 2018, stroke or transient ischaemic attack patients were first screened in our vascular radiology meeting and followed up in a dedicated specialist stroke clinic if a diagnosis of medium–large inflammatory intracranial arterial vasculopathy was radiologically confirmed. Treatment was determined and monitored by a multi-disciplinary team. In this case series, 11 patients were managed in this period from the cohort of young stroke presenters (<55 years). The median age was 36 years (interquartile range: 33,50), of which 8 of 11 (73%) were female. Two of 11 (18%) had herpes virus infection confirmed by viral nucleic acid in the cerebrospinal fluid. We showed improvement in cerebral perfusion at 1 year using an arterial spin labelling sequence in patients taking immunosuppressive therapy for >4 weeks compared with those not receiving therapy [6 (100%) versus 2 (40%) P = 0.026]. Our findings demonstrate the potential utility of vessel wall magnetic resonance with arterial spin labelling imaging in detecting and monitoring medium–large inflammatory intracranial arterial vasculopathy activity for patients presenting with stroke symptoms, limiting the need to progress to brain biopsy. Further systematic studies in unselected populations of stroke patients are needed to confirm our findings and establish the prevalence of medium–large artery wall inflammation.

An international patient-centred study of retroperitoneal fibrosis

BACKGROUND

The impact that rare chronic disorders, such as retroperitoneal fibrosis (RPF), can have on the physical and psychological aspects of a patient's health is poorly understood. Patient-related outcome measures and experiences provide a unique opportunity to understand the impact rare chronic disorders have on a patient's life as well as allowing healthcare providers to compare and improve performance.

AIM

To understand the physical and psychosocial impact that RPF has upon peoples' lives.

DESIGN

An international online questionnaire was therefore created to gain insights into how patients with RPF, a rare fibro-inflammatory condition, viewed their health and experiences.

METHODS

An international online questionnaire comprising 62 questions/free text options, was designed in collaboration with two patient advocates and the multi-disciplinary Renal Association Rare Disease Registry (RaDaR) RPF Group the questionnaire was anonymous and freely accessible on a GOOGLE Form online platform for 6 months.

RESULTS

A total of 229 patients from 30 countries across 5 continents responded. Four key issues were identified; (i) pain; (ii) therapy-related side effects; (iii) lack of informed doctors/information about their condition and its management; and (iv) psychological burden. Variations in diagnosis and management are highlighted with 55% undergoing a biopsy to reach a diagnosis of RPF; 75% of patients underwent a further interventional procedure with 60% concurrently treated medically.

CONCLUSION

This study will guide further development of clinical and academic multi-disciplinary activity and shows the importance of trying to understand the impact of rare chronic disorders on the physical and psychological aspects of a patient's health.

The transcription factor ERG regulates a low shear stress-induced anti-thrombotic pathway in the microvasculature

Endothelial cells actively maintain an anti-thrombotic environment; loss of this protective function may lead to thrombosis and systemic coagulopathy. The transcription factor ERG is essential to maintain endothelial homeostasis. Here, we show that inducible endothelial ERG deletion (ErgiEC-KO) in mice is associated with spontaneous thrombosis, hemorrhages and systemic coagulopathy. We find that ERG drives transcription of the anticoagulant thrombomodulin (TM), as shown by reporter assays and chromatin immunoprecipitation. TM expression is regulated by shear stress (SS) via Krüppel-like factor 2 (KLF2). In vitro, ERG regulates TM expression under low SS conditions, by facilitating KLF2 binding to the TM promoter. However, ERG is dispensable for TM expression in high SS conditions. In ErgiEC-KO mice, TM expression is decreased in liver and lung microvasculature exposed to low SS but not in blood vessels exposed to high SS. Our study identifies an endogenous, vascular bed-specific anticoagulant pathway in microvasculature exposed to low SS.

