Arteriolar reactivity in lymphocyte-deficient mice

Deficiency in CD4 T Cells Leads to Enhanced Postpartum Internal Carotid Artery Vasoconstriction in Mice: The Role of Nitric Oxide

The risk of postpartum (PP) stroke is increased in complicated pregnancies. Deficiency in CD4 T cell subsets is associated with preeclampsia and may contribute to PP vascular disease, including internal carotid artery (ICA) stenosis and stroke. We hypothesized that CD4 T cell deficiency in pregnancy would result in ICA dysregulation, including enhanced ICA vasoconstriction. We characterized the function, mechanical behavior, and structure of ICAs from C57BL/6 (WT) and CD4 deficient (CD4KO) mice, and assessed the role of NO in the control of ICA function at pre-conception and PP. WT and CD4KO mice were housed under pathogen-free conditions, mated to same-strain males, and allowed to litter or left virgin. At 3 days or 4 weeks PP, mice were euthanized. The responses to phenylephrine (PE), high K⁺ and acetylcholine (ACh) were assessed in pressurized ICAs before and after NOS inhibition. Passive lumen diameters were measured at 3–140 mmHg. eNOS and iNOS expression as well as the presence of T cells were evaluated by immunohistochemistry. Constriction of WT ICAs to PE was not modified PP. In contrast, responses to PE were significantly increased in ICAs from PP as compared to virgin CD4KO mice. Constriction to high K⁺ was not enhanced PP. ICAs from WT and CD4KO mice were equally sensitive to ACh with a significant rightward shift of dose-response curves after L-NNA treatment. NOS inhibition enhanced PE constriction of ICAs from WT virgin and PP mice. Although a similar effect was detected in ICAs of virgin CD4KO mice, no such changes were observed in vessels from PP CD4KO mice. Passive arterial distensibility at physiological levels of pressure was not modified at PP. ICA diameters were significantly increased in PP with no change in vascular wall thickness. Comparison of eNOS expression in virgin, 3 days and 4 weeks PP revealed a reduced expression in ICA from CD4 KO vs. WT PP vessels which reached significance at 4 weeks PP. iNos expression was similar and decreased over the PP period in vessels from WT and CD4KO mice. Dysregulation of the CD4 T cell population in pregnancy may make ICA vulnerable to vasospasm due to decreased NO-dependent control of ICA constriction. This may lead to cerebral hypoperfusion and increase the risk of maternal PP stroke.

Cholinergic modulation of the immune system - A novel therapeutic target for myocardial inflammation

The immune system and the nervous system depend on each other for their fine tuning and working, thus cooperating to maintain physiological homeostasis and prevent infections. The cholinergic system regulates the mobilization, differentiation, secretion, and antigen presentation of adaptive and innate immune cells mainly through α7 nicotinic acetylcholine receptors (α7nAChRs). The neuro-immune interactions are established and maintained by the following mechanisms: colocalization of immune and neuronal cells at defined anatomical sites, expression of the non-neuronal cholinergic system by immune cells, and the acetylcholine receptor-mediated activation of intracellular signaling pathways. Based on these immunological mechanisms, the protective effects of cholinergic system in animal models of diseases were summarized in this paper, such as myocardial infarction/ischemia-reperfusion, viral myocarditis, and endotoxin-induced myocardial damage. In addition to maintaining hemodynamic stability and improving the energy metabolism of the heart, both non-neuronal acetylcholine and neuronal acetylcholine in the heart can alleviate myocardial inflammation and remodeling to exert a significant cardioprotective effect. The new findings on the role of cholinergic agonists and vagus nerve stimulation in immune regulation are updated, so as to develop improved approaches to treat inflammatory heart disease.

The pathogenic role of coronary microvascular dysfunction in the setting of other cardiac or systemic conditions

Coronary microvascular dysfunction (CMD) plays a pathogenic role in cardiac and systemic conditions other than microvascular angina. In this review, we provide an overview of the pathogenic role of CMD in the setting of diabetes mellitus, obesity, hypertensive pregnancy disorders, chronic inflammatory and autoimmune rheumatic disorders, chronic kidney disease, hypertrophic cardiomyopathy, and aortic valve stenosis. In these various conditions, CMD results from different structural, functional, and/or dynamic alterations in the coronary microcirculation associated with the primary disease process. CMD is often detectable very early in the course of the primary disease, before clinical symptoms or signs of myocardial ischaemia are present, and it portrays an increased risk for cardiovascular events.

