Tm Chan

Population differences in SLE susceptibility genes: STAT4 and BLK, but not PXK, are associated with systemic lupus erythematosus in Hong Kong Chinese.

In this study, we compared the association of several newly discovered susceptibility genes for systemic lupus erythematosus (SLE) between populations of European origin and two Asian populations. Using 910 SLE patients and 1440 healthy controls from Chinese living in Hong Kong, and 278 SLE patients and 383 controls in Thailand, we studied association of STAT4, BLK and PXK with the disease. Our data confirmed association of STAT4 (rs7574865, odds ratio (OR) =1.71, P=3.55 × 10−23) and BLK (rs13277113, OR=0.77, P=1.34 × 10−5) with SLE. It was showed that rs7574865 of STAT4 is also linked to hematologic disorders and potentially some other subphenotypes of the disease. More than one genetic variant in STAT4 were found to be associated with the disease independently in our populations (rs7601754, OR=0.59, P=1.39 × 10−9, and P=0.00034 when controlling the effect of rs7574865). With the same set of samples, however, our study did not detect any significant disease association for PXK, a risk factor for populations of European origin (rs6445975, joint P=0.36, OR=1.06, 95% confidence interval: 0.93–1.21). Our study indicates that some of the susceptibility genes for this disease may be population specific.

Association of interleukin-10 promoter polymorphisms with systemic lupus erythematosus.

Several lines of evidence suggest interleukin-10 gene (IL-10) is a candidate gene in susceptibility to systemic lupus erythematosus (SLE). We investigated the association of IL-10 promoter single-nucleotide polymorphisms (SNPs) (−3575T/A, −2849G/A, −2763C/A, −1082A/G, −819T/C and −592A/C) and microsatellites (IL10.R, IL10.G) with SLE in 554 Hong Kong Chinese patients and 708 ethnically matched controls. Six haplotypes (hts) were identified from the SNPs. The genotype distribution of the ht1 (T-C-A-T-A), which is associated with low IL-10 production, was different in patients and controls (P=0.009). The homozygous genotype of non-ht1 was significantly increased in patients (P=0.009, odds ratio (OR)=1.80, 95% CI: 1.15–2.82). The frequency of IL10.G4 of IL10.G was also significantly increased in patients (P=0.017, OR=2.53, 95% CI: 1.18–5.40). We found that the homozygous non-ht1 combined with short allele (CA repeat number ⩽21) of IL10.G has a dose-dependent effect on SLE susceptibility: non-ht1/non-ht1 with homozygous short allele showed a higher OR (OR=4.11, 95% CI: 1.27–13.2, P=0.018) of association with SLE than the genotype of non-ht1/non-ht1 with heterozygous short/long allele (OR=2.98, 95% CI: 1.26–7.07, P=0.013) and homozygous long allele (OR=1.05, 95% CI: 0.62–1.78, P=0.848). The frequency of non-ht1 was significantly increased in patients with serositis (P<0.0001, OR=2.42, 95% CI: 1.55–3.80). In conclusion, the high expression promoter genotype is associated with SLE in Chinese.

Clinical characteristics and outcome of southern Chinese males with systemic lupus erythematosus.

The aims were to study the gender differences in clinical manifestations, disease course and organ damage in systemic lupus erythematosus (SLE). Clinical manifestations, autoantibody profile, relapses and damage scores were obtained from 51 Chinese males with SLE and compared with 201 consecutive female SLE controls. Fifty-one males were identified among 630 SLE patients who attended our clinics, giving a male prevalence of 8% and a female to male ratio of 11.4–1. Both the male SLE patients and the female controls had similar age and SLEDAI score at disease onset. Male SLE patients had less alopecia (P = 0.03), Raynauds phenomenon (P = 0.01) and anti-Ro (P = 0.049) during the course of the disease but none of the differences were statistically significant after correction for multiple observations. The prevalence of major organ involvement in either sex was not different. Both groups of patients had a comparable mean duration of follow-up (104 vs 102 months, P = 0.87). Males had a significantly lower rate of relapses (total No. of flares/patient-year: 0.23 in men vs 0.33 in women, P = 0.04), but the frequency of severe flares (No. of severe flares/patient/year in men 0.08 vs 0.12 in women, P = 0.16) was not significantly different from the females. Male patients with positive anti-Ro had significantly less overall flares than their female counterparts who were anti-Ro positive (0.16 vs 0.34, P = 0.006). However, the use of immunosuppressive agents for disease control in patients of both sexes was similar. 22 (43%) of the males and 78 (39%) of the females had organ damage. A higher percentage of male patients had impairment of renal function (P = 0.006) but the proportion of patients who required dialysis was not different (4% in men vs 2% in females, P = 0.92). There was also a trend of more cardiovascular damage in the males but the difference was not statistically significant (P = 0.09). The mean SLICC/ACR scores were not significantly higher in the males than the females (0.71 vs 0.60, P ‘ 0.47). Males tend to differ from females in clinical manifestations, immunological profile and disease course in SLE. However, there was no gender difference in the involvement of major organs/systems. Males had less overall disease flares than the females but the rate of severe flares was not significantly lower. For patients who were anti-Ro positive, males had significantly less total number of flares/patient-year than their female counterparts. More renal impairment and cardiovascular damage was present in our male lupus patients but the overall damage scores were not significantly higher.

