Metabolic Effects of Inflammation on Vitamin A and Carotenoids in Humans and Animal Models

Abstract

The association between inflammation and vitamin A (VA) metabolism and status assessment has been documented in multiple studies with animals and humans. The relation between inflammation and carotenoid status is less clear. Nonetheless, it is well known that carotenoids are associated with certain health benefits. Understanding these relations is key to improving health outcomes and mortality risk in infants and young children. Hyporetinolemia, i.e., low serum retinol concentrations, occurs during inflammation, and this can lead to the misdiagnosis of VA deficiency. On the other hand, inflammation causes impaired VA absorption and urinary losses that can precipitate VA deficiency in at-risk groups of children. Many epidemiologic studies have suggested that high dietary carotenoid intake and elevated plasma concentrations are correlated with a decreased risk of several chronic diseases; however, large-scale carotenoid supplementation trials have been unable to confirm the health benefits and in some cases resulted in controversial results. However, it has been documented that dietary carotenoids and retinoids play important roles in innate and acquired immunity and in the body's response to inflammation. Although animal models have been useful in investigating retinoid effects on developmental immunity, it is more challenging to tease out the effects of carotenoids because of differences in the absorption, kinetics, and metabolism between humans and animal models. The current understanding of the relations between inflammation and retinoid and carotenoid metabolism and status are the topics of this review.

Treatment Avenues in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Split-gender Pharmacogenomic Study of Gene-expression Modules

“…The involvement of the metabolism of proteins intuitively makes as it is related to the generation of metabolites linked to immunology, specifically inflammation. 62 Therefore, greater endorsement of poor health outcomes, fatigue measures, and sickness impact may be in part from dysfunction in metabolic processes affecting immunologic balance. M41-TNF-a was highly associated with the Vitality, Physical Functioning, Social Functioning, Pain, and Total measures on the SF-36 assessment; the General Fatigue score on the MFI; the Krupp; and the PSQI.…”

Alterations in retinoic acid signaling affect the development of the mouse coronary vasculature

“…RA-signaling is regulated by a complex transport and enzymatic pathway, which controls the levels of available cellular RA (reviewed in (Shannon et al, 2017)). The cellular RA levels are also influenced by the health and nutritional status of the individual, which can affect, the dietary availability, uptake, or tissue storage of retinol and provitamin A carotenoid precursors (Rubin et al, 2017). …”

Recent insights on the role and regulation of retinoic acid signaling during epicardial development

“…STRA6 has also been found to be responsible for transferring retinol across the blood-tissue barriers in adults and it is likely involved in the transfer of RBP4-delivered retinol across the placenta (Bouillet et al, 1997;Kelly, Widjaja-Adhi, Palczewski, & von Lintig, 2016;Sapin et al, 2000). In spite of a potential role for serum amyloid A in retinol transport, serum retinol concentrations are still significantly decreased in patients experiencing inflammation because of other potential contributing factors (Rubin, Ross, Stephensen, Bohn, & Tanumihardjo, 2017). In spite of a potential role for serum amyloid A in retinol transport, serum retinol concentrations are still significantly decreased in patients experiencing inflammation because of other potential contributing factors (Rubin, Ross, Stephensen, Bohn, & Tanumihardjo, 2017).…”

“…In addition to RBP4, serum amyloid A can bind retinol with high affinity and was suggested to act as an alternate serum transporter for retinol in situations in which the expression of RBP4 is reduced such as during an acute phase response (Derebe et al, 2014;Rosales, Ritter, Zolfaghari, Smith, & Ross, 1996). In spite of a potential role for serum amyloid A in retinol transport, serum retinol concentrations are still significantly decreased in patients experiencing inflammation because of other potential contributing factors (Rubin, Ross, Stephensen, Bohn, & Tanumihardjo, 2017). A second receptor for RBP4-retinol termed retinol binding protein receptor 2 (RBPR2 or STRA6-like) was found to be expressed by tissues that are devoid of STRA6, such as adult liver and intestine (Alapatt et al, 2013;Bouillet et al, 1997).…”