Nitric oxide in Henoch-Schönlein purpura

Imbalance of interleukin-18 and interleukin-18 binding protein in children with Henoch-Schönlein purpura

The balance between interleukin-18 (IL-18) and its endogenous antagonist, IL-18 binding protein (IL-18BP), was evaluated in children with Henoch-Schönlein purpura (HSP). Plasma IL-18 and IL-18BP levels and peripheral blood mononuclear cell IL-18 mRNA expression were significantly higher in patients with active HSP (n = 30) than in healthy controls (n = 20); IL-18BP mRNA expression was similar in active HSP and controls. Plasma levels and mRNA expression of IL-18 and IL-18BP in patients in remission (n = 19) were similar to those in controls. The ratios of IL-18 / IL-18BP plasma levels and IL-18 / IL-18BP mRNA levels in active HSP were significantly higher than in patients in remission and healthy controls. Thus, adequate IL-18BP to block the proinflammatory activity of IL-18 may not be present in active HSP and regulation of the IL-18 / IL-18BP balance might provide a potential therapeutic strategy.

Kidney is in trouble with mediators

The kidneys receive 20-25 % of cardiac output and play a main role in the control of cardiovascular homeostasis. It is an endocrine organ that regulates and produces many substances, scavenger particles and immune complexes. Cytokines, growth factors, reactive oxygen metabolites, bioactive lipids, proteases, vasoactive substances such as nitric oxide (NO), adrenomedullin (AM), urotensin-II (U-II), have been released in several diseases, and kidney is one of mostly affected organs in body. Some of these mediators act in a paracrine fashion while some act in autocrine. They play important roles in modulating the cardiovascular responses, renal hemodynamics, and probably in mediating the clinical and laboratory manifestations of several renal diseases. These mediators are like "a double edged sword". While small amounts of them mediate many physiological events, little excess may cause the damage to the healthy cells. Many investigators have searched the role(s) of mediators in several diseases. However, the findings are mostly like the model of "chicken and egg", and indistinguishable as to whether they are the causes of, or results of the diseases. We will discuss mainly the possible roles of NO, AM and U-II in children with several renal diseases and summarize what is known, and what must be known about these mediators.

CTLA-4 +49 A/G genotype and HLA-DRB1 polymorphisms in Turkish patients with Henoch-Schönlein purpura

The pathogenesis of Henoch-Schönlein purpura (HSP) remains unknown; however, it is generally considered to be an immune complex-mediated disease. Cytotoxic T lymphocyte-associated protein 4 (CTLA-4) is expressed on activated T cells, and, thus, it is critically involved in the immune response. We aimed to investigate the possible influence of CTLA-4 polymorphisms for susceptibility to HSP and determine if there were associations with human leukocyte antigen (HLA)-DRB1 genotypes. Using polymerase chain reaction-based DNA genotyping, we investigated the polymorphisms located in the genes encoding CTLA-4 in 100 patients with HSP and 156 ethnically matched healthy controls. When CTLA-4 +49 A/G polymorphism of HSP patients and control group was compared, no associations with joint, gastrointestinal or renal manifestations, or susceptibility to HSP, were observed. However, patients with nephrotic proteinuria had higher HLA-DRB1*13 positivity [odds ratio (OR) = 3.76, 95% confidence interval (95%CI) = 1.25-11.23, P = 0.025]. When the patients were stratified according to CTLA-4 polymorphism, a significant association between nephrotic proteinuria patients and carriage of the AG genotype was also found (OR = 15.42, 95%CI = 1.59-148.82, P = 0.008). These results suggested that CTLA-4 +49 A/G polymorphism does not contribute to susceptibility to HSP; however, the presence of CTLA-4 AG genotype and HLA-DRB1*13 could be a risk factor for developing nephrotic-range proteinuria in these patients.

Vasculitis in children

Vasculitis is rare in children, and, apart from HSP and perhaps KD, most practicing pediatricians will never encounter a case. Nonetheless, progress in the diagnosis and treatment of these conditions has afforded most children with vasculitis a reasonably good prognosis. Accordingly, it is important to consider vasculitis as a potential cause of unexplained inflammation, perplexing rashes, or strange combinations of symptoms. Although evaluation and management of suspected vasculitis are difficult in the best of situations, they are impossible if the diagnosis is not considered.