Association of BANK1 and TNFSF4 with systemic lupus erythematosus in Hong Kong Chinese

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease with complex genetic inheritance. Recently, single nucleotide polymorphisms (SNPs) in BANK1 and TNFSF4 have been shown to be associated with SLE in Caucasian populations, but it is not known whether they are also involved in the disease in other ethnic groups. Recent data from our genome-wide association study (GWAS) for 314 SLE cases and 920 controls collected in Hong Kong identified SNPs in and around BANK1 and TNFSF4 to be associated with SLE risk. On the basis of the results of the reported studies and our GWAS, SNPs were selected for further genotyping in 949 SLE patients (overlapping with the 314 cases in our GWAS) and non-overlapping 1042 healthy controls. We confirmed the associations of BANK1 and TNFSF4 with SLE in Chinese (BANK1, rs3733197, odds ratio (OR)=0.84, P=0.021; BANK1, rs17266594, OR=0.61, P=4.67 × 10−9; TNFSF4, rs844648, OR=1.22, P=2.47 × 10−3; TNFSF4, rs2205960, OR=1.30, P=2.41 × 10−4). Another SNP located in intron 1 of BANK1, rs4522865, was separately replicated by Sequenom in 360 cases and 360 controls and was also confirmed to be associated with SLE (OR=0.725, P=2.93 × 10−3). Logistic regression analysis showed that rs3733197 (A383T in ankyrin domain) and rs17266594 (a branch point-site SNP) from BANK1 had independent contributions towards the disease association (P=0.037 and 6.63 × 10−8, respectively). In TNFSF4, rs2205960 was associated with SLE independently from the effect of rs844648 (P=6.26 × 10−3), but not vice versa (P=0.55). These findings suggest that multiple independent genetic variants may be present within the gene locus, which exert their effects on SLE pathogenesis through different mechanisms.

Treatment of membranous lupus nephritis with nephrotic syndrome by sequential immunosuppression

The optimal therapy for pure membranous lupus nephritis (MLN) with nephrotic syndrome remains controversial. While the risk of progressive renal deterioration may be small, persistent heavy proteinuria leads to the complications of oedema, hypoalbuminaemia, hyperlipidaemia, hypercoagulability, and venous thrombosis. We examined prospectively the efficacy and tolerability of a sequential immunosuppressive regimen in a cohort of 20 patients with nephrotic syndrome due to pure MLN (WHO Class Va and Vb). Initial therapy comprised prednisolone (0.8 mg/kg/d p.o.) and cyclophosphamide (2–2.5 mg/kg/d p.o.). Prednisolone dosage was gradually tapered to 10 mg/d at 6 months, when cyclophosphamide was replaced by azathioprine (2 mg/kg/d p.o.) as maintenance therapy. Within 12 months of therapy 11(55%) patients had complete remission (CR), 7(35%) patients achieved partial remission (PR) (proteinuria reduced from 6.2 4.0 to 2.0 1.7 g =24 h, P < 0.01), and 2 patients failed to respond. Improvements in proteinuria and serum albumin level were observed after 3–6 months of treatment. Non-responders had lower baseline serum albumin compared to complete responders. Renal function remained stable during follow-up for 73.5 48.9 months. 8 patients had disease relapse at 47 15 months. Early complications (12 months) included herpes zoster (40%), minor respiratory or urinary tract infections (25%), mild leukopenia (15%), and transient amenorrhea (14.3%). 4 of the 20 patients developed pulmonary tuberculosis during follow-up, at 35 24 months after the diagnosis of MLN. 8 patients had hyperlipidaemia. Haemorrhagic cystitis, permanent amenorrhea, vascular complications, and mortality were not observed. We conclude that this sequential immunosuppressive regimen is effective in 90% of patients with MLN and heavy proteinuria. Prudent consideration of the benefits and potential side-effects is required to determine the optimal management for individual patients.

