Association between interleukin-6-174G/C gene polymorphism and asthma severity: exploring the role of total serum IgE, blood eosinophils, and FeNO as markers of type 2 inflammation

BACKGROUND

While a connection has been established between serum interleukin-6 (IL-6) levels and the IL-6 gene (- 174G/C) polymorphism in allergic diseases such as asthma, its specific association with severe asthma remains unexplored. This study examined the relationship between the IL-6 (- 174G/C) gene polymorphism and mild and severe asthma, focusing on its influence on type 2 inflammation.

METHODS

Our study comprised 98 patients with mild asthma and 116 with severe asthma. Additionally, we recruited 121 healthy participants to serve as controls for comparative analyses. The IL-6 gene (- 174G/C) polymorphism was assessed utilizing the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

In our study, the risk of mild asthma exhibited a significant fourfold increase in individuals with the GG genotype pattern compared to healthy controls, yielding an odds ratio (OR) of 4.4 (p < 0.001). Conversely, we found no significant correlation between the IL-6 - 174G/C gene polymorphism and severe asthma when compared to the healthy control group. However, a noteworthy pattern emerged when we compared subgroups of mild and severe asthma. The risk of severe asthma increased fivefold in individuals with the GC polymorphism pattern, with an OR of 4.99 (p < 0.001), while the likelihood of mild asthma showed a similar fourfold increase with the GG polymorphism pattern, OR = 4.4 (p < 0.001). Consequently, we observed a significantly higher frequency of the C allele in patients with severe asthma, whereas the G allele was more prevalent in individuals with mild asthma (p = 0.05). Additionally, the correlation between markers of type 2 inflammation and the dominant model of the IL-6 gene -174G/C polymorphism (CC + CG vs GG) revealed a significant increase in total serum immunoglobulin E (IgE), Blood Eosinophil Counts (BEC), and Fractional Exhaled Nitric Oxide (FeNO) levels in asthmatic patients with the CC + CG gene pattern compared to those with GG, with p-values of 0.04, 0.03, and 0.04, respectively. Furthermore, after adjusting for other risk factors, the likelihood of developing severe asthma increased from fourfold to eightfold, with an OR of 8.12 (p = 0.01) with (CC + CG) gene pattern. Other predictors for severe asthma included older age and childhood-onset disease (OR = 1.13 and 19.19, p < 0.001). Allergic rhinitis (AR) and nasal polyps (NP) also demonstrated a substantial association with an increased risk of severe asthma, with odds ratios of 5 and 32.29 (p = 0.01 and < 0.001), respectively. Additionally, elevated Body Mass Index (BMI), BEC, and FeNO were linked to severe asthma, with ORs of 1.11, 1.00, and 1.04, respectively (p = 0.04, 0.05, and 0.001).

CONCLUSION

This study illuminated the intricate relationship between the IL-6 gene polymorphism, type 2 inflammation markers, and diverse risk factors in shaping asthma severity. As a significant association between the GG polymorphism of the IL-6 gene (- 174G/C) and mild asthma was found, while possessing at least one C allele, whether in a homozygous (CC) or heterozygous (CG) combination, independently predicts the likelihood of severe asthma.

Genetic polymorphisms of interleukin-16 in Egyptian patients with primary knee osteoarthritis

Background

The pro-inflammatory cytokine, interleukin 16 (IL-16), has been shown to be secreted in low levels in knee osteoarthritis (KOA). The aim of the study was to examine the relationship between IL-16 polymorphisms and the risk of KOA in the Egyptian population, as well as the clinical and radiographic severity of KOA.

Results

IL16 rs11556218 thymidine triphosphate (T) T G (guanosine triphosphate), GG, TG + GG genotypes, and G allele (odd ratio (OR) = 0.315; 95% confidence interval (CI) = 0.191–0.518; P < 0.001; OR = 0.363; 95% CI = 0.162–0.815, P = 0.014; OR = 0.323; 95% CI = 0.202–0.519, P < 0.001; OR = 0.480; 95% CI = 0.338–0.683, P < 0.001 respectively); rs4778889 cytidine triphosphate (C) T,CC, TC + CC genotypes, and C allele (OR = 0.519, 95% CI = 0.319–0.844, P = 0.008; OR = 0.309, 95% CI = 0.105–0.916, P = 0.034; OR = 0.485, 95% CI = 0.304–0.775, P = 0.002; OR = 0.537, 95% CI = 0.365–0.791, P = 0.001 respectively); and rs4072111 CT, TT, CT + TT genotypes, and T allele (OR = 0.537, 95% CI = 0.323–0.893, P = 0.017, OR = 0.316, 95% CI = 0.096–0.843, P = 0.049, OR = 0.502, 95% CI = 0.309–0.816, P = 0.005; OR = 0.534, 95% CI = 0.353–0.809, P = 0.004 respectively) were associated with a decreased KOA risk, and they were significantly associated with decreased the Western Ontario and McMaster Universities Arthritis Index (WOMAC) and the Kellgren-Lawrence (K/L) scores.

Neither IL-16 serum levels nor IL-16 polymorphisms were associated with the susceptibility to KOA. Low KOA risk was associated with the haplotypes GTC and TCT.

Conclusion

There was no correlation between serum IL-16 levels and KOA susceptibility or IL-16 polymorphisms. GTC and TCT haplotypes were associated with low KOA risk. The variant alleles rs11556218GG, TG + GG; rs4778889 CC, TC + CC; and rs4072111 TT, CT + TT were associated with a reduced risk of KOA.

