Chemerin regulates ß-cell function in mice.

Although various function of chemerin have been suggested, its physiological role remains to be elucidated. Here we show that chemerin-deficient mice are glucose intolerant irrespective of exhibiting reduced macrophage accumulation in adipose tissue. The glucose intolerance was mainly due to increased hepatic glucose production and impaired insulin secretion. Chemerin and its receptor ChemR23 were expressed in ß-cell. Studies using isolated islets and perfused pancreas revealed impaired glucose-dependent insulin secretion (GSIS) in chemerin-deficient mice. Conversely, chemerin transgenic mice revealed enhanced GSIS and improved glucose tolerance. Expression of MafA, a pivotal transcriptional factor for ß-cell function, was downregulated in chemerin-deficient islets and a chemerin-ablated ß-cell line and rescue of MafA expression restored GSIS, indicating that chemerin regulates ß-cell function via maintaining MafA expression. These results indicate that chemerin regulates ß-cell function and plays an important role in glucose homeostasis in a tissue-dependent manner.

Chemerin peptides promote phagocytosis in a ChemR23- and Syk-dependent manner.

Chemerin peptides represent a recently identified component of the endogenous anti-inflammatory network that act via the G protein-coupled receptor ChemR23. The role of the chemerin peptide/ChemR23 pathway in phagocytosis, the clearance of apoptotic cells (efferocytosis), and the resolution of inflammation is unknown. In this article, we report that low picomolar concentrations of the chemerin peptide chemerin15 (C15) enhance macrophage (MPhi) phagocytosis of microbial particles and apoptotic cells by up to 360% in vitro. These prophagocytic effects of C15 are significantly impaired in ChemR23(-/-) MPhis and are associated with increased actin polymerization and localization of F-actin to the phagocytic cup. Importantly, pharmacological inhibition of Syk activity completely abrogates the prophagocytic activities of C15 and associated changes in actin polymerization and phagocytic cup formation, suggesting that C15 promotes phagocytosis by facilitating phagocytic cup development in a Syk-dependent manner. During peritoneal inflammation, C15 administration (8 pg/mouse) enhances microbial particle clearance and apoptotic neutrophil ingestion by MPhis in wild-type but not ChemR23(-/-) mice, such that levels of apoptotic and necrotic cells at the inflammatory site are profoundly reduced. In contrast, neutralization of endogenous chemerin species during peritoneal inflammation significantly impairs MPhi ingestion of apoptotic neutrophils and zymosan. Our data identify a key role of the chemerin peptide/ChemR23 axis in the efficient clearance of foreign material, efferocytosis, and, hence, the resolution of inflammation. Manipulation of the chemerin peptide/ChemR23 axis may represent a novel therapeutic approach for the treatment of inflammatory pathologies, especially if failure to efficiently clear phagocytic targets has been implicated in their pathogenesis.

Promoter hyper-methylation of calcium binding proteins S100A6 and S100A2 in human prostate cancer.

BACKGROUND: S100A6 and S100A2 are members of the S100 family of calcium binding proteins, which are down regulated in prostate cancer, however the molecular mechanism(s) underlying their loss of expression is unknown. METHODS: The promoter and exon 1 region of the S100A6 and S100A2 genes was sequenced in bisulfite modified DNA from non-malignant, benign prostatic hyperplasia (BPH), malignant and metastatic prostate tissues and in cell lines. Immunohistochemistry was performed to correlate S100A2 expression with methylation status. RESULTS: S100A6 methylation was absent or occurred at isolated sites in 14/14 cases of non-malignant epithelium and 5/5 cases of BPH tissues, whereas methylation was seen in 14/27 (52%) cases of prostatic cancer (P<0.0001), 2/2 cases of metastatic cancer and in the CWR22 prostatic cancer xenograft. Critical CpG sites within the S100A2 promoter were methylated in LNCaP, LNCaP-LN3, and CWR22 cells but not in Du145, PC3 or BPH45 cells. In tissues, S100A2 methylation was seen in 32/34 (94%) cases of adenocarcinoma and 5/5 cases of metastatic cancer. However, S100A2 methylation was also seen in 9/12 (75%) cases of non-malignant tissues and in 5/5 cases of BPH. Immunostaining, showed absent S100A2 expression all 41 cases of prostatic cancer, whereas staining was seen in the basal cells of non-malignant epithelium. CONCLUSIONS: Loss of S100A6 and S100A2 proteins is frequent in human prostatic cancer. A major mechanism underlying the loss of S100A6 expression appears to involve promoter hyper-methylation. However, mechanisms other than methylation of the known promoter are involved in silencing S100A2 in the prostate.

Netrin 1-mediated chemoattraction regulates the migratory pathway of LHRH neurons.

