The potential efficacy of ω-3 fatty acids as anti-angiogenic agents in benign vascular tumors of infancy

Fatty acids and evolving roles of their proteins in neurological, cardiovascular disorders and cancers

The dysregulation of fat metabolism is involved in various disorders, including neurodegenerative, cardiovascular, and cancers. The uptake of long-chain fatty acids (LCFAs) with 14 or more carbons plays a pivotal role in cellular metabolic homeostasis. Therefore, the uptake and metabolism of LCFAs must constantly be in tune with the cellular, metabolic, and structural requirements of cells. Many metabolic diseases are thought to be driven by the abnormal flow of fatty acids either from the dietary origin and/or released from adipose stores. Cellular uptake and intracellular trafficking of fatty acids are facilitated ubiquitously with unique combinations of fatty acid transport proteins and cytoplasmic fatty acid-binding proteins in every tissue. Extensive data are emerging on the defective transporters and metabolism of LCFAs and their clinical implications. Uptake and metabolism of LCFAs are crucial for the brain's functional development and cardiovascular health and maintenance. In addition, data suggest fatty acid metabolic transporter can normalize activated inflammatory response by reprogramming lipid metabolism in cancers. Here we review the current understanding of how LCFAs and their proteins contribute to the pathophysiology of three crucial diseases and the mechanisms involved in the processes.

Omega-3 Fatty Acids and Their Role in Pediatric Cancer

BACKGROUND

Malnutrition is common in children with cancer and is associated with adverse clinical outcomes. The need for supportive care is becoming ever more evident and the role of nutrition in oncology is still not sufficiently understood. In particular, the consequences of macro- and micronutrient deficiencies require further research. As epidemiological data suggest anti-tumoral properties of omega-3 (n-3) polyunsaturated fatty acids (PUFAs), we reviewed the role of nutrition and n-3 supplementation in pediatric oncology.

METHODS

A comprehensive literature search was conducted on PubMed through 5 February 2021 to select meta-analyses, systematic reviews, observational studies, and individual randomized controlled trials (RCTs) on macro- and micronutrient supplementation in pediatric oncology. The search strategy included the following medical subject headings (MeSH) and keywords: "childhood cancer", "pediatric oncology", "nutritional status", "malnutrition", and "omega-3-fatty-acids". The reference lists of all relevant articles were screened to include potentially pertinent studies.

RESULTS

We summarize evidence about the importance of adequate nutrition in childhood cancer and the role of n-3 PUFAs and critically interpret findings. Possible effects of supplementation on the nutritional status and benefits during chemotherapy are discussed as well as strategies for primary and secondary prevention.

CONCLUSION

We here describe the obvious benefits of omega-3 supplementation in childhood cancer. Further large scale clinical trials are required to verify potential anti-cancer effects of n-3 fatty acids.

Maternal dietary fatty acids and their roles in human placental development

Fatty acids are essential for feto-placental growth and development. Maternal fatty acids and their metabolites are involved in every stage of pregnancy by supporting cell growth and development, cell signaling, and modulating other critical aspects of structural and functional processes. Early placentation process is critical for placental growth and function. Several fatty acids modulate angiogenesis as observed by increased tube formation and secretion of angiogenic growth factors in first-trimester human placental trophoblasts. Long-chain fatty acids stimulate angiogenesis in these cells via vascular endothelium growth factor (VEGF), angiopoietin-like protein 4 (ANGPTL4), fatty acid-binding proteins (FABPs), or eicosanoids. Inadequate placental angiogenesis and trophoblast invasion of the maternal decidua and uterine spiral arterioles leads to structural and functional deficiency of placenta, which contributes to preeclampsia, pre-term intrauterine growth restriction, and spontaneous abortion and also affects overall fetal growth and development. During the third trimester of pregnancy, placental preferential transport of maternal plasma long-chain polyunsaturated fatty acids is of critical importance for fetal growth and development. Fatty acids cross the placental microvillous and basal membranes by mainly via plasma membrane fatty acid transport system (FAT, FATP, p-FABPpm, & FFARs) and cytoplasmic FABPs. Besides, a member of the major facilitator superfamily-MFSD2a, present in the placenta is involved in the supply of DHA to the fetus. Maternal factors such as diet, obesity, endocrine, inflammation can modulate the expression and activity of the placental fatty acid transport activity and thereby impact feto-placental growth and development. In this review, we discuss the maternal dietary fatty acids, and placental transport and metabolism, and their roles in placental growth and development.

Epitheloid hemangioma treated with naproxen sodium

Epitheloid hemangioma (EH) is a vascular tumor characterized by an epithelioid endothelial cell. Predominantly affecting the head and neck, fewer than 30 cases involving the scrotum have been published. As this represents an extremely rare entity, a multitude of anecdotal treatment modalities have been utilized including systemic/intralesional steroid therapy, radiotherapy, and chemical therapy. However, surgical excision remains the most widely accepted treatment option.We present a case of EH of the scrotum in a 14-year-old male patient that regressed after treatment with naproxen sodium. To the best of our knowledge, this represents the first reported case of scrotal EH regression following treatment with naproxen sodium.

