5). The stereometric analysis supports these

results, as the density of inflammatory cells decreased at days Belnacasan in vivo 15 and 30 (Fig. 1 and Fig. 2). The results show that there was an increase on SOCS gene expression in ligature-induced periodontitis compared to control group at 7, 15 and 30 days (Fig. 4). Interestingly, the kinetics of SOCS3 expression at the mRNA level was directly correlated to the expression at the protein level. Surprisingly, for SOCS1 there was a lack of transcription–translation coupling, as mRNA levels did not correlate to protein expression. Considering the fact that RNA and protein samples were harvested simultaneously from the same wells, this may suggest the influence of post-transcriptional regulation, which has been shown to play a role for SOCS1. Alternatively, the lack of correspondence between mRNA and protein levels may merely reflect an increased efficiency of translation or a longer half-life of the protein. The mechanism of regulation of SOCS expression by periodontal disease will

be explored in future studies. Human in vivo studies suggest the involvement of SOCS1 and SOCS3 in the negative regulation Pifithrin-�� mouse of immune inflammatory networks in diseased periodontal tissues. 13 However, such data from cross-sectional studies does not allow the analysis of the kinetics of SOCS expression throughout disease onset, neither its possible association with inflammatory cell migration and with the pathological changes of the gingival tissues. In this scenario, experimental animal models of periodontitis are widely used for a better understanding of periodontal disease pathogenesis and the information derived from these models may be useful to other chronic inflammatory conditions. The ligature model of experimental periodontitis has been commonly used and considered by some authors to be more representative of periodontitis in humans ADAMTS5 than other models. The justification for this preference is the participation of live microorganisms naturally present in the animal species (in contrast

to monoinfection models with microorganisms present in humans but not in rodents) with diverse virulence factors, known as pathogen-associated molecular patterns (PAMPs), including toxins, microbial metabolism products, CpG DNA and peptidoglycan. This greater diversity of antigens may result in a more complex host response; which may have an effect on the profile of cytokine and inflammatory mediators in the gingival tissues. However, the ligature model has limited usefulness in studying natural mechanisms of infectivity since periodontal disease is facilitated by the ligature. In this study we show increased expression of SOCS1 and SOCS3, at the mRNA and protein level, in diseased gingival tissues when compared with levels in healthy gingival tissues from control animals.