'Aquaporin-omics': mechanisms of aquaporin-2 loss in polyuric disorders

Animal models of a variety of acquired nephrogenic diabetes insipidus (NDI) disorders have identified a common feature: all such models are associated with the loss of aquaporin-2 (AQP2) from collecting duct principal cells, explaining the associated polyuria. To discover mechanisms of AQP2 loss, previous investigators have carried out either transcriptomics (lithium-induced NDI, unilateral ureteral obstruction, endotoxin-induced NDI) or proteomics (hypokalaemia-associated NDI, hypercalcaemia-associated NDI, bilateral ureteral obstruction), yielding contrasting views. Here, to address whether there may be common mechanisms underlying loss of AQP2 in acquired NDI disorders, we have used bioinformatic data integration techniques to combine information from all transcriptomic and proteomic data sets. The analysis reveals roles for autophagy/apoptosis, oxidative stress and inflammatory signalling as key elements of the mechanism that results in loss of AQP2. These processes can cause AQP2 loss through the combined effects of repression of Aqp2 gene transcription, generalized translational repression, and increased autophagic degradation of proteins including AQP2. Two possible types of stress-sensor proteins, namely death receptors and stress-sensitive protein kinases of the EIF2AK family, are discussed as potential triggers for signalling processes that result in loss of AQP2. KEY POINTS: Prior studies have shown in a variety of animal models of acquired nephrogenic diabetes insipidus (NDI) that loss of the aquaporin-2 (AQP2) protein is a common feature. Investigations of acquired NDI using transcriptomics (RNA-seq) and proteomics (protein mass spectrometry) have led to differing conclusions regarding mechanisms of AQP2 loss. Bioinformatic integration of transcriptomic and proteomic data from these prior studies now reveals that acquired NDI models map to three core processes: oxidative stress, apoptosis/autophagy and inflammatory signalling. These processes cause loss of AQP2 through translational repression, accelerated degradation of proteins, and transcriptional repression.

Circadian gene expression in mouse renal proximal tubule

Circadian variability in kidney function is well recognized but is often ignored as a potential confounding variable in physiological experiments. Here, we have created a data resource consisting of expression levels for mRNA transcripts in microdissected proximal tubule segments from mice as a function of the time of day. Small-sample RNA sequencing was applied to microdissected S1 proximal convoluted tubules and S2 proximal straight tubules. After stringent filtering, the data were analyzed using JTK-Cycle to detect periodicity. The data set is provided as a user-friendly webpage at https://esbl.nhlbi.nih.gov/Databases/Circadian-Prox2/. In proximal convoluted tubules, 234 transcripts varied in a circadian manner (4.0% of the total). In proximal straight tubules, 334 transcripts varied in a circadian manner (5.3%). Transcripts previously known to be associated with corticosteroid action and with increased flow were found to be overrepresented among circadian transcripts peaking during the "dark" portion of the day [zeitgeber time (ZT)14-22], corresponding to peak levels of corticosterone and glomerular filtration rate in mice. To ask whether there is a time-of-day dependence of protein abundances in the kidney, we carried out LC-MS/MS-based proteomics in whole mouse kidneys at ZT12 and ZT0. The full data set (n = 6,546 proteins) is available at https://esbl.nhlbi.nih.gov/Databases/Circadian-Proteome/. Overall, 293 proteins were differentially expressed between ZT12 and ZT0 (197 proteins greater at ZT12 and 96 proteins greater at ZT0). Among the regulated proteins, only nine proteins were found to be periodic in the RNA-sequencing analysis, suggesting a high level of posttranscriptional regulation of protein abundances.NEW & NOTEWORTHY Circadian variation in gene expression can be an important determinant in the regulation of kidney function. The authors used RNA-sequencing transcriptomics and LC-MS/MS-based proteomics to identify gene products expressed in a periodic manner. The data were used to construct user-friendly web resources.

POS0200 POST-mRNA VACCINE FLARES IN AUTOIMMUNE INFLAMMATORY RHEUMATIC DISEASES: INTERIM RESULTS FROM THE CORONAVIRUS NATIONAL VACCINE REGISTRY FOR IMMUNE DISEASES SINGAPORE (CONVIN-SING)

Background

Published data suggest no increased rate of flare of autoimmune inflammatory rheumatic diseases (AIIRD) after COVID-19 mRNA vaccination; however, the studies are limited by small sample size, short follow up or at risk of selection bias (voluntary physician reports or patient surveys).

Objectives

To study flares of AIIRD within three months of the first dose of an anti-SARS-COV2 mRNA vaccine.

Methods

A retrospective cohort study of consecutive AIIRD patients ≥ 12 years old, across six public hospitals in Singapore who received at least one dose of an mRNA (Pfizer/BioNTech or Moderna) vaccine. Data were censored at the first post-vaccine clinic visit when the patient had flared or if ≥ three months had elapsed since the first dose of the vaccine, whichever came first. Predictors of flare were determined by Cox proportional hazards analysis and time to flare was examined using a Nelson Aalen cumulative hazard estimate (Figure 1).

Figure 1.

Nelson-Aalen curve of flares over time

Results

2339 patients (74% Chinese, 72% female) of median (IQR) age 64 (53, 71) years were included in the interim analysis (Table 1). 2112 (90%) had the Pfizer/BioNTech vaccine and 195 (8%) had Moderna, with a median (IQR) interval of 21 (21, 23) days between the two doses. The most common AIIRD diagnoses were Rheumatoid arthritis (1063, 45%), Psoriatic arthritis (296, 12.6%) and Systemic lupus erythematosus (SLE) (288, 12.3%). 186 (8%) were treated with biologics/ targeted disease modifying agents. 2125 (91%) patients were in low disease activity or remission. Treatment was interrupted for vaccination in only 18 (0.8%) patients. Seven (0.3%) patients had previous COVID-19 infection.

Table 1.

Patient characteristics

Baseline characteristicsNo flares(n = 1887, %)Flares within 0—3 months of 1st vaccine dose (n= 272, %)Flares outside of 0 – 3 months after 1st vaccine dose (n = 180, %)Age (median years, IQR)64 (53, 71)61 (50, 69)65 (55, 71)RaceChinese1386 (73)206 (76)129 (72)Malay193 (10)28 (10)20 (11)Indian195 (10)27 (10)26 (14)GenderFemale1367 (72)200 (74)117 (65)Vaccine typePfizer/BioNTech1713 (92)239 (90)160 (90)Moderna149 (8)28 (10)18 (10)DiagnosisRheumatoid Arthritis831 (44)139 (51)93 (52)Systemic Lupus Erythematosus269 (14)20 (7)9 (5)Psoriatic Arthritis225 (12)42 (15)29 (16)Spondyloarthropathies141 (7)21 (7)17 (9)Sjogren’s Syndrome114 (6)15 (6)8 (4)Systemic sclerosis94 (5)4 (1)6 (3)Baseline Physician Disease ActivityRemission1007 (53)99 (36)63 (35)Low Disease Activity731 (39)128 (47)97 (54)Moderate Disease Activity134 (7)40 (15)20 (11)High Disease Activity15 (1)5 (2)0

452 (19%) flares were recorded during 9798.8 patient-months [4.6/100 patient-months, median (IQR) follow up duration 4.2 (3.3, 5.3) months], of which 272 (11.6%) patients flared within the 3-month period of interest and 180 (7.7%) flared outside of the 3-month period (Table 1). Median (IQR) time-to-flare was 40.5 (18, 56.6) days. 60 (22.1%) were mild and self-limiting, 170 (62.5%) were mild-moderate and 42 (15.4%) were severe. 190 (69.8%) of those who flared required escalation of treatment and 15 (5.5%) required hospital admission. 239 (10.2%) had improved disease activity after the vaccine.

