The soluble glycoprotein NMB (GPNMB) produced by macrophages induces cancer stemness and metastasis via CD44 and IL-33.

In cancer, myeloid cells have tumor-supporting roles. We reported that the protein GPNMB (glycoprotein nonmetastatic B) was profoundly upregulated in macrophages interacting with tumor cells. Here, using mouse tumor models, we show that macrophage-derived soluble GPNMB increases tumor growth and metastasis in Gpnmb-mutant mice (DBA/2J). GPNMB triggers in the cancer cells the formation of self-renewing spheroids, which are characterized by the expression of cancer stem cell markers, prolonged cell survival and increased tumor-forming ability. Through the CD44 receptor, GPNMB mechanistically activates tumor cells to express the cytokine IL-33 and its receptor IL-1R1L. We also determined that recombinant IL-33 binding to IL-1R1L is sufficient to induce tumor spheroid formation with features of cancer stem cells. Overall, our results reveal a new paracrine axis, GPNMB and IL-33, which is activated during the cross talk of macrophages with tumor cells and eventually promotes cancer cell survival, the expansion of cancer stem cells and the acquisition of a metastatic phenotype.

Myostatin mediates abdominal aortic atherosclerosis progression by inducing vascular smooth muscle cell dysfunction and monocyte recruitment.

Myostatin (Mstn) is a skeletal muscle growth inhibitor involved in metabolic disorders and heart fibrosis. In this study we sought to verify whether Mstn is also operative in atherosclerosis of abdominal aorta. In human specimens, Mstn expression was almost absent in normal vessels, became detectable in the media of non-progressive lesions and increased with the severity of the damage. In progressive atherosclerotic lesions, Mstn was present in the media, neointima, plaque shoulder and in infiltrating macrophages. Mstn co-localized with α-smooth muscle actin (α-SMA) staining and with some CD45+ cells, indicating Mstn expression in VSMCs and bloodstream-derived leukocytes. In vitro, Mstn was tested in VSMCs and monocytes. In A7r5 VSMCs, Mstn downregulated proliferation and Smoothelin mRNA, induced cytoskeletal rearrangement, increased migratory rate and MCP-1/CCR2 expression. In monocytes (THP-1 cells and human monocytes), Mstn acted as a chemoattractant and increased the MCP-1-dependent chemotaxis, F-actin, α-SMA, MCP-1 and CCR2 expression; in turn, MCP-1 increased Mstn mRNA. Mstn induced JNK phosphorylation both in VSMCs and monocytes. Our results indicate that Mstn is overexpressed in abdominal aortic wall deterioration, affects VSMCs and monocyte biology and sustains a chronic inflammatory milieu. These findings propose to consider Mstn as a new playmaker in atherosclerosis progression.

Immunohistochemical characterization of thymic macrophages in normal and treated rats: a differential sensitivity to cyclosporine A.

In the present study, a set of two monoclonal antibodies (TRPM1, TRPM2) was used to investigate the macrophage populations in the rat thymus and their different sensitivities to cyclosporine-A (CsA). With double immunohistochemical staining we demonstrated that, in the normal rat thymus, there are 3 populations of macrophages (TRPM1+, TRPM1/2+, TRPM2+), present in different proportions throughout the thymus. In the outer cortex TRPM1+ and TRPM1/2+ were present, but the TRPM1/2+ cells were more numerous. No TRPM2+ cells were observed in this area. The cortex and medulla showed all 3 types of cells with a majority of TRPM1/2+ cells. In the corticomedullary zone (CMZ) TRPM1/2+ and TRPM2+ macrophages were present in about equal proportion while only a few TRPM1+ cells were observed. After CsA treatment (for 21 days) profound changes occurred in the thymus; we observed a complete disappearance of the thymic medulla and a reduction in the total number of macrophages. The TRPM1+ macrophages had been eliminated, a few TRPM1/2+ cells were found while many of the cells were TRPM2+. The presence of the macrophages in different thymic areas suggests that they are a very heterogeneous population. The possible significance of the macrophage heterogeneity and the relationship to CsA sensitivity is discussed.

