Cathal McCarthy

Mesenchymal stem cell inhibition of T-helper 17 cell- differentiation is triggered by cell–cell contact and mediated by prostaglandin E2 via the EP4 receptor

Mesenchymal stem cells (MSCs) inhibit T‐cell activation and proliferation but their effects on individual T‐cell‐effector pathways and on memory versus naïve T cells remain unclear. MSC influence on the differentiation of naïve and memory CD4+ T cells toward the Th17 phenotype was examined. CD4+ T cells exposed to Th17‐skewing conditions exhibited reduced CD25 and IL‐17A expression following MSC co‐culture. Inhibition of IL‐17A production persisted upon re‐stimulation in the absence of MSCs. These effects were attenuated when cell–cell contact was prevented. Th17 cultures from highly purified naïve‐ and memory‐phenotype responders were similarly inhibited. Th17 inhibition by MSCs was reversed by indomethacin and a selective COX‐2 inhibitor. Media from MSC/Th17 co‐cultures contained increased prostaglandin E2 (PGE2) levels and potently suppressed Th17 differentiation in fresh cultures. MSC‐mediated Th17 inhibition was reversed by a selective EP4 antagonist and was mimicked by synthetic PGE2 and a selective EP4 agonist. Activation‐induced IL‐17A secretion by naturally occurring, effector‐memory Th17 cells from a urinary obstruction model was also inhibited by MSC co‐culture in a COX‐dependent manner. Overall, MSCs potently inhibit Th17 differentiation from naïve and memory T‐cell precursors and inhibit naturally‐occurring Th17 cells derived from a site of inflammation. Suppression entails cell‐contact‐dependent COX‐2 induction resulting in direct Th17 inhibition by PGE2 via EP4.

IL-10 mediates the immunoregulatory response in conjugated linoleic acid-induced regression of atherosclerosis

Conjugated linoleic acid (CLA) induces regression of preestablished atherosclerosis in the ApoE–/– mouse. Understanding the mechanisms involved may help in identifying novel pathways associated with the regression of human disease. Animals were administered a 1% cholesterol diet for 12 wk, with 1% CLA supplementation from wk 8 to 12. ApoE–/– mice fed only the 1% cholesterol diet for 12 wk were employed as controls. Transcriptomic analysis of mouse aorta showed that many of the components of the IL‐10 signaling pathway were modified during CLA‐induced regression. Real‐time PCR and Western blot analysis showed increased IL‐10 receptor expression, phosphorylation of STAT3, and downstream target gene expression in the aorta, alongside an increase in serum IL‐10 (79.8±22.4 vs. 41.9±5.5 pg/ml, n=10; P<0.01). CLA ‐supplementation also increased IL‐10 production in bone marrow‐derived macrophages (143.6±28.6 vs. 94±5.6 pg/ml, n=5; P<0.05). To explore the mechanisms for altered IL‐10 production, we examined the profile of monocyte/macrophage phenotype in the vessel wall, bone marrow, and spleen. CLA increased macrophage polarization toward an anti‐inflammatory M2 phenotype in vivo, increasing the population of Ly6Clo monocytes (29 vs. 77±14, n=5, P < 0.05) in the aorta. CLA had similar effects on monocytes/macrophages differentiated from marrow‐derived progenitor cells and on splenocytes. The induction of IL‐10 on CLA supplementation in this model may reflect a systemic alteration toward an anti‐inflammatory phenotype, which, in turn promotes increased vascular infiltration by Ly6Clo monocytes. These cells may contribute to CLA‐induced disease regression.—McCarthy, C., Duffy, M. M., Mooney, D., James, W. G., Griffin, M. D., Fitzgerald, D. J., Belton, O. IL‐10 mediates the immunoregulatory response in conjugated linoleic acid‐induced regression of atherosclerosis. FASEB J. 27, 499–510 (2013). www.fasebj.org

Macrophage PPAR gamma Co-activator-1 alpha participates in repressing foam cell formation and atherosclerosis in response to conjugated linoleic acid