HLA class 1 associations in Henoch Schonlein purpura: increased and decreased frequencies

Henoch Schonlein purpura (HSP) is the most common vasculitis of childhood. Susceptibility to HSP and associated clinical heterogeneity in HSP may be conferred by a number of genetic loci, including the major histocompatibility complex. We aimed to investigate the implications of the human leukocyte antigen (HLA) class 1 alleles in susceptibility to HSP and determine the possible associations with renal, gastrointestinal (GI), and joint manifestations of the disease. 110 children with HSP (66 boys, 44 girls) and 250 unrelated healthy controls were enrolled in the study. The mean age was 8.65 +/- 3.59 years. HSP was diagnosed on the basis of clinical and laboratory data according to the American College of Rheumatology classification. The diagnosis was supported with skin and/or kidney in most of the patients. Clinical and laboratory findings revealed: skin involvement in 110 (100%), joint manifestations in 82 (74.5%), GI symptoms in 58 (52.7%), and hematuria and/or proteinuria in 36 (32.7%) patients. HLA class 1 alleles were identified by DNA amplification, hybridized with specific primer sequences. Comparison of frequencies between patients and controls were made by using the Fisher's exact test. Odds ratio (OR) was used as the measure of association. HLA A2, A11, and B35 antigens showed an increased risk for predisposition to HSP (OR = 1.714, 95%CI = 1.088-2.700, p = 0.020; OR = 2.185, 95%CI = 1.289-3.703, p = 0.003; and OR = 2.292, 95%CI = 1.451-3.619, p = 0.000, respectively), while HLA A1, B49, and B50 antigens revealed decreased risk for predisposition to HSP (OR = 4.739, 95%CI = 1.828-12.345, p = 0.001; OR = 3.268, 95%CI = 0.955-11.236, p = 0.047; and OR = 7.462, 95%CI = 0.975-55.555, p = 0.024, respectively). Considering the renal involvement and severity of proteinuria, there was no association with HLA class 1 alleles. Our results suggest that the increased frequency of HLA A2, A11, and B35 alleles in unselected pediatric HSP patient population and miscarrying of HLA A1, B49, and B50 could be considered as a risk factor for susceptibility to HSP.

Cerebral vasculitis in a child with Henoch–Schönlein purpura and familial Mediterranean fever

In this case report, a 10-year-old girl with Henoch-Schönlein purpura (HSP) with severe central nervous system involvement and also having familial Mediterranean fever (FMF) is presented.

Leptin levels in Henoch–Schönlein purpura

The objective of this paper is to assess the possible role of nitric oxide (NO) and leptin in Henoch-Schönlein purpura (HSP). We investigated the serum leptin and total nitrite levels in 22 children with HSP in the acute phase and after remission and in 20 age- and sex-matched healthy control. Serum leptin levels (nanograms per milliliter; median, min-max) were statistically higher in the acute phase (12.9, 9.1-19.5) than those in the remission phase (6.1, 3.7-10.5, p<0.001) and in the control group (4.9, 3.8-7.5, p<0.001). Also, serum nitrite levels (micromole per liter; median, min-max) were higher in children in the acute phase (45.0, 32.0-60.0) compared to those in remission phase (30.5, 23.0-48.0) and in the control group (29.5, 18.0-38.0) (p<0.001, p<0.001, respectively). There was a positive correlation between serum leptin and total nitrite levels (r=0.65, p<0.001). We have demonstrated that serum leptin and NO levels were increased during the acute phase in children with HSP, and returned to normal levels in remission. We suggest that leptin and NO may have a role in the immunoinflammatory process of HSP, especially in the acute phase. Further studies are needed to clearly establish the roles of leptin and NO in the pathogenesis of HSP.

Pathogénie des vascularites systémiques primitives (II): vascularites ANCA-négatives

The pathogenesis of different types of systemic vasculitis negative for antineutrophil cytoplasm antibodies (ANCA) and involving small or medium-sized vessels is not very well documented. During polyarteritis nodosa (PAN), which is related to hepatitis B virus (HBV) infection, as well as during cryoglobulinemic vasculitides, associated with hepatitis C virus (HCV), and probably during Henoch Schönlein purpura, histological lesions may result from the deposition of immune complexes formed from viral antigens and from antibodies responsible for the activation of the classic complement pathway and for recruitment of polymorphonuclear neutrophils. Two other mechanisms are discussed for other types of ANCA-negative systemic vasculitis: immune complex deposition and sheer stress at arterial bifurcation points. A bacterial superantigen is suspected in Kawasaki disease but remains unproved.

Vasculitis in children

This article provides a general overview of vasculitis, situations in which the diagnosis should be considered, diagnostic methods, and therapeutic considerations. Details and treatments unique to specific vasculitides are also reviewed.

