The effect of interleukin-1alpha polymorphisms on bone mineral density and the risk of vertebral fractures

Comorbidity of osteoporosis and Alzheimer's disease: Is `AKT `-ing on cellular glucose uptake the missing link?

Osteoporosis and Alzheimer's disease (AD) are both degenerative diseases. Osteoporosis often proceeds cognitive deficits, and multiple studies have revealed common triggers that lead to energy deficits in brain and bone. Risk factors for osteoporosis and AD, such as obesity, type 2 diabetes, aging, chemotherapy, vitamin deficiency, alcohol abuse, and apolipoprotein Eε4 and/or Il-6 gene variants, reduce cellular glucose uptake, and protective factors, such as estrogen, insulin, exercise, mammalian target of rapamycin inhibitors, hydrogen sulfide, and most phytochemicals, increase uptake. Glucose uptake is a fine-tuned process that depends on an abundance of glucose transporters (Gluts) on the cell surface. Gluts are stored in vesicles under the plasma membrane, and protective factors cause these vesicles to fuse with the membrane, resulting in presentation of Gluts on the cell surface. This translocation depends mainly on AKT kinase signaling and can be affected by a range of factors. Reduced AKT kinase signaling results in intracellular glucose deprivation, which causes endoplasmic reticulum stress and iron depletion, leading to activation of HIF-1α, the transcription factor necessary for higher Glut expression. The link between diseases and aging is a topic of growing interest. Here, we show that diseases that affect the same biochemical pathways tend to co-occur, which may explain why osteoporosis and/or diabetes are often associated with AD.

Olive oil exhibits osteoprotection in ovariectomized rats without estrogenic effects

The present study was designed to evaluate the effect of olive oil on bone and uterus in ovariectomized rats. A total of 34 surgically ovariectomized or sham-operated virgin Sprague-Dawley rats were divided into four groups: i) Sham-operated control rats (sham group); ii) Ovariectomized rats (OVX group); iii) Olive oil-supplemented ovariectomized rats (olive group); and iv) Diethylstilbestrol-supplemented ovariectomized rats (E₂ group). At 12 weeks following left ventricular blood sacrificed to detect plasma estradiol (E₂), interleukin-1β (IL-1β) and IL-6 levels. Bone mineral density (BMD) of the lumbar spine was evaluated using dual-energy X-ray absorptiometry, and the left femur proximal 1/3 slices were observed using transmission electron microscopy. Uterine wet weight and the uterus index (ratio of uterine wet weight and body weight) were compared, and the uterine endometrium was observed using a light microscope. In the OVX group, serum E₂ was significantly lower and IL-1β and IL-6 levels were significantly higher compared with the sham group. By contrast, serum E₂ levels increased and IL-1β levels decreased in the olive group, but showed no significant difference compared with the sham group. The lumbar spine BMD in the olive group was increased compared with OVX group. Electron microscopy revealed sparse collagen fibers in the OVX group, with decreased density and multi-cavity, showing pathological features of osteoporosis. By contrast, the situation was improved in the E₂ and olive groups, in which organelles such as the rough endoplasmic reticulum, mitochondria and Golgi apparatus were visible and active. Compared with the sham group rats, the uterine wet weight and uterine index decreased in the OVX and olive groups; however, no statistically significant difference was observed in the E₂ group. Furthermore, endometrial hyperplasia was not observed in the olive group, which were apparently different from E₂ group. The present results suggest that olive oil can effectively reduce bone loss in ovariectomized rats, and with no or only mild effects on the uterine endothelium.

The role of IL-1β in the bone loss during rheumatic diseases

Several inflammatory diseases have been associated with increased bone resorption and fracture rates and different studies supported the relation between inflammatory cytokines and osteoclast activity. The main factor required for osteoclast activation is the stimulation by receptor activator of nuclear factor kappa-B ligand (RANKL) expressed on osteoblasts. In this context, interleukin- (IL-) 1β, one of the most powerful proinflammatory cytokines, is a strong stimulator of in vitro and in vivo bone resorption via upregulation of RANKL that stimulates the osteoclastogenesis. The resulting effects lead to an imbalance in bone metabolism favouring bone resorption and osteoporosis. In this paper, we review the available literature on the role of IL-1β in the pathogenesis of bone loss. Furthermore, we analysed the role of IL-1β in bone resorption during rheumatic diseases and, when available, we reported the efficacy of anti-IL-1β therapy in this field.

