BACKGROUND: This study aimed to investigate the effect of erbium, chromium doped:yttrium,scandium,gallium,garnet (Er,Cr:YSGG) laser application combined with non-surgical mechanical debridement (MD) on clinical parameters and peri-implant crevicular fluid receptor activator of nuclear factor-kappa B ligand (RANKL) and osteoprotegerin (OPG) levels in the treatment of peri-implantitis.
METHODS: A total of 49 patients who underwent non-surgical treatment of peri-implantitis were randomly divided into two groups. The control group (n = 26) received MD alone, while the laser group (n = 23) received MD+Er,Cr:YSGG. The clinical parameters (bleeding on probing [BoP], gingival index [GI], plaque index [PI], probing depth [PD]), marginal bone loss (MBL), and biochemical parameters (RANKL and OPG) were measured at baseline (T0) and 6 months after treatment (T1).
RESULTS: There was a statistically significant decrease in all the clinical parameters in both groups at T1 compared to T0 (p < 0.05). The BoP, PD, MBL, and RANKL reductions were significantly higher in the laser group than in the control group (p = 0.046, p = 0.014, p = 0.047, p = 0.045, respectively). The OPG levels significantly increased at T1 in the laser group (p = 0.01). The OPG/RANKL ratio increased significantly in both groups at T1, which favored the laser group (p = 0.034).
CONCLUSIONS: Although both treatment methods were influential in treating peri-implantitis, the laser group (MD+Er,Cr:YSGG) yielded more favorable results by reducing clinical inflammation and improving biochemical parameters. Based on these findings, Er,Cr:YSGG laser may be a beneficial adjunctive treatment in this patient group.

This study evaluated the effect of photobiomodulation therapy (PBMT) using 660 and 808 nm diode lasers (individual and in combination) on periodontal ligament mesenchymal stem cells (PDLSCs) in the presence of zoledronic acid (ZA). PDLSCs were cultured for 48 h in DMEM complete medium containing 5 μM ZA. PBMT was done three times with a 24-h interval in groups 1 (660 nm, 5 J/cm2 ), 2 (880 nm, 3 J/cm2 ), and 3 (660 + 808 nm) either in normal or ZA-treated culture medium. Control groups did not receive PBMT. Twenty-four hours post-irradiation, cell proliferation and expression of RANKL and OPG were assessed using MTT and real-time PCR tests, respectively. The results showed a significant decrease in cell viability in ZA-treated cells (p < 0.001). Additionally, ZA induced the expression of OPG (p = 0.03) while reducing RANKL (p < 0.001). Cell proliferation was significantly increased in 808 and 660 + 808 nm groups. Moreover, all PBMT groups could significantly increase and decrease the RANKL and OPG, respectively, in the presence of ZA (all p < 0.001). A combination of 660 + 808 nm showed the highest effects on both genes. In conclusion, it seems that PBMT can modulate the effects of ZA by inducing PDLSC proliferation and increasing RANKL-to-OPG gene expression ratio.

Denosumab is a monoclonal antibody blocking the receptor activator of nuclear factor kappa-B/receptor activator of nuclear factor kappa-B ligand (RANK/RANKL) pathway, thus inhibiting osteoclastogenesis. Since RANK and RANKL are also involved in the immune system activation, denosumab might interfere with the response against infections. Our study aimed to explore the relationship between denosumab treatment and coronavirus disease 2019 (COVID-19).
The occurrence and severity of COVID-19 were recorded in consecutive patients referred to the Endocrinology Department of Papa Giovanni XXIII Hospital, Bergamo, from 1 January 2020 to 1 January 2021. Patients treated with denosumab were compared to outpatient controls. Patients\' features were summarized by descriptive statistics. Multivariate logistic regression assessed the relationship between denosumab and COVID-19, adjusting for potential confounders. Subgroup analyses according to age, sex, body mass index (BMI), smoking status, and vitamin D levels were performed.
The final population included 331 patients treated with denosumab and 357 controls. COVID-19 incidence was lower in the denosumab group (7.6% vs. 14.6%, p = 0.004). COVID-19 severity was similar in both groups. Multiple logistic regression confirmed an association between denosumab and a reduced occurrence of symptomatic COVID-19 [odds ratio (OR) 0.46, 95% CI 0.21-0.98, p = 0.049]. Subgroup analyses suggested a potential protective effect of denosumab in patients over 75 years (OR 0.12, 95% CI 0.02-0.6, p = 0.011), with a significant interaction between denosumab and age categories (p = 0.047).
Our study confirms that denosumab may be safely continued in COVID-19 patients. RANK/RANKL inhibition seems associated with a reduced incidence of symptomatic COVID-19, particularly among the elderly.