Nitric oxide and glomerulonephritis

Glomerulonephritis is a common clinical condition that is caused by immune-mediated injury to the kidney and is characterized by dysfunction of the glomerular capillary filtration barrier. Nitric oxide (NO), a ubiquitous molecule with many biological functions throughout the body, has been evaluated as an inflammatory mediator in these circumstances. NO may induce glomerular injury directly or may act via stimulation of a host of other inflammatory mediators. A variety of experimental models of glomerulonephritis have been studied including those induced by infusion of antibodies to the Thy1.1 antigen or glomerular basement membrane, Heymann nephritis, and autoimmune nephritis. In virtually all of these cases there is evidence of increased NO production. Excessive production of NO by inducible nitric oxide synthase (iNOS), derived from infiltrating immune cells or resident glomerular cells, nearly always is associated with increased glomerular injury. Interventions that inhibit this enzyme result in less proteinuria and diminished glomerular damage. In contrast, NO derived from endothelial nitric oxide synthase (eNOS) may limit glomerular disease by preserving endothelial cell integrity. There are only a limited number of studies that have evaluated the impact of NO in patients with glomerulonephritis. Although the bulk of evidence supports a role of NO as a pro-inflammatory mediator in glomerulonephritis, additional work is needed to show an association between altered NO production and the severity and outcome of disease in patients with this disease. It is hoped that better understanding of the role of NO in glomerulonephritis will lead to the development of therapies to ameliorate the disease.

Update on childhood vasculitides

PURPOSE OF REVIEW

The purpose of this review is to provide an update on the new developments in pediatric vasculitis.

RECENT FINDINGS

Because most childhood vasculitides are rare, few large systematic studies have been done. Studies of Henoch-Schönlein purpura have focused on pathogenesis and outcome. Genetic associations and molecular changes occurring during Henoch-Schönlein purpura, including cytokines, and endothelial and nitric oxide metabolism are discussed. Risk factors for renal involvement and poor renal outcome are described. Uncontrolled series of treatment protocols for severe Henoch-Schönlein purpura nephritis are mentioned. Several studies have focused on the pathogenesis of other primary vasculitides, especially polyarteritis nodosa. Series describing the clinical manifestations of childhood vasculitis and case reports of uncommon manifestations of vasculitis in children are presented. The efficacy of new therapies, including the use of thalidomide and biologic modifiers, has been shown in individual childhood cases; however, there are no controlled studies of these agents.

SUMMARY

Besides studies of Henoch-Schönlein purpura, advances in pediatric vasculitis are few as a result of the rarity of most vasculitides in childhood. Multicenter collaboration is necessary to substantially increase the scientific base of investigating and treating childhood vasculitis.

Adrenomedullin and total nitrite levels in children with Henoch-Schönlein purpura

Nitric oxide (NO) is synthesized from endothelium and has an important role in the control of vascular tonus. Adrenomedullin (AM) is a potent vasodilator, and cytoprotective peptide is produced not only in adrenal medulla, but also in the vascular smooth muscle and endothelial cells. To investigate the endothelial synthesis of AM and NO, and endothelial injury in Henoch-Schönlein purpura (HSP), we measured their levels in 16 children with HSP, who were evaluated during the acute and remission phases, and compared with 12 healthy controls. Plasma AM levels (pmol/ml) were significantly higher in acute phase children (46.87+/-11.49) than in those in remission (35.59+/-12.39, p<0.01) and controls (30.70+/-9.12, p<0.001). Similarly, plasma total nitrite levels (mumol/l) were higher in acute phase patients (47.50+/-12.30) than in those in remission (35.94+/-10.08, p<0.005) and controls (34.56+/-11.51, p<0.05). Urinary excretion of AM (pmol/mg creatinine) was higher in acute phase patients (53.85+/-23.22) than in remission patients (29.97+/-9.33, p<0.01) and controls (37.43+/-15.78, p<0.05). Patients had increased urinary nitrite excretion (mumol/mg creatinine) in acute phase (2.39+/-1.18) compared to those in remission (1.53+/-0.90, p<0.05) and controls (1.05+/-0.61, p<0.005). There was no significant difference between remission phase and controls in AM and nitrite levels ( p>0.05). This study concluded that AM and NO may have a role in the immunoinflammatory process of HSP, especially in the active stage, although whether this perpetuates, or protects against, further vascular injury is not clear. Further studies are needed to clearly establish the roles of AM and NO in the pathogenesis of HSP.

Henoch-Schonlein purpura

PURPOSE OF REVIEW

The purpose of this review is to educate the reader about the one of the most common vasculitides of childhood: Henoch-Schonlein purpura. Although the disease has been described for over a century, the etiology has yet to be discovered. Adult-onset Henoch-Schonlein purpura is unusual, but through case studies, this review examines some of the common manifestations of this presentation of disease. Long-term outcome studies are still defining how this disease affects a small but significant percentage of patients afflicted with Henoch-Schonlein purpura.

RECENT FINDINGS

This article will summarize recent work in molecular biology and genetics evaluating predisposing factors in the development of Henoch-Schonlein purpura. Further illustrations of the various complications of Henoch-Schonlein purpura will be reviewed. Recent long-term studies of outcomes of patients with renal disease from Henoch-Schonlein purpura will be summarized.

SUMMARY

After reading this review, the clinician will be able to elucidate the manifestations of Henoch-Schonlein purpura, determine appropriate treatment of the disease, and, most importantly, give the patient information about long-term consequences of Henoch-Schonlein purpura.