A case of renal sarcoidosis with complement activation via the lectin pathway.

A 57-year-old woman with pulmonary sarcoidosis was admitted to the hospital because of an elevation of serum creatinine and blood urea nitrogen. On admission, the laboratory data suggested interstitial nephritis without proteinuria and hematuria, whereas a renal biopsy showed granulomatous interstitial nephritis and mild mesangial proliferative glomerulonephritis. Immunoglobulin and C1q deposits were negative, but mannose-binding lectin, C3, C4d, and C5b-9 deposits were marked in the glomerular mesangial areas. The lectin pathway of complement activation may have contributed to the development of glomerular injury in this patient. DNA of Propionibacterium acnes , which is now strongly suspected as the pathogen of sarcoidosis, was detected in the patient's glomerular mesangial cells; tubular epithelial cells, which were involved in granulomatous inflammation; and mononuclear cells in epithelioid granulomas by in situ hybridization. These findings may add new insights to the pathogenesis of renal sarcoidosis, including its relation to infection, because mannose-binding lectin plays a crucial role in the host defense against various pathogens. From this case of renal sarcoidosis, it is hypothesized that P acnes may be involved in pathogenesis of granulomatous interstitial nephritis and that it plays a role in glomerular complement activation via the lectin pathway.

A case of primary immunoglobulin light chain amyloidosis with a delayed appearance of Bence Jones protein in urine.

We report here a case of a 58-year-old man who had nephrotic syndrome and immunoglobulin light chain (AL) amyloidosis. This patient underwent a renal biopsy to confirm the diagnosis. Treatment with permanganate before Congo red staining showed systemic secondary amyloidosis (AA) fibrils, which were sensitive to permanganate oxidation. Although this patient was initially diagnosed as having AA amyloidosis, he did not have any chronic inflammatory disease and/or malignancy. The level of amyloid A protein (7.9 microg/mL) in sera was within the normal range (0-8.0 microg/mL). Therefore, we performed an immunostaining of the precursor protein (amino terminus of constant region: kappa and lambda light chains, and AA protein) using duodenal biopsy specimens for a precise diagnosis. Immunostaining was positive for the amino terminus of constant region of the lambda light chain, and negative for the amino terminus of constant region of the kappa light chain and AA protein. No plasma cell proliferation in the bone marrow was observed. We finally diagnosed this patient as having primary AL amyloidosis. It appears that a pathological diagnosis must be performed by immunostaining the precursor proteins with the permanganate digestion technique in tissue of patients with amyloidosis. There were no abnormalities in serum and urine immunoelectrophoresis at the time of renal biopsy in this patient. During the follow-up period, after discharge, Bence Jones protein appeared in the urine, but not in the serum. It is necessary to observe patients with primary AL amyloidosis carefully to determine if they their condition will progress to multiple myeloma.

Levels of urinary matrix metalloproteinase-9 (MMP-9) and renal injuries in patients with type 2 diabetic nephropathy.

To determine correlations among the levels of urinary MMP-9 and type-IV collagen, hyperglycemia, urinary protein excretion, and renal injuries in patients with type 2 diabetic nephropathy, we measured levels of urinary MMP-9 and protein, blood urea nitrogen (BUN), serum creatinine (s-Cr), fasting plasma glucose (FPG), and glycohemoglobin A1c (HbA1c) in 47 diabetic patients and 14 healthy adults. Urinary type-IV collagen was also measured in 28 diabetic patients and seven healthy adults. Patients with diabetic nephropathy were divided into two groups: 1). patients with normoalbuminuria or microalbuminuria (0-299 mg/g.Cr; n=27), and 2). patients with macroalbuminuria (>300 mg/g.Cr; n=20). The mean level of urinary MMP-9 in group 2 was significantly higher than those in healthy adults (P<0.05), and the levels of urinary MMP-9 in patients with diabetic nephropathy increased in accordance with the clinical stage of the disease. The levels of urinary MMP-9 tended to be correlated with HbA1c in these patients, but the correlation was not statistically significant. The mean level of urinary type-IV collagen in group 2 of patients with diabetic nephropathy was significantly higher than that in group 1 and healthy adults. Levels of urinary type-IV collagen in patients with diabetic nephropathy also increased in accordance with the clinical stage of the disease. The results suggest that measurements of urinary MMP-9, as well as urinary type-IV collagen, may be useful for evaluating the degree of renal injuries in patients with type 2 diabetic nephropathy, especially in the early stage.