Luteinizing hormone-releasing hormone (LHRH) neurons migrate from the vomeronasal organ (VNO) to the forebrain in all mammals studied. In mice, the direction of LHRH neuron migration is dependent upon axons that originate in the VNO, but bypass the olfactory bulb and project caudally into the basal forebrain. Thus, factors that guide this unique subset of vomeronasal axons that comprise the caudal vomeronasal nerve (cVNN) are candidates for regulating the migration of LHRH neurons. We previously showed that deleted in colorectal cancer (DCC) is expressed by neurons that migrate out of the VNO during development [Schwarting et al. (2001) J. Neurosci., 21, 911-919]. We examined LHRH neuron migration in Dcc-/- mice and found that trajectories of the cVNN and positions of LHRH neurons are abnormal. Here we extend these studies to show that cVNN trajectories and LHRH cell migration in netrin 1 (Ntn1) mutant mice are also abnormal. Substantially reduced numbers of LHRH neurons are found in the basal forebrain and many LHRH neurons migrate into the cerebral cortex of Ntn1 knockout mice. In contrast, migration of LHRH cells is normal in Unc5h3rcm mutant mice. These results are consistent with the idea that the chemoattraction of DCC+ vomeronasal axons by a gradient of netrin 1 protein in the ventral forebrain guides the cVNN, which, in turn, determines the direction of LHRH neuron migration in the forebrain. Loss of function through a genetic deletion in either Dcc or Ntn1 results in the migration of many LHRH neurons to inappropriate destinations.

Role of the chemokine SDF-1 as the meningeal attractant for embryonic cerebellar neurons.

Migration of neuronal precursor cells from the external germinal layer (EGL) to the internal granular layer (IGL) is a crucial process in the development of the mammalian cerebellar cortex. These cells make up the only precursor population known to migrate away from the surface of the brain. We studied the role of the chemokine stromal-derived factor 1 (SDF-1) in the cerebellar tissue of rats and knockout mice and found (i) that it functions as an attractive guidance cue for neuronal migration and (ii) that its secretion from non-neuronal meningeal tissue is important for controlling the migration of embryonic EGL cells.

[Neutrophil chemotaxis. II. Clinical implications and therapeutic indications in children]. / La chemiotassi del neutrofilo. II. Implicazioni cliniche e cenni di terapia in età pediatrica.

Defects of neutrophil chemotaxis are usually accompanied by recurrent or chronic infections of the skin and the respiratory tract. The onset of clinical symptoms may occur early in infancy; infections tend to be severe and they are generally due by organisms which are of relatively low pathogenicity in the healthy subject. Abnormalities of neutrophil chemotaxis were classified and described as humoral, cellular and unclassified defects. The relevance of neutrophil chemotaxis in the single clinical entities was discussed, taking in particular account the most recent views on the argument. Some details on practical and theoretical therapeutic approaches were also reviewed.

Immunological studies on histiocytosis X. I. Special reference to the chemotactic defect and the HLA antigen.

We treated a family with three children with histiocytosis X (H-X). The chemotactic response of the neutrophils in these three patients was depressed and the chemotactic response of the neutrophils of the mother was also depressed compared to that of normal age-matched controls. To elucidate the genetic factors, we examined HLA antigens in five members of this family. All five members had Aw24, B7, Cw7, and DR1. Immunological and genetic studies in an additional 32 patients with H-X were performed. The chemotactic response of 35 patients with H-X (154.9 +/- 58.4/HPF) was significantly depressed in comparison with that of 35 age-matched healthy controls (613.3 +/- 116.7/HPF). In addition, the value of chemiluminescence of 20 of 35 patients (20.5 +/- 6.6 mV) was also significantly depressed in comparison with that of 20 normal controls (45.3 +/- 11.4 mV). The frequencies of Bw61 (54.4%) and Cw7 (45.4%) in 33 patients with H-X were significantly increased in comparison with those of 250 normal healthy controls (20.4 and 18.0%, respectively). Studies of immunoglobulin levels and complement titers of patients with H-X showed no consistent abnormalities. We proposed that defects of polymorphonuclear function may lead to an increased susceptibility to bacterial infections in patients with this disorder.

Deficient production of the lymphokine eosinophil stimulation promoter in chemically induced and mutation diabetes mellitus in mice.

The cellular defects possibly responsible for diminished in vivo granuloma formation in diabetic Schistosoma mansoni-infected mice were investigated. Diabetic and control animals develop a similar degree of eosinophilia. Eosinophils obtained from diabetic mice also respond normally to the lymphokine eosinophil stimulation promoter (ESP). Lymphoid cells of chemically induced (streptozotocin) and mutation diabetic (db/db) mice, however, have a decreased capacity to produce/secrete ESP in response to soluble egg antigens of S. mansoni. Administration of insulin to diabetic mice is associated with a partial reversal of the decreased ability of their lymphoid cells to generate ESP. These findings show that defective cellular immunity in diabetic animals may be partially explained by the failure of their lymphocytes to produce the soluble mediators involved in recruitment of target cells.