Nickel ions bind to HSP90β and enhance HIF-1α-mediated IL-8 expression

Caspases downregulate nickel and hydrogen peroxide-induced IL-8 production via modification of c-Jun N-terminal kinases

Nickel (Ni) is a typical hapten in allergic contact dermatitis. However, it has been used in various metal materials due to its usefulness. Although Ni ions induce apoptosis of inflammatory cells and the expression of inflammatory cytokines such as interleukin-8 (IL-8), the effects of the apoptotic pathway on the signaling that induces cytokine production have not been sufficiently clarified. Here, we found that NiCl2-induced IL-8 production was enhanced by the pan-caspase inhibitor Z-VAD-FMK in THP-1 cells. Moreover, Z-VAD-FMK enhanced H2O2-induced and NiCl2-induced IL-8 production, but not TNF-α-induced one. The analyses of signaling pathways apparently showed that NiCl2- and H2O2-induced phosphorylation of c-Jun, but not TNF-α-induced one were enhanced by Z-VAD-FMK. The cleavages of p54c-Jun N-terminal kinase (JNK) as well as PARP was induced by NiCl2 and H2O2 but not by TNF-α. Finally, a JNK inhibitor, SP600125, inhibited Z-VAD-FMK-induced enhancement of IL-8 production. In summary, we showed that caspase activation in the apoptotic pathway actively downregulates the JNK-mediated activation of inflammatory cells. This study highlighted the significance of apoptosis in inflammatory diseases, including Ni-induced dermatitis.

Differential expression and localization of immunity-related factors in main immune organs of yak

The yak is an agricultural animal with strong disease resistance in Qinghai-Tibet Plateau. Immune organs are directly involved in the body's immune response and protect it from external aggression. In this study, we characterized and evaluated the main markers of interleukin (IL)-1β, IL-17a, hypoxia inducer factor-1 (HIF-1)α, and heat shock protein 90 (HSP90) in the lymph nodes, spleen, thymus, and hemal nodes of adult yaks using network informatics, molecular cloning, immunohistochemistry, real-time quantitative polymerase chain reaction (RT-qPCR), and western blotting. We first cloned the IL-1β and IL-17a mRNA of yaks. A significant feature was the higher IL-1β and IL-17a expression in the lymph nodes than in the spleen, hemal nodes, and thymus. Immunohistochemistry and immunofluorescence revealed that IL-1β and IL-17a cells were mainly located in the paracortex area of the lymph nodes and the T-cell-dependent area in the hemal nodes and spleen. Several HIF-1α proteins were detected in the cortex of the hemal nodes mantle, while HSP90 was detected in the lymphoid nodules of the hemal nodes and lymph nodes. This study sheds light on the relationship between the morphology and function of these organs and provides an important reference for studies on the participation of yak immune organs in immune responses.

Association Between Heavy Metals Exposure and Height in Chinese Preschoolers

OBJECTIVES

This study aimed to explore the association between multiple metals' exposure and children's height.

METHODS

We collected urine samples and physical measurement data of 1477 preschoolers in China. Children's actual height was measured, and whether reached target height was also assessed. Logistic regression analysis was performed to explore the association between heavy metals and height. The least absolute shrinkage and selection operator regression was used to select the urinary metals, which were highly correlated.

RESULTS

In the single-metal model after adjusting for potential confounders, urinary iron, aluminum, nickel, chrome, titanium, vanadium, selenium, rubidium, and thallium levels were negatively associated with actual height. Urinary iron, aluminum, nickel, and chrome concentrations were also negatively associated with target height.

CONCLUSIONS

The findings suggested that some urinary metal exposure might be associated with height in preschoolers.

The role of hypoxia-inducible factor 1 alpha (HIF-1α) modulation in heavy metal toxicity

