Szabolcs Gomba

Tissue transglutaminase (TG2) acting as G protein protects hepatocytes against Fas‐mediated cell death in mice

Tissue transglutaminase (TG2) is a protein cross‐linking enzyme known to be expressed by hepatocytes and to be induced during the in vivo hepatic apoptosis program. TG2 is also a G protein that mediates intracellular signaling by the alpha‐1b‐adrenergic receptor (AR) in liver cells. Fas/Fas ligand interaction plays a crucial role in various liver diseases, and administration of agonistic anti‐Fas antibodies to mice causes both disseminated endothelial cell apoptosis and fulminant hepatic failure. Here we report that an intraperitoneal dose of anti‐Fas antibodies, which is sublethal for wild‐type mice, kills all the TG2 knock‐out mice within 20 hours. Although TG2−/− thymocytes exposed to anti‐Fas antibodies die at the same rate as wild‐type mice, TG2−/− hepatocytes show increased sensitivity toward anti‐Fas treatment both in vivo and in vitro, with no change in their cell surface expression of Fas, levels of FLIPL (FLICE‐inhibitory protein), or the rate of I‐κBα degradation, but a decrease in the Bcl‐xL expression. We provide evidence that this is the consequence of the impaired AR signaling that normally regulates the levels of Bcl‐xL in the liver. In conclusion, our data suggest the involvement of adrenergic signaling pathways in the hepatic regeneration program, in which Fas ligand‐induced hepatocyte proliferation with a simultaneous inhibition of the Fas‐death pathway plays a determinant role. (HEPATOLOGY 2005.)

Renal cell cancer associated with sarcoid-like reaction

An unusual granulomatous reaction within a conventional clear cell renal cancer in a 62 year-old woman is reported. Using immunohistochemical evaluation, cells of the granuloma were CD68 (Kp1), carboxypeptidase M and CD3 positive. No signs of sarcoidosis were found in other organs. According to the few publications that mention cancer associated sarcoid-like reaction, such lesions do not influence the prognosis. Our patient is still well for a 15 months follow-up.

Analysis of the Role of Apoptosis and Cell Proliferation in Renal Cystic Disorders

Cell proliferation and apoptosis were studied in 8 patients with inherited polycystic kidney disease and in 34 patients with acquired cystic kidney conditions including solitary and multilocular cysts and segmental tubular dilation. Intact renal tissue of 20 surgically removed tumorous kidneys served as control. Cell proliferation and apoptosis were demonstrated by immunohistochemical and in situ end–labeling methods. The percentage of positively stained nuclei was calculated and statistically analyzed. Both apoptosis and cell proliferation were significantly higher (p<0.001) in polycystic kidney disease. The percentage of positively stained nuclei in the whole kidney tissue with acquired cysts did not differ from controls although cell proliferation was significantly higher (p<0.001) in cells lining the cysts. Apoptotic cells were rarely found in the cystic epithelium or were even absent in these cases. Our data indicate that while polycystic kindneys seem to be characterized by abnormal cell survival, acquired renal cysts have different behavior in which so far unknown intracellular changes are more likely to cause tubular distension probably through induced cell proliferation.

A novel method of macropathologic and arteriographic examination of carotid specimens obtained from autopsy

Twenty carotid bifurcations were examined. During autopsy, carotid bifurcations were removed in toto. Unfixed carotids were ligated and cannulated for injection of an angiographic contrast medium followed by injection of a tissue-embedding medium at physiologic pressure and temperature. The carotid bifurcation was frozen and cut manually in 3-mm cross-sections. Photographs were then taken of every slice. Angiography, filling with tissue-embedding material, and sectioning were successful in all cases. In the macropathologic sections, the extent, configuration and location of atherosclerotic lesions could be identified.

Evaluation of apoptosis and cell proliferation in experimentally induced renal cysts

Abstract Cell proliferation and apoptosis in renal cysts induced by streptozotocin, alloxan and ferric-nitrilotriacetate were investigated in rats. In the kidneys of all treated animals dilated tubules at the cortico-medullary region, large cysts, glomerular cysts and tubular dilation in the medullary area were found. Both cell proliferation and apoptosis were increased in the epithelium of the non-dilated tubules, in the mesangial and interstitial cells. Cells lining the dilated tubules or cysts demonstrated apoptosis but their proliferating activity was low. By calculating the proliferation–apoptosis ratio we found that alloxan did not change the balance between the two mechanisms. Meanwhile streptozotocin resulted in an increased apoptosis and ferric-nitrilotriacetate in an increased cell proliferation. p53 expression might be responsible for the uncontrolled proliferation in rats treated with ferric-nitrilotriacetate as this oncoprotein was diffusely present in tubular cell nuclei. The observed apoptosis seemed to be independent of bcl-2 oncoprotein expression. We assume that the initial factor in such cystogenesis should be a cellular injury due to direct toxic or to the diabetogenic effect of the drugs. The latter is more likely as all the animals were hyperglycemic and insulin treatment following administration of streptozotocin prevented the morphologic changes.

