Deficiency of ß-arrestin2 exacerbates inflammatory arthritis by facilitating plasma cell formation.

ß-arrestin2 (ß-arr2) is, a key protein that mediates desensitization and internalization of G protein-coupled receptors and participates in inflammatory and immune responses. Deficiency of ß-arr2 has been found to exacerbate collagen antibody-induced arthritis (CAIA) through unclear mechanisms. In this study we tried to elucidate the molecular mechanisms underlying ß-arr2 depletion-induced exacerbation of CAIA. CAIA was induced in ß-arr2-/- and wild-type (WT) mice by injection of collagen antibodies and LPS. The mice were sacrificed on d 13 after the injection, spleen, thymus and left ankle joints were collected for analysis. Arthritis index (AI) was evaluated every day or every 2 days. We showed that ß-arr2-/- mice with CAIA had a further increase in the percentage of plasma cells in spleen as compared with WT mice with CAIA, which was in accordance with elevated serum IgG1 and IgG2A expression and aggravating clinical performances, pathologic changes in joints and spleen, joint effusion, and joint blood flow. Both LPS stimulation of isolated B lymphocytes in vitro and TNP-LPS challenge in vivo led to significantly higher plasma cell formation and antibodies production in ß-arr2-/- mice as compared with WT mice. LPS treatment induced membrane distribution of toll-like receptor 4 (TLR4) on B lymphocytes, accordingly promoted the nuclear translocation of NF-κB and the transcription of Blimp1. Immunofluorescence analysis confirmed that more TLR4 colocalized with ß-arr2 in B lymphocytes in response to LPS stimulation. Depletion of ß-arr2 restrained TLR4 on B lymphocyte membrane after LPS treatment and further enhanced downstream NF-κB signaling leading to additional increment in plasma cell formation. In summary, ß-arr2 depletion exacerbates CAIA and further increases plasma cell differentiation and antibody production through inhibiting TLR4 endocytosis and aggravating NF-κB signaling.

Prednisone treatment inhibits the differentiation of B lymphocytes into plasma cells in MRL/MpSlac-lpr mice.

AIM: A number of evidence shows that the differentiation of B lymphocytes into plasma cells plays an important role in lupus pathogenesis. In this study we investigated how prednisone, a classical therapeutic drug for autoimmune diseases, regulated plasma cell differentiation in MRL/MpSlac-lpr mice. METHODS: MRL/lpr mice were treated with prednisone (2.5 or 5 mg·kg(-1)·d(-1), ig) for 13 weeks, and the proteinuria levels and survival times were monitored. After the mice were euthanized, blood sample, spleen and thymus were collected. The serum levels of anti-dsDNA antibody, anti-nuclear antibody, IL-21, and IL-10 were detected using ELISA kits. Subsets of splenic B and T lymphocytes were quantified with flow cytometry. Transcription factor Blimp-1 and Bcl-6 expression was determined using qPCR and Western blot. RESULTS: Prednisone treatment dose-dependently attenuated the lupus symptoms in MRL/lpr mice with decreased proteinuria levels, prolonged survival times, decreased serum anti-nuclear antibody levels, and reduced spleen and thymus indices. Prednisone treatment also significantly decreased the elevated percentages of plasma cells and plasma cell precursors, decreased the percentages of activated T cells, and increased the frequency of CD4(+)CD62L(+) cells, demonstrated that decreased anti-nuclear antibodies and improvements in lupus symptoms were associated with decreased plasma cells. Furthermore, prednisone treatment decreased serum IL-21 and IL-10 levels and reduced the expression of splenic Blimp-1 and Bcl-6 (two key regulatory factors for plasma cell differentiation) in MRL/lpr mice. CONCLUSION: Prednisone treatment restricts B lymphocyte differentiation into plasma cells in MRL/lpr mice, which may be correlated with the inhibition of IL-21 production and the restoration of the balance between Blimp-1 and Bcl-6.

Angiotensin II and tumor necrosis factor-α stimulate the growth, migration and invasion of BEL-7402 cells via down-regulation of GRK2 expression.

