Decreased circulating vitamin D reflects adverse outcomes of hepatitis C virus infection: A systematic review and meta-analysis

Vitamin D and autophagy in knee osteoarthritis: A review

Knee osteoarthritis (KOA), the highly prevalent degenerative disease affecting the joint, perpetually devastates the health of the elderly. Of various mechanisms known to participate in KOA etiology, apoptosis of chondrocytes is widely regarded as the primary cause of cartilage degradation. It has been suggested that the induction of autophagy in chondrocytes could potentially prolong the progression of KOA by modulating intracellular metabolic processes, which may be helpful for ameliorating chondrocyte apoptosis and eventual cartilage degeneration. Autophagy, a physiological process characterized by intracellular self-degradation, has been reportedly implicated in various pathologic conditions including KOA. Interestingly, vitamin D has been shown to regulate autophagy in human chondrocytes through multiple pathways, specifically AMPK/mTOR signaling pathway. This observation underscores the potential of vitamin D as a novel approach for restoring the functionality and survivability of chondrocytes in KOA. Supporting vitamin D's clinical significance, previous studies have demonstrated its substantial involvement in the symptoms and irregular joint morphology observed in KOA patients, strengthening potential therapeutic efficacy of vitamin D in treatment of KOA. Herein, the purpose of this review was to determine the mechanisms underlying the multi-processes of vitamin D implicated in autophagy in several cells including chondrocytes, which would bring unique insights into KOA pathogenesis.

Vitamin D–VDR Novel Anti-Inflammatory Molecules—New Insights into Their Effects on Liver Diseases

There is consistent evidence that vitamin D deficiency is strongly associated with liver dysfunction, disease severity, and poor prognosis in patients with liver disease. Vitamin D and its receptor (VDR) contribute to the regulation of innate and adaptive immune responses. The presence of genetic variants of vitamin D- and VDR-associated genes has been associated with liver disease progression. In our recent work, we summarized the progress in understanding the molecular mechanisms involved in vitamin D–VDR signaling and discussed the functional significance of VDR signaling in specific cell populations in liver disease. The current review focuses on the complex interaction between immune and liver cells in the maintenance of liver homeostasis and the development of liver injury, the interplay of vitamin D and VDR in the development and outcome of liver disease, the role of vitamin D- and VDR-associated genetic variants in modulating the occurrence and severity of liver disease, and the therapeutic value of vitamin D supplementation in various liver diseases. The association of the vitamin D–VDR complex with liver dysfunction shows great potential for clinical application and supports its use as a prognostic index and diagnostic tool.

Health consequences of vitamin D deficiency in the human body

Vitamin D is extremely important for the proper functioning of the body. The most commonly known role of vitamin D is its participation in regulation of calcium-phosphate metabolism and bone mineralization. This role is crucial in the prevention of rickets in children and osteoporosis in the elderly. In recent years, numerous studies have confirmed the pleiotropic effects of vitamin D. Proper vitamin D levels in blood have a positive effect on overall health, thus reducing the risk of many diseases. Vitamin D plays, inter alia, a positive role in some diseases of the gastrointestinal tract (inflammatory bowel disease), nervous system (Parkinson disease, Alzheimer disease), and cardiovascular disease (atherosclerosis). Additionally, its positive protective effect in the case of neoplastic and immunological diseases has been noted. Some studies also confirm the relationship of vitamin D deficiency to obesity and depression. In the event of these diseases, it is possible to prevent disease and support the process of treatment by maintaining appropriate levels of 25(OH)D in the blood. Besides, sufficient blood vitamin D levels reduces the risk of developing respiratory tract infections and suppresses cytokine storm, which is responsible for most COVID-19 deaths.

The aim of the study was to present the current state of knowledge regarding the role of vitamin D in the human body, especially in the context of the impact of its abnormal level on the development of various diseases.