Littérature scientifique sur le sujet « LFM-A13 »

Tec kinase is an important mediator in inflammatory immune response that enhances the activity of neutrophils and macrophages. However, information on its function in lipopolysaccharide- (LPS-) induced acute kidney injury (AKI) is limited. This study is aimed at determining whether Tec kinase was a regulator in AKI. An AKI model in mice was successfully established using intraperitoneal LPS. Results showed that the serum levels of creatinine (Cr), blood urea nitrogen (BUN), and cystatin-C (Cys-C) increased after intraperitoneal LPS injection. Renal tissue sustained significantly severe injury as measured by pathological scores. Pretreatment with LFM-A13 improved the function of the kidney in mice and decreased the renal injury score. Enzyme-linked immunosorbent assay showed that LFM-A13 significantly reduced the release of IL-1β and TNF-α in mice exposed to LPS. LFM-A13 can evidently abrogate the expression of Tec protein, MyD88, TLR4, NF-κB p65, and Tec’s phosphorylated protein as determined by Western blot. Immunohistochemistry analysis revealed that LFM-A13 markedly downregulated the expression of Tec kinase in renal tubular epithelial cells. In vitro, Tec kinase protein was expressed highly in NRK-52E cells after LPS exposure. Tec-siRNA also decreased IL-1β and TNF-α production and obviously abolished phospho-p65 and phospho-IκBα expression in NRK-52E cell stimulated by LPS; however, Tec-siRNA increased the IκBα level. Altogether, these data suggested that Tec kinase can be a modulating protein in AKI through TLR4/NF-κB activation.

Abstract Abstract 884 Myeloma cells typically grow in bone, recruit osteoclast precursors and induce their differentiation and activity in areas adjacent to tumor foci. Clonal B-lymphocytes and plasma cells harboring lymphocytic phenotypes have a proposed role in sustaining myeloma. Bruton's tyrosine kinase (BTK) is expressed in hematopoietic cells and is particularly involved in B-lymphocyte function and osteoclastogenesis. The SDF-1/CXCR4 signaling pathway is reportedly involved in homing to bone of myeloma cells and osteoclast precursors. The aims of the study were to investigate the possible association between CXCR4 and BTK signaling in myeloma cells and osteoclast precursors, and the consequences of BTK inhibition on myeloma cell migration and clonogenicity, and osteoclastogenesis. By global gene expression profiling (GEP), BTK expression was moderately higher in clinical myeloma cells (n=559) than normal plasma cells (n=25, p<0.05). BTK was also detected in IL6–dependent cell lines and myeloma cell lines that can passage in vivo (n=7), using GEP, qRT-PCR and Western Blot analyses. Cell surface CXCR4 determined by flow cytometry was variably expressed in myeloma cells (5%–95%) and was significantly correlated with BTK gene expression (r=0.75, p<0.002, n=14). Most myeloma cell lines grown independently in vitro expressed very low levels of BTK; however, even in such cell lines (e.g. CAG), enrichment of myeloma cells expressing cell-surface CXCR4 by FACS analysis resulted in detectable BTK expression. BTK inhibition by shRNA in IL6–dependent INA6 cells inhibited their migration toward SDF-1 by >50% (p<0.006) and diminished their ability to form colonies in a 2-weeks clonogenic assay (p<0.0002). The BTK small molecule inhibitor LFM-A13 (25–50 μM) consistently reduced SDF-1-induced migration of primary myeloma cells and myeloma lines (n=6, p<0.03), and clonogenicity (colonies number and size) of 3 BTK-expressing myeloma lines by >50% (p<0.03). Using kinase immunoprecipitation assay, SDF-1 rapidly induced BTK phosphorylation (activation) in myeloma cells, an effect that was blocked by LFM-A13. In vivo, pretreatment of luciferase-expressing myeloma cells with LFM-A13 lessened their homing to bone following intravenous injection into SCID-rab mice as determined by live-animal imaging. BTK was highly expressed in osteoclast precursors while cell surface CXCR4 was detected in 5% of this cell population. LFM-A13 also reduced osteoclast precursor migration toward SDF-1 and suppressed osteoclast formation and bone resorption activity on dentine slices (p<0.002). In myeloma-bearing SCID-rab mice, LFM-A13 (n=10, 40 mg/kg, twice daily for 3 weeks, i.p.) reduced osteoclast number by 45% (p<0.004), prevented reduction of bone mineral density (BMD, p<0.04) and attenuated myeloma growth at near significant level (p<0.07). These data indicate that CXCR4 and BTK signaling are linked in myeloma cells and osteoclast precursors and that BTK has potential as a targeted myeloma therapy because of its roles in myeloma cell homing and clonogenicity and myeloma-induced osteolysis. Disclosures: Barlogie: Celgene, Genzyme, Novartis, Millennium: Consultancy, Honoraria, Patents & Royalties. Shaughnessy:Myeloma Health, Celgene, Genzyme, Novartis: Consultancy, Employment, Equity Ownership, Honoraria, Patents & Royalties.

