Leonid Kachko

Reduction of cPLA2alpha overexpression: an efficient anti-inflammatory therapy for collagen-induced arthritis.

Cytosolic phospholipase A2α (cPLA2) plays an important role in the development of several inflammatory diseases. The aim of the present study is to determine whether inhibition of cPLA2 expression, using specific antisense oligonucleotides against cPLA2 (antisense), is efficient in reducing inflammation after its development. Two mouse models of inflammation were included in the study: thioglicolate peritonitis and collagen‐induced arthritis (CIA). The antisense was found to be specific and efficient in inhibiting cPLA2 expression and NADPH oxidase activity ex vivo in peritoneal phagocytes. Immunoblotting and immunohistochemistry analysis showed a significant elevation in cPLA2 expression in the inflamed joints of collagen‐induced arthritis mice localized in cell infiltrate, chondrocytes and the surrounding skin and skeletal muscle. Similarly, the cPLA2 metabolite, leukotriene B4, accumulated in the peritoneal cavity of mice with peritonitis. Inhibition of elevated cPLA2 expression after development of inflammation by intravenous administration of antisense resulted in a dramatic reduction in inflammation and a significant reduction in neutrophils recruitment to the site of inflammation in both mouse models of inflammation. Our results demonstrate the critical role of cPLA2 for the duration of inflammation and suggest that inhibition of cPLA2 expression by antisense oligonucleotides may serve as an efficient treatment of inflammatory diseases.

Epidermolysis bullosa, pyloric atresia, aplasia cutis congenita : Histopathological delineation of an autosomal recessive disease

The simultaneous appearance of epidermolysis bullosa and pyloric atresia (EB-PA) is recognized as an autosomal recessive disease; however, the coappearance of EB-PA and aplasia cutis congenita (ACC) has not been delineated as a defined entity. The aim of this study was to analyze clinically and histopathologically eight cases with EB-PA-ACC belonging to an extended Bedouin family to gain insight into the cause and pathophysiology of the disease. All affected infants were found to have mixed skin lesions, including blisters and patchy lack of skin. Almost all of them (seven of eight) also had intestinal obstructions, especially pyloric atresia or stenosis. Skin lesions involved all skin layers with marked dystrophic changes. The intestinal obstruction was the result of overproliferation of connective tissue. In view of the clinical and histopathological findings, it is postulated that the condition is caused by an autosomal recessive gene affecting the integrity of the basement membrane and hemidesmosomes and the control of the normal process of fibrosis occurring during the course of wound healing. The sequence of events is initiated by the separation of the epidermis or the intestinal mucosal layer. Then, inflammatory reaction takes place and proceeds with massive fibrosis penetrating the deep layers and causing damage of skin and obstruction of the intestinal lumen. In view of the recent findings regarding the molecular basis of EB-PA, the described phenotype may result from a mutation in one of the integrin genes.

Epiphyseal growth plate growth hormone receptor signaling is decreased in chronic kidney disease–related growth retardation

Linear growth retardation in children with chronic kidney disease (CKD) has been ascribed to insensitivity to growth hormone. This resistance state has been attributed to impaired growth hormone signaling through the JAK2/STAT5 pathway in liver and skeletal muscle leading to reduced insulin-like growth factor-I (IGF-I). Here we determine whether systemic and growth plate alterations in growth hormone signaling contribute to CKD-induced linear growth retardation using partially nephrectomized and pair-fed control 20-day-old rats. Serum growth hormone did not change in rats with CKD, yet serum IGF-I levels were decreased and growth retarded. The tibial growth plate hypertrophic zone was wider and vascularization at the primary ossification center was reduced in CKD. This was associated with a decrease in growth plate vascular endothelial growth factor (VEGF) mRNA and immunostainable VEGF and IGF-I levels. Growth plate growth hormone receptor and STAT5 protein levels were unchanged, while JAK2 was reduced. Despite comparable growth hormone and growth hormone receptor levels in CKD and control rats, relative STAT5 phosphorylation was significantly depressed in CKD. Of note, the mRNA of SOCS2, an inhibitor of growth hormone signaling, was increased. Thus, linear growth impairment in CKD can in part be explained by impaired long bone growth plate growth hormone receptor signaling through the JAK2/STAT5 pathway, an abnormality that may be caused by an increase in SOCS2 expression.

