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Sympathetic ?1-adrenergic signaling contributes to regulation of human bone metabolism.

ABSTRACT: BACKGROUND:Evidence from rodent studies indicates that the sympathetic nervous system (SNS) regulates bone metabolism, principally via ?2-adrenergic receptors (?2-ARs). Given the conflicting human data, we used multiple approaches to evaluate the role of the SNS in regulating human bone metabolism. METHODS:Bone biopsies were obtained from 19 young and 19 elderly women for assessment of ADRB1, ADRB2, and ADRB3 mRNA expression. We examined the relationship of ?-blocker use to bone microarchitecture by high-resolution peripheral quantitative CT in a population sample of 248 subjects. A total of 155 postmenopausal women were randomized to 1 of 5 treatment groups for 20 weeks: placebo; propranolol, 20 mg b.i.d.; propranolol, 40 mg b.i.d.; atenolol, 50 mg/day; or nebivolol, 5 mg/day. We took advantage of the ?1-AR selectivity gradient of these drugs (propranolol [nonselective] << atenolol [relatively ?1-AR selective] < nebivolol [highly ?1-AR selective]) to define the ?-AR selectivity for SNS effects on bone. RESULTS:ADRB1 and ADRB2, but not ADRB3, were expressed in human bone; patients treated clinically with ?1-AR-selective blockers had better bone microarchitecture than did nonusers, and relative to placebo, atenolol and nebivolol, but not propranolol, reduced the bone resorption marker serum C-telopeptide of type I collagen (by 19.5% and 20.6%, respectively; P < 0.01) and increased bone mineral density of the ultradistal radius (by 3.6% and 2.9%; P < 0.01 and P < 0.05, respectively). CONCLUSIONS:These 3 independent lines of evidence strongly support a role for adrenergic signaling in the regulation of bone metabolism in humans, principally via ?1-ARs. TRIAL REGISTRATION:ClinicalTrials.gov NCT02467400. FUNDING:This research was supported by the NIH (AG004875 and AR027065) and a Mayo Clinic Clinical and Translational Science Award (CTSA) (UL1 TR002377).

SUBMITTER: Khosla S

PROVIDER: S-EPMC6205387 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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Sympathetic β1-adrenergic signaling contributes to regulation of human bone metabolism.

Khosla Sundeep S Drake Matthew T MT Volkman Tammie L TL Thicke Brianne S BS Achenbach Sara J SJ Atkinson Elizabeth J EJ Joyner Michael J MJ Rosen Clifford J CJ Monroe David G DG Farr Joshua N JN

The Journal of clinical investigation 20181002 11

<h4>Background</h4>Evidence from rodent studies indicates that the sympathetic nervous system (SNS) regulates bone metabolism, principally via β2-adrenergic receptors (β2-ARs). Given the conflicting human data, we used multiple approaches to evaluate the role of the SNS in regulating human bone metabolism.<h4>Methods</h4>Bone biopsies were obtained from 19 young and 19 elderly women for assessment of ADRB1, ADRB2, and ADRB3 mRNA expression. We examined the relationship of β-blocker use to bone m ...[more]

PMID: 30153111

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Project description:CD8+ T cells are essential components of the body’s immune reaction against viral infections and tumors, capable of eliminating infected and cancerous cells. However, when the antigen cannot be cleared, T cells enter a state known as exhaustion. Exhausted CD8+ T cells are characterized by expression of multiple inhibitory receptors, like PD-1 and TIM3 and reduced capacity to secrete cytokines, and are commonly found in chronic viral infections, like HIV and HBV, as well as in immunosuppressive tumor microenvironments (TME). Cancer and chronic infection also place considerable stress on tissue architecture and function, and while it is clear that chronic antigen contributes to CD8+ T cell exhaustion, less is known about how stress responses in tissues regulate T cell function. Here we show a previously undescribed link between the stress-associated catecholamines adrenaline and noradrenaline and the development of T cell exhaustion through the β1-adrenergic receptor, ADRB1. We identify that exhausted CD8+ T cells express higher levels of ADRB1, and exposure of ADRB1-expressing T cells to catecholamines suppresses cytokine production and impairs T cell proliferation. Genetic or pharmacological ablation of β-adrenergic signaling via ADRB1 reduces development of T cell exhaustion in a chronic infection model and improves cytotoxic functions in tumor-infiltrating lymphocytes (TILs) when combined with immune checkpoint blockade (ICB) therapy in a melanoma model. Extending these findings to an ICB-resistant tumor model of murine pancreatic cancer, we show that beta-blockers and ICB synergize to enhance and reprogram T cell responses. Given that malignant disease is associated with increased systemic catecholamine levels in patients and therapeutic stress reduction improves survival in cancer patients, our results demonstrate a potential link between systemic stress, tumor innervation and immune responses. Our findings show that β-adrenergic signaling constitutes a novel targetable immune checkpoint in CD8+ T cells to rejuvenate antitumor functions. More broadly, our results support further clinical investigation into the application of beta-blockers, which are clinically safe and widely prescribed, as an immunomodulating agent for cancer immunotherapy.

Project description:Purpose:Perineural invasion (PNI) is reported to correlate with local recurrence and poor prognosis of salivary adenoid cystic carcinoma (SACC). However, the pathogenesis of PNI remains unclear. The aims of this study were to investigate the correlation between sympathetic innervation and SACC PNI and to elucidate how the sympathetic neurotransmitter norepinephrine (NE) regulates the PNI process. Materials and methods:Sympathetic innervation and ?2-adrenergic receptor (?2-AR) expression in SACC tissues were evaluated by immunohistochemistry. The NE concentrations in SACC tissues and dorsal root ganglia (DRG) coculture models were measured by ELISA. ?2-AR expression in SACC cells was detected by performing quantitative real-time polymerase chain reaction (qRT-PCR) and immunofluorescence assay. SACC cells were treated with NE, the nonselective ?-AR blocker phentolamine, the ?2-AR antagonist ICI118,551, or were transfected with ?2-AR small interfering RNA (siRNA). Proliferation was evaluated in methyl thiazolyl tetrazolium assay, and migration was evaluated in Transwell assay and wound-healing assay. PNI was tested through both Transwell assay and a DRG coculture model. The expressions of epithelial-mesenchymal transition (EMT) markers and matrix metalloproteinases (MMPs) were measured by performing qRT-PCR and Western blot assay. Results:Sympathetic innervation and ?2-AR were highly distributed in SACC tissues and correlated positively with PNI (P=0.035 and P=0.003, respectively). The sympathetic neurotransmitter NE was overexpressed in SACC tissues and DRG coculture models. Exogenously added NE promoted proliferation, migration, and PNI of SACC cells via ?2-AR activation. NE/?2-AR signaling may promote proliferation, migration, and PNI by inducing EMT and upregulating MMPs. However, ?2-AR inhibition with either an antagonist or siRNA abrogated NE-induced PNI. Conclusion:Collectively, our findings reveal the supportive role of sympathetic innervation in the pathogenesis of SACC PNI and suggest ?2-AR as a potential therapeutic target for treating PNI in SACC.

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Sympathetic ?1-adrenergic signaling contributes to regulation of human bone metabolism.

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Sympathetic β1-adrenergic signaling contributes to regulation of human bone metabolism.

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