Mouse Bone Marrow-Derived Mesenchymal Stromal Cells Turn Activated Macrophages into a Regulatory-Like Profile

In recent years it has become clear that the therapeutic properties of bone marrow-derived mesenchymal stromal cells (MSC) are related not only to their ability to differentiate into different lineages but also to their capacity to suppress the immune response. We here studied the influence of MSC on macrophage function. Using mouse thioglycolate-elicited peritoneal macrophages (M) stimulated with LPS, we found that MSC markedly suppressed the production of the inflammatory cytokines TNF-α, IL-6, IL-12p70 and interferon-γ while increased the production of IL-10 and IL-12p40. Similar results were observed using supernatants from MSC suggesting that factor(s) constitutively released by MSC are involved. Supporting a role for PGE2 we observed that acetylsalicylic acid impaired the ability of MSC to inhibit the production of inflammatory cytokines and to stimulate the production of IL-10 by LPS-stimulated M. Moreover, we found that MSC constitutively produce PGE2 at levels able to inhibit the production of TNF-α and IL-6 by activated M. MSC also inhibited the up-regulation of CD86 and MHC class II in LPS-stimulated M impairing their ability to activate antigen-specific T CD4+ cells. On the other hand, they stimulated the uptake of apoptotic thymocytes by M. Of note, MSC turned M into cells highly susceptible to infection with the parasite Trypanosoma cruzi increasing more than 5-fold the rate of M infection. Using a model of inflammation triggered by s.c. implantation of glass cylinders, we found that MSC stimulated the recruitment of macrophages which showed a low expression of CD86 and the MHC class II molecule Iab and a high ability to produce IL-10 and IL-12p40, but not IL-12 p70. In summary, our results suggest that MSC switch M into a regulatory profile characterized by a low ability to produce inflammatory cytokines, a high ability to phagocyte apoptotic cells, and a marked increase in their susceptibility to infection by intracellular pathogens

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic

Chronic lymphocytic leukemia cells bind and present the erythrocyte protein band 3: Possible role as initiators of autoimmune hemolytic anemia

The mechanisms underlying the frequent association between chronic lymphocytic leukemia (CLL) and autoimmune hemolytic anemia are currently unclear. The erythrocyte protein band 3 (B3) is one of the most frequently targeted Ags in autoimmune hemolytic anemia. In this study, we show that CLL cells specifically recognize B3 through a still unidentified receptor. B3 interaction with CLL cells involves the recognition of its N-terminal domain and leads to its internalization. Interestingly, when binding of erythrocyte-derived vesicles as found physiologically in blood was assessed, we observed that CLL cells could only interact with inside-out vesicles, being this interaction strongly dependent on the recognition of the N-terminal portion of B3. We then examined T cell responses to B3 using circulating CLL cells as APCs. Resting B3-pulsed CLL cells were unable to induce T cell proliferation. However, when deficient costimulation was overcome by CD40 engagement, B3-pulsed CLL cells were capable of activating CD4+ T cells in a HLA-DR-dependent fashion. Therefore, our work shows that CLL cells can specifically bind, capture, and present B3 to T cells when in an activated state, an ability that could allow the neoplastic clone to trigger the autoaggressive process against erythrocytes. Copyright © 2008 by The American Association of Immunologists, Inc.Fil: Galletti, Jeremías Gastón. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Cañones, Cristian. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Morande, Pablo Elías. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Borge, Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Oppezzo, Pablo. Instituto Pasteur de Montevideo; UruguayFil: Geffner, Jorge Raúl. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Bezares, Raimundo F.. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Dr. Teodoro Álvarez"; ArgentinaFil: Gamberale, Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Giordano, Mirta Nilda. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; Argentin

Acetylsalicylic acid (ASA) impairs the ability of MSC to modulate the profile of cytokines produced by M.

<p>(A) M were cultured overnight in the absence or presence of MSC (M: MSC ratio = 10∶1) with or without ASA (0.5 mM). Cells were then washed and incubated for 18 h with LPS (30 ng/ml), in the absence or presence of ASA (0.5 mM) and cytokines were analyzed in cell-supernatants by ELISA. (B) M were cultured overnight in the absence (controls) or presence of different concentrations of PGE2. Then, cells were incubated for 18 h with LPS (30 ng/ml) and cytokines were analyzed in cell-supernatants by ELISA. Results are expressed in pg/ml and represent the arithmetic mean ± SEM of 4–5 experiments. *, p<0.05 for M+MSC+ASA vs M+MSC, and for M+LPS+PGE2 vs M+LPS.</p

MSC stimulate “in vivo” the recruitment of macrophages and direct their differentiation into a regulatory-like profile.

<p>A Glass cylinder of 2 cm long, 8 mm wide and around 200 µl internal volume was implanted s.c. into 8-to 12-week-old C57BL/6 mice. Two and 7 days after the cylinders were implanted in the mice, 2×10⁵ MSC in 50 µl of pyrogen free-PBS or PBS alone (controls) were inoculated inside the cylinders, using a 22 g needle. After 15 days the liquid content of the cylinders was aspirated and the levels of the cytokines TNF-α, IL-12p70, IL-12p40 and IL-10 were determined by ELISA (D). Cylinders were removed, washed with saline and placed in cold PBS (4°C) for 30 min. Adherent cells (>90% macrophages) were removed from the interior of each cylinder to obtain a single cell suspension. The number of the macrophages recruited in each cylinder was measured (A), and their expression of Ia^b and CD86 was analyzed by flow cytometry (B-C). Results represent the arithmetic mean ± SEM (n = 12 for each experimental group). *, p<0.05 for Controls (CT) vs MSC.</p

MSC regulate the profile of cytokines produced by activated M through the release of soluble factor(s).

<p>MSC grown to confluence were cultured alone for 24 h and the cell-supernatants were then harvested. M were cultured for 18 h with or without LPS (30 ng/ml) in the absence or presence of MSC supernatants (50% V/V) and cytokines were analyzed in cell-supernatants by ELISA. Results are expressed in pg/ml and represent the arithmetic mean ± SEM of 5 experiments. *, p<0.05 for M+Sn+LPS vs M+LPS.</p

MSC inhibit the production of inflammatory cytokines and enhance the production of IL-10 by thioglycolate-elicited peritoneal macrophages (M).

<p>M were cultured overnight in the absence or presence of MSC (M: MSC ratio = 10∶1). Cells were then washed and incubated for 18 h with or without LPS (30 ng/ml), and cytokines were analyzed in cell-supernatants by ELISA (A and C) or by intracellular staining and flow cytometry (B). (A and C) Results are expressed in pg/ml and represent the arithmetic mean ± SEM of 5–6 experiments. (B) Representative dot-plots (n = 4) are shown. Inside the circle MSC. *, p<0.05 for M+MSC+LPS vs M+LPS.</p

Characterization of bone marrow-derived mesenchymal stromal cells (MSC).

<p>MSC were isolated from bone marrow of adult C57BL/6J and cultured using standard protocols. (A) Analysis of the phenotype of MSC by flow cytometry. Grey histograms represent isotype controls (B) Morphology of MSC. (C) Culture of MSC in adipocyte-differentiation media showing cells containing drops of fat revealed by Oil Red O. (D) Culture of MSC in osteogenic-differentiation media showing the formation of calcium containing precipitates stained by Alizarin Red S. A representative experiment is shown.</p