Clinical predictors of self-limited urinalysis abnormality in childhood Henoch-Schönlein purpura nephritis

Expression of Acid-Sensing Ion Channels in Renal Tubular Epithelial Cells and Their Role in Patients with Henoch-Schönlein Purpura Nephritis

Background

Acid-sensing ion channels (ASICs) are ligand-gated cation channels activated by extracellular protons. However, the role of ASICs in kidney diseases remains uncertain. This study investigated ASICs expression in kidney tissues and their role in the development of Henoch-Schönlein purpura nephritis (HSPN).

Material/Methods

The expression of ASIC subunits was examined by immunochemical techniques in the kidney tissue from HSPN patients. Acid-induced ASICs expression in cultured renal tubular epithelial cells was determined by quantitative RT-PCR analysis. The expression of K7 and K18 protein in renal tubular epithelial cells was used to evaluate acid-induced cell injury. In addition, we observed the effect of blocking ASICs on acid-induced cell injury to assess the role of ASICs in renal tubular epithelial cell injury.

Results

The results showed that ASIC1, ASIC2, and ASIC3 proteins were obviously expressed in renal tubular cells from HSPN patients. ASIC1 expression and 24-h urine protein level were higher in the pathological grade ISKD III group than in the ISKD II group. ASIC1, ASIC2, and ASIC3 mRNA, and K7 and K18 protein expression in cultured renal tubular epithelial cells were increased when exposed to pH 6.5. K7 and K18 protein expression was closely related to ASIC1 expression, and ASICs blockers reduced K7 and K18 protein expression in tubular epithelial cells.

Conclusions

These findings suggest ASICs are most highly expressed in renal tubular cells of HSPN patients, which is closely related to renal tubular injury. ASICs might be involved in the development of HSPN.

Potential of Serum and Urinary Matrix Metalloproteinase-9 Levels for the Early Detection of Renal Involvement in Children With Henoch-Schönlein Purpura

Background

Matrix metalloproteinase-9 (MMP-9) is an enzyme implicated in the pathogenesis of renal diseases. Renal involvement is the principal cause of morbidity and mortality in children with Henoch-Schönlein purpura (HSP).

Objectives

The aim of this study was to evaluate whether serum and urinary MMP-9 levels are associated with renal involvement in HSP

Patients and Methods

We evaluated 40 children with HSP (patient group) and 27 healthy volunteer children (control group). The patient group was divided into two subgroups based on the presence or absence of nephritis. Nephritis was defined as the existence of hematuria and/or proteinuria. All anthropometric data, physical examination findings, blood pressure, and laboratory parameters were recorded. The serum and urine samples were analyzed to determine the MMP-9 levels three days after the initial phase of the disease.

Results

The mean age was 7.65 ± 3.41 (range 2 - 16) years in the patient group and 9.52 ± 3.91 (range 2 - 16) years in the control group. Henoch-Schonlein purpura nephritis (HSPN) was identified in eight patients. There was no significant difference in the serum MMP-9 levels between the HSPN subgroup and the controls (P > 0.05). However, there were significant differences in the urinary MMP-9 levels between the HSP subgroup and the control group (P < 0.05), with the urinary MMP-9 levels being significantly higher in patients in the HSP subgroup (P = 0.001). Further, the urinary MMP-9 levels were significantly higher in the patients with nephritis than in the patients without nephritis (P = 0.001) and the controls (P = 0.001). The optimal cut-off point (sensitivity; specificity) of the urinary MMP-9 level for the diagnosis of HSPN was 94.7 pg/mL.

Conclusions

The levels of MMP-9 in the urine were remarkably high in patients with HSPN. This non-invasive marker may therefore be an important indicator for the early diagnosis of nephritis in children with HSP.

Periumbilical purpura prior to gastrointestinal involvement in Henoch-Schönlein purpura

Henoch-Schönlein purpura (HSP) is a systemic vasculitis involving the skin, joints, gastrointestinal tract, and kidneys. While HSP is traditionally considered a disease of children, it also occurs in adults. In both populations, acute gastrointestinal complications and chronic renal involvement are major predictors of mortality. While it has been previously demonstrated that truncal lesions in HSP are associated with underlying renal involvement, a significant proportion of cases with gastrointestinal involvement also have associated truncal lesions. It is unclear at this time whether or not the association of truncal involvement with visceral disease is related to an increased burden of circulating immune complexes or a more specific mechanism. We describe a report of periumbilical purpura antecedent to gastrointestinal involvement in an adult with HSP.

Gastrointestinal manifestations of Henoch-Schonlein Purpura

Henoch-Schonlein Purpura (HSP) is the most common systemic vasculitis in childhood. The diagnostic criteria include palpable purpura with at least one other manifestation -- abdominal pain, IgA deposition, arthritis or arthralgia, or renal involvement. Immune complex deposits result in necrosis of the wall of small- and medium-sized arteries with infiltration of tissue by neutrophils and deposition of nuclear fragments, a process called leukocytoclastic vasculitis (LCV). It is often associated with infections, medications, or tumors. It may coexist with or mimic Crohn's disease. Periumbilical and epigastric pain worsens with meals, from bowel angina. Bleeding is usually occult or, less commonly, associated with melena. Intussusception, the most common surgical complication, is usually ileo-ileo or ileo-colic. Perforations, usually ileal, may occur spontaneously or be associated with intussusception. Ultrasound, recommended as the first diagnostic test, and CT scans may show intussusception and asymmetric bowel wall thickening mainly involving the jejunum and ileum. There are a range of endoscopic findings including gastritis, duodenitis, ulceration, and purpura, with the second portion of the duodenum characteristically being involved more than the bulb. Intestinal biopsies show IgA deposition and LCV in the submucosal vessels. Superficial biopsies may show inflammation, ulceration, edema, hemorrhage, and vascular congestion, presumably due to vasculitis-induced mucosal ischemia. The efficacy of corticosteroids in preventing severe complications or relapses is controversial. The majority of patients, however, improve spontaneously.