Mineralocorticoid receptor signaling reduces numbers of circulating human naïve T cells and increases their CD62L, CCR7, and CXCR4 expression

Sleep promotes T-cell migration towards CCL19 via growth hormone and prolactin signaling in humans

Sleep strongly supports the formation of adaptive immunity, e.g., after vaccination. However, the underlying mechanisms remain largely obscure. Here we show in healthy humans that sleep compared to nocturnal wakefulness specifically promotes the migration of various T-cell subsets towards the chemokine CCL19, which is essential for lymph-node homing and, thus, for the initiation and maintenance of adaptive immune responses. Migration towards the inflammatory chemokine CCL5 remained unaffected. Incubating the cells with plasma from sleeping participants likewise increased CCL19-directed migration, an effect that was dependent on growth hormone and prolactin signaling. These findings show that sleep selectively promotes the lymph node homing potential of T cells by increasing hormonal release, and thus reveal a causal mechanism underlying the supporting effect of sleep on adaptive immunity in humans.

Several first-line anti-hypertensives act on fibrosarcoma progression and PD1ab blockade therapy

PURPOSE

Patients are typically diagnosed with both hypertension and fibrosarcoma. Medical oncologists must prescribe suitable anti-hypertensive medications while considering anti-tumor drugs. Recently, immunotherapy has become prominent in cancer treatment. Nonetheless, it is unknown what role anti-hypertensive medications will play in immunotherapy.

METHODS

We examined the effects of six first-line anti-hypertensive medications on programmed cell death protein 1 antibody (PD1ab) in tumor treatment using a mouse model of subcutaneous fibrosarcoma. The drugs examined were verapamil, losartan, furosemide, spironolactone, captopril, and hydrochlorothiazide (HCTZ). The infiltration of CD8+ T cells was examined by immunohistochemistry. Additionally, several in vitro and in vivo assays were used to study the effects of HCTZ on human fibrosarcoma cancer cells to explore its mechanism.

RESULTS

Verapamil suppressed tumor growth and showed an improved effect on the tumor inhibition of PD1ab. Captopril did not affect tumor growth but brought an unexpected benefit to PD1ab treatment. In contrast, spironolactone and furosemide showed no effect on tumor growth but had an offset effect on the PD1ab therapy. Consequently, the survival time of mice was also significantly reduced. Notably, losartan and HCTZ, especially HCTZ, promoted tumor growth and weakened the effect of PD1ab treatment. Consistent results were observed in vivo and in vitro using the human fibrosarcoma cell line HT1080. We determined that the Solute Carrier Family 12 Member 3 (SLC12A3), a known target of HCTZ, may be the principal factor underlying its effect-enhancing properties through mechanism studies employing The Cancer Genome Atlas (TCGA) data and in vivo and in vitro assays.

CONCLUSION

Verapamil and captopril potentiated the anti-tumor effect of PD1ab, whereas spironolactone and furosemide weakened the effect of PD1ab on tumor inhibition. Alarmingly, losartan and HCTZ promoted tumor growth and impaired the effect of PD1ab. Furthermore, we preliminarily found that HCTZ may promote tumor progression through SLC12A3. Based on this study, futher mechanism researches and clinical trials should be conducted in the future.

Caloric restriction for the immunometabolic control of human health

Nutrition affects all physiological processes occurring in our body, including those related to the function of the immune system; indeed, metabolism has been closely associated with the differentiation and activity of both innate and adaptive immune cells. While excessive energy intake and adiposity have been demonstrated to cause systemic inflammation, several clinical and experimental evidence show that calorie restriction (CR), not leading to malnutrition, is able to delay aging and exert potent anti-inflammatory effects in different pathological conditions. This review provides an overview of the ability of different CR-related nutritional strategies to control autoimmune, cardiovascular, and infectious diseases, as tested by preclinical studies and human clinical trials, with a specific focus on the immunological aspects of these interventions. In particular, we recapitulate the state of the art on the cellular and molecular mechanisms pertaining to immune cell metabolic rewiring, regulatory T cell expansion, and gut microbiota composition, which possibly underline the beneficial effects of CR. Although studies are still needed to fully evaluate the feasibility and efficacy of the nutritional intervention in clinical practice, the experimental observations discussed here suggest a relevant role of CR in lowering the inflammatory state in a plethora of different pathologies, thus representing a promising therapeutic strategy for the control of human health.

