Defective activation of the MAPK/ERK pathway, leading to PARP1 and DNMT1 dysregulation, is a common defect in IgA nephropathy and Henoch-Schönlein purpura.

Studies on IgA nephropathy (IgAN) have identified, through GWAS, linkage analysis, and pathway scanning, molecular defects in familial and sporadic IgAN patients. In our previous study, we identified a novel variant in the SPRY2 gene that segregates with the disease in one large family. The functional characterization of this variant led us to discover that the MAPK/ERK pathway was defective not only in this family, but also in two sporadic IgAN patients wild type for SPRY2. In the present study, we have deepened the molecular analysis of the MAPK/ERK pathway and extended our evaluation to a larger cohort of sporadic patients and to one additional family. We found that the ERK pathway is defective in IgAN patients and in patients affected by another IgA-mediated disorder, Henoch-Schönlein purpura (HSP). Furthermore, we found that two other proteins, PARP1 and DNMT1, respectively involved in DNA repair and in antibody class switching and methylation maintenance duties, were critically downregulated in IgAN and HSP patients. This study opens up the possibility that defective ERK activation, in some patients, leads to PARP1 and DNMT1 downregulation suggesting that IgAN could be the consequence of a dysregulated epigenetic maintenance leading to the upregulation of several genes. In particular, PARP1 could be used as a potential biomarker for the disease.

Association between RAS gene polymorphisms (ACE I/D, AGT M235T) and Henoch-Schönlein purpura in a Turkish population.

Henoch-Schönlein purpura (HSP) is a small-vessel vasculitis of autoimmune hypersensitivity, and renin-angiotensin system (RAS) regulates vascular homeostasis and inflammation with activation of cytokine release. Thus, we aimed to investigate the association between HSP and ACE I/D and AGT M235T polymorphisms. Genotyping was determined by allele specific PCR and PCR-RFLP. We obtained a significant difference in genotype distribution (p=0.003) and allele frequencies (p<0.001) of ACE I/D polymorphism between patients and controls, while no significant association was detected in genotype distribution (p> 0.05) and allele frequencies (p> 0.05) of the AGT M235T polymorphism. Risk assessment showed significant risk for HSP in the subjects both with the ID + DD genotype (p=0.019, OR: 2.288, 95% CI: 1.136-4.609) and D allele (OR: D vs. I: 2.0528, 95% CI: 1.3632-3.0912, p=0.001) while no significant risk was obtained for HSP in the subjects both with the MT + TT genotype (p=0.312, OR: 1.3905, 95% T vs. M: 1.065, 95% CI: 0.7326-2.6391) and T allele (OR: patients were stratified by the presence of certain systemic complications of HSP, no significant association was detected with ACE I/D, and AGT M235T polymorphisms. Our findings suggest that ACE I/D polymorphism is significantly associated with HSP susceptibility.

Methylenetetrahydrofolate reductase C677T polymorphism in patients with Henoch-Schönlein purpura.

AIM: Associations between several vascular diseases such as Kawasaki disease, venous and arterial thromboembolism, cardiovascular disease, diabetic nephropathy, focal segmental glomerulosclerosis and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism have been reported. This is a clinical study designed to investigate the possible effects of MTHFR C677T polymorphism on the development of Henoch-Schönlein purpura (HSP). METHODS: Forty-one patients with HSP (25 male/16 female) with a mean age of 7.8 ± 2.9 years were included in the study. The control group consisted of 50 healthy children. MTHFR genotypes were determined by polymerase chain reaction and by Hindf I restriction enzyme analysis and subsequent 3% agarose gel electrophoresis techniques. RESULTS: No significant differences were observed in the distribution of MTHFR genotypes or allele frequencies in the HSP cases versus controls. Plasma homocysteine levels and vitamin B(12) levels were almost comparable in the HSP patients and control group without a significant difference. Folic acid levels were within normal limits in the HSP cases and the control group, HSP patients' levels being significantly higher than the control group. No significant relationship was present with the MTHFR genotype and plasma homocysteine, vitamin B(12) and folic acid levels in HSP patients. CONCLUSION: No association with MTHFR gene polymorphism and homocysteine plasma levels could be found in patients with HSP. The results of this study indicate that other mechanisms should be operative in the development of HSP.

Differential glomerular immunoexpression of matrix metalloproteinases MMP-2 and MMP-9 in idiopathic IgA nephropathy and Schoenlein-Henoch nephritis.