Immunotherapy for the rheumatoid arthritis-associated coronary artery disease: promise and future

Objective:

To review the latest progress on the pathogenic mechanism and management of rheumatoid arthritis (RA)-associated coronary artery disease (CAD), and propose advice on future management optimization as well as prospects for research and development of new therapeutic regimen.

Data sources:

This study was based on data obtained from PubMed up to May 2019 using various search terms and their combinations, including coronary artery disease, myocardial ischemia, cardiovascular diseases, RA, rheumatic diseases, treatment, therapy, strategies, immunotherapy, inflammation, and anti-inflammation.

Study selection:

All retrieved literature was scrutinized, most relevant articles about the pathogenic mechanism and clinical management, especially anti-inflammatory therapy of RA-associated CAD were reviewed.

Results:

RA is an immune-mediated chronic inflammatory disease which has a great social disease burden. In addition to typical arthritic manifestations, RA also affects extra-articular tissues and organs, within which the involvement of the cardiovascular system, especially incorporating CAD, is the leading cause of death for patients with RA. Recently, numerous basic and clinical studies have been carried out on the mechanism of CAD development and progression under the inflammatory cascade of RA. The effect of traditional RA drugs on CAD risk management has been gradually clarified, and more emerging biologic agents are being explored and studied, which have also achieved satisfactory outcomes. Furthermore, with the success of the CANTOS clinical trial, novel anti-inflammatory therapy for the prevention of cardiovascular disease is believed to have a broad prospect.

Conclusions:

RA is an independent risk factor for CAD, which mainly results from the underlying inflammatory cascade; therefore, anti-inflammatory therapy, especially the emerging novel biologic drugs, is important for CAD management in patients with RA and may also be a promising approach among the general population.

Oxygen and lack of oxygen in fetal and placental development, feto-placental coupling, and congenital heart defects

Low oxygen concentration (hypoxia) is part of normal embryonic development, yet the situation is complex. Oxygen (O₂ ) is a janus gas with low levels signaling through hypoxia-inducible transcription factor (HIF) that are required for development of fetal and placental vasculature and fetal red blood cells. This results in coupling of fetus and mother around midgestation as a functional feto-placental unit (FPU) for O₂ transport, which is required for continued growth and development of the fetus. Defects in these processes may leave the developing fetus vulnerable to O₂ deprivation or other stressors during this critical midgestational transition when common septal and conotruncal heart defects (CHDs) are likely to arise. Recent human epidemiological and case-control studies support an association between placental dysfunction, manifest as early onset pre-eclampsia (PE) and increased serum bio-markers, and CHD. Animal studies support this association, in particular those using gene inactivation in the mouse. Sophisticated methods for gene inactivation, cell fate mapping, and a quantitative bio-reporter of O₂ concentration support the premise that hypoxic stress at critical stages of development leads to CHD. The secondary heart field contributing to the cardiac outlet is a key target, with activation of the un-folded protein response and abrogation of FGF signaling or precocious activation of a cardiomyocyte transcriptional program for differentiation, suggested as mechanisms. These studies provide a strong foundation for further study of feto-placental coupling and hypoxic stress in the genesis of human CHD.