LEVEL OF EVIDENCE

V.

Infantile haemangiomas: a challenge in paediatric dermatology

Infantile haemangiomas, common benign vascular tumours of childhood, are characterized by rapid growth during the first year of life and a slow regression that is usually completed at 7-10 years of age. These tumours are composed of endothelial cells with high mitotic rates and stromal components such as fibroblasts, mast cells and pericytes. Haemangiomas become a challenge when they are part of a syndrome, are located in certain areas of the body or when complications develop. The above-mentioned factors also influence the treatment modality used. However, although there remain many uncertainties regarding management, the beta-adrenergic receptor blocker propranolol is a promising new candidate for first-line systemic therapy. It produces such a dramatic and rapid response that the appearance of an infantile haemangioma should impart expeditious consideration of the risks and benefits of its use.

Anti-angiogenesis effect of the novel anti-inflammatory and pro-resolving lipid mediators

PURPOSE

Resolvins and lipoxins are lipid mediators generated from essential polyunsaturated fatty acids that are the first dual anti-inflammatory and pro-resolving signals identified in the resolution phase of inflammation. Here the authors investigated the potential of aspirin-triggered lipoxin (LX) A4 analog (ATLa), resolving (Rv) D1, and RvE1, in regulating angiogenesis in a murine model.

METHODS

ATLa and RvE1 receptor expression was tested in different corneal cell populations by RT-PCR. Corneal neovascularization (CNV) was induced by suture or micropellet (IL-1 beta, VEGF-A) placement. Mice were then treated with ATLa, RvD1, RvE1, or vehicle, subconjunctivally at 48-hour intervals. Infiltration of neutrophils and macrophages was quantified after immunofluorescence staining. The mRNA expression levels of inflammatory cytokines, VEGFs, and VEGFRs were analyzed by real-time PCR. CNV was evaluated intravitally and morphometrically.

RESULTS

The receptors for LXA4, ALX/Fpr-rs-2 and for RvE1, ChemR23 were each expressed by epithelium, stromal keratocytes, and infiltrated CD11b(+) cells in corneas. Compared to the vehicle-treated eye, ATLa-, RvD1-, and RvE1-treated eyes had reduced numbers of infiltrating neutrophils and macrophages and reduced mRNA expression levels of TNF-alpha, IL-1 alpha, IL-1 beta, VEGF-A, VEGF-C, and VEGFR2. Animals treated with these mediators had significantly suppressed suture-induced or IL-1 beta-induced hemangiogenesis (HA) but not lymphangiogenesis. Interestingly, only the application of ATLa significantly suppressed VEGF-A-induced HA.

CONCLUSIONS

ATLa, RvE1, and RvD1 all reduce inflammatory corneal HA by early regulation of resolution mechanisms in innate immune responses. In addition, ATLa directly inhibits VEGF-A-mediated angiogenesis and is the most potent inhibitor of NV among this new genus of dual anti-inflammatory and pro-resolving lipid mediators.

Ccl2/Cx3cr1-deficient mice: an animal model for age-related macular degeneration

BACKGROUND/AIMS

Senescent Ccl2-/- mice develop cardinal features of human age-related macular degeneration (AMD). Loss-of-function single-nucleotide polymorphisms within CX3CR1 are associated with AMD.

METHODS

We generated Ccl2-/-/Cx3cr1-/- [double-knockout (DKO)] mice and evaluated the eyes using fundoscopy routine histology, immunochemistry, biochemistry and proteomics.

RESULTS

At 6 weeks old, all DKO mice developed AMD-like retinal lesions such as abnormal retinal pigment epithelium cells, drusen, photoreceptor atrophy and choroidal neovascularization, which progressed with age and reversed with high omega-3 long-chain polyunsaturated fatty acid diet. N-retinylidene-N-retinylethanolamine (A2E), a major lipofuscin fluorophore, illustrated by an emission peak at approximately 600 nm, was significantly higher in DKO retinal pigment epithelium. Decreased ERp29 was found in the retina of DKO mice.

CONCLUSION

A broad spectrum of AMD pathologies with early onset and high penetrance in these mice implicate certain chemokines, A2E and endoplasmic reticulum proteins in AMD pathogenesis.

