Tolerogenic dendritic cells induced by vitamin D receptor ligands enhance regulatory T cells inhibiting allograft rejection and autoimmune diseases

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Cutting Edge: Selective Usage of Chemokine Receptors by Plasmacytoid Dendritic Cells

Abstract The existence of dendritic cell (DC) subsets is firmly established, but their trafficking properties are virtually unknown. In this study, we show that myeloid (M-DCs) and plasmacytoid (P-DCs) DCs isolated from human blood differ widely in the capacity to migrate to chemotactic stimuli. The pattern of chemokine receptors expressed by blood M-DCs and P-DCs, with the exception of CCR7, is similar. However, most chemokine receptors of P-DCs, in particular those specific for inflammatory chemokines and classical chemotactic agonists, are not functional in circulating cells. Following maturation induced by CD40 ligation, the receptors for inflammatory chemokines are down-regulated, and CCR7 on P-DCs becomes coupled to migration. The drastically impaired capacity of blood P-DCs to migrate in response to inflammatory chemotactic signals contrasts with the response to lymph node-homing chemokines, indicating a propensity to migrate to secondary lymphoid organs rather than to sites of inflammation

variations of salivary cortisol in dogs exposed to different cognitive and physical activities

Working dogs are gaining popularity for their ability to learn and perform tasks entertaining their human companions. For this reason, dogs are often subjected to various stimuli due to inter- and intra-specific interactions, environmental variations and effort required by different activities. In the present study, salivary cortisol was measured to monitor physiological response to different conditions. The first study was performed to assess the variability of salivary cortisol in dogs in usual environmental conditions. For this, salivary cortisol was measured in 10 dogs at home during three not consecutive days at three different times of the day and not significant variations between days and time of sampling were observed. In the second study, salivary cortisol was measured in dogs before and after Pointing Hunting (No. 5), Tracking for Ungulate Hunting (No. 6), Blood Tracking (No. 4), Agility Training (No. 6) and Animal Assisted Activities (AAA, No. 6). Salivary cortisol concentration significantly increased after the Pointing Hunting activity (p < .05), while salivary cortisol significantly decreased at the end of AAA session (p < .05). No significant differences in cortisol variations were observed for Tracking for Ungulate Hunting, Blood Tracking and Agility Training, before and after the activities. The response of cortisol suggests that the extent of hypothalamus–pituitary–adrenal axis activation varies between short high-intensity activities and endurance exercises. The measurement of salivary cortisol can support the trainers to evaluate the animal response to the stimulations

Cutting edge: differential chemokine production by myeloid and plasmacytoid dendritic cells.

Abstract To examine the different roles of myeloid dendritic cells (M-DCs) and plasmacytoid dendritic cells (P-DCs) in the induction and regulation of immune response, we have studied chemokine secretion by freshly isolated DC subsets in response to bacterial, viral, and T cell-derived stimuli. M-DCs selectively produced very high levels of the homeostatic chemokines CC chemokine ligand (CCL)17 and CCL22, while P-DCs produced very little if any. In contrast, the proinflammatory chemokine CCL3 was secreted mostly by P-DCs, whereas CCL4 and CXC chemokine ligand 8 were produced by both subsets. The selective production of CCL17 and CCL22 by M-DCs but not P-DCs was confirmed in vivo by immunohistology on human reactive lymph node sections. The high production of CCR4 ligands by M-DCs suggests their capacity to selectively recruit at sites of inflammation T cells with regulatory properties or with a Th2 phenotype, whereas P-DCs, by preferentially secreting CCR1/CCR5 ligands, would mostly recruit effector T cells and, in particular, Th1-type cells

FXR and TGR5 Agonists Ameliorate Liver Injury, Steatosis, and Inflammation After Binge or Prolonged Alcohol Feeding in Mice