Conjugated linoleic acid (CLA) has the unique property of inducing regression of pre‐established murine atherosclerosis. Understanding the mechanism(s) involved may help identify endogenous pathways that reverse human atherosclerosis. Here, we provide evidence that CLA inhibits foam cell formation via regulation of the nuclear receptor coactivator, peroxisome proliferator‐activated receptor (PPAR)‐γ coactivator (PGC)‐1α, and that macrophage PGC‐1α plays a role in atheroprotection in vivo. PGC‐1α was identified as a hub gene within a cluster in the aorta of the apoE−/− mouse in the CLA‐induced regression model. PGC‐1α was localized to macrophage/foam cells in the murine aorta where its expression was increased during CLA‐induced regression. PGC‐1α expression was also detected in macrophages in human atherosclerosis and was inversely linked to disease progression in patients with the disease. Deletion of PGC‐1α in bone marrow derived macrophages promoted, whilst over expression of the gene inhibited foam cell formation. Importantly, macrophage specific deletion of PGC‐1α accelerated atherosclerosis in the LDLR−/− mouse in vivo. These novel data support a functional role for PGC‐1α in atheroprotection.

Standardization of models and methods used to assess nanoparticles in cardiovascular applications.

Nanotechnology has the potential to revolutionize the management and treatment of cardiovascular disease. Controlled drug delivery and nanoparticle-based molecular imaging agents have advanced cardiovascular disease therapy and diagnosis. However, the delivery vehicles (dendrimers, nanocrystals, nanotubes, nanoparticles, nanoshells, etc.), as well as the model systems that are used to mimic human cardiac disease, should be questioned in relation to their suitability. This review focuses on the variations of the biological assays and preclinical models that are currently being used to study the biocompatibility and suitability of nanomaterials in cardiovascular applications. There is a need to standardize appropriate models and methods that will promote the development of novel nanomaterial-based cardiovascular therapies.

Maternal chorionic gonadotrophin concentration as an aid to the antenatal prediction of hemolytic disease of newborn infant

Abstract 1. 1. The maternal HCG serum level was found to be enormously increased in mothers whose infants were subsequently hydropic but was within normal limits in all other degrees of hemolytic disease. 2. 2. It is suggested that the elevated HCG levels found in the maternal serum in hydrops fetalis does not occur before the development of this condition.

Immunological determination of chorionic gonadotropin in liquor amnii and its application in Rh incompatibility

Abstract 1. 1. The normally occurring concentrations of human chorionic gonadotropin (HCG) in liquor amnii at the end of pregnancy have been investigated in a series of 18 patients. A range of values between 0 and 2,400 I.U. per liter with a mean of 731 ± 180 I.U. per liter have been observed. 2. 2. In hydrops fetalis, the maternal serum gonadotropin level is raised. Because of the intimate contact between the placenta and liquor amnii, the liquor chorionic gonadotropin concentrations were investigated in a series of 16 Rh-sensitized women. A range of values were found between 0 and 1,100 I.U. per liter with a mean of 409 ± 82 I.U. per liter. There was no statistical difference between the two series. 3. 3. In one case, where a stillborn hydropic fetus was delivered the HCG concentration was within normal limits. This suggests that there is little correlation between serum and liquor levels, and supports the data of other workers. 4. 4. It is concluded that estimation of the HCG content of liquor does not provide a means of determining fetal damage due to Rh-immunization prior to delivery.

Therapeutically targeting mitochondrial redox signalling alleviates endothelial dysfunction in preeclampsia

Aberrant placentation generating placental oxidative stress is proposed to play a critical role in the pathophysiology of preeclampsia. Unfortunately, therapeutic trials of antioxidants have been uniformly disappointing. There is provisional evidence implicating mitochondrial dysfunction as a source of oxidative stress in preeclampsia. Here we provide evidence that mitochondrial reactive oxygen species mediates endothelial dysfunction and establish that directly targeting mitochondrial scavenging may provide a protective role. Human umbilical vein endothelial cells exposed to 3% plasma from women with pregnancies complicated by preeclampsia resulted in a significant decrease in mitochondrial function with a subsequent significant increase in mitochondrial superoxide generation compared to cells exposed to plasma from women with uncomplicated pregnancies. Real-time PCR analysis showed increased expression of inflammatory markers TNF-α, TLR-9 and ICAM-1 respectively in endothelial cells treated with preeclampsia plasma. MitoTempo is a mitochondrial-targeted antioxidant, pre-treatment of cells with MitoTempo protected against hydrogen peroxide-induced cell death. Furthermore MitoTempo significantly reduced mitochondrial superoxide production in cells exposed to preeclampsia plasma by normalising mitochondrial metabolism. MitoTempo significantly altered the inflammatory profile of plasma treated cells. These novel data support a functional role for mitochondrial redox signaling in modulating the pathogenesis of preeclampsia and identifies mitochondrial-targeted antioxidants as potential therapeutic candidates.

