Expression of microRNAs is essential for arterial myogenic tone and pressure-induced activation of the PI3-kinase/Akt pathway.

The myogenic response is the intrinsic ability of small arteries to constrict in response to increased intraluminal pressure. Although microRNAs have been shown to play a role in vascular smooth muscle function, their importance in the regulation of the myogenic response is not known. In this study, we investigate the role of microRNAs in the regulation of myogenic tone by using smooth muscle-specific and tamoxifen-inducible deletion of the endonuclease Dicer in mice

Induction of angiotensin converting enzyme after miR-143/145 deletion is critical for impaired smooth muscle contractility.

MicroRNAs have emerged as regulators of smooth muscle cell phenotype with a role in smooth muscle-related disease. Studies have shown that miR-143 and miR-145 are the most highly expressed microRNAs in smooth muscle cells, controlling differentiation and function. The effect of miR-143/145 knockout has been established in the vasculature but not in smooth muscle from other organs. Using knockout mice we found that maximal contraction induced by either depolarization or phosphatase inhibition was reduced in vascular and airway smooth muscle but maintained in the urinary bladder. Furthermore, a reduction of media thickness and reduced expression of differentiation markers was seen in the aorta but not in the bladder. Supporting the view that phenotype switching depends on a tissue-specific target of miR-143/145, we found induction of angiotensin converting enzyme in the aorta but not in the bladder where angiotensin converting enzyme was expressed at a low level. Chronic treatment with angiotensin type-1 receptor antagonist restored contractility in miR-143/145-deficient aorta while leaving bladder contractility unaffected. This shows that tissue-specific targets are critical for the effects of miR-143/145 on smooth muscle differentiation and that angiotensin converting enzyme is one such target

Birth Weight, School Sports Ability, and Adulthood Leisure-Time Physical Activity

Purpose This study aimed to examine the associations of birth weight with ability in school sports in adolescence and participation in leisure-time physical activity (LTPA) across adulthood and to investigate whether associations between birth weight and LTPA change with age. Methods Study participants were British singletons born in 1946 and followed up to age 68 yr (the Medical Research Council National Survey of Health and Development). Birth weights were extracted from birth records. Teacher reports of ability in school sports were collected at age 13 yr. LTPA was self-reported at ages 36, 43, 53, 60–64, and 68 yr and categorized at each age as participating in sports, exercise, and other vigorous LTPA at least once per month versus no participation. Associations were examined using standard and mixed-effects logistic regression models. Results Relevant data were available for 2739 study participants (50.1% female). When compared with the low birth weight group (≤2.50 kg), those with heavier birth weights were more likely to be rated as above average or average at school sports (vs below average); fully adjusted odds ratio = 1.78 (95% confidence interval = 1.14–2.77). Across adulthood, those with heavier birth weights were more likely to participate in LTPA than those with low birth weight; fully adjusted odds ratio of LTPA across adulthood = 1.52 (95% confidence interval = 1.09–2.14). This association did not vary by age (P = 0.5 for birth weight by age interaction). Conclusions Low birth weight was associated with lower ability in school sports and with nonparticipation in LTPA across adulthood. Identifying the underlying developmental and social processes operating across life for low birth weight infants may inform the design of appropriate interventions to support participation in LTPA across life

Fc-Optimized Anti-CD25 Depletes Tumor-Infiltrating Regulatory T Cells and Synergizes with PD-1 Blockade to Eradicate Established Tumors

CD25 is expressed at high levels on regulatory T (Treg) cells and was initially proposed as a target for cancer immunotherapy. However, anti-CD25 antibodies have displayed limited activity against established tumors. We demonstrated that CD25 expression is largely restricted to tumor-infiltrating Treg cells in mice and humans. While existing anti-CD25 antibodies were observed to deplete Treg cells in the periphery, upregulation of the inhibitory Fc gamma receptor (FcγR) IIb at the tumor site prevented intra-tumoral Treg cell depletion, which may underlie the lack of anti-tumor activity previously observed in pre-clinical models. Use of an anti-CD25 antibody with enhanced binding to activating FcγRs led to effective depletion of tumor-infiltrating Treg cells, increased effector to Treg cell ratios, and improved control of established tumors. Combination with anti-programmed cell death protein-1 antibodies promoted complete tumor rejection, demonstrating the relevance of CD25 as a therapeutic target and promising substrate for future combination approaches in immune-oncology