Immunomodulation and immunopharmacology in heart failure

The immune system is intimately involved in the pathophysiology of heart failure. However, it is currently underused as a therapeutic target in the clinical setting. Moreover, the development of novel immunomodulatory therapies and their investigation for the treatment of patients with heart failure are hampered by the fact that currently used, evidence-based treatments for heart failure exert multiple immunomodulatory effects. In this Review, we discuss current knowledge on how evidence-based treatments for heart failure affect the immune system in addition to their primary mechanism of action, both to inform practising physicians about these pleiotropic actions and to create a framework for the development and application of future immunomodulatory therapies. We also delineate which subpopulations of patients with heart failure might benefit from immunomodulatory treatments. Furthermore, we summarize completed and ongoing clinical trials that assess immunomodulatory treatments in heart failure and present several therapeutic targets that could be investigated in the future. Lastly, we provide future directions to leverage the immunomodulatory potential of existing treatments and to foster the investigation of novel immunomodulatory therapeutics.

Shorter total sleep time is associated with lower CD4+/CD8+ T cell ratios in virally suppressed men with HIV

Study Objectives

Although poor sleep quality is associated with lower CD4+ T cell counts among people living with HIV (PLWH), the association between objective sleep metrics and T lymphocyte subset counts is unknown. We evaluated the association between polysomnography (PSG) derived sleep metrics and T lymphocyte subpopulations in a cohort of men living with HIV.

Methods

Virally suppressed men living with HIV participating in the Multicenter AIDS Cohort Study underwent home overnight PSG. We assessed the association of PSG parameters with CD4+ and CD8+ T cell counts and the CD4+/CD8+ T cell ratio.

Results

Overall, 289 men with mean (±SD) age 55.3 ± 11.3 years and mean CD4+ T cell count 730 ± 308 cells/mm3 were evaluated. Total sleep time (TST) was significantly associated with CD8+ but not CD4+ T cell counts. After adjusting for age, race, depressive symptoms, antidepressant use, and non-nucleoside reverse transcriptase inhibitors use, every hour of shorter TST was associated with an additional 33 circulating CD8+ T cells/mm3 (p = 0.05) and a 5.6% (p = 0.0007) decline in CD4+/CD8+ T cell ratio. In adjusted models, every hour of shorter rapid eye movement (REM) sleep was associated with an additional 113 CD8+ T cells/mm3 (p = 0.02) and a 15.1% lower CD4+/CD8+ T cell ratio (p = 0.006). In contrast, measures of sleep efficiency and sleep-disordered breathing were not associated with differences in T lymphocyte subpopulations.

Conclusions

Our findings suggest that shorter TST and REM sleep durations are associated with differences in T lymphocyte subpopulations among men living with HIV. Addressing sleep may reflect a novel opportunity to improve immune function in PLWH.

Risk Factors for Surgical Site Infections After Single-Level Anterior Lumbar Interbody Fusion