Impact of Immune Deficiency on Remodeling of Maternal Resistance Vasculature 4 Weeks Postpartum in Mice

Pregnancy manifests changes in the vascular and immune systems that persist postpartum (PP), have important implications for future pregnancies, and may modify responses to cardiovascular stress in late life. The association between immune and vascular function and the generation or progression of cardiovascular disease beg the question of whether altered immunity modifies pregnancy-induced changes in the vasculature. Our objective was to compare changes in the function and remodeling of systemic resistance vessels 4 weeks PP in normal C57BL/6 (B6), and immunodeficient mice recombinase 1-deficient/B6 ( Rag1^-/-). Immune deficiency did not change the responsiveness to acetylcholine (ACh) and phenylephrine at baseline but decreased arterial distensibility and increased stiffness PP. Adoptive transfer of CD8 T cells into Rag1^-/- mice decreased the response to ACh while increasing distensibility and wall thickness. When compared to PP Rag1^-/-, vessels from PP CD4-deficient mice, which have B cells and CD8 T cells, but no CD4 cells, show increased distensibility and decreased responsiveness to ACh in a pattern similar to that seen in Rag1^-/- given CD8 T cells prior to mating. These studies suggest a key role for T cell, particularly CD8 T cell, associated factors in the PP remodeling of maternal resistance vessels.

Potassium inhibits nitric oxide and adenosine arteriolar vasodilatation via K(IR) and Na(+)/K(+) ATPase: implications for redundancy in active hyperaemia

Redundancy, in active hyperaemia, where one vasodilator can compensate for another if the first is missing, would require that one vasodilator inhibits the effects of another; therefore, if the first vasodilator is inhibited, its inhibitory influence on the second vasodilator is removed and the second vasodilator exerts a greater vasodilatory effect. We aimed to determine whether vasodilators relevant to skeletal muscle contraction [potassium chloride (KCl), adenosine (ADO) and nitric oxide] inhibit one another and, in addition, to investigate the mechanisms for this interaction. We used the hamster cremaster muscle and intravital microscopy to directly visualize 2A arterioles when exposed to a range of concentrations of one vasodilator [10(-8) to 10(-5) M S-nitroso-N-acetyl penicillamine (SNAP), 10(-8) to 10(-5) M ADO, 10 and 20 mM KCl] in the absence and then in the presence of a second vasodilator (10(-7) M ADO, 10(-7) M SNAP, 10 mM KCl). We found that KCl significantly attenuated SNAP-induced vasodilatations by ∼65.8% and vasodilatations induced by 10(-8) to 10(-6) M ADO by ∼72.8%. Furthermore, we observed that inhibition of KCl vasodilatation, by antagonizing either Na(+)/K(+) ATPase using ouabain or inward rectifying potassium channels using barium chloride, could restore the SNAP-induced vasodilatation by up to ∼53.9% and 30.6%, respectively, and also restore the ADO-induced vasodilatations by up to ∼107% and 76.7%, respectively. Our data show that vasodilators relevant to muscle contraction can interact in a way that alters the effectiveness of other vasodilators. These data suggest that active hyperaemia may be the result of complex interactions between multiple vasodilators via a redundant control paradigm.

Leukocyte driven-decidual angiogenesis in early pregnancy

Successful pregnancy and long-term, post-natal maternal and offspring cardiac, vascular and metabolic health require key maternal cardiovascular adaptations over gestation. Within the pregnant decidualizing uterus, coordinated vascular, immunological and stromal cell changes occur. Considerable attention has been given to the roles of uterine natural killer (uNK) cells in initiating decidual spiral arterial remodeling, a process normally completed by mid-gestation in mice and in humans. However, leukocyte roles in much earlier, region specific, decidual vascular remodeling are now being defined. Interest in immune cell-promoted vascular remodeling is driven by vascular aberrations that are reported in human gestational complications such as infertility, recurrent spontaneous abortion, preeclampsia (PE) and fetal growth restriction. Appropriate maternal cardiovascular responses during pregnancy protect mothers and their children from later cardiovascular disease risk elevation. One of the earliest uterine responses to pregnancy in species with hemochorial placentation is stromal cell decidualization, which creates unique niches for angiogenesis and leukocyte recruitment. In early decidua basalis, the aspect of the implantation site that will cradle the developing placenta and provide the major blood vessels to support mature placental functions, leukocytes are greatly enriched and display specialized properties. UNK cells, the most abundant leukocyte subset in early decidua basalis, have angiogenic abilities and are essential for normal early decidual angiogenesis. The regulation of uNK cells and their roles in determining maternal and progeny cardiovascular health over pregnancy and postpartum are discussed.

