Effects of 1,25-Dihydroxy vitamin D3 on TNF-α induced inflammation in human chondrocytes and SW1353 cells: a possible role for toll-like receptors

Intra-articular injection of rAAV-hFGF-2 ameliorates monosodium iodoacetate-induced osteoarthritis in rats via inhibiting TLR-4 signaling and activating TIMP-1

Osteoarthritis (OA) is a chronic debilitating degenerative disorder leading to structural, and functional anomaly of the joint. The present study tests the hypothesis that overexpression of the basic fibroblast growth factor (FGF-2) via direct rAAV-mediated gene transfer suppresses monosodium iodoacetate (MIA)-induced knee OA in rats relative to control (reporter rAAV-lacZ vector) gene transfer by intra-articular injection. Rats were treated with 20 μl rAAV-hFGF-2 on weekly basis; on days 7, 14, and 21 after single intra-articular injection of MIA (3 mg/50 μl saline). FGF-2 reduced knee joint swelling and improved motor performance and muscle coordination as evidenced by increased distance travelled, mean speed, rearing frequency in open field test (OFT) as well as fall-off latency in rotarod test together with reduced immobility time in OFT. Moreover, FGF-2 attenuated MIA-related radiological and histological alterations. Indeed, FGF-2 decreased knee joint inflammatory biomarker as demonstrated by reduced mRNA expression of toll like receptor (TLR)-4 and its downstream mediators such as tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β) and high motility group box (HMGB) 1. In parallel, FGF-2 attenuated knee joint degradation biomarkers as reflected by the downregulation of ADAMTS-5 mRNA expression and matrix metalloproteinase 13 (MMP-13) content together with the up-regulation of tissue inhibitor of metalloproteinase (TIMP)-1 mRNA expression. These findings suggest a potential therapeutic role for FGF-2 against MIA-induced knee OA in rats via inhibition of TLR4 signaling and activating TIMP-1, resulting in down-regulation of ADAMTS-5 and MMP-13.

Lactic acid induces fibroblast growth factor 23 (FGF23) production in UMR106 osteoblast-like cells

Endocrine and paracrine fibroblast growth factor 23 (FGF23) is a protein predominantly produced by bone cells with strong impact on phosphate and vitamin D metabolism by targeting the kidney. Plasma FGF23 concentration early rises in kidney and cardiovascular diseases correlating with progression and outcome. Lactic acid is generated in anaerobic glycolysis. Lactic acidosis is the consequence of various physiological and pathological conditions and may be fatal. Since FGF23 production is stimulated by inflammation and lactic acid induces pro-inflammatory signaling, we investigated whether and how lactic acid influences FGF23. Experiments were performed in UMR106 osteoblast-like cells, Fgf23 mRNA levels estimated from quantitative real-time polymerase chain reaction, and FGF23 protein determined by enzyme-linked immunosorbent assay. Lactic acid dose-dependently induced Fgf23 gene expression and up-regulated FGF23 synthesis. Also, Na+-lactate as well as formic acid and acetic acid up-regulated Fgf23. The lactic acid effect was significantly attenuated by nuclear factor kappa-light-chain enhancer of activated B-cells (NFκB) inhibitors wogonin and withaferin A. Lactic acid induces FGF23 production, an effect at least in part mediated by NFκB. Lactic acidosis may, therefore, be paralleled by a surge in plasma FGF23.

A retrospective study of nine patients with progressive pseudorheumatoid dysplasia: to explore early diagnosis and further treatment

OBJECTIVES

Most patients with progressive pseudorheumatoid dysplasia (PPRD) are initially misdiagnosed because of disease rarity and lack of awareness by most clinicians. The purpose of this study was to provide further early diagnostic options and potential treatment to patients with PPRD.

METHODS

A retrospective study was performed by collecting and organizing clinical manifestations, radiographic features, laboratory test results, genetic test outcome, treatment, and follow-up records of the patients with PPRD. Age of diagnosis and genotype-phenotype correlation were further analyzed.

RESULTS

Nine PPRD children with causative CCN6 mutation were included. There were 3 pairs of siblings and 1 patient from inbred family. Five patients were primarily misdiagnosed as juvenile idiopathic arthritis (JIA). The interval between onset of symptoms and definite diagnosis of 8 patients varied from 3.6 to 20 years. Symptoms at the onset included enlarged and stiff interphalangeal joints of the fingers, gait disturbance, or joint pain. Laboratory tests revealed normal range of inflammatory parameters. Radiographic findings disclosed different degrees of abnormal vertebral bodies and epiphyseal enlargement of the interphalangeal joints. After the treatment of calcitriol in 5 patients with low level 25-hydroxyvitamin D3 for around 1.25 years to 1.75 years, 2 patients kept stable, while 3 of them improved gradually.