Abstract Background: Anterior lumbar interbody fusion (ALIF) has become an increasingly popular and effective treatment modality for various conditions of the lumbar spine. However, complications after this procedure can be costly. Surgical site infections (SSIs) are one of these types of complications. The present study identifies independent risk factors for SSI after single-level ALIF to identify high-risk patients better. Patients and Methods: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was queried to identify single-level ALIF patients from 2005 to 2016. Multilevel fusions and non-anterior approach procedures were excluded. Mann-Pearson χ² tests analyzed categorical variables, whereas one-way analysis of variance (ANOVA) and independent t-tests analyzed differences in mean values of continuous variables. Risk factors for SSI were identified via a multivariable logistic regression model. A receiver operating characteristic (ROC) curve was generated utilizing the predicted probabilities. Results: A total of 10,017 patients met inclusion criteria; 80 (0.80%) had developed SSI and 9,937 (99.20%) had not. On multivariable logistic regression models, class 3 obesity (p = 0.014), dialysis (p = 0.025), long-term steroid use (p = 0.010), and wound classification 4 (dirty/infected) (p = 0.002) all independently increased the risk for SSI in single-level ALIF. The area under the receiver operating characteristic curve (AUROC; C-statistic) was 0.728 (p < 0.001), indicating relatively strong reliability of the final model. Conclusions: Several independent risk factors including obesity, dialysis, long-term steroid use, and dirty wound classification all increased risk for SSI after single-level ALIF. By identifying these high-risk patients, surgeons and patients can have more informed pre-operative discussions. In addition, identifying and optimizing these patients prior to operative intervention may help to minimize infection risk.

The contribution of sleep to the neuroendocrine regulation of rhythms in human leukocyte traffic

Twenty-four-hour rhythms in immune parameters and functions are robustly observed phenomena in biomedicine. Here, we summarize the important role of sleep and associated parameters on the neuroendocrine regulation of rhythmic immune cell traffic to different compartments, with a focus on human leukocyte subsets. Blood counts of "stress leukocytes" such as neutrophils, natural killer cells, and highly differentiated cytotoxic T cells present a rhythm with a daytime peak. It is mediated by morning increases in epinephrine, leading to a mobilization of these cells out of the marginal pool into the circulation following a fast, beta2-adrenoceptor-dependent inhibition of adhesive integrin signaling. In contrast, other subsets such as eosinophils and less differentiated T cells are redirected out of the circulation during daytime. This is mediated by stimulation of the glucocorticoid receptor following morning increases in cortisol, which promotes CXCR4-driven leukocyte traffic, presumably to the bone marrow. Hence, these cells show highest numbers in blood at night when cortisol levels are lowest. Sleep adds to these rhythms by actively suppressing epinephrine and cortisol levels. In addition, sleep increases levels of immunosupportive mediators, such as aldosterone and growth hormone, which are assumed to promote T-cell homing to lymph nodes, thus facilitating the initiation of adaptive immune responses during sleep. Taken together, sleep-wake behavior with its unique neuroendocrine changes regulates human leukocyte traffic with overall immunosupportive effects during nocturnal sleep. In contrast, integrin de-activation and redistribution of certain leukocytes to the bone marrow during daytime activity presumably serves immune regulation and homeostasis.

Prolonged high-intensity exercise induces fluctuating immune responses to herpes simplex virus infection via glucocorticoids

BACKGROUND

Epidemiologic studies have yielded conflicting results regarding the influence of a single bout of prolonged high-intensity exercise on viral infection.

OBJECTIVE

We sought to learn whether prolonged high-intensity exercise either exacerbates or ameliorates herpes simplex virus type 2 (HSV-2) infection according to the interval between virus exposure and exercise.

METHODS

Mice were intravaginally infected with HSV-2 and exposed to run on the treadmill.

RESULTS

Prolonged high-intensity exercise 17 hours after infection impaired the clearance of HSV-2, while exercise 8 hours after infection enhanced the clearance of HSV-2. These impaired or enhanced immune responses were related to a transient decrease or increase in the number of blood-circulating plasmacytoid dendritic cells. Exercise-induced glucocorticoids transiently decreased the number of circulating plasmacytoid dendritic cells by facilitating their homing to the bone marrow via the CXCL12-CXCR4 axis, which led to their subsequent increase in the blood.

CONCLUSION

A single bout of prolonged high-intensity exercise can be either deleterious or beneficial to antiviral immunity.

