SUMMARYThere is evidence that nephritis is dominated by a Th1 immune response in systemic lupus erythematosus. Since IL-18 promotes polarization of the immune response toward Th1, we investigated the role of this cytokine in lupus nephritis (LN). A total of 133 lupus patients and 44 healthy subjects were enrolled. Demographic and clinical characteristics with renal biopsy data were recorded. IL-18 along with IFN-g and IL-4, two prototypical of Th1 and Th2 cytokines, were measured in serum by ELISA. Peripheral blood lymphocytes were analysed by flow cytometry for IFN-g and IL-4. IL-18 expression was determined by immunohistochemistry in 13 renal biopsy specimens from patients with LN and 2 controls. Serum IL-18 was higher in lupus patients than in controls. Levels of IL-18 correlated with urinary microalbumin and were increased in patients with LN when compared to those without LN. IL-18 expression was also increased within the glomeruli of nephritic patients and was primarily detected within the mesangial matrix and in infiltrating mononuclear cells. Measurement of IFN-g and IL-4 in either sera or peripheral blood lymphocytes showed high IFN-g along with low IL-4 expression in LN patients compared to patients without nephritis. A positive correlation between serum IL-18 and IFNg levels was found. IL-18 may play a prominent role in the pathogenesis of LN by promoting a cytokine imbalance towards a Th1 immune response. Measurement of IL-18 may be helpful for the early identification of lupus patients with LN and may help gauge the response to treatment in patients with active LN undergoing treatment.

The kidney is one of the major sites of EGF production and there it seems to play several biological functions, such as modulation of cell growth, renal repair following injury, regulation of cellular metabolism and glomerular haemodinamics. The present study was first aimed at localizing EGF and its receptor (R) in normal human kidney by immunohistochemical and in situ hybridization techniques. Then, the distribution of the growth factor and its R was explored in biopsy specimens from eight patients with acute tubulointerstitial damage. In the normal human kidney, both EGF immunoreactivity and EGF mRNA were localized in tubular profiles corresponding to Henle's loop and, although to a lesser intensity, to distal convoluted tubule. EGF immunostaining was remarkable mainly at the apical surface of tubular cells. EGF-R protein expression was detected in glomerular endothelial cells, in peritubular capillaries and arteriolar walls, as well as along the thick ascending limb of Henle's lop and distal convoluted tubule, where it colocalized with Tamm-Horsfall protein. Immunohistochemical analysis of tubular profiles revealed that EGF-R was located especially along the basolateral membrane of tubular cells and within the basal part of cytoplasm. Endogenous alkaline phosphatase and CHIP28 positive tubules did not show any signal for EGF and its receptor. Kidneys with acute tubulointerstitial injury exhibited a dramatic decrease of EGF expression, whereas EGF-R showed only minor modifications. Interestingly, EGF-R was localized to both apical and antiluminal membranes of positive tubular cells. It is concluded that EGF-EGF receptor loop may be relevant in the pathogenesis of acute tubulointerstitial damage and recovery from tubular injury, while its role in the physiological renewal of the urothelium remains speculative.

We studied the expression of PDGF-a and -13 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 normalappearing kidneys, both PDGF-a and -13 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-fl 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 13 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-a receptor expression, chiefly at the interstitial level. Noteworthy, a few cases of lupus nephritis showed a moderate increase of PDGF-a receptor also at the glomerular level.These data establish PDGF-13 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-at receptor activation at the renal level remains to be elucidated. (J. Clin. Invest. 1994. 94:50-58.)

Epidermolysis bullosa (EB) consists of a group of dominant or recessive autosomal diseases characterised by skin and mucosa fragility. The lesions leave erosions and scars that, in turn, can cause stenosis of tracheal, oesophageal, and genitourinary tract mucosae. The significantly increased survival of EB patients has determined the onset of complications never observed before, including genitourinary disorders such as hydroureteronephrosis, recurrent urinary tract infections, renal amyloidosis, IgA nephropathy and post-infectious glomerulonephritis. A 6-year-old boy diagnosed with recessive dystrophic EB Hallopeau-Siemens type (RDEB-HS) was referred to our clinic because of microhaematuria that evolved into intra-infectious macrohaematuria. Renal biopsy revealed an increase in both extracellular matrix and mesangial cells, with a focal segmental glomerulosclerosis with severe chronic tubulointerstitial damage. Immunofluorescence showed IgA mesangium deposits. Five years later, he was started on haemodialysis, because of worsening renal function. This is a rare case of a child with EB who was successfully treated with haemodialysis. The pertinent literature has been reviewed.

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