IgG4-related disease in a multi-ethnic community: clinical characteristics and association with malignancy

BACKGROUND

Immunoglobulin-G4-related disease (IgG4-RD) is a recently recognized fibro-inflammatory condition that can affect multiple organs. Despite growing interest in this condition, the natural history and management of IgG4-RD remain poorly understood.

AIM

To describe the clinical characteristics, treatment and outcomes of IgG4-RD in a multi-ethnic UK cohort, and investigate its possible association with malignancy.

DESIGN

Retrospective analysis of case-note and electronic data.

METHODS

Cases were identified from sub-specialty cohorts and a systematic search of an NHS trust histopathology database using 'IgG4' or 'inflammatory pseudotumour' as search terms. Electronic records, imaging and histopathology reports were reviewed.

RESULTS

In total, 66 identified cases of IgG4-RD showed a similar multi-ethnic spread to the local population of North West London. The median age was 59 years and 71% of patients were male. Presenting symptoms relating to mass effect of a lesion were present in 48% of cases and the mean number of organs involved was 2.4. Total of 10 patients had reported malignancies with 6 of these being haematological. 83% of those treated with steroids had good initial response; however, 50% had relapsing-remitting disease. Rituximab was administered in 11 cases and all achieved an initial serological response. Despite this, seven patients subsequently relapsed after a mean duration of 11 months and four progressed despite treatment.

CONCLUSIONS

We report a large UK-based cohort of IgG4-RD that shows no clear ethnic predisposition and a wide range of affected organs. We discuss the use of serum IgG4 concentrations as a disease marker in IgG4-RD, the association with malignant disease and outcomes according to differing treatment regimens.

P6300Endothelial cell activation by pro-inflammatory cytokines exerts novel paracrine effects on co-cultured cardiomyocytes

Background

Anti-inflammatory therapies have failed to meet expectations in recent clinical trials for heart failure, despite the number of studies demonstrating pro-fibrotic, arrhythmogenic and hypertrophic effects of inflammation. To enlighten this, we sought to examine the contribution of non-myocytes in the cardiac inflammatory response. Endothelial cells (EC) can regulate cardiomyocyte (CM) function with multiple soluble factors. While many studies have shown the effects of pro-inflammatory cytokines on EC or CM separately, it is still unclear how the activation of EC can affect CM function.

Purpose

We studied the effect of pro-inflammatory pre-conditioning of EC on CM in indirect co-culture systems and in an ex vivo model of cardiac tissue. We hypothesised that pro-inflammatory activation of EC would alter the contractility of co-cultured CM.

Methods

Human cardiac microvascular EC were first pre-conditioned for 24h with Cytomix (1 ng/ml TNF-α, 1 ng/ml IL-1β, 25 ng/ml IL-6 Rα/IL-6 chimera) and co-cultured in a transwell system (pore size: 0.4μm) with adult rat ventricular CM. Co-culture supernatants were screened using a Cytokine Profiler Array. In vitro analysis of calcium handling in CM utilised the optical mapping technique and Fluo-4. Contractility of cardiac tissue was measured ex vivo using myocardial slices of 300 μm, prepared from left ventricles of adult rat and cultured for 24h with field stimulation and a fixed stretch producing a sarcomeric length of 2.2 μm.

Results

Treatment of EC by Cytomix prior to co-cultures induced a release of CC and CXC chemokines, G-/GM-CSF, ST2 and the adhesion molecule ICAM-1. Using published RNAseq datasets we noticed that adult CM do not constitutively express the receptors for the chemokines identified with the Profiler Array. However, duration of calcium transients in CM was significantly reduced from 454 to 322 ms in co-cultures with EC pre-conditioned by Cytomix, compared to untreated EC. Amplitude and time to peak were unchanged. In contrast, myocardial slices treated with Cytomix demonstrated a significant increase in contractility compared to control (from 3.3 to 5.3 mN/mm2) but no significant change in the duration of contraction (from 467 to 434 ms) or the rate of relaxation.