Association of rs1800795 and rs1800796 polymorphisms in interleukin-6 gene and osteoarthritis risk: evidence from a meta-analysis

Multiple studies have investigated the association of interleukin-6 (IL-6) gene polymorphisms and osteoarthritis (OA) risk, but failed to reach a consistent conclusion. Therefore, this study was designed to elucidate the association of IL-6 polymorphisms and OA by a meta-analysis approach. Literature retrieval was carried out on PubMed, EMBASE, Web of Science, CNKI, and Wanfang databases. The strength of association was appraised by odds ratios (ORs) and 95% confidence intervals (95%CIs) in five genetic models. The data were merged by using RevMan 5.3 software. Ten studies with 4944 cases and 4651 controls were analyzed. Overall, no significant association was identified between rs1800795 polymorphism and OA. Subgroup analysis by ethnicity and OA site also suggested rs1800795 polymorphism was not associated with OA. For rs1800796 polymorphism, G-allele and GG-genotype carriers appeared to have an increased risk to OA (G vs. C, OR = 1.66, 95%CI 1.30-1.96, P < 0.01; GG vs. CC, OR = 1.75, 95%CI 1.07-2.84, P = 0.03; GG vs. GC + CC, OR = 1.82, 95%CI 1.42-2.34, P < 0.01). Findings of this study indicate that the rs1800795 polymorphism is not correlated to OA susceptibility, regardless of ethnicity or OA site. However, rs1800796 polymorphism trends to be associated with susceptibility to OA.

Association between Common Variants in VEGFA Gene and the Susceptibility of Primary Knee Osteoarthritis

OBJECTIVES

This study aimed to analyze the relationship between vascular endothelial growth factor A (VEGFA) gene polymorphisms, plasma VEGFA, and the susceptibility of knee osteoarthritis (OA).

DESIGN

A total of 404 subjects, 202 knee OA subjects and 202 healthy volunteers, were enrolled into the study. Four distinct polymorphisms of the VEGFA gene were evaluated using polymerase chain reaction-restriction fragment length polymorphism: -2578C/A (rs699947), -1154G/A (rs1570360), -634C/G (rs2010963), and +936C/T (rs3025039). Plasma VEGFA levels were analyzed using enzyme-linked immunosorbent assay.

RESULTS

The most common nucleotides in both knee OA subjects and healthy controls were CC for -2578C/A, GG for -1154G/A, CG for -634C/G, and CC for +936C/T in the VEGFA gene. Genotype distribution and allele frequencies of VEGFA -2578C/A, -1154G/A, -634C/G, and +936C/T single nucleotide polymorphisms did not differ between OA patients and the controls. Plasma VEGFA levels showed no difference between OA patients and the controls. In contrast, plasma VEGFA levels of -634C/C genotype were significantly higher in OA patients than in the controls (P = 0.035). According to the -2578A/A genotype, patients with early stage OA had a higher odds ratio than those with advanced stage OA (P = 0.023).

CONCLUSIONS

VEGFA -2578C/A (rs699947), -1154G/A (rs1570360), -634C/G (rs2010963), and +936C/T (rs3025039) polymorphisms may not be responsible for OA susceptibility in the Thai population. However, the OA patients with A/A genotype at the -2578C/A seemed to have a lower potential risk of developing severe OA than those with the C/A and C/C genotypes. These findings would help elucidate and facilitate a better understanding of the genetic fundamentals of OA.

Effect of IL-6 -174G/C and -572G/C variants on susceptibility to osteoarthritis in Turkish population

Osteoarthritis (OA) is a complex disorder characterized by degenerative articular cartilage in which inflammatory mechanisms play a major role in the pathogenesis. Interleukin-6 (IL6), a multifunctional cytokine, can trigger osteoclast differentiation and bone resorption. Our purpose in this study was to evaluate the association of IL-6 -174 G/C (rs1800795) and -572 G/C (rs1800796) variants with the susceptibility to OA. One hundred fifty OA patients and 150 healthy individuals were enrolled in the study. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) was used for genotyping the IL-6 gene variants. The results of analyses were evaluated for statistical significance. The pain intensity was assessed using the Visual Analogue Scale (VAS). There was a statistically significant difference in the genotype and allele frequencies of the IL-6 -174 G/C variant between patients with OA and control groups (p = 0.001, p = 0.002, respectively). IL-6 -174 G/C GG genotype and G allele were more prevalent in patients with OA. We found that the IL-6 -572 G/C variant was not different between patients and controls in either genotype distribution and allele frequency. IL-6 174 G/C and -572 G/C loci GG-GG combined genotype was significantly higher in OA patients (p = 0.00). Our study suggests that there was a strong association between the IL-6 -174 G/C variant and OA in the Turkish population. Further studies on populations of different ethnic background are necessary to prove the association of IL-6 variants with OA.

Cartilage tissue engineering: From proinflammatory and anti‑inflammatory cytokines to osteoarthritis treatments (Review)

Osteoarthritis (OA), one of the most common joint diseases, is characterized by fibrosis, rhagadia, ulcers and attrition of articular cartilage due to a number of factors. The etiology of OA remains unclear, but its occurrence has been associated with age, obesity, inflammation, trauma and genetic factors. Inflammatory cytokines are crucial for the occurrence and progression of OA. The intra-articular proinflammatory and anti-inflammatory cytokines jointly maintain a dynamic balance, in accordance with the physiological metabolism of articular cartilage. However, dynamic imbalance between proinflammatory and anti-inflammatory cytokines can cause abnormal metabolism in knee articular cartilage, which leads to deformation, loss and abnormal regeneration, and ultimately destroys the normal structure of the knee joint. The ability of articular cartilage to self-repair once damaged is limited, due to its inability to obtain nutrients from blood vessels, nerves and lymphatic vessels, as well as limitations in the extracellular matrix. There are several disadvantages inherent to conventional repair methods, while cartilage tissue engineering (CTE), which combines proinflammatory and anti-inflammatory cytokines, offers a new therapeutic approach for OA. The aim of the present review was to examine the proinflammatory factors implicated in OA, including IL-1β, TNF-α, IL-6, IL-15, IL-17 and IL-18, as well as the key anti-inflammatory factors reducing OA-related articular damage, including IL-4, insulin-like growth factor and TGF-β. The predominance of proinflammatory over anti-inflammatory cytokine effects ultimately leads to the development of OA. CTE, which employs mesenchymal stem cells and scaffolding technology, may prevent OA by maintaining the homeostasis of pro- and anti-inflammatory factors.