Study of cellular mechanisms involved in pulmonary hypertension : role of TRP channels in the hyperactivity and the remodelling in rat pulmonary artery

L’hypertension pulmonaire (HTP) est la principale pathologie de la circulation pulmonaire et a un très mauvais pronostic. Elle se caractérise par une hyperréactivité et un remodelage des petites artères pulmonaires (AP) entraînant une augmentation progressive des résistances vasculaires pulmonaires, qui, ultimement, aboutit à une insuffisance cardiaque droite et au décès du patient. Il est admit que le calcium joue un rôle très important aussi bien dans les mécanismes de remodelage que dans l’hyperréactivité des AP observés dans l’HTP. Dans le présent travail, nous avons étudié l’expression et le rôle d’une famille particulière de canaux calciques, les TRPV, dans les AP de rats contrôles (normoxiques) et souffrant d’hypertension pulmonaire (rats hypoxiques chroniques et traités à la monocrotaline). Nous montrons que (1) les canaux TRPV1, V2 et V4 sont exprimés dans les AP et que cette expression est augmentée au cours de l’HTP ; (2) la stimulation de ces canaux par des agonistes spécifiques induit une augmentation de la concentration calcique intracellulaire dans les cellules musculaires lisses (CML) ; (3) le récepteur à la ryanodine de type 2 (RRy 2) du réticulum sarcoplasmique est impliqué dans la voie de signalisation dépendante de TRPV4 et que son expression est également augmentée au cours de l’HTP ; (4) les canaux TRPV1 et TRPV4 sont impliqués dans la migration des CML, processus fondamental du remodelage ; (5) les contractions induites par l’activation de TRPV2 et TRPV4 dans les AP de rats hypertendus sont significativement diminuées par la streptomycine, un inhibiteur des canaux SAC (stretch activated channels). Ce travail démontre donc l’implication des canaux TRPV à la fois dans l’hyperréactivté et le remodelage des AP. De nouveaux traitements ciblant les canaux TRPV pourraient constituer une approche thérapeutique innovante de l’hypertension pulmonaire.Pulmonary hypertension (PH)) is the primary pathology of the pulmonary circulation and has a very bad prognostic. This disease is characterized by a hyperreactivity and remodelling of small pulmonary arteries (PA) leading to a progressive increase in pulmonary vascular resistance which ultimately leads to right heart failure and death of the patient. It is admitted that calcium plays an important role both in the mechanisms of remodelling and in the hyperresponsiveness of PA observed in PH. In the present work, we studied the expression and the role of a particular family of calcium channels, TRPV channels, in PA from control rats (normoxic) and pulmonary hypertensive rats (chronically hypoxic and monocrotaline-treated rats). We show that (1) TRPV1, V2 and V4 channels are expressed in the PA and that their expression are increased in PH; (2) stimulation of these channels by specific agonists induces an increase in the intracellular calcium concentration in smooth muscle cells (SMC), (3) the ryanodine receptor type 2 (RRy2) of the sarcoplasmic reticulum is involved in the TRPV4-dependent signaling pathway and its expression is also increased in PH, (4) TRPV1 and TRPV4 channels are involved in the migration of SMC, the fundamental process of remodelling, (5) contractions induced by activation of TRPV2 and TRPV4 in the PA from hypertensive rats are significantly decreased by streptomycine, an inhibitor of stretch activated channels (SAC). This work thus demonstrates the involvement of TRPV channels in both the hyperreactivity and remodelling of PA. New treatments targeting TRPV channels could be an innovative therapeutic approach for pulmonary hypertension