Laser speckle flowmetry method for measuring spatial and temporal hemodynamic alterations throughout large microvascular networks

OBJECTIVES

1) To develop and validate laser speckle flowmetry (LSF) as a quantitative tool for individual microvessel hemodynamics in large networks. 2) To use LSF to determine if structural differences in the dorsal skinfold microcirculation (DSFWC) of C57BL/6 and BALB/c mice impart differential network hemodynamic responses to occlusion.

METHODS

We compared LSF velocity measurements with known/measured velocities in vitro using capillary tube tissue phantoms and in vivo using mouse DSFWCs and cremaster muscles. Hemodynamic changes induced by feed arteriole occlusion were measured using LSF in DSFWCs implanted on C57BL/6 and BALB/c mice.

RESULTS

In vitro, we found that the normalized speckle intensity (NSI) versus velocity linear relationship (R(2) ≥ 0.97) did not vary with diameter or hematocrit and can be shifted to meet an expected operating range. In vivo, DSFWC and cremaster muscle preparations (R(2) = 0.92 and 0.95, respectively) demonstrated similar linear relationships between NSI and centerline velocity. Stratification of arterioles into predicted collateral pathways revealed significant differences between C57BL/6 and BALB/c strains in response to feed arteriole occlusion.

CONCLUSIONS

These data demonstrate the applicability of LSF to intravital microscopy microcirculation preparations for determining both relative and absolute hemodynamics on a network-wide scale while maintaining the resolution of individual microvessels.

DBA-lectin reactivity defines mouse uterine natural killer cell subsets with biased gene expression

Endometrial decidualization, a process essential for blastocyst implantation in species with hemochorial placentation, is accompanied by an enormous but transient influx of natural killer (NK) cells. Mouse uterine NK (uNK) cell subsets have been defined by diameter and cytoplasmic granule number, reflecting stage of maturity, and by histochemical reactivity with Periodic Acid Schiff (PAS) reagent with or without co-reactivity with Dolichos biflorus agglutinin (DBA) lectin. We asked whether DBA- and DBA+ mouse uNK cells were equivalent using quantitative RT-PCR analyses of flow-separated, midpregnancy (Gestation Day [gd] 10) cells and immunohistochemistry. CD3E (CD3)-IL2RB (CD122)+DBA cells were identified as the dominant Ifng transcript source. Skewed IFNG production by uNK cell subsets was confirmed by analysis of uNK cells from eYFP-tagged IFNG-reporter mice. In contrast, CD3E-IL2RB+DBA+ uNK cells expressed genes compatible with significantly greater potential for IL22 synthesis, angiogenesis, and participation in regulation mediated by the renin-angiotensin system (RAS). CD3E-IL2RB+DBA+ cells were further divided into VEGFA+ and VEGFA- subsets. CD3E-IL2RB+DBA+ uNK cells but not CD3E-IL2RB+DBA- uNK cells arose from circulating, bone marrow-derived progenitor cells by gd6. These findings indicate the heterogeneous nature of mouse uNK cells and suggest that studies using only DBA+ uNK cells will give biased data that does not fully represent the uNK cell population.

Emerging themes in uterine natural killer cell heterogeneity and function

PROBLEM

Understanding of uterine natural killer (uNK) cell functions during normal pregnancy remains incomplete.

METHOD OF STUDY

Cloud tag analysis of literature was used to document themes addressed experimentally for uNK cells. Immunohistochemistry, including whole-mount staining of early implantation sites, separation of uNK cells into molecularly distinct subsets, and physiologic measurements in normal and mutant mice, are further advancing understanding of uNK cell biology.

RESULTS

Literature analyses revealed three key, current uNK cell research themes: angiogenesis, spiral arterial remodeling/pre-eclampsia/hypertension and infertility. UNK cells are being defined as cells potentially regulated by Wnt signaling that are heterogeneous in progenitor source and function and make unique contributions to implantation site development prior to spiral arterial remodeling.

CONCLUSION

Future studies are poised to define uNK cell progenitor cells, identify the signaling pathways supporting established uNK cell functions and move current understanding of mouse uNK cells to clinical research questions.