Guido Martina

Monoclonal Gammopathy and Glomerulonephritis With Organized Microtubular Deposits

We report a case with IgG-kappa monoclonal gammopathy of unidentified significance (MGUS) and glomerulonephritis (GN) with organized microtubular deposits on electron microscopy (EM). Light microscopy (LM) examination showed exudative features and moderate extracapillary proliferation. An acute nephritic syndrome with a rapidly progressive renal failure was clinically manifest at the onset and during each relapse. The patient was treated with methylprednisolone pulses followed by oral prednisone, cyclophosphamide, plasmapheresis, and maintenance courses of chemotherapy. The response to treatment was good, with a temporary improvement of renal function and control of the downhill course over a 3-year follow-up.

Single kidney function: Effect of acute protein and water loading on microalbuminuria

The hyperfiltration induced by an acute response to an oral protein and water load was investigated to ascertain whether it can modify the urinary albumin excretion (UAE) in the microalbuminuric range by further increasing the glomerular filter permeability. To this end, six patients with a single kidney selected as having microalbuminuria on a regular diet without the clinical or laboratory data of overt renal disease and eight healthy subjects received a short-term protein and water load (150 g of meat-derived protein and 1 liter of water). In patients with one kidney, mean basal UAE values were significantly higher than in control subjects (p less than 0.006), whereas endogenous creatinine clearance values were only slightly lower (p greater than 0.05). One hour after the protein and water load, an abrupt increase in microalbuminuria levels was found in patients with one kidney and mean UAE values were significantly higher than in control subjects (p less than 0.002), whereas mean creatinine clearance values were significantly lower in patients than in control subjects (p less than 0.01). High UAE (p less than 0.002) and low creatinine clearance (p less than 0.002) values were maintained over the following four hours in patients with one kidney. These data suggest that in the single kidney with reduced renal functional reserve, an oral protein and water load magnifies the pre-existing loss of glomerular permselective properties due to chronic hyperfiltration as manifested by a further increase in microalbuminuria.

Intradialytic Cytokine Gene Expression

Along with the numerous technological improvements in molecular biology, polymerase chain reaction, which permits analysis of sequences of a very small amount of biological material, enables evaluation of hemodialysis-induced gene transcription of inflammatory cytokines. Blood samples drawn from 22 hemodialysis patients, treated with cellulose- derived or synthetic membranes, were collected at 0 and 15 min of hemodialysis. Total RNA, purified from mononuclear cells, was reverse transcribed and cDNA amplified by polymerase chain reaction primed with specific oligomers in order to determine tumor necrosis factor α (TNFα), interleukin (IL) 1β and IL6 gene expression. Plasma samples were collected at 0 and 180 min for detection of mature cytokines by enzyme immunoassay with plates pre-coated with monoclonal antibodies to TNFα, IL1β and IL6. A significant increase in TNFα mRNA was detected at 15 min of hemodialysis in 12 of 22 patients: 5 of 9 treated with cuprophan; 3 of 3 with cellulose triacetate; 3 of 5 with polysulfone, and only 1 of 5 treated with polymethylmethacrylate membranes. A parallel increase in IL1β or IL6 mRNA was detected, and significant relationships were found between TNFα and IL1β (p < 0.001), and IL1β and IL6 gene expression (p < 0.05). Increased levels of mature TNFα and IL1β molecules in plasma were detected in the majority of patients showing an increased cytokine gene expression. However, the absolute amount of cytokine mRNA transcription at 15 min did not predict the levels of mature molecules reached in plasma at 180 min. Cytokine mRNA transcription is quite common at the beginning of a dialysis run. Possibly due to intracellular degradation of critical sequences of cytokine mRNA, gene expression does not necessarily imply translation into mature protein. It is suggested that mechanisms related to cell-to-cell interaction, which may possibly involve procytokine biology, are needed to drive phenomena of cytokine activation to clinical effectiveness.

Association Between Elevated Prolactin Levels and Circulating Erythroid Precursors in Dialyzed Patients

The prolactin (PRL) receptor (R), a member of the cytokine hemopoietin receptor superfamily, has been shown to activate early differentiation steps along the erythroid pathway. In particular PRL, a product of bone marrow stroma, induces functional erythropoietin (EPO)-R on CD34+ hemopoietic progenitors. In this study, expression of EPO-R mRNA and responsiveness to EPO were assessed on enriched hemopoietic progenitor cells (HPC) from seven hyperprolactinemic and three normoprolactinemic patients and two normal subjects. Expression of EPO-R mRNA by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was found in HPC of four out of seven hyperprolactinemic patients but not in normoprolactinemic patients or normal donors. Development of EPO-dependent Colony Forming Unit-Erythroid (CFU-E) colonies in semi-solid medium was observed only in hyperprolactinemic patients (six out of seven). A much higher number of CFU-E colonies was observed in the four patients with a positive EPO-R message. We conclude from these data that abnormally high levels of PRL may increase the number of EPO-responsive hemopoietic precursors in vivo as they do in vitro. Since hyperprolactinemia associates in these patients with depressed EPO production, it may be regarded as a compensatory mechanism for the reduced availability of the hemopoietic factor.

WHAT IS THE ROLE OF SENSITIZATION IN UREMIC PRURITUS ? : AN ALLERGOLOGIC STUDY

Patch tests were carried out to evaluate the presence of a sensitization to some components of dialytic circuits in 17 uremic patients complaining of pruritus of unknown origin. Fragments of different dialyzer membranes, of tubing sets, of dialyzer membranes recently resterilized with ethylene oxide and the International Contact Dermatitis Research Group standard series substances were tested. Neither patients nor healthy subjects reacted positively to patch tests, which leads us to question the role of contact allergy in the determination of uremic pruritus.