Hypoxia-inducible factor 1 (HIF-1) is an oxygen-sensing transcriptional regulator orchestrating a complex of adaptive cellular responses to hypoxia. Several studies have demonstrated that toxic metal exposure may also modulate HIF-1α signal transduction pathway, although the existing data are scarce. Therefore, the present review aims to summarize the existing data on the effects of toxic metals on HIF-1 signaling and the potential underlying mechanisms with a special focus on prooxidant effect of the metals. The particular effect of metals was shown to be dependent on cell type, varying from down- to up-regulation of HIF-1 pathway. Inhibition of HIF-1 signaling may contribute to impaired hypoxic tolerance and adaptation, thus promoting hypoxic damage in the cells. In contrast, its metal-induced activation may result in increased tolerance to hypoxia through increased angiogenesis, thus promoting tumor growth and contributing to carcinogenic effect of heavy metals. Up-regulation of HIF-1 signaling is mainly observed upon Cr, As, and Ni exposure, whereas Cd and Hg may both stimulate and inhibit HIF-1 pathway. The mechanisms underlying the influence of toxic metal exposure on HIF-1 signaling involve modulation of prolyl hydroxylases (PHD2) activity, as well as interference with other tightly related pathways including Nrf2, PI3K/Akt, NF-κB, and MAPK signaling. These effects are at least partially mediated by metal-induced ROS generation. Hypothetically, maintenance of adequate HIF-1 signaling upon toxic metal exposure through direct (PHD2 modulation) or indirect (antioxidant) mechanisms may provide an additional strategy for prevention of adverse effects of metal toxicity.

Quercetin improves pancreatic cancer chemo-sensitivity by regulating oxidative-inflammatory networks

Chemotherapy is the main method for controlling pancreatic cancer metastasis but the prevalent chemotherapy resistance limits its utilization. The response of oxidation and inflammation often promotes pancreatic cancer progression and chemo-resistance. It is critical to explore the potential natural products with few side effects to control inflammatory responses and understand the related mechanisms. Quercetin is a flavonoid widely found in numerous vegetables, fruits, and foods and is thought to have antioxidant and anti-inflammatory properties, which may be associated with improvement of chemotherapy sensitivity during pancreatic cancer treatment. Quercetin may sensitize pancreatic cancer cells to the chemotherapeutic agents, including bromodomain and extraterminal domain inhibitors (BETI), daunorubicin, gemcitabine, sulforaphane, doxorubicin, and tumor necrosis factor-related signaling apoptosis-inducing ligand (TRAIL). Meanwhile, during the chemo-resistance therapy, many signaling molecules are involved with toll-like receptor 4 (TLR4)-mediated oxidative and inflammatory pathway. The effects of quercetin on other oxidative and inflammatory pathways were also explored. Quercetin may exert antitumor activity during the prevention of pancreatic cancer progression by regulating oxidative and inflammatory networks, which can promote immune escape of cancer cells by inducing immunosuppressive cytokines. Studying these patterns will help us to better understand the functional role of quercetin in the improvement of pancreatic cancer chemo-sensitivity. PRACTICAL APPLICATIONS: Chemotherapy is the major way for treating pancreatic cancer metastasis but the prevalent chemotherapy resistance caused by oxidative and inflammatory responses limits its utilization. It is necessary to explore the potential natural products with few side effects to prevent the oxidative and inflammatory responses. Quercetin is a flavonoid widely found in numerous vegetables, fruits, and foods and is thought to have antioxidant and anti-inflammatory properties, which may be associated with improvement of chemotherapy sensitivity of pancreatic cancer treatment by sensitizing pancreatic cancer cells to various chemotherapeutic agents via the regulation of oxidative and inflammatory networks. Studying these patterns will help us to better understand the functional role of quercetin in the improvement of pancreatic cancer chemo-sensitivity.

Cytosolic Hsp90 Isoform-Specific Functions and Clinical Significance

The heat shock protein 90 (Hsp90) is a molecular chaperone and a key regulator of proteostasis under both physiological and stress conditions. In mammals, there are two cytosolic Hsp90 isoforms: Hsp90α and Hsp90β. These two isoforms are 85% identical and encoded by two different genes. Hsp90β is constitutively expressed and essential for early mouse development, while Hsp90α is stress-inducible and not necessary for survivability. These two isoforms are known to have largely overlapping functions and to interact with a large fraction of the proteome. To what extent there are isoform-specific functions at the protein level has only relatively recently begun to emerge. There are studies indicating that one isoform is more involved in the functionality of a specific tissue or cell type. Moreover, in many diseases, functionally altered cells appear to be more dependent on one particular isoform. This leaves space for designing therapeutic strategies in an isoform-specific way, which may overcome the unfavorable outcome of pan-Hsp90 inhibition encountered in previous clinical trials. For this to succeed, isoform-specific functions must be understood in more detail. In this review, we summarize the available information on isoform-specific functions of mammalian Hsp90 and connect it to possible clinical applications.