Conclusions

Pre-conditioned EC exert paracrine effects on the calcium handling of isolated CM, suggesting pro-inflammatory activation of proximal EC can affect CM function. In myocardial slices, pro-inflammatory stimulation provoked an inotropic response. The divergence of effect with findings in isolated cells may reflect differences in experimental design and multicellularity. Future work will aim to characterise the soluble mediators involved, and selectively target EC in slices to contextualise the effects described in co-cultures. Ultimately, this may inform the development of novel anti-inflammatory strategies for clinical use.

Acknowledgement/Funding

British Heart Foundation

A low balance between microparticles expressing tissue factor pathway inhibitor and tissue factor is associated with thrombosis in Behçet's Syndrome

Thrombosis is common in Behçet's Syndrome (BS), and there is a need for better biomarkers for risk assessment. As microparticles expressing Tissue Factor (TF) can contribute to thrombosis in preclinical models, we investigated whether plasma microparticles expressing Tissue Factor (TF) are increased in BS. We compared blood plasma from 72 healthy controls with that from 88 BS patients (21 with a history of thrombosis (Th+) and 67 without (Th-). Using flow cytometry, we found that the total plasma MP numbers were increased in BS compared to HC, as were MPs expressing TF and Tissue Factor Pathway Inhibitor (TFPI) (all p < 0.0001). Amongst BS patients, the Th+ group had increased total and TF positive MP numbers (both p ≤ 0.0002) compared to the Th- group, but had a lower proportion of TFPI positive MPs (p < 0.05). Consequently, the ratio of TFPI positive to TF positive MP counts (TFPI/TF) was significantly lower in Th+ versus Th- BS patients (p = 0.0002), and no patient with a TFPI/TF MP ratio >0.7 had a history of clinical thrombosis. We conclude that TF-expressing MP are increased in BS and that an imbalance between microparticulate TF and TFPI may predispose to thrombosis.

Synthesis of β-Enantiomers of N4-Hydroxy-3′-Deoxy-Pyrimidine Nucleosides and Their Evaluation against Bovine Viral Diarrhoea Virus and Hepatitis C Virus in Cell Culture

N4-Hydroxycytidine (NHC) was recently reported to have anti-pestivirus and anti-hepacivirus activity. It is thought that this nucleoside acts as a weak alternative substrate for the hepatitis C virus (HCV) polymerase. In addition to NHC, 3′-deoxyuridine (3′-dU) was found to inhibit bovine diarrhoea virus (BVDV) production by 1 log10 at 37.2 μM. These initial findings prompted the synthesis of β-D and β-L analogues of (i) base-modified 3′-deoxy-NHC; (ii) 3′-deoxyuridine; and 3′-deoxycytidine. The antiviral activity of these 42 nucleosides was evaluated against BVDV and HCV bicistronic replicon in cell culture. Among the NHC analogues, the antiviral activity observed for the β-L-3′-deoxy-5-fluoro-derivative 1-(3-deoxy-β-L- erythro-pentofuranosyl)-5-fluoro-4-hydrox-yaminopyrimidin-2( 1H)-one and the β-D-3′-deoxy-5-iodo-derivative 1-(3-deoxy-β-D-erythro-pentofuranosyl)-5-iodocytosine in the replicon system (1 log10 reduction at 100 μM) was due to the concomitant toxicity towards intracellular ribosomal RNA levels (CC90 equal or lower than the EC90). In conclusion, none of the newly synthesized derivatives exhibited enhanced antiviral activity compared to the parent nucleoside NHC.

Methotrexate-mediated activation of an AMPK-CREB-dependent pathway: a novel mechanism for vascular protection in chronic systemic inflammation

Aims

Premature cardiovascular events complicate chronic inflammatory conditions. Low-dose weekly methotrexate (MTX), the most widely used disease-modifying drug for rheumatoid arthritis (RA), reduces disease-associated cardiovascular mortality. MTX increases intracellular accumulation of adenosine monophosphate (AMP) and 5-aminoimidazole-4-carboxamide ribonucleotide which activates AMP-activated protein kinase (AMPK). We hypothesised that MTX specifically protects the vascular endothelium against inflammatory injury via induction of AMPK-regulated protective genes.