Blocking adenosine A2A receptor reduces peritoneal fibrosis in two independent experimental models

BACKGROUND Long-term peritoneal dialysis (PD) is associated with peritoneal fibrosis and loss of function. It has been shown that activation of the adenosine A(2A) receptor (A(2A)R) promotes tissue repair, wound healing and extracellular matrix (ECM) production. We have previously shown that adenosine is a potent regulator of inflammation in the peritoneum. In the current study, we explored the role of adenosine and the A(2A)R in two experimental models. METHODS Collagen deposition was evaluated in primary peritoneal fibroblasts following treatment with an A(2A)R agonist and antagonist. In addition, peritoneal fibrosis was induced by i.p. injection of either chlorhexidine gluconate for 2 weeks or 4.25% glucose peritoneal dialysis fluid (PDF) for 1 month. The development of fibrosis was compared between wild-type (WT) and WT mice treated with caffeine (an A(2A)R antagonist) in drinking water or between (A(2A)R(+/+)) mice and A(2A)R-deficient mice (A(2A)R(-/-)). RESULTS Adenosine or the A(2A)R agonist CGS21680 stimulated collagen production by peritoneal fibroblasts in vitro and A(2A)R antagonists (ZM241385 and caffeine) blocked this effect. Consistent with these results, caffeine-treated WT or A(2A)R(-/-) mice had reduced submesothelial thickness, collagen deposition and mRNA levels of fibroblast-specific protein (FSP-1) and connective tissue growth factor (CTGF). In addition, treatment with caffeine in vitro and in vivo diminished A(2A)R and A(2B)R mRNA levels induced by CG or PDF while it upregulated A(1)R levels. CONCLUSION Our data suggest that adenosine through its A(2A)R promotes peritoneal fibrosis and therefore should be considered as a target for pharmacological intervention.

Toxic effects of subconjunctival 5-fluorouracil and mitomycin C on ciliary body of rats.

Purpose: The effects of subconjunctival injection of mitomycin C and different concentrations of 5-fluorouracil on the epithelium of the ciliary body of twenty Sprague Dawley SD rats was studied.Methods: Twenty rats were divided into four treatment groups.The first three groups received 0.2 ml of 5, 10, and 30 mg of 5-fluorouracil subconjunctivally respectively, and the fourth group 0.2 ml of 0.4 mg/ml mitomycin C subconjunctivally. The right eye received 0.2 ml of the antimetabolite,while the left eye was injected with 0.2 ml of saline subconjunctivally, as a control.The eyes were examined histologically, in a masked fashion, by light and bytransmission electron microscopy. In each treatment group, two eyes were examined after one week, and three eyes were examined one month after the subconjunctival injection. Results: Electron microscopy revealed toxic effects in the epitheliumof the ciliary body of all treatment groups. The 5-fluorouracil group revealed focal mitochondrial edema, enlargement of intercellular spaces, and dilatation of intracellular spaces. The mitomycin C group showed pyknotic nuclei,enlargement of intercellular spaces, and irregular flattened epithelial cells. Theseverity of changes correlated with concentration and length of exposure. No pathology was found by light microscopy in all groups.Conclusions: This study demonstrates that subconjunctival antimetabolites mitomycin C and 5-fluorouracil can penetrate the sclera and exert toxiceffects on the epithelium of the ciliary body, even in low doses. These changeswere only apparent by electron microscopy and were still present one month after theinjection. These findings may contribute to the theory that the application ofantimetabolites during or after surgery has a direct effect on the epithelium of the ciliary body, besides its known effect on the conjunctiva. Further studies are needed to evaluate its effect on intraocular pressure.

Diffuse lentiginosis in a patient with Werner's syndrome—a possible association with incomplete leopard syndrome

A classical case of Werners syndrome is described. In addition to the numerous skin changes that are typically associated with Werners syndrome, our patients also displayed diffuse lentiginosis, and several of the clinical features of leopard syndrome. Histopathological and ultrastructural findings from a hyperpigmented maculae displayed the typical features of a simple lentigo. A striking feature was the presence of melanosomes in Langerhans cells as has been reported in the leopard syndrome. A possible generalized mesodermal defect has been suggested in Werners syndrome, while the basic defect in the leopard syndrome is thought to be of neuroectodermal origin with pleiotropic changes in the organs derived from the mesoderm. Our patient, with incomplete leopard syndrome and typical Werners syndrome, may be an example of an association of genetic defects affecting both tissues of neuroectodermal and mesodermal origin.