On multivariate Cox regression analysis, patients in the oldest age tertile [median (IQR) 74 (71, 79) years] were less likely to flare [HR 0.80 (95% CI 0.63, 1.00), p = 0.05] Patients with inflammatory arthritis (compared with connective tissue disease, vasculitis and others) and patients with baseline active disease were more likely to flare [HR 1.72 (95% CI 1.35, 2.20), p < 0.001 and 1.82 (95% CI 1.39, 2.39), p < 0.001 respectively]

Conclusion

There was a moderately high rate of AIIRD flares after mRNA vaccination; however, there was no clustering of flares in the immediate post-vaccine period to suggest causality. Older patients were less likely to flare, while those with inflammatory arthritis and active disease at baseline were more likely to flare.

Disclosure of Interests

Margaret Ma Grant/research support from: Support grant from multiple companies for the Singapore Biologics registry, Amelia Santosa Speakers bureau: Amgen Talk, Consultant of: Pfizer ad board, Kok Ooi Kong: None declared, Chuanhui Xu: None declared, Johnston Tang Gin Xiang: None declared, Gim Gee Teng Speakers bureau: Boehringer Ingleheim, Anselm Mak Speakers bureau: J&J and GSK, Grant/research support from: GSK - the supported studies programme, Sen Hee Tay: None declared, Victoria Wei Wen Ng: None declared, Joshua Zhi En Koh: None declared, Warren Fong Speakers bureau: speaker for Abbvie, DKSH, GSK, Novartis, Li-Ching Chew Speakers bureau: pfizer and Abbvie, Consultant of: Pfizer and Abbvie Advisory Board meeting, Grant/research support from: Abbvie educational grant for ultrasound conference, Andrea Low Speakers bureau: Boehringer Ingeilheim, Consultant of: Consultant/steering group committee for BI and J&J, annie law: None declared, Yih Jia Poh: None declared, Siaw Ing Yeo Grant/research support from: Multiple pharmaceutical companies for the support of the National Biologics Registry, Ying Ying Leung Speakers bureau: Abbvie, DKSH, Jassen, Novartis and Pfizer, Wei-Rui Goh: None declared, Chuah Tyng Yu: None declared, Nur Emillia Roslan: None declared, Stanley Angkodjojo Speakers bureau: Boehringer Ingeilheim, Consultant of: Abbvie and DKSH, Kee Fong Phang: None declared, Thaschawee Arkachaisri: None declared, Melonie Sriranganathan: None declared, Teck Choon TAN: None declared, Peter Cheung Consultant of: Ad board for Boehringer Ingleheim, novartis, janssen and abbvie, Grant/research support from: Novartis, Manjari Lahiri Speakers bureau: J&J, DSKH, Consultant of: DSKH, Gilead, Grant/research support from: Multiple pharma companies contributed to the Singapore Biologics registry

Novartis

POS0763 A MULTIMODAL MAGNETIC RESONANCE IMAGING STUDY OF COGNITIVE FUNCTION IN SYSTEMIC LUPUS ERYTHEMATOSUS: A MACHINE LEARNING APPROACH

Background

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disorder that can affect the central nervous system. Cognitive dysfuncion is the most common neuropsyhiatric event in SLE patients, yet it is also one of the hardest to diagnose.

Objectives

To investigate if multimodal imaging to assess anatomical magnetic resonance imaging (MRI) abnormalities in the brains of SLE patients can predict cognitive function.

Methods

Subjects underwent voxel-based morphometry (VBM), magnetization transfer imaging (MTI), and dynamic contrast-enhanced (DCE) MRI. Automated Neuropsychological Assessment Metrics (ANAM) was used to assess cognitive function in this cross-sectional study and the primary measure was the total throughput score (TTS). TTS is the total of the throughput scores for each of the 8 ANAM subtests: (i) code substitution learning (CSL); (ii) code substitution immediate (CSI); (iii) code substitution delayed (CSD); (iv) spatial processing (SP); (v) matching to sample (MSP); (vi) running memory continuous performance test (CPT); (vii) mathematical processing (MTH) and (viii) memory search (MS). Olfactory assessment was done using the University of Pennsylvania Smell Identification Test. We used a machine learning-based model (i.e. GLMnet) to predict TTS. Subjects with active SLE disease or above 40 years old were excluded.

Results

Thirty SLE patients [26 female, 32.0 (26.8-37.0) years] without clinically overt neuropsychiatric manifestations and 10 healthy controls (HCs) [9 females, 27.0 (23.0-31.5) years] were enrolled in this study. Both groups had comparable cognitive and olfactory functions. No significant differences were observed in VBM, MTR, olfactory blub and tract (OBT) volume in SLE patients compared to HCs. We observed increased blood-brain barrier (BBB) permeability parameters (Ktrans and PS) in several regions of SLE patients. DCE-MRI perfusion parameters such as perfusion (F) and vp but not permeability measures were associated with TTS. In particular, F right amygdala correlated with TTS in SLE patients (r = 0.636, FDR p < 0.05) (Table 1). Using GLMnet, we trained a multimodal MRI model comprising of VBM, MTR, DCE-MRI and OBT volume parameters to predict TTS in SLE patients (r = 0.998, p < 0.0005) (Figure 1).

Figure 1.

Machine learning-based models to predict cognitive function.

Table 1.

Correlation between ANAM tests with perfusion (F) in SLE patients, ranked in descending order of statistical significance for TTS.