Angiotensin inhibition or blockade for the treatment of patients with quiescent lupus nephritis and persistent proteinuria.

Angiotensin-converting enzyme inhibitor (ACEI) or angiotensin II receptor blocker (ARB) reduces proteinuria and the rate of renal function deterioration in diabetic nephropathy and other glomerular diseases, but its role in quiescent lupus nephritis has not been established. We conducted a retrospective study to investigate the effects of ACEI/ARB on proteinuria and renal function in patients with persistent proteinuria (>1 g/day) despite resolution of acute lupus nephritis following immunosuppressive treatment. Fourteen out of 92 patients were included. The duration of treatment with ACEI/ARB was 52.1 ± 35.7 months. The levels of proteinuria, serum albumin, serum creatinine, systolic and diastolic blood pressure were 1.10 to 6.90 g/day, 35.8 ± 3.6 g/L, 102.54 ± 34.48 μmol/L, 137.6 ± 10.9 and 81.9 ± 9.2 mmHg at baseline. Proteinuria and serum albumin showed significant sustained improvements after 6 and 24 months of treatment. Comparison of slopes for serial proteinuria, albumin and reciprocal of serum creatinine before and after treatment showed significant improvements in six (43%), eight (57%) and two patients, respectively. At last follow-up proteinuria remained significantly lower (0.36 g/day, P = 0.043) and albumin higher (41.3 ± 2.2 g/L, P = 0.023). Eleven (78.6%) patients had proteinuria improved by >50%, and five had insignificant proteinuria at last follow-up. Systolic blood pressure was significantly reduced from 6 months onwards, but this did not correlate with proteinuria reduction. Diastolic blood pressure, serum creatinine, creatinine clearance, anti-dsDNA, C3 and haemoglobin were not altered. We conclude that ACEI/ARB effectively reduces proteinuria and improves serum albumin in patients with persistent proteinuria despite quiescent lupus nephritis.

Quality of life comparison between corticosteroid-and-mycofenolate mofetil and corticosteroid- and-oral cyclophosphamide in the treatment of severe lupus nephritis

There is accumulating evidence that mycophenolate mofetil (MMF), when combined with corticosteroid, is an effective induction treatment for severe proliferative lupus nephritis and is associated with fewer adverse effects compared to cyclophosphamide (CTX), but the quality of life (QOL) associated with these regimens as perceived by the patient has not been compared. This study included patients who had experienced both treatment regimens, for distinct episodes of diffuse proliferative lupus nephritis. QOL parameters during the first six months of each treatment were assessed through SF36 and WHOQOL questionnaires. Twelve patients and 24 episodes of severe lupus nephritis were studied. CTX-treated and MMF-treated episodes showed comparable baseline characteristics and response rate, with complete remission occurring in 83.3%. MMF treatment was associated with higher numerical scores for all domains across both QOL instruments than CTX. MMF treatment was associated with significantly less fatigue, less impediment of physical and social functioning, and better psychological well being compared to CTX. When each patient served as her/his own control, most patients ascribed higher QOL domain scores to the MMF-treated episode. Seventy-five percent of patients found MMF treatment more acceptable and preferred when compared with CTX, and the complications that most concerned them included Cushingoid features, alopecia, menstrual disturbance and infections. These data showed that MMF-based induction immunosuppression for severe lupus nephritis was associated with better QOL than CTX as perceived by patients, which was most likely attributed to the reduced side-effects during MMF treatment.