Internalization of Neutrophil-Derived Microvesicles Modulates TNFα-Stimulated Proinflammatory Cytokine Production in Human Fibroblast-Like Synoviocytes

Neutrophil-derived microvesicles (NDMVs) have the potential to exert anti-inflammatory effects. Our study aimed to explore the effects of NDMVs on proinflammatory cytokines expressed by tumor necrosis factor α (TNFα)-stimulated fibroblast-like synoviocytes (FLS). FLS were isolated from the synovium of knee osteoarthritis (OA) patients undergoing surgery. NDMVs, isolated from TNFα-stimulated healthy neutrophils, were characterized by electron microscopy and nanoparticle tracking analysis. MTT and scratch wound healing assays were used to measure FLS viability and migration after treatment with NDMVs, while internalization of fluorescently labeled NDMVs was appraised by flow cytometry and confocal microscopy. Levels of proinflammatory cytokines in supernatants were quantified by the Bio-Plex system. Incubation of FLS with NDMVs at a vesicle/cell ratio of 100 resulted in a time-dependent uptake, with 35% of synoviocytes containing microvesicles over a 6–24 h time period, with no significant change in cell viability. TNFα stimulated the cytokine expression in FLS, and NDMVs down-regulated TNFα-induced expression of IL-5, IL-6, IL-8, MCP-1, IFNγ and MIP-1β. However, this down-regulation was selective, as NDMVs had no significant effects on TNFα-stimulated expression of IL-2 or IL-4. NDMVs were internalized by FLS to inhibit TNFα-stimulated broad-spectrum proinflammatory cytokine secretion. NDMVs, therefore, may exhibit an anti-inflammatory role in the regulation of the FLS function.

An insight into osteoarthritis susceptibility: Integration of immunological and genetic background

Osteoarthritis (OA) is a progressive degenerative disease that affects all synovial joints, causing the disability of the main locomotor diarthrodial joints. OA pathogenesis is caused by a complex interplay between a number of genetic and environmental risk factors, involved in the early onset and progression of this chronic inflammatory joint disease. Uncovering the underlying immunological and genetic mechanisms will enable an insight into OA pathophysiology and lead to novel and integrative approaches in the treatment of OA patients, together with a reduction of the disease risk, or a delay of its onset in susceptible patients.

Pathophysiological landscape of osteoarthritis

A sharp rise in osteoarthritis (OA) incidence is expected as over 25% of world population ages in the coming decade. Although OA is considered a degenerative disease, mounting evidence suggests a strong connection with chronic metabolic conditions and low-grade inflammation. OA pathology is increasingly understood as a complex interplay of multiple pathological events including oxidative stress, synovitis and immune responses revealing its intricate nature. Cellular, biochemical and molecular aspects of these pathological events along with major outcomes of the relevant research studies in this area are discussed in the present review. With reference to their published and unpublished work, the authors strongly propose synovitis as a central OA pathology and the key OA pathological events are described in connection with it. Recent research outcomes also have succeeded to establish a linkage between metabolic syndrome and OA, which has been precisely included in the present review. Impact of aging process cannot be neglected in OA. Cell senescence is an important mechanism of aging through which it facilitates development of OA like other degenerative disorders, also discussed within a frame of OA. Conclusively, the reviewers urge low-grade inflammation linked to aging and derailed immune function as a pathological platform for OA development and progression. Thus, interventions targeted to prevent inflammaging hold a promising potential in effective OA management and efforts should be invested in this direction.

Interleukin-34 as a promising clinical biomarker and therapeutic target for inflammatory arthritis

Interleukin-34 (IL-34), recently identified as a novel inflammatory cytokine and the second ligand for colony-stimulating factor-1 receptor, is known to play regulatory roles in the development, maintenance, and function of mononuclear phagocyte lineage cells - especially osteoclasts. Regarding its primary effect on osteoclasts, IL-34 has been shown to stimulate formation and activation of osteoclasts, which in turn magnifies osteoclasts-resorbing activity. In addition to its role in osteoclastogenesis, IL-34 has been implicated in inflammation of synovium via augmenting production of inflammatory mediators, in which altered IL-34 expression is regulated by pro-inflammatory cytokines responsible for cartilage degradation. Indeed, IL-34 has been documented to be highly expressed in inflamed synovium of rheumatoid arthritis (RA) and knee osteoarthritis (OA) patients, which are recognized as inflammatory arthritis. Furthermore, a number of clinical studies demonstrated that IL-34 levels were significantly increased in the circulation and synovial fluid of patients with RA and knee OA. Its levels were also found to be positively associated with disease severity - especially radiographic severity of both RA and knee OA patients. Interestingly, emerging evidence has accumulated that functional blockage of IL-34 with specific antibody can alleviate the severity of inflammatory arthritis. It is therefore reasonable to speculate that IL-34 may be developed as a potential biomarker and a new therapeutic candidate for inflammatory arthritis. To date, there are numerous studies showing IL-34 involvement and association with many aspects of inflammatory arthritis. Herein, this review aimed to summarize the recent findings regarding regulatory role of IL-34 in synovial inflammation-mediated cartilage destruction and update the current comprehensive knowledge on usefulness of IL-34-based treatment in inflammatory arthritis - particularly RA and knee OA.

