Adipokine Chemerin Bridges Metabolic Dyslipidemia and Alveolar Bone Loss in Mice

Chemerin is an adipokine that regulates adipogenesis and metabolic functions of mature adipocytes mainly through the activation of chemokine‐like receptor 1 (CMKLR1). Elevated levels of chemerin have been found in individuals with obesity, type 2 diabetes, and osteoporosis. This adipokine was identified as an inflammatory and metabolic syndrome marker. Considering that the association between metabolic syndrome and bone health remains unclear, the present study aimed to clarify the role of chemerin in the pathophysiology of bone loss induced by dyslipidemia, particularly modulating osteoclastogenesis. In vitro analyses showed a downregulation of CMKLR1 at the early stage of differentiation and a gradual increase at late stages. Strikingly, chemerin did not modify osteoclast differentiation markers or osteoclast formation; however, it increased the actin‐ring formation and bone resorption activity in mature osteoclasts. The increased bone resorption activity induced by chemerin was effectively inhibited by CMKLR1 antagonist (CCX832). Chemerin boosting mature osteoclast activity involves ERK5 phosphorylation. Moreover, two models of dyslipidemia (high‐fat diet [HFD]‐treated C57/BL6 and db/db mice) exhibited significantly increased level of chemerin in the serum and gingival tissue. Morphometric analysis showed that HFD‐treated and db/db mice exhibited increased alveolar bone loss compared to respective control mice, which was associated with an up‐regulation of chemerin, CMKLR1 and cathepsin K mRNA expression in the gingival tissue. The treatment of db/db mice with CCX832 effectively inhibited bone loss. Antagonism of chemerin receptor also inhibited the expression of cathepsin K in the gingival tissue. Our results show that chemerin not only increases osteoclasts activity in vitro, but also that increased level of chemerin in dyslipidemic mice plays a critical role in bone homeostasis. © 2016 American Society for Bone and Mineral Research.     

Ceftriaxone Blocks the Polymerization of α-Synuclein and Exerts Neuroprotective Effects in Vitro

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Renal and hematologic side effects of long‐term intravenous immunoglobulin therapy in patients with neurologic disorders

Introduction: For patients receiving intravenous immunoglobulin (IVIg), renal and hemolytic side effects are well recognized. However, there are very few data on the effects of chronic IVIg therapy. Methods: We retrospectively analyzed laboratory data on 166 patients who received IVIg for 12 months with a dose range of 0.441–2.58 g/kg/month, measuring changes in hematocrit and glomerular filtration (GFR) rates at 6 and 12 months. Results: Of the 2,232 infusions, there were no incidents of clinical hemolysis. However, after 12 months of treatment, 21% of patients had a ≥3‐g/dl decline in hematocrit and 10% had a ≥20% decline in GFR. Discussion: No clinically significant hemolysis was observed in patients receiving chronic IVIg therapy. However, a significant number of patients had a decline in hematocrit and/or GFR while on therapy. This emphasizes the need for observation of hematologic and renal function in patients treated with chronic IVIg. Muscle Nerve 56 : 1173–1176, 2017     

Priming of human neutrophils with N-formyl-methionyl-leucyl- phenylalanine by a calcium-independent, pertussis toxin-insensitive pathway

Resting neutrophils may be "primed" to augmented effector function, eg, superoxide (O2-) production in the respiratory burst, upon a second stimulation with a variety of soluble agonists including formylated methionyl-leucyl-phenylalanine (FMLP) and phorbol myristate acetate (PMA). At priming concentrations of FMLP (5 x 10(-9) mol/L) that did not initiate O2- generation, two metabolic activities were noted: (1) approximately a threefold increase in the baseline intracellular calcium (Ca++i) level, that was not dependent on extracellular Ca++, and (2) a rapid rise in intracellular pH that was blocked by 5-(N,N- dimethyl) amiloride (DA), that had no effect on the Ca++i response to priming. Furthermore, there were no significant increases in inositol metabolites in cells primed and stimulated with FMLP compared with cells receiving the stimulating dose of FMLP alone and pretreatment with pertussis toxin (PT) (before the addition of the priming -5 x 10(- 9) mol/L dose of FMLP), whereas abolishing the response to FMLP during the second stage of stimulation, had (1) no effect on FMLP-primed cells subsequently stimulated with PMA, and (2) only partially ablated the rise in Ca++i initiated with FMLP. That FMLP priming involved distinctive processes to those of the well characterized FMLP-coupled Ca++-dependent activation cascade was shown by the full priming effect attained in a Ca++-free buffer, which did not sustain an O2- response to a second-stage FMLP stimulation, but sustained a primed response to PMA. These data demonstrate that FMLP primes human neutrophils by a Ca++-independent and PT-insensitive pathway, offering a functional model for studying heterogeneous FMLP receptor-coupled reactions.     