Background and Purpose— Heme and iron are considered to be key factors responsible for secondary insults after intracerebral hemorrhage (ICH). Our previous study showed that LRP1 (low-density lipoprotein receptor–related protein-1)–Hx (hemopexin) facilitates removal of heme. The TLR7 (Toll-like receptor 7)–BTK (Bruton tyrosine kinase)–CRT (calreticulin) pathway regulates the expression of LRP1-Hx. This study is designed to clarify whether TLR7 activation facilitates heme scavenging and to establish the potential role of the BTK-CRT-LRP1-Hx signaling pathway in the pathophysiology of ICH. Methods— ICH was induced by stereotactic, intrastriatal injection of type VII collagenase. Mice received TLR7 agonist (imiquimod) via intraperitoneal injection after ICH induction. TLR7 inhibitor (ODN2088), BTK inhibitor (LFM-A13), and CRT agonist (thapsigargin) were given in different groups to further evaluate the underlying pathway. Mice were randomly divided into sham, ICH+vehicle (normal saline), ICH+Imiquimod (2.5, 5, and 10 μg/g), ICH+ODN2088, ICH+LFM-A13, ICH+thapsigargin, and ICH+ODN2088+thapsigargin. Imiquimod was administered twice daily starting at 6 hours after ICH; ODN2088 was administered by intracerebroventricular injection at 30 minutes, and LFM-A13 or thapsigargin was administered by intraperitoneal injection at 3 hours after ICH induction. Neurological scores, cognitive abilities, as well as brain edema, blood-brain barrier permeability, hemoglobin level, brain expression of TLR7/BTK/CRT/LRP1/Hx were analyzed. Results— Low dosage imiquimod significantly attenuated hematoma volume, brain edema, BBB permeability, and neurological deficits after ICH. Imiquimod also increased protein expressions of TLR7, BTK, CRT, LRP1, and Hx; ODN2088 reduced TLR7, BTK, CRT, LRP1, and Hx expressions. Conclusions— TLR7 plays an important role in heme scavenging after ICH by modulating the BTK-CRT-LRP1-Hx pathway. TLR7 may offer protective effects by promoting heme resolution and reduction of brain edema after ICH.

Abstract The inducible isoform of heme oxygenase (HO)-1, is involved in heme degradation producing CO and biliverdin, mediating cytoprotection against oxidative stress. Recently, HO-1 has been shown to evoke potent anti-inflammatory and immunomodulatory effects in macrophages. Here we demonstrate that Bruton's tyrosine kinase (Btk), the gene of which is mutated in human immunodeficiency X-linked agammaglobulinemia, is involved in toll-like receptor (TLR)-induced gene expression of HO-1 in macrophages. The Btk inhibitor LFM-A13 blocked the induction of HO-1 by LPS (TLR4 ligand) in RAW264.7 macrophages and primary mouse alveolar macrophages. Furthermore, LPS-stimulated up-regulation of HO-1 gene expression was abrogated in alveolar macrophages from Btk-/- mice. In addition, inhibition of Btk with LFM-A13 attenuated the LPS-induced luciferase activity of the HO-1 promoter in transfection studies in RAW264.7 cells. This effect was mediated by the transcription factor Nrf2, which is a master regulator of the cellular antioxidant defense. Immunofluorescence studies revealed that the nuclear translocation of Nrf2 in LPS-treated macrophages was reduced by Btk inhibition. Moreover, the generation of reactive oxygen species (ROS), but not that of NO, was involved in this regulatory pathway. Btk-dependent induction of HO-1 gene expression via Nrf2 was also observed upon stimulation by TLR7 and TLR9 ligands, suggesting Btk to be generally involved in TLR-mediated HO-1 gene activation.