VariableTTSCSLCSICSDSPMSPCPTMTHMSF right amygdala0.636‡*0.520‡0.3370.437†0.559‡0.3230.633‡0.412†0.598‡F left entorhinal0.504‡0.422†0.3660.416†0.3050.1850.530‡0.1860.416†F left amygdale0.495‡0.400†0.1890.378†0.3300.2370.491‡0.376†0.449†F choroid0.469†0.384†0.2160.413†0.458†0.2020.456†0.3400.406†plexusF right rostal anterior cingulate0.453†0.3010.1180.2960.393†0.2140.547‡0.420†0.383†F right entorhinal0.448†0.368†0.2320.3120.376†0.1560.438†0.2710.407†F cerebellum white matter0.427†0.3580.2010.370†0.2730.0780.449†0.2900.297F left hippocampus0.427†0.3550.1340.390†0.3560.2030.511‡0.3360.332F brain stem0.407†0.2980.1380.2750.2940.1530.478‡0.3080.369†F right insula0.407†0.3080.0740.3000.3240.1760.437†0.3230.347F left parietal0.400†0.2630.0920.2540.2940.2240.487‡0.2740.332F ventricles0.396†0.3030.0830.3210.370†0.1920.477‡0.2860.361F right temporal0.395†0.2800.1130.2810.2880.1670.477‡0.3220.331F right hippocampus0.395†0.3070.0770.3250.3560.1900.486‡0.3570.339F right parietal0.376†0.2490.0820.2740.2830.1390.460†0.2550.311F right parahippocampal gyrus0.375†0.3530.1190.3020.3410.2410.3530.2080.273

† p < 0.05, ‡ p < 0.01, *FDR p < 0.05

Conclusion

These findings suggest that the BBB may be affected early in the course of cognitive dysfunction, even preceding detectable changes in other MRI sequences and machine learning algorithms can be used to predict TTS measures, even in asymptomatic SLE patients.

References

Nil.

Disclosure of Interests

Sen Hee Tay: None declared, Mary Stephenson: None declared, Nur Azizah Allameen: None declared, Sriram Narayanan: None declared, Bernett Lee: None declared, Anselm Mak Speakers bureau: JnJ Apr 2019 and GSK Jan 2022, Grant/research support from: GSK - The Supported Studies Programme

FRI0033 ANTI-CARBAMYLATED PROTEIN POSITIVITY PREDICTS DAS28-REMISSION AT 12 MONTHS IN PATIENTS WITH EARLY RHEUMATOID ARTHRITIS: RESULTS FROM THE SINGAPORE EARLY ARTHRITIS COHORT

Background:

Anti-carbamylated protein antibody (anti-carp) positivity has been associated with poorer outcomes in Western cohorts of early rheumatoid arthritis; however, it is unknown if this applies to Asians.

Objectives:

We determined whether anti-carp predicted DAS28-remission, disability and radiographic progression in a multi-ethnic Asian ERA cohort.

Methods:

Patients with physician diagnosed ERA (symptom duration ≤1 year) were recruited from the Singapore Early Arthritis Cohort (n= 317) by convenience sampling. Serum anti-carp was measured cross-sectionally using a commercial ELISA (SincereBio). The test was repeated in 40 healthy individuals to establish the optimal sensitivity and specificity for the diagnosis of RA via a receiver operating curve. Disease activity (DAS28-ESR or DAS28-CRP) was recorded at baseline, 3, 6 and 12 months. Two independent accessors quantified the radiographic damage at baseline and at follow-up using the modified Sharp van der Heijde score (mSS). We used multivariable logistic regression to determine whether anti-carp predicted the following outcomes; (i) DAS-28 remission at 12 months, (ii) any disability (mHAQ>0) at 12 months and (iii) radiographic progression (any increase in the mSS). In each regression model, we chose covariates known to influence the dependent variable in our cohort or from literature.

Results:

One hundred patients were recruited, of mean age (SD) 49.8 (12.5) years, median (IQR) disease duration 10.2 (6.9-15.1) weeks at cohort entry and baseline median DAS-28 4.5 (2.9-5.9) (Table 1). The anti-carp assay was performed after a median (IQR) disease duration of 2.24 (1.82-3.14) years. 93 patients had baseline hand radiographs and 66 had follow-up hand radiographs after ≥ 12 months. Receiver operating characteristics curve yielded optimal sensitivity (95%) and specificity (60%) for the diagnosis of RA at 1.60OD. Therefore, 60 patients were anti-carp positive and 35 patients (37.2%) were positive for RF, ACPA and anti-carp (Figure 1). Anti-carp positivity independently predicted DAS28-remission at 12 months (OR 3.41, 95% CI 1.08-10.7,p=0.04) (Table 2). Anti-carp positivity did not predict disability at 12 months (OR 0.61, 95% CI 0.18-2.07,p=0.43) or radiographic progression (OR 0.23, 95% CI 0.03-2.03,p=0.18).

Table 1.

Predictors of DAS28-remission at 12 months

VariableN (%)Univariable Logistic RegressionMultivariable Logistic RegressionORpOR (CI)SEpAnti-carp60 (60)3.0 (1.31−6.88)0.013.41 (1.08−10.7)1.990.04SerologyRF and ACPA negative31 (33.0)RefEither RF or ACPA positive11 (11.7)0.99 (0.25−3.93)0.991.10 (0.17−7.04)1.040.92RF and ACPA positive52 (55.3)1.12 (0.45−2.75)0.800.89 (0.28−2.81)0.520.84Baseline DAS28Remission17 (17.4)RefLow DA10 (10.2)0.50 (0.05−4.67)0.540.13 (0.01−1.67)0.170.12Mod DA32 (32.7)0.29 (0.05−1.65)0.160.10 (0.02−0.68)0.100.02High DA39 (39.8)0.18 (0.04−0.90)0.040.06 (0.01−0.41)0.06<0.01Combination csDMARDs or biologic DMARD74 (74)1.13 (0.46−2.76)0.801.97 (0.58−6.67)1.230.28Radiographic damage at baseline11 (20)1.79 (0.65−4.95)0.261.27 (0.33-4.95)0.880.73Tertiary education23 (38.3)0.77 (0.34-1.77)0.540.42 (0.12-1.45)0.270.17EthnicityChinese42 (70)RefMalay39 (68.4)0.61 (0.22-1.71)0.350.56 (0.14-2.25)0.400.41Indian8 (13.3)0.60 (0.20-1.77)0.350.79 (0.20-3.13)0.560.74Females46 (76.7)0.43 (0.17-1.11)0.080.48 (0.13-1.85)0.330.29

Conclusion:

Contrary to previous studies done on Western cohorts where anti-carp predicted worse outcomes, anti-carp positivity predicted DAS28-remission at 12 months in our multi-ethnic Asian cohort. This suggests that different genetic and environmental determinants account for anti-carp expression in patients with RA.

Disclosure of Interests:

Jiacai Cho: None declared, Anselm Mak Speakers bureau: Professor Anselm Mak has been paid as a speaker for Johnson & Johnson., Sachin Agrawal: None declared, Preeti Dhanasekaran: None declared, Lay Kheng Teoh: None declared, Peter Cheung: None declared, Manjari Lahiri Grant/research support from: Manjari Lahiri is the site principal investigator for the Singapore National Biologics Register, which is a multi-pharmaceutical funded register, in which industry sponsors provide support through the Chapter of Rheumatologists, Singapore. Dr Lahiri does not personally receive any remuneration.