Keratosis Lichenoides Chronica : A Variant of Lichen Planus

In order to establish a possible relationship between keratosis lichenoides chronica (KLC) and lichen planus (LP), we performed a comparative study which included routine histologic examination, electron microscopy, and direct immunohistochemical studies from one case of KLC and several patients with LP. Our findings demonstrate that KLC and LP share many similarities; their differences are mostly quantitative. In KLC, the findings are more prominent; we therefore conclude that KLC is at one end of the spectrum of LP.

Induction of conduction block by Campylobacter jejuni lipopolysaccharides and focal neural insult

A systemic exposure to gram negative LPS have caused transient conduction abnormalities in a certain strain of rats probably associated with the action of cytokines secreted by macrophages. Our previous studies demonstrated that anti-GM1 antibodies induced in rats by the cross-reactive Cj-LPS, caused no conduction abnormalities. We designed the present study to evaluate the effect of systemic exposure to Cj-LPS on nerve conduction after a focal minor neural trauma. Female Lewis rats were sensitized against KLH by repetitive subcutaneous injections. After 28 days rats were intraneurally injected with saline in the right sciatic nerve and concomitantly with intraperitoneal Cj-LPS. Sciatic nerve conduction studies were performed on days 0, 1, 2, 3, and 7 after injections. Nerve conduction blocks developed in all the rats (n=10) which received an intraneural injection of saline concomitantly with the systemic Cj-LPS exposure, before titers of anti-ganglioside antibodies were detected. We conclude that humoral factors (possibly cytokines), other than antibodies are secreted by lymphocytes and macrophages stimulated by gram negative LPS, and cause functional conduction abnormalities when the blood-nerve barrier is disrupted.

Impaired renal growth hormone JAK/STAT5 signaling in chronic kidney disease

BACKGROUND Treatment with recombinant human growth hormone (GH) is the standard therapy for short stature in children with chronic kidney disease (CKD). However, concerns have been raised on the potential renal fibrogenic effects of GH. There is no information regarding the renal GH receptor (GHR)-JAK-STAT signaling pathway in CKD. METHODS Subtotal nephrectomized (CKD) and pair-fed sham-operated control (C) juvenile rats were treated with subcutaneous GH or saline for 2 weeks. A single intravenous GH bolus or vehicle was provided prior to euthanasia. RESULTS Reduced body weight in CKD was improved with GH therapy. The remnant kidney showed glomerular hypertrophy and early interstitial fibrosis without inflammatory infiltration. Treatment of CKD rats with GH did not worsen renal function or fibrosis. Kidney GHR mRNA and protein levels were reduced and basal phosphorylation of JAK2 and STAT5 was significantly impaired. However, intravenous GH administration prior to sacrifice normalized STAT5 phosphorylation. Basal renal IL6 mRNA and phosphorylation of its downstream signaling molecule STAT3 were increased as was the product of its action, the suppressor of cytokine signaling 3 (SOCS3) mRNA. CONCLUSIONS Despite known unaltered circulating GH levels, remnant kidneys of uremic growth retarded juvenile rats show impaired basal signaling along the GH-activated JAK2/STAT5 signaling pathway. This may well be a consequence of the reduced GHR level and the inhibitory effect of the increase in IL-6-mediated SOCS3 expression. This renal GH insensitivity, if present in humans, may protect against the potential adverse renal effects of GH administration in CKD patients.

Ovarian signet-ring stromal tumor: a potential diagnostic pitfall.

Signet-ring stromal tumor is a rare ovarian neoplasm with only 10 reported cases in the literature. We report an unusual case of ovarian signet-ring stromal tumor in a 69-year-old woman who presented with right adnexal mass and underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy. The diagnosis was based on histological, histochemical, immunohistochemical, and electron microscopy characteristics. The main significance is to differentiate this benign tumor from the highly malignant Krukenberg tumor, and this differential diagnosis is discussed.