Methods/results

In the (NZW×BXSB)F₁ murine model of inflammatory vasculopathy, MTX 1 mg/kg/week significantly reduced intramyocardial vasculopathy and attenuated end-organ damage. Studies of human umbilical vein endothelial cells (HUVEC) and arterial endothelial cells (HAEC) showed that therapeutically relevant concentrations of MTX phosphorylate AMPKα^Thr172, and induce cytoprotective genes including manganese superoxide dismutase (MnSOD) and haem oxygenase-1 (HO-1). These responses were preserved when HUVECs were pretreated with tumour necrosis factor-α to mimic dysfunctional endothelium. Furthermore, MTX protected against glucose deprivation-induced endothelial apoptosis. Mechanistically, MTX treatment led to cyclic AMP response element-binding protein (CREB)^Ser133 phosphorylation, while AMPK depletion attenuated this response and the induction of MnSOD and HO-1. CREB siRNA inhibited upregulation of both cytoprotective genes by MTX, while chromatin immunoprecipitation demonstrated CREB binding to the MnSOD promoter in MTX-treated EC. Likewise, treatment of (NZW×BXSB)F₁ mice with MTX enhanced AMPKα^Thr172 phosphorylation and MnSOD, and reduced aortic intercellular adhesion molecule-1 expression.

Conclusions

These data suggest that MTX therapeutically conditions vascular endothelium via activation of AMPK-CREB. We propose that this mechanism contributes to the protection against cardiovascular events seen in patients with RA treated with MTX.

Optimizing the outcome of vascular intervention for Takayasu arteritis

Background

Takayasu arteritis (TA) predisposes to the development of arterial stenoses and aneurysms, and is associated with considerable morbidity and mortality amongst young patients. The aims of this study were to analyse indications and outcomes of surgical intervention, and to assess the potential benefits of immunosuppression and the use of perioperative imaging.

Methods

This was a retrospective review of patients with TA referred between 2001 and 2012.

Results

A series of 97 patients with TA, seen at a single tertiary centre, is reported. Immunosuppression was required in 87 patients (90 per cent). Thirty-seven (38 per cent) underwent 64 procedures: 27 patients underwent 33 open surgical procedures and 20 patients had 31 endovascular procedures. After a median follow-up of 6 years, the overall success rate was 79 per cent for open surgery (mean graft patency 9·4 years) and 52 per cent for endovascular procedures (P = 0·035). Procedural failure was significantly reduced in patients receiving preoperative immunosuppression, and particularly endovascular procedures (P = 0·001). In addition to clinical examination and measurement of acute-phase reactants, combination non-invasive imaging including Doppler ultrasonography, [18F]fluorodeoxyglucose combined positron emission and computed tomography (CT), magnetic resonance angiography and CT angiography was used to identify arterial lesions, establish the diagnosis and monitor treatment outcomes.

Conclusion

Outcomes of vascular intervention in TA may be improved by detailed preoperative assessment including measurement of disease activity, and by ensuring optimal immunomodulatory therapy before and after the procedure.

Synthesis and biological evaluation of (3'S)-3'-deoxy-3'-fluoro-3'-C-ethynylcytidine

The novel pyrimidine nucleoside, (3'S)-3'-deoxy-3'-fluoro-3'-C-ethynylcytidine (1) was synthesized from cytidine in seven steps. The key step in the synthesis was the introduction of the tertiary fluorine at the 3'-position. Compound 1 was evaluated in vitro against several RNA viruses.