Interaction between GDF5 gene polymorphisms and environment factors increased the risk of knee osteoarthritis: a case-control study

Using a case–control design, we assessed the association between single nucleotide polymorphisms (SNPs) of growth and differentiation factor 5 (GDF5)/rs143383 gene and interaction with environments and knee osteoarthritis (KOA). We recruited 288 KOA patients from the First Clinical College, Henan University of Chinese Medicine between June 2017 and May 2018. There was significant difference in genotype distribution between case group and control group (χ² = 22.661, P=0.000). The minor C allele was significantly higher in the case group than that in the control group (20.5 vs 8.1%, P=0.000, odds ratio (OR) = 1.62, 95% confidence interval (CI): 1.29–2.03). Significant differences were also observed in other gene models. For age, all models show significant differences (P<0.05) for those whose age was more than 60 years, and no significant difference was observed for those under 60 years. For non-smoking group, there were significant differences between case group and control group, and for smoker, significance level was found in TT compared with CC and allele gene models. Patients with drinking and Bbody mass index (MI )≥ 24 also showed significant relationship between rs143383 and osteoarthritis (OA) under the following models: TT vs CC (P=0.000, P=0.018), TT/CT vs CC (P=0.043), TT vs CT/CC (P=0.000, P=0.009), and T vs C (P=0.024, P=0.000). Other gene models indicated no significance (P>0.05). Our results revealed a possible genetic association between GDF5 and KOA, and the TT genotype of rs143383 increased the risk of KOA in Chinese Han population. The interaction between GDF5 gene and drinking, smoking, and obesity further increased the risk of KOA.

[Effect of intra-articular injection of platelet-rich plasma on interleukin-17 expression in synovial fluid and venous plasma of knee osteoarthritis patients]

Objective

To investigate the interleukin-17 (IL-17) levels changes in both synovial fluid and venous plasma of patients with primary knee osteoarthritis (OA) after intra-articular injection of platelet-rich plasma (PRP).

Methods

Between January 2015 and January 2016, 30 patients with primary knee OA were treated by intra-articular injection of PRP once a week for 3 weeks (trial group). Thirty healthy individuals were recruited into the study as control. There was no significant difference in gender, age, and body mass index between 2 groups ( P>0.05). Visual analogue scale (VAS) score and Knee Society Score (KSS) were used to evaluate pain level and function of the knee for patients with OA. The IL-17 levels in both venous plasma and synovial fluid were measured before injection and at 1, 3, 6, and 12 months after injection in trial group and the IL-17 levels in venous plasma were measured in control group. The levels were determined using ELISA method.

Results

There was no knee joint swelling, fever, local infection, or other uncomfortable symptoms for all patients in process of PRP injection. All patients were followed up 13.5 months on average (range, 12-15 months). In trial group, the VAS scores at different time points after injection were significantly lower than that before injection ( P<0.05). And the KSS scores at different time points after injection were significantly higher than that before injection ( P<0.05). There was no significant difference in VAS and KSS scores between different time points after injection ( P>0.05). The IL-17 levels in venous plasma before and after injection in trial group were significantly higher than that in control group ( P<0.05). The IL-17 levels in venous plasma at each time point after injection were significantly lower than that before injection ( P<0.05). There was no significant difference in IL-17 levels in both venous plasma and synovial fluid between different time points after injection ( P>0.05).

Conclusion

Intra-articular injection of PRP can significantly release the pain symptoms, improve joint function, and reduce IL-17 levels in both synovial fluid and venous plasma of the patients with knee OA, but IL-17 levels can not reduce to normal level.

[Change of inflammatory cytokines levels in both synovial fluid and plasm of patients with primary knee medical osteoarthritis after high tibial osteotomy]

Objective

To investigate interleukin-1β (IL-1β), IL-6, and IL-17 levels in both synovial fluid and serum of patients with primary knee medial osteoarthritis (OA) after high tbial osteotomy (HTO).

Methods

Twenty-six patients with primary knee medial OA undergoing HTO between January 2011 and June 2014 (experimental group) and 30 healthy individuals (control group) were recruited into the study. There was no significant difference in gender, age, and body mass index between 2 groups ( P>0.05). The X-ray film was taken to record healing time at osteotomy site, to measure the tibiofemoral angle, and to assess limb alignment after HTO. Visual analogue scale (VAS) pain score and knee society score (KSS) were used to evaluate pain level and function of the knee. The IL-1β, IL-6, and IL-17 concentrations in both plasma and synovial fluid were measured before operation and at 6, 12, and 18 months after operation in the experimental group using ELISA method; the levels in plasma were measured in control group.

Results

Primary healing of incisions was achieved in patients. All patients were followed up 18-24 months (mean, 21 months). The X-ray film showed osseous healing at osteotomy site at 9-14 weeks (mean, 11.5 weeks). The average tibiofemoral angle was 167.5° (range, 165-170°) after bone healing. Satisfactory limb alignment was obtained in all patients. The postoperative VAS pain score was significantly decreased and KSS score was significantly improved when compared with preoperative scores ( P<0.05), but no significant difference was found between different time points after operation ( P>0.05). The preoperative plasma and synovial fluid IL-1β, IL-6, and IL-17 concentrations were significantly higher in patients than controls ( P<0.05). The postoperative IL-1β, IL-6, and IL-17 concentrations in plasma and synovial fluid were significantly lower than preoperative ones in patients ( P<0.05), but the concentrations were significantly higher than those in controls ( P<0.05). The postoperative plasma and synovial fluid IL-1β, IL-6, and IL-17 concentrations were significantly declined in patients, but there was no significant difference between different time points after operation ( P>0.05).

Conclusion

HTO can significantly improve the pain symptom and joint function and reduce IL-1β, IL-6, and IL-17 levels in both plasma and synovial fluid of patients with medial compartment knee OA, but these cytokines can not return to normal level.

