Acceleration of Regeneration of the Corneal Endothelial Layer After Descemet Stripping Induced by the Engineered FGF TTHX1114 in Human Corneas in Organ Culture

PURPOSE

Descemet stripping only (DSO, descemetorhexis without endothelial keratoplasty) is increasing in clinical use but can impose long recovery times. The objective of this research was to determine whether TTHX1114, an engineered analog of FGF1, could accelerate healing in corneas after DSO.

METHODS

Corneas obtained from eye banks were placed into suspension culture and subjected to DSO with a procedure comparable with that used clinically. The healing of the stripped area and the regeneration of the corneal endothelial cell (CEC) layer were evaluated intermittently for 14 days using trypan blue staining, alizarin red staining, and immunohistochemistry.

RESULTS

Corneas subjected to DSO showed about 30% of the stripped area healed after 14 days in culture while those treated with TTHX1114 healed 81%. The healed area was similar in both normal corneas and corneas judged by the eye banks to be dystrophic. The regeneration of the endothelial layer in the stripped area was substantially more complete in TTHX1114-treated corneas, most of which demonstrated a contiguous monolayer of CECs expressing ZO-1 at the cell-cell junctions. In corneas not subject to DSO, incorporation of EdU, a marker of proliferation, was stimulated by TTHX1114 treatment.

CONCLUSIONS

The corneal organ culture model recapitulated clinical observations of DSO, only with much more rapid recovery. Within the immediate postsurgical time frame of 2 weeks, treatment with TTHX1114 stimulated near-total regeneration of the CEC layer, suggesting that TTHX1114 may be useful as an adjunct to DSO.

Fibroblast growth factors in control of lipid metabolism: from biological function to clinical application

PURPOSE OF REVIEW

Several members of the fibroblast growth factor (FGF) family have been identified as key regulators of energy metabolism in rodents and nonhuman primates. Translational studies show that their metabolic actions are largely conserved in humans, which led to the development of various FGF-based drugs, including FGF21-mimetics LY2405319, PF-05231023, and pegbelfermin, and the FGF19-mimetic NGM282. Recently, a number of clinical trials have been published that examined the safety and efficacy of these novel therapeutic proteins in the treatment of obesity, type 2 diabetes (T2D), nonalcoholic steatohepatitis (NASH), and cholestatic liver disease. In this review, we discuss the current understanding of FGFs in metabolic regulation and their clinical potential.

RECENT FINDINGS

FGF21-based drugs induce weight loss and improve dyslipidemia in patients with obesity and T2D, and reduce steatosis in patients with NASH. FGF19-based drugs reduce steatosis in patients with NASH, and ameliorate bile acid-induced liver damage in patients with cholestasis. In contrast to their potent antidiabetic effects in rodents and nonhuman primates, FGF-based drugs do not appear to improve glycemia in humans. In addition, various safety concerns, including elevation of low-density lipoprotein cholesterol, modulation of bone homeostasis, and increased blood pressure, have been reported as well.

SUMMARY

Clinical trials with FGF-based drugs report beneficial effects in lipid and bile acid metabolism, with clinical improvements in dyslipidemia, steatosis, weight loss, and liver damage. In contrast, glucose-lowering effects, as observed in preclinical models, are currently lacking.

Regulation of FGF1 gene promoter through transcription factor RFX1

Fibroblast growth factor 1 (FGF1) has been suggested to have an important role in cell growth, proliferation, and neurogenesis. Human FGF1 gene 1B promoter (-540 to +31)-driven green fluorescence (F1BGFP) has been shown to monitor endogenous FGF1 expression. F1BGFP could also be used to isolate neural stem/progenitor cells from embryonic, neonatal, and adult mouse brains or to isolate glioblastoma stem cells (GBM-SCs) from human glioblastoma tissues. Here, we present evidence that transcription factor RFX1 could bind the 18-bp cis-elements (-484 to -467) of the F1B promoter, modulate F1BGFP expression and endogenous FGF1 expression, and further regulate the maintenance of GBM-SCs. These observations were substantiated by using yeast one-hybrid assay, electrophoretic mobility shift assay, chromatin immunoprecipitation assay, gain- and loss-of-function assays, and neurosphere assays. Overexpression of RFX1 was shown to down-regulate FGF-1B mRNA expression and neurosphere formation in human glioblastoma cells, whereas RNA interference knockdown of RFX1 demonstrated the opposite effects. Our findings provide insight into FGF1 gene regulation and suggest that the roles of FGF1 and RFX1 in the maintenance of GBM-SCs. RFX1 may negatively regulate the self-renewal of GBM-SCs through modulating FGF-1B and FGF1 expression levels by binding the 18-bp cis-elements of the F1B promoter.

Structure of rat acidic fibroblast growth factor at 1.4 A resolution

Fibroblast growth factors (FGFs) constitute a family of 22 structurally related heparin-binding polypeptides that are involved in the regulation of cell growth, survival, differentiation and migration. Here, a 1.4 A resolution X-ray structure of rat FGF1 is presented. Two molecules are present in the asymmetric unit of the crystal and they coordinate a total of five sulfate ions. The structures of human, bovine and newt FGF1 have been published previously. Human and rat FGF1 are found to have very similar structures.