BACKGROUND: Participants with prediabetes are at a high risk of developing type 2 diabetes (T2D). Recent studies have suggested that blocking the receptor activator of nuclear factor-κB ligand (RANKL) may improve glucose metabolism and delay the development of T2D. However, the effect of denosumab, a fully human monoclonal antibody that inhibits RANKL, on glycemic parameters in the prediabetes population is uncertain. We aim to examine the effect of denosumab on glucose metabolism in postmenopausal women with osteoporosis and prediabetes.
METHODS: This is a 12-month multicenter, open-label, randomized controlled trial involving postmenopausal women who have been diagnosed with both osteoporosis and prediabetes. Osteoporosis is defined by the World Health Organization (WHO) as a bone mineral density T score of ≤ - 2.5, as measured by dual-energy X-ray absorptiometry (DXA). Prediabetes is defined as (i) a fasting plasma glucose level of 100-125 mg/dL, (ii) a 2-hour plasma glucose level of 140-199 mg/dL, or (iii) a glycosylated hemoglobin A1c (HbA1c) level of 5.7-6.4%. A total of 346 eligible subjects will be randomly assigned in a 1:1 ratio to receive either subcutaneous denosumab 60 mg every 6 months or oral alendronate 70 mg every week for 12 months. The primary outcome is the change in HbA1c levels from baseline to 12 months. Secondary outcomes include changes in fasting and 2-hour blood glucose levels, serum insulin levels, C-peptide levels, and insulin sensitivity from baseline to 12 months, and the incidence of T2D at the end of the study. Follow-up visits will be scheduled at 3, 6, 9, and 12 months.
CONCLUSIONS: This study aims to provide evidence on the efficacy of denosumab on glucose metabolism in postmenopausal women with osteoporosis and prediabetes. The results derived from this clinical trial may provide insight into the potential of denosumab in preventing T2D in high-risk populations.
BACKGROUND: This study had been registered in the Chinese Clinical Trials Registry.
BACKGROUND: ChiCTR2300070789 on April 23, 2023. https://www.chictr.org.cn .

BACKGROUND: Diabetes mellitus (DM)-associated hyperinflammatory host response significantly provokes periodontal tissue destruction. In this context, the support of nonsurgical periodontal therapy in diabetics with host modulation agents is a current field of study. This clinical study aims to investigate the clinical efficacy of melatonin supplementation and discuss its possible biological mechanisms in nonsurgical periodontal treatment in patients with DM and periodontitis through some fundamental markers.
METHODS: In this randomized controlled and single-blind study, 27 of 55 diabetic patients with periodontitis (stage III/IV and grade C) underwent full-mouth scaling and root planing (fmSRP) alone and 28 patients underwent melatonin administration (6 mg daily, 30 days) in addition to fmSRP (full-mouth scaling and root planing plus melatonin, fmSRP-mel). The potential therapeutic contribution of melatonin was evaluated clinically and biochemically (gingival crevicular fluid RANKL, OPG, MMP-8, and serum IL-1β levels) at 3rd and 6th months.
RESULTS: Melatonin (tablet, 6 mg daily, 30 days) did not cause any local or systemic side effects. fmSRP alone resulted in significant reduction in serum IL-1β levels, pocket depths, gingival inflammation, and gingival crevicular fluid RANKL and MMP-8 levels (p < 0.05). Moreover, melatonin supplementation resulted in a more significant decrease in bleeding and pocket depth scores at probing, especially at 3 months (p < 0.05). Furthermore, RANKL and MMP-8 levels were significantly lower at 3 months and IL-1β levels at 6 months compared to the control group (p < 0.05). However, OPG levels were not affected significantly by the treatments (p > 0.05).
CONCLUSIONS: Melatonin, as a host modulation agent, significantly increases the clinical efficacy of fmSRP. The reduction in periodontal inflammation and pocket depths may be a result of marked suppression of RANKL-associated osteoclastogenesis and extracellular matrix damage by melatonin.