Visfatin Promotes IL-6 and TNF-α Production in Human Synovial Fibroblasts by Repressing miR-199a-5p through ERK, p38 and JNK Signaling Pathways

Osteoarthritis (OA), an inflammatory form of arthritis, is characterized by synovial inflammation and cartilage destruction largely influenced by two key proinflammatory cytokines-interleukin-6 (IL-6) and tumor necrosis factor α (TNF-α). Notably, levels of visfatin (a proinflammatory adipokine) are elevated in patients with OA, although the relationship of visfatin to IL-6 and TNF-α expression in OA pathogenesis has been unclear. In this study, visfatin enhanced the expression of IL-6 and TNF-α in human OA synovial fibroblasts (OASFs) in a concentration-dependent manner and stimulation of OASFs with visfatin promoted phosphorylation of extracellular-signal-regulated kinase (ERK), p38, and c-Jun N-terminal kinase (JNK), while ERK, p38, and JNK inhibitors or siRNAs all abolished visfatin-induced increases in IL-6 and TNF-α production. Moreover, transfection with miR-199a-5p mimics reversed visfatin-induced increases in IL-6 and TNF-α production. Furthermore, we also found that visfatin-promoted IL-6 and TNF-α production is mediated via the inhibition of miR-199a-5p expression through the ERK, p38, and JNK signaling pathways. Visfatin may therefore be an appropriate target for drug intervention in OA treatment.

* Extracellular Matrices for Bone Regeneration: A Literature Review

The gold standard material for bone regeneration is still autologous bone, a mesenchymal tissue that consists mainly of extracellular matrix (ECM) (90% v/v) and little cellular content (10% v/v). However, the fact that decellularized allogenic bone grafts often present a clinical performance comparable to autologous bone grafts demonstrates the crucial role of ECM in bone regeneration. For long, the mechanism by which bone allografts function was not clear, but recent research has unveiled many unique characteristics of ECM that seem to play a key role in tissue regeneration. This is further confirmed by the fact that synthetic biomaterials with composition and properties resembling bone ECM present excellent bone regeneration properties. In this context, ECM molecules such as glycosaminoglycans (GAGs) and self-assembly peptides (SAPs) can improve the performance of bone regeneration biomaterials. Moreover, decellularized ECM derived either from native tissues such as bone, cartilage, skin, and tooth germs or from cells such as osteoblasts, chondrocytes, and stem cells has shown promising results in bone regeneration applications. Understanding the role of ECM in bone regeneration is crucial for the development of the next generation of biomaterials for bone tissue engineering. In this sense, this review addresses the state-of-the-art on this subject matter.

Human tooth-derived biomaterial as a graft substitute for hard tissue regeneration

Aim: The present study was conducted to evaluate the efficacy of human dentine grafts for new bone augmentation. Materials & methods: Dentine grafts (demineralized dentine matrix [DDM] and mineralized dentine matrix [MDM]) were prepared and implanted in rats. Tetracycline was administered twice. Paraffin and resin sections were prepared from the harvested grafts and stained respectively with hematoxylin and eosin (in addition to tartrate acid phosphatase for osteoclasts) and Villanueva. The new bone formation (bone thickness, mineral apposition rate and the bone formation rate) was analyzed in tetracycline-labeled resin sections. Results & conclusion: DDM grafts implanted in bone were better able to augment the bone compared to MDM grafts. However, both MDM and DDM failed to induce new bone in ectopic site, they could be considered as alternative autograft substitutes after protocol optimization.

Epigenetic modifications of interleukin-6 in synovial fibroblasts from osteoarthritis patients

Osteoarthritis (OA) is the most common degenerative disease of the synovial joint. The synovial membrane is responsible for the inflammatory reaction leading to the secretion of macrophage-derived pro-inflammatory cytokines, such as IL-6. Suppressing IL-6 over-expression in synovial fibroblasts (SF) is a promising method to prevent OA development and progression, in which the prerequisite is the elucidation of the molecular mechanisms underlying IL-6 over-expression in SF. Currently, there are few reports concerning epigenetic modifications in IL-6 in OA SF. In the present study, we attempted to investigate this phenomenon. SF over-expressing IL-6 was collected from OA patients. DNA hypomethylation and histone hyperacetylation were observed in the IL-6 promoter regions in OA SF compared with normal SF. No differences in the status of H3K9 di-methylation, H3K27 tri-methylation and H3K4 tri-methylation were observed in the IL-6 promoter regions between normal and OA SF. DNA (cytosine-5-)-methyltransferase 3 alpha (Dnmt3a) overexpression and anacardic acid (histone acetyltransferase inhibitor) treatment increased DNA methylation and decreased histone acetylation in the IL-6 promoter, and IL-6 over-expression in OA SF was suppressed. These observations provide deeper insight into the pathogenesis of OA and can be used to design new drugs and develop new therapeutic methods to treat OA.

Metabolic stress-induced joint inflammation and osteoarthritis

Osteoarthritis (OA) is a heterogeneous disorder with several risk factors. Among them, obesity has a major impact on both loading and non-loading joints. Mechanical overload and activity of systemic inflammatory mediators derived from adipose tissue (adipokines, free fatty acids (FFA), reactive oxygen species (ROS)) provide clues to the increased incidence and prevalence of OA in obesity. Recently, research found greater OA prevalence and incidence in obese patients with cardiometabolic disturbances than "healthy" obese patients, which led to the description of a new OA phenotype - metabolic syndrome (MetS)-associated OA. Indeed, individual metabolic factors (diabetes, dyslipidemia, and hypertension) may increase the risk of obesity-induced OA. This review discusses hypotheses based on pathways specific to a metabolic factor in MetS-associated OA, such as the role of advanced glycation end products (AGEs) and glucose toxicity. A better understanding of these phenotypes based on risk factors will be critical for designing trials of this specific subset of OA.

