Fenretinide Corrects Newly Found Ceramide Deficiency in Cystic Fibrosis

Abstract

Chronic and persistent lung infections cause the majority of morbidity and mortality in patients with cystic fibrosis (CF). Galactosyl ceramide has been previously shown to be involved in Pseudomonas internalization. Therefore, we assessed ceramide levels in the plasma of patients with CF and compared them to healthy volunteers using high-performance liquid chromatography followed by mass spectrometry. Our results demonstrate that patients with CF display significantly lower levels of several ceramide sphingolipid species, specifically C14:0, C20:1, C22:0, C22:1, and C24:0 ceramides, and dihydroxy ceramide (DHC16:0). We report that Cftr-knockout mice display diminished ceramide levels in CF-related organs (lung, pancreas, ileum, and plasma) compared with their littermate controls. Since it has been previously reported that in vitro treatment with fenretinide induced ceramide in neuroblastoma cell lines, we decided to test this drug in vivo using our Cftr-knockout mice in an attempt to correct this newly identified defect in ceramide levels. We demonstrate that treatment with fenretinide is able to increase ceramide concentrations in CF-related organs. We further assessed the biological effect of fenretinide on the ability of Cftr-knockout mice to combat lung infection with P. aeruginosa. Our data show dramatic improvement in the ability of Cftr-knockout mice to control P. aeruginosa infection. Overall, these findings not only document a novel deficiency in several ceramide species in patients with CF, but also demonstrate a pharmacologic means to correct this defect in Cftr-knockout mice. Our data provide a strong rationale for clinical intervention that may benefit patients with CF suffering from CF lung disease.

Defective CFTR increases synthesis and mass of sphingolipids that modulate membrane composition and lipid signaling

“…Global gene expression and proteomic analyses have not identified a distinct pathway but revealed that defective CFTR results in upregulation of genes and proteins involved in protein ubiquitination, mitochondrial oxidoreductase activity, and lipid metabolism and implicated defects in the NFkB, lipid, and HSP70 systems (6)(7)(8). More recently, defective CFTR has been associated with altered sphingolipid patterns and metabolism (9)(10)(11)(12).…”

“…Two different groups recently investigated ceramide mass in different CF mouse models, yet came to opposite conclusions whether absence of wild-type CFTR increases or decreases ceramide mass (11,12). The group that found significantly increased plasma and tissue ceramide levels in mice older than 16 weeks had investigated several different CFTR 2/2 mouse models (12).…”

“…Intraperitoneal treatment with amitryptiline, a cationic amphiphile that disrupts lysosomal function resulting in proteolytic degradation of acid ceramidase as well as sphingomyelinase, decreased pulmonary ceramide and prevented all pathological findings, including increased susceptibility to infection (12). The other group found decreased ceramide in plasma, lung, ileum, and pancreas in a complete CFTR knockout model and decreased levels in heterozygote animals (11). In contrast to the studies that found increased ceramide mass, mice found to have decreased ceramide were complete CFTR knockouts that necessitate a special diet, such as Peptamen, to avoid intestinal obstruction.…”

“…It was observed that this diet can reduce ceramide levels and inhibit acid sphingomyelinase by inducing a 3-fold increase of cholesterol in the lungs of CFTRdeficient mice (12). Specific mechanisms for decreased ceramide mass were not evaluated in the study that found decreased ceramide mass, but analysis of plasma from eight CF patients that express the DF508CFTR mutation and two patients with a non-DF508CFTR genotype also showed a decrease in the average mass of total ceramide plasma and noted a decrease of select ceramide species (11). Administration of fenretinide increased ceramide levels and was associated with a significantly increased ability to combat infection and, in a consecutive study, to prevent the development of osteoporosis that characterizes CF (11,19).…”

Cystic fibrosis: the conductance regulator, ceramides, and possible treatments

“…The possibility has been raised that interfering with sphingolipids could be of therapeutic relevance in CF patients [6]. Indeed, fenretinide (4-hydroxy phenylretinamide) is a synthetic retinoid derivative, related to vitamin A. Fenretinide has been investigated for potential use in the treatment of cancer, rheumatoid arthritis, acne, psoriasis, and CF [7]. In an earlier study, Mcilroy et al showed that fenretinide-mediated retinoic acid receptor signaling and inhibition of ceramide biosynthesis regulates adipogenesis, lipid accumulation, mitochondrial function, and nutrient stress signaling in adipocytes and adipose tissue.…”