Minimally invasive rehabilitation of the worn dentition: a case report utilising adhesive additive techniques and digital technologies

The management of the worn dentition presents an increasing challenge that is encountered more frequently in daily dental practice. The consequences of tooth wear tend to be multifactorial and while they may initially only involve the loss of surface enamel it can progressively lead to significant destruction of the dentition. This paper discusses the management of a tooth wear case where a significant amount of tooth structure has been lost from both the anterior and posterior teeth. Protocols for assessment, treatment planning and restorative management of the tooth wear case are presented demonstrating the use of adhesive additive techniques and digital technologies to achieve functional and aesthetic rehabilitation of the dentition.

Renal damage in systemic lupus erythematosus: a comparative analysis of different age groups

Renal damage in systemic lupus erythematosus: a comparative analysis of different age groups A Mak, CC Mok, WP Chu, CH To, SN Wong and TC Au Please note that the following pdf is a corrected version of the article which appears in the printed version of Lupus 16/1. An Erratum will also appear in print in Lupus; 16(2). The corrected line can be found in the abstract. It was changed from: Patients were categorized into childhood (age ≥6 years), adult (between 16 and 50 years) or late onset (≥50 years) SLE. To: Patients were categorized into childhood (age 16 years), adult (between 16 and 50 years) or late onset (50 years) SLE.The objective of this study was to compare the frequency and severity of renal damage in systemic lupus erythematosus (SLE) with regard to the age of disease onset. Among 287 patients with new onset SLE diagnosed between 1991 and 2003 in our hospital, we identified those who fulfilled the American College of Rheumatology (ACR) criteria for renal involvement. Patients were categorized into childhood (age <6 years), adult (between 16 and 50 years) or late onset (≥50 years) SLE. Clinical presentation of renal disease and cumulative renal damage as assessed by the renal domain of the Systemic Lupus International Collaborating Clinics/ACR damage index (SDI) were compared. A linear regression model was constructed to study the effect of age on renal damage. One-hundred and forty-nine patients were studied (134 women and 15 men), including 28 childhood, 107 adult and 14 late onset SLE patients. The mean age of SLE onset was 29.7 ± 14 years. The prevalence of renal disease was 53% in childhood onset, 50% in adult onset and 58% in late onset SLE patients (P = 0.66). At renal disease presentation, late onset SLE patients had significantly lower creatinine clearance and were more likely to be hypertensive. Histological classes of nephritis and initial treatment response, however, did not differ significantly among the patients. After a mean observation of 80.3 months, 32 (21%) patients developed renal damage (renal SDI ≥ 1). Late onset SLE patients had accrued more renal damage than the others. In a multiple regression model, age was not a significant determinant of renal damage after adjustment for baseline renal parameters, duration of renal disease, use of cyclophosphamide and initial treatment response. We concluded that the prevalence of renal disease was similar among SLE patients of different ages of onset. Late onset SLE patients had accrued more renal damage but age did not correlate with renal damage after adjustment for various clinical parameters.

Mycophenolate mofetil for refractory haemolytic anemia in systemic lupus erythematosus

Mycophenolate mofetil (MMF) has been increasingly used in patients with systemic lupus erythematosus (SLE). While most information concentrates on lupus nephritis, its efficacy in nonrenal manifestations of SLE has not been systematically studied. We describe the successful use of MMF in a patient with SLE-related hemolytic anemia that was refractory to cyclophosphamide, pulse methylprednisolone, intravenous immunoglobulin and cyclosporine. The mechanisms of action of MMF are briefly reviewed.

Active disease is independently associated with more severe anxiety rather than depressive symptoms in patients with systemic lupus erythematosus

Objective

The inter-correlation between and co-existence of depression and anxiety may engender inconsistency in addressing the relationship between the severity of depression and disease activity of systemic lupus erythematosus (SLE). We aimed at identifying whether lupus disease activity is independently associated with depression and anxiety in lupus patients.

Methods

Adult lupus patients were assessed for the severity of depressive and anxiety symptoms and lupus disease activity by using the Hospital Anxiety and Depression Scale (HADS) and the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), respectively. Age- and gender-matched healthy controls (HCs) were recruited for comparison. Prevalence and severity of depressive and anxiety symptoms were compared between lupus patients and HCs. Independent relationships between the severity of anxiety (HADS-Anxiety) and depressive (HADS-Depression) symptoms, and SLEDAI were studied with regression models.

Results

In total, 110 lupus patients and 110 HCs were studied. Lupus patients had significantly higher HADS scores than HCs (10.82 ± 6.5 vs 7.34 ± 4.9, p < 0.001). Significantly more lupus patients had anxiety (40.9 vs 21.8%, p = 0.002) and depressive symptoms (15.5 vs 6.4%, p = 0.025) than HCs. Multiple linear regression analyses revealed that SLEDAI (β = 0.160, p = 0.016), calcineurin inhibitor non-use (β = –1.929, p = 0.041) and past cyclophosphamide non-use (β = –1.603, p = 0.039) independently predicted HADS-Anxiety amongst lupus patients even after adjusting for HADS-Depression. Conversely, SLEDAI (β = 0.014, p = 0.834) lost its significant univariate correlation with HADS-Depression after controlling for HADS-Anxiety and other covariates.

Conclusion

Anxiety is more common in lupus patients than in HCs, and its severity is independently associated with more active SLE regardless of the presence or absence of concomitant depression.

Serum tumour necrosis factor-alpha is associated with poor health-related quality of life and depressive symptoms in patients with systemic lupus erythematosus

OBJECTIVES

While patients with systemic lupus erythematosus (SLE) have poorer health-related quality of life (HRQoL) and are more depressed than healthy people, the impact of proinflammatory cytokines, particularly tumour necrosis factor-alpha (TNFα), on these unfavourable psychosocial parameters is unclear. We aim to explore potential relationships between lupus-related proinflammatory cytokines, HRQoL and depressive symptoms in patients with SLE.

METHODS

Patients with SLE and age-matched healthy subjects were assessed for HRQoL and depressive and anxiety symptoms by the Short Form Health Survey-36 (SF-36) and Hospital Anxiety and Depression Scale (HADS) respectively. Using multiplex immunoassay, a panel of serum proinflammatory cytokines including TNFα, interleukin (IL)-1β, IL-6, IL-17, IL-23 and IL-33 were determined and compared between both groups. Independent associations between SF-36, serum proinflammatory cytokine levels and HADS scores were studied by regression models.

RESULTS

In total, 54 patients and 54 healthy controls were studied. Lupus patients had significantly poorer HRQoL (p < 0.001) and were significantly more depressed (p = 0.006) and anxious (p = 0.022) than their healthy counterparts. Amongst the proinflammatory cytokines studied, serum TNFα was significantly higher in lupus patients (p < 0.001). After multivariate adjustment, higher serum TNFα (β = -0.224, p = 0.047) remained significantly associated with lower SF-36, along with smoking (β = -0.253, p = 0.014) and more severe depressive symptoms (β = -0.433, p = 0.002). In healthy subjects, serum TNFα was associated with depressive symptoms but not with SF-36.

