Biomedical subjects
Publications and source records attributed to Hongtao Liu.
Macrophages and neutrophils are the professional phagocytes of the innate immune system. Once in the inflammatory joint or the vasculitic lesion, macrophages and neutrophils contribute to the pathology observed. This article examines the mechanisms by which phagocytes contribute to the pathogenesis of these diseases.
BACKGROUND: The availability of treatment for IgA nephropathy (IgAN) is limited. Method. A prospective randomized controlled clinical trial was performed to evaluate the effects of therapy with urokinase (UK) and benazepril (BZ, an angiotensin-converting enzyme inhibitor) or BZ alone on severe IgAN. We divided 71 cases of IgAN, Lee's grade >/=III and with fibrinogen deposits, into two groups to be treated for 12 months with either UK + BZ or BZ alone. RESULTS: There was no significant difference between the two groups in baseline clinical and histopathological data. After 12 months of treatment, 25 of 35 patients (71.4%) in the UK + BZ group and 16 of 36 (44.4%) in the BZ-alone group had a >/=50% decrease in 24-h urinary protein excretion compared with the baseline (chi(2) test, P<0.05). Proteinuria significantly decreased at 6 and 12 months of treatment in both groups compared with baseline (P<0.01 in the UK + BZ group, P<0.05 in the BZ group), and the therapeutic efficiency of UK + BZ was better than that of BZ alone (P<0.05 at 6 and 12 months). The endogenous creatinine clearance rate (Ccr) was stable in the UK + BZ group, while Ccr declined significantly at 6 and 12 months in the BZ-alone group compared with baseline (P<0.05, respectively). The Ccrs of the two groups at 12 months of treatment were statistically different (P<0.05). CONCLUSIONS: Combined therapy with UK and BZ was more effective than with BZ alone in reducing proteinuria and protecting renal function in patients with severe IgAN.
The Bcl-2 family member Mcl-1 is essential for macrophage survival. However, the mechanisms that contribute to the expression of Mcl-1 in these cells have not been fully characterized. The present study focused on the role of signal transducer and activator of transcription 3 (STAT3) in regulation of Mcl-1 in macrophages. Sodium salicylate (NaSal) treatment induced apoptotic cell death in primary human macrophages in a dose- and time-dependent fashion. Incubation with NaSal resulted in the loss of mitochondrial transmembrane potential, the release of cytochrome c and second mitochondria-derived activator of caspase/direct IAP binding protein with low pH of isoelectric point (pI) from the mitochondria, and the activation of caspases 9 and 3. Western blot analysis and reverse transcription-polymerase chain reaction demonstrated that NaSal down-regulated the expression of Mcl-1. Electrophoretic mobility shift assay and Western blot analysis for phosphorylated STAT3 demonstrated that STAT3 was constitutively activated in macrophages and that this STAT3 activation was suppressed by NaSal. The activation of STAT3 in macrophages was dependent on Ser727 phosphorylation, in the absence of detectable Tyr705 phosphorylation. Ectopic expression of STAT3 in murine RAW264.7 macrophages rescued the inhibition of Mcl-1 promoter-reporter gene activation and the cell death induced by NaSal treatment, while a dominant-negative STAT3 resulted in cell death. To confirm its role in primary macrophages, STAT3 antisense (AS) oligodeoxynucleotides (ODNs) were employed. STAT3 AS, but not control, ODNs decreased STAT3 and Mcl-1 expression and resulted in macrophage apoptosis. These observations demonstrate that the STAT3-mediated expression of Mcl-1 is essential for the survival of primary human in vitro differentiated macrophages.