Association of interleukin-6 gene polymorphism (rs1800796) with severity and functional status of osteoarthritis in elderly individuals

Osteoarthritis (OA) is the most prevalent disease of the musculoskeletal system and it has an important genetic component. Despite several reports have shown the involvement of pro-inflammatory cytokine such as interleukin-1β and TNF-α, the role of interleukin-6 (IL-6) in osteoarthritis is still unclear. Thus, this study aimed to analyze the relationship between the single nucleotide polymorphism in the portion -572 of the promoter region of the IL6 gene (SNP -572G/C) with hip and knee OA in the elderly. In this case-control study, 257 physically independent elderly were recruited (case group: 92 individuals with osteoarthritis and control group: 165 individuals with no osteoarthritis). Blood samples were collected from patients for the DNA fragments extraction and amplification by real-time polymerase chain reaction (PCR) by TaqMan system for subsequent genotyping of IL6 gene. The degree of joint damage was assessed by radiographic classification based on the criteria of Kellgren and Lawrence. The functional status was evaluated by Lequesne and WOMAC questionnaires. It was observed that individuals carrying the C allele have lower susceptibility to osteoarthritis (OR=0.51, 95% CI: 0.32-0.80, p=0.004) and less radiological impairment for both hip (Fisher-Freeman-Halton test=4.2 and p=0.04) and knee joints (Fisher-Freeman-Halton test=4.7 and p=0.03). Regarding functional status, individuals carrying the C allele has a lower degree of functional impairment assessed by WOMAC (Mann-Whitney test, p=0.04), although no difference was observed in the Lequesne questionnaire (p>0.05). Additionally, it was observed a marked reduction in IL-6 serum levels in individuals with GC and CC genotypes when compared to individuals harboring GG genotype. In conclusion, the polymorphism -572G/C IL6 is a protective factor for the presence and severity of hip and knee osteoarthritis in the elderly. Further prospective studies with large sample size and methods (e.g. effect of this polymorphism on gene expression, haplotype analysis for IL-6 promoter polymorphism) are needed to validate this study findings.

Genetic polymorphisms of interleukin-16 and risk of knee osteoarthritis

BACKGROUND

Interleukin-16 (IL-16), a pleiotropic cytokine, plays a fundamental role in inflammatory diseases. This study investigates the association between IL-16 polymorphisms and the risk of knee osteoarthritis (OA) in a Chinese population.

METHODS

The IL-16 rs11556218, rs4072111, and rs4778889 polymorphisms were determined in 150 knee OA cases and 147 healthy controls through polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

The results suggested that the variants in IL-16 gene rs11556218 site were associated with a decreased knee OA risk after adjusting for age, sex, BMI, and smoking and drinking status (TG vs. TT: OR, 0.69; 95% CI, 0.53-0.89; P = 0.006; GG vs. TT: OR, 0.64; 95% CI, 0.45-0.90; P = 0.042; dominant model: OR, 0.68; 95% CI, 0.29-0.87; P = 0.002; G vs. T allele: OR, 0.77; 95% CI, 0.66-0.90; P = 0.003). Similarly, subjects bearing the rs4072111 variant genotypes and alleles also had a lower susceptibility to knee OA compared with those bearing the wild-type (CT vs. CC: OR, 0.66; 95% CI, 0.53-0.83; P = 0.002; TT vs. CC: OR, 0.57; 95% CI, 0.40-0.82; P = 0.027; dominant model: OR, 0.65; 95%, CI 0.52-0.80; P <0.001; T vs. C allele: OR, 0.69; 95% CI, 0.58-0.81; P <0.001). Further, the C allele and the combined genotype (CC+CT) of rs4778889 were associated with a slightly decreased risk of knee OA. In addition, we found two high-risk haplotypes: TTT (OR, 3.70) and GCC (OR, 6.22). Finally, serum IL-16 levels of knee OA patients were significantly higher than those of controls (P = 0.001).

CONCLUSIONS

Despite the small sample size, this is the first study suggesting IL-16 gene polymorphisms to be associated with the risk of knee OA.

An insight into rheumatology in Thailand

Despite the fact that rheumatic diseases constitute a common health care problem in Thailand, improvements in rheumatology education, research and health care are still required. Low numbers of rheumatologists, their uneven distribution, lack of time to perform both clinical and basic research, lack of patient compliance and restricted access to effective medication comprise some of the barriers that need to be overcome to establish rheumatology education, research and care with a Western-country benchmark. The annual academic activities provided by the Thai Rheumatism Association for rheumatologists, general practitioners, allied health professionals and patients can advance only some forms of education and health care. Better cooperation between the Thai Rheumatism Association, the Royal College of Physicians of Thailand, the Ministry of Public Health and the Thai government is needed to improve rheumatology training, care and research in the country.

Relationships of common polymorphisms in IL-6, IL-1A, and IL-1B genes with susceptibility to osteoarthritis: a meta-analysis

Observational and experimental studies have arrived at inconsistent conclusions about whether common polymorphisms in IL-6, IL-1A, and IL-1B genes are associated with an increased risk of osteoarthritis (OA). Therefore, we undertook a comprehensive meta-analysis to more systematically summarize the relationships of IL-6, IL-1A, and IL-1B genetic polymorphisms with susceptibility to OA. We screened the PubMed, Embase, Web of Science, Cochrane Library, CISCOM, CINAHL, Google Scholar, China BioMedicine (CBM), and China National Knowledge Infrastructure (CNKI) databases up to 31 March 2014. We used STATA software to analyze statistical data. Odds ratios (ORs) and their corresponding 95 % confidence intervals (95 % CIs) were calculated. Seventeen independent case-control studies were included in this meta-analysis with a total number of 7,491 subjects, comprised of 3,293 OA patients and 4,729 healthy controls. Our results indicate that IL-6, IL-1A, and IL-1B genetic polymorphisms are statistically correlated with an increased risk of OA under the allele and dominant models. According to a subgroup analysis based on disease, a higher frequency of IL-6 genetic polymorphisms was observed among knee OA and hand OA patients, but not among hip OA and DIP OA patients. A higher frequency of IL-1A genetic polymorphisms were found among hip OA patients, hand OA, hip OA and DIP OA patients. Furthermore, we observed a higher IL-1B polymorphism frequency among knee OA and hip OA patients, but not among hand OA patients. Our findings provide evidence that IL-6, IL-1A, and IL-1B genetic polymorphisms may be correlated with susceptibility to OA.

