Computational Prediction of Biomarkers, Pathways, and New Target Drugs in the Pathogenesis of Immune-Based Diseases Regarding Kidney Transplantation Rejection

Background

The diagnosis of graft rejection in kidney transplantation (KT) patients is made by evaluating the histological characteristics of biopsy samples. The evolution of omics sciences and bioinformatics techniques has contributed to the advancement in searching and predicting biomarkers, pathways, and new target drugs that allow a more precise and less invasive diagnosis. The aim was to search for differentially expressed genes (DEGs) in patients with/without antibody-mediated rejection (AMR) and find essential cells involved in AMR, new target drugs, protein-protein interactions (PPI), and know their functional and biological analysis.

Material and Methods

Four GEO databases of kidney biopsies of kidney transplantation with/without AMR were analyzed. The infiltrating leukocyte populations in the graft, new target drugs, protein-protein interactions (PPI), functional and biological analysis were studied by different bioinformatics tools.

Results

Our results show DEGs and the infiltrating leukocyte populations in the graft. There is an increase in the expression of genes related to different stages of the activation of the immune system, antigenic presentation such as antibody-mediated cytotoxicity, or leukocyte migration during AMR. The importance of the IRF/STAT1 pathways of response to IFN in controlling the expression of genes related to humoral rejection. The genes of this biological pathway were postulated as potential therapeutic targets and biomarkers of AMR. These biological processes correlated showed the infiltration of NK cells and monocytes towards the allograft. Besides the increase in dendritic cell maturation, it plays a central role in mediating the damage suffered by the graft during AMR. Computational approaches to the search for new therapeutic uses of approved target drugs also showed that imatinib might theoretically be helpful in KT for the prevention and/or treatment of AMR.

Conclusion

Our results suggest the importance of the IRF/STAT1 pathways in humoral kidney rejection. NK cells and monocytes in graft damage have an essential role during rejection, and imatinib improves KT outcomes. Our results will have to be validated for the potential use of overexpressed genes as rejection biomarkers that can be used as diagnostic and prognostic markers and as therapeutic targets to avoid graft rejection in patients undergoing kidney transplantation.

Local gene therapy with indoleamine 2,3-dioxygenase protects against development of transplant vasculopathy in chronic kidney transplant dysfunction

Chronic transplant dysfunction (CTD) is the primary cause of late allograft loss in kidney transplantation. Indoleamine 2,3-dioxygenase (IDO) is involved in fetomaternal tolerance and IDO gene therapy inhibits acute rejection following kidney transplantation. The aim of this study is to investigate whether gene therapy with IDO is able to attenuate CTD. Transplantation was performed in a rat Dark-Agouti to Wistar-Furth CTD model. Donor kidneys were incubated either with an adenovirus carrying IDO gene, a control adenovirus or saline. During the first 10 days recipients received low-dose cyclosporine. Body weight, blood pressure, serum creatinine and proteinuria were measured every 2 weeks. Rats were killed after 12 weeks. IDO had a striking beneficial effect on transplant vasculopathy at week 12. It also significantly improved body weight gain; it reduced blood pressure and decreased proteinuria during the follow-up. However, it did not affect the kidney function. In addition, IDO therapy significantly decreased the number of graft-infiltrating macrophages at week 12. The messenger RNA levels of forkhead box p3 and transforming grow factor-β were elevated in the IDO treated group at week 12. Here we show for first time a clear beneficial effect of local IDO gene therapy especially on transplant vasculopathy in a rat model of renal CTD.

Oral Platelet-Derived Growth Factor and Vascular Endothelial Growth Factor Inhibitor Sunitinib Prevents Chronic Allograft Injury in Experimental Kidney Transplantation Model

BACKGROUND

Expression of both platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) is increased during the development of chronic rejection which remains the major reason for late allograft loss in clinical kidney transplantation. Sunitinib is a tyrosine kinase inhibitor which inhibits both VEGF and PDGF receptors. Here we investigated its effect on the development of chronic rejection.

METHODS

Rat aortic denudation model was used to define sunitinib dose. In vitro studies were done to investigate the effect of sunitinib on smooth muscle cell proliferation and migration. Kidney transplantations were performed from dark agouti rat strain (DA) to Wistar furth rat strain rats and syngenic DA-DA grafts were used as controls. Allografts were immunosuppressed either with cyclosporine or with cyclosporine and sunitinib. Grafts were harvested at 5 and 90 days for histology and immunohistochemistry. Serum creatinine levels were measured weekly to monitor graft function.

RESULTS

Sunitinib decreased neointimal formation and smooth muscle cell proliferation and migration in a dose-dependent manner. Sunitinib was well tolerated and almost completely prevented chronic rejection changes and preserved significantly better renal graft function after transplantation. Sunitinib also inhibited chronic PDGF-A and -B and VEGF-A and -B expressions.

CONCLUSIONS

These results demonstrate that combined inhibition of PGDF and VEGF with sunitinib prevents chronic rejection changes in experimental kidney transplantation which indicates that sunitinib could be a potential intervention also in clinical kidney transplantation.

