G protein-coupled receptor kinase 2 and beta-arrestins are recruited to FSH receptor in stimulated rat primary Sertoli cells

FSH-receptor (FSH-R) signaling is regulated by agonist-induced desensitization and internalization. It has been shown, in a variety of overexpression systems, that G protein-coupled receptor kinases (GRKs) phosphorylate the activated FSH-R, promote beta-arrestin recruitment and ultimately lead to internalization. The accuracy of this mechanism has not yet been demonstrated in cells expressing these different molecules at physiological levels. Using sucrose gradient fractionation, we show that FSH induces the recruitment of the endogenous GRK 2 and beta-arrestin 1/2 from the cytoplasm to the plasma membrane of rat primary Sertoli cells. As assessed by ligand binding, the FSH-R was found expressed in the fractions where GRK 2 and beta-arrestins were recruited upon FSH treatment. In addition, the endogenous beta-arrestin 1 was found dephosphorylated in an agonist-dependent manner. Finally, a significant FSH-binding activity was co-immunoprecipitated with the endogenous beta-arrestins from agonist-stimulated but not from untreated Sertoli cell extracts. This FSH-R interaction with beta-arrestins was sustained for up to 30 min. In conclusion, our data strongly suggest that the GRK/beta-arrestin machinery plays a physiologically relevant role in the regulation of the FSH signaling.     

JAM-B regulates maintenance of hematopoietic stem cells in the bone marrow

In adult mammals, hematopoietic stem cells (HSCs) reside in the bone marrow (BM) and are maintained in a quiescent and undifferentiated state through adhesive interactions with specialized microenvironmental niches. Although junctional adhesion molecule-C (JAM-C) is expressed by HSCs, its function in adult hematopoiesis remains elusive. Here, we show that HSCs adhere to JAM-B expressed by BM stromal cells in a JAM-C dependent manner. The interaction regulates the interplay between HSCs and BM stromal cells as illustrated by the decreased pool of quiescent HSCs observed in jam-b deficient mice. We further show that this is probably because of alterations of BM stromal compartments and changes in SDF-1α BM content in jam-b(-/-) mice, suggesting that JAM-B is an active player in the maintenance of the BM stromal microenvironment.     

Respiratory muscle metabolic activity on PET/CT correlates with obstructive ventilatory defect severity and prognosis in patients undergoing lung cancer surgery

Background and Objective

Respiratory muscle activity is increased in patients with chronic respiratory disease. ¹⁸F-FDG-PET/CT can assess respiratory muscle activity. We hypothesized that respiratory muscles metabolism was correlated to lung function impairment and was associated to prognosis in patients undergoing lung cancer surgery based on the research question whether respiratory muscle metabolism quantitatively correlates with the severity of lung function impairment in patients? Does respiratory muscle hypermetabolism have prognostic value?

Methods

Patients undergoing ¹⁸F-FDG-PET/CT and pulmonary function tests prior to lung cancer surgery were identified. Maximum Standardized Uptake Value (SUVm) were measured in each respiratory muscle group (sternocleidomastoid, scalene, intercostal, diaphragm), normalized against deltoid SUVm. Respiratory muscle hypermetabolism was defined as SUVm >90th centile in any respiratory muscle group. Clinical outcomes were collected from a prospective cohort.

Results

One hundred fifty-six patients were included, mostly male [110 (71%)], 53 (34%) with previous diagnosis of COPD. Respiratory muscle SUVm were: scalene: 1.84 [1.51–2.25], sternocleidomastoid 1.64 [1.34–1.95], intercostal 1.01 [0.84–1.16], diaphragm 1.79 [1.41–2.27]. Tracer uptake was inversely correlated to FEV1 for the scalene (r = −0.29, p < 0.001) and SCM (r = −0.17, p = 0.03) respiratory muscle groups and positively correlated to TLC for the scalene (r = 0.17, p = 0.04). Respiratory muscle hypermetabolism was found in 45 patients (28.8%), who had a lower VO₂ max (15.4 [14.2–17.5] vs. 17.2 mL/kg/min [15.2–21.1], p = 0.07) and poorer overall survival when adjusting to FEV1% (p < 0.01).

