Lactoferrin promote primary rat osteoblast proliferation and differentiation via up-regulation of insulin-like growth factor-1 expression.

The aim of this study was to explore the effect of lactoferrin (LF) in primary fetal rat osteoblasts proliferation and differentiation and investigate the underlying molecular mechanisms. Primary rat osteoblasts were obtained from the calvarias of neonatal rats. Osteoblasts were treated with LF (0.1-1000 µg/mL), or OSI-906 [a selective inhibitor of insulin-like growth factor 1 (IGF-1) receptor and insulin receptor]. The IGF-1 was then knocked down by small hairpin RNA (shRNA) technology and then was treated with recombinant human IGF-1 or LF. Cell proliferation and differentiation were measured by MTT assay and alkaline phosphatase (ALP) assay, respectively. The expression of IGF-1 and IGF binding protein 2 (IGFBP2) mRNA were analyzed using real-time PCR. LF promotes the proliferation and differentiation of osteoblasts in a certain range (1-100 µg/mL) in time- and dose-dependent manner. The mRNA level of IGF-1 was significantly increased, while the expression of IGFBP2 was suppressed by LF treatment. Knockdown of IGF-1 by shRNA in primary rat osteoblast dramatically decreased the abilities of proliferation and differentiation of osteoblasts and blocked the proliferation and differentiation effect of LF in osteoblasts. OSI906 (5 µM) blocked the mitogenic and differentiation of LF in osteoblasts. Proliferation and differentiation of primary rat osteoblasts in response to LF are mediated in part by stimulating of IGF-1 gene expression and alterations in the gene expression of IGFBP2.

Lactoferrin inhibits apoptosis through insulin-like growth factor I in primary rat osteoblasts.

AIM: Excessive apoptosis of osteoblasts is the major cause of low bone mass, and bovine lactoferrin (bLF), an iron-binding glycoprotein, might protect osteoblastic cells from apoptosis induced by serum withdrawal. The aim of this study was to elucidate the mechanisms underlying the anti-apoptotic action of bLF in rat osteoblasts in vitro. METHODS: Primary rat osteoblasts were incubated in the presence of varying concentrations of bLF for 24 h. The expression of insulin-like growth factor I (IGF-I) and IGF-I receptor (IGF-IR) was measured uisng RT-PCR and Western blotting. Cell apoptosis was examined with flow cytometry. siRNAs targeting IGF-I was used in this study. RESULTS: Treatment of bLF (0.1-1000 µg/mL) dose-dependently increased the expression of IGF-I and IGF-IR in the osteoblasts. Treatment with bLF (10, 100 µg/mL) markedly inhibited the osteoblast apoptosis (with the rate of total apoptosis of 70% at 10 µg/mL), but the high concentration of bLF (1000 µg/mL) significantly promoted the osteoblast apoptosis. Knockdown of the IGF-I gene in osteoblasts with siRNA markedly increased the osteoblast apoptosis. CONCLUSION: Lactoferrin (10 and 100 µg/mL) effectively inhibits apoptosis of primary rat osteoblasts by upregulating IGF-I expression.

Gas-phase and PM2.5-bound phthalates in nail salons: characteristics, exposure via inhalation, and influencing factors.

This study aimed to investigate the characteristics of, exposure to, and factors influencing gas-phase and PM2.5-bound phthalates (PAEs) in nail salons. Data on both indoor and outdoor gas-phase and PM2.5-bound PAEs, carbon dioxide (CO2), temperature, and relative humidity were collected in nail salons. We also used questionnaires to survey building characteristics and occupants' behaviors. The average total gas-phase and PM2.5-bound PAE concentrations indoors were higher than those outdoors by 6 and 3 times, respectively. Diethyl phthalate, diisobutyl phthalate (DiBP), di-n-butyl phthalate (DnBP), and di-(2-ethylhexyl) phthalate (DEHP) were the predominant compounds among both the gas-phase and PM2.5-bound PAEs in indoor air. The volume of the salon's space or the difference of indoor and outdoor CO2 concentrations (dCO2) was significantly associated with indoor PAE concentrations. The ratios of PM2.5-bound to gas-phase PAEs, especially high-molecular-weight PAEs, were positively associated with the dCO2 concentrations. Higher ratios of indoor to outdoor PM2.5-bound DiBP, DnBP, and DEHP concentrations were discovered when more clients visited each day. Building characteristics, ventilation conditions, and occupants' activities have influences on the gas-phase and particle-phase PAEs. The study identifies the characteristics of gas-phase and PM2.5-bound PAEs in nail salons and their influencing factors.

Characteristics and influencing factors of airborne microplastics in nail salons.

Airborne microplastic particles (MPs) are emerging contaminants. Although some studies have investigated the characteristics of indoor MPs in homes or offices, information regarding MPs in nail salons with potentially higher MP pollution is unavailable. In this study, we collected indoor and outdoor air samples from nail salons to analyze the concentrations, physical characteristics, and polymers of MPs and further assessed the exposure through inhalation and influencing factors. Our data displayed that the average indoor MP concentration was 46 ± 55 MPs/m3. The estimated average annual exposure to indoor MPs was 67,567 ± 81,782 MPs/year. The predominant shape and size of indoor MPs were fragment and <50 µm, respectively. The predominant polymer in indoor air was acrylic (27%), followed by rubber (21%), and polyurethane (13%). Air conditioner, nail treatment, ceiling and flooring with plastic materials, and number of occupants were factors affecting indoor MP concentrations. We concluded that MP pollution was more severe in nail salons and the physical characteristics and polymer compositions differed between nail salons and other indoor spaces reported in other studies. Air conditioner usage induced higher MP emission, and higher MP concentrations were observed in nail salons with plastic ceiling and flooring or more occupants.

Lactoferrin Induces Osteoblast Growth through IGF-1R.

Objectives. To investigate the role of the IGF-1R by which lactoferrin induces osteoblast growth. Methods. Osteoblast received 5 d lactoferrin intervention at a concentration of 0.1, 1, 10, 100, and 1000 µg/mL, and the IGF-1 and IGF-1R were detected using RT-PCR and western blot. The osteoblast into the control, 100 µg/mL lactoferrin, Neo-scramble (NS, empty vector), NS + 100 µg/mL lactoferrin, shIGF-1R and shIGF-1R + 100 µg/mL lactoferrin group. We test the apoptosis and proliferation and the level of PI3K and RAS in osteoblasts after 5 d intervention. Results. (1) 1, 10, 100, and 1000 µg/mL lactoferrin induced the expression of IGF-1 mRNA and protein. 10 µg/mL and 100 µg/mL lactoferrin induced the expression of IGF-1R mRNA and protein. (2) Lactoferrin (100 µg/mL) induced osteoblast proliferation while inhibiting apoptosis. Osteoblasts with silenced IGF-1R exhibited decreased proliferation but increased apoptosis. MMT staining and flow cytometry both indicated that there was no significant difference between the shIGF-1R group and the shIGF-1R + 100 µg/mL lactoferrin group. (3) Lactoferrin (100 µg/mL) induced PI3K and RAS phosphorylation and silence of IGF-1R resulted in decreased p-PI3K and p-RAS expression. Lactoferrin-treated shIGF-1R cells showed significantly higher level of p-PI3K and p-RAS when compared with shIGF-1R. Conclusion. Lactoferrin induced IGF-1/IGF-1R in a concentration-dependent manner. Lactoferrin promoted osteoblast proliferation while inhibiting apoptosis through IGF-1R. Lactoferrin activated PI3K and RAS phosphorylation via an IGF-1R independent pathway.