Immunostimulatory role of mitochondrial DAMPs: alarming for pre-eclampsia?

Mitochondria are critical signaling organelles that play an integral cellular role in the activation of diverse physiological responses to perturbation. Mitochondrial damage‐associated molecular patterns (DAMPs) act as redox signaling nodes synchronizing mitochondrial metabolism with triggering of inflammation. Oxidative stress and inflammation are implicated in the pathogenesis of pre‐eclampsia; however, the mechanisms involved in the novel crosstalk between these two pathogenic pathways are less well elucidated. In this review, we show that mitochondrial redox signals are paramount for regulating and maintaining the inflammatory response to danger signals. Mitochondrial DNA (mtDNA) represents a mitochondrial DAMP and is often liberated as signal of mitochondrial dysfunction. This review will explore the mechanistic role of mitochondrial DNA in directly coordinating adaptive changes in the maternal inflammatory status in pre‐eclampsia through recruitment of innate immune cells and subsequent cytokine production. Finally, we provide emerging evidence of elevated circulating mitochondrial DAMPs in pre‐eclampsia.

Mitochondrial [dys]function; culprit in pre-eclampsia?

Mitochondria are extensively identified for their bioenergetic capacities; however, recently these metabolic hubs are increasingly being appreciated as critical regulators of numerous cellular signalling systems. Mitochondrial reactive oxygen species have evolved as a mode of cross-talk between mitochondrial function and physiological systems, to sustain equipoise and foster adaption to cellular stress. Redox signalling mediated by exaggerated mitochondrial-ROS (reactive oxygen species) has been incriminated in a plethora of disease pathologies. Excessive production of mitochondrial ROS is intrinsically linked to mitochondrial dysfunction. Furthermore, mitochondrial dysfunction is a key facilitator of oxidative stress, inflammation, apoptosis and metabolism. These are key pathogenic intermediaries of pre-eclampsia, hence we hypothesize that mitochondrial dysfunction is a pathogenic mediator of oxidative stress in the pathophysiology of pre-eclampsia. We hypothesize that mitochondrial-targeted antioxidants may restrain production of ROS-mediated deleterious redox signalling pathways. If our hypothesis proves correct, therapeutic strategies directly targeting mitochondrial superoxide scavenging should be actively pursued as they may alleviate maternal vascular dysfunction and dramatically improve maternal and fetal health worldwide.

SorLA modulates atheroprotective properties of CLA by regulating monocyte migration

OBJECTIVE We have previously shown that CLA induces regression of pre-established atherosclerotic lesions in apoE(-/-) mice. CLA is a known ligand of peroxisome proliferator activated receptors (PPARs) and it is postulated that CLA mediates its atheroprotective effects through activation of PPARs. Earlier work in our group identified the monocyte/macrophage cell as the primary cellular target of CLA. In this study we identified novel genes regulated by CLA during the regression of atherosclerosis and characterised a role for one of these, SorLA. SorLA is a member of the vacuolar protein sorting 10 protein (Vps10p) domain receptor family, which has structural homology with the LDLR family. METHODS AND RESULTS Expression of SorLA was identified with its Vps10p family member Sort1 by transcriptomic analysis of murine aorta following CLA-induced regression of atherosclerosis. Decreased expression of both receptors was confirmed by real-time PCR in the aorta of CLA-supplemented mice. SorLA protein expression was predominantly localised to monocyte/macrophage cells in the vasculature by immunohistochemistry. CLA and the PPAR-γ agonists, troglitazone, and 15-deoxy-prostaglandin (PG) J(2), decreased protein and RNA expression of SorLA in THP-1 monocytes; while pre-treatment with a PPAR-γ antagonist established a PPAR-γ dependent role for CLA regulation of SorLA. CLA inhibits monocyte migration. Consistent with a role for SorLA in mediating this response, overexpression of SorLA increased migration of THP-1 monocytes to monocyte chemoattractant protein-1 with a coincident increase in UPAR expression. CONCLUSION CLA may mediate its atheroprotective effects in part through reduced expression of SorLA and a resulting inhibition of monocyte migration in vitro.