Pathogenic significance of interleukin-6 in a patient with antiglomerular basement membrane antibody-induced glomerulonephritis with multinucleated giant cells

The Immunobiological Agents for Treatment of Antiglomerular Basement Membrane Disease

Combination therapy with glucocorticoids, cyclophosphamide, and plasmapheresis is recommended as the standard treatment for anti-glomerular basement membrane (anti-GBM) disease, but the prognosis of this disease remains poor. Several immunobiological agents have been administered or are expected to be useful for anti-GBM disease in light of refractory disease or the standard treatments' tolerability. Many data regarding the use of biologic agents for anti-GBM disease have accumulated, verifying the effectiveness and potential of biologic agents as a new treatment option for anti-GBM disease. Tumor necrosis factor (TNF) inhibitors were shown to be useful in animal studies, but these agents have no clinical use and were even shown to induce anti-GBM disease in several cases. Although the efficacy of the TNF-receptor antagonist has been observed in animal models, there are no published case reports of its clinical use. There are also no published reports of animal or clinical studies of anti-B-cell-activating factor, which is a member of the TNF family of agents. Anti-interleukin (IL)-6 antibodies have been demonstrated to have no effect on or to exacerbate nephritis in animal models. Anti-C5 inhibitor was observed to be useful in a few anti-GBM disease cases. Among the several immunobiological agents, only rituximab has been demonstrated to be useful in refractory or poor-tolerance patients or small uncontrolled studies. Rituximab is usually used in combination with steroids and plasma exchange and is used primarily as an alternative to cyclophosphamide, but there is insufficient evidence regarding the efficacy of rituximab for anti-GBM disease, and thus, randomized controlled studies are required.

Deposition of the Membrane Attack Complex in Healthy and Diseased Human Kidneys

The membrane attack complex-also known as C5b-9-is the end-product of the classical, lectin, and alternative complement pathways. It is thought to play an important role in the pathogenesis of various kidney diseases by causing cellular injury and tissue inflammation, resulting in sclerosis and fibrosis. These deleterious effects are, consequently, targeted in the development of novel therapies that inhibit the formation of C5b-9, such as eculizumab. To clarify how C5b-9 contributes to kidney disease and to predict which patients benefit from such therapy, knowledge on deposition of C5b-9 in the kidney is essential. Because immunohistochemical staining of C5b-9 has not been routinely conducted and never been compared across studies, we provide a review of studies on deposition of C5b-9 in healthy and diseased human kidneys. We describe techniques to stain deposits and compare the occurrence of deposits in healthy kidneys and in a wide spectrum of kidney diseases, including hypertensive nephropathy, diabetic nephropathy, membranous nephropathy, IgA nephropathy, lupus nephritis, C3 glomerulopathy, and thrombotic microangiopathies such as the atypical hemolytic uremic syndrome, vasculitis, interstitial nephritis, acute tubular necrosis, kidney tumors, and rejection of kidney transplants. We summarize how these deposits are related with other histological lesions and clinical characteristics. We evaluate the prognostic relevance of these deposits in the light of possible treatment with complement inhibitors.

Procalcitonin is a specific marker for detecting bacterial infection in patients with rheumatoid arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is a chronic inflammatory disease accompanied by many complications, and serious infections are associated with many of the advanced therapeutics used to treat it. We assessed serum procalcitonin (PCT) levels to distinguish bacterial infection from other complications in patients with RA.

METHODS

One hundred eighteen patients experiencing an RA flare, noninfectious complication of RA or its treatment, nonbacterial infection, or bacterial infection were studied. Serum PCT concentrations were determined with a chemiluminescent enzyme immunoassay.