Severe burn injury induces a characteristic activation of extracellular signal-regulated kinase 1/2 in spinal dorsal horn neurons

We have studied scalding-type burn injury-induced activation of extracellular signal-regulated kinase 1/2 (ERK1/2) in the spinal dorsal horn, which is a recognised marker for spinal nociceptive processing. At 5min after severe scalding injury to mouse hind-paw, a substantial number of phosphorylated ERK1/2 (pERK1/2) immunopositive neurons were found in the ipsilateral dorsal horn. At 1h post-injury, the number of pERK1/2-labelled neurons remained substantially the same. However, at 3h post-injury, a further increase in the number of labelled neurons was found on the ipsilateral side, while a remarkable increase in the number of labelled neurons on the contralateral side resulted in there being no significant difference between the extent of the labelling on both sides. By 6h post-injury, the number of labelled neurons was reduced on both sides without there being significant difference between the two sides. A similar pattern of severe scalding injury-induced activation of ERK1/2 in spinal dorsal horn neurons over the same time-course was found in mice which lacked the transient receptor potential type 1 receptor (TRPV1) except that the extent to which ERK1/2 was activated in the ipsilateral dorsal horn at 5 min post-injury was significantly greater in wild-type animals when compared to TRPV1 null animals. This difference in activation of ERK1/2 in spinal dorsal horn neurons was abolished within 1h after injury, demonstrating that TRPV1 is not essential for the maintenance of ongoing spinal nociceptive processing in inflammatory pain conditions in mouse resulting from at least certain types of severe burn injury.

Evidence for lysosomal matrix in the juxtaglomerular cell granules

A systematic histochemical analysis of the matrix composition of juxtaglomerular cell granules was carried out. The behaviour of kidney lysosomes under similar conditions has been examined in parallel. The tubular protein droplets produced by the i.p. administration of egg albumen were chosen as lysosome-model. Identical pattern of histochemical reactions has been demonstrated both in kidney lysosomes and juxtaglomerular granules indicating the presence of separate lipoprotein and glycoprotein components. The ammoniated silver carbonate method for lysosomes was also positive in juxtaglomerular cell granules. These results support on a non-enzymatic basis the concept that secretory granules and lysosomes are evolutionary homologues.

Accumulation of Hg(II) Ions in Mouse Adrenal Gland.

Female BALBc mice were administered HgCl2 at a single dose of 4 mg/kg i.p. The acute intoxication with Hg(II) salts (2 hr) caused accumulation of Hg(II) ions in the adrenal gland in general, and in the medulla, in particular. Based on data obtained with atomic absorption spectroscopy and quantitative cytochemistry, we determined the amount of mercury (II) in the adrenal glands and found it to be 14.2 ng Hg(II) (3.5 mg/kg wet weight of the adrenals). An uneven distribution of Hg(II) was found within the adrenal gland, not only between the medulla and cortex, but also within the cortex. The applied autometallographic method revealed that the cortex was negative except the zona glomerulosa, whereas the medulla showed a strong reaction localised to the chromaffin granules of the secretory cells. Both adrenaline and noradrenaline producing cells reacted. The comparison of the density of silver grains by scanning densitometry in the medulla and cortex revealed a significantly higher Hg(II) concentration in the medulla compared to the cortex (10 mg/kg vs 2 mg/kg, respectively). The results presented here suggest that there may be a connection between the symptoms of acute Hg(II) intoxication and its adrenal accumulation.

Comparison of the morphology of renal cysts and cystic renal tumors

Renal tumors appear uncommonly with cystic changes. They may develop due to necrosis though well-formed real cysts are also known. Such lesions may present problems in distinguishing them from benign renal cysts. Conditions leading to cyst formation are not known, however cell proliferation, altered extracellular matrix production and oncoprotein expression have been reported in cystic renal disorders. In the present study, we analysed the morphological features of 23 cystic renal tumors in comparison with 16 benign cysts using immunohistochemical and lectin binding methods. By our knowledge there has not been any publication on such studies. The cystic renal tumors were represented predominantly in males and the size of the cysts was slightly larger than that of benign cysts. Tumorous cysts shared similar morphological appearance to solitary and multilocular cysts. They all showed strong epithelial membrane antigen reactivity on the luminal surface of the cells indicating distal tubular origin. Cell proliferation and p53 expression proved to be low excluding their role in the formation of the cysts. The amount of extracellular matrix and basement membrane was increased with an elevated type IV collagen and reduced fibronectin content. Polycystic kidney disease is different from tumorous cysts as cell proliferation, p53 oncoprotein expression and the composition of extracellular matrix proved to be the opposite. As renal cell tumors arise from proximal tubules, neoplastic or metaplastic differentiation toward distal tubular direction seems to be the key event in cyst formation. Altered cell-matrix or cellcell contact can modulate this transformation providing a basis for further results.