Study of cellular mechanisms involved in pulmonary hypertension : role of TRP channels in the hyperactivity and the remodelling in rat pulmonary artery

L’hypertension pulmonaire (HTP) est la principale pathologie de la circulation pulmonaire et a un très mauvais pronostic. Elle se caractérise par une hyperréactivité et un remodelage des petites artères pulmonaires (AP) entraînant une augmentation progressive des résistances vasculaires pulmonaires, qui, ultimement, aboutit à une insuffisance cardiaque droite et au décès du patient. Il est admit que le calcium joue un rôle très important aussi bien dans les mécanismes de remodelage que dans l’hyperréactivité des AP observés dans l’HTP. Dans le présent travail, nous avons étudié l’expression et le rôle d’une famille particulière de canaux calciques, les TRPV, dans les AP de rats contrôles (normoxiques) et souffrant d’hypertension pulmonaire (rats hypoxiques chroniques et traités à la monocrotaline). Nous montrons que (1) les canaux TRPV1, V2 et V4 sont exprimés dans les AP et que cette expression est augmentée au cours de l’HTP ; (2) la stimulation de ces canaux par des agonistes spécifiques induit une augmentation de la concentration calcique intracellulaire dans les cellules musculaires lisses (CML) ; (3) le récepteur à la ryanodine de type 2 (RRy 2) du réticulum sarcoplasmique est impliqué dans la voie de signalisation dépendante de TRPV4 et que son expression est également augmentée au cours de l’HTP ; (4) les canaux TRPV1 et TRPV4 sont impliqués dans la migration des CML, processus fondamental du remodelage ; (5) les contractions induites par l’activation de TRPV2 et TRPV4 dans les AP de rats hypertendus sont significativement diminuées par la streptomycine, un inhibiteur des canaux SAC (stretch activated channels). Ce travail démontre donc l’implication des canaux TRPV à la fois dans l’hyperréactivté et le remodelage des AP. De nouveaux traitements ciblant les canaux TRPV pourraient constituer une approche thérapeutique innovante de l’hypertension pulmonaire.Pulmonary hypertension (PH)) is the primary pathology of the pulmonary circulation and has a very bad prognostic. This disease is characterized by a hyperreactivity and remodelling of small pulmonary arteries (PA) leading to a progressive increase in pulmonary vascular resistance which ultimately leads to right heart failure and death of the patient. It is admitted that calcium plays an important role both in the mechanisms of remodelling and in the hyperresponsiveness of PA observed in PH. In the present work, we studied the expression and the role of a particular family of calcium channels, TRPV channels, in PA from control rats (normoxic) and pulmonary hypertensive rats (chronically hypoxic and monocrotaline-treated rats). We show that (1) TRPV1, V2 and V4 channels are expressed in the PA and that their expression are increased in PH; (2) stimulation of these channels by specific agonists induces an increase in the intracellular calcium concentration in smooth muscle cells (SMC), (3) the ryanodine receptor type 2 (RRy2) of the sarcoplasmic reticulum is involved in the TRPV4-dependent signaling pathway and its expression is also increased in PH, (4) TRPV1 and TRPV4 channels are involved in the migration of SMC, the fundamental process of remodelling, (5) contractions induced by activation of TRPV2 and TRPV4 in the PA from hypertensive rats are significantly decreased by streptomycine, an inhibitor of stretch activated channels (SAC). This work thus demonstrates the involvement of TRPV channels in both the hyperreactivity and remodelling of PA. New treatments targeting TRPV channels could be an innovative therapeutic approach for pulmonary hypertension

Role of the gap junctions in the contractile response to agonists in pulmonary artery from two rat models of pulmonary hypertension