Effects of arsenic and heavy metals on metabolic pathways in cells of human origin: Similarities and differences

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There are distinctive overlaps in different heavy metal affected metabolic pathways.

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Affected pathways vary according to the tissue origin and maturity of the cell.

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Arsenic appears to have relatively more pleiotropic effects on metabolic pathways.

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Some of the arsenic affected pathways are associated with diabetes.

Various anthropogenic and natural events over the years have gradually increased human exposure to various heavy metals. Several of these heavy metals including cadmium, mercury, nickel, chromium, and the metalloid arsenic among others, have created major public health concerns for their high level of toxicities. Identification of the general as well as the differentially affected cellular metabolic pathways will help understanding the molecular mechanism of different heavy metal-induced toxicities. In this study, we analyzed 25 paired (control vs. treated) transcriptomic datasets derived following treatment of various human cells with different heavy metals and metalloid (arsenic, cadmium, chromium, iron, mercury, nickel and vanadium) to identify the affected metabolic pathways. The effects of these metals on metabolic pathways depend not only on the metals per se, but also on the nature of the treated cells. Tissue of origin, therefore, must be considered while assessing the effects of any particular heavy metal or metalloid. Among the metals and metalloid, arsenic appears to have relatively more pleiotropic influences on cellular metabolic pathways including those known to have association with diabetes. Although only two stem cell derived datasets are included in the current study, effects of heavy metals on these cells appear to be different from other mature cells of similar tissue origin. This study provides useful information about different heavy metal affected pathways, which may be useful in further exploration using wet-lab based techniques.

The Contact Allergen NiSO4 Triggers a Distinct Molecular Response in Primary Human Dendritic Cells Compared to Bacterial LPS

Dendritic cells (DC) play a central role in the pathogenesis of allergic contact dermatitis (ACD), the most prevalent form of immunotoxicity in humans. However, knowledge on allergy-induced DC maturation is still limited and proteomic studies, allowing to unravel molecular effects of allergens, remain scarce. Therefore, we conducted a global proteomic analysis of human monocyte-derived dendritic cells (MoDC) treated with NiSO4, the most prominent cause of ACD and compared proteomic alterations induced by NiSO4 to the bacterial trigger lipopolysaccharide (LPS). Both substances possess a similar toll-like receptor (TLR) 4 binding capacity, allowing to identify allergy-specific effects compared to bacterial activation. MoDCs treated for 24 h with 2.5 μg/ml LPS displayed a robust immunological response, characterized by upregulation of DC activation markers, secretion of pro-inflammatory cytokines and stimulation of T cell proliferation. Similar immunological reactions were observed after treatment with 400 μM NiSO4 but less pronounced. Both substances triggered TLR4 and triggering receptor expressed on myeloid cells (TREM) 1 signaling. However, NiSO4 also activated hypoxic and apoptotic pathways, which might have overshadowed initial signaling. Moreover, our proteomic data support the importance of nuclear factor erythroid 2-related factor 2 (Nrf2) as a key player in sensitization since many Nrf2 targets genes were strongly upregulated on protein and gene level selectively after treatment with NiSO4. Strikingly, NiSO4 stimulation induced cellular cholesterol depletion which was counteracted by the induction of genes and proteins relevant for cholesterol biosynthesis. Our proteomic study allowed for the first time to better characterize some of the fundamental differences between NiSO4 and LPS-triggered activation of MoDCs, providing an essential contribution to the molecular understanding of contact allergy.

