23 These data suggest that increased expression of SOCS1 and SOCS3 may represent a mechanism of negative regulation in response to activity of STAT1 and STAT3, and may be an important Pexidartinib mechanism in regulating expression of genes associated with degradation of connective tissue and alveolar bone resorption. Even though deletion of SOCS1 and SOCS3 genes in mice is lethal,24 it is tempting to speculate that in the absence of this endogenous regulatory mechanism the host response would be exacerbated in terms of severity and duration, with a major increase on the activation of STATs. In these conditions, inflammatory cytokine expression and tissue destruction

associated with periodontal diseases and other conditions associated with chronic inflammation, would be severely aggravated. Experiments in transgenic animals with tissue-specific deletion of these genes will define their relevance for the immune response. In addition to directly modulating tissue destruction,

SOCS could also impact periodontitis buy AZD2281 outcome through the modulation of healing process. Indeed, in vivo studies demonstrate the importance of SOCS3 in negative modulation of gp130/STAT3 signaling pathway in wound healing. The absence of SOCS3 leads to an increased activity of STAT3 causing delay in healing. 25 and 26 In our study, we found that even after 30 days of ligature placement, mRNA and protein levels of SOCS3 remain elevated in spite of the decrease on the severity

of inflammation. In fact, the apical migration of the junctional epithelium increasing the distance to the site of aggression CYTH4 located on the gingival margin reduced the aggression and consequently decreased the severity of the inflammatory infiltrate. This may be followed by an attempt to repair the damaged tissues, which is characterised by the tendency to increase the number of fibroblasts and extracellular matrix verified by stereometry. This interpretation is supported by the fact that once placed, ligatures were kept throughout the 30-day experimental period; however they were not pushed further apically even if the gingival margin receded. This suggests that SOCS3 may also participate in the healing of periodontal tissues. To our knowledge, this is the first study to describe the kinetic profile of SOCS1 and SOCS3 expression during experimental periodontal disease, and its association with STAT activation profile. Additional studies will include gain and loss of function experiments to determine the role of these proteins in the modulation of host response associated with chronic inflammation and also to verify possible novel targets of SOCS proteins for direct protein–protein interactions. In summary, our study shows the kinetics of SOCS1 and SOCS3 mRNA and protein expression in the experimental model of ligature-induced periodontal disease.