RESULTS

All patients experiencing an RA flare showed negative PCT levels (≤ 0.1 ng/ml; n = 18). The PCT level was higher in the bacterial infection group (25.8% had levels ≥ 0.5 ng/ml) than in the other 3 groups (0.0-4.3% had levels ≥ 0.5 ng/ml) and the difference was significant among groups (p = 0.003). Conversely, no statistically significant difference was observed among the groups with C-reactive protein (CRP) concentration ≥ 0.3 mg/dl (p = 0.513), white blood cell (WBC) count > 8500/mm(3) (p = 0.053), or erythrocyte sedimentation rate (ESR) > 15 mm/h (p = 0.328). The OR of high PCT level (≥ 0.5 ng/ml) for detection of bacterial infection was 19.13 (95% CI 2.44-149.78, p = 0.005). Specificity and positive likelihood ratio of PCT ≥ 0.5 ng/ml were highest (98.2% and 14.33, respectively) for detection of bacterial infection, although the sensitivity was low (25.8%).

CONCLUSION

Serum PCT level is a more specific marker for detection of bacterial infection than either CRP, ESR, or WBC count in patients with RA. High PCT levels (≥ 0.5 ng/ml) strongly suggest bacterial infection. However, PCT < 0.5 ng/ml, even if < 0.2 ng/ml, does not rule out bacterial infection and physicians should treat appropriately.

Giant cell transformation of podocytes: A unique histological feature associated with cystinosis

Fanconi's syndrome is an unusual cause of renal insufficiency in pediatric patients. Infantile cystinosis is one of the identifiable and treatable etiologies of Fanconi's syndrome. Early diagnosis of cystinosis permits institution of specific therapy with cysteamine. A 3-year-old girl presented with failure to thrive, polyuria, and polydipsia. She was found to have renal tubular defect with renal dysfunction and bilateral small contracted kidneys. A renal biopsy revealed extensive giant cell transformation of podocytes in the glomeruli with focal tubular atrophy and dilatation. However, no crystals were identified. Subsequent ophthalmoscopic examination revealed fine cystine crystals in the cornea and a diagnosis of cystinosis causing Fanconi's syndrome was made. Polykaryocytic transformation of visceral epithelial cells is an important diagnostic clue of nephropathic cystinosis and should be carefully looked for in renal biopsy from a child with Fanconi's syndrome and renal insufficiency.

Anti-glomerular basement membrane antibody-induced glomerulonephritis with periglomerular granulomatous reaction and massive renal eosinophilic infiltration

We present a case of a 68-year-old man with anti-glomerular basement membrane (anti-GBM) antibody-induced glomerulonephritis accompanied by periglomerular granulomatous reaction and massive eosinophilic infiltration. Periglomerular granulomatous giant cells were derived from macrophages, shown by positive staining for monoclonal antibody against cluster of differentiation 68. Staining for eosinophil cationic protein indicated that activated eosinophils were involved in the tubulitis, as well as in the glomerular injury. The patient was admitted to the hospital with fever, loss of appetite, edema of the extremities, abnormal urinalysis results, and rapid progressive renal failure. At an examination 8 months before admission, his serum creatinine level (1.0 mg/dL [88.4 micromol/L]) and urinalysis results were normal. On admission, an elevated serum creatinine level (5.1 mg/dL [450.8 micromol/L]) and marked eosinophilia (eosinophils, 5.00 x 10(3)/microL [5.00 x 10(9)/L]; 37.2% of total white blood cell count) were observed. Serum anti-GBM antibody titer was high (43 EU), measured by means of an enzyme-linked immunosorbent assay. No respiratory or ophthalmological abnormalities were seen. Intravenous steroid pulse therapy followed by oral prednisolone (PSL) was effective for reducing the fever, eosinophilia, anti-GBM antibody titer, and C-reactive protein level, but did not improve renal function because renal tissue already was irreversibly damaged. Oral PSL dose was tapered off without relapse. The patient underwent long-term hemodialysis therapy, which dissipated the edema. He was discharged from our hospital 65 days after admission. Three months later, his anti-GBM antibody level was less than 10 EU, and the number of peripheral eosinophils stayed with the normal range.