Anti-angiogenic effects of conjugated docosahexaenoic acid in vitro and in vivo

The anti-angiogenic effects of conjugated docosahexaenoic acid (CDHA), which was prepared by an alkaline treatment of docosahexaenoic acid and contained conjugated double bonds, were investigated in vitro and in vivo. CDHA inhibited tube formation by the bovine aortic endothelial cell (BAEC), and also inhibited the proliferation of BAEC at a concentration of CDHA that suppressed tube formation, but did not influence cell migration. The inhibition of BAEC growth caused by CDHA was accompanied by a marked change in cellular morphology. Nuclear condensation and brightness were observed in Hoechst 33342-stained cells treated with CDHA, indicating that CDHA induced apoptosis in BAEC. We also evaluated the angiogenesis inhibition of CDHA in vivo. The vessel formation which was triggered by tumor cells was clearly suppressed in mice orally given CDHA. Our findings suggest that CDHA has potential use as a therapeutic dietary supplement for minimizing tumor angiogenesis.

Retinal and choroidal microangiopathies: therapeutic opportunities

Pathological angiogenesis in the retina and underlying choroid is a major cause of visual impairment in all age groups. The last decade has seen an explosion in the clinical availability of antiangiogenic compounds. Emphasis has been placed on inhibitors of the VEGF signaling pathway and considerable success has been achieved with aptamers and antibodies that bind VEGF. However, regression of neovascularization is rarely permanent and the regrowth of new vessels, often within a few months, requires multiple applications of drug. A number of antiangiogenic factors such as IGFBP3, SDF-1 blockers, PEDF, gamma-secretase, Delta-like ligand 4, and integrin antagonists have been identified, which act either indirectly on the VEGF system or independent of it. The importance of other candidates such as HIF-1alpha and protein kinase CK2, which act as "master" regulators of angiogenesis, offer realistic alternative targets for pharmacological intervention. The concept of combination therapy is rapidly gaining interest in the eye field and co-administration of two angiogenic agents (e.g., a CK2 inhibitor with a somatostatin analog, octreotide) are often significantly more effective at inhibiting retinal angiogenesis than either drug alone. The following review will discuss the current therapies available for aberrant ocular angiogenesis, consider new candidate targets for development of antiangiogenic compounds and emphasize the importance of combinatorial pharmacological agents in the treatment of such a dynamic cellular event as angiogenesis.

Immune response: A possible role in the pathophysiology of hemangioma

Hemangioma is a distinct category of benign vascular tumors characterized by presentation within the first weeks of life, rapid growth during the first year and variable degree of spontaneous involution over a period of several years. Recent research reported that CD8+ T cells in hemangiomas, and the endothelia of hemangioma uniquely expressed leukocyte marker FCgammaRII and myeloid cell marker. Presence of high levels of indoleamine 2,3-dioxygenase in proliferating hemangiomas and significantly decreasing during involution was also confirmed. Topical application of imiquimod cream, an immune regulator, to proliferating hemangiomas apparently accelerated regression of the lesions. These findings suggest immune response may be involved in the pathogenesis of hemangioma. The endothelia of hemangioma may express various markers to escape the immune surveillance. An immune response may be one of the mechanisms for hemangioma regression. Strategies with systemically or locally applying immune regulator into the tumor may be an applicable way in accelerating the involution of hemangioma.

A postulated role for transcriptional regulator LMO2 in the proliferation and involution of hemangioma

Hemangiomas are common benign vascular tumors distinctive for their perinatal presentation, rapid growth during the first year of life and subsequent slowly involution. Many evidences suggest that hemangiomas are angiogenesis dependent entity. Research also indicated that the endothelium of hemangioma shared molecular phenotype with blood cells. LMO2 is a transcriptional regulator that play an important role in angiogenesis, hematopoiesis and oncogenesis of hematological tumor. It is logical to postulate that LMO2 may play a role in the pathogenesis, proliferating and involution of hemangioma. Therapies directed against LMO2 have potential importance for treatment of hemangioma because of hemangioma's limited localization and the fact that LMO2-associated protein complexes could regulate angiogenesis.

A possible hypoxia-induced endothelial proliferation in the pathogenesis of epithelioid hemangioma

Epithelioid hemangioma is an uncommon benign vascular lesion with distinct clinicopathological characteristics. Histologically, this entity mainly composed of well-formed but often immature vessels lined by epithelioid endothelial cells with prominent chronic inflammatory component. There is considerable controversy whether epithelioid hemangioma is a reactive lesion or a true neoplasm. We postulated that the local hypoxia may play a role in the pathogenesis of this vascular tumor. This local hypoxic condition may caused by many incidences such as congenital vascular malformation or trauma. The hypoxia will lead to the proliferation of endothelial cells and the formation of this vascular tumor, which may lead by putative stimulators VEGF and HIF-1. Hypoxia may also promote endothelial cell proliferation through the renin-angiotensin-aldosterone system. Additionally, the inflammatory cells including eosinophils and mast cells may contribute to the endothelial cell proliferation in EH. Further study investigating the associated factors of hypoxia may lead to new, potentially important insights into epithelioid hemangioma, and might also contribute to novel strategies for the management of this entity.