Down‐regulation of expression of osteoblast and osteocyte markers in periodontal tissues associated with the spontaneous alveolar bone loss of interleukin‐10 knockout mice

Abstract

The aim of this study was to unravel the mechanisms by which interleukin (IL)-10, a potent pleiotropic cytokine, modulates alveolar bone homeostasis in C57BL/6 wild-type (WT) and IL-10 knockout (IL-10 KO) mice, evaluated at 8, 24, and 48 wk of age. Interleukin-10 KO mice presented significant alveolar bone loss when compared with WT mice, and this was not associated with changes in leukocyte counts or bacterial load. The levels of expression of messenger RNA (mRNA) for tumor necrosis factor-alpha (TNF-alpha), IL-1beta, IL-6, transforming growth factor-beta (TGF-beta), receptor activator of nuclear factor kappaB ligand (RANKL), osteoprotegerin (OPG), and matrix metalloproteinase 13 (MMP13) were similar between both strains, whereas a significant decrease of tissue inhibitor of metalloproteinase 1 (TIMP1) mRNA expression was found at 48 wk in IL-10 KO mice. The osteoblast markers core binding factor alpha1 (CBFA1) and type I collagen (COL-I) were expressed at similar levels in both strains, whereas the levels of alkaline phosphatase (ALP) and osteocalcin (OCN), and those of the osteocyte markers phosphate-regulating gene endopeptidases (PHEX) and dentin matrix protein 1 (DMP1) were significantly lower in IL-10 KO mice. Our results demonstrate that the alveolar bone loss in the absence of IL-10 was associated with a reduced expression of osteoblast and osteocyte markers, an effect independent of microbial, inflammatory or bone-resorptive pathways.

Association between Postmenopausal Osteoporosis and Experimental Periodontitis

“…Clinical researches have shown that IL-10 levels in GCF are lower in periodontitis sites, whereas the expression in healthy sites is higher [29]. Furthermore, alveolar bone loss is reportedly significant in IL-10 knockout mice [30, 31]. IL-10 has been shown to exert an inhibitory on alveolar bone resorption partly through the downregulation of the expression of IL-1 β , IL-6, and TNF- α [32–35].…”

Inflammatory Bone Loss in Experimental Periodontitis Induced by Aggregatibacter actinomycetemcomitans in Interleukin-1 Receptor Antagonist Knockout Mice

“…Each mandible was then processed for paraffin embedding, and 4-m-thick sections were obtained for each. The first section was stained with hematoxylin and eosin (H&E) for histological observations, while the next serial section was stained with tartrate-resistant acid phosphatase (TRAP) to reveal osteoclasts, which are considered to be TRAP-positive multinucleated cells (35)(36)(37). The number of osteoclasts on the interradicular septum (bone surface) (Oc.N/BS) was determined, and the osteoclast surface on the interradicular septum (bone surface) (Oc.S/BS) was evaluated, by scoring the TRAP-positive multinucleated cells attached to the bone surface as defined by Parfitt et al (38,39).…”

“…The cells were infected with A. actinomycetemcomitans in serum-free ␣-MEM containing no antibiotics. The cells were washed 3 times, cultured for 24 h in serum-free ␣-MEM, infected with viable A. actinomycetemcomitans at a multiplicity of infection (MOI) of 100, and cultured for a further 12 h in the presence of the bacteria in an incubator at 37°C under a 5% CO 2 atmosphere (35,41). After the culture periods, attached osteoblasts were collected for examination of the mRNA expression of bone resorption-related genes encoding RANKL, OPG, and M-CSF, and supernatant fluids were collected for the measurement of cytokines IL-1Ra, TNF-␣, and IL-6 produced in the supernatant.…”

Caracterização morfométrica e molecular do papel de citocinas pró e anti-inflamatórias no processo de reparo ósseo alveolar em condições homeostáticas e infecciosas

“…Este efeito está associado com a supressão da diferenciação e ativação de osteoclastos, inibindo a produção de RANKL e aumentando a de OPG (Dresner-Pollak, Gelb et al 2004;Lee, Kim et al 2008;Lorenzo, Horowitz et al 2008 (Claudino, Garlet et al 2010). …”

“…Deste modo, a perda óssea inflamatória seria resultado da ação de TNF-α sobre osteoblastos e osteoclastos (Gilbert, He et al 2000;Gilbert, He et al 2002;Katagiri and Takahashi 2002;Behl, Siqueira et al 2008;Herman, Kronke et al 2008;Lee, Kim et al 2008;Lacey, Simmons et al 2009). TNF-α ainda induz a mobilização de células precursoras de osteoclastos (monócitos) da medula óssea e sua migração para sítios de inflamação; onde TNF-α, junto com o RANKL, facilita a fusão dos monócitos, resultando nos osteoclastos que reabsorvem a matriz óssea (Katagiri and Takahashi 2002;Behl, Siqueira et al 2008;Herman, Kronke et al 2008;Lee, Kim et al 2008;Lorenzo, Horowitz et al 2008 Outra citocina analisada no presente estudo e com papel fundamental na modulação do processo de reparo foi a IL10, uma potente citocina pleiotrópica, isto é, que pode atuar em diversos tipos de células e exercer múltiplos efeitos biológicos (Volk, Asadullah et al 2001;Claudino, Garlet et al 2010;Abbas, Lichtman et al 2012). Sua ação anti-inflamatória inibe tanto uma resposta imunoproliferativa quanto uma resposta inflamatória óssea (Evans and Fox 2007;Mohamed, Sugiyama et al 2007;Menezes, Garlet et al 2008 (Owens, Gallagher et al 1996;Carmody, Schwarz et al 2002;Evans and Fox 2007).…”