Background Pulmonary hypertension (PH) is characterized by arterial vascular remodelling and alteration in vascular reactivity. Since gap junctions are formed with proteins named connexins (Cx) and contribute to vasoreactivity, we investigated both expression and role of Cx in the pulmonary arterial vasoreactivity in two rat models of PH. Methods Intrapulmonary arteries (IPA) were isolated from normoxic rats (N), rats exposed to chronic hypoxia (CH) or treated with monocrotaline (MCT). RT-PCR, Western Blot and immunofluorescent labelling were used to study the Cx expression. The role of Cx in arterial reactivity was assessed by using isometric contraction and specific gap junction blockers. Contractile responses were induced by agonists already known to be involved in PH, namely serotonin, endothelin-1 and phenylephrine. Results Cx 37, 40 and 43 were expressed in all rat models and Cx43 was increased in CH rats. In IPA from N rats only, the contraction to serotonin was decreased after treatment with 37-43Gap27, a specific Cx-mimetic peptide blocker of Cx 37 and 43. The contraction to endothelin-1 was unchanged after incubation with 40Gap27 (a specific blocker of Cx 40) or 37-43Gap27 in N, CH and MCT rats. In contrast, the contraction to phenylephrine was decreased by 40Gap27 or 37-43Gap27 in CH and MCT rats. Moreover, the contractile sensitivity to high potassium solutions was increased in CH rats and this hypersensitivity was reversed following 37-43Gap27 incubation. Conclusion Altogether, Cx 37, 40 and 43 are differently expressed and involved in the vasoreactivity to various stimuli in IPA from different rat models. These data may help to understand alterations of pulmonary arterial reactivity observed in PH and to improve the development of innovative therapies according to PH aetiology.</p

Mir-29 repression in bladder outlet obstruction contributes to matrix remodeling and altered stiffness.

Recent work has uncovered a role of the microRNA (miRNA) miR-29 in remodeling of the extracellular matrix. Partial bladder outlet obstruction is a prevalent condition in older men with prostate enlargement that leads to matrix synthesis in the lower urinary tract and increases bladder stiffness. Here we tested the hypothesis that miR-29 is repressed in the bladder in outlet obstruction and that this has an impact on protein synthesis and matrix remodeling leading to increased bladder stiffness. c-Myc, NF-κB and SMAD3, all of which repress miR-29, were activated in the rat detrusor following partial bladder outlet obstruction but at different times. c-Myc and NF-κB activation occurred early after obstruction, and SMAD3 phosphorylation increased later, with a significant elevation at 6 weeks. c-Myc, NF-κB and SMAD3 activation, respectively, correlated with repression of miR-29b and miR-29c at 10 days of obstruction and with repression of miR-29c at 6 weeks. An mRNA microarray analysis showed that the reduction of miR-29 following outlet obstruction was associated with increased levels of miR-29 target mRNAs, including mRNAs for tropoelastin, the matricellular protein Sparc and collagen IV. Outlet obstruction increased protein levels of eight out of eight examined miR-29 targets, including tropoelastin and Sparc. Transfection of human bladder smooth muscle cells with antimiR-29c and miR-29c mimic caused reciprocal changes in target protein levels in vitro. Tamoxifen inducible and smooth muscle-specific deletion of Dicer in mice reduced miR-29 expression and increased tropoelastin and the thickness of the basal lamina surrounding smooth muscle cells in the bladder. It also increased detrusor stiffness independent of outlet obstruction. Taken together, our study supports a model where the combined repressive influences of c-Myc, NF-κB and SMAD3 reduce miR-29 in bladder outlet obstruction, and where the resulting drop in miR-29 contributes to matrix remodeling and altered passive mechanical properties of the detrusor

Spontaneous activity and stretch-induced contractile differentiation are reduced in vascular smooth muscle of miR-143/145 knockout mice.

Stretch is essential for maintaining the contractile phenotype of vascular smooth muscle cells, and small non-coding microRNAs are known to be important in this process. Using a Dicer knockout model, we have previously reported that microRNAs are essential for stretch-induced differentiation and regulation of L-type calcium channel expression. The aim of this study was to investigate the importance of the smooth muscle-enriched miR-143/145 microRNA cluster for stretch-induced differentiation of the portal vein