Bile acids (BAs) activate various dedicated receptors, including the farnesoid X receptor (FXR) and the Takeda G protein-coupled receptor 5 (TGR5). The FXR agonist obeticholic acid (OCA) is licensed for the treatment of primary biliary cholangitis and has shown promising results in NASH patients, whereas TGR5 agonists target inflammation and metabolism. We hypothesized that FXR and/or TGR5 agonists may be therapeutic in early alcoholic liver disease (ALD) in mice, in which hepatic inflammation plays a major role. OCA, INT-777, and INT-767 are BA derivatives with selective agonist properties for FXR, TGR5, or both, respectively. These compounds were tested in two mouse models (3-day binge model and prolonged Lieber DeCarli diet for 12 days) of early ALD. Serum alanine aminotransferase and liver histology were used to assess liver injury, Oil Red O staining of liver sections to assess steatosis, and real-time polymerase chain reaction to assess changes in gene expression. In the ethanol binge model, treatment with OCA and INT-777 decreased hepatic macrovesicular steatosis and protected from ethanol-induced liver injury. After prolonged ethanol administration, mice treated with OCA, INT-767, or INT-777 showed decreased hepatic steatosis, associated with reduced liver fatty acid synthase protein expression, and protection from liver injury. Treatment with BA receptor agonists in both models of ethanol administration modulated lipogenic gene expression, and decreased liver interleukin-1beta mRNA expression associated with increased ubiquitination of NLRP3 inflammasome through cyclic adenosine monophosphate-induced activation of protein kinase A. Conclusion: OCA, INT-767, or INT-777 administration is effective in reducing acute and chronic ethanol-induced steatosis and inflammation in mice, with varying degrees of efficacy depending on the duration of ethanol administration, indicating that both FXR and TGR5 activation can protect from liver injury in ALD models

1,25-Dihydroxyvitamin D3 selectively modulates tolerogenic properties in myeloid but not plasmacytoid dendritic cells

1,25-Dihydroxy vitamin D3 (1,25(OH)2D3) is an immunomodulatory agent inducing dendritic cells (DCs) to become tolerogenic. To further understand its mechanisms of action, we have examined the effects of 1,25(OH)2D3 on tolerogenic properties of blood myeloid (M-DCs) and plasmacytoid (P-DCs) human DC subsets. Exposure of M-DCs to 1,25(OH)2D3 up-regulated production of CCL22, a chemokine attracting regulatory T cells, whereas production of CCL17, the other CCR4 ligand, was reduced. 1,25(OH)2D3 also decreased IL-12p75 production by M-DCs, as expected, and inhibited CCR7 expression. 1,25(OH) 2D3 treatment markedly increased CD4+ suppressor T cell activity while decreasing the capacity of M-DCs to induce Th1 cell development. Surprisingly, 1,25(OH)2D3 did not exert any discernible effect on tolerogenic properties of P-DCs, and even their high production of IFN-α was not modulated. In particular, the intrinsically high capacity of P-DCs to induce CD4+ suppressor T cells was unaffected by 1,25(OH)2D3. Both DC subsets expressed similar levels of the vitamin D receptor, and its ligation by 1,25(OH) 2D3 similarly activated the primary response gene cyp24. Interestingly, 1,25(OH)2D3 inhibited NF-κB p65 phosphorylation and nuclear translocation in M-DCs but not P-DCs, suggesting a mechanism for the inability of 1,25(OH)2D3 to modulate tolerogenic properties in P-DCs.Fil: Penna, Giuseppe. No especifíca;Fil: Amuchastegui, Susana. No especifíca;Fil: Giarratana, Nadia. No especifíca;Fil: Daniel, Kenn C.. No especifíca;Fil: Vulcano, Marisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Sozzani, Silvano. No especifíca;Fil: Adorini, Luciano. No especifíca

1,25-Dihydroxyvitamin D3 selectively modulates tolerogenic properties in myeloid but not plasmacytoid dendritic cells