The role of inflammatory and anti-inflammatory cytokines in the pathogenesis of osteoarthritis

Osteoarthritis (OA) is the most common chronic disease of human joints. The basis of pathologic changes involves all the tissues forming the joint; already, at an early stage, it has the nature of inflammation with varying degrees of severity. An analysis of the complex relationships indicates that the processes taking place inside the joint are not merely a set that (seemingly) only includes catabolic effects. Apart from them, anti-inflammatory anabolic processes also occur continually. These phenomena are driven by various mediators, of which the key role is attributed to the interactions within the cytokine network. The most important group controlling the disease seems to be inflammatory cytokines, including IL-1β, TNFα, IL-6, IL-15, IL-17, and IL-18. The second group with antagonistic effect is formed by cytokines known as anti-inflammatory cytokines such as IL-4, IL-10, and IL-13. The role of inflammatory and anti-inflammatory cytokines in the pathogenesis of OA with respect to inter- and intracellular signaling pathways is still under investigation. This paper summarizes the current state of knowledge. The cytokine network in OA is put in the context of cells involved in this degenerative joint disease. The possibilities for further implementation of new therapeutic strategies in OA are also pointed.

Association of IL-6 G-174C polymorphism with bone mineral density

Functional polymorphisms in the promoter region of interleukin-6 (IL-6) are known to be involved in bone mineral density (BMD) and the development of osteoporosis, but the reported results have been inconsistent. Using the meta-analysis approach, the present study is designed to provide a relatively comprehensive picture of the relationship between bone mineral density (BMD) or osteoporosis and polymorphisms in the promoter region of IL-6 (rs1800795 and rs1800796). The difference of bone mineral density (BMD) values between genotypes was examined by mean difference and 95 % confidence intervals (CIs). Association between IL-6 polymorphism and clinical osteoporosis was evaluated by pooled odds ratios (ORs) and 95 % CIs. A total of 13 articles with 11,499 subjects were included in the present study. For -174 (rs1800795), we found that individuals with the G/G genotype had a significantly lower BMD value than those with C/C genotype at femoral neck (0.02 g/cm(2), 95 % CI 0.00-0.03) (p = 0.04) and distal radius (0.01 g/cm(2), 95 %CI 0.01-0.01) (p < 0.0001). However, we did not find a statistically significant difference of BMD at the spine. When analysis was limited to postmenopausal women, similar results were obtained. We further found that the C/C genotype was associated with a reduced risk of osteoporosis compared to G/G genotype, and the pooled OR was 0.72 (95 % CI 0.54-0.95, p = 0.02). In addition, a significant relationship was found between G-634C (rs1800796) polymorphism and distal radius BMD (CC vs. GG: 0.02 g/cm(2), 95 % CI 0.01-0.03; GC vs. GG: 0.02 g/cm(2), 95 % CI 0.00-0.03) in the Asian population. These findings suggest that the CC genotype of IL-6 G-174C polymorphism may be associated with high BMD at femoral neck and distal radius and decreased risk of osteoporosis in the Caucasian population whereas G-634C polymorphism was associated with distal radius BMD in Asians.

Association of adiponectin +276G/T polymorphism with knee osteoarthritis

Osteoarthritis (OA) is a prevalent, degenerative joint disorder leading to the destruction of articular cartilage, osteophyte formation and subchondral bone sclerosis. Genetic and environmental factors are involved in the development of OA. The role of adiponectin gene polymorphisms in OA has not yet been established. The aim of this study was to investigate the association of adiponectin +276G/T (rs1501299) gene polymorphism with knee OA. Genotype distributions and allelic frequencies of adiponectin gene, +276G/T polymorphism were determined in a total of 200 subjects (100 knee OA patients and 100 healthy controls). Single-nucleotide polymorphism (SNP) of the adiponectin +276G/T gene was genotyped by polymerase chain reaction (PCR)-restriction fragment length polymorphism analysis. The genotype distribution of +276G/T SNP was observed in the Hardy-Weinberg equilibrium for OA patients and controls. No statistically significant difference was identified between the two groups with respect to genotype distributions and allelic frequencies (P>0.05). The T- and G-allele frequencies were indicated as 24.5 and 75.5%, respectively, in OA patients, whereas the frequency was 23-70% in the control group. Findings of this study therefore suggest that the +276G/T SNP was not associated with susceptibility to knee OA.

Association of IL-17A and IL-17F single nucleotide polymorphisms with susceptibility to osteoarthritis in a Korean population

The damage incurred in osteoarthritis (OA) is mediated by a variety of cytokines, growth factors and inflammatory mediators. The importance of the interleukin-17 (IL-17) family in inflammatory and autoimmune disease is becoming increasingly apparent. Microsatellite association mapping reveals a primary osteoarthritis susceptibility locus on chromosome 6p12.3-q13. IL-17A and IL-17F genes that resided on chromosome 6p12.3-q13 are believed to play an important role in the primary OA susceptibility. We investigated the allele and genotype of IL-17A G-197A and IL-17F T7488C in 302 OA patients and 300 healthy subjects as controls. We employed a PCR-SSCP assay to identify the genotypes IL-17A G-197A and IL-17F T7488C. For IL-17A G-197A, there were significant differences in frequencies of genotype and allele of IL-17A G-197A between OA patients and controls (both p<0.0001). For IL-17F T7488C, there were no significant differences in the allele frequency and genotype distribution for IL-17F T7488C between OA patients and controls (p=0.938 and p=0.1735, respectively). In conclusion, current study showed that polymorphism of IL-17A G-197A may be closely associated with susceptibility to the development of OA in the Korean population. However, there was no relationship between IL-17F T7488C polymorphism and OA susceptibility.