CONCLUSIONS

Higher serum TNFα level is independently associated with poorer HRQoL and more severe depressive symptoms in SLE patients. These associations suggest a potential impact of inflammatory response on depressive symptoms and the quality of life in patients with SLE.

Global survey of national tuberculosis drug policies

SETTING

National tuberculosis (TB) programmes (NTPs) in 100 countries.

OBJECTIVES

To evaluate the relationship between the estimated prevalence of multidrug resistance in previously untreated TB cases and policies regarding sales and distribution of TB drugs, particularly rifampicin (RMP).

DESIGN

Questionnaire survey of national TB drug control policies, completed by NTP managers. Results were correlated with recent World Health Organization estimates of prevalence of drug resistance in new cases of TB.

RESULTS

Questionnaires were received from 100 countries, including 88 low- and middle-income countries (LMICs) and 17 of the 22 high-burden countries. Current policies were considered adequate in only 40 of the 88 LMICs (45%). A higher prevalence of multidrug resistance was associated with fewer years of free availability of TB drugs from the NTP (P = 0.02) and more years of availability of RMP from providers or pharmacies outside the NTP (P = 0.02). Eleven of the 20 countries with the highest prevalence of multidrug resistance had inadequate policies governing sales and distribution of TB drugs.

CONCLUSIONS

These findings suggest that policies regarding sales and distribution of TB drugs should receive more emphasis as part of the global strategy to control drug resistance.

Lumbar spine bone mineral density predicts endothelial reactivity in patients with systemic lupus erythematosus

OBJECTIVES

To explore whether endothelial function is related to bone mineral density (BMD) in patients with systemic lupus erythematosus (SLE).

METHODS

Consecutive adult SLE patients and age-, sex-, BMI- and smoking-status-matched healthy controls were studied. Subjects with hypertension, hyperlipidemia, diabetes mellitus, renal impairment, dysthyroidism, history of or treatment for cardiovascular and cerebrovascular disorders, antiphospholipid syndrome, positive antiphospholipid antibodies or bone loss were excluded. Endothelial function was assessed by measuring flow-mediated dilatation (FMD) at the brachial artery and carotid intima-media thickness (IMT) by ultrasound. Lumbar and hip BMD were measured by dual-energy x-ray absorptiometry. Fasting blood samples were assayed for atherogenic index and high sensitivity C-reactive protein (hsCRP). Regression models were constructed to study the relationship between FMD and BMD.

RESULTS

One hundred and ten subjects (55 SLE and 55 matched healthy controls) were studied. While there were no differences between SLE patients and controls in menopausal status, blood pressure, atherogenic index, carotid IMT and BMD, SLE patients had significantly poorer FMD even after adjustment for age, gender, smoking and baseline brachial artery diameter. Also, SLE patients with lumbar osteopenia had significantly lower FMD than those with normal BMD. Multivariate regression revealed that lower FMD was associated with lower lumbar BMD and higher serum hsCRP in SLE patients, but these relationships were absent amongst healthy controls.

CONCLUSIONS

Lumbar vertebral BMD predicted endothelial reactivity in SLE patients without clinically-overt bone loss and atherosclerosis. Thus, early atherosclerotic disease should be considered in lupus patients especially if vertebral bone loss is evident.

The economic burden of systemic lupus erythematosus in Asia: the current state

Systemic lupus erythematosus (SLE) is a chronic systemic inflammatory disorder which imposes considerable negative impact on patients’ function and quality of life, and it appears to entail substantial loss of work productivity and healthcare cost. Although much has been studied regarding the epidemiology, pathogenesis, disease activity, disease damage and pharmacological treatment of SLE, publications on the economic burden of lupus are scarce. As the majority of lupus patients are residing in the Asia Pacific region where many are financially and socially deprived, and, from what we know from the current literature, work disability of lupus patients in Asia is substantial, cost-of-illness studies on SLE are thus particularly relevant in countries around the region. Reliable data from properly conducted prospective SLE cost studies are imperative for policymakers to efficiently distribute healthcare resources, especially in Asia where limited resources are unable to cope with the huge population. In this paper, we review the current state of cost-of-illness research on lupus in Asia and analyze the reasons why such studies are urgently required in the Asia Pacific region.

Noncontact evaluation of articular cartilage degeneration using a novel ultrasound water jet indentation system

We previously reported a noncontact ultrasound water jet indentation system for measuring and mapping tissue mechanical properties. The key idea was to utilize a water jet as an indenter as well as the coupling medium for high-frequency ultrasound. In this paper, the system was employed to assess articular cartilage degeneration, using stiffness ratio as an indicator of the mechanical properties of samples. Both the mechanical and acoustical properties of intact and degenerated bovine patellar articular cartilage (n = 8) were obtained in situ. It was found that the stiffness ratio was reduced by 44 +/- 17% after the articular cartilage was treated by 0.25% trypsin at 37 degrees C for 4 h while no significant difference in thickness was observed between the intact and degenerated samples. A significant decrease of 36 +/- 20% in the peak-to-peak amplitude of ultrasound echoes reflected from the cartilage surface was also found for the cartilage samples treated by trypsin. The results also showed that the stiffness obtained with the new method highly correlated with that measured using a standard mechanical testing protocol. A good reproducibility of the measurements was demonstrated. The present results showed that the ultrasound water jet indentation system may provide a potential tool for the non-destructive evaluation of articular cartilage degeneration by simultaneously obtaining mechanical properties, acoustical properties, and thickness data.

Neuropsychiatric lupus and reversible posterior leucoencephalopathy syndrome: a challenging clinical dilemma

Reversible posterior leucoencephalopathy syndrome (RPLS) has been increasingly recognized and reported in the literature. While the condition has been well described in patients with acute hypertension, pre-eclampsia, eclampsia, post-transplantation and chemotherapy, RPLS has been increasingly identified in patients with autoimmune diseases such as systemic lupus erythematosus (SLE). Though experience in the diagnosis and management of RPLS in patients with SLE is likely accumulating, few have systematically worked out the strategy to distinguish RPLS from neuropsychiatric SLE (NPSLE) and lupus-related complications of the central nervous system (CNS). Prompt recognition of, and differentiation between, these conditions is essential since their clinical presentations substantially overlap and yet their management strategy and subsequent outcomes can be entirely different. Indeed, inappropriate treatment such as augmentation of immunosuppression may be detrimental to patients with RPLS. A high index of suspicion of RPLS, prompt magnetic resonance imaging of the brain, including diffusion imaging, exclusion of CNS infection and metabolic derangement, a comprehensive medication review accompanied by timely and aggressive control of blood pressure and seizure are keys to successful management of RPLS. Such treatment strategy ensures a very high chance of total neurological recovery in lupus patients with RPLS.

