Seiji Nagamachi

Significance of glomerular activation of the alternative pathway and lectin pathway in lupus nephritis

The objective of the present study was to elucidate the association between glomerular complement depositions belonging to the alternative (AP) and lectin (LP) pathways, and clinical findings of lupus nephritis (LN). Immunofluorescence (IF) was performed on 17 LN patients using antibodies against factor B, factor H, properdin, mannose-binding lectin (MBL) and L-ficolin. Compared with factor B/factor H negative patients (n = 9), positive patients (n = 8) showed longer duration of LN (p < 0.05) and more severe interstitial fibrosis (p < 0.05). Eleven patients had properdin deposition in glomeruli, and in three of them, with a duration of LN of less than 1 month, factor B was undetectable. Compared with properdin negative patients (n = 6), positive patients (n = 11) showed significantly higher urinary protein excretion (p < 0.01). MBL/L-ficolin positive patients (n = 11) also had significantly higher urinary protein excretion (p < 0.05) compared with negative patients (n = 6). An independent association was found between glomerular deposition of properdin and that of MBL/L-ficolin (p < 0.01) in addition to factor B/factor H. Traces of glomerular activation of AP and LP reflected the clinical status of LN. It appears that glomerular deposition of each complement component, especially properdin, may be an index of the histological activity of LN.

Fluctuation of serum C3 levels reflects disease activity and metabolic background in patients with IgA nephropathy.

BACKGROUND We focused on the fluctuations of serum C3 levels throughout the clinical course of patients and investigated the relationship between these fluctuations and clinical findings. METHODS IgA nephropathy patients (n = 122) were enrolled in the present study. Serum C3 and other clinical markers were compared at the time of renal biopsy and at last follow-up (6.67 ± 2.07 years). Patients were divided into 3 groups based on serum C3 levels: Group I with first C3 levels below the mean -1 SD, which turned into an increase at last observation; group II with first C3 levels more than the mean +1 SD, which turned into a decrease at last observation; and group III, with first C3 levels more than the mean +1 SD, which turned into an increase at last observation. First and last levels of clinical markers were compared among the 3 groups. RESULTS Serum C3 levels of the patients whose renal symptoms, including hematuria, proteinuria and estimated glomerular filtration rate (eGFR), were improved, were significantly increased at last observation (p<0.05, p<0.01, p<0.01, respectively). Age, total cholesterol and triglyceride levels in group III were significantly higher than those in group I. Group II showed a significant reduction of urinary protein. Groups I and II maintained renal function, but group III showed a significant deterioration of renal function. CONCLUSIONS The levels and fluctuations of serum C3 might reflect the disease activity and metabolic alteration in patients with IgA nephropathy.

Leukocytosis and high hematocrit levels during abdominal attacks of hereditary angioedema

BackgroundThe diagnosis of hereditary angioedema (HAE) is often delayed due to the low awareness of this condition. In patients with undiagnosed HAE, abdominal symptoms often create the risk of unnecessary surgical operation and/or drug therapy. To explore the cause of misdiagnosis, we compared the laboratory findings of HAE patients under normal conditions with those during abdominal attacks.MethodsPatient medical histories were analyzed and laboratory data at the first consultation with no symptoms and no medication were compared with those at visits to the emergency department during severe attacks.ResultsFourteen HAE patients were enrolled. Initial HAE symptoms occurred at 20.2 ± 9.4 years of age. The correct diagnosis of HAE was made 22.7 ± 14.2 years after the initial symptoms. A common site of angioedema was the extremities. Half of the patients experienced a life-threatening laryngeal attack and/or severe abdominal pain. In the patients with severe abdominal pain, significant leukocytosis with neutrophilia along with increased levels of hematocrit were observed while levels of C-reactive protein (CRP) remained low. All severe attacks were alleviated with an infusion of C1-inhibitor concentrate.ConclusionsConsideration of the likelihood of a HAE attack is important when patients present with acute abdominal pain and leukocytosis without elevation of CRP.

Properdin has an ascendancy over factor H regulation in complement-mediated renal tubular damage

BackgroundUrinary (U)-complement components have been detected in patients with proteinuric renal diseases, and complement activation via the alternative pathway (AP) is believed to play a role in renal tubular damage. The present study aimed to examine the regulation of complement AP activation in patients with renal tubular damage by focusing on the balance between properdin (P) and factor H (fH).MethodsIn the in vivo studies, U concentrations of P, fH and membrane attack complex (MAC) were measured in patients with renal diseases using an enzyme-linked immunosorbent assay (ELISA), and their relationships with the clinical data were evaluated. In the in vitro studies, human proximal tubular epithelial cells (PTECs) were incubated with normal human serum (NHS), P-depleted serum (PDS), purified P and/or fH. Changes in cell morphology and phenotype were assessed by microscopy, real-time polymerase chain reaction (PCR), immunostaining and a cell viability assay.ResultsThe U-P, fH and MAC concentrations were significantly higher in patients with renal disease than in normal controls and correlated with the U-protein and tubular damage markers. Furthermore, multivariate analysis revealed a relationship between P levels and tubular damage markers. There were no significant changes in morphology and mRNA expression in the AP components (P, fH, fB, C3, C5 and C9) after the addition of up to 25% NHS. Dose-dependent depositions of P or fH were observed after the addition of P or fH on PTECs. Depositions of P were not inhibited by fH in a mixture of a fixed concentration of P and a variable concentration of fH, and vice versa. Preincubation with the fixed concentration of P before the addition of NHS or PDS increased the depositions of P, C3 and MAC compared with incubation with intact NHS or intact PDS only; the depositions of C3 and MAC showed a serum-dependent trend. Preincubation with P before NHS addition significantly suppressed cell viability without causing morphological changes.ConclusionsIn the pathogenesis of renal tubular damage, P can directly bind to PTECs and may accelerate AP activation by surpassing fH regulation.

