Experimental ablation nephropathy. Fine structure, morphometry, cell membrane epitopes, glomerular polyanion and effect of subsequent transplantation

Bisphenol A Modulates Autophagy and Exacerbates Chronic Kidney Damage in Mice

BACKGROUND

Bisphenol A (BPA) is a ubiquitous environmental toxin that accumulates in chronic kidney disease (CKD). Our aim was to explore the effect of chronic exposition of BPA in healthy and injured kidney investigating potential mechanisms involved.

METHODS

In C57Bl/6 mice, administration of BPA (120 mg/kg/day, i.p for 5 days/week) was done for 2 and 5 weeks. To study BPA effect on CKD, a model of subtotal nephrectomy (SNX) combined with BPA administration for 5 weeks was employed. In vitro studies were done in human proximal tubular epithelial cells (HK-2 line).

RESULTS

Chronic BPA administration to healthy mice induces inflammatory infiltration in the kidney, tubular injury and renal fibrosis (assessed by increased collagen deposition). Moreover, in SNX mice BPA exposure exacerbates renal lesions, including overexpression of the tubular damage biomarker Hepatitis A virus cellular receptor 1 (Havcr-1/KIM-1). BPA upregulated several proinflammatory genes and increased the antioxidant response [Nuclear factor erythroid 2-related factor 2 (Nrf2), Heme Oxygenase-1 (Ho-1) and NAD(P)H dehydrogenase quinone 1 (Nqo-1)] both in healthy and SNX mice. The autophagy process was modulated by BPA, through elevated autophagy-related gene 5 (Atg5), autophagy-related gene 7 (Atg7), Microtubule-associated proteins 1A/1B light chain 3B (Map1lc3b/Lc3b) and Beclin-1 gene levels and blockaded the autophagosome maturation and flux (p62 levels). This autophagy deregulation was confirmed in vitro.

CONCLUSIONS

BPA deregulates autophagy flux and redox protective mechanisms, suggesting a potential mechanism of BPA deleterious effects in the kidney.

Suitability of 5/6 nephrectomy (5/6NX) for the induction of interstitial renal fibrosis in rats--influence of sex, strain, and surgical procedure

Chronic renal failure (CRF) is a serious clinical problem and currently there are no adequate therapeutic strategies for treatment. Many possible treatment strategies have been tested in rats with CRF induced by subtotal nephrectomy. However, reports in the literature concerning the consequences of this procedure on rat kidney function are contradictory. For instance, such an intervention in male Sprague-Dawley rats apparently initiates the development of interstitial renal fibrosis, while in our similar studies on female Wistar rats (HW) there was minimal renal fibrosis. Therefore, we carried out experiments in adult rats to investigate the long-term consequences of 5/6 nephrectomy (5/6NX) in relation to (1) sex, (2) strain, and (3) two methods of surgical ablation. Ten weeks after 5/6NX, body weight gain, systolic blood pressure, creatinine clearance, and urinary protein were measured, along with renal hydroxyproline concentration determinations to assess the deposition of extracellular matrix. Also, light microscopic investigations were done to characterize renal damage. The functional parameters clearly indicated the development of CRF, while morphologic investigations showed only moderate fibrotic areas containing atrophic tubules and lymphocytic infiltrates. However, 45-60% of glomeruli were sclerotic. In summary, 5/6NX, using either method of partial nephrectomy, induces signs of moderate glomerulonephritis preferentially in female HW rats. Thus 5/6NX in female HW rats can be recommended as a suitable model in the induction of renal fibrosis.

Abnormal differentiation of thymocytes induced by free cyclosporine is avoided when cyclosporine bound to N-(2-hydroxypropyl)methacrylamide copolymer carrier is used

BACKGROUND

The side effects of cyclosporine (CsA)-including nephrotoxicity and abnormal differentiation of thymocytes developing in the thymus-can be decreased or even avoided using targeted conjugates of CsA, where both targeting moiety and drug are bound to water-soluble polymeric carrier based on N-(2-hydroxypropyl) methacrylamide (HPMA).