Increased Rates of Septic Shock, Cardiac Arrest, and Mortality Associated With Chronic Steroid Use Following Anterior Cervical Discectomy and Fusion for Cervical Stenosis

OBJECTIVE

Anterior cervical discectomy and fusion (ACDF) is an established treatment modality for cervical spondylosis. Many patients are on immunosuppressant therapy in the management of various inflammatory spinal pathologies and other comorbid conditions. The impact of chronic steroid use on postoperative complications has not been examined in cervical fusion procedures. The objective of this study was to identify specific postoperative complications associated with steroid/immunosuppressant use following ACDF for cervical stenosis.

METHODS

A multi-institutional surgical registry was queried to identify 5377 patients with ACDF diagnosed with cervical stenosis. Patients were stratified into cohorts with a history of steroid/immunosuppressant use for chronic conditions (n = 198, 3.3%) versus those who did not (n = 5179, 96.7%). Propensity-score matching without replacement was implemented to control for preoperative demographics and comorbidities. Pearson χ² and Fischer exact tests were used in comparing the prevalence of demographics, comorbidities, and complication rates.

RESULTS

Upon propensity matching, increased rates of pulmonary embolisms (0.51% vs 0.00%, P = .025), cardiac arrest requiring resuscitation (1.01% vs 0.10%, P = .020), septic shock (0.51% vs 0.00%, P = .025), and mortality (1.52% vs 0.20%, P = .009) in the postoperative 30-day period in patients on chronic steroid/immunosuppressant use were observed.

CONCLUSIONS

The results indicate that steroid use/immunosuppression in patients with ACDF has a higher associated rate of pulmonary embolisms, cardiac arrest, septic shock, and mortality. The risk of mortality and these other complications should be carefully considered prior to operative intervention. Future research may investigate steroid-tapering protocols that reduce the rate of infection and other postoperative complications in the subset of immunosuppressed ACDF patients.

CLINICAL RELEVANCE

By elucidating the complication rates of ACDF patients on steroids for cervical stenosis, orthopedic surgeons can better stratify patients for risk of postoperative morbidity. Surgeons may have deeper risk-benefit discussions with these specific patients before they elect to have the operation.

Regulation of the germinal center response by nuclear receptors and implications for autoimmune diseases

The immune system plays an essential role in protecting the host from infectious diseases and cancer. Notably, B and T lymphocytes from the adaptive arm of the immune system can co-operate to form long-lived antibody responses and are therefore the main target in vaccination approaches. Nevertheless, protective immune responses must be tightly regulated to avoid hyper-responsiveness and responses against self that can result in autoimmunity. Nuclear receptors (NRs) are perfectly adapted to rapidly alter transcriptional cellular responses to altered environmental settings. Their functional role is associated with both immune deficiencies and autoimmunity. Despite extensive linking of nuclear receptor function with specific CD4 T helper subsets, research on the functional roles and mechanisms of specific NRs in CD4 follicular T helper cells (Tfh) and germinal center (GC) B cells during the germinal center reaction is just emerging. We review recent advances in our understanding of NR regulation in specific cell types of the GC response and discuss their implications for autoimmune diseases such as systemic lupus erythematosus (SLE).

Effect of acute and chronic aldosterone exposure on the retinal pigment epithelium-choroid complex in rodents

