The Role of Alterations in Alpha-Klotho and FGF-23 in Kidney Transplantation and Kidney Donation

High pretransplant FGF23 level is associated with persistent vitamin D insufficiency and poor graft survival in kidney transplant patients

Vitamin D3 (25[OH]D3) insufficiency and fibroblast growth factor 23 (FGF23) elevation are usually attenuated after kidney transplantation (KT). However, elevated FGF23 may be associated with poor graft outcomes and vitamin D insufficiency after KT. This study investigated the effect of pretransplant FGF23 levels on post-KT 25(OH)D3 status and graft outcomes. Serum FGF23 levels from 400 participants of the KoreaN Cohort Study for Outcome in Patients With Kidney Transplantation were measured. Annual serum 25(OH)D3 levels, all-cause mortality, cardiovascular event, and graft survival were assessed according to baseline FGF23 levels. Serum 25(OH)D3 levels were initially increased 1 year after KT (12.6 ± 7.4 vs. 22.6 ± 6.4 ng/mL). However, the prevalence of post-KT vitamin D deficiency increased again after post-KT 3 years (79.1% at baseline, 30.8% and 37.8% at 3 and 6 years, respectively). Serum FGF23 level was decreased 3 years post-KT. When participants were categorized into tertiles according to baseline FGF23 level (low, middle, high), 25(OH)D3 level in the low FGF23 group was persistently low at a median follow-up of 8.3 years. Furthermore, high baseline FGF23 level was a risk factor for poor graft survival (HR 5.882, 95% C.I.; 1.443-23.976, P = 0.013). Elevated FGF23 levels are associated with persistently low post-transplant vitamin D levels and poor graft survival.

Time-Dependent Changes of Klotho and FGF-23 Levels after Kidney Transplantation: Role of Cold Ischemia Time, Renal Function and Graft Inflammation

We investigated the evolution of serum klotho (s-Kl) and FGF-23 during the first two years post-kidney transplantation (KT), considering the cold ischemia time (CIT), glomerular filtration rate (GFR) and graft subclinical inflammation (SCI). We undertook a prospective, cohort, multicenter study of consecutive patients between April 2018 and January 2021 (with follow-up at 24 months). Subgroups were analyzed according to the median CIT (<14 vs. ≥14 h), the median GFR (≤40 vs. >40 mL/min/1.73 m²) and the presence of SCI at month 3. A total of 147 patients were included. s-Kl and fibroblast growth factor-23 (FGF-23) levels were measured at baseline and at months 3, 12 and 24. Graft biopsies (n = 96) were performed at month 3. All patients had low s-Kl levels at month 3. Patients with CIT < 14 h exhibited a significant increase in s-Kl at month 24. In patients with CIT ≥ 14 h, s-Kl at month 3 fell and lower s-Kl levels were seen at month 24. Patients with a GFR > 40 had a lesser decrease in s-Kl at month 3. FGF-23 fell significantly at months 3 and 12 in both GFR groups, a reduction maintained during follow-up. There were significant inter-group differences in s-Kl from months 3 to 24. CIT, GFR at 3 months and SCI were significantly associated with s-KI at month 3. A reduction in s-Kl at month 3 post-KT could be explained by longer CIT and delayed graft function as well as by impaired graft function. Early SCI may regulate s-Kl increase post-KT.

Fibroblast Growth Factor-2 (FGF-2) Expression in Pterygia Using Cell Spot Arrays

Fibroblast growth factor (FGF) is a main regulator of cell differentiation, cell migration and angiogenesis in normal and abnormal conjunctiva epithelia, but specific mechanisms of its aberrant expression are yet to be investigated. In the present study, we investigated FGF-2 protein expression within several pterygia. Using a liquid-based cytology assay, we obtained cell specimens from pterygia and healthy tissues directly from patients. A combination of immunocytochemistry followed by digital image analysis showed significant overexpression of FGF-2 in all the examined pterygia. In 30/60 (50%) cases there were high levels of staining intensity, whereas in the remaining 30/60 (50%) cases there were moderate levels of expression. FGF-2 levels of the control group were significantly lower in comparison with the pterygia group. There was no significant correlation between FGF-2 levels and either sex or location of the pterygium. FGF-2 levels had a significant correlation with morphological characteristics of the pterygia. More specifically, FGF-2 levels were significantly higher in the pterygia with a fleshy morphology. Interestingly, recurrent lesions demonstrated high expression levels. An overexpression of FGF-2 has been observed frequently in pterygia, where it may play a crucial role in determining the lesion’s progression. FGF-2 upregulation correlates with the morphology of pterygia and its tendency to recur. Cell spot analysis based on liquid-based cytology is a simple, yet effective, method for detecting a broad spectrum of protein markers and could be useful in analyzing potential pterygia patient samples.