S. Di Paolo

Expression of platelet-derived growth factor receptors in normal and diseased human kidney. An immunohistochemistry and in situ hybridization study.

We studied the expression of PDGF-alpha and -beta receptors in 10 normal and 40 pathologic human kidneys (five minimal change disease, five membranous nephropathy, 25 IgA nephropathy, five lupus nephritis), by both immunohistochemistry and in situ hybridization techniques. In normal-appearing kidneys, both PDGF-alpha and -beta receptors were expressed at the glomerular and interstitial level, the latter receptor more intensely than the former. The distribution and degree of expression of both receptors in nonproliferative glomerulonephritides were comparable with those found in normal-appearing kidneys. PDGF-beta receptor gene and protein expression were upregulated in proliferative nephritides both at the glomerular and the interstitial level and strictly correlated with the grade of histologic lesions. Finally, PDGF beta receptor expression was observed at a low level in normal-appearing renal vessels, and strikingly increased in injured arteries. Diseased kidneys displayed only a slight increase of PDGF-alpha receptor expression, chiefly at the interstitial level. Noteworthy, a few cases of lupus nephritis showed a moderate increase of PDGF-alpha receptor also at the glomerular level. These data establish PDGF-beta receptor activation as a candidate for driving glomerular and interstitial proliferation and, probably, expansion of extracellular matrix in proliferative glomerulonephritis, while the role of PDGF-alpha receptor activation at the renal level remains to be elucidated.

Novel application of 4D sonography with B-flow imaging and spatio-temporal image correlation (STIC) in the assessment of the anatomy of pulmonary arteries in fetuses with pulmonary atresia and ventricular septal defect

To assess the reliability of two‐dimensional gray‐scale (2D) and color Doppler echocardiography in the study of the size and anatomy of the central pulmonary arteries and of the sources of pulmonary blood flow in a case series of fetuses with pulmonary atresia and ventricular septal defect (PA‐VSD), and to evaluate whether the use of 4D ultrasound with B‐flow imaging and spatio‐temporal image correlation (STIC) can improve prenatal diagnostic accuracy.

Two- and four-dimensional echocardiography with B-flow imaging and spatiotemporal image correlation in prenatal diagnosis of isolated total anomalous pulmonary venous connection.

To explore whether the use of four dimensional (4D) ultrasound examination with B‐flow imaging and spatiotemporal image correlation (STIC) can supply additional information with respect to two‐dimensional (2D) gray‐scale and color Doppler echocardiography in the prenatal characterization of isolated total anomalous pulmonary venous connection (TAPVC).

Pregnancy in renal transplantation: immunologic evaluation of neonates from mothers with transplanted kidney

The occurrence of pregnancy in young female organ transplant recipients may sustain a high risk for prematurity and low rate of malformations in neonates. Therefore, it is necessary to counsel couples who want a child. In case of pregnancy, strict guidelines must be observed. Continuous exposure to CsA in utero seems to impair T-, B- and NK-cell development and function in neonates. This effect is prolonged throughout the first year of life. In addition, low levels of serum immunoglobulins occur at the same time. This leads to suggest a delayed administration of classical vaccinations (after the first 6 months of life) in view of the potential risks of both sub-optimal immunologic responses, and adverse events after the administration of live, attenuated vaccines in infants born from young female organ transplant recipients.

Low-density lipoproteins enhance transforming growth factor-beta 1 (TGF-β1) and monocyte chemotactic protein-1 (MCP-1) expression induced by cyclosporin in human mesangial cells

Cyclosporin (CsA) is widely used in the treatment of renal disease and transplantation, which are often complicated by alterations of lipid metabolism. Both chronic administration of CsA and hyperlipidaemia have been shown to evoke an early macrophage influx and have progressively led to glomerular and interstitial sclerosis. MCP‐1 is the major monocyte chemoattractant secreted by stimulated mesangial cells and TGF‐β1 is a key mediator of fibrogenesis in chronic progressive renal fibrosis. Thus, the combined effect of CsA and low‐density lipoprotein (LDL) on the gene and protein expression of MCP‐1 and TGF‐β1 in cultured human mesangial cells (HMC) was explored. Both agents induced an early and persistent increase of MCP‐1 and TGF‐β1 mRNA levels and protein release. The simultaneous addition of CsA and LDL did not display any additive effect on target gene expression, but it caused a synergistic effect on MCP‐1 and TGF‐β1 protein secretion into culture medium. On the other hand, CsA and LDL had different effects on cell proliferation: the latter increased DNA synthesis, whereas CsA inhibited both spontaneous and mitogen‐stimulated mesangial cell growth. The study concludes that CsA and LDL display an additive effect on TGF‐β1 and MCP‐1 synthesis and release by HMC, thus possibly co‐operating to induce an early macrophage influx and the subsequent mesangial expansion and increased extracellular matrix deposition. However, in contrast they seem to modulate HMC proliferation differently, which is a further critical event intimately involved in the development of glomerulosclerosis.