PURPOSE: To investigate the effects of angiotensin II (Ang II) and tumor necrosis factor-α (TNF-α) on the biological characteristics of hepatocellular carcinoma (HCC) cells and the associated changes in G protein-coupled receptor kinase 2 (GRK2) expression. METHODS: The mean serum levels of Ang II and TNF-α in normal subjects and patients with benign liver tumors (BLTs) and HCC were evaluated by enzyme-linked immunosorbent assay (ELISA), and liver samples from the patients with HCC and HCC mice were used to assess the protein levels of both cytokines, their major receptors and GRK2. In addition, the dynamics of Bel-7402 cells were determined with cell counting kit-8 (CCK-8) and Transwell experiments, while the levels of the primary cytokine receptors Ang II type-1 receptor (AT1R) and type-2 receptor (AT2R) as well as TNF receptor 1 (TNFR1) were detected by flow cytometry (FCM). The effects of Ang II and TNF-α on the GRK2 levels in Bel-7402 cells and on the dynamics of GRK2-knockdown HCC cells were also investigated. RESULTS: Both cytokines independently enhanced Bel-7402 cell growth, migration and invasion by decreasing the GRK2 level. In contrast, down-regulating the GRK2 level in Bel-7402 cells suppressed these effects. No synergistic effects were discovered when Ang II and TNF-α were administered together. Furthermore, increased AT1R and TNFR1 levels stimulated HCC initiation and progression, whereas AT2R overexpression produced the opposite effect. CONCLUSIONS: The present results suggested that Ang II and TNF-α promote Bel-7402 cell growth, migration and invasion by down-regulating GRK2 expression, and that the associated receptors AT1R, AT2R and TNFR1 participate in HCC initiation and progression.

[Pulmonary immune responses to acute lung injury following smoke inhalation and its mechanisms].

OBJECTIVE: To analyze pulmonary innate and specific immune responses following the smoke inhalation-induced acute lung injury (ALI). METHODS: Smoke inhalation-induced ALI should be replicated at high (4x10(-3)) and low (2x10(-3)) dose of carbon monoxide (CO) respectively for 24 hours. After this period, lung tissue histopathological changes and the parameters of both treatment groups were observed compared to those of control animals: the phasic variations of concentrations of pro-anti-inflammatory cytokines in bronchoalveolar lavage fluid (BALF), numbers of lymphocyte subsets in peripheral blood and BALF, CD45(+) lymphoid leukocytes, CD45(+) nonlymphoid leukocytes and CD4(+)/CD8(+) in BALF were determined by flow cytometry (FCM). RESULTS: Lung histopathological changes of smoke-exposed animals revealed obvious alveolar leakage characterizing ALI. Concentrations of tumor necrosis factor-alpha (TNF-alpha) in BALF were increased immediately after injury and reached the peak at 2 hours after injury, and more obvious changes were seen in high dose group than those in low dose group. Levels of interleukin-6 (IL-6) and interferon-gamma (IFN-gamma) were elevated following after 4 hours injury peaking at 12 hours. The changes of levels of IL-6 in low dose group were more obviously than those in high dose group, and those of IFN-gamma were reverse. Levels of IL-6 and IFN-gamma were decreased at 24 hours, still higher than those of control group (P<0.05 or P<0.01), whereas the expressions of IL-10 were increased at 6 hours, and continuing upregulation to 24 hours compared with those of control group (P<0.05 or P<0.01). Additionally, the numbers of lung-resident CD4(+) T cells, CD8(+) T cells, natural killer cells, B cells and total T-lymphocytes in peripheral blood and BALF were significantly reduced after challenge (P<0.05 or P<0.01). The number of CD45(+) lymphoid leukocytes in BALF and CD4(+)/CD8(+) were decreased; while that of CD45(+) nonlymphoid leukocytes was increased obviously compared with those of control group, and obviously changed in high dose group than in low dose group (P<0.05 or P<0.01). CONCLUSION: These data suggest that smoke inhalation induced ALI is associated with exaggerated and sustained pulmonary innate immune responses partly by activated polymorphonuclear neutrophils (PMN) and macrophage, whereas specific immunity in the lung is suppressed obviously.

The influence of TNF-α and Ang II on the proliferation, migration and invasion of HepG2 cells by regulating the expression of GRK2.

PURPOSE: Hepatocellular carcinoma (HCC) is a common digestive system malignancy that is associated with a poor prognosis. This study researched the interaction of tumor necrosis factor-α (TNF-α) and angiotensin II (Ang II) in HCC cells proliferation, migration and invasion and examined their influence on the expression of G protein-coupled receptor kinase 2 (GRK2) and relevant receptors. METHODS: Cell Counting Kit-8 and Transwell assays were performed to evaluate the effects of TNF-α and Ang II on HepG2 cells proliferation, migration and invasion. Flow cytometry was used to investigate the expression of tumor necrosis factor receptor 1 (TNFR1), angiotensin II type 1 (AT1R) and type 2 receptors (AT2R) on the surface of HepG2 cells. Additionally, Western blot was performed to assess the modulation of GRK2 expression by TNF-α and Ang II in HepG2 cells. Meanwhile, GRK2 siRNA-transfected HepG2 cells were used to confirm the effects of GRK2, TNF-α and Ang II on the proliferation, migration and invasion of GRK2-knockdown HCC cells. Finally, the expression of TNF-α, Ang II, TNFR1, AT1R, AT2R and GRK2 proteins in HCC, tumor-adjacent and normal liver tissues were tested by immunohistochemistry. RESULTS: The data demonstrated that TNF-α and Ang II can enhance the proliferation, migration and invasion of HepG2 cells through suppressing GRK2 expression but that the two reagents combined did not have synergistic effects. Moreover,overexpression of TNFR1 and AT1R perhaps promoted the formation and progression of HCC, while high AT2R expression had the opposite effect. CONCLUSIONS: This study provides new ideas for the prevention and treatment of HCC by researching the interaction and probable mechanism of different bioactive factors associated with HCC.