Preclinical and clinical evidences show that aldosterone and/or mineralocorticoid receptor (MR) over-activation by glucocorticoids can be deleterious to the retina and to the retinal pigment epithelium (RPE)-choroid complex. However, the exact molecular mechanisms driving these effects remain poorly understood and pathological consequences of chronic exposure of the retina and RPE/choroid to aldosterone have not been completely explored. We aimed to decipher the transcriptomic regulation in the RPE-choroid complex in rats in response to acute intraocular aldosterone injection and to explore the consequences of systemic chronic aldosterone exposure on the morphology and the gene regulation in RPE/choroid in mice. High dose of aldosterone (100 nM) was intravitreously injected in Lewis rat eyes in order to yield an aldosterone dose able to induce a molecular response at the apical side of the RPE-choroid complex. The posterior segment morphology was evaluated in vivo using optical coherence tomography (OCT) before and 24 h after aldosterone injection. Rat RPE-choroid complexes were used for RNA sequencing and analysis. Uninephrectomy/aldosterone/salt (NAS) model was created in wild-type C57BL/6 mice. After 6 weeks, histology of mouse posterior segments were observed ex vivo. Gene expression in the RPE-choroid complex was analyzed using quantitative PCR. Acute intravitreous injection of aldosterone induced posterior segment inflammation observed on OCT. RNA sequencing of rat RPE-choroid complexes revealed up-regulation of pathways involved in inflammation, oxidative stress and RNA procession, and down-regulation of genes involved in synaptic activity, muscle contraction, cytoskeleton, cell junction and transporters. Chronic aldosterone/salt exposure in NAS model induces retinal edema, choroidal vasodilation and RPE cell dysfunction and migration. Quantitative PCR showed deregulation of genes involved in inflammatory response, oxidative stress, particularly the NOX pathway, angiogenesis and cell contractility. Both rodent models share some common phenotypes and molecular regulations in the RPE-choroid complex that could contribute to pachychoroid epitheliopathy in humans. The difference in inflammatory status relies on different intraocular or systemic route of aldosterone administration and on the different doses of aldosterone exposed to the RPE-choroid complex.

The Sleep-Immune Crosstalk in Health and Disease

Sleep and immunity are bidirectionally linked. Immune system activation alters sleep, and sleep in turn affects the innate and adaptive arm of our body's defense system. Stimulation of the immune system by microbial challenges triggers an inflammatory response, which, depending on its magnitude and time course, can induce an increase in sleep duration and intensity, but also a disruption of sleep. Enhancement of sleep during an infection is assumed to feedback to the immune system to promote host defense. Indeed, sleep affects various immune parameters, is associated with a reduced infection risk, and can improve infection outcome and vaccination responses. The induction of a hormonal constellation that supports immune functions is one likely mechanism underlying the immune-supporting effects of sleep. In the absence of an infectious challenge, sleep appears to promote inflammatory homeostasis through effects on several inflammatory mediators, such as cytokines. This notion is supported by findings that prolonged sleep deficiency (e.g., short sleep duration, sleep disturbance) can lead to chronic, systemic low-grade inflammation and is associated with various diseases that have an inflammatory component, like diabetes, atherosclerosis, and neurodegeneration. Here, we review available data on this regulatory sleep-immune crosstalk, point out methodological challenges, and suggest questions open for future research.

Control of Leukocyte Trafficking by Stress-Associated Hormones

Leukocyte migration is a crucial process in both homeostatic and inflammatory conditions. The spatiotemporal distribution of immune cells is balanced between processes of cellular mobilization into the bloodstream, their adhesion to vascular beds and trafficking into tissues. Systemic regulation of leukocyte mobility is achieved by different signals including neuronal and hormonal cues, of which the catecholamines and glucocorticoids have been most extensively studied. These hormones are often associated with a stress response, however they regulate immune cell trafficking also in steady state, with effects dependent upon cell type, location, time-of-day, concentration, and duration of signal. Systemic administration of catecholamines, such as the sympathetic neurotransmitters adrenaline and noradrenaline, increases neutrophil numbers in the bloodstream but has different effects on other leukocyte populations. In contrast, local, endogenous sympathetic tone has been shown to be crucial for dynamic daily changes in adhesion molecule expression in the bone marrow and skeletal muscle, acting as a key signal to the endothelium and stromal cells to regulate immune cell trafficking. Conversely, glucocorticoids are often reported as anti-inflammatory, although recent data shows a more complex role, particularly under steady-state conditions. Endogenous changes in circulating glucocorticoid concentration induce redistribution of cells and potentiate inflammatory responses, and in many paradigms glucocorticoid action is strongly influenced by time of day. In this review, we discuss the current knowledge of catecholamine and glucocorticoid regulation of leukocyte migration under homeostatic and stimulated conditions.

