Vitamin D Merging into Immune System-Skeletal Muscle Network: Effects on Human Health

Abstract

The concept that extra-skeletal functions of vitamin D impact on human health have taken place since quite ago. Among all, the beneficial effects of vitamin D on immune regulation, skeletal muscle function, and metabolism are undeniable. Adequate vitamin D levels maintain the immune system and skeletal muscle metabolism integrity, promoting whole-body homeostasis; hypovitaminosis D associates with the important decline of both tissues and promotes chronic inflammation, which is recognized to underlie several disease developments. Growing evidence shows that the immune system and skeletal muscle reciprocally dialogue, modulating each other’s function. Within this crosstalk, vitamin D seems able to integrate and converge some biomolecular signaling towards anti-inflammatory protective effects. Thus, vitamin D regulation appears even more critical at the immune system-muscle signaling intersection, rather than at the single tissue level, opening to wider/newer opportunities in clinical applications to improve health. This paper aims to focus on the immune system-skeletal muscle interplay as a multifaceted target for vitamin D in health and disease after recalling the main regulatory functions of vitamin D on those systems, separately. Some myokines, particularly relevant within the immune system/skeletal muscle/vitamin D networking, are discussed. Since vitamin D supplementation potentially offers the opportunity to maintain health, comments on this issue, still under debate, are included.

The Role of Estrogens and Vitamin D in Cardiomyocyte Protection: A Female Perspective

“…It should be kept in mind that vitamin D is a molecule with quite a special identity, presenting features typical of a nutrient, a hormone and a rapid regulating factor; it is able to affect human health through a fine-tuned regulation of cell functions, by actively participating in biomolecule networking, as recently reported [ 80 , 81 , 82 ].…”

Vitamin D Restores Skeletal Muscle Cell Remodeling and Myogenic Program: Potential Impact on Human Health

“…Supplementation, in fact, potentially represents the necessary intervention to reduce the risk of low vitamin D-induced pathologic status, including skeletal muscle diseases. Remarkably, it must be recalled that the good health of skeletal muscle promotes and supports a good general health status [ 11 , 12 ]. The required doses for supplementation likely depend on the need to respond to skeletal/extra-skeletal needs.…”

“…The biology and function of striated cells, despite low VDR expression, are exquisitely regulated by vitamin D, within either physiologic or pathologic contexts [ 6 , 7 , 8 , 9 , 10 ]. A wide spectrum of findings highlights the link between vitamin D deficiency and increase of skeletal muscle cell wasting, which turns into loss of tissue integrity/function, and, finally, ends in disease development [ 6 , 11 , 12 ]. Importantly, proper skeletal muscle cell remodeling is fully recognized as a key process to warrant tissue adaptation, recovery, and homeostasis [ 13 , 14 ], highly impacting general health status.…”