Effects of total glucosides of peony on immunological hepatic fibrosis in rats.

AIM: To study the effects of total glucosides of peony (TGP) on immunological hepatic fibrosis induced by human albumin in rats. METHODS: Sixty adult male Sprague-Dawley rats were randomly divided into: Normal group, model group, TGP (60 and 120 mg/kg) treatment groups and colchicines (0.1 mg/kg) treatment group. On the day before the rats were killed, those in TGP or colchicine groups received TGP or colchicine as above from the first day of tail vein injection of human albumin. The rats in normal and model groups were only administered with the same volume of vehicle. At the end of the 16th wk, rats in each group were killed. Blood and tissue specimens were taken. Levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), nitric oxide (NO), content of malondialdehyde (MDA), activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-px), were measured by biochemical methods. Serum procollagen type III (PC III) and laminin (LN) were determined by radioimmunoassay. Liver collagen level was determined by measuring hydroxyproline content in fresh liver samples. Hepatic tissue sections were stained with hematoxylin-eosin and examined under a light microscope. RESULTS: Histological results showed that TGP improved the human albumin-induced alterations in the liver structure, alleviated lobular necrosis and significantly lowered collagen content. The antifibrotic effect of TGP was also confirmed by decreased serum content of LN and PCIII in TGP-treated group. Moreover, the treatment with TGP effectively reduced the hydroxyproline content in liver homogenates. However, the level of ALT and AST increased in fibrotic rat but had no significance compared with normal control, whereas the ratio of A/G decreased without significance. TGP had no effect on level of ALT, AST and the ratio of A/G. Furthermore, TGP treatment significantly blocked the increase in MDA and NO, associated with a partial elevation in liver total antioxidant capacity including SOD and GSH-px. CONCLUSION: TGP has beneficial effects on hepatic fibrosis in rats by inhibition of collagen synthesis and decreasing oxidative stress.

IL-21 acts as a promising therapeutic target in systemic lupus erythematosus by regulating plasma cell differentiation.

Plasma cells, which secrete auto-antibodies, are considered to be the arch-criminal of autoimmune diseases such as systemic lupus erythematosus, but there are many cytokines involved in inducing the differentiation of B-cell subsets into plasma cells. Here, we emphasize IL-21, which has emerged as the most potent inducer of plasma cell differentiation. In this review, we focused on the promoting effects of IL-21 on plasma cell differentiation and discuss how these effects contribute to B cell-mediated autoimmune disease.

Therapeutic effects of glucosides of Cheanomeles speciosa on collagen-induced arthritis in mice.

AIM: To investigate the therapeutic effect of the glucosides of Cheanomeles speciosa (GCS) on the collagen-induced arthritis (CIA) in mice. METHODS: Mice were divided randomly into six groups, including normal, CIA, CIA+GCS (60, 120, and 240 mg/kg) and CIA plus glucosides of Tripterygium wilfordii (GTW) groups. CIA model was based on mice. The effect of GCS in CIA mice was measured by paw-swelling, arthritis scores, and histopathological assessment of synovium. Indices of thymus and spleens were measured. Thymocytes and splenocytes proliferation, activity of interleukin-1 (IL-1), and interleukin-2 (IL-2) were assayed by MTT and [(3)H]TdR method. The level of anti-collagen type II (CII) antibody in serum and prostaglandin E (PGE) in ankle were assayed by ELISA and ultraviolet spectrophotometer method, respectively. RESULTS: The onset of paw-swelling was on d 24 after injection of emulsion. The peak of secondary inflammation appeared on d 36 and then declined after d 40. GCS and GTW significantly reduced paw-swelling and arthritis scores, reduced the increase of spleen indices of CIA mice, suppressed the ConA or LPS-induced thymocyte or spleen cell proliferation, and the production of IL-1 and IL-2 in CIA mice. GCS reduced the level of anti-CII antibody and PGE. Histological pathology analysis demonstrated that the synovium of CIA mice was hyperplastic, pannus was formed, and inflammatory cells infiltrated into synovium. The pathological changes were significantly reduced by GCS. CONCLUSION: GCS had anti-inflammatory effect on CIA mice, which might be related to the modification of the abnormal immunological function of CIA mice.