Adrenomedullin--a potential disease activity marker and suppressor of nephritis activity in systemic lupus erythematosus

OBJECTIVES

To investigate whether plasma adrenomedullin (AM) level is elevated in lupus nephritis and to examine if plasma AM level is correlated with systemic lupus erythematosus (SLE) disease activity and severity of lupus nephritis after multivariate adjustment.

METHODS

Consecutive SLE patients and healthy volunteers of age >/=16 were recruited from the rheumatology clinics of two hospitals in Hong Kong. SLE patients with nephritis fulfilled the American College of Rheumatology criteria for renal involvement and had percutaneous renal biopsy performed. Subjects were divided into three groups: (i) SLE patients with nephritis, (ii) SLE patients without nephritis and (iii) normal controls. The demographic and clinical variables were compared between these groups of patients and plasma AM level was determined by radioimmunoassay. Factors associated with plasma AM level were explored by regression analysis with adjustment of confounding factors.

RESULTS

Sixty SLE patients (39 with nephritis and 21 without) and 23 normal subjects were studied. The plasma AM level of SLE patients was significantly higher than that of normal controls. SLE patients with nephritis had significantly higher plasma AM level than those without nephritis and normal controls (P<0.001). In regression analysis, proteinuria was negatively associated with plasma AM level (P=0.006) whereas SLE disease activity index was positively associated with plasma AM level after multivariate adjustment (P=0.002).

CONCLUSIONS

Plasma AM is elevated in lupus nephritis, which correlates with lupus disease activity. It is negatively associated with urine protein excretion although it is unrelated to the type of renal pathology per se. Plasma AM may play a role to suppress the activity of lupus nephritis.

Outcome of protein-losing gastroenteropathy in systemic lupus erythematosus treated with prednisolone and azathioprine

OBJECTIVES

To report the efficacy of prednisolone and azathioprine (AZA) in the treatment of systemic lupus erythematosus (SLE)-related protein-losing gastroenteropathy (PLGE).

METHODS

Between 1995 and 2002, 16 consecutive patients with SLE-related PLGE were treated with a regimen consisting of high-dose prednisolone (0.8-1 mg/kg/day for 6 weeks, then tapered to < or =10 mg/day) and AZA (2 mg/kg/day). Protein leakage from the gastrointestinal tract was confirmed by 99mTc-labelled human serum albumin scintigraphy and significant urinary loss of protein was excluded. Clinical response at 6 months of therapy was assessed and patients were followed for relapse of PLGE.

RESULTS

Clinical characteristics of our patients at the time of PLGE were: age 36.2 +/- 8.7 (s.d.) yr; female:male ratio 15 : 1; mean SLE duration 29.6 +/- 65 months. Twelve patients had PLGE as the initial presentation of SLE. Fifteen (94%) patients had concomitant activity in other organs. All patients presented with oedema and eight patients (50%) had non-bloody diarrhoea. The mean serum albumin level was 22.8 +/- 5.7 g/dl. Protein leakage was at the small bowel in 11 (69%) patients and the large bowel in 5 (31%) patients. At 6 months of therapy, 14 (88%) patients had complete clinical response, 1 (6%) patient responded partially and 1 patient (6%) was treatment-refractory. Patients who responded were maintained on low-dose prednisolone (7.8 +/- 6.1 mg/day) and AZA (56.3 +/- 37 mg/day). Over a mean follow-up of 57.5 months, 1 (6%) patient had relapse of PLGE which responded to augmentation of prednisolone dosage. No patients developed alternative gastrointestinal diagnoses. Corticosteroid-induced psychosis, AZA-induced pancytopenia and herpes zoster occurred in three patients.

CONCLUSION

PLGE is an uncommon manifestation of SLE. Treatment with a combination of prednisolone and AZA is effective and well tolerated.

Bone mineral density in postmenopausal Chinese patients with systemic lupus erythematosus

The objective was to study the bone mineral density (BMD) and its clinical determinants in a cohort of postmenopausal patients with systemic lupus erythematosus (SLE). All postmenopausal SLE patients receiving long term glucocorticoids were identified from our medical clinics. Lumbar and femoral BMDs were measured by dual X-ray absorptiometry. Clinical determinants of BMD were studied by simple and multiple linear regression. Variables evaluated were: age, body mass index, parity, duration of menopause, smoking and alcohol drinking, duration of SLE and steroid treatment, cumulative prednisone dose, clinical and serological profile, disease activity, damage index and the use of medications. In total, 34 patients were studied. The mean age was 52.9+/-4.9 years and the median duration of SLE was 75.5 months. The mean duration of menopause was 5.2+/-3.9 years and the daily maintenance dose of prednisone was 4.0+/-2.5 mg/day. At the lumbar spine, 33% of the patients were osteopenic and 48% were osteoporotic. Two patients had thoracic and lumbar vertebral compression fractures. At the nondominant femoral neck, 74% of patients were osteopenic but only 3% was osteoporotic. In a multivariate model, the current or past use of hydroxychloroquine (HCQ) was associated with a higher spinal BMD. The presence of anti-Sm and the absence of anti-Ro were associated with a higher femoral BMD. It was concluded that osteoporosis, especially at the spine, is a common and serious problem in postmenopausal Chinese SLE patients receiving long term glucocorticoid therapy. Active intervention should be considered. The protective role of HCQ has to be confirmed with further studies.

Calcium-independent contraction and sensitization of airway smooth muscle by p21-activated protein kinase

In Triton-skinned phasic ileal smooth muscle, constitutively active recombinant p21-activated kinase (PAK3) has been shown to induce Ca(2+)-independent contraction, which is accompanied by phosphorylation of caldesmon and desmin (Van Eyk JE, Arrell DK, Foster DB, Strauss JD, Heinonen TY, Furmaniak-Kazmierczak E, Cote GP, and Mak AS. J Biol Chem 273: 23433-23439, 1998). In the present study, we investigated whether PAK has a broad impact on smooth muscle in general by testing the hypothesis that PAK induces Ca(2+)-independent contractions and/or Ca(2+) sensitization in tonic airway smooth muscle and that the process is mediated via phosphorylation of caldesmon. In the absence of Ca(2+) (pCa > 9), constitutively active glutathione-S-transferase-murine PAK3 (GST-mPAK3) caused force generation of Triton-skinned canine tracheal smooth muscle (TSM) fibers to approximately 40% of the maximal force generated by Ca(2+) at pCa 4.4. In addition, GST-mPAK3 enhanced Ca(2+) sensitivity of contraction by increasing force generation by 80% at intermediate Ca(2+) concentrations (pCa 6.2), whereas it had no effect at pCa 4.4. Catalytically inactive GST-mPAK3(K297R) had no effect on force production. Using antibody against one of the PAK-phosphorylated sites (Ser(657)) on caldesmon, we showed that a basal level of phosphorylation of caldesmon occurs at this site in skinned TSM and that PAK-induced contraction was accompanied by a significant increase in the level of phosphorylation. Western blot analyses show that PAK1 is the predominant PAK isoform expressed in murine, rat, canine, and porcine TSM. We conclude that PAK causes Ca(2+)-independent contractions and produces Ca(2+) sensitization of skinned phasic and tonic smooth muscle, which involves an incremental increase in caldesmon phosphorylation.