Conclusion

Our findings show respiratory muscle hypermetabolism is associated with lung function impairment and has prognostic significance. ¹⁸F-FDG/PET-CT should be considered as a tool for assessing respiratory muscle activity and to identify high-risk patients.     

Different cross-presentation pathways in steady-state and inflammatory dendritic cells

Presentation of exogenous antigens on MHC class I molecules, termed cross-presentation, is essential for the induction of CD8 T-cell responses and is carried out by specialized dendritic cell (DC) subsets. The mechanisms involved remain unclear. It has been proposed that antigens could be transported by endocytic receptors, such as the mannose receptor (MR) in the case of soluble ovalbumin, into early endosomes in which the cross-presentation machinery would be recruited. In these endosomal compartments, peptides would be trimmed by the aminopeptidase IRAP before loading onto MHC class I molecules. Here, we have investigated the contribution of this pathway to cross-presentation by steady-state CD8⁺ DC and inflammatory monocyte-derived DC (moDC) generated in vivo. We demonstrate that IRAP and MR are dispensable for cross-presentation by CD8⁺ DC and for cross-priming. Moreover, we could not find any evidence for diversion of endocytosed antigen into IRAP-containing endosomes in these cells. However, cross-presentation was impaired in moDC deficient in IRAP or MR, confirming the role of these two molecules in inflammatory DC. These results demonstrate that the mechanisms responsible for cross-priming by steady-state and inflammatory DC are different, which has important implications for vaccine design.     

Changes in One-Year Mortality in Elderly Patients Admitted with Acute Myocardial Infarction in Relation with Early Management

Background

Elderly patients are underrepresented in acute myocardial infarction trials. Our aim was to determine whether, in elderly patients, changes in management in the past 15 years are associated with improved 1-year mortality after hospital admission for myocardial infarction.

Abnormal activation of autophagy-induced crinophagy in Paneth cells from patients with Crohn's disease

Autophagy-related 16 like-1 (ATG16L-1), immunity-related GTPase-M (IRGM), and nucleotide-binding oligomerization domain-containing 2 (NOD2) regulate autophagy, and variants in these genes have been associated with predisposition to Crohn's disease (CD). However, little is known about the role of autophagy in CD. Intestinal biopsies from untreated pediatric patients with CD, celiac disease, or ulcerative colitis were analyzed by immunohistochemistry and electron microscopy. We observed that autophagy was specifically activated in Paneth cells from patients with CD, independently of mucosal inflammation or disease-associated variants of ATG16L1 or IRGM. In these cells, activation of autophagy was associated with a significant decrease in number of secretory granules and features of crinophagy. These observations might account for the disorganization of secretory granules previously reported in Paneth cells from patients with CD.     

SPECT low-field MRI system for small-animal imaging.

Localization of regions with increased uptake of radiotracer in small-animal SPECT is greatly facilitated when using coregistration with anatomic images of the same animal. As MRI has several advantages compared with CT (soft-tissue contrast and lack of ionizing radiation) we developed a SPECT/low-field MRI hybrid device for small-animal imaging. METHODS: A small-animal single-pinhole gamma-camera (pinhole, 1.5 mm in diameter and 12 cm in focal length) adjacent to a dedicated low-field (0.1 T) small MR imager (imaging volume, 10 x 10 x 6 cm(3)) was used. The animal was placed in a warmed nonmagnetic polymethyl methacrylate imaging cell for MR acquisition, which was followed immediately by SPECT after translation of the imaging cell from one modality to the other. 3-Dimensional T1-weighted sequences were used for MRI. Phantom studies enabled verification of a low attenuation (10%) for (99m)Tc and (201)Tl and a very slight increase in Compton scattering due to the radiofrequency coil and polymethyl methacrylate imaging cell. RESULTS: SPECT/MRI data acquisition and image coregistration of selected examples using different radiotracers for lungs, kidneys, and brain were obtained in 3 nude mice with isotropic spatial resolutions of 0.5 x 0.5 x 0.5 mm(3) for MRI and 1 x 1 x 1 mm(3) for SPECT. The total acquisition time for combined SPECT and MRI lasted 1 h 45 min. CONCLUSION: A low-magnetic-field strength of 0.1 T is a simple and useful solution for a small-animal dual-imaging device combining pinhole SPECT with the adjacent MR imager.