During the pathogenesis of rheumatoid arthritis (RA), the synovial fibroblasts increase in number and produce proinflammatory cytokines and matrix metalloproteinases (MMPs) that function to promote inflammation and joint destruction. Recent investigations have suggested that cell cycle activity and inflammation may be linked. However, little is known about the mechanisms responsible for the coordinate regulation of proliferation and the expression of proinflammatory molecules in RA synovial fibroblasts. Here, we demonstrate a 50 +/- 10% decrease in the expression of p21, a cell cycle inhibitor, in the synovial fibroblast population from RA compared with osteoarthritis (OA) synovial tissue. Moreover, p21 positivity in the synovial fibroblasts inversely correlates with medium synovial lining thickness (r = -0.76; p < 0.02). The expression of p21 is also reduced in isolated RA synovial fibroblasts compared with OA synovial fibroblasts. Adenovirus-mediated delivery of p21 (Ad-p21) arrests both RA and OA synovial fibroblasts in the G(0)/G(1) phase of the cell cycle without inducing cytotoxicity. However, the spontaneous production of IL-6 and MMP-1 is suppressed only in the Ad-p21-infected RA synovial fibroblasts, indicating a novel role for p21 in RA. Analyses of p21-deficient mouse synovial fibroblasts reveal a 100-fold increase in IL-6 protein and enhance IL-6 and MMP-3 mRNA. Restoration of p21, but not overexpression of Rb, which also induces G(0)/G(1) cell cycle arrest, decreases IL-6 synthesis in p21-null synovial fibroblasts. Furthermore, in RA synovial fibroblasts the ectopic expression of p21 reduces activation of the AP-1 transcription factor. Additionally, p21-null synovial fibroblasts display enhanced activation of AP-1 compared with wild-type synovial fibroblasts. These data suggest that alterations in p21 expression may activate AP-1 leading to enhanced proinflammatory cytokine and MMP production and development of autoimmune disease.
OBJECTIVE: To characterize the expression pattern of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its cognate receptors (TRAIL R1, R2, R3, and R4) on rheumatoid arthritis (RA) synovial fluid (SF) lymphocytes and monocyte/macrophages and on cultured RA synovial fibroblasts. METHODS: The expression of TRAIL and TRAIL receptors on RA SF lymphocytes and monocyte/macrophages, normal macrophages, and RA synovial fibroblasts was examined by flow cytometry with previously characterized monoclonal antibodies. The ability of adenoviral-mediated delivery of TRAIL to induce macrophage or RA synovial fibroblast apoptosis was examined by flow cytometry. RESULTS: By flow cytometry, neither TRAIL nor its cognate receptors was detectable on RA SF lymphocytes or RA synovial fibroblasts. In contrast, RA SF macrophages expressed TRAIL R3, a decoy receptor (P < 0.01 versus isotype control), but not TRAIL, or TRAIL R1, R2, or R4. Normal peripheral blood-derived monocyte-differentiated macrophages expressed TRAIL R2 (P < 0.01), but not TRAIL or the other TRAIL receptors. Adenoviral-mediated delivery of TRAIL had no effect on the survival of normal macrophages or RA synovial fibroblasts but readily induced apoptosis in the prostate cancer cell line (PC-3) that expressed TRAIL R1 and R2. CONCLUSION: TRAIL R1 and R2, which are required for signal transmission by TRAIL, were not detected on RA SF lymphocytes, macrophages, or synovial fibroblasts. These observations do not support a potential therapeutic role for TRAIL in RA.
By using laser ablation on mixtures of coinage metals M (Cu, Ag, Au) and lead, M/Pb binary cluster anions containing up to tens of atoms were produced and analyzed. Most of the magic clusters discovered can be described based on the electron shell models which were deduced from simple homogeneous metal cluster systems. The clustering activities of coinage metals and lead were also compared with the properties of their bulk binary alloys.
Using a laser ablation/inert buffer gas ion source coupled with a reflectron time-of-flight mass spectrometer, the gas-phase reactions between the IVA group element ions M(+) (M = Si, Ge, Sn and Pb) and benzene seeded in argon gas were studied. In addition to the association reaction pathway (forming [M(C(6)H(6))(x)](+), x = 1, 2, etc.), benzene was dissociated to form complex ions [M(C(5)H(5))](+), [M(C(7)H(5))](+) and [M(C(9)H(x))](+) (x = 5, 7 and 9), etc. DFT theoretical calculations indicated that, in the association products [M(C(6)H(6))](+), the M atom is close to one carbon atom of benzene, while in most of the dissociation complexes, pentagonal structures (M/cyclopentadienyl derivatives) were formed, with the M atom situated near the fivefold axis of the five-membered ring. The bond patterns in these complexes are discussed.