Both idiopathic IgA nephropathy (IgAN) and Schoenlein-Henoch nephritis (SHN) are characterized by cell proliferation and abnormal extracellular matrix (ECM) remodeling by mesangial cells leading to fibrosis, sclerosis and end-stage renal disease. Matrix metalloproteinases MMP-2 and MMP-9 are reported as the most important proteolytic enzymes involved in remodeling of ECM. Therefore, the aim of the present study was to determine glomerular immunoexpression of MMP-2 and MMP-9 in IgAN and SHN. Another purpose of this study was to examine the relationship between expression of MMPs and mesangial cells, a-smooth muscle actin (alpha-SMA) staining, and monocytes/macrophages. Fifteen patients with idiopathic IgAN and 12 with SHN were examined by percutaneous renal biopsy. Glomerular staining intensity of MMP-2 and MMP-9 was recorded semiquantitatively, whereas mesangial cells, glomerular alpha-SMA staining and glomerular CD 68+ cells were assessed quantitatively using computer image analysis system. Our study revealed that the mean values of glomerular immunoexpression of MMP-2, mesangial cells, alpha-SMA staining and glomerular CD 68+ cells were in SHN patients significantly increased as compared to IgAN cases whereas glomerular staining for MMP-9 did not differ in these groups. Moreover, a glomerular staining of MMP-2 was significantly positively correlated with mesangial cells as well as glomerular alpha-SMA staining in both SHN and IgAN. A positive significant correlation between glomerular MMP-2 staining and glomerular CD68+ cells was noted only in SHN group. The correlations of glomerular MMP-9 and these parameters were weak and not significant. In conclusion, our results confirm increased glomerular staining of MMP-2 but not MMP-9 in SHN patients. A suggestion that augmented mesangial cells proliferation in these cases depends on MMP-2, alpha-SMA and monocytes/macrophages needs further investigations including double staining study.

Transcriptional expression and gelatinolytic activity of matrix metalloproteinases in Henoch-Schonlein purpura.

AIM: Accelerated extracellular matrix breakdown caused by the increased activity of matrix metalloproteinases (MMPs) has been implicated in several rheumatological disorders and systemic vasculitides, especially Takayasu's arteritis and Kawasaki disease. Therefore, the aim of the present study was to investigate the potential role of MMPs in Henoch-Schonlein purpura (HSP), an acute type of systemic vasculitis in children. METHODS: We studied the activity of MMP-2 and MMP-9 in the sera using gelatin zymography and the transcriptional expression in peripheral blood mononuclear cells using semi-quantitative RT-PCR in 20 patients with HSP in acute and convalescent phase and in 20 healthy children, who were siblings of the subjects with same age group. RESULTS: All 20 children with HSP showed increased levels of serum activity of MMP-2 and MMP-9 in acute phase as compared with their convalescent phase [MMP-2 (p > 0.05); MMP-9 (p > 0.05)] and their control counterparts [MMP-2 (p < 0.001); MMP-9 (p < 0.001)]. Similarly, transcriptional expression of MMPs was found to be higher in the acute phase of HSP than in convalescent phase [MMP-2 (p < 0.05); MMP-9 (p < 0.001)] and in their healthy controls [MMP-2 (p < 0.001); MMP-9 (p < 0.01)]. CONCLUSION: The presence of excessive transcriptional expression and gelatinolytic activity of MMPs may be downstream to the actual aetiopathogenetic factors.

Effect of paraoxonase 1 gene polymorphisms on clinical course of Henoch-Schönlein purpura.

BACKGROUND: Henoch-Schönlein purpura (HSP) is a systemic vasculitis; its pathogenesis is still unknown. Oxidative stress may play a role in the pathogenesis of HSP. Paraoxonase1 (PON1) is an antioxidant enzyme. Two polymorphisms have been defined in the coding region of the PON1 gene, Q/R192 and L/M55. In the present study, we aimed to investigate the effect of PON1 gene polymorphisms on the course and renal involvement of HSP in Turkish children. METHOD: Forty-six patients with HSP were compared with 34 healthy children regarding the distribution of PON1 polymorphisms. RESULTS: PON1 Q/R192 genotype distribution was 58.6% QQ, 32.6% QR and 8.8% RR in the HSP group and 14.3% QQ, 50% QR and 35.7% RR in the control group. The frequency of QQ genotype was higher in the HSP group, and the presence of QQ genotype increased the risk by 3.42-fold for developing HSP (p=0.000, Fisher exact test; odds ratio [OR] = 2.048; 95% confidence interval [95% CI], 1.396-3.00). PON1 L/M55 genotype distribution was 50% LL, 43.5% LM and 6.5% MM in the HSP group and 48% LL, 26% LM and 26% MM in the control group. The frequency of MM genotype was lower in the HSP group, and the presence of MM genotype decreased the risk by 7.38-fold for developing HSP (p=0.009, Fisher exact test; OR=7.380, 95% CI, 1.474-36.953). CONCLUSION: PON1 polymorphisms may contribute to the pathogenesis and course of HSP, but we suggest that further investigations with larger patient groups are required to confirm our results.

[Relationship between integrin-linked kinase expression and renal glomerular damage in children with Henoch-Schnlein purpura nephritis].