Lactate released from human fibroblasts enhances Ni elution from Ni plate

Elution of Ni ions from medical devices induces inflammation and toxicity. We previously reported that elution of Ni ions from Ni wires induced COX-2 expression and increased lactate production, but whether lactate is involved in the further elution of Ni ions remains unclear. In this study, using KMST-6, a human fibroblast cell line, we examined the molecular mechanisms by which Ni ions increase lactate release and the role of lactate in enhancing the elution of Ni ions. When KMST-6 cells were incubated on a Ni plate or stimulated with NiCl₂ (1 mM), the expression of glucose transporter 1 (GLUT1), hexokinase 2 (HK2), and lactate dehydrogenase A (LDHA), and the release of lactate were enhanced. The NiCl₂ (1 mM)-induced expression of these genes was inhibited by a hypoxia-inducible factor-1α (HIF-1α) inhibitor, PX-478 (10-25 μM). Stimulation of cells with a prolyl hydroxylase domain (PHD) inhibitor, roxadustat, increased the expression of these genes, lactate release, and elution of Ni ions at 10 μM. A monocarboxylate transporter-4 (MCT4) inhibitor, syrosingopine, inhibited lactate release from roxadustat-treated cells and reduced the elution of Ni ions by the cells at 10 μM. Finally, syrosingopine (10 μM) reduced the elution of Ni ions by the cells from the Ni plate. These results suggest that elution of Ni ions from metals promotes the production of lactate via HIF-1α-mediated gene expression and causes further Ni elution. Thus, Ni ions show a positive feedback mechanism of Ni elution, and this step may be potentially targeted to protect against metal elution from metal devices.

Serum nickel is associated with craniosynostosis risk: Evidence from humans and mice

BACKGROUND

To date, few studies have explored the effects of exposure to metal mixtures on adverse developmental outcomes, and no reported studies have linked metal exposure to craniosynostosis (CS). The purpose of this study is to investigate the association between metal exposure and the risk of CS by conducting epidemiological and experimental studies.

METHODS

Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the concentrations of 6 metals (chromium [Cr], nickel [Ni], tin [Sn], arsenic [As], thallium [Tl], and lead [Pb]) in serum samples from 174 CS patients and 85 control individuals. Non-syndromic patients with isolated sagittal suture closure were selected as the case group, and healthy children matched by sex and age were selected as controls. Bayesian kernel machine regression (BKMR) models were used to account for joint metal effects. Multiple logistic regression analysis was used to explore the association between metal concentration and CS occurrence, with adjustment for potential confounders. During pregnancy, mice were exposed to Ni (0, 0.05, or 0.1 g/kg/day) until weaning, and the widths of the sutures and shapes of the skull were analysed by micro-CT 3D imaging and histological analysis. MC3T3-E1 cells were treated with Ni (0, 0.005, or 0.05 μg/mL) for 72 h. Alkaline phosphate (ALP) staining and Alizarin red staining were performed to observe the development of osteoblasts. The expression levels of osteoblast-related genes were also detected.

RESULTS

A positive association between the metal mixture and CS risk was observed based on population data; the Ni group had the highest conditional posterior inclusion probability (PIP), at 0.8416, and in the fully adjusted model, the highest Ni exposure level had a more significant association with CS (coefficient = 2.65, 95% CI: 0.29, 5.02) than the lowest Ni exposure level. The mean widths of the sagittal sutures in mice were 8.8 ± 0.6 mm in the control group, 8.0 ± 0.8 mm in the 0.05 g/kg/day group and 6.8 ± 0.4 mm in the 0.1 g/kg/day group. After Ni exposure, ALP gene expression in skull tissue was increased, and ALP activity was increased in MC3T3-E1 cells. Moreover, increased collagen content in mouse skull sections and elevated osteocalcin (OCN) expression in MC3T3-E1 cells were observed in the Ni-treated groups compared to the control group.

CONCLUSIONS

This study is the first to provide evidence that increased serum Ni was associated with an increased risk of CS. Early life exposure to Ni promoted osteogenesis during skull growth, which may contribute to the development of CS.

Update of the risk assessment of nickel in food and drinking water

The European Commission asked EFSA to update its previous Opinion on nickel in food and drinking water, taking into account new occurrence data, the updated benchmark dose (BMD) Guidance and newly available scientific information. More than 47,000 analytical results on the occurrence of nickel were used for calculating chronic and acute dietary exposure. An increased incidence of post-implantation loss in rats was identified as the critical effect for the risk characterisation of chronic oral exposure and a BMDL 10 of 1.3 mg Ni/kg body weight (bw) per day was selected as the reference point for the establishment of a tolerable daily intake (TDI) of 13 μg/kg bw. Eczematous flare-up reactions in the skin elicited in nickel-sensitised humans, a condition known as systemic contact dermatitis, was identified as the critical effect for the risk characterisation of acute oral exposure. A BMDL could not be derived, and therefore, the lowest-observed-adverse-effect-level of 4.3 μg Ni/kg bw was selected as the reference point. The margin of exposure (MOE) approach was applied and an MOE of 30 or higher was considered as being indicative of a low health concern. The mean lower bound (LB)/upper bound (UB) chronic dietary exposure was below or at the level of the TDI. The 95th percentile LB/UB chronic dietary exposure was below the TDI in adolescents and in all adult age groups, but generally exceeded the TDI in toddlers and in other children, as well as in infants in some surveys. This may raise a health concern in these young age groups. The MOE values for the mean UB acute dietary exposure and for the 95th percentile UB raises a health concern for nickel-sensitised individuals. The MOE values for an acute scenario regarding consumption of a glass of water on an empty stomach do not raise a health concern.