Advanced glycation end products play adverse proinflammatory activities in osteoporosis

Osteoporosis is a major public health burden that is expected to further increase as the global population ages. In the last twenty years, advanced glycation end products (AGEs) have been shown to be critical mediators both in the pathogenesis and development of osteoporosis and other chronic degenerative diseases related to aging. The accumulation of AGEs within the bone induces the formation of covalent cross-links with collagen and other bone proteins which affects the mechanical properties of tissue and disturbs bone remodelling and deterioration, underlying osteoporosis. On the other hand, the gradual deterioration of the immune system during aging (defined as immunosenescence) is also characterized by the generation of a high level of oxidants and AGEs. The synthesis and accumulation of AGEs (both localized within the bone or in the systemic circulation) might trigger a vicious circle (in which inflammation and aging merged in the word "Inflammaging") which can establish and sustain the development of osteoporosis. This narrative review will update the molecular mechanisms/pathways by which AGEs induce the functional and structural bone impairment typical of osteoporosis.

IL-1α and IL-1β levels in blood serum and saliva of menopausal women

OBJECTIVE

The aim of this study was to examine the level of IL-1α and IL-1β in serum and saliva of postmenopausal women.

DESIGN

The study was designed to verify the possibility of using the salivary concentration of interleukin 1 as a marker in the diagnosis of osteoporosis.

MATERIALS AND METHODS

The study involved a group of 60 women during menopause-30 untreated and 30 treated with hormone replacement therapy. Patients were examined and anamnesis questionnaire was filled. Blood and saliva samples were collected. Densitometry was conducted on the femoral bone in order to compare the bone mineral density (BMD) of different research groups.

RESULTS

There were no significant differences in the concentrations of interleukins in the various research groups. The results of densitometric analysis showed a positive impact of hormone replacement therapy on the BMD (0.91-0.92 g/cm2) compared with the density in the group not treated with hormone therapy (0.77-0.8 g/cm2). There was no relationship between concentration of interleukins and the level of BMD. CONCLUSIONS. Further research on the level of cytokines in serum and saliva conducted on a broader group of patients is required. Determination of markers of bone turnover can be useful in the assessment of the treatment of metabolic bone changes.

Polymorphisms in the ALOX12 gene and osteoporosis

ALOX12 produces ligands for PPARγ thereby turning mesenchymal stem cells into adipocytes instead of osteoblasts. We investigated the effect of polymorphisms in the ALOX12 gene on BMD and fracture risk in two Danish cohorts and found four polymorphisms and a haplotype thereof to be associated with BMD and fracture risk.

INTRODUCTION

Stimulation of the PPARγ with ligands produced by the ALOX enzymes drives mesenchymal stem cells in an adipocyte direction at the expense of osteoblasts leading to decreased osteoblast number and BMD. Previously, polymorphisms in the ALOX12 gene have been associated with osteoporosis.

METHODS

We examined the effect of ALOX12 polymorphisms on BMD and the risk of fractures in two Danish cohorts: AROS, a case-control population comprising 809 individuals and DOPS, a population comprising 1,716 perimenopausal women allocated to hormone therapy or not at baseline and followed for up to 10 years. On the basis of linkage disequilibrium (LD) between SNPs throughout the gene and previous genetic association studies we chose ten polymorphisms for investigation. Genotyping was carried out using the Sequenom MassARRAY genotyping system and TaqMan assays.