Progesterone receptor (PR) signaling is required for mammary gland development and homeostasis. A major bottleneck in studying PR signaling is the lack of sensitive assays to measure and visualize PR pathway activity both quantitatively and spatially. Here, we develop new tools to study PR signaling in human breast epithelial cells. First, we generate optimized Progesterone Responsive Element (PRE)-luciferase constructs and demonstrate that these new reporters are a powerful tool to quantify PR signaling activity across a wide range of progesterone concentrations in two luminal breast cancer cell lines, MCF7 and T47D. We also describe a fluorescent lentiviral PRE-GFP reporter as a novel tool to visualize PR signaling at the single-cell level. Our reporter constructs are sensitive to physiological levels of progesterone. Second, we show that low background signaling, and high levels of PR expression are a prerequisite for robustly measuring PR signaling. Increasing PR expression by transient transfection, stable overexpression in MCF7 or clonal selection in T47D, drastically improves both the dynamic range of luciferase reporter assays, and the induction of endogenous PR target genes as measured by qRT-PCR. We find that the PR signaling response differs per cell line, target gene and hormone concentration used. Taken together, our tools allow a more rationally designed approach for measuring PR signaling in breast epithelial cells.

Diabetic osteoporosis (DOP) is a diabetic complication associated with a significant disability rate. Liraglutide, a glucagon-like peptide-1 receptor agonist, is a promising and innovative drug for type 2 diabetes mellitus (T2DM), with potential therapeutic implications for bone disorders. This investigation examined the impact of liraglutide on osteoporosis in rats with T2DM and studied the influence of vitamin D receptor Bsm1 polymorphism on liraglutide-induced outcomes. Thirty rats were divided into control, T2DM induced by a combination of a high-fat diet and 25 mg/kg streptozotocin, and T2DM-liraglutide (T2DM treated with 0.4 mg/kg/day liraglutide) groups. After 8 weeks of liraglutide treatment, femurs and blood samples were obtained from all rats for subsequent investigations. Diabetes induced a remarkable rise in the serum levels of receptor activator of nuclear factor kappa B ligand (RANKL) and C-telopeptide of type I collagen (CTX-1) associated with a remarkable decline in osteocalcin and osteoprotegerin (OPG). Impaired bone architecture was also demonstrated by light and scanning electron microscopic study. The immune expression of OPG was down-regulated, while RANKL was up-regulated. Interestingly, the administration of liraglutide ameliorated the previous changes induced by diabetes mellitus. In conclusion, liraglutide can prevent DOP, mostly due to liraglutide\'s ability to increase bone growth, while inhibiting bone resorption.

OBJECTIVE: The aim of this study was to monitor changes in Osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa ligand (RANKL) levels in the saliva during orthodontic tooth movement (OTM).
METHODS: Nine healthy females (15-20 y of age) with four pre-molar extractions and fixed appliance were included. In total, 134 stimulated and 134 unstimulated saliva samples were collected: at baseline and then every 6-8 weeks at follow-up appointments during the whole orthodontic treatment. Twelve age-matched females with no active orthodontic treatment served as a control group. Saliva samples were analysed by enzyme-linked immunosorbent assay (Elisa). The mean levels of OPG and RANKL were calculated according to the different orthodontic treatment stages: alignment, space closure and finishing. A mixed model analysis was used to compare the means of treatment stages. Baseline OPG levels were compared with the control group using an independent t-test. OPG levels were measured in stimulated saliva due to low levels in unstimulated saliva.
RESULTS: No significant difference was observed between baseline OPG values and the control group. OPG increased significantly at all treatment stages: alignment, space closure and finishing compared with baseline (P = 0.002, P = 0.039, P ≤ 0.001, respectively). The salivary levels of OPG increased gradually, except during space closure, reaching peak levels at finishing. RANKL was undetectable in stimulated and unstimulated saliva by sandwich Elisa during OTM.
CONCLUSIONS: This novel approach shows the changes in the levels of OPG in OTM and indicates how and when to sample saliva during orthodontic treatment to analyse bone remodelling.