Statin-mediated cytoprotection of human vascular endothelial cells: a role for Kruppel-like factor 2-dependent induction of heme oxygenase-1

BACKGROUND

Heme oxygenase-1 (HO-1), by exerting anti-inflammatory, antiproliferative, antiapoptotic and antioxidant effects in the vasculature, protects against atherosclerosis and post-transplant vasculopathy. We noted the overlap between the effects of HO-1 and those attributed to 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins). This led to an investigation of the role of HO-1 in statin-mediated cytoprotection in primary human endothelial cells (ECs), and the ability of Kruppel-like factor 2 (KLF2) to regulate HO-1 function.

METHODS/RESULTS

Treatment of human umbilical vein and aortic ECs with atorvastatin significantly upregulated HO-1 promoter activity, mRNA expression and protein expression, increasing HO-1 enzymatic activity as shown by raised intracellular bilirubin IXalpha. This effect was indirect, dependent upon inhibition of HMG-CoA reductase and geranylgeranylation, and independent of nitric oxide or changes in mRNA stability. Atorvastatin protected ECs against the generation of reactive oxygen species and H(2)O(2)-induced injury. HO-1 inhibition, with small interfering RNA (siRNA) or zinc protoporphyrin IX, abrogated atorvastatin-mediated cytoprotection. Atorvastatin upregulated KLF2 expression, whereas KLF2 siRNA attenuated statin-induced HO-1 and its associated antioxidant cytoprotective effects. Iron chelation, adenoviral-mediated overexpression of ferritin or supplementation of culture media with biliverdin reversed the inhibitory effects of HO-1 and KLF2 siRNA, suggesting that bile pigments and ferritin mediate the antioxidant actions of statin-induced HO-1.

CONCLUSIONS

We have identified a novel link between KLF2 and HO-1 in human vascular ECs, demonstrating that atorvastatin-mediated HO-1 upregulation, and its associated antioxidant effect, is KLF2-dependent. The relationship between KLF2 and HO-1 is likely to represent an important component of the vasculoprotective profile of statins.

Heptamethine cyanine dyes with a robust C-C bond at the central position of the chromophore

Novel, highly fluorescent, monofunctional, water-soluble heptamethine cyanine dyes containing a robust C-C bond at the central position of the near-infrared fluorophore system were prepared by the Suzuki-Miyaura method. The reaction proceeded efficiently to replace the meso-chlorine atom with a carboxy-functionalized aryl moiety and afforded the desired compounds in high yields. This methodology is particularly attractive due to its versatility and the utilization of environmentally friendly water as solvent. The new compounds possess excellent spectral properties and readily label bioactive molecules on solid support. The results demonstrate the potential of using the new compounds as fluorescent antennae for molecular imaging, spectroscopy, microscopy, and chemical or biological molecular recognition studies.

Takayasu's arteritis--recent advances in imaging offer promise

Takayasu's arteritis (TA), a rare large vessel vasculitis of unknown aetiology, remains a difficult disease to manage with diagnosis often delayed until the late occlusive stage when irreversible vascular damage has occurred. Recent studies suggest that non-invasive imaging modalities including magnetic resonance imaging, ultrasound and 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) allow diagnosis of TA earlier in the disease course than standard angiography and provide a means for monitoring disease activity. Choice of appropriate therapy for TA is limited by a lack of evidence and a combination of corticosteroids and immunosuppressive drugs is most commonly used. Novel therapeutic approaches such as the use of anti-tumour necrosis factor alpha (TNF-alpha) inhibitors and drug-eluting arterial stents show promise for improving the prognosis in severe disease. In addition, strict management of traditional cardiovascular risk factors such as dyslipidaemia, hypertension and lifestyle factors is mandatory to minimize secondary cardiovascular complications, which are the major cause of death in this disease.