OBJECTIVE: Recent studies have shown that integrin linked kinase (ILK) plays an important role in the pathogenesis and development of some kidney diseases. This study aimed to investigate the relationship between ILK and renal glomerular damage in children with Henoch schonlein purpura nephritis (HSPN). METHODS: One hundred and eighty eight HSPN children (aged 3 to 17 years) were assigned to five groups according to the classification of the International Study of Kidney Disease in Children (ISKDC): grade < or = IIa (n = 62), grade IIb (n = 42), grade IIIa (n = 29), grade IIIb (n = 40) and grade > or = IV (n = 15). Fifteen children with basement membrane nephropathy served as the control group. ILK expression on glomeruli was ascertained by immunohistochemical staining. The relationships of ILK expression on glomeruli with glomerular histopathologic lesions and urinary protein excretions were examined. RESULTS: The positive areas of ILK expression on glomeruli in the control, grade < or = IIa, grade IIb, grade IIIa, grade IIIb and grade > or = IV groups were (3.35 + or - 1.01)%, (4.88 + or - 1.13)%, (9.64 + or - 1.36)%, (11.27 + or - 1.68)%, (17.42 + or -3.0)% and (20.62 + or - 2.32%), respectively. There were significant differences in the ILK expression between groups (p<0.01). ILK expression on glomeruli increased with increased urinary protein excretions. There were significant differences in the ILK expression in children with different urinary protein excretions (p<0.01). CONCLUSIONS: ILK might be involved in the process of renal glomerular histopathologic damage and the production of proteinuria in children with HSPN.

Antioxidant enzyme activities, lipid peroxidation, and total antioxidant status in children with Henoch-Schönlein purpura.

The aim of this study was to assess the role of oxidative stress in the pathogenesis of Henoch-Schönlein purpura (HSP) vasculitis. The activities of catalase (CAT), arylesterase (ARYL), and paraoxonase (PON) as antioxidant enzymes and serum malondialdehyde (MDA) level as an indicator of lipid peroxidation, together with total antioxidant status (TAS), were measured in 29 children with HSP (mean age 9.3 +/- 2.7 years), both at the onset of the disease and at the remission period and in matched controls. Active-stage HSP had significantly higher MDA level (15.5 +/- 7.3 vs 7.8 +/- 3.9 nmol/l, respectively, P < 0.001) and lower TAS (524 +/- 122 vs 699 +/- 122 mumol Trolox Equiv/l, P < 0.001), PON (97 +/- 47 vs 136 +/- 95 U/l, P = 0.042), ARYL (158 +/- 39 vs 212 +/- 52 U/l, P < 0.001), and CAT (50 +/- 27 vs 69 +/- 20 U/l, P = 0.002) activities compared with the control subjects. Although CAT (P > 0.05) and PON (P > 0.05) activities were found to be similar between active and remission stages of HSP, the active stage of the disease had significantly lower ARYL (P = 0.011) and TAS (P = 0.006) and higher MDA (P < 0.001) values compared with remission period. Significant positive correlations were found between CAT and MDA (r = 0.433, P = 0.019) and between CAT and C-reactive protein (r = 0.386, P = 0.035) in the active stage of HSP. No significant differences were detected in oxidant/antioxidant parameters between patients with or without renal, gastrointestinal, or joint involvement (P > 0.05). Increased oxidative stress and lipid peroxidation may play important roles in the pathogenesis of HSP vasculitis. Antioxidant therapeutic interventions in long-lasting vasculitis and risk of atherosclerosis secondary to increased oxidant stress remain to be investigated.

Plasma levels of matrix metalloproteinase-9 in Henoch-Schönlein purpura.

OBJECTIVE: To investigate the potential role of matrix metalloproteinase-9 (MMP-9) in Henoch-Schönlein purpura (HSP), an acute type of systemic vasculitis in children. METHODS: In this study, 24 children with HSP and ten healthy children (HC) were enrolled from February 2003 to July 2004. Blood samples were obtained from all the children. The total levels of MMP-9 in the plasma were detected by enzyme-linked immunosorbent assay (ELISA). The second blood samples were obtained from eight of the 24 HSP patients in the convalescent phase. MMP-9 of circulating white blood cells was detected by immunocytochemistry. RESULTS: Plasma MMP-9 levels in the acute phase of HSP (249.75 ng/mL) were significantly higher than in HC (191.00 ng/mL) (p = 0.034). Immunocytochemistry showed that MMP-9 was positive in the circulating white blood cells. The MMP-9 levels in the convalescent phases were lower than in the acute phase in six cases, but increased in the other two cases, and one of these two cases had recurrence of purpuric rashes in the lower extremities for 3 months. CONCLUSION: MMP-9 plays an important role in the vascular destruction of HSP, and circulating white blood cells may be a source of the MMP-9 secreted into the circulation.