Renal effects of targeted anticancer therapies

The use of novel targeted anticancer agents has led to overall improvement in the prognosis of many patients affected by various malignancies, but has also been associated with an increased risk of poorly characterized toxic effects to different organs, including the kidneys. The high prevalence of kidney impairment in the general population complicates the issue further. Nephrologists most frequently work with patients with cancer when they are asked to investigate kidney function to assess the need for dose adjustments in anticancer therapy. A thorough knowledge of the renal safety profile of novel life-prolonging anticancer therapies, specific features of their metabolism, and pharmacokinetic and pharmacodynamic properties (under normal circumstances as well as in the setting of renal replacement therapy) is, therefore, necessary to preserve kidney function as far as possible and to ensure optimum treatment. In this Review we summarize the present knowledge of renal toxic effects from novel targeted anticancer agents and discuss whether the management of patients' treatment needs to be modified. We also advocate the development of a new onconephrology subspeciality.

Phosphodiesterase type 5 inhibition attenuates cyclosporine A induced nephrotoxicity in mice

We investigated the renal protective effects of phophodiesterase type 5 (PDE5) inhibitors in mice with cyclosporine A (CyA; a calcineurin phosphatase inhibitor) induced nephrotoxicity. Fifty male mice were divided into five groups of 10. Group 1 received no treatment, group 2 received only saline orally, group 3 received 30 mg/kg/day CyA by subcutaneous injection, group 4 received only 30 mg/kg/day vardenafil orally, and group 5 received 30 mg/kg/day CyA by subcutaneous injection and 30 mg/kg/day vardenafil orally. At 28 days, platelet-derived growth factor A (PDGF-A) and C (PDGF-C), transforming growth factor-beta 1 (TGF-β1), cyclo-oxygenase 1 and 2 (COX-1 and COX-2), and P glycoprotein (Pgp) expression levels were measured in the renal tissues. In addition, expressions of COX-1 and COX-2 genes were determined using real-time PCR. PDE5 inhibitor administration ameliorated decreased PDGF-A and C, TGF-β1, COX-1 and -2, and Pgp expression levels by modulation of cyclic guanosine monophosphate (cGMP) activity in kidneys. The relative expressions of COX-1 and COX-2 genes to GAPDH revealed that the maximum increase was obtained in the group treated with CyA and vardenafil for both COX-1 and COX-2 genes. Our study revealed that long term oral treatment with vardenafil protects kidneys from CyA induced nephrotoxicity. We showed that long term oral treatment with PDE5 prevents pathological kidney changes caused by CyA induced nephrotoxicity.

Experimental rat models of chronic allograft nephropathy: a review

Chronic allograft nephropathy (CAN) is the leading cause of late allograft loss after renal transplantation (RT), which continues to remain an unresolved problem. A rat model of CAN was first described in 1969 by White et al. Although the rat model of RT can be technically challenging, it is attractive because the pathogenesis of CAN is similar to that following human RT and the pathological features of CAN develop within months as compared with years in human RT. The rat model of RT is considered as a useful investigational tool in the field of experimental transplantation research. We have reviewed the literature on studies of rat RT reporting the donor and recipient strain combinations that have investigated resultant survival and histological outcomes. Several different combinations of inbred and outbred rat combinations have been reported to investigate the multiple aspects of transplantation, including acute rejection, cellular and humoral rejection mechanisms and their treatments, CAN, and potential targets for its prevention.

Dasatinib-induced nephrotic-range proteinuria

Since the introduction of imatinib, tyrosine kinase inhibition has been a mainstay in the treatment of many malignancies. The number of these medications is growing, as are the number of targeted tyrosine kinases. Off-target effects of these medications can have beneficial or adverse effects on the kidney. The onus of knowing the implications of these medications on kidney function, and appropriate treatment when such adverse effects occur, is on the nephrologist. We present a patient with chronic myelogenous leukemia who developed nephrotic-range proteinuria after initiation on dasatinib therapy that resolved after changing therapy to imatinib. The mechanism of kidney injury caused by dasatinib has not been described previously in the literature. We provide a review of vascular endothelial growth factor and its pharmacologic inhibition as it pertains to kidney pathology and propose possible mechanisms by which dasatinib induces kidney injury.

Long- and short-term treatment with imatinib attenuates the development of chronic kidney disease in experimental anti-glomerular basement membrane nephritis

BACKGROUND

Imatinib is a selective tyrosine kinase inhibitor that can block platelet-derived growth factor (PDGF) receptor activity. Imatinib is also known as an anti-inflammatory agent. We examined the therapeutic effects of long- or short-term imatinib treatment in Wistar-Kyoto (WKY) rats with established anti-glomerular basement membrane (GBM) nephritis.

METHODS

Nephrotoxic serum (NTS) nephritis was induced in WKY rats on day 0. Groups of animals were given either imatinib or vehicle daily by intraperitoneal injection, from day 7 to day 49 in the long-term treatment study, and from day 7 to 13 in the short-term treatment study; all rats were sacrificed at day 50.

RESULTS

In long-term treatment, imatinib showed marked renoprotective effects; imatinib suppressed proteinuria, improved renal function, attenuated the development of glomerulosclerosis and tubulointerstitial injury and reduced the expression levels of collagen type I and transforming growth factor-beta (TGF-β) in renal cortex. The key finding of the present study was that short-term treatment with imatinib also significantly attenuated the development of renal injury until day 50, although the degree of renoprotection was slightly inferior to that of long-term treatment.

CONCLUSIONS

These results suggest that administration of imatinib is a promising strategy for limiting the progression of glomerulonephritis (GN) to end-stage renal failure. In particular, a short period of treatment at an early stage of GN is more beneficial in terms of cost-effectiveness and reduction of adverse effects in comparison to a continuous and long period of treatment.