Glomerular targeting of acidic fibroblast growth factor-1 in renal transplanted rats

A new, accurate predictive model for incident hypertension

OBJECTIVE

Data mining represents an alternative approach to identify new predictors of multifactorial diseases. This work aimed at building an accurate predictive model for incident hypertension using data mining procedures.

METHODS

The primary study population consisted of 1605 normotensive individuals aged 20-79 years with 5-year follow-up from the population-based study, that is the Study of Health in Pomerania (SHIP). The initial set was randomly split into a training and a testing set. We used a probabilistic graphical model applying a Bayesian network to create a predictive model for incident hypertension and compared the predictive performance with the established Framingham risk score for hypertension. Finally, the model was validated in 2887 participants from INTER99, a Danish community-based intervention study.

RESULTS

In the training set of SHIP data, the Bayesian network used a small subset of relevant baseline features including age, mean arterial pressure, rs16998073, serum glucose and urinary albumin concentrations. Furthermore, we detected relevant interactions between age and serum glucose as well as between rs16998073 and urinary albumin concentrations [area under the receiver operating characteristic (AUC 0.76)]. The model was confirmed in the SHIP validation set (AUC 0.78) and externally replicated in INTER99 (AUC 0.77). Compared to the established Framingham risk score for hypertension, the predictive performance of the new model was similar in the SHIP validation set and moderately better in INTER99.

CONCLUSION

Data mining procedures identified a predictive model for incident hypertension, which included innovative and easy-to-measure variables. The findings promise great applicability in screening settings and clinical practice.

Adeno-associated viral vector-mediated interleukin-10 prolongs allograft survival in a rat kidney transplantation model

Interleukin-10 (IL-10) is a pleiotropic cytokine that plays a pivotal role in the regulation of immune responses. Hence, we evaluated the effects of a recombinant adeno-associated viral vector 1 (rAAV1) encoding rat IL-10 (rAAV1-IL-10) in a rat model of kidney allograft rejection. Dark Agouti rat kidneys were transplanted into Wistar-Furth (WF) rats 8 weeks following a single intramuscular administration of either rAAV1-IL-10 or rAAV1-green fluorescence protein (GFP). Isografts (WF-WF) served as an additional experimental control. Both allograft and isograft recipients received daily cyclosporine (10 mg/kg) for 14 days after transplantation. Serum IL-10 levels increased at 8, 12 and 16 weeks following vector administration in rAAV1-IL-10-treated animals, but not in rAAV1-GFP and isograft groups. rAAV1-IL-10 treatment resulted in lower BUN and creatinine levels (p<0.001), as well as increased allograft survival rates from 22% to 90%. Allograft histological abnormalities were significantly attenuated in the rAAV1-IL-10-treated rats compared with those of rAAV1-GFP controls. Serum levels of proinflammatory cytokines such as growth-related oncogene were also significantly higher in the rAAV1-GFP group than in the rAAV1-IL-10 group. These data suggest delivery of IL-10 using a rAAV1 vector improves renal function and prolongs graft survival in a rat model of kidney transplant rejection.

Immunolocalization of fibroblast growth factor-1 (FGF-1), its receptor (FGFR-1), and fibroblast-specific protein-1 (FSP-1) in inflammatory renal disease

BACKGROUND

The fibroblast growth factor (FGF) family has functions in development, cell proliferation, migration, and differentiation. While FGF-2 induces fibrosis, the role of FGF-1 in inflammation and fibrosis is less defined. We examined the expression of FGF-1 and FGF receptor (FGFR-1) to determine if renal diseases with varying etiologies of inflammation, including lupus nephritis (LN), acute interstitial nephritis (AIN) and acute rejection superimposed on chronic allograft nephropathy (CAN), showed varying patterns of expression. We also examined the expression of fibroblast-specific protein-1 (FSP-1), which has been linked to epithelial-mesenchymal transition (EMT) and fibrosis, to determine whether it was linked to potential profibrotic and inflammatory FGF-1 mechanisms.

METHODS

Proliferative LN (PLN) (N= 12), nonproliferative lupus nephritis (NPLN) (N= 5), AIN (N= 6), CAN (N= 4), and normal kidneys (N= 3) were studied. FGF, FGFR-1, and FSP-1 were localized by immunohistochemistry, and intensity scored on a 0 to 3+ scale. Double staining with CD68 and separate immunohistochemical staining for CD4 and CD8 with serial sections analysis were done to identify if T lymphocytes or macrophages showed staining for FGF-1 and FGFR-1 or FSP-1.

RESULTS

In normal kidneys, FGF-1 was expressed in mesangial cells (0.67 +/- 0.58), glomerular endothelial (0.67 +/- 0.58), visceral, and parietal epithelial cells (1.67 +/- 0.58). FGFR-1 showed a similar pattern of staining but also was expressed in tubular epithelium, and arterial endothelium and smooth muscle. Expression of FGF-1 was increased over normal in glomerular parenchymal cells only in CAN in podocytes (2.30 +/- 0.58 vs. 3.00 +/- 0.00) (P < 0.05) and parietal epithelial cells (1.67 +/- 0.58 vs. 2.25 +/- 0.50) (P < 0.05). Infiltrating glomerular and interstitial inflammatory cells in diseased glomeruli also expressed FGF-1 and FGFR-1. Tubular cells expressed slightly increased FGFR-1 in renal diseases vs. normal, whereas tubules remained negative for FGF-1 in diseased kidneys. FSP-1 expression was prominent in the interstitium in all kidneys with interstitial inflammation, and most prominent in CAN. Interstitial FSP-1+ cells were consistent with a myofibroblast-type morphology, and did not stain with CD-68. FSP-1 expression was closely associated with inflammatory cells expressing FGF-1 and FGFR-1. FSP-1 also showed positivity within crescents and occasional podocytes in PLN.

CONCLUSION

The expression of FGF-1 and FGFR-1 in infiltrating lymphocytes and macrophages, and of FGFR-1 in tubules, is supportive, but does not prove causality, of the possibility that FGF-1 might have both autocrine and paracrine functions in renal inflammation. However, the initial stimulus for renal inflammation, whether immune complex, hypersensitivity or rejection, did not alter expression patterns of FGF-1 or its receptor. The colocalization of inflammatory infiltrates with interstitial fibrosis supports the possibility of a contribution of FGF-1 for chemotaxis and associated fibrosis, further supported by interstitial FSP-1 expression closely associated with these inflammatory cells expressing FGF-1 and FGFR-1.