To investigate the changes in the expression of basic fibroblast growth factor (bFGF) and transforming growth factor beta 2 (TGFbeta2) in glomus cell grafts of carotid body in the rat model of 6-hydroxydopamine-induced Parkinson disease, immunohistochemical staining of bFGF and TGFbeta2 in the sections of striate body was done on the 2nd, 4th and 12th week after transplantation. The results showed that on the 2nd week after transplantation, bFGF and TGFbeta2 were not detectable in the glumous cell grafts. On the 4th week after graft, bFGF and TGFbeta2 immunoreactivity was increased within the grafts and at the graft-host interface but was restricted only to astrocytes. In the striatum surrounding the graft, bFGF was expressed persistently, while TGFbeta2 showed transient expression. It was suggested that the transient expression of TGFbeta2 was likely due more to the trauma imposed by the graft procedure than to an intrinsic. The deficiency in astrocytic bFGF early after graft may be responsible for the poor survival of grafted glomus cells of carotid body.
Rheumatoid arthritis (RA) is a chronic inflammatory disease, which results in inflammation of the synovial lining and destruction of the adjacent bone and cartilage. Synovial macrophages, fibroblasts and lymphocytes are critical to the pathogenesis of this disease, in which apoptosis may play divergent roles. In joints of patients with active RA, few apoptotic cells are detected, and experimental data suggest that enhanced apoptosis within the joint might be therapeutically beneficial. Signaling pathways, such as the nuclear factor kappa-B, phosphatidylinositol 3-kinase/Akt-1 and signal transducer and activator of transcription-3 pathways, are highly activated in the RA joint. Activation of these pathways contributes not only to the expression of genes that cause inflammation and destruction but also to the expression of a variety of anti-apoptotic molecules, including FLICE inhibitory protein, Bcl-2, and Mcl-1, which protect against apoptosis that may be initiated through death receptor- or mitochondria-dependent pathways. The induction of apoptosis of macrophages, synovial fibroblasts or lymphocytes, either through suppression of signaling pathways or inhibition of the expression of anti-apoptotic molecules, could be therapeutically beneficial in RA. While tumour necrosis factor-alpha contributes to inflammation, destruction and protection against apoptosis in the RA joint (together with FasL), it also promotes apoptosis of bone marrow progenitor cells that contribute to anemia of chronic disease, which is very common in acute RA.
The method of recombinant PCR was employed to obtain H310D mutation in 14alpha-demethylase in Candida albicans). The expression vector pYCYPS1M harboning the mutant CYP1M gene was constructed. The mutant CYPS1 was expressed in Sacchromyces cerevisiae induced by 2% galactose. At last the MICs of yeasts to Fluconazole were determined by broth microdilution testing. Expressed protein was 15% of the total microsome proteins. The MICs of yeasts expressed the mutant CYP51 were 4-fold as that of the yeasts expressed the wild CYP51. The increase of the MICs was due to the alteration H310D in CYP51. It could be concluded that the residue of H310 was important to the function of CYPS1.
OBJECTIVE: To characterize the adenoviral properties required to enhance intracellular transgene expression for gene therapy. METHODS: Primary human fibroblasts and macrophages were infected with standard replication-defective adenoviruses, adenoviral vectors containing modified fiber coat proteins expressing Arg-Gly-Asp (RGD) or heparin sulfate binding moieties, or a tetracycline-regulatable transgene transcription system. Each of these vectors expressed the beta-galactosidase gene (beta-Gal), which was quantified by flow cytometry. Ankle joints from rats with adjuvant induced arthritis were transduced intraarticularly with each of the vectors and B-Gal expression was quantified by flow cytometry. RESULTS: Primary human fibroblasts and macrophages displayed marked increases in transgene expression from both modified fiber protein vectors and from the tetracycline-regulatable vector, compared to an unmodified vector expressing the transgene from the cytomegalovirus promoter/enhancer. In the rat model, the modified fiber protein vectors and the tetracycline-regulatable vector system also displayed increased transgene expression in inflamed rat joints. CONCLUSION: Adenovirus attachment and uptake by cells and promoter strength limit transgene expression from conventional adenoviral vectors in models of rheumatoid arthritis.