Experimental repair of spinal cord lesions by grafting from CNS to PNS.

Based on the previous work of other researchers, we first removed 1 cm of the spinal cord of rats and grafted the gap with peripheral nerve. We obtained progression of regenerating axons inside the grafts, but regrowing axons halted at the distal cord level. We then tried directly to connect the cephalad stump of the cord with the sciatic nerve, several surgical models of which have been previously studied. The latest model uses a homologous sciatic nerve of an inbred Wistar rat, to bridge the gap between the lateral bundle of the cord, proximal to the origin of the sciatic roots, and the sciatic trunk distal to the fusion of its roots. Good reinnervation of the sciatic nerve and distal muscles was found. It was demonstrated by: a) the remyelination of regenerated nerve fibers, not only in the grafts but also in the sciatic nerve; b) re-innervation of motor endplates; and c) clinical and electromyographic muscle responses. Central nervous system (CNS) neurons are able to regenerate not only their axons through the CNS but also into peripheral nerves. The capacity of CNS neurons to neurotize peripheral nerves reaching terminal organs, is a basic finding. Many questions arise from the study, including: Can these results be extrapolated to humans? What would be the function of these regenerated fibers that might lack some of the control mechanisms peculiar to peripheral nerves?

Fibronectin distribution during lymph node development in guinea pig: an immunohistochemical study.

We carried out an immunohistochemical study on mesenteric guinea pig lymph nodes, from the 10th day prepartum till the 26th day postpartum, to assess the role of fibronectin in their organization during development. This glycoprotein is diffusely distributed in embryonic lymph nodes, suggesting a primer function during organogenesis. After birth, in fact, it is less widespread and is mainly localized around sinuses and vessels. Our data, supporting the important role of this glycoprotein during lymph node organization, are in agreement with the results obtained in other tissues and organs.

Morphological characterization of stationary reticulum cells of the stromal in the mesenteric lymph node of the guinea pig.

The large mesenteric lymph node taken from guinea pigs in a period of time ranging from the 10th day prepartum till the 26th day postpartum has been examined in order to study: the morphological features of the stromal stationary reticulum cells with particular regard to recognize their stages of development; the possible ontogenetic relationship between these cells during the maturation of the lymphoid tissue. Our data support the hypothesis that from local mesenchymal cells originates a pool of poorly differentiated reticulum cells that can give rise to stromal stationary reticulum cells (myofibroblast-like cells, fibroblast-like cells, pericyte-like cells and dendritic cells). These elements have a characteristic distribution pattern likely related to different local functional requirements.

The ultrastructure of the nucleus of the oculomotor nerve (somatic efferent portion) of the cat.

The ultrastructure of the somatic efferent portion of the nucleus of the oculomotor nerve was studied in four adult cats. The neuronal population is composed of neurons of variable size. A continuous pattern of morphological aspects is evident between the large neurons, which show abundant cytoplasm with well developed organelles, and the small neurons which have a reduced amount of cytoplasm. The dendrites are generally smooth, with few short spines. Axo-dendritic synapses are numerous. Synaptic boutons are also present on the axon hillock. The neuropil is characterized by the occurrence of small groups of dendrites which may be in direct touch with their membranes. Direct membrane appositions may also occur between neighbouring neurons and between the cell somata and tangentially running dendrites. Generally beneath the site of apposition there is accumulation of mitochondria, multivesicular bodies, coated vesicles and moderately dense amorphous material. The morphological features suggest the possibility of cellular interchanges at the sites of direct membrane apposition. Five types of synaptic boutons were recognized on the basis of their vesicular content, the presence of abundant filaments in the pre-synaptic bag, the occurrence of post-synaptic specializations. The different synaptic types and their distribution are similar to those reported in the spinal motor nuclei. Many of the synapses make synaptic contacts with two or more post-synaptic elements. Axo-axonic synapses were also observed.