Mineralocorticoid Receptor and Aldosterone-Related Biomarkers of End-Organ Damage in Cardiometabolic Disease

The mineralocorticoid receptor (MR) was first identified as a blood pressure regulator, modulating renal sodium handling in response to its principal ligand aldosterone. The mineralocorticoid receptor is also expressed in many tissues other than the kidney, such as adipose tissue, heart and vasculature. Recent studies have shown that MR plays a relevant role in the control of cardiovascular and metabolic function, as well as in adipogenesis. Dysregulation of aldosterone/MR signaling represents an important cause of disease as high plasma levels of aldosterone are associated with hypertension, obesity and increased cardiovascular risk. Aldosterone displays powerful vascular effects and acts as a potent pro-fibrotic agent in cardiovascular remodeling. Mineralocorticoid receptor activation regulates genes involved in vascular and cardiac fibrosis, calcification and inflammation. This review focuses on the role of novel potential biomarkers related to aldosterone/MR system that could help identify cardiovascular and metabolic detrimental conditions, as a result of altered MR activation. Specifically, we discuss: (1) how MR signaling regulates the number and function of different subpopulations of circulating and intra-tissue immune cells; (2) the role of aldosterone/MR system in mediating cardiometabolic diseases induced by obesity; and (3) the role of several MR downstream molecules as novel potential biomarkers of cardiometabolic diseases, end-organ damage and rehabilitation outcome.

Auditory closed-loop stimulation of EEG slow oscillations strengthens sleep and signs of its immune-supportive function

Sleep is essential for health. Slow wave sleep (SWS), the deepest sleep stage hallmarked by electroencephalographic slow oscillations (SOs), appears of particular relevance here. SWS is associated with a unique endocrine milieu comprising minimum cortisol and high aldosterone, growth hormone (GH), and prolactin levels, thereby presumably fostering efficient adaptive immune responses. Yet, whether SWS causes these changes is unclear. Here we enhance SOs in men by auditory closed-loop stimulation, i.e., by delivering tones in synchrony with endogenous SOs. Stimulation intensifies the hormonal milieu characterizing SWS (mainly by further reducing cortisol and increasing aldosterone levels) and reduces T and B cell counts, likely reflecting a redistribution of these cells to lymphoid tissues. GH remains unchanged. In conclusion, closed-loop stimulation of SOs is an easy-to-use tool for probing SWS functions, and might also bear the potential to ameliorate conditions like depression and aging, where disturbed sleep coalesces with specific hormonal and immunological dysregulations.

Circulating hormones undergo fluctuations during sleep. Here, the authors increase electroencephalographic slow oscillations (SO) during sleep in men using an auditory closed-loop stimulation, and show that the circulating level of cortisol, aldosterone and immune cell count can be altered.

Mineralocorticoid Receptor Deficiency in T Cells Attenuates Pressure Overload-Induced Cardiac Hypertrophy and Dysfunction Through Modulating T-Cell Activation

Although antagonists of mineralocorticoid receptor (MR) have been widely used to treat heart failure, the underlying mechanisms are incompletely understood. Recent reports show that T cells play important roles in pathologic cardiac hypertrophy and heart failure. However, it is unclear whether and how MR functions in T cells under these pathologic conditions. We found that MR antagonist suppressed abdominal aortic constriction-induced cardiac hypertrophy and decreased the accumulation and activation of CD4⁺ and CD8⁺ T cells in mouse heart. T-cell MR knockout mice manifested suppressed cardiac hypertrophy, fibrosis, and dysfunction compared with littermate control mice after abdominal aortic constriction. T-cell MR knockout mice had less cardiac inflammatory response, which was illustrated by decreased accumulation of myeloid cells and reduced expression of inflammatory cytokines. Less amounts and activation of T cells were observed in the heart of T-cell MR knockout mice after abdominal aortic constriction. In vitro studies showed that both MR antagonism and deficiency repressed activation of T cells, whereas MR overexpression elevated activation of T cells. These results demonstrated that MR blockade in T cells protected against abdominal aortic constriction-induced cardiac hypertrophy and dysfunction. Mechanistically, MR directly regulated T-cell activation and modulated cardiac inflammation. Targeting MR in T cells specifically may be a feasible strategy for more effective treatment of pathologic cardiac hypertrophy and heart failure.