Hybrid grafting of post-traumatic bone defects using β-tricalcium phosphate and demineralized bone matrix

OBJECTIVES

Management of post-traumatic bone defects continues to be a substantial clinical challenge in orthopaedic trauma. This retrospective study evaluates the results of primary hybrid grafting of residual bone defects or voids, in displaced and comminuted long-bone fractures treated by plate fixation, using β-tricalcium phosphate and demineralized bone matrix.

MATERIALS AND METHODS

Fifty-four patients having 62 fractures were included. Their mean age was 40.7±10.7 years; femoral and tibial fractures were the commonest (70.9%) in this study. Eight fractures (12.9%) were open injuries; 13 fractures had critical-sized defects that averaged 3.4±0.9 cm. Cortical bone defects occurred in 51 cases, and cancellous bone voids in eleven. Eleven patients (20%) were polytraumatized. Tobramycin powder was added to the graft in all open fractures. The functional outcome was evaluated according to a modified Karlström and Olerud criteria.

RESULTS

All fractures (100%) had solid union without any implant failure. There was a significant delayed union (P<0.001) in all critical-sized defects. The mean healing time showed a highly significant difference (P<0.001) between closed and open fractures. The functional outcome was excellent in 28 fractures, good in 21 fractures, fair in nine fractures and poor in four fractures.

CONCLUSIONS

We believe that the ideal bone graft substitute for all situations does not exist; however, this hybrid grafting is a very good alternative to autogenous grafts especially in polytraumatized patients and when massive bone grafting is needed to reconstruct more than one bone in absence of segmental defects.

CCN4 induces IL-6 production through αvβ5 receptor, PI3K, Akt, and NF-κB singling pathway in human synovial fibroblasts

Introduction

Osteoarthritis (OA) is the most common degenerative joint disease that is involved in the degradation of articular cartilage. The exact etiology of OA is not completely understood. CCN4 is related to up-regulation in the cartilage of patients with osteoarthritis. Previous studies have shown that CCN4 might be associated with the pathogenesis of OA, but the exact signaling pathways in CCN4-mediated IL-6 expression in synovial fibroblasts (SF) are largely unknown. Therefore, we explored the intracellular signaling pathway involved in CCN4-induced IL-6 production in human synovial fibroblast cells.

Methods

CCN4-induced IL-6 production was assessed with quantitative real-time qPCR and ELISA. The mechanisms of action of CCN4 in different signaling pathways were studied by using Western blotting. Neutralizing antibodies of integrin were used to block the integrin signaling pathway. Luciferase assays were used to study IL-6 and NF-κB promoter activity. Immunocytochemistry was used to examine the translocation activity of p65.

Results

Osteoarthritis synovial fibroblasts (OASFs) showed significant expression of CCN4 and the expression was higher than in normal SFs. OASF stimulation with CCN4 induced concentration- and time-dependent increases in IL-6 production. Pretreatment of OASFs with αvβ5 but not α5β1 and αvβ3 integrin antibodies reduced CCN4-induced IL-6 production. CCN4-mediated IL-6 production was attenuated by PI3K inhibitor (LY294002 and Wortmannin), Akt inhibitor (Akti), and NF-κB inhibitor (PDTC and TPCK). Stimulation of cells with CCN4 also increased PI3K, Akt, and NF-κB activation.

Conclusions

Our results suggest that CCN4 activates αvβ5 integrin, PI3K, Akt, and NF-κB pathways, leading to up-regulation of IL-6 production. According to our results, CCN4 may be an appropriate target for drug intervention in OA in the future.

The interaction between obesity and RAGE polymorphisms on the risk of knee osteoarthritis in Chinese population

BACKGROUND

The receptor for advanced glycation end products (RAGE) has been reported to relate to osteoarthritis (OA), however, the role of RAGE genetic variants in OA remains unknown.

METHOD

A total of 233 patients with primary knee OA and 255 healthy volunteer were recruited. Three RAGE gene polymorphisms, namely, Gly82Ser (rs2070600). -374T/A (rs1800624) and 429T/C (rs1800625) were genotyped.

RESULTS

Of all three RAGE gene polymorphisms, only the genotype distributions and alleles frequencies of 82G/S polymorphisms significantly differed between knee OA and control subjects. The presence of SS genotype and S allele of 82G/S we significantly higher in knee OA subjects than in controls (34.76% vs. 19.61%, P for trend =0.004; 57.64% vs. 48.59%, P for trend <0.001, respectively). Multivariate logistic regression analysis showed a significantly increased risk for knee OA for the SS genotype compared with the AA genotype (OR= 1.984, 95% CI: 1.238-3.181; P =0.004). The adjusted OR for S allele carriage was significantly higher than G allele carriage (OR=1.440, 95% CI: 1.137-1.8231, P=0.002). Moreover, a significant multiplicative interaction was observed between 82G/S polymorphisms with obesity (Pinteraction=0.028). Taking the non-obese 82GG genotype as references, the OR for OA in non-obese SS carriers was 2.537 (95% CI 1.241-5.189, P=0.001). Notably, the OR in obese GS carriers was 2.304 (95% CI: 1.218-4.357, P=0.009) and in obese SS was 3.392 (95% CI: 1.672-6.885, P=0.001). The -374T/A and -429T/C did not show positive interaction with obesity and smoking status.

CONCLUSION

The AGE 82G/S polymorphisms, in interaction with obesity, may determine the susceptibility of OA in Chinese population.