Both Fcgamma and complement receptors mediate transfer of immune complexes from erythrocytes to human macrophages under physiological flow conditions in vitro

Abnormal clearance by the mononuclear phagocytic system of immune complexes (IC) is important in the pathogenesis of systemic lupus erythematosus (SLE). We have developed an in vitro model to investigate the cellular mechanisms involved in the transfer of soluble IC from erythrocytes to human macrophages under physiological flow conditions. In this assay, erythrocytes bearing fluorescently labelled IC are perfused over monolayers of human monocytes or monocyte-derived macrophages in a parallel-plate flow chamber, and transfer quantified using confocal microscopy and flow cytometry. Using aggregated human IgG as a model IC, we have been able to demonstrate transfer of IC from erythrocytes to macrophages. Blocking studies with specific neutralizing antibodies have shown that both complement and Fcgamma receptors are required for IC transfer. Blockade of CR4 (alpha(x)beta(2) integrin), FcgammaRIIa or FcgammaRIII reduced transfer, while anti-CR3 (alpha(m)beta(2) integrin) had no effect. Blockade of CR3, FcgammaRIIa or FcgammaRIII also reduced the number of adhesive interactions between fluorescently labelled IC-bearing erythrocytes and macrophage monolayers. Taken together with the transfer data, this suggests differing roles for these receptors in the human IC transfer reaction that includes an adhesive function which facilitates IC processing by mononuclear phagocytes. Finally, a functional effect of the FcgammaRIIa R131/H131 polymorphism, important in susceptibility to SLE, has also been demonstrated using this model. Uptake of IgG(2) but not IgG(1)-containing soluble IC was reduced by macrophages from individuals homozygous for the R131 allelic variant of the receptor.

Peritoneal mesothelioma: an unusual cause of an acute phase response presenting to the rheumatologist

The presence of an acute phase response may pre-date the eventual diagnosis of malignant disease by months or even years. We describe two patients referred to the rheumatology clinic, in which extensive investigation failed to identify an underlying cause to account for the presenting symptoms and an associated acute phase response. Several months later, repeated abdominal CT scans revealed an abnormality and subsequent laparoscopic biopsy confirmed a diagnosis of peritoneal mesothelioma.

Takayasu's arteritis: a cause of prolonged arterial stiffness

OBJECTIVES

Cardiovascular disease is a major cause of mortality and morbidity in patients with Takayasu's arteritis (TA). Increased arterial stiffness is an independent risk factor and predictor of cardiovascular mortality in a variety of diseases. Pulse wave velocity (PWV) and the augmentation index (AI) are used as clinical measurements of arterial stiffness.

METHODS

Data are presented from 10 patients with TA and 11 normal controls obtained between 2000 and 2004. Arterial compliance was assessed non-invasively by measurement of PWV, using the Complior system, and calculation of the aortic AI.

RESULTS

TA patients (mean age 40.8+/-13.2 yr) were compared with a control group of healthy women from a parallel study (mean age 32.3+/-5.5 yr). The mean carotid-femoral PWV (PWV-CF) was higher in TA patients (P = 0.03). In addition, both aortic AI derived from the radial artery (P = 0.002) and carotid AI (P = 0.03) were higher in TA patients compared with controls. PWV-CF did not correlate with CRP (r = - 0.23, P = 0.23) or ESR (r = - 0.19, P = 0.27). Similar results were obtained for the correlation of carotid-radial PWV with CRP (r = 0.15, P = 0.32) and ESR (r = 0.33, P = 0.14).

CONCLUSIONS

Our data show that TA is associated with elevated arterial stiffness in the central aorta, which may persist when the disease is quiescent. These data suggest that PWV represents a means by which cardiovascular risk can be detected and monitored in TA, and highlights the importance of effective management of cardiovascular risk factors in these patients.

Synthesis and antiviral activity of 2'-deoxy-2'-fluoro-2'-C-methyl purine nucleosides as inhibitors of hepatitis C virus RNA replication

A series of purine nucleosides containing the 2'-deoxy-2'-fluoro-2'-C-methylribofuranosyl moiety were synthesized and evaluated as potential inhibitors of the hepatitis C virus in vitro. Of the nucleosides that were synthesized, only those possessing a 2-amino group on the purine base reduced the levels of HCV RNA in a subgenomic replicon assay.

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.