1,25-Dihydroxy vitamin D3 (1,25(OH)2D3) is an immunomodulatory agent inducing dendritic cells (DCs) to become tolerogenic. To further understand its mechanisms of action, we have examined the effects of 1,25(OH)2D3 on tolerogenic properties of blood myeloid (M-DCs) and plasmacytoid (P-DCs) human DC subsets. Exposure of M-DCs to 1,25(OH)2D3 up-regulated production of CCL22, a chemokine attracting regulatory T cells, whereas production of CCL17, the other CCR4 ligand, was reduced. 1,25(OH)2D3 also decreased IL-12p75 production by M-DCs, as expected, and inhibited CCR7 expression. 1,25(OH) 2D3 treatment markedly increased CD4+ suppressor T cell activity while decreasing the capacity of M-DCs to induce Th1 cell development. Surprisingly, 1,25(OH)2D3 did not exert any discernible effect on tolerogenic properties of P-DCs, and even their high production of IFN-α was not modulated. In particular, the intrinsically high capacity of P-DCs to induce CD4+ suppressor T cells was unaffected by 1,25(OH)2D3. Both DC subsets expressed similar levels of the vitamin D receptor, and its ligation by 1,25(OH) 2D3 similarly activated the primary response gene cyp24. Interestingly, 1,25(OH)2D3 inhibited NF-κB p65 phosphorylation and nuclear translocation in M-DCs but not P-DCs, suggesting a mechanism for the inability of 1,25(OH)2D3 to modulate tolerogenic properties in P-DCs.Fil: Penna, Giuseppe. No especifíca;Fil: Amuchastegui, Susana. No especifíca;Fil: Giarratana, Nadia. No especifíca;Fil: Daniel, Kenn C.. No especifíca;Fil: Vulcano, Marisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Sozzani, Silvano. No especifíca;Fil: Adorini, Luciano. No especifíca

The FXR agonist obeticholic acid inhibits the cancerogenic potential of human cholangiocarcinoma

Cholangiocarcinoma (CCA) is an aggressive cancer with high resistance to chemotherapeutics. CCA is enriched in cancer stem cells, which correlate with aggressiveness and prognosis. FXR, a member of the metabolic nuclear receptor family, is markedly down-regulated in human CCA. Our aim was to evaluate, in primary cultures of human intrahepatic CCA (iCCA), the effects of the FXR agonist obeticholic acid (OCA), a semisynthetic bile acid derivative, on their cancerogenic potential. Primary human iCCA cell cultures were prepared from surgical specimens of mucinous or mixed iCCA subtypes. Increasing concentrations (0–2.5 μM) of OCA were added to culture media and, after 3–10 days, effects on proliferation (MTS assay, cell population doubling time), apoptosis (annexin V-FITC/propidium iodide), cell migration and invasion (wound healing response and Matrigel invasion assay), and cancerogenic potential (spheroid formation, clonogenic assay, colony formation capacity) were evaluated. Results: FXR gene expression was downregulated (RT-qPCR) in iCCA cells vs normal human biliary tree stem cells (p < 0.05) and in mucinous iCCA vs mixed iCCA cells (p < 0.05) but was upregulated by addition of OCA. OCA significantly (p < 0.05) inhibited proliferation of both mucinous and mixed iCCA cells, starting at a concentration as low as 0.05 μM. Also, CDCA (but not UDCA) inhibited cell proliferation, although to a much lower extent than OCA, consistent with its different affinity for FXR. OCA significantly induced apoptosis of both iCCA subtypes and decreased their in vitro cancerogenic potential, as evaluated by impairment of colony and spheroid formation capacity and delayed wound healing and Matrigel invasion. In general, these effects were more evident in mixed than mucinous iCCA cells. When tested together with Gemcitabine and Cisplatin, OCA potentiated the anti-proliferative and pro-apoptotic effects of these chemotherapeutics, but mainly in mixed iCCA cells. OCA abolished the capacity of both mucinous and mixed iCCA cells to form colonies when administered together with Gemcitabine and Cisplatin. In subcutaneous xenografts of mixed iCCA cells, OCA alone or combined with Gemcitabine or Cisplatin markedly reduced the tumor size after 5 weeks of treatment by inducing necrosis of tumor mass and inhibiting cell proliferation. In conclusion, FXR is down-regulated in iCCA cells, and its activation by OCA results in anti-cancerogenic effects against mucinous and mixed iCCA cells, both in vitro and in vivo. The effects of OCA predominated in mixed iCCA cells, consistent with the lower aggressiveness and the higher FXR expression in this CCA subtype. These results, showing the FXR-mediated capacity of OCA to inhibit cholangiocarcinogenesis, represent the basis for testing OCA in clinical trials of CCA patients