Nocturnal sleep uniformly reduces numbers of different T-cell subsets in the blood of healthy men

In humans, numbers of circulating T cells show a circadian rhythm with peak counts during the night and a steep decline in the morning. Sleep per se appears to counter this rhythm by acutely reducing the total number of T cells. The T-cell population, however, is rather heterogeneous, comprising various subpopulations with different features and functions and also different circadian rhythms. Therefore, we examined here whether sleep likewise differentially affects these subsets. We measured eight different T-cell subsets (naïve, central memory, effector memory, and effector CD4+ and CD8+ T cells) over a 24-h period under conditions of sustained wakefulness compared with a regular sleep-wake cycle in 14 healthy young men. Sleep reduced the number of all T-cell subsets during nighttime with this effect reaching the P < 0.05 level of significance in all but one subpopulation, i.e., effector CD4+ T cells, where it only approached significance. Furthermore, sleep was associated with an increase in growth hormone, prolactin, and aldosterone levels, whereas concentrations of catecholamines tended to be lower than during nocturnal wakefulness. The effect of sleep uniformly decreasing the different T-cell subsets is surprising considering their differential function and circadian rhythms, and even more so, since the sleep-induced decreases in these subsets are probably conveyed by different hormonal mediators. Although the reductions in cell numbers are rather small, they are comparable to changes seen, for example, after vaccination and are, therefore, likely to be of physiological relevance.

Mechanisms of T cell organotropism

Protective immunity relies upon T cell differentiation and subsequent migration to target tissues. Similarly, immune homeostasis requires the localization of regulatory T cells (Tregs) to the sites where immunity takes place. While naïve T lymphocytes recirculate predominantly in secondary lymphoid tissue, primed T cells and activated Tregs must traffic to the antigen rich non-lymphoid tissue to exert effector and regulatory responses, respectively. Following priming in draining lymph nodes, T cells acquire the 'homing receptors' to facilitate their access to specific tissues and organs. An additional level of topographic specificity is provided by T cells receptor recognition of antigen displayed by the endothelium. Furthermore, co-stimulatory signals (such as those induced by CD28) have been shown not only to regulate T cell activation and differentiation, but also to orchestrate the anatomy of the ensuing T cell response. We here review the molecular mechanisms supporting trafficking of both effector and regulatory T cells to specific antigen-rich tissues.

Distribution and Abundance of Glucocorticoid and Mineralocorticoid Receptors throughout the Brain of the Great Tit (Parus major)

The glucocorticoid stress response, regulated by the hypothalamic-pituitary-adrenal (HPA) axis, enables individuals to cope with stressors through transcriptional effects in cells expressing the appropriate receptors. The two receptors that bind glucocorticoids—the mineralocorticoid receptor (MR) and glucocorticoid receptor (GR)—are present in a variety of vertebrate tissues, but their expression in the brain is especially important. Neural receptor patterns have the potential to integrate multiple behavioral and physiological traits simultaneously, including self-regulation of glucocorticoid secretion through negative feedback processes. In the present work, we quantified the expression of GR and MR mRNA throughout the brain of a female great tit (Parus major), creating a distribution map encompassing 48 regions. This map, the first of its kind for P. major, demonstrated a widespread but not ubiquitous distribution of both receptor types. In the paraventricular nucleus of the hypothalamus (PVN) and the hippocampus (HP)—the two brain regions that we sampled from a total of 25 birds, we found high GR mRNA expression in the former and, unexpectedly, low MR mRNA in the latter. We examined the covariation of MR and GR levels in these two regions and found a strong, positive relationship between MR in the PVN and MR in the HP and a similar trend for GR across these two regions. This correlation supports the idea that hormone pleiotropy may constrain an individual’s behavioral and physiological phenotype. In the female song system, we found moderate GR in hyperstriatum ventrale, pars caudalis (HVC), and moderate MR in robust nucleus of the arcopallium (RA). Understanding intra- and interspecific patterns of glucocorticoid receptor expression can inform us about the behavioral processes (e.g. song learning) that may be sensitive to stress and stimulate future hypotheses concerning the relationships between receptor expression, circulating hormone concentrations and performance traits under selection, including behavior.

