Alendronate regulates cytokine production induced by lipid A through nuclear factor-κB and Smad3 activation in human gingival fibroblasts

In Vitro Cytotoxicity of Antiresorptive and Antiangiogenic Compounds on Oral Tissues Contributing to MRONJ: Systematic Review

BACKGROUND

Invasive dental treatment in patients exposed to antiresorptive and antiangiogenic drugs can cause medication-related osteonecrosis of the jaw (MRONJ). Currently, the exact pathogenesis of this disease is unclear.

METHODS

In March 2022, Medline (Ovid), Embase (Ovid), Scopus, and Web of Science were screened to identify eligible in vitro studies investigating the effects of antiresorptive and antiangiogenic compounds on orally derived cells.

RESULTS

Fifty-nine articles met the inclusion criteria. Bisphosphonates were used in 57 studies, denosumab in two, and sunitinib and bevacizumab in one. Zoledronate was the most commonly used nitrogen-containing bisphosphonate. The only non-nitrogen-containing bisphosphonate studied was clodronate. The most frequently tested tissues were gingival fibroblasts, oral keratinocytes, and alveolar osteoblasts. These drugs caused a decrease in cell proliferation, viability, and migration.

CONCLUSIONS

Antiresorptive and antiangiogenic drugs displayed cytotoxic effects in a dose and time-dependent manner. Additional research is required to further elucidate the pathways of MRONJ.

Dynamic expression of SMAD3 is critical in osteoblast differentiation of PDMCs

Human pluripotent stem cells have the potential assist in the identification of genes involved in mammalian development. The human placenta is considered a repository of stem cells, termed placenta‑derived multipotent cells (PDMCs), which are able to differentiate into cells with an osteoblastic phenotype. This plasticity of PDMCs maybe applied clinically to the understanding of osteogenesis and osteoporosis. In the presentstudy, osteoblasts were generated by culturing PDMCs in osteogenic medium. Reverse transcription quantitative polymerase chain reactionand the degree of osteoblast calcification were used to evaluate the efficacy of osteogenesis. The results suggestedthat the expression of mothers against decapentaplegic homolog 3 (SMAD3) increased in the initial stages of osteogenic differentiation but decreased in the later stages. However, osteogenesis was inhibitedwhen the PDMCs overexpressed SMAD3 throughout the differentiation period. In addition, the rate of osteogenic differentiation was decreased when SMAD3 signaling was impaired. In conclusion, SMAD3 serves an important role in osteoblast differentiation and bone formation in a time‑dependent manner. The data from the present study indicate that arapid increase in SMAD3 expression is crucial for osteogenesis and suggest a role for PDMCs in the treatment of patients with osteoporosis.

Risk of atrial fibrillation among bisphosphonate users: a multicenter, population-based, Italian study

Bisphosphonate treatment is used to prevent bone fractures. A controversial association of bisphosphonate use and risk of atrial fibrillation has been reported. In our study, current alendronate users were associated with a higher risk of atrial fibrillation as compared with those who had stopped bisphosphonate (BP) therapy for more than 1 year.

INTRODUCTION

Bisphosphonates are widely used to prevent bone fractures. Controversial findings regarding the association between bisphosphonate use and the risk of atrial fibrillation (AF) have been reported. The aim of this study was to evaluate the risk of AF in association with BP exposure.

METHODS

We performed a nested case-control study using the databases of drug-dispensing and hospital discharge diagnoses from five Italian regions. The data cover a period ranging from July 1, 2003 to December 31, 2006. The study population comprised new users of bisphosphonates aged 55 years and older. Patients were followed from the first BP prescription until an occurrence of an AF diagnosis (index date, i.e., ID), cancer, death, or the end of the study period, whichever came first. For the risk estimation, any AF case was matched by age and sex to up to 10 controls from the same source population. A conditional logistic regression was performed to obtain the odds ratio with 95% confidence intervals (CI). The BP exposure was classified into current (<90 days prior to ID), recent (91-180), past (181-364), and distant past (≥365) use, with the latter category being used as a reference point. A subgroup analysis by individual BP was then carried out.

RESULTS

In comparison with distant past users of BP, current users of BP showed an almost twofold increased risk of AF: odds ratio (OR) = 1.78 and 95% CI = 1.46-2.16. Specifically, alendronate users were mostly associated with AF as compared with distant past use of BP (OR, 1.97; 95% CI, 1.59-2.43).

CONCLUSION

In our nested case-control study, current users of BP are associated with a higher risk of atrial fibrillation as compared with those who had stopped BP treatment for more than 1 year.

Amphotericin B up-regulates lipid A-induced IL-6 production via caspase-8

Amphotericin B, an antifungal drug used to treat candidiasis, has been reported to induce pro-inflammatory cytokine production in cultured cells. This study investigated the effects of amphotericin B on pro-inflammatory cytokine production in response to lipid A, the bioactive component of lipopolysaccharide (LPS) in the cell walls of Gram-negative bacteria. Amphotericin B alone elicited a slight increase in interleukin (IL)-6 and IL-8 production by human gingival fibroblasts. However, amphotericin B synergistically up-regulated lipid A-induced production of IL-6 and IL-8. While amphotericin B minimally activated nuclear factor (NF)-κB, it synergistically increased lipid A-induced NF-κB activation. Pre-treatment with methyl-β-cyclodextrin (MβCD), a cholesterol-binding agent, reduced IL-6 and IL-8 production in human gingival fibroblasts. Cholesterol-saturated MβCD also reversed cytokine production, suggesting that the synergistic production of cytokines by amphotericin B and lipid A is dependent on cholesterol-rich microdomains. Amphotericin B activated caspase-8. In addition, a caspase-8 inhibitor inhibited IL-6 production by amphotericin B and lipid A. This suggests that caspase-8 is required for the synergistic production of IL-6 by amphotericin B and lipid A. Collectively, our results suggest that periodontal treatment carried out before amphotericin B treatment may protect against lipid A-induced pro-inflammatory cytokine production.

Candida albicans enhances invasion of human gingival epithelial cells and gingival fibroblasts by Porphyromonas gingivalis

Although Candida albicans has been isolated from periodontal pockets, its relationship to periodontitis is unclear. In this study, we investigated the effect of C. albicans on the adhesion and invasion of Ca9-22, a human gingival epithelial cell line, and human gingival fibroblasts by Porphyromonas gingivalis. Heat-killed C. albicans and water-soluble mannoprotein-β-glucan complex from C. albicans (CAWS) did not enhance P. gingivalis adhesion or upregulate the expression of β1 integrin and ICAM-1, which are required for P. gingivalis invasion; both the epithelial cells and fibroblasts expressed dectin-1, which recognizes components of the C. albicans cell wall. However, pretreatment of Ca9-22 cells and human gingival fibroblasts with heat-killed C. albicans or CAWS significantly enhanced P. gingivalis invasion. These results suggest that C. albicans may exacerbate infectious disease by enhancing the invasion of host cells by anaerobic bacteria.