RESULTS

In AROS, individuals heterozygous for the polymorphisms rs3840880, rs9897850, rs2292350 and rs1126667 had a 3.0-4.7% decreased lumbar spine BMD (p = 0.02-0.06) and an increased risk of vertebral fractures (p < 0.05) compared with individuals homozygous for either allele. In DOPS, none of the individual SNPs were associated with BMD or incident fractures. In both cohorts, the above-mentioned SNPs comprised an LD-block (pairwise D´ = 1.0, r (2) = 0.45-0.97). A haplotype comprising all the common alleles (frequency 9%) was associated with decreased bone loss at the hip (p < 0.05) and decreased incidence of osteoporotic fractures (p < 0.05) in DOPS and increased femoral neck BMD in AROS (p < 0.05).

CONCLUSION

Our study suggests that genetic variants in ALOX12 may influence BMD and fracture risk.

The association of IL-1beta, IL-2, and IL-6 gene polymorphisms with bone mineral density and osteoporosis in postmenopausal women

OBJECTIVE

Osteoporosis is a common disorder with a strong genetic component. The genetics of osteoporosis impacts on the prediction, diagnosis, prognosis, and treatment of the disease.

STUDY DESIGN

The aim of the present study was to examine associations between cytokine gene polymorphisms (IL-1beta, IL-2, IL-6) and bone mineral density (BMD) values in postmenopausal women. The study included 226 postmenopausal women with a diagnosed BMD T-score lower than -2.5 SD (mean: -3.02+/-.053) and 224 postmenopausal women with a BMD T-score greater than -2.5 SD (mean: -1.33+/-0.51).

RESULTS

Among the women with T-scores below -2.5 SD, the BMD values were significantly lower in the carriers of the IL-6 GG genotype compared with those with the CC and GC genotypes (0.70+/-0.38 vs. 0.73+/-0.25 and 0.74+/-0.23 for the lumbar spine, 0.54+/-0.18 vs. 0.56+/-0.15 and 0.58+/-0.22 for the femoral neck). There were no statistically significant associations between the IL-1beta and IL-2 genotypes and BMD values in the group of women with T-scores below -2.5 SD.

CONCLUSION

The results of the present study suggest an association of the IL-6 -174 G/C polymorphism with osteoporosis in postmenopausal women.

Associations between polymorphisms in five inflammation-related genes and cognitive ability in older persons

Several studies have found associations between inflammatory biomarker levels and cognitive ability. This study tested the relationship between polymorphisms in genes that are associated with or encode the biomarkers and cognitive ability and estimated lifetime cognitive change. Data came from the aspirin for asymptomatic atherosclerosis trial (n = 2091, mean age = 67.2 years ). Twelve single nucleotide polymorphisms (SNPs) were genotyped from five genes (IL-1alpha, IL-1beta, IL-6, HNF-1A and F13A1). Cognition was assessed via administration of a five-test battery of psychometric tests, which were used to derive a general intelligence factor, g. A vocabulary-based cognitive test was also administered and adjusted for in the analysis to enable an estimation of lifetime cognitive change. Age- and sex-adjusted analyses yielded one weakly significant association between the IL-1alpha rs2856838 SNP and a measure of mental flexibility/processing speed (P = 0.044). Adjustment for the vocabulary-based scores resulted in a single, significant association between the IL-1alpha rs3783546 SNP and a measure of processing speed (P = 0.048). There is little evidence to suggest an association between SNPs in the inflammation-related genes IL-1alpha, IL-1beta, IL-6, TCF-1 and F13A1 and cognition in an elderly population of community-dwelling Scottish citizens.

Searching for genes underlying susceptibility to osteoporotic fracture: current progress and future prospect

INTRODUCTION

Osteoporotic fracture (OF) is a public health problem. It is a common practice in the genetics of osteoporosis that bone mineral density (BMD) was studied as a major surrogate phenotype in gene search for risk of OF (ROF) because of their high phenotypic correlation. However, some studies indicate that the genetic correlation between BMD and ROF is very low. This implies that most genes found important for BMD may not be relevant to ROF. Ideally, employing OF per se as a direct study phenotype can directly find the relevant genes underlying ROF.

EVIDENCE

Here, we summarized some evidence supporting ROF under moderate genetic control, and the current progress of molecular genetic studies employing OF as the direct study phenotype, then give our consideration on the future prospects in the genetics of ROF.