Iron overload regulate the cytokine of mesenchymal stromal cells through ROS/HIF-1α pathway in Myelodysplastic syndromes

Iron overload is a significant feature of myelodysplastic syndromes (MDS) patients due to ineffective hematopoiesis and transfusion dependence. Excess iron results in organ dysfunction through the generation of reactive oxygen species (ROS) which can cause oxidative stress even mutation. Mesenchymal stromal cells (MSCs) are responsible for supporting and regulating hematopoiesis, whether MSCs is involved in the pathogenesis of MDS still need further elucidation. Hypoxia-inducible factors-1 (HIF-1) is an integral signal of inflammation that has been shown to up-regulating in MDS patient. We found that MDS-derived MSC had disorganized clones and increased level of apoptosis (n = 53). Iron transportation-related gene, such as DMT1 and ZIP14, and ROS level were increased in iron overload-MDS-MSC (n = 23). HIF-1a, as a crucial part of HIF-1, was also elevated in iron overload-group and PHD2 involved in the degradation of HIF-1a was reduced. Furthermore, HIF-1 downstream cytokines such IL-6, IL-8, TGF-βand VEGF that were also involved in the pathogenesis of MDS were increased in IO-MDS-MSC. When treated with DFO and NAC for iron chelation and antioxidation, the level of HIF-1a and related cytokines could decrease. We conclude that iron overload regulates the cytokine of mesenchymal stromal cells through ROS/HIF-1α pathway in Myelodysplastic syndromes, result in dysfunction of MSC and damage of microenvironment that may be involved in the pathogenesis of MDS.

Interleukin-1 and histamine are essential for inducing nickel allergy in mice

BACKGROUND

We previously reported that (a) lipopolysaccharide (LPS) is a potent adjuvant for inducing Nickel (Ni) allergy in mice at both the sensitization and elicitation steps, (b) LPS induces Interleukin-1 (IL-1) and histidine decarboxylase (HDC, the histamine-forming enzyme), and IL-1 induces HDC, (c) Ni allergy is induced in mast cell-deficient, but not IL-1-deficient (IL-1-KO) or HDC-KO mice.

OBJECTIVE

To examine the roles of IL-1 and HDC (or histamine) and their interrelationship during the establishment of Ni allergy.

METHODS

Ni (NiCl₂ ) 1 mmol/L containing IL-1β and/or histamine was injected intraperitoneally (sensitization step). Ten days later, test substance(s) were intradermally injected into ear pinnas (elicitation step), and ear swelling was measured.

RESULTS

In wild-type mice, Ni + LPS or Ni + IL-1β injection at sensitization step followed by Ni alone at elicitation step induced Ni allergy. In IL-1-KO, injection of Ni + IL-1β (but not Ni + histamine) was required at both sensitization and elicitation steps to induce Ni allergy. In HDC-KO, Ni + IL-1β + histamine at sensitization step followed by Ni + histamine at elicitation step induced Ni allergy. In histamine H1 receptor-deficient mice, IL-1β induced HDC, but was ineffective as an adjuvant for inducing Ni allergy. In wild-type mice, injection into ear pinnas of Ni 10 mmol/L alone or Ni 1 mmol/L + LPS induced IL-1β, HDC and a prolonged swelling of ear pinnas. In non-sensitized mice, injection of IL-1β by itself into ear pinnas in IL-1-KO mice induced prolonged ear swelling. Ni augmented IL-1 production (both IL-1α and IL-1β) and HDC induction in wild-type mice sensitized to Ni.