Association of granulocyte-macrophage colony-stimulating factor with the crystalloid granules of human eosinophils

We have previously shown that normal-density human peripheral blood eosinophils transcribe and translate mRNA for granulocyte-macrophage colony-stimulating factor (GM-CSF) and that the intracellular distribution was granular as assessed by light microscopy immunocytochemistry. The present study was conducted to confirm this apparent association between GM-CSF and the crystalloid granule using a subcellular fractionation method for human eosinophils and immunogold electron microscopy (EM). Highly purified (> 99%, by negative selection using anti-CD16 immunomagnetic microbeads) human peripheral blood eosinophils were obtained from four asthmatic subjects (not taking systemic medication), homogenized and density fractionated (5 x 10(7) cells/subject) on linear Nycodenz gradients. Twenty-four fractions were collected from each cell preparation and analyzed for marker enzyme activities as well as total protein. Dot blot analysis with specific monoclonal antibodies (MoAbs) was used to detect the eosinophil granule proteins major basic protein (MBP) and eosinophil cationic protein (ECP). An anti-CD9 MoAb was used as an eosinophil plasma membrane marker. Lactate dehydrogenase (LDH) was used as a cytosolic marker. Immunoreactivity for GM-CSF was detected by a specific enzyme-linked immunosorbent assay using a polyclonal antihuman GM-CSF antibody and confirmed by dot blot. GM-CSF coeluted with the cellular fractions containing granule markers (MBP, ECP, eosinophil peroxidase, hexosaminidase, and arylsulphatase), but not those containing cytoplasm (LDH+) or membrane (CD9+) markers. EM examination of pooled fractions associated with the peak of GM-CSF immunoreactivity confirmed that they contained crystalloid and small granules, but not plasma membrane. In addition, quantification, using immunogold labeling with an anti/GM-CSF MoAb, indicated preferential localization of gold particles over the eosinophil granule cores of intact cells. Thus, our results indicate that GM-CSF resides as a granule-associated, stored mediator in unstimulated human eosinophils.     

Mitochondrial perturbations and oxidant stress in lymphocytes from patients undergoing surgery and general anesthesia

BACKGROUND: Previous studies have shown that a profound suppression of immune function transiently occurs in patients who undergo surgery under general anesthesia. The decline in the absolute counts of peripheral blood lymphocytes constitutes a major factor accounting for this immune defect, and recent evidence indicates that apoptosis plays a crucial role in determining postsurgical lymphocytopenia. HYPOTHESIS: An altered oxidation-reduction status of mitochondria may contribute through apoptosis to the loss of lymphocytes following surgical trauma and general anesthesia. DESIGN: We studied 16 patients with American Society of Anesthesiologists' physical status I or II who underwent elective surgery under general anesthesia. The data were collected prospectively. SETTING: University hospital. MAIN OUTCOME MEASURES: Samples of peripheral blood were drawn on the day before surgery and at 24 and 96 hours after the operation. Following lymphocyte isolation, the mitochondrial transmembrane potential was assessed by flow cytometry using 3,3'-dihexylocarbo-cyanine iodide, and stains with hydroethidine and 2'-7'-dichlorofluorescein diacetate were used to determine the generation of reactive oxygen species. The labeling of lymphocytes with monobromobimane was used to assess the presence of reduced glutathione. RESULTS: At 24 hours after surgery, we detected a significantly elevated frequency of peripheral blood lymphocytes (P =.002), which incorporated low levels of 3,3'-dihexylocarbo-cyanine iodide, compared with the preoperative period. At this same time point, the frequency of lymphocytes with the hydroethidine- and 2'-7'-dichlorofluorescein diacetate-positive phenotype was elevated compared with baseline levels. Conversely, at 24 hours after surgery, the frequency of cells that stained positive for glutathione was strongly decreased compared with preoperative values. Overall measurements returned to the baseline levels at 96 hours after surgery. CONCLUSION: The strict association we observed between the overproduction of reactive oxygen species and the disruption of the mitochondrial transmembrane potential supports the view that alterations in mitochondrial energy metabolism, paralleled by the presence of a pro-oxidant oxidation-reduction status, could be involved in the accelerated apoptotic loss of lymphocytes following surgical trauma and general anesthesia.