Failure to Relate Mononuclear Phagocyte System Function to HLA-A, B, C, DR, DQ Antigens in Membranous Nephropathy

Nineteen patients with idiopathic membranous nephropathy were typed for HLA pattern and analyzed for the Fc receptor function of splenic macrophages by detecting in vivo the clearance of IgG-sensitized 51Cr-labelled autologous erythrocytes. Seven out of 19 patients were found to have a macrophage dysfunction. This defect was not related to any HLA-A, B, C, DR, DQ antigen tested nor to the levels of IgG-containing immune complexes, as detected by a Clq solid phase test, nor to the magnitude of proteinuria. Since HLA-B8 and HLA-DR3 antigens were significantly more frequent in patients than in the control group, the factors that may impair the macrophage system in individuals predisposed to this nephropathy are discussed.

Low-protein vegetarian diet with alpha-chetoanalogues prior to pre-emptive pancreas-kidney transplantation.

BACKGROUND Pre-emptive pancreas-kidney transplantation is increasingly considered the best therapy for irreversible chronic kidney disease (CKD) in type 1 diabetics. However, the best approach in the wait for transplantation has not yet been defined. AIM To evaluate our experience with a low-protein (0.6 g/kg/day) vegetarian diet supplemented with alpha-chetoanalogues in type 1 diabetic patients in the wait for pancreas-kidney transplantation. METHODS Prospective study. Information on the progression of renal disease, compliance, metabolic control, reasons for choice and for drop-out were recorded prospectively; the data for the subset of patients who underwent the diet while awaiting a pancreas-kidney graft are analysed in this report. RESULTS From November 1998 to April 2004, 9 type 1 diabetic patients, wait-listed or performing tests for wait-listing for pancreas-kidney transplantation, started the diet. All of them were followed by nephrologists and diabetologists, in the context of integrated care. There were 4 males and 5 females; median age 38 years (range 27.9-45.5); median diabetes duration 23.8 years (range 16.6-33.1), 8/9 with widespread organ damage; median creatinine at the start of the diet: 3.2 mg/dl (1.2-7.2); 4 patients followed the diet to transplantation, 2 are presently on the diet, 2 dropped out and started dialysis after a few months, 1 started dialysis (rescue treatment). The nutritional status remained stable, glycemia control improved in 4 patients in the short term and in 2 in the long term, no hyperkalemia, acidosis or other relevant side effect was recorded. Proteinuria decreased in 5 cases, in 3 from the nephrotic range. Albumin levels remained stable; the progression rate was a loss of 0.47 ml/min of creatinine clearance per month (ranging from an increase of 0.06 to a decrease of 2.4 ml/min) during the diet period (estimated by the Cockroft-Gault formula). CONCLUSIONS Low-protein supplemented vegetarian diets may be a useful tool to slow CKD progression whilst awaiting pancreas-kidney transplantation.

Classic and Perinuclear Anti-Neutrophil Cytoplasm Antibodies and Antimyeloperoxidase Antibodies in Rapidly Progressive Glomerulonephritis

Classic anti-neutrophil cytoplasm antibodies (cANCA), perinuclear ANCA (pANCA) and antibodies directed against myeloperoxidase (MPO-Ab) were evaluated in 25 patients with either idiopathic or secondary rapidly progressive glomerulonephritis (RPGN). While cANCA were found almost exclusively in Wegeners granulomatosis, pANCA were detectable in several disorders, including microscopic polyarteritis (mPA), but also idiopathic RPGN. MPO-Ab were frequently found in sera from patients with all types of idiopathic but not of secondary RPGN. These results support the hypothesis that some cases of RPGN are early or limited forms of systematic vasculitis. We then looked for the presence of IgA-ANCA in Henoch-Schoenlein purpura (HSP): we found IgA-ANCA with immunoenzymatic assay but not with immunofluorescence in HSP, in primary IgA-GN and in membranous GN as well, thus suggesting the poor specificity of this type of ANCA. The possible pathologic implications of ANCA were examined in vitro. Serum samples from several patients with ANCA were assessed for their capacity to enhance chemiluminescence generation from resting or PMA-stimulated macrophages. Sera from RPGN and mPA patients displaying anti-MPO activity induced granulocytes to enhance the production of oxygen free radicals, thus suggesting a phlogistic effect of MPO-Ab positive sera.

Fc-receptor function of the mononuclear phagocyte system in glomerulonephritis secondary to some multisystem diseases.

The Fc-receptor function of the mononuclear phagocyte system was examined in 30 patients affected by multisystem diseases with glomerular involvement by measuring the immune clearance of IgG-sensitized autologous red blood cells in vivo and the immune phagocytosis of monocytes in vitro. Patients studied in the phase of clinically active renal disease showed a significantly reduced Fc-receptor function by both in vivo (p less than 0.001) and in vitro (p = 0.003) assays, as compared to those studied during an inactive phase. Though the nature of the defect remains uncertain, it appears to be related to the active phase of the renal disease as also confirmed by the analysis of individual cases studied longitudinally.

In vitro study of Fc-receptor function in autoimmune diseases

A simple test for studying in vitro Fc-receptor function of mononuclear phagocytes is described. Immune phagocytosis is analyzed as a dynamic phenomenon by using nearly pure suspensions of monocytes incubated for diverse times with autologous erythrocytes sensitized with highly purified IgG. In a series of normal volunteers and patients with vasculitis a strict correlation has been found between this in vitro assay and the measure of splenic clearance of IgG-coated red blood cells (RBC), the classical approach for studying in vivo macrophage Fc-receptor function by using sodium chromate 51Cr as tag. The use of this in vitro assay appears to be valuable mainly in cases requiring repeated measurements of Fc-receptor function for monitoring the course of disease or the effects of therapy.