A 'vaccine' for vision? DHA and metabolites may offer vision protection
Writing in the journal Cellular and Molecular Neurobiology, the team behind the study report that the omega-3 components not only protects cells critical to vision from potentially lethal initial insults, but also from those that occur in the future.
"Our findings support the proposed concept that DHA and docosanoids (molecules made in the brain at the onset of injury or disease) are responsible for activating sustained cellular mechanisms that elicit long-term preconditioning protection," said Professor Nicolas Bazan, MD, PhD, Director of LSU Health New Orleans Neuroscience Center of Excellence.
According to the authors, this pre-conditioning (PC) stimulus is a sub-lethal or pharmacologic stressor that activates a protective response to a future lethal stimulus. This can occur, for example, if the blood supply to an organ is interrupted for a short time and then re-established.
In this case, there is a protective response from that first injury which would carry over to a subsequent blood supply shortage –much like the immunity a vaccine confers against future exposures to disease, suggested Bazan and colleagues.
"This happens in the heart, brain and retina, as well as other organs," he said. "To harness the therapeutic potential of preconditioning, it is very important to identify the molecules directly involved."
Is DHA the key?
The team noted that fish oil contains two types of polyunsaturated fatty acids (PUFAs) which have distinctly different actions: Omega-3s, such as docosahexaenoic acid (DHA) and omega-6s like arachidonic acid (AA).
DHA and its metabolic derivatives, docosanoids, have been shown to possess potent anti-inflammatory and pro-resolving properties, said the team. Meanwhile omega-6 fatty acids and their derivatives have been widely suggested to be pro-inflammatory.
Bazan and his team found that although they are often released in tandem, DHA can alter the action of AA.
Furthermore, when they supplemented DHA prior to an oxidative stress insult, the synthesis of protective DHA derivatives increased while AA synthesis decreased over time.
"Our findings demonstrate that DHA and the induction of docosanoid synthesis is necessary for preconditioning protection, and thus daily survival, of photoreceptor and RPE cells," the lead researcher commented.
"Since omega-3 impairments are associated with neuro-inflammation, which contributes to photoreceptor cell dysfunction and death, enhancing the synthesis of docosanoids may provide an opportunity for halting or ameliorating debilitating retinal degenerative diseases, such as the dry form of age-related macular degeneration," he concluded.
Source: Cellular and Molecular Neurobiology
Published online, Open Access, doi: 10.1007/s10571-017-0565-2
“Retinal Pigment Epithelium and Photoreceptor Preconditioning Protection Requires Docosanoid Signaling”
Authors: Eric J. Knott, et al