Clinical and Laboratory Characteristics That Differentiate Hereditary Angioedema in 72 Patients with Angioedema

BACKGROUND Hereditary angioedema (HAE) is a rare but life-threatening condition that results from mutations in C1-inhibitor (C1-INH). Since distinguishing HAE from other causes of angioedema (AE) is a critical problem in emergencies, the objective of the present study was to clarify the differences between HAE and other forms of AE. METHODS Seventy-two patients with AE were enrolled in this study. The medical history and laboratory data of patients with HAE at the first visit were compared to those with other types of AE. RESULTS Subjects included 23 patients with HAE, 33 with mast cell-mediated AE, 5 with drug-induced AE and 11 with idiopathic AE. The average age of HAE onset (19.5 ± 8.0 years old) was significantly lower than in other groups. A family history of AE was noted in 82.6% of HAE patients, which was significantly higher than other groups. Swelling affecting the extremities and gastrointestinal (GI) tract was observed in the majority (60 to 80%) of HAE patients. Life threatening laryngeal edema was observed in 30.4% of HAE patients. In 95.6% of HAE patients serum levels of C4 were less than the lower limit of the normal range. In our subjects, the sensitivity and specificity of low C4 for HAE were 95.6% and 93.8%, respectively. CONCLUSIONS Early onset of AE, positive family history, recurrent AE in the extremities and GI tract, and suffocation are distinctive characteristics of HAE. A low serum level of C4 is a useful marker for making a differential diagnosis of HAE.

Immune Complex-Mediated Complement Activation in a Patient with IgG4-Related Tubulointerstitial Nephritis

A 59-year-old man was diagnosed with IgG4-related tubulointerstitial nephritis. His symptoms as well as laboratory and imaging findings were improved after initiation of steroid therapy. Serologically, he showed hypocomplementemia (C3 23 mg/dl, C4 <2 mg/dl, CH50 <7 U/ml) with high levels of IgG (IgG4 1,970 mg/dl) and immune complexes (C1q assay 8.1 µg/ml) and a low level of C1q (<2.0 mg/dl). Histologically, he also showed linear depositions of IgG, IgM, C3, C4d, C1q, membrane attack complex and all IgG subclasses (IgG1, IgG2, IgG3 and IgG4) along the tubular basement membrane, as well as granular depositions of these components in the renal interstitium. However, mannose-binding lectin and L-ficolin were not detected in these tissues. Homogeneous electron-dense deposits were observed by electron microscopy in the tubular basement membrane. It appears that the immune complexes might activate the classical pathway of the complement in both blood and local tissues in a patient with IgG4-related tubulointerstitial nephritis.

Impact of Body Mass Index on Progression of IgA Nephropathy Among Japanese Patients.

The impact of being overweight remains unclear in Asian populations that tend to be lean. The objective of this study is to clarify the impact of body mass index (BMI) and metabolic factors on the prognosis of Japanese patients with IgA nephropathy (IgAN).

Occurrence of Reversible Posterior Leukoencephalopathy Syndrome in a Continuous Ambulatory Peritoneal Dialysis Patient

A 25 year-old man presented with reversible posterior leukoencephalopathy syndrome manifesting as seizure, loss of consciousness and severe hypertension. He had contracted end stage kidney disease due to Alport syndrome and was treated with continuous ambulatory peritoneal dialysis for one year. Because his residual renal function was declining, he had refractory hypertension for several months before admission. On the admission, brain T-2 intensified magnetic resonance imaging revealed hyperintensive changes that were restricted to the cortex and the subcortical white matter of the parietal lobe, temporal lobe and posterior lobe. His clinical symptoms were improved by appropriate control of blood pressure using antihypertensive drugs and fluid depletion by continuous hemodiafiltration. Previous hyperintensive lesions disappeared in brain magnetic resonance imaging. He was transferred to maintenance hemodialysis three times weekly and discharged. One month later, he had a seizure attack again because of refractory hypertension which may be derived from low compliance with sodium and water restriction. We report here a reversible posterior leukoencephalopathy syndrome patient on peritoneal dialysis with severe hypertension and volume overload.