Effect Of Bufalin Against Proteinuria Of Adriamycin-induced Nephritic Rats And Its Underlying Mechanisms

BackgroundProteinuria is an important risk factor for the progression and prognosis ofchronic kidney disease. Proteinuric diseases are still formidable challenges innephrology. Although glucocorticoids remain the mainstay of treatment forproteinuric diseases, many patients have to give it up because of serious side effectsascribed long-term use of Glucocorticoids, drug resistance and recurrence frequently,and then try to accecpt sequential treatment of Immunosuppressants. Many patientsare still difficult to have satisfactory treatment protocols because of more toxicityand resistance of Immunosuppressants. Therefore, the development of new drugswhich are effective for proteinuric diseases but have little side effects will become aresearch hotspot.Bufalin (C24H3404) is a major active component of Chinese medicine Chan Su,which has a variety of biological activities, including cardiotonic, antineoplasticactivities, anti-inflammatory, and regulates the immune responses. A previous studyin China found that Chan Su could protect the renal function in chronic renal failureand reduce urinary protein excretion in the ADR-induced nephritic rats. Becausebufalin is a major component of Chan Su, we are interested in the role of bufalin inreducing proteinuria. We had no found results in previous literatures. Our study is toreveal that bufalin affects proteinuria with comparable therapeutic efficacy toprednisone and tries to illustrate its underlying mechanisms in an ADR-inducedMCNS rat model. Methods1. The24-h urine protein excretion in all rats was determined using acolorimetric assay and the biochemical indices in blood serum weremeasured with a completely automatic biochemical analyser.2. The basic tissue structure of kidney, heart and liver was observed under alight microscopy.3. The ultrastructural changes of podocyte were examined in a transmissionelectron microscope.4. The distribution of the podocyte-associated molecules was comparedutilising immunohistochemical staining.5. Effect of bufalin on mRNA expression of podocyte-associated moleculeswas detemined by RT-PCR.6. Effect of bufalin on protein expression of podocyte-associated moleculeswas detemined by western blotting.Results1. Bufalin or prednisone could reduce the urinary protein excretion andoptimise the lipidaemia and the serum albumin of the ADR rats, but did notaffect the function of kidney, heart and liver.2. We had no found notably pathological changes in kidney, heart and livertissues in ADR rats with bufalin or prednisone treament.3. We noticed a somatic swelling of the podocytes, the increasing podocytefoot process effacement and the thickening of the GBM in ADR rats overtime, but these were markedly improved with bufalin or prednisonetreatments at the same time.4. The distribution of podocyte-associated molecules such as nephrin,podocin and ILK was changed to abnormal in a varying degree in ADR rats.Treatment with bufalin or prednisone alleviated the changes of the distribution of three molecules.5. Bufalin inhibited the up-regulation of podocin and ILK in mRNA levelsbut did not affect nephrin mRNA levels on the renal cortex of the ADR rats.6. Bufalin notably decreased the expression of nephrin and ILK butinhibited the down-regulation of podocin in protein levels on the renalcortex of the ADR rats.ConclusionBufalin could reduce proteinuria by attenuation of glomerular filtration barrierdamage in adriamycin-induced nephropathic rats.The underlying mechanism mightbe associated with the restoration of the transcription, expression and distribution ofpodocyte-associated proteins.