Endothelial cell binding by human polyclonal anti‐DNA antibodies: relationship to disease activity and endothelial functional alterations

Polyclonal anti‐dsDNA and anti‐ssDNA antibodies (PoAb) that showed significant binding to human umbilical vein endothelial cells (HUVEC) were isolated from eight patients with systemic lupus erythematosus (SLE). Anti‐dsDNA PoAbs from five patients and anti‐ssDNA PoAbs from seven patients demonstrated enhanced binding to HUVEC during active disease, compared with PoAbs obtained from corresponding patients during remission. Reduction of the DNA content in the PoAb preparations by DNase treatment was associated with enhanced binding to HUVEC in 20 of 32 PoAbs tested, which included 75%‘active disease’ PoAbs, and with reduced binding to HUVEC in three of 32 PoAbs tested, all obtained during remission. Such altered endothelial cell binding was reversed with DNA reconstitution. Binding of the remaining nine PoAbs to HUVEC was not altered by variations in their DNA content. Induced plasma membrane expression of E‐selectin, but reduced expression of vascular cell adhesion molecule‐1 (VCAM‐1) by HUVEC, was observed following incubation of HUVEC with ‘active disease’ PoAbs from three and two of the eight patients, respectively. PoAbs and serum samples from two of the eight patients during active disease induced von Willebrand factor release from HUVEC, which was not observed during remission. We conclude that anti‐DNA antibodies from selected patients with SLE can bind to endothelial cells. Correlation between cellular binding and disease activity suggests that such binding of anti‐DNA antibodies to endothelial cells could be of pathogenic significance. Preliminary data also suggest that the expression of adhesion molecules and haemostatic factor(s) by endothelial cells may be modified following their binding by anti‐DNA antibodies.

Hepatitis C in renal transplant recipients

Sera from 130 renal transplant recipients were tested for antibody to hepatitis C virus (anti-HCV). Anti-HCV was detected in 6.2% of patients: 15.4% of patients who had maintenance hemodialysis (HD) and 2.2% of those who had continuous ambulatory peritoneal dialysis (CAPD) before transplantation (P<0.05). The similarity in prevalence of anti-HCV with patients currently on dialysis and the absence of transfusion during posttransplant follow-up suggest that most patients acquired HC V infection through transfusion during dialysis. The proportion of anti-HCV-positive patients who had one or more episodes of elevation in serum transaminase level was similar to that of hepatitis B surface antigen (HBsAg)-positive patients, 75% vs. 72.2%. However, anti-HCV was only detected in 25% of HBsAg-negative patients who had recurrent elevations in serum transaminase level. It is not clear whether the low prevalence of anti-HCV in these patients is related to the presence of other non-A, non-B hepatitis virus (es) or a decrease in titer of anti-HCV secondary to immunosuppression posttransplantation.

Differential expression of receptors for advanced glycation end-products in peritoneal mesothelial cells exposed to glucose degradation products

Autoclaving peritoneal dialysate fluid (PDF) degrades glucose into glucose degradation products (GDPs) that impair peritoneal mesothelial cell functions. While glycation processes leading to formation of advanced glycation end‐products (AGE) were viewed commonly as being mediated by glucose present in the PDF, recent evidence indicates that certain GDPs are even more powerful inducers of AGE formation than glucose per se. In the present study, we examined the expression and modulation of AGE receptors on human peritoneal mesothelial cells (HPMC) cultured with GDPs, conventional PDF or PDF with low GDP content. HPMC cultured with GDPs differentially modulated AGE receptors (including RAGE, AGE–R1, AGE–R2 and AGE–R3) expression in a dose‐dependent manner. At subtoxic concentrations, GDPs increased RAGE mRNA expression in HPMC. 2‐furaldehyde (FurA), methylglyoxal (M‐Glx) and 3,4‐dideoxy‐glucosone‐3‐Ene (3,4‐DGE) increased the expression of AGE–R1 and RAGE, the receptors that are associated with toxic effects. These three GDPs up‐regulated the AGE synthesis by cultured HPMC. In parallel, these GDPs also increased the expression of vascular endothelial growth factor (VEGF) in HPMC. PDF with lower GDP content exerted less cytotoxic effect than traditional heat‐sterilized PDF. Both PDF preparations up‐regulated the protein expression of RAGE and VEGF. However, the up‐regulation of VEGF in HPMC following 24‐h culture with conventional PDF was higher than values from HPMC cultured with PDF containing low GDP. We have demonstrated, for the first time, that in addition to RAGE, other AGE receptors including AGE–R1, AGE–R2 and AGE–R3 are expressed on HPMC. Different GDPs exert differential regulation on the expression of these receptors on HPMC. The interactions between GDPs and AGE receptors may bear biological relevance to the intraperitoneal homeostasis and membrane integrity.