CONCLUSIONS

Combining the patient's family history, clinical features, normal inflammatory markers, and the characteristic radiographic findings, the clinical diagnosis of PPRD for the patients could be obtained at very early stage of the disease. The patients with PPRD carrying c.624dupA variant in CCN6 may have delayed onset. Underlying vitamin D deficiency should be sought and corrected in patients with PPRD.

Vitamin D3 decreases TNF-α-induced inflammation in lung epithelial cells through a reduction in mitochondrial fission and mitophagy

Previous work has shown an association between vitamin D₃ deficiency and an increased risk for acquiring various inflammatory diseases. Vitamin D₃ can reduce morbidity and mortality in these patients via different mechanisms. Lung inflammation is an important event in the initiation and development of respiratory disorders. However, the anti-inflammatory effects of vitamin D₃ and the underlying mechanisms remained to be determined. The purpose of this study was to examine the effects and mechanisms of action of vitamin D₃ (Vit. D) on the expression of intercellular adhesion molecule-1 (ICAM-1) in vitro and in vivo with or without tumor necrosis factor α (TNF-α) treatment. Pretreatment with Vit. D reduced the expression of ICAM-1 and leukocyte adhesion in TNF-α-treated A549 cells. TNF-α increased the accumulation of mitochondrial reactive oxygen species (mtROS), while Vit. D reduced this effect. Pretreatment with Vit. D attenuated TNF-α-induced mitochondrial fission, as shown by the increased expression of mitochondrial fission factor (Mff), phosphorylated dynamin-related protein 1 (p-DRP1), and mitophagy-related proteins (BCL2/adenovirus E1B 19 kDa protein-interacting protein 3, Bnip3) in A549 cells. Inhibition of DRP1 or Mff significantly decreased ICAM-1 expression. In addition, we found that Vit. D decreased TNF-α-induced ICAM-1 expression, mitochondrial fission, and mitophagy via the AKT and NF-κB pathways. Moreover, ICAM-1 expression, mitochondrial fission, and mitophagy were increased in the lung tissues of TNF-α-treated mice, while Vit. D supplementation reduced these effects. In this study, we elucidated the mechanisms by which Vit. D reduces the expression of adhesion molecules in models of airway inflammation. Vit. D might be served as a novel therapeutic agent for the targeting of epithelial activation in lung inflammation.

Do Interactions of Vitamin D3 and BMP Signaling Hold Implications in the Pathogenesis of Fibrodysplasia Ossificans Progressiva?

PURPOSE OF REVIEW

Fibrodysplasia ossificans progressiva (FOP) is a debilitating rare disease known for episodic endochondral heterotopic ossification (HO) caused by gain-of-function mutations in ACVR1/ALK2. However, disease severity varies among patients with identical mutations suggesting disease-modifying factors, including diet, may have therapeutic implications. The roles of vitamin D₃ in calcium metabolism and chondrogenesis are known, but its effects on BMP signaling and chondrogenesis are less studied. This review attempts to assess the possibility of vitamin D's effects in FOP by exploring relevant intersections of VD₃ with mechanisms of FOP flares.

RECENT FINDINGS

In vitro and in vivo studies suggest vitamin D suppresses inflammation, while clinical studies suggest that vitamin D₃ protects against arteriosclerosis and inversely correlates with non-genetic intramuscular HO. However, the enhancement of chondrogenesis, BMP signaling, and possibly Activin A expression by vitamin D may be more relevant in FOP. There appears to be little potential for vitamin D to reduce HO in FOP, but testing the potential for excess vitamin D to promote HO may be warranted.

Vitamin D's Effect on Immune Function

Ever since its discovery by Windhaus, the importance of the active metabolite of vitamin D (1,25-dihydroxyvitamin D₃; 1,25-(OH)2D₃) has been ever expanding. In this review, the attention is shifted towards the importance of the extra-skeletal effects of vitamin D, with special emphasis on the immune system. The first hint of the significant role of vitamin D on the immune system was made by the discovery of the presence of the vitamin D receptor on almost all cells of the immune system. In vitro, the overwhelming effect of supra-physiological doses of vitamin D on the individual components of the immune system is very clear. Despite these promising pre-clinical results, the translation of the in vitro observations to solid clinical effects has mostly failed. Nevertheless, the evidence of a link between vitamin D deficiency and adverse outcomes is overwhelming and clearly points towards avoidance of vitamin D deficiency especially in early life.