Angiotensin-converting enzyme gene insertion/deletion polymorphism in children with Henoch-Schonlein purpua nephritis.

This study investigated the relationship between angiotensin-converting enzyme (ACE) gene insertion/deletion polymorphism and the occurrence, severity, prognosis of HSPN. The polymorphism of ACE gene in 103 HSPN cases and 100 healthy children was studied by using the polymerase chain reactions (PCR). Its relation to the clinical manifestation, pathological classification and prognosis of HSPN was analyzed accordingly. The results showed that: (1) there was a significantly higher frequency for DD genotype in HSPN children (P<0.01); (2) DD genotype was more frequently seen in HSPN children with gross hematuria and massive proteinuria (P<0.05), while DI genotype was more common in HSPN children group with renal insufficiency (P<0.05); (3) although mesangial proliferative lesion was most frequently observed in 21 biopsied HSPN children, and DD genotype frequency was still higher in children with severe pathology (Class III IV); (4) II genotype was significantly frequent in HSPN children with complete remission in the follow-up of 32 HSPN children. It was concluded that the deletion allele of ACE gene might play a role, at least to some extent, in the occurrence, deterioration and progression in juvenile HSPN.

Erythrocyte superoxide dismutase activity and plasma malondialdehyde levels in children with Henoch Schönlein purpura.

Reactive oxygen molecules (ROM) have been suggested to contribute to many pathological conditions including vasculitides and renal diseases. In the present study we measured the activity of superoxide dismutase (SOD) as an antioxidant enzyme in red blood cells and the level of malondialdehyde (MDA), which is a product and an indicator of lipid peroxidation, in the plasma of 16 children (7M, 9F) with Henoch Schönlein purpura (HSP) at the onset of the disease (SOD 1 and MDA 1) and at the remission period (SOD 2 and MDA 2). The results were compared with the results of 17 healthy children studied as a control group. There was no significant difference for SOD activities between the patients in each period and the control group (p > 0.05). There was a statistically significant difference between MDA 1 and MDA 2 levels (p < 0.01), each of which were also significantly different from the MDA levels of control group (p < 0.001 and p < 0.01, respectively). The effect of ROMs on different clinical conditions of HSP was also examined and lipid peroxidation was found to be increased more in patients with renal involvement. It is concluded that oxidant stress especially lipid peroxidation plays an important role in the pathogenesis of HSP and in development of renal injury.

A case of anaphylactoid purpura with multiple blister formation: possible pathophysiological role of gelatinase (MMP-9).

A 10-year-old Japanese male with multiple blister formation and palpable purpura in the course of anaphylactoid purpura is described. Histologically, the lesions showed leukocytoclastic vasculitis in the upper dermis with subepidermal clefts. Blister fluid showed matrix metalloproteinase (MMP) 2 and MMP-9 gelantinolytic activities using zymography. These enzymatic reactions, especially that involving MMP-9 derived from polymorphonuclear leukocytes, might play an important role in the pathophysiology of this condition.

Deletion polymorphism of the angiotensin converting enzyme gene predicts persistent proteinuria in Henoch-Schönlein purpura nephritis.

OBJECTIVE: To study the influence of deletion/insertion polymorphism in the 16th intron of the angiotensin converting enzyme (ACE) gene on clinical manifestations of Henoch-Schönlein purpura nephritis. STUDY DESIGN: Cross sectional study. ACE gene polymorphism was determined in patients (4-15 years old at onset) with Henoch-Schönlein purpura nephritis (n = 40) and compared with that in patients with IgA nephropathy (n = 79). MAIN OUTCOME MEASURES: ACE genotypes, systemic blood pressures, urine protein excretion rate, haematuria, creatinine clearance, serum ACE activities. RESULTS: The initial clinical manifestations of both Henoch-Schönlein purpura nephritis and IgA nephropathy were no different among homozygotes for insertion (II) and deletion (DD), and heterozygotes (ID) for the ACE gene. In patients with Henoch-Schönlein purpura nephritis, the incidence of moderate to heavy proteinuria at four and eight years after onset was more than five times higher in the DD genotype than in the II or ID genotypes. No such trend was seen in patients with IgA nephropathy. The number of patients with Henoch-Schönlein purpura nephritis in whom proteinuria resolved at four and eight years after onset was significantly lower in the DD genotype compared with the II genotype, whereas no differences were detected among the three different genotypes in patients with IgA nephropathy. Plasma ACE activities in patients with the DD genotype were significantly higher than in those with non-DD genotypes. CONCLUSIONS: The ACE DD genotype predicts persistent proteinuria in Henoch-Schönlein purpura nephritis. The proteinuria might be related to a defective angiotensin system which is genetically determined by the D/I polymorphism.