Impact of donor arm skin disinfection on the bacterial contamination rate of platelet concentrates

BACKGROUND AND OBJECTIVES

Despite improved methods for detecting bacterial contamination of blood products, bacterial sepsis remains a significant risk in blood transfusion. This study was undertaken to investigate whether adopting a different skin disinfection protocol could reduce the rate of bacterial contamination of platelet concentrates.

MATERIALS AND METHODS

Two skin disinfection protocols were consecutively used in the routine blood collection setting during two 10-month periods: 0.5% cetrimide/0.05% chlorhexidine solution followed by 70% isopropyl alcohol (first 10-month time-period); and 10% povidone-iodine followed by 70% isopropyl alcohol (second 10-month time-period). The rates of bacterial contamination of platelet concentrates were monitored by using a surveillance programme described previously.

RESULTS

The overall bacterial contamination rate in the first time-period was 0.072%. After introduction of the povidone-iodine and isopropyl alcohol protocol, the bacterial contamination rate decreased to 0.042% (relative risk reduction: -0.42; 95% confidence interval, -0.12 to -0.61, P= 0.009). There were no differences in the types of micro-organisms identified (P = 0.7).

CONCLUSIONS

Skin disinfection by povidone-iodine and isopropyl alcohol is more effective than that by cetrimide/chorhexidine and isopropyl alcohol in reducing venepuncture-associated contamination of platelet concentrates by skin flora. Our data indicate that the disinfection protocol should be used on a routine basis and such implementation should translate into a significant improvement in blood safety to patients receiving platelet transfusion.

Three patients with lead poisoning following use of a Chinese herbal pill

We report on three patients with lead poisoning following use of the Chinese herbal pill Bao ning dan, prepared by the same traditional Chinese medicine practitioner. The patients had varying degrees of exposure to Bao ning dan and different clinical manifestations. Blood lead concentrations did not correlate with clinical severity. Two patients received chelating therapy and blood lead concentrations subsequently rapidly decreased. One patient was managed conservatively and end-organ complications resolved gradually. With increasing use of traditional Chinese medicines, related adverse reactions are expected to become increasingly common. Practitioners of western medicine should remain alert to this possibility. A comprehensive drug review, including the use of herbal medicines, should form a routine part of medical history taking.

G2/M arrest caused by actin disruption is a manifestation of the cell size checkpoint in fission yeast

In budding yeast, actin disruption prevents nuclear division. This has been explained as activation of a morphogenesis checkpoint monitoring the integrity of the actin cytoskeleton. The checkpoint operates through inhibitory tyrosine phosphorylation of Cdc28, the budding yeast Cdc2 homolog. Wild-type Schizosaccharomyces pombe cells also arrest before mitosis after actin depolymerization. Oversized cells, however, enter mitosis uninhibited. We carried out a careful analysis of the kinetics of mitotic initiation after actin disruption in undersized and oversized cells. We show that an inability to reach the mitotic size threshold explains the arrest in smaller cells. Among the regulators that control the level of the inhibitory Cdc2-Tyr15 phosphorylation, the Cdc25 protein tyrosine phosphatase is required to link cell size monitoring to mitotic control. This represents a novel function of the Cdc25 phosphatase. Furthermore, we demonstrate that this cell size-monitoring system fulfills the formal criteria of a cell cycle checkpoint.

Experimental discordant hepatic xenotransplantation in the recipient with liver failure: implications for clinical bridging trials

BACKGROUND

Clinical xenotransplantation might start with bridge-to-bridge trials. Situations where hyperacute rejection is avoided would provide opportunities for the initiation of bridging trials. Patients with liver failure have a diminished capacity to initiate antibody and complement-induced injury of xenogeneic endothelium. Hyperacute rejection of a liver xenograft manifests as a coagulopathy. We examined the ability of a recipient with liver failure to hyperacutely reject a liver xenograft in the dog-to-pig model in the immediate postoperative period.

STUDY DESIGN

Liver failure in pigs was induced with galactosamine. Canine livers were transplanted into pigs with liver failure and into healthy pigs. The postoperative course was monitored for 1 hour for histologic changes in the xenograft, changes in platelet counts, and whole blood clotting with Sonoclot analysis. In vitro assays with pig serum and canine hepatic sinusoidal endothelial cells were used to assess the effect of liver failure on serum cytotoxicity and xenoreactive antibody levels.

RESULTS

All untreated pig recipients of liver xenografts died from a coagulopathy. Recipients with liver failure manifested no signs of coagulopathy, and had minimal change in platelet counts or Sonoclot (Sienco Inc., Morrison, CO) tracings. Liver xenograft biopsies from recipients with liver failure showed no evidence of the tissue injury that characterized the biopsies of control recipients. Serum from pigs was less cytotoxic to the canine hepatic sinusoidal endothelium after induction of liver failure. The xenoreactive antibody levels and repertoire were similar in the pig serum before and after liver failure was induced. CH50 (total complement) levels were diminished in pigs after the induction of liver failure.

CONCLUSIONS

Liver xenotransplantation used in bridging trials in recipients with liver failure might not face the barrier of hyperacute rejection.

Mechanical characterization of regenerated osseous tissue during callotasis and its related biological phenomenon

The mechanical characteristics of the regenerated osseous tissue and osteoblastic activities during callotasis were studied using Chinese mountain goat as the animal model. Open osteotomy of the left tibiae was done in 24 goats. Distraction started 6 days after the operation with the rate of 1 mm per day for 4 weeks. The bone regeneration was monitored with serial X-ray films. The tension generated during distraction was measured with the strain gauges mounted on the distraction apparatus. The osteoblastic activities were monitored by measuring plasma bone specific alkaline phosphatase activity. The results showed that the average lengthening was 22.9 +/- 2.8 mm in each animal. The newly formed osseous tissue becomes stiffer during the course of distraction lengthening. The continuous evolution of the tensile behaviour of the newly formed osseous tissue correlates with the plasma bone specific alkaline phosphatase activities. The radiological appearance of a physis like structure took place at 12 mm lengthening. Its appearance corresponds to the changes in the tensile behaviour as well as the biological activities of the osteoblasts and may serve as a useful radiological marker in monitoring the process of callotasis in clinical practice.

Mitotic separation of daughter cells in the human lymphoma B cell line Daudi involves L-selectin engagement and shedding

BACKGROUND AND OBJECTIVE

A novel role for shedding of the surface molecule L-selectin has been proposed as an adjunctive phenomenon during cell detachment from marrow stroma or vessel endothelium. We wished to examine whether variations in expression of L-selectin on a lymphoma B cell line were linked to shedding.