Renin-angiotensin system contributes to naive T-cell migration in vivo

Angiotensin II (Ang II) plays an important role in the regulation of the T-cell response during inflammation. However, the cellular mechanisms underlying the regulation of lymphocytes under physiologic conditions have not yet been studied. Here, we tested the influence of Ang II on T-cell migration using T cells from BALB/c mice. The results obtained in vivo showed that when Ang II production or the AT1 receptor were blocked, T-cell counts were enhanced in blood but decreased in the spleen. The significance of these effects was confirmed by observing that these cells migrate, through fibronectin to Ang II via the AT1 receptor. We also observed a gradient of Ang II from peripheral blood to the spleen, which explains its chemotactic effect on this organ. The following cellular mechanisms were identified to mediate the Ang II effect: upregulation of the chemokine receptor CCR9; upregulation of the adhesion molecule CD62L; increased production of the chemokines CCL19 and CCL25 in the spleen. These results indicate that the higher levels of Ang II in the spleen and AT1 receptor activation contribute to migration of naive T cells to the spleen, which expands our understanding on how the Ang II/AT1 receptor axis contributes to adaptive immunity.

Mineralocorticoid Receptors in the Pathophysiology of Vascular Inflammation and Atherosclerosis

Atherosclerosis is a chronic inflammatory disease of the vasculature that causes significant morbidity and mortality from myocardial infarction, stroke, and peripheral vascular disease. Landmark clinical trials revealed that mineralocorticoid receptor (MR) antagonists improve outcomes in cardiovascular patients. Conversely, enhanced MR activation by the hormone aldosterone is associated with increased risk of MI, stroke, and cardiovascular death. This review summarizes recent advances in our understanding of the role of aldosterone and the MR in the pathogenesis of vascular inflammation and atherosclerosis as it proceeds from risk factor-induced endothelial dysfunction and inflammation to plaque formation, progression, and ultimately rupture with thrombosis, the cause of acute ischemia. The role of the MR in converting cardiac risk factors into endothelial dysfunction, in enhancing leukocyte adhesion and infiltration into the vasculature, in promoting systemic inflammation and vascular oxidative stress, and in plaque destabilization and thrombosis are discussed. A greater understanding of the mechanisms by which the MR promotes atherosclerosis has substantial potential to identify novel treatment targets to improve cardiovascular health and decrease mortality.

Mineralocorticoid receptor: a critical player in vascular remodeling

Vascular remodeling is a pathological condition with structural changes of blood vessels. Both inside-out and outside-in hypothesis have been put forward to describe mechanisms of vascular remodeling. An integrated model of these two hypotheses emphasizes the importance of immune cells such as monocytes/macrophages, T cells, and dendritic cells. These immune cells are at the center stage to orchestrate cellular proliferation, migration, and interactions of themselves and other vascular cells including endothelial cells (ECs), vascular smooth muscle cells (VSMCs), and fibroblasts. These changes on vascular wall lead to inflammation and oxidative stress that are largely responsible for vascular remodeling. Mineralocorticoid receptor (MR) is a classic nuclear receptor. MR agonist promotes inflammation and oxidative stress and therefore exacerbates vascular remodeling. Conversely, MR antagonists have the opposite effects. MR has direct roles on vascular cells through non-genomic or genomic actions to modulate inflammation and oxidative stress. Recent studies using genetic mouse models have revealed that MR in myeloid cells, VSMCs and ECs all contribute to vascular remodeling. In conclusion, data in the past years have demonstrated that MR is a critical control point in modulating vascular remodeling. Studies will continue to provide evidence with more detailed mechanisms to support this notion.