SPOCK1 induces adipose tissue maturation: New insights into the function of SPOCK1 in metabolism.

SPOCK1 is a calcium-binding matricellular proteoglycan that has been extensively studied in several cancer cells. Previously, we generated a mouse line overexpressing SPOCK1 (Spock1-Tg mouse) and showed that SPOCK1 might play an important role in drug-induced gingival overgrowth, indicating that it possesses physiological functions in non-cancer diseases as well. Although SPOCK1 was reported to be secreted from human adipocytes, its role in adipocyte physiology has not been addressed yet. In this study, SPOCK1 protein expression was confirmed in pancreas, adipose tissues, spleen, and liver of normal diet (ND)-fed mice. Interestingly, SPOCK1 was up-regulated in the pancreas and adipose tissues of the high-fat diet (HFD)-fed mice. Spock1-Tg mice fed with ND showed increased maturation in epididymal and inguinal adipose tissues. In addition, Spock1 overexpression strongly decreased expression of UCP-1 in adipose tissues, suggesting that SPOCK1 might regulate thermogenic function through suppression of UCP-1 expression. Finally, exogenous SPOCK1 treatment directly accelerated the differentiation of 3T3-L1 adipocytes, accompanied by the up-regulation of adipocyte differentiation-related gene expression. In conclusion, we demonstrated for the first time that SPOCK1 induced adipocyte differentiation via the up-regulation of adipogenesis-related genes.

Anti-inflammatory effects of miRNA-146a induced in adipose and periodontal tissues.

MicroRNA (miRNA) plays an important role in diverse cellular biological processes such as inflammatory response, differentiation and proliferation, and carcinogenesis. miR-146a has been suggested as a negative regulator of the inflammatory reaction. Although, it has been reported as expressed in inflamed adipose and periodontal tissues, however, miR-146a's inhibitory effects against inflammatory response in both the tissues, are not well understood. Therefore, in this study, the inhibitory effects of miR-146a on both adipose and periodontal inflammation, was investigated. In vitro study has revealed that miR-146a transfection into either adipocytes or gingival fibroblasts, has resulted in a reduced cytokine gene expression, observed on co-culturing the cells with macrophages in the presence of lipopolysaccharides (LPS), in comparison to the control miRNA transfected. Similarly, miR-146a transfection into macrophages resulted in a reduced expression of TNF-α gene and protein in response to LPS stimulation. In vivo study revealed that a continuous intravenous miR-146a administration into mice via tail vein, protected the mice from developing high-fat diet-induced obesity and the inflammatory cytokine gene expression was down-regulated in both adipose and periodontal tissues. miR-146a appeared to be induced by macrophage-derived inflammatory signals such as TNF-α by negative feed-back mechanism, and it suppressed inflammatory reaction in both adipose and periodontal tissues. Therefore, miR-146a could be suggested as a potential therapeutic molecule and as a common inflammatory regulator for both obesity-induced diabetes and related periodontal diseases.

Amelogenin Downregulates Interferon Gamma-Induced Major Histocompatibility Complex Class II Expression Through Suppression of Euchromatin Formation in the Class II Transactivator Promoter IV Region in Macrophages.

Enamel matrix derivatives (EMDs)-based periodontal tissue regenerative therapy is known to promote healing with minimal inflammatory response after periodontal surgery, i. e., it promotes wound healing with reduced pain and swelling. It has also been reported that macrophages stimulated with amelogenin, a major component of EMD, produce various anti-inflammatory cytokines and growth factors. We previously found that stimulation of monocytes with murine recombinant M180 (rM180) amelogenin suppresses major histocompatibility complex class II (MHC II) gene expression using microarray analysis. However, the detailed molecular mechanisms for this process remain unclear. In the present study, we demonstrated that rM180 amelogenin selectively downmodulates the interferon gamma (IFNγ)-induced cell surface expression of MHC II molecules in macrophages and this mechanism mediated by rM180 appeared to be widely conserved across species. Furthermore, rM180 accumulated in the nucleus of macrophages at 15 min after stimulation and inhibited the protein expression of class II transactivator (CIITA) which controls the transcription of MHC II by IFNγ. In addition, reduced MHC II expression on macrophages pretreated with rM180 impaired the expression of T cell activation markers CD25 and CD69, T cell proliferation ability, and IL-2 production by allogenic CD4+ T lymphocytes in mixed lymphocyte reaction assay. The chromatin immunoprecipitation assay showed that IFNγ stimulation increased the acetylation of histone H3 lysine 27, which is important for conversion to euchromatin, as well as the trimethylation of histone H3 lysine 4 levels in the CIITA promoter IV (p-IV) region, but both were suppressed in the group stimulated with IFNγ after rM180 treatment. In conclusion, the present study shows that amelogenin suppresses MHC II expression by altering chromatin structure and inhibiting CIITA p-IV transcription activity, and attenuates subsequent T cell activation. Clinically observed acceleration of wound healing after periodontal surgery by amelogenin may be partially mediated by the mechanism elucidated in this study. In addition, the use of recombinant amelogenin is safe because it is biologically derived protein. Therefore, amelogenin may also be used in future as an immunosuppressant with minimal side effects for organ transplantation or MHC II-linked autoimmune diseases such as type I diabetes, multiple sclerosis, and rheumatoid arthritis, among others.

