Transforming growth factor-β and diabetic nephropathy

Transforming growth factor-β1 in children with diabetic nephropathy

BACKGROUND

Transforming growth factor-β1 (TGF-β1) is a multifunctional cytokine that has numerous biological processes. Earlier research indicates that protein and mRNA production of TGF-β1 are enhanced in the renal tissues of patients with diabetic nephropathy (DN). Our aim was to evaluate the role of TGF-β1 in early prediction of DN in children with type 1 diabetes mellitus (T1DM).

METHODS

Fifty patients with T1DM were enrolled in an observational study. Patients were eligible to participate if at least 3 years had passed since T1DM diagnosis. Patients were classified into two groups (A and B) according to the presence or absence of microalbuminuria, respectively. Serum TGF-β1 was measured by ELISA in the patients.

RESULTS

Out of the 50 studied patients with T1DM, there were 23 (46%) patients with microalbuminuria. There was a significant difference between patients in group A and B as regards TGF-β1 (p < 0.001). HbA1c had very little influence in controlling for the relationship between TGF-β1 and disease duration. Diagnostic cutoff value of TGF-β1 was 358.5 pg/ml with sensitivity and specificity of 100%.

CONCLUSION

TGF-β1 was significantly higher in children with DN in comparison with children without. It could be used as an early indicator of DN in children with T1DM with high sensitivity and specificity.

Angiotensin II as a morphogenic cytokine stimulating renal fibrogenesis

Inhibitors of the renin-angiotensin-aldosterone system attenuate glomerulosclerosis and interstitial fibrosis. Although the mechanisms underlying their antifibrotic effects are complex, angiotensin II (Ang II) emerges as a major profibrogenic cytokine. Ang II modulates renal cell growth, extracellular matrix synthesis, and degradation by multiple fibrotic pathways. One of the main targets of Ang II in renal fibrosis is TGFβ. Many, but not all, of the stimulatory effects of Ang II on fibrogenesis depend on the induction of TGFβ and its downstream mediators of matrix accumulation, inflammation, and apoptosis. However because of the difficulty in targeting TGFβ, connective tissue growth factor β (CTGF), a downstream mediator of TGFβ, has become a more promising antifibrotic target. Ang II can directly induce expression of renal CTGF and mediate epithelial-mesenchymal transition. Other profibrotic factors stimulated by Ang II include endothelin-1, plasminogen activator inhibitor-1, matrix metalloproteinase (MMP)-2, and a tissue inhibitor of metalloproteinase-2. Finally, connections among Ang II, hypoxia, and the induction of hypoxia-inducible factor-1α contribute to fibrogenesis. A better understanding of the multiple morphogenic effects of Ang II may be necessary to develop better strategies to halt the progression of renal disease.