In several studies, it has been shown that elevated concentrations of systemic and local pro-inflammatory cytokines, including tumor necrosis factor alpha (TNF-α), interferon-γ (IFNγ), interleukin (IL)-1β, IL-4, IL-5, IL-6, IL-13, and IL-17, present in IBD patients are potentially detrimental for bone metabolism and may be responsible for bone loss and increased fracture risk.
Here we show that cPTH fails to induce cortical and trabecular bone loss and causes less intense bone resorption in conditional knock-out (IL-17RA<sup>ΔOCY</sup> ) male and female mice lacking the expression of IL-17A receptor (IL-17RA) in dentin matrix protein 1 (DMP1)-8kb-Cre-expressing cells, which include osteocytes and some osteoblasts.
Our findings show for the first time that TREM-1 regulates the IL-17A-RANKL/OPG axis and bone loss in experimental periodontitis, and its therapeutic blockade may pave the way to a novel treatment for human periodontitis.
Treatment of Pg/Sg infected mice with BNPs reduced bone loss and IL-17 expression almost to the levels of sham-infected mice and to a greater extent than treatment with an equimolar amount of free BAR.
<i>In vivo</i>, IL-17A is not required for normal bone homeostasis but plays an important role in bone loss notably in an ovariectomized mouse model of osteoporosis.
Interleukin-17A(IL-17A), a proinflammatory cytokine, may have effects on osteoclastic resorption in inflammation-mediated bone loss, including postmenopausal osteoporosis.
The unique bone phenotype that occurs in PsA and AS is a surprising coexistence of both systemic bone loss and periosteal and entheseal bone formation and is likely to be the result of the actions of IL-23 and/or IL-17 on bone.
This study characterized the IL-17, IL-23, and TGF-β gene expression levels in healthy and diseased peri-implant tissues and correlated these data with radiographic bone loss.
T cell-produced TNF and IL-17A further contribute to bone loss in hyperparathyroidism, while T cell production of the anabolic Wingless integration site (Wnt) ligand, Wnt10b, promotes bone formation in response to anabolic parathyroid hormone and the immunomodulatory costimulation inhibitor cytotoxic T lymphocyte-associated protein-4-IgG (abatacept).
Importantly, local treatment of NHPs with Cp40 inhibited ligature-induced periodontal inflammation and bone loss, which correlated with lower gingival crevicular fluid levels of proinflammatory mediators (e.g., IL-17 and RANKL) and decreased osteoclastogenesis in bone biopsy specimens, as compared with control treatment.
The results obtained showed that the T-score in the female population with osteopenia was remarkably lower in women showing the GG genotype of -197G > A polymorphism of IL-17 gene compared to patients with heterozygous GA genotype.
We thus conclude that IL-17A is a key mediator of TNF-α-induced bone loss by closely interacting with IL-1 in blocking bone protective T-cell responses.
Since IL-17 is bone destructive in RA but a key regulator of neutrophils, we examined its role in inflammatory bone loss induced by the oral pathogen Porphyromonas gingivalis in IL-17RA-deficient mice.