Cardiac troponin I autoantibody induces myocardial dysfunction by PTEN signaling activation.

BACKGROUND: The objective of the current study was to study the molecular mechanism(s) underlying cardiac troponin I autoantibody (cTnIAAb) binding to cardiomyocyte and resultant myocardial damage/dysfunction. METHODS: cTnIAAb was purified from serum of 10 acute myocardial infarction (AMI) patients with left ventricular remodeling. Recombinant human cTnI was used to generate three mouse-derived monoclonal anti-cTnI antibodies (cTnImAb1, cTnImAb2, and cTnImAb3). The target proteins in cardiac myocyte membrane bound to cTnImAb and effect of cTnIAAb and cTnImAb on apoptosis and myocardial function were determined. FINDINGS: We found that cTnIAAb/cTnImAb1 directly bound to the cardiomyocyte membraneα-Enolase (ENO1) and triggered cell apoptosis via increased expression of ENO1 and Bax, decreased expression of Bcl2, subsequently activating Caspase8, Caspase 3, phosphatase and tensin homolog (PTEN) while inhibiting Akt activity. This cTnIAAb-ENO1-PTEN-Akt signaling axis contributed to increased myocardial apoptosis, myocardial collagen deposition, and impaired systolic dysfunction. INTERPRETATION: Results obtained in this study indicate that cTnIAAb is involved in the process of ventricular remodeling after myocardial injury. FUND: The National Natural Science Foundation of China (Grant#: 81260026).

HMGB1 acts in synergy with lipopolysaccharide in activating rheumatoid synovial fibroblasts via p38 MAPK and NF-κB signaling pathways.

Synovial fibroblasts (SF) play a central role in the inflammatory and destructive process in rheumatoid arthritis (RA). High-mobility group box chromosomal protein 1 (HMGB1) or lipopolysaccharide (LPS) alone failed to induce significant changes in proliferation of cultured SF from RA patients, but premixed HMGB1 with LPS (HMGB1-LPS) significantly facilitated SF proliferation. HMGB1 alone failed to induce IL-6, MMP-3, and MMP-13 production in cultured SF but greatly enhanced LPS-induced expression of IL-6, MMP-3, and MMP-13 at both mRNA and protein levels. HMGB1-LPS synergistically upregulated TLR4 and receptor for advanced glycation endproducts (RAGE) expression on the surface of SF. Both blockers of TLR4 and RAGE significantly inhibited the synergistic effects of HMGB1-LPS on the production of IL-6 and MMPs, but blocking antibodies to TLR2 failed. HMGB1-LPS synergistically increased intracellular levels of phosphorylated p38 and phosphorylated I κ B. Furthermore, both NF- κ B inhibitor Bay11-7085 and p38 inhibitor SB203580 significantly suppressed the enhanced production of IL-6 and MMPs induced by HMGB1-LPS. In conclusion, HMGB1 acts in synergy with LPS to upregulate TLR4 and RAGE expression on the surface of SF in RA and then to augment IL-6, MMP-3, and MMP-13 production, which depends on p38 MAPK and NF-κB activation.

IL-18 upregulates the production of key regulators of osteoclastogenesis from fibroblast-like synoviocytes in rheumatoid arthritis.

Recent data have demonstrated the importance of IL-18 in the induction and perpetuation of chronic inflammation in experimental arthritis. The aim of the present study was to elucidate whether IL-18 has any indirect effects on osteoclastogenesis by regulating the production of molecules from fibroblast-like synoviocytes (FLS) in rheumatoid arthritis (RA). Human FLS were isolated from RA synovial tissue and cultured in vitro for three to five passages. The expression of IL-18 receptor was determined by RT-PCR. The levels of soluble receptor activator of nuclear factor κB ligand (RANKL), osteoprotegerin (OPG), macrophage colony-stimulating factor (M-CSF), and granulocyte-macrophage colony-stimulating factor (GM-CSF) in culture supernatants were determined by ELISA. Membrane-bound RANKL expression was analyzed by flow cytometry. Both α and ß chains of IL-18 receptor were confirmed in cultured FLS. IL-18 upregulated membrane-bound RANKL expression and soluble RANKL production by FLS in both time- and dose-dependent manners. In addition, IL-18 enhanced production of M-CSF, GM-CSF, and OPG from cultured FLS in a dose-dependent manner. IL-18 also increased the ratio of RANKL/OPG, suggesting that the net effect of IL-18 on FLS favors for the induction of osteoclast formation and bone resorption. In conclusion, IL-18 upregulates the production of key regulators of osteoclastogenesis from FLS in RA.

[Increased level of Th17 cells in peripheral blood correlates with the development of hepatocellular carcinoma].

OBJECTIVE: To investigate the potential correlation between the level of Th17 cells in peripheral blood and the development of human hepatocellular carcinoma (HCC). METHODS: Th17 cells in the blood samples from 61 HCC patients and 38 healthy controls were assessed by flow cytometry (FCM). The mRNA expression levels of IL-17, IL-23p19 and RORc in peripheral blood mononuclear cells (PBMC) were detected by quantitative real-time PCR. The potential correlation of increased Th17 cells in blood with the clinical characteristics of the 61 patients, including gender, age, preoperative AFP concentration, tumor diameter, portal vein tumor thrombus (PVTT), metastasis and TNM stages was analyzed. Statistical analysis was performed using the software GraphPad Prizm 5.0. RESULTS: The number of Th17 cells in 61 HCC patients was significantly higher than that in the normal controls (4.67% ± 0.79% vs 3.25% ± 0.68%, P < 0.0001). The same tendency was also found in the mRNA levels of IL-17, IL-23p19 and RORc in PBMC (P < 0.05). The increased level of Th17 cells in HCC patients showed a positive correlation with the tumor size, PVTT, metastasis and TNM stages (P < 0.05 for each group). The level of Th17 cells in HCC patients was increased along with the increasing TNM stages I to stage IV: 4.05% ± 0.82%, 4.32% ± 0.67%, 4.94% ± 0.70%, and 5.22% ± 0.87%, respectively, where the level of Th17 cells in patients with advanced stage of HCC (III-IV) was significantly higher than that in early stage (I-II, P = 0.0008). CONCLUSION: The increased of level of Th17 cells in peripheral blood of HCC is significantly correlated with the tumor size, PVTT, metastasis and TNM stage, indicating that the Th17 cells might participate in promoting invasion and progression of HCC directly or indirectly by secreting characteristic cytokines.

HMGB1 enhances the proinflammatory activity of lipopolysaccharide by promoting the phosphorylation of MAPK p38 through receptor for advanced glycation end products.

High mobility group box-1 (HMGB1) protein was originally characterized as a nuclear DNA-binding protein, and was described to have an extracellular role when involved in cellular activation and proinflammatory responses. In the present study, we have found that the proinflammatory activity of recombinant HMGB1 proteins is determined by the containing endotoxin level, and HMGB1 that contains few endotoxins fails to stimulate macrophages to secrete proinflammatory cytokines. HMGB1 acts as a ligand of receptor for advanced glycation end products (RAGE) and works in synergy with LPS in activating the macrophages in vitro. In vivo, intra-articular injections of HMGB1 act in synergy with LPS to induce experimental arthritis in mice. HMGB1 promotes the phosphorylation of MAPK p38 and the activation of NF-kappaB through RAGE, and then enhances the expression of proinflammatory cytokines. These results demonstrate that HMGB1 enhances the proinflammatory activity of LPS by promoting the phosphorylation of MAPK p38 and by the activation of NF-kappaB through RAGE.