Selective inhibition of interleukin 6 receptor decreased inflammatory cytokines and increased proteases in an experimental model of critical calvarial defect.

Considering the lack of consensus related to the impact of selective IL-6 receptor inhibition on bone remodeling and the scarcity of reports, especially on large bone defects, this study proposed to evaluate the biological impact of the selective inhibitor of interleukin-6 receptor (tocilizumab) in an experimental model of critical calvarial defect in rats. In this preclinical and in vivo study, 24 male Wistar rats were randomly divided into two groups (n=12/group): defect treated with collagen sponge (CG) and defect treated with collagen sponge associated with 2 mg/kg tocilizumab (TCZ). The defect in the parietal bone was created using an 8-mm diameter trephine drill. After 90 days, the animals were euthanized, and tissue samples (skull caps) were evaluated through micro-CT, histological, immunohistochemistry, cytokines, and RT-qPCR analyses. Tocilizumab reduced mononuclear inflammatory infiltration (P<0.05) and tumor necrosis factor (TNF)-α levels (P<0.01) and down-regulated tissue gene expression of BMP-2 (P<0.001), RUNX-2 (P<0.05), and interleukin (IL)-6 (P<0.05). Moreover, it promoted a stronger immunostaining of cathepsin and RANKL (P<0.05). Micro-CT and histological analyses revealed no impact on general bone formation (P>0.05). The bone cells (osteoblasts, osteoclasts, and osteocytes) in the defect area were similar in both groups (P>0.05). Tocilizumab reduced inflammatory cytokines, decreased osteogenic protein, and increased proteases in a critical bone defect in rats. Ninety days after the local application of tocilizumab in the cranial defect, we did not find a significant formation of bone tissue compared with a collagen sponge.

Selective inhibition of interleukin 6 receptor decreased inflammatory cytokines and increased proteases in an experimental model of critical calvarial defect

Considering the lack of consensus related to the impact of selective IL-6 receptor inhibition on bone remodeling and the scarcity of reports, especially on large bone defects, this study proposed to evaluate the biological impact of the selective inhibitor of interleukin-6 receptor (tocilizumab) in an experimental model of critical calvarial defect in rats. In this preclinical and in vivo study, 24 male Wistar rats were randomly divided into two groups (n=12/group): defect treated with collagen sponge (CG) and defect treated with collagen sponge associated with 2 mg/kg tocilizumab (TCZ). The defect in the parietal bone was created using an 8-mm diameter trephine drill. After 90 days, the animals were euthanized, and tissue samples (skull caps) were evaluated through micro-CT, histological, immunohistochemistry, cytokines, and RT-qPCR analyses. Tocilizumab reduced mononuclear inflammatory infiltration (P<0.05) and tumor necrosis factor (TNF)-α levels (P<0.01) and down-regulated tissue gene expression of BMP-2 (P<0.001), RUNX-2 (P<0.05), and interleukin (IL)-6 (P<0.05). Moreover, it promoted a stronger immunostaining of cathepsin and RANKL (P<0.05). Micro-CT and histological analyses revealed no impact on general bone formation (P>0.05). The bone cells (osteoblasts, osteoclasts, and osteocytes) in the defect area were similar in both groups (P>0.05). Tocilizumab reduced inflammatory cytokines, decreased osteogenic protein, and increased proteases in a critical bone defect in rats. Ninety days after the local application of tocilizumab in the cranial defect, we did not find a significant formation of bone tissue compared with a collagen sponge.

Diabetes Activates Periodontal Ligament Fibroblasts via NF-κB In Vivo.

Diabetes mellitus increases periodontitis and pathogenicity of the oral microbiome. To further understand mechanisms through which diabetes affects periodontitis, we examined its impact on periodontal ligament fibroblasts in vivo and in vitro. Periodontitis was induced by inoculation of Porphyromonas gingivalis and Fusobacterium nucleatum in normoglycemic and diabetic mice. Diabetes, induced by multiple low-dose injections of streptozotocin increased osteoclast numbers and recruitment of neutrophils to the periodontal ligament, which could be accounted for by increased CXC motif chemokine 2 (CXCL2) and receptor activator of nuclear factor kappa B ligand (RANKL) expression by these cells. Diabetes also stimulated a significant increase in nuclear factor kappa B (NF-κB) expression and activation in periodontal ligament (PDL) fibroblasts. Surprisingly, we found that PDL fibroblasts express a 2.3-kb regulatory unit of Col1α1 (collagen type 1, alpha 1) promoter typical of osteoblasts. Diabetes-enhanced CXCL2 and RANKL expression in PDL fibroblasts was rescued in transgenic mice with lineage-specific NF-κB inhibition controlled by this regulatory element. In vitro, high glucose increased NF-κB transcriptional activity, NF-κB nuclear localization, and RANKL expression in PDL fibroblasts, which was reduced by NF-κB inhibition. Thus, diabetes induces changes in PDL fibroblast gene expression that can enhance neutrophil recruitment and bone resorption, which may be explained by high glucose-induced NF-κB activation. Furthermore, PDL fibroblasts express a regulatory element in vivo that is typical of committed osteoblasts.