Annurca Apple Polyphenols Protect Murine Hair Follicles from Taxane Induced Dystrophy and Hijacks Polyunsaturated Fatty Acid Metabolism toward β-Oxidation

Abstract

Chemotherapy-induced alopecia (CIA) is a common side effect of conventional chemotherapy and represents a major problem in clinical oncology. Even months after the end of chemotherapy, many cancer patients complain of hair loss, a condition that is psychologically difficult to manage. CIA disturbs social and sexual interactions and causes anxiety and depression. Synthetic drugs protecting from CIA and endowed with hair growth stimulatory properties are prescribed with caution by oncologists. Hormones, growth factors, morphogens could unwontedly protect tumour cells or induce cancer cell proliferation and are thus considered incompatible with many chemotherapy regimens. Nutraceuticals, on the contrary, have been shown to be safe and effective treatment options for hair loss. We here show that polyphenols from Malus Pumila Miller cv Annurca are endowed with hair growth promoting activity and can be considered a safe alternative to avoid CIA. In vitro, Annurca Apple Polyphenolic Extract (AAE) protects murine Hair Follicles (HF) from taxanes induced dystrophy. Moreover, in virtue of its mechanism of action, AAE is herein proven to be compatible with chemotherapy regimens. AAE forces HFs to produce ATP using mitochondrial β-oxidation, reducing Pentose Phosphate Pathway (PPP) rate and nucleotides production. As consequence, DNA replication and mitosis are not stimulated, while a pool of free amino acids usually involved in catabolic reactions are spared for keratin production. Moreover, measuring the effect exerted on Poly Unsaturated Fatty Acid (PUFA) metabolism, we prove that AAE promotes hair-growth by increasing the intracellular levels of Prostaglandins F2α (PGF2α) and by hijacking PUFA catabolites toward β-oxidation.

Keywords: PUFA; Prostaglandins F2; apple polyphenols; chemotherapy induced alopecia; nutraceuticals; taxanes.

Figure 1

Topical treatment with AAE alters PUFAs metabolome in murine HFs. Schematic cartoon depicting some of the metabolic reactions positively affected by AAE in murine HFs. Green arrowheads indicate reactions stimulated by AAE. Green dots indicate metabolites, whose intracellular concentration resulted increased by AAE. (COX cyclooxygenase; LOX, lipoxygenase; CYP, cytochrome P450; sEH, soluble epoxide hydroxylase; n.e. non enzymatic. The abbreviations of PUFA metabolites as well as their full IUPAC name are shown in Table S1).

Figure 2

AAE protects murine HFs from taxanes induced dystrophy. 12 week old C57BL/6 mice were sacrificed and their skin biopsies incubated in vitro in the absence or in the presence of Docetaxel (700 nM), AAE (400 mg/L) or vehicle. Upon 7 days of ex-vivo culturing, biopsies were fixed and processed for histology. Nuclei were stained with DAPI and HFs classified following morphological criteria. (a,b) Untreated HFs in late Anagen phase; (c,d) HFs treated with Docetaxel showing severe signs of follicular dystrophy (e,f) HFs of mice treated with docetaxel in the presence of AAE appearing less damaged by the treatment with the taxane. Scale bars correspond to 50 μm.

Figure 3

AAE preserves keratin content in murine HFs treated with taxanes. Hair shafts plucked out from mice biopsies treated as in Figure 2 were analysed by SEM-EDX. Morphology of hair shafts extracted from untreated skin biopsies (a) or treated with docetaxel (700 nM; b,c,e,g) and showing signs of hair shaft damage. Morphology of hair shafts extracted from HFs treated with Docetaxel in the presence of AAE (d,f,h) showing signs of hair shaft protection exerted by AAE (Scale bars correspond to 10 μm). (i) SEM-EDX quantitative analysis indicates a decrease in Sulphur content in hairs shafts extracted from HFs treated with taxanes. In the presence of AAE the Sulphur content of hair shafts is partially preserved (mean ± s.e.m.; n = 8, *** p < 0.001).