The Dramatic Role of IFN Family in Aberrant Inflammatory Osteolysis

Enamel Matrix Derivative Suppresses Chemokine Expression in Oral Epithelial Cells

Epithelial cells in periodontitis patients increasingly express chemokines, suggesting their active involvement in the inflammatory process. Enamel matrix derivative (EMD) is an extract of porcine fetal tooth germs clinically applied to support the regrowth of periodontal tissues. Periodontal regeneration might benefit from the potential anti-inflammatory activity of EMD for epithelial cells. Our aim was, therefore, to set up a bioassay where chemokine expression is initiated in the HSC2 oral squamous carcinoma cell line and then test EMD for its capacity to lower the inflammatory response. To establish the bioassay, HSC2 cells being exposed to TNFα and LPS from E. coli (Escherichia coli) or P. gingivalis (Porphyromonas gingivalis) were subjected to RNAseq. Here, TNFα but not LPS caused a robust increase of chemokines, including CXCL1, CXCL2, CXCL8, CCL5, and CCL20 in HSC2 cells. Polymerase chain reaction confirmed the increased expression of the respective chemokines in cells exposed to TNFα and IL-1β. Under these conditions, EMD reduced the expression of all chemokines at the transcriptional level and CXCL8 by immunoassay. The TGF-β receptor type I kinase-inhibitor SB431542 reversed the anti-inflammatory activity. Moreover, EMD-activated TGF-β-canonical signaling was visualized by phosphorylation of smad3 and nuclear translocation of smad2/3 in HSC2 cells and blocked by SB431542. This observation was confirmed with primary oral epithelial cells where EMD significantly lowered the SB431542-dependent expression of CXCL8. In summary, our findings suggest that TGF-β signaling mediates the effects of EMD to lower the forced expression of chemokines in oral epithelial cells.

Interleukin-29 Accelerates Vascular Calcification via JAK2/STAT3/BMP2 Signaling

Background Vascular calcification (VC), associated with enhanced cardiovascular morbidity and mortality, is characterized by the osteogenic transdifferentiation of vascular smooth muscle cells. Inflammation promotes VC initiation and progression. Interleukin (IL)-29, a newly discovered member of type III interferon, has recently been implicated in the pathogenesis of autoimmune diseases. Here we evaluated the role of IL-29 in the VC process and underlying inflammatory mechanisms. Methods and Results The mRNA expression of IL-29 was significantly increased and positively associated with an increase in BMP2 (bone morphogenetic protein 2) mRNA level in calcified carotid arteries from patients with coronary artery disease or chronic kidney disease. IL-29 and BMP2 proteins are colocalized in human calcified arteries. IL-29 binding to its specific receptor IL-28Rα (IL-28 receptor α) (IL-29/IL-28Rα) inhibited the proliferation of rat vascular smooth muscle cells without altering cell apoptosis or migration. IL-29 promoted the calcification of rat vascular smooth muscle cells and their osteogenic transdifferentiation in vitro as well as the rat aortic ring calcification ex vivo, induced by the calcification medium or osteogenic medium. The procalcification effect of IL-29 was reduced by pharmacological inhibition of IL-29/IL-28Rα binding as well as suppression of janus kinase 2/signal transducer and activator of transcription pathway activation, accompanied by decreased BMP2 expression in the cultured rat vascular smooth muscle cells. Conclusions These results suggest an important role of IL-29 in VC development, at least partly, via activating the janus kinase 2/signal transducer and activator of transcription 3 signaling. Inhibition of IL-29 or its specific receptor, IL-28Rα, may provide a novel strategy to reduce VC in patients with vascular diseases.

Dietary inflammatory index and osteoporosis: the National Health and Nutrition Examination Survey, 2017-2018

PURPOSE

The dietary inflammatory index (DII) is a scoring system to quantify the inflammatory effects of nutrients and foods. Inflammation may affect bone health. The purpose of this study was to explore the relationships of DII with bone mineral density (BMD) and osteoporosis.

METHODS

This study involved 1023 women and 1080 men (age ≥ 50) in the US National Health and Nutrition Survey (NHANES), 2017-2018. Multivariable linear regression models were used to estimate the associations between DII and BMD. Association between DII and osteoporosis was tested with multivariable logistic regression models.

RESULTS

In women, DII was negatively associated with total hip and femoral neck BMD after adjusting for covariates (P < 0.05). In men, DII was negatively associated with lumbar spine BMD (P < 0.05). DII was positively associated with osteoporosis in women (P < 0.05). The odds ratios (ORs) (95% CI) for osteoporosis associated with DII quartiles 2, 3 and 4 vs. quartile 1 were 2.95 (1.08, 8.09), 5.63 (2.87, 11.04), and 6.14(2.55, 14.78), respectively. No significant association was observed in men.

CONCLUSIONS

Higher DII scores were associated with increase osteoporosis risk in women, while no association was found in men. Greater pro-inflammatory diets might be associated with lower BMD in both women and men.

Spatial-Temporal Patterns and Inflammatory Factors of Bone Matrix Remodeling

The bone extracellular matrix (ECM) contains organic and mineral constituents. The establishment and degradation processes of ECM connect with spatial and temporal patterns, especially circadian rhythms in ECM. These patterns are responsible for the physical and biological characteristics of bone. The disturbances of the patterns disrupt bone matrix remodeling and cause diverse bone diseases, such as osteogenesis imperfecta (OI) and bone fracture. In addition, the main regulatory factors and inflammatory factors also follow circadian rhythms. Studies show that the circadian oscillations of these factors in bone ECM potentially influence the interactions between immune responses and bone formation. More importantly, mesenchymal stem cells (MSCs) within the specific microenvironments provide the regenerative potential for tissue remodeling. In this review, we summarize the advanced ECM spatial characteristics and the periodic patterns of bone ECM. Importantly, we focus on the intrinsic connections between the immunoinflammatory system and bone formation according to circadian rhythms of regulatory factors in bone ECM. And our research group emphasizes the multipotency of MSCs with their microenvironments. The advanced understandings of bone ECM formation patterns and MSCs contribute to providing optimal prevention and treatment strategies.

Regulatory Role of the RNA N6-Methyladenosine Modification in Immunoregulatory Cells and Immune-Related Bone Homeostasis Associated With Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease for which the etiology has not been fully elucidated. Previous studies have shown that the development of RA has genetic and epigenetic components. As one of the most highly abundant RNA modifications, the N⁶-methyladenosine (m⁶A) modification is necessary for the biogenesis and functioning of RNA, and modification aberrancies are associated with various diseases. However, the specific functions of m⁶A in the cellular processes of RA remain unclear. Recent studies have revealed the relationship between m⁶A modification and immune cells associated with RA. Therefore, in this review, we focused on discussing the functions of m⁶A modification in the regulation of immune cells and immune-related bone homeostasis associated with RA. In addition, to gain a better understanding of the progress in this field of study and provide the proper direction and suggestions for further study, clinical application studies of m⁶A modification were also summarized.