DESIGN AND METHODS

Mapping of L-selectin expression on the surface of Daudi lymphoma cells was performed by flow cytometry, fluorescence microscopy, and electron microscopy. Levels of shed L-selectin were evaluated by Western blotting of culture supernatants. Evaluation of cell cycle and proliferative activity was performed by flow cytometry.

RESULTS

Large Daudi cells in S+G(2)/M phases were L-selectin positive, whereas small Daudi cells in G(0)/G(1) phase were L-selectin negative. During mitosis, L-selectin was distributed along the cleavage furrow, and gradually lost. Electron microscopy revealed that separating Daudi cells were negative for L-selectin on the entire surface, except minute aggregates of L-selectin within the cleavage furrow. Addition of agents known to interfere with the ligand-binding portion of L-selectin (sulfatides, MoAbs: Lam1.3 and TQ1) results in loss of L-selectin. Removal of L-selectin by digestion with chymotrypsin inhibits Daudi proliferation. The MoAb FMC46 did not interfere with proliferation. Proliferating Daudi cells produced large quantities of shed L-selectin. Inhibition of Daudi proliferation resulted in levels of shed L-selectin below the limit of detection.

INTERPRETATION AND CONCLUSIONS

L-selectin is re-distributed on the cell surface of Daudi cells during the last phase of mitosis, in which plasma membrane invagination occurs between newly formed daughter cells. Shedding of L-selectin is involved in the cytokinesis of Daudi cells.

Endoglin is a component of the transforming growth factor (TGF)-beta receptor complex of human pre-B leukemic cells

Endoglin was first identified on a cell line derived from pre-B acute lymphoblastic leukemia. This 180-kDa homodimeric glycoprotein was then shown to be primarily expressed on endothelial cells and to bind the beta 1 and beta 3 isoforms of TGF-beta with high affinity. We now demonstrate that pre-B leukemic cells express a functional TGF-beta 1 receptor complex. The levels of mRNA for these receptors and for TGF-beta 1 were quantitated by PCR. HOON, G2, and NALM-6 cell lines express similar levels of mRNA for TGF-beta 1 and for TGF-beta receptor I (R-I) and receptor II (R-II). HOON cells express ten times more endoglin than G2 and NALM-6 cells, whereas all three cell lines have low levels of betaglycan relative to other cell types. The receptors were identified by affinity labeling with 125I-labeled TGF-beta 1, chemical cross-linking, and specific immunoprecipitation. Endoglin, R-II, and R-I were co-precipitated by Abs to either endoglin or R-II, indicating that these proteins are forming a receptor complex on leukemic cells; no betaglycan could be immunoprecipitated. The receptor complex is functional, as demonstrated by inhibition of proliferation of HOON cells (80%) and NALM-6 cells (60%) with 25 pM TGF-beta 1. Furthermore, the motility of HOON and NALM-6 cells on immobilized fibronectin, which appears to be alpha 4 beta 1-integrin mediated, was stimulated two- to threefold by TGF-beta 1. These results suggest that active TGF-beta 1 produced in the bone marrow microenvironment might stimulate the motility of normal pre-B cells and the peripheral dissemination of leukemic pre-B cells.

Endoglin is a component of the transforming growth factor (TGF)-beta receptor complex of human pre-B leukemic cells

Endoglin was first identified on a cell line derived from pre-B acute lymphoblastic leukemia. This 180-kDa homodimeric glycoprotein was then shown to be primarily expressed on endothelial cells and to bind the beta 1 and beta 3 isoforms of TGF-beta with high affinity. We now demonstrate that pre-B leukemic cells express a functional TGF-beta 1 receptor complex. The levels of mRNA for these receptors and for TGF-beta 1 were quantitated by PCR. HOON, G2, and NALM-6 cell lines express similar levels of mRNA for TGF-beta 1 and for TGF-beta receptor I (R-I) and receptor II (R-II). HOON cells express ten times more endoglin than G2 and NALM-6 cells, whereas all three cell lines have low levels of betaglycan relative to other cell types. The receptors were identified by affinity labeling with 125I-labeled TGF-beta 1, chemical cross-linking, and specific immunoprecipitation. Endoglin, R-II, and R-I were co-precipitated by Abs to either endoglin or R-II, indicating that these proteins are forming a receptor complex on leukemic cells; no betaglycan could be immunoprecipitated. The receptor complex is functional, as demonstrated by inhibition of proliferation of HOON cells (80%) and NALM-6 cells (60%) with 25 pM TGF-beta 1. Furthermore, the motility of HOON and NALM-6 cells on immobilized fibronectin, which appears to be alpha 4 beta 1-integrin mediated, was stimulated two- to threefold by TGF-beta 1. These results suggest that active TGF-beta 1 produced in the bone marrow microenvironment might stimulate the motility of normal pre-B cells and the peripheral dissemination of leukemic pre-B cells.

Ectopic expression of human and feline CD9 in a human B cell line confers beta 1 integrin-dependent motility on fibronectin and laminin substrates and enhanced tyrosine phosphorylation

Few molecules have been shown to confer cell motility. Although the motility-arresting properties of anti-CD9 monoclonal antibody (mAb) suggest the transmembrane 4 superfamily (TM4SF) member CD9 can induce a motorgenic signal, gene transfection studies have failed to confirm this hypothesis. We report here that ectopic expression of human CD9 (CD9h) and feline CD9 (CD9f) in the CD9-negative, poorly motile, human B cell line Raji dramatically enhances migration across fibronectin- and laminin-coated polycarbonate filters. Migration of Raji/CD9h and Raji/CD9f on either substrate was inhibited by the anti-CD9 mAb 50H.19 and by the anti-beta 1 integrin mAb AP-138. Migration of Raji/CD9h on laminin was potently inhibited by the anti-VLA-6 integrin mAb GoH3 and by the anti-VLA-4 integrin mAb 44H6, whereas migration of Raji/CD9h on fibronectin was inhibited only by mAb 44H6. Since CD9h-transfected Raji cells adhered to fibronectin as effectively as mock transfectants, expression of CD9 enhanced motility, but not adhesion. CD9-enhanced migration was inhibited by the protein tyrosine kinase inhibitor herbimycin A suggesting that tyrosine phosphorylation played a role in the generation of a motorgenic signal. Raji/CD9h transfectants adherent to fibronectin expressed 6-fold higher levels of phosphotyrosine than Raji. Raji/CD9f transfectants also phosphorylated proteins on tyrosine more effectively than Raji including a protein of 110 kDa which was phosphorylated on the motility-inducing substrates laminin and fibronectin, but not on bovine serum albumin. Our results support a role for CD9 in the amplification of a motorgenic signal in B cells involving beta 1 integrins and the activation of protein tyrosine kinases.