CONCLUSIONS

In mice: (a) for inducing Ni allergy, IL-1 is essential at both the sensitization and elicitation steps, and HDC induction is involved in the effect of IL-1, (b) stimulation of H1 receptor is also essential for inducing Ni allergy at both sensitization and elicitation steps, and (c) the 'sensitization to Ni' state may be a state where tissues are primed for augmented production of IL-1α and/or IL-1β in response to Ni. (within 300 words, now 300).

Nickel-refining dust regulates the expression of inflammatory factors in NIH/3T3 cells

Nickel (Ni) is a metal known to be a human carcinogen that occupational workers can be exposed to during the process of Ni refining. We investigated the molecular mechanism of inflammation that is induced by Ni-refining dust in a factory, using concentrations of 0, 25, 50, and 100 µg/mL for 24 h and 48 h, in vitro. Quantitative real-time polymerase chain reactions (qRT-PCR), Western blot analysis, and enzyme-linked immunosorbent assays (ELISA) were used to detect the transcriptional expression levels of nuclear factor-κB (NF-κB), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2). Results showed that Ni-refining dust decreased the secretion of IL-6 under the experimental conditions. In contrast, Ni-refining dust activated NF-κB expression and stimulated the secretion of TNF-α, IL-1β, iNOS, and COX-2 in a dose- and time-dependent manner. To summarize, we demonstrated that exposure to Ni-refining dust can induce the expression of NF-κB in NIH/3T3 cells and the secretion of inflammation related factors. This provides a new basis for further study of the inflammatory effects of Ni-refining dust.

Expression of Histidine Decarboxylase and Its Roles in Inflammation

Histamine is a well-known mediator of inflammation that is released from mast cells and basophils. To date, many studies using histamine receptor antagonists have shown that histamine acts through four types of receptors: H1, H2, H3, and H4. Thus, histamine plays more roles in various diseases than had been predicted. However, our knowledge about histamine-producing cells and the molecular mechanisms underlying histamine production at inflammatory sites is still incomplete. The histamine producing enzyme, histidine decarboxylase (HDC), is commonly induced at inflammatory sites during the late and chronic phases of both allergic and non-allergic inflammation. Thus, histamine levels in tissues are maintained at effective concentrations for hours, enabling the regulation of various functions through the production of cytokines/chemokines/growth factors. Understanding the regulation of histamine production will allow the development of a new strategy of using histamine antagonists to treat inflammatory diseases.

Hypoxia regulates angeogenic-osteogenic coupling process via up-regulating IL-6 and IL-8 in human osteoblastic cells through hypoxia-inducible factor-1α pathway

Inappropriate angiogenesis and osteogenesis are considered as the crucial factors of osteoporotic fracture. Hypoxia is a primary driving force for regulating the angiogenic-osteogenic coupling process. Our recent results indicated that hypoxia could improve angiogenesis as well as differentiation and activity of osteoblastic cells via up-regulating VEGF through HIF-1α pathway. Here we demonstrated that in human osteoblastic MG-63, U2-OS and Saos-2 cells, besides VEGF, the other two pro-angiogenic factors IL-6 and IL-8 were also up-regulated by hypoxia and CoCl₂ (a mimic of hypoxia). Mechanism studies indicated overexpression of HIF-1α (generated from transfection with a plasmid encoding sense HIF-1α) markedly increased the levels of IL-6 and IL-8 in osteoblastic cells. Furthermore, a luciferase reporter assay was performed using the reporter vector containing the IL-6 or IL-8 promoter sequence to illustrate observably increased activity of hypoxia-induced IL-6 and IL-8 promoter caused by overexpression of HIF-1α. Additionally, chromatin immune-precipitation analysis showed hypoxia increased the DNA binding ability of HIF-1α to IL-6 or IL-8 promoter. Analysis in vitro by MTT test and Boyden chamber assay showed exogenous IL-6 and IL-8 (a relatively short period of treatment with recombinant IL-6 or IL-8 equivalent to the autocrine levels) could significantly promote the proliferation of human osteoblastic, endothelial and monocytic cells, as well as the migration of human endothelial cells. Taken together, these results indicate that IL-6 and IL-8 in osteoblastic cells may also contribute to the angiogenic-osteogenic coupling process via HIF-1α pathway. Besides VEGF, IL-6- or IL-8-targeted adjunctive therapy maybe a new strategy to improve the treatment of osteoporosis.