METHODS

Irradiated, syngeneic bone marrow transplanted-mice (BALB/c and A/Ph) were treated intraperitoneally for 4 weeks with 20 mg/kg of free CsA, HPMA-conjugated CsA, or antibody-targeted HPMA-bound CsA. Immunohistology of the thymus was performed together with two-color flow cytometry to detect the effect of different forms of CsA on individual thymocyte subpopulations.

RESULTS

. We have shown that free CsA strongly abrogated T-cell development. The appearance of mature thymocytes expressing CD3(high) is almost completely inhibited (1.8%) after free CsA treatment, whereas these cells are well detectable in controls (22%) and HPMA polymer-bound CsA-treated animals (19%). Immunohistological studies have shown acellular rests of the medulla after free CsA treatment, whereas well-stained medullary thymocytes were detected in controls and after exposure to antibody-targeted HPMA. conjugated CsA.

CONCLUSIONS

HPMA-conjugates of CsA are generally more specific in their targeting to T lymphocytes. It was found that nonspecific binding of CsA to erythrocytes and plasma lipoproteins is significantly reduced using anti-CD3 targeted, HPMA polymer-bound CsA In addition, the entry of these macromolecules into the thymus is limited-probably due to the blood-thymus barrier-and HPMA conjugates of CsA, unlike free drug, do not abrogate T-cell development in bone marrow transplanted mice.

Morphology of rat kidney and thymus after native and antibody-coupled cyclosporin A application (reduced toxicity of targeted drug)

This study compares the toxic effects of native cyclosporia A (CyA) with those of targeted CyA that is conjugated with the anti-rat-thymocyte antibody of rabbit origin via the N-(2-hydroxypropyl)methacrylamide (HPMA) carrier bearing digestible, reactive oligopeptide side chains. Ten toxic doses of native CyA (50 mg/kg i.p.) given to young adult rats in the course of 14 d produced a severe renal lesion-diffuse microvacuolization of the proximal tubules in the deep cortex, and hypergranulation of juxtaglomerular regions. Severe atrophy of the thymic medulla was documented by morphometry. In the cortex the epithelial reticular (but not deep interdigitating) cells showed ultrastructural signs of severe degeneration and lysis. The immature CD4+8+ double-positive cortical lymphocytes were preserved whereas the single-positive medullary thymocytes were greatly depleted; there was also a restriction of MHC class II antigen expression in the medulla. The number of medullary B cells was increased. The cytokeratin net was focally shrunken in the cortex and almost negative in the medulla, with loss of Hassall's corpuscles. After ten corresponding doses of antibody-targeted conjugated CyA no damage to the renal tubules and arterioles appeared and the antiGBM or immune-complex deposition was absent. The thymus had a normal medulla with numerous mature thymocytes and the cortical epithelial reticulum remained well preserved. Thus, the main toxic effects of CyA could be eliminated by targeting. The T-cell-targeted drug was tested for preserved immunosuppressive properties and non-toxic character of HPMA copolymer carrier.

Experimental adriamycin nephropathy. Fine structure, morphometry, glomerular polyanion, and cell membrane antigens

Two doses of adriamycin (2 mg/kg i.v.) were administered to young adult rats with a 22-day interval and the kidneys were examined 51, 79, and 107 days after the first injection. Light microscopy showed early prominent intraglomerular microcystic spaces and progressive, though not severe, segmental glomerulosclerosis with focal interstitial scarring and round-cell infiltration. The main features of the ultrastructure were widespread fusion of foot processes, focal cytoplasmic rarefaction of podocytes, and non-specific sclerosis of the mesangium without signs of severe degenerative changes or mesangiolysis. The segmental microcystic structures corresponded to agglomerated intrapodocytic vacuoles. The scatter of glomerular polyanion sites visualized by polyethylenimine-phosphotungstic acid resembled that of control animals but the quantitative assessment revealed a significant reduction. CD4-positive cells were the predominant element of the interstitial infiltrates. Most of the infiltrating cells expressed Ia antigens, whereas Ia-positive intraglomerular resident mononuclear cells were depleted. The adriamycin lesion resembles the post-five-sixths nephrectomy ablation nephropathy in the subpopulations of the interstitial infiltrate but differs from it in the reduction of intraglomerular resident macrophages, the absence of destructive mesangial damage, and reduced segmental glomerulosclerosis. The main feature is the prolonged damage of podocytes, especially of their cytoskeletal system.