A study on glucose metabolism in a small cohort of children and adolescents with kidney transplant

Post-transplant diabetes mellitus (PTDM) and impaired glucose tolerance are now considered among the major adverse events following organ transplantation. The present study was aimed at investigating the regulation of glucose metabolism in pediatric recipients of a kidney transplant (KT), receiving tacrolimus or cyclosporine A-based immunosuppression. Twelve subjects, eight males and four females, aged 12.1±3.8 yr, and with a mean time from KT of 45.6 months were enrolled in the study. All patients had a basal evaluation of fasting glucose (GF), fasting insulin (IF), C-peptide and glycated hemoglobin (HbA1c) levels. They then underwent oral glucose tolerance test (OGTT), with measurement of blood glucose and insulin concentration. Two children had impaired GF, associated with supernormal HbA1c levels, one patient showed impaired glucose tolerance, none had PTDM. Peripheral insulin resistance, as measured by quantitative insulin sensitivity check index (QUICKI) and homeostasis model assessment estimate of insulin sensitivity (HOMA-IR) index, was enhanced in 3 patients. Subsequently, GF significantly increased with time from transplant (p=0.01), while fasting C-peptide and the area under the curve of insulin correlated with creatinine clearance. In conclusion, our results, although generated in a small sample size, would suggest that long-term follow-up of children receiving a KT should extend to explore the response to oral glucose load and at least the basal measure of insulin response.

Angiotensin converting enzyme gene polymorphism in renal transplant patients with IgA nephropathy: relationship with graft function and prevalence of hypertension

SEVERAL LINES of evidence suggest a role for renin– angiotensin system (RAS) in the development and progression of chronic allograft injury. Plasma renin higher activity has been described in patients with progressive worsening of kidney graft function 2 and has been implicated in the pathogenesis of post–transplant hypertension, an important risk factor for graft damage. Serum and tissue levels of angiotensin–converting enzyme (ACE), the key enzyme for the generation of angiotensin II, the biologically active products of RAS, are now known to be under genetic control. Thus, individuals displaying a deletion (D) in intron 16 of the ACE gene have higher humoral and tissue activity of the enzyme than subjects who are homozygous for the insertion (I) allele. Moreover, ACE I/D polymorphism has been shown to be associated with the progression to chronic renal failure in patients with diabetic nephropathy and in those with IgA nephropathy. The aim of the present study was to determine the relationship between the ACE genotype and renal allograft function and the prevalence of hypertension in a group of patients undergoing kidney transplantation for terminal renal insufficiency due to IgA nephropathy (IgAN).

Extreme insulin resistance due to anti-insulin receptor antibodies: a direct demonstration of autoantibody secretion by peripheral lymphocytes

A 59-year-old woman with systemic lupus erythematosus was found to have marked hyperglycemia, extreme insulin resistance and abnormally high plasma immunoreactive insulin. Her circulating erythrocytes displayed a dramatic decrease of 125I-labeled insulin binding. Both the whole serum and purified IgG fraction strongly inhibited the binding of radiolabeled insulin to control erythrocytes. These results suggested, although indirectly, the existence of antibodies to insulin receptors in the serum of the patient. To directly investigate this issue, we used an enzyme-linked solid-phase immunoassay which allows the detection and enumeration of lymphocytes secreting antibodies towards insulin receptors. Peroxidase-conjugated anti-human immunoglobulin is used to reveal the binding of antibodies to insulin receptor-coated dishes. We demonstrated that the patients mononuclear cells, when briefly incubated in Petri dishes with partially purified insulin receptor, were able to secrete immunoglobulins of G class specifically directed to the antigen. Moreover, only a fraction of the whole population of anti-insulin receptor antibodies was directed towards the insulin binding region of the receptor, seemingly corresponding to the auto-antibodies detected with conventional binding-inhibition assay.