SPOCK1 is a novel inducer of epithelial to mesenchymal transition in drug-induced gingival overgrowth.

Few studies have investigated the role of extracellular-matrix proteoglycans in the pathogenesis of drug-induced gingival overgrowth (DIGO). SPOCK1 is an extracellular proteoglycan that induces epithelial to mesenchymal transition (EMT) in several cancer cell lines and exhibits protease-inhibitory activity. However, the role of SPOCK1 in non-cancerous diseases such as DIGO has not been well-addressed. We demonstrated that the expression of SPOCK1, TGF-ß1, and MMP-9 in calcium channel blocker-induced gingival overgrowth is higher than that in non-overgrowth tissues. Transgenic mice overexpressing Spock1 developed obvious gingival-overgrowth and fibrosis phenotypes, and positively correlated with EMT-like changes. Furthermore, in vitro data indicated a tri-directional interaction between SPOCK1, TGF-ß1, and MMP-9 that led to gingival overgrowth. Our study shows that SPOCK1 up-regulation in a noncancerous disease and SPOCK1-induced EMT in gingival overgrowth occurs via cooperation and crosstalk between several potential signaling pathways. Therefore, SPOCK1 is a novel therapeutic target for gingival overgrowth and its expression is a potential risk of EMT induction in cancerous lesions.

Adhesion attenuates respiratory burst induced by different modes of triggering in resting or LPS-primed neutrophils.

The effects of adherence on neutrophil superoxide anion (O2-) generation triggered by surface, soluble ligand, or adherence were studied. Resting-neutrophils adhered to the uncoated tubes resulting in O2- generation, but not on plasma-, fibrinogen-, vitronectin-, fibronectin-, laminin-, collagen-, or poly HEMA-coated surfaces. Enhanced N-formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated O2- generation by LPS-primed-neutrophils was induced by the incubation on plasma, fibrinogen, vitronectin, fibronectin, or laminin in the absence of Mg2+. In the presence of Mg2+, this response was observed in cells on collagen or poly HEMA. LPS-primed-neutrophils adhered to uncoated, BSA- or IgG-coated tubes and did not respond to fMLP, indicating that the fMLP-response of LPS-primed-neutrophils was suppressed by adherence. Upon incubation on plasma, fibrinogen, vitronectin, fibronectin in the presence of Mg2+, LPS-primed-neutrophils showed O2- generation. Upon incubation on collagen or poly HEMA, the primed-neutrophils neither generated O2- nor adhered. We found that O2- response of LPS-primed-neutrophils was attenuated depending on the time of exposure to plasma-coated surface. This attenuation was evident on plasma or fibrinogen, but not on collagen in the presence of Mg2+, indicating that O2- generation by LPS-primed-neutrophils was attenuated dependent on adherence but not on Mg2+. Thus, adhesion attenuated the O2- generation triggered by both soluble (fMLP) and insoluble (surface) stimuli.

Roles of serum in innate immune responses of human leukocytes to synthetic lipopeptide.

Tripalmitoyl-S-glyceryl-l-Cys-Ser-(Lys)4 (Pam3CSK4) is a highly conserved molecular motif found in various classes of lipoproteins. The requirement for leukocyte to respond to synthetic Pam3CSK4 were studied. Pam3CSK4 primed neutrophils for a respiratory burst in a serum-dependent manner. Pam3CSK4 upregulated CD11b, CD14, and cytochrome b558, and downregulated Leu-8. Treatment of neutrophils with anti-CD14 antibodies and treatment of serum with anti-LPS binding protein (LBP) antibodies resulted in the inhibition of priming for respiratory burst by Pam3CSK4. It should be noted that LBP could not replicate the effects of serum in priming of neutrophils for respiratory burst by Pam3CSK4. Serum LBP bound to immobilized Pam3CSK4. Pam3CSK4 induced the interleukin-8 (IL-8) production by leukocytes in a serum-dependent manner. Further, Pam3CSK4-induced priming of neutrophils for respiratory burst was not inhibited by the LPS antagonists LA-14-PP, Rhodobacter sphaeroides LPS, or E5531, and Pam3CSK4-induced IL-8 production by leukocytes was not affected by LPS antagonist, E5531, indicating that Pam3CSK4 was recognized by a different receptor than LPS. Thus, Pam3CSK4 and LPS had similar biological activities and similar requirement to act on leukocytes, but were recognized by different receptors. Serum in the action of Pam3CSK4 on leukocytes was not replicated by LBP, suggesting that Pam3CSK4 might be disaggregated by serum to result in the activation of leukocytes.