BACKGROUND: Increased RANKL expression is observed in the bone tissue of fibrous dysplasia of bone/McCune-Albright syndrome (FD/MAS). In one animal model of FD/MAS, the inhibition of RANKL reduced tumor volume. A beneficial effect of denosumab on pain in patients refractory to bisphosphonates has been reported, but without systematic quantification of pain improvement. This work describes the clinical experience of our group on the efficacy on pain of denosumab treatment, along with safety, in FD/MAS patients refractory to bisphosphonates.
METHODS: We have conducted a retrospective multicenter study in 6 academic rheumatology centers in France. We have collected patients and FD/MAS characteristics, duration of prior exposure to bisphosphonates, denosumab treatment modalities (dosage - administration regimen - number of courses); evolution of pain evaluated by Visual Analogic Scale (VAS).
RESULTS: 13 patients were included (10 women and 3 men) 45 years on average, 5 MAS, 4 monostotic and 4 polyostotic forms. The average duration post-diagnosis of FD/MAS was 25 years and the mean duration of prior exposure to bisphosphonates was 4.7 years. Pain could be analyzed in 7 patients, showing a significant improvement from a mean VAS of 7.8 to 2.9 (-4.9 points, p = 0.003). In one patient with fronto-orbital FD/MAS, a 30 % decrease in lesional volume, assessed by MRI, was observed within 6 months of treatment, that was sustained over the following 12 months. Treatment regimens were heterogeneous. No hypercalcemia was observed after treatment cessation and the clinical tolerance was good.
CONCLUSIONS: This study suggests that denosumab reduces pain in patients with DF/MAS refractory to bisphosphonates, and quantifies this improvement for the first time in a multicenter study. In our cohort, no patients who discontinued denosumab developed hypercalcemia and clinical tolerance was overall good. This study also provides encouraging data regarding lesion volume control. Further controlled studies are required to determine the place and modalities of the denosumab treatment of FD/MAS.
CONCLUSIONS: Denosumab significantly decreased pain in FD/MAS refractory to bisphosphonate. This study paves the way for a randomized clinical trial to validate and standardize the prescription of denosumab in FD/MAS.

UNASSIGNED: Osteoclastogenesis, the process of osteoclast differentiation, plays a critical role in bone homeostasis. Overexpression of osteoclastogenesis can lead to pathological conditions, such as osteoporosis and osteolysis. This study aims to investigate the role of Engelitin in the process of RAW264.7 cell differentiation into osteoclasts induced by RANKL, as well as in a mouse model of bone loss following ovariectomy.
UNASSIGNED: We used RANKL-stimulated RAW264.7 cells as an in vitro osteoclast differentiation model. The effects of Eng on morphological changes during osteoclast differentiation were evaluated using TRAP and F-actin staining. The effects of Eng on the molecular level of osteoclast differentiation were evaluated using Western blot and q-PCR. The level of reactive oxygen species was evaluated using the DCFH-DA staining method. We then used ovariectomized mice as a bone loss animal model. The effects of Eng on changes in bone loss in vivo were evaluated using micro-CT and histological analysis staining.
UNASSIGNED: In the in vitro experiments, Eng exhibited dose-dependent inhibition of osteoclast formation and F-actin formation. At the molecular level, Eng dose-dependently suppressed the expression of specific RNAs (NFATc1, c-Fos, TRAP, Cathepsin K, MMP-9) involved in osteoclast differentiation, and inhibited the phosphorylation of proteins such as IκBα, P65, ERK, JNK, and P38. Additionally, Eng dose-dependently suppressed ROS levels and promoted the expression of antioxidant enzymes such as Nrf2, HO-1, and NQO1. In the in vivo experiments, Eng improved bone loss in ovariectomized mice.
UNASSIGNED: Our study found that Eng inhibited RANKL-induced osteoclast differentiation through multiple signaling pathways, including MAPKs, NF-κB, and ROS aggregation. Furthermore, Eng improved bone loss in ovariectomized mice.