Fatty acid metabolism is involved in both retinal physiology and the pathology of retinal vascular diseases

FABP4 Is an Indispensable Factor for Regulating Cellular Metabolic Functions of the Human Retinal Choroid

“…Furthermore, IPA analysis of RNA sequencing suggested that visual transduction-related roles were related to FABP4 in the HOCF cells in the top five canonical pathways. In our preceding study, we showed significant increases in both a- and b-waves of ERG amplitudes in Fabp4 −/− mice compared with those in WT mice [ 15 ]. We also found that positive immunoreactivities against FABP4 were detected in most of retinal segments except the photoreceptor outer segment (OS) [ 15 ].…”

“…In the field of ophthalmology, we have comprehensively demonstrated that FABP4 is also present in vitreous fluid and that levels of FABP4 are significantly increased in patients with retinal vascular diseases (RVDs) such as proliferative diabetic retinopathy (PDR) [ 9 ] and retinal vein occlusion (RVO) [ 10 ], which are representative vision-threatening retinal complications of DM, HT and HL [ 11 , 12 , 13 , 14 ]. In addition, we also showed that levels of total fatty acids (FAs) in vitreous fluids are significantly elevated in RVD patients compared with levels in non-RVD patients [ 15 ]. Interestingly, levels of FAs in vitreous fluids were significantly correlated with levels of vitreous FABP4, whereas levels of FAs, vascular endothelial growth factor (VEGFA) and FABP4 in vitreous fluids were not correlated with their plasma levels [ 15 ].…”

“…In addition, we also showed that levels of total fatty acids (FAs) in vitreous fluids are significantly elevated in RVD patients compared with levels in non-RVD patients [ 15 ]. Interestingly, levels of FAs in vitreous fluids were significantly correlated with levels of vitreous FABP4, whereas levels of FAs, vascular endothelial growth factor (VEGFA) and FABP4 in vitreous fluids were not correlated with their plasma levels [ 15 ]. Based on these collective results, it has been speculated that FABP4 is independently involved in the molecular pathogenesis of these RVDs with VEGFA, which is recognized as the most critical pathogenic factor for RVDs, and thus, we have suggested that FABP4 is a rationally promising therapeutic target other than VEGFA.…”

“…Since there were still limited information on the extent of the involvement of FABP4 in RVD etiology and several unsolved questions, including the origin of the intraocular FABP4 despite no fatty tissues being intraocularly present, we have assessed the expression sites of the FABP family in the intraocular tissues in human retinas, wild-type (WT) rat and mouse retinas and in those in DR and retinitis pigmentosa (RP) models by immunolabeling. In these projects, we found that FABP3, 4, 7 and 8 are expressed in the human retina, but only FABP4 and 12 are expressed in rodent retinas, and the immunolabeling patterns of FABP4 for WT, DR and RP rodent retinas are different [ 15 ]. Furthermore, amplitudes of electroretinograms (ERGs) of FABP4-deficient (Fabp4 −/− ) mice were significantly increased in comparison with those of WT mice [ 15 ].…”

“…In these projects, we found that FABP3, 4, 7 and 8 are expressed in the human retina, but only FABP4 and 12 are expressed in rodent retinas, and the immunolabeling patterns of FABP4 for WT, DR and RP rodent retinas are different [ 15 ]. Furthermore, amplitudes of electroretinograms (ERGs) of FABP4-deficient (Fabp4 −/− ) mice were significantly increased in comparison with those of WT mice [ 15 ]. These findings strongly suggest that intraocular FABP4 plays roles in physiological functions such as phototransduction.…”